Phospholamban regulates nuclear Ca2+ stores and inositol 1,4,5-trisphosphate mediated nuclear Ca2+ cycling in cardiomyocytes

AIMS

Phospholamban (PLB) is the key regulator of the cardiac Ca²⁺ pump (SERCA2a)-mediated sarcoplasmic reticulum Ca²⁺ stores. We recently reported that PLB is highly concentrated in the nuclear envelope (NE) from where it can modulate perinuclear Ca²⁺ handling of the cardiomyocytes (CMs). Since inositol 1,4,5-trisphosphate (IP₃) receptor (IP₃R) mediates nuclear Ca²⁺ release, we examined whether the nuclear pool of PLB regulates IP₃-induced nuclear Ca²⁺ handling.

METHODS AND RESULTS

Fluo-4 based confocal Ca²⁺ imaging was performed to measure Ca²⁺ dynamics across both nucleus and cytosol in saponin-permeabilized CMs isolated from wild-type (WT) or PLB-knockout (PLB-KO) mice. At diastolic intracellular Ca²⁺ ([Ca²⁺]_i = 100 nM), the Fab fragment of the monoclonal PLB antibody (anti-PLB Fab) facilitated the formation and increased the length of spontaneous Ca²⁺ waves (SCWs) originating from the nuclear region in CMs from WT but not from PLB-KO mice. We next examined nuclear Ca²⁺ activities at basal condition and after sequential addition of IP₃, anti-PLB Fab, and the IP₃R inhibitor 2-aminoethoxydiphenyl borate (2-APB) at a series of [Ca²⁺]_i. In WT mice, at 10 nM [Ca²⁺]_i where ryanodine receptor (RyR2) based spontaneous Ca²⁺ sparks rarely occurred, IP₃ increased fluorescence amplitude (F/F₀) of overall nuclear region to 1.19 ± 0.02. Subsequent addition of anti-PLB Fab significantly decreased F/F₀ to 1.09 ± 0.02. At 50 nM [Ca²⁺]_i, anti-PLB Fab not only decreased the overall nuclear F/F₀ previously elevated by IP₃, but also increased the amplitude and duration of spark-like nuclear Ca²⁺ release events. These nuclear Ca²⁺ releases were blocked by 2-APB. At 100 nM [Ca²⁺]_i, IP₃ induced short SCWs originating from nucleus. Anti-PLB Fab transformed those short waves into long SCWs with propagation from the nucleus into the cytosol. In contrast, neither nuclear nor cytosolic Ca²⁺ dynamics was affected by anti-PLB Fab in CMs from PLB-KO mice in all these conditions. Furthermore, in WT CMs pretreated with RyR2 blocker tetracaine, IP₃ and anti-PLB Fab still increased the magnitude of nuclear Ca²⁺ release but failed to regenerate SCWs. Finally, anti-PLB Fab increased low Ca²⁺ affinity mag-fluo 4 fluorescence intensity in the lumen of NE of nuclei isolated from WT but not in PLB-KO mice.

CONCLUSION

PLB regulates nuclear Ca²⁺ handling. By increasing Ca²⁺ uptake into lumen of the NE and perhaps other perinuclear membranes, the acute reversal of PLB inhibition decreases global Ca²⁺ concentration at rest in the nucleoplasm, and increases Ca²⁺ release into the nucleus, through mechanisms involving IP₃R and RyR2 in the vicinity.

Ondansetron blocks wild-type and p.F503L variant small-conductance Ca2+-activated K+ channels

Apamin-sensitive small-conductance Ca2+-activated K+ (SK) current ( IKAS) is encoded by Ca2+-activated K+ channel subfamily N ( KCNN) genes. IKAS importantly contributes to cardiac repolarization in conditions associated with reduced repolarization reserve. To test the hypothesis that IKAS inhibition contributes to drug-induced long QT syndrome (diLQTS), we screened for KCNN variants among patients with diLQTS, determined the properties of heterologously expressed wild-type (WT) and variant KCNN channels, and determined if the 5-HT3 receptor antagonist ondansetron blocks IKAS. We searched 2,306,335 records in the Indiana Network for Patient Care and found 11 patients with diLQTS who had DNA available in the Indiana Biobank. DNA sequencing discovered a heterozygous KCNN2 variant (p.F503L) in a 52-yr-old woman presenting with corrected QT interval prolongation at baseline (473 ms) and further corrected QT interval lengthening (601 ms) after oral administration of ondansetron. That patient was also heterozygous for the p.S38G and p.P2835S variants of the QT-controlling genes KCNE1 and ankyrin 2, respectively. Patch-clamp experiments revealed that the p.F503L KCNN2 variant heterologously expressed in human embryonic kidney (HEK)-293 cells augmented Ca2+ sensitivity, increasing IKAS density. The fraction of total F503L-KCNN2 protein retained in the membrane was higher than that of WT KCNN2 protein. Ondansetron at nanomolar concentrations inhibited WT and p.F503L SK2 channels expressed in HEK-293 cells as well as native SK channels in ventricular cardiomyocytes. Ondansetron-induced IKAS inhibition was also demonstrated in Langendorff-perfused murine hearts. In conclusion, the heterozygous p.F503L KCNN2 variant increases Ca2+ sensitivity and IKAS density in transfected HEK-293 cells. Ondansetron at therapeutic (i.e., nanomolar) concentrations is a potent IKAS blocker. NEW & NOTEWORTHY We showed that ondansetron, a 5-HT3 receptor antagonist, blocks small-conductance Ca2+-activated K+ (SK) current. Ondansetron may be useful in controlling arrhythmias in which increased SK current is a likely contributor. However, its SK-blocking effects may also facilitate the development of drug-induced long QT syndrome.

