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Biomedical subjects

K Nagy

Publications and source records attributed to K Nagy.

At least 145 records · Page 8Linked to original sources
PubMed1984

Low prevalence in the UK of HTLV-I and HTLV-II infection in subjects with AIDS, with extended lymphadenopathy, and at risk of AIDS.

Antibodies reacting selectively with human T-cell leukaemia virus type I (HTLV-I) were detected in approximately 5% patients with extended lymphadenopathy syndrome (ELAS) and in less than 1% of unselected homosexual patients and drug abusers. None of 22 patients with acquired immunodeficiency syndrome (AIDS) had HTLV-I antibodies and neither did 85 haemophiliacs and 940 blood donors. 3 out of 113 drug addicts had high titres of antibodies to human T-cell leukaemia virus type II (HTLV-II). A T-cell line was derived from 1 of the seropositive ELAS patients. This line was found to be infected with, and releasing, HTLV-I. Infection by HTLV-I and HTLV-II retroviruses thus occurs more frequently in ELAS patients and drug addicts than in the UK population as a whole, but the low prevalence of these infections in ELAS and AIDS patients indicates that these two strains of lymphotropic retroviruses have no aetiological role in ELAS and AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1984

Effect of soya consumption on hepatic monooxygenase enzyme system and some lipid parameters in rats.

Young male rats were fed with diets containing Hungarian soya products (extruded or granulated soya preparates) as the only source of protein for four weeks. The weight gain of the animals, the cholesterol and triglyceride content of liver and the activity of the hepatic monooxygenase system were studied. 20% soya protein in the diet (either from extruded or from granulated soya products) supplemented with sulphur containing amino acids met the protein requirement of the young growing rats. In a separate experiment the protein depletion-repletion method was used to investigate the effect of Purina 500 E soya protein isolate on the above mentioned parameters. The results indicate that diets containing 20% soya protein are satisfactory for the regeneration of the protein depleted animals.

Animals↗
PubMed1984

Effect of lipoproteins on aldosterone production by isolated glomerulosa cells.

We have studied the effects of human high density and low density lipoproteins on adrenocorticotropin (ACTH)-induced aldosterone production by isolated glomerulosa cells obtained from lipoprotein-deficient rats. ACTH increased basal aldosterone production, and the addition of either lipoprotein fraction further enhanced ACTH-induced aldosterone production. This increase could be shown at physiological lipoprotein-cholesterol concentrations. These data are compatible with a role of both high density and low density lipoproteins in supplying cholesterol to aldosterone-secreting glomerulosa cells.

Adrenal Glands↗
PubMed1984

Alterations in the molecular weight distribution of proteins in rat brain synaptosomes during aging and centrophenoxine treatment of old rats.

Properly prepared membrane proteins of brain synaptosomes of 2-, 12- and 24-month-old CFY female rats were filtrated on a Sepharose 2B gel. The molecular weight distribution showed an age-dependence: there was a clear shift toward the higher molecular weights in the adult and old rats. The observed alterations reflect an increased cross-linking of the proteins during aging due most probably to the OH free radical damage of the cell components. Centrophenoxine treatment for 2 months reversed this phenomenon in the old animals: the high molecular weight fractions decreased and the lower ones increased in the treated animals as compared to the old, untreated rats. The results support the membrane hypothesis of aging and contribute to a better understanding of the biological effects of centrophenoxine.

Aging↗
PubMed1984

Pseudotypes of human T-cell leukemia virus types 1 and 2: neutralization by patients' sera.

