运动对大鼠血小板L—精氨酸转运的影响

本工作在游泳大鼠模型上,观察血小板Ｌ－精氨酸（Ｌ－Ａｒｇ）转运特征,并观察凝血酶和ＰＡＦ对血小板Ｌ－Ａｒｇ转运的影响。结果发现,运动大鼠血小板Ｌ－Ａｒｇ转运明显高于未运动对照大鼠,表现在高亲和性最大转运速率（Ｖｍａｘ）明显增高（５０．５６±３．２７ｐｍｏｌ／１０８ｖｓ４５．８４±２．３６ｐｍｏｌ／１０８血小板／ｍｉｎ。Ｐ＜０．０５）,米氏常数亦显著增加（２．１４±０．２３μｍｏｌ／Ｌｖｓ１．４６±０．１３μｍｏｌ／Ｌ,Ｐ＜０．０１）。应用刺激剂凝血酶和ＰＡＦ诱导运动大鼠血小板Ｌ－Ａｒｇ转运速率增加的幅度明显高于未运动对照大鼠（Ｐ＜０．０１）。实验结果表明,运动能增强血小板转运Ｌ－Ａｒｇ的效率。提示,运动可能促进血小板一氧化氮（ＮＯ）生成,抑制血小板聚集,防治血管栓塞性疾病     

踏车运动试验对高血压病合并冠心病的诊断意义

本文回顾了４７例无心肌缺血症状和平静心电图无ＳＴ段改变的原发笥高血压病患者的车运动试验结果。阴性率３２％,阳性患者中７４．５％为下斜型ＳＴ段降低,持续时间２－１２ｍｉｎ。提示踏车运动试验对原发性高血压病患者筛选有否合并冠心病,具有较高的辅助诊断价值。     

肾多巴胺受体对血量扩张和脑室高张盐溶液注射引起促钠排泄的作用

本工作观察麻醉兔用氟哌啶醇阻断肾多巴胺受体对血量扩张（ＶＥ）和脑室高张盐溶液注射（ＩＣＨＮａ）引起促钠排泄反应的影响。在ＶＥ实验中。对照组与氟哌啶醇组排销量增加峰值分别为６５．６±１５．０与１９．０±５．５μｍｏｌ／ｍｉｎ（Ｐ＜０．０２）;在ＩＣＨＮａ实验中,对照组与氟哌啶醇组排钠量增加峰值分别为２８．９±４．６与２９．０±５．８μｍｏｌ／ｍｉｎ（Ｐ＞０．０５）,在肾多巴胺受体完好兔实验中,ＶＥ＋ＩＣＨＮａｇ;起的促钠排泄大于ＶＥ（Ｐ＜０．０１）或ＩＣＨＮａ（Ｐ＜０．０１）引起的反应。肾多巴胺受体阻断也可显著减弱ＶＥ＋ＩＣＨＮａ引起促钠排泄反应。结果表明：肾多巴胺受体阻断显著减弱ＶＥ以及ＶＥ＋ＩＣＨＮａ引起促钠排泄,对ＩＣＨＮａ的反应无效;在正常兔ＶＥ＋ＩＣＨＮａ引起促钠排泄显著大于各单一刺激的反应。     

青年男性高原移居者最大摄氧量计算公式的推导

最大摄氧量（Ｖｏ２ｍａｘ）是评价人体体力的重要指标,其测定方法分直接法和间接法两种。目前所推导的间接计算公式都是在平原、或是在进入高原初期推导的,不适用于高原习服人群。本研究采用逐步回归的方法,推导出移居高原７－２７个月、不同高度的青年男性Ｖｏ２ｍａｘ间接计算公式。在海拔３６８０ｍ地区,Ｖｏ２ｍａｘ（Ｌ／ｍｉｎ）＝１．１５３１＋０．００７３２７身高（ｃｍ）＋０．０１６１３体重（ｋｇ）－０．００５８８３晨脉（ｂ／ｍｉｎ）－０．００４５３４运动心率（６０Ｗ,６／ｍｉｎ）,Ｒ＝０．７４５,Ｐ＜０．０１,ＳＳ＝３．７７９９;或Ｖｏ２ｍａｘ（Ｌ／ｍｉｎ）＝１．２１８６＋０．０１９８４体重（ｋｇ）＋０．０７２５９肺活量（Ｌ）－０．００６６５９晨脉（ｂ／ｍｉｎ）,Ｒ＝０．７１３,ｐ＜０．０１,ｓｓ＝３．９６３６。在４３５０ｍ地区,Ｖｏ２．ｍａｘ（Ｌ／ｍｉｎ）＝０．４９１７＋０．０１６８７体重（ｋｇ）＋０．１１０９肺活量（Ｌ）＋０．００１９８３屏气时间（Ｓ）,Ｒ＝０．７８１,Ｐ＜０．０１,ＳＳ＝２．１３５６。计算值与实测值比较,变异系数在１３％以内,结果准确可靠,适用于青年男性高原习服移居者。     

