Speciation of arsenic in sulfidic waters

Formation constants for thioarsenite species have been determined in dilute solutions at 25°C, ΣH(2)S from 10(-7.5 )to 10(-3.0 )M, ΣAs from 10(-5.6 )to 10(-4.8 )M, and pH 7 and 10. The principal inorganic arsenic species in anoxic aquatic systems are arsenite, As(OH)(3)(0), and a mononuclear thioarsenite with an S/As ratio of 3:1. Thioarsenic species with S/As ratios of 1 : 1,2 : 1, and 4 : 1 are lesser components in sulfidic solutions that might be encountered in natural aquatic environments. Thioarsenites dominate arsenic speciation at sulfide concentrations > 10(-4.3 )M at neutral pH. Conversion from neutral As(OH)(3)(0 )to anionic thioarsenite species may regulate the transport and fate of arsenic in sulfate-reducing environments by governing sorption and mineral precipitation reactions

Kidney transplantation in childhood: mental health and quality of life of children and caregivers

Our objective was to assess the mental health and health-related quality of life (HRQOL) in children and their parents after renal transplantation (TX) compared to healthy controls and children with acute lymphoblastic leukemia (ALL) and to identify possible health status variables associated with impaired mental health and HRQOL. Thirty-eight TX children with a median age of 13 (range 3–19) years were investigated. Mental health was assessed by the Pediatric Quality of Life Inventory (PedsQL) 4.0 Generic Core Scales and the Strength and Difficulties Questionnaire (SDQ-20). Each mother’s own mental health and QOL were assessed by the General Health Questionnaire (GHQ-30) and the Quality of Life Scale (QOLS). Forty children with ALL [median age 11 (8.5–15.4) years] and 42 healthy children [median age 11 (8.9– 15) years] served as controls. Treadmill exercise results from 22 of the 38 patients were included in the analysis. TX children showed significantly higher levels of mental health problems and lower HRQOL at 2 to 16 years after transplantation compared to both control groups. Body mass index and maximal oxygen uptake (n = 22/38) were significant predictors of child mental health (SDQ) and child QOL (PedsQL), respectively. Based on these results, we suggest that rehabilitation after TX should include a focus on physical activity and QOL to reduce interconnected physical and psychological morbidity in kidney TX children

Epidemiologic and clinical updates on impulse control disorders: a critical review

The article reviews the current knowledge about the impulse control disorders (ICDs) with specific emphasis on epidemiological and pharmacological advances. In addition to the traditional ICDs present in the DSM-IV—pathological gambling, trichotillomania, kleptomania, pyromania and intermittent explosive disorder—a brief description of the new proposed ICDs—compulsive–impulsive (C–I) Internet usage disorder, C–I sexual behaviors, C–I skin picking and C–I shopping—is provided. Specifically, the article summarizes the phenomenology, epidemiology and comorbidity of the ICDs. Particular attention is paid to the relationship between ICDs and obsessive–compulsive disorder (OCD). Finally, current pharmacological options for treating ICDs are presented and discussed

Spontaneous Oscillations in Cytoplasmic Calcium-Concentration in Vascular Smooth-Muscle

Fluorescence measurement of fura-2 and quin2 signals from confluent primary cultures of serum-deprived rat aortic smooth muscle cells have revealed spontaneous oscillations in intracellular calcium concentration ([Ca](i)). The transients consist of a rapid increase in [Ca](i) that averages 60 nM and lasts ~30 s. They are caused by intracellular calcium release and an influx of extracellular calcium. Exposure of cells to the calcium-channel antagonists verapamil and diltiazem or incubation in nominally calcium-free medium reduced both the duration and amplitude of the transients; in contrast, the calcium-channel agonist (-)BAY K 8644 increased their duration. The transients were abolished by caffeine and 8-(N,N-diethylamino)octyl 3,4,5,-trimethoxybenzoate, agents that interfere with calcium release from the sarcoplasmic reticulum. These findings demonstrate that the sarcoplasmic reticulum is a primary source for the spontaneous oscillations in cytoplasmic calcium and is closely associated with the influx of extracellular calcium. Although the function of these transients is unclear, they may be involved in the spontaneous contractions observed in some vessels and in the regulation of vascular resistance

Na-H Antiport in Cultured Rat Aortic Smooth-Muscle - its Role in Cytoplasmic Ph Regulation

We have investigated the role of the Na-H antiport in the regulation of intracellular pH (pH(i)) in vascular smooth muscle. Experiments were conducted on contractile-state rat aortic smooth muscle cells grown in primary culture and loaded with the pH-sensitive, fluorescent indicator 2',7',-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF). Cells equilibrated in a normal physiological salt solution (PSS) containing 135 mM Na, pH 7.4 at 37°C, had a pH(i) of 7.16 ± 0.04 (means ± SE; n=8). 5-(N-ethyl-N-isopropyl)amiloride (EIPA) caused a concentration-dependent fall in pH(i). Removal of extracellular Na caused an intracellular acidification that was rapidly reversed on replacement of Na. The rate of recovery from NHCl-induced intracellular acidosis was dependent on extracellular Na concentration (K(m) 14.6 ± 2.8 mM) and was accelerated by increasing the transmembrane Na gradient and slowed by decreasing it. Recovery from acidosis was completely abolished by either EIPA or the absence of extracellular Na. These results demonstrate that the Na-H antiport is an important mechanism for the maintenance and regulation of pH(i) in vascular smooth muscle cells. The BCECF fluorescence technique provides an ideal method for further studies on the mechanisms for pH(i) regulation in these cells