Membrane adenosine triphosphatase of Escherichia coli: activation by calcium ion and inhibition by monovalent cations

Neuroprotective aftermath of Monodora myristica and Glycyrrhiza glabra against cassava diet containing vacuum gas oil induced brain injury in Wistar rats

Vacuum gas oil (VGO) is a hydrocarbon combination formed during crude oil extraction, and its consumption may have neurological repercussions. This study investigated the neuroprotective properties of Monodora myristica and Glycyrrhiza glabra in rats given cassava flour diet containing vacuum gas oil (CFD-VGO). Thirty rats were separated into six groups and treated as follows: Group 1 severed as normal control. Group 2 were fed CFD-VGO only. After a normal diet was given to groups 3, 4, and 5, M. myristica, G. glabra, and M. myristica plus G. glabra extracts were administered. Group 6, 7, 8 and 9 were given CFD-VGO and then treated with M. myristica extract, G. glabra extract, M. myristica plus G. glabra extracts and 2-methyl cellulose respectively. The rats were euthanized using carbon dioxide after experimental period of 28 days. The brain was excised for biochemical assays. The results showed that the concentration of the assessed 16 PAHs in CFD-VGO using GC-MS was 53.38 ppm. Significant (p < 0.05) increase were observed in malondialdehyde (MDA), total cholesterol (T.Chl), triacylglycerol (TAG), low density lipoprotein-cholesterol (LDL-C), and decrease in high density lipoprotein-cholesterol (HDL-C), acetylcholinesterase (AChE) and ATPases in the brain rats fed with CFD-VGO. On the other hand, administration of M. myristica and G. glabra extract effectively restored altered antioxidants, ATPases, and lipids in brain of rats fed with cassava diet containing VGO.

The effects of eugenol on histological, enzymatic, and oxidative parameters in the major salivary glands and pancreas of healthy male Wistar rats

OBJECTIVE

We evaluated the effects of eugenol on histological, enzymatic, and oxidative parameters in the pancreas, parotid, submandibular, and sublingual glands of healthy male rats.

DESIGN

Twenty-four adult Wistar rats were assigned into four groups (n = 6/group). Control rats received 2% Tween-20 (eugenol vehicle), whereas the other animals received 10, 20, and 40 mg kg-1 eugenol through gavage daily for 60 d. Major salivary and pancreatic glands were weighed and preserved fixed for microscopic analysis and frozen for in vitro assays.

RESULTS

Eugenol did not alter glands' weight and serum amylase activity regardless of the concentration. The highest dose of eugenol caused an increase in pancreatic amylase activity and a reduction of lipase activity from serum and pancreas. Eugenol at 40 mg kg-1 diminished the activity of SOD and FRAP in the submandibular gland and CAT and FRAP in the sublingual gland. However, it did not exert any effect on GST regardless of the gland. Additionally, 40 mg kg-1 eugenol increased MDA levels in pancreatic, parotid, and submandibular glands and NO levels in the sublingual. The concentrations of eugenol induced distinct responses in the glands regarding the activity of Na+/K+, Mg2+, and total ATPase activity. They also affected histomorphometrical and histochemistrical parameters in the submandibular gland only.

CONCLUSIONS

Results indicated that 40 mg kg-1 eugenol altered most of the biochemical and oxidatived parameters of digestive glands. Only submandibular glands presented histological changes after eugenol exposure suggesting potential implications for its function.

The role of pyrethroid derivatives in autophagy and apoptosis crosstalk signaling and potential risk for malignancies

Pyrethroids and its derivatives widespread and uncontrolled continuous use has influenced multiple deleterious effects resulting in as a potential risk factor causing damage to the organ systems. Allethrin and prallethrin are extensively used yet their influences on human primary cells are very limited or under reported. The potential mechanisms by which allethrin and prallethrin modulates human primary cells, especially the molecular mechanisms or interconnectivity of autophagy-apoptosis, their clinical relevance in human subjects or patients are not well defined. In this current study, we've furnished the evidence that both allethrin and prallethrin user samples significantly induced Ccl2 mRNA expression, increased amount of reactive oxygen intermediate, inhibited membrane bound enzymes and altered membrane fluidity. Pyrethroid derivative users had induced levels of lipid peroxidation and induced binding activities of transcription factors(tfs) like CEBP-β and NF-AT. Pyrethroid derivatives induced autophagy, elicited intracellular Ca2+ concentration, calcineurin and regulated proapoptotic genes, DAPK1, Bim. Our current study presumably comprises the initial investigation of a very new mechanism of pyrethroid derivatives-moderated programed cell death in various cell sets or types, like human primary cells where-in this is a late event, is documented. Hence, current research-study might be significant in the various pyrethroid derivatives-allied hematological-related cancers and immunosuppressant or auto-immune disorders. In the foremost instance, we present data stating that pyrethroid derivatives induces multiple cell signaling cascades, like CEBP-β, NF-AT, ERK and MAPK having a role in autophagy thereby; synchronously effectively impact on the apoptosis, therefore causing hematological tumors and toxic or immune related disorders.

Prevention and reversal of chlorpromazine induced testicular dysfunction in rats by synergistic testicle-active flavonoids, taurine and coenzyme-10

Evidences have shown that alterations in testicular dehydrogenase and ionic-ATPase activities have important implications in spermatogenesis and sperm capacitation, a penultimate biochemical change required for fertilization. Previous studies have revealed that taurine and coenzyme-Q10 (COQ-10), which are synergistic testicle-active bioflavonoids, with proven gonadotropin-enhancing properties reduce testicular damage in rats. Hence, this study investigated the effects of taurine and COQ-10 or their combination alone, and in the preventive and reversal of chlorpromazine-induced inhibition of testicular dehydrogenase enzymes, electrogenic pumps, sperm capacitation and acrosomal-reaction in male Wister rats. In the drug-treatment alone or preventive-protocol, rats received oral treatment of saline (10 mL/kg), taurine (150 mg/kg/day), COQ-10 (10 mg/kg/day) or both alone repeatedly for 56 days, or in combination with chlorpromazine (30 mg/kg/p.o./day) from days 29-56. In the reversal-protocol, the animals received chlorpromazine for 56 days prior to saline, taurine, COQ-10 or the combination from days 29-56. Thereafter, spermatogenesis (sperm count, viability, motility and morphology), testicular dehydrogenase [3beta-hydroxysteroid dehydrogenase (3ß-HSD), 17beta-hydroxysteroid dehydrogenase (17ß-HSD), glucose-6-phosphate dehydrogenase (G6PDH), lactate dehydrogenase-X (LDH-X)], ATPase (Na⁺/K⁺, Ca²⁺, Mg²⁺, H⁺) activities, sperm capacitation and acrosomal reaction were evaluated. Taurine and COQ-10 or their combination increased spermatogenesis, testicular 3ß-HSD, 17ß-HSD, G6PDH and LDH-X enzymes of naïve and chlorpromazine-treated rats. Both taurine and COQ-10 increased Na⁺/K⁺, Ca²⁺, Mg²⁺ and H⁺-ATPase activities. Also, taurine and COQ-10 or their combination prevented and reversed chlorpromazine-induced inhibition of sperm capacitation and acrosomal-reaction. The study showed that taurine and COQ-10 prevent and reverse chlorpromazine-induced inhibition of spermatogenesis, epididymal sperm capacitation and acrosomal reaction in rats through increased testicular dehydrogenases and electrogenic pump activities.

