Tris (1,3‐dichloro‐2‐propyl) phosphate induces toxicity by stimulating CaMK2 in PC12 cells

Tris (1,3‐dichloro‐2‐propyl) phosphate (TDCIPP) is one of the widely used organophosphorus flame retardants (OPFRs), which are regarded as suitable substitutes for brominated flame retardants (BFRs). Previously, we have validated the toxicity of TDCIPP in PC12 cells owing to the induced alterations in GAP43, NF‐H, CaMK2a/2b, and tubulin α/β proteins; however, limited information is currently available on the toxicity and mechanism of TDCIPP. In the present study, cytotoxicity effects were evaluated by exposing PC12 cells to different concentrations of TDCIPP (0–50 μM) for 4 days. To explore the possible mechanisms through which cytotoxicity is induced, changes in intracellular [Ca²⁺]_i levels and the activation of calmodulin dependent protein kinase 2 (CaMK2), c‐Jun N‐terminal kinase (JNK), extracellular regulated protein kinases (ERK1/2), and p38 mitogen‐activated protein kinases (MAPK) pathways were evaluated. Furthermore, PC12 cells were pretreated with CaMK2 inhibitor KN93 to investigate the relationship between TDCIPP‐induced phosphorylation of CaMK2 and activation of JNK, ERK1/2, and p38 MAPK pathways. Our results indicate that TDCIPP‐induced toxicity might be associated with the overload of [Ca²⁺]_i levels, increased phosphorylation of CaMK2, and activation of the JNK, ERK1/2, and p38 MAPK pathways, the lattermost of which was further demonstrated to be partially elicited by the CaMK2 phosphorylation.     

绝经后骨质疏松症发病相关危险因素及预防措施研究

目的:探讨绝经后骨质疏松症(PMOP)发病相关危险因素及预防措施.方法:筛选临床确诊为PMOP病人共176例,对所有病人的腰椎和髋骨部位的骨密度进行测量,同时统计所有病人的年龄、体质量、身高、绝经年限、生育情况和运动情况等作为影响因素,使用向后迭代法对影响因素进行考察,以病人骨密度是否减少作为因变量建立定序logistic模型,将通过考察的因素代入模型中进行权重考察,研究各因素对绝经后骨质疏松症发病的相关性,并探讨相关预防措施.结果:最终筛选年龄、体质量、绝经年限、生育情况、饮食习惯、目前运动习惯、年轻时期运动习惯对因变量有显著的解释能力,其中年龄、绝经年限、生育情况与骨质减少情况呈正相关,为发病危险因素,而体质量、饮食情况、目前运动情况和年轻时期运动情况与骨质减少情况呈负相关,是此类疾病的保护因素.结论:改善PMOP病人的饮食结构,适量增加病人体质量和脂肪含量,有效规划病人的日常运动情况能够有效地减慢病人骨密度降低的速度,有效控制PMOP发病率.     

Theoretical studies on the selective mechanisms of GSK3β and CDK2 by molecular dynamics simulations and free energy calculations

Glycogen synthase kinase 3 (GSK3) is a serine/threonine protein kinase which is widely involved in cell signaling and controls a broad number of cellular functions. GSK3 contains α and β isoforms, and GSK3β has received more attention and becomes an attractive drug target for the treatment of several diseases. The binding pocket of cyclin‐dependent kinase 2 (CDK2) shares high sequence identity to that of GSK3β, and therefore, the design of highly selective inhibitors toward GSK3β remains a big challenge. In this study, a computational strategy, which combines molecular docking, molecular dynamics simulations, free energy calculations, and umbrella sampling simulations, was employed to explore the binding mechanisms of two selective inhibitors to GSK3β and CDK2. The simulation results highlighted the key residues critical for GSK3β selectivity. It was observed that although GSK3β and CDK2 share the conserved ATP‐binding pockets, some different residues have significant contributions to protein selectivity. This study provides valuable information for understanding the GSK3β‐selective binding mechanisms and the rational design of selective GSK3β inhibitors.     

Ordinal response generalized difference in differences with varying categories: The health effect of a disability program in Korea

We consider the use of difference in differences (DD) to evaluate the effect of an activity assistance program on the health of severely disabled Koreans. There are, however, 2 problems in the data: the number of response categories for self‐assessed health changed over the waves of the repeated cross‐section survey and the “parallel untreated response path” assumption for DD is suspect. We show how to overcome these problems by renormalizing parameters and applying “generalized difference in differences (GDD).” We find a significantly positive effect of the program with DD, but not with GDD. Our solutions should prove useful in applications in which one or other of these problems arise.     

Estimation of parametric failure time distributions based on interval‐censored data with irregular dependent follow‐up

Event history studies based on disease clinic data often face several complications. Specifically, patients may visit the clinic irregularly, and the intermittent observation times could depend on disease‐related variables; this can cause a failure time outcome to be dependently interval‐censored. We propose a weighted estimating function approach so that dependently interval‐censored failure times can be analysed consistently. A so‐called inverse‐intensity‐of‐visit weight is employed to adjust for the informative inspection times. Left truncation of failure times can also be easily handled. Additionally, in observational studies, treatment assignments are typically non‐randomized and may depend on disease‐related variables. An inverse‐probability‐of‐treatment weight is applied to estimating functions to further adjust for measured confounders. Simulation studies are conducted to examine the finite sample performances of the proposed estimators. Finally, the Toronto Psoriatic Arthritis Cohort Study is used for illustration. Copyright © 2017 John Wiley & Sons, Ltd.     

