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Biomedical subjects

W Oh

Publications and source records attributed to W Oh.

At least 289 records · Page 16Linked to original sources
PubMed1977

Renal functions of low birth weight infants during the first two months of life.

A postnatal contraction of extracellular fluid occurs in low birth weight infants. Patterns of postnatal renal maturation were assessed with the assumption that changes in body composition were mediated in part by the developing kidney. Twenty-two appropriate for gestational age, low birth weight infants (birth weight mean = 1380 g, gestational age mean 31 weeks) were studied between 12 hr and 61 days of age to evaluate simultaneously glomerular and tubular functional maturation. Since most low birth weight infants have respiratory morbidities (respiratory distress followed by chronic lung disease), the infants were grouped into: group I (13 infants), transient or absent respiratory morbidities; and group II (9 infants), persistent and severe respiratory morbidites. Sodium excretion decreased with postnatal age in both groups. Sodium intake did not vary with postnatal age. The percentage of fractional sodium excretion was inversely related to postnatal age. Creatinine clearance correlated directly with postnatal age in both groups. Increased sodium excretion and percentage of fractional sodium excretion in the first 10 days of life may reflect extracellular fluid solute losses through the kidney. The premature kidney matured in a balanced fashion and persistent respiratory morbidities did not alter this pattern.

Body Composition↗
PubMed1977

The lack of effects of phototherapy on neonatal oxygen dissociation curves and hemoglobin concentration in vivo.

Phototherapy has been shown to cause hemolysis of fetal red cells and a shift to the right in the neonatal oxygen dissociation curve (deltaP50) in vitro. To determine if these parameters act similarly in vivo, we have studied 16 icteric infants before and after phototherapy and compared them with eight control infants studied at birth and at 3 days of age, measuring the change in P50, 2,3-diphosphoglycerate (2,3-DPG), serum bilirubin, the percent of bilirubin/albumin saturation, and the hemoglobin concentration in the two groups. Following phototherapy, in the icteric infants there was a shift to the right in the O2 dissociation curve of + 1.7 mm Hg, a rise in 2,3-DPG of 2.26 micronmol/gm Hb, a fall in serum bilirubin of 4.3 mg/100 ml, a decrease in percent bilirubin/albumin saturation of 12.4%, and a drop in hemoglobin of 1.1 gm/100 ml. The control group showed a deltaP50 of + 2.0 mm Hg, a rise in 2,3-DPG of 3.67 micronmol/gm Hb, an increase in serum bilirubin of 3.2 mg/100 ml, an increase in percent bilirubin/albumin saturation of 9.3%, and a fall in hemoglobin of 0.3 gm/100 ml. Significant differences between the groups were seen only in the changes in bilirubin concentration and percent bilirubin/albumin satruation. The magnitude of changes in P50, 2,3-DPG, and hemoglobin concentration was similar in the phototherapy and control groups and was related to the expected changes with reference to postnatal age. These results suggest that phototherapy in vivo neither affects (fetal erythrocytic affinity for oxygen nor causes hemolysis. Pediatrics, 59:1027-1031, 1977 PHOTOTHERAPY, 2,3-DIPHOSPHOGLYCERATE, HEMOLYSIS, NEWBORN INFANT.

Diphosphoglyceric Acids↗
PubMed1976

Foam stability predictions of respiratory distress in infants delivered by repeat elective cesarean section.

Amniocentesis for assessment of lung maturity has been recommended before delivery by elective repeat cesarean section because respiratory distress may occur in infants delivered in this manner. To test this hypothesis, foam stability tests of amniotic fluid (84 cases) or gastric aspirate (25 cases) were used as interchangeable indexes of pulmonary maturity in 109 infants born by repeat elective cesarean section. Of the 81 infants with a positive foam stability test, only 2.5 per cent had transient respiratory distress, but 8.3 per cent with intermediate or negative foam stability tests had respiratory difficulty (P less than 0.025). The results support recommendations that fetal lung maturity should be assessed before elective repeat cesarean section to minimize the risk of respiratory morbidity.

Amniocentesis↗
PubMed1976

The inhibition of pulmonary maturation in the fetal rabbit by maternal treatment with phenobarbital.

