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Biomedical subjects

S Halpern

Publications and source records attributed to S Halpern.

At least 91 records · Page 5Linked to original sources
PubMed1986

Mitochondrial calcium and bone mineralization in the rat fetus.

The initial mineralization of the tibial bone collar of 17-day-old rat fetuses has been investigated. Images obtained after glutaraldehyde-paraformaldehyde-OsO4 fixation were compared to those obtained after K-pyroantimonate (PAO) fixation. Ca, P and Sb were identified and Ca/P intensity ratios evaluated by wavelength dispersive X-ray microanalysis. Alkaline phosphatase was detected on decalcified sections. Some osteoblasts showed degenerative changes and free mitochondria could be seen within the osteoid on the prolongation of their cytoplasmic processes. The mitochondria contained mineralized granules and clusters. Similar granules, numerous clusters and few matrix vesicles were observed within osteoid. The Ca/P intensity ratios (PAO fixed sections) of mitochondrial mineral (11.5 +/- 2.54) were different from the ratio of crystalline mineral in matrix vesicles (1.52 +/- 0.07). Alkaline phosphatase was present along plasmalemma of osteoblasts and around mineral deposits. These results show that in the rat fetus osteoblast mitochondria may be extruded from the cells, and that mitochondrial granules may represent the first mineral deposits in osteoid.

Animals↗
PubMed1985

Anaesthesia for caesarean section in a pre-eclamptic patient with Ebstein's anomaly.

Anaesthetic management for Caesarean section in a pre-eclamptic patient with Ebstein's anomaly and a right to left intracardiac shunt was accomplished under general anaesthesia. Air bubbles in the venous line were meticulously eliminated to prevent paradoxical air emboli. A rapid sequence induction using standard doses of thiopentone and succinylcholine did not result in loss of consciousness and muscle relaxation was inadequate for endotracheal intubation. This problem must be anticipated in patients with extremely enlarged right atria and the dose of induction agents should be increased. Carefully controlled epidural anaesthesia may be used if the cardiac reserve is adequate.

Adult↗
PubMed1984

Localization of zinc in the thymic reticulum of mice by electron-probe microanalysis.

Thymulin, a thymic hormone, is a nonapeptide requiring zinc for biological activity. It has been shown that epithelial cells, forming part of the thymic reticulum, secrete this hormone and/or store it within cytoplasmic vacuoles. X-ray electron-probe microanalysis (EPMA) has been used to detect zinc in the thymus. Low concentrations of zinc have been demonstrated in the dense granules contained in clear vacuoles of some epithelial cells in normal and ZnCl2-injected mouse thymuses, thus suggesting that the metal may be coupled to the peptide before the secretion of the hormone from the cells.

Animals↗
PubMed1984

Bone ultrastructure and x-ray microanalysis of aluminum-intoxicated hemodialyzed patients.

In hemodialyzed patients aluminum (Al) intoxication may induce osteomalacic lesions which are mainly observed when plasma immunoreactive parathyroid hormone (iPTH) concentrations are low, and osteitis fibrosa absent. In this study, the bone tissue of eight hemodialyzed patients with elevated plasma and bone Al concentrations was examined by histomorphometry, electron microscopy, and x-ray microanalysis. Five patients (group 1) had osteomalacia and minimal osteitis fibrosa, three patients (group 2) had severe osteitis fibrosa. In group 1, Al was concentrated at the mineralizing front, in hexagonal structures measuring 200 to 1,000 A which also contained phosphorus, but not calcium. Hydroxyapatite needles had a normal aspect. Osteoblasts appeared inactive. In group 2, Al was also present at the mineralizing layer of osteoid, but, in these cases, in small clusters next to abnormal calcium deposits. Osteoblasts appeared very active. Their mitochondria contained calcium and phosphorus granules, or amorphous material, measuring 1,500 to 2,000 A, emitting x-rays characteristic for Al and phosphorus. These results suggest that secondary hyperparathyroidism, by stimulating the cellular activity, may increase the uptake and release of Al by the osteoblasts. The presence of Al within the mitochondria of these cells may be one of the factors inducing the mineralization defect.

Adult↗
PubMed1984

In vitro biodegradation of chrysotile fibres by alveolar macrophages and mesothelial cells in culture: comparison with a pH effect.

The modification of the chemistry of asbestos chrysotile fibres (Mg3(Si2O5)(OH)4) after their ingestion by cultured cells has been studied. Two types of cells involved in asbestos related pulmonary disease were used, rabbit alveolar macrophages (AM), recovered by bronchoalveolar lavage, and pleural mesothelial cells (PMC) obtained from the rat parietal pleura. Chemical characterisation of intracellular fibres was performed on unstained ultrathin sections by electron probe microanalysis. The results showed a progressive leaching of Mg, characterised by a time dependent decrease of Mg/Si. AM were more efficient than PMC at leaching intracellular chrysotile fibres since it took longer to obtain the same proportion of leached fibres with PMC than with AM. As in vitro Mg-leaching can be obtained by acid treatment, chrysotile fibres were incubated, either untreated or pretreated with cell membranes, at pH 4 or 7 for various times. The data show that the kinetic of leaching by AM was comparable with leaching at pH 4. The leaching by PMC was of the same order as leaching at pH 7. When membranes were adsorbed on to the fibres, a delayed leaching was observed. The results indicate that the solubilisation of chrysotile by AM could be an intraphagolysosomal event due to a pH effect. With PMC, however, it is not possible to draw this conclusion since nothing is known about the intracellular pH.

Animals↗