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Biomedical subjects

B Szabó

Publications and source records attributed to B Szabó.

At least 19 recordsLinked to original sources
PubMed1992

Prevalence and specificity of lymphocytotoxic antibodies in different stages of HIV infection.

Sera obtained from 27 HIV-infected persons were investigated for complement-dependent humoral cytotoxicity. Uninfected as well as HTLV-IIIB-infected H9 cells were used as cellular targets either before or after stimulation by phytohemagglutinin (PHA) or concanavalin A (Con-A). The degree of cytotoxicity was determined by 51Cr-release assay. Two different antibodies could be found in sera of HIV-infected persons, one being directed against HIV-induced cell surface component(s) and the other reacting with structure(s) present on activated T4 cells. Asymptomatic HIV-carries were found to have antibodies exerting complement-dependent cytotoxicity to HIV-infected T4 cells. These antibodies were reactive mainly after stimulation of HIV-infected target cells by Con-A. Sera of ARC and AIDS patients contained autoantibodies reactive with PHA-stimulated or HIV-infected T4 lymphocytes. These data suggest that HIV-specific antibodies represent an anti-viral immune defense, while autoantibodies may be important in destruction of the immune system in AIDS.

AIDS-Related Complex↗
PubMed1991

Neutralizing and complement-dependent enhancing antibodies in different stages of HIV infection.

Reclustering and indirect immunofluorescence assays on MT-4 cells [carrying both CD4 and complement receptor type 2 (CR2)] were used to measure neutralizing and enhancing antibodies in sera obtained from HIV-1-infected individuals. Heat-inactivated sera were tested before and after mixing 1:1 with fresh seronegative human serum. Using heated samples, neutralizing antibodies were found in 20 out of 20 and 11 out of 19 serum samples of asymptomatic and symptomatic [AIDS, AIDS-related complex (ARC)] HIV-seropositive patients, respectively. In complement-restored samples, neutralizing activity was found in eight sera of asymptomatic patients and in none of the sera of AIDS and ARC patients; enhancing activity could be detected in four and 12 sera, respectively. A significant positive correlation was observed between the titres of neutralizing antibodies measured in the complement-restored samples and the absolute number of CD4+ lymphocytes. These findings indicate that the appearance of complement-dependent enhancing antibodies coincident with the loss of neutralizing antibodies may indicate a poor prognosis in HIV infection.

AIDS-Related Complex↗
PubMed1991

Evaluation of the effectivity of Nitromint spray in comparison with sublingual tablet in emergency and ambulance practice.

The effect of Nitromint sublingual tablet and Nitromint aerosol (EGIS) has been studied in ambulance practice. Both drug forms relieved or controlled the complaints and symptoms, and proved to be effective in a great number of cases. Due to it's easier storage and easier applicability the aerosol is more advantageous than the sublingual tablet. Occasionally the simultaneous use of the two products is also beneficial. Supposedly the indication field of nitroglycerin will be extended in the near future and Nitromint preparations will be used in oxyology also for controlling other clinical conditions in which smooth muscle spasm has a major role.

Administration, Sublingual↗
PubMed1990

Detection of HIV in the peripheral mononuclear cells of asymptomatic haemophiliacs in Hungary.

The presence of virus in peripheral blood mononuclear cells of asymptomatic antibody positive haemophiliacs was detected by assaying for reverse transcriptase and confirmed by electron microscopy and immunofluorescence. HIV has been detected in 5 out of 7 individuals. In order to investigate strain variation, supernatant fluids of cultures were added to H9 and MT-4 cells. Virus was recovered in MT-4 cells in 3 cases, whereas the H9 cells only supported the replication of 2 strains. Viruses isolated from asymptomatic haemophiliacs have a narrower range of infectivity than HTLV-IIIB.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Neutralizing antibodies and serum interferon levels in the different stages of HIV infection.

The sera of patients infected with HIV were investigated for neutralizing antibodies (NA) and interferons. All samples from asymptomatic HIV carriers contained NA in high titres. In the sera of patients with AIDS related complex and AIDS the antibodies were found rarely and in lower titres. An early peak of acid-labile interferon (IFN)-alpha was observed in asymptomatic HIV-infected persons, and a late peak was found in AIDS patients. The data suggest that HIV NA may have beneficial effect in the asymptomatic phase. The presence of acid-labile IFN-alpha may indicate stimulation of IFN system by HIV-infected cells.

