ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Congenital disorders of glycosylation (CDGs) are a rapidly growing group of inherited disorders caused by defects in the synthesis and processing of the asparagine(ASN)-linked oligosaccharides of glycoproteins. The first CDG patients were described in 1980. Fifteen years later, a phosphomannomutase deficiency was found as the basis of the most frequent type, CDG-Ia. In recent years several novel types have been identified. TheN-glycosylation pathway is highly conserved from yeast to human, and the rapid progress in this field can largely be attributed to the systematic application of the knowledge of yeast mutants. Up to now, eight diseases have been characterized, resulting from enzyme or transport defects in the cytosol, endoplasmic reticulum, or Golgi compartment. CDGs affect all organs and particularly the CNS, except for CDG-Ib, which is mainly a hepatic-intestinal disease.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Cystic fibrosis (CF) is caused by mutations of the gene encoding for the CFTR (CF transmembrane conductance regulator) protein. The most frequent mutation, the &Dgr;F508 mutation, results in a defective cAMP-regulated chloride transport in the epithelial cells. The spectrum of clinical manifestations in patients bearing homozygous &Dgr;F508 mutations can vary considerably, suggesting that, in the patients with a mild disease, CFTR could be partly functional. To test this hypothesis, we explored in nasal ciliated epithelial cells (NCC) of 9 control subjects and 23 &Dgr;F508 homozygous patients the anion conductive pathway by a halide sensitive fluorescent dye assay SPQ (6-methoxy-N-3′-sulfopropylquinolinium) and theCFTRtranscript levels by RT-PCR. As 50% represented the lowest fraction of the control subjects NCC demonstrating a cAMP-dependent conductance, a CF patient was considered as “cAMP responder” if at least 50% of the NCC tested displayed a cAMP-dependent conductive pathway. According to these criteria, 8 of the 23 patients were considered as cAMP responders. They had a significantly less severe disease considering the respiratory function and infectious status. The amount of CFTR mRNA did not differ between the control subjects and the patients. No statistical correlation could be found between the transcript level and the expression of a cAMP conductive pathway. This cAMP-dependent Cl−conductance detected in homozygous NCC could be due to a residual CFTR activity and may explain the mild phenotypes observed in some &Dgr;F508 homozygous patients.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Persistent colonization withPseudomonas aeruginosa(PA) is a hallmark of the lung disease associated with cystic fibrosis (CF). Based on the concept that PA is not cleared from the lung by the host response in individuals with CF, we analyzed the capacity of PA to induce cell death in human alveolar macrophages (AM) and murine dendritic cells (DC), antigen presenting cells that play a central role in the initiation of pulmonary host defenses against pathogens, and evaluated if genetic modification can lead to protection against PA induced cell death. AM and DC were susceptible to cell death induced by the laboratory PA isolates PAO1, PAK and PA103, as well as a mucoid derivative of PAO1 and PA isolates derived from sputum of individuals with CF. Apoptosis, analyzed by TUNEL assay, was detectable in AM and DC as early as 3 h after infection with PA. In contrast, the same strains and doses of PA had little effect on the lung epithelial cell line A549 and primary cultures of human bronchial epithelial cellsin vitro. Pretreatment of DC with the caspase inhibitors VAD-fmk and YVAD-cmk reduced PA induced cell death (p< 0.05). Finally, genetic modification of DC to express CD40L using an adenovirus vector decreased the susceptibility of DC to cell death induced by PAO1 compared with DC infected with a control Ad vector (p< 0.01). The data demonstrate that DC and AM are susceptible to apoptosis induced by PA and that this response can be partially reversed by genetic modification with CD40L, a CD4+ T cell molecule that plays a central role in activating antigen presenting cells. These observations suggest a potential mechanism contributing to the persistence of PA in CF and suggest that genetic manipulation of antigen presenting cells with anti-apoptotic genes may be able to strengthen host defenses in CF.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Congenital disorder of glycosylation Ia (CDG-Ia) is an autosomal recessive disease, characterized by the impaired biosynthesis of the N-linked oligosaccharide chains of proteins due to a deficiency of phosphomannomutase (PMM), the enzyme converting mannose-6-phosphate into mannose-1-phosphate. We investigated the consequences of the altered N-linked glycoprotein (GP) biosynthesis on the quantity and quality of glycosphingolipids (GSLs) in fibroblasts of CDG-Ia patients. First, we found that CDG-Ia fibroblasts contain an increased amount of total GSLs when compared with normal fibroblasts. Further, we assessed by metabolic labeling of CDG-Ia fibroblasts with radioactive sugar precursors, including galactose and N-acetylmannosamine, that a diminished biosynthesis of cellular GPs is antagonized by an increased biosynthesis of GSLs. An increased GSL biosynthesis was also observed by means of radiolabeled lipid precursors including sphingosine and lactosylceramide. Notably, also the degradation of GLSs is slowed down in CDG-Ia fibroblasts. Finally, when we labeled normal human fibroblasts and CHO cells with radioactive galactose in the presence and absence of deoxymannojirimycin (dMM), an inhibitor of N-glycan processing, we found that this cellular model mimics what occurs in CDG-Ia fibroblasts. Since an inverse relationship between GP expression and GSL content does exist, we assume that increased glycosphingolipid biosynthesis is secondary to protein hypoglycosylation. Altogether, our data suggest that the cell metabolic machinery may be able to partially re-equilibrate protein hypoglycosylation with increased biosynthesis of glycosphingolipids, possibly to preserve the overall physico-chemical equilibrium of the outer layer of the plasma membrane.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Infants born to mothers heavily exposed to polychlorinated biphenyls (PCBs) and dibenzofurans (PCDFs) have earlier been reported to have increased prevalences of natal and neonatal teeth. Some tendency toward higher prevalence figures of natal and neonatal teeth can be seen in the literature in normal child populations during the last 40 y. We therefore decided to determine the present prevalence of these teeth in a Finnish population and to evaluate whether infants with natal and neonatal teeth are more exposed to PCBs, PCDFs, and polychlorinated dibenzo-p-dioxins (PCDDs) than infants on average. A total of 34,457 infants born in 1997–2000 in four hospitals in southern Finland were examined for natal and neonatal teeth. The exposure of the infant to PCBs and PCDD/Fs was evaluated by measuring the levels of 17 most toxic PCDD/F and 36 PCB congeners in his or her mother’s milk sample when the child was 4–8 wk old. A total of 34 infants had one or two natal (29 infants) or neonatal teeth (five infants). The milk analyses showed that the median level of PCDD/Fs as toxic equivalent (World Health Organization–recommended 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent quantity for PCDD/Fs in fat) was 11.9 pg/g in fat, and that of PCBs (World Health Organization–recommended 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalent quantity for PCBs) was 7.24 pg/g in fat. These levels corresponded to the prevailing levels. The results showed that the prevalence of natal and neonatal teeth was 1:1000. No association was found between pollutant levels and occurrence of natal and neonatal teeth, indicating that the prevailing levels of PCDD/Fs and PCBs are likely to be below the threshold to cause perinatal eruption of teeth.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Vitamin K deficiency is a relatively common condition in neonates. However, the role of vitamin K in neonatal bone metabolism remains to be determined. Osteocalcin (OC) is the most abundant noncollagenous protein in bone, and is regulated to be &ggr;-carboxylated by vitamin K. In this study, we measured &ggr;-carboxylated osteocalcin (Gla-OC) and non- or undercarboxylated osteocalcin (Glu-OC) separately, and examined the effects of vitamin K on osteocalcin metabolism. Eighteen full-term healthy neonates were enrolled in this study. In the cord and d-5 blood samples, the OC levels were determined by three different methods to examine the intact OC by immunoradiometric assay (IRMA), Gla-OC, and Glu-OC. Serum vitamin K fractions, hepaplastin test, and type 1 procollagen carboxyl extension peptide were also determined. Urine samples were also collected from the first voiding and on d 5 to determine urinary pyridinoline, deoxypyridinoline, and &ggr;-carboxylated glutamic acid. Serum levels of phylloquinone (PK) and menaquinone (MK)-4 increased on d 5 following vitamin K administration and increased intake in breast milk and/or formula. The OC levels determined by IRMA did not change between cord and d-5 blood samples, but the Gla-OC level increased remarkably and Glu-OC reduced to a negligible level. OC in cord blood is mainly Glu-OC, and Glu-OC is replaced with Gla-OC within 5 d of life after vitamin K supplement. The IRMA assay fails to distinguish Gla-OC from Glu-OC and caution is needed to estimate bone turnover with this method in the perinatal period.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID

摘要:

Recent non-placebo-controlled studies of the bisphosphonate pamidronate have shown it to be effective in reducing fractures and improving bone density in infants and children with osteogenesis imperfecta (OI). To evaluate the effects of bisphosphonate treatment in a controlled study, theoim/oimmouse model of OI was studied. Nursing infant mouse pups (∼ 2 wk old) with moderate to severe OI (oim/oimmouse) and age- and background-matched control mice (+/+) were treated either with the third-generation bisphosphonate alendronate (ALN), or with saline. Fracture risk, bone quality, and growth were evaluated over a 12-wk treatment period. ALN at a dose of 0.03 mg/kg/d or saline was administeredvias.c. injection to infantoim/oimand wild-type (+/+) mice from 2 to 14 wk of age (n= 20 per subgroup). The average number of fractures sustained by the ALN-treatedoim/oimmice was reduced significantly compared with the untreatedoim/oimmice (0.7 ± 0.7 fractures/mouseversus2.0 ± 0.2 fractures/mouse). Bone density increased significantly in the femur and the spine with treatment (2.0 ± 0.5versus1.2 ± 0.5 in femur and 2.1 ± 0.5versus1.6 ± 0.5 in spine). Histologic evaluation revealed the percentage of metaphyseal tibial bone increased significantly with treatment in both +/+ andoim/oimmice. Mechanical testing revealed an increase in structural stiffness for both treated +/+ andoim/oimmice compared with untreated animals. None of the material properties examined were significantly altered with treatment, nor was spinal curvature affected. Weight gain and long bone growth were comparable in the treated and untreatedoim/oimmice. In wild-type mice, femur lengths were significantly shorter in the treated mice compared with untreated counterparts. This animal study demonstrates that treatment of OI in mice as early as 2 wk of age with ALN appears to be effective in reducing fractures and increasing bone properties. Based on the data from this study, ALN therapy in infants with OI should prove to be effective.

ISSN:0031-3998    

出版商:OVID    

年代:2002

数据来源: OVID