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Biomedical subjects

G Nagy

Publications and source records attributed to G Nagy.

At least 163 records · Page 9Linked to original sources
PubMed1986

Separation and suckling-induced changes in serum growth hormone levels of lactating rats and their pups.

The effects of separation and suckling on serum growth hormone (GH) levels of lactating rats and their pups were studied on days 1-3 of lactation. The litter size was adjusted to 8 pups/dam without respect to sex. The separation of pups from their mother for 5 h resulted in significant decrease in GH level in the pups. After 30 or 60 min of suckling the level of GH in serum of the pups reached the values of the control group, i.e. non-separated pups. If the pups were attached to pre-suckled mothers, thus consuming less milk, their serum GH levels increased in a significantly lesser extent. It is concluded that some factor(s) are present in milk which stimulate(s) GH secretion of the pups. Due to episodic secretion, high standard error occurred in every group of mothers studied. Mean GH level of freely behaving lactating rats were rather constant. On the other hand, the 5 h separation period and 30 min of suckling seemed to result in decrease and increase in serum GH values, respectively. By the end of a 60 min suckling period, GH declined to low levels again, hence it is likely that the separation and suckling stimuli synchronized GH-episodes. When the litter was replaced with hungry foster pups at 30 min of suckling, GH-decay by 60 min appeared to be less consequent.

Animals↗
PubMed1986

Data suggesting that milk of early lactation period might be involved in sexual differentiation of rat brain.

The contribution of a hypothetic milk factor in the masculinization process of gonadotropin secretion pattern was investigated using a cross-fostering model. Adult female rats whose nipples had been previously excised were mated. At the time of delivery their pups were given to recipient dams that had given birth one week earlier. Pups remaining with their own (intact) mother served as control group. At the age of 37-39 days (birth = day 0) male rats from the experimental and the control groups were castrated and also control females were ovariectomized. Ten days later gonadectomized animals received ovarian grafts excised from 20-day-old rats. Four and seven days after transplantation the grafts were processed for histology. Corpus luteum formation suggests that male rats nursed by recipient dams did not undergo the masculinization process normally occurring during the first few days of postnatal life. In a separate experiment, male pups nursed by dams being at the early lactation (control) or at the midlactation period were decapitated on postpartum day 1 and serum testosterone levels were measured by RIA. Mean testosterone concentration was almost twice as high in the control group than in pups nursed by recipient dams of the midlactation period. These data suggest that milk of the early lactation period might be necessary for the normal masculinization process of the male rat.

Animals↗
PubMed1985

Effect of CO2 on a brain extracellular space marker and evidence of its neuronal modulation.

Increases in inspired CO2 consistently altered the local concentration of the brain extracellular space marker alpha-naphthalene sulfonate (alpha-NS) as measured with ion-selective micropipettes in the rat thalamus. Stereotaxic injection of lidocaine in the region of the locus coeruleus attenuated this effect of CO2, and amitriptyline, a tricyclic anti-depressant and amine reuptake inhibitor, potentiated the effect. These results suggest that metabolic demand, as mimicked here by the addition of CO2, alters the fluid environment of the brain and central noradrenergic mechanisms may modulate this response.

Amitriptyline↗
PubMed1985

Simultaneous monitoring of voltammetric and ion-selective electrodes in mammalian brain.

A new technique of simultaneously recording from ion-selective and voltammetric microelectrodes in vivo allows one to measure concomitant ionic and monoamine neurotransmitter fluxes in the extracellular fluid space of the brain. Examples are presented of the results obtained with various drug and stimulus applications. The time correlations of the ionic and neurotransmitter fluxes are especially useful in attempting to better understand the possible interactions of these chemical dynamics with neuronal functioning.

Animals↗
PubMed1985

Diffusion coefficients of neurotransmitters and their metabolites in brain extracellular fluid space.

Diffusion coefficients of catecholamine neurotransmitters, their metabolites and related species was measured in brain extracellular fluid using in vivo voltammetric techniques. Nanoliter volumes of the species were pressure-ejected into the rat caudate nucleus and their concentration profiles were determined at nearby voltammetric detector electrodes. Thorough testing was carried out to show that the present methodology gave results which agreed with brain diffusion coefficients measured previously by ion-selective microelectrode techniques. All of the species which are anionic at pH 7.4 have brain diffusion coefficients about one-third of their solution counterparts in accord with earlier studies of diffusion in tortuous media. However, the brain diffusion coefficients of all the cation species are about three-times slower than those of the anions. This phenomenon is believed to be caused by ion binding with the polyanionic glycosaminoglycans and related species in brain tissue. In vitro model experiments lend support to this interpretation. This new information on biogenic amines and their metabolites provides meaningful predictions of the spatio-temporal concentration distribution of these species in the extracellular fluid.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1985

Screening for colorectal cancer in a Hungarian county.

An initial screening for colorectal cancer in asymptomatic adults was performed with Haemoccult in 26,357 persons, rigid rectoscopy in 10,673 and flexible sigmoidoscopy in 3,963 persons. The rate of cancer detection was 4.4% in screenees with a positive Haemoccult test, 0.08% using rigid rectoscopy and 0.28% using flexible sigmoidoscopy. The respective frequency of patients discovered to have polyps was 16.2%, 1.32% and 8.49%. 77% of the 36 colorectal cancers detected due to the Haemoccult test program were either Dukes A or B. A comparison of these screening results indicates that Haemoccult screening markedly increases the yield of colorectal neoplasms when asymptomatic persons are examined. This screening should be repeated annually to reduce the morbidity and mortality of colorectal cancer.

Adenoma↗
PubMed1985

Therapeutical experiments in ulcerative colitis and Crohn's disease.

In the period 1963-82 among the patients with aspecific inflammatory bowel disease, the incidence of ulcerative colitis was 3.1 per 100 000 per year, while the frequency of Crohn's disease has doubled during the observation period and now its incidence is 0.58 per 100 000 per year. During the past 20 years, 404 patients with ulcerative colitis were treated. The average follow-up of the patients lasted for 6.6 years. During this period, 40% of the patients could be kept in balance permanently with salicylazosulfapyridine (SASP) monotherapy. A further 34% reacted to SASP plus steroid. The rate of regression was increased by a further 14% when the combination was occasionally completed with a short-term antibiotic or prolonged azathioprine therapy. The inestimable cases and those refractory to treatment made up the other 12% and among them are also the 23 colectomized patients. During the two decades 40 patients with Crohn type ileocolitis were treated. SASP administration by itself was sufficient in only one case among them. In 6 cases steroid, in 4 antibiotics, in 7 azathioprine and in 2 cases metronidazole treatment had to be introduced complementarily. The fact that 21 of the 40 patients had to be subjected to bowel resection in some phase of the disease, shows how impossible it is to evaluate the different therapeutic interventions.

Azathioprine↗
PubMed1984

Nafion-coated electrodes with high selectivity for CNS electrochemistry.

A major improvement in the selectivity of small graphite electrodes used for in vivo electrochemistry is described. The electrodes are coated with Nafion, a perfluorosulfonated polymer. This coating is practically impermeable to ascorbic acid and anionic biogenic amine metabolites and only slightly responsive to neutral metabolites. Thus it becomes selective for the cationic primary neurotransmitters, dopamine, norepinephrine and 5-hydroxytryptamine. Responses of Nafion-coated and untreated electrodes in vivo are compared.

Animals↗