Modulatory Role of Vitamin E on Proton Pump (ATPase) Activity of Cadmium Chloride-Induced Testicular Damage in Wistar Rats

Proton pumps are membrane-bound enzymes important in generating gradients that help in maintaining cellular ion homeostasis, cell membrane potential, water, and solute transport across the cell surface. This study investigated the modulatory role of vitamin E on proton pump activity and reproductive parameters in cadmium-induced testicular damage. Twenty (20) male Wistar rats weighing between 180 and 200 g were sorted into 4 groups of five rats each. Group I served as the control and was given normal saline orally, Group II rats were treated with a single dose of 2 mg/kg BW cadmium chloride (CdCl2) intraperitoneally, Group III rats were given 100 mg/kg BW of vitamin E orally, and Group IV rats were given 100 mg/kg BW of vitamin E orally for 30 days prior to intraperitoneal administration of single dose of 2 mg/kg BW of cadmium chloride. The rats were anaesthetized with diethyl ether, and blood samples were obtained for sex hormonal analysis; caudal epididymis was dissected for sperm count, motility, and viability, and the testis were homogenized for lipid peroxidation and proton pump (Na+/K+ ATPase, Ca2+ ATPase, and Mg2+ ATPase) activity. Proton pump activity was assayed spectrophotometrically using the Stewart method to determine the inorganic phosphate level. Histopathological changes of the testis were also studied. The group treated with CdCl2 showed a significant (p < 0.05) decrease in proton pump activity, sperm count, and motility and a significant (p < 0.05) increase in malondialdehyde level when compared with the control group. The CdCl2-treated group also showed decrease reproductive organ weights and hormonal levels and cause necrosis of spermatogonia lining the seminiferous tubules. Rats treated with vitamin E orally for 30 days prior to CdCl2 exposure showed improvement in proton pump activity, a significant (p < 0.05) increase in sperm parameters and luteinizing hormonal level, and a decrease in the lipid peroxidation level as compared with the CdCl2 group. This study showed that vitamin E ameliorated the toxic effect of CdCl2 on proton pump activity in the testes, hence improving testicular integrity, structures, and functions.

Morin treatment for acute ethanol exposure in rats

Ethanol intoxication increases oxidative stress and pro-inflammatory proteins, which cause neurodegeneration. Morin is a natural flavonoid obtained from plants of the Moraceae family that exhibits antioxidant, anti-inflammatory, hepatoprotective, anticancer and cardioprotective properties. We investigated the neuroprotective effect of morin on ethanol intoxicated rats. Rats exposed to ethanol exhibit increased cholesterol, triglycerides, phospholipids, free fatty acids, and lipid oxidative byproducts, and decreased the activity of antioxidant enzymes and membrane ATPase. We found that ethanol increased activation of microglia and astrocytes in the brain. Administration of morin to rats exposed to ethanol significantly decreased lipid oxidative byproducts, enhanced antioxidant enzymes, normalized lipid levels and decreased microglia and astrocyte activation. Morin exhibits neuroprotective properties against ethanol intoxication by increasing the antioxidant defense mechanism and decreasing the inflammatory response caused by neuroglia and astrocytes.

Quercetin modulates granulosa cell mRNA androgen receptor gene expression in dehydroepiandrosterone-induced polycystic ovary in Wistar rats via metabolic and hormonal pathways

Background It is estimated that about 5-10% of women suffer from polycystic ovarian syndrome (PCOS) which is a major cause of female reproductive dysfunction. This study examined the role of quercetin on dehydroepiandrosterone (DHEA)-induced PCO in Wistar rats. Methods Twenty-eight pre-pubertal female Wistar rats that are 21 days old weighing 16-21 g were sorted into four groups (n = 7). Group I served as control and was given distilled water only, Group II were injected with 6 mg/100 g BW of DHEA in 0.2 mL of corn oil subcutaneously, Group III received 100 mg/kg BW of quercetin orally and Group IV received 6 mg/100 g BW of DHEA in 0.2 mL of corn oil subcutaneously and 100 mg/kg BW of quercetin orally. Rats were sacrificed after 15 days by cervical dislocation method. Blood samples and ovaries were collected for hormonal, biochemical, and histopathological analysis and expressions of mRNA androgen receptor gene were determined using RT-qPCR. All data were analysed using one-way ANOVA. Results A significant decrease (p < 0.05) in the antioxidant and metabolic enzyme activity in the DHEA treated group was observed when compared with control. DHEA co-administration with quercetin showed a significant decrease in malondialdehyde and cytokines when compared with DHEA treated group. Also a significant increase in progesterone, metabolic and antioxidant enzyme activity was observed. The histopathology demonstrates a reduction in cystic and atretic cells, improved expression of BCl2, E-Cadherin and a decrease in Bax. Conclusions Quercetin alleviated DHEA-induced PCO. These effects could be attributed to its antioxidant property.

Ovarian Metabolic activity in Dehydroepiandrosterone-Induced Polycystic Ovary in Wistar rats Treated with Aspirin

OBJECTIVES

Polycystic ovary syndrome (PCOS) represents 75% of the cases of anovulatory infertility. The aim of this study was to investigate the role of aspirin on dehydroepiandrosterone (DHEA) - induced polycystic ovary syndrome in Wistar rats.

METHODS

Twenty eight (28) pre-pubertal female Wistar rats of 21 days old weighing 16 - 21 g were divided into 4 groups (7 rats/group) and treated as follows; group I received distilled water and served as Control; Group II received 6 mg/100 g body weight DHEA in 0.2 ml of oil subcutaneously to induce PCOS. Group III received 7.5 mg/kg of aspirin orally; Group IV received 6 mg/100kg of body weight of DHEA in 0.2ml of oil subcutaneously and 7.5 mg/kg of aspirin orally. After 15 days of administration, the rats were slaughtered by cervical dislocation. Blood samples and ovaries were collected for reproductive hormonal analysis, biochemical and histopathological analysis. The expressions of mRNA androgen receptor (AR) gene in the ovary were determined by real time reverse transcriptase polymerase chain reaction (qPCR). All the data was analyzed using one way ANOVA with the Graph pad prism software version 6. A p<0.05 was considered significant.

RESULTS

The results obtained showed that dehydroepiandrosterone treatment caused significant decrease (p<0.05) in total protein, superoxide Dismutase (SOD), glutathione-s- transferase (GST), Ca2+ ATPase, and significant increase (p<0.05) in malondialdehyde, vascular endothelial growth factor, tumor necrosis factor and estrogen as compared to Controls. The group co-administered with DHEA and aspirin showed significant increases in SOD, GST, CAT, GSH, Progesterone, Ca2+ ATPase, Na+ ATPase, H+ ATPase and significant reduction (p<0.05) in malondialdehyde, VEGF, TNF-α and estrogen as compared with the DHEA group. The histopathological analysis showed reductions in cystic fibrosis, atretic ovaries, increased expression of Bcl-2 and E- Cadherin and reduced Bax expression in the group that received Aspirin and DHEA.

CONCLUSION

This study clearly demonstrates that Aspirin has ameliorating effects against polycystic ovary syndrome via anti-inflammatory and hormonal modulatory pathways.

