Contribution of MRI in the evaluation of ischemic heart diseases

The high spatial and temporal resolution of MRI provides accurate identification of left ventricular endocardial and epicardial contours. Cine-MRI allows reliable and reproducible measurements of end-systolic and end-diastolic volumes, ejection fraction and left ventricular mass. These measurements are not based on any geometrical hypothesis and so remain valid in presence of ventricular deformation as observed after myocardial infarctions. The value of cine-MRI has been demonstrated in ischaemic heart disease for the study of regional left ventricular function, by analysis of left ventricular segmental function and systolic thickening of the myocardial walls. Cine-MRI may also be performed during pharmacological stress. In coronary patients without ventricular dysfunction at rest, stress cine-MRI enables detection of segmental wall motion abnormalities or reduction of systolic thickening in potentially ischaemic territories. Cine-MRI may contribute to be study of myocardial viability. Regional myocardial perfusion may also be assessed using the rapid sequences of imaging and contrast agents opacifying the intravascular compartment. In coronary patient, underperfused regions may there by be detected. The most rapid imaging techniques enable visualisation of the proximal segments of the coronary arteries and the measurement of blood velocity in the coronary arteries and the calculation of coronary reserve. Simultaneous analysis under basal conditions and after pharmacological stress of global and segmental left ventricular function and of myocardial perfusion, associated with the possibility of imaging the proximal coronary arteries and of measuring the velocity of coronary flow, makes MRI a complete non-invasive method of evaluating patients with ischaemic heart disease.     

Purification and cDNA cloning of porcine brain GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha1-->6fucosyltransferase

GDP-L-Fuc:N-acetyl-beta-D-glucosaminide alpha1-->6fucosyltransferase (alpha1-6FucT; EC 2.4.1.68), which catalyzes the transfer of fucose from GDP-Fuc to N-linked type complex glycopeptides, was purified from a Triton X-100 extract of porcine brain microsomes. The purification procedures included sequential affinity chromatographies on GlcNAcbeta1-2Manalpha1-6(GlcNAcbeta1-2Manalpha1- 2)Manbeta1-4GlcNAcbet a1-4GlcNAc-Asn-Sepharose 4B and synthetic GDP-hexanolamine-Sepharose 4B columns. The enzyme was recovered in a 12% final yield with a 440, 000-fold increase in specific activity. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave a major band corresponding to an apparent molecular mass of 58 kDa. The alpha1-6FucT has 575 amino acids and no putative N-glycosylation sites. The cDNA was cloned in to pSVK3 and was then transiently transfected into COS-1 cells. alpha1-6FucT activity was found to be high in the transfected cells, as compared with non- or mock-transfected cells. Northern blotting analyses of rat adult tissues showed that alpha1-6FucT was highly expressed in brain. No sequence homology was found with other previously cloned fucosyltransferases, but the enzyme appears to be a type II transmembrane protein like the other glycosyltransferases.     

High-performance subquarter-micrometer gate CMOS technology

A single phosphorous-doped poly(n⁺)-Si gate, a 3.5-nm-thick gate oxide, and a retrograde twin-well structure with trench isolation are used in the devices considered. Latchup holding voltages exceed 8 V. The transconductances of 0.22-μm-gate-length n and p MOSFETs are 450 and 330 mS/mm, respectively, and unloaded ring oscillator delays are 36 ps at 2 V. A static-type 1/2 divider utilizing nMOSFETs of 0.16-μm gate length and pMOSFETs of 0.22-μm gate length achieved a maximum operating frequency of 1.3 GHz and power of 5.6 mW at a supply voltage of 2 V     

Effects of Ga content and reaction pressure upon the aromatization of propane over H–Ga–Al-bimetallosilicate catalysts

Aromatization of propane has been investigated at 540 °C in a reaction pressure range up to 0.686 MPaG over MFI-type H–Ga–Al-bimetallosilicates having various Ga/(Ga + Al) atomic ratios but a constant Si/(Ga + Al) ratio of 15. Both the propane conversion and the aromatic selectivity increased with increasing the Ga/(Ga + Al) ratio up to 0.25. Further increase in the Ga content decreased the propane conversion, although the aromatic selectivity increased. Of the catalysts examined, the H–Ga–Al-bimetallosilicate sample having the Ga/(Ga + Al) ratio of 0.25 showed the highest performance for propane aromatization. The effect of reaction pressure was investigated using this catalyst. With increasing the reaction pressure, the propane conversion increased, but the aromatic selectivity decreased. The reaction pressure was also found to strongly influence the cracking activity and the deactivation rate of the catalyst. From the analysis of the gaseous products, it was concluded that the aromatization reaction was suppressed under high reaction pressure conditions because of the formation of methane and ethane by protolytic cracking and hydrogen transfer from aromatic precursors to olefinic intermediates.     

