The estimation of microcirculation state in cerebrovascular disorders by data of laser Doppler flowmetry and hemorheological parameters

The study was aimed to evaluate microvascular blood flow and theological blood properties in healthy volunteers (n = 27) and patients with cerebral accident (n = 30). To study cutaneous blood flow we used the multifunctional laser analyzer of blood microcirculation LAKK (LAZMA, Moscow) with spectrophotometric channel and wavelet analysis of blood flow oscillations. Viscosity of the whole blood, plasma, RBC aggregability and deformability were assessed. Results: microcirculation index was by 25% (p < 0.05) lower in patients compared to the control group. Computing amplitude-frequency range of blood flow oscillations revealed notable changes in the blood flow regulation mechanisms under cerebrovascular accident: the amplitudes of all active rhythms (endothelial, neurogenic and myogenic ones) were increased. In spite of such activization of regulatory mechanisms, aimed to keep essential blood supply to tissue, index of specific oxygen consumption by tissue was decreased by 21% (p < 0.05) under cerebrovascular disorders. Blood rheological properties in patients group were impaired compared to the healthy group: blood viscosity was increased because of elevated plasma viscosity, increased RBS aggreagation and decreased erythrocyte deformability. Thus, our results demonstrated the decrease of tissue perfusion, activization of vasodilating mechanisms, impaired blood rheology and the decrease of oxygen supply to tissue in patients with cerebrovascular accident. Statistical analysis revealed a number of significant correlations between the hemorheological parameters and passive rhythms of microcirculation in norm. In patients blood viscosity correlated to the amplitude of active regulatory rhythms (endothelial, neurogenic and myogenic oscillations). Close interralations between rheological and microcirculation parameters testified the important role of hemorheological factors in maintenance of microvascular blood flow and oxygen delivery to tissue.     

Influence of vehicle resistance on transdermal iontophoretic delivery of acetylcholine and sodium nitroprusside in humans.

Iontophoresis is a valuable method of noninvasive drug delivery for assessment of skin microvascular function, but it is important to consider and minimize its potential nonspecific electrical effects on blood flow. The use of sodium chloride (NaCl) instead of water as the iontophoresis vehicle has been reported to reduce these effects because it has a lower electrical resistance. However, this argument may not be valid when an agonist is added to the vehicle because its resistance will be changed. The aim of our study was to determine whether there is a difference in resistance between water and NaCl when used as vehicles for iontophoresis of acetylcholine (ACh) and sodium nitroprusside (SNP). Four cumulative doses of each drug, dissolved in either water or NaCl, were delivered via iontophoresis to the forearm skin of 14 healthy volunteers. We measured the resulting blood flow responses by using laser-Doppler imaging and the voltage across the electrodes for each delivery as an index of resistance. For ACh and SNP, there were no significant differences between the voltages measured when either water or NaCl was used as the vehicle. However, the blood flow responses to both agonists were significantly lower with NaCl (ACh: 25% lower, P < 0.001; SNP: 15% lower, P = 0.019). The use of NaCl is therefore unlikely to decrease any nonspecific electrical effects, and it may in fact reduce the effective dose of drug delivered. Deionized water is a better iontophoresis vehicle for the assessment of microvascular function in skin when using ACh and SNP.     

Parameters of Microcirculation in Both Sexes at Different Ages

We have used laser Doppler flowmetry with wavelet analysis of the amplitude–frequency spectrum of blood flow oscillations to investigate the microcirculation and the mechanisms of its control in both sexes at different ages: junior school age, adolescence, and preadult age. It was shown that adolescents (both boys and girls) had more intense tissue perfusion and root-mean-square deviation of microcirculation as compared with junior school age. We observed an increase in the basal indexes of microcirculation in adolescents, which is caused by the activation of regulatory processes. In preadult girls, the microcirculatory flow index (MFI) was lower compared to adolescent girls; in preadult boys, MFI is higher compared to adolescent boys. It probably results from redistribution of influence between regulatory mechanisms. The analysis of the amplitude–frequency spectrum of preadults shows a decrease in oscillation amplitudes in all active and passive oscillation ranges compared to adolescents. Thus, we have detected the differences in microcirculation parameters and in the effects of active and passive regulatory factors of microcirculation. The findings are indicative of certain age-related changes in the microcirculation system.     

