Evaluation of glutathione s‐transferase as toxicity indicator for roxarsone and arsanilic acid in Eisenia fetida

Different compounds can induce stress response by targeting specific genes. Studies related to elucidating the detoxification and adaptive responses of proteins like glutathione‐s‐transferase (GST) can be helpful in better understanding toxicity. Roxarsone and arsanilic acid, which have been exhaustively used as animal and poultry feed additives, pose a threat to the environment and human health. GST enzyme bioassay revealed fluctuations in response to different concentrations of roxarsone and arsanilic acid at different time intervals. The highest GST enzyme activity (40.51%) was observed on day 15 of treatment with roxarsone. On the other hand, arsanilic acid caused the maximum enzyme activity (52.11%) on day 10 of treatment. During this study, the full‐length gene sequence of GST, having the size 984 bp (Genbankno. HQ693699), was achieved from Eisenia fetida and established as a biomarker to assess the toxicity of roxarsone and arsanilic acid. The deduced protein has a computed molecular mass of 23.56 kDa and a predicted isoelectric point of 9.92. Quantitative real‐time PCR revealed significant differential gene expression in response to roxarsone and arsanilic acid treatment as compared with control treatment. Roxarsone caused the highest gene expression of 7.0‐fold increase over control on day 15 of treatment, whereas arsanilic acid resulted in the highest gene expression reaching to 14.56‐fold as compared with control. This study is helpful in understanding the role of GST as a potential biomarker for chemicals like roxarsone and arsanilic acid, which can pollute the food chain. Copyright © 2012 John Wiley & Sons, Ltd.     

Partial disinhibition is required for transition of stimulus-induced sharp wave-ripple complexes into recurrent epileptiform discharges in rat hippocampal slices

Sharp wave-ripple complexes (SPW-Rs) in the intact rodent hippocampus are characterized by slow field potential transients superimposed by close to 200-Hz ripple oscillations. Similar events have been recorded in hippocampal slices where SPW-Rs occur spontaneously or can be induced by repeated application of high-frequency stimulation, a standard protocol for induction of long-lasting long-term potentiation. Such stimulation is reminiscent of protocols used to induce kindling epilepsy and ripple oscillations may be predictive of the epileptogenic zone in temporal lobe epilepsy. In the present study, we investigated the relation between recurrent epileptiform discharges (REDs) and SPW-Rs by studying effects of partial removal of inhibition. In particular, we compared the effects of nicotine, low-dose bicuculline methiodide (BMI), and elevated extracellular potassium concentration ([K(+)](o)) on induced SPW-Rs. We show that nicotine dose-dependently transformed SPW-Rs into REDs. This transition was associated with reduced inhibitory conductance in CA3 pyramidal cells. Similar results were obtained from slices where the GABAergic conductance was reduced by application of low concentrations of BMI (1-2 μM). In contrast, sharp waves were diminished by phenobarbital. Elevating [K(+)](o) from 3 to 8.5 mM did not transform SPW-Rs into REDs but significantly increased their incidence and amplitude. Under these conditions, the equilibrium potential for inhibition was shifted in depolarizing direction, whereas inhibitory conductance was significantly increased. Interestingly, the propensity of elevated [K(+)](o) to induce seizure-like events was reduced in slices where SPW-Rs had been induced. In conclusion, recruitment of inhibitory cells during SPW-Rs may serve as a mechanism by which hyperexcitation and eventually seizure generation might be prevented.     

Monoamines block kainate‐ and carbachol‐induced γ‐oscillations but augment stimulus‐induced γ‐oscillations in rat hippocampus in vitro

Monoamines are implicated in a cognitive processes in a variety of brain regions, including the hippocampal formation, where storage and retrieval of information are facilitated by synchronous network activities. We have investigated the effects of norepinephrine, serotonin, and dopamine on carbachol‐, kainate‐, and stimulus‐induced hippocampal γ‐oscillations employing combined extra‐ and intracellular recordings. Monoamines dose‐dependently and reversibly suppressed kainate‐ and carbachol‐induced γ‐oscillations while increasing the frequency. The effect of serotonin was mimicked by fenfluramine, which releases serotonin from presynaptic terminals. Forskolin also suppressed kainate‐ and carbachol‐induced γ‐oscillations. This effect was mimicked by 8‐Br‐cAMP and isoproterenol, an agonist of noradrenergic β‐receptor suggesting that the monoamines‐mediated suppression of these oscillations could involve intracellular cyclic adenosine 3′,5′‐cyclic monophosphate (AMP). By contrast, stimulus‐induced γ‐oscillations were dose‐dependently augmented in power and duration after monoamines application. Intracellular recordings from pyramidal cells revealed that monoamines prolonged the stimulus‐induced depolarization and membrane potential oscillations. Stimulus‐induced γ‐oscillations were also suppressed by isoproterenol, the D1 agonist SKF‐38393 forskolin, and 8‐Br‐cAMP. This suggests that the augmentation of stimulus‐induced γ‐oscillations by monoamines involves—at least in part—different classes of cells than in case of carbachol‐ and kainate‐induced γ‐oscillations. © 2009 Wiley‐Liss, Inc.     

