A phenytoin-sensitive cationic current participates in generating the afterdepolarization and burst afterdischarge in rat neocortical pyramidal cells

We report here on the ionic mechanisms underlying the depolarizing afterpotential (DAP) in neocortical pyramidal cells, with special interest in those underlying the burst afterdischarge. Injections of short depolarizing current pulses under whole-cell current clamp with a CsCl-based internal medium generated, in most pyramidal cells, a single action potential with a plateau phase (plateau-AP), followed by a slowly decaying DAP both in the absence and presence of TTX. Under voltage-clamp, the same cells displayed a slow tail current (tail-I) at the offset of depolarization. When intracellular free Ca²⁺ was chelated with 10 mm BAPTA or when extracellular Ca²⁺ was replaced with equimolar Ba²⁺, neither the slow DAP nor the slow tail-I was observed. Extracellular application of Co²⁺ or Cd²⁺ reduced Ca²⁺ currents and the slow tail-I. Cation substitution experiments revealed that the channel generating the slow tail-I was permeable to K⁺ and Cs⁺ more than to Na⁺ (P_K≈P_Cs > P_Na > P_NMDG≈P_TEA). The cationic slow tail-I was not reduced by applying antagonists of the metabotropic glutamate receptor (MCPG, 1 mm ) and the muscarinic receptor (atropine, 1–10 μm ). Thus, the slow DAP was produced by activation of the cationic channel whose gating is solely dependent on [Ca²⁺]_i. An increase in [K⁺]_o from 3 to 6 or 9 mm enhanced the slow DAP, and resulted in a generation of burst afterdischarges. An anticonvulsant, phenytoin (PT; 1–10 μm ) suppressed the slow DAP while enhancing the plateau-AP in the presence of TTX, most likely by blocking the cationic channel.     

INVOLVEMENT OF PHOSPHOPROTEIN PHOSPHATASE 1 IN COLLAGEN-PLATELET INTERACTION

The binding of type I collagen to its receptor initiates platelet aggregation, but the relationship of the receptor to other signal transduction components is not yet established. Correlation of platelet aggregation and anti-type I collagen receptor antibody immunoprecipitation of type I collagen treated [³²PO4]-labeled platelets showed that there are two phosphoproteins (M_r 53 kDa and 21 kDa) that coprecipitated with the 65 kDa platelet type I collagen receptor. In the present investigation, we have identified one of the phosphoproteins. A soluble component the 100,000×g supernatant fraction of 53 kDa protein is recognized by polyclonal anti-PP1 antibody. The activity of the precipitated phosphatase is inhibited by okadaic acid and inhibitor 1, suggesting that it is protein phosphatase 1 (PP 1). Phosphorylation decreases PP 1 activity as was found with [³²PO4]-phosphorylase b as the substrate. The immunocoprecipitation of the type-1 collagen receptor and PP 1 inot the result of cross reactivity of the anti-type I collagen receptor antibody with the PP I protein. These results indicate that the platelet type I collagen receptor, PP 1, and unidentified 21 kDa protein are in close association with the platelet type I collagen receptor upon the binding of type I collagen by the receptor. Copyright © 1996 Elsevier Science Ltd     

Isolation of hepatic drug metabolism inhibitors from the seeds ofMyristica fragrans

The hexane extract from Nutmeg, the seed ofMyristica fragrans significantly inhibited hepatic drug-metabolizing enzyme activity. Through systematic fractionation by SiO₂ column and vacuum liquid chromatography monitoring by bioassay, three components, myristicin, (I), licarin-B(II) and dehydrodiisoeugenol(III) were isolated as active principles. Compounds II and III, with a single treatment (200 mg/kg, i.p.) showed not only a significant prolongation of hexobarbital-induced sleeping time but also a significant inhibition of aminopyrine N-demethylase and hexobarbital hydroxylase activities in mice. Compounds I and II provoked a sleep episode at a subhypnotic dose of HB, suggesting that they posses CNS-depressant properties.     

