Biomedical subjects

V Castranova

Publications and source records attributed to V Castranova.

At least 145 records · Page 8Linked to original sources

PubMed1990

Platelet-activating factor-induced aggregation of rat alveolar macrophages.

Isolated rat alveolar macrophages aggregate in the presence of PAF in a dose- and cell-dependent manner. Saturation was achieved at 80 microM PAF. The response was increased linearly with cell number up to a concentration of 3 x 10(6) cells/ml, but decreased at higher cell concentrations. The stereoisomer, enantio-PAF, and the C2-acetyl hydrolyzed product, lyso-PAF, each caused aggregation of isolated rat alveolar macrophages in a manner similar to that for PAF. The PAF-induced aggregation of alveolar macrophages may be mediated through non-specific binding sites and may represent a toxic response to relatively high levels of PAF that released at localized sites.

Animals↗

PubMed1989

The potentiating action of tetrandrine in combination with chloroquine or qinghaosu against chloroquine-sensitive and resistant falciparum malaria.

Using chloroquine-sensitive (CS) and chloroquine-resistant (CR) strains of Plasmodium falciparum in vitro, interactions between tetrandrine (TT) and either chloroquine (CQ) or qinghaosu (QHS, artemisinin) were assessed using isobolograms. Sums of the fractional inhibitory concentration for the combination of the two drugs are less than one and therefore, we can conclude that in vitro TT and CQ or QHS act synergistically against CS and CR falciparum malaria. Remarkably, using CR malaria, TT can lower the IC50 dose of CQ as much as 40 fold. These drug combinations may impair the advantage that the development of CQ resistance conveys on the parasite.

Alkaloids↗

PubMed1989

Cytochrome P450-dependent alkoxyphenoxazone dealkylase activity in rat alveolar type II cells: effect of pretreatment with beta-naphthoflavone.

Cytochrome P450-dependent alkoxyphenoxazone dealkylase activity was measured in alveolar type II cells from control and beta-naphthoflavone (ip) treated-rats. Type II cells were isolated from collagenase/elastase-digested lung tissue and purified by centrifugal elutriation. The specificity of the cytochrome P450-dependent activity towards four alkoxyphenoxazones (methoxy-, ethoxy-, pentoxy-, and benzyloxyphenoxazone) was measured under conditions that minimized interference by cytosolic conjugating- and NADPH-dependent quinone reductase activities. Ethoxyphenoxazone dealkylase activity was induced 17-fold following beta-naphthoflavone treatment and was further characterized by its kinetic parameters and sensitivities toward in vitro inhibitors (Km(app) = 0.20 microM, Vmax = 1.74 pmoles resorufin min-1 (10(6) cells)-1 10(6) cells; I50 (alpha-naphthoflavone) = 0.025 microM, and I50 (metyrapone) = 72 microM). beta-Naphthoflavone pretreatment of the rats did not result in statistically significant changes in methoxy-, pentoxy-, or benzyloxyphenoxazone dealkylase activity of alveolar type II cells, although, a trend towards decrease activity was observed for benzyloxyphenoxazone. beta-Naphthoflavone pretreatment had no effect on oxygen consumption or trypan blue exclusion in alveolar type II cells and macrophage ethoxyphenoxazone dealkylase and benzyloxphenoxazone dealkylase activities were not affected by the beta-naththoflavone pretreatment. The results show that exposure to beta-naphthoflavone resulted in an increase in type II cell cytochrome P450-dependent ethoxyphenoxazone dealkylase activity but not in other alveolar type II cell or macrophage alkoxyphenoxazone dealkylase activities or in parameters that monitor viability and cell wall integrity.

Animals↗

PubMed1989

Taurine uptake by isolated alveolar macrophages and type II cells.

Evidence suggests that taurine may protect cellular membranes against oxidants (Gordon et al., Am. J. Pathol. 125: 585-600, 1986). The present study was conducted to determine if alveolar macrophages and type II cells (which are relatively resistant to oxidant injury) possess a specialized transport system for the accumulation of taurine. The results indicate that both cell types contain more taurine than plasma or whole lung. Taurine influx exhibited both carrier-mediated and simple diffusion components. Carrier-mediated uptake displayed saturation kinetics (Km = 26.3 and 22.5 microM, while Vmax = 33.2 and 4.9 pmol.10(6) cells-1.min-1 for macrophages and type II cells, respectively). Taurine uptake was dependent on extracellular sodium and inhibited by metabolic inhibitors or ouabain. Total taurine uptake by type II cells was lower than that of alveolar macrophages. However, type II cells exhibited a higher intercellular concentration of taurine (14 vs. 4 mM) because of a higher ratio of carrier-mediated uptake to leakage than with alveolar macrophages. It is possible that this specialized transport system for taurine uptake may lend these cells resistant to oxidant injury.

