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Biomedical subjects

M C Williams

Publications and source records attributed to M C Williams.

At least 127 records · Page 7Linked to original sources
PubMed1985

Identification of rat alveolar type II epithelial cells with a tannic acid and polychrome stain.

Alveolar type II epithelial cells are identified by the presence of characteristic lamellar inclusions visualized by transmission electron microscopy. We developed a tannic acid and polychrome stain that can visualize these intracellular inclusions in rat alveolar type II cells by light microscopy and that can be used for autoradiography. This method of staining and fixation provides more cellular detail than other methods that use light microscopy.

Animals↗
PubMed1985

Effects of blood storage on rheology and damage in low-stress shear flow.

Data are presented on the rheological and hemolytic behavior of whole human blood as it ages while stored at 4 degrees C (as in blood banking practice) up to 26 days. The viscometric properties of steady shear viscosity eta and oscillatory (complex) viscosity eta * = eta' - i eta" reported over ranges of shear rate gamma and radian frequency omega of 33 less than gamma less than 4130 s-1 and 1.5 less than omega less than 48 s -1; data on autologous plasma are given for reference. The Cox-Merz relation, eta (gamma) = [eta *(omega)] omega = gamma, is found to be a good approximation, with eta greater than or equal to [eta *], over the range studied. Release of hemoglobin (Hgb) and lactate dehydrogenase (LDH) into the plasma during shearing is tracked as a function of time for 30 min, and its sensitivity to gamma magnitude is measured. Bloods from four different donors are studied, with primary attention given to one (SSR). For all bloods, the release of both Hgb and LDH increases with storage age, but differences in such aging characteristics between different bloods can be substantial (even when rheological properties are identical). A post-shear incubation at 4 degrees C for one day shows no enhancement of plasma Hgb and LDH levels beyond those expected from normal aging after the shearing experience, demonstrating the absence of significant delayed-action effects as a consequence of shearing trauma.

Blood Preservation↗
PubMed1985

Mortality of a white rhinoceros (Ceratotherium simum) suspected to be associated with the blue-green alga Microcystis aeruginosa.

Three of four white rhinoceroses died within 3 months of introduction into a game reserve. Post-mortem examination of one of the animals revealed marked hepatomegaly with haemorrhage and severe necrosis of the liver as well as numerous ecchymoses and petechiae in the subcutaneous tissue and subserosa of the thorax, abdomen and diaphragm. Histologically, severe hepatic necrosis was the most significant finding. Algae recovered from the dam from which the animals drank were identified as Microcystis aeruginosa. A diagnosis of suspected Microcystis poisoning was made.

Animals↗
PubMed1984

Protein composition of rabbit alveolar surfactant subfractions.

The goal of this investigation was to characterize the proteins in subfractions of alveolar surfactant obtained by lung lavage and separated by differential centrifugation. It was previously demonstrated that the material in the more sedimentable fraction, which was enriched in tubular-myelin and was surface-active may be a precursor to the less sedimentable, vesicular, inactive material [1]. Separation of the proteins by polyacrylamide gel electrophoresis showed that the more sedimentable subfractions and rabbit surfactant isolated by conventional methods contained proteins with molecular weights comparable to those previously reported for alveolar surface active material (approximately 36 000 and 10 000). The less sedimentable subfractions contained less of these proteins. Immunoblots with anti-dog surfactant apoprotein antibodies, which cross-react with rabbit proteins, supported these observations. Immunoblots also showed that all of the subfractions contained serum proteins and secretory IgA, with the less sedimentable subfractions containing more secretory IgA. These results suggested that changes in protein composition may accompany functional changes in surfactant in the alveoli.

Animals↗
PubMed1984

Detection of an abnormal lipoprotein in a large colony of pedigreed baboons using high-performance gel exclusion chromatography.

High-performance gel exclusion chromatography was used to detect an abnormal lipoprotein in a large colony of baboons. Serum obtained from fasting baboons was adjusted to density 1.21 g/ml and ultracentrifuged to obtain lipoproteins. A small fraction (equivalent to 50 microliter serum) was separated using a gel filtration column (TSK 4000 SW) or a combination of TSK 4000 PW and TSK 3000 PW columns. The unusual lipoprotein was detected either as a distinct peak between low- and high-density lipoproteins or as a distinct shoulder to the high-density lipoprotein peak. In some baboons the unusual lipoprotein was present on both chow and atherogenic diet, but in most cases it was induced by feeding an atherogenic diet.

