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1.
The effect of bombesin (5 ng/kg/min X 2.5 h) on basal pituitary secretion as well as on the response to thyrotropin releasing hormone (TRH; 200 micrograms) plus luteinizing hormone releasing hormone (LHRH; 100 micrograms) was studied in healthy male volunteers. The peptide did not change the basal level of growth hormone (GH), prolactin, thyroid-stimulating hormone (TSH), luteinizing hormone (LH) and follicle-stimulating hormone (FSH). On the contrary, the pituitary response to releasing hormones was modified by bombesin administration. When compared with control (saline) values, prolactin and TSH levels after TRH were lower during bombesin infusion, whereas LH and FSH levels after LHRH were higher. Thus bombesin affects in man, as in experimental animals, the secretion of some pituitary hormones. 相似文献
2.
Michael S. Conley Michael H. Stone Michael Nimmons G. A. Dudley 《European journal of applied physiology and occupational physiology》1997,75(5):443-448
This study examined hypertrophy after head extension resistance training to assess which muscles of the complicated cervical
neuromuscular system were used in this activity. We also determined if conventional resistance exercises, which are likely
to evoke isometric action of the neck, induce generalized hypertrophy of the cervical muscle. Twenty-two active college students
were studied. [mean (SE) age, weight and height: 21 (1) years, 71 (4) kg and 173 (3) cm, respectively]. Subjects were assigned
to one of three groups: RESX (head extension exercise and other resistance exercises), RES (resistance exercises without specific
neck exercise), or CON (no training). Groups RESX (n = 8) and RES (n = 6) trained 3 days/week for 12 weeks with large-muscle mass exercises (squat, deadlift, push press, bent row and mid-thigh
pull). Group RESX also performed three sets of ten repetitions of a head extension exercise 3 days/week with a load equal
to the 3 × 10 repetition maximum (RM). Group CON (n = 8) was a control group. The cross-sectional area (CSA) of nine individual muscles or muscle groups was determined by magnetic
resonance imaging (MRI) of the cervical region. The CSA data were averaged over four contiguous transaxial slices in which
all muscles of interest were visible. The 3 × 10 RM for the head extension exercise increased for RESX after training [from
17.9 (1.0) to 23.9 (1.4) kg, P < 0.05] but not for RES [from 17.6 (1.4) to 17.7 (1.9)␣kg] or CON [from 10.1 (2.2) to 10.3 (2.1) kg]. RESX showed an increase
in total neck muscle CSA after training [from 19.5 (3.0) to 22.0 (3.6) cm2, P < 0.05], but RES and CON did not [from 19.6 (2.9) to 19.7 (2.9)␣cm2 and 17.0 (2.5) to 17.0 (2.4) cm2, respectively]. This hypertrophy for RESX was due mainly to increases in CSA of 23.9 (3.2), 24.0 (5.8), and 24.9 (5.3)% for
the splenius capitis, and semispinalis capitis and cervicis muscles, respectively. The lack of generalized neck muscle hypertrophy
in RES was not due to insufficient training. For example, the CSA of their quadriceps femoris muscle group, as assessed by
MRI, increased by 7 (1)% after this short-term training (P < 0.05). The results suggest that: (1) the splenius capitis, and semispinalis capitis and cervicis muscles are mainly responsible
for head extension; (2) short-term resistance training does not provide a sufficient stimulus to evoke neck muscle hypertrophy
unless specific neck exercises are performed; and (3) the postural role of head extensors provides modest loading in bipeds.
Accepted: 15 October 1996 相似文献
3.
4.
Theodore J. Angelopoulos Robert J. Robertson F. L. Goss Allan Utter 《European journal of applied physiology and occupational physiology》1997,75(2):132-135
Eight fit men [maximum oxygen consumption (O2max) 64.6 (1.9) ml · kg−1 · min−1, aged 28.3 (1.7) years (SE in parentheses) were studied during two treadmill exercise trials to determine the effect of endogenous
opioids on insulin and glucagon immunoreactivity during intense exercise (80% O2max). A double-blind experimental design was used with subjects undertaking the two exercise trials in counterbalanced order.
