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Biomedical subjects

W R Clarke

Publications and source records attributed to W R Clarke.

At least 73 records · Page 4Linked to original sources
PubMed1988

Factors affecting the relationship between childhood and adult cholesterol levels: the Muscatine Study.

A group of 2,446 subjects initially examined at 8 to 18 years of age were reexamined as young adults of 20 to 25 or 26 to 30 years of age. Measurements of cholesterol, height, weight, and triceps skinfold thickness were obtained during childhood. Lipids, lipoprotein fractions, and family history, as well as medication, alcohol, and tobacco use, were determined during the adult examination. Elevated levels of cholesterol during childhood were associated with elevation in adult life. Obesity acquired in adolescence and the young adult years, oral contraceptive use, and cigarette smoking had deleterious effects on adult cholesterol levels and lipoprotein fractions.

Adolescent↗
PubMed1987

Enhanced forearm blood flow during mental stress in children of hypertensive parents.

This study compared changes in forearm blood flow, forearm vascular resistance, blood pressure, and heart rate elicited by mental stress (mental arithmetic) in 12 adolescents with a hypertensive parent and 13 age-matched adolescents with normotensive parents. The two groups did not differ in resting forearm blood flow, forearm vascular resistance, heart rate, or blood pressure. During mental stress, children with a family history of hypertension had a significantly greater increase in forearm blood flow than did children of normotensive parents (+37.5 +/- 8.0 vs +12.8 +/- 7.5%; p less than 0.05) and a trend toward reduced forearm vascular resistance (p = 0.08). Mental stress significantly increased systolic blood pressure (p less than 0.0001), diastolic blood pressure (p less than 0.001), and heart rate (p less than 0.03) in both groups. The blood pressure and heart rate responses to stress were not significantly different between groups. There was no evidence of a prolonged response or a different pattern of recovery in children with a family history of hypertension. This study indicates that regional blood flow responses underlying similar blood pressure increases during mental stress may be different in adolescents with and without a family history of hypertension.

Adolescent↗
PubMed1986

Familial aggregation of type A behavior.

This research examined the relationship of children's Type A behavior pattern, as measured by the Matthews Youth Test for Health, to parents' Type A behavior pattern, as measured by the Jenkins Activity Survey, Form C. A total of 115 families with boys and 106 families with girls enrolled in the fourth through sixth grades participated. There were no significant correlations between the Pattern A scores of fathers and those of their children, but there was evidence for a maternal influence on the development of children's Type A behavior. The results are compared with results from studies of familial aggregation previously reported in the literature.

Aggression↗
PubMed1986

Aggregation of blood pressure in the families of children with labile high systolic blood pressure. The Muscatine Study.

The aggregation of systolic blood pressure, diastolic blood pressure, and heart rate is compared among the relatives of three groups of index children: children with low systolic blood pressure (less than the 5th percentile), middle range systolic blood pressure (between the 5th and 95th percentiles), or labile high blood pressure (above the 95th percentile when first sampled but below the 95th percentile when resampled four to six months later). Both systolic and diastolic blood pressures aggregate more strongly in the families of children with labile high systolic blood pressure than in the families of children with middle or low range systolic blood pressure. The degree of aggregation of heart rate does not differ among the three groups. Since blood pressures aggregate so strongly in families of children with labile high systolic blood pressure, study of these children and their families may yield important information about the etiology of hypertension.

Adolescent↗
PubMed1986

Changes in ponderosity and blood pressure in childhood: the Muscatine Study.

This paper describes the association between longitudinal changes in blood pressure and changes in measures of ponderosity. Between 1971 and 1981, 2,925 Muscatine, Iowa schoolchildren were measured at least once between ages 6 and 15 years and again between ages 15 and 18. The study shows that change in ponderosity is associated with change in blood pressures; children whose ponderosity decreases relative to their peers usually exhibit a similar drop in their systolic and diastolic blood pressures, while children who gain in ponderosity show a similar gain in their blood pressures. The magnitude of change in blood pressure is related to amount of ponderosity gain or loss and does not depend on initial blood pressure. These data suggest that for obese children weight loss might be an effective method for reducing their blood pressure.

Adolescent↗
PubMed1986

The relations between type A behavior, clinically relevant behavior, academic achievement, and IQ in children.

