Characterization of a multiprotein complex involved in excitation-transcription coupling of skeletal muscle

BACKGROUND

Electrical activity regulates the expression of skeletal muscle genes by a process known as "excitation-transcription" (E-T) coupling. We have demonstrated that release of adenosine 5'-triphosphate (ATP) during depolarization activates membrane P2X/P2Y receptors, being the fundamental mediators between electrical stimulation, slow intracellular calcium transients, and gene expression. We propose that this signaling pathway would require the proper coordination between the voltage sensor (dihydropyridine receptor, DHPR), pannexin 1 channels (Panx1, ATP release conduit), nucleotide receptors, and other signaling molecules. The goal of this study was to assess protein-protein interactions within the E-T machinery and to look for novel constituents in order to characterize the signaling complex.

METHODS

Newborn derived myotubes, adult fibers, or triad fractions from rat or mouse skeletal muscles were used. Co-immunoprecipitation, 2D blue native SDS/PAGE, confocal microscopy z-axis reconstruction, and proximity ligation assays were combined to assess the physical proximity of the putative complex interactors. An L6 cell line overexpressing Panx1 (L6-Panx1) was developed to study the influence of some of the complex interactors in modulation of gene expression.

RESULTS

Panx1, DHPR, P2Y2 receptor (P2Y2R), and dystrophin co-immunoprecipitated in the different preparations assessed. 2D blue native SDS/PAGE showed that DHPR, Panx1, P2Y2R and caveolin-3 (Cav3) belong to the same multiprotein complex. We observed co-localization and protein-protein proximity between DHPR, Panx1, P2Y2R, and Cav3 in adult fibers and in the L6-Panx1 cell line. We found a very restricted location of Panx1 and Cav3 in a putative T-tubule zone near the sarcolemma, while DHPR was highly expressed all along the transverse (T)-tubule. By Panx1 overexpression, extracellular ATP levels were increased both at rest and after electrical stimulation. Basal mRNA levels of the early gene cfos and the oxidative metabolism markers citrate synthase and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) were significantly increased by Panx1 overexpression. Interleukin 6 expression evoked by 20-Hz electrical stimulation (270 pulses, 0.3 ms each) was also significantly upregulated in L6-Panx1 cells.

CONCLUSIONS

We propose the existence of a relevant multiprotein complex that coordinates events involved in E-T coupling. Unveiling the molecular actors involved in the regulation of gene expression will contribute to the understanding and treatment of skeletal muscle disorders due to wrong-expressed proteins, as well as to improve skeletal muscle performance.

Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium

Cannabis is the most widely produced and consumed illicit psychoactive substance worldwide. Occasional cannabis use can progress to frequent use, abuse and dependence with all known adverse physical, psychological and social consequences. Individual differences in cannabis initiation are heritable (40-48%). The International Cannabis Consortium was established with the aim to identify genetic risk variants of cannabis use. We conducted a meta-analysis of genome-wide association data of 13 cohorts (N=32 330) and four replication samples (N=5627). In addition, we performed a gene-based test of association, estimated single-nucleotide polymorphism (SNP)-based heritability and explored the genetic correlation between lifetime cannabis use and cigarette use using LD score regression. No individual SNPs reached genome-wide significance. Nonetheless, gene-based tests identified four genes significantly associated with lifetime cannabis use: NCAM1, CADM2, SCOC and KCNT2. Previous studies reported associations of NCAM1 with cigarette smoking and other substance use, and those of CADM2 with body mass index, processing speed and autism disorders, which are phenotypes previously reported to be associated with cannabis use. Furthermore, we showed that, combined across the genome, all common SNPs explained 13-20% (P<0.001) of the liability of lifetime cannabis use. Finally, there was a strong genetic correlation (rg=0.83; P=1.85 × 10(-8)) between lifetime cannabis use and lifetime cigarette smoking implying that the SNP effect sizes of the two traits are highly correlated. This is the largest meta-analysis of cannabis GWA studies to date, revealing important new insights into the genetic pathways of lifetime cannabis use. Future functional studies should explore the impact of the identified genes on the biological mechanisms of cannabis use.

Related factors with substance use in old adults

Intro

Substance use disorder is a growing phenomenon among the elderly. It is undervalued, misidentified, underdiagnosed and poorly treated.

Aim

Study prevalence, characteristics and risk factors associated with drug use among the elderly.

Method

A 6-month prospective study of substance use in elderly patients (65+) who attended the addiction and dual diagnosis unit, Vall d’Hebron University Hospital.

