Leonardo de Souza Mendonça

A critical analysis of three quantitative methods of assessment of hepatic steatosis in liver biopsies

The issue of adequately quantitatively evaluating hepatic steatosis is still unresolved. Therefore, we compared three methods of quantitative assessment. Two groups of mice (n = 10 each) were fed standard chow (10% fat, SC group) or a high-fat diet (60% fat, HF group) for 16 weeks, and hepatic triglyceride (HT) and liver tissue were then studied. Paraplast-embedded tissues stained by hematoxylin and eosin (H-E) were compared to frozen sections stained by Oil Red-O (ORO). In addition, the volume density of steatosis (Vv[steatosis, liver]) was measured by point counting (P-C, sections H-E or ORO) or by image analysis (I-A, sections ORO). HT was significantly higher in the HF group (104% greater, P = 0.0004) than in the SC group. With P-C and H-E, Vv[steatosis, liver] was 4.80 ± 0.90% in the SC group and 33.50 ± 3.17% in the HF group (600% greater, P < 0.0001). With P-C and ORO, Vv[steatosis, liver] was 4.86 ± 0.89% in the SC group and 25.21 ± 1.27% in the HF group (420% greater, P < 0.0001). With I-A and ORO, Vv[steatosis, liver] was 4.17 ± 0.85% in the SC group and 23.35 ± 1.58% in the HF group (460% greater, P < 0.0001). Correlations between Vv[steatosis, liver] and HT were strong and significant in all methods. In conclusion, all methods were appropriate and reproducible. In P-C and H-E, there is a slight overestimation of steatosis in the HF animals in comparison to frozen sections and ORO; in frozen sections, differences between P-C and I-A are insignificant.

Pan-PPAR agonist beneficial effects in overweight mice fed a high-fat high-sucrose diet.

OBJECTIVE We analyzed the effect of peroxisome proliferator-activated receptor (PPAR) agonists on adipose tissue morphology, adiponectin expression, and its relation to glucose and insulin levels in C57BL/6 mice fed a high-fat high-sucrose (HFHS) diet. METHODS Male C57BL/6 mice received one of five diets: standard chow, HFHS chow, or HFHS plus rosiglitazone (PPAR-gamma agonist), fenofibrate (PPAR-alpha agonist), or bezafibrate (pan-PPAR agonist). Diets were administered for 11 wk and medications from week 6 to week 11. Glucose intolerance (GI) and insulin resistance were evaluated by oral glucose tolerance testing and homeostasis model assessment for insulin resistance, respectively. Adipocyte diameter was analyzed in epididymal, inguinal, and retroperitoneal fat pads and by adiponectin immunostain. RESULTS Mice fed the HFHS chow had hyperglycemia, GI, insulin resistance, increased fat pad weight, adipocyte hypertrophy, and decreased adiponectin immunostaining. Rosiglitazone improved GI, insulin sensitiveness, and adiponectin immunostaining, but it resulted in body weight gain, hyperphagia, and adipocyte and heart hypertrophy. Fenofibrate improved all parameters except for fasting glucose and GI. Bezafibrate was the most efficient in decreasing body weight and glucose intolerance. CONCLUSION Activation of PPAR-alpha, -delta, and -gamma together is better than the activation of PPAR-alpha or -gamma alone, because bezafibrate showed a wider range of action on metabolic, morphologic, and biometric alterations due to an HFHS diet in mice.

Rosiglitazone aggravates nonalcoholic Fatty pancreatic disease in C57BL/6 mice fed high-fat and high-sucrose diet.

