Biomedical subjects
B Childs
Publications and source records attributed to B Childs.
X-linked hypoxanthine-guanine phosphoribosyl transferase deficiency: heterozygote has two clonal populations.
Clones of skin fibroblasts cultured from the mother of two sons with X-linked hypoxanthine-guanine phosphoribosyl transferase deficiency (Lesch-Nyhan syndrome) were assayed for activity of this enzyme by measurement of the incorporation of (3)H-guanine into guanylic acid as counts per minute per microgram of protein and by autoradiography. The demonstration of two populations of clones, wild-type clones with normal enzyme activity and mutant clones unable to incorporate (3)H-guanine, is evidence that the locus for hypoxanthineguanine phosphoribosyl transferase on one of the X chromosomes is inactive.
Glucose 6-phosphate dehydrogenase in Drosophila malanogaster: starch gel electrophoretic variation due to molecular instability.
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Clinical and genetic heterogeneity in idiopathic Addison's disease and hypoparathyroidism.
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Familial nonhemolytic jaundice with late onset of neurological damage.
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Patterns of alkaline phosphatase in developing Drosophila.
Electrophoretic study of alkaline phosphatase in developing Drosophila shows that different stages are characterized by the appearance and disappearance of organ-specific enzyme bands. A new electrophoretic variant, from adult hindgut, is controlled by the second chromosome locus Aph-2.
X-linked 6-phosphogluconate dehydrogenase in drosophila: subunit associations.
6-Phosphogluconate dehydrogenase (PGD) subunits have been dissociated and reassociated in vitro. The intermediate PGD of the heterozygous phenotype is reproduced by reassociation in vitro of subunits derived from the two types of PGD from homozygous flies. This result has a bearingon gene action in the diploid organism and on the mechanism of dosage compensation in Drosophila melanogaster.
The genetics of learning disabilities.
Rapid progress in the study of learning disabilities requires a common context within which investigators and professionals with very diverse backgrounds can work towards common goals. Much evidence points to the heterogeneity of origin and clinical expression of learning disabilities as well as to many other ways in which they resemble such multifactorial conditions as mental retardation, gout and hypertension. In these conditions, genetic and epidemiological methods have been used to sort out the constitutional and environmental factors which precipitate disease in susceptible persons. Such an approach to learning disabilities can be expected to be rewarding.
Prevalence of hypertension in patients with type II diabetes in referral versus primary care clinics.
We compared the prevalence of hypertension in patients with non-insulin-dependent diabetes mellitus (NIDDM) in referral and primary care practices using definitions of The Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC-V), while controlling for other risk factors such as hypertension, obesity, smoking, and age. Patients (n = 1443) were enrolled consecutively from a large referral practice at the Jackson Diabetes Center and four primary care clinics in the vicinity. Blood pressures were measured at three clinic visits after a 5-min rest in a sitting position using a standard clinical sphygmomanometer. Charts were reviewed to determine diabetes duration, insulin usage, height, weight, smoking history, use of antihypertensive and oral hypoglycemic medications, socioeconomic status, and race. Patients were classified as hypertensive based on JNC-V definitions or if they were on antihypertensive medication. Hypertension was termed uncontrolled if blood pressure was JNC-V Stage 2 or higher while on antihypertensive medication. Seventy-eight percent of referral clinic and 55% of primary care clinic patients had either JNC-V State 1 or higher hypertension or were on antihypertensive medication. Actual blood pressures indicated that more patients had JNC-V Stage 1 (mild) or higher hypertension in referral compared to primary care clinics (62% versus 48% p = 0.01) but fewer had JNC-V Stage 2 or higher (moderate-severe) hypertension (12% versus 19% p = 0.002). Patients seen in the referral clinic were significantly more likely to have greater age, greater duration of diabetes, higher insulin dosage, longer smoking history, antihypertensive medication, and live outside the metropolitan area. By logistic regression, the odds of hypertension were significantly increased with age (OR 1.51/decade), BMI greater than 27 (OR 2.17), diabetes duration (OR 1.04/year), and insulin dosage (OR 1.74/U/kg). Current smoking and attending a referral clinic were not significantly related. The odds of moderate-severe hypertension were significantly increased with age (OR 1.23/ decade), decreased by attending a referral clinic (OR 0.45), and not significantly related to other confounders in the model. The prevalence of hypertension among patients with NIDDM was higher in referral than primary care clinics. The higher prevalence in the referral practice can be accounted for by the greater severity of associated risk factors in the referral practice patients; however, most patients will be diagnosed and treated for hypertension prior to referral. More patients in the referral practice were on hypertensive medication, which lowered the stage or severity of hypertension but still not to the normal range. The results suggest that the primary detection of hypertension in patients with type II diabetes resides with the primary care physician. Management of hypertension will require both a delineation and acceptance of responsibilities between the primary care physician and diabetes specialists.
Analytical methods for water disinfection byproducts in foods and beverages.
The determination of exposure to drinking water disinfection byproducts (DBPs) requires an understanding of how drinking water comes into contact with human through multiple pathways. In order to facilitate the investigation of human exposure to DBPs via foods and beverages, analytical method development efforts were initiated for haloacetonitriles, haloketones, chloropicrin, and the haloacetic acids (HAAs) in these matrices. The recoveries of the target analytes were investigated from composite foods and beverages. Individual foods and beverages used to investigate the general applicability of the developed methods were selected for testing based on their watercontent and frequency of consumption. The haloacetonitriles, the haloketones, and chloral hydrate were generally well recovered (70-130%), except for bromochloroacetonitrile (64%) and dibromoacetonitrile (55%), from foods spiked after homogenization and following extraction with methyl-t-butyl ether (MTBE); the addition of acetone was found to be necessary to improve recoveries from beverages. The process of homogenization resulted in decreased recoveries for the more volatile analytes despite the presence of dry ice. The HAAs were generally well recovered (70-130%), except for trichloroacetic acid (58%) and tribromoacetic acid (132%), from foods but low recoveries and emulsion formation were experienced with some beverages. With both groups of analytes, certain matrices were more problematic (as measured by volatility losses, emulsion formation) than others with regard to processing and analyte recovery.