Vitamin C suppresses ovarian pathophysiology in experimental polycystic ovarian syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS), also known as the Stein-Leventhal syndrome is one of the most common causes of anovulation, infertility and hyperandrogenism in women, affecting between 5-10 % of women of reproductive age (12-35 years) worldwide. Despite substantial effort to define the cause of PCOS, its pathophysiology remains poorly understood. Consequently, determining the mechanisms of PCOS and the possible treatment is the major goal of medical research in endocrine and reproductive physiology.

AIM

To investigate the mechanism of ovarian metabolic changes in dehydroepiandrosterone (DHEA)-induced polycystic ovary in Wistar rats treated with vitamin C.

METHODS

Twenty-eight immature female Wistar rats weighing (16-21 g) were randomly divided into four groups (n = 7/group): group I served as control and was given water, group II were injected with DHEA (6 mg/100 g in 0.2 ml corn oil subcutaneously to induce PCOS condition), group III received 150 mg/kg BW of Vitamin C orally, group IV were co-administered with 6 mg/kg BW DHEA in 0.2 ml of corn oil subcutaneously and 150 mg/kg BW of Vitamin C orally. All treatments lasted for 15 days. Twenty-four hours after the last administration, the rats were sacrificed by cervical dislocation. Blood samples and ovaries were collected for reproductive hormonal analysis, biochemical and histopathological analysis. The expressions of mRNA androgen receptor gene in the ovary were determined by real-time reverse transcriptase polymerase chain reaction. All data were analysed using one-way ANOVA.

RESULTS

There was a significant decrease (p < 0.05) in the antioxidant and metabolic enzyme activity in the DHEA treated group compared with the control group. DHEA co-administration with Vitamin C showed a significant decrease in Malondialdehyde, cytokines and Estrogen and a significant increase (p < 0.05) in antioxidant and metabolic enzymes compared with DHEA treated group only. The histopathological evaluation demonstrates a reduction in cystic and atretic ovaries, increased expression of Bcl₂ and E-Cadherin with a reduction in Bax expression in the group co-administered with DHEA and Vitamin C. The DHEA group showed overexpression of mRNA Androgen Receptor gene in the ovaries compared to the control group.

CONCLUSION

This study shows that Vitamin C plays a protective role against DHEA-Induced Polycystic Ovary in Wistar rats via its antioxidant and anti-apoptotic mechanisms.

Protective effects of methanol extract of Plukenetia conophora seeds and 4H-Pyran-4-One 2,3-Dihydro-3,5-Dihydroxy-6-Methyl on the reproductive function of male Wistar rats treated with cadmium chloride

OBJECTIVES

Male infertility caused by exposure to heavy metals is a current global issue. Exposure to cadmium chloride (CdCl2) negatively affects the male reproductive system. Many infertile people, especially in developing countries, resort to folkloric treatment. Plukenetia conophora is used in Nigerian folk medicine to promote fertility. This study investigated the effects of Plukenetia conophora (PC) and 4H-Pyran-4-One 2,3-Dihydro-3,5-Dihydroxy-6-Methyl (DDMP) on Wistar rats with cadmium chloride-induced testicular damage.

METHODS

Forty-two male Wistar rats (150-190g) were divided into seven groups (n=6) and treated daily for 54 days as follows: Controls (normal saline); CdCl2 (2mg/kg single IP dose); CdCl2 + 200 mg/kg vitamin E; CdCl2 + 100 or 200 mg/kg PC; and CdCl2 + 25 or 50 mg/kg DDMP. The rats were sacrificed 55 days after the start of the study; Samples were collected for analysis. Biochemical parameters malondialdehyde, nitric oxide, antioxidant enzymes, and proton pumps were measured by spectrophotometry. Reproductive hormones were measured using ELISA. Data were analysed using ANOVA and differences in mean values were considered significant at p<0.05.

RESULTS

Significant increases in sperm count, motility, and viability were observed in the groups given CdCl2+Vitamin E, CdCl2+PC or CdCl2+DDMP as compared with the CdCl2 group. Malondialdehyde and nitric oxide levels in the groups treated with CdCl2+PC or CdCl2+DDMP decreased significantly when compared with the group given CdCl2. Significant increases were observed in antioxidant enzymes, proton pump, and testosterone in the groups treated with CdCl2+PC or CdCl2+DDMP, respectively.

CONCLUSION

Plukenetia conophora alleviated male reproductive toxicity induced by cadmium chloride in Wistar rats. 4H-Pyran-4-One 2,3-Dihydro-3,5-Dihydroxy-6-Methyl present in Plukenetia conophora may be responsible for the ameliorative effects.

Cytochromes bd-I and bo3 are essential for the bactericidal effect of microcin J25 on Escherichia coli cells

Microcin J25 has two targets in sensitive bacteria, the RNA polymerase, and the respiratory chain through inhibition of cellular respiration. In this work, the effect of microcin J25 in E. coli mutants that lack the terminal oxidases cytochrome bd-I and cytochrome bo₃ was analyzed. The mutant strains lacking cytochrome bo₃ or cytochrome bd-I were less sensitive to the peptide. In membranes obtained from the strain that only expresses cytochrome bd-I a great ROS overproduction was observed in the presence of microcin J25. Nevertheless, the oxygen consumption was less inhibited in this strain, probably because the oxygen is partially reduced to superoxide. There was no overproduction of ROS in membranes isolated from the mutant strain that only express cytochrome bo₃ and the inhibition of the cellular respiration was similar to the wild type. It is concluded that both cytochromes bd-I and bo₃ are affected by the peptide. The results establish for the first time a relationship between the terminal oxygen reductases and the mechanism of action of microcin J25.

Diallyl trisulfide, a garlic polysulfide protects against As-induced renal oxidative nephrotoxicity, apoptosis and inflammation in rats by activating the Nrf2/ARE signaling pathway

BACKGROUND

Arsenic (As) contamination is an extremely dangerous global environmental problem as it can enter into the food chain and become bio-accumulated, endangering human health. Chronic As intoxication leads to undesirable toxic effects in various organ systems of the body, especially the kidney. Diallyl trisulfide (DATS) is an organosulfur compound which has been widely known for its uses as antibacterial, antitumorogenic, antioxidant agent and has been also reported to have anti-apoptotic and anti-inflammatory properties.

PURPOSE

In the present work, we intend to investigate the protective role of DATS, a garlic organosulfur compound in preventing the As-induced oxidative stress mediated renal injury in rats. Study design The activity of DATS to antagonize As-induced renal oxidative toxicity was analyzed using rats as an in vivo model.

METHODS

We investigated the nephroprotective effect of DATS on As treated rats by performing various serological, biochemical, molecular and histological studies. The activation of Nrf2 was investigated using western blot.

RESULTS

The data showed that As exposure significantly increased the serum and urine nephritic, oxidative stress, apoptosis and inflammatory markers in the renal tissue of rats. As intoxication also decreased the antioxidant status of the renal tissue along with the disturbances in the membrane bound ATPases. As nephrotoxicity was further confirmed with the altered morphological and ultrastructural changes in the renal tissue. Conversely, the DATS pre-administration effectively recuperate the altered renal variables by As, which has been further supported by the histological and ultrastructural observations. This counteraction was achieved partially via the activation of Nrf2-ARE pathway through the activation of Akt.

