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Biomedical subjects

M Webb

Publications and source records attributed to M Webb.

At least 37 records · Page 2Linked to original sources
PubMed1989

A monoclonal antibody, Py, distinguishes different classes of hippocampal neurons.

A monoclonal antibody, Py, was produced by immunizing mice with a glycoprotein fraction isolated from 3-week-old rat hippocampus. Py antibodies gave strong immunocytochemical staining of the perikarya and dendrites of large neurons in many areas of the rat brain, including the cerebral cortex, hippocampus, cerebellum, brain stem, and olfactory bulb. Immunoelectron microscopy showed the antigen to be predominantly intracellular, although its presence on the neuronal cell surface was not excluded. The antibody gave differential staining of adult hippocampal neurons, large pyramids of field CA3 being strongly immunoreactive, while CA1 pyramids and the dentate granule cells were unstained. Some interneurons were positive in each of the hippocampal fields. In developing hippocampus, the Py antigen appeared by the middle of the first postnatal week, and the adult pattern of staining was achieved by the end of the second week. Immunoblotting showed the antigen to have a relative mobility of 146 kDa with an additional faint band at 166 kDa. Differential Py staining of neurons was seen in dissociated cultures of embryonic hippocampus and in subdissected hippocampal fragments transplanted into adult host brains. This antibody can therefore be used for identification of hippocampal neurons that have been removed from their normal anatomical context.

Animals↗
PubMed1987

Metallothionein in regeneration, reproduction and development.

The presence of metallothionein in high concentrations in the livers of foetuses and/or newborn of all mammalian species thus far investigated is well-established, explanations of why it is there and what it does are hypothetical. This paper attempts to distinguish between fact and fiction and to evaluate critically the evidence for and against the various functional roles that have been proposed for metallothionein in liver regeneration and in mammalian reproduction and development.

Animals↗
PubMed1987

Huntington's disease: correlations of mental status with chorea.

We have studied 10 Huntington's disease (HD) outpatients to investigate the relationship between chorea and the psychiatric manifestations of this disease. We used neuropsychological tests sensitive to memory and diffuse cerebral dysfunction and a new, simple, objective test of chorea to study the relationship between chorea and dementia. Using SADS/DSM-III diagnoses, we replicated previous findings of the high prevalence of psychiatric disorders associated with HD. A new finding in this study was the strong relationship between the severity of chorea and that of dementia, particularly regarding memory loss. Implications of this finding are discussed in light of the neuroanatomy of the basal ganglia and frontal lobes.

Adult↗
PubMed1987

Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--IV. Mechanisms of intestinal copper accumulation.

Copper-67, administered either parenterally or via the maternal milk, accumulates principally in the intestine and liver of the 6-day-old pup. Most of the 67Cu in the soluble fraction of the intestine is associated with the heterogeneous Cu-complex, which is located predominantly in the ileum. The rates of uptake and loss of 67Cu in the liver and intestine indicate that enterohepatic circulation of Cu in the neonate is appreciable. Whilst the concentration of Cu in the bile of the 13-day-old pup is high (16-fold greater than that in the adult male rat), translocation of Cu from both the liver and duodenum to the ileum probably occurs via the blood, rather than by the reabsorption of biliary Cu. Although the Cu-complex normally seems to be retained within the distal intestine until the enterocytes are desquamated, Cu in this form is utilized when the Cu-intake of the neonate is restricted.

Animals↗
PubMed1986

Steroid receptor activation: the glucocorticoid receptor as a model system.

The glucocorticoid receptor has been used as a model for steroid receptor activation. Because of recent evidence for the essentially nuclear location of the unoccupied receptors of 1,25-dihydroxycholecalciferol and 17 beta-estradiol, the significance of the activation mechanism converting unactivated receptor complexes to DNA-binding forms is unclear for some receptors. Up to now the weight of evidence favors a cytoplasmic location of the unactivated glucocorticoid receptor. In this article we describe studies on the nature of the activation mechanism and of regulatory factors.

