Free Radical Metabolism Research Articles

Quantitative assessment of gene expression following acute spinal cord injury

A unique gene expression pattern/transcriptome characterizes the presentation of every disease state. Strategies for identification of gene families with altered expression patterns offer an information rich approach to initially assess the relevance of gene expression to disease pathology. To identify important candidate genes critical to the biochemical mechanisms mediating spinal cord injury (SCI), we have selected gene families that may have a relevant impact on SCI for analysis by real time PCR. Using this quantitative, fluorescence‐based method for the real time detection of PCR, we have evaluated the expression of 80 known genes at time points up to 24 h post SCI. These families/groups include the TGF‐β ligand, receptor and Smad superfamily; matrix metalloproteinases; and genes involved in angiogenesis and wound healing; free radical metabolism; cell death; as well as miscellaneous growth and regulatory factors. The gene expression patterns were evaluated in samples from 12 and 24 h post injury or sham controls using a rat contusion model. 36 genes had a two or greater cycle number difference between at least one injury time point and control. 10 genes exhibiting the largest change with a four or greater cycle number difference compared to controls were also analyzed at 2 and 6 h post injury. Additional real time PCR studies were performed on 4 of these 10 genes at all time points directly relating changes in cycle number with fold induction. The ability to rapidly and directly quantitate gene expression has provided a powerful approach to elucidate genes potentially relevant to cellular events in SCI.

Hypothalamic Digoxin, Hemispheric Dominance and the Acquired Immunodeficiency Syndrome

Objectives: Hypothalamic digoxin, an isoprenoidal metabolite, is an endogenous regulator of membrane Na⁺-K⁺ ATPase activity, immune activation and synaptic neurotransmission. The objective of this study was to assess the role of hypothalamic digoxin and hemispheric dominance in the pathogenesis of the acquired immunodeficiency syndrome (AIDS) and in the genesis of sexual orientation. Methods: The isoprenoid-pathway-related cascade – (i) isoprenoidal metabolites – digoxin, dolichol and ubiquinone, (ii) tryptophan/tyrosine catabolic patterns, (iii) glycoconjugate metabolism, (iv) free radical metabolism and (v) membrane composition were assessed in AIDS (CDC stage – group IV – subgroup C), individuals with differing hemispheric dominance as well as in individuals with differing sexual orientation. Statistical analysis was done by Student’s t test with modified degrees of freedom. Results: The HMG CoA reductase activity was increased with increased digoxin and dolichol levels and reduced ubiquinone levels in AIDS. The membrane Na⁺-K⁺ ATPase activity and serum magnesium levels were reduced. The tryptophan catabolites (serotonin, quinolinic acid, nicotine and strychnine) were increased and the tyrosine catabolites (morphine, dopamine and noradrenaline) were reduced. The serum glycoconjugate metabolites were increased and lysosomal stability was reduced in AIDS. There was reduced incorporation of glycoconjugates into membranes and an increased membrane cholesterol:phospholipid ratio. Lipid peroxidation products and NO were increased while free radical scavenging enzymes and reduced glutathione were reduced. The biochemical patterns obtained in AIDS correlated with those obtained in right-hemispheric dominance and homosexuals/bisexual states. Conclusions: Hypothalamic digoxin and right-hemispheric dominance is important in the predisposition to AIDS as well as homosexual/bisexual states.

Polymorphism in alcohol-metabolizing enzymes, glutathione S-transferases and apolipoprotein E and susceptibility to alcohol-induced cirrhosis and chronic pancreatitis.