AIDS-Related Complex↗
PubMed1989

Complement-dependent cytotoxicity of antibodies reactive with HIV-induced cell surface antigens in HIV-carrying haemophiliacs.

Sera obtained from HIV-infected as well as uninfected haemophiliacs and from healthy subjects were investigated for the presence of lymphocytotoxic antibodies. Using the 51Cr-release test, HIV-infected haemophiliacs were found to produce serum antibodies exerting complement-dependent cytotoxic effect on HIV-infected T4 cells. The antibodies were reactive mainly when HIV-infected target cells were stimulated with concanavalin-A. Results of complement-dependent antibody cytotoxicity and indirect membrane immunofluorescence tests suggest that envelope antigen(s) of HIV may be the target(s) for cytotoxic antibodies.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Retrovirus-neutralizing antibodies in AML and AMMoL patients: stage-specific distribution.

Plasma samples of patients with AML or AMMoL were tested for antibodies reacting with gp70 antigens of BaEV and GaLV as well as for antibodies neutralizing BaEV or GaLV. Both frequency and titer values of antibodies were higher in remission than in blastosis. Neutralizing activity could be detected only in those plasma samples which contained antibodies to the appropriate gp70 antigen. The data suggest the presence of retroviruses in humans as antigenic stimuli for the immune system in AML and AMMoL.

Antibodies, Viral↗
PubMed1988

Interferon production in myelo- and lymphoproliferative diseases. I. Spontaneous interferon production in acute and chronic leukaemias.

Blood plasma interferon (IFN) of patients with acute myeloid (AML) and chronic granulocytic (CGL) and with acute and chronic lymphoid leukaemia (ALL and CLL) was measured by bioassay and characterized by neutralization with anti-human-IFN-alpha treatment. Elevated IFN-alpha level (60-125 IU/ml) was found in the quiescent phase of CGL as compared to the control samples (15 +/- 10 IU/ml). No significant differences could be found between plasma IFN of patients suffering from the blastic crisis of CGL and control persons. Analogous results were obtained in experiments with plasmas of AML patients, regardless the stage of the disease. Elevated IFN-alpha production (60-100 IU/ml) was found in patients being in the remission phase of T-cell ALL but only in one case in the progressive phase of the disease. No significant elevation of plasma IFN level was demonstrated in patients with O-cell ALL and B-cell CLL, as compared to the control samples.

Blast Crisis↗
PubMed1988

Cytotoxic activity of lymphocyte subpopulations against autologous tumour cells in patients with myeloid leukaemias and preleukaemic disorders.

Autologous lymphocyte populations from different phases of chronic granulocytic leukaemia (CGL), acute myeloid leukaemia (AML) and preleukaemic disorders were compared for cytotoxic activity. 51Cr-release tests showed that T lymphocytes from the quiescent phase of CGL and from the remission phase of AML exerted cytotoxic activity against autologous tumour cells. Such activity was also found in patients with potentially preleukaemic haematological disorders characterized by cytopenia, but not in polycythaemia vera patients. In the majority of cases cytotoxic activity of T lymphocytes could be blocked by native gp70 antigens of gibbon ape leukaemia virus (GaLV) and baboon endogenous virus (BaEV). Blocking effect of carbohydrate-free gp70 as well as p15(E) antigens could be observed less frequently. The role of cell-mediated immune response to oncovirus antigens in the course of myeloproliferative diseases is discussed.

Blast Crisis↗
PubMed1987

gamma-Aminobutyric acid stimulates pituitary growth hormone secretion in the neonatal rat. A superfusion study.

