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At least 1,783 records · Page 99Linked to original sources
PubMed1998

Verapamil enhances the uptake and the photocytotoxic effect of PII, but not that of tetra(4-sulfonatophenyl)porphine.

The influence of the calcium channel blocker verapamil on the sensitivity of mouse fibrosarcoma cells of the line EMT-6 to treatment with Photofrin II (PII) or tetra(4-sulfonatophenyl)porphine (TPPS4) and light has been assessed. Cells were treated with 1.5 microg/ml PII or 75 microg/ml TPPS4 overnight in the absence or presence of 50 microg/ml verapamil and subsequently exposed to light. Verapamil increased the sensitivity of the EMT-6 cells to PII-induced photoinactivation by a factor of 2. In contrast, verapamil decreased the sensitivity of the cells to TPPS4-induced photoinactivation by 50-60%. Both sensitizers were found to be located to a large extent in lysosomes as revealed by fluorescence microscopy and by photochemical inactivation of the lysosomal marker enzyme beta-N-acetyl-D-glucosaminidase. Verapamil increased the uptake of PII by 30% and reduced the uptake of TPPS4 by 20%. Furthermore, verapamil enhanced the binding and uptake of LDL by about 40%. In conclusion, the effects of verapamil-induced sensitization of EMT-6 cells treated with PII or TPPS4 and light can to a large extent be attributed to the modulatory effects of verapamil on endocytosis.

Animals↗
PubMed1998

Growth inhibitory factor and zinc affect neural cell cultures in a tissue specific manner.

Deficiency of neuronal growth inhibitory factor (GIF) and abnormalities in zinc homeostasis have been suggested to play a role in the neuropathogenesis of Alzheimer's disease. We report here that embryonic chick cerebral cell cultures zinc and copper containing GIF in the presence of marmoset hippocampal extract reduces significantly and concentration dependently mitochondrial succinate dehydrogenase activity (MTT) and cell mass. In contrast, no indications could be found that GIF affected neural retina cell cultures. Our results suggest that the observed effects of GIF are not elicited by zinc.

Animals↗
PubMed2000

Formation of copper oxychloride and reactive oxygen species as causes of uterine injury during copper oxidation of Cu-IUD.

The lining of the uterus and cervix might be injured by a variety of oxidation products of Cu in a Cu-IUD, including cuprous ions, dissolved and precipitated cupric ions, and reactive oxygen species such as superoxide radicals, hydrogen peroxide, and hydroxyl radicals. In this study, the human amnious WISH cell line was employed as a model of uterine cells in the presence of copper. The cell viability was decreased by elemental copper, which was alleviated up to 70% by the addition of catalase. The addition of copper oxychloride caused cell death in a dose-dependent manner. Hydroxyl radicals in the presence of copper were determined by the formation of malondialdehyde. Soluble cuprous chloride complexes are formed in the uterus by slowly entering oxygen. The complexes are partly oxidized to insoluble copper oxychloride. which damages the endometrium. Unoxidized cuprous ions migrate to the oxygen-rich cervix and are oxidized to copper oxychloride, causing cervix damage.

Catalase↗
PubMed2003

Copper in the silk formation process of Bombyx mori silkworm.

Evidence is presented here that cupric ions play a part in the natural spinning of Bombyx mori silk. Proton induced X-ray emission studies revealed that the copper content increased from the posterior part to the anterior part of silk gland, and then further increased in the silk fiber. Spectrophotometric analysis demonstrated that cupric ions formed coordination complexes with silk fibroin chains while Raman spectroscopy indicated that they induced a conformation transition from random coil/helix to beta-sheet. Taken together these findings indicate that copper could play a role in the natural spinning process in silkworms.

Animals↗
PubMed1999

ATP-synthase of Rhodobacter capsulatus: coupling of proton flow through F0 to reactions in F1 under the ATP synthesis and slip conditions.

A stepwise increasing membrane potential was generated in chromatophores of the phototrophic bacterium Rhodobacter capsulatus by illumination with short flashes of light. Proton transfer through ATP-synthase (measured by electrochromic carotenoid bandshift and by pH-indicators) and ATP release (measured by luminescence of luciferin-luciferase) were monitored. The ratio between the amount of protons translocated by F0F1 and the ATP yield decreased with the flash number from an apparent value of 13 after the first flash to about 5 when averaged over three flashes. In the absence of ADP, protons slipped through F0F1. The proton transfer through F0F1 after the first flash contained two kinetic components, of about 6 ms and 20 ms both under the ATP synthesis conditions and under slip. The slower component of proton transfer was substantially suppressed in the absence of ADP. We attribute our observations to the mechanism of energy storage in the ATP-synthase needed to couple the transfer of four protons with the synthesis of one molecule of ATP. Most probably, the transfer of initial protons of each tetrad creates a strain in the enzyme that slows the translocation of the following protons.

