Tumor immunotherapy resistance: Revealing the mechanism of PD-1 / PD-L1-mediated tumor immune escape.

Tumor immunotherapy, an innovative anti-cancer therapy, has showcased encouraging outcomes across diverse tumor types. Among these, the PD-1/PD-L1 signaling pathway is a well-known immunological checkpoint, which is significant in the regulation of immune evasion by tumors. Nevertheless, a considerable number of patients develop resistance to anti-PD-1/PD-L1 immunotherapy, rendering it ineffective in the long run. This research focuses on exploring the factors of PD-1/PD-L1-mediated resistance in tumor immunotherapy. Initially, the PD-1/PD-L1 pathway is characterized by its role in facilitating tumor immune evasion, emphasizing its role in autoimmune homeostasis. Next, the primary mechanisms of resistance to PD-1/PD-L1-based immunotherapy are analyzed, including tumor antigen deletion, T cell dysfunction, increased immunosuppressive cells, and alterations in the expression of PD-L1 within tumor cells. The possible ramifications of altered metabolism, microbiota, and DNA methylation on resistance is also described. Finally, possible resolution strategies for dealing with anti-PD-1/PD-L1 immunotherapy resistance are discussed, placing particular emphasis on personalized therapeutic approaches and the exploration of more potent immunotherapy regimens.

Exploring the pharmacological mechanism of Wuzhuyu decoction on hepatocellular carcinoma using network pharmacology.

BACKGROUND: Wuzhuyu decoction, a traditional Chinese medicinal formula, is effective in treating hepatocellular carcinoma (HCC). AIM: To explore the potential mechanism of action of Wuzhuyu decoction against HCC. METHODS: The active components of each Chinese herbal medicinal ingredient in Wuzhuyu decoction and their targets were obtained from the Traditional Chinese Medicine Database and Analysis Platform. HCC was used as a search query in GeneCards, Online Mendelian Inheritance in Man, Malacards, DisGeNET, Therapeutic Target Database, and Comparative Toxicogenomics Database. The overlapping targets of the Wuzhuyu decoction and HCC were defined, and then protein-protein interaction, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed. CytoHubba was used to select hub genes, and their binding activities and key active components were verified using molecular docking. RESULTS: A total of 764 compounds, 77 active compounds, and 204 potential target genes were identified in Wuzhuyu decoction. For HCC, 9468 potential therapeutic target genes were identified by combining the results from the six databases and removing duplicates. A total of 179 overlapping targets of Wuzhuyu decoction and HCC were defined, including 10 hub genes (tumor necrosis factor, interleukin-6, AKT1, TP53, caspase-3, mitogen-activated protein kinase 1, epidermal growth factor receptor, MYC, mitogen-activated protein kinase 8, and JUN). There were six main active components (quercetin, kaempferol, ginsenoside Rh2, rutaecarpine, ß-carotene, and ß-sitosterol) that may act on hub genes to treat HCC in Wuzhuyu decoction. Kyoto Encyclopedia of Genes and Genomes enrichment analysis mainly involved the mitogen-activated protein kinase, p53, phosphatidylinositol-4,5-bisphosphate 3-kinase-Akt, Janus kinase-signal transducer of activators of transcription, and Hippo signaling pathways. Further verification based on molecular docking results showed that the small molecule compounds (quercetin, kaempferol, ginsenoside Rh2, rutaecarpine, ß-carotene, and ß-sitosterol) contained in Wuzhuyu decoction generally have excellent binding affinity to the macromolecular target proteins encoded by the top 10 genes. CONCLUSION: This study revealed that Wuzhuyu decoction may be a latent multicomponent, multitarget, and multipathway treatment for HCC. It provided novel insights for verifying the mechanism of Wuzhuyu decoction in the treatment of HCC.

Variational perturbation theory for dynamic polarizabilities and dispersion coefficients.

