Search PubMed⌕ Search

Biomedical subjects

W Oh

Publications and source records attributed to W Oh.

At least 73 records · Page 4Linked to original sources
PubMed1995

Postnatal maturation of the blood-brain barrier for unbound bilirubin in newborn piglets.

The postnatal maturation of the blood-brain barrier (BBB) for unbound bilirubin was studied in 2-day- and 2-week-old piglets. Hyperbilirubinemia was induced by bolus infusion of bilirubin at 25 mg/kg followed by continuous infusion of 20 mg/kg/h for 3 h. During the study period, arterial blood pH and blood gas tensions, serum osmolarity, and mean arterial blood pressures were within the physiologic range. Brain bilirubin content and the brain/blood distribution ratio for bilirubin were higher in the 2-day-old than in the 2-week-old piglets. In both age groups, regional brain bilirubin concentration and brain/blood ratios were higher in subcortical regions (cerebellum and brainstem) than in the cerebral cortex. We conclude that in newborn piglets the blood-brain barrier for unbound bilirubin matures with increasing postnatal age and that irrespective of maturity the relative permeability of the BBB for bilirubin appears higher in subcortical than in cortical regions.

Aging↗
PubMed1995

Antenatal steroids, delivery mode, and intraventricular hemorrhage in preterm infants.

OBJECTIVE: The relationship between antenatal steroids, delivery mode, and early-onset intraventricular hemorrhage was examined in very-low-birth-weight infants. STUDY DESIGN: A total of 505 preterm infants (birth weight 600 to 1250 gm) were enrolled in a multicenter, prospectively randomized, controlled trial evaluating the efficacy of postnatal indomethacin to prevent intraventricular hemorrhage. All infants had echoencephalography between 5 and 11 hours of life. RESULTS: Seventy-three infants had intraventricular hemorrhage within the first 5 to 11 hours (mean age at echoencephalography 7.5 hours). Four hundred thirty-two infants did not have early intraventricular hemorrhage. There was less antenatal steroid treatment (19% vs 32%, p = 0.03) and more vaginal deliveries (71% vs 45%, p < 0.0001) in the group with early intraventricular hemorrhage. Of 152 infants who received antenatal steroids, those delivered by cesarean section had significantly less early-onset intraventricular hemorrhage than did those delivered vaginally (4% vs 17%, p = 0.02). Of the 353 not exposed to antenatal steroids, 10% of infants delivered by cesarean section and 22% delivered vaginally had early intraventricular hemorrhage (p = 0.003). CONCLUSION: These data are the first to suggest that both antenatal steroids and cesarean section delivery have an important and independent role in lowering the risk of early-onset intraventricular hemorrhage.

Cerebral Hemorrhage↗
PubMed1995

Maternal and neonatal morbidity associated with in vitro fertilization.

OBJECTIVE: The purpose of this case-control study was to examine the maternal and neonatal morbidities associated with in vitro fertilization (IVF) in a single large teaching hospital. It was hypothesized that IVF mothers would have more perinatal complications and IVF infants would have higher mortality and morbidity rates than non-IVF control subjects. METHODS: One hundred forty-three gestations resulting from 101 IVF pregnancies, which included singletons (n = 62), twins (n = 72), and triplets (n = 9), were compared with equal numbers of non-IVF control subjects. Each pregnancy was matched by maternal age, race, insurance type, neonatal gender, order of gestation, order in delivery, and date of delivery (+/- 6 months). Among the 143 matched gestations, six IVF and seven control infants died, leaving 137 IVF and 136 control neonates for comparison. RESULTS: The IVF mothers had more pregnancy-induced hypertension (21% vs 4%), premature labor (44% vs 22%), labor induction (25% vs 1%), and preterm delivery (37% vs 21%). The IVF infant survivors had a lower mean (+/- SD) birth weight (2623 +/- 857 gm vs 3006 +/- 797 gm), more frequent occurrence of low birth weight (42% vs 27%), and shorter gestations (37 +/- 4 vs 38 +/- 3 weeks). The IVF infants had longer hospitalizations, more days of oxygen therapy, more days of continuous positive airway pressure, and increased prevalence of respiratory distress syndrome, patent ductus arteriosus, and sepsis. CONCLUSIONS: Couples who undergo IVF appear to be at increased risk of having low birth weight and preterm infants, and multiple gestations account for most of the neonatal morbidities. Both the mothers who conceive multiple gestations by means of IVF and their neonates are at an increased risk of having multiple morbidities.

