Ammonia addedin vitro,but not moderate hyperammonemiain vivo,stimulates glutamate uptake and H+-ATPase activity in synaptic vesicles of the rat brain

The uptake of radiolabelled neurotransmitters: glutamate (GLU), GABA, and dopamine (DA) and the activity of the vacuolar type H⁺-pumping ATPase (H⁺-ATPase), were measured in crude synaptic vesicles treatedin vitro with a neurotoxic (3 mM) dose of NH₄ ⁺ (acetate or chloride), or isolated from rats with a moderate increase of brain ammonia (to 0.6 mM) induced by i.p. administration of ammonium acetate (HA rats) or a hepatotoxin-thioacetamide (HE rats).In vitro treatment with ammonium salts increased the sodium-independent, chloride-dependent uptake of GLU but did not stimulate the uptake of GABA or DA. Thein vitro treatment also stimulated the H⁺-ATPase activity. Since H⁺-ATPase generates the electrochemical gradient driving synaptic vesicular neurotransmitter transport, its stimulation by ammonia may have facilitated GLU uptake. However the GLU specificity of the effect must be related to other factors differentially affecting GLU uptake and the uptake of other neurotransmitters. Enhanced GLU accumulation in the synaptic vesicles may contribute to the increase of synaptic GLU exocytosis previously reported to accompany acute increases of brain ammonia to toxic levels. However, GLU uptake and H⁺-ATPase activity, but also the uptake of GABA and DA, were unchanged in synaptic vesicles prepared from rats with HA or HE. This indicates that changes in GLU and/or GABA release reported for moderate hyperammonemic conditions must be elicited by factors unrelated to the synaptic vesicular transport of the amino acids.     

Renal excretory responses to single and repeated administration of diuretics in healthy subjects: Clinical connotations

Administration of an initial oral dose of hydrochlorothiazide 25 mg to healthy subjects is followed by increased 24-hour urinary outputs of sodium, chloride, and potassium. On the fourth day of once-daily dosing with hydrochlorothiazide 25 mg, 24-hour natriuresis and chloriuresis are no longer augmented, but the elevation in 24-hour kaliuresis that follows the first dose remains unchanged. Twenty-four-hour urinary calcium output is consistently reduced during repeated once-daily administration of hydrochlorothiazide 25 mg.The first oral dose of the loop diuretic torasemide augments the average natriuresis and kaliuresis in the 6 hours immediately after dosing in healthy subjects, in a dose-dependent fashion, within the 2.5 to 10-mg range. These increased urinary outputs are followed by rebounds below postplacebo values between 6 and 24 hours after dosing. As a result of this biphasic response, torasemide 2.5 mg qualifies as a nondiuretic formulation (it does not elevate 24-hour natriuresis), whereas torasemide 5 and 10 mg qualify as diuretic formulations. After the seventh dose of torasemide 5 or 10 mg during a regimen of once-daily therapy, 24-hour urinary sodium and chloride outputs no longer differ from their postplacebo counterparts. Twenty-four-hour kaliuresis tends to increase in a dose-dependent fashion after the first dose of torasemide (torasemide 2.5 and 5 mg do not augment it significantly), but this tendency is no longer present after the seventh once-daily dose, when torasemide (2.5, 5, or 10 mg) does not elevate the mean 24-hour kaliuresis. Twenty-four-hour calciuresis tends to increase in a dose-dependent manner (torasemide 2.5 mg does not elevate it significantly) after the first dose of torasemide; this calciuretic effect does not change in intensity after 7 days of once-daily treatment.     

Butyrate as an effective treatment of congenital chloride diarrhea

BACKGROUND & AIMS: Many therapeutic attempts have demonstrated to be ineffective in reducing the severity of congenital chloride diarrhea and its long-term complications. The short-chain fatty acid butyrate stimulates intestinal water and ion absorption through a variety of mechanisms, including the activation of a parallel Cl-/butyrate and Na+/H+ exchanger. In this case report, we report the therapeutic efficacy of butyrate on an 11-year-old patient affected by congenital chloride diarrhea. METHODS: The efficacy of increasing doses of oral butyrate (from 50 to 100 mg/kg/day) was investigated through the daily evaluation of stool volume, bowel movements, fecal incontinence, serum, and stool electrolytes concentrations. The modifications in transepithelial intestinal ion transport elicited by butyrate were examined by rectal dialysis study. RESULTS: A butyrate dose of 100 mg/kg/day induced a normalization of stool pattern and of serum and fecal electrolytes concentration. The rectal dialysis study demonstrated a proabsorptive effect induced by butyrate on Na+, Cl-, and K+ intestinal transport. Butyrate therapy was well tolerated during the entire 12-month observation period, and the stool pattern and fecal and serum ion concentrations remained stable within the normal ranges. No clinical adverse events or episodes of dehydration requiring hospital care were observed. CONCLUSIONS: Butyrate could be effective in treating congenital chloride diarrhea. It is easily administered, useful in preventing severe dehydration episodes, and may be a promising therapeutic approach for a long-term treatment in this rare and severe condition.     

