Circular dichroism detection in high-performance liquid chromatography: Evaluation of the anisotropy factor

The application of a circular dichroism (c.d.) detection system in HPLC using a chiral stationary phase is presented. The simultaneous measurement of the absorbance and c.d. signal allows the evaluation of the anisotropy factor (g = Δ/) and thus the determination of the enantiomeric excess (e.e.) of the eluates. When this detection system is used in preparative chiral chromatography the collection of the enantiomeric fractions can be readily optimized.     

In vitro/in vivo correlation of prolonged release dosage forms containing diltiazem HCl

Six preparations were considered: three multiple unit dosage forms (micropellets in capsules) (D, E and G) and one matrix tablet (B) were experimental prolonged release formulations, two non-disintegrating tablets (A and C) were commercial products. The in vitro dissolution behaviour of the differing formulations was investigated using the USP XXII paddle apparatus. The in vivo study was effected on a panel of 12 healthy volunteers. The two commercial tablets (A and C) showed mean dissolution time (MDT) of 1.34 and 1.44 h and t_d of 91 and 92 min, respectively; for prolonged release formulations (B, E, D, and G) MDT ranged between 2.28 and 4.23 h and t_d between 149 and 291 min. The mean residence time (MRT) was 8.68 and 6.47 h for tablets A and C, respectively; it ranged between 9.62 and 10.24 h for the multiple unit formulations E, D, and G and was 11.27 h for matrix B. Formulation B also showed the higher apparent elimination half-life t_1/2 (7.12 h), while apparent t_1/2 for all the other formulations were very similar, ranging between 5.04 and 5.28 h. High variability between the various formulations was found for C_max and AUC values, and no relationships could be established with the type of formulation. An in vitro/in vivo correlation was found for all the formulations examined on the basis of analogous parameters (MDT and MRT); (r = 0.83, p <0.05). In a few cases the Wagner-Nelson deconvolution method was applied to individual plasma level versus time curves and the corresponding absorption curves were obtained. In these cases the in vitro/in vivo correlation was tested on the basis of the comparison of the in vivo absorption curves with the in vitro dissolution profiles. This was accomplished using the ‘Levy's plot’ (per cent released versus per cent absorbed) approach and provided further support for the correlation found.     

饮水有机浓集物致突变活性影响因素的研究

本文探讨饮水有机物浓集流速及加氯量对致突变活性的影响。试验表明，饮水有机物浓集流速控制在每分钟２倍树脂柱床体积时，可获得最佳致突变效果。当加氯量≥２０ｍｇ／Ｌ时，对ＴＡ９８±Ｓ９和ＴＡ１００—Ｓ９菌株有致突变活性，≤２ｍｇ／Ｌ时对ＴＡ９８±Ｓ９和ＴＡ１００±Ｓ９菌株无致突变活性。为最大限度减少致突变效应，在净水过程中保证流行病学安全前提下，减少加氯量和加氯次数是十分必要的。     

Score Statistic to Test for Genetic Correlation for Proband-Family Design

In genetic epidemiological studies informative families are often oversampled to increase the power of a study. For a proband‐family design, where relatives of probands are sampled, we derive the score statistic to test for clustering of binary and quantitative traits within families due to genetic factors. The derived score statistic is robust to ascertainment scheme. We considered correlation due to unspecified genetic effects and/or due to sharing alleles identical by descent (IBD) at observed marker locations in a candidate region. A simulation study was carried out to study the distribution of the statistic under the null hypothesis in small data‐sets. To illustrate the score statistic, data from 33 families with type 2 diabetes mellitus (DM2) were analyzed. In addition to the binary outcome DM2 we also analyzed the quantitative outcome, body mass index (BMI). For both traits familial aggregation was highly significant. For DM2, also including IBD sharing at marker D3S3681 as a cause of correlation gave an even more significant result, which suggests the presence of a trait gene linked to this marker. We conclude that for the proband‐family design the score statistic is a powerful and robust tool for detecting clustering of outcomes.     

