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Biomedical subjects

D W Jones

Publications and source records attributed to D W Jones.

At least 127 records · Page 7Linked to original sources
PubMed1991

Treatment of essential hypertension in Asians: enalapril as monotherapy versus combination therapy with hydrochlorothiazide.

This study compared enalapril maleate (Enaprin) as a single antihypertensive agent and enalapril plus hydrochlorothiazide in Korean patients to determine if one regimen is superior to the other in terms of efficacy and subjective adverse effects. After a 1-week washout period, 12 patients were randomized to receive enalapril 10 mg daily and 13 patients to receive enalapril 10 mg daily plus hydrochlorothiazide 25 mg daily. After 2 weeks, enalapril was increased to 20 mg daily if diastolic blood pressure was greater than 90 mm Hg. The study period was 12 weeks. The mean changes in diastolic blood pressure in mm Hg were enalapril alone -10.7 +/- 10.5 mm Hg and enalapril plus hydrochlorothiazide -25.1 +/- 12.1 mm Hg (difference between the two groups significant at p less than 0.01). Mean dose of enalapril required to achieve goal blood pressure was 18.8 mg for monotherapy and 13.0 mg for combination therapy (p less than 0.05). Adverse effects were comparable. We concluded that enalapril in combination with hydrochlorothiazide is more effective and safe, and allows for lower dosing of enalapril than the drug as monotherapy in Korean hypertensives.

Adult↗
PubMed1991

The effect of amphetamine on regional cerebral blood flow during cognitive activation in schizophrenia.

To explore the role of monoamines on cerebral function during specific prefrontal cognitive activation, we conducted a double-blind placebo-controlled crossover study of the effects of 0.25 mg/kg oral dextroamphetamine on regional cerebral blood flow (rCBF) as determined by 133Xe dynamic single-photon emission-computed tomography (SPECT) during performance of the Wisconsin Card Sorting Test (WCST) and a sensorimotor control task. Ten patients with chronic schizophrenia who had been stabilized for at least 6 weeks on 0.4 mg/kg haloperidol participated. Amphetamine produced a modest, nonsignificant, task-independent, global reduction in rCBF. However, the effect of amphetamine on task-dependent activation of rCBF (i.e., WCST minus control task) was striking. Whereas on placebo no significant activation of rCBF was seen during the WCST compared with the control task, on amphetamine significant activation of the left dorsolateral prefrontal cortex (DLPFC) occurred (p = 0.0006). Both the mean number of correct responses and the mean conceptual level increased (p less than 0.05) with amphetamine relative to placebo. In addition, with amphetamine, but not with placebo, a significant correlation (p = -0.71; p less than 0.05) emerged between activation of DLPFC rCBF and performance of the WCST task. These findings are consistent with animal models in which mesocortical catecholaminergic activity modulates and enhances the signal-to-noise ratio of evoked cortical activity.

Adult↗
PubMed1990

Clinical and laboratory features of a severe form of von Willebrand disease in Shetland sheepdogs.

Ten clinically affected Shetland Sheepdogs were evaluated to define their severe bleeding diathesis and were determined to have von Willebrand factor antigen (vWF:Ag) values less than 0.1% by ELISA assay. The virtual absence of vWF protein by ELISA assay and on multimeric analysis was diagnostic of either homozygosity or probable double heterozygosity for the canine von Willebrand disease (vWD) gene. Clinically affected dogs have type-III vWD and are the offspring of 2 heterozygous parents carrying type-I vWD. Twenty-three percent (1,428 dogs) of the more than 6,000 Shetland Sheepdogs screened for vWD at our facility since 1982 tested within the heterozygous carrier range for the common type-I form of this inherited disorder. Veterinarians and breeders should be aware of the potential for bleeding associated with elective and medical procedures in Shetland Sheepdogs and should use caution when breeding carriers of vWD because of the risk of producing clinically affected offspring with severe type-III vWD.

Animals↗
PubMed1990

Clinical compliance of two resilient denture liners.

Although intra-oral-setting resilient denture liners have been used for 30 years to treat the severely resorbed residual ridges of elderly patients, their clinical physical properties are not well understood. The effect of clinical usage on the compliance (compressibility, flexibility) of two intra-oral-setting resilient denture liners was measured in 10 patients, for up to 30 days. The clinical compliance of Material B (Coe-Comfort) was found to be significantly greater than Material A (Veltec) for up to 14 days. At 24 h both materials had significant compliance reductions from the original 1 h measurement. These compliance reductions continued throughout the testing period. For up to 14 days of clinical usage there were no significant differences between the compliance reductions of the two materials. The study suggests that (i) Material B would provide more effective tissue conditioning of abused residual ridge mucosa than Material A; and (ii) a functional impression made with these materials should be left in the mouth for at least 24 h before the cast is poured.

Acrylic Resins↗
PubMed1990

Characterization of Tritrichomonas foetus antigens by use of monoclonal antibodies.

The specificity for and function of monoclonal antibodies against Tritrichomonas foetus were characterized. Four monoclonal antibodies generated by immunization of mice with live T. foetus were selected on the basis of enzyme-linked immunosorbent assay reactions. The approximate molecular masses of the predominant proteins were determined by Western blotting (immunoblotting). Monoclonal antibody TF3.8 recognized a predominant band at approximately 155 kilodaltons, whereas TF3.2 reacted with several bands. Monoclonal antibodies TF1.17 and TF1.15 recognized broad bands between 45 and 75 kilodaltons. The first two antibodies (TF3.8 and TF3.2) did not react with the surface of T. foetus, as determined by live-cell immunofluorescence, agglutination, and immobilization, whereas two other monoclonal antibodies (TF1.17 and TF1.15) did react with surface epitopes, as determined by these criteria. The latter two monoclonal antibodies also mediated complement-dependent killing of T. foetus and prevented of adherence of organisms to bovine vaginal epithelial cells. One antibody, TF1.15, also killed in the absence of complement. Since these functions are in vitro correlates of protection, the antigens recognized by these monoclonal antibodies may induce protective immunity.

