168 results on '"Hamilton CJ"'
Search Results
2. Nitrates and bone turnover (NABT) - trial to select the best nitrate preparation: study protocol for a randomized controlled trial.
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Cummings, Steven, Bucur, RC, Reid, LS, Hamilton, CJ, Cummings, SR, and Jamal, SA
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Organic nitrates uncouple bone turnover, improve bone mineral density, and improve trabecular and cortical components of bone. These changes in turnover, strength and geometry may translate into an important reduction in fractures. However, before proceedi
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- 2013
3. Steam Fluidised Bed Drying of Coal
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International Coal Engineering Conference (1990 : Sydney, N.S.W.) and Hamilton, CJ
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- 1990
4. Moves, Mergers & Mayhem: Recent Library Developments In CAB International
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Hamilton, CJ
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- 1991
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5. Commentary on “Recruiting and training foster carers for teenagers “at risk” of or experiencing child sexual exploitation”
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Hamilton, Cj, primary
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- 2019
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6. LARGE-SCALE PRODUCTION OF HYDROGEN BY NUCLEAR ENERGY FOR THE HYDROGEN ECONOMY
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SCHULTZ, KR, primary, BROWN, LC, additional, BESENBRUCH, GE, additional, and HAMILTON, CJ, additional
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- 2003
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7. Commercialization of the Lurgi LR Oil Shale Process
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Chemeca 88 (16th : 1988 : Sydney, N.S.W.), Weiss, HJ, and Hamilton, CJ
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- 1988
8. Identification of candidate genes in ulcerative colitis and Crohn's disease using cDNA array technology
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Hamilton Cj, McAuliffe Tl, Grimes Hl, Sonja M. S. Uthoff, Fox Mp, Susan Galandiuk, Maurice R Eichenberger, and Robert K. Lewis
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Cancer Research ,Candidate gene ,Frizzled ,Biology ,medicine.disease_cause ,Inflammatory bowel disease ,Crohn Disease ,Intestinal mucosa ,medicine ,Humans ,Gene ,DNA Primers ,Oligonucleotide Array Sequence Analysis ,Inflammation ,Crohn's disease ,Reverse Transcriptase Polymerase Chain Reaction ,Gene Expression Profiling ,Wnt signaling pathway ,Membrane Proteins ,DNA, Neoplasm ,medicine.disease ,Oncology ,Immunology ,Cancer research ,Colitis, Ulcerative ,Carcinogenesis - Abstract
Inflammatory bowel disease (IBD) follows a multigenic mode of inheritance, encompassing the clinically discrete phenotypes of ulcerative colitis (UC) and Crohn's disease (CD). The risk of malignant transformation of the colon increases with the duration and extent of IBD and is particularly high for patients with a longstanding history of UC. We wished to identify candidate genes that might be involved in disease pathogenesis based on functional plausibility and their putative role in IBD carcinogenesis. Polyadenylated mRNA (PolyA+ mRNA) preparation from inflamed intestinal mucosa of patients with a longstanding history of UC and CD was performed with subsequent hybridization of alpha phosphorus [alpha-32P]-deoxyadenotriphosphate-labeled complementary deoxyribonucleic acid (DNA) populations to nucleic acid arrays. Of 588 different human gene transcripts arrayed, secreted apoptosis-related protein 1 (Sarp1), frizzled (fz) homologues, and disheveled (dvl) were differentially expressed, being elevated in UC as compared to CD. These genes encode proteins involved in the Wingless-type (Wnt)/beta-catenin signaling pathway. The autonomous expression of Sarp1 and Sarp1-compatible fz receptor genes suggests that the Wnt pathway may be involved in UC carcinogenesis.
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- 2001
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9. Placental histopathology after Coxiella burnetii infection during pregnancy.
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Munster JM, Leenders AC, Hamilton CJ, Hak E, Aarnoudse JG, and Timmer A
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- 2012
10. Topical nitrates for osteoporosis: A cheap future direction?
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Jamal SA and Hamilton CJ
- Published
- 2011
11. LARGE-SCALE PRODUCTION OF HYDROGEN BY NUCLEAR ENERGY FOR THE HYDROGEN ECONOMY
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HAMILTON, CJ
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- 2003
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12. Memory strategies in autistic and older adults.
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Torenvliet C, Groenman AP, Van der Burg E, Charlton RC, Hamilton CJ, and Geurts HM
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- Humans, Male, Female, Adult, Middle Aged, Young Adult, Aged, Memory physiology, Aging psychology, Aging physiology, Adolescent, Neuropsychological Tests statistics & numerical data, Age Factors, Autistic Disorder psychology
- Abstract
Memory strategies in autistic adults seem to mimic strategies at older age, as both younger autistic and older non-autistic individuals use fewer semantic features in visual memory tasks. Therefore, the current study aims to investigate whether early differences in memory strategies lead to altered age-related effects in autism, particularly whether initial difficulties in strategy use become advantageous at older age (i.e., "protective aging"). A total of 147 participants across four groups (autistic younger/older, non-autistic younger/older) completed an online assessment. This assessment included a recognition version of the Visual Patterns Test (VPT) to evaluate semantic strategy use in visual memory, the Just Noticeable Difference (JND) size task for assessing visual processing, and the Multifactorial Memory Questionnaire to evaluate subjective memory functioning and strategy use (MMQ). Unexpectedly, all groups benefited from semantic features on the VPT, although the older groups performed less accurately and slower than the younger groups. The JND Size task showed no group differences. Autistic adults rated their MMQ memory as worse than non-autistic adults, despite reporting greater strategy use. These results indicate that cognitive strategies might be more similar between younger/older and autistic/non-autistic people than previously expected, although notable discrepancies between objective and subjective measures were present. They also substantiate previously reported parallel (i.e., similar) age-related effects between autistic and non-autistic people., (© 2024 The Author(s). Autism Research published by International Society for Autism Research and Wiley Periodicals LLC.)
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- 2024
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13. [Formula: see text] Beyond the rubicon: a continuum approach to investigating the impact of ADHD like characteristics on everyday executive function in children with Tourette Syndrome.
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Hamilton CJ and Harrison K
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- Child, Humans, Executive Function, Cognition, Parents, Attention Deficit Disorder with Hyperactivity psychology, Tourette Syndrome complications
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Across a range of neurodevelopmental conditions, a diagnosis of attention deficit hyperactivity disorder (ADHD) has been shown to be associated with executive function impairment. However, the DSM-V emphasis upon viewing psychological characteristics as existing on a continuous distributed quantitative dimension has enabled the opportunity to consider the influence of sub-diagnostic or sub-referral levels of these psychological characteristics upon cognitive function. This study adopted a continuum approach to the consideration of this ADHD influence and examined the extent to which the difference in parental reported executive functions between children with Tourette syndrome (TS) or typically developing children could be mediated by a concurrent group difference in the possession of sub-referral levels of ADHD-like characteristics. A total of 146 children, 58 with reported TS diagnosis, participated. Parental report measures of ecological executive functioning, the Child Executive Functioning Inventory, and the Vanderbilt ADHD Diagnostic Parent Rating Scale were employed. The analyses with a full sample and a sub-referral sample revealed significant group differences in most of the key measures. In addition, these measures were highly correlated even when controlling for age and gender. A series of mediation analyses indicated that in all models, the ADHD-like measures significantly mediated the group difference in executive function. These results suggest that sub-referrals levels of ADHD-like characteristics continue to contribute to executive challenges in TS. Future intervention research targeting these executive functions should consider the presence of ADHD-like characteristics at sub-referral levels of possession.
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- 2024
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14. Heated Behaviour in the Classroom for Children with FASD: The Relationship between Characteristics Associated with ADHD, ODD and ASD, Hot Executive Function and Classroom Based Reward Systems.
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Carrick A and Hamilton CJ
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Possession of characteristics related to Attention Deficit Hyperactive Disorder, Oppositional Defiance Disorder, and Autism Spectrum Disorder in children prenatally exposed to alcohol contributes to challenges within the diagnostic pathway for Foetal Alcohol Spectrum Disorder (FASD). The presentation of these characteristics, though problematic for the children affected, may not result in referral for diagnosis; focusing on diagnostic thresholds masks the dimensional nature of these characteristics. Children with traits which are undiagnosed may not receive effective support and are often identified as exhibiting challenging behaviour. In the UK, children with undiagnosed Special Educational Needs (SEN) are more likely to experience school exclusion. Common across each condition are challenges to executive function associated with emotional regulation (hot-executive function). This study explored the relationship between characteristics of Attention Deficit Hyperactive Disorder, Oppositional Defiance Disorder, Autistic-Like Traits, and hot executive functions on the helpfulness of reward-based interventions for children with suspected or diagnosed FASD. Data were collected online using caregiver referral questionnaire screeners for each measure (Child Autism Quotient Questionnaire, Vanderbilt ADHD Parental Rating Scale and The Childhood Executive Functioning Inventory) for children aged 6-12 years with suspected or diagnosed FASD ( n = 121). Between-group comparisons showed no significant difference in the reporting of Attention Deficit Hyperactive Disorder characteristics, Oppositional Defiance Disorder characteristics, Autistic-Like Traits, and executive function, regardless of diagnostic state. Multiple regression analyses indicated that these personality characteristics and executive functions were associated with the perception of the reward system helpfulness. However, this pattern was qualified by both the type of hot executive function challenged (significant for Regulation not Inhibition) and whether the child had an FASD diagnosis. Thus, a dimensional approach may strengthen our understanding of the child's classroom experience and help overcome barriers to effective intervention and support.
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- 2023
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15. Development and implementation of a pharmacist-led telehealth medication management program for veterans receiving oral antineoplastic therapies through the MISSION Act.
