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Biomedical subjects

J Breuer

Publications and source records attributed to J Breuer.

173 records · Page 10Linked to original sources
PubMed1967

Interrelationships between fatty acid biosynthesis and acyl-lipid synthesis in Chlorella vulgaris.

1. Fatty acid synthesis from [2-(14)C]acetate by Chlorella vulgaris cells grown and incubated in the dark is limited almost entirely to the production of saturated and monoenoic acids. 2. In light-incubated cells, both saturated and polyunsaturated fatty acids are rapidly synthesized. 3. Two groups of lipids can be distinguished in both dark- and light-incubated cells. The first group, consisting of phosphatidyl-glycerol, monogalactosyl diglyceride, lecithin and neutral glyceride, has a very high turnover rate for certain fatty acids. The second group, consisting of digalactosyl diglyceride, sulpholipid, phosphatidylethanolamine and phosphatidylinositol, has a slow turnover of fatty acids. 4. The lipids with rapid fatty acid turnover may be involved in the sequences of saturated and unsaturated fatty acid synthesis. A classification of lipids is made on the basis of their suggested functions.

Acetates↗
PubMedDate not supplied

Slice-selective fat saturation in MR angiography using spatial-spectral selective prepulses.

Presaturation of fat signals by frequency-selective radiofrequency (RF) pulses is often applied in MR angiography to improve the visualization of the blood vessels. Unfortunately, standard fat saturation methods might cause a considerable reduction of the blood signal in the measured slices. This effect is caused by an attenuation of blood magnetization in remote tissue regions with water protons showing a similar Larmor frequency as the fat protons in the recorded slice. The affected blood water protons subsequently flow into the recorded slice and provide low signal intensity. Suitable spatial-spectral selective methods for slice-selective fat saturation were developed to avoid this unwanted effect. A spatial-spectral fat saturation technique was compared with a corresponding only spectrally selective approach. Both saturation techniques were included in a standard two-dimensional (2D) cine sequence and applied in angiographic examinations of the thighs. The results indicate that spatial-spectral saturation (acting slice selectively) leads to a clearly higher blood signal intensity in fat-suppressed MR angiography compared with standard techniques, especially in measurements performed during the systolic phase of the cardiac cycle.

Adipose Tissue↗
PubMedDate not supplied

Increased turnover of serotonin in children with pulmonary hypertension secondary to congenital heart disease.

Serotonin (5HT) is a potent vasoconstrictor of the pulmonary vascular bed and may be involved in the pathophysiology of secondary pulmonary hypertension in children with a left-to-right shunt due to a congenital heart defect. To test this hypothesis we measured the total and free 5HT concentration in blood as well as the urinary excretion of its main metabolite 5-hydroxyindoleacetic acid (HIAA) in children showing a left-to-right shunt with (n = 10) and without (n = 18) pulmonary hypertension. 5HT and HIAA were also measured in children after corrective cardiac surgery using cardiopulmonary bypass (n = 14) and in controls without congenital heart disease (n = 18). The concentrations of total and free 5HT were not significantly different between controls and patients with a left-to-right shunt. After cardiac surgery total 5HT concentration was significantly reduced by about 65% owing to a postoperatively reduced platelet count. In patients with a left-to-right shunt the total 5HT content was similar in the right atrium (204.0 +/- 17.3 ng/ml), pulmonary artery (189.0 +/- 19.1 ng/ml), and aorta (195.0 +/- 19.3 ng/ml), as was the free 5HT concentration. Therefore no net release of 5HT from platelets occurred between these sampling sites. In patients with pulmonary hypertension, the urinary excretion of HIAA was significantly increased when compared with controls and patients without pulmonary hypertension. It is concluded that turbulent blood flow in children with a left-to-right shunt does not lead to a significant release of 5HT from platelets. However, the increased urinary excretion of HIAA in patients with pulmonary hypertension indicates an increased turnover of 5HT, probably due to an increased number of intrapulmonary neuroepithelial cells or a higher metabolic rate of 5HT within those cells.

Cardiopulmonary Bypass↗