Extensive training in a maze task reduces neurogenesis in the adult rat dentate gyrus probably as a result of stress

It has recently been shown that hippocampal neurogenesis can be modulated either directly or indirectly by ascending cholinergic inputs from the basal forebrain. In the present work, we sought to address whether extended training in a spatial navigation task would affect hippocampal neurogenesis in the presence of a severe and selective cholinergic depletion. Young female rats received stereotaxic injections of the immunotoxin 192 IgG-saporin into the basal forebrain nuclei and/or the cerebellar cortex. Starting from 4 to 5 weeks post-lesion, and for the subsequent 2 weeks, the animals were trained on paradigms of reference and working memory in the water maze and received single daily i.p. injections of bromodeoxyuridine (BrdU) at the end of each testing session. In line with previous observations, a dramatic 80% decrease in neuron proliferation was seen in the dentate gyrus of lesioned animals, as compared to vehicle-injected or intact controls. Interestingly, however, rats subjected to maze training over 2 weeks, irrespective of their learning success, exhibited significantly fewer newborn neurons than matched controls with no maze exposure. Thus, at least for the type of task used here, which has previously been shown to impose a certain degree of stress, extended training and learning does not appear to affect proliferation in the dentate gyrus.     

Effect of atropine on the bronchial response of asthmatic subjects to the inhalation of ultrasonically nebulized distilled water

To determine whether atropine provides protection against the bronchoconstriction that develops in asthmatic subjects after inhalation of ultrasonically nebulized distilled water, we exposed six asthmatic patients to this stimulus with and without pretreatment with atropine (0.04 mg/kg). The mean FEV1 decreased from 3.32 to 2.39 L (-28%) without and from 3.49 to 3.18 L (-9%) with atropine. This protective effect was statistically significant (p less than 0.05), suggesting that cholinergic pathways are involved in the obstructive response to the inhalation of ultrasonically nebulized distilled water.     

Infrared-spectrometric determination of D2O in biological fluids

The determination of D₂O in biological fluids by means of infrared spectrometry was reinvestigated. When the temperature of a solution, containing D₂O in the range from natural abundance to 5 ml·1^–1 increases, its absorbance decreases and the wavenumber of maximum absorption shifts to a higher value. Both changes are linearly related to the change in temperature. Storage for 17 d in either glass or polyethylene tubes does not affect the D₂O concentration. Purification of biological fluids by vacuum-sublimation removes all substances which also absorb at the O-D vibration band and the recovery of D₂O from plasma and urine is complete. The partition ratio of D₂O between plasma water and red cell water equals unity, and the same holds for plasma water and urine water over a wide range of urine flows and osmolalities. The arterial and urinary disappearance curves of D₂O, measured over several days, both permit the calculation of the total amount of body water (V ^bw), the daily water turn-over (F) and the half-time of water in the body (t _1/2), but the data derived from arterial disappearance curves are more precise. In 16 male mongrel dogs (25–32 kg body mass) the following results were obtained:V ^bw=626±28 ml·kg^–1,F=12.0±3.2% andt _1/2=6.21±1.78 d.     

乌拉地尔对吗啡导致的大鼠空间记忆障碍的改善作用

目的研究吗啡对大鼠空间记忆的影响和5-HT1A受体激动剂乌拉地尔对这种影响的改善作用。方法;训练大鼠学习Morris水迷宫任务,检验它们在注射药物情况下回忆空间任务的能力。结果同时注射乌拉地尔(20mg/kg)和吗啡(10mg/kg)的大鼠通过回忆寻找Morris水迷宫隐蔽站台的潜伏期(第一次测验,30.43±9.46;第二次测验,41.00±10.30;单位,秒),显著短于单独注射吗啡的动物(第一次测验,87.00±22.53;第二次测验,96.67±20.85;均为P<0.01);而与对照组动物(第一次测验,16.17±3.74;第二次测验,16.33±2.36)没有显著差别。单因素方差分析对照组和给药情况下吗啡组、吗啡-纳洛酮组和吗啡-乌拉地尔组回忆测验结果分别为第一次测验,16.17±3.74、87.00±22.53、34.67±6.75、30.43±9.46,F1(3,21)=5.866,P<0.01;第二次测验,16.33±2.36、96.67±20.85、22.17±6.46、41.00±10.30,F2(3,21)=8.94,P<0.01。结论乌拉地尔能够显著改善吗啡导致的大鼠空间记忆障碍。     

广州市1996—2005年管网末梢水卫生状况及对策分析

目的了解广州市管网末梢水的水质情况，为随时监测全市生活饮用水水质的动态变化提供信息并提出改进措施。方法对广州市1996—2005年管网末梢水水质监测资料进行统计，按照GB5749—85《生活饮用水卫生标准》和卫生部《生活饮用水卫生规范》（2001年）进行分析评价。结果共监测606份水样，合格155份，合格率为25．58％。不合格的项目主要有锰、游离余氯、细菌总数、色度、铁和耗氧量。在广州市疾病预防控制中心检测的项目中，锰的合格率仅为59．57％，游离余氯的合格率为76．73％，细菌总数的合格率为85．81％，色度的合格率为88．12％，铁的合格率为88．94％，耗氧量的合格率为96．37％。结论广州市管网末梢水的锰、游离余氯、细菌总数和铁等项目合格率较低，今后应加强饮水的氯化消毒、对管网的定期检修和冲洗、减少二次供水水箱的使用和设立管网水水质自动监测系统。     

