Controlling type I errors for two-stage bioequivalence study designs

Recent publications have introduced sequential (two-stage) designs for investigation of bioequivalence in cross-over trials and the occurrence of type I errors have been investigated using trial simulations. They have so far focused on Test:Reference ratio of 0.95 and 0.9 and it has been observed that type I errors above 0.05 may occur. In this paper the behavior of two-stage designs for investigations of bioequivalence is being further investigated, and it is concluded that the existing methods do not universally control type I errors to an acceptable level, and they have the disadvantage of not using the observed Test:Reference from stage 1 in the dimensioning of stage 2. It is observed that type I errors and the alpha at the second stage follow an approximately linear relation in the region of type I errors of 0.05. This principle is used to propose a method that uses both the CV and Test:Reference ratio and which targets specifically a type I error level of 0.05. This is done by using simulation after stage 1 to identify an optimal value for the second alpha. An example is given which illustrates how the method may be associated with both an ethical and economical advantage.     

Molecular determinants on the insect sodium channel for the specific action of type II pyrethroid insecticides

Pyrethroid insecticides are classified as type I or type II based on their distinct symptomology and effects on sodium channel gating. Structurally, type II pyrethroids possess an α-cyano group at the phenylbenzyl alcohol position, which is lacking in type I pyrethroids. Both type I and type II pyrethroids inhibit deactivation consequently prolonging the opening of sodium channels. However, type II pyrethroids inhibit the deactivation of sodium channels to a greater extent than type I pyrethroids inducing much slower decaying of tail currents upon repolarization. The molecular basis of a type II-specific action, however, is not known. Here we report the identification of a residue G¹¹¹¹ and two positively charged lysines immediately downstream of G¹¹¹¹ in the intracellular linker connecting domains II and III of the cockroach sodium channel that are specifically involved in the action of type II pyrethroids, but not in the action of type I pyrethroids. Deletion of G¹¹¹¹, a consequence of alternative splicing, reduced the sodium channel sensitivity to type II pyrethroids, but had no effect on channel sensitivity to type I pyrethroids. Interestingly, charge neutralization or charge reversal of two positively charged lysines (Ks) downstream of G¹¹¹¹ had a similar effect. These results provide the molecular insight into the type II-specific interaction of pyrethroids with the sodium channel at the molecular level.     

Difluoromethylornithine prevents the down-regulation of type I interferon receptors: a possible mechanism for a synergistic antiproliferative effect

Type I interferon and difluoromethylornithine have been shown to exert an antiproliferative effect, both alone and in combination, in several tumor cell lines. Using B16 melanoma cells, we have shown that these two drugs inhibit growth over 72 hr in vitro. The estimated ED50 values for difluoromethylornithine and type I interferon were 31.1 +/- 1.1 microM and 22.3 +/- 2.7 IU/ml, respectively. When used in combination, a marked synergism was observed, as detected by isobologram analysis. Type I interferon, at concentrations that exhibited synergistic activity with difluoromethylornithine, did not affect ornithine decarboxylase activity or intracellular polyamine concentrations. These data suggest that the synergistic antiproliferative effect of murine type I interferon in combination with difluoromethylornithine is not mediated via polyamine depletion. When we examined the type I interferon receptor numbers on the B16 cells exposed to 5 IU/ml murine type I interferon for 72 hr, a 40% decrease was observed, compared with that seen in control cells. Difluoromethylornithine, at 10 microM, did not affect type I interferon receptor numbers. However, when added to the cells in the presence of murine type I interferon, difluoromethylornithine completely inhibited down-regulation, suggesting that down-regulation of the type I interferon receptor is a polyamine-dependent process. These observations may provide a basis for enhancing the therapeutic efficacy of interferon treatment through control of interferon receptor down-regulation.     

