Diurnal variations of plasma testosterone in men

Plasma testosterone (T) levels were assayed by a Competitive Protein Binding (CPB) technique in a group of 31 healthy males. In 22 subjects a single blood sample was taken between 8:00 and 9:00 A.M. and the mean T concentration was 6.84 ± 2.11 ng/ml. In the other 9 normal men, blood samples were taken every 4 hours. The existence of temporal variations for testosterone was confirmed by finding the highest mean plasma levels at 4:00 A.M. (9.28 ± 1.17 ng/ml) and lowest mean levels at 8:00 P.M. (2.66 ± 0.52 ng/ml).     

Relationships between hemorheology, erythrocyte metabolism, and von willebrand factor in athletes and patients with peripheral arterial disease

The relationship between hemorheology, erythrocyte ATP and 2,3-diphosphoglycerate (2,3-DPG) concentrations, and von Willebrand factor antigen was studied in athletes and peripheral arterial disease patients. Lower blood viscosity, mainly due to a higher erythrocyte deformability, was found in athletes compared to control subjects. Higher 2,3-DPG/Ht levels in athletes were correlated with blood viscosity, erythrocyte deformability, the rigidity index, and erythrocyte suspension viscosity at low shear stress. It is suggested that these relationships might be determined by the predominance of immature erythrocytes in the blood circulation of the athletes. In the group of patients, a decrease in ATP/Ht was related to increased erythrocyte aggregation and a higher erythrocyte suspension viscosity. Moreover, the concentration of von Willebrand factor was positively correlated with the erythrocyte aggregation index, erythrocyte suspension viscosity, and plasma viscosity. The results show that alterations in erythrocyte and plasma rheology may be involved in the modification of the functional state of the vascular endothelium and the development of atherosclerosis.     

Polymorphism (353)R>Q of gene of blood clotting factor VII and plasma hemostasis

A comparative estimation was conducted to assess the prevalence of genotypes and alleles of the R>Q(353) polymorphism of the coagulation factor FVII gene between a group of the Russian adolescents with essential arterial hypertension and a group of Russian adolescents without such health problems. The RR genotype was diagnosed in 55 adolescents (75.34%) of the control group and in 99 adolescents (84.61%) of the adolescents suffering from essential arterial hypertension (χ² = 1.949, p = 0.163). The R allele frequency was, respectively, 85.62 and 91.88% (χ² = 3.110, p = 0.078). The role of the FVII gene in the determination of the F7 plasma activity was defined in adolescents with essential arterial hypertension and holders of different alleles. Holders of the R allele had significantly higher activity of coagulation factor F7 (97.66 ± 15.48 against 83.37 ± 15.16, p = 0.002), factor F2 (107.45 ± 6.03 against 103.75 ± 6.81, p = 0.023), and antithrombin III (104.47 ± 15.54% against 95.87 ± 11.30%, p = 0.024). than holders of the Q allele. This relationship was not found in adolescents of the control group.     

Does malnutrition in utero determine diabetes and coronary heart disease in adulthood? Results from the Leningrad siege study,a cross sectional study.

OBJECTIVE: To investigate the relation between decreased maternal food intake and risk factors for coronary heart disease in adult life. DESIGN: Cross sectional study. SUBJECTS: 169 subjects exposed to malnutrition in utero (intrauterine group) during the siege of Leningrad (now St Petersburg) in 1941-4; 192 subjects born in Leningrad just before rationing began, before the siege (infant group); and 188 subjects born concurrently with the first two groups but outside the area of the siege (unexposed group). SETTING: Ott Institute of Obstetrics and Gynaecology, St Petersburg. MAIN OUTCOME MEASURES: Development of risk factors for coronary heart disease and diabetes mellitus-obesity, blood pressure, glucose tolerance, insulin concentrations, lipids, albumin excretion rate, and clotting factors. RESULTS: There was no difference between the subjects exposed to starvation in utero and those starved during infant life in: (a) glucose tolerance (mean fasting glucose: intrauterine group 5.2 (95% confidence interval 5.1 to 5.3), infant group 5.3 (5.1 to 5.5), P = 0.94; mean 2 hour glucose: intrauterine group 6.1 (5.8 to 6.4), infant group 6.0 (5.7 to 6.3), P = 0.99); (b) insulin concentration; (c) blood pressure; (d) lipid concentration; or (e) coagulation factors. Concentrations of von Willebrand factor were raised in the intrauterine group (156.5 (79.1 to 309.5)) compared with the infant group (127.6 (63.9 to 254.8); P < 0.001), and female subjects in the intrauterine group had a stronger interaction between obesity and both systolic (P = 0.01) and diastolic (P = 0.04) blood pressure than in the infant group. Short adult stature was associated with raised concentrations of glucose and insulin 2 hours after a glucose load-independently of siege exposure. Subjects in the unexposed group had non-systematic differences in subscapular to triceps skinfold ratio, diastolic blood pressure, and clotting factors compared with the exposed groups. CONCLUSIONS: Intrauterine malnutrition was not associated with glucose intolerance, dyslipidaemia, hypertension, or cardiovascular disease in adulthood. Subjects exposed to malnutrition showed evidence of endothelial dysfunction and a stronger influence of obesity on blood pressure.     

