Histological validation of atrial structural remodelling in patients with atrial fibrillation.

BACKGROUND AND AIMS: This study aimed to histologically validate atrial structural remodelling associated with atrial fibrillation. METHODS AND RESULTS: Patients undergoing atrial fibrillation ablation and endomyocardial atrial biopsy were included (n = 230; 67 ± 12 years old; 69 women). Electroanatomic mapping was performed during right atrial pacing. Voltage at the biopsy site (Vbiopsy), global left atrial voltage (VGLA), and the proportion of points with fractionated electrograms defined as ≥5 deflections in each electrogram (%Fractionated EGM) were evaluated. SCZtotal was calculated as the total width of slow conduction zones, defined as regions with a conduction velocity of <30 cm/s. Histological factors potentially associated with electroanatomic characteristics were evaluated using multiple linear regression analyses. Ultrastructural features and immune cell infiltration were evaluated by electron microscopy and immunohistochemical staining in 33 and 60 patients, respectively. Fibrosis, intercellular space, myofibrillar loss, and myocardial nuclear density were significantly associated with Vbiopsy (P = .014, P < .001, P < .001, and P = .002, respectively) and VGLA (P = .010, P < .001, P = .001, and P < .001, respectively). The intercellular space was associated with the %Fractionated EGM (P = .001). Fibrosis, intercellular space, and myofibrillar loss were associated with SCZtotal (P = .028, P < .001, and P = .015, respectively). Electron microscopy confirmed plasma components and immature collagen fibrils in the increased intercellular space and myofilament lysis in cardiomyocytes, depending on myofibrillar loss. Among the histological factors, the severity of myofibrillar loss was associated with an increase in macrophage infiltration. CONCLUSION: Histological correlates of atrial structural remodelling were fibrosis, increased intercellular space, myofibrillar loss, and decreased nuclear density. Each histological component was defined using electron microscopy and immunohistochemistry studies.

Protective effects of raw and cooked blackcurrant extract on DNA damage induced by hydrogen peroxide in human lymphoblastoid cells.

CONTEXT: Blackcurrant (Ribes nigrum L.) is a classical fruit that has long been used to make juice, liqueur and sometimes medicines in Europe. The beneficial effects of blackcurrant, which are inhibition of lipopolysaccharide-stimulated inflammatory, anticarcinogenesis and other health effects, have been reported. OBJECTIVE: Previously, we reported the antimutagenic activities of blackcurrant using a yeast gene mutation assay. In this study, we investigated whether this antimutagenicity of blackcurrant was confirmed in human cells. MATERIALS AND METHODS: We prepared four types of aqueous blackcurrant extracts (BCE) from mature and premature with or without heat treatment by microwave. Antioxidant activities of BCE were measured by the DPPH radical scavenger assay. In the DPPH radical scavenger assay, the maximum concentration of BCE was 1.6 mg/reaction. We investigated the antigenotoxic activities of BCE by the comet assay and micronucleus test using the human lymphoblastoid cell line TK6. In the comet assay, TK6 was treated with 300 µM H2O2 without or with BCE at concentrations of 0.5, 1.0, 2.0 and 3.0 mg/mL. In the micronucleus test, TK6 was treated with 1 mg/mL BCE without or with H2O2. RESULTS: All BCEs exhibited more than 90% of inhibition rates of DPPH radicals at the maximum concentration of BCE. DNA damage and micronuclei induced by H2O2 significantly decreased in the each BCE-treated condition. CONCLUSION: The results suggest that BCE treatment can reduce the genomic instability induced by H2O2 in human cells. We consider that these antigenotoxic effects are related to polyphenols, l-ascorbic acid and other antioxidant compounds.