Mitochondrial 4977-bp Deletion Research Articles

Analysis of Mitochondrial 4977-bp Deletion and D-Loop Variation in Iranian Non-Alcoholic Fatty Liver Disease Patients

Background: Accumulating evidence indicates that mitochondrial dysfunction is considered an effective factor in the formation or development of non-alcoholic fatty liver disease (NAFLD) although the underlying mechanisms of the changes are still unclear. Objectives: The aim of the study was to determine the 4977-bp deletion levels and variations in the displacement (D) loop region of mitochondrial DNA (mtDNA) in NAFLD patients. Methods: In this case-control study, 43 NAFLD patients and 156 controls were enrolled. The blood DNA of 43 patients with NAFLD and 156 healthy individuals was investigated to determine the 4977-bp deletion and sequence changes in the D-loop region using methods such as polymerase chain reaction (PCR), multiplex PCR, and DNA sequencing. Results: The results indicated that no 4977-bp deletion was found in any of the samples. 94 variations were found in the D-loop region including two deletions, four insertions, and 88 single nucleotide polymorphisms (SNP), 16 of which were just found in patients. There was a significant difference between the NAFLD patients and controls in six variants (P 0.05) in C variations in D310 mitochondrial DNA between the two groups. Conclusions: According to the findings, we believe that the disease damages the mitochondrial DNA and leads to the formation of these mutations. Our results also showed that D-loop alterations are frequent in NAFLD and may play a significant role in the progression of NAFLD.

Molecular damage and responses of oral keratinocyte to hydrogen peroxide

BackgroundHydrogen peroxide (H2O2)-based tooth bleaching reagents have recently increased in popularity and controversy. H2O2 gel (3%) is used in a Nightguard for vital bleaching; transient tooth sensitivity and oral mucosa irritation have been reported. Genotoxicity and carcinogenicity have also been significant concerns.MethodsWe used primary cultured normal human oral keratinocytes (NHOKs) as an in vitro model to investigate the pathological effects to mitochondria functions on human oral keratinocytes exposed to different doses of H2O2 for different durations.ResultsAn MTT assay showed compromised cell viability at a dose over 5 mM. The treatments induced nuclear DNA damage, measured using a single-cell gel electrophoresis assay. A real-time quantitative polymerase chain reaction showed H2O2 induced significant increase in mitochondrial 4977-bp deletion. Mitochondrial membrane potential and apoptosis assays suggested that oxidative damage defense mechanisms were activated after prolonged exposure to H2O2. Reduced intracellular glutathione was an effective defense against oxidative damage from 5 mM of H2O2.ConclusionOur study suggests the importance for keratinocyte damage of the dose and the duration of the exposure to H2O2 in at-home-bleaching. A treatment dose ≥100 mM directly causes severe cytotoxicity with as little as 15 min of exposure.

Mitochondrial Common Deletion Level in Blood: New Insight Into the Effects of Age and Body Mass Index.

Background: Age-related decrease in mitochondrial activity has been reported in several tissues. Reactive Oxygen Species (ROS) produced from defected mitochondria lead to aging and accumulate through time. However, studies about the mitochondrial DNA mutation level in blood are contradictory. Other lifestyle factors may modify the effects of age in post-mitotic tissues such as blood. The BMI represents the sum of the various lifestyle factors.Objective: We proposed that age, obesity and mtDNA deletion are three ROS producing factors, which may interact with each other and induce senescence.Methods: In a cross-sectional study, 172 male and female volunteers without known mitochondrial diseases were selected and the presence of common mitochondrial 4977bp deletion (ΔmtDNA4977) evaluated using Nested-PCR.Results: Our results showed that a high percentage of samples (54.06%) harbor common deletion in blood. Furthermore, both BMI and the ΔmtDNA4977 levels significantly decrease with age. The chronological age, BMI and ΔmtDNA4977 reciprocally affect each other.Conclusion: Our data suggest that age affects purifying selection and BMI, which may influence the relative level of the mtDNA common deletion in blood.

