摘要:

Human milk contains sphingomyelin (SM) as a major component of the phospholipid fraction. Galactosylceramide (cerebroside), a metabolite of sphingolipids, increases along with CNS myelination, and is generally considered a universal marker of myelination in all vertebrates. l-Cycloserine (LCS) is an inhibitor of serine palmitoyltransferase (SPT), a rate-limiting enzyme for sphingolipid biosynthesis that is reported to show increased activity with development of the rat CNS. The present study examined the effects of dietary SM on CNS myelination during development in LCS-treated rats. From 8 d after birth, Wistar rat pups received a daily s.c. injection (100 mg/kg) of LCS. From 17 d after birth, the animals were fed an 810 mg/100g of bovine SM-supplemented diet (SM-LCS group) or a nonsupplemented diet (LCS group). At 28 d after birth, the animals were killed and subjected to biochemical and morphometric analyses. The myelin dry weight, myelin total lipid content, and cerebroside content were significantly lower in the SM-LCS and LCS groups than in a group not treated with LCS (the non-LCS group). However, these levels were significantly higher in the SM-LCS group than in the LCS group. Morphometric analysis of the optic nerve revealed that the axon diameter, nerve fiber diameter, myelin thickness, and g value (used to compare the relative thickness of myelin sheaths around fibers of different diameter) were significantly lower in the LCS group than in the other groups, but were similar in the SM-LCS and non-LCS groups. These findings suggest that dietary SM contributes to CNS myelination in developing rats with experimental inhibition of activity.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Among various hypothetical mechanisms for thein vivoproduction of reactive oxygen species, transition metal-catalyzed reactions in cooperation with a biologic reducing agent like ascorbic acid or superoxide may be some of the most important. In the present study, we retrospectively examined the existence of non-protein-bound metal ions, an essentially hazardous pro-oxidant form of various transition metals, and the occurrence of metal-catalyzed reactive oxygen species production in cerebrospinal fluid (CSF) of 10 infants with hypoxic ischemic encephalopathy (HIE) subsequent to perinatal asphyxia and 12 control infants within 72 h of birth. Non-protein-bound iron was detected in eight out of 10 CSF samples from the HIE infants and its level was significantly correlated with Sarnat’s clinical stage, whereas none of the control infants had detectable non-protein-bound iron levels. Non-protein-bound copper was below the detection limit in all CSF samples from both groups. Ascorbic acid was significantly increased in the CSF of HIE infants when compared with that of controls (means, 664.9versus449.4 &mgr;M,p= 0.008).ortho-Tyrosine andmeta-tyrosine, which are highly specific and sensitive markers of protein oxidation induced by hydroxyl radicals, were significantly higher in HIE infants than in controls when evaluated by the ratio relative to their source amino acid, phenylalanine [means, 110.5versus75.4,p= 0.018 forortho-tyrosine/phenylalanine; 104.6versus67.7 (nM/&mgr;M × 102),p= 0.048 formeta-tyrosine/phenylalanine]. Both ratios were significantly correlated with non-protein-bound iron, but not with ascorbic acid. Our preliminary observations provide direct evidence that hydroxyl radicals are generated in the CNS during asphyxiation. Iron chelation therapy could be worth developing as a neuroprotective strategy for perinatal asphyxia.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

