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排序方式: 共有525条查询结果,搜索用时 15 毫秒
71.
AJ Van Oosterhout B Van Esch G Hofman CL Hofstra I Van Ark FP Nijkamp ML Kapsenberg HF Savelkoul FR Weller 《Canadian Metallurgical Quarterly》1998,19(4):622-628
Microelectrode recording methods for stereotactic localization of the subthalamic nucleus (STN) and surrounding structures are described. These methods accurately define targets for chronic deep brain stimulation in the treatment of Parkinson's disease. Mean firing rates and a burst index were determined for all recorded neurons, and responses to active and passive limb and orofacial movements were tested. STN neurons had a mean firing rate of 37+/-17 Hz (n = 248) and an irregular firing pattern (median burst index, 3.3). Movement-related activity and tremor cells were identified in the STN. Ventral to the STN, substantia nigra pars reticulata neurons had a mean rate of 71+/-23 Hz (n = 56) and a more regular firing pattern (median burst index, 1.7). Short trains (1-2 seconds) of electrical microstimulation of STN could produce tremor arrest but were not found to be useful for localization. Compared with data from normal monkeys our findings suggest that STN neuronal activity is elevated in Parkinson's disease. 相似文献
72.
A neodymium-doped fibre laser has been actively mode-locked to produce pulses shorter than 120 ps using an intracavity acousto-optic loss modulator. The laser operated at 1.088 μm at an average power of 5 mW when pumped by an injection-locked diode array, which coupled approximately 40 mW of 0.82 μm into the fibre. A peak pulse power of 1 kW was obtained in Q -switched operation 相似文献
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Denney Douglas R.; Stephenson Laura A.; Penick Elizabeth C.; Weller Ronald A. 《Canadian Metallurgical Quarterly》1988,97(4):499
This study enumerated lymphocyte subclasses in the peripheral circulation of 15 patients with current diagnoses of major depressive disorder using monoclonal antibodies and flow cytometry. Depressed patients were found to have smaller numbers of helper (T4+), suppressor (T8+), and total T cells (T11+) relative to individually matched, normal controls, but no differences occurred between groups in the ratio of helper to suppressor cells. Furthermore, the helper, suppressor, and total T cell counts were found to be inversely related to patients' self-reported depression scores. The peripheral circulation of patients with major depression seems to be characterized by proportionately equal reductions in the numbers of helper and suppressor T cells, with the magnitude of these reductions being related to the severity of clinical depression among such patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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The desirability of remotely switching electronic circuits implanted within the body is explained, and the properties of a suitable switch are listed. The circuit details of a solid-state device developed for an implantable transmitter and consisting essentially of a complementary pair of transistors are given. 相似文献
77.
Of 402 patients with cancers of the oral cavity, oropharynx, and supraglottic larynx treated at Stanford between 1957 and 1972, 164 had clinically uninvolved cervical lymph nodes prior to the initiation of radiation therapy. Lymph node metastases developed later in 38 per cent of patients with primary oral cavity carcinomas who were treated with interstitial radium implants alone. No late cervical lymph node involvement was found in those patients who received high dose external irradiation to at least the primary site and first echelon lymph nodes. Lymph node failures were ultimately noted in 20 of the 140 patients (14 per cent), who received partial or complete neck irradiation, but 18 of these occurred in patients with uncontrolled primary lesions, suggesting that re-seeding of cervical lymph nodes had taken place rather than failure of the initial irradiation to control subclinical metastases. Our present policy is to treat the primary lesion and adjacent lymph nodes with high dose megavoltage techniques, combined with interstitial irradiation if possible. Bilateral supplemental inferior neck radiation ports are added for patients with advanced primary neoplasms and for those with clinically involved cervical lymph nodes. All other patients undergoing radiation therapy for stage T1 primary lesions and clinically negative necks also receive ipsilateral low neck irradiation. In addition, cervical lymph nodes are electively irradiated when the primary lesion has been resected. When these policies are adopted, the incidence of cervical lymph node failures is extremely low in patients whose primary sites remain controlled, and morbidity from the cervical radiation fields is negligible. 相似文献
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Anna T. Backes Kathrin Reinmuth-Selzle Anna Lena Leifke Kira Ziegler Carola S. Krevert Georg Tscheuschner Kurt Lucas Michael G. Weller Thomas Berkemeier Ulrich Pschl Janine Frhlich-Nowoisky 《International journal of molecular sciences》2021,22(14)
The allergenic and inflammatory potential of proteins can be enhanced by chemical modification upon exposure to atmospheric or physiological oxidants. The molecular mechanisms and kinetics of such modifications, however, have not yet been fully resolved. We investigated the oligomerization and nitration of the grass pollen allergen Phl p 5 by ozone (O3), nitrogen dioxide (NO2), and peroxynitrite (ONOO–). Within several hours of exposure to atmospherically relevant concentration levels of O3 and NO2, up to 50% of Phl p 5 were converted into protein oligomers, likely by formation of dityrosine cross-links. Assuming that tyrosine residues are the preferential site of nitration, up to 10% of the 12 tyrosine residues per protein monomer were nitrated. For the reaction with peroxynitrite, the largest oligomer mass fractions (up to 50%) were found for equimolar concentrations of peroxynitrite over tyrosine residues. With excess peroxynitrite, the nitration degrees increased up to 40% whereas the oligomer mass fractions decreased to 20%. Our results suggest that protein oligomerization and nitration are competing processes, which is consistent with a two-step mechanism involving a reactive oxygen intermediate (ROI), as observed for other proteins. The modified proteins can promote pro-inflammatory cellular signaling that may contribute to chronic inflammation and allergies in response to air pollution. 相似文献