Platelet-collagen interaction: inhibition by ristocetin and enhancement by von Willebrand factor-platelet binding

The contribution of von Willebrand factor (vWF)-platelet binding to platelet-collagen interaction was examined in vitro. The binding of vWF to platelets was mediated and regulated by ristocetin. Subthreshold concentrations of ristocetin (less than or equal to 1 mg/mL), insufficient to cause ristocetin-induced platelet aggregation (RIPA), were added to platelet-rich plasma (PRP) prior to the addition of collagen. The collagen-induced platelet aggregation (CIPA) was modified by ristocetin and the degree of alteration was dependent on the ristocetin concentration. Response as a function of ristocetin concentration was designated the Collagen-Platelet Aggregation Response (CoI-PAR). In normal PRP the CoI-PAR was a progressive inhibition followed by decreasing inhibition and then an enhanced response. The enhanced response occurred over a narrow range of ristocetin concentrations (0.8 to 1.0 mg/mL). In the absence of vWF (severe von Willebrand's disease, Type I, vWF less than 1%) the CoI-PAR was a progressive, eventually complete inhibition with no enhanced response (with ristocetin concentrations up to 3.0 mg/mL). With addition of vWF to this PRP an enhanced response was observed at a ristocetin concentration inversely proportional to the vWF level. PRP from a patient with severe Hemophilia A showed a response within the normal range. Subthreshold ristocetin did not cause plasma protein precipitation or platelet release of 3H-serotonin, nor induce micro platelet aggregate formation. Digestion of platelet membrane glycoproteins (GP(s] with chymotrypsin demonstrated that upon removal of GPI, RIPA was absent, CIPA retained and the CoI-PAR was progressive inhibition, with no enhancement. With removal of GPs I, II, and III, RIPA, CIPA, and the CoI-PAR were absent. A dose-response 125I-vWF- platelet binding occurred with increasing ristocetin concentrations which was unchanged by the addition of collagen. These results demonstrated that ristocetin-platelet association inhibited CIPA, and vWF-platelet binding enhanced platelet-collagen adhesion and platelet aggregation. The in vitro-enhanced CIPA represents a vWF-dependent aggregation of sufficient magnitude to overcome the inhibitory effect of ristocetin. These studies demonstrate an influential interaction of ristocetin, vWF, and collagen with the platelet membrane and imply an important hemostatic contribution of vWF-platelet binding in platelet- collagen interaction.     

Sensitive skin evaluation in the Japanese population

Sensitive skin syndrome was first described in 1977; however, no robust study has been carried out to evaluate its prevalence in Japan. A national representative sample of the Japanese population over the age of 18 years was taken. Individuals were questioned by telephone and selected according to the quota method. When asked “Do you have a sensitive skin?”, 52.84% of men and 55.98% of women answered “rather sensitive” or “very sensitive”. There was no significant difference (P = 0.22) between the two sexes. The non‐response rate among respondents was zero, suggesting that the term “sensitive skin” held a meaning for the majority of the population. Concerning questions about the onset of a rash, tingling or irritation in the presence of various factors, such as emotional issues, cold, heat, sun, dry air, air‐conditioning, water, air pollution and temperature variations, respondents with rather sensitive or very sensitive skin responded “yes” more often than others: approximately three‐times more often for water (18.97%/6.15%), air pollution (39.29%/12.45%) and warm climatic conditions (29.74%/9.8%). To our knowledge, this epidemiological study is the first to focus on sensitive skin among Japanese people of this century. It is of particular interest for two reasons: (i) it was conducted on a representative sample of the Japanese population; and (ii) the methodology used was identical to that used for sensitive skin assessment studies conducted in Europe and the USA, making it possible to draw certain comparisons.     

Clinical results of Perftoran application: present and future

Clinical experience of Perftoran (commercial drug of low concentrated perfluorocheminal emulsion) applications is presented in some statistical data and in brief analysis of clinical trials and following clinical studies described in the Russian scientific literature. Observed data allow us to suppose that Perftoran facilitates oxygen delivery together with remaining red blood cells at blood replacements and will have more wider area for application than just a blood substitute. Its infusion alleviates symptoms of ischemia at different types of occlusion vessels disease, improves grafting in plastic surgery, diminishes inflammation and prevents rejection of transplants, activates detoxication functions of liver, inhibits retro-virus infection development. Local PF applications is able to accelerate wounds and ulcers healing.     

Immunoblot for verifying the results of screening of antibodies to hepatitis C virus in blood donors

A conclusion is made, on the basis of independent research results and published data, on the need to verify, compulsorily, the screening finding of donor blood for hepatitis virus by immunoblot and, in extra complicated cases, by PCR.     

A device for balancing the cups in donor blood centrifugation

It is important to well balance the loads of the opposite cups with plastic blood containers in order to correctly separate the donor blood into its components through centrifugation. A new balancer for centrifugation cups (USC5-01, manufacturer--Biophysical Instruments Ltd., Moscow) was tested at the Blood Center of Russia's Health Ministry. The original weights of all cups placed on the device weight sensors differed in all cases by readings of the light-emitting diode scale, which necessitated an appropriate balancing. The weight differences varied from 4 to 20 g, i.e. from 1 to 5 green lamps). The testing of the device verified its simplicity, convenience, and a shorter time spent on each balancing procedure; the device response lag to balancing made only 2-3 sec. The minimal out-of-balance index did not exceed 4 g, which ensures the obtaining of components meeting the requirements applied to them.     

Improvement in the technology of washing erythrocyte-containing transfusion media

A new device for preparing washed red cell components was proposed by the Sintez Co., Kurgan. The disposable containers were evaluated at the Center of Blood and Tissues, Military Medical Academy. The new system was found to be more effective, time-saving, cost-effective and decreased the risk of infectious complications as compared to the traditional methods for washing red cell components. Thus, the new device can be recommended for wide use in transfusion medicine.