Animals↗
PubMed1984

Role of calcium ions the structure and function of pulmonary surfactant.

Pulmonary surfactant isolated by centrifugation in buffers containing ions contains at least three different morphologic structures. The presence of one of these, tubular myelin, is dependent on calcium ions, since chelation of the calcium ions causes disruption of this structure. Addition of EDTA also decreases the ability of the surfactant to absorb rapidly to air-water interfaces and lower surface tension. Titration with calcium ions (2.5 or 5 mM) restores rapid surface adsorption and restores the tubular myelin structural forms. Magnesium ions cannot substitute for calcium ions in these processes. The reversibility of structure and function induced by calcium ions and EDTA is also accompanied by reversible isopycnic density shifts probably related to aggregation and disaggregation of the lipid-protein complex with calcium ions and EDTA, respectively.

Animals↗
PubMed1984

The effect of perceived depth and connectedness on metacontrast functions.

When a barely visible target line is briefly flashed within a context of other lines, it is identified more accurately if the lines form a pattern that is perceived as a unified, three-dimensional object. This finding has been called the object-superiority effect [Weisstein and Harris, Science, 186, 752-755 (1974)]. The present study concerns what happens when different context patterns are presented at a variable delay after the target line. The resulting temporal functions of identification accuracy against delay of context pattern differ systematically with two perceptual variables: three-dimensionality and connectedness. The results suggest that differences in the temporal functions correspond to differences in visual response properties elicited by different perceptions of three-dimensionality and connectedness.

Depth Perception↗
PubMed1984

Endocytosis in alveolar type II cells: effect of charge and size of tracers.

The type II cell of the alveolar epithelium of adult rats has been studied by electron microscopy to determine its ability to endocytose electron-dense tracers of differing molecular charge and size. The tracers studied were native (anionic) ferritin, cationic ferritin, 70-kilodalton dextran, and colloidal carbon. Alveolar macrophages ingested all tracers in large amounts, while type II cells took up significant amounts of cationic ferritin only. This tracer was observed, in sequence, within small pinocytic vesicles, large electron-lucent multivesicular bodies, small electron-dense multivesicular bodies, and, by 30 min after instillation, within the nonlamellar matrix of lamellar bodies. By 2 hr all lamellar bodies in any labeled cell contained cationic ferritin. Cationic ferritin also appeared to be transported from alveoli to interstitium by vesicles of type II, but not type I, cells. Native ferritin and dextran were observed in the same organelles as cationic ferritin but in much smaller amounts; colloidal carbon was not taken up by type II cells. These tracers were not observed in the alveolar interstitium. Type II cells therefore appear to internalize preferentially the tracer that binds to the cell membrane. Once within the cell, the tracer may enter a pathway that terminates in a lamellar body or, in the case of cationic ferritin, may be ferried across the cell.

Animals↗
PubMed1984

Uptake of lectins by pulmonary alveolar type II cells: subsequent deposition into lamellar bodies.

Type II cells of the alveolar epithelium of adult rats have been shown to internalize the ferritin-labeled lectin from Maclura pomifera (MPA-F). This alpha-galactose-binding molecule binds specifically to the apical plasma membrane of the cells. Once within the cell the lectin is cycled from pinocytic vesicles, to multivesicular bodies of two types, and finally to lamellar bodies, the storage granules of surfactant. Those multivesicular bodies that first contain MPA-F lack detectable lysosomal enzymes, while those labeled later are reactive. For 30-60 min, uptake of MPA-F is blocked by adding methyl alpha-D-galactoside to the instillate. Lectins that have no or limited binding to type II cells are taken up in amounts similar to fluid phase markers. These observations indicate that type II cells can take up substances from alveoli by the process of adsorptive endocytosis and deposit the ingested material into lamellar bodies.

Animals↗
PubMed1984

Role of apoprotein and calcium ions in surfactant function.

Pulmonary surfactant isolated in the presence of calcium ions contains substantial amounts of the morphologic structure, tubular myelin. Chelation of these calcium ions results in disruption of this structure and attendant loss of surface adsorption. Reassembly studies indicate that ability of the lipids to rapidly form surface films is dependent on the presence of a specific surfactant protein in addition to the calcium ions. The formation of this surface-active complex (apoprotein-lipid-calcium ions) is accompanied by aggregation of the lipid. This increase in aggregation may have important implications in the mechanism of surfactant function.