CONCLUSION

These findings explicate the prospective use of DATS as a promising organosulfur compound against As-induced renal oxidative dysfunction in rats.

Neuroprotective efficacy of hesperetin against cadmium induced oxidative stress in the brain of rats

The present study was designed to investigate the neuroprotective effect of hesperetin (Hp) against cadmium (Cd)-induced neurotoxicity in rats. Cadmium (3 mg/kg body weight (b.w.), subcutaneous) administration for 3 weeks demonstrated neurotoxicity in rats by the decreased activity of acetylcholinesterase in the brain. The oxidative stress markers (thiobarbituric acid reactive substances and protein carbonyls) were significantly increased with decreased enzymatic (superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase) and non-enzymatic antioxidants (reduced glutathione, total sulphydryl groups and vitamin C). The proteolytic and membrane-bound enzymes (Na⁺ K⁺-ATPase, Mg²⁺-ATPase and Ca²⁺-ATPase) were also decreased with increased apoptotic markers (Bcl2 Associated X Protein (Bax), cytochrome C, caspase 3 and 9) and decreased anti-apoptotic marker (B-cell lymphoma 2 (Bcl2)) in the brain of Cd-treated rats. Moreover, Cd administration significantly decreased the mitochondrial electron transport chain complexes (I, II, III and IV) in the brain of rats. Preadministration of Hp (40 mg/kg b.w., oral) significantly attenuated the Cd-induced oxidative stress and mitochondrial dysfunction, restored the antioxidant and membrane-bound enzyme activities and decreased apoptosis in the brain of rats.

Assessment of hepatoprotective and nephroprotective potential of withaferin A on bromobenzene-induced injury in Swiss albino mice: possible involvement of mitochondrial dysfunction and inflammation

Bromobenzene is a well-known environmental toxin which causes liver and kidney damage through CYP450-mediated bio-activation to generate reactive metabolites and, consequently, oxidative stress. The present study aimed to evaluate the possible protective role of withaferin A against bromobenzene-induced liver and kidney damage in mice. Withaferin A (10 mg/kg) was administered orally to the mice for 8 days before intragastric intubation of bromobenzene (10 mmol/kg). As results of this experiment, the levels of liver and kidney functional markers, lipid peroxidation, and cytokines (TNF-α and IL-1β) presented an increase and there was a decrease in anti-oxidant activity in the bromobenzene-treated group of mice. Pre-treatment with withaferin A not only significantly decreased the levels of liver and kidney functional markers and cytokines but also reduced oxidative stress, as evidenced by improved anti-oxidant status. In addition, the mitochondrial dysfunction shown through the decrease in the activities of mitochondrial enzymes and imbalance in the Bax/Bcl-2 expression in the livers and kidneys of bromobenzene-treated mice was effectively prevented by pre-administration of withaferin A. These results validated our conviction that bromobenzene caused liver and kidney damage via mitochondrial pathway and withaferin A provided significant protection against it. Thus, withaferin A may have possible usage in clinical liver and kidney diseases in which oxidative stress and mitochondrial dysfunction may be existent.

ATP Synthesis by Oxidative Phosphorylation

The F1F0-ATP synthase (EC 3.6.1.34) is a remarkable enzyme that functions as a rotary motor. It is found in the inner membranes of Escherichia coli and is responsible for the synthesis of ATP in response to an electrochemical proton gradient. Under some conditions, the enzyme functions reversibly and uses the energy of ATP hydrolysis to generate the gradient. The ATP synthase is composed of eight different polypeptide subunits in a stoichiometry of α3β3γδεab2c10. Traditionally they were divided into two physically separable units: an F1 that catalyzes ATP hydrolysis (α3β3γδε) and a membrane-bound F0 sector that transports protons (ab2c10). In terms of rotary function, the subunits can be divided into rotor subunits (γεc10) and stator subunits (α3β3δab2). The stator subunits include six nucleotide binding sites, three catalytic and three noncatalytic, formed primarily by the β and α subunits, respectively. The stator also includes a peripheral stalk composed of δ and b subunits, and part of the proton channel in subunit a. Among the rotor subunits, the c subunits form a ring in the membrane, and interact with subunit a to form the proton channel. Subunits γ and ε bind to the c-ring subunits, and also communicate with the catalytic sites through interactions with α and β subunits. The eight subunits are expressed from a single operon, and posttranscriptional processing and translational regulation ensure that the polypeptides are made at the proper stoichiometry. Recent studies, including those of other species, have elucidated many structural and rotary properties of this enzyme.

Attenuation of erythrocyte membrane oxidative stress by Sesbania grandiflora in streptozotocin-induced diabetic rats

The aim of the present study was to investigate the protective effects of Sesbania grandiflora flower (SGF) extract on erythrocyte membrane in Streptozotocin (STZ)-induced diabetic rats. Adult male albino rats of Wistar strain, weighing 190-220 g, were made diabetic by an intraperitonial administration of STZ (45 mg/kg). Normal and diabetic rats were treated with SGF, and diabetic rats were also treated with glibenclamide as drug control, for 45 days. In this study plasma insulin and haemoglobin levels were decreased and blood glucose, glycosylated haemoglobin, protein oxidation, lipid peroxidation markers, and osmotic fragility levels were increased in diabetic rats. Moreover, erythrocytes antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxide, glutathione reductase, glutathione-S-transferase, and glucose-6-phosphate dehydrogenase activities and non-enzymatic antioxidants such as vitamin C, vitamin E, reduced glutathione (GSH), and oxidized glutathione (GSSG) levels were altered. Similarly, the activities of total ATPases, Na(+)/K(+)-ATPase, Ca(2+)-ATPase, and Mg(2+)-ATPase were also decreased in the erythrocytes of diabetic rats. Administration of SGF to STZ-induced diabetic rats reduced blood glucose and glycosylated haemoglobin levels with increased levels of insulin and haemoglobin. Moreover, SGF reversed the protein and lipid peroxidation markers, osmotic fragility, membrane-bound ATPases activities, and antioxidant status in STZ-induced diabetic rats. These results suggest that SGF could provide a protective effect on diabetes by decreasing oxidative stress-associated diabetic complications.