Susceptibility to organ damage induced by alcohol may be due to inherited variation (polymorphism) in ethanol-metabolizing enzymes, or to polymorphisms affecting free radical or lipid metabolism mediated by enzymes such as glutathione S-transferases and apolipoprotein E. The aim was to compare the genotype frequencies of alcohol dehydrogenase-2 (ADH2), ADH3, aldehyde dehydrogenase-2 (ALDH2), cytochrome P450-2E1 (CYP2E1), glutathione S-transferase-M1 (GSTM1), GSTT1, and apolipoprotein E in patients with alcoholic cirrhosis and alcoholic chronic pancreatitis to those in control groups. The case-control study was restricted to Caucasian adults: 57 with alcoholic cirrhosis, 71 with alcoholic chronic pancreatitis, 57 alcoholics without apparent organ damage and 200 healthy blood donors. Genotypes were determined by restriction fragment length polymorphism after amplification of genomic DNA by polymerase chain reaction. The genotype ADH3*2/*2 was more frequent in patients with cirrhosis (40%) than blood donors (12%; OR 4.92, 95% CI 2.36-10.31) and patients with chronic pancreatitis (8%; OR 7.33, 95% CI 2.54-23.78) but was not significantly different from alcoholic controls (23%; OR 2.27, 95% CI 0.95-5.66). Patients with cirrhosis also had a higher frequency (P < 0.05) of ADH2*1/*1 (100%) than blood donors (92%) and those with chronic pancreatitis (93%). The frequencies of genotypes of ALDH2, CYP2E1, GSTM1, GSTT1 and apolipoprotein E were similar in all groups. Alcoholic cirrhosis but not alcoholic chronic pancreatitis is associated with ADH3*2/*2 and perhaps with ADH2*1/*1. Both genes encode less active alcohol-metabolizing enzymes that may be associated with cirrhosis because of delayed formation of acetaldehyde (with higher intakes of alcohol), or diversion of alcohol metabolism through pathways other than ADH.

HYPOTHALAMIC DIGOXIN, HEMISPHERIC CHEMICAL DOMINANCE, AND ENDOCRINE/METABOLIC/CELLULAR REGULATION

The hypothalamus produces an endogenous membrane Na+-K+ ATPase inhibitor and regulator of neurotransmission, digoxin. Digoxin, a steroidal glycoside, is synthesized by the isoprenoid pathway. In view of the reports of elevated digoxin levels in metabolic syndrome X with high body mass index, the isoprenoid-mediated pathway biochemical cascade was assessed in individuals with high and low body mass index. It was also assessed in individuals with differing hemispheric dominance to find out the relationship among digoxin status, body mass index, and hemispheric dominance. The isoprenoid pathway metabolites, tryptophan/tyrosine catabolic patterns, glycoconjugate, and free radical metabolism, as well as membrane composition, were assessed. In individuals with high body mass index, an upregulated isoprenoid pathway with increased digoxin levels, increased glycoconjugates, and dolichol levels, reduced lysosomal stability, low ubiquinone levels with increased free radical generation, and increased membrane cholesterol:phospholipid ratio were observed. The reverse patterns were seen in individuals with a low body mass index. The patterns in individuals with a high body mass index and low body mass index correlated with right hemispheric dominance and left hemispheric dominance, respectively. Hemispheric dominance and digoxin status regulated the differential metabolic pattern observed in individuals with high and low body mass index. Hypothalamic digoxin/cerebral dominance can regulate the metabolic/endocrine function, as well as the structure/function of cellular organalle.

HYPOTHALAMIC DIGOXIN, CEREBRAL DOMINANCE, AND MITOCHONDRIAL FUNCTION/FREE RADICAL METABOLISM

The present study assessed the biochemical differences of free radical metabolism and mitochondrial function between right hemispheric dominant and left hemispheric dominant individuals. The following parameters were measured: (1) plasma HMG CoA reductase activity, (2) isoprenoid metabolites--digoxin and ubiquinone, (3) plasma magnesium and RBC membrane Na+-K+ ATPase activity, (4) lipid peroxidation products--malondialdehyde, hydroperoxides and conjugated dienes, and NO, (5) reduced glutathione, and (6) activity of superoxide dismutase, catalase, GSH peroxidase, and GSH reductase. The results showed that right hemispheric dominant individuals had (i) increased plasma HMG CoA reductase activity and elevated digoxin levels, (ii) decreased plasma magnesium and RBC membrane Na+-K+ ATPase activity, (iii) reduced ubiquinone levels, (iv) with increased levels of lipid peroxidation products and NO, (v) decreased levels of reduced glutathione and free radical scavenging enzymes, and (vi) increased tryptophan and reduced tyrosine levels. Left hemispheric dominant individuals had the opposite patterns. Right hemispheric dominance represents a hyperdigoxinemic state with membrane sodium-potassium ATPase inhibition and increased lipid peroxidation. Left hemispheric dominance represents the reverse pattern with hypodigoxinemic/membrane sodium-potassium ATPase stimulation and decreased lipid peroxidation. Cerebral dominance can regulate mitochondrial function and free radical metabolism.

