Péter Vajdovich

Free Radicals and Antioxidants in Inflammatory Processes and Ischemia-Reperfusion Injury

This article discusses the current understanding of the role of free radicals and antioxidants in inflammatory processes and in ischemia reperfusion injury. It begins by describing the manifestations of acute inflammation and outlining the cellular events that occur during inflammation. It then describes the biochemical mediators of inflammation with special attention to nitric oxide. It details the process of hypoxia reperfusion injury, the enzymes involved, its treatment, and studies involving specific hypoxia reperfusion injuries in various animal species.

Occurrence, clinical features and outcome of canine pancreatitis (80 cases)

Medical records of 80 dogs diagnosed with acute pancreatitis during a 4-year period were evaluated regarding history, breed predilection, clinical signs and additional examination findings. Cases were selected if compatible clinical symptoms, increased serum activity of amylase or lipase and morphologic evidence of pancreatitis by ultrasonography, laparotomy or necropsy were all present. Like in other studies, neutered dogs had an increased risk of developing acute pancreatitis. Although breed predilection was consistent with earlier reports, some notable differences were also observed. Apart from Dachshunds, Poodles, Cocker Spaniels and Fox Terriers, the sled dogs (Laikas, Alaskan Malamutes) also demonstrated a higher risk for pancreatitis according to our results. Concurrent diseases occurred in 56 dogs (70%), diabetes mellitus (n = 29, 36%) being the most common. Clinical signs of acute pancreatitis were similar to those observed in other studies. The study group represented a dog population with severe acute pancreatitis, having a relatively high mortality rate (40%) compared to data of the literature. Breed, age, gender, neutering and body condition had no significant association with the outcome. Hypothermia (p = 0.0413) and metabolic acidosis (p = 0.0063) correlated significantly with poor prognosis and may serve as valuable markers for severity assessment in canine acute pancreatitis.

Generation of a Homozygous Transgenic Rat Strain Stably Expressing a Calcium Sensor Protein for Direct Examination of Calcium Signaling

In drug discovery, prediction of selectivity and toxicity require the evaluation of cellular calcium homeostasis. The rat is a preferred laboratory animal for pharmacology and toxicology studies, while currently no calcium indicator protein expressing rat model is available. We established a transgenic rat strain stably expressing the GCaMP2 fluorescent calcium sensor by a transposon-based methodology. Zygotes were co-injected with mRNA of transposase and a CAG-GCaMP2 expressing construct, and animals with one transgene copy were pre-selected by measuring fluorescence in blood cells. A homozygous rat strain was generated with high sensor protein expression in the heart, kidney, liver, and blood cells. No pathological alterations were found in these animals, and fluorescence measurements in cardiac tissue slices and primary cultures demonstrated the applicability of this system for studying calcium signaling. We show here that the GCaMP2 expressing rat cardiomyocytes allow the prediction of cardiotoxic drug side-effects, and provide evidence for the role of Na+/Ca2+ exchanger and its beneficial pharmacological modulation in cardiac reperfusion. Our data indicate that drug-induced alterations and pathological processes can be followed by using this rat model, suggesting that transgenic rats expressing a calcium-sensitive protein provide a valuable system for pharmacological and toxicological studies.

Hematologic and Plasma Biochemistry Values in White Storks (Ciconia ciconia)

Abstract Hematologic and plasma biochemistry parameters of the white stork (Ciconia ciconia) were studied. Blood samples were taken from a total of 80 adult white storks kept in captivity in Hungarian zoos and bird repatriation stations, between 2002 and 2006. Hematologic (packed cell volume, 46.3% ± 5.3%; hemoglobin concentration, 127.8 ± 20.4 g/L; red blood cell counts, 2.28 ± 0.35 1012/l/l; white blood cell counts, 21.6 ± 4.2 109/l/l; heterophils, 61.0% ± 9.8% [13.1 ± 3.2 × 109/L]; lymphocytes, 34.3% ± 9.1% [7.4 ± 2.5 × 109/L]; monocytes, 3.44% ± 2.3% [0.78 ± 0.57 × 109/L]; eosinophils 0.75% ± 0.91% [0.16 ± 0.21 × 109/L]; basophils 0.38% ± 0.56% [0.04 ± 0.07 × 109/L]) and plasma biochemistry values (aspartate aminotransferase, 267.5 ± 145.8 U/L; L-γ-glutamyltransferase, 47.6 ± 49.3 U/L; lipase, 70.3 ± 60.6 U/L; creatine kinase, 443.9 ± 182.2 U/L; lactate dehydrogenase, 880.4 ± 293.6 U/L; alkaline phosphatase, 177.5 ± 116.6 U/L; amylase, 917.6 ± 314.3 U/L; glutamate dehydrogenase, 7.3 ± 4.0 U/L; total protein, 45.2 ± 8.1 g/L; uric acid, 459.2 ± 254.3 µmol/L; and bile acids, 46.3 ± 20.5 µmol/L) were determined. The results obtained can be used as reference values, because there are no established values previously reported for adult white storks.

