4D-Analysis of Left Ventricular Heart Cycle Using Procrustes Motion Analysis

The aim of this study is to investigate human left ventricular heart morphological changes in time among 17 healthy subjects. Preliminarily, 2 patients with volumetric overload due to aortic insufficiency were added to our analyses. We propose a special strategy to compare the shape, orientation and size of cardiac cycle’s morphological trajectories in time. We used 3D data obtained by Speckle Tracking Echocardiography in order to detect semi-automated and homologous landmarks clouds as proxies of left ventricular heart morphology. An extended Geometric Morphometrics toolkit in order to distinguish between intra- and inter-individual shape variations was used. Shape of trajectories with inter-individual variation were compared under the assumption that trajectories attributes, estimated at electrophysiologically homologous times are expressions of left ventricular heart function. We found that shape analysis as commonly applied in Geometric Morphometrics studies fails in identifying a proper morpho-space to compare the shape of morphological trajectories in time. To overcome this problem, we performed a special type of Riemannian Parallel Transport, called “linear shift”. Whereas the two patients with aortic insufficiency were not differentiated in the static shape analysis from the healthy subjects, they set apart significantly in the analyses of motion trajectory’s shape and orientation. We found that in healthy subjects, the variations due to inter-individual morphological differences were not related to shape and orientation of morphological trajectories. Principal Component Analysis showed that volumetric contraction, torsion and twist are differently distributed on different axes. Moreover, global shape change appeared to be more correlated with endocardial shape change than with the epicardial one. Finally, the total shape variation occurring among different subjects was significantly larger than that observable across properly defined morphological trajectories.     

Is formalin fixation and ethanol preservation able to influence in geometric morphometric analysis? Fishes as a case study

Geometric morphometric analysis has increased in the recent years, turning into a powerful tool to explore shape and size variation. Several biological studies use specimens that have been through some kind of preservation, mainly formalin preservation, commonly used in biological collections. This study analyzed the effect of preservation in shape on two fish species: Eucinostomus argenteus and Pomadasys corvinaerformis. Twenty-nine individuals of E. argenteus and twenty-five of P. corvinaeformis were collected, photographed twice, preserved in 10 % formalin for 1 week, and then transferred to 70 % ethanol for 83 days. We evaluated three levels of error: (1) error of landmark digitalization, (2) error of taking the picture and storage in JPEG format, and (3) the formalin and ethanol fixation error using Procrustes ANOVA, Discriminant Analysis, and Principal Component Analysis. Significant difference between treatments was observed on both species with Procrustes ANOVA and Discriminant Analysis. In addition, Principal Component Analysis showed a separation between groups of treatment on both species. These results represent the first evidence of preservation effects in studies of geometric morphometrics and show that according to the statistical test utilized, the fixation could affect the shape variations in different ways and could lead the researcher to false results or wrong conclusions. Other methods to explore the shape variation of organisms previously fixed should be tested in order to assess their influence in geometric mophrometric studies.     

Parallel variation among populations in the shell morphology between sympatric native and invasive aquatic snails

A phenotypic response, either plastic or evolved, is often required for successful invasion of novel environments. Populations of the invasive snail Potamopyrgus antipodarum have colonized a wide range of environments in the western U. S. since 1985, but the extent of plastic adjustment and evolved adaptation to local environments is largely unknown. We examined variation in shell morphology among four sites in the Snake River, Idaho, including both still-water and free-flowing river habitats and compared the variation to that of a native snail (Pyrgulopsis robusta) using geometric morphometric techniques. Using Generalized Procrustes analysis, we tested for phenotypic responses by determining (1) whether Po. antipodarum from the four locations differed in shell morphology, and (2) whether these snails exhibited corresponding shell shape variation with sympatric populations of a native snail. Both native and invasive snails exhibited similar variation in shell morphology across three of the four sites. The Canonical Variate assignment test grouped 85 % of both snail species to their rightful sample site. In addition, the Principal Component Analysis displayed similar patterns of shell variation across the four sites, indicating parallel variation in shell shape. For three of the four sites, both the native and invasive snails exhibited differences in shell shape consistent with water flow variation (still-water versus fast free-flowing river). Taken together, these results suggest that the shell shape of the invasive snail has changed either through plasticity or evolution, and that both native and invasive snail populations responded to local environmental conditions in a similar manner.     