An efficient method based on the variational perturbation theory (VPT) is proposed to conveniently calculate the atomic real- and imaginary-frequency dynamic polarizabilities and the interatomic dispersion coefficients. The developed method holds the great advantage that only the system ground state wave function and corresponding radial mean values are needed. Verification of the VPT method on one- and two-electron atoms indicates that the present approximation shows good agreement with calculations based on the sophisticated sum-over-states method. We apply the VPT method to examine the approximate Z-scaling laws of polarizabilities and dispersion coefficients in the He isoelectronic sequence, and to investigate the plasma screening effect on these quantities for embedded atoms. Our calculation demonstrates very well that the VPT method is capable of producing reasonably accurate static and dynamic polarizabilities as well as two- and three-atom dispersion coefficients for plasma-embedded atoms in a wide range of screening parameters.

Hyperpolarizabilities of hydrogenlike atoms in Debye and dense quantum plasmas.

The hyperpolarizabilities of the hydrogenlike atoms in Debye and dense quantum plasmas are calculated using the sum-over-states formalism based on the generalized pseudospectral method. The Debye-Hückel and exponential-cosine screened Coulomb potentials are employed to model the screening effects in, respectively, Debye and dense quantum plasmas. Our numerical calculation demonstrates that the present method shows exponential convergence in calculating the hyperpolarizabilities of one-electron systems and the obtained results significantly improve previous predictions in the strong screening environment. The asymptotic behavior of hyperpolarizability near the system bound-continuum limit is investigated and the results for some low-lying excited states are reported. By comparing the fourth-order corrected energies in terms of hyperpolarizability with the resonance energies using the complex-scaling method, we empirically conclude that the applicability of hyperpolarizability in perturbatively estimating the system energy in Debye plasmas lies in the range of [0,F_{max}/2], where F_{max} refers to the maximum electric field strength at which the fourth-order energy correction is equal to the second-order term.

Recent advances in optical aptasensors for biomarkers in early diagnosis and prognosis monitoring of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) accounts for approximately 90% of all primary liver cancers and is one of the main malignant tumor types globally. It is essential to develop rapid, ultrasensitive, and accurate strategies for the diagnosis and surveillance of HCC. In recent years, aptasensors have attracted particular attention owing to their high sensitivity, excellent selectivity, and low production costs. Optical analysis, as a potential analytical tool, offers the advantages of a wide range of targets, rapid response, and simple instrumentation. In this review, recent progress in several types of optical aptasensors for biomarkers in early diagnosis and prognosis monitoring of HCC is summarized. Furthermore, we evaluate the strengths and limitations of these sensors and discuss the challenges and future perspectives for their use in HCC diagnosis and surveillance.

Contribution of calcium dysregulation to impaired coronary artery contraction in Zucker diabetic fatty rats.

Diabetic coronary artery injury is closely associated with Ca2+ dysregulation, although the underlying mechanism remains unclear. This study explored the role and mechanism of Ca2+ handling in coronary artery dysfunction in type 2 diabetic rats. Zucker diabetic fatty (ZDF) rats were used as the type 2 diabetes mellitus model. The contractility of coronary artery rings induced by KCl, CaCl2 , 5-HT and U46619 was significantly lower in ZDF rats than in Zucker lean rats. Vasoconstriction induced by 5-HT and U46619 was greatly inhibited by nifedipine. However, in the presence of 1 µM nifedipine or in the Ca2+ -free KH solution containing 1 µM nifedipine, there was no difference in the vasoconstriction between Zucker lean and ZDF rats. Store-operated calcium channels (SOCs) were not involved in coronary vasoconstriction. The downregulation of contractile proteins and the upregulation of synthesized proteins were in coronary artery smooth muscle cells (CASMCs) from ZDF rats. Metformin reversed the reduction of vasoconstriction in ZDF rats. Taken together, L-type calcium channel is important for regulating the excitation-contraction coupling of VSMCs in coronary arteries, and dysregulation of this channel contributes to the decreased contractility of coronary arteries in T2DM.

PD-L1 blockade liberates intrinsic antitumourigenic properties of glycolytic macrophages in hepatocellular carcinoma.