To examine the relationship of cytokines in blood of very preterm neonates with later diagnosis of spastic cerebral palsy (CP) compared with infants of similar gestational age without CP, we measured concentrations of inflammatory cytokines and other substances in archived neonatal blood by recycling immunoaffinity chromatography. Subjects were surviving children born before 32 wk gestational age (GA) to women without preeclampsia, 64 with later diagnoses of CP and 107 control children. The initial analyses were augmented by measurement of 11 cytokines by a bead-based flow analytic system (Luminex) in an additional 37 children with CP and 34 control children from the same cohort. Concentrations of examined substances did not differ by presence of indicators of infection in mother, infant, or placenta. On ANOVA, concentrations of a number of cytokines were significantly related to neonatal ultrasound abnormalities (periventricular leukomalacia, ventricular enlargement, or moderate or severe germinal matrix hemorrhage). None of the substances measured either by immunoaffinity chromatography or flow analytic methods, including IL-1, -6, and -8 and tumor necrosis factor-&agr;, was related to later diagnosis of CP or its subtypes. Inflammatory cytokines in neonatal blood of very premature infants did not distinguish those with later diagnoses of CP from control children.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Human airway epithelia express Ca2+-activated Cl−channels (CaCC) that are activated by extracellular nucleotides (ATP and UTP). CaCC is preserved and seems to be up-regulated in the airways of cystic fibrosis (CF) patients. In the present study, we examined the role of basolateral K+channels in CaCC-mediated Cl−secretion in native nasal tissues from normal individuals and CF patients by measuring ion transport in perfused micro Ussing chambers. In the presence of amiloride, UTP-mediated peak secretory responses were increased in CF compared with normal nasal tissues. Activation of the cAMP pathway further increased CaCC-mediated secretion in CF but not in normal nasal mucosa. CaCC-dependent ion transport was inhibited by the chromanol 293B, an inhibitor of cAMP-activated hKvLQT1 K+channels, and by clotrimazole, an inhibitor of Ca2+-activated hSK4 K+channels. The K+channel opener 1-ethyl-2-benzimidazolinone further increased CaCC-mediated Cl−secretion in normal and CF tissues. Expression of hSK4 as well as hCACC-2 and hCACC-3 but not hCACC-1 was demonstrated by reverse transcriptase PCR on native nasal tissues. We conclude that Ca2+-activated Cl−secretion in native human airway epithelia requires activation of Ca2+-dependent basolateral K+channels (hSK4). Co-activation of hKvLQT1 improves CaCC-mediated Cl−secretion in native CF airway epithelia, and may have a therapeutic effect in the treatment of CF lung disease.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Cystic fibrosis (CF) patients develop chronic lung infections associated with airway obstruction by viscous and insoluble mucus secretions. Although mucus glycoproteins (mucins) are thought to be responsible for mucus plugs, other glycoconjugate components of airway secretions have not been systematically evaluated. The aim of the present study was to determine whether chondroitin sulfate proteoglycans (CSPG) contribute to the insolubility of CF sputum. Sputa obtained from 18 CF patients were incubated with chondroitinase ABC (ChABC) or buffer (control) for 18 h at 37°C, and after centrifugation at 12,000g, the volume of the insoluble pellet and turbidity of the supernatant were determined as measures of solubility. ChABC caused a 70–90% reduction in supernatant turbidity and a 60–70% decrease in pellet volume of the 13 purulent CF sputa, but had much less effect on the five nonpurulent CF sputa tested. Similar results were obtained with two non-CF purulent and two non-CF, nonpurulent sputa. Gel electrophoresis, Western blot, and slot blot immunoassays with antichondroitin sulfate and antimucin antibodies revealed that purulent sputa (CF and non-CF) contained more CSPG and less mucin than nonpurulent sputa.In vitromixing experiments showed that mucin in nonpurulent sputa was reduced upon incubation with purulent sputa, presumably because of degradation or a loss of immunoreactive mucin epitopes from leukocyte and/or bacterial enzymes present in purulent sputa. Our results suggest that CSPG contribute more significantly than mucins to the insolubility of purulent tracheobronchial secretions from CF patients. Because purulent sputa from non-CF patients showed a similar pattern, our observations with CF sputa may have wider applicability.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

