Measurement of tau decays involving eta mesons.
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Journal Article↗
Biomedical subjects
D Acosta
Publications and source records attributed to D Acosta.
Evaluation of surfactant cytotoxicity potential by primary cultures of ocular tissues: I. Characterization of rabbit corneal epithelial cells and initial injury and delayed toxicity studies.
This investigation was undertaken to develop cytotoxicity assay systems using primary cultures of rabbit corneal epithelial cells as an experimental model to evaluate oculotoxic agents and the ability of these in vitro assay systems to predict irritancy potential and delayed toxicity. We have characterized the epithelial nature of the cultures by identifying keratins with antikeratin antibodies (AE1/AE3) and by demonstrating metabolic enzymes important to the integrity of the cells: lactate dehydrogenase, glucose 6-phosphate dehydrogenase and aldolase. Eight surfactants were compared and ranked according to their cytotoxic potential. We evaluated cytotoxicity by measuring leakage of the cytosolic enzyme, lactate dehydrogenase, into the medium, by making morphological observations and by assessing lysosomal neutral red uptake and mitochondrial 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) reduction. The cells were treated for 1 h with the surfactants and the possibility of delayed toxicity was evaluated 24 h after removal of the surfactant. The cytotoxicity of the different types of surfactants as shown by all the tests was cationic > anionic = amphoteric > non-ionic. Triton X-100, a non-ionic surfactant but a severe irritant, had a ranking similar to anionic surfactants. The in vitro rankings corresponded well to reported in vivo Draize rabbit eye test data. The 24-h test for lactate dehydrogenase leakage showed that mild and non-irritating surfactants did not demonstrate any subsequent damage after a 1-h exposure, but the extreme and severe surfactants continued to show further damage after the 1-h exposure. These in vitro findings were similar to reported in vivo results. The neutral red and MTT tests did not adequately predict the prolonged toxicity of the more irritating surfactants, as was demonstrated by the lactate dehydrogenase leakage test. We conclude that in vitro cytotoxicity assays using primary cultures of rabbit corneal epithelial cells may be used to rank the cytotoxic potential of surfactants, but only the lactate dehydrogenase leakage test was able to assess prolonged cell injury.
Animal Testing Alternatives↗
Isospin mass splittings from precision measurements of D*-D mass differences.
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Journal Article↗
A digitized-fluorescence-imaging study of mitochondrial Ca2+ increase by doxorubicin in cardiac myocytes.
The objective of the present study was to investigate the role of mitochondrial Ca2+ in doxorubicin-induced cell injury. The effect of doxorubicin on cultured cells was investigated by digitized fluorescence imaging. The Ca2+ sensitive fluorescent dye fura-2 was used to estimate cytosolic, mitochondrial and total cellular Ca2+. Rhodamine 123 was used to estimate the mitochondrial membrane potential, and cellular ATP was determined by h.p.l.c. The data showed that doxorubicin induced greater-than-2-fold increases in mitochondrial Ca2+ before changes in cytosolic Ca2+ could be detected. An increase in mitochondrial Ca2+ paralleled the observed dissipation in mitochondrial membrane potential. Cellular ATP levels appeared to decrease as a result of mitochondrial dysfunction, which in turn produced greater-than-2-fold increases in cytosolic Ca2+. The data suggest that doxorubicin-induced alterations in mitochondrial Ca2+ homoeostasis are associated with a dissipation in energy conservation, which may result in cell injury.
Adenosine Triphosphate↗
Toxicity assessment of toxins T-514 and T-544 of buckthorn (Karwinskia humboldtiana) in primary skin and liver cell cultures.
The present study was undertaken to assess and compare the in vitro cytotoxicity of toxins T-514 and T-544 of Buckthorn (Karvinskia humboldtiana) using primary cultures of rat hepatocytes and keratinocytes. Cell cultures were exposed to 6, 12, 25 and 50 microM concentrations of the toxins for 2, 4, 6 and 24-h periods. Cytotoxicity was determined by release of the cytoplasmic enzyme, lactate dehydrogenase (LDH), in culture media, methylthiazoltetrazolium (MTT) reduction and neutral red (NR) uptake. An increase in LDH leakage was observed in liver cell cultures as early as 2 h with 50 microM T-544 and with 6 microM T-514 and T-544 at 6 h and 24 h, respectively. In the NR assay the toxicity was evident at 2 h with 12 microM T-514 and T-544 and with 6 microM concentrations of both toxins at 6 h. On the other hand, a decrease in MTT reduction was detected at 4 h with 50 microM concentrations of both toxins and with 25 microM T-544 and 12 microM T-514 at 6 h and 6 microM T-514 and T-544 at 24 h. Both toxins were shown to be highly hepatotoxic; T-514 was more toxic than T-544. In the skin cell cultures, the toxicity of the toxins was not as severe and was not expressed until 12 h of exposure.
