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Biomedical subjects

S Jones

Publications and source records attributed to S Jones.

At least 325 records · Page 18Linked to original sources
PubMed1996

Interferon-gamma as a regulator of squamous differentiation.

Interferon-gamma (IFN-gamma) is a potent immunomodulatory molecule. Recent studies demonstrate that IFN-gamma can induce growth arrest and differentiation in epithelial cells. The signalling pathways controlling growth and differentiation in epithelial cells appears to be different to those regulating immune functions in non-epithelial cells and appear to impact on key cell cycle regulatory genes such as cdk1 and E2F1. In addition, studies with IFN-gamma have highlighted the complexity of the signalling pathways regulating the expression of differentiation markers in squamous differentiating epithelia. Given the actions of IFN-gamma upon epithelial cell growth and differentiation it should be considered a potential regulator of both immune and epithelial cell targets in various inflammatory pathologies such as psoriasis.

Adjuvants, Immunologic↗
PubMed1996

Carbamylated hemoglobin: a potential marker for the adequacy of hemodialysis therapy in end-stage renal failure.

Urea can dissociate in vivo to form isocyanic acid which can react with hemoglobin to form carbamylated hemoglobin. Previous work has shown that formation of carbamylated hemoglobin depends upon both the severity and the duration of renal failure. To determine whether carbamylated hemoglobin can be used as an assessment of the adequacy of hemodialysis treatment, we prospectively studied 55 stable patients who regularly attended our hospital dialysis program. Carbamylated hemoglobin was greater in those patients with a Kt/V of < or = 1.1 compared to those with a Kt/V of > 1.1 (120 +/- 8 micrograms VH/gHb versus 99 +/- 7, P < 0.01), and there was a negative correlation with Kt/V (r = -0.37, P = 0.007). There were positive correlations between carbamylated hemoglobin and the time-averaged urea concentration (r = 0.4, P = 0.004), and a negative correlation with the urea reduction ratio (r = -0.37, P = 0.01). Carbamylated hemoglobin may therefore be a useful marker of the degree of uremia, just as glycosylated hemoglobin is used in the assessment of patients with diabetes mellitus.

Adolescent↗
PubMed1996

Conversion of an extracellular cytolysin into a phagosome-specific lysin which supports the growth of an intracellular pathogen.

Listeria monocytogenes is a facultative intracellular pathogen which secretes a pore-forming cytolysin, listeriolysin O (LLO), necessary for intracellular growth. Clostridium perfringens is an extracellular pathogen which secretes a related cytolysin, perfringolysin O (PFO). When PFO is secreted by intracellular L. monocytogenes, it is toxic to the infected host cell. PFO-mediated toxicity renders the infected host cell permeable to gentamicin and leads to the death of the intracellular bacteria. In this study, we selected for L. monocytogenes mutants in which PFO supported the intracellular growth of L. monocytogenes. Six independent mutants were isolated, each containing a single amino acid change within the PFO protein. Three classes of PFO mutations were identified, all capable of mediating lysis of the vacuole but without a toxic effect upon the infected host cell. The first class had a severe defect in haemolytic activity. The second class had a change in the pH optimum of PFO. The third class had nearly wild-type levels of haemolytic activity, but had a decrease in protein half-life in the host-cell cytosol. Acquisition of single amino acid changes in PFO were sufficient to convert an extracellular cytolysin into a vacuole-specific lysin which mediated growth of L. monocytogenes in cultured cells.

Bacterial Proteins↗
PubMed1996

Bartonella (Rochalimaea) quintana causing fever and bacteremia in an immunocompromised patient with non-Hodgkin's lymphoma.

A 48-yr-old man with stage IV non-Hodgkin's lymphoma, became neutropenic following chemotherapy and developed a fever. His blood cultures were processed to enhance the yield of fastidious bacteria. A slow-growing, capnophilic Gram-negative rod was isolated. The febrile episode was treated with cefotaxime, imipenem and vancomycin and resolved. The bacterial isolate was identified as Bartonella (Rochalimaea) quintana by 16S-rDNA gene sequencing. The isolate showed 99.8% sequence homology with the type strain. This is the first isolation of Bartonella (Rochalimaea) quintana from a bacteremic patient in Australia. This bacterium is a fastidious Gram-negative rod requiring prolonged culture for its isolation. Patients with culture-negative pyrexia, especially immunocompromised patients, may need to be investigated for infection with this agent.

Bacteremia↗
PubMed1996

Cerebellar mutism following posterior fossa tumour surgery.

Two cases of transient mutism following operative removal of cerebellar medulloblastoma are reported. These add to the few cases reported in the literature of this rare complication of posterior fossa tumour surgery in children.

Articulation Disorders↗
PubMed1996

DNA sequence analysis of methylene chloride-induced HPRT mutations in Chinese hamster ovary cells: comparison with the mutation spectrum obtained for 1,2-dibromoethane and formaldehyde.