Grape seed proanthocyanidins ameliorates cadmium-induced renal injury and oxidative stress in experimental rats through the up-regulation of nuclear related factor 2 and antioxidant responsive elements

Cadmium (Cd) preferentially accumulates in the kidney, the major target for Cd-related toxicity. Cd-induced reactive oxygen species (ROS) have been considered crucial mediators for renal injury. The biologically significant ionic form of cadmium (Cd+) binds to many bio-molecules, and these interactions underlie the toxicity mechanisms of Cd. The present study was hypothesized to explore the protective effect of grape seed proanthocyanidins (GSP) on Cd-induced renal toxicity and to elucidate the potential mechanism. Male Wistar rats were treated with Cd as cadmium chloride (CdCl2, 5 mg·kg−1 bw, orally) and orally pre-administered with GSP (100 mg·kg−1 bw) 90 min before Cd intoxication for 4 weeks to evaluate renal damage of Cd and antioxidant potential of GSP. Serum renal function parameters (blood urea nitrogen and creatinine) levels in serum and urine, renal oxidative stress (lipid peroxidation, protein carbonylation, enzymatic, and non-enzymatic antioxidants), inflammatory (NF-κB p65, NO, TNF-α, IL-6), apoptotic (caspase-3, caspase-9, Bax, Bcl-2), membrane bound ATPases, and Nrf2 (HO-1, keap1, γ-GCS, and μ-GST) markers were evaluated in Cd-treated rats. Pretreatment with GSP revealed a significant improvement in renal oxidative stress markers in kidneys of Cd-treated rats. In addition, GSP treatment decreases the amount of iNOS, NF-κB, TNF-α, caspase-3, and Bax and increases the levels Bcl-2 protein expression. Similarly, mRNA and protein analyses substantiated that GSP treatment notably normalizes the renal expression of Nrf2/Keap1 and its downstream regulatory proteins in the Cd-treated rats. Histopathological and ultra-structural observations also demonstrated that GSP effectively protects the kidney from Cd-induced oxidative damage. These findings suggest that GSP ameliorates renal dysfunction and oxidative stress through the activation of Nrf2 pathway in Cd-intoxicated rats.

Influence of kaempferol, a flavonoid compound, on membrane-bound ATPases in streptozotocin-induced diabetic rats

CONTEXT

Kaempferol is a flavonoid found in many edible plants (e.g. tea, cabbage, beans, tomato, strawberries, and grapes) and in plants or botanical products commonly used in traditional medicine. Numerous preclinical studies have shown that kaempferol have a wide range of pharmacological activities, including antioxidant, anti-inflammatory, anticancer, cardioprotective, neuroprotective, and antidiabetic activities.

OBJECTIVE

The present study investigates the effect of kaempferol on membrane-bound ATPases in erythrocytes and in liver, kidney, and heart of streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

Diabetes was induced into adult male albino rats of the Wistar strain, by intraperitoneal administration of STZ (40 mg/kg body weight (BW)). Kaempferol (100 mg/kg BW) or glibenclamide (600 µg/kg BW) was administered orally once daily for 45 d to normal and STZ-induced diabetic rats. The effects of kaempferol on membrane-bound ATPases (total ATPase, Na(+)/K(+)-ATPase, Ca(2+)-ATPase, and Mg(2+)-ATPase) activity in erythrocytes and in liver, kidney, and heart were determined.

RESULTS

In our study, diabetic rats had significantly (p < 0.05) decreased activities of total ATPases, Na(+)/K(+)-ATPase, Ca(2+)-ATPase, and Mg(2+)-ATPase in erythrocytes and tissues. Oral administration of kaempferol (100 mg/kg BW) or glibenclamide (600 µg/kg BW) for a period of 45 d resulted in significant (p < 0.05) reversal of these enzymes' activities to near normal in erythrocytes and tissues when compared with diabetic control rats.

DISCUSSION AND CONCLUSION

Thus, obtained results indicate that administration of kaempferol has the potential to restore deranged activity of membrane-bound ATPases in STZ-induced diabetic rats. Further detailed investigation is necessary to discover kaempferol's action mechanism.

Vitamin K1 alleviates streptozotocin-induced type 1 diabetes by mitigating free radical stress, as well as inhibiting NF-κB activation and iNOS expression in rat pancreas

OBJECTIVE

The aim of this study was to understand the mechanism of action of vitamin K1 against streptozotocin (STZ)-induced diabetes.

METHODS

Male Wistar rats were administered 35 mg/kg STZ and after 3 d were treated with vitamin K1 (5 mg/kg, twice a week) for 3 months. Blood glucose was monitored twice a month. At the end of the study, animals were sacrificed and pancreas dissected out and analyzed for free radicals, antioxidants, metabolic enzymes related to glucose, membrane ATPases, histopathological evaluation, and expression of nuclear factor (NF)-κB and inducible nitric oxide synthase (iNOS). Glycated hemoglobin, plasma insulin, and islet area were determined at the end of the study.

RESULTS

Treatment of STZ-induced type 1 diabetic rats with vitamin K1 reduced oxidative stress, enhanced antioxidants, and inhibited aldose reductase in pancreas. Vitamin K1 administration rescued endocrine pancreas from STZ-induced cell death, resulting in enhanced insulin secretion and normal blood glucose and glycosylated hemoglobin levels. Histologic analyses also showed the antidiabetic potential of vitamin K1. Measure of pancreatic islet area showed an increase in the islet area upon vitamin K1 treatment when compared with the STZ-administered group, suggesting the possibility of regeneration. To understand the mechanism involved in vitamin K1 mediated changes, we performed immunohistochemical analyses for NF-κB and iNOS enzyme. Vitamin K1 was shown to suppress NF-κB activation and iNOS expression in the islets upon administration of STZ.

CONCLUSION

This work shows, to our knowledge for the first time, the mechanism of action of vitamin K1 against type 1 diabetes and the possible therapeutic use of this vitamin in stimulating islet cell proliferation/regeneration.

Epigallocatechin gallate supplementation protects against renal injury induced by fluoride intoxication in rats: Role of Nrf2/HO-1 signaling

Fluoride intoxication generates free radicals, causing oxidative stress that plays a critical role in the progression of nephropathy. In the present study, we hypothesized that epigallocatechin gallate (EGCG), found in green tea, protects the kidneys of rats treated with fluoride by preventing oxidative stress, inflammation, and apoptosis. Pretreatment of fluoride-treated rats with EGCG resulted in a significant normalization of creatinine clearance and levels of urea, uric acid, and creatinine. Fluoride intoxication significantly increased renal oxidative stress markers and decreased the levels of renal enzymatic and non-enzymatic antioxidants. In addition, renal NO, TNF-α, IL-6 and NF-κB were also increased in the renal tissue of fluoride-treated rats. Further, EGCG pretreatment produced a significant improvement in renal antioxidant status and reduced lipid peroxidation, protein carbonylation and the levels of inflammatory markers in fluoride-treated kidney. Similarly, mRNA and protein analyses showed that EGCG pretreatment normalized the renal expression of Nrf2/Keap1 and its downstream regulatory proteins in fluoride-treated rat kidney. EGCG also effectively attenuated fluoride-induced renal apoptosis by the up-regulation of anti-apoptotic proteins such as Bcl-2 and down-regulation of Bax, caspase-3, caspase-9 and cytochrome c. Histology and immunohistochemical observations of Kim-1 provided further evidence that EGCG effectively protects the kidney from fluoride-mediated oxidative damage. These results suggest that EGCG ameliorates fluoride-induced oxidative renal injury by activation of the Nrf2/HO-1 pathway.

