Nucleotide pool imbalance and adenosine deaminase deficiency induce alterations of N-region insertions during V(D)J recombination.

Template-independent nucleotide additions (N regions) generated at sites of V(D)J recombination by terminal deoxynucleotidyl transferase (TdT) increase the diversity of antigen receptors. Two inborn errors of purine metabolism, deficiencies of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP), result in defective lymphoid development and aberrant pools of 2'-deoxynucleotides that are substrates for TdT in lymphoid precursors. We have asked whether selective increases in dATP or dGTP pools result in altered N regions in an extrachromosomal substrate transfected into T-cell or pre-B-cell lines. Exposure of the transfected cells to 2'-deoxyadenosine and an ADA inhibitor increased the dATP pool and resulted in a marked increase in A-T insertions at recombination junctions, with an overall decreased frequency of V(D)J recombination. Sequence analysis of VH-DH-JH junctions from the IgM locus in B-cell lines from ADA-deficient patients demonstrated an increase in A-T insertions equivalent to that found in the transfected cells. In contrast, elevation of dGTP pools, as would occur in PNP deficiency, did not alter the already rich G-C content of N regions. We conclude that the frequency of V(D)J recombination and the composition of N-insertions are influenced by increases in dATP levels, potentially leading to alterations in antigen receptors and aberrant lymphoid development. Alterations in N-region insertions may contribute to the B-cell dysfunction associated with ADA deficiency.

Indoor airborne fiber levels of MMVF in residential and commercial buildings.

Man-made vitreous fibers (MMVF) have been used widely in commercial and residential buildings for over 50 years. Concerns have been expressed since the late 1960s that MMVF products may erode and contribute to fiber levels in the indoor environment. This cooperative investigation was undertaken to quantify indoor respirable fiber levels by phase contrast optical microscopy (PCOM) and to differentiate between fiber types using scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDX). A total of 205 stationary samples were collected using standard industrial hygiene methods in 51 residential and commercial buildings. Twenty-one simultaneous outdoor samples were collected at 19 buildings. All samples were analyzed by PCOM following the NIOSH 7400 Fiber method, "B" counting rules, and 50 randomly selected samples were analyzed by SEM-EDX. The PCOM mean value for all respirable fiber levels was 0.008 f/cc with a median value of 0.007 f/cc and a maximum value of 0.029 f/cc. Ninety-seven percent of the respirable fibers identified by SEM-EDX were determined to be organic. MMVF were detected on only two samples. Airborne fiber levels were very low and the respirable fibers present were primarily organic. The inorganic fiber levels determined by SEM-EDX which included MMVF were less than 0.0001 f/cc.

Variability of plasma cortisol levels in extremely low birth weight infants.

Cortisol is secreted by children and adults in a pulsatile pattern of 15-30 peaks and nadirs each day with a circadian rhythm. Newborns are known to lack the circadian pattern, leading to uncertainty about the appropriate time for blood sampling for assessment of adrenal function. Because extremely low birth weight (ELBW) infants may manifest signs of adrenal insufficiency, knowledge of the pattern of cortisol levels is necessary to guide the appropriate timing of blood sampling. To define the pattern of plasma cortisol levels in 14 ELBW infants, we obtained blood specimens every 20 min over a 6-h period at 4-6 days of life. Although cortisol levels in the 14 infants ranged from 2.0-54.5 micrograms/dL, each infant's cortisol levels varied little from his or her own mean cortisol level. The SDs calculated from each infant's mean cortisol level were small, ranging from 0.37-4.12 micrograms/dL. Cluster analysis was applied to the data; only 0.6 cortisol pulses/infant 6-h period were detected. Each infant's plasma cortisol levels were plotted against time, and regression analysis was performed. The slopes of the resulting lines of regression ranged from -0.0284 to 0.0221. Our data indicate that ELBW infants show little variability in their plasma cortisol levels over time; therefore, a single random measurement provides an adequate reflection of the adrenal status of the ELBW infant.

Corticosteroid binding globulin, total serum cortisol, and stress in extremely low-birth-weight infants.

