Comparison of two chemical models to induce hepatic preneoplasia in male Wistar rats.

BACKGROUND: One established model to induce hepatic preneoplasia (HP) (DEN 150) uses diethylnitrosamine (DEN) as initiator agent and 2-acetylaminofluorene (2-AAF) as a promoter drug. In addition, both chemicals cause liver cholestasis and fibrosis. AIM: We compared DEN 150 model with another adapted by us, DEN 200 to simplify the first one and to evaluate the effectiveness of both treatments to induce HP in rats. MATERIAL AND METHODS: Male Wistar rats were divided in 3 groups: controls; DEN 150 (rats received 2 doses of DEN, 150 mg/kg body weight, 2 weeks apart, and then 2-AAF, 20 mg/kg body weight, 4 doses per week during 3 weeks); and DEN 200 (rats received a single dose of DEN 200 mg/kg body weight, and 2 weeks apart 2-AAF, 20 mg/kg body weight, 2 doses per week during 3 weeks). Four hepatic enzymes, prothrombin time percentage, the number of bile ductules, total collagen amount, the number of altered hepatic foci (AHF) per liver and the percentage of liver occupied by foci were analyzed. Results. There were no differences in the number of AHF per liver between treated groups. Rats from DEN 200 group showed a significant diminution in the volume of liver occupied by foci. DEN 200 group had no fibrosis and better hemostatic conditions than DEN 150 group. Both groups developed cholestasis. CONCLUSION: In conclusion, both protocols are good alternatives to induce HP in rats and the new protocol proposed is an effective and a simple methodology to provide subclinic states of liver cancer.

Structural, ultrastructural and functional studies of human cardiac valve allografts that suffered an increment of the cryostorage temperature.

Human cardiac valve allografts (HVAs) suffer injuries during the cryopreservation period. Here, we described structural, ultrastructural and functional damages suffered by HVAs after an increment of their cryostorage temperature (100 degree C). Two experimental groups of pulmonary and aortic HVAs were compared: cryopreserved (HVAcryo) and cryopreserved with temperature changes (HVAΔT). Transmission electron microscopy (TEM) was used to analyze valve fibroblasts and extracellular matrix morphology. Total collagen amount was estimated using two different methods and fibroblast viability was assessed measuring their oxygen consumption rate. Porcine heart grafts valves were used to set the techniques. Disorganized collagen network was seen in HVAΔT by TEM. Fibroblasts showed damages in the cellular membrane and many secretor vesicles. Mitochondria and chromatin were also altered. HVAΔT had less amount of collagen and fibroblasts showed an oxygen consumption rate markedly diminished compared to HVAcryo. The increment of 100 degree C suffered by HVAs caused damages that made them unsuitable for clinical purposes.

Morphological and biochemical analysis of human cardiac valve allografts after an increment of the cryostorage temperature.

Cryopreserved human cardiac valve allografts could suffer lethal damages if the temperature is elevated during cryostorage. This work describes the functional and morphological alterations suffered by human cardiac valve allografts after a gradual increment of the cryostorage temperature from -147 degrees C to -47 degrees C due to a technical failure. Three experimental groups of human pulmonary and aortic allografts were compared: fresh, cryopreserved (-147 degrees C) and cryopreserved with temperature changes from -147 degrees C up to -47 degrees C and back to -147 degrees C. Fibroblast functionality was studied to asses the degree of valvular damages. Collagen network was also analyzed with bright light field and polarized microscopy; an immunohistochemistry for procollagen I was performed and the MTT colorimetric assay was used to evaluate fibroblast mitochondrial enzymatic activity. Porcine heart grafts valves were used to set the MTT colorimetric assay. With bright light field microscopy, disorganized collagen network was seen together with interstitial edema in cryopreserved groups. Polarized microscopy showed that fresh allografts had abundant collagen type I and III, cryopreserved group had less amount of collagen type I and in allografts that suffered cryopreservation temperature elevation collagen type I synthesis could not been demonstrated. Procollagen I was present in fibroblast cytoplasm of fresh group, but it was diminished in cryopreserved group and was absent in the group that suffered temperature elevation. Temperature changes during the cryopreservation period of human cardiac valve allografts induced fibroblast activity reduction. When the cryopreservation temperature is elevated during cryostorage, fibroblasts lost their functionality and the allografts may be not suitable for transplant.

Morphological alterations of central nervous system (CNS) myelin in vanadium (V)-exposed adult rats.

In the present work we show morphological data of the in vivo susceptibility of CNS myelin to sodium metavanadate [V(+5)] in adult rats. The possible role of vanadium in behavioral alterations and in brain lipid peroxidation was also investigated. Animals were injected intraperitoneally (i.p.) with 3 mg/kg body weight (bw) of sodium metavanadate [1.25 V/kg bw/day] for 5 consecutive days. Open field and rotarod tests were performed the day after the last dose had been administered and then animals were sacrificed by different methods for histological and lipid peroxidation studies. The present results show that intraperitoneal administration of V(+5) to adult rats resulted in changes in locomotor activity, specific myelin stainings and lipid peroxidation in some brain areas. They support the notion that CNS myelin could be a preferential target of V(+5)-mediated lipid peroxidation in adult rats. The mechanisms underlying this action could affect the myelin sheath leading to behavioral perturbations.