Animals↗

PubMed1989

Interferon production in rat type II pneumocytes and alveolar macrophages.

The time course and magnitude of interferon production induced by influenza virus were determined in type II pneumocytes and alveolar macrophages isolated from rats (Sprague-Dawley). Although the peak of interferon production was approximately 20 h in both alveolar cell types, it was more than three- to fourfold higher in type II cells than in macrophages. Dose-response relationships were noted between the virus multiplicity of induction as well as population numbers of either alveolar cell type and interferon yields. The viral-induced cytokines produced by rat type II cells and alveolar macrophages exhibit physiochemical and biological properties characteristic of interferons and, with respect to type II pneumocytes, mark their heretofore unrecognized capability to produce interferon. The best cross-species antiviral protection afforded by these rat interferons to cells of different origin, expressed as percentage of homologous species (100%), was as follows: guinea pig 50, mouse 40%, and both human and monkey 0%. The heterologous antiviral activity by interferons from either rat alveolar macrophages or type II cells on alpha interferon-sensitive guinea pig cells suggests that these cytokines may be more appreciably related to the alpha-like interferon species. The growth of influenza and Sendai viruses was precluded in both rat alveolar macrophages and type II pneumocytes. The findings herein suggest that type II cells may be a major source of alveolar interferon for activating the antiviral state and modulating alveolar cell functions requisite for lung integrity.

Animals↗

PubMed1988

Reversed-phase high-performance liquid chromatography technique for taurine quantitation.

Taurine (2-aminoethanesulfonic acid) was quantitated by reversed-phase chromatography on a C18 Resolve column using a linear gradient of 9-11% methanol in water. Glutamine was used as the internal standard. Pre-column derivatization of the amino acid with o-phthalaldehyde allowed the detection of as little as 0.1 pmol taurine. Dual ion-exchange column chromatography was employed to remove other amino acids and metabolic precursors of taurine from the samples. Cysteic acid and cysteine sulfinic acid did not interfere with taurine analysis by the high-performance liquid chromatographic method. For sample deproteinization, boiling and picric acid precipitation were used. Recovery of taurine averaged 93.5 +/- 5.0% (means +/- standard error of the mean) from standard solutions and was not affected by the method of deproteinization. Using this procedure, plasma taurine concentrations for the rat and chick were determined to be 100.7 +/- 13.1 microM and 108.0 +/- 0.3 microM, respectively. Recovery of taurine from plasma samples averaged 97.2 +/- 4.7%.

Animals↗

PubMed1988

Phenylmethylsulfonyl fluoride inhibits chemotactic peptide-induced actin polymerization and oxidative burst activity in human neutrophils by an effect unrelated to its anti-proteinase activity.

Stimulation of polymorphonuclear leukocytes with the chemotactic peptide N-formylmethionylleucylphenylalanine (fMet-Leu-Phe) causes conversion of monomeric actin to polymeric actin. We studied the role of proteinase inhibitors phenylmethylsulfonyl fluoride PMSF) and diisopropyl fluorophosphate in fMet-Leu-Phe-induced actin polymerization in polymorphonuclear leukocytes. Pre-incubation of cells with PMSF (2 mM) for 1 min caused inhibition of fMet-Leu-Phe-induced actin polymerization, as studied by 7-nitrobenz-2-oxa-1,3-diazole (NBD) -phallacidin labeling and flow cytometry. PMSF also inhibited fMet-Leu-Phe-induced hydrogen peroxide release, superoxide anion generation and chemiluminescence. In contrast, diisopropyl fluorophosphate (5 mM) was unable to inhibit fMet-Leu-Phe-induced actin polymerization and superoxide generation, but was effective in inhibiting hydrogen peroxide production and chemiluminescence. PMSF did not cause any change in membrane potential by itself and failed to inhibit the membrane potential changes induced by fMet-Leu-Phe, indicating that PMSF does not affect the binding of fMet-Leu-Phe to the receptors. The high concentration of PMSF required coupled with the fact that diisopropyl fluorophosphate was unable to inhibit fMet-Leu-Phe-induced actin polymerization suggested that this activity of PMSF might be unrelated to proteinase inhibitory activity. Polymyxin B, a membrane-active antibiotic, had an effect similar to PMSF on fMet-Leu-Phe-induced actin polymerization. This suggests that PMSF may also be acting via its membrane effect rather than its anti-proteinase effect.

