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1.
The change in peripheral sweating mechanisms of the tropical Malaysian who stays in Japan 总被引:1,自引:0,他引:1
Jeong-Beom Lee Jun-Sang Bae Mi-Young Lee Hun-Mo Yang Young-Ki Min Ho-Yeon Song Kwang-Kyune Ko Jun-Tack Kwon Takaaki Matsumoto 《Journal of thermal biology》2004,29(7-8):743-747
Tropical subjects regulate core temperature with less amount of sweat against heat compared to temperate subjects through long-term heat-acclimatization. The purpose of the study is to determine whether acclimatization in tropical subjects decay during a stay in temperate area. The aim of this study, therefore, was to investigate the possible changes in the peripheral sweating mechanisms. Local sweating response activated by acetylcholine (ACh) applied iontophoretically among Malaysians with varying duration of stay in Japan and Japanese resident subjects. Directly activated (DIR) and axon reflex (AXR)-mediated sweating during ACh iontophoresis were measured by capacitance hygrometer (quantitative sudomotor axon reflex test, QSART) QSART was performed in a thermoneutral condition (24±0.5 °C, 40±3% rh). The sweat onset-time after the current loading was 1.05 min shorter in Malaysian with long-term stay in Japan (MLJ) than in Malaysian, and the AXR(1), AXR(2) and DIR sweating in MLJ were larger than Malaysian. From these results, suppressed neuroglandular response to ACh was confirmed in Malaysians. It is suggested that long-term heat-acclimatization acquired in tropical subjects may decay after immigration to temperate area. 相似文献
2.
Relatively few studies have investigated peripheral sweating mechanisms of long-distance runners. The aim of this study was to compare peripheral sweating mechanisms in male long-distance runners, and sedentary counterparts. Thirty six subjects, including 20 sedentary controls and 16 long-distance runners (with 7–12 years of athletic training, average 9.2±2.1 years) were observed. Quantitative sudomotor axon reflex testing (QSART) with iontophoresis (2 mA for 5 min) and 10% acetylcholine (ACh) were performed to determine axon reflex-mediated and directly activated (DIR, muscarinic receptor) sweating. Sweat onset time, sweat rate, number of activated sweat glands, sweat output per gland and skin temperature were measured at rest while maximum oxygen uptake (VO2max) were measured during maximal cycling. Sweat rate, activated sweat glands, sweat output per gland, skin temperature and VO2max were significantly higher in the trained runners than in the sedentary controls. Sweat onset time was significantly shorter for the runners. In the group of long-distance runners, significant correlations were found between VO2max and sweat onset time (r2 = 0.543, P<0.01, n = 16), DIR sweat rate (r2 = 0.584, P<0.001, n = 16), sweat output per gland (r2 = 0.539, P<0.01, n = 16). There was no correlation between VO2max and activated sweat glands. These findings suggest that habitual long-distance running results in upregulation of the peripheral sweating mechanisms in humans. Additional research is needed to determine the molecular mechanism underlying these changes. These findings complement the existing sweating data in long-distance runners. 相似文献
3.
Yoshimitsu Inoue Tomoko Ichinose-Kuwahara Chie Funaki Hiroyuki Ueda Yutaka Tochihara Narihiko Kondo 《Journal of physiological anthropology》2014,33(1):13
Purpose
The present study examined sex differences in the sweat gland response to acetylcholine (ACh) in physically trained and untrained male and female subjects.Methods
Sweating responses were induced on the forearm and thigh in resting subjects by ACh iontophoresis using a 10% solution at 2 mA for 5 min at 26°C and 50% relative humidity.Results
The ACh-induced sweating rate (SR) on the forearm and thigh was greater in physically trained male (P < 0.001 for the forearm and thigh, respectively) and female (P = 0.08 for the forearm, P < 0.001 for the thigh) subjects than in untrained subjects of both sexes. The SR was also significantly greater in physically trained males compared to females at both sites (P < 0.001) and in untrained males compared to females on the thigh (P < 0.02) only, although the degree of difference was greater in trained subjects than in untrained subjects. These sex differences can be attributed to the difference in sweat output per gland rather than the number of activated sweat glands.Conclusion
We conclude that physical training enhances the ACh-induced SR in both sexes but that the degree of enhancement is greater in male than in female subjects. The effects of physical training and sex on the SR may be due to changes in peripheral sensitivity to ACh and/or sweat gland size. 相似文献4.
