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Biomedical subjects

D Acosta

Publications and source records attributed to D Acosta.

At least 217 records · Page 12Linked to original sources
PubMed1978

Contractile activity of neonatal heart cells in culture derived from offspring of exercised pregnant rats.

5-day-old neonatal offspring of exercised or non-exercised pregnant Sprague Dawley rats were used to prepare primary cultures of beating myocardial cells. The cells from the exercise group exhibited a slower beating rate for both single and aggregate cells; a larger cell size; an increased percentage of contracting cells; a greater capacity to form confluent monolayers, and a greater viability. It was concluded that exercise during the period of pregnancy produced morphological alterations in the myocardium of the progeny.

Animals↗
PubMed1978

Primary monolayer cultures of postnatal rat liver cells with extended differentiated functions.

Monolayers of liver cells cultured from postnatal rats were grown in two types of media. One set of cultures was grown in selective medium which contained ornithine but was deficient in arginine; the other set was grown in nonselective medium which contained arginine but no ornithine. The cultures that were grown in the nonselective medium contained primarily a mixture of two cell types found in the liver: parenchymal hepatocytes and fibroblast-like cells. The fibroblast cells tended to overgrow the hepatocytes after several days in culture. In contrast, fibroblast overgrowth was inhibited in cultures grown in the selective, arginine-deficient medium, thereby resulting in relatively pure cultures of functional parenchymal hepatocytes. Comparative studies of sulfobromophthalein (BSP) uptake showed that the cultures grown in selective medium continued to be active much longer than the cultures grown in the nonselective medium. Pyruvate kinase assays revealed that the cultures grown in selective medium contained primarily the L-isoenzyme type which is characteristic of parenchymal hepatocytes. Cultures grown in nonselective medium contained a mixture of L- and M-isoenzymes which is indicative of nonparenchymal liver cells. The reported results indicate that selective, arginine-deficient medium permits primarily the growth of parenchymal hepatocytes found in neonatal rat liver.

Animals↗
PubMed1978

Ischemic myocardial injury in cultured heart cells: leakage of cytoplasmic enzymes from injured cells.

An in vitro model of myocardial ischemia has been established with primary monolayer cultures of postnatal rat myocardial cells. Ischemic conditions were simulated in vitro by subjecting the myocardial cell cultures to various levels of oxygen and glucose deprivation. The experimental protocol consisted of treatment with 20% or 0% O2 and 1000, 500 or 0 mg glucose per 1 of medium for 4 or 24 hr. Control cultures were treated with 20% O2 and 1000 mg glucose. After the ischemic treatments, cultures of beating muscle (M) cells were evaluated for signs of injury, i.e. leakage of cytoplasmic enzymes into the culture medium. Differences were found in leakage of lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) from the cultures that were exposed to partial ischemia of glucose deprivation and from those cultures that were exposed to total ischemia of oxygen and glucose deprivation. Glucose deprivation along resulted in a slight-to-moderate loss of LDH and CPK from the cells, whereas total ischemia resulted in a significant release of the two cytoplasmic enzymes. When the cultures were allowed to recover after ischemic treatment in complete medium (1000 mg glucose) and a normal atmosphere of 20% O2, they had levels of LDH leakage comparable to those of control cultures. Cell viability and total protein content of the ischemic cultures did not differ significantly from controls.

Cell Survival↗
PubMed1978

Cytotoxicity of butylated hydroxytoluene and butylated hydroxyanisole in cultured heart cells.

Butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) at concentrations of 100 ppm (0.45 and 0.55 mM, respectively) produced a marked leakage of lactic dehydrogenase (LDH) from cultured myocardial and endotheloid cells into the culture medium. At this concentration both BHT and BHA markedly depressed the beating rate of cultured heart cells with maximum inhibition occurring within 1 h after antioxidant exposure. Morphologically the appearance of cells in the presence of 100 ppm BHT and BHA was similar to the appearance of control cells. However, when BHT and BHA concentrations were increased to 1000 ppm (4.5 and 5.5 mM, respectively), marked cell lysis was seen after a 1 h exposure period. The results of this study suggest that both BHT and BHA, in relatively large concentrations, produce injury to myocardial cells in culture.

Animals↗
PubMed1977

Ischemic myocardial injury in cultured heart cells: preliminary observations on morphology and beating activity.

