Shigeru Sugino

Role of oxygen-derived free radicals in the pathogenesis of gastric mucosal lesions in rats.

The role of oxygen-derived free radicals and lipid peroxidation in the pathogenesis of acute gastric mucosal erosion was investigated in rat models produced by burn shock stress, by treatment with regional hyperthermia, platelet activating factor, and compound 48/80, and by ischemia-reperfusion. In all experimental models, the increase in the gastric erosions and in TBA reactants in the gastric mucosa were significantly inhibited by the treatment with superoxide dismutase (SOD) and/or catalase. Pretreatment with allopurinol, a competitive inhibitor of xanthine oxidase, prevented considerably the gastric injury (a) induced by burn shock, (b) produced by treatment with compound 48/80, and (c) caused by ischemia-reperfusion. By the treatment with anti-rat neutrophil antibody, the gastric mucosal injuries induced by regional hyperthermia, platelet activating factor, and compound 48/80 were significantly inhibited; however, burn shock and ischemia-reperfusion injuries were not inhibited. These results suggest that oxygen-free radical and lipid peroxidation contribute to the formation of gastric mucosal lesions, and that the sources of oxygen radicals seem to be different among these experimental models.

Role of Free Radicals and Lipid Peroxidation in Gastric Mucosal Injury Induced by Ischemia-Reperfusion in Rats

Ischemia and reperfusion is of the greatest importance in the pathology of various diseases. This study was designed to investigate the role of oxygen-derived free radicals and lipid peroxidation in gastric mucosal injury induced by ischemia-reperfusion in rats. Clamping of the celiac artery in rats reduced the gastric mucosal blood flow to 10% of that measured before the clamping. Gastric mucosal injury, such as spotty and linear hemorrhagic erosions, was seen in rats 60 min of the reperfusion following 30 min of ischemia. Thiobarbituric acid (TBA) reactants in the gastric mucosa were increased after the reperfusion. The increase in gastric mucosal lesions and TBA reactants were significantly inhibited by the treatment with SOD+ catalase and allopurinol. These results suggest that oxygen-derived free radicals and lipid peroxidation may play an important role in the pathogenesis of acute gastric mucosal lesions induced by ischemia-reperfusion.

Scavenging Effects of Aspalathus Linealis (Rooibos Tea) on Active Oxygen Species

Rooibos tea ia a totally unique South African product of the plantAspalathus linealis which is only produced in the Cadarberg mountains around Clanwilliam. In South Africa it is mainly used as a substitute for the Oriental black tea by people who enjoy it either hot or cold, or by those who regard it as a healthy drink. Clinically, Rooibos tea is often prescribed for nervous tension, allergies, stomach and digestive problems. For evaluation of its antioxidant action, reactivity of Aspalathus linealis, ascorbic acid, and quercetin which is one of non-glycosidically linked flavonoids included in Asparathus linealis, to various reactive oxygen species were assessed by electron spin resonance (ESR) sipectrometry using 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) as a spin trapper1,2.

Lipopolysaccharide-induced colitis in rabbits

SummaryAn experimental animal model of human ulcerative colitis using lipopolysaccharide (LPS) was studied. Rabbits were skin-sensitized by LPS and challenged with intrarectal instillation of LPS after 1% formalin enema. The course of experimental colitis was followed by performing serial colonofiberscopic examinations and biopsy. Petechiae appeared from the 8th hour, and ulcers and bleeding on the 3rd day. Mild macroscopic changes continued for about 2 weeks. By repeating the LPS enema after the initial treatment, the colitis was maintained for over 1 month. Control groups without formalin enema revealed no macroscopic changes, and the groups with only formalin enema showed mild transient changes. The endotoxin level in the blood during the experiment increased (36 pg/ml) at 24 h after the treatment in the LPS-sensitized group, while non-sensitized control rabbits had higher levels of endotoxin. Though fibrinogen and PTT levels had increased at 24 and 72 h, these levels were more marked in the control rabbits. The direct reaction of LPS was minimal, and local immune reaction by LPS seems to play an important role in the perpetuation of experimental colitis. Tissue fibrinolysis of the colon increased significantly as the mucosal damage appeared. This experimental colitis with LPS may be useful as a model of human ulcerative colitis.

Protection by Seleno-Organic Compound, Ebselen, Against Acute Gastric Mucosal Injury Induced by Ischemia-Reperfusion in Rats

Several pathogenetic mechanisms have been suggested to account for acute gastric mucosal injury. Recently, Oxigen-derived free radicals and lipid peroxidation have been suggested to play a role in the pathogenesis of gastric mucosal injury1,2,3). Ischemia and reperfusion are of the greatest importance in the pathology of many diseases. There has been great interest in the possible role of oxygen radical species in ischemia-reperfusion in the gastric mucosa4). A synthetic seleno-organic compound, 2-phenyl-1, 2 benzoisoselenazol-3(2H)-one(Ebselen), shows a glutathione peroxidase(GSHPx)-like activity-5,6). This study was designed to examine the protective effects of the agent, Ebselen against the gastric mucosal injury induced by ischemia-reperfusion.

Pathogenesis of platelet-activating factor-induced gastric mucosal damage in rats.

