PubMed Health⌕ Search

Biomedical subjects

R B Dell

Publications and source records attributed to R B Dell.

At least 19 recordsLinked to original sources
PubMed1992

Surgical management of the infant with coarctation of the aorta and ventricular septal defect.

Clinical and cardiac catheterization data were collected from 39 infants with coarctation of the aorta and ventricular septal defect, 31 of whom were initially managed only by surgical repair of coarctation. Data were analyzed to determine mortality, morbidity, outcome and factors that might predict survival or the need for septal defect closure. Of the eight patients who did not require surgical treatment before 3 months of age, seven underwent coarctation repair alone at a mean age of 2.3 years. Of the 23 infants managed with coarctation repair alone, before age 3 months, 9 needed no additional surgical treatment and 6 required early and 8 required late repair of the ventricular septal defect. Seven infants underwent coarctation repair and simultaneous pulmonary artery banding and one eventually required debanding after spontaneous closure of the septal defect. The overall mortality rate in this series was 10.3% (mean follow-up time 5.7 years). Of 39 infants, 16 (41%) never required a second operation for ventricular septal defect closure. For patients who had only coarctation or coarctation repair with pulmonary artery banding at less than 3 months of age, ventricular septal defect size was categorized as small (less than 0.5 cm/m2), moderate (less than 1 cm/m2) or large (greater than 1 cm/m2) on the basis of defect size at operative repair or echocardiographic or angiographic assessment. Defect size did not necessarily correlate with the need for operative repair.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Coarctation↗
PubMed1992

Reducing total dietary fat without reducing saturated fatty acids does not significantly lower total plasma cholesterol concentrations in normal males.

Forty-eight healthy male students ate an average American diet (AAD) with 37% of calories from fat and 16% from saturated fatty acids for 3 wk. During the next 7 wk, one-third of the students continued to eat the AAD, one-third switched to a 30%-fat diet with 9% saturated fatty acids (Step 1 diet), and one-third switched to a 30%-fat diet with 14% saturated fatty acids (Sat diet). The Step 1 group had a significant reduction in plasma total cholesterol (TC) (0.36 +/- 0.37 mmol/L) compared with the AAD group (0.07 +/- 0.39 mmol/L) and the Sat group (0.08 +/- 0.25 mmol/L). The Sat group did not differ from the AAD group. Changes in low-density-lipoprotein (LDL) cholesterol paralleled changes in total cholesterol. High-density-lipoprotein cholesterol fell significantly in the Step 1 group (0.11 +/- 0.08 mmol/L) compared with the AAD group. Plasma triglycerides did not differ between groups at the end of the randomized periods. In summary, reduction of dietary fat intake from 37% to 30% of calories did not lower plasma total and LDL cholesterol concentrations unless the reduction in total fat was achieved by decreasing saturated fatty acids.

Adult↗
PubMed1991

Family history fails to identify many children with severe hypercholesterolemia.

Optimal strategies for identifying children with hypercholesterolemia have not been established. Several groups have advocated that testing of serum cholesterol levels be limited to those children who have family histories of hyperlipidemia or premature coronary heart disease. We studied the ability of comprehensive family histories to identify children with hyperlipidemia in a group of 114 children (mean age, 8 +/- 4 years) who were referred for treatment of hypercholesterolemia. A positive family history was defined according to guidelines of the American Academy of Pediatrics. The mean fasting total cholesterol in the children was 5.74 +/- 1.42 mmol/L (222 mg/dL). Family history was negative for hypercholesterolemia or premature coronary heart disease in 22 (22%) of 100 children with total cholesterol levels greater than the 75th percentile for their ages, in 13 (18.3%) of 71 children with total cholesterol levels greater than the 95th percentile for their ages, and in four (11.8%) of 34 children with presumed heterozygous familial hypercholesterolemia. Of the 78 children who had both hypercholesterolemia and positive family histories, hyperlipidemia was reported in 72 families, whereas premature heart disease was reported in only 27. We conclude that in a population of children referred because of known hypercholesterolemia, a detailed family history not only fails to identify many children with mild hypercholesterolemia, but also fails to identify a significant proportion of children with markedly elevated cholesterol levels. Additionally, in families of children with hypercholesterolemia, a history of hyperlipidemia is more common than a history of premature heart disease.

