The effects of 2-thiophenecarboxylic acid on serum ionic calcium and magnesium levels in rats

1. Administration of 2-thiophenecarboxylic acid to rats maintained on a low calcium diet resulted in a significant depression in the serum levels of total and ionized calcium and inorganic phosphate. 2. The serum magnesium levels were not altered by the drug.     

Limited efficacy of calcium and magnesium in a porcine model of hydrofluoric acid ingestion

Objective

This investigation evaluated the effectiveness of calcium and magnesium in treating oral hydrofluoric acid (HF) poisoning.

Methods

The controlled laboratory investigation used anesthetized pigs. Subjects received HF via NG tube, titrated to abolish electrocardiographic abnormalities. The untreated group received saline infusion. The treatment group received serial injections of calcium chloride (CaCl₂) and magnesium chloride (MgCl₂). A third group received oral infusions of Calcium fluoride (CaF₂). We measured heart rate, QRS interval, pH, bicarbonate, calcium, magnesium, and potassium. The Wilcoxon Rank Sum test was used to compare intra- and inter-subject differences.

Results

Fatality occurred in all pigs receiving HF. Compared to the untreated group, trends for the treatment group were toward a larger amount of HF to produce fatality (83.1 ± 17.5 grams vs. 37.7 ± 16.1 grams, p = 0.08), to cause QRS prolongation (72.5 ± 25.8 vs. 33.8 ± 14.9 grams, p = 0.08), and to lower potassium at mortality (4.9 ± 0.7 vs. 8.7 ± 2.7 mEq/L, p = 0.08). No major changes in calcium (−1.0 ± 0.7 mEq/L) or magnesium (0.4 ± 0.6 mEq/L) occurred in the untreated group. Tachycardia developed in all pigs and ventricular arrhythmias occurred in 2 of 3 pigs of both groups [CaF₂ administration caused no QRS prolongation or ventricular arrhythmias and had no effect on laboratory parameters].

Conclusion

CaCl₂ and MgCl₂ replacement delayed but did not prevent fatality and QRS prolongation. Although this result suggests Ca++ and Mg++ may be beneficial in the treatment of systemic HF toxicity, factors other than hypocalcemia and hypomagnesemia play a role in toxicity.     

用正交实验优选人工肾透析液中钙、镁含量测定方法

目的:用正交设计优选人工肾透析液钙镁含量测定条件.方法:用L9(34)正交设计表对温度、掩蔽干扰离子的掩蔽剂进行多因素、多水平试验.结果:滴定的温度20℃、在被测溶液中加入适量的水、乙醇和三乙醇胺能使滴定终点突跃明显,终点易于判断.结论:采用优选条件后,能显著提高钙镁测定的精确度、准确度,重现性好.     

FPIA和HPLC法测定肾移植病人环孢素浓度比值的临床意义

环孢素(Cyclosporine A,CSA)是器官移植中有效的免疫抑制剂,然而CsA的肝、肾毒性限制了它的安全应用,而且诊断上与排斥反应不易区别。本文用FPIA和和HPLC法同时测定6例肾移植病人口服CsA后的50份血样中CsA浓度,两法相关系数r=0.85,斜率0.38。研究两法测定CsA浓度比值与肾功能的关系,以及比值对诊断肾毒性和排异反应的临床意义。     

液相色谱-串联质谱法测定人血浆中瑞舒伐他汀钙浓度及临床药代动力学研究

目的：建立测定人血浆中瑞舒伐他汀钙的液相色谱．串联质谱法，考察瑞舒伐他汀钙在中国健康志愿者体内的药代动力学。方法：含有瑞舒伐他汀钙和氟伐他汀钠的血浆样品经液-液提取后，进行色谱分析，在三重四极杆串联质谱仪上，以多反应离子监测方式进行定量分析。结果：瑞舒伐他汀钙的定量下限为0．03ng／mL，线形范围为0．03～60ng／mL，精密度与准确度符合生物样品分析要求。结论：该方法操作简便、快速、灵敏度高，适合瑞舒伐他汀钙的临床药代动力学研究。     

Neutrophil to CD4+ lymphocyte ratio as a potential biomarker in predicting virus negative conversion time in COVID-19

