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Biomedical subjects

S Bailey

Publications and source records attributed to S Bailey.

At least 73 records · Page 4Linked to original sources
PubMed2000

Hybrid-cluster protein (HCP) from Desulfovibrio vulgaris (Hildenborough) at 1.6 A resolution.

The three-dimensional structure of the hybrid cluster protein from Desulfovibrio vulgaris (Hildenborough) has been determined at 1.6 A resolution using synchrotron X-ray radiation. The protein can be divided into three domains: an N-terminal mainly alpha-helical domain and two similar domains comprising a central beta-sheet flanked by alpha-helices. The protein contains two 4Fe clusters with an edge-to-edge distance of 10.9 A. Four cysteine residues at the N-terminus of the protein are ligands to the iron atoms of a conventional [4Fe-4S] cubane cluster. The second cluster has an unusual asymmetric structure and has been named the hybrid cluster to reflect the variety of protein ligands, namely two mu-sulfido bridges, two mu(2)-oxo bridges, and a further disordered bridging ligand. Anomalous differences in data collected at 1.488 A and close to the iron edge at 1.743 A have been used to confirm the identity of the metal and sulfur atoms. The hybrid cluster is buried in the center of the protein, but is accessible through a large hydrophobic cavity that runs the length of domain 3. Hydrophobic channels have previously been identified as access routes to the active centers in redox enzymes with gaseous substrates. The hybrid cluster is also accessible by a hydrophilic channel. The [4Fe-4S] cubane cluster is close to an indentation on the surface of the protein and can also be approached on the opposite side by a long solvent channel. At the present time, neither the significance of these channels nor, indeed, the function of the hybrid cluster protein is known.

Amino Acid Sequence↗
PubMed2000

The United Kingdom Children's Cancer Study Group's second germ cell tumor study: carboplatin, etoposide, and bleomycin are effective treatment for children with malignant extracranial germ cell tumors, with acceptable toxicity.

PURPOSE: To evaluate carboplatin, etoposide, and bleomycin (JEB) in children with malignant extracranial germ cell tumors (GCTs). PATIENTS AND METHODS: Malignant GCTs in children aged 0 to 16 years were excised without major morbidity or otherwise biopsied. Stage I testicular and some ovarian GCTs were resected and monitored with alpha-fetoprotein (AFP) ("watch-and-wait" approach). Patients with recurrent stage I disease and all other patients received JEB (etoposide 120 mg/m(2) on days 1 through 3, carboplatin 600 mg/m(2) on day 2, and bleomycin 15 mg/m(2) on day 3). Courses were administered every 3 to 4 weeks until remission, and then two more courses were given. Chemotherapy toxicities were assessed using World Health Organization or Brock grading. RESULTS: Between January 1989 and December 1997, 192 patients were registered. Eight were excluded because either there was no histologic diagnosis (n = 3) or chemotherapy was given off-study (n = 5). The remaining 184 patients had germinoma (n = 20), malignant teratoma (n = 55), embryonal carcinoma (n = 1), yolk sac tumor (n = 107), or choriocarcinoma (n = 1). Forty-seven patients were treated with surgery alone, and 137 patients received JEB. The 5-year survival rate in March 1999 for all 184 patients was 93.2% (95% confidence interval [CI], 87.9% to 96.3%); for the 137 JEB-treated patients, it was 90.9% (95% CI, 83.9% to 95.0%), with an event-free survival rate of 87.8% (95% CI, 81.1% to 92.4%). The median follow-up after JEB treatment was 53 months (range, 0 to 109 months); the median number of courses was five (range, three to eight). Site, stage, and AFP level had prognostic significance. Nonfatal hematologic toxicity was common, but deafness and pulmonary and renal toxicities were rare. One child died of a thoracic tumor and bronchopulmonary dysplasia, and another died of acute myeloid leukemia. CONCLUSION: Conservative surgery, a watch-and-wait approach after complete excision, and JEB for those requiring chemotherapy produced high cure rates and few serious complications.