黑河地区I型超敏反应患者变应原检测分析

目的：分析黑河地区I型超敏反应患者的常见变应原种类，为I型超敏反应疾病的防治提供可靠依据。方法：对300例I型超敏反应患者进行变应原皮肤点刺试验。采用北京新华联协和药业有限责任公司生产的变应原点刺试剂，选择常见的39种变应原液。结果：300例I型超敏反应患者吸入变应原皮试阳性率以室内尘土、螨最高，分别为69．7％和68．3％；枕垫料、春季花粉、蒿属花粉皮试阳性率分别达到57．7％、38．4％、36．7％；食物变应原检测中海鱼、虾、芝麻、鸡蛋、羊肉的阳性率分别为35．7％、35．0％、34．3％、33．7％、32．3％。结论：变应原点刺试验易于操作，有助于寻找变应原，尽可能避免接触变应原，为进一步的脱敏治疗提供依据。     

我院Ⅰ类切口手术围术期预防用抗菌药物现状和管理对策

目的 探讨我院Ⅰ类切口手术围术期预防用抗菌药物的现状和管理对策.方法 对我院102例Ⅰ类切口清洁手术围术期预防用抗菌药物进行合理性分析,探讨管理对策.结果 通过调查发现我院Ⅰ类切口手术围术期预防用抗菌药物存在用药指征、用药种类、用药时机、用药时间不合理的现状.结论 加强围术期抗菌药物使用的管理和监督意义重大.     

Discovery of a Lead Compound for Specific Inhibition of Type I Collagen Production in Fibrosis

Fibrosis is a major medical problem caused by excessive synthesis of the extracellular matrix, composed predominantly of type I collagen, in various tissues. There are no approved antifibrotic drugs, and the major obstacle in finding clinically relevant compounds is the lack of specificity of current experimental drugs for type I collagen. Here we describe the discovery of a lead compound that specifically inhibited secretion of type I collagen by fibroblasts in culture at IC₅₀ = 4.5 μM. The inhibition was specific for type I collagen, because secretion of fibronectin was not affected. In vitro, the compound inhibited binding of LARP6, the master regulator of translation of type I collagen mRNAs, to the 5′ stem-loop sequence element which regulates their translation. Because binding of LARP6 to collagen mRNAs is crucial for the development of fibrosis, this inhibitor represents a promising lead for optimization into specific antifibrotic drugs.     

Assessment of type I error rates for the statistical sub-model in NONMEM

The aim of this study was to assess the type I error rate when applying the likelihood ratio (LR) test, for components of the statistical sub-model in NONMEM. Data were simulated from a pharmacokinetic one compartment intravenous bolus model. Two models were fitted to the data, the simulation model and a model containing one additional parameter, and the difference in objective function values between models was calculated. The additional parameter was either (i) a covariate effect on the interindividual variability in CL or V, (ii) a covariate effect on the residual error variability, (iii) a covariance term between CL and V, or (iv) interindividual variability in V. Factors in the simulation conditions (number of individuals and samples per individual, interindividual and residual error magnitude, residual error model) were varied systematically to assess their potential influence on the type I error rate. Different estimation methods within NONMEM were tried. When the first-order conditional estimation method with interaction (FOCE INTER) was used the estimated type I error rates for inclusion of a covariate effect (i) on the interindividual variability, or (ii) on the residual error variability, were in agreement with the type I error rate expected under the assumption that the model approximations made by the estimation method are negligible. When the residual error variability was increased, the type I error rates for (iii) inclusion of covariance between _CL–_V were inflated if the underlying residual distribution was lognormal, or if a normal distribution was combined with too little information in the data (too few samples per subject or sampling at uninformative time-points). For inclusion of (iv)_V, the type I error rates were affected by the underlying residual error distribution; with a normal distribution the estimated type I error rates were close to the expected, while if a non-normal distribution was used the type I errors rates increased with increasing residual variability. When the first-order (FO) estimation method was used the estimated type I error rates were higher than the expected in most situations. For the FOCE INTER method, but not the FO method, the LR test is appropriate when the underlying assumptions of normality of residuals, and of enough information in the data, hold true. Deviations from these assumptions may lead to inflated type I error rates.     

