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At least 1,225 records · Page 68Linked to original sources
PubMed2000

In vitro inhibitory effects of antioxidants on cytotoxicity of T-2 toxin.

T-2 toxin is a secondary fungal metabolite produced by various species of Fusarium. It is capable of killing cells by causing extensive damage to the cellular membrane. In this study, cytotoxicity of T-2 toxin in combination with different antioxidant materials, including vitamin C (vit. C), vitamin E (vit. E) and selenium (sel) was investigated in vitro using the neutral red cytotoxicity assay. Eleven primary and transformed cell lines established from different tissues were used in pre-test experiments to identify the most sensitive and resistant lines by measuring the half lethal concentration (LC(50)) of the toxin. Three cell lines including human gingival fibroblast (HGF), the most sensitive (LC(50)=0.25 ng/ml), human colorectal adenocarcinoma (SW742), the most resistant (LC(50)=5.5 ng/ml) and human hepatoma (HepG2), with median susceptibility (LC(50)=2 ng/ml) were selected to investigate the inhibitory effects of the antioxidant agents, on cytotoxicity of T-2 toxin. Our results demonstrated that co-incubation of cell lines with different concentrations of T-2 toxin and antioxidants decreased significantly, but did not totally inhibit, the cytotoxicity of T-2 toxin (P<0.001). These findings suggest that in addition to lipid peroxidation, which is inhibited by antioxidants, other unidentified mechanism(s) seem to be involved in cytotoxicity of T-2 toxin.

Antioxidants↗
PubMed1998

Ability of 16 priority PAHs to be directly cytotoxic to a cell line from the rainbow trout gill.

Sixteen polycyclic aromatic hydrocarbons (PAHs) were screened for their ability to be directly cytotoxic to a cell line from the rainbow trout gill, RTgill-W1. Exposure times of 2 h or less were sufficient for direct cytotoxicity to be detected, which appeared to be caused by a common mechanism, the general perturbation of membranes. This was judged by the similarity of results obtained for three fluorescent indicator dyes, alamar Blue, 5-carboxyfluorescein diacetate acetoxymethyl ester (CFDA-AM) and neutral red. Among the 16 PAHs tested, just two- and three-ring PAHs were found to be directly cytotoxic. These were naphthalene approximately = acenaphthylene approximately = acenaphthene > fluorene approximately = phenanthrene. The results suggest that water solubility and lipophilicity are the critical properties determining the direct cytotoxicity of PAHs and that they do so by influencing PAH accumulation in membranes. Only naphthalene was effective at concentrations well below its water solubility limit. Therefore, direct cytotoxicity is likely to be most environmentally relevant only with naphthalene.

Acenaphthenes↗
PubMed1998

Ability of 16 priority PAHs to be photocytotoxic to a cell line from the rainbow trout gill.

Sixteen polycyclic aromatic hydrocarbons (PAHs) were screened for their ability to be photocytotoxic to a cell line from the rainbow trout gill, RTgill-W1. PAHs could be divided into one of three groups: incapable of being photocytotoxic, able to be both photocytotoxic and directly cytotoxic, or capable of being only photocytotoxic. Photocytotoxicity was distinct from direct cytotoxicity in that EC50 values were lower with the neutral red assay immediately after the PAH/UV treatment than with alamar Blue or CFDA-AM, indicating a more specific action on lysosomes. As well, in photocytotoxicity but not in direct cytotoxicity, the three assays showed increased impairment 24 h after treatment. Most PAHs were found to be strictly photocytotoxic; however, only six compounds were photocytotoxic at concentrations theoretically achievable in water. When photocytotoxic PAHs were ranked relative to fluoranthene to establish fluoranthene equivalent factors (FEFs), benzo[a]pyrene and benzo[g,h,i]perylene were found to be most potent. However, when the water solubility of each compound was taken into account in order to calculate the potential environmental photocytotoxic potency (PEPP), fluoranthene and pyrene appeared to have the most potential to impact fish through photocytotoxicity.

Animals↗
PubMed1998

Evaluation of P19 cells for studying mechanisms of developmental toxicity: application to four direct-acting alkylating agents.

