Effects of local administrations of tempol and diethyldithio-carbamic on peripheral nerve activity

We have recently shown that systemic administration of a superoxide dismutase mimetic, tempol, resulted in decreases in mean arterial pressure and heart rate along with a reduction in renal sympathetic nerve activity (RSNA). It has also been shown that these parameters are significantly increased by systemic administration of a superoxide dismutase inhibitor, diethyldithio-carbamic (DETC), indicating a potential role of reactive oxygen species in the regulation of RSNA. In this study, we examined the effects of local administrations of 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (tempol) and DETC on RSNA in anesthetized rats. Either tempol or DETC was directly administered onto the renal sympathetic nerves located between the electrode and ganglion. Local application of tempol (10 microL, 0.17 to 1.7 mol/L, n=6) resulted in dose-dependent decreases in integrated RSNA (by -81+/-6% at 1.7 mol/L) without alterations in mean arterial pressure and heart rate. In contrast, DETC (10 microL, 0.17 to 1.7 mol/L, n=6) increased RSNA dose-dependently. The responses of RSNA to tempol and DETC were significantly greater in spontaneously hypertensive rats than in normotensive rats (n=6, respectively). Local application of sodium nitroprusside (1 mmol/L) or N(G)-nitro-L-arginine methyl ester (0.11 mol/L) altered neither basal RSNA nor tempol-induced reductions in RSNA (n=6 and 5, respectively). A voltage-gated potassium channel blocker, 4-aminopyridine (0.1 mol/L), significantly decreased basal RSNA (by -81+/-1%) and completely prevented DETC-induced increases in RSNA (n=5). These results suggest that reactive oxygen species play a role in the regulation of peripheral sympathetic nerve activity, and that at least part of this mechanism is mediated through voltage-gated potassium channels.     

Diagnostic criteria for atypical hemolytic uremic syndrome proposed by the joint committee of the Japanese society of nephrology and the Japan pediatric society

Atypical hemolytic uremic syndrome (aHUS) is rare and comprises the triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Recently, abnormalities in the mechanisms underlying complement regulation have been focused upon as causes of aHUS. The prognosis for patients who present with aHUS is very poor, with the first aHUS attack being associated with a mortality rate of ~25 %, and with ~50 % of cases resulting in end-stage renal disease requiring dialysis. If treatment is delayed, there is a high risk of this syndrome progressing to renal failure. Therefore, we have developed diagnostic criteria for aHUS to enable its early diagnosis and to facilitate the timely initiation of appropriate treatment. We hope these diagnostic criteria will be disseminated to as many clinicians as possible and that they will be used widely.     

Ammonia decomposition over Ni catalysts supported on perovskite-type oxides for the on-site generation of hydrogen

Ammonia decomposition has attracted increasing attention as a promising process for the on-site generation of hydrogen. In this study, Ni catalysts supported on perovskite-type oxides (ABO₃) were prepared and the activity for ammonia decomposition was examined. The Ni/ANbO₃ (A = Na and K) and Ni/AEMnO₃ (AE = Ca, Sr, and Ba) catalysts were less effective for this reaction. Meanwhile, the Ni/REAlO₃ (RE = La, Sm, and Gd) catalysts exhibited relatively high activity. For Ni/AETiO₃ and Ni/AEZrO₃, the performance strongly depended on the A-site element of the perovskite-type oxides, and the Sr and Ba elements were more effective than the Ca one in the respective series. The catalytic activity for Ni/AEZrO₃ was higher than Ni/AETiO₃ in the case of the same alkaline earth element, and Ni/BaZrO₃ was the most active among the samples investigated in this work. For these series, the order in the performance corresponded well with that in the basic property. The nitrogen desorption profiles revealed that the evolution of nitrogen atoms, which is one of the kinetically slow steps, effectively proceeded for Ni/SrZrO₃ and Ni/BaZrO₃ compared with the conventional Ni catalysts. This promotion effect would be ascribed to the strong basic properties of the SrZrO₃ and BaZrO₃ supports, resulting in the high activity of Ni/SrZrO₃ and Ni/BaZrO₃ for ammonia decomposition.

Ni/SrZrO₃ and Ni/BaZrO₃ catalysts showed high activity for ammonia decomposition since these supports promoted the nitrogen desorption step.     

Elevated levels of soluble fibrin in patients with venous thromboembolism

The fibrin-related markers (FRMs), including soluble fibrin (SF), d-dimer and fibrin and fibrinogen degradation products (FDP) are considered to be useful for the diagnosis of thrombosis; however, evidence for the diagnosis of thrombosis by SF is still not well established. The present study was designed to evaluate the usefulness of SF in the diagnosis of venous thromboembolism (VTE). The plasma concentrations of FRMs were measured in 551 in-patients suspected to have a VTE. The plasma levels of SF, d-dimer and FDP were significantly higher in patients with VTE than patients without VTE and those were significantly higher in patients without VTE than in healthy volunteers. In a receiver operating characteristic analysis for the diagnosis of VTE, the area under the curve was 0.950 for SF, 0.933 for FDP and 0.805 for d-dimer. The appropriate cut-off values for the diagnosis were as follows SF 5.9 μg/ml, FDP 2.1 μg/ml and d-dimer 4.8 μg/ml. To obtain a 100% negative predictive value for the diagnosis of VTE, the SF was less than 5.2 μg/ml, FDP was less than 1.3 μg/ml, and d-dimer was less than 0.5 μg/ml. Our findings suggest that the SF assay is useful for the diagnosis and exclusion of VTE.