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Biomedical subjects

J Raymond

Publications and source records attributed to J Raymond.

At least 235 records · Page 13Linked to original sources
PubMed1976

[Pathways and ascending vestibular projections emanating from primary nuclei: radioautographic study (author's transl)].

A study of the pathways and ascending vestibular projections was carried out in the cat after unilateral injection of tritiated leucine into the rostral vestibular complex. Radioautographic analysis revealed a gradual decline in the density of labeling as ascending fibers were found to progress towards more rostral relays. The pathways and projections were very compact in the oculomotor nuclei, became less intense in the Cajal and Darkschewitsch nuclei, and thinned out considerably until they reached a transitional zone in the thalamus between the ventrobasal and ventrolateral complexes. These results confirm established and previous findings in this laboratory obtained by neurophysiological and neurohistological examination procedures. They provide the first anatomical evidence concerning the existence of vestibulothalamic projections and pathways.

Afferent Pathways↗
PubMed1976

A vestibulothalamic pathway: electrophysiological demonstration in the cat by localized cooling.

Localized cooling was used in the search for vestibulothalamic pathways and a study was made of its effect on the activity of the thalamic neurons brought into action by stimulation of the vestibular nerve. Two cell populations were identified by their distinctive latencies in the ventral part of the posterior thalamus. Short latency responses were transmitted monosynaptically by means of a direct controlateral pathway whose course was identified. For long latency responses, the hypothesis of a polysynaptic path seems probable.

Animals↗
PubMed1976

[Cathepsin D from horse spleen. I. Purification and study of certain physicochemical properties].

Horse spleen cathepsin D (3.4.23.5.) was purified from crude extract by sodium chloride and ethanol precipitation, column chromatography fractionation on DEAE cellulose and CM Sephadex, re-chromatography on DEAE cellulose and gel filtration. The enzyme has been purified about 3.000 folds with a yield of 30 per cent. The purified enzyme seems to be homogeneous on Sephadex G100, one protein band is apparent on disc electrophoresis. Determined by dansylation the N-terminal amino acid is glycine. A molecular weight of 42,500 +/- 3,000 was obtained with Sephadex G100 gel filtration and light scattering measurements. Amino acid analysis and chemical determinations were performed: cathepsin D is a glycoprotein (2 or 3 osamine residues) including 344 amino acids and 4 disulfide bonds. Spectrophotometric data show that E1cm/1 mg/ml = 1.01 at lambda = 280 nm. ORD measurements indicate about 20 per cent of helicoidal content in the molecule.

Amino Acids↗
PubMed1976

[Cathepsin D from horse spleen. II. Study of certain enzymatic properties].

This work reports some enzymatic properties of highly purified horse spleen cathepsin D. Hydrolysis rate of several proteins are compared. The Kinetic constants (Km = 4.95 10(-5) M and Vm = 1,76 delta DO/mn/mug) have been determined in the presence of a denatured haemoglobin substrate. Stability of the enzymatic preparation is discussed according to the pH, concentration and time of storage. Some investigations concerning the active site are described. Enzymatic and chemical results show that dicarboxylic and tryptophanyl residues seem to be involved in the hydrolytic process. Catalysis does not depend on sulfhydryl or seryl residues. Different salts, particularly nitrate, nitrite and polyphosphate are potent inhibitors of enzymatic activity.

Animals↗
PubMed1976

Effects of source and concentration of thrombin, and divalent cations, on thrombin time of heparinized plasma.

The effects of the source and concentration of thrombin, and those of divalent cations, on the thrombin time (TT) of heparinized plasma were investigated. A correlation between TT and the heparin concentration was obtained only when the thrombin was of human origin and when it was reconstituted in divalent cation solutions. Relatively small variations in thrombin concentration resulted in marked differences in TT of heparinized plasma. Bovine thrombin gave a very prolonged TT of heparinized plasma compared with human thrombin, though the two thrombins gave identical TT's for non-heparinized control plasma. Divalent cation solution, in which thrombin was reconstituted, had a profound influence on TT of heparin plasma. When thrombin was reconstituted in 0.1 M MnCl2 solution, the TT of a plasma containing 0.5 unit heparin per ml. was the same as that of a plasma containing no heparin. The reliability of the thrombin time test as a means of monitoring heparin anticoagulation must be established by individual laboratories via extensive testing of clinical samples.

Animals↗
PubMed1976

Critical importance of citrate--blood ratio in platelet aggregation studies.

The effects of citrate concentration on adenosinediphosphate-, epinephrine-, collagen-, and ristocetin-induced human platelet aggregation were investigated. Relatively small increments in citrate concentration markedly inhibited platelet aggregation by all three physiologic agents. The inhibitory effect was greatest on epinephrine-induced aggregation, and least on collagen-induced aggregation. Ristocetin-induced aggregation was not affected by excess citrate anticoagulation. These findings indicate the importance of controlling the citrate:blood ratio in clinical platelet aggregation studies and in the assessment of antiplatelet drugs.

Adenosine Diphosphate↗
PubMed1976

Metal ion content of Escherichia coli versus cell age.

The potassium, calcium, magnesium, and zinc ion content of cells in exponential and synchronously growing cultures of Escherichia coli B/r was determined with an X-ray fluorescence spectrometer and an atomic absorption spectrophotometer. Cellular potassium, calcium, and magnesium content increased smoothly during the cell cycle, but cellular zinc showed a steplike increase about 10 to 15 min after cell division in a culture having a doubling time of 47 min. The possible role of cellular zinc in the control of cell division is discussed.

Calcium↗
PubMed1975

An absolute requirement for serum macromolecules in phytohaemagglutinin-induced human lymphocyte DNA synthesis.

We have examined the effect of different variables such as tissue culture media, with or without various supplements, lymphocyte isolation techniques, lymphocyte contamination by autologous red blood cells and platelets, and lymphocyte numbers, on the requirement for serum during phytohaemagglutinin (PHA) induced DNA synthesis in human lymphocytes. At all mitogen doses tested, we have found that dialysable constituents of serum enrich the ability of all tissue culture media to support lymphocyte DNA synthesis; however, human lymphocytes display an absolute requirement for nondialysable macromolecular constituents of serum in order to synthesize DNA.

Cell Separation↗