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Biomedical subjects

W Oh

Publications and source records attributed to W Oh.

At least 55 records · Page 3Linked to original sources
PubMed1997

Vitamin A to prevent bronchopulmonary dysplasia in very-low-birth-weight infants: has the dose been too low? The NICHD Neonatal Research Network.

OBJECTIVE: Inconsistent effects of vitamin A supplementation on prevention of bronchopulmonary dysplasia have been reported. Meta-analysis of these reports resulted in a relative risk of 0.69-1.02 for death or bronchopulmonary dysplasia associated with vitamin A supplementation. Effective dosage regimens or serum retinol concentrations have not been determined in previous reports. The purpose of this pilot study was to define a vitamin A regimen that produces serum retinol concentrations of 25-55 micrograms/dl. STUDY DESIGN: In this three-phase study, 91 infants (mean birth weight 799-864 g) were enrolled. Vitamin A was administered three times/week for 4 weeks at an average daily dose of 986-2143 IU/day. Physical examinations were performed and serum retinol specimens were collected weekly to assess clinical signs of toxicity. RESULTS: The majority of serum retinol concentrations remained < 25 micrograms/dl until an intramuscular vitamin A dose of 5000 IU/dose three times/week was used. No clinical signs of toxicity were associated with the higher dosage and higher serum concentrations of vitamin A. CONCLUSION: A large clinical trial of vitamin A supplementation with 5000 IU/dose three times/week (25-114% more than the dose used in the three published clinical trials) is needed to assess whether vitamin A supplementation safely reduces the risk of bronchopulmonary dysplasia in very-low-birth-weight infants.

Adrenal Cortex Hormones↗
PubMed1997

Persistent glucose production and greater peripheral sensitivity to insulin in the neonate vs. the adult.

Insulin resistance has been reported to partially explain the clinical appearance of neonatal hyperglycemia. To determine the relative resistance to insulin of glucose production vs. glucose utilization, the euglycemic hyperinsulinemic clamp technique was employed for the first time in the human neonate and was combined with stable isotopic determination of glucose production and glucose utilization. The basal rates of glucose production and glucose utilization were determined, after which each neonate was clamped at his or her own euglycemic glucose concentration while receiving regular human insulin at one rate of 0.2, 0.5, 1.0, 2.0, or 4.0 mU. kg-1.min-1. Persistent glucose production (> or = 1 mg.kg-1.min-1) during the clamp was recorded for all groups. A significant increase in the glucose infusion rate (P < 0.001) and in percent glucose utilization (P < 0.01) occurred in the 2.0 and 4.0 mU.kg-1.min-1 insulin groups. Metabolic clearance rate of insulin was significantly greater in the neonate compared with the adult at the 2.0 mU.kg-1.min-1 insulin infusion rate (P = 0.036). Our results indicate that, in contrast to the adult, the neonate has persistent glucose production (P = 0.001) and greater peripheral sensitivity to insulin (P = 0.015).

Adult↗
PubMed1997

Effects of nitric oxide synthesis inhibition on mesenteric perfusion in young pigs.

We tested the hypothesis that nitric oxide (NO) modulates postprandial hyperemia in young pigs. To test this hypothesis, we studied five groups of 3-wk-old pigs: group 1: milk fed, N(G)-monomethyl-L-arginine (L-NMMA) and L-arginine (L-Arg) treated (n = 10); group 2: milk fed, placebo treated (n = 8); group 3: water fed, L-NMMA and L-Arg treated (n = 6); group 4: water fed, placebo treated (n = 4); and group 5: fasted sham fed, L-NMMA and L-Arg treated (n = 6). After catheter placement and electromagnetic flow probe instrumentation of the mesenteric artery, systemic blood pressure and mesenteric artery blood flow were measured during preprandial baseline, postprandial, and postprandial intra-arterial L-NMMA- and L-Arg-infused study periods. The same measurements were made in the milk- and water-fed placebo-treated groups except that diluent replaced the L-NMMA and L-Arg infusions. In the milk- and water-fed placebo-treated groups, a significant (analysis of variance, P < 0.05), postprandial hyperemia was observed. The change in blood flow was greater (P < 0.05) in the milk-fed group than in the water-fed group. Inhibition of NO synthesis with L-NMMA diminished (P < 0.05) the hyperemic responses to both water and milk feeding and resulted in a decrease (P < 0.05) in mesenteric artery perfusion in the fasted sham-fed state. We conclude that, in young pigs, NO is a modulator of mesenteric vascular tone in both the postprandial and fasted states.