OBJECTIVE: Patients with increased PD-L1+ host cells in tumours are more potent to benefit from antiprogrammed death-1/programmed death ligand-1 (PD-L1) treatment, but the underlying mechanism is still unclear. We aim to elucidate the nature, regulation and functional relevance of PD-L1+ host cells in hepatocellular carcinoma (HCC). DESIGN: A total of untreated 184 HCC patients was enrolled randomly. C57BL/6 mice are given injection of Hepa1-6 cells to form autologous hepatoma. ELISpot, flow cytometry and real-time PCR are applied to analyse the phenotypic characteristics of PD-L1+ cells isolated directly from HCC specimens paired with blood samples or generated from ex vivo and in vitro culture systems. Immunofluorescence and immunohistochemistry are performed to detect the presence of immune cells on paraffin-embedded and formalin-fixed samples. The underlying regulatory mechanisms of metabolic switching are assessed by both in vitro and in vivo studies. RESULTS: We demonstrate that PD-L1+ host macrophages, which constructively represent the major cellular source of PD-L1 in HCC tumours, display an HLA-DRhighCD86high glycolytic phenotype, significantly produce antitumourigenic IL-12p70 and are polarised by intrinsic glycolytic metabolism. Mechanistically, a key glycolytic enzyme PKM2 triggered by hepatoma cell derived fibronectin 1, via a HIF-1α-dependent manner, concurrently controls the antitumourigenic properties and inflammation-mediated PD-L1 expression in glycolytic macrophages. Importantly, although increased PKM2+ glycolytic macrophages predict poor prognosis of patients, blocking PD-L1 on these cells eliminates PD-L1-dominant immunosuppression and liberates intrinsic antitumourigenic properties. CONCLUSIONS: Selectively modulating the 'context' of glycolytic macrophages in HCC tumours might restore their antitumourigenic properties and provide a precise strategy for anticancer therapy.

Single-Cell RNA Sequencing Analysis of the Heterogeneity in Gene Regulatory Networks in Colorectal Cancer.

Colorectal cancer (CRC) manifests as gastrointestinal tumors with high intratumoral heterogeneity. Recent studies have demonstrated that CRC may consist of tumor cells with different consensus molecular subtypes (CMS). The advancements in single-cell RNA sequencing have facilitated the development of gene regulatory networks to decode key regulators for specific cell types. Herein, we comprehensively analyzed the CMS of CRC patients by using single-cell RNA-sequencing data. CMS for all malignant cells were assigned using CMScaller. Gene set variation analysis showed pathway activity differences consistent with those reported in previous studies. Cell-cell communication analysis confirmed that CMS1 was more closely related to immune cells, and that monocytes and macrophages play dominant roles in the CRC tumor microenvironment. On the basis of the constructed gene regulation networks (GRNs) for each subtype, we identified that the critical transcription factor ERG is universally activated and upregulated in all CMS in comparison with normal cells, and that it performed diverse roles by regulating the expression of different downstream genes. In summary, molecular subtyping of single-cell RNA-sequencing data for colorectal cancer could elucidate the heterogeneity in gene regulatory networks and identify critical regulators of CRC.

Tribbles pseudokinase 3 (TRIB3) contributes to the progression of hepatocellular carcinoma by activating the mitogen-activated protein kinase pathway.

BACKGROUND: Tribble pseudokinase 3 (TRIB3) plays a key role in regulating the malignancy of many tumors. This study examined its function in cancer cells and explored the potential mechanisms of action. METHODS: The expression of TRIB3 was examined in hepatocellular carcinomas (HCCs) using The Cancer Genome Atlas (TCGA) database. A TRIB3 lentivirus with a flag label was constructed and transfected into Huh7 and Hep3B human hepatoma cell lines to generate cells that stably overexpress TRIB3. A small interfering RNA (siRNA) was designed to knockdown TRIB3 mRNA in HepG2 and Huh7. Cell viability and cell colony formation assays were conducted. Flow cytometry was performed to assess the cell cycle in cells overexpressing TRIB3. Western blotting were performed to examine the expression of (Mitogen-activated protein kinase, MAPKK) (MEK), phosphorylated-MEK (p-MEK), extracellular signal-regulated kinase (ERK), and p-MEK in cells with TRIB3 knockdown. The correlation between TRIB3 and SMARCD3 was assessed using co-immunoprecipitation assays and immunofluorescence. RESULTS: TRIB3 was significantly overexpressed in advanced grade HCC tissues and was closely correlated with poor prognosis. TRIB3 overexpression promoted the cell growth and cell cycle but had little effect on migration capabilities in Huh7 and Hep3B cells. Conversely, knockdown of TRIB3 had slow down the cell growth in Huh7 and HepG2 cells detected by CCK8 and colony formation assay. The expression of MEK and ERK at both the protein and mRNA levels were downregulated when TRIB3 was knocked down. The protein expression of p-ERK and p-MEK were also downregulated upon TRIB3 silencing. SMARCD3 is a transcript factor that is belongs to the SWI/SNF complex and has been shown to regulate many genes. Indeed, co-immunoprecipitation assays demonstrated that TRIB3 interacts with SMARCD3 in the nucleus, suggesting that it may regulate TRIB3 in HCCs. CONCLUSIONS: This study demonstrated that TRIB3 promotes the malignancy of HCC cells and its expression may be a potential diagnostic biomarker for HCC progression.

