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Biomedical subjects

W Oh

Publications and source records attributed to W Oh.

At least 181 records · Page 10Linked to original sources
PubMed1985

Economic analysis of regionalized neonatal care for very low-birth-weight infants in the state of Rhode Island.

Cost-benefit analysis was utilized to evaluate the economic outcome of regionalized neonatal care in the state of Rhode Island, with specific reference to newborns weighing less than 1,500 g at birth. Two time periods consisting of two calendar years each, were analyzed: 1974 to 1975 (initiation of perinatal regionalization) and 1979 to 1980 (regionalization established). The neonatal mortality for infants weighing between 501 and 1,500 g decreased significantly between the two time periods. Neurodevelopmental morbidity was unchanged. The costs per survivor (hospital charges plus estimated costs of long-term care of handicapped survivors) were consistent over the time periods studied. The estimated benefits per survivor increased between the time periods, although this increase was not statistically significant. Benefits outweighed costs in both study periods. When one compares the economic data of 1974 to 1975 with that of 1979 to 1980, the increase in the absolute number of normal survivors since the establishment of regionalized neonatal care has resulted in benefits surpassing costs by $2 million (a greater than twofold increase). Regionalized neonatal care in the state of Rhode Island has had a positive economic outcome.

Child Development↗
PubMed1985

Determinants of mother-infant interaction in adolescent mothers.

Mother-infant interactions of adolescent and nonadolescent mothers are compared, and the impact of maternal age, ego development, education, and child care support on these interactions is examined. Thirty primiparous, white, lower- to middle-class mothers (half less than or equal to 17 years) and their healthy full-term infants (8 months) were studied. Interactions were videotaped during face-to-face interactions and teaching sessions. Child care support and ego development were assessed. During face-to-face interactions, only one difference was found between adolescent and nonadolescent mothers: nonadolescent mothers showed more positive affect toward infants. During teaching, nonadolescent mothers talked more, showed more positive affect toward infants, and demonstrated tasks more often. Individual differences during face-to-face interactions were more related to mothers' ego development and support whereas teaching interactions were mostly associated with maternal age. Thus, maternal age was a stronger predictor of interactive style during teaching. This may partially explain noted cognitive deficits in infants of teenage mothers. However, individual differences among all mothers in ego development, education, and support were significantly related to interactions. Thus, teenage mothers with less education and support and lower ego development may represent a higher risk subgroup of adolescent mothers providing less optimal care-giving environments for their infants.

Adolescent↗
PubMed1984

Increased immunoreactive erythropoietin in cord serum after labor.

Since several hours of hypoxemia in fetal animals is sufficient to cause an increase in the plasma erythropoietin level and since labor may be associated with fetal hypoxemia, this study was undertaken to determine if erythropoietin levels in cord blood were higher in fetuses subjected to labor. Two groups of term (37 to 41 weeks) singleton pregnancies were compared: (1) those delivered by elective repeat cesarean section without prior labor (n = 18) and (2) those delivered vaginally (n = 23). Erythropoietin was measured by a radioimmunoassay in which a highly purified human erythropoietin (70,000 U/mg of protein) was used and which has a sensitivity limit of 4 to 5 mU/ml. The mean cord serum erythropoietin level was higher in pregnancies with labor (46 +/- 34 mU/ml, mean +/- SD) compared to those without (26 +/- 10, p less than 0.02). There were no differences between the two groups for maternal age, gestational age, birth weight, infant sex, or Apgar scores. No association of erythropoietin with either gestational age or sex was found. In 11 pregnancies without labor, comparisons were made among simultaneously obtained samples of umbilical arterial plasma, umbilical venous plasma, and mixed cord serum. Although there were no differences between umbilical arterial and umbilical venous plasma erythropoietin levels (21.3 +/- 9.3 versus 19.0 +/- 7.8 mU/ml), mixed cord serum was inexplicably higher (24.4 +/- 9.5 mU/ml, p less than 0.01). We concluded that in uncomplicated pregnancies the duration and intensity of labor are sufficient to cause an increase in the fetal erythropoietin level at delivery.

Adolescent↗
PubMed1984

Aminophylline reduces cerebral blood flow velocity in low-birth-weight infants.

