Long-term effects of chromium, grape seed extract, and zinc on various metabolic parameters of rats

Progressive insulin resistance may contribute to both enhanced glycosylation of proteins and nucleic acids and augmented free radical damage commonly associated with aging. Accordingly, ingestion of chromium and antioxidants which improve insulin sensitivity and/or lessen free radical formation could theoretically ameliorate these basic disorders and lessen signs and symptoms of chronic age-related disorders. However, this supposition is based primarily upon acute rather than chronic data. Therefore, we divided 104 F344/BN rats into 2 groups: a control group receiving a basic diet and a test group receiving the same diet with added chromium polynicotinate (5 ppm), zinc monomethionine (18 ppm elemental zinc), and a grape seed extract high in flavonoids (250 ppm). Initial mean systolic blood pressures (SBP) of both control and test groups were 122 mm Hg. Over the first 7 months, the SBP of the control animals steadily increased to 140 mm Hg and remained at this level for the next 7-8 months. In contrast, the SBP of the test animals initially decreased over the first 4 months to as low as 110-114 mm Hg. The SBP then increased over the following months, essentially reaching the starting value of 120 mm Hg. This was still significantly lower than control (p < 0.001). In 12 control and 12 test rats, hepatic TBARS formation, an estimate of lipid peroxidation/free radical formation, was significantly lower after 1 year ingesting the test diet (p < 0.04); and HbA1C was also statistically significantly lower in the test group (5.4 vs. 4.8%, p < 0.003). Circulating levels of cholesterol, HDL, and triglycerides were similar between the two groups. Body, kidney, and liver weights were not different after 1 year ingesting the different diets; but epididymal fat pad weight was less in the group receiving supplements. We conclude that after prolonged supplementation a combination of agents known to sensitize insulin response and act as antioxidants (chromium polynicotinate, grape seed extract, and zinc monomethionine) can markedly lower SBP in normotensive rats, lessen oxidative damage to fats as suggested by decreased TBARS formation, and lower HbA1C without showing signs of toxicity.

Oxidative mechanisms in the toxicity of chromium and cadmium ions

Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.

The cellular and molecular basis of health benefits of grape seed proanthocyanidin extract

Red grape seed extract containing proanthocyanidins and other antioxidants are being used as nutritional supplements by many health conscious individuals. The beneficial effects of grape seed proanthocyanidins (GSPE) have been reported, however, little is known about their mechanism(s) of action. One of the beneficial effects of GSPE is chemoprevention of cellular damage. The precise mechanism by which GSPE mediates, chemoprevention is not yet understood. This report addresses this issue. We investigated the mechanisms of actions of GSPE, which ameliorates chemotherapy-induced toxic effects of Idarubicin (Ida) and 4,-hydroxyperoxycyclophosphamide (4-HC) in normal human Chang liver cells. Exposure to GSPE resulted in a significant reduction in apoptosis in response to the cytotoxicity of chemotherapeutic agents. RT-PCR analysis showed a significant increase in the anti-apoptotic gene Bcl-2 and a decrease in the cell cycle associated and proapoptotic genes, c-myc and p53 in cells treated with GSPE. These results suggest that some of the chemopreventive effects of GSPE are mediated by upregulating Bcl-2 and down regulating c-myc and p53 genes.

Chromium (VI)-induced oxidative stress, apoptotic cell death and modulation of p53 tumor suppressor gene

Chromium (VI) is a widely used industrial chemical, extensively used in paints, metal finishes, steel including stainless steel manufacturing, alloy cast irons, chrome, and wood treatment. On the contrary, chromium (III) salts such as chromium polynicotinate, chromium chloride and chromium picolinate, are used as micronutrients and nutritional supplements, and have been demonstrated to exhibit a significant number of health benefits in rodents and humans. However, the cause for the hexavalent chromium to induce cytotoxicity is not entirely understood. A series of in vitro and in vivo studies have demonstrated that chromium (VI) induces an oxidative stress through enhanced production of reactive oxygen species (ROS) leading to genomic DNA damage and oxidative deterioration of lipids and proteins. A cascade of cellular events occur following chromium (VI)-induced oxidative stress including enhanced production of superoxide anion and hydroxyl radicals, increased lipid peroxidation and genomic DNA fragmentation, modulation of intracellular oxidized states, activation of protein kinase C, apoptotic cell death and altered gene expression. In this paper, we have demonstrated concentration- and time-dependent effects of sodium dichromate (chromium (VI) or Cr (VI)) on enhanced production of superoxide anion and hydroxyl radicals, changes in intracellular oxidized states as determined by laser scanning confocal microscopy, DNA fragmentation and apoptotic cell death (by flow cytometry) in human peripheral blood mononuclear cells. These results were compared with the concentration-dependent effects of chromium (VI) on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Chromium (VI)-induced enhanced production of ROS, as well as oxidative tissue and DNA damage were observed in these cells. More pronounced effect was observed on chronic myelogenous leukemic K562 cells and J774A.1 murine macrophage cells. Furthermore, we have assessed the effect of a single oral LD50 dose of chromium (VI) on female C57BL/6Ntac and p53-deficient C57BL/6TSG p53 mice on enhanced production of superoxide anion, lipid peroxidation and DNA fragmentation in the hepatic and brain tissues. Chromium (VI)-induced more pronounced oxidative damage in p53 deficient mice. This in vivo study highlighted that apoptotic regulatory protein p53 may play a major role in chromium (VI)-induced oxidative stress and toxicity. Taken together, oxidative stress and oxidative tissue damage, and a cascade of cellular events including modulation of apoptotic regulatory gene p53 are involved in chromium (VI)-induced toxicity and carcinogenesis.

Protective effect of melatonin on naphthalene-induced oxidative stress and DNA damage in cultured macrophage J774A.1 cells

Naphthalene is a bicyclic aromatic compound that is widely used in various domestic and commercial applications. Previous studies in our laboratory have demonstrated enhanced production of reactive oxygen species, lipid peroxidation and DNA fragmentation in both in vitro and in vivo models following treatment with naphthalene. Melatonin (N-acetyl-5-methoxytryptamine), an indole hormone, is the chief secretory product of the pineal gland and is an efficient free radical scavenger and antioxidant, both in vitro and in vivo. In this study, we have investigated the ability of 1 mM melatonin to protect against naphthalene-induced oxidative stress and DNA damage in cultured macrophage J774A.1 cells. No significant changes were observed when these macrophage cells were treated with 100 microM naphthalene. Approximately 2.0-, 4.2- and 4.4-fold increases in cytochrome c reduction were observed at 200, 400 and 500 mM concentrations of naphthalene, demonstrating the increased production of superoxide anion. At 24 h, lipid peroxidation increased by approximately 1.4-, 2.1- and 2.2-fold following treatment of these cells with 200, 400 and 500 mM concentrations of naphthalene, respectively, while 1.6-, 2.8- and 2.8-fold increases in DNA fragmentation were observed at these same concentrations. Two hour pretreatment of these cultured cells with 1 mM melatonin provided approximately 26-44% decreases in lipid peroxidation, superoxide anion production and DNA fragmentation in cells treated with 400 and 500 microM naphthalene. Cellular viability decreased significantly when cells were incubated with concentrations of naphthalene greater than 100 microM, while preincubation with melatonin significantly increased the cellular viability. These results demonstrate that naphthalene may induce toxic manifestations by enhanced production of reactive oxygen free radicals, resulting in lipid peroxidation and DNA damage, while preincubation with melatonin significantly suppressed cytoxicity in J774A.1 macrophage cells.

Protection of primary glial cells by grape seed proanthocyanidin extract against nitrosative/oxidative stress

Previous studies showed that proanthocyanidins provide potent protection against oxidative stress. Here we investigate the effects of grape seed proanthocyanidin extract (GSPE) as a novel natural antioxidant on the generation and fate of nitric oxide (NO) in rat primary glial cell cultures. GSPE treatment (50 mg/L) increased NO production (measured by NO(2-) assay) by stimulation of the inducible isoform of NOS. However, GSPE failed to affect the LPS/IFN-gamma-induced NO production or iNOS expression. Similar responses were found in the murine macrophage cell line RAW264.7. GSPE did not show any effect on dihydrodichlorofluorescein fluorescence (ROS marker with high sensitivity toward peroxynitrite) either in control or in LPS/IFN-gamma-induced glial cultures even in the presence of a superoxide generator (PMA). GSPE treatment alone had no effect on the basal glutathione (GSH) status in glial cultures. Whereas the microglial GSH level declined sharply after LPS/IFN-gamma treatment, the endogenous GSH pool was protected when such cultures were treated additionally with GSPE, although NO levels did not change. Glial cultures pretreated with GSPE showed higher tolerance toward application of hydrogen peroxide (H(2)O(2)) and tert-butylhydroperoxide. Furthermore, GSPE-pretreated glial cultures showed improved viability after H(2)O(2)-induced oxidative stress demonstrated by reduction in lactate dehydrogenase release or propidium iodide staining. We showed that, in addition to its antioxidative property, GSPE enhances low-level production of intracellular NO in primary rat astroglial cultures. Furthermore, GSPE pretreatment protects the microglial GSH pool during high output NO production and results in an elevation of the H(2)O(2) tolerance in astroglial cells.

