摘要:

Because glutamine is thought to be a major fuel for developing gut, we tested the hypothesis that extensive small-bowel resection alters whole-body glutamine metabolism in vivo. Eleven infants and children who had undergone extensive small intestinal resection (residual bowel length: 35 ± 13 cm; mean ± SD) and four control infants received 4-h primed, continuous i.v. infusions of l-[1-13C]leucine and L-[2-15N]glutamine in the postabsorptive state. The appearance rates of glutamine and leucine into plasma were determined from stable isotope enrichments in plasma at steady state. We observed the following: 1) Regardless of intestinal status, leucine and glutamine fluxes were higher in infants than values previously reported for adults. 2) Small-bowel resection was associated with a reduction in glutamine appearance rate (568 ± 124 μmol kg lean body mass-1h-1in short-bowel syndrome infants versus 816 ± 149 μmol kg lean body mass-1 h-1 in control infants; p < 0.05). 3) In contrast, leucine appearance rate was unaltered in short-bowel syndrome patients. The findings suggest that the small intestine plays a prominent role in glutamine metabolism in human infants.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Behavioral and physiologic responsivity to nasogastric gavage feeding was assessed in 36 preterm infants on 2 consecutive d. On one of these days, a pacifier was provided during and after the gavage segment of the standardized protocol. The protocol was divided into segments that included baseline, preparatory handling, pregavagc, gavage, and postgavage periods. Patterns of cardiac (heart period and vagal tone), oxygen saturation, behavioral state, and defensive behavioral responses to gavage were quantified. These stable preterm infants responded to handling and gavage feeding with reductions in heart period, vagal tone, and oxygen saturation. These responses were not altered by provision of a pacifier, although there was a tendency for fewer episodes of bradycardia and oxygen desaturation. Conversely, behavioral state was affected significantly by nonnutritive sucking: when provided with a pacifier, infants exhibited less behavioral distress, spent less time in fussy and active awake states during and after feeding, and returned to a sleep state significantly faster. There is converging evidence to suggest that nonnutritive sucking lessens behavioral distress to iatrogenic stressors but does not alter physiologic responsiveness.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

We compared the responses of ACTH and Cortisol (F) to corticotropin-releasing hormone (CRH) administration (ovine 1 μg/kg i.v. bolus) with the responses of urinary 17-OH corticosteroids (I7-OHCS) and serum deoxycorticosterone (DOC) to metyrapone administration (450 mg/ m2/dose every 4 h ± seven doses) in 16 hypopituitary patients. Glucocorticoid therapy for these patients was withheld for a minimum of 3 wk before testing. The CRH test was performed 3 d before or 3 wk after the metyrapone test was used to diagnose the ACTH reserve status. In nine ACTH-intact hypopituitary patients (post-metyrapone 17-OHCS > 12.2 (μmol/m2/d; DOC > 11.5 nmol/L), the peak F (497–773 nmol/L) and ACTH (5.2–22 pmol/L) responses to CRH stimulation were similar to those of normal subjects (F peak = 554–993 nmol/L and ACTH peak = 6–25 pmol/L at 15–60 min). In one patient with partial ACTH deficiency (postmetyrapone 17-OHCS = 10.5 μmol/m2/d; DOC = 6 nmol/L), the peak F response was low and delayed (246 nmol/L at 180 min) and the peak ACTH response was normal (7 pmol/L). Six severely ACTH-deficient patients (postmetyrapone 17-OHCS < 5.4 μLmol/m2/d; DOC ± 3.4 nmol/L) had a low F response at 15–90 min in all, with a delayed rise in three at 120–180 min in response to CRH administration, whereas ACTH responses were variable: absent or low, normal, delayed, or persistently exaggerated. In conclusion, the CRH-stimulated F response pattern in hypopituitary patients was comparable to the urinary 17-OHCS and serum DOC response to metyrapone administration. Thus, F response pattern to CRH was useful in the evaluation of ACTH reserve in hypopituitary patients. ACTH response to CRH in ACTH-deficient patients was not consistently useful for ACTH reserve evaluation because of the variable response possibly resulting from a different etiology (hypothalamus versus pituitary) of ACTH deficiency.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

