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At least 721 records · Page 40Linked to original sources
PubMed1999

Immunomodulative effects of some drugs of abuse on human peripheral blood lymphocytes.

The cytotoxic effects of opiates, cocaine and their metabolites on peripheral blood mononuclear cells from healthy volunteers, concerning cell viability, were studied in a wide range of concentrations (ranging from 10-(2) to 10-(8) M), by 2 colorimetric in vitro assays, the neutral red uptake assay and thiazolyl blue tetrazolium bromide assay. All tested drugs of abuse and their metabolites were non-cytotoxic at concentrations lower than 10-(5) M. The possible immunomodulative effects of these substances were evaluated through phytohemagglutinin-induced lymphocyte proliferation ([3H]-thymidine DNA incorporation assay) as well as by a 51Cr release natural killer assay. The results showed immunomodulative effects of all the opiates tested. Cocaine, freebase cocaine and benzoylecgonine produced a statistically non-significant decrease of phytohemagglutinin proliferation. Cocaine induced a statistically non-significant increase, whereas freebase cocaine and benzoylecgonine showed a non-significant decrease of natural killer cell activity.

Adult↗
PubMed1998

Evaluation of the toxicity of guarana with in vitro bioassays.

A natural stimulant, Paullinia cupana, commonly called guarana, was tested for its ability to induce in vitro toxicity in Chinese hamster ovary (CHO) cells and bacterial cells (Photobacterium phosphoreum). The cytotoxic effects of aqueous guarana extracts were evaluated by three endpoint systems: neutral red (NR) uptake assay, total protein content [kenacid blue (KB)] assay, and tetrazolium (MTT) assay. The Microtox test was also used. Results indicated that the lowest concentration of guarana tested was not toxic and that the IC50 values calculated with the NR, KB, and MTT assays were lower than the highest concentration tested (40 mg/ml). There was no significant difference in cytotoxicity between the three test systems. The EC50 values obtained with the Microtox assay were consistent with these data. The present in vitro analysis suggests that the concentration of guarana is of critical importance in its cytotoxic activity and high doses could be harmful to human health.

Animals↗
PubMed1989

[Changes in the pH of leukocyte granules during the storage of preserved donor blood].

Data are presented on pH values in lymphocyte and neutrophil granules, as well as parameters of fluctuating pH changes in individual granules at early terms of storage (up to 72 h), evaluated by cytophotometry with the use of the vital stain neutral red in microspectrophotometer (Univar Reichert, Austria). An average value of pH in donor neutrophil granules was 6.57-0.12 (range 6.21-7.02). At day 3 of storage it decreased at average by 0.18 pH units. Rhythmical changes of pH in individual granules with pH 0.2-0.44 were found on all days of storage. The period of the rhythm lengthened from 3 min on day 1 to 4 min on day 3. This shift as well as acidification of granules during storage reflects their functional deterioration. The storage did not affect pH values in lymphocyte lysosomes which at average were 6.4, 6.5 and 6.35 on days 1, 2 and 3, respectively.

Adult↗
PubMed1992

The mechanism of Hg2+ toxicity in cultured human oral fibroblasts: the involvement of cellular thiols.

To study amalgam-related toxicity in a primary target cell type, human oral fibroblasts were grown in a low-serum medium containing 1.25% fetal bovine serum and exposed to Hg2+, a corrosion product of amalgam. A 1-h exposure to various concentrations of Hg2+ resulted in a dose-dependent loss of colony forming efficiency. Removal of the low-molecular-weight thiol cysteine from the medium increased the toxicity of Hg2+ almost 50-fold in comparison with complete medium or medium without fetal bovine serum. Accordingly, fetal bovine serum was not found to contain detectable levels of low-molecular-weight thiols. The levels of cellular free protein thiols were shown to be depleted Hg2+ at significantly lower concentrations of the metal ion than those required to decrease the levels of the major cellular low-molecular weight thiol glutathione. These decreases were dependent on the exposure conditions, i.e. the presence of serum and thiols, in a manner similar to the effect on colony forming efficiency. Other functions commonly related to cell viability, including the accumulation of the vital dye neutral red, the cytosolic retention of deoxyglucose and the mitochondrial reduction of tetrazolium were also inhibited by Hg2+, albeit at higher concentrations. Finally, the depletion of cellular glutathione, by pre-exposure of the cells to the glutathione synthesis inhibitor buthionine sulfoximine, somewhat increased the toxicity of Hg2+ and potentiated the depletion of protein thiols. Taken together, the toxicity of Hg2+ in human oral fibroblasts was demonstrated in several assays of which colony forming efficiency was the most sensitive, cell killing by this agent was related to its high affinity for protein thiols, whereas glutathione showed a significant, but limited, ability to protect the cells from Hg2+ toxicity.

