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Biomedical subjects

A I Kuznetsov

Publications and source records attributed to A I Kuznetsov.

At least 19 recordsLinked to original sources
PubMed2006

Chemical activity of photoinduced Ti3+ centers in titanium oxide gels.

We report on the chemical activity of trapped electrons in wet titanium oxide gels. These electrons are generated under the band gap irradiation of gels in the spectral range between 3.25 and 4.4 eV and stored as Ti3+ centers that absorb in the visible. Chemical processes in photoirradiated gels are generally similar to those earlier reported in TiO2 colloids; however, peculiarities exist. In particular, a high internal surface of gels strongly enhances interface reactions. Measurements of UV-visible absorption kinetics allow conclusions to be made about extremely high available traps concentration and the activity of all trapped electrons toward nitrate and nitrite anion reduction according to a heterogeneous photocatalytic mechanism.

Journal Article↗
PubMed2005

Light-induced charge separation and storage in titanium oxide gels.

We report on the interaction of light with a particular class of media--wet gels, which in contrast to sols of nanoparticles possess a macroscopic bulk structure, and which differ from conventional solids by the existence of the internal liquid-solid interface. We show, taking an absorption cross section of trapped electrons from Safrany, Gao, and Rabani [J. Phys. Chem. B 104, 5848 (2000)], that a separation of charges with quantum efficiency as high as 46% appears under the band-gap irradiation of titanium oxide gels: electrons are stored in the gel network as Ti3+ centers, whereas holes are stored in the liquid phase. Under a prolonged UV-laser irradiation, more than 14% of Ti4+ centers can be converted into Ti3+ . Their lifetime can be extremely long and exceeds months at room temperature. The trapped electrons are responsible for a "dark" absorption continuum covering the spectral range from 350 nm to 2.5 mum .

Journal Article↗
PubMed1993

[The assessment of a state of tension in a pilot by bloodless biochemical and immunological study methods].

Immunological and biochemical study of salivary liquid was carried out in order to estimate the tensity state of a pilot in operating conditions. These studies were conducted in the period of flight-development tests during man-compartible estimation of the cockpit of a light aircraft. The existence of natrium and secretory "A"-immunoglobulin in saliva in combination with psychophysiological parameters of tensity made it possible to reveal different levels of tensity proliferation (slight, moderate, strong and very strong). In the process of flight tests a correlative dependency was found between biochemical/immunological indices of salivary liquid, results of psychological testing, and informational/navigative loads of a pilot. This dependency was used during laboratory testings which were included in the complex of researches on man-compartible characteristics in the system "pilot-cockpit-aircraft".

Adult↗
PubMed1992

Mechanisms of thrombocytopenia in patients with lymphoproliferative diseases.

Different factors are involved in the development of thrombocytopenia in patients with lymphoproliferative disorders. Significant correlation was detected between the number of megakaryocytes in bone marrow and platelet count (r = 0.485, p = 0.002, n = 37) and significant difference between the number of megakaryocyte in patients with normal platelet count (> 200,000/microliters) and patients with marked thrombocytopenia (platelet count < 100,000/microliters). All patients in the latter group (n = 15) had a relatively low number of megakaryocytes. Low but significant reverse correlation was found between the level of platelet-associated IgG (PA-IgG) and platelet count (r = -0.249, p = 0.024, n = 82) and significant difference between the mean levels of PA-IgG in the groups of patients with platelet count > 200,000/microliters and < 100,000/microliters. PA-IgG were increased in 46% of patients in the total group and in 65% of patients with platelet count < 100,000/microliters. The correlation between platelet count and PA-IgG was about 2 times higher in splenectomized (r = -0.549, p = 0.005, n = 24) than nonsplenectomized patients. All splenectomized patients with platelet count < 100,000/microliters (n = 8) had a significant increase in PA-IgG. Serum antibodies were detected in only 7% of tested patients. This group was characterized by severe thrombocytopenia (in 6 of 10 patients--platelet count < 50,000/microliters) and a high incidence of haemorrhages (in 5 of 10 patients). Thus the depression of platelet production was suggested to be the basic cause of thrombocytopenia in lymphoproliferative disorders. Involvement of immune mechanisms was revealed in a large number of patients and correlated with a deeper and more complicated thrombocytopenia.

Antibodies↗
PubMed1992

[The use of hemoperfusion through a suspension of cryopreserved hepatocytes in acute liver failure].

The present work deals with results of intensive therapy and temporary organ substitution by using hemoperfusion through a suspension of living donor hepatocytes in 71 patients with acute hepatic insufficiency. Hemoperfusion was performed through a suspension of fresh living hepatocytes or through a suspension of cryo-conserved (during 60 days) living hepatocytes. Lethality was 37-42%.

Animals↗
PubMed1991

[Antithrombocyte antibodies in the serum and on the surface of the thrombocytes in patients with chronic lymphoproliferative diseases].