BackgroundSince December 2019, novel coronavirus (SARS-CoV-2)-infected pneumonia (COVID-19) occurred in Wuhan, and rapidly spread throughout China. Our study aimed to evaluate the robustness of neutrophil to CD4+ lymphocyte ratio (NCD4LR) in predicting the negative conversion time (NCT) of SARS-CoV-2 in COVID-19 patients.MethodsUnivariate and multivariate analysis were conducted to evaluate the independency of NCD4LR in predicting NCT. Receiver operating characteristic (ROC) curve analysis and area under the curve (AUC) were used to assess the diagnostic accuracy.ResultsCompared with low NCD4LR patients, patients with high NCD4LR had an older age; higher incidence of fever, fatigue, chest distress/breath shortness, severer disease assessment on admission; higher levels of inflammatory indicators; low levels of lymphocyte subsets, and a longer NCT. Multivariate analysis also identified NCD4LR as an independent risk factor for delayed NCT. ROC analysis showed that NCD4LR had a better performance than neutrophil to lymphocyte ratio in predicting the virus negative conversion within 2 weeks (AUC = 0.772), 3 weeks (AUC = 0.710), 4 weeks (AUC = 0.728), or 5 weeks (AUC = 0.815).ConclusionThis study suggests that NCD4LR is a potential and useful biomarker for predicting the virus negative conversion time in COVID-19 patients. Furthermore, due to the NCDLR value is easily calculated, it can be widely used as a clinical biomarker for disease progression and clinical outcomes in COVID-19 patients.     

Determination of myocardium to plasma concentration ratios of five antipsychotic drugs: comparison with their ability to induce arrhythmia and sudden death in clinical practice

Reviewing available data shows that most of antipsychotic drugs are associated with arrhythmia and sudden death. Experimental studies have shown a HERG channel blockade, a dose-dependent increase in duration of action potential or of QT interval, with various degrees of indicators of serious arrhythmogenicity. However, it seems difficult to relate these in vitro and in vivo preclinical models to clinical findings, in part, because the relationship between concentrations used and in vivo tissue concentrations during treatment in man is not known. Consequently, we established the myocardium to plasma concentration ratios for a series of antipsychotic drugs by intraperitoneal administration of different level doses to the guinea pig. Then, we compared these values to their ability to induce arrhythmia or torsade de pointes in clinical practice. The myocardium to plasma concentration ratios were 2.2 for clozapine, 2.7 for olanzapine, 3.1 for sertindole, 4.5 for risperidone, and 6.4 for haloperidol. These data suggest that when the ratio is higher than 4, arrhythmia and sudden death may be expected. On the contrary, when the ratio is less than 3, little effect may be predicted. These results underscore the importance of interpreting HERG channel data and electrophysiological data in the context of other pharmacokinetic parameters such as myocardium to plasma distribution.     

RP-HPLC法测定人体液中他唑巴坦浓度及其药动学应用

目的 :建立测定体液中他唑巴坦浓度的 HPLC方法 ,并应用于哌拉西林 /他唑巴坦健康人体的药代动力学研究。方法 :10名男性健康志愿者单剂量静脉滴注 4.5 g哌拉西林 /他唑巴坦钠 ,采用反相高效液相色谱 ( RP-HPLC)法测定血浆样品和尿中他唑巴坦药物浓度。 结果 :滴注完成即刻浓度 ( cm ax)为 ( 3 4.3 3± 8.0 5 )μg/m l,清除半衰期 ( t1 /2β)为 ( 0 .94± 0 .16) h,分布容积 ( Vd)为 ( 15 .43± 3 .82 ) L/kg,清除率 ( Clr)为 ( 15 .2 0± 2 .5 4) L /h,血药浓度 -时间曲线下面积 ( AUC)为 ( 4 2 .41±7.45 ) h·μg· ml-1 。结论 :他唑巴坦的体内过程符合二室开放模型 ,他唑巴坦主要以原形经肾脏排出体外 ,8h累积尿排百分率为 ( 78.68± 5 .84) %。     

alpha 1/alpha 2 Selectivity ratio in a series of agonists and their relation to pre/postsynaptic activity ratios

beta-Blocked pithed rats were used to obtained dose-response curves (blood-pressure increase) for 13 various alpha-adrenoceptor agonists of clinical and theoretical interest, in the absence and in the presence of the selective antagonists rauwolscine (alpha 2) and prazosin (alpha 1). Antagonist doses which shifted the dose-response curves for an agonist 10-fold to the right along the abscissa were then calculated (D10rauwolscine = D10R; D10prazosin = D10P). The ratio D10R/D10P is considered to be a quantitative estimation of an agonist's alpha 1/alpha 2 selectivity ratio. A correlation with post/presynaptic activity ratios is presented.     

