Microcirculatory responses to carotid sinus nerve stimulation at various ambient O2 tension in the rabbit tenuissimus muscle

To quantify the integrated effects of local and central control mechanisms through tissue metabolites and the autonomic nervous system on the peripheral vascular beds, microcirculatory responses to the carotid sinus nerve stimulation at various levels of ambient oxygen tension (PO2) were measured in the rabbit tenuissimus muscle suffused with oxygenated Tyrode solution, using a microscope-TV system. The statistical analysis of the experimental data exhibited that both capillary red cell velocity and perfused capillary density at the control state were significantly decreased as PO2 was elevated (P less than 0.01) and that the stimulation also significantly augmented their values (P less than 0.01) except for the peak velocity data. Regression analysis indicated that both the velocity and density responses to PO2 changes during stimulation were less sensitive than those at the control state. For instance, the vasodilating effect of stimulation on density at PO2 20 mm Hg was enhanced by about four-fold at 80 mm Hg, although the effect on velocity was increased only by 16% with the same PO2 change. From these results, it was concluded that the microcirculatory changes due to the arteriolar smooth muscle contraction evoked by unit sympathetic discharge was significantly influenced by the ambient PO2 level. Such synergistic interaction of the local and central control mechanisms like a series-coupled gain control system was suspected to play an important role in the overall regulation of the microcirculation.     

Capillary diameter in rat heart in situ: Relation to erythrocyte deformability,O2 transport,and transmural O2 gradients

The diameter of subepicardial capillaries was measured in stop-motion photo-micrographs of normoxic rat hearts. Mean diameter over the whole cardiac cycle was 4.41 μm (0.09, SEM). Calculations indicate that mean diameter during systole is about 4 μm and during diastole is about 5 μm. The deformability of rat erythrocytes was evaluated by aspirating the cells into micropipets of various diameters. All cells traversed a 2.8-μm pipet at a mean ΔP of 0.17 mm Hg and a 2.5-μm pipet at a ΔP of 2.9 mm Hg. Below 2.5 μm, the pressure required to aspirate 100% of the cells increased linearly as the channel diameter decreased and reached 104 mm Hg at 1.9 μm. Comparison of deformability data with frequency distributions of coronary capillary diameter indicates that all cells traverse all capillaries during diastole and traverse most superficial capillaries during systole. In the subendocardium, however, systolic tissue pressure is very high relative to erythrocyte deformability. Consequently, perfused capillaries should be compressed to the minimum thickness of an erythrocyte (about 1.8 μm). Calculated pericapillary O₂ gradients demonstrate that such narrow capillaries cannot sustain aerobic metabolism throughout the tissue. This is particularly true since capillary compression impedes erythrocyte entry, and thereby increases functional intercapillary distance. We conclude that: (1) Compression and narrowing of capillaries during systole can account for the transmural gradient in tissue pO₂. (2) During diastole, capillary dimensions are perfectly matched to the dimensions and deformability of erythrocytes.     

Blood O2 saturation determination in frozen tissue

We have developed a method for microspectrophotometric determination of oxygen saturation in small arteries and veins of a quick-frozen tissue. Optical densities of 10- to 30-μm sections of frozen dog blood were determined with a Zeiss microspectrophotometer, and oxygen saturation was determined by a three-wavelength (560, 523, 506 nm) method. Blood sections were covered with silicone oil to prevent O₂ diffusion. Calibration lines were constructed by comparing absorbance ratios computed by the three-wavelength method against blood O₂ saturation determined by the Van Slyke method. The method was tested in arteries and veins of frozen dog gracilis muscle against Van Slyke. The mean saturation determined from three different vessels had an accuracy of ±2.6%.     