Objectives: Evaluate the effect of fenofibrate, bezafibrate, and rosiglitazone on nonalcoholic fatty pancreatic disease and islet peroxisome proliferator-activated receptor-&agr; (PPAR-&agr;) and PPAR-&bgr; immunostain in mice fed high-fat high-sucrose (HFHS) diet. Methods: Two-month-old male mice were fed standard chow (n = 10) or HFHS chow (n = 40) for 6 weeks. Afterward, HFHS mice were grouped by treatment: untreated HFHS and HFHS treated with rosiglitazone (HFHS-Ro), fenofibrate (HFHS-Fe), or bezafibrate (HFHS-Bz). Medications were administered for 5 weeks. After treatment, the pancreas was removed and analyzed by morphometry, stereology, and immunohistochemistry. Results: The HFHS-fed mice showed altered fasting glucose (+33%) and insulin (+138%); increased body (+20%) and pancreas (+28%) masses, pancreatic fat (+700%), islet hypertrophy (+38%); and decreased GLUT2 immunostain (−60%). Rosiglitazone reduced fasting glucose and insulin but induced weight gain. Fibrates impeded weight gain, but only bezafibrate prevented islet hypertrophy. The GLUT2 stain was improved in all treatments, and there were no alterations in PPAR-&agr;. There were morphological signs of pancreatitis with fenofibrate, although there were no alterations in amylase and lipase. Rosiglitazone exacerbated pancreatic fat infiltration (+75% vs HFHS group), and bezafibrate increased PPAR-&bgr; expression in pancreatic islets. Conclusions: Rosiglitazone is shown for the first time to exacerbate pancreatic fat infiltration; therefore, precaution has to be taken when rosiglitazone is prescribed to obese patients.

Swimming training beneficial effects in a mice model of nonalcoholic fatty liver disease

The study aimed to investigate the effect of swimming training in reducing the nonalcoholic fatty liver disease (NAFLD) and associated comorbidities, including the hepatic expression of fatty acid synthesis and peroxisome proliferator receptor activity-alpha. Male C57BL/6 mice were separated into two major groups according to their nutrition and studied during 22 weeks: standard chow (10% fat, SC) or high-fat chow (60% fat, HF), characterizing the sedentary groups SC-Sed and HF-Sed. In the last 10 weeks of the experiment, half of the sedentary groups were submitted to a swimming training with a progressive increase in duration, characterizing the exercised groups: SC-Ex and HF-Ex. At the end of the experiment, considering the findings in the SC-Sed group, HF-Sed group had significantly higher body mass, hyperglycemia, hyperinsulinemia with insulin resistance, hypertrophy of the adipocytes (with inflammatory infiltrate), hypertrophy of the pancreatic islets, dyslipidemia, altered liver enzymes and inflammatory cytokines, and NAFLD with changes in gene expression of hepatic lipogenic and oxidative proteins. The swimming program, even concomitant with the high-fat diet, reduced overweight and all the other worst findings, especially NAFLD. In conclusion, the swimming training can attenuate the morbid effects of a high-fat diet combined with sedentary lifestyle in mice. These data reinforce the notion that swimming exercise can be considered an efficient nonpharmacologic therapy in the treatment of NAFLD, obesity and insulin resistance.

Favorable cardiac and aortic remodeling in olmesartan-treated spontaneously hypertensive rats

Cardiovascular remodeling contributes to the progression of cardiovascular disease. Thus, our aim was to evaluate the action of long-term treatment with olmesartan on cardiac and aortic adverse remodeling and its relationship with blood pressure (BP) and tensile forces acting on the aortic wall. Five-month-old male rats were divided in: WKY group (n = 6), SHR group (n = 6), and SHRs treated with hydralazine 30 mg/kg/day (SHR-H, n = 8) or olmesartan 10 mg/kg/day (SHR-O, n = 8). Medications were administered for 16 weeks. The SHR group showed hypertension (189 ± 4 mmHg), cardiomyocyte hypertrophy (+107%), interstitial fibrosis (5.7% vs 1.9% in WKY), and reduced intramyocardial vascularization (9.1% vs 22.8% in WKY). In aorta, the SHRs showed outward hypertrophic remodeling, increased elastic fibers content (+36%), and increased circumferential wall tension (CWT, 2.79 × 104 dyne/cm) and tensile stress (TS, 261.4 × 104 dyne/cm2). Hydralazine and olmesartan decreased BP (−45% approximately) and likewise CWT and TS (−45% and −35% approximately). Both medications prevented left ventricle remodeling, but olmesartan improved cardiomyocyte hypertrophy better than hydralazine. Hydralazine did not alter media hypertrophy, but it enlarged lumen diameter and increased elastic fibers. It is unlikely that olmesartan prevented all aortic alterations. Taken together, long-term control of BP alone is not sufficient to prevent aortic remodeling due to hypertension, but in myocardium it seems to be enough, except for cardiomyocyte hypertrophy. The differential action of olmesartan suggests that it is essential to block growth stimulation by angiotensin II in cardiomyocytes and vascular smooth muscle cells in order to better prevent cardiovascular adverse remodeling due to arterial hypertension.