The relation of Type A behavior to IQ, academic achievement, and several clinically relevant dimensions of behavior in children was assessed in 873 fourth, fifth, and sixth graders by means of the Matthews Youth Test for Health (MYTH), the Cognitive Abilities Test (CAT), the Iowa Tests of Basic Skills (ITED), and the teachers' form of the Missouri Children's Behavior Checklist (MCBC-T). The MYTH and its competitiveness and impatience-aggression subscales were found to be differentially related to academic achievement and to account for a small but significant portion of the variance in achievement not accounted for by IQ. The subscales of the MYTH were found to be highly correlated with several clinically familiar dimensions of children's behavior. The significance of these findings for the construct validity of the MYTH is discussed.

Achievement↗
PubMed1986

Tracking of blood pressure during childhood: the Muscatine Study.

Four thousand three hundred and thirteen children beginning at five to fourteen years of age have been examined on three to six occasions in Muscatine, Iowa on alternate years. To compare blood pressures throughout the period of observation each value was expressed as a percentile rank. For each subject the average percentile rank (level), the trend in rank and the variability over time were calculated. Values for height, weight, relative weight and triceps skinfold thickness measurements were expressed in the same fashion. The relationship between average rank of blood pressure and average rank of body size as well as between trend of blood pressure and trend of body size percentiles were significant (p less than .05). These observations indicate the importance of relative rate of growth in the establishment of the rank order of blood pressure.

Adolescent↗
PubMed1986

Hemodynamics in childhood hypertension.

Children with elevated systolic blood pressure have a wide range of cardiac output. We investigated the mechanisms regulating resting and exercise blood pressure in 264 children who were selected from the low, middle, and upper quintile of the distribution of blood pressure of an entire school population. We identified patterns of response to exercise that correlated both with resting cardiac output and resting blood pressure. During isometric exercise, systolic blood pressure adjusted for age and body size increased in all groups. The low group mean pressure remained significantly lower than the high group's pressures throughout the entire exercise period. Body size adjusted group systolic and diastolic blood pressure level differences existed during dynamic exercise. The product of the systolic blood pressure times the heart rate in the high blood pressure group was significantly higher throughout dynamic exercise than in the other two groups. Elevated resting resistance was correlated with elevated resistance during isometric exercise and elevated diastolic blood pressure during dynamic exercise. Cardiac index had a significant negative correlation to age (r = -0.58) at all levels of blood pressure. This observation, in children, lends some support to the concept of evolution from a hyperkinetic circulation in early childhood to a circulation with lower cardiac output and more elevated systemic vascular resistance at an older age.

Age Factors↗
PubMed1986

Lipoproteins in the progeny of young men with coronary artery disease: children with increased risk.

The authors studied 173 progeny from 63 families in which the father had angiographically diagnosed coronary artery disease by 50 years of age. To assess the nature of the coronary risk factors in these families, we measured their height and weight to calculate Quetelet index (wt/ht2), BP, fasting plasma cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol were measured in the affected fathers, their wives, and their progeny. These values were compared with age- and sex-specific values from the Lipid Research Clinic data. Sixty-five percent of the affected fathers and 51% of the progeny had elevated triglyceride, elevated low-density lipoprotein cholesterol, diminished high-density lipoprotein cholesterol, or combinations thereof. The distribution of the lipids and lipoproteins in the children bore a close resemblance to those observed in the affected fathers. A significant number of the mothers had diminished high-density lipoprotein cholesterol, which was attributed to their obesity. Screening the progeny of young coronary artery disease patients is therefore highly productive in identifying young people at excessive risk for future coronary artery disease. Early identification of this young high-risk population offers an opportunity for early initiation of preventive measures.

Adolescent↗
PubMed1985

Effects of acidosis on fetal and maternal blood coagulation: a fetal lamb model.