Effects of Scrambling trumpet Creeper flavone on transient cerebral ischemia model (TIA) in rats

To investigate the effects of Scrambling Trumpet Creeper flavone on neurological function score, brain tissue lesion and related biochemical indexes in rat TIA model. Methods: TIA model was induced by tail vein injection of t-butanol (t-BHP). The rats in each administration group were given large, medium and low dose of Scrambling Trumpet Creeper flavone 0.1% CMC suspension, nimodipine and Yangxueqingnao particles group 0.1% CMC suspension, model group and blank group fed the same volume 0.1% CMC. Once a day, continuous administration of 7d. On the 3rd and 6th day after administration, t-BHP was injected into the tail vein, and then placed in a sealed 1?L?jar. After 10?min of hypoxia, the neurological function score (NDS) was performed. After the first 2 days of TIA administration, the hem rheology was measured immediately after 1?h of administration, and blood rheology was measured immediately after the administration of blood, blood clotting, hematocrit, hematocrit and whole blood viscosity. After HE is staining to observe the pathological changes of hippocampus and cortex in the left-brain tissue. (LDH) and adenosine triphosphate (ATP) were measured. The right brain tissue of the cerebral cortex was observed. The expression of lactate (LD), lactate dehydrogenase (LDH) Fibroblast growth factor (FGF) and insulin growth factor (IGF) were detected by immunohistochemistry.

Determinants of erythropoietin release in response to short-term hypobaric hypoxia.

We measured blood erythropoietin (EPO) concentration, arterial O(2) saturation (Sa(O(2))), and urine PO(2) in 48 subjects (32 men and 16 women) at sea level and after 6 and 24 h at simulated altitudes of 1,780, 2,085, 2,454, and 2,800 m. Renal blood flow (Doppler) and Hb were determined at sea level and after 6 h at each altitude (n = 24) to calculate renal O(2) delivery. EPO increased significantly after 6 h at all altitudes and continued to increase after 24 h at 2,454 and 2,800 m, although not at 1,780 or 2,085 m. The increase in EPO varied markedly among individuals, ranging from -41 to 400% after 24 h at 2,800 m. Similar to EPO, urine PO(2) decreased after 6 h at all altitudes and returned to baseline by 24 h at the two lowest altitudes but remained decreased at the two highest altitudes. Urine PO(2) was closely related to EPO via a curvilinear relationship (r(2) = 0.99), although also with prominent individual variability. Renal blood flow remained unchanged at all altitudes. Sa(O(2)) decreased slightly after 6 h at the lowest altitudes but decreased more prominently at the highest altitudes. There were only modest, albeit statistically significant, relationships between EPO and Sa(O(2)) (r = 0.41, P < 0.05) and no significant relationship with renal O(2) delivery. These data suggest that 1) the altitude-induced increase in EPO is "dose" dependent: altitudes > or =2,100-2,500 m appear to be a threshold for stimulating sustained EPO release in most subjects; 2) short-term acclimatization may restore renal tissue oxygenation and restrain the rise in EPO at the lowest altitudes; and 3) there is marked individual variability in the erythropoietic response to altitude that is only partially explained by "upstream" physiological factors such as those reflecting O(2) delivery to EPO-producing tissues.     

