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Biomedical subjects

R Dennis

Publications and source records attributed to R Dennis.

12 recordsLinked to original sources
PubMed1992

Insect glial cells show differential expression of a glycolipid-derived, glucuronic acid-containing epitope throughout neurogenesis: detection during postembryogenesis and regeneration in the central nervous system of Tenebrio molitor L.

The monoclonal antibody CAF-1 recognises a glucuronic acid-containing epitope present on insect acidic glycolipids. Immunohistochemical analysis of the CAF-1 epitope has revealed its differential, temporal and spatial expression during postembryogenesis of the midbrain of Tenebrio molitor. Electron microscopic resolution demonstrated, that the CAF-1 epitope is expressed on glial cells that ensheath the glomeruli of the central body. Concomitantly, a differential pattern of expression was observed in the ventral nerve cord, exhibiting a serially homologous display on glial cells that ensheath neuronal somata in the cell body layer of the thoracic ganglia and ventral associative neuropil. Prominent, topologically restricted CAF-1 immunoreactivity was monitored in termination areas of sensory neurons in the ventral associative neuropil and corresponding nerves 6-48 h after extirpation of the respective sensory neuron somata. CAF-1 expression is correlated with structural reorganisation in postembryonic nervous tissue of T. molitor.

Animals↗
PubMed1992

Cultural change and the reproductive cycle.

What we regard as 'normal' or 'natural' with respect to human female reproductive physiology differs greatly from the reproductive cycle experienced during most of human existence. Frequent ovulatory menstrual cycles really represent repeated abortive reproductive cycles and are unphysiological. A number of medical conditions, some of great importance, are the result of this change in the character of the reproductive cycle. Suppression of the menstrual cycle offers a means of decreasing the incidence and severity of these medical conditions.

Animals↗
PubMed1992

Differential regulation of prostaglandin E2 synthesis and phospholipase A2 activity by 1,25-(OH)2D3 in three osteoblast-like cell lines (MC-3T3-E1, ROS 17/2.8, and MG-63).

Both 1,25-(OH)2D3 and prostaglandin E2 (PGE2) stimulate alkaline phosphatase activity in MC-3T3-E1 cells. Previous studies, demonstrating a correlation between 1,25-(OH)2D3-dependent alkaline phosphatase and phospholipase A2 activities in matrix vesicles isolated from growth cartilage chondrocyte cultures, suggest that one mechanism of vitamin D action may be via autocrine or paracrine action of PGE2. Since most PGE2 is derived from arachidonic acid released by the action of phospholipase A2, we examined whether 1,25-(OH)2D3 stimulates phospholipase A2 activity in three osteoblastic cell lines: ROS 17/2.8 cells, MC-3T3-E1 cells, and MG-63 cells. 1,25-(OH)2D3-dependent alkaline phosphatase and phospholipase A2 activity were correlated with production of PGE2 and PGE1 in the MC-3T3-E1 cells. Alkaline phosphatase specific activity was enriched in the matrix vesicles produced by all three cell types and was stimulated by 1,25-(OH)2D3 at 10(-8) to 10(-7) M. Although phospholipase A2 specific activity was enriched in the matrix vesicles produced only by the ROS 17/2.8 cell cultures, stimulation of this enzyme activity was observed only in the MC-3T3-E1 cell cultures. The effects of 1,25-(OH)2D3 on phospholipase A2 were dose-dependent and were significant at 10(-8) to 10(-7) M. There was a significant increase in PGE2 production in the MC-3T3-E1 cell cultures only. Indomethacin reduced PGE2 production to base line values. Even at baseline, MC-3T3-E1 cells produced ten times more PGE2 than did the ROS 17/2.8 or MG-63 cell cultures. The effects of 1,25-(OH)2D3 on PGE1 were comparable to those on PGE2.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1992

Vesico-diverticular fistula: a rare complication of Meckel's diverticulum.