An in vitro model of myocardial ischemia has been established with primary monolayer cultures of neonatal rat heart cells. Ischemic conditions were simulated in vitro by subjecting the heart cell cultures to various levels of oxygen and glucose deprivation. After the ischemic treatments, cultures of beating muscle (M) cells were evaluated for functional and morphological changes. The experimental protocol consisted of treatment with 20% or 0% O2 and 1000, 500 or 0 mg glucose per 1 of medium for 4, 12 or 24 hr. Control cultures were treated with 20% O2 and 1000 mg glucose. The morphological alterations induced by the deficiency of O2 and glucose in the medium were the formation of pseudopodia and cytoplasmic vacuoles; increased cytoplasmic granulation; and the formation of abnormal cell shapes, such as long, spindly shaped M cells. There was a time-dependent decrease in beating activity as the M cells were exposed to longer durations of ischemic conditions. However, if the cultures were replenished with complete medium (1000 mg glucose) and 20% O2, the cells regained their ability to beat.

Cells, Cultured↗
PubMed1977

Cardiotoxicity of diazepam in cultured heart cells.

The responses of primary cultures of rat myocardial cells to diazepam (Valium) were evaluated. The cells were exposed to 4, 16 or 32 microgram/ml of diazepam for 1, 4 or 24 h. The cultures were evaluated for changes in beating activity and morphology and for cytotoxic effects. After the 1-h treatment exposure, the cultures exhibited tachycardia which was dose-dependent. The longer durations of treatment either produced arrhythmias or caused a loss of beating. Major morphological alterations observed were the formation pseudopodia and increased cytoplasmic granulation. Cytotoxicity was measured quantitatively by leakage of lactic dehydrogenase (LDH) from the cells into the media and by cell viability. Moderate amounts of LDH were leaked from the cells after exposure to diazepam for 4 h. After 24 h of treatment with the higher concentrations of diazepam, cell viability was greatly reduced.

Animals↗
PubMed1975

A permeability test for the study of mitochondrial injury in in vitro cultured heart muscle and endothelioid cells.

A cytochemical permeability test for the detection of injury to in situ mitochondria of cultured heart cells is presented. The test is based on the increased rate at which injured mitochondria stain for succinate dehydrogenase activity. Whereas an intact inner mitochondrial membrane limits the rate at which Nitro Blue tetrazolium and phenazine methosulphate reach succinate dehydrogenase, injured mitochondria allow these reactants to reach the enzyme more rapidly to form microscopically-observable formazan granules. The extent of staining at fixed durations of incubation with the reactants was assessed on a blind basis with pseudo dark-field microscopy, using a standardized rating scale. Differences in the staining of control and treated cells were analysed statistically by a semi-quantitative method. Treatment of the cultures with either vitamin A or chlorpromazine, resulted in more rapid mitochondrial staining. Brief pre-fixation of the cells with cold acetone also labilized the mitochondria as did a delay in the change of culture medium.

Animals↗
PubMed1975

Cholesterol and beta-lipoprotein on lipid inclusions and lysosomal and mitochondrial permeability of cultured heart muscle and endothelioid cells.

Cultured rat heart endothelioid cells were used to study the effect of beta-lipoprotein and cholesterol on the production and persistence of cellular lipid inclusions. Both heart endothelioid and muscle cells were used to study the effects of beta-lipoprotein with and without cholesterol or cholesterol esters on lysosomal or mitochondrial lability. Beta lipoprotein enhanced the production and maintanence of lipid inclusions. In the concentration employed (20mg%) it alone produced no effect after 72 hours on lysosomal or mitochondrial lability but with cholesterol, cholesterol stearate, cholesterol oleate or cholesterol linoleate (5mg%) there was a trend toward labilization.

Animals↗
PubMed1975

Labilization of lysosomes and mitochondria in situ by hypoxia and hypoxia-related factors.

Primary cultures of rat heart muscle and endothelioid cells were used to study the labilization of lysosomes and mitochondria by hypoxia, "hypoxia substitutes", and the in vivo-related factors of free fatty acid and pH. Subliminally-active levels tested were: hypoxia (1% O2/4 days), 5x10(-6)M sodium stearate: albumin in 6:1 ratio/30 min, KCN (1x10(-3)M/1 hr), 2 deoxy-glucose (3x10(-2)M/12 hr), acidosis (pH 6.9/30 min) and combinations. KCN plus 2-DG labilized the organelles in both cell types. Sensitivity to injury was in the order mitochondria greater than lysosomes and muscle cells greater than endothelioid cells.

Animals↗
PubMedDate not supplied

Applications of novel affinity cassette methods: use of peptide fusion handles for the purification of recombinant proteins.