Adult↗
PubMed1995

Effects of maternal preeclampsia on brain-stem auditory evoked response in very low birth weight infants.

OBJECTIVE: Because stress in utero may enhance neuromotor maturation, we hypothesized that infants born to mothers with preeclampsia would have a shorter absolute latency V and interpeak latency I-V period (brain-stem conduction time) of brain-stem auditory evoked response (BAER) than infants born to normotensive mothers. STUDY DESIGN: A retrospective cohort study was performed to assess the effects of maternal preeclampsia on BAER of very low birth weight infants. The cohort consisted of 24 infants with a birth weight less than 1251 gm born to mothers with preeclampsia, and 48 infants born to normotensive mothers, matched for birth date within 2 months, gestational age, and chronologic age at the time of the BAER test. The BAER test was completed before discharge, with the infant in a quiet state and the use of a 30 dB stimulus. RESULTS: The mean latencies of wave V were shortened bilaterally (left 8.60 +/- 0.6 msec vs 9.02 +/- 0.6 msec, p < 0.008; right 8.61 +/- 0.6 msec vs 8.96 +/- 0.6 msec, p < 0.033, and the interpeak latency of I-V was significantly shortened compared with the control subjects on the left (left 4.91 +/- 0.5 msec vs 5.38 +/- 0.6 msec, p < 0.003; right 5.17 +/- 0.5 msec vs 5.37 +/- 0.6 msec, not significant). CONCLUSION: These results suggest that the intrauterine stress of maternal preeclampsia accelerates the maturation of the auditory nerve and brain-stem auditory pathway in very low birth weight infants.

Adult↗
PubMed1995

Effects of single dose calcium gluconate infusion in hypocalcemic preterm infants.

We conducted a prospective, double-blind study of 43 preterm infants to examine the effect of a single calcium gluconate infusion as therapy for neonatal hypocalcemia on serum calcium concentrations and hypocalcemic signs in preterm infants with low total serum calcium concentrations. Total and ionized serum calcium was measured and signs of irritability, jitteriness, and twitching were scored (scale 0-9) by blinded observers before and after receiving one dose of either calcium gluconate (100 mg/kg) or placebo (normal saline). Total and ionized serum calcium increased 3 to 6 hours following the calcium, but not the placebo, infusion. Of the infants with hypocalcemic signs, the average score of hypocalcemic signs decreased in the 11 calcium-treated infants; the 12 infants with hypocalcemic signs showed no change of hypocalcemic signs following treatment with placebo. We conclude from this study that a single dose of calcium gluconate (100 mg/kg) in hypocalcemic preterm infants raise total and ionized serum calcium and decrease clinical signs of hypocalcemia.

Calcium↗
PubMed1995

Effects of indomethacin on brain blood flow, cerebral metabolism, and sagittal sinus prostanoids after hypoxia.

We tested the hypotheses that during recovery from hypoxia, newborn piglets exhibit a posthypoxic cerebral hyperemia, indomethacin-pretreated piglets exhibit a posthypoxic cerebral hypoperfusion, and that the changes caused by indomethacin are dose dependent and related to the loss of prostanoids. We studied piglets exposed to 40 min of hypoxia after pretreatment with high (5 mg/kg, n = 9) or low (0.3 mg/kg, n = 8) doses of indomethacin or placebo (n = 9) and allowed to recover for 120 min. In the placebo and low-dose pretreatment groups, total and regional brain blood flow increased during hypoxia but returned to baseline 10 min after hypoxia. High-dose indomethacin pretreatment was associated with a posthypoxic hypoperfusion to certain brain regions at 10 min of recovery to values similar to those after indomethacin treatment before the onset of hypoxia. During and after hypoxia, the cerebral metabolic rate of oxygen was preserved in both the placebo and low-dose groups and decreased significantly during hypoxia in the high-dose group. Sagittal sinus prostacyclin was reduced significantly in both indomethacin-treated groups throughout the study. We conclude that a posthypoxic hyperemia is not observed in newborn piglets. This finding was not altered by pretreatment with a therapeutic dose of indomethacin, whereas a pharmacological dose was associated with selective hypoperfusion to certain brain regions both before hypoxia and during recovery from hypoxia.