Adolescent↗
PubMed1990

Reduction of plasma cholesterol levels in normal men on an American Heart Association Step 1 diet or a Step 1 diet with added monounsaturated fat.

The design of diets to achieve optimal changes in plasma lipid levels is controversial. In a randomized, double-blind trial involving 36 healthy young men, we evaluated the effects on plasma lipid levels of both an American Heart Association Step 1 diet (in which 30 percent of the total calories were consumed as fat: 10 percent saturated, 10 percent monounsaturated, and 10 percent polyunsaturated fats, with 250 mg of cholesterol per day) and a monounsaturated fat-enriched Step 1 diet (with 38 percent of the calories consumed as fat: 10 percent saturated, 18 percent monounsaturated, and 10 percent polyunsaturated fats, with 250 mg of cholesterol per day). The effects of these diets were then compared with those of an average American diet, in which 38 percent of the total calories were consumed as fat: 18 percent saturated, 10 percent monounsaturated, and 10 percent polyunsaturated fats, with 500 mg of cholesterol per day. The men consumed the average American diet for 10 weeks before random assignment to one of the two Step 1 diets or to continuation of the average diet for an additional 10 weeks. Caloric intake was adjusted to maintain a constant body weight. As compared with the mean (+/- SD) change in the plasma total cholesterol level in the group that followed the average American diet throughout the study (-0.05 +/- 0.36 mmol per liter), there were statistically significant reductions (P less than 0.025) in the plasma total cholesterol level in the group on the Step 1 diet (-0.37 +/- 0.27 mmol per liter) and in the group on the monounsaturated fat-enriched Step 1 diet (-0.46 +/- 0.36 mmol per liter). There were parallel reductions in the plasma low-density lipoprotein cholesterol levels in these two groups. Neither the plasma triglyceride levels nor the high-density lipoprotein cholesterol concentrations changed significantly with any diet. We conclude that enrichment of the Step 1 diet with monounsaturated fat does not alter the beneficial effects of the Step 1 diet on plasma lipid concentrations.

Adult↗
PubMed1990

Growth, nutrient retention, and metabolic response of low-birth-weight infants fed supplemented and unsupplemented preterm human milk.

Growth, nutrient retention, and metabolic response of low-birth-weight infants fed human milk provided by their mother; this milk supplemented with bovine milk protein, calcium, phosphorus, and sodium; or pasteurized term human milk with the same supplement were monitored from the time desired intake was tolerated until weight reached 2200 g. The supplement resulted in greater rates of weight gain (20.5 +/- 2.3 vs 16.4 +/- 2.2 g.kg-1.d-1) and nitrogen retention (353 +/- 76 vs 270 +/- 53 mg.kg-1.d-1), increase in plasma transthyretin (TTR) concentration (7 +/- 16 vs -3 +/- 9 mg.L-1.wk-1), a higher mean plasma albumin concentration (34 +/- 3 vs 32 +/- 4 g/L), and a higher plasma TTR concentration at discharge (100 +/- 22 vs 75 +/- 24 mg/L). All these variables correlated significantly with total nitrogen intake, suggesting that the differences are attributable to the protein content of the supplement. The supplement also resulted in greater rates of calcium and phosphorus accretion but the plasma alkaline phosphatase activity of the supplemented vs the unsupplemented groups did not differ.

Alkaline Phosphatase↗
PubMed1990

Model for the kinetics of imipramine and its metabolites in adolescents.

A kinetic model for imipramine (IMI) has been developed, based upon a study of 16 teenagers who received IMI 4-5 mg/kg/day for treatment of a major depressive disorder. Serial measurements of plasma concentrations of IMI, desmethylimipramine (DMI), 2-hydroxy-IMI, and 2-hydroxy-DMI were made. Mean residence times, volumes of distribution, clearances of IMI and DMI, and rate constants for formation and elimination of the hydroxy metabolites were determined from a multicompartment model fitted to the concentration-time data. Mean residence time for DMI was significantly longer than for IMI (47.1 +/- 21.2 vs. 13.4 +/- 4.8 h, p less than 0.001). A different volume of distribution for IMI and DMI was not supported by the data. Clearance of DMI was considerably slower than that of IMI (0.67 +/- 0.45 vs. 2.18 +/- 1.33 l(kg.h), p less than 0.001). A statistically significant increase in mean residence time with increasing age during adolescence was found (r = 0.57, p less than 0.05).

