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1.
Anisuzzaman Khyrul Islam M Abdul Alim M Miyoshi T Hatta T Yamaji K Matsumoto Y Fujisaki K Tsuji N 《Biochemical and biophysical research communications》2011,(4):599-604
Thrombo-occlusive diseases are major causes of morbidity and mortality, and tissue-type plasminogen activator (t-PA) is recommended for the treatment of the maladies. However, both t-PA and u-PA are rapidly inactivated by plasminogen activator inhibitor-1 (PAI-1). Here, we show that longistatin, a novel plasminogen activator isolated from the ixodid tick, Haemaphysalis longicornis is resistant to PAI-1. Longistatin was relatively less susceptible to the inhibitory effect of SDS-treated platelet lysate than physiologic PAs. Platelet lysate inhibited t-PA and tcu-PA with the IC50 of 7.7 and 9.1 μg/ml, respectively, whereas for longistatin inhibition IC50 was 20.1 μg/ml (p < 0.01). Similarly, activated PAI-1 (20 nM) inhibited only 21.47% activity of longistatin but almost completely inhibited t-PA (99.17%) and tcu-PA (96.84%). Interestingly, longistatin retained 76.73% initial activity even after 3 h of incubation with 20 nM of PAI-1. IC50 of PAI-1 during longistatin inhibition was 88.3 nM while it was 3.9 and 3.2 nM in t-PA and tcu-PA inhibition, respectively. Longistatin completely hydrolyzed fibrin clot by activating plasminogen efficiently in the presence of 20 nM of PAI-1. Importantly, unlike t-PA, longistatin did not form complex with PAI-1. Collectively, our results suggest that longistatin is resistant to PAI-1 and maybe an interesting tool for the development of a PAI-1 resistant effective thrombolytic agent. 相似文献
2.
McInnis MD Newhouse IJ von Duvillard SP Thayer R 《European journal of applied physiology and occupational physiology》1998,79(1):99-105
The purpose of this study were: (1) to establish the prevalence of exercise-induced hematuria in a group of otherwise healthy
male runners (n = 70), and (2) to investigate the role of exercise intensity in those runners who exhibited exercise-related hematuria (n = 10) by evaluating the effect of running and cycling at high and low intensities. The identified and recruited subjects
participated in four different exercise protocols: (1) a 60-min treadmill run (RUN) at 90% of anaerobic threshold (Thae), (2) a 60-min leg cycle ergometer ride (BIKE) at 90% of Thae, (3) a 3×400-m sprint (SPRINT), each followed by 4 min of rest or light walking, and (4) 3×60-Wingate leg cycle ergometry
tests, each followed by 4 min of rest or light cycling. The study employed a 3×4 (time by protocol) within-subjects design
and dependent variables were measured before exercise, 4 min after, and 1 h after exercise, and included measurements of hematuria,
proteinuria, urinary pH, serum haptoglobin concentration, serum creatine phosphokinase activity, plasma lactate concentration,
and hemoglobin. The 400-m sprint at maximal effort significantly increased both hematuria and proteinuria (P < 0.01). Post-exercise hematuria for the SPRINT protocol was significantly different than that for the BIKE (P < 0.01) and RUN (P < 0.01) protocols. Due to the significant increase in hematuria and proteinuria following the SPRINT protocol, it was concluded
that exercise-related changes in renal function were associated with weight-bearing exercise intensity rather than non-weight-bearing
exercise duration.
Accepted: 30 April 1998 相似文献
3.
Asselbergs FW Williams SM Hebert PR Coffey CS Hillege HL Snieder H Navis G Vaughan DE van Gilst WH Moore JH 《Human genetics》2007,122(3-4):275-281
Thrombosis is a key factor in the pathophysiology of cardiovascular disease. Important biochemical constituents of the fibrinolytic
system, affecting thrombosis, include tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1).
