Cold storage sensitizes hepatocytes to oxidative stress injury

Radiology administrators nationwide were surveyed to determine current drug administration practices in their imaging departments. The survey also obtained information about the educational backgrounds of radiologic technologists administering pharmaceuticals and the documentation procedures used by imaging departments. Survey results showed that 86% of responding institutions allow radiologic technologists to administer pharmaceuticals. However, the amount and type of education technologists received regarding drug administration was limited. In addition, the type of legal documentation regarding the administration of contrast media varied considerably among the responding institutions.     

Methacrylonitrile induced oxidative stress in rat liver

MeAN administration (40mg/kg body wt/day (i.e. 1/5 of LD50) resulted in increased levels of lipid peroxidation products, conjugated dienes and lipofuscin-like substances in rat liver. Significant decrease in GSH and a decreased activity of hepatic SOD, CAT and GPx were observed. There was also an increase in glutathione S-transferase and G6PD activities, decreased plasma ceruloplasmin and vitamin C implying oxidative stress caused by MeAN.     

Adriamycin-induced oxidative stress in rat central nervous system

Adriamycin elicited a stimulation of rat central nervous system lipid peroxidation, both in vivo and in vitro, as evidenced by the increase in the content of thiobarbituric acid reactants, which was found to be NADPH-dependent. The antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase were seen to decrease on exposure to adriamycin (1 mg/kg for a period of 7 days), together with a significant decrement in the GSH/GSSG ratio, thus contributing to the oxidative insult to the tissue. The in vitro addition of GSH or vitamin E to brain homogenates offered protection against adriamycin-induced lipid peroxidation, suggesting that supplementation with these antioxidants could improve the therapeutic value of the drug.     

Effects of curcumin on P-glycoprotein in primary cultures of rat hepatocytes

Curcumin is a natural phenolic compound found in the rhizomes of Curcuma longa and endowed with beneficial biological activities including antioxidant, anticarcinogenic and hepatoprotective effects. In this study curcumin was tested for its potential ability to interact in vitro with hepatic P-glycoprotein (Pgp), in a model system represented by primary cultures of rat hepatocytes, in which spontaneous overexpression of multidrug resistance (mdr) genes occurs. In both freshly-plated hepatocytes, containing low levels of Pgp, and 72 hour-cultured hepatocytes, containing high levels of Pgp, the Rhodamine-123 (R-123) efflux, which represents a specific functional test for Pgp-mediated transport, was inhibited by curcumin in a dose-dependent manner. Western blot analysis showed that 25microM curcumin, when included in the culture medium throughout the experimental observation (72 hours), was able to significantly lower the increase of mAb C219-immunoreactive protein spontaneously occurring in the cells during culture. Curcumin, at doses ranging from 50 to 150microM was cytotoxic for freshly-plated hepatocytes, as shown by the strong decrease in the cell ability to exclude trypan blue 24 hours later, but it was significantly less cytotoxic when added to 24 or 48 hour-cultured cells. The resistance to curcumin, progressively acquired by cells during culture, was significantly reduced by high concentrations of dexamethasone (DEX) or dimethyl-sulfoxide (DMSO), culture conditions known to inhibit the spontaneous overexpression of Pgp. In addition, in a concentration-dependent manner, verapamil reverted curcumin resistance in Pgp overexpressing hepatocytes. In photoaffinity labeling studies, curcumin competed with azidopine for binding to Pgp, suggesting a direct interaction with glycoprotein. These results suggest that curcumin is able to modulate in vitro both expression and function of hepatic Pgp and support the hypothesis that curcumin, a chemopreventive phytochemical, could reveal itself also as a compound endowed with chemosensitizing properties on mdr phenotype.     

Fibrogenic effect of oxidative stress on rat hepatic stellate cells

Members of the dynamin-related proteins family have been identified in a wide range of organisms, however their precise functions remain elusive. We have identified a new member of that GTPase family in the fission yeast Schizosaccharomyces pombe. We show that Msp1+ is an essential nuclear gene encoding a 101 kDa protein whose closest homologue is the S. cerevisiae MGM1 gene product. We also report that msp1 conditional loss of function affects the maintenance of mitochondrial DNA and leads to growth arrest associated with respiratory deficiency.     

