Summary of the MAIA Working Conference Bradley, M Patricia; Brown, Barbara S; Hale, Stephen S ...
Environmental monitoring and assessment,
07/2000, Letnik:
63, Številka:
1
Journal Article
Statin drugs and various isoprenoids from plant origins inhibit mevalonic acids, cholesterol, and other isoprenoid products. Among these, reduction of farnesyl and geranylgeranyl prenylated proteins ...impedes signal transduction at the cellular level. The authors envision that limiting such prenylated proteins downregulates thrombin-stimulated events, including decreasing the expression and availability of protease-activated receptor-1 mitigating thrombin stimulation of cells, tissue factor preventing additional thrombin generation, and plasminogen activator inhibitor-1 allowing thrombosis. Additional processes may enhance nitric oxide production and induce other processes. Downregulation of thrombin-stimulated events should promote hypothrombotic or quiescent conditions that reduce cardiovascular disease, thus contributing to longevity.
Adhesion of leukocytes (L) to microvascular endothelium (E) is a required step in the L–E interaction leading to tissue injury in ischemia–reperfusion. To assess the optimum period for therapy aimed ...at ameliorating negative effects of this required step, we investigated the time course of L–E adhesion in the hamster cheek pouch using 2 hr of ischemia and 1 hr of reperfusion in our model of I–R injury (Am. J. Physiol.261: 1626, 1991). Leukocytes adhering (stationary for ≥30 sec) to postcapillary venules (15–30 μm in diameter) were counted after labeling with acridine orange. Prior to the induction of ischemia, there were no significant differences in the number of adherent leukocytes in each area chosen for study (1.9 ± 0.6 vs 2.0 ± 0.3; mean number of leukocytes/100-μm vessel length ± SD). After 10 and 20 min of reperfusion there was no significant difference in leukocyte adhesion in the ischemic area relative to the control (2.7 ± 0.5 vs 2.8 ± 0.8, and 5.3 ± 2.8 vs 2.4 ± 0.6, respectively). Leukocyte adherence increased significantly after 30 min of reperfusion and remained elevated at 1 hr of reperfusion in the postischemic area relative to the nonischemic control area (7.8 ± 1.3 vs 3.6 ± 0.6, and 8.3 ± 0.8 vs 4.1 ± 0.6, respectively;P< 0.01). Leukocyte adhesion in the postischemic area after 30 min reperfusion was not significantly different from the adhesion at the end of 1 hr reperfusion. These data suggest that (1) peak leukocyte adhesion occurs after 30 min of normal reperfusion and (2) postischemic therapeutic intervention may be most beneficial when instituted within this early time period.
Background. Interaction of the CD11/CD18 complex on polymorphonuclear neutrophils (PMNs) and intercellular adhesion molecule (ICAM)-1 on endothelium is a critical event in PMN-mediated tissue injury. ...In addition, increased expression of ICAM-1 on type I pneumocytes has been identified in a variety of pulmonary disorders associated with PMN-induced inflammation. We hypothesized that ICAM-1 up-regulation is sufficient to promote cytotoxicity via activated PMNs.
Methods. The complementary DNA for human ICAM-1 was transfected into Chinese hamster ovarian (CHO) cells, which do not inherently express this adhesion receptor, by using the expression vector CD1.8. Fluorescence-activated cell sorter analysis revealed 62% CHO cell surface expression of ICAM-1. Wild type and transfected CHO cells were labeled with chromium 51 and exposed to quiescent or activated (1 μmol/L phorbol myristate acetate) PMNs for 4 hours. Subsets were pretreated with a monoclonal antibody to ICAM-1. PMN cytotoxicity was determined by specific percent
51Cr release.
Results. Incubation of quiescent PMNs with wild type and transfected CHO cells produced nominal cell lysis, 0.5%±0.3% and 0.2%±0.2%, respectively. Activated PMNs produced 13.6%±3.2% versus 1.4%±0.7% cell lysis, comparing transfected with wild type CHO cells, and 0.5%±0.2% cell lysis after pretreatment with a monoclonal antibody to ICAM-1, p<0.01.
Conclusions. ICAM-1 up-regulation is sufficient to promote cytotoxicity via activated PMNs. This may represent a potential target for attenuating PMN-mediated injury to endothelial and other cell lines, including parenchyma.
Reviews of Books LeDonne, John P.; Gerberding, Richard A.; Morris, Richard ...
International history review,
06/2005, Letnik:
27, Številka:
2
Journal Article
One to four alanines were inserted by site-directed mutagenesis at three different locations within the alpha-helix comprising residues 39 to 50 in bacteriophage T4 lysozyme. All insertion mutants ...were correctly folded and catalytically active although the insertions led to a thermal destabilization by 1.1 to 4.2 kcal/mol when compared to wild-type. Variants that restored part of the loss in stability associated with the initial alanine insertions could be found by randomizing the inserted amino acids. In selected cases, directed mutagenesis of adjacent residues was also used to regain stability. Structural information obtained from X-ray crystallography and/or 2D-NMR for 10 different variants showed two distinct ways in which the protein responded to the amino acid insertions: (1) The inserted amino acids were incorporated into the helix by replacing preceding wild-type amino acids and causing a shift in register towards the N terminus. As a consequence, wild-type amino acids were translocated from the helix into the preceding loop. (2) Insertions caused a "looping out" within the alpha-helix. In this case the perturbation was confined to a minimal region in the immediate vicinity of the insertion. No change in the length of the helix was detected in either case. The structural response appears to be determined by the maintenance of the hydrophobic interface between the helix and the rest of the protein. This interface remains essentially intact in all variant structures. The results exemplify the plasticity and the adaptability of the protein structure which allows the incorporation of additional amino acids into a secondary structure element without large structural perturbations, as long as vital internal interactions are preserved. They also suggest that loops in proteins related by evolution can vary in length not only because of insertions within the loops themselves but also as a consequence of insertions within neighboring secondary structure elements.
The National Institute for Engineering Ethics has produced a new video that dramatizes a fictional but realistic case in which an engineer addresses numerous ethical issues in designing a new ...chemical plant in Mexico. In a special session at the conference, participants will learn to use a new video to teach professional and ethical issues in engineering effectively, with two basic cooperative learning techniques: generating questions in pairs and structured discussions in small groups.
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