Diurnal changes of thermoregulatory functions in pigeons

In pigeons, we studied the diurnal variation of body temperatures and its dependence on the diurnal variations of shivering, vasomotor activity and panting in light-dark (LD) — conditions (1212 h, 1001 Lux) and in different, but for at least 24 h constant ambient temperatures.In low ambient temperatures (below thermoneutrality) shivering was reduced shortly after lights off (early dark phase), and it increased again some hours before lights on (late dark phase); the lower the ambient temperature, the larger the reduction of shivering and the shorter the time of reduction.Within thermoneutrality, the decrease ofT _b in the early dark phase was associated with an increase of foot skin temperature, probably due to vasodilatation. Later-on foot skin temperature decreased again (vasoconstriction). The feet remained constricted even in the late dark phase, whenT _b already increased.At higher ambient temperature (above thermoneutrality) vasodilatation persisted all over the 24 h, while in these conditions respiratory rate increased significantly after lights off.The described diurnal variations of thermoregulatory effector mechanisms are in agreement with the concept of an active adjustment of the body temperature rhythm.Supported by the Deutsche Forschungsgemeinschaft (SBF 114)     

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.     

Adrenalectomy increases local cerebral blood flow in the rat hippocampus

The present study examined the effect of glucocorticoid manipulations on local cerebral blood flow in the hippocampus. We measured local cerebral blood flow in the hippocampus at 1-h intervals over a 1-day period in freely moving rats, by means of the H₂ clearance method, before and after sham adrenalectomy, adrenalectomy or adrenalectomy with corticosterone replacement. We also measured local cerebral blood flow in the prefrontal cortex before and after adrenalectomy. Four weeks after the adrenalectomy, hippocampal blood flow at each time of day was an average of 47% greater than before the operation, showing diurnal variation as before. After the sham adrenalectomy or adrenalectomy with corticosterone replacement, hippocampal blood flow did not change significantly with respect to either its level or its diurnal variation. Local cerebral blood flow in the prefrontal cortex increased by only 19% after adrenalectomy. The present study demonstrates that adrenalectomy causes a remarkable increase in hippocampal blood flow, probably due to a lack of corticosterone.     

Electrical self-stimulation of single and multiple loci: long term observations

Rats with chronic hypothalamic electrodes were allowed continuous access to self-stimulation, food and water in a 3 lever chamber. A prolonged burst of self-stimulation, with little food and water intake, was followed by bursts of activity on all 3 levers. A 12 hr light-dark cycle imposed a diurnal periodicity on all behaviors except in animals self-stimulating at the highest daily rates where self-stimulation was equal in dark and light. Under constant light conditions there was a 30 min daily shift in the peak periodicity of all behaviors. Increasing the current by 10 μA led to another continuous self-stimulation session for one day, with a subsequent decline and stabilization after three days. Reduction of the current to its original setting abolished self-stimulation for one day, but within 5 days rates returned to control values. Animals with electrodes in the septal, anterior and posterior hypothalamic areas allowed continuous access to self-stimulation on all 3 electrodes displayed similar behavior in that after a long initial self-stimulation session alternating on all 3 electrodes, periodic bursts of activity occurred on all three electrodes. The diurnal periodicity of self-stimulation seemed to be determined by the current intensity. The similarity of self-stimulation to normal drive mechanisms is discussed.     

高血压病以昼夜血压模式指导治疗初探

目的：探讨高血压以昼夜血压模式指导药物治疗的疗效。方法：124例高血压患者被随机分为两组：观察组80例,采用以昼夜血压模式为依据,指导选用药物进行治疗,着重加强异常升高血压部份的降压治疗,同时加强血压监测;对照组仍按照常规方法治疗,6周为1疗程,治疗前和治疗后都检测血压和24小时动态血压。结果：观察组降压的总有效率和昼夜血压模式转为正常杓形态明显高于对照组,结论：高血压病患者以昼夜血压模式为依据指导用药降压治疗有较好的医疗效果。     

Day wetting

About 1% of healthy children over the age of 5 years have troublesome daytime wetting. Two-thirds of those who wet by day are reliably dry at night. The problem is more common in girls and is usually the result of urge incontinence. Although the wetting may be exacerbated by giggling and/or stress, pure giggle micturition and isolated stress incontinence are both rare. There is a strong association with bacteriuria (50% prevalence) in girls who wet by day. A potentially important relationship exists between day wetting, infection, reflux and upper tract damage, which is expressed in an extreme form in the syndromes of incoordinated voiding and progressive renal damage. Most children who wet by day have unstable bladders. Many of them adopt characteristic holding postures. There is an increased incidence of emotional disorder compared with children who merely wet the bed. Between 10% and 15% of children who wet by day become dry during the next 12 months. The acquisition of dryness is accelerated by eradication of bacteriuria and a sympathetic and energetic management regime, which should place responsibility on the child and result in the child voiding more frequently and completely. Reminder alarms and other behaviour therapies have proved effective. There is no satisfactory evidence for the efficacy of drugs. More complex behavioural training regimes including biofeedback are valuable for severe cases.     

