Mechanism of the hypercoagulation effect of hyperoxia

It was shown in man and rabbits that a 30-minute inhalation of a 100% O2 under normal atmospheric pressure was accompanied by an elevation of the blood coagulation capacity and a sharp reduction of the count of platelets with the change of their structure. The trigger mechanism of the described hypercoagulation effect is possibly the viscous metamorphosis of platelets developing under the effect of oxygen activation of Hageman's factor.     

Mechanism of the hypertensive effect of droperidol in pheochromocytoma

Droperidol is used in the anaesthetic management of pheochromocytoma because of its sedative, anti-dysrhythmic and alpha-adrenoreceptor blocking properties. However, droperidol when used in pheochromocytoma, has been reported to produce a paradoxical hypertensive response. In vitro experiments with perfused rabbit ear arteries using a histochemical fluorescence technique, showed droperidol to be an inhibitor of noradrenaline uptake into sympathetic nerve endings, and this uptake inhibition was dose related. The uptake inhibition effect did not, however, produce pressor changes in experiments simulating pheochromocytoma in cats. The hypertensive response to droperidol may be due to blockade of presynaptic alpha-adrenoreceptors and this possible mechanism of action is discussed.     

Mechanism of the anti-arrhythmic effect of Rhodiola rosea extract

Critical lower limb ischaemia can occur following rectal surgery by a number of mechanisms. Patients with aorto-iliac stenosis or occlusion may be dependent on collateral circulation to the lower limbs from the visceral arteries supplying the descending colon, sigmoid colon and the rectum. Division of these collaterals can precipitate critical ischaemia of the leg. This is an uncommon scenario but one that should be considered in arteriopaths undergoing rectal surgery. Two cases of this complication are reported and the mechanisms discussed.     

Mechanism of the effect of thermotherapy as applied to AIDS

Artificially induced thermal intermittence using thermogenic agents was utilized to treat AIDS patients in an attempt to make an analogy with the sterilization process by tyndallization employed in laboratories. It is known that micro-organisms are more sensitive to discontinuous than to constant heat. The author believes that the AIDS virus may be either destroyed or weakened using this method which may also provoke an immune stimulus over the body's system of defense, especially over the bone marrow, with the consequent increase of the indexes of lymphocins, opsonins and hematogenesis.     

Mechanism of contraceptive effect of low progestin doses

The effect of megestrol-acetate and ethynodiol-triacetate on the ovulation and on the division of impregnated ovules was examined. Experiments were performed on human oocysts. The progestins were also administered to animals with normal cycle. Males were placed with the females after 3 days of treatment. The time of fecundation was determined from the presence of spermatozoa in vaginal smears. The experiments with incubation of human ovules with megestrol-acetate or ethynodiol-diacetate indicated that maturation, fecundation and development of the ovules up to 4-8 blastomeres are not hindered. This was confirmed by the data obtained from a control group. Thus no cytotoxic effect of progestin was recorded in the preovulation period of the maturation nor during fecundation. The experiments with animals revealed no change in the character of the ovulation provoked by a 14-day treatment with progestins. These results allow to conclude that the contraceptive effect of megestrol-acetate and ethynodiol-diacetate is not linked with a damaging effect on the division of the ovule during its presence in the tubes.     

Mechanism of the growth-promoting effect of serum albumin on concanavalin A-activated lymphocytes: protective effect of the plasma proteins

The concentration of concanavalin A (Con A) required for optimal growth of lymphocytes is 10 to 20 times greater in the presence of plasma than in the presence of serum albumin (BSA). This shift in Con A requirement is mainly caused by Cohn fractions III and IV, which bind and probably remove free Con A. Aymphocytes, once they are activated by Con A, lose all proliferative activity unless protected by certain proteins. Cohn fraction VI and beta-lactoglobulin were found to be most effective in protecting the cells. The protective proteins do not promote growth; only BSA promotes growth of Con A-activated lymphocytes. The mechanism of the growth-promoting effect of BSA on Con A-activated lymphocytes was investigated. The continous presence of BSA in the culture medium durdly reduces, whereas protein-free medium abolishes, growth. The mechanism of the growth-promoting effect of BSA is not concerned with regulating the uptake of Con Aby lymphocytes. Red blood cells, crenated by washing in protein-free medium, revert immediately to their normal globular shape by the addition ofBSA or FAFBSA, whereas the protective proteins fail to do so, indicating a direct effect of BSA on the external surface of the erythrocyte membrane and presumably also of the lymphocyte. The hypothesis is proposed that BSA promotes growth by conveting total structural integrity to the cell surface membrane of Con A-treated lymphocytes.     

热处理对典型低合金钢棒材力学性能影响的机理

棒材在线淬回火热处理不仅可显著降低成本,而且有利于改善材料性能.通过实验室试验、组织性能检测、有限元模拟等就典型45#钢和40Cr钢进行研究,结果表明:45#钢和40Cr钢淬硬层深度分别约为4.8,18 mm,临界冷速约72,16℃/s;600℃高温回火保温20 min后,钢中碳化物分布弥散均匀,强塑性和沿横截面均匀性...     