A decision rule for evaluating several independent clinical trials collectively

Usually, in applying for market approval of a new drug, more than one similarly designed clinical trial is conducted to support efficacy claims. How to evaluate these trials collectively and assess the overall type I error of a decision rule can be a challenging statistical issue. In this paper, we propose a decision rule to collectively evaluate p-values from several similarly designed and independently conducted trials. A concept of overall hypotheses, which is essentially union or intersection combinations of individual trials' hypotheses, is used so that the overall type I error can be controlled at desired levels. We also discuss some important properties of the approach, including the selection of the overall type I error rates and power. Examples are presented.     

I类切口手术围术期预防性应用抗菌药物合理性分析

目的：了解复旦大学附属肿瘤医院某科室I类切口手术围术期抗菌药物预防性使用的动态监测和干预效果,为临床合理用药提供参考。方法：抽取2010-2011年我院某科室各季度共240份I类切口手术病历,对围术期抗菌药物使用进行回顾性调查和评价。结果：某科室I类切口手术抗菌药物使用持续改善,用药率、用药品种和术后用药时间等指标明显改善。结论：经多部门联合干预,某科室I类切口手术抗菌药物预防性应用合理性大幅提高,干预效果显著。     

县医院I类切口手术预防用抗菌药物合理应用的影响因素*

目的：探讨与分析影响县医院I类切口手术预防用抗菌药物合理应用的因素,以促进抗菌药物的合理使用。方法：收集2018年6月到2019年6月在本院进行I类切口手术的患者2131例,调查患者的一般资料与预防用抗菌药物使用情况。结果：2018年第三季度、第四季度I 类切口手术抗菌药物预防使用率分别为40.5%、33.73%;2019年第一季度、第二季度I 类切口手术抗菌药物预防使用率分别为24.0%、25.0%。在2131例患者中,合理用药892例,合理率为41.9%;不合理用药1239例,不合格率为58.1%。单因素分析显示,基础疾病、手术时机、年龄、支付费用方式均为影响合理用药的重要因素（P<0.05）。多因素Logistic回归分析显示,基础疾病、手术时机、年龄、支付费用方式为影响县医院I类切口手术预防用抗菌药物合理应用的危险因素（P<0.05）。结论：县医院I类切口手术预防用抗菌药物的不合理用药比例较高,多为使用时机、使用疗程不当,基础疾病、手术时机、年龄、支付费用方式为主要的影响因素。     

A Decision Rule for Evaluating Several Independent Clinical Trials Collectively

Abstract

Usually, in applying for market approval of a new drug, more than one similarly designed clinical trial is conducted to support efficacy claims. How to evaluate these trials collectively and assess the overall type I error of a decision rule can be a challenging statistical issue. In this paper, we propose a decision rule to collectively evaluate p-values from several similarly designed and independently conducted trials. A concept of overall hypotheses, which is essentially union or intersection combinations of individual trials’ hypotheses, is used so that the overall type I error can be controlled at desired levels. We also discuss some important properties of the approach, including the selection of the overall type I error rates and power. Examples are presented.     

生长抑素治疗Ⅰ型肝肾综合征的疗效观察

目的 探讨生长抑素治疗Ⅰ型肝肾综合征的临床效果.方法 选择2010年6月～2012年8月本院收治的56例确诊为Ⅰ型肝肾综合征患者,将患者随机分为对照组和治疗组,每组各28例.对照组给予肝病基础、白蛋白及呋塞米治疗,治疗组在对照组的基础上给予生长抑素持续静脉泵入（250μg/h）.分别观察两组患者的血肌酐（SCr）、尿素氮（BUN）及尿量变化.结果 治疗前两组患者各项指标差异无统计学意义,治疗结束后,治疗组患者的肾功能SCr、BUN及尿量等指标均显著优于对照组（P＜0.01）.治疗组有效率为46.4％,显著高于对照组的21.4％ （P＜0.05）.结论 生长抑索对于Ⅰ型肝肾综合征疗效良好,患者病情明显好转,临床应用前景广阔.     

