Diltiazem Inhibits Coronary Spasm via Inhibition of Cav1.2Phosphorylation and Protein Kinase C Activation in a Mouse Model of Coronary Spastic Angina.

Calcium antagonists are used for coronary spastic angina (CSA) treatment. We previously identified a phospholipase C (PLC) -δ1 gene variant that results in enhanced PLC activity in patients with CSA and developed a CSA animal model by generating vascular smooth muscle cell-specific human variant PLC-δ1 overexpression (PLC-TG) mice. In this study, we investigated the molecular mechanism of CSA using the PLC-TG mice and the inhibitory effect of a calcium antagonist, diltiazem hydrochloride (DL).We treated the PLC-TG and wild-type (WT) mice with oral DL or trichlormethiazide (TM) (control) for 2 weeks. Ergometrine injection-induced coronary spasm was observed on the electrocardiogram in all 5 PLC-TG mice treated with TM, but only in 1 of 5 PLC-TG mice treated with DL. Voltage-dependent calcium channel (Cav1.2) phosphorylation and protein kinase C (PKC) activity were enhanced in the aortas of PLC-TG mice treated with TM. DL treatment significantly inhibited Cav1.2 phosphorylation and PKC activity. Although total Cav1.2 expression was similar between WT and PLC-TG mice treated with TM, DL treatment significantly increased its expression in PLC-TG mice. Furthermore, its expression remained high after DL discontinuation. DL and PKC inhibitor suppressed intracellular calcium response to acetylcholine in cultured rat aortic smooth muscle cells transfected with variant PLC-δ1.These results indicate that enhanced PLC activity causes coronary spasm, presumably via enhanced Cav1.2 phosphorylation and PKC activity, both of which were inhibited by DL. Enhanced total Cav1.2 expression after DL discontinuation and high PKC activity may be an important mechanism underlying the calcium antagonist withdrawal syndrome.

Safety and efficacy of contemporary catheter ablation for atrial fibrillation patients with a history of cardioembolic stroke in the era of direct oral anticoagulants.

BACKGROUND: The safety and efficacy of the contemporary atrial fibrillation (AF) ablation in patients with a recent or previous history of cardioembolic stroke (CS) or transient ischemic attack (TIA) remain to be established. METHODS: A total of 447 patients who underwent first-ever contact force (CF)-guided AF ablation with circumferential pulmonary vein isolation were included. Of these, 17 had CS or TIA within 6 months before ablation (Group 1), 30 more than 6 months before ablation (Group 2), and the other 400 without CS or TIA (Group 3). Procedural complications and recurrence of AF and atrial tachyarrhythmias were compared among the 3 groups. RESULTS: The mean age was 71±7, 66±9, and 61±11 years in Groups 1, 2, and 3, respectively (p<0.05, Group 1 versus Group 3). The oral anticoagulants were warfarin (n=108, 24.1%), dabigatran (n=101, 22.6%), rivaroxaban (n=147, 32.9%), apixaban (n=87, 19.5%), and edoxaban (n=4, 0.9%), and did not differ among the 3 groups. Median follow-up period was 14 [IQR 12-22], 13 [12-14], and 12 [10-16] months, respectively. One episode of cardiac tamponade, 2 episodes of arteriovenous fistula, and some minor complications occurred in Group 3, but no complications occurred in Groups 1 and 2 in the periprocedural period. Although one episode of CS occurred 11 days after the procedure in Group 3, there were no periprocedural CS, TIA, or major bleedings in Groups 1 and 2. AF recurrence-free rate after the procedure was 76.5%, 86.7%, and 79.1% in Groups 1, 2, and 3, respectively, and there was no difference in Kaplan-Meier curves among the 3 groups. CONCLUSION: The safety and efficacy of CF-guided AF ablation in the era of direct oral anticoagulants in patients with a recent or previous history of CS or TIA are similar to those in patients without it.

Long Postpacing Interval After Entrainment of Tachycardia Including a Slow Conduction Zone Within the Circuit.