Animals↗
PubMed1995

Lack of production and growth-modulating effects of 1a,25-dihydroxyvitamin D3 in cultured fetal rat hepatocytes.

1a,25-Dihydroxyvitamin D3 [1,25(OH)2D3], the hormonal form of vitamin D3, has been shown to play a role in the regulation of growth of the regenerating adult rat liver following partial hepatectomy. In addition, a recent study implicated the neonatal liver as a possible extrarenal site of 1,25(OH)2D3 synthesis. Therefore, in our present study we used rapidly growing fetal hepatocytes in culture as a model cell line for regenerating hepatocytes and tested the hypothesis that fetal hepatocytes locally produce 1,25(OH)2D3 which in turn regulates their growth. Hepatocytes isolated from 19-day rat fetuses were grown in culture for 24 h in minimal essential medium without added serum or mitogens. To identify 1,25(OH)2D3 production, we incubated fetal hepatocytes in culture with 3H-25-hydroxyvitamin D3 (3H-25-OH D3) for 2, 6 and 24 h. High-pressure liquid chromatographic analysis of the lipid extract of the medium and cells revealed no evidence of conversion of 3H-25-OH D3 into 3H-1,25(OH)2D3. Additionally, to investigate the effect of 1,25(OH)2D3 on DNA synthesis in fetal liver, we measured 3H-thymidine incorporation by the cultured fetal hepatocytes following 24 h of exposure to various concentrations of 1,25(OH)2D3. The results of DNA synthesis revealed no effect of 1,25(OH)2D3 on fetal hepatocyte growth. As alterations in growth regulation by 1,25(OH)2D3 in other cells are thought to be mediated by intracellular vitamin D receptors (VDR), the expression of the VDR message in the fetal and maternal tissues of a pregnant rat was studied. RNA was first isolated from fetal liver, fetal kidney, maternal liver and maternal kidney, and the corresponding cDNA was then generated by reverse transcription.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Developmental outcome as a function of the goodness of fit between the infant's cry characteristics and the mother's perception of her infant's cry.

OBJECTIVE: To determine whether the "goodness of fit" between infant cry characteristics and the mother's perception of the cry is related to developmental outcome at 18 months of age. DESIGN: This was a prospective, longitudinal study from birth to 18 months performed in a blinded manner. SETTING: The study was conducted in a maternity hospital, including normal and special care nurseries and a laboratory for developmental follow-up. PATIENTS: The 121 term and preterm infants and their mothers were selected to meet medical criteria. MEASUREMENT: Acoustic analysis of 1-month infant cry and the mother's perception of the same cry was used to divide subjects into four groups representing matches and mismatches between infant cry characteristics and maternal cry perception. Primary outcome measures of cognitive, language, motor, and neurologic outcome were administered at 18 months. Caretaking environment measures were also recorded. RESULTS: Statistically significant (P < .05) findings showed that matched groups scored higher on measures of language and cognitive performance than infants in the mismatch groups, with a particular advantage for infants in the matched group in which mothers accurately perceived the higher-pitched cries of their infants. There were no differences between the groups in biologic or sociodemographic factors. Group differences were observed in social support and maternal self-esteem. CONCLUSIONS: Matches and mismatches between infant cry characteristics at 1 month and the mother's perception of the cry are related to cognitive and language outcome at 18 months in term and preterm infants. This relation is probably due to transactional processes in which developmental outcome is affected by the clarity of the infants' signals and by the ability of the mother to accurately perceive her infant's signals. The mother's ability to read her infant's cues may be affected by factors such as social support and self-esteem.

Adult↗
PubMed1995

Psychological distress in mothers of preterm infants.