Hypothalamic digoxin-mediated model for subacute sclerosing panencephalitis.

The isoprenoid pathway including endogenous digoxin was assessed in subacute sclerosing panencephalitis (SSPE). This was also studied for comparison in patients with right hemispheric and left hemispheric dominance. The following parameters were measured in patients with SSPE and in individuals with right hemispheric, left hemispheric and bihemispheric dominance-(a) plasma HMG CoA reductase, digoxin, dolichol, ubiquinone, and magnesium levels; (b) tryptophan/tyrosine catabolic patterns; (c) free-radical metabolism; (d) glycoconjugate metabolism; and (e) membrane composition and RBC membrane Na(+)-K(+) ATPase activity. The isoprenoid pathway was upregulated with increased digoxin synthesis in patients with SSPE and in those with right hemispheric dominance. In this group of patients: (a) the tryptophan catabolites were increased and the tyrosine catabolites reduced; (b) the dolichol and glycoconjugate levels were elevated; (c) lysosomal stability was reduced; (d) ubiquinone levels were low and free-radical levels increased; and (e) the membrane cholesterol:phospholipid ratios were increased and membrane glycoconjugates reduced. On the other hand, in patients with left hemispheric dominance the reverse patterns were obtained. The upregulated isoprenoid pathway and hypothalamic digoxin are involved in the pathogenesis of SSPE. SSPE occurs in right hemispheric chemically dominant individuals and a pathogenetic model for SSPE implicating hypothalamic digoxin is proposed.

Toxicity by pyruvate in HepG2 cells depleted of glutathione: role of mitochondria

Several studies have shown that pyruvate can scavenge H 2O 2 and protect from H 2O 2-mediated cell injury. Mitochondria are critical participants in the control of apoptotic and necrotic cell death. Mitochondrial GSH plays an important role in the maintenance of cell functions and viability by metabolism of oxygen free radicals generated by the respiratory chain. Since loss of GSH, especially mitochondrial GSH, is associated with increased production of reactive oxygen species and cell toxicity, the ability of pyruvate to protect against these actions was evaluated. Adding pyruvate to HepG2 cells depleted of GSH by treatment with l-buthionine sulfoximine (BSO) surprisingly caused loss of viability after 24 and 48 h of incubation. Anoxia, treatment with antioxidants, and infection with cytosolic catalase, and interestingly, catalase expressed in the mitochondrial compartment were able to rescue the HepG2 cells from this pyruvate plus BSO injury, suggesting a key role for H 2O 2, and lipid peroxides as mediators in the cytotoxicity. This toxicity and cell death observed was linked to damage to the mitochondria as evidenced by the increased lipid peroxidation in total homogenate and mitochondrial fraction, loss of mitochondrial membrane potential, and a decrease in protein-sulfhydryl groups. The type of cell death observed under these conditions was a mixture of apoptosis and necrosis. These results suggest that the protective ability of pyruvate against oxidant damage requires a functional GSH pool, especially in the mitochondrial compartment, and that in the absence of GSH, pyruvate increases cell injury by damaging the mitochondria, presumably as a consequence of enhanced electron flow and reactive oxygen production by the respiratory chain.

Oxidative stress in Rett syndrome

The investigation of parameters that might influence the neurological evolution of Rett syndrome might also yield new information about its pathogenic mechanisms. Oxidative stress caused by oxygen free radicals is involved in the neuropathology of several neurodegenerative disorders, as well as in stroke and seizures. To evaluate the free radical metabolism in Rett syndrome, we measured red blood cell antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase, glutathione reductase and catalase) and plasma malondialdehyde, as lipid peroxidation marker in a group of patients with Rett syndrome. No significant differences were observed in erythrocyte glutathione peroxidase, glutathione reductase and catalase activities, between the Rett syndrome patients and the control group. Erythrocyte superoxide dismutase activities were significantly decreased in Rett syndrome patients ( P<0.001) compared with the control group. Plasma malondialdehyde concentrations were significantly increased in Rett syndrome patients ( P<0.001). An unbalanced nutritional status in Rett syndrome might explain the reduced enzyme activity found in these patients. Our results suggest that free radicals generated from oxidation reactions might contribute to the pathogenesis of Rett syndrome. The high levels of malondialdehyde reflect peroxidative damage of biomembranes that may contribute to progressive dementia, impaired motor function, behavioural changes, and seizures, in Rett syndrome. We found a probable relationship between the degree of oxidative stress and the severity of symptoms, which should be further investigated with a larger number of patients in different disease stages.

