RESUMEN
Bovine CuZnSOD was used during an 8-year period as an anti-inflammatory drug in 26 patients with severe Crohn's disease, usually after failure of corticotherapy, or when this drug was avoided because of side-effects or abscesses. This was a Phase II trial during which doses, routes of administration and concomitant therapies were progressively modified. The acceptability was excellent with the free enzyme. We obtained 19/26 very good short term responses, and 82% good results on long term evolution. The efficacy of SOD as an anti-inflammatory drug in Crohn's disease needs to be confirmed by controlled trials.
Asunto(s)
Enfermedad de Crohn/tratamiento farmacológico , Deferoxamina/uso terapéutico , Superóxido Dismutasa/uso terapéutico , Adolescente , Adulto , Anciano , Ensayos Clínicos como Asunto , Quimioterapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Superóxido Dismutasa/efectos adversosRESUMEN
Oxidative stress is now recognized as accountable for redox regulation involving reactive oxygen species (ROS) and reactive nitrogen species (RNS). Its role is pivotal for the modulation of critical cellular functions, notably for neurons astrocytes and microglia, such as apoptosis program activation, and ion transport, calcium mobilization, involved in excitotoxicity. Excitotoxicity and apoptosis are the two main causes of neuronal death. The role of mitochondria in apoptosis is crucial. Multiple apoptotic pathways emanate from the mitochondria. The respiratory chain of mitochondria that by oxidative phosphorylation, is the fount of cellular energy, i.e. ATP synthesis, is responsible for most of ROS and notably the first produced, superoxide anion (O(2)(;-)). Mitochondrial dysfunction, i.e. cell energy impairment, apoptosis and overproduction of ROS, is a final common pathogenic mechanism in aging and in neurodegenerative disease such as Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS). Nitric oxide (NO(;)), an RNS, which can be produced by three isoforms of NO-synthase in brain, plays a prominent role. The research on the genetics of inherited forms notably ALS, AD, PD, has improved our understanding of the pathobiology of the sporadic forms of neurodegenerative diseases or of aging of the brain. ROS and RNS, i.e. oxidative stress, are not the origin of neuronal death. The cascade of events that leads to neurons, death is complex. In addition to mitochondrial dysfunction (apoptosis), excitotoxicity, oxidative stress (inflammation), the mechanisms from gene to disease involve also protein misfolding leading to aggregates and proteasome dysfunction on ubiquinited material.
Asunto(s)
Encéfalo/metabolismo , Enfermedades Neurodegenerativas/metabolismo , Estrés Oxidativo/fisiología , Animales , Encéfalo/patología , Muerte Celular/fisiología , Humanos , Enfermedades Neurodegenerativas/patologíaRESUMEN
Iron has the capacity to accept and donate electrons readily. This capability makes it physiologically essential, as a useful component of cytochromes and oxygen-binding molecules. However, iron is also biochemically dangerous; it can damage tissues by catalyzing the conversion of hydrogen peroxide to free-radical ions that attack cellular membranes, protein and DNA. This threat is reduced in the healthy state where, because of the fine iron metabolism regulation, there is never appreciable concentration of 'free iron'. Under pathological conditions, iron metabolism and superoxide metabolism are clearly interactive. Each can exacerbate the toxicity of the other. Iron overload may amplify the damaging effects of superoxide overproduction in a very broad spectrum of inflammatory, both acute and chronic, conditions. Furthermore, chronic oxidative stress may modulate iron uptake and storage, leading to a self-sustained and ever-increasing spiral of cytotoxic and mutagenic events. The iron chelator deferroxamine is able to chelate 'free iron' even inside the cell. Its regular clinical use is to promote the excretion of an iron overload, when phlebotomy is harmful, and the dosage varies between 2-10 g/d. In conditions where deferroxamine is used to prevent the iron-driven oxygen toxicity, i.e., acute or chronic inflammatory diseases with oxidative stress, the dosage can be extremely reduced and the addition of antioxidants could be useful.
