共查询到20条相似文献,搜索用时 15 毫秒
1.
Addition of N2 to the heliox used in pressure conditioning exposures reduces or suppresses the increase in convulsion threshold pressure (Pc) as well as the change in compression rate effect resulting from pressure exposures in the absence of N2; 18 atm N2 neutralizes the effect of 80 ATA total pressure so that Pc remains at a constant level throughout the conditioning period. Since N2 habituation is much slower than pressure conditioning (t1/2 6 days vs. 12 h), this precludes mere addition of pressure and N2 effects in this situation. In contrast to Pc, anesthesia tolerance of mice exposed to 80 ATA in the presence of 18 atm N2 increases even more (25%) than at the same PN2 but at a total pressure of only 18 ATA, indicating that pressure reversal of anesthesia does not extend to the habituation events. The implications of the striking asymmetry between the effects of protracted high pressure and inert gas narcotic exposures for an understanding of the nature of the supposed IG/HP antagonism are discussed. 相似文献
2.
Brauer R. W.; Dutcher J. A.; Hinson W.; Vorus W. S. 《Journal of applied physiology》1987,62(2):421-428
Exposure of CD-1 mice to subanesthetic partial pressures of N2O (0.5 atm) or N2 (10-20 atm) for periods up to 14 days results in up to 40% decreases in the mean threshold pressure eliciting type I high-pressure neurological syndrome (HPNS) seizures, and in increases up to 38% in the N2 partial pressure producing anesthesia. For all combinations of preexposure time, N2 partial pressure, as well as identity of the conditioning gas the relations between the convulsion threshold pressure (Pc) and the anesthesia N2 pressure (Pa) appear to be uniquely correlated by the equation Pa = 54.5 - 0.2(Pc - 60)1.2. The potency of N2O with respect to these habituation phenomena is between 28 and 33 times higher than that of N2, depending on the aspects compared. Evidence is presented indicating that after 14 days of habituation the animals have attained between 75 and 85% compensation for the anesthetic as well as the anticonvulsant effects of the conditioning gas. The bearing of the results on the problem of the nature of the antagonism between inert gas narcotic agents and high pressure and on the hypothesis that habituation tends toward restoration of isofluidity (or some analogous normalization process) are discussed. 相似文献
3.
Inert gas narcotics increase intrinsic pressure tolerance (1,000Pc) in CD-1 mice but interfere with development of the protective responses raising seizure thresholds during slower compression (e.g., 60Pc). This secondary narcotic effect can block up to 40% of the total attainable increase in Pc. The narcosis susceptible moiety of this compression rate effect develops early, whereas a narcosis resistant remnant accounts for increase in Pc occurring after 90 min of compression or pressure exposure. Pressure conditioning by multiday pressure exposure entails increases in both 60Pc and 1,000Pc and in virtual annullment of the compression rate effect. The effect can be completely blocked by narcotic gases in the conditioning atmosphere. In addition to blocking part of the compression rate effect the presence of narcotic gases under these conditions can reverse the effects of previously established pressure conditioning. 60Pc regresses much more slowly under these conditions than 1,000Pc. Either reversal rate is much more rapid in air at 1 ATA than at 80 ATA under 0.9 atm N2O. The implications of these data are discussed with regard to evaluation of the hypothesis of antagonism between inert gas narcotics and high pressures and to elaboration of the monoamine hypothesis to account for the modification of the compression rate effect by narcotic gases. 相似文献
4.
Films of pulmonary surfactant in the lung are metastable at surface pressures well above the equilibrium spreading pressure of 45 mN/m but commonly collapse at that pressure when compressed in vitro. The studies reported here determined the effect of compression rate on the ability of monolayers containing extracted calf surfactant at 37 degrees C to maintain very high surface pressures on the continuous interface of a captive bubble. Increasing the rate from 2 A(2)/phospholipid/min (i.e., 3% of (initial area at 40 mN/m)/min) to 23%/s produced only transient increases to 48 mN/m. Above a threshold rate of 32%/s, however, surface pressures reached > 68 mN/m. After the rapid compression, static films maintained surface pressures within +/- 1 mN/m both at these maximum values and at lower pressures following expansion at < 5%/min to > or = 45 mN/m. Experiments with dimyristoyl phosphatidylcholine at 37 degrees C produced similar results. These findings indicate that compression at rates comparable to values in the lungs can transform at least some phospholipid monolayers from a form that collapses readily at the equilibrium spreading pressure to one that is metastable for prolonged periods at higher pressures. Our results also suggest that transformation of surfactant films can occur without refinement of their composition. 相似文献
5.
