Variations in mental performance under moderate cold stress

Effects of moderate cold stress on reasoning ability, associative learning and critical flicker frequncy of Indian subjects were studied by exposing them to 25C,. 20C, 15C and 10C for three hours. A second set of experiments was also conducted to confirm the conclusions of the first by using the same temperatures and duration of exposure. However, not only the sample used in the second case was larger and different but also the mental functions tested were numerical ability, running memory and mental alertness. It has been concluded that there is a significant impairment of simple cognitive functions at 15C which is 10C lower than their most comfortable temperature of 25C.     

Birth weight from pregnancies dated by ultrasonography in a multicultural British population.

OBJECTIVE--To produce standard curves of birth weight according to gestational age validated by ultrasonography in the British population, with particular reference to the effects of ethnic origin. DESIGN--Retrospective analysis of computerised obstetric database. SETTING--Three large maternity units associated with Nottingham University with over 16,000 deliveries a year. PATIENTS--41,718 women with ultrasound dated singleton pregnancies and delivery between 168 and 300 days'' gestation. MAIN OUTCOME MEASURES--Length of gestation, ethnic origin, parity, maternal height and weight at booking, smoking during pregnancy; the effect of these variables on birth weight. RESULTS--Birth weights from ultrasound dated pregnancies have a higher population mean and show less flattening of the birthweight curve at term than those of pregnancies dated from menstrual history. Significant differences were observed in mean birth weights of babies of mothers of European origin (3357 g), of Afro-Caribbean origin (3173 g), and from the Indian subcontinent (3096 g). There were also significant interethnic differences in length of gestation, parity, maternal height, booking weight, and smoking habit which affected birth weight. The ethnic differences in birth weight were even greater when the effect of smoking was excluded. CONCLUSIONS--Birthweight standards require precise dating of pregnancy and should describe the population from which they were derived. In a heterogeneous maternity population the accurate assessment of an individual baby''s weight needs to take the factors which affect birthweight standards into consideration.     

Evidence for asthma susceptibility genes on chromosome 11 in an African-American population

Initial genome-wide scan data provided suggestive evidence for linkage of the asthma phenotype in African-American (AA), but not Caucasian, families to chromosome 11q markers (peak at D11S1985; LOD=2). To refine this region, mapping analysis of 91 AA families (51 multiplex families and 40 asthmatic case-parent trios) was performed with an additional 17 markers flanking the initial peak linkage marker. Multipoint analyses of the 51 multiplex families yielded significant evidence of linkage with a peak non-parametric linkage score of 4.38 at marker D11S1337 (map position 68.6 cM). Furthermore, family-based association and transmission disequilibrium tests conducted on all 91 families showed significant evidence of linkage in the presence of disequilibrium for several individual markers in this region. A putative susceptibility locus was estimated to be at map position 70.8 cM with a confidence interval spanning the linkage peak. Evidence from both linkage and association analyses suggest that this region of chromosome 11 contains one or more susceptibility genes for asthma in these AA families.     

The distribution of long range admixture linkage disequilibrium in an African-American population

OBJECTIVES: To better understand the effect of admixture on long range linkage disequilibrium (LD), we characterized extended LD in gene-rich regions of an African-American population. METHODS: Approximately 290 cM of chromosomes 1, 3, 6, 11-17, 20 and 22 were scanned using 109 polymorphic microsatellite markers spaced an average of 3 cM apart. Disequilibrium between loci (D') was based on maximum-likelihood estimates of haplotype frequencies computed for 200 unrelated African Americans. RESULTS: Mean D' values were highest on chromosomes 6p23-p21.3 (D' = 0.33) and 15p22.2-p25.3 (D' = 0.34), and lowest on chromosome 12p11.2-q14 (D' = 0.21). Overall, the variance in LD among chromosomes accounted for approximately two-thirds of the total LD variance. Of the 434 locus pairs spaced between 0.3 and 38.7 cM apart, there was no detectable correlation between LD and recombination distance and a weak negative correlation between LD and physical distance (r(s) = -0.12; p = 0.031). For the 192 intrachromosomal locus pairs where allele frequency data were available from the Centre d'Etude du Polymorphisme humain (CEPH), we found a statistically significant positive correlation between LD and the allelic frequency differences (delta) between the African-American study population and Caucasian reference CEPH population (r(s) = 0.53; p < 0.0001). The correlation between LD and both recombination and physical distance was markedly increased for locus pairs with high delta levels. CONCLUSIONS: Our results suggest that recent Caucasian admixture maintains a high level of long range LD in African Americans on a genomic scale, and selected markers with large African American/Caucasian delta levels may be useful in association studies.     

