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Biomedical subjects

D Acosta

Publications and source records attributed to D Acosta.

At least 199 records · Page 11Linked to original sources
PubMed1983

Cellular injury of primary cultures of rat myocytes incubated in calcium-free medium followed by recovery in calcium.

Primary monolayer cultures of rat myocardial cells were used to study the cellular injury that occurs when calcium is reintroduced after a period of calcium depletion. Cultures were treated with a calcium-free balanced salt solution (BSS) for 2 h and were then incubated for different time periods in the presence of normocalcemic BSS (2.5 mM CaCl2). Myocyte calcium content was determined after the calcium-free period and after incubation in the presence of calcium. Leakage of cytoplasmic lactate dehydrogenase (LDH) into the medium was used as an index of cell injury. At the end of the calcium-free period there was a significant decrease in the total cellular content of calcium, and LDH release was minimal. After incubation in normocalcemic BSS, the myocyte calcium content increased progressively with time and cellular injury was manifested by significant leakage of LDH. The calcium content of treated cells reached control levels 10 min after calcium repletion. Maximal leakage of LDH was observed 60 min after the restoration of calcium. The calcium content of treated cultures was higher than that of control cultures 120 min after incubation in normocalcemic BSS.

Animals↗
PubMed1983

Prevention by L(-) ascorbic acid of isoproterenol-induced cardiotoxicity in primary cultures of rat myocytes.

Primary cultures of rat myocytes were exposed to various doses of L-isoproterenol (ISO) for 4, 12 and 24 h. L-ascorbic acid (AA) was added to some cultures immediately after exposure to ISO to determine if antioxidants reduce the toxicity caused by ISO. Leakage of lactate dehydrogenase (LDH) and cell viability were used as indices of cell injury. A significant increase in LDH release was found 24 h after exposure to 1 X 10(-4) M ISO alone. Higher doses (5 X 10(-4) and 1 X 10(-3) M) caused significant enzyme release 4, 12 and 24 h after exposure. The viability of cultures exposed to toxic doses of ISO for 4 h was not affected. A dose-dependent decrease in cell viability was observed 12 h and 24 h after exposure to ISO. L-ascorbic acid (5 X 10(-3) and 1.5 X 10(-2) M) significantly reduced the LDH release caused by ISO. The enzyme release from cultures exposed to 5 X 10(-4) and 5 X 10(-3) M AA alone was similar to that of control cultures. However, 1.5 X 10(-2) and 3 X 10(-2) M AA caused marked LDH release. The viability of cultures subjected to ISO in the presence of 5 X 10(-3) M AA was similar to that of controls. Our results show that AA protects against the LDH release and decreased cellular viability caused by toxic doses of ISO.

Animals↗
PubMed1983

Assessment of functional, morphological, and enzymatic tests for acute nephrotoxicity induced by mercuric chloride.

The relative merits of a comprehensive series of contemporary methods for detection of acute nephrotoxicity were evaluated. Male Sprague-Dawley rats were given 0, 0.25, 0.5, 1.0, or 3.0 mg mercuric chloride (HgCl2)/kg body weight by ip injection. Indices of nephrotoxicity were examined 8, 24, 48, 72, and 96 h later. Alterations in urine osmolality, volume, and protein levels were seen within 24 h in response to 1 mg/kg or more of HgCl2. Administration of 0.5-3.0 mg/kg produced dose-dependent increases in urinary excretion of maltase activity and glucose by 24 h, the period of peak effect. There was no increase in maltase or alkaline phosphatase (AP) activity in the serum of these animals. Enzymuria was not apparent in rats that had marked elevations in serum AP, argininosuccinate lyase, and ornithine carbamyl transferase activities as a result of physical (i.e., dichlorodifluoromethane-frozen) or chemical (carbon tetrachloride-induced) damage of the liver. Morphological alterations, in the proximal tubular epithelium of perfusion-fixed kidneys from HgCl2-dosed rats, paralleled the changes in enzyme excretion with respect to time of onset and dose-effect. There was a dose-dependent inhibition of tetraethylammonium (TEA) and p-aminohippurate (PAH) uptake by renal cortical slices at 24 h. Interestingly, increases in uptake of TEA and PAH were seen 8 h after a 1-mg/kg dose. Clearance of inulin and PAH in vivo were altered at 8 h by 0.5 and 1 mg/kg. Marked depression of these functional indices was seen at 24 h, by which time blood urea nitrogen (BUN) levels were increased. The 0.5- and 1.0-mg/kg doses also produced time- and dose-dependent increases in intracellular Na+ content which were maximal at 24 h. These results illustrate the importance of using a combination of biochemical and functional tests to elucidate the sequence of events in the kidney following toxic insult. Nevertheless, some of the simpler, traditional techniques (e.g., histopathology, urinalyses, BUN) were sensitive and organ-specific, and should continue to be very useful in nephrotoxicity testing/screening.