The putative inhibitory neurotransmitter gamma-aminobutyric acid (GABA) elicited a dose-dependent increase in GH secretion from the pituitary of newborn rats. GH secretion increased within 3 min after GABA administration with a peak response at 5-6 min. The lowest effective dose of the GABA agonist muscimol was about 10 times smaller than that of GABA. The GABA effect was antagonized by picrotoxin and bicuculline, suggesting that GABA acts at GABA-A type receptors. The pituitary responsiveness to GABA gradually decreased during the second and third postnatal weeks. If the neonatal pituitaries were continuously exposed to GABA for 3 h GH secretion rapidly increased to a maximum within the first 10 min and then gradually decreased to a less elevated level by 1 h and remained at this level for the next 2 h. After 3 h of GABA exposure muscimol had no effect on GH secretion but human pancreatic GH-releasing factor stimulated it, indicating receptor desensitization during prolonged GABA administration. The significance of GABAergic regulation of GH secretion in the neonate is emphasized by the finding that simultaneous administration of picrotoxin diminished the GH releasing activity of the hypothalamic extract of 2-day-old rats by more than 60%. These results indicate that in the postnatal period the regulation of GH secretion differs from that of the adult animal and GABA might play an important role in the maintenance of the high GH secretion during the first days of life.

Animals↗
PubMed1987

Studies on viral etiology of angioimmunoblastic lymphadenopathy.

Plasma samples of patients with angioimmunoblastic lymphadenopathy (AIBL) were tested for anti-HTLV antibodies and for interferon content. Out of 12 patients 4 had antibodies to HTL-III. Two of these plasma samples contained antibodies reacting with HTLV-I and HTLV-II, too. Activated interferon (IFN) system was found in patients with clinical remission of AIBL, as it was detected by IFN titration in their plasma samples. Data suggest the etiological role in AIBL of virus(es) related to the HTLV family.

Adult↗
PubMed1986

Cytotoxicity of lymphocytes and antibodies against autologous tumor cells in patients with myeloid leukaemias and preleukaemic disorders. III. Stage-dependence of oncovirus-specific immune response.

Lymphocyte and plasma samples from the quiescent and blastic phase of chronic granulocytic leukaemia (CGL) and from the blastosis and remission of acute myeloid leukaemia (AML), were compared for cytotoxic activity. Target cells were collected from the blastic phases of diseases. 51Cr-release tests showed that the lymphocytes and plasma samples from blastic crisis of CGL had no cytotoxic activity for autologous blast cells. In contrast, cryopreserved lymphocytes and plasmas from the quiescent phase of CGL proved to be cytotoxic for the autologous tumor cells, and their effect could be blocked by native gp70 antigens of gibbon ape leukaemia virus (GaLV) and baboon endogenous virus (BaEV). A blocking effect was less frequently exerted by carbohydrate-free gp70 and p15(E) antigens. A similar relationship was found between the blastosis and remission stage of AML, however, out of the antigens of BaEV only the native gp70 showed a marked blocking effect.

Antibodies, Neoplasm↗
PubMed1985

Reduced responsiveness of glomerulosa cells after prolonged stimulation with angiotensin II.

The purpose of this study was to examine whether sustained exposition to angiotensin modifies the responsiveness of adrenal glomerulosa cells when extra-adrenal factors are eliminated. Isolated rat glomerulosa cells were stimulated for 6 h in a superfusion system with angiotensin II or potassium. Their responsiveness to angiotensin II, potassium, and corticotropin (ACTH) was examined before and after the superfusion. Stimulation of the cells during the superfusion with angiotensin II or with potassium reduced their responsiveness to all three stimuli. The steroid synthesis inhibitor aminoglutethimide, applied during the superfusion, overcame the effect of potassium but failed to influence that of angiotensin. This suggests that the reduced responsiveness after stimulation with potassium is related to the increased steroid production whereas the action of angiotensin is independent of that. The results establish the existence of desensitization to angiotensin in the absence of modifying extra-adrenal factors.

Adrenal Glands↗
PubMed1985

Detection of main core proteins of simian C-type viruses and human retrovirus HTLV and antibodies to them in patients with lymphoid malignancies.

Peripheral leukocytes or lymph node cells and blood plasma samples from patients with lymphoid malignancies were investigated for immunological markers of BaEV, GaLV and HTLV. Antigens and antibodies were shown with radioimmunoassay. Antigen related to the p30 core protein of BaEV could be detected in each cell type of leukaemias and lymphomas. Antigen related to the GaLV p30 was found mainly in B- and O-cell forms, while that related to the p24 protein of HTLV could be detected only in two T-cell malignancies. Antibodies reactive with these antigens showed a similar distribution.

