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Biomedical subjects

S Thomas

Publications and source records attributed to S Thomas.

At least 289 records · Page 16Linked to original sources
PubMed1998

Traumatic brain injury in the developing rat pup: studies of ICP, PVI and neurological response.

Diffuse brain swelling is a common complication in young victims of a seven head injury but, there is a lack of data on relevant models of injury. We produced diffuse brain injury in 21 day old Lewis rat pups (N = 33) by modifying a recently established weight-drop-model. The trauma threshold, neurological response, histological changes, intracranial pressure (ICP), and arterial blood pressure (ABP) were determined. In addition, the pressure-volume-index (PVI) was measured 15 min before, 2 min, and 1 h after brain injury. In the 1 m/100 g group 4 of 5 rats died, whereas in the 0.5 m/100 g only 4 of 28 died. The PVI increased at 2 min after traumatic brain injury (TBI) but ICP was unchanged, except for a minor increase immediately after injury. Histological studies revealed diffuse neuronal death, predominantly involving the cortex and hippocampus. The results of the present study indicate that determination of ICP in the developing rat pup during and after diffuse brain injury is possible. A 0.5 m/100 g weight-drop-trauma results in a morphologically severe injury but with low mortality. The increase in PVI can be attributed to a decrease of cerebral perfusion pressure (CPP) after injury. However, the absence of a further increase of ICP after injury in the developing rat indicates that this may not be a primary consequence of injury in paediatric patients.

Age Factors↗
PubMed1998

CSF dynamics in a rodent model of closed head injury.

Using ICP measurements and the bolus injection technique dynamic parameters of the cerebrospinal fluid system as there are pressure-volume-index (PVI) and resistance to CSF outflow (Rout) were investigated in a new model of diffuse closed head injury (CHI) in the rat. It was found that in the absence of brain oedema and ICP alterations an increase in PVI and Rout was present in the early (4h) period following head injury. This may be indicative for a reduction in cerebral blood flow and cerebral blood volume, both shown previously to occur after CHI. Furthermore an early impairment of CSF absorption mechanisms is evident. To answer the question, whether bolus injection techniques are advisable for clinical routine and whether results might have a predictive value, further investigations covering longer observation intervals and in the presence of secondary insults to the brain are necessary.

Animals↗
PubMed1998

Practical approach to quality of life in Parkinson's disease: the nurse's role.

In recent years it has become apparent that nurses have several key roles in the treatment of Parkinson's disease. These include the practice of skilled clinical care, the provision of advice and education, communicating with patients and carers, and also between health and social care agencies. Their goals are to facilitate good clinical care, to reduce morbidity (both physical and psychological) and to achieve better informed patients by the reduction of misinformation, fear and distress caused by the diagnosis and consequences of this disease. The overall goal is to improve the prognosis and to reduce the impact of this disease on patients and their care givers. To achieve these goals the specialist nurse needs skills in assessment, reassessment and counselling in addition to knowledge of the disease and its management. The training needs have been established for the nursing profession to address these issues, and courses have been established and approved. A scale comprising four clinical management stages has been proposed: initially around the time of diagnosis; stable maintenance therapy; a more complex management stage, and palliative care. Nursing interventions and priorities differ in these arbitrary stages. Several models of nursing provision have been piloted in the United Kingdom, and results of evaluations are keenly awaited. Meanwhile, specialist nurses are proving to be popular with patients and carers, medical specialists, and the Parkinson's Disease Society which aims to see their provision in each Health District throughout the United Kingdom. In summary, the nursing role is complementary to those of the other members of the multi-disciplinary health team that aims to improve the quality of life of PD patients and their carers.

Disease Management↗
PubMed1998

Gene structure and map location of the murine homolog of the Huntington-associated protein, Hap1.

Huntington's Disease (HD) is an inherited progressive neurodegenerative disorder associated with a mutation in a gene expressed in both affected and non-affected tissues. The selective neuropathology in HD is thought to be mediated in part through interactions with other proteins including the Huntington Associated Protein, HAP-1, which is predominantly expressed in the brain. We have mapped its murine homolog, Hap1, to mouse Chr 11 (band D), which shares extensive synteny with human Chr 17 including the region 17q21-q22, where the gene for 'frontotemporal dementia and parkinsonism linked to chromosome 17' has bee mapped. In addition, we have sequenced a 21,984 base pair (bp) genomic clone encompassing the entire Hap1 gene. It is organized as 11 exons and flanked by exons from potentially one or more novel genes. At least three Hap1 transcripts (Hap1-A; Hap1-B; Hap1-C) can be formed by alternative splicing at the 3' end of the gene leading to protein isoforms with novel C-termini.

