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Biomedical subjects

V V Pavlov

Publications and source records attributed to V V Pavlov.

At least 19 recordsLinked to original sources
PubMed2006

Spin and orbital quantization of electronic states as origins of second harmonic generation in semiconductors.

Basically different mechanisms of optical second harmonic generation (SHG) in semiconductors, induced by an external magnetic field H, have been identified experimentally by studying the diluted magnetic semiconductor (Cd,Mn)Te. For paramagnetic (Cd,Mn)Te the SHG response is governed by spin quantization of electronic states, in contrast with diamagnetic CdTe with its dominating orbital quantization. The mechanisms can be identified by the distinct magnetic field dependence of the SHG intensity which scales with the spin splitting in the paramagnetic case as compared to the H2 dependence observed for the diamagnetic case.

Journal Article↗
PubMed2006

[Low-dose accelerated hyperfractionated radiotherapy for local control of chemoresistant Hodgkin's disease (a prospective randomized trial)].

The results are evaluated of the combined treatment of 154 patients with relapsed refractory Hodgkin's disease, which was conducted using standard dosage of conventional chemotherapy. Out of those, 117 with residual lesions were randomized to receive either focal radiotherapy (20-24 Gy) in accelerated hyperfractionation (1.3-1.5 Gy, twice a day, at 5-hr interval) or 38-40 Gy in standard fractionation. Local control persisted in 85-97% of irradiated sites (median follow-up of 24 months), irrespective of irradiation technique. TTD being lowered down to 20-24 Gy due to use of accelerated hyperfractionation, the frequency of late-onset radiation injuries of paramediastinal lung tissue was lower than in standard treatment, with a subsequently lower fraction of patients with stage II fibrosis.

Adult↗
PubMed2005

Magnetic-field-induced second-harmonic generation in semiconductor GaAs.

We show that application of a magnetic field induces optical second-harmonic generation (SHG) in GaAs. This phenomenon arises from field-induced symmetry breaking causing new optical nonlinearities. A series of narrow SHG lines is observed in the spectral range from 1.52 to 1.77 eV that we attribute to Landau-level quantization of the band energy spectrum. The rotational anisotropy of the SHG signal distinctly differs from that of the electric-dipole approximation. Model calculations reveal that nonlinear magneto-optical spatial dispersion that comes together with the electric-dipole term is the dominant mechanism for this nonlinearity.

Journal Article↗
PubMed2005

[Optimization of isolation of the concentrate of stem cells from the umbilical blood].

AIM: To study correlations between body mass and height of the newborn, Apgar scale estimates, gestation time, volume of the obtained umbilical blood (UB), number of nucleated cells (NC); to compare manual and automatic modes of UB processing. MATERIAL AND METHODS: 330 procurements of UB were made, 230 (69.7%) samples were frozen. Comparison of 2 techniques of UB processing was made in 73 cases of double centrifugation with hydroxyethylstarch (HES) and 47 cases of using separator Sepax (Biosafe, Switzerland). Blood cell count before and after UB processing and number of CD34+ cells were estimated. RESULTS: A correlation analysis was made of dependence of the volume of 102 samples of UB on the weight (r = 0.268, p < 0.01) and height of the fetus (r = 0.203, p < 0.05), estimation by Apgar scale (r = -0.092, p < 0.1) and gestation term (r = -0.003, p > 0.1); analysis of the number of NC dependence on the volume of UB (r = 0.102 p < 0.1), mass (r = 0.073 p > 0.1) and fetus height (r = 0.121 p > 0.1), gestation time (r = 0.159 p > 0.1), Apgar scale assessment (r = -0.174 p > 0.1). In manual UB management NC yield made up 71.9 +/- 6.7%, in automatic--81 +/- 8.0% (p < 0.05). Percent of erythrocytes removal was 73 +/- 5.7% and 80.5 +/- 6.1% (p < 0.05), respectively. CONCLUSION: A weak correlation was found between UB volume, mass and height of the fetus. The number of NC in UB depends on none of the parameters. Automatic processing of UB provides a greater release of NC and better elimination of erythrocytes in minimal risk of contamination.