Animals↗
PubMed1997

Magnesium is a cerebrovasodilator in newborn piglets.

We tested the hypothesis that, in newborn piglets, magnesium results in a dose-dependent prostanoid-mediated cerebrovasodilation. Pial arterioles (50-200 microns in diameter) were serially measured, and cortical subarachnoid cerebrospinal fluid (CSF) was collected for radioimmunoassay of 6-ketoprostaglandin F1 alpha (6-keto-PGF1 alpha, hydrolysis product of prostacyclin) and thromboxane B2 (TxB2, metabolite of thromboxane A2) before and after CSF containing 1.2, 2.4, 4.8, and 9.6 mM MgCl2 was suffused over the parietal cortex under a closed cranial window in twelve 2- to 4-day-old piglets. Magnesium suffusion resulted (P < 0.05) in a dose-dependent pial arteriolar vasodilation. The increase in vessel diameter was greater (P < 0.001) with 2.4, 4.8, and 9.6 mM than with 1.2 mM concentration of magnesium. The increase in vessel diameter with 9.6 mM was also greater (P < 0.001) than with the 2.4 mM concentration of magnesium. Magnesium suffusion did not result in changes in cortical CSF prostanoid concentrations. The effect of intravenous indomethacin (5 mg/kg) on cyclooxygenase inhibition in the pial arterioles was confirmed by a 24 +/- 3% decrease in vessel diameter at the baseline (1.2 mM) magnesium concentration. In contrast, cyclooxygenase inhibition with intravenous indomethacin did not attenuate the magnesium-induced cerebrovasodilation. We conclude that in new born piglets magnesium suffusion over the parietal cortex results in a dose-dependent cerebrovasodilation that is most likely not mediated by prostanoids.

Animals↗
PubMed1997

Breastfeeding infants who were extremely low birth weight.

OBJECTIVE: To compare the clinical effect of breastfeedings and bottle feedings in extremely low birth weight (ELBW) infants (birth weight </=800 g). METHODS: A total of 12 ELBW infants (mean birth weight, 672 +/- 95 g; mean gestation, 26 +/- 2 weeks) served as their own controls in this prospective study comparing physiologic parameters during bottle and breastfeeding. The infants were put to breast the same week they began on bottle feedings of human milk or premature infant formula (mean gestation, 35 weeks). One breastfeeding and one bottle feeding were observed each day for 10 days. Pre- and postfeeding weights were measured, and oxygen saturation, respiratory rate, heart rate, and axillary temperature were monitored continuously and recorded every minute during feedings. RESULTS: The infants demonstrated a higher oxygen saturation and a higher temperature during breastfeeding than during bottle feeding, and were less likely to desaturate to <90% oxygen during breastfeeding. Mean weight gain was greater during bottle feeding than during breastfeeding (31 vs 9 g). CONCLUSIONS: Breastfeeding the ELBW infant is desirable from a standpoint of improved physiologic responses, but such practice requires breastfeeding support and possible supplementation to optimize weight gain.

Bottle Feeding↗
PubMed1997

Outbreak and control of a rotaviral infection in a nursery.

Neonatal rotaviral infection generally causes an asymptomatic or mild illness. Once introduced into a nursery, it is very difficult to eradicate. We prospectively studied an outbreak of rotavirus infection in a normal newborn nursery from October 1994 through May 1995. Stool samples from infants more than 24 hours old were tested for rotaviral infection, either weekly, biweekly, or monthly. Rotavirus was identified in 164 (16%) of 1,037 tested neonates. Ninety-four (57%) rotavirus-positive neonates became symptomatic: 56 had diarrhea, 26 developed fever (rectal temperature > 38 degrees C), 25 experienced vomiting, 17 showed poor feeding, and 14 had an elevated core temperature. In total, 24 neonates were evaluated for suspected sepsis. RNA electropherotyping of samples from 91 neonates revealed infection by the same rotavirus strain in all cases. This strain differed from that isolated from 64 rotavirus-infected infants and toddlers in the pediatric ward during the same period. Infection control procedures (hand washing, isolation of infected neonates, and careful management of diapers) and early discharge of uninfected neonates were instituted, and the outbreak was eradicated 8 months after the onset. Our findings indicate that many rotavirus-infected term neonates become symptomatic and have signs suggestive of sepsis. Extended hospital stay may be an important factor in promoting rotaviral transmission. Thus, early discharge may be an additional effective method of controlling rotavirus outbreaks in a nursery.

