Oxalate-mediated oxidant–antioxidant imbalance in erythrocytes: role of N-acetylcysteine

The present in-vivo study was to observe the effect of N-acetylcysteine (NAC) on oxalate-induced oxidative stress on rat erythrocytes. A total of 15 Wistar rats were divided into three groups. The control group received normal saline by single intraperitoneal injection. Hyperoxaluria was induced by single intraperitoneal (i.p.) dose of sodium oxalate (70 mg/kg body weight in 0.5 mL saline) to a second group. The third group was administered single i.p. dose of NAC according to 200 mg/kg body weight dissolved in 0.5 mL saline, half an hour after oxalate dose. NAC administration normalized antioxidant enzyme activities (superoxide dismutase and catalase) and reduced malondialdehyde content (indicator of lipid peroxidation) in hyperoxaluric rat’s red blood cell (RBC) lysate. NAC administration also resulted in a significant improvement of thiol content in RBC lysate via increasing reduced glutathione content and maintaining its redox status. Oxalate-caused alteration of cholesterol/phospholipid ratio (determining membrane fluidity) was also rebalanced by NAC administration. Further, after NAC administration, electron microscopy showed improved cell morphology presenting its prophylactic properties. Above results indicate that NAC treatment is associated with an increase in plasma antioxidant capacity and a reduction in the susceptibility of erythrocyte membranes to oxidation. Thus, the study presents positive pharmacological implications of NAC against oxalate-mediated impairment of erythrocytes.

Treatment of angiolymphoid hyperplasia with eosinophilia with the carbon dioxide laser

Angiolymphoid hyperplasia with eosinophilia (ALHE) is an uncommon, idiopathic condition that presents with isolated or grouped plaques or nodules in the periauricular region, forehead, or scalp. ALHE is marked by a proliferation of blood vessels with distinctive large endothelial cells accompanied by a characteristic inflammatory infiltrate that includes eosinophils. The lesion is benign but may be persistent and difficult to eradicate. Various therapeutic modalities that have been tried for its treatment include intralesional and oral corticosteroids, cryotherapy, oral retinoids, vinblastine, surgical excision, laser therapy, and INFalpha2a. We report two cases with this rare condition: one patient, treated with cryotherapy, did not improve, while the second patient was successfully treated with the CO(2) laser.

Reversal of Hyperoxaluria-Induced Alteration in Rat Liver by Administration ofN-Acetylcysteine

The current work was designed to study the potential of N-acetylcysteine (NAC) in modulating hyperoxaluric manifestations induced by acute oxalate dose in rat liver. Hyperoxaluric conditions were induced by giving a single dose of sodium oxalate (70 mg/kg body weight) in one group, and in the other group, hyperoxaluric rats were administered NAC (200 mg/kg body weight) after 30 min of the oxalate dose. After 12 h of the above treatment, blood was taken from the orbital sinus for testing serum oxalate, and animals were sacrificed. To exploit the potential of NAC, various oxidative stress parameters [lipid peroxidation (LP) and activity of antioxidant enzymes], lipid content, and histologic analysis of rat liver were performed. The increased level of LP and activities of superoxide dismutase and catalase in hyperoxaluric rats were restored after NAC treatment. Not only the decreased amount of total lipids and phospholipids but also the increased ratio of cholesterol/phospholipid (showing decreased membrane fluidity) in hyperoxaluric rats were balanced by NAC treatment. Further restored histologic changes of liver tissue confirmed the protective antioxidant effects of the given drug. Thus, N-acetylcysteine being an extraneous antioxidant showed curative properties toward hyperoxaluric manifestations in liver.

