269 results on '"Robertson, M. D."'
Search Results
102. A low energy ion beam assisted deposition technique for realizing iso-type SiGe/Si hetero-interface diodes
- Author
-
Mohajerzadeh, S., Selvakumar, C. R., Brodie, D. E., Robertson, M. D., and Corbett, J. M.
- Published
- 1996
- Full Text
- View/download PDF
103. Preparation of PCDE
- Author
-
ROCKWELL INTERNATIONAL CANOGA PARK CA ROCKETDYNE DIV, Gunderloy, F. C., Tuffly, B. L., Thompson, W. W., West, C. L., Robertson, M. D., ROCKWELL INTERNATIONAL CANOGA PARK CA ROCKETDYNE DIV, Gunderloy, F. C., Tuffly, B. L., Thompson, W. W., West, C. L., and Robertson, M. D. more...
- Abstract
Alternate processes for preparing PCDE, poly 1-cyano, 1-difluoramino ethylene oxide, have been explored. Difluoramination of DEPECH, poly-2,3 epoxy propane, in heterogeneous gas-liquid reactions near atmospheric pressure have been studied as possible alternatives to the homogeneous high-pressure (400 psig) reaction in acetone solvent currently used for the manufacture of PBEP (the PCDE precursor). Other solvents and mixed solvents have been tested as reaction media. Difluoramine generation by hydrolysis of difluorosulfamic acid was studied. Difluoramination does occur using the alternative processes, but addition of the NF2 is less than half the theoretical amount. No solvent reaction media was found that could dissolve both DEPECH and tetrafluorohydrazine in sufficient concentrations to drive the reaction to completion at near atmospheric pressures. Reactions have been conducted in vented continuous flow apparatus as well as in a closed reaction vessel, and have been followed using infrared spectroscopy, gas-liquid chromatography and elemental analyses. more...
- Published
- 1976
104. Misleading conclusions on effects of resistant starch due to inappropriate formulation of controls, inadequate statistical power, and anomalies in the in vitro methods.
- Author
-
Keenan, Michael J., Martin, Roy J., Robertson, M. D., Aryana, Kayanush J., Witwer, Rhonda, and Warshaw, Hope
- Subjects
STARCH metabolism ,RESEARCH methodology ,BLOOD sugar ,GLUCANS ,GRAIN ,MILK proteins ,SNACK foods ,DIETARY sucrose - Published
- 2017
- Full Text
- View/download PDF
105. Cimetidine and therapy of rodent tumours
- Author
-
Hannant, D, primary, James, K, additional, Bolton, R E, additional, Robertson, M D, additional, and Milne, I, additional
- Published
- 1982
- Full Text
- View/download PDF
106. Serum 25-hydroxy vitamin D in coalworkers and surface workers in winter.
- Author
-
Shuster, S, primary, Chadwick, L, additional, Afacan, A S, additional, and Robertson, M D, additional
- Published
- 1982
- Full Text
- View/download PDF
107. Serum 25-hydroxy vitamin D in surface and underground coalminers.
- Author
-
Shuster, S, primary, Chadwick, L, additional, Afacan, A S, additional, and Robertson, M D, additional
- Published
- 1981
- Full Text
- View/download PDF
108. Undesirable sounds
- Author
-
Best, W J, primary and Robertson, M D, additional
- Published
- 1971
- Full Text
- View/download PDF
109. Severe Anaemia Associated with Myelosclerosis, Responding to Splenectomy
- Author
-
Robertson, M D J, primary and Gottlieb, B, additional
- Published
- 1966
- Full Text
- View/download PDF
110. Science in the service of man?
- Author
-
Robertson, M D, primary
- Published
- 1971
- Full Text
- View/download PDF
111. The impact of body mass index status on appetite responses and food intake following acute consumption of resistant starch.
- Author
-
Al-Mana, N. M. and Robertson, M. D.
- Published
- 2018
- Full Text
- View/download PDF
112. Different methods of cooking starchy-carbohydrate food and its impact on postprandial lipid metabolism.
- Author
-
Oraee, R., Alzaabi, A., Robertson, M. D., and Fielding, B. A.
- Published
- 2017
- Full Text
- View/download PDF
113. The comparative effects of intermittent versus continuous energy restriction on anthropometry and cardiometabolic disease risk markers in obese patients utilizing weight loss support services provided by an NHS tier 3 weight management service.
- Author
-
Antoni, R., Johnston, K. L., Steele, C., Carter, D., Robertson, M. D., and Capehorn, M.
- Published
- 2017
- Full Text
- View/download PDF
114. TEM Characterization of Epitaxial MnSi Films Grown on (111) Si Substrates.
- Author
-
Robertson, M. D., Karhu, E. A., and Monchesky, T. L.
- Subjects
TRANSMISSION electron microscopy - Abstract
Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010. [ABSTRACT FROM PUBLISHER]
- Published
- 2010
- Full Text
- View/download PDF
115. Investigation into the acute effects of intermittent energy restriction on postprandial substrate metabolism.
- Author
-
Antoni, R., Johnston, K. L., Collins, A., and Robertson, M. D.
- Published
- 2016
- Full Text
- View/download PDF
116. Strain contrast of GaNyAs1−y (y = 0.029 and 0.045) epitaxial layers on (100) GaAs substrates in annular dark field images.
- Author
-
Wu, X., Robertson, M. D., Gupta, J. A., and Baribeau, J-M
- Published
- 2008
- Full Text
- View/download PDF
117. Severe Anaemia Associated with Myelosclerosis, Responding to Splenectomy
- Author
-
Robertson, M D J and Gottlieb, B
- Published
- 1966
- Full Text
- View/download PDF
118. Determination of elastic strains in epitaxial layers by HREM
- Author
-
Robertson, M. D., Currie, J. E., Corbett, J. M., and Webb, J. B.
- Published
- 1995
- Full Text
- View/download PDF
119. Responsibility analysis: A methodology to study the effects of drugs in driving
- Author
-
Robertson, M. D. and Drummer, O. H.
- Published
- 1994
- Full Text
- View/download PDF
120. High-performance liquid chromatographic procedure for the measurement of nitrobenzodiazepines and their 7-amino metabolites in blood
- Author
-
Robertson, M. D. and Drummer, O. H.
- Published
- 1995
- Full Text
- View/download PDF
121. Examining the acute effects of exercise intensity on subsequent appetite, food intake, resting energy expenditure and fat oxidation
- Author
-
Shamlan, G., Robertson, M. D., and Collins, A.
- Subjects
613.7 - Abstract
Energy balance is important for weight maintenance with exercise having documented physiological, behavioural, and appetite effects. Exercise is known to acutely influence appetite but evidence for an independent effect of intensity is lacking. The purpose of this dissertation was to investigate the role of exercise intensity on appetite and energy intake (EI), energy expenditure (EE), and the metabolic effects of exercise intensity per se in lean and overweight individuals and to determine whether there was influence of gender or differences between groups. Forty healthy volunteers (30 lean and 10 overweight) undertook 2 periods of exercise matched for energy cost, (i) 8 repeated 60 second bouts of cycling at 95% VO2 max; high intensity exercise (HI) and (ii) 30 minutes of continuous cycling, at a fixed cadence, at 50% VO2 max; low intensity exercise (LI) in a randomised cross-over design. Satiety to a standard meal was assessed subjectively using visual analogue scales. Ad libitum intake was measured 3-h post-breakfast and for 2 days post-exercise. EE and fat oxidation were measured every 30 mins post-exercise. The results showed that in the lean group relative to LI, HI suppressed prospective food consumption, increased EE (P=0.001), fatty acid (NEFA) utilisation (P=0.004) and fat oxidation (P<0.001), but did not affect appetite, EI, plasma glucose, insulin, GLP-1 or lipid levels post-exercise. There was a differential effect of gender on prospective food consumption and NEFA response post-exercise. HI increased EE and fat oxidation post-exercise for men. In the overweight individuals, HI did not differ from LI in terms of appetite, GLP-1, glucose, insulin, lipid or NEFA levels, with no difference in EI, EE and fat oxidation post-exercise. In conclusion, there are different consequences of exercise intensity in short-term control of energy balance depending on BMI and gender; our results support the need for longer term intervention to test these mechanisms. more...
