Biochemical evidence on the potential role of methyl mercury in hepatic glucose metabolism through inflammatory signaling and free radical pathways

Methylmercury (MeHg) is an extremely important environmental toxicant posing serious health risks to human health and a big source of environmental pollutant. Numerous evidence available showing a link between nervous system toxicity and MeHg exposure. Other forms of mercury are reason of metabolic toxic effects and alteration of DNA in the human body. The sources of exposure could be occupational or other environmental settings. In the present study MeHg was orally gavaged to mice, at doses of 2.5, 5, and 10 mg/kg for 4 weeks. Fasting hyperglycemia, activity of hepatic phoshphoenolpyruvate carboxykinase and glucose 6-phoshphate were reported high as compared to control group. Inflammatory markers like, tumor necrosis factor α, the actual end product of inflammatory mediators’ cascade pathway was also raised in comparison to control group. Hyperinsulinemia observed in serum showed clear understanding of mercury induced insulin resistance. Moreover, tissue damage due to increased oxidative stress markers like, hepatic lipid peroxidation, 8-deoxygunosine, reactive oxygen species, and carbonyl groups was significantly higher as compared to control group. MeHg caused a significant reduction in antioxidant markers like ferric reducing antioxidant power and total thiol molecules. The present study highlighted that activity of key enzymes involved in glucose metabolism is changed, owing to MeHg induced toxicity in the liver. Induction of similar toxic effects assumed to be stimulated by the production of high quantity free radicals.     

Relationship between blood pressure,sleep K-complexes,and muscle sympathetic nerve activity in humans

Stage 2 sleep is characterized by the EEG appearance of "K-complexes" and blood pressure oscillations. K-complexes may be directly related to blood pressure changes or they may reflect central sympathetic activation. We analyzed the temporal relationship among K-complexes, heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) during sleep in eight healthy volunteers (3 men and 5 women, age 22-41 yr). Most K-complexes presented as single large complexes (56 +/- 20%), followed by single small complexes (15 +/- 14%) and as couplets or triplets (13 +/- 6%). Single large K-complexes were preceded by a baroreflex-mediated increase of MSNA in approximately one-half (55%) of the cases. Detailed analysis of HR, BP, and MSNA was possible in 63 (45%) large single K-complexes not disturbed by preceding baroreflex-related changes. Systolic and diastolic BP and MSNA increased significantly after single events (22.5 +/- 13, 5.2 +/- 2.1, and 6.5 +/- 3.0%). Mean sympathetic baroreflex latency was similar after the single large K-complexes compared with the mean value during stage 2 sleep (1,290 +/- 126 vs. 1,279 +/- 61 ms). The area under the burst was significantly increased after single large K-complexes (median 3.9 vs. 9.0 arbitrary units, P < 0.03). The results support the hypothesis that K-complexes express cortical activation leading to temporary facilitation of sympathetic outflow in a graded fashion. Their functional effects appear to be independent of baroreflex modulation of MSNA in approximately 50% of the cases.     

Fish entrapment in the seawater intake of a power plant at Karachi coast

Synopsis The study deals with the entrapment of fishes in the intake of Karachi Nuclear Power Plant. A total of 62 species of marine fishes belonging to 43 genera were observed entrapped in the seawater intake. Therapon puta, Liza waigiensis, Abudefduf septemfasciatus, and Lagoceptalus inermis were the most common. Mass mortalities of the juveniles of Sardinella sindensis were recorded in September and October of 1974, 1975, and 1977. Commercially important fishes such as sardines, mullets and anchovies, were entrapped in the intake of the power plant in considerable numbers at various times of the year. The majority of fishes removed from the screen washes of the power plants were killed by impingement.     

Modulation of free radical stress in human red blood cell membrane by forskolin and the prospects for treatment of cardiovascular disease and diabetes.

This study has examined the effect of oxidants and elevated levels of glucose on membrane lipid peroxidation of human red blood calls (RBC). Washed RBC incubated with varying concentrations of glucose at 37 degrees C for 24 hrs. showed a significant increased membrane lipid peroxidation when compared with control RBC. Addition of ferrous sulphate and ascorbic acid which are known oxidants caused greater rise in lipid peroxides compared to elevated level of glucose alone. Pre-treatment of RBC with varying doses of forskolin (4-70 microg) was associated with significantly smaller rise in lipid peroxides in a dose dependent manner. Forskolin effect was comparable with the antioxidant effect of other drugs such as vitamin E, trimetazidine, ginkocer, probucol. It is possible that forskolin at higher concentrations may have a greater antioxidant effect than other antioxidant drug. However more studies, especially animal experiments, and trials in human would be necessary to confirm our findings.     

Self-assembly of cationic surfactants on the carbon nanotube surface: insights from molecular dynamics simulations

The insolubility of carbon nanotubes (CNTs) in aqueous media has been a limitation for the practical application of this unique material. Recent studies have demonstrated that the suspend ability of CNT can be substantially improved by employing appropriate surfactants. Although various surfactants have been tested, the exact mechanism by which carbon nanotubes and the different surfactants interact is not fully understood. To deepen the understanding of molecular interaction between CNT and surfactants, as well as to investigate the influence of the surfactant tail length on the adsorption process, we report here the first detailed large-scale all-atomistic molecular dynamics simulation study of the adsorption and morphology of aggregates of the cationic surfactants containing trimethylammonium headgroups (C₁₂TAB and C₁₆TAB) on single-walled carbon nanotube (SWNT) surfaces. We find that the aggregation morphology of both C₁₂TAB and C₁₆TAB on the SWNT is dependent upon the number of the surfactants in the simulation box. As the number of the surfactants increases the random monolayer structure gradually changes to the cylinder-like monolayer structure. Moreover, we make a comparison between the C₁₂TAB and C₁₆TAB adsorption onto SWNTs to clarify the role of the surfactant tail length on the adsorption process. This comparison indicates that by increasing the number of surfactant molecules, the larger number of the C₁₆TAB molecules tend to adsorb onto SWNTs. Further, our results show that a longer chain yields the higher packed aggregates in which the surfactant heads are extended far into the aqueous phase, which in turn may increase the SWNTs stabilization in aqueous suspensions.