Cross Infection↗
PubMed1996

Behavioral intervention and post-natal growth in full-term intrauterine growth retarded (IUGR) infants.

The purpose of this study was twofold: (1) to describe the patterns of post-natal growth in full-term infants as a function of IUGR and (2) to assess the impact of an individualized behavioral feeding intervention with the mothers on these patterns of infant growth. Eighty-eight (88) full-term infants, including 54 with IUGR, half of whom received behavioral intervention were included. Weight, length, skinfold thickness, head circumference and Ponderal Index were measured at birth and at 1, 4, 8, 12, and 18 months. Results show positive intervention effects between birth and 1 month in weight, length, skinfold thickness, and Ponderal Index. However, there were no intervention effects at subsequent ages. No evidence was found for catch-up growth in full-term IUGR infants in weight, length, and head circumference. We conclude that an individualized behavioral feeding intervention can accelerate early growth in IUGR infants, but the positive effects on growth are only seen while the intervention lasts (between birth and 1 month). On most parameters of physical growth, there is no lasting catch-up growth over the first 18 months in IUGR full-term infants.

Body Height↗
PubMed1996

Effects of maternal hypertension in very-low-birth-weight infants.

OBJECTIVE: To determine the effects of mild vs severe maternal hypertension on the neonatal morbidity of very-low-birth-weight infants. DESIGN: Cohort case-control study. SETTING: Tertiary care center neonatal intensive care unit. PATIENTS: Thirty-nine infants born to mothers with maternal hypertension (blood pressure > or = 140/90 mm Hg on 2 occasions during pregnancy) among 267 very-low-birth-weight infants (< or = 1250 g) admitted to the special care nursery between January 1, 1991, and December 31, 1992. Each infant was matched for gestational age and survival to 2 control infants born to normotensive mothers. The cohort included 11 infants of mothers with mild hypertension, 28 with severe hypertension, and 78 controls. MAIN OUTCOME MEASURES: Late and variable decelerations, incidence of small size for gestational age, respiratory distress syndrome, intraventricular hemorrhage, patent ductus arteriosus, apnea, ventilator therapy, oxygen requirement, and bronchopulmonary dysplasia. RESULTS: The mild and severe maternal hypertension groups had significantly lower birth weights and more infants small for gestational age than did controls. The incidence of respiratory distress syndrome, however, was significantly lower in infants of mothers with mild hypertension than in those with mothers with severe hypertension. Those in the mild group had fever days of ventilatory therapy and lower oxygen requirements than both the infants in the severe group and control infants. The incidence of apnea in the mild hypertension group was significantly lower than that in the severe hypertension group. CONCLUSIONS: Although mothers with both mild and severe hypertension have an increased incidence of infants small for gestational age, the infants born to mothers with mild hypertension had less respiratory distress syndrome, apnea, ventilator therapy, oxygen requirements, and bronchopulmonary dysplasia when compared with very-low-birth-weight infants born to mothers with severe hypertension.

Adult↗
PubMed1996

Attitudes about sibling visitation in the neonatal intensive care unit.

