NDVI predicts birth seasonality in historical Baja California Sur, Mexico: adaptive responses to arid ecosystems and the North American Monsoon.

Birth seasonality is a phenomenon whereby populations can be characterized by a single month or season in which births peak. While non-human animal research suggests that seasonal birth-pulses are related to variation in climate and local energy availability, social scientists debate the mechanisms responsible for it in humans. Here we investigate the role of precipitation, temperature, and energy availability on seasonal conception and birth pulses using a historical dataset from the Baja California peninsula - a hot, arid desert that experiences seasonal climatic fluctuations associated with the North American Monsoon. Analyses suggest that 1) local energy availability had a negative relationship with conception pulses; and 2) birth pulses had a positive relationship with local energy availability and a negative relationship with temperature. Taken together, our analyses suggest that women timed conceptions when local energy availability was lowest (challenging expectations of conception rates as simply reflecting ecological influences on female fecundity), so that children were born during the seasonal "green-up" associated with the North American Monsoon. Given our results, we speculate that birth seasonality represents a form of traditional ecological knowledge to improve neonate health and wellbeing.

High-dose phenobarbital therapy in term newborn infants with severe perinatal asphyxia: a randomized, prospective study with three-year follow-up.

OBJECTIVE: To determine whether 40 mg/kg phenobarbital given to term infants with severe asphyxia would result in a lower incidence of seizures in the newborn period and an improved neurologic outcome. METHODS: We conducted a randomized, controlled, prospective study. Entry criteria included (1) an initial arterial pH less than or equal to 7.0 with a base deficit 15 mEq/L or more, (2) Apgar score less than or equal to 3 at 5 minutes of age, or (3) failure to initiate spontaneous respiration by 10 minutes of age. Sample size was calculated to detect a 50% reduction in the incidence of neonatal seizures. RESULTS: No differences were present between treatment and control groups with respect to severity of asphyxia assessed by initial arterial pH, base excess, cerebrospinal fluid lactate dehydrogenase concentration or detection of CSF creatine kinase of its BB isoenzyme. Seizures occurred in 9 of 15 infants in the treatment group and 14 of 16 infants in the control group (p = 0.11). No adverse effects were observed from phenobarbital on heart rate, respiratory rate, blood pressure, or arterial blood gas values. Three-year follow-up revealed normal outcome in 11 of 15 infants in the treatment group and 3 of 16 in the control group (p = 0.003). CONCLUSION: Phenobarbital, when administered in a dose of 40 mg/kg intravenously over 1 hour in term, severely asphyxiated newborn infants appeared to be safe and was associated with a 27% reduction in the incidence of seizures and a significant improvement in neurologic outcome at 3 years of age.

Differentiation of segmented and band neutrophils during the early newborn period.

This prospective study evaluated the degree of inter-reader variability in the identification of segmented and band neutrophils from blood smears of full-term, healthy neonates. Wide inter-reader differences of band neutrophil identification and the immature to total neutrophil ratio were observed. Because of poor correlation between evaluators of the same blood smear, the clinical utility of the manual differential leukocyte count in the evaluation of neonates is limited.

Peripheral leukocyte count and leukocyte indexes in healthy newborn term infants.

PURPOSE: This study was designed to determine normal values for the peripheral leukocyte count and leukocyte indexes in healthy term neonates at a specific time after birth. METHODS: We prospectively enrolled 193 healthy term-gestation neonates with no identifiable perinatal risk factors for sepsis. At 4 hours of age a blood sample was collected by warmed heel stick. An automated Coulter complete blood cell count and a 100-cell manual differential leukocyte count were performed on each sample. The differential count was performed by a single hematopathologist unaware of the clinical status of each infant. Perinatal factors were identified by review of the mothers' and infants' hospital records. RESULTS: The mean ratio of immature to total neutrophils was 0.16 (SD 0.10), and the 10% to 90% range was 0.05 to 0.27. The mean leukocyte count was 24.06 x 10(9)/L (24,060/mm3), and the 10% to 90% range was 16.2 to 31.5 x 10(9)/L (16,200 to 31,500/mm3). Neutropenia, < 1.5 x 10(9)/L (1500/mm3) segmented plus band form neutrophils, was not observed. Of all the perinatal factors studied, only the duration of stage 1 labor was found to be associated with significant elevations in the leukocyte and absolute neutrophil counts. CONCLUSIONS: Previously published normal ranges for leukocyte indexes in healthy newborn infants during the early neonatal period are too restrictive; reference standards should be broadened.