Results

Fifty-nine patients evaluated, mean age 70.04 years, 60% men. A total of 49.1% are married, 35.8% divorced and 53.8% live with a partner and/or children. A total of 67.3% have basic studies and 78.8% are pensioners. A total of 82.7% have no criminal record.

Medical comorbidity presents in 90.4% of the sample, psychiatric and addictive family background in 42.3% and 37.3%. A total of 67.3% have comorbid Axis I (mainly affective disorders) and 25% Axis II (cluster B most). A total of 7.7% attempted suicide at least once.

The main substance is alcohol (76.9%), followed by prescription drugs (19.3%). A total of 28.8% are multi-drug users. A total of 67.3% have used tobacco in their life and 63.5% are currently dependent. The average age of onset for a disorder for any substance consumption is 28.19, being lower for alcohol and illegal substances and higher for prescription drugs.

A total of 61.5% have gone through treatment before but only 32.7% has been admitted because of addiction. The adherence rate is 90.4% and the relapse rate 8.3% at first month and 13% at 6 months.

Conclusions

Old adults present differences compared to overall drug user population: prevalence by gender is almost equal, lower Axis II, less multi-drug consumption and both dropout and relapse rate are drastically lower.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Risk factors for accidents among cocaine-dependent patient seeking treatment

Introduction

Accident rate have a high social cost. Cocaine consumption increases the risk of traffic crashes (Monras, 2011; Fierro, 2011). However, there is not extensively studies in addicts.

Objective

Compare and analyze the history of accidents and risk behaviors while driving in cocaine dependent patients (DC) and of other substances (OtherD).

Methods

One hundred and eighty-two patients seeking treatment since January 2014 to September 2015. Sociodemographic and accident-related variables were collected, also administered the MDBQ. Descriptive analysis and bivariate analysis using Chi-square test for categorical variables and Student t test was performed for quantitative.

Results

Of women, 30.3%, and 69.7% men, mean age 43.67 years (SD = 13). 65.6% currently driving or above. 45.2% DC vs. 54.8 DOther (35.6% alcohol, cannabis 8.3%, 5.8% opioid and 5.1% other drugs).

Comparing accident rate on the DC is a tendency to have suffered more accidents (χ2: 2.62 P=.072). Patients addicted to cocaine referred further potentially dangerous activities both under the influence of consumption (65.9% vs. 33.3%) and abstinence (41.7% vs. 12%).

As for the results of MDBQ, it has been detected that cocaine addicts show more errors and traffic violations. No differences in the lapses identified by patients of different groups.

Conclusion

Patients with cocaine dependence have more accidents, reduced risk perception and recognize more mistakes and traffic violations. Cocaine implies a high risk of road accidents and exposure to high-risk situations compared to the use of other substances.

References not available.

Disclosure of interest

The authors have not supplied their declaration of competing interest.

Abstract P3-07-42: Predicting outcome and benefit to first-line bevacizumab in advanced/metastatic hormone receptor (HR)+/HER2-negative breast cancer (BC) treated with endocrine therapy: A correlative science study from the LEA phase III clinical trial (GEICAM/2006-11_GBG 051)

Introduction: The role of bevacizumab in combination with chemotherapy in metastatic BC is controversial, and no biomarker exists as of today that predicts benefit to this agent. In the LEA clinical trial, a numerical, statistically non-significant benefit from the addition of bevacizumab to endocrine therapy (ET) was observed in the first-line metastatic setting (18.4 vs. 13.8 months of Progression-Free Survival (PFS), p=0.14). Here, we explored various gene expression-based predictors of outcome and benefit to bevacizumab.

Methods and materials: LEA trial randomized 380 patients with HR+/HER2- advanced disease to bevacizumab in combination with ET (ET+B) vs. ET alone. Primary endpoint was PFS. Expression of BC selected genes was evaluated in formalin-fixed paraffin-embedded (FFPE) primary tumors using the nCounter platform from patients randomized in Spain that consent for biomarker analyses. The following variables were evaluated: 1) research-based PAM50 intrinsic subtypes (categorical variable; Luminal A, Luminal B, HER2-enriched, Basal-like and Normal-like); 2) research-based PAM50 signatures (continuous variable; scores showing the distant of the gene expression values of an individual sample compared to the centroid gene values for each PAM50 intrinsic subtype); 3) risk of recurrence (ROR) groups (low, medium and high); 4) the 13-gene hypoxia/VEGF signature (continuous); and 5) Ki67 by immunohistochemistry (continuous). Uni- and multivariable Cox models for PFS were used to test the prognostic significance of each variable. To determine whether each variable is predictive of bevacizumab benefit, we tested the interaction term of each variable by treatment arm in a Cox model.

