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Biomedical subjects

Y Cohen

Publications and source records attributed to Y Cohen.

At least 415 records · Page 23Linked to original sources
PubMed1976

[Effect of normobaric and hypobaric hypoxia on norepinephrine turnover in the rat heart (author's transl)].

1. After administration of 3H norepinephrine (NE), the turnover rates of NE were determined by the decrease in radioactivity. 2. Rats were housed by groups in chambers and either maintained as controls or exposed to a hypoxic environment (PIO2 = 90 torr). The turnover rates of NE were not altered by normobaric hypoxia (fig. 1, table I). 3. Hypobaric hypoxia (barometric pressure was reduced to 500 mm Hg and PIO2 was 105 torr) increased the turnover rates of NE (fig. 2, table II). 4. The role of the sympathetic nervous system during exposure to hypoxia in Rats is discussed with regard to functional adaptation.

Adaptation, Physiological↗
PubMed1976

[Pharmacokinetics of DL-norephedrine 14C in the rat].

After i.v. administration of DL-norephedrine 14C to the rat (535 mug/kg), approximately 75% of the radioactivity was eliminated during the first 18 hr in the urine. Beside the unchanged drug (71.5% of the total urinary radioactivity), the main metabolite was alpha-methyloctopamine (18%), a parahydroxylated derivative of which 68% were excreted as glucuronide conjugates. Kinetic studies of DL-norephedrine in different organs showed that the affinity of tissues for the amine did not change with time. Captation was important and rapid in lungs, adrenals, spleen and heart. The brain was marked by a slow increase of drug level during the first 2 hr. However, the terminal semi-exponential kinetic slopes of DL-norephedrine concentration showed that the elimination processes of the drug were the same in each tissue. The affinity of tissues for alpha-methyloctopamine was shown to be much more specific; its uptake was higher in organs which are rich in adrenergic nerve endings (heart, adrenals and spleen). These results confirm the role of this hydroxylated amine as a false neurotransmitter. A whole body autoradiography in the mouse showed an important uptake of DL-norephedrine 14C in salivary glands and periocular structures.

Animals↗
PubMed1975

[Comparative subcellular localization of para-hydroxylated derivatives of ephedrine and amphetamine in rat brain].

Localisation of noradrenaline, hydroxyamphetamine, hydroxynorephedrine and hydroxyephedrine was studied in adrenergic granules of rat's brain in normal animals and in animals injected with hydroxy-6 dopamine. In normal animals the synaptosomes fixed noradrenaline, first and then, in decreasing order, hydroxynorephedrine, hydroxyephedrine and hydroxyamphetamine. Hydroxy-6 dopamine injection resulted in a decrease of fixation by synaptosomes, thus confirming the role of central false-transmitters of hydroxylated derivatives of amphetamine and ephedrine.

Amphetamines↗
PubMed1975

A preliminary report on the effects of methanol extraction residue of BCG (MER) on cancer patients.

Twenty-seven patients with malignant neoplasia were injected intradermally with the methanol extraction residue (MER) fraction of tubercle bacilli. Two schedules of treatment were used: every other week and once a month; 1-10 courses of MER were administered to the patients. The skin reactivity to 3 recall antigens, as well as to the injected MER itself, was used to monitor the immune response. Improvement of skin reactivity occurred in 9 of 18 patients tested with recall antigens. Five of 6 patients treated every other week improved in their immune capacity whereas only 4 of 12 patients improved on the monthly schedule. Thus, repeated injections given every other week were more effective in increasing the cutaneous reactivity than monthly injections of MER. The side-effects of MER treatment were tolerable.

Antigens, Bacterial↗
PubMed1975

Facultative anoxygenic photosynthesis in the cyanobacterium Oscillatoria limnetica.

An isolate from H2S-rich layers of the Solar Lake, the cyanobacterium Oscillatoria limnetica, exhibits both oxygenic and anoxygenic photosynthesis. It can use Na2S as an electron donor for CO2 photoassimilation (photosystem I supplies the energy) in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea or 700-nm light. A stoichiometric ratio of approximately 2 is observed between the Na2S consumed and the photoassimilated CO2. The anoxygenic phototrophic capability of this cyanobacterium explains its growth in nature in high sulfide concentrations and indicates a selective advantage.

Aerobiosis↗
PubMed1975

[Blood-brain barrier. II. Kinetics of distribution of 3H-parahydroxyamphetamine in brain structures after intravenous administration in the rat].

Intravenously injected parahydroxyamphetamine hardly penetrates into the Central Nervous System, since, 5 minutes after injection, the tissue to plamsa concentration ratio for brain and cerebrospinal fluid amounts to 0,67 and 0,35 respectively. Its concentration in muscle is 5 times higher than in plasma. In the brain, the molecule is preferentialy taken up by the corpus striatum and the hypothalamus. Thus, parahydroxylation of amphetamine inhibits the penetration of the molecule into the brain and suppresses its cortical fixation. These characteristics could explain why this parahydroxylated amine has no psychotropic action.

Amphetamines↗
PubMed1975

[Accumulation of ephedrine, norephedrine, amphetamine and tyramine labeled with carbon 14 in pigmented and non-pigmented eyes in two races of rats].

The pigmented eyes of non albino rats (PVG) accumulated ephedrine, norephedrine and amphetamine. After 15 min accumulation of ephedrine and amphetamine was larger than of norephedrine. Autoradiographic studies showed that accumulation occurred in melanin containing iris and choroid and also in lacrymal glands which lack melanin. Accumulation of tyramine did not occur in eyes containing melanin. The non pigmented eyes of albino rats did not accumulate ephedrine, amphetamine, norephedrine and tyramine. It appeared that in pigmented eyes melanin was a site of loss of ephedrine, amphetamine and norephedrine; hence a smaller amount of drug will be available for interaction with adrenergic neurons and a smaller mydriatic effect will occur. Accumulation is possible only when metabolism is low, as observed with alpha-methylated amines. The four sympathomimetic amines used did not accumulate in the pigmented skin of black and white rats.

Amphetamine↗