Sex-specific activation of SK current by isoproterenol facilitates action potential triangulation and arrhythmogenesis in rabbit ventricles

KEY POINTS

It is unknown if a sex difference exists in cardiac apamin-sensitive small conductance Ca²⁺ -activated K⁺ (SK) current (I_KAS ). There is no sex difference in I_KAS in the basal condition. However, there is larger I_KAS in female rabbit ventricles than in male during isoproterenol infusion. I_KAS activation by isoproterenol leads to action potential triangulation in females, indicating its abundant activation at early phases of repolarization. I_KAS activation in females induces negative Ca²⁺ -voltage coupling and promotes electromechanically discordant phase 2 repolarization alternans. I_KAS is important in the mechanisms of ventricular fibrillation in females during sympathetic stimulation.

ABSTRACT

Sex has a large influence on cardiac electrophysiological properties. Whether sex differences exist in apamin-sensitive small conductance Ca²⁺ -activated K⁺ (SK) current (I_KAS ) remains unknown. We performed optical mapping, transmembrane potential, patch clamp, western blot and immunostaining in 62 normal rabbit ventricles, including 32 females and 30 males. I_KAS blockade by apamin only minimally prolonged action potential (AP) duration (APD) in the basal condition for both sexes, but significantly prolonged APD in the presence of isoproterenol in females. Apamin prolonged APD at the level of 25% repolarization (APD₂₅ ) more prominently than APD at the level of 80% repolarization (APD₈₀ ), consequently reversing isoproterenol-induced AP triangulation in females. In comparison, apamin prolonged APD to a significantly lesser extent in males and failed to restore the AP plateau during isoproterenol infusion. I_KAS in males did not respond to the L-type calcium current agonist BayK8644, but was amplified by the casein kinase 2 (CK2) inhibitor 4,5,6,7-tetrabromobenzotriazole. In addition, whole-cell outward I_KAS densities in ventricular cardiomyocytes were significantly larger in females than in males. SK channel subtype 2 (SK2) protein expression was higher and the CK2/SK2 ratio was lower in females than in males. I_KAS activation in females induced negative intracellular Ca²⁺ -voltage coupling, promoted electromechanically discordant phase 2 repolarization alternans and facilitated ventricular fibrillation (VF). Apamin eliminated the negative Ca²⁺ -voltage coupling, attenuated alternans and reduced VF inducibility, phase singularities and dominant frequencies in females, but not in males. We conclude that β-adrenergic stimulation activates ventricular I_KAS in females to a much greater extent than in males. I_KAS activation plays an important role in ventricular arrhythmogenesis in females during sympathetic stimulation.

[Multilevel logistic regression analysis on hypercholesterolemia related risk factors among adults in China]

Objective: To investigate the prevalence of hypercholesterolemia among Chinese adults in different geographic areas, and to analyze the related factors. Methods: China Chronic and Non-Communicable Disease and Risk Factor Surveillance was conducted in 2013, based on 298 counties/districts in 31 provinces of Chinese mainland. The adults aged 18 years old were randomly selected using multi-stage stratified clustering sampling method. Information on chronic disease and risk factors was collected using face-to-face questionnaire interview and physical measurement. Blood samples were collected by local staffs. Serum total cholesterol (TC) was determined using standard method in a central laboratory. After excluding 565 participants missing key variables and 1 558 participants with abnormal TC values, a total of 174 976 participants were included. Weighted prevalence of hypercholesterolemia was calculated. Hypercholesterolemia related individual or geographic determinants were defined using multilevel logistic regression. Results: The prevalence of hypercholesterolemia in Chinese adults age 18 years old and above was 6.9% (95%CI: 6.4%-7.3%), ranged from 3.0% (95%CI: 2.5%-3.4%) in the northwest of China to 14.2% (95%CI: 12.9%-15.5%) in the south (χ(2)=183.42, P<0.001). The prevalence of hypercholesterolemia was higher in 6 provinces including Tianjin, Liaoning, Fujian, Guangdong, Guangxi, and Hainan (≥9.0%), but lower in 7 provinces including Shanxi, Shannxi, Gansu, Qinghai, Ningxia, Xinjiang, and Tibet (<3.9%). There was a 1.27 fold variation in hypercholesterolemia prevalence by provincial level, and 72.5% of the geographical variation in hypercholesterolemia prevalence was account for by area-level determinants. With multilevel logistic analysis, the individual risk factors associated with hypercholesterolemia included aging, higher education level or annual household income per capita, regular drinking, too much red meal intake, inactivity, overweight or obesity. For geographic factors, residents living at south China, counties/districts with higher urbanization rates, higher education level or lower standardized death rates were more likely to have hypercholesterolemia (all P<0.05). Conclusion: The prevalence of hypercholesterolemia was high in Chinese adults, it was different between regions and related with characteristics of population, individual behaviors and geographical regions.

[Effects of anteriolateral thigh perforator flap and fascia lata transplantation in combination with computed tomography angiography on repair of electrical burn wounds of head with skull exposure and necrosis]

