Massimiliano Mancini

Efficient mitochondrial biogenesis drives incomplete penetrance in Leber’s hereditary optic neuropathy

The mechanisms of incomplete penetrance in Leber’s hereditary optic neuropathy are elusive. Giordano et al. show that mitochondrial DNA content and mitochondrial mass are both increased in tissues and cells from unaffected mutation carriers relative to affected relatives and control individuals. Upregulation of mitochondrial biogenesis may represent a therapeutic target.

Endonuclease G is a novel determinant of cardiac hypertrophy and mitochondrial function.

Left ventricular mass (LVM) is a highly heritable trait and an independent risk factor for all-cause mortality. So far, genome-wide association studies have not identified the genetic factors that underlie LVM variation, and the regulatory mechanisms for blood-pressure-independent cardiac hypertrophy remain poorly understood. Unbiased systems genetics approaches in the rat now provide a powerful complementary tool to genome-wide association studies, and we applied integrative genomics to dissect a highly replicated, blood-pressure-independent LVM locus on rat chromosome 3p. Here we identified endonuclease G (Endog), which previously was implicated in apoptosis but not hypertrophy, as the gene at the locus, and we found a loss-of-function mutation in Endog that is associated with increased LVM and impaired cardiac function. Inhibition of Endog in cultured cardiomyocytes resulted in an increase in cell size and hypertrophic biomarkers in the absence of pro-hypertrophic stimulation. Genome-wide network analysis unexpectedly implicated ENDOG in fundamental mitochondrial processes that are unrelated to apoptosis. We showed direct regulation of ENDOG by ERR-α and PGC1α (which are master regulators of mitochondrial and cardiac function), interaction of ENDOG with the mitochondrial genome and ENDOG-mediated regulation of mitochondrial mass. At baseline, the Endog-deleted mouse heart had depleted mitochondria, mitochondrial dysfunction and elevated levels of reactive oxygen species, which were associated with enlarged and steatotic cardiomyocytes. Our study has further established the link between mitochondrial dysfunction, reactive oxygen species and heart disease and has uncovered a role for Endog in maladaptive cardiac hypertrophy.

Histopathologic Analysis of Peritumoral Pseudocapsule and Surgical Margin Status after Tumor Enucleation for Renal Cell Carcinoma

BACKGROUND The oncologic safety of blunt tumor enucleation (TE) of renal cell carcinoma (RCC) depends on the presence of a continuous pseudocapsule (PS) around the tumor and on the possibility of obtaining negative surgical margins (SMs). OBJECTIVE To investigate the PS and SMs after TE to define the real need to take a rim of healthy parenchyma around the tumor to avoid the risk of positive SMs. The risk of PS invasion related to other clinical and pathologic variables was also evaluated. DESIGN, SETTING, AND PARTICIPANTS Between September 2006 and December 2007, data were gathered prospectively from 187 consecutive patients who had kidney surgery. Overall, 90 consecutive patients who had TE for RCC were eligible for the study. All specimens were evaluated using an image analyzer by a dedicated uropathologist. INTERVENTION TE was done by blunt dissection using the natural cleavage plane between the tumor and the normal parenchyma. MEASUREMENTS PS, SM, and routinely available clinical and pathologic variables were recorded. RESULTS AND LIMITATIONS In 60 RCC tumors (67%) the PS was intact and free from invasion (PS-) while in 30 (33%) there were signs of penetration within its layers, with or without invasion beyond it. Indeed, 26.6% had PS that had been penetrated on the parenchymal side and 6.6% had penetration on the perirenal fat tissue side. The odds of having PS penetration increased significantly with an increase in clinical tumor size. PS penetration was also significantly associated with pathologic tumor dimensions and grade. In all cases the SMs were negative after TE. The present patients, followed for >2 yr, will enable us to correlate the risk of local recurrence with PS status. CONCLUSIONS The risk of PS penetration is associated with clinical and pathologic tumor dimensions and grade. If there is PS invasion into normal parenchyma, the presence of a thin layer of tissue allows for negative SM even if a TE is performed.

