Biomedical subjects

Li-Ling Wang

Publications and source records attributed to Li-Ling Wang.

2 recordsLinked to original sources

PubMed2004

Potential of peroxynitrite to promote the conversion of oxyhemoglobin to methemoglobin.

Superoxide anion and NO can react to form the highly oxidizing species peroxynitrite (ONOO-) which can react directly with hemoglobin (Hb) even in the presence of physiological concentration CO2. This research was to determine the ONOO- -mediated oxidation damage to the heme of oxyhemoglobin (oxyHb) under conditions expected in blood. Results showed that 8-10 mol ONOO- was needed to quickly and completely convert 1 mol oxyHb to methemoglobin (metHb). ONOO- (20-140 microM) caused rapid and extensive formation of metHb from oxyHb (50 microM) mainly occurring within first 5-20 min of incubation. The conversion efficiency reached 16%, 48%, 60%, 79% and 88% output of metHb after 90 min of incubation at 0, 20, 40, 100, and 140 microM ONOO- respectively. 1 mM CO2 caused a small decrease in the ability of ONOO- to oxidize oxyHb, and ONOO- -promoted conversion of oxyHb to metHb increased when pH decreased from 8.0 to 6.0. Relatively lower temperature in blood condition will inhibit this reaction in some degree. We postulate that ONOO- can mediate oxidation damage to the heme, and cause heme loss from the hydrophobic cavity of Hb when its concentration exceeded 90 microM. These results indicated that ONOO- could convert oxyHb to metHb under the conditions expected in blood, and this reaction was regulated by CO2 concentration, reaction time, temperature and pH value.

1-Butanol↗

PubMed2004

Root border cell development is a temperature-insensitive and Al-sensitive process in barley.

In vivo and in vitro experiments showed that border cell (BC) survival was dependent on root tip mucigel in barley (Hordeum vulgare L. cv. Hang 981). In aeroponic culture, BC development was an induced process in barley, whereas in hydroponic culture, it was a kinetic equilibrium process during which 300-400 BCs were released into water daily. The response of root elongation to temperatures (10-35 degrees C) was very sensitive but temperature changes had no great effect on barley BC development. At 35 degrees C, the root elongation ceased whereas BC production still continued, indicating that the two processes might be regulated independently under high temperature (35 degrees C) stress. Fifty microM Al could inhibit significantly BC development by inhibiting pectin methylesterase activity in the root cap of cv. 2000-2 (Al-sensitive) and cv. Humai 16 (Al-tolerant), but 20 microM Al could not block BC development in cv. Humai 16. BCs and their mucigel of barley had a limited role in the protection of Al-induced inhibition of root elongation, but played a significant role in the prevention of Al from diffusing into the meristems of the root tip and the root cap. Together, these results suggested that BC development was a temperature-insensitive but Al-sensitive process, and that BCs and their mucigel played an important role in the protection of root tip and root cap meristems from Al toxicity.

Aluminum↗