Myocardial Area (myocardial + area)

Distribution by Scientific Domains

Selected Abstracts

Heart changes in 17-day-old fetuses of diabetic ICR (Institute of Cancer Research) mothers: Improvement with maternal immune stimulation

Juan Claudio Gutierrez
ABSTRACT Maternal diabetes mellitus is associated with increased fetal teratogenesis, including cardiovascular defects. Non-specific maternal immune stimulation with Freund's complete adjuvant (FCA) or interferon gamma (IFN,) has been associated with protection against birth malformations. Using a diabetic mouse model, late-gestation fetal heart and great vessel morphology were analyzed. Four groups of mice were used: non-diabetic females as a control group, hyperglycemic females induced by streptozotocin as a diabetic group, and diabetic females injected either with FCA or IFN,. At day 17 of gestation, females were euthanized and one fetus was arbitrarily selected per litter for fixation and sectioning. Treatment-induced changes in cardiac development were assessed from digital images of serial sections taken at standardized levels in the thorax. One-way parametric and non-parametric ANOVA and ordinal logistic regression were performed to compare the difference among groups (P < 0.05). Maternal hyperglycemia altered morphology of the late-gestation fetal mouse heart by causing ventricular chamber dilation, sectional myocardial reduction, and an increase in transversal aortic area. FCA protected the fetal heart from cavitary dilation in diabetic mothers. FCA and IFN, protected the fetal heart against reduction of myocardial area, and ascending thoracic aorta dilation. Consequences of late gestation heart chamber dilation and myocardial reduction are not yet known. Maternal immune stimulation partially protected against these developmental defects by mechanisms that remain unclear. [source]

Is Left Ventricular Diastolic Thickening Documented During Dobutamine and Pacing Stress Echocardiography Related to Myocardial Ischemia?

An Animal Model Study
Transient increase in diastolic wall thickness (pseudohypertrophy) during pacing stress echocardiography has been reported in normal myocardium. To evaluate the occurrence of pseudohypertrophy and to investigate the contribution of myocardial ischemia on its production during pacing and dobutamine stress echocardiography, we produced a physiologically significant coronary stenosis in 14 open chest dogs. The stenosis in the circumflex artery was measured by quantitative coronary angiography (range: 50% to 89% reduction in luminal diameter), and no resting segmental wallmotion abnormalities were observed by epicardial echocardiography (short-axis, papillary level). In each study, dobutamine (5,40 ,g/kg/min) and pacing (up to 260 beats/min) were performed randomly. Positivity of stress echocardiography tests was quantitatively determined by a significant (P < 0.05) reduction or failure to increase in absolute and percent systolic wall thickening in the myocardial area supplied by the stenotic artery as compared to the left anterior descending (LAD) artery-related areas. Diastolic wall thickness and left ventricular diastolic area were compared before and after each stress test in the circumflex and LAD artery-related regions. Pseudohypertrophy was observed in 57% and 86% of dogs for pacing and dobutamine, respectively, in the circumflex region, and in 50% and 64% in the LAD region. Despite its increased incidence in the circumflex region, the augmented diastolic wall thickness did not correlate with coronary stenosis severity or stress test positivity, but correlated inversely with changes in left ventricular diastolic area. In addition, it correlated directly with changes in heart rate only for pacing. In conclusion, pseudohypertrophy was a frequent finding during pacing and dobutamine stress echocardiography tests but was not related to myocardial ischemia in this animal model. [source]

Stereology of the myocardium in Leontopithecus (Lesson, 1840) callitrichidae , primates