石油套管钢钙处理机理及效果

系统地研究了国内某钢厂生产的3 9Mn2V石油套管钢钙处理前后的总氧含量变化及夹杂物类型,从热力学上分析了钢中氧化铝和硫化锰的变性机理.研究结果表明现有工艺条件下喂入的硅钙量可以将Al₂O₃完全变性为炼钢温度下呈液态的12CaO· 7Al₂O₃和3CaO· Al₂O₃夹杂物,但不能将MnS完全变性为CaS.     

Mechanism of the effect of the ferrite grain size on the fatigue strength of a low-carbon steel

The effect of the ferrite grain size on the fatigue strength of a low-carbon steel is studied. It has been shown that, as the ferrite grain size increases, the fatigue strength decreases due to plastic-flow localization. One of the explanations of this phenomenon is the beginning of the formation of periodical cellular dislocation structures.     

低矿化度水驱中的微粒运移机理及其开发效果

低矿化度水驱作为一种经济可行的精细化注水技术,其产生的微粒运移机理能有效地改变储层物性与吸水剖面,进而达到均衡驱替和提高采收率的效果.本文基于胶体稳定性Derjaguin-Landau-Verwey-Overbeek (DLVO)理论与扩散双电层理论,从微观角度分析了注入水矿化度、离子价型等因素对黏土微粒受力与运移量的影响,通过最大滞留体积分数方程建立了微粒运移量与渗透率损伤程度间的关系.针对纵向非均质油藏特高含水期层间干扰严重的问题,开展了特高含水期转注低矿化度水驱的数值模拟研究.微粒受力分析与数值模拟结果表明,特高含水期转注低矿化度水后,分流量较多的高渗层会产生大量的黏土微粒水化膨胀、运移与堵塞作用,造成高渗层渗透率明显下降,注入水被更多地分流到水驱程度较小的中、低渗层,有效地调节了吸水剖面并缓解了层间干扰问题,相比常规海水驱可提高约3%的原油采收率,进而达到提高层间均衡动用程度与原油采收率的效果.     

低矿化度水驱中的微粒运移机理及其开发效果

低矿化度水驱作为一种经济可行的精细化注水技术, 其产生的微粒运移机理能有效地改变储层物性与吸水剖面, 进而达到均衡驱替和提高采收率的效果.本文基于胶体稳定性Derjaguin-Landau-Verwey-Overbeek (DLVO)理论与扩散双电层理论, 从微观角度分析了注入水矿化度、离子价型等因素对黏土微粒受力与运移量的影响, 通过最大滞留体积分数方程建立了微粒运移量与渗透率损伤程度间的关系.针对纵向非均质油藏特高含水期层间干扰严重的问题, 开展了特高含水期转注低矿化度水驱的数值模拟研究.微粒受力分析与数值模拟结果表明, 特高含水期转注低矿化度水后, 分流量较多的高渗层会产生大量的黏土微粒水化膨胀、运移与堵塞作用, 造成高渗层渗透率明显下降, 注入水被更多地分流到水驱程度较小的中、低渗层, 有效地调节了吸水剖面并缓解了层间干扰问题, 相比常规海水驱可提高约3%的原油采收率, 进而达到提高层间均衡动用程度与原油采收率的效果.      

Mechanism of the acute pressor effect and bradycardia elicited by diaspirin crosslinked hemoglobin in anesthetized rats

Although intracellular pH (pHi), is a regulator of numerous biological processes, it has received relatively little attention with regard to the physiology of the mammalian preimplantation embryo. Interestingly, there is some controversy as to whether the early embryo can recover from an acid load. The significance of this is that two constituents of mouse embryo culture media are pyruvate and lactate. These carboxylic acids are utilised by the early mouse embryo for energy production. However, as weak acids, pyruvate and lactate may induce perturbations in the pHi and thus alter the physiology of the embryo. The aims of this study were therefore to measure the pHi of the mouse preimplantation embryo and to determine the effect of lactate on pHi at different developmental stages. The pHi was measured using the ratio-metric fluorophore carboxy-seminaphthorhodafluor-1-acetoxymethylester (SNARF-1) in conjunction with confocal microscopy. The pHi increased significantly with development from the zygote to the morula stage. Furthermore, at concentrations greater than 5 mM, lactate caused the pHi of the zygote to become significantly more acidic. It was demonstrated that facilitative transport in association with a smaller passive component was responsible for the movement of lactate into the zygote. Metabolic studies revealed that, through their acidifying effect, weak acids caused a reduction in glycolytic activity in the early embryo. In contrast, the pHi of the compacted embryo remained unchanged by the presence of lactate in the external media. Furthermore, incubation with weak acids did not affect the rate of glycolysis in the morula. These data suggest that, by the generation of a transporting epithelium at compaction, the embryo develops the ability to regulate pHi against an acid load.