Mitochondrial oxygen radical formation during reductive and oxidative stress to intact hepatocytes

BACKGROUND: Many processes behind the admission to hospital of elderly people can lead to a deterioration in their health at the time of discharge. The aims of the study are to assess the dependency on and need for socio-health care required by elderly people aged over 64 when discharged from a hospital for acute cases, the help that patients prefer and the help that they actually receive one month following their discharge. METHODS: A total of 193 patients aged over 64 and admitted to a hospital in Valencia between February and April 1994 were studied. Information on socio-demographic characteristics, self-care capacity, mental state, main diagnosis and co-morbidity was obtained by means of an interview at the time of admission and the medical record. A multidisciplinary team evaluated the socio-health care required in each case. A second interview, one month after discharge from hospital, gathered data on the actual care received. RESULTS: At the time of admission, 17% of the patients needed partial care and 21% full care. 23% were candidates for receiving home help, 9% to be treated as out-patients and 6% in a chronic illness hospital. Most of the patients asked to live at home. One month after discharge from hospital, only 2% of patients were receiving home help, none were being treated as out-patients or in a chronic illness hospital and 3% had once again admitted to a hospital for acute cases. 8% of the patients who were living at home alone before being admitted to hospital and 5% of those who were living with someone else had gone to live with relatives. CONCLUSIONS: The reality observed reflects the lack of socio-health resources. In many cases, this situation leads families to take on the care of the elderly themselves.     

Simulation of oxidative phosphorylation in hepatocytes

Prospective relations between individual differences in both lateralised neuro-psychophysiological functions and mood ratings with immune status (CD4 and CD8 counts) were examined in asymptomatic HIV-positive men (n = 27) over thirty months. They participated in a controlled study of zidovudine versus placebo (results published elsewhere). Measures included EEG spectra, neuropsychological tests and mood ratings. A model of reciprocal lateralised influences on the immune system was tested whereby patients with left superior to right hemispheric functions were predicted to show a less deleterious outcome than those with the opposite asymmetry pattern. Prospective relations with immune status were found in the EEG with lateralised theta, alpha and beta activity; among cognitive measures with word fluency, semantic processing, and lateralised motor and recognition memory (word/face) processes; with mood ratings including depression, confusion and the total mood score. The nature of the effects supported the laterality predictions. These unique data, showing that neuro-psychophysiological factors in HIV+ but otherwise healthy subjects predict immune competence and compromise present 2-3 years later, warrant replication in a larger cohort.     

Effects of dicarboxylic acids on fatty acid-metabolizing enzymes in cultured rat hepatocytes

A clear chain-length dependent effect was observed for peroxisomal fatty acid beta-oxidation and carnitine acetyltransferase and also for mitochondrial carnitine palmitoyltransferase in primary cultures of rat hepatocytes. The extent of modulation of peroxisomal beta-oxidation was higher with even-carbon numbered dicarboxylic acids than with odd-carbon numbered ones, although such a tendency was not detected in the mitochondrial reactions. These results indicate difference in the effect of fatty acid-derived dicarboxylates on peroxisomal and mitochondrial functions.     

Chronic ethanol administration causes oxidative stress in the rat pancreas

OBJECTIVE: Reports on the histologic effects of gonadotropin-releasing hormone agonists on uterine leiomyomas provide conflicting results. Most previous studies used qualitative methods of analysis. Using quantitative and semiquantitative stereologic methods of analysis, we assessed volume density of hyalinized areas, cell density, nuclear volume, and cytoplasmic cross-sectional areas of smooth muscle cells in histologic sections and also measured diameters of collagen fibrils in electron micrographs of uterine leiomyomas. DESIGN: Thirty leiomyomas from patients treated with gonadotropin-releasing hormone agonists (10 different patient samples), age-matched control patients (10 different patient samples), and postmenopausal women (10 different patient samples) were used. Hyalinization was assessed using a microscope with a projection head and affixed morphometric grid. Cell size and density were evaluated using a video-based, computerized system attached to the microscope, for which morphometric ad hoc programs were written. Diameters of collagen fibrils were measured from electron micrographs. SETTING: The study was conducted in the Department of Pathology, Mount Sinai Medical Center, New York, NY. PATIENTS: A total of 30 patient samples were studied, with three groups comprising 10 samples each, including patients treated with gonadotropin-releasing hormone agonists, age-matched control patients, and postmenopausal women. RESULTS: Myomas from patients treated with gonadotropin-releasing hormone agonists exhibited more hyalinization, greater cell density, slightly smaller cell sizes, and larger collagen fibrils than those of age-matched control patients and postmenopausal women. CONCLUSIONS: Shrinkage after treatment with gonadotropin-releasing hormone agonists is attributed to smaller cell size and increased collagenization in myomas.     