OBJECTIVE: To survey the attitudes and recommendations of staff members before and after the implementation of sibling visitation in a neonatal intensive care unit. DESIGN: Staff survey conducted before (1992) and after (1993) the implementation of sibling visitation. SETTING: A perinatal tertiary care center. PARTICIPANTS: Staff members including physicians, nurses, respiratory therapists, social workers, and unit clerks (n = 139 in 1992; n = 120 in 1993). MEASUREMENTS AND MAIN RESULTS: A 7-point Likert scale survey (1 = strongly disagree: 7 = strongly agree) was designed for the study. In both 1992 and 1993, the staff most strongly agreed that visitation requires special supervision, should have designated times, increases sibling knowledge, enhances sibling attachment to the baby, and increases family satisfaction. Wilcoxon rank sum tests comparing the staff across the 2 years indicated substantial attitudinal changes in favor of sibling visitation, including less perceived interference with nursing care and nursery routines (P < .01) and less concern about the infants' risk of respiratory infection and exposure to chickenpox (P < .05). There was greater attitudinal agreement between disciplines in 1993 than in 1992, suggesting better staff consensus about sibling visitation following its implementation. The recommended minimum age for visitation was 4.67 years and 4.05 years in 1992 and 1993, respectively. Brief visits of 10 to 15 minutes' duration were consistently recommended. Staff rated the sibling visitation program as successful (median = 6) on a scale ranging from 1 (very poor) to 7 (very successful). CONCLUSIONS: Staff members have concerns about sibling visitation that include increased risk of infection, organization, and supervision. A sibling visitation program that addresses these concerns can be successfully implemented and supported by staff, thereby fostering family-centered care in the neonatal intensive care unit.

Attitude↗
PubMed1996

Comparison of skin-to-skin contact with standard contact in low-birth-weight infants who are breast-fed.

OBJECTIVE: To evaluate the effects of maternal-infant skin-to-skin contact (SSC) vs standard contact (SC) on low-birth-weight infants' physiological profile, maternal milk production, and duration of breast-feeding. DESIGN: Prospective, randomized, interventional study with cohort followed up for 6 months after discharge from the hospital. SETTING: Special care nursery with follow-up telephone calls after discharge from the hospital. PATIENTS: Fifty infants, with birth weights less than 1500 g and whose mothers planned to breast-feed, randomized to 2 groups: SSC (experimental) and SC (control). INTERVENTION: In the SSC group, infants were clothed in diaper and held upright between mothers' breasts; both mother and infant were covered with a blanket. In the SC group, infants were clothed, wrapped in blankets, and held cradled in mother's arms. MAIN OUTCOME MEASURES: Infant physiological data, ie, oxygen saturation, heart rate, respiratory rate, and axillary temperature; maternal milk production; and duration of breast-feeding. RESULTS: Oxygen saturation was higher during SSC than during SC (P < .001); 11% of the oxygen saturation recordings during SSC vs 24% during SC indicated the values less than 90% (P < .001). A more stable milk production was noted in the SSC group. No differences were noted in infant temperature, heart rate, or respiratory rate. Ninety percent of mothers in the SSC group vs 61% in the SC group continued breast-feeding for the duration of the infants' hospitalization (P < .05), and 50% in the SSC group vs 11% in the SC continued breast-feeding through 1 month after discharge (P < .01). CONCLUSIONS: During SSC with their mothers, low-birth-weight infants maintain a higher oxygen saturation and are less likely to have desaturation to less than 90% oxygen than are infants exposed to SC. Mothers in the SSC group are more likely to continue breast-feeding until 1 month after discharge.

Adult↗
PubMed1996

Late-onset sepsis in very low birth weight neonates: a report from the National Institute of Child Health and Human Development Neonatal Research Network.