Determinants of arterial stiffness in COPD

Background

Cardiovascular morbidity and mortality is high in patients with chronic obstructive pulmonary disease (COPD) and arterial stiffness is a potentially modifiable risk factor with added predictive value beyond that obtained from traditional risk factors. Arterial stiffness has been the target of pharmacologic and exercise interventions in patients with COPD, but the effects appear limited to those patients with more significant elevations in arterial stiffness. We aimed to identify predictors of increased arterial stiffness in a cohort with moderate to severe COPD.

Methods

Aortic pulse wave velocity (aPWV) was measured in subjects with moderate to severe COPD enrolled in a multicenter randomized controlled trial. Subjects were categorized into quartiles based on aPWV values and factors affecting high arterial stiffness were assessed. Multivariate models were created to identify independent predictors of high aPWV, and cardiovascular disease (CVD).

Results

153 patients were included. Mean age was 63.2 (SD 8.2) years and mean FEV₁ was 55.4 (SD 15.2) % predicted. Compared to the quartile with the lowest aPWV, subjects in the highest quartile were older, had higher systolic blood pressure (SBP), were more likely to be current smokers, and had greater burden of thoracic aortic calcification. On multivariate analyses, age (adjusted OR 1.14, 95%CI 1.05 to 1.25, p?=?0.003) and SBP (adjusted OR 1.06, 95% CI 1.02 to 1.09, p?=?0.001) were independent predictors of elevated aPWV. Body mass index, therapy with cholesterol lowering medications and coronary calcification were independent predictors of CVD.

Conclusions

Elevated arterial stiffness in patients with COPD can be predicted using age, blood pressure and thoracic aortic calcification. This will help identify subjects for enrollment in clinical trials using aPWV for assessing the impact of COPD therapies on CV outcomes.

Trial registration

Clinicaltrials.gov NCT00857766     

In vitro propagation of Asparagus maritimus – A rare Mediterranean salt-resistant species

Asparagus maritimus L. Miller is a rare species growing of the Mediterranean region and is morphologically similar to A. officinalis. In order to establish an efficient in vitro propagation protocol, explants were excised from spear segments and cultured on Murashige and Skoog (1962) medium containing 3% sucrose and various concentrations of growth regulators. The best shoot initiation (3–4 per explant) was achieved on a medium containing 0.88 M N⁶-benzyladenine (BA), 0.93 M kinetin, 1.07 M -naphthaleneacetic acid (NAA) and 3.90 M ancymidol. Shoot initiation could also be achieved without ancymidol but the shoots were thinner and longer. A very high shoot multiplication rate was achieved on media supplemented with 3% sucrose, 1.07 M NAA, 0.93 M kinetin, 0.44 M BA and various concentrations of ancymidol. The lowest concentration of ancymidol (0.39 M) significantly promoted the highest shoot multiplication rate (11.9 shoots/crown). For root formation, media were supplemented with 6% sucrose, 1.07 M NAA and various concentrations of ancymidol. Rooting frequency increased with higher ancymidol concentration up to 5.07 M (82.0% rooting). The number of ex vitro shoots formed was strongly correlated (r=0.66) with the length of roots formed in vitro, which was the highest at a 1.95 M ancymidol.     

Factor VIII and factor IX in a twin population. Evidence for a major effect of ABO locus on factor VIII level.

In order to establish the relative importance of genetic factors on the variation in plasma concentration of coagulation factors VIII and IX, these parameters were determined in 74 monozygotic and 84 like-sexed dizygotic twin pairs. The twins belonged to two age groups: 33-39 years and 57-62 years. Factor VIII was determined as factor VIII coagulant antigen (VIIICAg) and as factor VIII-related antigen (VIIIRAg). Factor IX was determined as factor IX antigen (IXAg). A higher value for each coagulation factor was found in the older-age group compared to the younger group, whereas no difference was found between the sexes. A significant correlation was found between values for VIIIRAg and VIIICAg (r = .56). For VIIICAg, it could be demonstrated that the age effect was secondary to the age effect on VIIIRAg. The concentration of VIIICAg and VIIIRAg varied among ABO blood types, being lowest in type O individuals, higher in A2 individuals, and highest in A1 and B individuals. The effect of the ABO locus on VIIICAg was secondary to an effect on VIIIRAg. Analysis of variance revealed a significant genetic influence on the variance of VIIICAg and VIIIRAg with a heritability estimate of .57 for VIIICAg and .66 for VIIIRAg. This is in agreement with a previous hypothesis of an effect of several autosomal genes on factor VIII concentration. Thirty percent of the genetic variance of VIIIRAg was due to the effect of ABO blood type. The ABO locus is therefore a major locus for the determination of factor VIII concentration. No significant genetic effect on the variation in plasma concentration of IXAg could be detected.     