Conventional MRA and contrast- enhanced MRA of extracranial vessel segments

Summary The introduction of fast gradient systems allows a reliable visualization of the extracranial carotid vessels by the magnetic resonance angiography (MRA) which meanwhile is implemented into clinical routine. By the mainly applied time-of-flight (TOF) technique, vessels can be imaged without contrast agent (CA). Due to the application of ultra-fast gradient-echo-sequences, the first-pass evaluation of an intravenous bolus-injection of Gadolinium in the carotids from the aortic arch up to the skull base can be performed in less than 30 s. In this study, advantages and disadvantages of both techniques are discussed. For a qualitatively optimal contrast enhanced MRA (CE-MRA) timing parameters like injection delay, flow rate and the adjustment of sequence parameters have to be considered in relation to the fast venous return from the sinus to the jugular veins. First, the optimal time point of the data acquisition have been determined at a model and with a computer simulation in reference to the presence of CA in the arteries. As a result, 90 % of the contrast contribution is defined by 16 % of the symmetrically acquired central k-space lines. A measuring protocol for clinical use was obtained by a gradual variation of spacial resolution, measuring time and CA-injection parameters and was proved in normal volunteers and patients. An exact determination of the bolus-arrival-time by means of a test-bolus injection was acquired. The best qualitative results were achieved by a double-dose injection at 2 ml/s injection rate. The temporal reserves of ultra-fast sequences should be invested in the improvement of the spatial resolution. To date, further investigations related to the problem of optimal CA-application may improve the potentials of CE-MRA procedures.      

Studies of the effects of dietary zinc on the immune organs and cellular immunity in the rat

ＳｔｕｄｉｅｓｏｆｔｈｅｅｆｆｅｃｔｓｏｆｄｉｅｔａｒｙｚｉｎｃｏｎｔｈｅｉｍｍｕｎｅｏｒｇａｎｓａｎｄｃｅｌｌｕｌａｒｉｍｍｕｎｉｔｙｉｎｔｈｅｒａｔＷｕＪｉａｈｕｉ（吴嘉惠）；ＷｕＳｈｕｉｂｉｎｇ（吴水冰）；ＢａｉＪｉａｓｉ（白家驷）；ＫｏｎｇＸ...     

基因定量检测方法研究进展

基因定量检测已经成为研究基因组变异以及由于基因重组所引起的相关疾病的重要手段。大片段的基因组的重复和缺失可以引起致病突变。使用PCR和测序等定性检测方法很难探测到杂合状态的缺失和重复,因此探寻高效、可靠、灵敏的基因定量检测方法是当务之急。在过去的几年中已经相继出现了一些自动高效的技术方法。现在可用的基因定量方法大致可以分成3类:DNA印迹技术,细胞遗传学方法和以PCR扩增为基础的定量。本文对基因定量的最新进展作一综述,探讨其优缺点以期对定量研究方法的选择有所帮助。     

131Ⅰ治疗Graves病剂量探讨

目的　探讨1 31 Ⅰ治疗Graves病时 ,不同的剂量计算方法与治愈率以及治疗后并发症的关系。方法　在计算治疗Graves病所需1 31 Ⅰ时 ,分别采取不同的两种计算方法 ,观察两者治愈率及并发症的发生情况 ,并做多因素对比分析。结果　治疗组较对照组 1次治愈率提高约 12 % ,近期甲状腺功能减退延续为永久性甲状腺功能减退者亦明显减少 ,治疗效果明显优于后者。结论　1 31 Ⅰ治疗剂量计算时 ,既要有公式的规范性 ,又要有根据具体情况调节的灵活性 ,即可明显提高治疗效果     

复方卡托普利片中氢氯噻嗪的含量及均匀度测定

用紫外分光度法直接溯定复方卡托普利片中氢氯噻嗪的含量及均匀度。测定波长为272±1nm,平均回收率100.2%,变异系数0.3%,吸收度与氢氯噻嗪的浓度在1～10μg/ml 范围内具有线性关系。     

Dosage compensation, the origin and the afterlife of sex chromosomes

Over the past 100 years Drosophila has been developed into an outstanding model system for the study of evolutionary processes. A fascinating aspect of evolution is the differentiation of sex chromosomes. Organisms with highly differentiated sex chromosomes, such as the mammalian X and Y, must compensate for the imbalance in gene dosage that this creates. The need to adjust the expression of sex-linked genes is a potent force driving the rise of regulatory mechanisms that act on an entire chromosome. This review will contrast the process of dosage compensation in Drosophila with the divergent strategies adopted by other model organisms. While the machinery of sex chromosome compensation is different in each instance, all share the ability to direct chromatin modifications to an entire chromosome. This review will also explore the idea that chromosome-targeting systems are sometimes adapted for other purposes. This appears the likely source of a chromosome-wide targeting system displayed by the Drosophila fourth chromosome.