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Imaging of the myelin water fraction (MWF) is conventionally performed using a multi-echo spin-echo sequence. This technique requires long acquisition times and therefore often suffers from a lack of volume coverage. In this work, the application of 3D balanced steady-state free precession (bSSFP) sequences to extract high-resolution myelin water maps is discussed. 相似文献12.
Extent of postmortem pH decline influences meat quality development. To better understand physiological determination of ultimate pH (pHu), we utilized female and castrated male pigs from a line whose selection index includes differentiated pHu. All genotypes of AMP-activated protein kinase γ3 subunit (AMPKγ3) V199I site were present. The mutant 199II genotype increased pHu, but only in castrated males. Genotype affected glycolytic potential (GP), but GP was weakly associated with pHu. A subset of animals was selected based on low (− Gly) and high (+ Gly) residual glycogen content, and compared with AMPKγ3 200Q, which is associated with low pHu. Both + Gly and 200Q muscle contained glycolytic substrate at 24 h; however, 200Q muscle generated low pHu and greater lactate compared to + Gly. Additionally,− Gly and + Gly groups exhibited similar pHu despite a large difference in GP. In conclusion, high GP does not appear to directly impact the extent of postmortem pH decline. 相似文献
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JP Mathis IE Goldberg GC Rossi L Leventhal GW Pasternak 《Canadian Metallurgical Quarterly》1998,63(11):PL 161-PL 166
The presence of pairs of basic amino acids within the sequence of orphanin FQ/nociceptin (OFQ/N) peptide, the endogenous ligand for the ORL1/KOR-3 receptor, has raised the possibility that processing might generate pharmacologically important truncated peptides, including OFQ/N(1-11). OFQ/N(1-11) is pharmacologically active in vivo with a potency comparable to OFQ/N. Several tyrosine-containing analogs of OFQ/N(1-11) have been synthesized and examined for antinociceptive activity. Like OFQ/N(1-11), [Tyr1]OFQ/N(1-11), [Tyr10]OFQ/N(1-11) and [IodoTyr10]OFQ/N(1-11) given supraspinally in mice were antinociceptive in the tailflick assay in mice. The tyrosine analogs showed similar potencies as OFQ/N(1-11) but longer durations of action. This response was readily reversed by the opioid antagonist naloxone despite poor affinities for these analogs at opioid receptors. Another compound, [Tyr11]OFQ/N(1-11) was highly epileptogenic, inducing naloxone-sensitive seizures in greater than 50% of the mice tested at doses comparable to those examined with the other analogs. These results indicate that it is possible to make analgesic OFQ/N(1-11) analogs. The activity of [IodoTyr10]OFQ/N(1-11) suggests that it may prove useful as a radioligand in exploring potential OFQ/N(1-11) binding sites. 相似文献
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A Elbehti-Green HC Au JT Mascarello D Ream-Robinson IE Scheffler 《Canadian Metallurgical Quarterly》1998,213(1-2):133-140
The neurological manifestations of multiple sclerosis (MS) have been considered to result from demyelination of axons with relative preservation of axonal integrity. This concept has been challenged recently by a landmark pathological study, published in the New England Journal of Medicine, which has demonstrated that axonal degeneration is also present. The authors of the study hypothesized that axonal degeneration is the pathological correlate of the irreversible neurological impairment in this disease. However, this hypothesis cannot be reconciled with the clinical results obtained with transcranial applications of AC pulsed electromagnetic fields (EMFs) of picotesla flux density which have shown rapid and sustained improvement of symptoms including normalization of evoked potential responses in patients with chronic progressive or secondary progressive MS without demyelinated areas first undergoing remyelination or transected axons undergoing regeneration. Biochemical studies have shown that MS patients are serotonergically depleted with the extent of cerebral depletion correlating with the degree of motor disability and a chronic progressive course. It is believed that progressive serotonergic neuronal atrophy with synaptic inactivation, not axonal degeneration, are the hallmarks of the disease and that administration of AC pulsed magnetic fields improves symptoms of MS partly through reactivation of serotonergic neurons and amplification of synaptic serotonergic transmission. 相似文献
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Very early in an electronic design cycle the physical buildup of a system, such as bonding method, substrate technology, and number of layers, needs to be chosen before any layout is performed. But when developing high density systems, a huge number of technology choices are available, each having impact on various aspects of the system performance. This paper describes virtual prototyping as a method for systematically analyzing and choosing the suitable buildups and selecting one of them in a cost-performance analysis for implementation and layout. Unlike former design advisors, our method analyzes several possibilities in parallel, allowing for a better design space exploration. The framework is implemented in the Java based tool JavaCAD, JavaCAD manages the different buildups and provides a size/layer count estimation for all first level interconnect/packages on various substrate technologies. It calculates the component footprints, analyzes the routing with as few data as available and allows cost estimation of all feasible buildups. The benefits of our approach are illustrated in the design of a 9:4 satellite switch operating at 2.4 GHz 相似文献
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VG Mel'nikov EA Andreeva LV Vlasova LG Besedina GP Stepanova IaB Be?kin OM Lesniak IE Koshelev 《Canadian Metallurgical Quarterly》1998,(7):21-23
The authors propose a comprehensive approach to laboratory diagnosis of seasonal transmissible infections, based on modern methods permitting etiological deciphering of disease. A universal diagnostic algorithm notably accelerated the laboratory diagnosis due to cutting the period between collection of material from a patient and consecutive screening for antibodies to agents of tick-borne encephalitis, Lyme disease, and California encephalitis. 相似文献