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Biomedical subjects

D H Bell

Publications and source records attributed to D H Bell.

At least 19 recordsLinked to original sources
PubMed1991

Gestational diabetes mellitus among African-American women.

Gestational diabetes mellitus (GDM) is associated with increased risk of poor outcomes for the pregnancy. It is a strong risk factor for subsequent diabetes. The epidemiology of GDM in African-American women is not well known. It has not been demonstrated that their risk factors are similar in character and weight to those among White women. There is considerable multicollinearity among GDM risk factors such as age, parity, obesity, hypertension, and family history of diabetes, and this needs to be sorted out. This review is based on the results of a nested case-control study to evaluate the frequency of, and the relationships of the known risk factors with, the onset of GDM among African-American women. All cases of GDM within a cohort of women seen at any of the county health department clinics in Jefferson County, Alabama from 1981 to 1987 were identified. The cohort represents approximately 63% of all African-American pregnancies in the county during the period. With few exceptions (5.1% based on fasting plasma glucose greater than or equal to 120 mg/dl), potential GDM cases (7.1%) were selected on the basis of a 2 h post 100 g carbohydrate meal screening plasma glucose measure at their second prenatal visit and again at 28-32 weeks greater than or equal to 115 mg/dl and diagnosed on the basis of the results of an oral glucose tolerance test (OGTT) using the criteria of O'Sullivan and Mahan. Women with any prior history of diabetes (even in pregnancy), 1.6%, were excluded. The frequency of the new diagnosis of GDM among African-American women in this pregnancy in the cohort was 2.5% of pregnancies and 3.4% of women, which is similar to the values reported in the other studies. Controls were selected from women with negative screening tests who delivered after a GDM subject. The results reported in this paper reflect 358 cases (86% of all eligible GDM cases identified) and 273 controls. Cases were significantly older (28.3 vs. 21.7 years), of higher gravidity (2.7 vs. 1.9), more obese (76.7 vs. 61.7 kg), gained weight more rapidly (0.34 vs. 0.28 kg/week), had more hypertension in this pregnancy (28.2 vs. 2.6%), and there was a higher proportion with a family history of diabetes (41.3 vs. 16.5%) (p less than 0.001 for all comparisons). Because there were significant correlations among the risk factors in both cases and controls, multivariable logistic regression analyses were performed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Antiinflammatory and antiarthritic properties of a substituted quinoline carboxylic acid: CL 306,293.

CL 306,293, a substituted quinoline carboxylic acid at a daily oral dose between 1.5 and 3.0 mg/kg suppressed the inflammation and joint destruction (radiological criteria) associated with both developing and established adjuvant arthritis. When a weekly oral dosing regimen was used, joint destruction was attenuated when this agent was administered at a dose of 50 to 200 mg/kg. Inflammation associated with a delayed type hypersensitivity reaction in dogs was suppressed at a daily dose of 0.25 mg/kg or a weekly dose of 1 mg/kg. At efficacious doses, CL 306,293 had no effects on cyclooxygenase or lipoxygenase activities nor did it have an effect on carrageenin induced paw edema. In acute tests, the compound was not ulcerogenic. The above observations indicate that the antiinflammatory effects of CL 306,293 are distinct from those observed with nonsteroidal antiinflammatory agents. Mechanistic studies conducted and to be published indicate that CL 306,293 down regulates T cell function and this mechanism may account, at least in part, for the antiinflammatory and antiarthritic properties observed in animal models of inflammation and joint destruction.

Administration, Oral↗
PubMed1988

Characterization of the fluorescence of the antitumor agent, mitoxantrone.

Studies have been conducted on the absorption, fluorescence excitation and fluorescence emission of mitoxantrone, an important antineoplastic agent. Mitoxantrone has been found to fluoresce with excitation maxima at 610 and 660 nm and emission maximum at 685 nm. Further characterizations of the fluorescence were undertaken to study its usefulness in biological studies. Mitoxantrone fluorescence intensity is altered by pH and the emission spectrum is red-shifted by DNA. Furthermore, the fluorescence polarization is enhanced by DNA, confirming the binding of the antitumor agent to DNA. The fluorescence spectra are slightly modified by changes in ionic strength and the addition of albumin. Data establishing the usefulness of fluorescence to measure serum concentrations in the range of 0.0 to 100 nM are presented. Such determinations can distinguish serum mitoxantrone from its non-fluorescent primary metabolite.

Animals↗
PubMed1988

Template for positioning and angulation of intraosseous implants.

Presurgical planning for submerged implant location and angulation within bone relative to the opposing occlusion is important for the prosthodontist. This information is accurately communicated to the surgeon by using a surgical template. A technique for fabrication of the template is described.

Dental Implantation, Endosseous↗
PubMed1987

Effect of low dose methotrexate on neutrophil chemotaxis induced by leukotriene B4 and complement C5a.

When mediators of inflammation such as complement component C5a or leukotriene B4 are introduced into an air pouch created in mice, these mediators induce the migration of neutrophils into the air pouch. Pretreatment of mice with low doses of methotrexate inhibits leukotriene B4 or C5a induced neutrophil migration into the air pouch. Inhibition of neutrophil chemotaxis by methotrexate may, at least in part, account for the rapid onset of antiinflammatory activity that was observed in clinical trials with methotrexate in rheumatoid arthritis.