Adolescent↗
PubMed1990

Lack of effect of lovastatin therapy on the parameters of whole-body cholesterol metabolism.

UNLABELLED: The effects of lovastatin therapy on the parameters of body cholesterol metabolism were explored in nine hypercholesterolemic patients. Long-term cholesterol turnover studies were performed before therapy, and were repeated after 15 mo of lovastatin therapy (40 mg/d) while continuing on therapy. The major question addressed was whether a reduction in plasma cholesterol level with lovastatin would be associated with a reduction in the whole-body production rate of cholesterol or with the sizes of exchangeable body cholesterol pools as determined by the three-pool model of cholesterol turnover. The mean plasma cholesterol level decreased 19.4% (from 294 to 237 mg/dl), and low-density lipoprotein cholesterol decreased 23.8% (from 210 to 159 mg/dl) with lovastatin therapy. Changes in high-density lipoprotein cholesterol level were not significant. The cholesterol production rate did not change significantly with therapy (1.09 +/- 0.10 [mean +/- S.D.] vs. 1.17 +/- 0.09 g/d). By comparison, colestipol and niacin treatment in three other subjects more than doubled the cholesterol production rate (1.14 +/- 0.28 vs. 2.42 +/- 0.34 g/d). Thus, hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibition by lovastatin at the therapeutic dose used here did not change the steady-state rate of whole-body cholesterol synthesis. Despite the changes in plasma cholesterol levels, no significant changes were seen in the values of M1, of M3 or of Mtot, the sizes of the pools of rapidly, of slowly, and of total body exchangeable cholesterol. CONCLUSION: lovastatin therapy to lower plasma cholesterol does not lead to corresponding reductions in body cholesterol pools or to a reduction in the rate of whole-body cholesterol synthesis. In the new steady state that exists during long-term lovastatin therapy, along with increased expression of the genes for HMG-CoA reductase and the LDL receptor, the body compensates for the effects of the drug so that cholesterol production rate and tissue pool sizes are not changed from pretreatment values.

Adult↗
PubMed1988

Growth, nutrient retention, and metabolic response in low birth weight infants fed varying intakes of protein and energy.

Growth, nutrient retention, and metabolic response were determined in low birth weight (LBW) infants fed daily protein and energy intakes, respectively, of 2.8 gm/kg and 119 kcal/kg (group 1), 3.8 gm/kg and 120 kcal/kg (group 2), and 3.9 gm/kg and 142 kcal/kg (group 3). The mean rates of both weight gain and nitrogen retention in group 1 were somewhat greater than intrauterine rates; plasma concentrations of transthyretin and albumin also were acceptable. Thus the lower protein intake appeared to be adequate. On the other hand, the rates of weight gain and nitrogen retention in groups 2 and 3 were greater than those in group 1, supporting the efficacy of the higher protein intake with respect to growth. However, blood urea nitrogen and plasma amino acid concentrations also were higher in groups 2 and 3; both were higher in group 2 than in group 3, reflecting the positive effect of the higher energy intake on protein utilization. This observation, combined with data from an earlier study, indicates that protein intakes in excess of 3 gm/100 kcal will not be utilized completely. Energy expenditure in group 3 was greater than in group 1 but not group 2, raising the possibility that protein intakes not utilized completely contribute to diet-induced thermogenesis. The higher energy intake in group 3 vs group 2 did not affect rate of weight gain significantly, but energy storage in group 3, and hence fat accretion, was greater than that of other groups. In all groups the ratio of protein accretion to fat accretion reflected dietary proportions of protein and energy.

Child Development↗
PubMed1988

Pediatric parenteral amino acid mixture in low birth weight infants.

