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Biomedical subjects

J C Christian

Publications and source records attributed to J C Christian.

161 records · Page 9Linked to original sources
PubMed1971

Pierre Robin syndrome occurring in two related sibships.

Four children affected with Pierre Robin syndrome occurring in two related sibships are described. The fathers of these sibships are second cousins and both of them have deceased sibs with histories of respiratory or feeding difficulties or both, or cleft palate. Mode of inheritance suggested by these findings is autosomal dominant with variable expression and incomplete penetrance.

Adult↗
PubMed1971

Hypogandotropic hypogonadism with anosmia: the Kallmann syndrome.

Five cases are presented and the literature reviewed concerning the association of anosmia or hyposmia and hypogonadotropic hypogonadism (Kallmann syndrome). Two of the five cases are sporadic and without associated anomalies, the third is associated with ichthyosis and epilepsy, the fourth has a sister with hypogonadism and cleft lip and palate while the fifth case also has Albright's hereditary osteodystrophy (pseudopseudohypoparathyroidism). It is concluded that "Kallmann syndrome" is present in a wide spectrum of disorders with different genetic etiologies.

Adult↗
PubMedDate not supplied

High density lipoprotein cholesterol. A 16-year longitudinal study in aging male twins.

The National Heart, Lung, and Blood Institute Twin Study is a collaborative, longitudinal study of white, male twins who were veterans of World War II and were born between 1917 and 1927. The twins were selected from the National Academy of Sciences/National Research Council Twin Panel and were examined three times (1969-73, 1981-82, and 1986-87). At all three exams, the dizygotic (DZ) twins were found to have a greater total variance for high density lipoprotein cholesterol (HDL-C) than the monozygotic (MZ) twins (p less than 0.05). DZ variance estimates were also larger than the variance of singletons from the second National Health and Nutrition Examination Survey. At the third exam, HDL-C was divided by precipitation into HDL2 and HDL3 fractions, and HDL2 was found to be the primary cause of the greater DZ total variance (DZ/MZ HDL2 variance = 2.22). The DZ/MZ variance ratio decreased 9% after adjustment of HDL2 for correlations with plasma triglycerides, alcohol consumption, smoking, exercise, and body mass index measured at the third exam. Postulated causes of the difference between MZ and DZ total variances include World War II induction screening, environmental influences unique to one zygosity, and genetic factors related to twinning. Further understanding of the etiology of this striking difference between MZ and DZ twin variance for HDL-C fractions could lead to more effective methods of decreasing the complications of arteriosclerosis.

Adult↗
PubMedDate not supplied

Genetic influences on renin, aldosterone, and the renal excretion of sodium and potassium following volume expansion and contraction in normal man.

To investigate the influence of hereditary on plasma renin activity (PRA), plasma aldosterone concentrations (PAC), blood pressure, and the renal excretion of sodium and potassium following volume expansion and contraction in normal man, we studied 37 pairs of monozygotic (MZ) and 18 pairs of dizygotic (DZ) twins. Volume expansion was achieved by the intravenous infusion of 2L normal saline; volume contraction was accomplished by a low-sodium diet and 120 mg oral furosemide. The presence of genetic variance was tested by calculating the within pair and among component estimates of genetic variance. Outpatient 24-hour-urine collections suggested that MZ and DZ twins ingested diets similar in sodium and potassium content, and failed to reveal genetic influences on the dietary preferences for these electrolytes. The PRA values suggested heritable influences during both the volume expanded and contracted state with the added stimulus of upright posture. Heritable influences were observed on PAC and were most apparent in the basal state on the day of volume expansion. An influence of heredity on blood pressure was most apparent during volume contraction. Urinary sodium excretion (UNaV), urinary potassium excretion (UKV), fractional excretion of sodium (FENa), and fractional excretion of potassium (FEK) revealed evidence of significant genetic variance under the condition of volume expansion. in that state, systolic blood pressure was directly correlated with PRA, PAC, and inversely with FENa. The data suggest that the renal regulation of sodium and potassium excretion is in part influenced by heritable factors that may in turn contribute to the development of hypertension in some individuals.

Adolescent↗
PubMedDate not supplied

An approach to the evaluation of genetic influences on factors that regulate arterial blood pressure in man.

To assess the influence of heredity on factors that help regulate the arterial blood pressure in man, we conducted sodium-loading and depletion studies in monozygotic and dizygotic twins, normotensive first-degree relatives of essential hypertensives, and in normotensive control subjects matched for age, sex, and race. Following sodium-loading, we found evidence for the influence of genetic variance on the natriuretic responses, plasma renin activity (PRA), plasma aldosterone concentrations (PA), and plasma and urinary norepinephrine. Relatives of hypertensives differed from controls in that they had higher blood pressures, greater renin values, and relatively sluggish natriuretic responses. Since renin and fractional sodium excretion values were inversely correlated in all subject groups, it is possible that the heritable influences we observed on sodium excretion were mediated by the renin-angiotensin-aldosterone system.

Adolescent↗
PubMedDate not supplied

Blood pressure response to dietary sodium restriction in normotensive adults.

Sixteen healthy, normotensive husband-wife pairs participated in a study to investigate the effect of reduction of dietary sodium intake (goal less than or equal to 60 mEq/day) on blood pressure. Sodium excretion decreased from a control average of 152.7 +/- 10.1 (SE) mEq/day to 69.5 +/- 4.5 mEq/day (p less than 0.001). Results indicated significant decreases in both systolic (p less than 0.001) and diastolic (p less than 0.001) blood pressure after a period of sodium restriction. In the entire group, there was no significant change in potassium excretion (58.4 +/- 3.2 vs 54.6 +/- 3.5 mEq/day) or body weight (76.0 +/- 2.8 vs 75.3 +/- 2.7 kg). Although there was variability in the blood pressure response, the decrease in blood pressure was significantly correlated with the magnitude of sodium restriction (r = 0.36, p less than 0.03). These results indicate that the blood pressure response to sodium restriction may not be limited to individuals with hypertension and that the response is heterogeneous in normotensive subjects.

Adult↗
PubMedDate not supplied

Micro competition enzyme linked immunosorbant assay for human apolipoprotein B.

A solid phase micro competition enzyme linked immunosorbant assay (microCELIA) was developed to measure apolipoprotein B (Apo B) in human plasma. The soluble Apo B competed with the solid phase antigen for antibody binding. After washing, alkaline phosphatase labeled goat anti-rabbit IgG antibody was added and the plates were washed and assayed. The minimal quantifiable concentration of Apo B was one mg per L. This enzyme immunoassay (EIA) yielded values which correlated with values of samples assayed in reference laboratories by radioimmunoassay (RIA) (r = 0.97) and by electroimmunoassay (r = 0.92). The electroimmunoassay overestimates the activity of hyperlipemic samples compared to microCELIA. The assay offers advantages over other existing techniques including short incubation time, high sensitivity, technical simplicity, elimination of radioisotopes, low cost, and use of a universal enzyme label.

Apolipoproteins B↗