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991.
CJ Jeng SA McCarroll TF Martin E Floor J Adams D Krantz S Butz R Edwards ES Schweitzer 《Canadian Metallurgical Quarterly》1998,140(3):685-698
To understand the influence of the ascending path linking area 17 to area 18 of visual cortices, experiments were carried out in which a small neuronal population of area 17 was inactivated with GABA, while unitary responses were recorded in area 18. In the latter, cells are identified as belonging to the simple or complex family according to their firing pattern evoked in response to sine-wave gratings scrolling through the receptive fields. Anesthetized cats were prepared for single-cell recordings. In area 17, a GABA-containing pipette was placed in superficial layers in order to inactivate reversibly a small neuronal population. Prior to blockade, the orientation tuning curves were obtained in both areas and the difference in optimal orientation between areas 17 and 18 was recorded. In area 18, cells were classified as simple or complex. The strategy was to study the reaction of neurons in area 18 prior to, during and after area 17 depression. In most simple cells, whenever the difference in orientation was in the iso-range, that is when the difference in optimal orientations of the injected site (in area 17) and of the neuron in area 18 was less than 30 degrees, the GABA application produced a decline of the evoked discharges, whereas GABA injection augmented the evoked firing rate when the difference was in the cross-range (>60 degrees). In contrast to simple cells, GABA depression enhanced the responses in the majority of complex cells with like orientations in both areas. When the difference between recording sites was in the cross-range, then area 17 depression produced weaker evoked firing. A tangential penetration of the injecting pipette, allowing injection of different orientation sites while testing the same unit in area 18, revealed that the latter could react with an enhancement or a decline of the responses as the injecting pipette shifted from iso (or cross) to cross (or iso) disparity in optimal orientations between areas 17 and 18. These results suggest that the path connecting area 17 to area 18 may be functionally discriminated on the basis of the orientation domain and cell types. In addition, our data suggest that the ascending visual streams are required to generate orientation specificity in area 18. 相似文献
992.
AM van den Besselaar CJ van Rijn DA Taberner LJ Goodman L Poller K Clarke 《Canadian Metallurgical Quarterly》1997,78(2):852-854
Adequate heat stability of international reference preparations (IRP) for thromboplastin (tissue factor) is an essential requirement. Accelerated degradation testing was performed by three laboratories on two candidate IRP for recombinant human tissue factor. Heat treatment of these candidates resulted in slight shortening of the PT, contrasting with heat-induced prolongation of the PT observed with a conventional human brain derived IRP. Heat stability of these candidates was improved when compared with the stability of previous recombinant human tissue factor preparations. The PT-ratio did not change significantly when the candidates were stored for 28 days at 44 degrees C. It can therefore be concluded that both candidates are acceptable with regard to stability. 相似文献
993.
BW Corn RM Lanciano R D''agostino E Kiggundu CJ Dunton P Purser KM Greven 《Canadian Metallurgical Quarterly》1997,66(3):411-416
Water-soluble amyloid beta-peptides (sA beta), ending at residue 42, precede amyloid plaques in Down's syndrome (DS). Here we report that sA beta consists of the full-length A beta(1-42) and peptides truncated and modified by cyclization of the N-terminal glutamates, A beta[3(pE)-42] and A beta[11(pE)-42]. The A beta[3(pE)-42] peptide is the most abundant form of sA beta in Alzheimer's disease (AD) brains. In DS, sA beta[3(pE)-42] concentration increases with age and the peptide becomes a dominant species in the presence of plaques. Both pyroglutamate-modified peptides and the full-length A beta form a stable aggregate that is water soluble. The findings point to a crucial role of the aggregated and modified sA beta in the plaque formation and pathogenesis of AD. 相似文献
994.
995.
Mutations in the facC gene of Aspergillus nidulans result in an inability to use acetate as a sole carbon source. This gene has been cloned by complementation. The proposed translation product of the facC gene has significant similarity to carnitine acetyltransferases (CAT) from other organisms. Total CAT activity was found to be inducible by acetate and fatty acids and repressed by glucose. Acetate-inducible activity was found to be absent in facC mutants, while fatty acid-inducible activity was absent in an acuJ mutant. Acetate induction of facC expression was dependent on the facB regulatory gene, and an expressed FacB fusion protein was demonstrated to bind to 5' facC sequences. Carbon catabolite repression of facC expression was affected by mutations in the creA gene and a CreA fusion protein bound to 5' facC sequences. Mutations in the acuJ gene led to increased acetate induction of facC expression and also of an amdS-lacZ reporter gene, and it is proposed that this results from accumulation of acetate, as well as increased expression of facB. A model is presented in which facC encodes a cytosolic CAT enzyme, while a different CAT enzyme, which is acuJ dependent, is present in peroxisomes and mitochondria, and these activities are required for the movement of acetyl groups between intracellular compartments. 相似文献
996.
WM Sy IS Seo CJ Homs R Gulrajani P Sze KF Smith J McBride 《Canadian Metallurgical Quarterly》1998,12(2):77-82
OBJECTIVE: The aim of this study was to assess the capability of high-resolution images obtained with a commercially available pelvic phased-array surface coil to demonstrate normal hip anatomy. DESIGN: We retrospectively analyzed the oblique coronal magnetic resonance (MR) images of hips of 36 consecutive patients acquired on a 1.5-T clinical imager using a pelvic phased-array coil as a receiver, a 16-20 cm field of view, and 5 mm slice thickness. PATIENTS: Thirty-six patients were studied, age 15-81 years. There were 20 males and 16 females. RESULTS AND CONCLUSIONS: The articular cartilage, cortex, superior labrum, and iliofemoral ligament were well visualized on proton density weighted fat saturation (PDF) images. The femoral and obturator vessels, obturator nerve, and various muscles were easily seen on T1-weighted images. High-resolution imaging of the hip is achievable in a reasonable amount of time using newer phased-array surface coils and may play an increasing role in the future evaluation of hip disorders. 相似文献
997.