Cerebral blood flow decreases substantially in the adult after a single bolus injection of aminophylline. To determine if the cerebral circulation of the low-birth-weight infant behaves in a similar manner, we measured cerebral blood flow velocity (CBFV) in the anterior cerebral arteries of nine infants treated with an intravenous bolus dose of 5 mg/kg of body weight of aminophylline. A reduction in CBFV of 21% and 17% was observed at 60 and 120 minutes following the aminophylline administration. There was a concurrent substantial reduction in PCO2 from 45 +/- 7 to 39 +/- 7 mm Hg before and 120 minutes after the aminophylline administration, respectively. The reduction in CBFV may be the result of a reduction in PCO2 resulting from aminophylline treatment.

Aminophylline↗
PubMed1984

The renal response to acute asphyxia in spontaneously breathing newborn lambs.

The effects of acute asphyxia on neonatal renal function were examined in spontaneously breathing newborn lambs. 25 min of asphyxia were induced by addition of a respiratory dead space to reduce PaO2 to 41 +/- 3 mm Hg, pH to 7.03 +/- 0.05 and increase PaCO2 to 68 +/- 5 mm Hg (mean +/- S.E.M.). Glomerular filtration rates did not change significantly during or after asphyxia. Immediately following asphyxia significant (P less than 0.05) increases over the baseline were found in urinary flow rates, fractional sodium excretion, absolute sodium excretion and osmolar clearances. These changes were in part secondary to significant (P less than 0.05) increases in plasma glucose concentrations associated with increases (P less than 0.05) in circulating arterial catecholamine concentrations. The percentage of tubular reabsorption of glucose decreased significantly (P less than 0.05) and urinary glucose excretion increased significantly. Renal blood flow was unchanged. Therefore, asphyxia induced significant hyperglycemia which contributed to the concomitant natriuresis and osmotic diuresis in these newborn lambs.

Acute Disease↗
PubMed1984

Cerebral blood flow in the newborn lamb with polycythemia and hyperviscosity.

We measured hematocrit, whole blood viscosity, arterial oxygen content, and cerebral blood flow in seven newborn lambs in which polycythemia and hyperviscosity were induced by partial exchange transfusion with packed red blood cells from a donor lamb. After the exchange transfusion, the hematocrit, whole blood viscosity, and arterial oxygen content were significantly elevated, whereas cerebral blood flow was reduced from baseline measurements. Sodium nitrite was then infused to reduce the arterial oxygen content to baseline values while the hematocrit and viscosity remained elevated. Under this condition, cerebral blood flow returned to baseline values. Oxygen delivery to the brain remained constant throughout the study. These results indicate that the reduction of cerebral blood flow in neonatal polycythemia and hyperviscosity is a physiologic response to increased arterial oxygen content and not a result of hyperviscosity.

Animals↗
PubMed1984

Effect of polycythemia on gastrointestinal blood flow and oxygenation in piglets.

Gastrointestinal blood flow and oxygenation were measured before and after the induction of polycythemia in newborn piglets. Sixty minutes after exchange transfusion with age-matched packed red blood cells, hematocrit and in vitro whole blood viscosity increased, while 51Cr-measured blood volume did not change. Cardiac output and total gastrointestinal blood flow (the sum of stomach, jejunum, ileum, and colon blood flows) decreased a similar degree after exchange transfusion, although the reduction in total gastrointestinal blood flow was not uniform in all regions of the gastrointestinal tract. Specifically, blood flow to the stomach and mucosa-submucosa layer of the small bowel decreased, whereas that to the colon and muscularis-serosa layer of the small bowel remained unchanged. Gastrointestinal O2 delivery increased after exchange transfusion because of the increase in arterial O2 content consequent to polycythemia. The arteriovenous O2 content difference remained unchanged following exchange transfusion, and gastrointestinal O2 consumption thus decreased 49 +/- 2%. After a test meal, postprandial values for gastrointestinal blood flow and oxygenation in polycythemic piglets increased to levels similar to postprandial values reported previously in normal newborn piglets.

Animals↗
PubMed1984

Gastrointestinal blood flow and oxygen consumption in the newborn lamb: effect of chronic anemia and acute hypoxia.