Both t-PA and PAI-1 are determined by multiple genetic and environmental factors. We aimed to investigate whether the effects
of polymorphism in genes from the renin–angiotensin, bradykinin, and fibrinolytic systems on t-PA or PAI-1 levels are dependent
on environmental factors in a large population-based sample from the PREVEND study in Groningen, The Netherlands (n = 2,527). We found strong evidence (P ≤ 0.02) for interaction effects of polymorphisms from the bradykinin receptor (BDKRB2) gene and alcohol consumption on t-PA in females and males and on PAI-1 in males. Only suggestive evidence (P ≤ 0.10) was present for an interaction effect of the BDKRB2 gene and alcohol consumption on PAI-1 levels in females. Another consistent finding was evidence for an interaction between
bradykinin receptor (BDKRB2) gene polymorphisms and body size as measured by body mass index and/or waist–hip-ratio. For each gender and for both t-PA
and PAI-1 there was at least one BDKRB2–body size combination that exhibited suggestive (P ≤ 0.10), significant (P ≤ 0.04) and/or strong evidence (P ≤ 0.02) for interaction. In conclusion, the genetic architecture of t-PA and PAI-1 is dependent on the environmental context
such as body size and alcohol use. The present study emphasizes the importance of including environmental factors in genetic
analyses to fully comprehend the genetic architecture of a specific trait.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
4.
《Chronobiology international》2013,30(5):352-360
We report a comparison of fibrinolytic variables between 10 Caucasians on a predominantly European diet and 10 Greenland Eskimos on a traditional Inuit diet containing a substantial amount of fish and sea animals. We studied the diurnal variation in tissue type plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI) antigens and activities during a 24-h period. Blood samples were taken every 4 h. The variations of the sinusoidal curves were evaluated by the Friedman χ2 test. t-PA and PAI-1 antigen in plasma fluctuated significantly during the 24 h (Eskimos p < 0.000007 and p < 0.0007; Caucasians p < 0.00003 and p < 0.02), with a peak in the early morning and a nadir in the afternoon. This also held true for PA1 activity (Eskimos p < 0.0008; Caucasians p < O.Ol), whereas t-PA activity showed an inverse but still significant pattern (Eskimos p < 0.006; Caucasians p < 0.0008). Amplitudes, areas underneath, and overall medians of the sinusoidal curves did not deviate between the two groups with respect to t-PA and PAL In contrast to the significant variation of t-PA and PAI, the plasma concentrations of fibrin degradation products (D-Dimer), a measure of effective fibrinolysis, remained constant during the 24 h, and the absolute differences between groups did not reach statistical significance. These findings suggest that circadian variation of fibrinolytic activators and inhibitors is a basic biologic phenomenon, which is not affected by life-style, dietary habits, or ethnic differences. Furthermore, the lack of diurnal variation in D-Dimer raises the question of whether there is a causal relationship between low morning activities of t-PA and the frequent onset of myocardial infarction at that time of day, as suggested by several authors. 相似文献
5.
J. A. De Paz J. Lasierra J. G. Villa E. Viladés M. A. Martín-Nu?o J. González-Gallego 《European journal of applied physiology and occupational physiology》1992,65(5):388-393
The effects of physical conditioning on plasma fibrinolytic activity were studied in two groups of subjects. Volunteers not engaged in any sport were compared with individuals having been subjected to aerobic conditioning (middle-distance runners, defined as men running more than 80 km per week). Plasma concentrations of the different components of the fibrinolytic system were evaluated before and immediately after a maximal effort treadmill protocol. Comparison of the resting parameters revealed that under basal conditions for plasma concentrations of plasminogen, fibrinogen, alpha 2-antiplasmin, protein C and protein S there were no differences between the two groups. Concentrations of the fibrin degradation products (FbDP) and fibrinogen degradation products (FgDP) were significantly higher in the runners than in the control group, indicating an increased fibrinolytic potential that seemed to be a consequence of the reduced formation of tissue plasminogen activator-plasminogen activator inhibitor (t-PA-PAI) complexes. Acute maximal exercise resulted in pronounced fibrinolysis, evidenced by the elevation of FbDP and FgDP concentrations, in both groups of subjects. The acceleration of the fibrinolytic activity was larger in conditioned individuals, which could be accounted for by a higher t-PA release and reduced formation of t-PA-PAI complexes when compared to the untrained subjects. 相似文献
6.