Perindopril and indapamide reverse coronary microvascular remodelling and improve flow in arterial hypertension

Objectives Patients and animal models of arterial hypertension are characterized by structural and functional abnormalities of the coronary microcirculation. Using a translational approach, we ascertained whether antihypertensive treatment can reverse microvascular remodelling and improve myocardial perfusion. Methods In 20 hypertensive patients with left ventricular hypertrophy, blood pressure, left ventricular mass index and myocardial blood flow were measured at baseline and after 6 months of treatment with perindopril + indapamide. In spontaneously hypertensive rats, blood pressure, coronary flow and histomorphometry of intramural coronary arterioles were measured after 8 weeks of treatment with placebo or perindopril + indapamide. Results In patients, treatment decreased blood pressure (161 ± 10/96 ± 5 to 136 ± 12/81 ± 6 mmHg; P < 0.0001) and left ventricular mass index (93 ± 16 to 85 ± 17 g/m2; P < 0.01) while increasing baseline (0.69 ± 0.13 to 0.88 ± 0.36 ml/min per g; P < 0.05) and hyperaemic myocardial blood flow (1.42 ± 0.32 to 1.94 ± 0.99 ml/min per g; P < 0.05). In rats treated with perindopril + indapamide (n = 11), blood pressure was 93 ± 18/55 ± 18 mmHg compared to 215 ± 18/161 ± 17 mmHg in placebo (n = 6; P < 0.001), baseline flow was unchanged whilst hyperaemic coronary flow was 19.89 ± 3.50 vs. 12.15 ± 0.99 ml/min per g, respectively (P < 0.01). The medial area of intramural arterioles was 1613 ± 409 with perindopril + indapamide and 8118 ± 901 μm2 with placebo (P < 0.001). Conclusion In patients with arterial hypertension and left ventricular hypertrophy, perindopril + indapamide reduced blood pressure and left ventricular mass index and improved resting and hyperaemic myocardial blood flow. Data in rats provide evidence that the improvement in coronary flow observed after treatment is due to reverse remodelling of intramural coronary arterioles and improved microvascular function.

Severe Mechanical Dyssynchrony Causes Regional Hibernation-Like Changes in Pigs With Nonischemic Heart Failure

BACKGROUND Sustained left ventricular (LV) dyssynchrony can lead to heart failure (HF) in the absence of coronary artery stenosis. We tested whether myocardial hibernation underlies the LV functional impairment caused by high-frequency pacing, an established model of nonischemic dilated cardiomyopathy. METHODS AND RESULTS Regional LV contractile and perfusion reserve were assessed by magnetic resonance imaging, respectively, as end-systolic wall thickening (LVESWT) and myocardial perfusion reserve index (MPRI) at rest and during low-dose dobutamine stress (LDDS, 10 microg.kg.min intravenously for 10minutes) in failing minipigs (n=8). LV tissue was analyzed for glycogen deposits and other molecular hallmarks of hibernation. LDDS caused a marked increase in LVESWT (27+/-2.98 vs. 7.15+/-3 %, P < .05) and MPRI (2.1+/-0.5 vs. 1.3+/-0.3 P < .05) in the region that was activated first (pacing site) compared with the opposite region. Myocardial glycogen content was markedly increased in the pacing site (P < .05 vs. opposite region). In addition, gene expression of glycogen phosphorylase was reduced in pacing site compared with opposite regions (0.71+/-0.1 vs. 1.03+/-0.3, P < .05), whereas that of hexokinase type II was globally reduced by 83%. CONCLUSIONS The combination of high heart rate and sustained dyssynchronous LV contraction causes asymmetrical myocardial hibernation, in absence of coronary artery stenosis.

High-intensity focused ultrasound in breast pathology: non-invasive treatment of benign and malignant lesions

Breast neoplasms are one of the leading causes of morbidity and mortality in women. Even if surgery is the treatment of choice, other forms of less invasive radical treatment are desirable. High-intensity focused ultrasound is already established as a valid non-invasive technique that ensures tumor ablation in various organs. The use of ultrasound or magnetic resonance guidance allows having some advantages such as the capability to treat tumors in moving organs or the possibility to have a real-time monitoring of the temperature increase. The aim of this paper is to report the use of high-intensity focused ultrasound technique with ultrasound and magnetic resonance guidance for the ablation of breast tumors, including both benign and malignant lesions.