Deficiency of mast cells in coronary artery endarterectomy of male patients with type 2 diabetes

Background

Increased fasting plasma glucose (FPG), which includes impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and diabetes, is a risk factor for arterial stiffness. While IFG is widely accepted as a cardiovascular risk factor, recent studies have argued that subjects with high-normal glucose level were characterized by a high incidence of cardiovascular disease. The purpose of this study is to investigate the relationship between FPG and arterial stiffness in non-diabetic healthy subjects.

Methods

We recruited 697 subjects who visited the health promotion center of a university hospital from May 2007 to August 2008. Age, sex, body mass index (BMI), resting heart rate, smoking habits, alcohol intake, exercise, blood pressure, medical history, FPG, lipid profile, high sensitivity C-reactive protein (hs-CRP), and Brachial-ankle pulse wave velocity (ba-PWV) were measured. We performed correlation and multiple linear regression analyses to divide the research subjects into quartiles: Q1(n = 172), 65 mg/dL ≤FPG < 84 mg/dL; Q2(n = 188), 84 mg/dL ≤FPG < 91 mg/dl; Q3(n = 199), 91 mg/dL ≤FPG < 100 mg/dL; Q4(n = 138), 100 mg/dL ≤FPG < 126 mg/dL.

Results

FPG has an independent, positive association with ba-PWV in non-diabetic subjects after correcting for confounding variables, including age, sex, BMI, blood pressure, resting heart rate, hs-CRP, lipid profile, and behavioral habits. The mean ba-PWV of the high-normal glucose group (Q3, 1384 cm/s) was higher than that of the low-normal glucose group (1303 ± 196 cm/s vs.1328 ± 167 cm/s, P < 0.05). The mean ba-PWV value in the IFG group (1469 ± 220 cm/s) was higher than that in the normoglycemic group (P < 0.05, respectively).

Conclusions

An increase in FPG, even within the normal range, was associated with aggravated arterial stiffness. Further research is needed to determine the glycemic target value for the prevention of arterial stiffness in clinical and public health settings.     

Socioeconomic gradient in morbidity and mortality in people with diabetes: cohort study findings from the Whitehall Study and the WHO Multinational Study of Vascular Disease in Diabetes.

OBJECTIVE: To assess whether the inverse socioeconomic mortality gradient observed in the general population persists in diabetic people. DESIGN: The Whitehall cohort study and the London cohort of the WHO multinational study of vascular disease in diabetes. SETTING: London. SUBJECTS: 17,264 male civil servants (17,046 without diabetes, 218 with diabetes) aged 40-64 examined in 1967-9, and 300 people with diabetes aged 35-55 from London clinics examined in 1975-7. Both cohorts were followed up until January 1995. MAIN OUTCOME MEASURES: Mortality from all causes, cardiovascular disease, and ischaemic heart disease. RESULTS: In both cohorts people in the lower social groups were older, had higher blood pressure, and were more likely to smoke. In the Whitehall study, the prevalence of heart disease was higher in the lowest social group compared with the highest group, by 6% among non-diabetic people (P = 0.0001) and by 14% among diabetic subjects (P = 0.02). In the WHO study proteinuria was more common in the lowest social group compared with the highest (27% v 15%, P = 0.01), as was retinopathy (54% v 48%, P = 0.5). There was a clear socioeconomic gradient in all cause mortality in both cohorts, with death rates being about twice as high in the lowest compared with the highest social groups. In the Whitehall study this gradient was similar in both diabetic and non-diabetic subjects, and it persisted for mortality from cardiovascular disease and from ischaemic heart disease. About half of the increased risk of death in the lowest social group was accounted for by blood pressure and smoking. CONCLUSIONS: We confirm the existence of an inverse socioeconomic mortality gradient in diabetic people and suggest that this is largely due to conventional cardiovascular risk factors.     

