Cognitive ability and academic achievement in the Colorado Adoption Project: A multivariate genetic analysis of parent-offspring and sibling data

To test the hypothesis that the etiology of covariation among measures of cognitive ability and academic achievement is due at least in part to shared genetic influences, data from 198 adoptive and 220 nonadoptive families participating in the Colorado Adoption Project were subjected to multivariate behavioral genetic analyses. Data on measures of cognitive ability (verbal comprehension and perceptual organization) and academic achievement (reading recognition and mathematics achievement) from related and unrelated sibling pairs tested at age 7, as well as from adoptive and nonadoptive parents, were analyzed. Phenotypic analyses confirmed previous findings of moderate correlations among measures of cognitive ability and achievement, averaging about .35. Although 54% of the covariation between reading and mathematics achievement was due to influences shared with verbal ability, a significant proportion of this covariation was independent of the cognitive ability measures. Heritabilities for the various measures were moderate, ranging from .21 to .37. Moreover, genetic influences accounted for 33–64% of their phenotypic covariation; for example, 33–60% of the observed correlations between verbal comprehension and the achievement measures, 64% of those between perceptual organization and the achievement measures, and 63% of that between reading recognition and mathematics achievement were due to shared genetic influences. Similar to the results of the phenotypic analysis, nearly half of the genetic covariance between reading and mathematics achievement was independent of cognitive ability. Their remaining covariance was due primarily to nonshared environmental influences.     

How the ability of bacteria to inactivate natural antiinfectious resistance factors affects their resistance to the bactericidal action of the blood (Serum)

A relationship is found between the resistance ofEscherichia coli, Staphylococcus aureus, andStaphylococcus epidermidis to human serum and whole blood and their ability to inactivate the factors of natural antiinfectious resistance (lysozyme, complement, immunoglobulins, and a bactericidal fraction of leukocytic interferon). Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 174–176, February, 1996     

Mating ability in laboratory-adapted and field-derivedDrosophila melanogaster: The stress of domestication

Mating ability differences between flies of different alcohol dehydrogenase (Adh) genotypes have been assessed in the temperature range 15 to 29°C for laboratory-adapted and field-derivedDrosophila melanogaster. Significant differences amongAdh genotypes were detected principally for the laboratory-adapted strains due to departures from random mating associated with heterozygote superiority at the relatively extreme temperature of 29°C, although mating ability differences could not be attributed directly to theAdh locus. The difference between the laboratory and the field populations can be explained by the effects of genetic back-ground manifested in the form of fitness differences, being enhanced for the laboratory-adapted flies as a consequence of the stress of laboratory culture. In contrast with larval survival and development time, laboratory and field flies do not differe appreciably in their overall abilities to obtain mates, which indicates that mating ability is a direct fitness character not greatly affected by laboratory culture. It follows that direct fitness traits are the least amenable to change under domestication.     

Evaluation of in vivo and in vitro repopulation assays for murine haemopoietic stem cells

Three assays to determine the repopulation potential of stem cells in murine bone marrow grafts were evaluated on their reliability with regard to the ranges in graft size. In vivo, marrow repopulating ability, as calculated from the number of in vitro clonable progenitors (colony-forming units in culture, CFU-C) generated by the graft in the femur of an irradiated recipient, appeared to be independent of the input over a wide range of cell numbers grafted. A second assay, erythroid repopulating ability is a measure of the number of new reticulocytes or erythrocytes in the blood generated by the graft, and significantly underestimates stem cell activity of the graft. The third assay measures the long-term repopulating ability of bone marrow cells in vitro on pre-established stromal cell layers by determination of the number of CFU-C produced in these cultures. Calculations of short-term in vitro repopulating ability, done from measurements of the production of non-adherent CFU-C in the first week of culture, appeared to be independent of cell input. Long-term in vitro repopulating potential, measured by the CFU-C content of the adherent layer at 4 weeks, is also independent of the numbers of cell input.     

