Myocardial perfusion monitoring during coronary artery bypass using an electrocardiogram-triggered laser Doppler technique

Electrocardiogram (ECG)—triggered laser Doppler perfusion monitoring (LDPM) was used to assess myocardial perfusion, with minimum myocardial tissue motion influence, during coronary artery bypass grafting (CABG). Thirteen subjects were investigated at six phases: pre- and post-CABG; post aorta cross-clamping; pre and post left internal mammary artery (LIMA) graft declamping; and post aorta declamping. The perfusion signal was calculated in late systole and late diastole, with expected minimum tissue motion, and compared with arrested heart measurements. Patient conditions or artifacts caused by surgical activity made it impossible to perform and analyse data in all six phases for some patients. No significant (n=5) difference between perfusion signals pre- and post-CABG was found. Diastolic perfusion signal levels were significantly (p<0.02) lower compared with systolic levels. After aorta cross-clamping, the signal level was almost zero. A distinct perfusion signal increase after LIMA and aorta declamping, compared with pre-LIMA declamping, was found in ten cases out of 13. A significantly (p<0.04) lower perfusion signal in the arrested heart compared with in the beating heart was registered. Influence from mechanical ventilation was observed in 14 measurements out of 17. In conclusion, ECG-triggered LDPM can be used to assess myocardial perfusion during CABG. Perfusion signals were lower in the arrested heart compared with in the beating heart and in late diastole compared with late systole. No significant difference between pre- and post-CABG was found.     

An intravital microscopic study of the hepatic microcirculation in cirrhotic mice models: relationship between fibrosis and angiogenesis

This intravital fluorescence microscopy (IVFM) study validates cirrhotic mice models and describes the different intrahepatic alterations and the role of angiogenesis in the liver during genesis of cirrhosis. Cirrhosis was induced by subcutaneous injection of carbon tetrachloride (CCl₄) and by common bile duct ligation (CBDL) in mice. Diameters of sinusoids, portal venules (PV), central venules (CV) and shunts were measured at different time points by IVFM. Thereafter, liver samples were taken for sirius red, CD31, Ki67, vascular endothelial growth factor (VEGF) and α‐smooth muscle actin (α‐SMA) evaluation by immunohistochemistry (IHC). In parallel with fibrogenesis, hepatic microcirculation was markedly disturbed in CCl₄ and CBDL mice with a significant decrease in sinusoidal diameter compared to control mice. In CCl₄ mice, CV were enlarged, with marked sinusoidal‐free spaces around CV. In contrast, PV were enlarged in CBDL mice and bile lakes were observed. In both mice models, intrahepatic shunts developed gradually after induction. During genesis of cirrhosis using CD31 IHC we observed a progressive increase in the number of blood vessels within the fibrotic septa area and a progressively increase in staining by Ki67, VEGF and α‐SMA of endothelial cells, hepatocytes and hepatic stellate cells respectively. In vivo study of the hepatic microcirculation demonstrated a totally disturbed intrahepatic architecture, with narrowing of sinusoids in both cirrhotic mice models. The diameters of CV and PV increased and large shunts, bypassing the sinusoids, were seen after both CCl₄ and CBDL induction. Thus present study shows that there is angiogenesis in the liver during cirrhogenesis, and this is probably due partially to an increased production of VEGF.     

Cathepsin B in gingival crevicular fluid of adult periodontitis patients: Identification by immunological and enzymological methods

Cathepsin B (EC 3.4.22.1), a typical lysosomal cysteine proteinase was identified immunologically with anti-human cathepsin B antibody in inflammatory exudate, gingival crevicular fluid (GCF) of adult periodontitis patients. The sensitive enzyme immunoassay (EIA) system initially developed, was rarely influenced by the presence of endogenous, cysteine proteinase inhibitors, cystatin(s), indicating that it is possible to quantify the gross amount of cathepsin B including free enzyme forms and enzyme-inhibitor complex forms using this EIA system. The cathepsin B levels in, GCF as determined by EIA and the activity measured with Z-Arg-Arg-MCA showed positive and significant correlation with various clinical parameters. Immunoblotting analysis revealed that the molecular form was a 29 kDa mature enzyme. More than 95% of Z-Arg-Arg-MCA hydrolytic activity in each GCF sample was inhibited by CA-074, specific inhibitor of cathepsin B. These results strongly suggested that the gross amount of cathepsin B in GCF as well as its activity level is closely associated with the severity of the disease and that cathepsins B play an important role in the pathogenesis of periodontitis.accepted by W. B. van den Berg     