Objective: To explore the effects of anteriolateral thigh perforator flap and fascia lata transplantation in combination with computed tomography angiography (CTA) on repair of electrical burn wounds of head with skull exposure and necrosis. Methods: Seven patients with head electrical burns accompanied by skull exposure and necrosis were admitted to our burn center from March 2016 to December 2017. Head CTA was performed before the operation. The diameters of the facial artery and vein or the superficial temporal artery and vein were measured, and their locations were marked on the body surface. Preoperative CTA for flap donor sites in lower extremities were also performed to track the descending branch of the lateral circumflex femoral artery with the similar diameter as the recipient vessels on the head, and their locations were marked on the body surface. Routine wound debridement and skull drilling were performed successively. The size of the wounds after debridement ranged from 12 cm×8 cm to 20 cm×12 cm, and the areas of skull exposure ranged from 8 cm×6 cm to 15 cm×10 cm. Anteriolateral thigh perforator flaps with areas from 13 cm×9 cm to 21 cm×13 cm containing 5-10 cm long vascular pedicles were designed and dissected accordingly. The fascia lata under the flap with area from 5 cm×2 cm to 10 cm×3 cm was dissected according to the length of vascular pedicle. The fascia lata was transplanted to cover the exposed skull, and the anteriolateral thigh perforator flap was transplanted afterwards. The descending branch of the lateral circumflex femoral artery and its accompanying vein of the flap were anastomosed with superficial temporal artery and vein or facial artery and vein before the suture of flap. The flap donor sites were covered by intermediate split-thickness skin graft collected from contralateral thigh or abdomen. Results: The descending branch of the lateral circumflex femoral artery and its accompanying vein were anastomosed with superficial temporal artery and vein in six patients, while those with facial artery and vein in one patient. All the flaps survived after the operation, and no vascular crisis was observed. Wound healing was satisfactory. One patient was lost to follow up. Six patients were followed up for 6 to 10 months. The patients were bald in the head operation area with acceptable appearance. No psychiatric symptom such as headache or epileptic seizure was reported. The flap donor sites were normal in appearance. The muscle strength of the lower extremities all reached grade V. The sensation and movement of the lower extremities were normal. Conclusions: Anterolateral thigh perforator flap with fascia lata transplantation can effectively repair electrical burn wounds of head with skull exposure and necrosis. The fascia lata can be used to protect the vascular pedicle of flaps, which is beneficial to the survival of the flap. Preoperative head and lower extremities CTA can provide reference for intraoperative vascular exploration in donor site and recipient area, so as to shorten operation time.

Ambipolar ferromagnetism by electrostatic doping of a manganite

Complex-oxide materials exhibit physical properties that involve the interplay of charge and spin degrees of freedom. However, an ambipolar oxide that is able to exhibit both electron-doped and hole-doped ferromagnetism in the same material has proved elusive. Here we report ambipolar ferromagnetism in LaMnO₃, with electron-hole asymmetry of the ferromagnetic order. Starting from an undoped atomically thin LaMnO₃ film, we electrostatically dope the material with electrons or holes according to the polarity of a voltage applied across an ionic liquid gate. Magnetotransport characterization reveals that an increase of either electron-doping or hole-doping induced ferromagnetic order in this antiferromagnetic compound, and leads to an insulator-to-metal transition with colossal magnetoresistance showing electron-hole asymmetry. These findings are supported by density functional theory calculations, showing that strengthening of the inter-plane ferromagnetic exchange interaction is the origin of the ambipolar ferromagnetism. The result raises the prospect of exploiting ambipolar magnetic functionality in strongly correlated electron systems.

Antiarrhythmic effects of stimulating the left dorsal branch of the thoracic nerve in a canine model of paroxysmal atrial tachyarrhythmias

BACKGROUND

Stellate ganglion nerve activity (SGNA) precedes paroxysmal atrial tachyarrhythmia (PAT) episodes in dogs with intermittent rapid left atrial (LA) pacing. The left dorsal branch of the thoracic nerve (LDTN) contains sympathetic nerves originating from the stellate ganglia.

OBJECTIVE

The purpose of this study was to test the hypothesis that high-frequency electrical stimulation of the LDTN can cause stellate ganglia damage and suppress PATs.

METHODS

We performed long-term LDTN stimulation in 6 dogs with and 2 dogs without intermittent rapid LA pacing while monitoring SGNA.

RESULTS

LDTN stimulation reduced average SGNA from 4.36 μV (95% confidence interval [CI] 4.10-4.62 μV) at baseline to 3.22 μV (95% CI 3.04-3.40 μV) after 2 weeks (P = .028) and completely suppressed all PAT episodes in all dogs studied. Tyrosine hydroxylase staining showed large damaged regions in both stellate ganglia, with increased percentages of tyrosine hydroxylase-negative cells. The terminal deoxynucleotidyl transferase dUTP nick end labeling assay showed that 23.36% (95% CI 18.74%-27.98%) of ganglion cells in the left stellate ganglia and 11.15% (95% CI 9.34%-12.96%) ganglion cells in the right stellate ganglia were positive, indicating extensive cell death. A reduction of both SGNA and heart rate was also observed in dogs with LDTN stimulation but without rapid LA pacing. Histological studies in the 2 dogs without intermittent rapid LA pacing confirmed the presence of extensive stellate ganglia damage, along with a high percentage of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells.

CONCLUSION

LDTN stimulation damages both left and right stellate ganglia, reduces left SGNA, and is antiarrhythmic in this canine model of PAT.

[Outcome of traditional growing rods for correction of apical vertebra rotation in early-onset scoliosis]

Objective: To evaluate the correction result of traditional dual growing rods on apical vertebral rotation. Methods: This study recruited 19 early-onset scoliosis patients (6 boys and 13 girls) who had received traditional dual growing rods treatment at Department of Spine Surgery, Nanjing Drum Tower Hospital from January 2009 to July 2015. The age at initial surgery was (5.7±1.7)years(range, 3 to 9 years). Measurements of primary curve magnitude, height of T(1)-S(1), apical vertebral translation(AVR), apical vertebral body-rib ratio, apical vertebral rotation, thoracic rotation and rib hump were compared between pre-operatively, post-operatively, and at latest follow-up, through a paired-t test. Pearson correlation test was used for correlation analysis between parameters. Results: All patients had a follow-up of (49.5±12.8)months(range, 24 to 71 months). A total of 111 operative procedures were performed, among which there were 92 lengthening procedures, averagely 4.8 lengthening procedures per patient. The average interval for each lengthening procedure was 10 months. The Cobb angle of primary curve was notably decreased from (66.5±13.2)° to (35.2±10.9)°(t=24.013, P<0.01), and no significant correction loss was found at the latest follow-up ((36.7±10.7)°)(t=-1.324, P=0.202). In addition, significant correction of AVR, thoracic rotation, apical vertebral translation, apical vertebra body-rib ratio, and rib hump were noted after initial surgery. Whereas, these parameters significant increased during follow-up(all P <0.05) except for thoracic rotation. Pearson correlation analysis showed that the increase of AVR during follow-up significantly correlated with change of apical vertebra translation, apical vertebral body-rib ratio, and rib hump(r=0.652, 0.814, 0.695; all P<0.05). Conclusions: Significant correction of AVR can be achieved after initial surgery in early-onset scoliosis patients treated with traditional dual growing rods. However, such a technique can hardly prevent the deterioration of AVR during follow-up.

