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Biomedical subjects

D E Jones

Publications and source records attributed to D E Jones.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Hearing loss in patients with diabetic retinopathy.

With use of standard audiometric procedures, the hearing thresholds of patients with known diabetic retinopathy did not differ significantly from those of a control population group. However, use of a more subtle psychoacoustic tool--a filtered speech task--showed a definite difference in hearing acuity between the two groups.

Adult↗
PubMedDate not supplied

Comparison of catheterization and Doppler-derived pressure gradients in a canine model of subaortic stenosis.

The relationship between Doppler-estimated and catheterization-measured pressure gradients was examined by repeated-measures linear regression analysis and difference plots in 15 dogs with naturally occurring subvalvular aortic stenosis. Thirty left ventricular outflow tract gradients were compared during sinus rhythm and 142 gradients during premature or postextrasystolic beats for the following pairs of data: (1) mean catheterization gradient versus mean Doppler gradient, (2) maximal instantaneous catheterization gradient versus maximal Doppler gradient, and (3) peak-to-peak catheterization gradient versus maximal Doppler gradient. The correlation between Doppler-derived and catheterization-derived pressure gradients was excellent (r = 0.99; p < 0.001) for the maximal instantaneous (sinus rhythm: standard error of the estimate [SEE] = 5.7 mm Hg; premature and postextrasystolic beats: SEE = 6.7 mm Hg) and mean gradients (sinus rhythm: SEE = 3.6 mm Hg; premature and postextrasystolic beats: SEE = 4.5 mm Hg). There was also a strong correlation between the peak-to-peak catheterization gradient and the maximal Doppler gradient (sinus rhythm: r = 0.99, p < 0.001, SEE = 5.3 mm Hg; premature and postextrasystolic beats: r = 0.97, p < 0.001, SEE = 7.2 mm Hg). Agreement between the two techniques was best for mean gradients and most disparate for the comparisons of maximal Doppler gradients and peak-to-peak catheterization gradients.

Animals↗
PubMedDate not supplied

Environmental exposures that affect the endocrine system: public health implications.

In recent years much attention has been focused on the potential for a wide range of xenobiotic chemicals to interact with and disrupt the endocrine systems of animal and human populations. An overview of the chemicals that have been implicated as endocrine disruptors is presented. The ubiquity in the environment and associated body burdens of these chemicals in human populations are described. Potential mechanisms of action are reviewed, including the role of specific intracellular receptors and their interactions with endogenous and exogenous materials. The subsequent upregulation or downregulation of physiological processes at critical stages of development is discussed. The potential for joint toxic action and interaction of chemical mixtures is also discussed. The acknowledged role of wildlife populations as sentinels of potential human health effects is reviewed, and the weight of evidence for the role and impact of endocrine disruptors is presented. The implications of exposure to endocrine-disrupting chemicals for human health are reviewed, with special emphasis on the potential for transgenerational effects in at-risk populations. Recommendations for future research include the development of (1) structural activity and in vivo and in vitro functional toxicology methods to screen chemicals for their endocrine-disrupting ability, (2) biomarkers of exposure and effect, and (3) in situ sentinel systems.

Animals↗
PubMedDate not supplied

A preliminary study of joint surface changes after an intraarticular fracture: a sheep model of a tibia fracture with weight bearing after internal fixation.

OBJECTIVE: To evaluate the changes in the articular cartilage and subchondral bone after an osteotomy designed to simulate an articular fracture. DESIGN: The contribution of the cartilage and subchondral bone was evaluated twelve weeks after creating a 1.0-millimeter step-off in the medial plateau of the tibia of twelve adult domestic sheep. All animals surviving were labeled with fluorescent markers for bone production, oxytetracycline (fifty milligrams per kilogram), and calcein (twelve milligrams per kilogram) nine and 11.5 weeks after surgery. The knees were loaded in compression using an Instron materials tester with pressure-sensitive film to record joint contact pressures above and below the medial meniscus. SETTING: The studies were performed in the research laboratories of the Orthopaedic Laboratory at Harborview Medical Center in Seattle, Washington and the Madigan Army Medical Center in Tacoma, Washington. ANIMALS: Twelve adult domestic sheep. INTERVENTION: An intraarticular osteotomy of the medial tibial plateau with 1.0 millimeter of displacement was performed. The osteotomy was stabilized with 3.5-millimeter lag screws. MAIN OUTCOME MEASURES: The contact pressures of the knee joint and articular histology were evaluated twelve weeks after surgery. Samples of the articular cartilage were analyzed by light microscopy and electron microscopy to evaluate the response of the articular cartilage and subchondral bone of the differential joint loading because of the irregularity in the articular surface caused by the osteotomy. RESULTS: The knees with an intraarticular step-off had two major contact areas with an intervening zone of reduced load corresponding to the edge of the depressed fragment. Coronal histologic sections through the articular surface showed the presence of thinning and fibrillation on the high side of the step-off and some compensatory hypertrophy of the cartilage. The subchondral bone was not responsible for restoring articular congruity because the rate of bone production was similar between the low side of the articular fracture (1.85 micrometers per day) and the high side of the fracture (1.67 micrometers per day). Scanning electron microscopy showed partial cartilage remodeling by deformation of the high side cartilage with bending of the vertical collagen fibrils, even in the unloaded state. CONCLUSIONS: In this model with a small fracture displacement (1.0 millimeter), which was less than the thickness of the articular cartilage (1.5 millimeters), the contour of the joint improved despite residual articular surface incongruency after the fracture healing.

Animals↗
PubMedDate not supplied

Postcoital test: which form of spermatozoal motility is associated with a good fertility outcome?

The objectives of this study were to examine the predictive value of the PCT in relation to treatment-independent conception rates, to determine which cutoff point best predicted fertility outcome, and which form of spermatozoal motility on PCT is most significantly related to fertility outcome. A prospective study was undertaken of couples referred for the investigation of "unexplained" infertility. One hundred and twenty six couples were recruited between July 1984 and April 1986. On further investigation female infertility factors were identified in 32 (25%) of couples, who were therefore excluded from the study. All conceptions were treatment independent. The relationship between the result of the postcoital test and the chance of conception was studied using a modification of Cox's regression model of life table analysis. The mean length of involuntary infertility prior to referral was 75 months (range = 18-192, SD = 39.2). The mean length of follow-up was 18 months (range = 1-34, SD = 8.4). A 98% follow-up rate was achieved. Eighteen women conceived, giving a 32-month treatment-independent conception rate of 22%. A cutoff point of one spermatozoon exhibiting sluggish motility per HPF was the most effective method of classifying the results of the postcoital test (X2(1) = 4.28, P = 0.037, RR = 4.7. This would suggest that the most efficient form of spermatozoal motion in cervical mucus is slow or sluggish motility.

Adult↗