The purpose of this study was to identify infant and maternal characteristics that predict psychological distress among mothers of preterm infants admitted to the neonatal intensive care unit (NICU). Infant characteristics included birth weight, gestational age, and ventilatory support, and maternal characteristics included age, parity, and socioeconomic status. Mothers (n = 142) completed questionnaires including a demographic form, the Parental Stressor Scale, and the Symptom Checklist 90-R. In hierarchical regression analyses, maternal NICU-specific distress was more strongly predicted by infant characteristics [F(3,135) = 6.80, p < .05] with maternal variables covaried. Maternal general psychological distress was more strongly predicted by maternal characteristics [F(3,135) = 6.05, p < .05]) with infant variables covaried. Twenty-eight percent of mothers reported clinically significant psychological distress compared with 10% in a normative population. Psychological distress among mothers of preterm infants appears to be common and deserves clinical consideration. The use of standardized questionnaires as part of the assessment process may improve case identification and psychosocial service delivery in the NICU.

Adaptation, Psychological↗
PubMed1994

Low-dose indomethacin therapy and extension of intraventricular hemorrhage: a multicenter randomized trial.

We enrolled 61 neonates of 600 to 1250 gm birth weight with evidence of low-grade intraventricular hemorrhage at 6 to 11 hours of age in a prospective, randomized, placebo-controlled trial to test the hypothesis that indomethacin (0.1 mg/kg given intravenously at 6 to 12 postnatal hours and every 24 hours for two more doses) would prevent extension of intraventricular hemorrhage. Twenty-seven infants were assigned to receive indomethacin; 34 infants received saline placebo. There were no significant differences between the two groups in birth weight, gestational age, sex, Apgar scores, percentage of infants treated with surfactant, or distribution of hemorrhages at the time of the first cranial sonogram (echo-encephalogram). Within the first 5 days, 9 of 27 indomethacin-treated and 12 of 34 saline solution-treated infants had extension of their initial intraventricular hemorrhage (p = 1.00). Four indomethacin-treated and three saline solution-treated infants had parenchymal extension of the hemorrhage. Indomethacin was associated with closure of a patent ductus arteriosus by the fifth day of life (p = 0.003). There were no differences in adverse events attributed to indomethacin. We conclude that in very low birth weight infants with low grade intraventricular hemorrhage within the first 6 postnatal hours, prophylactic indomethacin therapy promotes closure of the patent ductus arteriosus and is not associated with adverse events, but does not affect the cascade of events leading to parenchymal involvement of intracranial hemorrhage.

Cerebral Hemorrhage↗
PubMed1994

Cardiovascular effects of hypoxia/hypercarbia and tension pneumothorax in newborn piglets.

OBJECTIVES: To test the hypothesis that, in newborn piglets, the presence of a tension pneumothorax modifies the cardiovascular responses to hypoxia/hypercarbia. DESIGN: Prospective laboratory study. SETTING: Perinatal cardiovascular research laboratory at a university school of medicine. SUBJECTS: Seven newborn piglets. INTERVENTIONS: We sequentially exposed the piglets to a baseline (control I) measure, hypoxia/hypercarbia, tension pneumothorax with normoxia/normocarbia, and tension pneumothorax with hypoxia/hypercarbia added. MEASUREMENTS AND MAIN RESULTS: Brain and systemic blood pressures and blood flow (radionuclide-microspheres) were measured. Hypoxia/hypercarbia resulted in increased brain perfusion (207 +/- 61% of control, mean +/- SEM, p < .05) and heart perfusion (176 +/- 58% of control, p < .05) and decreased gastrointestinal perfusion (-37 +/- 9% of control, p < .05). Tension pneumothorax with normoxia/normocarbia reduced the cardiac output (-70 +/- 8% of control, p < .05), which was redistributed toward the brain (p < .05) at the expense of the gastrointestinal tract (p < .05). Although this redistribution in cardiac output persisted during tension pneumothorax with hypoxia/hypercarbia added, sustained reductions in cardiac output (-57 +/- 11%, of control, p < .01) were associated with smaller increases in perfusion to brain (55 +/- 54 vs. 207 +/- 61% of control, tension pneumothorax with hypoxia/hypercarbia added, and hypoxia/hypercarbia time periods, respectively, p < .05) and heart (65 +/- 49 vs. 176 +/- 58% of control, tension pneumothorax with hypoxia/hypercarbia added, and hypoxia/hypercarbia time periods, respectively, p < .05) and larger decreases in blood flow to gastrointestinal tract, pancreas, and kidneys (p < .05) than with hypoxia/hypercarbia alone. CONCLUSIONS: Tension pneumothorax-induced reductions in cardiac output limit the hypoxia/hypercarbia-mediated increases in perfusion to brain and heart and accentuate the hypoxia/hypercarbia-related decreases in perfusion to kidneys and splanchnic organs.

