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Biomedical subjects

W Oh

Publications and source records attributed to W Oh.

At least 199 records · Page 11Linked to original sources
PubMed1983

Renal response in low-birth-weight neonates. Results of prolonged intake of two different amounts of fluid and sodium.

Changes in renal function and extracellular fluid volume during the first ten days of life were studied in two groups of low-birth-weight neonates receiving different fluid and sodium intakes from the third to the tenth day. Group 1 neonates received less fluid and sodium and fewer calories than group 2 neonates. Renal function and inulin space were measured before (day 2) and after (day 8) the neonates received the different fluid and sodium managements. Group 2 neonates (on the eight day) had less weight loss, lower plasma sodium and osmolal concentrations, and a similar inulin space per kilogram of body weight as on day 2. Group 1 neonates had more weight loss and a smaller inulin space on day 8 compared with day 2. Low-birth-weight neonates receiving high fluid and sodium loads from days 2 through 8 did not have a contraction of extracellular fluid volume as did those receiving lower fluid and sodium intakes during this period; as a result, the former group had a dilutional decrease in the plasma sodium level and osmolality.

Extracellular Space↗
PubMed1983

Impermeability of the rat placenta to insulin during organogenesis.

The cause of the embryopathy associated with diabetes mellitus is uncertain. To examine whether exogenously administered insulin may be teratogenic, tracer amounts of radiolabelled insulin were infused for two hours during organogenesis (day 12 1/2 of gestation) into three groups of pregnant rats: control (n = 8), diabetic (n = 5), and hyperinsulinemic (n = 4). For maternal plasma, no differences were found among the three study groups in the percentage of the protein-precipitable (insulin-containing) radioactivity. Tissue radioactivities were expressed relative to the two-hour maternal plasma sample. Maternal kidney samples had the highest total and protein precipitable counts followed in descending order by the maternal plasma, maternal liver, placenta, and embryo. No differences in radioactivities were noted among the three study groups for specific tissues studied. Protein-precipitable radioactivities in the embryo were more than 100-fold less than the maternal plasma values. In 11 of the 17 litters, the acid-insoluble fractions of the embryos were not distinguishable from background counts, and none of the remaining six were greater than twice background. These studies demonstrate that during the period of organogenesis, the rat embryo is protected from maternal insulin by the placenta, and hence, maternal insulin is an unlikely teratogen.

Animals↗
PubMed1983

Effect of increased substrate availability on fatty acid synthesis in the growth retarded fetus.

The purpose of this study was to test the hypothesis that increased substrate (glucose) availability will enhance fatty acid synthesis in the growth retarded rat fetus. At 17 days of gestation, 19 time-dated pregnant rats had one uterine artery ligated, leading to growth retardation (IUGR) in the fetuses located on the uterine horn supplied by the ligated artery. The uterine artery of the opposite uterine horn was left untouched, resulting in appropriately grown fetuses, which served as controls. At 21 days of gestation the animals were infused with either 20% dextrose or 0.9% saline via a maternal jugular vein catheter for 4 hr. Fetal organ fatty acid synthesis was measured by maternal 3H2O injection. In the growth retarded saline infused fetus, specific activity for 3H (representing rate of fatty acid synthesis) was significantly lower in fetal liver, lung and carcass. Dextrose infusion resulted in increased fatty acid synthesis in both control and IUGR fetuses in all tissues cited above. The specific activity in glucose infused IUGR fetal organs equalled that of saline infused control fetuses. The data indicate that maternal glucose infusion resulted in an increased rate of fatty acid synthesis, in IUGR fetuses; consequently, the deficit in fatty acid synthesis in the IUGR fetus (compared to appropriately grown control fetuses) was abolished.

Animals↗
PubMed1983

Glucocorticoid accelerates renal functional maturation in fetal lambs.