P19 cells are pluripotent murine embryonic carcinoma (EC) cells that can be induced by all-trans-retinoic acid (RA) to differentiate into cells that are biochemically and morphologically similar to cells of the central nervous system. We have established these cells as a reproducible cell system to evaluate potential effects of agents disrupting neuronal differentiation. The viability of P19 cells was assessed using a neutral red assay. Uptake of [3H]-gamma-amino butyric acid ([3H]GABA) was assessed as a marker of neuronal differentiation. We observed significant increases in [3H]GABA over time, corresponding with the appearance of cells with neuronal morphologies. 2,4-Diaminobutyric acid, a specific inhibitor of high affinity neuronal GABA uptake, reduced [3H]GABA uptake by approximately 75%. Additionally, [3H]GABA uptake in cells treated with dimethylsulfoxide (DMSO), which differentiate into mesodermal derivatives, was approximately 25% of uptake observed in RA-exposed, neuronally differentiated P19 cells. The morphology of P19 cell cultures correlated with [3H]GABA uptake: high [3H]GABA uptake was only observed in cultures with distinct neuronal morphologies. These results suggest that [3H]GABA uptake is a good indicator of neuronal differentiation in P19 cells. The responsiveness of P19 cells to developmental toxicants was assessed by comparing effects in P19 cells with effects observed previously in primary cultures of differentiating rat embryo midbrain (CNS) cells. Alkylating agents chosen for this investigation include methylnitrosourea (MNU), ethylnitrosourea (ENU), methyl methanesulfonate (MMS), and ethyl methanesulfonate (EMS). The rank order of potency of these alkylating agents in the CNS cells was MMS > MNU > ENU > EMS. With the exception of ENU, concentrations that caused effects on growth and differentiation in the P19 cells were very comparable to those causing similar effects in CNS cell cultures. Our results with P19 cells suggest that this EC cell line may also be a useful in vitro cell system for studying mechanisms of developmental toxicity, with the advantages of being an established cell line.

Alkylating Agents↗
PubMed1998

Adaptation to oxidative stress: effects of vinclozolin and iprodione on the HepG2 cell line.

It is well known that the dicarboximide fungicides, vinclozolin and iprodione, induce lipid peroxidation by means of oxygen activation in fungi, but their action on mammalian cells is not yet clear. We therefore investigated the effect of 1- and 24-h treatments with vinclozolin at concentrations of 25, 50, 100 microg/ml and iprodione at concentration of 62.5, 125, 250 microg/ml on malonaldehyde and free radical production and on reduced glutathione levels in the human HepG2 hepatoma cell line. The concentrations were chosen on the basis of neutral red cytotoxicity assays. One-hour treatment with the different concentrations of either vinclozolin or iprodione increased both malonaldehyde and free radical content, and decreased reduced glutathione levels, whereas 24-h treatment decreased malonaldehyde content and free radical production, and increased reduced glutathione concentration. These results suggest that the mammalian cells respond to the initial oxidative damage caused by the two dicarboximide fungicides by means of a characteristic adaptative phenomenon within 24 h. This hypothesis is supported by the antagonized effects caused by treatment with the two dicarboximide fungicides and buthionine sulfoximine 0.5 mM, a specific and irreversible inhibitor of reduced glutathione synthesis. The data confirm that the two dicarboximide fungicides maintain their specific action in mammalian cells, although this action is masked by adaptation.

Adaptation, Physiological↗
PubMed1998

Acute neural damage in the rat neocortex in vitro induced by a combination of anoxia and mechanical stress.

To elucidate the mechanisms of neural damage after brain ischemia, rat neocortical slices were exposed to anoxia at room temperature for 1 h, and other slices were prepared from the neocortical blocks exposed to anoxia at room temperature for 1 h. Field potentials elicited by the stimulation of layer IV were recorded in supragranular layers in these slices. No clear damage was observed electrophysiologically or morphologically in these slices. In contrast, a complete loss of the trans-synaptic field potentials and a decrease in the density of the cells stained with Neutral Red were elicited by injecting an anoxic medium into the neocortical blocks at room temperature for 1 h. In the slice preparations, the injection of the anoxic medium failed to reproduce clear neural damage, while a combination of mechanical stress and anoxia elicited a complete loss of trans-synaptic potentials; this was alleviated by Gd3+ (50 microM) and D(-)-2-amino-5-phosphonovaleric acid (100 microM). These results indicate that a combination of mechanical stress and anoxia produces acute and severe neural damage even at room temperature in vitro. The mechanism of the damage and the relationship between the neural damage in vitro and in vivo are discussed.

