Effects of zinc supplementation on glycemic control and oxidative stress in experimental diabetes: A systematic review.

INTRODUCTION: Diabetes mellitus (DM), an important public health problem worldwide, can cause imbalances in the homeostasis of trace elements such as zinc (Zn). It is possible that an adequate nutritional status related to nutrients is essential for the normal functioning of antioxidant defense systems, and any change in the concentration of these substances could increase the chances of DM complications. OBJECTIVE: To present a review on the effect of zinc supplementation on glycemic control and oxidative stress in experimental diabetes. METHODS: This is a systematic review of articles that investigated the effects of zinc supplementation on glycemic control and oxidative stress in diabetic rats. The PICOS strategy was used for the development of the research question, and the Syrcle tool for the quality assessment of the studies included in the review. Articles available in the PubMed, Scopus, and Web of Science databases were included without restriction on year of publication. The Syrcle tool was used to assess the risk of bias of the included studies. RESULTS: Fifteen studies were included in the review, seven of which evaluated glycemic control and oxidative stress after zinc supplementation, five only oxidative stress and three only glycemic control after zinc treatment. In all the studies included, diabetes was induced by the administration of streptozotocin (STZ) at doses ranging from 40 to 100 mg/kg. Zinc supplementation was made in the diet or drinking water or by gavage or intraperitoneal injection. The most used doses were 100 mg/kg of body weight by gavage and 0.32 and 0.64 g/kg in diet. The supplementation period ranged from 14 days to 8 weeks. Six studies revealed that zinc supplementation decreased fasting blood glucose as well as insulin resistance; nine studies included in this review reported decreased MDA concentration; in five studies, there was an increase in the activity of antioxidant enzymes (GPx, SOD, GSH and catalase); and one of the studies reported a reduction in glycated hemoglobin. CONCLUSION: Zinc supplementation improved hyperglycemia and revealed a protective potential against oxidative stress associated with experimental diabetes.

Early metabolic reactivation versus antioxidant therapy after a traumatic spinal cord injury in adult rats.

Disability after traumatic spinal cord injury (TSCI) results from physical trauma and from "secondary mechanisms of injury" such as low metabolic energy levels, oxidative damage and lipid peroxidation. In order to prove if early metabolic reactivation is a better therapeutic option than antioxidant therapy in the acute phase of TSCI, spinal cord contusions were performed in adult rats using a well-characterized weight drop technique at thoracic 9 level. After TSCI, pyrophosphate of thiamine or non-degradable cocarboxylase (NDC) enzyme was used to maintain energy levels, antioxidants such as superoxide dismutase and catalase (ANT) were used to decrease oxidative damage and methylprednisolone (MP), which has both therapeutic properties, was used as a control. Rats were divided into one sham group and six with TSCI; one of them received no treatment, and the rest were treated with NDC, MP, NDC + MP, NDC + ANT or ANT. The ANT group decreased lactate and creatine phosphokinase levels and increased the amount of preserved tissue (morphometric analysis) as well as functional recovery (Basso, Beattie and Bresnahan or BBB motor scale). In contrast, NDC treatment increased lipid peroxidation, measured through thiobarbituric acid reactive substances (TBARS) levels, as well as spinal cord tissue destruction and functional deficit. Early metabolic reactivation after a TSCI may be deleterious, while natural early metabolic inhibition may not be a "secondary mechanism of injury" but a "secondary neuroprotective response". While increased antioxidant defence after a TSCI may currently be an ideal therapeutic strategy, the usefulness of metabolic reactivation should be tested in the sub-acute or chronic phases of TSCI and new strategies must continue to be tested for the early ones.

A double-blind, randomized trial of 0.05% betamethasone vs. topical catalase/dismutase superoxide in vitiligo.

