Clustering of autoimmune disease in parents of siblings from the Type 1 diabetes Warren repository.

AIMS: Autoimmune disorders co-exist in the same individuals and in families, implying a shared aetiology. The aim of this study was to compare the prevalence of the common autoimmune diseases in the parents of siblings from the Type 1 diabetes Warren repository with the general population. METHODS: Between 1989 and 1996, 505 British families with at least two siblings affected by Type 1 diabetes were recruited. Clinical information was collected regarding the presence of autoimmune disease in the parents and the prevalence of disease in the parents was compared with that expected in the general population. RESULTS: The prevalence of autoimmune disease in the parents was significantly higher in the repository compared with that expected in the general population [P-value = 1.98 x 10(-5) (female), P-value = 1.1 x 10(-8) (male)]. Type 1 diabetes was recorded in 63/1010 (6.2%) parents with a marked paternal preponderance (9.5 vs. 3%P = 0.002). Other autoimmune diseases affected 27% of parents with diabetes and 13.2% of parents without diabetes (P < 0.01). CONCLUSION: These data confirm the importance of family history as a significant risk factor for the development of Type 1 diabetes and support the hypothesis that the common autoimmune diseases share at least some aetiological mechanisms.     

基于实验均方误差F值的基因表达数据最佳聚类评判方法研究

目的 近年来产生了一些用于分析基因表达数据的聚类算法，却很少有关于评价聚类算法方法的研究。本研究的目的是尝试建立一个定量的评价基因表达数据聚类结果的方法。方法 本研究提供了一个系统的评价聚类结果的方法，利用我们提出的实验均方误差F值对几个常见的聚类算法进行比较。结果 利用F值对类质量的评价和利用已有的生物学知识对类进行分析的结果一致。结论 实验均方误差F值可以定量地评判用于基因表达数据的聚类算法。     

Interocular mismatch in spatial frequency and directionality characteristics of striate cortical neurones

Summary Spatial-frequency dependence of directional tuning and directional bias was compared, for both eyes, in four previously established discrete classes of binocular feline striate cortical neurones. Two classes (respectively direction-selective or bidirectional at optimal spatial frequency) were directionality invariant at all spatial frequencies. In the remaining two classes, both directionbiased at optimal spatial frequency, directional bias either altered or reversed with change in spatial frequency. In all four classes, the directional tuning of a majority of neurones sharpened at high spatial frequency through either eye, although the bandpass characteristics were sometimes dissimilar for the two eyes. All neurones were of the same type through either eye. Amongst the two classes of direction-biased neurones, the strength of bias was commonly different through the two eyes. Where reversal of bias occurred, that reversal took place at different spatial frequencies for each eye. Thus, the direction and orientation preferences of cortical neurones are fixed at optimal spatial frequency, but their envelope of tuning to a gamut of spatial frequencies is not. These differences are potentially related to binocular coding of visual perspective, including dynamic object rotation in visual space.     

Separation discrimination with embedded targets

Previous research has shown that separation discrimination thresholds are independent of the internal spatial scale (local spatial frequency) of the targets whose separation is being judged. The experiments reported here tested the generality of this conclusion for separation discrimination of targets that were embedded in an array of identical objects, where crowding could enhance the importance of the scale at which the individual target locations are encoded. No effect of the local spatial scale of the targets was found under these conditions.     

Unsupervised fuzzy clustering analysis supports behavioral cutoff criteria in an animal model of posttraumatic stress disorder.

BACKGROUND: Unsupervised fuzzy clustering (UFC) analysis is a mathematical technique that groups together objects in the multidimensional feature space according to a specified similarity measurement, thereby yielding clusters of similar data points that can be represented by a set of prototypes or centroids. METHODS: Since clinical studies of mental disorders distinguish between affected and unaffected individuals, we designed an inclusion/exclusion criteria (cutoff behavioral criteria [CBC]) approach for animal behavioral studies. The effect of classifying the study population into clearly affected versus clearly unaffected individuals according to behaviors on two behavioral paradigms was statistically significant. RESULTS: Here the raw data from previous studies were subjected to UFC algorithms as a means of objectively testing the validity of the concept of the CBC for our experimental model. The first UFC algorithm yielded two clearly discrete clusters, found to consist almost exclusively of the exposed animals in the one and unexposed animals in the other. The second algorithm yielded three clusters corresponding to animals designated as clearly affected, partially affected, and clearly unaffected. The algorithm for physiological data in addition to behavioral data failed to elicit discrete clusters. CONCLUSIONS: The UFC analysis yielded data that support the conceptual contention of the CBC and lends additional validity to our previous behavioral studies.     

动脉数字减影血管造影的临床应用

本文报告８０例动脉数字减影血管造影（ＩＡＤＳＡ）的初步经验，特别着重影像质量的评价。在本组病例，ＩＡＤＳＡ主要用于头颅、颈部、肺、腹部以及先天性心脏病的诊断。本组未发生重大并发症。ＩＡＤＳＡ的优点是：（１）影像质量好；（２）用于ＩＡＤＳＡ的剂量和浓度以及导管的直径均较用于常规血管造影的小得多，因此其副作用和并发症显著减少；（３）检查时间显著缩短，因此，ＩＡＤＳＡ对介入放射学治疗特别有用；（４）ＩＡＤＳＡ现已大部取代常规血管造影来诊断多种疾病。     

Determination of tissue optical properties by steady-state spatial frequency-domain reflectometry

A new non-invasive method to measure the optical properties of biological tissue is described. This method consists of illuminating the investigated sample with light which is spatially periodically modulated in intensity. The spatial modulation of the backscattered light and the diffuse reflectivity of the sample, both detected with an imaging technique, are used to deduce the absorption and reduced scattering coefficient from a table generated by Monte Carlo simulations. This principle has three major advantages: Firstly, it permits the immediate acquisition of the average values of the optical coefficients over a relatively large area (typ. 20 mm in diameter), thus avoiding the perturbations generated by small tissue heterogeneities; It also provides good flexibility for measuring the optical coefficients at various wavelengths and it does not require the use of a detector with a large dynamic range. The method was first validated on phantoms with known optical properties. Finally, we measured the optical properties of human skin at 400 nm, 500 nm, 633 nm and 700 nm in vivo.     

Sex and Intrauterine Position Influence the Size of the Gerbil Hippocampus

Sex differences in home range size and spatial ability are predictive of sex differences in the relative size of the hippocampus in rodents. Such differences in behavior and hippocampal volume are presumed to be, in part, the result of differences in perinatal exposure to hormones. We predicted from differences in the size of home ranges of male and female Mongolian gerbils (Meriones unguiculatus) in the wild that the hippocampus of male gerbils would be relatively larger than that of females. We examined the effect of prenatal hormonal influences on hippocampal size by comparing hippocampal volume of males and females from 2F and 2M intrauterine positions to that of randomly selected males and females. We found that, as predicted, randomly selected males had a significantly larger hippocampus, relative to telencephalon, than did randomly selected females. However, males and females from 2F and 2M intrauterine positions did not differ in relative hippocampal size. Possible explanations for the absence of a sex difference in hippocampal size in male and female gerbils from 2F and 2M intrauterine positions are discussed.