Effect of 2-Hydroxy-4-methoxy Benzoic Acid Isolated from Hemidesmus indicus on Erythrocyte Membrane Bound Enzymes and Antioxidant Status in Streptozotocin-induced Diabetic Rats

In the present study, the effect of 2-hydroxy-4-methoxy benzoic acid isolated from roots of Hemisdesmus indicus on the erythrocyte membrane bound enzymes and antioxidant status in streptozotocin-induced diabetic rats was investigated. The streptozotocin-induced diabetic rats were treated with 2-hydroxy-4-methoxy benzoic acid (500 μg/kg/day) for 7 weeks by oral intubation and compared with glibenclamide, a standard hypoglycemic agent (100 mg/kg). The erythrocyte membrane was isolated and the activity of Na(+)/K(+)-dependent ATPases, Ca(2+)-ATPases, Mg(2+)-ATPases were determined. Superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase, vitamins C, vitamin E, plasma reduced glutathione and erythrocyte glutathione, reduced glutathione content in the tissues was also assayed. Administration of 2-hydroxy-4-methoxy benzoic acid to diabetic rats significantly (F>0.05 and P<0.001) elevated the activity of total ATPases, Na(+)/k(+) ATPase, Mg(2+) ATPase and Ca(2+) ATPase to near normal level. The activities of catalase, superoxide dismutase and glutathione peroxidase and glutathione-S-transferase in erythrocytes were decreased significantly (F>0.05; P<0.001) in diabetic rats. Diabetic rats treated with 2-hydroxy-4-methoxy benzoic acid showed a significant (F>0.05; <0.001) increase in the enzymic antioxidants in erythrocytes. The elevated levels of vitamin E and low level of vitamin C and glutathione level in plasma and erythrocytes were observed in diabetic rats when compared to control rats and were restored significantly (F>0.05; P<0.001) after the administration of 2-hydroxy-4-methoxy benzoic acid. This study concludes administration of 2-hydroxy-4-methoxy benzoic acid supports the restoration of antioxidant defence, reduces the free radial production, lipid peroxidation and the glycosylation of haemoglobin in diabetic rats.

The WaaL O-antigen lipopolysaccharide ligase has features in common with metal ion-independent inverting glycosyltransferases

WaaL is a membrane enzyme that catalyzes a key step in lipopolysaccharide (LPS) synthesis: the glycosidic bonding of a sugar at the proximal end of the undecaprenyl-diphosphate (Und-PP) O-antigen with a terminal sugar of the lipid A-core oligosaccharide (OS). Utilizing an in vitro assay, we demonstrate here that ligation with purified Escherichia coli WaaL occurs without adenosine-5'-triphosphate (ATP) and magnesium ions. Furthermore, E. coli and Pseudomonas aeruginosa WaaL proteins cannot catalyze ATP hydrolysis in vitro. We also show that a lysine substitution of the arginine (Arg)-215 residue renders an active protein, whereas WaaL mutants with alanine replacements in the periplasmic-exposed residues Arg-215, Arg-288 and histidine (His)-338 and also the membrane-embedded aspartic acid-389 are nonfunctional. An in silico approach, combining predicted topological information with the analysis of sequence conservation, confirms the importance of a positive charge at the small periplasmic loop of WaaL, since an Arg corresponding to Arg-215 was found at a similar position in all the WaaL homologs. Also, a universally conserved H[NSQ]X(9)GXX[GTY] motif spanning the C-terminal end of the predicted large periplasmic loop and the membrane boundary of the transmembrane helix was identified. The His residue in this motif corresponds to His-338. A survey of LPS structures in which the linkage between O-antigen and lipid A-core OS was elucidated reveals that it is always in the β-configuration, whereas the sugars bound to Und-PP are in the α-configuration. Together, our biochemical and in silico data argue that WaaL proteins use a common reaction mechanism and share features of metal ion-independent inverting glycosyltransferases.

Hesperetin, a citrus flavonone, protects potentially cadmium induced oxidative testicular dysfunction in rats

The present study was aimed to evaluate the protective effect of hesperetin (Hp) on cadmium (Cd) induced oxidative testicular toxicity in rats. Subcutaneous administration of Cd (3mg/kg body weight) for 21 days significantly elevated the levels of oxidative stress markers, Cd concentration in testis and lowered the levels of enzymatic, non-enzymatic antioxidants and membrane bound enzymes in the testicular tissue. Hp administrated orally along with Cd injection for 21 days, significantly revert back the status of oxidative stress markers, Cd concentration in testis, improved status of antioxidant markers and membrane bound enzymes in the testis to near normal level. The histopathological studies in the testis of rats also supported that Hp (40 mg/kg) markedly reduced the toxicity of Cd and preserved the normal histoarchitecture pattern of the testis. Thus, the results suggest that Hp acts as a potent antioxidative agent against Cd induced testicular toxicity in rats.

Involvement of thermoplasmaquinone-7 in transplasma membrane electron transport of Entamoeba histolytica trophozoites: a key molecule for future rational chemotherapeutic drug designing

The quinone composition of the transplasma membrane electron transport chain of parasitic protozoa Entamoeba histolytica was investigated. Purification of quinone from the plasma membrane of E. histolytica and its subsequent structural elucidation revealed the structure of the quinone as a methylmenaquinone-7 (thermoplasmaquinone-7), a napthoquinone. Membrane bound thermoplasmaquinone-7 can be destroyed by UV irradiation with a concomitant loss of plasma membrane electron transport activity. The abilities of different quinones to restore transplasma membrane electron transport activity in UV irradiated trophozoites were compared. The lost activity was recovered completely by the addition of thermoplasmaquinone-7, but ubiquinones are unable to restore the same. These findings clearly indicate that thermoplasmaquinone-7 acts as a lipid shuttle in the plasma membrane of the parasite to mediate electron transfer between cytosolic reductant and non permeable electron acceptors. This thermoplasmaquinone-7 differs from that of the mammalian host and can provide a novel target for future rational chemotherapeutic drug designing.

Effect of Ethanol on Branchial Adenosine Triphosphatases in Oreochromis mossambicus (Peters)

The aim of this work was to determine the toxicity of ethanol in an aquatic system by means of bioassays with Oreochromis mossambicus (Peters) as a test organism. The study revealed changes in the gill ATPase activities. The results obtained indicated that ethanol brought about a decrease in the body weight, followed by significant inhibition on total ATPase, Na(+)/K(+) ATPase, Ca(2+) ATPase and Mg(2+) ATPase activities. The studies also indicated that these can be employed as suitable biomarkers in ethanol related toxicity studies.

Active Transport of Manganese in Isolated Membranes of Escherichia coli

Accumulation of manganese was measured in subcellular membrane vesicles isolated from Escherichia coli. Accumulation of (54)Mn by vesicles in 0.5 m sucrose is stimulated by glucose and d-lactate and is inhibited by metabolic poisons such as dinitrophenol, m-chlorophenyl carbonylcyanide hydrazone, valinomycin, and nigericin. Manganese uptake by vesicles requires 10 mm calcium, which is not required for uptake of manganese by intact cells. The calcium requirement is specific and cannot be replaced by magnesium, sodium, or potassium. Strontium can replace calcium but is somewhat less effective than calcium. The uptake of manganese is via a manganese-specific system which shows saturation kinetics with manganese with a K(m) of 8 x 10(-6)m and a V(max) of 4 nmoles per min per g (wet weight) at 25 C. Magnesium and calcium do not compete for uptake. The accumulated manganese can be released from the vesicles by lipid active agents such as toluene, and can be exchanged for external manganese.