- Published
- 2016
122. The effects of coffee on glucose metabolism
- Author
-
Robertson, Tracey M., Robertson, M. D., and Clifford, M. N.
- Subjects
612.3 - Abstract
It has been suggested that coffee drinking may confer a beneficial effect on health by reducing the risk of developing Type 2 Diabetes Mellitus (T2DM) and indeed there is much epidemiological evidence for a reduced incidence of T2DM in habitual coffee drinkers. However, many acute studies have reported a temporary worsening in postprandial glycaemia following caffeinated coffee (CC) consumption. Varied methodologies have been employed by these studies with many giving their participants large doses of coffee. In the acute studies conducted for this thesis, a single serving of CC increased the postprandial glycaemic response more than control (p=0.008), with no apparent dose-response effect. Furthermore, a single serving of decaffeinated coffee (DC) consumed in the morning, produced no effect on postprandial glycaemia, although a trend was observed for a reduction in the postprandial glucose peak (p=0.060) when DC was consumed at lunchtime. The majority of longer-term investigations have recruited habitual coffee drinkers who are likely to have already obtained any potential benefits of coffee consumption. The longer-term intervention reported in this thesis found no overall effects of twelve weeks of CC drinking on glucose and lipid metabolism in coffee-naïve individuals. However, differences were observed between fast and slow caffeine metabolisers when the analysis was split by phenotype. The fast caffeine metabolisers displayed a lower postprandial glucose response (p=0.019) and greater NEFA suppression (p=0.001) at baseline. Furthermore, significant interaction effects were observed between visit and phenotype for postprandial glucose (p=0.048) and NEFA (p=0.019), with the intervention producing an apparent increase in postprandial glycaemia in fast metabolisers and reduced NEFA suppression in slow metabolisers. In conclusion, no evidence was found for a beneficial effect of coffee drinking on glucose and lipid metabolism in the general population, however, individual differences in response to longer-term coffee drinking were observed which warrant further investigation. more...
- Published
- 2016
123. Variation of LDL cholesterol in response to the replacement of saturated with unsaturated fatty acids: a nonrandomized, sequential dietary intervention; the Reading, Imperial, Surrey, Saturated fat Cholesterol Intervention ("RISSCI"-1) study.
- Author
-
Koutsos A, Griffin BA, Antoni R, Ozen E, Sellem L, Wong G, Ayyad H, Fielding BA, Robertson MD, Swann J, Jackson KG, and Lovegrove JA
- Subjects
- Humans, Male, Middle Aged, Adult, Cardiovascular Diseases prevention & control, Diet, Dietary Fats administration & dosage, Cholesterol, LDL blood, Fatty Acids, Unsaturated administration & dosage, Fatty Acids
- Abstract
Background: Serum low density lipoprotein (LDL) cholesterol shows marked interindividual variation in response to the replacement of saturated fatty acids (SFAs) with unsaturated fatty acids (UFAs)., Objectives: To demonstrate the efficacy of United Kingdom guidelines for exchanging dietary SFAs for UFAs, to reduce serum LDL cholesterol and other cardiovascular disease (CVD) risk factors, and to identify determinants of the variability in LDL cholesterol response., Methods: Healthy males (n = 109, mean ± SD age 48 ± 11 y; BMI 25.1 ± 3.3 kg/m
2 ), consumed a higher-SFA/lower-UFA diet for 4 wk, followed by an isoenergetic, lower-SFA/higher-UFA diet for 4 wk (achieved intakes SFA:UFA as % total energy 19.1:14.8 and 8.9:24.5, respectively). Serum LDL cholesterol, CVD risk markers, peripheral blood mononuclear cell (PBMC) gene expression, and dietary intakes were assessed at baseline and the end of each diet., Results: Transition from a higher-SFA/lower-UFA to a lower-SFA/higher-UFA diet significantly reduced fasting blood lipids: LDL cholesterol (-0.50 mmol/L; 95% confidence interval [CI]: -0.58, -0.42), high-density lipoprotein (HDL) cholesterol (-0.11 mmol/L; 95% CI: -0.14, -0.08), and total cholesterol (TC) (-0.65 mmol/L; 95% CI:-0.75, -0.55). The dietary exchange also reduced apolipoprotein (apo)B, TC:HDL cholesterol ratio, non-HDL cholesterol, E-selectin (P < 0.0001), and LDL subfraction composition (cholesterol [LDL-I and LDL-II], apoB100 [LDL-I and LDL-II], and TAG [LDL-II]) (P < 0.01). There was also an increase in plasma biomarkers of cholesterol intestinal absorption (β-sitosterol, campesterol, cholestanol), and synthesis (desmosterol) (P < 0.0001) and fold change in PBMC LDL-receptor mRNA expression relative to the higher-SFA/lower-UFA diet (P = 0.035). Marked interindividual variation in the change in serum LDL cholesterol response (-1.39 to +0.77 mmol/L) to this dietary exchange was observed, with 33.7% of this variation explained by serum LDL cholesterol before the lower-SFA/higher-UFA diet and reduction in dietary SFA intake (adjusted R2 27% and 6.7%, respectively). APOE genotype was unrelated to serum LDL cholesterol response to SFA., Conclusions: These findings support the efficacy of United Kingdom SFA dietary guidelines for the overall lowering of serum LDL cholesterol but showed marked variation in LDL cholesterol response. Further identification of the determinants of this variation will facilitate targeting and increasing the efficacy of these guidelines. The RISSCI-1 study was registered with ClinicalTrials.Gov (No. NCT03270527)., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.) more...- Published
- 2024
- Full Text
- View/download PDF
124. Long-term effects of clinical interventions on nutritional status in patients with chronic pancreatitis - A systematic review.
- Author
-
Phillips ME, Robertson MD, Hart KH, Kumar R, and Pencavel TD
- Subjects
- Dietary Supplements, Humans, Nutritional Status, Observational Studies as Topic, Retrospective Studies, Malnutrition, Pancreatitis, Chronic complications
- Abstract
Background and Aims: Malnutrition in chronic pancreatitis is complex and multifactorial, with malabsorption, pain, toxic dependencies and co-morbidities, such as diabetes, each playing a role. The aims of this systematic review were to assess the impact of nutritional intervention on markers of nutritional status in this complex patient group., Materials and Methods: A systematic review of EMBASE and PubMed was carried out in February 2020, identifying 2620 articles. After screening to exclude those reporting short term changes (less than 3 months), with only one data point, or in the wrong population, eight papers were selected for analysis., Results: Seven studies documented the impact of a nutritional intervention, one was an observational study only. Overall, studies were limited by predominantly retrospective designs, heterogenous populations and poor control of potentially confounding variables. Data could not be combined due to variability in reporting methods. All studies exploring nutritional intervention, whether that consisted of advice by a specialist dietitian, dose escalation of pancreatic enzymes, oral nutritional supplements or enteral feeding, demonstrated improved body weight and pain control, whereas patients who did not receive an intervention deteriorated nutritionally., Conclusion: Patients with chronic pancreatitis benefit from nutritional intervention. Further work is required to explore the impact of nutritional intervention on body composition and functional outcomes., Competing Interests: Declaration of competing interest MEP has received honoria for speaking from Mylan Pharmaceuticals, Nutricia Clinical Care, Merck and Sanofi. RK has received honoria for speaking from Mylan Pharmaceuticals. MDR, KHH and TDP have no conflicts of interest to declare., (Copyright © 2022 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.) more...