Glutathione-S-transferase-mediated metabolism of methylene chloride (MC) generates S-chloromethylglutathione, which has the potential to react with DNA, and formaldehyde, which is a known mutagen. MC-induced mutations in the HPRT gene of Chinese hamster ovary cells have been sequenced and compared with the mutations induced by 1, 2-dibromoethane (1,2-DEB), which is known to act through a glutathione conjugate, and formaldehyde. All three compounds induced primarily point mutations, with a small number of insertion and deletion events. The most common point mutations induced by MC were GC-->AT transitions (4/8), with two GC-->CG transversions and two AT-->TA transversions. This pattern of mutations showed greater similarity with 1,2-DBE, where the dominant point mutations were GC-->AT transitions (7/9), than formaldehyde, where all mutations were single base transversions and 5/6 occurred from AT base pairs. The mutation sequence results for MC suggest that S-chloromethylglutathione plays a major role in MC mutagenesis, with only a limited contribution from formaldehyde. The involvement of a glutathione (GSH) conjugate in MC mutagenicity would be analogous to the well-characterized pathway of activation of 1,2-DBE.

Animals↗
PubMed1996

Effect of Eleutherococcus senticosus on submaximal and maximal exercise performance.

We investigated the effect of Eleutherococcus senticosus Maxim L (ESML) on performance during submaximal and maximal aerobic exercise. Twenty highly trained distance runners randomly assigned in matched pairs to either an experimental (ESML) or placebo (PL) group, participated in an 8-wk double-blind study during which they completed five trails of a 10-min treadmill run at their 10 km (10K) race pace and a maximal treadmill test (T(max)). Following a baseline trail, ESML and PL consumed, respectively, 3.4 ml of ESML extract or placebo daily for 6 wk. Subjects were tested every 2 wk during supplementation and 2 wk following withdrawal. Heart rate (HR), oxygen consumption (VO2), expired minute volume (VE), ventilatory equivalent for oxygen (VE/VO2), respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were measured during the 10K and T(max) tests. Resting, post-10K and post-T(max) blood samples were analyzed for serum lactate. No significant differences were observed between ESML and PL for: HR, VO2, VE, VE/VO2, RER, or RPE; T(max) time to exhaustion; or serum lactate. The data do not support an ergogenic effect of ESML supplementation on selected metabolic, performance, or psychologic parameters associated with submaximal and maximal aerobic exercise tasks.

Adult↗
PubMed1996

An action research investigation into the feasibility of experienced registered sick children's nurses (RSCNs) becoming children's emergency nurse practitioners (ENPs).

Emergency nurse practitioners (ENPs) formally developed in accident and emergency (A & E) departments as a direct response to waiting times for the walking wounded, the need to reduce junior doctor hours and changes in nursing practice. ENPs existed informally for many years in minor injuries units and specialist ophthalmic departments. This study aimed to examine whether or not the role of ENP could be applied to the specialist service of a paediatric casualty department. The results showed that 3% of patients could be seen and treated to conclusion by a children's ENP, and some patients could have their care accelerated by a children's ENP. The introduction of children's ENPs would have an impact on waiting times, junior doctors work-load and the quality of patient care.

Emergency Nursing↗
PubMed1996

Attitudes of patients to medical student participation: general practice consultations on the Cambridge Community-Based Clinical Course.

The clinical medical students on the Cambridge Community-Based Clinical Course (CCBCC) derive part of their training by taking part in consultations between patients and their general practitioners. Patients' attitudes to this arrangement and their support for student training in a general practice setting are an important factor in the development of community-based education. A postal questionnaire seeking information from patients achieved an 84% response rate. Both the numerical results and the patients' comments are presented. Patients proved generally supportive of the community-based course and some identified positive benefits to themselves from this provision. The large majority of patients did not mind the presence of medical students during consultations, although there are some areas in which patients are less willing to involve students.

Attitude↗
PubMed1996

Shiftwork and mortality from ischaemic heart disease.

OBJECTIVES: To investigate the relation between shift work and death from ischaemic heart disease (IHD). METHODS: A nested case-control approach was used. The cohort comprised male manual workers who joined an industrial company aged 50 years or under between 1 January 1950 and 31 December 1992 and worked there for at least one month. Cases were 467 cohort members who died during the same period aged 75 years or under, with ischaemic heart disease (IHD) (international classification of diseases (ICD) 410-414) coded from the death certificate. For each case a control worker was chosen, who joined the company at the same age and in the same period but who survived the case. Work status (shift work or day work) was assigned to cases for their entire employment and to controls for that part of their employment which preceded the matching case's death. The main source of information was historical personnel records containing pay codes which differed for day work and shift work. Information on weight, height, blood pressure, and smoking from a pre-employment medical was available. RESULTS: Two thirds of subjects had been employed for at least one month as shift workers and there was evidence that they had slightly better health at recruitment than day workers. The odds ratio for shift workers during the period starting 10 years after shift work began, and after adjustment for height, body mass index, blood pressure, smoking, duration of employment, and job status (skilled or unskilled) was 0.90 (90% confidence interval (90% CI): 0.68-1.21). There was no relation between risk of IHD death, and duration of shift work, but there was evidence of a reduced risk when actively employed as a shift worker, together with an increased risk in the first five years after leaving shift work to do day work. CONCLUSIONS: Shift work did not increase the risk of death from ischaemic heart disease in this study. Those workers with poorer cardiovascular health may be under represented in groups with longer shift work experience because of health related selection out of shift work.

