[Impact of late sodium current inhibition on cardiac electrophysiology parameters and ventricular arrhythmias in isolated Langendorff perfused rabbit hearts with short QT interval].

Objective: To determine the electrophysiological effects and related mechanisms of late sodium current inhibitors on hearts with short QT intervals. Methods: The electrophysiological study was performed on isolated Langendorff perfused rabbit hearts. A total of 80 New Zealand White rabbits were used and 34 hearts without drug treatment were defined as control group A, these hearts were then treated with IKATP opener pinacidil, defined as pinacidil group A. Then, 27 hearts from pinacidil group A were selected to receive combined perfusion with sodium channel inhibitors or quinidine, a traditional drug used to treat short QT syndrome, including ranolazine combined group (n=9), mexiletine combined group (n=9), and quinidine combined group (n=9). Nineteen out of the remaining 46 New Zealand rabbits were selected as control group B (no drug treatments, n=19), and then treated with pinacidil, defined as pinacidil group B (n=19). The remaining 27 rabbits were treated with sodium inhibitors or quinidine alone, including ranolazine alone group (n=9), mexiletine alone group (n=9), and quinidine alone group (n=9). Electrocardiogram (ECG) physiological parameters of control group A and pinacidil group A were collected. In control group B and pinacidil group B, programmed electrical stimulation was used to induce ventricular arrhythmias and ECG was collected. ECG physiological parameters and ventricular arrhythmia status of various groups were analyzed. The concentrations of pinacidil, ranolazine, mexiletine and quinidine used in this study were 30, 10, 30 and 1 µmol/L, respectively. Results: Compared with control group A, the QT interval, 90% of the repolarization in epicardial and endocardial monophasic action potential duration (MAPD90-Epi, MAPD90-Endo) was shortened, the transmural dispersion of repolarization (TDR) was increased, and the effective refractor period (ERP) and post-repolarization refractoriness (PRR) were reduced in pinacidil group A (all P<0.05). Compared with the pinacidil group A, MAPD90-Epi, MAPD90-Endo, QT interval changes were reversed in quinidine combined group and mexiletine combined group (all P<0.05), but not in ranolazine combined group. All these three drugs reversed the pinacidil-induced increases of TDR and the decreases of ERP and PRR. The induced ventricular arrhythmia rate was 0 in control group B, and increased to 10/19 (χ2=13.6, P<0.05) in pinacidil group B during programmed electrical stimulation. Compared with the pinacidil group B, incidences of ventricular arrhythmia decreased to 11% (1/9), 11% (1/9) and 0 (0/9) (χ2=4.5, 4.5, 7.4, P<0.05) respectively in ranolazine group, mexiletine group and quinidine group. Conclusions: Inhibition of late sodium current does not increase but even decreases the risk of malignant arrhythmia in hearts with a shortened QT interval. The antiarrhythmic mechanism might be associated with the reversal of the increase of TDR and the decrease of refractoriness (including both ERP and PRR) of hearts with shortened QT interval.

Real-world results of immune checkpoint inhibitors from the Taiwan National Health Insurance Registration System.

OBJECTIVE: Immune checkpoint inhibitors (ICIs) are a major advance in cancer treatment, but their payment benefits are unclear, resulting in financial risk. In Taiwan, the National Health Insurance Administration (NHIA) has adapted risk-sharing mechanisms to cover ICIs by collecting and assessing real-world evidence, such as case registration data, to adjust benefit packages for each medication, increase payment benefits of ICIs, and enable national health insurance sustainability. PATIENTS AND METHODS: This nationwide, multicenter, retrospective cohort study assessed the real-world use, effectiveness, and safety of ICIs reimbursed by the NHIA for treating multiple advanced cancers in Taiwan. We obtained data mainly from the NHIA Immune Checkpoint Inhibitor Registry Database. RESULTS: Between April 1, 2019, and March 31, 2020, 1644 patients received at least one dose of ICIs. The overall response rate (RR) was 29.1%. The metastatic urothelial carcinoma of patients ineligible for chemotherapy showed the highest RR. The estimated median progression-free survival (PFS) was 2.8 months (95% confidence interval [CI]=2.7-3 months), and renal cell carcinoma showed the longest PFS. The median PFS was reached in patients with most cancers except classic Hodgkin's lymphoma, which had a small sample size. The estimated survival probability was 50%. CONCLUSIONS: Under the national registration tracking system, Taiwan's high-cost drug policy has enabled access to new medicines and maximized patient benefits.

Porcine DC-SIGN: molecular cloning, gene structure, tissue distribution and binding characteristics.