Exercise trials were 20 min in duration and were conducted 7 days apart. One exercise trial was undertaken following administration
of naloxone (N; 1.2 mg; 3 ml) and the other after receiving a placebo (P; 0.9% NaCl saline; 3 ml). Prior to each experimental
trial a flexible catheter was placed into an antecubital vein and baseline blood samples were collected. Immediately after,
each subject received either a N or P bolus injection. Blood samples were also collected after 20 min of continuous exercise
(running). Glucagon was higher (P < 0.05), while insulin was lower (P < 0.05), during exercise compared with pre-exercise values in both trials. However, glucagon was higher (P < 0.05) in the P than in the N exercise trial [141.4 (8.3) ng · l−1 vs 127.2 (7.6) ng · l−1]. There were no differences in insulin during exercise between the P and N trials [50.2 (4.3) pmol · l−1 vs 43.8 (5) pmol · l−1]. These data suggest that endogenous opioids may augment the glucagon response during intense exercise.
Accepted: 15 June 1996 相似文献
5.
C. Schirlo A. Bub C. Reize A. Bührer J. Kohl E. A. Koller 《European journal of applied physiology and occupational physiology》1997,75(2):124-131
To investigate the role of fluid shifts during the short-term adjustment to acute hypobaric hypoxia (AHH), the changes in
lower limb (LV) and forearm volumes (FV) were measured using a strain-gauge plethysmograph technique in ten healthy volunteers
exposed to different altitudes (450 m, 2500 m, 3500 m, 4500 m) in a hypobaric chamber. Arterial blood pressure, heart rate,
arterial oxygen saturation (S
aO2), endtidal gases, minute ventilation and urine flow were also determined. A control experiment was performed with an analogous
protocol under normobaric normoxic conditions. The results showed mean decreases both in LV and FV of −0.52 (SD 0.39) ml · 100
ml−1 and −0.65 (SD 0.32) ml · 100 ml−1, respectively, in the hypoxia experiments [controls: LV −0.28 (SD 0.37), FV −0.41 (SD 0.47) ml · 100 ml−1]. Descent to normoxia resulted in further small but not significant decreases in mean LV [−0.02 (SD 0.11) ml · 100 ml−1], whereas mean FV tended to increase slightly [ + 0.02 (SD 0.14) ml · 100 ml−1]; in the control experiments mean LV and FV decreased continuously during the corresponding times [−0.19 (SD 0.31), −0.18
(SD 0.10) ml · 100 ml−1, respectively]. During the whole AHH, mean urine flow increased significantly from 0.84 (SD 0.41) ml · min−1 to 3.29 (SD 1.43) ml · min−1 in contrast to the control conditions. We concluded that peripheral fluid volume shifts form a part of the hypoxia-induced
acute cardiovascular changes at high altitude. In contrast to the often reported formation of peripheral oedema after prolonged
exposure to hypobaric hypoxia, the results provided no evidence for the development of peripheral oedema during acute induction
to high altitude. However, the marked increase in interindividual variance in S
aO2 and urine flow points to the appearance of the first differences in the short-term adjustment even after 2 h of acute hypobaric
hypoxia.
Accepted: 27 August 1996 相似文献
6.
A. Falkenbach Annette Sedlmeyer Uwe Unkelbach 《International journal of biometeorology》1998,41(3):128-131
In humans, the serum concentration of parathyroid hormone (PTH) is higher in winter than in summer. The increase of PTH can
be suppressed by oral vitamin D supplements, which is considered beneficial to those with osteoporosis. The present study
investigates whether this effect can also be achieved by serial ultraviolet (UV) irradiation of the skin. In total, 34 women
suffering from postmenopausal osteoporosis were included in the open trial. In late winter, 20 patients were irradiated with
a spectrum containing UVB, eight times over a period of 4 weeks. The serum concentrations of 25-hydroxyvitamin D [25(OH)D],
1,25-dihydroxyvitamin D [1,25(OH)2D], PTH, osteocalcin, alkaline phosphatase (AP), calcium and phosphorus were measured before the first, and 2 days after the
last, dose of radiation. The data were compared to the controls (n=14, no UV exposure), who were evaluated once at the start of the study and then again 4 weeks later. After UV irradiation
the level of 25(OH)D was increased, whilst that of PTH remained unchanged. The serum level of osteocalcin decreased in the
control group, but did not change in the group of women who had been exposed to UV radiation. The present study of osteoporotic
women does not confirm previous findings in studies of healthy volunteers i.e. that PTH can be suppressed by exposure to UVB
radiation in winter. Further studies are required to specify whether there are subgroups of osteoporotic people who may benefit
from exposure to UVB radiation during winter.