Acute and long-term safety evaluation of a novel IH636 grape seed proanthocyanidin extract

Grape seed proanthocyanidins are known to possess a broad spectrum of pharmacological, medicinal and therapeutic properties. Previous studies in our laboratories have demonstrated the various protective abilities of a novel IH636 grape seed proanthocyanidin extract (GSPE) against various pathologic conditions. However no extensive safety studies have been conducted on grape seed proanthocyanidins to date. This study demonstrates the acute and chronic safety studies on GSPE. Acute oral toxicity, dermal toxicity, dermal irritation and eye irritation studies have been conducted. The LD50 of GSPE was found to be greater than 5000 mg/kg when administered once orally via gastric intubation to fasted male and female albino rats. The LD50 of GSPE was found to be greater than 2000 mg/kg when administered once for 24 hr to the clipped, intact skin of male and female albino rats. In addition, 2000 mg/kg was found to be the no-observed-effect level (NOEL) for systemic toxicity under the conditions of the study. In a dermal irritation study, GSPE received a descriptive rating classification of moderately irritating. Extensive chronic studies were also conducted. We have assessed the effects of chronic administration of 100 mg GSPE/kg/day for twelve months and its effect on seven vital target organs, namely, brain, heart, intestine, kidney, liver, lung and spleen, and on serum chemistry changes in male B6C3F1 mice. Furthermore, the dose-dependent chronic effects of GSPE in female B6C3F1 mice were evaluated. Mice were fed 0, 100, 250 or 500 mg GSPE/kg/day for six months and the effects of GSPE exposure were examined on brain, duodenum, heart, kidney, liver, lung, pancreas and spleen, and on serum chemistry changes in female mice. These acute studies demonstrated that GSPE is safe and did not cause any detrimental effects in vivo under the conditions investigated in this study.

Effect of hydroxycitric acid on serotonin release from isolated rat brain cortex

There is evidence that hydroxycitric acid (HCA), an extract of dried fruit rind of South Asian trees of the genus Garcinia cambogia, can reduce food intake in experimental animals. In the present study, we investigated the effect of HCA on basal and potassium-depolarization evoked increase in radiolabeled serotonin ([3H]-5-HT) release from rat brain cortex slices in vitro. HCA (10 microM-1 mM) altered the baseline of spontaneous tritium efflux but had no significant effect on potassium-evoked release of [3H]-5-HT. When applied on its own, HCA (10 microM-1 mM) elicited a concentration-dependent increase in efflux of [3H]-5-HT reaching a maximum at 300 microM. We conclude that HCA can increase the release of radiolabeled 5-HT from the isolated rat brain cortex.

Differential effects of IH636 grape seed proanthocyanidin extract and a DNA repair modulator 4-aminobenzamide on liver microsomal cytochrome 4502E1-dependent aniline hydroxylation

Previous studies from our laboratories have linked the protective abilities of IH636 grape seed proanthocyanidin extract (GSPE) with inactivation of anti-apoptotic gene bcl-XL, and modification of several other critical molecular targets such as DNA-damage/DNA-repair, lipid peroxidation and intracellular Ca2+ homeostasis. Especially, GSPE provided dramatic protection against acetaminophen (APAP)-induced hepatotoxicity, significantly increased bcl-XL expression in the liver, and antagonized both necrotic and apoptotic deaths of liver cells in vivo. However, it was not clear from this study whether anti-apoptogenic and anti-necrotic effects of GSPE were: (i) due to its interference with endonuclease activity, (ii) due to its antioxidant effect, or, (iii) due to its ability to inhibit microsomal drug metabolizing enzyme(s), such as CYP-4502E1. Since CYP-4502E1 primarily metabolizes acetaminophen in mice and rats, this study specifically focused on CYP-4502E1's catalytic activity in vitro. Overall this investigation compared the in vitro aniline hydroxylation patterns of: (i) in vivo GSPE-exposed and unexposed (control) mouse liver microsomes, (ii) induced (1% acetone in drinking water for 3 days) and uninduced rat liver microsomes in the presence and absence of GSPE in vitro, and (iii) control rat liver microsomes in the presence of an anti-APAP agent 4-aminobenzamide (4-AB) in vitro. For the in vivo assessment, male B6C3F1 mice were fed GSPE diet (ADI 100 mg/kg body wt) for 4 weeks, and liver microsomes were isolated from both control and GSPE-fed mice for aniline hydroxylation, a specific marker of CYP-4502E1 activity. Data show that hydroxylation was 40% less in microsomes from GSPE-exposed livers compared to control microsomes. Similarly, when rat liver microsomes were incubated with various concentrations of GSPE in vitro (100 and 250 microg/ml), aniline hydroxylation was inhibited to various degrees (uninduced: 40 and 60% and induced: 25 and 50%, respectively with 100 and 250 microg/ml). Influence of GSPE on hydroxylation patterns were compared with another hepatoprotective agent 4-aminobenzamide (4-AB), a well-known modulator of nuclear enzyme poly(ADP-ribose) polymerase, and the data shows that 4-AB did not alter aniline hydroxylation at all. Collectively, these results may suggest that GSPE has the ability to inhibit CYP-4502E1, and this is an additional cytoprotective attribute, in conjunction with its novel antioxidant and/or antiendonucleolytic potential.

Regulation of inducible adhesion molecule expression in human endothelial cells by grape seed proanthocyanidin extract

Altered expression of cell adhesion molecule expression has been implicated in a variety of chronic inflammatory conditions. Regulation of adhesion molecule expression by specific redox sensitive mechanisms has been reported. Grape seed proanthocyanidins have been reported to have potent antioxidant properties. We evaluated the effects of grape seed proanthocyanidin extract (GSPE) on the expression of TNFalpha-induced ICAM-1 and VCAM-1 expression in primary human umbilical vein endothelial cells (HUVEC). GSPE at low concentrations (1-5 micrograms/ml), down-regulated TNFalpha-induced VCAM-1 expression but not ICAM-1 expression in HUVEC. Such regulation of inducible VCAM-1 by GSPE was also observed at the mRNA expression level. A cell-cell co-culture assay was performed to verify whether the inhibitory effect of GSPE on the expression of VCAM-1 was also effective in down-regulating actual endothelial cell/leukocyte interaction. GSPE treatment significantly decreased TNFalpha-induced adherence of T-cells to HUVEC. Although several studies have postulated NF-kappaB as the molecular site where redox active substances act to regulate agonist-induced ICAM-1 and VCAM-1 gene expression, inhibition of inducible VCAM-1 gene expression by GSPE was not through a NF-kappaB-dependent pathway as detected by a NF-kappaB reporter assay. The potent inhibitory effect of low concentrations of GSPE on agonist-induced VCAM-1 expression suggests therapeutic potential of this extract in inflammatory conditions and other pathologies involving altered expression of VCAM- 1.

Chemopreventive effects of grape seed proanthocyanidin extract on Chang liver cells

In an attempt to ameliorate the chemotherapy associated normal cell toxicity, in this study a known antioxidant, grape seed proanthocyanidin extract (GSPE) using Chang liver cells has been used. Chang liver cells were treated in vitro with idarubicin (Ida) (30 nM) and 4-hydroxyperoxycyclophosphamide (4-HC) (1 microg/ml) with or without proanthocyanidin (25 microg/ml). The cells were grown in vitro and the growth rate of the cells were determined using MTT assay. The results showed that the GSPE decreased growth inhibitory effects of Ida and 4-HC on Chang liver cells in vitro. Since these chemotherapeutic agents are known to induce apoptosis in the target cells, these cells were also analyzed for presence of apoptotic cells using flow cytometry. The GSPE decreased the number of apoptotic cell population induced by either chemotherapy. In an attempt to determine the mechanisms of ameliorating effects of proanthocyanidin, the expression of apoptosis/cell cycle/growth related genes, Bcl-2, p53 and c-myc was determined in the treated and control cells using Western blotting or reverse transcriptase-polymerase chain reaction (RT-PCR) techniques. There was an increased expression of Bcl-2 in the cells treated with GSPE. However, there was a significant decrease in the expression of other cell cycle related genes such as p53 and c-myc in these cells following treatment with GSPE. Thus, these results indicate that proanthocyanidin can be a potential candidate to ameliorate the toxic effects associated with chemotherapeutic agents used in treatment of cancer.

Oxidative mechanisms in the toxicity of chromium and cadmium ions

Chromium and cadmium are widely used industrial chemicals. The toxicities associated with both metal ions are well known. However, less information is available concerning the mechanisms of toxicity. The results of in vitro and in vivo studies demonstrate that both cations induce an oxidative stress that results in oxidative deterioration of biological macromolecules. However, different mechanisms are involved in the production of the oxidative stress by chromium and cadmium. Chromium undergoes redox cycling, while cadmium depletes glutathione and protein-bound sulfhydryl groups, resulting in enhanced production of reactive oxygen species such as superoxide ion, hydroxyl radicals, and hydrogen peroxide. These reactive oxygen species result in increased lipid peroxidation, enhanced excretion of urinary lipid metabolites, modulation of intracellular oxidized states, DNA damage, membrane damage, altered gene expression, and apoptosis. Enhanced production of nuclear factor-kappaB and activation of protein kinase C occur. Furthermore, the p53 tumor suppressor gene is involved in the cascade of events associated with the toxicities of these cations. In summary, the results clearly indicate that although different mechanisms lead to the production of reactive oxygen species by chromium and cadmium, similar subsequent mechanisms and types of oxidative tissue damage are involved in the overall toxicities.

Cadmium- and chromium-induced oxidative stress, DNA damage, and apoptotic cell death in cultured human chronic myelogenous leukemic K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells

Sodium dichromate [Cr(VI)] and cadmium chloride [Cd(II)] are both cytotoxic and mutagenic. This study examined the toxic and apoptotic potentials of these two cations on three cell types in vitro, namely, human chronic myelogenous leukemic (CML) K562 cells, promyelocytic leukemic HL-60 cells, and normal human peripheral blood mononuclear cells. The cells were incubated with 0-100 microM concentrations of the two cations for 0, 24, or 48 hours at 37 degrees C. Both Cr(VI) and Cd(II) induced changes in intracellular oxidized states of cells, which were detected using laser scanning confocal microscopy. Cell cycle modulation and apoptosis of the K562 cells by Cr(VI) and Cd(II) were determined by flow cytometry. Significant decreases in the G2/M phase were observed in the Cr(VI) and Cd(II) treated CML cells compared with untreated cells. At 12.5 microM, Cr(VI) induced greater apoptosis in K562 cells as compared with Cd(II). In the K562 cells, 2.2- and 3.0-fold increases in DNA fragmentation were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.2- and 1.7-fold increases in DNA fragmentation were observed with Cd(II). Furthermore, approximately 2.7- and 4.9-fold increases in cytochrome c reduction were observed following incubation with 12.5 and 25 microM Cr(VI), respectively, and 1.6- and 3.3-fold increases in cytochrome c reduction were observed with Cd(II), demonstrating enhanced production of superoxide anion. Approximately 3.1 to 6-fold increases in hydroxyl radical production were observed following incubation of the K562 cells with these cations at 12.5 and 25 microM concentrations. These results in K562 cells were compared with promyelocytic leukemic HL-60 cells and normal human peripheral blood mononuclear cells. More pronounced effects were observed on K562 and HL-60 cells, and much lesser effects were observed on normal human peripheral blood mononuclear cells. The results demonstrate that both cations are toxic, producing oxidative tissue damage and apoptosis. Furthermore, more drastic effects were observed on K562 and HL-60 cells as compared with normal human peripheral blood mononuclear cells.

Free radicals and grape seed proanthocyanidin extract: importance in human health and disease prevention

Free radicals have been implicated in over a hundred disease conditions in humans, including arthritis, hemorrhagic shock, atherosclerosis, advancing age, ischemia and reperfusion injury of many organs, Alzheimer and Parkinson's disease, gastrointestinal dysfunctions, tumor promotion and carcinogenesis, and AIDS. Antioxidants are potent scavengers of free radicals and serve as inhibitors of neoplastic processes. A large number of synthetic and natural antioxidants have been demonstrated to induce beneficial effects on human health and disease prevention. However, the structure-activity relationship, bioavailability and therapeutic efficacy of the antioxidants differ extensively. Oligomeric proanthocyanidins, naturally occurring antioxidants widely available in fruits, vegetables, nuts, seeds, flowers and bark, have been reported to possess a broad spectrum of biological, pharmacological and therapeutic activities against free radicals and oxidative stress. We have assessed the concentration- or dose-dependent free radical scavenging ability of a novel IH636 grape seed proanthocyanidin extract (GSPE) both in vitro and in vivo models, and compared the free radical scavenging ability of GSPE with vitamins C, E and beta-carotene. These experiments demonstrated that GSPE is highly bioavailable and provides significantly greater protection against free radicals and free radical-induced lipid peroxidation and DNA damage than vitamins C, E and beta-carotene. GSPE was also shown to demonstrate cytotoxicity towards human breast, lung and gastric adenocarcinoma cells, while enhancing the growth and viability of normal human gastric mucosal cells. The comparative protective effects of GSPE, vitamins C and E were examined on tobacco-induced oxidative stress and apoptotic cell death in human oral keratinocytes. Oxidative tissue damage was determined by lipid peroxidation and DNA fragmentation, while apoptotic cell death was assessed by flow cytometry. GSPE provided significantly better protection as compared to vitamins C and E, singly and in combination. GSPE also demonstrated excellent protection against acetaminophen overdose-induced liver and kidney damage by regulating bcl-X(L) gene, DNA damage and presumably by reducing oxidative stress. GSPE demonstrated excellent protection against myocardial ischemia-reperfusion injury and myocardial infarction in rats. GSPE was also shown to upregulate bcl(2) gene and downregulate the oncogene c-myc. Topical application of GSPE enhances sun protection factor in human volunteers, as well as supplementation of GSPE ameliorates chronic pancreatitis in humans. These results demonstrate that GSPE provides excellent protection against oxidative stress and free radical-mediated tissue injury.

Dietary coenzyme Q(10) supplement renders swine hearts resistant to ischemia-reperfusion injury

To examine whether nutritional supplementation of coenzyme Q(10) (CoQ(10)) can reduce myocardial ischemia-reperfusion injury, a group of swine was fed a regular diet supplemented with CoQ(10) (5 mg x kg(-1) x day(-1)) for 30 days. Another group of pigs that were fed a regular diet supplemented with placebo served as a control. After 30 days, isolated in situ pig hearts were prepared and hearts were perfused with a cardiopulmonary pump system. Each heart was subjected to 15 min of regional ischemia by snaring of the left anterior descending coronary artery, followed by 60 min of hypothermic cardioplegic global ischemia and 120 min of reperfusion. After the experiments were completed, myocardial infarct size was measured by triphenyltrazolium chloride staining methods. Postischemic left ventricular contractile function was better recovered in the CoQ(10) group than in the control group of pigs. CoQ(10)-fed pigs revealed less myocardial infarction and less creatine kinase release from the coronary effluent compared with control pigs. The experimental group also demonstrated a smaller amount of malonaldehyde in the coronary effluent and a higher content of the endogenous antioxidants ascorbate and thiol. Significant induction of the expression of ubiquitin mRNA was also found in the hearts of the CoQ(10)-fed group. The results of this study demonstrate that nutritional supplementation of CoQ(10) renders the hearts resistant to ischemia-reperfusion injury, probably by reducing the oxidative stress.

Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (VI) in liver and brain tissues of mice

It has been postulated that tumor suppressor genes are involved in the cascade of events leading to the toxicity of diverse xenobiotics. Therefore, we have assessed the comparative effects of 0.01, 0.10, and 0.50 median lethal doses (LD(50)) of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene, and sodium dichromate (VI) [Cr(VI)] on lipid peroxidation, DNA fragmentation, and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of p53-deficient and standard C57BL/6NTac mice to determine the role of p53 gene in the toxic manifestations produced by these diverse xenobiotics. In general, p53-deficient mice are more susceptible to all four xenobiotics than C57BL/6NTac mice, with dose-dependent effects being observed. Specifically, at a 0.50 LD(50) dose, naphthalene and Cr(VI) induced the greatest toxicity in the liver tissue of mice, and naphthalene and endrin exhibited the greatest effect in the brain tissue. At this dose, TCDD, endrin, naphthalene, and Cr(VI) induced 2.3- to 3.7-fold higher increases in hepatic lipid peroxidation and 1.8- to 3.0-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. At a 0. 10 LD(50) dose, TCDD, endrin, naphthalene, and Cr(VI) induced 1.3- to 1.8-fold higher increases in hepatic lipid peroxidation and 1.4- to 1.9-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. Similar results were observed with respect to DNA fragmentation and cytochrome c reduction (superoxide anion production). For example, at the 0.10 LD(50) dose, the four xenobiotics induced increases of 1.6- to 3. 0-fold and 1.5- to 2.1-fold in brain and liver DNA fragmentation, respectively, and increases of 1.5- to 2.3-fold and 1.4- to 2.5-fold in brain and liver cytochrome c reduction (superoxide anion production), respectively, in p53-deficient mice compared with control C57BL/6NTac mice. These results suggest that the p53 tumor suppressor gene may play a role in the toxicity of structurally diverse xenobiotics.

Myocardial protection by protykin, a novel extract of trans-resveratrol and emodin

Protykin is an all-natural, high potency standardized extract of trans-resveratrol (20%) and emodin (10%) derived from the dried rhizome of Polygonum cuspidatum. Previous studies have demonstrated free radical scavenging and anti-inflammatory activities of resveratrol. Since free radicals play a crucial role in the pathogenesis of myocardial ischemia/reperfusion injury, we examined whether Protykin could preserve the heart during ischemic arrest. Sprague-Dawley rats were divided into two groups: experimental group was gavaged Protykin (100 mg/kg body wt) dissolved in corn oil for three weeks, while the control group was gavaged corn oil alone. After three weeks, rats were sacrificed, isolated hearts perfused via working mode, were made globally ischemic for 30 min followed by 2 h of reperfusion. Left ventricular functions were continuously monitored and malonaldehyde (MDA) (presumptive marker for oxidative stress) formation were estimated. At the end of each experiment, myocardial infarct size was measured by TTC staining method. Peroxyl radical scavenging activity of Protykin was determined by examining its ability to remove peroxyl radical generated by 2,2'-azobis (2-amidinopropane) dihydrochloride, while hydroxy radical scavenging activity was tested with its ability to reduce 7-OH*-coumarin-3-carboxylic acid. The results of our study demonstrated that the Protykin group provided cardioprotection as evidenced by improved post-ischemic left ventricular functions (dp, dp/dt(max)) and aortic flow as compared to control group. This was further supported by the reduced infarct size in the Protykin group. Formation of MDA was also reduced by Protykin treatment. In vitro studies demonstrated that Protykin possessed potent peroxyl and hydroxyl radical scavenging activities. The results of this study indicate that Protykin can provide cardioprotection, presumably by virtue of its potent free radical scavenging activity.

Mechanism of gastroprotection by bismuth subsalicylate against chemically induced oxidative stress in cultured human gastric mucosal cells

Reactive oxygen species (ROS) are implicated in the pathogenesis of chemically induced gastric mucosal injury. We have investigated the effects of ethanol, hydrochloric acid (HCl), and sodium hydroxide (NaOH) on: (1) enhanced production of ROS including superoxide anion and hydroxyl radicals, (2) modulation of intracellular oxidized states by laser scanning confocal microscopy, and (3) DNA fragmentation, indices of oxidative tissue, and DNA damage in a primary culture of normal human gastric mucosal cells (GC), which were isolated and cultured from Helicobacter pylori-negative endoscopic biopsies from human subjects. The induction of ROS and DNA damage in these cells following exposure to ethanol (15%), HCl (150 mM) and NaOH (150 mM) were assessed by cytochrome c reduction (superoxide anion production), HPLC detection for enhanced production of hydroxyl radicals, changes in intracellular oxidized states by laser scanning confocal microscopy, and DNA damage by quantitating DNA fragmentation. Furthermore, the protective ability of bismuth subsalicylate (BSS) was assessed at concentrations of 25, 50, and 100 mg/liter. Incubation of GC with ethanol, HCI, and NaOH increased superoxide anion production by approximately 8.0-, 6.1-and 7.1-fold and increased hydroxyl radical production by 13.3-, 9.6-, and 8.9-fold, respectively, compared to the untreated gastric cells. Incubation of GC with ethanol, HCl, and NaOH increased DNA fragmentation by approximately 6.7-, 4.3-, and 4.8-fold, respectively. Approximately 20.3-, 17.5-, and 13.1-fold increases in fluorescence intensities were observed following incubation of gastric cells with ethanol, HCl, and NaOH, respectively, demonstrating dramatic changes in the intracellular oxidized states of GC following exposure to these necrotizing agents. Preincubation of GC with 25, 50, and 100 mg/liter of BSS decreased ethanol-induced increases in intracellular oxidized states in these cells by 36%, 56%, and 66%, respectively, demonstrating a concentration-dependent protective ability by BSS. Similar results were observed with respect to BSS in terms of superoxide anion and hydroxyl radical production, and DNA damage. The present study demonstrates that ethanol, HCl, and NaOH induce oxidative stress and DNA damage in GC and that BSS can significantly attenuate gastric injury by scavenging these ROS.

The cytotoxic effects of a novel IH636 grape seed proanthocyanidin extract on cultured human cancer cells

Grape seed proanthocyanidins are natural antioxidants which possess a broad spectrum of chemoprotective properties against free radicals and oxidative stress. In this study, we have assessed the cytotoxicity of a novel IH636 grape seed proanthocyanidin extract (GSPE) against MCF-7 human breast cancer cells, A-427 human lung cancer cells, CRL-1739 human gastric adenocarcinoma cells and K562 chronic myelogenous leukemic cells at 25 and 50 mg/lit concentrations for 0-72 h using cytomorphology and MTT cytotoxicity assay. In addition, we compared the effects on normal human gastric mucosal cells and normal J774A.1 murine macrophage cells with the effects on the cancer cell lines. Concentration- and time-dependent cytotoxic effects of GSPE were observed on the MCF-7 breast cancer, A-427 lung cancer and gastric adenocarcinoma cells. Following incubation of the MCF-7 cells with 25 mg/lit of the GSPE approximately 6.5, 30 and 43% inhibitions in cell growth were observed at 24, 48 and 72 h of incubation, respectively, while incubation of the MCF-7 cells with 50 mg/lit of the GSPE resulted in 11, 35 and 47% inhibition in cell growth at these same points, respectively. Similar results were observed in the A-427 and gastric adenocarcinoma cells. GSPE exhibited no cytotoxicity toward the neoplastic K562 myelogenous leukemic cells. However, GSPE enhanced the growth and viability of the normal human gastric mucosal cells and J774A.1 murine macrophage cells. These data demonstrate that GSPE exhibited cytotoxicity towards some cancer cells, while enhancing the growth and viability of the normal cells which were examined.

A novel proanthocyanidin IH636 grape seed extract increases in vivo Bcl-XL expression and prevents acetaminophen-induced programmed and unprogrammed cell death in mouse liver

Several molecular events in the apoptotic or necrotic death of hepatocytes induced by acetaminophen (AAP) now appear to be well defined. Recent studies also indicate that select expression of bcl-Xl is possibly modified during AAP-induced liver injury. The purpose of this study was several-fold: (i) to examine the hepatoprotective ability of short-term (3-day) and long-term (7-day) exposures of a grape seed proanthocyanidin extract (GSPE) on AAP-induced liver injury and animal lethality; (ii) to monitor effects of GSPE on one of the prime targets of AAP, i.e., hepatocellular genomic DNA and associated apoptotic and necrotic death; and (iii) to unravel changes in the pattern of expression of an antiapoptotic gene, bcl-Xl in the liver. In order to investigate these events, male ICR mice (30-40 g) were administered nontoxic doses of GSPE (3 or 7 days, 100 mg/kg, po), followed by hepatotoxic doses of AAP (400 and 500 mg/kg, ip), and sacrificed 24 h later. Serum was analyzed for alanine aminotransferase activity (ALT) and the liver for histopathological diagnosis of apoptosis/necrosis. The ability of AAP to promote apoptotic DNA fragmentation and its counteraction by GSPE in the liver was also evaluated quantitatively (by a sedimentation assay) and qualitatively (by agarose gel electrophoresis). Portions of livers were also subjected to Western blot analysis (27,000g fraction of liver homogenates) to examine the pattern of expression of cell death inhibitory gene bcl-Xl. Results indicate that 7-day GSPE preexposure induced dramatic protection and markedly decreased liver injury and animal lethality culminated by AAP, when compared to a short-term 3-day exposure. Abrogation of toxicity was also mirrored in DNA fragmentation. Histopathological evaluation of liver sections showed remarkable counteraction of AAP-toxicity by this novel GSPE and substantial inhibition of both apoptotic and necrotic liver cell death. Agarose gel electrophoresis revealed that 7-day GSPE preexposure prior to AAP administration completely blocked Ca(2+)/Mg(2+)-Ca(2+)/Mg(2+)-dependent-endonuclease-mediated ladder-like fragmentation of genomic DNA and significantly altered the bcl-Xl expression. The most dramatic changes observed in this study were: (i) substantial increase in the expression of bcl-Xl in the liver by 7-day GSPE exposure alone; (ii) significant modification bcl-Xl expression by AAP alone; and (iii) dramatic inhibition of AAP-induced modification of bcl-Xl (phosphorylation?) expression by GSPE. In summary, these observations demonstrate that GSPE preexposure may significantly attenuate AAP-induced hepatic DNA damage, apoptotic and necrotic cell death of liver cells, and, most remarkably, antagonize the influence of AAP-induced changes in bcl-Xl expression in vivo.

Cardioprotective effects of grape seed proanthocyanidin against ischemic reperfusion injury

There is increasing evidence to indicate cardioprotective effects of red wine consumption. Such cardioprotective properties of wine have been attributed to certain polyphenolic constituents of grapes. The purpose of this investigation was to examine whether proanthocyanidins derived from grape seeds possess cardioprotective properties. Rats were randomly divided into two groups: grape-seed proanthocyanidin was administered orally to one group of rats (100 mg/kg/day) for 3 weeks while the other group served as control. After 3 weeks, rats were killed, hearts excised, mounted on the perfusion apparatus and perfused with Krebs-Henseleit bicarbonate (KHB) buffer. After stabilization hearts were perfused in the working mode for baseline measurements of contractile functions. Hearts were then subjected to 30 min of global ischemia followed by 2 h of reperfusion. Coronary perfusates were collected to monitor malonaldehyde formation, a presumptive marker for oxidative stress development. At the end of each experiment, the heart was processed for infarct size determination. Peroxyl radical scavenging activity of proanthocyanidin was determined by examining its ability to remove peroxyl radical generated by 2,2'-azobis (2-amidinopropane) dihydrochloride while hydroxyl radical scavenging activity was tested with its ability to reduce 7-OH.-coumarin-3-carboxylic acid. The results of our study demonstrated that proanthocyanidin-fed animals were resistant to myocardial ischemia reperfusion injury as evidenced by improved recovery of post-ischemic contractile functions. The proanthocyanidin-fed group revealed reduced extent of myocardial infarction compared to the control group. Fluorimetric study demonstrated the antioxidant property of proanthocyanidin as judged by its ability to directly scavenge peroxyl radicals. Taken together, the results of this study showed that grape seed-proanthocyanidins possess a cardioprotective effect against ischemia reperfusion injury. Such cardioprotective property, at least in part, may be attributed to its ability to directly scavenge peroxyl and hydroxyl radicals and to reduce oxidative stress developed during ischemia and reperfusion.

The cytotoxic effects of a novel IH636 grape seed proanthocyanidin extract on cultured human cancer cells

Grape seed proanthocyanidins are natural antioxidants which possess a broad spectrum of chemoprotective properties against free radicals and oxidative stress. In this study, we have assessed the cytotoxicity of a novel IH636 grape seed proanthocyanidin extract (GSPE) against MCF-7 human breast cancer cells, A-427 human lung cancer cells, CRL-1739 human gastric adenocarcinoma cells and K562 chronic myelogenous leukemic cells at 25 and 50 mg/lit concentrations for 0-72 h using cytomorphology and MTT cytotoxicity assay. In addition, we compared the effects on normal human gastric mucosal cells and normal J774A.1 murine macrophage cells with the effects on the cancer cell lines. Concentration- and time-dependent cytotoxic effects of GSPE were observed on the MCF-7 breast cancer, A-427 lung cancer and gastric adenocarcinoma cells. Following incubation of the MCF-7 cells with 25 mg/lit of the GSPE approximately 6.5, 30 and 43% inhibitions in cell growth were observed at 24, 48 and 72 h of incubation, respectively, while incubation of the MCF-7 cells with 50 mg/lit of the GSPE resulted in 11, 35 and 47% inhibition in cell growth at these same points, respectively. Similar results were observed in the A-427 and gastric adenocarcinoma cells. GSPE exhibited no cytotoxicity toward the neoplastic K562 myelogenous leukemic cells. However, GSPE enhanced the growth and viability of the normal human gastric mucosal cells and J774A.1 murine macrophage cells. These data demonstrate that GSPE exhibited cytotoxicity towards some cancer cells, while enhancing the growth and viability of the normal cells which were examined.