奥扎格雷钠氯化钠(葡萄糖)注射液评价性抽验结果及分析

目的:评价奥扎格雷钠氯化钠注射液和奥扎格雷钠葡萄糖注射液的质量情况。方法:按照国家评价性抽验计划总体要求,采用法定检验方法结合探索性研究对来自5个厂家的53批样品进行检验,统计分析检验结果,并对2种注射液的质量现状进行评价。结果:法定检验显示奥扎格雷钠氯化钠(葡萄糖)注射液样品合格率分别为97.9%、100.0%;探索性研究显示产品中普遍存在两个杂质(杂质Ⅰ和杂质Ⅱ);灭菌工艺对产品质量无影响;渗透压摩尔浓度测定结果均在等渗范围内;细菌内毒素及无菌均符合规定。气-质联用法测定邻苯二甲酸酯类17种增塑剂的含量,样品中均含有微量的DIBP、DBP、DPP,但均在国家限度内。建立聚类分析模型,各厂家样品均能通过验证,并可与其他品种进行区分。结论:2种注射液按各执行标准检验,总体合格率较好,但存在如细菌内毒素限度及无菌检查方法需要规范统一等问题。建议改进并统一现行质量标准,进一步加强对奥扎格雷钠氯化钠(葡萄糖)注射液的监管。     

0.9%氯化钠注射液预充式导管冲洗器用于婴幼儿头皮静脉留置针封管150例效果观察

目的观察0．9％氯化钠注射液预充式导管冲洗器在婴幼儿头皮静脉留置针封管中的应用效果。方法将2012年1月至6月儿科住院的30d至2岁使用头皮静脉留置针患儿300例随机分为试验组和对照组,各150例。试验组采用0．9％氯化钠注射液预充式导管冲洗器封管,对照组使用注射器抽取5mL稀释肝素钠正压封管,比较两组单次留置时间内堵管、静脉炎、外渗的发生情况。结果试验组单次留置时间内堵管、静脉炎、外渗发生率均明显低于对照组（P〈0．01）。结论采用0．9％氯化钠注射液预充式导管冲洗器封管效果较好,值得临床推广。     

Short-term effects of electronic and tobacco cigarettes on exhaled nitric oxide

The objective of this study was to compare the short-term respiratory effects due to the inhalation of electronic and conventional tobacco cigarette-generated mainstream aerosols through the measurement of the exhaled nitric oxide (eNO). To this purpose, twenty-five smokers were asked to smoke a conventional cigarette and to vape an electronic cigarette (with and without nicotine), and an electronic cigarette without liquid (control session).     

Nitidine chloride induces apoptosis and inhibits tumor cell proliferation via suppressing ERK signaling pathway in renal cancer

Nitidine chloride (NC), a natural bioactive alkaloid derived from Zanthoxylum nitidum (Roxb) DC, has been shown to have inhibitory effects on various tumors. However, whether NC could exert anti-cancer activity and the underlying mechanisms have not been elucidated in renal cancer cells. In this study, we demonstrated the growth inhibitory and pro-apoptotic effects of NC on renal cancer cells both in vitro and in vivo. With cell viability and flow cytometric apoptosis assays, we found that NC potently suppressed the growth of 786-O and A498 cells in a time- and dose- dependent manner. Consistently, the xenograft model performed in nude mice exhibited reduced tumor growth with NC treatment. Mechanically, we presented that NC significantly decreased phosphorylation of ERK and Akt, accompanied by up-regulation of P53, Bax, cleavage caspase-3 and cleavage PARP, downregulation of Bcl-2, caspase-3 and PARP. Furthermore, a specific MEK inhibitor, PD98059, could potentiate the pro-apoptotic effects of NC, which indicated that NC might trigger apoptosis in renal cancer cells partly via inhibition of ERK activity. Taken together, our results imply that NC could be developed as a potential anticancer agent to renal cancer and worthy of further studies.     

Loop diuretics are open-channel blockers of the cystic fibrosis transmembrane conductance regulator with distinct kinetics

BACKGROUND AND PURPOSE

Loop diuretics are widely used to inhibit the Na⁺, K⁺, 2Cl⁻ co-transporter, but they also inhibit the cystic fibrosis transmembrane conductance regulator (CFTR) Cl⁻ channel. Here, we investigated the mechanism of CFTR inhibition by loop diuretics and explored the effects of chemical structure on channel blockade.

EXPERIMENTAL APPROACH

Using the patch-clamp technique, we tested the effects of bumetanide, furosemide, piretanide and xipamide on recombinant wild-type human CFTR.

KEY RESULTS

When added to the intracellular solution, loop diuretics inhibited CFTR Cl⁻ currents with potency approaching that of glibenclamide, a widely used CFTR blocker with some structural similarity to loop diuretics. To begin to study the kinetics of channel blockade, we examined the time dependence of macroscopic current inhibition following a hyperpolarizing voltage step. Like glibenclamide, piretanide blockade of CFTR was time and voltage dependent. By contrast, furosemide blockade was voltage dependent, but time independent. Consistent with these data, furosemide blocked individual CFTR Cl⁻ channels with ‘very fast’ speed and drug-induced blocking events overlapped brief channel closures, whereas piretanide inhibited individual channels with ‘intermediate’ speed and drug-induced blocking events were distinct from channel closures.

CONCLUSIONS AND IMPLICATIONS

Structure–activity analysis of the loop diuretics suggests that the phenoxy group present in bumetanide and piretanide, but absent in furosemide and xipamide, might account for the different kinetics of channel block by locking loop diuretics within the intracellular vestibule of the CFTR pore. We conclude that loop diuretics are open-channel blockers of CFTR with distinct kinetics, affected by molecular dimensions and lipophilicity.