Received: 31 October 1996 / Accepted: 21 October 1997 相似文献
7.
A. X. Bigard D. Merino F. Lienhard B. Serrurier C. Y. Guezennec 《European journal of applied physiology and occupational physiology》1997,75(5):380-387
The aim of this study was to quantify the degenerative and regenerative changes in rat soleus muscle resulting from 3-week
hindlimb suspension at 45° tilt (HS group, n = 8) and 4-week normal cage recovery (HS-R group, n = 7). Degenerative changes were quantified by microscope examination of muscle cross sections, and the myosin heavy chain
(MHC) composition of soleus muscles was studied by sodium dodecyl sulphate polyacrylamide gel electrophoresis. At the end
of 3-week hindlimb suspension, histological signs of muscle degenerative changes were detected in soleus muscles. There was
a significant variability in the percentage of fibres referred to as degenerating (%dg) in individual animals in the HS group
[%dg = 8.41 (SEM 0.5)%, range 4.66%–14.08%]. Moreover, %dg varied significantly along the length of the soleus muscle. The
percentage of fibres with internal nuclei was less than %dg in HS-soleus muscles [4.12 (SEM 0.3)%, range 1.24%–8.86%]. In
4-week recovery rats, the greater part of the fibres that were not referred to as normal, retained central nuclei [15.8 (SEM
2.2)%, range 6.2%–21.1%]. A significant increase in the slow isoform of MHC was recorded in the HS-R rats, compared to muscles
from age-matched rats (P < 0.01). These results would suggest that a cycle of myofibre degeneration-regeneration occurred during HS and passive recovery,
and that the increased accumulation of slow MHC observed in soleus muscles after recovery from HS could be related to the
prevalence of newly formed fibres.
Accepted: 14 October 1996 相似文献
8.
Yuko Taniguchi 《European journal of applied physiology and occupational physiology》1997,75(2):144-150
Maximal voluntary strength of simultaneous bilateral exertion has been shown to be small compared to the sum of the unilateral
exertions. Three experiments were conducted to determine the effects of bilateral and unilateral resistance training on this
bilateral deficit and to compare these in hands, arms, and legs. In each experiment, the subjects were divided into three
groups: unilateral training group, bilateral training group, and control group. The subjects of the training group performed
maximal isometric handgrip training in experiment I, and maximal isokinetic arm and leg extension training in experiments
II and III. In each experiment, the subjects of the training group continued one of these resistance training exercises three
times a week, for 6 weeks. The increase in handgrip strength of the bilateral training group produced in the bilateral condition
[5.1 (SEM 2.4)%, after 3 weeks, 6.4 (SEM 2.3) %, after 6 weeks] was significantly greater compared with the control group
[−1.1 (SEM 1.0) %, after 3 weeks, −1.5 (SEM 1.1) %, after 6 weeks. The increase in leg extension power of the bilateral training
group produced in the bilateral condition [16.1 (SEM 9.6) %, after 3 weeks, 24.1 (SEM 7.4) %, after 6 weeks] was significantly
greater compared with the unilateral training group [−5.0 (SEM 3.4) %, after 3 weeks, −3.4 (SEM 4.2) %, after 6 weeks] and
the control group [−4.3 (SEM 2.5) %, after 3 weeks, 1.5 (SEM 5.5) %, after 6 weeks]. The increase in handgrip strength of
the unilateral training group produced in the unilateral condition [7.3 (SEM 1.7) %, after 3 weeks] was significantly greater
compared with the control group [−0.9 (SEM 1.8) %, after 3 weeks]. The increase in arm extension power of the unilateral training
group produced in the unilateral condition [7.2 (SEM 1.8) %, after 6 weeks] was significantly greater compared with the bilateral
training group [−3.0 (SEM 2.3) %, after 6 weeks] and the control group [−2.1 (SEM 2.6) %, after 6 weeks]. Bilateral indexes
(BI) were shifted in a positive direction by bilateral training and tended to shift in a negative direction by unilateral
training. With regard to the magnitude of change in BI, there were no significant differences among handgrip, arm extension,
and leg extension training. It is suggested that there is lateral specificity in resistance training and that there is no
difference among body parts in the modification of bilateral deficit by lateral training.