O157：H7致泻性大肠杆菌感染

大肠杆菌分为致病性大肠杆菌和非致病性大肠杆菌或普通大肠杆菌。O157：H7大肠杆菌属于致病性大肠杆菌中的致泻性大肠杆菌,并因其菌体抗原“0”排序第157,鞭毛抗原“H”排序第7而得名。感染后能引起出血性肠炎、血栓性血小板减少性紫癜和溶血尿毒症综合征(HUS),故是一种比较严重的致病性大肠杆菌感染。     

严重代谢性碱中毒时CO2潴留的处理

代谢性碱中毒是指细胞外液碱增多和(或)H~+丢失引起血液pH升高,以血浆HCO_3~-原发性增多为特征,动脉血二氧化碳分压(PaCO_2)可代偿性增高,一般极少超过55 mmHg。然而,在极其严重代谢性碱中毒情况下,PaCO_2代偿极限可达60~72 mmHg,但目前国内外鲜有此类报道。本文探讨了我院成功抢救的1例严重代谢性碱中毒患者,以提高对该罕见临床现象的认识。     

Parameter optimization of CO2 casting process by using Taguchi method

This study demonstrates optimization of CO₂ casting process parameters by using Taguchi’s design of experiments method. The CO₂ casting process involves a large number of parameters affecting the various quality features of the final product. The process parameters considered in this research work are weight of CO₂ gas, mould hardness number, sand particle size, percentage of sodium silicate, sand mixing time, pouring time, pouring height, pouring temperature, and cooling time of poured metal. The effect of the selected process parameters on casting defects and subsequent setting of the parameters have been accomplished by using Taguchi’s parameter design approach. The result indicates that the selected process parameters significantly affect the defects of CO₂ casting. The results are further conformed by conducting confirmation experiments.     

长时间气腹对全麻后肺萎陷的影响

目的观察腹腔镜胃癌根治术患者术中功能残气量(FRC)和动脉血气分析的变化,研究长时间气腹对全麻后肺萎陷的影响。方法选择择期行腹腔镜胃癌根治术患者30例。分别于诱导气管插管后10 min(T0)和气腹后30 min(T1)、60 min(T2)、2 h(T3)、3 h(T4)抽取患者桡动脉血行血气分析,记录pH值、动脉血氧分压(PaO_2)、动脉血气CO2分压(Pa CO2);同时采用密闭式氦稀释法测量FRC。结果与T0比较,T1、T2、T3时患者FRC明显降低(P0.01);与T3比较,T4时患者FRC差异无统计学意义(P0.01)。与T0比较,T1时PaO_2差异无统计学意义(P0.01),T2、T3时明显降低(P0.01)。与T3比较,T4时患者PaO_2差异无统计学意义(P0.01)。结论长时间气腹可加重全麻后肺萎陷,并导致PaO_2降低。     

CO2激光治疗丝状疣的临床疗效观察

目的 观察CO2激光治疗丝状疣的疗效.方法 将180例丝状疣患者随机分为治疗组95例,予CO2激光治疗,对照组85例予液氮冷冻治疗,4周后观察并评价疗效.结果 治疗组痊愈率为97.89%,高于对照组的82.35%(P＜0.05);治疗组不良反应发生率为2.1%,显著低于对照组的41.18%(P＜0.05).结论 CO2激光治疗丝状疣治愈率高,治疗次数少,不良反应少,效果优于液氮冷冻治疗,值得临床推广使用.     

V̇O2 of resting muscle during arterial hypoxia: Role of reflex vasoconstriction

To examine the influence of chemoreflex vasoconstriction on the change in O₂ consumption in resting muscle during arterial hypoxia, responses in intact and denervated gracilis muscles were compared. Hypoxia was induced in anesthetized, paralyzed, and artificially ventilated dogs by inhalation of low O₂ gases. Electromagnetic blood flow, AVO₂ difference, and O₂ consumption were measured. Small vessel blood content served as relative index of open capillary density. Before denervation, muscle O₂ consumption was maintained during hypoxia, unless SaO₂ fell below 50%. Maintenance of muscle O₂ consumption during hypoxia was associated with an unchanging AVO₂ difference, a large increase in small vessel blood content, and a minimal increase in flow. Relative changes in parameters of O₂ supply and demand during hypoxia were not significantly different after denervation, except that flow increases were modestly higher. Results suggest that O₂ delivery to muscle during hypoxia is maintained primarily by an opening of capillaries rather than by increases in flow and that chemoreflex vasoconstriction does not interfere with this local vascular adjustment.     

