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Biomedical subjects

R M Siervogel

Publications and source records attributed to R M Siervogel.

At least 73 records · Page 4Linked to original sources
PubMed1987

Effect of racemic epinephrine on ventilatory function in the neonate postextubation.

The use of nebulized racemic epinephrine to improve ventilatory function in the newborn postextubation was studied. Forty-five infants intubated for more than 3 days were randomized to receive racemic epinephrine by nebulization immediately postextubation or to receive only warmed, humidified gas. Measurements of air flow, esophageal pressure, tidal volume, respiratory rate, and heart rate were made before treatment and every 10 min for 1 h after treatment. Resistance was calculated from recorded data. Changes from baseline values were calculated for each time period. Analysis of variance of these variables for treatment, sex, and time main effects and their interactions, with appropriate adjustments for covariables, was performed. Although some sex interactions were seen, there were no significant time effects or interactions. This study provides no evidence that using nebulized racemic epinephrine in infants postextubation improves ventilatory function.

Administration, Inhalation↗
PubMed1984

Major gene model for the inheritance of catechol-O-methyltransferase activity in five large families.

Five large families including 1,189 individuals were each ascertained through one proband with essential hypertension. Four of the probands were white and one was black. Erythrocyte catechol-o-methyltransferase (COMT) activity was measured in 551 family members. Standard statistical methods were used to investigate sex, age, and family differences in COMT activity. Maximum-likelihood methods were used to fit mixtures of normal distributions to COMT activity. COMT activity is distinctly bimodal. Pedigree segregation analyses were performed on the untransformed COMT values, their square roots, and natural logarithms in each family. In no family and under none of the three transformations was it possible to reject the hypothesis of Mendelian transmission of a major gene with two alleles in Hardy-Weinberg equilibrium. In most cases a genetic hypothesis with complete dominance or recessiveness, or a hypothesis of equal transmission probabilities was rejected. While the different transformations had a large effect on the skewness and kurtosis of the overall distribution of the data, they had little effect on the outcome of these segregation analyses. Therefore, this study strongly supports the concept that variation in COMT activity is due in large part to the effects of a major gene.

Adult↗
PubMed1984

Linkage relationships between a major gene for catechol-o-methyltransferase activity and 25 polymorphic marker systems.

Segregation analysis has provided evidence suggesting the existence of a major gene for catechol-o-methyltransferase (COMT) activity in man. Five large families (4 Caucasian, 1 black), with a total of 1,189 individuals, were ascertained as part of a genetic study of blood pressure. Erythrocyte COMT activity and status at 25 polymorphic genetic marker loci were determined on more than 518 individuals in these pedigrees. Genetic linkage analysis of COMT with each of the 25 marker loci was performed in two ways: 1) using parameter estimates from segregation analysis of untransformed COMT activity, and 2) using parameter estimates from segregation analysis of the power transformation of the COMT activity that maximized the likelihood of the genetic hypothesis in each family. Tight and close linkage were excluded at 21 and 15 loci, respectively. A lod score of 1.27 at theta = 0.1 was found between the loci for COMT activity and phosphogluconate dehydrogenase (PGD). Transformation of the data had little effect on the outcome of the linkage analysis.

Catechol O-Methyltransferase↗
PubMed1984

Estimating the recombination frequency for the PTC-Kell linkage.

Two data sets are analyzed for linkage between the PTC and Kell blood group loci. The original report of close linkage for these loci was that of Conneally et al. (1976), where the maximum likelihood estimate of theta was 0.05. These two new data sets give a combined maximum likelihood estimate of theta m = f = 0.28. Estimating the recombination frequency for the sexes separately gave theta m = 0.29, theta f = 0.23. The combined maximum likelihood estimate over all published data sets including this report is theta m = f = 0.14, Zmax = 8.94. There is statistically significant evidence of heterogeneity among the published studies.

Blood Group Antigens↗
PubMed1984

Sibling correlations for cranial measurements from serial radiographs.