Lamin-A/C Variants Found in Patients with Cardiac Conduction Disease Reduce Sodium Currents

Variants in the LMNA gene, which encodes Lamin-A/C, have been commonly associated with cardiac conduction system diseases usually accompanying cardiomyopathy. We have seen two unrelated patients who presented with atrioventricular block (AVB) with or without cardiomyopathy. Genetic testing identified the LMNA missense variant c.1634G>A (p.R545H) and the single nucleotide deletion c.859delG (p.A287Lfs*193). The deletion leads to a shift in the reading frame and subsequent protein truncation. Since impaired Nav1.5 function has been reported to cause AVB, we sought to investigate the effects of abnormal Lamins on Nav1.5 in HEK-293 cells using patch-clamp methods. Patch-clamp studies showed that p.R545H decreased the peak INa by approximately 70%. The voltage-dependency of steady state inactivation was rightward shifted in the cells transfected with p.R545H. The p.A287Lfs*193 also decreased the peak INa by approximately 62%. The voltagedependency of steady state inactivation was rightward shifted in the cells transfected with p.A287Lfs*193. Variants of the LMNA gene caused significant reduction of the peak INa in HEK-293 cells, which may account for the patients’ AVB.

Role of apamin-sensitive small conductance calcium-activated potassium currents in long-term cardiac memory in rabbits

BACKGROUND

Apamin-sensitive small conductance calcium-activated K current (I_KAS) is up-regulated during ventricular pacing and masks short-term cardiac memory (CM).

OBJECTIVE

The purpose of this study was to determine the role of I_KAS in long-term CM.

METHODS

CM was created with 3-5 weeks of ventricular pacing and defined by a flat or inverted T wave off pacing. Epicardial optical mapping was performed in both paced and normal ventricles. Action potential duration (APD₈₀) was determined during right atrial pacing. Ventricular stability was tested before and after I_KAS blockade. Four paced hearts and 4 normal hearts were used for western blotting and histology.

RESULTS

There were no significant differences in either echocardiographic parameters or fibrosis levels between groups. Apamin induced more APD₈₀ prolongation in CM than in normal ventricles (mean [95% confidence interval]: 9.6% [8.8%-10.5%] vs 3.1% [1.9%-4.3%]; P <.001). Apamin significantly lengthened APD₈₀ in the CM model at late activation sites, indicating significant I_KAS up-regulation at those sites. The CM model also had altered Ca²⁺ handling, with the 50% Ca²⁺ transient duration and amplitude increased at distal sites compared to a proximal site (near the pacing site). After apamin, the CM model had increased ventricular fibrillation (VF) inducibility (paced vs control: 33/40 (82.5%) vs 7/20 (35%); P <.001) and longer VF durations (124 vs 26 seconds; P <.001).

CONCLUSION

Chronic ventricular pacing increases Ca²⁺ transients at late activation sites, which activates I_KAS to maintain repolarization reserve. I_KAS blockade increases VF vulnerability in chronically paced rabbit ventricles.

[The role and significance of digital reconstruction technique in liver segments based on portal vein structure]

Objective: To study the segment of liver according to the large amount of three-dimensional(3D) reconstructive images of normal human livers and the vascular system, and to recognize the basic functional liver unit based on the anatomic features of the intrahepatic portal veins. Methods: The enhanced CT primitive DICOM files of 1 260 normal human livers from different age groups who treated from October 2013 to February 2017 provided by 16 hospitals were analyzed using the computer-aided surgery system.The 3D liver and liver vascular system were reconstructed, and the digital liver 3D model was established.The vascular morphology, anatomical features, and anatomical distributions of intrahepatic portal veins were statistically analyzed. Results: The digital liver model obtained from the 3D reconstruction of CAS displayed clear intrahepatic portal vein vessels of level four.Perform a digital liver segments study based on the analysis of level four vascular distribution areas.As the less anatomical variation of left hepatic portal vein, the liver was classified into four types of liver segmentation mainly based on right hepatic portal vein.Type A was similar to Couinaud or Cho's segmentation, containing 8 segments(537 cases, 42.62%). Type B contained 9 segments as there are three ramifications of right-anterior portal vein(464 cases, 36.82%). The main difference for Type C was the variation of right-posterior portal vein which was sector shape(102 cases, 8.10%). Type D contained the cases with special portal vein variations, which needs three-dimensional simulation to design individualized liver resection plan(157 cases, 12.46%). These results showed that there was no significant difference in liver segmental typing between genders(χ(2)=2.179, P=0.536) and did not reveal any significant difference in liver segmental typing among the different age groups(χ(2)=0.357, P=0.949). Conclusions: The 3D digital liver model can demonstrate the true 3D anatomical structures, and its spatial vascular variations.The observation of anatomic features, distribution areas of intrahepatic portal veins and individualized liver segmentation achieved via digital medical 3D visualization technology is of great value for understand the complexity of liver anatomy and to guide the precise hepatectomy.

Long-term intermittent high-amplitude subcutaneous nerve stimulation reduces sympathetic tone in ambulatory dogs

BACKGROUND

Reducing sympathetic efferent outflow from the stellate ganglia (SG) may be antiarrhythmic.

OBJECTIVE

The purpose of this study was to test the hypothesis that chronic thoracic subcutaneous nerve stimulation (ScNS) could reduce SG nerve activity (SGNA) and control paroxysmal atrial tachycardia (PAT).