红景天中药复方对低氧劳动能力的影响

我们研制了以藏产大花红景天为主要成分的中药复方用以提高机体的低氧劳动能力。在模拟海拔１００００ｍ的小鼠游泳实验中,药物组和对照组动物的存活时间分别为７３．２±３．８和６０．５±４．０ｍｍ（Ｐ＜０．０５）;游泳６０ｍｉｎ（相当于对照组的平均存活时间）以后死亡的百分数分别为５３．０％和３５．８％（Ｐ＜０．０５）。大鼠在模拟海拔５０００ｍ游泳１ｈ,药物组和对照组动物的血乳酸含量分别为１４．６±１．８和２１．１±１．９ｍｍｏｌ／Ｌ（Ｐ＜０．０５）。在模拟海拔４３００ｍ低压舱内人体运动负荷试验中,药物组和对照组受试者的ＰＷＣ１７０分别为９８０．４±５２．８和８６６．４±３０．０（Ｐ＜０．０１）。提示,红景天中药复方能明显提高低氧劳动能力。     

慢性低氧下普通大鼠与低氧敏感大鼠的血液气体变化

普通大鼠（ＳＤ）与低氧敏感大鼠（ＨＳ）经减压舱内模拟海拔５０００ｍ高度下３周低氧,观察到ＳＤ与ＨＳ的Ｈｂ有显著差异,前者高于后者（分别为２７．３±０．６;２４．５±０．８ｇ％Ｐ＜０．０１）。此时ＳＤ血液中的ＰＣＯ２已恢复正常,而ＨＳ血液中的ＰＣＯ２却比ＳＤ血液中的ＰＣＯ２低（分别为４．３±０．１;５．６±０．３ｋＰａＰ＜０．０１）。在慢性低氧初期,ＨＳ的ｐＨ值比ＳＤ明显降低（分别为７．１８±０．０３;７．２９±０．０２,Ｐ＜０．０５）。但随着低氧时间延长ＨＳ的ｐＨ值很快上升并超过ＳＤ（分别为７．２５±０．０２;７．１７±０．０３Ｐ＜０．０５）。两者的血液氧没有明显差异。实验结果提示普通大鼠与低氧敏感大鼠对慢性低氧反应有不同的生理机制。     

心肺压力感受器持续卸荷对前臂血流、血管阻力及心率变异性谱的影响

低压值下体负压（ＬＢＮＰ）可仅使心肺压力感受器卸荷。采用－２ｋＰａＬＢＮＰ实验结果表明：ＬＢＮＰ既不引起动脉血压变化,也不引起心率改变,但却引起基础胸阻抗（Ｚ。）从对照的２１．８±０．４升高到２２．５±０．５Ω（Ｐ＜０．０１）,前臂血管阻力（ＦＶＲ）从１２．３±０．９升高到１９．９±１．４Ｕ（Ｐ＜０．０１）,前臂血流（ＦＢＦ）从对照时７．１±０．５降低到４．３±０．３ｍｌ·ｍｉｎ￣（－１）·１００ｍｌ￣（－１）,心率变异性谱（ＨＲＶ）未发生任何变化,即心肺压力感受器卸荷时心脏自主神经活动水平与均衡性不受影响。由于ＦＶＲ和ＦＢＦ的变化可间接反映外周血管交感传出活动水平,上述实验结果提示,心肺压力感受器对外周血管及心脏自主神经活动的调节可能存在机能分化现象。     