DSG—I型电脑肝病治疗仪治疗慢性乙型肝炎和肝炎肝硬化

目的观察DSG—Ⅰ型电脑肝病治疗仪治疗慢性乙型肝炎和肝炎肝硬化的疗效。方法129例慢性乙型病毒性肝炎和肝炎肝硬化患者随机分为两组，对照组给予常规药物治疗．治疗组在常规治疗的基础上加用DSGⅠ型（生物信息）电脑肝病治疗仪照射肝区。观察治疗前、后患者临床症状、肝功能、肝纤维化指标及外周血T细胞亚群、白细胞介素（IL）-2、IL-6、IL-8水平的变化。结果治疗后治疗组患者血清丙氨酸氨基转移酶、总胆红素、肝纤维化指标显著降低，自蛋白、MG和T4/T8比值显著升高，而治疗前增高的血清IL-2、IL-6、IL-8，随病情恢复而下降．同时失眠、肝区不适症状明显好转。结论DSGⅠ型电脑肝病治疗仪治疗能改善慢性乙型病毒性肝炎和肝炎肝硬化患者的临床症状．恢复肝功能，降低肝纤维化指标，且能激活人体的免疫系统，促进肝病康复。     

5 alpha-reductase in intact DU145 cells: evidence for isozyme I and evaluation of novel inhibitors

The epithelial-like human prostatic carcinoma cell line DU145, which expresses 5 alpha-reductase type I isozyme, was used to test a series of potential 5 alpha-reductase inhibitors. The exclusive expression of the type I isozyme was confirmed by PCR and subsequent DNA sequence analysis. Culture conditions were optimized for high conversion rates. Using this whole cell assay finasteride, 4MA, and 65 steroidal and non-steroidal compounds synthesized in our group were tested for their inhibitory activity. Inhibitors with IC50 values in the nanomolar range could be identified.     

Pharmacological properties of YM-11124, a selective immunosuppressive agent for cell-mediated immunity

Effect of YM-11124 on cell-mediated immune responses, type I to type III allergic reactions and inflammatory reaction was determined in mice, rats and guinea pigs. YM-11124 inhibited picryl chloride- and methylated bovine serum albumin-induced delayed-type hypersensitivity reactions by the treatment during both the sensitization and the elicitation phases in mice. Bilateral adrenalectomy did not prevent the suppression of DTH response by YM-11124. YM-11124 significantly prolonged the survival time of allogenic skin grafts in mice. Furthermore, YM-11124 inhibited the passive Arthus reaction in guinea pigs and the reversed passive Arthus reaction in rats. However, YM-11124 did not affect the passive cutaneous anaphylaxis reaction in rats, Forssman shock in guinea pigs and paw edema in rats. These results indicate that YM-11124 suppresses not only cell-mediated immune responses (type IV allergic reactions) but also type III allergic reactions without influence on types I and II allergic reactions as well as acute inflammation.     

Effect of surface characteristics of theophylline anhydrate powder on hygroscopic stability

The hygroscopicity of theophylline anhydrate has been investigated by gas adsorption and hydration kinetic methods. Type 1 theophylline anhydrate was obtained by recystallization from distilled water at 95 degrees C, and type II was obtained by dehydration of theophylline monohydrate. The X-ray diffraction pattern of types I and II agreed with the data of theophylline anhydrate. However, the diffraction peaks of the (200) and (400) planes of type I were much stronger than those of type II. The particles of type I were clear crystalline-like single crystals. However, the particles of type II had many cracks. The gas affinity balance (H/N) of type II, measured by gas adsorption, was about 7 times that of type I. After the hygroscopicity of types I and II had been tested at various levels of relative humidity (RH) at 35 degrees C, type I was stable at less than 82% RH, but transformed into the monohydrate at more than 88% RH. Type II was stable at less than 66% RH and transformed into the monohydrate at less than 75% RH. The hydration data of type I at 88% RH and type II at 75% RH were calculated for hydration kinetics using various solid-state kinetic models, but no particular model could be preferred from these data.     