To study the feasibility of noninvasive sampling in pediatric patients, we examined the concentrations of LH and FSH in paired serum and urine samples from 65 children (age 0–15 y) with highly sensitive time-resolved immunofluorometric assays. The detection limits of the assays were 0.015 lU/L for LH and 0.018 lU/L for FSH. These sensitivity levels allowed quantification of the low prepubertal LH and FSH concentrations. The correlation between serum and urine gonadotropin values was very good (r = 0.751, p < 0.001 for FSH; and r = 0.720, p < 0.001 for LH), and the urine and serum concentrations were very similar. Correction of urinary gonadotropin concentrations for changes in urinary flow by standard methods using density [concentration ± (0.02/density - 1)] or creatinine (concentration/creatinine) did not improve the correlation. Therefore, measurement of urinary gonadotropins without correction can simply be used in the pediatric outpatient setting as a noninvasive alternative to serum determinations.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Androgen insensitivity syndrome (AIS) is an X-linked disorder in which defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. This survey reports the analysis of 11 AIS subjects. The androgen receptor gene of these subjects was analyzed using polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis and sequencing or sequencing of PCR-amplified androgen receptor gene fragments alone. In total, 10 single base changes and one partial gene deletion were detected. Seven single base changes resulted in an amino acid change, one resulted in the introduction of a premature stop codon, one event represented a single base insertion resulting in a frame-shift, and one single base change affected a donor splice site. The androgen receptor protein in genital skin fibroblasts from several patients was studied with respect to molecular mass after immunoprecipitation and SDS-PAGE. Two patients expressed a truncated receptor protein in agreement with the established genomic mutation. Pedigree analysis was performed to identify possible carriers for the syndrome in families of AIS patients using single-strand conformation polymorphism and restriction site analysis of PCR products. In one case, the polymorphic (CAG)n(CAA) repeat in exon 1 encoding a polyglutamine stretch was used to identify the mutant allele in a family with X-linked partial androgen insensitivity before the identification of the actual genomic mutation. PCR-single-strand conformation polymorphism analysis proved to be a fast and reliable technique to screen for androgen receptor gene mutations and to study the androgen receptor gene of family members of AlS-affected individuals.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