Acute and chronic stress-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate

Reactive oxygen species (ROS) are implicated in the pathogenesis of stress-induced gastrointestinal mucosal injury. In the present study, we have investigated the effects of acute and chronic stress on the enhanced production of ROS including superoxide anion [SA; as determined by cytochrome c reduction (CCR)] and hydroxyl radicals (OH), and correlated the enhanced production of these free radicals with increased lipid peroxidation, membrane microviscosity and DNA fragmentation, indices of oxidative tissue damage, in the gastric and intestinal mucosa of female Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS) against the gastrointestinal mucosal injury induced by acute and chronic stress was determined. Acute stress was induced for a period of 90 min, while chronic stress was induced for 15 min/day for 15 consecutive days. Half of the animals exposed to acute stress were pretreated orally with 15 mg BSS/kg 30 min prior to the exposure to acute stress. Similarly, half of the animals exposed to water-immersion restraint chronic stress were pretreated orally with 7.5 mg BSS/kg/day for 15 consecutive days 30 min prior to the exposure to chronic stress. Acute stress produced greater injury to both gastric and intestinal mucosa as compared to chronic stress. Acute stress increased CCR and OH production by 10.0- and 14.3-fold, respectively, in the gastric mucosa, and 10.4- and 17.0-fold, respectively, in the intestinal mucosa. Pretreatment with BSS prevented the acute stress-induced increase in CCR and OH production. Acute stress increased lipid peroxidation, DNA fragmentation and membrane microviscosity by 3.6-, 4.0- and 11.6-fold, respectively, in gastric mucosa, and 4.1-, 5.0- and 16.2-fold, respectively, in intestinal mucosa. BSS decreased acute stress-induced lipid peroxidation, DNA fragmentation and membrane microviscosity by approximately 26, 35 and 30%, respectively, in gastric mucosa, and by 20, 36 and 30%, respectively, in the intestinal mucosa. Chronic stress increased CCR and OH production by 4.8- and 6.3-fold, respectively, in gastric mucosa, and 4.6- and 6.9-fold, respectively, in intestinal mucosa. Chronic stress increased lipid peroxidation and DNA fragmentation by 2.9- and 3.3-fold, respectively, in gastric mucosa, and 3.3- and 4.2-fold, respectively, in intestinal mucosa. BSS decreased chronic stress-induced lipid peroxidation, DNA fragmentation and membrane microviscosity by approximately 41, 44 and 45%, respectively, in gastric mucosa, and by 39, 52 and 51%, respectively, in the intestinal mucosa. Daily administration of BSS provided greater protection against chronic stress-induced oxidative gastrointestinal injury as compared to the acute stress. These results demonstrate that both acute and chronic stress can induce gastrointestinal mucosal injury through enhanced production of ROS, and that BSS can significantly protect against gastrointestinal mucosal injury.

Providing mifepristone-misoprostol medical abortion: the view from the clinic

In order to gather information about the practical aspects of offering medical abortion, we conducted focus group discussions at each of 17 sites participating in the first large-scale, multi-center trial of mifepristone-misoprostol abortion in the United States. The sites were chosen to represent diverse practice settings (Planned Parenthood affiliates, university research clinics, private practices, and feminist health centers) and geographical regions. Seventy-seven clinic staff members (including counselors, administrators, physicians and other health workers) participated. They discussed the impact of adding a medical method to their clinic structure, their own preferences about offering the method, and their perceptions of women's preferences. Staffing a medical abortion service requires different skills and temperament than those needed for a surgical service. Nearly all participants were eager to begin offering the medical method, and they perceived a strong demand for it on the part of women. They had mixed feelings about the type of provider who should offer the method, but nearly all felt that the regimen could be greatly simplified from the three-visit regimen tested in the trial.

The survey form of SCAN: the feasibility of using experienced lay survey interviewers to administer a semi-structured systematic clinical assessment of psychotic and non-psychotic disorders

BACKGROUND

The success of large scale surveys depends on well designed questionnaires and the skills of lay interviewers. Discrepancies in prevalence rates between epidemiological surveys and poor agreement between survey interviewer and clinician diagnostic interviews are giving rise to increasing concern among researchers, public health planners and policy developers. New approaches to information collection are called for. The feasibility of training experienced survey interviewers in semi-structured, clinical, diagnostic interviewing has never been investigated systematically across the range of neurotic and psychotic disorders.

METHODS

Eight experienced survey interviewers from the Office for National Statistics (ONS) were selected and underwent extended training in a Survey Form of SCAN (SCAN-SF). Sixty-four adults, including a majority of psychiatric in-patients were assessed by ONS interviewers and reinterviewed within a week by SCAN-trained clinicians. Feedback was sought from interviewers and trainers.

RESULTS

Trainers found lay interviewers coped at least as well with psychotic as with neurotic symptoms. Concordance for any disorder was 0.74 (95% CI: 0.57 to 0.91); for any specific psychotic disorder 0.63 (0.40 to 0.86); for any specific neurotic disorder 0.63 (0.43 to 0.83). Sensitivity ranged from 0.6 to 0.9 and specificity from 0.8 to 0.9. There was no evidence of rater bias.

CONCLUSIONS

These preliminary findings are very promising. However, before the SCAN-SF, administered by carefully trained lay interviewers, can be recommended in large scale surveys, further evaluations of its feasibility and reliability in the general population are needed.

Smokeless tobacco, oxidative stress, apoptosis, and antioxidants in human oral keratinocytes

We have investigated the effects of a smokeless tobacco extract (STE) on lipid peroxidation, cytochrome c reduction, DNA fragmentation and apoptotic cell death in normal human oral keratinocyte cells, and assessed the protective abilities of selected antioxidants. The cells, isolated and cultured from human oral tissues, were treated with STE (0-300 microl;g/ml) for 24 h. Superoxide anion production was determined by cytochrome c reductase. Oxidative tissue damage was determined by lipid peroxidation and DNA fragmentation, whereas apoptotic cell death was assessed by flow cytometry. STE-induced fragmentation of genomic DNA was also determined by gel electrophoresis. The comparative protective abilities of vitamin C (75 microM), vitamin E (75 microM), a combination of vitamins C & E (75 microM each), and a novel grape seed proanthocyanidin (IH636) extract (GSPE) (100 microg/ml) against STE induced oxidative stress and tissue damage were also determined. Following treatment of the cells with 300 microg STE/ml 1.5-7.6-fold increases in lipid peroxidation, cytochrome c reduction and DNA fragmentation were observed. The addition of the antioxidants to cells treated with STE provided 10-54% decreases in these parameters. Approximately 9, 29, and 35% increases in apoptotic cell death were observed following treatment with 100, 200, and 300 microg STE/ml, respectively, and 51-85% decreases in apoptotic cell death were observed with the antioxidants. The results demonstrate that STE produces oxidative tissue damage and apoptosis, which can be attenuated by antioxidants including vitamin C, vitamin E, a combination of vitamins C plus E and GSPE. GSPE exhibited better protection against STE than vitamins C and E, singly and in combination.

Amelioration of the cytotoxic effects of chemotherapeutic agents by grape seed proanthocyanidin extract

Anticancer chemotherapeutic agents are effective in inhibiting growth of cancer cells in vitro and in vivo, however, toxicity to normal cells is a major problem. In this study, we assessed the effect of a novel IH636 grape seed proanthocyanidin extract (GSPE) to ameliorate chemotherapy-induced toxic effects in cultured Chang epithelial cells, established from nonmalignant human tissue. These cells were treated in vitro with idarubicin (Ida) (30 nM) or 4-hydroxyperoxycyclophosphamide (4HC) (1 microg/ml) with or without GSPE (25 microg/ml). The cells were grown in vitro and the growth rate of the cells was determined using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; thiazolyl blue] assay. Our results showed that GSPE decreased the growth inhibitory and cytotoxic effects of Ida as well as 4HC on Chang epithelial cells in vitro. Because these chemotherapeutic agents are known to induce apoptosis in the target cells, we analyzed the Chang epithelial cells for apoptotic cell population by flow cytometry. There was a significant decrease in the number of cells undergoing apoptosis following treatment with GSPE. We also found increased expression of the anti-apoptotic protein Bcl-2 in GSPE-treated cells using western blot techniques. Thus, these results indicate that GSPE can be a potential candidate to ameliorate the toxic effects associated with chemotherapeutic agents and one of the mechanisms of action of GSPE includes upregulation of Bcl-2 expression.

Detection of oxidative DNA damage to ischemic reperfused rat hearts by 8-hydroxydeoxyguanosine formation

Reactive oxygen species that are generated in the ischemic heart upon reperfusion, play a significant role in the pathogenesis of reperfusion injury. Although DNA is a well known target for free radical attack, little attention has been paid to the injury of DNA molecules associated with ischemia and reperfusion. In this study, the formation of 8-hydroxydeoxyguanosine (8-OHDG), a product of hydroxyl radical (OH.)-DNA interaction, was monitored in the post-ischemic myocardium. A simple high performance liquid chromatography (HPLC), with uv detection, detected pmol levels of 8-OHDG in the pre-ischemic heart which increased steadily and progressively as a function of reperfusion time. A similar rise in 8-OHDG was noticed when isolated hearts were perfused with a OH. -generating system. Corroborating with the increased 8-OHDG formation, increased amount of creatine kinase was released from the coronary effluent indicating increased tissue injury. The formation of 8-OHDG was completely blocked when hearts were preperfused with oxygen-free-radical scavenger, 1,3-dimethyl-2-thiourea (DMTU) which also significantly reduced the appearance of CK in the coronary effluent, suggesting that oxidative DNA damage play a role in the pathophysiology of ischemic reperfusion injury.

Protective ability of acetylsalicylic acid (aspirin) to scavenge radiation induced free radicals in J774A.1 macrophage cells

Radiation generates a variety of free radicals during the exposure of biological tissues through radiolysis of water. These free radicals are highly reactive and cause oxidative damage to biological molecules. This study examined the protective ability of aspirin against radiation induced oxidative stress. The study assessed the protective effect of aspirin (0.05 mM, 0.10 mM, 0.50 mM) on the generation of free radicals during exposure of J774A.1 macrophage cells to radiation (13.25 cGy). Approximately a 2.2-fold increase in superoxide anion formation as determined by cytochrome c reduction was observed following exposure of the cells to radiation for 20 one second exposures. Preincubation with aspirin exhibited a dose dependent decrease in free radical production as assessed by chemiluminescence and cytochrome c reduction. Aspirin also produced a concentration dependent reduction in radiation induced DNA damage in the cells. The data indicate that radiation of these cells results in production of reactive oxygen species and DNA damage, and aspirin can decrease these effects in a concentration dependent manner.