J E Baumgardner I C Choi A Vonk-Noordegraaf H F Frasch G R Neufeld B E Marshall 《Journal of applied physiology》2000,89(5):1699-1708
We developed micropore membrane inlet mass spectrometer (MMIMS) probes to rapidly measure inert-gas partial pressures in small blood samples. The mass spectrometer output was linearly related to inert-gas partial pressure (r(2) of 0.996-1.000) and was nearly independent of large variations in inert-gas solubility in liquid samples. We infused six inert gases into five pentobarbital-anesthetized New Zealand rabbits and used the MMIMS system to measure inert-gas partial pressures in systemic and pulmonary arterial blood and in mixed expired gas samples. The retention and excretion data were transformed into distributions of ventilation-to-perfusion ratios (V(A)/Q) with the use of linear regression techniques. Distributions of V(A)/Q were unimodal and broad, consistent with prior reports in the normal rabbit. Total blood sample volume for each VA/Q distribution was 4 ml, and analysis time was 8 min. MMIMS provides a convenient method to perform the multiple inert-gas elimination technique rapidly and with small blood sample volumes. 相似文献
6.
K W Miller 《Federation proceedings》1977,36(5):1663-1667
The physiological effects on mammals of elevated pressures (approximately 100 atmospheres) must be considered in the context of the inert gases breathed. The most striking effect of pressure per se is a central hyperexcitability manifest at first by trembling of the entremities and finally by convulsions. Paralysis and death occur at higher pressures. The primary effects of the inert gases breathed are inert gas narcosis and general anesthesia. The exciting effects of pressure per se and the depressive effects of the inert gases tend to oppose each other. Thus consciousness may be restored to anesthetized mice by raising the pressure, and conversely the threshold pressure that causes convulsions is elevated in the presence of anesthetics. These mutually antagonistic effects can be rationalized in terms of model which proposes that both anesthetics and pressure non-specifically perturb thelipid bilayer regions of neutral membranes. This model is termed the critical volume hypothesis. Anthesthetics dissolve in and expand these lipid bilayer regions, while pressure causes mechanical compression. Expansion leads to anesthesia and compression to convulsions if a critical degree of change is achieved. At elevated partial pressures of inert gas the gas-induced expansion is opposed by the compression of pressure per se. With very insoluble gases, such as helium, this expansion is so small that net compression results and the effects of helium differ little from those of pressure per se. With more soluble gases, such as nitrogen, net expansion results in inert gas narcosis and anesthesia. The critical volume hypothesis enables "safe" mixtures of "expanding" and "compressing" gases to be defined. These enable higher pressures to be better tolerated by mammals. 相似文献
7.
Kallmeyer J Ferdelman TG Jansen KH Jørgensen BB 《Journal of microbiological methods》2003,55(1):165-172
Details about the construction and use of a high-pressure thermal gradient block for the simultaneous incubation of multiple samples are presented. Most parts used are moderately priced off-the-shelf components that easily obtainable. In order to keep the pressure independent of thermal expansion of the sample vessels, a back-pressure system with a constant leak rate was installed. Pressure is applied through high-pressure liquid chromatography (HPLC) pumps that run in constant pressure mode with variable flow rate, thereby regulating any pressure fluctuations. The device allows incubations along a wide range of temperatures and pressures and can easily be modified to accommodate different experiments, either biological or chemical. As an application, we present measurements of bacterial sulfate reduction rates in hydrothermal sediments from Guyamas Basin over a wide range of temperatures and pressures. Sulfate reduction rates increase with increasing pressure and show maximum values at pressures higher than in situ. 相似文献
8.