mRNA levels for urokinase type plasminogen activator (uPA), tissue type plasminogen activator (tPA), plasminogen activator
inhibitor-1 (PAI-1) and plasminogen activator inhibitor-2 (PAI-2) were examined in human diploid (neonatal foreskin) fibroblasts
grown in 200-ml microcarrier suspension culture. Four different substrates were used. These included gelatin-coated polystyrene
plastic, DEAE-dextran, glass-coated polystyrene plastic and uncoated polystyrene plastic. Our previous studies have shown
that culture fluids from diploid fibroblasts grown on DEAE-dextran contained higher levels of plasminogen-dependent fibrinolytic
activity than culture fluids from the same cells grown on other substrates. The increased plasminogen activator activity was
due largely to elevated amounts of tPA (In Vitro Cell. Develop. Biol. 22: 575–582, 1986). The present study shows that there
is a corresponding elevation of tPA mRNA in diploid fibroblasts cultured on DEAE-dextran relative to the other substrates.
There does not appear to be any difference in uPA mRNA or in mRNA for PAI-1 or PAI-2 produced by the same cells on the four
substrates. These data suggest that the influence of the substrate on plasminogen activator production is mediated at the
genetic level. 相似文献
7.
Fibrinolytic components in nasal mucosa and nasal secretion 总被引:1,自引:1,他引:0
Toyotoshi Yasuda Y. Sakata Seiji Madoiwa Jun Mimuro Michio Matsuda Ken Kitamura 《Histochemistry and cell biology》1998,110(5):449-455
We evaluated a possible role for fibrinolytic components in nasal secretion by tissue localization with immunohistochemical
techniques and by measuring their antigen concentrations in nasal discharge by means of ELISA and fibrin autography. Nasal
mucosa was obtained surgically from the inferior turbinate. Urokinase-type plasminogen activator (u-PA) specific staining
was observed in pseudostratified ciliated epithelium and was predominant in mucous cells of the seromucinous gland, while
serous cells were almost devoid of stain. The pattern of staining of plasminogen activator inhibitor-2 was similar to that
of u-PA. In contrast, plasminogen activator inhibitor-1(PAI-1) immunoreactive material was localized exclusively in serous
cells of seromucinous glands. Positive staining for tissue-type plasminogen activator (t-PA) was observed in endothelial cells
and basal cells, which differentiate into either ciliated or goblet cells. Nasal secretions were partially fractionated by
immunospecific antibody-immobilized Sepharose. Subsequent fibrin autography patterns indicated the presence of u-PA, PAI-1,
and t-PA. After methacholine provocation, the level of t-PA increased transiently but decreased rapidly with subsequent challenges.
These differential stainings of fibrinolytic components and the existence of PAs and PAI-1 in the nasal discharge suggest
that the fibrinolytic system may play a role in the movement and fluidity of nasal secretion.
Accepted: 25 May 1998 相似文献
8.
Variations of components of the plasminogen activation system with the cell cycle in benign prostate tissue and prostate cancer. 总被引:4,自引:0,他引:4
E Plas V A Carroll R Jilch R Simak J Mihaly S Melchior J W Thüroff B R Binder H Pflüger 《Cytometry》2001,46(3):184-189
Background: Components of the fibrinolytic system are involved in tumor cell invasion and metastasis. Previous investigations suggested a cell cycle-dependent expression of urokinase-type plasminogen activator (u-PA) in epithelial cells. In order to determine a correlation of cell cycle phases with the fibrinolytic system, we investigated the expression of u-PA, tissue-type plasminogen activator (t-PA), and plasminogen activator inhibitor type 1 (PAI-1) in normal and tumor-containing prostate extracts and analyzed a possible relationship with flow cytometry-determined proliferative activity of the samples. Cell cycle phases were correlated with fibrinolytic parameters in prostate tissue. Methods: Samples were obtained from patients undergoing radical prostatectomy for prostate cancer and separated into two portions for DNA analysis and the detection of u-PA, t-PA, and PAI-1. Flow cytometric analysis was performed according to the Vindelov technique. The concentrations of u-PA, t-PA, and PAI-1 were determined from tissue extracts after homogenization by an enzyme-linked immunosorbent assay (ELISA) technique. Results: Correlations of u-PA and t-PA expression with the frequency of G0/G1, S, G2M, S-phase fraction (SPF), and proliferation index (PI) for normal prostate and prostate cancer revealed no significant correlation. The only significant finding was observed in normal tissue revealing a positive correlation between PAI-1 expression and G0/G1 and a negative correlation with S-phase, SPF, and PI. No dependence of PAI-1 expression on different cell phases was found in prostate cancer. Furthermore, no significant correlation of u-PA, t-PA, and PAI-1 with cell cycles in organ-confined ( or = pT3a) tumors was found. No significant correlation in prostate cancer of components of the fibrinolytic system differentiated according to tumor grade or perineural tumor infiltration and cell cycle analysis was found. Only in highly differentiated G1 (Gleason 2-4) cancer, u-PA had a significant positive correlation with G2M-phase. Conclusion: Absence of a correlation between levels of components of the fibrinolytic system and cell cycle phases suggests that the reported association between increases of some of these components and aggressive biological behavior of prostate cancer is secondary to non-cell cycle-related mechanisms. 相似文献
9.