- Published
- 2022
- Full Text
- View/download PDF
125. Long-term changes in nutritional status and body composition in patients with malignant pancreatic disease - A systematic review.
- Author
-
Phillips ME, Robertson MD, Hart K, Kumar R, and Pencavel T
- Subjects
- Body Composition, Humans, Nutritional Status, Retrospective Studies, Malnutrition diagnosis, Malnutrition epidemiology, Pancreatic Diseases
- Abstract
Background and Aims: Patients with pancreatic cancer often experience significant deterioration in nutritional status over time. Malnutrition is complex and multifactorial, with malabsorption, pain, toxic dependencies, co-morbidities and malignant processes all playing a role. The aims of this systematic review were to assess nutritional changes over time and identify tolerance of nutritional intervention, thus identifying potential areas for further research to improve patient outcomes., Materials and Methods: A systematic review of MEDLINE, EMBASE and PubMed was carried out in February 2020, identifying 2620 articles. After screening to exclude those reporting short-term measures, with only one data point, or in the wrong population, thirteen papers were selected for analysis (four trials in neo-adjuvant treatment, five in populations undergoing palliative treatment for pancreatic cancer, and four in mixed populations undergoing pancreatic resection)., Results: Overall, studies were limited by predominantly retrospective designs, and poor control of potentially confounding variables. Meta-analysis could not be performed due to heterogenicity in study design and reporting methods. Surgery in mixed cohorts did not appear to result in weight loss. Only one small intervention study was identified. Patients with pancreatic cancer experienced a decline in nutritional status, with 44-63% of patients undergoing neoadjuvant chemotherapy having low muscle mass prior to starting treatment., Conclusion: There is a paucity of data regarding nutritional intervention in pancreatic cancer. Future work should include the use of validated functional and clinical assessment tools to further explore the impact of nutritional intervention, and the relationship between nutritional status and outcome., Competing Interests: Declaration of competing interest MEP has received honoria for speaking from Mylan Pharmaceuticals, Nutricia Clinical Care, Merck and Sanofi. RK has received honoria for speaking from Mylan Pharmaceuticals. MR, KH and TP have no conflicts of interest to declare., (Copyright © 2021 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.) more...
- Published
- 2021
- Full Text
- View/download PDF
126. Elevated high density lipoprotein cholesterol and low grade systemic inflammation is associated with increased gut permeability in normoglycemic men.
- Author
-
Robertson MD, Pedersen C, Hinton PJ, Mendis ASJR, Cani PD, and Griffin BA
- Subjects
- Adult, Aged, Biomarkers blood, C-Reactive Protein metabolism, Cross-Sectional Studies, Dyslipidemias diagnosis, Dyslipidemias physiopathology, Humans, Inflammation diagnosis, Inflammation physiopathology, Interleukin-6 blood, Lipopolysaccharides blood, Male, Middle Aged, Permeability, Up-Regulation, Cholesterol, HDL blood, Dyslipidemias blood, Inflammation blood, Inflammation Mediators blood, Intestinal Absorption, Intestines physiopathology
- Abstract
Background & Aims: Serum lipids and lipoproteins are established biomarkers of cardiovascular disease risk that could be influenced by impaired gut barrier function via effects on the absorption of dietary and biliary cholesterol. The aim of this study was to examine the potential relationship between gut barrier function (gut permeability) and concentration of serum lipids and lipoproteins, in an ancillary analysis of serum samples taken from a previous study., Methods and Results: Serum lipids, lipoproteins and functional gut permeability, as assessed by the percentage of the urinary recovery of
51 Cr-labelled EDTA absorbed within 24 h, were measured in a group of 30 healthy men. Serum lipopolysaccharide, high sensitivity C-reactive protein and interleukin-6 were also measured as markers of low-grade inflammation. The group expressed a 5-fold variation in total gut permeability (1.11-5.03%). Gut permeability was unrelated to the concentration of both serum total and low density lipoprotein (LDL)-cholesterol, but was positively associated with serum high density lipoprotein (HDL)-cholesterol (r = 0.434, P = 0.015). Serum HDL-cholesterol was also positively associated with serum endotoxaemia (r = 0.415, P = 0.023)., Conclusion: The significant association between increased gut permeability and elevated serum HDL-cholesterol is consistent with the role of HDL as an acute phase reactant, and in this situation, potentially dysfunctional lipoprotein. This finding may have negative implications for the putative role of HDL as a cardio-protective lipoprotein., (Copyright © 2018 The Italian Society of Diabetology, the Italian Society for the Study of Atherosclerosis, the Italian Society of Human Nutrition, and the Department of Clinical Medicine and Surgery, Federico II University. Published by Elsevier B.V. All rights reserved.) more...- Published
- 2018
- Full Text
- View/download PDF
127. On the role of the second-order derivative term in the calculation of convergent beam diffraction patterns.
- Author
-
Hillier SC, Robertson ET, Reid GD, Haynes RD, and Robertson MD
- Abstract
The simulation of (scanning) transmission electron microscopy images and diffraction patterns is most often performed using the forward-scattering approximation where the second-order derivative term in z is assumed to be small with respect to the first-order derivative term in the modified Schrödinger equation. This assumption is very good at high incident electron energies, but breaks down at low energies. In order to study the differences between first- and second-order methods, convergent beam electron diffraction patterns were simulated for silicon at the [111] zone-axis orientation at 20 keV and compared using electron intensity difference maps and integrated intensity profiles. The geometrical differences in the calculated diffraction patterns could be explained by an Ewald surface analysis. Furthermore, it was found that solutions based on the second-order derivative equation contained small amplitude oscillations that need to be resolved in order to ensure numerical integration stability. This required the use of very small integration steps resulting in significantly increased computation time compared to the first-order differential equation solution. Lastly, the efficiency of the numerical integration technique is discussed., (Copyright © 2017 Elsevier B.V. All rights reserved.) more...
- Published
- 2017
- Full Text
- View/download PDF
128. Reverse Monte Carlo reconstruction algorithm for discrete electron tomography based on HAADF-STEM atom counting.
- Author
-
Moyon F, Hernandez-Maldonado D, Robertson MD, Etienne A, Castro C, and Lefebvre W
- Abstract
In this paper, we propose an algorithm to obtain a three-dimensional reconstruction of a single nanoparticle based on the method of atom counting. The location of atoms in three dimensions has been successfully performed using simulations of high-angle-annular-dark-field images from only three zone-axis projections, [110], [310] and [211], for a face-centred cubic particle. These three orientations are typically accessible by low-tilt holders often used in high-performance scanning transmission electron microscopes., (© 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.) more...
- Published
- 2017
- Full Text
- View/download PDF
129. Effects of small specimen tilt and probe convergence angle on ADF-STEM image contrast of Si(0.8)Ge(0.2) epitaxial strained layers on (100) Si.