Animals↗
Toxicity assessment of toxins T-514 and T-544 of buckthorn (Karwinskia humboldtiana) in primary skin and liver cell cultures.
The present study was undertaken to assess and compare the in vitro cytotoxicity of toxins T-514 and T-544 of buckthorn (Karwinskia humboldtiana) using primary cultures of rat hepatocytes and keratinocytes. Cell cultures were exposed to 6, 12, 25 and 50 microM toxins for 2-, 4-, 6- and 24-h periods. Cytotoxicity was determined by release of the cytoplasmic enzyme, lactate dehydrogenase (LDH), in culture media, methylthiazoltetrazolium (MTT) reduction and neutral red (NR) uptake. An increase in LDH leakage was observed in liver cell cultures as early as 2 h with 50 microM T-544 and with 6 microM T-514 and T-544 at 6 h and 24 h, respectively. In the NR assay the toxicity was evident at 2 h with 12 microM T-514 and T-544 and with 6 microM concentrations of both toxins at 6 h. On the other hand, a decrease in MTT reduction was detected at 4 h with 50 microM concentrations of both toxins and with 25 microM T-544 and 12 microM T-514 at 6 h and 6 microM T-514 and T-544 at 24 h. Both toxins were shown to be highly hepatotoxic; T-514 was more toxic than T-544. In the skin cell cultures, the toxicity of the toxins was not as severe and was not expressed until 12 h of exposure.
Animals↗
Production of a toxic, novel mammalian metabolite of N-methylcarbazole predicted by a fungal cell model of mammalian metabolism.
The formation of N-hydroxymethylcarbazole (NHMC), carbazole, 1-hydroxy-N-methylcarbazole, 2-hydroxy-N-methylcarbazole, and 3-hydroxy-N-methylcarbazole as products of mammalian liver microsomal metabolism of N-methylcarbazole (NMC) has been documented by several investigators. In previous studies in our laboratory, the fungus Cunninghamella echinulata (ATCC 9244) produced two new metabolites, 3-hydroxy-N-hydroxymethylcarbazole (3-OH-NHMC), and 3-hydroxycarbazole (3-OH-carbazole), in addition to the known mammalian metabolites, NHMC and carbazole. One of the two novel metabolites isolated from the microbial models, 3-OH-NHMC, was also identified and characterized in rat liver microsomes by analytical (HPLC) and spectral (UV and NMR) comparisons with a reference standard. The two metabolites, 3-OH-NHMC and 3-OH-carbazole, were shown to be cytotoxic to cultured rat hepatocytes as assessed by lactate dehydrogenase (LDH) leakage and neutral red (NR) uptake. These studies demonstrate the prospective potential of microbial models for predicting the formation of metabolites from drugs and other xenobiotics in mammalian systems.
Animals↗
Changes in glutathione and cellular energy as potential mechanisms of papaverine-induced hepatotoxicity in vitro.