Adsorption↗
PubMed1984

Toxicity of seeds of three Aesculus spp to chicks and hamsters.

Seeds of horse chestnut (Aesculus hippocastanum), Ohio buckeye (A glabra), and yellow buckeye (A octandra) were tested for toxicity to 2-week-old Leghorn chicks and adult female Syrian hamsters. The LD50 of the water soluble portion of alcoholic extracts of horse-chestnut seeds (for hamsters and chicks) and of dried, powdered seeds (chicks only) was determined. The LD50 for a single dose of extract from horse-chestnut seeds was 10.6 mg/g of body weight for chicks and 10.7 mg/g of body weight for hamsters. The LD50 for chicks given 2 consecutive daily doses of horse-chestnut seed was 6.5 mg/g. Toxic signs included depression, muscular incoordination, paralysis, coma, and death. Extracts of seeds of Ohio buckeye were nontoxic to chicks and hamsters when fed at 80 mg/g. One of 5 hamsters died after dosing for 5 days with 80 mg/g of extract of seeds of yellow buckeye/g.

Animals↗
PubMed1984

Toxicity of Kalanchoe spp to chicks.

Leaves of Kalanchoe daigremontiana, K tubiflora, K fedtschenkoi, K tomentosa, K tomentosa X K beharensis, and 4 cultivars of K blossfeldiana were tested for toxicity to 2-week-old Leghorn chicks. These species were analyzed for percentage of alkaloids, aliphatic nitro compounds, soluble oxalates, and nitrates and were examined qualitatively for cyanogenic glycosides. The solubility of the toxic principle in K daigremontiana was determined. Leaves of K daigremontiana, K tubiflora, and K fedtschenkoi were toxic to chicks at dosage levels of 8 to 12 mg/g of body weight. Toxic signs included depression, muscular incoordination, twitching and spiraling of the neck, tremors, convulsions, paralysis, and death. Kalanchoe tomentosa, K tomentosa X K beharensis, and 4 cultivars of K blossfeldiana were nontoxic at the highest dosage levels tested. Aliphatic nitro compounds and cyanogenic glycosides were not detected in any species. Alkaloids, nitrates, and soluble oxalates were present only in nontoxic concentrations. The toxic principle in K daigremontiana was soluble in 50%, 80%, and 100% ethanol, slightly soluble in water and acetone, and insoluble in benzene, chloroform, and ether.

Animals↗
PubMed1983

The pharmacokinetics and metabolism of ethinyl estradiol and its three sulfates in the baboon.

Ethinyl estradiol sulfates are major circulating metabolites of ethinyl estradiol (EE2); this is a relationship analogous to that of endogenous estrone and estrone sulfate. Because of the wide use of contraceptives containing EE2, the pharmacokinetics of its sulfate conjugates are of some importance. In previous studies of the intermediate metabolism of ethinyl estrogens we have shown that the baboon is an appropriate animal model. Accordingly, oral and/or intravenous doses of EE2 or each of its three sulfates were administered to castrate female baboons, and plasma levels of EE2 and its sulfates were studied by specific radioimmunoassay or radioisotope counting. After intravenous administration of EE2, the 3-sulfate and the 3,17-disulfate are the major circulating metabolites. After oral dosage administration, the 3-glucuronide and, in some cases, the 3,17-diglucuronide also become important. After intravenous administration, about twice as much of the drug exists in the sulfate as in the free form, as reflected by the areas under the plasma level curves. The bioavailability of orally administered EE2 was about 60%, confirming the presence of a substantial first-pass effect. Hydrolysis at the 17-position occurs when EE2-17-sulfate is administered orally but appears not to occur with intravenous administration. EE2 and the three sulfates, given intravenously, exhibited two-compartment open-model kinetics. The elimination phase half-lives of all four compounds were similar, ranging from 8.8 to 11.2 hours. The area under the plasma level curve of EE2 resulting from the intravenous administration of the 3-sulfate was approximately 8% of the total area under the plasma level curve of both EE2 and EE2 sulfates. The ratio of the area under the plasma level curve of sulfates resulting from 3-sulfate administration compared to the other two sulfates was approximately 0.3, reflecting the existence of other metabolic pathways for its disposition.

