A high number of 'natural' mitochondrial DNA polymorphisms in a symptomatic Brugada syndrome type 1 patient.

Brugada syndrome (BrS) is a rare genetic arrhythmic disorder with a complex model of transmission. At least 20 different genes have been identified as BrS-causal or susceptibility genes. Of these, SCN5A is the most frequently mutated. Coregulation of different mutations or genetic variants, including mitochondrial DNA (mtDNA), may contribute to the clinical phenotype of the disease. In thepresent study, we analysed the mitochondrial genome of a symptomatic BrS type 1 patient to investigate a possible mitochondrial involvement recently found in the arrhytmogenic diseases. No pathogenic mutation was identified; however, a high number of singlenucleotide polymorphisms were found (n=21) and some of them were already been reported in molecular autopsy case for sudden death.The results reported here further support our hypothesis on the potential role of mtDNA polymorphisms in mitochondrial dysfunction, which may represent a risk factor for arrhythmogenic disease.

Can Tangier disease cause male infertility? A case report and an overview on genetic causes of male infertility and hormonal axis involved.

Tangier disease is an autosomal recessive disorder caused by mutations in the ABCA1 gene and characterized by the accumulation of cholesteryl ester in various tissues and a near absence of high-density lipoprotein. The subject in this investigation was a 36-year-old Italian man with Tangier disease. He and his wife had come to the In Vitro Fertilization Unit, Pesaro Hospital (Azienda Ospedaliera Ospedali Riuniti Marche Nord) seeking help regarding fertility issues. The man was diagnosed with severe oligoasthenoteratozoospermia. Testosterone is the sex hormone necessary for spermatogenesis and cholesterol is its precursor; hence, we hypothesized that the characteristic cholesterol deficiency in Tangier disease patients could compromise their fertility. The aim of the study was to therefore to determine if there is an association between Tangier disease and male infertility. After excluding viral, infectious, genetic and anatomical causes of the subject's oligoasthenoteratozoospermia, we performed a hormonal analysis to verify our hypothesis. The patient was found to be negative for frequent bacteria and viruses. The subject showed a normal male karyotype and tested negative for Yq microdeletions and Cystic Fibrosis Transmembrane Conductance Regulator gene mutations. A complete urological examination was performed, and primary hypogonadism was also excluded. Conversely, hormonal analyses showed that the subject had a high level of follicle stimulating hormone and luteinizing hormone, low total testosterone and a significant decline in inhibin B. We believe that the abnormally low cholesterol levels typically found in subjects with Tangier disease may result in a reduced testosterone production which in turn could affect the hormonal axis responsible for spermatogenesis leading to a defective maturation of spermatozoa.

Mutational analysis of mitochondrial DNA in Brugada syndrome.

BACKGROUND: Brugada syndrome (BrS) is a primary electrical disease associated with an increased risk of sudden cardiac death due to ventricular fibrillation. This pathology has nuclear heterogeneous genetic origins, and at present, molecular diagnostic tests on nuclear DNA cover only 30% of BrS patients. The aim of this study was to assess the possible involvement of mitochondrial (mt) DNA variants in BrS since their etiological role in several cardiomyopathies has already been described. METHODS AND RESULTS: The whole mt genome of BrS patients was sequenced and analyzed. A specific mtDNA mutation responsible for BrS can be excluded, but BrS patient d-loop was found to be more polymorphic than that of control cases (P=0.003). Moreover, there appears to be an association between patients with the highest number of variants (n>20) and four mt Single Nucleotide Polymorphism (SNPs) (T4216C, A11251G, C15452A, T16126C) and the most severe BrS phenotype (P=0.002). CONCLUSIONS: The high substitution rate found in BrS patient mtDNA is unlikely to be the primary cause of the disease, but it could represent an important cofactor in the manifestation of the BrS phenotype. Evidence suggesting that a specific mtDNA allelic combination and a high number of mtDNA SNPs may be associated with more severe cases of BrS represents the starting point for further cohort studies aiming to test whether this mt genetic condition could be a genetic modulator of the BrS clinical phenotype.

Comparative analysis between saliva and buccal swabs as source of DNA: lesson from HLA-B*57:01 testing.

AIM: Our work aimed to designate the optimal DNA source for pharmacogenetic assays, such as the screening for HLA-B*57:01 allele. MATERIALS & METHODS: A saliva and four buccal swab samples were taken from 104 patients. All the samples were stored at different time and temperature conditions and then genotyped for the HLA-B*57:01 allele by SSP-PCR and classical/capillary electrophoresis. RESULTS: The genotyping analysis reported different performance rates depending on the storage conditions of the samples. Given our results, the buccal swab demonstrated to be more resistant and stable in time with respect to the saliva. CONCLUSION: Our investigation designates the buccal swab as the optimal DNA source for pharmacogenetic assays in terms of resistance, low infectivity, low-invasiveness and easy sampling, and safe transport in centralized medical centers providing specialized pharmacogenetic tests.