Our objective was to determine if low levels of corticosteroid binding globulin (CBG) might explain the low serum total cortisol levels found in some extremely low-birth-weight (ELBW) infants. In a prospective study, serum total cortisol and CBG were measured in single blood samples from 31 ELBW infants, with a gestational age less than 28 weeks, in the first 8 days of life. Severity of illness was assessed using the Score for Neonatal Acute Physiology Perinatal Extension (SNAP-PE). The mean serum total cortisol (mean +/- 1 SD) was 9.2 +/- 9.8 mcg/mL and the mean CBG level was 1.4 +/- 0.31 mg/dL. There was no significant correlation between serum total cortisol and CBG levels (r = -0.18), severity of illness as measured by the SNAP-PE (r = +0.12), or birth weight (r = -0.12). Five of 31 infants, having a mean SNAP-PE score of 41, had serum total cortisol levels < or = 3.0 mcg/dL. Estimated mean serum free cortisol concentrations in these five infants (0.76 mcg/dL) were comparable to estimated free cortisol levels diagnostic of adrenal insufficiency in sick adult patients. Our findings indicate that CBG levels are lower in ELBW infants than in term infants, but low CBG levels do not explain the low serum total cortisol levels found in some very sick infants. Low cortisol levels in small premature infants may be adequate to support growth if the infant is well, but may result in a syndrome of adrenal insufficiency in those with severe illnesses.

Subgaleal hematoma: the need for increased awareness of risk.

Subgaleal hematoma, also known as subaponeurotic hemorrhage, is a serious complication of birth that is associated with vacuum-assisted delivery. Despite a high rate of mortality associated with subgaleal hematoma, it has received relatively little attention in the medical literature. Lack of awareness may lead to delayed diagnosis and serious consequences for infants. This paper is a report of six cases and a literature review. Prevention and early recognition and treatment of the condition can occur only with increased practitioner awareness of this entity.

A scoring system for evaluating the condition of transported neonates.

A scoring system for the evaluation of the clinical status of transported small premature infants was modified to make it applicable to the evaluation of both premature and term infants. Blood glucose concentration, systolic blood pressure, blood pH and PO2, and body temperature were assessed and given scores of 0, 1 or 2 for abnormal, borderline and normal values, respectively. The scoring system was used for quality assurance studies of changes in patient status during transport from community hospitals to the neonatal intensive care unit and proved useful in identifying inadequate attention to body-temperature maintenance. The scoring system showed an improvement in the criterion after changes in clinical monitoring and management of body temperature were instituted. An additional use of the scoring system was for the identification of specific problems in neonatal stabilization in referring community hospitals.

Hypothalamic pituitary adrenal function in the extremely low birth weight infant.

Extremely premature infants manifest clinical features suggestive of adrenal insufficiency. Yet, serum cortisol levels are similar in ill and well preterm infants in a setting where one would expect high stress levels in the ill infants. We investigated the hypothalamic-pituitary-adrenal axis in 17 extremely low birth weight stressed premature infants, mean birth weight 739 g, gestational age, 26.1 weeks, using ovine CRH (oCRH) and ACTH stimulation. oCRH (1 microgram/kg) was administered at 2-7 days of life (mean = 4.1). ACTH rose from a basal value 6.0 +/- 0.8 pmol/L (mean +/- SEM) to 9.6 +/- 1.8 pmol/L (P < 0.01) at 15 min and 9.5 +/- 1.7 pmol/L (P < 0.01) at 60 min. Basal cortisol rose from 349.3 +/- 58.1 nmol/L to 422.3 +/- 57.9 nmol/L (P < 0.01) at 15 min and 568.7 +/- 60.2 nmol/L (P < 0.01) at 60 min. Cortisol values remained significantly (P < 0.05) elevated 24 h after oCRH. An ACTH stimulation test performed 24 h after the oCRH test demonstrated a significant cortisol rise from 603.5 +/- 130.5 nmol/L to 882.7 +/- 136.6 nmol/L (P < 0.05) at 60 min. Plasma CRH immunoactivity was also measured before oCRH testing and was detectable in 10 of 15 infants. The mean CRH immunoactivity was 21.8 +/- 4.4 pmol/L in the infants, significantly higher than 8 adult male controls (P < 0.04). Our results show a normal pituitary response to ovine CRH and a normal adrenal response to ACTH. We hypothesize that cortisol levels are inappropriately low in some ill preterm infants because of the inability of the extremely premature brain to recognize the stress of the illness or because of inadequate hypothalamic secretion of CRH. The significance of the measurable plasma CRH in the first week of life is unknown.