The effect of the force of compression on expiratory flow was evaluated in 19 infants (2-13 mo of age) with respiratory illnesses of varying severity. An inflatable cuff was used to compress the chest and abdomen. Expiratory flow and volume, airway occlusion pressure, cuff pressure (Pc), and functional residual capacity were measured. Transmission of pressure from cuff to pleural space was assessed by a noninvasive occlusion technique. Close correlations (P less than 0.001) were found between Pc and the change in pleural pressure with cuff inflation (delta Ppl,c). Pressure transmission was found to vary between two cuffs of different design and between infants. Several forced expirations were then performed on each infant at various levels of delta Ppl,c. Infants with low maximal expiratory flows at low lung volumes required relatively gentle compression to achieve flow limitation and showed decreased flow for firmer compressions. Flow-volume curves in each infant tended to become more concave as delta Ppl,c increased. These findings underline the importance of knowledge of delta Ppl,c in interpreting expiratory flow-volume curves in infants. 相似文献
9.
Deep pressure sores (DPS) are associated with inadequate soft tissue perfusion and excessive tissue deformation over critical time durations, as well as with ischemia-reperfusion cycles and deficiency of the lymphatic system. Muscle tissue shows the lowest tolerance to pressure injuries, compared with more superficial tissues. In this communication, we present new histopathology data for muscle tissue of albino (Sprague-Dawley) rats exposed to pressures for 15 or 30 min. These data are superimposed with an extensive literature review of all previous histopathology reported for albino rat skeletal muscles subjected to pressure. The pooled data enabled a new mathematical characterization of the pressure-time threshold for cell death in striated muscle of rats, in the form of a sigmoid pressure-time relation, which extends the previous pressure-time relation to the shorter exposure periods. We found that for pressure exposures shorter than 1 h, the magnitude of pressure is the important factor for causing cell death and the exposure time has little or no effect: even relatively short exposures (15 min - 1 h) to pressures greater than 32 kPa (240 mmHg) cause cell death in rat muscle tissue. For exposures of 2 h or over, again the magnitude of pressure is the important factor for causing cell death: pressures greater than 9 kPa (67 mmHg) applied for over 2 h consistently cause muscle cell death. For the intermediate exposures (between 1 and 2 h), the magnitude of cell-death-causing pressure strongly depends on the time of exposure, i.e., critical pressure levels drop from 32 to 9 kPa. The present sigmoidal pressure-time cell death threshold is useful for design of studies in albino rat models of DPS, and may also be helpful in numerical simulations of DPS development, where there is often a need to extrapolate from tissue pressures to biological damage. 相似文献
10.
摘要 目的:探究骨质疏松性椎体压缩骨折经皮椎体后凸成形术中应用不同麻醉方式对疼痛阈值的影响。方法:选择120例接受经皮椎体后凸成形术治疗的骨质疏松性椎体压缩骨折患者,并将其随机分为全身麻醉组(n=40)、局部麻醉组(n=40)和硬膜外麻醉组(n=40)。对比分析三组麻醉效果、不同时间点疼痛阈值(VAS值)、疼痛总分(PRI)与疼痛强度(PPI)、温度疼痛阈值和电疼痛阈值以及采取自控镇痛、止痛药的情况。结果:全身麻醉组患者麻醉优良率为95.00 %,局部麻醉组患者麻醉优良率为87.50 %,硬膜外麻醉组患者麻醉优良率为92.50 %。三组患者麻醉效果比较,全身麻醉组显著优于局部麻醉组和硬膜外麻醉组(P<0.05)。随着麻醉时间的延长,硬膜外麻醉组患者在麻醉后的VAS值、PRI和PPI值、温度疼痛阈值和电疼痛阈值均显著低于全身麻醉组和局部麻醉组患者(P<0.05)。全身麻醉组采取其他方式进行止痛的概率为1.67 %,局部麻醉组为30.00 %,硬膜外麻醉组为2.50 %,差异有统计学意义(P<0.05)。结论:硬膜外麻醉方式对骨质疏松性椎体压缩骨折经皮椎体后凸成形术的麻醉效果和镇痛效果较全身麻醉和局部麻醉效果好,值得临床推广使用。 相似文献
11.
We have developed a model including three serial compliant compartments (arterial, capillary, and venous) separated by two resistances (arterial and venous) for interpreting in vivo single pulmonary arterial or venous occlusion pressure profiles and double occlusion. We formalized and solved the corresponding system of equations. We showed that in this model 1) pulmonary capillary pressure (Pc) profile after arterial or venous occlusion has an S shape, 2) the estimation of Pc by zero time extrapolation of the slow component of the arterial occlusion profile (Pcao) always overestimates Pc, 3) symmetrically such an estimation on the venous occlusion profile (Pcvo) always underestimates Pc, 4) double occlusion pressure (Pcdo) differs from Pc. We evaluated the impact of varying parameter values in the model with parameter sets drawn either from the literature or from arbitrary arterial and venous pressures, being respectively 20 and 5 mmHg. Resulting Pcao-Pc differences ranged from 0.4 to 5.4 mmHg and resulting Pcvo-Pc differences ranged from -0.3 to -5.0 mmHg. Pcdo-Pc was positive or negative, its absolute value in general being negligible (< 1.1 mmHg). 相似文献
12.