A. J. Allsopp R. Sutherland P. Wood S. A. Wootton 《European journal of applied physiology and occupational physiology》1998,78(6):516-521
The effect of manipulating sodium intake upon sweat sodium secretion was investigated during heat acclimation. Twenty-five
male subjects were confined to an environmental chamber at a temperature of 25°C for 3 days, and then acclimated to heat by
a further 5 days at 40°C. The subjects' daily sodium intake was controlled throughout as follows: high (HNa), 348.4 (0.8) mmol · day−1, n = 7; moderate (MNa), 174.1 (0.6) mmol · day−1, n = 9; or low (LNa), 66.3 mmol · day−1, n = 9. Sodium losses were estimated from urinary, faecal and sweat collections using a whole-body washdown method. Plasma aldosterone
concentration was also measured from venous blood sampled each morning. Measurements of body temperature and heart rate during
the heat exposure phase indicated a degree of heat acclimation. During this heat phase there was a reduction (P < 0.01) in sweat sodium secretion for all three conditions which was greatest for the LNa condition, although this finding
was not significant (P < 0.1). In the LNa condition, plasma aldosterone concentration increased (P < 0.05) prior to heat exposure, and the secretion of aldosterone was potentiated (P < 0.01) during the heat exposure in comparison with the MNa condition. In contrast, the HNa diet produced a fall (P < 0.05) in plasma aldosterone concentration prior to heat exposure and an attenuation of aldosterone secretion thereafter.
These findings are inconsistent with the hypothesis that retention of sweat sodium is dependent upon a net body sodium deficit,
but demonstrate that aldosterone secretion is potentiated under such conditions.
Accepted: 22 May 1988 相似文献
5.
Contribution of central versus sweat gland mechanisms to the seasonal change of sweating function in young sedentary males and females 总被引:1,自引:0,他引:1
Yumiko Taniguchi Junichi Sugenoya Naoki Nishimura Satoshi Iwase Takaaki Matsumoto Yuuki Shimizu Yoko Inukai Maki Sato 《International journal of biometeorology》2011,55(2):203-212
In summer and winter, young, sedentary male (N = 5) and female (N = 7) subjects were exposed to heat in a climate chamber in which ambient temperature (Ta) was raised continuously from 30
to 42°C at a rate of 0.1°C min−1 at a relative humidity of 40%. Sweat rates (SR) were measured continuously on forearm, chest and forehead together with tympanic
temperature (Tty), mean skin temperature ( [`T] s ) \left( {\overline {\hbox{T}} {\hbox{s}}} \right) and mean body temperature ( [`T] b ) \left( {\overline {\hbox{T}} {\hbox{b}}} \right) . The rate of sweat expulsions (Fsw) was obtained as an indicator of central sudomotor activity. Tty and ( [`T] b ) \left( {\overline {\hbox{T}} {\hbox{b}}} \right) were significantly lower during summer compared with winter in males; SR was not significantly different between summer and
winter in males, but was significantly higher during summer in females; SR during winter was higher in males compared with
females. The regression line relating Fsw to ( [`T] b ) \left( {\overline {\hbox{T}} {\hbox{b}}} \right) shifted significantly from winter to summer in males and females, but the magnitude of the shift was not significantly different
between the two subject groups. The regression line relating SR to Fsw was steepened significantly from winter to summer in
males and females, and the change in the slope was significantly greater in females than in males. Females showed a lower
slope in winter and a similar slope in summer compared to males. It was concluded that sweating function was improved during
summer mediated by central sudomotor and sweat gland mechanisms in males and females, and, although the change of sweat gland
function from winter to summer was greater in females as compared with males, the level of increased sweat gland function
during summer was similar between the two subject groups. 相似文献
6.