Possible dual role of nitric oxide in oxidative stress injury: a study in perfused hepatocytes

Nitric oxide (NO) is a multifunctional messenger in many vertebrates. In the liver, NO was found to play an important but controversial role in injury produced by toxins or sepsis. The purpose of the present investigation was to further characterize the role of NO in hepatocyte oxidative injury. A cellular system formed of immobilized and perfused rat hepatocytes was used to test the ability of the latter to produce endogenous NO after lipopolysaccharide administration in vivo (LPS, 20 mg/kg i.p.) and how hepatocyte functionality competence is modified according to NO level. This cellular system also was used to delineate a relationship between exogenously delivered NO to the perfusion medium as produced by the NO donor, sodium nitroprusside (2.0 and 0.2 mM), and any alteration in the degree of injury as evoked by anoxia/reoxygenation or cumene hydroperoxide (1.0 mM and 0.2 mM). Rat hepatocytes were immobilized in low-gelling agarose and perfused with Williams E medium. Endogenous or exogenous NO was evaluated by measuring the end products of NO (NO2- + NO3-) in the perfusion medium. Functional integrity of hepatocytes was evaluated from lactate dehydrogenase (LD) leakage, urea synthesis in the perfusion medium and lipid peroxides (LP) formation. Normal, anoxia/reoxygenation or cumene hydroperoxide injured hepatocytes did not exhibit measurable NO while LPS-treated hepatocytes produced NO. Apparently, within the present experimental conditions, it seems that there was an inverse relation between the rate of NO produced after LPS administration and the rate of lipid peroxides formed in the hepatocytes. Low concentration of sodium nitroprusside (as NO donor) significantly decreased LD leakage, increased the rate of urea synthesis and increased trypan blue exclusion by hepatocytes in anoxia/reoxygenation or cumene hydroperoxide injured (0.2 mM) cells. Lipid peroxides were decreased by NO in cumene hydroperoxide injured hepatocytes. The present data suggest that NO endogenously produced, or exogenously delivered, has an ameliorative role in mild oxidative liver injury models, but not in severe cases and that inside hepatocytes, there is a very delicate balance between the rate of NO production and its consumption. The disturbance in this balance may be responsible for injury due to the formation of more toxic oxygen species.     

Effects of oxidative stress on prion protein expression in PC12 cells

PC12 cells are known to express the prion protein, a normal cell surface glycoprotein. This protein is upregulated in PC12 cells differentiated with nerve growth factor. A neurotoxic prion protein peptide, PrP106-126, is not toxic to PC12 cells alone. PrP106-126 is toxic to PC12 cells co-cultured with microglia and more so to NGF-differentiated PC12 cells. PC12 cells selected for resistance to either copper toxicity or oxidative stress have higher levels of PrP(C) expression. Both PC12 variants are more sensitive to the toxicity of PrP106-126. This suggests that PC12 sensitivity to PrP106-126 toxicity is related to prion protein expression and not to a state of high differentiation induced by NGF. Variants of PC12 cells that are more resistant to copper toxicity have higher levels of anti-oxidant enzymes, superoxide dismutase and glutathione peroxidase. Our results suggest that cells expressing higher levels of PrP(C) have higher resistance to oxidative stress or copper toxicity but are more sensitive to PrP106-126 toxicity. Prion protein expression may be involved in both the metabolism of copper and resistance to oxidative stress. Increased cellular resistance to copper toxicity may be partly related to increased activity of anti-oxidant enzymes.     

Effects of exercise-induced oxidative stress on nitric oxide release and antioxidant activity

This study shows that acute exercise in healthy subjects is a modest oxidative stress, which may be related to an increase in antioxidant activity and down-regulation of nitric oxide formation.     