Renal function was measured in seven premature lambs delivered spontaneously after a fetal injection of betamethasone, four near term lambs delivered via cesarean section after a fetal injection of a placebo and in ten spontaneously delivered full term lambs. Glomerular filtration rates were significantly higher in the premature betamethasone treated than in the near term placebo treated and the full term lambs. Fractional sodium excretions were significantly lower in the betamethasone treated preterm than the placebo treated near term lambs. This suggests that glucocorticoid accelerates renal glomerular and possibly tubular maturation. As in the lung, fetal administration of glucocorticoid stimulates functional maturation of the kidney.

Animals↗
PubMed1983

Effects of maternal ritodrine administration on neonatal renal function.

Because of its effects on the cardiovascular and renin-angiotensin systems and on fluid and electrolyte homeostasis, maternal administration of ritodrine to inhibit preterm labor may cause significant alterations in renal function in the newborn infant. We determined inulin clearance, plasma renin activity, urinary arginine vasopressin excretion, and serum and urine electrolyte concentrations and osmolalities at 12 to 36 hours of life and at 6 days of life in 15 infants whose mothers had received ritodrine and in 15 infants whose mothers did not (control infants). At the time of each study, plasma ritodrine concentrations were obtained in the infants whose mothers received ritodrine. The infants whose mothers had received ritodrine had significantly lower inulin clearances and higher plasma renin activity and urinary arginine vasopressin excretion on day 1 but not on day 6. Gestational age was inversely correlated with plasma ritodrine concentration, plasma renin activity, and urinary arginine vasopressin excretion. There were no overt clinical signs of renal failure in any of the infants, and no differences in serum and urine electrolyte values, osmolality, fractional sodium excretion, or urine flow rate were observed between the groups.

Arginine Vasopressin↗
PubMed1983

Growth and development in preterm infants small for gestational age.

The growth pattern and neurologic and developmental performance of 21 preterm infants small for gestational age and 20 preterm infants appropriate for gestational age (birth weight less than 1500 gm) were prospectively studied. The two groups had comparable birth weight, sex, perinatal morbidities, and socioeconomic status. All infants with congenital anomalies or genetic defects were excluded. Nineteen of 21 SGA (90%) and 16 of 20 AGA (80%) infants born in 1975 or 1976 were evaluated in our follow-up program until 5 years of age. At 1 year of age, the weights and lengths of the SGA infants were comparable to those of their AGA counterparts; AGA infants were significantly heavier, however, at 2, 3, 4, and 5 years of age. In addition, AGA infants were significantly taller at 2, 3, and 5 years. Neurologic evaluation of 5 years showed a comparable rate of major abnormalities between the SGA (15%) and AGA (12%) children. Minor neurologic abnormalities were present in 26% of SGA and 12% of AGA children. Linear-regression analysis demonstrated a positive relationship between socioeconomic status and developmental outcome for both SGA and AGA children at 5 years of age. Although SGA infants scored significantly lower in developmental performance at 9 months through 3 years of age, at 4 to 5 years of age this difference was no longer observed. These observations indicate the importance of long-term follow-up.

Body Height↗
PubMed1983

Enhanced fatty acid synthesis in hyperinsulinemic rat fetuses.