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Passey D, Healy R, Qualls J, Hamilton CJ, Tilley E, Burningham Z, Sauer B, and Halwani A
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- Humans, Medication Therapy Management, Patient Satisfaction, Pharmacists, Antineoplastic Agents, Telemedicine, Veterans
- Abstract
Purpose: Veterans prescribed oral antineoplastic therapies (OATs) by community providers outside the Veterans Health Administration (VA) may lack access to comprehensive medication management. To address this, our multidisciplinary team developed and implemented a pharmacist-led telehealth medication management program for veterans prescribed OATs by community providers., Summary: The program exclusively uses telehealth to connect veterans with a dedicated board-certified clinical oncology pharmacist who provides comprehensive medication management. The program is based on established pharmacy models found in the research literature. We developed a standard operating procedure, communication templates, patient education materials, and a suite of health information technology tools to help streamline pharmacy processes. The Consolidated Framework for Implementation Research was used to design implementation strategies to promote the adoption of the program. In the first year, 64 veterans from 3 VA medical centers were enrolled in the program. The oncology clinical pharmacist performed 342 encounters and 101 interventions. The program saved an estimated $200,724 in medication-related costs. The veterans we surveyed reported high levels of satisfaction with the pharmacy services provided by the program., Conclusion: The delivery of comprehensive medication management through telehealth is feasible from a healthcare system perspective and beneficial for patients. The board-certified oncology clinical pharmacist provided remote pharmacy services to Veterans across three sites in a large and rural service area for the VA. The program realized several benefits, including positive clinical outcomes, high levels of patient satisfaction, and cost savings on medication-related costs., (© American Society of Health-System Pharmacists 2022. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)
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- 2022
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16. Renal Protective Effect of Everolimus in Liver Transplantation: A Prospective Randomized Open-Label Trial.
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Kadry Z, Stine JG, Dohi T, Jain A, Robyak KL, Kwon O, Hamilton CJ, Janicki P, Riley TR 3rd, Butt F, Krok K, Schreibman IR, Bezinover D, Ghahramani N, Campos S, and Hollenbeak CS
- Abstract
Renal dysfunction is associated with poor long-term outcomes after liver transplantation. We examined the renal sparing effect of everolimus (EVR) compared to standard calcineurin inhibitor (CNI) immunosuppression with direct measurements of renal function over 24 months., Methods: This was a prospective, randomized, open-label trial comparing EVR and mycophenolic acid (MPA) with CNI and MPA immunosuppression. An Investigational New Drug Application (IND # 113882) was obtained with the Food and Drug Administration as EVR is only approved for use with low-dose tacrolimus. Serum creatinine, 24-hour urine creatinine clearance, iothalamate clearance, Cockcroft-Gault creatinine clearance (CrCl), and Modification of Diet in Renal Disease estimated glomerular filtration rate were prospectively measured at 4 study visits. Nonparametric statistical tests were used for analyses, including the Mann-Whitney U test for continuous outcomes and Pearson's chi-square test for binary outcomes. Effect size was measured using Cohen's d . Patients also completed quality of life surveys using the FACT-Hep instrument at each study visit. Comparison between the 2 groups was performed using the Student t test., Results: Each arm had 12 subjects; 4 patients dropped out in the EVR arm and 1 in the CNI arm by 24 months. Serum creatinine ( P = 0.015), Modification of Diet in Renal Disease estimated glomerular filtration rate ( P = 0.013), and 24-hour urine CrCL ( P = 0.032) were significantly better at 24 months with EVR. Iothalamate clearance showed significant improvement at 12 months ( P = 0.049) and a trend toward better renal function ( P = 0.099) at 24 months. There was no statistical significance with Cockcroft-Gault CrCl. Adverse events were not significantly different between the 2 arms. The EVR group also showed significantly better physical, functional, and overall self-reported quality of life ( P = 0.01) at 24 months., Conclusions: EVR with MPA resulted in significant long-term improvement in renal function and quality of life at 24 months after liver transplantation compared with standard CNI with MPA immunosuppression., Competing Interests: The authors declare no conflicts of interest., (Copyright © 2021 The Author(s). Transplantation Direct. Published by Wolters Kluwer Health, Inc.)
- Published
- 2021
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17. The Disulfide Stress Response and Protein S -thioallylation Caused by Allicin and Diallyl Polysulfanes in Bacillus subtilis as Revealed by Transcriptomics and Proteomics.
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Chi BK, Huyen NTT, Loi VV, Gruhlke MCH, Schaffer M, Mäder U, Maaß S, Becher D, Bernhardt J, Arbach M, Hamilton CJ, Slusarenko AJ, and Antelmann H
- Abstract
Garlic plants ( Allium sativum L.) produce antimicrobial compounds, such as diallyl thiosulfinate (allicin) and diallyl polysulfanes. Here, we investigated the transcriptome and protein S -thioallylomes under allicin and diallyl tetrasulfane (DAS4) exposure in the Gram-positive bacterium Bacillus subtilis . Allicin and DAS4 caused a similar thiol-specific oxidative stress response, protein and DNA damage as revealed by the induction of the OhrR, PerR, Spx, YodB, CatR, HypR, AdhR, HxlR, LexA, CymR, CtsR, and HrcA regulons in the transcriptome. At the proteome level, we identified, in total, 108 S -thioallylated proteins under allicin and/or DAS4 stress. The S -thioallylome includes enzymes involved in the biosynthesis of surfactin (SrfAA, SrfAB), amino acids (SerA, MetE, YxjG, YitJ, CysJ, GlnA, YwaA), nucleotides (PurB, PurC, PyrAB, GuaB), translation factors (EF-Tu, EF-Ts, EF-G), antioxidant enzymes (AhpC, MsrB), as well as redox-sensitive MarR/OhrR and DUF24-family regulators (OhrR, HypR, YodB, CatR). Growth phenotype analysis revealed that the low molecular weight thiol bacillithiol, as well as the OhrR, Spx, and HypR regulons, confer protection against allicin and DAS4 stress. Altogether, we show here that allicin and DAS4 cause a strong oxidative, disulfide and sulfur stress response in the transcriptome and widespread S -thioallylation of redox-sensitive proteins in B. subtilis . The results further reveal that allicin and polysulfanes have similar modes of actions and thiol-reactivities and modify a similar set of redox-sensitive proteins by S -thioallylation., Competing Interests: The authors declare no conflict of interest.
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- 2019
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18. The Health Professionals' Services Program: Oregon's Alternative-to-Discipline Monitoring Program for Nurses.
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Hamilton CJ
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- Humans, Oregon, Licensure legislation & jurisprudence, Mental Disorders, Nurses legislation & jurisprudence, Professional Impairment legislation & jurisprudence, Substance-Related Disorders
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- 2019
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19. Staphylococcus aureus Uses the Bacilliredoxin (BrxAB)/Bacillithiol Disulfide Reductase (YpdA) Redox Pathway to Defend Against Oxidative Stress Under Infections.
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Linzner N, Loi VV, Fritsch VN, Tung QN, Stenzel S, Wirtz M, Hell R, Hamilton CJ, Tedin K, Fulde M, and Antelmann H
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Staphylococcus aureus is a major human pathogen and has to cope with reactive oxygen and chlorine species (ROS, RCS) during infections. The low molecular weight thiol bacillithiol (BSH) is an important defense mechanism of S. aureus for detoxification of ROS and HOCl stress to maintain the reduced state of the cytoplasm. Under HOCl stress, BSH forms mixed disulfides with proteins, termed as S -bacillithiolations, which are reduced by bacilliredoxins (BrxA and BrxB). The NADPH-dependent flavin disulfide reductase YpdA is phylogenetically associated with the BSH synthesis and BrxA/B enzymes and was recently suggested to function as BSSB reductase (Mikheyeva et al., 2019). Here, we investigated the role of the complete bacilliredoxin BrxAB/BSH/YpdA pathway in S. aureus COL under oxidative stress and macrophage infection conditions in vivo and in biochemical assays in vitro . Using HPLC thiol metabolomics, a strongly enhanced BSSB level and a decreased BSH/BSSB ratio were measured in the S. aureus COL Δ ypdA deletion mutant under control and NaOCl stress. Monitoring the oxidation degree (OxD) of the Brx-roGFP2 biosensor revealed that YpdA is required for regeneration of the reduced BSH redox potential ( E
BSH ) upon recovery from oxidative stress. In addition, the Δ ypdA mutant was impaired in H2 O2 detoxification as measured with the novel H2 O2 -specific Tpx-roGFP2 biosensor. Phenotype analyses further showed that BrxA and YpdA are required for survival under NaOCl and H2 O2 stress in vitro and inside murine J-774A.1 macrophages in infection assays in vivo . Finally, NADPH-coupled electron transfer assays provide evidence for the function of YpdA in BSSB reduction, which depends on the conserved Cys14 residue. YpdA acts together with BrxA and BSH in de-bacillithiolation of S -bacillithiolated GapDH. In conclusion, our results point to a major role of the BrxA/BSH/YpdA pathway in BSH redox homeostasis in S. aureus during recovery from oxidative stress and under infections.- Published
- 2019
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20. Antimicrobial garlic-derived diallyl polysulfanes: Interactions with biological thiols in Bacillus subtilis.