Asunto(s)
Hierro/metabolismo , Estrés Oxidativo/fisiología , Antioxidantes/uso terapéutico , Deferoxamina/uso terapéutico , Quimioterapia Combinada , Radicales Libres/metabolismo , Homeostasis , Humanos , Peróxido de Hidrógeno/metabolismo , Quelantes del Hierro/uso terapéutico , Sobrecarga de Hierro/tratamiento farmacológico , Superóxidos/metabolismoRESUMEN
OBJECTIVE: To determine if asymptomatic stable chronic hyperlactatemia in human immunodeficiency virus (HIV)-infected patients under highly active antiretroviral therapy (HAART, including nucleoside analog reverse transcriptase inhibitors (NRTI)) could be improved by antioxidant supplementation. DESIGN: To match two groups of patients taking NRTI for at least 24 months: 15 without and 15 with antioxidant supplementation (vitamin E, beta-carotene, N-acetylcysteine, selenium, Gingko biloba extracts and nutritional supplements). For both the groups, the supplementation by antioxidants or its lack was carefully assessed. Venous lactatemia, blood oxidative stress markers (plasma lipid peroxidation, enzymatic and non-enzymatic antioxidants), CDC revisited classification, CD4 count and viral load, NRTI (with or without stavudine) and other antiretroviral drugs used, lipoatrophy, central fat accumulation were assessed. RESULTS: Patients were not statistically different with respect to the CDC classification, CD4 count, viral load and characteristics of antiretroviral therapy. Blood oxidative stress markers, i.e. vitamin E, vitamin A and beta-carotene tended to be higher in the supplemented group. The difference observed in venous lactate concentration between the two groups was significant (1.37 +/- 0.10 vs. 1.82 +/- 0.19 mmol/l in the supplemented and non-supplemented groups, respectively P = 0.04). CONCLUSION: Antioxidant supplementation improves the asymptomatic stable chronic hyperlactatemia observed in HIV-infected patients taking HAART including NRTI for a long time. Controlled studies are needed to demonstrate the efficacy of this supplementation on mitochondrial toxicity observed during HAART and the possible usefulness of its combination with mitochondrial cofactors like carnitine, riboflavine, coenzyme Q, alpha-lipoic acid.
Asunto(s)
Antioxidantes/uso terapéutico , Terapia Antirretroviral Altamente Activa/efectos adversos , Lactatos/sangre , Tejido Adiposo/patología , Adolescente , Adulto , Anciano , Fármacos Anti-VIH/efectos adversos , Fármacos Anti-VIH/uso terapéutico , Antioxidantes/metabolismo , Atrofia , Recuento de Linfocito CD4 , Suplementos Dietéticos , Femenino , Infecciones por VIH/complicaciones , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/virología , Humanos , Peroxidación de Lípido/efectos de los fármacos , Masculino , Persona de Mediana Edad , Estrés Oxidativo/efectos de los fármacos , Estudios Retrospectivos , Inhibidores de la Transcriptasa Inversa/uso terapéutico , Estavudina/efectos adversos , Estavudina/uso terapéutico , Carga ViralRESUMEN
A number of experimental models have shown abnormally high concentrations of cytotoxic oxygen derived free radicals (FR), and decreased concentrations of protecting anti-oxidising enzymes during myocardial ischaemia. These FR react with the unsaturated lipids of the cell membrane, a phenomenon known as membrane lipidoperoxidation (MLP) to produce very cytotoxic endoperoxides. We studied an intermediary product of MLP, malondialdehyde (MDA) in 10 patients with a preinfarction syndrome (Group 1) and 8 patients in the acute phase of myocardial infarction (Group 2). Plasma MDA was measured on admission (P2) and 12th day (P3). There was a significant elevation of MDA in both groups at P1 and P2 (p less than 0.01) compared with results obtained in 15 normal control subjects of the same age. The MDA concentration on the 12th day in the infarct group was significantly lower (189 +/- 41 ng/ml, p less than 0.01) compared with the highest value observed either on admission or on the 5th day (peak MDA 258 +/- 62 ng/ml). The difference between MDA concentrations on the 12th day and peak MDA was less striking in Group 1. None of the patients in Group 2 had a recurrence of chest pain after the initial phase of infarction and the residuals MDA concentration (P3) was similar to control values (181 +/- 27 ng/ml). On the other hand, in the preinfarction syndrome group, 4 patients had persistent unstable angina on the 12th day and their MDA concentrations remained high (250 +/- 42 ng/ml). This was interpreted as reflecting continuing MLP in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Enfermedad Coronaria/sangre , Anciano , Colesterol/sangre , Femenino , Radicales Libres , Humanos , Masculino , Malondialdehído/sangre , Persona de Mediana Edad , Infarto del Miocardio/sangre , Oxidación-Reducción , Triglicéridos/sangreRESUMEN