Adolescent↗
PubMed2000

Measurement of J/psi and psi(2S) polarization in pp collisions at sqrt[s] = 1.8 TeV.

We have measured the polarization of J/psi and psi(2S) mesons produced in pp collisions at sqrt[s] = 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992-1995. The polarization of promptly produced J/psi [psi(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5]<P(T)<20 GeV/c and |y|<0.6. For P(T) greater than or approximately equal 12 GeV/c we do not observe significant polarization in the prompt component.

Journal Article↗
PubMed2000

The multiperson use of non-syringe injection equipment and risk of hepatitis c infection in a cohort of young adult injection drug users, chicago 1997-1999.

PURPOSE: The possibility that hepatitis C virus (HCV) is transmitted via the multiperson use of injection paraphernalia other than syringes has been suggested, but epidemiologic studies to examine the association are difficult to design due to saturation levels of infection in most samples of injection drug users (IDUs). This study (1) assembled a sample of young adult IDUs, among whom hepatitis C infection prevalence was still moderate, (2) measured incident HCV infection, and (3) determined the risk for seroconversion associated with specific forms of sharing injection paraphernalia.METHODS: Between 1997 and 1999, 702 IDUs, 18-30 years old, were interviewed and screened for antibodies to HCV at baseline and at 6 and 12 months post-baseline. Participants were recruited through street outreach, advertising and chain-referral from ethnically diverse neighborhoods in metropolitan Chicago. Data were analyzed using standard survival statistical methods.RESULTS: HCV prevalence was 27% at enrollment. During 296.5 person-years of observation, we observed 37 HCV seroconversions (incidence: 12.5/100 person-years). The adjusted relative hazard (RH) of seroconversion, after controlling for demographic and drug use covariates, was highest for sharing cookers (RH, 3.58; 95% CI 1.47-8.70), followed by sharing rinse water (RH, 2.16; 95% CI 1.03-4.52), and cottons (RH, 1.84; 95% CI 0.95-3.56). Risk associated with syringe sharing was marginally significant, and backloading was unassociated with hepatitis C seroconversion. Adjusting for syringe sharing, the independent effects of sharing cookers and cottons remained significant, and a final model that included each sharing practice demonstrated that sharing cookers had at the strongest association with seroconversion (RH, 3.03; 95% CI 1.05-8.72).CONCLUSIONS: This study suggests that sharing non-syringe paraphernalia may be an important cause of hepatitis C virus transmission between IDUs.

Journal Article↗
PubMed2000

Reversible dissociation of thiolate ligands from molybdenum in an enzyme of the dimethyl sulfoxide reductase family.

Much is unknown concerning the role of thiolate ligands of molybdenum in molybdopterin enzymes. It has been suggested that thiolate dissociation from molybdenum is part of the catalytic mechanism of bis-molybdopterin enzymes of the dimethyl sulfoxide reductase (DMSOR) family. For DMSOR from Rhodobacter capsulatus, thiolate dissociation has therefore been investigated crystallographically, by UV/visible spectroscopy, and by enzyme assays. When crystallized from sodium citrate, all four thiolates of DMSOR are within bonding distance of Mo, but after extended exposure to Na(+)-Hepes, a pair of thiolates dissociates, a mixture of structures being indicated after shorter exposures to this buffer. DMSOR is stable in sodium citrate and other buffers but unstable aerobically although not anaerobically in Na(+)-Hepes. Aerobically in Na(+)-Hepes, a first-order reaction (k = 0.032 hr(-)(1) at 37 degrees C) leads to loss of activity in the backward but not the forward (dimethyl sulfoxide reduction) assay and loss of absorption at lambda > approximately 450 nm. This reaction can be reversed by a cycle of reduction and reoxidation ("redox-cycling"). Slower irreversible loss of activity in the forward assay and cofactor dissociation follow. Spectral analogy with a mono-molybdopterin enzyme supports the conclusion that in the Hepes-modified DMSOR form, only two cofactor dithiolene sulfur atoms are coordinated to molybdenum. Loss of activity provides the first clear evidence that sulfur ligand dissociation is an artifact, not part of the catalytic cycle. Clearly, structural data on DMSOR samples extensively exposed to Hepes is not directly relevant to the native enzyme. The nature of the oxygen ligands detected crystallographically is discussed, as is the specificity of Hepes and the mechanism whereby its effects are achieved. DMSOR forms complexes with Na(+)-Hepes and other buffer ions. For DMSOR crystallized from Hepes, electron density in the substrate binding channel suggests that buffers bind in this site. Like the as-prepared enzyme, the modified form (DMSOR(mod)D), known to arise on extended aerobic exposure to dimethyl sulfide, is susceptible to a further degradative reaction, although this is not buffer-dependent. It involves loss of absorption at lambda > approximately 450 nm and, presumably, dissociation of thiolate ligands. Evidence is presented that, as a result of O(2) damage, DMSOR samples not submitted to redox-cycling may be contaminated with DMSOR(mod)D and with material absorbing in the region of 400 nm, analogous to the Hepes-modified enzyme. Since the latter lacks absorption at lambda > approximately 450 nm, its presence may escape detection.