Oxidative and nitrosative stress in experimental rat liver fibrosis: Protective effect of taurine

Taurine (TAU) has protective effects on experimental liver fibrosis. The present study investigates whether benefits of TAU are mediated through attenuation of oxidative and nitrosative stresses. Liver fibrosis was induced in male Wistar rats by simultaneous administration of iron (0.5%, w/w) and ethanol (6g/kg/day) for 60 days consecutively. Significant increases in thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, protein carbonyl content and loss of non-protein, protein and total thiols were observed in the liver of iron plus alcohol-fed rats. Nitrosative stress was marked by increased levels of S-nitrosothiols and decreased nitrite content. Accumulation of nitrated and oxidatively modified proteins in liver was further evidenced by immunohistochemical localization with specific antibodies for 4-hydroxynonenol (4-HNE), 3-nitrotyrosine (3-NT) and dinitrophenol (DNP). Decrease in mitochondrial ion-transport enzymes and disturbances in calcium and iron levels were also observed in these rats. TAU administration (2% (w/v) in drinking water) significantly reduced the levels of lipid hydroperoxides, TBARS, protein carbonyl with concomitant elevation in thiol levels. The presence of 4-HNE, 3-NT and DNP-protein adducts was minimal. TAU also improved mitochondrial enzyme activities and regulated iron and calcium levels. These results show that the restorative effect of taurine in fibrosis involves amelioration of protein and lipid damage by decreasing oxidative and nitrosative stresses.

Influence of tetrahydrocurcumin on erythrocyte membrane bound enzymes and antioxidant status in experimental type 2 diabetic rats

Curcuma longa (Zingiberaceae) has been used traditionally as antidiabetic and has been proven scientifically to possess high antioxidant activity and anticancer properties. The active components of Curcuma longa such as curcumin and tetrahydrocurcumin (THC), a major colourless metabolite of curcumin also possesses antidiabetic, antiinflammatory and antioxidant activity. In the present study the effect of THC and curcumin on erythrocyte membrane bound enzymes and antioxidants activity in streptozotocin (STZ) and nicotinamide induced type 2 diabetic model was investigated. Oral administration of THC at 80 mg/kg body weight to diabetic rats for 45 days. The effect of THC and curcumin on glucose, insulin, haemoglobin, glycosylated haemoglobin, thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), glutathione peroxide (Gpx), glutathione-S-transferase (GST), reduced glutathione (GSH) and membrane bound enzymes were studied. The effect of THC was compared with curcumin. The levels of blood glucose, glycosylated haemoglobin, erythrocyte TBARS, were increased significantly whereas the level of plasma insulin and haemoglobin, erythrocyte antioxidants (SOD, CAT, GPx, GST and GSH), membrane bound total ATPase, Na(+)/K(+)-ATPase, Ca(2+)-ATPase, Mg(2+)-ATPase were decreased significantly in diabetic rats. Administration of THC and curcumin to diabetic rats showed decreased level of blood glucose, glycosylated haemoglobin and erythrocyte TBARS. In addition the levels of plasma insulin, haemoglobin, erythrocyte antioxidants and the activities of membrane bound enzymes also were increased in THC and curcumin treated diabetic rats. These biochemical observations were supplemented by histopathological examination of pancreas section. The present study indicates that the THC possesses a significant beneficial effect on erythrocyte membrane bound enzymes and antioxidants defense in addition to its antidiabetic effect.

Mineral uptake and biochemical changes in Helianthus annuus under treatment with different sodium salts

Experiments were conducted to study the effects of different sodium salts viz., sodium chloride (NaCl), sodium sulphate (Na(2)SO(4)) and sodium carbonate (Na(2)CO(3)) on growth, dry matter production, mineral contents, biochemical constituent and enzyme activities of sunflower (Helianthus annuus L.). The germinating sunflower seeds were treated with 10, 20 and 50mM NaCl and Na(2)SO(4) and 5, 10 and 15 mM Na(2)CO(3). The seedling growth, minerals, chlorophyll content and biochemicals like protein and free amino acid contents with enzyme activities like ATPase and protease were analysed on 8 DAS. The seedlings were separated into root, stem, leaf and cotyledon on 8 DAS. All the treatments decreased the germination percentage; shoot length, root length, leaf area and dry weight, chlorophyll and protein contents significantly. Potassium, sodium and free amino acid contents; activities of ATPase and protease were increased when compared to control. This effect was very high in the Na(2)CO(3) treated seedlings this was followed by Na(2)SO(4) and NaCl treated seedlings. From the results of this investigation, it is clear that, the sunflower seedlings were affected significantly in the Na(2)CO(3) treatments, and followed by Na(2)SO(4) and NaCl treatments.

Beneficial effect of succinic acid monoethyl ester on erythrocyte membrane bound enzymes and antioxidant status in streptozotocin–nicotinamide induced type 2 diabetes

Succinic acid monoethyl ester (EMS) was recently proposed as an insulinotropic agent for the treatment of non-insulin dependent diabetes mellitus. In the present study the effect of EMS and metformin on erythrocyte membrane bound enzymes and antioxidants activity in plasma and erythrocytes of streptozotocin-nicotinamide induced type 2 diabeteic model was investigated. Succinic acid monoethyl ester was administered intraperitonially for 30 days to control and diabetic rats. The effect of EMS on glucose, insulin, hemoglobin, glycosylated hemoglobin, TBARS, hydroperoxide, superoxide dismutase (SOD), catalase (CAT), glutathione peroxide (Gpx), glutathione-S-transferase (GST), vitamins C and E, reduced glutathione (GSH) and membrane bound enzymes were studied. The effect of EMS was compared with metformin, a reference drug. The levels of glucose, glycosylated hemoglobin, TBARS, hyderoperoxide, and vitamin E were increased significantly whereas the level of insulin and hemoglobin, as well as antioxidants (SOD, CAT, Gpx, GST, vitamin C and GSH) membrane bound total ATPase, Na(+)/K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase were decreased significantly in streptozotocin-nicotinamide diabetic rats. Administration of EMS to diabetic rats showed a decrease in the levels of glucose, glycosylated hemoglobin, lipid peroxidation markers and vitamin E. In addition the levels of insulin, hemoglobin, enzymic antioxidants, vitamin C, and GSH and the activities of membrane bound enzymes also were increased in EMS and metformin treated diabetic rats. The present study indicates that the EMS possesses a significant beneficial effect on erythrocyte membrane bound enzymes and antioxidants defense system in addition to its antidiabetic effect.

Cardioprotective effect of oleanolic acid on isoproterenol-induced myocardial ischemia in rats

This study was designed to investigate the protective effect of oleanolic acid (OA) against isoproterenol-induced myocardial ischemia in rat myocardium. Wistar strain rats were pretreated with OA (20, 40, and 60 mg/kg, s.c) for 7 days and then intoxicated with isoproterenol (ISO, 85 mg/kg, sc for 2 consecutive days). Heart were excised from the experimental animals and assessed for the activities of marker enzymes [alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and creatine phosphokinase (CPK)], the levels of lipid peroxide products [thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides (HP) and conjugated dienes (CD)], myeloperoxidase (MPO), lipid profiles [total cholesterol (TC), free cholesterol, ester cholesterol, triglycerides (TG), free fatty acids (FFA) and phospholipids (PL)], and membrane-bound ATPase enzymes (total ATPase, Na(+)K(+) ATPase, Ca(2 +) ATPase, and Mg(2 +) ATPase). Troponin T and I were estimated in plasma. Leakage of cardiac markers, elevated lipid peroxidation with increased lipid profiles and decreased activities of membrane-bound ATPase enzymes were confirmed the severe myocardial damage occurring as a consequence of isoproterenol-induced ischemia, and they also showed the significant improvement effected by oleanolic acid pretreatment. These findings provided evidence that oleanolic acid was found to be protecting rat myocardium against ischemic insult and the protective effect could attribute to its anti-oxidative, anti-hyperlipedemic, and anti-arrhythmic properties as well as its membrane-stabilizing action.