Animals↗
PubMed1982

Lack of cytotoxicity of ticrynafen in primary cultures of rat liver cells.

Primary cultures of hepatocytes obtained from neonatal Sprague-Dawley rats were grown in arginine-deficient, ornithine-supplemented medium to inhibit fibroblastic overgrowth and to selectively isolate relatively pure cultures of parenchymal hepatocytes. This system of primary hepatocytes was used to study the potential cytotoxicity of ticrynafen by measuring cytoplasmic enzyme leakage, cell viability,, and total protein per culture dish. Hepatic cultures were treated with the drug in concentrations ranging from 10(-3)M to 10(-6)M and for durations from 2 to 8 h. The results of the study indicate that ticrynafen was minimally toxic to the hepatocytes.

Animals↗
PubMed1982

Cadmium toxicity in primary cultures of rat hepatocytes.

Primary cultures of rat hepatocytes served as an experimental model to evaluate the cytotoxicity of cadmium chloride. Cellular injury was assessed by a series of enzymatic and functional indices in 24-h-old cultures exposed for 1 h to concentrations of cadmium chloride ranging from 50 to 400 muM. In cultures that were evaluated immediately after the 1-h exposure to cadmium, little evidence of toxicity was observed as evaluated by total cellular protein content and cell viability. In similarly treated cultures, leakage of lactate dehydrogenase from the hepatocytes into the culture medium was increased in a dose-dependent manner. The most sensitive indicators of cadmium toxicity proved to be two parameters of metabolic activity: lactate-to-pyruvate (L/P) ratios, and intracellular levels of urea. Cadmium exposure produced substantial increases in L/P ratios and decreases in urea content in the cultured liver cells. If the cultures were allowed to recover by replacing the cadmium-containing medium after 1 h of exposure with fresh medium for 24 h, cellular protein content and cell viability were shown to decrease by 40%. These findings indicate that measures of metabolic integrity of cultured hepatocytes are more sensitive indices of early cadmium cytotoxicity than are routine, nonspecific measures such as cellular protein content and dye-exclusion viability tests, which detect the later stages of cell injury, i.e., cell death.

Animals↗
PubMed1982

In vitro comparative toxicity of selected drugs and chemicals in HeLa cells, Chang liver cells, and rat hepatocytes.

The cytotoxicity of 16 agents was compared in four different in vitro cellular systems: HeLa cells, Chang liver cells, freshly isolated rat hepatocytes in suspension, and primary monolayer cultures of postnatal rat hepatocytes. The compared cytotoxicity values had been obtained by different techniques: inhibition of spreading of HeLa cells by 50% after 24 hr incubation and leakage of lactate dehydrogenase (LDH) by 50% in Chang liver cells, isolated rat hepatocytes in suspension, and primary cultures of rat hepatocytes after 4, 1, and 3 or 24 hr incubation with the chemicals. Carbon tetrachloride, halothane, acetaminophen, and tetracycline were more toxic to the hepatocytes compared with the two cell lines. Alcohol, sodium salicylate, caffeine, papaverine, nitrofurantoin, and five tricyclic antidepressants showed similar toxicity in all compared cellular systems. Thus, the agents with a known or suspected metabolism-mediated liver toxicity indeed had a high differential hepatotoxicity in vitro.