In this article, recent progress related to the use of different types of polypeptide fusion handles or 'tags' for the purification of recombinant proteins are critically discussed. In addition, novel aspects of the molecular cassette concept are elaborated, together with areas of potential application of these fundamental principles in molecular recognition. As evident from this review, the use of these concepts provides a powerful strategy for the high throughput isolation and purification of recombinant proteins and their derived domains, generated from functional genomic or zeomic studies, as part of the bioprocess technology leading to their commercial development, and in the study of molecular recognition phenomena per se. In addition, similar concepts can be exploited for high sensitivity analysis and detection, for the characterisation of protein bait/prey interactions at the molecular level, and for the immobilisation and directed orientation of proteins for use as biocatalysts/biosensors.

Affinity Labels↗
PubMedDate not supplied

A digitized fluorescence imaging study of intracellular Ca2+, pH, and mitochondrial function in primary cultures of rabbit corneal epithelial cells exposed to sodium dodecyl sulfate.

Primary cultures of rabbit corneal epithelial cells have been developed as an in vitro system to predict irritancy potential and delayed cytotoxicity of surfactants in our laboratory. The objective of this study was to evaluate the effects of the surfactant sodium dodecyl sulfate (SDS), a common ingredient in consumer products, on intracellular Ca2+, pH, and mitochondrial function in this culture system. Ca2+ and pH were measured in single living corneal epithelial cells by ratio imaging of fura-2 and 2,'7'-bis(carboxyethyl)-5(6)-carboxyfluorescein fluorescence, respectively. Mitochondrial function was examined by probing mitochondrial membrane potential with the fluorescent dye rhodamine 123 and by measuring the ratio of ATP to ADP with an HPLC method. Cell viability was determined by fluorescence imaging of propidium iodide in single cells and LDH leakage assay in populations of cells. SDS (40 micrograms/ml) increased intracellular Ca2+ from 180 +/- 28nM to 453 +/- 86 nM within 2 min, and induced intracellular acidification (pHi dropped 0.3 units in 15 min). Treatment of the cultures with SDS also resulted in dissipation of the mitochondrial membrane potential and decrease of intracellular ATP/ADP. SDS-induced Ca2+ elevation and intracellular acidification preceded the loss of cell viability observed 20 min after exposure. However, SDS-induced cell injury does not appear to be triggered by extracellular Ca(2+)-influx, as absence of extracellular Ca2+ did not attenuate SDS-induced cytotoxicity while it completely blocked ionomycin-induced cytotoxicity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗
PubMedDate not supplied

Development of a primary culture system of rat kidney cortical cells to evaluate the nephrotoxicity of xenobiotics.

A method has been developed for preparing primary monolayer cultures of postnatal rat kidney cortical epithelial cells. These cultures maintained differentiated cell functions and epithelial-like morphology for several days in culture. The presence of alkaline phosphatase and maltase was used to confirm the presence of cells from the renal cortex. The concentrations of these enzymes were maintained in culture until day 3, but had declined significantly by day 5. Similar patterns were observed with cytochrome P-450 and glutathione content, although their concentrations remained stable from day 3 to day 5. Mercuric chloride, cadmium chloride and acetaminophen were evaluated for nephrotoxicity in this culture system. Treatment with these compounds resulted in dose-dependent changes in cell morphology and in biochemical parameters such as lactate dehydrogenase leakage, alkaline phosphatase activity and cellular glutathione content. With this culture system, it was possible to detect the acute toxicities of compounds that produce varying degrees of renal injury. Further development of this kidney culture system may have value in detecting potential nephrotoxins and in studying their mechanisms of toxicity.

Acetaminophen↗
PubMedDate not supplied

Cytotoxicity of caffeine in cultured heart cells.

The cytotoxic effect of caffeine on myocardial cells was evaluated in primary cultures of rat heart muscle (M) and endothelioid (E) cells. The cells were exposed to 5, 10, or 20 mM caffeine for 6, 12, or 24 h. As an index of cell injury produced by the treatments, in situ changes in lysosomal membrane permeability were measured by a sensitive cytochemical technique. The highest concentration of caffeine (20 mM) produced such toxic signs as reduced cell viability, increased vacuolization, and pseudopod formation. At the lower concentrations, caffeine labilized lysosomal membranes of M cells more easily than those of E cells. Pretreatment with hydrocortisone prior to exposure to caffeine protected E and M cell lysosomes from the labilizing effects of caffeine.

Animals↗