Association between rs4673 (C/T) and rs13306294 (A/G) haplotypes of NAD(P)H oxidase p22phox gene and severity of stenosis in coronary arteries

Phagocytic NADH/NADPH oxidase is an important enzyme producing reactive oxygen species within subendothelial space of vessels. Findings have shown that p22phox subunit is an essential element related to the enzyme activity. Since some p22phox polymorphisms are thought to have functional roles in the enzyme thus, we studied the association between rs4673 (C242T) and rs13306294 (A/G) haplotypes and the severity of stenosis in coronary arteries. One hundred eighty-two subjects undergoing coronary angiography were recruited on the base of study design. Patients (n=114) had at least a stenosed coronary artery (>50% stenosis) and subdivided into three subgroups; SVD (n=28), 2VD (n=31) and 3VD (n=55) while controls (n=68) had the normal coronary arteries (<5% stenosis). The direct haplotyping technique of SNPs was performed using ARMS-RFLP-PCR method. Furthermore, alphabet-based tools predicted the changes of secondary structure at the rs4673 position. All haplotypes being proposed theoretically were found in the study population. The distribution of two-allele haplotypes had no significant difference between patients and controls (P=0.1). Although the rs4673 allele frequency was not significant between the groups (P>0.5), chi square test and multinomial regression analysis showed an observed high risk for rs13306294 A allele among patients. The bioinformatics tools predicted that the p22phox secondary structure is not changed due to the substitution of Tyr→His at the rs4673 position. We concluded that the polymorphisms have no allele linkage on the chromosome. In addition, the rs13306294 A allele is a potential factor of stenosis of coronary arteries that increases susceptibility for the extent of disease.     

Inhibition of NADPH oxidase alleviates germ cell apoptosis and ER stress during testicular ischemia reperfusion injury

Testicular torsion and detorsion (TTD) is a serious urological condition affecting young males that is underlined by an ischemia reperfusion injury (tIRI) to the testis as the pathophysiological mechanism. During tIRI, uncontrolled production of oxygen reactive species (ROS) causes DNA damage leading to germ cell apoptosis (GCA). The aim of the study is to explore whether inhibition of NADPH oxidase (NOX), a major source of intracellular ROS, will prevent tIRI-induced GCA and its association with endoplasmic reticulum (ER) stress. Sprague-Dawley rats (n = 36) were divided into three groups: sham, tIRI only and tIRI treated with apocynin (a NOX inhibitor). Rats undergoing tIRI endured an ischemic injury for 1 h followed by 4 h of reperfusion. Spermatogenic damage was evaluated histologically, while cellular damages were assessed using real time PCR, immunofluorescence staining, Western blot and biochemical assays. Disrupted spermatogenesis was associated with increased lipid and protein peroxidation and decreased antioxidant activity of the enzyme superoxide dismutase (SOD) as a result of tIRI. In addition, increased DNA double strand breaks and formation of 8-OHdG adducts associated with increased phosphorylation of the DNA damage response (DDR) protein H2AX. The ASK1/JNK apoptosis signaling pathway was also activated in response to tIRI. Finally, increased immuno-expression of the unfolded protein response (UPR) downstream targets: GRP78, eIF2-α1, CHOP and caspase 12 supported the presence of ER stress. Inhibition of NOX by apocynin protected against tIRI-induced GCA and ER stress. In conclusion, NOX inhibition minimized tIRI-induced intracellular oxidative damages leading to GCA and ER stress.     

Functions and dysfunctions of nitric oxide in brain

Nitric oxide (NO) works as a retrograde neurotransmitter in synapses, allows the brain blood flow and also has important roles in intracellular signaling in neurons from the regulation of the neuronal metabolic status to the dendritic spine growth. Moreover NO is able to perform post-translational modifications in proteins by the S-nitrosylation of the thiol amino acids, which is a physiological mechanism to regulate protein function. On the other hand, during aging and pathological processes the behavior of NO can turn harmful when reacts with superoxide anion to form peroxynitrite. This gaseous compound can diffuse easily throughout the neuronal membranes damaging lipid, proteins and nucleic acids. In the case of proteins, peroxynitrite reacts mostly with the phenolic ring of the tyrosines forming nitro-tyrosines that affects dramatically to the physiological functions of the proteins. Protein nitrotyrosination is an irreversible process that also yields to the accumulation of the modified proteins contributing to the onset and progression of neurodegenerative processes such as Alzheimer's disease or Parkinson's disease.