Pseudotypes of vesicular stomatitis virus (VSV) bearing envelope antigens of human T-cell leukemia virus (HTLV) types 1 and 2 were prepared by propagating VSV in cells lines productively infected with HTLV. Plaque assays of VSV (HTLV) pseudotypes were employed to determine the presence of (i) HTLV receptors on cells and (ii) neutralizing antibodies in the serum of patients with adult T-cell leukemia-lymphoma (ATLL). Cell surface receptors for HTLV-1 and HTLV-2 were found on nonlymphoid cells of human and mammalian origin. Neutralizing antibodies specific to VSV(HTLV-1) were found in sera of ATLL patients in titers varying from 1:50 to 1:30,000 and did not correlate closely with antibody titers for internal viral antigens. Sera from ATLL patients in the United Kingdom (Caribbean immigrants), United States, and Japan completely neutralized VSV (HTLV-1), indicating that the HTLV isolates from these distinct geographic regions represent a single envelope serotype. Neutralization of VSV (HTLV-1) was more specific and more sensitive than assays of syncytium inhibition. No cross-neutralization was observed between bovine leukosis virus and HTLV, and only limited cross-reaction was found for envelope antigens of HTLV-1 and HTLV-2. These studies show that VSV (HTLV) pseudotypes can be readily used to screen for neutralizing antibodies in patients' sera and to distinguish HTLV envelope serotypes.

Antigens, Viral↗
PubMed1983

Spin label studies on synaptosomal membranes of rat brain cortex during aging.

Membrane lipids of brain synaptosomes of 2, 12 and 24 months old rats were labeled by stearic acid spin probes with a doxyl group in the C-5 and C-16 position, respectively. We demonstrated that the hydrophobic region of synaptosomal membranes became more rigid during the life span studied, and the region located nearer the surface of membranes displays a significantly decreased fluidity only in the oldest group. Membrane proteins labeled with a nitroxide derivative of maleimide suggest that conformational changes take place during aging.

Aging↗
PubMed1983

Productive infection and cell-free transmission of human T-cell leukemia virus in a nonlymphoid cell line.

Human T-cell leukemia virus (HTLV), American PL isolate, was transmitted by cocultivation and by cell-free filtrates to a nonlymphoid human osteogenic sarcoma (HOS) cell line, designated HOS/PL, but not to nine other lines bearing receptors for HTLV. HOS and HOS/PL cells are not dependent on interleukin-2 and do not express interleukin-2 receptors that are recognized by anti-Tac monoclonal antibody. HTLV released by the Japanese MT2 cell line was also transmitted to HOS cells. The infected HOS cells release substantial titers of progeny HTLV which is antigenically indistinguishable from parental virus and is able to transform T cells.

Antigens, Surface↗
PubMed1983

Human T-cell leukemia virus type I: induction of syncytia and inhibition by patients' sera.

HTLV-producing T-cell lines induce cell fusion when co-cultivated with a wide variety of indicator cells, suggesting that HTLV envelope antigens interact with the membranes of many cell types. Serum antibodies from adult T-cell lymphoma-leukemia (ATL) patients inhibited the formation of syncytia, and sera from British, American and Japanese ATL patients inhibited cell fusion induced by American and Japanese HTLV isolates equally well. No serological cross-inhibition of syncytium induction was found between HTLV and bovine leukosis virus, Moloney murine leukemia virus and simian sarcoma-associated virus. A simple syncytium inhibition test in microtiter plates has been developed to provide a rapid screen for antibodies presumed to be specific to HTLV envelope glycoproteins.

Animals↗
PubMed1983

Single Na channels in mouse neuroblastoma cell membrane. Indications for two open states.

Single sodium channel currents were studied in mouse neuroblastoma cells. Channel conductance (gamma) was 11.6 +/- 3.4 pS at 6-8 degrees C. Unitary current amplitudes and channel activity increased with increasing temperature. The Arrhenius plot of the conductance was linear between 5 and 35 degrees C with an activation enthalpy of 27.1 kJ/mole (Q10 = 1.28). Amplitude distributions were fitted by the sum of two Gaussian functions indicating the presence of two different single channel amplitudes: smaller i1 and larger i2. The relative probability of appearance of i1, which has a shorter mean open time, was higher during the early phase of depolarization (t less than 16 ms). The open time histograms, inactivating phase of macroscopic currents and delay time histograms were fitted by the sum of two exponentials. The distinct kinetic and steady-state parameters reflect two open states of sodium channels.

Animals↗
PubMed1983

Alterations of the synaptosomal membrane 'microviscosity' in the brain cortex of rats during aging and centrophenoxine treatment.