DC-SIGN, a human C-type lectin, is involved in the transmission of many enveloped viruses. Here we report the cloning and characterization of the cDNA and gene encoding porcine DC-SIGN (pDC-SIGN). The full-length pDC-SIGN cDNA encodes a type II transmembrane protein of 240 amino acids. Phylogenetic analysis revealed that pDC-SIGN, together with bovine, canis and equine DC-SIGN, are more closely related to mouse SIGNR7 and SIGNR8 than to human DC-SIGN. pDC-SIGN has the same gene structure as bovine, canis DC-SIGN and mouse SIGNR8 with eight exons. pDC-SIGN mRNA expression was detected in pig spleen, thymus, lymph node, lung, bone marrow and muscles. pDC-SIGN protein was found to express on the surface of monocyte-derived macrophages and dendritic cells, alveolar macrophages, lymph node sinusoidal macrophage-like, dendritic-like and endothelial cells but not of monocytes, peripheral blood lymphocytes or lymph node lymphocytes. A BHK cell line stably expressing pDC-SIGN binds to human ICAM-3 and ICAM-2 immunoadhesins in a calcium-dependent manner, and enhances the transmission of porcine reproductive and respiratory syndrome virus (PRRSV) to target cells in trans. The results will help better understand the biological role(s) of DC-SIGN family in innate immunity during the evolutionary process.

Dietary amino acid taurine ameliorates liver injury in chronic hepatitis patients.

The effect of dietary amino acid taurine on the liver function of chronic hepatitis patients was investigated. The 24 chronic hepatitis patients with 2-5 times over normal activities of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) were selected and equally divided into taurine treatment and control groups. In taurine treatment group, each patient took 2 g taurine 3 times a day for three months, and then stopped treatment for 1 month. Patients taking placebo without taurine for 4 months served as a control group. ALT and AST activities and levels of cholesterol, triglyceride and thiobarbituric acid relative substances of serum plasma in the taurine group were all decreased at the end of three month treatment. The study suggested that dietary amino acid taurine may ameliorate liver injury for chronic hepatitis patients.

Nonsteroidal anti-inflammatory drugs increase expression of inducible COX-2 isoform of cyclooxygenase in spinal cord of rats with adjuvant induced inflammation.

Several lines of evidence have accumulated that release of excitatory amino acids, nitric oxide and prostaglandin E2 (PGE2) play a critical role in the development of peripheral tactile and thermal hypersensitivity in chronic inflammatory pain models. Synthesis of PGE2 is controlled by cyclooxygenase (COX), either the COX-1 or COX-2 isoform. COX-2 plays a central role in the inflammatory reactions. The relationship between central sensitization of a complete Freund's adjuvant (CFA) induced inflammation and expressions of COX-2 were assessed in a rat model of CFA injection induced inflammation. Moreover, the time course of analgesia and spinal COX-2 expression following intrathecal (IT) injection with a nonspecific COX inhibitor (ketorolac) and COX-2 inhibitor (celecoxib) were determined using Western blot and immunohistochemistry. COX-2 protein was slightly increased in the lumbosacral spinal cord at 24 h following subcutaneous injection of CFA in the plantar surface of the left hindpaw (p > 0.05). COX-1 was not detected in normal and CFA injection rats. Surprisingly, IT ketorolac or celecoxib significantly increased spinal COX-2 levels at 1 h post-IT injection (p < 0.05) both in inflamed and non-inflamed rats. Then, spinal COX-2 levels declined at 3 and 6 h post-IT injection. These results provide strong in vivo evidence that COX-2 activity but not level may play a central role in the Freund's adjuvant-induced inflammation. However, spinal COX-2 level was upregulated following IT ketorolac and celecoxib injection. These data implies that suppression of PGE2 activity may induce the expression of spinal COX-2 in Freund's adjuvant-induced pain model. Our study concludes that IT administration of COX-2 inhibitor or nonspecific COX inhibitor is associated with significant short-term increase in spinal COX-2 expression.

Dehydroepiandrosterone and dihydrotestosterone recognition by human estrogenic 17beta-hydroxysteroid dehydrogenase. C-18/c-19 steroid discrimination and enzyme-induced strain.

Steroid hormones share a very similar structure, but they behave distinctly. We present structures of human estrogenic 17beta-hydroxysteroid dehydrogenase (17beta-HSD1) complexes with dehydroepiandrosterone (DHEA) and dihydrotestosterone (DHT), providing the first pictures to date of DHEA and DHT bound to a protein. Comparisons of these structures with that of the enzyme complexed with the most potent estrogen, estradiol, revealed the structural basis and general model for sex hormone recognition and discrimination. Although the binding cavity is almost entirely composed of hydrophobic residues that can make only nonspecific interactions, the arrangement of residues is highly complementary to that of the estrogenic substrate. Relatively small changes in the shape of the steroid hormone can significantly affect the binding affinity and specificity. The K(m) of estrone is more than 1000-fold lower than that of DHEA and the K(m) of estradiol is about 10 times lower than that of DHT. The structures suggest that Leu-149 is the primary contributor to the discrimination of C-19 steroids and estrogens by 17beta-HSD1. The critical role of Leu-149 has been well confirmed by site-directed mutagenesis experiments, as the Leu-149 --> Val variant showed a significantly decreased K(m) for C-19 steroids while losing discrimination between estrogens and C-19 steroids. The electron density of DHEA also revealed a distortion of its 17-ketone toward a beta-oriented form, which approaches the transition-state conformation for DHEA reduction.