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Biomedical subjects

P Harris

Publications and source records attributed to P Harris.

At least 109 records · Page 6Linked to original sources
PubMed1996

Interposition vein cuffs.

A vein cuff interposed at the distal anastomosis between a prosthetic vascular graft and a recipient infrageniculate artery improves the chances of continued patency of the graft, at least in the short and medium term. The mode of effect appears to be suppression or modification of anastomotic myointimal hyperplasia (MIH). In the event of graft failure the recipient artery and run-off vessels remain free from MIH and their patency is preserved thereby improving the prospects for further vascular reconstruction and limb salvage. The mechanisms by which interposition vein cuffs might modulate MIH are reviewed. Experimental evidence is described to show that the geometry of a cuffed anastomosis promotes a characteristic haemodynamic flow structure with a stable vortex. It is suggested that this vortex exerts greater shear stress upon the wall of the artery than the normal laminar flow observed in conventional anastomoses. High shear stress is known to inhibit MIH.

Anastomosis, Surgical↗
PubMed1996

IL-4 induced leucocyte trafficking in cynomolgus monkeys: correlation with expression of adhesion molecules and chemokine generation.

BACKGROUND: Interleukin-4 (IL-4) is an immunoregulatory cytokine which has a wide variety of effects on immune cell function. In addition, recent studies suggest that IL-4 may have effects on other cells including endothelial cells in terms of the regulation of adhesion molecule expression and leucocyte extravasation from the vascular space to sites of tissue inflammation. Consequently, IL-4 may have an important role in the pathogenesis of allergic inflammation and disease. OBJECTIVE: The purpose of this study was to learn more about the potential role of IL-4 in inflammatory disease, specifically in regard to the potential of IL-4 to induce the expression of adhesion molecules on vascular endothelial cells and promote the adherence and transmigration of circulating leucocytes to sites of tissue inflammation. METHODS: Single subcutaneous injections of human IL-4 were administered to cynomolgus monkeys and tissue biopsy samples were obtained and analysed for adhesion molecule expression on vascular endothelium and inflammatory cell infiltrates. In another series of experiments, multiple subcutaneous injections of human IL-4 were administered (bid on four consecutive days) and the effects on peripheral blood leucocytes and plasma levels of various cytokines and chemokines were examined. RESULTS: Intradermal injection of IL-4 induced the expression of vascular cell adhesion molecule-1 (VCAM-1) on cutaneous vascular endothelium that was present at 8 hr and persisted out to 24 h post injection. The expression of VCAM-1 was associated with an inflammatory cell infiltrate comprised of granulocytes and mononuclear cells. Multiple injections of IL-4 resulted in a dose-related decrease in the relative percentage and total number of circulating lymphocytes and an increase in circulating neutrophils (4.6 +/- 1-2.1 +/- 0.2 x 10(6)/mL and 1.7 +/- 0.3-7.0 +/- 1 x 10(6)/mL, respectively). Analysis of cell surface markers by flow cytometry revealed a transient decrease in the number of CD4+T lymphocytes and a sustained decrease in CD16+ cells. In addition, IL-4 administration resulted in a large increase in plasma MCP-1 concentration. CONCLUSION: This is the first study to demonstrate an acute effect of IL-4 consistent with lymphocyte trafficking out of the vascular space, the induction of VCAM-1 expression on vascular endothelium and increases in plasma levels of MCP-1 in vivo. We suggest that IL-4 may be involved in the early recruitment of mononuclear cells to sites of tissue inflammation by the upregulation of VCAM-1 expression on vascular endothelium and the generation and release of potent chemoattractants.

Animals↗
PubMed1996

Becoming a GP facilitator. A training approach.

The UNSW School of Medical Education has devised a training program for general practitioners to develop skills as GP facilitators involved with small groups in Continuing Medical Education programs and was offered in 1994. This program was well received by the participants and further developments are under way. Prior research on the most effective CME strategies for general practitioners confirms the value of this approach.

Adult↗
PubMed1995

Assessment of the value of the immediate postoperative chest radiograph after cardiac operation.

The value of the immediate postoperative chest radiograph upon a patient's return to the intensive care unit after a cardiac surgical procedure is uncertain. This study represents a prospective analysis of the immediate postoperative radiograph in 100 consecutive adult patients undergoing cardiac operations. In 11 patients it was found that the routine postoperative radiograph was of value when it was necessary either to clarify or confirm clinical findings or to check the position of an intraaortic balloon catheter. For those chest radiographs that were deemed unnecessary, only one of 89 were found to be of clinical value. Furthermore, in those situations in which an emergency radiograph was obtained, the routine radiograph was not found to be contributory to patient management. We conclude that the policy of obtaining routine, immediate postoperative chest radiographs in the absence of a specific clinical indication provides virtually no additional clinical yield. Residents should therefore request radiographs only to check the position of an intraaortic balloon catheter, and to clarify or confirm a clinical diagnosis.

Adult↗
PubMed1995

Nocardia asteroides purulent pericarditis.

A case is reported of a 71-year-old woman who developed cardiac tamponade as a result of a pyopericardium. The causative organism was Nocardia asteroides. This is the first reported case in the United Kingdom and only the 9th to be reported in the world. Despite prior radiological and echocardiographic investigations, we were unprepared at surgery for the volume of pus encountered. The dense adhesions, adherent pericardium and loculations encountered emphasizes the need to explore such patients surgically. We would advocate vigilance as to the possibility of pericardial involvement, in any patient contracting Nocardia asteroides infection. The medical and surgical management of this case is discussed together with a review of the literature.

