摘要:

&NA;The genome sequencing approach has proved to be highly effective and invaluable for gaining an insight on structure of bacteria genomes and the biology and evolution of bacteria. The diversity of bacteria genomes is beyond expectation. Gaining a full understanding of the biology and pathogenic mechanisms of these pathogens will be a major task because on an average only approximately 69% of the encoded proteins in each genome have known functions. Genome sequence analyses have identified novel putative virulence genes, vaccine candidates, targets for antibacterial drugs, and specific diagnostic probes. Microarray technology that makes use of the genomic sequences of human and bacterial pathogens will be a major tool for gaining full understanding of the complexity of host‐pathogen interactions and mechanisms of pathogenesis.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;Colonization byEscherichia. coliin infants might have decreased in the last decades, owing to changes in hospital routines and family lifestyle. In this study, theE. coliflora was characterized in 70 healthy Swedish infants followed for the first year of life.E. coliwas isolated from rectal swabs obtained at 3 d of age and quantified in fecal samples collected at 1, 2, 4, and 8 wk of age and at 6 and 12 mo of age. Strains were typed using random amplified polymorphic DNA, and their virulence factor genes were identified by multiplex PCR. Colonization byE. colioccurred late; only 61% of the infants were positive by 2 mo of age. The turnover of individual strains in the microflora was slow (1.5 strains per infant during 6 mo, 2.1 during 1 y). Environmental factors, such as siblings, pets, or feeding mode, did not influence colonization kinetics or strain turnover rate. Genes encoding type 1 fimbriae, P fimbriae, and hemolysin were significantly more common inE. colistrains persisting for at least 3 wk in the microflora than in transient strains. The P‐fimbrial class III adhesin gene was more common inE. colifrom children who had a cat in their homes than inE. colifrom children without pets (p= 0.01); this adhesin type is common inE. colifrom cats. The late colonization and lowE. colistrain turnover rate suggest limited exposure of Swedish infants toE. coli.Our results confirm that P fimbriae and other virulence factors facilitate persistence ofE. coliin the human colonic microflora.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;Maternal milk is the major source of nutrients and growthpromoting substances in the first weeks of life for the majority of neonates. Epidermal growth factor (EGF) and transforming growth factor‐&agr; (TGF‐&agr;) are trophic peptides present in human milk with significant healing effects on injured gastrointestinal mucosa. Decreasing gestational age of neonates is associated with higher risk of developing gastrointestinal disorders, and human milk provides better protection against these diseases compared with formula. The aim of this study was to evaluate the concentrations of EGF and TGF‐&agr; in human milk collected from mothers with infants born: extremely preterm, preterm, and full term. Milk samples were collected at the end of first, second, and fourth week postpartum from each mother of infants born in one of the three gestational age groups: extremely preterm (23‐27 wk,n= 16), preterm (32‐36 wk,n= 16), and full term (38‐42 wk,n= 15). Milk concentrations of EGF and TGF‐&agr; were quantified with a homologous RIA in the milk aqueous fraction. Concentrations of EGF in human milk from the extremely preterm group (23‐27 wk) were significantly higher compared with values from the preterm and full‐term groups throughout the first month of lactation. A similar pattern was observed with human milk TGF‐&agr;; however, milk TGF‐&agr; levels were lower than EGF. In conclusion, we have found higher concentrations of EGF and TGF‐&agr; in human milk of mothers with extremely preterm babies. These data may indicate the potential importance of milk‐borne EGF and TGF‐&agr; for the development of extremely premature infants.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;Infant mortality and stillbirth rates in Bolivia are high and birth weights are low compared with other South American countries. Most Bolivians live at altitudes of 2500 m or higher. We sought to determine the impact of high altitude on the frequency of preeclampsia, gestational hypertension, and other pregnancy‐related complications in Bolivia. We then asked whether increased preeclampsia and gestational hypertension at high altitude contributed to low birth weight and increased stillbirths. We performed a retrospective cohort study of women receiving prenatal care at low (300 m, Santa Cruz,n= 813) and high altitude (3600 m, La Paz,n= 1607) in Bolivia from 1996 to 1999. Compared with babies born at low altitude, high‐altitude babies weighed less (3084 ± 12 gversus3366 ± 18 g,p< 0.01) and had a greater occurrence of intrauterine growth restriction [16.8%; 95% confidence interval (CI): 14.9‐18.6versus5.9%; 95% CI: 4.2‐7.5;p< 0.01]. Preeclampsia and gestational hypertension were 1.7 times (95% CI: 1.3‐2.3) more frequent at high altitude and 2.2 times (95% CI: 1.4‐3.5) more frequent among primiparous women. Both high altitude and hypertensive complications independently reduced birth weight. All maternal, fetal, and neonatal complications surveyed were more frequent at high than low altitude, including fetal distress (odds ratio, 7.3; 95% CI: 3.9‐13.6) and newborn respiratory distress (odds ratio, 7.3; 95% CI: 3.9‐13.6;p< 0.01). Hypertensive complications of pregnancy raised the risk of stillbirth at high (odds ratio, 6.0; 95% CI: 2.2‐16.2) but not at low altitude (odds ratio, 1.9; 95% CI: 0.2‐17.5). These findings suggest that high altitude is an important factor worsening intrauterine mortality and maternal and infant health in Bolivia.