Lymphoma is a very common lymphoid neoplasm in domestic animals, but few naturally occurring cases have been reported in rabbits. It presents at different sites within rabbits and, although the macroscopic pattern tends to be similar, different cell populations may be involved. This report describes a case of spontaneous lymphoma ocurring in a two-and-a-half-year-old pet Dutch dwarf rabbit. T and B lymphocyte infiltrates were observed in skin, lung, kidney, liver, intestine and lymph nodes, in each case affecting one or more tissue structures. The diagnosis, based on microscopic and immunocytochemical findings, was multicentric, T cell-rich B cell lymphoma with skin involvement.

In this work we have studied the effects of pharmacological concentrations of melatonin (1 µM–1 mM) on pancreatic stellate cells (PSC). Cell viability was analyzed by AlamarBlue test. Production of reactive oxygen species (ROS) was monitored following CM-H2DCFDA and MitoSOX Red-derived fluorescence. Total protein carbonyls and lipid peroxidation were analyzed by HPLC and spectrophotometric methods respectively. Mitochondrial membrane potential (ψm) was monitored by TMRM-derived fluorescence. Reduced (GSH) and oxidized (GSSG) levels of glutathione were determined by fluorescence techniques. Quantitative reverse transcription-polymerase chain reaction was employed to detect the expression of Nrf2-regulated antioxidant enzymes. Determination of SOD activity and total antioxidant capacity (TAC) were carried out by colorimetric methods, whereas expression of SOD was analyzed by Western blotting and RT-qPCR. The results show that melatonin decreased PSC viability in a concentration-dependent manner. Melatonin evoked a concentration-dependent increase in ROS production in the mitochondria and in the cytosol. Oxidation of proteins was detected in the presence of melatonin, whereas lipids oxidation was not observed. Depolarization of ψm was noted with 1 mM melatonin. A decrease in the GSH/GSSG ratio was observed, that depended on the concentration of melatonin used. A concentration-dependent increase in the expression of the antioxidant enzymes catalytic subunit of glutamate-cysteine ligase, catalase, NAD(P)H-quinone oxidoreductase 1 and heme oxygenase-1 was detected in cells incubated with melatonin. Finally, decreases in the expression and in the activity of superoxide dismutase were observed. We conclude that pharmacological concentrations melatonin modify the redox state of PSC, which might decrease cellular viability.

Background information. Pancreatic stellate cells play a key role in the fibrosis that develops in diseases such as pancreatic cancer. In the growing tumour, a hypoxia condition develops under which cancer cells are able to proliferate. The growth of fibrotic tissue contributes to hypoxia. In this study, the effect of hypoxia (1% O 2) on pancreatic stellate cells physiology was investigated. Changes in intracellular free-Ca 2+ concentration, mitochondrial free-Ca 2+ concentration and mitochondrial membrane potential were studied by fluorescence techniques. The status of enzymes responsible for the cellular oxidative state was analyzed by quantitative reverse transcriptionpolymerase chain reaction, high-performance liquid chromatography, spectrophotometric and fluorimetric methods and by Western blotting analysis. Cell viability and proliferation were studied by crystal violet test, 5-bromo-2deoxyuridine cell proliferation test and Western blotting analysis. Finally, cell migration was studied employing the wound healing assay. Results. Hypoxia induced an increase in intracellular and mitochondrial free-Ca 2+ concentration, whereas mitochondrial membrane potential was decreased. An increase in mitochondrial reactive oxygen species production was observed. Additionally, an increase in the oxidation of proteins and lipids was detected. Moreover, cellular total antioxidant capacity was decreased. Increases in the expression of superoxide dismutase 1 and 2 were observed and superoxide dismutase activity was augmented. Hypoxia evoked a decrease in the oxidized/reduced glutathione ratio. An increase in the phosphorylation of nuclear factor erythroid 2-related factor and in expression of the antioxidant enzymes catalytic subunit of glutamate-cysteine ligase, catalase, NAD(P)H-quinone oxidoreductase 1 and heme oxygenase-1 were detected. The expression of cyclin A was decreased, whereas expression of cyclin D and the content of 5-bromo-2-deoxyuridine were increased. This was accompanied by an increase in cell viability. The phosphorylation state of c-Jun NH 2-terminal kinase was increased, whereas that of p44/42 and p38 was decreased. Finally, cells subjected to hypoxia maintained migration ability. Conclusions and Significance. Hypoxia creates pro-oxidant conditions in pancreatic stellate cells to which cells adapt and leads to increased viability and proliferation.

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We investigated if residues of simazine in the natural waters would cause histological, hematological, and biochemical alterations in carps from contaminated areas in Badajoz (Spain). Some necrotic foci in kidney and liver, hepatitis, and hepatic steatosis were detected. No changes on measured hematological and biochemical parameters between fish from reference and contaminated ponds were observed. To assess if simazine exposure was the cause of these observations carps were exposed in the laboratory to simazine (45 microg/L) for 90 days. Some results obtained in the field were confirmed in laboratory, such as necrosis in kidney and liver and hepatic steatosis. Globular eosinophilic foci in kidney and a slight decrease of the hematocrit were also detected. These changes were moderate and indicative of an adaptation of the fish to the toxic stress caused by exposure to low simazine concentrations.