Antigens, CD34↗
PubMed2002

Agar cultures of human clonogenic hemopoietic precursor cells for early diagnosis of some myeloproliferative diseases.

Growth characteristics of human hemopoietic cells in erythremia and chronic myeloid leukemia were studied using agar cultures with and without hemopoietic growth factors. Agar cultures, similarly to cultures on other semisolid media (plasma clot, methylcellulose) can be used for early differential diagnosis of polycythemia vera (erythremia) and secondary erythrocytosis: erythremia, but not erythrocytosis, is characterized by spontaneous (erythropoietin-independent) formation of colonies from erythrocyte precursor cells. Spontaneous colony formation from granulocyte-macrophage precursor cells can serve as an important test for early diagnosis of chronic myeloid leukemia. The study of colony formation from granulocyte-macrophage precursors and of the capacity of bone marrow cells to form colonies from hemopoietic stromal precursor cells revealed new characteristics of the studied myeloproliferative diseases. Presumably, spontaneous colony formation from erythrocytic and myeloid precursors should be regarded as a sign of tumor transformation of the studied hemopoietic cells.

Agar↗
PubMed2002

[Use of thymodepressin for treating autoimmune cytopenia].

AIM: To study influence of thymodepressin on the course of autoimmune cytopenia. MATERIAL AND METHODS: Thymodepressin is a new synthetic hemoregulatory dipeptide (gamma-D-Glu-D-Trp). It was used for the treatment of 22 patients with autoimmune cytopenia. RESULTS: Hemoglobin levels were elevated in autoimmune hemolytic anemia and platelet levels were high in idiopathic thrombocytopenic purpura. A thymodepressin course resulted in a fall of total lymphocyte count and activated CD3+CD69+ lymphocytes. CONCLUSION: The above results, safety, absence of toxicity and allergenicity, parenteral and intranasal useability open perspectives for further studies of therapeutic action of thymodepressin as an immunodepressant in autoimmune processes.

Adult↗
PubMed2001

Second harmonic generation in the centrosymmetric antiferromagnet NiO.

In spite of the fact that inversion is a symmetry operation of both the crystalline and the magnetic lattice of NiO, second harmonic generation (SHG) has been observed below the Néel temperature. A spectroscopic study shows that the signal is due to combined magnetic-dipole and electric-dipole transitions between the (3d)(8) levels of the Ni(2+) ion in the crystal field. The SHG is resonant in both the incoming and the outgoing light waves and thus greatly enhanced. A quadratic coupling of the nonlinear polarization to the order parameter was found. This allows the investigation of individual domains.

Journal Article↗
PubMed1999

[Complications of sorption-application therapy of purulent wounds].

A retrospective analysis of 187 case records was made for elucidation of the frequency of development of complications in sorption-applicational treatment of festering wounds. It was revealed that late after strewing sterile sorbent into the wound in 6.4% of patients the development of fistulas and going out of preparation granules though fistula occurred. It is concluded, that sorbent's granules incapsulate together with living microorganisms adsorbed on their surface. For prevention of this complication the corbent is recommended to be introduced into the wound in small porous containers, which provide quick replacement of the preparation during wound dressing and its complete elimination in the end of healing.

Adult↗
PubMed1999

[Method of medicamentous saturation of lymphatic system].

Data of experimental study in 18 mongrel dogs followed by clinical trial in 96 patients are represented, which concerns a method of indirect medicamentous saturation of lymphatic system, consisted in creation of medicamentous subcutaneous infiltration in the thighs followed by pneumocompression. Gentamycin contents in blood lymphatics and organs of experimental animals was studied in various periods of time. The obtained data have determined identity of the effect with the method of introduction of the antibiotics together with the media, which possess hyaluronidaze-like action, and followed by 2 hours duration phlebohypertension (by V.M.Buyanov, 1991). It promotes reduction of time for the procedure more than 3 times and gives possibility to avoid introduction of additional preparations, which are unnecessary load to the procedure. Gentamycin contents in blood serum of patients in various time intervals are demonstrated.