Early-onset group B streptococcal sepsis: a current assessment.

Group B streptococcus (GBS) is a common cause of early-onset sepsis in neonates. The most recent reviews describing incidence, diagnosis, treatment, and outcome evaluated data on patients from the early 1980s. To obtain current information about this disease, we retrospectively evaluated data on neonates with GBS early-onset sepsis from nine hospitals in the United States between Jan. 1, 1987, and Dec. 31, 1989. There were 245 infants with GBS bacteremia identified among 61,809 live births, resulting in an incidence of 0.32%. Ninety-six infants (39%) were preterm (less than 38 weeks of gestational age). Maternal risk factors for infected preterm and term infants were similar. Antibiotics were administered during parturition in 10% of infants with bacteremia. Mothers of preterm infants received antibiotics up to 48 hours before delivery; mothers of term infants received antibiotics less than 4 hours before delivery. All preterm infants with bacteremia had symptoms; 22% of term infants with bacteremia had no symptoms. Group B streptococcal meningitis was confirmed in 6.3% of infants. Although 86% survived, GBS sepsis increased the birth weight-specific mortality rate up to eightfold in preterm infants and more than 40-fold in term infants. Although the incidence of GBS early-onset sepsis is not changing, we speculate that the improved birth weight-specific survival rate and the changing clinical presentation are due to improved intrapartum and neonatal management.

Further consideration of the clonal nature of Salmonella typhi: evaluation of molecular and clinical characteristics of strains from Indonesia and Peru.

We examined envelope protein profiles, chromosomal restriction endonuclease digest patterns, and immune responses to envelope proteins for collections of Salmonella typhi strains isolated in Peru and Indonesia. Only minor differences in envelope protein patterns were apparent among strains. Strains from 7 of 20 Indonesian patients had a distinct chromosomal digest pattern compared with patterns of Peruvian and other Indonesian strains. Strains with this pattern carried the gene for the j flagellar antigen (H1-j); differences in response to envelope proteins of j and d strains were noted on immunoblot analysis. Our data suggest that there are genotypic and phenotypic differences among S. typhi strains. The clinical importance of these differences remains to be fully evaluated; however, in this study it was not possible to show a clear correlation between strain characteristics and disease severity.

Biliary atresia registry, 1976 to 1989.

The Registry provides information about 904 children with biliary atresia from more than 100 institutions. There was a 1.4 to 1 female predominance; racial distribution was 62% caucasian, 20% black, 11% Hispanic, 4.2% asian, and 1.5% American Indian. Eight hundred sixteen (90%) underwent corrective surgery (median age at operation, 69 days). Intraoperatively, 70% had totally obliterated extrahepatic bile ducts, 22% had patency of the gallbladder and distal common duct, whereas only 8% had "correctable" biliary atresia (proximal duct patency). A variety of reconstructions were used, but the majority of patients had a Roux-en-Y portoenterostomy with or without exteriorization. Follow-up was available for 670 children (74%) with average length of follow-up of 5 years (range, 1 to 16 years). Five-year actuarial survival was 48% following Kasai's operation, but was less than 10% (at 3 years) if no operative correction was done. Survival was unaffected by sex, type of reconstruction, or cholangitis. Predictors of a bad outcome were (1) caucasian race; (2) operative age greater than 60 days; (3) presence of cirrhosis at initial biopsy; (4) totally nonpatent extrahepatic ducts; (5) absent ducts at the level of transection in the liver hilus; and (6) subsequent development of varices or ascites. Identification of factors predictive of the ultimate outcome provide a basis for either continued efforts with management of Kasai's operation or for early referral for liver transplantation.