《Chronobiology international》2013,30(5):336-351
Approximately 35 years ago, it was discovered that spontaneous fibrinolytic activity in blood showed a sinusoidal variation with a period of 24 h; it increased severalfold during the day, reaching a peak at 6:OO p.m. and then dropped to trough levels at 3:00–4:00 a.m. The range of the fluctuation and the 24-h mean levels were highly reproducible within an individual; moreover, the timing of the oscillation was remarkably consistent among individuals, with a fixed phase relationship to external clock time. The biorhythm could not be accounted for simply by variations in physical activity, body posture, or sleepfwake schedule. Gender, ethnic origin, meals, or resting levels of blood fibrinolytic activity also did not influence the basic features of the rhythm. Older subjects, compared to younger ones, showed a blunted diurnal increase in fibrinolytic activity in blood. Recent studies have established that, of the known components of the fibrinolytic system, only tissue-type plasminogen activator (tPA) and its fast-acting inhibitor, plasminogen activator inhibitor- 1 (PAL l), show a marked circadian variation in plasma. In contrast, levels of plasminogen, α2-antiplasmin, urinarytype plasminogen activator, and a reversible tPA inhibitor vary little or none during the 24 h. Quenching antibodies to tPA have shown that the circadian rhythm of fibrinolytic activity in blood is due exclusively to changes in tPA activity. However, the 24-h fluctuation of plasma tPA activity is phase shifted in relation to the rhythm of immunoreactive tPA, but shows a precise phase inversion with respect to the 24-h variation of PAL 1 activity and antigen. Therefore, plasma tPA activity, as currently measured in vitro, is tightly and inversely related to the levels of PAL 1 throughout the 24-h cycle. The factors controlling the rhythmicity of plasma PAI-1 are not fully elucidated but probably involve a humoral mechanism; changes in endothelial function, circulating platelet release. products, corticosteroids, catecholamines, insulin, activated protein C, or hepatic clearance do not appear to be responsible. Shift workers on weekly shift rotations show a disrupted 24-h rhythm of plasma tPA and PAL 1. In acute and chronic diseases, the circadian rhythmicity of fibrinolytic activity may show a variety of alterations, affecting the 24-h mean, the amplitude, or the timing of the fluctuation. It is advisable, therefore, to define the 24-h pattern of plasma tPA and PAI- 1 in patient groups, before levels based on a single blood sampling time are compared to those of a control population. In normal conditions, the 24-h variation of plasma tPA and PAI- 1 is not associated with parallel circadian changes in effective fibrinolysis, assessed as plasma D-dimer concentrations, presumably because fibrin generation in the circulation is low. In diseases in which fibrin formation is increased, however, the physiological drop of fibrinolytic activity in the morning hours may favour thrombus development at this time of day, in agreement with the reported higher morning frequency of acute thrombotic events. 相似文献
10.