Accepted: 27 August 1996 相似文献
9.
We used a genetic assay to monitor the behavior of sister chromatids during the cell cycle. We show that the ability to induce
sister chromatid exchanges (SCE) with ionizing radiation is maximal in budded cells with undivided nuclei and then decreases
prior to nuclear division. SCE can be induced in cells arrested in G2 using either nocodazole or cdc mutants. These data show that sister chromatids have two different states prior to nuclear division. We suggest that the
sister chromatids of cir. III, a circular derivative of chromosome III, separate (anaphase A) prior to spindle elongation
(anaphase B). Other interpretations are also discussed. SCE can be induced in cdc mutants that arrest in G2 and in nocodazole-treated cells, suggesting that mitotic checkpoints arrest cells prior to sister
chromatid separation.
Received: 3 July 1996 / Accepted: 4 October 1996 相似文献
10.
Fumihiko Sugino Tokuo Ogawa Satoshi Umemura Satoru Suzuki Yasuhiro Kawamura 《European journal of applied physiology and occupational physiology》1997,75(3):252-255
The influence of the increased cerebral blood flow (CBF) induced by acetazolamide on tympanic temperature (T
ty) was examined in three healthy male volunteers and in five patients with subacute subarachnoid haemorrhage (SAH). The CBF
was estimated by means of stable xenon-enhanced computed tomography before and after the administration of acetazolamide.
The T
ty was recorded continuously in both ears using thermistor thermometers. In all subjects, CBF increased ranging from 11% to
108% after acetazolamide administration. In all the healthy subjects and in two patients with mild SAH, T
ty was higher than the oesophageal temperature (T
oes) and T
ty decreased bilaterally, ranging from 0.07 to 0.35°C as CBF increased. Three patients with severe SAH were febrile, their T
oes exceeding T
ty, and their T
ty rose by 0.30 to 0.53°C with increased CBF. These observations suggest that T
ty follows brain temperature which changes with an increase in CBF in euthermic subjects as well as in febrile subjects.
Accepted: 3 September 1996 相似文献
11.
Tatiana Aminoff Juhani Smolander O. Korhonen Veikko Louhevaara 《European journal of applied physiology and occupational physiology》1997,75(4):363-368
Ten young (aged 23–30 years) and nine older (aged 54–59 years) healthy men with a similar size of limb muscle mass performed
arm crank and leg cycle exercise for 30 min at relative exercise intensities of 50% and 75% of maximal oxygen uptake for the
corresponding muscle group. In the tests, heart rate, blood pressure, gas exchange variables, rating of perceived exertion
and blood lactate concentration were measured. The limb muscle mass was determined by anthropometric measurements. At the
75% target exercise level, four of the older men and two of the young men could not complete the arm-cranking test, and one
of the older men and two of the young men could not complete the leg-cycle test. During arm-cranking the absolute exercise
intensity was similar for the young and older men because of similar maximal values during arm-cranking. But during leg-cycling
the absolute excercise intensity was higher for the young men than for the older men due to the difference in corresponding
maximal values. During arm-cranking there were no significant differences in the physiological responses between the age groups
except that a higher ventilatory response was noted among the older compared to the young men. During leg-cycling the heart
rate values were higher among the young compared to the older men. But, when the heart rate values were expressed as a percentage
of maximal heart rate in the corresponding maximal tests, no significant differences between the age groups were found. The
results indicated that 30-min of arm or leg exercise at the same relative submaximal excercise intensity produces a similar
degree of physiological strain in healthy older compared to young men. During arm-cranking, the young and the older men exercised
at the same external intensity, indicating a similar ability to perform prolonged excercise using smaller muscle groups expressed
both in absolute and relative terms.