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Arbach M, Santana TM, Moxham H, Tinson R, Anwar A, Groom M, and Hamilton CJ
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- Anti-Bacterial Agents chemistry, Cysteine metabolism, Glucosamine metabolism, Anti-Bacterial Agents pharmacology, Bacillus subtilis metabolism, Cysteine analogs & derivatives, Garlic chemistry, Glucosamine analogs & derivatives
- Abstract
Background: Diallylpolysulfanes are the key constituents of garlic oils, known to exhibit broad spectrum anticancer and antimicrobial activity. Studies in vitro, and in mammalian cells, have shown they react, via thiol-polysulfane exchange, with their major low molecular weight thiol, glutathione. However, there are no detailed reports of diallylpolysulfane effects on other common thiol metabolites (cysteine and coenzyme A) or major thiol cofactors (e.g. bacillithiol) that many Gram positive bacteria produce instead of glutathione., Methods: Diallylpolysulfanes were individually purified then screened for antimicrobial activity against Bacillus subtilis. Their impact on thiol metabolites (bacillithiol, cysteine, coenzyme A, protein thiols allyl thiols//persulfides) in B. subtilis cultures were analysed, by HPLC., Results: Diallylpolysulfane bioactivity increased with increasing chain length up to diallyltetrasulfane, but then plateaued. Within two minutes of treating B. subtilis with diallyltrisulfane or diallyltetrasulfane intracellular bacillithiol levels decreased by ~90%. Cysteine and CoA were also affected but to a lesser degree. This was accompanied by the accumulation of allyl thiol and allyl persulfide. A significant level of protein-S-allylation was also detected., Conclusions: In addition to the major low molecular weight thiol, diallylpolysulfanes can also have an impact on other thiol metabolites and protein thiols., General Significance: This study shows the rapid parallel impact of polysulfanes on different biological thiols inside Bacillus subtilis alongside the concomitant generation of allyl thiols and persulfides., (Copyright © 2019 Elsevier B.V. All rights reserved.)
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- 2019
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21. Mass spectrometric studies of Cu(I)-binding to the N-terminal domains of B. subtilis CopA and influence of bacillithiol.
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Kay KL, Hamilton CJ, and Le Brun NE
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- Cysteine metabolism, Dimerization, Glucosamine metabolism, Protein Binding, Bacillus subtilis metabolism, Bacterial Proteins metabolism, Copper metabolism, Cysteine analogs & derivatives, Glucosamine analogs & derivatives, Spectrometry, Mass, Electrospray Ionization methods
- Abstract
CopA is a Cu(I)-exporting transmembrane P
1B -type ATPase from Bacillus subtilis. It contains two N-terminal cytoplasmic domains, CopAab, which bind Cu(I) with high affinity and to form higher-order complexes with multiple Cu(I) ions. To determine the precise nature of these species, electrospray ionisation mass spectrometry (ESI-MS) under non-denaturing conditions was employed. Up to 1 Cu per CopAab resulted in Cu coordination to one or both CopAab domains. At >1 Cu/CopAab, two distinct dimeric charge state envelopes were observed, corresponding to distinct conformations, each with Cu6 (CopAab)2 as its major form. The influence of the physiologically relevant low molecular weight thiol bacillithiol (BSH) on Cu(I)-binding to CopAab was assessed. Dimeric CopAab persisted in the presence of BSH, with previously undetected Cu7 (CopAab)2 and Cu6 (CopAab)2 (BSH) forms apparent., (Copyright © 2018 Elsevier Inc. All rights reserved.)- Published
- 2019
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22. Physiological Studies of Chlorobiaceae Suggest that Bacillithiol Derivatives Are the Most Widespread Thiols in Bacteria.
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Hiras J, Sharma SV, Raman V, Tinson RAJ, Arbach M, Rodrigues DF, Norambuena J, Hamilton CJ, and Hanson TE
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- Cysteine chemistry, Cysteine metabolism, Genome, Bacterial, Glucosamine chemistry, Glucosamine metabolism, Molecular Structure, Molecular Weight, Biosynthetic Pathways genetics, Chlorobi genetics, Chlorobi metabolism, Cysteine analogs & derivatives, Glucosamine analogs & derivatives
- Abstract
Low-molecular-weight (LMW) thiols mediate redox homeostasis and the detoxification of chemical stressors. Despite their essential functions, the distribution of LMW thiols across cellular life has not yet been defined. LMW thiols are also thought to play a central role in sulfur oxidation pathways in phototrophic bacteria, including the Chlorobiaceae Here we show that Chlorobaculum tepidum synthesizes a novel LMW thiol with a mass of 412 ± 1 Da corresponding to a molecular formula of C
14 H24 N2 O10 S, which suggests that the new LMW thiol is closely related to bacillithiol (BSH), the major LMW thiol of low-G+C Gram-positive bacteria. The Cba. tepidum LMW thiol structure was N-methyl-bacillithiol (N-Me-BSH), methylated on the cysteine nitrogen, the fourth instance of this modification in metabolism. Orthologs of bacillithiol biosynthetic genes in the Cba. tepidum genome and the CT1040 gene product, N-Me-BSH synthase, were required for N-Me-BSH synthesis. N-Me-BSH was found in all Chlorobiaceae examined as well as Polaribacter sp. strain MED152, a member of the Bacteroidetes A comparative genomic analysis indicated that BSH/N-Me-BSH is synthesized not only by members of the Chlorobiaceae , Bacteroidetes , Deinococcus-Thermus , and Firmicutes but also by Acidobacteria , Chlamydiae , Gemmatimonadetes , and Proteobacteria. Thus, BSH and derivatives appear to be the most broadly distributed LMW thiols in biology. IMPORTANCE Low-molecular-weight thiols are key metabolites that participate in many basic cellular processes: central metabolism, detoxification, and oxidative stress resistance. Here we describe a new thiol, N-methyl-bacillithiol, found in an anaerobic phototrophic bacterium and identify a gene that is responsible for its synthesis from bacillithiol, the main thiol metabolite in many Gram-positive bacteria. We show that the presence or absence of this gene in a sequenced genome accurately predicts thiol content in distantly related bacteria. On the basis of these results, we analyzed genome data and predict that bacillithiol and its derivatives are the most widely distributed thiol metabolites in biology., (Copyright © 2018 Hiras et al.)- Published
- 2018
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23. Autistic-like traits in children are associated with enhanced performance in a qualitative visual working memory task.
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Hamilton CJ, Mammarella IC, and Giofrè D
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- Child, Evaluation Studies as Topic, Female, Humans, Individuality, Male, Phenotype, Photic Stimulation methods, Task Performance and Analysis, United Kingdom, Autism Spectrum Disorder physiopathology, Memory, Short-Term physiology
- Abstract
Prior research has suggested that individuals with Autism Spectrum Disorders (ASD) demonstrate heterogeneity in cognitive efficacy, challenged executive resources but efficient visual processing. These contrasts lead to opposing predictions about visuospatial working memory competency in both ASD and the broader autism phenotype (BAP); compromised by constrained executive processes, but potentially scaffolded by effective visual representation. It is surprising therefore, that there is a paucity of visual working memory (VWM) research in both the ASD and BAP populations, which have focused upon the visual features of the to-be-remembered stimulus. We assessed whether individual differences in VWM were associated with autistic-like traits (ALTs) in the BAP. About 76 children carried out the Visual Just Noticeable Difference task, designed to measure high fidelity feature representation within VWM. ALTs were measured with the Children's Empathy Quotient and Systemizing Quotient. Analyses revealed a significant positive relationship between Systemizing and VWM performance. This complements ASD studies in visual processing and highlights the need for further research on the working memory-long-term memory interface in ASD and BAP populations. Autism Research 2018, 11: 1494-1499. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: This study was interested in how well children with high levels of autistic-like traits (ALTs) carry out a task which involved memorizing, for brief time, the precise size of colored shapes. The results suggested that children with high levels of ALTs performed the task relatively well. This finding is in contrast to many previous studies suggest that ALTs are associated with poor memory, and suggests that future research needs to look more finely at how individuals carry out these tasks., (© 2018 International Society for Autism Research, Wiley Periodicals, Inc.)
- Published
- 2018
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24. Worsening Choreoathetosis in Huntington's Disease with Fluoxetine, Lisdexamfetamine, and Melatonin: A Case Report.
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Hamilton CJ, Timmer TK, Munjal RC, Cardozo-Pelaez F, and Mcgrane IR
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Cognitive, affective, and sleep disturbances can be found in patients with Huntington's disease (HD), and medications used to treat these HD-related sequela can also impact HD-related movement disorders. We present the case of a 52-year-old Caucasian man with previously undiagnosed HD who exhibited significant choreoathetoid movements that improved with discontinuation of fluoxetine and lisdexamfetamine upon hospital admission. Following diagnosis of HD through genetic testing, he was administered 5mg of oral melatonin on two consecutive evenings, which resulted in worsening choreoathetosis. We calculated Naranjo adverse event scores of 5, 5, and 2 for fluoxetine, lisdexamfetamine, and melatonin, respectively, based on our assessment, review of outpatient medical records, and available literature. We review the literature surrounding these possible adverse drug events and their mechanisms regarding dopaminergic modulation in early-middle stages of HD. Our report indicates that caution should be exercised when initiating psychostimulants, fluoxetine, and melatonin in patients with early-middle stage HD. Screening for HD might be warranted for patients who develop choreoathetosis after initiation of the aforementioned medications. We recommend ascertaining baseline level of chorea before initiating these medications in patients with known HD and closely monitoring for exacerbation during therapy., Competing Interests: FUNDING:No funding was provided for this article DISCLOSURES:The authors report no conflicts of interest relevant to the content of this article.
- Published
- 2018
25. Mass spectrometric detection of iron nitrosyls, sulfide oxidation and mycothiolation during nitrosylation of the NO sensor [4Fe-4S] NsrR.