A. Pissinatti
Abstract: Rare morphological features of the Leontopithecus cardiovascular system have been reported in the literature. The samples analyzed in this study came from 33 specimens of Leontopithecus from the collection of the Center of Primatology of Rio de Janeiro-FEEMA (CPRJ-FEEMA). Morphometry and stereological data were obtained from all animals. Adult body weights of L. rosalia were the lowest, the greatest being those of L. chrysopygus caissara; body weights of L. chrysomelas and L. c. chrysopygus were similar and in between those of the two former species. Cardiomyocytes (left ventricular myocardium) were bigger in adults than in infants. The myocardium of L. rosalia showed focal fibrosis, fatty vacuoles, and hyalinization. In L. chrysomelas the myocardium showed areas of fibrosis and presence of mononuclear cells. Fibrosis and areas of congestion were observed in L. c. chrysopygus; areas of disorganization and vascular congestion were found in L. c. caissara. In L. rosalia infants, a greater density of vessels per myocardial area and a greater length density of vessels were observed as compared with those of L. chrysomelas. In adults, L. chrysomelas showed greater density of connective tissue in the myocardium than L. c. chrysopygus and L. c. caissara did. In L. rosalia, cardiomyocyte nuclei had a greater area density than those of the other forms of Leontopithecus. These characteristics may explain the faster development of L. rosalia infants as compared with that of L. chrysomelas and L. c. chrysopygus kept under the same handling conditions at the CPRJ-FEEMA. [source]

Feasibility of complementary spatial modulation of magnetization tagging in the rat heart after manganese injection

J.-N. Hyacinthe
Abstract It has been shown that manganese-enhanced MRI (MEMRI) can safely depict the myocardial area at risk in models of coronary occlusion,reperfusion for at least 2,h after reperfusion. To achieve this, a solution of MnCl2 is injected during coronary occlusion. In this model, the regional function quantification deficit of the stunning phase cannot be assessed before contrast injection using MR tagging. The relaxation effects of manganese (which remains in normal cardiac myocytes for several hours) may alter the tags by increasing tag fading and hence the quality of strain measurement. Therefore, we evaluated the feasibility of cardiac MR tagging after manganese injection in normal rats. Six normal Sprague,Dawley rats were imaged in vivo using complementary spatial modulation of magnetization (C-SPAMM) at 1.5,T, before and 15,min after intraperitoneal injection of MnCl2 solution (,17.5,µmol,kg,1). The contrast-to-noise ratio of the tag pattern increased significantly (P,<,0.001) after injection and remained comparable to the control scan in spite of the higher myocardial relaxation rate caused by the presence of manganese. The measurements of circumferential strain obtained from harmonic phase imaging analysis of the tagged images after MnCl2 injection did not differ significantly from the measurements before injection in the endocardial, mid-wall, and epicardial regions. In particular, the transmural strain gradient was preserved. Thus, our study suggests that MR tagging could be used in combination with MEMRI to study the acute phase of coronary artery disease. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Aortic and ventricular dilation and myocardial reduction in gestation day 17 ICR mouse fetuses of diabetic mothers

J. Claudio Gutierrez
Abstract BACKGROUND: Maternal diabetes mellitus is associated with increased fetal teratogenesis, including cardiovascular defects. Information regarding cardiovascular changes in late-gestation fetal mice, related to maternal hyperglycemia, is not present in the literature. METHODS: Late-gestation fetal heart and great vessel morphology were analyzed in fetuses from control and diabetic mice. Female ICR mice were injected with streptozocin (200 mg/kg IP) prior to mating to induce diabetes (n = 8). Nonhyperglycemic females were used as controls (n = 8). At day 17 of gestation, females were euthanized and one fetus was arbitrarily selected per litter to analyze the heart and great vessels. Six additional fetuses from different litters, showing external malformations (spina bifida and/or exencephaly), were also evaluated from the diabetic group. Fetal thoraxes were processed using routine histopathologic techniques, and 7-,m transversal sections were stained with hematoxylin-eosin. Digital images of sections were made and analyzed using NIH Image J software to compare regional cardiac development. Student's t tests for means were performed to determine differences between groups (p < .05). RESULTS: Maternal hyperglycemia caused a dilation of late-gestation fetal ventricular chambers, a reduction of total ventricular myocardial area, and an increase in transversal ascending thoracic aortic area. Three of six fetuses that displayed external malformations showed an overt cardiac defect, beyond the ventricular and myocardial changes. CONCLUSIONS: Maternal hyperglycemia altered morphology of the late-gestation fetal mouse heart. Postnatal persistence or consequences of late-gestation heart chamber dilation and myocardial reduction are not yet known. Birth Defects Research (Part A) 2007. © 2007 Wiley-Liss, [source]