Animals↗
PubMed1990

Shapes of benz[a]anthracenes: the crystal and molecular structure of 6-methylbenz[a]anthracene.

The crystal structure of 6-methylbenz[a]anthracene (6-MBA), a more potent carcinogen than the other K-region monomethyl-substituted benz[a]anthracene (5-MBA), has been determined by application of direct methods to single-crystal X-ray diffractometric data and refined by least squares to R = 0.047 (Rw = 0.053). Deviations of the carbon atoms from planarity are very small with even the methyl carbon displaced by only 0.05 A from the mean molecular plane. The benzo-ring A is inclined at only about 1 1/2 degrees to each of the three rings in the anthracene moiety, i.e. 6-MBA is one of the most nearly planar benz[a]anthracenes. The K-region bond C(5)-C(6) = 1.328(6) A and two other short bonds are C(8)-C(9) = 1.341(7) and C(10)-C(11) = 1.361(7) A in the anthracene D ring.

Benz(a)Anthracenes↗
PubMed1989

Clinical implications of resilient denture lining material research. Part I: Flexibility and elasticity.

The clinical use of resilient denture liners is based on their flexibility and elasticity. The nine commercial resilient denture liners measured were less flexible during and after simulated chewing and clenching test sequences. The elasticity of the intraoral-cure liners reached maximal values at 24 hours. Although interpretations require caution, the results imply that the dentist should (1) use maximum liner thickness in the denture base when conditioning abused supporting tissues because of the material's tendency to stiffen under function, and (2) leave a functional impression in the mouth for at least 24 hours before pouring the cast.

Chemical Phenomena↗
PubMed1989

Steric strain and tumorigenicity: the molecular structure of 3,6-dimethylcholanthrene.

The crystal structure of 3,6-dimethylcholanthrene, a highly tumorogenic polycyclic aromatic hydrocarbon, has been solved and refined, from X-ray diffractometric data collected at room temperature, to an R index 0.050 over 1684 independent reflections. The steric strain arising from the presence of the bay-methyl substituent distorts the molecule almost as much as in the moderately carcinogenic 1- and 12-methylbenz[a]anthracenes, with the benzo A ring inclined at approximately 16 degrees to the furthest C and D rings. The 6-methyl carbon atom is displaced 0.7 A from the molecular plane and the beach bond length of the bay region is 1.480(6) A, with beach C-C-C angles of 124.1 and 123.5 degrees. The shortest carbon-carbon bond is C(5)-C(6) = 1.331(7) A at the K region, with the next shortest C(8)-C(9) = 1.362(7), C(10)-C(11) = 1.366(7), and C(3)-C(4) = 1.369(8) A.

Carcinogens↗
PubMed1989

Adherence of Tritrichomonas foetus to bovine vaginal epithelial cells.

Adherence of Tritrichomonas foetus to bovine vaginal epithelial cells (VECs) in vitro was investigated with fresh washed bovine VECs and log-phase cultures of T. foetus. Observation under phase-contrast microscopy showed that T. foetus usually adhered first by the posterior flagellum and later by the body. Significantly more keratinized squamous epithelial cells were detected with attached parasites than nonkeratinized round epithelial cells. The optimal pH range for attachment was 6.0 to 7.5, with peak attachment at pH 6.5 for squamous VECs. Surface-reactive bovine antiserum to T. foetus prevented adherence to bovine squamous VECs. Inhibition of adherence occurred at nonagglutinating, nonimmobilizing serum dilutions. Antiserum fractions enriched for immunoglobulin G1 inhibited adherence, but fractions enriched for immunoglobulin G2 did not. The inhibitory antiserum was specific for several medium- to high-molecular-weight membrane antigens as detected in Western blots (immunoblots). The ability of surface-reactive antibodies to prevent adherence and to agglutinate and immobilize T. foetus indicates that they may be protective.

Animals↗
PubMed1989

Correlation of dental amalgam crevice corrosion with clinical ratings.

In vitro corrosion behavior of gamma 2-containing and gamma 2-free dental amalgams was examined under crevice conditions which simulated the amalgam-tooth interface. By means of potentiostatic testing, current-density/time behavior and integrated anodic current were measured for 16 hr. All of the amalgams demonstrated crevice corrosion susceptibility. Crevice corrosion propagation for gamma 2-free vs. gamma 2-containing amalgams was characterized by lower acceleration and maximum rates during the most dynamic period. Integrated anodic current results were correlated with marginal breakdown ratings reported in two clinical investigations. Strong and significant coefficients were found between integrated current and marginal breakdown ratings when gamma 2-containing and gamma 2-free amalgams were correlated as a single group, but not when correlated separately.

Corrosion↗
PubMed1988

Coatings of ceramics on metals.

An improved understanding of the complexity of the chemical bond theory as it applies to multiphase alloys is developing. A better understanding of compatibility of alloy and ceramic during refiring schedules based upon leucite phase transformations and the ramifications for porcelain failure is emerging. It may also be possible to use other high-expansion glass-ceramic compositions for coating metals. The limitations of bond test methods have been identified. Future bond test methods should aim to make use of fracture toughness theory. Ideally, it should be possible to specify ceramic-to-metal interfacial fracture toughness as a percentage of the fracture toughness of the ceramic interface material. Wet chemical methods have the potential to produce a number of innovative advances in new ceramic and glass biomaterials. These systems may provide a useful method for initial ceramic precoats on metals.

Adhesiveness↗