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Biomedical subjects

M C Williams

Publications and source records attributed to M C Williams.

At least 145 records · Page 8Linked to original sources
PubMed1983

Suspected vitamin E-selenium deficiency in two ostriches.

Paresis of the limbs of two 4-month-old ostriches fed a diet predominantly of crushed maize was investigated. Raised levels of serum aspartate transaminase and creatine kinase were demonstrated in both birds. The less severely affected ostrich recovered after a single intramuscular injection of a vitamin E-selenium preparation but the other died despite therapy. An autopsy of the latter revealed focal pale areas in the thigh muscle. Microscopically affected muscle fibres showed degeneration, necrosis and regenerative changes. Fibrinoid degeneration and necrosis of some arterioles was observed as well as varying degrees of interstitial fibrosis. The above findings suggest a diagnosis of vitamin E-selenium deficiency.

Animals↗
PubMed1982

Secretion of surfactant by primary cultures of alveolar type II cells isolated from rats.

Pulmonary surfactant conventionally is prepared from material obtained by endobronchial lavage. Although it has been assumed that the components of surfactant are secreted by alveolar type II cells, direct proof of this assumption has not been available. Furthermore, it is possible that the final material obtained by lavage has been modified after secretion or altered during the isolation procedure. It has been shown previously that type II cells, after 1 day in primary culture, secrete saturated phosphatidylcholine, one of the lipid components of surfactant. Because saturated phosphatidylcholine is not unique to surfactant and because type II cells in culture lose differentiated characteristics over the first several days in culture, it has not previously been established how closely the secretory products of cultures of type II cells resemble surfactant as obtained by endobronchial lavage. We therefore studied the morphologic, physical and chemical characteristics of the material that type II cells secrete under basal conditions and after stimulation with terbutaline or 12-O-tetradecanoyl-13-phorbol acetate. The secreted material resembled surfactant obtained by lavage; it was similar morphologically to the lamellar material and tubular myelin seen in the fluid-filled alveoli of fetal rats, it lowered surface tension to 5 mN per meter, and it contained the 72000 dalton apolipoprotein of surfactant (as measured by the 'rocket' immunoelectrophoresis technique). When cells were incubated for 22 h with [1-(14)C]acetate, the distribution of radioactivity in the secreted material was very similar to the phospholipid composition of rat surfactant. We conclude that the material secreted by alveolar type II cells after 1 day in primary culture is similar to surfactant obtained by endobronchial lavage.

Animals↗
PubMed1982

Depth, connectedness, and structural relevance in the object-superiority effect: line segments are harder to see in flatter patterns.

A briefly flashed line can be identified more accurately when it is part of certain types of pattern than in others (the 'object-superiority effects'). Three experiments were designed to investigate what aspects of these patterns determine the facilitatory effect of context. Subjects identified which of four line segments was present in various briefly flashed figures. Other subjects rated the figures for three-dimensionality, connectedness, and 'structural relevance' of the target line. Little relationship was found between connectedness ratings and accuracy in the identification task, but accuracy was highly correlated with mean depth rating (accounting for 95% of variance) and with mean structural-relevance rating (88%). Because of the high correlation (r = 0.98) between these two judgments in the present experiments, and confounding with other stimulus variables in previously published studies, the relative importance of these two global attributes cannot yet be determined definitively (though there was some evidence that for these patterns depth judgments were primary and structural-relevance judgments derivative). A reexamination of pertinent research suggests that comparisons between well-matched stimuli (as in the object-superiority effect) are likely to be more robust and informative than comparisons between lines alone and in context (the 'object-line effect').

Depth Perception↗
PubMed1982

Transepithelial transport by pulmonary alveolar type II cells in primary culture.

Fluid and electrolyte transport by epithelial cells in vitro can be recognized by the ability of cultured cells to form domes and by the electrical properties of monolayer cultures. Pulmonary alveolar epithelial cells are thought to be partially responsible for fluid movement in the fetal lung, but their role in electrolyte transport in the adult lung is not known. We isolated alveolar type II cells from adult rat lung and maintained them on plastic culture dishes alone, on plastic culture dishes coated with an extracellular matrix, and on collagen-coated Millipore filters. Numerous large domes were formed on culture dishes coated with the extracellular matrix; smaller domes were formed on uncoated plastic culture dishes. Sodium butyrate (3 mM) stimulated dome formation. Transmission electron microscopy showed that the epithelial cells had flattened but still retained lamellar inclusions and that the cells were polarized with microvilli on the apical surface facing the culture medium. The electrical properties of the monolayers maintained on collagen-coated Millipore filters were tested in two laboratories. The transepithelial potential differences were 0.7 +/- 0.1 mV (24 filters, seven experiments) and 1.3 +/- 0.1 mV (13 filters, two experiments) apical side negative, and the corresponding resistances were 217 +/- 11 ohm X cm2 and 233 +/- 12 ohm X cm2. Terbutaline (10 microM) produced a biphasic response with a transient decrease and then a sustained increase in potential difference. Amiloride (0.1 mM) completely abolished the potential difference when it was added to the apical side but not when it was added to the basal side, whereas 1 mM ouabain inhibited the potential difference more effectively from the basal side. Thus, type II cells form a polarized epithelium in culture, and these cells actively transport electrolytes in vitro.