The relationship between insulin-induced macrosomia and fetal fatty acid synthesis in nine pregnant rats was evaluated using the tritiated water technique. On days 19 and 21 of gestation, alternate fetuses were injected with equal volumes of either saline or insulin (5 units). Fetal hyperinsulinemia resulted in a significant increase in fetal weight and selected organ weights (liver, lung and carcass). Significant increases in fatty acid synthesis in fetal liver and carcass were observed on day 22 of gestation. In liver tissue, increased fatty acid synthesis occurred as evidenced by increased tritium incorporation into fatty acids in insulin-injected fetuses, 690 +/- 124 cpm/liver, compared to controls, 400 +/- 92 cpm/liver (P less than 0.001); higher fatty acid content, 16.0 +/- 1.3 mumol/liver in hyperinsulinemic fetuses, compared to 12.3 +/- 1.0 mumol/liver in controls (P less than 0.005); and a higher fatty acid specific activity, (expressed as tritium counts per minute per micromole fatty acid) 44.5 +/- 8.6 cpm/mumol fatty acid, compared to control levels of 33.0 +/- 7.5 (P less than 0.005). Analysis of carcass revealed higher tritium incorporation into fatty acids in insulin-injected fetuses, as compared to controls, 2136 +/- 172 versus 1139 +/- 122 cpm/carcass (P less than 0.001); higher fatty acid content, 68.1 +/- 7.3 versus 59.4 +/- 6.4 mumol/carcass (P less than 0.05); and fatty acid specific activity, 34.5 +/- 4.8 versus 21.9 +/- 4.4 cpm/mumol (P less than 0.001), respectively. There were no differences in the incorporation of tritium into fatty acids or fatty acid content in the lung, brain and placenta in the insulin-treated fetus as compared to control littermates. The data indicate that insulin is a lipogenic hormone for the fetus and that this model can be used as a means of studying effects of insulin on fat metabolism in fetal life.

Animals↗
PubMed1983

Effects of intravenously administered safflower oil emulsion on respiratory gas exchange of low-birth-weight infants.

Safflower oil emulsion (Liposyn 10%) was infused intravenously to supplement energy intake in five low-birth-weight infants. Respiratory gas exchange was measured before and after the addition of fat emulsion in doses of 1-2 g of fat/kg/day to an intravenous feeding regimen of dextrose and amino acids. The oxygen consumption and carbon dioxide production rates were greater during fat infusion in all infants, but the mean respiratory quotient was not different. The increase in energy intake provided by the fat emulsion exceeded the increase in energy expenditure, allowing more energy to be stored for growth.

Emulsions↗
PubMed1983

Reserve albumin and bilirubin toxicity index in infant serum.

Reserve albumin concentration (the concentration of albumin available for binding of unconjugated bilirubin) was determined in 95 sera from 76 subjects by dialysis with 14C-monoacetyl diamino diphenyl sulfone (MADDS). An index, I of bilirubin toxicity in the plasma was calculated for each subject, based on the bilirubin and reserve albumin concentrations, the affinity of bilirubin for serum albumin, and the pH-dependent solubility of bilirubin in the plasma. The values of reserve albumin and of I varied significantly with gestational age, clinical condition (whether sick or well), and serum bilirubin level. The value of reserve albumin was decreased and I was increased in association with clinical factors (e.g., hyperbilirubinemia, hypoxia, acidosis, or sepsis) recognized as increasing the risk for bilirubin encephalopathy. The lowest values of reserve albumin and the highest values of I were found in the least mature and sickest infants.

Adult↗
PubMed1983

Water requirement of premature newborn infants.

Two groups of studies related to the water requirement of premature infants are reviewed. The first examined the effects of several environmental factors on insensible water loss (IWL) and oxygen consumption of 20 low-birth-weight infants. Incubator air temperature above the neutral zone increased IWL, as did the use of a radiant heat source instead of a conventional incubator. A plastic heat shield slightly reduced IWL of infants in incubators. The second group of studies examined the effects of excess water intake in premature infants. 170 infants were randomly assigned to receive "low" (average estimated requirement for birth weight and age) or "high" (excess) volume water intake. The high-volume group became dehydrated less often but had a greater incidence of patient ductus arteriosus and necrotizing enterocolitis.

Dehydration↗
PubMed1983

Gastrointestinal blood flow and oxygen consumption in awake newborn piglets: effect of feeding.

