RNA m6A methylation and regulatory proteins in pulmonary arterial hypertension

m6A (N6‑methyladenosine) is the most common and abundant apparent modification in mRNA of eukaryotes. The modification of m6A is regulated dynamically and reversibly by methyltransferase (writer), demethylase (eraser), and binding protein (reader). It plays a significant role in various processes of mRNA metabolism, including regulation of transcription, maturation, translation, degradation, and stability. Pulmonary arterial hypertension (PAH) is a malignant cardiopulmonary vascular disease characterized by abnormal proliferation of pulmonary artery smooth muscle cells. Despite the existence of several effective and targeted therapies, there is currently no cure for PAH and the prognosis remains poor. Recent studies have highlighted the crucial role of m6A modification in cardiovascular diseases. Investigating the role of RNA m6A methylation in PAH could provide valuable insights for drug development. This review aims to explore the mechanism and function of m6A in the pathogenesis of PAH and discuss the potential targeting of RNA m6A methylation modification as a treatment for PAH.

[Dynamic changes of axial length, corneal refractive power, and refractive state after cataract surgery in infants]

Objective: To investigate the changes of axial length, corneal refractive power, and refractive state in infants with congenital cataract surgery. Methods: Retrospective cohort study. Medical records of 103 patients who underwent congenital cataract surgery in the Eye Hospital of Wenzhou Medical University Hangzhou Branch from January 1, 2015 to December 31, 2018 were reviewed. There were 61 boys and 42 girls in the study. The mean age at the surgery of 103 congenital cataract patients was (3.95±1.94) months. In patients receiving bilateral cataract surgery, only the left eye was selected for analysis. The patients were followed up for at least 1 year. The patients were divided into the groups of <4 months old and 4-12 months old according to the age at cataract surgery. The change in the axial length, corneal refractive power, and refractive state of each patient at 1 year after surgery was analyzed. Independent sample t-test, one way variance analysis and simple linear regression were used for statistical analysis. Results: There were 71 cases of bilateral cataract, including 33 in the group of <4 months old and 38 in the group of 4-12 months old, and 32 cases of unilateral cataract, including 17 in the group of <4 months old and 15 in the group of 4-12 months old. The change in the axial length of bilateral cataract children in the <4-month-old group was (2.46±1.33) mm at 1 year after surgery, which was greater than (1.52± 1.00) mm in the group of 4-12 months old (t=3.21; P<0.01). In the same surgery age group, there was no significant difference in the change of axial length among bilateral cataract eyes, unilateral cataract eyes and the contralateral eyes at 1 year after surgery (both P>0.05). One year after surgery, the axial length of the eyes in patients with bilateral cataract, the affected eyes and the fellow eyes in patients with unilateral cataract all was highly correlated with the logarithm of the actual age (r=0.68, 0.52, 0.73; all P<0.01). The corneal refractive power showed a decreased trend with the increase of age. The change in the corneal refractive power of the bilateral cataract children in the <4-month-old group at 1 year after surgery was (1.43±2.87) D, and in the group of 4-12 months old was (0.68±2.10) D, but the difference was not statistically significant (P>0.05). The chang in spherical equivalent of bilateral cataract children was (2.02±2.60) D in the <4-month-old group, greater than that in the group of 4-12 months old [(0.69±1.89) D; t=2.15; P<0.05]. The change of spherical equivalent one year after surgery in 4-12 months group, unilateral cataract eyes was significantly greater than that of bilateral cataract eyes [(2.05±0.95) D vs. (0.69±1.89) D; t=2.49; P<0.05]. The spherical equivalent of both bilateral and unilateral cataract children was highly correlated with the actual age (r=-0.51, -0.54; both P<0.01). Conclusions: The axial length is increased, the corneal refractive power is decreased, and the spherical equivalent is decreased at 1 year after surgery for congenital cataract in infants. The younger the age at cataract surgery, the greater the change in the axial length, myopia drift, and corneal refractive power. (Chin J Ophthalmol, 2021, 57: 34-40).