Buffers↗
PubMed2000

Involvement of an FtsH homologue in the assembly of functional photosystem I in the cyanobacterium Synechocystis sp. PCC 6803.

The Synechocystis sp. PCC 6803 genome encodes four putative homologues of the AAA protease FtsH, two of which (slr0228 and sll1463) have been subjected to insertional mutagenesis in this study. Disruption of sll1463 had no discernible effect but disruption of slr0228 caused a 60% reduction in the abundance of functional photosystem I, without affecting the cellular content of photosystem II or phycobilisomes. Fluorescence and immunoblotting analyses show reductions in PS I polypeptides and possible structural alterations in the residual PS I, indicating an important role for slr0228 in PS I biogenesis.

ATP-Dependent Proteases↗
PubMed2000

Search for scalar top and scalar bottom quarks in pp collisions at square root s=1.8 TeV.

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb-1 of pp collisions at sqrt[s]=1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.

Journal Article↗
PubMed2000

Dimethylsulfoxide reductase: an enzyme capable of catalysis with either molybdenum or tungsten at the active site.

DMSO reductase (DMSOR) from Rhodobacter capsulatus, well-characterised as a molybdoenzyme, will bind tungsten. Protein crystallography has shown that tungsten in W-DMSOR is ligated by the dithiolene group of the two pyranopterins, the oxygen atom of Ser147 plus another oxygen atom, and is located in a very similar site to that of molybdenum in Mo-DMSOR. These conclusions are consistent with W L(III)-edge X-ray absorption, EPR and UV/visible spectroscopic data. W-DMSOR is significantly more active than Mo-DMSOR in catalysing the reduction of DMSO but, in contrast to the latter, shows no significant ability to catalyse the oxidation of DMS.

Binding Sites↗
PubMed2000

A newly created splice donor site in exon 25 of the MyBP-C gene is responsible for inherited hypertrophic cardiomyopathy with incomplete disease penetrance.

BACKGROUND: Hypertrophic cardiomyopathy is a myocardial disorder resulting from inherited sarcomeric dysfunction. We report a mutation in the myosin-binding protein-C (MyBP-C) gene, its clinical consequences in a large family, and myocardial tissue findings that may provide insight into the mechanism of disease. METHODS AND RESULTS: History and clinical status (examination, ECG, and echocardiography) were assessed in 49 members of a multigeneration family. Linkage analysis implicated the MyBP-C gene on chromosome 11. Myocardial mRNA, genomic MyBP-C DNA, and the myocardial proteins of patients and healthy relatives were analyzed. A single guanine nucleotide insertion in exon 25 of the MyBP-C gene resulted in the loss of 40 bases in abnormally processed mRNA. A 30-kDa truncation at the C-terminus of the protein was predicted, but a polypeptide of the expected size ( approximately 95 kDa) was not detected by immunoblot testing. The disease phenotype in this family was characterized in detail: only 10 of 27 gene carriers fulfilled diagnostic criteria. Five carriers showed borderline hypertrophic cardiomyopathy, and 12 carriers were asymptomatic, with normal ECG and echocardiograms. The age of onset in symptomatic patients was late (29 to 68 years). In 2 patients, outflow obstruction required surgery. Two family members experienced premature sudden cardiac death, but survival at 50 years was 95%. CONCLUSIONS: Penetrance of this mutation was incomplete and age-dependent. The large number of asymptomatic carriers and the good prognosis support the interpretation of benign disease.