血栓弹力图指导食管癌患者临床输血的价值及其与常规凝血实验检测指标的相关性分析

目的:探讨血栓弹力图(TEG)指导食管癌患者临床输血的价值及其与常规凝血实验检测指标的相关性。方法:选取2017年1月-2019年3月在我院收治的食管癌手术治疗需输血的99例患者作为研究对象,将99例患者随机分为常规凝血功能检测组和TEG组,常规凝血功能检测组采用常规凝血实验检查结果指导输血,TEG组采用TEG检查结果指导输血,对比两组输血前后的常规凝血实验检测指标以及临床用血量,对比TEG组输血前后的TEG指标,分析TEG指标与常规凝血实验检测指标的相关性。结果:两组患者输血前凝血四项和血小板计数(PLT)差异无统计学意义(P>0.05),输血后两组活化凝血酶时间(APTT)、凝血酶原时间(PT)、凝血酶时间(TT)、纤维蛋白原(FIB)均有不同程度的改善(P<0.05),TEG组PT、TT较常规凝血功能检测组低(P<0.05);输血后,TEG组患者凝血反应时间(R值)、血凝块形成时间(K值)较输血前降低,最大血凝块强度(MA值)、凝血综合指数(CI值)升高,凝血形成速率(Angle角)增大,差异有统计学意义(P<0.05);Pearson相关性分析结果显示,R值与APTT呈正相关(P<0.05),K值与PLT呈负相关,与FIB呈正相关(P<0.05),Angle角、MA值、CI值与FIB、PLT呈正相关(P<0.05);TEG组新鲜冰冻血浆、冷沉淀输注量少于常规凝血功能检测组,差异有统计学意义(P<0.05)。结论:TEG能更好地指导食管癌手术患者各种血液成分的合理输注,有效改善凝血异常情况,减少输血用量,TEG指标与常规凝血实验检测指标存在一定的相关性。     

The level of major proteins and minerals in the blood serum of chickens fed diets with pure cellulose

The aim of the research was to determine the concentration of total protein and its fractions as well as the concentration of selected mineral components in the blood serum of male broiler chickens Cobb 500 fed diets with different cellulose content. Blood samples were collected for examination from the birds' pterygoid canal veins on their 42 day of age. There was no influence of cellulose preparation on the content of total protein and its fractions: albumins, alfa1-, alfa2-, beta-, gamma-globulins, albumin to globulin ratio, inorganic phosphorus, sodium, potassium, chloride and iron concentrations in blood serum. The highest calcium concentration (P < 0.05) was detected in the blood serum of males fed a diet with the highest cellulose content (0.75-0.95%). Simultaneously, a tendency of increased calcium content was observed along with an increased amount of pure cellulose in diets. The lowest magnesium level (P < 0.05) was observed in the blood of birds fed diets with the lowest amount of cellulose (0.25-0.45%). The magnesium level in the blood of birds fed a diet with higher amounts of cellulose did not considerably differ from the control group. Results from the current study suggest that introduction of a limited amount of pure cellulose into the diet of broiler chickens does not affect total protein concentration and protein fractions but can influence the mineral content in the blood serum.     

Coagulation factor IXa: the relaxed conformation of Tyr99 blocks substrate binding.

BACKGROUND: Among the S1 family of serine proteinases, the blood coagulation factor IXa (fIXa) is uniquely inefficient against synthetic peptide substrates. Mutagenesis studies show that a loop of residues at the S2-S4 substrate-binding cleft (the 99-loop) contributes to the low efficiency. The crystal structure of porcine fIXa in complex with the inhibitor D-Phe-Pro-Arg-chloromethylketone (PPACK) was unable to directly clarify the role of the 99-loop, as the doubly covalent inhibitor induced an active conformation of fIXa. RESULTS: The crystal structure of a recombinant two-domain construct of human fIXa in complex with p-aminobenzamidine shows that the Tyr99 sidechain adopts an atypical conformation in the absence of substrate interactions. In this conformation, the hydroxyl group occupies the volume corresponding to the mainchain of a canonically bound substrate P2 residue. To accommodate substrate binding, Tyr99 must adopt a higher energy conformation that creates the S2 pocket and restricts the S4 pocket, as in fIXa-PPACK. The energy cost may contribute significantly to the poor K(M) values of fIXa for chromogenic substrates. In homologs, such as factor Xa and tissue plasminogen activator, the different conformation of the 99-loop leaves Tyr99 in low-energy conformations in both bound and unbound states. CONCLUSIONS: Molecular recognition of substrates by fIXa seems to be determined by the action of the 99-loop on Tyr99. This is in contrast to other coagulation enzymes where, in general, the chemical nature of residue 99 determines molecular recognition in S2 and S3-S4. This dominant role on substrate interaction suggests that the 99-loop may be rearranged in the physiological fX activation complex of fIXa, fVIIIa, and fX.     

