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Biomedical subjects

M Laval

Publications and source records attributed to M Laval.

27 records · Page 2Linked to original sources
PubMed1977

Statistical study of a gamma camera transfer function.

In order to investigate the theoretical resolution of a gamma camera, the position transfer function of the input converters, scintillator and photocathode, has been studied. It is assumed that point scintillations occur in a scintillator at xy0 at a height h above a plane photocathode of sensitivity p per incident photon and that the spatial emission pattern of photoelectrons is known completely. A statistical analysis is given of various methods for determination of the estimator x0 of x0 both for a photocathode of finite and infinite extent. It is shown that the standard deviation sigma of this estimator x0 has a minimum value 2h/(N0p)1/2 where N0p/2 is the total number of photoelectrons emitted by the cathode.

Radionuclide Imaging↗
PubMed1977

[Hydrogen ion metabolism and parenteral alimentation].

The necessity of using solutions and emulsions in parenteral nutrition of solutions directly utilisable by the cell has led to the manufactur of substances with a composition and physico-chemical nature which greatly alters H+ ions balance. Theoretical calculation and various experimental protocois have shown that the production of H+ ions may be multiplied by 3 or 4. This explains the complications of metabolic acidosis seen in association with prolonged parenteral nutrition. There are two main sources : lipid emulsions and amino-acid solutions. One litre of lipid emulsion may provide 37 to 60 mEq of H+ ions. According to their formula, amino acid solutions may consume, or more often provide, large amounts of H+ ions (up to 20 mEq/gram of nitrogen). These physiopathological concepts should be taken into consideration in defining the compositions of fluids for parenteral nutrition, in particular when renal function is impaired.

Acidosis↗
PubMed1976

Incorporation of amino acids by rat liver nucleoli in vitro.

Isolated rat liver nucleoli are shown to incorporate radioactive amino acids into proteins. The characteristics of this nucleolar protein-synthesizine system indicated that the incorporation observed was not due to cytoplasmic or bacterial contamination. The products synthesized by isolated nucleoli have been analyzed by polyacrylamide gel electrophoresis and subsequent autoradiography; this revealed a few radioactive bands suggesting that in vitro only a few proteins are labelled. The results presented are discussed in view of a possible nucleolar protein synthesis.

Amino Acids↗