A mixture of amino acids designed to maintain normal plasma amino acid concentrations in infants and children requiring parenteral nutrition was evaluated in 28 low birth weight (LBW) infants (birth weight, 750 to 1750 g; postnatal age, 1 to 4 weeks) who required parenteral nutrients for optimal nutritional management. Sixteen babies received only parenteral nutrients for five to 21 days. Ten of these received a typical regimen by peripheral vein (1.91 +/- 0.16 g/kg/d of amino acids and 44.7 +/- 4.4 kcal/kg/d) and six received a typical regimen through a central vein (2.39 +/- 0.11 g/kg/d of amino acids and 95.9 +/- 14.5 kcal/kg/d). Mean weight gain of the peripheral vein subgroup was 10.3 +/- 10.6 g/kg/d; mean nitrogen balance was 230 +/- 66 mg/kg/d. Both the mean rate of weight gain (17.2 +/- 5.1 g/kg/d) and the mean rate of nitrogen retention (267 +/- 49 g/kg/d) of the central vein subgroup were similar to intrauterine rates. In these two subgroups as well as the total population, plasma concentrations of all amino acids except phenylalanine were within the 95% confidence limits of the plasma concentrations observed in LBW infants fed sufficient amounts of human milk to result in a rate of weight gain similar to the intrauterine rate. However, although plasma tyrosine and cyst(e)ine concentrations were within the 95% confidence limits of the plasma concentrations goals, the LBW infant's ability to use N-acetyl-L-tyrosine and cysteine HCl appears to be even less than that of the term infant and older child. In toto, these data support the efficacy of the amino acid mixture evaluated for LBW infants. Of equal importance, they suggest that the LBW infant's ability to use parenterally delivered amino acids is not as limited as commonly thought.

Amino Acids↗
PubMed1988

Microdistribution and local dosimetry of 226Ra in trabecular bone of the beagle.

Sections of lumbar vertebral bodies of young adult beagle dogs have been analyzed autoradiographically to characterize and quantify the local distribution of 226Ra by means of a scanning microscope photometer. The animals received a single injection of 355 kBq/kg body weight and were serially sacrificed at 5 to 1381 days postinjection. Hotspot concentrations decreased from about 51 kBq/g bone at 5 days to 20 kBq/g at 1381 days postinjection. The diffuse concentration changed from 8.3 to 1.9 kBq/g. The mean 226Ra concentration in the trabecular areas scanned was initially higher and at the end of the observation period lower than the average calculated for the whole lumbar vertebral column. Density and area of, and fraction of bone activity in, hotspots virtually remained constant. With time hotspots tended to become translocated into bone volume. Mean dose rates to lining cells from both hotspots and diffuse labels decreased from about 210 mGy/d at early postinjection times to 105 mGy/d. This corresponds to 2.5 to 1.1 times the average skeletal dose rate. A discussion of the level of irradiation in terms of hit frequencies shows that osteoblasts in the initial phase of hotspot formation receive about 60 hits to their nucleus for the duration of bone formation. After about 6 months, however, the 226Ra concentration in new bone and the corresponding hit frequency appears to be low enough that interference with bone formation is unlikely. Morphometric measurements showed that abnormal bone accretion and thickening of trabeculae occurred. This was interpreted as an imbalance between bone formation and resorption. Both formation and resorption seem to be substantially lowered compared to control animals.

Animals↗
PubMed1987

Energy expenditure, energy balance, and composition of weight gain in low birth weight infants fed diets of different protein and energy content.

The effect of energy and protein intakes on energy expenditure, energy balance, and amount and relative rate of both protein and fat deposition in new tissue was investigated in 19 low birth weight infants whose mean protein and energy intakes, respectively, were 2.24 g/kg/d and 113 kcal/kg/d (formula A, n = 8), 3.6 g/kg/d and 115 kcal/kg/d (formula B, n = 5), and 3.5 g/kg/d and 149 kcal/kg/d (formula C, n = 6). The higher energy intake (formula C) but not the higher protein intake (formula B) resulted in greater energy expenditure. Both the higher protein (formula B vs formula A) and higher energy intakes (formula C vs formula B) resulted in greater weight gain secondary, in group B, to a greater absolute rate of protein deposition and, in group C, to a greater absolute rate of fat deposition. The relative composition of the new tissue deposited reflected the proportional intakes of protein and energy. The numerical value of the protein/fat ratio (g/g) of the new tissue deposited by infants fed formulas A and C, the protein contents of which were low relative to energy contents, were similar and significantly lower than the numerical value of the protein/fat ratio of the new tissue deposited by infants fed formula B, which had a higher protein content relative to energy content. These findings suggest that the composition of weight gain is related to both the absolute amounts and the proportions of dietary protein and energy; thus, both must be considered in formulation of nutritional regimens for LBW infants.

