Influence of garlic powder on cutaneous microcirculation: a randomised, placebo-controlled, double-blind, crossover study in apparently healthy subjects.
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Biomedical subjects
Publications and source records attributed to C Mrowietz.
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In summary, it can be said that the improvement of blood fluidity and the simultaneous increase in fibrinolytic activity are an ideal complement. While the increase in fibrinolytic activity supports the physiological reparation process in the microcirculation, the improvement of blood fluidity produces an increase in capillary perfusion that has, in some way, a cleaning effect, with a 'purification' of the microcirculation.
In a randomized placebo controlled single-blind cross-over study of n = 10 apparently healthy subjects the influence of Ginkgo biloba (Kaveri) on blood fluidity and cutaneous microcirculation was studied. Microcirculation was measured before and every 30 min for 4 h after administration of Ginkgo biloba; fluidity of blood was determined before and after 1, 2 and 4 h. Significant changes in blood pressure or heart rate were found neither during Ginkgo phase nor placebo phase. Haematocrit, plasma viscosity, erythrocyte rigidity, thrombocyte and leukocyte count as well as thrombocyte aggregation and the number of circulating thrombocyte aggregates were also not influenced by the Ginkgo nor the placebo solution. In contrast a remarkable influence on the erythrocyte aggregation was observed: comparing two samples a significant decrease by 15.6% (p less than 0.001) with regard to the initial value was observed after 2 h. The blood flow in the nail fold capillaries also increased significantly by about 57% (p less than 0.004) 1 h after administration.
In an open study the influence of hypervolemic hemodilution (Infusion of 500 cc hydroxyethyl starch 200,000/0.5 6% within 1 h) on macro- and microcirculation, fluidity of blood and conjunctival oxygen tension was investigated. Blood pressure and heart rate remained unchanged during and after the infusion. One hour after the infusion there was a tendency towards an increase in blood flow in the common carotid artery which then returned to normal again. The capillary circulation as well as the conjunctival oxygen partial pressure were significantly increased after 3 h. This correlated well with the decrease in plasma viscosity and erythrocyte aggregation. The effect of hemodilution using 6% middle molecular weight hydroxyethyl starch with a substitution degree of 50% on microcirculation was probably due to the rheological and not to the hemodynamic effect.
During a single blind study the influence of hypervolemic hemodilution (Infusion of 500 cc Elohäst 6%) on micro- and macrocirculation, transcutaneous pO2 and fluidity of blood of apparently healthy subjects was investigated. Blood pressure and heart rate remained unchanged during and after the infusion. One hour after the infusion there was a significant increase in the blood flow of the common carotid artery and the cutaneous circulation, and after 3 h a significant increase in conjunctival oxygen partial pressure was observed. The decrease in hematocrit was significant at all measuring points but most marked after 3 h (with 4.2 by volume). After 3 h and 6 h a significant increase in plasma viscosity and erythrocyte aggregation could be observed, whereas both parameters were unchanged during the early phase.
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During an open clinical trial the influence of hypervolemic hemodilution (Infusion of 500 cc Elohäst within 1 h) on macrocirculation, microcirculation and blood fluidity of healthy volunteers was investigated. Blood pressure and heart rate remained constant during the infusion period and later on. The decline in hematocrit after 6 h was four points, plasma viscosity and erythrocyte aggregation, however, increased significantly. Three hours after completion of the infusion a significantly elevated blood flow in the common carotid artery could be assessed with a return to approximately normal values after 6 h. The improvement of the microcirculatory flow took a longer period of time. After 6 h a significantly increased erythrocyte velocity in the nailfold capillaries along with a significant augmentation of transcutaneously measured partial oxygen pressure could be stated.
In an intraindividual comparison, the effects of a single dose of 600 mg naftidrofuryl on the fluidity of blood, the conjunctival and transcutaneous partial pressure of oxygen and blood flow through the micro- and macrocirculation were compared with placebo, given in random order to a group of 10 women, apparently healthy apart from showing hemorrheological abnormalities. There were significant increases in erythrocyte deformability, conjunctival partial pressure of oxygen, mean blood flow in the common carotid and femoral arteries. All increases were significant compared to both the initial values and the data in the placebo group. The maximal effect was observed after 1.5 h (capillary erythrocyte velocity, blood flow in the common carotid artery) or 3 h (conjunctival partial pressure of oxygen, blood flow in the femoral artery). After 4.5 h all effects had disappeared.