Interactions of oxidative stress with thiamine homeostasis promote neurodegeneration

Thiamine-dependent processes are diminished in brains of patients with several neurodegenerative diseases. The decline in thiamine-dependent enzymes can be readily linked to the symptoms and pathology of the disorders. Why the reductions in thiamine linked processes occur is an important experimental and clinical question. Oxidative stress (i.e. abnormal metabolism of free radicals) accompanies neurodegeneration and causes abnormalities in thiamine-dependent processes. The vulnerability of thiamine homeostasis to oxidative stress may explain deficits in thiamine homeostasis in numerous neurological disorders. The interactions of thiamine with oxidative processes may be part of a spiral of events that lead to neurodegeneration, because reductions in thiamine and thiamine-dependent processes promote neurodegeneration and cause oxidative stress. The reversal of the effects of thiamine deficiency by antioxidants, and amelioration of other forms of oxidative stress by thiamine, suggest that thiamine may act as a site-directed antioxidant. The data indicate that the interactions of thiamine-dependent processes with oxidative stress are critical in neurodegenerative processes.

Microdialytical monitoring of uric and ascorbic acids in the brains of patients after severe brain injury and during neurovascular surgery

OBJECTIVESMicrodialysis has been extensively used to monitor brain metabolism in the extracellular fluid of patients with severe head injury, to detect the onset of secondary ischaemic damage. The aim was...

The relationships between plasma and erythrocyte antioxidant enzymes and lipid peroxidation in patients with rheumatoid arthritis

Objective. The present study was undertaken to evaluate the activities of some key erythrocyte and plasma enzymes participating in free radical metabolism and the end product of lipid peroxidation in rheumatoid arthritis, and whether there are any differences for these parameters between newly diagnosed untreated patients and rheumatoid arthritis patients on drug therapy. Patients and methods. Superoxide dismutase and catalase activities, and malondialdehyde levels were determined in erythrocytes and plasma samples from 54 patients with rheumatoid arthritis (21 of whom without any treatment and 33 on classical therapy regimens) and from 33 healthy controls. Results. There were no statistically significant differences in mean values of activities of the erythrocyte enzymes between the patients and controls. Malondialdehyde levels were significantly increased in both newly diagnosed untreated patients and patients on drug therapy compared to control subjects. Malondialdehyde levels were lower in the treated group than the newly diagnosed untreated group (0.214 ± 0.111 μmol/L and 0.388 ± 0.075 μmol/L, respectively) ( P < 0.0001). Mean plasma superoxide dismutase activity was lower in the group of newly diagnosed untreated patients compared to those of the treated and control groups (1.31 ± 0.69 U/mL, 1.79 ± 0.94 U/mL and 2.48 ± 0.95 U/mL, respectively) ( P < 0.0001, untreated vs control groups). Conclusions. These results suggest sufficient antioxidant enzyme activities in erythrocytes in patients with rheumatoid arthritis and also increased lipid peroxidation end products in newly diagnosed untreated patients compared to control group and patients on drug therapy.