Adult↗
PubMed2000

Global experience in cervical carotid artery stent placement.

The purpose of this article is to review and update the current status of carotid artery stent placement in the world. Surveys to major interventional centers in Europe, North and South America, and Asia were initially completed in June 1997. Subsequent information from these 24 centers in addition to 12 new centers has been obtained to update the information. The survey asked the various questions regarding the patients enrolled, procedure techniques, and results of carotid stenting, including complications and restenosis. The total number of endovascular carotid stent procedures that have been performed worldwide to date included 5,210 procedures involving 4,757 patients. There was a technical success of 98.4% with 5,129 carotid arteries treated. Complications that occurred during the carotid stent placement or within a 30-day period following placement were recorded. Overall, there were 134 transient ischemic attacks (TIAs) for a rate of 2.82%. Based on the total patient population, there were 129 minor strokes with a rate of occurrence of 2.72%. The total number of major strokes was 71 for a rate of 1.49%. There were 41 deaths within a 30-day postprocedure period resulting in a mortality rate of 0.86%. The combined minor and major strokes and procedure-related death rate was 5.07%. Restenosis rates of carotid stenting have been 1.99% and 3.46% at 6 and 12 months, respectively. The rate of neurologic events after stent placement has been 1.42% at 6-12-month follow-up. Endovascular stent treatment of carotid artery atherosclerotic disease is growing as an alternative for vascular surgery, especially for patients that are high risk for standard carotid endarterectomy. The periprocedure risks for major and minor strokes and death are generally acceptable at this early stage of development and have not changed significantly since the first survey results. Cathet. Cardiovasc. Intervent. 50:160-167, 2000.

Carotid Stenosis↗
PubMed2000

Collecting and using aboriginal health information in New South Wales.

OBJECTIVE: To describe the development of guidelines for the management of Aboriginal health information in NSW. The purpose of the guidelines is to promote the ethical management of Aboriginal health information, with appropriate consideration for cultural factors. METHODS: The guidelines were developed collaboratively by the NSW Aboriginal Health Partnership, which comprises NSW Health (the central administrative office, named NSW Department of Health, and the Area Health Services) and the NSW Aboriginal Health and Medical Research Council (AHMRC), the peak body representing member Aboriginal Community Controlled Health Services in NSW. A lengthy and comprehensive consultation process enabled a wide range of interested groups to have input into the guidelines. RESULTS: The project culminated in the production of the NSW Aboriginal Health Information Guidelines, covering the collection, ownership, storage, security, release, usage, interpretation and reporting of information, as well as issues of privacy and confidentiality. The Guidelines formed the basis of a formal Memorandum of Understanding, signed by the NSW Minister for Health, NSW Department of Health and the AHMRC, on 24 August 1998. CONCLUSIONS AND IMPLICATIONS: The Guidelines make an important contribution to meeting a need for protocols on the collection, ownership and use of Aboriginal health information. Their production reflects successful collaboration between government and Aboriginal Community Controlled Health Services in NSW. Future reviews of the Guidelines will ensure their effectiveness and consistency with Aboriginal community principles.

Guidelines as Topic↗
PubMed2000

Relationship between psychotic disorders in adolescence and criminally violent behaviour. A retrospective examination.

