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Biomedical subjects

B L Jackson

Publications and source records attributed to B L Jackson.

6 recordsLinked to original sources
PubMed1988

Human platelet thermostable phenol sulfotransferase from blacks and whites: biochemical properties and variations in thermal stability.

Phenol sulfotransferase (PST) catalyzes the sulfate conjugation of catecholamines and of phenolic drugs. Human platelet PST exists in at least a thermolabile form (TL PST) and a thermostable form (TS PST). The mean basal level of platelet TS PST activity in samples from American blacks is significantly higher than the basal activity in samples from whites. We carried out the studies reported here to determine whether the higher basal TS PST activity in platelet homogenates from blacks was biochemically similar to the lower basal activity in samples from whites. We also characterized variations in TS PST thermal stability. Platelet TS PST activities in samples from the two groups were almost identical with respect to pH optima, Michaelis-Menten constant values for substrates, and susceptibilities to inhibition by 2,6-dichloro-4-nitrophenol and sodium chloride. Thermolabile and thermostable TS PST were present in samples from both blacks and whites. Thermal stabilities of TS PST in samples from 167 volunteers (104 blacks, 63 whites) were expressed as heated sample-to-control sample ratios. Bimodal frequency distribution histograms of the heated-to-control ratios revealed subgroups of samples with thermolabile TS PST activities from 13.5% of blacks (heated-to-control ratio less than 0.32) and 12.7% of whites (heated-to-control ratio less than 0.27). The mean heated-to-control ratio for thermostable TS PST from blacks was significantly higher than that from whites (0.52 +/- 0.01 vs 0.43 +/- 0.01, respectively, mean +/- SEM; p less than 0.0001). Our studies demonstrated the similarity of biochemical properties of platelet TS PST at the extremes of basal activity. They also showed equivalent subgroups of blacks and whites with thermolabile TS PST. The results are an important initial step toward testing the hypothesis that inheritance may be one factor in the regulation of basal levels of activities and thermal stabilities of platelet TS PST from American blacks.

Adult↗
PubMed1987

Inter- and intra-examiner reliability of the upper cervical X-ray marking system: a second look.

To determine the degree of reliability (stability over time) for six Pettibon practitioners, the scores resulting from the reading and re-reading of 30 X rays were analyzed using bivariate scattergrams, Pearson Product-moment correlation coefficient estimates and correlated samples t tests. To examine reliability (equivalence over experts) across the practitioners, a repeated measures analysis of variance approach was used. Liberal and conservative reliability coefficients for the upper angle and lower angle were computed. Examination of the data suggest that the reliability (stability over time) for the practitioners is very good. The data on reliability (equivalence over experts) across the practitioners also suggests reliability is very good.

Cervical Vertebrae↗
PubMed1986

Human pituitary phenol sulfotransferase: biochemical properties and activities of the thermostable and thermolabile forms.

Pituitary tissue contains phenol sulfotransferase (PST), the enzyme that catalyzes the sulfate conjugation of monoamine neurotransmitters. We carried out these studies with pituitaries obtained 21.3 +/- 3.0 h postmortem (mean +/- SEM; n = 21) to determine whether the biochemical properties and variations in levels of human pituitary PST activities were similar to those of PST in platelets from control subjects. PST in the human platelet has been studied thoroughly because of the possibility that platelet PST might reflect levels of PST activity in other tissues such as the pituitary and brain. Our results demonstrated 2 forms of the pituitary enzyme that were similar to the thermostable (TS) and thermolabile (TL) forms of platelet PST with regard to assay conditions, pH optima, Km values for multiple substrates, responses to 2,6-dichloro-4-nitrophenol (DCNP), and thermal stability properties. Pituitary samples also were obtained at autopsy 6.3 +/- 0.33 h (mean +/- SEM; n = 3) after death to determine the effects of storage at 4 degrees C on PST activities. After storage for 6-18 h, 83-99.6% of the TS PST activity remained and 44-66.9% of the TL PST activity remained. Pituitary TS PST activity in samples obtained within 12.1 +/- 3.25 h after death was 121.0 +/- 49.1 units/mg protein (mean +/- SEM; n = 7) with a range from 9.7 to 367.6. TL PST activity was 35.6 +/- 11.6 units/mg protein (mean +/- SEM; n = 6) with a range from 6.1 to 80.7. Wide variations of both enzyme activities were also present in 3 pituitary tumor samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1978

Comparative effect of calcium and of the adrenergic system on calcitonin secretion in man.

This study evaluated the effects of adrenergic agents on immunoreactive calcitonin (iCT) secretion in normal man, and compared the time course and magnitude of these adrenergic effects with those caused by modifying calcium (Ca) ion concentration. Ca infusion (15 mg Ca++/kg iv in 4 h) significantly increased plasma iCT within 1 h, reaching 140 +/- 8% of baseline at 4 h. EDTA (50 mg/kg iv in 2 h) significantly decreased plasma iCT within 15 min, with nadir value of 53 +/- 4.9% of baseline at 2 h. The beta-adrenergic agonist, isoproterenol, significantly increased plasma iCT with 5 min, reaching 136 +/- 5.9% of baseline at 30 min. The alpha-adrenergic antagonist, phentolamine, significantly increased iCT within 15 min, reaching 132 +/- 8.6% of baseline at 45 min. The beta-adrenergic antagonist, propranolol, significantly suppressed iCT with 15 min, reaching 51.8 +/-6.3% of baseline at 2 h. Therefore, 1) the adrenergic system (without induced change in serum Ca) can modify CT secretion to as great a degree as can change in Ca ion concentration induced by standard Ca and EDTA infusion tests and 2) even basal secretion of CT can be modified by adrenergic influences. These data strongly suggest 1) that the adrenergic system is an effective modifier of CT secretion and 2) that the adrenergic system, as well as Ca ion concentration, may play an improtant physiological role in control of CT secretion in man.

Adult↗