Suppression of high pacing-induced ANP secretion by antioxidants in isolated rat atria

Reactive oxygen species (ROS) are formed as a natural by-product of the normal metabolism of oxygen and have important roles in cell signaling. The aim of this study was to investigate direct effects of ROS on atrial hemodynamics and ANP secretion in isolated perfused beating rat atria with antioxidants. When atria were paced at 1.2 Hz, N-acetyl cystein (antioxidant, NAC), α-lipoic acid (antioxidant), tempol (superoxide dismutase mimic), and apocynin (NADPH oxidase inhibitor; NOX inhibitor) did not affect ANP secretion and atrial contractility. When pacing frequency was increased from 1.2 Hz to 4 Hz, the ANP secretion increased and atrial contractility decreased. H₂O₂ level was increased in perfusate obtained from atria stimulated by high pacing frequency. NAC, α-lipoic acid and tempol attenuated high pacing frequency-induced ANP secretion but apocynin did not. In contrast, pyrogallol (a superoxide generator) augmented high pacing frequency-induced ANP secretion. NOX-4 protein was increased by high pacing stimulation and in diabetic rat atria. In diabetic rat atria, high pacing frequency caused an increased ANP secretion and a decreased atrial contractility, that were markedly attenuated as compared to control rats. NAC and apocynin reduced high pacing frequency-induced ANP secretion in diabetic rat atria. These results suggest that intracellular ROS formation partly through an increasing NOX activity in response to high pacing frequency is associated with an increased ANP secretion in rat atria.     

RETRACTED ARTICLE: Serum Zinc and Adiponectin Levels in Patients with Polycystic Ovary Syndrome,Adjusted for Anthropometric,Biochemical, Dietary Intake,and Physical Activity Measures

Biological Trace Element Research -     

Characterization of a bacteriocin-producing strain of Enterococcus faecalis from cow’s milk used in the production of Moroccan traditional dairy foods

A bacteriocin-producing lactic acid bacterium (strain 2.5) isolated from cow’s milk used in cheese production from Northern Morocco was selected for its strong anti-listerial activity. The producer strain was identified as Enterococcus faecalis by molecular methods. Strain 2.5 carried the genetic determinants for the two-peptide enterococcal bacteriocin enterocin 1071, and the active bacteriocin was purified to homogeneity by reversed-phase chromatography from culture broths of the producer strain. Strain 2.5 carried two plasmids (of ∼7 and 40 kb). Characterization of strain 2.5 at biosafety level indicated that this strain is non-haemolytic, and lacks the genetic determinants for most of the virulence factors described in enterococci (cylB, cylM, gelE, ace and agg) although it carried the genetic determinants cylA, efaAfs as well as determinants for the sex pheromone peptides cpd, cob, and ccf. Strain 2.5 was resistant to tetracycline, rifampicin, and ciprofloxacin, but it was sensitive to penicillin, ampicillin, vancomycin, and teicoplanin. Results from the present study support the potential role of strain 2.5 as an anti-listerial agent to be tested in traditional fermented foods.     

Novel strategies for inhibition of bacterial biofilm in chronic rhinosinusitis

An important role has been recently reported for bacterial biofilm in the pathophysiology of chronic diseases, such as chronic rhinosinusitis (CRS). CRS, affecting sinonasal mucosa, is a persistent inflammatory condition with a high prevalence around the world. Although the exact pathological mechanism of this disease has not been elicited yet, biofilm formation is known to lead to a more significant symptom burden and major objective clinical indicators. The high prevalence of multidrug-resistant bacteria has severely restricted the application of antibiotics in recent years. Furthermore, systemic antibiotic therapy, on top of its insufficient concentration to eradicate bacteria in the sinonasal biofilm, often causes toxicity, antibiotic resistance, and an effect on the natural microbiota, in patients. Thus, coming up with alternative therapeutic options instead of systemic antibiotic therapy is emphasized in the treatment of bacterial biofilm in CRS patients. The use of topical antibiotic therapy and antibiotic eluting sinus stents that induce higher antibiotic concentration, and decrease side effects could be helpful. Besides, recent research recognized that various natural products, nitric oxide, and bacteriophage therapy, in addition to the hindered biofilm formation, could degrade the established bacterial biofilm. However, despite these improvements, new antibacterial agents and CRS biofilm interactions are complicated and need extensive research. Finally, most studies were performed in vitro, and more preclinical animal models and human studies are required to confirm the collected data. The present review is specifically discussing potential therapeutic strategies for the treatment of bacterial biofilm in CRS patients.     