丹皮酚对心肌细胞自律性和延迟后除极的影响

目的与方法：采用常规玻璃微电极技术研究丹皮酚对离体心肌细胞自律性（ＡＭ）、延迟后除极（ＤＡＤ） 及触发活动（ＴＡ）的影响。结果：１．８×１０－４ｍｏｌ／Ｌ丹皮酚灌流组,肾上腺素（Ａｄｒ）的阈浓度空白对照组为（１．２８±０．５７）μｍｏｌ／Ｌ,药后为（１．５６±０．５３）μｍｏｌ／Ｌ（ｎ＝９,Ｐ＞０．０５）;用（１．８×１０－ ３） ｍｏｌ／Ｌ丹皮酚（Ｐａｅ）灌流组,Ａｄｒ 浓度由空白对照组的（１．２２ ±０．６２）μｍｏｌ／Ｌ升高到（６．２２±２．１１）μｍｏｌ／Ｌ（ｎ＝９,Ｐ＜０．０１）。１．８×１０－３ｍｏｌ／Ｌ的Ｐａｅ 能明显抑制哇巴因（Ｏｕａ）诱发的ＤＡＤ的幅值,当基本刺激周长为５００,４００,３００ 和２００ ｍｓ 时,其ＤＡＤ幅值从（５．５±２．０）ｍＶ,（７．３±２．１）ｍＶ,（８．０ ±２．４）ｍＶ和（９．２±１．９）ｍＶ减小到（３．０±１．１）ｍＶ、（３．６±１．７）ｍＶ,（４．３±２．０） ｍＶ和（５．９ ±１．６） ｍＶ,Ｐ＜０．０１。当基本刺激周长为２００ ｍｓ时,ＴＡ 数目由５．５±１．０ 降至０．７±０．３（Ｐ＜０．０１）。结论：丹皮酚能抑制心肌细胞ＡＭ、ＤＡＤ及ＴＡ,具有抗心律失常作用     

血管紧张素Ⅱ对大鼠心肌肌浆网Ca~(2+),Mg~(2+)-ATPase基因转录调节的影响

观察血管紧张素Ⅱ（ＡｎｇⅡ）对心肌肌浆网Ｃａ２＋,Ｍｇ２＋－ＡＴＰａｓｅ基因（ＳＥＲＣＡ２ａ）转录调节的影响,评价ＤＭＰ８１１对此效应的干预作用．６周龄雄性ＳＤ大鼠随机分为３组,每组６只．组１：生理盐水输注;组２：ＡｎｇⅡ输注＋ＤＭＰ８１１管饲（３ｍｇ·ｄ－１·ｋｇ－１）;组３：ＡｎｇⅡ输注（２００ｎｇ·ｍｉｎ－１·ｋｇ－１．１周后称其体重,取心脏并称重,提取心脏总ＲＮＡ后采用Ｎｏｒｔｈｅｒｎｂｌｏｔ的方法检测ＳＥＲ－ＣＡ２ａ的转录水平,采用ＲＴ－ＰＣＲ检测ＡｎｇⅡ１型受体（ＡＴ１）ｍＲＮＡ水平．实验后,组３心重（ＣＷ）、心重／体重（Ｃ／Ｂ）、ＡＴ１受体转录水平均高于组１（分别增加４．７±０．４％,４．９±０．９％和２４．７±３．５％;Ｐ＜０．０１）,而ＳＥＲＣＡ２ａ基因转录水平显著低于组１（降低２０．１±３．０％,Ｐ＜０．０１）,并且ＳＥＲＣＡ２ａｍＲＮＡ水平与ＡＴ１受体ｍＲＮＡ水平呈负相关（ｒ＝－０．７４,Ｐ＜０．０１）．ＡｎｇⅡ导致的上述改变能被ＤＭＰ８１１完全阻断．ＡｎｇⅡ通过其Ⅰ型受体的介导,诱导了ＳＥＲＣＡ２ａ的转录下调     