Algorithms↗
PubMed1998

Comprehensive multimodality blood conservation: 100 consecutive CABG operations without transfusion.

BACKGROUND: Despite the recent introduction of a number of technical and pharmacologic blood conservation measures, bleeding and allogeneic transfusion remain persistent problems in open heart surgical procedures. We hypothesized that a comprehensive multimodality blood conservation program applied algorithmically on the basis of bleeding and transfusion risk would provide a maximum, cost-effective, and safe reduction in postoperative bleeding and allogeneic blood transfusion. METHODS: One hundred consecutive patients undergoing coronary artery bypass grafting were prospectively enrolled in a risk factor-based multimodality blood conservation program (MMD group). To evaluate the relative efficacy and safety of this comprehensive approach, comparison was made with a similar group of 90 patients undergoing coronary artery bypass grafting to whom the multimodality blood conservation program was not applied but in whom an identical set of transfusion guidelines was enforced (control group). To evaluate the cost effectiveness of the multimodality program, comparison was also made between patients in the MMD group and a consecutive series of contemporaneous, diagnostic-related group-matched patients. RESULTS: One hundred consecutive patients in the MMD group underwent coronary artery bypass grafting without allogeneic transfusion. This compared favorably with the control population in whom a mean of 2.2 +/- 6.7 units of allogeneic blood was transfused per patient (34 patients [38%] received transfusion). In addition, the volume of postoperative blood loss at 12 hours in the control group was almost double that of the MMD group (660 +/- 270 mL versus 370 +/- 180 mL [p < 0.001]). Total costs for the MMD group in each of the three major diagnostic-related groups were equivalent to or significantly less than those in the consecutive series of diagnostic-related group-matched patients. CONCLUSIONS: Comprehensive risk factor-based application of multiple blood conservation measures in an optimized, integrated, and algorithmic manner can significantly decrease bleeding and need of allogeneic transfusion in coronary artery bypass grafting in a safe and cost-effective manner.

Algorithms↗
PubMed1998

Refined tuberculosis contact tracing in a low incidence area.

Our aim was to evaluate the efficacy of a revised tuberculosis (TB) contact tracing procedure in South Glamorgan whereby routine annual radiological surveillance was abandoned and contacts were either discharged or referred to chest clinic following their initial screening. We reviewed and evaluated data from the TB contact tracing clinic, the Public Health Service Mycobacterium Reference Unit, Cardiff and the Consultant in Communicable Diseases Control, South Glamorgan Health Authority and compared these results with those of our previous study. One hundred and three index cases and 732 contacts were identified. Seven hundred and seven contacts, 526 close and 181 casual, were screened, of whom 102 casuals should not have been. One hundred and sixty-one contacts were given BCG vaccination. Fifty-four contacts were referred to the chest clinic. Seven cases of TB were detected, all in young, unvaccinated, close contacts of pulmonary disease. Twenty-one contacts were given chemoprophylaxis, 20 of whom were close contacts of pulmonary TB and one of extrapulmonary disease. Five contacts who were screened and initially discharged developed TB later: in two the protocol had not been followed and three presented with extrapulmonary TB. Compared with the results of the previous protocol fewer contacts were unnecessarily screened and referrals to the chest clinic increased, as did the number given chemoprophylaxis. The case finding rate is similar to that found prior to the revision of the protocol. The yield from tracing casual contacts continues to be nil. It is very low in contacts of extrapulmonary disease. When the protocol was followed no case of pulmonary TB was missed. The revised protocol seems to be as effective as the previous, more complex protocol. In our area, one of low incidence of TB, screening of casual contacts and of contacts of extrapulmonary TB is not cost-effective. We will concentrate even more on screening close contacts of pulmonary TB.

Adolescent↗
PubMed1998

Observations on mattress covers: results of a pilot study.

Samples of covers from three commercially available mattresses were examined in the laboratory using test methods originally devised for testing surgical dressings. These revealed that although the covers shared many common features, there were differences in the conformability and tensile properties which may be of some clinical relevance. The study also confirmed that with some minor modifications, the experimental techniques used would be suitable for a future, more comprehensive review of mattress performance. In a separate investigation designed to examine the consequences of a failure of a mattress cover, the bioburden of a foam core removed from a damaged cover revealed the presence of very large numbers of microorganism, well in excess of 10(10) per gram of foam which could act as a recevoir of contamination and thus a source of cross infection.

Bedding and Linens↗
PubMed1998

Fish red blood cells: characteristics and physiological role of the membrane ion transporters.