Effects of noradrenaline and flow on lactate uptake in the perfused rat hindlimb

Skeletal muscle can release or take up lactate depending on the lactate concentration gradient across the cell membrane. In the perfused rat hindlimb without arterial lactate, both noradrenaline (NA) infusion and increased flow promote lactate release and oxygen consumption (VO ₂). However, it is unclear whether NA or increased flow rate have similar effects on lactate uptake. The present study compares these effects in the rat hindlimb perfused at a basal flow rate of 0.33 mL min^?1 g^?1 and 25 °C in the presence of added arterial lactate. When 10 mmol L^?1 L-(+)-lactate was added to the arterial perfusate, lactate was taken up (16 ± 1.0 μmol g^?1 h^?1, n = 13) by the hindlimb with a 35% higher VO ₂ than that without added lactate. Doubling perfusion flow rate enhanced lactate uptake and VO ₂ by 120% and 40%, respectively. Glucose uptake was also increased (by 253%) with increased flow. Infusion of NA increased perfusion pressure, VO ₂ and glucose uptake similarly to those induced by increased flow rate. However, lactate uptake was inhibited by NA. This inhibition was not altered by the β-adrenergic antagonist propranolol. Vasopressin also showed similar effects to NA to decrease lactate uptake associated with increased VO ₂ and vasoconstriction. These data indicate that in the presence of a high arterial lactate concentration, NA has opposite effects from increased flow rate on skeletal muscle lactate uptake although both have similar effects on lactate release in the absence of arterial lactate. Inhibition of lactate uptake may relate to the vasoconstrictive action of NA.     

耳蜗缺血的动物实验模型

应用静脉注射三磷酸腺苷及双侧颈总动脉、单侧椎动脉阻断造成不同程度的豚鼠耳蜗供血下降的实验模型，并应用活体动物耳蜗微循环的研究方法，观察了豚鼠耳蜗微循环的改变。发现此方法可以造成不同程度的耳蜗血流下降，是研究耳蜗微循环与听功能关系的一种有效方法。     

Metabolic control of large-bore arterial resistance vessels,arterioles, and veins in cat skeletal muscle during exercise

The metabolic control of the vascular bed in cat gastrocnemius muscle during exercise was studied with a new technique (Björnberg et al. 1988) permitting continuous and simultaneous recordings of arteriolar and capillary pressures, and of resistances in the following consecutive vascular section: proximal arterial resistance vessels > 25 μm, arterioles < 25 μm, and on the venous side. The study thereby provided quantitative data for resistance and active intrinsic tone in these vascular segments at rest, during graded exercise vasodilatation, and in the post-exercise period. Slight activation of the metabolic control system by low-frequency somatomotor nerve stimulation (light exercise') caused inhibition of intrinsic tone and decreased vascular resistance selectively in the arteriolar section. At increasing workloads, arteriolar resistance was further decreased, but resistance and tone in the proximal arterial resistance vessels and the veins then became clearly reduced as well. This difference in effectiveness of the metabolic control system on the different segments of the vascular bed was expressed quantitatively in terms of a ‘metabolic vasodilator index’. Graded activation of the metabolic control system led to a marked segmental redistribution of intrinsic vascular tone, in turn resulting in an increased pressure drop across the proximal arterial vessels and the veins and a decreased pressure drop over the arterioles. The observed decrease in the pre- to post-capillary resistance ratio caused, at a constant arterial pressure of 100 mmHg, a graded increase in capillary pressure with increasing workloads, at maximum vasodilatation by an average value of 14 mmHg above the resting control value of 15.4 ± 0.6 mmHg. In the post-exercise period, recovery of vascular tone to control was more rapid in the proximal arterial resistance vessels and the veins than in the arteriolar segment.     

