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Biomedical subjects

J Louw

Publications and source records attributed to J Louw.

At least 19 recordsLinked to original sources
PubMed2005

Islet cell response in the neonatal rat after exposure to a high-fat diet during pregnancy.

Although pancreatic beta-cells are capable of adapting their mass in response to insulin requirements, evidence has shown that a dietary insult could compromise this ability. Fetal malnutrition has been linked to low birth weight and the development of type 2 diabetes later in life, while reduced beta-cell mass has been reported in adult rats fed a high-fat diet (HFD). Reported here are the effects of exposure to a HFD, during different periods of gestation, on neonatal rat weight and beta- and alpha-cell development. The experimental groups were composed of neonatal offspring obtained from Wistar rats fed a high-fat (40% as energy) diet for either the first (HF1), second (HF2), or third (HF3) week, or all three (HF1-3) weeks of gestation. Neonatal weights and circulating glucose and insulin concentrations were measured on postnatal day 1, after which the pancreata were excised and processed for histological immunocytochemical examination and image analysis. HF1 and HF2 neonates were hypoglycemic, whereas HF1-3 neonates were hyperglycemic. Low birth weights were observed only in HF1 neonates. No significant differences were detected in the circulating insulin concentrations in the neonates, although beta-cell volume and numbers were reduced in HF1-3 neonates. beta-cell numbers also declined in HF1 and HF3 neonates. alpha-cell volume, number and size were, however, increased in HF1-3 neonates. alpha-cell size was also increased in HF1 and HF3 neonates. In neonates, exposure to a maternal HFD throughout gestation was found to have the most adverse effect on beta-cell development and resulted in hyperglycemia.

Animals↗
PubMed2002

Endometrial function in vervet monkeys (Cercopithecus aethiops): morphology, beta3 integrin and insulin-like growth factor binding protein-1 expression during the menstrual cycle and pregnancy in the normal and disrupted endometrium.

The expression of endometrial beta3 integrin and insulin-like growth factor binding protein-1 (IGFBP-1) was studied in cycling and pregnant vervet monkeys. There were clear changes of beta3 integrin expression during the menstrual cycle, with the strongest immunostaining observed on day 26. Moderate to strong expression was observed during pregnancy. The expression of IGFBP-1 during the menstrual cycle was weak but upregulated during pregnancy with moderate to strong staining. The administration of a single dose of onapristone at 10 mg/kg on days 17, 21 and 22 of the menstrual cycle, followed by a biopsy on days 22, 22 and 26, respectively, and during pregnancy (34-44 days menstrual age) 24 h before the biopsy, disrupted and desynchronized the endometrium. However, no effect on beta3 integrin expression could be observed and staining reflected the untreated patterns. The same applied to IGFBP-1 except that during pregnancy the expression of this protein was reduced or abolished. The results suggest that beta3 integrin is associated with endometrial receptivity in vervet monkeys and that IGFBP-1 plays an important role during pregnancy in this species. The administration of onapristone appeared to only influence IGFBP-1 expression. To our knowledge, this is the first time that these endometrial proteins have been investigated in vervet monkeys. This study should therefore contribute to improving our understanding of the reproductive function of this species.

Animals↗
PubMed2001

Brief occlusion of the main pancreatic duct rapidly initiates signals which lead to increased duct cell proliferation in the rat.

In the course of investigating the signals associated with pancreas regeneration, we have developed a method to initiate pancreatic duct cell proliferation by brief occlusion of the main pancreatic duct. The resulting duct cell proliferation, induced by temporary partial main duct occlusion, was compared to that induced by firmly tying a cellophane strip around the head of the pancreas for longer periods of time. Both methods stimulated a biphasic increase in duct cell proliferation, with proliferation maxima at 3 and 14 days post operation. The short duration of temporary main duct occlusion (60 s) that was needed to stimulate duct cell proliferation, and the similar duct cell proliferation profiles that were observed after both the temporary and the longer term main duct occlusion, led us to conclude that the signals which initiate proliferation occur rapidly at the beginning of each procedure.

Amylases↗
PubMed2001

The international union of psychological science and the politics of membership: psychological associations in South Africa and the German Democratic Republic.