Structure and chemistry of grain boundaries in SiO2-doped TZP

The addition of glass phase can control the grain boundary structure and hence the mechanical properties of tetragonal zirconia polycrystals (TZP). To reveal the effect of the glass dopant on the high-temperature deformation behavior of TZP, SiO₂-doped TZP, (SiO₂—Al₂O₃)-doped TZP, (SiO₂—MgO)-doped TZP and undoped TZP were prepared and their grain boundary structure, chemical composition and chemical bonding state were investigated by high resolution electron microscopy ,HREM), energy dispersive X-ray spectroscopy ,EDS) and electron energy loss spectroscopy (EELS) using a field-emission-type transmission electron microscope (FE-TEM). It was found that no amorphous film was formed along the grain boundaries in any of the specimens examined, but amorphous pockets formed at multiple grain boundary junctions in three kinds of glass-doped specimens. In the glass-doped specimens, the segregation of yttrium, silicon and the added metal ions (Al³¹ or Mg²¹) was observed over a width of several nm across the grain boundaries. The addition of pure SiO₂ much enhanced the ductility in TZP, although further addition of a small amount of Al₂O₃ or MgO to SiO₂ phase resulted in a marked reduction in the tensile ductility of SiO₂-doped TZP. EELS measurements and molecular orbital (MO) calculations using a cluster model revealed that the ductility of TZP was related to the bond overlap population (BOP) at the grain boundaries, which was influenced by the kinds of segregated dopants. That is, the presence of Si⁴¹ increases the BOP, strengthening the grain boundary bonding strength and thus preventing cavity formation, but Al³¹ and Mg²¹ decrease the BOP, enhancing the grain boundary cavitation and thus reducing the ductility. Furthermore, the dynamic behavior of SiO₂ in TZP was observed using a TEM in situ heating technique, and the results supported the fact that that Si segregates along the grain boundaries.     

Growth and toxin production of proteolytic Clostridium botulinum in aseptically steamed rice products at pH 4.6 to 6.8, packed under modified atmosphere, using a deoxidant pack

Demand for aseptically steamed rice products has been increasing rapidly in Japan over the past 10 years. In our previous study, we showed that proteolytic Clostridium botulinum produce toxins in steamed rice products packaged under a modified atmosphere of < or =0.3% oxygen. In the present study, we examined the effect of pH to control botulism risk in steamed rice products packaged under modified atmosphere (5% CO2 and 95% N2 as the balance) with the inclusion of a deoxidant pack to produce an oxygen concentration of < or =0.3%. A mixture of 10 strains of proteolytic C. botulinum (5 type A strains and 5 type B strains) was inoculated into steamed rice products at pH values between 4.6 and 6.8 prior to packaging. All samples were stored at 30 degrees C for 24 weeks. Samples at higher pH showed earlier starts of neurotoxin production. Neurotoxin was detected after 2 weeks of incubation in samples at pH 5.4 or above, whereas it took 4 weeks for the toxin to be detected in samples at pH 5.2 to 5.3 and 12 weeks in samples at pH 5.0 to 5.1. In samples at pH 4.9 or below, no toxin was detected during the experimental period. Apparent sample spoilage did not occur before C. botulinum produced neurotoxin in most of the samples. Based on these results, we conclude that aseptically steamed rice products must be packaged at pH 4.9 or below under modified atmosphere containing < or =0.3% oxygen, with the inclusion of a deoxidant pack.     

InGaAs quantum dots formed in tetrahedral-shaped recesses on GaAs (111)B grown by metalorganic chemical vapor deposition

Novel semiconductor quantum dots (QDs), grown in tetrahedral-shaped recesses (TSRs) formed on a (111)B GaAs substrate, are described from both material science and device application points of view. After explaining the fabrication procedure for TSRs, growth of InGaAs QDs and their optical properties are explained. It is revealed that an InGaAs QD of indium-rich chemical composition is formed spontaneously at the bottom of each TSR. The mechanism of the QD formation is discussed in detail. It is proved from magneto-photoluminescence that the QDs actually have optical properties peculiar to zero-dimensional confinement. Several experimental results indicating excellent growth controllability of the QDs are presented. Finally, recent challenges to apply the QDs to electronic memory devices are reported. Two kinds of devices, where the position of individual QD is artificially controlled, are proposed for the first time and the preliminary experimental results are explained.     

Sensory requirements for noncontact penile erection in the rat.

Physical contact is not necessary for male rats to display penile erection when placed in the vicinity of females in estrus (noncontact erection, NCE). The modality and reception of sensory stimuli for the induction of NCE were analyzed. Olfactory bulbectomy eliminated NCE, and destruction of olfactory mucosa by zinc sulfate solution caused a significant suppression of NCE, whereas removal of the vomeronasal organ had no effect. Fresh urine collected from estrous females, but not fresh feces, induced NCE. Neither devocalization of estrous females by cutting the inferior laryngeal nerve nor deprivation of visual cues by placing an opaque barrier between the subjects and stimulus females disrupted NCE. The results indicate that olfactory cues emitted by estrous females induce NCE via the olfactory epithelium. Contrary to what had been suggested by previous experiments, vomeronasal inputs are not indispensable for the induction of NCE. (PsycINFO Database Record (c) 2010 APA, all rights reserved)