Resistance against the development of diethylnitrosamine-induced hepatocellular carcinoma in female C3H mice: an experimental model.

Histopathological features of hepatocellular carcinoma (HCC) induced by diethylnitrosamine (DEN) in mice display strong similarities with those seen in humans, including the higher tumor prevalence in males than in females. Previous studies have demonstrated that continual production of the pro-inflammatory IL-6 by Kupffer cells is involved in the initiation and progression of DEN-induced HCC and that estrogen-mediated reduction of IL-6 secretion would decrease its incidence in females. Given the predominant utilization of male mice in hepatic carcinogenesis research, the objective of this study was to examine histopathological and immunological parameters in the DEN-induced liver carcinogenesis model in female C3H mice. We observed a significant prevalence of hepatocellular hyperplasias and adenomas alongside a minimal infiltration of inflammatory cells and a scarcity of senescent areas in females. Further, a low expression of immunosuppression markers is observed in females - such as neutrophil/lymphocyte ratio, PD-1 expression in CD8 T cells, and PD-L1 in myeloid cells - compared to males. Comparative studies between susceptible and resistant hosts to chemical carcinogenesis may help to unveil novel therapeutic strategies against cancer.

Analysis of the value of copper erythrocyte concentration measurement in the diagnosis of copper deficiency in bovines.

BACKGROUND: A reliable and practical method for assessing Cu status in live animals is not available. Blood Cu levels may not accurately reflect the true Cu status of the herd, and can over-predict Cu status during stress and inflammation. On the other hand, assessment of liver Cu is the most reliable indicator of Cu stores, but it is an invasive procedure that requires specialized training. The aim of this study was to evaluate the usefulness of Cu levels in red blood cells to determine the Cu status, with special emphasis in their correlation with erythrocyte Cu, Zn superoxide dismutase enzyme activity (ESOD), in bovines with Cu deficiency induced by high molybdenum and sulfur levels in the diet. METHODS: Three similar assays were performed, with a total of twenty eight calves. The Cu-deficient group (n = 15) received a basal diet supplemented with 11 mg of Mo/kg DM as sodium molybdate, and S as sodium sulfate. The control group (n = 13) received a basal diet supplemented with 9 mg of Cu/kg DM as copper sulfate. Samples of blood and liver were taken every 28-35 days. Cu levels were measured in liver (expressed as µg/g DM), plasma (expressed as µg/dl), and erythrocytes (expressed as µg/g Hb) by flame atomic absorption spectroscopy. Superoxide dismutase (SOD1) activity was determined in red blood cells and was expressed as IU/mg hemoglobin. InfoStat Statistical Software 2020 was used for the statistical analysis. Cu levels in plasma, red blood cells and liver, and ESOD activity were analyzed by ANOVA. The correlation between erythrocyte Cu levels and the rest of the parameters were analyzed by Pearson Correlation test. Unweighted Least Squares Linear Regression of SOD1 was developed. The autocorrelation between the monthly measurements was also determined by Durbin-Watson test and autocorrelation function. RESULTS: The assays lasted 314-341 days, approximately. Levels indicative of Cu deficiency for bovines were detected at 224 days (23 ± 11.6 µg/g DM) for liver Cu concentration; and at 198 days (55 ± 10.4 µg/dl) for plasma Cu concentration, in Cu-deficient animals. Liver and plasma Cu values indicative of Cu deficiency were not observed in the control group. Pearson Correlation test indicated that all indices of Cu status used in this study were significantly correlated. The highest value was obtained between ESOD and red blood Cu (0.74). There was a significant correlation between red blood Cu and plasma Cu (0.65), and with hepatic Cu (0.57). ESOD activity showed a similar significant positive correlation with liver Cu concentrations and with plasma Cu (0.59 and 0.58, respectively). CONCLUSION: The extremely low levels of liver and plasma Cu, the ESOD activity, erythrocyte Cu levels, and the periocular achromotrichia observed in the Cu-deficient animals showed that the clinic phase of Cu deficiency was reached in this group. The ESOD activity and erythrocyte Cu levels showed a strong association, indicating that the values of erythrocyte Cu may serve as an effective tool in assessing Cu status and diagnose a long-term Cu deficiency in cattle.

Decrease lysyl oxidase activity in hearts of copper-deficient bovines.

