人的体温调节

体温是指人体深部血液的平均温度而言,是相对恒定的,通常以直肠温度(约37.5℃)、口腔温度(约37.2℃)和腋窝温度(约36.8℃)来表示.其中直肠温度比较接近于深部体温,且较稳定,但测量不方便. 人体内各器官的温度,由于各器官代谢水平不同而略有差异.肝脏温度为38℃左右,在全身最高.大脑产热也较多,其温度接近38℃.肾脏、胰腺、十二指肠等要低些. 体表各部分皮肤温度的数值差别较大.在环境温度为23℃时测定,足的皮肤温度是27℃,手为30℃,躯干为32℃,头为33℃.由此可以看出四肢末梢皮肤温度低,越近躯干处的皮肤温度越高.身体左右两侧皮肤温度通常是相同的. 皮肤温度的高低与局部血流量有密切关系.凡能影响皮肤血管舒缩的因素(如环境温度变化或情绪紧张、激动等)都能对皮肤温度产生     

不同环境温度对有机磷杀虫剂毒死蜱引起大鼠体温变化的影响

目的: 观察不同环境温度对有机磷杀虫剂毒死蜱(CHP)引起大鼠体温变化的影响.方法: 用数字体温仪测量大鼠的结肠和尾部皮肤温度,观察25℃、16℃和32℃环境温度对口饲CHP引起结肠温度和尾部皮肤温度变化的影响.结果: 给置于25℃和16℃环境中的大鼠口饲CHP (20 mg·kg-1) 后,均可引起结肠温度明显的降低,尾部皮肤温度明显升高;但32℃环境中大鼠口饲CHP后却引起了明显的升温作用,而尾部皮肤温度无明显影响.结论: CHP对大鼠体温的影响与环境温度有关.     

不同功率递增速率对正常人心肺运动试验整体功能的影响Ⅰ—峰值运动相关指标及呼吸交换率的变化

目的:观察健康志愿者不同功率递增速率完成症状限制性极限心肺运动试验(CPET)对CPET峰值运动相关核心指标的影响,及运动中呼吸交换率(RER)的变化.以探讨不同功率递增速率对CPET峰值运动相关指标的影响.方法:选择12名健康志愿者在一周内不同工作天随机完成中等适度程度(30 W/min)及比较低(10 W/min)...     

荒漠沙蜥胚胎生长发育的温度适应性研究

为研究荒漠沙蜥胚胎发育的温度适应性,我们设定了3个温度(26℃、30℃、34℃)孵化荒漠沙蜥受精卵,并在胚胎孵化过程中对胚胎代谢和心率、新生幼体的形态学特征和幼体静止代谢率的温度适应性进行了研究。结果显示,随着卵的发育,荒漠沙蜥的胚胎代谢率和心率逐渐上升,在孵化后期达到最大;胚胎的心率对孵化温度具有较高的敏感性,随环境温度上升心率显著加快。孵化温度对荒漠沙蜥新生幼体的部分形态学指标有显著影响,26℃下孵化的荒漠沙蜥幼体体型较大。新生幼体的代谢率均比胚胎代谢率高,且不同温度下孵出的幼体其热适应性有较大差异,30℃组孵化出的新生幼体代谢水平最低。我们推测幼体在与孵化温度相同的环境下消耗较少的能量便可保证基本的生理活动需求;相反,个体需要消耗更多的能量才能适应从胚胎到幼体的不同生活史阶段的环境温度变化。     

根田鼠的活动代谢率

在15～30℃温度范围内, 运用踏车呼吸室以5 m/min, 10 m/min 和15 m/min 的运动速度, 对栖息于青海高原的根田鼠的代谢率、体温、蒸发失水进行了测定, 并计算了每个温度和运动速度时的热传导率。根田鼠的体温在任一速度时, 随环境温度的增加而增加, 当环境温度一定时, 体温随运动强度而升高, 代谢率随运动速度增加而增加。活动产热在低温条件下, 可能是对寒冷产热的替代, 而在比较缓和的温度时, 可能是对冷诱导产热的附加。温度一定时, 蒸发失水随运动速度增加而增加, 热传导也呈相似的变化趋势(15℃除外)。热传导在任一运动速度下, 随环境温度增加而增加。结果表明蒸发散热在高温或活动期间对根田鼠的体温调节有不可替代的作用。     