Adenosine Diphosphate↗
PubMed1997

Effect of acute magnesium deficiency (MgD) on aortic endothelial cell (EC) oxidant production.

Magnesium deficiency (MgD) has been associated with production of reactive oxygen species, cytokines, and eicosanoids, as well as vascular compromise in vivo. Although MgD-induced inflammatory change occurs during "chronic" MgD in vivo, acute MgD may also affect the vasculature and consequently, predispose endothelial cells (EC) to perturbations associated with chronic MgD. As oxyradical production is a significant component of chronic MgD, we examined the effect of acute MgD on EC oxidant production in vitro. In addition we determined EC; pH, mitochondrial function, lysosomal integrity and general cellular antioxidant capacity. Decreasing Mg2+ (< or = 250microM) significantlyincreased EC oxidant production relative to control Mg2+ (1000microM). MgD-induced oxidant production, occurring within 30min, was attenuated by EC treatment with oxyradical scavengers and inhibitors of eicosanoid biosynthesis. Coincident with increased oxidant production were reductions in intracellular glutathione (GSH) and corresponding EC alkalinization. These data suggest that acute MgD is sufficient for induction of EC oxidant production, the extent of which may determine, at least in part, the extent of EC dysfunction/injury associated with chronic MgD.

Acute Disease↗
PubMed2000

Irniine, a pyrrolidine alkaloid, isolated from Arisarum vulgare can induce apoptosis and/or necrosis in rat hepatocyte cultures.

The effects of irniine, a pyrrolidine alkaloid extracted from the tubers of Arisarum vulgare, on rat hepatocyte primary cultures and rat liver epithelial cell line (RLEC) were studied. Cytotoxicity was first evaluated by LDH release, MTT and NR tests and MDA production, while cellular alterations were visualized by electron microscopy and DNA gel-electrophoresis. In hepatocyte and RLEC cultures, a major toxicity appeared at 40 microM of irniine and was demonstrated by an increase in LDH release and decreases in MTT reduction and NR uptake while concentrations lower than 40 microM did not induce significant changes in these parameters. However, we observed an increase in MDA production at 30 microM. Important alterations of the nuclei and mitochondria were also visualized by electron microscopy in cells treated with 50 microM. Using DNA gel-electrophoresis, we demonstrated that irniine at 40 and 50 microM induced DNA damage. All together these results demonstrate that: (1) Irniine induces a significant hepatotoxicity. (2) Irniine toxicity is not mediated by a metabolic derivative since RLEC, which do not contain a monooxygenase system, were also affected by this compound. (3) Irniine induces a significant DNA damage and oxidative stress which leads to cell death by necrosis and/or by apoptosis. Moreover, our data suggest that the alkaloid irniine contained in A. vulgare may be involved in the toxic symptoms observed after medicinal use or consumption of the plant tubers as food both by humans and animals.

Alkaloids↗
PubMed1995

Cytolethality of hemolytic Escherichia coli to primary human renal proximal tubular cell cultures obtained from different donors.

OBJECTIVES: In earlier experiments, we confirmed epidemiologic studies demonstrating the prominence in acute pyelonephritis of Escherichia coli expressing P fimbriae and hemolysin, produced the disease with pyelonephritogenic strains in an animal model, and developed in vitro assays using human renal proximal tubular cells that demonstrated bacterial adherence by P fimbriae and killing of the renal cells by hemolysin. In the present series of experiments, we sought to determine whether P-fimbriated hemolytic E coli killed human renal proximal tubular epithelial cells obtained from different human donors. METHODS: Human renal proximal tubular cells, putative target cells for bacteria causing acute pyelonephritis, were cultured from 9 donors and cell death was measured by two methods. RESULTS: We showed that the E coli strain was significantly more cytolethal for renal cells of all donors than its hemolysin-negative mutant. CONCLUSIONS: This work suggests that the pathogenesis of acute pyelonephritis by P-fimbriated hemolytic E coli, characteristics of the causative organism in about 50% of human cases, may be at least in part through killing of human renal epithelial cells by hemolysin.

Cell Survival↗
PubMed2002

Thrombomodulin expression in endothelial cells after contact with bone cement.

The expression of thrombomodulin after contact with CMW 1 bone cement extracts was studied in human umbilical vein endothelial cells. Cement extracts after 1 h and 7-day curing induced no significant variations in thrombomodulin antigen levels and in mRNA expression. Significant increase of thrombomodulin was observed when endothelial cells were treated with all-trans retinoic acid (ATRA). ATRA induced the increase of thrombomodulin also in cells incubated with cement extracts. These results suggest that CMW 1 bone cement does not impair the expression of thrombomodulin in endothelial cells.

Bone Cements↗
PubMed1996

Evidence that intersegmental competition influences the segmental distribution of the central terminals of muscle sensory afferents in the chicken embryo.

