遗传和环境因素对儿童青少年身体高度及其比例的影响

目前有关儿童青少年坐高、下肢长及其比值的报道多为非双生子人群的研究。为了解遗传和环境因素对儿童青少年坐高、下肢长及坐高与下肢长比值影响的相对大小,我们对796对6～18岁双生子的身高和坐高进行了测量,计算下肢长及坐高与下肢长比值,采用结构方程模型分析其遗传和环境相对效应。结果发现,校正年龄后,男女15～18岁年龄组坐高和下肢长的遗传度(0.63～0.78)均分别高于同性别低年龄段儿童青少年(0.31～0.68);坐高与下肢长比值的遗传度除9～11岁女生(0.84)外,其他年龄组均较低(男0.16～0.46,女0.21～0.57);共同环境因素和特殊环境因素对6～14岁儿童青少年各指标的作用较大。本研究提示,在快速发育时期,坐高、下肢长和坐高与下肢长比值对环境因素更为敏感,遗传度较低;机体越成熟,其遗传效应更强。     

Y染色体单倍型在中国汉族人群中的多态性分布与中国人群的起源及迁移

观察了由19个单核苷酸多态位点(SNP)组成的Y染色体单倍型在全国22个省市汉族人群中的分布. 结果表明, 中国南北人群的Y染色体单倍型组成有较大差异, 南方人群的多态性明显高于北方人群, 而后者中的单倍型仅包含前者的一部分, 其中单倍型H7, H10, H11和H12仅出现在南方群体. 这一观察结果与中国南北少数民族人群间差异相符, 提示现代人类自南方进入中国, 随后由南向北逐渐迁移. 同时对携带南北人群共同的单倍型个体在3个Y染色体微卫星标记位点进行了基因组分型, 据此估算了现代人类进入中国的时间大致在18 000～60 000 a前.     

鄂西青少年体质发育初步研究

目前,研究青少年体质发育的方法较多,作者试图用逐步回归分析法对此作些研究。 按照我国正常儿童青少年体格发育调查研究实施方案(儿童体格发育调查研究工作学习班,1976)和活体测量方法(黄新美,1983)的有关规定,对鄂西7—17岁的1533名青少年(男863人,女670人)进行了直接测量:1.身高;2.体重;3.上肢长;4.下肢长(由地面至大转子尖的距离)(靳仕信,1981);5.上半身长(身高—下肢长);6.上半身长与下肢长的比值。以上各项均值和标准差见表1.另外,还计算了下肢长指数（下肢长/身高×100）和上半身长指数（上半身长/身高×100）。将以上数据按性别、年龄逐个输入AppleII电子计算机（Basic语言）,对数据进行分析处理,用回归分析法（上海第二医学院数学教研室,1979;杨树勤,1985）分析青少年体重的变化与年龄、身高等七个因素的相关关系（见表2）,并对已进入方程式中的各项指标进行反复检查,最后,建立了推算青少年体重变化与年龄、身高的多元回归方程。     

现代中国人群形成与分化的形态证据——中国与非洲和欧洲人群头骨非测量特征分析

现代人群形成与分化导致生活在世界不同地区的人类形成了具有明显体质特征差别的人群(或种族)。对更新世末期及全新世以来不同地理区域近代和现代人群体质特征差别、相互亲缘关系的分析是现代人群形成与分化研究的重要组成部分。本文通过对21项头骨非测量特征在近代和现代中国人群, 以及现代非洲和欧洲人群共330例标本的出现率和表现特点的观察和数据分析, 发现绝大多数特征的出现率或表现特点在三个人群间都具有不同程度的差异, 有些特征在人群间的差异甚至非常明显。与非洲及欧洲人群相比, 现代中国人头骨总体显得纤细, 眉弓、角圆枕、颧三角、颧结节等反映头骨粗壮程度的特征在现代中国人群的发育明显弱于非洲和欧洲人群。此外, 现代中国人群还具有一些明显不同于非洲和欧洲人群的头骨非测量特征, 包括锐利的眶外下缘、相对平坦的眉间鼻根点、较圆隆的颅侧壁、平坦的顶孔人字区、深弧形的上颌颧突下缘, 梯形和左右不一的鼻额-额颌缝走向等。采用判别分析可以将67.0%—79.5%的标本正确地判别归入其原来所属的组群。其中对中国人群的正确判别率分别达到70.4%和82.9%。个体标本分布显示非洲人群表现较大的分散性, 而中国和欧洲人群样本的分布明显密集集中, 提示中国和欧洲人群似乎具有更多的衍生性特征。本研究还发现多数在人群间差别显著的头骨非测量特征与头骨粗壮程度有关, 作者对相关的问题进行了分析探讨。     

