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Biomedical subjects

P Barron

Publications and source records attributed to P Barron.

35 records · Page 2Linked to original sources
PubMed1994

A shotgun marriage--community health workers and government health services. Qualitative evaluation of a community health worker project in Khayelitsha.

In 1988 the Western Cape Regional Services Council (RSC) initiated a community health worker (CHW) project in Khayelitsha in order to extend its preventive services to people in the community and promote 'community upliftment'. An evaluation of this project was undertaken in 1991 and 1992 in order to examine the potential of this local health authority-run CHW project to be an appropriate primary health care model. Qualitative research methods were used to explore the nature of the work done by the CHWs, whether they were accepted in their communities, and whether the project functioned as part of an integrated health service infrastructure in Khayelitsha. The CHWs were found to provide the basis for a potentially effective, community-responsive service. However, several structural problems mitigated against this service. Relations between the CHWs and nurses in all the formal public health services in the area were superficial and fraught with problems. There were significant differences and conflicting policies between the RSC's CHW project and other neighbouring non-government CHW projects, and these posed various threats to both the RSC and the non-government projects. One of the most serious of these differences was that the RSC project had no structures or plans for community involvement in the running of the project. Before a CHW project is initiated, several critical issues need to be carefully considered and discussed with all the relevant stakeholders. Furthermore, CHWs need to be flexible, and accountable to the communities in which they work. Before employing CHWs, formal public health authorities need to consider carefully whether they are able to meet these criteria.

Community Health Services↗
PubMed1994

Insulin sensitivity and glucose tolerance following transposition of pancreatic venous drainage to the systemic circulation.

In these studies it has been demonstrated that the diversion of pancreatic venous drainage to the systemic circulation (1) increases the peripheral insulinemia and metabolic clearance of glucose under basal conditions; (2) decreases insulin sensitivity, as measured by the hyperinsulinemic euglycemic clamp, more than 2-fold; and (3) decreases peripheral insulin sensitivity and the suppression of endogenous glucose production during exogenous glucose infusion. In spite of these changes, tolerance to the intravenously infused glucose improves. This is accounted for by higher insulin concentrations following diversion, more than compensating for decreases in insulin sensitivity and the suppression of endogenous glucose production. Data on insulin sensitivity and glucose tolerance after pancreas transplantation are not completely consistent, as discussed above. When the site of venous drainage of the pancreas was the only factor altered in the experimental model, unequivocal insulin resistance resulted. This occurred in a relatively short period (ie, 2 weeks). The results here are consistent with a number of studies that have demonstrated normal glucose tolerance coupled with hyperinsulinemia in a partially pancreatectomized dog model as well as in human pancreas transplants. Data presented here imply that the hyperinsulinemia which results after surgical diversion of the pancreatic venous drainage from the portal to the systemic circulation causes an important degree of insulin resistance. Physiological insulin delivery and therefore portal drainage during transplantation may therefore be relevant for the complete normalization of glucoregulation in diabetes. The reduction of hyperinsulinemia may also be important in light of the recent emphasis on the role that this and insulin resistance may play in the development of complications such as cardiovascular disease or hypertension.

Animals↗
PubMed1993

The effect of systemic venous drainage of the pancreas on insulin sensitivity in dogs.

To assess the metabolic consequences of the diversion of the pancreatic venous drainage to the systemic circulation, the pancreaticoduodenal and gastrosplenic veins were anastomosed to the inferior vena cava in nine normal dogs. This procedure maintained the integrity of the entire pancreas while shunting the hormonal output of the pancreas to the periphery. The metabolic effects were assessed from the sensitivity to insulin during a euglycemic hyperinsulinemic glucose clamp using an insulin infusion of 800 microU/kg per min. The studies were controlled by their duplication in seven dogs identically treated but with the pancreatic veins reanastomosed to the portal vein. No differences in systemic insulin levels or insulin sensitivity before and after surgery were seen under these circumstances. After diversion, however, basal insulin levels rose from 4.5 +/- 1.0 to 11.5 +/- 2.5 microU/ml. Basal glucose metabolic clearance rate (MCR) rose to 3.0 +/- 0.4 from 2.0 +/- 0.3 ml/kg per min. On insulin infusion, maximal stimulation of MCR within the 2-h infusion period was to 15.2 +/- 2.5 ml/kg per min preoperatively and to 7.2 +/- 0.8 ml/kg per min after diversion. Using ratios of MCR-to-insulin concentration as an index of insulin sensitivity, it was demonstrated that this index decreased by at least 50% after diversion. These data imply that portal venous drainage of the pancreas is an important factor in the determination of peripheral insulin sensitivity.

