We have tested the hypothesis that diaphragm muscle fibers release superoxide anion radicals (O2-.) into the extracellular space. Fiber bundles were isolated from rat diaphragm and incubated in Krebs-Ringer solution containing cytochrome c (10(-5) M), a standard assay for O2-.. Bundles were either passive or active, i.e., directly stimulated to contract rhythmically. After 1 h, absorbance of reduced cytochrome c in the incubation medium was measured at 550 nm. Absorbance was greater in medium exposed to passive muscle than in medium without muscle (P < 0.01), indicating O2-. release by passive muscle. Absorbance was greater in medium exposed to active muscle than in that exposed to passive muscle (P < 0.01), an increase inhibited by superoxide dismutase (10(3) U/ml). Active bundles fatigued; bundles developing the lowest final stresses produced the greatest absorbance increases (P < 0.001), suggesting that the magnitude of fatigue was inversely related to O2-. release. We conclude that O2-. is released by diaphragm myocytes into the interstitium and surrounding medium, a process accelerated by fatiguing muscular contractions.

We have previously shown that cytokines and postischemic cardiac lymph induce expression ofintercellular adhesion molecule-i (ICAM-1, CD54) on canine adult cardiac myocytes. ICAM-1 expression allows adherence of activated neutrophils to myocytes that is blocked by anti-CD18 mAb, R15.7, or anti-ICAM-1 mAb, CL18/6. Interleukin 1, tumor necrosis factora, or interleukin 6-stimulated cardiac myocytes were loaded with 2',7'-dichlorofluorescin, and oxidation to the fluorescent dichlorofluorescein was monitored. Fluorescence and neutrophil/myocyte adherence followed the same time course, and both were blocked by monoclonal antibodies to CD18, CD11b, and ICAM-1, but mAb R7.1, recognizing a functional epitope on CD1lla, was not inhibitory. The iron chelator, desferroxamine, and the hydroxyl radical scavenger, dimethylthiourea, did not inhibit neutrophil adherence, but completely inhibited fluorescence. In contrast, the extracellular oxygen radical scavengers superoxide dismutase and catalase, and the extracellular iron chelator, starch-immobilized desferroxamine, did not affect either fluorescence or adherence. Under the experimental conditions used, no superoxide production could be detected in the extracellular medium. Fluorescence microscopy demonstrated that fluorescence began within 5 min after neutrophil adherence to an individual myocyte, and myocyte contracture followed rapidly. Fluorescent intensity was highest initially at the site of myocyte-neutrophil adherence. When only neutrophils were loaded with 2',7T-dichlorofluorescein, fluorescence was observed only in those neutrophils adhering to the cardiac myocytes. Thus, adherence dependent on Mac-i (CD11b/ CD18) and ICAM-1 (CD54) activates the neutrophil respiratory burst resulting in a highly compartmented iron-dependent myocyte oxidative injury. (J. Clin. Invest. 1992. 90:1335-1345.) Key words: adhesion-dependent oxidative burst * Mac-1-ICAM-1 adhesion * neutrophil-induced myocyte injury compartmented myocyte oxidative injury

No abstract

Psoriasis is a chronic inflammatory skin disease in which epidermal proliferation is closely associated with excessive microvascular expansion within the papillary dermis. Angiopoietins have recently been identified as the major ligands of the endothelial- specific receptor Tie2. Angiopoietin 1 induces Tie2 signaling as a receptor activator and maintains blood vessel formation, whereas angiopoietin 2 destabilizes vessels by blocking Tie2 signaling as an antagonist of angiopoietin 1 and acts with vascular endothelial growth factor to initiate angiogenesis. In this study we examined the potential role of angiopoietins and the Tie2 receptor in vascular changes of psoriasis. Angiopoietin 1, angiopoietin 2, and Tie2 were upregulated in involved psoriasis skin compared to uninvolved psoriasis skin, healthy skin, and chronic spongiotic dermatitis skin. Angiopoietin 1 was expressed by stromal cells in the highly vascularized papillary dermis of involved psoriasis skin. Angiopoietin 2 was expressed by endothelial cells in the vicinity of the proliferating epidermis that abundantly expressed vascular endothelial growth factor. Vascular endothelial growth factor and basic fibroblast growth factor, which were overexpressed in involved psoriasis skin, enhanced angiopoietin 2 and Tie2 expression in dermal microvascular endothelial cell cultures. Thus, our findings suggest that upregulation of angiopoietin 1, angiopoietin 2, and Tie2 is closely associated with the development of microvascular proliferation in psoriasis, and that the angiopoietin-Tie2 system may act coordinately with vascular endothelial growth factor and basic fibroblast growth factor to promote neovascularization in psoriasis. Moreover, successful antipsoriatic treatment was accompanied by noticeable reduction of angiopoietin 2 expression, suggesting that alteration of angiopoietin 2 expression may be particularly important in controlling vascular proliferation in the treatment of psoriasis.

No abstract

Although the mechanisms of 5-fluorouracil (5-FU)-induced diarrhea remain unclear, accumulating evidence has indicated that changes in the mucosal immune system and aquaporins (AQPs) may play a role in its pathogenesis. Therefore, we investigated the possible changes in the gene expression of inflammatory cytokines and AQPs in the intestines of mice with 5-FU-induced diarrhea. In the present study, the expressions of mRNAs that encode inflammatory cytokines, TNF-α, IL-1β, IL-6, Il-17A and IL-22, were significantly increased throughout the entire colon of mice that exhibited diarrhea following 5-FU administration. In contrast, the gene expression of IFNγ was upregulated only in the distal colon. These increases were significantly reduced by the administration of etanercept. However, 5-FU-induced diarrhea was not recovered by etanercept. On the other hand, the genes for AQPs 4 and 8 were markedly present in the colon, and these expressions in the intestines were significantly decreased by treatment with 5-FU. These decreases were not reversed by etanercept. These findings suggest TNF-α neutralization had no effect on the acutely 5-FU-induced diarrhea and impaired AQPs but reduced dramatically several inflammatory cytokines.

No abstract

Eucophylline (1), a new tetracyclic vinylquinoline alkaloid, was isolated from the bark of Leuconotis eugenifolius together with leucophyllidine (2). The structure and absolute configuration of 1 were elucidated on the basis of 2D NMR correlations and simulated CD analysis. Leucophyllidine (2) showed iNOS inhibitory activity and decreased the iNOS protein expression dose-dependently.