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The utility of the VecTest antigen-capture assay to detect West Nile virus (WNV) in field-collected dead corvids was evaluated in Manitoba and Ontario, Canada, in 2001 and 2002. Swabs were taken from the oropharynx, cloaca, or both of 109 American Crows, 31 Blue Jays, 6 Common Ravens, and 4 Black-billed Magpies from Manitoba, and 255 American Crows and 28 Blue Jays from Ontario. The sensitivity and specificity of the antigen-capture assay were greatest for samples from American Crows; oropharyngeal swabs were more sensitive than cloacal swabs, and interlaboratory variation in the results was minimal. The sensitivity and specificity of the VecTest using oropharyngeal swabs from crows were 83.9% and 93.6%, respectively, for Manitoba samples and 83.3% and 95.8%, respectively, for Ontario birds. The VecTest antigen-capture assay on oropharyngeal secretions from crows is a reliable and rapid diagnostic test that appears suitable for incorporation into a WNV surveillance program.

We have previously shown that non-myocytes present in healed 8-week infarct scar overexpress transduction proteins required for initiating the elevated deposition of structural matrix proteins in this tissue. Other work suggests that TGF-beta 1 may be involved in cardiac fibrosis and myocyte hypertrophy. However, the significance of the altered TGF-beta signaling in heart failure in the chronic phase of post-myocardial infarction (MI), particularly in the ongoing remodeling of the infarct scar, remains unexplored. Patterns of cardiac TGF beta 1 and Smad 2, 3, and 4 protein expression were investigated 8 weeks after MI and were compared to relative collagen deposition in border tissues (containing remnent myocytes) and the infarct scar (non-myocytes). Both TGF-beta 1 mRNA abundance and protein levels were significantly increased in the infarct scar v control values, and this trend was positively correlated to increased collagen type I expression. Cardiac Smad 2, 3, and 4 proteins were significantly increased in border and scar tissues v control values. Immunofluorescent studies indicated that Smad proteins localized proximal to the cellular nuclei present in the infarct scar. Decorin mRNA abundance was elevated in border and infarct scar, and the pattern of decorin immunostaining was markedly altered in remote remnant heart and scar v staining patterns of control sections. Expression of T beta RI (53 kDa) protein was significantly reduced in the scar, while the 75 kDa and 110 kDa isoforms of T beta RII were unchanged and significantly increased in scar, respectively. These results indicate that TGF-beta/Smad signaling may be involved in the remodeling of the infarct scar after the completion of wound healing per se, via ongoing stimulation of matrix deposition.

Recent studies have implicated angiotensin II (angiotensin) in the pathogenesis of cardiac hypertrophy and heart failure. Heart failure is associated with alterations in intracellular Ca2+ movements mediated by sarcolemmal (SL) and sarcoplasmic reticular (SR) membranes in cardiac myocytes. As it was suspected that alteration gene expression of proteins responsible for controlling transmembrane Ca2+ fluxes may contribute to loss of Ca2+ homeostasis in failing hearts, we undertook a study of the effect of angiotensin on the expression of some target genes in the myocardium. Specifically, we tested the effect of angiotensin on mRNA abundance of cardiac Ca(2+)-transport genes including SL Na+/Ca2+ exchange (EX), SR ryanodine receptor (RYR), and sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA). The mRNA abundance of target gene was assessed by Northern blot assay in (i) direct hormonal stimulation of cultured isolated neonatal and adult rat myocytes and (ii) adult rat hearts after implantation of osmotic mini-pumps for delivery of hormone. In all experiments, Northern blot data were normalized using cDNA (Glyceraldehyde 3-phosphate dehydrogenase signal, GAPDH) hybridization to RNA samples. The results indicate that the ratios of EX/GAPDH, RYR/GAPDH, and SERCA2/GAPDH signals were decreased by 51.6%, 55.0%, and 49.4% respectively after neonatal cardiac myocytes were treated (24 h) with 10(-7) M angiotensin. These decreases were blocked completely by treatment with angiotensin subtype 1 (AT1) receptor antagonist (losartan), whereas angiotensin subtype 2 (AT2) receptor antagonist (PD123319) treatment had no effect on the angiotensin-mediated decrease in target gene mRNA abundance. In contrast, angiotensin had no effect on EX, RYR nor SERCA2 gene mRNA abundance in cultured adult myocytes. In a separate series of experiments wherein adult male Sprague-Dawley rats were infused with different dose of angiotensin for 3 days via osmotic mini-pump, we did not detect any alterations in mRNA abundance of cardiac EX/GAPDH, RYR/GAPDH or SERCA/GAPDH genes in either left or right ventricular samples. Thus our results indicate that, in neonatal rat myocytes, angiotensin affects SL and SR calcium transport gene expression by direct agonism of AT1-receptors. As the infusion of low and high dose angiotensin did not affect the expression of target genes in adult hearts, we suggest that the mechanisms for transduction of the angiotensin signaling in neonatal and adult myocytes may be different and may depend on the stage of development. We conclude that regulation of myocardial Ca(2+)-transport gene mRNA abundance by angiotensin may differ among neonatal and adult animals. Nonetheless, our finding with respect to neonatal preparation led us to believe that in neonatal myocytes, the mRNA abundance of SL Na+/Ca2+ exchange, SR ryanodine receptor, and SR Ca(2+)-ATPase are all decreased in response to stimulation by angiotensin.

We have previously shown that myofibroblasts of the healed 8 week infarct scar overexpress transduction proteins that may be linked to elevated deposition of extracellular matrix components in this tissue. Other work suggests that TGFβ1, may be involved in cardiac fibrosis and myocyte hypertrophy. The significance of the altered TGFβ signaling in heart failure in the chronic phase of post-myocardial infarction (MI), particularly in the ongoing remodeling of the infarct scar, remains unexplored. Patterns of cardiac TGFβ1 and Smad 2, 3, and 4 protein expression were investigated 8 weeks after MI and were compared to relative collagen deposition in border tissues (containing remnant myocytes) and the infarct scar (nonmyocytes dominated by myofibroblasts). Both TGFβ1 mRNA abundance (Northern analysis) and protein levels (ELISA) were significantly increased in the infarct scar versus control values, and this trend was positively correlated to increased collagen type I expression in this tissues. Cardiac Smad 2, 3, and 4 proteins were significantly increased in border and scar tissues versus control values. Immunofluorescent studies indicated that Smad proteins were proximally localized to cellular nuclei in the infarct scar. TβRI (53 kDa) protein expression was significantly reduced in the scar, while the 75kDa and 110kDa isoforms of TβRII were unchanged and significantly increased respectively, in the infarct scar. These results indicate that TGFβ/Smad signaling may be involved in the remodeling of the infarct scar after the completion of wound healing per se, via ongoing stimulation of matrix deposition.