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131.
H Asahara K Fujisawa T Kobata T Hasunuma T Maeda M Asanuma N Ogawa H Inoue T Sumida K Nishioka 《Canadian Metallurgical Quarterly》1997,40(5):912-918
Green fluorescent protein (GFP) is increasingly being used in plant biology from the cellular level to whole plant level. At the cellular level, GFP is being used as an in vivo reporter to assess frequency of transient and stable transformation. GFP has also proven to be an invaluable tool in monitoring trafficking and subcellular localization of protein. At the organ level and up, many exciting applications are rapidly emerging. The development of brighter GFP mutants with more robust folding properties has enabled better macroscopic visualization of GFP in whole leaves and plants. One interesting example has been the use of GFP to monitor virus movement in and among whole plants. GFP is also emerging as a powerful tool to monitor transgene movement and transgenic plants in the field. In a proof-of-concept study, tobacco was transformed with a modified version of the GFP gene controlled by a constitutive (35S) promoter. GFP expression in progeny plants ranged from 0% to 0.5%, and approximately 0.1% GFP was the minimal amount needed for unambiguous macroscopic detection. GFP is the first truly in vivo reporter system useful in whole plants, and we project its usefulness will increase even further as better forms of GFP genes become available. 相似文献
132.
BACKGROUND: The effect of topical corticosteroids after excimer laser photorefractive keratectomy (PRK) remains a matter of some controversy. Refractive effects may be different according to the amount of myopia and timing of instillation. METHODS: Two groups of patients were studied: Study A consisted of 215 eyes (128 patients) with PRK (mean baseline myopia, -6.53 +/- 2.22 D) that received no corticosteroids (No Corticosteroid Group) unless significant regression or corneal haze appeared (Delayed Corticosteroid Group), and in Study B, we randomly assigned eyes to the Initial Corticosteroid Group (mean baseline myopia, -6.39 +/- 1.84 D) or the No/delayed Corticosteroid Group (mean baseline myopia -5.78 +/- 2.02 D). Clinical results after PRK for low-to-moderate and high myopia were compared. RESULTS: In the first group, 70.9% (73 eyes) of moderately myopic eyes (mean, -4.56 +/- 1.10 D) belonged to the No Corticosteroid Group that had a mean refraction of -5.39 +/- 1.77 D. Delayed Corticosteroid Group eyes were more myopic (mean, -7.52 +/- 2.10 D), and showed more severe haze than those in the No Corticosteroid Group. In study B, only in high myopes with more than -6.00 D (mean, -7.76 +/- 1.15 D) did refraction and corneal haze outcomes show significant difference between the Initial Corticosteroid Group and the No/delayed Corticosteroid Group. CONCLUSIONS: The effects of topical corticosteroids after PRK were less in moderate myopes compared to high myopes. Delayed instillation of corticosteroids did not reverse the regression or haze whereas initial instillation showed a beneficial effect on high myopes but not on moderate myopes. 相似文献
133.
Neurobiological research in schizophrenia has been hampered by several confounding factors such as the heterogeneity of the illness and the paucity of biological markers. Recent progress in research methods, however, has enabled the improvement in our understanding its pathophysiology. This paper reviews recent neurochemical investigations of schizophrenia and its animal models which were conducted in Japan in the last decade. The research areas reviewed are (i) monoamine and their metabolites in body fluids, (ii) phospholipids and prostaglandins, (iii) neurochemistry in autopsy brains, (iv) immunological measures, (v) magnetic resonance spectroscopy, (vi) regional cerebral blood flows (rCBF), (vii) molecular genetics, and (viii) animal models. It is worth noting that there exist abnormalities of amino acidergic (glutamatergic and GABAergic) neurotransmission as well as monoaminergic (dopaminergic and serotonergic) one in postmortem schizophrenic brains. These abnormalities and also the findings of altered rCBF indicate the existence of disturbed neuronal circuits that contribute to the diverse symptoms of schizophrenia. Also, dysfunction of membrane phospholipids derived from studies on magnetic resonance spectroscopy may underlie negative symptoms in schizophrenia. Given that schizophrenia is considered to comprise a group of disorders with a diverse heterogeneity of etiologies, research in the next decade is expected to identify putative genes that are involved in vulnerability to schizophrenic phenotype. 相似文献
134.