IDENTIFYING ASSESSOR DIFFERENCES IN WEIGHTING THE UNDERLYING SENSORY DIMENSIONS

In a previous paper Kunert and Qannari (1999) discussed a simple alternative to Generalized Procrustes Analysis to analyze data derived from a sensory profiling study. After simple pretreatments of the individual data matrices, they propose to merge the data sets together and undergo Principal Components Analysis of the matrix thus formed. On the basis of two data sets, it was shown that the results slightly differ from those obtained by means of Generalized Procrustes Analysis.
In this paper we give a mathematical justification to this approach by relating it to a statistical regression model. Furthermore, we obtain additional information from this method concerning the dimensions used by the assessors as well as the contribution of each assessor to the determination of these dimensions. This information may be useful to characterize the performance of the assessors and single out those assessors who downweight or overweight some dimensions. In particular, those assessors who overweight the last dimensions should arouse suspicion regarding their performance as, in general, the last dimensions in a principal components analysis are deemed to reflect random fluctuations.     

Characterization of the age-dependent shape of the pediatric thoracic spine and vertebrae using generalized procrustes analysis

Generalized Procrustes Analysis (GPA) is a superimposition method used to generate size-invariant distributions of homologous landmark points. Several studies have used GPA to assess the three-dimensional (3D) shapes of or to evaluate sex-related differences in the human brain, skull, rib cage, pelvis and lower limbs. Previous studies of the pediatric thoracic vertebrae suggest that they may undergo changes in shape as a result of normative growth. This study uses GPA and second order polynomial equations to model growth and age- and sex-related changes in shape of the pediatric thoracic spine. We present a thorough analysis of the normative 3D shape, size, and orientation of the pediatric thoracic spine and vertebrae as well as equations which can be used to generate models of the thoracic spine and vertebrae for any age between 1 and 19 years. Such models could be used to create more accurate 3D reconstructions of the thoracic spine, generate improved age-specific geometries for finite element models (FEMs) and used to assist clinicians with patient-specific planning and surgical interventions for spine deformity.     

Using biplots to interpret gene expression patterns in plants

Plant biologists in fields of ecology, evolution, genetics and breeding frequently use multivariate methods. This paper illustrates Principal Component Analysis (PCA) and Gabriel's biplot as applied to microarray expression data from plant pathology experiments.     

MYBPC3 polymorphism is a modifier for expression of cardiac hypertrophy in patients with hypertrophic cardiomyopathy

Clinical phenotype of hypertrophic cardiomyopathy exhibits significant inter- and intra-familial heterogeneities. To test if MYBPC3 polymorphism could modify the expression of cardiac hypertrophy, 226 patients with hypertrophic cardiomyopathy and 226 age- and sex-matched controls were recruited according to the diagnostic criteria of WHO. Genotyping was completed by using PCR, restrictive enzyme digestion, and sequencing. Three polymorphisms of MYBPC3 were studied, only the GG genotype at 18443 in exon 30 associated with thicker left ventricular wall (25.2+/-5.9 mm) in patient group, not the AA and AG genotypes (19.0+/-5.0mm, P<0.001). After multiple regression analysis for adjustment of age and sex, the association remained. No difference was found in the genotype distribution between control and patients. Our results point out that GG genotype of MYBPC3 might be a genetic risk factor for the expression of cardiac hypertrophic phenotype in the patients with hypertrophic cardiomyopathy.     

