Mechanics of the maxillary central incisor. Influence of the periodontal ligament represented by beam elements

This study aimed to evaluate the influence of loading on a maxillary central incisor with the periodontal ligament (PDL) represented by 2D elastic beam elements using a 2D finite element analysis. Two models (M) were built varying the PDL representation: Mh (homogeneous PDL) and Mht (heterogeneous PDL with beam3 elements). Stress and displacements were determined for three loading conditions (L): Ll, lingual face loading at 45° with the tooth long axis; Li, perpendicular to the incisal edge; and Lip, on the incisal edge, parallel to the tooth long axis. Evaluation was performed on ANSYS software. Lip provided lower stress variation on the tooth and support structures when compared to Ll and Li. PDL's influence on stress values was lower for Lip. Oblique loading showed stress and displacement not observed in parallel loading condition through PDL's heterogeneous representation and it is probably incompatible with the in vivo condition.     

Polygonum nepalense Meisn. avventizia nel Bellunese

Abstract

Polygonum nepalense Meisn. has been found naturalteed together with Collomia linearis Nutt. near Belluno, Northern Italy. Polygonum nepalense belongs to the Cephalophilon-Section, an annual with creeping-ascending branched stems, winged petioles and 2 rounded, basal auricles, leaf-blade ovate-triangular, somehow fleshy, ochreas tubular with a tuft of hairs at the base, peduncles glandular-pubescent; spikes globose, densely flowered, styles 2 (seldom 3), nutlets trigonous, dark-brown, about 1-1.5 mm long. This species has not been indicated yet in the Alps but is cited as a rather common one in humid localities, damp woods in mountains, tea- and chinchona-plantations in Asia and India. Abundant on the Himalaya up to 10,000 ft., known also in Bengal, Ceylon, Assam, Burma, China, Java, Formosa, Japan and Abyssinia.     

Photochemical transformations and bacterial utilization of high-molecular-weight dissolved organic carbon in a southern Louisiana tidal stream (Bayou Trepagnier)

UVirradiation of dissolved organic carbon (DOC) in the laboratory can producesmall, labile organic compounds utilizable by microbes, but few studies haveattempted to document this process in situ. ¹³Cnuclear magnetic resonance (NMR) was used to examine the bulk chemicalcomposition of natural and laboratory-irradiated high-molecular-weight DOC(HMW-DOC) from shaded (150 mol m^–2s^–1 average light in surface water) and open (1500mol m^–2 s^–1) field sitesoverone and a half years. ¹³C NMR revealed only small differences incarbon functional groups between laboratory irradiated and non-irradiatedHMW-DOC. However, bacterial protein productivity per cell (BPP) was enhanced innaturally irradiated samples of HMW-DOC in a field mesocosm experiment (p <0.05), suggesting that bacterial growth was enhanced by photochemicalproductionof labile DOC substrates. Absorbance characteristics such as spectral slope,absorbance at 350 nm, and the absorbance ratio 250nm/365 nm revealed that HMW-DOC was photoreactive,yetno differences in these values were found between samples irradiated with andwithout UV-B. In experiments conducted with simulated solar radiation in thelaboratory and with natural light in the field mesocosm experiment, UV-A(320–400 nm) and photosynthetically active radiation (PAR;400–700 nm) were more effective than UV-B (280–320nm) in HMW-DOC photolysis.     

Hantavirus pulmonary syndrome-associated hantaviruses contain conserved and functional ITAM signaling elements