Buthionine Sulfoximine↗
PubMed1991

2,3,7,8-Tetrachlorodibenzo-p-dioxin causes unbalanced growth in 5L rat hepatoma cells.

5L cells, dedifferentiated descendents of the rat hepatoma line H4IIEC3, constitute one of the rare continuous lines which are sensitive to the toxic effects of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In the present study we investigated the nature of TCDD toxicity in these cells. The following results were obtained: (1) Exposure to 0.1 nM TCDD for 48 hr inhibits the proliferation of 5L cells by more than 50%, as determined by the increase in the number of cells and the amount of DNA per culture. (2) TCDD doubles the amount of protein and the uptake of neutral red per cell during the 48-hr exposure period. (3) TCDD restores neither constitutive levels of tyrosine aminotransferase, a marker of liver-specific functions, nor its inducibility by dexamethasone. (4) The effects of TCDD are reversible when TCDD-containing growth media are replaced by TCDD-free medium. (5) 5L cells grown at 2% of fetal bovine serum are considerably more sensitive to TCDD than those grown at 10% serum. These results indicate that TCDD inhibits the proliferation of 5L cells without retarding the rate of growth or overtly changing the status of differentiation. The dioxin possibly causes unbalanced cell growth by interfering with the action of hormones or factors contained in the growth medium.

Animals↗
PubMed1993

In vitro cytotoxicity of 1,4-naphthoquinone derivatives to replicating cells.

The acute cytotoxicities of a series of alkyl-1,4-naphthoquinones (NQ) and of 2-hydroxy-3-alkyl-1,4-NQs, as well as some amino derivatives, were evaluated with the neutral red cytotoxicity assay, using BALB/c mouse 3T3 fibroblasts. As compared to the unsubstituted 1,4-NQ: (i) Substitution at the 2 position reduced toxicity, with the extent of reduction following the sequence, hydroxyl >> dimethylamino >> C1-C5 alkyl group. (ii) Substitution with C2-C5 alkyl groups at position 3 enhanced toxicity. As noted with the n-alkyl-1,4-NQs, increasing the chain length of the 2-hydroxy-3-alkyl-1,4-NQs did not appreciably change potency of the test agent. (iii) Substitution with amino groups at position 3 had little effect on cytotoxicity. Some differences in cytotoxicity of specific test agent were noted between the 3T3 fibroblasts and isolated rat hepatocytes, as reported in the literature.

3T3 Cells↗
PubMed2006

A cell-based luminescence assay is effective for high-throughput screening of potential influenza antivirals.

The spread of highly pathogenic avian influenza across geographical and species barriers underscores the increasing need for novel antivirals to compliment vaccination and existing antiviral therapies. Identification of new antiviral lead compounds depends on robust primary assays for high-throughput screening (HTS) of large compound libraries. We have developed a cell-based screen for potential influenza antivirals that measures the cytopathic effect (CPE) induced by influenza virus (A/Udorn/72, H3N2) infection in Madin Darby canine kidney (MDCK) cells using the luminescent-based CellTiter Glo system. This 72 h assay is validated for HTS in 384-well plates and performs more consistently and reliably than methods using neutral red, with Z values>0.8, signal-to-background>30 and signal-to-noise>10. In a blinded pilot screen (n=10,781) at 10 microM concentration, four compounds (with previously demonstrated efficacy against influenza) inhibited viral-induced CPE by >50%, with EC50/CC50 values comparable to those determined by other cell-based assays, thereby validating this assay accuracy and ability to simultaneously evaluate compound cellular availability and/or toxicity. This assay is translatable for screening against other influenza strains, such as avian flu, and may facilitate identification of antivirals for other viruses that induce CPE, such as West Nile or Dengue.

Animals↗
PubMed1994

Electron microscopic studies on the formation of renal juxtaglomerular cell granules in the vitally stained mouse kidney.