In preterm infants low plasma glucose concentrations are frequently observed. We hypothesized that the infants’ ability to adapt endogenous glucose production to diminishing exogenous supply is disturbed, but will improve with increasing gestational age. Glucose production rate and gluconeogenesis were measured using stable isotope techniques with [6,6-2H2]glucose and [2-13C]glycerol in 19 preterm infants (10 ≤ 30 wk and nine >30 wk gestational age) on d 5.0 ± 1.4 of life. Exogenous glucose was administered at a rate of 33 &mgr;mol·kg−1·min−1followed by 22 &mgr;mol·kg−1·min−1. In the first 2 h after the decrease in exogenous supply, plasma glucose concentration declined comparably in both groups: ≤30 wk, from 4.3 ± 1.2 to 3.2 ± 0.9 mM; >30 wk, from 3.7 ± 0.7 to 3.0 ± 0.6 mM. Thereafter, only in infants >30 wk an increase was observed, to 3.4 ± 0.8 mM. Glucose production rate increased comparably in both groups: ≤30 wk, from 6.0 ± 4.1 to 8.8 ± 3.4 &mgr;mol·kg−1·min−1; >30 wk, from 7.8 ± 4.6 to 11.6 ± 5.2 &mgr;mol·kg−1·min−1. This increase was equivalent to approximately 30% of the decline in exogenous glucose. Gluconeogenesis increased comparably in both groups: <30 wk, from 3.2 ± 1.2 to 4.5 ± 1.3 &mgr;mol·kg−1·min−1; >30 wk, from 4.3 ± 1.9 to 6.8 ± 2.9 &mgr;mol·kg−1·min−1. We conclude that preterm infants can only partly compensate a decline in exogenous glucose supply by increasing endogenous glucose production rate, probably because of limitations in the final common pathway of intracellular glucose metabolism (i.e.glucose-6-phosphatase). The ability to maintain the plasma glucose concentration after a decrease in exogenous supply is better preserved in infants >30 wk owing to more efficient adaptation of peripheral glucose utilization.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

We have previously demonstrated that very premature infants receiving total parenteral nutrition maintain normoglycemia primarily by glucose producedviagluconeogenesis and that the lipid emulsion is most important in supporting gluconeogenesis. It is, however, not clear whether this is a result of the glycerol or the fatty acid constituent. The purpose of the present study was to determine the effect of intravenous supplemental glycerol alone on glucose production and gluconeogenesis. Twenty infants (birth weight, 1014 ± 32 g; gestational age, 27 ± 1 wk) were studied on d 4 ± 1 (mean ± SE). All infants received glucose at 17 &mgr;mol/kg·min for 9 h (after an initial study hour with 33 &mgr;mol/kg·min). Eight infants received no additional substrate during the study, and 12 infants received supplemental glycerol at 5 (n= 6) or 10 &mgr;mol/kg·min (n= 6) over the last 5 h of study. In infants receiving glucose alone, between period 1 (study hours 4–5) and period 2 (study hours 9–10), rates of glucose production ([U-13C]glucose) decreased from 12.9 ± 1.2 to 7.4 ± 0.9 &mgr;mol/kg·min (p< 0.01). This was the result of decreased glycogenolysis but no change in gluconeogenesis ([U-13C]glucose mass isotopomer distribution analysis) (5.1 ± 0.6versus5.7 ± 0.4 &mgr;mol/kg·min) (ns). Glycerol infusion at 5 and 10 &mgr;mol/kg·min, respectively, maintained glucose production (despite comparable decrease in glycogenolysis) by increasing gluconeogenesis from 4.3 ± 0.2 to 6.3 ± 0.5 (p< 0.03), and 6.0 ± 0.7 to 8.8 ± 0.8 &mgr;mol/kg/min (p< 0.01). In very premature infants, parenteral glycerol enhances gluconeogenesis and attenuates time dependent decrease in glucose production.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Allergic disease (AD), including atopic eczema, asthma, allergic rhinitis, and food allergy, is characterized by an imbalance between cytokines produced by distinct T-helper cell subtypes. Whether this imbalance can be transferred from mother to breast milk remains to be established. The objective was to investigate the concentrations and interactions of nutritional and inflammatory factors in breast milk. Breast milk samples were collected from mothers with AD (n= 43) and without AD (n= 51). The concentrations of transforming growth factor (TGF)-&bgr;2, tumor necrosis factor-&agr;, IL-4, IL-10, prostaglandin E2, and cysteinyl leukotrienes were measured by immunoassays and fatty acid composition by gas chromatography. Mothers with AD had a lower concentration of TGF-&bgr;2in breast milk [median (interquartile range), 420 (278–701) ng/L] compared with those without AD [539 (378–1108) ng/L;p= 0.003], whereas other cytokines, prostaglandin E2, and cysteinyl leukotriene concentrations or fatty acid composition were not significantly different between the groups. The breast milk inflammatory factors and fatty acid composition were shown to be related. A positive association was observed between TGF-&bgr;2and the proportion of polyunsaturated fatty acids (p= 0.038) and a negative association between TGF-&bgr;2and the proportion of saturated fatty acids (p= 0.029) in breast milk. The reduced TGF-&bgr;2concentration in the breast milk of mothers with AD may interfere with the development of the mucosal immune system of the breast-fed infant. The observed associations between nutritional and inflammatory factors in breast milk suggest that it may be possible to influence the immunologic properties of breast milk by dietary intervention of the mother.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Squalene and noncholesterol sterols,e.g.lathosterol and plant sterols, the respective markers of cholesterol synthesis and absorption, are transported with cholesterol in serum lipoproteins. Their concentrations and ratios to cholesterol in serum and lipoproteins have not been carefully compared, especially in children and in marked hypercholesterolemia. Thus, we measured these variables with gas-liquid chromatography in 18 children with and 29 without familial hypercholesterolemia, all aged 5–17 y. Concentrations of most noncholesterol sterols were higher in serum, LDL, and intermediate density lipoprotein in the children with than those without familial hypercholesterolemia. Despite accumulation of noncholesterol sterols mainly in LDL (75% in familial hypercholesterolemia and 55% in non-familial hypercholesterolemia,p< 0.001), their ratios were mostly similar in serum and lipoproteins of the two groups. The ratios of squalene and lathosterol were higher in VLDL and intermediate density lipoprotein, whereas in LDL that of lathosterol was lower than the respective serum values in both groups. Absorption marker sterol ratios were highest in HDL in both groups. Thus, even though the ratios of noncholesterol sterols to cholesterol in serum reflect, in general, synthesis and absorption of cholesterol, their ratios in different lipoproteins could give additional information of cholesterol metabolism.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID

摘要:

Both severe impairments of brain development in untreated infants and acute reversible neurotoxic effects on brain function are clinical features of phenylketonuria (PKU). For determining whether impairments of cerebral energy metabolism play a role in the pathophysiology of PKU, quantitativein vivo31P magnetic resonance spectroscopy (MRS) was performed in a supratentorial voxel of 11 adult PKU patients and controls. Peak areas of inorganic phosphate; phosphocreatine; &agr;-, &bgr;-, and &ggr;-ATP; NAD; phosphomonoesters; phosphodiesters; and a broad phospholipid signal were converted to millimolar concentrations. Mg2+, pH, ADP, the phosphorylation potential, and the relative velocity of oxidative metabolism V/Vmaxwere derived. Clinical evaluation included mutation analysis, neurologic investigation, intelligence testing, magnetic resonance imaging, and concurrent plasma and brain phenylalanine (Phe), the last by1H-MRS. Phe loading was performed in five patients with an oral dose of 100 mg/kg body wt L-Phe monitored by spectral EEG analysis. Under steady-state conditions,31P-MRS revealed normal values for ATP, phosphocreatine, NAD, phosphomonoesters, phosphodiesters, Mg2+, and pH in PKU. ADP (+11%) and the phosphorylation potential (+22%) were increased. Peak areas of inorganic phosphate (−22%) and phospholipid (−8%) were decreased. ADP correlated with concurrent plasma (r = 0.65) and brain (r = 0.55) Phe. During the Phe load, blood Phe levels increased steeply. EEG revealed slowing of background activity. The phosphorylation potential decreased, whereas ADP and V/Vmaxincreased.In vivo31P-MRS demonstrated subtle abnormalities of cerebral energy metabolism in PKU in steady-state conditions that were accentuated by a Phe load, indicating a link between Phe neurotoxicity and imbalances of cerebral energy metabolism.

ISSN:0031-3998    

出版商:OVID    

年代:2003

数据来源: OVID