- Author
-
Wu X, Robertson MD, Kawasaki M, and Baribeau JM
- Abstract
The effects of specimen tilt and probe convergence angle on annular dark field (ADF) image contrast of Si(0.8)Ge(0.2) heteroepitaxial strained layers on (100) Si were investigated in a 200 kV scanning transmission electron microscope (STEM) for a TEM specimen thickness of 195 nm. With 0.5 degrees of specimen tilt away from the exact <011> zone-axis orientation, the signal-to-noise level of atomic columns was significantly reduced for both Si(0.8)Ge(0.2) and Si in high resolution ADF-STEM lattice images. When the specimen was tilted 0.5 degrees around the <011> axis, or the STEM probe convergence semiangle was reduced from 14.3 to 3.6 mrad, the ADF-STEM image intensity profiles across the Si(0.8)Ge(0.2) and Si layers changed significantly as compared to those obtained at the exact <011> zone axis orientation, and no longer reflected the composition changes occurring across the layer structure. Multislice image simulation results revealed that the misfit strain between the Si(0.8)Ge(0.2) and Si layers, and strain relaxation near the surface of the TEM specimen, were responsible for the observed changes in image intensity., (Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.) more...
- Published
- 2012
- Full Text
- View/download PDF
130. Impact of restraint and disinhibition on PYY plasma levels and subjective feelings of appetite.
- Author
-
Martins C, Robertson MD, and Morgan LM
- Subjects
- Adult, Cross-Over Studies, Fasting metabolism, Female, Ghrelin blood, Ghrelin metabolism, Humans, Male, Peptide YY metabolism, Postprandial Period physiology, Young Adult, Appetite physiology, Energy Intake physiology, Feeding Behavior, Peptide YY blood
- Abstract
The impact of eating behaviours on circulating levels of appetite-regulating hormones remains largely unknown. The aims of this study were to assess the role of restraint and disinhibition on fasting/postprandial peptide YY (PYY) plasma levels and subjective feelings of appetite in normal-weight individuals and to determine whether the effect was energy load dependent. 33 participants (12 men) were classified as restrained/unrestrained and low/high in disinhibition based on Three Factor Eating Questionnaire-18R and Dutch Eating Behaviour Questionnaire. The impact of restraint/disinhibition on PYY plasma levels and feelings of appetite was measured, after a 500kcal and 1000kcal breakfast, using a randomised crossover design. Restraint did not impact on either fasting or postprandial PYY plasma levels, but participants with high disinhibition had a tendency towards a blunted postprandial PYY response. Moreover, restrained eaters reported lower ratings of prospective food consumption postprandially, and a tendency towards higher fullness/lower hunger. In conclusion, circulating PYY is unaffected by restrained eating behaviour, despite being associated with increased fullness and reduced hunger in the fed state. High levels of disinhibition tend to be associated with a blunted PYY response and this may contribute towards the susceptibility to overconsumption and increased risk of weight gain characteristic of this trait. more...
- Published
- 2010
- Full Text
- View/download PDF
131. Effects of restrained eating behaviour on insulin sensitivity in normal-weight individuals.
- Author
-
Martins C, Morgan LM, and Robertson MD
- Subjects
- Adult, Analysis of Variance, Caloric Restriction, Cross-Over Studies, Fasting blood, Fatty Acids, Nonesterified blood, Feeding Behavior physiology, Female, Humans, Male, Reference Values, Triglycerides blood, Blood Glucose metabolism, Energy Intake physiology, Insulin blood, Insulin Resistance physiology, Postprandial Period physiology
- Abstract
Restrained eating behaviour has been linked to abnormalities in metabolic and endocrine functions. However, the impact of restraint on fasting insulin and glucose plasma levels and insulin sensitivity remains controversial. Moreover, the few postprandial studies to date are limited by an inappropriate sampling time frame and a low "net" energy and carbohydrate load. The aims of this study are to assess the role of dietary restraint on fasting and postprandial plasma levels of insulin, glucose, triacylglycerol (TAG) and non esterified fatty acids (NEFA) in healthy volunteers with a normal and stable body weight and to determine whether the effect of restraint on the plasma levels of the previous hormones/metabolites is load dependent. Normal-weight participants (21 women and 12 men) were classified as restrained/unrestrained based on the restraint scale of the Three Factor Eating Questionnaire-18R and Dutch Eating Behaviour Questionnaire. The impact of restraint on the plasma levels of different hormones/metabolites was measured, in response to a 500 kcal and 1000 kcal breakfast, using a randomised crossover design. Restraint was associated with lower fasting insulin plasma levels (P<0.05) and a lower insulin (P<0.015) and glucose (P<0.05) plasma levels in the postprandial state, but did not impact on TAG or NEFA. Moreover, restrained eaters showed a better fasting (P<0.05) and postprandial insulin sensitivity (P<0.01). Restrained eating behaviour has, therefore, a significant impact on both fasting and postprandial glucose metabolism, being associated with increased insulin sensitivity. These findings suggest the need for adjusting for restraint level in studies where glucose metabolism is a major outcome. more...
- Published
- 2009
- Full Text
- View/download PDF
132. A study in the computation time required for the inclusion of strain field effects in Bloch-wave simulations of TEM diffraction contrast images.
- Author
-
Dulong BJ, Haynes RD, and Robertson MD
- Abstract
As transmission electron microscopy (TEM) imaging techniques continue to become more quantitative, interpretation of the experimental images demands that accurate image simulations be computed incorporating all important aspects of the image including: compositional, crystallographic and microscope effects, as well as contrast due to strain fields arising from stresses created by lattice misfit or defects. Incorporation of the effects of strain fields in the simulation of diffraction-contrast TEM images in the Bloch-wave formalism requires the integration of a system of first-order differential equations in order to modify the excitation amplitudes and produce contrast in the image. This integration is computationally demanding with the time for integration scaling as the cube of the number of beams included in the calculation. In order to investigate the computational requirements of the integration, a variety of numerical integration packages were evaluated with respect to timing and accuracy in the simulation of quantum dot, spherical inclusion and screw dislocation images. It was determined that a class of Adams-multistep methods can provide a decrease in computation time ranging from 2 to 4 as compared to the standard Runge-Kutta 4(5) approach depending on the simulation conditions. more...
- Published
- 2008
- Full Text
- View/download PDF
133. Food perception and postprandial lipid metabolism.
- Author
-
Robertson MD
- Subjects
- Animals, Appetite physiology, Humans, Satiation physiology, Time Factors, Food, Lipid Metabolism physiology, Perception physiology, Postprandial Period
- Abstract
The postprandial response to macronutrients in the diet, particularly carbohydrates and fats, underpins the detrimental changes in metabolism (impaired glucose tolerance or postprandial hyperlipaemia) and later pathology (insulin resistance, type 2 diabetes or atherosclerosis) associated with Westernised diets. Research has shown that in addition to what and how much we eat, eating behaviour in itself may be implicated in postprandial regulation. The process of ingestion stimulates cholinergic-vagal activity, irrespective of what is eaten, important in determining both the absorption and subsequent utilisation of nutrients but also potentially food intake through effects on hunger and satiety. Modifications in this aspect of physiology have the potential to influence all aspects of postprandial metabolism and subsequent disease risk in humans. more...