超脉冲二氧化碳点阵激光联合湿润烧伤膏治疗痤疮瘢痕的临床观察

目的观察超脉冲二氧化碳点阵激光联合湿润烧伤膏治疗痤疮瘢痕的临床疗效。方法将60例痤疮瘢痕患者随机分为两组,每组30例,治疗组采用超脉冲二氧化碳点阵激光联合湿润烧伤膏进行治疗,对照组采用超脉冲二氧化碳点阵激光联合红霉素眼膏进行治疗,观察比较两组临床疗效,并随访半年。结果治疗组瘢痕改善指数明显优于对照组,差异有统计学意义(Z=2.170,P=0.029)。结论超脉冲二氧化碳点阵激光联合湿润烧伤膏治疗痤疮瘢痕疗效优于超脉冲激光联合红霉素眼膏方法治疗,无明显副作用,且使用方便,效果良好。     

Phospholipase A2 Biochemistry

The phospholipase A₂ (PLA₂) superfamily consists of many different groups of enzymes that catalyze the hydrolysis of the sn-2 ester bond in a variety of different phospholipids. The products of this reaction, a free fatty acid, and lysophospholipid have many different important physiological roles. There are five main types of PLA₂: the secreted sPLA₂’s, the cytosolic cPLA₂’s, the Ca²⁺independent iPLA₂’s, the PAF acetylhydrolases, and the lysosomal PLA₂’s. This review focuses on the superfamily of PLA₂ enzymes, and then uses three specific examples of these enzymes to examine the differing biochemistry of the three main types of these enzymes. These three examples are the GIA cobra venom PLA₂, the GIVA cytosolic cPLA₂, and the GVIA Ca²⁺-independent iPLA₂.     

MicroRNA调控主动脉夹层发病的研究进展

主动脉夹层(aortic dissection,AD)是一种由于中层退行性变导致的极其凶险的主动脉疾病,死亡率及并发症率高居不下。目前越来越多研究证明,MicroRNA在主动脉夹层中发病机制中起重要的调控作用。本文就MicroRNA对血管平滑肌细胞、细胞外基质、血管炎症及粥样硬化及黏着斑等的影响,与主动脉夹层发病的关系做一综述。     

连续性血液净化治疗重度中暑患者的临床研究

目的:比较连续性血液净化与控温毯治疗重度中暑患者的疗效。方法:根据随机数字表法将30例重度中暑患者分为观察组和对照组,每组15例。观察组患者采用连续性血液净化降温,对照组采用控温毯降温,观察2组治疗后1、2、3、6h直肠温度下降情况;流式细胞仪检测治疗后0、1、3、6 h白细胞值、ELISA法检测白细胞NF-κB蛋白、血清C反应蛋白、降钙素原;Western blot法检测白细胞热休克蛋白70(Hsp70)表达。结果:观察组直肠温度下降幅度大于对照组(P0.05);白细胞、C反应蛋白、降钙素原、NF-κB蛋白下降幅度大于对照组(P0.05),观察组白细胞HSP70蛋白表达水平高于对照组(P0.05)。结论:连续性血液净化用于重度中暑降温效果优于控温毯降温法,其机制可能为降低血清炎症指标、升高白细胞HSP70蛋白表达。     

H2O2 Release from Filtration Leukapheresis-Procured Leukocytes

Abstract. Filtration leukapheresis-procured leukocytes (FL-leukocytes), which were collected by the elution of filtration columns with vigorous tapping, released a certain amount of H₂O₂, even in the absence of any phagocytic stimuli. Furthermore, FL-leukocytes, eluted with either gentle or vigorous tapping, exhibited a marked release of H₂O₂ during phagocytosis. The myeloperoxidase (MPO) activity of FL-leukocytes was lower than that of leukocytes collected by the dextran sedimentation method (DS-leukocytes). The data suggest that the release of both H₂O₂ and MPO from FL-leukocytes may be related to adverse transfusion reactions and abnormal post-transfusion kinetics of FL-leukocytes due to their toxic effects on living cells.