Sibling correlations are presented for nine craniofacial measurements from lateral cephalometric radiographs of participants in the Fels Longitudinal Study of Growth and their siblings. Because the data were collected serially, measurements on sibs at the same age can be compared at one-year intervals. Sibling correlations are generally lowest during the first year of life and highest as adulthood is approached, but no interpretable pattern is established during the intervening years. Most of the correlations are significantly greater than zero, and many exceed 0.5, the value expected for a completely heritable polygenic trait. This suggests that common sibling environment contributes to sibling resemblance for craniofacial dimensions in our sample.

Adolescent↗
PubMed1983

A genetic study of hyper-alpha-lipoproteinemia.

Because of its association with longevity and reduced incidence of coronary heart disease, it becomes important to find out how elevated HDL-cholesterol levels are determined. Analyses of family data from Cincinnati initially suggested environmental factors common to sibs; however, some form of dominant inheritance could not be ruled out. Reanalysis of the Cincinnati data by Iselius and Lalouel concluded against a major locus, but did identify three families as possibly segregating for a major locus. Analysis of an additional 26 kindreds from the same population in Cincinnati by Siervogel and associates concluded that a major gene could be causing familial aggregation of high density lipoprotein in white kindreds. In this analysis, we pooled all the white Cincinnati kindreds (n = 31), and investigated the familial transmission using complex segregation analysis. We failed to obtain clear evidence for major locus determination. Under the parsimonious hypothesis of no major locus, the polygenic heritability and common sibling environmental correlation were estimated as 0.531 and 0.263, respectively, consistent with other evidence.

Adult↗
PubMed1983

Iris pigmentation and AC thresholds.

Data from 160 White children were used to analyze possible associations between iris pigmentation and AC pure-tone thresholds. Iris pigmentation was graded from iris color using glass models of eyes, and AC thresholds were obtained under carefully controlled conditions. Analyses of variance using two groupings of iris color grades showed no evidence of an association between iris color grade and AC thresholds. Furthermore, inspection of arrays of the actual glass eye models, in conjunction with the order of mean thresholds at each test frequency, did not indicate the presence of an association between iris color grades and thresholds. It was concluded that while iris pigmentation may be related to some aspects of hearing ability, it does not appear to be related to AC thresholds in children.

Adolescent↗
PubMed1983

Cardiovascular response to a mentally stressful stimulus.

The purpose of this study was to investigate multivariable cardiovascular responses to a non-mathematical mental task. Fifty-two subjects, 8 to 69 years of age, were monitored at rest and while attempting to solve a Raven's matrix test without prodding or pressure from the experimentors. Adults (greater than or equal to 18 years) had higher blood pressures (BP) and longer pre-ejection periods (PEP) at rest than did the children. Women had higher resting heart rates (HR) than men. The task induced significant increases in systolic and diastolic BP and HR in adults and children, with the adults exhibiting larger BP responses. During the stressful stimulus significant decreases in left ventricular ejection time occurred in men and women, and significant increases in forearm blood flow occurred in men. The stability in PEP during the stressful period when both BP and HR were increased is evidence of enhanced contractility brought on by the stress. In general, men and women responded similarly. Thus, even a mild, non-mathematical stress of short duration elicits the multiple cardiovascular responses, including increases in BP, HR, muscle blood flow, and contractility, which are observed with more threatening tasks.

Adolescent↗
PubMed1982

Subcutaneous fat distribution in males and females from 1 to 39 years of age.

Subcutaneous fat thicknesses measured in two longitudinal studies, the Denver Growth Study and the Melbourne Growth Study, were examined to determine 1) if one site of subcutaneous fat measurement is more representative than another of the body's subcutaneous fat layer, 2) if some measurements of subcutaneous fat from specific body areas are more representative of the subcutaneous fat layer than others, and 3) if there are sex and age differences in intersite relationships. Data from the Denver Study include skinfold thicknesses from 10 sites measured serially at annual ages from 4 to 39 yr and radiographic fat thickness measured at five sites at annual ages from 1 to 18 yr. In the Melbourne Study, five skinfold thicknesses were measured serially in children from 2 to 15 yr of age. Relatively low intersite communalities during the prepubertal years suggest a tendency in each sex for considerable site-to-site variation during this period. However, immediately before puberty and throughout adolescence, high communalities indicate that the thickness of subcutaneous fat at any site is highly related to thickness at all other sites. After puberty and into the mid-20's, there is a reoccurrence of greater site-to-site variability. This higher degree of variation continues into early middle age only in women, implying that more changes occur in their subcutaneous fat, that differentially affect various parts of the body, than in men.

