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Articles by A Klein
Total Records ( 2 ) for A Klein
  Z. B Popovic , C Puntawangkoon , D Verhaert , N Greenberg , A Klein , J. D Thomas and R. A. Grimm
  Background—

It is unknown whether longitudinal rotation (LR), often seen in cardiac resynchronization therapy candidates, may affect mitral annular early diastolic (E') velocities and tricuspid annular motion. We assessed whether (1) LR affects the amplitude and timing of septal and lateral mitral annular E' velocities and tricuspid annular systolic and E' velocities and (2) if systolic strain heterogeneity seen in cardiac resynchronization therapy patients with LR extends into diastole.

Methods and Results—

Ninety-nine cardiac resynchronization therapy candidates with suitable baseline echocardiograms were identified. Early diastolic (E') and systolic myocardial velocities of the tricuspid annulus and E' velocities of the septal and lateral part of the mitral annulus were analyzed from tissue Doppler images. Longitudinal rotation and basal systolic and diastolic strain rates were analyzed by speckle-tracking. LR correlated with lateral mitral annular E' (r=0.45, P<0.001), tricuspid annular E' (r=–0.3, P=0.003), and with a difference between septal and lateral mitral annular E' velocities (r=–0.49, P<0.001) but not with septal mitral annular E' velocity. LR also correlated with tricuspid annular systolic velocity (r=0.60, P<0.001). After categorizing the patients according to the quartiles of their LR, we showed that with decreasing quartile number, heterogeneity of systolic (P=0.003) but not diastolic (P>0.1) strain rates increased.

Conclusions—

LR direction and magnitude correlates with the amplitude of, and relative differences between, diastolic velocities of tricuspid, lateral mitral, and septal mitral annulus, which are a cornerstone of diastolic function assessment. LR is associated with systolic but not with diastolic regional heterogeneity.

  W Weidemann , C Klukas , A Klein , A Simm , F Schreiber and R. Horstkorte
 

Sialic acids are widely expressed as terminal carbohydrates on glycoconjugates of eukaryotic cells. They are involved in a variety of cellular functions, such as cell adhesion or signal recognition. The key enzyme of sialic acid biosynthesis is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase (GNE), which catalyzes the first two steps of sialic acid biosynthesis in the cytosol. Inactivation of GNE causes early embryonic lethality. In this study, we analyzed wild-type and GNE-deficient embryonic stem cells from mice. We found for the first time that proliferation is directly correlated with GNE-expression and the cellular sialic acid concentration. Furthermore, we identified growth-related genes that are differentially expressed in GNE-deficient embryonic stem cells compared to wild-type embryonic stem cells.

 
 
 
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