Accepted: 7 October 1996 相似文献
12.
Trained versus untrained men: different immediate post-exercise responses of pituitary adrenal axis 总被引:4,自引:0,他引:4
M. Duclos J.-B. Corcuff M. Rashedi V. Fougère G. Manier 《European journal of applied physiology and occupational physiology》1997,75(4):343-350
The hypothalamo-pituitary-adrenal axis is involved throughout the exercise-recovery cycle. Nevertheless, differences in hormone
responses during early recovery between sedentary and endurance trained subjects are not well known. The aim of this preliminary
study was to monitor plasma cortisol and adrenocorticotropic hormone (ACTH) concentrations both during and after the end of
running exercise performed by four endurance trained adults (marathon men) compared to four sedentary subjects. Two parameters,
i.e. intensity and duration, were changed on 4 consecutive days. The 1st day (D0) was spent in the laboratory: all blood samples were obtained at rest to determine diurnal variations of each hormone. On
the following days (D1–D4) the subjects exercised: D1 and D2 brief (20 min), light (50% maximal heart rate HRmax, D1) or strenuous (80% HRmax, D2), D3 and D4 prolonged (120 min), light (D3) or strenuous (D4). In both groups, neither brief (D1, D2) nor prolonged light exercise (D3) induced any significant variation in plasma ACTH or cortisol concentrations. Plasma ACTH and cortisol concentrations increased
only if the exercise was intense and prolonged (D4). The training factor did not modify the intensity or duration thresholds for the activation of the pituitary-adrenocortical
response to exercise in the conditions of our experiment. However, during immediate recovery from the four exercise regimens,
the plasma ACTH concentrations of the marathon men were constantly above the values of the sedentary subjects, although plasma
cortisol concentration remained similar in both groups. As an indirect means of evaluating the relationships between ACTH
and cortisol we compared the areas under the cortisol and ACTH curves (AUC) from 0.5 to 3.5h during recovery from D1 to D4 compared to D0 at the same time. Cortisol AUC were similar in the sedentary subjects and marathon men although the ACTH AUC were different
in the sedentary subjects and marathon men, suggesting a change in the pituitary-adrenal relationship at some yet indeterminate
level. During the immediate recovery from exercise whatever its intensity, the magnitude of the ACTH response was increased
in the trained subjects but with a reduced effect upon its target, the adrenal glands. This phenomenon has not been described
in the literature. Two non-exclusive phenomena may be involved, i.e. a decreased adrenal sensitivity to ACTH stimulation,
and/or a decreased hypothalamo-pituitary axis sensitivity to cortisol negative feedback.
Accepted: 6 August 1996 相似文献
13.
Effects of ultraviolet radiation on early larval stages of the Alpine newt, Triturus alpestris, under natural and laboratory conditions 总被引:3,自引:0,他引:3
Although Alpine newts (Triturus alpestris) are found at altitudes up to 2500 m, their larvae proved to be extremely sensitive to UV radiation when exposed in clear
tapwater to natural sunlight or to comparable artificial UV-B radiation in the laboratory. The experiments revealed severe
skin damages (lysis of epithelial cells) and mortality after a few days of exposure. In their natural habitats above the timberline,
however, the larvae are protected by the high concentration of dissolved organic carbon in the water leading to an almost
complete absorption of UV radiation within the first few centimeters of the water layer. Furthermore, when exposed to UV radiation
larvae show erratic swimming activities that may carry them into protected areas. Only in very shallow natural habitats did
we detect sublethal UV-like histological effects. Shallow high mountain ponds with clear water normally lack newt populations,
probably as a consequence of both low temperature and the effects of UV radiation.