Actins↗

PubMed1988

The alveolar type II epithelial cell: a multifunctional pneumocyte.

The epithelial surface of the alveoli is composed of alveolar type I and type II cells. Alveolar type I cells comprise 96% of the alveolar surface area. These cells are extremely thin, thus, minimizing diffusion distance between the alveolar air space and pulmonary capillary blood. Type II cells are spherical pneumocytes which comprise only 4% of the alveolar surface area, yet they constitute 60% of alveolar epithelial cells and 10-15% of all lung cells. Four major functions have been attributed to alveolar type II cells: (1) synthesis and secretion of surfactant; (2) xenobiotic metabolism; (3) transepithelial movement of water; and (4) regeneration of the alveolar epithelium following lung injury. Therefore, alveolar type II cells play important roles in normal pulmonary function and in the response of the lung to toxic compounds which may cause lung damage. Techniques have now been developed to isolate and purify alveolar type II epithelial cells from lung tissue. Such cellular preparations afford bioassay systems to monitor the effects of occupational or environmental pollutants on alveolar pneumocytes and should yield important information concerning the etiology of pulmonary disease in the alveolar region of the lung.

Animals↗

PubMed1988

Generation of free radicals from freshly fractured silica dust. Potential role in acute silica-induced lung injury.

Data presented here indicate that freshly fractured silica exhibits surface characteristics and biologic reactivity distinct from aged silica, and on this basis we propose that these surface features may lead to enhanced manifestations of lung injury. Grinding of silica produces approximately 10(18) Si and Si-O (silicon-based) radicals per gram of dust on the particulate surface which are characterized by an electron spin resonance (ESR) spectrum centered around g = 2.0015. These silicon-based radicals react with aqueous media to produce OH radicals, which are demonstrable using a DMPO spin trap. The concentration of silicon-based radicals in silica decreases with aging in air and exhibits a half-life of approximately 30 h, whereas its ability to generate OH radicals in aqueous solution decreases with a half-life of approximately 20 h. However, on storage in aqueous media, the concentration of silicon-based radicals and the dust's ability to generate OH radicals decrease significantly within a few minutes. Freshly ground silica is also more biologically reactive than aged silica, because freshly crushed silica activates a greater respiratory burst in alveolar macrophages than aged silica, i.e., storage of ground dust in air decreases silica-induced superoxide anion secretion, hydrogen peroxide release, and NBT reduction by 25%, 68%, and 43%, respectively. Furthermore, compared to aged silica, freshly ground silica exhibits a greater cytotoxic effect on cellular membrane integrity, i.e., a 1.5-fold increase in LDH release from macrophages, a 36-fold increase in hemolytic activity, and a three-fold increase in the ability to induce lipid peroxidation.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1986

Carrageenan stimulates reduction of nitroblue tetrazolium by human neutrophils without membrane depolarization, myeloperoxidase secretion, or increased oxygen consumption.

Carrageenan, a sulfated polyanionic polysaccharide, is commonly used to induce inflammation in experimental animals, and this model is used to screen for the effectiveness of antiinflammatory drugs. Carrageenan-induced inflammation has been attributed to a variety of autocoids including histamine, bradykinin, complement, superoxide, and prostaglandins. This study examines the effects of carrageenan on human PMN in a serum-free system. Carrageenan was found to stimulate the reduction of NBT by PMNs without stimulating membrane depolarization, oxygen consumption, H2O2 production, or myeloperoxidase secretion. Carrageenan stimulates a heat-labile, NBT-reducing system which is unassociated with the usual stimulus-response coupling seen with other PMN activators such as PMA, FMLP, and zymosan.

Carrageenan↗

PubMed1986

Measurement of phagocytosis and cell-mediated cytotoxicity by chemiluminescence.

The generation of CL by phagocytes has been shown to be a valuable tool for monitoring the activity of phagocytic cells. It has been used to investigate mechanisms by which stimulants or inhibitors act to affect the function of phagocytic cells. CL has also been used as an assay system to detect various disease states. Last, it has been shown to be a very sensitive assay system for determining the toxicity of environmental or occupational agents on phagocytic cells.

