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Biomedical subjects

J Louw

Publications and source records attributed to J Louw.

33 records · Page 2Linked to original sources
PubMed1990

Do the pancreatic primordial buds in embryogenesis have the potential to produce all pancreatic endocrine cells?

A heterogeneity in the cellular composition of the endocrine pancreas, with a preponderance of pancreatic polypeptide cells in the lower head region, has been linked to the dual origin of the organ. The pancreas develops from a ventral bud thought to contain potential pancreatic polypeptide cells and a dorsal bud contributing the non pancreatic polypeptide cells. This does not explain, however, several anomalies including the results reported here of a homogenous distribution of non insulin cells in the foetal baboon whilst the adult pancreas exhibits a heterogenous distribution with the pancreatic polypeptide-rich area in the lower head of the pancreas. If this heterogeneity is associated with the dual origin of the pancreas, it would be expected to be more pronounced in the foetus. The anomalies could be explained if both primordial buds contained progenitor cells of all endocrine cell types which could be expressed to meet the requirements of the body at any particular time.

Animals↗
PubMed1990

Electron dense artefactual deposits in tissue sections: the role of ethanol, uranyl acetate and phosphate buffer.

The occurrence of electron dense deposits in sections of aldehyde-fixed tissue prepared for transmission electron microscopy has been attributed to a number of conflicting factors. In an attempt to clarify this, the precipitating effect of different combinations of phosphate or cacodylate buffer, glutaraldehyde, ethanol and uranyl acetate was investigated in test tubes. As a preliminary investigation the combination of phosphate buffer, ethanol and uranyl acetate was investigated in heart and kidney tissue fixed in glutaraldehyde with or without postosmication. The essential factors in the formation of electron dense deposits in these tissues appear to be phosphate buffer, ethanol, and uranyl acetate, although glutaraldehyde may contribute in some way. The nature and intensity of the deposits seem to vary with the sequence of combination of these factors. Osmium did not appear to be an essential factor in the reaction since deposits were observed in both osmicated and unosmicated tissue. To avoid such deposits, a postosmication distilled water wash for 20 to 30 min followed by en bloc staining with aqueous uranyl acetate is advised if phosphate buffer is used as a fixative vehicle or buffer wash after the primary fixative.

Animals↗
PubMed1989

Positive job planning.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Depression and self-report disclosure after live related donor and cadaver renal transplants.

Important psychological reactions are associated with renal transplantation in general. Differences in psychological adjustment between recipients of kidneys from cadavers (CRs) and recipients of kidneys from live related donors (LRRs), however, have been poorly researched. In this study 10 LRRs (mean age 35,7 years; mean number of years after transplant 4,5) were compared with 30 CRs (mean age 38,6 years; mean number of years after transplant 5,3). The prevalence of depression and self-disclosed stress-inducing factors which might have affected long-term psychological adjustment after the transplant were investigated. The psychological status of each patient was assessed by means of a clinical interview, a mental status examination, the Beck Depression Inventory and a self-report questionnaire. There were found to be no long-term statistically significant differences between the LRR and CR groups in terms of the prevalence of depression, although 20% of the patients overall were depressed to varying degrees. The CR group was more concerned about the psychological and personal characteristics of the donors and their families than the LRR group, who expressed concern about the future well-being of the donors. Many members of both groups expressed having experienced both fear of graft rejection, before and immediately after the transplant, and anxiety, which decreased with time. The therapeutic value of a positive psychological climate in the renal unit and of supportive family relationships was confirmed for both groups. In comparison with their existence while on dialysis, most of the patients, irrespective of donor type, ultimately enjoyed an enhanced quality of life.

Adult↗
PubMed1987

C-kinase activity in normal B cells treated with Staphylococcus aureus, Cowan strain I, and phorbol ester: response differences in a patient with prolymphocytic leukaemia.

Ca+2/phospholipid-dependent kinase (C-kinase) activity is intimately involved with the B-cell response after ligation of its mIg receptor. Here, we extend previous findings with anti-mIg by showing that polyclonal stimulation with Staphylococcus aureus, Cowan strain I (SAC), could also translocate C-kinase from the cytosol of intact, normal human B lymphocytes. This stimulus could not, however, induce redistribution of enzyme in a prolymphocytic leukaemia (PLL) B-cell population. Despite a normal density of mIg receptors on the latter cell type, PPL cells could not be stimulated to proliferate, express interleukin-2 (IL-2) receptors, and differentiate under the influence of SAC, even in the presence of exogenous IL-2. Normal B cells could respond appropriately to the same stimuli. PLL cells had a normal content of C-kinase activity and the enzyme could be translocated under the influence of the specific agonist, 12-0-tetradecanoyl phorbol-13-acetate (TPA). The same agent could induce cellular proliferation and differentiation in PLL cells, showing that its terminal C-kinase dependent pathways were intact. We conclude that the mIg receptor mechanism of this PLL population could not activate C-kinase appropriately.

Adult↗
PubMed1986

The epidemiology of inflammatory bowel disease in Cape Town 1980-1984.