- Published
- 2006
- Full Text
- View/download PDF
134. The determination of the size and shape of buried InAs/InP quantum dots by transmission electron microscopy.
- Author
-
Robertson MD, Bennett JC, Webb AM, Corbett JM, Raymond S, and Poole PJ
- Abstract
Bright-field, diffraction-contrast imaging in the transmission electron microscope has been applied to the determination of the diameter and height populations of a single layer of buried, pure, InAs/InP quantum dots (QDs). Plan-view diffraction contrast from the QDs was observed to increase significantly when the sample was tilted away from the [001] growth direction to near the [111] zone-axis orientation. This added contrast was a result of contributions to the displacement of atoms in a direction perpendicular to the electron beam arising from strain in the growth direction. Since the strain in the growth direction was about an order of magnitude larger than the strain perpendicular to the growth direction, as the sample is tilted away from the [001] zone-axis condition, the larger strain component increases the projected strain thereby increasing the QD contrast in the image. For the sample studied, both of the populations for the QD diameter and the image contrast were observed to be multimodal with the seven peaks in the contrast distribution correlating with seven distinct populations of QDs each differing in height by one monolayer (ML), from 3 to 9MLs. An analysis of the theoretically expected and experimentally observed standard deviations in the Gaussian fits to the QD diameter and height distributions provided an additional constraint in the selection of the optimal model for the multimodal distributions. more...
- Published
- 2005
- Full Text
- View/download PDF
135. Enhanced metabolic cycling in subjects after colonic resection for ulcerative colitis.
- Author
-
Robertson MD, Bickerton AS, Dennis AL, Vidal H, Jewell DP, and Frayn KN
- Subjects
- Adult, CD36 Antigens genetics, Fatty Acids, Nonesterified blood, Fatty Acids, Volatile metabolism, Female, Humans, Male, Middle Aged, PPAR gamma genetics, Sterol Esterase genetics, Triglycerides blood, Colectomy, Colitis, Ulcerative metabolism, Colitis, Ulcerative surgery, Insulin Resistance
- Abstract
Colonic resection leads to insulin resistance, but the mechanisms are unknown. We used an integrated approach to examine adipose tissue and skeletal muscle metabolism in patients lacking a colon. Ten healthy colectomized patients having undergone surgery for ulcerative colitis and 10 matched control subjects were studied with a hyperinsulinemic-euglycemic clamp to measure insulin sensitivity, an arteriovenous sampling meal tolerance study to measure postprandial substrate flux across adipose tissue and skeletal muscle, and adipose tissue and skeletal muscle biopsies to quantify the expression of genes involved in glucose and lipid metabolism. Colectomized subjects exhibited lower insulin sensitivity (homeostatic model assessment model, 33% reduction, P = 0.03; minimal model, 29% reduction, P = 0.05), elevated aldosterone (9-fold, P = 0.003), leptin (2.2-fold, P = 0.03), and an increased rate of nonesterified fatty acid and glycerol release from adipose tissue (P = 0.02) especially in the late postprandial period. The uptake of fatty acids into muscle was also significantly increased (P = 0.007), as were muscle CD36 and LPL mRNA expression compared with controls. In adipose tissue, hormone-sensitive lipase mRNA expression was increased (P = 0.015), whereas peroxisome proliferator-activated receptor-gamma expression was decreased (P = 0.02), as was that of CD36 (P = 0.001). In this study, alterations in fatty acid metabolism after colonic resection altered may have contributed to the impairment of insulin sensitivity. more...
- Published
- 2005
- Full Text
- View/download PDF
136. Plasma ghrelin response following a period of acute overfeeding in normal weight men.
- Author
-
Robertson MD, Henderson RA, Vist GE, and Rumsey RD
- Subjects
- Adult, Analysis of Variance, Fatty Acids, Nonesterified blood, Gastric Emptying physiology, Ghrelin, Humans, Leptin blood, Male, Postprandial Period, Triglycerides blood, Weight Gain physiology, Body Weight physiology, Dietary Fats administration & dosage, Eating physiology, Peptide Hormones blood
- Abstract
Background: Ghrelin, a 28 amino-acid peptide secreted primarily from the stomach has been identified as the endogenous ligand for the growth hormone secretagogue receptor. Ghrelin is suppressed in the postprandial state and has been linked to both type II diabetes and obesity., Aims: To investigate the effects of a period of overfeeding with high-fat dietary supplements on plasma ghrelin levels in nonobese men., Methods: Six healthy males (21-34 y; BMI 21-24 kg/m(2)) underwent the dietary intervention after completing diet and exercise diaries for 7 days. For 3 further weeks subjects followed their own diet diary supplemented with 125 ml single cream and 50 g roasted peanuts (88 g fat, 15 g Protein, 8 g carbohydrate) every day. Oral fat tolerance tests (OFTT) were undertaken at baseline, 7, 14 and 21 days of fat supplementation. The diet was increased in energy by 3.9 MJ/day and from a mean of 29-45% energy intake from fat with a small weight gain noted each week (P=0.009)., Results: Ghrelin concentrations were significantly reduced during the baseline OFTT. The postprandial ghrelin response (AUC) was significantly reduced following 2 weeks of dietary supplementation (P=0.005) increasing the suppression of plasma ghrelin by 18% despite only a 3% increase in body weight. Plasma triacylglycerol (P=0.009) and leptin (P=0.035) concentrations were also elevated and postprandial pancreatic polypeptide levels decreased (P=0.038) following dietary-supplementation., Conclusions: These results suggest that the metabolic profile associated with obesity, including a reduction in plasma ghrelin levels, may be related to recent dietary energy intake and precedes the development of significant adiposity. more...
- Published
- 2004
- Full Text
- View/download PDF
137. Vagal stimulation exaggerates the inhibitory ghrelin response to oral fat in humans.
- Author
-
Heath RB, Jones R, Frayn KN, and Robertson MD
- Subjects
- Adult, Analysis of Variance, Appetite Regulation, Blood Glucose analysis, Breath Tests, Dietary Fats metabolism, Female, Gastric Emptying, Ghrelin, Humans, Insulin blood, Intestinal Absorption, Male, Postprandial Period, Stimulation, Chemical, Triglycerides blood, Vagus Nerve physiology, Dietary Fats administration & dosage, Fasting, Peptide Hormones blood
- Abstract
Ghrelin, the growth hormone secretagogue receptor ligand, is a key regulator of adiposity and food intake. However, the regulation of ghrelin in response to dietary fat intake remains largely unclear. Furthermore, cephalic elevation of ghrelin may influence fat absorption and postprandial lipaemia. Therefore, the aim of this study was to examine the effect of fat ingestion and vagal stimulation on the regulation of plasma ghrelin. Vagal stimulation was achieved by modified sham feeding (MSF). Eight healthy subjects (four male/four female) consumed a 50 g fat load on two separate occasions. On one occasion, the fat load was preceded by the MSF of a meal for 1 h. Blood, appetite and breath were analysed for 5 h postprandially.A 25% (S.E.M. 3.4) suppression in ghrelin concentration was observed after fat ingestion (P<0.001), without an increase in glucose or insulin. MSF in addition to oral fat enhanced ghrelin suppression further, as well as elevating plasma triacylglycerol (P<0.001) and reducing appetite (P<0.001). The fasting ghrelin concentration was inversely correlated with gastric half-emptying time (P=0.036). We conclude that ghrelin release may be influenced directly by both vagal stimulation and oral fat ingestion. more...