热性发热兔血浆脂多糖（LPS）浓度与生理反应的变化

在干球温度４２℃、湿球温度３５℃、相对湿度６０％条件下,测定了２４只热暴露兔［分为肛温维持４３℃（Ⅰ）组和肛温持续上升（Ⅱ）组］的心率、平均动脉压、呼吸频率、肛温及血浆ＬＰＳ浓度等指标。结果显示：（１）Ⅰ、Ⅱ组当Ｔｒ升达４３℃,热暴露时间分别为１００ｍｉｎ、６０ｍｉｎ时,血浆ＬＰＳ浓度分别为０．１９５ｎｇ／ｍｌ、０．１８０ｎｇ／ｍｌ,与实验前比,Ｐ＜０．０５。两组临死前,热暴露时间分别为２２０ｍｉｎ、１２０ｍｉｎ（Ⅱ组Ｔｒ４４．１５℃）时,其血浆ＬＰＳ浓度分别为０．２８５ｎｇ／ｍｌ、０．２４９ｎｇ／ｍｌ,Ｐ＜０．０１;（２）Ｔｒ４３℃和临死前两阶段ＬＰＳ的上升速率,Ⅰ组分别为０．０００６６ｎｇ／ｍｉｎ和０．０００６７ｎｇ／ｍｉｎ,Ⅱ组分别为０．０００８３ｎｇ／ｍｉｎ和０．００１１３ｎｇ／ｍｉｎ;（３）动物受热过程,Ｔｒ升至４３℃时,ＨＲ和ＭＡＰ达峰值水平,而呼吸频率则开始下降。本文结果提示,ＬＰＳ在中暑的病理生理学过程中可能是一个值得重视的因素     

Neuromuscular fatigue during prolonged pedalling exercise at different pedalling rates

The purpose of this study was to estimate the differences in neuromuscular fatigue among prolonged pedalling exercises performed at different pedalling rates at a given exercise intensity. The integrated electromyogram (iEMG) slope defined by the changes in iEMG as a function of time during exercise was adopted as the measurement for estimating neuromuscular fatigue. The results of this experiment showed that the relationship between pedalling rate and the means of the iEMG slopes for eight subjects was a quadratic curve and the mean value at 70 rpm [1.56 (SD 0.65) V·min^–1] was significantly smaller (P < 0.01) than that at 50 and 60 rpm [2.25 (SD 0.54), and 2.22 (SD 0.68), respectively]. On the other hand, the mean value of oxygen consumption obtained simultaneously showed a tendency to increase linearly with the increase in pedalling rate, and the values at 70 and 80 rpm were significantly higher than those at 40 and 50 rpm. In conclusion, it was demonstrated that the degree of neuromuscular fatigue estimated by the iEMG changes for five periods of prolonged pedalling exercise at a given exercise intensity was different among the different pedalling rates, and that the pedalling rate at which minimal neuromuscular fatigue was obtained was not coincident with the rate at which the minimal oxygen consumption was obtained, but was coincident with the rate which most subjects preferred. These findings would suggest that the reason why most people prefer a relative higher pedalling rate, even though higher oxygen consumption is required, is closely related to the development of neuromuscular fatigue in the working muscles.     

On-station comparative analysis of reproductive and survival performance between Red Maasai,Dorper, and Merino sheep breeds

The reproductive performance of ewes and the survivability of lambs to weaning have a critical economic impact on sheep farming worldwide. Further, knowledge of major mortality causes allows an opportunity for improved flock management to evade financial losses. The maximum likelihood estimates for generalised linear mixed models and chi-square test methods were used to examine 971 mating records, 839 and 763 lambs born and weaned (singles or twins) from the Naivasha Sheep and Goats station in Kenya for the years 2011 to 2020 consisting of Dorper, Red Maasai (RedM), and Merino breeds. The RedM (P < 0.05) outperformed Dorper and Merino in weaning rate, whereas reproductive performance between the three breeds was not significantly different (P > 0.05) in litter size and multiple lambings per ewe lambing. On the one hand, Dorper significantly (P < 0.05) outperformed the other two breeds only in weaning weight per lamb born. In addition, among all the major causes of death, pneumonia appeared to be the one to which Dorper breeds were most susceptible (chi-square test, P < 0.05). According to the findings of this study, neither the Dorper nor the Merino sheep breeds were reproductively superior to the RedM in an extensive semi-arid production environment. In addition, Dorper's susceptibility to the leading causes of mortality, particularly pneumonia and sheep pox, were relatively high compared to other breeds and could be a precursor to massive economic losses for Dorper sheep producers. In contrast to the indigenous RedM breed, imported sheep breeds appeared to be more susceptible to major mortality-related under an extensive production system. Therefore, regardless of weaning weight, RedM breed production appears to be a more viable investment for small-scale farmers, particularly in semi-arid regions.     