正常眼压性青光眼确诊时各指标间病变程度的关系

目的　考察正常眼压性青光眼 (normalpressureglaucoma ,NPG)患者确诊时的临床表现 ,探讨各指标间病变程度的关系。方法　 10 5例NPG患者 ,分析眼压曲线的平均状态、波动幅度和双眼对称性 ,观察视野和眼底C/D垂直径比值、盘沿缩窄和视网膜神经纤维层 (RNFL)改变。结果　眼压曲线双眼对称 ,总体波动水平位于 16mmHg上下 ,最高值在 10AM ,最低值在 10PM ,但10PM最低值高于年龄可比的正常人群的平均眼压 (P <0 0 1)。单值眼压分布位于 10～ 2 1mmHg ,峰值与谷值相差约 4mmHg。视野在 5 5例患者为单眼损害 ,在 14 9眼的视野损害中 ,绝大多数损害形态和部位与眼压升高的原发性开角型青光眼 (hp -POAG)相符合 ,但旁中心损害侵入中心固视区者约占 2 2 % ,而在轻度损害中约占 1/3。眼底C/D值右眼为 0 77± 0 15 ,左眼为 0 71± 0 16,二者均大于一般群体上限和早期hp -POAG患者的C/D值 (P <0 0 1) ,但在不同程度损害的视野中差异不显著 (P >0 10 ) ,盘沿缩窄和RNFL缺损的发生率分别为 5 0 %以上和 60 %以上 ,二者差异不显著 (P>0 0 5 )。结论　NPG患者的眼压在绝对值、波动幅度和双眼对称性上均与正常眼压各指标相一致 ,对诊断无定性价值。确诊时眼底C/D值大于早期hp -POAG的C/D值 ,盘沿缩窄和RNFL缺损的     

豚鼠形觉剥夺性近视模型眼压昼夜节律的改变

目的 研究豚鼠形觉剥夺性近视模型眼压昼夜节律的改变,探讨眼压节律与形觉剥夺性近视形成机制的关系.方法 将出生1财的豚鼠30只单眼半透明眼罩遮盖,实验前及遮盖9周后行带状检影验光和A超测定眼轴长度,并于遮盖9周后测量24h眼压节律.结果 9周后与对照眼相比,实验眼诱导出(-6.21±2.23)D(t=-14.659,P＜0.001)的相对近视,眼轴较对照眼延长(0.48±0.23)mm (t=11.328,P＜0.001),眼压较对照眼升高(4.05±2.45)mm Hg(t=9.071,P＜0.001),24h眼压节律峰值及谷值较正常.结论 豚鼠形觉剥夺性近视模型眼压昼夜节律时相变异较正常对照眼显著,眼压昼夜节律的改变可能参与形觉剥夺性近视的形成.     

槲蕨的光合特性与环境因子的关系

目的:探索不同光照环境下槲蕨的光合作用日变化,为槲蕨的人工栽培提供理论依据。方法:利用Li-6400便携式光合测定系统测定槲蕨的光合作用日变化,并对影响其光合作用的生理因子和环境因子进行相关性分析。结果:槲蕨的净光合速率日变化呈单峰曲线,最大值出现在15∶30,日均净光合速率以树附生环境的槲蕨最高,其次是阳生环境,阴生环境的最低,对光环境的适应性较强;瞬时水分利用率与净光合速率呈极显著正相关,大气温度、CO2浓度和相对湿度是槲蕨净光合速率的主要环境影响因子。结论:人工栽培时以控制气温为32℃左右,空气相对湿度40%左右,适当遮荫最适宜。     

Diurnal blood pressure variation in the evaluation of early onset severe pre-eclampsia

OBJECTIVE: To study the association between diurnal variation in blood pressure, the mean daily blood pressure and various complications of pregnancy in patients presenting with severe pre-eclampsia before 34 weeks' gestation. STUDY DESIGN: Forty-four women presenting to a tertiary hospital in South Africa with severe pre-eclampsia between 28 and 34 weeks' gestation were managed expectantly for at least 8 days. We measured maternal blood pressure every 30 min with the pregnancy validated Spacelabs 90209 automated blood pressure monitor for 24h periods on alternative days. The mean 24-h diastolic blood pressure measurement, the mean diastolic blood pressure for daytime and nighttime, the day-night blood pressure difference and the night-day ratio were compared with the occurrence of abruptio placentae, gestational age at delivery, neonatal intensive care unit admission, birth weight, abnormal umbilical artery Doppler FVW and reason for delivery. RESULTS: One hundred and seventy-six 24-h studies were analyzed. The day-night blood pressure difference decreased with increasing mean diastolic blood pressure (r=-0.323, p<0.0001). A combination of normal mean diastolic blood pressure and normal day-night blood pressure difference was associated with increased gestational age and lower caesarean section rates. CONCLUSION: The combination of mean diastolic blood pressure and day-night blood pressure difference may be a supplementary measurement of disease severity in early onset severe pre-eclampsia and seems to be of prognostic value.