Distribution of epithelial sodium channels and mineralocorticoid receptors in cardiovascular regulatory centers in rat brain

Epithelial sodium channels (ENaC) are important for regulating sodium transport across epithelia. Functional studies indicate that neural mechanisms acting through mineralocorticoid receptors (MR) and sodium channels (presumably ENaC) are crucial to the development of sympathoexcitation and hypertension in experimental models of salt-sensitive hypertension. However, expression and localization of the ENaC in cardiovascular regulatory centers of the brain have not yet been studied. RT-PCR and immunohistochemistry were performed to study ENaC and MR expression at the mRNA and protein levels, respectively. Both mRNA and protein for alpha-, beta-, and gamma-ENaC subunits and MR were found to be expressed in the rat brain. All three ENaC subunits and MR were present in the supraoptic nucleus, magnocellular paraventricular nucleus, hippocampus, choroid plexus, ependyma, and brain blood vessels, suggesting the presence of multimeric channels and possible regulation by mineralocorticoids. In most cortical areas, thalamus, amygdala, and suprachiasmatic nucleus, notable expression of gamma-ENaC was undetectable, whereas alpha- and beta-ENaC were abundantly expressed pointing to the possibility of a heterogeneous population of channels. The findings suggest that stoichiometrically different populations of ENaC may be present in both epithelial and neural components in the brain, which may contribute to regulation of cerebrospinal fluid and interstitial Na+ concentration as well as neuronal excitation.     

HER2+ mCRC patients with exon 20 R784G substitution mutation do not respond to the cetuximab therapy

The human epidermal growth factor 2 (HER2) gene undergoes various mutations that could alter its activity or respond to the antibody therapies. Cetuximab, a known anti-EGFR monoclonal antibody (mAB), is widely administered in metastatic colorectal cancer (mCRC) cases. Here we identified mCRC patients who did not respond to cetuximab (500 mg/m², q2w) after fluoropyrimidine/oxaliplatin regimen failure. Tumor samples were examined with immunohistochemistry for protein distribution, polymerase chain reaction (PCR) sequencing for mutation detection and real-time PCR for mRNA expression pattern analysis between cetuximab sensitive and resistance patients. The conformational differences of normal and mutated protein structures were predicted by bioinformatics analysis. The 5-year survival rates of target groups were estimated using the Kaplan–Meier method. Immunohistochemistry showed that all cases had high level of HER2 protein. No K-Ras or B-Raf mutation was observed among the study population; however, cetuximab resistance patients harbored a somatic mutation R784G at the exon 20 region of HER2 coding sequence. According to bioinformatics analysis, this mutation caused a notable misfold in protein conformation. Meanwhile, survival analysis showed R784G mutated mCRC patients had shortened survival rate compared with the mCRC cases with wild-type HER2. Collectively, these data report a new mechanism of resistance to cetuximab and might be applicable in modifying new therapeutic strategies for HER2 involved cancers.     

Effect of single nucleotide polymorphisms in SEPS1 and SEPP1 on expression in the protein level in metabolic syndrome in subjects with cardiovascular disease

Molecular Biology Reports - Metabolic syndrome (MetS) results from the interaction between environmental and genetic factors. Several previous studies considered the role of selenium in developing...     

Engineering,Cloning and Expression of Interleukin 2–Com1 Chimera with Aim of Recombinant Subunit Vaccine Production Against Coxiella burnetii

International Journal of Peptide Research and Therapeutics - Query fever is an important disease caused by Coxiella burnetii, therefore vaccination against this disease is so crucial. Com1 is one...