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Biomedical subjects

J Harp

Publications and source records attributed to J Harp.

10 recordsLinked to original sources
PubMed2001

Weight change among self-reported dieters and non-dieters in white and African American men and women.

Few studies have examined the association between dieting and weight change in general population and results have been inconsistent. To the best of our knowledge, no such study has been done in middle-aged African Americans. We examined 10,554 white and African American men and women who were participants in the Atherosclerosis Risk in Communities (ARIC) Study and attended examinations between 1986 and 1994. We found that the prevalence of dieting in white women, white men, African American women, and African American men was 6.5, 2.3, 3.5, and 0.9%, respectively. After controlling for the covariates, the difference in the mean annual weight gain between dieters and nondieters was 0.61, 0.46, and 0.59 kg/year among white women, white men, and African American women, respectively. In conclusion, in this cohort of white men and women and African American women aged 45-64 years, self-reported dieting was associated with a larger mean annual weight gain than non-dieting over a period of 6 years.

Black or African American↗
PubMed1990

Preliminary studies of mineralization during distraction osteogenesis.

Distraction osteogenesis by the Ilizarov method was performed on 20 dogs. Mineralization at the site of the left tibial metaphyseal lengthening was measured by weekly quantitative computer tomography (QCT) using the contralateral tibia as a control. Four dogs each were killed on Days 7, 14, 21, and 28 of distraction in order to correlate QCT with microradiology, nondecalcified histology, quantitative calcium analysis, and scanning electron microscopy. It was consistently found that intramembranous ossification proceeded centripetally from each corticotomy surface toward the central fibrous interzone. Bone columns crystallized along longitudinally oriented collagen bundles, expanding circumferentially to surrounding bundles. As the distraction gap increased, the bone columns increased in length and in diameter, while the fibrous interzone remained about 4 mm long. Histologically, the bone columns resembled stalagmites and stalactites, as seen by microradiography and scanning electron microscopy, that projected from each corticotomy surface toward the center. These cones reached maximum diameters of 150-200 mu at the corticotomy surfaces. Radiodensity (QCT) increased gradually from the central fibrous interzone toward each corticotomy surface. Mineral density, as determined by calcium quantification, reflected the microscopic geometry and radiographic polarity.

Animals↗
PubMed1989

Randomized, controlled trial of clonidine for smoking cessation in a primary care setting.

Clonidine hydrochloride has been reported to reduce tobacco withdrawal symptoms and facilitate smoking cessation. We enrolled 185 subjects, 92 receiving clonidine and 93 receiving placebo, in a randomized, double-blind study of clonidine for smoking cessation in a primary care setting. Clonidine had no demonstrable effect on withdrawal (8 of 11 measures favoring placebo). At 4 weeks, 17 (18%) subjects receiving clonidine had quit compared with 13 (14%) receiving placebo (chi 2 = 0.7; 90% confidence interval of benefit from clonidine, -4% to 13%). At 4 weeks, the mean number of cigarettes smoked was 17.7 for those receiving clonidine and 17.5 for those receiving placebo (t = 0.1; 90% confidence interval of benefit from clonidine, -4.1 to 3.7 cigarettes per day). These results provide little support for a beneficial effect of clonidine on tobacco withdrawal symptoms, quitting, or smoking reduction in a primary care setting.

Adolescent↗
PubMed1986

Subfractionation of soluble macronuclear chromatin and enrichment of specific genes as chromatin from Euplotes eurystomus.

Euplotes eurystomus is a hypotrichous ciliated protozoan possessing within one cytoplasm a transcriptionally-inactive micronucleus with chromosomal-size DNA and a transcriptionally active macronucleus with "gene-size" DNA fragments. The chromatin in the macronucleus can be isolated in a soluble form without prior treatment by nucleases. In this study, macronuclear, soluble chromatin was subfractionated using isokinetic sucrose density gradient ultracentrifugation in a buffer consisting of 50 mM NaCl, 1 mM Na2 EDTA, 1 mM TEA HCl, pH 7.0, 0.1 mM TLCK and 0.1 mM PMSF. Fractions were collected and analyzed by DNA and protein gel electrophoresis, dot blot hybridization with specific gene probes, and modified Miller chromatin spreads. Analysis of the chromatin spreads showed that the sizes of the chromatin fragments in the various fractions correlate with the DNA size of the fragments. When dot blots of the fractions were hybridized with 5S rRNA, tubulin and rRNA gene probes we obtained about a 6 to 14-fold enrichment of hybridizable sequences in individual fractions. There appear to be differences in the non-histones present on each fraction as well as some overall similarities in histone and non-histone proteins.

Animals↗
PubMed1986

Preparation and characterization of soluble macronuclear chromatin from the hypotrich Euplotes eurystomus.

Euplotes eurystomus is a hypotrichous ciliate containing a transcriptionally active macronucleus (MAC) and a transcriptionally inactive micronucleus. Soluble MAC chromatin contains a normal complement of inner histones, an H1-like protein which is very sensitive to proteolysis, and a considerable proportion of non-histone proteins. A combination of N-Tosyl lysine chloromethyl ketone (TLCK) and PMSF was found to be most effective in preventing proteolysis. Microccocal nuclease digestion yielded an average nucleosome repeat length of 187 +/- 25 bp for soluble chromatin; and 190 +/- 9 bp for isolated macronuclei. Thermal denaturation profiles of MAC chromatin in 0.25 mM EDTA display two main transitions at about 76 and 83 degrees C, resembling the melting of soluble chicken erythrocyte chromatin. Circular dichroic spectra of MAC chromatin were compared to soluble chicken erythrocyte chromatin under the same ionic strength conditions and were found to be very similar. 2D chromatin/DNA agarose gel electrophoresis resulted in a diagonal line of DNA staining, which establishes a strict correlation between DNA and chromatin electrophoretic mobility.

Animals↗