Phenobarbital was administered to pregnant rabbits, 7 to 10 days before the delivery of their fetuses at 27 to 30 days of gestation. There were no differences in body weight or wet or dry lung weights between control animals and phenobarbital-treated pups at similar gestational ages. The phospholipid content (PLC) of the alevolar wash was lower in the phenobarbital-treated group, but there was no difference in the lung tissue PLC between the treated and control groups. Phenobarbital-treated pups had higher opening pressures and fewer lamellar bodies than the control animals. These data suggest that phenobarbital may have an inhibitory effect on surfactant production and/or release.

Animals↗
PubMed1976

Effects of fasting and theophylline on alanine-stimulated glucagon secretion in neonatal and infant sheep.

Plasma concentrations of glucose, alanine, and glucagon were measured after 24 hour fasting in newborn and infant sheep and in response to infusion of alanine alone and concurrently with theophylline. The plasma glucagon response to alanine was minimal in newborn sheep; in contrast, alanine produced a brisk response in plasma glucagon concentration in infant sheep. Glucose concentrations were unchanged in both groups. Theophylline enhanced blood glucagon and glucose responses to alanine in newborn animals but had minimal effects on the response of the infant sheep. These data, considered with earlier data in fetal sheep, suggest a progressive maturation of pancreatic islet alpha-cell glucagon secretion in the sheep during the postnatal period and suggest that the blunted glucagon response observed in the neonate is related to immaturity of the glucagon secretion mechanisms rather than deficient synthesis of the hormone. This immaturity may be related to impaired synthesis and/or enhanced degradation of cyclic adenosine monophosphate (cAMP) or to diminished responsiveness to cAMP.

Alanine↗
PubMed1976

The effects of large volume intravenous fluid infusion on neonatal renal function.

Twenty healthy infants weighing less than 2,000 gm were studied at low (3.6 ml/kg/hr) or high (10.3 ml/kg/hr) rates of intravenous infusion. Inulin clearance determined by the constant infusion method was greater at the high rate of infusion (p = less than 0.05). Inulin clearance in two groups of infants over 2,000 gm studies at the same low or high rates of infusion did not increase at the higher rate of infusion. Since the GFR in infants less than 2,000 gm depends partially on the rate of intravenous infusion, small, healthy preterm infants may benefit from a rate of fluid administration greater than the low rate. When studies at low and high rates of infusion were compared in the 20 infants less than 2,000 gm, the fractional urinary sodium excretion increased with the increased fluid load. Delivery of fluid from the proximal tubule (CH2O =Na per dl GFR) increased (p less than 0.005). Free-water clearance and the absolute volume of urine increased at the high rate of infusion. These data indicate that the healthy preterm infant less than 2,000 gm, like the adult, compensates by increasing free-water clearance and urine volume when challenged with a large fluid load. Although fluid changes of short duration are appropriately handled, the effect of continuous rapid infusion on water and sodium balance in infants of this size remains to be determined.

Body Fluids↗
PubMed1976

Renal function as a marker of human fetal maturation.

Sixty clinically well infants of various gestational ages (27 to 40 weeks) were studied from 24-40 hours after birth to evaluate glomerular filtration rate and renal excretion rate of sodium at various stages of fetal maturation. Creatinine clearance was directly related to gestational as (r = 0.643). Fractional sodium excretion was inversely related to gestational age (r = -0.755). The renal functions of small for gestational age infants were similar to those of full-term infants whose birth weights were appropriate for gestational age. The data showed that the glomerular functions of an infant below 32 weeks of gestation were more predominant than the tubular function resulting in a greater fractional sodium excretion rate and higher urinary Na loss in infants of this gestational age, when compared with the more mature infants.

Creatinine↗
PubMed1976

PAH clearance, sodium excretion, and PAH extraction ratio in acidotic near-term lambs treated with hypertonic sodium bicarbonate.

The electrolyte changes and renal hemodynamic adjustment to hypertonic sodium bicarbonate (NaHCO3) correction of a metabolic acidosis were studied in 4 neonatal lambs and in 2 controls. PAH clearance increased from 0.92 to 1.65 ml/min/kg (p less than 0.05), urine flow from 0.37 to 0.61 ml/min/kg (p less than 0.05), and Na excretion from 8.4 to 23.7 muEq/min/kg (p less than 0.05) during the NaHCO3 infusion. These increases were transient and returned to pre-infusion levels following NaHCO3 infusion. Calculation of Na intake and output revealed a net retention of 5.1 mEq/kg in the study lambs which was reflected in a rise of serum Na and osmolarity (Osm) during the post-NaHCO3 -infusion period. The extraction ratio of sodium p-aminohippurate (EPAH) and its relationship to arterial pH were studied in 4 additional lambs. The EPAH did not change with metabolic acidosis but for unknown reasons, the infusion of NaHCO3 resulted in a temporary depression of EPAH (p less than 0.001).

