Volunteering in prisons: a systematic review and narrative synthesis

BACKGROUND

Individuals from the community who volunteer within prisons are an understudied population, despite previous research indicating the increase in involvement of the penal voluntary sector and benefits to both prisons and prisoners from effective implementation of volunteer programmes.

OBJECTIVES

This study aimed to identify the characteristics, motivations and experiences of individuals who volunteer in prisons.

STUDY DESIGN

This was a systematic review conducted according to Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines.

METHODS

Peer-reviewed publications were identified through searchers of five electronic databases (MEDLINE, PsycINFO, Scopus, Applied Social Sciences Index & Abstracts and Social Sciences Database) without date restrictions, supplemented by hand searching and reference checking of retrieved articles. Explicit inclusion and exclusion criteria determined study eligibility. Study quality was appraised using standard tools. A narrative synthesis was conducted, and motivations were organised according to the Volunteer Function Inventory.

RESULTS

Eight studies (five qualitative and three quantitative) reported a total of 764 volunteers across five countries. More than half of the included studies investigated individuals providing primarily religious volunteer support; volunteers in these studies were typically middle aged, White and female. Prison volunteers frequently described motivations related to altruistic or humanitarian values, as well as social reasons. Positive experiences of volunteering were related to personal benefits to volunteers. Negative experiences were related to a lack of support and challenges in volunteers' relationships with prison staff.

CONCLUSIONS

Prison volunteer programmes have the ability to improve the psychological health of prisoners and provide a range of potential benefits to penal systems and volunteers themselves, but research on individuals who volunteer in prisons is limited. Difficulties in the volunteer role could be mitigated by developing formal induction and training packages, promoting closer integration with paid prison staff and providing ongoing supervision. Interventions to improve the volunteer experience should be developed and evaluated.

[Analysis of the clinical characteristics and misdiagnosis of area postrema syndrome manifesting as intractable nausea, vomiting, and hiccups in neuromyelitis optica spectrum disorders]

Objective: To investigate the misdiagnosis of area postrema syndrome (APS) manifesting as intractable nausea, vomiting and hiccups in neuromyelitis optic spectrum disease (NMOSD) and reduce the risk of misdiagnosis. Methods: We retrospectively analyzed data from NMOSD patients attending the Department of Neurology at the First Medical Center of PLA General Hospital between January 2019 and July 2021. SPSS25.0 was then used to analyze the manifestations, misdiagnosis, and mistreatment of APS. Results: A total of 207 patients with NMOSD were included, including 21 males and 186 females. The mean age of onset was 39±15 years (range: 5-72 years). The proportion of patients who were positive for serum aquaporin 4 antibody was 82.6% (171/207). In total, 35.7% (74/207) of the NMOSD patients experienced APS during the disease course; of these patients, 70.3% (52/74) had APS as the first symptom and 29.7% (22/74) had APS as a secondary symptom. The misdiagnosis rates for these conditions were 90.4% (47/52) and 50.0% (11/22), respectively. As the first symptom, 19.2% (10/52) of patients during APS presented only with intractable nausea, vomiting and hiccups; 80.8% (42/52) of patients experienced other neurological symptoms. The Departments of Gastroenterology and General Medicine were the departments that most frequently made the first diagnosis of APS, accounting for 54.1% and 17.6% of patients, respectively. The most common misdiagnoses related to diseases of the digestive system and the median duration of misdiagnosis was 37 days. Conclusions: APS is a common symptom of NMOSD and is associated with a high rate of misdiagnosis. Other concomitant symptoms often occur with APS. Gaining an increased awareness of this disease/syndrome, obtaining a detailed patient history, and performing physical examinations are essential if we are to reduce and avoid misdiagnosis.

[Development and validation of prognostic nomogram for malignant pleural mesothelioma]

