电转化法转化钝顶螺旋藻转化条件的研究

确定了电转化法转化钝项螺旋藻S6-4的转化条件。无论受体是藻丝还是单细胞／藻丝段，钝项螺旋藻S6-4在对数生长期内，半致死电场强度无显著差别。实验表明以对数中期的螺旋藻用于转化为宜。当脉冲时间是5．0ms时，藻丝受体和单细胞／藻丝段受体的半致死电场强度分别是3．75—5．0kV／cm和3．1—4．4kV／cm，而电击缓冲液分别是1．0mmol／L HEPES(pH7．5)缓冲液和含有0．5mol／L蔗糖的1．0mmol／L HEP—ES(pH7．5)缓冲液。本文的研究结果为螺旋藻转化及外源基因表达提供了实验基础。     

Hyperdynamic circulation of cirrhotic rats: role of substance P and its relationship to nitric oxide

BACKGROUND: It has been suggested that excessive formation of nitric oxide (NO) is responsible for the hyperdynamic circulation observed in portal hypertension. Substance P is a neuropeptide partly cleared by the liver and causes vasodilatation through the activation of the endothelial NO pathway. However, there are no previously published data concerning the plasma level of substance P in cirrhotic rats and its relationship to NO. METHODS: Plasma concentrations of substance P and nitrate/nitrite (an index of NO production) were determined in control rats and cirrhotic rats with or without ascites using an enzyme-linked immununosorbent assay and a colorimetric assay, respectively. In addition, systemic and portal hemodynamics were evaluated by a thermodilution technique and catheterization. RESULTS: Cirrhotic rats with and without ascites had a lower systemic vascular resistance (2.6 +/- 0.2 and 3.9 +/- 0.4 mmHg ml(-1) x min x 100 g body weight, respectively) and higher portal pressure (14.6 +/- 0.6 and 11.3 +/- 1.8 mmHg) than control rats (6.5 +/- 0.3 mmHg x ml(-1) x min x 100 g BW and 6.8 +/- 0.2 mmHg, respectively, P < 0.05), and cirrhotic rats with ascites had the lowest systemic vascular resistance. Plasma levels of nitrate/nitrite progressively increased in relation to the severity of liver dysfunction (control rats, 2.7 +/- 0.5 nmol/ml; cirrhotic rats without ascites, 5.6 +/- 1.3 nmol/ml; cirrhotic rats with ascites, 8.3 +/- 2.2 nmol/ml; P < 0.05). Cirrhotic rats with ascites displayed higher plasma values of substance P (57.7 +/- 5.9 pg/ml) than cirrhotic rats without ascites (37.9 +/- 3.1 pg/ml, P < 0.05) and control rats (30.1 +/- 1.0 pg/ml, P < 0.05). There was no significant difference in plasma substance P values between control rats and cirrhotic rats without ascites (P > 0.05). No correlation was found between plasma levels of substance P and nitrate/nitrite (r = 0.318, P > 0.05). CONCLUSIONS: Excessive formation of NO may be responsible, at least partly, for the hemodynamic derangements in cirrhosis. Although substance P may not participate in the initiation of a hyperdynamic circulation in cirrhosis, it may contribute to the maintenance of the hyperdynamic circulation observed in cirrhotic rats with ascites.     

离子静电水处理技术在循环冷却水中的应用

简要介绍了离子静电水处理技术杀菌、灭藻、防垢阻垢的机理，及在循环冷却水系统中的应用情况。     

GaAs亚微米自对准工艺技术研究

总结了在５０ｍｍＧａＡｓ圆片上实现自对准介质膜隔离等平面工艺技术的研究，着重描述了离子注入、自对准亚微米难熔栅制备、钝化介质膜生长、干法刻蚀、电阻和电容制备等关键工艺的研究结果。这套工艺的均匀性、重复性好，在５０ｍｍＧａＡｓ圆片上获得了满意的成品率。采用这套工艺已成功地研制出多种性能良好的ＧａＡｓＩＣ和ＧａＡｓ功率ＭＥＳＦＥＴ，证明国家自然科学基金委员会这一重大课题的选择对发展我国ＧａＡｓＩＣ确实具有重大意义。     

Nutrient intakes of adolescents with phenylketonuria and infants and children with maple syrup urine disease on semisynthetic diets