Genetic Structure of Spatial and Verbal Working Memory

Working memory (WM) encompasses both short-term memory (storage) and executive functions that play an essential role in all forms of cognition. In this study, the genetic structure of storage and executive functions engaged in both a spatial and verbal WM span task is investigated using a twin sample. The sample consists of 143 monozygotic (MZ) and 93 dizygotic (DZ) Japanese twin pairs, ages 16 to 29 years. In 155 (87 MZ, 62 DZ) of these pairs, cognitive ability scores from the Kyodai Japanese IQ test are also obtained. The phenotypic relationship between WM and cognitive ability is confirmed (r = 0.26–0.44). Individual differences in WM storage and executive functions are found to be significantly influenced by genes, with heritability estimates all moderately high (43%–49%), and estimates for cognitive ability comparable to previous studies (65%). A large part of the genetic variance in storage and executive functions in both spatial and verbal modalities is due to a common genetic factor that accounts for 11% to 43% of the variance. In the reduced sample, this common genetic factor accounts for 64% and 26% of the variance in spatial and verbal cognitive ability, respectively. Additional genetic variance in WM (7%–30%) is due to modality specific factors (spatial and verbal) and a storage specific factor that may be particularly important for the verbal modality. None of the variance in cognitive ability is accounted for by the modality and storage genetic factors, suggesting these may be specific to WM.     

Diurnal variations of serum erythropoietin at sea level and altitude

This study tested the hypothesis that the diurnal variations of serum-erythropoietin concentration (serum-EPO) observed in normoxia also exist in hypoxia. The study also attempted to investigate the regulation of EPO production during sustained hypoxia. Nine subjects were investigated at sea level and during 4 days at an altitude of 4350 m. Median sea level serum-EPO concentration was 6 (range 6–13) U·l^–1. Serum-EPO concentration increased after 18 and 42 h at altitude, [58 (range 39–240) and 54 (range 36–340) U·l^–1, respectively], and then decreased after 64 and 88 h at altitude [34 (range 18–290) and 31 (range 17–104) U·l^–1, respectively]. These changes of serum-EPO concentration were correlated to the changes in arterial blood oxygen saturation (r = –0.60,P = 0.0009), pH (r = 0.67,P = 0.003), and in-vivo venous blood oxygen half saturation tension (r = –0.68,P = 0.004) but not to the changes in 2, 3 diphosphoglycerate. After 64 h at altitude, six of the nine subjects had down-regulated their serum-EPO concentrations so that median values were three times above those at sea level. These six subjects had significant diurnal variations of serum-EPO concentration at sea level; the nadir occurred between 0800–1600 hours [6 (range 4–13) U·l^–1], and peak concentrations occurred at 0400 hours [9 (range 8–14) U·l^–1,P = 0.02]. After 64 h at altitude, the subjects had significant diurnal variations of serum-EPO concentration; the nadir occurred at 1600 hours [20 (range 16–26) U·l^–1], and peak concentrations occurred at 0400 hours [31 (range 20–38) U·l^–1,P = 0.02]. This study demonstrated diurnal variations of serum-EPO concentration in normoxia and hypoxia, with comparable time courses of median values. The results also suggested that EPO production at altitude is influenced by changes in pH and haemoglobin oxygen affinity.     

New evidence from magnetic resonance imaging of brain changes after climbs at extreme altitude

The aim of the present study was to look for anatomical changes in climbers' brains, using magnetic resonance imaging (MRI), after extremely high-altitude climbs and to relate them to possible associated risk factors. Clinical history, neurological examinations and MRI were carried out on a group of nine climbers before and after climbing to over 7500 m without the use of supplementary oxygen. None of the subjects showed any neurological dysfunctions. In five climbers MRI abnormalities (high signal areas, cortical atrophy) were observed before the expedition. After the descent, two of them showed new high intensity signal areas recorded by MRI. Both subjects suffered severe neurological symptoms during the climb. The present study suggested that the brain changes observed by MRI could be related to the severity of clinical events at high altitude. However, we do not know the exact meaning of such MRI findings or the reason for their location, predominantly in posterior regions of the brain. The new evidence that a high percentage of climbers show MRI brain abnormalities, and especially the appearance of changes after the ascent, reinforces the possibility of a potential neurological risk in high-altitude climbing.     