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Crack JC, Hamilton CJ, and Le Brun NE
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The bacterial nitric oxide (NO)-sensing transcriptional regulator NsrR binds a [4Fe-4S] cluster that enables DNA-binding and thus repression of the cell's NO stress response. Upon exposure to NO, the cluster undergoes a complex nitrosylation reaction resulting in a mixture of iron-nitrosyl species, which spectroscopic studies have indicated are similar to well characterized low molecular weight dinitrosyl iron complex (DNIC), Roussin's Red Ester (RRE) and Roussin's Black Salt (RBS). Here we report mass spectrometric studies that enable the unambiguous identification of NsrR-bound RRE-type species, including a persulfide bound form that results from the oxidation of cluster sulfide. In the presence of the low molecular weight thiols glutathione and mycothiol, glutathionylated and mycothiolated forms of NsrR were readily formed.
- Published
- 2018
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26. Protein S-Bacillithiolation Functions in Thiol Protection and Redox Regulation of the Glyceraldehyde-3-Phosphate Dehydrogenase Gap in Staphylococcus aureus Under Hypochlorite Stress.
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Imber M, Huyen NTT, Pietrzyk-Brzezinska AJ, Loi VV, Hillion M, Bernhardt J, Thärichen L, Kolšek K, Saleh M, Hamilton CJ, Adrian L, Gräter F, Wahl MC, and Antelmann H
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- Bacterial Proteins genetics, Cysteine metabolism, GTPase-Activating Proteins chemistry, GTPase-Activating Proteins metabolism, Glucosamine metabolism, Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) chemistry, Humans, Hydrogen Peroxide metabolism, Hypochlorous Acid toxicity, Protein Conformation drug effects, Staphylococcus aureus genetics, Staphylococcus aureus pathogenicity, Stress, Physiological drug effects, Stress, Physiological genetics, Bacterial Proteins metabolism, Cysteine analogs & derivatives, Glucosamine analogs & derivatives, Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) metabolism, Staphylococcus aureus metabolism
- Abstract
Aims: Bacillithiol (BSH) is the major low-molecular-weight thiol of the human pathogen Staphylococcus aureus. In this study, we used OxICAT and Voronoi redox treemaps to quantify hypochlorite-sensitive protein thiols in S. aureus USA300 and analyzed the role of BSH in protein S-bacillithiolation., Results: The OxICAT analyses enabled the quantification of 228 Cys residues in the redox proteome of S. aureus USA300. Hypochlorite stress resulted in >10% increased oxidation of 58 Cys residues (25.4%) in the thiol redox proteome. Among the highly oxidized sodium hypochlorite (NaOCl)-sensitive proteins are five S-bacillithiolated proteins (Gap, AldA, GuaB, RpmJ, and PpaC). The glyceraldehyde-3-phosphate (G3P) dehydrogenase Gap represents the most abundant S-bacillithiolated protein contributing 4% to the total Cys proteome. The active site Cys151 of Gap was very sensitive to overoxidation and irreversible inactivation by hydrogen peroxide (H
2 O2 ) or NaOCl in vitro. Treatment with H2 O2 or NaOCl in the presence of BSH resulted in reversible Gap inactivation due to S-bacillithiolation, which could be regenerated by the bacilliredoxin Brx (SAUSA300_1321) in vitro. Molecular docking was used to model the S-bacillithiolated Gap active site, suggesting that formation of the BSH mixed disulfide does not require major structural changes. Conclusion and Innovation: Using OxICAT analyses, we identified 58 novel NaOCl-sensitive proteins in the pathogen S. aureus that could play protective roles against the host immune defense and include the glycolytic Gap as major target for S-bacillithiolation. S-bacillithiolation of Gap did not require structural changes, but efficiently functions in redox regulation and protection of the active site against irreversible overoxidation in S. aureus. Antioxid. Redox Signal. 28, 410-430.- Published
- 2018
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27. Older Adults Benefit from Symmetry, but Not Semantic Availability, in Visual Working Memory.
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Hamilton CJ, Brown LA, and Rossi-Arnaud C
- Abstract
Visual working memory exhibits age effects that are amongst the largest observed in the cognitive aging literature. In this research we investigated whether or not older adults can benefit from visual symmetry and semantic availability, as young adults typically do. Visual matrix pattern tasks varied in terms of the perceptual factor of symmetry (Experiment 1), as well as the availability of visual semantics, or long-term memory (LTM; Experiment 2). In Experiment 1, within a visual memory span protocol, four matrix pattern sets were employed with discrete symmetry characteristics; random, vertical, horizontal, and diagonal symmetry. Encoding time was 3 s with a 2 s maintenance interval. The findings indicated a significant difference in span level across age groups for all of the symmetry variants. More importantly, both younger and older adults could take advantage of symmetry in the matrix array in order to significantly improve task performance. In Experiment 2, two visual matrix task sets were used, with visual arrays of either low or high semantic availability (i.e., they contained stimuli with recognizable shapes that allow for LTM support). Encoding duration was 3 s with a 1 s retention interval. Here, the older adult sample was significantly impaired in span performance with both variants of the task. However, only the younger adult participants could take advantage of visual semantics. These findings show that, in the context of overall impairment in individual task performance, older adults remain capable of employing the perceptual cue of symmetry in order to improve visual working memory task performance. However, they appear less able, within this protocol, to recruit visual semantics in order to scaffold performance.
- Published
- 2018
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28. Real-Time Imaging of the Bacillithiol Redox Potential in the Human Pathogen Staphylococcus aureus Using a Genetically Encoded Bacilliredoxin-Fused Redox Biosensor.
- Author
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Loi VV, Harms M, Müller M, Huyen NTT, Hamilton CJ, Hochgräfe F, Pané-Farré J, and Antelmann H
- Subjects
- Bacterial Proteins genetics, Cysteine deficiency, Cysteine genetics, Cysteine metabolism, Glucosamine deficiency, Glucosamine genetics, Glucosamine metabolism, Green Fluorescent Proteins genetics, Green Fluorescent Proteins metabolism, Oxidation-Reduction, Staphylococcus aureus genetics, Time Factors, Bacterial Proteins metabolism, Biosensing Techniques, Cysteine analogs & derivatives, Glucosamine analogs & derivatives, Staphylococcus aureus metabolism
- Abstract
Aims: Bacillithiol (BSH) is utilized as a major thiol-redox buffer in the human pathogen Staphylococcus aureus. Under oxidative stress, BSH forms mixed disulfides with proteins, termed as S-bacillithiolation, which can be reversed by bacilliredoxins (Brx). In eukaryotes, glutaredoxin-fused roGFP2 biosensors have been applied for dynamic live imaging of the glutathione redox potential. Here, we have constructed a genetically encoded bacilliredoxin-fused redox biosensor (Brx-roGFP2) to monitor dynamic changes in the BSH redox potential in S. aureus., Results: The Brx-roGFP2 biosensor showed a specific and rapid response to low levels of bacillithiol disulfide (BSSB) in vitro that required the active-site Cys of Brx. Dynamic live imaging in two methicillin-resistant S. aureus (MRSA) USA300 and COL strains revealed fast and dynamic responses of the Brx-roGFP2 biosensor under hypochlorite and hydrogen peroxide (H
2 O2 ) stress and constitutive oxidation of the probe in different BSH-deficient mutants. Furthermore, we found that the Brx-roGFP2 expression level and the dynamic range are higher in S. aureus COL compared with the USA300 strain. In phagocytosis assays with THP-1 macrophages, the biosensor was 87% oxidized in S. aureus COL. However, no changes in the BSH redox potential were measured after treatment with different antibiotics classes, indicating that antibiotics do not cause oxidative stress in S. aureus. Conclusion and Innovation: This Brx-roGFP2 biosensor catalyzes specific equilibration between the BSH and roGFP2 redox couples and can be applied for dynamic live imaging of redox changes in S. aureus and other BSH-producing Firmicutes. Antioxid. Redox Signal. 26, 835-848.- Published
- 2017
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29. Statement of concern re: The effects of organic nitrates on osteoporosis: a systematic review.
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Jamal SA, Reid LS, and Hamilton CJ
- Published
- 2017
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30. Think Yellow and Keep Green-Role of Sulfanes from Garlic in Agriculture.
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Anwar A, Gould E, Tinson R, Groom M, and Hamilton CJ
- Abstract
Reactive sulfur species from garlic have long been renowned for their health benefits and antimicrobial properties. In agriculture the subject matter is now gathering momentum in the search for new bio-pesticides to addressing emerging environmental concerns and tighter restrictions on the use of many conventional chemical pesticides. Although the precise modes of action of these garlic-derived bioactives is complex, recent research has provided a number of new insights that deepen our understanding of garlic-derived products, such as garlic extracts and oils. Herein, their activity against various crop-damaging pests is reviewed. In many cases, there seems to be a broad range of activity associated with the sulfur-containing compounds derived from Allium species, which manifests itself in diverse insecticidal, antifungal, and nematicidal activities. These activities open a new understanding to develop this natural chemistry as a "green pesticide".
- Published
- 2016
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31. How does intentionality of encoding affect memory for episodic information?
