157 results on '"ROBERTSON, AM"'
Search Results
2. Cost effectiveness analysis of improved blood pressure control in hypertensive patients with type 2 diabetes: UKPDS 40
- Author
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Stearne, MR, Palmer, SL, Hammersley, MS, Franklin, SL, Spivey, RS, Levy, JC, Tidy, CR, Bell, NJ, Steemson, J, Barrow, BA, Coster, R, Waring, K, Nolan, L, Truscott, E, Walravens, N, Cook, L, Lampard, H, Merle, C, Parker, P, McVittie, J, Draisey, I, Murchison, LE, Brunt, AHE, Williams, MJ, Pearson, DW, Petrie, XMP, Lean, MEJ, Walmsley, D, Lyall, F, Christie, E, Church, J, Thomson, E, Farrow, A, Stowers, JM, Stowers, M, McHardy, K, Patterson, N, Wright, AD, Levi, NA, Shearer, ACI, Thompson, RJW, Taylor, G, Rayton, S, Bradbury, M, Glover, A, Smyth-Osbourne, A, Parkes, C, Graham, J, England, P, Gyde, S, Eagle, C, Chakrabarti, B, Smith, J, Sherwell, J, Kohner, EM, Dornhorst, A, Doddridge, MC, Dumskyj, M, Walji, S, Sharp, P, Sleightholm, M, Vanterpool, G, Rose, C, Frost, G, Roseblade, M, Elliott, S, Forrester, S, Foster, M, Myers, K, Chapman, R, Hayes, JR, Henry, RW, Featherston, MS, Archbold, GPR, Copeland, M, Harper, R, Richardson, I, Martin, S, Davison, HA, Hadden, DR, Kennedy, L, Atkinson, AB, Culbert, AM, Hegan, C, Tennet, H, Webb, N, Robinson, I, Holmes, J, Bell, PM, McCance, DR, Rutherford, J, Nesbitt, S, Spathis, AS, Hyer, S, Nanson, ME, James, LM, Tyrell, JM, Davis, C, Strugnell, P, Booth, M, Petrie, H, Clark, D, Rice, B, Hulland, S, Barron, JL, Yudkin, JS, Gould, BJ, Singer, J, Badenock, A, Eckert, M, Alibhai, K, Marriot, E, Cox, C, Price, R, Fernandez, M, Ryle, A, Clarke, S, Wallace, G, Mehmed, E, MacFarlane, S, Greenwood, RH, Wilson, J, Denholm, MJ, Temple, RC, Whitfield, K, Johnson, F, Munroe, C, Gorick, S, Duckworth, E, Flatman, M, Rainbow, S, Borthwick, LJ, Wheatcroft, DJ, Seaman, RJ, Christie, RA, Wheatcroft, W, Musk, P, White, J, McDougal, S, Bond, M, Raniga, P, Newton, RW, Jung, RT, Roxburgh, C, Kilgallon, B, Dick, L, Waugh, N, Kilby, S, Ellington, A, Burns, J, Fox, CV, Holloway, MC, Coghill, HM, Hein, N, Fox, A, Cowan, W, Richard, M, Quested, K, Evans, SJ, Paisey, RB, Brown, NPR, Tucker, AJ, Paisey, R, Garrett, F, Hogg, J, Park, P, Williams, K, Harvey, P, Wilcocks, R, Mason, S, Frost, J, Warren, C, Rocket, P, Bower, L, Roland, JM, Brown, DJ, Youens, J, Stanton-King, K, Mungall, H, Ball, V, Maddison, W, Donnelly, D, King, S, Griffin, P, Smith, S, Church, S, Dunn, G, Wilson, A, Palmer, K, Brown, PM, Humphriss, D, Davidson, AJM, Rose, R, Armistead, L, Townsend, S, Poon, P, Peacock, IDA, Culverwell, NJC, Charlton, MH, Connolly, BPS, Peacock, J, Barrett, J, Wain, J, Beeston, W, King, G, Hill, PG, Boulton, AJM, Robertson, AM, Katoulis, V, Olukoga, A, McDonald, H, Kumar, S, Abouaesha, F, Abuaisha, B, Knowles, EA, Higgins, S, Booker, J, Sunter, J, Breislin, K, Parker, R, Raval, P, Curwell, J, Davenport, J, Shawcross, G, Prest, A, Grey, J, Cole, H, Sereviratne, C, Young, RJ, Dornan, TL, Clyne, JR, Gibson, M, O'Connell, I, Wong, LM, Wilson, SJ, Wright, KL, Wallace, C, McDowell, D, Burden, AC, Sellen, EM, Gregory, R, Roshan, M, Vaghela, N, Burden, M, Sherriff, C, Clarke, J, Grenfell, J, Tooke, JE, MacLeod, K, Searnark, C, Rammell, M, Pym, C, Stockman, J, Yeo, C, Piper, J, Leighton, L, Green, E, Hoyle, M, Jones, K, Hudson, A, James, AJ, Shore, A, Higham, A, Martin, B, and Grp, UKPDS
- Subjects
General Engineering ,HC Economic History and Conditions ,General Earth and Planetary Sciences ,General Medicine ,R Medicine (General) ,General Environmental Science - Abstract
Objectives: To estimate the economic efficiency of tight blood pressure control, with angiotensin converting enzyme inhibitors or beta blockers, compared with less tight control in hypertensive patients with type 2 diabetes. Design: Cost effectiveness analysis incorporating within trial analysis and estimation of impact on life expectancy through use of the within trial hazards of reaching a defined clinical end point. Use of resources driven by trial protocol and use of resources in standard clinical practice were both considered. Setting: 20 hospital based clinics in England, Scotland, and Northern Ireland. Subjects: 1148 hypertensive patients with type 2 diabetes from UK prospective diabetes study randomised to tight control of blood pressure (n=758) or less tight control (n=390). Main outcome measure: Cost effectiveness ratios based on (a) use of healthcare resources associated with tight control and less tight control and treatment of complications and (b) within trial time free from diabetes related end points, and life years gained. Results: Based on use of resources driven by trial protocol, the incremental cost effectiveness of tight control compared with less tight control was cost saving. Based on use of resources in standard clinical practice, incremental cost per extra year free from end points amounted to £1049 (costs and effects discounted at 6% per year) and £434 (costs discounted at 6% per year and effects not discounted). The incremental cost per life year gained was £720 (costs and effects discounted at 6% per year) and £291 (costs discounted at 6% per year and effects not discounted). Conclusions: Tight control of blood pressure in hypertensive patients with type 2 diabetes substantially reduced the cost of complications, increased the interval without complications and survival, and had a cost effectiveness ratio that compares favourably with many accepted healthcare programmes.
- Published
- 1998
3. Intensive blood-glucose control with sulphonylureas or insulin compared with conventional treatment and risk of complications in patients with type 2 diabetes (UKPDS 33)
- Author
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Turner, RC, Holman, RR, Cull, CA, Stratton, IM, Matthews, DR, Frighi, V, Manley, SE, Neil, A, McElroy, K, Wright, D, Kohner, E, Fox, C, Hadden, D, Mehta, Z, Smith, A, Nugent, Z, Peto, R, Adlel, AI, Mann, JI, Bassett, PA, Oakes, SF, Dornan, TL, Aldington, S, Lipinski, H, Collum, R, Harrison, K, MacIntyre, C, Skinner, S, Mortemore, A, Nelson, D, Cockley, S, Levien, S, Bodsworth, L, Willox, R, Biggs, T, Dove, S, Beattie, E, Gradwell, M, Staples, S, Lam, R, Taylor, F, Leung, L, Carter, RD, Brownlee, SM, Fisher, KE, Islam, K, Jelfs, R, Williams, PA, Williams, FA, Sutton, PJ, Ayres, A, Logie, LJ, Lovatt, C, Evans, MA, Stowell, LA, Ross, I, Kennedy, IA, Croft, D, Keen, AH, Rose, C, Raikou, M, Fletcher, AE, Bulpitt, C, Battersby, C, Yudkin, JS, Stevens, R, Stearn, MR, Palmer, SL, Hammersley, MS, Franklin, SL, Spivey, RS, Levy, JC, Tidy, CR, Bell, NJ, Steemson, J, Barrow, BA, Coster, R, Waring, K, Nolan, L, Truscott, E, Walravens, N, Cook, L, Lampard, H, Merle, C, Parker, P, McVittie, J, Draisey, I, Murchison, LE, Brunt, AHE, Williams, MJ, Pearson, DW, Petrie, XMP, Lean, MEJ, Walmsley, D, Lyall, F, Christie, E, Church, J, Thomson, E, Farrow, A, Stowers, JM, Stowers, M, McHardy, K, Patterson, N, Wright, AD, Levi, NA, Shearer, ACI, Thompson, RJW, Taylor, G, Rayton, S, Bradbury, M, Glover, A, Smyth-Osbourne, A, Parkes, C, Graham, J, England, P, Gyde, S, Eagle, C, Chakrabarti, B, Smith, J, Sherwell, J, Oakley, NW, Whitehead, MA, Hollier, GP, Pilkington, T, Simpson, J, Anderson, M, Martin, S, Kean, J, Rice, B, Rolland, A, Nisbet, J, Kohner, EM, Dornhorst, A, Doddridge, MC, Dumskyij, M, Walji, S, Sharp, P, Sleightholm, M, Vanterpool, G, Frost, G, Roseblade, M, Elliott, S, Forrester, S, Foster, M, Myers, K, Chapman, R, Hayes, JR, Henry, RW, Featherston, MS, Archbold, GPR, Copeland, M, Harper, R, Richardson, I, Davison, HA, Alexander, L, Scarpello, JHB, Shiers, DE, Tucker, RJ, Worthington, JRH, Angris, S, Bates, A, Walton, J, Teasdale, M, Browne, J, Stanley, S, Davis, BA, Strange, RC, Hadden, DR, Kennedy, L, Atkinson, AB, Bell, PM, McCance, DR, Rutherford, J, Culbert, AM, Hegan, C, Tennet, H, Webb, N, Robinson, I, Holmes, J, Nesbitt, S, Spathis, AS, Hyer, S, Nanson, ME, James, LM, Tyrell, JM, Davis, C, Strugnell, P, Booth, M, Petrie, H, Clark, D, Hulland, S, Barron, JL, Gould, BC, Singer, J, Badenoch, A, McGregor, M, Isenberg, L, Eckert, M, Alibhai, K, Marriot, E, Cox, C, Price, R, Fernandez, M, Ryle, A, Clarke, S, Wallace, G, Mehmed, E, Lankester, JA, Howard, E, Waite, A, MacFarlane, S, Greenwood, RH, Wilson, J, Denholm, MJ, Temple, RC, Whitfield, K, Johnson, F, Munroe, C, Gorick, S, Duckworth, E, Fatman, M, Rainbow, S, Borthwick, L, Wheatcroft, DJ, Seaman, RJ, Christie, RA, Wheatcroft, W, Musk, P, White, J, McDougal, S, Bond, M, Raniga, P, Day, JL, Doshi, MJ, Wilson, JG, Howard-Williams, JR, Humphreys, H, Graham, A, Hicks, K, Hexman, S, Bayliss, P, Pledger, D, Newton, RW, Jung, RT, Roxburgh, C, Kilgallon, B, Dick, L, Waugh, N, Kilby, S, Ellingford, A, Burns, J, Fox, CV, Holloway, MC, Coghill, HM, Hein, N, Fox, A, Cowan, W, Richard, M, Quested, K, Evans, SJ, Paisey, RB, Brown, NPR, Tucker, AJ, Paisey, R, Garrett, F, Hogg, J, Park, P, Williams, K, Harvey, P, Wilcocks, R, Mason, S, Frost, J, Warren, C, Rocket, P, Bower, L, Roland, JM, Brown, DJ, Youens, J, Stanton-King, K, Mungall, H, Ball, V, Maddison, W, Donnelly, D, King, S, Griffin, P, Smith, S, Church, S, Dunn, G, Wilson, A, Palmer, K, Brown, PM, Humphriss, D, Davidson, AJM, Rose, R, Armistead, L, Townsend, S, Poon, P, Peacock, IDA, Culverwell, NJC, Charlton, MH, Connolly, BPS, Peacock, J, Barrett, J, Wain, J, Beeston, W, King, G, Hill, PG, Boulton, AJM, Robertson, AM, Katoulis, V, Olukoga, A, McDonald, H, Kumar, S, Abouaesha, F, Abuaisha, B, Knowles, EA, Higgins, S, Booker, J, Sunter, J, Breislin, K, Parker, R, Raval, P, Curwell, J, Davenport, H, Shawcross, G, Prest, A, Grey, J, Cole, H, Sereviratne, C, Young, RJ, Clyne, JR, Gibson, M, O'Connell, I, Wong, LM, Wilson, SJ, Wright, KL, Wallace, C, McDowell, D, Burden, AC, Sellen, EM, Gregory, R, Roshan, M, Vaghela, N, Burden, M, Sherriff, C, Mansingh, S, Clarke, J, Grenfell, J, Tooke, JE, MacLeod, K, Seamark, C, Rammell, M, Pym, C, Stockman, J, Yeo, C, Piper, J, Leighton, L, Green, E, Hoyle, M, Jones, K, Hudson, A, James, AJ, Shore, A, Higham, A, Martin, B, Neil, HAW, Butterfield, WJH, Doll, WRS, Eastman, R, Ferris, FR, Kurinij, N, McPherson, K, Mahler, RF, Meade, TW, Shafer, G, Watkins, PJ, Keen, H, Siegel, D, Betteridge, DJ, Cohen, RD, Currie, D, Darbyshire, J, Forrester, JV, Guppy, T, Johnston, DG, McGuire, A, Murphy, M, el-Nahas, AM, Pentecost, B, Spiegelhalter, D, Alberti, KGMM, Denton, R, Home, PD, Howell, S, Jarrett, JR, Marks, V, Marmot, M, Ward, JD, and Grp, UKPDS