The possibility that muscle sensory afferents that enter the spinal cord at different segmental levels compete for terminal space in the lateral motor column was tested by unilaterally ablating neural crest cells destined to generate dorsal root ganglia (DRGs). Newly migrating neural crest was surgically removed from several lumbosacral segments on one side of the spinal cord on day 3 of embryogenesis (d3). The resultant experimental preparations developed without DRGs on the operated side at the segmental levels where the ablation was performed. At d18 the central projection from the intact DRG immediately caudal to the operated segments was anatomically mapped with a lipophilic axonal tracer. The central projection from the same DRG on the opposite, unoperated side was mapped as a control. The density of terminals along the longitudinal axis of the lateral motor column was quantified in serial sections with an image analysis program. On both the operated and control sides, the majority of terminals were found within the segment of entry and the rostral and caudal neighboring spinal segments. However, the rostral neighboring segment received a larger proportion of terminals on the operated side compared to the control side. Thus, the absence of primary afferents entering the spinal cord at specific segments leads to a shift of the afferent projection to the lateral motor column from the neighboring segments towards the deafferented segments.

Animals↗
PubMed2000

Indolocarbazoles exhibit strong antiviral activity against human cytomegalovirus and are potent inhibitors of the pUL97 protein kinase.

We have analyzed a panel of protein kinase inhibitors (PKIs) and found that some indolocarbazoles (Gö6976, K252a, K252c) proved to be highly effective inhibitors of GCV-sensitive and -resistant human cytomegalovirus (HCMV) strains, but did not show any effect against herpes simplex virus. Antiviral activity was determined by focus reduction assays (IC(50) ranging from 0.009 to 0.4 microM). Other inhibitors of serine/threonine kinases (Gö6850, H-7, roscovitine) were found to be ineffective. Virus yield at 5 days after infection was reduced by three orders of magnitude with nanomolar concentrations of the indolocarbazoles. These compounds were fully effective when added up to 24 h post infection and showed reduced activity up to 72 h post infection. Cytotoxicity assays in proliferating and non-proliferating cells demonstrated that the effective antiviral concentration of these compounds was significantly lower than either antiproliferative (IC(50)/CC(50) ranging from 6.5 to 390) or cytotoxic (IC(50)/CC(50) ranging from 72. 5 to 1000) doses. The effects of PKIs on the virus-encoded protein kinase pUL97 were studied using recombinant vaccinia viruses. Indolocarbazoles strongly inhibited both pUL97 autophosphorylation (IC(50) ranging from 0.0012 to 0.013 microM) and pUL97-dependent ganciclovir phosphorylation (IC(50) ranging from 0.05 to 0.26 microM). Other inhibitors of serine/threonine kinases showed only weak (Gö6850) or no (H-7, roscovitine) effect on these pUL97 functions, while oxoflavone tyrosine kinase inhibitors had no effect at all.

Antiviral Agents↗
PubMed2003

The antiviral activity of naturally occurring proteins and their peptide fragments after chemical modification.

Chemical modification of the proteins bovine serum albumin, alpha-lactalbumin, beta-lactoglobulin and chicken lysozyme by 3-hydroxyphthalic anhydride (3-HP) yielded compounds which exerted antiviral activity in vitro as compared with the native unmodified proteins. Of the three enveloped viruses tested, human herpes simplex virus type 1 (HSV-1), bovine parainfluenza virus type 3 and porcine respiratory corona virus, only HSV-1 proved sensitive to the 3-HP-proteins. All of the chemically modified proteins presented antiviral activity against HSV-1 when assayed before, during or after infection. However, to achieve HSV-1 inhibition, significantly higher concentrations of the modified proteins were required if present before infection as compared to during or after infection. Our results suggest that multiple mechanisms are involved in the inhibition of HSV-1 infection. Proteolytical digestion of albumin, alpha-lactalbumin, beta-lactoglobulin and lysozyme by trypsin, chymotrypsin and pepsin yielded several peptide fragments with antiherpetic activity. Chemical modification of these peptide fragments by 3-HP generated peptides with antiviral activity, however, this was almost always combined with a cytotoxic effect on the Vero cells. Overall, our results suggest that targeted chemical modification of some natural products might provide compounds effective against HSV-1 infection.

Albumins↗
PubMed1999

Dehydroepiandrosterone (DHEA) protects hippocampal cells from oxidative stress-induced damage.