Nutritional balance studies of VLBW infants fed their mothers' milk fortified with a liquid human milk fortifier.

This article reports the results of a study designed to compare human milk fortified with a liquid human milk fortifier to a preterm infant formula by analyzing the metabolic balances of certain nutrients when these milks are fed to premature infants. Ten very low birth weight (VLBW) infants were studied during 4-day equilibration periods, then 4-day metabolic balances of N, fat, Ca and P, while each consumed a 1:1 mixture of a pool of its own mother's milk and the liquid human milk fortifier (HM/LF). For comparison, another 10 VLBW infants were studied in similar fashion while consuming the preterm infant formula (PF). Percent nitrogen retentions were 77 +/- 4% (+SD) and 79 +/- 4%, and fat absorptions were 94 +/- 7% and 92 +/- 5% in the HM/LF and PF groups, respectively, and did not differ between the groups. Calcium retention was 86 +/- 21 mg/kg/day (51 +/- 12%) in the HM/LF group and 104 +/- 43 mg/kg/day (45 +/- 19%) in the PF group. The percent Ca retentions did not differ. Phosphorus retentions were 56 +/- 7 mg/kg/day (67 +/- 9%) and 77 +/- 18 mg/kg/day (61 +/- 14%) in the HM/LF and PF groups, respectively. Increases in weight, length, and occipitofrontal circumference (OFC) were similar and normal in both groups. We conclude that VLBW infants fed the HM/LF, mixed 1:1 with their mothers' milk, had rates of absorption and retention of Ca, P, N, and fat similar to rates found in the concurrent study of VLBW infants fed a commercially available PF.

Insulin infusion with parenteral nutrition in extremely low birth weight infants with hyperglycemia.

From Nov. 7, 1983, to Nov. 6, 1986, all infants with birth weight less than or equal to 1000 gm admitted to Oregon Health Sciences University who had persistent hyperglycemia and glycosuria were treated with graded insulin infusion while energy intake was increased to at least 100 kcal/kg/day (419 kilojoules/kg/day). The records of these infants were reviewed to define the clinical characteristics of infants likely to develop hyperglycemia and to see whether insulin administration would allow goals for energy intake to be met. There were 76 surviving infants; 34 received insulin and 42 did not. Treated infants were smaller (767 +/- 161 vs 872 +/- 98 gm; p = 0.0004), were more immature (26.8 +/- 1.4 vs 27.7 +/- 2.0 weeks; p = 0.0115), and required mechanical ventilation longer (28 +/- 19 vs 17 +/- 15 days; p = 0.0196). There were no significant differences between the groups at 3, 7, 10, or 14 days for intravenously administered glucose or for total nonprotein energy intake at 3, 7, 10, 14, 28, or 56 days. Treated infants achieved an intake of 100 kcal/kg/day (419 kilojoules/kg/day) at 15 +/- 8 vs 17 +/- 11 days and regained birth weight at 12 +/- 6 vs 13 +/- 6 days (NS). There was no difference in percent change from birth weight at 7, 14, 28, or 56 days. Treated infants had a glucose concentration of 195 +/- 60 mg/dl (10.8 +/- 3.3 mmol/L) while receiving 7.9 +/- 3.0 mg/kg/min (43 +/- 17 mumol/kg/min) of glucose at the start of insulin infusion on days 1 to 14. Insulin was given for 1 to 58 days. The initial dose was 40 to 100 mU/gm of dextrose infused (57 to 142 nmol/mol) and then gradually decreased. Less than 0.5% of blood glucose values were 25 to 40 mg/dl (1.4 to 2.2 mmol/L). We conclude that insulin infusion improves glucose tolerance in extremely low birth weight infants and allows hyperglycemic infants to achieve adequate energy intake similar to that of infants who do not become hyperglycemic.

Plasmid DNA analysis of Staphylococcus epidermidis isolated from blood and colonization cultures in very low birth weight neonates.

We prospectively studied the course of colonization and sepsis with Staphylococcus epidermidis among 29 very low birth weight neonates undergoing prolonged umbilical catheterization. S. epidermidis bacteremia occurred in 7 patients. In 6 bacteremia was preceded by positive colonization cultures. Isolates obtained from nares, base of umbilicus, umbilical catheter entry sites, catheter tips and blood were examined for plasmid DNA profiles. In 4 patients the plasmid profiles of the catheter entry site isolates were identical with those of the blood isolates. In the other 3 bacteremic patients plasmid profiles of the catheter entry site and blood isolates were different. No correlation was observed in the plasmid DNA patterns of isolates obtained from catheter tip cultures as compared to the corresponding blood cultures. The blood isolates from bacteremic patients had different plasmid profiles.