BACKGROUNDS: Postpacing interval (PPI) measured after entrainment pacing describes the distance between pacing site and reentrant circuit. However, the influential features to PPI remain to be elucidated. METHODS AND RESULTS: This study included 22 cases with slow/fast atrioventricular (AV) nodal reentrant tachycardia (AVNRT), 14 orthodromic AV reciprocating tachycardia (AVRT) using an accessary pathway, 22 typical atrial flutter (AFL), and 18 other macroreentrant atrial tachycardia (atypical AFL). Rapid pacing at a pacing cycle length (PCL) 5% shorter than tachycardia cycle length (TCL) was done from a site on or close to the reentry circuit. Pacing sites included the coronary sinus ostium in AVNRT, earliest atrial activation site in AVRT, and cavotricuspid isthmus in typical AFL. In atypical AFL, tachycardia circuit was determined on the basis of CARTO mapping, and then the pacing site was. TCL was significantly longer in AVNRT and AVRT than in typical AFL and atypical AFL (both P < 0.05). PCL minus TCL value was similar among the 4 groups. PPI minus TCL value (milliseconds) was significantly longer in AVNRT (median, 40 [IQR, 29-60.8]) and AVRT (34 [20-47]) than in typical AFL (0 [0-4]) and atypical AFL (3.5 [0-8]) (both P < 0.05). Furthermore, PPI minus TCL was prolonged with shortening of PCL in AVNRT and AVRT (both P < 0.05), whereas it was unchanged in typical AFL (P = 0.50). CONCLUSION: PPI after concealed entrainment is prolonged compared with TCL when the reentry circuit involves a slow conduction zone with a decremental conduction property such as the AV node.

Multicenter study on the long-term (3-year) efficacy of lanthanum carbonate in dialysis patients.

We previously conducted a multicenter study enrolling 101 dialysis patients with hyperphosphatemia in which lanthanum carbonate (LC) was administered for 2 years. In this study, the administration has been continued for an additional year, and we have evaluated the long-term (a total of 3 years) effects of LC. The average serum phosphorus (P) level was 6.05 mg/dL at the start and decreased to 5.84 mg/dL after 3 years, but no significant differences were observed at both points. The average serum corrected calcium (Ca) level significantly reduced after 3 years (P < 0.001). As results of evaluating the achievement rates with the management target values of serum P, Ca and intact parathyroid hormone (PTH) stated in the Japanese guideline, the achievement rates increased after 3 years. From these results, LC is considered to be a useful P binder that can be used for long-term treatment of hyperphosphatemia, without causing a Ca load.

High correlation of estimated local conduction velocity with natural logarithm of bipolar electrogram amplitude in the reentry circuit of atrial flutter.

BACKGROUND: Low conduction velocity (CV) in the area showing low electrogram amplitude (EA) is characteristic of reentry circuit of atypical atrial flutter (AFL). The quantitative relationship between CV and EA remains unclear. We characterized AFL reentry circuit in the right atrium (RA), focusing on the relationship between local CV and bipolar EA on the circuit. METHODS AND RESULTS: We investigated 26 RA AFL (10 with typical AFL; 10 atypical incisional AFL; 6 atypical nonincisional AFL) using CARTO system. By referring to isochronal and propagation maps delineated during AFL, points activated faster on the circuit were selected (median, 7 per circuit). At the 196 selected points obtained from all patients, local CV measured between the adjacent points and bipolar EA were analyzed. There was a highly significant correlation between local CV and natural logarithm of EA (lnEA) (R(2) = 0.809, P < 0.001). Among 26 AFL, linear regression analysis of mean CV, calculated by dividing circuit length (152.3 ± 41.7 mm) by tachycardia cycle length (TCL) (median 246 msec), and mean lnEA, calculated by dividing area under curve of lnEA during one tachycardia cycle by TCL, showed y = 0.695 + 0.191x (where: y = mean CV, x = lnEA; R(2) = 0.993, P < 0.001). Local CV estimated from EA with the use of this formula showed a highly significant linear correlation with that measured by the map (R(2) = 0.809, P < 0.001). CONCLUSION: The lnEA and estimated local CV show a highly positive linear correlation. CV is possibly estimated by EA measured by CARTO mapping.

Performance evaluation of laboratory scale up-flow constructed wetlands with different designs and emergent plants.

The objective of present study was to assess the simultaneous removal of organic pollutants and nutrients by five laboratory scale up-flow constructed wetlands (UFCWs). Aerobic and anaerobic regions were well developed at the upper and lower beds, respectively, in the UFCW reactors with supplementary aeration. The emergent plants employed were Phragmites australis and Manchurian wild rice. The COD, T-N, T-P, NH(4)-N and NO(3)-N removal efficiencies for the UFCW reactors were in the range of 90-94%, 69-92%, 29-52%, 59-98% and 45-100%, respectively. The organic matter and NH(4)-N removal efficiencies in the aerated wetland reactors were better than the non-aerated wetland reactors. The supplementary aeration has enhanced the aerobic biodegradation of organic matter and nitrification. The Manchurian wild rice outperformed P. australis in the removals of T-P, T-N and NH(4)-N.