Analysis of Variance↗
PubMed1994

Appropriate use of a pediatric emergency department: is the pediatrician called before the visit?

The objective of this study was to examine the appropriateness of utilization of an urban pediatric emergency department (ED) by children who had a pediatrician and factors relating to whether the pediatrician was called before an ED visit. This was done prospectively and randomly in an urban teaching hospital pediatric ED. One hundred and sixty-six patients, 18 years old and younger, who presented for nontraumatic conditions and had a pediatrician, classified as private or nonprivate, were enrolled. A questionnaire was completed and appropriateness of visit was determined using previously published criteria. No difference in appropriateness of visit was found between private and nonprivate patients (58/98, 40/68, NS). Thirty-five of 54 (65%) parents who called their pediatrician were classified as an appropriate ED visit as opposed to 62 of 112 who did not call (55%, NS). Private patients called their physicians more often then nonprivate patients (P < 0.001). Lack of access to their primary care providers was the more common reason among nonprivate patients (P < 0.05) for not calling their pediatricians. We conclude that appropriateness of pediatric ED visits is independent of type of physician. Nonprivate patients tend to consult their physician less often before ED visits because of access problems.

Child, Preschool↗
PubMed1994

Outcome of extremely low-birth-weight infants: 1980-1990.

Neonatal and follow-up data of infants from the special care nursery whose birth weights were < 750 g, born between 1980 and 1990, were reviewed. There was a 20% relative improvement in the odds of surviving the neonatal period, a 16% improvement in the odds of being discharged and a 19% improvement in the odds of surviving until 2 years of age with each consecutive year. Home oxygen use increased significantly over the study period. The neurodevelopmental outcomes of infants were similar over the 11-year period, with 53% being classified as neurologically normal, with a mean developmental index of 83 at 1 to 2 years of age. We conclude that there has been an improved survival of infants with birth weights < 750 g in our institution, and that the overall incidence of serious neurodevelopmental deficits among survivors has remained stable.

Birth Weight↗
PubMed1994

Characterization of the interaction of the glp repressor of Escherichia coli K-12 with single and tandem glp operator variants.

The glp operons of Escherichia coli are negatively controlled by the glp repressor. Comparison of the repressor-binding affinities for consensus and altered consensus operators in vivo showed that all base substitutions at positions 3, 4, 5, and 8 from the center of the palindromic operator caused a striking decrease in repressor binding. Substitutions at other positions had a severe to no effect on repressor binding, depending on the base substitution. The results obtained indicate that the repressor binds with highest affinity to operators with the half-site WATKYTCGWW, where W is A or T, K is G or T, and Y is C or T. Strong cooperative binding of the repressor to tandem operators was demonstrated in vivo. Cooperativity was maximal when two 20-bp operators were directly repeated or when 2 bp separated the two operators. Cooperativity decreased with the deletion of 2 bp or the addition of 4 bp between the individual operators. Cooperativity was eliminated with a 6-bp insertion between the operators.

Bacterial Proteins↗
PubMed1994

Semiportable electrochemical instrument for determining carbon monoxide in breath.

Measurements of carbon monoxide (CO) in breath can be used for the diagnosis of hemolytic disease. A small, semiportable, easy-to-operate CO instrument was developed at Stanford University and tested at 12 Neonatal Research Network Centers of the National Institute of Child Health and Human Development. A syringe pump delivers 7.7 mL of sample per minute through an activate carbon filter to an electrochemical (EC) sensor having a sensitivity of 0.10 +/- 0.01 V per 1 microL/L CO in air. The electronically processed sensor signal is displayed on a digital multimeter. For a typical end-tidal CO measurement, corrected for inhaled CO, three 10- to 12-mL breath and room air samples are manually or mechanically collected and analyzed. CO determination in breath samples from 108 healthy, 1-day-old infants of nonsmoking mothers compared favorably with determinations by gas chromatography (GC), 1.3 +/- 0.8 vs 1.2 +/- 0.8 (mean +/- SD), respectively, with a regression equation of EC = 0.95 GC+0.13 (r2 = 0.98). The results demonstrate that the EC-CO instrument yields results that are comparable with those obtained by the more difficult to perform GC assay.