Animals↗
PubMed2000

Cytotoxicity of prodigiosin and benznidazole on V79 cells.

The cytotoxicity of prodigiosin, an antibiotic and potential trypanocide produced by Serratia marcescens, and Benznidazole, a trypanocidal drug, were assayed on V79 fibroblast cell line. Three independent endpoints for cytotoxicity were evaluated; namely, the nucleic acid content (NAC), MTT reduction and neutral red uptake (NRU). IC(50) values of 1-20 microM were obtained for prodigiosin in the NRU, MTT and NAC tests. Prodigiosin had greater trypanocidal activity (IC(50)=5 microM) than Nifurtimox (IC(50)=150 microM) a known trypanocide drug used in Chagas' disease therapy. Benznidazole was less toxic (IC(50)=2000 microM) than prodigiosin (IC(50)=1-20 microM) in V79 cells based on the MTT and NAC assays. Benznidazole stimulated the NRU until 2 mM. Indeed, the cell viability measured with the NRU was higher at all concentrations of benznidazole tested than that measured by MTT reduction and NAC assays.

Animals↗
PubMed1998

Toxic effects of several types of antifouling paints in human and rat hepatic or epidermal cells.

Fouling is the successive development of marine organisms on immersed surfaces, a process which has heavy negative economic impacts. Several antifouling technologies, generally based on the leaching of biocides from painted surfaces, have been developed, but these biocides are toxic to the environment. Hence, we compared the toxicity of several currently used paint lixiviats in rat hepatocytes, human HepG2 and HaCaT cells. Acute toxicity was assessed by the Neutral Red and MTT assays. Chronic effect was tested using induction of the 7-ethoxyresorufin-O-deethylase (EROD) activity as a marker. Large variations were observed among the various cell types or the antifouling formulations, both in terms of IC50 values (from approximately 0.5 to approximately 10%, v/v) and EROD induction (from approximately 1 to 10-fold over control). These differences appear to be related to variable biocide (copper compounds, organotins, etc...) concentrations in the different paint formulations, or to the specific metabolic capabilities of the cell system used.

Animals↗
PubMed1999

A comparison of the effects of verocytotoxin-1 on primary human renal cell cultures.

Infection with verocytotoxin-producing Escherichia coli causes haemolytic uraemic syndrome (HUS). Verocytotoxin-1 (VT1) is cytopathic to renal microvascular endothelial cells in culture, supporting the hypothesis that the vasculopathy of HUS is caused directly by the toxic action of VT1 on cells. We provide evidence that VT1 inhibits protein synthesis in primary cultures of glomerular epithelial cells (GE), cortical tubular epithelial cells (CTE) and mesangial cells (MC). Using 100 pg/ml of VT1 we saw a decrease in protein synthesis to 14.3+/-1.9% in vero cells (a primate cell line), 1.7+/-0.3% in GE, 0.9+/-0.4% in CTE and 74.8+/-1.3% in MC at 24 h. The human renal epithelial cells are at least as sensitive as vero cells to the protein synthesis inhibitory effects of VT1 if not more so. Cell viability decreased in all cultures as measured by MTT reduction, neutral red incorporation and lactate dehydrogenase release and followed the same pattern of susceptibility as for protein synthesis inhibition. However, unlike vero cells, death occurred without DNA fragmentation. Cell sensitivity was greatest in cells which bound more VT1.

Animals↗
PubMed2001

Screening of Yemeni medicinal plants for antibacterial and cytotoxic activities.

