Biomedical subjects

A D Robertson

Publications and source records attributed to A D Robertson.

At least 91 records · Page 5Linked to original sources

PubMed1988

Effect of continued oral feeding on clinical and nutritional outcomes of acute diarrhea in children.

One hundred twenty-eight nonmalnourished male patients between 3 and 36 months of age were randomly assigned to receive one of four lactose-free dietary treatments to determine the effect of dietary therapy on the severity and nutritional outcome of diarrheal illness. Group 1 received a formula diet composed of casein, sucrose, dextrin with maltose (Dextri-Maltose), and vegetable oil to provide 110 kcal/kg body weight/d (CSO-110). Group 2 received CSO to provide 55 kcal/kg/d (CSO-55) for 2 days and then CSO-110. Group 3 received only oral glucose-electrolyte solution (GES) for 2 days, CSO-55 for the next 2 days, and then CSO-110. Group 4 received the same diets as Group 3 except that only intravenous GES was used for the first 2 days. The GES maintenance solutions provided 24 to 30 kcal/kg/d. Therapeutic success rates were similar among dietary groups, ranging from 90% to 97%. Fecal excretion was initially lower in group 4 (P less than 0.05) but was similar initially among groups treated orally and among all four groups beginning on day 3. Net apparent absorption of nitrogen, fat, carbohydrate, and total energy; retention of nitrogen; and increments in body weight, arm circumference, and skin-fold thickness were positively related to the amounts of dietary energy consumed. Thus continued oral feeding with the CSO diets during the early phase of therapy yielded improved nutritional results.

Absorption↗

PubMed1988

Current approach to treatment of primary pulmonary hypertension.

Based upon our experience with a cohort of 46 patients referred to the UCHSC from April, 1980 to April, 1987 for evaluation and treatment of PPH, we currently assess acute pulmonary vasoreactivity as defined by the patient's response to intravenous PGI2 during the initial diagnostic catheterization. A 3 to 5 day trial of high dose oral diltiazem treatment (720 mg/day maximum) is given while monitoring the patient in the clinical research center to detect significant side effects including arrhythmias, orthostatic systemic hypotension, arterial desaturation, and worsened right ventricular dysfunction. We believe it is necessary to recatheterize each patient to establish the efficacy of calcium antagonist treatment prior to discharge. Those patients who are responsive to diltiazem are discharged and followed in our pulmonary hypertension clinic. Since an occasional patient will deteriorate after several weeks of therapy, repeat right heart catheterization after 8 weeks of treatment is used to determine which patients should be continued on diltiazem for chronic therapy. Approximately 30 percent of our patients with PPH have been improved on diltiazem treatment. Most patients who have a good response to treatment after eight weeks continue to benefit from long-term treatment. It appears that the response to an acute infusion of PGI2 is useful in safely identifying those PPH patients who are likely to benefit from vasodilator therapy. Debilitated patients who are unresponsive to PGI2 and vasodilator therapy are considered potential candidates for cardiopulmonary transplantation.

Administration, Oral↗

PubMed1988

Transbilayer movement of cholesterol in the human erythrocyte membrane.

The rate of transbilayer movement of cholesterol was measured in intact human erythrocytes. Suspended erythrocytes were incubated briefly with [3H]cholesterol in ethanol at 4 degrees C, or with liposomes containing [3H]cholesterol over 6 hr at 4 degrees C to incorporate the tracer into the outer leaflet of erythrocyte plasma membranes. The erythrocytes were then incubated at 37 degrees C to allow diffusion of cholesterol across the membrane bilayer. Cells were treated briefly with cholesterol oxidase to convert a portion of the outer leaflet cholesterol to cholestenone, and the specific radioactivity of cholestenone was determined over the time of tracer equilibration. The decrease in specific radioactivity of cholestenone reflected transbilayer movement of [3H]cholesterol. The transbilayer movement of cholesterol had a mean half-time of 50 min at 37 degrees C in cells labeled with [3H]cholesterol in ethanol, and 130 min at 37 degrees C in cells labeled with [3H]cholesterol exchanged from liposomes. The cells were shown, by the absence of hemolysis, to remain intact throughout the assay. The presence of 1 mM Mg2+ in the assay buffer was essential to prevent hemolysis of cells treated with cholesterol oxidase perturbed the cells, resulting in an accelerated rate of apparent transbilayer movement. Our data are also consistent with an asymmetric distribution of cholesterol in erythrocyte membranes, with the majority of cholesterol in the inner leaflet.

Biological Transport↗

PubMed1987

Biphasic responses, quantal signals and cellular behaviour.

It is commonplace to think of thresholds in biological systems. Biphasic responses, with both thresholds and upper limits, or lintels, are also surprisingly common. In this paper we show that they are found in many systems in which an aspect of cellular behaviour is controlled by chemical signals. In some cases the biphasic response can lead to the partitioning of a tissue into regions expressing different behaviours and, therefore, in principle able to take different developmental and evolutionary paths within the same organism. Several other features are common; these include brief, all-or-nothing responses and the expression of different behaviours evoked by a signal of a single chemical species in one or more cell types, but over different concentration ranges. Such behaviour is illustrated very clearly by the differentiation of cells in the mammalian immune system as well as by developing slime mould cells, so the underlying principle is widespread. We suggest that the interaction of unitary behaviours with chemical signals showing such non-linear concentration dependences will account for the complexity of development.