The effects of fetal acidosis (mean pH 6.93) on fetal and maternal blood coagulation were measured. Test results from 10 fetal lambs and mother ewes (127 +/- 2 days mean gestation) before and after fetal lactic acid infusions were compared to test results from eight control fetal lambs and mother ewes (127 +/- 3 days mean gestation) before and after control glucose infusion. Significant changes found in acidotic fetal lambs not seen in control fetuses included an increase in the white blood cell count (mean 2800/mm3 before to 3600/mm3 after acidosis; p = 0.0009), a shortening of the thrombin time (mean 17.8 s before to 11.2 s after acidosis; p = 0.0001), and decreases in the activities of factor V (mean 57% before to 37% after acidosis; p = 0.0014) and factor IX (mean 35% before to 29% after acidosis; p = 0.0128). There was also a reduction in the concentration of fibrinogen (mean 147 mg/100 ml before to 125 mg/100 ml after acidosis; p = 0.0492) but no significant changes in the levels of fibrin monomer, fibrinogen/fibrin degradation products, or antithrombin III. In vitro exposure of five different fetal whole blood samples to a pH of 6.9 for 2 h at 37 degrees C did not result in significant changes in any of the coagulation factor activities. A significant decrease in the level of factor V was also found in the mother ewes of the acidotic fetuses (mean 141% before to 113% after acidosis; p = 0.006) and a decrease in the level of maternal factor IX approached significance (mean 119% before to 102% after acidosis; p = 0.0564).(ABSTRACT TRUNCATED AT 250 WORDS)

Acidosis↗
PubMed1985

Assessing children's blood pressure--considerations of age and body size: the Muscatine Study.

Blood pressure was assessed in 4,207 children, aged 5 to 18 years, examined in the schools of Muscatine, Iowa during 1981. Overall, 69.9% of the age-sex-specific quintiles and height-sex-specific quintiles of systolic blood pressure were identical. In only 1.0% of children did these quintiles differ by more than one. Children whose blood pressure was in the highest quintile for both age and height were more obese than their peers. Those whose blood pressure was high for age but not for height were proportionately taller and heavier than their age peers. Children whose blood pressure was high for height but not for age were older, shorter, and lighter. Thus, having precocious levels of blood pressure for age during childhood is associated with excessive body weight or precocious height, whereas having high blood pressure for height but not for age is associated with being short for age. The latter suggests that age may be a factor independent of height and weight affecting blood pressure level in childhood. These relationships of body size and age to blood pressure must be considered when evaluating children's blood pressure levels in the clinical setting, and a technique for doing so is presented.

Adolescent↗
PubMed1984

Level, trend, and variability of blood pressure during childhood: the Muscatine study.

On alternate years from 1970 to 1981 blood pressure has been measured in school children living in Muscatine, Iowa. A total of 4313 children beginning at 5 to 14 years of age have been examined on three to six occasions. To compare blood pressures throughout the period of observation, each value was expressed as a percentile rank. For each subject the average percentile rank (level), the trend in rank, and the variability over time were calculated. Values for height, weight, relative weight, and triceps skinfold thickness were expressed in the same fashion. The relationship between average rank of blood pressure and average rank of body size as well as between trend of blood pressure and trend of body size percentiles were significant (p less than .05). These observations indicate the importance of relative rate of growth in the establishment of the rank order of blood pressure. Using the variables of level, trend, and variability, we identified groups of children who appear to be consistently tracking toward future hypertension: 233 (5.4%) children, whose systolic levels were in the upper quintile with either a flat or rising trend and low variability, and 280 (6.0%) children with systolic levels in the lower four quintiles with high trend and low variability. In addition there were 321 (7.4%) children whose mean systolic levels were in the upper quintile with high variability and who thus resemble adults with labile hypertension. There were similar numbers of children with diastolic pressures showing these features.

Adolescent↗
PubMed1984

Vaccination of bovines against schistosomiasis japonica with highly irradiated schistosomula in China.

Vaccination of Chinese bovines (cattle and buffaloes) against schistosomiasis japonica with 36 kR gamma-irradiated schistosomula was done for laboratory challenge and for field trials in China. Altogether, 61 bovines were used. All experimental animals were vaccinated 2-3 times with 10,000 irradiated schistosomula per time. For the laboratory challenge, all experimental and control cattle were challenged with 500 normal cercariae and each buffalo, with 2,000 cercariae. The laboratory-challenged bovines were killed after 54-57 days of challenge; the bovines for the field trial in the lightly endemic area, after 5 months in the field; and the bovines for the field trial in the heavily endemic area, after 58-63 days. When the animals were killed, the number of mature worms in the vaccinated (experimental) and non-vaccinated (control) animals was recorded and the percentage of worm reduction in each group was calculated. The first group, consisting of three vaccinated and three non-vaccinated cattle, was given a laboratory challenge; the worm reduction was 71.6%. The second group, consisting of two vaccinated and three non-vaccinated buffaloes, was also given a laboratory challenge; the worm reduction was 74.4%. The third group, consisting of seven vaccinated and eight non-vaccinated buffaloes, was utilized in a field trial in a lightly endemic area; the worm reduction was 75.6%. The fourth group, consisting of eight vaccinated and nine non-vaccinated cattle, and the fifth group, consisting of nine vaccinated and nine non-vaccinated buffaloes, were pastured in a heavily endemic area. The worm reduction was 65.1% in the fourth group and 75.7% in the fifth group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The international standardization of the medical certification of civil aircrew.