Mouse renal juxtaglomerular cells (JGC) were vitally stained with neutral red, and then fixed with glutaraldehyde to study by electron microscopy. Ultrastructural observation showed a large number of characteristic low electron dense juxtaglomerular granules (JGG) or low dense granules (LDG) in the cytoplasm of JGC. Many LDG contained a flocculent material with a dense core, which was as dense as the contents of JGG. Two kinds of LDG were observed. One of LDG was surrounded by single membrane and partial membrane, and another was surrounded by double membranes. Some LDG did not contain electron dense flocculent material. LDG were surrounded by rough endoplasmic reticulum (r-ER). Alteration of Golgi apparatus and r-ER was observed in JGC. Golgi complex did not associate with JGG and LDG.

Animals↗
PubMed1996

Changes in antioxidative activities induced by Fe (II) and Fe (III) in cultured Vero cells.

The toxicity of iron (II) and iron (III) chlorides was studied at different biochemical and cellular levels, including antioxidative and metabolic enzymes and two general indicators of cytotoxicity in Vero monkey kidney cells after 24-h exposure. Iron (II) was fourfold more toxic than Fe (III) in cell proliferation, with EC50 of 5.5 and 22 mM, respectively. Metabolic markers were far more sensitive than cytotoxicity assays at these concentrations. At the highest concentrations of toxicant tested [10 mM Fe(II) and 50 mM Fe(III)], both species produced nearly total inhibition of the relative uptake of neutral red (RNRU) and phosphofructokinase activity (PFK), and stimulated intracellular specific lactate dehydrogenase activity (LDH). Succinate dehydrogenase (SDH) and hexosaminidase (HEX) activities were reduced in dose-dependent manner, as was the antioxidative enzyme glucose-6-phosphate dehydrogenase (G-6-PDH) with both forms of iron. Glutathione reductase (GOR) and glutathione-S-transferase (GST) activities were stimulated by Fe (II) but were inhibited by the higher Fe (III) concentrations. In conclusion, the experimental model may be useful for the study of different metabolic effects induced by the two oxidation states of iron.

Animals↗
PubMed2002

Differential in vitro hepatotoxicity of troglitazone and rosiglitazone among cryopreserved human hepatocytes from 37 donors.

We report here our studies on troglitazone and rosiglitazone cytotoxicity in human hepatocytes isolated from multiple donors to investigate factors responsible for individual differences in sensitivity to the known hepatotoxicity of these antidiabetic drugs. Using cellular adenosine triphosphate (ATP) content as an endpoint, cytotoxicity of both drugs was evaluated in cryopreserved human hepatocytes from 37 donors. We confirmed reports of others that troglitazone was cytotoxic to human hepatocytes using cellular ATP content as an endpoint. In addition, we found that rosiglitazone, although less toxic in the study population, was cytotoxic to hepatocytes in some donors (EC(50)<100 microM). ATP content, 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) metabolism, depletion of intracellular glutathione, Alamar Blue metabolism, and neutral red uptake were used as endpoints in a single donor study using freshly isolated human hepatocytes. Troglitazone appeared to be more toxic than rosiglitazone by all endpoints. From the demographic data provided to us for each donor, we were able to establish no direct correlation between cytotoxicity (expressed as EC(50) values) and age, sex, smoking status, or alcohol consumption. We conclude that troglitazone and rosiglitazone are differentially toxic to human hepatocytes, and that toxicity may be independent of age, sex, tobacco use, and alcohol use.

Adenosine Triphosphate↗
PubMed2001

Polyamide 6 composite membranes: properties and in vitro biocompatibility evaluation.

The aim of the present study was to develop polyamide 6 membrane blended with gelatin and chondroitin sulfate using the phase precipitation method and evaluate its in vitro biocompatibility. Morphology of membranes was studied by laser scanning confocal microscopy which allowed the nondestructive visualization of internal bulk morphology of membranes. Membranes exhibited porous morphology with pores spanning across the membrane width with interconnections at various depths. Membranes showed adequate mechanical properties with tensile strengths of 20.10 +/- 0.64 MPa, % strain of 3.01+/-0.07, and modulus of 1082.50+/-23.50 MPa. In vitro biocompatibility of membranes by direct contact test did not show degenerative effects on NIH3T3 cells and also its leach-out products (LOP), as determined by tetrazolium (MTT) and neutral red uptake (NRU) assay. Mouse peritoneal macrophage cultured in contact with membranes and PTFE control showed comparable expression of activation markers such as CD11b/CD18, CD45, CD14, and CD86 suggesting the membranes' non-activating nature. Membrane LOP did not induce excessive proliferation of mouse splenocytes suggesting its non-antigenic nature. Preliminary blood compatibility of membranes was observed with no detectable hemolysis in static incubation assay. Taken collectively, the present data demonstrate that polyamide 6 composite membranes are biocompatible and prospective candidates for tissue engineering applications.