Bronislaw A. Zachara Jolanta Gromadzinska Jadwiga Palus Zbigniew Zbrog Rafal Swiech Ewa Twardowska Wojciech Wasowicz 《Biological trace element research》2011,142(3):274-283
Patients with chronic kidney disease (CKD) have an increased incidence of cancer. It is well known that long periods of hemodialysis
(HD) treatment are linked to DNA damage due to oxidative stress. In this study, we examined the effect of selenium (Se) supplementation
to CKD patients on HD on the prevention of oxidative DNA damage in white blood cells. Blood samples were drawn from 42 CKD
patients on HD (at the beginning of the study and after 1 and 3 months) and from 30 healthy controls. Twenty-two patients
were supplemented with 200 μg Se (as Se-rich yeast) per day and 20 with placebo (baker's yeast) for 3 months. Se concentration
in plasma and DNA damage in white blood cells expressed as the tail moment, including single-strand breaks (SSB) and oxidative
bases lesion in DNA, using formamidopyrimidine glycosylase (FPG), were measured. Se concentration in patients was significantly
lower than in healthy subjects (P < 0.0001) and increased significantly after 3 months of Se supplementation (P < 0.0001). Tail moment (SSB) in patients before the study was three times higher than in healthy subjects (P < 0.01). After 3 months of Se supplementation, it decreased significantly (P < 0.01) and was about 16% lower than in healthy subjects. The oxidative bases lesion in DNA (tail moment, FPG) of HD patients
at the beginning of the study was significantly higher (P < 0.01) compared with controls, and 3 months after Se supplementation it was 2.6 times lower than in controls (P < 0.01). No changes in tail moment was observed in the placebo group. In conclusion, our study shows that in CKD patients
on HD, DNA damage in white blood cells is higher than in healthy controls, and Se supplementation prevents the damage of DNA. 相似文献
7.
Six Angus steers (319 ± 8.5 kg) were assigned to one of two groups (hot or cold exposure) of three steers each, and placed
into two environmental chambers initially maintained at 16.5–18.8°C air temperature (T
a). Cold chamber T
a was lowered to 8.4°C, while T
a within the hot chamber was increased to 32.7°C over a 24-h time period. Measurements included respiration rate, and air and
body (rectal and skin) temperatures. Skin temperature was measured at shoulder and rump locations, with determination of sweat
rate using a calibrated moisture sensor. Rectal temperature did not change in cold or hot chambers. However, respiration rate
nearly doubled in the heat (P < 0.05), increasing when T
a was above 24°C. Skin temperatures at the two locations were highly correlated (P < 0.05) with each other and with T
a. In contrast, sweat rate showed differences at rump and shoulder sites. Sweat rate of the rump exhibited only a small increase
with T
a. However, sweat rate at the shoulder increased more than four-fold with increasing T
a. Increased sweat rate in this region is supported by an earlier report of a higher density of sweat glands in the shoulder
compared to rump regions. Sweat rate was correlated with several thermal measurements to determine the best predictor. Fourth-order
polynomial expressions of short-term rectal and skin temperature responses to hot and cold exposures produced r values of 0.60, 0.84, and 0.98, respectively. These results suggest that thermal inputs other than just rectal or skin temperature
drive the sweat response in cattle. 相似文献
8.
Titis Wijayanto Hitoshi Wakabayashi Joo-Young Lee Nobuko Hashiguchi Mohamed Saat Yutaka Tochihara 《International journal of biometeorology》2011,55(4):491-500
The objective of this study was to investigate thermoregulatory responses to heat in tropical (Malaysian) and temperate (Japanese)
natives, during 60 min of passive heating. Ten Japanese (mean ages: 20.8 ± 0.9 years) and ten Malaysian males (mean ages:
22.3 ± 1.6 years) with matched morphological characteristics and physical fitness participated in this study. Passive heating
was induced through leg immersion in hot water (42°C) for 60 min under conditions of 28°C air temperature and 50% RH. Local
sweat rate on the forehead and thigh were significantly lower in Malaysians during leg immersion, but no significant differences
in total sweat rate were observed between Malaysians (86.3 ± 11.8 g m−2 h−1) and Japanese (83.2 ± 6.4 g m−2 h−1) after leg immersion. In addition, Malaysians displayed a smaller rise in rectal temperature (0.3 ± 0.1°C) than Japanese
(0.7 ± 0.1°C) during leg immersion, with a greater increase in hand skin temperature. Skin blood flow was significantly lower
on the forehead and forearm in Malaysians during leg immersion. No significant different in mean skin temperature during leg
immersion was observed between the two groups. These findings indicated that regional differences in body sweating distribution
might exist between Malaysians and Japanese during heat exposure, with more uniform distribution of local sweat rate over
the whole body among tropical Malaysians. Altogether, Malaysians appear to display enhanced efficiency of thermal sweating
and thermoregulatory responses in dissipating heat loss during heat loading. Thermoregulatory differences between tropical
and temperate natives in this study can be interpreted as a result of heat adaptations to physiological function. 相似文献
9.
