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Biomedical subjects

S Thomas

Publications and source records attributed to S Thomas.

At least 181 records · Page 10Linked to original sources
PubMed2000

Effect of topiramate on body weight and body composition of osborne-mendel rats fed a high-fat diet: alterations in hormones, neuropeptide, and uncoupling-protein mRNAs.

The effects of topiramate on food intake and body composition were investigated in rats fed a high-fat diet and compared with rats that were pair fed or treated with D-fenfluramine. Topiramate (40 mg. kg. d for 80 d) reduced body-weight gain in a manner similar to that of pair-fed rats and D-fenfluramine-treated rats. The reduction in body fat accounted for all the weight reduction after topiramate treatment but not after pair feeding or D-fenfluramine treatment. Topiramate reduced food intake acutely and increased metabolic rate. There were also significant reductions in leptin, insulin, and corticosterone. In the hypothalamus, topiramate increased mRNA for neuropeptide Y, reduced mRNA for neuropeptide-Y Y1 and Y5 receptors, corticotropin-releasing hormone (CRH), and type II glucocorticoid receptors but had no effect on mRNA levels for the short or long form of the leptin receptor. In peripheral tissues, topiramate reduced leptin mRNA in adipose tissue, had no effect on uncoupling protein 1 mRNA in brown adipose tissue but had tissue-selective effects on uncoupling proteins 2 and 3 mRNA levels in white and brown adipose tissues and muscle. In conclusion, topiramate is an effective inhibitor of weight gain in rats on a high-fat diet, but the mechanism through which the change in energy balance is achieved is unclear.

Animals↗
PubMed2000

Triage nurses' decisions using the National Triage Scale for Australian emergency departments.

The initiation of emergency care primarily depends on the decisions made by the triage nurse. Triage decisions can therefore have a profound effect on the health outcomes of patients who present for emergency care. If the National Triage Scale (NTS) was effective in providing a standardized approach to triage, a patient with a specific problem should be allocated to the same triage category, irrespective of the institution to which they present or the personnel performing the role of triage. This study examines triage nurses' level of agreement in their allocation of triage categories to patients with specific presenting problems using the NTS. Relationships between demographic characteristics of participants and triage decisions are examined and implications of any variation for triage practice and patient outcomes are explored.

Career Mobility↗
PubMed2000

Isolated orbital blowout fractures: survey and review.

The management of orbital blowout fractures is controversial. The continuing debate includes the use of antibiotics and steroids, imaging, the surgical approach, and the choice of implant material for repair of the bony defect.A cross-sectional study was undertaken to assess current practice in treating orbital blowout fractures in the UK, in the form of a tick-box questionnaire. The questionnaire contained 9 closed and 2 open questions, and was forwarded to 256 practising fellows of the British Association of Oral and Maxillofacial Surgery. The response rate to the questionnaire was 73% (187/256). There was no consensus about the use of prophylactic antibiotics. However, 91% prescribed post-operative antibiotics and over half the respondents prescribed steroids. The most common imaging techniques used were computed tomography (CT, 88%) and plain radiograph (83%), 60% routinely sought an ophthalmic opinion and 65% assessed visual acuity. The most common surgical approaches were the subciliary (41%) and the infraorbital (37%), over half the respondents preferred to operate 6-10 days after the injury, and silicone elastomer was the preferred implant material of 66%.

Antibiotic Prophylaxis↗
PubMed2000

Cerebral metabolic response to traumatic brain injury sustained early in development: a 2-deoxy-D-glucose autoradiographic study.

Following fluid percussion (FP) traumatic brain injury (TBI), adult rats exhibit dynamic regional changes in cerebral glucose metabolism characterized by an acute (hours) increase and subsequent chronic (weeks) decrease in metabolic rates. The injury-induced hyperglycolysis is the result of ionic fluxes across cell membranes and the degree and extent of metabolic depression is predictive of neurobehavioral deficits. Given that younger animals appear to exhibit similar physiological responses to injury yet show an improved rate of recovery compared to adults, we wanted to determine if this injury-induced dynamic metabolic response to TBI is different if the injury is sustained early in life. Local cerebral metabolic rates for glucose (ICMRglc: micromol/100 g/min) using [14C]2-deoxy-D-glucose were measured immediately, 30 min, 1 day, and 3 days following a mild to moderate level of lateral FP injury in postnatal day 17 (P17) rats. Even though gross morphological damage was not evident, injured pups exhibited ipsilateral hyperglycolysis immediately after injury, predominantly in cortical regions (ranging from 59.2% to 116.5% above controls). This hyperglycolytic state subsided within 30 min, and by 1 day all cerebral structures, except the ipsilateral cerebellar cortex, showed lower rates of glucose metabolism (ranging from 5.7% to 63.0% below controls). This period of posttraumatic metabolic depression resolved within 3 days for all structures measured. Compared to previous adult studies these results suggest that the young rat pup, although exhibiting acute hyperglycolysis, is not subjected to a prolonged period of metabolic depression, which supports the findings that at this level of injury severity, these young animals show remarkable neurological sparing following TBI.

Age Factors↗
PubMed2000

Modelling photosynthesis and its control.