Synthesis of two nitro analogs of tranylcypromine: Relations of aromatic substitution of nitro groups to MAO-Inhibitory activity

Two new nitro analogs of tranylcypromine, (E)-2-(p-nitrophenyl)cyclopropylamine ((E)-p-NTCP) and (E)-2-(m-nitrophenyl)cyclopropylamine ((E)-m-NTCP) were synthesized in order to examine the effect of aromatic nitro substitution on the MAO-inhibitory activity of 2-phenylcyclopropylamines. The compounds were obtained by treatingt-butyl (E)-2-(p-nitrophenyl) cyclopropanecarbamate andt-butyl (E)-2-(m-nitrophenyl)cyclopropanecarbamate withp-toluenesulfonic acid in CH₃CN. Inhibitions of rat brain mitochondrial MAO-A and B by the compounds were examined using serotonin and benzylamine as the substrate at bothin vitro andex vivo levels. It was found fromin vitro measurements that(E)-p-NTCP at 6.0×10^?5M elicited merely 22.5% inhibition against MAO-B without any effect on MAO-A. In contrast,(E)-m-NTCP showed fair degrees of inhibitions of MAO-A and B with IC₅₀ values, 2.5×10^?7M and 1.4×10^?6M, respectively. It was also noted from(E)-m-NTCP thatm-nitro substitution caused a shift of selectivity of the inhibition toward MAO-A. According toex vivo measurements at 1.5, 3, 6, and 12 hr following the administration of a dose of 0.015 mmol/kg, i.p. to the rats, the inhibition percents of MAO-A by(E)-m-NTCP were 58.6, 63.7 63.6, and 46.6%, slightly lower than those observed by tranylcypromine. Whereas,(E)-p-NTCP at the same dose level did not show significant inhibitions against both MAO-A and MAO-B. Possible reasons for the difference in potencies between(E)-m-NTCP and(E)-p-NTCP were sought in relation to differing electron withdrawing effects ofm-andp-substituents which will influence electron density of the side chain amino functions and the partitions.     

Quantitation of protein adducts as a marker of genotoxic exposure: immunologic detection of benzo(a)pyrene -- globin adducts in mice

Immunologic methods have been developed for the determinationof benzo(a)pyrene (BP)-protein adducts and validated in animalstreated with (³H)BP. A previously developed antibody, 8E11,which recongnizes 7ß, 8-dihydroxy-9, 10-epoxy-7, 8,9, 10tetrahydrobenzo(a)pyrene (BPDE-I)-modified DNA or proteinas well as BPDE-I- tetraols, was used. The sensitivity of theassay was increased by enzymatic digestion of the modified proteinwith insoluble protease into peptides and amino acids beforeanalysis. In a competitive enzymelinked immunosorbent assay(ELISA) with digested BPDE-I-modified bovine serum albumin,50% inhibition occured at 400 fmol of adduct compared to 1450fmol for the nondigested albumin. Analysis of globin (Gb) isolatedfrom animals treated in vivo with 0.3–3 mg (³H)BP indicatedthat the ELISA could detect 90–100% of the adducts determinedby radioactivity. Levels of adducts in lung and liver DNA andserum albumin were correlated with the levels of Gb adducts.Of the total radioactivity associated with hemoglobin, only10% was from Gb while {small tilde}80% was from the heme fractionand the remainder from free BP metabolites. Significant cross-reactivityof antibody 8E11 was found with several BP-diols and phenols,suggesting that the immunoassay will not only be specific forBPDE-I adducts but will also detect adducts of other BP metabolitesas well as other aromatic hydrocarbon diol epoxides. An immunoaffinitycolumn of antibody 8E11 coupled to Sepharose 4B was used toisolate modified peptides from the digested Gb. About 65% ofthe applied radioactivity was retained on the column. Between1 and 2 mg of non-modified digested Gb could be added to thesample without interfering with binding of adducts. Proteindigestion and immunoaffinity chromatography should be usefulfor the measurement of protein adducts in biomonitoring studies.     