Impact of Plasma Exposure of Statins and Their Metabolites With Major Adverse Cardiovascular Events in Chinese Patients With Coronary Artery Disease.

The selection of optimum statin intensity is inconclusive, and the association of plasma exposure of statins and metabolites with major adverse cardiovascular events (MACEs) is unclear. This study sought to compare the effect of low (quartile 1), intermediate (quartiles 2 and 3), and high (quartile 4) plasma exposure of statins and metabolites on MACE, re-ischemia events and death in patients with coronary artery disease (CAD) at 5 years. A total of 1,644 patients in atorvastatin (AT) cohort and 804 patients in rosuvastatin (RST) cohort were included, and their plasma concentration of statins and metabolites was categorized as low-, mid-, or high-group. The association between the plasma levels of statins and metabolites and the incidence of primary endpoint in patients was assessed by Cox proportional hazard models. Intensive AT exposure (Q4 > 5.32 ng/ml) was significantly associated with increased risk of death compared with low (hazard ratio [HR]: 1.522; 95% confidence interval [CI]: 1.035-1.061; P = 0.0022) or moderate exposure (HR: 2.054; 95% CI: 1.348-3.130; P = 0.0008). This association was also found in AT's five metabolites (all P < 0.01). In patients with RST treatment, moderate RST concentration (0.53-4.29 ng/ml) versus low concentration had a significantly lower risk of MACE and re-ischemia events. (HR: 0.532, 95% CI: 0.347-0.815, P = 0.0061 and HR: 0.505, 95% CI: 0.310-0.823, P = 0.0061, respectively). A higher plasma exposure of AT and metabolites has a significantly higher risk of death, and moderate RST exposure has a significantly lower risk of MACE and re-ischemia events in Chinese patients with CAD. The harms of high plasma exposure should be considered when prescribing statins to patients because it may be a risk factor for having poor prognosis in patients with CAD.

Comparison of Ca2+ Handling for the Regulation of Vasoconstriction between Rat Coronary and Renal Arteries.

BACKGROUND: Ca2+ plays an important role in the regulation of vasoconstriction. Ca2+ signaling is regulated by a number of Ca2+-handling proteins. However, whether differences in Ca2+ handling affect the regulation of vasoconstriction in different arteries remains elusive. OBJECTIVE: To determine whether differences in Ca2+ handling affect the response to vasoconstrictors in different arteries. METHODS: Arterial ring contraction was measured using a Multi Myograph System. Vascular smooth muscle cells (VSMCs) were digested with type 2 collagenase in DMEM, then intracellular calcium concentration was measured with the Ca2+ probe fluo-4/AM in the isolated cells. Calcium-related proteins were assayed by Western blotting. RESULTS: Phenylephrine did not induce -coronary arterial contraction. There were differences in -5-hydroxytryptamine, 9,11-dideoxy-11a,9a-epoxymethano-prostaglandin F2a, and endothelin 1-induced vasoconstriction in different solutions between coronary and renal arteries. Vasoconstrictions in the presence of Bay K8644 were stronger in coronary than in renal arteries. Store-operated calcium (SOC) channels could mediate Ca2+ influx in VSMCs of both groups. SOC channels did not participate in the contraction of coronary arteries. In addition, there were significant differences in the expressions of receptors and ion channels between the two groups. CONCLUSIONS: Ca2+ handling contributed to the different responses to vasoconstrictors between coronary and renal arteries.