The dynamic and steady-state behaviour of a computer simulation of the Calvin cycle reactions of the chloroplast, including starch synthesis and degradation, and triose phosphate export have been investigated. A major difference compared with previous models is that none of the reversible reactions are assumed to be at equilibrium. The model can exhibit alternate steady states of low or high carbon assimilation flux, with hysteresis in the transitions between the steady states induced by environmental factors such as phosphate and light intensity. The enzymes which have the greatest influence on the flux have been investigated by calculation of their flux control coefficients. Different patterns of control are exhibited over the assimilation flux, the flux to starch and the flux to cytosolic triose phosphate. The assimilation flux is mostly sensitive to sedoheptulose bisphosphatase and Rubisco, with the exact distribution depending on their relative activities. Other enzymes, particularly the triose phosphate translocator, become more influential when other fluxes are considered. These results are shown to be broadly consistent with observations on transgenic plants.

Computer Simulation↗
PubMed2000

Effects of pH and trace minerals on long-term starvation of Leuconostoc mesenteroides.

Laboratory experiments have definitively shown that exopolymer-producing bacteria have the potential to modify the flow of fluids in oil reservoirs to enhance oil production. Once injected into the reservoir, they will be subjected to a wide range of pH values and to starvation resulting from nutrient depletion. For successful field implementation it is necessary to have a fundamental understanding of these effects on the viability of bacteria. This paper addresses the effects of pH and trace minerals on cell viability of Leuconostoc mesenteroides during carbon source depletion. Two different carbon sources were used to grow cells before transferring the cells to starvation conditions: sucrose and a combination of glucose and fructose. These substrates were chosen because L. mesenteroides produces a significant amount of water-insoluble exopolymers (dextran) under sucrose-fed conditions, which may enhance cell survival under harsh conditions. The effects of dextran on the cell viability were tested at different pH values with and without trace minerals. The rate of cell death followed an exponential-decay law for different values of the solution pH. The optimal solution pH for survival was pH 5, whereas cells died rapidly at pH 3 and below and at pH 13 and above. The sucrose-fed cells showed a greater viability than cells fed glucose and fructose for all pH ranges tested. The results indicated that water-insoluble exopolymers help cells survive for longer periods of time under starvation conditions. The effects of trace minerals on cell culturability were tested at two pH values, 4.5 and 7. For both cases, cells showed a greater culturability (smaller decay rate constant) in the presence of trace minerals than without trace minerals. It was also found that the effects of trace minerals on cell culturability were greater for glucose-fructose-fed cells than for sucrose-fed cells. The Michaelis pH function theory was used for comparing the relationships between the cell decay rate and pH.

Biofilms↗
PubMed2000

Regional variation in incidence and case fatality of myocardial infarction among young women in England, Scotland and Wales.

OBJECTIVES: To examine the regional variation in incidence and case fatality of myocardial infarction among young women. DESIGN: Cross sectional survey, using population based incidence data. SETTING: England, Scotland and Wales. SUBJECTS: Subjects were women aged 16-44 with a diagnosis of myocardial infarction between 1 October 1993 and 15 October 1995. OUTCOME MEASURES: Incidence of myocardial infarction per 100,000 women years, with case fatality as a percentage of total cases. RESULTS: Incidence of myocardial infarction rose steeply from age 33 upwards, (maximum = 20.2 cases per 100,000 women years at age 44). The adjusted incidence rate for myocardial infarction was 3.7 (95% CI 3.2, 4.2) times greater in Scotland than in southern England. In contrast, case fatality was significantly lower in Scotland: 18.5% (95% CI 13.1%, 25.0%), compared with 31.0% (95% CI 25.9%, 36.0%) in southern England. CONCLUSIONS: The incidence of myocardial infarction varied widely within the United Kingdom. Case fatality variation may reflect differences in ambulance response, or in diagnostic acumen, within the regions.

Adolescent↗
PubMed2000

Treatment of multiple sclerosis with interferon beta: an appraisal of cost-effectiveness and quality of life.

OBJECTIVE: To evaluate the cost-effectiveness of interferon beta-1b (IFbeta-1b) for relapsing-remitting multiple sclerosis (RRMS). METHODS: Construction of a cost-effectiveness model using published data on IFbeta-1b effectiveness and the natural history of RRMS, and new data on costs and quality of life (QoL) from a sample of 102 patients with RRMS and resident in northern England. RESULTS: Poorer QoL was found for patients with multiple sclerosis compared with the general population; those who had had a relapse; those with worse states identified by a clinical measure (expanded disability status scale (EDSS)). Relapses have effects over several months. Health state valuations were higher than in the general population. Costs were higher in relapse than remission and for worse EDSS states. IFbeta-1b costs were larger than cost savings. The best cost-effectiveness estimate was pound28 700 per relapse avoided, which is pound809 900 per QALY gained; or pound328 300 per QALY gained allowing for effects of progression over 5 years. Estimates were robust to changes in assumptions. CONCLUSIONS: The impact of multiple sclerosis on QoL is substantial. Future trials should base outcomes measurement on QoL and be better linked to natural history and cost data. IFbeta-1b produces important occasional short term QoL gains, but small gains in QALYs overall and large additional costs.