Acquired Immunodeficiency Syndrome↗

PubMed1986

Toxicity of mycotoxins for the rat pulmonary macrophage in vitro.

The presence of mycotoxins in grains is well documented. Workers in grain handling occupations are commonly exposed to grain dust aerosols. Work in our laboratory has shown that T-2 toxin is highly toxic to rat alveolar macrophages in vitro, causing loss of viability, release of radiolabeled chromium, inhibition of macromolecular synthesis, inhibition of phagocytosis, and inhibition of macrophage activation. Similarly, patulin caused a significant release of radiolabeled chromium, decrease in ATP levels, significant inhibition of protein and RNA synthesis, and inhibition of phagocytosis. The data show that both T-2 toxin and patulin are highly toxic to rat alveolar macrophages in vitro. The data further suggest that the presence of these mycotoxins in airborne respirable dust might present a hazard to exposed workers.

Animals↗

PubMed1985

Catabolism of rat surfactant disaturated phosphatidylcholines during incubation of alveolar lavage materials in vitro at 37 degrees C.

Incubation of rat alveolar lavage materials in vitro at 37 degrees C results in degradation of the endogenous surfactant disaturated phosphatidylcholines (disaturated PC). When exogenous dipalmitoylphosphatidylcholine (DPPC) vesicles are incubated with lavage materials, there is catabolism of the DPPC. The degradation process is temperature- and Ca2+-dependent and has a pH optimum of 6.5-7.0. The products formed during catabolism of [3H]palmitate- and [14C]choline-labeled disaturated PC are free palmitate and water-soluble choline products. No lysophosphatidylcholines are formed. Measurements of lactate dehydrogenase levels in lavage fluid, use of more gentle lavage techniques, use of Ca2+, Mg2+ and protein in the lavage medium, and measurements of bacterial contamination all suggest that enzymes are neither released into pulmonary lavage fluid via cellular damage nor are bacterial in origin. Degradation of surfactant disaturated PC does not occur during incubation of lavage materials from rabbits, mice or guinea pigs. These results suggest that phospholipases and/or lysophospholipases are present in rat alveolar lavage materials. Possible origins of these enzymes are discussed.

Animals↗

PubMed1985

Incorporation of [3H]palmitate and [14C]choline into disaturated phosphatidylcholines in rat alveolar macrophages.

We studied the synthesis of disaturated phosphatidylcholines in rat alveolar macrophages and, in some cases, compared it with that which occurs in isolated alveolar type II cells. Alveolar macrophages suspended in phosphate-buffered medium incorporate palmitate, choline and glycerol into disaturated phosphatidylcholines. The time-course for incorporation of palmitate into disaturated phosphatidylcholines is linear for 20-30 min and reaches a maximum in 2-3 h. Incorporation is dependent on extracellular palmitate with a Vmax (at 1 mM) of 1.53 nmol palmitate incorporated into disaturated phosphatidylcholines per 5 X 10(5) cells per 2 h and a K 1/2 of 0.19 mM palmitate. Exposure of the cells to zymosan particles increases incorporation of palmitate disaturated phosphatidylcholines by almost 2-fold, while cholinergic and beta-adrenergic agonists have no effect. On a per cell basis, alveolar macrophages incorporate only one-third to one-half as much palmitate into disaturated phosphatidylcholines as do type II cells isolated by centrifugal elutriation. The following results suggest there is extensive remodeling of disaturated phosphatidylcholines in alveolar macrophages: (1) palmitate- and choline-labeled disaturated phosphatidylcholines are catabolized by the cells; (2) the products of catabolism are palmitate and water-soluble choline products; (3) addition of unlabeled palmitate and choline to the medium enhances catabolism of the labeled phospholipid. Addition of oleate also enhances catabolism, suggesting that modification of phospholipids is not specific for the saturated variety. Some of the recently labeled disaturated phosphatidylcholines is released from alveolar macrophages into the extracellular space. Several possible functions of alveolar macrophage disaturated phosphatidylcholines are discussed.

Animals↗

PubMed1985

The response of rat alveolar macrophages to chronic inhalation of coal dust and/or diesel exhaust.