Predation rate and numerical response of Aphidoletes aphidimyza feeding on different densities of Aphis craccivora

Predation rate and numerical response are basic to any investigation of predator–prey relationships and key components in the selection of predators for biological control. The density-dependent predation rate and numerical response of Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae) to varying densities (5, 10, 20, 40, 60 and 80) of third-instar Aphis craccivora (Koch) (Hemiptera: Aphididae), were studied in laboratory conditions [23±1°C, 70 ± 5% relative humidity (RH), and a photoperiod of 16:8 h L:D. Predation rate data were analysed using the age-stage, two-sex consumption rate software. Net consumption rate (C₀) increased by increasing prey density. The lowest and highest net consumption rates were 20.75 and 190.8 prey nymphs at densities of 5 and 80 A. craccivora. The transformation rate from prey population to predator offspring (Q_p) increased by increasing prey density. The reproductive numerical response, in terms of eggs laid, increased curvilinearly with increasing prey density. Females laid 121.375 ± 4.301 eggs when exposed to the highest prey density (80) and 52.5 ± 1.544 eggs at lowest prey density (5). It can be concluded that different densities of A. craccivora influenced the reproductive performance of A. aphidimyza in terms of predation rate and numerical response.     

Time dependency of molecular rate estimates and systematic overestimation of recent divergence times

Studies of molecular evolutionary rates have yielded a wide range of rate estimates for various genes and taxa. Recent studies based on population-level and pedigree data have produced remarkably high estimates of mutation rate, which strongly contrast with substitution rates inferred in phylogenetic (species-level) studies. Using Bayesian analysis with a relaxed-clock model, we estimated rates for three groups of mitochondrial data: avian protein-coding genes, primate protein-coding genes, and primate d-loop sequences. In all three cases, we found a measurable transition between the high, short-term (< 1-2 Myr) mutation rate and the low, long-term substitution rate. The relationship between the age of the calibration and the rate of change can be described by a vertically translated exponential decay curve, which may be used for correcting molecular date estimates. The phylogenetic substitution rates in mitochondria are approximately 0.5% per million years for avian protein-coding sequences and 1.5% per million years for primate protein-coding and d-loop sequences. Further analyses showed that purifying selection offers the most convincing explanation for the observed relationship between the estimated rate and the depth of the calibration. We rule out the possibility that it is a spurious result arising from sequence errors, and find it unlikely that the apparent decline in rates over time is caused by mutational saturation. Using a rate curve estimated from the d-loop data, several dates for last common ancestors were calculated: modern humans and Neandertals (354 ka; 222-705 ka), Neandertals (108 ka; 70-156 ka), and modern humans (76 ka; 47-110 ka). If the rate curve for a particular taxonomic group can be accurately estimated, it can be a useful tool for correcting divergence date estimates by taking the rate decay into account. Our results show that it is invalid to extrapolate molecular rates of change across different evolutionary timescales, which has important consequences for studies of populations, domestication, conservation genetics, and human evolution.     

Optimising a clearance index based on neutral red as an indicator of physiological stress for bivalves

Neutral red is a weakly cationic dye that is soluble in water, has a low toxicity for almost all classes of organisms, and has been used as a histological and vital stain since the early twentieth century. Estimating the volume of water cleared of indicator material by suspension feeding bivalves (clearance or filtration rate) was one of the earliest applications of neutral red; however, less than thirty studies have applied this methodology since it was first described in 1954. The feeding/clearance rate is used as a sensitive indicator of physiological stress and is therefore an early-warning tool that is suitable for monitoring the ecological status of water bodies. The aim of our study was to optimise a clearance index based on neutral red solution by addressing the effect of i) the acidifying pH; ii) the holding temperature before spectrophotometric reading; and the time iii) before and iv) after the acidification of solutions of neutral red used to carry out clearance assays. Furthermore, as a case study we fine-tuned the clearance assay for the edible estuarine bivalve, Cerastoderma edule. The results showed that there were no statistical differences as regards the absorbance of neutral red solutions holding at 4 or 20 °C or a solution acidified between the ranges of pH 4–5. However, the absorbance significantly decreased as the pH increased to pH 6. The time before acidification had no significant effect on absorbance. Once the neutral red solution is acidified, the absorbance decreases over time, signifying that the absorbance should be read in the first 24 h. The concentration of neutral red used in the experiences should be sufficient to allow final concentrations of over 0.5 mg/L after the clearance period, since we observed that the sensitivity of this protocol decreased at low concentrations. In the case of C. edule, the optimum clearance conditions per individual were found to be 100 ml of 4 mg/L of neutral red dye during a 30 min period in dark conditions. A bioassay using a clearance index of C. edule based on this simple colorimetric technique would appear to be a potential tool for implementation in environmental monitoring programmes for water quality assessment in accordance with European directives. We trust that the new harmonised protocol will become a widely used and cost-effective means to monitor the clearance index as an indicator of physiological stress for bivalves.     