Plasma glucose lowering effect of spartein sulphate infusion in non-insulin dependent (Type 2) diabetic subjects

Summary Sparteine sulphate, given i.v. as a bolus of 15 mg/ml plus 90 mg in 0.9% NaCl 100 ml over 60 min, increases plasma insulin and decreases plasma glucose and adrenaline in non-insulin dependent (Type II) diabetic subjects. The hypoglycaemic effect was also evident in the presence of a high plasma glucose level produced by Biostator changing glucose infusion from 20.2±2.8 to 26.4±4.2 mg · kg^–1 · min^–1 (p<0.01), and it was potentiated by simultaneous infusion of arginine.No additional effect of sparteine on the peripheral sensitivity to insulin were detected by the euglycaemic, hyperinsulinaemic glucose clamp technique, as the glucose infusion rate (3.1±0.8 vs 2.6±1.2 mg · kg^–1 · min^–1) was not statistically significant different in the last 60 min of the experiment.It is concluded that sparteine sulphate enhances -cell secretion, causing a fall in the plasma glucose concentration.     

The effect of verapamil on halothane-epinephrine or digitalis-induced ventricular dysrhythmias in dogs

The effect of verapamil on ventricular dysrhythmias was evaluated using two canine models. In one model, ventricular dysrhythmias were induced by 1% halothane-epinephrine (1.5 30µg/kg/min.) in 20 dogs (Group I). In the other model, ventricular dysrhythmias were induced by digoxin (0.1 0.2mg/kg) in 27 dogs (Group II). Verapamil (0.2 0.5mg/kg) was given to treat these ventricular dysrhythmias. When verapamil was ineffective, lidocaine (1 2mg/kg) was given following the administration of verapamil. In 7 dogs of group II, lidocaine alone was given. Verapamil was effective in 16 animals of group I, and in 10 animals of group II. Lidocaine was ineffective in the remaining 4 of group I, whereas effective in the remaining 17, including those given lidocaine alone of group II. From these findings, it was inferred that Ca²⁺ dependent abnormal automaticity and/or re-entry may be more closely related to the genesis of halothane-epinephrine-induced ventricular dysrhythmias refractory to lidocaine, whereas triggered activity may be more closely related to that of digitalis-induced ventricular dysrhythmias. In conclusion, verapamil was more effective against halothane-epinephrine-induced ventricular dysrhythmias than against digitalis-induced ventricular dysrhythmias.(Yoshizawa Y, Shimizu R, Kasuda H et al.: The effect of verapamil on halothan-epinephrine or digitalis-induced ventricular dysrhythmia in dogs. J Anesth 2: 28–35, 1988)     

UrinarypH and urine flow independent renal clearance of methotrexate in dogs

The effects of urine flow and pH on methotrexate renal clearance were studied in seven conditioned male Beagle-Mongrel dogs. Steady-state plasma methotrexate and inulin concentrations were achieved by i.v. infusions preceded by i.v. bolus doses. Plasma and urine concentrations of methotrexate were quantitated by a sensitive high-performance liquid Chromatographic assay, while those of inulin were measured by a colorimetric method. Since plasma protein binding of methotrexate was pH and concentration independent, methotrexate/inulin renal clearance without correcting for plasma binding was used for most of the data analyses. The results showed that the renal clearance ratios at the plasma methotrexate levels (approximately 0.1, 1.0, 20.0, and 100 g/ml) studied remained relatively constant when urine pH (differences of up to about 2.5 units) and flow rate (differences of up to approximately 30 times) were changed. This indicated that renal reabsorption of methotrexate in these dogs was negligible. However, concentration-dependent renal clearance was observed. The mean renal clearances were 3.84, 3.94, 2.73, and 2.72 ml/min/kg at plasma concentrations of about 0.1, 1.0, 20.0, and 100.0 g/ml, respectively, when urine was alkalized by sodium bicarbonate. The corresponding clearances were 4.02, 4.28, 2.62, and 2.65 ml/min/kg when urine was acidified by ammonium chloride. These showed the existence of saturable tubular secretion of methotrexate. No 7-hydroxy-methotrexate, a metabolite found in other species, was detected in the urine and plasma of the dogs.This research was supported in part by a grant from the National Cancer Institute, CA-29754. Abstracted from a dissertation submitted in 1984 by Chung Y. Lui to the Graduate College, University of Illinois at Chicago in partial fulfillment of Doctor of Philosophy Degree requirements.     

A bivariate logistic regression model based on latent variables

Bivariate observations of binary and ordinal data arise frequently and require a bivariate modeling approach in cases where one is interested in aspects of the marginal distributions as separate outcomes along with the association between the two. We consider methods for constructing such bivariate models based on latent variables with logistic marginals and propose a model based on the Ali-Mikhail-Haq bivariate logistic distribution. We motivate the model as an extension of that based on the Gumbel type 2 distribution as considered by other authors and as a bivariate extension of the logistic distribution, which preserves certain natural characteristics. Basic properties of the obtained model are studied and the proposed methods are illustrated through analysis of two data sets: a basic science cognitive experiment of visual recognition and awareness and a clinical data set describing assessments of walking disability among multiple sclerosis patients.