间断切口与长切口获取大隐静脉在冠状动脉旁路移植术中作用的对比研究

目的:比较冠状动脉旁路移植术(CABG)中采用间断切口与长切口获取大隐静脉作为静脉桥材料的优缺点。方法:选择2011年12月至2012年12月宁夏医科大学总医院心脏大血管外科111例行CABG的冠状动脉粥样硬化性心脏病患者为研究对象。根据术中获取大隐静脉方法的不同,随机将其分为两组,长切口组64例,在CABG中采用长切口法获取大隐静脉,间断切口组47例,在CABG中采用间断切口法获取大隐静脉。比较两组大隐静脉获取时间、下肢切口缝合时间、下肢手术时间、大隐静脉桥长度、下肢切口长度和下肢切口并发症发生率的差异。结果:间断切口组大隐静脉桥长度及下肢手术时间(45.4±6.7)cm,(65.8±10.3)min与长切口组(47.5±6.7)cm,(65.8±10.3)min比较无统计学差异(P0.05)。间断切口组获取大隐静脉的时间(48.9±8.3)min显著长于长切口组(37.3±5.8)min,下肢切口长度与缝合时间(17.0±3.5)cm,(16.9±3.4)min明显短于长切口组的(43.5±6.4)min,(31.7±5.9)min,差异均有统计学意义(P0.05)。两组大隐静脉壁的损伤情况比较无统计学差异(P0.05),但间断切口组术后下肢切口延迟愈合、感染、渗出、下肢血肿等并发症的发生率低于长切口组(P0.05)。结论:在冠状动脉旁路移植术中,间断切口获取大隐静脉能够显著缩短下肢手术切口长度,有助于减少术后下肢切口感染、延迟愈合、渗出、下肢血肿等并发症的发生。     

鲤鱼墩新石器时代居民头骨的形态学分析

本文对广东省湛江市遂溪县鲤鱼墩新石器时代遗址所出土的5例人类头骨进行了形态学分析。这些个体在种族特征方面较为一致, 应属于蒙古大人种的范畴, 可被视为"古华南类型"群体, 较接近于现代的南亚类型。岭南地区6组史前时期人群的聚类分析(马氏距离)和特征分析结果表明, 鲤鱼墩组、东湾仔北组、鱿鱼岗组与河宕组之间存在相对较近的形态学关系; 柳江人和甑皮岩组关系最为密切。在更为广泛的地理空间范围内, 对18组不同时期人群进行的聚类分析(马氏距离)和因子分析的结果显示, 鲤鱼墩人群与其他人群保持了相对较远的形态学距离。另外, 岭南地区的古人类从晚更新世阶段到新石器时代晚期, 在颅骨的绝对测量值上反映出一个短颅化、狭颅化和高颅化的过程, 而颅指数反映的却是长颅化的趋势, 说明该地区古人类的颅宽值较之颅长值减小得更快, 形成了颅骨尺寸在绝对值上的减小, 在颅指数上却反映出长颅化趋势的现象。由此可以推测, 现代南亚类型居民的典型长颅型特征可能是在全新世之初开始逐渐形成的。     

中国现代人群两性身高差异分布及其影响因素

本文对中国现代人群的两性身高差异分布状况及其影响因素进行了分析。选用152处中国现代人群（含69处汉族人群和83处少数民族人群）的男、女性身高数据,计算两性身高差异指数,并对比该指数在南、北方汉族和少数民族人群间的分布差异,同时分析纬度、气候、体格大小与城乡环境因素对两性身高差异程度的影响。结果表明,中国男性的平均身高比女性高出约7.16%(4.72%~9.26%）;南、北方汉族和少数民族之间的两性身高差异程度相似,北方汉族和南方汉族两性身高差异程度相似,但北方少数民族的两性身高差异明显大于南方少数民族。此外,两性身高差异程度与纬度、气温年较差和年均风速呈低度线性正相关,与年均气温、年均降水量和年均相对湿度呈低度线性负相关,而与体格大小和城乡环境并无显著关联。这提示遗传和自然环境因素在中国现代人群两性身高差异的区域化演变中更趋主导性,而社会环境因素的影响程度相对较低。     