Exogenous zinc improves blood fluidity but has no effect on the mechanisms of vascular response to acetylcholine iontophoresis in humans

Recent findings in cellular signaling function of zinc through the mobilization intracellular calcium or by inducing ATP release suggest that extracellular zinc plays an important role in many physiological functions. However, such an extracellular signaling action of zinc for most cells is not known. Therefore, we investigated whether zinc plays any role in endothe-lium-dependent acetylcholine (ACh)-induced vasodilatation in microvascular beds. Transdermal iontophoresis was used to transport ACh through the forearm skin and cutaneous perfusion was measured using a laser Doppler flowmeter (LDF). Experiments were repeated using (1) zinc instead of ACh to test the effect of zinc ions alone and (2) concomitant iontophoresis of ACh and zinc to explore the effect of zinc on ACh-induced vasodilatation. Although zinc augments blood flow, curve-fitting to LDF signals indicate that zinc has no effect on the neural and endothelial component of ACh-induced vasodilatation. Additionally, no effect of Zn²⁺ on blood flow was found during its iontophoresis alone. Therefore, it is suggested from the Fourier analysis of LDF signals that the Zn⁺ might influence blood fluidity by its action on red blood cells deformability/aggregability during a high-blood-flow condition, which might, in turn, decrease blood viscosity and improve blood flow in vivo.     

Relation between microcirculation parameters and Pc3 geomagnetic pulsations

An individual analysis of long-term monitoring of microcirculation parameters of nine healthy volunteers showed that an increase in the geomagnetic activity led to an increase in tissue perfusion, variability of blood flow and growth of the amplitude of neurogenic and myogenic oscillations in four volunteers. It was found that the degree of microcirculation sensitivity to the level of geomagnetic activity varies with time and is proportional to its average level in the period of measurement. A comparison of frequency ranges of oscillations of blood flow and variations of the geomagnetic activity shows that neurogenic and myogenic oscillations showing the highest sensitivity to the geomagnetic activity have the same frequency as geomagnetic Pc3 pulsations. The pulsations of this frequency range are excited mainly during geomagnetic disturbances, which may explain the correlation between the microcirculation parameters and the K _p-index. The relation of the amplitude-frequency characteristics of Pc3-pulsations can explain the results obtained using Lednev’s model which treats the spins of hydrogen nuclei as a primary target of action for extremely weak alternating magnetic fields.     

Estimation of the microcirculation state in cerebrovascular disorders using laser doppler flowmetry data and hemorheological parameters

The microcirculation state was assessed in the group of patients with ischemic stroke (n = 30) and the control group of healthy individuals (n = 27) using laser Doppler flowmetry and the wavelet analysis of the amplitude-frequency range of microvascular blood flow oscillations combined with absorption spectroscopy. The hemorheological parameters (blood and plasma viscosity, the degree of red blood cell aggregability and deformability) were assessed in both groups, as were their correlations with the microcirculation parameters. Decreased tissue perfusion (by 25%) and specific oxygen consumption (by 21%) were revealed in a cerebrovascular accident. Changes in the tone-forming regulatory mechanisms of microcirculation of vasodilating nature (decreased microvascular tone, activation of the secretory function of endothelium) may be regarded as a compensatory reaction aimed at maintaining the blood supply of organs and tissues in stroke. The blood viscosity increase in patients due to the plasma viscosity increase and increased red blood cell aggregability and their decreased deformability cause the blood flow to slow down and the wall shear stress to increase, which activates the endothelial secretory function and vasodilation of microvessels. Correlation between the rheological parameters and the passive (respiratory and cardiac) rhythm amplitudes was observed in the control group. In patients, the hemorheological parameters were correlated with the characteristics of the active factors of microvascular blood flow modulation (endothelial, neurogenic, and myogenic), which confirms the role of changed blood properties and regulatory tone-forming mechanisms in the maintenance of tissue perfusion in cerbrovascular accidents.     

