Search PubMed⌕ Search

Biomedical subjects

D Beach

Publications and source records attributed to D Beach.

156 records · Page 9Linked to original sources
PubMed1980

Ovarian hyperstimulation in rats.

Induction of a mild hyperstimulation syndrome in the female rat, and the possible effect of the induction on prolactin, were studied using light and electron microscopy as well as radioimmunoassay. Five days of human menopausal gonadotropin (HMG) treatment were followed by human chorionic gonadotropin (HCG) administration. Ovarian hyperstimulation was observed in all treated rats, as attested to by the weight increase and by histological studies. Ovaries were enlarged 3-4 times as compared with controls, and consisted mostly of corpora lutea follicular cysts and hemorrhagic cysts. Other visceral organs remained unaffected, except for slight edematous changes observed in the lungs of the treated rats. Electron microscopic examination of the hypophysis of the treated group tends to indicate increased synthesis and secretory activity of the prolactin cells. However, serum prolactin levels of treated and non-treated groups were not different. Augmented doses of the gonadotropins did not change the findings, and only mild grade 2 ovarian hyperstimulation, according to Schenker and Weinstein (1978), could be produced in the mature rat. Thus, the rat experimental model does not seem to be comparable with the situation in the human, and cannot be used to study the pathogenesis of the disorder in the human.

Animals↗
PubMed1979

The pharyngeal effect of partial nasal obstruction.

The case histroy and cinematoradiographic findings of a baby with partial nasal obstruction are presented. This infant's restriction to air entry at the nose led to severe airway obstruction during inspiration by a forward movement of the posterior pharyngeal wall and backward movement of the tongue and lower jaw. At the height of inspiration, there was total airway occlusion in the pharynx. These events can be explained by the pressure drop that takes place behind a restriction if air is sucked through it forcibly from an area of atmospheric pressure. Studies of postpalatal pressures in adults and infants demonstrate such a drop in pressure during nasal breathing if the nose is partly obstructed. If the adult or infant is able to respond to the diminished nasal airway by mouth breathing, there is no postpalatal pressure drop. It is suggested that partial nasal obstruction in a sleeping obligatory nasal-breathing infant could result in a sucking back of the tongue over the larynx in this "cafe coronary" type of situation. This could be the mechanism of the obstructive type of apnea recorded by Steinschneider, and of the asphyxial type of death that is suggested by autopsies on some "cot death" victims. This hypothesis is consistent with the frequency of infection of rhinitis and pharyngitis in victims of sudden infant death syndrome and with the seasonal incidence. Prevention of this obstructive type of apnea would depend on the recognition of infants showing inspiratory and expiratory changes in pharyngeal airway size as can be seen externally by the movements in the carotid triangle of the neck and confirmed by roentgenography or cinematoradiography.

Adult↗
PubMedDate not supplied

Two new multi-purpose multicopy Schizosaccharomyces pombe shuttle vectors, pSP1 and pSP2.

Plasmids pSP1 and pSP2 are two new Schizosaccharomyces pombe ars1 multicopy vectors with the Saccharomyces cerevisiae LEU2 and URA3 genes as selectable markers. They are derivatives of S. cerevisiae integrative plasmids. These plasmids allow classical molecular genetic techniques, such as mutagenesis, nested deletions and sequencing, to be performed directly.

Cloning, Molecular↗
PubMedDate not supplied

Human cdc2 protein kinase is a major cell-cycle regulated tyrosine kinase substrate.

cdc2 is a catalytic subunit of a protein kinase complex, called the M-phase promoting factor, that induces entry into mitosis and is universal among eukaryotes. In HeLa cells, cdc2 is shown to be the most abundant phosphotyrosine-containing protein and its phosphotyrosine content is subject to cell-cycle regulation. One site of cdc2 tyrosine phosphorylation in vivo is selectively phosphorylated by pp60c-src in vitro.

CDC2 Protein Kinase↗
PubMedDate not supplied

Screening for antimitotic compounds using the cdc25 tyrosine phosphatase, an activator of the mitosis-inducing p34cdc2/cyclin Bcdc13 protein kinase.

A universal intracellular factor, the "M phase-promoting factor" (MPF), triggers the G2/M transition of the cell cycle in all organisms. In late G2, it is present as an inactive complex of tyrosine-phosphorylated p34cdc2 and unphosphorylated cyclin Bcdc13. In M phase, its activation as an active MPF displaying histone H1 kinase activity originates from the specific tyrosine dephosphorylation of the p34cdc2 subunit by the tyrosine phosphatase p80cdc25. We describe here a colorimetric assay of recombinant human cdc25A tyrosine phosphatase used as a cell cycle-specific target to screen for antimitotic compounds. The glutathione-S-transferase/cdc25A tyrosine phosphatase fusion protein is produced in large amounts of Escherichia coli and easily purified by affinity chromatography on glutathione-agarose. Optimal purification, storage and assay conditions (concentrations of enzyme, p-nitrophenylphosphate and dithiothreitol; duration of assay) have been determined. Using this system we tested 15 compounds currently used in cancer treatment; none of them displayed any inhibitory activity. However, the assay detected the inhibitory activity of vanadate, a reported tyrosine phosphatase inhibitor. The simplicity, speed and possible extensive automation of this assay using an essential cell cycle-regulating component provide a highly specific mechanism-based screen for antimitotic drugs discovery.

Amino Acid Sequence↗