Behaviour of interleukin-2 serum levels in advanced non-small-cell lung cancer patients: relationship with response to therapy and survival 总被引:8,自引:0,他引:8
Orditura M Romano C De Vita F Galizia G Lieto E Infusino S De Cataldis G Catalano G 《Cancer immunology, immunotherapy : CII》2000,49(10):530-536
Interleukin(IL)-2 is a T helper (Th) 1 type cytokine that has been shown to play an important role in antitumour immune responses.
In this study, the prognostic significance of serum IL-2 levels was investigated in 60 advanced non-small-cell lung cancer
(NSCLC) patients. IL-2 serum levels were determined before chemotherapy, at the end of chemotherapy and during follow-up,
using a commercially available enzyme-linked immunoadsorbent assay kit. The results were analysed according to the response
to therapy and were used to generate a model predicting overall survival and time to treatment failure. All 60 patients were
shown to have higher IL-2 serum levels than controls (P < 0.0001). Stage IV patients had significantly lower IL-2 levels than stage III patients (P < 0.0001), although they were still significantly higher than controls (P < 0.0001). It is interesting that, when patients were divided into responders and non-responders according to the response
to therapy, the former were shown to have significantly higher pre-chemotherapy levels than the latter (P < 0.0001). Moreover, a further significant increase in IL-2 serum levels (P=0.004) and a significant decrease (P < 0.0001) were shown in responders and non-responders, respectively at the end of the therapy. Using univariate and multivariate
analyses, both overall survival and time to treatment failure were shown to be affected by the mean pathological levels of
IL-2. Furthermore, the prognostic significance of the serum level of IL-2 was confirmed by the stepwise regression analysis.
In conclusion, determination of pre-treatment IL-2 serum levels was shown to be of independent prognostic utility in patients
with advanced NSCLC; therefore, its possible use for prediction of outcome is proposed.
Received: 16 March 2000 / Accepted: 27 July 2000 相似文献
10.
S. Dikmen L. Martins E. Pontes P. J. Hansen 《International journal of biometeorology》2009,53(4):327-331
We compared diurnal patterns of vaginal temperature in lactating cows under grazing conditions to evaluate genotype effects
on body temperature regulation. Genotypes evaluated were Holstein, Jersey, Jersey × Holstein and Swedish Red × Holstein. The
comparison of Holstein and Jersey versus Jersey × Holstein provided a test of whether heterosis effects body temperature regulation.
Cows were fitted with intravaginal temperature recording devices that measured vaginal temperature every 15 min for 7 days.
Vaginal temperature was affected by time of day (P < 0.0001) and genotype × time (P < 0.0001) regardless of whether days in milk and milk yield were used as covariates. Additional analyses indicated that the
Swedish Red × Holstein had a different pattern of vaginal temperatures than the other three genotypes (Swedish Red × Holstein
vs others × time; P < 0.0001) and that Holstein and Jersey had a different pattern than Jersey × Holstein [(Holstein + Jersey vs Jersey × Holstein)
× time, P < 0.0001]. However, Holstein had a similar pattern to Jersey [(Holstein vs Jersey) × time, P > 0.10]. These genotype × time interactions reflect two effects. First, Swedish Red × Holstein had higher vaginal temperatures
than the other genotypes in the late morning and afternoon but not after the evening milking. Secondly, Jersey × Holstein
had lower vaginal temperatures than other genotypes in the late morning and afternoon and again in the late night and early
morning. Results point out that there are effects of specific genotypes and evidence for heterosis on regulation of body temperature
of lactating cows maintained under grazing conditions and suggest that genetic improvement for thermotolerance through breed
choice or genetic selection is possible. 相似文献
11.
