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Biomedical subjects

D W Chandler

Publications and source records attributed to D W Chandler.

25 records · Page 2Linked to original sources
PubMed1981

The interaction of RNA polymerase II with non-promoter DNA sites.

Various complexes formed between purified RNA polymerase II and simian virus 40 DNA have been characterized with respect to rates of formation, rates of dissociation, and initial velocity of RNA synthesis. Two different types of complexes can form on intact DNA templates. One of these is formed rapidly, but is quite labile; the other forms more slowly, but is moderately stable once formed. The introduction of a single strand break into DNA leads to rapid and stable complex formation, and thus is expected to create the favored binding site. The observed properties of these complexes provide a general framework for describing the interactions of RNA polymerase II at non-promoter DNA sites. This framework appears to be similar to that established for Escherichia coli RNA polymerase interactions, suggesting that the fundamental mode of non-promoter DNA binding is similar for the bacterial, plant, and mammalian enzymes.

Animals↗
PubMed1976

The measurement of 18-hyroxy-11-deoxycorticosterone in human plasma by radioimmunoassay.

A radioimmunoassay method for the measurement of plasma levels of 18-hydroxy-11 -deoxycorticosterone (18 -OH-DOC) has been developed. The antiserum against 18-OH-DOC was produced in rabbits immunized against 18-OH-DOC-3-oxime-bovine serum albumin. Plasma (1-2 ml) was extracted with dichloromethane and chromatographed on paper. The purified extracts were incubated with antiserum at a 1/22,000 dilution for 1/2 hour at 37 degrees C and for 2 hours at 4 degrees C. Saturated ammonium sulfate was used to separate free from bound 18-OH-DOC. 1,2-3H-18-OH-DOC was added to all samples to correct for losses and to determine the percent free. Pyridine (0.1%) was added to solvents to maintain the stability of 18-OH-DOC. Recovery after extraction was 58 +- 8 (S.D)%. The accuracy and precision of the method were acceptable, and a sensitivity of 2 pg per sample enabled the measurement of very low levels of 18-OH-DOC. High specificity was demonstrated by a low blank value (0 +- 0.2 pg) and by demonstrating that alternative paper chromatography separation systems gave results not differing significantly from those obtained by the present method. The mean 8AM plasma 18-OH-DOC level was 8.5 +- 1.2 ng per 100 ml in18 normotensive control subjects. There was a marked response of plasma 18-OH-DOC to ACTH stimulation and dexamethasone suppression and a significant increase after 3 hours upright posture.

18-Hydroxydesoxycorticosterone↗
PubMed1975

Cyclic AMP content of gingival fluid in women taking oral contraceptives.

Gingival fluid samples were collected from 12 healthy adult women who ranged in age from 19 to 34 years. Seven subjects with normal menstrual cycles who received no medications acted as controls while five subjects who had been using oral contraceptives for a minimum of 17 months constituted the experimental group. The women using birth control pills showed a 53% increase in the gingival fluid volume versus the controls. Radioimmunoassay revealed a mean concentration of cyclic adenosine monophosphate (cAMP) in the gingival fluid of 3.8-10(-6)M in the controls and 1.9-10(-6)M in subjects using oral contraceptives, although the total amount of cAMP present in the fluid from both groups was equal. These gingival fluid cAMP levels were a hundredfold higher than those measured in serum and saliva.

Adult↗
PubMed1975

Differences in cAMP levels in the gingival fluid of diabetics and nondiabetics.

Gingival fluid from eight control subjects and ten diabetics was collected and the content of cAMP and protein in the fluid was assayed to determine the nature of the biochemical changes occurring in the gingival fluid due to diabetes. The gingival fluid of the control subjects had a cAMP concentration of 2.4 X 10(-6) M, which was a hundredfold greater than that seen in serum, thus suggesting that the cAMP in the fluid resulted from active synthesis by the gingival cells and was not merely a transudate from the blood. The gingival fluid of the diabetics contained only one-seventh the level of cAMP seen in the control group. It is suggested that the decreased level of cAMP seen in the givgival fluid of diabetics may be a manifestation of a defect in the cAMP forming mechanism of the gingival tissue, which may reflect the systemic etiology of diabetes. It was also found that in the control subjects the content of cAMP in the gingival fluid was in inverse proportion to the volume of exudate in the gingival crevice. No such relationship was seen in the diabetic group. It appears that the level of cAMP present in the gingival fluid of normal individuals without any generalized endocrine deficiencies may be used as an additional indicator of the inflammatory status of the gingival tissues, along with the clinical evaluation based on gingival index.

Adult↗