Adequacy of nutrient intakes of adolescents with and without phenylketonuria (PKU) and infants and children with and without maple syrup urine disease (MSUD) were assessed using 3-day diet records sorted by disease and by age of the subject. Mean intakes of all nutrients were greater than two-thirds of the Recommended Dietary Allowances (RDA) or Estimated Safe and Adequate Daily Dietary Intakes (ESADDI) for all adolescents studied, with the exception of selenium (Se) in PKU adolescents, which averaged 27.8 micrograms. For adolescents with PKU, > 50% of the RDA or ESADDI for all nutrients was provided by elemental or modified protein hydrolysate medical foods, except for vitamin A in children aged 11-15 years and Se in children 11-18 years. Mean nutrient intakes of all infants and children were greater than two-thirds of the RDA or ESADDI for all nutrients except Se in MSUD children aged 1-11 years, where intakes ranged from 6.4 to 13.2 micrograms (21-66% of the RDA). The medical foods provided for most of the RDA and ESADDI recommendations, with the exception of Se in MSUD children.     

Homozygous parent affected sib pair method for detecting disease predisposing variants: application to insulin dependent diabetes mellitus

For complex genetic diseases involving incomplete penetrance, genetic heterogeneity, and multiple disease genes, it is often difficult to determine the molecular variant(s) responsible for the disease pathogenesis. Linkage and association studies may help identify genetic regions and molecular variants suspected of being directly responsible for disease predisposition or protection, but, especially for complex diseases, they are less useful for determining when a predisposing molecular variant has been identified. In this paper, we expand upon the simple concept that if a genetic factor predisposing to disease has been fully identified, then a parent homozygous for this factor should transmit either of his/her copies at random to any affected children. Closely linked markers are used to determine identity by descent values in affected sib pairs from a parent homozygous for a putative disease predisposing factor. The expected deviation of haplotype sharing from 50%, when not all haplotypes carrying this factor are in fact equally predisposing, has been algebraically determined for a single locus general disease model. Equations to determine expected sharing for multiple disease alleles or multiple disease locus models have been formulated. The recessive case is in practice limiting and therefore can be used to estimate the maximum proportion of putative susceptibility haplotypes which are in fact predisposing to disease when the mode of inheritance of a disease is unknown. This method has been applied to 27 DR3/DR3 parents and 50 DR4/DR4 parents who have at least 2 children affected with insulin dependent diabetes mellitus (IDDM). The transmission of both DR3 and DR4 haplotypes is statistically different from 50% (P < 0.05 and P < 0.001, respectively). An upper estimate for the proportion of DR3 haplotypes associated with a high IDDM susceptibility is 49%, and for DR4 haplotypes 38%. Our results show that the joint presence of non-Asp at DQ beta position 57 and Arg at DQ alpha position 52, which has been proposed as a strong IDDM predisposing factor, is insufficient to explain the HLA component of IDDM predisposition.     

Cigarette smoking and submaximal exercise test duration in a biracial population of young adults: the CARDIA study

Symptom-limited, graded exercise treadmill testing was performed by 4,968 white and black adults, ages 18-30 yr, during the baseline examination for the Coronary Artery Risk Development in Young Adults (CARDIA) study. Compared with nonsmokers, the mean exercise test duration of smokers was 29-64 s shorter depending on race/gender group (all P < 0.001), but mean duration to heart rate 130 (beats.min-1) ranged from 20-50 s longer (P < 0.05). In each race/gender group, test duration to heart rates up to 150 was 15-35 s longer (P < 0.05) in smokers than in nonsmokers after adjustment for age, sum of skinfolds, hemoglobin, and physical activity score. The mean maximum heart rate was lower in smokers than in nonsmokers (difference ranging from 6.7 beats.min-1 in white men to 11.2 beats.min-1 lower in black women, P < 0.001), although maximum rating of perceived exertion was nearly identical in smokers and nonsmokers. Chronic smoking appears to blunt the heart rate response to exercise, so that exercise duration to submaximal heart rates is increased even though maximal performance is impaired. This may result from downloading of beta-receptors caused by smoking. Smoking status should be considered in the evaluation of physical fitness data utilizing submaximal test protocols, or else the fitness of smokers relative to nonsmokers is likely to be overestimated.     

太钢电弧炉上应用四星接法MOA的必要性

分析了太钢电弧炉变压器高压侧相间过电压的产生原因，比较了用于限制过电压的避雷器的两种接法．结论是用四垦接法ＭＯＡ限制过电压的效果较显著．