西伯利亚蝗气门结构及呼吸代谢对高温胁迫的响应

【目的】掌握西伯利亚蝗Gomphocerus sibiricus的气门结构和呼吸代谢应对高温胁迫的响应策略。【方法】运用扫描电镜观察西伯利亚蝗气门超显微结构,多通道昆虫呼吸仪测定18~42℃处理下西伯利亚蝗的O_2吸收率、CO_2释放率、代谢率和呼吸商。【结果】西伯利亚蝗共有10对气门,胸部2对,腹部8对,呈圆形或椭圆形,内侧着生有筛板,呈刺凸状,分布密集。18~42℃范围内,随温度升高,西伯利亚蝗呼吸代谢呈先上升后下降的趋势。18℃时西伯利亚蝗雌雄成虫的O_2吸收率、CO_2释放率和代谢率值显著小于其他温度下的相应值(P<0.05),雌虫分别为0.0022 m L/min、0.0019 m L/min和0.0210 m L/(g·min),雄虫分别为0.0016 m L/min、0.0016 m L/min和0.0236 m L/(g·min);21~27℃范围内,西伯利亚蝗雌雄成虫的呼吸代谢变化平稳,超过30℃呼吸代谢各指标值迅速上升,至36℃时雌雄成虫的O_2吸收率和代谢率值均显著大于其他温度下的相应值(P<0.05);雌虫分别为0.0071 m L/min和0.0592 m L/(g·min),雄虫分别为0.0089 m L/min和0.1108 m L/(g·min),39℃时CO_2释放率显著大于其他温度下的相应值(P<0.05),雌雄成虫分别为0.0074 m L/min和0.0067 m L/min。【结论】依据西伯利亚蝗呼吸代谢随温度变化特征可以判断,随气候持续变暖,西伯利亚蝗仍将是新疆高山、亚高山草原的重要致灾类群。     

温度对南方鲇肝组织离体线粒体代谢耗氧率的影响

于2007年2月,把40尾南方鲇1龄幼鱼分为5个不同的温度处理组,用流水式呼吸仪测定每尾实验鱼的静止代谢率(Ms:mg O2/h·kg),随即处死该实验鱼,提取其肝脏线粒体,采用氧电极在与其静止代谢测定相同的温度条件下以琥珀酸为代谢底物测定其线粒体的代谢耗氧率.在12.5、17.5、22.5、27.5和32.5℃条件下,静止代谢率的值分别为26.64、49.03、73.64、102.40、156.72mg O2/h·kg,单位线粒体蛋白重量的线粒体耗氧率(Mp)分别为12.24、11.76、16.28、21.56和31.43nmol O2/min·mg,单位组织重量的线粒体耗氧率(Mt)则分别为64.02、78.72、117.51、121.57和194.20nmol O2/min·g.为了比较南方鲇肝脏离体线粒体的底物偏好性,在27.5℃条件下还测定了其以丙酮酸 苹果酸为底物时的耗氧率.结果显示:该种鱼肝脏离体线粒体对琥珀酸的氧化代谢能力显著高于丙酮酸 苹果酸(p<0.05);在实验温度范围内,鱼体的Ms、Mp和Mt值分别与温度(T: ℃)之间呈显著的双对数直线相关,协方差分析表明,鱼体静止代谢率与线粒体代谢率回归方程的斜率(温度指数b)差异显著(p<0.05),即鱼体静止代谢率与线粒体代谢率随温度变化的趋势不一致.经过计算发现:在最低实验温度条件下(12.5℃)肝器官线粒体代谢总耗氧率占鱼体静止代谢总耗氧率的比例显著高于其他温度梯度(p<0.05).通过讨论认为:在低温条件下,肝脏线粒体代谢水平随温度下降速率的减小是该种鱼抵抗低温的适应性调节机制.     