This article examines the origins and the development of psychological associations in the German Democratic Republic and the Republic of South Africa and the ways membership in the International Union of Psychological Science (IUPsyS)--founded in 1951--figured in the process. The political regimes in these 2 countries had difficulties of their own in achieving a standing in the international community and, as a result, psychologists faced significant dilemmas in gaining legitimacy for the discipline. Membership in the IUPsyS served an important function in gaining legitimacy for the discipline in both countries, but it also contradicted legitimizing strategies that involved the countries' distinctive political and social structures. Membership in the IUPsyS was sufficiently important for psychologists to try to strike a compromise between different legitimation strategies.

Association↗
PubMed2000

Non-steroidal anti-inflammatory drug toxicity in the upper gastrointestinal tract.

Non-steroidal anti-inflammatory drug (NSAID) toxicity in the upper gastrointestinal tract is the most common serious drug-induced toxicity reported to drug regulatory authorities. In the last two decades, the rediscovery of H. pylori, development of potent ulcer-healing drugs and specific Cox-II inhibitors have opened new horizons in the management of NSAID toxicity. A Working Party composed of gastroenterologists and rheumatologists in the Asia-Pacific region met in Cairns, Australia, in 1999 to review the literature and develop appropriate guidelines. Recommendations were made based on the latest existing evidence. The importance of clinical events as study endpoints was emphasized. While differences exist between NSAIDs and aspirin, most studies have shown that advanced age, history of peptic ulcer disease, serious concomitant illnesses and coprescription of NSAID/aspirin with anticoagulants and steroids are high risk factors. These patients should be considered for prophylactic anti-ulcer therapy. Helicobacter pylori infection may aggravate the toxicity of NSAIDs and, in selected cases, should be treated before NSAID/aspirin is prescribed. Proton pump inhibitors and misoprostol are the most promising agents in preventing gastric and duodenal ulcers. When NSAID/aspirin needs to be continued in patients who develop an NSAID-related ulcer, proton pump inhibitors offer the best healing effect. With the discovery of cyclo-oxygenase isoforms (Cox-I and Cox-II), preferential and specific Cox-II inhibitors have been developed. While early clinical data have suggested promising antiinflammatory effects and improved safety profile in the gastrointestinal tract, several key issues on long-term safety remain unresolved. The use of potent anti-ulcer therapy, treatment of H. pylori infection and the development of Cox-II inhibitor will change the scenario of NSAID/aspirin-related gastrointestinal toxicity in the next millennium.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Culture and self in South Africa: individualism-collectivism predictions.

People from collectivist cultures may have more concrete and interdependent self-concepts than do people from individualist cultures (G. Hofstede, 1980). African cultures are considered collectivist (H. C. Triandis, 1989), but research on self-concept and culture has neglected this continent. The authors attempted a partial replication in an African context of cross-cultural findings on the abstract-concrete and independent-interdependent dimensions of self-construal (referred to as the abstract-specific and the autonomous-social dimensions, respectively, by E. Rhee, J. S. Uleman, H. K. Lee, & R. J. Roman, 1995). University students in South Africa took the 20 Statements Test (M. Kuhn & T. S. McPartland, 1954; Rhee et al.); home languages were rough indicators of cultural identity. The authors used 3 coding schemes to analyze the content of 78 protocols from African-language speakers and 77 protocols from English speakers. In accord with predictions from individualism-collectivism theory, the African-language speakers produced more interdependent and concrete self-descriptions than did the English speakers. Additional findings concerned the orthogonality of the 2 dimensions and the nature and assessment of the social self-concept.

Adult↗
PubMed1999

Deciding on cadaveric organ donation in Black African families.

This study explores factors that have affected the decision of Black African families to donate cadaveric organs. Semi-structured interviews were conducted with ten families living in greater Cape Town, South Africa. Addresses were obtained from records of the transplant co-ordinators at Groote Schuur Hospital. The data were analysed according to broad themes emerging from the interviews. The most important themes were the influence of violent, criminal deaths; the need for a longer period of consultation among family members: belief in the integrity of the ancestor's body; lack of understanding of brain death; and experiences of grief and loss.