Exercise- and methylcholine-induced sweating responses in older and younger men: effect of heat acclimation and aerobic fitness 总被引:2,自引:0,他引:2
Inoue Y Havenith G Kenney WL Loomis JL Buskirk ER 《International journal of biometeorology》1999,42(4):210-216
The purpose of this investigation was to examine the effects of aging and aerobic fitness on exercise- and methylcholine-induced
sweating responses during heat acclimation. Five younger [Y group – age: 23±1 (SEM) years; maximal oxygen consumption (V.O2max): 47±3 ml·kg–1·min–1], four highly fit older (HO group – 63±3 years; 48±4 ml·kg–1·min–1) and five normally fit older men (NO group – 67±3 years; 30±1 ml·kg–1·min–1) who were matched for height, body mass and percentage fat, were heat acclimated by daily cycle exercise (≈35% V.O2max for 90 min) in a hot (43°C, 30% RH) environment for 8 days. The heat acclimation regimen increased performance time, lowered
final rectal temperature (T
re) and percentage maximal heart rate (%HRmax), improved thermal comfort and decreased sweat sodium concentration similarly in all groups. Although total body sweating
rates (M.sw) during acclimation were significantly greater in the Y and HO groups than in the NO group (P<0.01) (because of the lower absolute workload in the NO group), the M.sw did not change in all groups with the acclimation sessions. Neither were local sweating rates (m.
sw) on chest, back, forearm and thigh changed in all groups by the acclimation. The HO group presented greater forearm m.
sw (30–90 min) values and the Y group had greater back and thigh m.
sw (early in exercise) values, compared to the other groups (P<0.001). In a methylcholine injection test on days immediately before and after the acclimation, the order of sweat output
per gland (SGO) on chest, back and thigh was Y>HO>NO, and on the forearm Y=HO>NO. No group differences were observed for activated
sweat gland density at any site. The SGO at the respective sites increased in the post-acclimation test regardless of group
(P<0.01), but on the thigh the magnitude of the increase was lower in the NO (P<0.02) and HO (P=0.07) groups than in the Y group. These findings suggest that heat tolerance and the improvement with acclimation are little
impaired not only in highly fit older but also normally fit older men, when the subjects exercised at the same relative exercise
intensity. Furthermore, the changes induced by acclimation appear associated with an age-related decrease in V.O2max. However methylcholine-activated SGO and the magnitude of improvement of SGO with acclimation are related not only to V.O2max but also to aging, suggesting that sensitivity to cholinergic stimulation decreases with aging.
Received: 8 May 1998/Accepted: 5 October 1998 相似文献
12.
Ole Rintek Madsen Ulrik Birk Lauridsen Andreas Hartkopp Ole Helmer S?rensen 《European journal of applied physiology and occupational physiology》1997,75(3):239-245
Dual energy x-ray absorptiometry (DEXA) offers the possibility of assessing regional soft tissue composition, i.e. lean mass (LM) and fat
mass : LM may be considered a measure of muscle mass. We examined age-related differences in LM, percentage fat (%fat) and
muscle strength in 100 healthy non-athletic women aged 18–87 years. Relationships between muscle strength and leg LM in 20
elite female weight lifters and in 18 inactive women with previous hip fractures were also studied. The LM and %fat of the
whole body, trunk, arms and legs were derived from a whole body DEXA scan. Isokinetic knee extensor strength (KES) and flexor
strength (KFS) at 30° · s–1 were assessed using an isokinetic dynamometer. The women aged 71–87 years had 35% lower KES and KFS than the women aged 18–40
years (P < 0.0001). Differences in LM were less pronounced. The LM of the legs, for instance, was 15% lower in the old than in the
young women (P < 0.0001). In a multiple regression analysis with age, body mass, height and leg LM or KES as independent variables and KES
or leg LM as the dependent variable, age was the most important predictor of KES (r
partial = −0.74, P < 0.0001). The same applied to KFS. Body mass, not age, was the most important predictor of leg LM (r
partial = 0.65, P < 0.0001) and of LM at all other measurement sites. The LM measured at different regions decreased equally with increasing
age. The KES:leg LM ratio was negatively correlated with age (r = −0.70, P < 0.0001). The weight lifters had significantly higher KES:leg LM ratios than age-matched controls (+12%, P < 0.0001) and vice versa for the women with previous hip fractures (–36%, P < 0.0001). In conclusion, from our study it would seem that in healthy nonathletic women, age is a more important determinant
of muscle strength than is LM as measured by DEXA. Muscle strengthening exercises and inactivity seem to have a considerably
stronger influence on muscle strength than on LM.
Accepted: 27 August 1996 相似文献
13.