K Senior 《Canadian Metallurgical Quarterly》1997,3(12):528-532
As we uncover the physiological and molecular mechanisms behind human reproduction, we gain the potential to exert more control over our reproductive capabilities. In the past two decades, the prospects for 'infertile' women to bear children, or 'sterile' men to father them, have improved dramatically; recently, women have given birth in their sixties, well beyond their natural menopause. Thanks to developments in contraception, couples can now enjoy an active sex-life without a significant risk of pregnancy, and more accurately control the size and timing of their families. But these new freedoms have a price: they also have the potential to cause demographic distortions, medical harm to individuals and abuse of human rights. 相似文献
135.
136.
K Giesen T Hummel A Stollewerk S Harrison A Travers C Kl?mbt 《Canadian Metallurgical Quarterly》1997,124(12):2307-2316
Two classes of glial cells are found in the embryonic Drosophila CNS, midline glial cells and lateral glial cells. Midline glial development is triggered by EGF-receptor signalling, whereas lateral glial development is controlled by the gcm gene. Subsequent glial cell differentiation depends partly on the pointed gene. Here we describe a novel component required for all CNS glia development. The tramtrack gene encodes two zinc-finger proteins, one of which, ttkp69, is expressed in all non-neuronal CNS cells. We show that ttkp69 is downstream of gcm and can repress neuronal differentiation. Double mutant analysis and coexpression experiments indicate that glial cell differentiation may depend on a dual process, requiring the activation of glial differentiation by pointed and the concomitant repression of neuronal development by tramtrack. 相似文献
137.
The effect of high oxide field stress is studied using capacitance-time (C-t) measurements of MOS capacitors. The stress results in parallel shifts of the C-t curve along the time axis. The flatband voltage shift ΔVFB obtained from the initial deep depletion capacitance C(t=0+) follows the same trend as that from the high-frequency C-V characteristics. However, the discrepancy between the two flatband voltages becomes larger as the stress increases due to the effect of interface charges on C-t characteristics. The flatband voltage difference is converted to interface trap density, showing a steady increase of interface trap density with stress, similar to that from low-frequency C-V measurements 相似文献
138.
This paper presents the design criteria, procedure, and implementation of a soft-switched power-factor-correction (PFC) circuit based on the extended-period quasi-resonant (EPQR) principles. All power electronic devices including switches and diodes in the circuit are fully soft switched. The design method is demonstrated in a prototype circuit. The operating principles are confirmed with computer simulation and experimental results. A comparison of the EP-QR operation and zero-voltage-transition (ZVT) pulse-width modulation (PWM) method 相似文献
139.
Sugawara F. Aoki K. Yamaguchi H. Sasaki K. Sasaki T. Fujisaki H. 《Electron Device Letters, IEEE》1997,18(10):483-485
A new lateral MOS-gated thyristor, called the Base-Current-Controlled Thyristor, is described. This device is designed so that most holes at the on-stage reach the P base through the floating P+ region adjacent to the P base and the on-state MOSFET. At the turn-off stage, the interruption of the hole current to the P base due to switching off the above MOSFET occurs simultaneously with the conventional turn-off operation. The concept of this device is verified experimentally by using the fabricated lateral device with the external MOSFET. This device exhibits a better trade-off relation between the on-state voltage and the turn-off time compared uith the conventional MOS-gated thyristor 相似文献
140.
Single-phase voltage source power converters (VSCs) under consideration are AC-DC current-controlled boost-type power converters with bidirectional power-handling capability. Equivalence between two series-connected two-level power converters and a single three-level power converter is considered here. Further considered is the series operation of three-level power converters. Simulation results and experimental verification for both are provided. Economical configurations of three-level power converters leading to multilevel waveforms are presented thereafter 相似文献