卵巢早衰患者血清抑制素B、抗苗勒管激素及性激素水平与子宫动脉血流参数的相关性研究

目的:探讨卵巢早衰(POF)患者血清抑制素B(INHB)、抗苗勒管激素(AMH)及性激素水平与子宫动脉血流参数的相关性。方法:选择2018年5月至2020年5月期间我院收治的126例POF患者(POF组)和同期于我院进行体检的85例健康女性志愿者(对照组)。检测所有研究对象血清INHB、AMH以及促黄体生成素(LH)、促卵泡激素(FSH)、雌二醇(E2)水平,经阴道多普勒超声检测子宫动脉血流参数[收缩期峰值流速(PSV)、舒张末期流速(EDV),血流阻力指数(RI)、搏动指数(PI)]。Pearson相关性分析POF患者血清INHB、AMH、LH、FSH、E2水平与PSV、EDV、RI、PI的相关性。结果:POF组血清INHB、AMH、E2水平、PSV、EDV低于对照组(P<0.05),LH、FSH水平、RI、PI高于对照组(P<0.05)。Pearson相关性分析结果显示POF患者血清INHB、AMH、E2水平与PSV、EDV呈正相关(P<0.05),与RI、PI呈负相关(P<0.05),LH、FSH与PSV、EDV呈负相关(P<0.05),与RI、PI呈正相关(P<0.05)。结论:POF患者血清INHB、AMH、E2水平降低,LH、FSH水平升高,血清INHB、AMH和性激素与子宫动脉血流受限有关。     

Effects of desensitization of capsaicin-sensitive afferent neurons on gastric microcirculation in rats depend on the blood glucocorticoid hormone level

The effects of desensitization of capsaicin-sensitive afferent neurons on gastric microcirculation were investigated before and after administration of indomethacin at ulcerogenic dose in adrenalectomized rats with or without corticosterone replacement and in sham-operated animals. We estimated the blood flow velocity in submucosal microvessels; the diameters and permeability of mucosal venous microvessels as parameters of gastric microcirculation. Desensitization of capsaicin-sensitive neurons was performed with capsaicin at the dose 100 mg/kg two weeks before the experiment. Adrenalectomy was created one week before experiment. In vivo microscopy technique for the direct visualization of gastric microcirculation and the analysis of the blood flow was employed. Indomethacin at ulcerogenic dose decreased the blood flow velocity in submucosal microvessels, caused dilatation of superficial mucosal microvessels and increased their permeability. Desensitization of capsaicin-sensitive afferent neurons potentiated indomethacin-induced microvascular disturbances in gastric submucosa-mucosa. These potentiated effects of the desensitization are obviously promoted by concomitant glucocorticoid deficiency. Thus, glucocorticoid hormones have a beneficial effect on gastric microcirculation in rats with desensitization of capsaicin-sensitive afferent neurons.     

同型半胱氨酸、子宫动脉血流参数与反复妊娠丢失患者胰岛素抵抗和妊娠结局的关系

摘要 目的：探讨同型半胱氨酸（Hcy）、子宫动脉血流参数与反复妊娠丢失（RPL）患者胰岛素抵抗和妊娠结局的关系。方法：选择2020年6月至2022年10月昆明市妇幼保健院收治的162例RPL患者作为RPL组和同期82例规律产检的健康孕妇作为对照组。按照妊娠结局将RPL患者分为活产组（85例）和流产组（77例）。检测血清Hcy水平,胰岛素抵抗指数（HOMA-IR）,超声检查子宫动脉血流参数,包括子宫动脉收缩期峰值/舒张末期流速（S/D）、搏动指数（PI）、血流阻力指数（RI）。Pearson相关性分析Hcy、子宫动脉血流参数与HOMA-IR的相关性。采用多因素Logistic回归分析RPL 患者妊娠结局的影响因素。采用受试者工作特征（ROC）曲线分析Hcy、子宫动脉血流参数对RPL 患者妊娠结局的预测价值。结果：RPL组血清Hcy水平,S/D、PI、RI以及HOMA-IR均高于对照组（P＜0.05）。RPL组血清Hcy,S/D、PI、RI与HOMA-IR均呈正相关（P＜0.05）。流产组血清Hcy水平,S/D、PI、RI以及HOMA-IR均高于活产组（P＜0.05）,多因素Logistic回归分析显示高HOMA-IR、高Hcy、高S/D、高RI、染色体异常是RPL患者流产的危险因素（P＜0.05）。ROC曲线分析显示联合Hcy、S/D、RI预测RPL患者流产的曲线下面积（AUC）为0.849,高于单独预测。结论：RPL患者子宫动脉血流参数S/D、RI、PI和血清Hcy水平均增高,高S/D、RI和Hcy与RPL患者胰岛素抵抗以及流产风险增加有关。联合S/D、RI和Hcy可提高RPL流产风险评估效能。     