Anastomosis, Surgical↗
PubMed1993

Far fewer missed opportunities for immunisation in an integrated child health service.

The mobile nature of the population of Khayelitsha makes it imperative that opportunities for immunisation of children are exploited at every visit to health services. Previous studies have demonstrated a high incidence of missed opportunities for immunisation at curative health services. The occurrence of undetected opportunities for immunisation are compared at two primary care institutions: one in which curative and preventive services are provided separately, and one in which these functions are integrated. Far fewer opportunities for immunisation were missed at the integrated service, underscoring the urgency of integrating child health services throughout the country.

Child Health Services↗
PubMed1990

Occupational health services in Johannesburg and Randburg.

Questionnaires were posted to 760 manufacturing organisations sampled from the 1986 Workmen's Compensation tape in the Johannesburg and Randburg areas. A response rate of 51% was obtained. The results indicate a general deficiency in the quantity of occupational health services offered. For example, only 57 factories (18%) offered a medical service on the premises, while pre-employment examinations were provided by 59. More larger factories than smaller ones provided occupational health services. There were also variations in the occupational health benefits provided, and salaried employees were generally better off than wage earners. For example, 62 factories (25%) did not provide medical schemes for wage earners, while only 5 (2%) did not provide medical schemes for salaried employees. Since the Erasmus Commission's findings were published in 1976, there does not appear to have been a substantial change in the provision of occupational health services in the manufacturing industry. With increasing urbanisation it is important that something be done to improve this situation.

Occupational Health Services↗
PubMed1990

Immunologic defects following trauma: a delay in immunoglobulin synthesis by cultured B cells following traumatic accidents but not elective surgery.

The immune status of trauma patients was compared with that of elective surgery patients and normal controls. The trauma patients, the elective surgery patients, and the controls were all male, aged 18 to 36 years, in previous good health and with similar Injury Severity Scores. Only one of eight immunologic activities assayed distinguished between these groups of subjects. It was observed that the synthesis and secretion of immunoglobulins (Ig) in vitro by the circulating B cells of the trauma patients was markedly impaired when compared to Ig synthesis by B cells of the elective surgery patients or controls. Furthermore, it was demonstrated that the B cells, and not the T cells, Null cells, or monocytes, were defective in the trauma patients. The results indicate that diminished Ig synthesis and secretion by the circulating B cells of the trauma patients cannot be attributed to the surgery; rather, it appears that the defects in the B cells are a direct result of the trauma.

Adult↗
PubMed1987

A comparison of health promotion practices of general practitioners and residency trained family physicians.

Physicians who specialize in family medicine and general practice have the potential to assume a major role in helping patients change their health promotion practices. Little is known about the proportion of routine consultation time devoted to primary prevention counseling or the factors that influence the provision of this kind of patient education. A survey of General and Family Practitioners was conducted to determine the extent to which these physicians perform health promotion counseling as well as their perceptions regarding constraints affecting their efforts, confidence in their ability to change patient's behaviors, and the training required to enhance their efforts. Differences, with respect to their health promotion practices, between General and Family Practitioners, were also examined. One hundred and ninety-five physicians completed the survey for a response rate of 68%. When year of graduation from medical school was controlled there was little difference in the health promotion practices of General and Family Practitioners. This study suggests residency training in the specialty of family medicine does not provide residents with the knowledge, confidence and skills to perform health prevention counseling at a level different than that practiced by General Practitioners.

Clinical Competence↗
PubMed1986

Cells involved in the immune response. XXXII. Surgical extirpation of the spleen in the early memory period following primary i.v. immunization of the outbred rabbit results in a marked impairment of a subsequent immune response to the specific antigen: an immunological explanation for the overwhelming postsplenectomy syndrome.

