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排序方式: 共有154条查询结果,搜索用时 15 毫秒
1.
Influence of temperature on the number of Legionella pneumophila in hot water systems 总被引:1,自引:1,他引:0
The occurrence of legionella in the hot water systems of two buildings (A and B) was investigated in relation to the water temperature. The peripheral parts of both hot water systems were found to be colonized by these organisms. A temperature of 60C in the hot water mains returning from the building eliminated legionellas from the mains as well as from the peripheral taps and showers. Legionellas could be isolated from taps, showers and the mains when the temperature in the return mains was kept at 54C. The hot water systems could not be completely decontaminated by raising the hot water temperature in the return mains to 70C combined with flushing all the taps and showers. It is suggested that failure to decontaminate the systems is due to dead ends in the pipeline network, which are not reached by the hot water and that these dead ends are the source for recolonization of the systems. 相似文献
2.
Groothuis JT Thijssen DH Lenders JW Deinum J Hopman MT 《Journal of applied physiology (Bethesda, Md. : 1985)》2011,110(2):416-422
Maintaining blood pressure during orthostatic challenges is primarily achieved by baroreceptor-mediated activation of the sympathetic nervous system, which can be divided into preganglionic and postganglionic parts. Despite their preganglionic autonomic failure, spinal cord-injured individuals demonstrate a preserved peripheral vasoconstriction during orthostatic challenges. Whether this also applies to patients with postganglionic autonomic failure is unknown. Therefore, we assessed leg vasoconstriction during 60° head-up tilt in five patients with pure autonomic failure (PAF) and two patients with autonomic failure due to dopamine-β-hydroxylase (DBH) deficiency. Ten healthy subjects served as controls. Leg blood flow was measured using duplex ultrasound in the right superficial femoral artery. Leg vascular resistance was calculated as the arterial-venous pressure gradient divided by blood flow. DBH-deficient patients were tested off and on the norepinephrine pro-drug l-threo-dihydroxyphenylserine (l-DOPS). During 60° head-up tilt, leg vascular resistance increased significantly in PAF patients [0.40 ± 0.38 (+30%) mmHg·ml(-1)·min(-1)]. The increase in leg vascular resistance was not significantly different from controls [0.88 ± 1.04 (+72%) mmHg·ml(-1)·min(-1)]. In DBH-deficient patients, leg vascular resistance increased by 0.49 ± 0.01 (+153%) and 1.52 ± 1.47 (+234%) mmHg·ml(-1)·min(-1) off and on l-DOPS, respectively. Despite the increase in leg vascular resistance, orthostatic hypotension was present in PAF and DBH-deficient patients. Our results demonstrate that leg vasoconstriction during orthostatic challenges in patients with PAF or DBH deficiency is not abolished. This indicates that the sympathetic nervous system is not the sole or pivotal mechanism inducing leg vasoconstriction during orthostatic challenges. Additional vasoconstrictor mechanisms may compensate for the loss in sympathetic nervous system control. 相似文献
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Eising CM Eikenaar C Schwabl H Groothuis TG 《Proceedings. Biological sciences / The Royal Society》2001,268(1469):839-846
We tested the hypothesis that mother birds counterbalance the negative effects of hatching asynchrony for later-hatched chicks by increasing the yolk androgen concentrations in consecutive eggs of their clutch. In doing so, they may adaptively tune each offspring's competitive ability and, thus, growth and survival. However, evidence in support of this hypothesis is contradictory. The yolk concentrations of maternal androgens in the eggs of black-headed gulls increase significantly with the laying order of the eggs in a clutch. We experimentally tested the functional consequences of this increase on chick development under natural conditions by injecting eggs with either an oil or androgen solution. We created experimental clutches in which androgen levels either stayed constant or increased with laying order while controlling for differences in egg quality by using only first-laid eggs. We then compared development, growth and survival between these broods. Androgen treatment enhanced embryonic development because androgen-treated eggs hatched half a day earlier than controls, while their size at hatching was similar to oil-treated controls. Androgen treatment did not increase chick survival, but it enhanced growth. Androgen-treated, third-hatched chicks had a higher body mass and longer legs than third-hatched chicks that hatched from oil-treated eggs. At the same time, growth of first chicks (which were all oil treated) was reduced by the presence of two androgen-treated siblings, suggesting that yolk androgens enhance the competitive ability of later-hatched chicks. Our results support the hypothesis that transfer of different amounts of androgens to the eggs of a clutch is a mechanism by which mothers maximize their reproductive output. 相似文献
6.