Results: Tumor samples from 103 patients were analyzed: 55 (53%) in ET+B arm and 49 (47%) in ET arm. Subtype distribution was as follows: 57 (55.3%) Luminal A, 32 (31.1%) Luminal B, 5 (4.9%) HER2-enriched, 1 (1.0%) Basal-like, and 8 (7.8%) normal-like. In a univariate analysis, Luminal B tumors had a poorer outcome using Luminal A as reference (13.8 vs. 21.3 months, respectively; (hazard ratio, HR=1.80, 95% CI 1.10-2.95, p=0.019). Concordant with this finding, Luminal A signature was associated with a better outcome. Similarly, ROR-P high group showed a poorer outcome than ROR-P low group (8.5 vs. 19.4 months; HR=2.88, 95% CI 1.30-6.35, p=0.009). Neither VEGF-13 signature nor Ki67 were found to be associated with PFS. Similar findings were obtained after adjustment for treatment, age, previous ET, ECOG, visceral disease and number of metastatic sites. In terms of treatment benefit, the HER2-enriched signature was the only variable found predictive of bevacizumab PFS benefit in univariate (p=0.010) and multivariate (p=0.015) analyses.

Conclusions: In advanced HR+/HER2- disease, intrinsic subtype (i.e. Luminal A vs. B) independently predicts PFS following first-line ET. In addition, HR+/HER2-negative tumors with high expression of the HER2-enriched signature, a biomarker of estrogen-independence, benefit the most from bevacizumab. Further validation of these prognostic and predictive biomarkers is warranted.

Citation Format: Prat A, de la Haba-Rodriguez J, Guerrero Á, García-Sáenz JA, Morales S, Antón A, Muñoz M, Ramos M, Martínez-Jáñez N, Margelí M, Servitja S, Rojo F, Galván P, González S, Cruz J, Sánchez-Rovira P, Perelló A, Rodríguez-Martin C, Casas M, Carrasco E, Caballero R, Martín M. Predicting outcome and benefit to first-line bevacizumab in advanced/metastatic hormone receptor (HR)+/HER2-negative breast cancer (BC) treated with endocrine therapy: A correlative science study from the LEA phase III clinical trial (GEICAM/2006-11_GBG 051). [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-07-42.

Bipolar disorder with comorbid attention-deficit and hyperactivity disorder. Main clinical features and clues for an accurate diagnosis

OBJECTIVE

To study the prevalence of attention-deficit and hyperactivity disorder (ADHD) in adult patients with bipolar disorder (BD) and identify differential clinical features for a better diagnosis.

METHOD

A total of 163 euthymic bipolar out-patients were screened for ADHD with the ASRS.V1 and the WURS at a BD Unit. Patients with a positive screening were assessed with the CAADID, at an ADHD unit. Sociodemographic and clinical features of the groups with and without ADHD were compared.

RESULTS

Lifetime prevalence of comorbid ADHD was 17.9% (10.5% for adult ADHD and 7.4% for childhood ADHD). The BD + ADHD group showed more suicidal behaviour although less severe. Comorbidity was also more common, especially regarding substance use disorders. Nevertheless, these patients did not show more affective episodes or hospitalizations and suffered more atypical but less melancholic depression. However, they required more treatment with psychotherapy and valproate. One-third of positive screenings at the ASRS were false; a severe course of BD was the hallmark of this subgroup.

CONCLUSION

Adult patients with BD and ADHD show differential clinical features, but not a more severe course of BD. Comorbidity with substance abuse is a big issue, deserving special clinical attention. Better screening tools are necessary to avoid overdiagnosis of comorbid ADHD in BD.

[Clinical and psychopathological factors associated with impulse control disorders in Parkinson's disease]

INTRODUCTION

Impulse control disorders (ICD) constitute a complication that may arise during the course of Parkinson's disease (PD). Several factors have been linked to the development of these disorders, and their associated severe functional impairment requires specific and multidisciplinary management. The objective of this study was to evaluate the frequency of ICDs and the clinical and psychopathological factors associated with the appearance of these disorders.

METHODS

Cross-sectional, descriptive, and analytical study of a sample of 115 PD patients evaluated to determine the presence of an ICD. Clinical scales were administered to assess disease severity, personality traits, and presence of psychiatric symptoms at the time of evaluation.