太湖绿翅鸭、琵嘴鸭、斑嘴鸭气体代谢的季节变化

本文在秋、冬、春三季测定了江苏太湖越冬的绿翅鸭(Anas crecca)、琵嘴鸭(Anas clypeata)和斑嘴鸭(Anas poecilorhycha)的静止代谢率(RMR)。分析了RMR与环境温度以及与体重之间的关系。结果表明,3种野鸭的静止代谢率有明显的季节变化。根据实验数据得出了3个季节的RMR与环境温度以及体重的回归方程。利用方程式可用已知的温度和体重推算出野鸭的静止代谢率。RMR可作为估测野鸭周年或季节性的能量收支的参数。     

不同温度下黑线仓鼠应对食物短缺的能量学对策

食物资源的不确定性是动物在自然环境中面临的重要挑战之一."代谢率转换"假说认为,动物应对食物短缺的能量学策略在于降低代谢率以减少能量支出.然而在不同环境温度下非冬眠小型哺乳动物应对食物短缺的"代谢率转换"策略,尚不明确.为探究这一问题,将成年雄性黑线仓鼠在低温(5.0℃)、室温(21.0℃)和高温(32.5℃)下断食处...     

不同功率递增速率对正常人心肺运动试验整体功能的影响Ⅰ—峰值运动相关指标及呼吸交换率的变化

目的: 观察健康志愿者不同功率递增速率完成症状限制性极限心肺运动试验（CPET）对CPET峰值运动相关核心指标的影响,及运动中呼吸交换率（RER）的变化。以探讨不同功率递增速率对CPET峰值运动相关指标的影响。方法: 选择12名健康志愿者在一周内不同工作天随机完成中等适度程度（30 W/min)及比较低（10 W/min）和比较高（60 W/min）3种不同功率递增速率CPET。按标准方法比较CPET数据主要峰值运动核心指标：峰值运动时的摄氧量、二氧化碳排出量、负荷功率、呼吸频率、潮气量、分钟通气量、心率、血压和氧脉搏,运动持续时间和CPET各时段的RER。对三组不同功率递增速率下各个指标的差异进行组间两两比较。结果: 与中等适度功率递增速率组比较,比较低和比较高功率递增速率组的峰值功率分别显著地降低和升高（（162.04±41.59）W/min vs （132.92±34.55） W/min vs （197.42±46.14） W/min, P<0.01）;运动时间显著延长和缩短（（5.69±1.33） min vs （13.49±3.43） min vs （3.56±0.76） min,P<0.01）;峰值RER（1.27±0.07 vs 1.18±0.06 vs 1.33±0.08,P<0.01~P<0.05）与恢复期RER最大值（1.72±0.16 vs 1.61±0.11 vs 1.81±0.14,P<0.01~P<0.05）均显著降低和升高。结论: 不同功率递增速率CPET显著改变峰值运动时的功率、运动持续时间、峰值RER和恢复期最大RER。CPET规范化操作要选择个体化适合受试者的中等适度功率递增速率,而且也不能以某一固定的RER值作为保证安全、受试者达到极限运动和提前终止运动的依据。     

Papillomaviruses: different genes have different histories

Papillomaviruses (PVs) infect stratified squamous epithelia in vertebrates. Some PVs are associated with different types of cancer and with certain benign lesions. It has been assumed that PVs coevolved with their hosts. However, recently it has been shown that different regions of the genome have different evolutionary histories. The PV genome has a modular nature and appeared after the addition of pre-existent blocks. This order of appearance in the PV genome is evident today in the different evolutionary rates of the different genes, with new genes--E5, E6 and E7--diverging faster than old genes--E1, E2, L2 and L1. Here, we propose an evolutionary framework aiming to integrate genome evolution, PV biology and epidemiology of PV infections.     