Administration, Oral↗
PubMed1983

Subfractionation of lung surfactant. Implications for metabolism and surface activity.

Because previous studies have suggested that lung surfactant is not a simple compartment of homogeneous material, we subfractionated lamellar bodies and components of alveolar lavage from male New Zealand white rabbits, according to differences in sedimentability. We recovered two lamellar body populations at different densities in discontinuous sucrose density gradients; we separated six subfractions of alveolar lavage by differential centrifugation. To determine whether or not precursor-product relationships existed among the subfractions, we injected radioactive palmitate intravenously, killed the rabbits 1-72 h later, and measured phospholipid specific activities. The two populations of lamellar bodies had similar phospholipid composition, fatty acyl composition of phosphatidylcholine and phosphatidylglycerol, and surface activity. Light lamellar bodies had a higher ratio of phospholipid to protein, and labelled with tracer later in time than dense ones. For alveolar lavage subfractions, later labelling with tracer, lower adsorption rate and lower total protein and phosphatidylglycerol content seemed to correlate with decreasing average density and particle size as well as with the disappearance of tubular myelin structure and appearance of predominantly vesicular structure. The subfractions appear to be in a metabolic sequence in which heavier, more dense material is a precursor to lighter, less dense material. The results suggest that subfractions of surfactant are extensively recycled.

Animals↗
PubMed1983

Actin in peripheral rat lung: S1 labeling and structural changes induced by cytochalasin.

Actin was identified with S1-labeling in type I and II cells, pericytes, and capillary endothelial cells in the peripheral lung of the adult rat. In type II cells abundant actin was present in the apex of cells, in microvilli, and in close association with lamellar bodies near the cell surface. Lamellar bodies secreting their content into the lumen of alveoli were always surrounded by a thick layer of actin-like material. In specimens treated with cytochalasin D the surface of type I, type II and contractile interstitial cells became irregular. In type II cells, lamellar bodies were no longer surrounded by actin-like material and no exocytic profiles of lamellar bodies were encountered. In type II cells actin filaments may be involved in moving lamellar bodies through the cytoplasm and/or in their secretion into alveoli. These observations also suggest that intact actin filaments may be required for maintenance of cell shape in various lung cells and that cells containing actin may be capable of limited contraction.

Actins↗
PubMed1983

Actin and secretion of surfactant.

Type II cells were examined in situ in order to study the role played by actin filaments in secretion of surfactant. Following beta-adrenergic stimulation, the number of lamellar bodies per cell profile decreased substantially, an indication that exocytosis had occurred. In isoproterenol-stimulated cells decoration of actin by S1 revealed greater numbers of filaments associated with lamellar bodies, free in the cytoplasm, and associated with the cellular apex than in control cells. If cells were treated prior to beta-agonist stimulation with cytochalasin D, a drug which disrupts filamentous actin, the secretory response to the agonist was abolished. Together these two observations suggest that actin filaments participate in the intracellular movement and/or extrusion of lamellar bodies from the cells.

Actins↗
PubMed1983

Effects of herbicides on the concentration of poisonous compounds in plants: a review.

Herbicides may raise, lower, or not affect the concentration of poisonous compounds in plants. Herbicides, 2,4,5-T and silvex controlled Wasatch milkvetch (Astragalus miser var oblongifolius) and markedly reduced the concentration of miserotoxin, a poisonous aliphatic nitro compound. The concentration of phototoxic furocoumarins in the leaves of spring parsley (Cymopterus watsonii) decreased to nontoxic concentrations 4 to 5 weeks after treatment with 2,4-D. The hydrocyanic acid content of wild cherry (Prunus spp) decreased after treatment with 2,4-D and 2,4,5-T, but increased in Sudangrass (Sorghum halapense) after treatment with 2,4-D. The alkaloid concentration in Barbey larkspur (Delphinium barbeyi) increased after treatment with 2,4,5-T or silvex, decreased in horsetail (Equisetum palustre) after treatment with MCPA, and was unaffected in Datura after treatment with several herbicides. The effect of herbicides on nitrate concentration in plants was dependent upon the species of plant and the herbicide used.

Alkaloids↗