BACKGROUND: Lysyl oxidase (LOX) is a metalloenzyme that requires Cu as a cofactor and it is responsible for the formation of collagen and elastin cross-linking. The objective of this work was to measure the LOX enzyme activity in the heart of bovines with Cu deficiency induced by high molybdenum and sulfur levels in the diet. METHODS: Eighteen myocardial samples were obtained from Cu-deficient (n = 9) and control (n = 9) Holstein bovines during two similar assays. The samples were frozen in liquid nitrogen and stored at -70 °C to measure enzymatic activity. A commercial kit was used, following producer instructions. RESULTS: The results showed that LOX activity from the hearts of Cu-deficient bovines is 29 % lower than the ones of control bovines, being this difference statistically significant (p = 0.03). CONCLUSION: To our knowledge, this is the first report that determined LOX enzymatic activity in bovine heart of Cu-deficient animals. The microscopic alterations found in these animals in our previous work, could be explained by a diminished LOX activity. The results are in agreement with other authors, who found a relationship between LOX activity and dietary Cu intake. The information provided by this work could help to clarify the pathogenesis of cardiac lesions in cattle with dietary Cu deficiency.

Biochemical and Morphological Alterations in Hearts of Copper-Deficient Bovines.

Copper deficiency is an important disease of cattle that produces several clinical signs and lesions, due to alterations in copper-dependent enzymes. One of the organs affected by this deficiency is the heart (falling disease), but nevertheless, these cardiac lesions have not been extensively studied in bovines. The aim of this work was to propose a possible pathogenic mechanism for cardiac lesions in cattle affected by copper deficiency. Because of the possible existence of oxidative distress caused by low levels of copper-zinc-superoxide dismutase and cytochrome oxidase, ultrastructural and histological lesions have been evaluated in the heart of bovines in which a Cu deficiency had been induced using high molybdenum and sulfur levels in the diet. Our results indicated that copper deficiency produces significant damage in myocardium with high levels of lipid oxidation and a significant reduction in copper-zinc-superoxide dismutase activity leading to an oxidative distress situation. However, cytochrome oxidase activity was not significantly reduced. Histological observation revealed a significant increase in the amount of connective tissue, enlarged basement membranes of myocytes, and numerous Anichkov cells, in the hearts of deficient animals. Ultrastructural observation showed a significant enhancement in the mitochondrial volume density, with presence of lesions such as swelling and cristae disruption. We conclude that copper deficiency in bovines causes morphological lesions in the heart due to an oxidative damage produced by copper-dependent enzyme alterations.

Fatal canine encephalitozoonosis in Latin America, first report.

Encephalitozoon cuniculi is an obligate, intracellular microsporidian organism capable of establish infection in a wide variety of animals. In carnivores it may cause a sporadic, severe disease in the first few months of life, which usually culminates with the death of the animal. The objective of this study was to report a natural fatal case of encephalitozoonosis in a puppy from Argentina. Clinical signs included reduced appetite, depression, vocalizing, weight loss, weakness, convulsions and recumbency. No significant gross lesions were noticed at necropsy. Microscopically, severe, diffuse, lymphocytic encephalitis was seen. Large cytoplasmic vacuoles containing spores, morphologically compatible with E. cuniculi, were present within endothelial cells of brain and kidney, in renal tubular epithelium and hepatocytes. Encephalitozoon cuniculi DNA was detected by PCR in the kidney. Antibody titers to E. cuniculi in serum from the surviving puppies and the dam were ≥1:200. This report contributes to our understanding of neurologic disease in puppies. Encephalitozoonosis should be considered as a differential diagnosis in cases of fatal encephalitis in puppies.

Moraxella bovis pathogenicity: an update.

Moraxella bovis is the etiologic agent of infectious bovine keratoconjunctivitis, the most important ocular disease affecting cattle worldwide. The severity of the cases varied from eyes that exhibited mild signs to severe clinical cases with profuse lacrimation, conjunctival swelling, corneal opacity, and ulceration. Although the mortality is low, there is a high morbidity and important economic loss in terms of significant reduction in production. This paper examines aspects such as the pathogenesis of the disease and the mechanisms by which this unique bacterium is able to disrupt the corneal epithelium and cause infection.