Delta coinfection or superinfection in a patient with chronic hepatitis B is characterized by a very transient delta antigenemia and an early seroconversion of IgM to IgG anti-delta. The persistent expression of delta antigen in the liver can be associated with acute, severe, or chronic hepatitis. In our two patients, delta antigenemia persisted respectively 10 weeks and 14 months with aggravation of liver histopathologic lesions without seroconversion. Such a serologic profile during delta infection does not seem to have been reported previously. These two cases concerned two patients with an important immunosuppression, one by a major immunosuppressive therapy and HIV superinfection, the other by an acquired immunodeficiency syndrome. The cytotoxic effect of delta virus in such circumstances is discussed.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/inmunología , Antígenos Virales/análisis , Anticuerpos Antihepatitis/análisis , Virus de la Hepatitis Delta/inmunología , Adulto , Seropositividad para VIH/inmunología , Antígenos de Hepatitis delta , Humanos , Masculino , Persona de Mediana Edad , Factores de TiempoRESUMEN
Nailfold capillary microscopy patterns in 100 patients aged more than 65 years and free from inflammatory diseases were compared to those of 100 young healthy adults. A higher prevalence of arteriovenous sludge (36% vs 7%, p less than 10(-6)), increase in capillary loop length (12% vs. 0%, p less than 10(-3)) and especially prominent subpapillary plexus (63% vs 12%, p less than 10(-9)) was found in the geriatric group. Such capillary patterns cannot be considered as abnormal in patients aged more than 65 years. Enlargement of capillary loops and loss of capillaries were never encountered. Bushy capillary formations and hemorrhages were very uncommon in both groups.
Asunto(s)
Uñas/irrigación sanguínea , Adulto , Anciano , Anciano de 80 o más Años , Capilares , Femenino , Humanos , Masculino , Microcirculación , Persona de Mediana EdadRESUMEN
The authors report the case of a 48 years old man presenting a pancreatic islet cell carcinoma (gastrinoma) with liver, nodes and peritoneal metastases, associated with an elevated alpha-fetoprotein (AFP) concentration. Incomplete remission was first obtained with a chemotherapy using Streptozotocin combined with 5-Fluorouracil, in association with a Somatostatin analogue (SMS 201-995). But when relapses occur, another chemotherapy was not so effective. Serum gastrin and AFP levels had the same evolution and appear to have the same interest to follow the course of the disease.
Asunto(s)
Gastrinoma/sangre , Gastrinoma/secundario , Neoplasias Hepáticas/sangre , Neoplasias Hepáticas/secundario , Neoplasias Pancreáticas/patología , Neoplasias Peritoneales/sangre , Neoplasias Peritoneales/secundario , alfa-Fetoproteínas/análisis , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Biopsia , Resultado Fatal , Fluorouracilo/administración & dosificación , Gastrinoma/tratamiento farmacológico , Gastrinas/sangre , Humanos , Neoplasias Hepáticas/tratamiento farmacológico , Metástasis Linfática , Masculino , Persona de Mediana Edad , Octreótido/administración & dosificación , Neoplasias Peritoneales/tratamiento farmacológico , Inducción de Remisión , Estreptozocina/administración & dosificaciónRESUMEN
Oxygen free radicals are used as a weapon by neutrophil morphopolynuclear cells, monocytes and macrophages against bacterial attacks. They do interact with arachidonic acid cascade catabolism that means they stimulate too, platelet cells and endothelial cells activity (EDRF is indeed "NO"). They prime all along inflammatory process and thrombosis which are main items of the pathology of vessels.
Asunto(s)
Radicales Libres/metabolismo , Enfermedades Vasculares/etiología , Hemostasis/fisiología , Humanos , Inflamación/etiología , Inflamación/fisiopatología , Oxidación-Reducción , Trombosis/etiología , Trombosis/fisiopatología , Enfermedades Vasculares/sangre , Enfermedades Vasculares/fisiopatologíaRESUMEN
Myocardial ischemia is accompanied by a release of free radicals (FR) derived from oxygen, elements having an important cytotoxic activity. These FR react with unsaturated lipids from the membrane fatty acids, leading possibly to a lysis of the membrane. This lipidic peroxidation of the fatty acids generates, in fact, endoperoxides, unstable lipid by-products and also with a cytotoxic activity. At the end of these reactions, cyclical compound and aldehydes are formed, and it is possible to titrate one of them, the malondialdehyde (MDA) which represents a marker of the aggression of the radicals on the membranes. We have therefore studied the appearance of MDA in the systemic venous blood and compared 10 patients with a threat syndrome (group I) to 8 other patients with acute myocardial infarction (group II). The plasma MDA level is measured upon admission (D1), on the 5th day (D2) and on the 12th day (D3) of the evolution. We have therefore found a significant elevation of MDA in the two groups of patients at D1 and D2, in comparison with the results obtained in a reference group of 15 normal patients (p less than 0.01). In the infarction group, the level of MDA on the 12th day (189 +/- 41 ng/ml) drops significantly as compared to the highest level noted upon admission and on the 5th day, called MDA peak (258 +/- 62 ng/ml, p less than 0.01). The MDA drop is less marked in group I of the threat syndromes.(ABSTRACT TRUNCATED AT 250 WORDS)
Asunto(s)
Peróxidos Lipídicos/metabolismo , Malonatos/sangre , Malondialdehído/sangre , Infarto del Miocardio/metabolismo , Anciano , Angina de Pecho/metabolismo , Creatina Quinasa/sangre , Radicales Libres , Humanos , Persona de Mediana EdadRESUMEN
The demonstration that lipid peroxidation (enzymatic or non enzymatic oxidation of polyunsaturated fatty acids) is involved and plays a pathophysiological role (in relation to the metabolic pathways of prostaglandins, leukotrienes and to others inflammation-related events) in the initiation of arteriosclerotic plaques is a breakthrough in the pathogenesis of atheroma. Macrophages play a central role in this mechanism. Indeed foam cells are macrophages loaded with oxidized low density lipoproteins (LDL). These oxidized LDL are preferentially recognized by macrophages thanks to their scavenger receptor. The role of such foam cells in the initiation and development of atheroma is well known. The formation of arteriosclerotic plaques results in important endothelial alterations, and endothelial cells lose their protective ability to prevent platelet aggregation and related thrombotic events. Inflammation and thrombosis are overlapping phenomena which are mediated by common cells (platelets, polymorphonuclear leucocytes, monocytes, macrophages, endothelial cells). During the activation of such inflammatory cells a number of eicosanoids are produced, and the profile of such metabolites is largely controlled by cellular interactions. In addition these inflammatory cells have the ability to produce oxygen free radicals, and initiate non enzymatic lipid peroxidation.
Asunto(s)
Arteriosclerosis/etiología , Peroxidación de Lípido , Lipoproteínas LDL/metabolismo , Arteriosclerosis/patología , Endotelio Vascular/patología , Humanos , Macrófagos/fisiología , Adhesividad Plaquetaria , Agregación Plaquetaria , Tromboxano A2/biosíntesisRESUMEN
NEURON DEATH: Major progress in our understanding of the pathophysiology of neurodegenerative diseases has greatly benefited from the convergence between work devoted to reactive oxygen species (including nitric oxide) and programmed cell death, or apoptosis, and exitotoxicity. LATERAL AMYOTROPHIC SCLEROSIS: The discovery of a mutation in the copper-zinc superoxide dismutase gene in patients with lateral amyotrophic sclerosis has made it possible to analyze the events leading to neuron death in transgenic mice. An overload of reactive oxygen species accelerates apoptosis and oxidative stress is implicated in excitotoxicity which is a hyperstimulation of excitatory amino acides (glutamate, aspartate) producing neuron death. OTHER CHRONIC CONDITIONS: Based on evidence from the mouse model, apoptosis, excitotoxicity and oxygenated free radicals could play a causal role in other neurodegenerative diseases including HIV-related encephalopathy, Parkinsonís disease and Alzheimerís disease.
Asunto(s)
Complejo SIDA Demencia/etiología , Esclerosis Amiotrófica Lateral/etiología , Apoptosis , Enfermedades Neurodegenerativas/etiología , Especies Reactivas de Oxígeno/metabolismo , Complejo SIDA Demencia/metabolismo , Esclerosis Amiotrófica Lateral/metabolismo , Animales , Modelos Animales de Enfermedad , Humanos , RatonesRESUMEN
Malondialdehyde is a marker for the oxidation of membrane unsaturated fatty acids. This biochemical process, called lipid peroxidation, occurs in the biosynthesis of leukotrienes, prostaglandins and other cytotoxic and chemotactic lipid peroxides. It may play a part in the genesis of atheroma from lipids stored in the arterial wall. Plasma malondialdehyde levels were found to be different in hyperlipidemic subjects with or without arterial lesions, and in rabbits under an atherogenic diet with or without added silicon. The same positive correlation was found in rabbit aorta between atheromatous lesions and high levels of malondialdehyde. These data would support the hypothesis that lipid peroxidation plays a role in atherogenesis.
Asunto(s)
Arteriosclerosis/metabolismo , Peróxidos Lipídicos/biosíntesis , Malonatos/análisis , Malondialdehído/análisis , Animales , Aorta/análisis , Arteriosclerosis/etiología , Colesterol/sangre , Modelos Animales de Enfermedad , Radicales Libres , Humanos , Hiperlipidemias/metabolismo , Malondialdehído/sangre , Conejos , Triglicéridos/sangreRESUMEN
Lipid peroxidation results from the attack of membrane phospholipids by free radicals derived from oxygen. It plays a major role in normal cell life processes. Under physiological conditions, this attack is modulated by an enzymatic system (superoxide dismutase, catalase, glutathione peroxidase) and by a non-enzymatic system (vitamin E and others). Many pathological processes might be explained by a deficient protection system or by an imbalance between attack and protection. Lipid peroxidation is difficult to detect and measure, and the methods available still have low sensitivity.
Asunto(s)
Peróxidos Lipídicos/fisiología , Oxígeno/metabolismo , Fosfolípidos/metabolismo , Animales , Radicales Libres , Humanos , Peróxidos Lipídicos/metabolismo , Lípidos de la Membrana/metabolismo , Oxígeno/fisiologíaRESUMEN
OBJECTIVES: Determine the oxidative stress status and its significance in elderly subjects. METHODS: Six parameters marking oxidative stress evaluated in 52 elderly patients (mean age 85 +/- 6 years; range 74 to 98) admitted to a medium-term and long-term nursing home (n = 30) or a hospital ward (n = 22) were compared with those in 30 disease-free young subjects (age range 20-40 years). Plasma levels of thiobarbituric acid reactive substances vitamin E and selenium and activity of free-radical protective enzymes (erythrocyte superoxide dismutase, plasma and erythrocyte glutathione peroxidase) were assessed. RESULTS: Thiobarbituric acid reactive substances were higher and superoxide dismutase, erythrocyte and plasma glutathione peroxidase, and plasma selenium were lower in elderly patients than in young controls. There was no difference in vitamin E levels. In the nursing home population, erythrocyte superoxide dismutase was correlated with erythrocyte glutathione peroxidase and vitamin E, plasma glutathione peroxidase with erythrocyte glutathione peroxidase, vitamin E and selenium and erythrocyte g peroxidase, vitamin E and selenium and erythrocyte glutathione peroxidase with vitamin E. Only the correlation between erythrocyte and plasma glutathione peroxidase was found in the hospitalized population. These levels remained unchanged for a 30 day period in individual patients. CONCLUSION: "Oxidative stress" assessed by six parameters was thus observed in the elderly population and could be considered as a "biological marker of ageing". Supplementation with selenium or other anti-oxidants could be proposed.
Asunto(s)
Envejecimiento/fisiología , Glutatión Peroxidasa/sangre , Estrés Oxidativo/fisiología , Superóxido Dismutasa/sangre , Sustancias Reactivas al Ácido Tiobarbitúrico/análisis , Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Valores de Referencia , Selenio/sangre , Vitamina E/sangreRESUMEN
Malondialdehyde (MDA) as lipid peroxidation marker was studied in 27 patients with acute coronary insufficiency. Significantly elevated plasma levels as compared with controls were found in patients with myocardial necrosis and with preinfarction syndrome. No correlation was found between MDA and creatine phosphokinase, and a significant MDA decrease was observed at day 12: plasma MDA reached normal levels in the myocardial necrosis group. The MDA decrease was also significant in the preinfarction group, but the MDA level remained high in 4 patients with unstable angina. MDA is not a prognostic index. No correlation was found between MDA and plasma lipid levels or patients' ages. These data confirm that myocardial ischemia is associated with abnormal production of oxygen-derived free radicals which react with the membrane unsaturated fatty acids, resulting in toxic endoperoxides. This is thought to be one of the physio-pathological pathways which aggravate ischemic myocardial tissue damage.
Asunto(s)
Enfermedad Coronaria/metabolismo , Peróxidos Lipídicos/biosíntesis , Malonatos/sangre , Malondialdehído/sangre , Lípidos de la Membrana/metabolismo , Animales , Creatina Quinasa/sangre , Perros , Radicales Libres , Humanos , Oxígeno/metabolismo , Factores de TiempoRESUMEN
Among 29 seropositive subjects who had participated in the HIV 87 therapeutic trial (Mérieux laboratories), the oxidative stress was evaluated at 24 months in 16 treated with diethyldithiocarbamate (dithiocarb) and in 13 who had received the placebo. No significant difference was found between these two groups, whereas the existence of an oxidative stress has been confirmed in seropositive subjects compared with controls.
Asunto(s)
Ditiocarba/uso terapéutico , Glutatión Peroxidasa/sangre , Infecciones por VIH/metabolismo , Seropositividad para VIH/metabolismo , Malondialdehído/sangre , Vitamina E/sangre , Adulto , Método Doble Ciego , Femenino , Infecciones por VIH/tratamiento farmacológico , Humanos , Masculino , Placebos , Valores de Referencia , Selenio/sangre , Superóxido Dismutasa/sangreRESUMEN
The results of 20 months' activity of the anonymous and free-of-charge detection centre of the Pitié-Salpêtrière hospital group, Paris, concerning human immunodeficiency virus infection (HIV) are presented. During that period, 3,480 persons consulted and 3,332 anonymous questionnaires were filled and returned: 20.5 percent of the subjects were homosexuals, 6.5 percent were drug-addicts and 73 percent were non drug-addict heterosexuals; 31 percent used condoms. A total of 3,398 blood samples were collected; 232 sera were positive or undetermined for HIV-1 and/or HIV-2 by the ELISA method; 132 Western Blot tests confirmed the positivity for HIV-1 but not for HIV-2. The overall serum positivity was 4 percent; 18.3 percent of drug-addicts, 9.5 percent of homosexuals and 0.9 percent of heterosexuals were HIV positive. Among seropositive subjects, 51 percent were homosexuals, 27 percent were drug-addicts, 4 percent were homosexual drug-addicts and 18 percent were heterosexuals (43 percent of these had had multiple partners); condoms were used by 59 percent of HIV positive subjects. The percentage of HIV positive subjects in our series was lower than that estimated in populations at risk (drug-addicts 50 percent, homosexuals 32 percent); it was similar to the percentages found in other detection centres (5 to 6 percent). Most seropositive patients belong to the category of persons who are the first to be struck by HIV. The heterosexual population is relatively spared, but most of the recent seroconversions have occurred in this group.
Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/prevención & control , VIH-1 , VIH-2 , Síndrome de Inmunodeficiencia Adquirida/transmisión , Adolescente , Adulto , Anciano , Western Blotting , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Masculino , Tamizaje Masivo , Persona de Mediana Edad , Conservadores Farmacéuticos , Factores de Riesgo , Parejas Sexuales , Trastornos Relacionados con SustanciasRESUMEN
Free oxygen radicals (F.O.R.) belong to a very aggressive chemical species derived from molecular oxygen. Their role in inflammation is well established and Polymorphonuclear neutrophils (PMNS) make use of them as antibacterial weapons. Their role has been experimentally demonstrated in numerous ischemia-reperfusion models. Free radical scavengers such as the superoxide dismutase, allopurinol or desferrioxamine can prevent the occurrence of lesions. The essential role of PMNS in these models is demonstrated by the fact that previous depletion of the animal in PMNS also prevents such lesions. Histologically, in these ischemia-reperfusion models, PMNS infiltration may be quantified by assay of myeloperoxidase. In experimental models of inflammatory colitis (acetic acid, bacterial polysaccharides) intestinal wall infiltration by PMNS is a fundamental phenomenon and is also a characteristic of Crohn's disease and exacerbations of Ulcerative Colitis. Thus, it is probable in both disorders that F.O.R. play an important role since steroids inhibit their secretion by PMNS and 5-aminosalicylic acid has been shown to be a F.O.R. scavenger.