Animals↗

PubMed1986

Bicarbonate versus citrate in oral rehydration therapy in infants with watery diarrhea: a controlled clinical trial.

In a double-blind, randomized trial, we compared the efficacy of bicarbonate-containing oral rehydration solution vs citrate-containing solution in the treatment of infantile diarrheal dehydration and acidosis. Ninety-seven infants 3 to 24 months of age were entered in the study; 49 received bicarbonate-containing solution and 48 citrate-containing solution. The two groups were similar in all respects at the beginning of the study. Oral rehydration was successful (i.e., no intravenously administered fluids were required) in 85% of study patients; the success rate was similar in both treatment groups. Serum total CO2 concentration increased in a similar fashion in both groups, reaching near normal values at 48 hours after admission. We conclude that sodium citrate can be substituted for sodium bicarbonate in the formulation of the orally administered rehydration solution recommended by the World Health Organization for treatment of diarrheal dehydration in infants.

Bicarbonates↗

PubMed1986

Lactational capacity of marginally nourished mothers: relationships between maternal nutritional status and quantity and proximate composition of milk.

Longitudinal studies of the nutritional status of 60 lactating Bangladeshi mothers from an underprivileged, periurban community and of the quantity and composition of their milk were completed to determine the relationships between maternal nutritional status and lactational capacity. Daily milk production was estimated by 24-hour test-weighing; the nitrogen, fat, lactose, and total energy concentrations of extracted milk samples were analyzed at various stages of lactation to estimate total milk nutrient production. Although the mothers were poorly nourished compared with international reference populations, their lactational capacity was not severely impaired. Average milk production peaked at 750 g/d when the infants were between 5 and 7 months of age. Nitrogen and fat concentrations declined with (log) infant age; lactose concentration increased with (log) infant age (P less than .001). Average concentrations of milk nutrients when the infants were 3 months of age were: nitrogen, 0.161 g/dL; fat, 2.804 g/dL; lactose, 7.92 g/dL; energy, 61.0 kcal/dL. Fat and energy concentrations were significantly greater, and fat and energy amounts tended to be greater, for mothers with larger triceps skinfold thickness or arm circumference. Changes in nutritional status within individual women were also significantly related to the amount and composition of their milk: within-woman increases in triceps skinfold thickness were associated with increases in fat and energy concentrations (P less than .01) and within-woman increases in body weight were associated with increases in the amounts of milk and all major nutrients (P less than .01). Milk production declined significantly during certain months of the year, just before the major harvest period. The findings suggest that, despite their remarkably good lactational capacity, the mothers' milk production was limited to some extent by their nutritional status and may, therefore, be further increased with nutritional improvement.

Adolescent↗

PubMed1986

Lactational capacity of marginally nourished mothers: infants' milk nutrient consumption and patterns of growth.

The consumption of human milk by 58 Bangladeshi infants of marginally nourished mothers was measured during longitudinal studies. Daily milk consumption, as estimated by test weighing, and intakes of energy and protein, as calculated from the measured concentrations of macronutrients in the milk, were related to infant body weight, to internationally recommended intakes of these nutrients, and to the infants' patterns of physical growth. Each of the milk variables, when related to infant body weight, declined significantly with increasing (log) infant age (P less than .001). The average consumption of energy and protein was less than current recommendations at all ages. Nevertheless, the average growth of the Bangladeshi infants approximated the fifth centile of the US National Center for Health Statistics during the first 4 months of life. By the fourth month, however, the weight increments of more than half the infants (79%) were less than the reference data. The intakes of energy and protein by individual infants less than 90 days of age were related to their patterns of growth. There were significant positive relationships between the change in Z score weight-for-age and weight-for-length and the consumption of breast milk energy (kilocalories per kilogram of body weight per day) and protein (grams per kilogram per day). Consumptions of 86.5 kcal/kg/d and protein 1.48 g/kg/d were associated with a nonchanging Z score weight-for-age. Thus, intake of these amounts of nutrients permitted weight gain comparable to the reference population but did not permit recovery from the existing relative weight deficits.

Bangladesh↗

PubMed1985

Effects of season and illness on the dietary intake of weanlings during longitudinal studies in rural Bangladesh.

