Comparison of 2D simultaneous multi-slice and 3D GRASE readout schemes for pseudo-continuous arterial spin labeling of cerebral perfusion at 3 T

Objective

In this perfusion magnetic resonance imaging study, the performances of different pseudo-continuous arterial spin labeling (PCASL) sequences were compared: two-dimensional (2D) single-shot readout with simultaneous multislice (SMS), 2D single-shot echo-planar imaging (EPI) and multishot three-dimensional (3D) gradient and spin echo (GRASE) sequences combined with a background-suppression (BS) module.

Materials and methods

Whole-brain PCASL images were acquired from seven healthy volunteers. The performance of each protocol was evaluated by extracting regional cerebral blood flow (rCBF) measures using an inline morphometric segmentation prototype. Image data postprocessing and subsequent statistical analyses enabled comparisons at the regional and sub-regional levels.

Results

The main findings were as follows: (i) Mean global CBF obtained across methods was were highly correlated, and these correlations were significantly higher among the same readout sequences. (ii) Temporal signal-to-noise ratio and gray-matter-to-white-matter CBF ratio were found to be equivalent for all 2D variants but lower than those of 3D-GRASE.

Discussion

Our study demonstrates that the accelerated SMS readout can provide increased acquisition efficiency and/or a higher temporal resolution than conventional 2D and 3D readout sequences. Among all of the methods, 3D-GRASE showed the lowest variability in CBF measurements and thus highest robustness against noise.

     

Theoretical Method to Predict the First Microcracks in a Scarf Joint

In this work, we have calculated the theoretical threshold (F _d) of the first microcracks in the scarf joint. This threshold is particularly important because it marks the end of the elastic behavior of the bonded structure. At this point, the mechanical behavior of the adhesive is nonlinear and becomes dependent on the type of loading applied (dynamic tests, fatigue). Our method takes into account the geometrical variations of the joint as the scarf angle varies. We have used and adapted to our study a theoretical model based on the asymptotic-expansion method. The comparison between the theoretical values and the experimental thresholds determined by strain gauges and acoustic-emission techniques showed that the model accurately forecasts the microcracking of the joint provided that the scarf-angle value is more than 10°. When α is smaller than 10°, the theoretical model can no longer predict the very complex micromechanical behavior at the extremities of the joint, where the sharp ends of the adhesive layer and the metallic adherends coexist and react among themselves.     

Preservation of masculine sexual functions after treatment for abdominal aortic aneurysms

Preserving sexual function is an important objective in the treatment of aneurysms of the abdominal aorta in men. METHOD: Two groups of patients with normal sexual function were operated for aneurysms of the abdominal aorta. In group 1 (n = 22) a small opening in the infra-renal aorta was made for insertion of an aorto-bi-iliac prosthesis; in 4 of them, the aneurysm was not opened but simply excluded. In group 2 (n = 22), the aorta was opened longitudinally for insertion of an aorto-aortic tube. RESULTS: Sexual function was totally abolished after operation in 9% of the patients in group 1 and in 36% of those in group 2. Sexual functions were totally preserved in 50% of the patients in group 1 and in 36% of those in group 2, but the differences were not statistically significant. CONCLUSIONS: 1) It is not always possible to guarantee maintained sexual function after operation for aneurysms of the abdominal aorta and the patients should be advised thereto; 2) aortobi-iliac prostheses with limited opening of the aorta in the upper part of the aneurysm or exclusion of the aneurysm led to a higher rate of preservation than aorto-aortic tubes with total opening of the aneurysm and should be preferred in men with normal sexual function.     

Immunoelectron microscopic visualization of intermediate basic proteins HPI1 and HPI2 in human spermatids and spermatozoa

Problem-solving interactions were observed in 86 families of depressed adolescents and 408 families of non-depressed adolescents. Sequential analyses indicated that mothers of depressed adolescents were more likely than mothers of non-depressed adolescents to increase facilitative behavior in response to adolescent depressive behavior. Additionally, fathers of depressed adolescents were more likely than their counterparts in families of non-depressed adolescents to decrease aggressive behavior subsequent to adolescent depressive behavior. These analyses suggest that parents of depressed adolescents may be inadvertently reinforcing depressive behavior. Decreases in adolescent depressive symptomatology from year 1 to year 2 were not accompanied by changes in family interaction patterns.     

Immunochemical mapping of human lutropin: II. Characterization of two monoclonal antipeptide antibodies reacting with the native beta-subunit

To investigate the epitopes present on the beta-subunit of the human lutropin (hLHbeta) and their topographical relationship at the surface of the molecule, we produced two monoclonal antipeptide antibodies, designated LHP03 and LHP04, capable of binding to the radiolabeled 125I-hLHbeta and directed to the 43-52 and 110-117 regions of the hLHbeta, respectively. Analysis of the accessibility of the epitopes on hLH and on the beta-subunit of human chorionic gonadotropin (hCGbeta), equine LH (eLHbeta) and ovine LH (oLHbeta) indicated that: (i) LHP03 binds to both the free hLHbeta subunit and dimeric hLH whereas LHP04 binds preferentially to the free hLHbeta, (ii) LHP03 recognizes weakly the hCGbeta and oLHbeta in comparison to hLHbeta and (iii) LHP04 binds oLHbeta as well as hLHbeta but does not bind to hCGbeta and eLHbeta. The topographical relationship of epitopes recognized by LHP03 and monoclonal antibodies recognizing dimer specific epitopes on hLH allowed us to localize discontinuous antigenic sites that overlaps or are located outside the hHLbeta(43-52) region. Together, our results demonstrated that the hHLbeta(43-52) portion is accessible on both the free hLHbeta subunit and hLH whereas the COOH-terminal portion, hHLbeta(110-117), is probably buried at the alpha/beta interface of the hormone.     

Peptide mapping characterization by capillary electrophoresis of a human monoclonal anti-Rh(D) antibody produced for clinical study

CE has been employed for peptide mapping characterization of the light chain of a human anti-Rhesus (D) (Rh[D]) antibody presently undergoing clinical evaluation. In the presence of an ion-pairing agent used to increase resolution, reproducible maps were obtained within 55 min after injection of 12 fmol of protein. CE has also been employed as a direct and quick screening tool for purity evaluation of the tryptic peptides obtained from reversed-phase high-performance liquid chromatography (RP-HPLC) prior to sequence analysis. Post-translational modifications of the protein were determined by identification of the cysteine residues implicated in disulfide linkages.     

Modification des propriétés physico-mécaniques et structurales de vases d'estuaire par mélange avec un super absorbant

Recent and current sediments dredged up annually from ports and estuaries represent considerable volumes. The current regulations allow the rejection of muds and sludges in the sea. This procedure will be forbidden in the near future. Therefore, it is necessary to consider a solution of this problem. The use of super absorbent allows an irreversible change of the consistency of these dredged sediments by modifying their structure and their physical and mechanical properties. The new physical state of these materials brings in an immediate gain to transportation and storage, before the treatment or eventual use of these modified sediments.     

Influence de la petrographie sur les caracteristiques physiques et mecaniques de granulats calcaires de lorraine

Limestones with different textures and petrographic composition were chosen for study: polyparies limestones, oolitic limestone and micritic limestone. These rocks are characterized by the study of their porosity and their texture with a Scanning Electron Microscope, by the measurement of the longitudinal elastic waves and of quality index. Uniaxal compression tests were performed, with a servo-controlled testing machine. Aggregates produced from these rocks were tested with Los Angeles and Microdeval machines. The experimental reslts were compared with S.E.M. observations. We compare also surface aspects of the aggregates before and after mechanical test, so fracture pattern of grains.