- Published
- 2004
- Full Text
- View/download PDF
138. Mobilisation of enterocyte fat stores by oral glucose in humans.
- Author
-
Robertson MD, Parkes M, Warren BF, Ferguson DJ, Jackson KG, Jewell DP, and Frayn KN
- Subjects
- Adult, Biopsy, Blood Glucose metabolism, Chylomicrons blood, Dietary Carbohydrates pharmacology, Enterocytes ultrastructure, Female, Humans, Insulin blood, Intestinal Mucosa metabolism, Intestinal Mucosa ultrastructure, Jejunum ultrastructure, Male, Microscopy, Electron, Middle Aged, Postprandial Period physiology, Triglycerides blood, Dietary Fats pharmacokinetics, Enterocytes metabolism, Glucose pharmacology, Jejunum metabolism, Lipid Mobilization drug effects
- Abstract
Background and Aims: When a high fat oral load is followed several hours later by further ingestion of nutrients, there is an early postprandial peak in plasma triacylglycerol (TG). The aim of this study was to investigate the location and release of lipid from within the gastrointestinal tract., Methods: Ten healthy patients undergoing oesopho-gastro-duodenoscopy (OGD) were recruited. At t=0, all patients consumed a 50 g fat emulsion and at t=5 hours they consumed either water or a 38 g glucose solution. OGD was performed at t=6 hours and jejunal biopsy samples were evaluated for fat storage. A subgroup of five subjects then underwent a parallel metabolic study in which postprandial lipid and hormone measurements were taken during an identical two meal protocol., Results: Following oral fat at t=0, samples from patients that had subsequently ingested glucose exhibited significantly less staining for lipid within the mucosa and submucosa of the jejunum than was evident in patients that had consumed only water (p=0.028). There was also less lipid storage within the cytoplasm of enterocytes (p=0.005) following oral glucose. During the metabolic study, oral glucose consumed five hours after oral fat resulted in a postprandial peak in plasma TG, chylomicron-TG, and apolipoprotein B48 concentration compared with oral water., Conclusion: After a fat load, fat is retained within the jejunal tissue and released into plasma following glucose ingestion, resulting in a peak in chylomicron-TG which has been implicated in the pathogenesis of atherosclerosis. more...
- Published
- 2003
- Full Text
- View/download PDF
139. Prior short-term consumption of resistant starch enhances postprandial insulin sensitivity in healthy subjects.
- Author
-
Robertson MD, Currie JM, Morgan LM, Jewell DP, and Frayn KN
- Subjects
- Adult, Aged, Blood Glucose drug effects, Cross-Over Studies, Energy Intake, Female, Glucose Tolerance Test, Humans, Insulin administration & dosage, Male, Middle Aged, Postprandial Period, Reference Values, Single-Blind Method, Blood Glucose metabolism, Dietary Carbohydrates pharmacology, Insulin pharmacology, Starch pharmacology
- Abstract
Aims/hypothesis: Diets rich in insoluble-fibre are linked to a reduced risk of both diabetes and cardiovascular disease; however, the mechanism of action remains unclear. The aim of this study was to assess whether acute changes in the insoluble-fibre (resistant starch) content of the diet would have effects on postprandial carbohydrate and lipid handling., Methods: Ten healthy subjects consumed two identical, low-residue diets on separate occasions for 24 h (33% fat; <2 g dietary fibre). Of the diets one was supplemented with 60 g resistant starch (Novelose 260). On the following morning a fibre-free meal tolerance test (MTT) was carried out (59 g carbohydrate; 21 g fat; 2.1 kJ) and postprandial insulin sensitivity (SI(ORAL)) assessed using a minimal model approach., Results: Prior resistant starch consumption led to lower postprandial plasma glucose (p=0.037) and insulin (p=0.038) with a higher insulin sensitivity(44+/-7.5 vs 26+/-3.5 x 10(-4) dl kg(-1) min(-1) per micro Uml(-1); p=0.028) and C-peptide-to-insulin molar ratio (18.7+/-6.5 vs 9.7+/-0.69; p=0.017). There was no effect of resistant starch consumption on plasma triacylglycerol although non-esterified fatty acid and 3-hydroxybutyrate levels were suppressed 5 h after the meal tolerance test., Conclusion: Prior acute consumption of a high-dose of resistant starch enhanced carbohydrate handling in the postprandial period the following day potentially due to the increased rate of colonic fermentation. more...
- Published
- 2003
- Full Text
- View/download PDF
140. Second meal effect: modified sham feeding does not provoke the release of stored triacylglycerol from a previous high-fat meal.
- Author
-
Jackson KG, Robertson MD, Fielding BA, Frayn KN, and Williams CM
- Subjects
- Adult, Analysis of Variance, Area Under Curve, Chromatography, High Pressure Liquid, Dietary Fats administration & dosage, Fasting blood, Female, Humans, Male, Middle Aged, Pancreatic Polypeptide metabolism, Physical Stimulation, Postprandial Period physiology, Eating physiology, Triglycerides metabolism
- Abstract
The present study was carried out to determine whether cephalic stimulation, associated with eating a meal, was sufficient stimulus to provoke the release of stored triacylglycerol (TAG) from a previous high-fat meal. Ten subjects were studied on three separate occasions. Following a 12 h overnight fast, subjects were given a standard mixed test meal which contained 56 g fat. Blood samples were taken before the meal and for 5 h after the meal when the subjects were randomly allocated to receive either water (control) or were modified sham fed a low-fat (6 g fat) or moderate-fat (38 g fat) meal. Blood samples were collected for a further 3 h. Compared with the control, modified sham feeding a low- or moderate-fat meal did not provoke an early entry of TAG, analysed in either plasma or TAG-rich lipoprotein (TRL) fraction (density <1.006 kg/l). The TRL-retinyl ester data showed similar findings. A cephalic phase secretion of pancreatic polypeptide, without a significant increase in cholecystokinin levels, was observed on modified sham feeding. Although these data indicate that modified sham feeding was carried out successfully, analysis of the fat content of the expectorant showed that our subjects may have accidentally ingested a small amount of fat (0.7 g for the low-fat meal and 2.4 g for the moderate-fat meal). Nevertheless, an early TAG peak following modified sham feeding was not demonstrated in the present study, suggesting that significant ingestion of food, and not just oro-sensory stimulation, is necessary to provoke the release of any TAG stored from a previous meal. more...
- Published
- 2001
- Full Text
- View/download PDF
141. Prolonged effects of modified sham feeding on energy substrate mobilization.
- Author
-
Robertson MD, Jackson KG, Williams CM, Fielding BA, and Frayn KN
- Subjects
- Adult, Blood Glucose metabolism, Cholecystokinin blood, Fatty Acids, Nonesterified blood, Female, Gastrins blood, Glucagon blood, Humans, Insulin blood, Male, Middle Aged, Pancreatic Polypeptide blood, Time Factors, Triglycerides blood, Dietary Fats administration & dosage, Hormones blood, Lipid Metabolism, Postprandial Period physiology, Vagus Nerve physiology
- Abstract
Background: Vagal stimulation in response to nutrients is reported to elicit an array of digestive and endocrine responses, including an alteration in postprandial lipid metabolism., Objective: The objective of this study was to assess whether neural stimulation could alter hormone and substrate metabolism during the late postprandial phase, with implications for body fat mobilization., Design: Vagal stimulation was achieved by using the modified sham feeding (MSF) technique, in which nutrients are chewed and tasted but not swallowed. Ten healthy subjects were studied on 3 separate occasions, 4 wk apart. Five hours after a high-fat breakfast (56 g fat), the subjects were given 1 of 3 test meals allocated in random order: water, a lunch containing a modest amount of fat (38 g), or MSF (38 g fat). Blood was collected for 3 h poststimulus for hormone and metabolite analyses., Results: Plasma insulin and pancreatic polypeptide concentrations peaked at 250% and 209% of baseline concentrations within 15 min of MSF. The plasma glucose concentration increased significantly (P = 0.038) in parallel with the changes observed in the plasma insulin concentration. The nonesterified fatty acid concentration was significantly suppressed (P: = 0.006); maximum suppression occurred at a mean time of 114 min after MSF. This fall in nonesterified fatty acid was accompanied by a fall in the plasma glucagon concentration from 122 to 85 pmol/L (P = 0.018) at a mean time of 113 min after MSF., Conclusions: Effects on substrate metabolism after MSF in the postprandial state differ from those usually reported in the postabsorptive state. The effects of MSF were prolonged beyond the period of the cephalic response and these may be relevant for longer-term metabolic regulation. more...