We tested the challenge hypothesis for the hormonal regulation of aggression in chicks of the black-headed gull, Larus ridibundus. Chicks of this species are highly aggressive toward conspecifics, but never to peers that hatched from the same clutch (modal clutch size is three). Therefore, in the first experiment small families were housed together in large groups (challenged condition) and compared to families kept isolated (nonchallenged condition). As expected, in the challenged condition during the initial stage of territory establishment basal levels of testosterone (T) were clearly higher than those in the nonchallenged condition. In the second experiment we tested the effect of a short social challenge on short-term T-fluctuations. The design was based on an earlier experiment, showing that after temporary T-treatment chicks become very sensitive to social challenges while having low basal T-levels. We now show that these social challenges induce brief elevations in plasma T-levels. These peaks are similar to those in previously untreated chicks but untreated chicks do not respond with aggression to a challenge. Therefore, we conclude that the initial exposure to elevated T-levels increases the sensitivity to brief changes in T induced by social challenges. In this way exposure to T, that may be detrimental for development, is minimized while birds remain able to defend territories. This is the first report showing that the challenge hypothesis as established for adult birds, is also applicable for aggressive behavior in young birds outside the sexual context. Furthermore we suggest that a phase of priming with T is necessary to obtain the high behavioral responsiveness to a challenge. 相似文献
7.
Cécile R L Boot Jan T Groothuis Herman Van Langen Maria T E Hopman 《Journal of applied physiology》2002,92(6):2335-2340
The purpose of this study was to assess the relationship between inactivity and shear stress, the frictional force of blood against the endothelium, in spinal cord injury (SCI) subjects. SCI group offers a unique "model of nature" to study the effects of inactivity. Nine SCI subjects with upper (SCI-U) and 5 with a lower (SCI-L) motoneuron lesion and 10 able-bodied controls (C) were included. A venous blood sample was withdrawn to determine blood viscosity. Red blood cell velocities and arterial diameters of the common carotid artery (CCA) and common femoral artery (CFA) were measured by using echo-Doppler ultrasound in a supine position. No differences were observed in wall shear stress in the CCA between groups. In the CFA, peak and mean wall shear stress were significantly increased in SCI (14.1 and 1.2 Pa, respectively) compared with C (10.2 and 0.9 Pa, respectively). Because SCI-U and SCI-L showed no differences in shear stress levels, inactivity and not nerve degeneration seems to cause the elevated shear stress levels in the CFA in SCI. However, the lack of central neural control as a causal factor cannot be ruled out. 相似文献
8.
Balagopal P Pandey M Chandramohan K Somanathan T Kumar A 《World journal of surgical oncology》2003,1(1):4
Background
Choriocarcinoma is an aggressive neoplasm arising in the body of the uterus. The disease normally spreads to lung and brain. 相似文献9.
Verhoeven CH Gloudemans RH Groothuis GM Rietjens IM Vos RM 《The Journal of steroid biochemistry and molecular biology》2000,73(1-2):39-48
Metabolism of Org 30659 ((17alpha)-17-hydroxy-11-methylene-19-norpregna-4, 15-dien-20-yn-3-one), a new potent progestagen currently under clinical development by NV Organon for use in oral contraception and hormone replacement therapy, was studied in vivo after oral administration to healthy postmenopausal women. After oral administration of [14C]-Org 30659 to postmenopausal women, the compound was extensively metabolized. The dosed radioactivity was predominantly excreted via urine. Org 30659 was to a large extent metabolized at the C3- and the C17-positions. Phase II metabolism, and in particular conjugation with glucuronic acid at the 17beta-hydroxy group, is the major metabolic route for Org 30659 in vivo. Not only phase II metabolism was observed for Org 30659 after oral administration to postmenopausal volunteers, but also metabolism in the A-ring occurred, especially reduction of the 3-keto-Delta(4) moiety to give 3alpha-hydroxy, 5alpha(beta)-dihydro and 3beta-hydroxy, 5alpha-dihydro derivatives. Oxidative metabolism (6beta-hydroxylation) observed in human liver preparations in vitro, was not observed to a significant extent in vivo. So, in vitro human metabolism is different from the in vivo metabolism, indicating that the in vitro-in vivo extrapolation is far from straightforward, at least when only liver preparations are used. The proper choice of the in vitro system (e.g., microsomes, hepatocytes, slices or individually expressed enzymes) and the substrate concentration can be very important determinative factors for the predictability of the in vitro system for the in vivo situation. Species comparison of the metabolic routes of Org 30659 after oral administration indicated that the monkey seems to be a better representative species than the rat for the metabolism of Org 30659 in humans. 相似文献
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