Association of Altered Collagen Content and Lysyl Oxidase Expression in Degenerative Mitral Valve Disease

Background—Collagen cross-linking is mediated by lysyl oxidase (LOX) enzyme in the extracellular matrix (ECM) of mitral valve leaflets. Alterations in collagen content and LOX protein expression in the ECM of degenerative mitral valve may enhance leaflet expansion and disease severity. Methods—Twenty posterior degenerative mitral valve leaflets from patients with severe mitral regurgitation were obtained at surgery. Five normal posterior mitral valve leaflets procured during autopsy served as controls. Valvular interstitial cells (VICs) density was quantified by immunohistochemistry, collagen types I and III by picro-sirius red staining and immunohistochemistry, and proteoglycans by alcian blue staining. Protein expression of LOX and its mediator TGFβ1 were quantified by immunofluorescence and gene expression by PCR. Results—VICs density was increased, structural type I collagen density was reduced, while reparative type III collagen and proteoglycan densities were increased (p \u3c 0.0001) with an increase in spongiosa layer thickness in myxomatous valves. These changes were associated with a reduction in LOX (p \u3c 0.0001) and increase in TGFβ1 protein expression (p \u3c 0.0001). However, no significant change was seen in gene expression. Linear regression analysis identified a correlation between type I collagen density and LOX grade (R2 = 0.855; p \u3c 0.0001). Conclusions—Reduced type I collagen density with a simultaneous increase in type III collagen and proteoglycan densities possibly contributes to spongiosa layer expansion resulting in incompetent mitral valve leaflets. Observed changes in type I and III collagen densities in DMVD may be secondary to alterations in LOX protein expression, contributing to disorganization of ECM and disease severity

Isolation, Identification, and Pathogenicity of a Virulent Aeromonas jandaei Associated with Mortality of Farmed Pangasianodon hypophthalmus, in India

The present study was conducted to investigate the bacterial pathogens involved in the mortality of cultured Pangasianodon hypophthalmus. Diseased fish samples were collected from Maharashtra, India for the isolation of pathogenic bacteria. The pathogenic bacterial isolates were identified using 16S rRNA gene sequencing analysis which revealed that they were 99% identical with Aeromonas jandaei. The bacterial isolates were further characterized using biochemical methods. The lowest bacterial dose which caused 50% cumulative mortality (LD50) in Pangasianodon hypophthalmus was 8.84 X 105 CFU per fish. This was achieved by injecting the fish intraperitoneally with pure culture of A.jandaei isolated from diseased fish. Histopathogical studies revealed necrosis hemorrhaging, and other cellular alterations of different tissues of collected organs viz. gill, liver, and kidney of P. hypophthalmus, observed with the diseased conditions