It is generally accepted that the fibrinolytic potential of tumor cells is related to their malignant phenotype. In the present study, Nigella sativa oil (NSO) was studied to evaluate its effect on the fibrinolytic potential of the fibosarcoma cell line HT1080 to elucidate whether this oil might have an antitumor activity through its modulation of the fibrinolytic potential of such cells. NSO produced a concentration-dependent inhibition of tissue-type plasminogen activator (t-PA), urokinase-type plasminogen activator (u-PA) and plasminogen activator inhibitor type 1 (PAI-1). When subconfluent HT1080 cells were conditioned with oil, a concentration (0.0-200 microg oil/ml)-dependent decrease in t-PA, u-PA and PAI-1 antigen was observed. There was also a concentration-dependent decrease (from 0.0 to 112.5 microg oil/ml) in the confluent cultures. The results showed that blackseed oil decreases the fibrinolytic potential of the human fibrosarcoma cell line (HT1080) in vitro, implying that inhibition of local tumor invasion and metastasis may be one such mechanism. 相似文献
11.
Desouza Christopher A.; Dengel Donald R.; Rogers Marc A.; Cox Kim; Macko Richard F. 《Journal of applied physiology》1997,82(6):1765-1770
DeSouza, Christopher A., Donald R. Dengel, Marc A. Rogers,Kim Cox, and Richard F. Macko. Fibrinolytic responsesto acute physical activity in older hypertensive men.J. Appl. Physiol. 82(6):1765-1770, 1997.We tested the hypothesis that the fibrinolytic response to acute physical activity is impaired in sedentary older hypertensive men, which may contribute to the risk ofexertion-triggered acute myocardial infarction in this population.Tissue-type plasminogen activator (t-PA) antigen and activity andplasminogen activator inhibitor-1 (PAI-1) antigen and activity weremeasured in 12 hypertensive (69 ± 1 yr) and 11 normotensive (64 ± 1 yr) men before and after an acute bout of submaximal exercise.Contrary to our hypothesis, there were no differences between the twogroups in the fibrinolytic response to exercise. t-PA antigen andactivity were significantly elevated in both the hypertensive (38 and172%, respectively) and normotensive (45 and 130%, respectively)groups immediately after exercise but they returned to resting levelswithin 30 min. There was no change in PAI-1 antigen levels immediatelyafter exercise in either group; however, PAI-1 antigen wassignificantly lower at 30 and 60 min postexercise in both thehypertensive (31 and 16%, respectively) and normotensive (35 and 20%,respectively) groups. PAI-1 activity was significantly lowerimmediately after exercise in both the hypertensive (25%) andnormotensive (22%) groups and remained lower than preexercise levelsat 30 min (23 and 26%, respectively) and 60 min (16 and 12%,respectively) postexercise in both groups. The results of this studydemonstrate that the fibrinolytic response to an acute bout of moderatephysical activity is not impaired in sedentary older hypertensive men. 相似文献
12.
Effect of endurance training and seasonal fluctuation on coagulation and fibrinolysis in young sedentary men 总被引:5,自引:0,他引:5
Burg P. J.M.Van Den; Hospers J. E.H.; Van Vliet M.; Mosterd W. L.; Bouma B. N.; Huisveld I. A. 《Journal of applied physiology》1997,82(2):613-620
Van den Burg, P. J. M., J. E. H. Hospers, M. Van Vliet, W. L. Mosterd, B. N. Bouma, and I. A. Huisveld. Effect of endurance training and seasonal fluctuation on coagulation and fibrinolysis inyoung sedentary men. J. Appl. Physiol.82(2): 613-620, 1997.The effect of 12 wk of submaximal trainingon hemostatic variables was studied in 20 young sedentary men (Tr) and19 nontraining matched controls (Con). After training, a morepronounced increase in factor VIII coagulant activity(P < 0.01), reflected in a decrease in activated partial thromboplastin time(P < 0.01) during maximal exercise,was seen. Both basal plasminogen activator inhibitor 1 antigen (PAI-1Ag) and activity (PAI-1 Act; P < 0.05), as well as basal and exercise-induced tissue-type plasminogenactivator antigen (t-PA Ag; P < 0.05), were decreased after training. The overall effect onfibrinolysis was reflected in an increase in the t-PA Act/t-PA Ag ratioin the Tr group. In contrast, during the same period (February-June),the Con group demonstrated an increase in basal PAI-1 Ag and PAI-1 Act(P < 0.05), together with anincrease in basal and exercise-induced t-PA Ag(P < 0.05). Both basal andexercise-induced t-PA Act were unchanged, but t-PA Act/t-PA Ag wasdecreased (P < 0.05) in the Congroup. We conclude that physical training promotes both coagulation andfibrinolytic potential during exercise and may reverse unfavorableseasonal effects on fibrinolysis. 相似文献
13.