When exposed to high ambient temperatures, mammals lose heat evaporatively by either sweating from glands in the skin or by respiratory panting. Like other camelids, alpacas are thought to evaporate more water by sweating than panting, despite a thick fleece, unlike sheep which mostly pant in response to heat stress. Alpacas were brought to Australia to develop an alternative fibre industry to sheep wool. In Australia, alpacas can be exposed to ambient temperatures higher than in their native South America. As a young industry there is a great deal of variation in the quality and quantity of the fleece produced in the national flock. There is selection pressure towards animals with finer and denser fleeces. Because the fibre from secondary follicles is finer than that from primary follicles, selecting for finer fibres might alter the ratio of primary and secondary follicles. In turn the selection might alter sweat gland density because the sweat glands are associated with the primary follicle. Skin biopsy and fibre samples were obtained from the mid-section of 33 Huacaya alpacas and the skin sections were processed into horizontal sections at the sebaceous gland level. Total, primary, and secondary follicles and the number of sweat gland ducts were quantified. Fibre samples from each alpaca were further analysed for mean fibre diameter. The finer-fibred animals had a higher total follicle density (P<0.001) and more sweat glands (P<0.001) than the thicker-fibred animals. The fibre diameter and total follicle density were negatively correlated (R2=0.56, P<0.001). Given that the finer-fibred animals had higher follicle density and more sweat glands than animals with thicker fibres, we conclude that alpacas with high follicle density should not be limited for potential sweating ability. 相似文献
14.
Scott L Davis Thad E Wilson Jamie M Vener Craig G Crandall Jack H Petajan Andrea T White 《Journal of applied physiology》2005,98(5):1740-1744
This investigation tested the hypothesis that cholinergic sweat function of individuals with multiple sclerosis (MS) (MS-Con; n = 10) is diminished relative to matched healthy control subjects (Con; n = 10). In addition, cholinergic sweat function was determined before and after 15 wk of aerobic training in a subgroup of individuals with MS (MS-Ex; n = 7). Cholinergic sweating responses were assessed via pilocarpine iontophoresis on ventral forearm skin. A collection disk placed over the stimulated area collected sweat for 15 min. Sweat rate (SR) was calculated by dividing sweat collector volume by collection area and time. Iodine-treated paper was applied to the stimulated area to measure number of activated sweat glands (ASG). Sweat gland output (SGO) was calculated by dividing SR by density of glands under the collector. Sweat gland function was determined in MS-Ex to test the hypothesis that exercise training would increase sweating responses. No differences in ASG were observed between MS-Con and Con. SR and SGO in MS-Con [0.18 mg.cm(-2).min(-1) (SD 0.08); 1.74 microg.gland(-1).min(-1) (SD 0.79), respectively] were significantly lower (P < or = 0.05) than in Con [0.27 mg.cm(-2).min(-1) (SD 0.10); 2.43 microg.gland(-1).min(-1) (SD 0.69)]. Aerobic exercise training significantly (P < or = 0.05) increased peak aerobic capacity in MS-Ex [1.86 (SD 0.75) vs. 2.10 (SD 0.67) l/min] with no changes in ASG, SR, and SGO. Sweat gland function in individuals with MS is impaired relative to healthy controls. Fifteen weeks of aerobic training did not increase stimulated sweating responses in individuals with MS. Diminished peripheral sweating responses may be a consequence of impairments in autonomic control of sudomotor function. 相似文献
15.
Jesús Villanueva Marisol Soria Carlos González-Haro Laura Ezquerra José L. Nieto Jesús F. Escanero 《Biological trace element research》2011,142(3):398-406
The purpose of this study was to assess the effects of oral iron supplementation on hematological and iron metabolism in elite
soccer players. Thirty-five members of the Real Zaragoza SAD soccer team took part in this study: group A (GA, n = 24; Spanish Premier League) took an oral iron supplement of 80 mg day−1 for 3 weeks, and group B (GB, n = 11; Spanish Third Division League) did not receive any supplementation. In GA, the parameters were measured before and
after giving the iron supplements, while in GB, measurements were only made at the time of collecting the second set of data
from GA. After supplementation, GA showed an increase in serum iron (SI) (P < 0.05), serum ferritin (Ftn) (P < 0.01), and transferrin saturation (Sat) (P < 0.01) with respect to the basal values. In addition, GA showed higher values of hematocrit (P < 0.01), mean corpuscular volume (P < 0.01), Ftn (P < 0.01), and Sat (P < 0.01) than GB. No significant differences were found in any other parameters. More specifically, a higher percentage of
players had Ftn levels above upper limits in GA vs. GB (P < 0.05), and GB had a higher incidence of Ftn below lower limits with respect to subjects in GA (P < 0.01). Further, after treatment, 58.3% of GA had >800 mg of SI, while all players in GB presented levels below the lower
limits. In conclusion, iron supplementation with 80 mg·day−1 for 3 weeks, before the start of the soccer season, can be recommended for elite soccer players. 相似文献
16.