Photorespiration Rate in Spinach Leaves Under Moderate NaCl Stress

We analyzed the effect of NaCl stress on photorespiration of spinach leaves by calculating the rate of carboxylation/oxygenation of ribulose-1,5-bisphosphate carboxylase/oxygenase, and by measuring the content of amino acids produced through photorespiration. After 20 d of NaCl stress the carboxylation rate was reduced while the oxygenation rate was not affected. The contents of serine, glycine, and alanine increased relevantly. The amount of glutamine also increased after 20 d but the amount of glutamate did not. Hence photorespiration may be stimulated under moderate NaCl stress. A relevant electron transport rate was observed under CO₂-free air, which may indicate refixation of photorespiratory CO₂. When NaCl accumulation proceeded for more than 20 d, photosynthesis was reduced and the content of photo-respiratory amino acids started to decrease, but the oxygenation rate did not change. This revised version was published online in September 2006 with corrections to the Cover Date.     

广西地区脑血管病城乡抽样对比分析

本文着重分析了广西城市和农村脑血管病发病情况的差异。我们发现城市CVD发病率、患病率明显高于农村,但是农村CVD的死亡率高于城市,其中我们对其原因作了初步的探讨。     

Ingestion Rates of Some Daphnia Species in a Shallow Lake (Lake Balaton,Hungary)

Filtering rates of three species of Daphnia were studied in situ by the ¹⁴C technique during the summer in a lake with a water temperature of 20-25°C (Lake Balaton, Hungary). The renewal time of gut contents proved to be 3-5 min in each of the three species whether fed on natural or artificial food. From May to September, filtering rates of D. cucullata, D. hyalina and D. galeata averaged 7.8, 10.3 and 9.2 ml ind.⁻¹ day⁻¹, respectively. Identically long individuals of all three species had almost the same filtering rates in spring, whereas in summer animals of identical weights had similar filtering rates regardless of species because of the length variability of the helmets. The grazing rate of adult filter-feeding crustaceans is suggested to be approximately 7 % per day.     

Comparative vital statistics along the pastoral nomadism-sedentarism continuum

Vital statistics on pastoral nomadic and sedentarizing nomadic societies are by-and-large non-existent. Such information is highly important for both academic and policy-making reasons as pastoral nomadism as a mode of life is disappearing. This paper attempts to gather and present as much information as possible on crude birth and death rates and natural increase rates for various pastoral nomadic societies in different African and Middle Eastern countries. The information is arranged by a subdivision into nomads, seminomads, and sedentarized nomads. A summarization of this information suggests a possible pattern by which birth rates rise, death rates fall (but may rise in certain circumstances), and natural increase rates rise along the nomadism-sedentarism continuum. Such a possible pattern has several policy implications for governments assessing the needs of a nomadic society undergoing a process of change in its socio-ecological relationships.This article was written while the author was a visiting scholar at the Department of Geography at the University of California. The author wishes to thank Nga and Allen Scott and Melanine M. Patton, as well as two anonymous referees, for their assistance and suggestions for this paper.     

On the interpretation of some planktonology equations

Summary The concept of the mean value of a function is used to interpret some population-dynamics equations. The well-known formula for the per capita growth rate r gives a precise mean value for any (not only exponentially growing) populations. This result is used to derive the birth and death rate equations of Paloheimo (1974) with minimal initial limitations.Abbreviations t time - N number of animals - E number of eggs - r specific (i.e. per capita) population growth rate - b specific birth rate - d specific death rate - D duration of embryonic development