Abstract. The types of lesion instability responsible for the majority of acute coronary events frequently include plaque disruption and plaque erosion with superimposed thrombosis. The term 'vulnerable plaque' is used to describe atherosclerotic (ATS) plaques that are particularly prone to rupture and susceptible to thrombus formation, such as the thin-cap fibroatheroma (TCFA). The aim of the present study was to assess the morphological and histological differences between plaques that are unstable and those that are vulnerable to instability. Carotid artery endarterectomy specimens were obtained from 26 patients with carotid artery stenosis, consisting of 20 men and 6 women (age range, 35-80 years). Histological and morphometric methods were used to visualize and characterize the ATS plaques. Among the 26 carotid ATS plaques, 23% were stable, 23% were unstable and 54% were vulnerable. With regard to morphometric characteristics, the following mean values were obtained for the TCFA and unstable plaques, respectively: Fibrous cap thickness, 21.91 and 11.66 µM; proportion of necrotic core area in the total plaque area, 25.90 and 22.03%; and the proportion of inflammatory area in the total plaque area, 8.41 and 3.04%. No plaque calcification was observed in any of them. Since ATS coronary artery disease is considerably widespread and fatal, it is crucial to further study ATS lesions to obtain an improved understanding of the nature of vulnerable and unstable plaques. The methods used to detect plaque size, necrotic core area and fibrous cap thickness are considered to be particularly useful for identifying vulnerable and unstable plaques.

Abstract. Postoperative atrial fibrillation (POAF) is a common complication subsequent to cardiac surgery. Various risk factors have been reported for the development of this complication; however, their precise role in POAF is unknown. In the present study, we attempted to identify clinical factors and histopathological changes in atrial tissue that may predict the development of POAF. Atrial tissue was sampled from 103 patients in sinus rhythm that had undergone open-heart surgery, including elective coronary artery bypass grafting (79.61%) and heart valve surgery (20.38%). Atrial surgical biopsies were obtained from the right atrial appendage at the site of cannulation, prior to cardiopulmonary bypass. Tissues were processed routinely for light microscopy, then stained with hematoxylin and eosin and sirius red. Microscopical exams were used to observe the atrial lesions and morphometry was conducted for quantification. In total, 37 patients (35.92%) developed POAF and atrial lesions were identified in the majority of patients in the normal postoperative sinus rhythm and POAF groups, but were most common in the POAF patients. The most common risk factors involved in developing POAF were found to be: Age of >60 years, male gender, ejection fraction of <50% and increased pulmonary hypertension. Furthermore, interstitial fibrosis and myocytolysis were the most common injuries identified. Abnormalities in atrial surgical biopsies may indicate the susceptibility of a patient to developing POAF. The present results suggest that the pre-existent alterations in the structure of the right atrium may be a major determinant in the development of POAF.

To examine the effect of high dose vitamin D3 treatment on visceral adipose tissue, we used vitamin D deficient male Wistar rats (18 months old) as a model of sarcopenia. The aging process is not only responsive for the losing muscle mass but also for redistribution of lipid resulting in altered fatty acid storage and dysdifferentiation of mesenchymal precursors. The effect of aging and vitamin D treatment (weekly oral gavage with 0.125 mg vitamin D3 (5000 IU)/100g body weight) on the omental adipose tissue were histological examinated. At the end of the experiment (9 monhs), adaptive changes to the reduction of adipogenesis and increased apoptosis in response to long-term treatment with vitamin D consisted of smaller size of adipocyte and moderate macrophage infiltrate.

This study investigated the effects of flaxseed and vitamin E on diabetic nephropathy lesions in an experimental-induced model of diabetes in hamsters. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) in male Golden Syrian hamsters, and diabetic animals were fed either standard diet, or standard diet supplemented with flaxseed (150 g/kg diet), vitamin E (400 mg a-tocopherol/kg diet) or combination of flaxseed and vitamin E in the same dosages, for 20 weeks. Kidney histological evaluation of the diabetic hamsters revealed histological lesions characteristic for diabetic nephropathy, while supplementation of the diet with flaxseed and/or vitamin E improved histological aspects of diabetic nephropathy.

Routinely measuring epicardial fat had become a novel tool for cardiovascular risk stratification. Structural changes in epicardial adipose tissue (EAT), including fat thickness, inflammation, and angiogenesis, have been described in coronary artery disease (CAD) patients. We proposed to measure EAT thickness and characterize inflammatory infiltrate and angiogenesis in epicardial adipose tissue in CAD patients with and without chronic heart failure (CHF), established by cardiac dysfunction on echocardiography (left ventricular ejection fraction, LVEF ≤ 50%) and symptoms of heart failure (New York Heart Association (NYHA) functional class II or III).The study included 15 patients with CAD (demonstrated by coronary angiography),, who underwent right atrial appendages (RAA) excision during coronary artery bypass graft (CABG). The study was performed by histopathological, immunohistochemical (IHC), and morphometrical analysis. EAT thickness was assessed by using morphometry applied on routine histological stains. Inflammatory cell infiltration and angiogenesis were investigated immunohistochemically by using antibodies against CD68 and CD34 markers. Diminished EAT thickness in the CAD patients with CHF was associated with increased macrophage infiltration and reduced angiogenesis of the EAT as compared to CAD patients without CHF. In conclusion, the present study on epicardial fat samples of the RAA suggested that high expression of CD68 appeared to be associated with severe deterioration of heart function in CAD patients who underwent myocardial revascularization consisting of CABG.