Impaired mitochondrial biogenesis is a common feature to myocardial hypertrophy and end-stage ischemic heart failure

Mitochondrial (mt) DNA depletion and oxidative mtDNA damage have been implicated in the process of pathological cardiac remodeling. Whether these features are present in the early phase of maladaptive cardiac remodeling, that is, during compensated cardiac hypertrophy, is still unknown. We compared the morphologic and molecular features of mt biogenesis and markers of oxidative stress in human heart from adult subjects with compensated hypertrophic cardiomyopathy and heart failure. We have shown that mtDNA depletion is a constant feature of both conditions. A quantitative loss of mtDNA content was associated with significant down-regulation of selected modulators of mt biogenesis and decreased expression of proteins involved in mtDNA maintenance. Interestingly, mtDNA depletion characterized also the end-stage phase of cardiomyopathies due to a primary mtDNA defect. Oxidative stress damage was detected only in failing myocardium.

Endomyocardial Biopsy Guided by Electroanatomic Voltage Mapping in Arrhythmogenic Right Ventricular Cardiomyopathy: A Case Report

A positive endomyocardial biopsy (EMB) is a major diagnostic criterion for arrhythmogenic right ventricular cardiomyopathy (ARVC). Nevertheless, its sensitivity is low due to the focal nature of the disease. Moreover, myocardial samples are usually taken from the uncommonly involved interventricular septum to minimize the risk of perforation. In this report, we describe a novel bioptical approach for ARVC diagnosis guided by the identification of right ventricle (RV) affected regions by means of electroanatomical voltage mapping.

Nonischemic Left Ventricular Scar Sporadic or Familial? Screen the Genes, Scan the Mutation Carriers

A 20-year-old soccer player died suddenly while watching a game with friends at home. At annual preparticipation screening, ECG was normal with consequent sport eligibility (Figure 1A). History for juvenile sudden death and hypertrophic cardiomyopathy was reported on the mother’s side of the family. Postmortem examination of the heart showed normal dimensions (weight, 347 g; wall thicknesses of left ventricle [LV] and septum 13 mm and right ventricle [RV], 3 mm), in the absence of aneurysms or chamber dilatation; a subepicardial scar-like grey rim was evident in the anterolateral and posterior LV free wall and in the septum (Figure 1B). Coronary arteries had a normal origin and course, with patent lumen. Histological examination revealed extensive subepicardial and intramural fibrous replacement with scarce fatty tissue infiltration, involving the entire LV circumference and the septum (Figure 1C). Right ventricular involvement was only focally detected, in the anterior wall. The features were in keeping with either chronic myocarditis or left-dominant arrhythmogenic cardiomyopathy (AC). Figure 1. A , Basal 12-lead ECG at annual preparticipation screening showing normal findings. B , Transverse section of the heart showing a subepicardial scar-like grey rim in the anterolateral and posterior LV free wall and in the septum, in the absence of wall thinning and aneurysm formation. …

Plzf as a Candidate Gene Predisposing the Spontaneously Hypertensive Rat to Hypertension, Left Ventricular Hypertrophy, and Interstitial Fibrosis

BACKGROUND The spontaneously hypertensive rat (SHR) is the most widely used model of essential hypertension and is susceptible to left ventricular hypertrophy (LVH) and myocardial fibrosis. Recently, a quantitative trait locus (QTL) that influences heart interstitial fibrosis was mapped to chromosome 8. Our aim was to dissect the genetic basis of this QTL(s) predisposing SHR to hypertension, LVH, and interstitial fibrosis. METHODS Hemodynamic and histomorphometric analyses were performed in genetically defined SHR.PD-chr.8 minimal congenic strain (PD5 subline) rats. RESULTS The differential segment, genetically isolated within the PD5 subline, spans 788kb and contains 7 genes, including the promyelocytic leukemia zinc finger (Plzf) gene that has been implicated in hypertrophy and cardiac fibrosis. Mutant Plzf allele contains a 2,964-bp deletion in intron 2. The PD5 congenic strain, when compared with the SHR, showed significantly reduced systolic blood pressure by approximately 15mm Hg (P = 0.002), amelioration of LVH (0.23±0.02 vs. 0.39±0.02g/100g body weight; P < 0.00001), and reduced interstitial fibrosis (17,478±1,035 vs. 41,530±3,499 μm(2); P < 0.0001). The extent of amelioration of LVH and interstitial fibrosis was disproportionate to blood pressure decrease in congenic rats, suggesting an important role for genetic factors. Cardiac expression of Plzf was significantly reduced in prehypertensive (8 and 21 days) congenic animals compared with controls. CONCLUSIONS These results provide compelling evidence of a significant role for genetic factors in regulating blood pressure, LVH, and cardiac fibrosis and identify mutant Plzf as a prominent candidate gene.