Animals↗
PubMed1986

Particles versus solid forms of hydroxyapatite as a treatment modality to preserve residual alveolar ridges.

In two separate but related studies, different forms of hydroxyapatite were implanted into the extraction sockets of human teeth to delay alveolar resorption and to form the background for a comparison of the treatment modalities. The significant differences in the treatment modalities and the postoperative sequelae seem to merit this report. The implantation of the particles appears to be clinically, a more expedient procedure than the implantation of cones. The time required to select an appropriate-sized cone, modify the cone as needed to achieve a snug fit into the extraction socket, and seat the cone deeply enough in the extraction socket to assure at least 2 mm of bone above the top of the cone implant was significantly greater than the time required to fit and pack particles into an extraction socket. None of the postimplantation problems encountered with cones was encountered in using the particle implants. The postimplantation problems encountered with cones included submucosal prominence, erosion through the mucosa (dehiscence), migration, loss of the implant, or surgical maintenance or resubmergence. Data from these two studies suggest that the implantation of particles into the extraction sockets of human teeth to delay alveolar ridge resorption is a more prudent, forgiving, considerate, problem-free, and predictable procedure than the implantation of cones.

Adult↗
PubMed1984

Epithelial fusion during early semicircular canal formation in the embryonic zebrafish, Brachydanio rerio.

The developing inner ear of the teleost, Brachydanio rerio, provides an opportunity for observing an epithelial fusion between the apical surfaces of apposed epithelia in a vertebrate embryo in vivo. The developing otocyst was filmed for periods up to 4 days in unanesthetized embryos, and specimens were fixed at intervals and processed for light microscopy, TEM, and SEM. The semicircular canals are formed as a consequence of the union between the tips of three cylindrical projections from the wall of the otocyst, which grow toward corresponding bulges of a projection from the lateral wall. The epithelial cells covering the projections contain extensive rough endopasmic reticulum, exhibit apical junctional complexes, and are not underlain by a basal lamina. The core of each projection contains large amounts of flocculent and fibrillar extracellular material. After a period of growth and elongation, the tip of each projection contacts, and adheres to, the appropriate bulge to create a circular, flattened, bilayered, epithelial plate. Small, focal junctions form between the apposed apical cell surfaces within the plate during this period, but they are not numerous. Junctional complexes do develop, however, between apposed cells at the periphery of the plate. After 1-2 hours, the basal surface of the plate exhibit considerable alteration in contour. Adjacent cells within the plate then separate to allow continuity of the connective tissue components of the two structures. The observations of this study indicate that following an initial period of contact and adhesion, cellular reorientation and changes in junctional contacts between adjacent cells within the epithelial plate, rather than cell degeneration, are responsible for perforation of the plate.

Animals↗
PubMed1984

Mitotic neuroblasts in the 9-day-old and 11-month-old rodent hippocampus.

Ultrastructural identification of mitotic neuronal precursors beneath the basal hippocampal granule cell layer was made using electron micrographs of [3H]thymidine-labeled cells. Ultrathin sections were obtained by a method that allows serial thin sectioning of reembedded sections previously prepared for light microscopic radioautography. The electron microscopic observations reported in this study reveal: (1) that a steady rate of granule cell neurogenesis occurs during the first year of a rodent's life; (2) that newly formed granule neurons in the dentate gyrus of the newborn mouse and adult rat are a result of neuroblast division; and (3) two distinct classes of mitotic cells can be identified during the peak period of postnatal neurogenesis--those with synapses on their cell bodies and processes and those with no synapses or processes.

Animals↗
PubMed1983

Neuronal proliferation in the 9-month-old rodent-radioautographic study of granule cells in the hippocampus.

Nine-month-old rats were injected with 5 microCi 3H-thymidine (3H-Tdr) and allowed to survive for 20 days. In light-microscopic radioautographs, labeled cells were found in the granule cell layer of the hippocampus. Analysis of electron micrographs of the labeled cells, taken from re-embedded 1.5 micron radioautographic sections, clearly demonstrated their neuronal nature with synapses along their cell bodies and dendrites. Our results indicate that 0.025% of the granule neurons are heavily labeled in the dorsal hippocampus. Electron microscopy of re-embedded light-microscopic radioautographic sections confirms that granule neurons in the rodent are newly formed up until 9 months after birth.

Aging↗
PubMed1983

Pathology (?) of Plagiorhynchus cylindraceus in the starling, Sturnus vulgaris.

Our field study did not support anecdotal claims alleging pathogenicity on the part of P. cylindraceus in starlings. Within-clutch analysis of nestling starling weights (n = 25) over time showed that P. cylindraceus had no effect on position in clutch relative to siblings. Parasitized nestlings tended to weigh more than control siblings. Within-sex analysis of wild adult starling weight (n = 103) showed no difference between animals with acanthocephalans and uninfected animals and weight was not related to intensity of infection. Host response to the proboscis was limited to immediately-surrounding tissue (90 microns). Other observations made in this study included the following: (1) no evidence for deleterious intraspecific interaction among adult P. cylindraceus in starlings; (2) no apparent interspecific interactions between P. cylindraceus and (unidentified) cestode species in starlings; and (3) copulatory caps on male P. cylindraceus may be a response to environmental deterioration in dead hosts.

Acanthocephala↗