Body Weight↗
PubMed1987

Amino acid mixture designed to maintain normal plasma amino acid patterns in infants and children requiring parenteral nutrition.

A mixture of amino acids designed to maintain normal plasma amino acid concentrations of infants and children requiring parenteral nutrition was evaluated in 40 infants and children receiving only parenteral nutrients (2.39 +/- 0.26 g/kg/d of amino acids and 110.3 +/- 10.4 kcal/kg/d) for five to 21 days. The children ranged in weight from 2.0 to 12.6 kg (median weight, 3.83 kg; fifth to 95th percentile, 2.06 to 11.1 kg) and in age from 1 week to 43.6 months (median age, 2.7 months; fifth to 95th percentile, 0.2 to 25.3 months). Mean weight gain was 11.0 +/- 5.0 g/kg/d; mean nitrogen balance was 242 +/- 70 mg/kg/d. Plasma concentrations of all amino acids except tyrosine were within the normal range (ie, within the 95% confidence limits of the two-hour postprandial plasma concentrations observed in 30-day-old, healthy, normally growing, breast-fed, term infants) throughout the period of study. Mean prestudy and poststudy serum total protein, albumin, and transthyretin (prealbumin) concentrations were not significantly different. However, plasma transthyretin concentration increased in all children with low prestudy concentrations. Mean poststudy serum total bilirubin concentration of the total population was not different from the mean prestudy concentration. This was true also for the 31 children who received the parenteral amino acid mixture for more than ten days. In contrast to the expected 30% to 50% incidence of cholestasis, only one of these 31 experienced an unexplained increase in serum total bilirubin concentration during study, suggesting that normalizing plasma amino acid concentrations and/or providing taurine during parenteral nutrition may decrease the incidence of cholestasis associated with this therapy.

Amino Acids↗
PubMed1987

Protein quality in feeding low birth weight infants: a comparison of whey-predominant versus casein-predominant formulas.

Growth (delta weight, delta length, delta head circumference, and delta skinfold thickness), nitrogen retention, and chemical indices of metabolic tolerance (BUN concentration and acid-base status; plasma amino acid concentrations including free and bound cyst(e)ine; urinary excretion of sulfur amino acids) were determined serially in low birth weight infants (900 to 1,750 g) fed formulas differing only in protein quality. One contained unmodified bovine milk protein (a ratio of whey proteins to caseins of 18:82); the other contained modified bovine milk protein (a ratio of whey proteins to caseins of 60:40). Both provided protein and energy intakes, respectively, of approximately 3.4 g/kg/d and 120 kcal/kg/d. Neither weight gain nor the rate of increase in length, head circumference, and skinfold thickness differed between the two groups. Nitrogen retention of the two groups also did not differ. Although BUN concentration and blood acid-base status did not differ, there were differences in the plasma concentrations of some amino acids. Plasma tyrosine concentration was higher in infants fed the casein-predominant protein, and plasma threonine concentration was higher in infants fed the whey-predominant protein. Neither plasma-free nor bound cyst(e)ine concentration differed between the two groups, but the greater cyst(e)ine intake of the whey-predominant group resulted in greater cyst(e)ine retention; this was accompanied by greater urinary taurine excretion, a reflection of greater taurine stores.

Acid-Base Equilibrium↗
PubMed1986

Assessment of cortical and trabecular bone distribution in the beagle skeleton by neutron activation analysis.

The distribution of bone calcium between morphologically identifiable cortical and trabecular bone obtained by dissection and quantitated by neutron activation analysis (NAA) is described. The skeleton of a female beagle dog was dissected into approximately 400 pieces and assayed for 49Ca produced in the University of California, Irvine TRIGA reactor. For each of the skeletal sections, we give the initial weight of the alcohol-fixed tissue, which includes cortical bone, trabecular bone, marrow, and cartilage, and a final tissue weight after the marrow and trabecular bone have been dissected away; total section and cortical section calcium weights are reported. The level of detail is represented, for example, by the vertebrae, which were divided into three parts (body, spine, and transverse processes) and by the long bones, which were divided into 10-12 parts such that characterization of the epiphysis, metaphysis, and diaphysis was accomplished. The median percentage cortical calcium values for cervical, thoracic, and lumbar vertebrae were 82%, 56%, and 66%, respectively; however, variation within these groups and among individual vertebral sections was about a factor of 2. For long bones, the median percentage cortical calcium varied from 90-100% in the midshaft to below 50% in the proximal and distal sections. The final calculated cortical tissue-to-calcium mass ratio (TCR) varied from about 4.5 for midshafts of the long bones to about 9 for thoracic vertebral bodies and indicated that the mineral fraction of cortical bone is not constant throughout the skeleton. The ratio of cortical to trabecular calcium in the skeleton was 79.6:20.4.