The extremely heterogeneous nature of the various peoples and states of today's world makes the development of a satisfactory set of medical standards for the certification of civil aircrew extremely difficult. This difficulty is compounded by the varying roles aviation plays in different parts of the world. Essential to the understanding of this difficulty is a comprehension of the concept of the sovereignty of nations. Emphasis on aviation medical standards is affected by the variation in health care priorities seen amongst the worldwide community of nations. Annex 1 to the Convention on International Civil Aviation sets regulations and recommendations for aircrew licensure. The capability of the International Civil Aviation Organization (ICAO) to enforce regulations is restricted by the same factors which restrict the power of any supernational organization. Nonetheless ICAO remains the most effective means available for achieving the diplomatic consensus so essential to the development of international standards.

Aerospace Medicine↗
PubMed1983

The ankle injury--indications for the selective use of X-rays.

The radiograph is rapidly superseding the clinical examination as the diagnostic tool for acute ankle injuries. Twenty-four independent variables which might help distinguish between soft tissue injuries and fractures at the ankle were identified and then used prospectively to study 150 consecutive patients with ankle injuries. Nineteen patients had fractured ankles (12.7 per cent) and 131 (87.3 per cent) had soft tissue injuries. Only the patient's ability to bear weight on the injured ankle and the presence of tenderness over the lateral aspect of the ankle below the malleolus proved to be helpful. When these 2 signs were present together, regardless of all other variables, there was a 97.5 per cent probability of soft tissue injury P less than 0.005). This study suggests that careful patient assessment will permit more discriminating use of ankle X-rays.

Adolescent↗
PubMed1983

Community differences in blood pressure levels and drinking water sodium.

In a study conducted in 1980-1981, the authors surveyed over 2000 school children in eight Iowa communities whose drinking water sodium levels varied from less than 10 to greater than 300 mg/liter. Children in grades 2-5 had four blood pressures, skinfold, height, weight, and heart rates measured while in school. The range of the difference between mean blood pressures by community was less than 4 mmHg for systolic and fourth phase diastolic. An association between blood pressure and water sodium level was not demonstrated before or after adjustment for covariates. In a subsample of over 200 households in four communities, the authors examined the relationship of blood pressures in adults to water sodium level. Blood pressure means for adults by community varied less than 4 mmHg for systolic and diastolic measurements. This variance was not explained by sodium level in the drinking water. These surveys do not substantiate previous reports of a positive association between drinking water sodium levels and blood pressure levels.

Adult↗
PubMed1983

Vaccination against bovine schistosomiasis japonica with highly X-irradiated schistosomula.

Cercariae of the Chinese mainland strain of Schistosoma japonicum were used. Eighteen cattle, divided into six groups of three each, were immunized with schistosomula transformed from cercariae exposed to three different doses of X-irradiation (24, 36, and 48 kR). The immunization was given either once, twice, or thrice, and the number of immunizing schistosomula was 10,000 or more in each immunization. The immunized cattle were challenged with 500 normal cercariae. Five native cattle were similarly infected with normal cercariae as controls. All cattle were killed 32-33 days after challenge or infection, and the worms were obtained by perfusion. The mean worm reduction in the 18 experimental animals varied from 42.1 to 96.0%. The mean percent worm reduction of the six experimental groups varied from 54.8 to 87.1. The reduction was greater with increasing numbers of immunizations, and was higher in the groups immunized with schistosomula exposed to 36 kR than in those exposed to 24 or 48 kR. Statistical analyses showed that all immunized groups yielded significantly fewer worms than controls. However, the three doses of X-irradiation (24, 36, and 48 kR) had no significant effect for a fixed number of immunizations (1, 2, or 3). The means for both two and three immunizations were significantly different from the mean for one immunization, although they were not significantly different from each other.

Animals↗