The pleiotropic effect of physical exercise on mitochondrial dynamics in aging skeletal muscle.

Decline in human muscle mass and strength (sarcopenia) is one of the principal hallmarks of the aging process. Regular physical exercise and training programs are certain powerful stimuli to attenuate the physiological skeletal muscle alterations occurring during aging and contribute to promote health and well-being. Although the series of events that led to these muscle adaptations are poorly understood, the mechanisms that regulate these processes involve the "quality" of skeletal muscle mitochondria. Aerobic/endurance exercise helps to maintain and improve cardiovascular fitness and respiratory function, whereas strength/resistance-exercise programs increase muscle strength, power development, and function. Due to the different effect of both exercises in improving mitochondrial content and quality, in terms of biogenesis, dynamics, turnover, and genotype, combined physical activity programs should be individually prescribed to maximize the antiaging effects of exercise.

The Pharmacogenomic HLA Biomarker Associated to Adverse Abacavir Reactions: Comparative Analysis of Different Genotyping Methods.

Many pharmacogenomic biomarkers (PGBM) were identified and translated into clinical practice, affecting the usage of drugs via label updates. In this context, abacavir is one of the most brilliant examples of pharmacogenetic studies translated into clinical practice. Pharmacogenetic studies have revealed that abacavir HSRs are highly associated with the major histocompatibility complex class I. Large studies established the effectiveness of prospective HLA-B*57:01 screening to prevent HSRs to abacavir. Accordingly to these results the abacavir label has been modified: the European Medicines Agency (EMA) and the FDA recommend/suggested that the administration of abacavir must be preceded by a specific genotyping test. The HLA locus is extremely polymorphic, exhibiting many closely related alleles, making it difficult to discriminate HLA-B*57:01 from other related alleles, and a number of different molecular techniques have been developed recently to detect the presence of HLA-B*57:01. In this review, we provide a summary of the available techniques used by laboratories to genotype HLA-B*57:01, outlining the scientific and pharmacoeconomics pros and cons.

Morphofunctional and Biochemical Approaches for Studying Mitochondrial Changes during Myoblasts Differentiation.

This study describes mitochondrial behaviour during the C2C12 myoblast differentiation program and proposes a proteomic approach to mitochondria integrated with classical morphofunctional and biochemical analyses. Mitochondrial ultrastructure variations were determined by transmission electron microscopy; mitochondrial mass and membrane potential were analysed by Mitotracker Green and JC-1 stains and by epifluorescence microscope. Expression of PGC1α, NRF1α, and Tfam genes controlling mitochondrial biogenesis was studied by real-time PCR. The mitochondrial functionality was tested by cytochrome c oxidase activity and COXII expression. Mitochondrial proteomic profile was also performed. These assays showed that mitochondrial biogenesis and activity significantly increase in differentiating myotubes. The proteomic profile identifies 32 differentially expressed proteins, mostly involved in oxidative metabolism, typical of myotubes formation. Other notable proteins, such as superoxide dismutase (MnSOD), a cell protection molecule, and voltage-dependent anion-selective channel protein (VDAC1) involved in the mitochondria-mediated apoptosis, were found to be regulated by the myogenic process. The integration of these approaches represents a helpful tool for studying mitochondrial dynamics, biogenesis, and functionality in comparative surveys on mitochondrial pathogenic or senescent satellite cells.

A fluorescence-based sequence-specific primer PCR for the screening of HLA-B(*)57:01.

Abacavir (ABC) is an antiretroviral drug highly effective in the treatment of HIV, but its intake can cause severe hypersensitivity reaction (HSR). A strong association between HLA-B(*)57:01 and ABC HSRs was reported by several studies, which demonstrated that HLA-B(*)57:01 screening had a 100% negative predictive value and that it could accurately identify patients at high risk of ABC HSRs. We propose a new sequence-specific primer PCR assay based on fluorescence detection through CE which is highly sensitive, allowing the use of non-infective sources of DNA such as saliva and buccal swabs, in addition to blood and reproducible, allowing automation of the analytical process. The results of our study were first compared with a standard sequence-specific primer PCR technique and reported a concordance of 100%, and then a blind external validation further confirmed the accuracy of our method.

Effects of a 300 mT static magnetic field on human umbilical vein endothelial cells.