《Journal of enzyme inhibition and medicinal chemistry》2013,28(4):265-274
AbstractWe previously reported (Shimaya et al. (1992) Enzyme, 46, 204) that a rapid and strong increase of plasminogen activator (PA) was induced during anaphylaxis, and that the main plasma fibrinolytic enzyme which increased in the anaphylaxis group was shown to be tissue-type plasminogen activator (t-PA). Anaphylaxis was induced in rabbits by giving BSA after t-AMCHA injection. 44% of those rabbits died within 3 h after BSA injection. In the dead group, the euglobulin fibrinolytic activity (EFA) could not be detected by the plasminogen-rich fibrin plate method and the t-PA activity, using the natural substrate plasminogen, did not rise significantly reaching a peak at 10–15 min. However, the EFA and t-PA activity increased significantly in the surviving group. A significant prolongation of the activated partial thromboplastin time (AFTT) and the prothrombin time (PT) was observed during anaphylaxis in both groups. These findings suggest that increased PA activity during anaphylaxis is an important defense mechanism against the rapid increase in the blood coagulation system. 相似文献
14.
S C Koh P C Wong R Yuen S E Chua B L Ng S S Ratnam 《Journal of reproduction and fertility》1992,96(2):407-413
The concentrations of tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA) and plasminogen activator inhibitor (PAI-1) have been determined in endometrial curettings obtained from 46 subfertile women during proliferative, early or late secretory phases of the menstrual cycle. t-PA activity and antigen concentrations was significantly higher (P < 0.001) in late secretory endometrium than in proliferative or early secretory endometrium. Higher concentrations of PAI-1 antigen (P < 0.05) were also noted in late secretory phase than in proliferative and early secretory endometrium. However, u-PA concentration was not significantly different and no PAI activity could be demonstrated in the menstrual phases studied. Zymography studies confirmed the presence of both t-PA and u-PA in the endometrium. Ovarian hormonal patterns may therefore influence the activity of plasminogen activators especially of t-PA in the endometrium during various phases of the menstrual cycle. 相似文献
15.
Effect of retinoic acid on the synthesis of tissue-type plasminogen activator and plasminogen activator inhibitor-1 in human endothelial cells 总被引:2,自引:0,他引:2
The synthesis of plasminogen activators and inhibitors in endothelial cells is highly regulated by hormones, drugs and growth factors. The present study evaluates the effect of retinoic acid on the synthesis of tissue-type plasminogen activator (t-PA) and of plasminogen activator inhibitor-1 (PAI-1) by cultured human umbilical vein endothelial cells (HUVEC). Retinoic acid produced a time- and concentration-dependent increase in the secretion of t-PA-related antigen but not of PAI-1 related antigen into the culture medium. A maximal sevenfold increase of t-PA antigen after 24 h was observed with 10 microM and a half-maximal increase with 0.1 microM retinoic acid. Retinoic acid induced a time-dependent increase of the t-PA mRNA, with a maximum at 8 h and returning to normal at 24 h. The protein kinase inhibitor H7 decreased the t-PA antigen induced by both retinoic acid and phorbol 12-myristate 13-acetate. These results suggest that treatment of HUVEC with retinoic acid increases t-PA production by a pathway which, at some level, involves protein kinases. Thus, retinoic acid induces t-PA synthesis in the absence of altered PAI-1 synthesis, which may enhance the fibrinolytic potential of the endothelium. 相似文献
16.
Minoru Shinohara Motoki Kouzaki Takeshi Yoshihisa Tetsuo Fukunaga 《European journal of applied physiology and occupational physiology》1997,76(4):314-319
The mechanical activity of the human quadriceps muscle during maximal incremental cycle ergometry was investigated by mechanomyography
(MMG). MMG and surface electromyography (EMG) recordings of vastus lateralis muscle activity were obtained from nine males.