Objective: To development the prognostic nomogram for malignant pleural mesothelioma (MPM). Methods: Two hundred and ten patients pathologically confirmed as MPM were enrolled in this retrospective study from 2007 to 2020 in the People's Hospital of Chuxiong Yi Autonomous Prefecture, the First and Third Affiliated Hospital of Kunming Medical University, and divided into training (n=112) and test (n=98) sets according to the admission time. The observation factors included demography, symptoms, history, clinical score and stage, blood cell and biochemistry, tumor markers, pathology and treatment. The Cox proportional risk model was used to analyze the prognostic factors of 112 patients in the training set. According to the results of multivariate Cox regression analysis, the prognostic prediction nomogram was established. C-Index and calibration curve were used to evaluate the model's discrimination and consistency in raining and test sets, respectively. Patients were stratified according to the median risk score of nomogram in the training set. Log rank test was performed to compare the survival differences between the high and low risk groups in the two sets. Results: The median overall survival (OS) of 210 MPM patients was 384 days (IQR=472 days), and the 6-month, 1-year, 2-year, and 3-year survival rates were 75.7%, 52.6%, 19.7%, and 13.0%, respectively. Cox multivariate regression analysis showed that residence (HR=2.127, 95% CI: 1.154-3.920), serum albumin (HR=1.583, 95% CI: 1.017-2.464), clinical stage (stage Ⅳ: HR=3.073, 95% CI: 1.366-6.910) and the chemotherapy (HR=0.476, 95% CI: 0.292-0.777) were independent prognostic factors for MPM patients. The C-index of the nomogram established based on the results of Cox multivariate regression analysis in the training and test sets were 0.662 and 0.613, respectively. Calibration curves for both the training and test sets showed moderate consistency between the predicted and actual survival probabilities of MPM patients at 6 months, 1 year, and 2 years. The low-risk group had better outcomes than the high-risk group in both training (P=0.001) and test (P=0.003) sets. Conclusion: The survival prediction nomogram established based on routine clinical indicators of MPM patients provides a reliable tool for prognostic prediction and risk stratification.

[High-fat intake alleviates lung injury induced by Paragonimus proliferus infection in rats through up-regulating CYP 4A1 expression in lung tissues]

OBJECTIVE

To explore the improvements of high-fat intake on lung injury induced by Paragonimus proliferus infection in rats, and to preliminarily explore the mechanisms underlying the role of cytochrome P450 4A1 (CYP 4A1) in the improve ments.

METHODS

SD rats were randomly assigned into three groups, including the normal control group (n = 10), the infection and normal diet group (n = 12) and the infection and high-fat diet group (n = 12). Rats in the normal control group were fed with normal diet and without any other treatments, and animals in the infection and normal diet group were subcutaneously injected with 8 excysted metacercariae of P. proliferus via the abdominal wall, followed by feeding with normal diet, while rats in the infection and high-fat diet group were subcutaneously injected with 8 excysted metacercariae of P. proliferus via the abdominal wall, followed by feeding with high-fat diet. All rats were sacrificed 28 weeks post-infection, and serum samples and lung specimens were collected. Following hematoxylin-eosin (HE) staining of rat lung specimens, the rat lung injury was observed under an optical microscope, and alveolitis was evaluated using semi-quantitative scoring. Serum interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) levels were measured using enzyme-linked immunosorbent assay (ELISA), and the cytochrome P450 4A1 (CYP 4A1) expression was quantified in rat lung specimens at transcriptional and translational levels using quantitative real-time PCR (qPCR) and Western blotting assays.

RESULTS

Alveolar wall thickening, edema and inflammatory cell infiltration were alleviated 28 weeks post-infection with P. proliferus in rats in the infection and high-fat diet group relative to the infection and normal diet group, and no alveolar consolidation was seen in the infection and high-fat diet group. The semi-quantitative score of alveolitis was significantly higher in the infection and normal diet group [(2.200 ± 0.289) points] than in the normal control group [(0.300 ± 0.083) points] and the infection and high-fat diet group [(1.300 ± 0.475) points] (both P values < 0.05), and higher serum IL-1β [(151.586 ± 20.492)] pg/mL and TNF-α levels [(180.207 ± 23.379) pg/mL] were detected in the infection and normal diet group than in the normal control group [IL-1β: (103.226 ± 3.366) pg/mL; TNF-α: (144.807 ± 1.348) pg/mL] and the infection and high-fat diet group [IL-1β: (110.131 ± 12.946) pg/mL; TNF-α: (131.764 ± 27.831) pg/mL] (all P values < 0.05). In addition, lower CYP 4A1 mRNA (3.00 ± 0.81) and protein expression (0.40 ± 0.02) was quantified in lung specimens in the infection and normal diet group than in the normal control group [(5.03 ± 2.05) and (0.84 ± 0.14)] and the infection and high-fat diet group [(11.19 ± 3.51) and (0.68 ± 0.18)] (all P values < 0.05).

CONCLUSIONS

High-fat intake may alleviate lung injuries caused by P. proliferus infection in rats through up-regulating CYP 4A1 expression in lung tissues at both translational and transcriptional levels.

