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Biomedical subjects

M Waters

Publications and source records attributed to M Waters.

44 records · Page 3Linked to original sources
PubMed1979

Ultrastructure and x-ray microanalysis of macrophages exposed to cadmium chloride.

Macrophages have a direct role in the inflammatory response to cadmium exposure. Cadmium is not only an important air pollutant, but is also one component of cigarette smoke. To study the effects of soluble cadmium on macrophages, two model systems were chosen:rabbit alveolar macrophages (RAMs) obtained by pulmonary lavage and peritoneal macrophages elicited by intraperitoneal injections of 10(7) viable M. bovis, bacillus Calmette Guérin (BCG MACs). Macrophages were maintained in standard tissue culture medium from 4 to 30 hours with concentrations of cadmium chloride (CdCl2) ranging from 0 to 1.0 mM. Attached macrophages and RAMs in suspension were studied by conventional transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive x-ray microanalysis (EDX). In addition to routine techniques for TEM and SEM, preparatory procedures included snap freezing in liquid propane, and either cryoultramicrotomy or freeze-substitution with 1% osmium tetroxide in acetone. By TEM many macrophages exhibited laminated nuclear inclusions at doses as low as 0.05 mM CdCl2) (at 20 hrs) and as early as 4 hrs (at 1.0 mM CdCl2). Sections of cells fixed by freezing exhibited the same nuclear inclusions as well as mitochondrial densities that were not visible with any other preparative technique. Cadmium was demonstrated in the nuclear inclusions and mitochondrial densities by EDX in snap frozen cells. Lesser amounts of cadmium were also detected diffusely in treated cell cytoplasm and nuclei. Cadmium was only detected by EDX in cells fixed by freezing. These studies document the localization of Cd in nuclear inclusions and mitochondria providing morphological support for the biochemical findings of other laboratories. In addition, the value of fixation by freezing over conventional chemical fixation is illustrated.

Animals↗
PubMed1975

Fulminant meningococcal septicaemia. A hospital experience.

In the first 5 months of 1975, 12 cases of meningococcal septicaemia were seen at a children's hospital where in previous years the condition was seen only sporadically. 3 of these children were dead on admission, 5 died shortly after admission, and 4 responded to treatment. Neisseria meningitidis was recovered from cerebrospinal fluid or blood or both in all cases, and the clinical illness was characterised by fever, prostration, and cutaneous purpura of abrupt onset. There were no significant previous illnesses, no recognisable prodromata, and, bacteriology apart, no pattern of laboratory results. There was a suggestion of centre-city clustering in the home background, although 2 of the patients came from rural areas. At necropsy gross adrenal haemorrhage was found in 6 of the 8 fatal cases, and upper gastrointestinal bleeds in the 5 deaths which were not sudden.

Autopsy↗
PubMedDate not supplied

Up-regulation of growth hormone receptor immunoreactivity in human melanoma.

Growth hormone (GH) exerts its regulatory functions in controlling metabolism, balanced growth and differentiated cell expression by acting on specific receptors, which trigger a phosphorylation cascade resulting in the modulation of numerous signalling pathways, and dictate gene expression. Immunohistochemical techniques were used to demonstrate the presence of growth hormone receptors in 126 formalin-fixed, paraffin-embedded melanocytic tumours comprising melanocytic naevi, superficial spreading melanoma, nodular melanoma, lentigo maligna melanoma and metastatic melanomas. The relative proportion of positive cells and intensity of staining was higher in neoplastic cells, compared to normal cutaneous cells. Of the 76 cases of common melanocytic naevi (CMN) studies, 46 were weakly reactive with MAb 263. Heterogeneity of immunoreactivity was found in primary melanoma lesions with a variable range of positive cells. Of 37 cases studied, 34 were moderately to strongly positive. Immunoreactivity showed subcellular localization of the GH-receptor in cell membranes, was predominantly cytoplasmic, but strong nuclear immunoreaction was also apparent in many instances. The nuclear localization of immunoreactivity is the result of nuclear GH-receptor/binding protein, identically to the cytosolic and plasma growth hormone binding protein. Intense immuno-reactivity was also observed in the cellular Golgi area of established cell lines and cultured tissue-derived cells in exponential growth phase, indicating cells are capable of GH-receptor synthesis. In the primary lesions, dermal tumour cells tended to be more immunoreactive relative to those seen in the dermal region. Metastatic lesions in various organs also expressed growth hormone receptors in secondary tumour cells and all of the metastatic cases were positive. The expression of GH-receptors in human melanoma cells means that these cells are directly responsive to GH action and that GH may stimulate local production of IGF-I, which then acts in an autocrine mechanism.

Animals↗
PubMedDate not supplied

Properties of an experimental mouthguard material.

PURPOSE: The purpose of the present study was to evaluate some important mechanical properties of an experimental silicone material (PM1) to assess its potential as a mouthguard material. MATERIALS AND METHODS: The hardness, tear strength, tensile properties, and energy absorption properties of the silicone material were determined and compared with those of 2 commercially available materials (Bioplast, a polyvinylacetate polyethylene, and Polyshield, a silicone). RESULTS: Bioplast was significantly harder than Polyshield and PM1. Polyshield was significantly harder than PM1. Bioplast had a significantly higher tear strength than both Polyshield and PM1. The tensile strength of Bioplast was significantly greater than that of Polyshield and PM1. PM1 had a significantly higher tensile strength than Polyshield. Bioplast had a significantly lower energy absorption capacity at 500 N than both Polyshield and PM1, with PM1 having a significantly higher value than Polyshield. At 1,000 and 1,500 N, Bioplast had a significantly higher energy absorption than both Polyshield and PM1. CONCLUSION: It was concluded that PM1 showed better energy absorption properties than Polyshield and better energy absorption properties than Bioplast at lower impact forces. PM1 was softer and had better tear and tensile properties than Polyshield. The results of the present study suggest that the new material has a good potential for use as a mouthguard material.

Analysis of Variance↗