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General Medicine - Published
- 1998
4. Tight blood pressure control and risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 38. UK Prospective Diabetes Study Group
- Author
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Stearne, MR, Palmer, SL, Hammersley, MS, Franklin, SL, Spivey, RS, Levy, JC, Tidy, CR, Bell, NJ, Steemson, J, Barrow, BA, Coster, R, Waring, K, Nolan, J, Truscott, E, Walravens, N, Cook, L, Lampard, H, Merle, C, Parker, P, McVittie, J, Draisey, I, Murchison, LE, Brunt, AHE, Williams, MJ, Pearson, DW, Petrie, XMP, Lean, MEJ, Walmsley, D, Lyall, MJ, Christie, E, Church, J, Thomson, E, Farrow, A, Stowers, JM, Stowers, M, McHardy, K, Patterson, N, Wright, AD, Levi, NA, Shearer, ACI, Thompson, RJW, Taylor, G, Rayton, S, Bradbury, M, Glover, A, Smyth-Osbourne, A, Parkes, C, Graham, J, England, P, Gyde, S, Eagle, C, Chakrabarti, B, Smith, J, Sherwell, J, Kohner, EM, Dornhurst, A, Doddridge, MC, Dumskyj, M, Walji, S, Sharp, P, Sleightholm, M, Vanterpool, G, Rose, C, Frost, G, Roseblade, M, Elliott, S, Forrester, S, Foster, M, Myers, K, Chapman, R, Hayes, JR, Henry, RW, Featherston, MS, Archbold, GPR, Copeland, M, Harper, R, Richardson, I, Martin, S, Davison, HA, Hadden, DR, Kennedy, L, Atkinson, AB, Culbert, AM, Hegan, C, Tennet, H, Webb, N, Robinson, I, Holmes, J, Bell, PM, McCance, DR, Rutherford, J, Nesbitt, S, Spathis, AS, Hyer, S, Nanson, ME, James, LM, Tyrell, JM, Davis, C, Strugnell, P, Booth, M, Petrie, H, Clark, D, Rice, B, Hulland, S, Barron, JL, Yudkin, JS, Gould, BJ, Singer, J, Badenock, A, Eckert, M, Alibhai, K, Marriot, E, Cox, C, Price, R, Fernandez, M, Ryle, A, Clarke, S, Wallace, G, Mehmed, E, MacFarlane, S, Greenwood, RH, Wilson, J, Denholm, MJ, Temple, RC, Whitfield, K, Johnson, F, Munroe, C, Gorick, S, Duckworth, E, Flatman, M, Rainbow, S, Borthwick, LJ, Wheatcroft, DJ, Seaman, RJ, Christie, RA, Wheatcroft, W, Musk, P, White, J, McDougal, S, Bond, M, Raniga, P, Newton, RW, Jung, RT, Roxburgh, C, Kilgallon, B, Dick, L, Waugh, N, Kilby, S, Ellingford, A, Burns, J, Fox, CV, Holloway, MC, Coghill, HM, Hein, N, Fox, A, Cowan, W, Richard, M, Quested, K, Evans, SJ, Paisey, RB, Brown, NPR, Tucker, AJ, Paisey, R, Garrett, F, Hogg, J, Park, P, Williams, K, Harvey, P, Wilcocks, R, Mason, S, Frost, J, Warren, C, Rocket, P, Bower, L, Roland, JM, Brown, DJ, Youens, J, Stanton-King, K, Mungall, H, Ball, V, Maddison, W, Donnelly, D, King, S, Griffin, P, Smith, S, Church, S, Dunn, G, Wilson, A, Palmer, K, Brown, PM, Humphriss, D, Davidson, AJM, Rose, R, Armistead, L, Townsend, S, Poon, P, Peacock, IDA, Culverwell, NJC, Charlton, MH, Connolly, BPS, Peacock, J, Barrett, J, Wain, J, Beeston, W, King, G, Hill, PG, Boulton, AJM, Robertson, AM, Katoulis, V, Olukoga, A, McDonald, H, Kumar, S, Abouaesha, F, Abuaisha, B, Knowles, EA, Higgins, S, Booker, J, Sunter, J, Breislin, K, Parker, R, Raval, P, Curwell, J, Davenport, H, Shawcross, G, Prest, A, Grey, J, Cole, H, Sereviratne, C, Young, RJ, Dornan, TL, Clyne, JR, Gibson, M, O'Connell, I, Wong, LM, Wilson, SJ, Wright, KL, Wallace, C, McDowell, D, Burden, AC, Sellen, EM, Gregory, R, Roshan, M, Vaghela, N, Burden, M, Sherriff, C, Clarke, J, Grenfell, J, Tooke, JE, MacLeod, K, Searnark, C, Rammell, M, Pym, C, Stockman, J, Yeo, C, Piper, J, Leighton, L, Green, E, Hoyle, M, Jones, K, Hudson, A, James, AJ, Shore, A, Higham, A, Martin, B, and Grp, USPDS
- Abstract
OBJECTIVE: To determine whether tight control of blood pressure prevents macrovascular and microvascular complications in patients with type 2 diabetes. DESIGN: Randomised controlled trial comparing tight control of blood pressure aiming at a blood pressure of
- Published
- 1998
5. Efficacy of atenolol and captopril in reducing risk of macrovascular and microvascular complications in type 2 diabetes: UKPDS 39. UK Prospective Diabetes Study Group
- Author
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Stearne, MR, Palmer, SL, Hammersley, MS, Franklin, SL, Spivey, RS, Levy, JC, Tidy, CR, Bell, NJ, Steemson, J, Barrow, BA, Coster, R, Waring, K, Nolan, L, Truscott, E, Walravens, N, Cook, BL, Lampard, H, Merle, C, Parker, P, McVittie, J, Draisey, I, Murchison, LE, Brunt, AHE, Williams, MJ, Pearson, DW, Petrie, XMP, Lean, MEJ, Walmsley, D, Lyall, F, Christie, E, Church, J, Thomson, E, Farrow, A, Stowers, JM, Stowers, M, McHardy, K, Patterson, N, Wright, AD, Levi, NA, Shearer, AGI, Thompson, RJW, Taylor, G, Rayton, S, Bradbury, M, Glover, A, Smyth-Osbourne, A, Parkes, C, Graham, J, England, P, Gyde, S, Eagle, C, Chakrabarti, B, Smith, J, Sherwell, J, Kohner, EM, Dornhorst, A, Doddridge, MC, Dumskyj, M, Walji, S, Sharp, P, Sleightholm, M, Vanterpool, G, Rose, C, Frost, G, Roseblade, M, Elliott, S, Forrester, S, Foster, M, Myers, K, Chapman, R, Hayes, JR, Henry, TW, Featherston, MS, Archbold, GPR, Copeland, M, Harper, R, Richardson, I, Martin, S, Davison, HA, Hadden, DR, Kennedy, L, Atkinson, AB, Culbert, AM, Hegan, C, Tennet, H, Webb, N, Robinson, I, Holmes, J, Bell, PM, McCance, DR, Rutherford, J, Nesbitt, S, Spathis, AS, Hyer, S, Nanson, ME, James, JM, Tyrell, JM, Davis, C, Strugnell, P, Booth, M, Petrie, H, Clark, D, Rice, B, Hulland, S, Barron, JL, Yudkin, JS, Gould, BJ, Singer, J, Badenock, A, Eckert, M, Alibhai, K, Marriot, E, Cox, C, Price, R, Fernandez, M, Ryle, A, Clarke, S, Wallace, G, Mehmed, E, MacFarlane, S, Greenwood, RH, Wilson, J, Denholm, MJ, Temple, RC, Whitfield, K, Johnson, F, Munroe, C, Gorick, S, Duckworth, E, Flatman, M, Rainbow, S, Borthwick, LJ, Wheatcroft, DJ, Seaman, RJ, Christie, RA, Wheatcroft, W, Musk, P, White, J, McDougal, S, Bond, M, Raniga, P, Newton, RW, Jung, RT, Roxburgh, C, Kilgallon, B, Dick, L, Waugh, N, Kilby, S, Ellingford, A, Burns, J, Fox, CV, Holloway, MC, Coghill, HM, Hein, N, Fox, A, Cowan, W, Richard, M, Quested, K, Evans, SJ, Paisey, RB, Brown, NPR, Tucker, AJ, Paisey, R, Garrett, F, Hogg, J, Park, P, Williams, K, Harvey, P, Wilcocks, R, Mason, S, Frost, J, Warren, C, Rocket, P, Bower, L, Roland, JM, Brown, DJ, Youens, J, Stanton-King, K, Mungall, H, Ball, V, Maddison, W, Donnelly, D, King, S, Griffin, P, Smith, S, Church, S, Dunn, G, Wilson, A, Palmer, K, Brown, PM, Humphriss, D, Davidson, AJM, Rose, R, Armistead, L, Townsend, S, Poon, P, Peacock, IDA, Culverwell, NJC, Charlton, MH, Connolly, BPS, Peacock, J, Barrett, J, Wain, J, Beeston, W, King, G, Hill, PG, Boulton, AJM, Robertson, AM, Katoulis, V, Olukoga, A, McDonald, H, Kumar, S, Abouaesha, F, Abuaisha, B, Knowles, EA, Higgins, S, Booker, J, Sunter, J, Breislin, K, Parker, R, Raval, P, Curwell, J, Davenport, H, Shawcross, G, Prest, A, Grey, J, Cole, H, Sereviratne, C, Young, RJ, Dornan, TL, Clyne, JR, Gibson, M, O'Connell, I, Wong, LM, Wilson, SJ, Wright, KL, Wallace, C, McDowell, D, Burden, AC, Sellen, EM, Gregory, R, Roshan, M, Vaghela, N, Burden, M, Sherriff, C, Clarke, J, Grenfell, J, Tooke, JE, MacLeod, K, Searnark, C, Rammell, M, Pym, C, Stockman, J, Yeo, C, Piper, J, Leighton, L, Green, E, Hoyle, M, Jones, K, Hudson, A, James, AJ, Shore, A, Higham, A, Martin, B, and Grp, USPDS
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cardiovascular diseases ,circulatory and respiratory physiology - Abstract
OBJECTIVE: To determine whether tight control of blood pressure with either a beta blocker or an angiotensin converting enzyme inhibitor has a specific advantage or disadvantage in preventing the macrovascular and microvascular complications of type 2 diabetes. DESIGN: Randomised controlled trial comparing an angiotensin converting enzyme inhibitor (captopril) with a beta blocker (atenolol) in patients with type 2 diabetes aiming at a blood pressure of =300 mg/l (5% and 9%). The proportion of patients with hypoglycaemic attacks was not different between groups, but mean weight gain in the atenolol group was greater (3.4 kg v 1.6 kg). CONCLUSION: Blood pressure lowering with captopril or atenolol was similarly effective in reducing the incidence of diabetic complications. This study provided no evidence that either drug has any specific beneficial or deleterious effect, suggesting that blood pressure reduction in itself may be more important than the treatment used.