A novel PNPLA6 compound heterozygous mutation identified in a Chinese patient with Boucher­Neuhäuser syndrome.

The combination of cerebellar degeneration, hypogonadotropic hypogonadism and chorioretinal dystrophy defines Boucher­Neuhäuser syndrome (BNS), which has been associated with autosomal­recessive mutations in the patatin­like phospholipase domain containing 6 (PNPLA6) gene. However, no BNS cases have been reported in mainland China. In the present study, to the best of the authors' knowledge, the first patient with BNS was identified in China. A 39­year­old male was first diagnosed with hypogonadotropic hypogonadism. The proband additionally exhibited retinal degeneration and cerebellar dystrophy. Whole exome sequencing identified a compound heterozygous mutation in PNPLA6 (c.3386G>T+ c.3534G>C). The mutant amino acids were highly conserved and the mutations were predicted to be deleterious. This result further confirmed the role of PNPLA6 in BNS and suggested that whole exome sequencing may be applied for the diagnosis of complex syndromes, including BNS, prior to the observation of obvious symptoms.

miR­21 attenuates contrast­induced renal cell apoptosis by targeting PDCD4.

Contrast medium (CM) is widely used in cardiac catheterization; however, it may induce acute kidney injury or renal failure, although the underlying mechanism remains to be elucidated. MicroRNA­21 (miR­21) is involved in renal disease and has been indicated to regulate cellular apoptosis and fibrosis, although its role in CM­induced renal cell injury is unknown. The present study examined the expression and potential targets of miR­21 in human renal proximal tubular epithelial (HK­2) cells following CM treatment. CM induced renal cell apoptosis and decreased miR­21 expression. The expression level of the apoptosis regulator protein, B­cell lymphoma 2 (Bcl­2) was upregulated, whereas that of the apoptosis regulator, Bcl­2­associated X protein (Bax) was downregulated upon transfection of miR­21 mimics; miR­21 overexpression additionally directly inhibited the expression of programmed cell death protein 4 (PDCD4), as determined by a dual luciferase reporter assay, and PDCD4 silencing reduced the rate of HK­2 cell apoptosis. The results of the present study indicated that miR­21 protected renal cells against CM­induced apoptosis by regulating PDCD4 expression.

Determination of a novel B-Raf(V600E) and EGFR dual inhibitor in rat plasma by HPLC-MS/MS and its application in a pharmacokinetic study.

The EGFR and B-Raf(V600E) dual inhibition is a promising strategy in treatment of colorectal cancer patients with B-Raf(V600E) mutation. Previously, compound 3 was designed and synthesized as a novel B-Raf(V600E) and EGFR dual inhibitor with highly potency in both kinase and cell based assay. Herein, a sensitive and rapid HPLC-MS/MS quantitative method was developed and validated for the further pharmacokinetic evaluation of compound 3 in rats.

Species-specific differences in the role of L-type Ca²âº channels in the regulation of coronary arterial smooth muscle contraction.

The L-type calcium channel (LCC) plays a regulatory role in various physical and pathological processes. In the vasculature, LCCs mediate agonist-induced vascular smooth muscle contraction. However, whether LCC-mediated vessel responses to certain vasoconstrictors vary among species remains unclear. The coronary arteries were dissected from the hearts of rats and mice. Coronary arterial ring contraction was measured using the Multi Myograph system. High K+ (60 mM)-induced coronary artery contractions were stronger in rats than in mice, whereas CaCl2-induced contraction curves did not differ significantly between the two groups. Endothelin-1, U46619 (thromboxane A2 receptor agonist), and 5-hydroxytryptamine (5-HT) induced concentration-dependent vasoconstriction of coronary arterial rings in rats and mice. The vessel rings of mice were more sensitive to ET-1 and U46619 and less sensitive to 5-HT than those of rats. The LCC blocker nifedipine significantly inhibited coronary artery contractions induced by ET-1, U46619, and 5-HT. The inhibitory effect of 1 µM nifedipine on ET-1- and 5-HT-induced coronary artery contractions was stronger in mice than in rats, whereas its effect on U46619-induced vessel contractions was weaker in mice than in rats. The 5-HT2A receptor and LCC mRNA levels were higher in the coronary arteries of rats than in those of mice, whereas the expressions of the ETA and TXA2 receptors and Orai1 mRNA levels were comparable between the two groups. LCC plays an important role in coronary arterial contraction. Rats and mice show different responses to vasoconstrictors and LCC blockers, suggesting that the coronary arteries of rats and mice have different biological characteristics.