Induction of oxidative stress and DNA damage by chronic administration of naphthalene to rats

Naphthalene is a bicyclic aromatic compound that is widely used in various domestic and commercial applications including lavatory scent disks, soil fumigants and moth balls. Little information is available regarding the mechanism of naphthalene toxicity. We have assessed the oral, low dose (0.05 LD50) chronic effects of naphthalene (110 mg/kg/day p.o. in corn oil) for 120 consecutive days on lipid peroxidation and DNA fragmentation in the liver and brain tissues of female Sprague-Dawley rats. The animals were sacrificed on 0, 15, 30, 45, 60, 75, 90, 105 and 120 days of treatment. Maximum increases in hepatic and brain lipid peroxidation and DNA fragmentation were observed between 90 and 105 days of treatment. Following administration of naphthalene for 90 days, approximately 1.4- and 1.3-fold increases in lipid peroxidation were observed in the hepatic and brain tissues, respectively, while under the same conditions and time points 1.9- and 2.5-fold increases in hepatic and brain DNA fragmentation were observed, respectively. These results demonstrate that low dose chronic administration of naphthalene induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of naphthalene.

Naphthalene-induced oxidative stress and DNA damage in cultured macrophage J774A.1 cells

Naphthalene is a bicyclic aromatic compound that is widely used in various domestic and commercial applications including lavatory scent disks, soil fumigants and moth balls. However, little information is available regarding the mechanism of naphthalene toxicity. We have assessed the concentration-dependent in vitro effects of naphthalene on increased lipid peroxidation, cytochrome c reduction, hydroxyl radical production, modulation of intracellular oxidized states by laser scanning confocal microscopy, and DNA fragmentation in cultured macrophage J774A.1 cells. The cells were incubated with 0-500 microM concentrations of naphthalene for 0, 12 and 24 h at 37 degrees C. Concentration- and time-dependent changes were observed. No significant changes were observed with concentrations of naphthalene up to 100 microM. At 24 h, lipid peroxidation increased by 1.8-, 2.4- and 2.9-fold at 200, 300 and 500 microM concentrations of naphthalene. Approximately 2.0-, 3.1- and 4.6-fold increases in cytochrome c reduction were observed at 200, 300 and 500 microM concentrations of naphthalene, respectively, at this time point demonstrating the production of superoxide anion, while under the same conditions approximately 2.4-, 3.2- and 4.9-fold increases in hydroxyl radical production were observed, respectively. Following incubation of these cells with 200 and 500 microM concentrations of naphthalene 2.3- and 4.7-fold increases in fluorescence intensity were observed, respectively, as compared to the untreated cells. At 24 h, approximately 1.8-, 2.3- and 3.0-fold increases in DNA fragmentation were observed following incubation with 200, 300 and 500 microM concentrations of naphthalene, respectively. Naphthalene also produced concentration- dependent decreases in cell viability. At the 12 h time point, significant changes were observed only with 300 and 500 microM concentrations of naphthalene. These results demonstrate that naphthalene may induce toxic manifestations by enhanced production of oxygen free radicals, resulting in lipid peroxidation and DNA damage.

Subchronic effects of smokeless tobacco extract (STE) on hepatic lipid peroxidation, DNA damage and excretion of urinary metabolites in rats

The oral use of moist smokeless tobacco products (snuff) is causally associated with cancer of the mouth, lip, nasal cavities, esophagus and gut. The mechanism by which smokeless tobacco constituents produce genetic and tissue damage is not known. Recent studies in our laboratories have shown that an aqueous extract of smokeless tobacco (STE) activates macrophages with the resultant production of reactive oxygen species (ROS), including nitric oxide. Furthermore, the administration of acute doses of STE (125-500 mg/kg) to rats induces dose dependent increases in mitochondrial and microsomal lipid peroxidation, enhances DNA single strand breaks, and significantly increases the urinary excretion of the lipid metabolites malondialdehyde, formaldehyde, acetaldehyde and acetone. Since the use of tobacco is a chronic process, the effects of an aqueous extract of STE in rats following low dose exposure were examined. Female Sprague-Dawley rats were treated orally with 25 mg STE/kg every other day for 105 days. The effects of subchronic treatment of STE on hepatic microsomal and mitochondrial lipid peroxidation and the incidence of hepatic nuclear DNA damage were assessed. Lipid peroxidation increased 1.4- to 3.3-fold in hepatic mitochondria and microsome with STE treatment between 0 and 105 days with respect to control animals while hepatic DNA single strand breaks increased up to 3.4-fold. Maximum increases in lipid peroxidation and DNA single strand breaks occurred between 75 and 90 days of treatment. Urinary excretion of the four lipid metabolites malondialdehyde, formaldehyde, acetaldehyde and acetone was monitored by high pressure liquid chromatography (HPLC) with maximum increases being observed between 60 and 75 days of treatment. The results clearly indicate that low dose subchronic administration of STE induces an oxidative stress resulting in tissue damaging effects which may contribute to the toxicity and carcinogenicity of STE.

Stress, diet and alcohol-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate

Oxygen free radicals are implicated in the pathogenesis of stress and food/alcohol-induced gastrointestinal injury. We have investigated the effects of restraint stress, spicy food diet, high-fat diet and 40% ethanol on the enhanced production of reactive oxygen species, including superoxide anion and hydroxyl radicals, and on DNA fragmentation, lipid peroxidation and membrane microviscosity (indices of oxidative tissue damage) in gastric and intestinal mucosa of Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS; 15 mg kg(-1) was determined against the gastrointestinal mucosal injury induced by these stressors. Animals on the high-fat diet consumed 31% more food as compared to other animals. Animals on the spicy food diet consumed ca. 23% more water as compared to control animals, and the high-fat diet animals consumed 17% less water. Restraint stress provided greater injury to both gastric and intestinal mucosa as compared to other stressors. Restraint stress, spicy food diet, high-fat diet and ethanol increased superoxide anion production by 10.0-, 4.3-, 5.7- and 4.8-fold, respectively, in the gastric mucosa, and by 10.4-, 5.3-, 7.0- and 5.5-fold in the intestinal mucosa. Exposure to restraint stress, spicy food diet, high-fat diet and 40% ethanol also increased hydroxyl radical production by ca. 14.3-, 4.5-, 3.5- and 4.8-fold, respectively, in the gastric mucosa, and by 17.0-, 4.8-, 3.5- and 4.7-fold in the intestinal mucosa. Bismuth subsalicylate administration to the animals provided significant protection against superoxide anion and hydroxyl radical production. Restraint stress, spicy food diet, high-fat diet and ethanol increased lipid peroxidation by 3.6-, 2.4-, 2.6- and 2.0-fold, respectively, in the gastric mucosa, and by 4.1-, 3.5-, 3.6- and 2.7-fold in intestinal mucosa. Administration of BSS decreased restraint stress, spicy food diet, high-fat diet and ethanol-induced gastric mucosal lipid peroxidation by ca. 26%, 36%, 45% and 18%, and intestinal mucosa lipid peroxidation by 20%, 21%, 46% and 42%, respectively. Approximately 4.0-, 2.0-, 2.4- and 2.0-fold increases in DNA fragmentation were observed in the gastric mucosa of rats exposed to restraint stress, spicy food diet, high-fat diet and 40% ethanol, respectively, and similar increases in the intestinal mucosa. These same four stressors increased membrane microviscosity by 11.6-, 6.1-, 7.3- and 5.4-fold, respectively, in the gastric mucosa, and by 16.2-, 7.9-, 9.5- and 7.8-fold in the intestinal mucosa. Bismuth subsalicylate exerted significant protection against DNA damage and changes in membrane microviscosity induced by the four stressors. Excellent correlations existed between the production of reactive oxygen species and the tissue damaging effects in both gastric and intestinal mucosa. In summary, the results demonstrate that physical and chemical stressors can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of reactive oxygen species, and that BSS can significantly attenuate gastrointestinal injury by scavenging these reactive oxygen species.

Protective effects of grape seed proanthocyanidins and selected antioxidants against TPA-induced hepatic and brain lipid peroxidation and DNA fragmentation, and peritoneal macrophage activation in mice

1. The comparative protective abilities of a grape seed proanthocyanidin extract (GSPE) (25-100 mg/kg), vitamin C (100 mg/kg), vitamin E succinate (VES) (100 mg/kg) and beta-carotene (50 mg/kg) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation and DNA fragmentation in the hepatic and brain tissues, as well as production of reactive oxygen species by peritoneal macrophages, were assessed. 2. Treatment of mice with GSPE (100 mg/kg), vitamin C, VES and beta-carotene decreased TPA-induced production of reactive oxygen species, as evidenced by decreases in the chemiluminescence response in peritoneal macrophages by approximately 70%, 18%, 47% and 16%, respectively, and cytochrome c reduction by approximately 65%, 15%, 37% and 19%, respectively, compared with controls. 3. GSPE, vitamin C, VES and beta-carotene decreased TPA-induced DNA fragmentation by approximately 47%, 10%, 30% and 11%, respectively, in the hepatic tissues, and 50%, 14%, 31% and 11%, respectively, in the brain tissues, at the doses that were used. Similar results were observed with respect to lipid peroxidation in hepatic mitochondria and microsomes and in brain homogenates. 4. GSPE exhibited a dose-dependent inhibition of TPA-induced lipid peroxidation and DNA fragmentation in liver and brain, as well as a dose-dependent inhibition of TPA-induced reactive oxygen species production in peritoneal macrophages. 5. GSPE and other antioxidants provided significant protection against TPA-induced oxidative damage, with GSPE providing better protection than did other antioxidants at the doses that were employed.