- Published
- 1998
6. Protein restriction for diabetic renal disease
- Author
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Waugh, NR, primary and Robertson, AM, additional
- Published
- 1997
- Full Text
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7. Cell-Wall Histochemistry and Anatomy of Taro (Colocasia esculenta.)
- Author
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Harris, PJ, primary, Ferguson, LR, additional, Robertson, AM, additional, Mckenzie, RJ, additional, and White, JB, additional
- Published
- 1992
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8. Room for (performance) improvement: provider-related factors associated with poor outcomes in massive transfusion.
- Author
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Cotton BA, Dossett LA, Au BK, Nunez TC, Robertson AM, and Young PP
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- 2009
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9. Predefined massive transfusion protocols are associated with a reduction in organ failure and postinjury complications.
- Author
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Cotton BA, Au BK, Nunez TC, Gunter OL, Robertson AM, and Young PP
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- 2009
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10. DISCUSSION. PETERHEAD, SCOTLAND`S 100-YEAR HARBOUR OF REFUGE.
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BUCHAN, AR, LEONARD, JM, and ROBERTSON, AM
- Published
- 1985
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11. Prickly Heat and Tropical Pemphigus
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Robertson Am
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medicine.medical_specialty ,Pemphigus ,business.industry ,medicine ,General Medicine ,medicine.disease ,business ,Dermatology - Published
- 1945
12. Neurological, psychological and educational sequelae of low birth weight
- Author
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Dunn, HG, primary, Crichton, JU, additional, Grunau, RVE, additional, McBurney, A Karaa, additional, McCormick, AQ, additional, Robertson, AM, additional, and Schulzer, M, additional
- Published
- 1980
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13. DISCUSSION. PETERHEAD, SCOTLAND`S 100-YEAR HARBOUR OF REFUGE.
- Author
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BUCHAN, AR, primary, ROBERTSON, AM, additional, and LEONARD, JM, additional
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- 1985
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14. Prevalence and correlates of 'agua celeste' use among female sex workers who inject drugs in Ciudad Juarez, Mexico.
- Author
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Morris MD, Case P, Robertson AM, Lozada R, Vera A, Clapp JD, Medina-Mora ME, Strathdee SA, Morris, Meghan D, Case, Patricia, Robertson, Angela M, Lozada, Remedios, Vera, Alicia, Clapp, John D, Medina-Mora, Maria Elena, and Strathdee, Steffanie A
- Abstract
Background: Agua celeste, or "heavenly water", is the street name for a sky-blue colored solvent reportedly inhaled or ingested to produce an intoxicating effect. Study aims were to (1) describe prevalence of agua celestse (AC) use, and (2) identify correlates of lifetime and recent use of AC use among female sex workers who also inject drugs (FSW-IDUs) in northern Mexico.Methods: Between 2008 and 2010, baseline data from FSW-IDUs≥18 years old living in Tijuana or Ciudad Juarez participating in a longitudinal behavioral intervention were analyzed using logistic regression.Results: Among 623 FSW-IDUs (307 from Tijuana and 316 from Ciudad Juarez (CJ)), 166 (26%) reported ever using AC, all of whom lived in CJ. Among the CJ sample, lifetime prevalence of AC use was 53%, median age of first use was 16 years (IQR: 14-23), and 10% reported it as their first abused substance. Ever using AC was independently associated with ever being physically abused and younger age, and was marginally associated with initiating injection drug use and regular sex work at age eighteen or younger. Among those ever using AC, 70/166 (42.2%) reported using it within the last 6 months, which was independently associated with using drugs with clients before or during sex, being on the street more than 8h per day, and younger age.Discussion: We observed considerable geographic variation in the use of AC in northern Mexico. Future studies exploring factors influencing use, its precise formulation(s), and its potential health effects are needed to guide prevention and treatment. [ABSTRACT FROM AUTHOR]- Published
- 2011
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15. Management of pyrrhotite tailings: a ten year case study on continuous learning and improvement
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Robertson, AM, Kawashima, N, Smart, RStC, Schumann, R, and Mineralogy Of Mine Site Neutralising Materials Adelaide, Australia 29 April-2 May 2014
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Savannah Nickel Mine ,pyrrhotite tailings ,tailing materials - Abstract
This paper presents case study information on the geochemical and mineralogical nature of tailing materials generated at Savannah Nickel Mine in the Kimberley region of Western Australia (WA). The mine is an underground operation, and tailings generated from processing ore are stored at an above-ground valley fill Tailings Storage Facility (TSF). Various studies have shown that leaving the tailings in situ at mine closure and using a cover system will produce a sustainable environmental outcome, and the mine operator has recently received regulatory approval to increase the capacity of the TSF and implement this closure strategy Over the past decade, geochemical and mineralogical studies have demonstrated that the geochemical behaviour of the tailings in the TSF is much more benign than initially predicted. Despite containing almost 30% pyrrhotite, the tailings generate only a fraction of the acidity predicted by classical static geochemical test techniques, and the rate of acidity generation is more than compensated by the inherent non-carbonate acid neutralising capacity available from specific silicate minerals within the tailings matrix. The mine operator now has a very good understanding of the geochemistry of the tailings, although geochemical, mineralogical and other related studies are continuing, moving towards mine closure. Refereed/Peer-reviewed
- Published
- 2014
16. Understanding tailings geochemistry-continuous learning and innovation when planning for mine closure
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Robertson, AM, Kawashima, N, Smart, RStC, Schumann, R, and Life-of-Mine Conference 2012 : Maximising Rehabilitation Outcomes Brisbane, Australia 10-12 July 2012
- Subjects
mine tailings ,mine waste ,environmental impact - Abstract
This paper focuses on a case study at a base metal mine located in a trop ical semi-arid ar ea of Western Australia (WA). It is demonstrated that understanding the geochemical nature of the mine tailings forms an integral part of innovative management strategies developed throughout the life-of-mine (LaM) when planning for mine closure. The tailings are currently stored at an above-ground valley fill tailings storage facility (TSF) and one option for long-term management under consideration is leaving the tailings ill situ at mine closure and covering using the concept of an enhanced 'store and release' cover system. Extensive geochemical and mineralogical studies have found that the geochemical behaviour of the tailings in the TSF is significant ly more benign than initially predicted . The sulfide content of the tailings is primarily pyrrhotite, which can be acid-forming, acid-neutral or acid-consuming depending on a number of factors including redox conditions. Tailings pore water at depth is pH neutral with excess alkalinity, low concentrations of dissolved metals and elevated sulfate concentration. Recent geochemical tests on tailings samples indicate that a reduction in the acid potential and a corresponding increase in the neutralising potential of the tailings, through partial removal of pyrrhotite at the ore processing stage, has the potential to further reduce the long-term risk of potential impact to the environment from any TSF seepage.The current work program investigates whether partial removal of pyrrhotite is feasible and secondly, whether this approach is necessary to produce a significantly better outcome at mine closure.
- Published
- 2012
17. Improving multiple stressor-response models through the inclusion of nonlinearity and interactions among stressor gradients.
- Author
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Robertson AM, Piggott JJ, and Penk MR
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- Phosphorus analysis, Ireland, Water Pollutants, Chemical, Animals, Models, Theoretical, Environmental Monitoring methods, Rivers chemistry, Ecosystem
- Abstract
Stressor-response models are used to detect and predict changes within ecosystems in response to anthropogenic and naturally occurring stressors. While nonlinear stressor-response relationships and interactions between stressors are common in nature, predictive models often do not account for them due to perceived difficulties in the interpretation of results. We used Irish river monitoring data from 177 river sites to investigate if multiple stressor-response models can be improved by accounting for nonlinearity, interactions in stressor-response relationships and environmental context dependencies. Out of the six models of distinct biological responses, five models benefited from the inclusion of nonlinearity while all six benefited from the inclusion of interactions. The addition of nonlinearity means that we can better see the exponential increase in Trophic Diatom Index (TDI3) as phosphorus increases, inferring ecological conditions deteriorating at a faster rate with increasing phosphorus. Furthermore, our results show that the relationship between stressor and response has the potential to be dependent on other variables, as seen in the interaction of elevation with both siltation and nutrients in relation to Ephemeroptera, Plecoptera and Trichoptera (EPT) richness. Both relationships weakened at higher elevations, perhaps demonstrating that there is a decreased capacity for resilience to stressors at lower elevations due to greater cumulative effects. Understanding interactions such as this is vital to managing ecosystems. Our findings provide empirical support for the need to further develop and employ more complex modelling techniques in environmental assessment and management., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)
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- 2024
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18. Description of the local hemodynamic environment in intracranial aneurysm wall subdivisions.
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Karnam Y, Mut F, Yu AK, Cheng B, Amin-Hanjani S, Charbel FT, Woo HH, Niemelä M, Tulamo R, Jahromi BR, Frösen J, Tobe Y, Robertson AM, and Cebral JR
- Subjects
- Humans, Male, Female, Models, Cardiovascular, Stress, Mechanical, Middle Aged, Finite Element Analysis, Intracranial Aneurysm physiopathology, Hemodynamics physiology
- Abstract
Intracranial aneurysms (IAs) pose severe health risks influenced by hemodynamics. This study focuses on the intricate characterization of hemodynamic conditions within the IA walls and their influence on bleb development, aiming to enhance understanding of aneurysm stability and the risk of rupture. The methods emphasized utilizing a comprehensive dataset of 359 IAs and 213 IA blebs from 268 patients to reconstruct patient-specific vascular models, analyzing blood flow using finite element methods to solve the unsteady Navier-Stokes equations, the segmentation of aneurysm wall subregions and the hemodynamic metrics wall shear stress (WSS), its metrics, and the critical points in WSS fields were computed and analyzed across different aneurysm subregions defined by saccular, streamwise, and topographical divisions. The results revealed significant variations in these metrics, correlating distinct hemodynamic environments with wall features on the aneurysm walls, such as bleb formation. Critical findings indicated that regions with low WSS and high OSI, particularly in the body and central regions of aneurysms, are prone to conditions that promote bleb formation. Conversely, areas exposed to high WSS and positive divergence, like the aneurysm neck, inflow, and outflow regions, exhibited a different but substantial risk profile for bleb development, influenced by flow impingements and convergences. These insights highlight the complexity of aneurysm behavior, suggesting that both high and low-shear environments can contribute to aneurysm pathology through distinct mechanisms., (© 2024 The Author(s). International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.)
