Characterization of a 21 amino acid peptide sequence of the laminin G2 domain that is involved in HNK-1 carbohydrate binding and cell adhesion

The N-linked HNK-1 carbohydrate expressed by several recognition molecules mediates the adhesion of early postnatal cerebellar neurons to the G2 domain of the terminal globular domain of the laminin α1 chain (H.Hall et al., submitted). To define this binding site more precisely, G2-derived synthetic peptides were used for binding and competition studies. Peptide 5-G2, comprising the amino acid residues 3431-3451 of G2, inhibited the interaction between the HNK-1-carrying glycolipid and laminin in a concentrationdependent and saturable manner. Peptides which overlap only partially with this sequence interfered less. Peptides comprising other amino acid sequences from G2, and peptides derived from G1 and G3 or a scrambled version of peptide 5-G2, did not show significant effects. Direct binding of peptide 5-G2 to the HNK-1 glycolipid was also demonstrated. Furthermore, peptide 5-G2 interfered in a concentration-dependent and saturable manner with the adhesion of early postnatal cerebellar neurons to laminin. These observations indicate that amino acid residues 3431-3451 of the laimnin G2 domain are involved in HNK-1 carbohydratemediated cell adhesio

Influence of preoperative serum N-terminal pro-brain type natriuretic peptide on the postoperative outcome and survival rates of coronary artery bypass patients

BACKGROUND: The N-terminal fragment of pro-brain type natriuretic peptide (NT-proBNP) is an established biomarker for cardiac failure. OBJECTIVE: To determine the influence of preoperative serum NT-proBNP on postoperative outcome and mid-term survival in patients undergoing coronary artery bypass grafting (CABG). METHODS: In 819 patients undergoing isolated CABG surgery preoperative serum NT-proBNP levels were measured. NT-proBNP was correlated with various postoperative outcome parameters and survival rate after a median follow-up time of 18 (0.5-44) months. Risk factors of mortality were identified using &#967;2, Mann-Whitney test, and Cox regression. RESULTS: NT-proBNP levels >430 ng/ml and >502 ng/ml predicted hospital and overall mortality (p<0.05), with an incidence of 1.6% and 4%, respectively. Kaplan-Meier analysis revealed decreased survival rates in patients with NT-proBNP >502 ng/ml (p=0.001). Age, preoperative serum creatinine, diabetes, chronic obstructive pulmonary disease, low left ventricular ejection fraction and BNP levels >502 ng/ml were isolated as risk factors for overall mortality. Multivariate Cox regression analysis, including the known factors influencing NT-proBNP levels, identified NT-proBNP as an independent risk factor for mortality (OR = 3.079 (CI = 1.149-8.247), p = 0.025). Preoperative NT-proBNP levels >502 ng/ml were associated with increased ventilation time (p=0.005), longer intensive care unit stay (p=0.001), higher incidence of postoperative hemofiltration (p=0.001), use of intra-aortic balloon pump (p<0.001), and postoperative atrial fibrillation (p=0.031) CONCLUSION: Preoperative NT-proBNP levels >502 ng/ml predict mid-term mortality after isolated CABG and are associated with significantly higher hospital mortality and perioperative complications

Nuclear factor I-A represses expression of the cell adhesion molecule L1

<p>Abstract</p> <p>Background</p> <p>The neural cell adhesion molecule L1 plays a crucial role in development and plasticity of the nervous system. Neural cells thus require precise control of L1 expression.</p> <p>Results</p> <p>We identified a full binding site for nuclear factor I (NFI) transcription factors in the regulatory region of the mouse <it>L1 </it>gene. Electrophoretic mobility shift assay (EMSA) showed binding of nuclear factor I-A (NFI-A) to this site. Moreover, for a brain-specific isoform of NFI-A (NFI-A bs), we confirmed the interaction <it>in vivo </it>using chromatin immunoprecipitation (ChIP). Reporter gene assays showed that in neuroblastoma cells, overexpression of NFI-A bs repressed L1 expression threefold.</p> <p>Conclusion</p> <p>Our findings suggest that NFI-A, in particular its brain-specific isoform, represses <it>L1 </it>gene expression, and might act as a second silencer of L1 in addition to the neural restrictive silencer factor (NRSF).</p

Gene expression analysis of nuclear factor I-A deficient mice indicates delayed brain maturation

BACKGROUND: Nuclear factor I-A (NFI-A), a phylogenetically conserved transcription/replication protein, plays a crucial role in mouse brain development. Previous studies have shown that disruption of the Nfia gene in mice leads to perinatal lethality, corpus callosum agenesis, and hydrocephalus. RESULTS: To identify potential NFI-A target genes involved in the observed tissue malformations, we analyzed gene expression in brains from Nfia(-/- )and Nfia(+/+ )littermate mice at the mRNA level using oligonucleotide microarrays. In young postnatal animals (postnatal day 16), 356 genes were identified as being differentially regulated, whereas at the late embryonic stage (embryonic day 18) only five dysregulated genes were found. An in silico analysis identified phylogenetically conserved NFI binding sites in at least 70 of the differentially regulated genes. Moreover, assignment of gene function showed that marker genes for immature neural cells and neural precursors were expressed at elevated levels in young postnatal Nfia(-/- )mice. In contrast, marker genes for differentiated neural cells were downregulated at this stage. In particular, genes relevant for oligodendrocyte differentiation were affected. CONCLUSION: Our findings suggest that brain development, especially oligodendrocyte maturation, is delayed in Nfia(-/- )mice during the early postnatal period, which at least partly accounts for their phenotype. The identification of potential NFI-A target genes in our study should help to elucidate NFI-A dependent transcriptional pathways and contribute to enhanced understanding of this period of brain formation, especially with regard to the function of NFI-A