Population pharmacokinetics and safety of eptifibatide in healthy Chinese volunteers and simulations on the dose regimens approved for a Western population.

OBJECTIVE: This study was designed to evaluate the pharmacokinetics (PK) and safety of eptifibatide in healthy Chinese volunteers and provide information for the further study in the Chinese population. METHODS: 30 healthy volunteers (15 male) were enrolled in the study and divided into three dose groups (45 µg x kg⁻¹, 90 µg x kg⁻¹, and 180 µg x kg⁻¹). Plasma and urine samples were drawn after one single-bolus administration and measured by LC-MS/MS. The plasma and urine data were analyzed simultaneously by the population approach using the NONMEM software and evaluated by the visual predicted check (VPC) and bootstraping. The PK profiles of dose regimens approved for a Western population in the Chinese population were simulated. RESULTS: A two-compartment model adequately described the PK profiles of eptifibatide. The clearance (CL) and the distribution volume (V1) of the central compartment were 0.128 L x h⁻¹ x kg⁻¹ and 0.175 L x kg⁻¹, respectively. The clearance (Q) and V2of the peripheral compartment were 0.0988 L x h⁻¹ x kg⁻¹ and 0.147 L x kg⁻¹, respectively. The elimination fraction from plasma to urine (F0) was 17.2%. No covariates were found to have a significant effect. Inter-individual variabilites were all within 33.9%. The VPC plots and bootstrap results indicated good precision and prediction of the model. The simulations of the approved regimens in the Chinese population showed much lower steady-state concentrations than the target concentration obtained from the Western clinical trials. No severe safety events were found in this study. CONCLUSIONS: The PK model of eptifibatide was established and could provide PK information for further studies in the Chinese population.

Upregulation of 5-hydroxytryptamine receptor signaling in coronary arteries after organ culture.

BACKGROUND: 5-Hydroxytryptamine (5-HT) is a powerful constrictor of coronary arteries and is considered to be involved in the pathophysiological mechanisms of coronary-artery spasm. However, the mechanism of enhancement of coronary-artery constriction to 5-HT during the development of coronary artery disease remains to be elucidated. Organ culture of intact blood-vessel segments has been suggested as a model for the phenotypic changes of smooth muscle cells in cardiovascular disease. METHODOLOGY/PRINCIPAL FINDINGS: We wished to characterize 5-HT receptor-induced vasoconstriction and quantify expression of 5-HT receptor signaling in cultured rat coronary arteries. Cumulative application of 5-HT produced a concentration-dependent vasoconstriction in fresh and 24 h-cultured rat coronary arteries without endothelia. 5-HT induced greater constriction in cultured coronary arteries than in fresh coronary arteries. U46619- and CaCl2-induced constriction in the two groups was comparable. 5-HT stimulates the 5-HT2A receptor and cascade of phospholipase C to induce coronary vasoconstriction. Calcium influx through L-type calcium channels and non-L-type calcium channels contributed to the coronary-artery constrictions induced by 5-HT. The contractions mediated by non-L-type calcium channels were significantly enhanced in cultured coronary arteries compared with fresh coronary arteries. The vasoconstriction induced by thapsigargin was also augmented in cultured coronary arteries. The decrease in Orai1 expression significantly inhibited 5-HT-evoked entry of Ca2+ in coronary artery cells. Expression of the 5-HT2A receptor, Orai1 and STIM1 were augmented in cultured coronary arteries compared with fresh coronary arteries. CONCLUSIONS: An increased contraction in response to 5-HT was mediated by the upregulation of 5-HT2A receptors and downstream signaling in cultured coronary arteries.