古基因组解密末次盛冰期前后的东亚北部人群动态

现代人的起源与演化一直是地球与生命科学领域的研究焦点.过去10多年,围绕世界各地考古遗址人群开展的古基因组研究,在旧石器时代晚期以来欧洲、北亚等区域人群的演化问题上取得重大进展.然而,东亚人群古基因组研究则相对滞后,尤其是对中国人类古基因组的研究极度匮乏,使东亚人群遗传演化和迁徙融合的历史成为现代人演化进程里的重要"缺...     

2004—2008年落叶松人工林细根生产和死亡的季节动态

2004—2008年,采用微根管(minirhizotron)技术,对落叶松人工林细根生产和死亡进行连续动态观测,同时测定了温度(大气温度和土壤10 cm温度)和水分(降雨量和土壤10 cm深处含水量)的变化,研究细根生产、死亡的动态及其与温度和水分的关系.结果表明:落叶松细根年根长生产量在0.20～0.78 mm.cm-2,死亡量在0.26～0.72 mm.cm-2;2004—2006年细根年根长平均生产量(0.67 mm.cm-2)和死亡量(0.59 mm.cm-2)均高于2007—2008年细根年根长平均生产量和死亡量(0.37和0.39 mm.cm-2);在生长季内(5—10月),落叶松春末至夏季(6—7月)的细根生产量占全年产量的51%～68%,秋末(10月)仅占全年的1%～4%;而夏末(8月)和秋季(9—10月)细根死亡量占全年的59%～70%,早春(5月)占全年的1%～5%.相关分析表明,大气温度变化可以解释细根生产量66%的变异,而土壤10 cm深处温度解释24%,降雨量解释27%.细根的死亡量与土壤10 cm深处温度呈指数正相关.     

中国古代人群头骨的若干赤道人种特征检测

为探讨中国大陆古代人群与赤道人种人群之间的基因交流情况,本项研究对赤道人种的若干特征在中国古代人群头骨中的出现情况作检测。检测的材料包括3800~1200年前生活在新疆、青海、宁夏和河南安阳的12组人群的头骨以及现代华北和云南的人类头骨。结果表明:1)赤道人种若干特征能够在我国古代多个地区的人群中和现代华北和云南人群中检测到,表明中国大陆至少在3000~2000年前已存在赤道人种基因流入蒙古人种的人群之中的现象;2)赤道人种特征平均出现率在中国古代人群中很可能在地理上大致是由东向西递降,与当时这些人群中的欧亚人种特征平均出现率的地理上分布趋势呈相反方向,提示了在中国大陆至少在距今3000-2000年期间已经存在两个相反流向的外来"基因流"。     

中国人群的体部指数

本文通过对63452例18～97岁的中国人体部12项指数值的统计分析,得出目前该年龄段中国人的体部形态特征。研究发现,中国人总体体型为长躯干型、中肩型、中骨盆型、中腿型。男性为中胸型,女性为宽胸型。随着年龄增长,上半身会显得更短一些,上半身与下半身比例更小一些,胸部更显宽厚一些,躯干下部显得更宽一些,腿显得更长一些。与南方族群相比,蒙古语族群、突厥语族群身体更壮实一些,胸部更显得宽厚一些,上身更高一些,上肢显得短一些,躯干的上部(肩部)相对窄一些,躯干的下部(骨盆)相对更宽一些,上肢长和下肢长度比例更小一些。研究还发现,同等身高的男性和女性相比,男性的上肢长度、下肢长度一般都小于女性,而女性比男性有一个更大的坐高值。从躯干长度来比较,女性确实比男性腿短一些。下身长相等的中国男性、女性之间相比,女性的坐高大于男性。同等身高情况下,中国人的坐高比欧亚人种、非洲人种的坐高要大,即有较高的上半身高度。     

Brachial and crural indices of European late Upper Paleolithic and Mesolithic humans