Several membrane ion transporters playing a role in gas transport and exchanges, cell volume regulation and intracellular acid-base regulation have been identified in fish red blood cells (RBCs). This short review focuses on Na+/K+ATPase and its role in establishing the ionic gradients across the membrane, on the Cl-/HCO3- exchanger and its key role in respiration and possibly in inducing a chloride conductance, on the Na+/H+ exchanger and the recent advances on its molecular mechanisms of activation and regulation, on the different types of K-Cl cotransports, the different hypotheses and suggested models and their role in cell volume regulation. There is no evidence in the literature for ionic channels in fish RBCs. We present original data obtained with the patch-clamp technique that shows for the first time the existence of a DIDS-sensitive chloride anionic conductance measured in whole cell configuration and the presence of a stretch-activated nonselective cationic channel recorded in cell-attached and excised inside-out configuration. The part played by these ionic conductances is discussed in relation with their possible involvement in volume regulation.

Animals↗
PubMed1998

Viral haemorrhagic disease of rabbits and human health.

Viral haemorrhagic disease of rabbits (VHD), a potential biological control for wild rabbits in Australia and New Zealand, escaped from quarantined field trials on Wardang Island and spread to the mainland of Australia in October 1995. This study looked for any evidence of infection or illness in people occupationally exposed to the virus. Two hundred and sixty-nine people were interviewed and 259 blood samples were collected. Exposures to VHD-infected rabbits ranged from nil to very high. No VHD antibodies were detected in any of the 259 sera when tested by VHD competitive enzyme immunoassay, which had been validated with 1013 VHDV-specific antibody negative sera. A questionnaire designed to elicit symptoms of disease in a range of organ systems found no significant differences between illness in those exposed and those not exposed to VHD, nor could an association be found between exposure and subsequent episodes of illness. The findings are consistent with the view that exposure to VHD is not associated with infection or disease in humans.

Animals↗
PubMed1998

Face-to-face confrontation: effects of closed-circuit technology on children's eyewitness testimony and jurors' decisions.

The present study was designed to examine effects of closed-circuit technology on children's testimony and jurors' perceptions of child witnesses. For the study, a series of elaborately staged mock trials was held. First, 5- to 6-year-old and 8- to 9-year-old children individually participated in a play session with an unfamiliar male confederate. Approximately 2 weeks later, children individually testified about the event at downtown city courtroom. Mock juries composed of community recruits viewed the trials, with the child's testimony presented either live in open court or over closed-circuit television. Mock jurors made ratings concerning the child witness and the defendant, and deliberated to reach a verdict. Results indicated that overall, older children were more accurate witnesses than younger children. However, older, not younger children produced more inaccurate information in free recall. Compared to live testimony in open court, use of closed-circuit technology led to decreased suggestibility for younger children. Testifying in open court was also associated with children experiencing greater pretrial anxiety. Closed-circuit technology did not diminish fact finders' abilities to discriminate accurate from inaccurate child testimony, nor did it directly bias jurors against the defendant. However, closed-circuit testimony biased jurors against child witnesses. Moreover, jurors tended to base their impressions of witness credibility on perceived confidence and consistency. Implications for the use of closed-circuit technology when children testify are discussed.

Adult↗
PubMed1998

Antithrombotic activity of a fucosylated chondroitin sulphate from echinoderm: sulphated fucose branches on the polysaccharide account for its antithrombotic action.

The antithrombotic activity of a fucosylated, chondroitin-sulphate-like polysaccharide extracted from the body wall of sea cucumber, and of chemically modified derivatives of the same polysaccharide, have been assessed using a stasis thrombosis model in rabbits. Intravenous administration of the native polysaccharide reduced thrombosis in a dose-dependent manner and, at a dose of 1.5 mg/kg (60 IU/kg) body weight, completely prevented thrombosis after 10 min stasis. Removal of the sulphated fucose branches of the polysaccharide abolished antithrombotic effectiveness. After intravenous injection of an antithrombotic dose of radioactively labelled polysaccharide, a correlation was observed between removal of radioactivity from the plasma and decrease in ex vivo APTT values, demonstrating that antithrombotic effectiveness depends on the level of circulating polysaccharide rather than on an indirect effect of the polysaccharide on the vascular endothelium. Reduction of the glucuronic acid carboxyl groups in the polysaccharide did not affect its in vitro and in vivo activities. Both partial defucosylation and desulphation of the polysaccharide abolished all its anticoagulant or antithrombotic action.

Animals↗
PubMed1998

It hurts most around the heart: a phenomenological exploration of women's anger.