Hantaviruses infect human endothelial and immune cells, causing two human diseases, hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). We have identified key signaling elements termed immunoreceptor tyrosine-based activation motifs (ITAMs) within the G1 cytoplasmic tail of all HPS-causing hantaviruses. ITAMs direct receptor signaling within immune and endothelial cells and the presence of ITAMs in all HPS-causing hantaviruses provides a means for altering normal cellular responses which maintain vascular integrity. The NY-1 G1 ITAM was shown to coprecipitate a complex of phosphoproteins from cells, and the G1 ITAM is a substrate for the Src family kinase Fyn. The hantavirus ITAM coprecipitated Lyn, Syk, and ZAP-70 kinases from T or B cells, while mutagenesis of the ITAM abolished these interactions. In addition, G1 ITAM tyrosines directed intracellular interactions with Syk by mammalian two-hybrid analysis. These findings demonstrate that G1 ITAMs bind key cellular kinases that regulate immune and endothelial cell functions. There is currently no means for establishing the role of the G1 ITAM in hantavirus pathogenesis. However, the conservation of G1 ITAMs in all HPS-causing hantaviruses and the role of these signaling elements in immune and endothelial cells suggest that functional G1 ITAMs are likely to dysregulate normal immune and endothelial cell responses and contribute to hantavirus pathogenesis.     

Expression cloning of a cDNA encoding M1/69-J11d heat-stable antigens

The differentiation Ag identified by the mAb M1/69 and J11d (commonly referred to as heat-stable Ag) are found in structurally heterogeneous forms on the surfaces of many types of murine hemopoietic cells. The extinction of expression of these antigens is associated with thymocyte maturation and Ig class switching in B cells, as well as terminal differentiation of macrophages. A cDNA encoding the M1/69-J11d peptide was cloned from a hemopoietic progenitor cell line by immunoselection of COS cells transfected with expression libraries. The cloned cDNA is a copy of a gene that is transcribed in M1/69-J11d+ lymphoid, myeloid, and erythroid cells. This gene could be responsible for the expression of all forms of the M1/69-J11d Ag, although there are homologous genes that may encode some forms of the Ag that are specifically expressed in bone marrow. The cloned cDNA encodes a surprisingly small peptide, predicted to contain only 30 amino acids after removal of a signal sequence and displacement of the C-terminal region by the glycosyl-phosphatidylinositol group that anchors the peptide to the cell surface. Almost all of the mass of the M1/69-J11d Ag accumulates through extensive N- and O-linked glycosylation at multiple sites in the short peptide. These carbohydrates are likely to execute the functions of M1/69-J11d Ag, which could be specialized to each cell type as a consequence of differential glycosylation.     

Unexpected mode of action of sweet potato β-amylase on maltooligomer substrates

β-Amylase (EC 3.2.1.2), one of the main protein of the sweet potato, is an exo-working enzyme catalyzing the hydrolysis of α(1,4) glycosidic linkages in polysaccharides and removes successively maltose units from the non-reducing ends. The enzyme belongs to glycoside hydrolase GH14 family and inverts the anomeric configuration of the hydrolysis product. Multiple attack or processivity is an important property of polymer active enzymes and there is still limited information about the processivity of carbohydrate active enzymes. Action pattern and kinetic measurements of sweet potato β-amylase were made on a series of aromatic chromophor group-containing substrates (degree of polymerization DP 3-13) using HPLC method. Measured catalytic efficiencies increased with increasing DP of the substrates. Processive cleavage was observed on all substrates except the shortest pentamer. The mean number of steps without dissociation of enzyme–product complex increases with DP of substrate and reached 3.3 in case of CNPG11 indicating that processivity on longer substrates was more significant. A unique transglycosylation was observed on those substrates, which suffer processive cleavage and the substrates were re-built by the enzyme. Our results are the first presentation of a transglycosylation during an inverting glycosidase catalyzed hydrolysis. The yield of transglycosylation was remarkable high as shown in the change of the CNPG11 quantity. The CNPG11 concentration was doubled (from 0.24 to 0.54 mM) in the early phase of the reaction.     

Outcrossing potential between 11 important genetically modified crops and the Chilean vascular flora