Cycle ergometry was performed at 60 rev/min and work load was incremented step wise by 20 W (3.2 Nm) every minute until volitional
fatigue. The mean amplitudes of MMG (mMMG) and EMG (mEMG) during the contraction phase were calculated from the last six contractions
in each load. The duration, load and work rate of exercise at exhaustion were 13.3 (1.6) min, 44.1 (5.5) Nm, 276.7 (34.7) W,
respectively. A linear relationship between mMMG and load was evident in each subject (r = 0.868–0.995), while mEMG seemed to dissociate as the load became greater. In the grouped mean data, mMMG was linearly related
to load whether aligned to the absolute (r = 0.995) or maximal (r = 0.995) load. Involvement of the noise component was further investigated by studying passive cycling by four subjects.
Pedals were rotated passively for the first half of each stage (PAS) and the subject then pushed the pedals for the second
half (ACT). In the lighter load region, the mMMG of ACT was as small as that of PAS. However, the change in the mMMG of PAS
was very small compared with that of ACT. In conclusion, this study demonstrates a linear relationship between the mMMG of
the quadriceps muscle and work load during maximal incremental cycle ergometry. The effect of movement noise was thought to
be small and stable.
Accepted: 22 April 1997 相似文献
17.
Beh?et's disease (BD) is a chronic multisystemic inflammatory disorder characterized by recurrent oral and genital aphthous ulcers, uveitis and skin lesions. Recurrent aphthous ulcer (RAU) is the most prevalent oral mucosal disease in humans. The pathogenesis and thrombopoiesis of BD and RAU have not been fully clarified. To reveal the haemostatic dysfunctions in the patients with BD and RAU, we evaluated the levels of coagulant, anticoagulant and fibrinolytic parameters in these patients.Factor VIII clotting activity (FVIII:c), protein C antigen (PC:Ag), total protein S antigen (TPS: Ag), tissue-type plasminogen activator antigen (t-PA:Ag), plasminogen activator inhibitor-1 antigen (PAI-1:Ag) and D-dimer were detected in 24 BD, 58 RAU patients and 50 controls. Results showed that levels of PC:Ag, TPS:Ag, PAI-1:Ag and D-dimer were significantly elevated in both BD and RAU patients compared with controls (P<0.01). PAI-1:Ag was even higher in BD patients than in RAU patients (74.99±12.28 vs. 69.57±13.11, P<0.05), whereas the level of t-PA:Ag was significantly reduced in patients with BD and RAU (P<0.01). In patients with RAU, PC:Ag was lower in major aphthous ulcer (MjAU) group than in minor aphthous ulcer (MiAU) group (P<0.05). The expression of FVIII:c was significantly elevated in MiAU patients compared with controls (P<0.01), while no difference was observed between MjAU patients and controls (P>0.05). Our studies showed that there were anticoagulant and fibrinolytic disorders in BD patients, which may be responsible for diminished fibrinolysis in BD. Some haemostatic parameters may be correlated with the severity of RAU. 相似文献
18.
E L Madison E J Goldsmith M J Gething J F Sambrook R D Gerard 《The Journal of biological chemistry》1990,265(35):21423-21426
Tissue-type plasminogen activator (t-PA) catalyzes the rate-limiting step in the fibrinolytic cascade: conversion of plasminogen to plasmin. Plasma contains several inhibitors of t-PA that limit its activity and prevent systemic activation of plasminogen. The most important of these is endothelial cell plasminogen activator inhibitor (PAI-1), a member of the serine protease inhibitor (serpin) gene family. We have previously demonstrated that mutation of arginine 304 of t-PA to a glutamic acid residue drastically reduces the rate of interaction between the enzyme and its suicide substrate, PAI-1, without affecting the reactivity of the enzyme toward its normal substrate, plasminogen (Madison, E. L., Goldsmith, E. J., Gerard, R.D., Gething, M.J., and Sambrook, J.F. (1989) Nature 339, 721-724). We report here the use of protein modeling to design a compensatory mutation in PAI-1 (glutamic acid 350 to arginine) and create a molecule that rapidly inhibits this "serpin-resistant" variant of t-PA. 相似文献
19.