This study describes the effects of a static magnetic field (SMF) on cell growth and DNA integrity of human umbilical vein endothelial cells (HUVECs). Fast halo assay was used to investigate nuclear damage; quantitative polymerase chain reaction (QPCR), standard PCR, and real-time PCR were used to evaluate mitochondrial DNA integrity, content, and gene expression. HUVECs were continually exposed to a 300 mT SMF for 4, 24, 48, and 72 h. Compared to control samples (unexposed cultures) the SMF-exposed cells did not show a statistically significant change in their viability. Conversely, the static field was shown to be significant after 4 h of exposure, inducing damage on both the nuclear and mitochondrial levels, reducing mitochondrial content and increasing reactive oxygen species. Twenty-four hours of exposure increased mitochondrial DNA content as well as expression of one of the main genes related to mitochondrial biogenesis. No significant differences between exposed and sham cultures were found after 48 and 72 h of exposure. The results suggest that a 300 mT SMF does not cause permanent DNA damage in HUVECs and stimulates a transient mitochondrial biogenesis.

A new real-time PCR method to overcome significant quantitative inaccuracy due to slight amplification inhibition.

BACKGROUND: Real-time PCR analysis is a sensitive DNA quantification technique that has recently gained considerable attention in biotechnology, microbiology and molecular diagnostics. Although, the cycle-threshold (Ct) method is the present "gold standard", it is far from being a standard assay. Uniform reaction efficiency among samples is the most important assumption of this method. Nevertheless, some authors have reported that it may not be correct and a slight PCR efficiency decrease of about 4% could result in an error of up to 400% using the Ct method. This reaction efficiency decrease may be caused by inhibiting agents used during nucleic acid extraction or copurified from the biological sample. We propose a new method (Cy0) that does not require the assumption of equal reaction efficiency between unknowns and standard curve. RESULTS: The Cy0 method is based on the fit of Richards' equation to real-time PCR data by nonlinear regression in order to obtain the best fit estimators of reaction parameters. Subsequently, these parameters were used to calculate the Cy0 value that minimizes the dependence of its value on PCR kinetic. The Ct, second derivative (Cp), sigmoidal curve fitting method (SCF) and Cy0 methods were compared using two criteria: precision and accuracy. Our results demonstrated that, in optimal amplification conditions, these four methods are equally precise and accurate. However, when PCR efficiency was slightly decreased, diluting amplification mix quantity or adding a biological inhibitor such as IgG, the SCF, Ct and Cp methods were markedly impaired while the Cy0 method gave significantly more accurate and precise results. CONCLUSION: Our results demonstrate that Cy0 represents a significant improvement over the standard methods for obtaining a reliable and precise nucleic acid quantification even in sub-optimal amplification conditions overcoming the underestimation caused by the presence of some PCR inhibitors.

Differential effect of creatine on oxidatively-injured mitochondrial and nuclear DNA.

Creatine is a naturally occurring compound obtained in humans from endogenous production and consumption through the diet. It is used as an ergogenic aid to improve exercise performance and increase fat-free mass. Lately, creatine's positive therapeutic benefits in various oxidative stress-associated diseases have been reported in literature and, more recently, creatine has also been shown to exert direct antioxidant effects. Oxidatively-challenged DNA was analysed to show possible protective effects of creatine. Acellular and cellular studies were carried out. Acellular assays, performed using molecular approaches, showed that creatine protects circular and linear DNA from oxidative attacks. Nuclear and mitochondrial DNAs from oxidatively-injured human umbilical vein endothelial cells were analyzed. Creatine supplementation showed significant genoprotective activity on mitochondrial DNA. This evidence suggests that creatine may play an important role in mitochondrial genome stability in that it could normalize mitochondrial mutagenesis and its functional consequences. Thus, creatine supplementation could be used to prevent or ameliorate diseases related to mitochondrial DNA mutations, and possibly to delay aging.

Fine needle aspiration coupled with real-time PCR: a painless methodology to study adaptive functional changes in skeletal muscle.

BACKGROUND AND AIM: In this study we developed a new methodology for obtaining human skeletal muscle samples to evaluate gene expression. This approach is based on a fine needle aspiration technique, which allows us to extract a small tissue sample in a significantly less invasive manner than with classic biopsy. METHODS AND RESULTS: Multiplex tandem RT-PCR was used to determine the mRNA levels of genes involved in ATP production and mitochondrial biogenesis in muscle tissue. Samples of vastus lateralis muscle were obtained from 21 healthy subjects with different fitness levels. The principal findings in our study show a strong correlation between PGC-1alpha and COX5B (p<0.001) and between PGC-1alpha and MT-CO2 (p=0.017) expression. Furthermore, a significant positive correlation between mtDNA content and the percentage of MHCI present in the aspired samples were found (p=0.028). These data are in agreement with current knowledge on skeletal muscle physiology and show the reliability of the proposed method. CONCLUSION: This painless methodology can be used to investigate, in vivo, human muscle RNA and DNA adaptations in response to either physiological and/or pharmacological stimuli. This method has major clinical relevance, such as its application in clarifying the mechanisms underling metabolic and systemic disorders.