Received: 4 October 1996 / Accepted: 7 February 1997 相似文献
14.
T. J. Vasankari U. M. Kujala H. Rusko S. Sarna M. Ahotupa 《European journal of applied physiology and occupational physiology》1997,75(5):396-399
We investigated the effect of training and racing at moderate altitude (MA) on oxidative stress by assessment of serum diene
conjugation (DC) and serum antioxidant potential (TRAP). Nine male top level skiers were studied during a national race (20–30
km) at sea level (SL). Thereafter, the athletes trained for 2 weeks at MA, after which they participated in a 20–30 km race
at MA. Venous blood samples were taken before and after the race. The DC, indicating early events of lipid peroxi dation,
did not change during the race at SL (16 850 vs 15 900 ΔAbsorbance · l−1) or at MA (19 870 vs. 20 630 ΔAbs · l−1). At MA serum DC was higher than at SL both before (25%) and after (30%) the race, the postrace difference being statistically
significant (P < 0.05). The TRAP increased during the race at MA (from 1387 to 1943 μmol · 1−1, P = 0.016), but not at SL (1713 vs 1582 μmol · l−1). These observations would suggest that the level of oxidative stress might be greater during living, training and racing
at MA (higher DC levels). Increased TRAP during the race at MA may indicate that the physiological adaptation to extreme acute
oxidative stress was altered. The physiological significance of this observation remains to be investigated.
Accepted: 18 October 1996 相似文献
15.
Mapping QTLs for submergence tolerance in rice by AFLP analysis and selective genotyping 总被引:11,自引:0,他引:11
S. Nandi P. K. Subudhi D. Senadhira N. L. Manigbas S. Sen-Mandi N. Huang 《Molecular & general genetics : MGG》1997,255(1):1-8
By combining the amplified fragment length polymorphism (AFLP) technique with selective genotyping, we constructed a linkage
map for rice and assigned each linkage group to a corresponding chromosome. The AFLP map, consisting of 202 AFLP markers,
was generated from 74 recombinant inbred lines (RIL) which were selected from both extremes of the population (250 lines)
with respect to the response to complete submergence. Map length was 1756 cM, with an average interval size of 8.5 cM. To
assign linkage groups to chromosomes, we used 50 previously mapped AFLP markers as anchor markers distributed over the 12
chromosomes. Other AFLP markers were then assigned to specific chromosomes based on their linkage to anchor markers. This
AFLP map is equivalent to the RFLP/AFLP map constructed previously as the anchors were in the same order in both maps. Furthermore,
tests with two restriction fragment length polymorphism (RFLP) markers and two sequence-tagged site (STS) markers showed that
they mapped in the expected positions. Using this AFLP map, a major gene for submergence tolerance was localized on chromosome
9. Quantitative trait loci (QTL) associated with submergence tolerance were detected on chromosomes 6, 7, 11, and 12. We conclude
that the combination of AFLP mapping and selective genotyping provides a much faster and easier approach to QTL identification
than the use of RFLP markers.
Received: 20 December 1996 / Accepted: 21 January 1997 相似文献
16.
H. P. Zippel P. W. Sorensen A. Hansen 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1996,180(1):39-52
1. To determine whether microvillous olfactory receptor cells mediate responses to pheromonal cues, the olfactory nerves
of mature male goldfish were axotomized and both the olfactory and behavioral sensitivity of these animals to olfactory stimuli
investigated after which the histological condition of their olfactory epithelia was determined. 2. Behavioral responsiveness
to food odor returned within 2 weeks but responsiveness to sexually-active females (pheromones) took 4–10 weeks to return.