血清FFA、PLGF、tTG、T-cadherin与早发型子痫前期患者子宫动脉血流参数和围产儿不良结局的关系研究

摘要 目的：探讨血清组织型转谷氨酰胺酶（tTG）、胎盘生长因子（PLGF）、游离脂肪酸（FAA）、T-钙粘蛋白（T-cadherin）与早发型子痫前期（EOPE）患者子宫动脉血流参数的关系,并分析围产儿不良结局的影响因素。方法：选择2019年9月~2021年5月在我院接受治疗的116例EOPE患者作为EOPE组,另选取同期80例来我院例行产检的健康志愿者孕妇作为对照组。对比EOPE组、对照组的血清FFA、PLGF、tTG、T-cadherin水平和子宫动脉血流参数。采用Pearson法分析血清FFA、PLGF、tTG、T-cadherin与EOPE患者子宫动脉血流参数的相关性。采用多因素Logistic回归分析围产儿不良结局的危险因素。结果：EOPE组的血清FFA、tTG高于对照组,PLGF、T-cadherin则低于对照组（P<0.05）。EOPE组的阻力指数（RI）、收缩期和舒张期血流流速比值（S/D）、搏动指数（PI）高于对照组（P<0.05）。Pearson相关性分析结果显示,RI、PI、S/D与FFA、tTG均呈正相关,而与PLGF、T-cadherin均呈负相关（P<0.05）。多因素Logistic回归分析结果显示,白蛋白偏低、丙氨酸氨基转氨酶偏高、血肌酐偏高、FFA偏高、PLGF偏低、tTG偏高、T-cadherin偏低、RI偏高、PI偏高、S/D偏高均是围产儿不良结局的危险因素（P<0.05）。结论：EOPE患者血清中FFA、tTG表达升高,PLGF、T-cadherin表达下降,且与子宫动脉血流参数具有一定的相关性。白蛋白、丙氨酸氨基转氨酶、血肌酐等均是围产儿不良结局的危险因素,应加强对上述指标的监测,尽早进行相关干预,以降低围产儿不良结局的发生率。     

Water-electrolyte metabolism,renal function,and cutaneous microcirculation in human subjects during a seven-day dry immersion

The parameters of renal osmoregulatory and excretory functions, circulating plasma volume, and oxygen transport by erythrocytes have been studied in an experiment with healthy volunteers in a seven-day dry immersion without prophylactic, with individual body weight and caloric demand, water, salt, and calcium consumed with food and beverages taken into account and the temperature conditions of water bath controlled. The functional state of cutaneous microcirculation has been assessed (by the method of laser Doppler iontophoresis in vivo with acetylcholine and nitroprusside). It has been demonstrated that the influence of dry immersion caused an acceleration of the excretion of liquid and electrolytes (sodium) and reduced the volume of circulating plasma (VCP, determined by hematocrit) together with relative hyperhemoglobinemia and hypererythrocitemia at the early stages of immersion. The relative increase in VCP without alteration of the specific hemoglobin concentration was observed during the first week of the rehabilitation period. Immersion resulted in a decrease in the reaction of skin vessels to acetylcholine depending on prostaglandin production by endotheliocytes but did not change NO-dependent vasodilation. Thus, a decrease in physical activity causes dysfunction of endothelium due to a decrease in the influence of the shear stress, which results in the dysfunction of endotheliocytes and, probably, activation of apoptosis.     