BACKGROUND: Among all the topical immunomodulators, vitiligo's mainstay therapy includes topical corticosteroids. Many other non-immune theories have also been suggested for vitiligo's pathogenesis, but the role of oxidative stress has gained more importance in recent years. OBJECTIVE: To compare the effect of topical 0.05% betamethasone vs. catalase/dismutase superoxide (C/DSO). STUDY DESIGN: Randomized, matched-paired, double-blind trial. SETTING: Dermatology Section, University of Antioquia, Medellín, Colombia. SUBJECTS: Patients (aged > 18 years or between 12 and 18 years) with parent's informed consent, with stable or active bilateral vitiligo. INTERVENTION: Topical 0.05% betamethasone or C/DSO. METHODS: Two lesions similar to each other in size were chosen. All assessments were made by two blinded investigators, and photographs were subjected to morphometry analysis. MAIN OUTCOME: Skin repigmentation by digital morphometry. RESULTS: Twenty-five patients were enrolled in the study (21 women and 4 men). Mean age of participants was 40 years (range: 12-74 years). One patient on C/DSO experienced a mild local erythematous papular rash that self-resolved. At 4 months of therapy, there was no statistical difference on the percentage of repigmentation between betamethasone and C/DSO (5.63% +/- 27.9 vs. 3.22% +/- 25.8, respectively, P = 0.758). After 10 months of therapy, the percentage of skin repigmentation increased to 18.5 +/- 93.14% with betamethasone and to 12.4 +/- 59% with C/DSO, but again, we found no statistical differences (P = 0.79). DISCUSSION AND CONCLUSIONS: Few studies have described objective methods to evaluate repigmentation among vitiligo patients. Digital morphometry provides an objective assessment of repigmentation in vitiligo. Objective vitiligo repigmentation with topical C/DSO at 10 months is similar to topical 0.05% betamethasone. Although a mild adverse effect was related to the use of C/DSO, such finding was not severe enough to discontinue treatment.

Genotoxic effect of ozone in human peripheral blood leukocytes.

The genotoxic effect of ozone was studied in human leukocytes in vitro, using the single cell gel electrophoresis (SCGE) assay. Cell treatment for 1 h at 37 degrees C with 0.9-5.3 mM O(3) resulted in a dose-dependent increase of DNA damage, comparable to that induced by 4-40 mM of H(2)O(2), used as a positive control. This effect of ozone was reversed by post-treatment incubation of the cells for 45-90 min at 37 degrees C, and prevented by pre-incubation of the cells with catalase (20 microg/ml). These results demonstrate that O(3) induces DNA-damage in primary human leukocytes. The damage is rapidly repaired, and probably mediated by the formation of H(2)O(2).

Purification of catalase from human placenta

The therapeutic use of an antioxidant complex containing superoxide dismutase and catalase has been proposed for the treatment of several diseases in which reactive oxygen species have an important role. Although superoxide dismutase for human use is commercially available, methods for the production of catalase for human use have not been described. An industrial process was developed for the purification of catalase for human use as a by-product of albumin production from human placenta, comprising two parts: (1) albumin and catalase co-purification steps, including blood extraction from ground placentas, precipitation of haemoglobin with ethanol/chloroform, concentration/diafiltration by tangential filtration and anionic chromatography, by which non-adsorbed catalasewas separated from albumin; and (2) catalase purification steps after albumin separation, including a second anionic chromatography step and dye-affinitychromatography. This method provided a final recovery of 27% (70–100% in each step) with 670-fold purification of catalase (85%pure) and a specific activity of 49000 units/mg, which is higher than that of commerciallyavailable human catalase. This processpermits the co-purification of catalase and albumin and can easily be scaled up.

Efeitos do alopurinol sobre as alteraçöes morfológicas produzidas pela isquemia testicular temporária em ratos / Reperfusion injury with allopurinol after short term testicular ischemia in rats

