摘要:

The fetal zone of the adrenal gland is known to persist after preterm birth, but there is uncertainty as to how long adrenal fetal zone steroid production continues and how it is regulated. The purpose of this study was to test two hypotheses. First, that the urinary excretion of 3β-OH-5-ene steroids persists until term, and then declines, as it does in full-term infants. Second, that the persistence of the fetal zone is due to continuing ACTH stimulation. A longitudinal observational study was undertaken in 22 preterm infants of 24-31-wk gestation. Sequential measurements were made of urinary 3β-OH-5-ene steroids (fetal zone steroid metabolites), plasma dehydroepiandrosterone sulfate (DHEAS), and ACTH. Excretion of urinary 3β-OH-5-ene steroids was 1500-2000 µg kg-1d-1, persisting until term, and declining abruptly at ∼42 wk postconceptional age (PCA), to levels comparable to term infants at the same PCA. Median plasma ACTH levels rose from <7.6 pg mL-1at 25-wk PCA to 34.5 pg mL-1at 46-wk PCA. Urinary 3β-OH-5-ene steroids were highest when ACTH levels were lowest, and were declining when ACTH was rising. In four infants given dexamethasone, urinary excretion of 3β-OH-5-ene steroids and plasma DHEAS were not suppressed fully, when plasma ACTH and cortisol, and urinary cortisol metabolites were. These data suggest that ACTH is not the sole regulator of the adrenal fetal zone steroid synthesis and that involution of the fetal zone is related to gestation rather than birth.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Hydrops fetalis, with or without oligo- or polyhydramnios, is associated with very high fetal mortality. In many cases the causes are unknown. Chronically cannulated ovine fetuses have been used as animal models to study the regulation of fetal fluid balance. This study reports that the mid-gestation ovine fetus (70 ± 1 d of gestation; term = 145-150 d) is susceptible to the development of fetal abnormalities (excess allantoic fluid-hydrallantois, with or without hydrops and hydranencephaly), when blood vessels in the neck are cannulated. Cannulation of one carotid artery and one jugular vein, or cannulation of a single jugular vein resulted in 5 out of 12 fetuses having abnormalities 1 wk later. In contrast, six fetuses at 115 d of gestation that had both carotids and one jugular vein ligated cranially and cannulated, developed hydranencephaly but no hydrops or hydrallantois. In the mid-gestation fetus hydrallantois [760 ± 140 mL (n= 5)versus104 ± 23 mL (n= 7 controls),p< 0.001] occurred without alterations in the plasma concentrations of ACTH, cortisol, atrial natriuretic peptide, or aldosterone, as well as without anemia. Although the causes of the fluid abnormalities were not resolved, it is important to note the developmental differences in vulnerability.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The threonine content of most of the infant formulas currently on the market is approximately 20% higher than the threonine concentration in human milk. Due to this high threonine content the plasma threonine concentrations are up to twice as high in premature infants fed these formulas than in infants fed human milk. To study the effect of different threonine intakes on plasma and tissue amino acid concentrations, 24 young male Wistar rats were fed three experimental diets based on a mixture of bovine proteins with a whey protein/casein ratio of 60/40 with different threonine contents [group A, 0.86 g of threonine/100 g (n= 8); group B, 1.03 g of threonine/100 g (n= 8); group C, 2.21 g of threonine/100 g (n= 8)]. Eight animals were fed a typical rat diet based on bovine casein as controls. After a feeding period of 15 d, amino acids were measured in plasma and in homogenates of the cerebral cortex, brain stem, liver, and muscle. There was a significant correlation between threonine intake and plasma threonine levels (r= 0.687,p< 0.001). The plasma threonine concentration correlated significantly with the threonine concentration in the cortex (r= 0.821,p< 0.01) and the brain stem (r= 0.882,p< 0.01). There was a positive significant correlation between threonine and glycine concentrations in the cortex (r= 0.673,p< 0.01), and the brain stem (r= 0.575,p< 0.01), whereas the glycine concentration decreased with increasing threonine intakes in the liver and muscle. The presented data indicate that increasing the threonine in plasma leads to increasing brain glycine and thereby affects the neurotransmitter balance in the brain. This may have consequences for brain development during early postnatal life. Therefore, excessive threonine intake during infant feeding should be avoided.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Tyrosine is considered to be an indispensable dietary amino acid in the neonate, yet achieving adequate parenteral tyrosine intake is difficult due to its poor solubility. Increasing the supply of phenylalanine is the most common means of compensating for low tyrosine levels. Unfortunately, plasma phenylalanine concentrations are sometimes elevated in infants receiving high phenylalanine intake. This led us to study the phenylalanine and tyrosine metabolism in 16 neonates randomized to receive total parenteral nutrition with either a high or a moderate phenylalanine-containing amino acid solution. A primed, 24-h continuous stable isotope infusion of L-[1-13C]phenylalanine and L-[3,3-2H2]tyrosine was given to enable the measurement of phenylalanine and tyrosine kinetics. Results demonstrated that1) phenylalanine hydroxylation was significantly greater in infants receiving high phenylalanine, 2) phenylalanine oxidation and percent dose oxidized was also significantly greater in infants receiving high phenylalanine,3) apparent phenylalanine retention was greater in neonates receiving high phenylalanine, and4) alternate catabolites of phenylalanine and tyrosine metabolism were significantly greater in infants receiving high phenylalanine compared with moderate phenylalanine. We conclude that neonates respond to increased parenteral phenylalanine intake by increasing their hydroxylation and oxidation rates. The greater oxidation of phenylalanine in infants receiving high phenylalanine in conjunction with the urinary excretion of alternate catabolites of phenylalanine and tyrosine suggests that the high phenylalanine intake may be in excess of needs. However, the lower apparent phenylalanine retention observed in infants receiving moderate phenylalanine suggests that the total aromatic amino acid level of moderate phenylalanine may be deficient for neonatal needs.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Serum concentrations of polysialylated neural cell adhesion molecule (PSA-NCAM), a developmentally regulated form of the NCAM, have been recently described to be elevated in children with rhabdomyosarcoma and neuroblastoma, proving PSA-NCAM to be a tumor marker of diagnostic relevance to these malignancies. The present investigation was undertaken to define age-dependent reference intervals in normal children. Serum concentrations of polysialylated NCAM were determined in 366 children aged newborn to 17 y and in 18 adult patients by an immunoluminescence assay using the polysialic acid-specific MAb 735. Serum levels in newborn children were 51.7 kU/L (mean ± 12.0 kU/L SD), whereas in adult patients they were 9.9 kU/L (mean ± 3.5 kU/l SD). Assigning the patients to 14 different age groups, a gradual decay of PSA-NCAM serum concentrations was observed, and therefore, mean levels and empirical interpolated percentiles were determined for every age group. Applying specially fitted logistic functions, two different sigmoid graphs were obtained describing the age-dependent decrease of serum PSA-NCAM during the neonatal period and during childhood. The age at which the levels reach half the initial value was located at 3.1 d (mean ± 2 d SE) and 14 y (mean ± 1 y SE), respectively. There was no difference between male and female individuals. Repeated measurements revealed variations below 10%. For the first time, our study describes serum levels of PSA-NCAM in children of different age and their gradual decay until adulthood.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