Longitudinal, quantitative studies of the dietary intake of 70 weanlings between five and 30 months of age from two Bangladeshi villages have been analyzed to determine the effects of season and illness on dietary intake. During 1014 days of observation, all foods consumed by the children were weighed by a field worker present in the home; 24-hour breast milk intake was estimated from 12-hour test weighings. Inter-individual differences explained 29% to 50% of the variance in consumption of selected nutrients and foods during 632 studies conducted when children were free from diarrhea and fever. Multiple linear regressions controlling for inter-individual differences indicated that 60-day seasonal periods explained a significant proportion of the variation in intake. Average energy consumption (kcal/kg/d) was approximately one-third greater during the post-harvest periods than during the pre-harvest monsoon period. Breast milk intake varied similarly even after controlling for age-related decreases. Consumption of rice and wheat, the major non-breast milk sources of energy and protein, had distinct seasonal patterns, thus limiting the overall seasonal variability in cereal intake. Older children, particularly boys, benefited more from the post-harvest relative abundance of food. The intake of most nutrients was significantly depressed by approximately 10% during febrile illnesses. Minor decreases in intake with other illnesses were not statistically significant.

Age Factors↗

PubMed1983

Diagnosis of GM1 gangliosidosis based on detection of urinary oligosaccharides with high performance liquid chromatography.

An improved, rapid, and sensitive method for the biochemical diagnosis of GM1 gangliosidosis based on the detection and quantification of urinary galactosyl-oligosaccharides with high performance liquid chromatography was developed. The oligosaccharides, in 50-100 microliters of urine, were converted to radioactively labeled oligosaccharide-alditols with NaB3H4 and fractionated on commercial silica-amine bonded, high performance liquid chromatography columns. Delineation between infantile, juvenile, and adult onset subtypes of GM1 gangliosidosis was possible by analysis of the levels of the excreted oligosaccharides and their characteristic elution profile. Infantile and juvenile patients contain identical numbers of oligosaccharide fractions (13 resolved components) but can be distinguished by 3-10-fold lower levels of oligosaccharides in juvenile patients and, in some cases by a disproportionately lower concentration of high molecular weight compounds. Adult onset patients were distinguished by substantially lower concentrations of urinary oligosaccharides, 130-180-fold below those in infantile patients, and the apparent absence of high molecular weight oligosaccharides.

Adult↗

PubMed1983

Prenatal diagnosis of GM1 gangliosidosis by detection of galactosyl-oligosaccharides in amniotic fluid with high-performance liquid chromatography.

Prenatal diagnosis of infantile GM1 gangliosidosis was accomplished by analyzing the galactosyl-oligosaccharides accumulating in amniotic fluid with high-performance liquid chromatography (HPLC) at 14 weeks gestation. The pattern of amniotic oligosaccharides was nearly identical with that in neonatal urine in GM1 gangliosidosis but the concentrations were about one-fiftieth of that in urine, necessitating a highly sensitive assay.

Amniotic Fluid↗

PubMed1982

Clinical and field studies of human lactation: methodological considerations.

A variety of studies has been completed to assess selected methods that are presently being used or might potentially be used to evaluate lactation performance. During 64 test-weighings of infants before and after the consumption of a known amount of milk, the mean +/- SD "recovery" of milk ingestion was 94.9 +/- 13.2%. The weight of milk extracted by a mechanical pump was approximately 7% greater than the amount measured during test-weighings of infant of the same women within periods of 1 wk. To evaluate the possibility of performing abbreviated studies in field settings, the proportion of 24-h milk consumption received during 12 daytime hours was measured by test-weighings. Daytime consumption ranged from 46 to 58% of 24-h consumption (mean +/- SD = 52 +/- 3%). Attempts to predict the amount of milk consumption during 341 daytime studies from the age of infants and their frequency and duration of feedings met with limited success. Although each independent variable was significantly correlated with the amount consumed (multiple r = 0.69, p less than 0.001), the SE of the estimate (Sy.x) was relatively large. The effects of time of day and side of extraction on the volume and composition of extracted milk were determined during 24-h studies of seven women. There were significant changes in the concentration of fat (p less than 0.001) and nitrogen (p = 0.003) during the day and significant differences in the concentrations of fat (p = 0.04) and lactose (p = 0.04) and in the volume (p less than 0.001) of milk produced by each breast. The importance of these findings for the planning and interpretation of studies of human lactation is discussed.

Adolescent↗

PubMed1982

Arm muscle indicators and creatinine excretion in children.

The ability of anthropometric measurements, including arm muscle area calculated from arm circumference and triceps skinfold thickness, to estimate creatinine excretion as an index of muscle mass was tested in 14 fully active children, 2 to 6 yr of age in a residential care facility. The children were placed on a meat and fish-free diet for 36 to 48 h before the determination of mean creatinine excretion during three 24-h urinary collections. Results indicated highly significant correlations between mean creatinine excretion and height (r = 0.71), weight (r = 0.69), and arm circumference (r = 0.63). However, arm muscle area had the highest correlation with creatinine excretion (r = 0.86) of any anthropometric variable used. Step-wise multiple-regression analysis indicated that including height or weight with arm muscle area did not significantly improve the estimation of creatinine excretion, but that weight for height added significantly to improve the estimation of creatinine excretion, but that arm muscle area can provide a useful index of body muscle as reflected in urinary creatinine excretion in young children.

Arm↗

PubMed1982