METHODS

Thoracic ScNS was performed in 8 dogs while SGNA, vagal nerve activity (VNA), and subcutaneous nerve activity (ScNA) were monitored. An additional 3 dogs were used for sham stimulation as controls.

RESULTS

Xinshu ScNS and left lateral thoracic nerve ScNS reduced heart rate (HR). Xinshu ScNS at 3.5 mA for 2 weeks reduced mean average SGNA from 5.32 μV (95% confidence interval [CI] 3.89-6.75) at baseline to 3.24 μV (95% CI 2.16-4.31; P = .015) and mean HR from 89 bpm (95% CI 80-98) at baseline to 83 bpm (95% CI 76-90; P = .007). Bilateral SG showed regions of decreased tyrosine hydroxylase staining with increased terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive nuclei in 18.47% (95% CI 9.68-46.62) of all ganglion cells, indicating cell death. Spontaneous PAT episodes were reduced from 9.83 per day (95% CI 5.77-13.89) in controls to 3.00 per day (95% CI 0.11-5.89) after ScNS (P = .027). Left lateral thoracic nerve ScNS also led to significant bilateral SG neuronal death and significantly reduced average SGNA and HR in dogs.

CONCLUSION

ScNS at 2 different sites in the thorax led to SG cell death, reduced SGNA, and suppressed PAT in ambulatory dogs.

[The situation and associated factors of facility-based HIV testing among men who sex with men in Beijing]

Objective: To understand the prevalence of facility-based HIV testing and its associated factors among men who have sex with men (MSM) in Beijing city. Methods: An application-based cross-sectional survey was employed to understand HIV site test situation and associated factors. The survey was carried out from May 14(th) to 21(st), 2016. Users of a smart phone application for gay dating were recruited and those eligible for this survey were investigated with an online self-administered questionnaire. Information of demographics, sexual behaviors, facility-based HIV testing history and recreational drug abuses were collected. The multivariate logistic regression was used to make comparison among different groups and assess associated factors. Results: A total of 7 494 participants were enrolled in the survey with mean age of (28.81 ± 7.38) years, 87.14% (6 530/7 494) sought sexual partners through internet. The proportion of facility-based HIV testing in 1 year was 42.55% (3 189/7 494), MSM who were 25-29 years had higher proportion of facility-based HIV testing in 1 year, the proportion was 45.56%(1 104/2 423). Among MSM who could insist in using condom during anal sex (50.46% (1 539/3 050)), the proportion of HIV site testing in 1 year was higher. The MSM who reported seeking healthcare for symptoms of a sexually transmitted infections (STIs) in the past year or ever using recreational drug had higher proportion of facility-based HIV testing, the proportions were 56.81% (409/720) and 52.00% (1 340/4 917), respectively. Compared with alone cohabitation, cohabitating was associated with decreased odds of HIV facility-based testing in past 1 year(odds ratio (OR)= 0.79, P<0.001). Compared with homosexual sexual orientation, bisexual sexual orientation was associated with decreased odds of facility-based HIV testing (OR=0.83, P=0.004). With the increasing of number of male anal sex partners, the odds of HIV facility-based testing was increasing (OR=1.31, P<0.001) But with the decreasing of the frequency of condom using with male anal sex partners, the odds of facility-based HIV testing was decreasing (OR=0.85, P=0.014). Using recreational drugs (OR=1.36, P<0.001) and seeking healthcare for symptoms of a STI in the past 1 year (OR=1.73, P<0.001) were associated with decreased odds of HIV site testing. Conclusion: MSM in Beijing had lower proportion of facility-based HIV testing in past 1 year. Multiple anal sex partners, using recreational drugs, seeking healthcare for symptoms of a STI in the past year, cohabitating, bisexual sexual orientation, and lower frequency of condom using with male anal sex partners were associated with the odds of HIV facility-based testing in past 1 year.

[Prevalence and trend of overweight and obesity in children and adolescents in Guangdong province, 2002-2012]

Objective: To investigate the prevalence and trend of overweight and obesity in children and adolescents aged 6-17 years between 2002 and 2012 in Guangdong province. Methods: A total of 7 075 children and adolescents aged 6-17 years were selected in Guangdong for nutritional survey in 2002 and a total of 2 319 children and adolescents aged 6-17 years were selected in nine counties/districts of Guangdong for nutritional survey during 2009-2012 through multi-stage random cluster sampling. The body height and weight of all the children and adolescents were measured. Results: The result of 2009-2012 survey indicated the average prevalence of overweight and obesity in the children and adolescents surveyed were 7.3% and 4.5%, respectively. The prevalence of overweight and obesity were higher in boys (8.9% and 6.5%) than in girls (5.3% and 2.2%), in rural area (9.3% and 5.6%) than in urban area (4.7% and 3.2%). Children and adolescents aged 9-11 years had a higher overweight and obesity rates compared with other age groups. Compared with 2002, except for obesity rate in urban girls, the prevalence of overweight and obesity in children and adolescents obviously increased. The increase rate was higher in rural area than urban area and in boys than in girls. Conclusions: Compared with 2002, the prevalence of overweight and obesity in children and adolescents in Guangdong obviously increased. The prevalence was much higher in boys, those living in rural area and those aged 9-11 years, thus more attention should be paid to them.

[Analysis of the clinical and electrophysiological characteristics of multifocal motor neuropathy]

Ten patients diagnosed with multifocal motor neuropathy (MMN) were recruited in the Department of Neurology at Chinese PLA General Hospital from January 1, 2009 to August 31, 2015. The clinical and electrophysiological features were analyzed retrospectively. All patients complained of progressive asymmetric limb weakness, which was more severe in distal than in proximal. Five presented muscle atrophy. None had sensory disturbances. All suffered diminished or disappeared tendon reflex, whereas Babinski signs were negative. Multi-focal conduction block (CB) was confirmed by nerve conduction studies (NCS) in all patients and 7 showed spontaneous potentials in needle electrode electromyography. Abnormal sensory nerve conduction was seen in 3 patients. Laboratory test revealed anti-ganglioside GM1 antibody in cerebrospinal fluid (CSF) in 6 cases and elevated CSF protein in 7 cases. Limb weakness alleviated greatly in 9 cases after intravenous immunoglobulin (IVIg) treatment. But the other one reported poor response, who had long course of disease, serious limb weakness and obvious muscle atrophy. Motor nerve damage is the most important manifestation of MMN and sensory nerve damage may also appear. NCS is essential to the diagnosis of this disease, with CB as the characteristic electrophysiological feature. IVIg is an effective treatment.