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- 2024
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19. Distribution of rupture sites and blebs on intracranial aneurysm walls suggests distinct rupture patterns in ACom and MCA aneurysms.
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Karnam Y, Mut F, Yu AK, Cheng B, Amin-Hanjani S, Charbel FT, Woo HH, Niemelä M, Tulamo R, Jahromi BR, Frösen J, Tobe Y, Robertson AM, and Cebral JR
- Subjects
- Humans, Male, Female, Middle Aged, Hemodynamics physiology, Aged, Adult, Risk Factors, Models, Cardiovascular, Middle Cerebral Artery physiopathology, Intracranial Aneurysm physiopathology, Aneurysm, Ruptured physiopathology
- Abstract
The mechanisms behind intracranial aneurysm formation and rupture are not fully understood, with factors such as location, patient demographics, and hemodynamics playing a role. Additionally, the significance of anatomical features like blebs in ruptures is debated. This highlights the necessity for comprehensive research that combines patient-specific risk factors with a detailed analysis of local hemodynamic characteristics at bleb and rupture sites. Our study analyzed 359 intracranial aneurysms from 268 patients, reconstructing patient-specific models for hemodynamic simulations based on 3D rotational angiographic images and intraoperative videos. We identified aneurysm subregions and delineated rupture sites, characterizing blebs and their regional overlap, employing statistical comparisons across demographics, and other risk factors. This work identifies patterns in aneurysm rupture sites, predominantly at the dome, with variations across patient demographics. Hypertensive and anterior communicating artery (ACom) aneurysms showed specific rupture patterns and bleb associations, indicating two pathways: high-flow in ACom with thin blebs at impingement sites and low-flow, oscillatory conditions in middle cerebral artery (MCA) aneurysms fostering thick blebs. Bleb characteristics varied with gender, age, and smoking, linking rupture risks to hemodynamic factors and patient profiles. These insights enhance understanding of the hemodynamic mechanisms leading to rupture events. This analysis elucidates the role of localized hemodynamics in intracranial aneurysm rupture, challenging the emphasis on location by revealing how flow variations influence stability and risk. We identify two pathways to wall failure-high-flow and low-flow conditions-highlighting the complexity of aneurysm behavior. Additionally, this research advances our knowledge of how inherent patient-specific characteristics impact these processes, which need further investigation., (© 2024 The Author(s). International Journal for Numerical Methods in Biomedical Engineering published by John Wiley & Sons Ltd.)
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- 2024
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20. Studying interactions among anthropogenic stressors in freshwater ecosystems: A systematic review of 2396 multiple-stressor experiments.
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Orr JA, Macaulay SJ, Mordente A, Burgess B, Albini D, Hunn JG, Restrepo-Sulez K, Wilson R, Schechner A, Robertson AM, Lee B, Stuparyk BR, Singh D, O'Loughlin I, Piggott JJ, Zhu J, Dinh KV, Archer LC, Penk M, Vu MTT, Juvigny-Khenafou NPD, Zhang P, Sanders P, Schäfer RB, Vinebrooke RD, Hilt S, Reed T, and Jackson MC
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- Human Activities, Stress, Physiological, Ecosystem, Fresh Water
- Abstract
Understanding the interactions among anthropogenic stressors is critical for effective conservation and management of ecosystems. Freshwater scientists have invested considerable resources in conducting factorial experiments to disentangle stressor interactions by testing their individual and combined effects. However, the diversity of stressors and systems studied has hindered previous syntheses of this body of research. To overcome this challenge, we used a novel machine learning framework to identify relevant studies from over 235,000 publications. Our synthesis resulted in a new dataset of 2396 multiple-stressor experiments in freshwater systems. By summarizing the methods used in these studies, quantifying trends in the popularity of the investigated stressors, and performing co-occurrence analysis, we produce the most comprehensive overview of this diverse field of research to date. We provide both a taxonomy grouping the 909 investigated stressors into 31 classes and an open-source and interactive version of the dataset (https://jamesaorr.shinyapps.io/freshwater-multiple-stressors/). Inspired by our results, we provide a framework to help clarify whether statistical interactions detected by factorial experiments align with stressor interactions of interest, and we outline general guidelines for the design of multiple-stressor experiments relevant to any system. We conclude by highlighting the research directions required to better understand freshwater ecosystems facing multiple stressors., (© 2024 The Author(s). Ecology Letters published by John Wiley & Sons Ltd.)
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- 2024
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21. Hypoxanthine Induces Signs of Bladder Aging With Voiding Dysfunction and Lower Urinary Tract Remodeling.
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Birder LA, Wolf-Johnston AS, Zabbarova I, Ikeda Y, Robertson AM, Cardozo R, Azari F, Kanai AJ, Kuchel GA, and Jackson EK
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- Animals, Female, Rats, Biomarkers metabolism, Lower Urinary Tract Symptoms physiopathology, Lower Urinary Tract Symptoms metabolism, Disease Models, Animal, Rats, Inbred F344, Oxidative Stress, Urinary Bladder physiopathology, Urinary Bladder pathology, Urinary Bladder metabolism, Urinary Bladder drug effects, Aging physiology, Hypoxanthine, Reactive Oxygen Species metabolism
- Abstract
Background: Lower urinary tract syndrome (LUTS) is a group of urinary tract symptoms and signs that can include urinary incontinence. Advancing age is a major risk factor for LUTS; however, the underlying biochemical mechanisms of age-related LUTS remain unknown. Hypoxanthine (HX) is a purine metabolite associated with generation of tissue-damaging reactive oxygen species (ROS). This study tested the hypothesis that exposure of the adult bladder to HX-ROS over time damages key LUT elements, mimicking qualitatively some of the changes observed with aging., Methods: Adult 3-month-old female Fischer 344 rats were treated with vehicle or HX (10 mg/kg/day; 3 weeks) administered in drinking water. Targeted purine metabolomics and molecular approaches were used to assess purine metabolites and biomarkers for oxidative stress and cellular damage. Biomechanical approaches assessed LUT structure and measurements of LUT function (using custom-metabolic cages and cystometry) were also employed., Results: HX exposure increased biomarkers indicative of oxidative stress, pathophysiological ROS production, and depletion of cellular energy with declines in NAD+ levels. Moreover, HX treatment caused bladder remodeling and decreased the intercontraction interval and leak point pressure (surrogate measure to assess stress urinary incontinence)., Conclusions: These studies provide evidence that in adult rats chronic exposure to HX causes changes in voiding behavior and in bladder structure resembling alterations observed with aging. These results suggest that increased levels of uro-damaging HX were associated with ROS/oxidative stress-associated cellular damage, which may be central to age-associated development of LUTS, opening up potential opportunities for geroscience-guided interventions., (© The Author(s) 2023. Published by Oxford University Press on behalf of The Gerontological Society of America.)
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- 2024
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22. GEOMETRIC CHARACTERIZATION OF RAT URINARY BLADDER WALL DURING EX-VIVO FILLING USING MICRO-COMPUTED TOMOGRAPHY (MICRO-CT).
- Author
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Azari F, Robertson AM, and Birder LA
- Abstract
Current mechanical models of the bladder largely idealize the bladder as spherical with uniform thickness. This present study aims to investigate this idealization using micro-CT to generate 3D reconstructed models of rat bladders at 10-20 micrometer resolution in both voided and filled states. Applied to three rat bladders, this approach identifies shape, volume, and thickness variations under different pressures. These results demonstrate the filling/voiding process is far from the idealized spherical inflation/contraction. However, the geometry idealizations may be reasonable in cases where the filled bladder geometry is of importance, such as in studies of growth and remodeling.
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- 2024
23. Quantifying Smooth Muscles Regional Organization in the Rat Bladder Using Immunohistochemistry, Multiphoton Microscopy and Machine Learning.
- Author
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Asadbeygi A, Tobe Y, Yoshimura N, Stocker SD, Watkins S, Watton P, and Robertson AM
- Abstract
The smooth muscle bundles (SMBs) in the bladder act as contractile elements which enable the bladder to void effectively. In contrast to skeletal muscles, these bundles are not highly aligned, rather they are oriented more heterogeneously throughout the bladder wall. In this work, for the first time, this regional orientation of the SMBs is quantified across the whole bladder, without the need for optical clearing or cryosectioning. Immunohistochemistry staining was utilized to visualize smooth muscle cell actin in multiphoton microscopy (MPM) images of bladder smooth muscle bundles (SMBs). Feature vectors for each pixel were generated using a range of filters, including Gaussian blur, Gaussian gradient magnitude, Laplacian of Gaussian, Hessian eigenvalues, structure tensor eigenvalues, Gabor, and Sobel gradients. A Random Forest classifier was subsequently trained to automate the segmentation of SMBs in the MPM images. Finally, the orientation of SMBs in each bladder region was quantified using the CT-FIRE package. This information is essential for biomechanical models of the bladder that include contractile elements.
- Published
- 2024
24. Inland recreational fisheries contribute nutritional benefits and economic value but are vulnerable to climate change.
- Author
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Lynch AJ, Embke HS, Nyboer EA, Wood LE, Thorpe A, Phang SC, Viana DF, Golden CD, Milardi M, Arlinghaus R, Baigun C, Beard TD Jr, Cooke SJ, Cowx IG, Koehn JD, Lyach R, Potts W, Robertson AM, Schmidhuber J, and Weyl OLF
- Subjects
- Humans, Animals, Fishes, Canada, Germany, Austria, Slovakia, Conservation of Natural Resources economics, Fresh Water, Climate Change economics, Fisheries economics, Recreation, Nutritive Value
- Abstract
Inland recreational fishing is primarily considered a leisure-driven activity in freshwaters, yet its harvest can contribute to food systems. Here we estimate that the harvest from inland recreational fishing equates to just over one-tenth of all reported inland fisheries catch globally. The estimated total consumptive use value of inland recreational fish destined for human consumption may reach US$9.95 billion annually. We identify Austria, Canada, Germany and Slovakia as countries above the third quantile for nutrition, economic value and climate vulnerability. These results have important implications for populations dependent on inland recreational fishing for food. Our findings can inform climate adaptation planning for inland recreational fisheries, particularly those not currently managed as food fisheries., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)
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- 2024
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25. Comapping Cellular Content and Extracellular Matrix with Hemodynamics in Intact Arterial Tissues Using Scanning Immunofluorescent Multiphoton Microscopy.