Breath Tests↗
PubMed1994

Bilirubin production in healthy term infants as measured by carbon monoxide in breath.

To describe total bilirubin production in healthy term infants, we measured the end-tidal breath CO, corrected for ambient CO (ETCOc), with an automated sampler and electrochemical (EC) CO instrument. For infants of mothers with a negative Coombs' test, the ETCOc was 1.3 +/- 0.7 microL/L (n = 397) and the serum bilirubin on day 3 postpartum was 73 +/- 35 mg/L (n = 381). In contrast, the ETCOc for infants with ABO or Rh incompatibility, a positive direct Coombs' test, and bilirubin > 130 mg/L (n = 9) was significantly higher, 1.8 +/- 0.8 microL/L, than for those who had a positive Coombs' test result but whose bilirubin was < or = 130 mg/L (n = 12), 1.0 +/- 0.5 microL/L (P < 0.05). At 2 to 8 h postpartum seven term babies from mothers with insulin-dependent diabetes had ETCOc of 1.8 +/- 0.7 microL/L, significantly higher than that in the other term infants [1.3 +/- 0.7 microL/L (n = 390), P < 0.04]. Their bilirubin concentration at 72 +/- 12 h was also higher: 121 +/- 45 mg/L (n = 7) vs 73 +/- 34 mg/L (n = 374; P = 0.03). We conclude that ETCOc measurements may be helpful in understanding the mechanisms of jaundice in healthy term infants in a variety of conditions.

Asian↗
PubMed1994

Family-based intervention improves maternal psychological well-being and feeding interaction of preterm infants.

OBJECTIVE: To determine the efficacy of an individualized, family-based intervention with preterm infants and their families. DESIGN: Randomized, repeated measures intervention outcome study. SETTING: Level III neonatal intensive care nursery. PATIENTS: Random sample of 34 preterm infants < or = 1500 g and their families. INTERVENTIONS: Individualized, family-based intervention during the hospitalization and transition to home addressed problems identified by parents in four domains including: infant behavior and characteristics, family organization and functioning, caregiving environment, and home discharge and community resources. MEASUREMENTS AND MAIN RESULTS: Standardized questionnaires were administered at baseline and discharge to mothers, and predischarge bottle-feeding interactions were videotaped and coded by two blinded observers. Results were in favor of intervention (Int) versus control (Con) mothers (baseline; discharge) (P < .05) on the Parental Stressor Scale Sights and Sounds subscale (Int 2.4 +/- 1.0; 2.0 +/- 0.8 vs Con 2.4 +/- 0.9; 2.6 +/- 0.8); Child's Appearance and Behavior subscale (Int 2.8 +/- 1.0; 2.5 +/- 1.1 vs Con 2.8 +/- 0.8; 3.1 +/- 0.6); and Total Stressor Score (Int 93.9 +/- 36.6; 72.3 +/- 41.8 vs Con 87.5 +/- 26.7; 87.8 +/- 26.2). On the Beck Depression Inventory, intervention mothers had significant decreases in depressive symptoms (39%; 11%) vs control mothers (31%; 44%). Maternal self-esteem in both groups improved over time. There were no significant group differences in family environment. During feeding interactions, intervention infants grimaced (P < .001) and gagged (P < .05) less than controls. Intervention mothers less frequently interrupted feedings (P < .001); less frequently stimulated infant sucking (P < .01); smiled more (P < .001); vocalized more (P < .01); demonstrated greater sensitivity to infant behavior (P < .001), better quality of physical contact (P < .001), and more positive affect (P < .01). CONCLUSIONS: Individualized, family-based intervention appears to reduce maternal stress and depression, and to enhance early mother-infant feeding interactions. Further research is needed to determine whether these short-term beneficial effects persist beyond the newborn period.

Adult↗