Cardiac and aortic structural alterations due to surgically-induced menopause associated with renovascular hypertension in rats.

Menopause and hypertension independently alter cardiovascular remodelling, but little is known about their effect on left ventricular and aortic wall remodelling. Eight‐weeks‐old Wistar rats were divided into four groups of six animals each: Sham group, OVX group (ovariectomized rats), 2K1C (two‐kidneys, one‐clip rats) and OVX + 2K1C group and kept until 19 weeks. Blood pressure (BP) increased 12% in OVX group, 35% in 2K1C and OVX + 2K1C groups compared with sham group. Vaginal cytology showed Sham and 2K1C rats cycling normally, whereas OVX and OVX + 2K1C rats were persistently in dioestrus or proestrus. At euthanasia, left ventricle (LV) and thoracic aorta were removed and analysed (immunohistochemistry and stereology). LV mass/tibia length ratio and cross‐sectional area of cardiomyocytes increased in all groups except Sham. The intramyocardial vascularization reduced 30% in comparison with Sham group, with no difference among OVX, 2K1C and OVX + 2K1C groups. The cardiac interstitium increased more than 45% in both 2K1C and OVX + 2K1C groups compared with Sham, but there was no significant difference between Sham and OVX groups. Nuclei number of LV cardiomyocyte diminished in OVX group, followed by 2K1C group and OVX + 2K1C group, with no difference between the 2K1C and the OVX + 2K1C groups. There was positive immunostaining for angiotensin II AT1 receptor in smooth muscle cell layer of aortic tunica media in all groups. These results show that both ovariectomy and renovascular hypertension enhance BP as a single stimulus and therefore produce adverse cardiac remodelling. However, renovascular hypertension exerts a far greater influence than surgically‐induced menopause in this parameter.

Rosiglitazone (peroxisome proliferator-activated receptor-gamma) counters hypertension and adverse cardiac and vascular remodeling in 2K1C hypertensive rats.

Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) agonists have been shown controlling blood pressure (BP) in spontaneously hypertensive rats and salt-sensitive hypertensive rats. The present study aims to test the hypothesis that PPAR-gamma agonist rosiglitazone has beneficial effects on cardiac and vascular adverse remodeling in a model of renovascular hypertension (two-kidneys-one-clip, 2K1C model). Wistar rats were divided into four groups (n=6): SHAM group, 2K1C, 2K1C+HYD (treated with hydralazine for 5 weeks) and 2K1C+ROSI (treated with rosiglitazone for 5 weeks). The left ventricle (LV), thoracic aorta (Ao) and common carotid artery (CCA) were analyzed. The BP did not show significant difference at the end of the experiment in groups 2K1C+ROSI, 2K1C+HYD and SHAM. The LV mass was smaller in 2K1C+ROSI compared with the other groups. The intima-media thickness was smaller in 2K1C+ROSI compared with untreated 2K1C ones, but not in 2K1C+HYD; 2K1C and 2K1C+HYD showed smaller Ao and CCA density of smooth muscle cell nuclei, and smaller surface density of the elastic lamellae than SHAM. The Ao and CCA circumferential wall tension and tensile stress were greater in 2K1C than in SHAM. Hypertrophied cardiomyocytes were seen in 2K1C, but not in 2K1C+ROSI and SHAM; 2K1C+ROSI had enhanced volume and length densities of intramyocardial arteries than 2K1C. The volume density of cardiac interstitium was greater in 2K1C and 2K1C+HYD than in SHAM. In conclusion, PPAR-gamma agonist rosiglitazone has beneficial effects controlling BP, reducing vascular adverse remodeling, and preserving intramyocardial vascularization in renovascular hypertensive rats (2K1C model).