- Author
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Tobe Y, Robertson AM, Ramezanpour M, Cebral JR, Watkins SC, Charbel FT, Amin-Hanjani S, Yu AK, Cheng BC, and Woo HH
- Subjects
- Myocytes, Smooth Muscle physiology, Myocytes, Smooth Muscle cytology, Actins metabolism, Animals, Collagen metabolism, Humans, Elastin metabolism, Elastin analysis, Imaging, Three-Dimensional methods, Arteries, Extracellular Matrix, Hemodynamics, Microscopy, Fluorescence, Multiphoton methods
- Abstract
Deviation of blood flow from an optimal range is known to be associated with the initiation and progression of vascular pathologies. Important open questions remain about how the abnormal flow drives specific wall changes in pathologies such as cerebral aneurysms where the flow is highly heterogeneous and complex. This knowledge gap precludes the clinical use of readily available flow data to predict outcomes and improve treatment of these diseases. As both flow and the pathological wall changes are spatially heterogeneous, a crucial requirement for progress in this area is a methodology for acquiring and comapping local vascular wall biology data with local hemodynamic data. Here, we developed an imaging pipeline to address this pressing need. A protocol that employs scanning multiphoton microscopy was developed to obtain three-dimensional (3D) datasets for smooth muscle actin, collagen, and elastin in intact vascular specimens. A cluster analysis was introduced to objectively categorize the smooth muscle cells (SMC) across the vascular specimen based on SMC actin density. Finally, direct quantitative comparison of local flow and wall biology in 3D intact specimens was achieved by comapping both heterogeneous SMC data and wall thickness to patient-specific hemodynamic results., Competing Interests: Conflict of Interest: The authors declare that they have no competing interest., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Microscopy Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
- Published
- 2024
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26. Evaluation of predictive models of aneurysm focal growth and bleb development using machine learning techniques.
- Author
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Hadad S, Mut F, Slawski M, Robertson AM, and Cebral JR
- Subjects
- Humans, Cross-Sectional Studies, Hemodynamics, Machine Learning, Intracranial Aneurysm diagnostic imaging, Intracranial Aneurysm surgery, Aneurysm, Ruptured surgery
- Abstract
Background: The presence of blebs increases the rupture risk of intracranial aneurysms (IAs)., Objective: To evaluate whether cross-sectional bleb formation models can identify aneurysms with focalized enlargement in longitudinal series., Methods: Hemodynamic, geometric, and anatomical variables derived from computational fluid dynamics models of 2265 IAs from a cross-sectional dataset were used to train machine learning (ML) models for bleb development. ML algorithms, including logistic regression, random forest, bagging method, support vector machine, and K-nearest neighbors, were validated using an independent cross-sectional dataset of 266 IAs. The models' ability to identify aneurysms with focalized enlargement was evaluated using a separate longitudinal dataset of 174 IAs. Model performance was quantified by the area under the receiving operating characteristic curve (AUC), the sensitivity and specificity, positive predictive value, negative predictive value, F1 score, balanced accuracy, and misclassification error., Results: The final model, with three hemodynamic and four geometrical variables, along with aneurysm location and morphology, identified strong inflow jets, non-uniform wall shear stress with high peaks, larger sizes, and elongated shapes as indicators of a higher risk of focal growth over time. The logistic regression model demonstrated the best performance on the longitudinal series, achieving an AUC of 0.9, sensitivity of 85%, specificity of 75%, balanced accuracy of 80%, and a misclassification error of 21%., Conclusions: Models trained with cross-sectional data can identify aneurysms prone to future focalized growth with good accuracy. These models could potentially be used as early indicators of future risk in clinical practice., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2024
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27. Pathophysiology of Overactive Bladder and Pharmacologic Treatments Including β3-Adrenoceptor Agonists -Basic Research Perspectives.
- Author
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Kwon J, Kim DY, Cho KJ, Hashimoto M, Matsuoka K, Kamijo T, Wang Z, Karnup S, Robertson AM, Tyagi P, and Yoshimura N
- Abstract
Overactive bladder (OAB) is a symptom-based syndrome defined by urinary urgency, frequency, and nocturia with or without urge incontinence. The causative pathology is diverse; including bladder outlet obstruction (BOO), bladder ischemia, aging, metabolic syndrome, psychological stress, affective disorder, urinary microbiome, localized and systemic inflammatory responses, etc. Several hypotheses have been suggested as mechanisms of OAB generation; among them, neurogenic, myogenic, and urothelial mechanisms are well-known hypotheses. Also, a series of local signals called autonomous myogenic contraction, micromotion, or afferent noises, which can occur during bladder filling, may be induced by the leak of acetylcholine (ACh) or urothelial release of adenosine triphosphate (ATP). They can be transmitted to the central nervous system through afferent fibers to trigger coordinated urgency-related detrusor contractions. Antimuscarinics, commonly known to induce smooth muscle relaxation by competitive blockage of muscarinic receptors in the parasympathetic postganglionic nerve, have a minimal effect on detrusor contraction within therapeutic doses. In fact, they have a predominant role in preventing signals in the afferent nerve transmission process. β3-adrenergic receptor (AR) agonists inhibit afferent signals by predominant inhibition of mechanosensitive Aδ-fibers in the normal bladder. However, in pathologic conditions such as spinal cord injury, it seems to inhibit capsaicin-sensitive C-fibers. Particularly, mirabegron, a β3-agonist, prevents ACh release in the BOO-induced detrusor overactivity model by parasympathetic prejunctional mechanisms. A recent study also revealed that vibegron may have 2 mechanisms of action: inhibition of ACh from cholinergic efferent nerves in the detrusor and afferent inhibition via urothelial β3-AR.
- Published
- 2024
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28. Phenotyping calcification in vascular tissues using artificial intelligence.
- Author
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Ramezanpour M, Robertson AM, Tobe Y, Jia X, and Cebral JR
- Abstract
Vascular calcification is implicated as an important factor in major adverse cardiovascular events (MACE), including heart attack and stroke. A controversy remains over how to integrate the diverse forms of vascular calcification into clinical risk assessment tools. Even the commonly used calcium score for coronary arteries, which assumes risk scales positively with total calcification, has important inconsistencies. Fundamental studies are needed to determine how risk is influenced by the diverse calcification phenotypes. However, studies of these kinds are hindered by the lack of high-throughput, objective, and non-destructive tools for classifying calcification in imaging data sets. Here, we introduce a new classification system for phenotyping calcification along with a semi-automated, non-destructive pipeline that can distinguish these phenotypes in even atherosclerotic tissues. The pipeline includes a deep-learning-based framework for segmenting lipid pools in noisy μ-CT images and an unsupervised clustering framework for categorizing calcification based on size, clustering, and topology. This approach is illustrated for five vascular specimens, providing phenotyping for thousands of calcification particles across as many as 3200 images in less than seven hours. Average Dice Similarity Coefficients of 0.96 and 0.87 could be achieved for tissue and lipid pool, respectively, with training and validation needed on only 13 images despite the high heterogeneity in these tissues. By introducing an efficient and comprehensive approach to phenotyping calcification, this work enables large-scale studies to identify a more reliable indicator of the risk of cardiovascular events, a leading cause of global mortality and morbidity., Competing Interests: Competing Interest Statement: The authors declare no conflict of interest.
- Published
- 2024
29. Computational fluid dynamics-based virtual angiograms for the detection of flow stagnation in intracranial aneurysms.
- Author
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Hadad S, Karnam Y, Mut F, Lohner R, Robertson AM, Kaneko N, and Cebral JR
- Subjects
- Humans, Contrast Media, Hydrodynamics, Angiography, Digital Subtraction, Hemodynamics, Imaging, Three-Dimensional, Intracranial Aneurysm diagnostic imaging
- Abstract
The goal of this study was to test if CFD-based virtual angiograms could be used to automatically discriminate between intracranial aneurysms (IAs) with and without flow stagnation. Time density curves (TDC) were extracted from patient digital subtraction angiography (DSA) image sequences by computing the average gray level intensity inside the aneurysm region and used to define injection profiles for each subject. Subject-specific 3D models were reconstructed from 3D rotational angiography (3DRA) and computational fluid dynamics (CFD) simulations were performed to simulate the blood flow inside IAs. Transport equations were solved numerically to simulate the dynamics of contrast injection into the parent arteries and IAs and then the contrast retention time (RET) was calculated. The importance of gravitational pooling of contrast agent within the aneurysm was evaluated by modeling contrast agent and blood as a mixture of two fluids with different densities and viscosities. Virtual angiograms can reproduce DSA sequences if the correct injection profile is used. RET can identify aneurysms with significant flow stagnation even when the injection profile is not known. Using a small sample of 14 IAs of which seven were previously classified as having flow stagnation, it was found that a threshold RET value of 0.46 s can successfully identify flow stagnation. CFD-based prediction of stagnation was in more than 90% agreement with independent visual DSA assessment of stagnation in a second sample of 34 IAs. While gravitational pooling prolonged contrast retention time it did not affect the predictive capabilities of RET. CFD-based virtual angiograms can detect flow stagnation in IAs and can be used to automatically identify aneurysms with flow stagnation even without including gravitational effects on contrast agents., (© 2023 John Wiley & Sons Ltd.)
- Published
- 2023
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30. Therapists who foster social identification build stronger therapeutic working alliance and have better client outcomes.
- Author
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Cruwys T, Lee GC, Robertson AM, Haslam C, Sterling N, Platow MJ, Williams E, Haslam SA, and Walter ZC
- Subjects
- Humans, Social Identification, Professional-Patient Relations, Psychotherapy, Therapeutic Alliance
- Abstract
Background: For decades we have known that therapeutic working alliance is a key contributor to client engagement and positive outcomes in therapy. However, we have made little progress in narrowing down its determinants, which is critical in supporting trainees to optimize such alliance. We make a case for the value of incorporating social psychological frameworks into models of alliance and explore the role of social identity processes in the development of therapeutic alliance., Method: Across two studies, over 500 psychotherapy clients completed validated measures of alliance, social identification with their therapist, positive therapy outcomes, and a range of client and therapist characteristics., Findings: Social identification strongly predicted alliance in both samples, whereas client and therapist characteristics showed few such associations. Alliance mediated the relationship between social identification and positive therapy outcomes. In addition, we found evidence that (a) personal control is a key psychological resource in therapy that arises from social identification, and (b) therapists who engage in identity leadership (i.e., who represent and build a social identity that they share with clients) are more likely to foster social identification and its downstream benefits., Interpretation: These data show that social identity processes are key to the emergence of working alliance. We conclude with a discussion of how recent social identity and identity leadership interventions might be adapted to train therapists in relevant identity-building skills., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2023
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31. Aspirational leaders help us change: Ingroup prototypicality enables effective group psychotherapy leadership.
- Author
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Robertson AM, Cruwys T, Stevens M, and Platow MJ
- Subjects
- Humans, Female, Longitudinal Studies, Leadership, Psychotherapy, Group
- Abstract
Objectives: Research suggests that leaders are effective when they are ingroup prototypical (represent the identity of the group they seek to lead). However, it is unclear whether leaders should represent the group's current identity ("who we are") or aspired identity ("who we want to be"). This study investigated which of these forms of prototypicality best predicted leadership effectiveness in group psychotherapy., Design: Longitudinal study., Methods: 519 questionnaire responses were obtained from 112 women attending a four-session body acceptance program. Focal measures included participant ratings of how often they thought their psychotherapy leaders and fellow group members would (a) engage in dieting thoughts and behaviours and (b) approve of dieting. Given the program's body acceptance focus, leader prototypicality was conceptualized as the difference between participants' perceptions of how often their leaders, versus group members, would diet at the start of therapy. Leadership effectiveness was conceptualized as reductions in perceived group approval of dieting across therapy. Two therapeutic outcomes were considered: body satisfaction and dieting intentions., Results: A mixed-effects repeated measures analysis indicated that group approval of dieting decreased more rapidly when participants perceived their leaders to be aspirational (thought that group leaders dieted less frequently than group members) than when they perceived them to be exemplary (thought that group leaders dieted as frequently as group members). Changes in group approval of dieting mediated the relationship between leader prototypicality and improved therapeutic outcomes., Conclusions: Findings suggest that group psychotherapy leaders may increase their effectiveness by striving to embody their group's aspired identity., (© 2022 The Authors. British Journal of Clinical Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.)