Birth weight and childhood onset type 1 diabetes: population based cohort study

ObjectiveTo assess the associations between birth weight or gestational age and risk of type 1 diabetes.DesignPopulation based cohort study by record linkage of the medical birth registry and the National Childhood Diabetes Registry.SettingTwo national registries in Norway.ParticipantsAll live births in Norway between 1974 and 1998 (1 382 602 individuals) contributed a maximum of 15 years of observation, a total of 8 184 994 person years of observation in the period 1989 to 1998. 1824 children with type 1 diabetes were diagnosed between 1989 and 1998.ResultsThe incidence rate of type 1 diabetes increased almost linearly with birth weight. The rate ratio for children with birth weights 4500 g or more compared with those with birth weights less than 2000 g was 2.21 (95% confidence interval 1.24 to 3.94), test for trend P=0.0001. There was no significant association between gestational age and type 1 diabetes. The results persisted after adjustment for maternal diabetes and other potential confounders.ConclusionThere is a relatively weak but significant association between birth weight and increased risk of type 1 diabetes consistent over a wide range of birth weights.

What is already known on this topic

Results of case-control studies of birth weight and risk of type 1 diabetes have been inconsistentIt is possible that a relatively weak association exists, and large studies are needed to find out if this is the case

What this study adds

This is the largest study of birth weight and type 1 diabetes published to date, and the first one to use a cohort designThe incidence of type 1 diabetes increased almost linearly with increasing birth weight over a wide range of birth weights, independent of gestational age, maternal diabetes, and other potential confoundersThe trend was highly significant, but the increment in risk with increasing birth weight was still relatively low     

Photosynthetic electron transport and proton flux under moderate heat stress

Moderate heat stress has been reported to increase PSI cyclic electron flow (CEF). We subjected leaves of Arabidopsis (Arabidopsis thaliana) mutants disrupted in the regulation of one or the other pathway of CEF flow—crr2 (chlororespiratory reduction, deficient in regulation of chloroplast NAD(P)H dehydrogenase-dependent CEF) and pgr5 (proton gradient regulation, proposed to have reduced efficiency of antimycin-A-sensitive-CEF regulation) to moderate heat stress. Light-adapted leaves were switched from 23 to 40°C in 2 min. Gas exchange, chlorophyll fluorescence, the electrochromic shift (ECS), and P700 were measured. Photosynthesis of crr2 and pgr5 was more sensitive to heat and had less ability to recover than the genetic background gl. The proton conductance in light was increased by heat and it was twice as much in pgr5, which had much smaller light-induced proton motive force. We confirmed that P700 becomes more reduced at high temperature and show that, in contrast, the proportion of PSII open centers (with Q _A oxidized) increases. The two mutants had much slower P700⁺ reduction rate during and after heat than gl. The proportion of light absorbed by PSI versus PSII was increased in gl and crr2 during and after heat treatment, but not in pgr5. We propose that heat alters the redox balance away from PSII and toward PSI and that the regulation of CEF helps photosynthesis tolerate heat stress.     

Induced anti-oxidant activity in soybean alleviates oxidative stress under moderate boron toxicity

The effect of B toxicity on antioxidant responses of soybean (Glycine max) cv. Athow was investigated by growing plants for 43 days at 0.2 (control), 2 and 12 mg B kg^?1. At the end of the treatment period, shoot growth, lipid peroxidation level, the activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR), and their isoenzymes in leaves were measured. Boron concentration in leaves was significantly increased by the increasing levels of B treatment from 43 to 522 mg kg^?1, and shoot dry matter was depressed at 12 mg B kg^?1. Significant increases in SOD, CAT, and APX activities were determined in leaves under 12 mg B kg^?1; however, GR activities were decreased while POX activity was unchanged. Increased enzymic antioxidant activity arose from a combination of newly formed isoenzymes and activation of existing isoenzymes. By contrast, SOD and GR activities were decreased by 2 mg B kg^?1 concentration as compared to the control groups while POX activity was increased and the activity of CAT did not change. Malondialdehyde content increased under 2 mg B kg^?1 but decreased under 12 mg B kg^?1. These results suggest that higher antioxidant activity observed under 12 than at 2 mg B kg^?1 provided higher free radical-scavenging capacity, and thus a lower level of lipid peroxidation in Athow. While the induction of increased antioxidant activity was related to internal boron levels, the signaling and coordination of responses remain unclear.     

Replication of an African-American GWAS on blood pressure and hypertension in the Korean population

Hypertension is a complex disease that is caused by the interaction of multiple genetic and environmental risk factors, affecting 30% adult in industrialized countries. The identification of genetic factors that impact one’s predisposition to hypertension and its progression is an ongoing challenge. A genome-wide association study of African-Americans, who have one of the highest rates of hypertension in the world, was reported. We replicated the GWAS results in 8842 unrelated Koreans. Fifteen of the 30 reported SNPs were analyzed for their association with blood pressure and hypertension. Linear regression was used to analyze blood pressure as a quantitative trait in 7551 subjects, and a case-control study was performed using 1968 hypertensive cases and 4452 normotensive controls by logistic regression analysis. The quantitative trait study demonstrated a moderate association of 2 SNPs, rs9301196 (p=4.9×10^?3 for diastolic blood pressure) and rs2823756 (p=0.04 for systolic blood pressure), which were also associated with hypertension (p=0.042 and p=6.3×10^?3, respectively). Further, 3 SNPs were associated with hypertension (p=0.042 for rs7902529, p=0.027 for rs10135446, and p=0.01 for rs4613079) but not with blood pressure. Based on the moderate association signals and the low proportion of positive signals, this cross validation between African-Americans and Asians suggests that association studies of blood pressure traits require a larger number of subjects and a more refined design.     