The potential impact of genetically modified (GM) crops on biodiversity is one of the main concerns in an environmental risk assessment (ERA). The likelihood of outcrossing and pollen‐mediated gene flow from GM crops and non‐GM crops are explained by the same principles and depend primarily on the biology of the species. We conducted a national‐scale study of the likelihood of outcrossing between 11 GM crops and vascular plants in Chile by use of a systematized database that included cultivated, introduced and native plant species in Chile. The database included geographical distributions and key biological and agronomical characteristics for 3505 introduced, 4993 native and 257 cultivated (of which 11 were native and 246 were introduced) plant species. Out of the considered GM crops (cotton, soya bean, maize, grape, wheat, rice, sugar beet, alfalfa, canola, tomato and potato), only potato and tomato presented native relatives (66 species total). Introduced relative species showed that three GM groups were formed having: a) up to one introduced relative (cotton and soya bean), b) up to two (rice, grape, maize and wheat) and c) from two to seven (sugar beet, alfalfa, canola, tomato and potato). In particular, GM crops presenting introduced noncultivated relative species were canola (1 relative species), alfalfa (up to 4), rice (1), tomato (up to 2) and potato (up to 2). The outcrossing potential between species [OP; scaled from ‘very low’ (1) to ‘very high’ (5)] was developed, showing medium OPs (3) for GM–native relative interactions when they occurred, low (2) for GMs and introduced noncultivated and high (4) for the grape‐Vitis vinifera GM–introduced cultivated interaction. This analytical tool might be useful for future ERA for unconfined GM crop release in Chile.     

Characterization of a caveolin‐1 mutation associated with both pulmonary arterial hypertension and congenital generalized lipodystrophy

Congenital generalized lipodystrophy (CGL) and pulmonary arterial hypertension (PAH) have recently been associated with mutations in the caveolin‐1 ( CAV1 ) gene, which encodes the primary structural protein of caveolae. However, little is currently known about how these CAV1 mutations impact caveolae formation or contribute to the development of disease. Here, we identify a heterozygous F160X CAV1 mutation predicted to generate a C‐terminally truncated mutant protein in a patient with both PAH and CGL using whole exome sequencing, and characterize the properties of CAV1 , caveolae‐associated proteins and caveolae in skin fibroblasts isolated from the patient. We show that morphologically defined caveolae are present in patient fibroblasts and that they function in mechanoprotection. However, they exhibited several notable defects, including enhanced accessibility of the C‐terminus of wild‐type CAV1 in caveolae, reduced colocalization of cavin‐1 with CAV1 and decreased stability of both 8S and 70S oligomeric CAV1 complexes that are necessary for caveolae formation. These results were verified independently in reconstituted CAV1 ^?/? mouse embryonic fibroblasts. These findings identify defects in caveolae that may serve as contributing factors to the development of PAH and CGL and broaden our knowledge of CAV1 mutations associated with human disease.      

B Cell Deficient Mice Are Protected from Biliary Obstruction in the Rotavirus-Induced Mouse Model of Biliary Atresia

A leading theory regarding the pathogenesis of biliary atresia (BA) is that bile duct injury is initiated by a virus infection, followed by an autoimmune response targeting bile ducts. In experimental models of autoimmune diseases, B cells have been shown to play an important role. The aim of this study was to determine the role of B cells in the development of biliary obstruction in the Rhesus rotavirus (RRV)-induced mouse model of BA. Wild-type (WT) and B cell-deficient (Ig-α^-/-) mice received RRV shortly after birth. Ig-α^-/- RRV-infected mice had significantly increased disease-free survival rate compared to WT RRV-infected BA mice (76.8% vs. 17.5%). In stark contrast to the RRV-infected BA mice, the RRV-infected Ig-α^-/- mice did not have hyperbilirubinemia or bile duct obstruction. The RRV-infected Ig-α^-/- mice had significantly less liver inflammation and Th1 cytokine production compared to RRV-infected WT mice. In addition, Ig-α^-/- mice had significantly increased numbers of regulatory T cells (Tregs) at baseline and after RRV infection compared to WT mice. However, depletion of Tregs in Ig-α^-/- mice did not induce biliary obstruction, indicating that the expanded Tregs in the Ig-α^-/- mice were not the sole reason for protection from disease. Conclusion: B cell deficient Ig-α^-/- mice are protected from biliary obstruction in the RRV-induced mouse model of BA, indicating a primary role of B cells in mediating disease pathology. The mechanism of protection may involve lack of B cell antigen presentation, which impairs T-cell activation and Th1 inflammation. Immune modulators that inhibit B cell function may be a new strategy for treatment of BA.