RESULTS

Of the 115 patients with PD, 27 (23.48%) displayed some form of ICD; hypersexuality, exhibited by 14 (12.2%), and binge eating, present in 12 (10.1%), were the most common types. Clinical factors associated with ICD were treatment with dopamine agonists (OR: 13.39), earlier age at disease onset (OR: 0.92), and higher score on the UPDRS-I subscale; psychopathological factors with a significant association were trait anxiety (OR: 1.05) and impulsivity (OR: 1.13).

CONCLUSIONS

ICDs are frequent in PD, and treatment with dopamine agonists is the most important risk factor for these disorders. High impulsivity and anxiety levels at time of evaluation, and younger age at disease onset, were also linked to increased risk. However, presence of these personality traits prior to evaluation did not increase risk of ICD.

Psychiatrists admitted to a physicians' health programme

BACKGROUND

Psychiatrists are at a high risk of becoming mentally ill at some point during their careers.

AIMS

To compare the profile of psychiatrists admitted to the Barcelona Physicians' Health Programme (PHP) with other sick doctors in the programme.

METHODS

A retrospective case review of electronic medical records was conducted for physicians registered at the 'Colegio de Médicos' in Barcelona and consecutively admitted to the Barcelona PHP from January 1998 until December 2013.

RESULTS

One thousand two hundred eighteen records were reviewed. The 72 psychiatrists admitted to the programme were not statistically different from the other physicians in gender (54% versus 51% women), primary diagnosis (34% non-substance use mental disorders versus 29% substance use disorders), prevalence of adjustment disorders and median length of their first treatment episode (9.0 versus 8.4 months). Psychiatrists were significantly older (mean age 53 versus 50 years; t = 2.12; P < 0.05), more frequently had inpatient treatment during their first treatment episode (17% versus 10%; χ (2) = 4.57, P < 0.05) and had more referred (rather than self-referred) admissions (22% versus 13%; χ (2) = 4.57, P < 0.05) than other physicians. However, only the type of referral played a significant role when considering the simultaneous effect of all relevant variables (Wald = 4.43; P < 0.05).

CONCLUSIONS

Psychiatrists with mental disorders may be more reluctant to ask for help from a PHP voluntarily than other physicians. Members of this professional group should be encouraged to seek help when affected by mental distress or addiction problems.

ROS Production via P2Y1-PKC-NOX2 Is Triggered by Extracellular ATP after Electrical Stimulation of Skeletal Muscle Cells

During exercise, skeletal muscle produces reactive oxygen species (ROS) via NADPH oxidase (NOX2) while inducing cellular adaptations associated with contractile activity. The signals involved in this mechanism are still a matter of study. ATP is released from skeletal muscle during electrical stimulation and can autocrinely signal through purinergic receptors; we searched for an influence of this signal in ROS production. The aim of this work was to characterize ROS production induced by electrical stimulation and extracellular ATP. ROS production was measured using two alternative probes; chloromethyl-2,7- dichlorodihydrofluorescein diacetate or electroporation to express the hydrogen peroxide-sensitive protein Hyper. Electrical stimulation (ES) triggered a transient ROS increase in muscle fibers which was mimicked by extracellular ATP and was prevented by both carbenoxolone and suramin; antagonists of pannexin channel and purinergic receptors respectively. In addition, transient ROS increase was prevented by apyrase, an ecto-nucleotidase. MRS2365, a P2Y₁ receptor agonist, induced a large signal while UTPyS (P2Y₂ agonist) elicited a much smaller signal, similar to the one seen when using ATP plus MRS2179, an antagonist of P2Y₁. Protein kinase C (PKC) inhibitors also blocked ES-induced ROS production. Our results indicate that physiological levels of electrical stimulation induce ROS production in skeletal muscle cells through release of extracellular ATP and activation of P2Y1 receptors. Use of selective NOX2 and PKC inhibitors suggests that ROS production induced by ES or extracellular ATP is mediated by NOX2 activated by PKC.

ATP signaling in skeletal muscle: from fiber plasticity to regulation of metabolism

Tetanic electrical stimulation releases adenosine triphosphate (ATP) from muscle fibers through pannexin-1 channels in a frequency-dependent manner; extracellular ATP activates signals that ultimately regulate gene expression and is able to increase glucose transport through activation of P2Y receptors, phosphatidylinositol 3-kinase, Akt, and AS160. We hypothesize that this mechanism is an important link between exercise and the regulation of muscle fiber plasticity and metabolism.