The purpose of this study was to elucidate the mechanism of hepatotoxicity of papaverine hydrochloride (papaver) in vitro. To evaluate the role of metabolism in the toxicity of papaver, cells were pretreated with SKF-525A or benzyl imidazole (cytochrome P450 system inhibitors) for 24 hr at 1 x 10(-5) or 1 x 10(-4) M, respectively, or with phenobarbital sodium (cytochrome P450 system inducer) for 3 days at 2 x 10(-3) M. Cells then were exposed to concentrations of papaver ranging from 1 x 10(-5) to 1 x 10(-3) M for 4 to 24 hr. Cytotoxicity was evaluated by enzyme leakage (lactate dehydrogenase) and by energy status of the cells (ATP/ADP). The role of biological reactive intermediates in the toxicity of papaver was investigated by measuring changes in cellular reduced glutathione levels (GSH), by inhibiting GSH synthesis, and by determining the production of lipid peroxidation (LPX). Papaverine produced concentration- and time-dependent increases in enzyme leakage, with significant effects occurring by the 8-hr exposure period. Pretreatment with SKF-525A or benzyl imidazole increased enzyme leakage induced by papaver especially at a later time frame (24 hr), but pretreatment with phenobarbital delayed the onset of cytotoxicity from 8 to 12 hr. Decreases in GSH levels paralleled the time course of enzyme leakage. However, the administration of buthionine sulfoximine to cell cultures dramatically decreased the time by which papaver induced cellular injury (2 hr vs 8 hr). Changes in cellular energy status (ATP/ADP) were also detected earlier than enzyme leakage (4 hr vs 8 hr). In contrast, no significant production of lipid peroxidation was noted in papaver-treated cultures. We suggest that the mechanism of papaver-induced hepatotoxicity may be related to alterations in glutathione balance of the cells and to disruption of energy homeostasis.
Adenosine Diphosphate↗
The possible role of glutathione on the hepatotoxic effect of papaverine hydrochloride in vitro.
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Animals↗
A primary culture system of adult rat heart cells for the study of toxicologic agents.
Tricyclic antidepressants (TCAs) are currently used in the treatment of mental depression and nocturnal enuresis. Clinically, these drugs are useful; however, cardiotoxicity can occur even with therapeutic dosages. For example, TCAs are known to alter myocardial function, induce arrhythmias, and produce heart block in individuals with a normal cardiovascular history. The present study was undertaken to establish a culture system of spontaneously contracting adult primary myocardial cells for toxicologic testing and to examine their contractility, morphology, and lactate dehydrogenase release (LDH) after treatment with one of the most cardiotoxic TCAs, amitriptyline. Primary myocardial cell cultures were obtained from approximately 60- to 90-day-old Sprague-Dawley rats. After the cells had been grown in culture for 11 days, they were treated with amitriptyline (1 x 10(-3), 1 x 10(-4), and 1 x 10(-5) M) for 2 to 24 h. The highest concentration of amitriptyline (1 x 10(-3) M) completely destroyed the cardiac muscle cells. In addition to moderate and severe vacuole, granule, and pseudopodia formation, all contractile activity was inhibited as early as 2 h after exposure to the intermediate concentration of 1 x 10(-4) M amitriptyline. Significant LDH release did not occur until 8 h after treatment with this intermediate concentration. Even though there was no significant LDH release at all 3 time points tested, there was a 50% decrease in beating activity (154 +/- 9 to 77 +/- 5 beats/min) and initiation of vacuole formation by 2 h with the lowest concentration of amitriptyline (1 x 10(-5) M). This study presents a new apparatus for the isolation of adult cardiac myocytes for the establishment of primary cell cultures for toxicologic testing. Furthermore, these data demonstrate that amitriptyline induces a concentration- and time-dependent cardiotoxic profile in a model of spontaneously contracting adult cardiac muscle cells in culture.
Amitriptyline↗
Dithranol-induced cytotoxicity in primary cultures of rat epidermal keratinocytes. I. The role of reactive oxygen species.
Primary cultured rat epidermal keratinocytes were used as an experimental model to detect oxidant-mediated adverse effects of dithranol (anthralin), a widely used antipsoriasis drug with tumor-promoting and skin-irritating properties. Keratinocytes were isolated and prepared from the skin of neonatal rats by a trypsin flotation method. Highly proliferative monolayer cells cultured in a serum-free medium were exposed to the test compound at concentrations (5-100 microM) used therapeutically for the treatment of skin disorders. Cytotoxicity was evaluated by changes in plasma membrane integrity (lactate dehydrogenase leakage), lysosomal function (neutral red uptake), and mitochondrial metabolic activity (reduction of 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide, MTT). Exposure of keratinocytes to dithranol produced time- and concentration-related toxic responses. MTT reduction was found to be a more sensitive endpoint of cytotoxicity, showing significant toxic effects at 2 hr, while significant leakage of lactate dehydrogenase did not result until 6 hr. Oxygen consumption in keratinocytes and isolated mitochondria showed a similar pattern after exposure to dithranol. Increased cyanide-insensitive respiration was also noted. Oxidative stress, measured by superoxide anion-dependent reduction of nitroblue tetrazolium, occurred before dithranol produced cytotoxicity in the keratinocyte cultures. Superoxide formation, which increased with time after dithranol exposure, was detected both extracellularly and intracellularly and was inhibited by the addition of superoxide dismutase. Dithranol-induced cell injury was partially prevented by treatment with superoxide dismutase, and greater protection was shown by concurrent treatment with superoxide dismutase plus catalase. These findings suggest that the superoxide anion and hydrogen peroxide may be involved in the cytotoxicity of dithranol and that a culture system of rat keratinocytes may be useful in evaluating the mechanism of toxicity of dermatotoxicants.