O objetivo do presente estudo foi avaliar, em ratos, se o alopurinol é capaz de proteger o testículo contra os efeitos da isquemia com duraçäo de uma hora, seguida de reperfusäo. Dezoito ratos adultos, Wistar-EPM1, com peso variando entre 300 e 340g, foram divididos em três grupos: controle (G1), isquemia (G2) e isquemia com alopurinol (G3) com seis animais cada. Após anestesia com pentobarbital sódico intraperitoneal (30mg/Kg), o testículo esquerdo era exteriorizado e mantido imerso em soluçäo salina (0,9 por cento) à temperatura ambiente durante uma hora. Nos grupos G2 e G3 o pedículo era clampeado durante o experimento (1h). No grupo G3 cada animal recebeu 50 mg/Kg de alopurinol V.O. nos dois dias anteriores e duas horas antes da isquemia. Após 60 dias os animais foram anestesiados, sacrificados e os testículos removidos, pesados e preparados para exame histopatológico (HE). As lâminas foram analisadas de acordo com a classificaçäo de Cosentino. Observou-se diminuiçäo significante do peso do testículo esquerdo nos grupos G2 e G3 (p<0,05) e o escore histopatológico mostrou grau importante de sofrimento testicular esquerdo nos grupos G2 e G3 (p<0,05). Concluiu-se que o alopurinol näo foi capaz de proteger o testículo do rato contra os efeitos do fenômeno de isquemia/reperfusäo

Effect of 24-hour preservation with oxygen free radical scavengers on isolated-perfused canine heart-lungs.

The effectiveness of 24-hour hypothermic machine perfusion with TP-V (a hyperosmolar colloid solution containing dextrose, sucrose and ATP-MgCl2) alone, or in combination with oxygen free radical scavengers, was evaluated in isolated-perfused canine heart-lungs. Heart-lungs were perfused at 4 degrees C in either TP-V (n = 6), TP-V/Allopurinol (500 mg/L) (n = 6), or TP-V/Allopurinol (500 mg/L) & Catalase (5000 U/L) (n = 5). Lung inflation was maintained with 100% nitrogen. Following preservation, the heart-lungs were perfused with an albumin-mannitol perfusate for 3 hours at 37 degrees C, for functional, hemodynamic, and laboratory determinations. Cold preservation with TP-V/Allopurinol, and TP-V/Allopurinol & Catalase resulted in physiologically normal LDH levels during the 3-hour normothermic isolated perfusion test period. Significantly lower enzyme activity for CPK was evident at 0 (p less than .005) and 3 hours (p less than .05) of perfusion, while no significant differences in lactate production were seen among the groups. In addition, pH, PCO2, PO2, and left ventricular, aortic, and coronary artery pressures all remained within normal physiologic range, with no significant differences seen among the three groups. 99m Technetium scans demonstrated adequate patency among the heart-lungs, with better flow seen in those perfused with TP-V/Allopurinol & Catalase. Histological specimens confirmed a decrease in myocardial and pulmonary damage when Allopurinol and/or Catalase was used. It appears that oxygen free radical scavengers provide some protection from canine heart-lungs which have been hypothermically preserved for 24 hours.

Effect of 24 hour preservation with oxygen free radical scavengers on isolated perfused canine heart lungs

Los efectos de TP-V, una solución hiperosmolar con dextrosa, sucrosa, y ATP-MgCl2 fueron estudiados cuando usada sola o en combinación con substancias que eliminan los radicales libres de oxigenio, por 24 horas de perfusión hipotermica pulsátil de corazón pulmón y después revalorados en un sistema aislado de corazón pulmón a 37-C. Tres grupos de corazón pulmón de perros se analizaron: 1) TP-V (n=6), 2) TP-V con alopurinol (500mg/L) (m=6), 3) TP-V con alopurinol (500mg/L) y catalase (5000U/L) (n=5). Después de 24 horas de preservación, la preparación corazón pulmón fue perfundida con albúmina-manitol por 3 horas a 37-C con objeto de estimar su capacidad funcional y hemodinámica. Grupos 2 y 3 mostraron mejores valores de LDH y CPK a 0 t 3 horas de perfusión. Los valores de pH, pCO2, también como la presión ventricular izquierda, coronaria y aórtica, no cambinaron en forma significante. Histologicamente, el grupo 3 mostró mejor preservación del corazón y pulmones. En resúmen, podemos indicar que la solución TP-V, con las substancias que eliminan radicales libres de oxigeno, ofrecen una buena protección para la preparación corazón pulmón almacenada por 24 horas bajo hipotermia