Screening of Venlafaxine Hydrochloride for Transdermal Delivery: Passive Diffusion and Iontophoresis
The objective of the study was to investigate in vitro transdermal delivery of venlafaxine hydrochloride across the pigskin by passive diffusion and iontophoresis. For passive
diffusion, experiments were carried out in Franz diffusion cell whereas for iontophoretic permeation, the diffusion cell was
modified to contain both the donor and return electrode on the same side of skin. Anodal iontophoresis was carried out using
a current density of 0.5 mA/cm2. Donor concentrations used were 585.5 mg/ml (saturated solution) and 100 mg/ml. Experiments initially performed to determine
the transport efficiency of venlafaxine ions showed promising results. Iontophoresis increased the permeation rate at both
concentration levels over their passive counterparts (P < 0.01), but surprisingly higher steady-state flux was obtained from lower donor drug load (P < 0.01). The favorable pH of the unsaturated solutions is suggested to be the cause for this effect. Mild synergistic effect
was observed when iontophoresis was carried out incorporating peppermint oil in the donor but the same was not found in passive
diffusion. Highest steady-state flux obtained in the experiment was 3.279 μmol/cm2/h when peppermint oil (0.1%) was included in the donor. As the maintenance requirement of venlafaxine hydrochloride is approximately
9.956 μmol/h, the results suggested that the drug is a promising candidate for iontophoretic delivery. 相似文献
17.
Joseph J. Hendricks John D. Aber Knute J. Nadelhoffer Richard D. Hallett 《Ecosystems》2000,3(1):57-69
Nitrogen controls on fine root substrate quality (that is, nitrogen and carbon-fraction concentrations) were assessed using
nitrogen availability gradients in the Harvard Forest chronic nitrogen addition plots, University of Wisconsin Arboretum,
Blackhawk Island, Wisconsin, and New England spruce-fir transect. The 27 study sites encompassed within these four areas collectively
represented a wide range of nitrogen availability (both quantity and form), soil types, species composition, aboveground net
primary production, and climatic regimes. Changes in fine root substrate quality among sites were most frequently and strongly
correlated with nitrate availability. For the combined data set, fine root nitrogen concentration increased (adjusted R
2 = 0.46, P < 0.0001) with increasing site nitrate availability. Fine root “extractive” carbon-fraction concentrations decreased (adjusted
R
2 = 0.32, P < 0.0002), “acid-soluble” compounds increased (adjusted R
2 = 0.35, P < 0.0001), and the “acid-insoluble” carbon fraction remained relatively high and stable (combined mean of 48.7 ± 3.1% for
all sites) with increasing nitrate availability. Consequently, the ratio of acid-insoluble C–total N decreased (adjusted R
2 = 0.40, P < 0.0001) along gradients of increasing nitrate availability. The coefficients of determination for significant linear regressions
between site nitrate availability and fine root nitrogen and carbon-fraction concentrations were generally higher for sites
within each of the four study areas. Within individual study sites, tissue substrate quality varied between roots in different
soil horizons and between roots of different size classes. However, the temporal variation of fine root substrate quality
indices within specific horizons was relatively low. The results of this study indicate that fine root substrate quality increases
with increasing nitrogen availability and thus supports the substrate quality component of a hypothesized conceptual model
of nitrogen controls on fine root dynamics that maintains that fine root production, mortality, substrate quality, and decomposition
increase with nitrogen availability in forest ecosystems in a manner that is analogous to foliage. 相似文献
18.
Nigel A. S. Taylor Mark J. Patterson James D. Cotter Duncan J. Macfarlane 《European journal of applied physiology and occupational physiology》1997,76(4):380-386
The influence of artificially induced anaemia on thermal strain was evaluated in trained males. Heat stress trials (38.6°C,
water vapour pressure 2.74 kPa) performed at the same absolute work rates [20 min of seated rest, 20 min of cycling at 30%
peak aerobic power (V˙O2peak), and 20 min cycling at 45% V˙O2peak] were completed before (HST1) and 3–5 days after 3 units of whole blood were withdrawn (HST2). Mild anaemia did not elevate
thermal strain between trials, with auditory canal temperatures terminating at 38.5°C [(0.16), HST1] and 38.6°C [(0.13), HST2;
P > 0.05]. Given that blood withdrawal reduced aerobic power by 16%, this observation deviates from the close association often
observed between core temperature and relative exercise intensity. During HST2, the absolute and integrated forearm sweat
rate (m˙
sw) exceeded control levels during exercise (P < 0.05), while a suppression of forehead m˙
sw occurred (P < 0.05). These observations are consistent with a possible peripheral redistribution of sweat secretion. It was concluded
that this level of artificially induced anaemia did not impact upon heat strain during a 60-min heat stress test.