Rabbits immunized intravenously(iv) with sheep erythrocytes(SRBC) (primary response) pass through a period which begins at about Day 35 postprimary immunization and extends to about Day 120 during which time all detectable spontaneous AFC (immediate PFC) and memory AFC(cells which generate PFC in culture) are detected only in the spleen. Prior to Day 30 postprimary iv immunization, large numbers of immediate PFC are detected in the circulation and the bone marrow as well as in the spleen. By Day 120 postprimary iv immunization, memory cells can be detected in significant numbers in the thymus and the popliteal lymph nodes (PLN) as well as in the spleen. The number of memory cells in the PLN and thymus increases over the course of the following 6 months. Rabbits splenectomized on Day 40 postprimary iv immunization and subjected to reimmunization iv with 10(9) SRBC 1, 5, or 8 months later were unable to give significant secondary immune responses. Only the thymus and PLN cells, cultured in vitro with the antigen(SRBC), 1, 5, or 8 months postprimary immunization, generated secondary immune(PFC) responses and these responses were feeble at best. The failure of the immunized rabbit to give a significant secondary immune response to SRBC if splenectomy was first carried out at a time postprimary iv immunization when all memory cells to the original antigen are sequestered only in the spleen (i.e., days 40 to 100) constitutes an animal model which provides a credible immunological explanation for the postsplenectomy syndrome which affects a minority of splenectomized individuals. These individuals, like the rabbits splenectomized on Day 40 postprimary immunization, lack the capacity to evoke a strong secondary immune response to particular infectious microorganisms and succumb in a few days with fulminant septicemia unless aggressive chemotherapy is instituted upon initial sign of infection.

Animals↗
PubMed1986

Cells involved in the immune response. XXXI. The role of the spleen in the primary and secondary immune responses in the normal adult outbred rabbit: the initial localization of memory cells to the spleen and their subsequent dissemination to the thymus and peripheral lymph nodes.

Normal adult outbred rabbits were immunized intravenously (iv) with sheep erythrocytes (SRBC). At varying times thereafter, the different lymphoid organs were investigated for spontaneous and culture-induced antibody secreting cells by the aqueous hemolytic plaque-forming cell (PFC) technique. During the phase of active antibody formation (Days 3 to 30), immediate PFC, indicative of spontaneous antibody synthesis and secretion, were detected principally in the spleen. In the early postimmune memory period (Days 30 to 90), memory cells capable of generating PFC following secondary immunization in in vitro culture with SRBC were detected only in the spleen. However, by 4 months postimmunization, memory cells were detected in the thymus and popliteal lymph node (PLN) as well as in the spleen. The number of memory cells in the thymus and PLN was significantly higher by 6 months postprimary iv immunization and was even further elevated by 9 months postprimary iv immunization. Following in vivo secondary immunization by the iv injection of SRBC 2 or 6 months postprimary immunization, immediate PFC were detected in large numbers in the spleen, the bone marrow, and the blood, marginally in the PLN and not at all in the thymus. Similar results were obtained at 9 months following primary immunization with SRBC with the exception that large numbers of immediate PFC were detected in the PLN following secondary iv immunization. Following culture of these lymphoid cells for 5 days in vitro with SRBC, the thymus and PLN cells, as well as the spleen cells, generated large numbers of PFC. Since immediate PFC were never detected among the freshly isolated thymus cells whereas thymic cell cultures 6 and 9 months postprimary iv immunization invariably generated large numbers of PFC following secondary immunization in vitro, the thymus memory cells would appear to be inaccessible to particulate antigen injected intravenously; they can only be detected following activation by the antigen in culture. The PFC generated by thymus memory cells (and spleen and PLN) were totally inhibited by the inclusion of sheep anti-rabbit IgG into the PFC assay. This finding demonstrates unequivocally that the plaques induced by thymus cells, just as the plaques induced by spleen and PLN cells, are antibody mediated and not false plaques. Therefore, the thymic PFC cells must be antibody-secreting B-memory cells since T cells do not synthesize or secrete immunoglobulins.