Pathology of a mouse mutation in peripheral myelin protein P0 is characteristic of a severe and early onset form of human Charcot-Marie-Tooth type 1B disorder

Mutations in the gene of the peripheral myelin protein zero (P0) give rise to the peripheral neuropathies Charcot-Marie-Tooth type 1B disease (CMT1B), Déjérine-Sottas syndrome, and congenital hypomyelinating neuropathy. To investigate the pathomechanisms of a specific point mutation in the P0 gene, we generated two independent transgenic mouse lines expressing the pathogenic CMT1B missense mutation Ile106Leu (P0sub) under the control of the P0 promoter on a wild-type background. Both P0sub-transgenic mouse lines showed shivering and ultrastructural abnormalities including retarded myelination, onion bulb formation, and dysmyelination seen as aberrantly folded myelin sheaths and tomacula in all nerve fibers. Functionally, the mutation leads to dispersed compound muscle action potentials and severely reduced conduction velocities. Our observations support the view that the Ile106Leu mutation acts by a dominant-negative gain of function and that the P0sub-transgenic mouse represents an animal model for a severe, tomaculous form of CMT1B

Symmetry Breaking and Bifurcations in the Periodic Orbit Theory; 1, Elliptic Billiard

We derive an analytical trace formula for the level density of the two-dimensional elliptic billiard using an improved stationary phase method. The result is a continuous function of the deformation parameter (eccentricity) through all bifurcation points of the short diameter orbit and its repetitions, and possesses the correct limit of the circular billiard at zero eccentricity. Away from the circular limit and the bifurcations, it reduces to the usual (extended) Gutzwiller trace formula which for the leading-order families of periodic orbits is identical to the result of Berry and Tabor. We show that the circular disk limit of the diameter-orbit contribution is also reached through contributions from closed (periodic and non-periodic) orbits of hyperbolic type with an even number of reflections from the boundary. We obtain the Maslov indices depending on deformation and energy in terms of the phases of the complex error and Airy functions. We find enhancement of the amplitudes near the common bifurcation points of both short-diameter and hyperbolic orbits. The calculated semiclassical level densities and shell energies are in good agreement with the quantum mechanical ones

Cell surface sialylation and fucosylation are regulated by the cell recognition molecule L1 via PLCγ and cooperate to modulate embryonic stem cell survival and proliferation

AbstractCell surface glycosylation patterns are markers of cell type and status. However, the mechanisms regulating surface glycosylation patterns remain unknown. Using a panel of carbohydrate markers, we have shown that cell surface sialylation and fucosylation are upregulated in L1-transfected embryonic stem cells (L1-ESCs). Consistently, the mRNA levels of sialyltransferase ST6Gal1 and ST3Gal4, and fucosyltransferase FUT9 were significantly increased in L1-transfected ESCs. Activation of L1 signaling promoted cell survival and inhibited cell proliferation. ShRNAs knocking down FUT9, ST6Gal1 and ST3Gal4 blocked these effects. A phospholipase Cγ (PLCγ) inhibitor and shRNA reduced ST6Gal1, ST3Gal4 and FUT9 mRNA levels in the L1-ESCs. Thus, embryonic stem cell surface sialylation and fucosylation are regulated via PLCγ by L1, with which they cooperate to modulate cell survival and proliferation

Aortic Dissection Type A in Alpine Skiers

Patients and Methods. 140 patients with aortic dissection type A were admitted for cardiac surgery. Seventy-seven patients experienced their dissection in the winter season (from November to April). We analyzed cases of ascending aortic dissection associated with alpine skiing. Results. In 17 patients we found skiing-related aortic dissections. Skiers were taller (180 (172-200) cm versus 175 (157-191) cm, = 0.008) and heavier (90 (68-125) kg versus 80 (45-110) kg, = 0.002) than nonskiers. An extension of aortic dissection into the aortic arch, the descending thoracic aorta, and the abdominal aorta was found in 91%, 74%, and 69%, respectively, with no significant difference between skiers and nonskiers. Skiers experienced RCA ostium dissection requiring CABG in 17.6% while this was true for 5% of nonskiers ( = 0.086). Hospital mortality of skiers was 6% versus 13% in nonskiers ( = 0.399). The skiers live at an altitude of 170 (0-853) m.a.s.l. and experience their dissection at 1602 (1185-3105; &lt; 0.001) m.a.s.l. In 82% symptom start was during recreational skiing without any trauma. Conclusion. Skiing associated aortic dissection type A is usually nontraumatic. The persons affected live at low altitudes and practice an outdoor sport at unusual high altitude at cold temperatures. Postoperative outcome is good