Adjuvants, Immunologic↗
PubMed2000

Reiter's syndrome following intravesical BCG immunotherapy.

A 71 year old woman developed conjunctivitis, asymmetrical oligoarthritis, and cystitis (Reiter's syndrome) secondary to intravesical BCG treatment for transitional cell carcinoma of the bladder. She received oral prednisolone, izoniazid, and pyridoxine and made a full recovery. Increasing use of BCG as immunotherapy will lead to an increase in the incidence of BCG associated reactive arthritis. Prompt recognition and early diagnosis will facilitate treatment and recovery.

Aged↗
PubMed2000

Medicinal maggots: an ancient remedy for some contemporary afflictions.

Certain fly larvae can infest corpses or the wounds of live hosts. Those which are least invasive on live hosts have been used therapeutically, to remove dead tissue from wounds, and promote healing. This medicinal use of maggots is increasing around the world, due to its efficacy, safety and simplicity. Given our low cultural esteem for maggots, the increasing use and popularity of maggot therapy is evidence of its utility. Maggot therapy has successfully treated many types of chronic wounds, but much clinical and basic research is needed still. In this review, the biology of myiasis and the history of maggot therapy are presented, the current status of our understanding and clinical use of medicinal maggots is discussed, and opportunities for future research and applications are proposed.

Animals↗
PubMed2000

Lack of peripheral neuropathy in Beagle dogs after 53 weeks oral administration of thalidomide capsules.

Thalidomide (Thalomid) is approved for use in the US to treat complications from leprosy. Peripheral neuropathy is a dose-limiting adverse event in humans. As part of a nonrodent regulatory toxicology study, Beagle dogs were fed orally via encapsulation for 53 weeks. A component of this study was to determine if the dogs developed peripheral neuropathy. Twenty-eight male and 28 female Beagle dogs approximately 8-10 months of age were used. They were dosed at 43, 200 or 1000 mg/kg for 53 weeks followed by a 4-week treatment-free recovery period. Nerve function was assessed by electrophysiological measurements of the tibial nerve prior to dosing and at weeks 13, 27, 38 and 51. Representative dogs from each group were sacrificed at 26, 53 and 58 weeks and histologic and ultrastructural evaluations were performed on the sural nerve. Thalidomide had no effect on sensory nerve conduction velocity, duration or amplitude of the action potential. At 27 weeks, mean sensory nerve action potential amplitude for females at 43 mg/kg was significantly greater than control but was not evident at 39 weeks. Mean duration of sensory nerve action potential seemed to increase with similar magnitude over time in all dose groups including controls. Histological and ultrastructural evaluation of sections of sural nerve did not identify treatment-induced differences between control and thalidomide-dosed animals after 26 and 53 weeks of treatment. Additionally, no differences were observed following a 5-week treatment-free period at week 58. In contrast to humans, Beagle dogs did not develop thalidomide-induced peripheral neuropathy under conditions of the study.

Action Potentials↗
PubMed2000

Auditory brainstem implants: current neurosurgical experiences and perspective.

The objective of this study was to present aspects of the current treatment protocol, such as patient evaluation and selection for therapy, multimodality monitoring for optimal auditory brainstem implant (ABI) positioning and radiological evaluation, that might have an impact on the functional results of ABI. Out of a series of 145 patients with bilateral vestibular schwannomas 10 patients received an ABI, eight of which are reported here. Patient selection was based on disease course, clinical and radiological criteria (according to the Hannover evaluation and prognosis scaling of neurofibromatosis type 2 (NF2)), extensive otological test battery and psycho-social factors. ABI placement was controlled by multimodality electrophysiological monitoring in order to activate the auditory pathway and to prevent false stimulation of the cranial nerve nuclei or long sensory or motor tracts. Results of hearing function were correlated with patients' ages, duration of deafness, tumour extension, tumour-induced compression or deformation of the brainstem, and numbers of activated electrodes without any side-effects. Out of 59 patients with pre-operative deafness eight patients received an ABI of the Nucleus 22 type. All these patients became continuous users without any side effects and experienced improved quality of life. Speech reception in combination with lip-reading was markedly improved, with further improvement over a long period. A short duration of deafness may be favourable for achieving good results, while age was not a relevant factor. Lateral recess obstruction may necessitate a more meticulous dissection, but did not prevent good placement of the ABI in the lateral recess. Pre-existing brainstem compression did not prevent good results, but brainstem deformation and ipsi- and contralateral distortion were followed by a less favourable outcome. Among the factors that can be influenced by the therapy management are the selection of patients with a slow progressing NF2 disease, a short duration of deafness, a careful analysis of brainstem deformation and consideration of either side for implantation. Long-standing brainstem deformation might not lead to recovery, but instead lead to a low number of active electrodes and possibly only moderate results. ABI treatment is a safe procedure that can increase a patient's quality of life considerably. ABI placement along with neurophysiological control helps to prevent side effects and to improve acoustic activation. Further studies on structural and functional changes of the brainstem after previous tumour compression and distortion should increase our understanding and facilitate a decision on the best side for ABI implantation.

Adult↗