Weitere Untersuchungen zur Induktion von Keimblattveränderungen durch Röntgenstrahlen

Summary A previous experiment withEranthis showed thatRoentgen irradiation of undivided embryos led to a change in the number of cotyledons. In the present publication, the induction of anomalies of the cotyledon was shown after irradiation of early embryo stages on the mother plant in Arabidopsis thaliana, an example of a plant with complete embryos.Which aberration type (synkotyl, anisokotyl, trikotyl, tetrakotyl or multiple seedlings) will arise, seems to be determined neither by theRoentgen dose nor by the stage of development on irradiation. The appearance of predominately regular trikotyl types after application of 2000r, and their gradual disappearance with increasing doses in favour of the irregular trikotyl types, suggests that in the lower doses the main influences are upon the purely chemical reactions in the embryos, which are overlaid by cell damages occurring in a directly biophysical way with increase of the physical primary acts and lead to irregular growth.

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Die Arbeit wurde mit Unterstützung der Deutschen Forschungsgemeinschaft durchgeführt.     

具有Markov延迟的网络化控制系统控制与通信协同设计

由于网络化控制系统分析与设计的复杂性,其控制与通信协同设计问题一直没有得到解决。该文讨论了一类离散线性时不变网络化控制系统在服从介质访问约束和传感器一控制器端存在Markov随机延迟的情况下控制与通信协同设计问题,提出了系统均方稳定的条件。采用静态通信序列,使通信序列和控制器可以分别设计,应用V-K迭代算法设计最优周期控制增益。仿真算例验证了系统在所设计的最优控制器下达到均方稳定。     

Circadian variation in urinary melatonin in clinically healthy women in Japan and the United States of America

Summary Urinary melatonin excretion is lower in East-Asian (Japanese) than in North-American (whites of mixed ethnic origin) women. Moreover, a statistically significant circadian rhythm is demonstrated by population-mean cosinor in the data pool from both groups of women. Furthermore, statistical significance characterizes interactions of effects from geographic differences (between ethnic groups) with temporal factors. Such spatio-temporal interactions await further scrutiny with a view inter alia of carcinogenesis as it is influenced by a spectrum of intermodulating rhythms.Supported by U.S. Public Health Service (5-K6-GM-13981-17), National Cancer Institute (1R01-CA-14445-05 and N01-CP-5-5702), National Institute of Occupational Safety and Health (OH-00631-01), National Institute of Aging (AG-00158), Environmental Protection Agency (R804513-01-0), Swedish Medical Research Council grant 3371 and the St Paul Ramsey Medical Research and Education Foundation. R.B. Sothern and Jung-Keun Lee, Scientists, Chronobiology Laboratories, University of Minnesota provided valuable help.     

具有Markov延迟的网络化控制系统控制与通信协同设计

由于网络化控制系统分析与设计的复杂性,其控制与通信协同设计问题一直没有得到解决.该文讨论了一类离散线性时不变网络化控制系统在服从介质访问约束和传感器-控制器端存在Markov随机延迟的情况下控制与通信协同设计问题,提出了系统均方稳定的条件.采用静态通信序列,使通信序列和控制器可以分别设计,应用V-K迭代算法设计最优周期控制增益.仿真算例验证了系统在所设计的最优控制器下达到均方稳定.     

Localization of type 1 diabetes susceptibility to the MHC class I genes HLA-B and HLA-A

The major histocompatibility complex (MHC) on chromosome 6 is associated with susceptibility to more common diseases than any other region of the human genome, including almost all disorders classified as autoimmune. In type 1 diabetes the major genetic susceptibility determinants have been mapped to the MHC class II genes HLA-DQB1 and HLA-DRB1 (refs 1-3), but these genes cannot completely explain the association between type 1 diabetes and the MHC region. Owing to the region's extreme gene density, the multiplicity of disease-associated alleles, strong associations between alleles, limited genotyping capability, and inadequate statistical approaches and sample sizes, which, and how many, loci within the MHC determine susceptibility remains unclear. Here, in several large type 1 diabetes data sets, we analyse a combined total of 1,729 polymorphisms, and apply statistical methods-recursive partitioning and regression-to pinpoint disease susceptibility to the MHC class I genes HLA-B and HLA-A (risk ratios >1.5; P(combined) = 2.01 x 10(-19) and 2.35 x 10(-13), respectively) in addition to the established associations of the MHC class II genes. Other loci with smaller and/or rarer effects might also be involved, but to find these, future searches must take into account both the HLA class II and class I genes and use even larger samples. Taken together with previous studies, we conclude that MHC-class-I-mediated events, principally involving HLA-B*39, contribute to the aetiology of type 1 diabetes.     

Cytotoxic effect of a xenogeneic antiserum on bone marrow cells from normal or sublethally irradiated mice

Résumé Un antisérum dirigé contre les tissus embryonnaires de la souris contient des anticorps capables de détruire sélectivement une population de cellules présente dans la moelle qui régénère après une irradiation sublétale. On peut supposer que la population détruite correspond à un type particulier de cellules lymphoïdes immatures (cellules X) qui caractérise la régénération médullaire de la souris irradiée.     

Zur Methodik der Gefrierschnitt-Mikroautoradiographie

Summary A microautoradiographic technique for frozen sections is described. The method makes it possible to follow the distribution of inhaled radon in the organism with high degree of accuracy. After inhaling radon, the mice were killed and stored in liquid air (freezing method ofRajewsky ⁹). The organ sections (5µ thick) were prepared by means of a freezing microtome in the Kryostat. A thin fixing and protecting layer of chromic alum gelatine was placed between the tissue-sections and the photographic emulsion. The exposure took place in an atmosphere of nitrogen.     

脂肪酶催化制备丁酸乙酯的研究

利用脂肪酶BSL2作为催化剂,在有机介质中催化合成丁酸乙酯.考察了反应温度、底物浓度、底物摩尔比、反应介质和初始水活度等反应条件对酶促合成丁酸乙酯的影响.试验结果表明:以正己烷为溶剂,初始水活度为0.33,加酶量为100 mg,丁酸浓度为40 mM,底物摩尔比(丁酸/乙醇)为1∶1.5,在40℃条件下振荡反应30 h,合成丁酸乙酯的的转化率可达到94.8%.