Mechanisms of cytokine-induced death of cultured bovine luteal cells

Tumour necrosis factor alpha (TNF-alpha) and gamma-interferon (IFN-gamma) are cytotoxic to bovine luteal cells in vitro and may contribute to cell death during luteolysis in vivo. In this study, the mechanism by which luteal cells are killed by TNF-alpha and IFN-gamma was investigated. Luteal cells were cultured for 7 days in the presence or absence of TNF-alpha and IFN-gamma. Inhibitors of arachidonate metabolism or scavengers of free radicals were included in the culture media. In addition, the effect of IFN-beta on the viability of cytokine-treated luteal cells was tested. Lastly, untreated and cytokine-treated cells were subjected to single cell gel electrophoresis for quantification of DNA fragmentation. Neither indomethacin nor nordihydroguaiaretic acid, which are inhibitors of cyclooxygenase and lipoxygenase, respectively, were able to prevent cytokine-induced cell death. Similarly, both the phospholipase A(2) inhibitor arachidonyltrifluoromethyl ketone and the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, were largely without effect. In contrast, while vitamin C did not significantly affect viability, superoxide dismutase plus catalase increased viability of cytokine-treated cells (P < 0.05), and IFN-beta prevented cell death (P < 0.05). Finally, while control cells remained free of DNA damage, TNF-alpha plus IFN-gamma induced significant amounts of DNA damage by 48 h after initiation of treatment (P < 0.05). In conclusion, reactive oxygen species, but not arachidonate metabolism or nitric oxide, contribute to cytokine-induced luteal cell death in vitro, and the process of cell death may be via apoptosis. Furthermore, IFN-beta may confer protective effects against cytokine-induced cell death in bovine luteal cells.

Mechanisms of cytokine-induced death of cultured bovine luteal cells

Tumour necrosis factor alpha (TNF-alpha) and gamma-interferon (IFN-gamma) are cytotoxic to bovine luteal cells in vitro and may contribute to cell death during luteolysis in vivo. In this study, the mechanism by which luteal cells are killed by TNF-alpha and IFN-gamma was investigated. Luteal cells were cultured for 7 days in the presence or absence of TNF-alpha and IFN-gamma. Inhibitors of arachidonate metabolism or scavengers of free radicals were included in the culture media. In addition, the effect of IFN-beta on the viability of cytokine-treated luteal cells was tested. Lastly, untreated and cytokine-treated cells were subjected to single cell gel electrophoresis for quantification of DNA fragmentation. Neither indomethacin nor nordihydroguaiaretic acid, which are inhibitors of cyclooxygenase and lipoxygenase, respectively, were able to prevent cytokine-induced cell death. Similarly, both the phospholipase A(2) inhibitor arachidonyltrifluoromethyl ketone and the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine, were largely without effect. In contrast, while vitamin C did not significantly affect viability, superoxide dismutase plus catalase increased viability of cytokine-treated cells (P < 0.05), and IFN-beta prevented cell death (P < 0.05). Finally, while control cells remained free of DNA damage, TNF-alpha plus IFN-gamma induced significant amounts of DNA damage by 48 h after initiation of treatment (P < 0.05). In conclusion, reactive oxygen species, but not arachidonate metabolism or nitric oxide, contribute to cytokine-induced luteal cell death in vitro, and the process of cell death may be via apoptosis. Furthermore, IFN-beta may confer protective effects against cytokine-induced cell death in bovine luteal cells.

Effect of L-Carnitine Supplementation in Hemodialysis Patients

Background/Aim:L-Carnitine is important in β-oxidation of fatty acids. A lack of carnitine in hemodialysis patients is caused by insufficient carnitine synthesis and especially by its loss during dialysis. The aim of our study was to test the influence of carnitine supplementation on plasma lipids, red blood cell count, and metabolism of free radicals. Methods: Twelve regularly dialyzed patients (average age 55.5 years, average dialysis treatment period 22.5 months) were given 15 mg/kg L-carnitine intravenously three times weekly (after each hemodialysis session) for 6 months. Laboratory markers of oxidative stress, lipid metabolism, and red blood cell count were measured before the supplementation and then controlled during two 3-month intervals. Nine patients were retested 3 months after the supplementation had ended. Results: All supplemented patients showed increased plasma free carnitine in comparison with the pretreatment values (113.3 ± 11.2 vs. 62.3 ± 16.7 µmol/l, p < 0.001). The proportion of decreased L-carnitine values after hemodialysis was reduced from 79 to 22%. Plasma total cholesterol (4.66 ± 0.30 mmol/l after treatment vs. 5.65 ± 1.53 mmol/l before treatment, p < 0.05) and LDL cholesterol (1.74 ± 0.86 vs. 2.81 ± 1.43 mmol/l, p < 0.05) decreased. The albumin concentration significantly increased from 34.8 ± 7.3 to 46.0 ±5.4 g/l (p < 0.05). Intraerythrocyte reduced glutathione increased from 1.65 ± 0.25 to 2.23 ± 0.16 mmol/l (p < 0.001), and the plasma antioxidant capacity increased from 1.65 ± 0.09 to 2.06 ± 0.17 mmol/l (p < 0.001). At the same time, plasma malondialdehyde decreased from 4.18 ± 0.72 to 3.07 ± 0.35 µmol/l (p < 0.001). The erythropoietin dose could be reduced from an average value of 5,500 to 3,500 U/week. No significant changes in the above-mentioned parameters were observed in a control group of dialyzed patients without L-carnitine supplementation. Conclusion: Regular carnitine supplementation of hemodialysis patients can improve their lipid metabolism, protein nutrition, red blood cell count, and antioxidant status.