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Craig M, Butterworth K, Nilsson J, Hamilton CJ, Gallagher P, and Smulders TV
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- Adult, Awareness, Cognition, Female, Goals, Humans, Male, Mental Recall, Psychological Tests, Spatial Memory, Time Factors, Intention, Memory, Episodic
- Abstract
Episodic memory enables the detailed and vivid recall of past events, including target and wider contextual information. In this paper, we investigated whether/how encoding intentionality affects the retention of target and contextual episodic information from a novel experience. Healthy adults performed (1) a What-Where-When (WWW) episodic memory task involving the hiding and delayed recall of a number of items (what) in different locations (where) in temporally distinct sessions (when) and (2) unexpected tests probing memory for wider contextual information from the WWW task. Critically, some participants were informed that memory for WWW information would be subsequently probed (intentional group), while this came as a surprise for others (incidental group). The probing of contextual information came as a surprise for all participants. Participants also performed several measures of episodic and nonepisodic cognition from which common episodic and nonepisodic factors were extracted. Memory for target (WWW) and contextual information was superior in the intentional group compared with the incidental group. Memory for target and contextual information was unrelated to factors of nonepisodic cognition, irrespective of encoding intentionality. In addition, memory for target information was unrelated to factors of episodic cognition. However, memory for wider contextual information was related to some factors of episodic cognition, and these relationships differed between the intentional and incidental groups. Our results lead us to propose the hypothesis that intentional encoding of episodic information increases the coherence of the representation of the context in which the episode took place. This hypothesis remains to be tested., (© 2016 Craig et al.; Published by Cold Spring Harbor Laboratory Press.)
- Published
- 2016
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32. Thiol Redox and pKa Properties of Mycothiol, the Predominant Low-Molecular-Weight Thiol Cofactor in the Actinomycetes.
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Sharma SV, Van Laer K, Messens J, and Hamilton CJ
- Subjects
- Actinobacteria chemistry, Coenzymes chemistry, Hydrogen-Ion Concentration, Molecular Conformation, Molecular Weight, Oxidation-Reduction, Actinobacteria metabolism, Coenzymes metabolism, Cysteine chemistry, Cysteine metabolism, Glycopeptides chemistry, Glycopeptides metabolism, Inositol chemistry, Inositol metabolism, Sulfhydryl Compounds chemistry, Sulfhydryl Compounds metabolism
- Abstract
The thiol pKa and standard redox potential of mycothiol, the major low-molecular-weight thiol cofactor in the actinomycetes, are reported. The measured standard redox potential reveals substantial discrepancies in one or more of the other previously measured intracellular parameters that are relevant to mycothiol redox biochemistry., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
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- 2016
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33. Mass spectrometry of B. subtilis CopZ: Cu(i)-binding and interactions with bacillithiol.
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Kay KL, Hamilton CJ, and Le Brun NE
- Subjects
- Bacillus subtilis growth & development, Binding Sites, Cysteine metabolism, Glucosamine metabolism, Models, Molecular, Protein Binding, Bacillus subtilis metabolism, Bacterial Proteins metabolism, Copper metabolism, Cysteine analogs & derivatives, Glucosamine analogs & derivatives, Mass Spectrometry methods, Molecular Chaperones metabolism
- Abstract
CopZ from Bacillus subtilis is a well-studied member of the highly conserved family of Atx1-like copper chaperones. It was previously shown via solution and crystallographic studies to undergo Cu(i)-mediated dimerisation, where the CopZ dimer can bind between one and four Cu(i) ions. However, these studies could not provide information about the changing distribution of species at increasing Cu(i) levels. To address this, electrospray ionisation mass spectrometry using soft ionisation was applied to CopZ under native conditions. Data revealed folded, monomeric CopZ in apo- and Cu(i)-bound forms, along with Cu(i)-bound dimeric forms of CopZ at higher Cu(i) loading. Cu4(CopZ)2 was the major dimeric species at loadings >1 Cu(i)/CopZ, indicating the cooperative formation of the tetranuclear Cu(i)-bound species. As the principal low molecular weight thiol in B. subtilis, bacillithiol (BSH) may play a role in copper homeostasis. Mass spectrometry showed that increasing BSH led to a reduction in Cu(i)-bound dimeric forms, and the formation of S-bacillithiolated apo-CopZ and BSH adducts of Cu(i)-bound forms of CopZ, where BSH likely acts as a Cu(i) ligand. These data, along with the high affinity of BSH for Cu(i), determined here to be β2(BSH) = ∼4 × 10(17) M(-2), are consistent with a role for BSH alongside CopZ in buffering cellular Cu(i) levels. Here, mass spectrometry provides a high resolution overview of CopZ-Cu(i) speciation that cannot be obtained from less discriminating solution-phase methods, thus illustrating the potential for the wider application of this technique to studies of metal-protein interactions.
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- 2016
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34. Multispecialty screening, brief intervention, and referral to treatment (SBIRT) training in an academic medical center: Resident training experience across specialties.
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Clemence AJ, Balkoski VI, Schaefer BM, Lee M, Bromley N, Maisonneuve IM, Hamilton CJ, Lukowitsky MR, Poston J, Hall S, Pieterse P, Antonikowski A, and Glick SD
- Subjects
- Clinical Competence, Curriculum, Female, Humans, Male, Medicine, Program Evaluation, Psychotherapy, Brief education, Substance-Related Disorders diagnosis, Academic Medical Centers, Education, Medical, Graduate methods, Internship and Residency, Referral and Consultation, Substance-Related Disorders therapy
- Abstract
Background: The Substance Abuse and Mental Health Services Administration (SAMHSA) has recently begun to fund programs that train medical residents on how to utilize an evidence-based validated system known as screening, brief intervention, and referral to treatment (SBIRT) for providing early detection and brief treatment of unhealthy substance use. This paper investigates training outcomes of multispecialty SBIRT training at one such program at Albany Medical Center (AMC), one of the initial SAMHSA grantees., Methods: Training outcomes were measured across 3 domains of learning: trainee satisfaction, acquired knowledge, and perceived usefulness. The authors explored differences in learning experience by postgraduate year and by specialty., Results: Overall, residents were highly satisfied with the training, and learning outcomes met objectives. Residents' ratings of usefulness did not vary by program year. However, the results indicate that relative to residents in other programs, residents in psychiatry and pediatrics found the training components significantly more useful, whereas emergency medicine residents found training components to have less utility. Residents who found the training relevant to their daily work were more satisfied and more receptive to SBIRT training overall, which may help explain difference scores by program., Conclusions: Residents were highly satisfied with SBIRT skills training, although ratings of usefulness varied by residency program. Specialization by program and on-site modeling by senior faculty may enhance trainee satisfaction and perceived usefulness.
- Published
- 2016
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35. Residents' experience of screening, brief intervention, and referral to treatment (SBIRT) as a clinical tool following practical application: A mixed-methods study.
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Clemence AJ, Balkoski VI, Lee M, Poston J, Schaefer BM, Maisonneuve IM, Bromley N, Lukowitsky M, Pieterse P, Antonikowski A, Hamilton CJ, Hall S, and Glick SD
- Subjects
- Attitude of Health Personnel, Clinical Competence, Humans, Education, Medical, Graduate methods, Internship and Residency statistics & numerical data, Referral and Consultation, Substance Abuse Detection, Substance-Related Disorders diagnosis, Substance-Related Disorders therapy
- Abstract
Background: Screening, brief intervention, and referral to treatment (SBIRT), an evidence-based validated system for providing early detection and brief treatment of substance use disorders, has been widely used in the training of medical residents across specialties at a number of sites. This article investigates the effectiveness of SBIRT training during short-term follow-up at Albany Medical Center, one of the initial Substance Abuse and Mental Health Services Administration (SAMHSA) grantees., Methods: Training outcomes were measured by training satisfaction following opportunities to apply SBIRT skills in clinical work, the rate at which these techniques were applied in clinical work, and the degree to which residents felt that the SBIRT training provided skills that were applicable to their practice. We examined differences in learning experience by postgraduate year and by program, and conducted a qualitative analysis in a convergent parallel mixed-methods design to elucidate barriers encountered by residents upon using SBIRT techniques in clinical practice., Results: Residents remained highly satisfied with the training at 4-month follow-up, with 80.1% reporting that they had used SBIRT skills in their clinical work. Use of SBIRT techniques was high at 6-month follow-up as well, with 85.9% of residents reporting that they regularly screened their patients for substance use, 74.4% reporting that they had applied brief intervention techniques, and 78.2% indicating that SBIRT training had made them overall more effective in helping patients with substance use issues. Differences in application rates and satisfaction were found by specialty. Qualitative analyses indicated that residents encountered patient readiness and specific contextual factors, such as time constraints, externally imposed values, and clinical norms, as barriers to implementation., Conclusions: Despite encountering obstacles such as time constraints and patient readiness, residents utilized many of the skills they had learned during SBIRT training in clinical practice and reported finding these skills useful in their management of patients with substance use issues.
- Published
- 2016
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36. Notice of Retraction: Jamal SA, et al. Effect of Nitroglycerin Ointment on Bone Density and Strength in Postmenopausal Women: A Randomized Trial. JAMA. 2011;305(8):800-807.
- Author
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Eastell R, Hamilton CJ, and Cummings SR
- Published
- 2016
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37. The transcriptome of Euglena gracilis reveals unexpected metabolic capabilities for carbohydrate and natural product biochemistry.
- Author
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O'Neill EC, Trick M, Hill L, Rejzek M, Dusi RG, Hamilton CJ, Zimba PV, Henrissat B, and Field RA
- Subjects
- Ascorbic Acid biosynthesis, Genome, Protozoan, Metabolic Engineering, Protozoan Proteins chemistry, Protozoan Proteins metabolism, Vitamin A biosynthesis, Vitamin E biosynthesis, Euglena gracilis genetics, Gene Expression Profiling methods, Protozoan Proteins genetics, Sequence Analysis, RNA methods
- Abstract
Euglena gracilis is a highly complex alga belonging to the green plant line that shows characteristics of both plants and animals, while in evolutionary terms it is most closely related to the protozoan parasites Trypanosoma and Leishmania. This well-studied organism has long been known as a rich source of vitamins A, C and E, as well as amino acids that are essential for the human diet. Here we present de novo transcriptome sequencing and preliminary analysis, providing a basis for the molecular and functional genomics studies that will be required to direct metabolic engineering efforts aimed at enhancing the quality and quantity of high value products from E. gracilis. The transcriptome contains over 30,000 protein-encoding genes, supporting metabolic pathways for lipids, amino acids, carbohydrates and vitamins, along with capabilities for polyketide and non-ribosomal peptide biosynthesis. The metabolic and environmental robustness of Euglena is supported by a substantial capacity for responding to biotic and abiotic stress: it has the capacity to deploy three separate pathways for vitamin C (ascorbate) production, as well as producing vitamin E (α-tocopherol) and, in addition to glutathione, the redox-active thiols nor-trypanothione and ovothiol.