Changes in performance,maximal oxygen uptake and maximal accumulated oxygen deficit after 5, 10 and 15 days of live high:train low altitude exposure

Nineteen well-trained cyclists (14 males and 5 females, mean initial V˙O_2max 62.3 ml kg^–1 min^–1) completed a multistage cycle ergometer test to determine maximal mean power output in 4 min (MMPO_4min), maximal oxygen uptake (V˙O_2max) and maximal accumulated oxygen deficit (MAOD). The athletes were divided into three groups, each of which completed 5, 10 or 15 days of both a control condition (C) and live high:train low altitude exposure (LHTL). The C groups lived and trained at the ambient altitude of 610 m. The LHTL groups spent 8–10 h night^–1 in normobaric hypoxia at a simulated altitude of 2,650 m, and trained at the ambient altitude of 610 m. The changes to MMPO_4min, V˙O_2max and MAOD in response to LHTL altitude exposure were not significantly different for the 5-, 10- and 15-day treatment periods. For the pooled data from all three treatment periods, there were significant increases in MMPO_4min [mean (SD) 5.15 (0.83) W kg^–1 vs 5.34 (0.78) W kg^–1] and MAOD [50.1 (14.2) ml kg^–1 vs 54.9 (13.1) ml kg^–1] in the LHTL athletes between pre- and post-altitude exposure. There were no significant changes in MMPO_4min [5.09 (0.76) W kg^–1 vs 5.16 (0.86) W kg^–1] or MAOD [50.5 (14.1) ml kg^–1 vs 49.1 (13.0) ml kg^–1] in the C athletes over the corresponding period. There were significant increases in V˙O_2max in the athletes during both the LHTL [63.2 (9.0) ml kg^–1 min^–1 vs 64.1 (9.0) ml kg^–1 min^–1] and C [62.0 (8.6) ml kg^–1 min^–1 vs 63.4 (9.2) ml kg^–1 min^–1] conditions. In these athletes, there was no difference in the impact of 5, 10 or 15 days of LHTL on the increases observed in MMPO_4min, V˙O_2max or MAOD; and LHTL increased MMPO_4min and MAOD more than training at low altitude alone. Electronic Publication     

中国健康人两项血液流变学参考值与海拔高度的关系

为制定中国健康成年男性血沉参考值(温氏法)和中老年女性红细胞压积参考值(温氏法)的统一标准提供科学依据,本文研究了中国226个单位测定的22707例健康成年男性的血沉参考值(温氏法)和312个单位测定的15608例健康中老年女性的红细胞压积参考值(温氏法),并对其与海拔高度的关系进行了研究,发现随着海拔高度的逐渐增大,健康成年男性血沉参考值(温氏法)在逐渐的减小,而健康中老年女性红细胞压积参考值(温氏法)在逐渐的增大,相关性都很显著。用回归分析的方法推导出了二个一元回归方程。如果知道了中国某地的海拔高度,就可以用这二个回归方程,估算这个地区的健康成年男性血沉参考值(温氏法)和健康中老年女性红细胞压积参考值(温氏法)。     

高原红细胞增多症患者血浆组织因子水平

目的:通过测定高原低氧环境中，不同人群血浆组织因子水平，探讨其在高原红细胞增多症病理变化中的作用。 方法:采用固相双抗体夹心酶联免疫吸附法测定高原红细胞增多症患者、高原世居健康人群及不同居住时间的高原移居健康人群血浆组织因子浓度，与世居西宁健康人群对照，进行方差分析和相关分析比较研究。 结果:高原红细胞增多症组血浆组织因子浓度明显高于对照组（P<0.01），并与高原世居及移居各组比较均有显著差异（P<0.01）；高原红细胞增多症组血浆组织因子浓度与血红蛋白水平呈正相关（r=0.608, P<0.01），与血小板计数呈负相关（r=-0.862, P<0.01）。 结论:高原红细胞增多症患者及移居高原健康居民血浆组织因子水平明显升高。