The use of diesel-powered equipment in underground mines has raised questions regarding possible synergistic effects of coal dust and diesel emissions. Therefore, the effects of chronic exposure of rats to coal dust and/or diesel exhaust on various properties of alveolar macrophages were investigated. Inhalation exposure of rats was 7 hr/day, 5 days/week for 2 years. Exposure groups were: filtered air controls, 2 mg/m3 coal dust, 2 mg/m3 diesel particulate, and 1 mg/m3 coal dust plus 1 mg/m3 diesel exhaust. Exposure to coal dust and/or diesel exhaust had little effect on oxygen consumption, membrane integrity, lysosomal enzyme activity, or protein content of alveolar macrophages. However, exposure to coal dust increased macrophage yield, enhanced chemiluminescence, and increased the activity of the cell membrane (i.e., increased cellular spreading and surface ruffling). In contrast, diesel emissions depressed chemiluminescence and decreased the ruffling of the cell membrane. Therefore, the data suggest that exposure to coal dust and/or diesel exhaust does not affect the viability of alveolar macrophages. However, coal dust may activate alveolar macrophages while diesel emissions may depress the phagocytic activity of these cells. The combination of exposures to coal dust and diesel exhaust results in a phagocytic activity which is an average of the effects of separate exposures.

Animals↗

PubMed1985

Toxicity of the mycotoxin patulin for rat alveolar macrophages.

Agricultural workers are exposed to a variety of organic dusts containing fungi and their secondary metabolites. Patulin, a polyketide lactone mycotoxin produced by several common species of Aspergillus and Penicillium, is found in corn silage. Patulin is toxic in experimental animals and has been reported to be mutagenic, teratogenic, and carcinogenic. The cytotoxicity of patulin was studied in rat alveolar macrophages in vitro. The effects of patulin on membrane integrity were studied by measuring cell volume changes and release of 51Cr. There was a significant release of 51Cr after 1 hr exposure to submillimolar concentrations of patulin. Similarly, there was a significant decrease in ATP in cell cultures exposed to 0.5 mM patulin for 15 min and in cultures exposed to 0.05 mM patulin for 2 hr. There was a significant increase in mean cell volume after 2 hr exposure to 1.0 mM patulin but not after a 1 hr exposure. The effects of patulin on protein and RNA synthesis were studied by monitoring the incorporation of [3H]leucine and [3H]uridine, respectively. Inhibitions of protein and of RNA synthesis were both dose and time dependent. Protein synthesis was the most sensitive cellular parameter studied, with 50% inhibition after 1 hr at ca. 0.002 mM patulin. The data demonstrate that patulin is cytotoxic for rat alveolar macrophages in vitro.

Adenosine Triphosphate↗

PubMed1984

Granulocyte response to oxidized FMLP. Evidence for partial inactivation of FMLP.

We prepared FMoxLP by oxidation of FMLP and evaluated its ability to trigger a variety of granulocyte responses. FMoxLP was found to depolarize granulocyte membranes; increase granulocyte oxygen consumption, superoxide production, and hydrogen peroxide production; compete with FMLP for binding to granulocytes; and stimulate granulocyte chemotaxis. Against all of these granulocyte functions, FMoxLP was considerably less potent than the parent FMLP. When luminol-dependent-granulocyte chemiluminescence (CL) was studied, FMoxLP was observed to be a more potent stimulus of this response than FMLP. This increased CL activity of FMoxLP may be related to nonoxidative burst mechanisms. Our results indicate that FMoxLP retains a significant amount of the biological activity of FMLP (albeit in general less potent). The biological importance of the observed activities of FMoxLP must await further investigation.

Animals↗

PubMed1984

Toxicity of metallic ions in the lung: effects on alveolar macrophages and alveolar type II cells.

Airborne metallic particulates are associated with fossil-fueled power plants, automobile exhausts, metal mining, and metallurgical smelters. Therefore, the possible toxic effects of metals on the lung are of environmental and occupational concern. In this investigation we determined the effects of in vitro exposure to metallic ions on the following parameters: oxygen consumption and membrane integrity of alveolar macrophages and type II cells, and chemiluminescence of zymosan-stimulated alveolar macrophages. Cu2+ and Zn2+ exhibited marked toxicity to isolated alveolar macrophages and type II cells, while V3+ exhibited intermediate toxicity. In contrast, short-term in vitro exposure to As5+ and Se4+ had little effect on alveolar macrophages and type II cells. Although the data suggest that exposure to certain metals may be harmful to the lung, the various pulmonary parameters tested in this investigation display differing susceptibility to metal exposure. That is, metals are less toxic to alveolar type II cells than to alveolar macrophages. Our data also indicate that chemiluminescence is the most sensitive assay for monitoring the viability of alveolar macrophages, while oxygen consumption is a sensitive assay for type II cells.

Animals↗