OBJECTIVE: Late-onset sepsis (occurring after 3 days of age) is an important problem in very low birth weight (VLBW) infants. To determine the current incidence of late-onset sepsis, risk factors for disease, and the impact of late-onset sepsis on subsequent hospital course, we evaluated a cohort of 7861 VLBW (401 to 1500 gm) neonates admitted to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal Research Network centers during a 32-month period (1991 to 1993). METHODS: The NICHD Neonatal Research Network maintains a prospectively collected registry of all VLBW neonates cared for at participating centers. Data from this registry were analyzed retrospectively. RESULTS: Of 6911 infants who survived beyond 3 days, 1696 (25%) had one or more episodes of blood culture-proven sepsis. The vast majority of infection (73%) were caused by gram-positive organisms, with coagulase-negative staphylococci accounting for 55% of all infections. Rate of infection was inversely related to birth weight and gestational age. Complications of prematurity associated with an increased rate of infection included intubation, respiratory distress syndrome, prolonged ventilation, bronchopulmonary dysplasia, patent ductus arteriosus, severe intraventricular hemorrhage, and necrotizing enterocolitis. Among infants with bronchopulmonary dysplasia, those with late-onset sepsis had a significantly longer duration of mechanical ventilation (45 vs 33 days; p <0.01). Late-onset sepsis prolonged hospital stay: the mean number of days in the hospital for VLBW neonates with and without late-onset sepsis was 86 and 61 days, respectively (p <0.001). Even after adjustment for other complications of prematurity, including intraventricular hemorrhage, necrotizing enterocolitis, and bronchopulmonary dysplasia, infants with late-onset sepsis had a significantly longer hospitalization (p <0.001). Moreover, neonates in whom late-onset sepsis developed were significantly more likely to die than those who were uninfected (17% vs 7%; p <0.000 1), especially if they were infected with gram-negative organisms (40%) or fungi (28%). Deaths attributed to infection increased with increasing chronologic age. Whereas only 4% of deaths in the first 3 days of life were attributed to infection, 45% of deaths after 2 weeks were related to infection. CONCLUSIONS: Late-onset sepsis is a frequent and important problem among VLBW preterm infants. Successful strategies to decrease late-onset sepsis should decrease VLBW mortality rates, shorten hospital stay, and reduce costs.

Age of Onset↗
PubMed1996

Early-onset sepsis in very low birth weight neonates: a report from the National Institute of Child Health and Human Development Neonatal Research Network.

OBJECTIVE: Early-onset sepsis (occurring within 72 hours of birth) is included in the differential diagnosis of most very low birth weight (VLBW) neonates. To determine the current incidence of early-onset sepsis, risk factors for disease, and the impact of early-onset sepsis on subsequent hospital course, we studied a cohort of 7861 VLBW neonates (401 to 1500 gm) admitted to the 12 National Institute of Child Health and Human Development (NICHD) Neonatal Research Network centers during a 32-month period (1991-1993). METHODS: The NICHD Neonatal Research Network maintains a prospectively collected registry on all VLBW neonates born or cared for at participating centers. Data from this registry were analyzed retrospectively. RESULTS: Blood culture-proven early-onset sepsis was uncommon, occurring in only 1.9% of VLBW neonates. Group B streptococcus was the most frequent pathogen associated with early-onset sepsis (31%), followed by Escherichia coli (16%) and Haemophilus influenzae (12%). Decreasing gestational age was associated with increased rates of infection. Antibiotic therapy for suspected sepsis is frequently initiated at birth in VLBW neonates. Almost half of the infants in this cohort were considered to have clinical sepsis and continued to receive antibiotics for 5 or more days, despite a negative blood culture result in 98% of cases. These findings underscore the difficulty of ruling out sepsis in the symptomatic immature neonate and the special concern for culture-negative clinical sepsis in the face of maternal antibiotic use. Neonates with early-onset sepsis were significantly more likely to have subsequent comorbidities, including severe intraventricular hemorrhage, patent ductus arteriosus, and prolonged assisted ventilation. Although 26% of VLBW neonates with early-onset sepsis died, only 4% of the 950 deaths that occurred in the first 72 hours of life were attributed to infection. For those infants discharged alive, early-onset sepsis was associated with a significantly prolonged hospital stay (86 vs 69 days; p <0.02). CONCLUSIONS: Early-onset sepsis remains an important but uncommon problem among VLBW preterm infants. Improved diagnostic strategies are needed to enable the clinician to distinguish between the infected and the uninfected VLBW neonate with symptoms and to target continued antibiotic therapy to those who are truly infected.

Age of Onset↗
PubMed1996

Interlaboratory variability of bilirubin measurements.

During an 8-month study, 14 laboratories used automated analytical systems to measure total bilirubin concentrations in lyophilized bovine specimens containing 38, 169, and 253 micromol/L bilirubin (2.2, 9.9, and 14.8 mg/dL, respectively). The measured mean +/- SD (n, range) were: 39 +/- 7 micromol/L (n = 90, 31-53) [2.3 +/- 0.4 mg/dL (1.8-3.1)]; 176 +/- 29 micromol/L (n = 89, 146-222) [10.3 +/- 1.7 mg/dL (8.5-13.0)]; and 260 +/- 43 micromol/L (n = 103, 208-316) [15.2 +/- 2.5 mg/dL (12.1-18.5)]. In comparison with target values, measurements were consistently lower at 4, higher at 6, and within +/- 4% at 4 laboratories for each of the three concentrations. The measured values for each concentration remained fairly constant during the study at each laboratory. We conclude that bilirubin measurements differed significantly from the established target values at most of the participating laboratories.