The use of competitive inhibition of substrate-binding to cytochrome P450 in the determination of spectral dissociation constants for substrates with multiple types of binding,as illustrated with 1-butanol

A method is described, which allows (a) the detection of competitive inhibition of binding to cytochrome P450 between two substrates which elicit the same type of spectral change, and (b) the estimation of dissociation constants for one type of spectral binding of a substrate which exhibits multiple interaction with cytochrome P450. This method was used to investigate the interaction of 1-butanol with the type I binding site of cytochrome P450 in liver microsomes from female mice. 1-Butanol was found to competitively inhibit the binding of ethylmorphine, and has an apparent dissociation constant for type I binding of 30 mM.     

The relation between the sex-dependency of type I binding of ethylmorphine and the 1-butanol-induced spectral change in mouse liver microsomes

1. A sex difference in the spectral interaction of 1-butanol with liver microsomes from adult mice was observed. In males a profound reverse type I spectrum was elicited, whereas only a small spectral change of irregular shape was apparent in females. This sex difference is the opposite of that observed in the type I binding of ethylmorphine. In immature animals no sex difference was found. Testosterone pretreatment of female mice increased the size of the 1-butanol spectrum concomitantly with a decrease in ethylmorphine binding. 2. Microsomes from males and females did not contain different levels of endogenous substrates. Thus, the presence or displacement of such substrates does not explain the sex differences in type I and reverse type I binding respectively. 3. 1-Butanol was found to interfere with both type II and type I binding. It is concluded that the 1-butanol-induced spectral change consists of at least two components and that the sex difference is due to a sex-dependent type I component.     

A multispecific uptake system for taurocholate, cardiac glycosides and cationic drugs in the liver.

To test the hypothesis of multiplicity in carrier-mediated uptake mechanisms for organic cations in the liver and to study the possible relation with bile acid and cardiac glycoside uptake mechanisms, mutual interaction during uptake of various radiolabeled quaternary amines has been studied in isolated rat hepatocytes. Inhibition patterns at low concentrations (1 microM) of the presumed type I monovalent organic cation tri-n-butylmethylammonium were markedly different from those at relatively high concentrations (25 microM). Both the cardiac glycoside K-strophantoside and the bile acid taurocholate clearly reduced the uptake rate of tri-n-butylmethylammonium at 25 microM whereas these agents completely failed to reduce the uptake at low concentrations of the cation. Subsequently, inhibition of uptake of some multivalent amphipathic organic cations (muscle relaxants) for the type II uptake system was investigated. It was found that the uptake of these muscle relaxants both at tracer concentrations (< 1 microM) and at relatively high concentrations (25 microM) was decreased in the presence of low concentrations of the cardiac glycoside K-strophantoside, while taurocholate only inhibited the uptake at the concentration range > 25 microM of the muscle relaxants. Procainamide ethobromide, a typical type I organic cation, did not affect the uptake either at the low or high concentration range of the muscle relaxants. It is concluded that for each of the type I-like compounds and type II-like compounds tested at least two systems are involved in uptake into hepatocytes: tri-n-butylmethylammonium in a concentration range < or = 1 microM is mainly taken up by the type I uptake system and at concentrations > or = 25 microM also by system(s) that can be inhibited by taurocholate and K-strophantoside. Bulky amphipathic organic (type II) cations at concentrations < 1 microM are also transported by an uptake system that is inhibitable by cardiac glycosides but not by bile salts. At concentrations > 25 microM these compounds are predominantly accommodated by an uptake system that possibly mediates uptake of both cardiac glycosides and bile acids. This concept was supported by the observation that both type II organic cations and bile salts can inhibit ouabain uptake, while type II organic cations as well as the cardiac glycosides reduce taurocholate uptake rate. The present data support the idea that the liver seems to be equipped with a "multispecific" uptake system that transports hydrophobic compounds irrespective of charge, including some type I and type II organic cations at relatively high substrate concentrations.