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Biomedical subjects

J Neumann

Publications and source records attributed to J Neumann.

At least 307 records · Page 17Linked to original sources
PubMed1975

[Measurement of mean pulmonary pressures and right systolic ventricular pressure by radiocardiography].

Computer exploitation of some parameters of the radiocardiogram and of the pressures measured by catheterization in a series of 678 subjects, studied both in Paris and in Prague, has made it possible to establish regression equations providing the rates of mean pulmonary arterial and wedge pressures together with the systolic right ventricular pressure on the basis of the radiocardiogram data. The latter was obtained by the conventional technique of the isotope dilution curves or by gamma-angiocardiography. Easy repetition of radiocardiography makes it an interesting investigation for the haemodynamic follow-up of the patients with heart disease.

Barium↗
PubMed1973

The Relation between Photophosphorylation and Delayed Light Emission in Chloroplasts.

One millisecond delayed light emission has been studied in isolated coupled lettuce (Lactuca sativa var. romaine) chloroplasts. Delayed light emission was increased upon addition of ferricyanide or 2,3,5,6-tetramethyl-p-phenylene diamine. In the presence of ferricyanide, the magnitude of the signal was increased by the addition of ADP (in the absence of orthophosphate), ATP, DI0-9, or phlorizin. The signal was also increased by the addition of NaCl and by the addition of NH(4)Cl in the presence of a high NaCl concentration. The signal of delayed light emission was decreased by the addition of gramicidin, valinomycin, and by the addition of NH(4)Cl in the presence of a low NaCl concentration.Phosphorylation, whether started by addition of ADP or by addition of glucose plus hexokinase plus ATP, caused a significant decrease in delayed light emission. It was concluded that the magnitude of delayed light emission reflects the size of the proton motive force across the thylakoid membrane. Calibration of delayed light emission by creating KCl gradients indicated that the value for the electrochemical potential gradient for H(+) in the presence of ferricyanide was at least 155 millivolts decreasing to 134 millivolts after the onset of phosphorylation.

Journal Article↗
PubMed1973

Photosynthetic Reactions in the Marine Alga Codium vermilara: I. CO(2) Fixation and Hill Reaction in Isolated Chloroplasts.

Chloroplasts were isolated from the marine alga Codium vermilara (Siphonales). The isolated chloroplasts were active in CO(2) fixation in the light at a rate comparable to the rates obtained by fragments of thalli. Maximal rates of CO(2) fixation by isolated chloroplasts from Codium were obtained in the presence of salt or sorbitol isoosmotic with sea water. The conditions of isolation of Codium chloroplasts are much less stringent than those required for active chloroplasts from higher plants. The isolated chloroplasts comprise a homogeneous population of the intact "class I" type, as based on microscopic observations and on their inability to reduce ferricyanide unless osmotically shocked. The intact chloroplasts are able to reduce p-benzoquinone at a high rate.

Journal Article↗