3. Electro-olfactogram recordings from the olfactory epithelium of axotomized fish found that olfactory responsiveness to
amino acids and pheromones changed little during the first week subsequent to axotomy. However, olfactory sensitivity decreased
rapidly during the second week. During the course of the third week, electro-olfactogram sensitivity to amino acids remained
while exposure to pheromones evoked no recordable electro-olfactogram. During week 4, sensitivity to amino acids increased
further, and weak sensitivity to some pheromones became evident. Further recovery of electro-olfactogram sensitivity to all
odorants was slow and erratic over the next 6 months, particularly to the pheromones. 4. Histological examination of the olfactory
epithelia of axotomized fish demonstrated that while ciliated receptor cells were present within 2 weeks, microvillous receptor
cells took approximately 4 weeks to regenerate. 5. Together these data suggest that microvillous receptor cells mediate responsiveness
to pheromones in this species.
Accepted: 22 August 1996 相似文献
17.
A. D. Taylor R. Bronks P. Smith B. Humphries 《European journal of applied physiology and occupational physiology》1997,75(2):151-159
Integrated electromyography (iEMG) of the m. vastus lateralis was analysed during cycle ergometry in male subjects (n = 8). Two work trials were conducted, one under normoxia (N), the other under environmental normobaric hypoxia (EH in which
the oxygen fraction in inspired gas = 0.116), each trial lasting 10 min. The absolute power output (180 W) was the same for
both trials and was equivalent to 77 (4)% of maximum heart rate in trial N. Maximal voluntary isometric contractions were
performed after each trial to assess changes in force, muscle fibre conduction velocity (MFCV), electromechanical delay (EMD),
median frequency of EMG (MF) and maximal iEMG (iEMGmax). Biopy samples of muscle were obtained from the m. vastus medialis before testing. Myosin heavy chain (MHC) differences
were determined through sodium dodecyl-polyacrylamide gel electrophoresis followed by densitometric analysis. No differences
in submaximal iEMG were observed between EH and N trials during the first minute of work. At the end of both work trials iEMG
was significantly elevated compared with starting values, however the iEMG recorded in EH exceeded N values by 15%. At the
end of the EH trials the following were observed: a decrease in isometric force, MFCV and MF with an increase in EMD and the
iEMGmax/force ratio. The iEMGmax was unchanged. No differences in any of these variables were observed after the N trial. Mean (SD) lactate concentrations
following EH and N trials were 9.2 (4.4) mmol · 1−1 and 3.5 (1.1) mmol · 1−1, respectively. Results indicate that an increased motor unit recruitment and rate coding was needed in EH to maintain the
required power output. The increased motor unit recruitment and rate coding were associated with myoelectric evidence of “peripheral”
muscle fatigue. Subjects with higher compositions of type II MHC accumulated more lactate and displayed greater reductions
in MF and MFCV during fatigue.
Accepted: 16 June 1996 相似文献
18.
目的:探讨蒙药乌力吉-18对大鼠下丘脑-垂体-卵巢轴相关激素及受体的影响。方法:选取40只健康雌性未孕SD大鼠,随机分为空白组、对照组、乌力吉-18高、低2个剂量组,每组10只。空白组灌胃等体积蒸馏水,对照组灌胃逍遥丸,高、低剂量组分别灌胃2.0 g·kg-1·d-1、1.0 g·kg-1·d-1乌力吉-18,连续给药31学艺术d。采用酶联免疫吸附法测定血清促性腺激素释放激素(GnRH)、促卵泡生成素(FSH)、黄体生成素(LH)、雌二醇(E2)及孕酮(PROG)的含量;免疫组化法检测下丘脑组织促性腺激素释放激素(GnRH)、垂体组织促性腺激素释放激素受体(GnRHR)的表达;以蛋白免疫印迹技术检测卵巢组织促卵泡生成素受体(FSHR)、黄体生成素受体(LHR)蛋白表达量。以实时荧光定量PCR检测卵巢组织中FSHR、LHR基因表达量。结果:与空白组比较,乌力吉-18低剂量组可明显升高血清LH含量(P<0.05),上调下丘脑组织GnRH、垂体组织GnRHR表达及卵巢组织FSHR、LHR蛋白表达(P<0.05);乌力吉-18高剂量组可显著升高血清FSH、LH、E2含量(P<0.05),上调下丘脑组织GnRH表达及卵巢组织FSHR表达量(P<0.05),并可显著升高卵巢组织中FSHR、LHR基因表达量(P<0.05);对照组可明显升高血清E2含量(P<0.05)。结论:蒙药乌力吉-18可明显升高血清FSH、LH及E2的含量,促进下丘脑组织GnRH、垂体组织GnRHR及卵巢组织中FSHR、LHR的表达,表明乌力吉-18能够对下丘脑-垂体-卵巢轴相关激素及受体表达产生影响。 相似文献
19.