The relationship between the most common disease-causing mutations, the clinical manifestation, and lung function was prospectively assessed in 60 infants (33 females, 27 males) with cystic fibrosis at time of diagnosis (age: 7.2 months; range: 0.8-23.8 months). Lung function was assessed by infants wholebody plethysmography. Age at time of diagnosis was independent from the genotype. Weight gain from birth until the time of diagnosis expressed in percent predicted of a normal population was lower in the 3905insT group (57.9 ± 19.0%) compared with ΔF508 homozygotes (62.5 ± 20.6%; n.s.) and the R553X group (85.9 ± 10.9%;p< 0.005). Differences regarding lung function within the genetic groups are mainly related to pulmonary hyperinflation, measured by thoracic gas volume (TGV), present in 8 of 9 infants with 3905insT, differentiating this frameshift mutation (TGV of 7.0 ± 3.6 SD-S) from the R553X mutation (TGV 2.1 ± 4.6 SD-S;p< 0.02). It is concluded that the variable disease findings in infants with cystic fibrosis is clinically and functionally reflected by features already present at time of diagnosis. The degree of pulmonary hyperinflation is, at least partly, influenced by the genotype.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Hereditary pancreatitis (HP) is the second most common cause of chronic childhood pancreatitis in the United States. Mutations in the cationic trypsinogen gene on chromosome 7 are known to cause HP. We identified four families in West Virginia with symptoms consistent with HP. To determine whether members of these families had defects in the trypsinogen gene, we tested for linkage between the HP gene and simple tandem repeat markers on chromosome 7q and screened for a specific mutation in the cationic trypsinogen gene. Two-point linkage analysis indicated that the disease gene is closely linked to three 7q markers (D7S661, D7S2511, and D7S1805). Restriction fragment length polymorphism analysis showed that all clinically affected members and nonpenetrant carriers from the four families carried a G to A mutation in the third exon of the trypsinogen gene. These findings indicate that this mutation is the cause of HP in the families in our study. The observation that most individuals who carry the mutation have symptoms of HP is consistent with the high but incomplete penetrance of the trait. The presence of a single mutation and a common linked haplotype indicates that the defective allele arose in an ancestor common to all four families.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