Determination of SNX-2112, a selective Hsp90 inhibitor,in plasma samples by high-performance liquid chromatography and its application to pharmacokinetics in rats

A sensitive and specific reversed-phase high-performance liquid chromatography method with ultraviolet detection has been developed and validated for the identification and quantification of SNX-2112 in rat plasma. Following sample preparation using liquid–liquid extraction, the analytes were separated by the mobile phase acetonitrile–water (40:60, v/v) with an Agilent RP-HPLC column (ZORBAX SB-C18, 5 μm, 4.6 mm × 250 mm) at a flow rate of 1 ml/min, column temperature of 30 °C and detection wavelength of 251 nm. The retention time of SNX-2112 was 11.2 min. A good linear relationship was obtained in the concentration range studied (0.07–21 μg/ml, R² > 0.9982), and the LLOD and LLOQ for SNX-2112 were 0.02 and 0.07 μg/ml, respectively. The mean absolute recovery of SNX-2112 in plasma ranged from 88.58 to 99.61% at the studied concentrations. The intra- and inter-batch relative standard deviations were 1.7–3.5 and 1.9–4.4%, respectively. This method was successfully applied to pharmacokinetic studies in rats after intravenous administration of SNX-2112.     

Iron mobilization, cytoprotection, and inhibition of cell proliferation in normal and transformed rat hepatocyte cultures by the hydroxypyridinone CP411, compared to CP20: a biological and physicochemical study

The present study analyzes the iron mobilization, the cytoprotective, and the antiproliferative effects of the lipophilic hydroxypyridinone CP411, in comparison with the hydrophilic chelator CP20 or deferiprone used in the treatment of iron overload. Primary rat hepatocyte cultures and the rat hepatoma cell line Fao were used. Chelator cell uptake was evaluated by mass spectrometry in the two models. This method was also used to investigate the stability of the chelators in an acellular system as well as their scavenging and chelating effects against the hydroxyl radical generated by the Fenton reaction. The iron mobilization and the cytoprotective effects of the chelators were evaluated in primary cultures by measuring respectively 55Fe and lactate dehydrogenase release in the culture medium. The antiproliferative effect of the chelators was studied using the Fao cell line and measuring DNA synthesis by thymidine incorporation and DNA content by flow cytometry. We observed that CP411 entered the hepatocytes and the Fao cells respectively 4 and 13 times more than CP20. CP411 was 2.5 times more effective than CP20 to mobilize iron from preloaded hepatocytes. Pretreatment of the hepatocytes with CP20 or CP411 decreased the toxic effect of iron and CP411 was 1.6 times more effective than CP20. A dose-dependent decrease of DNA synthesis, correlated to an accumulation of cells in S phase, was observed in the Fao cell line in the presence of CP411, while CP20 was without effect. CP411 effect was inhibited by addition of iron simultaneously with the chelator, the addition of Zn or Cu was without effect. The inhibitory effect of CP411 was reversible since, 24hr after removal of the chelator, DNA replication reached the control level. The results show that CP411 is more efficient to protect the hepatocyte from the toxic effect of iron load and to inhibit tumor cell proliferation. Its higher efficiency may result from its better cell uptake since equimolar solutions of the two chelators in an acellular system exhibit the same ability to inhibit the Fenton reaction.     