Animals↗
Mitochondrial regulation of superoxide by Ca2+: an alternate mechanism for the cardiotoxicity of doxorubicin.
Mitochondrial Ca2+ accumulation and the formation of reactive oxygen species are processes dependent on the electron transport system. The production of superoxide by respiring rat heart mitochondria was decreased by either chelating extramitochondrial Ca2+ with EGTA or by blocking mitochondrial Ca2+ uptake with ruthenium red. Mitochondrial experiments with doxorubicin showed an enhanced stimulation of reactive oxygen species, which was also inhibited by EGTA or ruthenium red. Myocardial cell cultures treated with doxorubicin showed an enhanced formation of intracellular reactive oxygen species, which preceded cell damage. Ruthenium red not only attenuated the enhanced formation of intracellular reactive oxygen species, but also increased cell viability. The relationship between mitochondrial Ca2+ transport and the formation of superoxide suggests that a disruption in mitochondrial Ca2+ homeostasis by doxorubicin may be involved in the release of reactive oxygen species and its cardiotoxicity.
Animals↗
Effects of maternal calorie-restricted diet on development of the foetal heart, as evaluated in primary cultures of rat myocardial cells.
Very-low-calorie diets have been implicated in causing ventricular arrhythmias and sudden cardiac death. Furthermore, studies indicate that maternal carbohydrate-restricted diets consumed during pregnancy and lactation reduce foetal growth, parturition and postnatal survival of rat pups. In this study, Sprague-Dawley rats were maintained on a semi-purified full-calorie or 50% carbohydrate-calorie-restricted diet throughout pregnancy. The function and integrity of myocardial cell cultures obtained from 3-5-day-old offspring from both groups of dams were evaluated after a drug-induced toxic challenge. After the myocytes had been in culture for 4 days, they were exposed to various concentrations of amitriptyline (1 x 10(-3) to 1 x 10(-5) M). Morphology, beating activity, lactate dehydrogenase release, glucose utilization, beta-adrenergic receptor [125I]iodopindolol binding, and cellular adenosine triphosphate content were evaluated for 24 hr after drug exposure. There were no significant differences in morphology, beating activity or glucose utilization between the full-calorie and calorie-restricted groups. When compared with the full-calorie group, lactate dehydrogenase release from the calorie-restricted group was significantly lower at 8 hr for the untreated controls and those cells exposed to 1 x 10(-4) and 1 x 10(-5) M-amitriptyline. Adenosine triphosphate levels were lower in untreated controls from the calorie-restricted group when compared with the full-calorie group at 4 hr. Within the calorie-restricted group, those cultures exposed to 1 x 10(-4) M-amitriptyline had significantly depressed adenosine triphosphate levels after 8 hr of drug treatment when compared with their respective untreated controls. Finally, the calorie-restricted group had significantly increased binding affinities of beta-receptors. Thus, maternal consumption of calorie-restricted diets during pregnancy may affect the myocardial functional capacity and integrity of the offspring.
Adenosine Triphosphate↗
In vitro metabolism and toxicity assessment of N-methylcarbazole in primary cultured rat hepatocytes.