Adult↗
PubMed1999

[Complications of indirect lymphotropic therapy in patients with suppurative wounds].

With the aim to reveal the frequency of complications in indirect lymphotropic therapy, retrospective analysis of 2136 case records of patients with festering wounds was carried out. In 1.59% of patients the following complications in the area of introduction of preparation were detected: protracted oedemas of hands and feet, severe painful syndrome, infiltration, necroses of soft tissues and the areas of atrophy and aseptic inflammation. Most commonly the complications arose in patients with peripheral circulation disturbances. The authors suggested this method of treatment to be contraindicated in peripheral blood flow disturbances and before its application the additional examination for revealing vascular disturbances is obligatory. In cases of painful syndrome, oedema, infiltration, hyperemia in the area of introduction of the drugs one day after the injection, indirect lymphotropic therapy should be discontinued.

Anti-Bacterial Agents↗
PubMed1999

[Emission tomography in the diagnosis of ischemic heart disease].

Myocardial perfusion scintigraphy was made at rest and during bicycle ergometer exercise to diagnose coronary heart disease (CHD), to define the site and extent of left ventricular aneurysms, and to determine the compensatory potentialities of coronary circulation, to evaluate the efficiency of drug therapy. This was performed on a two-detector emission tomograph by using 99mTc. The data obtained were processed by two protocols: 1) tomographic heart specimens and 2) large protruding eye. In patients with a questionable diagnosis, the method evidenced stenotic coronary arteries in 60% of cases and exclude coronary abnormality. In CHD patients, exercise testing could reveal the extent of resting perfusion defects and new defects, i.e. define the reserve potentialities of coronary circulation, which is of great prognostic value. The site and extent of lesions were specified in extensive myocardial cicatricial lesions and left ventricular aneurysms.

Adult↗
PubMed1997

[New developments in understanding the compensatory hematological reactions and their outcomes in local fractionated therapeutic gamma irradiation].

We have carried out a study of the bone marrow status in both irradiated and non-irradiated zones of 56 patients with stage I-II Hodgkin's disease in complete 9-12 (33 patients, group 1) and 18-23 (23 patients, group 2) year remission after therapeutic irradiation of the supradiaphragmatic lymphatic collectors at a dose of 40 Gy with irradiation of the spleen (33 patients) or splenectomy (23 patients). The total count of myelokaryocytes, myelogram, a relative and absolute content of lymphoid cells, immature granulocytes and elements of erythroid series were calculated in the aspirates from the exposed to radiotherapy sternum and non-irradiated upper portion of the ileum. The number of granulocyte-macrophage (CFU-GM) and stromal (CFU-F) precursor cells were defined using in vitro culture technique. There was a complete annihilation of the bone marrow in the irradiated zones, when the dose exceeded 35 Gy in 3-4 weeks. The concentration of myelokaryocytes, immature granulocytes, erythronormoblasts, CFU-GM, CFU-F in non-exposed bone marrow were significantly lower in all patients of group 2 than in normal subjects and in group 1 patients. Absolute lymphoid count in patients with 18-23 year remission was found to be normal but was considerably reduced in comparison to patients of group 1. These changes may be the result of the previous hyperactivity of the non-irradiated bone marrow which could be a cause of stem cell compartment depletion. The differential calculation of compact and diffuse subpopulations of CFU-F revealed a significant reduction of compact colony-forming CFU-F in both irradiated and unexposed bone marrow. Almost all the stromal precursor cells from irradiated zone formed diffuse colonies in cultures. These results confirm experimental data concerning greater radiosensitivity and proliferative potential of CFU-F, forming compact colonies versus diffuse colony-forming CFU-F. Aplasia of the irradiated bone marrow and hypoplasia of the non-irradiated bone marrow 18-23 years after radiotherapy completion coexisted with normal circulating CFU-GM and granulocyte blood count suggesting a compensatory mechanism involving a mitotic amplification between the progenitor cell and the final differentiated cell.

Adult↗