Myocardial velocity gradient as a noninvasively determined index of left ventricular diastolic dysfunction in patients with hypertrophic cardiomyopathy

AbstractObjectivesWe investigated the utility of the peak negative myocardial velocity gradient (MVG) derived from tissue Doppler imaging (TDI) for evaluation of diastolic dysfunction in patients with hypertrophic cardiomyopathy (HCM).BackgroundHypertrophic cardiomyopathy is characterized by impaired diastolic function with abnormal stiffness and prolonged relaxation. However, it remains difficult to evaluate these defects noninvasively.MethodsBoth TDI and conventional echocardiography were performed in 36 patients with HCM and in 47 control subjects. Left ventricular (LV) pressure was measured simultaneously in all HCM patients and in 26 controls.ResultsThe peak negative MVG occurred soon after the isovolumic relaxation period during the initial phase of rapid filling (auxotonic relaxation). It was significantly smaller in HCM patients than in control subjects (2.32 ± 0.52/s vs. 4.82 ± 1.15/s, p < 0.0001); the cutoff value for differentiation between all HCM patients and 47 normal individuals was determined as 3.2/s. Both the left ventricular end-diastolic pressure (LVEDP) (19.6 ± 6.1 mm Hg vs. 6.5 ± 1.7 mm Hg, p < 0.0001) and the time constant of LV pressure decay during isovolumic diastole (tau) (44.0 ± 6.7 ms vs. 32.1 ± 5.5 ms, p < 0.0001) were increased in HCM patients compared with controls. The peak negative MVG was negatively correlated with both LVEDP (r= −0.75, p < 0.0001) and tau (r= −0.58, p < 0.0001).ConclusionsA reduced peak negative MVG reflects both prolonged relaxation and elevated LVEDP. The peak negative MVG might thus provide a noninvasive index of diastolic function, yielding unique information about auxotonic relaxation in patients with HCM

Generation of rat-induced pluripotent stem cells from a new model of metabolic syndrome.

We recently characterized DahlS.Z-Leprfa/Leprfa (DS/obese) rats, derived from a cross between Dahl salt-sensitive rats and Zucker rats, as a new animal model of metabolic syndrome (MetS). Although the phenotype of DS/obese rats is similar to that of humans with MetS, the pathophysiological and metabolic characteristics in each cell type remain to be clarified. Hence, the establishment of induced pluripotent stem cells (iPSCs) derived from MetS rats is essential for investigations of MetS in vitro. Reports of rat iPSCs (riPSCs), however, are few because of the difficulty of comparing to other rodents such as mouse. Recently, the advantage of using mesenchymal stromal cells (MSCs) as a cell source for generating iPSCs was described. We aimed to establish riPSCs from MSCs in adipose tissues of both DS/obese rats and their lean littermates, DahlS.Z-Lepr+/Lepr+ (DS/lean) rats using lentivirus vectors with only three factors Oct4, Klf4, and Sox2 without c-Myc. The morphology, gene expression profiles, and protein expression of established colonies showed embryonic stem cell (ESCs)-like properties, and the differentiation potential into cells from all three germ layers both in vitro and in vivo (teratomas). Both riPSCs became adipocytes after induction of adipogenesis by insulin, T3, and dexamethasone. Real-time PCR analysis also revealed that both riPSCs and the adipose tissue from DS/obese and DS/lean rats possess similar expression patterns of adipocyte differentiation-related genes. We succeeded in generating riPSCs effectively from MSCs of both DS/obese and DS/lean rats. These riPSCs may well serve as highly effective tools for the investigation of MetS pathophysiology in vitro

Primers for RT-PCR.

<p>Primers for RT-PCR.</p

Primers for real time PCR.

<p>Annealing temperature was 60°C and cycling condition was 42 cycles.</p

Expression of adipocyte differentiation-related genes in adipocytes from riPSCs and from DS/obese and DS/lean rats.

<p>A) Quantitative RT-PCR analysis of peroxisome proliferator-activated receptor γ (<i>Pparγ</i>) and adiponectin mRNAs in adipocytes differentiated from l-riPSCs and o-riPSCs. B) <i>Pparγ</i> and adiponectin mRNA from DS/obese and DS/lean rats. Data are means ± SEM of values from two independent experiments for adipocytes differentiated from riPSCs (<i>n</i> = 4 each; <b>A</b>) and for animals (n = 5 and 4 for DS/lean rats and DS/obese rats, respectively; <b>B</b>). *<i>P</i><0.05 versus DS/lean, **<i>P</i><0.01 versus DS/lean.</p

mRNA expressions.

<p>The expression of mRNAs was analyzed by RT-PCR. A) Introduced four genes (<i>EGFP, Sox2, Klf4 and Oct3/4</i>) were expressed in both o-riPSCs and l-riPSCs, but not in both MSCs. Transgenes (mouse mRNA) were detected only in undifferentiated riPSCs cultured in medium containing Dox. Leptin receptor was not detected in the o-riPSCs, however, it was expressed in thel-riPSCs. B) After differentiation in embryoid bodies (EB), <i>Sox17, SM-22a</i>, and <i>Ncam</i> were clearly demonstrated in both o-riPSCs and l-riPSCs. Introduced genes (<i>Sox2, Klf4</i> and <i>Oct3/4</i>) and Transgenes (mouse mRNA) were not detected in differentiated embryoid bodies (EB) of both o-riPSCs and l-riPSCs.</p

Time schedule of iPSC generation.

<p>The experiment was composed of three main processes. The first process was isolation of MSCs from the adipose tissue of either DS/obese or DS/lean rats. The second process was infection of lentivirus. The final process was the selection of iPSC colonies. The collected MSCs were cultured for about 7days. When the MSCs increased in number, we infected them with a lentiviral vector carrying three mouse reprogramming factors, and termed this time point as day 0. The MSCs were then cultured in medium for 2 days, and the cells were replated on SNL feeder cell layers. Finally, EGFP-positive riPSC colonies were picked up at day 10 and some of clones were selected for further analysis.</p