- Published
- 2015
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38. Sulforaphane Protects the Liver against CdSe Quantum Dot-Induced Cytotoxicity.
- Author
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Wang W, He Y, Yu G, Li B, Sexton DW, Wileman T, Roberts AA, Hamilton CJ, Liu R, Chao Y, Shan Y, and Bao Y
- Subjects
- Adenine analogs & derivatives, Adenine pharmacology, Androstadienes pharmacology, Animals, Autophagy drug effects, Cell Death drug effects, Cell Line, Gene Knockdown Techniques, Glutathione metabolism, Humans, Intracellular Signaling Peptides and Proteins metabolism, Intracellular Space metabolism, Kelch-Like ECH-Associated Protein 1, Liver drug effects, Liver metabolism, Metallothionein genetics, Metallothionein metabolism, Mice, Inbred ICR, NF-E2-Related Factor 2 metabolism, Protective Agents pharmacology, RNA, Messenger genetics, RNA, Messenger metabolism, Sulfoxides, Transcription, Genetic drug effects, Wortmannin, Cadmium Compounds toxicity, Isothiocyanates pharmacology, Liver pathology, Quantum Dots toxicity, Selenium Compounds toxicity
- Abstract
The potential cytotoxicity of cadmium selenide (CdSe) quantum dots (QDs) presents a barrier to their use in biomedical imaging or as diagnostic and therapeutic agents. Sulforaphane (SFN) is a chemoprotective compound derived from cruciferous vegetables which can up-regulate antioxidant enzymes and induce apoptosis and autophagy. This study reports the effects of SFN on CdSe QD-induced cytotoxicity in immortalised human hepatocytes and in the livers of mice. CdSe QDs induced dose-dependent cell death in hepatocytes with an IC50 = 20.4 μM. Pre-treatment with SFN (5 μM) increased cell viability in response to CdSe QDs (20 μM) from 49.5 to 89.3%. SFN induced a pro-oxidant effect characterized by depletion of intracellular reduced glutathione during short term exposure (3-6 h), followed by up-regulation of antioxidant enzymes and glutathione levels at 24 h. SFN also caused Nrf2 translocation into the nucleus, up-regulation of antioxidant enzymes and autophagy. siRNA knockdown of Nrf2 suggests that the Nrf2 pathway plays a role in the protection against CdSe QD-induced cell death. Wortmannin inhibition of SFN-induced autophagy significantly suppressed the protective effect of SFN on CdSe QD-induced cell death. Moreover, the role of autophagy in SFN protection against CdSe QD-induced cell death was confirmed using mouse embryonic fibroblasts lacking ATG5. CdSe QDs caused significant liver damage in mice, and this was decreased by SFN treatment. In conclusion, SFN attenuated the cytotoxicity of CdSe QDs in both human hepatocytes and in the mouse liver, and this protection was associated with the induction of Nrf2 pathway and autophagy.
- Published
- 2015
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39. NsrR from Streptomyces coelicolor is a nitric oxide-sensing [4Fe-4S] cluster protein with a specialized regulatory function.
- Author
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Crack JC, Munnoch J, Dodd EL, Knowles F, Al Bassam MM, Kamali S, Holland AA, Cramer SP, Hamilton CJ, Johnson MK, Thomson AJ, Hutchings MI, and Le Brun NE
- Subjects
- Bacterial Proteins genetics, DNA-Binding Proteins genetics, Iron-Sulfur Proteins genetics, Promoter Regions, Genetic physiology, Regulon physiology, Streptomyces coelicolor genetics, Bacterial Proteins metabolism, DNA-Binding Proteins metabolism, Iron-Sulfur Proteins metabolism, Nitric Oxide metabolism, Streptomyces coelicolor metabolism
- Abstract
The Rrf2 family transcription factor NsrR controls expression of genes in a wide range of bacteria in response to nitric oxide (NO). The precise form of the NO-sensing module of NsrR is the subject of controversy because NsrR proteins containing either [2Fe-2S] or [4Fe-4S] clusters have been observed previously. Optical, Mössbauer, resonance Raman spectroscopies and native mass spectrometry demonstrate that Streptomyces coelicolor NsrR (ScNsrR), previously reported to contain a [2Fe-2S] cluster, can be isolated containing a [4Fe-4S] cluster. ChIP-seq experiments indicated that the ScNsrR regulon is small, consisting of only hmpA1, hmpA2, and nsrR itself. The hmpA genes encode NO-detoxifying flavohemoglobins, indicating that ScNsrR has a specialized regulatory function focused on NO detoxification and is not a global regulator like some NsrR orthologues. EMSAs and DNase I footprinting showed that the [4Fe-4S] form of ScNsrR binds specifically and tightly to an 11-bp inverted repeat sequence in the promoter regions of the identified target genes and that DNA binding is abolished following reaction with NO. Resonance Raman data were consistent with cluster coordination by three Cys residues and one oxygen-containing residue, and analysis of ScNsrR variants suggested that highly conserved Glu-85 may be the fourth ligand. Finally, we demonstrate that some low molecular weight thiols, but importantly not physiologically relevant thiols, such as cysteine and an analogue of mycothiol, bind weakly to the [4Fe-4S] cluster, and exposure of this bound form to O2 results in cluster conversion to the [2Fe-2S] form, which does not bind to DNA. These data help to account for the observation of [2Fe-2S] forms of NsrR., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
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- 2015
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40. Total motile sperm count: a better indicator for the severity of male factor infertility than the WHO sperm classification system.
- Author
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Hamilton JA, Cissen M, Brandes M, Smeenk JM, de Bruin JP, Kremer JA, Nelen WL, and Hamilton CJ
- Subjects
- Adult, Female, Humans, Longitudinal Studies, Male, Prognosis, Reproducibility of Results, Semen Analysis, Severity of Illness Index, Spermatozoa, World Health Organization, Infertility, Male classification, Infertility, Male diagnosis, Sperm Count, Sperm Motility
- Abstract
Study Question: Does the prewash total motile sperm count (TMSC) have a better predictive value for spontaneous ongoing pregnancy (SOP) than the World Health Organization (WHO) classification system?, Summary Answer: The prewash TMSC shows a better correlation with the spontaneous ongoing pregnancy rate (SOPR) than the WHO 2010 classification system., What Is Known Already: According to the WHO classification system, an abnormal semen analysis can be diagnosed as oligozoospermia, astenozoospermia, teratozoospermia or combinations of these and azoospermia. This classification is based on the fifth percentile cut-off values of a cohort of 1953 men with proven fertility. Although this classification suggests accuracy, the relevance for the prognosis of an infertile couple and the choice of treatment is questionable. The TMSC is obtained by multiplying the sample volume by the density and the percentage of A and B motility spermatozoa., Study Design, Size, Duration: We analyzed data from a longitudinal cohort study among unselected infertile couples who were referred to three Dutch hospitals between January 2002 and December 2006. Of the total cohort of 2476 infertile couples, only the couples with either male infertility as a single diagnosis or unexplained infertility were included (n = 1177) with a follow-up period of 3 years., Participants/materials, Setting, Methods: In all couples a semen analysis was performed. Based on the best semen analysis if more tests were performed, couples were grouped according to the WHO classification system and the TMSC range, as described in the Dutch national guidelines for male infertility. The primary outcome measure was the SOPR, which occurred before, during or after treatments, including expectant management, intrauterine insemination, in vitro fertilization or intracytoplasmic sperm injection. After adjustment for the confounding factors (female and male age, duration and type of infertility and result of the postcoital test) the odd ratios (ORs) for risk of SOP for each WHO and TMSC group were calculated. The couples with unexplained infertility were used as reference., Main Results and the Role of Chance: A total of 514 couples did and 663 couples did not achieve a SOP. All WHO groups have a lower SOPR compared with the unexplained group (ORs varying from 0.136 to 0.397). Comparing the couples within the abnormal WHO groups, there are no significant differences in SOPR, except when oligoasthenoteratozoospermia is compared with asthenozoospermia [OR 0.501 (95% CI 0.311-0.809)] and teratozoospermia [OR 0.499 (95% CI: 0.252-0.988)], and oligoasthenozoospermia is compared with asthenozoospermia [OR 0.572 (95% CI: 0.373-0.877)]. All TMSC groups have a significantly lower SOPR compared with the unexplained group (ORs varying from 0.171 to 0.461). Couples with a TMSC of <1 × 10(6) and 1-5 × 10(6) have significantly lower SOPR compared with couples with a TMSC of 5-10 × 10(6) [respectively, OR 0.371 (95% CI: 0.215-0.64) and OR 0.505 (95% CI: 0.307-0.832)]., Limitations, Reason for Caution: To include all SOPs during the follow-up period of 3 years, couples were not censured at the start of treatment., Wider Implications of the Findings: Roughly, three prognostic groups can be discerned: couples with a TMSC <5, couples with a TMSC between 5 and 20 and couples with a TMSC of more than 20 × 10(6) spermatozoa. We suggest using TMSC as the method of choice to express severity of male infertility., Study Funding/competing Interests: None., (© The Author 2015. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2015
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41. How long should we continue clomiphene citrate in anovulatory women?