Among recent humans brachial and crural indices are positively correlated with mean annual temperature, such that high indices are found in tropical groups. However, despite inhabiting glacial Europe, the Upper Paleolithic Europeans possessed high indices, prompting Trinkaus (1981) to argue for gene flow from warmer regions associated with modern human emergence in Europe. In contrast, Frayer et al. (1993) point out that Late Upper Paleolithic and Mesolithic Europeans should not exhibit tropically-adapted limb proportions, since, even assuming replacement, their ancestors had experienced cold stress in glacial Europe for at least 12 millennia. This study investigates three questions tied to the brachial and crural indices among Late Pleistocene and recent humans. First, which limb segments (either proximal or distal) are primarily responsible for variation in brachial and crural indices? Second, are these indices reflective of overall limb elongation? And finally, do the Late Upper Paleolithic and Mesolithic Europeans retain relatively and/or absolutely long limbs? Results indicate that in the lower limb, the distal limb segment contributes most of the variability to intralimb proportions, while in the upper limb the proximal and distal limb segments appear to be equally variable. Additionally, brachial and crural indices do not appear to be a good measure of overall limb length, and thus, while the Late Upper Paleolithic and Mesolithic humans have significantly higher (i.e., tropically-adapted) brachial and crural indices than do recent Europeans, they also have shorter (i.e., cold-adapted) limbs. The somewhat paradoxical retention of "tropical" indices in the context of more "cold-adapted" limb length is best explained as evidence for Replacement in the European Late Pleistocene, followed by gradual cold adaptation in glacial Europe.     

Trade-Offs in Relative Limb Length among Peruvian Children: Extending the Thrifty Phenotype Hypothesis to Limb Proportions

Background and Methods

Both the concept of ‘brain-sparing’ growth and associations between relative lower limb length, childhood environment and adult disease risk are well established. Furthermore, tibia length is suggested to be particularly plastic under conditions of environmental stress. The mechanisms responsible are uncertain, but three hypotheses may be relevant. The ‘thrifty phenotype’ assumes that some components of growth are selectively sacrificed to preserve more critical outcomes, like the brain. The ‘distal blood flow’ hypothesis assumes that blood nutrients decline with distance from the heart, and hence may affect limbs in relation to basic body geometry. Temperature adaptation predicts a gradient of decreased size along the limbs reflecting decreasing tissue temperature/blood flow. We examined these questions by comparing the size of body segments among Peruvian children born and raised in differentially stressful environments. In a cross-sectional sample of children aged 6 months to 14 years (n = 447) we measured head circumference, head-trunk height, total upper and lower limb lengths, and zeugopod (ulna and tibia) and autopod (hand and foot) lengths.

Results

Highland children (exposed to greater stress) had significantly shorter limbs and zeugopod and autopod elements than lowland children, while differences in head-trunk height were smaller. Zeugopod elements appeared most sensitive to environmental conditions, as they were relatively shorter among highland children than their respective autopod elements.

Discussion

The results suggest that functional traits (hand, foot, and head) may be partially protected at the expense of the tibia and ulna. The results do not fit the predictions of the distal blood flow and temperature adaptation models as explanations for relative limb segment growth under stress conditions. Rather, our data support the extension of the thrifty phenotype hypothesis to limb growth, and suggest that certain elements of limb growth may be sacrificed under tough conditions to buffer more functional traits.     

The effects of body proportions on thermoregulation: an experimental assessment of Allen's rule

Numerous studies have discussed the influence of thermoregulation on hominin body shape concluding, in accordance with Allen's rule, that the presence of relatively short limbs on both extant as well as extinct hominin populations offers an advantage for survival in cold climates by reducing the limb's surface area to volume ratio. Moreover, it has been suggested that shortening the distal limb segment compared to the proximal limb segment may play a larger role in thermoregulation due to a greater relative surface area of the shank. If longer limbs result in greater heat dissipation, we should see higher resting metabolic rates (RMR) in longer-limbed individuals when temperature conditions fall, since the resting rate will need to replace the lost heat. We collected resting oxygen consumption on volunteer human subjects to assess the correlation between RMR and lower limb length in human subjects, as well as to reexamine the prediction that shortening the distal segment would have a larger effect on heat loss and, thus, RMR than the shortening of the proximal segment. Total lower limb length exhibits a statistically significant relationship with resting metabolic rate (p<0.001; R(2)=0.794). While this supports the hypothesis that as limb length increases, resting metabolic rate increases, it also appears that thigh length, rather than the length of the shank, drives this relationship. The results of the present study confirm the widely-held expectation of Allen's rule, that short limbs reduce the metabolic cost of maintaining body temperature, while long limbs result in greater heat dissipation regardless of the effect of mass. The present results suggest that the shorter limbs of Neandertals, despite being energetically disadvantageous while walking, would indeed have been advantageous for thermoregulation.     