Accepted: 17 April 1997 相似文献
19.
Ozkaya M Sahin M Cakal E Gisi K Bilge F Kilinc M 《Biological trace element research》2009,128(2):144-151
The present study was conducted to evaluate the serum selenium levels in first-degree relatives of diabetic patients (FDR)
according to controls. Insulin resistance, serum lipid levels, inflammation markers, and blood pressure were also studied
in these patients. Serum levels of selenium in FDR were significantly lower than control group (74.65 ± 5.9 vs 88.7 ± 8.7 μg/dl,
p < 0.0001). HsCRP, HOMA-IR, insulin, homocysteine levels were significantly higher in FDR according to the control group (1.32 ± 0.9
vs 0.63 ± 0.4 mg/dL, p < 0.0001; 2.07 ± 0.84 vs 1.51 ± 0.69, p < 0.0001; 9.26 ± 3.8 vs 6.8 ± 2.98 μU/MI, p < 0.0001; 15.7 ± 7.4 vs 11.5 ± 5.1 μmol/L, p < 0.0001, respectively). There was significant correlation between selenium levels and hsCRP (r = − 0.450, p < 0.0001). There was also weak significant correlation also between HOMA-IR and selenium levels (r = −0.227, p = 0.003). There was a correlation between systolic blood pressure and BMI (r = 0.365, p < 0.0001). But there was no correlation between selenium levels and blood pressure or other parameters. HsCRP, HOMA-IR, homocysteine
levels in individuals with selenium levels < 80 μg/L (n = 78) was significantly higher than hsCRP HOMA-IR, homocysteine levels in individuals with selenium levels ≥ 80 (n = 91; 1.23 ± 0.98 vs 0.81 ± 0.76 mg/dL, p < 0.003; 1.99 ± 0.88 vs 1.64 ± 0.74, p < 0.005; 15.0 ± 7.6 vs 12.9 ± 5.7 μmol/L, p < 0.049, respectively). Selenium deficiency may contribute to cardiovascular disease risk in FDR. 相似文献
20.
A.-W. Pan J. He Y. Kinouchi Hisao Yamaguchi Hiroshi Miyamoto 《European journal of applied physiology and occupational physiology》1997,75(5):388-395
The present study investigated the mechanism of diving bradycardia. A group of 14 healthy untrained male subjects were examined
during breath-holding either out of the water (30–33°C), in head-out immersion, or in whole-body submersion (27–29°C) in a
diving pool. Blood velocity, blood volume flow in the carotid artery, diastolic blood pressure and electrocardiogram were
measured and recorded during the experiments. The peak blood velocity increased by 13.6% (P < 0.01) and R-wave amplitude increased by 57.1% (P < 0.005) when the subjects entered water from air. End-diastolic blood velocity in the carotid artery increased significantly during breath-holding, e.g. increased from 0.20 (SD 0.02) m · s−1 at rest to 0.33 (SD 0.04) m · s−1 (P < 0.001) at 50.0 s in breath-hold submersion to a 2.0-m depth. Blood volume flow in the carotid artery increased by 26.6%
(P < 0.05) at 30 s and 36.6% (P < 0.001) at 40 s in breath-hold submersion to a 2.0-m depth. Diastolic blood pressure increased by 15.4% (P < 0.01) at 60 s during breath-holding in head-out immersion. Blood volume flow, and diastolic blood pressure increased significantly more and faster during breath-holding in submersion than out of the
water. There was a good negative correlation with the heart rate: the root mean square correlation coefficient r was 0.73 (P < 0.001). It was concluded that an increased accumulation of blood in the aorta and arteries at end-diastole and decreased
venous return, caused by an increase in systemic peripheral resistance during breath-holding, underlies diving bradycardia.
Accepted: 22 November 1996 相似文献