A new experimental method is described which permits estimation of flow ability of blood: measuring the yield shear stress with the erythrocyte-stasis-meter (ESM). This method is based on the phenomenon that pathological blood under low pressure behaves like a solid body. Knowing the pressure difference at the transition point from solid to fluid behavior and the geometry of the channel, the yield shear stress can be calculated.
An instrument was developed which can simultaneously determine the hematocrit and the total electrolyte concentration in blood and plasma respectively. It is possible to correct the hematocrit value for fluctuations of the total electrolyte concentration. Pilot studies of this device have been conducted on physiological and rigid erythrocyte suspensions and on plasma with various total electrolyte concentration. In the future, this device will be employed in analyzing blood and plasma of patients undergoing hemodialysis.
We have developed a device for the determination of the minimum shear force necessary to maintain complete disaggregation of erythrocytes and to simultaneously determine the hematocrit of blood samples (red cells in autologous plasma). A functional relationship between this shear force and the hematocrit was determined. The first derivative of the (measured) gamma Tmin as a function of the hematocrit was found to be identical (within limits) for all normal blood samples tested.
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The stent to be examined (Wiktor-Stent, Medtronic ESTC, Kerkrade, NL) was mounted into a closed-loop tubular-system and perfused with platelet-rich plasma (PRP). As controls the tubular-system without stent (as non-thrombogenic control) and secondly the tube filled with glassbeads (as thrombogenic control) were evaluated. A decrease in the number of singularly circulating thrombocytes correlated well with an increases in circulating platelet aggregates. The increasing activation of thrombocytes was demonstrated by immunolabelling of surface structures (CD 62) which become prominent on activation of thrombocytes. The increase in case of the non-thrombogenic controls is thought to be due to the action of the roller-pump. This increase was coincident with an increase in immunologically labelled GPIIb/IIIa receptors and well correlated with an increase in platelet activation as demonstrated by the elevated CD 62 label. In spite of the use of anticoagulation principles in the perfusion model, thrombin was generated (measured by the TAT-complex) in all three cases and the completed coagulation (measured by the occurrence of fibrin D-dimers) also happened. The amount of D-dimers was small, however, in the cases of non-thrombogenic controls and of tubes equipped with stents. Only after the contact of PRP with tubes filled with glass-beads a significant increase in D-dimers followed. In conclusion the implantation of a stent led to an activation, adherence and aggregation of thrombocytes to a somewhat greater extent as in the control-system. It has, however, a much less thrombogenic surface than glass-beads.
Congenital dysfibrinogenemia is based on different alterations in the structure of the fibrinogen molecule leading to a variety of disturbances in the clotting process. Clinical manifestations of the disorder are showing a wide range from asymptomatic states to mild bleeding diathesis as well as thrombotic complications. In this study two of the 14 patients with dysfibrinogenemia showed a history of mild bleeding while the others showed no clinical symptoms. As fibrinogen is also an important factor of the blood fluidity not only haemostatic but also rheological parameters were measured. Included in the study were 14 patients with ascertained dysfibrinogenemia in comparison to 11 non-affected relatives and a control group of 297 apparently healthy subjects. Plasma viscosity (p < 0.0001) and erythrocyte aggregation index (p < 0.00001) were significantly higher in the patients than in their healthy relatives and the control group. A pathologically increased erythrocyte aggregation was found in 10 of the 14 patients but only in 1 of the 10 relatives. The dysfunction of the fibrinogen molecule thus influences the aggregation process of the red blood cells to a greater extent than normal fibrinogen. Moreover, there seems to be a stronger influence of the dysfunctional fibrinogen molecule on the aggregation process than on plasma viscosity. To date the question if the enhanced erythrocyte aggregation in dysfibrinogenemic patients may be of any diagnostic interest and if there are significant differences between patients with bleeding diathesis and thrombophilia cannot be answered and remains to be cleared in further investigations.