Characterization of histone lysine-specific demethylase in relation to thyroid hormone-regulated anuran metamorphosis.

The thyroid hormone receptor (THR) is a member of the nuclear transcription factor and plays a central role in regulating anuran metamorphosis. Previous studies with mammalian cells have suggested that THR is involved in chromatin remodeling through histone methylation. In the present study, we cloned cDNA of lysine-specific demethylase gene, xLSD1, from Xenopus laevis and examined its expression in relation to metamorphosis. Overexpression of xLSD1 in A6 cells, a Xenopus laevis cell line, resulted in the decrease of methylation status of lysine residues of histone H3, indicating that the protein of cloned xLSD1 was functionally active. The expression of LSD1 at mRNA levels was up-regulated in the body skin and the intestine during natural and thyroid hormone-induced metamorphosis. Larval epidermal basal cells and intestinal epithelial cells at the premetamorphic stage were identified as the xLSD1-expressing cells. At the metamorphic climax stage the progenitor cells of adult epidermal basal cells also expressed xLSD1, whereas those of the adult intestinal epithelial cells did not. We propose that LSD1 participates in the regulation of metamorphosis through THR- or another transcriptional factor-induced chromatin remodeling.

The influence of dialysate calcium on the therapeutic effects of sevelamer hydrochloride in hemodialysis patients with secondary hyperparathyroidism under treatment of intravenous vitamin d metabolites.

The management of hyperphosphatemia is essential to treat secondary hyperparathyroidism and to prevent ectopic calcification. Sevelamer hydrochloride (sevelamer), a new phosphate binder that contains neither aluminum nor calcium, which could be theoretically beneficial for the management of hyperphosphatemia in dialysis patients with secondary hyperparathyroidism who are receiving intravenous vitamin D metabolites (maxacalcitol or calcitriol). To reduce calcium loads, a dialysate calcium concentration of 2.5 mEq/L is recommended by Kidney Disease Outcome Quality Initiative (K/DOQI) guidelines. In Japan, a dialysate calcium concentration of 3.0 mEq/L prevails. We investigated the influence of dialysate calcium on the therapeutic effect of sevelamer in 40 hemodialysis patients who are under treatment of intravenous vitamin D metabolites for secondary hyperparathyroidism (VD(+)) and compared the results with those of 41 patients who had not received vitamin D metabolites (VD(-)). Serum phosphorus and calcium-phosphorus products showed no significant change by sevelamer in either the VD(+) subgroup of patients receiving hemodialysis with dialysate calcium of 2.5 mEq/L (DCa2.5) or those receiving hemodialysis with dialysate calcium of 3.0 mEq/L (DCa3.0), while serum phosphorus and calcium-phosphorus products decreased in both the VD(-) subgroups. Serum calcium decreased in the DCa2.5 subgroup and did not change in the DCa3.0 subgroup in both the VD(+) and the VD(-) subjects. Parathyroid hormone and alkaline phosphatase increased in the DCa2.5 subgroup and did not change in the Ca 3.0 subgroup in the VD(+) subjects. Serum calcium decreased in both subgroups in the VD(-) subjects. Parathyroid hormone obtained after sevelamer administration in the VD(-) group was within the target range of the K/DOQI guidelines. In conclusion, the concomitant use of sevelamer as a phosphate binder and the dialysate of calcium concentration of 2.5 mEq/L have possibilities for worsening secondary hyperparathyroidism in patients receiving intravenous vitamin D.

Accumulation of maize response regulator proteins in mesophyll cells after cytokinin treatment.

The maize response regulator genes ZmRR1 and ZmRR2 respond to cytokinin, and the translated products seem to be involved in nitrogen signal transduction mediated by cytokinin through the His-Asp phosphorelay. To elucidate the physiological function of the proteins, we examined the temporal and spatial distribution in maize leaves by immunochemical analysis and use of transgenic plants. ZmRR1 and ZmRR2 polypeptides could be distinctively detected by western blotting. The polypeptides accumulated in leaves within 5 h of the supply of nitrate to nitrogen-depleted maize, and the accumulation was transient. The extent of induction was larger in the leaf tip, which is rich in photosynthetically matured cells, than elsewhere. In leaves, the polypeptides accumulated mostly in mesophyll cells. Histochemical analyses of transgenic maize harboring a ZmRR1 promoter-beta-glucuronidase fusion gene also showed most of the expression to be in these cells. These results suggest that ZmRR1 and ZmRR2 are induced in mesophyll cells and function in nitrogen signal transduction mediated by cytokinin.