烫伤大鼠结肠动力基本功能单位细胞损害和内质网应激研究

Objective To observe expressions of glucose-regulated protein (GRF78) and caspase-12 in nervous system-interstitial cells of Cajal (ICC) in smooth muscle in colonic wall in rats with scald inju-ry, as well as their relevant ultrastructural changes, so as to probe the possible mechanisms of dynamic dam-age in murine colon after a scald injury. Methods Fifty healthy Sprague-Dawley rats were randomly di-vided into scald (n =40) and control (n = 10) groups. Rats in scald group were inflicted with 30% TBSA full-thickness scald, and received an intraperitoneally injection of Ringer lactate solution (50 mg/kg) for re-suscitation, while those in control group had similar treatment with the exception of scald. Rats in control group and scald group were sacrificed at 3, 6, 12, 24 post scald hour ( PSH, 10 rats at each time point) for collection of 4 cm of colonic tissue, 5 cm proximal to the cecum. A segment of colonic wall, 1 cm in length, was obtained from the middle of the harvested segment of colon, and it was fixed with 3% glutaraldebyde or 10% formaldehyde. The samples fixed with glutaraldehyde were used to observe uhrastructural alterations under transmission electron microscope, while that with formaldehyde were used to observe expressions of GRP78 and caspase-12 in colonic wall by immunohistochemical assay. Results The colonic smooth mus-cle cells of rats in control group showed regular arrangment, their organelles were abundant, nucleus central-ly located, euchromatin distributed evenly with more abundant mitochondrial cristae and less smooth endo-plasmic reticulum, neuronal organelles were abundant in intermuscular plexus, and ICC could be seen in the neighborhood of neurons. The colonic smooth muscle cells appeared in irregular and disordered manner in scald group, perinuclear space was widened, intercellular vacuoles were observed, mitochondria showed vac-uolation degeneration with dissolved and condensed cristae, rough endoplasmic reticula were dilated with par-tial dissolution, and perinuclear cytoplasm of ICC was obviously decreased. The expression of GRP78 was increased in scald group at 3, 6, 12 PSH (4.3±0.9, 6.0±0.7,4.8±1.1 score) as compared with that in control group ( 2.4±0.7 score, P<0.05 ). The expression of caspase-12 in scald group at 6, 12, 24 PSH was higher than that in control group (P<0.05). GRP78 was consistantly expressed in cytoplasm in con-trol group, while in scald group, it mainly appeared in mucosa, myenteric plexus, and stromal cells, but on-ly moderately or lightly expressed in smooth muscle cells. The expression of GRP78 was positive in scald group at 3, 6, 12 PSH, strongly positive at 6 PSH, and it was also expressed in cytoplasm in control group. The expression of caspase-12 in scald group was not obviously positive at 3 PSH, and weakly positive at 6, 24 PSH, but strongly positive at 12 PSH, while no expression was shown in control group. Conclusions Marked pathological changes are observed in enteric nervous system-interstitial cells of Cajal-smooth muscle in rats with severe scald injury. It may be related with cellular injuries induced by caspase-12 apoptotic path-ways through activated endoplasmic reticulum stress.     

"Free" and "exchangeable" or "trapped" and "non-exchangeable" water in cartilage

We repeated some of our own previous experiments, as well as some of Torzilli's recent experiments (11) on which he bases his conclusions relating to a nonexchangeable "trapped water" in cartilage. We are unable to confirm Torzilli's findings. We observed partition coefficients for 3H.HO very close to unity. That both the extrafibrillar and most of the intrafibrillar water is freely exchangeable and behaves as available water towards small solutes has been independently shown (3) for other collagenous tissues. All the different permutations of partition experiments have yielded results that are fully consistent with our original picture of the very major fraction of cartilage water being free.     

Spatiotemporal analysis of auditory "what" and "where" working memory

Goal-directed attention to sound identity (what) and sound location (where) has been associated with increased neural activity in ventral and dorsal brain regions, respectively. In order to ascertain when such segregation occurs, we measured event-related potentials during an n-back (n = 1, 2) working memory task for sound identity or location, where stimuli selected randomly from 3 semantic categories (human, animal, music) were presented at 3 possible virtual locations. Accuracy and reaction times were comparable in both "what" and "where" tasks, albeit worse for the 2-back than for the 1-back condition. The partial least squares analysis of scalp-recorded and source waveform data revealed domain-specific activity beginning at about 200-ms poststimulus onset, which was best expressed as changes in source activity near Heschl's gyrus, and in central medial, occipital medial, right frontal and right parietal cortex. The effect of working memory load emerged at about 400-ms poststimulus and was expressed maximally over frontocentral scalp region and in sources located in the right temporal, frontal and parietal cortices. The results show that for identical sounds, top-down effects on processing "what" and "where" information is observable at about 200 ms after sound onset and involves a widely distributed neural network.     

"Gas off" or "vaporizer off"

Editor—It is a common misconception that turning off thevaporizer while leaving the fresh gas flow (FGF) on, during