Animals↗
PubMed1982

Problems in the measurement of putative serum immune complexes by the method of Beaumont.

A methodological investigation of the procedure used by Beaumont et al for measuring a "serum immune complex" precipitated by 25% ammonium sulfate and alleged to contain an ethynyl-estradiol binding immunoglobulin has found major problems with reproducibility and with the correlation of total protein as measured by the Lowry method and the IgG content as determined by a specific nephelometric procedure.

Antigen-Antibody Complex↗
PubMed1982

Ultrastructure of tubular myelin and lamellar bodies in fast-frozen adult rat lung.

In order to study the structure of membranes of tubular myelin and lamellar bodies (pulmonary surfactant), tissue from adult rat lung was prepared for freeze fracture by the rapid freezing method of Heuser et al. which requires no prior fixation or cryoprotection. Other tissues were freeze substituted and thin sectioned. A layer of tissue 50-100 mu thick was well preserved, but alveoli were partially collapsed. Freeze-fractured lamellar bodies were composed of tightly packed stacks of smooth lamellae about 100 A thick. Cross-fractures through tubular myelin exposed membranes organized into the square lattice described earlier. Fractures parallel to the longitudinal axis exposed particles arranged in rows which coincided with the corners. Membrane faces between the rows were smooth. These observations suggest (1) that in vivo the content of lamellar bodies is most likely arranged in layers, (2) that tubular myelin is present in tissues unexposed to fixatives or lipid solvents, (3) that smooth-surfaced lamellar body membranes become particulate when they form tubular myelin, and (4) that chemical fixation does not alter the general appearance of tubular myelin but it may affect lattice dimensions.

Animals↗
PubMed1981

Surface roughness and edge geometries in hemolysis with rotating disk flow.

Judging biocompatibility of materials with blood includes assessment of hemolysis resulting from flow in contact with those materials. Such hemolysis is influenced in part by the surface roughness and specific hydrodynamic features of the device used. Using a rotating-disk device, with polyethylene disks and human blood, it was shown that roughness under 4 microns has negligible effect and that hemolysis increases sharply for roughness above about 11 microns. Gross roughness (65 microns) causes qualitatively different hemolysis kinetics but not as severe hemolysis as extrapolated from low-roughness data. In the disk geometry, the corner is a key region which generates high hemolysis and thus minor alterations cause hemolytic variations which may tend to obscure materials influences. A series of corner-beveled polycarbonate disks were tested in comparison with the normal square corner and were found always to cause greater hemolysis. Tapering the bevel inward, so the taper angle was on the order of 2 degrees-4 degrees, reduced hemolysis relative to the 45 degree bevel but still was more hemolytic than the flat disk. Evidence suggests that glassy plastics can be machined with more reproducibility at the corners than plastics above their Tg such as polyethylene. General device design problems regarding hemolysis are discussed.

Biocompatible Materials↗
PubMed1981

Immunocytochemical localization and identification of the major surfactant protein in adult rat lung.

We investigated the cellular and subcellular sites of metabolism of the 72,000 dalton protein of pulmonary surfactant in order to provide insights into mechanisms of synthesis, intracellular assembly, and intraalveolar metabolism of this phospholipid-rich secretory product. Surfactant (approximately 90% lipid, 10% protein by weight) was purified by density gradient centrifugation of material obtained by lavaging rat lungs. The purified material was used to generate an antiserum from which a specific antibody was obtained by affinity chromatography. A horseradish peroxidase-labeled Fab was used to localize the antigen in rat lung. The antibody labeled the rough endoplasmic reticulum and Golgi apparatus of type II cells only. Some multivesicular bodies in type II cells were also labeled, but whether the antigen was present in lamellar bodies was uncertain. Phagosomes of alveolar macrophages were labeled as were similar inclusions in type I cells. Using indirect immunocytochemistry we determined that the labeling of alveolar cell surfaces does not represent the presence of a continuous layer of secreted surfactant. These results suggest that only the type II cell synthesizes surfactant protein and than mainly alveolar macrophages participate in its catabolism. The initial intracellular site of the association of protein with lipid may be multivesicular bodies as suggested previously by others.

Animals↗
PubMed1981

Spastic paresis in two littermate pups caused by Toxoplasma gondii.

The clinical and pathological findings in 2 sibling Bloodhound pups with spastic paresis of the pelvic limbs due to toxoplasmosis are described. Macropathology consisted of bilateral atrophy of the musculature of the affected limbs. Histopathology revealed meningo-encephalitis involving the cerebellum and medulla oblongata, diffuse meningomyelitis, radiculoneuritis of the lumbar spinal nerves and polymyositis and atrophy of skeletal muscle. Epizootological investigations failed to determine the source of the infection. Dissemination of the infection by a route other than the haematogenous pathway is considered and discussed.