Animals↗
PubMed1986

Cells involved in the immune response. XXXIII. Antibody-forming cells in the popliteal lymph nodes in the immunized splenectomized rabbit following intravenous immunization and their subsequent dissemination to the thymus.

Rabbits were splenectomized (splx) and immunized intravenously (iv) with sheep erythrocytes (SRBC) 14 days later. At the height of the primary immune response on Day 8 postimmunization, significant numbers of plaque-forming cells (PFC), that is, antibody-forming cells (AFC) synthesizing and secreting antibodies, were detected in the popliteal lymph nodes (PLN) and lesser numbers were detected in the bone marrow and the circulation. No PFC were detected in any of the other lymphoid organs. Rabbits were sacrificed at 1, 2, 6, or 9 months post-primary iv immunization and cell cultures of the lymphoid organs were set up with the antigen, SRBC, to induce secondary immune responses in vitro. Only the PLN cells challenged with SRBC in vitro 1 month post-primary immunization generated PFC and only PLN and thymus cells generated PFC in vitro at the three other challenge periods, thus demonstrating the existence of memory cells in only these two lymphoid organs in the splx rabbits. Following in vivo secondary immunization iv with SRBC 2, 6, or 9 months post-primary iv immunization. PFC were consistently detected only in the PLN and the bone marrow and inconsistently in the circulation. No PFC were detected in the thymus or in any of the other lymphoid organs. Paradoxically, neither the bone marrow nor the circulating mononuclear cells of these rabbits generated PFC during in vitro culture with SRBC, whereas the thymus cells and the PLN cells generated many PFC in culture with SRBC. These results demonstrate that the thymus contains memory cells following primary immunization of the splx rabbit which are not accessible to particulate antigens injected intravenously, possibly due to a blood-thymus barrier to particulate antigen, and therefore cannot be activated in vivo into secondary antibody formation. The results also indicate that the AFC detected in the circulation and in the bone marrow following primary iv immunization, which do not generate PFC in antigen-stimulated cultures in vitro, are degenerating cells whereas the AFC in the PLN and thymus, which generate many PFC in antigen-stimulated cultures in vitro, constitute the noncirculating precursors of the long-lived memory cells in the splx rabbit. This role of the thymus and PLN as reservoirs for memory cells in the immunized splx rabbit is not influenced by nor is it a result of splx since the thymus and PLN have both been shown to be the major sources of memory cells, along with the spleen, in the immunized nonsplx rabbit.

Animals↗
PubMed1985

Pretreatment with chemotherapy in patients with advanced head and neck cancer.

Average survival for advanced head and neck cancer (AHNC) is 18 months. In an attempt to improve this we treated 29 AHNC patients between 1978-82 with two courses of chemotherapy. Chemotherapy consisted of cyclophosphamide, methotrexate, 5 fluorouracil and bleomycin; or bleomycin, cisplatinum and methotrexate. Chemotherapy was given prior to definitive therapy of radiotherapy or radiotherapy and surgery. All patients were stage 3 or 4. All patients were Eastern Co-operative Oncology Group status performance 0 or 1. Response to chemotherapy did not improve survival. Pretreatment with chemotherapy should be investigational until increased survival has been documented.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1979

Risk reduction in gastric operations for obesity.

Although nearly devoid of late complications, gastric operations for obesity have resulted in 4.7% early postoperative perforations. For patients over 39 years of age who perforated, the first 11 patients died and the last 9 survived. Perforations are equally common in upper stomach, anastomosis, and lower stomach. They have become more frequent with the 50 ml upper stomach volume and 12 mm stoma that are required to assure optimum weight control. Perforation is as common with gastroplasty as with gastric bypass. If it occurs, it is normally within the first ten postoperative days. Acute dilatation and rupture of the stomach can happen if all the nasogastric tube holes are in the jejunum after gastric bypass. Erosion of the stomach by the hard end of the nasogastric tube has occurred when the tube was positioned in the upper stomach. This paper is dedicated to the prevention of death by early recognition and aggressive management of perforation and by prevention of perforations through careful attention to the details of these operations and early postoperative care.

Adult↗