- Published
- 2001
- Full Text
- View/download PDF
142. Evidence for altered control of glucose disposal after total colectomy.
- Author
-
Robertson MD, Livesey G, Hampton SM, and Mathers JC
- Subjects
- Adult, Aging physiology, C-Peptide blood, Colon physiology, Humans, Ileostomy, Insulin blood, Insulin Resistance physiology, Male, Middle Aged, Oxidation-Reduction, Postoperative Period, Postprandial Period physiology, Blood Glucose metabolism, Colectomy
- Abstract
Colonic fermentation of organic matter to short-chain fatty acids has been implicated in the improvement in insulin sensitivity achieved by feeding diets rich in complex carbohydrates. The present study assessed the potential role of the colon in determining postprandial glucose kinetics. Metabolic responses to a complex-carbohydrate test meal were determined in conjunction with a primed continuous infusion of D-[6,6-2H]glucose in a group of ileostomists and sex-matched controls. Glucose disposal (GD) was computed using Steele's (1959) non-steady-state kinetics on a single compartment model. Insulin sensitivity was derived using cumulative GD as the dependent variable, and time and the integrated insulin concentration as independent variables. The ileostomist group had a significantly higher postprandial plasma insulin concentration ( P = 0.034) compared with the control group, but no difference in the plasma glucose concentration. Total GD was similar in each group, although the insulin-dependent GD was substantially lower in the ileostomists (0.46 v. 0.13 mg glucose/min per pmol, P = 0.015). The ileostomist group also showed a 50% lower rate of glucose oxidation in the postprandial period (p = 0.005), although the rate of non-oxidative GD was not significantly affected. The present study indicates that loss of the colon is associated with several characteristics of the insulin resistance syndrome, and favours a view that the colon has a role in the control of postprandial glucose. more...
- Published
- 2000
143. Gastric emptying rate of solids is reduced in a group of ileostomy patients.
- Author
-
Robertson MD and Mathers JC
- Subjects
- Adult, Case-Control Studies, Colitis, Ulcerative metabolism, Colitis, Ulcerative surgery, Dietary Carbohydrates metabolism, Dietary Fats metabolism, Female, Humans, Male, Middle Aged, Postoperative Period, Reference Values, Gastric Emptying, Ileostomy
- Abstract
Feedback inhibition from the colon acts as a potent inhibitor of gastrointestinal motility via an array of gut peptides and neural pathways. The effect of total colonectomy on gastric emptying was assessed in five healthy ileostomy patients (<5 cm ileal resection) and five matched controls. Each subject consumed two isoenergetic test meals of contrasting fat-carbohydrate ratio in random order. Emptying of solids was measured using the [13C]octanoic acid breath test, and liquid emptying was assessed after oral dosing with paracetamol. Ileostomist subjects exhibited an increased half-emptying time for solids (P = 0.047), which included components of an increased gastric lag time (P = 0.004) and a reduction in the linear emptying rate (P = 0.003). There was no difference in the pattern of liquid emptying between subject groups. In conclusion, the gastric emptying rate of solids was reduced in ileostomy patients compared with controls. more...
- Published
- 2000
- Full Text
- View/download PDF
144. Olanzapine concentrations in clinical serum and postmortem blood specimens--when does therapeutic become toxic?
- Author
-
Robertson MD and McMullin MM
- Subjects
- Antipsychotic Agents blood, Antipsychotic Agents pharmacology, Autopsy, Benzodiazepines, Blood Chemical Analysis, Dose-Response Relationship, Drug, Forensic Medicine, Humans, Olanzapine, Pirenzepine blood, Pirenzepine pharmacology, Pirenzepine poisoning, Antipsychotic Agents poisoning, Pirenzepine analogs & derivatives
- Abstract
The concentration of olanzapine (Zyprexa) was determined in 1653 clinical serum specimens during routine drug monitoring, and in 58 postmortem whole blood specimens as part of routine toxicological analysis. The analysis of olanzapine was performed by the solid-phase extraction of 1.0 mL of buffered serum or blood, followed by gas chromatography separation with nitrogen-phosphorus detection. The analysis of the clinical serum samples showed that 86% of positive serum values were within the range of 5 to 75 ng/mL, with a mean and median of 36 and 26 ng/mL, respectively. These data suggest that the concentrations of olanzapine expected during therapy may be higher than those previously reported. In 58 postmortem whole blood specimens the mean olanzapine concentration was 358 ng/mL with a range of 10 to 5200 ng/mL. Further, investigation of deaths involving olanzapine suggest that potential toxicity should be considered at concentrations above 100 ng/mL. Although the majority of the olanzapine-related deaths were associated with many other drugs, death primarily due to olanzapine toxicity was determined at concentrations in post-mortem blood as low as 160 ng/mL. more...
- Published
- 2000
145. Stability of nitrobenzodiazepines in postmortem blood.
- Author
-
Robertson MD and Drummer OH
- Subjects
- Benzodiazepines analysis, Blood Preservation methods, Blood Preservation standards, Cadaver, Clonazepam analysis, Clonazepam blood, Drug Stability, Forensic Medicine methods, GABA Modulators analysis, GABA Modulators blood, Humans, Hypnotics and Sedatives analysis, Hypnotics and Sedatives blood, Nitrazepam analysis, Nitrazepam blood, Nitro Compounds analysis, Sodium Fluoride, Temperature, Time Factors, Toxicology methods, Water analysis, Benzodiazepines blood, Nitro Compounds blood, Postmortem Changes
- Abstract
Studies were undertaken to determine the stability of nitrobenzodiazepines and their 7-amino metabolites in water and blood. At 22 degrees C nitrazepam and clonazepam were stable in sterile fresh blood containing preservative over 28 days, whereas 25% of flunitrazepam was degraded. At 37 degrees C all three drugs were substantially lost over 9 h (29-51%). There was only a small loss observed for the 7-amino metabolites and no substantial amounts of parent drug and 7-amino metabolite were degraded in water under these conditions. In the absence of preservative substantial amounts (25-50%) of parent drugs were lost in fresh blood over 10 days at 22 degrees C. In bacterially-contaminated postmortem blood all three drugs were completely degraded over 8 h at 22 degrees C with almost all drug completely converted to the respective 7-amino metabolite. These metabolites were also partially degraded (10-20%) over 45 h at 22 degrees C. All 3 nitrobenzodiazepines were stable in blood stored for up to 24 months at -20 degrees C, or 4 degrees C over 10 months. Their respective 7-amino metabolites were, however, relatively unstable at -20 degrees C with a significant loss (29%) after 2 months. At 4 degrees C a 21% loss occurred after 1 month. Freeze/thawing was found not to affect the concentration of nitrobenzodiazepine and 7-amino metabolites. These results show that the nitrobenzodiazepines and their metabolites are unstable chemically and metabolically in blood. We advise that blood collected for the purpose of nitrobenzodiazepine determinations should be preserved with sodium fluoride, stored at -20 degrees C and assayed as soon as practicable, preferably within a week of collection. more...