Bayesian methods are commonly used in some analyses of human genetic data, such as segregation and linkage analyses, but they are not typically used for analyses of human twin data. In this paper we develop a scheme for a Bayesian analysis of human twin data. We develop prior elicitation schemes to incorporate historical information. We consider three prior schemes: fully informative, semi-informative and noninformative. We use Markov chain Monte Carlo sampling algorithms to facilitate Bayesian computation and provide detailed implementation schemes. We also develop model diagnostics for assessing the goodness of fit of twin models. Using a simulation study, we show that if the purpose of the study is to estimate the intraclass correlations or heritability in twin studies, then the semi-informative prior is as informative as the fully informative prior. Finally, a real data example is used to illustrate the proposed methodologies. 相似文献
998.
OBJECTIVE: To assess the longer term efficacy of laparoscopic laser surgery in the treatment of painful pelvic endometriosis and to observe the natural history of the disease at second-look laparoscopy in a control group. DESIGN: One-year follow-up of a prospective, randomized, double-blind controlled trial. SETTING: A referral center for the laparoscopic laser treatment of endometriosis. PATIENT(S): Sixty-three patients with pelvic pain and minimal to moderate endometriosis. INTERVENTION(S): After the 6-month follow-up visit, the randomization code was broken, and follow-up was continued to 1 year. Symptomatic patients were offered second-look laser laparoscopy. MAIN OUTCOME MEASURE(S): Continued symptom relief at 1 year after treatment and findings at second-look laparoscopy in symptomatic controls. RESULT(S): Symptom relief continued at 1 year in 90% of those who initially responded. All symptomatic controls had a second-look procedure, with 7 (29%) showing disease progression, 7 (29%) showing disease regression, and 10 (42%) having static disease. CONCLUSION(S): The benefits of laser laparoscopy for painful pelvic endometriosis are continued in the majority of patients at 1 year. Untreated painful endometriosis will progress or remain static in the majority of patients but will spontaneously improve in others. 相似文献
999.
Evaluation of mental retardation: recommendations of a Consensus Conference: American College of Medical Genetics 总被引:1,自引:0,他引:1
CJ Curry RE Stevenson D Aughton J Byrne JC Carey S Cassidy C Cunniff JM Graham MC Jones MM Kaback J Moeschler GB Schaefer S Schwartz J Tarleton J Opitz 《Canadian Metallurgical Quarterly》1997,72(4):468-477
A Consensus Conference utilizing available literature and expert opinion sponsored by the American College of Medical Genetics in October 1995 evaluated the rational approach to the individual with mental retardation. Although no uniform protocol replaces individual clinician judgement, the consensus recommendations were as follows: 1. The individual with mental retardation, the family, and medical care providers benefit from a focused clinical and laboratory evaluation aimed at establishing causation and in providing counseling, prognosis, recurrence risks, and guidelines for management. 2. Essential elements of the evaluation include a three-generation pedigree: pre-, peri-, and post-natal history, complete physical examination focused on the presence of minor anomalies, neurologic examination, and assessment of the behavioral phenotype. 3. Selective laboratory testing should, in most patients, include a banded karyotype. Fragile X testing should be strongly considered in both males and females with unexplained mental retardation, especially in the presence of a positive family history, a consistent physical and behavioral phenotype and absence of major structural abnormalities. Metabolic testing should be initialed in the presence of suggestive clinical and physical findings. Neuroimaging should be considered in patients without a known diagnosis especially in the presence of neurologic symptoms, cranial contour abnormalities, microcephaly, or macrocephaly. In most situations MRI is the testing modality of choice. 4. Sequential evaluation of the patient, occasionally over several years, is often necessary for diagnosis, allowing for delineation of the physical and behavioral phenotype, a logical approach to ancillary testing and appropriate prognostic and reproductive counseling. 相似文献
1000.
CF Hanrahan WG Kimpton CJ Howard KR Parsons MR Brandon AE Andrews AD Nash 《Canadian Metallurgical Quarterly》1997,159(9):4287-4294
Requirements for the activation and proliferation of gammadelta T cells were investigated. Maximum numbers of gammadelta T cells expressed the IL-2R alpha-chain after 6-h Con A stimulation in peripheral blood, efferent lymph, and afferent lymph. In comparison, IL-2R alpha-chain expression on CD4 T cells only reached maximum levels in response to Con A stimulation in peripheral blood and afferent lymph populations. Analysis of enriched gammadelta T cells demonstrated that Con A-induced expression of the IL-2R alpha-chain was independent of APC. Together, these data suggest that the requirements for gammadelta T cell activation are less stringent than those for alphabeta T cell activation. Unfractionated peripheral blood, efferent lymph, and afferent lymph cell populations proliferated in response to Con A alone. In contrast, enriched gammadelta T cells (CD4/CD8 depleted) from efferent lymph did not proliferate in response to Con A alone, but required the addition of IL-2. This requirement for exogenous IL-2 could be overcome by the addition of dendritic cells purified from afferent lymph. These results suggested that gammadelta T cells required costimulatory signals provided by APC to ensure the production of sufficient IL-2 to drive proliferation. CD28 and CTLA-4 mRNA were detected in efferent lymph and afferent lymph populations containing CD4 and CD8 T cells stimulated with Con A and IL-2 or with Con A alone, respectively. In contrast, negligible levels of these mRNA species were detected in efferent and afferent lymph populations devoid of CD4 and CD8 T cells. These results suggest that ovine gammadelta T cells may use alternative costimulatory pathways. 相似文献