Antiplatelet antibodies were studied in patients with chronic lymphatic leukemia (CLL) using ELISA for detection of serum antibodies and RIA for determination of antibodies associated with platelet surface. Serum antibodies were identified in 1 out of 6 CLL patients with the platelet count 100,000-200,000 per microliter and in 7 out of 54 CLL patients with the platelet count lower than 100,000. Platelet-associated antibodies were not detected in patients with the normal platelet count, but were revealed in 14 out of 25 patients with the platelet count 100,000-200,000 per microliter and in 21 of 27 patients with the platelet count lower than 100,000 per microliter. The presence of a group of thrombocytopenic patients lacking serum or platelet-associated antibodies suggested that the development of thrombocytopenia in CLL could be mediated not only by antibodies but also by other pathogenic mechanisms, i.e. by the depression of megakaryocytes in bone marrow. Increase of the platelet count after steroid and cytostatic treatment in CLL patients correlated with decrease of antiplatelet antibodies. In splenectomized CLL patients, the increase of the platelet count and disappearance of hemorrhage occurred in patients with the low level as well as with the high level of antibodies after the operation.

Adrenal Cortex Hormones↗
PubMed1991

[Determination of antiplatelet antibodies on the surface of platelets by direct radioimmune method in patients with different types of immune thrombocytopenia].

Direct radioimmune assay (RIA) have been developed for detection of antibodies associated wild platelet membrane. Platelets from 12 patients with idiopathic thrombocytopenic purpura (ITP) and 27 patients with chronic lymphocytic leukemia (CLL) (platelet count (100,000 in 1 microliters) have been tested. Antibodies on platelets surface have been detected in all 12 patients with ITP and in 21 patients with CLL. In 6 CLL patients the number of immunoglobulins associated with platelets surface does not increase control level. It is possible, that in some CLL patients development of thrombocytopenia is mediated not only by platelet associated antibodies but by other mechanisms, one of which can be linked with the depression of megakaryocytes growth in bone marrow. Direct RIA for measurement of antibodies on platelet surface detect antiplatelet antibodies with higher frequency than indirect enzyme-linked-immunosorbent-assay (ELISA), developed earlier for assessment of antiplatelet antibodies in serum. Increase of platelet count in CLL patients after steroid and cytostatic treatment correlated with the decrease of platelet surface associated antibodies.

Autoantibodies↗
PubMed1990

[The effect of the spontaneous level of the chromosome aberration rate on its alterations after a single local irradiation].

With X-ray examinations of the stomach and duodenum, changes in chromosomal aberration frequencies in peripheral blood lymphocytes were shown to depend on the spontaneous level of these aberrations in patients exposed to a single local irradiation by 25 R. The cytogenetic efficiency of radiation exposure was found to be local in patients with the lower frequency of spontaneous chromosomal aberrations. A genetic genesis of the revealed dependence is supposed. The effect of irradiation on the correlation between radiosensitivity and radioresistance of the cytogenetic process is regarded as a possible mechanism of the appearance of the observed dependence.

Adult↗
PubMed1987

[Apheresis of euglobulins, cryoglobulins and the von Willebrand factor in vasculitis].

A method of apheresis of plasma euglobulin fraction, cryoglobulins and Willebrand factor was developed. In one session of plasmapheresis 1500-1700 ml of patient's plasma were removed, fractionated and returned. The method was used in 2 patients with immune complex vasculitides. In one of them the disease developed against a background of chronic active hepatitis, in the other patient it manifested itself in cryoglobulin- and cryofibrinogenemia. Clinical improvement was noted in both cases: the absence of myalgia, arthralgia, hemorrhagic eruption, and ulcerative-necrotic skin changes. The normalization of increased ristomycin-cofactor activity of Willebrand factor and CIC levels was noted in one case. A decrease in the content of plasma cryoglobulins, cryofibrinogen, and urine protein concentration (from 1.5 up to 0.03%) was noted in the other case. A possibility of the use of the method in other pathological conditions (DIC-syndrome, unstable angina, atherosclerotic angiopathy) accompanied by endothelial damage, was discussed. Willebrand factor multimers form complexes with low density lipoproteins therefore the removal of these complexes may be useful in the treatment of hypercholesteremia and atherosclerosis.

Chemical Precipitation↗
PubMed1985

[Combined operations in stomach cancer].

Experience with 217 combined operations for gastric cancer have shown them to be expedient. Five-years survival after combined operations for locally spread gastric cancer was obtained in 26,4 +/- 4,2% of the discharged patients.

Follow-Up Studies↗
PubMed1980

[Relation of sex and age to frequency of spontaneous chromosome aberrations in human peripheral blood lymphocytes. I. Age dynamics of the frequency of spontaneous chromosome aberrations and aberrant cells in peripheral blood lymphocytes].

Spontaneous frequency of chromosome aberrations in 680 individuals of both sex (from newborns to centenariants) has been studied. The age dependence of the frequency of chromosome aberrations has been revealed. The distribution of individuals according to the frequency of their chromosome aberrations corresponds to the Poisson's law. The analysis of the age dynamics of the frequency of chromosome aberrations made it possible to define three age periods. The first period involves the newborns with a high level of chromosome aberrations; the second period--individuals at the age of 1 to 20 years with the lowest level of aberrations; and the third one--individuals over 30 years old with continuous increase in the spontaneous frequency of chromosome aberrations with the age.

Adolescent↗
PubMed1978

[Formation of an esophageal-intestinal anastomosis in stomach cancer].

It is suggested to contruct entero-entero, and entero-esophageal anastomoses by means of the SPTU-suturing apparatus with detachable heads through the lumen of the anastomosed jejunum. The technic in use prevents the development of reflux-esophagitis, thus greatly accelerating the accomplishment of the most painstaking stage of the operation--constructing of the anastomoses, and reduced the incidence of suture incompetency of entero-esophageal anastomosis.

Esophagus↗