Body proportions in ancient Andeans from high and low altitudes

Living human populations from high altitudes in the Andes exhibit relatively short limbs compared with neighboring groups from lower elevations as adaptations to cold climates characteristic of high-altitude environments. This study compares relative limb lengths and proportions in pre-Contact human skeletons from different altitudes to test whether ecogeographic variation also existed in Andean prehistory. Maximum lengths of the humerus, radius, femur, and tibia, and femoral head breadth are measured in sex-specific groups of adult human skeletons (N = 346) from the central (n = 80) and the south-central (n = 123) Andean coasts, the Atacama Desert at 2,500 m (n = 102), and the southern Peruvian highlands at 2,000-3,800 m (n = 41). To test whether limb lengths vary with altitude, comparisons are made of intralimb proportions, limb lengths against body mass estimates derived from published equations, limb lengths against the geometric mean of all measurements, and principal component analysis. Intralimb proportions do not statistically differ between coastal groups and those from the Atacama Desert, whereas intralimb proportions are significantly shorter in the Peruvian highland sample. Overall body size and limb lengths relative to body size vary along an altitudinal gradient, with larger individuals from coastal environments and smaller individuals with relatively longer limbs for their size from higher elevations. Ecogeographic variation in relation to climate explains the variation in intralimb proportions, and dietary variation may explain the altitudinal cline in body size and limb lengths relative to body size. The potential effects of gene flow on variation in body proportions in Andean prehistory are also explored.     

Limb length and locomotor biomechanics in the genus Homo: an experimental study

The striking variation in limb proportions within the genus Homo during the Pleistocene has important implications for understanding biomechanics in the later evolution of human bipedalism, because longer limbs and limb segments may increase bending moments about bones and joints. This research tested the hypothesis that long lower limbs and tibiae bring about increases in A-P bending forces on the lower limb during the stance phase of human walking. High-speed 3-D video data, force plates, and motion analysis software were used to analyze the walking gait of 27 modern human subjects. Limb length, as well as absolute and relative tibia length, were tested for associations with a number of kinetic and kinematic variables. Results show that individuals with longer limbs do incur greater bending moments along the lower limb during the first half of stance phase. During the second half of stance, individuals moderate bending moments through a complex of compensatory mechanisms, including keeping the knee in a more extended position. Neither absolute nor relative tibia length had any effect on the kinetic or kinematic variables tested. If these patterns apply to fossil Homo, groups with relatively long limbs (e.g. H. ergaster or early H. sapiens) may have experienced elevated bending forces along the lower limb during walking compared to those with relatively shorter limbs (e.g. the Neandertals). These increased forces could have led to greater reinforcement of joints and diaphyses. These results must be considered when formulating explanations for variation in limb morphology among Pleistocene hominins.     

Limb bone bilateral asymmetry: variability and commonality among modern humans

Humans demonstrate species-wide bilateral asymmetry in long bone dimensions. Previous studies have documented greater right-biases in upper limb bone dimensions--especially in length and diaphyseal breadth--as well as more asymmetry in the upper limb when compared with the lower limb. Some studies have reported left-bias in lower limb bone dimensions, which, combined with the contralateral asymmetry in upper limbs, has been termed "crossed symmetry." The examination of sexual dimorphism and population variation in asymmetry has been limited. This study re-examines these topics in a large, geographically and temporally diverse sample of 780 Holocene adult humans. Fourteen bilateral measures were taken, including maximum lengths, articular and peri-articular breadths, and diaphyseal breadths of the femur, tibia, humerus, and radius. Dimensions were converted into percentage directional (%DA) and absolute (%AA) asymmetries. Results reveal that average diaphyseal breadths in both the upper and lower limbs have the greatest absolute and directional asymmetry among all populations, with lower asymmetry evident in maximum lengths or articular dimensions. Upper limb bones demonstrate a systematic right-bias in all dimensions, while lower limb elements have biases closer to zero %DA, but with slight left-bias in diaphyseal breadths and femoral length. Crossed symmetry exists within individuals between similar dimensions of the upper and lower limbs. Females have more asymmetric and right-biased upper limb maximum lengths, while males have greater humeral diaphyseal and head breadth %DAs. The lower limb demonstrates little sexual dimorphism in asymmetry. Industrial groups exhibit relatively less asymmetry than pre-industrial humans and less dimorphism in asymmetry. A mixture of influences from both genetic and behavioral factors is implicated as the source of these patterns.     