Relationship of antioxidant enzymes to trace metals in premature infants.

Serum levels of the trace metals copper, zinc, and selenium were measured in premature infants. White blood cell glutathione peroxidase and superoxide dismutase levels were measured in conjunction with the trace metals. Three groups of infants were evaluated: group I was relatively healthy, group II were infants with stage 2 bronchopulmonary dysplasia (BPD) or less, group III were infants with stage 3 BPD or worse. Zinc and selenium levels declined in all groups during conventional parenteral nutrition (TPN) regimens, while copper remained stable. Copper did decline in groups I and II coincident with an acceleration in growth rate. An expected rise in antioxidant enzyme levels in infants with pulmonary oxygen toxicity was not seen. This study suggests that supplemental selenium as well as an increased zinc intake over current recommendations for premature infants receiving TPN may be indicated.

Modified lamellar body phospholipid assay compared with L/S ratio and phosphatidylglycerol assay for assessment of fetal pulmonary status.

We used a modified lamellar body phospholipid (LB-PL) assay to evaluate the effect of sample processing and to evaluate the clinical efficacy of LB-PL determinations. Within-run and between-run CVs for the modified LB-PL assay respectively ranged from 2.9 to 6.7% and from 3.4 to 14.3%. Freezing and storage at -20 degrees C did not affect results for LB-PL (n = 12). Statistically significant amounts of lamellar bodies were lost on centrifugation, ranging from 20% at 150 X g to 54% at 1000 X g for 5 min. The LB-PL content, lecithin/sphingomyelin ratio, and phosphatidylglycerol content of 194 samples of amniotic fluid obtained within three days of delivery were compared for the assessment of fetal pulmonary maturity. Twenty-three neonates developed respiratory problems at or shortly after birth. With uncontaminated samples (n = 160), the LB-PL assay exhibited better specificity than the lecithin/sphingomyelin ratio (p less than 0.01, Chi square) or the phosphatidylglycerol assay (p less than 0.001, Chi square) for samples obtained after 36 weeks of gestation. Assay sensitivities did not differ significantly. Differences among assay predictive values were not significant.

Central venous silicone elastomer catheter placement by basilic vein cutdown in neonates.

There is a need for central venous access in small premature infants and other neonates when enteral feeding is not tolerated or is contraindicated. We placed 83 small (0.635-mm od) silicone elastomer catheters by basilic vein cutdown through a subcutaneous tunnel in 79 patients during a 12-month period. Thirty-five patients (44%) weighed less than 1,000 g. Each patient on whom the procedure was attempted had successful placement of a catheter, and they remained in place a mean of 20 days (range three to 82). Patients had a mean weight gain of 15 g per day of catheter use. Sixty-two catheters (75%) were removed electively, 13 (16%) secondary to complications, six (7%) because of patient deaths (none catheter related), and two (2%) were accidentally dislodged. Two episodes of catheter-related sepsis (0.12 episodes per 100 days of catheter use) caused by Candida albicans and Staphylococcus epidermidis were encountered. Other complications included one subclavian vein thrombosis, eight catheter occlusions, and two local arm inflammations. This technique proved to be a safe, easy, and inexpensive method to administer parenteral nutrition to neonates, especially those weighing less than 1,000 g.

Nutritional balance studies in very-low-birth-weight infants: role of whey formula.

Although the optimal type and amount of protein for feeding very-low-birth-weight (VLBW) infants is not well defined, a protein composition with a whey protein to casein ratio of 60/40 is generally considered desirable. This study used the metabolic balance technique to compare nitrogen retention rates in 19 VLBW (less than 1,530 g) infants fed either an experimental whey protein-predominant formula (WPF) containing ultra filtered whey protein or a conventional casein-predominant formula (CPF) containing approximately 20% more protein and more minerals. Blood chemistries and anthropometric measurements were assessed serially. Although infants fed CPF received and retained more protein than infants fed WPF, nitrogen retentions were 73.1 and 74.5% of intake, respectively, and not different between the two feeding groups. The data suggest that proteins from either WPF or CPF are adequately utilized by VLBW infants. Although WPF permitted nitrogen retention rates similar to fetal accretion rates, CPF more nearly met estimated nitrogen requirements of the low-birth-weight infant. Infants fed WPF showed a more favorable course with respect to their metabolic acid-base status, characterized by normal buffer base concentrations and less predisposition to metabolic acidosis. We conclude that whey-predominant protein is preferable to casein-predominant protein in the diet of VLBW neonates because it may lessen the risk of metabolic acidosis and its potential adverse effects.