Changes in antioxidant defense status in response to cisplatin and 5-FU in esophageal carcinoma

The ability of reactive oxygen species to induce cellular damage and to cause cell death opens the possibility of exploiting this property in the treatment of esophageal cancer through a free radical mediated mechanism. The present study was carried out with the aim of evaluating the changes in the antioxidant defense status in esophageal cancer patients treated without and with neoadjuvant therapy (NAT). Forty surgically resected tissue specimens from tumors, tissue adjoining the tumors and paired macroscopically normal mucosa were obtained from esophageal cancer patients treated with or without chemo-radiotherapy. An evaluation of antioxidant defense system in the normal, adjoining and tumor esophageal tissues in response to NAT revealed decreased catalase activity in tumor and adjoining tissues as compared to their respective normal tissue levels. Similarly, decreased superoxide dismutase activity was observed in tumor tissue in response to NAT. In both the treatment groups (with and without NAT), no significant change was observed in the enzyme activity of glutathione reductase in the normal, adjoining and tumor tissues. Enhanced glutathione peroxidase activity was found in tumor tissue, as compared to the adjoining and paired normal tissue of patients after NAT. Estimation of reduced glutathione (GSH) levels showed a significant decline in GSH levels in esophageal tumors after NAT. Depletion of GSH, an endogenous antioxidant, would elevate drug sensitivity and might predispose neoplastic cells to apoptosis in response to NAT. The antioxidant enzymes in the esophageal carcinoma thus may play an important role in influencing the final outcome upon NAT course.

Post-radiation pulmonary epithelial regeneration from transplanted adult stem cells

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Background: Pneumonitis and pulmonary damage are common toxicities of chest radiation therapy (RT), which may be reduced by transplantation of stem cells that differentiate into pulmonary epithelium. Multipotent Adult Progenitor Cells (MAPC) are adult bone marrow (BM) derived cells, which after IV injection in NOD-SCID mice, differentiate into epithelial and hematopoietic tissues (Nature 418:41). Here we tested the ability of mouse (m) MAPC to regenerate epithelia after RT, in Fanconi Anemia C (FAC) mouse model, which inherently has DNA repair defects and is over sensitive to DNA-cross linking agents. Methods: One million, enhanced-green fluorescent protein (eGFP)- expressing, wild-type mMAPC were injected IV in FAC mice, 4–24 hours after 7.5 Gy (followed by mitomycin C {MMC} 0.1mg/kg/week X 4 in a subset) or 11 Gy RT. Non-eGFP expressing BM was co-transplanted after myeloablative (11 Gy) RT. BM, lungs, intestine and liver of the recipients were analyzed 3–10 months post-transplant for eGFP+ cells and epithelial (CK+) or hematopoietic (CD45+) differentiation using flowcytometry (BM) & immunohistochemistry. Control FAC mice were identically treated but without MAPC. Results: MAPC engraftment (>1% eGFP+ cells) was absent in all control mice. Following 7.5 Gy RT, autologous BM recovery occurred in all (N=10) mice and 1 mouse had 2.7% donor-derived hematopoietic (eGFP+/CD45+) cells after MMC. In both recipients of 11Gy RT, analyzed 9–10 months post-transplant, 5–7% of all CD45+ BM cells were donor MAPC-derived. No donor MAPC-derived epithelial cells were seen in the intestine or liver. However, lungs of most recipients had clusters of donor MAPC-derived epithelial cells, estimated to comprise 1–8% of all pulmonary epithelial cells, consistent with homing of MAPC in lungs following IV injection and their epithelial differentiation in the post-radiation, regenerative, pulmonary micro- environment. The highest degree of MAPC-derived pulmonary regeneration was seen following 11Gy RT that was persistent at 10 months post- transplant. Conclusions: Following radiation, IV injected mMAPC differentiate into hematopoietic and pulmonary epithelial cells that persist long-term. MAPC transplantation has the potential for reducing radiation-induced pulmonary toxicity.

No significant financial relationships to disclose.

Selenium enrichment and anti-oxidant status in baker's yeast, saccharomyces cerevisiae at different sodium selenite concentrations

The use of selenized yeast as enriched selenium supplements in human nutrition has become a topic of increasing interest over the last decade. The present study was designed with the aim to achieve a balance between selenium (Se) incorporation and optimal growth of yeast cells along with effect of Se enrichment on antioxidant defense status of yeast cells. Since oxidative stress has been known to play a role in the life span of all types of cells, so in the present studies anti-oxidant defense status was evaluated in the Se- enriched baker's yeast cell culture model. Upon Se supplementation as sodium selenite at various concentrations in the growth medium, a continuous increase in glutathione peroxidase (GSH-Px) activity and Se content was observed. In case of reduced glutathione (GSH) decreasing trend were observed with increasing Se concentrations. An increasing trend in total glutathione as well as glutathione-s-transferase activity was observed at increasing Se concentrations. Thus, Se supplementation significantly enhanced GSH-Px levels along with alterations in other anti-oxidant enzymes, suggesting the role of Se in the enzyme defense system of yeast against oxidative damage. Further, as Se exerts growth inhibitory effect on cells, the growth inhibition study was carried out and decrease in biomass was observed with increasing concentrations of Se. Due to nutritional benefits, Se-enriched yeast may be considered a safe source of Se supplementation.

