ABSTRACT
We aimed to clarify the effects of cold stimulation at various temperatures on mitochondrial activity and vascular endothelial growth factor (VEGF) expression in vitro. Human fibroblast, human mesenchymal stem cell, and rat skeletal muscle myoblast cell lines were used. For each cell type, cells were divided into 4 groups and stimulated in various cold temperatures (0, 4, 17 and 25°C) 3 times for 15 min each by placement on crushed ice or floating on cold water set at each temperature. Control cells were subjected to warm water at 37°C. Factors related to mitochondrial activity, mitochondrial DNA copy numbers, and VEGF expression were analyzed 24 h after the last cold stimulation. In all cell types, significant increases of factors related to mitochondrial activity and mitochondrial DNA copy numbers were seen in the 4°C and 17°C-stimulated cells compared with control cells. In rat skeletal muscle cells stimulated at 4°C, VEGF expression significantly increased compared to the control cells. Our data suggest that cold stimulation at certain temperatures promotes mitochondrial activity, biogenesis and VEGF expression.
Subject(s)
Cold Temperature , DNA, Mitochondrial/metabolism , Mitochondria/metabolism , Vascular Endothelial Growth Factor A/genetics , Animals , Cell Line , Fibroblasts/metabolism , Gene Expression Regulation , Humans , Mesenchymal Stem Cells/metabolism , Myoblasts, Skeletal/metabolism , Rats , TemperatureABSTRACT
Slit-lamp examination of 78 cases of xerophthalmia and 29 controls matched for age, sex, and locale indicated a direct correlation between the presence, density, and extent of punctate epithelial keratopathy and the severity of corneal and noncorneal involvement. Only 7% (four or 58) of control eyes but 60% (six of ten) of cases with confirmed night blindness, 75% (47 of 63) of eyes with conjunctival xerosis, and all eyes with corneal xerosis (47) were affected. Within one week of high-dose systemic vitamin A therapy all affected corneas had improved. None of ten patients receiving low-dose systemic therapy showed any improvement over a two-month period, whereas 61% of involved corneas actually deteriorated in the interim. Punctate epithelial keraptopathy appears to be the earliest corneal manifestation of xerophthalmia, and is already present in the vast majority of cases classically considered free of corneal involvement.