Myocardial tissue motion influence on laser Doppler perfusion monitoring using tissue Doppler imaging

Tissue motion of the beating heart generates large movement artifacts in the laser Doppler perfusion monitoring (LDPM) signal. The aim of the study was to use tissue Doppler imaging (TDI) to localise intervals during the cardiac cycle where the influence of movement artifacts on the LDPM signal is minimum. TDI velocities and LDPM signals were investigated on three calves, for normal heartbeat and during occlusion of the left anterior descending coronary artery. Intervals of low tissue velocity (TDI_int<1 cm s⁻¹) during the cardiac cycle were identified. During occlusion, these intervals were compared with low LDPM signal intervals (LDPM_int<50% compared with baseline). Low-velocity intervals were found in late systole (normal and occlusion) and late diastole (normal). Systolic intervals were longer and less sensitive to heart rate variation compared with diastolic ones. The overlap between LDPM_int and TDI_int in relation to TDI_int length was 84±27% (n=14). The LDPM signal was significantly (p<0.001, n=14) lower during occlusion if calculated during minimum tissue motion inside TDI_int), compared with averaging over the entire cardiac cycle without taking tissue motion into consideration. In conclusion, movement artifacts are reduced if the LDPM signal is correlated to the ECG and investigated during minimum wall motion. The optimum interval depends on the application; late systole and late diastole can be used.     

NO在肝纤维化形成中对肝脏微循环的影响

目的探讨外源性一氧化氮(nitric oxide,NO)对肝脏微循环障碍的影响和在肝纤维化发生发展中的作用.方法将大鼠分为3组:正常对照组(normal control,NC):以正常饮食喂养;采用复合因素致肝纤维化组(hepaticfibrosis,HF):同时用生理盐水1.5ml·只-1·d-1灌胃;HF Arg组:以肝纤维化对照组为基础,同时予L-精氨酸(L-arginine,L-Arg)100mg·Kg-1·d-1灌胃.于实验4周末,观察血浆内毒素(lipopolysaccaride,LPS)、NO、丙二醛(malondialdehyde,MDA)和超氧化物歧化酶(superoxide dismutase,SOD)水平,观察各组肝组织纤维增生程度,用台盼蓝原位灌流肝脏来观察肝脏微循环的改变.结果血浆内毒素水平在HF组均明显高于NC组,HF Arg组内毒素水平虽比NC组高,但差异无显著性;NO水平HF Arg组明显高于HF组;血浆MDA水平各实验组均明显高于NC组;血浆SOD活性HF组明显低于NC组和HF Arg组;肝脏纤维组织目标面积HF组明显大于HF Arg组;用台盼蓝原位灌流肝脏发现HF组灌流时间最长,HF Arg组与NC组比较差异无显著性.结论外源性NO可能通过改善肝脏微循环,防止肝脏缺血和炎性细胞介质诱导的氧化损伤,延缓肝纤维化的发展.     

桂蜡膏对老年糖尿病微血管病变患者甲襞微循环的影响

目的:观察桂蜡膏足底穴位贴敷对老年2型糖尿病(T2DM)微血管病变患者甲襞微循环的影响。方法:选择老年T2DM微血管病变患者50例,予以桂蜡膏足底穴位贴敷,每天一次,连续4周为一疗程。治疗前后行甲襞微循环及血液流变性检查。结果:全部病例治疗后与治疗前比较甲襞微循环及血液流变学指标均有不同程度好转,差异具有非常显著性意义(P<0.01)。结论:桂蜡膏足底穴位贴敷治疗可明显改善老年T2DM微血管病变患者甲襞微循环。     

血管活性药物及中药麝香对内毒素性休克的影响及其在抗休克治疗中的作用

目的 :观察缩、扩血管西药及中药麝香对低排高阻型内毒素性休克的影响 ,评价其在抗休克治疗中的疗效。方法 :大鼠随机分为对照组 (A组 )、山莨菪碱组 (B组 )、去甲肾上腺素组 (C组 )、麝香组 (D组 )。颈外静脉推注脂多糖 (LPS)复制内毒素休克模型 ,实验组分别给予山莨菪碱、去甲肾上腺素、麝香药物后观察肠系膜微循环、血压变化。结果 :推注LPS后对照组及实验组动物均发生内毒素性休克 ,出现微循环障碍。山莨菪碱能提高休克后血流速度 ,但A、C、D组微循环未出现明显改善。结论 :山莨菪碱可改善内毒素性休克的微循环瘀滞状态 ,而去甲肾上腺素 ,麝香没有明显作用。