Intraluminal pCO2: A reliable indicator of intestinal ischemia

A reliable, objective method to determine small bowel ischemia intraoperatively has not been developed. These experiments examined the relationship between intraluminal pCO2 (IL pCO2), intestinal blood flow, and degree of ischemic mucosal injury. IL pCO2 was measured with a clinical mass spectrometer using Teflon catheters calibrated in tissue mode; transmural intestinal blood flow was measured with radioactive microspheres. Anesthetized rabbits (N = 24) were cannulated for microsphere injections and mass spectrometer catheters were placed in the lumen of the small bowel. Blood flow was determined prior to superior mesenteric artery occlusion and then at 30, 60, or 180 min after occlusion. In control animals the superior mesenteric artery was not clamped. Intestinal biopsies were taken at the time of each blood flow determination and microscopic injury was graded from 1 (normal) to 4 (complete epithelial slough). There was a strong linear correlation between the IL pCO2 and the histologic grade of injury (r = 0.778, P \u3c 0.001). These results show that intestinal ischemia due to superior mesenteric artery occlusion causes a rapid, sustained rise in small bowel IL pCO2 that correlates with the degree of mucosal injury. These experiments suggest that this technology may provide a superior method to assess intestinal perfusion. © 1985

Effects of NMDA receptor antagonists following spinal ischemia in the rabbit

Evidence has accumulated to implicate the excitatory amino acid neurotransmitters, glutamate and aspartate, in the pathophysiology of central nervous system (CNS) ischemic injury. It appears from both in vivo and in vitro experiments that they exert their excitotoxic effects in CNS ischemia by their actions at the N-methyl- d-aspartate (NMDA) receptor complex. In the present study, we examined the effects of MK-801 and ketamine, two noncompetitive NMDA receptor antagonists, in a model of spinal cord ischemia in conscious rabbits produced by occluding the infrarenal aorta for 25 min. Five minutes after reperfusion, animals were treated with either saline, ketamine, or MK-801. By 6 h postreperfusion, all treatment groups exhibited an initial recovery of hindlimb motor function, after which the saline- and ketamine-treated groups had a similar progressive deterioration in function over the next 48 h. However, the MK-801-treated rabbits continued to recover motor function such that neurological scores in these rabbits were significantly improved relative to those of the saline-treated animals at 48 h. Histopathological evaluation showed that MK-801-treated rabbits tended to have a lesser degree of central gray matter necrosis. These results indicate that MK-801 protected against the secondary deterioration associated with this model and strengthen the potential therapeutic use of NMDA receptor antagonists in the treatment of CNS ischemia

Continuous improvement in the immune system of HIV-infected children on prolonged antiretroviral therapy

BACKGROUND: The goal of HAART is to promote reconstitution of CD4(+) T cells and other immune responses. We evaluated the extent and the kinetics of immune reconstitution in HIV-infected children over 144 weeks of successful HAART. METHODS: Thirty-seven children receiving their first HAART regimen had plasma HIV RNA; T cells and subpopulations; T-cell rearrangement excision circles (TREC) DNA; candida, HIV(CD4) and HIV(CD8) enzyme-linked immunospot measured at regular intervals. RESULTS: Plasma HIV RNA became undetectable in 81% of patients at 24 weeks and remained undetectable in 77% at 144 weeks. In contrast, CD4(+)% continuously increased. Distribution of T-cell subpopulations changed rapidly during the first 48 weeks of HAART and more slowly thereafter. At 144 weeks, total, naive and activated CD4(+)% and naive CD8(+)% of HIV-infected children were not significantly different from those of healthy age-matched controls, whereas total and activated CD8(+)% remained elevated. CD4(+) and CD8(+) TREC content increased only during the first 48 weeks of HAART. They positively correlated with each other and with total CD4(+)%, naive CD4(+)% and naive CD8(+)%. Candida and HIV(CD4) enzyme-linked immunospot increased over time reaching peak values at 48 weeks and 144 weeks, respectively. HIV(CD8) enzyme-linked immunospot decreased in magnitude over 144 weeks of HAART but retained its breadth. Baseline CD4(+)% positively correlated with CD4(+)% and with functional immune reconstitution at week 144, whereas baseline TREC correlated with TREC at week 144. CONCLUSION: HIV-infected children acquired normal distribution of CD4(+) T cells and other subpopulations and recovered CD4-mediated HIV immunity after 144 weeks of HAART

Effects of team goal interdependence on newcomer socialization : an experiment in China

Increased employee mobility and the widespread use of teams underline the importance of understanding the socialization of newcomers into groups. Applying the theory of cooperation and competition, this study experimentally investigated the relationship between team climate and newcomer socialization and performance. We found that a cooperative, in comparison to a competitive or independent team climate strengthened the relationship and interaction between newcomers and the other team members. Thereby, this facilitated newcomer socialization