Microcin J25 has dual and independent mechanisms of action in Escherichia coli: RNA polymerase inhibition and increased superoxide production

Microcin J25 (MccJ25) uptake by Escherichia coli requires the outer membrane receptor FhuA and the inner membrane proteins TonB, ExbD, ExbB, and SbmA. MccJ25 appears to have two intracellular targets: (i) RNA polymerase (RNAP), which has been described in E. coli and Salmonella enterica serovars, and (ii) the respiratory chain, reported only in S. enterica serovars. In the current study, it is shown that the observed difference between the actions of microcin on the respiratory chain in E. coli and S. enterica is due to the relatively low microcin uptake via the chromosomally encoded FhuA. Higher expression by a plasmid-encoded FhuA allowed greater uptake of MccJ25 by E. coli strains and the consequent inhibition of oxygen consumption. The two mechanisms, inhibition of RNAP and oxygen consumption, are independent of each other. Further analysis revealed for the first time that MccJ25 stimulates the production of reactive oxygen species (O(2)(*-)) in bacterial cells, which could be the main reason for the damage produced on the membrane respiratory chain.

Diallyl tetrasulfide modulates the cadmium-induced impairment of membrane bound enzymes in rats

Cadmium (Cd) induces extensive membrane damage that contributes to the cytotoxic effect of Cd. We studied the effect of diallyl tetrasulfide (DTS) from garlic on Cd-induced changes in lipid peroxidation and membrane-bound enzymes in liver, kidney, and testis of rats. Cadmium exposure (3 mg/kg body weight, s.c) for 3 weeks induced a significant elevation in the levels of lipid peroxidation markers (thiobarbituric acid substances and lipid hydroperoxides) with a significant decrease in the activities of membrane bound ATPases (Na+/K+ ATPase, Ca2+ ATPase, Mg2+ ATPase), the indicators of membrane function in liver, kidney and testis. The oral administration of DTS (40 mg/kg body weight) along with Cd significantly decreased the level of lipid peroxidation and significantly restored the activities of membrane bound ATPases. The results of our study suggest that DTS attenuates lipid peroxidation in tissues and promotes the stability of the membrane by protecting it from Cd-induced alterations.

The Cu(II)-reductase NADH dehydrogenase-2 of Escherichia coli improves the bacterial growth in extreme copper concentrations and increases the resistance to the damage caused by copper and hydroperoxide

NADH dehydrogenase-2 (NDH-2) from Escherichia coli respiratory chain is a membrane-bound cupric-reductase encoded by ndh gene. Here, we report that the respiratory system of a ndh deficient strain suffered a faster inactivation than that of the parental strain in the presence of tert-butyl hydroperoxide due to endogenous copper. The inactivation was similar for both strains when copper concentration increased in the culture media. Furthermore, several ndh deficient mutants grew less well than the corresponding parental strains in media containing either high or low copper concentrations. A mutant strain complemented with ndh gene almost recovered the parental phenotype for growing in copper limitation or excess. Then, NDH-2 gives the bacteria advantages to diminish the susceptibility of the respiratory chain to damaging effects produced by copper and hydroperoxides and to survive in extreme copper conditions. These results suggest that NDH-2 contributes in the bacterial oxidative protection and in the copper homeostasis.

Counteraction of oxalate induced nitrosative stress by supplementation of l-arginine, a potent antilithic agent

BACKGROUND

Our understanding of nitrosative stress in the process of urolithiasis is far from complete. Earlier studies carried out in our laboratory demonstrate the presence of nitrated THP in stone formers, l-arginine (l-arg) a precursor of nitric oxide (NO), attenuates the endothelial dysfunction caused by reactive nitrogen species. We investigated the role of l-arg in ethylene glycol (EG)-induced urolithic rat model and observed its antilithic and antioxidative properties.

METHODS

Hyperoxaluria was induced using 0.75% EG in drinking water. l-arg [1.25 g/kg body weight] was given orally for a period of 28 days.

RESULTS

EG-treated rats showed significant loss in body weight and increase in the activities of oxalate synthesizing enzymes such as glycollic acid oxidase in liver. Lactate dehydrogenase activity in liver and kidney was increased. The activity of the free radical producing enzyme xanthine oxidase, tissue oxalate and calcium levels were significantly increased in EG-treated rats. Depletion in the antioxidant enzymes, membrane bound ATPases and thiol status was observed in these rats. l-arg co-supplementation to EG-treated rats maintained the activities of the oxalate synthesizing enzymes and free radical producing enzymes with in the normal range. Tissue oxalate and calcium levels were also maintained near normal in l-arg treated hyperoxaluric rats. l-arg, by its cytoprotective effect, maintained the thiol status, thereby preserving the activities of the membrane bound ATPases and preventing proteinuria and subsequent weight loss in EG-treated rats.

CONCLUSION

l-arg feeding prevents the retention of calcium oxalate crystals in hyperoxaluric rats by way of protecting the renal cells from oxidative injury and also by providing a second line of defense through the normalization of the oxalate metabolism. It reduces the risk of stone formation, by curtailing free radicals and hyperoxaluria as both of them have to work in close association to form stones.

Engineering the metabolism of Escherichia coli W3110 for the conversion of sugar to redox-neutral and oxidized products: homoacetate production

Microbial processes for commodity chemicals have focused on reduced products and anaerobic conditions where substrate loss to cell mass and CO(2) are minimal and product yields are high. To facilitate expansion into more oxidized chemicals, Escherichia coli W3110 was genetically engineered for acetate production by using an approach that combines attributes of fermentative and oxidative metabolism (rapid growth, external electron acceptor) into a single biocatalyst. The resulting strain (TC36) converted 333 mM glucose into 572 mM acetate, a product of equivalent oxidation state, in 18 h. With excess glucose, a maximum of 878 mM acetate was produced. Strain TC36 was constructed by sequentially assembling deletions that inactivated oxidative phosphorylation (deltaatpFH), disrupted the cyclic function of the tricarboxylic acid pathway (deltasucA), and eliminated native fermentation pathways (deltafocA-pflB deltafrdBC deltaldhA deltaadhE). These mutations minimized the loss of substrate carbon and the oxygen requirement for redox balance. Although TC36 produces only four ATPs per glucose, this strain grows well in mineral salts medium and has no auxotrophic requirement. Glycolytic flux in TC36 (0.3 micromol.min(-1).mg(-1) protein) was twice that of the parent. Higher flux was attributed to a deletion of membrane-coupling subunits in (F(1)F(0))H(+)-ATP synthase that inactivated ATP synthesis while retaining cytoplasmic F(1)-ATPase activity. The effectiveness of this deletion in stimulating flux provides further evidence for the importance of ATP supply and demand in the regulation of central metabolism. Derivatives of TC36 may prove useful for the commercial production of a variety of commodity chemicals.