Relations between number and volume of erythrocytes and leukocytes in the human blood

Total concentration of erythrocytes and leukocytes, a relative contents of neutrophils, lymphocytes, monocytes, average volume of these types of cells, were determined in humans. Changes in the cell indices seem to be correlated and sex-dependent. Thus, erythrocytes and leukocytes are correlated in their contents and volume characteristics. A control mechanism seems to exist in humans, involving microcirculation in capillaries.     

Differential effect of retinoic acid on ADP and collagen induced platelet aggregation

Retinoic acid (RA) was found to inhibit ADP induced but not collagen induced aggregation of human platelets and the differential action is related to intraplatelet Ca2+ reflux. RA was active at concentrations as low as 10(-7) M and required 20 min prior incubation with platelet suspension in order to inhibit aggregation by ADP. All the steps in ADP induced but not collagen induced platelet activation, viz. hydrolysis of phosphatidyl inositol, phosphorylation of 20, 47 and 250 kDa proteins as well as increased association of actin with Triton X-100 insoluble cytoskeletal matrix were inhibited by RA. RA when used as an agent for differentiation induction of cell progenitor is likely to affect the platelet aggregation and thereby the haemostatic process.     

Hydrodynamic interaction between erythrocytes and leukocytes affects rheology of blood in microvessels

Hydrodynamic interaction between erythrocytes (RBC) and leukocytes (WBC) in a microvessel of size 20-40 micron, typical of a postcapillary venule, is studied using a two-dimensional computational model. The model is based on immersed boundary method, and it takes into consideration the particulate nature of blood by explicitly modeling individual blood cell, and cell deformation. Due to their highly flexible nature, RBC drift away from the wall and toward the center of a vessel creating a cell-free layer. It is shown here that the lateral motion of RBC is strongly affected in presence of a WBC, and is dependent on whether the WBC is non-adherent or firmly adhered. When the WBC is non-adherent, some RBC, depending on their initial radial locations and vessel size, may be deflected closer toward the wall, resulting in a decrease in the cell-free layer. The apparent viscosity of the whole blood containing both RBC and WBC is computed, and shown to be much higher than that containing RBC only. The increased viscosity cannot be accounted for by the contribution due to WBC only. This observation is in agreement with a previous in vivo measurement. Here we show that the additional flow resistance is due to the decrease in the cell-free layer resulting from the WBC-RBC interaction. It can be accounted for by a two-layer model of blood when the reduced values of the cell-free layer thickness are used. When the WBC is firmly adhered, RBC easily move away from the wall, and the cell-free layer is not significantly changed. In such cases, the major contribution to whole blood viscosity comes from the WBC alone. The hydrodynamic interaction between WBC and RBC, though it exists, does not contribute significantly when WBC are adhered.     

Effect of potassium leakage on reversible aggregation of human erythrocytes

Changes in the aggregation of human erythrocytes caused by polydextrane were studied under conditions influencing the rate of potassium leakage from cells to medium. It was shown that aggregation decreases as the leakage of potassium ions increases and is completely abolished at leakage rates higher than 2.5-3.0 mmol/l of erythrocytes per hour. The involvement of nonequilibrial electrokinetic phenomena in the inhibition of erythrocyte aggregation by ionic fluxes across erythrocyte surface is discussed. It is proposed that potassium leakage affects the erythrocyte sedimentation rate in clinical investigations.     

Effect of nitrobenzoic acid on methemoglobin content in blood and activity of antioxidative enzymes in erythrocytes]

Intraperitoneal administration of meta-nitrobenzoic, 3,5-dinitrobenzoic, 2,4,6-trinitrobenzoic and 3,5-dinitro-4-methylbenzoic acids to the white mice in a dose equal to LD50 has induced an increase in the methaemoglobin content in their blood. Total activity of dehydrogenases of pentosephosphate pathway, content of 2,3-diphosphoglycerate increase in response to the intoxication evoked by the mentioned acids. The acute intoxication does not practically change the activity of the key enzymes of antioxidant protection: superoxide-dismutase, catalase and glutathione peroxidase.     