- Published
- 2023
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32. Differences Between Ruptured Aneurysms With and Without Blebs: Mechanistic Implications.
- Author
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Salimi Ashkezari SF, Mut F, Robertson AM, and Cebral JR
- Subjects
- Humans, Hemodynamics, Risk Factors, Stress, Mechanical, Aneurysm, Ruptured, Intracranial Aneurysm diagnostic imaging
- Abstract
Purpose: Blebs are known risk factors for intracranial aneurysm (IA) rupture. We analyzed differences between IAs that ruptured with blebs and those that ruptured without developing blebs to identify distinguishing characteristics among them and suggest possible mechanistic implications., Methods: Using image-based models, 25 hemodynamic and geometric parameters were compared between ruptured IAs with and without blebs (n = 673), stratified by location. Hemodynamic and geometric differences between bifurcation and sidewall aneurysms and for aneurysms at five locations were also analyzed., Results: Ruptured aneurysms harboring blebs were exposed to higher flow conditions than aneurysms that ruptured without developing blebs, and this was consistent across locations. Bifurcation aneurysms were exposed to higher flow conditions than sidewall aneurysms. They had larger maximum wall shear stress (WSS), more concentrated WSS distribution, and larger numbers of critical points than sidewall aneurysms. Additionally, bifurcation aneurysms were larger, more elongated, and had more distorted shapes than sidewall aneurysms. Aneurysm morphology was associated with aneurysm location (p < 0.01). Flow conditions were different between aneurysm locations., Conclusion: Aneurysms at different locations are likely to develop into varying morphologies and thus be exposed to diverse flow conditions that may predispose them to follow distinct pathways towards rupture with or without bleb development. This could explain the diverse rupture rates and bleb presence in aneurysms at different locations., (© 2022. The Author(s) under exclusive licence to Biomedical Engineering Society.)
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- 2023
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33. Job Demand-Control and Hypertension in African Americans and Non-African Americans.
- Author
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Raymond A, Grzywacz JG, and Robertson AM
- Subjects
- Adult, Humans, United States epidemiology, Black or African American, Research Design, Stress, Psychological epidemiology, Stress, Psychological psychology, Hypertension epidemiology
- Abstract
Objectives: The aim of this study was to determine if occupational stress is a social determinant of elevated hypertension among African Americans., Methods: Currently employed, full-time adults from the Midlife in the United States Refresher and Midlife in the United States Milwaukee Refresher studies reported data on demographics, job characteristics, and medical history., Results: African American workers reported less job control and greater physical job demands than non-African Americans. Both physical and psychological job demands were independently associated with greater odds of high blood pressure. Job strain was associated with high blood pressure and differed by race ( P < 0.05)., Conclusions: The elements of the job-demand control model differed by race and were most relevant for African Americans when exposed to high job demands and low job control. However, there was no evidence of differential vulnerability for either psychological demands, control, or physical demands for African Americans., Competing Interests: Raymond, Grzywacz, and Robertson have no relationships/conditions/circumstances that present potential conflict of interest., (Copyright © 2022 American College of Occupational and Environmental Medicine.)
- Published
- 2022
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34. A constrained mixture-micturition-growth (CMMG) model of the urinary bladder: Application to partial bladder outlet obstruction (BOO).
- Author
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Cheng F, Watton PN, Pederzani G, Kurobe M, Takaoka EI, Chapple C, Birder L, Yoshimura N, and Robertson AM
- Subjects
- Animals, Disease Models, Animal, Guanine analogs & derivatives, Male, Rats, Urinary Bladder, Urination physiology, Urodynamics, Urinary Bladder Neck Obstruction pathology
- Abstract
We present a constrained mixture-micturition-growth (CMMG) model for the bladder. It simulates bladder mechanics, voiding function (micturition) and tissue adaptations in response to altered biomechanical conditions. The CMMG model is calibrated with both in vivo and in vitro data from healthy male rat urinary bladders (cystometry, bioimaging of wall structure, mechanical testing) and applied to simulate the growth and remodeling (G&R) response to partial bladder outlet obstruction (BOO). The bladder wall is represented as a multi-layered, anisotropic, nonlinear constrained mixture. A short time scale micturition component of the CMMG model accounts for the active and passive mechanics of voiding. Over a second, longer time scale, G&R algorithms for the evolution of both cellular and extracellular constituents act to maintain/restore bladder (homeostatic) functionality. The CMMG model is applied to a spherical membrane model of the BOO bladder utilizing temporal data from an experimental male rodent model to parameterize and then verify the model. Consistent with the experimental studies of BOO, the model predicts: an initial loss of voiding capacity followed by hypertrophy of SMC to restore voiding function; bladder enlargement; collagen remodeling to maintain its role as a protective sheath; and increased voiding duration with lower average flow rate. This CMMG model enables a mechanistic approach for investigating the bladder's structure-function relationship and its adaption in pathological conditions. While the approach is illustrated with a conceptual spherical bladder model, it provides the basis for application of the CMMG model to anatomical geometries. Such a mechanistic approach has promise as an in silico tool for the rational development of new surgical and pharmacological treatments for bladder diseases such as BOO., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)
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- 2022
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35. Prediction of bleb formation in intracranial aneurysms using machine learning models based on aneurysm hemodynamics, geometry, location, and patient population.
- Author
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Salimi Ashkezari SF, Mut F, Slawski M, Cheng B, Yu AK, White TG, Woo HH, Koch MJ, Amin-Hanjani S, Charbel FT, Rezai Jahromi B, Niemelä M, Koivisto T, Frosen J, Tobe Y, Maiti S, Robertson AM, and Cebral JR
- Subjects
- Humans, Cross-Sectional Studies, Hemodynamics, Hydrodynamics, Machine Learning, Aneurysm, Ruptured epidemiology, Intracranial Aneurysm complications, Intracranial Aneurysm diagnostic imaging, Intracranial Aneurysm surgery
- Abstract
Background: Bleb presence in intracranial aneurysms (IAs) is a known indication of instability and vulnerability., Objective: To develop and evaluate predictive models of bleb development in IAs based on hemodynamics, geometry, anatomical location, and patient population., Methods: Cross-sectional data (one time point) of 2395 IAs were used for training bleb formation models using machine learning (random forest, support vector machine, logistic regression, k-nearest neighbor, and bagging). Aneurysm hemodynamics and geometry were characterized using image-based computational fluid dynamics. A separate dataset with 266 aneurysms was used for model evaluation. Model performance was quantified by the area under the receiving operating characteristic curve (AUC), true positive rate (TPR), false positive rate (FPR), precision, and balanced accuracy., Results: The final model retained 18 variables, including hemodynamic, geometrical, location, multiplicity, and morphology parameters, and patient population. Generally, strong and concentrated inflow jets, high speed, complex and unstable flow patterns, and concentrated, oscillatory, and heterogeneous wall shear stress patterns together with larger, more elongated, and more distorted shapes were associated with bleb formation. The best performance on the validation set was achieved by the random forest model (AUC=0.82, TPR=91%, FPR=36%, misclassification error=27%)., Conclusions: Based on the premise that aneurysm characteristics prior to bleb formation resemble those derived from vascular reconstructions with their blebs virtually removed, machine learning models can identify aneurysms prone to bleb development with good accuracy. Pending further validation with longitudinal data, these models may prove valuable for assessing the propensity of IAs to progress to vulnerable states and potentially rupturing., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)
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- 2022
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36. Global dataset of species-specific inland recreational fisheries harvest for consumption.
- Author
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Embke HS, Nyboer EA, Robertson AM, Arlinghaus R, Akintola SL, Atessahin T, Badr LM, Baigun C, Basher Z, Beard TD Jr, Boros G, Bower SD, Cooke SJ, Cowx IG, Franco A, Gaspar-Dillanes MT, Granada VP, Hart RJ, Heinsohn CR, Jalabert V, Kapusta A, Krajč T, Koehn JD, Lopes G, Lyach R, Magqina T, Milardi M, Nattabi J, Nyaboke H, Phang S, Potts WM, Ribeiro F, Mercado-Silva N, Sreenivasan N, Thorpe A, Treer T, Ustups D, Weyl OLF, Wood LE, Zengin M, and Lynch AJ
- Subjects
- Animals, Conservation of Natural Resources, Ecosystem, Fishes, Species Specificity, Fisheries
- Abstract
Inland recreational fisheries, found in lakes, rivers, and other landlocked waters, are important to livelihoods, nutrition, leisure, and other societal ecosystem services worldwide. Although recreationally-caught fish are frequently harvested and consumed by fishers, their contribution to food and nutrition has not been adequately quantified due to lack of data, poor monitoring, and under-reporting, especially in developing countries. Beyond limited global harvest estimates, few have explored species-specific harvest patterns, although this variability has implications for fisheries management and food security. Given the continued growth of the recreational fishery sector, understanding inland recreational fish harvest and consumption rates represents a critical knowledge gap. Based on a comprehensive literature search and expert knowledge review, we quantified multiple aspects of global inland recreational fisheries for 81 countries spanning ~192 species. For each country, we assembled recreational fishing participation rate and estimated species-specific harvest and consumption rate. This dataset provides a foundation for future assessments, including understanding nutritional and economic contributions of inland recreational fisheries., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)
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- 2022
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37. Identification of Small, Regularly Shaped Cerebral Aneurysms Prone to Rupture.
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Salimi Ashkezari SF, Mut F, Slawski M, Jimenez CM, Robertson AM, and Cebral JR
- Subjects
- Cerebral Angiography, Cross-Sectional Studies, Hemodynamics, Humans, Hydrodynamics, Risk Factors, Aneurysm, Ruptured diagnostic imaging, Intracranial Aneurysm diagnostic imaging
- Abstract
Background and Purpose: Many small, regularly shaped cerebral aneurysms rupture; however, they usually receive a low score based on current risk-assessment methods. Our goal was to identify patient and aneurysm characteristics associated with rupture of small, regularly shaped aneurysms and to develop and validate predictive models of rupture in this aneurysm subpopulation., Materials and Methods: Cross-sectional data from 1079 aneurysms smaller than 7 mm with regular shapes (without blebs) were used to train predictive models for aneurysm rupture using machine learning methods. These models were based on the patient population, aneurysm location, and hemodynamic and geometric characteristics derived from image-based computational fluid dynamics models. An independent data set with 102 small, regularly shaped aneurysms was used for validation., Results: Adverse hemodynamic environments characterized by strong, concentrated inflow jets, high speed, complex and unstable flow patterns, and concentrated, oscillatory, and heterogeneous wall shear stress patterns were associated with rupture in small, regularly shaped aneurysms. Additionally, ruptured aneurysms were larger and more elongated than unruptured aneurysms in this subset. A total of 5 hemodynamic and 6 geometric parameters along with aneurysm location, multiplicity, and morphology, were used as predictive variables. The best machine learning rupture prediction-model achieved a good performance with an area under the curve of 0.84 on the external validation data set., Conclusions: This study demonstrated the potential of using predictive machine learning models based on aneurysm-specific hemodynamic, geometric, and anatomic characteristics for identifying small, regularly shaped aneurysms prone to rupture., (© 2022 by American Journal of Neuroradiology.)