Ethanolic extracts of 20 selected plant species used by Yemeni traditional healers to treat infectious diseases were screened for their antibacterial activity against both Gram-positive and Gram-negative bacteria, as well as for cytotoxic activity. Fourteen of the ethanolic extracts showed variable degrees of antibacterial activity. The active ethanolic extracts were partitioned between ethyl acetate and water for a first separation. The ethyl acetate extract of Lawsonia inermis was found to be the most active one against all bacteria in the test system. Other promising results could be obtained from extracts of Aloe perryi, Indigofera oblongifolia, Meriandra benghalensis and Ziziphus spina christi. Additionally, the ethanolic extracts of the 20 plants under investigation were tested for their cytotoxic effects on FL-cells using the neutral red assay. Extracts of Calotropis procera, Chenopodium murale, Pulicaria orientalis, Tribulus terrestris and Withania somniferum displayed a remarkable activity.

Anti-Bacterial Agents↗
PubMed2001

Screening of various Swertia species extracts in primary monolayer cultures of rat hepatocytes against carbon tetrachloride- and paracetamol-induced toxicity.

Swertia chirata Buch-Ham. (Gentianaceae), one of the oldest medicinal herbs of India, is a source of the Indian ayurvedic drug 'chirata' used for the treatment of liver disorders and malarial fevers. In this study, eight species of Swertia were collected. Each of the dry whole plant was extracted into methanol, the aqueous extract of which was sequentially extracted into hexane, chloroform and butanol extracts. The extracts were screened for their anti-hepatotoxic activity against carbon tetrachloride (CCl4) and paracetamol (acetaminophen (AAP)) toxicity in primary monolayer cultures of rat hepatocytes. The primary cultures, 2.5 x 10(6) cells /3 ml medium/60 mm collagen-coated plates, were exposed to 2.5 mM CCl4 or 12 mM AAP in the presence or absence of plant extracts (100 microg/ml culture medium). Cells and medium were harvested after 22 h of treatment for the assay of cellular reduced gluthathione (GSH) content and leakage of lactate dehydrogenase as biological end-points of toxicity. Both CCl4 and AAP at the indicated concentrations reduced GSH by almost 50 and 80%, respectively, while the enzyme leakage was almost 15% above the untreated control. Hexane and methanol extracts of most of the species in general offered relatively good protection. The anti-hepatotoxic activity, nevertheless, was evident in all Swertia species against both the toxicants. However, Swertia purpurascens, Swertia chirata, Swertia paniculata and Swertia cordata exhibited better activity compared with other species investigated. In addition, influence of various extracts (10-100 microg/ml medium) was examined on cellular growth of rat Reuber hepatoma cell line H4IIEC3/G-. Except for the butanol extract of S. chirata, no other extracts exerted toxicity in terms of neutral red uptake by the cells.

Acetaminophen↗
PubMed2000

Tecoma sambucifolia: anti-inflammatory and antinociceptive activities, and 'in vitro' toxicity of extracts of the 'huarumo' of peruvian incas.

Aqueous and alcoholic extracts of pods and flowers of Tecoma sambucifolia H.B.K. (Bignoniaceae) ('huarumo') were analysed to determine their anti-inflammatory activity (carrageenan-induced edema test), antinociceptive activity (acetic acid writhing test) and 'in vitro' toxicity in Chinese hamster ovary cells, human hepatome cells and human larynx epidermal carcinoma cells. The cytotoxic effects of both extracts were evaluated by two endpoint systems: neutral red uptake assay and tetrazolium assay. The results showed that all extracts have anti-inflammatory and antinociceptive activity, but the highest potency is that of the alcoholic extracts. There were significant differences in cytotoxicity between extracts and among the response of cells to them. The highest cytotoxicity was noted with the alcoholic extract, and the human hepatome cell line was the most sensitive, especially to the alcoholic extract of flowers. The aqueous pod extract appeared to have the best pharmaco-toxicological profile, since it provided a significant reduction of both pain and inflammation together with the lowest cytotoxicity.

Animals↗
PubMed1996

Noradrenergic innervation of nasal polyps and polypoid mucosae.