Obesity, breast cancer and the role of adipocytokines

Obesity is a worldwide problem which impacts the risk and prognosis of some of the more common forms of cancer, including breast cancer in post-menopausal women. As the basis for understanding the potential mechanisms of obesity and cancer relationship has advanced, a number of new hypotheses have emerged. The adipocytokines are a complex group of biologically active polypeptides. Leptin is a growth hormone, secreted by adipose tissue, whose levels are normally elevated in obese individuals and may have a promoting effect on carcinogenesis and metastasis of breast cancer, possibly in an autocrine manner. Leptin interferes with the insulin signaling pathway and in type 2 diabetes plasma leptin levels are found to be correlated with the degree of insulin resistance, a relationship independent of body mass. This relationship might provide a mechanistic explanation for promotion potential.

The cGMP-binding, cGMP-specific phosphodiesterase (PDE5): intestinal cell expression, regulation and role in fluid secretion

The expression and regulation of the cGMP-binding, cGMP-specific phosphodiesterase, PDE5, was studied in intestinal cells. Both PDE5A1 and PDE5A2 splice forms were cloned from the cDNA prepared from human colonic T84 cells, and PDE5 activity was dependent on increases in intracellular cGMP levels which correlated with increased phosphorylation of the enzyme. PDE5 expression was monitored in different regions of the gastrointestinal tract and nearly 50% of the phosphodiesterase activity in the duodenum, jejunum, ileum and colon was inhibited by sildenafil citrate. Administration of the stable toxin to intestinal loops resulted in activation of PDE5. Inhibition of PDE5 by sildenafil citrate led to fluid accumulation in loops, suggesting a possible explanation for the side effect of diarrhoea observed in individuals administered sildenafil citrate. Our results therefore represent the first study on the expression and regulation of PDE5 in intestinal tissue, and indicate that mechanisms to control its activity may have important consequences in intestinal physiology.

A correlation between membrane cholesterol level, cell adhesion and tumourigenicity of polyoma virus transformed cells

We have investigated the implications of the rise in membrane cholesterol levels on several in vitro and in vivo properties of polyoma virus transformed rat fibroblasts (PyF), with a special emphasis on alpha5beta1 integrin functions. We show that increased membrane cholesterol causes the PyF cells to change their shape and become more bipolar in appearance. These cells also show significantly higher adhesion to the cell-binding domain of fibronectin, increased localization of alpha5beta1 integrin and talin molecules in focal adhesions and a more robust actin cytoskeleton organization. PyF cells with increased membrane cholesterol show reduced growth in vitro and tumours caused by these cells in nude mice are slow growing. These changes in the growth properties of PyF cells are reversible when the cholesterol levels of PyF cells become normal. Our results suggest that changes in membrane cholesterol levels influence the growth and morphological properties of transformed cells, which can be exploited in controlling the growth of tumours in vivo.

Modulation of gut physiology through enteric toxins

Diarrheal diseases caused by microorganisms and their toxins are a major cause of mortality and morbidity throughout the world. Acute diarrhea is mainly caused due to increased intestinal secretion, commonly as a result of infection with enterotoxin producing organisms (enterotoxigenic Escherichia coli, Vibrio cholera) or due to decreased intestinal absorption from infection with organisms that damage the intestinal epithelium (enteropathogenic E. coli sp., Shigella sp., Salmonella sp.) The studies of the impact of enteric pathogens and their virulence factors exert their effect by producing toxins, called bacterial toxins. The protein toxins are produced by diverse group of bacteria. Most of the bacterial toxins exert their effect through involvement of ADP-ribosylation proteins; otherwise essential for several cellular functions while other toxins involve guanylate cyclase systems or calcium and protein kinases for their ultimate action.