Animals↗
PubMed1980

Metabolic properties and ultrastructure of alveolar type II cells isolated with elastase.

We used porcine pancreatic elastase to isolate type II cells from the lungs of rats; the yield and purity of the type II cells was better than that obtained by methods using trypsin. In 102 experiments we obtained 82 +/- 23 . 10(6) cells/rat, 68 +/- 11% (mean +/- S.D.) of which type II cells. This preparation of cells, when centrifuged over a discontinuous density gradient, yielded 25 +/- 10 . 10(6) cells/rat, 80 +/- 13% of which were type II cells (n = 102). The cells, after density gradient centrifugation, could be futher purified by centrifugal elutriation (94 +/- 3% type II cells, n = 22) or adherence in primary culture (94 +/- 2% type II cells, n = 34). Type II cells isolated with elastase are similar morphologically and biochemically to type II cells isolated from rats with trypsin. The preparations of cells appeared healthy by several different criteria: ultrastructure, exclusion of vital dye, lack of stimulation of oxygen consumption by exogenous sodium succinate, and linear rates of oxidation of [1-14C]palmitic acid and of incorporation of [1-14C]acetate into fatty acids. Type II cells consumed 75 +/- 20 nmol O2/10(6) cell per h, oxidized [1-14C]palmitic acid at a rate of 0.4 nmol/10(6) cells per h, and incorporated [1-14C]acetate into fatty acids at a rate of 7.5 nmol/10(6) cells per h.

Acetates↗
PubMed1980

Phospholipid composition and ultrastructure of A549 cells and other cultured pulmonary epithelial cells of presumed type II cell origin.

In order to assess the usefulness of A549, L-2, and AK-D cell lines as model systems for alveolar type II cells, we compared their phospholipid composition to that of fibroblasts grown under similar conditions. The percentage of disaturated phosphatidylcholine and phosphatidylglycerol, key phospholipids of purified surface-active material, was the same in epithelial cells and fibroblasts. When A549 cells were maintained in serum-free media for two days, ultrastructural examination showed an increase in cytoplasmic lamellar inclusions but there was no change in the percentage of disaturated phosphatidylcholine or phosphatidylglycerol. Because the lipid content of these cultured cells was very different from that of freshly isolated rat type II cells, we conclude that their suitability as model cell systems for type II cells is questionable.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1980

Chromatographic patterns of urinary ethynyl estrogen metabolites in various populations.

Radioactive mestranol (ME) and/or ethynylestradiol (EE) were administered to women in Nigeria, Sri Lanka, and the USA, and the types and patterns of radioactive urinary conjugates examined by Sephadex LH-20 chromatography. There are no differences in the total excretion of urinary radioactivity over 3 days. Consistent geographic differences appear to be present in the proportion of 3-, 17-, and 3,17-glucuronides. If confirmed on larger population samples, these observations may indicate significant geographic differences in the hepatic metabolism of ethynyl estrogens. High performance liquid chromatographic patterns of the urinary aglycone metabolites of ME and EE were examined in a number of women. The separation was accomplished on a Chromegaprep Diol column with a gradient of isopropanol in heptane. Ethynyl estrogen metabolism shows considerable individual variation. EE is usually the principal compound escreted following ME or EE administration. Unmetabolized ME is present in the ME profiles. The profiles of EE and ME are similar, with EE demonstrating a more complex pattern. Oxidative metabolism occurs chiefly at positions 2, 6 and 16 and is fairly extensive in the USA subjects. The Sri Lankan women generally show less of the oxidative products and the Nigerian group display a notable lack of oxidative metabolism. There is no difference in the metabolic patterns of long-term oral contraceptive users vs. non-users. Using silver sulfoethylcellulose column chromatography, from 14.1 to 34.7% of the excreted radiolabeled aglycones are non-ethynyl (i.e., either D-homo or de-ethynylated estrogens).

Adult↗
PubMed1980

Primary extramedullary plasmacytoma of the omentum associated with recurrent adenocarcinoma of the colon: first case report.

Extramedullary plasmacytomas are rare tumors, with 272 cases reported in the literature in English. Less than 10 per cent of these are located in the gastrointestinal tract. This report documents the first primary plasmacytoma of the omentum in association with a recurrent colonic adenocarcinoma. Extramedullary plasmacytoma, a B cell neoplasm, characteristically arises in areas containing lymphoid tissue. In our case the tumor most likely arose in a lymph node or nodes in the omental fat, with subsequent replacement of the entire greater omentum and involvement of the colonic serosa by direct extension. Although the extent and nature of the association between myeloma and carcinoma remain obscure, a review of the literature suggests that such association may occur more frequently than has been supposed. Further investigation would appear to be warranted.

Adenocarcinoma↗