Detection of 4977-bp deletion of mitochondrial DNA in in vitro fertilization failure women: A case-control study

The quality of oocyte is often considered as a limiting factor for fertility, especially IVF. Some mitochondrial mutations, particularly the 4977-bp deletion increase with the age. Thus, this mutation can serve as a marker for cell aging, which indicates the reduced quality of the oocytes for fertilization. It has been suggested that this can also be investigated in the blood cells of women with IVF failure. 1-Determination of the frequency of 4977-bp deletion in women with IVF failure, 2-Investigation of the relationship between 4977-bp deletion and the age of patients. Polymerase chain reaction was used to detect the 4977-bp deletion in blood samples of 52 IVF failure women and 52 women who had at least one healthy child. After polymerase chain reaction with deleted and wild-type primers, the products were examined using agarose gel electrophoresis. 48.07% of women with IVF failure and 34.62% of healthy women had a mitochondrial 4977-bp deletion, with p=0.163 and OR: 1.749. Also, in association with the age of these patients and the frequency of 4977-bp mutation, p and OR were obtained 0.163 and 1.749, respectively and frequency of this mutation was higher in patients over 35 yr old compared to other subgroups (Patients ≥35: 57.69). According to the findings of this study, there is no a significant relationship between the frequency of mitochondrial 4977-bp mutation and failure in IVF.

P6200Increased mitochondrial 4977-bp deletion and copy number in cath lab personnel with long-term occupational exposure to ionizing radiation

P6200Increased mitochondrial 4977-bp deletion and copy number in cath lab personnel with long-term occupational exposure to ionizing radiation

Tracking of the genetic deafness associated to the aging in Brazilian patients

Introduction Presbyacusis is the most common cause of auditory dysfunction that is generally associated with aging in industrialized societies. Objective To assess the presence of the mitochondrial 4977-bp deletion in Brazilian patients with presbyacusis. Materials and methods One hundred unrelated patients of both genders were clinically examined to exclude syndromic forms of deafness. Specific oligonucleotide primers were designed to amplify the cytochrome b gene and the 4977-bp deletion of the mtDNA using the polymerase chain reaction. Results The mtDNA 4977 deletion was not identified in any of the samples analyzed. A region of the cytochrome b gene has been previously amplified and the presence of the mtDNA and the non-deleted mtDNA was confirmed in all of the samples. Conclusions These molecular findings disagree with reports describing the mtDNA 4977 deletion associated with aging, but do not discard the possibility of the existence of mutations in other genes in the patients and, highlight the importance of identifying the underlying genetic causes of presbyacusis, in the Brazilian population, to provide a better understanding of the internal ear diseases.

Methodical approach to brain hypoxia/ischemia as a fundamental problem in forensic neuropathology

A review is given summarizing different methods that have been applied to the specific forensic neuropathological question of brain hypoxia/ischemia. On the microscopic level the authors applied routine stains and immunohistochemistry (MAP2, ALZ 50, GFAP, CD68, β-APP) for characterization of the functional activity of neurons as well as of different cell types in various brain areas. Moreover, using molecular techniques for evaluation of the mitochondrial 4977-bp deletion in correlation to hypoxia and to age brain tissue and single cell analyses are described. The demonstrated scope of methods and results give evidence of the wide spectrum of possibilities to visualize hypoxic brain injuries for determining the cause (and matter) of death and for reconstructing the time-dependent process.

The prevalence of mtDNA4977 deletion in primary human endometrial carcinomas and matched control samples

mtDNA4977, the most common deletion of the mitochondrial DNA, has been detected in different types of human neoplasia. The aim of the current study was to determine the prevalence of mtDNA4977 deletion in primary human endometrial carcinomas (EC) as compared with matched control samples. Thirty-seven matched control tissues and EC samples were enrolled, and the 4977-bp mtDNA deletion was investigated using a PCR-based technique. Deletion of mtDNA4977 was detected in 32 out of 37 (84%) matched control samples and in 30 out of 37 (81%) ECs. A statistically significant correlation of mtDNA4977/wild-type mtDNA ratios was noted between normal and cancerous human endometrial tissues (R=0.844, p<0.0001). The intensity ratio of mtDNA bands was significantly higher in normal samples than in malignant human endometrial tissues (p=0.021). The mean mtDNA4977/wild-type mtDNA ratio was significantly higher in the control group (0.655+/-0.379) than in the cancer group (0.570+/-0.04, p=0.048) of patients between 50 and 60 years of age. Notably, there was a relationship between clinical stage of the disease (stage II versus III) and the amount of mtDNA4977 in ECs (p=0.048). The sequence analysis of two randomly selected EC-positive cases confirmed that amplified fragments originated from mtDNA, and both encompassed deletion. In conclusion, we suggest that mitochondrial 4977-bp deletion is not specific to EC tissues. The accumulation of mtDNA4977 may be associated with aging processes, particularly in peri-menopausal women affected by EC.