Aged↗
PubMed1995

Use of continuous human lung cell culture for adenovirus isolation.

Adenovirus sensitivity, TCD50 value and mean time to cytopathic effect (CPE) were compared in Madin-Darby canine kidney (MDCK), rhesus monkey kidney (RhMK), human lung carcinoma (A549) and in newly identified continuous human lung (CHL) cell cultures. High-titer stock and positive original specimens were inoculated in culture. Patients specimens were also placed in shell-vial cultures. A549 and CHL cells demonstrated comparable sensitivity, however the former generally produced CPE earlier. Sensitivity was respectively reduced and poor in RhMK and MDCK cultures, as expected in cells of nonhuman origin. The performance of CHL for adenoviruses and other pathogens makes them a useful addition in diagnostic virology laboratories.

Adenoviruses, Human↗
PubMed1995

Multiparameter flow cytometric DNA analysis of effusions: a prospective study of 36 cases compared with routine cytology and immunohistochemistry.

Single-parameter flow cytometry (SFCM) is limited in its ability to detect aneuploid and diploid malignant cells or accurately estimate S-phase fractions (SPF) in effusions because of the high degree of contamination by benign mesothelial cells and inflammatory cells. We examined 36 pleural and peritoneal fluids by conventional cytology and multiparameter FCM (MFCM) to analyze the DNA content of cells expressing epithelial markers cytokeratin, epithelial membrane antigen, carcinoembryonic antigen, BRST-1, or BRST-3 (B72.3) and compared the results to those found with SCFM. The cases were also studied by immunohistochemistry using the same antibody panel. By routine cytology, 14 of the 36 cases were classified as carcinomas, 11 as reactive, 1 as mesothelioma, and 10 as suspicious. MFCM allowed reclassification of 5 of the 10 suspicious cases as carcinomas and the remaining 5 as reactive cases based on ploidy and marker expression. Whereas SFCM detected only 13 nondiploid carcinomas, MFCM detected 4 diploid and 15 nondiploid carcinomas. All reactive cases were diploid by SFCM or MFCM. The mesothelioma case showed were distinct peaks by MFCM, a diploid peak with SPF of 13.4% and a tetraploid peak with SPF of 36.1%. The SPF of the nondiploid carcinomas ranged from 5.9 to 50.4% and diploid carcinomas, from 3.5 to 14.5% when gated on epithelial cells. The reactive cases had SPF ranging from 0.4 to 4.4%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗
PubMed1994

The problem of defining heart failure.

A succession of theories arising from last century has attempted to explain why patients with damaged hearts develop peripheral edema. Opposed to the original simple concepts of backward failure, a number of theories of forward failure have been proposed, the cardiac output being considered inadequate for capillary permeability, renal function, or the metabolic needs of the body. Any theory needs to take account of the neuroendocrine stimulation now known to occur under these conditions. This article presents evidence for the belief that the condition arises when the cardiac output becomes insufficient to maintain the arterial blood pressure without the support of excessive neuroendocrine activity. This explains why the edematous state may be evoked in patients who have a severe reduction in peripheral resistance as well as in those with a reduced cardiac output. While the clinical concept of cardiac failure arose from the consideration of the formation of edema in patients with cardiac disease, the term has also come to be used by laboratory investigators studying the immediate effects of reducing the strength of ventricular contraction. The application of the same name to two different conditions has led to confusion, and this review stresses the importance of definition of terms.

Blood Pressure↗
PubMed1994

Comprehension of pretense in children with autism.

In an attempt to tap underlying competencies, the ability of children with autism to comprehend pretend acts carried out by an experimenter was compared with that shown by controls. These acts consisted of the pouring of a pretend substance from an appropriate container onto a target figure. There was no significant difference in the groups' ability to identify the pretend substance involved, to predict the pretend outcome of the actions, or to reflect on the pretend nature of the episodes. However, the performance of controls on these latter two tasks was surprisingly poor, limiting the implications that might be drawn from the observed absence of group differences in comprehension abilities.

Adolescent↗
PubMed1994

The illusion of control and optimism about health: on being less at risk but no more in control than others.

If unrealistic optimism is simply a manifestation of the illusion of control (McKenna, 1993), differences in estimates of the likelihood of events for the self and others (comparative optimism) should have concomitant differences in perceived capacity to control these events. This possibility was tested in the domain of health, along with Perloff & Fetzer's (1986) risk-factor version of this downward comparison hypothesis and the hitherto neglected possibility that unrealistic optimism is an artifact of the comparative procedures employed in studies to date. It was found that likelihood judgements for a range of illnesses tended to be significantly lower when made by subjects providing self-ratings than when made by those providing judgements for the 'typical' student and, to a lesser extent, those making judgements for a friend's friend, but not by those doing so for an acquaintance. This comparative optimism was associated with equivalent differences in perceptions of these targets on a selection of relevant risk factors, but not in ratings of their capacity to control these outcomes (for which there was consensus across targets). The data are thus consistent with the risk-factor version of the hypothesis rather than the control version or the artifact explanation. The theoretical implications of these findings are addressed along with their consequences for health promotion.

Adult↗