Acidosis↗
PubMed1976

Umbilical cord cutting triggers hypertriiodothyroninemia and nonshivering thermogenesis in the newborn lamb.

The present studies in the newborn sheep were undertaken to further clarify the mechanism or mechanisms for the early increases in serum thyroid hormone concentrations in the newborn as well as the significance of these changes to newborn nonshivering thermogenesis. Six groups of animals were studied to determine the influence of neonatal cooling, cord cutting, and the effects of thyrotropin-releasing hormone (TRH) and triiodothyronine (T3) injections. Group I newborns were delivered into room air with immediate cord cutting. Group II animals were delivered into room air and cord cutting was delayed 60 min. Group II animals were delivered into a 39 degrees water bath and maintained for 60 min with the umbilical cord intact; the cord was cut at the time of removal from the water bath...

Animals↗
PubMed1976

Acceleration of fetal lung maturation by aminophyllin in pregnant rabbits.

To test the hypothesis that fetal lung maturation can be accelerated by one of the xanthine derivatives, aminophyllin was given to 40 pregnant rabbits beginning on the 20th gestational day for a period of 7-10 days. The fetuses were delivered by cesarean section and fetal lung maturity was assessed by determining the biochemical, functional, and ultrastructural characteristics of aminophyllin-treated vs. control animals. The phospholipid content of the lung tissue homogenate from the aminophyllin-treated group was significantly higher than in the control subjects (saline injected) at 28 days of gestation (421 +/- 9 vs. 368 +/- 12 mug/mg wet wt, mean +/- SEM) and at 29 days of gestation (531 +/- 10 vs. 475 +/- 20). The alveolar wash phospholipid content of the aminophyllin-treated group was higher at 30 days (167 +/- 9 mug/mg dry wt, mean +/- SEM vs. 117 +/- 17). The lung compliance derived from pressure volume curves was also significantly higher in the aminophyllin-treated group when compared with controls at 27 days of gestation (0.023 +/- 0.0005 ml/cm H2O, mean +/- SEM vs 0.010 +/- 0.0002) and at 28 days of gestation (0.048 +/- 0.0003 vs 0.035 +/- 0.0006). There was no significant difference in the number of lamellar bodies in the type II cells between the aminophyllin-treated and the control groups. The data show that aminophyllin has accelerating effects on fetal lung maturation in rabbits when the drug is given to pregnant rabbits during the last 7-10 days of gestation.

Aminophylline↗
PubMed1976

Histidine decarboxylase activity in fetal intrauterine growth-retarded rats.

Fetal intrauterine growth retardation was induced in nine rats at 17 days' gestation by ligating the blood supply to one of the uterine horn. The 27 festuses from the uterine vessel ligated side were the intrauterine growth retarded fetuses (IUGR) and the 37 fetuses from the nonligated side were controls. The mean weight of the IUGR fetuses was 3.4 +/- 0.3 g which was significantly smaller (P less than 0.005) than the mean weight of the control fetuses, 4.0 +/- 0.3 g. Whole body histidine decarboxylase (HDC) activity was assayed by a radioisotope method. The HDC activity per g tissue was not correlated to body weight in the control fetuses. This is in contrast to the IUGR festuses in which the HDC per g tissue was significantly and inversely related to body weight (r - 0.48, P less than 0.001).

Animals↗
PubMed1976

Inulin clearance in the newborn infant: relationship to gestational and postnatal age.

Thirty-eight healthy newborn infants with gestational ages ranging from 25 to 42 weeks were studied at 2 days to 9 weeks postnatal age to evaluate the rate of glomerular maturation after birth. Glomerular function was assessed by a constant infusion method for inulin clearance (Cin). Cin was nearly identical when measured by the traditional clearance method and by the constant infusion technique. The Cin of 22 infants 2-3 days old ranged from 0.6 to 17.9 ml/min and was directly related to gestational age (r = 0.81, P less than 0.001). For 26 infants studied at 1-9 weeks of age, Cin was directly proportional to conceptual (gestational and postnatal) age (r = 0.89, P less than 0.001), and approximated that of infants of similar gestational age studied at 2-3 days of age.

Aging↗