Calcium transport in chicken leukocytes and erythrocytes

1. In the present study, Ca2+ uptake and Ca2(+)-ATPase activity of two different chicken leukocyte populations and erythrocytes isolated from 1- to 6-week-old chickens were determined. 2. The Ca2(+)-ATPase activity of the two leukocyte populations significantly increased at 3 weeks of age. Erythrocyte Ca2(+)-ATPase activity significantly increased at 2 weeks of age. 3. Calcium transport activities into the two leukocyte populations did not differ significantly with age.     

5-nucleotidase activity in rat leukocytes, erythrocytes and blood serum during radiation sickness

A study of 5-nucleotidase activity in the formed elements and blood serum of rats 1, 3, 7, 15 and 30 days after X-irradiation has demonstrated that it was increased in leukocytes at early times and inhibited at later times of the development of radiation sickness. In erythrocytes, inhibition of 5-nucleotidase activity was most pronounced on the 3d day. In blood serum, the enzyme activity was virtually invariable. The addition of ATP to the incubation medium normalized 5-nucleotidase activity.     

Effect of retinoic acid on indices of humoral immunity

The influence of all-trans- and 13-cys-methylretinoate on antibacterial and antiviral immunity was studied in experiments on noninbred C57Bl/6 and (CBA X C57Bl/6) F1 mice. All-trans-methylretinoate was shown to stimulate the production of antibodies to E. coli antigens, with the effect being dose-dependent. At the same time both compounds inhibited the production of inhibitors, interferon and antibodies to influenza virus.     

Effect of retinoic acid on the acylation of phospholipids in granulocytes in vitro

The influence of retinoic acid on the incorporation of [1-14C]palmitic acid and [1-14C]arachidonic acid into phospholipids was examined in guinea pig peritoneal granulocytes. All-trans-retinoic acid inhibited the incorporation of both fatty acids into phosphatidic acid and phosphatidylinositol. However, it stimulated the incorporation of both fatty acids into phosphatidylcholine but not other phospholipids. All-trans-retinoic acid was more effective than 13-cis-retinoic acid. The influence of all-trans-retinoic acid on the acylation of phospholipids was concentration-dependent with significant effect occurring at 2.1 microM. The loss of labeled fatty acids from prelabeled phospholipids and the transport of labeled fatty acids into granulocytes were not responsive to the presence of retinoic acid in the incubation media. These results suggest that retinoic acid may affect the activities of acyltransferases involved in the synthesis of phosphatidic acid, phosphatidylinositol and phosphatidylcholine.     

Effect of retinoic acid on chondrocyte glycosaminoglycan biosynthesis.

The effect of retinoic acid on glycosaminoglycan biosynthesis was investigated in rat costal cartilage chondrocytes in vitro. At levels of 10^?9 to 10^?8m retinoic acid, ³⁵SO₄ uptake into glycosaminoglycans was reduced 50%. At these low levels of retinoic acid there was no evidence of lysosomal enzyme release. The results are explained best in terms of modification of glycosaminoglycan synthesis, rather than accelerated degradation. Retinoic acid selectively modified the incorporation of ³⁵SO₄ or [¹⁴C]glucosamine into individual glycosaminoglycans fractions under the conditions studied. The relative incorporation of radiolabeled precursor into heparan sulfate (and/or) heparin increased three- to fourfold. The relative incorporation of radiolabeled precursor remained constant for chondroitin 6-sulfate, whereas incorporation into chondroitin 4-sulfate and chondroitin (and/or) hyaluronic acid decreased. Under the conditions studied, retinoic acid did not appear to be cytotoxic and did exhibit selective control over glycosaminoglycan biosynthesis. It is suggested that the decreased incorporation of ³⁵SO₄ into glycosaminoglycans at hypervitaminosis A levels of retinol may be accounted for by the presence of low levels of retinoic acid, a naturally occurring metabolite.