Animals↗
PubMed1979

The 24Na-transport increasing effect of veratrine in frog sartorius muscle influenced by the tonicity, composition and temperature of the external environment.

The influence of tonicity, ionic composition and temperature of the incubating medium on the increasing effect of veratrine on 24Na transport in the frog sartorius muscle has been studied. (1) The effect of veratrine applied during 24Na loading on the rate coefficient for sodium loss depended on the tonicity of the medium. The rate of loss of 24Na from muscles loaded in the presence of veratrine was not affected if the muscles had been equilibrated in hypertonic medium. However, when treating the muscles with veratrine in isotonic medium during 24Na loading, we obtained a twofold increase in the rate coefficient for sodium loss. (2) The effect of veratrine applied during the desaturation period on 24Na efflux was also found to depend on the tonicity of the medium. Veratrine applied during the desaturation period increased the 24Na efflux in muscles equilibrated in isotonic Ringer's solution. However, when the muscles were equilibrated in hypertonic medium, veratrine did not influence 24Na efflux, not even after the rate of 24Na loss had been decreased by ouabain. (3) Hypertonic medium inhibited the Li uptake-enhancing effect of veratrine, while in isotonic medium veratrine had a marked enhancing effect. (4) In hypertonic medium lithium inhibited the otherwise characteristic increasing effect of veratrine on 24 Na uptake. (5) The increase of intracellular sodium concentration as a result of incubation in cold, potassium-free Ringer's solution did not influence the 24Na exchange-increasing effect of veratrine in isotonic medium. (6) The increasing effects of 0.1 and 0.5 mM veratrine on 24Na influx had the same degree at room temperature. However, at 5 degrees C 0.5 mM veratrine increased 24Na influx to a greater extent than 0.1 mM. (7) On the basis of our earlier experiments it has been suggested that the site of action of the 24Na uptake-increasing effect of veratrine could be the neural structures in the muscle equilibrated in hypertonic media. The present experiments confirm this suggestion and at the same time demonstrate that there are substantial differences in the mechanism of the sodium transport of veratrine-treated neural and muscle membranes, which become more apparent in hypertonic medium.

Animals↗
PubMed1978

The effect of veratrine on 24Na uptake by frog sartorius muscle in hypertonic media.

The effect of veratrine on 24Na uptake by sartorius muscles incubated in hypertonic media has been studied. 1. 0.1 mM veratrine increases 24Na uptake in muscles incubated even in different hypertonic solutions (normal Ringer + 300 mM sucrose or glucose or 150 mM NaCl). 2. 0.05 mM curare inhibits the 24Na uptake increasing effect of veratrine in hypertonic solution 3. 0.1 mM ouabain, whether in isotonic or hypertonic solution, does not influence the resting 24Na uptake, and does not decrease the 24Na uptake increasing effect of veratrine in isotonic media; however, in hypertonic solution it inhibits the 24Na uptake increasing effect. 4, 5 X 10(-8) M tetrodotoxin blocks completely the 24Na uptake enhancing effect of veratrine both in isotonic and in hypertonic Ringer's solution. 5. It is suggested that the sites of action of the 24Na uptake increasing effect of veratrine are the neural structures in muscle, in hypertonic media.

Animals↗
PubMed1977

Association of precipitins and coeliac disease.

Four fractions, fraction A,B, C, and D, were isolated from the aqueous extract of wheat flour on a Sephadex G-75 column. It was found that the repeated gel-filtrated fraction A reacts as an antigen with the sera of coeliac patients. On the basis of its molecular weight and amino acid compositions, it is gliadin. Each of the 28 coeliac patients had heat-stable precipitating antibody and higher than normal IgE levels were found in the sera of only three individuals. Specific antigliadin IgE in low quantity was found in only one case. The sera reacting with antigens in high titres were absorbed by anti-IgG and anti-IgA whereupon the antibody level considerably decreased. The main circulating antibody of the patients was IgG.

Amino Acids↗