Increased oxidative stress in rat liver and pancreas during progression of streptozotocin-induced diabetes

1. Oxygen free radicals have been suggested to be a contributory factor in complications of diabetes mellitus. There are many reports indicating the changes in parameters of oxidative stress in diabetes mellitus. In this study we aimed to identify whether oxidative stress occurs in the liver and pancreas in the initial stages of development of diabetes. 2. We therefore investigated the lipid peroxide level (thiobarbituric acid-reactive substances, TBARS) and activities of antioxidant enzymes [superoxide dismutase (SOD), catalase and glutathione peroxidase] in liver and pancreas of control and streptozotocin-induced diabetic rats at various stages of development of diabetes. 3. Male Sprague-Dawley rats were divided into two groups: group I, control (n = 42) and group II, diabetic (n = 42). Each group was further subdivided into seven groups consisting of six rats each. Rats in these subgroups were studied at weekly intervals (0 to 6 weeks). Plasma glucose levels, TBARS levels and activities of antioxidant enzymes were measured in liver and pancreas at various time intervals. 4. There was a significant (P < 0.05) and progressive increase in TBARS levels of liver and pancreas in the diabetic group. Total SOD and Cu-Zn-SOD activity increased (P < 0.05) with progression of diabetes while Mn-SOD activity showed no significant change in either tissue. Catalase and glutathione peroxidase activities increased significantly (P < 0.05) in liver and pancreas. 5. Immunohistochemical study of pancreatic islet revealed a decrease in the expression of insulin with progression of diabetes. However, glucagon and somatostatin showed an increase in immunoreactivity and a difference in their distribution pattern. 6. The findings of the present study suggest that oxidative stress starts at early onset of diabetes mellitus and increases progressively. In conclusion, the structural damage to these tissues or complications of diabetes mellitus may be due to oxidative stress.     

Effects of tumor necrosis factor-alpha on glucose and albumin production in primary cultures of rat hepatocytes

Tumor necrosis factor-alpha (TNF) is known to alter significantly in vivo hepatic glucose and albumin metabolism. However, it remains unclear whether the observed effects represent direct actions of this factor or secondary responses due to the recruitment of other mediator systems. The present study was designed to investigate direct actions of TNF on glucose and albumin production in primary cultures of rat hepatocytes. Addition of TNF to the culture medium resulted in a 45% to 50% reduction in glucose production from a control level of 239 +/- 15 nmol/plate.h. This effect was reversed by addition of anti-TNF monoclonal antibody. In glycogen-depleted cells, short-term (5-hour) incubation with TNF did not affect hepatocyte albumin secretion, which was 8.13 +/- 0.29 microgram/plate.h. However, in cells exposed to insulin or in non-glycogen-depleted cells, addition of TNF resulted in a 10% to 25% reduction in albumin production. These findings indicate that TNF exerts direct inhibitory effects on hepatocyte glucose and albumin production, but the effects on the latter process are modest. A notable aspect of the findings is that the albumin effects are insulin or glucose substrate-dependent, which may have implications regarding liver function during nutritional support in critical illness.     

Effects of D-mannoheptulose and its hexaacetate ester upon D-glucose metabolism in rat hepatocytes

D-mannoheptulose, which inhibits hexokinase isoenzymes in a predominantly competitive manner, has been found to decrease much more modestly D-glucose metabolism in pancreatic islets exposed to a low, as distinct from high, concentration of the hexose. In the present study, which aimed at investigating the factor(s) possibly responsible for such a phenomenon, a comparable situation was found to prevail in rat hepatocytes. However, when the hexaacetate ester of D-mannoheptulose was used instead of the unesterified heptose, the relative extent of inhibition of D-[5-3H]glucose utilization and D-[U-14C]glucose conversion to 14C-labelled acidic metabolites was comparable in hepatocytes exposed to either 1.7 or 8.3 mM D-glucose. Moreover, at the low D-glucose level, the incorporation of 3-O-methyl-D-glucose (6.6 mM) into the incubation medium increased the inhibitory action of unesterified D-mannoheptulose upon D-glucose metabolism. These findings suggest that an insufficient uptake of the heptose accounts, in part at least, for its poor efficiency as inhibitor of D-glucose catabolism in liver, and presumably islet cells exposed to low concentrations of the hexose.     