Regional and total gastrointestinal (GI) blood flow, O2 delivery, and whole-gut O2 extraction and O2 consumption were measured before and 30, 60, and 120 min after feeding in nonanesthetized, awake 2-day-old piglets. Cardiac output and blood flow to kidneys, heart, brain, and liver were also determined. Blood flow was measured using the radiolabeled microsphere technique. In the preprandial condition, total GI blood flow was 106 +/- 9 ml X min-1 X 100 g-1, while O2 extraction was 17.2 +/- 0.9% and O2 consumption was 1.99 +/- 0.19 ml O2 X min-1 X 100 g-1. Thirty minutes after slow gavage feeding with 30 ml/kg artificial pig milk, O2 delivery to the GI tract and O2 extraction rose significantly (P less than 0.05) by 35 +/- 2 and 33 +/- 2%, respectively. The increase in O2 delivery was effected by a significant increase in GI blood flow, which was localized to the mucosal-submucosal layer of the small intestine. O2 uptake by the GI tract increased 72 +/- 4% 30 min after feeding. Cardiac output and blood flow to non-GI organs did not change significantly with feeding, whereas arterial hepatic blood flow decreased significantly 60 and 120 min after feeding. The piglet GI tract thus meets the oxidative demands of digestion and absorption by increasing local blood flow and tissue O2 extraction.

Animals↗
PubMed1983

Echocardiographic effects of high and low volumes of maintenance fluid administration in low-birth-weight infants.

Serial M-mode echocardiograms were performed during days 3-20 of life in 73 low-birth-weight infants randomized on day 3 of life to 'high' (n = 40) and 'low' (n = 33) fluid regimens designed to give significantly different maintenance fluid intakes (172 +/- 25 and 121 +/- 13 ml/kg/day, mean +/- SD, respectively, p less than 0.001). The groups were comparable with respect to birth weight, gestational age, incidence of respiratory distress syndrome and mean number of serial echocardiograms performed per infant (9 and 9), respectively. Calorie and electrolyte intake were not controlled in the study design. Cumulative echocardiographic data were compared by unpaired t test. Left ventricular end diastolic diameter, right ventricular end diastolic diameter, septal excursion, left ventricular posterior wall excursion and left atrial to aortic root ratio were slightly but statistically significantly larger in the 'high' fluid group. Comparison of regression coefficients showed that left ventricular end-diastolic diameter tended to rise with postnatal age in the 'high' group and fall with postnatal age in the 'low' group. Left atrial to aortic root ratio tended to fall with postnatal age in the 'low' group relative to the 'high' group. These differences in echocardiographic measurements may reflect adaptation of the circulation to a degree of chronic volume overload in low-birth-weight infants.

Aging↗
PubMed1983

Bilirubin-displacing effect of furosemide and sulfisoxazole. An in vitro and in vivo study in neonatal serum.

Sulfisoxazole and furosemide, 0.1-1.0 mM, both decreased reserve albumin concentration for bilirubin binding in pooled cord serum as estimated by rate of dialysis of 14C-monoacetyl-diamino-diphenylsulfone (MADDS) in undiluted serum at 37 degrees C. Peroxidase oxidation at a bilirubin:albumin ratio of 0.5 also showed that both drugs were capable of displacing bilirubin in vitro when added in molar excess of the albumin present. However, when aliquots of the same treated sera which had been used undiluted in the MADDS assay were diluted 40-fold and titrated with bilirubin and peroxidase, no drug-related increase in free bilirubin or decrease in reserve albumin could be shown. In vivo administration of 1 mg/kg furosemide showed no change in total bilirubin or reserve albumin by the MADDS technique in 8 infants. Estimation of the peak plasma level theoretically achievable with 1 mg/kg of furosemide suggests that peak plasma levels achieved with that dose are probably not high enough to produce significant reduction of reserve albumin, in agreement with the in vivo findings. In testing neonatal serum for bilirubin displacement by drugs, the choice of method, drug concentration, and dilution of the sample may influence the interpretation of results.

Bilirubin↗
PubMed1983

Effect of aminophylline on brain blood flow in the newborn piglet.