Effect of ranolazine on rat intrarenal arteries in vitro.

Ranolazine is mainly used to treat patients with chronic stable angina in clinical practice. However, ranolazine does not lower significantly systemic blood pressure. The direct effect of ranolazine on vascular tone remains unknown. In the present study, we investigated the vascular effects and mechanisms of action of ranolazine in isolated rat intrarenal arteries. Rings of intrarenal arteries were mounted in a small vessel myography using two stainless steel wires for the measurement of isometric tension. L-type Ca²âº currents were recorded in isolated single renal arterial smooth muscle cells using patch clamp techniques in whole-cell mode. Ranolazine induced concentration-dependent relaxations in rings contracted with phenylephrine, but ranolazine failed to cause any relaxation in rings pre-contracted by U46619, 5-HT or endothelin-1. Ranolazine also induced relaxations in norepinephrine pre-contracted rings. Yohimbine failed to induce relaxation in rings pre-contracted by norepinephrine. Propranolol did not affect ranolazine-induced relaxation but the relaxant effect of ranolazine was much less than that of prazosin. Ranolazine-induced relaxations were slight but significantly attenuated by endothelial denudation. Partial inhibition was observed in endothelium-intact arteries exposed to a combination of iberiotoxin and apamin. Ranolazine at higher concentration (>30 µM) inhibited Ca²âº-induced contraction in a noncompetitive manner. Ranolazine reduced L-type Ca²âº currents at potentials between -30 and 50 mV in isolated renal artery myocytes. Therefore it can be said that ranolazine has significant α1-adrenergic receptor and weak calcium channel antagonistic effects in rat intrarenal arteries.

Association between polymorphisms of the renin-angiotensin system and coronary artery disease in Chinese patients with type 2 diabetes.

BACKGROUND: The renin-angiotensin system (RAS) is regarded as one of the most important regulatory systems for cardiovascular homeostasis. In this study, we investigated associations of the five genetic polymorphisms in the RAS and presence of coronary artery disease (CAD) in type 2 diabetes. METHODS: Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism analysis. We used the generalised multifactor dimensionality reduction (GMDR) method to identify gene-gene interactions. RESULTS: The D allele in the ACE gene was significantly more frequent in type 2 diabetic patients with CAD (p = 0.04). In multivariate logistic regression analysis, the DD genotype was associated with a significantly increased risk of CAD (p = 0.044). 1675G/A variant in the AT2R gene was found to be associated with CAD in female subjects with type 2 diabetes (p = 0.025). The three other polymorphisms of the RAS do not seem to influence the development of CAD in type 2 diabetes. No significant gene-gene interaction for any combinations of genotypes was found in the GMDR method. CONCLUSION: The DD variant of the ACE gene polymorphism is associated with increased risk of developing CAD in Chinese patients with type 2 diabetes. A slight impact of AT2R 1675G/A polymorphism on CAD was found only in female diabetic patients.

Allitridi inhibits transient outward potassium currents in human atrial myocytes.

1. It has been reported that allitridi, an active compound extracted from garlic, has many cardiovascular effects. However, it remains unknown whether allitridi affects major repolarization currents, such as the transient outward K(+) current (I(to) ), ultrarapid delayed rectifier K(+) current (I(Kur)) and the L-type Ca(2+) current (I(Ca)), in human atrial myocytes. 2. In the present study, we investigated the effects of allitridi on I(to), I(Kur), I(Ca) and the action potential in human isolated atrial myocytes using the whole-cell patch recording technique. 3. Allitridi reversibly inhibited I(to), but not I(Kur) and I(Ca), in human atrial myocytes. These effects of allitridi on I(to) were concentration dependent (IC(50) = 44.9 µmol/L). Inactivation of I(to) was accelerated and the voltage-dependent inactivation potential was shifted towards the negative direction. Allitridi (30 µmol/L) significantly prolonged action potential duration in human atrial myocytes. 4. The results of the present study indicate that allitridi inhibits I(to), but not I(Kur) and I(Ca), and prolongs the action potential duration in human atrial myocytes.