Pro-survival function of MEF2 in cardiomyocytes is enhanced by β-blockers

β1-Adrenergic receptor (β1-AR) stimulation increases apoptosis in cardiomyocytes through activation of cAMP/protein kinase A (PKA) signaling. The myocyte enhancer factor 2 (MEF2) proteins function as important regulators of myocardial gene expression. Previously, we reported that PKA signaling directly represses MEF2 activity. We determined whether (a) MEF2 has a pro-survival function in cardiomyocytes, and (b) whether β-adrenergic/PKA signaling modulates MEF2 function in cardiomyocytes. Initially, we observed that siRNA-mediated gene silencing of MEF2 induces cardiomyocyte apoptosis as indicated by flow cytometry. β1-AR activation by isoproterenol represses MEF2 activity and promotes apoptosis in cultured neonatal cardiomyocytes. Importantly, β1-AR mediated apoptosis was abrogated in cardiomyocytes expressing a PKA-resistant form of MEF2D (S121/190A). We also observed that a β1-blocker, Atenolol, antagonizes isoproterenol-induced apoptosis while concomitantly enhancing MEF2 transcriptional activity. β-AR stimulation modulated MEF2 cellular localization in cardiomyocytes and this effect was reversed by β-blocker treatment. Furthermore, Kruppel-like factor 6, a MEF2 target gene in the heart, functions as a downstream pro-survival factor in cardiomyocytes. Collectively, these data indicate that (a) MEF2 has an important pro-survival role in cardiomyocytes, and (b) β-adrenergic signaling antagonizes the pro-survival function of MEF2 in cardiomyocytes and β-blockers promote it. These observations have important clinical implications that may contribute to novel strategies for preventing cardiomyocyte apoptosis associated with heart pathology.

Psychomotor effects of mixed organic solvents on rubber workers

BACKGROUND

Exposure to organic solvents is common among workers.

OBJECTIVE

To assess neurobehavioral effects of long-term exposure to organic solvents among rubber workers in Tehran, Iran.

METHODS

Across-sectional study was conducted on 223 employees of a rubber industry. The participants completed a data collection sheet on their occupational and medical history, and demographic characteristics including age, work experience, education level; they performed 6 psychiatric tests on the neurobehavioral core test battery (NCTB) that measure simple reaction time, short-term memory (digit span, Benton), eye-hand coordination (Purdue pegboard, pursuit aiming), and perceptual speed (digit symbol).

RESULTS

Workers exposed and not exposed to organic solvents had similar age and education distribution. The mean work experience of the exposed and non-exposed workers was 5.9 and 4.4 years, respectively. The exposed workers had a lower performance compared to non-exposed workers in all psychomotor tests. After controlling for the confounders by logistic regression analysis, it was found that exposure to organic solvents had a significant effect on the results of digit symbols, digit span, Benton, aiming, and simple reaction time tests. No significant effect was observed in pegboard test.

CONCLUSION

Occupational exposure to organic solvent can induce subtle neurobehavioral changes among workers exposed to organic solvents; therefore, periodical evaluation of the central nervous system by objective psychomotor tests is recommended among those who are chronically exposed to organic solvents.

Cross-talk between glycogen synthase kinase 3β (GSK3β) and p38MAPK regulates myocyte enhancer factor 2 (MEF2) activity in skeletal and cardiac muscle

Characterizing the signaling network that controls MEF2 transcription factors is crucial for understanding skeletal and cardiac muscle gene expression. Glycogen synthase kinase 3β (GSK3β) regulates MEF2 activity indirectly through reciprocal regulation of p38MAPK. Cross-talk between GSK3β and p38MAPK regulates MEF2 activity in skeletal and cardiac muscle. Understanding cross-talk in the signaling network converging at MEF2 control has therapeutic implications in cardiac and skeletal muscle pathology. Glycogen synthase kinase 3β (GSK3β) is a known regulator of striated muscle gene expression suppressing both myogenesis and cardiomyocyte hypertrophy. Since myocyte enhancer factor 2 (MEF2) proteins are key transcriptional regulators in both systems, we assessed whether MEF2 is a target for GSK3β. Pharmacological inhibition of GSK3β resulted in enhanced MEF2A/D expression and transcriptional activity in skeletal myoblasts and cardiac myocytes. Even though in silico analysis revealed GSK3β consensus (S/T)XXX(S/T) sites on MEF2A, a subsequent in vitro kinase assay revealed that MEF2A is only a weak substrate. However, we did observe a posttranslational modification in MEF2A in skeletal myoblasts treated with a GSK3β inhibitor which coincided with increased p38MAPK phosphorylation, a potent MEF2A activator, indicating that GSK3β inhibition may de-repress p38MAPK. Heart specific excision of GSK3β in mice also resulted in up-regulation of p38MAPK activity. Interestingly, upon pharmacological p38MAPK inhibition (SB203580), GSK3β inhibition loses its effect on MEF2 transcriptional activity suggesting potent cross-talk between the two pathways. Thus we have documented that cross-talk between p38MAPK and GSK3β signaling converges on MEF2 activity having potential consequences for therapeutic modulation of cardiac and skeletal muscle gene expression.