Stress, diet and alcohol-induced oxidative gastrointestinal mucosal injury in rats and protection by bismuth subsalicylate

Oxygen free radicals are implicated in the pathogenesis of stress and food/alcohol-induced gastrointestinal injury. We have investigated the effects of restraint stress, spicy food diet, high-fat diet and 40% ethanol on the enhanced production of reactive oxygen species, including superoxide anion and hydroxyl radicals, and on DNA fragmentation, lipid peroxidation and membrane microviscosity (indices of oxidative tissue damage) in gastric and intestinal mucosa of Sprague-Dawley rats. Furthermore, the protective ability of bismuth subsalicylate (BSS; 15 mg kg(-1) was determined against the gastrointestinal mucosal injury induced by these stressors. Animals on the high-fat diet consumed 31% more food as compared to other animals. Animals on the spicy food diet consumed ca. 23% more water as compared to control animals, and the high-fat diet animals consumed 17% less water. Restraint stress provided greater injury to both gastric and intestinal mucosa as compared to other stressors. Restraint stress, spicy food diet, high-fat diet and ethanol increased superoxide anion production by 10.0-, 4.3-, 5.7- and 4.8-fold, respectively, in the gastric mucosa, and by 10.4-, 5.3-, 7.0- and 5.5-fold in the intestinal mucosa. Exposure to restraint stress, spicy food diet, high-fat diet and 40% ethanol also increased hydroxyl radical production by ca. 14.3-, 4.5-, 3.5- and 4.8-fold, respectively, in the gastric mucosa, and by 17.0-, 4.8-, 3.5- and 4.7-fold in the intestinal mucosa. Bismuth subsalicylate administration to the animals provided significant protection against superoxide anion and hydroxyl radical production. Restraint stress, spicy food diet, high-fat diet and ethanol increased lipid peroxidation by 3.6-, 2.4-, 2.6- and 2.0-fold, respectively, in the gastric mucosa, and by 4.1-, 3.5-, 3.6- and 2.7-fold in intestinal mucosa. Administration of BSS decreased restraint stress, spicy food diet, high-fat diet and ethanol-induced gastric mucosal lipid peroxidation by ca. 26%, 36%, 45% and 18%, and intestinal mucosa lipid peroxidation by 20%, 21%, 46% and 42%, respectively. Approximately 4.0-, 2.0-, 2.4- and 2.0-fold increases in DNA fragmentation were observed in the gastric mucosa of rats exposed to restraint stress, spicy food diet, high-fat diet and 40% ethanol, respectively, and similar increases in the intestinal mucosa. These same four stressors increased membrane microviscosity by 11.6-, 6.1-, 7.3- and 5.4-fold, respectively, in the gastric mucosa, and by 16.2-, 7.9-, 9.5- and 7.8-fold in the intestinal mucosa. Bismuth subsalicylate exerted significant protection against DNA damage and changes in membrane microviscosity induced by the four stressors. Excellent correlations existed between the production of reactive oxygen species and the tissue damaging effects in both gastric and intestinal mucosa. In summary, the results demonstrate that physical and chemical stressors can induce gastrointestinal oxidative stress and mucosal injury through enhanced production of reactive oxygen species, and that BSS can significantly attenuate gastrointestinal injury by scavenging these reactive oxygen species.

Protective effects of zinc salts on TPA-induced hepatic and brain lipid peroxidation, glutathione depletion, DNA damage and peritoneal macrophage activation in mice

1. The comparative protective abilities of zinc L-methionine, zinc DL-methionine, zinc sulfate, zinc gluconate, L-methionine, DL-methionine, and vitamin E succinate (VES) on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lipid peroxidation, DNA fragmentation, and glutathione depletion in the hepatic and brain tissues, and production of reactive oxygen species by peritoneal macrophages were assessed. In addition, mice were fed a zinc-deficient diet for 5 weeks, and treated with TPA and/or zinc L-methionine or zinc DL-methionine, and similar studies were conducted. 2. The zinc-deficient diet induced oxidative stress in the hepatic and brain tissues as well as in the peritoneal macrophages as evidenced by significantly enhanced lipid peroxidation. DNA fragmentation, glutathione depletion, and production of reactive oxygen species. 3. Treatment of mice with zinc L-methionine, zinc DL-methionine, and VES decreased TPA-induced reactive oxygen species production as evidenced by significant decreases in chemiluminescence in peritoneal macrophages by approximately 45%, 31%, and 47%, respectively, and cytochrome c reduction by approximately 54%, 35%, and 41%, respectively, as compared with control values. Similar results were observed with liver and brain lipid peroxidation, DNA fragmentation, and glutathione depletion. 4. Zinc salts and antioxidants provided significant protection against TPA-induced oxidative damage. Zinc L-methionine provided the best protection.

Chronic effects of smokeless tobacco extract on rat liver histopathology and production of HSP-90

Tobacco consumption is a worldwide problem. The recent increase in the consumption of the smokeless tobacco products (snuff and chewing tobacco) has stimulated interest into the carcinogenic effects of these forms of tobacco. The use of smokeless tobacco products has increased in popularity as the use of cigarettes has become less socially acceptable. For most individuals the use of tobacco is a chronic process. Therefore, the effects of an aqueous extract of smokeless tobacco (STE) in rats following low-dose exposure were examined. Female Sprague-Dawley rats were treated orally with 25 mg STE/kg every other day for 90 days. In order to obtain information regarding the cytotoxicity of STE, the ultrastructural changes occurring in livers of rats following administration of STE were examined under light and electron microscopy. Electron microscopy revealed that in the perisinusoidal spaces an accumulation of indistinct filamentous material occurred following 60 days of treatment, occupying most of the sinusoids. Moreover, the lipids were in a state of disintegration. Significant increases in 90 kDa protein expression were also observed due to chronic treatment with STE. Western blot analysis using a polyclonal mouse antibody against heat shock/stress protein 90 (HSP90) confirmed that the overexpressed proteins were heat shock/stress proteins (HSPs). The HSPs are believed to serve as adaptive or survival functions involving a rapid but transient reprogramming of cellular metabolic activity to protect cells from oxidative damage.

Comparative induction of oxidative stress in cultured J774A.1 macrophage cells by chromium picolinate and chromium nicotinate

The concentration-dependent effects of chromium picolinate and chromium nicotinate were assessed on the enhanced production of reactive oxygen species including superoxide anion and hydroxyl radicals, and lipid peroxidation and DNA fragmentation in cultured macrophage J774A.1 cells. The macrophage cells were incubated with 0-50 micrograms/ml [corrected] concentrations of these chromium (III) salts for 0 and 24 hrs at 37 degrees C. Concentration-dependent effects were observed. Lipid peroxidation increased by 1.3-1.5-fold following treatment of these cells with chromium picolinate while at these same concentrations of chromium nicotinate approximately 1.2-1.8-fold increases in lipid peroxidation were observed. Increases of 1.0-1.5-fold occurred in the production of superoxide anion as determined by cytochrome c reduction following treatment with chromium picolinate while with these same concentrations and conditions only 1.1-1.2-fold increases in cytochrome c reduction were observed following treatment with chromium nicotinate. Approximately 1.2-1.5-fold increases in hydroxyl radical production were observed following treatment of these macrophage cells with increasing concentrations of chromium picolinate and chromium nicotinate. Incubation of the cells with 30-50 micrograms/ml concentrations of chromium picolinate produced 1.2-1.6 fold increases in DNA fragmentation, while under these same conditions with chromium nicotinate 1.2-1.3-fold increases in DNA fragmentation occurred. No significant loss in cell viability was observed with either chromium salt. These results demonstrate that incubation of macrophage J774A.1 cells with these chromium salts induces low levels of oxidative stress as demonstrated by the biochemical assay techniques employed in this study.

Protection against chemically-induced oxidative gastrointestinal tissue injury in rats by bismuth salts

Oxygen free radicals (OFR) are implicated in the pathogenesis of stress, chemically induced gastric lesions, and gastrointestinal injury. The concentration-dependent scavenging abilities of bismuth subsalicylate (SBS), colloidal bismuth subcitrate (CBS), and selected OFR scavengers, including superoxide dismutase (SOD), catalase, mannitol, and allopurinol were examined against biochemically or chemically generated superoxide anion, hydroxyl radical, and hypochlorite radical plus hypochlorous acid based on a chemiluminescence assay. Furthermore, both gastric (GM) and intestinal mucosa (IM) were individually exposed in vitro to these free radical generating systems, and the concentration-dependent protective abilities of SBS and CBS against lipid peroxidation (LP) were compared with selected OFR scavengers. In addition, 24-hr fasted rats were orally treated with the necrotizing agents 0.6 M HCl, 0.2 M NaOH, 80% ethanol, and aspirin (200 mg/kg). The extent of tissue injury in the GM and IM was determined by assessing LP, DNA fragmentation, and membrane microviscosity. Dose- and time-dependent in vivo protective abilities of CBS (100 mg/kg) and SBS (15 mg/kg) were also assessed. Following incubations with superoxide anion and hydroxyl radical generating systems in the presence of 125 mg SBS/liter, approximately 47% and 61% inhibitions were observed in the chemiluminescence response, respectively, while 48% and 46% inhibitions were observed with 125 mg CBS/liter. SBS and CBS exerted similar abilities towards hypochlorite radical plus hypochlorous acid. Approx. 3.1- and 3.7-fold increases in LP were observed in the GM and IM of rats following oral administration of 0.6 M HCl. Pretreatment of the rats with SBS and CBS decreased 0.6 M HCl-induced LP in the GM by approx. 39% and 27%, respectively, with similar decreases in LP in the IM. SBS exhibited better protective abilities towards 0.6 M HCl and 0.2 m NaOH-induced GM and IM injury as compared to CBS. SBS and CBS provided similar protection towards 80% ethanol-induced gastric injury, while CBS exerted a superior protective ability towards aspirin-induced gastric injury. The results demonstrate that both SBS and CBS can scavenge reactive oxygen species and prevent tissue damage produced by OFR.