Alginate plasma expander maintains perfusion and plasma viscosity during extreme hemodilution

Extreme hemodilution was performed in the hamster chamber window model using 6% Dextran 70, lowering systemic hematocrit by 60%. Animals were subsequently divided into three groups and hemodiluted to a hematocrit of 11% using 6% Dextran 70, 6% Dextran 500, and a 4% Dextran 70 + 0.7% alginate solution (n = 6 each group). Final plasma viscosities were 1.4 +/- 0.2, 2.2 +/- 0.1, and 2.7 +/- 0.2 cp, respectively, (P < 0.05, high viscosity vs. low viscosity). Blood viscosities were 2.1 +/- 0.2, 2.9 +/- 0.4, and 3.9 +/- 0.3 cp, respectively. The lowest blood and plasma viscosity group had a significantly lower functional capillary density, 37 +/- 16%, whereas the two high-viscosity solutions were 71 +/- 15% and 76 +/- 12% (P < 0.05, high viscosity vs. low viscosity), respectively. Arteriolar and venular flow in the Dextran 500 and alginate groups was higher than baseline (i.e., normal nontreated animals), whereas the low-viscosity group showed a reduction in flow. These microvascular changes were paralleled by changes in base excess, which was negative for the Dextran 70 group and positive for the other groups. However, tissue Po(2) was uniformly low for all groups (average of 1.4 mmHg). Calculation of tissue oxygen consumption in the window chamber based on the microvascular data, flow, and intravascular Po(2) showed that only the alginate + Dextran 70 solution-exchanged animals returned to baseline oxygen consumption, whereas the other groups were lower than baseline (P < 0.05). These results show that hemodilution performed with high-viscosity plasma expanders yields systemic arterial pressures and functional capillary densities that are significantly higher (P < 0.05) than those obtained with 6% Dextran 70, a fluid whose viscosity is similar to that of plasma. A condition for obtaining these results is that the oncotic pressure of the plasma expander be titrated to near normal, so that autotransfusion of fluid from the tissue into the vascular compartment does not reduce the effects of increasing plasma viscosity and increased shear stress on the microvascular wall.     

Reduced Mucosal Associated Invariant T-Cells Are Associated with Increased Disease Severity and Pseudomonas aeruginosa Infection in Cystic Fibrosis

Background

Primary defects in host immune responses have been hypothesised to contribute towards an inability of subjects with cystic fibrosis (CF) to effectively clear pulmonary infections. Innate T-lymphocytes provide rapid pathogen-specific responses prior to the development of classical MHC class I and II restricted T-cell responses and are essential to the initial control of pulmonary infection. We aimed to examine the relationship between peripheral blood lymphocyte phenotype and clinical outcomes in adults with CF.

Methods

We studied 41 subjects with CF and 22, age matched, non-smoking healthy control subjects. Lymphocytes were extracted from peripheral blood samples and phenotyped by flow-cytometry. Lymphocyte phenotype was correlated with sputum microbiology and clinical parameters.

Results

In comparison to healthy control subjects, mucosal associated invariant T (MAIT)-lymphocytes were significantly reduced in the peripheral blood of subjects with CF (1.1% versus 2.0% of T-lymphocytes, P = 0.002). MAIT cell concentration was lowest in CF subjects infected with P. aeruginosa and in subjects receiving treatment for a pulmonary exacerbation. Furthermore a reduced MAIT cell concentration correlated with severity of lung disease.

Conclusion

Reduced numbers of MAIT cells in subjects with CF were associated with P. aeruginosa pulmonary infection, pulmonary exacerbations and more severe lung disease. These findings provide the impetus for future studies examining the utility of MAIT cells in immunotherapies and vaccine development. Longitudinal studies of MAIT cells as biomarkers of CF pulmonary infection are awaited.     