Adult↗
PubMed1996

Glycine minimizes reperfusion injury in a low-flow, reflow liver perfusion model in the rat.

This study investigated the effects of glycine on reperfusion injury in a low-flow, reflow liver perfusion model. With this protocol, livers were perfused at low flow rates of approximately 1 ml.g-1. min-1 for 75 min, which caused cells in pericentral regions of the liver lobule to become anoxic because of insufficient delivery of oxygen. When normal flow rates (approximately 4 ml.g-1.min-1) were restored for 40 min, an oxygen-dependent reperfusion injury occurred. Upon reflow, lactate dehydrogenase (LDH), a cytosolic enzyme, and malondialdehyde (MDA), an end product of lipid peroxidation, were released into the effluent perfusate. LDH increased from basal levels of approximately 1-35 IU.g-1.h-1 in livers from control rats. Glycine (0.06-2.00 mM) minimized enzyme release in a dose-dependent manner (half-maximal decrease = 133 microM), with maximal values only reaching 5 IU.g-1.h-1 when glycine was increased to 2 mM. Reflow for 40 min after 75 min of low-flow hypoxia caused death in approximately 30% of previously anoxic parenchymal cells in pericentral regions; however, infusion of glycine (2 mM) decreased cell death to less than 10%. Strychnine (1 mM), which was found to mimic the cytoprotective effect of glycine in proximal renal tubules, also reduced LDH release to 11 IU.g-1.h-1 in this study. Bile was released at rates of approximately 42 microliters.g-1.h-1 in livers from control rats, but values were not altered significantly by glycine. Maximal MDA production during reperfusion decreased by 35% with 0.6 mM of glycine. Trypan blue distribution time, an indicator of hepatic microcirculation, was reduced significantly by glycine at 5 and 40 min after reflow, but changes were about twofold greater at later time points compared with earlier ones (half-maximal decrease = 225 microM). Time for oxygen to reach steady state upon reflow was reduced by glycine in a dose-dependent manner, and the rates of entry and exit of a dye confined to vascular space (fluorescein dextran) were increased two- to threefold by glycine, respectively. Taken together, these data indicate that a reperfusion injury that occurs in previously hypoxic pericentral regions of the liver upon reintroduction of oxygen is minimized by glycine, possibly by action on a glycine-sensitive anion channel to improve microcirculation during the reperfusion period.

Animals↗
PubMed1996

Dual immunodetection and hybridisation in situ of opsin mRNA and rhodopsin protein in retinal sections.

We describe a simple method for combining in situ hybridisation and immunohistochemistry on the same retinal section. The technique was developed using a radiolabelled cDNA probe for opsin and an antibody (ROS1F4) against rhodopsin. This method retains the antigenic sites if immunocytochemistry is performed prior to in situ hybridisation. Opsin mRNA was found in the photoreceptor inner segment with rhodopsin immunolocalised to the photoreceptor outer segments. The technique should be applicable to numerous situations including analysis of the sequence of events in the expression and synthesis of the various opsins during retinal development and degeneration.

Antibodies, Monoclonal↗
PubMed1996

Mucus entrapment of particles by a suspension-feeding tilapia (Pisces: Cichlidae)

A miniature fiberoptic endoscope was used to observe the processes of particle encounter and retention inside the buccopharyngeal cavity of suspension-feeding tilapia. Small particles (38 &micro;m to 1.0 mm in diameter) were trapped in strands and aggregates of mucus, which usually slid posteriorly on the ceratobranchials of arches I&shy;IV towards the esophagus while the fish pumped water through the buccopharyngeal cavity. During stage 1 of periodic reversals of water flow inside the buccopharynx, mucus-bound particles usually lifted off the arch surfaces and travelled a short distance in an anterior or anterodorsal direction. During stage 2 of a reversal, the mucus usually resumed travel in a posterior or posteroventral direction and exited the field of view. Mucus was present less often during feeding on large particles (3&shy;10 mm in diameter) than on small particles, and large particles were rarely observed to be attached to mucus. We discuss the advantages to suspension-feeding fishes of using aerosol filtration by mucus entrapment rather than sieving, and predict that many cichlid and cyprinid suspension feeders that consume bacteria and phytoplankton use mucus for aerosol filtration.

Journal Article↗
PubMed1996

Using larvae in modern wound management.

Initial clinical experience in the UK with maggot therapy for the treatment of necrotic or infected wounds has proved very encouraging. Sterile larvae have been reared in the Surgical Materials Testing Laboratory for this purpose. This paper reports the use of larvae in six patients and discusses some of the advantages and disadvantages of this form of therapy.

Adult↗