The purpose of this study was to investigate the compensatory change in circulation and oxygenation of the newborn lamb gastrointestinal (GI) tract in response to anemic and hypoxic hypoxemia. Radiolabeled microspheres were used to measure blood flow. We subjected the newborn lamb to a 30-35% reduction in hematocrit 4 d before study and to a 10% oxygen environment for 30 min during the study to induce chronic anemic and acute hypoxic hypoxemia, respectively. The circulatory and oxygenation responses were measured 1 h after a standard milk feeding in all cases. During the experimental periods, no change in total GI blood flow was observed. Because of a failure to augment blood flow during hypoxemia, O2 delivery to the GI tract decreased significantly. Despite this, GI O2 consumption was not compromised because tissue O2 extraction by the GI tract rose significantly. The response of the newborn lamb GI tract to hypoxemia after feeding is augmentation of O2 extraction. The newborn's GI tract did not regulate local GI blood flow.

Anemia↗
PubMed1984

Atropine prevents increases in brain blood flow during hypertension in newborn piglets.

Cerebral hyperperfusion associated with hypertension, may play an important role in the pathogenesis of intraventricular hemorrhage in preterm infants. To examine the effect of hypertension on changes in total and regional brain blood flow (BBF), we increased the mean arterial blood pressure (MABP) in nine awake newborn piglets by an infusion of 0.7 mg/kg of metaraminol bitartrate (Aramine) (group I) and studied cerebral circulatory changes. In order to prevent the Aramine-associated bradycardia, we pretreated nine other piglets with atropine, which produced a higher level of hypertension (group II). MABP and BBF were measured and cerebral vascular resistance (CVR) was calculated during baseline, the Aramine infusion, and twice at decreasing MABP following the discontinuation of the Aramine infusion. In group I, the significant increase in MABP from 68 +/- 3 to 100 +/- 3 mm Hg (mean +/- SEM) during the Aramine infusion resulted in a significant increase in BBF (98 +/- 9 to 118 +/- 11 ml X min-1 X 100 g-1). MABP decreased significantly (although remained significantly above baseline levels), when Aramine was discontinued; however, total BBF remained elevated. CVR increased during the Aramine infusion, but decreased significant (versus the Aramine-infused state) in the post-Aramine period. Regional BBF increased significantly to the cerebrum and cerebellar cortex, but remained unchanged to the other regions including the brain stem. In group II, the Aramine infusion resulted in a significantly greater increase in MABP, a sustained increase in vascular resistance, and no increase in total BBF. Thus, atropine prevents increased BBF during hypertension in the newborn piglet.

Animals↗
PubMed1984

The effects of variations in PaCO2 on brain blood flow and cardiac output in the newborn piglet.

The acute effects of normoxemic hypocarbia and hypercarbia were examined in six newborn piglets. Brain blood flow was maintained during hypocarbia until extremely low PaCO2 (less than 15 mm Hg) levels were achieved at which time total brain and cerebral blood flow decreased significantly from baseline values. Blood flow to the thalamus, cerebellum and brain stem was unchanged from baseline conditions during hypocarbia. This suggests that the newborn brain is relatively insensitive to moderate degrees of hypocarbia. Extreme hypocarbia (PaCO2 less than 15 mm Hg) was associated with a significant increase in heart rate, accompanied by a significant decrease in mean arterial blood pressure; however, cardiac output was not significantly different from baseline determinations. Hypercarbia with normoxemia was associated with significant increases in total brain blood flow, with greater blood flow to the brain stem, cerebellum, and thalamus than to the cerebrum. The percentage of cardiac output received by the brain was also significantly increased, although total cardiac output was unchanged. This demonstrates that the newborn cerebral vasculature is sensitive to hypercarbia and that regional differences in sensitivity may account for the greater increments in blood flow to the caudal portions of the brain than that to the cerebrum.

Animals↗
PubMed1984

Cost-benefit analysis of neonatal intensive care for infants weighing less than 1,000 grams at birth.