缺氧对右心室最大心肌血流量的影响

为了探讨缺氧对冠状血管贮备力的影响,我们观察了缺氧时大鼠血流动力学及右心室最大心肌血流量的变化。结果表明,急性缺氧引起ＰａＯ２、心输出量及氧运送量降低,但右心室心肌血流量增加,右心室最大与安静血流量比值降低。慢性缺氧时ＰａＯ２降低,血球比积和右心室重量指数增加,氧运送量和右心室血流量正常,但最大血流量降低,小动脉增厚、外膜胶元增加。以上结果提示,慢性缺氧对冠状血管贮备减少可能是小动脉壁增厚、外膜胶元增加和血液粘滞性增加及右心室肥大的结果。     

Beta-adrenergic modulation of pulmonary transvascular fluid and protein exchange

We determined in anesthetized sheep whether isoproterenol, a beta-adrenergic agonist, prevents the increases in pulmonary fluid and protein exchange produced by thrombin-induced intravascular coagulation. Seven sheep were infused intravenously with 0.05 micrograms X kg-1 X min-1 isoproterenol before infusion of alpha-thrombin, and six sheep were infused with alpha-thrombin only and served as control subjects. The marked increases in pulmonary lymph flow and lymph protein clearance in the control thrombin group were attenuated (P less than 0.05) in the isoproterenol group in association with a higher pulmonary blood flow (P less than 0.05) and a lower pulmonary vascular resistance (P less than 0.05) in the isoproterenol group and with similar increases in pulmonary arterial and pulmonary arterial wedge pressures in both groups. The decreases in fluid and protein fluxes produced by isoproterenol are related to its beta-adrenergic properties because propranolol, a beta-adrenergic antagonist, blocked the protective effects of isoproterenol in a second group of sheep infused with propranolol, isoproterenol, and thrombin. Raising left atrial pressure to test for changes in vascular permeability increased protein flux to a much greater extent in the thrombin control group than in the isoproterenol group challenged with thrombin. The data suggest that isoproterenol attenuated the increase in fluid and protein fluxes produced by thrombin-induced intravascular coagulation by a permeability-decreasing mechanism.     

缺氧对右心室最大心肌心血流量的影响

为了探讨氧对冠状血管贮备方法的影响,我们观察了缺氧对血流动力学及右心室最大心肌血汉量的变化。结果表明,急性缺氧引起的ＰａＯ２、心输出量及氧运送量降低,但右心室心肌血流量增加,右心室最大与安静血流量比值降低,生缺氧时ＰａＯ２降低,血球比积和右心室生理指数增加,氧运送量和右心室血流量正常,但最大血流量降低,小动脉增厚、外胶元增加,以上结果提示,慢性缺氧对冠状血管贮备减少可能是小动脉壁增厚、外胶元增加和     

Peripheral vascular resistance increases after termination of obstructive apneas.

The mechanisms by which obstructive apneas produce intermittent surges in arterial pressure remain poorly defined. To determine whether termination of obstructive apneas produce peripheral vasoconstriction, we assessed forearm blood flow during and after obstructive events in sleeping patients experiencing spontaneous upper airway obstructions. In all subjects, heart rate was monitored with an electrocardiogram and blood pressure was monitored continuously with digital plethysmography. In 10 patients (protocol 1), we used forearm plethysmography to assess forearm blood flow, from which we calculated forearm vascular resistance by performing venous occlusions during and after obstructive episodes. In an additional four subjects, we used simultaneous Doppler and B-mode images of the brachial artery to measure blood velocity and arterial diameter, from which we calculated brachial flow continuously during spontaneous apneas (protocol 2). In protocol 1, forearm vascular resistance increased 71% after apnea termination (29.3 +/- 15.4 to 49.8 +/- 26.5 resistance units, P < 0.05) with all patients showing an increase in resistance. In protocol 2, brachial resistance increased at apnea termination in all subjects (219.8 +/- 22.2 to 358.3 +/- 46.1 mmHg x l(-1) x min; P = 0.01). We conclude that termination of obstructive apneas is associated with peripheral vasoconstriction.