The effect of 6 mg/kg of aminophylline on brain blood flow was examined in newborn piglets. Arterial plasma aminophylline concentration averaged 7 mg/l. Total brain, regional brain (cerebrum, cerebellum and stem) and eye blood flow as well as the total brain oxygen consumption were not altered by aminophylline treatment. Choroid plexus blood flow was five times higher than the total brain blood flow in these newborn piglets. In contrast to brain blood flow, choroid plexus blood flow decreased significantly following aminophylline administration.

Aminophylline↗
PubMed1983

Persistent glucose production during glucose infusion in the neonate.

In adults, glucose infusion results in a decreased glucose production rate (GPR) as a mechanism for maintaining euglycemia. To document the development of glucose homeostasis, we derived the GPR in 23 preterm appropriate for gestational age infants, 14 term appropriate for gestational age infants, and in 6 adults. After a 3-h fast, the average plasma glucose and insulin concentration was measured and the GPR was derived. During glucose infusion (5.6 +/- 0.3 mg X kg-1 min-1), compared with saline controls, the preterms had a rise in plasma glucose and plasma insulin, and the GPR was 1.4 mg X kg-1 min-1 (range, 0-4.4) vs. 3.0 mg X kg-1 min-1 (range, 1.8-4.1) (saline controls). In the term infants, only the plasma insulin concentration was elevated when the glucose infused (5.7 +/- 0.3 mg X kg-1 min-1) infants were compared with the saline controls and GPR was 0.4 X kg-1 min-1 (range, 0-2.6) vs. 3.4 mg X kg-1 min-1 (range, 2.8-5.7) (saline controls). In comparison to saline infused adults, glucose infusion (3.2 +/- 0.1 mg X kg-1 min-1) resulted in a significant rise in plasma glucose and in plasma insulin; and the GPR was reduced to 0.1 mg X kg-1 min-1 (range, 0-0.3) from 2.0 mg X kg-1 min-1 (range, 1.5-2.4). 5 of 13 preterms and 2 of 7 term infants had persistent GPR during glucose infusion; in contrast, the GPR in all adults was unmeasurable. There was no correlation between the plasma glucose concentration and the GPR in the newborn or in the adult. Both newborns and adults did have a correlation between plasma insulin concentration and the GPR; however, there was considerable variability in the neonate. We conclude that there are significant developmental differences in neonatal glucose homeostasis and that insulin is important in neonatal hormonal control of glucose production.

Adult↗
PubMed1983

Post-hepatic insulin secretion in the fetal lamb.

Post-hepatic insulin secretion was measured in six chronically catheterized fetal lambs (fetal weight 2.8 +/- 0.3 kg, mean +/- S.E.M.) and the results were compared with those obtained in nine prematurely delivered newborn lambs (birth weight 3.1 +/- 0.3 kg and postnatal age 1.3 +/- 0.2 days). The fetal and neonatal lambs received either a 0.45% saline or a glucose infusion respectively, which resulted in a 2-fold increase in the plasma glucose concentration. [131I]insulin was infused for 110 min to determine the rate of insulin secretion during a steady state of plasma glucose concentration. Post-hepatic insulin secretion and the metabolic clearance rate were calculated. With the 2-fold rise in plasma glucose concentration, the post-hepatic insulin secretion rate increased significantly in the newborn lamb and in three out of four fetuses. The plasma insulin concentration increased significantly in the fetus (11 +/- 4.0 to 35 +/- 8 microU/ml, P less than 0.05) during glucose stimulation as a result of decreased metabolic clearance rate of insulin (10.6 +/- 1.9 to 6.3 +/- 1.8 ml . kg-1 . min-1) and an increase in post-hepatic insulin secretion rate. In spite of an increase in post-hepatic insulin secretion rate, the increase in plasma insulin concentration in the newborn lamb was not significant because of large variation in the values obtained. The data suggest that pancreatic beta-cells in the newborn and in the fetal lamb are equally responsive to a 2-fold increase in plasma glucose concentration.

Animals↗