Cost-benefit analysis was performed on the care of 247 infants weighing between 500 and 999 g at birth, admitted to Women and Infants Hospital of Rhode Island between January 1977 and December 1981. The neonatal mortality was 68%. Eighty-seven percent of the survivors were evaluated neurodevelopmentally for 1 to 5 years: 74% were normal or minimally impaired, 10% were moderately impaired, and 16% were severely handicapped. Using these data in conjunction with cost information obtained from the hospital and therapeutic care facilities for handicapped children, total lifetime costs for the care of these infants were estimated. In 1982 dollars, present values of costs ranged from $362,992 per survivor for those weighing between 600 and 699 g to $40,647 per survivor for those weighing between 900 and 999 g, resulting in an inverse correlation between cost per survivor and birth weight (P less than .001). We estimated present values of expected lifetime earnings per survivor, with a range of zero earnings for infants between 500 and 699 g, to $77,084 for those with birth weight of 900 to 999 g. It is concluded that from the standpoint of cost-benefit analysis as was used for this study population, neonatal intensive care may not be justifiable for infants weighing less than 900 g at birth.

Adolescent↗
PubMed1984

Glucose kinetics in glucose-infused small for gestational age infants.

To evaluate the maturation of glucose homeostasis in the small for gestational age (SGA) neonate, glucose kinetics were measured with 78% enriched D-[U-13C]glucose by the prime plus constant infusion technique in nine SGA infants and compared with the rate obtained in seven term appropriate for gestational age infants and 13 preterm appropriate for gestational age infants. All of the infants had received glucose intravenously from birth and continued to receive the glucose infusion throughout the study. Fasting plasma glucose and plasma insulin concentrations and plasma [13/12C]ratios were measured during the steady state turnover period. From this data, the glucose production rate was derived. During the turnover period, the SGA and both groups of appropriate for gestational age infants had similar average plasma glucose, plasma insulin, plasma glucagon concentrations, and similar persistent rates of glucose production during glucose infusion. We conclude that under stimulation of glucose infusion, the SGA infant and his AGA counterpart have similar hormonal regulatory responses as well as functional integrity in handling glucose during the second day after birth.

Blood Glucose↗
PubMed1984

Effect of acidosis on bilirubin deposition in rat brain.

The effect of metabolic and respiratory acidosis on bilirubin and albumin entry into the brain was studied in 24 awake and unanesthetized rats. Hyperbilirubinemia was established by infusion of unconjugated bilirubin at a rate of 30 mg/kg/h for three hours. After two hours, metabolic acidosis was produced in eight rats by infusion of 0.5 N hydrochloric acid at a rate of 0.02 mL/g/h. This reduced the pH level to 7.03 +/- 0.01 (mean +/- SEM) with a normal value for PCO2. Respiratory acidosis was produced in another group of eight animals who breathed 20% CO2 in a balanced gas mixture for the last hour of the study period. This resulted in a reduction of pH to 7.04 +/- 0.01 with PCO2 of 100.4 +/- 2.3 mm Hg. A third group of eight rats served as controls and were given equal volumes of saline infusion. No increase in brain bilirubin or brain albumin was found in the group with metabolic acidosis, but in the group with respiratory acidosis both bilirubin and albumin concentrations in the brain increased significantly. No significant differences were found between the groups in serum total or apparent unbound bilirubin, albumin, or osmolality. The results indicate that a brief period of acidosis per se does not increase bilirubin entry into the brain, but hypercarbia does so by opening of the blood-brain barrier.

Acidosis↗
PubMed1983

The effect of carotid artery ligation on brain blood flow in newborn piglets.

The common carotid artery is often ligated and used to introduce a left ventricular catheter to perform blood flow studies with radioactive-labeled microspheres. In order to determine whether this procedure alters brain blood flow, 6 newborn piglets were studied. Five measures of brain blood flow were performed in each study; once before and then 4 times (at 20 min intervals) after ligation of the left common carotid artery. Ventilation was controlled using nitrous oxide and oxygen while the hematocrit was kept stable by intermittent transfusions. Brain blood flow was found to remain constant over the duration of the study. No differences in blood flow were found between the right and left sides of the brain. The data indicate that use of a common carotid artery for purposes of left ventricular catheterization do not alter the blood flow to the brain when the microsphere method is used. This facilitates surgical preparation when small animals are used for studies of brain blood flow hemodynamics.

