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Biomedical subjects

C J Muller

Publications and source records attributed to C J Muller.

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↗
PubMed2000

An immunocytochemical profile of the endocrine pancreas using an occlusive duct ligation model.

CONTEXT: Ligation of the pancreatic duct, distally to its confluence into the bile duct has been shown to induce endocrine tissue regeneration. The surplus endocrine tissue formed is presumed to be able to replace pathologically and/or experimentally compromised tissue. OBJECTIVE: This is a quantitative study on the histology of duct ligated pancreas employing immunocytochemistry and computerised morphometry. INTERVENTIONS: Pancreatic duct ligation was performed on 25 groups of six normal Sprague-Dawley rats. Experimental animals were sacrificed at 12-hour intervals from day one to ten post-duct ligation and every 24 hours thereafter to day 14, the pancreas removed, fixed and processed. Six consecutive 3-6 micron serial sections were cut on a rotary hand microtome, floated onto 3-aminopropyl-trimethoxysilan coated slides and alternatively immunocytochemically stained for insulin, glucagon, pancreatic polypeptide and somatostatin. RESULTS: Pancreas transformation between days 1/2 and 3 1/2 was characterised by acinar deletion and the appearance of immunoreactive cells for the primary endocrine hormones. Transdifferentiation of existing endocrine tissue saw islet insulin core cells replaced by pancreatic polypeptide- and somatostatin positive cells, glucagon deletion and random appearance of all endocrine cell types within the inter-islet interstitium by day 3 1/2. Days 4 to 14 were characterised by cellular migration and islet reconstruction. CONCLUSIONS: To date our laboratory has investigated transplantation of foetal tissue beneath the renal capsule in syngeneic, isogeneic and allogeneic normal and diabetic rats. As pancreatic duct ligation induces the development of surplus endocrine tissue our next step would be to investigate the use of ligated pancreas as a replacement for foetal tissue.

Animals↗
PubMed1996

An ultrastructural study of the development of the chicken perineurial sheath.

Three phases of perineurial development were recognised in the chicken sciatic nerve: (1) an early primitive phase during which the embryonic perineurium appeared to organise from the surrounding mesenchyme; (2) an intermediate phase of differentiation with the formation of a multilayered cellular network around the Schwann cell-axon complexes, and (3) a final phase of maturation during which the perineurial sheath showed features correlating with those of a functional barrier. Our observations support a mesenchymal origin for the perineurium rather than a schwannian derivation with clear separation of these 2 cell populations during all stages of development. Although the embryonic perineurial cells initially showed a fibroblast-like appearance, distinctive features of perineurial differentiation were present as early as 5 1/2 days (d) (Hamburger & Hamilton stage 28 embryo). Perineurial differentiation appeared to be intimately associated with developmental events in the Schwann cell-axon complexes, particularly during the period of most active Schwann cell proliferation. It is proposed that factors released by the Schwann cell-axon complexes during this period may be responsible for perineurial differentiation and organisation from the surrounding mesenchyme. The presence of endoneurial blood vessels following the appearance of perineurial basal lamina at 17 d (stage 43) suggested the emergence of a perineurial barrier. A perineurial architecture and cytological fine structure comparable to that of the adult animal was, however, only observed in the 10 d-old-chick.

Animals↗
PubMed1991

Rural anaesthetic practices in the western Cape.

The findings of specialist anaesthetists on visits to rural towns in the western Cape over 6 years are reported. The importance of academic units communicating with general practitioners, nursing staff and hospital authorities in their own working environment is emphasised. Hospital anaesthetic facilities and general practice anaesthetic methods are discussed and recommendations made and, in addition, common problems that could improve anaesthesia in general practice are summarised.

Anesthesia↗
PubMed1984

Accuracy or inaccuracy of spleen mass measurements from radionuclide images.

In a retrospective study, scintigraphic spleen size was compared with actual spleen weight. Using the formula W = pi/7 h (h2 + 3ab), the normal weight was calculated too large and splenic enlargement was calculated too small. Other scintigraphic parameters seem to be just as unreliable. We suggest to judge scintigraphic spleen mass as normal and only be enlarged in obvious situations.

Adult↗
PubMed1983

In-111 leukocyte scanning and partial functional asplenia in a patient with Sézary syndrome.

Functional asplenia is described in the case report of an 80-year-old woman who was admitted with Sézary syndrome. The spleen could not be visualized by a Tc-99m tin colloid (SnC) liver and spleen scan, but was visualized by a Tc-99m sulfur colloid (SC) scan, suggesting a different mechanism in accumulation of SnC and SC in the spleen. In-111 oxine labeled Sézary cells could be found in the spleen, bone marrow, and lymph nodes.

Aged↗
PubMed1978

Radiology and the law in South Africa.

In terms of regulations gazetted in 1973, the Department of Health has control of the practice of medical radiology in South Africa. The regulations and the rules of the South African Medical and Dental Council that apply to radiology are discussed, and the legal position of workers is noted.

Employment↗