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Non-uniformity of regional contraction may be both spatial and temporal. This study was undertaken to deal with the temporal aspects of shortening and to quantify non-uniformity with regard to timing. Nine cats were anaesthetized and artificially ventilated. Two pairs of ultrasonic crystals were situated in the anterior midwall of the left ventricle to measure regional shortening. One pair, longitudinal segment, was oriented to align with midwall fibres. The other pair, transverse segment, was placed perpendicular to the first one. Registrations in control state, during caval occlusion, and during aortic constriction were carried out with and without isoprenaline infusion. Cyclic events were analysed in terms of phase angle, 0-2 pi representing one heart cycle. Transverse segments showed marked shift of duration of shortening, from 1.19 pi +/- 0.06 pi (mean +/- SEM) in the control state to 0.40 pi +/- 0.14 pi during caval occlusion with isoprenaline infusion. Duration of shortening of longitudinal segments showed less prominent shift with mean values between 1.38 pi and 1.11 pi. Regional uniformity of timing, expressed as synchronization index, varied markedly with interventions (P less than 0.0005). Dyssynchrony was most prominent during caval occlusion with mean values less than 0.6. A simple model of force generation for the two segments visualizes that segment shortening of the transverse segment is of shorter duration than the longitudinal segment and a common mechanism for temporal and spatial non-uniformity within a region could be elaborated. This study quantifies both the time course of shortening and temporal non-uniformity of two cross-oriented segments within the same myocardial region. 相似文献
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We report an adult female with a rare giant choledochal cyst. The patient presented following a normal pregnancy with the classical triad of an abdominal mass associated with jaundice and right upper quadrant abdominal pain. The cyst was excised using an intramural technique and biliary reconstruction achieved with a Roux-en-Y hepaticojejunostomy. Our patient has remained well with no evidence of malignancy over a 12 year review period. The aetiology and current management of this condition are discussed. 相似文献
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Na+ dependence of in vitro pancreatic amylase release 总被引:1,自引:0,他引:1
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Determination of optimal cryoprotectants and procedures for their addition and removal from human spermatozoa 总被引:9,自引:7,他引:9
The objective was to test the hypothesis that the optimal cryoprotective
agent for cryopreservation of human spermatozoa would be a solute for which
cells have the highest plasma membrane permeability, resulting in the least
amount of volume excursion during its addition and removal. To test this
hypothesis, theoretical simulations were performed using membrane
permeability coefficients to predict optimal procedures for the addition
and removal of a cryoprotectant. Simulations were performed using data from
four different cryoprotectants: (i) glycerol, (ii) dimethyl sulphoxide,
(iii) propylene glycol and (iv) ethylene glycol. Thermodynamic formulations
were applied to determine approaches for the addition and removal of 1 M
and 2 M final concentrations of cryoprotectant, allowing the spermatozoa to
maintain a cell volume within their osmotic tolerance limits. Based on
these data, ethylene glycol was predicted to be optimal for minimizing
volume excursions among the solutes evaluated. These predictions were then
experimentally tested using glycerol as the control cryoprotectant and
ethylene glycol as the experimental cryoprotectant. The results indicate
that there was a higher (P < 0.05) recovery of motile spermatozoa after
cryopreservation when using 1 M ethylene glycol than with 1 M glycerol,
supporting the hypothesis that use of the cryoprotectant for which the cell
has the highest permeability will result in higher cell survival.
相似文献
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