Avaliação de métodos radiológicos na detecção de corpo estranho de madeira em modelo animal

ABSTRACT - Purpose: To determine the usefulness of different radiological methods in the diagnoses of wooden foreign bodies(FB). Methods: Eleven adult chickens were used. Each thigh received a puncture wound and in one of them a wooden splinter wasintroduced and left in place while in the contralateral it was introduced and removed (control group). After 7 days the animals wherekilled and the legs removed to be analyzed with conventional radiography (CR), ultrasonography (US), magnetic resonance andcomputed tomography. The results were viewed by 2 independent senior radiologists. Results: Sensitivity was: CR – 13.6%; US –63.6%; MR – 59.1%; and CT – 72.7%, with specificity of 100%, 100%, 95.5%, and 95.5%, respectively. The positive predictive valu efor CR and US was 100%, 95% for CT 95% and 93.8% for MR. CT had a negative predictive value of 78.3%, while US, MR, and CRhad 73.7%, 70.1%, and 53.7%, respectively. The accuracy for CT was 84.1%, followed by US – 81.8%, RM – 77.3%, and CR – 56.8%.Inflammatory reaction was histologically demonstrated in all thighs containing FB.

Beneficial Effects of Angiotensin II AT1 Blocker on Cardiovascular Adverse Remodeling Due to Nitric Oxide Synthesis Blockade

Se estudiaron con herramientas morfologicas, los efectos de diferentes dosis de Losartan sobre el remodelamiento cardiovascular, en ratas deficientes en oxido nitrico. 30 ratas Wistar, con 15 semanas de edad, fueron separadas en 6 grupos. control (C), L-NAME (LN), y 4 grupos en que administro LN junto con Losartan, en diferentes dosis (1, 5, 20 y 40 mg/kg/dia). El L-NAME fue administrado durante 9 semanas y la administracion de Losartan se inicio en la segunda semana de experimentacion. Se estudiaron el corazon, la parte toracica de la aorta y la arteria mesenterica craneal, con microscopia de luz y estereologia. La presion arterial (PA) aumento desde la primera semana de administracion de L-NAME. El tratamiento con Losartan, en las dosis de 20 y 40 mg/kg/dia, fue eficiente para reducir la PA despues de la septima semana de tratamiento. El remodelamiento cardiaco adverso en el grupo LN se caracterizo por intensa fibrosis intersticial, disminucion de la microvascularizacion miocardica e hipertrofia y consecuente perdida de cardiomiocitos. La estructura de la pared de la aorta (densidad por area de nucleos de celulas musculares lisas y densidad de superficie de lamelas), y la relacion media/luz de la arteria mesenterica craneal, tambien fueron muy alteradas por la administracion de L-NAME. Solo en una dosis igual o mayor que 20 mg/kg/dia, el Losartan tuvo efecto benefico tratando estas alteraciones. En conclusion, tanto el corazon como la pared arterial de ratas deficientes en oxido nitrico, presentan un proceso de remodelamiento acentuado, y este es eficientemente tratado con Losartan en diferentes dosis. La eficiencia del tratamiento con Losartan en el modelo de bloqueo de la sintesis de oxido nitrico se correlaciona con el efecto hipotensor de la droga, principalmente en las dosis mas elevadas