Effects of sympathetic inhibition on blood pressure and renal responses to central hypervolaemia in normal humans

The purpose of this study was to evaluate the effects of short-term sympathetic inhibition with clonidine on blood pressure and renal responses to central hypervolaemia induced by thermoneutral head-out water immersion. Eleven healthy subjects were randomly studied on two occasions, during a 1 h pre-immersion period, 2 h of water immersion and a 1 h post-immersion period, after either placebo or clonidine treatment. Clonidine caused a significant suppression of plasma adrenaline, plasma noradrenaline, urinary noradrenaline excretion and mean arterial blood pressure. Blood pressure remained constant during water immersion after both placebo and clonidine, compared with the respective pre-immersion control values. The suppression pattern of plasma catecholamines and urinary noradrenaline in response to water immersion during placebo was similar after clonidine treatment. Renal volume excretion was not affected by clonidine. In contrast, clonidine caused a significant attenuation of the immersion-induced stimulation of natriuresis (maximum -33±12%, P<0.01, compared with placebo). These data indicate that the renal capacity to excrete sodium is impaired during moderate blood pressure reduction by short-term sympathetic inhibition with clonidine, whereas the regulation of arterial blood pressure in response to central hypervolaemia is maintained.     

Effect of early outdoor experience on the activity of wild and semi-domestic deermice

The gross activity of wild and semi-domestic strains of prairie deermice was measured in two kinds of novel test apparatus (tilt-cage and activity wheel). Differences in strain activity were not obtained in either apparatus. Activity was significantly decreased in both strains by early experience in the field and by rearing wild genotype subjects in large laboratory cages. It was suggested that differential early sensory experience associated with both qualitative and quantitative aspects of the early rearing environment may be responsible for the treatment effect. Whereas no daily changes in activity were noted in the tilt-cages, activity in the wheels was sipnificantly higher on day 1 for all groups. In contrast to recent literature, wheel running activity did not change with total water deprivation.     

Environmental risk factors for hepatitis A infection in the Zenica–Doboj Canton, Bosnia and Herzegovina

In the Zenica-Doboj Canton, 1106 hepatitis A virus (HAV) infections were reported during 2000 (an incidence rate of 252/100 000 population), with 996 (90.1%) cases occurring in nine community-wide outbreaks. Analysis of water supplies showed that 398 (19.1%) samples contained coliforms, including 202 (50.8%) that were contaminated with thermotolerant Escherichia coli. Sewage sanitation systems were absent or substandard in 53 910 (81.8%) rural households. The group most affected during outbreaks comprised children aged 7-14 years (incidence rate of 598/100 000). The development of health promotion and prevention initiatives in schools, combined with rigorous hygiene measures, will be necessary to achieve control of the spread of HAV.     

Total energy expenditure of elite synchronized swimmers measured by the doubly labeled water method

To determine the daily energy requirement of elite synchronized swimmers during moderate-intensity training, the average daily energy expenditure measured by the doubly labeled water method, was calculated for nine female Japanese national team synchronized swimmers [four senior; mean (SD) 22.5 (1.0) years old, 52.2 (3.6) kg, and five junior; 17.6 (1.1) years old, 52.8 (2.3) kg]. Their total energy expenditure (TEE) was 11.5 (2.8) MJ · day⁻¹ [2738 (672) kcal · day⁻¹]. When compared with estimated energy requirements derived from “Recommended Dietary Allowances for the Japanese”, 12.1 (0.6) MJ · day⁻¹ [2897 (139) kcal · day⁻¹], there was no difference between mean actual and estimated energy requirements. However, there were considerable differences observed on an individual basis. Their energy intake, estimated from 7- day self-reported dietary records, was 8.9 (1.7) MJ · day⁻¹ [2128 (395) kcal · day⁻¹], which was significantly lower than their TEE (P < 0.05). Resting energy expenditure (REE), as determined by indirect calorimetry, was 5.2 (0.3) MJ · day⁻¹ [1247 (75) kcal · day⁻¹]. Their physical activity level (TEE/REE) was 2.18 (0.43). These results demonstrate that the TEE values of elite female synchronized swimmers are not dissimilar to those reported for athletes participating in other sports, especially competitive swimmers during moderate-intensity training. Accepted: 26 May 2000     

Heat and water vapour transfer of protective clothing systems in a cold environment,measured with a newly developed sweating thermal manikin

A moveable sweating thermal manikin has recently been developed. Thermal and water-vapour resistances of three kinds of cold-protective clothing ensembles, laminated with polytetrafluoroethylene, polyurethane and without a laminate were measured, with the aid of the manikin in a cold environment of 5°C with a relative humidity of 70% and an air velocity of around 1.5 m s^–1. Two sweating rates of 65 and 130 g m^–2 h^–1 were employed. Supplied heat fluxes in both of the sweat rates ranged from 350 W m^–2 to 400 W m^–2. To maintain a comfortable condition, the skin wettedness (w) (mean weighted value) had to be kept at 0.6. The measurements obtained from the manikin when testing the three ensembles were w=0.3 (approximately) for the low sweat rate and w0.6 for the high sweat rate, irrespective of the property differences among the ensembles. In addition, the condensation in the ensembles in comparison with those calculated from an analytical equation is discussed. Condensation mass fluxes in the ensembles obtained byexperiment and those from the calculation agreed sufficiently well. Thus, distribution of the condensation in the ensembles was estimated using the equation.