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Konstantinos Tzelepis

Publications and source records attributed to Konstantinos Tzelepis.

2 recordsLinked to original sources

Giant Hydronephrosis Secondary to Ureteral Obstruction Imposed by Massive Hepatomegaly in a Patient with Polycystic Liver Disease: A Case Report.

BACKGROUND: Polycystic liver disease is a genetic pathology characterized by the formation of numerous cysts in the liver. This case is notable for the rare presentation of isolated polycystic liver disease leading to secondary obstructive uropathy. Unlike the more common association with autosomal dominant polycystic kidney disease, this patient exhibited no evidence of bilateral polycystic kidney disease; the only renal finding was a solitary simple cyst in the contralateral kidney, considered an incidental finding, highlighting an unusual extrinsic mechanism of urinary tract obstruction due to massive hepatomegaly. In adults, polycystic liver disease often manifests as an extra-renal complication of autosomal dominant polycystic kidney disease. In rare cases, however, it may present solely as autosomal dominant polycystic liver disease without renal involvement. CASE PRESENTATION: In this study, we describe a patient with isolated polycystic liver disease, in whom marked hepatomegaly progressively compressed and displaced the kidney, obstructing the ureter at the pyeloureteral junction. Imaging studies, including abdominal ultrasound and computed tomography, confirmed the extent of cystic involvement and the resulting mass effect. This led to the gradual development of severe hydronephrosis, evident both on palpation and during clinical examination of the abdomen. Hydronephrosis, in turn, exerted pressure on adjacent organs such as the liver, pancreas, stomach, and large vessels, causing symptoms including abdominal distension, dysphagia, gastroesophageal reflux, early satiety, reduced mobility, as well as abdominal and lumbar pain. CONCLUSION: Clinicians should consider the possibility of mass effect complications in patients with isolated polycystic liver disease, as early recognition and intervention may help prevent severe secondary organ dysfunction.

Hydronephrosis

GlycoRNA complexed with heparan sulfate regulates VEGF-A signalling.

Heparan sulfate proteoglycans (HSPGs) have been recognized as key plasma membrane-tethered co-receptors for a broad range of growth factors and cytokines containing cationic heparan-binding domains1,2. However, how HSPGs mechanistically mediate signalling at the cell surface-particularly in the context of cell surface RNA-remain poorly understood. During developmental and disease processes, vascular endothelial growth factor (VEGF-A), a heparan sulfate-binding factor, regulates endothelial cell growth and angiogenesis3. The regulatory paradigm for endothelial cell-mediated selectively of VEGF-A binding and activity has largely been focused on understanding the selective sulfation of the anionic heparan sulfate chains4-8. Here we examine the organizational rules of a new class of anionic cell surface conjugates, glycoRNAs9,10, and cell surface RNA-binding proteins (csRBPs11,12). Leveraging genome-scale knockout screens, we discovered that heparan sulfate biosynthesis and specifically the 6-O-sulfated forms of heparan sulfate chains are critical for the assembly of clusters of glycoRNAs and csRBPs (cell surface ribonucleoproteins (csRNPs)). Mechanistically, we show that these clusters antagonize heparan sulfate-mediated activation of ERK signalling downstream of VEGF-A. We demonstrate that the heparan sulfate-binding domain of VEGF-A165 is responsible for binding RNA, and that disrupting this interaction enhances ERK signalling and impairs vascular development both in vitro and in vivo and is conserved across species. Our study thus uncovers a previously unrecognized regulatory axis by which csRNPs negatively modulate heparan sulfate-mediated signalling in the context of angiogenesis driven by VEGF-A.

Heparan Sulfate