A controlled trial of human surfactant replacement therapy for severe respiratory distress syndrome in very low birth weight infants.

In a randomized, controlled study, human surfactant derived from amniotic fluid was administered within 12 hours of birth to infants with severe respiratory distress syndrome who were born at 24 to 32 weeks of gestation weighing less than or equal to 1500 gm. A second dose of surfactant was given to patients in the treatment group if they met ventilator requirements indicating relapse or lack of response to the initial dose. No significant improvement was observed in mortality rate (9/28 vs 15/31) or incidence of bronchopulmonary dysplasia (5/28 vs 3/31) when surfactant-treated infants were compared with control subjects, although there was a significant reduction in initial respirator and inspired oxygen requirements and the arterial/alveolar oxygen ratio improved. In addition, there was a significant reduction in pulmonary air leak in treated infants (10/28 vs 20/31; p less than 0.05). Retreatment was associated with an attenuated ventilatory response and with a higher mortality rate (7/14) than that of infants who did not require a second dose (2/14; p = 0.05), indicating a more severe form of disease. Multiple discriminant analysis, including eight independent variables, revealed that increasing birth weight, earlier age at surfactant treatment, and female gender were significantly associated with survival. These data suggest that early surfactant treatment may reduce mortality rates in very low birth weight infants with severe respiratory distress syndrome, as well as reduce ventilator requirements and the incidence of pulmonary air leaks.

Lack of correlation between infection with reovirus 3 and extrahepatic biliary atresia or neonatal hepatitis.

Infection with reovirus 3 (Reo-3) has been suggested as the cause of extrahepatic biliary atresia and idiopathic neonatal hepatitis, but confirmation has been lacking. Therefore we have searched for a specific anti-Reo-3 antibody response in the sera of patients with biliary atresia or neonatal hepatitis and for Reo-3 antigens in their hepatobiliary tissues. Sera from 23 infants with extrahepatic biliary atresia, 12 with neonatal hepatitis, 30 age-matched control patients with other liver diseases, and 55 control patients without liver disease were tested by an enzyme-linked immunosorbent assay for total (IgA, IgG, and IgM) anti-Reo-3 antibodies; sera of infants younger than 6 months of age were tested also for IgM anti-Reo-3 antibodies alone. There was no difference between either total or IgM anti-Reo-3 antibody levels in infants with extrahepatic biliary atresia or neonatal hepatitis and levels in control infants. Reo-3 antigens were not detected in the hepatobiliary tissues of 19 infants (18 with biliary atresia, one with neonatal hepatitis) by an immunoperoxidase method that readily demonstrated Reo-3 in control infected HEp-G2 cells. Our data do not support a relationship between neonatal liver diseases and infection with Reo-3.

Extracellular fluid volume changes in very low birth weight infants during first 2 postnatal months.

Serial extracellular volume (ECV) changes were measured in 18 infants of less than 32 weeks gestation. Results were compared with changes in body weight, fluid and sodium intake, urine output, and serum sodium concentration. Mean +/- SD ECV decreased from 550 +/- 116 mL/kg on day 1 to 359 +/- 66 mL/kg on day 14. Thereafter, mean ECV/kg remained between 336 +/- 42 and 349 +/- 54 mL/kg. Clinical hydration and serum sodium concentration usually remained normal during this reduction of stabilization of ECV/kg. Six episodes of hyponatremia occurred at 11 to 31 days of age. Mean ECV/kg was significantly lower in infants with hyponatremia compared with infants of similar age with normal serum sodium concentration (303 +/- 36 mL/kg vs 368 +/- 56 mL/kg, P less than 0.01). Sodium intake in the two groups was similar. We conclude that ECV in the VLBW infant decreases postnatally and is regulated within a range similar to that in older infants, and that postnatal natriuresis in the first 2 weeks of life represents physiologic reduction of the expanded ECV of the fetus. Late hyponatremia may indicate excessive sodium loss and ECV depletion.