It has been postulated that decreases in plasma levels of dehydroepiandrosterone (DHEA) may contribute to the development of some age-related disorders. Along with neuroprotective and memory enhancing effects, DHEA has been shown to display antioxidant properties. Moreover, oxidative stress is known to cause lipid peroxidation and degenerative changes in the hippocampus, an area involved in memory processes and especially afflicted in Alzheimer's disease (AD). Accordingly, we investigated the antioxidant effects of DHEA in models of oxidative stress using rat primary hippocampal cells and human hippocampal tissue from AD patients and age-matched controls. A pre-treatment of rat primary mixed hippocampal cell cultures with DHEA (10-100 microM) protected against the toxicity induced by H2O2 and sodium nitroprusside. Moreover, DHEA (10-100 microM) was also able to prevent H2O2/FeSO4-stimulated lipid oxidation in both control and AD hippocampal tissues. Taken together, these data suggest that DHEA may be useful in treating age-related central nervous system diseases based on its protective effects in the hippocampus.

Adjuvants, Immunologic↗
PubMed1999

Toxicity of selected plant volatiles in microbial and mammalian short-term assays.

In this study, several short-term microbial and mammalian in vitro assays were used to evaluate cytotoxicity and genotoxicity of four plant volatiles showing antifungal activity: cinnamaldehyde, carvacrol, thymol and S(+)-carvone. All inhibited viability and proliferation of Hep-2 cells in a dose-dependent manner. IC50 ranged from 0.3 mM (cinnamaldehyde) to 0.7 mM (thymol) in viability tests and from 0.2 mM (carvacrol) to 0.9 mM (carvone) in the proliferation test. The morphological analysis suggested an involvement of apoptosis in the cases of carvone, carvacrol and cinnamaldehyde. At nontoxic doses, carvacrol and thymol increased the number of revertants in the Ames test by 1.5-1.7 times, regardless of metabolic activation. In the SOS-chromotest, none of the four plant volatiles caused DNA damage at non-toxic doses. In the DNA repair test, a marked dose-dependent differential toxicity was observed with carvone and, to a lesser extent, with cinnamaldehyde, while with thymol and carvacrol, this effect was less pronounced. In conclusion, the considered in vitro cytotoxicity assays have shown to be sensitive enough to highlight a variety of toxic effects at the cellular level, which can be rather different between chemically closely related compounds, such as isomers.

Acrolein↗
PubMed2002

Cadmium induces alpha(1)collagen (I) and metallothionein II gene and alters the antioxidant system in rat hepatic stellate cells.

The mechanism of cadmium-mediated hepatotoxicity has been the subject of numerous investigations, principally in hepatocytes. Although, some uncertainties persist, sufficient evidence has emerged to provide a reasonable account of the toxic process in parenchymal cells. However, there is no information about the effect of cadmium in other hepatic cell types, such as stellate cells (fat storing cells, Ito cells, perisinusoidal cells, parasinusoidal cells, lipocytes). Hepatic stellate cells (HSC) express a quiescent phenotype in a healthy liver and acquire an activated phenotype in liver injury. These cells play an important role in the fibrogenic process. The objective of this study was to investigate the effect of a 24 h treatment of low Cd concentrations in glutathione content, lipid peroxidation damage, cytosolic free Ca, antioxidant enzyme activities: glutathione peroxidase, glutathione reductase, superoxide dismutase and catalase along with the capacity of this heavy metal to induce metallothionein II and alpha(1)collagen (I) in an hepatic stellate cell line (CFSC-2G). Cd-treated cells increased lipid peroxidation and the content of cytosolic free calcium, decreased glutathione content and superoxide dismutase, glutathione peroxidase and catalase activity. Cd was able to induce the expression of the metallothionein II and alpha(1)collagen (I) gene, that was not described in this cell type. Cadmium may act as a pro-fibrogenic agent in the liver probably by inducing oxidative damage by enhancing lipid peroxidation and altering the antioxidant system of the cells. Although, the exact role metallothionein induction plays in this process is unknown, it probably, provides a cytosolic pool of potential binding sites to sequester ionic Cd, thereby decreasing its toxicity.

Animals↗
PubMed1999

Long-term effects of a single dose of brain-derived neurotrophic factor on motoneuron survival following spinal root avulsion in the adult rat.

The long-term effect of a single dose of Brain-derived neurotrophic factor (BDNF) treatment on adult motoneuron survival and on expression of nitric oxide synthase (NOS) following nerve injury (avulsion) was investigated and compared with that of continuous BDNF treatment. By 6 weeks post-injury, more than 80% of motoneurons survived in animals treated with either a single dose or continuous treatment of BDNF, while only 30% of motoneurons survived in control animals (avulsion only). There were no significant differences in motoneuron survival between animals receiving a single dose and those with continuous treatment of BDNF. Additionally, the expression of NOS in avulsed motoneurons was almost completely inhibited in all BDNF treatment groups regardless of the mode of administration (single vs. continuous). These data indicate that treatment with a single dose of BDNF at the time of injury can inhibit NOS expression and provide the first evidence that in this situation BDNF has a long-term rescue effect on adult motoneuron survival after root avulsion.

Age Factors↗