Animals↗
PubMed1996

Effects of in utero substance exposure on infant neurobehavior.

OBJECTIVE: This study had two objectives: (1) to assess infant behavior by using the NICU Network Neurobehavioral Scale (NNNS), an assessment designed specifically for prenatally drug-exposed infants; and (2) to control for the effects of polydrug use involving alcohol, marijuana, and cigarettes on the neurobehavioral status of the newborn infant. METHODS: The subjects and controls in this study were full-term infants of appropriate gestational age with no medical problems. At 1 to 2 days of age, 20 infants exposed to cocaine, alcohol, marijuana, and cigarettes; 17 infants exposed to alcohol and/or marijuana and cigarettes; and 20 drug-free infants were evaluated by using the Neonatal Intensive Care Unit Network Neurobehavioral Scale. The data were reduced to reflect clinically defined categories of neurobehavioral function and were analyzed by using analysis of variance and chi 2 statistics. RESULTS: Cocaine-exposed infants showed increased tone and motor activity, more jerky movements, startles, tremors, back arching, and signs of central nervous system and visual stress than unexposed infants. They also showed poorer visual and auditory following. There were no differences in how the examination was administered to cocaine-exposed and nonexposed infants. Reduced birth weight and length were also observed in cocaine-exposed infants. CONCLUSION: Differences attributable to cocaine-exposed infants were related to muscle tone and motor performance, following during orientation, and signs of stress. However, cocaine-exposed infants were not more difficult to test, nor did they require an alteration in the examination. Both neurobehavioral patterns of excitability and lethargy were observed. Findings may have been due to the synergistic effects of cocaine with alcohol and marijuana.

Cannabis↗
PubMed1996

Neurodevelopmental outcome at 36 months' corrected age of preterm infants in the Multicenter Indomethacin Intraventricular Hemorrhage Prevention Trial.

OBJECTIVES: Low-dose indomethacin has been shown to prevent intraventricular hemorrhage (IVH) in very low birth weight neonates, and long-term neurodevelopmental follow-up data are needed to validate this intervention. We hypothesized that the early administration of low-dose indomethacin would not be associated with adverse cognitive outcome at 36 months' corrected age (CA). METHODS: We enrolled 431 neonates of 600 to 1250 g birth weight with no IVH at 6 to 12 hours in a randomized, prospective trial to determine whether low-dose indomethacin would prevent IVH. A priori, neurodevelopmental follow-up examinations, including the Stanford-Binet Intelligence Scale and Peabody Picture Vocabulary Test-Revised, and standard neurologic examinations were planned at 36 months' CA. RESULTS: Three hundred eighty-four of the 431 infants survived (192 [92%] of 209 infants receiving indomethacin versus 192 [86%] of 222 infants receiving saline), and 343 (89%) children were examined at 36 months' CA. Thirteen (8%) of the 166 infants who received indomethacin and 14 (8%) of 167 infants receiving the placebo were found to have cerebral palsy. There were no differences in the incidence of deafness or blindness between the two groups. For the 248 English-monolingual children for whom IQ data follow, the mean gestational age was significantly younger for the infants who received indomethacin than for those who received the placebo. None of the 115 infants who received indomethacin was found to have ventriculomegaly on cranial ultrasound at term, compared with 5 of 110 infants who received the placebo. The mean +/- SD Stanford-Binet IQ score for the 126 English-monolingual children who had received indomethacin was 89.6 +/- 18.92, compared with 85.0 +/- 20.79 for the 122 English-monolingual children who had received the placebo. Although maternal education was strongly correlated with Stanford-Binet IQ at 36 months' CA, there was no difference in educational levels between mothers of the infants receiving indomethacin and the placebo. CONCLUSIONS: Indomethacin administered at 6 to 12 hours as prophylaxis against IVH in very low birth weight infants does not result in adverse cognitive or motor outcomes at 36 months' CA.

Cerebral Hemorrhage↗