Postnatal changes in total body water and extracellular volume in the preterm infant with respiratory distress syndrome.

Body water compartment changes were assessed during postnatal weight loss in 14 infants with respiratory distress syndrome. Total body water and extracellular volume were measured by dilution methods on the first day of life and again between the third and sixth days of life. Extracellular volume changes were calculated between the first and second determinations by measurement of chloride balance. Fluid therapy was prescribed to allow negative net water balance and a 1% to 3% reduction in body weight per day. All infants had concurrent reductions in body weight, total body water, and extracellular volume. Progressive daily extracellular volume reduction concurrent with weight loss was also apparent from chloride balance data. The correlation of changes in body weight with extracellular volume in individual subjects was poor (r = 0.05). We speculate that variations between sodium and free water balance in the sick preterm infant may be responsible for variability in the distribution of postnatal body water losses. Assessment of hydration in the newborn infant should include consideration of sodium balance and alterations of serum osmolality, and changes in body weight.

Neonatal pulmonary hypoplasia with premature rupture of fetal membranes and oligohydramnios.

We assessed pulmonary function and compression deformities in 76 preterm infants less than or equal to 34 weeks gestation who had premature rupture of membranes (PROM) for longer than 5 days (mean +/- SD 18.8 +/- 15.4 days, range 6 to 90 days). Twenty-one of the 76 infants had oligohydramnios and positional deformities at birth; however, only two infants met all the criteria for the oligohydramnios tetrad. All 21 required assisted ventilation from the moment of birth. Twenty infants had clinical evidence of pulmonary hypoplasia; 18 of these died. Pulmonary hypoplasia was confirmed by significantly low wet lung weights, low lung DNA content, or low radial alveolar counts in the 13 infants with postmortem examinations. Fifty-five infants with PROM for longer than 5 days did not have positional deformities. Twenty-one required assisted ventilation, of whom 10 had severe oligohydramnios. Eleven of the 21 died; autopsies were performed. All had normal wet lung weights, but seven had significantly decreased radial alveolar counts, implying a less severe but still fatal form of pulmonary hypoplasia. None of the remaining 34 infants had lung disease, and only three had oligohydramnios. We conclude that pulmonary hypoplasia can result from PROM associated with severe oligohydramnios of as short as 6 days duration. Furthermore, fatal pulmonary hypoplasia can occur with little or no external deformation.

Barriers to medical care of Mexican-Americans: the role of social class, acculturation, and social isolation.

Literature on medical care utilization by Mexican-Americans suggests that patterns of utilization can be explained, in part, by acculturation, social class and social isolation. The relative importance of these variables is explored in a survey of a rural Mexican-American community in Southern Texas. Data on 152 families are analyzed using a logit analysis, with utilization as the outcome variable. The results suggest that acculturation has a direct effect, while social class and social isolation interact to have a weak effect independent of acculturation. These results confirm the importance of understanding all three variables in planning and implementing medical care programs in Mexican-American communities.

Etiologic factors in rickets of very low-birth-weight infants.

The incidence of rickets was found to be 32% (39/125) in a retrospective review of consecutive survivors of very low birth weight in whom serial radiographic and biochemical data were obtained. A higher proportion of these infants were black, had a greater initial weight loss, and had a longer hospitalization; there was a prevalence of births in the spring. Soy formula, supplemented with calcium and vitamin D but not phosphorus, was used predominantly in both groups; cumulative calcium, phosphorus, vitamin D, and caloric intakes were the same. We believe that the etiology of rickets in VLBW infants is multifactorial; however, nutritional deficiency is of central importance. Soy isolate formula, as well as human milk and many other commercially available formulas, do not provide sufficient calcium and phosphorus to keep pace with rates of intrauterine accretion. Supplementation with calcium, phosphorus, and vitamin D, beginning as soon as possible after birth, is indicated.