Daniel W. Schneider 《Oecologia》1997,110(4):567-575
Food web statistics showed a complex relationship with measures of habitat variability in temporary ponds. Connectance was
highest in short-duration, highly variable habitats, and lowest in habitats of intermediate duration and variability. The
number of links and links/taxon increased with increasing duration. Much of the variation in the food web statistics could
be explained by a strong linear relationship between number of taxa and number of links/taxon and a quadratic relationship
of taxa number with the number of links. However, after accounting for this variation, there remained a relationship of duration
with links and links/taxon. The relationship between the food web statistics and duration corresponded to experimental evaluations
of predation in these habitats that showed an increasing importance of predation in long-duration habitats. The food web statistics,
however, missed threshold effects in the relationship between predation and habitat duration. Differences in food web statistics
before and after a regional drought could be explained by a decrease in taxa number after the drought. Connectance was the
most robust statistic in relation to taxa number, but was also the least sensitive to changes in habitat characteristics.
Received: 11 March 1996 / Accepted: 8 January 1997 相似文献
20.
Christian-Serge Degoute M.-P. Preckel Christian Dubreuil Vincent Banssillon Roland Duclaux 《European journal of applied physiology and occupational physiology》1997,75(4):326-332
The purpose of this work was to show that regulation of the blood flow to the cochlea by the sympathetic nervous system occurs
in humans at the level of the cochlear microcirculation during increases in blood pressure and that its involvement depends
on the pressure level. Eight anaesthetized patients undergoing tympanoplasty for hearing disease took part in a pharmacological
protocol of stimulation and inhibition of the autonomic nervous system (ANS) to provide variations in systolic blood pressure
(BPS) and cochlear blood flow (CBF). The CBF was measured by laser-Doppler flowmetry. Changes in autonomic nerve activity were
brought about by changes in baroreceptor activity (BR) initiated by the injection of an α adrenergic agent before and after
sympathetic and parasympathetic blockade. The CBF variations (δCBF) were plotted against BPS increases at each stage of the ANS inhibition. The BR diminished significantly after α blockade, after α and β blockade,
and after α and β blockade and atropine, by 50% (P < 0.01), 29% (P < 0.05), and 95% (P < 0.001) respectively. The BPS increased significantly (P < 0.01) by 36 (SD 9)%, 47 (SD 1)%, and 67 (SD 16)% respectively. The CBF response to an increase in BPS exhibited two opposing variations in the patients: CBF decreased significantly in one group, and increased significantly
in the other group. In both groups, δCBF decrease and δCBF increase, respectively, were significant after ANS blockade; even
so the decrease and increase, respectively, levelled off at BPS around 160 mmHg before ANS blockade. For BPS below 160 mmHg, correlations between δCBF and BPS were significant before inhibition and after inhibition of ANS. For BPS above 160 mmHg, BPS and δCBF were not correlated before inhibition of ANS, and were significantly correlated after inhibition of ANS. For BPS below 160 mmHg, CBF response to the BPS increase was the same before and after ANS blockade, i.e. ANS control did not predominate; even so, for BPS above 160 mmHg, the CBF response to BPS increase was different before and after ANS blockade: CBF varied significantly after ANS blockade as it varied for BPS below 160 mmHg, while it remained constant before ANS blockade that elicited ANS control of CBF. In conclusion, sympathetic
nerve regulation via its vasomotor tone at the level of cochlear microcirculation occurred markedly when the blood pressure
was above 160 mmHg; the autonomic nervous system would appear to control the cochlear blood flow against large variations
in blood flow in response to hypertensive phenomena.
Accepted: 7 October 1996 相似文献