Black or African American↗
PubMed1998

Development, differentiation, and regeneration potential of the Vervet monkey endocrine pancreas.

Using immunolabelling techniques, characterization of the Vervet monkey pancreas included a study of both its development and its structure and normal functioning in the adult. We found that PP and somatostatin occurred during development before glucagon. Insulin and all four pancreatic peptides occurred in one of the primordial buds prior to fusion. These finding call into question the suggested contribution of only PP cells by the ventral bud and non-PP cells by the dorsal bud. Co-localization of glucagon and PP was observed extensively with their relative expressions occurring in what appeared to be an organised non-random manner. Cells expressing both glucagon and PP persisted in the adult, together with many other combinations, suggesting an interesting plasticity of endocrine cell differentiation in the adult. Cellophane wrapping of the head of the Vervet monkey pancreas was shown to result in a noticeable increase in duct cell proliferation and endocrine cell volume but no increased replication of endocrine cells. Cells, immunoreactive for pancreatic peptides, were observed to bud from the ducts, suggesting a regeneration of endocrine cell tissue by neogenesis, although it is uncertain whether the duct epithelium contains the only stem cell source of new endocrine tissue. Hopefully, further investigations will elucidate a mechanism by which endocrine cell regenerative capacity can be stimulated in diabetics to overcome their absolute or relative deficiencies of insulin production.

Animals↗
PubMed1998

Foetal rat pancreatic transplantation: posttransplantation development of foetal pancreatic iso- and allografts and suppression of rejection with mycophenolate mofetil (MMF) and cyclosporine based immunesuppression.

Provided engraftment can be ensured, vascularization promoted, and ischaemic damage due to storage prevented, foetal pancreatic transplantation (FPT) has the potential to ameliorate the endocrine and metabolic disturbances in diabetic animal models including hyperglycaemia. In a syngeneic Wistar rat substrain (WAG) model (WAG --> WAG), FPT was capable of restoring normoglycaemia in diabetic rats rendered diabetic by streptozotocin (STZ). Posttransplantation growth and development of the foetal tissue was characterised by acinar atrophy, preservation of islet tissue, and development and proliferation of fat accumulations at the site of engraftment. B- and A-cell staining and distribution on ICC appeared normal after 12 months. Mycophenolate mofetil (MMF) together with cyclosporine (CSA) was selected to suppress rejection of foetal rat pancreatic allografts in a strong responder allogeneic model (WAG --> Sprague-Dawley). MMF, a novel immunosuppressive agent that selectively inhibits de novo purine synthesis, was administered in combination with subtherapeutic doses of CSA (2 mg/kg/day) to prevent rejection after allogeneic foetal rat pancreatic transplantation. Although CSA monotherapy in this model can partially suppress rejection, the combination of CSA and MMF results in significant inhibition of acute allograft rejection and mononuclear cellular (MNC) infiltration as assessed by sequential histology post-operatively. Although the follow-up period of allografts was restricted to 30 days of treatment, histology showed low graft infiltrate scores (1.2+) and preservation of islets and immunocytochemical staining. The results in this animal transplantation model confirm that sub-therapeutic doses of MMF and CSA therapy are effective in preventing acute rejection of foetal rat pancreatic allografts in the short-term, thus allowing preservation of vital endocrine components of the foetal pancreas such as islets.

Animals↗
PubMed1998

Induction of cell proliferation and differentiation in the pancreas of the adult Vervet monkey (Cercopithecus aethiops): preliminary results.

Cellophane wrapping of the adult Syrian golden hamster pancreas has been found to result in ductular cell proliferation leading to islet regeneration. Injection of cytosol from a cellophane-wrapped pancreas into normal or diabetic hamsters evoked a similar response. In view of the therapeutic potential of the active substance in this cytosol, it was decided to investigate whether a similar response could be achieved in a primate. In normal adult Vervet monkey (Cercopithecus aethiops) pancreas, proliferation is seen only rarely in islet cells and occasionally in duct and acinar cells. Immunohistochemical investigation of normal Vervet monkey pancreas (n = 4) and 14 days (n = 2) and 56 days (n = 1) after cellophane wrapping of the Vervet monkey pancreas revealed a slight increase in proliferation of islet and acinar cells and a larger increase in proliferation of duct cells and in total endocrine cell volume. The results suggest that there is a latent developmental capability in the adult primate pancreas.