We have previously shown that milk sensitization aggravates intestinal dysfunction in the malnourished guinea pigs, suggesting that it may also impair the recovery from malnutrition. To test this hypothesis, the growing guinea pigs were malnourished by feeding only maize for 7 d and then were refed for 21 d with a balanced diet containing either intact or hydrolyzed cow's milk proteins. The control animals received the hydrolyzed milk protein diet for 28 d. After an initial period of total inhibition of growth owing to maize, guinea pigs gained weight regularly, with both balanced diets, and there was no evidence of mucosal damage at the end of the refeeding period. However, refeeding with intact milk proteins induced milk sensitization, which was demonstrated on the systemic level by the presence of anti-β-lactoglubulin IgG1 antibodies, and on the local level by the intestinal anaphylaxis measured by the increase in short circuit current induced by β-lactoglobulin (16.4 ± 2.6 µA/cm2) in jejunal segments mounted in Ussing chambers. Such an immune sensitization was associated with impaired intestinal permeability, as both the ionic conductance (21.0 ± 1.6versus14.6 ± 0.7 mS/cm2) and the transepithelial fluxes of horseradish peroxidase (537 ± 203versus152 ± 28 ng/h·cm2) were significantly increased in guinea pigs refed with the intact milk proteins compared with controls. In contrast, there was no difference in intestinal permeability between controls and guinea pigs refed with the hydrolyzed milk protein diet. These data show that sensitization to cow's milk proteins can develop in guinea pigs recovering from severe malnutrition and may impair full intestinal repair.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

Eighteen-year-old adolescents with α1-antitrypsin (α1AT) deficiency have mostly normal lung function tests. We hypothesized that compensatory increases in other protease inhibitors and/or a decreased leukocyte activity might favorably affect the protease/protease-inhibitor balance in α1AT-deficient adolescents. At the age of 18 y 46 PiZZ (severe deficiency), 22 PiSZ (moderate deficiency), and 41 control subjects were studied. The plasma protease inhibitors α2-macroglobulin (α2M), α1-antichymotrypsin (Achy), and secretory leukocyte protease inhibitor (SLPI) were studied, and the protease elastase complexed with α1AT (HEAT) and neutrophil gelatinase-associated lipocalin (NGAL) as indicators of neutrophil leukocyte activity. Significantly higher concentrations of α2M were found in PiZ (p< 0.0001) and PiSZ (p< 0.0001) individuals compared with control subjects. The PiZZ and SZ adolescents had low levels of NGAL (p< 0.0001). Low levels of HEAT were found in PiZZ subjects (p< 0.0005). Higher concentrations of Achy were found in PiZZ (p< 0.04) and PiSZ (p< 0.05) individuals. Increased concentrations of α2M and Achy combined with decreased levels of HEAT and NGAL, indicating decreased leukocyte activity may, to some extent, compensate for the protease/protease inhibitor imbalance in the α1AT-deficiency state.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID

摘要:

To understand better the development of the neonatal immune system, we evaluated the role of labor length, gestational age, and mode of delivery on the expression of the neonatal neutrophil cell surface antigens CD11b, CD11c, CD15, CD33, and CD66b in premature newborns. Peripheral blood samples from 68 apparently healthy preterm infants were obtained within 12 h of birth and incubated with MAb to the CD antigens. Samples were lysed, fixed, and analyzed by flow cytometry. Multivariate analysis was used to study the simultaneous effect of the labor length and gestational age on the neonatal neutrophil cell surface antigen expression. A positive correlation was demonstrated between neutrophil antigen expression and labor length (p< 0.001-0.026) but not with the mode of delivery (p= 0.191-0.638). There was no significant correlation between expression of neutrophil antigens and gestational age at delivery (p= 0.057-0.866), except for CD15 (p= 0.010). Our results indicate labor length is a significant factor in neonatal neutrophil activation at birth. These findings are independent of gestational age in preterm newborns. Mode of delivery does not seem to influence neonatal neutrophil activation. The neutrophils of premature infants can be activated antenatally and/or during labor.

ISSN:0031-3998    

出版商:OVID    

年代:1998

数据来源: OVID