K. H?kkinen A. Pakarinen R. U. Newton W. J. Kraemer 《European journal of applied physiology and occupational physiology》1998,77(4):312-319
Acute hormone responses of growth hormone (GH), total and free testosterone (TT and FT) and cortisol (C) to heavy resistance
isometric exercise were examined in ten young men [YM 26.5 (SD 4.8) years] and ten old men [OM 70.0 (SD 3.7) years]. Loading
conditions of the same relative intensity were created for the lower and upper extremity actions separately as well as for
both of them together – lower extremity exercise (LE; knee extension), upper extremity exercise (UE; bench press extension),
and lower and upper extremity exercise (LUE) performed simultaneously in a seated position. Single voluntary maximal isometric
actions lasting for 5 s were performed repeatedly for ten repetitions (with a recovery of 5 s) for a total of four sets. The
recovery time between the sets was 1 min. Each exercise led to large acute decreases in maximal isometric force in both YM
(P < 0.001) and OM (P < 0.001) ranging from 41% to 26% with no significant differences between the groups. Serum GH concentrations increased in
both YM (P < 0.05–0.01) and OM (P < 0.05) but the postexercise value in YM during LE was greater (P < 0.05) than for OM. The TT increased (P < 0.01–0.001) in YM in all three exercises, while in OM the increase occurred only during LE (P < 0.01). The exercises led to increases in FT in YM (P < 0.05 for LE and LUE), while in OM the increase occurred only during LUE (P < 0.05). The pre and postexercise FT were greater in YM (P < 0.001) than in OM. No significant changes occurred in C either in YM or in OM. The blood lactate concentrations increased
during the exercises in both YM (P < 0.001) and OM (P < 0.05–0.001) but the postexercise values during LE and LUE in YM were greater (P < 0.05) than in OM. The present data would indicate that the responses of GH, TT and FT to heavy resistance isometric exercise
are lowered with increasing age. The reduced acute hormone response together with the lowered basal values in FT in the older
men compared to the young men may indicate decreased anabolic effects on muscles and may explain in part the loss of muscle
mass and strength associated with aging.
Accepted: 18 August 1997 相似文献
20.
David A. Oelberg Benjamin D. Medoff Deborah H. Markowitz Paul P. Pappagianopoulos Leo C. Ginns David M. Systrom 《European journal of applied physiology and occupational physiology》1998,78(3):201-207
To determine if decreased systemic oxygen (O2) extraction contributes to the exercise limit in severe chronic obstructive pulmonary disease (COPD), 40 consecutive incremental
cycle ergometer exercise tests performed by such patients, from which a “log-log” lactate threshold (LT) was identified, were
compared to those of 8 patients with left ventricular failure (LVF) and 10 normal controls. Pulmonary gas exchange and minute
ventilation were measured continuously and arterial blood gas tensions, pH, and lactate concentrations were sampled each minute.
Cardiac output (Q˙
c) was measured by first-pass radionuclide ventriculography. The systemic O2 extraction ratio (O2ER) was calculated as arterial − mixed venous O2 content difference (C
aO2 − C
vO2)/C
aO2. Peak exercise O2 uptake (V˙O2peak) was markedly reduced in both COPD and LVF [41 (3) and 42 (3)% predicted, respectively], compared to controls [89 (2)% predicted,
P < 0.0001 for each]. Similarly, the LT occurred at a low percentage of predicted maximal oxygen consumption in both COPD and
LVF [25 (2) and 27 (3)%] compared to normals [46 (3)%, P < 0.0001 for each]. The systemic O2ER at peak exercise was severely reduced in COPD [0.36 (0.02)] compared to the other groups [P < 0.0001 for each], for whom it was nearly identical [0.58 (0.03) vs 0.63 (0.04), LVF vs control, P > 0.05]. In the COPD group, an early LT correlated with reduced systemic O2ER at peak exercise (r = 0.64, P < 0.0001), but not with any index of systemic O2 delivery. These data suggest that lactic acidemia during exercise in patients with severe COPD is better related to abnormal
systemic O2 extraction than to its delivery and contributes to the exercise limit.
Accepted: 10 March 1998 相似文献