Astrocytes release various bioactive substances via Ca(2+) - and soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE)-dependent exocytosis; however the regulatory mechanisms of glial exocytosis are still poorly understood. In the present study, we investigated the effect of protein kinase C (PKC) on exocytosis in glial cells using primary cultured astrocytes and clonal rat glioma C6 cells. Mass spectrometry and Western blot analysis using phospho-specific antibodies revealed that phorbol 12-myristate 13-acetate (PMA) treatment induced the phosphorylation of synaptosomal-associated protein of 23 kDa (SNAP-23) on Ser(95), Ser(120), and Ser(160) in cultured astrocytes and C6 cells. Phosphorylation at these sites was suppressed by treatment with the PKC inhibitor, bisindolylmaleimide I (BIS). In contrast, Ser(110) of SNAP-23 was constitutively phosphorylated in these cells and was dephosphorylated in a PKC-dependent manner. Exogenously expressed human growth hormone (hGH) accumulated in cytoplasmic granular structures in cultured astrocytes, and its release after ATP-treatment was Ca(2+) - and SNARE-dependent. PMA treatment suppressed the ATP-induced hGH release from astrocytes and this inhibition was reversed by BIS. We also observed PMA-dependent suppression and an attenuation of that suppression by BIS in ionomycin-induced hGH release from C6 cells. These results suggest that intracellular activation of PKC suppresses Ca(2+) - and SNARE-dependent exocytosis in astroglial cells.

Background: Post-pulmonary embolism (PE) syndrome is an important clinical condition that can affect the long-term prognosis after acute PE. Objective:We aimed to evaluate the prevalence of residual pulmonary thrombi and the thrombotic burden 1 year after acute PE, by using our refined computed tomography (CT) imaging method.Patients/Methods: In this prospective study, patients diagnosed with acute PE were recruited and examinations were conducted at 1 month, 6 months, and 1 year.Especially at 1 year, patients were evaluated multifacetedly, including by laboratory tests, quality-of-life, 6-min walking test, and enhanced CT.Results: Fifty-two patients were enrolled. Two patients (3.8%) developed chronic thromboembolic pulmonary hypertension. A total of 43 patients completed evaluation at 1 year, among whom (74%) had residual thrombi, with a median modified CT obstruction index (mCTOI) of 10.7%. In multivariate analysis, residual thrombi at 1 month was the only factor significantly related to residual thrombi at 1 year (odds ratio, 103.4; 95% confidence interval, 4.2-2542.1). The tricuspid regurgitation pressure gradient ≥60 mmHg and left ventricular end-diastolic dimension at diagnosis were significantly related to mCTOI at 1 year (β = 0.367, P = .003; and β = -0.435, P = .001, respectively). Conclusions:Using our improved CT imaging protocol, we found a high prevalence of residual thrombi 1 year after acute PE. Furthermore, right ventricular overload was related to the thrombotic burden. The long-term treatment strategy of acute PE could be modified to include precise CT imaging.

Background Left atrial (LA) conduction velocity (CV) is an electrical remodeling parameter of atrial fibrillation (AF) substrate. However, the pathophysiological substrate of LA-CV and its impact on outcomes after catheter ablation for AF have not been well evaluated. Methods We retrospectively evaluated 119 patients with AF who underwent catheter ablation and electroanatomical mapping during sinus rhythm. To measure regional LA-CV, we took triplet sites (A, B, and C) on the activation map and calculated the magnitude of the matched orthogonal projection vector between vector-AB and vector-AC, indicating two-dimensional CV. The median of the LA-CVs from four triad sites in both the anterior and posterior walls was set as the ‘model LA-CV’. We evaluated the impact of the model LA-CV on recurrence after ablation and relationship between the model LA-CV and LA-low voltage area (LVA) of < 0.5 mV. Results During the 12-month follow-up, 29 patients experienced recurrence. The LA-CV model was significantly correlated with ipsilateral LVA. The lower anterior model LA-CV was significantly associated with recurrence, with the cut-off value of 0.80 m/s having a sensitivity of 72% and specificity of 67%. Multivariable analysis revealed that the anterior model LA-CV (hazard ratio, 0.09; 95% confidence interval, 0.01–0.94; p = 0.043) and anterior LA-LVA (hazard ratio, 1.06; 95% confidence interval, 1.00–1.11; p = 0.033) were independently associated with AF recurrence. The anterior LA-LVA was mildly correlated with the anterior model LA-CV (r = -0.358; p < 0.001), and patients with both lower LA-CV and greater anterior LA-LVA based on each cut-off value had the worst prognosis. However, decreased LA-CV was more likely to be affected by the distribution pattern of the LVA rather than the total size of the LVA. Conclusion Decreased anterior LA-CV was a significant predictor of AF recurrence and was a useful electrical parameter in addition to LA-LVA for estimating AF arrhythmogenicity.

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