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- 2022
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38. Parenting, Pesticides and Adolescent Psychological Adjustment: A Brief Report.
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Grzywacz JG, Belden JB, Robertson AM, Hernandez DC, Carlos Chavez FL, and Merten MJ
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- Adaptation, Psychological, Adolescent, Depression epidemiology, Emotional Adjustment, Humans, Parent-Child Relations, Parenting, Adolescent Behavior, Pesticides
- Abstract
Pesticides used to control insects, such as pyrethroids, are neurotoxicants, yet adolescent researchers often overlook their potential role in adolescent psychological adjustment. This brief report is guided by bioecological theory and considers the possible independent and interactive effects of environmental pyrethroid pesticide exposure for adolescent depressive symptoms. Self-reported adolescent appraisals of the parent-child relationship and depressive symptoms were obtained from a convenience sample of impoverished, predominantly Latino urban youth ( n = 44). Exposure to environmental pyrethroids was obtained from wipe samples using a standardized protocol. Parent-adolescent conflict was higher in households with bifenthrin than those without, and adolescent depressive symptoms were elevated in homes where cypermethrin was detected. In addition, the presence of bifenthrin in the home attenuated the protective effects of parental involvement on adolescent depressive symptoms. The current results suggest that adolescent mental health researchers must consider the synergistic combinations of adolescents' environments' physical and social features. Given the endemic presence of pesticides and their neurotoxic function, pesticide exposure may demand specific attention.
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- 2022
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39. Abdominal hereditary angio-oedema caught on magnetic resonance imaging.
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Siow MTL, Robertson AM, Ghurye RR, and Blaker PA
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- Abdominal Pain etiology, Adolescent, Ascites, Edema diagnostic imaging, Edema etiology, Female, Humans, Magnetic Resonance Imaging, Angioedemas, Hereditary diagnostic imaging
- Abstract
A 17-year-old woman presented with a 3-year history of recurrent, severe abdominal pain with spontaneous resolution within a few days. An ultrasound revealed nothing more than free fluid within the pelvis. An MRI of the small bowel was done within 24 hours of abdominal pain onset, which revealed extensive submucosal oedema associated with moderate volume ascites. A repeat MRI of the small bowel after 72 hours showed near-complete resolution of these changes. Checking C1 inhibitor levels confirmed a diagnosis of hereditary angio-oedema with an abdominal presentation. This is a rare cause of recurrent abdominal pain and, to our knowledge, the first case in which MR images have been obtained during and after an acute attack., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2021
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40. Hemodynamics in aneurysm blebs with different wall characteristics.
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Salimi Ashkezari SF, Mut F, Chung BJ, Yu AK, Stapleton CJ, See AP, Amin-Hanjani S, Charbel FT, Rezai Jahromi B, Niemelä M, Frösen J, Maiti S, Robertson AM, and Cebral JR
- Subjects
- Female, Humans, Male, Imaging, Three-Dimensional methods, Microsurgery methods, Risk Factors, Stress, Mechanical, Aneurysm, Ruptured diagnostic imaging, Aneurysm, Ruptured physiopathology, Aneurysm, Ruptured surgery, Hemodynamics physiology, Hydrodynamics, Intracranial Aneurysm diagnostic imaging, Intracranial Aneurysm physiopathology, Intracranial Aneurysm surgery
- Abstract
Background: Blebs are important secondary structures of intracranial aneurysms associated with increased rupture risk and can affect local wall stress and hemodynamics. Mechanisms of bleb development and evolution are not clearly understood. We investigate the relationship between blebs with different wall characteristics and local hemodynamics and rupture sites., Methods: Blebs with different wall appearances in intra-operative videos were analyzed with image-based computational fluid dynamics. Thin red blebs were compared against thick atherosclerotic/hyperplastic white/yellow blebs. Rupture points were identified in videos of ruptured aneurysms harboring blebs., Results: Thin blebs tended to be closer to the inflow than atherosclerotic blebs of the same aneurysm (P=0.0234). Blebs near the inflow had higher velocity (P=0.0213), vorticity (P=0.0057), shear strain rate (P=0.0084), wall shear stress (WSS) (P=0.0085), and WSS gradient (P=0.0151) than blebs far from the inflow. In a subset of 12 ruptured aneurysms harboring blebs, rupture points were associated with thin blebs in 42% of aneurysms, atherosclerotic blebs in 25%, and were away from blebs in the remaining 33%., Conclusions: Not all blebs are equal; some have thin translucent walls while others have thick atherosclerotic walls. Thin blebs tend to be located closer to the inflow than atherosclerotic blebs. Blebs near the inflow are exposed to stronger flows with higher and spatially variable WSS than blebs far from the inflow which tend to have uniformly lower WSS. Aneurysms can rupture at thin blebs, atherosclerotic blebs, and even away from blebs. Further study of wall failure in aneurysms with different bleb types is needed., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2021
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41. Regional Aneurysm Wall Enhancement is Affected by Local Hemodynamics: A 7T MRI Study.
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Hadad S, Mut F, Chung BJ, Roa JA, Robertson AM, Hasan DM, Samaniego EA, and Cebral JR
- Subjects
- Cerebral Angiography methods, Humans, Male, Stress, Mechanical, Hemodynamics physiology, Intracranial Aneurysm diagnostic imaging, Intracranial Aneurysm pathology, Magnetic Resonance Imaging methods
- Abstract
Background and Purpose: Aneurysm wall enhancement has been proposed as a biomarker for inflammation and instability. However, the mechanisms of aneurysm wall enhancement remain unclear. We used 7T MR imaging to determine the effect of flow in different regions of the wall., Materials and Methods: Twenty-three intracranial aneurysms imaged with 7T MR imaging and 3D angiography were studied with computational fluid dynamics. Local flow conditions were compared between aneurysm wall enhancement and nonenhanced regions. Aneurysm wall enhancement regions were subdivided according to their location on the aneurysm and relative to the inflow and were further compared., Results: On average, wall shear stress was lower in enhanced than in nonenhanced regions ( P = .05). Aneurysm wall enhancement regions at the neck had higher wall shear stress gradients ( P = .05) with lower oscillations ( P = .05) than nonenhanced regions. In contrast, aneurysm wall enhancement regions at the aneurysm body had lower wall shear stress ( P = .01) and wall shear stress gradients ( P = .008) than nonenhanced regions. Aneurysm wall enhancement regions far from the inflow had lower wall shear stress ( P = .006) than nonenhanced regions, while aneurysm wall enhancement regions close to the inflow tended to have higher wall shear stress than the nonenhanced regions, but this association was not significant., Conclusions: Aneurysm wall enhancement regions tend to have lower wall shear stress than nonenhanced regions of the same aneurysm. Moreover, the association between flow conditions and aneurysm wall enhancement seems to depend on the location of the region on the aneurysm sac. Regions at the neck and close to the inflow tend to be exposed to higher wall shear stress and wall shear stress gradients. Regions at the body, dome, or far from the inflow tend to be exposed to uniformly low wall shear stress and have more aneurysm wall enhancement., (© 2021 by American Journal of Neuroradiology.)
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- 2021
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42. Blebs in intracranial aneurysms: prevalence and general characteristics.
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Salimi Ashkezari SF, Detmer FJ, Mut F, Chung BJ, Yu AK, Stapleton CJ, See AP, Amin-Hanjani S, Charbel FT, Rezai Jahromi B, Niemelä M, Frösen J, Zhou J, Maiti S, Robertson AM, and Cebral JR
- Subjects
- Adult, Aged, Aged, 80 and over, Female, Humans, Male, Middle Aged, Carotid Artery, Internal physiopathology, Cerebral Angiography methods, Hypertension diagnostic imaging, Hypertension epidemiology, Hypertension surgery, Prevalence, Risk Factors, Smoking adverse effects, Smoking epidemiology, Aneurysm, Ruptured diagnostic imaging, Aneurysm, Ruptured epidemiology, Aneurysm, Ruptured surgery, Intracranial Aneurysm diagnostic imaging, Intracranial Aneurysm epidemiology, Intracranial Aneurysm surgery
- Abstract
Background: Blebs are rupture risk factors in intracranial aneurysms (IAs), but their prevalence, distribution, and associations with clinical factors as well as their causes and effects on aneurysm vulnerability remain unclear., Methods: A total of 122 blebs in 270 IAs selected for surgery were studied using patient-specific vascular reconstructions from 3D angiographic images. Bleb geometry, location on the aneurysm, and frequency of occurrence in aneurysms at different locations were analyzed. Associations between gender, age, smoking, hypertension, hormone therapy, dental infection, and presence of blebs were investigated., Results: Of all aneurysms with blebs, 77% had a single bleb and 23% had multiple blebs. Only 6% of blebs were at the neck, while 46% were in the body and 48% in the dome. Aneurysms with blebs were larger (p<0.0001), more elongated (p=0.0002), and with wider necks than aneurysms without blebs. Bleb presence was associated with dental infection (p=0.0426) and negatively associated with hormone therapy (p=0.0426) in women. Anterior and posterior communicating arteries had larger percentages of aneurysms with blebs than internal carotid arteries. Patients with a history of hypertension tended to have a larger percentage of aneurysms with blebs. However, these trends did not reach significance in this sample., Conclusions: Blebs are common in IAs, and most aneurysms harboring blebs have a single bleb. Blebs in the aneurysm neck are rare, but they are equally common in the body and dome. The presence of blebs in IAs was associated with dental infection, and negatively associated with hormone replacement therapy., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2021
- Full Text
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43. Hemodynamic conditions that favor bleb formation in cerebral aneurysms.
- Author
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Salimi Ashkezari SF, Mut F, Chung BJ, Robertson AM, and Cebral JR
- Subjects
- Adult, Female, Humans, Male, Middle Aged, Hydrodynamics, Imaging, Three-Dimensional methods, Risk Factors, Stress, Mechanical, Aneurysm, Ruptured diagnostic imaging, Aneurysm, Ruptured physiopathology, Aneurysm, Ruptured surgery, Hemodynamics physiology, Intracranial Aneurysm diagnostic imaging, Intracranial Aneurysm physiopathology, Intracranial Aneurysm surgery
- Abstract
Background: Although it is generally believed that blebs represent weaker spots in the walls of intracranial aneurysms (IAs), it is largely unknown which aneurysm characteristics favor their development., Objective: To investigate possible associations between aneurysm hemodynamic and geometric characteristics and the development of blebs in intracranial aneurysms., Methods: A total of 270 IAs in 199 patients selected for surgical clipping were studied. Blebs were visually identified and interactively marked on patient-specific vascular models constructed from presurgical images. Blebs were then deleted from the vascular reconstruction to approximate the aneurysm before bleb formation. Computational fluid dynamics studies were performed in these models and in cases without blebs. Hemodynamic and geometric characteristics of aneurysms with and without blebs were compared., Results: A total of 173 aneurysms had no blebs, while 97 aneurysms had a total of 122 blebs. Aneurysms favoring bleb formation had stronger (p<0.0001) and more concentrated inflow jets (p<0.0001), higher flow velocity (p=0.0061), more complex (p<0.0001) and unstable (p=0.0157) flow patterns, larger maximum wall shear stress (WSS; p<0.0001), more concentrated (p=0.0005) and oscillatory (p=0.0004) WSS distribution, and a more heterogeneous WSS field (p<0.0001), than aneurysms without blebs. They were also larger (p<0.0001), more elongated (p<0.0001), had wider necks (p=0.0002), and more distorted and irregular shapes (p<0.0001)., Conclusions: Strong and concentrated inflow jets, high-speed, complex, and unstable flow patterns, and concentrated, oscillatory, and heterogeneous WSS patterns favor the formation of blebs in IAs. Blebs are more likely to form in large, elongated, and irregularly shaped aneurysms. These adverse characteristics could be considered signs of aneurysm instability when evaluating aneurysms for conservative observation or treatment., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2021
