Vitamin E supplementation fails to impact measures of oxidative stress or the anaemia of feline chronic kidney disease: a randomised, double-blinded placebo control study.

This study was designed to test the hypothesis that supplementation with vitamin E, an antioxidant, in cats with chronic kidney disease (CKD), would reduce oxidative stress and its impact on RBC membrane fragility, resulting in these cats maintaining a greater packed cell volume (PCV) compared with CKD cats not receiving supplementation. Thirty-six cats with CKD were randomly assigned to receive either daily vitamin E or a placebo for 3 months in a double-blinded study design. History and physical examination, blood pressure, complete blood count (CBC), PCV, biochemical profile and urinalysis (UA) were determined. Parameters of oxidative stress and osmotic fragility were measured. Cats were administered vitamin E or placebo once daily for 3 months. Cats were then reassessed and the diagnostics were repeated. Twenty-four cats completed the study, 11 in the vitamin E group and 13 in the placebo group. There were no significant differences between the two groups at the start, or upon completion of the study with regard to biochemical parameters, oxidative stress, erythrocyte osmotic fragility or PCV. None of these parameters changed significantly in either group over the treatment period. Daily supplementation with 30 IU of vitamin E did not affect the measures of oxidative stress or the anaemia seen in cats with CKD.

Assessment of oxidative stress in leukocytes and granulocyte function following oral administration of a silibinin-phosphatidylcholine complex in cats.

OBJECTIVE: To determine the effect of oral administration of a silibinin-phosphatidylcholine complex (SPC) on oxidative stress in leukocytes and granulocyte function in healthy cats. ANIMALS: 10 purpose-bred adult cats. PROCEDURES: Cats were administered SPC (10 mg/kg/d) orally for 5 days; blood samples were collected prior to and immediately after the 5-day treatment period. Leukocytes were incubated with monochlorobimane for detection of reduced glutathione (GSH) via flow cytometry. Leukocytes were also incubated with dihydrorhodamine 123 and mixed with Escherichia coli conjugated to a fluorescent marker to measure E coli phagocytosis and the subsequent oxidative burst via flow cytometry. Activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase, along with the reduced glutathione-to-oxidized glutathione (GSH:GSSG) ratio and a measure of lipid peroxidation (malondialdehyde concentration [micromol/L of blood]), were measured spectrophotometrically. RESULTS: The mean fluorescence intensity (MFI), representing GSH content, increased significantly in feline lymphocytes and granulocytes following 5 days of oral administration of SPC. Mean +/- SD lymphocyte MFI significantly increased from 27.8 +/- 9.0 to 39.6 +/- 6.7, and the granulocyte MFI increased from 508.6 +/- 135.6 to 612.1 +/- 122.9. Following 5 days of SPC administration, the percentage of phagocytic cells that were responding optimally significantly increased (from 37 +/- 11.8% to 45 +/- 17.5%). Other measures of oxidative stress did not change significantly. CONCLUSIONS AND CLINICAL RELEVANCE: In cats, oral administration of supplemental SPC appears to increase granulocyte GSH content and phagocytic function, both of which would be potentially beneficial in cats with diseases associated with oxidative stress.

Oxidative stress and innate immunity in feline patients with diabetes mellitus: the role of nutrition.

This study was undertaken to test the hypothesis that oxidative stress is increased and neutrophil function is decreased in cats with diabetes mellitus (DM). Measures of oxidative stress and neutrophil function were evaluated in 20 control and 15 diabetic cats. Cats were then fed a diet designed specifically for feline diabetics (Purina DM Dietetic Management Feline Formula) for 8 weeks, after which all assays were repeated. Cats with DM had significantly less plasma superoxide dismutase (SOD) than control cats, consistent with a greater degree of oxidative stress in the DM group. Following 8 weeks of consuming a diabetes-specific diet glutathione peroxidase, an antioxidant enzyme increased significantly in both groups. Other parameters of oxidative stress, as well as neutrophil function, were similar between groups and did not change following dietary intervention. The DM cats were significantly older and heavier than the control cats, which may have contributed to differences in parameters of oxidative stress and levels of antioxidant enzymes between these groups, but the decreased level of SOD enzyme in the diabetic group would appear to support the continued development of targeted antioxidant supplementation for this cats with this disease.

Effects of an oral superoxide dismutase enzyme supplementation on indices of oxidative stress, proviral load, and CD4:CD8 ratios in asymptomatic FIV-infected cats.

This study was designed to test the effect of antioxidant supplementation on feline immunodeficiency virus (FIV)-infected felines. Six acutely FIV-infected cats (> or =16 weeks post-inoculation) were given a propriety oral superoxide dismutase (SOD) supplement (Oxstrin; Nutramax Laboratories) for 30 days. Following supplementation, the erythrocyte SOD enzyme concentration was significantly greater in the supplemented FIV-infected group than the uninfected control group or the unsupplemented FIV-infected group. The CD4+ to CD8+ ratio increased significantly (0.66-0.88) in the SOD supplemented FIV-infected cats but not in the unsupplemented FIV-infected cats. Proviral load and reduced glutathione (GSH) levels in leukocyte cell types did not change significantly following supplementation. Antioxidant supplementation resulted in an increase in SOD levels, confirming the oral bioavailability of the compound in FIV-infected cats. This result warrants further investigation with trials of antioxidant therapy in FIV-infected cats that are showing clinical manifestations of their disease, as well as in other feline patients where oxidative stress likely contributes to disease pathogenesis, such as diabetes mellitus and chronic renal failure.