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Biomedical subjects

D Samuel

Publications and source records attributed to D Samuel.

At least 289 records · Page 16Linked to original sources
PubMed1978

Effect of maternally administered sodium nitrite on hepatic erythropoiesis in fetal CD-1 mice.

A commonly used food preservative, sodium nitrite, was administered to pregnant CD-1 mice at a concentration of 0.5 mg/mouse/day. Embryotoxic and teratogenic effects on the hemopoietic tissues and skeletons of their offspring, were evaluated. Fetal mortality, resorptions, the mean number of offspring per litter, the mean weight per embryo and the incidence of skeletal malformations, were not significantly different from controls. Hemopoietic cell suspensions, prepared from the livers of treated and control 14-, 16- and 18-day embryos, were cytocentrifuged onto microscope slides and differential counts were performed after staining with benzidine and Wright-Giemsa stain. The results indicate that maternally administered Na nitrite, stimulates fetal hepatic erythropoiesis. This was manifested in a statistically significant increase in the percentage of polychromatophilic erythroblasts and mature erythrocytes at 14 and 16 days of gestation, respectively. The possibility that Na nitrite may induce fetal methemoglobinemia is discussed and mechanisms responsible for the observed erythroid stimulation, are considered.

Animals↗
PubMed1977

[Deep hypothermia on the infant: physiopathology and technics of ECC].

In 81 operations for correction of infants's cardiopathies, authors used, associated with E.C.C., a deep hypothermia allowing a circulatory arrest of an average duration of 52 minutes, according to the technics described by BARRAT-BOYES in 1971. From this experience, authors study the modifications brought to the organism by this hypothermia, and discuss the technical aspects in pre, per and post-operative periods. Mortality of this series is of 13,5 p. 100. It is in relation with the cardiopathy or it's correction, without anu possibility or directly charge the technique of hypothermia in its determinism. The early mortality includes a bilateral phrenic paralysis, an air embolism, three septic complications and two neurologic complications probably related to a poor thermic repartition. Advantages of this technique concern the possibility to operate in a bloodless field and a diminution of E.C.C. time.

Coronary Vessel Anomalies↗
PubMed1976

The effect of antisynaptosomal plasma membrane antibodies on memory.

Antisynaptosomal plasma membrane antibodies were introduced through an infusion cannula into rat brain and their effects on behaviour were tested. Four different learning paradigms were used, two appetitively and two aversively motivated, to show impairment in memory retrieval. No effects were found on aquisition, motor activity, or motivation.

Animals↗
PubMed1976

Uptake and metabolism of fatty acids and analogues by cultured cardiac cells from chick embryo.

Cultured heart cells from chick embryo, present as a confluent monolayer in a minimal medium, take up labelled fatty acids (from C6 to C22) bound to serum albumin with a rapid incorporation into neutral and complex lipids (visible at 15 s), while beta-oxidation is delayed (visible at 15 min). Fatty acids enter the cardiac cells through two mechanisms, one involving a readily saturable process, the other resembling passive diffusion. The saturable transport system recognizes fatty acids with a high affinity, Km from 4.5 to 16 muM. The V is from 0.03 to 0.3 nmol of fatty acid incorporated min-1 (10(6) cells)-1. Competitive inhibition occurs between fatty acids while glucose, aminoacids and lactate do not compete with palmitate for the entry into the cells. The analysis of unesterified fatty acids from the usual culture medium and from the cells show a gradient of concentration up to 54-fold; moreover experiments performed in minimal medium at 20 degrees C show that fatty acids accumulate up to 28-fold in the cells. Efflux rates can be measured after loading the cells at 20 degrees C; the curves are bimodal and the pseudo first-order rate constants thus determined are in the order of 0.5 min-1, as opposed to 2.5 to 5.0 min-1 for the passive-diffusion component calculated for the influx rates. Studies on the role of serum albumin at constant and at variable fatty acid-albumin molar ratios indicate that the rate of uptake is controlled by the total fatty acid concentration and not solely by the concentration of unbound fatty acids. No labelled fatty acid was found to be bound to the cytoplasmic fraction supposed to contain the fatty acids-binding protein; our results are in favour of the presence of a specific transport system for fatty acids either at the level of subcellular organelles or more likely at the surface of cardiac cells.

Animals↗
PubMed1976

Effect of lithium and other alkali metals on brain chemistry and behavior. II. Intracranial self-stimulation behavior.

Rats implanted with bipolar electrodes aimed at the medial forebrain bundle (MFB) were trained to self-stimulate. Six daily injections of 2 mEq/kg of the chloride salts of Li+, Rb+ or Cs+ were administered and the rate of intracranial self-stimulation (ICSS) was recorded. Lithium caused a reversible decrease in ICSS rate, beginning on the second day and returning to pretreatment rate on the fourth day of injections. The decrease was more pronounced in animals with high baseline rate (over 500 responses/10 min) than in low responders. Rubidium enhanced ICSS rate whereas cesium had no effect. These results agree with other accumulating data showing the opposite effects of Li+ and Rb+, but their relevance to effective disorders is not clear.

Affective Symptoms↗
PubMed1976

The effects of dark isolation on the performance of a white-black discrimination task in the rat.

Four experiments were performed on rats using a white-black discrimination task. In Exp. 1 the animals that were isolated in darkness for four hours after each learning trial performed with fewer errors than the animals that spent the same posttrial periods in enriched environments in groups. In Exp. 2 training was carried further and retention after 10 days was investigated. The isolated animals again performed with fewer errors. In Exp. 3 a control was added to the Isolated and Enriched conditions. Animals in the control group were returned to their home cages after each training trial. No difference was found between Enriched and Control animals. In Exp 4 Dark-Isolated, Light-Isolated, Dark-Crowded and Light-Crowded groups were used. The performance of the two Dark-treated groups was superior to that of the Light-treated groups. The findings are discussed with reference to interference and consolidation theory.

Animals↗
PubMed1975

In vivo measurement of 32P in the brain of a freely moving rat.

A new method for measuring the uptake of materials labeled with radioactive phosphorus (32P) in the brain of a freely moving rat is described. The rate of uptake in the brain of a single animal of 32P-labeled phosphate was compared to the uptake rate in the animal's blood or liver. A comparison was made between the uptake following an intravenous (IV) or an intraperitoneal (IP) injection. The effect of convulsions caused by injections of metrazol on the kinetics of 32P uptake in the brain is described.

Animals↗