3T3 Cells↗
PubMed2001

Triphenyltin acetate-induced cytotoxicity and CD4(+) and CD8(+) depletion in mouse thymocyte primary cultures.

Organotin compounds (OTs) find application worldwide as catalysts, stabilizers and biocides. Triphenyltin derivatives (TPs), including the fungicide triphenyltin acetate (TPTA), are OTs mostly used in our country. Some OTs were proved to be immunotoxic and in this paper the cytotoxicity, the possible selective activity upon definite lymphocyte subsets as well as the antiproliferative effect of TPTA was investigated in vitro by using primary cultures of mouse thymocytes. TPTA (5, 10 and 25 microM) was cytotoxic to these cells, as demonstrated by the significant (P<0.05) reduction of the cell viability percentage (trypan blue dye exclusion test), the neutral red uptake and the reduction of tetrazolium salts to formazan products (MTT assay). These overt effects were already noticed after 4 h of exposure to TPTA. The fungicide otherwise significantly reduced, after 24 h of incubation, the percentage of mature single positive thymocytes, particularly the CD4(+)/CD8(-) one. Finally, a significative dose-dependent inhibition of the T-cell mitogen-induced cell proliferation was observed in thymocytes exposed to 1 and 8 microM TPTA. These results are indicative of the TPTA immunotoxic properties, according to previous published reports concerning the in vitro and in vivo toxicity of some di- and triorganotin compounds.

Animals↗
PubMed1992

The combined effects of cocaine and amphetamine on primary postnatal rat heart cell cultures.

Recent reports demonstrated that perinatal exposure to cocaine (Coc) and amphetamines (Amph) predisposed the infant to adverse cardiovascular consequences. Dose- and time-dependent effects of Coc and Amph on postnatal rat myocardial cell cultures are described. Contractile activity, morphology, lactate dehydrogenase (LDH) release, MTT formazan production, and neutral red (NR) retention were determined. No contractile activity was observed in cultures treated with the highest drug doses. After 24 h, the percentage of areas exhibiting contractile activity was decreased in cultures exposed to the lowest doses of both drugs. When Coc and Amph were combined, beating rates were significantly altered. Morphologic alterations were observed in all treatment groups. LDH release occurred in cultures exposed to the highest doses of both drugs. No significant differences were observed for MTT or NR. These data demonstrate that Coc and Amph doses > or = 1 x 10(-5) M induce adverse effects on morphology and contractile activity of postnatal myocardial cell cultures.

Amphetamine↗
PubMed2005

Exposure of bronchial epithelial cells to whole cigarette smoke: assessment of cellular responses.

Cigarette smoke is composed of approximately 5% particulate phase and 95% vapour phase by weight. However, routine in vitro toxicological testing of smoke normally only measures the activity of the particulate phase. This study describes a new system for exposing cells at an air-liquid interface to serial dilutions of gaseous smoke. Confluent monolayers of NCI-H292 human lung epithelial cells on semipermeable membranes were placed in a purpose-designed Perspex chamber at an air-liquid interface. The cells were exposed to dilute whole mainstream cigarette smoke for 30 minutes, followed by a 20-hour recovery period. Firstly, high and low delivery cigarettes were compared, and cytotoxicity was determined by using the neutral red uptake assay. Clear differential cytotoxic responses were observed with the two cigarette types, which correlated positively with the concentrations of components in smoke, and particularly compounds in the vapour phase, such as aldehydes. Secondly, low doses of smoke were found to up-regulate mRNA levels of the secreted mucin, MUC5AC, and to stimulate the production of interleukin (IL)-6, IL-8 and matrix-metalloprotease-1, but had no effect on growth-related oncogene alpha. This system will facilitate further investigations into the toxicological mechanisms of cigarette smoke components, and may be useful for studying other gaseous mixtures or aerosols.

Adenocarcinoma↗
PubMed1982

Some observations on the mechanisms of blocking of nuclear staining by cisplatin.