In order to study the sympathetic innervation of nasal polyps and polypoid mucosae, the glyoxylic catecholaminergic histofluorescence method was employed in the examination of specimens taken from patients who had nasal disorders with polyps or polypoid mucosae. One percent neutral red was used as a counterstain. Abundant sympathetic fibers were present around the vessels of the pedicle of nasal polyps. However, no sympathetic innervation was found in the body and apex of the polyps. In the microscopical views of polypoid formations, there were no obvious differences between non-diseased nasal mucosa and polypoid mucosa in the distribution of sympathetic innervation. Based on these results, the following conclusions were drawn: (1) The loss of the sympathetic innervation was suggested to an important role in the pathogenesis of nasal polyps. (2) During polypectomy, the polyp had better be removed along with the pedicle for there is abundant sympathetic innervation and it will result in reduced bleeding.

Humans↗
PubMed2002

Effect of seabuckthorn on sodium nitroprusside-induced cytotoxicity in murine macrophages.

The present study reports the anti-oxidant activity of alcoholic extracts of leaf and fruit of seabuckthorn (SBT) on nitric oxide (NO) induced cytotoxicity in J-774 macrophages. Sodium nitroprusside (SNP), which generates NO at the concentration of 500 microg/ml, induced cytotoxicity as revealed by decreased neutral red uptake by macrophages. The cytotoxicity of SNP was attributed to enhanced reactive oxygen species (ROS) production, which in turn resulted in decrease in anti-oxidant levels. Alcoholic leaf and fruit extracts of SBT at the concentration of 500 microg/ml were found to have a significant cytoprotective effect against SNP-induced oxidative stress. These extracts inhibited SNP-induced cytotoxicity, free radical production and maintained the anti-oxidant status identical to that of control cells. The alcoholic fruit extract of SBT was found to have significantly higher anti-oxidant activity than leaf extract against SNP-induced cytotoxicity in murine macrophages.

Animals↗
PubMed2000

Alterations on polyamine content and glutathione metabolism induced by different concentrations of paraquat in CHO-K1 cells.

The effect of herbicide paraquat has been assessed on CHO-K1 cultures at different concentrations. Glutathione peroxidase, reductase and S-transferase, as well as total and oxidized glutathione, were evaluated along the standard growth curve of the cultures. Paraquat was then administered during mid-log phase at concentrations that produced a calculated lethality of 6.25%, 12.5% and 25%, using the lysosomal dye assay, neutral red. After 24hr of incubation with paraquat, glutathione peroxidase suffered a large dose-response increase, unlike glutathione reductase and S-transferase, the activities of which were lower than untreated controls. The profile of total glutathione content was similar to that found for glutathione peroxidase, increasing with the administered doses of the herbicide. Polyamine content has been also studied at the same concentrations of paraquat, showing that intracellular spermidine and spermine pools were negatively affected with paraquat in a dose-response manner, unlike putrescine, which maintained elevated pools at the three concentrations assayed.

Animals↗
PubMed2000

Comparison of an in vitro cellular phototoxicity model against controlled clinical trials of fluoroquinolone skin phototoxicity.

Many therapeutic drugs induce phototoxic skin responses following exposure to solar or artificial ultraviolet radiation sources. Several in vitro model systems have been developed to predict drug phototoxicity but none have been conducted in parallel with controlled clinical phototoxicity studies on systemically administered pharmaceuticals. The in vitro phototoxicity of eight fluoroquinolone (FQ) antibiotics (ciprofloxacin, grepafloxacin, lomefloxacin, norfloxacin, ofloxacin, trovafloxacin, BAYy3118, moxifloxacin) was determined by exposing Chinese hamster fibroblasts to UVA radiation. Cell damage was quantified with standard MTT or neutral red assays and an in vitro phototoxic index calculated (PI(vit)=% cell viability with UVA alone /% cell viability with UVA+FQ) for each endpoint. Clinical photosensitizing ability of the eight systemically administered FQ was investigated using double-blind, placebo and positive controlled, clinical skin phototesting of normal subjects. Minimal erythema doses at 365+/-30nm were determined before and after 6-7 days of FQ ingestion and PI(clin) (minimal erythema dose without FQ/minimal erythema dose with FQ) calculated. Linear regression analysis of PI(vit) vs PI(clin) gave correlations of up to 0.893. Principal components analysis of PI(vit), daily dose, plasma levels and photophysical (absorption) properties of the eight FQ showed that phototoxic (arbitrarily defined as PI(clin)> or =2) and non-phototoxic (PI(clin)<2) FQ could be completely discriminated using these parameters, and that the in vitro models were able to rank the relative phototoxic potential of the eight FQ.