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- View/download PDF
44. Analysis of hemodynamic changes from aneurysm inception to large sizes.
- Author
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Salimi Ashkezari SF, Mut F, Chung BJ, Robertson AM, Frösen J, and Cebral JR
- Subjects
- Hemodynamics, Humans, Hydrodynamics, Stress, Mechanical, Intracranial Aneurysm diagnostic imaging
- Abstract
While previous studies have identified many risk factors for the progression and rupture of cerebral aneurysms, the changes in aneurysm flow characteristics during its evolution are not fully understood. This work analyzes the changes in the aneurysm hemodynamic environment from its initial development to later stages when the aneurysm has substantially enlarged. A total of 88 aneurysms at four locations were studied with image based computational fluid dynamics (CFD). Two synthetic sequences representing the aneurysm geometry at three earlier stages were generated by shrinking the aneurysm sac while keeping the neck fixed or shrinking the neck simultaneously. The flow conditions were then quantitatively compared between these two modes of evolution. As aneurysms enlarged, the inflow rate increased in growing neck sequences, but decreased in fixed neck sequences. The inflow jet became more concentrated in both sequences. The mean aneurysm flow velocity and wall shear stress decreased in both sequences, but they decreased faster in enlarging aneurysms if the neck was fixed. Additionally, the intra-aneurysmal flows became more complex and more unstable, wall shear stress distribution became more oscillatory, and the area under low wall shear stress increased for both sequences. The evolution of flow characteristics of aneurysms with fixed and growing necks are different. The observed trends suggest that fixed neck aneurysms may evolve towards a flow environment characteristic of stable aneurysms faster than aneurysms with growing necks, which could also evolve towards a more disfavorable environment., (© 2020 John Wiley & Sons, Ltd.)
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- 2021
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45. Adaptive Remodeling in the Elastase-induced Rabbit Aneurysms.
- Author
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Sang C, Kallmes DF, Kadirvel R, Durka MJ, Ding YH, Dai D, Watkins SC, and Robertson AM
- Abstract
Background: Rupture of brain aneurysms is associated with high fatality and morbidity rates. Through remodeling of the collagen matrix, many aneurysms can remain unruptured for decades, despite an enlarging and evolving geometry., Objective: Our objective was to explore this adaptive remodeling for the first time in an elastase induced aneurysm model in rabbits., Methods: Saccular aneurysms were created in 22 New Zealand white rabbits and remodeling was assessed in tissue harvested 2, 4, 8 and 12 weeks after creation., Results: The intramural principal stress ratio doubled after aneurysm creation due to increased longitudinal loads, triggering a remodeling response. A distinct wall layer with multi-directional collagen fibers developed between the media and adventitia as early as 2 weeks, and in all cases by 4 weeks with an average thickness of 50.6 ± 14.3 μm. Collagen fibers in this layer were multi-directional ( AI = 0.56 ± 0.15) with low tortuosity (1.08 ± 0.02) compared with adjacent circumferentially aligned medial fibers (AI = 0.78 ± 0.12) and highly tortuous adventitial fibers (1.22 ± 0.03). A second phase of remodeling replaced circumferentially aligned fibers in the inner media with longitudinal fibers. A structurally motivated constitutive model with both remodeling modes was introduced along with methodology for determining material parameters from mechanical testing and multiphoton imaging., Conclusions: A new mechanism was identified by which aneurysm walls can rapidly adapt to changes in load, ensuring the structural integrity of the aneurysm until a slower process of medial reorganization occurs. The rabbit model can be used to evaluate therapies to increase aneurysm wall stability., Competing Interests: Conflict of Interst: The authors declare no competing interests.
- Published
- 2021
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46. Effect of macro-calcification on the failure mechanics of intracranial aneurysmal wall tissue.
- Author
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Fortunato RN, Robertson AM, Sang C, Duan X, and Maiti S
- Abstract
Background: Calcification was recently found to be present in the majority of cerebral aneurysms, though how calcification and the presence or absence of co-localized lipid pools affect failure properties is still unknown., Objective: The primary objective is to quantify the biomechanical effect of a macro-calcification with surrounding Near-Calcification Region (NCR) of varying mechanical properties on tissue failure behavior., Methods: We utilized a structurally informed finite element model to simulate pre-failure and failure behavior of a human cerebral tissue specimen modeled as a composite containing a macro-calcification and surrounding NCR, embedded in a fiber matrix composite. Data from multiple imaging modalities was combined to quantify the collagen organization and calcification geometry. An idealized parametric model utilizing the calibrated model was used to explore the impact of NCR properties on tissue failure., Results: Compared to tissue without calcification, peak stress was reduced by 82% and 49% for low modulus (representing lipid pool) and high modulus (simulating increase in calcification size) of the NCR, respectively. Failure process strongly depended on NCR properties with lipid pools blunting the onset of complete failure. When the NCR was calcified, the sample was able to sustain larger overall stress, however the failure process was abrupt with nearly simultaneous failure of the loaded fibers., Conclusions: Failure of calcified vascular tissue is strongly influenced by the ultrastructure in the vicinity of the calcification. Computational modeling of failure in fibrous soft tissues can be used to understand how pathological changes impact the tissue failure process, with potentially important clinical implications.
- Published
- 2021
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47. New Mexico Permian Basin Measured Well Pad Methane Emissions Are a Factor of 5-9 Times Higher Than U.S. EPA Estimates.
- Author
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Robertson AM, Edie R, Field RA, Lyon D, McVay R, Omara M, Zavala-Araiza D, and Murphy SM
- Subjects
- Laboratories, Natural Gas analysis, New Mexico, Air Pollutants analysis, Methane analysis
- Abstract
Methane emission fluxes were estimated for 71 oil and gas well pads in the western Permian Basin (Delaware Basin), using a mobile laboratory and an inverse Gaussian dispersion method (OTM 33A). Sites with emissions that were below detection limit (BDL) for OTM 33A were recorded and included in the sample. Average emission rate per site was estimated by bootstrapping and by maximum likelihood best log-normal fit. Sites had to be split into "complex" (sites with liquid storage tanks and/or compressors) and "simple" (sites with only wellheads/pump jacks/separators) categories to achieve acceptable log-normal fits. For complex sites, the log-normal fit depends heavily on the number of BDL sites included. As more BDL sites are included, the log-normal distribution fit to the data is falsely widened, overestimating the mean, highlighting the importance of correctly characterizing low end emissions when using log-normal fits. Basin-wide methane emission rates were estimated for the production sector of the New Mexico portion of the Permian and range from ∼520 000 tons per year, TPY (bootstrapping, 95% CI: 300 000-790 000) to ∼610 000 TPY (log-normal fit method, 95% CI: 330 000-1 000 000). These estimates are a factor of 5.5-9.0 times greater than EPA National Emission Inventory (NEI) estimates for the region.
- Published
- 2020
- Full Text
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48. Purine nucleoside phosphorylase inhibition ameliorates age-associated lower urinary tract dysfunctions.
- Author
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Birder LA, Wolf-Johnston A, Wein AJ, Cheng F, Grove-Sullivan M, Kanai AJ, Watson AM, Stoltz D, Watkins SC, Robertson AM, Newman D, Dmochowski RR, and Jackson EK
- Subjects
- Aging drug effects, Animals, Disease Models, Animal, Female, Guanine pharmacology, Humans, Male, Purine-Nucleoside Phosphorylase antagonists & inhibitors, Rats, Urinary Bladder drug effects, Urinary Bladder pathology, Urologic Diseases genetics, Urologic Diseases pathology, Aging genetics, Guanine analogs & derivatives, Purine-Nucleoside Phosphorylase genetics, Urologic Diseases drug therapy
- Abstract
In the aging population, lower urinary tract (LUT) dysfunction is common and often leads to storage and voiding difficulties classified into overlapping symptom syndromes. Despite prevalence and consequences of these syndromes, LUT disorders continue to be undertreated simply because there are few therapeutic options. LUT function and structure were assessed in aged (>25 months) male and female Fischer 344 rats randomized to oral treatment with a purine nucleoside phosphorylase (PNPase inhibitor) 8-aminoguanine (8-AG) or vehicle for 6 weeks. The bladders of aged rats exhibited multiple abnormalities: tactile insensitivity, vascular remodeling, reduced collagen-fiber tortuosity, increased bladder stiffness, abnormal smooth muscle morphology, swelling of mitochondria, and increases in urodamaging purine metabolites. Treatment of aged rats with 8-AG restored all evaluated histological, ultrastructural, and physiological abnormalities toward that of a younger state. 8-AG is an effective treatment that ameliorates key age-related structural and physiologic bladder abnormalities. Because PNPase inhibition blocks metabolism of inosine to hypoxanthine and guanosine to guanine, likely uroprotective effects of 8-AG are mediated by increased bladder levels of uroprotective inosine and guanosine and reductions in urodamaging hypoxanthine and xanthine. These findings demonstrate that 8-AG has translational potential for treating age-associated LUT dysfunctions and resultant syndromes in humans.
- Published
- 2020
- Full Text
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49. Off-Site Flux Estimates of Volatile Organic Compounds from Oil and Gas Production Facilities Using Fast-Response Instrumentation.
- Author
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Edie R, Robertson AM, Soltis J, Field RA, Snare D, Burkhart MD, and Murphy SM
- Subjects
- Environmental Monitoring, Wyoming, Air Pollutants, Ozone, Volatile Organic Compounds
- Abstract
Flux estimates of volatile organic compounds (VOCs) from oil and gas (O&G) production facilities are fundamental in understanding hazardous air pollutant concentrations and ozone formation. Previous off-site emission estimates derive fluxes by ratioing VOCs measured in canisters to methane fluxes measured in the field. This study uses the Environmental Protection Agency's Other Test Method 33A (OTM 33A) and a fast-response proton transfer reaction mass spectrometer to make direct measurements of VOC emissions from O&G facilities in the Upper Green River Basin, Wyoming. We report the first off-site direct flux estimates of benzene, toluene, ethylbenzene, and xylenes from upstream O&G production facilities and find that these estimates can vary significantly from flux estimates derived using both the canister ratio technique and from the emission inventory. The 32 OTM 33A flux estimates had arithmetic mean (and 95% CI) as follows: benzene 17.83 (0.22, 98.05) g/h, toluene 34.43 (1.01, 126.76) g/h, C8 aromatics 37.38 (1.06, 225.34) g/h, and methane 2.3 (1.7, 3.1) kg/h. A total of 20% of facilities measured accounted for ∼67% of total BTEX emissions. While this heavy tail is less dramatic than previous observations of methane in other basins, it is more prominent than that predicted by the emission inventory.
- Published
- 2020
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50. Correction to: The unexplained success of stentplasty vasospasm treatment : Insights using Mechanistic Mathematical Modeling.
- Author
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Bhogal P, Pederzani G, Grytsan A, Loh Y, Brouwer PA, Andersson T, Gundiah N, Robertson AM, Watton PN, and Söderman M
- Abstract
Correction to: Clin Neuroradiol 2019 https://doi.org/10.1007/s00062-019-00776-2 The original version of this article unfortunately contained a mistake. The Acknowledgements were missing. The correct information is given ….
- Published
- 2019
- Full Text
- View/download PDF
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