Anatomical Network Comparison of Human Upper and Lower,Newborn and Adult,and Normal and Abnormal Limbs,with Notes on Development,Pathology and Limb Serial Homology vs. Homoplasy

How do the various anatomical parts (modules) of the animal body evolve into very different integrated forms (integration) yet still function properly without decreasing the individual’s survival? This long-standing question remains unanswered for multiple reasons, including lack of consensus about conceptual definitions and approaches, as well as a reasonable bias toward the study of hard tissues over soft tissues. A major difficulty concerns the non-trivial technical hurdles of addressing this problem, specifically the lack of quantitative tools to quantify and compare variation across multiple disparate anatomical parts and tissue types. In this paper we apply for the first time a powerful new quantitative tool, Anatomical Network Analysis (AnNA), to examine and compare in detail the musculoskeletal modularity and integration of normal and abnormal human upper and lower limbs. In contrast to other morphological methods, the strength of AnNA is that it allows efficient and direct empirical comparisons among body parts with even vastly different architectures (e.g. upper and lower limbs) and diverse or complex tissue composition (e.g. bones, cartilages and muscles), by quantifying the spatial organization of these parts—their topological patterns relative to each other—using tools borrowed from network theory. Our results reveal similarities between the skeletal networks of the normal newborn/adult upper limb vs. lower limb, with exception to the shoulder vs. pelvis. However, when muscles are included, the overall musculoskeletal network organization of the upper limb is strikingly different from that of the lower limb, particularly that of the more proximal structures of each limb. Importantly, the obtained data provide further evidence to be added to the vast amount of paleontological, gross anatomical, developmental, molecular and embryological data recently obtained that contradicts the long-standing dogma that the upper and lower limbs are serial homologues. In addition, the AnNA of the limbs of a trisomy 18 human fetus strongly supports Pere Alberch''s ill-named "logic of monsters" hypothesis, and contradicts the commonly accepted idea that birth defects often lead to lower integration (i.e. more parcellation) of anatomical structures.     

Neural coupling between upper and lower limbs during recumbent stepping.

During gait rehabilitation, therapists or robotic devices often supply physical assistance to a patient's lower limbs to aid stepping. The expensive equipment and intensive manual labor required for these therapies limit their availability to patients. One alternative solution is to design devices where patients could use their upper limbs to provide physical assistance to their lower limbs (i.e., self-assistance). To explore potential neural effects of coupling upper and lower limbs, we investigated neuromuscular recruitment during self-driven and externally driven lower limb motion. Healthy subjects exercised on a recumbent stepper using different combinations of upper and lower limb exertions. The recumbent stepper mechanically coupled the upper and lower limbs, allowing users to drive the stepping motion with upper and/or lower limbs. We instructed subjects to step with 1) active upper and lower limbs at an easy resistance level (active arms and legs); 2) active upper limbs and relaxed lower limbs at easy, medium, and hard resistance levels (self-driven); and 3) relaxed upper and lower limbs while another person drove the stepping motion (externally driven). We recorded surface electromyography (EMG) from six lower limb muscles. Self-driven EMG amplitudes were always higher than externally driven EMG amplitudes (P < 0.05). As resistance and upper limb exertion increased, self-driven EMG amplitudes also increased. EMG bursts during self-driven and active arms and legs stepping occurred at similar times. These results indicate that active upper limb movement increases neuromuscular activation of the lower limbs during cyclic stepping motions. Neurologically impaired humans that actively engage their upper limbs during gait rehabilitation may increase neuromuscular activation and enhance activity-dependent plasticity.