Glanders outbreak at Tehran Zoo, Iran

BACKGROUND AND OBJECTIVES

In December 2010 four, lions and one tiger died at the Tehran zoo. Out of all samples, Burkholderia mallei (causative agent of Glanders) was isolated just from ulcer sample of the tiger which was imported to Iran from Russia.

MATERIALS AND METHODS

One nasal swab from a tiger and fifteen blood samples with anticoagulant belonging to one tiger and fourteen lions (four dead lions and eleven live lions) were collected and were inoculated directly onto the selective media. The isolate was identified by morphological and biochemical and API BBL tests and PCR using specific primers (Bma- IS407-flip). The standard (Razi Type Culture Collection RTCC: 2375) and tiger isolates were inoculated into 2 guinea pigs. All residue solipeds and carnivores were checked by Malleination test and Complement Fixation (CF) Test respectively.

RESULTS

One isolate of B. mallei was isolated from tiger's nasal swab. Both of B.mallei strains were recovered from inoculated animals. All of solipeds were negative by malleination test, however, 11 lions including 4 dead and 7 live lions out of 14 lions were positive in CF test for Glanders and all were put down by the authorities.

CONCLUSION

Active surveillance of Glanders is essential for solipeds, especially it's more important while being used to feed valuable carnivores like lions and tigers. Therefore, a reliable test like malleination must be carried out twice (first before transferring and one month after quarantine). Both test results should be negative for use for feeding.

Impact of preconception health education on health locus of control and self-efficacy in women

The preconception period is an ideal opportunity to optimize women's health. This study of women attending premarital clinics in the Islamic Republic of Iran aimed to evaluate the impact of a health education workshop on their health locus of control and self-efficacy in physical activity. The design was a randomized controlled trial with a questionnaire before and after the intervention. At post-intervention, there were significant increases in scores of internal health locus of control and self-efficacy in the experimental group (n = 109) compared to the control group (n = 101). It was concluded that a short-term health education may empower women to adopt healthy lifestyles.

Phase II trial of old age acute myeloid leukemia treatment by arsenic trioxide and low-dose subcutaneous cytosin arabinoside

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Background: AML is a disease of old age, but unfortunately due to several factors standard treatment can not be delivered to these patients. Here we tried to achieve to bet possible response to these patients. Methods: Eleven old age patients selected for this trial. Patients couldn't tolerate standard treatment of AML due to old age or comorbid disorders. Treatment consist of best supportive care plus administration of low dose ARA-C (20mg/day as SQ) for 10 days each months and arsenic trioxide 10 mg/day as 2 hour iv infusion each month. Patients followed by CBC and BMA/B when peripheral blood normalized or every other month. Results: This cohort consist of 8 men and 3 women. Median age was 75 y/o (55–80). Median WBC count Hb level and platelet count at presentation were 42,860μl, 8.3g/dl and 30,500/μl, respectively. Complete remission observed in 6 and partial remission in one patient (RR = 63.6%), but remission was short live, after 6 months one patient was in CR and one in PR. After 12 months, only one patient was in PR. Median survival was 6 months and 6 patients survive more than 6 months. Two patients are alive after 12 months. Conclusions: Although prognosis of old age AML remain poor, but with this type of treatment RR is acceptable. In this very high-risk group of very old AML, combination of ATO and ARA-C possibly could improve survival.

No significant financial relationships to disclose.

Nosocomial blood stream infections in Imam Khomeini Hospital, Urmia, Islamic Republic of Iran, 1999-2001

In a 2-year retrospective study, the database of the microbiology laboratory of the Imam Khomeini Hospital was reviewed to identify patients who had nosocomial bacteraemia between 1 May 1999 and 31 May 2001 and identify the pathogen responsible and its resisitance to antibiotics. Of 6492 patients in various wards, 593 (9.1%) had positive blood cultures; 85 of those (14.3%) had signs of potential skin contamination. Gram-positive cocci, including coagulase-negative staphylococci, Staphylococcus aureus, Streptococcus pneumoniae and other Gram-positive cocci, accounted for 42.3% of isolates. Gram-negative bacilli were responsible for another 42.3% of isolates; Pseudomonas aeruginosa was the predominant isolate. Patterns of drug resistance varied according to species of bacteria but were generally quite high.