443例胃癌根治术后发生肺部并发症的危险因素

目的 探讨胃癌根治术术后肺部并发症(PPCs)的相关危险因素,为PPCs的个体化防治提供相应的对策。 方法 回顾性分析2019年1月至2021年3月兰州大学第二医院普通外科443例胃癌患者的临床资料,统计患者的临床病理特征,采用二分类Logistic回归分析胃癌根治术PPCs的危险因素。 结果 443例胃癌根治术PPCs的发生率为18.1%(80/443),其中肺部感染的发生率为12.4%(55/443),胸腔积液的发生率为11.7%(52/443),发生PPCs较未发生PPCs住院时间延长。Logistic回归分析显示,年龄≥60岁(OR=0.424、95%CI: 0.241~0.746)、糖尿病史(OR=0.318、95%CI: 0.146~0.693)、每分钟最大通气量(MVV)(%)<85%(OR=0.509、95%CI: 0.297~0.874)、术中失血量≥200 mL(OR=0.496、95%CI: 0.276~0.797)和术后吻合口并发症(OR=4.038、95%CI: 1.250~13.049)是胃癌根治术发生PPCs的独立危险因素。 结论 对于年龄≥60岁、糖尿病史、MVV(%)<85%、术中失血量≥200 mL、术后吻合口并发症的胃癌患者,应注意预防PPCs的发生。     

Comparison of the biomechanical effect of posterior condylar offset and kinematics between posterior cruciate-retaining and posterior-stabilized total knee arthroplasty

Background

The effect of the changes in the femoral posterior condylar offset (PCO) on anterior–posterior (AP) translation and internal–external (IE) rotation in cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) remains unknown. The purpose of this study was to compare the kinematics in CR and PS TKA with respect to the difference in prosthetic design and PCO change through a computational simulation.

The Validity of the Neale and Kendler Model-Fitting Approach in Examining the Etiology of Comorbidity

Given that knowledge regarding the etiology of comorbidity between disorders can have a significant impact on research regarding the classification, treatment, and etiology of the disorders, the ability to reject incorrect hypotheses regarding the causes of comorbidity is very important. A simulation study was conducted to assess the validity of the Neale and Kendler (1995) model-fitting approach in examining the etiology of comorbidity between two disorders. First, data were simulated under the assumptions of the 13 alternative comorbidity models described by Neale and Kendler. Second, model-fitting analyses testing the comorbidity models were conducted on the simulated datasets. Thirteen sets of data with varying model parameters were simulated to test Neale and Kendler's assertion that their model-fitting approach is appropriate across a range of potential prevalences and degrees of familiality. The validity of the model-fitting approach in examining unselected twin data and a combination of selected family data and unselected family data was explored. The model-fitting approach successfully discriminated several classes of comorbidity models, although discrimination between models within classes of related models was less accurate. Results suggest that the model-fitting approach can be a useful tool in examining the etiology of the comorbidity between disorders if the caveats of the present study's results are considered carefully. As predicted by Neale and Kendler, variations in the disorder prevalences and familial correlations did not affect the validity of their model-fitting approach, but affected the power to discriminate the correct model. As suggested by Neale and Kendler, the model-fitting approach can be applied to both unselected and selected data and to both twin and family data.     

An azurocidin-like protein is induced in Trichoplusia ni larval gut cells after bacterial challenge

Trichoplusia ni immune genes up-regulated in response to bacterial infection have been isolated using differential display polymerase chain reaction. Here we report the cloning and characterisation of a gut-specific immune gene encoding an azurocidin-like protein. The deduced protein is 317 amino acid residues long with a hydrophobic C-terminus and a predicted 17-residue signal peptide. The mature T. ni protein shows 30% identity to human azurocidin, an antibacterial protein. Like azurocidin, the T. ni protein contains two amino acid substitutions in the active site triad normally present in serine proteases. The T. ni protein was synthesised with a six-histidine C-terminal extension using the baculovirus expression system. Sequencing of the recombinant azurocidin-like protein confirmed the predicted cleavage of the signal peptide. Northern blots show that T. ni azurocidin-like protein is expressed solely in the larval gut and that expression is up-regulated by injecting or feeding bacteria. Expression reaches its highest level at 10 h after bacteria injection.