Construction of PCN-222 and Atomically Thin 2D CNs Van Der Waals Heterojunction for Enhanced Visible Light Photocatalytic Hydrogen Production

Atomically thin two-dimensional (2D) CN sheets have attracted extensive attention in the field of photocatalysis because of their shorter diffusion path of photogenerated carriers and abundant surface reaction sites than bulk CN. However, 2D CNs still exhibit poor visible-light photocatalytic activity because of a strong quantum size effect. Here, PCN-222/CNs vdWHs were successfully constructed using the electrostatic self-assembly method. The results showed that PCN-222/CNs vdWHs with 1 wt.% PCN-222 enhanced the absorption range of CNs from 420 to 438 nm, which improved the absorption capacity of visible light. Additionally, the hydrogen production rate of 1 wt.% PCN-222/CNs is four times that of the pristine 2D CNs. This study provides a simple and effective strategy for 2D CN-based photocatalysts to promote visible light absorption.

NLRP3 Disturbs Treg/Th17 Cell Balance to Aggravate Apical Periodontitis

Apical periodontitis is an inflammatory condition that is considered an immunological reaction of the periapical tissue to invading bacteria and their pathogenic components. Recent research has revealed that NLR family pyrin domain containing 3 (NLRP3) is crucial to the pathogenesis of apical periodontitis and serves as a link between innate and adaptive immunity. The balance between regulatory T-cell (Treg) and T helper cell 17 (Th17 cell) determines the direction of the inflammatory response. Therefore, this study aimed to investigate whether NLRP3 exacerbated periapical inflammation by disturbing Treg/Th17 balance and the underlying regulatory mechanisms. In the present study, NLRP3 was raised in apical periodontitis tissues as opposed to healthy pulp tissues. Low NLRP3 expression in dendritic cells (DCs) increased transforming growth factor β secretion while decreasing interleukin (IL)-1β and IL-6 production. The Treg ratio and IL-10 secretion rose when CD4⁺ T cells were cocultured with DCs primed with IL-1β neutralizing antibody (anti-IL-1β) and specific small interfering RNA (siRNA) targeting NLRP3 (siRNA NLRP3), but the proportion of Th17 cells and IL-17 release dropped. Furthermore, siRNA NLRP3-mediated suppression of NLRP3 expression aided Treg differentiation and elevated Foxp3 expression as well as IL-10 production in CD4⁺ T cells. Inhibition of NLRP3 activity by MCC950 boosted the percentage of Tregs while decreasing the ratio of Th17 cells, leading to reduced periapical inflammation and bone resorption. Nigericin administration, however, exacerbated periapical inflammation and bone destruction with an unbalanced Treg/Th17 response. These findings demonstrate that NLRP3 is a pivotal regulator by regulating the release of inflammatory cytokines from DCs or directly suppressing Foxp3 expression to disturb Treg/Th17 balance, thus exacerbating apical periodontitis.

The relationship of D. pteronyssinus allergic component sIgE and sIgG₄ in house dust mite allergic rhinitis or/and allergic asthma patients

Objective: House-dust mite sensitization is an important cause of allergic asthma and/or rhinitis in southern China. This study aimed to analyze the immune effect and relationship between the Dermatophagoides pteronyssinus components specific immunoglobulin E (sIgE) and sIgG₄. Methods: The serum levels of sIgE and sIgG₄ to D. pteronyssinus allergen components Der p 1, 2, 3, 5, 7, 10, and 23 were detected in 112 patients with allergic rhinitis (AR) and/or allergic asthma (AA). Results: Overall, Der p 1 had the highest positive rate of sIgE (72.3%), followed by Der p 2 (65.2%) and Der p 23 (46.4%). Meanwhile, the highest positive rates of sIgG₄ were for Der p 2 (47.3%), Der p 1 (33.0%), and Der p 23 (25.0%). The patients with AR and AA had a higher positive rate (43.4%) of sIgG₄ than that in the patients with AR (42.4%) and the patients with AA (20.4%; p = 0.043). In patients with AR, the positive rate of sIgE in Der p 1 (84.8%) was higher than that in sIgG₄ (42.4%; p = 0.037), but the positive rate of sIgG₄ in Der p 10 (21.2%) was higher than that in sIgE (18.2%; p < 0.001). Most of the patients were positive for sIgE and sIgG₄ of Der p 2 and Der p 10 at the same time. However, positive results for sIgE alone were just found in Der p 7 and Der p 21. Optimal scale analysis showed that Der p 2, Der p 7, and Der p 21 sIgG₄ were closely related to AR and AA (Cronbach α = 0.917). Conclusion: Herein, the D. pteronyssinus allergen components showed different characteristics among the patients with AR, patients with AA, and patients with AR and AA in southern China. Thus, sIgG₄ may be play an important role in allergic reactions.

