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Biomedical subjects

R Allen

Publications and source records attributed to R Allen.

At least 199 records · Page 11Linked to original sources
PubMed1987

Bombesin alters the sympathetic nervous system response to cold exposure.

The accumulation of dopamine in interscapular brown fat, heart, kidney and mesenteric white fat has been used as an index of sympathetic nervous activity in rats in which dopamine beta-hydroxylase has been blocked. Intracerebroventricular administration of bombesin impaired the cold-induced increase of dopamine accumulation in interscapular brown fat but not in other tissues. These studies provide evidence that bombesin acts within the central nervous system to modify efferent sympathetic nervous system responses to cold exposure in a viscerotopically specific manner. This action of bombesin is consistent with the other central nervous system actions of this peptide, i.e. inhibition of heat production and disruption of thermoregulation.

Adipose Tissue, Brown↗
PubMed1987

Optic nerve dysfunction during gravity inversion. Visual field abnormalities.

Inversion in a head-down position (gravity inversion) results in an intraocular pressure of 35 to 40 mm Hg in normal subjects. We used computerized static perimetry to measure the visual fields of normal subjects during gravity inversion. There were no visual field changes in the central 6 degrees of the visual field compared with the baseline (preinversion) values. However, when the central 30 degrees of the visual field was tested, reversible visual field defects were found in 11 of 19 eyes. We believe that the substantial elevation of intraocular pressure during gravity inversion may pose potential risks to the eyes, and we recommend that inversion for extended periods of time be avoided.

Adult↗
PubMed1986

Productive language of premature and physically handicapped two-year-olds.

Structural and functional features of the productive language of healthy and at-risk 2-yr-olds were compared. Subjects were normal, full-term toddlers (n = 15), toddlers with either cosmetic or orthopedic anomalies (n = 15), and premature toddlers (n = 15). Transcripts of the language of each child were compiled from 30-min videotapes of mother and child engaged in a variety of semistructured activities. Although premature and physically handicapped toddlers did not differ significantly from each other, both groups of medical risk toddlers were delayed in a variety of structural indices of their productive language. In comparison to normal children, they had a shorter MLU and upper bound, and a smaller vocabulary, including fewer verbs. On functional features of language usage, however, there were few differences between normal and high-risk toddlers. Results are discussed in the context of developmental and learning models that posit a relationship between maternal and child behavior.

Child Language↗
PubMed1986

Reduction of infection after cardiac surgery: a clinical trial.

Between January 1, 1975, and June 1, 1984, 3,275 patients underwent cardiac operations with cardiopulmonary bypass. No operations were performed in 1978. In Phase I of the study, general operating rooms were used for cardiac operations, and standard methods of antisepsis and asepsis were used. Phase II began in January, 1979, with the opening of two specially constructed operating rooms with complete separation of incoming and outgoing personnel and supplies, and with a laminar airflow system. All personnel scrubbed 3 minutes and changed into autoclaved clothing before entering the operating suite, and scrubbed again for 5 minutes before putting on gowns. By Phase III, which began in July, 1982, all additional protocols against infection were in place including strict techniques in the intensive care unit and a continuous antiinfection surveillance program. In Phase I, 7.3% (70% confidence limits [CL] 6.4 to 8.2%) of patients had an infectious complication; in Phase II, 2.7% (CL 2.3 to 3.2%), and in Phase III, 0.8% (CL 0.5 to 1.2%). The reductions were similar in the four subtypes of infection (superficial presternal infection, mediastinitis, endocarditis, and septicemia). The study indicates that improving the surgical environment, improving the surgical and operating room protocols, and increasing the awareness of the dangers of infection among the personnel can strikingly reduce the incidence of infections after cardiac operations.

Bacterial Infections↗
PubMed1986

Organization of cytokeratin bundles by desmosomes in rat mammary cells.

In a rat mammary epithelial cell line, LA-7, cytokeratin bundles recognized in immunofluorescence by a monoclonal antibody (24B42) disappear after trypsinization of cultures and are gradually reformed after replating. We have followed the time course of cytokeratin filament reappearance by growing cells in low calcium medium (0.1 mM) which prevents desmosome formation, and then shifting to high calcium (1.8 mM) to start the process. By fixing the cells at various intervals and staining them in immunofluorescence for 24B42 cytokeratin and for desmosomal proteins, we found that cell to cell contact and desmosome formation are prerequisites for keratin filament formation in these cells. EGTA treatment, by disassembling desmosomes, causes the cytokeratin filaments to disappear and the 24B42 protein to pass into a soluble form in this cell line, as ascertained by 100,000 g fractionation and immunoenzymatic assay. Cycloheximide treatment also causes cytokeratin filaments to disappear, indicating that protein synthesis is needed for normal filament maintenance. In another related cell line (106A-10a) and in HeLa cells, trypsinization and EGTA exposure do not cause a complete loss of 24B42 immunofluorescence, although distinct filaments disappear, indicating the presence in these cells of different organizing centers, besides desmosomes, for cytokeratin bundle formation. LA7 cells therefore seem to have a cytokeratin system strictly dependent on the presence of desmosomes, which act as an organizing center for filament assembly. 106A-10a cells (also rich in desmosomes) and HeLa cells (showing instead a reduced number of desmosomes) have a cytokeratin system partially or totally independent from that of desmosomes, with different organizing centers.

Animals↗
PubMed1985

The significance of meconium in midtrimester genetic amniocentesis.

Since the advent in recent years of midtrimester amniocentesis for genetic testing, there has been an increasing number of reports of occasional instances of meconium-stained amniotic fluid of uncertain prognostic significance. Previous reports have suggested a fetal mortality of 30%. With larger series now available for study, more accurate information on the incidence of this occurrence and its significance is presented. The present series consists of 4709 consecutive amniocenteses performed from 1978 to 1983, at two genetic testing centers in Portland, Oregon. Meconium-stained amniotic fluid was found in 79 cases, for an incidence of 1.67%. Contrary to previously published reports, the fetal mortality was 5.06%. Thus the finding of meconium-stained amniotic fluid during midtrimester genetic amniocentesis may not carry the ominous prognosis that originally might have been predicted.

Adult↗