- Published
- 1998
146. Postmortem distribution and redistribution of nitrobenzodiazepines in man.
- Author
-
Robertson MD and Drummer OH
- Subjects
- Autopsy, Bile chemistry, Chromatography, High Pressure Liquid, Clonazepam blood, Clonazepam urine, Flunitrazepam blood, Flunitrazepam urine, GABA Modulators blood, GABA Modulators urine, Humans, Hypnotics and Sedatives blood, Hypnotics and Sedatives urine, Liver chemistry, Nitrazepam blood, Nitrazepam urine, Time Factors, Tissue Distribution, Vitreous Body chemistry, Clonazepam analysis, Flunitrazepam analysis, GABA Modulators analysis, Hypnotics and Sedatives analysis, Nitrazepam analysis, Postmortem Changes
- Abstract
The distribution of the nitrobenzodiazepines, flunitrazepam, clonazepam and nitrazepam, and their respective 7-amino metabolites were examined in blood, serum, vitreous humor, liver, bile and urine of decedents taking these drugs. Peripheral blood, serum and liver concentrations were not significantly different to each other. However, vitreous concentrations were one-third of blood, while bile concentrations were 5-12 fold higher. Blood, serum and vitreous contained predominantly the 7-amino metabolite, liver contained only the metabolite, while bile contained significant concentrations of both the parent drug and the 7-amino metabolite. Urine contained only small concentrations of parent drug, however, as expected a number of metabolites were detected. Redistribution studies compared the drug concentrations of femoral blood, taken at body admission to the mortuary, with femoral blood taken at autopsy approximately 39 h later in 48 cases. The concentrations of 7-amino metabolites were not significantly different, however the concentrations of parent nitrobenzodiazepines were significantly higher in the admission specimens. In 6 cases in which subclavian blood was taken, the concentrations were not significantly different to the concentrations in admission blood. Similar findings were observed when femoral and subclavian blood concentrations were compared in 6 cases. There was also no apparent difference in total blood concentrations of nitrobenzodiazepines when blood concentrations taken in hospital shortly prior to death were compared to postmortem blood. Postmortem diffusion into peripheral blood is therefore not a confounding factor in the interpretation of nitrobenzodiazepine concentrations. more...
- Published
- 1998
147. Sociopathy: forever forensic?
- Author
-
Robertson MD, Bray A, and Parker GB
- Subjects
- Antisocial Personality Disorder history, Diagnosis, Differential, Europe, History, 20th Century, History, Ancient, Humans, Roman World, Antisocial Personality Disorder diagnosis, Antisocial Personality Disorder psychology
- Abstract
We suggest that the criteria for antisocial personality disorder, or "sociopathy", in the Diagnostic and statistical manual of mental disorders (4th edition) are deficient in that they define "failed sociopathy", and fail to include an equally valid group of individuals who, although seen by society as successful, display core features of the antisocial personality disorder. more...
- Published
- 1996
- Full Text
- View/download PDF
148. Postmortem drug metabolism by bacteria.
- Author
-
Robertson MD and Drummer OH
- Subjects
- Adult, Bacillus cereus metabolism, Bacteria drug effects, Bacteroides fragilis metabolism, Clostridium perfringens metabolism, Humans, Hydrogen-Ion Concentration, Male, Middle Aged, Sodium Fluoride pharmacology, Species Specificity, Staphylococcus aureus metabolism, Staphylococcus epidermidis metabolism, Temperature, Time Factors, Bacteria metabolism, Benzodiazepines metabolism, Postmortem Changes
- Abstract
Studies were undertaken to determine the possible role of enteric bacteria in the postmortem bioconversion of the nitrobenzodiazepines flunitrazepam, clonazepam, and nitrazepam. Flunitrazepam, clonazepam, and nitrazepam were completely metabolized in blood in the presence of eight species of enteric bacteria to their respective 7-amino-metabolites. The rates of metabolism, at 37 degrees C, ranged from 0.1 ng/mL/min for Streptococcus faecalis to 8.8 ng/mL/min for Clostridium perfringens. The rate of conversion was reduced to 87% by a combination of 0.7% (w/v) sodium fluoride and potassium oxalate, and almost completely inhibited (96%) by 1% (w/v) sodium fluoride. pH had variable effects on the rate of metabolic bioconversion of nitrobenzodiazepines, while increasing temperatures were found to generally increase the rate of nitrobenzodiazepine bioconversion. These data support the proposal that bacteria may mediate postmortem bioconversion of the nitrobenzodiazepines. more...
- Published
- 1995
149. Contrasting bronchoalveolar leukocyte responses in rats inhaling coal mine dust, quartz, or titanium dioxide: effects of coal rank, airborne mass concentration, and cessation of exposure.
- Author
-
Donaldson K, Brown GM, Brown DM, Robertson MD, Slight J, Cowie H, Jones AD, Bolton RE, and Davis JM
- Subjects
- Administration, Inhalation, Animals, Atmosphere Exposure Chambers, Bronchi immunology, Bronchoalveolar Lavage Fluid analysis, Kinetics, L-Lactate Dehydrogenase analysis, Male, Rats, Air Pollutants, Occupational adverse effects, Bronchi drug effects, Coal, Dust adverse effects, Leukocytes drug effects, Quartz, Silicon Dioxide, Titanium
- Abstract
The aim of this study was to determine the bronchoalveolar leukocyte response to airborne coal mine dust; quartz and titanium dioxide were used as positive and negative controls, respectively. Groups of rats were exposed to airborne mass concentrations of 10 and 50 mg/m3 of the dusts for 7 hr/day, 5 days/week and their bronchoalveolar space was lavaged at time points between 2 and 75 days of exposure, to assess the leukocyte response. This study revealed time-dependent and airborne mass concentration-dependent recruitment of neutrophils and macrophages into the bronchoalveolar region with coal mine dust inhalation but no real difference in the magnitude of the response between coal mine dusts from collieries mining coal of different rank and quartz content although the maximum quartz content in the dusts used was 6%. The inflammatory response was much less than that produced by quartz, at similar airborne mass concentrations, and more than that produced by titanium dioxide which was, in general, a poor inflammogen in the rat lung. Groups of rats were exposed to the airborne dusts for 32 or 75 days, then removed from the exposure chambers, and allowed to recover by breathing room air for a further 64 days. During this recovery period there was marked progression of the leukocyte response with quartz and persistence of the response with coal mine dust. Chronic recruitment of leukocytes to the lungs of individuals inhaling coal mine dust is likely to be an important factor in the development of coal workers' pneumoconiosis. more...
- Published
- 1990
- Full Text
- View/download PDF
150. Phagocytic cell responses to Aspergillus fumigatus.
- Author
-
Robertson MD, Seaton A, and Raeburn JA
- Subjects
- Animals, Aspergillosis etiology, Humans, In Vitro Techniques, Lung Diseases, Fungal etiology, Mice, Phagocytosis, Spores, Fungal immunology, Aspergillus fumigatus immunology, Phagocytes immunology
- Published
- 1989
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.