Mechanisms of oxidative stress-induced increase in salt sensitivity and development of hypertension in Sprague-Dawley rats

High salt intake produces vascular changes that contribute to the development of hypertension in salt-sensitive individuals. Because reactive oxygen species play a role in the pathogenesis of cardiovascular diseases, we investigated whether oxidative stress contributes to salt-sensitive hypertension. Sprague-Dawley rats were divided in different groups and received tap water (vehicle), 30 mmol/L of l-buthionine sulfoximine ([BSO] an oxidant), high salt ([HS] 1% NaCl), and BSO plus HS without and with antioxidant tempol (1 mmol/L) in drinking water for 12 days. Compared with vehicle, BSO treatment caused oxidative stress and mild increase in blood pressure. Thoracic aortic rings from BSO-treated rats exhibited decreased response to endothelium-independent vasorelaxants. In HS-treated rats, the response to vasoactive agents, as well as blood pressure, was unaffected. Concomitant treatment of rats with BSO and HS produced a marked increase in blood pressure and a decreased response to both endothelium-dependent and endothelium-independent vasorelaxants with an increase in EC(50). Incubation of aortic tissue from BSO-treated rats with sodium nitroprusside showed decreased cGMP accumulation, whereas HS rats had decreased basal NO synthase activity. Tempol decreased oxidative stress, normalized blood pressure, and restored NO signaling and responses to vasoactive compounds in BSO and BSO plus HS rats. We conclude that BSO increases oxidative stress and reduces NO signaling, whereas HS reduces NO levels by decreasing the NO synthase activity. These phenomena collectively result in reduced responsiveness to both endothelium -dependent and endothelium- independent vasorelaxants and may contribute to salt-sensitive hypertension.     

The role of salivary cytokine biomarkers in tongue cancer invasion and mortality

Squamous cell carcinoma of the tongue (TSCC) has one of the poorest prognoses of head and neck cancers. This study aims to improve early detection of the disease by identifying salivary biomarkers that can identify a spectrum of patients progressing from high-risk to TSCC. We also examine the mortality of exophytic and endophytic TSCC, expecting the elevated cytokine levels in endophytic patients to be associated with a shorter survival. Saliva was collected from patients with TSCC and controls and cytokine protein levels were measured. Specimens were collected from the Los Angeles County (LAC) + University of Southern California (USC) and USC University Hospital clinics. A convenience sample of patients with TSCC was divided into endophytic (n=10) and exophytic (n=8) cancer by physician diagnosis. Controls were divided into 4 groups of 14 based on their high-risk smoking and drinking behaviors. Main outcome measures: The levels of IL-1α, IL-6, IL-8, VEGF-a and TNF-α in saliva were measured using quantitative ELISA and compared using two-way ANOVA. All five cytokines were elevated in the endophytic TSCC group compared to other groups, which correlated with the decreased survival rate (10.4 months) in this group compared to exophytic TSCC (24 months). IL-1α, IL-6, TNF-α and VEGF were also elevated in the exophytic TSCC group compared to smoking-drinking controls. Salivary levels of IL-1α, IL-6, IL-8, VEGF-a and TNF-α can identify the progression of TSCC from high-risk to neoplasm, serving as potential biomarkers for cancer screening and early detection. The correlation with survival implies a prognostic benefit and could serve as a tool for management decisions and future treatment targets.     

Familial dysbetalipoproteinemia: a potentially fatal disorder

Familial dysbetalipoproteinemia is an inherited disorder in which both cholesterol and triglycerides are elevated in the plasma of the blood, which pre-disposes people to coronary artery disease and peripheral vascular disease. We report two young boys with multiple cutaneous xanthomas and grossly abnormal serum cholesterol and triglycerides. Two of the family members had died of cardiovascular accidents in young age and rest of the family members had deranged lipid profile. Patients were managed with lipid lowering drugs and fat restriction diet. All family members were counseled and advised regular exercise and follow-up.     

Should surgical pleurectomy for spontaneous pneumothorax be always thoracoscopic?

Fifty-seven patients were studied over a period of three years to analyse the efficacy of surgical pleurectomy for spontaneous pneumothorax. Thirty-one and 26 patients underwent open and video-assisted thoracoscopic surgery (VATS) pleurectomy, respectively. VATS was the main modality used for primary spontaneous pneumothorax (PSP) (21 vs. 8). However, secondary spontaneous pneumothorax (SSP) was mainly managed with open pleurectomy (23 vs. 5). The median operating time was significantly longer in open group (72.4 vs. 55 min; P=0.005). The amount of analgesia required in the first five days was significantly more in open group (108 mg vs. 46.9 mg; P=0.02). Chest drainage was significantly more in open group (1027.1 ml vs. 652.8 ml; P=0.04). However, chest drain duration and hospital stay had no significant difference. VATS emerged as a cost-effective modality (1770 pounds vs. 3226 pounds). The ability to return to work was significantly earlier in VATS group in PSP patients (6 weeks vs. 10 weeks; P=0.007). There were 3 (5.27%) recurrences in VATS group for patients with SSP. This experience suggests that VATS pleurectomy is an appropriate modality for PSP. However, open pleurectomy is a viable alternative to treat SSP.