Activation Analysis↗
PubMed1986

Effects of varying protein and energy intakes on growth and metabolic response in low birth weight infants.

Growth (weight, length, head circumference, and skinfold thickness), retention of major nutrients (nitrogen, sodium, potassium, chloride, calcium, and phosphorus), and chemical indices of protein adequacy (plasma albumin and transthyretin concentrations) and excess (blood urea nitrogen concentration and acid-base status; plasma amino acid concentrations) were determined serially from the time desired intake was tolerated until discharge weight (2200 gm) was reached in low birth weight infants (birth weight 900 to 1750 gm) fed one of three formulas, which provided protein and energy intakes, respectively, of 2.24 gm/kg/day and 115 kcal/kg/day (group 1), 3.6 gm/kg/day and 115 kcal/kg/day (group 2), and 3.5 gm/kg/day and 149 kcal/kg/day (group 3). Weight gain and rate of increase in length and head circumference were less in group 1 than in groups 2 and 3. Retention of most major nutrients also was less in group 1, as was blood urea nitrogen concentration, plasma albumin and transthyretin concentrations, and plasma concentrations of several amino acids. The rate of weight gain was not significantly greater in group 3 than in group 2, but the rate of increase in skinfold thickness was greater in this group. Neither nutrient retention nor metabolic indices differed between groups 2 and 3. These results suggest that a protein intake of 2.24 gm/kg/day is inadequate for the type of LBW infants studied, that the higher protein intakes are well tolerated, and that an energy intake of 149 vs 115 kcal/kg/day does not enhance utilization of the higher protein intakes studied.

Acid-Base Equilibrium↗
PubMed1986

Lack of relationship in humans of the parameters of body cholesterol metabolism with plasma levels of subfractions of HDL or LDL, or with apoE isoform phenotype.

The factors involved in regulating parameters of whole body cholesterol metabolism in humans have been explored in a series of investigations. Several physiological variables have been identified (weight, excess weight, plasma cholesterol, and age) that can predict 53-76% of the variation in production rate (PR) and in the sizes of the rapidly exchanging pool of body cholesterol (M1) and of the minimum estimates of the slowly exchanging pool of body cholesterol (M3min) and of total body cholesterol (Mtotmin). Surprisingly, measurements of the plasma levels of HDL cholesterol and of the major HDL apolipoproteins (apoA-I, A-II, and E) did not provide additional information useful in predicting parameters of whole body cholesterol metabolism. A study was therefore conducted to investigate possible relationships of the plasma levels of subfractions of lipoproteins, determined by analytic ultracentrifugation, and of apoprotein E phenotype, with the parameters of whole body cholesterol metabolism. Ultracentrifugal analysis of plasma lipoprotein subfractions was performed at the Donner Laboratory in 49 subjects; all of these subjects were currently undergoing whole body cholesterol turnover studies or had previously had such studies and were in a similar metabolic state as judged by plasma lipid and lipoprotein values. Apoprotein E phenotyping was carried out in 71 subjects. Differences in model parameters were sought among subjects with various apoprotein E phenotypes. Ultracentrifugal LDL subfractions Sof 0-2 (the region of LPa), Sof 0-7 (smaller LDL), Sof 7-12 (larger LDL), Sof 12-20 (IDL), and ultracentrifugal HDL subfractions Fo1.20 0-1.5 (smaller HDL3), Fo1.20 2-9 (larger HDL3 plus HDL2), and Fo1.20 5-9 (larger HDL2 or HDL2b) were examined for correlations with each other and with parameters of whole body cholesterol metabolism.

Adolescent↗