Platelet-activating factor (PAF), given intravenously, induced erosions and hyperemia to the rats stomachs. Gastric mucosal blood flow was decreased and thiobarbituric acid (TBA) reactants (an index of lipid peroxidation) in the gastric mucosa were increased 10 min after PAF injection. Superoxide dismutase plus catalase reduced the gastric mucosal lesions and TBA reactants, but had no influence on gastric mucosal blood flow. A reduction in the number of circulating polymorphonuclear leukocytes (PMN) reduced the gastric mucosal damage and TBA reactants, and inhibited the decrease in gastric mucosal blood flow, as observed 30 and 60 min after PAF injection. PAF induced superoxide production by rat PMN and enhanced that stimulated by opsonized zymosan or phorbol myristate acetate. These results suggest that microcirculatory disturbance and oxygen-derived free radicals generated by PMN play important roles in gastric mucosal lesions induced by PAF.

Treatment of malignant ascites and pleurisy by a streptococcal preparation OK-432 with fresh frozen plasma—a mechanism of polymorphonuclear leukocyte (PMN) accumulation

A single injection of a streptococcal preparation, OK-432, with fresh frozen plasma (FFP) (or fresh human serum) into the peritoneal or pleural cavity for the treatment of malignant ascites or pleurisy resulted in a complete reduction of ascitic fluid or pleural effusion in 5 out of 11 patients. FFP was used a further source of complement for the effective accumulation of antitumor polymorphonuclear leukocytes (PMNs) by complement-derived chemotactic factors in the cavity. C5a increased in the fluids 3-9 h after the injection and preceded a massive increase in PMNs. C1 inhibitor (C1INH) and C3b inactivator (C3bINA) decreased in several cases 6 h after the treatment. Chemotactic arachidonic acid metabolites, thromboxane B2(TXB2) as a characteristics of TXA2, and leukotriene B4(LTB4) also increased at the same time even in cases where C5a changed only minimally, and may play a role in accumulating antitumor PMNs in the cavity.

Treatment of cancer ascites by intraperitoneal administration of a streptococcal preparation OK-432 with fresh human complement--role of complement-derived chemotactic factor to neutrophils.

The role of complement in the polymorphonuclear leukocyte (PMN)-mediated tumor cell destruction in cancer ascites was investigated in relation to a streptococcal preparation OK-432, a so-called biological response modifier. Incubation of OK-432 with fresh human serum at 37 degrees C for 60 min resulted in the generation of C3a and C5a chemotactic factors. Intraperitoneal (i.p.) injection of the mixture to a patient with cancer ascites revealed an accumulation of PMNs in the ascitic fluid for a longer period with a rapid reduction of the ascitic fluid, than an intraperitoneal injection of OK-432 alone examined in the same patient. PMNs were found to invade clusters of the tumor cells and then form rosettes followed by the destruction of tumor cells. These findings induced by OK-432 continued over 10 days in the presence of fresh serum, while diminished within 3-4 days when OK-432 alone was injected. When fresh human plasma or fresh frozen plasma was used instead of serum and i.p. injected with OK-432 avoiding preincubation, the same cytological and clinical changes were observed in other patients. These data strongly indicate that OK-432 activates human complement either in vitro or in the peritoneal cavity, and induces PMNs to accumulate in the ascitic fluid. Although the mechanism of killing of tumor cells by PMNs is obscure, addition of human serum or plasma to i.p. use of OK-432 seems to be valuable for the management of patients with malignant ascites.

C3b receptor (CR1) on erythrocytes in various diseases

Abstract Complement receptor for C3b (CR1) on erythrocytes was investigated in various diseases by immune adherence hemagglutination (IAHA) using aggregated human IgG. In normal controls, 21 out of 312 (6%) revealed defective CR1 reactivity, and there was no difference in the prevalence of defective CR1 reactivity between female ( 11 157 , 7%) and male ( 10 155 , 6%). Among various diseases examined significantly high prevalence of defective reactivity of CR1 on erythrocytes was seen in systemic lupus erythematosus (SLE) ( 22 30 , 73%) and malignancy of hematopoietic system, especially in acute myelogenous leukemia (AML) ( 6 11 , 55%).

PSK and OK-432-induced immunomodulation of inducible nitric oxide (NO) synthase gene expression in mouse peritoneal polymorphonuclear leukocytes and NO-mediated cytotoxicity.

Abstract We investigated whether PSK (a polysaccharide from the mycelia of Coriolus versicolor) or OK-432 (a streptococcal preparation) can up-regulate inducible nitric oxide synthase (iNOS) gene expression and nitric oxide (NO) production in mouse peritoneal polymorphonuclear leukocytes (PMNs). Six hrs after intraperitoneal injection of mice with PSK (2500 μg/mouse) or OK-432 (100 μg/mouse), mouse peritoneal PMNs were restimulated with PSK (500 μg/ml) or OK-432 (10 μg/ml) plus 100 U/ml of mouse interferon-gamma (IFN-γ) in vitro. Northern blot analysis showed strong synergism between both PSK and OK-432 and IFN-γ for the induction of iNOS gene expression. NO production by PMNs was increased up to 20 μM (2 μM/106 PMNs/24 hrs) as measured by the Griess reagent method when PMNs were restimulated with PSK or OK-432 plus IFN-γ for 24 hrs, although tumor cell killing was not detected. NO concentrations of more than 80 μM were required for P815 tumor cell killing. These results suggest that PMNs produce NO after stimulation with PSK or OK-432 in combination with IFN-γ and may regulate the immune system in vivo, although the NO production induced by these agents is insufficient for tumor cell killing in vitro.