Role of c-miR-21, c-miR-126, Redox Status, and Inflammatory Conditions as Potential Predictors of Vascular Damage in T2DM Patients.

The development of type 2 diabetes mellitus (T2DM) vascular complications (VCs) is associated with oxidative stress and chronic inflammation and can result in endothelial dysfunctions. Circulating microRNAs play an important role in epigenetic regulation of the etiology of T2DM. We studied 30 healthy volunteers, 26 T2DM patients with no complications, and 26 T2DM patients with VCs, to look for new biomarkers indicating a risk of developing VCs in T2DM patients. Peripheral blood samples were used to determine redox state, by measuring the endogenous antioxidant defense system (superoxide dismutase, SOD; catalase, CAT; glutathione reductase, GRd; glutathione peroxidase, GPx; and glucose-6-phosphate dehydrogenase, G6DP) and markers of oxidative damage (advanced oxidation protein products, AOPP; lipid peroxidation, LPO). Additionally, inflammatory marker levels (IL-1, IL-6, IL-18, and TNF-α), c-miR-21, and c-miR-126 expression were analyzed. T2DM patients showed the highest oxidative damage with increased GSSG/GSH ratios, LPO, and AOPP levels. In both diabetic groups, we found that diminished SOD activity was accompanied by increased CAT and decreased GRd and G6PD activities. Diabetic patients presented with increased relative expression of c-miR-21 and decreased relative expression of c-miR-126. Overall, c-miR-21, SOD, CAT, and IL-6 had high predictive values for diabetes diagnoses. Finally, our data demonstrated that IL-6 exhibited predictive value for VC development in the studied population. Moreover, c-miR-21 and c-miR-126, along with GPx and AOPP levels, should be considered possible markers for VC development in future studies.

Melatonin enhances neural stem cell differentiation and engraftment by increasing mitochondrial function.

Neural stem cells (NSCs) are regarded as a promising therapeutic approach to protecting and restoring damaged neurons in neurodegenerative diseases (NDs) such as Parkinson's disease and Alzheimer's disease (PD and AD, respectively). However, new research suggests that NSC differentiation is required to make this strategy effective. Several studies have demonstrated that melatonin increases mature neuronal markers, which reflects NSC differentiation into neurons. Nevertheless, the possible involvement of mitochondria in the effects of melatonin during NSC differentiation has not yet been fully established. We therefore tested the impact of melatonin on NSC proliferation and differentiation in an attempt to determine whether these actions depend on modulating mitochondrial activity. We measured proliferation and differentiation markers, mitochondrial structural and functional parameters as well as oxidative stress indicators and also evaluated cell transplant engraftment. This enabled us to show that melatonin (25 µM) induces NSC differentiation into oligodendrocytes and neurons. These effects depend on increased mitochondrial mass/DNA/complexes, mitochondrial respiration, and membrane potential as well as ATP synthesis in NSCs. It is also interesting to note that melatonin prevented oxidative stress caused by high levels of mitochondrial activity. Finally, we found that melatonin enriches NSC engraftment in the ND mouse model following transplantation. We concluded that a combined therapy involving transplantation of NSCs pretreated with pharmacological doses of melatonin could efficiently restore neuronal cell populations in PD and AD mouse models depending on mitochondrial activity promotion.

Accumulation of exogenous amyloid-beta peptide in hippocampal mitochondria causes their dysfunction: a protective role for melatonin.

Amyloid-beta (Aß) pathology is related to mitochondrial dysfunction accompanied by energy reduction and an elevated production of reactive oxygen species (ROS). Monomers and oligomers of Aß have been found inside mitochondria where they accumulate in a time-dependent manner as demonstrated in transgenic mice and in Alzheimer's disease (AD) brain. We hypothesize that the internalization of extracellular Aß aggregates is the major cause of mitochondrial damage and here we report that following the injection of fibrillar Aß into the hippocampus, there is severe axonal damage which is accompanied by the entrance of Aß into the cell. Thereafter, Aß appears in mitochondria where it is linked to alterations in the ionic gradient across the inner mitochondrial membrane. This effect is accompanied by disruption of subcellular structure, oxidative stress, and a significant reduction in both the respiratory control ratio and in the hydrolytic activity of ATPase. Orally administrated melatonin reduced oxidative stress, improved the mitochondrial respiratory control ratio, and ameliorated the energy imbalance.

ß-globin gene cluster haplotypes in sickle cell patients from Panamá.

OBJECTIVE: To analyze the frequency of the haplotypes of ß-globin gene cluster in randomly selected patients with sickle cell disease (SCD), attended in the Children's Hospital of Panama. METHODS: Five polymorphic sites in the ß-globin gene cluster were analyzed by polymerase chain reaction (PCR) followed by restriction digestion and agarose gel electrophoresis in a total of 100 patients, including 95 homozygous for HbS (sickle cell anemia) and 5 compound heterozygotes for HbS and HbC genes (HbSC disease). RESULTS: The Bantu haplotype was predominant with a frequency of 51%, followed by the Benin (30%), Senegal (8.5%), and Cameroon (4%); other haplotypes were also identified. Genotype was CAR/CAR in 39 patients, BEN/BEN in 22, SEN/SEN in 6, CAM/CAM in 4, ARB/ARB in 1, CAR/BEN in 15, CAR/SEN in 5, CAR/Hp5 in 3, CAR/Hp1 in 1, BEN/Hp11 in 1, Atp Hp1/Hp1 in 2, and Atp Hp5/Hp5 in 1 individual. Hemoglobin concentrations, hematocrit, and mean corpuscular hemoglobin concentration values did not differ among homozygous forms of haplotypes. The mean HbF in all patients was 15.39 ± 1.21, whereas SEN/SEN patients had higher HbF than BEN/BEN patients (24.26 ± 4.18 vs. 13.17 ± 2.39, respectively, P < 0.05). The percentage of reticulocytes was highest in BEN/BEN and CAR/CAR, and it was associated with worst prognosis. CONCLUSION: The results show the presence of common ß(S) haplotypes in Panama; the prevalence of African origin, and the similarity in the Panamanian and Colombian distribution of haplotypes.