BACKGROUND: The interaction between psychosis and violence in adults is an important area of research receiving attention. To date there is little available data examining this relationship in adolescence. AIMS: To investigate the possible relationships between criminally violent types of behaviour, and psychopathology and social factors, among adolescents suffering from a psychotic disorder. METHOD: A retrospective case note study of 39 in-patients diagnosed as having a psychotic disorder and admitted to one of two adolescent psychiatry units (one secure, one open). Cases were divided into a 'violent' and a 'non-violent' group, and these two groups were then compared for social and psychopathological variables. RESULTS: There was no association between recorded psychopathology and criminally violent behaviour. Criminally violent behaviour was associated with a history of emotional or physical abuse, contact with social or mental health services, and previous criminal behaviour. CONCLUSIONS: These findings fail to echo results of studies in adult schizophrenia; they suggest that violent behaviour in psychosis is associated more closely with social factors than with specific symptoms of the psychotic illness. Potential explanations are discussed.

Adolescent↗
PubMed2000

Families, groups and clusters of local and health authorities: revised for authorities in 1999.

This is the second of two articles describing the revision of The ONS classification of local and health authorities of Great Britain to take account of area changes in the 1990's. It presents local authorities in Great Britain as at April 1999 in terms of Families, Groups and Clusters, based on 37 socio-economic and demographic variables from the 1991 Census. Health authorities are presented in terms of Families and Groups only, based on the same variables. The previous article (in Population Trends 98) presented, for each local and health authority, up to four other authorities to which it is 'most similar'.

Adolescent↗
PubMed2000

Local Drug Delivery During Percutaneous Coronary Intervention.

Local delivery of therapeutic agents offers promise as adjuncts during percutaneous interventions. The potential advantages of local delivery include direct delivery to the lesion site, lower doses of the agent resulting in lower costs and/or greater efficiency, and the potential for increased potency. Early trials focused primarily on the use of anti-thrombotic therapy using agents such as urokinase, heparin, and the heparinoids. These therapies, limited by an inadequate knowledge of the pharmacodynamics of the agents, had disappointing outcomes. Recent trials have focused on the use of later generation delivery devices that have improved delivery kinetics as well as agents that have improved resonance within the artery wall. It is anticipated that these new approaches will improve the clinical outcomes of local drug delivery during percutaneous interventions.

Journal Article↗
PubMed2000

The efficacy of acarbose in type 2 diabetes mellitus in Jamaica.

The efficacy and tolerability of acarbose was studied in type 2 diabetic patients eating a typical Jamaican diet. The study was an open label parallel group study without placebo control. Of the 51 subjects recruited, five (9.8%) did not complete the study and were excluded from further analysis. Six (13%) of the remaining 46 had adverse side effects and did not complete the protocol. Of the remaining 40 (Gp A), acarbose was added to their previous regime of diet alone (n = 15), [Gp B], oral hypoglycaemic agents, OHAs (n = 17), [Gp C], or insulin (n = 8), Gp D]. In addition, during the run-in period all subjects had one session each with a dietitian and a diabetes educator. Over a 3-month period, significant reductions in average glucose (mmol) were observed in Gp B 10.5 +/- 1.1 to 8.4 +/- 0.9 (p < 0.027) and, from 11.0 +/- 1.0 to 8.7 +/- 0.7 (p < 0.01) in Gp C. Similarly, total glycosylated haemoglobin fell from 14.8 +/- 1.1% to 12.2 +/- 1.0% (p < 0.016) in Gp B, from 14.9 +/- 1.1 to 11.9 +/- 1.1% (p < 0.002) in Gp C, and from 14.1 +/- 1.4 to 11.8 +/- 1.4 (p < 0.02) in Gp D. Twenty-three per cent (23%) of the patients experienced flatulence; 7.5%, changes in bowel habits and 5%, abdominal cramps and discomfort. Acarbose is effective as monotherapy and as combination therapy with oral hypoglycaemic agents or insulin. Side effects were common, but tolerable.

Acarbose↗