An important feature of the role of IgA in protection against infection and disease at the level of the mucosal surfaces might be the elimination of pathogens without induction of a strong inflammatory reaction. In the present study we addressed the question whether IgA has a regulatory effect on the generation of reactive oxygen intermediates in human neutrophils and monocytes (i.e. the respiratory burst). Cells were stimulated with heat-inactivatedHaemophilus influenzaetype b or phorbol myristate acetate, stimuli known to use different recognition structures or signal transduction pathways. Concentrations of IgA as low as 10 mg/L significantly inhibited the receptor-dependentHaemophilus influenzae-induced respiratory burst in granulocytes, as assessed by measuring luminol-enhanced chemiluminescence. Furthermore, IgA had a dose-dependent inhibitory effect on the receptor-independent induction of the respiratory burst, as examined by flow cytometry in monocytes and granulocytes activated with phorbol myristate acetate. Our results therefore indicate that inhibition of receptor-ligand interaction is not a sufficient explanation for the IgA-mediated modulation of the respiratory burst in human phagocytic cells. In addition, IgA might directly regulate the activation of the respiratory burst at the level or downstream of protein kinase C activation. By modulating the release of mediators of inflammation such as reactive oxygen intermediates, the inflammatory response could be down-regulated at the level of the mucosal surfaces, thereby preventing the development of sequelae of an exaggerated inflammatory response potentially leading to local or systemic pathology.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Although considerable evidence suggests that bronchopulmonary dysplasia (BPD) is the result of prolonged inflammation and impaired healing of the immature lung, the mediators that regulate inflammation in neonatal lung injury have not been completely elucidated. We examined whether the cytokines IL-6 and tumor necrosis factor-α (TNF) interact to modulate a cascade of cell-cell signaling events involved in inflammation contributing to the development of BPD. To determine the relative activities of these cytokines in neonatal lung injury, lung lavage samples were serially obtained from 1 to 28 d from 11 infants with self-limited respiratory distress syndrome (RDS), 19 infants with evolving BPD, and 10 control infants ventilated for nonpulmonary reasons. On the first day of life, there were no differences in antigenic IL-6 concentrations in lavage fluids among the BPD, RDS, and control groups, but IL-6 activity determined by the 7TD1 proliferation assay was 15-fold and 6.6-fold higher in lung lavage of infants who developed BPD compared with activities in lavage from control and RDS infants, respectively (control, 49.4 ± 17.6; RDS, 117.3 ± 59.6; BPD, 779.5 ± 212.6 ± 103hybridoma units/L, mean ± SEM, p = 0.02). This suggests that pathways for inactivating or inhibiting IL-6 that may be present in the lungs of RDS and control infants may be deficient in BPD infants. IL-6 activity remained elevated in lavage of BPD infants for the first 2 wk and declined to low levels by d 28. There were no differences among groups on the first day of life for TNF antigen concentration or TNF activity determined by the L929 bioassay. Detectable but low TNF activity was found in BPD samples, with peak activity found in d-14 samples. Differences in complex interactions among these and other cytokines with their receptors and inhibitors may predispose some infants with RDS to develop BPD.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Increased fetal Hb (HbF) synthesis has been shown to occur during fetal hypoxemia and severe anemia. To determine whether increased HbF synthesis occurs during anemia of prematurity, the levels of HbF synthesis were correlated with the degree of anemia and plasma erythropoietin levels. Thirteen newborn infants born at 29.2 ± 1.7 wk of gestation were studied at a postconceptional age 36.0 ± 1.1 wk. Hb levels ranged from 65 to 78 g/L. Blood samples were incubated in an amino acid mixture containing [3H]leucine and chromatographed allowing the separation and quantitation of the α, β, and ν (AνT,GνAνI) chains. Erythropoietin was determined by RIA. The mean HbF synthesis was 77.9 ± 8.9% of total Hb synthesis (range: 61 to 91%). Plasma erythropoietin concentrations were 21.4 ± 6.4 mU/mL. There was no correlation between the total Hb or HbF synthesis and the level of erythropoietin. There was, however, a significant inverse correlation between the Hb level and HbF synthesis (p < 0.01). Nine infants who had received transfusions during the first few days of life had a mean HbF that was 53.5 ± 15.2% of total Hb, whereas their HbF synthesis was 78.4 ± 7.6%. Four of the infants never received transfusions; the total circulating HbF and HbF synthesis in these infants were 87.7 ± 7.7% and 76.8 ± 12.7%, respectively. This study shows that there can be a reactivation of HbF synthesis during severe anemia of prematurity.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Fibrinolytic parameters and von Willebrand factor (vWF) antigen were measured in the plasma of 10 patients with hemolytic uremic syndrome (HUS). Samples were taken at presentation and again 2 wk later, before and after infusion of l-desamino-8-arginine vasopressin. Compared with the plasma values of healthy control children, levels of tissue-plasminogen activator (t-PA) antigen, plasminogen activator inhibitor type I (PAI-1) activity, and vWF as well as fibrin(ogen) degradation products were significantly elevated in the plasma of HUS patients on admission. No response of the fibrinolytic parameters and vWF were seen when l-desamino-8-arginine vasopressin infusion was given on admission. After 2 wk, t-PA antigen and vWF had partially returned to basal values, and t-PA antigen increased rapidly again after l-desamino-8-arginine vasopressin infusion. To investigate whether verocytotoxin contributes to the alteration of the fibrinolytic system found in HUS patients, purified verocytotoxin-1 (VT-1) was added to the media of cultured human endothelial cells. Addition of VT-1 alone did not change the production of t-PA, plasminogen activator inhibitor type I, and vWF antigen in these cells. However, when the endothelial cells were preincubated with tumor necrosis factor-a to increase the number of VT-1 receptors, VT-1 induced a marked decrease of the synthesis of t-PA, plasminogen activator inhibitor type I, and vWF. This was caused by a decrease in overall protein synthesis in the tumor necrosis factor-α-and VT-1-treated endothelial cells. We conclude from this study that the systemic fibrinolytic parameters measured in the plasma of HUS patients are probably not a direct effect of VT-1 on the endothelium but are sequelae of the disease in which the intestine and the kidney are predominantly affected.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID

摘要:

Spinal muscular atrophy (SMA) is the second most common neuromuscular disease of childhood. It is the most common fatal recessive neuromuscular disease. This study is the first to evaluate the craniofacial growth of SMA patients. The results pertain to a sample of 25 SMA patients, between 5 and 32 y of age, who were case matched with unaffected normal controls. Group differences for 25 measures, derived from tracings of standardized cephalometric radiographs, were evaluated using multivariate analysis of variance. The SMA group showed excessive vertical development, particularly of the lower face. They demonstrated relatively larger anterior than posterior facial heights, due in part to a smaller cranial base angulation and a more anteriorly positioned mandibular ramus. Anteroposterior skeletal discrepancies of SMA patients, due to the combined effects of a protrusive maxilla and a retrusive mandible, were moderate. The intcrincisal angle of the SMA group was smaller than normal, due primarily to proclined maxillary incisors. Relative to palatal length, the SMA group had smaller anterior cranial base and mandibular corpus lengths. These results suggest abnormal craniofacial growth patterns of SMA patients. The etiology of the observed abnormalities seems to be complex and multifaceted, but attention to the treatment of malocclusion may be important for optimal nutrition and respiratory function.

ISSN:0031-3998    

出版商:OVID    

年代:1994

数据来源: OVID