Animals↗
PubMed1986

Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--III. Effects of closure.

The ileum of suckling rats contains a high level of copper, most of which is concentrated within cytoplasmic vesicles of the enterocytes. Intestinal closure, 20-21 days after birth, results in the replacement of enterocytes by cells devoid of these vesicles and there is a concomitant fall in the level of copper in the ileum. Administration of cortisone acetate (0.5 mg/g body wt) to 5-day-old rats results in premature loss of copper-laden ileal enterocytes and an 80-90% decrease in the ileal copper concentration. The loss of copper is mainly from the soluble fraction of the tissue and is proportionally greater from the high molecular weight-protein fraction rather than from the copper complex.

Animals↗
PubMed1986

Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--I. Distribution and binding.

The distribution of the heterogeneous copper (Cu)-complex in the intestine of the neonatal rat parallels that of total Cu and is maximal in the ileum. In the ileum the total Cu concentration exceeds 400 micrograms/g wet wt at 14 days of age and then falls to about 20 micrograms/g wet wt in the 20-day-old pup. The apoproteins (apopeptides) of the Cu-complex, which are absent from the late-foetal intestine, vary in number and proportion with postnatal age and nutritional status.

Aging↗
PubMed1986

Intestinal uptake and retention of copper in the suckling rat, Rattus rattus--II. Copper accumulation in the ileum and distal jejunum.

High concentrations of copper were demonstrated histochemically in the enterocytes lining the ileum and distal jejunum of suckling rats. Copper was not detected in cells from the duodenum or proximal jejunum of these rats or from any region of the small intestine of rats in which "closure" had taken place. X-Ray microanalysis demonstrated copper, in equi-atomic association with sulphur, within discrete vesicles in the supranuclear cytoplasm of the enterocytes. Despite the high concentrations of these two elements no biochemical evidence was found for the presence of significant amounts of copper-binding metallothionein. The highest concentrations of copper (226 +/- 48 mg atoms/kg dry wt: +/- SD) were found in vesicles adjacent to the nucleus, which did not accumulate particulate tracers, or calcium from the lumen of the intestine. These vesicles probably result from the coalescence of Golgi-derived primary lysosomes followed by fusion with endocytic vacuoles. They may provide a mechanism of copper excretion from the neonatal rat.

Acid Phosphatase↗
PubMed1985

Non-spindle microtubule organizing centers in metaphase II-arrested mouse oocytes.

A human autoantiserum (5051) directed against pericentriolar material (PCM) was used to study the distribution of microtubule-organizing centers (MTOCs) in the oocyte and during the first cell cycle of mouse development. In oocytes, the PCM was found not only at the poles of the barrel-shaped metaphase II spindle but also at many discrete loci around the cytoplasm near the cell cortex. The spindle poles were also composed of several PCM foci. In metaphase-arrested eggs only the PCM foci located near the chromosomes acted as MTOCs. However, after reduction of the critical concentration for tubulin polymerization by taxol, the cytoplasmic PCM foci were also found to be associated with nucleation of microtubules. After fertilization the cortical PCM foci remained in a peripheral position until the end of the S phase, when they appeared to migrate centrally towards the pronuclei. At prometaphase of the first mitotic division, numerous MTOCs were found around the two sets of chromosomes; these MTOCs then aligned to form two bands on either side of the metaphase plate of the first mitosis.

Alkaloids↗
PubMed1979

Complex formation between selenium and methylmercury.

Methylmercury, after incubation at 3k7 degrees C and pH 7.0 with selenite in the presence of rat erythrocytes, can be extracted into benzene as an unstable 2 : 1 complex with selenium. The same complex, possibly bis-methylmercury selenide, is formed when methylmercury is treated with hydrogen selenide at pH 7.0 in the absence of erythrocytes.

Animals↗