In Vivo EPR Imaging of the Distribution and Metabolism of Nitroxide Radicals in Human Skin

While altered cellular free radical and redox metabolism are critical factors in many human diseases, it has not been previously possible to both measure and image these processes in humans. The development and application of electron paramagnetic resonance instrumentation capable of in vivo spectroscopy and imaging of free radicals in human skin are reported. The instrumentation uses a specially designed topical resonator and a 2.2-GHz microwave bridge. Noninvasive measurements of the distribution and metabolism of the topically applied nitroxide, (15)N-perdeuterated tempone (100 mM), in forearm skin were performed. A single broad peak due to the concentrated label at the skin surface was initially observed, followed by a sharp doublet from the diluted label that permeated the skin. The penetration of the label into the skin and its metabolic clearance were modeled using kinetic equations. It was observed that the penetration process from the skin surface into the dermis and subcutaneous regions, as well as its clearance from these regions, could be described by single exponential functions. Phantom imaging experiments using the nitroxide showed that a spatial resolution of up to 50 microm could be achieved. The skin imaging measurements showed two bands in the distribution of the label along the skin depth. The first band appeared in the outer 400 microm of the skin, the epidermis region, whereas the second band was centered at a depth of 1000 microm in the subcutaneous region with a thickness about 400 microm. These two bands decayed and merged into a single band with time. The results are important in the understanding of the permeability and metabolism of free radicals in human skin.

Radiation induced oxidative stress: II studies in liver as a distant organ of tumor bearing mice.

Since the radiation dose tolerance of normal tissues/organs away from the site of tumor influences the success of radiation therapy of cancer, and antioxidant status is likely to be one of the factors to determine the tolerance; the radioresponse of antioxidant enzymes has been examined in the liver as a representative distant organ in the tumor-bearing mice. Swiss albino male mice (7-8 weeks old) with Ehrlich solid tumor in the thigh pad were irradiated with different doses of gamma-radiation (0-9 Gy) at a dose rate of 0.0153 Gy/s and the specific activities of enzymes involved in the free radical metabolism were determined in the liver. Except GST, the activities of SOD, DTD and Gly I as well as the GSH content were found to be higher in the liver of tumor-bearing mice compared to the non-tumor bearing mice. The catalase activity progressively decreased with dose in both the groups of mice. However, the activity was relatively higher in the liver of tumor- bearing mice than the control. Thus, the radioresponse of antioxidant enzymes seemed to be significantly different in the liver of tumor-burdened mice compared to controls. The enhanced activities might be due to relatively more damage caused by radiation. The higher levels of NO* and peroxidative damage in the liver of tumor-bearing mice probably suggest this possibility. These findings of the present work might have some serious implications as the increased radiation-damage of the distant normal organs (due to tumor burden) is likely to adversely affect the therapeutic gain.

Influence of hyper- and hypothyroidism on lipid peroxidation, unsaturation of phospholipids, glutathione system and oxidative damage to nuclear and mitochondrial DNA in mice skeletal muscle.