Adipose Tissue↗
PubMed1982

Changes in adipocyte cellularity in children ten to 18 years of age.

Adipocyte size and number, and total body fat were collected serially from boys and girls living in South-western Ohio. Sex-specific annual increments were computed across age for each of these variables. During adolescence, the boys had a near zero mean increment in total body fat, but the girls had a positive mean increment in total body fat. In both the boys and girls, there were negative mean increments in adipocyte size and positive mean increments in adipocyte number. Sex-specific age-to-age correlations are statistically significant for adipocyte number and total body fat but not for adipocyte size. These data indicate that increases in total body fat during adolescence may be due to increases in adipocyte number and that annual increments in adipocyte size may provide little information in regard to changes in total body fat.

Adipose Tissue↗
PubMed1981

Size and number of adipocytes and measures of body fat in boys and girls 10 to 18 years of age.

In 111 boys and girls, 10 to 18 yr of age, body density was measured by underwater weighing, and the size of adipocytes in adipose tissue from the buttocks was measured by the osmium tetroxide method. From these two measures, estimates of percentage body fat, total body fat, and adipocyte number were computed for most of the children. Their skeletal age was also calculated by an acceptable method. Across chronological age, the girls have significantly larger mean values of total and percentage body fat and larger and more numerous adipocytes than the boys. The mean number of adipocytes in each sex is within adult levels, as is the mean size of the adipocytes in the girls. The boys' mean adipocyte size is below the adult level. There are negative, significant correlations between percentage body fat and chronological or skeletal age in the boys, and positive significant correlations between total body fat and chronological or skeletal age in the girls. Also, adipocyte size is positively correlated with percentage body fat but only in the boys. With the effects of chronological age removed, percentage body fat was significantly and negatively correlated with skeletal age in boys only. All other correlations among the variables were not statistically significant.

Adipose Tissue↗
PubMed1981

Adipocytes and adiposity in adults.

Measures of adipocyte size and body density were collected from 217 nonobese adults 20 to 50 yr of age, and estimates of total body fat, percentage body fat, and adipocyte number were calculated. Women had a greater percentage body fat than men in every age group except the oldest. Women had significantly greater amounts of total body fat and larger adipocytes than men in the 20- to 24-yr group, but men had significantly greater amounts of total body fat than the women in the 45- to 50-yr group. Adipocyte number, total body fat, and percentage body fat are each positively correlated with age in both sexes. Adipocyte size is not correlated with age but is positively correlated with total and percent body fat in men and women irrespective of age. These cross-sectional data suggest that adipocyte number, rather than being stable during adulthood, increases with age and is associated with corresponding increases in total and percentage body fat.

Adipose Tissue↗
PubMed1981

A new ventricular-performance variable using electrocardiogram and carotid pulse contour derivative.

The pre-ejection period (PEP) of systole is a widely used, non-invasive index of ventricular performance. For precise measurements, simultaneous recordings are required from which the Q-wave on the electrocardiogram, second heart sound on the phonocardiogram, and upstroke and incisura of the carotid pulse contour are discretely identifiable and temporally accurate. This is frequently difficult to accomplish. We, therefore, have compared 2 other noninvasive indices of ventricular performance for correlation with PEP in 17 female and 18 male subjects while supine and during head-up tilt. We also examined similarity of these indices to PEP in correlations with heart rate and blood pressure and compared them for ease in monitoring and precision in measurement. The ratio of the peak amplitude of the carotid pulse contour derivative to its total amplitude (DAR) is easier to monitor and more reliably measured than PEP; however, it is poorly correlated with PEP. Time from electrocardiographic Q-wave to peak dD/dt (Q-MAX) is also easier to monitor and somewhat more reliably measured than PEP. Although correlations of PEP and Q-MAZ with subject age are dissimilar, Q-MAX is correlated with PEP in supine and tilted subjects; the 2 variables are similarly correlated with heart rate and arterial pressure; and in 6 subjects both variables were prolonged after intravenous administration of propranolol-hydrochloride. We, therefore, propose Q-MAX as an alternative measure of ventricular performance.

Adolescent↗