The effects of diabetes and aminoguanidine treatment on endothelial function in a primate model of type 1 diabetes

Abnormalities of endothelial function have been demonstrated in diabetes and are thought to play a role in the pathogenesis of diabetic complications. The aims of this study were to determine whether aminoguanidine, an inhibitor of glycation, can prevent endothelial and microcirculation abnormalities in a primate model of type 1 diabetes. Male baboons (Papio hamadryas) were assigned to one of the four groups: control, diabetes, control treated with aminoguanidine or diabetes treated with aminoguanidine. Diabetes was induced by streptozocin (60 mg/kg) and treated with once daily injection of insulin. Aminoguanidine was given subcutaneously (10 mg/kg), once a day. Diabetic animals had a mean duration of diabetes of 8.9 +/- 3.4 years and HbA1c of 8.9 +/- 1.1%. Microvascular function was measured by laser Doppler velocimetry, with examination of endothelium-dependent increase in skin blood flow (SkBF) following iontophoresis of acetylcholine (ACh) and endothelium-independent increase in SkBF in response to the nitric oxide (NO) donor sodium nitroprusside (SNP). Multiple regression analysis identified diabetes (P = 0.049) and aminioguanidine treatment (P = 0.026) as significant determinants of ACh response. The diabetic baboons treated with aminoguanidine had less Ach-mediated SkBF response compared with controls (1.39 +/- 0.32 vs. 2.26 +/- 0.61, F = 3.3, P = 0.04), but there was no difference between groups in SkBF response to SNP. We conclude that endothelial dysfunction can be demonstrated in this primate model of type 1 diabetes at a stage when overt diabetic complications are not present. This occurred in the absence of insulin resistance or significant hypercholesterolemia. Administration of aminoguanidine from the onset of diabetes was not able to prevent this abnormality and in fact aggravated the endothelial response. Effects of aminoguanidine on NO synthase may contribute to this phenomenon.     

Oscillatory processes in lymph microcirculation in the human skin

This study was the first to use laser Doppler flowmetry followed by wavelet analysis in order to estimate oscillations in lymph microcirculation in 30 subjects with (n = 13) or without (n = 17) edema of the distal part of the upper limb. Lymph flow in the human skin exhibited clear dominance of pacemaker phase oscillations in the frequency ranges of 0.021–0.042 and 0.016–0.035 Hz in the skin of the palm surface of the finger nail bone and in the skin of the forearm, respectively. Edema was associated with an increase in the peak frequencies and normalized maximum amplitudes (Al/Ml, where Al is the mean value of the maximum amplitude of phase oscillations, and Ml is the value of the averaged lymph flow expressed in perfusion units). Low-amplitude oscillations were recorded rarer in the myogenic, endothelial, and respiratory ranges. We did not find any cardiac pulse rhythm in the wavelet spectrum of the lymph flow. We did not find any interaction between the Al/Ml value and the skin temperature. In the group of subjects without edema, under physiological conditions only, we found a negative correlation between the Al/Ml value and the amplitudes of myogenous proper blood flow oscillations, which reflected the number of functional capillaries and activity of oxidative metabolism in the tissue. In the group with edema, we did not find any correlations between the indices of lymph flow and blood flow. The values of normalized amplitude and frequency of phase oscillations may be used as efficient diagnostic tools in the studies on lymph microcirculation.     

Blood Circulation Pattern in Highly Skilled Swimmers

Echocardiography was used to study the parameters of cardiodynamics, systemic hemodynamics, left ventricular morphology and functioning, phase analysis of cardiac activity, and rheological blood properties in highly skilled expert swimmers. The relationship between different levels of blood circulation was established. A close correlation between the blood flow at rest and arterial pressure was found to contribute to the optimization of microvascular pressure and shear stress in accordance with body demands.     

Role of gastric microcirculation in the gastroprotection by glucocorticoids released during water-restraint stress in rats