N-Methycarbazole (NMC), a carcinogen and mutagen in tobacco smoke, was converted to two major metabolites by primary cultured rat hepatocytes as measured by high performance liquid chromatography (HPLC): N-hydroxymethylcarbazole (NHMC) and carbazole. These two metabolites had comparable retention times and identical ultraviolet spectra as those of reference standards. Identical retention times and mass spectra were also observed as detected by gas chromatography-mass spectroscopy (GC-MS) for NHMC and its reference standard. The toxicities of NMC and its two metabolites were assessed by lactate dehydrogenase (LDH) leakage and neutral red (NR) uptake. The rank order of cytotoxicity of NMC and its metabolites was found to be: NHMC greater than NMC greater than carbazole. Thus, we conclude that the hydroxylation of NMC to NHMC may represent a toxification step, while the further dealkylation to carbazole is most likely a detoxication process.
Animals↗
The cytotoxicity of p-chloro-m-xylenol in primary culture of rat hepatocytes.
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Animals↗
[Trials of acute treatment with SMS 201-995 in acromegalics].
The results of two acute treatment tests using SMS 201-995 (SMS), over a 24 hour period in acromegalic patients are presented. Test number 1: Seventeen cases with a mean age of 44.3 +/- 11.9 (21/71) years with an evolution of 9.2 +/- 6.5 (2/20) years and GH of 30.1 +/- 21.1 (5.2/96.4) ng/ml were treated with 50 micrograms/8 hours (8, 16, and 24 hours) of subcutaneous SMS. Test number 2: 26 cases with a mean age of 45.5 +/- 15.5 (21/71) years with an evolution of 9.1 +/- 7.9 (2/35) years and GH of 28.6 +/- 22.2 (5.2/96.4) ng/ml were treated with 100 micrograms/8 hours (8, 16, and 24 hours) of subcutaneous SMS. Ten point GH profile in 24 hours is evaluated in both tests and in number 2 insulin and blood sugar levels are measured at the same time points. In both tests GH is significantly reduced being the 100 micrograms/8 hour treatment schedule more efficient. The results in the decrease of GH in test number two are related to those obtained using SMS in prolonged treatments. Inspire of the reducing effect that SMS has on insulin levels, its influence on the blood sugar profile is scare.
Acromegaly↗
[Results of trans-sphenoidal surgery for the treatment of acromegaly].
UNLABELLED: During the past 17 years (1972-89) 55 transsphenoidal surgery (TSS) interventions were performed in our Hospital in 53 cases of acromagaly (2 cases underwent surgery twice). RESULTS: 22 were cured (40%); 15 partial efficacy (27%) and 18 negative efficacy (33%). Mean GH values (ngr/ml) before surgery were: Cured cases 15.8 + 12.9 (p = 0.0015). Basal GH values above 40 ngr/ml obscure the prognosis of TSS in acromegaly. Cure was perfectly achieved in smaller size hypophysis adenomas (Hardy Grade land 11 in CT scan). The complications in the early post-surgery were rare and transient. Chronic sequelae due to TSS occurred in 7 cases (13.5%), as complete or partial anterior hypophysis failure. TSS is the treatment of choice of acromegaly in our environment, however a significant number of cases do not achieve cure and need to complete treatment with hypophyseal radiotherapy.
Acromegaly↗
Failure of gentamicin to elevate cellular malondialdehyde content or increase generation of intracellular reactive oxygen species in primary cultures of renal cortical epithelial cells.
The role of lipid peroxidation in gentamicin cytotoxicity was assessed in primary cultures of renal cortical epithelial cells. The cellular content of malondialdehyde (MDA), one of the end products of lipid peroxidation, was determined, and the intracellular generation of reactive oxygen species, one of the events commonly occurring at the beginning of the process of lipid peroxidation, was estimated. Exposures to gentamicin were chosen that preceded or accompanied overt toxicity. MDA was determined by the thiobarbituric acid reactive substances assay. Intracellular generation of reactive oxygen species was estimated by quantitating the fluorescence of 2',7'-dichlorofluorescein (DCF'), a fluorophore formed by the reaction of the deacetylation product (2',7'-dichlorofluorescein, DCF) of the fluorescent probe 2',7'-dichlorofluorescein diacetate (DCFDA) with reactive oxygen species. Neither elevated MDA content nor intracellular generation of reactive oxygen species was observed in primary cultures of renal cortical epithelial cells treated with gentamicin, using exposures which preceded or accompanied overt toxicity. We conclude that lipid peroxidation does not play a role in gentamicin cytotoxicity.
Animals↗