Hemifacial microsomia. A case report and review

Hemifacial microsomia (HFM) is a variable asymmetric craniofacial malformation resulting in hypoplasia of the components of the first and second branchial arches. Because of the extremely variable expressively of the HFM, treatment measures also vary considerably from the use of activator to total reconstruction of TM joint and management of secondary deformities of maxilla, nose, orbit and zygomatic bone. We present a case of HFM type I of mild deformity treated with onlay bone grafting.

Comparison of GSTM polymorphisms and risk for oral cancer between African-Americans and Caucasians

Two members of the mu class of glutathione S-transferase (GST) genes, GSTM1 and GSTM3, have polymorphic alleles which have been associated with altered levels of GST mu protein expression and may be linked to increased risk for several tobacco-related cancers. Oral cancer is a tobacco-related disease that affects African-American men at a significantly higher incidence than Caucasian men. To examine the potential role of GSTM polymorphisms in risk for oral cancer in African-Americans and Caucasians, the prevalences of the GSTM1 null and GSTM3 intron 6 polymorphisms were examined in 63 African-American and 101 Caucasian patients with histologically confirmed primary oral cancer, as well as in 133 African-American and 213 Caucasian matched control subjects. In African-Americans, the odds ratio for oral cancer associated with the GSTM1 (0/0) genotype was 3.1 [95% confidence interval (CI) = 1.1-8.5], with the association between the GSTM1 (0/0) genotype and oral cancer risk strongest in heavy smokers [i.e. > 24 pack-years; odds ratio (OR) = 5.4, 95% CI = 1.2-24]. Using the potentially most protective GSTM1 [+]/GSTM3 (B/B) genotype as the reference group, increased risk for oral cancer was observed in African-Americans with the GSTM1 [+]/GSTM3 [(A/A) + (A/B)] (OR = 2.2, 95% CI = 0.82-6.0), GSTM1 (0/0)/GSTM3 (B/B) (OR = 4.3, 95% CI = 1.1-16), and GSTM1 (0/0)/GSTM3 [(A/A) + (A/B)] (OR = 6.6, 95% CI = 1.2-38) genotypes (P < 0.01, trend test). No significant associations were observed between GSTM genotype and oral cancer risk in Caucasians. These results suggest that the GSTM1 null and GSTM3 intron 6 polymorphisms play an important role in risk for oral cancer among African-Americans and implicates the mu class of GSTs as important tobacco carcinogen detoxifying enzymes in this population.

Association between glutathione S-transferase pi genetic polymorphisms and oral cancer risk

Polymorphisms in the gene encoding the glutathione S-transferase (GST) pi metabolizing enzyme have previously been associated with susceptibility to various cancers. In this study, the importance of GSTP1 genotypes as determinants of risk for oral cancer was assessed by examining the prevalence of GSTP1 alleles in 157 incident oral cancer cases and 260 non-cancer control individuals frequency-matched by race, sex, and age at diagnosis (+/- 5 years). The GSTP1*A, GSTP1*B, GSTP1*C, and GSTP1*D alleles were elucidated by polymerase chain reaction-restriction fragment length polymorphism analysis of polymorphisms present in codons 105 (isoleucine:valine) and 114 (alanine:valine) of the GSTP1 gene. Increased risk for oral cancer was observed in individuals who were homozygous for any combination of GSTP1 polymorphic alleles (i.e. *B, *C, and/or *D alleles; odds ratio = 2.4, 95% confidence interval = 1.2-4.8). Similar risk was observed in both Caucasians (odds ratio = 2.6, 95% confidence interval = 1.1-6.2) and African-Americans (odds ratio = 2.3, 95% CI = 0.68-7.5). A greater risk was observed in individuals with the GSTP1 (Var/Var) genotype who were exposed to low levels of smoking (i.e. < or = 20 pack-years [py], odds ratio = 3.4, 95% confidence interval = 1.1-11) than among heavier smokers (i.e. > 20 pack-years [py], odds ratio = 1.4, 95% confidence interval = 0.48-4.0). These results suggest that GSTP1 genotype may play a role in risk for oral cancer particularly among lighter smokers.