Patients with inflammatory bowel disease diagnosed in the greater Cape Town area between the years 1980 and 1984 inclusive were studied to establish the incidence and presenting features of these diseases. Case details were obtained from the records of the Groote Schuur Hospital group and Tygerberg Hospital as well as from questionnaires completed by 97% of 731 medical practitioners in the area. There were 134 patients with Crohn's disease, 197 with ulcerative colitis and 16 with indeterminate colitis. The incidences of Crohn's disease in the coloured, white and black population groups were calculated to be 1.8, 2.6 and 0.3/100 000 per year respectively and those for ulcerative colitis 1.9, 5.0 and 0.6/100 000 respectively. Among Jews the incidence was higher for both Crohn's disease (10.4/100 000) and ulcerative colitis (17.0/100 000). Of patients with ulcerative colitis 35% had limited proctitis, 26% proctosigmoiditis, 12% left-sided disease and 27% total colitis. Of patients with Crohn's disease 27% had colonic involvement alone, 37% ileocolitis and 36% small-bowel involvement alone. The incidence of inflammatory bowel disease has increased in the greater Cape Town area over the last 10 years, while the pattern of disease has remained similar to that previously reported for this geographical area.

Adolescent↗
PubMed1986

Effect of oxygenated crystalloid cardioplegia on the functional and metabolic recovery of the isolated perfused rat heart.

The use of an oxygenated crystalloid cardioplegic solution to improve myocardial preservation during elective cardiac arrest was evaluated with the isolated perfused rat heart used as a model. Experiments were conducted at 4 degrees C and 20 degrees C. The oxygen tension of the nonoxygenated and oxygenated cardioplegic solutions averaged 117 and 440 mm Hg, respectively. At 4 degrees C, the adenosine triphosphate content of hearts subjected to 120 minutes of oxygenated cardioplegia was significantly higher than that of the nonoxygenated cardioplegia group. However, functional recovery during reperfusion was similar for both groups. At 20 degrees C, the myocardial adenosine triphosphate concentration decreased at a significantly faster rate during ischemia in the group receiving nonoxygenated cardioplegia compared with the oxygenated cardioplegia group. Hearts subjected to 180 minutes of ischemia with oxygenated cardioplegia had a normal ultrastructural appearance whereas hearts subjected to 120 minutes of nonoxygenated cardioplegia showed severe ischemic damage. Myocardial functional recovery in the group receiving oxygenated cardioplegia exceeded that of the group receiving nonoxygenated cardioplegia. The use of myocardial adenosine triphosphate concentration at the end of the ischemic period to predict subsequent cardiac output, peak systolic pressure, and total myocardial work showed significant positive correlations.

Adenosine Triphosphate↗
PubMed1981

Psychiatric disorders in a developing community as reflected by archival material.

We surveyed the clinical records kept at the outpatient psychiatric clinic at the Umtata Hospital, Transkei. The four commonest psychiatric disorders diagnosed at the clinic were schizophrenia, depression, epilepsy, and anxiety states. Other diagnoses included alcoholism, hysteria, confusional states and organic brain syndromes.

Adolescent↗
PubMedDate not supplied

Barrett's oesophagus: mucin composition, neuroendocrine cells, p53 protein, cellular proliferation and differentiation.

There is strong association of Barrett's oesophagus (BO) with adenocarcinoma. The sequence of events preceding malignancy appears to be reflux oesophagitis - ulceration - BO - dysplasia. One hundred and five biopsies of heterotopic columnar epithelium were stained for H&E, PAS/Alcian Blue and HID/Alcian Blue for the routine histology and neutral/acidic sialo- and sulphomucin staining. Other sections were silver impregnated by the Grimelius technique. Immunohistochemical techniques were applied for the assessment of the accumulation of p53 protein, "S" phase of the replication cell cycle using proliferating cell nuclear antigen (PCNA), marked for cell differentiation and proliferation using EGF and TGFa. 105 cases of heterotopic columnar epithelium consisted of 74 cases of BO, 25 junctional and 7 corpus mucosa. Dysplastic BO (n = 9) showed similar amount of sulphomucin and endocrine cell number when compared to non-dysplastic. PCNA study revealed a close similarity between dysplastic, indefinite for dysplasia and non-dysplastic, mucosal positive counts. Growth factors activity was significantly higher in dysplastic and indefinite than in non-dysplastic, but no such difference was found between dysplastic and indefinite for dysplasia BO. There was a significant concurrent p53 expression in dysplastic and indefinite for dysplasia BO. In conclusion, the practical utility of mucin stainings, endocrine cell count, assessment of cell proliferation and differentiation by PCNA, EGF and TGFa seems to be limited in differentiation of the dysplastic and indefinite for dysplasia BO. Altered expression of p53, particularly in combination with EGF and TGFa, may be useful in studying these lesions.

Adenocarcinoma↗
PubMedDate not supplied

The experience of family foster care in Malawi: a preliminary investigation.

This preliminary investigation into family foster care in Malawi set out to provide information on the Malawi government family foster care structure primarily through the qualitative experience of foster caregivers. A semistructured interview schedule was used to interview 24 foster parents, who were selected from a government family foster care register, in two regions of Malawi. The study revealed that cultural factors influenced various aspects of family foster care, ranging from the caregivers' decision to foster children to the caregivers' determination not to disclose to the children that they were fostered. Social and economic factors also played a role, particularly with regard to some shortcomings in service delivery.

Adaptation, Psychological↗