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Biomedical subjects

J Popov

Publications and source records attributed to J Popov.

11 recordsLinked to original sources
PubMed1992

Acute lymphoid changes and ongoing immune activation in SIV infection.

Two features of simian immunodeficiency virus (SIV) infection are emphasized: a transitory decrease in CD4 T cells in the first 2 weeks of infection followed by CD8 T-cell rise, and immune cell activation occurring by 4 weeks and persisting throughout the illness. The short-term changes included a fall in CD4 T cells by 2 weeks with partial recovery by 4 weeks and a CD8 rise that starts at 2 weeks. Subsequent characterization of CD4 T cells showed reduced expression of HLA-DR and CD25 (IL-2 receptor alpha chain) antigens later in SIV infection. Immune cell activation is evident in increased serum levels of neopterin and soluble CD8 antigen. Serum beta 2-microglobulin changes are less marked. Activation of CD8 T cells is reflected by increased percentages of cells expressing HLA-DR antigen. The B-cell numbers increased late in the course of SIV infection. Increased expression of the CD78 (Leu 21) activation phenotype was also seen in some monkeys. The immune activation changes (serum neopterin levels) induced by SIV infection in rhesus macaques appear to be associated with duration of illness, although the number of monkeys observed until death were too few for conclusive data. Thus, immune activation as well as T-cell deficiency may reflect significant immunopathogenic processes in SIV-induced disease.

Animals↗
PubMed1991

[The effect of 2 thrombocytopoietic-active polypeptides on thrombocytopenia in mice irradiated with ionizing radiation].

The assumption that thrombocytopoietin preparations prepared in our own laboratory can prevent the decrease of the number of thrombocytes in the peripheral blood of animals irradiated by a sublethal dose of gamma-ionizing rays was tested in an experiment on mice. Two preparations were tested: one, with an influence on stem cells, which directs them in the direction of megacariocyte differentiation (Smp), and the other one which is essential for the endomitosis and production of thrombocytes (Stp). The results undoubtedly indicated that a decrease in the number of thrombocytes occurred in the peripheral blood of animals following irradiation without the use of the preparations mentioned above, and was mostly emphasized after 9 days. The fact that was also demonstrated was that this decrease is significantly lesser if the animals are treated, after irradiation, with both preparations together or only with preparation Stp which has an influence on the directed thrombocytopoiesis cells, while the preparation Smp does not show such an effect. On the basis of these results a conclusion was made that thrombocytopenia of irradiated subjects sets on as a consequence of a temporary lack of one of the two poietins of thrombocytopoiesis, meaning Stp, which can be of importance in the treatment of the acute radiation syndrome in man.

Animals↗
PubMed1990

[Radioimmunologic determination of growth factors. II. Comparative development of methods for the determination of hematopoietic growth factors].

On the basis of our long-term experience, presented are the current clinically useful methods for determining erythropoietin, the granulocytopoiesis growth factor and thrombocytopoietin with the results in their use. Facts are shown, concerning the long-used method of determining erythropoietin through the use of the biological test on polycythemic mice. In our conditions, mice treated with physiological solution (negative controls) have a Fe-59 incorporation below 0.5% of the given dose, while 0.2 units of the international erythropoietin standard (positive control) increases that incorporation to 3.0%. Also presented, are results of determining erythropoietin by means of the newest immunometric method which has shown exceptional features: the whole procedure, including necessary rinsings, lasts about six hours, and it is possible, in the course of one work day, to all at once precisely determine the erythropoietin concentration in 80 samples of human serum. This fact, as well as the outstanding sensitivity of the method which is about 2 mJ/ml (that is 50 times the sensitivity of the biological test) has as a result, the wide introduction of erythropoietin determination in the clinical use of today and the definition of its clinical importance. The measurement range of the method is from 2-200 J/L which can be extended further by specimen dilution. It is especially important that duplicate measurements at one point of the curve almost coincide, which indicates great method precision. The lowest measured concentration in our series amounted to 0 J/L and the greatest to greater than 250 J/L. Elevated values were found in 17 of the 114 serums.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

[Cesarean section in elder primiparae].

The frequency and indications for cesarean section for elderly primiparae are presented and compared with those for primiparae aged no more than 29 years and primiparea aged 30 to 34 years. With a mean frequency 1.75% of elderly primiparae, the operation took place in 60% of the cases in the year 1984 and in creased up to 80.95% during 1987. The most frequent indications for cesarean section in this group were: infertility 42.86% preeclampsia 11.43% dynamic dystocia 8.57%. A scheme for management of elderly primiparea that was introduced in obstetrical practice in order to lower the percentage of abdominal delivery, is presented.

Adult↗
PubMedDate not supplied

Psoralen and coumarin photochemistry in HSA complexes and DMPC vesicles.

The photochemistry and photophysics of several psoralens and coumarins have been examined in human serum albumin (HSA) complexes and dimyristoylphosphatidylcholine (DMPC) vesicles. Fluorescence spectroscopy indicates that there are multiple binding sites with polarities that are intermediate between those of acetonitrile and water for the substrates complexed to HSA. In the case of the 6,7-dimethoxycoumarin-HSA complex, laser flash photolysis experiments provide evidence for the formation of radical cation in addition to triplet. Radical cations are not detected for other coumarin-HSA complexes, either due to a lower yield of formation or to rapid reaction of an initial radical cation with adjacent amino acids. Fluorescence spectra for coumarins indicate that they are primarily solubilized in the polar headgroup region in DMPC vesicles. Consistent with this, radical cations generated by photoionization are detected in transient experiments. For dimethoxycoumarins the radical cation is long-lived, indicating rapid exit from the vesicle and decay in the aqueous phase. However, 4,5',8-trimethylpsoralen and 7-ethoxy-4-hexadecylcoumarin radical cations are much shorter-lived, presumably due to rapid decay by electron recombination in the vesicle. The results for both HSA complexes and vesicles indicate that radical ions may play a role in psoralen and coumarin photochemistry in a cellular environment.

Binding Sites↗