Animals↗
PubMed2001

In vitro cytotoxicity of glyco-S-nitrosothiols. a novel class of nitric oxide donors.

The cytotoxicities of the nitric oxide (NO) donors, S-nitroso-N-acetylpencillamine (SNAP) and three glyco-SNAPs, glucose-1-SNAP, glucose-2-SNAP, and fructose-1-SNAP, towards the human gingival epithelioid S-G cell line and three human carcinoma cell lines derived from tissues of the oral cavity were compared using the neutral red (NR) assay. In general, the glucose-SNAPs were more cytotoxic than SNAP, which, in turn, was more cytotoxic than fructose-1-SNAP. Further studies focused on the response of S-G cells to glucose-2-SNAP. The cytotoxicity of glucose-2-SNAP was attributed to NO, as glucose-2-SNAP (t1/2=20 h at 28 degrees C) aged for 4 days was nontoxic, toxicity was eliminated in the presence of hydroxocobalamin, a specific NO scavenger, and toxicity was not noted with glucose-2-AP (the parent compound used to construct glucose-2-SNAP). Exposure of cells to glucose-2-SNAP resulted in a lessening of the intracellular level of glutathione and cells pretreated with the glutathione-depleter, 1,3-bis-(chloroethyl)-1-nitrosourea, were more sensitive to a subsequent challenge with glucose-2-SNAP. Cytotoxicity of glucose-2-SNAP was lessened upon coexposure with the antioxidants, myricetin, N-acetyl-L-cysteine, and L-ascorbic acid. S-G cells exposed to glucose-2-SNAP exhibited bi- and multinucleation. Death of S-G cells exposed to glucose-2-SNAP apparently occurred by apoptosis, as demonstrated with fluorescence microscopy by the appearance of brightly stained, hypercondensed chromatin in spherical cells and of membrane blebbing and by the DNA-ladder of oligonucleosome-length fragments noted with gel electrophoresis. In comparison with other classes of NO donors the sequence of toxicity towards S-G cells was S-nitrosoglutathione>glucose-SNAPs>SNAP, sodium nitroprusside>spermine NONOate>DPTA NONOate>DETA NONOate>fructose-1-SNAP>>SIN-1.

Antioxidants↗
PubMedDate not supplied

Haemopoietic cell proliferation in murine bone marrow cells exposed to extreme low frequency (ELF) electromagnetic fields.

As leukemia is one of the health hazards that is sometimes associated with exposure to extreme low frequency fields, we studied the in vitro effects of ELF fields on haemopoietic cell proliferation. First, the cytotoxic effect of 80 microT, 50 Hz magnetic fields on 3T3 cell proliferation was investigated using the neutral red test. Many chemicals are believed to cause damage because they interfere with basal or "housekeeping" cell functions. The basal cell functions are present in every cell. Non-specialized, actively dividing cells are suitable for measuring cytotoxic effects. Cytotoxic doses can be identified by exposing actively dividing cells in vitro and measuring growth inhibition caused by interference with these basal cell functions. 80 microT, 50 Hz magnetic fields caused no cytotoxicity: we were not able to demonstrate any interference with essential cell functions in the non-differentiated 3T3 cell line. Furthermore, the in vitro effects of ELF fields on murine haemopoietic and stromal stem cell proliferation were studied. Haemopoiesis is a continuous process, where mature blood cells are replaced by the proliferation and differentiation of more primitive progenitor and stem cells. Blood formation is tightly regulated by the stromal micro-environment. Exposure of murine bone marrow cells, from male and female mice, to 80 microT (50 Hz) magnetic fields showed a reduction in the proliferation and differentiation of the granulocyte-macrophage progenitor (CFU-GM) compared to non-exposed bone marrow cells. The results on the effect of the ELF-field on stromal stem cell proliferation (CFU-f) are somewhat equivocal at the moment. CFU-f from female mice showed a reduction while CFU-f from male mice were not decreased.

3T3 Cells↗