The effect of hyperosmosis on paracellular permeability in Caco-2 cell monolayers.

The intestinal epithelium is a significant barrier to oral absorption of hydrophilic compounds, and their passage through the intercellular space is restricted by the tight junctions. In this study we found that hyperosmosis is a significant factor altering paracellular transport in Caco-2 cell monolayers. Osmotic regulators, such as sodium chloride, mannitol, and raffinose, decreased transepithelial electrical resistance and enhanced lucifer yellow permeability. The effect of these osmotic regulators on Caco-2 cell monolayers was not likely to be caused by gross cytotoxicity. Although certain amino acids and oligosaccharides have been reported to have specific tight junction-modulating activity, we found that the increased paracellular permeability of Caco-2 monolayers induced by these compounds was at least partly due to the increased osmotic pressure of the test solutions. These findings provide a new potential precaution in the evaluation of paracellular permeability-modulating substances using the Caco-2 cell monolayer system.

Quantitative videographic analysis of blink patterns of newscasters.

BACKGROUND: To determine the blink patterns of newscasters. METHODS: The blink patterns of 39 professional newscasters (24 Japanese and 19 non-Japanese, 19 men and 20 women, mean age: 34.5 +/- 6.5 years) were analyzed by a blink analyzer in this observational case series. Sixty-four normal Japanese volunteers (35 men and 29 women, mean age: 31.2 +/- 7.6 years) were used as lay normal controls. RESULTS: The maximum, mean, and coefficient of variation (CV) of interblinking time (IBT: the time between one blink and the next) in newscasters were 2.36 +/- 0.90 s (P < 0.0005), 0.95 +/- 0.27 s (P < 0.0005), and 0.76 +/- 0.25 (P < 0.0005), respectively, while those of the controls were 8.87 +/- 3.96 s, 4.01 +/- 2.05 s, and 0.55 +/- 0.21, respectively. The maximum, mean, and CV of the blinking time (BT: the length of time for each blink) of newscasters were 0.71 +/- 0.43 s (P < 0.0005), 0.29 +/- 0.11 s (P < 0.0005), and 0.55 +/- 0.25 (P < 0.0005), respectively. The values were longer when compared with normal controls, which were also significantly different, 0.35 +/- 0.12 s, 0.20 +/- 0.04 s and 0.23 +/- 0.09, respectively. CONCLUSIONS: The six blink-related factors varied between newscasters and normal controls. Newscasters blink more often with greater irregularity.