The effect of cisplatin (cis-dichloro-diamminoplatinum II) treatment on staining of nuclei with various basic dyes and with the Feulgen reaction has been studied. Although cisplatin is reported to show negligible reaction with DNA phosphates, it hs a substantial blocking effect on staining with most dyes. Short treatment with cisplatin results in binding mainly to guanine bases of DNA, causing partial blocking of the Feulgen reaction and almost complete blocking of ethidium intercalation; binding of neutral red and crystal violet is enhanced, apparently as a result of cisplatin-induced denaturation of DNA. Very prolonged cisplatin treatment does not completely block the Feulgen reaction, indicating that reaction of cisplatin with purine bases is not complete. Since attachment of cisplatin to DNA bases is unlikely to prevent binding of most basic dyes, it is suggested that the blocking of their staining may result from steric hindrance caused by formation of DNA-protein cross-links by cisplatin. Whatever the mechanism, it is incapable of producing complete blocking of staining with certain dyes. As a practical tool, it appears that rapid and almost complete blocking of staining by cisplatin may be used as an indicator of intercalative binding of dyes to DNA.

Cell Nucleus↗
PubMed2003

Possibilities of chromoesophagoscopy for diagnosis of Barrett's esophagus.

When the distal esophagus is covered with columnar gastric mucosa up to 2 cm from the esophagogastric junction it is considered normal. If the distal esophagus is covered with columnar epithelium more than 2 cm from the esophagogastric junction, it is called Barrett's esophagus. We have developed a new chromoesophagoscopic method to improve diagnostic testing for Barrett's esophagus. The distinctive feature of this method is that 4 to 5 ml of a 1% solution of neutral red is administered intravenously, after which excretion of the stain by the esophageal mucosa is examined by endoscopy. Chromoesophagoscopy has been carried out in 11 patients with reflux esophagitis. It revealed Barrett's esophagus in four patients, which was proved by histologic evaluation of biopsy specimens obtained from the stained zone of the esophageal mucosa. These observations suggest that chromoesophagoscopy is an effective, accessible, feasible, safe method for diagnosing Barrett's esophagus. It allows us to determine the length of the metaplastic epithelium and the topography of gastric glands; it also allows us to examine parietal cells in the esophagus and estimate the functional activity of these parietal cells in metaplastic epithelium.

Adult↗
PubMed1998

Differences in the measurement of cytotoxicity of complex mixtures with rainbow trout hepatocytes and fibroblasts.

The purpose of this study was to compare cytotoxicity tests for industrial/municipal wastewaters using two different cell systems: rainbow trout hepatocytes and gonadal fibroblasts. They were exposed to concentrations of industrial/municipal wastewaters for 48 h at 15 degrees C. In addition, wastewater toxicity was evaluated concurrently with the 96-h rainbow trout acute lethality bioassay. Hepatocyte viability was assayed with the propidium iodide (PI) exclusion and neutral red (NR) uptake inhibition tests, while gonadal fibroblast viability was assayed with the NR uptake test. The results show that hepatocyte viability measurement by the PI exclusion test and NR uptake are in agreement with complex mixture exposures. Moreover, cytotoxicity was correlated with trout mortality for most of the effluents (80%). Although a low correlation was found between the trout fibroblast and the hepatocyte NR uptake assays, the NR uptake assay using gonadal fibroblasts was correlated with trout mortality, but in only 60% of the samples tested. Hepatocyte cytotoxicity data, whether determined by the PI exclusion test or the NR uptake test, appeared to be more strongly associated with trout toxicity than did the rainbow trout gonadal fibroblasts, in the case of complex environmental mixtures.

Animals↗
PubMed1980

The relative time course of early changes in mitochondrial function and intracellular pH during hypoxia in the isolated toad ventricle strip.

Changes in the intracellular H+ ion concentration (pHi) and in the oxidation-reduction state of the respiratory chain were measured spectrophotometrically in the isolated ventricle strip from the toad (Bufo marinus). The relative time course of the delta pHi as indicated by changes in light absorption of the pH dye neutral red, cytochrome c, and peak isometric twitch tension were compared during transient hypoxic episodes. The first detectable change in pH occurred 4.5 minutes after the peak twitch tension began to decrease with the onset of hypoxia. The initial decrease in tension and reduction of cytochrome c occurred at a similar time prior to the change in pHi. On reoxygenation, cytochrome c rapidly became oxidized, and the pHi and tension recovered more slowly. During acidification by increasing superfusate PCO2, pHi and tension decreased together, and cytochrome c did not change significantly. Thus, although changes in pHi do affect mechanical performance, these results show that mechanical dysfunction pursuant to hypoxia is not directly attributable to intracellular acidification.

Animals↗