Of mice and men . . . and broken hearts

Prevalence of Diet Atherogenicity and Coexistence of Lipid Disorders and Arterial Hypertension among 50-year-old Inhabitants of Wroclaw, Poland

OBJECTIVE

The incorrect composition of a diet, its atherogenicity, is conducive to the occurrence of lipid disorders, arterial hypertension (HTN), diabetes, and metabolic syndrome (MetS). The aim of the study was to evaluate the prevalence of incorrect anthropometric and biochemical parameters as well as diet atherogenicity.

METHODS

The study group included 1,520 adults (880 women, 640 men). The nutritional status evaluation was based on respondents' BMI and waist circumference. The diet atherogenicity was estimated using Keys Index (KI) and P/S ratio. Total cholesterol (TCh), LDL cholesterol as well as triglycerides (TG) concentration in blood serum were also evaluated.

RESULTS

In 56.8% of women and 60.8% of men waist circumference exceeded referential values. The diets of 71.4% of women and 87.3% of men were atherogenic. HTN was observed in 64.1% of the study population. Hypercholesterolaemia was found in approximately 72% of the respondents. The increased LDL cholesterol concentration were found in 57.5% of women and 64.5% of men. Abnormal concentration of HDL cholesterol occurred among approximately 20% of respondents. Hypertriglyceridaemia was recognised in 26% of women and 44% of men. In the group of women and men with HTN, mean values, i.e. BMI, waist circumference and TG (with TCh concentration additionally noted in men) were found as significant. Normal lipid profile and arterial pressure values were observed in 6.6% of the population.

CONCLUSIONS

In the diets of men with HTN were observed higher values of KI compared to group without HTN. No significant differences were found in the frequency of occurrence of the analysed parameters either among the group of women with HTN or without it. In the group of men with HTN, the abnormal BMI, waist circumference and TG occurred more frequently.

MR in mouse models of cardiac disease

Transgenic and knockout mice can be used to study the genes and basic mechanisms involved in heart disease, and have therefore assumed a central role in modern cardiac research. MRI and MRS techniques have recently been developed for mice that enable the quantitative or semi-quantitative in vivo assessment of cardiac anatomy, function, perfusion, infarction, Ca(2+) influx, and metabolism. With these techniques, the normal mouse heart has been shown to be well suited as a model of human cardiac disease. The roles of individual genes in normal cardiac physiology have recently been studied by MR, including the role of neuronal nitric oxide synthase in beta-adrenergic stimulation, the roles of the inducible nitric oxide synthase and myoglobin in function, dilation, and energetics, and the role of cardiac troponin I in contractility. Furthermore, with a mouse model of myocardial infarction, the roles of the angiotensin II type 2 receptor, xanthine oxidase inhibitors, blood coagulation factor XIII, and inducible nitric oxide synthase in post-infarct function and remodeling have been further elucidated. Non-invasive in vivo MRI and MRS in mice provide a unique and powerful means for phenotyping genetically engineered mice and can improve our understanding of the roles of specific genes and proteins in cardiac physiology and pathophysiology.

Black blood gradient echo cine magnetic resonance imaging of the mouse heart

A black blood gradient echo sequence for multiphase cardiac MRI of the mouse heart was implemented on a 4.7-T scanner and compared to a conventional bright blood sequence. Black blood was achieved using the double inversion recovery technique. Ten mice were imaged using both the bright and the black blood sequences, and 2 of the mice were additionally imaged using bright and black blood sequences modified to perform myocardial tagging. Manual planimetry of the images was performed by two independent observers to detect the endocardial and epicardial borders and subsequently to compute chamber volumes and myocardial mass. Weight of the excised left ventricle was used as a gold standard for myocardial mass. Bland-Altman analysis demonstrated reduced interobserver variability for the measurement of cardiac volumes using the black blood sequence compared to the bright blood sequence (95% confidence interval was -0.89-0.73 microL for black blood versus -1.86-1.28 microL for bright blood). Also, Bland-Altman analysis showed that the black blood sequence provides improved accuracy for the measurement of myocardial mass compared to the bright blood sequence (average difference between MRI versus weight was 0.9 microg for black blood and -11.2 microg for bright blood, P < 0.01). For myocardial tagging, qualitative assessment demonstrated improved endocardial border definition using the black blood sequence. Black blood cine MRI in mice provides reduced interobserver variability and improved accuracy for the measurement of myocardial volumes and mass compared to the conventional bright blood technique.

Serial MRI evaluation of cardiac structure and function in mice after reperfused myocardial infarction

This study evaluated the utility of cardiac MRI for assessing the impact of myocardial infarction (MI) on cardiac structure and function in mice following reperfused 1- or 2-hr occlusions of the left anterior descending coronary artery (LAD). When assessed 1 day after MI, the left ventricular ejection fraction (LVEF) had declined by more than half, and remained depressed for the duration of the study. Furthermore, MI initiated dramatic increases in both LV end-systolic volume (LVESV) and end-diastolic volume (LVEDV), with a greater than threefold increase in LVESV and a twofold increase in LVEDV by 4 weeks post-MI. Transmural LV wall thickening (WTh) analysis revealed that noninfarcted myocardium in the remote septal region exhibited an early deficit in contractile function after MI that transiently resolved by day 7, only to be followed by a late phase of dysfunction that became fully manifest by day 28 post-MI. In conclusion, MRI allows the serial assessment of cardiac structure and function after MI in mice, with a resolution adequate to document both regional and temporal changes. The application of these imaging techniques in transgenic and knock-out mice will greatly expedite research aimed at defining the functional roles of individual genes in the pathophysiology of LV remodeling (LVR) after reperfused MI.