The generality of nicotine as a reinforcer enhancer in rats: effects on responding maintained by primary and conditioned reinforcers and resistance to extinction

Rationale  Nicotine may enhance the reinforcing value of other reinforcers. It is unclear whether nicotine enhances responding maintained by all reinforcers or whether there are limits to this role. Objective  The objective of the study is to test the generality of nicotine-induced increases in reinforced responding by using an observing response procedure, which generated measures of responding maintained by food reinforcers, conditioned reinforcers, and responding during extinction. We also examined whether nicotine increased resistance to extinction and whether nicotine’s effects could be characterized as rate-dependent. Materials and methods  Rats received presession subcutaneous injections of Vehicle (n = 5), 0.3 (n = 6), or 0.56 (n = 6) mg/kg nicotine for 70 sessions. Resistance to extinction was also assessed by removing food for five sessions. Results  Nicotine did not consistently affect food or extinction responding. Both doses of nicotine produced increases in responding maintained by conditioned reinforcers, but did not increase resistance to extinction. Predrug response rates accounted for a small but significant percentage of the variance in the drug effect. Conclusion  Although there was a tendency for nicotine to increase low predrug response rates (i.e., response rates just prior to nicotine administration), 0.3 and 0.56 mg/kg nicotine systematically increased responding maintained by conditioned reinforcers. The results are consistent with a reinforcer-enhancing role of nicotine. However, nicotine did not increase resistance to extinction, nor did it increase food-maintained responses. Nicotine may selectively increase responding maintained by moderately reinforcing stimuli, such as the conditioned reinforcers used in the present study.     

Quantification of flupirtine and its active metabolite D-13223 in human plasma by LC-MS/MS: application to a clinical trial of flupirtine maleate capsules in healthy male Chinese volunteers

In the present study, we developed a simple, sensitive, precise, and accurate liquid chromatography-tandem mass spectrometric (LC-MS/MS) method and validated such approach for simultaneous determination of flupirtine and its active metabolite D-13223 in human plasma. The flupirtine, D-13223, and stable isotope internal standard (IS) were extracted from plasma samples by liquid-liquid extraction and chromatographed on a C18 column with a mobile phase consisting of acetonitrile–water–ammonia (55:45:0.1, v/v/v) at a flow rate of 0.25 mL/min. Detection was performed on a triple quadrupole tandem mass spectrometer with an electrospray ionization source (ESI) by multiple reaction monitoring (MRM) in positive ion mode. The linear calibration curves were obtained within the concentration range of 10.00–2000.00 ng/mL for flupirtine and 2.00–400.00 ng/mL for D-13223. The intra- and inter-run RSD, calculated from quality control (QC) samples, was less than 9.26% for flupirtine and D-13223. The accuracy was –5.80%–3.31% for flupirtine and D-13223. The extraction recoveries of flupirtine, D-13223, and their IS were all between 88.3%–97.2%. The method was successfully applied to investigate the pharmacokinetic profiles of flupirtine and its active metabolite D-13223 in human plasma following peroral administration of 100 mg flupirtine maleate capsules in healthy male Chinese volunteers.     

Activation of deoxycytidine kinase in lymphocytes is calcium dependent and involves a conformational change detectable by native immunostaining

Deoxycytidine kinase (dCK), the principal deoxynucleoside salvage enzyme, plays a seminal role in the bioactivation of a wide array of cytotoxic nucleoside analogues. Recently, activation of dCK has been considered as a protective cellular response to a number of DNA-damaging agents in lymphocytes. Regarding the molecular mechanism of the enzyme activation, a post-translational modification by protein phosphorylation has been suggested. Here we provide evidence that both the activation process and the maintenance of the activated state require free cytosolic calcium. BAPTA-AM, a cell-permeable calcium chelator selectively inhibited the activation of dCK in a time- and concentration-dependent manner while extracellular calcium depletion had no effect. On the other hand, elevation of cytoplasmic calcium levels by thapsigargin did not potentiate the enzyme, referring to the permissive function of calcium in the activation process. Denaturing Western blots of extracts from lymphocytes incubated with 2-chlorodeoxyadenosine, aphidicolin and/or BAPTA-AM clearly demonstrated that dCK protein levels were unchanged during these treatments. However, a striking correlation was found between enzyme activity and the intensity of dCK-specific signals in native Western blots. Extracts from CdA-treated cells were much better recognized by the antibody raised against the C-terminal peptide of dCK than the BAPTA-AM-treated samples. These results indicate that the calcium-dependent activation of dCK is accompanied by a conformational change that renders the C-terminal epitope more accessible to the antibody.