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;An alternation of &ggr;‐aminobutyric acid (GABA)‐ergic neurotransmission has been implicated as an etiologic factor in epileptogenesis. Missense mutations in theGABRG2gene, which encodes the &ggr;2 subunit of central nervous GABAAreceptors, have recently been described in one family with childhood absence epilepsy and febrile seizures (FSs). FSs represent the majority of childhood seizures and have a genetic predisposition. It is not known, however, whether polymorphisms in those genes involved in familial epilepsies also contribute to the pathogenesis of FSs. By performing an association study, we used singlenucleotide polymorphisms to investigate the distribution of genotypes ofGABRG2in patients with FSs. A total of 104 children with FSs and 83 normal control subjects were included in the study. PCR was used to identify the C/T and A/G polymorphisms of theGABRG2gene on chromosome 5q33. Genotypes and allelic frequencies for theGABRG2gene polymorphisms in both groups were compared. TheGABRG2(nucleotide position 3145 in intron G→A) gene in both groups was not significantly different. In contrast, the number of individuals with theGABRG2(SNP211037)‐C/C genotype in patients with FSs was significantly greater compared with that in healthy control subjects (p= 0.017), and theGABRG2(SNP211037)‐C allele frequency in patients with FSs was significantly higher than that in healthy control subjects (p= 0.009). The odds ratio for developing FSs in individuals with theGABRG2(SNP211037)‐C/C genotype was 2.56 compared with individuals with theGABRG2(SNP211037)‐T/T genotype. These data suggest that theGABRG2gene might be one of the susceptibility factors for FSs.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;Langerhans cell histiocytosis is a rare disease with an unknown etiology and poorly understood pathogenesis. Immunologic, viral, and proliferative clonality causes have all been considered. To determine whether Langerhans cell histiocytosis and its two main subgroups, single‐system and multisystem disease, are associated with HLA‐A, ‐B, ‐Cw, or ‐DR alleles, a total of 84 patients <15 y of age at the time of diagnosis and of Nordic origin were analyzed, 82 for HLA class I and 76 for HLA class II. Stratification of the patients into two subgroups, singlesystem disease (skin only, and monostotic and polyostotic disease) and multisystem disease with or without organ dysfunction, showed that patients with single‐system disease (17 of 45, 38%) more often (p= 0.00018 and, after correction,p= 0.029) had the phenotypeHLA‐DRB1*03compared with patients with multisystem disease (1 of 31, 3%). In the patients with multisystem disease a nonsignificant reduction of the frequency of this phenotype was seen compared with controls (p= 0.02, uncorrected). In 14 of the patients with single‐system disease, but none with multisystem disease, the deduced haplotypeHLA‐A*01, B*08, DRB1*03was found. High‐resolution typing, performed in nine patients, revealed that all had theHLA‐A*0101, B*0801, DRB1*0301, DQB1*0201alleles. Our findings suggest an immunogenetic heterogeneity in the two clinical entities of Langerhans cell histiocytosis and indicate thatHLA‐DRB1*03may play a protective role against developing multisystem disease. Further studies to confirm these findings are desired.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

ABSTRACTVery preterm infants developing bronchopulmonary dysplasia frequently show a compromised growth in the neonatal period especially when steroids are given to facilitate weaning from the ventilator. The aim of this study was to evaluate the short‐term effect of dexamethasone (DEXA) on the GH‐IGF axis in ventilated very preterm infants developing bronchopulmonary dysplasia. We studied 10 very preterm artificially ventilated infants with bronchopulmonary dysplasia [median (range) gestational age 27.5 wk (25.9‐32.0 wk), median (range) birth weight 970 g (610‐2150 g)] immediately before and 2 d after the start of DEXA treatment. On both days of study, serum GH profiles were obtained, and serum IGF‐I and IGF binding protein (IGFBP) −1 and −3 levels were measured. The ventilation score and the nutritional intake were calculated. Before the start of DEXA treatment, the median serum mean GH level was 12.0 μg/L (6‐28.4 μg/L), whereas 2 d after the start of DEXA treatment the median serum mean GH level declined significantly to a value of 4.4 μg/L (1.7‐11.9 μg/L). During DEXA treatment, mean, baseline, and maximal GH levels (Pulsar analysis) were significantly lower compared with pretreatment levels (p< 0.01,p< 0.01, andp< 0.05, respectively). Serum IGF‐I and IGFBP‐3 levels did not decline during DEXA. Serum IGFBP‐1 levels were significantly lower compared with pretreatment levels (p< 0.01). Serum GH levels during DEXA treatment were correlated with neither the time interval between the administration of DEXA and the second GH profile nor the cumulative DEXA dose administered. Ventilation score and nutritional intake did not significantly correlate with serum GH, IGF‐I, or IGFBP‐1 or ‐3 levels, either before or after the start of DEXA. Two days of DEXA treatment in very preterm ventilated infants has a suppressive effect on serum GH levels, without an acute decline in serum IGF‐I levels. A concomitant decrease in serum IGFBP‐1 levels was found.