The osmotic reflection coefficient (sigma) for total plasma proteins was estimated in 11 isolated blood-perfused canine lungs. Sigma's were determined by first measuring the capillary filtration coefficient (Kf,C in ml X min-1 X 100g-1 X cmH2O-1) using increased hydrostatic pressures and time 0 extrapolation of the slope of the weight gain curve. Kf,C averaged 0.19 +/- 0.05 (mean +/- SD) for 14 separate determinations in the 11 lungs. Following a Kf,C determination, the isogravimetric capillary pressure (Pc,i) was determined and averaged 9.9 +/- 0.5 cmH2O for all controls reported in this study. Then the blood colloids in the perfusate were either diluted or concentrated. The lung either gained or lost weight, respectively, and an initial slope of the weight gain curve (delta W/delta t)0 was estimated. The change in plasma protein colloid osmotic pressure (delta IIP) was measured using a membrane osmometer. The measured delta IIP was related to the effective colloid osmotic pressure (delta IIM) by delta IIM = (delta W/delta t)0/Kf,C = sigma delta IIP. Using this relationship, sigma averaged 0.65 +/- 0.06, and the least-squares linear regression equation relating Pc,i and the measured IIP was Pc,i = -3.1 + 0.67 IIP. The mean estimate of sigma (0.65) for total plasma proteins is similar to that reported for dog lung using lymphatic protein flux analyses, although lower than estimates made in skeletal muscle using the present methods (approximately 0.95). 相似文献
13.
We have studied the effect of alveolar hypoxia on fluid filtration characteristics of the pulmonary microcirculation in an in situ left upper lobe preparation with near static flow conditions (20 ml/min). In six dogs (group 1), rate of edema formation (delta W/delta t, where W is weight and t is time) was assessed over a wide range of vascular pressures under two inspired O2 fraction (FIO2) conditions (0.95 and 0.0 with 5% CO2-balance N2 in both cases). delta W/delta t was plotted against vascular pressure, and the best-fit linear regression was obtained. There was no significant difference (paired t test) in either threshold pressure for edema formation [18.3 +/- 1.8 and 17.1 +/- 1.2 (SE) mmHg, respectively] or the slopes (0.067 +/- 0.008 and 0.073 +/- 0.017 g.min-1. mmHg-1.100g-1, respectively). In another seven dogs (group 2), delta W/delta t was obtained at a constant vascular pressure of 40 mmHg under four FIO2 conditions (0.95, 0.21, 0.05, and 0.0, with 5% CO2-balance N2). Delta W/delta t for the four conditions averaged 0.60 +/- 0.11, 0.61 +/- 0.11, 0.61 +/- 0.10, and 0.61 +/- 0.10 (SE) g.min-1.mmHg-1.100g-1, respectively. No significant differences (ANOVA for repeated measures) were noted. We conclude that alveolar hypoxia does not alter the threshold for edema formation or delta W/delta t at a given microvascular pressure. 相似文献
14.
The impact of high pressure and freezing on survivability of Escherichia coli and human red blood cells was evaluated to determine the utility of high-pressure transitions for preserving living cells. Based on microscopy and survivability, high pressures did not directly impact physical damage to living cells. E. coli studies showed that increased cell death is due to indirect phenomena with decreasing survivability at increasingly high pressures and exposure times. Pressurization rates up to 1.4kbar/min had negligible effects relative to exposures of >5min at high pressures.Both glycine and control of pH near 7.0 were successful in reducing the adverse impacts of high pressure. Survivability increased from <1% at 5min exposure to 2.1kbar of pressure to typical values >20%. The combination of glycine and the buffer salt led to even further improvements in survivability. Pressure changes were used to traverse temperature and pressures consistent with Ice I and Ice III phase boundaries of pure water. 相似文献
15.
《IRBM》2023,44(3):100753
ObjectivesPressure ulcers are a great handicap for those who develop one. Pressure ulcers can take a long time to heal especially if detected late. These afflictions require a lot of time from the medical personnel and thus a great amount of money. We aim here to check the impact of continuous measurement on the performance of early pressure ulcer detection algorithms.Material and methodsTo detect pressure ulcers early on we use a simulation of a human buttocks to simulate the reaction of it to pressure. This simulation considers the most recent findings about pressure ulcers. In particular, the phenomenon of muscle stiffening when pressure is applied for a long period of time, and the reperfusion phenomenon. We can then simulate pressure captors on the outside interface of the buttocks to use these measurements for detection. We then determine the best threshold on the measured pressures to create standard algorithms that we compare to novel algorithms using an optimized threshold on a calculated damage based on the pressure measurement of the last 2 hours.ResultsWe compare these different algorithms for the early detection of pressure ulcers and show the need to take the measurement variation in time for a better detection. The detection error is improved by 7.3% for balanced classes and 2.7% for a dataset with a majority of healthy buttocks.ConclusionWe showed that taking the evolution of pressure instead of only instantaneous measurement can improve the early detection of pressure ulcer. 相似文献
16.
Segmental vascular resistances and compliances in dog lung 总被引:1,自引:0,他引:1
Rippe B.; Parker J. C.; Townsley M. I.; Mortillaro N. A.; Taylor A. E. 《Journal of applied physiology》1987,62(3):1206-1215
The segmental distribution of vascular resistances and compliances were evaluated in isolated blood perfused lung lobes using arterial, venous, and double-occlusion pressures and were compared with filtration midpoint capillary pressures (Pc,f). We separated total vascular resistance (RT) and compliance (CT) into large artery (Ra, Ca), large vein (Rv, Cv), and microvascular compartments (Rmc, Cmc) at base-line and increased vascular pressures and during infusions of histamine, serotonin, and norepinephrine. In control lobes, double-occlusion pressure (Pdo) closely approximated Pc,f at all vascular pressures. Pre- and postcapillary resistance were approximately equal when referenced to either Pc,f or Pdo. Although Rmc comprised 42% of RT and Cmc constituted 76% of CT, a twofold increase in base-line Pc,f caused RT to decrease to 67% and Rmc/RT to 29% of control values, whereas CT decreased to 87% and Cmc/CT decreased to 88% of control values over the same Pc,f range. Mean static CT was 2.25 +/- 0.09 ml X cmH2O-1. 100 g-1, whereas dynamic CT was 1.54 +/- 0.08 ml X cmH2O-1. 100 g-1, or only 68% of static vascular compliance. Drug infusions increased mean RT from 4.2- to 5.3-fold and significantly decreased both static and dynamic CT. Although all vascular segments were constricted, histamine affected primarily large veins, serotonin increased Ra greater than Rv, and norepinephrine constricted upstream and downstream vessels about equally. Increased Pc,f in the presence of these drugs decreased RT significantly in every case primarily through attenuation of the drug vasoconstrictor effect on Rmc and decreased CT primarily due to a decrease in Cmc, but increased Cmc/(Ca + Cv). Thus the microvascular compartment appears to be the major site of both fluid filtration and vascular compliance and contributes significantly to total vascular resistance. Drug infusions constricted large and small vessel compartments as defined here, but increased Pc,f attenuated microvascular vasoconstriction and to a lesser extent large vessel vasoconstriction resulting in a reduced microvascular resistance in both drug-treated and control lobes. This effect can be attributed to recruitment and/or distension of microvessels and distension of larger vessels. 相似文献
17.
摘要 目的:探讨臂丛神经阻滞复合静脉全麻进行锁骨骨折手术对患者疼痛阈值和术后谵妄的影响。方法:选取本院2018年4月-2021年5月收治的100例锁骨骨折患者作为研究对象,随机将其分为观察组(n=50)和对照组(n=50)。观察组采用臂丛神经阻滞复合静脉全麻进行手术,对照组单独采用静脉全麻进行手术,对比两组患者手术时间、住院时间以及唤醒时间;不同时间生命体征;麻醉效果和术后疼痛阈值;术后谵妄发生率、谵妄持续时间以及每天睡眠时间。结果:观察组患者的术后住院时长以及唤醒时间明显低于对照组(P<0.05)。观察组T1到T4时间血氧饱和度(SPO2)、收缩压(SBP)、舒张压(DBP)、平均动脉压(MAP)、心率(HR)无明显波动,对照组T1到T4时间上述指标波动明显,且两组患者T2、T3时间SPO2、SBP、DBP、MAP、HR对比差异显著(P<0.05);观察组患者的COR、NE在T2、T3明显下降,而对照组的COR在T2、T3呈上升趋势(P<0.05)。观察组运动神经阻滞时间以及感觉神经阻滞时间明显高于对照组(P<0.05),术后2 h、12 h、24 h疼痛阈值明显低于对照组(P<0.05)。观察组术后谵妄发生率和谵妄持续时间明显低于对照组(P<0.05)。结论:对锁骨骨折手术患者进行臂丛神经阻滞复合静脉全麻,有效降低患者手术时间、住院时间以及唤醒时间,同时稳定患者生命体征,提升麻醉效果,降低术后疼痛阈,并且谵妄发生率、谵妄持续时间以及每天睡眠时间相对较低。 相似文献
18.
Effect of Pressure on the Release of Radioactive Glycine and γ-Aminobutyric Acid from Spinal Cord Synaptosomes 总被引:1,自引:1,他引:0
Exposure to high hydrostatic pressure produces neurological changes referred to as the high-pressure nervous syndrome (HPNS). Manifestations of HPNS include tremor, EEG changes, and convulsions. These symptoms suggest an alteration in synaptic transmission, particularly with inhibitory neural pathways. Because spinal cord transmission has been implicated in HPNS, this study investigated inhibitory neurotransmitter function in the cord at high pressure. Guinea pig spinal cord synaptosome preparations were used to study the effect of compression to 67.7 atmospheres absolute on [3H]glycine and [3H]gamma-aminobutyric acid ([3H]GABA) release. Pressure was found to exert a significant suppressive effect on the depolarization-induced calcium-dependent release of glycine and GABA by these spinal cord presynaptic nerve terminals. This study suggests that decreased tonic inhibitory regulation at the level of the spinal cord contributes to the hyperexcitability observed in animals with compression to high pressure. 相似文献
19.
Daniel K Mulkey Richard A Henderson Robert W Putnam Jay B Dean 《Journal of applied physiology》2003,95(3):922-930
Neuronal sensitivity to pressure, barosensitivity, is illustrated by high-pressure nervous syndrome, which manifests as increased central nervous system excitability when heliox or trimix is breathed at >15 atmospheres absolute (ATA). We have tested the hypothesis that smaller levels of pressure (相似文献
20.
Organization of microsomal UDP-glucuronosyltransferase. Activation by treatment at high pressure 总被引:1,自引:0,他引:1
Treatment of microsomes at pressures as high as 2.25 kbar led to an apparent irreversible activation of UDP-glucuronylsyltransferase when pressure was released. The response of the enzyme to pressure, as reflected by activity measured after release of pressure, appeared to be discontinuous in that no activation was seen for any preparation at pressures less than 1.2 kbar. In addition, activation was temperature dependent. Maximum activation at 2.25 kbar occurred at about 12 degrees C; the extent of activation in 10 min was less for either higher or lower temperatures. Activation was also time dependent. Maximum activation at 2.25 kbar and 9 degrees C required 90 min of pressure treatment. Activation appeared to occur more slowly at lower pressure. Pressure-induced activation was associated with a loss of sensitivity of the enzyme to allosteric activation by UDP-N-Ac-Glc and a conversion of the kinetic pattern from non-Michaelis-Menten to Michaelis-Menten. Pressure did not activate enzyme that had previously been activated maximally by adding detergent to microsomes. Pressure also did not activate pure UDP-glucuronosyltransferase reconstituted into unilamellar vesicles of dioleoylphosphatidylcholine. Pressure treatment did not release UDP-glucuronosyltransferase from microsomes into water. Pressure had a continuous effect on the polarization and excimer/monomer formation of fluorescent probes incorporated into microsomes, and the properties returned essentially to their values at 1 atm when pressure was released. Measurements of activity at 2.2 kbar showed that pressure-induced activation of UDP-glucuronosyltransferase in microsomes occurred via two intermediates that were inactive and that the activated state of the enzyme was generated during/after release of pressure.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献