Gene therapy: different strategies for different applications

American Society of Gene Therapy: First Annual MeetingSeattle, Washington, USA, 28–31 May 1998     

Ras proteins: different signals from different locations

Ras signalling has classically been thought to occur exclusively at the inner surface of a relatively uniform plasma membrane. Recent studies have shown that Ras proteins interact dynamically with specific microdomains of the plasma membrane as well as with other internal cell membranes. These different membrane microenvironments modulate Ras signal output and highlight the complex interplay between Ras location and function.     

Paramyxoviruses: different receptors - different mechanisms of fusion

Paramyxovirus-mediated membrane fusion usually requires an interaction between the viral-attachment and -fusion proteins. The mechanism by which this interaction regulates fusion differs between paramyxoviruses that bind to sialic acid-containing receptors and those that recognize specific proteins. The recently solved structure of the globular head of the measles virus hemagglutinin suggests that this difference might be related to the location of the receptor-binding sites on the attachment proteins of the two classes of paramyxoviruses.     

Three different human tumor cell lines contain different oncogenes

We have obtained foci of transformed mouse cells after transfection of human DNA from colon and bladder carcinoma cell lines and a promyelocytic leukemia cell line. These foci can be shown to contain a large number of human DNA sequences by use of highly repetitive human DNA sequence probes. Cell DNA from primary foci can be used in a subsequent cycle of transfection resulting in secondary foci that contain relatively little human DNA. Secondary foci appear to contain only the human sequences proximal to those responsible for the transformed phenotype. A set of characteristic DNA restriction fragments is found in common among secondary foci derived from each tumor cell line DNA. Comparison of the common DNA fragments found in secondary foci derived from three different human tumor cell lines indicates that these three cell lines contain three different transforming genes.     

FlgM proteins from different bacteria exhibit different structural characteristics

Intrinsically disordered proteins (IDPs) are a unique class of proteins that do not require a stable structure for function. The importance of IDPs in many biological processes has been established but there remain unanswered questions about their evolution and conservation of their disordered state within a protein family. Our group has been studying the structural similarities among orthologous FlgM proteins, a model class of IDPs. We have previously shown that the FlgM protein from the thermophile Aquifex aeolicus has more structure at A. aeolicus' physiological temperature (85 °C) than is observed for the Salmonella typhimurium FlgM, suggesting that the disordered nature of FlgM varies among organisms and is not universally conserved. In this work, we extend these studies to the FlgM proteins from Escherichia coli, Pseudomonas aeruginosa, Proteus mirabilis, and Bacillus subtilis. We demonstrate that the B. subtilis, E. coli, and S. typhimurium FlgMs exist in a premolten globule-like conformation, though the B. subtilis FlgM is in a more compacted conformation than the other two. The P. aeruginosa and P. mirabilis FlgM proteins exist in a currently unknown conformation that is not either coil-like or premolten globule-like. The P. aeruginosa FlgM appears to contain more weak intramolecular contacts given its more compacted state than the P. mirabilis FlgM. These results provide experimental evidence that members of the same protein family can exhibit different degrees of disorder, though understanding how different disordered states evolve in the same protein family will require more study.     

Two rheologically different gastric mucus secretions with different putative functions

Previous work has shown the presence of different mucin gene products and glycosylated species in gastric mucus secretions, however, the functional relevance of these differences is unclear. This study aimed to investigate rheologically, differences in the gel behaviour within gastric mucus samples using a pig model. Rheological measurements were made on a Bohlin CVO50 rheometer. Mucins were characterised by antigenicity, lectin reactivity and proteolytic fragmentation patterns. Two distinct mucus gel secretions, one compliant with and the other resistant to shear stress, were removed from the gastric mucosa. The two gels had different rheological behaviour profiles and exhibited structural differences in their constituent mucins. The shear-compliant mucus was located superficially to the adherent shear-resistant mucus layer and was shown not to be a proteolytic product of the latter. This study has demonstrated that there are two rheologically distinct mucus gel secretions with structural/compositional differences in the stomach. Rheological properties suggest that the adherent, shear-resistant gel could provide the mucus barrier in vivo while the shear-compliant gel could act primarily as a lubricant.