Endurance training improves the resistance of rat diaphragm to exercise-induced oxidative stress

The current study was designed to test the hypothesis that endurance training improves the ability of the diaphragm muscle to resist exercise-induced oxidative stress. Twenty-eight male Wistar rats were assigned to either untrained or trained groups. Trained rats were treadmill-trained for 9 wk. Each group was subdivided into acutely exercised or nonexercised groups. Diaphragm muscle from each rat was analyzed to determine the levels of certain antioxidant enzymes: Mn-superoxide dismutase (Mn-SOD), Cu,Zn-superoxide dismutase (Cu,Zn-SOD), glutathione peroxidase, and catalase. In addition, interleukin-1 and myeloperoxidase levels were determined. Endurance training upregulated all of the antioxidant enzymes. Conversely, acute exercise increased glutathione peroxidase and catalase in untrained rats, while it had no overt effect on any antioxidant enzymes in trained rats. Both Mn-SOD and Cu,Zn-SOD contents and activities were increased with endurance training. However, the mRNA expressions of both forms of SOD did not show any significant change with endurance training. Acute exercise also increased the levels of interleukin-1 and myeloperoxidase in untrained rats but not in trained rats. Moreover, acute exercise significantly increased the ability of neutrophils to produce superoxide, especially in untrained rats. The results from this study demonstrate that endurance training can upregulate certain antioxidant enzyme activities in rat diaphragm muscle, indicating the potential for improvement of the resistance to intracellular reactive oxygen species. The results of this study also suggest that acute exercise may cause oxidative damage in rat diaphragm through the activation of the inflammatory pathway and that endurance training may minimize such an extracellular oxidative stress by acute exercise.     

Effects of vitamin E and C supplementation on oxidative stress and viral load in HIV-infected subjects

OBJECTIVES: The HIV-infected population is known to be oxidatively stressed and deficient in antioxidant micronutrients. Since in vitro replication of HIV is increased with oxidative stress, this study assessed the effect of antioxidant vitamin supplementation on lipid peroxidation, a measure of oxidative stress, and viral load in humans. DESIGN: A randomized placebo-controlled, double-blind study. METHODS: Forty-nine HIV-positive patients were randomized to receive supplements of both DL-alpha-tocopherol acetate (800 IU daily) and vitamin C (1000 mg daily), or matched placebo, for 3 months. Plasma antioxidant micronutrient status, breath pentane output, plasma lipid peroxides, malondialdehyde and viral load were measured at baseline and at 3 months. New or recurrent infections for the 6-month period after study entry were also recorded. RESULTS: The vitamin group (n = 26) had an increase in plasma concentrations of alpha-tocopherol (P < 0.0005) and vitamin C (P < 0.005) and a reduction in lipid peroxidation measured by breath pentane (P < 0.025), plasma lipid peroxides (P < 0.01) and malondialdehyde (P < 0.0005) when compared with controls (n = 23). There was also a trend towards a reduction in viral load (mean +/- SD changes over 3 months, -0.45 +/- 0.39 versus +0.50 +/- 0.40 log10 copies/ml; P = 0.1; 95% confidence interval, -0.21 to -2.14). The number of infections reported was nine in the vitamin group and seven in the placebo group. CONCLUSION: Supplements of vitamin E and C reduce oxidative stress in HIV and produce a trend towards a reduction in viral load. This is worthy of larger clinical trials, especially in HIV-infected persons who cannot afford new combination therapies.     

Indicators of oxidative stress in aging rat brain. The effect of nerve growth factor

INTRODUCTION AND OBJECTIVE: Increased oxidative stress during ageing and the neurodegenerative disorders associated with this has been described. The central nervous system is particularly vulnerable to oxidative damage because of its high energy requirements, high oxygen consumption, high tissue concentration of iron and relatively low levels of some antioxidant systems. Treatment with neurotrophic factors may reverse neurone deterioration and stimulate cholinergic activity in aged rats. It may have a similar neuroprotector effect against damage due to ischaemic reperfusion, hypoglycaemia, inflammation and other pathological conditions involving oxidative stress. In this study we determined some indicators of oxidative stress in rat brains during ageing and evaluated this in response to a plan of treatment with murine nerve growth factor (FCN) for 38 days. MATERIAL AND METHODS: Biochemical techniques were used for determination of oxidative stress indicators. RESULTS AND CONCLUSIONS: We found that with age there was a significant increase in phospholipase A2 and superoxide dysmutase activity and concentration of hipoperoxidases, whilst the concentration of reduced glutathion fell. Catalase activity increased in the hippocampal and striate regions and decreased in the cortex and septal area. There was less oxidative stress in rats treated with FCN. In view of our results, we conclude that the level of oxidative stress increases with ageing, with significant differences between areas of the brain. The region most vulnerable to damage from species reactive to oxygen was the hippocampus, and the protective effect of FCN may be related to potentiation of antioxidant defenses.