In vivo release and turnover of secreted platelet antiheparin proteins in rhesus monkey (Macaca mulatta)

Human and rhesus monkey platelets secrete at least two antiheparin proteins: platelet factor 4 (PF4) and low affinity platelet factor 4 (LA-PF4). Neither of these proteins showed species-related antigenic differences. As determined by radioimmunoassay, the levels of PF4 and LA-PF4 antigen per 10(9) monkey platelets amounted to 10.7 and 20.3 microgram, respectively. One milliliter of monkey plasma prepared from blood collected into an anticoagulant composed of EDTA, prostaglandin E1, and theophylline solution contained 22.4 ng LA-PF4 and 8.0 ng PF4. Concentrations of these two platelet-specific proteins in monkeys closely resembled levels found in human platelets and plasma. Infusion of prostacyclin (PGI2) (100 or 300 ng/kg/min) into monkeys for 15 min resulted in a significant decrease of plasma levels of LA-PF4 antigen and of PF4 by 40%--60% (p < 0.0001). This decrease was related to the inhibitory effect of PGI2 on the secretion of platelets stimulated by a catheter or by venipuncture. Longer infusion of PGI2 did not produce further significant change. The supernate obtained after aggregation of human platelets stimulated by thrombin was injected into monkeys receiving PGI2 infusion. The disappearance of LA-PF4 antigen in monkey plasma followed a biphasic exponential curve with half-lives for the fast and slow components of 8.4 and 63 min. PF4 disappeared faster but followed the same pattern (half-lives for the fast and slow component of 2.1 and 70 min). Analysis of the experimental data suggests that the low levels of secreted platelet proteins in monkey plasma are related to their minimal in vivo release and to their rapid clearance.     

Clinico-morphological comparison in children with infectious endocarditis

As many as 21 children suffering from infectious endocarditis (IE) were examined for the clinical and morphological picture of the disease. The patients' age ranged from 2 to 15 years. In 15 children, IE developed in association with different congenital diseases; in one patient, in the presence of rheumatic heart disease, and in 5 patients, in unaffected heart valves. The sectional material was examined in 19 cases whereas the operational material in 2 cases. Analysis of the data obtained has shown that early diagnosis of IE (primary and secondary) may not infrequently be fairly difficult, which is likely to result in the late administration of antibacterial therapy. In addition to the involvement of the valvular apparatus of the heart, the majority of the patients demonstrated the signs of focal myocarditis and postmyocarditic cardiosclerosis, which is one of the causes of the development of refractory heart insufficiency. IE children mostly die from heart insufficiency and thromboembolism.     

Evaluation of immunity in children from rural localities and the levels of trace elements in environmental objects

Immunity was evaluated in 890 schoolchildren living in rural localities of the Central and Western lands of the Orenburg Region. There was a correlation between the immunological parameters of the examinees and the levels of trace elements in environmental objects. The children's immunity showed unilateral changes in the studied parameters as compared with the regional standards. The closest correlation was found between the absolute count of T lymphocytes, stab neutrophils, the levels of IgA, IgM in children and the content of I, Sr, Mn, Cr in cereals and vegetables, as well as between the levels of IL-2 and alpha-TNF and the blood concentrations of Cu, Fe, Cr, Ni, Co in the examined children. The immunological changes may result from the imbalance of trace elements in the studied environmental objects and biological substrates.