A cross-sectional study on clinico-dermoscopic features of periorbital melanosis in a tertiary care hospital.

INTRODUCTION: Periorbital melanosis (POM) is an esthetic facial concern on increasing trend and has a severe emotional impact on patients. We aimed to study the clinical and dermoscopic patterns of periorbital melanosis to aid in the classification and strategize therapy. METHODS: A cross-sectional, observational study was conducted on one hundred patients with POM in a tertiary care center in India from January 2020-March 2020. Dermoscopic assessment of POM was done using video dermatoscope- FotoFinder Medicam 1000s (magnification up to 140x). RESULTS: The mean age of participants was 32.8 ± 9 years. It was more prevalent among females (78%). The constitutional type (43%) of POM was the most common followed by shadow-effect type (32%). The various dermoscopic pigmentary patterns seen were scattered pigmented dots (56%), exaggerated pigment network (31%), globules (30%), and blotches (27%). Dilated veins and telangiectasia were seen in 50% and 32% of subjects, respectively. Exaggerated skin markings were seen in 43% of participants. Scattered pigmented dots were most commonly seen in constitutional, vascular, and shadow types but were significantly associated with vascular type. Exaggerated pigment network was the most frequent pigmentary pattern in post-inflammatory type of POM. Globules were significantly associated with constitutional as well as shadow type of POM and blotches with shadow type of POM. CONCLUSIONS: Periorbital melanosis presents as multifactorial entity with constitutional type being the most common. The dermoscopic patterns of POM may provide a clue to the underlying etiology, thereby helping to plan appropriate treatment.

Ouabain stimulates protein kinase B (Akt) phosphorylation in opossum kidney proximal tubule cells through an ERK-dependent pathway.

Endogenous cardiotonic glycosides bind to the inhibitory binding site of the plasma membrane sodium pump (Na(+)/K(+)-ATPase). Plasma levels of endogenous cardiotonic glycosides increase in several disease states, such as essential hypertension and uremia. Low concentrations of ouabain, which do not inhibit Na(+)/K(+)-ATPase, induce cell proliferation. The mechanisms of ouabain-mediated response remain unclear. Recently, we demonstrated that in opossum kidney (OK) proximal tubular cells, low concentrations of ouabain induce cell proliferation through phosphorylation of protein kinase B (Akt) in a calcium-dependent manner. In the present study, we identified ERK as an upstream kinase regulating Akt activation in ouabain-stimulated cells. Furthermore, we provide evidence that low concentrations of ouabain stimulate Na(+)/K(+)-ATPase-mediated (86)Rb uptake in an Akt-, ERK-, and Src kinase-dependent manner. Ouabain-mediated ERK phosphorylation was inhibited by blockade of intracellular calcium release, calcium entry, tyrosine kinases, and phospholipase C. Pharmacological inhibition of phosphoinositide-3 kinase and Akt failed to inhibit ouabain-stimulated ERK phosphorylation. Ouabain-mediated Akt phosphorylation was inhibited by U0126, a MEK/ERK inhibitor, suggesting that ouabain-mediated Akt phosphorylation is dependent on ERK. In an in vitro kinase assay, active recombinant ERK phosphorylated recombinant Akt on Ser(473). Moreover, transient transfection with constitutively active MEK1, an upstream regulator of ERK, increased Akt phosphorylation and activation, whereas overexpression of constitutively active Akt failed to stimulate ERK phosphorylation. Ouabain at low concentrations also promoted cell proliferation in an ERK-dependent manner. These findings suggest that ouabain-stimulated ERK phosphorylation is required for Akt phosphorylation on Ser(473), cell proliferation, and stimulation of Na(+)/K(+)-ATPase-mediated (86)Rb uptake in OK cells.

Ouabain induces cell proliferation through calcium-dependent phosphorylation of Akt (protein kinase B) in opossum kidney proximal tubule cells.

Cardiotonic glycosides, like ouabain, inhibit Na(+)-K(+)-ATPase. Recent evidence suggests that low molar concentrations of ouabain alter cell growth. Studies were conducted to examine the effect of ouabain on Akt phosphorylation and rate of cell proliferation in opossum kidney (OK) proximal tubule cells. Cells exposed to 10 nM ouabain displayed increased Akt Ser(473) phosphorylation, as evidenced by an increase in phospho-Akt Ser(473) band density. Ouabain-stimulated Akt Ser(473) phosphorylation was inhibited by pretreatment with phosphatidylinositol 3-kinase (PI3K) inhibitors (LY294002 and wortmannin), a PLC inhibitor (edelfosine), and an Akt inhibitor. Moreover, ouabain-mediated Akt Ser(473) phosphorylation was suppressed by reduction of extracellular calcium (EGTA) or when intracellular calcium was buffered by BAPTA-AM. An inhibitor of calcium store release (TMB-8) and an inhibitor of calcium entry via store-operated calcium channels (SKF96365) also suppressed ouabain-mediated Akt Ser(473) phosphorylation. In fura-2 AM-loaded cells, 10 nM ouabain increased capacitative calcium entry (CCE). Ouabain at 10 nM did not significantly alter baseline cytoplasmic calcium concentration in control cells. However, treatment with 10 nM ouabain caused a significantly higher ATP-mediated calcium store release. After 24 h, 10 nM ouabain increased the rate of cell proliferation. The Akt inhibitor, BAPTA-AM, SKF96365, and cyclopiazonic acid suppressed the increase in the rate of cell proliferation caused by 10 nM ouabain. Ouabain at 10 nM caused a detectable increase in (86)Rb uptake but did not significantly alter Na(+)-K(+)-ATPase (ouabain-sensitive pNPPase) activity in crude membranes or cell sodium content. Taken together, the results point to a role for CCE and Akt phosphorylation, in response to low concentrations of ouabain, that increase the rate of cell proliferation without inhibiting Na(+)-K(+)-ATPase-mediated ion transport.