Pollen allergens sensitization characteristics and risk factors among allergy rhinitis of children in mainland China: A multicenter study

Background

No comprehensive multicenter study of sensitization patterns among patients with allergic rhinitis (AR) to various common pollen allergens was available nationwide, and risks factors of pollen-induced allergic rhinitis (PiAR) in mainland China was unclear. This study aimed to fill this gap.

Methods

A multicenter study was performed on 736 AR patients aged below 18 from four regions of mainland China. Patients completed a standardized questionnaire asking for the environmental risk factors and AR severity, and undertook skin prick tests (SPT) with 14 common pollen allergens.

Findings

Among the 736 patients, 341 patients (46.33%) suffered at least one positive pollen allergen sensitization. The positive rate of pollen allergens was significantly higher in the high-age group (Damato et al., 2007; Wang et al., 2018; Luo et al., 2016; Demoly et al., 2011; Sampson and Albergo, 1984; Li et al., 2009; Luo et al., 2021; Ziska and Beggs, 2011; Melén et al., 2020; Jensen-Jarolim, 2017; Rönmark et al., 2017; Ge et al., 2017) [6-17] than the low-age group ( ≤ 5), while no significant difference was found between the sexes. The sensitizations to pollen allergens varied widely among four geographical areas. The positive rate was higher in north China and west China than in east China, and south China had the lowest positive rate. The region of residence, ages, ethnic minorities, history of pollen exposure, the material of living room floor and material of pillow were statistically significant risks of PiAR.

Interpretation

This study provides new insights into the pollen allergens sensitization characteristics in AR and the factors affecting PiAR in mainland China.

Characteristics of Allergen Components of Dermatophagoides pteronyssinus in Shrimp and Mite Co-Sensitized Patients in Southern China

INTRODUCTION

Dermatophagoides pteronyssinus (Dp) and shrimp are common air allergens and allergenic food sources, respectively, in southern China. This study aimed to analyze the specific immunoglobulin E (sIgE) characteristics and relationships of Dp components among co-sensitized patients with Dp and shrimp.

MATERIALS AND METHODS

Serum samples were collected from 112 patients with Dp sensitization (61 with shrimp sensitization and 51 without) from southern China. The sIgE concentrations of Dp and shrimp crude extracts were determined by ImmunoCAP, and the sIgE of Dp allergen components (Der p 1, Der p 2, Der p 5, Der p 7, Der p 10, Der p 21, and Der p 23) was detected by protein chip.

RESULTS

Overall, in the Dp-allergic patients, Der p 1 had the highest positive rate (72.3%), followed by Der p 2 (65.2%), Der p 23 (46.4%), Der p 7 (32.14%), Der p 21 (29.46%), Der p 5 (22.32%), and Der p 10 (17.86%). Compared with that in the shrimp nonsensitized group, the positive rate of sIgE for Der p 10 (27.87% vs. 5.88%, p = 0.002) in the shrimp sensitization group was significantly higher; however, the positive rate of sIgE for Der p 7 (22.95% vs. 43.14%, p = 0.023) was significantly lower. Moreover, the concentration of sIgE for Der p 10 increased statistically in the shrimp-sensitized group. The correlation analysis also showed that shrimp sensitization was significantly correlated with Der p 10.

CONCLUSION

Among patients with Dp sensitization, Der p 1 had the highest positive rate, followed by Der p 2 and Der p 23. Meanwhile, Der p 10 may play an important role in patients with shrimp sensitization, while Der p 7 may be the meaningful allergen component in patients with Dp sensitization alone. In general, component-resolved diagnosis technology in clinical practice can effectively guide patients with polysensitization to avoid allergic substances.

Anticeramide Improves Sjögren's Syndrome by Blocking BMP6-Induced Th1

T-cell dysfunction has been shown to play an important role in the pathogenesis of Sjögren's syndrome (SS). In recent studies, the increased expression of BMP6 has been reported to be related to SS. However, the roles that BMP6 plays in immune homeostasis in the development of SS as well as the downstream signals activated by BMP6 remain unclear. In this study, we investigated the effects and molecular mechanisms of BMP6 on naive CD4⁺ T cells, showing that BMP6 could upregulate interferon (IFN)-γ secretion from CD4⁺ T cells through a ceramide/nuclear factor-κB pathway, with no effect on T-cell activation or proliferation. Moreover, an in vivo study showed that anticeramide treatment (myriocin) for an SS animal model (NOD/LtJ mice) could significantly decrease the IFN-γ expression and Th1 frequency in the salivary glands and suppress the inflammation infiltration in salivary glands and maintain the salivary flow rates, both of which reflect SS-like symptoms. This study identifies a promising target that could effectively attenuate the abnormal state of CD4⁺ T cells and reverse the progression of SS.