Left ventricular hypertrophy induced by abdominal aortic banding and its prevention by angiotensin receptor blocker telmisartan—a proteomic analysis

Cardiac hypertrophy is frequently caused by pressure overload (i.e., high blood pressure or hypertension) and can lead to heart failure. The major objective of the present study was to investigate the proteomic changes in response to the development of left ventricular hypertrophy (LVH) induced by abdominal aortic banding (AB) and its prevention by antihypertensive treatment with angiotensin II receptor blocker (ARB) telmisartan. One week after AB and Sham surgery, rats were assigned into three groups: SHAM–control, aortic banding without treatment (AB–Ctrl) and aortic banding with telmisartan treatment (AB–Telmi; 5mg/kg/day for 8 weeks). Echocardiography, hemodynamics, and pathology were performed to assess LVH. Left ventricular myocardium was sampled. The analysis of proteomic proteins from myocardium was performed by two-dimensional gel electrophoresis and MALDI–TOF–MS. In AB–Ctrl, heart rate, systolic arterial blood pressure, diastolic blood pressure, left ventricular end systolic pressure, interventricular septal thickness at diastole, posterior wall thickness in diastole, heart weight (HW) and HW/body weight (BW) were increased, indicating that both hypertension and LVH developed. Telmisartan prevented hypertension and LVH. Concurrently, among numerous proteins, there were 17 that were differentially expressed among hypertrophic hearts, normal hearts, and the hearts where hypertrophic response was suppressed by ARB treatment. Primarily, proteins involved in cell structure, metabolism, stress and signal transduction exhibited up-regulations in LVH, providing cellular and molecular mechanism for hypertrophic development. These changes were prevented or greatly attenuated by telmisartan regimen. Interestingly, antioxidative-related heat shock protein 2 was detected neither in SHAM–Ctrl nor in AB–Ctrl, but in AB–Telmi. LVH is accompanied by series changes of protein expression. Both LVH and proteomic changes can be prevented by blockade of renin–angiotensin system with telmisartan. These protein alterations may constitute mechanistic pathways leading to hypertrophy development and experimental targets for novel therapeutic strategy.     

A molecular basis for familial hypertrophic cardiomyopathy: an alpha/beta cardiac myosin heavy chain hybrid gene

An alpha/beta cardiac myosin heavy chain (MHC) hybrid gene is coinherited with familial hypertrophic cardiomyopathy (FHC) in one kindred. FHC is a disease of the heart muscle characterized by a thickening of the left ventricular wall with myocyte and myofibrillar disarray that is inherited as an autosomal dominant trait. We demonstrate here and in the accompanying article that the cardiac MHC genes, which encode integral myofibrillar components, are mutated in all affected individuals from two unrelated families with FHC. In one kindred, an unequal crossover event during meiosis may have produced the alpha/beta cardiac MHC hybrid gene that is present in affected individuals. We conclude that mutations in the cardiac MHC genes can cause FHC.     

A novel mouse model of X-linked cardiac hypertrophy

We recovered a novel mouse mutant exhibiting neonatal lethality associated with severe fetal cardiac hypertrophy and with some adult mice dying suddenly with left ventricular hypertrophic cardiomyopathy. Using Doppler echocardiography, we screened surviving adult mice in this mutant line for cardiac hypertrophy. Cardiac dimensions were obtained either from two-dimensional images collected using a novel ECG-gated ultra-high-frequency ultrasound system or by traditional M-mode imaging on a clinical ultrasound system. These analyses identified, among the littermates, two populations of mice: those with apparent cardiac hypertrophy with hypercontractile function characterized by ejection fraction of 75-80%, and normal littermates with ejection fraction of 53-55%. Analysis of the ECG-gated two-dimensional cines indicated that the hypertrophy was of the nonobstructive type. Further analysis of heart-to-body weight ratio confirmed the ultrasound diagnosis of left ventricular hypertrophic cardiomyopathy. Histopathology showed increased ventricular wall thickness, enlarged myocyte size, and mild myofiber disarray. Ultrastructural analysis by electron microscopy revealed mitochondria hyperproliferation and dilated sarcoplasmic reticulum. Genome scanning using microsatellite DNA markers mapped the mutation to the X chromosome. DNA sequencing showed no mutations in the coding regions of several candidate genes on the X chromosome, including several known to be associated with left ventricular hypertrophic cardiomyopathy. These findings suggest that this mouse line may harbor a mutation in a novel gene causing X-linked cardiomyopathy.     