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;Recentin vitrostudies reported that nitric oxide release and pulmonary vasorelaxation can be mediated by endothelial &agr;2‐adrenoceptor activation. As norepinephrine (&agr;1‐,&agr;2‐, and &bgr;1‐adrenoceptor agonist) was found to induce pulmonary vasodilation in the ovine fetus, we hypothesized that &agr;2‐adrenoceptors may modulate basal pulmonary vascular tone and mediate the vascular effect of norepinephrine during fetal life. To determine the role of &agr;2‐adrenoceptors and the mechanisms of norepinephrine‐mediated vasodilation in the fetal pulmonary circulation, we tested, in chronically prepared late‐gestation fetal lambs, the hemodynamic response to1) yohimbine (&agr;2antagonist);2) UK 14,304 (&agr;2agonist) with and without L‐nitro‐arginine (nitric oxide synthase inhibitor); and3) norepinephrine infusion with and without yohimbine. We found that yohimbine increased mean pulmonary artery pressure by 15% (p< 0.05), decreased pulmonary flow by 22% (p< 0.01), and increased pulmonary vascular resistance by 51% (p< 0.01). UK 14,304 increased pulmonary flow by 145% (p< 0.01) and decreased pulmonary vascular resistance by 58% (p< 0.01). L‐Nitro‐arginine abolished the UK 14,304‐mediated pulmonary vasodilation. Norepinephrine (0.5 μg·kg−1·min−1) increased both pulmonary flow by 61% (p< 0.01) and pulmonary arterial pressure by 13% (p< 0.01) and decreased pulmonary vascular resistance by 33% (p< 0.01). Yohimbine abolished the norepinephrine‐induced pulmonary vasodilation. This study suggests that1) a basal &agr;2‐adrenoceptor activation‐induced pulmonary vasodilation exists during fetal life;2) the pulmonary vascular effects of &agr;2‐adrenoceptor activation are related at least in part to nitric oxide production; and3) the norepinephrine‐mediated pulmonary vasodilation involves &agr;2‐adrenoceptor activation. As a surge of norepinephrine exists at birth, we speculate that norepinephrine and endothelial &agr;2‐adrenoceptor activation may play a significant role in pulmonary vasodilation at birth.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;The preterm infant has functionally immature monocytes. The effects of common clinical interventions and exposures that might modulate inflammation were evaluated using monocytes isolated from blood of preterm lambs [130 d gestational age (GA)], near‐term lambs (141 d GA), and adult sheep. Endotoxin stimulated hydrogen peroxide production by adult monocytes, but monocytes from 130‐d and 141‐d GA lambs had a reduced and delayed hydrogen peroxide production. Endotoxin did not decrease apoptosis of monocytes from 130‐d and 141‐d GA lambs but decreased apoptosis of adult monocytes. Dexamethasone increased the phagocytosis of bacteria and apoptotic cells by adult monocytes by 35% but not by monocytes from 130‐d and 141‐d GA lambs. Synthetic and natural surfactants and dipalmitoylphosphatidylcholine increased phagocytosis of apoptotic cells by monocytes from preterm, term, and adult sheep. Monocytes from preterm and term lambs differ from adult monocytes in tests of both the initiation and the resolution of inflammation. The reduced phagocytosis of apoptotic cells by monocytes from the preterm may contribute to prolonged inflammation in diseases such as bronchopulmonary dysplasia.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

&NA;To determine airway ion transport in term infants on the first day of postnatal life, and to test the hypothesis that infants born without labor have reduced sodium absorption, we measured nasal potential difference using a modified perfusion protocol suitable for newborn infants. We examined maximal stable baseline potential difference, the change after perfusion with 10−4M amiloride (&Dgr;amil), and the change after perfusion with a zerochloride solution (&Dgr;zero Cl−) in infants born after elective cesarean section (n= 21) or normal labor (n= 20). Maximal stable baseline potential difference was not different in the two cohorts (−24.0 mV, range −9 to −64 mVversus−25.5 mV, range −6 to −44 mV). The majority of infants in both cohorts showed a substantial fall in potential difference after amiloride perfusion, and there was little capacity for chloride secretion. These results demonstrate a fluid absorptive pattern in the airways on the first postnatal day. In these well infants, the ion transport phenotype was not dependent on the presence or absence of labor.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID