Serum Xanthine Oxidase Research Articles

Alterations in antioxidant status during neonatal sepsis.

Septicaemia is a major threat to survival during the early stages of life. There are several reports that suggest that reactive oxygen species (ROs) play a role in a wide variety of diseases. We estimated the activity of xanthine oxidase (XO), malondialdehyde (MDA) content, creatine phosphokinase (CPK) activity, activities of key enzymatic antioxidants, such as superoxide dismutase (SOD), glutathione peroxidase (GPx) and peroxidase (PO), and non-enzymatic antioxidants, viz. uric acid (UA) and albumin (ALB), in 30 neonates with sepsis and 20 age-matched controls. The babies were categorized as preterm/term, early onset/late onset, and shock/without shock, as per clinical and laboratory investigations. The study was carried out to evaluate the status of antioxidant enzymes and non-enzymatic antioxidants with a view to suggesting the introduction of antioxidant therapy in neonatal sepsis. The activities of serum XO, CPK, SOD and GPx, and the content of MDA were found to be significantly elevated in the neonates with sepsis when compared with controls. Conversely, the activity of PO and the levels of UA and ALB were decreased. The septic, full-term neonates registered significantly higher CPK activity (70%) than the preterm septic neonates. However, infants with late-onset and shock sepsis had a significant decrease in CPK activity (p < 0.05) compared with their corresponding sub-groups. Likewise, UA levels were found to be 28% depressed (p < 0.05) in the babies with late-onset sepsis and 51% increased (p < 0.001) in babies with shock compared with their respective sub-groups. Neonates with septic shock also registered a significant elevation in GPx activity (28%) compared with those without shock. This study suggests increased production of ROs in neonates with sepsis, as evidenced by the positive regulation of XO, SOD and GPx activity. The elevation of antioxidant enzymes, however, was not so effective as to protect from cellular damage and thereby result in higher MDA production. It is evident that antioxidant therapy might be useful in the management of neonates with sepsis but further detailed clinico-biochemical investigations are required to define effective antioxidant therapy.

Purine requirements for the expression of Cape buffalo serum trypanocidal activity

Cape buffalo serum contains xanthine oxidase which generates trypanocidal H 2O 2 during the catabolism of hypoxanthine and xanthine. The present studies show that xanthine oxidase-dependent trypanocidal activity in Cape buffalo serum was also elicited by purine nucleotides, nucleosides, and bases even though xanthine oxidase did not catabolize those purines. The paradox was explained in part, by the presence in serum of purine nucleoside phosphorylase and adenosine deaminase, that, together with xanthine oxidase, catabolized adenosine, inosine, hypoxanthine, and xanthine to uric acid yielding trypanocidal H 2O 2. In addition, purine catabolism by trypanosomes provided substrates for serum xanthine oxidase and was implicated in the triggering of xanthine oxidase-dependent trypanocidal activity by purines that were not directly catabolized to uric acid in Cape buffalo serum, namely guanosine, guanine, adenine monophosphate, guanosine diphosphate, adenosine 3′:5-cyclic monophosphate, and 1-methylinosine. The concentrations of guanosine and guanine that elicited xanthine oxidase-dependent trypanocidal activity were 30–270-fold lower than those of other purines requiring trypanosome-processing which suggests differential processing by the parasites.

Infection-associated decline of cape buffalo blood catalase augments serum trypanocidal activity.

Clearance of trypanosomes from the blood of infected Cape buffalo was associated with the development of two responses: (i) complement-dependent and clone-specific lytic activity and (ii) complement-independent trypanocidal activity that was not restricted by trypanosome clone or species. This latter activity was mediated by H2O2 and required the presence of xanthine oxidase in serum but not the addition of purine substrates. Expression of the xanthine oxidase-dependent trypanocidal activity in Cape buffalo serum was coincident with, and required, a decline in its H2O2 catabolic activity. The H2O2 catabolic activity of Cape buffalo serum was due solely to catalase and declined by eightfold around the time that trypanosomes were cleared from the blood, accompanied by a fivefold drop in erythrocyte-associated catalase activity. The Cape buffalo did not develop subsequent parasitemic waves. Clearance of parasitemia in similarly infected cattle was also associated with development of trypanosome clone-specific lytic activity, but not with the acquisition of H2O2-dependent trypanocidal activity in serum, and the cattle supported recurring parasitemia. The lack of trypanocidal activity in pre- and postinfection cattle sera was due to their low content of xanthine oxidase and sustained catalase activity. These data strongly suggest that an infection-induced serum oxidative response, the efficacy of which is amplified by a decline in blood catalase, contributes to suppression of recurring parasitemia in Cape buffalo.

Determination of xanthine oxidase in human serum by a competitive enzyme-linked immunosorbent assay (ELISA)

Xanthine oxidase was purified from human milk and used to immunise rabbits. A competitive immunoenzymatic assay with purified enzyme and rabbit antiserum was optimised to measure xanthine oxidase in human serum, the lowest detectable amount being 0.03 pmol of enzymatic protein. Thus, the test (i) is sensitive enough to determine xanthine oxidase in human serum, being more sensitive than the spectrophotometric method, (ii) it is more convenient for clinical laboratories than other sensitive tests and (iii) it has the advantage over the enzyme activity-based assays of also detecting inactive enzyme molecules. A competitive enzyme-linked immunosorbent assay (ELISA) was used to measure the serum xanthine oxidase level in healthy donors and in patients with liver diseases, and it was found that any concentration below 1 mg/L is in the normal range.

Hepatotoxicity of ricin, saporin or a saporin immunotoxin: xanthine oxidase activity in rat liver and blood serum

Male Wistar rats each received an i.p injection of the ribosome-inactivating proteins ricin or saporin, or a Ber-H2 (anti-CD30)-saporin immunotoxin at a dose corresponding to three times the LD50 calculated for mice. Animals were killed 24, 48 or 72 h after treatment. Histological examination showed hepatic necrosis in all treated animals, although the sinusoidal lining was affected only in ricin-poisoned rats. The activities of xanthine dehydrogenase (D-form) and oxidase (O-form) were determined spectrophotometrically in liver and serum samples. In ricin-treated animals the liver enzyme was progressively converted from the D- to the O-form, which accounted for more than 60% of total activity after 48 h of poisoning, whilst no change in the xanthine oxidase activity was found in the serum. In the liver of rats treated with free or Ber-H2-conjugated saporin, the D-form was more than 75%, as in normal animals. In the same animals the serum xanthine oxidase activity was up to three-fold control values. The determination of serum xanthine oxidase may prove helpful in the evaluation of liver damage in patients treated with immunotoxins. It may become a diagnostic tool for the differential diagnosis of liver diseases.

Changes in body fluid markers in intestinal ischemia

New Zealand rabbits were assigned randomly to three groups: sham operation, intestinal simple obstruction, and strangulation obstruction. To relate possible changes in the body fluid content of biochemical markers to the strangulation process, subsequent samples of blood and peritoneal fluid, for the determination of levels of creatine kinase (CK), lactic acid (LA), xanthine oxidase (XO), and inorganic phosphate (IP), were obtained at 1-, 2-, 4-, and 6-hour intervals, and intestinal histological specimens were graded blindly. Significant increases in plasma LA (3.93 ± 0.26 v 2.99 ± 0.37; P < .05), peritoneal LA (5.03 ± 1.14 v 3.33 ± 0.86; P < .05), and CK (940 ± 146 v 772 ± 165, P < .05) occurred after 1 hour of ischemic injury. Except for serum CK, all parameters in the blood and peritoneal fluid in group 3 were markedly elevated within 4 hours. The serum CK remained almost unchanged throughout the 6-hour study period. The results suggest that plasma LA, peritoneal LA, and CK are sensitive indicators in the early diagnosis of bowel ischemia; the determination of both serum and peritoneal XO and IP was also helpful for early diagnosis; in contrast, serum CK was not a useful indicator. The value of any biochemical marker as an early diagnostic tool for intestinal ischemia depends not only on its quantity but also on its location and mechanism of release.

Xanthine oxidase contributes to lung leak in rats subjected to skin burn.

We found that rats subjected to thermal skin injury (skin burn) had increased serum xanthine oxidase (XO) activities, increased serum complement activation (decreased serum CH50 levels), increased erythrocyte (RBC) fragility, increased lung neutrophil accumulation, and increased lung leak compared to sham-treated rats. Treatment of rats with allopurinol (an XO inhibitor) not only decreased serum XO activity, but also decreased complement activation, RBC fragility, lung neutrophil accumulation, and lung leak abnormalities in rats subjected to skin burn. We conclude that XO may contribute to acute lung injury and a number of events associated with the development of acute lung leak following skin burn.

Xanthinoxidase und Sulfhydrylgruppen und die antirheumatische Wirkung des Xanthinoxidase-Hemmers Allopurinol im Tiermodell der Kollagen(II)-Arthritis

Xanthine oxidase (XOD) was present in sera of patients with inflammatory and autoimmune rheumatic diseases in up to 50-fold higher levels (p<0.001) than in sera from healthy donors and patients with nonrheumatic diseases including internal diseases, AIDS and carcinoma of different organs. In addition, serum sulfhydryls (SH) were determined as sensitive markers of oxidative stress. The SH status in patients with rheumatic diseases was diminished by 45-75% (p <0.001) and inversely correlated to the concentration of serum XOD (r = 0.73), suggesting a causal interrelation. The depletion of serum sulfhydryls by the oxyradical- producing XOD/acetaldehyde system was mimicked successfully ex vivo in human serum from healthy donors. Cortisone treatment of patients with elevated levels of XOD caused a prompt normalization of elevated XOD levels.

Mechanisms of Interleukin-2-Induced Hydrothoraxy in Mice

Interleukin (IL)-2 is known to induce vascular leak syndrome (VLS), which was suggested to be mediated by immune system-derived cytokines, including tumor necrosis factor (TNF). To characterize the role of TNF in IL-2 toxicity in C3H/HeN mice, we used two approaches to downregulate TNF production in vivo: treatment with dexamethasone (DEX) and induction of endotoxin (lipopolysaccharide) (LPS) tolerance by a 4-day pretreatment with LPS (35 micrograms/mouse/day). Mice were then treated with IL-2 for 5 days (1.8 x 10(5) IU/mouse, twice daily). Both DEX and LPS tolerance blocked development of hydrothorax in IL-2-treated mice and inhibited TNF induction. DEX and LPS tolerance also ameliorated IL-2 toxicity in terms of decrease in food intake and inhibited the increase of the acute-phase protein, serum amyloid A (SAA). The IL-2 activation of splenic natural killer (NK) cell activity was also diminished by DEX and, to a lesser extent, by LPS-tolerance. Treatment with IL-2 also caused induction of the superoxide-generating enzyme xanthine oxidase (XO) in tissues and serum and induced bacterial translocation in the mesenteric lymph nodes (MLN). These data suggest that multiple mechanisms, including NK cell activity, cytokines, and reactive oxygen intermediates, might be important in the vascular toxicity of IL-2.

Effects of FK506, an immunosuppressive agent, on genesis of water-immersion stress-induced gastric lesions in rats.

We examined the effects of FK506, an immunosuppressive agent, on the genesis of water immersion stress-induced gastric lesions in rats. Using high-performance liquid chromatography, four kinds of prostaglandins, ie, 6-keto-prostaglandin F1 alpha, prostaglandin F2 alpha, prostaglandin E2, and prostaglandin D2, were detected, and no leukotrienes were detected in gastric mucosa in rats without stress. After 6 hr of stress, gastric lesions developed with decreases in all prostaglandin contents, and the emergence of peptide leukotrienes was observed. Intramuscular administration of FK506 (0.1, 0.25, 0.5, 1.0, and 2.0 mg/kg) reduced lesion index dose-dependently. Administration of FK506 at doses over 0.25 mg/kg decreased all prostaglandin contents, but did not affect the increase in leukotriene contents. Pretreatment with famotidine or omeprazole reduced lesion index, and the protective effects were equivalent to those of 1.0 mg/kg of FK506, although FK506 did not affect gastric secretion during water-immersion stress. Water-immersion stress did not change the activities of xanthine oxidase in either stomach or serum. Polyoxyethylene-modified superoxide dismutase did not prevent gastric lesions. Water-immersion stress significantly increased myeloperoxidase activity in gastric mucosa, and FK506 reduced the increase in myeloperoxidase activity induced by stress. From our results, other factors besides gastric acid secretion and tissue eicosanoid contents, such as chemoattractant factor, might also be involved in the genesis of water-immersion stress-induced gastric lesions in rats.

Effects of allopurinol on endotoxin-induced increase in serum xanthine oxidase in the horse

Using a modified bovine milk enzyme kinetic assay, xanthine oxidase activity of serum collected from 34 adult, healthy horses of both sexes was determined. Enzyme activity varied from 0 to 126 mU litre-1 with a mean of 44.95 +/- 21.05 mU litre-1. The optimal pH and temperature for maximal activity were 7.8 and 28 degrees C, respectively. Freezing the serum for four days at -70 degrees C did not destroy the enzyme activity. Various doses (25, 50 and 75 micrograms kg-1, intraperitoneally) of endotoxin (lipopolysaccharide D1 Escherichia coli O26:B6) previously known to have caused moderate to severe systemic clinical signs of endotoxaemia in horses produced a significant dose related increase in serum xanthine oxidase activity. Pretreatment (12 hours) with allopurinol (5 and 50 mg kg-1, intravenously [corrected]) significantly reduced the rise in xanthine oxidase activity in endotoxin (50 micrograms kg-1, intraperitoneally) treated horses. The results of this study suggest that xanthine oxidase catalysed production of superoxide radicals may play a role in the pathogenesis of endotoxaemia and that allopurinol, an alternate substrate, should be further evaluated for its therapeutic potential in endotoxin related systemic diseases in horses.

Spectrophotometric assay of xanthine oxidase with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulphonate) (ABTS) as chromogen

A new method for the determination of xanthine oxidase activity, based on the oxidation of 2, 2'-azino-di(3-ethylbenzthiazoline-6-sulphonate) (ABTS) by use of uricase and peroxidase, is described. The absorbance increase of the oxidized form of ABTS, measured after 10 min at 410 nm is proportional to xanthine oxidase activity. The method is sensitive, precise (CV below 8.3%), and linear up to 20 U/l. The analytical recovery of the ABTS-method was quantitative. Comparison with the UV and colorimetric NBT-method gave good correlation ( r ⩾ 0.984). Reference values for serum xanthine oxidase activities determined with the new ABTS-method on 83 healthy persons are 0 to 1.20 U/l.

Enhanced xanthine oxidase activity in mice treated with interferon and interferon inducers

Administration to mice of either interferon (IFN) or IFN inducers resulted in a marked increase of xanthine oxidase (XO) activity in different organs. Dose response studies revealed that serum XO was increased by administration of polyinosylic-polycyticylic acid (poly I-C) at doses as low as 0.1 mg/kg. In view of the well known ability of XO to generate superoxide radicals it is suggested that its induction might play a role in several biological effects of IFN.

Xanthine oxidase in serum of viral hepatitis patients may interfere in urate determination by endpoint measurement with xanthine in the reagent mixture.

Xanthine oxidase in serum of viral hepatitis patients may interfere in urate determination by endpoint measurement with xanthine in the reagent mixture.

Human serum xanthine oxidase: Fluorometric assay applicable to the investigation of liver disorders

1. 1. A fluorometric assay for serum xanthine oxidase activity that could be used as a back-up to current tests in the differential diagnosis of acute liver damage is described. 2. 2. High levels of serum xanthine oxidase activity were found in acute liver damage. Values were low in other liver or non-liver diseases.

Serum xanthine oxidase in bladder carcinoma.

This study comprises of 48 normal men as control group and 49 patients with various stages of bladder carcinoma. Serum xanthine oxidase and uric acid levels were determined. Assessment in terms of changes of the enzyme xanthine oxidase was carried out prior and after surgery as a short-term follow-up. There was a significant fall of serum xanthine oxidase in patients with bladder carcinoma; it also varied with the stage of cancer.

Elevation of serum xanthine oxidase activity following halothane anesthesia in man.

Halothane, but not methoxyflurane, was found to cause specific hepatocellular damage, the hepatotoxicity being prompt but transient. The hepatotoxicity was demonstrated by the elevation in the serum activity of xanthine oxidase, a highly sensitive marker for acute liver damage.

Elevation of serum xanthine oxidase following halothane anesthesia in the rat.

Halothan anesthesia was found to be hapatotoxic in the rat, as demonstrated by a significant elevation of serum xanthine oxidase (SXO) level. SXO appeared to be more sensitive marker of liver damage than serum glutamic oxalacetic transaminase. SXO was found to be elevated also following exposure to relative hypoxia.

Serum xanthine oxidase in jaundice

Serum xanthine oxidase activity was measured by a radiochemical method in 137 consecutive patients with jaundice of varying etiology and in 40 non-jaundiced patients with liver or other disease. Serum xanthine oxidase was markedly increased, up to 50 times the upper normal limit (mean + 2 S.D.), in 32 out of 34 patients with infectious hepatitis. A slight elevation of serum xanthine oxidase, up to twice the upper normal limit, was found in 2 out of 49 patients with extrahepatic obstructive jaundice and in 4 out of 20 patients with chronic renal failure. In comparison to serum glutamic-oxaloacetic transaminase and lactate dehydrogenase serum xanthine oxidase appeared to be the more sensitive and specific indicator of acute hepatocellular damage.

Serum xanthine oxidase. An experience with 2000 patients.

Serum xanthine oxidase (SeXO) determination was performed on the sera of 2000 patients. SeXO elevations of 10 international milliunits (ImU) and above were noted only in acute liver disease. In viral hepatitis or toxic liver injury the magnitude of elevations of SeXO to the upper limit of normal is 50 times greater than the magnitude of elevation of the transaminases above normal. The enzyme level in obstructive or hemolytic jaundice remains normal or slightly elevated, not exceeding 10 lmU/liter. For this reason serum xanthine oxidase determination is valuable in differentiating jaundice due to acute liver disease from that due to obstructive jaundice or hemolysis, as there is almost no overlap in the enzyme values. On the other hand, SeXO determination had no diagnostic or prognostic value in liver cirrhosis, amebic abscess, or hydatid cyst of liver. Significant elevations of SeXO were noted in infectious mononucleosis but in none of the other viral infections studied.