Our previous investigations demonstrated that glucocorticoids released in response to stress protect gastric mucosa against stress-induced ulceration. This study was designed to determine whether gastric microcirculation is involved in the mechanism of gastroprotective glucocorticoid action. For this we evaluated the effects of deficiency of glucocorticoid production during 3 hr water-restraint stress and corticosterone replacement on the stress-induced gastric erosions, gastric microcirculation and arterial pressure in rats. The stress was produced in awake rats and gastric microcirculation and arterial pressure were evaluated in animals anesthetized in 3 hr after the onset of water-restraint stress. An in vivo microscopy technique for the direct visualization of gastric microcirculation was employed. The gastric submucosal and the superficial mucosal microvessels were monitored on television screen through a microscope and the pictures were stored by microfilming for the analysis of red blood cell velocity and vessel diameter. Gastric microcirculation was estimated on the base of both the volume blood flow velocity in submucosal microvessels and the diameter of superficial mucosal venous microvessels. Gastric erosions were quantitated by measuring the area of damage. Plasma corticosterone levels were also measured after 3 hr stress by fluorometry. Water-restraint stress induced an increase in corticosterone level, an appearance of gastric erosions, a decrease in volume blood flow velocity of submucosal microvessels, a dilatation of superficial mucosal microvessels, a decrease in arterial pressure. The deficiency of glucocorticoid production during water-restraint stress promoted the stress-induced gastric ulceration, a dilatation of mucosal microvessels, a decrease of blood flow velocity in submucosal microvessels and of arterial pressure. Corticosterone replacement eliminated the effects of deficiency of glucocorticoid production on all of the parameters under study. Thus, the stress-induced corticosterone rise decreased gastric ulceration, restricted both the reduction of blood flow velocity in submucosal microvessels and a dilatation of superficial mucosal venous microvessels during water-restraint stress. These data suggest that the gastroprotective action of glucocorticoids during stress may be provided by the maintenance of gastric blood flow.     

A rapid response microviscosimeter

An in vitro instrument is described which is designed to measure effective viscosity of blood in arteriolar size tubes at physiologically nominal flow rates, mimicking flow in the microcirculation. The 41-micron microviscosimeter is accurate within 2% when tested against viscosity standards and is reproducible within 2% using blood samples. Because the full-scale instrument response time is 3 s, either fresh or anticoagulated blood samples may be used. Measured over the nominal range of blood flow rate (Q), effective blood viscosity was found to be an increasing, decreasing, or flat function of Q, depending upon the particular individual being tested. A reference group of 81 young, healthy subjects was used to define viscous resistance (VR), a new parameter that provides for quantitative viscosity comparisons between individuals or groups without hematocrit manipulation of blood samples. As examples of the microviscosimeter's use, a group of 118 subjects was used to test for VR variation between various group subsets. No difference in VR was found between men and women; exercisers had lower VR than nonexercisers; and overweight subjects had more viscous blood than non-overweight subjects. The instrument will be useful for in vitro investigations of effective viscosity and viscous resistance in the microcirculation.     

Increased cardiac output and microvascular blood flow during mild hemoconcentration in hamster window model

The effect of small hematocrit (Hct) increases on cardiac index (cardiac output/body wt) and oxygen release to the microcirculation was investigated in the awake hamster window chamber model by means of exchange transfusions of homologous packed red blood cells. Increasing Hct between 8 and 13% from baseline increased cardiac index by 5-31% from baseline (P < 0.05) and significantly lowered systemic blood pressure (P < 0.05). The relationship between Hct and cardiac index is described by a second-order polynomial (R2 = 0.84; P < 0.05) showing that Hct increases up to 20% from baseline increase cardiac index, whereas increases over 20% from baseline decrease cardiac index. Combining this data with measurements of blood pressure allowed to determine total peripheral vascular resistance, which was a minimum at 8-13% Hct increase and was described by a second-order polynomial (R2 = 0.83; P < 0.05). Oxygen measurements in arterioles, venules, and the tissue at 8-13% Hct increase were identical to control; thus, as a consequence of increased flow and oxygen-carrying capacity, oxygen delivery and extraction increased, but the change was not statistically significant. Previous results with the same model showed that the observed effects are related to shear stress-mediated release of nitric oxide, an effect that should be also present in the heart microcirculation, leading to increased blood flow, myocardial oxygen consumption, and contractility. We conclude that a minimum viscosity level is necessary for generating the shear stress required for maintaining normal cardiovascular function.     