Animals↗
PubMed1981

Evaluation of the cytotoxicity of tricyclic antidepressants in primary cultures of rat hepatocytes.

Primary cultures of hepatocytes from postnatal Sprague-Dawley rats were grown in arginine-deficient, ornithine-supplemented medium to inhibit fibroblastic overgrowth and to selectively isolate relatively pure cultures of parenchymal hepatocytes. This system of primary cultures of rat hepatocytes was utilized to evaluate the cytotoxicity of certain tricyclic antidepressant drugs (TCAs). The compounds tested were chosen to represent two distinct chemical classifications of TCAs: the dibenzazepine derivatives, imipramine (1) and desipramine (D), and the dibenzocycloheptadiene derivatives, amitriptyline (A) and nortriptyline (N). The study also allowed direct comparison of the parent tertiary amines, A and I, and their respective demethylated pharmacologically active metabolites, N and D. The hepatotoxicity of the compounds was determined by measuring leakage of cytoplasmic enzymes, lactate dehydrogenase (LDH) and glutamic-pyruvic transaminase (GPT), into the culture medium and by assessing cell viability by the trypan blue dye exclusion test. LDH leakage was a more sensitive index of early cellular injury in this study. The compounds demonstrated a dose- and time-dependent order of toxicity; their hepatotoxicity potency was ranked as A = N greater than D greater than I.

Alanine Transaminase↗
PubMed1980

Reduction of cell injury in hypoxic cultures of rat myocardial cells by methylprednisolone.

An in vitro model to study myocardial cell injury was developed with primary monolayer cultures of rat myocardial cells. Two important conditions associated with myocardial ischemia were simulated by depriving the cultures of oxygen and glucose for a specified period of time. Cellular injury caused by hypoxia and glucose deprivation resulted in significant leakage of lactate dehydrogenase (LDH) from the cells into the culture medium. The cells were not lethally injured by treatments as reflected by a lack of change in cell viability and protein content when compared to controls. Pretreatment of cultures with methylprednisolone for 24 hr provided protection to the cells when challenged by hypoxia and glucose deprivation. Methylprednisolone exhibited a dose-response effect in reducing LDH leakage in cultures, which were subsequently deprived of oxygen and glucose for 4 hr. Similar pretreatment with hydrocortisone had no effect in limiting cellular injury in hypoxic and glucose-deprived cultures.

Animals↗
PubMed1979

Injury to primary cultures of rat heart endothelial cells by hypoxia and glucose deprivation.

Primary cultures of rat heart endothelial cells were subjected to simulated conditions of ischemia: hyposia and glucose deprivation for 4 and 24 hr. Cellular injury was evaluated by measuring changes in viability, total protein, cellular morphology, and leakage of cytoplasmic enzymes from the cells into the culture medium. Deprivation of oxygen and glucose for 4 or 24 hr did not lethally injure the cells as noted by no change in cell viability, morphology, and total protein when compared to controls. However, reversible or non-lethal cellular injury was produced as reflected by a significant release of lactate dehydrogenase (LDH) from the cells into the medium after treatment with hypoxia and glucose deprivation for 4 or 24 hr. When the cultures were deprived of glucose, but were oxygenated, cellular injury was not evident after 24 hr. Deprivation of oxygen but not glucose resulted in significant loss of LDH after 4 or 24 hr. When the cultures were allowed to recover after oxygen and glucose deprivation in complete medium containing 1000 mg glucose per 1 and a normal atmosphere of 20% O2, they had levels of LDH leakage comparable to those of control cultures.

Animals↗