Animals↗
PubMed1983

Fetal polycythemia and hyperviscosity: effect on umbilical blood flow and fetal oxygen consumption.

To evaluate the effect of fetal polycythemia and hyperviscosity on fetal oxygen transport, we induced those conditions in eight chronically instrumented fetal lambs by isovolemic exchange transfusion with packed red cells obtained from a donor ewe. This procedure resulted in polycythemia and hyperviscosity without altering fetal arterial blood oxygen content. The fetuses were studied at 1 and 48 hours after polycythemia and hyperviscosity. In spite of decreased oxygen delivery to the fetus, the fetal oxygen consumption was unchanged because of an increase in oxygen extraction by the fetus.

Animals↗
PubMed1983

Glucose kinetics in nondiabetic and diabetic women during the third trimester of pregnancy.

Glucose kinetics were measured with 78% enriched D-[U-13C] glucose by the prime constant infusion technique during the third trimester of pregnancy in nine nondiabetic women, nine insulin-dependent diabetic women, six gestational diabetic women, and five control women (nonpregnant, nondiabetic) after an overnight fast. The patients not dependent on insulin were diagnosed as diabetic by oral glucose tolerance tests with the use of O'Sullivan and Mahan's criteria as modified by Carpenter and Coustan during the third trimester. The turnover studies were repeated post partum (6 weeks to 5 months after delivery) in 14 of the 24 pregnant subjects. All pregnant groups had a progressive fall in plasma glucose concentration during the study, but there was a steady state of plasma glucose concentration during the turnover period. In comparison to the control subjects, both the pregnant nondiabetic and pregnant insulin-dependent diabetic women had significantly higher plasma insulin concentrations throughout the study (p less than 0.05). There were no differences in the glucose turnover rate between any of the pregnant groups (1.7 +/- 0.2 mg . kg-1 min-1 in pregnant nondiabetic women; 1.5 +/- 0.2 mg . kg-1 min-1 in pregnant insulin-dependent diabetic women; and 2.1 +/- 0.4 mg . kg-1 min-1 in gestational diabetic women) and the control group of women (1.8 +/- 0.2 mg . kg-1 min-1) (mean +/- SEM). When the pregnant patients were studied post partum, the glucose turnover rate was similar when referenced to body weight; however, because of a 9.6% to 14.5% fall in weight post partum, the absolute values were higher in the pregnant women. We conclude that, in the basal state after an overnight fast, (1) both nondiabetic and diabetic patients accelerated their glucose turnover rate during pregnancy to provide for increased maternal and fetoplacental metabolic requirements, and (2) in the diabetic subjects the nearly normal plasma glucose and insulin concentrations and other metabolic parameters, as well as the glucose turnover rate, suggested good metabolic control during pregnancy in most of the insulin-dependent and in all of the gestational diabetic patients.

Adult↗
PubMed1983

Glucose kinetics in infants of diabetic mothers.

Glucose kinetic studies were performed to define the glucose turnover rate with 78% enriched D-[U-13C] glucose by the prime constant infusion technique at less than or equal to 6 hours of age in nine infants of diabetic mothers (four insulin-dependent and five chemical diabetic patients) at term. Five normal infants were studied as control subjects. All infants received 0.9% saline intravenously during the study with the tracer. Fasting plasma glucose, insulin, and glucose13/12C ratios were measured during the steady state, and the glucose turnover rate was derived. The average plasma glucose concentration was similar during the steady state in the infants of the diabetic mothers and in the control infants, and the glucose turnover rate was not significantly different among the groups: 2.3 +/- 0.6 mg . kg-1 min-1 in infants of insulin-dependent diabetic patients; 2.4 +/- 0.4 mg . kg-1 min-1 in infants of chemical diabetic patients; and 3.2 +/- 0.3 mg . kg-1 min-1 in the control subjects. Good control of maternal diabetes evidenced by the normal maternal hemoglobin A1c and plasma glucose concentration at delivery and cord plasma glucose concentration resulted in glucose kinetic values in the infants of diabetic mothers that were indistinguishable from those of control subjects. The data further support the importance of good control of the diabetic state in the pregnant woman to minimize or prevent neonatal hypoglycemia.

Blood Glucose↗