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Weiss NS, Braam S, König TE, Hendriks ML, Hamilton CJ, Smeenk JM, Koks CA, Kaaijk EM, Hompes PG, Lambalk CB, van der Veen F, Mol BW, and van Wely M
- Subjects
- Adult, Clomiphene administration & dosage, Databases, Factual, Drug Administration Schedule, Female, Fertility Agents, Female administration & dosage, Humans, Pregnancy, Pregnancy Rate, Retrospective Studies, Clomiphene therapeutic use, Fertility Agents, Female therapeutic use, Ovulation Induction methods
- Abstract
Study Question: What is the effectiveness of continued treatment with clomiphene citrate (CC) in women with World Health Organization (WHO) type II anovulation who have had at least six ovulatory cycles with CC but did not conceive?, Summary Answer: When women continued CC after six treatment cycles, the cumulative incidence rate of the ongoing pregnancy rate was 54% (95% CI 37-78%) for cycles 7-12., What Is Known Already: If women with WHO type II anovulation fail to conceive with CC within six ovulatory cycles, guidelines advise switching to gonadotrophins, which have a high risk of multiple gestation and are expensive. It is however not clear what success rate could be achieved by continued treatment with CC., Study Design, Size, Duration: We performed a retrospective cohort study of women with WHO II anovulation who visited the fertility clinics of five hospitals in the Netherlands between 1994 and 2010. We included women treated with CC who had had at least six ovulatory cycles without successful conception (n = 114) after which CC was continued using dosages varying from 50 to 150 mg per day for 5 days., Participants/materials, Setting, Methods: Follow-up was a total of 12 treatment cycles. Primary outcome was the cumulative incidence rate of an ongoing pregnancy at the end of treatment., Main Results and the Role of Chance: We recruited 114 women that had ovulated on CC for at least six cycles but had not conceived. Of these 114 women, 35 (31%) had an ongoing pregnancy resulting in a cumulative incidence rate of an ongoing pregnancy of 54% after 7-12 treatment cycles with CC., Limitations, Reasons for Caution: Limitations of our study are its retrospective approach., Wider Implications of the Findings: Randomized trials comparing continued treatment with CC with the relatively established second line treatment with gonadotrophins are justified. In the meantime, we suggest to only begin this less convenient and more expensive treatment for women who do not conceive after 12 ovulatory cycles with CC., Study Funding/competing Interests: None., Trial Registration Number: Not applicable., (© The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)
- Published
- 2014
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42. Long-term ongoing pregnancy rate and mode of conception after a positive and negative post-coital test.
- Author
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Hessel M, Brandes M, de Bruin JP, Bots RS, Kremer JA, Nelen WL, and Hamilton CJ
- Subjects
- Adolescent, Adult, Female, Humans, Male, Middle Aged, Predictive Value of Tests, Pregnancy, Prognosis, Retrospective Studies, Young Adult, Fertilization, Infertility therapy, Pregnancy Rate
- Abstract
Objective: Many fertility clinics have decided to abolish the post-coital test. Yet, it is a significant factor in prognostic models that predict the spontaneous pregnancy rate within one year. The aim of this study was to evaluate (1) the long-term outcome of infertile couples with a positive or a negative post-coital test during their fertility work-up and (2) the contribution of the different modes of conception., Design: Retrospective cohort study., Setting: Three fertility clinics in the Netherlands, of which two are secondary care training hospitals and is a one tertiary care academic training hospital., Population: 2476 newly referred infertile couples, where a post-coital test was performed in 1624 couples., Methods: After basic fertility work-up, couples were treated according to the national treatment protocols., Main Outcome Measures: Spontaneous and overall ongoing pregnancy rate., Results: The spontaneous and overall ongoing pregnancy rates after three years were 37.7 and 77.5% after a positive post-coital test compared with 26.9 and 68.8% after a negative test (p < 0.001). Even in couples with severe male factor infertility (total motile sperm count <3) (p = 0.005) and mild male factor infertility (total motile sperm count 3-20) (p < 0.001), there was a significantly higher spontaneous ongoing pregnancy rate, justifying expectant management., Conclusion: After a follow-up of three years a positive post-coital test is still associated with a higher spontaneous and a higher overall ongoing pregnancy rate, even in couples with severe male factor infertility., (© 2014 Nordic Federation of Societies of Obstetrics and Gynecology.)
- Published
- 2014
- Full Text
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43. Redox regulation in Bacillus subtilis: The bacilliredoxins BrxA(YphP) and BrxB(YqiW) function in de-bacillithiolation of S-bacillithiolated OhrR and MetE.
- Author
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Gaballa A, Chi BK, Roberts AA, Becher D, Hamilton CJ, Antelmann H, and Helmann JD
- Subjects
- Bacillus subtilis genetics, Cysteine metabolism, Disulfides metabolism, Glucosamine metabolism, Oxidative Stress, Sulfur metabolism, Bacillus subtilis metabolism, Bacterial Proteins metabolism, Cysteine analogs & derivatives, Glucosamine analogs & derivatives, Methyltransferases metabolism, Oxidation-Reduction, Repressor Proteins metabolism
- Abstract
Aims: In bacillithiol (BSH)-utilizing organisms, protein S-bacillithiolation functions as a redox switch in response to oxidative stress and protects critical Cys residues against overoxidation. In Bacillus subtilis, both the redox-sensing repressor OhrR and the methionine synthase MetE are redox controlled by S-bacillithiolation in vivo. Here, we identify pathways of protein de-bacillithiolation and test the hypothesis that YphP(BrxA) and YqiW(BrxB) act as bacilliredoxins (Brx) to remove BSH from OhrR and MetE mixed disulfides., Results: We present evidence that the BrxA and BrxB paralogs have de-bacillithiolation activity. This Brx activity results from attack of the amino-terminal Cys residue in a CGC motif on protein BSH-mixed disulfides. B. subtilis OhrR DNA-binding activity is eliminated by S-thiolation on its sole Cys residue. Both the BrxA and BrxB bacilliredoxins mediate de-bacillithiolation of OhrR accompanied by the transfer of BSH to the amino-terminal cysteine of their CGC active site motif. In vitro studies demonstrate that BrxB can restore DNA-binding activity to OhrR which is S-bacillithiolated, but not to OhrR that is S-cysteinylated. MetE is most strongly S-bacillithiolated at Cys719 in vitro and can be efficiently de-bacillithiolated by both BrxA and BrxB., Innovation and Conclusion: We demonstrate that BrxA and BrxB function in the reduction of BSH mixed protein disulfides with two natural substrates (MetE, OhrR). These results provide biochemical evidence for a new class of bacterial redox-regulatory proteins, the bacilliredoxins, which function analogously to glutaredoxins. Bacilliredoxins function in concert with other thiol-disulfide oxidoreductases to maintain redox homeostasis in response to disulfide stress conditions.
- Published
- 2014
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44. Spatial demonstratives and perceptual space: describing and remembering object location.
- Author
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Coventry KR, Griffiths D, and Hamilton CJ
- Subjects
- Adolescent, Adult, Cognition, Female, Humans, Male, Speech, Young Adult, Knowledge, Language, Mental Recall, Space Perception
- Abstract
Spatial demonstratives - terms including this and that - are among the most common words across all languages. Yet, there are considerable differences between languages in how demonstratives carve up space and the object characteristics they can refer to, challenging the idea that the mapping between spatial demonstratives and the vision and action systems is universal. In seven experiments we show direct parallels between spatial demonstrative usage in English and (non-linguistic) memory for object location, indicating close connections between the language of space and non-linguistic spatial representation. Spatial demonstrative choice in English and immediate memory for object location are affected by a range of parameters - distance, ownership, visibility and familiarity - that are lexicalized in the demonstrative systems of some other languages. The results support a common set of constraints on language used to talk about space and on (non-linguistic) spatial representation itself. Differences in demonstrative systems across languages may emerge from basic distinctions in the representation and memory for object location. In turn, these distinctions offer a building block from which non-spatial uses of demonstratives can develop., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2014
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45. Methylglyoxal resistance in Bacillus subtilis: contributions of bacillithiol-dependent and independent pathways.
- Author
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Chandrangsu P, Dusi R, Hamilton CJ, and Helmann JD
- Subjects
- Bacillus subtilis enzymology, Cysteine metabolism, Cytoplasm chemistry, Glucosamine metabolism, Hydrogen-Ion Concentration, Lactic Acid metabolism, Lactoylglutathione Lyase metabolism, Thiolester Hydrolases metabolism, Bacillus subtilis drug effects, Bacillus subtilis metabolism, Cysteine analogs & derivatives, Drug Resistance, Bacterial, Glucosamine analogs & derivatives, Metabolic Networks and Pathways, Pyruvaldehyde toxicity
- Abstract
Methylglyoxal (MG) is a toxic by-product of glycolysis that damages DNA and proteins ultimately leading to cell death. Protection from MG is often conferred by a glutathione-dependent glyoxalase pathway. However, glutathione is absent from the low-GC Gram-positive Firmicutes, such as Bacillus subtilis. The identification of bacillithiol (BSH) as the major low-molecular-weight thiol in the Firmicutes raises the possibility that BSH is involved in MG detoxification. Here, we demonstrate that MG can rapidly and specifically deplete BSH in cells, and we identify both BSH-dependent and BSH-independent MG resistance pathways. The BSH-dependent pathway utilizes glyoxalase I (GlxA, formerly YwbC) and glyoxalase II (GlxB, formerly YurT) to convert MG to d-lactate. The critical step in this pathway is the activation of the KhtSTU K(+) efflux pump by the S-lactoyl-BSH intermediate, which leads to cytoplasmic acidification. We show that cytoplasmic acidification is both necessary and sufficient for maximal protection from MG. Two additional MG detoxification pathways operate independent of BSH. The first involves three enzymes (YdeA, YraA and YfkM) which are predicted to be homologues of glyoxalase III that converts MG to d-lactate, and the second involves YhdN, previously shown to be a broad specificity aldo-keto reductase that converts MG to acetol., (© 2013 John Wiley & Sons Ltd.)