Synaptosomal and myelin fractions were isolated from the brain cortex of young, adult and old male CFY rats (2, 12 and 24 mth, respectively). The purity of the fractions was tested by transmission electron microscopy and marker enzyme assays. The cholesterol content of the fractions was also determined. Samples of the fractions were labelled with diphenylhexatriene (DPH) and the fluorescence anisotropy (r) of the label was measured at various optical densities. The values of r extrapolated to zero optical density were compared in the age groups and used for calculating the 'microviscosity' of the membranes. The 'microviscosity' of synaptosomal membranes displayed a significant age-dependent increase: from 2.3 +/- 0.02 (SD) in the young group it increased to 2.6 +/- 0.03 poise by the age of 24 mth at 37 degrees C. Most of this increase occurred between the adult and old age. The cholesterol content of the synaptosomes also increased significantly during aging. Centrophenoxine (CPH)-treatment with 100 mg/kg body weight daily dose for 2 mth was able to reverse the age-dependent alterations of both the membrane 'microviscosity' and the cholesterol content in the synaptosomes: the values returned nearly to the adult level. The results obtained are interpreted in terms of the membrane hypothesis of aging attributing to primary role to the free-radical induced membrane damage in cellular aging.

Aging↗
PubMed1983

Effect of glutaurine on liver tumour development and acute leukaemia induced by MC29 virus in turkey poults.

The effect of glutaurine (gamma-L-glutamyl-taurine, Litoralon) on the take and development of hepatoma and acute leukaemia induced by MC29/L avian oncorna-virus has been investigated in turkey poults. Glutaurine significantly decreased the incidence of hepatoma, but had no significant effect on the lethality of MC29/L infected birds. The number of primitive myeloid cells was lower in the peripheral blood of glutaurine treated birds than in the untreated controls. Reverse transcriptase determinations in turkey fibroblast cell cultures indicated that glutaurine delays MC29/L virus expression.

Animals↗
PubMed1983

Results of space experiment program "Interferon". II. Influence of spaceflight conditions on the activity of interferon preparations and interferon inducers ("Interferon II").

The influence of spaceflight conditions on the biological activity of HuIFN-alpha preparations (lyophilized, in solution and in ointment) and interferon inducers was studied. In antiviral activity no difference was observed between the samples kept aboard the spaceship and the controls kept under ground conditions. The interferon inducers poly I:C, poly G:C and gossipol placed in the space laboratory for 7 days maintained their interferon-inducing capacity. The circulating interferon level in mice was the same irrespective of the induction being performed with flight or ground-control samples of inducers.

Animals↗
PubMed1982

Control of phosphatidylinositol turnover in adrenal glomerulosa cells.

The purpose of the present experiments was to compare the effects on phosphatidylinositol metabolism of agents stimulating aldosterone secretion. Glomerulosa cells, isolated from rat adrenals, were incubated in the presence of one of the following stimuli: angiotensin II, elevated potassium concentration, corticotropin, dibutyryl cyclic AMP and prostaglandin E2. Of all these substances, only angiotensin II stimulated the incorporation of [32P]phosphate into phosphatidylinositol. The effect was already detected 2.5 min and was still maintained 60 min after the onset of stimulation. A slight enhancement of the incorporation into other phospholipids was observed in the first minutes of stimulation. Cycloheximide abolished the effect of angiotensin II on aldosterone production, but not on phosphatidylinositol synthesis. In cells prelabelled with [32P]phosphate, radioactivity in phosphatidylinositol relative to that in other phospholipids decreased in response to angiotensin II within 5 min. This indicates that angiotensin II induces a specific breakdown of phosphatidylinositol. Corticotropin failed to enhance the incorporation of [32P]phosphate into phosphatidylinositol and other phospholipids in isolated fasciculate-reticularis cells. The results suggests that although both angiotensin II and potassium are presumed to act through changes in calcium metabolism, angiotensin alone generates the calcium signal by increased phosphatidylinositol turnover.

Adrenal Glands↗