Interrelationship between cellular calcium homeostasis and free radical generation in myocardial reperfusion injury

This review describes the interrelationship between two important biological factors, intracellular calcium overloading and oxygen-derived free radicals, which play a crucial role in the pathogenesis of myocardial ischemic reperfusion injury. Free radicals are generated during the reperfusion of ischemic myocardium, and polyunsaturated fatty acids in the membrane phospholipids are the likely targets of the free radical attack. On the other hand, activation of phospholipases can provoke the breakdown of membrane phospholipids which results in the activation of arachidonate cascade leading to the generation of prostaglandins, and oxygen free radicals can be produced during the interconversion of the prostaglandins. In conclusion, it has been emphasized that the two seemingly different causative factors of reperfusion injury, intracellular calcium overloading and free radical generation are, in fact, highly interrelated.

Comparative in vitro and in vivo protein kinase C activation by selected pesticides and transition metal salts

Various pesticides and transition metals induce oxidative deterioration of biological macromolecules. Protein kinase C (PKC) may mediate these effects. However, no information is available regarding whether these xenobiotics can modulate PKC which is a critical event signaling the increase in endothelial permeability and cell proliferation. Female Sprague-Dawley rats were treated p.o. with two 0.25 LD50 doses of selected pesticides and transition metal salts at 0 and 21 h, and killed at 24 h. PKC activities were measured in liver and brain tissues. Cultured PC-12 cells were incubated for 24 h with 50, 100 or 200 nM concentrations of these pesticides, while 0.20, 0.40 or 0.60 microM concentrations of cadmium chloride (Cd(II)) and sodium dichromate (Cr(VI)) salts were employed. PKC activations were observed in the hepatic and brain cytosol fractions by all xenobiotics. Approximately 1.4- to 2.0-fold and 1.6- to 3.5-fold increases in PKC activity in the hepatic and brain cytosol fractions were observed, respectively. In the hepatic tissues, the greatest increases in activities were observed with TCDD, chlorpyrifos, endrin and Cd(II), while chlorpyrifos and fenthion exerted the greatest increases in the brain tissues. In cultured PC-12 cells, the greatest activation of PKC was observed primarily with 100-nM concentrations of the pesticides. The maximum effects were induced by chlorpyrifos, fenthion, Cd(II) and Cr(VI) salt. The results clearly indicate that pesticides as well as Cd(II) and Cr(VI) salts can modulate a vital component of the cell signaling pathway, namely PKC activity. PKC may be a target of free radicals and oxidative stress, leading to altered cell proliferation and differentiation.

Oxygen free radical scavenging abilities of vitamins C and E, and a grape seed proanthocyanidin extract in vitro

Proanthocyanidins, a group of polyphenolic bioflavonoids, have been reported to exhibit a wide range of biological, pharmacological and chemoprotective properties against oxygen free radicals. We have assessed the concentration-dependent oxygen free radical scavenging abilities of a grape seed proanthocyanidin extract (GSPE), vitamin C and vitamin E succinate (VES) as well as superoxide dismutase, catalase and mannitol against biochemically generated superoxide anion and hydroxyl radical using a chemiluminescence assay and cytochrome c reduction. A concentration-dependent inhibition was demonstrated by GSPE. At a 100 mg/l concentration, GSPE exhibited 78-81% inhibition of superoxide anion and hydroxyl radical. Under similar conditions, vitamin C inhibited these two oxygen free radicals by approximately 12-19%, while VES inhibited the two radicals by 36-44%. The combination of superoxide dismutase and catalase inhibited superoxide anion by approximately 83%, while mannitol resulted in an 87% inhibition of hydroxyl radical. The results demonstrate that GSPE is a more potent scavenger of oxygen free radicals as compared to vitamin C and VES.

Comparative in vitro oxygen radical scavenging ability of zinc methionine and selected zinc salts and antioxidants

1. The concentration-dependent scavenging abilities of zinc DL-methionine, zinc sulfate, zinc gluconate, zinc picolinate and selected free radical scavengers, including superoxide dismutase (SOD), catalase, mannitol, allopurinol and DL-methionine, were examined against biochemically generated superoxide anion, hydroxyl radical and hypochlorite radical plus hypochlorous acid, by chemiluminescence and cytochrome c reduction. 2. Zinc methionine was the most effective of the zinc compounds that were tested. Following incubations with superoxide anion, hydroxyl radical, and hypochlorite radical-generating systems, in the presence of 50 microM zinc DL-methionine approximately 38%, 47% and 28% inhibition in reactive oxygen species generation was observed, respectively, compared to control groups. 3. The protective abilities of various zinc salts, as well as selected free radical scavengers and antioxidants were also assessed on phorbol ester (TPA)-induced lactate dehydrogenase (LDH) release from cultured PC-12 cells. Preincubation showed better protection than coincubation. Approximately 45% and 50% inhibition in TPA-induced LDH leakage was observed following preincubation with 50 microM zinc DL-methionine and 50 microM vitamin E succinate, respectively. Zinc DL-methionine exhibited better protection against LDH leakage than any other zinc salt tested. 4. The results indicate that zinc DL-methionine can attenuate the biochemical consequences of oxygen free radicals, and is comparable to other well-known antioxidants and free radical scavengers in the in vitro system that was employed.

Induction of oxidative stress by chronic administration of sodium dichromate [chromium VI] and cadmium chloride [cadmium II] to rats

Recent studies have demonstrated that both chromium (VI) and cadmium (II) induce an oxidative stress, as determined by increased hepatic lipid peroxidation, hepatic glutathione depletion, hepatic nuclear DNA damage, and excretion of urinary lipid metabolites. However, whether chronic exposure to low levels of Cr(VI) and Cd(II) will produce an oxidative stress is not shown. The effects of oral, low (0.05 LD50) doses of sodium dichromate [Cr(VI); 2.5 mg/kg/d] and cadmium chloride [Cd(II); 4.4 mg/kg/d] in water on hepatic and brain mitochondrial and microsomal lipid peroxidation, excretion of urinary lipid metabolites including malondialdehyde, formaldehyde, acetaldehyde and acetone, and hepatic nuclear DNA-single strand breaks (SSB) were examined in female Sprague-Dawley rats over a period of 120 d. The animals were treated daily using an intragastric feeding needle. Maximum increases in hepatic and brain lipid peroxidation were observed between 60 and 75 d of treatment with both cations. Following Cr(VI) administration for 75 d, maximum increases in the urinary excretion of malondialdehyde, formaldehyde, acetaldehyde, and acetone were 2.1-, 1.8-, 2.1-, and 2.1-fold, respectively, while under the same conditions involving Cd(II) administration approximately 1.8-, 1.5-, 1.9-, and 1.5-fold increases were observed, respectively, as compared to control values. Following administration of Cr(VI) and Cd(II) for 75 d, approximately 2.4- and 3.8-fold increases in hepatic nuclear DNA-SSB were observed, respectively, while approximately 1.3- and 2.0-fold increases in brain nuclear DNA-SSB were observed, respectively. The results clearly indicate that low dose chronic administration of sodium dichromate and cadmium chloride induces an oxidative stress resulting in tissue damaging effects that may contribute to the toxicity and carcinogenicity of these two cations.

TCDD endrin and lindane induced increases in lipid metabolites in maternal sera and amniotic fluids of pregnant C57BL/6J and DBA/2J mice

TCDD, endrin and lindane induce an oxidative stress and enhance lipid peroxidation in fetal and placental tissues of mice. The levels of the products resulting from altered lipid metabolism, including malondialdehyde (MDA), formaldehyde (FA), acetaldehyde (ACT) and acetone (ACON) have been determined in maternal sera and amniotic fluids of pregnant C57BL/6J and DBA/2J mice after oral administration of single fetotoxic doses of TCDD, endrin and lindane on day 12 of gestation, using high pressure liquid chromatography (HPLC). Under these conditions, TCDD given at a dose of 30 micrograms/kg body weight to C57BL/6J mice produced 2.5-3.9 and 1.7-4.0 fold increases in the levels of the four metabolites in maternal sera and the amniotic fluids, respectively. TCDD given to DBA/2J mice at a dose of 60 micrograms/kg produced 1.5-1.7 and 1.7-2.2 fold increases in the levels of these metabolites in maternal sera and the amniotic fluids, respectively. Endrin, when given at a dose of 4.5 mg/kg body weight to either mouse strain, produced increases of 1.9-3.1 and 1.7-3.2-fold in the levels of the four metabolites in maternal sera and the amniotic fluids, respectively, in the C57BL/6J mice and increases of 1.4-1.6 and 1.2-1.5 fold in the levels of these metabolites in maternal sera and the amniotic fluids, respectively, in the DBA/2J mice. Lindane given at a dose of 30 mg/kg body weight to C57BL/6J mice produced 1.5-2.0 and 1.3-1.7-fold increases in the four metabolites in maternal serum and amniotic fluids, respectively, while administration of this same dose to DBa/2J mice produced 1.2-1.5 and 1.1-1.5 fold increases, respectively. Increases in the levels of lipid metabolites occur in maternal serum and amniotic fluid as a result of enhanced lipid peroxidation in response to TCDD, endrin and lindane. Lipid peroxidation may participate in the fetotoxic effects of these xenobiotics and these effects are observed regardless of the Ah-responsiveness of the mice, although higher levels of the metabolites are produced by TCDD in Ah-responsive mice.