- Published
- 2014
- Full Text
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46. Genome-wide transcriptome and antioxidant analyses on gamma-irradiated phases of deinococcus radiodurans R1.
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Luan H, Meng N, Fu J, Chen X, Xu X, Feng Q, Jiang H, Dai J, Yuan X, Lu Y, Roberts AA, Luo X, Chen M, Xu S, Li J, Hamilton CJ, Fang C, and Wang J
- Subjects
- Bacterial Proteins genetics, Bacterial Proteins metabolism, DNA Repair, Deinococcus genetics, Deinococcus radiation effects, Metabolic Networks and Pathways genetics, Metabolomics, Principal Component Analysis, RNA, Bacterial genetics, RNA, Bacterial metabolism, Radiation Tolerance, Sequence Analysis, RNA, Antioxidants metabolism, Deinococcus metabolism, Gene Expression Regulation, Bacterial radiation effects, Transcriptome
- Abstract
Adaptation of D. radiodurans cells to extreme irradiation environments requires dynamic interactions between gene expression and metabolic regulatory networks, but studies typically address only a single layer of regulation during the recovery period after irradiation. Dynamic transcriptome analysis of D. radiodurans cells using strand-specific RNA sequencing (ssRNA-seq), combined with LC-MS based metabolite analysis, allowed an estimate of the immediate expression pattern of genes and antioxidants in response to irradiation. Transcriptome dynamics were examined in cells by ssRNA-seq covering its predicted genes. Of the 144 non-coding RNAs that were annotated, 49 of these were transfer RNAs and 95 were putative novel antisense RNAs. Genes differentially expressed during irradiation and recovery included those involved in DNA repair, degradation of damaged proteins and tricarboxylic acid (TCA) cycle metabolism. The knockout mutant crtB (phytoene synthase gene) was unable to produce carotenoids, and exhibited a decreased survival rate after irradiation, suggesting a role for these pigments in radiation resistance. Network components identified in this study, including repair and metabolic genes and antioxidants, provided new insights into the complex mechanism of radiation resistance in D. radiodurans.
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- 2014
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47. Heterogeneity in skeletal load adaptation points to a role for modeling in the pathogenesis of osteoporotic fracture.
- Author
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Hamilton CJ, Jamal SA, Beck TJ, Khaled AS, Adachi JD, Brown JP, and Davison KS
- Subjects
- Absorptiometry, Photon, Age Factors, Aged, Bone Density, Canada, Case-Control Studies, Cohort Studies, Female, Humans, Middle Aged, Risk Factors, Stress, Mechanical, Weight-Bearing physiology, Adaptation, Physiological physiology, Femur Neck physiopathology, Osteoporotic Fractures etiology
- Abstract
Genetic, environmental, or hormonal factors may cause heterogeneity in skeletal load response. Individuals with reduced sensitivity to load should require higher strains to generate an adaptive response, consequently have weaker bones and fracture more frequently. The purpose of our study was to determine if stresses (proportional to strains) at the femoral neck under equivalent loads were higher in women with a history of fractures compared with women without fractures. We studied postmenopausal women participating in the Canadian Multicentre Osteoporosis Study who had available hip structure analysis data from dual-energy X-ray absorptiometry scans (n = 2168). Women were categorized into 2 groups based on their number of self-reported fractures. We computed stress (megapascals) at the inferomedial margin of the femoral neck in a one-legged stance mode using a 2-dimensional engineering beam analysis. We used linear regression (SAS 9.3) to determine associations between stress, geometry parameters, and number of fractures. Postmenopausal women with 1 or more fractures had higher stress (2.6%), lower narrow neck bone mineral density (4.2%), cross-sectional area (3.9%), and section modulus (9.6%) than postmenopausal women without fractures (all p < 0.05). These findings provide evidence of heterogeneity in load response and suggest an important role for modeling in the pathogenesis of osteoporotic fracture., (Copyright © 2014 The International Society for Clinical Densitometry. Published by Elsevier Inc. All rights reserved.)
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- 2014
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48. Importance of bacillithiol in the oxidative stress response of Staphylococcus aureus.
- Author
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Posada AC, Kolar SL, Dusi RG, Francois P, Roberts AA, Hamilton CJ, Liu GY, and Cheung A
- Subjects
- Amidohydrolases deficiency, Analysis of Variance, Anti-Bacterial Agents pharmacology, Bacterial Proteins genetics, Cysteine genetics, Cysteine physiology, Glucosamine genetics, Glucosamine physiology, Glycosyltransferases genetics, Hydrogen Peroxide pharmacology, Microarray Analysis, Microbial Sensitivity Tests, Mutation, NADP metabolism, Peroxidase metabolism, Staphylococcus aureus drug effects, Staphylococcus aureus genetics, Staphylococcus aureus growth & development, Xanthophylls biosynthesis, Bacterial Proteins physiology, Cysteine analogs & derivatives, Glucosamine analogs & derivatives, Oxidative Stress physiology, Staphylococcus aureus metabolism
- Abstract
In Staphylococcus aureus, the low-molecular-weight thiol called bacillithiol (BSH), together with cognate S-transferases, is believed to be the counterpart to the glutathione system of other organisms. To explore the physiological role of BSH in S. aureus, we constructed mutants with the deletion of bshA (sa1291), which encodes the glycosyltransferase that catalyzes the first step of BSH biosynthesis, and fosB (sa2124), which encodes a BSH-S-transferase that confers fosfomycin resistance, in several S. aureus strains, including clinical isolates. Mutation of fosB or bshA caused a 16- to 60-fold reduction in fosfomycin resistance in these S. aureus strains. High-pressure liquid chromatography analysis, which quantified thiol extracts, revealed some variability in the amounts of BSH present across S. aureus strains. Deletion of fosB led to a decrease in BSH levels. The fosB and bshA mutants of strain COL and a USA300 isolate, upon further characterization, were found to be sensitive to H2O2 and exhibited decreased NADPH levels compared with those in the isogenic parents. Microarray analyses of COL and the isogenic bshA mutant revealed increased expression of genes involved in staphyloxanthin synthesis in the bshA mutant relative to that in COL under thiol stress conditions. However, the bshA mutant of COL demonstrated decreased survival compared to that of the parent in human whole-blood survival assays; likewise, the naturally BSH-deficient strain SH1000 survived less well than its BSH-producing isogenic counterpart. Thus, the survival of S. aureus under oxidative stress is facilitated by BSH, possibly via a FosB-mediated mechanism, independently of its capability to produce staphyloxanthin.
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- 2014
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49. Biophysical features of bacillithiol, the glutathione surrogate of Bacillus subtilis and other firmicutes.
- Author
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Sharma SV, Arbach M, Roberts AA, Macdonald CJ, Groom M, and Hamilton CJ
- Subjects
- Amines chemistry, Bacillus subtilis metabolism, Carboxylic Acids chemistry, Cysteine chemistry, Glucosamine chemistry, Glutathione chemistry, Kinetics, Oxidation-Reduction, Sulfhydryl Compounds chemistry, Bacillus subtilis chemistry, Cysteine analogs & derivatives, Glucosamine analogs & derivatives
- Abstract
Bacillithiol (BSH) is the major low-molecular-weight (LMW) thiol in many low-G+C Gram-positive bacteria (Firmicutes). Evidence now emerging suggests that BSH functions as an important LMW thiol in redox regulation and xenobiotic detoxification, analogous to what is already known for glutathione and mycothiol in other microorganisms. The biophysical properties and cellular concentrations of such LMW thiols are important determinants of their biochemical efficiency both as biochemical nucleophiles and as redox buffers. Here, BSH has been characterised and compared with other LMW thiols in terms of its thiol pKa , redox potential and thiol-disulfide exchange reactivity. Both the thiol pKa and the standard thiol redox potential of BSH are shown to be significantly lower than those of glutathione whereas the reactivities of the two compounds in thiol-disulfide reactions are comparable. The cellular concentration of BSH in Bacillus subtilis varied over different growth phases and reached up to 5 mM, which is significantly greater than previously observed from single measurements taken during mid-exponential growth. These results demonstrate that the biophysical characteristics of BSH are distinctively different from those of GSH and that its cellular concentrations can reach levels much higher than previously reported., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2013
- Full Text
- View/download PDF
50. 85.7 MHz repetition rate mode-locked semiconductor disk laser: fundamental and soliton bound states.
- Author
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Butkus M, Viktorov EA, Erneux T, Hamilton CJ, Maker G, Malcolm GP, and Rafailov EU
- Abstract
Mode-locked optically pumped semiconductor disk lasers (SDLs) are in strong demand for applications in bio-medical photonics, chemistry, space communications and non-linear optics. However, the wider spread of SDLs was constrained as they are operated in high repetition rates above 200 MHz due to short carrier lifetimes in the semiconductors. Here we demonstrate experimentally and theoretically that it is possible to overcome the limitation of fast carrier relaxation and show significant reduction of repetition rate down to 85.7 MHz by exploiting phase-amplitude coupling effect. In addition, a low repetition rate SDL serves as a test-bed for bound soliton state previously unknown for semiconductor devices. The breakthrough to sub-100 MHz repetition rate will open a whole new window of development opportunities.
- Published
- 2013
- Full Text
- View/download PDF
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