Animals↗
PubMed1998

Making sense of kidney transplantation: a view from African recipients.

This study investigated the experiences of African patients who have undergone a kidney transplant within the past 10 yr, either from a live donor or from a cadaver. Little is known about kidney transplantation among African patients, in particular about psychological and social responses to the process. The study examined how these patients made (and still make) sense of the transplant experience, and hence attribute a particular subjective meaning to the factors and variables which have been at play during the course of the transplant. Semi-structured interviews were conducted with 14 African patients (8 women and 6 men), from the Renal Unit of Groote Schuur Hospital, Cape Town. The interviewees were selected from the records of the Unit. Several themes accounted for the frameworks of meaning that patients attributed to the transplant process. These are: religion and indigenous belief systems; the role of the extended family; patients' respective routes to the hospital; feelings about the transplant; and experiences in the hospital.

Adult↗
PubMed1997

Distribution of endocrine cells displaying immunoreactivity for one or more peptides in the pancreas of the adult vervet monkey (Cercopithecus aethiops).

BACKGROUND: Our previous studies on the Chacma baboon revealed that the most striking difference between islets of the ventral and dorsal regions of the pancreas was their content of A and pancreatic polypeptide (PP) cells with A cells predominating in the tail and PP cells in the uncinate and head. Cells displaying dual immunoreactivity for both glucagon and PP were also observed. The objective of this study was to establish baseline parameters of the adult Vervet monkey (Cercopithecus aethiops) pancreas so that it could be used as a primate model to investigate possible therapies for diabetes. METHODS: Vervet-monkey pancreas was divided into uncinate, head, and tail regions, and the tissue processed for immunolabelling for pancreatic peptides using avidin-biotin-peroxidase as marker. Dot-blotting and absorption controls for antibody specificity were included because of the shared amino acid sequences in pancreatic polypeptide (PP), neuropeptide Y (NPY), and peptide YY (PYY). Endocrine cell distributions and the percentages of each cell type per region were calculated for each monkey. RESULTS: A significant difference in the percentages of PP cells (P = 0.02) was observed between uncinate and tail regions, the distribution of NPY cells was similar to that of the PP cells, and all other distributions were similar to those reported in the literature for most animals studied. Cells displaying dual immunoreactivity for glucagon and PP or NPY, PYY and NPY, or PP, PP and somatostatin and glucagon and insulin were identified and mapped throughout the pancreas. Most co-localizations occurred in the uncinate region. Co-localization of glucagon and insulin has not, to our knowledge, been reported previously in the adult pancreas. CONCLUSIONS: Pancreatic endocrine cell distribution in the adult Vervet monkey was found to be very similar to most other animals studied. The occurrence of cells displaying dual immunoreactivity for a number of different combinations of pancreatic peptides suggests an interesting plasticity of endocrine cells even in the adult animal.

Animals↗
PubMed1997

The effect of diet on the Vervet monkey endocrine pancreas.

Vervet monkeys (Cercopithecus aethiops) used for pancreatic endocrine cell distribution studies were found to have been maintained on different diets. Although the effect of dietary changes on the exocrine pancreas has been described in several animals, little, apart from the effect of malnutrition, has been reported for the endocrine pancreas. Reported here are pancreatic endocrine cell distributions in monkeys on a standard diet (n = 3) compared with monkeys on an atherogenic diet (n = 3). Quantitation of immunolabelled pancreatic endocrine cell types revealed a significant 80% increase in A (glucagon) cell volume in monkeys on an atherogenic diet concomitant with a significant reduction in B (insulin) cell volume to approximately 60% of normal. This reflects a pattern of events that occurs in non-insulin dependent diabetes. An accompanying reduction in PP (pancreatic polypeptide) cell volumes supports our hypothesis that altering A and PP cell volumes could reflect differential gene expression in those cells in the adult in which glucagon and PP are co-localized.

