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Biomedical subjects

J M Clark

Publications and source records attributed to J M Clark.

323 records · Page 18Linked to original sources
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Breath biomarkers and non-alcoholic fatty liver disease: preliminary observations.

Breath biomarkers have the potential to offer information that is similar to conventional clinical tests or they are entirely unique. Preliminary data support the use of breath biomarkers in the study of liver disease, in particular non-alcoholic fatty liver disease (NAFLD). It was evaluated whether breath ethanol, ethane, sulfur compounds and acetone would be associated with hepatic histopathology amongst morbidly obese patients presenting for bariatric surgery. Breath samples were collected during a preoperative visit and compared with liver biopsies obtained during the surgery. A Student's two-tailed t-test was used to compare differences between the two groups. Linear regression was used to analyse associations between the concentrations of breath molecules and independent predictor variables. It was found that breath ethanol, ethane and acetone can be useful biomarkers in patients with NAFLD. In particular, breath ethanol can be associated with hepatic steatosis, and breath acetone can be associated with non-alcoholic steatohepatitis.

Acetone↗
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NMDA lesions of rat lateral hypothalamus: effects of dietary and physiological challenges.

Rats bearing NMDA lesions of the lateral hypothalamus (LH) were tested for their reactions to alterations in the sensory (but not calorific) content of the diet (finickiness), to 24 h food or water deprivation, and to dehydrating injections of hypertonic saline and glucoprivic injections of 2-deoxy-D-glucose (2-DG). Lesioned rats lost weight following surgery but had no significant eating or drinking difficulties in the home cage. They were not finicky and responded normally to 24 h food or water deprivation. Responses to hypertonic saline and 2-DG challenges were significantly impaired. These data suggest a subtle motivational disorder following LH lesion, rather than motor or sensory impairment.

Animals↗
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A preliminary study of joint surface changes after an intraarticular fracture: a sheep model of a tibia fracture with weight bearing after internal fixation.

OBJECTIVE: To evaluate the changes in the articular cartilage and subchondral bone after an osteotomy designed to simulate an articular fracture. DESIGN: The contribution of the cartilage and subchondral bone was evaluated twelve weeks after creating a 1.0-millimeter step-off in the medial plateau of the tibia of twelve adult domestic sheep. All animals surviving were labeled with fluorescent markers for bone production, oxytetracycline (fifty milligrams per kilogram), and calcein (twelve milligrams per kilogram) nine and 11.5 weeks after surgery. The knees were loaded in compression using an Instron materials tester with pressure-sensitive film to record joint contact pressures above and below the medial meniscus. SETTING: The studies were performed in the research laboratories of the Orthopaedic Laboratory at Harborview Medical Center in Seattle, Washington and the Madigan Army Medical Center in Tacoma, Washington. ANIMALS: Twelve adult domestic sheep. INTERVENTION: An intraarticular osteotomy of the medial tibial plateau with 1.0 millimeter of displacement was performed. The osteotomy was stabilized with 3.5-millimeter lag screws. MAIN OUTCOME MEASURES: The contact pressures of the knee joint and articular histology were evaluated twelve weeks after surgery. Samples of the articular cartilage were analyzed by light microscopy and electron microscopy to evaluate the response of the articular cartilage and subchondral bone of the differential joint loading because of the irregularity in the articular surface caused by the osteotomy. RESULTS: The knees with an intraarticular step-off had two major contact areas with an intervening zone of reduced load corresponding to the edge of the depressed fragment. Coronal histologic sections through the articular surface showed the presence of thinning and fibrillation on the high side of the step-off and some compensatory hypertrophy of the cartilage. The subchondral bone was not responsible for restoring articular congruity because the rate of bone production was similar between the low side of the articular fracture (1.85 micrometers per day) and the high side of the fracture (1.67 micrometers per day). Scanning electron microscopy showed partial cartilage remodeling by deformation of the high side cartilage with bending of the vertical collagen fibrils, even in the unloaded state. CONCLUSIONS: In this model with a small fracture displacement (1.0 millimeter), which was less than the thickness of the articular cartilage (1.5 millimeters), the contour of the joint improved despite residual articular surface incongruency after the fracture healing.