Association between Dried Fruit Intake and DNA Methylation: A Multivariable Mendelian Randomization Analysis

OBJECTIVES

Observational studies have reported associations between dried fruit intake and DNA methylation(DNAm). However, inherent flaws in observational study designs make them susceptible to confounding and reverse causality bias. Consequently, it is unclear whether a causal association exists. In the present study, we aimed to investigate the causal associations between dried fruit intake and DNAm.

METHODS

We performed two-sample Mendelian randomization (MR) using the IEU Open GWAS database aggregated data. Forty-three single nucleotide polymorphisms (SNPs) associated with dried fruit intake as instrumental variables (IVs) were selected as exposure. DNAm outcomes include Gran (estimated granulocyte proportions); AgeAccelGrim(GrimAge acceleration); Hannum (Hannum age acceleration); IEAA(Intrinsic epigenetic age acceleration), AgeAccelPheno( PhenoAge acceleration), and DNAmPAIadjAge (DNAm-estimated plasminogen activator inhibitor-1 levels). We used the MR pleiotropy residual sum and outlier test (MRPRESSO) and Radial-MR test to identify any level of multi-effect outliers and assessed the causal effect estimates(after removing outliers). The primary causal effects were estimated using inverse-variance weighted (IVW) method and undertook sensitivity analyses using MR methods robust to horizontal pleiotropy.The direct effects of dried fruit intake on DNAm were estimated using multivariable mendelian randomization (MVMR).

RESULTS

Leveraging two-sample MR analysis, we observed statistically significant associations between dried fruit intake with a lower AgeAccelGrim(β=-1.365, 95% confidence intervals [CI] -2.266 to -0.464, PIVW=2.985×10-3) and AgeAccelPheno (β= -1.933, 95% CI -3.068 to -0.798, PIVW=8.371×10-4). By contrast, the effects level on Gran (β=0.008, PIVW=0.430), Hannum(β=-0.430, PIVW=0.357), IEAA(β=-0.184, PIVW=0.700), and DNAmPAIadjAge (β=-1.861, PIVW=0.093) were not statistically significant. MVMR results adjusting for the potential effects of confounders showed that the causal relationship between dried fruit intake and AgeAccelGrim(β= -1.315, 95% CI -2.373 to -0.258, PIVW=1.480×10-2) and AgeAccelPheno(β= -1.595, 95% CI -2.987 to -0.202, PIVW=2.483×10-2) persisted. No significant horizontal polymorphism was found in the sensitivity analysis.

CONCLUSION

Our MR study suggested that increased dried fruit intake is associated with slower AgeAccelGrim and AgeAccelPheno. It can providing a promising avenue for exploring the beneficial effects of dried fruit intake on lifespan extension.

Diagnostic Strategy and Prognostic Factors for Ectopic Adrenocorticotropic Hormone Syndrome: A Retrospective Study of 64 Cases

INTRODUCTION

Ectopic adrenocorticotropic hormone (ACTH) syndrome (EAS) is a serious life-threatening disease. Tumor localization is crucial in EAS management. This underscores the importance of evaluating imaging methods and prognostic factors to provide a clear basis for patient diagnosis and management.

OBJECTIVE

The aim of this study was to investigate imaging methods and analyze the relevant prognostic factors for EAS.

METHODS

The retrospective study followed 64 cases of EAS diagnosed between 1992 and 2020. Clinical features, biochemical analysis, and imaging studies were collected, and survival data were followed up and analyzed.

RESULTS

Of 64 patients, 41% were female with a mean (±SD) age at diagnosis of 47 ± 16 years. Computed tomography (CT), 18-F fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)-CT, and octreotide scintigraphy had similar sensitivity in localizing ectopic ACTH-secreting tumors. However, in cases with negative imaging on CT, both of 18F-FDG PET-CT and octreotide scintigraphy further localized 25% tumors. The combination of all three modalities failed to further increase the sensitivity. Patients with thymic tumors survived longer than those with pulmonary or pancreatic tumors (p = 0.013 and 0.047, respectively). Multivariate analyses showed that hypokalemia (p = 0.004) and treatment modality (p = 0.048) were independent prognostic factors. The optimal serum potassium cutoff based on maximum log-rank statistics (p = 0.012) was 2.90 mmol/L.

CONCLUSION

CT is the first choice for tumor localization in EAS. CT in combination with a nuclear medicine or molecular imaging modality is necessary for further identification of an ectopic source. Serum potassium <2.90 mmol/L is associated with shorter overall survival, and tumor resection plays the most important role in the survival improvement.

[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 I_KATP 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.