Potential role of skeletal muscle glucose metabolism on the regulation of insulin secretion

Pancreatic beta cells sense glucose flux and release as much insulin as required in order to maintain glycaemia within a narrow range. Insulin secretion is regulated by many factors including glucose, incretins, and sympathetic and parasympathetic tones among other physiological factors. To identify the mechanisms linking obesity-related insulin resistance with impaired insulin secretion represents a central challenge. Recently, it has been argued that a crosstalk between skeletal muscle and the pancreas may regulate insulin secretion. Considering that skeletal muscle is the largest organ in non-obese subjects and a major site of insulin- and exercise-stimulated glucose disposal, it appears plausible that muscle might interact with the pancreas and modulate insulin secretion for appropriate peripheral intracellular glucose utilization. There is growing evidence that muscle can secrete so-called myokines that can have auto/para/endocrine actions. Although it is unclear in which direction they act, interleukin-6 seems to be a possible muscle-derived candidate protein mediating such inter-organ communication. We herein review some of the putative skeletal muscle-derived factors mediating this interaction. In addition, the evidence coming from in vitro, animal and human studies that support such inter-organ crosstalk is thoroughly discussed.

Early-age clinical and developmental features associated to Substance Use Disorders in Attention-Deficit/Hyperactivity Disorder in Adults

OBJECTIVE

The main objective was to explore early-age conditions associated to Substance Use Disorders (SUD) in adults with Attention Deficit/Hyperactivity Disorder (ADHD); secondly, to determine which of those conditions are specific to ADHD subjects; and finally, to compare ADHD and non-ADHD subjects in terms of SUD lifetime prevalence and professional, social and personal adjustment.

METHOD

Comparison between ADHD adults with (n=236) and without lifetime SUD (n=309) regarding clinical characteristics of ADHD, externalization disorders, temperamental traits, environmental factors, academic history and family psychiatric history; secondly, ADHD subjects were compared to a non-ADHD group (n=177) concerning those variables.

RESULTS

The following variables were found to be positively associated to SUD in ADHD subjects: ADHD severity, CD and ODD comorbidities, temperamental characteristics ("fearful", "accident prone" and "frequent temper tantrums"), "sexual abuse", "be suspended from school", family history of SUD and ADHD, and male gender; ADHD inattentive subtype and "fearful" were inversely associated to SUD. From those variables, "frequent temper tantrums" was also associated to SUD in non-ADHD subjects. ADHD subjects had higher prevalence of lifetime SUD and greater professional, social and personal impairment than non-ADHD subjects.

CONCLUSION

Findings suggest a significant association between ADHD, SUD and early-age conditions, such as CD and ODD comorbidity; other variables from childhood, namely, ADHD subtype, temper characteristics ("fearful", "accident prone"), "sexual abuse", "be suspended from school" and family history of ADHD are associated to SUD in ADHD subjects, but not in non-ADHD subjects. Moreover, this study confirms both the higher prevalence of lifetime SUD and greater professional, social and personal impairment in ADHD subjects than in non-ADHD subjects.

Effectiveness of the 7-valent pneumococcal conjugate vaccine against vaccine-type invasive disease among children in Uruguay: an evaluation using existing data

The 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the routine immunization program in Uruguay in March 2008 with a 2-dose primary series (given at 2 and 4 months) plus a booster (at 12 months) and a catch-up campaign (two doses given at 15 and 17 months). We used a case-control methodology and existing laboratory surveillance and immunization registry data from Uruguay to evaluate PCV7 effectiveness against vaccine-type invasive pneumococcal disease (VT-IPD). Cases of VT-IPD (with pneumococcus obtained from a normally sterile site) were identified through the National Reference Laboratory. Age- and neighborhood-matched controls were obtained through a national immunization registry in which all children are enrolled at birth regardless of vaccine receipt; all eligible controls were included. Immunization status of cases and controls was assessed through the immunization registry, and conditional logistic regression was used to calculate PCV7 effectiveness. Between April 2008 and February 2010, 44 cases of VT-IPD among children<5 years were identified; 43 (98%) of those children were located in the registry. Among located case patients, 7 (16.3%) were age-eligible to have received at least one dose of PCV7. A total of 637 matched controls were included. Vaccine effectiveness was 91.3% (95% CI: 46.4, 98.6) for ≥ 1 PCV7 doses and 94.8% (95% CI: 43.1, 99.5) for ≥ 2 PCV7 doses. Using existing data we demonstrated high effectiveness of PCV7 against VT-IPD in Uruguay-a middle-income country using a 2-dose primary series plus a booster dose and a limited catch-up campaign. These data also highlight the utility of surveillance and high-quality immunization registries for evaluating the effectiveness of vaccines.