Animals↗
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Transmural organization of the arterial media. The lamellar unit revisited.

When scanning electron micrographs of orthogonal transmural fracture surfaces of distended aortas were compared with appearances on corresponding semithin light microscopic and ultrathin transmission electron microscopic sections, medial lamellar units could be resolved into composites of overlapping, musculo-elastic fascicles lying parallel to tangential planes of section. Each fascicle consisted of a group of commonly oriented, elongated smooth muscle cells and an encompassing array of branching, similarly oriented elastic fibers. On longitudinal sections of straight segments of the aorta, fascicles appeared as closely packed, transversely transected smooth muscle cell groups within compartments formed by similarly transected elastic fibers. On transverse sections, fascicles appeared as groups of cells within cell strips or layers, each of which was bracketed on both its luminal and abluminal sides by straight elastic fibers. Fascicles were increasingly evident during growth as commonly oriented groups of cells within the already present concentric cell layers became demarcated by enlarging elastic fibers. Wavy collagen fiber bundles, distinct from the interlaced fibrils of the immediate pericellular matrix, were interposed mainly between the facing elastin systems within the fibrous regions between cell layers. Thus, the radial transmural disposition of cells and matrix fibers on transverse sections of the media in well developed aortas proved to be: elastin-cells-elastin--collagen bundles--elastin-cells-elastin--collagen bundles, etc. Medias of major branch arteries were also composed of musculo-elastic fascicles, but their encompassing elastic fiber systems were less prominent than in the aorta. In straight segments of aortas and arteries, fascicles were uniform in size at any given transmural level and oriented mainly circumferentially. At bends and branch points fascicles were smaller and less uniform in size and orientation. In relation to changes in vessel wall curvature, alignment of the fascicles was usually in the direction of presumed resultant tensile stress. The findings suggest that these subunits of medial organization correspond to the distribution and magnitude of tensile stresses.

Animals↗
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Perceptions and practice of health education and heath promotion in acute ward settings.

This paper reports on an overview of the findings from a two-year Department of Health-funded research project. The study had two overall aims: to describe the extent to which health education and health promotion had become integrated into nurses' practice in acute-care settings and to identify the facilitative and inhibitory factors involved. The study comprised separate sequential stages of data collection and utilised a multi-method approach. Findings from a survey of ward sisters and from ward-based case studies are presented and discussed. These suggest that nurses have yet to fulfill their potential as educators and promoters of health and that a number of influences interact at ward level to encourage or impede the development of this role.

Health Promotion↗
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Making the transition from student to staff nurse.

Project 2000 was designed to provide a nursing workforce equipped with the flexibility and skills to adapt to changes in health care. This qualitative study explored how 10 diplomates fared after qualification. The findings, as part of a larger study, question what should be expected of newly qualified staff and the support they receive. Like traditionally trained nurses, they experienced the shock of increased responsibility, but they also faced negative attitudes because of their preparation. Despite a self-perceived lack of confidence, their willingness to question themselves and others suggests self-confident practitioners. A second paper, exploring the professional support of newly qualified staff, will appear later.

Education, Nursing, Continuing↗
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Preceptorship and support for staff: the good and the bad.

In this article the support received by 10 diplomates when starting their staff nurse posts is examined. In particular the potential role of preceptorship in facilitating a smooth transition is highlighted. This is the second of two articles, the first of which appeared in Nursing Times on October 30.

Education, Nursing, Continuing↗
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The impact of Project 2000.

The research study described here was commissioned by the English National Board to examine nursing in the context of Project 2000 implementation. The research team explored the impact of Project 2000 on students, managers and practitioners. Students and diplomates were perceived to be patient-oriented and holistic in approach; basic nursing care was identified as a central role of qualified nurses. Perceptions of nursing shifted as the course progressed to include health promotion, and research and theory as a basis for practice. Aspects of the course valued by students included the broader academic input, interpersonal skills, life sciences, supernumerary status and the challenging approach advocated by the course. Students were concerned about the timing of the biological science modules, which often did not coincide with their practice experiences. Students identified poor course organisation and poor teaching skills of some lecturers as areas for concern. Managers and practitioners identified students as potential agents of change who challenged traditional expectations of newly qualified nurses.

Clinical Competence↗