[Characteristics of repetitive nerve stimulation in 53 cases of amyotrophic lateral sclerosis]

Objective: To investigate the feature of repetitive nerve stimulation (RNS) in patients with amyotrophic lateral sclerosis (ALS) and correlation between RNS and clinical features and electromyography (EMG) findings of the corresponding muscle. Methods: Needle EMG and RNS were performed in 53 patients with ALS, who were recruited into Department of Neurology of Chinese PLA general hospital during April to December in 2016. Decrement of the compond muscle action potential (CMAP) in response to RNS of different nerves and stimulus frequencies was compared. The effects of gender, age of onset, disease duration, region of onset, ALS functional rating scale-revised (ALSFRS-R) and rate of disease progression (ΔFS) on the decrement were analyzed. Results: 49.1% of patients with ALS had decremental responses to low frequency RNS (LF-RNS) in accessory nerve, which was lower in ulnar nerve (4.3%) and common peroneal nerve (2.6%). Decremental responses of accessory nerve at 3 Hz were observed in 49.1% of patients with ALS, more frequent than 30.2% at 1 Hz. None of the patients had increased responses to high frequency RNS. Patients with upper-limb-onset, longer disease duration and lower ALSFRS-R tended to have more frequent decrement of CMAP in response to RNS. The decrement with LF-RNS of accessory nerve was in concert with neurogenic damage of sternocleidomastoid muscle with needle EMG (r=0.365, P=0.007). There were 3 patients who had decremental responses to LF-RNS in accessory nerve without clinical involvement and neurogenic damage of sternocleidomastoid muscle. Conclusions: There is significant decrement of CMAP in response to LF-RNS of accessory nerve in patients with ALS, which may reveal neuromuscular junction (NMJ) impairment. It may indicated a dying-back pattern of disease progression which derived from motor neuron terminal or NMJ to neuronal soma that some patients with ALS have decremental responses in RNS without clinical involvement and neurogenic damage of sternocleidomastoid muscle.

Role of Apamin-Sensitive Calcium-Activated Small-Conductance Potassium Currents on the Mechanisms of Ventricular Fibrillation in Pacing-Induced Failing Rabbit Hearts

BACKGROUND

Ventricular fibrillation (VF) during heart failure is characterized by stable reentrant spiral waves (rotors). Apamin-sensitive small-conductance calcium-activated potassium currents (I_KAS) are heterogeneously upregulated in failing hearts. We hypothesized that I_KAS influences the location and stability of rotors during VF.

METHODS AND RESULTS

Optical mapping was performed on 9 rabbit hearts with pacing-induced heart failure. The epicardial right ventricular and left ventricular surfaces were simultaneously mapped in a Langendorff preparation. At baseline and after apamin (100 nmol/L) infusion, the action potential duration (APD₈₀) was determined, and VF was induced. Areas with a >50% increase in the maximum action potential duration (ΔAPD) after apamin infusion were considered to have a high I_KAS distribution. At baseline, the distribution density of phase singularities during VF in high I_KAS distribution areas was higher than in other areas (0.0035±0.0011 versus 0.0014±0.0010 phase singularities/pixel; P=0.004). In addition, high dominant frequencies also colocalized to high I_KAS distribution areas (26.0 versus 17.9 Hz; P=0.003). These correlations were eliminated during VF after apamin infusion, as the number of phase singularities (17.2 versus 11.0; P=0.009) and dominant frequencies (22.1 versus 16.2 Hz; P=0.022) were all significantly decreased. In addition, reentrant spiral waves became unstable after apamin infusion, and the duration of VF decreased.

CONCLUSIONS

The I_KAS current influences the mechanism of VF in failing hearts as phase singularities, high dominant frequencies, and reentrant spiral waves all correlated to areas of high I_KAS. Apamin eliminated this relationship and reduced VF vulnerability.

Small-Conductance Calcium-Activated Potassium Current in Normal Rabbit Cardiac Purkinje Cells

Background

Purkinje cells (PCs) are important in cardiac arrhythmogenesis. Whether small‐conductance calcium‐activated potassium (SK) channels are present in PCs remains unclear. We tested the hypotheses that subtype 2 SK (SK2) channel proteins and apamin‐sensitive SK currents are abundantly present in PCs.

Methods and Results

We studied 25 normal rabbit ventricles, including 13 patch‐clamp studies, 4 for Western blotting, and 8 for immunohistochemical staining. Transmembrane action potentials were recorded in current‐clamp mode using the perforated‐patch technique. For PCs, the apamin (100 nmol/L) significantly prolonged action potential duration measured to 80% repolarization by an average of 10.4 ms (95% CI, 0.11–20.72) (n=9, P=0.047). Voltage‐clamp study showed that apamin‐sensitive SK current density was significantly larger in PCs compared with ventricular myocytes at potentials ≥0 mV. Western blotting of SK2 expression showed that the SK2 protein expression in the midmyocardium was 58% (P=0.028) and the epicardium was 50% (P=0.018) of that in the pseudotendons. Immunostaining of SK2 protein showed that PCs stained stronger than ventricular myocytes. Confocal microscope study showed SK2 protein was distributed to the periphery of the PCs.

Conclusions

SK2 proteins are more abundantly present in the PCs than in the ventricular myocytes of normal rabbit ventricles. Apamin‐sensitive SK current is important in ventricular repolarization of normal PCs.

