Zbigniew Dabrowski

Bone healing after bone marrow stromal cell transplantation to the bone defect

In experimental studies on rabbits, osteogenic properties of stromal cells were confirmed after in vitro growth for 7 and 14 d. The cell suspension was percutaneously transplanted into a surgically produced bone defect in the rabbits radius. The bone scar produced was X-rayed, and histologically and mineralogically examined after 10, 20 and 40 d follow-ups. Differences in the bone defect healing process (the healing rate and the type of bone tissue produced) were shown between the experimental and the control foreleg. Within the experimental foreleg, healing was considerably accelerated with compact bone formation on a membranous matrix, whilst in the control foreleg, a coarse, fibrous woven bone on a cartilaginous matrix was dominant.

The activity of erythrocyte enzymes in rats subjected to running exercises

SummaryThe studies were carried out on male Wistar rats subjected to running within an electric rotating drum. The animals were divided into four experimental groups, differing one from another as to the duration of training. Each training session lasted 30 days. In the first group the daily run lasted 3 min, in the second group 5 min; in the third group, a 1 min run on the first day, and one min longer on each successive day; in the fourth group a 2 min run on the first day and for two min longer on each successive day.The determinations made prior to and after training included the peripheral blood erythrocyte (Er) and reticulocyte (Ret.) count, the hemoglobin concentration (Hb) and packed cell volume (PCV) and, determined by spectrophotometric methods, the activity of pyruvate kinase (PK), glucose-6-phosphate dehydrogenase (G6PD) and glutathione reductase (GR). Training induced an improvement of all enzymatic activities. The heavier the physical exertion, the more intensive was the enzymatic activity of red blood cells, due to the intensification of bone marrow erythropoetic activity under physical exertion and the appearance of young red cells in peripheral blood. All the experimental groups revealed a drop in erythrocyte count (Er), hemoglobin concentration (Hb), and hematocrit values (PCV), as well as an increase in the reticulocytes count (Ret) and in the activity of all the enzymes investigated. In the fourth group anemia was detected: prolonged endurance training decreased the RBC by 24.2%, Hb by 31.1%, PCV by 26.2% and increased the reticulocyte count by 881.6%. Pronounced loading with physical effort leads to shifts in the glucose utilization ratio along particular erythrocyte metabolic pathways. This change in enzymatic activities may prove to be one of the causes of faster elimination of old RBCs.

Red blood cell rheology in patients with chronic venous disease (CVD)

Rheological studies concerning aggregation and elongation of erythrocytes were carried out in 21 patients (mean age 56 years) with chronic venous disease (CVD) and 10 (mean age 45 years) healthy control subjects, with the use of a LORCA device. Higher values of parameters characterizing both erythrocyte elongation (EI) and aggregation (gammathr) in non-control patients than in the control group were found. These values differed significantly ranging from 1.13 to 8.23 Pa for the shear stress and gammathr in patients--432.14, in relation to the control group--166.5. It was proposed, that the increase in deformability may constitute a compensatory mechanism in subjects with chronic venous disease, due to increased resistance in their microcirculation.

Bone marrow cyclic nucleotides (cAMP, cGMP) in phenylhydrazine-induced anemia.

The studies were carried out on male Wistar rats. The animals were divided into two groups: control and experimental. The hematocrit value and reticulocyte count were determined in blood samples collected from control and experimental rats. The experimental rats received subcutaneous injections of phenylhydrazine manufactured by Sigma for the duration of 3 days. On the 5th day blood samples were collected from all the control and experimental animals and determinations of hematocrit and reticulocyte count were repeated. cAMP levels were determined in bone marrow extracts by means of a radiocompetitive method. The cGMP level was determined by a radioimmunological assay. A significant elevation of cAMP level was detected in experimental rats, whereas the cGMP level changed only slightly.

Reticulocytosis and Bone Marrow cAMP Level in Rats Following Physical Exercises

In the course of intensive physical exercises the blood serum erythropoietin level becomes elevated 16,21. Erythropoietin, being a protein hormone of a big molecular weight, does not penetrate the target cell, but is bound by a surface receptor 15 and affects the processes occurring within the erythropoietin-sensitive cell according to the generally accepted theory of the “second messenger”. As it has been demonstrated2,5,7 erythropoietin triggers an increase of cAMP in the bone marrow cells. On the other hand, an elevation in the intracellular cAMP concentration has been shown to stimulate erythropoiesis in vitro.

Post-Exercise Anemia during Examination in Rats

Numerous communications on the changes in the erythrocyte system as induced by physical exercises seem to be contradictory. Some authors point to an increase in hemoglobin concentration as well as erythrocyte and hematocrit count following single intensive physical exercises3,4,5,10,18,24 and prolonged physical training periods19,20. Others report a drop below initial values in the above mentioned hematological indices after single intensive physical efforts1,6,9,13,17 and also following training periods of various duration and intensity5,7,12,15,22. Moreover, cases of anemia have been described in athletes, and even in male and female members of the Olympic teams21,23. To stress the character of such anemia it has been called sports, athletes’, or post-exercise anemia11,12,16,22,25.

Effect of haemodialysate and its peptide fractions on lactate dehydrogenase activity in erythrocytes from healthy subjects and patients with end-stage renal disease

The effect of haemodialysate and its 3 peptide fractions on lactate dehydrogenase activity in erythrocytes was studied in patients treated by repeated haemodialysis for end-stage renal disease and in healthy subjects. Erythrocytes from dialyzed patients showed significantly lower LDH activity than those from healthy subjects. After a 3-h incubation with haemodialysate (675 and 450 μg protein/ml) or its peptide fraction III (270 and 190 μg protein/ml), a significant inhibition of LDH activity was observed. On the other hand, neither haemodialysate nor its peptide fractions inhibited LDH activity in red blood cells from patients with end-stage renal disease treated by repeated haemodialysis.