While the biochemical literature on free radical metabolism is extensive, there is little information on the endocrine control of tissue oxidative stress, and in the case of thyroid hormones it is mainly limited to liver tissue and to short-term effects on a few selected biochemical parameters. In this investigation, chronic hypothyroidism and hyperthyroidism were successfully induced in mice, and various oxidative-stress-related parameters were studied in skeletal muscle. In vivo and in vitro lipid peroxidation significantly increased in hyperthyroidism and did not change in the hypothyroid state. The fatty acid composition of the major phospholipid classes was affected by thyroid hormones, leading to a significant decrease in total fatty acid unsaturation both in hypothyroid and hyperthyroid muscle in phosphatidylcholine and phosphatidylethanolamine fractions. In cardiolipin, however, the double bond content significantly increased as a function of thyroid status, leading to a 2.7 fold increase in the peroxidizability index from euthyroid to hyperthyroid muscle. Cardiolipin content was also directly and significantly related to thyroid state across the three groups. Glutathione system was not modified by thyroid state. The oxidative damage marker 8-oxo-7,8-dihydro-2'-deoxyguanosine did not change in mitochondrial DNA, and decreased in genomic DNA both in hypothyroid and hyperthyroid muscle. The results indicate that chronic alterations in thyroid status specially affect oxidative damage to lipids in skeletal muscle, with a probably stronger effect on mitochondrial membranes, whereas the cytosolic redox potential and DNA are better protected possibly due to homeostatic compensatory reactions on the long-term.

What is the source of free radicals causing hemolysis in stored blood ?

The quality of stored blood can be deteriorated by hemolysis caused by free radicals. The purpose of this study was to elucidate whether neutrophile leukocytes are the source of free radicals in stored blood as in hemodialyzed patients. Resuspensions with low (LL) or high (HL) leukocyte concentrations were prepared from samples of twenty healthy volunteers. The samples were incubated for 10 days at 4 °C and then for one day at 37 °C. Markers of hemolysis and free radical metabolism were examined before and after incubation in LL and HL samples. In spite of the difference of leukocytes counts in LL and HL resuspensions (p&lt;0.0001), the pre-incubation values of all laboratory parameters were practically identical. In post-storage samples, superoxide dismutase and glutathione peroxidase activities did not differ in either group. Reduced glutathione in erythrocytes and extracellular antioxidant capacity were insignificantly lower in HL resuspensions, but the increase of malondialdehyde was much more pronounced in the HL samples (p&lt;0.0001). The degree of hemolysis, expressed as the extracellular increase of potassium (p&lt;0.001), hemoglobin (p&lt;0.05) and lactate dehydrogenase (p&lt;0.05), was higher in the HL samples. Our results support the hypothesis that leukocytes participate in free radical production in stored blood.

Does exogenous melatonin influence the metabolism of free radicals and pain sensation in the rat?

Melatonin has been shown to play a role in antioxidative defence. We therefore studied its effect on oxidative damage to the rat cerebral cortex evoked by painful stimulation and immobilization-induced stress. Moreover, the effect of melatonin on chronic pain perception was examined. Rats were injected with either a high dose of melatonin (100 mg/kg i.p.) or a vehicle for five days and were subjected to painful stimulation or immobilization stress 30 min after the treatment. To determine the degree of oxidative stress, the levels of free radicals, thiobarbituric acid reactive substances (TBARS) as indicators of lipid peroxidation and glutathione peroxidase (GSHPx) were estimated in somatosensory cortex. Pain perception was measured by the tail-flick and plantar test. Melatonin reduced the level of TBARS previously increased by painful stimulation. Melatonin also exhibited a slight analgesic effect in those animals exposed to painful stimulation but its role in free radical scavenging did not contribute to this effect.

Decreased protein levels of complex I 30-kDa subunit in fetal Down syndrome brains.

Defects of mitochondrial electron transport enzymes have been implicated in the pathogenesis of several neurodegenerative diseases. In previous work, we reported decreased protein levels of mitochondrial electron transport enzyme subunits in adult brain with Down syndrome (DS). However it is not clear whether cellular damage due to mitochondrial defects in brain of DS fetus begins in utero. Here we investigated the protein levels of mitochondrial electron transport enzymes in fetal DS brain using the proteomic technologies. Two-dimensional (2-D) gel electrophoresis, matrix-assisted laser desorption ionization mass spectroscopy (MALDI-MS) and specific software for quantification were used. The protein levels of complex I 30-kDa subunit were significantly decreased in cerebral cortex of fetal DS brain. We conclude that decreased mitochondrial electron transport enzyme subunits in fetal DS brains could contribute to the impaired energy and free radical metabolism affecting brain development in DS fetus. Furthermore, the defects of mitochondrial electron enzymes shown in adult DS brains could begin in utero and continue during the life span of the individual with DS.