Animals↗
PubMed1996

The non-human primate endocrine pancreas: development, regeneration potential and metaplasia.

An investigation into the development of the Vervet monkey endocrine pancreas revealed a sequence of occurrence of pancreatic peptides that differed from previous reports in mice, dog and human with PP and somatostatin occurring before glucagon and insulin. All four pancreatic peptides were identified, immunohistochemically, in only one of the pancreatic primordial buds, before fusion of the two buds to form the pancreas. This questions the hypothesis that the heterogeneous endocrine cell distribution seen in the adult pancreas is due to the contribution of only PP cells by the ventral bud and non-PP cells by the dorsal bud. Co-localization of glucagon and PP was observed extensively in the developing pancreas and the predominant expression of one over the other in an apparently organized non-random manner accounted for the glucagon- and PP-rich areas seen in the developing pancreas. A small number of cells immunoreactive to glucagon and PP were also observed in the adult. Reports of plasticity of differentiation of other pancreatic cells led us to investigate regeneration potential of the adult monkey pancreas. Partial obstruction of the Vervet monkey main pancreatic duct, by cellophane wrapping, resulted in duct cell proliferation and differentiation to form new endocrine tissue in a way that mimics normal organogenesis. Focal areas of hepatocytes were found in the regenerated pancreas of one monkey, illustrating further the latent developmental capabilities of adult pancreas cells. These findings could lead to interesting new therapies for pancreas and liver disease.

Animals↗
PubMed1995

HIV test counselling at a tertiary hospital.

A questionnaire was distributed to 64 of the 78 interns working at a teaching hospital in Cape Town in August 1992 to examine their attitudes and practice in respect of HIV test counselling. The questionnaire was completed by 61 interns. Thirteen per cent of those who responded counselled all patients, 49% counselled some patients and 38% counselled no patients. Thirty-four per cent stated that they felt that pre-test counselling was always necessary and 57% that post-test counselling was always necessary. The most frequently stated reasons for not counselling patients were language barriers, time constraints, feelings of incompetence on the part of the intern and the fact that the patient was too ill. It is recommended that standard counselling procedures be established in each ward and formal under- and postgraduate counselling training for medical students and interns be instituted.

Adult↗
PubMed1994

Collaboration: a critical viewpoint.

Post-graduate nursing education in Victoria, until recently, has been conducted as certificate level courses within hospital-based programs. These programs have traditionally drawn on the clinical experience, the supervision and the teaching provided by the resources within the hospital. This article describes the nature of a collaborative venture, involving regional hospitals and the university, and the challenges that emerged during the introduction of a post-graduate critical care course. Issues arising out of the course evaluation, which was conducted after the first year of the program elaborate aspects of the beginning nature of a collaborative venture. These issues include the different emphases and expectations of skills and knowledge, perceived as relevant to critical care practice. Some of the difficulties encountered by the students are raised. We employ the concepts of liberal and vocational/professional education to explore the ways in which present tensions signify what we have discovered to be an old pedagogical debate. The particular meanings we have as a profession when we speak about education are explored in the context of critical care education and collaborative practice.

Critical Care↗
PubMed1992

Illness behaviour in live-related and cadaver renal transplant recipients.

Illness behaviour was compared in 10 biologically live-related and 30 cadaver renal donor recipients in respect of their long-term psychological adjustment. The results indicated few long-term statistically significant differences postoperatively in illness behaviour between the two groups of patients, but a factor analysis revealed 8 items that were significantly related to illness behaviour associated with post-transplant psychological adjustment for all 40 transplantees studied. These were feelings of inadequacy; the renal graft being 'alien'; an inability to cope with the transplant; the disease resulting in the transplant being an external imposition beyond their control; responsibility for and acceptance of the transplant as a 'gain'; culpability for what has happened to them; anxious preoccupation with long-term prognosis; and dependence on others. Further analysis of these findings and their relevance for optimal patient management are discussed. Appropriate psychological support for these patients is important and, although long-term illness behaviour of biologically live-related and cadaver-related renal transplant recipients was found to be relatively similar, the various issues related to post-transplant illness behaviour in both groups of patients should be addressed in the provision of a psychonephrology service to a renal unit.

Adult↗