Comparison between an intradermal skin test and allergen-specific IgE-ELISA for canine atopic dermatitis

The aim of this study was to compare the results of an intradermal skin test (IDST) with those of an allergen-specific IgE-ELISA in 210 dogs with atopic dermatitis. All the dogs had a clinical diagnosis of atopic dermatitis and underwent an IDST. The sera of all dogs were analysed for allergen-specific IgE by ELISA using the monoclonal antibody D9 against dog IgE. IDST was used as the standard assay. In both methods, the following antigens provided a positive test result: Dermatophagoides farinae, Acarus siro, Tyrophagus putrescentiae, ragweed, mugwort and Lepidoglyphus destructor. ELISA had an overall sensitivity of 82.4% and an overall specificity of 93.8%. The overall accuracy of the ELISA was 91.3%. The evaluated monoclonal D9 ELISA was found to be a reliable tool for the diagnosis of those allergens that cause clinical atopy, and can be recommended for use in dogs when immunotherapy is a therapeutic option.

Expression of multidrug resistance membrane transporter (Pgp) and p53 protein in canine mammary tumours.

The aim of this study was to determine the expression rate of P-glycoprotein (Pgp), a multidrug resistance marker and the p53 tumour-suppressor protein in canine mammary tumours. A total of 30 tumours were examined in parallel to patient history. The tumours were allotted to four groups: tubulopapillar carcinomas, complex carcinomas, benign tumours, and other malignant tumours. A monoclonal mouse antibody (C494) was used for the immunohistochemical evaluation of Pgp and a polyclonal rabbit antibody for p53. We found that the intact ductal epithelium and connective tissue showed pronounced Pgp expression. The most intensive staining was detected in tubulopapillar carcinomas for both Pgp and p53. The expression rate of Pgp and p53 differed significantly between tubulopapillar carcinoma and complex carcinoma, and between tubulopapillar carcinoma and benign mammary tumour, respectively. The expressions of Pgp and p53 highly correlated statistically; therefore, both can determine malignancy in a similar manner. In the case of tubulopapillar carcinomas, more relapsed tumours occurred than in relation to complex carcinomas and other malignant tumours. Pgp expression rate was proportional to the probability of the tumour becoming recidivant postoperatively, as well. These results suggest that routine evaluation of Pgp expression in canine mammary tumours may be prognostically helpful.

Pegylated liposomal formulation of doxorubicin overcomes drug resistance in a genetically engineered mouse model of breast cancer

Abstract Success of cancer treatment is often hampered by the emergence of multidrug resistance (MDR) mediated by P‐glycoprotein (ABCB1/Pgp). Doxorubicin (DOX) is recognized by Pgp and therefore it can induce therapy resistance in breast cancer patients. In this study our aim was to evaluate the susceptibility of the pegylated liposomal formulation of doxorubicin (PLD/Doxil®/Caelyx®) to MDR. We show that cells selected to be resistant to DOX are cross‐resistant to PLD and PLD is also ineffective in an allograft model of doxorubicin‐resistant mouse B‐cell leukemia. In contrast, PLD was far more efficient than DOX as reflected by a significant increase of both relapse‐free and overall survival of Brca1−/−;p53−/− mammary tumor bearing mice. Increased survival could be explained by the delayed onset of drug resistance. Consistent with the higher Pgp levels needed to confer resistance, PLD administration was able to overcome doxorubicin insensitivity of the mouse mammary tumors. Our results indicate that the favorable pharmacokinetics achieved with PLD can effectively overcome Pgp‐mediated resistance, suggesting that PLD therapy could be a promising strategy for the treatment of therapy‐resistant breast cancer patients. Graphical abstract Figure. No Caption available.