Study of dynamic microcirculatory problems in ‘blackfoot disease’ -emphasizing its differences from arteriosclerosis

The cutaneous microcirculation can be divided into thermoregulatory shunt vessels and nutritive skin capillaries. Flux in nonnutritional shunt vessels dominates the signal recorded by the laser Doppler flowmeter. Computerized videophotometric capillaroscopy is a sensitive method for assessing cutaneous nutritive microcirculation. Using patients with blackfoot disease and arteriosclerosis as disease models, we evaluated the sensitivity and clinical usefulness of these relatively new techniques for peripheral vascular disorders. In blackfoot disease, blood flux measured by the laser Doppler flowmeter in the affected toe was lower than that in the nonaffected toe. In symptom-free fingers, blood flow was not significantly different between blackfoot disease and arteriosclerosis. However, blood flow in both diseases was lower than that of the control group. Patients who had the same status of thermoregulatory flow and eyeground arteriosclerotic classification underwent a 1-min arterial occlusion of the digits. The postocclusive reactive hyperemia response (PRH) of nailfold capillary loops was evaluated. All parameters for PRH for the cutaneous nutrient microcirculation including resting capillary blood cell velocity (rCBV), peak capillary blood cell velocity (pCBV) and time to pCBV were more significantly disturbed in the blackfoot disease group than in the arteriosclerotic group. On the basis of the results of this study, dynamic capillaroscopy provides a new approach for the early detection of circulatory disturbances resulting from different mechanisms.     

Ocular blood flow parameters in patients with rhegmatogenous retinal detachment

The aim of the present study is to evaluate the potential statistically significant differences in the ocular blood flow parameters in eyes with rhegmatogenous retinal detachment (RD). Eleven patients, 5 females and 6 males, mean age 46 years (range 22-70), with the unilateral rhegmatogenous RD were enrolled in the study. Colour Doppler Ultrasound was used to measure ocular blood flow velocities in the ophthalmic artery (OA), posterior ciliary's arteries (PCA) and ophthalmic vein (OV). The contralateral eye served as a control. All Doppler examinations were performed 1 day before and exactly 3 days after the retinal detachment surgery. The measurements of the peak systolic velocity (Vmax), diastolic velocity (Vd), minimum velocity (Vmin), time-averaged velocity (TAV), resistive index (RI) and pulsatility index (PI) showed no statistically significant difference (by paired Student's t-test, p > 0.05) between the OA, PCA and OV in healthy eyes and eyes with RD before operation, as well as between the eyes with RD before and after the operation. Only was increased RI in OV of eyes with RD after the surgery (p < 0.05). All these parameters were not related with 2 or more quadrants of RD, but the difference in duration of retinal detachment in days is statistically significant (by Wilcoxon t-test p > 0.05). Pearson correlation method gave statistically significant correlation between RI and PI of the OA in healthy eyes (r = 0.826, p < 0.01), eyes with RD before operation (r = 0.847, p < 0.01) and eyes with RD after the operation (r = 0.856, p < 0.01). Formula for the calculation of PI by RI was derived using linear regression analysis in all three cases. Scleral buckling surgery leaves the ocular blood parameters in OA unchanged. The correlation between RD and logarithm of duration of RD in days is statistically significant.     

Vascular and neural mechanisms of ACh-mediated vasodilation in the forearm cutaneous microcirculation.

The relative contribution of endothelial vasodilating factors to acetylcholine (ACh)-mediated vasodilation in the forearm cutaneous microcirculation is unclear. The aims of this study were to investigate the contributions of prostanoids and cutaneous C fibers to basal cutaneous blood flow (CuBF) and ACh-mediated vasodilation. ACh was iontophoresed into the forearm, and cutaneous perfusion was measured by laser-Doppler flowmetry. To inhibit the production of prostanoids, four doses of acetylsalicylic acid (ASA; 81, 648, 972, and 1,944 mg) were administered orally. Cutaneous nerve fibers were blocked with topical anesthesia. Cyclooxygenase inhibition did not change basal CuBF or endothelium-mediated vasodilation to ACh. In contrast, ASA (972 and 1,944 mg) significantly reduced the C-fiber-mediated axon reflex in a dose-dependent fashion. Blockade of C-fiber function significantly reduced axon reflex-mediated vasodilation but did not affect basal CuBF or endothelium-dependent vasodilation. The findings suggest that prostanoids do not contribute significantly to basal CuBF or endothelium-dependent vasodilation in the forearm microcirculation. In contrast, prostanoids are mediators of the ACh-provoked axon reflex.