Birth weight and cognitive function in the British 1946 birth cohort: longitudinal population based study

Objective: To examine the association between birth weight and cognitive function in the normal population. Design: A longitudinal, population based, birth cohort study. Participants: 3900 males and females born in 1946. Main outcome measures: Cognitive function from childhood to middle life (measured at ages 8, 11, 15, 26, and 43 years). Results: Birth weight was significantly and positively associated with cognitive ability at age 8 (with an estimated standard deviation score of 0.44 (95% confidence interval 0.28 to 0.59)) between the lowest and highest birthweight categories after sex, father's social class, mother's education, and birth order were controlled for. This association was evident across the normal birthweight range (>2.5 kg) and so was not accounted for exclusively by low birth weight. The association was also observed at ages 11, 15, and 26, and weakly at age 43, although these associations were dependent on the association at age 8. Birth weight was also associated with education, with those of higher birth weight more likely to have achieved higher qualifications, and this effect was accounted for partly by cognitive function at age 8. Conclusions: Birth weight was associated with cognitive ability at age 8 in the general population, and in the normal birthweight range. The effect at this age largely explains associations between birth weight and cognitive function at subsequent ages. Similarly, the association between birth weight and education was accounted for partly by earlier cognitive scores.     

Birth weight and natural selection: an example of selection relaxation in man

Differential mortality as a function of birth weight was studied in Japan in the years 1969, 1974 and 1984. During the 15-year interval of observation a progressive equalization of mortality in the birth weight classes near the mean was found both for perinatal mortality as a whole and for its two components, stillbirth and mortality within the 1st week of life. The relaxation of selection on this metric trait is confirmed by the analysis of the variation over time of intensity of selection. A comparison of the Japanese population with other populations so far studied is also presented.     

Birth and breeding cyclicity in an outdoor living stumptail macaque (Macaca arctoides) group

Birth records were examined for a group of 56 Stumptail macaques that lived in an half-acre outdoor enclosure from 1971 to 1974. Approximate conception times for 33 offspring were calculated and two graphs, one for births and the other one for fertile matings were constructed. Although births occurred throughout the year, 48.5% or these took place between June and September with a peak in July and August (39.4%). Two secondary peaks, one between February and April (27.3%) and the other in November (12.1%) were noted. Fertile matings also took place throughout the year but 56.6% were concentrated between January and June with a peak in January and February (30.3%). A secondary peak was observed for September (12.1%). The data show that no discrete seasonality in matings and births is present forMacaca arctoides but that an unusual pattern consisting of three peaks throughout the year, for births, may be typical of the species. The data are compared with data on the taxonomically close Japanese macaque and a striking dissimilarity is found. While thefuscata macaque has discrete breeding seasonality, thearctoides macaque breeds and gives birth throughout the year and its pattern is more similar to that of the distantly related Crab-eating macaque. This work was supported by grants from Behavioral Sciences Foundation and by NSF-#GB-42235.     

H2O2应激条件下的活性酵母细胞衍生物的研究

对过氧化氢（H2O2）应激条件下产生的活性酵母衍生物（Live Yeast Cell Derivative,LYCD）进行了研究,结果表明：LYCD对细胞具有明显的促呼吸作用,其作用大小与制备LYCD过程中所加入的H2O2的刺激强度有关。另外,对LYCD中两种重要的抗氧剂-还原型谷胶甘肽（GSH）和超氧化物歧化酶（SOD）的测定分析结果显示：在H2O2的作用下,应激反应发生15min时,LY-CD中SOD的比活力最强,发生30min时,GSH的含量最高,不同的应激产物有各自产生的最佳时间。     

Responses of dry weight growth under SO2 stress in an SO2-tolerant plant,Polygonum cuspidatum

The effects of exposure to 0.5–0.7 ppm SO₂ for about one month on the dry weight growth and net photosynthesis ofPolygonum cuspidatum were investigate. Furthermore, the carbon and nitrogen concentrations in each plant organ were measured. The results obtained showed no significant decrease in the total dry weight of SO₂-treated plants in comparison with controls. On the other hand, the leaf area (LA) and/or leaf dry weight of SO₂-treated plants were increased, and the root dry weight (RW) was decreased, in comparison with controls. The leaf carbon assimilation rate (CAR) in SO₂-treated plants was slightly decreased in spite of a clear decrease in net photosynthesis, and the value of (SW+RW)/LA (SW stem dry weight) was decreased in comparison with controls, thus minimizing the reduction in CAR. Furthermore, the ratio of total leaf carbon absorption (leaf area x CAR) to total root nitrogen absorption (root dry weight x nitrogen assimilation rate) in SO₂-treated plants was similar to that in controls. From these results, it can be concluded that an increase in leaf area and/or leaf dry weight and a decrease in root dry weight inP. cuspidatum under SO₂ stress may be induced in order to compensate for the decrease in CAR and to maintain the ratio of total leaf carbon absorption to total root nitrogen absorption in the early stage of vegetative growth.