Studies on veterinary medicine

Preface Lester Mandelker Peter Vajdovich * Oxidative Stress, Free Radicals and Cellular Damage, Lester Mandelker DVM * Use of free radicals and antioxidants in inflammatory processes of animals Peter Vajdovich DVM, PHD * Oxidative Stress and Calcium Metabolism, Patricia Schenck DVM, PHD * TRPM2 Cation Channels and Oxidative Stress-Induced Neuronal Cell Death Mustafa Naziroglu1, PHD * Oxidative stress in diabetes mellitus Stefano Comazzi, DVM, PHD * Oxidative Stress in the Spinal Cord of Dogs and Cats Wendy Baltzer, DVM, PhD * Oxidative Stress, Cognitive Dysfunction and Brain Aging Elizabeth Head, Ph.D.,* and Steven C. Zicker DVM, PhD * The role of oxidative stress in ocular disease Gustavo L. Zapata PHD * Oxidative Stress in Heart Failure Gordon Moe, MD, MSc * Nutrient Selection in the Management of Canine Atopic Dermatitis John Kuck DVM * Avian antioxidants and oxidative stress: highlights from studies of food, physiology, and feathers Kevin McGraw DVM * Free Radicals and Antioxidants in Avian Diseases Miklos Mezes, PhD and Krisztian Balogh, PhD * Oxidative Stress In Ruminants Pietro Celi (DVM, PhD) * Antioxidant Effects of Supplements Lester Mandelker DVM and Peter Vajdovich DVM, PHD

The effect of indomethacin, myeloperoxidase, and certain steroid hormones on bactericidal activity: an ex vivo and in vivo experimental study

BackgroundThe role of myeloperoxidase (MPO) is essential in the killing of phagocytosed bacteria. Certain steroid hormones increase MPO plasma concentration. Our aim was to test the effect of MPO, its inhibitor indomethacin, and certain steroid hormones on bactericidal activity.MethodsHuman polymorphonuclear leukocytes (PMN) were incubated with opsonised Escherichia coli and either MPO, indomethacin, estradiol, or hydrocortisone. Intracellular killing capacity was evaluated with UV microscopy after treatment with fluorescent dye. Next, an in vivo experiment was performed with nine groups of rats: in the first phase of the study indomethacin treatment and Pasteurella multocida infection (Ii), indomethacin treatment without infection (I0), untreated control with infection (Mi) and untreated control without infection (M0); in the second phase of the study rats with infection and testosterone treatment (NT), castration, infection and testosterone treatment (CT), castration, infection and estradiol treatment (CE), non-castrated infected control (N0), and castrated infected control (C0). After treatment bacteria were reisolated from the liver and heart blood on agar plates, and laboratory parameters were analyzed. For the comparison of laboratory results ANOVA or Kruskal-Wallis test and LSD post hoc test was used.ResultsIndomethacin did not have a remarkable effect on the bacterial killing of PMNs, while the other compounds increased bacterial killing to various degrees. In the animal model indomethacin and infection caused a poor clinical state, a great number of reisolated bacteria, elevated white blood cell (WBC) count, decreased C-reactive protein (CRP) and serum albumin levels. Testosterone treatment resulted in less bacterial colony numbers in group NT, but not in group CT compared to respective controls (N0, C0). Estradiol treatment (CE) decreased colony numbers compared to control (C0). Hormone administration resulted in lower WBC counts, and in group CE, a decreased CRP.ConclusionsMPO, estradiol, and hydrocortisone improve bacterial killing activity of PMNs. Indomethacin treatment and castration weaken immune responses and clinical state of infected rats, while testosterone and estradiol have a beneficial effect.

Oxidative stress in the blood of pregnant rats and reduction of organ weights caused by the polychlorinated biphenyl congener 77

3,3′,4,4′-Tetrachlorobiphenyl (PCB 77), one of the environmentally persistent polychlorinated biphenyls that have been used for industrial purposes, was repeatedly administered to pregnant rats by gavage at a dose of minimal, non-lethal toxicity in order to study its effects on routine blood variables, parameters of oxidative stress and hematopoietic organs in pregnant female rats. Of the routine blood parameters, PCB 77 reduced the mean corpuscular hemoglobin concentration and platelet counts; the levels of malondialdehyde and glutathione peroxidase in the blood were higher during the first days of gestation (1–7), as compared to the respective controls. In the subsequent period between days 8 and 18, these parameters did not show any significant change after PCB 77 treatment. Routine blood parameters and oxidative stress parameters indicated a moderate degree of oxidative stress which alone could not bring about the serious weight reduction of the thymus, pituitary, and kidneys. The extent of oxidative stress did not correlate with the weight reduction of some of the blood-forming organs.