Osteoblast differentiation of rabbit adipose-derived stem cells by polyethylenimine-mediated BMP-2 gene transfection in vitro

The aim of this study was to examine the efficiency of polyethylenimine-mediated transfection of the human bone morphogenetic protein-2 (BMP-2) gene into rabbit adipose-derived stem cells (ADSCs), and its effect on osteoblast differentiation. Adipose tissue was isolated from the necks of adult Japanese white rabbits and cultured in vitro to obtain ADSCs. Gene delivery of BMP-2 was mediated by polyethylenimine and stable transformants were selected by G-418. The expression of BMP-2 mRNA was confirmed by reverse transcription-polymerase chain reaction, and of the BMP-2 protein by ELISA. Osteocalcin and collagen type I were detected by western blot and by an alkaline phosphatase kit. Alizarin red S stain was also utilized to examine osteogenesis. The non-transfected group was considered as a control. In this study, we successfully derived ADSCs from rabbit adipose tissue. Through passages 3-6, the expression of CD29 and CD44 gradually increased, whereas the expression of CD34 and CD45 gradually decreased. Both mRNA and protein expression of BMP-2 were confirmed following polyethylenimine-mediated BMP-2 gene delivery. In addition, the expression of alkaline phosphatase, osteocalcin, and collagen type I was found to be upregulated and alizarin red S staining was positive in transfected ADSCs, indicating BMP-2-induced osteogenesis. Therefore, this study determined that polyethylenimine was able to mediate BMP-2 gene delivery and induce osteogenic differentiation of ADSCs.

[Clinical and electrophysiological studies of oxaliplatin-induced peripheral neuropathy]

OBJECTIVE

To identify the sensitive scales and the early change of nerve conduction for chronic oxaliplatin-induced peripheral neuropathy (OXLIPN), and to investigate correlation between the symptoms of acute OXLIPN and chronic OXLIPN.

METHODS

Between December 2014 and August 2015, 16 colorectal cancer patients confirmed by pathology, from department of Oncology, Chinese PLA General Hospital, scheduled to receive XELOX, completed the acute neurotoxic symptoms questionnaire at the end of 1 cycles and the scales of TNSc and NCI-CTC at the baseline and the end of 4 cycles. Nerve conduction studies (bilateral peroneal nerves and sural nerves) were performed in 11 patients at the baseline and the end of 4 cycles.

RESULTS

After chemotherapy, TNSc increased 1-9 points for all cases, while NCI-CTC increased 1 point for only 9 cases, the remaining 7 cases had the same NCI-CTC score before and after chemotherapy, where TNSc increased 1-6 points. Left sural nerve a-SNAP (amplitude of sensory nerve action potential) was (15.3±5.8)μV before chemotherapy and(12.3±5.0)μV after chemotherapy. Right sural nerve a-SNAP was (17.4±8.6)μV before chemotherapy and (13.3±6.7)μV after chemotherapy. After chemotherapy, these datum were significantly reduced for left peroneal nerve distal and proximal a-CMAP (amplitude of compound muscle action potential), bilateral sural nerve a-SNAP and left sural nerve SCV (sensory conduction velocity) (P<0.05). After chemotherapy, TNSc was correlated significantly with the acute neurotoxic symptoms questionnaire (Spearman r=0.698, P=0.003).

CONCLUSIONS

TNSc is more sensitive to the severity and changes in chronic OXLIPN than NCI-CTC. Sural nerve a-SNAP has a higher sensitivity for the early changes of nerve conduction studies in chronic OXLIPN. Patients who have more symptoms of acute OXLIPN are those who eventually develop more severe chronic OXLIPN.

Association between GSTM1, GSTT1, and GSTP1 polymorphisms and gastric cancer risk, and their interactions with environmental factors

Glutathione S-transferase (GST) is an important member of phase II metabolic enzymes; GSTM1, GSTT1, and GSTP1 belong to three subfamilies of the GST enzyme. Polymorphisms in GSTM1, GSTT1, and GSTP1 could affect detoxification processes, and increase individuals' susceptibility to cancers. We aimed to investigate the association between GSTM1, GSTT1, and GSTP1 polymorphisms and the risk of gastric cancer in a Chinese population. In addition, we also examined the effect of gene-environmental interactions, and their effect on risk of this cancer. Between July 2013 and June 2015, we recruited 242 gastric cancer patients and 396 healthy controls for our study. Polymerase chain reaction-restriction fragment length polymorphism analysis was used to characterize genetic polymorphisms in GSTM1, GSTT1, and GSTP1. We observed that the Val/Val genotype of GSTP1 was associated with increased risk of gastric cancer when compared with the Ile/Ile genotype (OR = 3.19, 95%CI = 1.84-5.56). Moreover, the Val allele of GSTP1 was associated with higher susceptibility to gastric cancer as compared with the Ile allele (OR = 1.52, 95%CI = 1.19-1.93). However, GSTM1 and GSTT1 polymorphisms did not affect the development of gastric cancer. In conclusion, our study indicated that GSTP1 Ile105Val, but not GSTM1 and GSTT1 polymorphisms, was associated with risk of gastric cancer.

Effects of renal sympathetic denervation on the stellate ganglion and brain stem in dogs

BACKGROUND

Renal sympathetic denervation (RD) is a promising method of neuromodulation for the management of cardiac arrhythmia.

OBJECTIVE

We tested the hypothesis that RD is antiarrhythmic in ambulatory dogs because it reduces the stellate ganglion nerve activity (SGNA) by remodeling the stellate ganglion (SG) and brain stem.

METHODS

We implanted a radiotransmitter to record SGNA and electrocardiogram in 9 ambulatory dogs for 2 weeks, followed by a second surgery for RD and 2 months SGNA recording. Cell death was probed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay.