Interspecific comparison of growth and shape within Diapterus (Gerreidae: Perciformes) using geometric morphometrics

Morphometric analyses can generate useful information to solve taxonomic problems by direct comparison of each species representative’s shape or by analyzing its growth patterns. In this study, growth patterns and shape variation of the four fish species belonging to the genus Diapterus (Gerreidae) were analyzed using geometric morphometrics. We examined 287 specimens, D. auratus (n = 65), D. aureolus (n = 76), D. brevirostris (n = 87) and D. rhombeus (n = 59). For the exploration of growth trajectories of each species, the standard length was used as a size measurement, and the Procrustes distance as a morphological variation measurement. We also compared averages of the morphological change direction within each species through a pairwise comparison between vector angles. These analyses were also used to select those fishes whose increase in size did not lead to a significant change in Procrustes distance. Once this subsample was selected, the body shapes of the four species were compared using Canonical variate Analysis and Multivariate Analysis of Variance. Diapterus aureolus showed the most different morphological trajectory and the most divergent vector within the genus. An average of 93% of correct classification was estimated from Mahalanobis distances. The Canonical Variate Analysis generated three statistically significant canonical variates (p < 0.001) and indicated that D. auratus, D. brevirostris, and D. rhombeus presented a more related shape between them than D. aureolus, as indicated in previous studies. In this context, we considered the shape and growth of D. aureolus with regard to its congeners can be an important element for suggesting a taxonomic rearrangement. However, our interpretation should be supported by phylogenetic analysis. Based in our study, we suggest that trajectories analyses can be directly used in morphometric comparisons to detect those specimens affected by allometry.     

Polymorphism of the angiotensin-converting enzyme gene in cardiovascular pathology

The aim of the study was to investigate influence of polymorphism of angiotensin-converting enzyme (ACE) gene on peculiarities of clinical process of such cardiovascular pathology as hypertrophic cardiomyopathy, coronary arterial disease and arterial hypertension. The polymorphism of ACE gene was studied in 98 patients: 38 with hypertrophic cardiomyopathy, 35 with coronary arterial disease and 25 with arterial hypertension. Nuclear DNA was extracted from blood leukocytes by phenol-chloroform method. Genotypes of ACE gene were determined by polymeraze chain reaction, followed with electrophoresis in agarose gel. It has been established, that I/D polymorphism of ACE gene has important modificative significance in clinical process at the mentioned diseases.     

Cellular and molecular aspects of familial hypertrophic cardiomyopathy caused by mutations in the cardiac troponin I gene

Mutations in the cardiac troponin I (CTnI) gene occur in approximately 5% of families with familial hypertrophic cardiomyopathy (FHC) and 20 mutations in this gene that cause FHC have now been described. The clinical manifestations of CTnI mutations that cause FHC are diverse, ranging from asymptomatic with high life expectancy to severe heart failure and sudden cardiac death. Most of these FHC mutations in CTnI result in cardiac hypertrophy unlike cardiac troponin T FHC mutations. All CTnI FHC mutations investigated in vitro affect the physiological function of CTnI, but other factors such as environmental or genetic factors (other genes that may affect the CTnI gene) are likely to be involved in influencing the severity of the phenotype produced by these mutations, since the distribution of hypertrophy among affected individuals varies within and between families. CTnI mutations mainly alter myocardial performance via changes in the Ca2+ -sensitivity of force development and in some cases alter the muscle relaxation kinetics due to haemodynamic or physical obstructions of blood flow from the left ventricle.