Enterovesical fistulas usually result from diverticulitis, Crohn's disease, or colorectal cancer. A perforated Meckel's diverticulum can also result in an vesico-diverticulum fistula, as noted in three previously reported cases. In all three cases, bladder or bowel disease was associated with the fistula. Herein, the authors describe a previously healthy, 23-year-old man who presented with an enterovesical fistula. Exploratory laparotomy revealed a vesico-diverticular fistula resulting from a perforated Meckel's diverticulum. Pathologic examination revealed that the diverticulum did not contain ectopic gastric or pancreatic tissue and that the perforation was secondary to an enterolith. The patient underwent a diverticulectomy and had an uneventful postoperative course. Unlike any of the three previously reported cases, the authors' patient had no coexisting bowel or bladder disease occurring with his vesico-diverticular fistula. To the authors' knowledge, this is only the third reported case of a vesico-diverticular fistula resulting from a perforated Meckel's diverticulum that did not contain ectopic tissue. It represents the first case where the perforation was secondary to an enterolith.

Adult↗
PubMed1991

Activity disc and cage for continuous measurement of running activity and core temperature in hamsters.

We describe a design for the modular horizontal activity disc and tandem cages suitable for continuous monitoring of spontaneous running and of core temperatures in golden hamsters. An acrylic disc is equipped with a short brass axle. It is mounted inside a brass rotation sleeve at a 15 degrees angle off the horizontal plane. The disc module fits firmly inside either half of the tandem cage when activity measurements are needed. Easy removal allows for alternative use of cages. Minor modifications of disc dimensions and of disc base permit the use of activity modules with juvenile hamsters. The short distance between disc surface and cage floor permits continuous measurement of core temperature as well as running activity.

Animals↗
PubMed1978

Demonstration of an ecdysteroid receptor in a cultured cell line of Drosophila melanogaster.

Incubation of the high-speed supernatant from the Kc cell line of Drosophila melanogaster with [3H]ponasterone A results in significant binding of the ligand as determined by gel filtration and dextran-coated charcoal binding assays. In vivo exposure of the Kc line to [3H]ponasterone A for 30 min results in a marked binding of the ligand by a KCl-soluble nuclear extract. With both the cytosol and nuclear preparations the binding has specificity and a low dissociation constant (3 X 10(-9) M). In addition the labeling of the nuclear preparation exhibits a saturation at approximately 7 X 10(-10) M which probably reflects the molar concentration of cytoplasmic receptors.

Binding, Competitive↗
PubMed1975

Evidence of respiratory tract infection induced by equine herpesvirus, type 2, in the horse.

Five horses were experimentally exposed to equine herpesvirus 2 strain LK. Two young foals developed chronic pharyngitis (98 and 232 days, respectively). Growth characteristics, cytopathic effects (CPE), inclusion body formation, ether sensitivity, and immunofluorescent analysis indicated that the virus recovered from infected animals was a herpesvirus serologically identical with, or at least antigenically related to EHV-2 strain LK. No significant complement-fixing (CF) or virus-neutralizing (VN) antibody responses were observed in adult horses while both foals demonstrated a rise in CF antibody titer. One of the two foals demonstrated a rise in VN antibody only. The results suggest that EHV-2 virus induced chronic pharyngitis, primarily the result of lymphoid proliferation, with no overt clinical signs.

Animals↗
PubMedDate not supplied

On the decrease in the life expentancy of black males in Michigan.

The 1970 census reported that there were slightly more than 1 million nonwhites among Michigan's 8,875,000 residents. Ninety-five percent of these nonwhites are black, and 75 percent live within the city limits of Detroit, compared with 10 percent of the State's white residents. Between 1959-61 and 1969-71, life expectancy at birth increased about 1 year for black and white females, essentially remained unchanged for white males, and decreased more than 3 years for black males. In 1969-71, life expectancy was 61 years for black males, 68 years for white males, 69 years for black females, and 75 years for white females. Much of this growing disparity noted resulted from a dramatic rise in deaths of black males in the 15-44 year age group. Two-thirds of this increase was caused by a major rise in mortality from two causes--accidents and homicides. While death rates for black males decreased for a number of other leading causes, these generally remained higher than similar figures for each of the other three race-sex groups. Given current rates, one of eight black males in Michigan ultimately will die from an accident or from homicide. This probability is 1 of 17 for white males, 1 of 30 for white females, and 1 of 26 for nonwhite females. Homicides reduced the life expectancy of black males by 2.3 years, compared with 0.2 year for white males, less than 0.005 year for white females, and 0.5 year for black females. More than three-quarters of all homicides of black males in Michigan in 1973 were caused by handguns.

Accidents↗