Women's anger experience has been poorly understood and insufficiently researched. Yet the emotion of anger is vitally important to women's physical and mental health, and to the quality of their relationships. This phenomenological study was undertaken as an expansion and extension of the Women's Anger Study, the first large survey of the genesis, manifestations and correlates of anger in American women. Although the earlier study contributed to understanding of anger, a deeper examination of the context and meanings of anger experience was sought. Twenty-nine Caucasian women ranging in age from 21 to 66 years were interviewed. Illustrative occupations ranged from homemaker, student, waitress to business executive, professor, and human service professional. Analysis involved thematizing by the researchers independently and within a multidisciplinary phenomenological research group. The thematic structure of women's anger involved a building over time of a confusing mixture of feelings (hurt, frustration, disillusionment) precipitated by a violation of the core values of the self. The precipitant of anger was unfair and/or disrespectful treatment or lack of reciprocity in relationships. When the anger was confined within self, the woman felt helpless and powerless. However, powerlessness was also evident when anger was externalized in an outburst. To the study participants, an angry outburst meant a loss of control rather than ability to achieve control. Women reported a sense of power when using anger to restore justice, respect, and relationship reciprocity. Clinicians can assist women to reflect on their core values and use the power of their anger effectively. Further studies are in progress to examine the relevance of these findings for women of other races and cultural contexts.

Adaptation, Psychological↗
PubMed1998

Psychological and socio-medical aspects of HIV/AIDS: a reflection on publications in AIDS care (1989-1995).

It is necessary to consider the content and methods of AIDS social research publications for these represent research advances as well as current issues of concern for practitioners, communities and researchers alike. This article critically examines some of the research that has been conducted to date into social aspects of HIV and AIDS. It quantifies the content and major methodological style of publications in the journal AIDS Care from 1989 to 1995. The most commonly published topic area in AIDS Care, during this period was cultural and demographic issues (15.9%), followed by issues pertinent to the psychological impact of HIV (13.6%), sexual behaviour and condom use (11.3%) and policy and services (9.5%). Research and measurement issues were the least examined content area in AIDS Care 1989-1995 (2.6%). This article discusses possible variables that influence the style and topics that are published in AIDS Care and makes suggestions for authors to consider before embarking on future research projects or publications.

Acquired Immunodeficiency Syndrome↗
PubMed1998

Katanin is responsible for the M-phase microtubule-severing activity in Xenopus eggs.

Microtubules are dynamic structures whose proper rearrangement during the cell cycle is essential for the positioning of membranes during interphase and for chromosome segregation during mitosis. The previous discovery of a cyclin B/cdc2-activated microtubule-severing activity in M-phase Xenopus egg extracts suggested that a microtubule-severing protein might play an important role in cell cycle-dependent changes in microtubule dynamics and organization. However, the isolation of three different microtubule-severing proteins, p56, EF1alpha, and katanin, has only confused the issue because none of these proteins is directly activated by cyclin B/cdc2. Here we use immunodepletion with antibodies specific for a vertebrate katanin homologue to demonstrate that katanin is responsible for the majority of M-phase severing activity in Xenopus eggs. This result suggests that katanin is responsible for changes in microtubules occurring at mitosis. Immunofluorescence analysis demonstrated that katanin is concentrated at a microtubule-dependent structure at mitotic spindle poles in Xenopus A6 cells and in human fibroblasts, suggesting a specific role in microtubule disassembly at spindle poles. Surprisingly, katanin was also found in adult mouse brain, indicating that katanin may have other functions distinct from its mitotic role.

Adenosine Triphosphatases↗
PubMed1998

A comparative in vitro study of the frictional characteristics of two types of self-ligating brackets and two types of pre-adjusted edgewise brackets tied with elastomeric ligatures.

The aim of this in vitro study was to investigate the frictional characteristics of two types of self-ligating brackets ('A' Company Damon SL and Adenta Time brackets) and two types of pre-adjusted edgewise brackets (TP Tip-Edge and 'A' Company Standard Twin brackets). The test brackets were glued to steel bars and aligned using a preformed jig. Five combinations of archwire size and material were used (0.014-inch nickel titanium, 0.0175-inch multistrand stainless steel, 0.016 x 0.022-inch nickel titanium, 0.016 x 0.022-inch stainless steel and 0.019 x 0.025-inch stainless steel wires). The wires were drawn through the brackets and the frictional resistance was measured using an Instron 1193 testing machine. The data were analysed using a one-way analysis of variance and Scheffe's multiple comparison of means test. The results revealed that the Damon brackets demonstrated the lowest friction for all dimensions of test wires followed by the Time bracket. The 'A' Company Standard Twin brackets produced the highest friction with all wire dimensions tested, followed by the Tip-Edge bracket. With all brackets the 0.016 x 0.022-inch nickel titanium wires produced a higher frictional resistance than the 0.016 x 0.022-inch stainless steel wires. The results indicate that these self-ligating brackets produce less frictional resistance than elastomerically-tied pre-adjusted edgewise brackets.

Analysis of Variance↗