RESULTS

Integrated SGNA at baseline and 1 and 2 months after RD were 14.0 ± 4.0, 9.3 ± 2.8, and 9.6 ± 2.0 μV, respectively (P = .042). The SG from RD but not normal control dogs (n = 5) showed confluent damage. An average of 41% ± 10% and 40% ± 16% of ganglion cells in the left and right SG, respectively, were TUNEL positive in RD dogs compared with 0% in controls dogs (P = .005 for both). The left and right SG from RD dogs had more tyrosine hydroxylase-negative ganglion cells than did the left SG of control dogs (P = .028 and P = .047, respectively). Extensive TUNEL-positive neurons and glial cells were also noted in the medulla, associated with strongly positive glial fibrillary acidic protein staining. The distribution was heterogeneous, with more cell death in the medial than lateral aspects of the medulla.

CONCLUSION

Bilateral RD caused significant central and peripheral sympathetic nerve remodeling and reduced SGNA in ambulatory dogs. These findings may in part explain the antiarrhythmic effects of RD.

[A preliminary discussion on the contents and value of Shi er mai (Twelve Channels) and Bie mai (Allo-channels), the medical bamboo slips unearthed from Han tomb in Laoguanshan of Chengdu]

The 52 medical bamboo slips entitled Si er ma (Twelve Channels) and Bie mai (Allo-channels) , unearthed from Han tomb in Laoguanshan, are the exclusive medical books concerning channels. Shi er mai is the first work bearing the term " heart dominating channel" , and the running pathways and manifestations of 12 channels. This book could be the major original sources of the 12-channel theories described in the Chapter of Jing mai (Channels) of Ling shu (Miraculous Pivot) . While Bie mai suggests the coexistence of the multi-channel systems at the time when the book was compiled and, together with the 12 "channel" , and 3 "branched collaterals" , these 2 books represent the original condition before the establishment of the mode of channel circulation in Ling shu, and is significant to explore the nature and origin of channel.

[Cadmium burden and renal dysfunction among residents in cadmium-polluted areas: A 3-year follow-up study]

OBJECTIVE

To investigate dynamic change of cadmium body burden and renal dysfunction among residents living in cadmium-polluted areas.

METHODS

From April to July of 2011, the cadmium-polluted areas of northern Guangdong province in China was chosen as the study site. Based on the levels of cadmium pollution in soil and rice, the survey areas were divided into low exposed group (average concentration of cadmium was 0.15-0.40 mg/kg, 0.5-1.0 mg/kg in rice and soil, respectively) and high exposed group (average concentration of cadmium was >0.40 mg/kg, >1.0 mg/kg in rice and soil, respectively). Stratified random sampling and cluster sampling method of epidemiological investigations were carried out among 414 local residents who lived in cadmium exposure areas for more than 15 years, aged above 40, and without occupational cadmium exposure, including 168 and 246 residents in low and high exposed group, respectively. From March to June of 2014, 305 respondents of those who participated in 2011 were successfully traced, including 116 and 189 respondents in low and high exposed group, respectively. We used health questionnaires to acquire their health status. Home-harvested rice and vegetable samples were collected using quartering method for detection of cadmium level, including 190 rice samples, 161 vegetable samples in 2011 and 190 rice samples, 153 vegetable samples in 2014. Urine specimens of residents were collected for the detection of urinary cadmium and creatinine as well as renal dysfunction biomarkers, namely, N-acetyl-beta-D-glucosamidase (NAG) and β2-microglobulin (β2-MG), respectively. In 2011 and 2014, Chi-square test was used to investigate the differences of abnormality of cadmium concentration in rice, vegetables and urinary cadmium, β2-MG, and NAG that were expressed as odds ratio(OR) and 95% confidence intervals (95%CI).

RESULTS

In 2011 and 2014, cadmium concentration P50 (P25-P75) in rice was 0.43 (0.17-1.10) mg/kg, and 0.42 (0.20-1.14) mg/kg, respectively (Z=-0.77,P=0.440). In 2011 and 2014, cadmium concentrations P50 (P25-P75) in vegetables were 0.13 (0.07-0.34) mg/kg, and 0.25(0.12-0.59) mg/kg, respectively, with abnormal rates of 38.5%(62/161) and 60.8%(93/153), respectively. In 2014, both average concentration and abnormal rate of cadmium in vegetables were higher than those in 2011 (Z=-4.69, P<0.001 and χ(2)=15.58,P<0.001). Concentrations of urinary cadmium P50 (P25-P75) in high exposed group were 7.90 (3.96-14.91) μg/g creatinine, 8.64 (4.56-17.60) μg/g creatinine in 2011 and 2014, respectively. Contrary to that in 2011, urinary cadmium of high exposed group was significantly increased in 2014 (Z=-2.80, P=0.005). In 2011 and 2014, concentrations of β2-MG, NAG P50 (P25-P75) were 0.15(0.07-0.29) μg/g creatinine, 0.15 (0.07-0.45) μg/g creatinine, and 7.12 (5.05-10.65) U/g creatinine, 13.55(9.1-19.84) U/g creatinine, respectively, with abnormal rates of 7.5% (23/305), 15.1% (46/305), 8.2% (25/305) , and 33.8% (103/305), respectively. Compared with baseline in 2011, average concentrations of β2-MG, NAG significantly increased in 2014 (Z=-2.263, P=0.024 and Z=-12.52, P<0.001), and abnormal rates of β2-MG, NAG were also higher in 2014 (χ(2)=15.61 , P<0.001 and χ(2)=64.72, P<0.001), with odds ratio(OR) of 2.00 (95%CI:1.23-3.24) and 4.12 (95%CI:2.87-5.92).

CONCLUSION

Environmental cadmium pollution of crops such as rice and vegetables in survey areas continued to remain high. Body burden of cadmium might kept at sustainably high levels and renal dysfunction was worsened after continuous, long-term cadmium exposure. Our results suggested that NAG might be more sensitive than β2-MG to serve as an indicator for an individual's future tubular function.