Benzyl alcohol toxicity: impact on neurologic handicaps among surviving very low birth weight infants.

Benzyl alcohol preservative in solutions used to flush intravascular catheters has been linked with increased mortality and incidence of intraventricular hemorrhage in small preterm infants. This study evaluated the outcome of surviving very low birth weight infants exposed to benzyl alcohol while in our neonatal intensive care unit. Surviving infants, less than 1,250 g birth weight, admitted during the 12 months prior to discontinuation of benzyl alcohol (period I), were compared with those infants admitted during the 12 months after discontinuation of benzyl alcohol (period II). Survivors were enrolled in a follow-up program. Results of the study demonstrated that infants from period II had fewer neurologic handicaps. The incidence of cerebral palsy decreased from 50% to 2.4% (P less than .001), and the presence of cerebral palsy and developmental delay combined decreased from 53.9% to 11.9% (P less than .001). Several factors other than benzyl alcohol exposure were examined for their importance on outcome but were found not to be related to it. It is concluded that the dramatic improvement in outcome could be the result of discontinuation of benzyl alcohol.

Benzyl alcohol toxicity: impact on mortality and intraventricular hemorrhage among very low birth weight infants.

Benzyl alcohol preservative in intravascular flush solutions has been reported to cause neurologic deterioration and death in very low birth weight infants. Following the widespread discontinuation of the use of such solutions in newborns, scattered reports of decreased mortality and decreased incidence of intraventricular hemorrhage among small premature infants appeared in the pediatric literature. To better assess the true impact of benzyl alcohol toxicity in this group of infants, we undertook a detailed review of the medical records of all babies less than 1,250 g birth weight admitted to our neonatal intensive care unit for 13 months before and 13 months after the use of solutions containing benzyl alcohol was stopped. Significant decreases were found in both mortality rate (from 80.7% to 45.7%) and incidence of grade III/IV intraventricular hemorrhage (from 46% to 19%) among infants less than 1,000 g birth weight who did not receive the preservative compared with those who did. No significant changes were found in several other prenatal factors that could have contributed to this improvement in survival. We conclude that benzyl alcohol toxicity contributed significantly to both mortality and the occurrence of major intraventricular hemorrhage among infants weighing less than 1,000 g at birth and that solutions containing benzyl alcohol should never again be used in the care of such infants.

Feto-placental steroid metabolism in growth retarded human fetuses.

The goal of the study was the determination of the relative roles of the placenta and the fetus in causing low serum estriol (E3) levels in women bearing fetuses with intrauterine growth retardation (IUGR). Umbilical venous levels of E3 and dehydroepiandrosterone sulfate (DHAS) were measured in 31 samples from fetuses with IUGR, 21 of whom were vaginally delivered and 10 who were delivered by cesarean section. In addition, estrone (E1) and estradiol (E2) were measured in 11 of the samples. The results were compared with 11 samples from cesarean section delivered control term infants and 54 samples from vaginally delivered control infants. The vaginally delivered IUGR group had a significantly lower mean umbilical venous DHAS level than did their control group (2128 +/- 158 ng/ml SEM versus 2645 +/- 130, p less than 0.05). Both the vaginally delivered and cesarean section delivered IUGR infants had umbilical venous E3 levels significantly lower than in their control groups (70 +/- 10 ng/ml SEM versus 144 +/- 10, p less than 0.001, and 46 +/- 11 ng/ml SEM versus 136 +/- 23, p less than .01, respectively). Umbilical venous E1 and E2 levels were not different from the control values. E1, E2, E3, and DHAS were measured in eight maternal venous samples obtained from mothers bearing fetuses with IUGR. In comparison with 11 control mothers, only E3 was significantly different (10.7 +/- 3.0 ng/ml SEM in mothers with IUGR fetuses versus 25.0 +/- 4.9 in control mothers p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)