Mast cell mediators in relation to dengue severity: A systematic review and meta-analysis.

BACKGROUND: Degranulation of mast cells (MCs) releases several mediators such as vascular endothelial growth factor (VEGF), chymase, tryptase, histamine, and cytokines, which all have important roles in the severity of dengue infection. We aimed to investigate the role of MCs in severity of dengue. METHODS: We searched for relevant studies in 10 databases on 15 August 2016. Meta-analysis (MA) was conducted by R version 3.5.0. RESULTS: We included 24 studies. in vivo and in vitro studies showed higher MC products released from infected mice/cells with dengue virus. In addition, when administering MC stabilizers or antihistaminic drugs, there was a decrease in vascular/capillary permeability. In human and at early stages, studies revealed an insignificant difference in VEGF levels in dengue fever (DF) versus dengue hemorrhagic fever (DHF) (standardized mean difference [SMD] 0.145; 95% confidence interval [CI], -0.348-0.638). Meanwhile, at acute stages and compared with healthy controls, high heterogeneity with an inconclusive difference in VEGF levels were noted in DF and DHF. However, pooled serum and plasma levels of VEGF were increased significantly in dengue shock syndrome (DSS) versus healthy controls (SMD 0.65; 95% CI, 0.3-0.95). There were also significantly higher chymase levels in DHF patients compared with DF during the acute phase (MD -6.531; 95% CI, -12.2 to -0.9). CONCLUSION: VEGF and chymase levels are mediators in dengue pathogenesis. However, limited data were available to support their role in severe dengue cases. Further studies are needed to evaluate the function of other mediators in dengue severity.

Isolated adult congenital uni-leaflet severe mitral valve stenosis, a case report, and review of literature.

Reported cases of uni-leaflet mitral valve (MV) were related to the absence or dysplasia of the posterior mitral leaflet with ample anterior mitral leaflet. We present here a new entity of uni-leaflet MV where the MV appears as a membrane-like structure with a single slit-like orifice at its lateral part with no commissures. CASE REPORT: Continuous Doppler flow revealed a mean pressure gradient of 19 mmHg across the mitral valve indicating severe mitral stenosis. In 3D images from the left atrial view, the MV appeared like a membrane with a single orifice in its lateral part toward the left atrial appendage, the area of this orifice by 3D was 0.52 cm2, there were no commissures or even any residual lines at the site where commissures should be. The diagnosis of congenital severe mitral stenosis due to acommissural MV was confirmed. During surgery, the surgical appearance of the MV confirmed our diagnosis by 3D. CONCLUSION: Isolated congenital severe mitral stenosis presenting in adulthood is rare, uni-leaflet MV as a cause is only reported in a few cases. MV replacement is usually indicated due to the abnormal anatomy of MV leaflets and the subvalvular apparatus..