Using the "tagged" rRNA gene system, which allows in vivo mutational analysis of Saccharomyces cerevisiae rRNA, we studied the role of two distinct structural elements of 26S rRNA in ribosome biogenesis and function--namely, the evolutionarily highly conserved "GTPase center" located in domain II and the eukaroyote-specific variable region V9 in domain III. Replacement of the S. cerevisiae GTPase center with its counterpart from Escherichia coli did not affect the assembly of the mutant 26S rRNA into functional (as judged by their polysomal distribution) 60S subunits, indicating that the E. coli GTPase center functions efficiently in the context of the heterologous rRNA. Removal of most of the S. cerevisiae V9 region or replacement of this segment by the equivalent segment from mouse 28S rRNA also did not affect the formation of functional 60S subunits carrying the mutant 26S rRNA. Therefore, the V9 region does not seem to play a role in the biological functioning of the yeast 60S subunits, and these subunits appear to be able to accommodate V9 regions of various size and secondary structure without apparent loss of function. 相似文献
Objectives: Relatively few studies have explored the possibility of acute cognitive effects of multivitamin ingestion. This report explores the acute brain electrophysiological changes associated with multivitamin and mineral supplementation, with and without guaraná, using the steady-state visually evoked potential (SSVEP).
Methods: Based on the known SSVEP correlates of A-X continuous performance task (CPT) performance, and sensitivity to acute psychopharmacological manipulations, the A-X CPT was adopted as a task paradigm to explore treatment-related neurophysiological changes in attentional processing. Twenty healthy non-smoking adults aged 21–39 years (mean age = 28.35 years, SD = 5.52) took part in this double-blind, placebo-controlled, randomized, balanced crossover design study.
Results: The study demonstrated both transient and tonic changes in the SSVEP response during completion of the A-X CPT following multivitamin and mineral treatment both with and without guaraná. Transient changes in SSVEP response in prefrontal regions were observed after a single dose of a multivitamin and mineral preparation indicative of enhanced activity within brain regions engaged by the attentional demands of the task. This pattern of change in frontal regions was correlated with improved behavioural performance after treatment with the multivitamin and mineral combination. Where tonic shifts in SSVEP response were investigated, multivitamin and mineral treatment was associated with a pattern of increased inhibition across posterior regions, with enhanced excitatory processing in prefrontal regions. In contrast, multivitamin and mineral treatment with additional guaraná showed a tonic shift towards greater excitatory processes after a single treatment, consistent with the caffeine content of this treatment.
Discussion: While preliminary in nature, these findings suggest a single multivitamin/mineral dose is sufficient to impact on functional brain activity in task-related brain regions. 相似文献
The purpose of this study was to evaluate multifocal visual evoked potential (mfVEP) and pattern-reversal visual evoked potential (PVEP) changes in patients with pathology at various levels of the visual pathway determined by other methods. Six patients with different visual pathway disorders, including vascular ischaemic events and compressive optic neuropathy, were reviewed. All patients were tested with both mfVEP and full-field and half-field PVEPs. Results were assessed in relation to other diagnostic tests such as magnetic resonance imaging, Humphrey visual field test, and optical coherence topography. The cases in this study demonstrate a potential higher sensitivity of mfVEP compared with conventional PVEPs in detecting lesions affecting the peripheral field, horizontal hemifields, and lesions of the post-chiasmal pathway. The limitation of the PVEP in this setting is probably due to phase cancellation and overrepresentation of the macular region. mfVEP provides a more accurate assessment of visual defects when compared with conventional PVEP. The independent assessment of different areas of the visual field improves the detection and localization of lesions and provides an objective topographical map that can be used in clinical practice as an adjunct to other diagnostic tests and to assess disease progression. 相似文献
OBJECTIVE: To estimate and compare the current and future direct cost of overactive bladder (OAB) to the health care systems of five European countries. METHOD: A health economic model was created to estimate the number of people currently affected by OAB symptoms, the expected number to be affected in the future, and the resultant economic burden on health care systems in Germany, Italy, Spain, Sweden, and the United Kingdom. RESULTS: The model estimated that in 2000, 20.2 million people over age 40 in the five countries experienced the symptoms of OAB; 7 million of these had urgency with urge incontinence. This figure is expected to rise to 25.5 million by 2020, including 9 million who will have urgency with urge incontinence. Average annual direct costs of OAB management ranged from euro269 to euro706 per patient per year. The largest cost was the use of incontinence pads, accounting for an average of 63% of the annual per patient cost of OAB management. Total cost to health care systems across all five countries was estimated at euro4.2 billion in 2000, and by 2020, the expected total cost was estimated to be euro5.2 billion, an increase of euro1 billion (26%). CONCLUSION: OAB is prevalent, with a substantial direct cost that is anticipated to increase in the future in line with aging populations. The overall burden, including indirect costs, may be considerably larger, and will fall predominantly on the elderly OAB population with urge incontinence. Recommended medical treatments could help manage those costs and should be evaluated. 相似文献
We report the rare occurrence of bilateral low-grade MALT lymphoma of the breast in a 73 year old female. The clinical, pathological and treatment details are discussed, with a review of the literature. 相似文献
To test the hypothesis that latency delay in the fellow eyes of optic neuritis (ON) patients and to compensate for delayed transmission of visual information, latency change of multi-focal visual evoked potential (mfVEP) traces in fellow eyes of 15 ON patients were analyzed. Patients with low risk (LR) for developing multiple sclerosis (MS) were examined separately from MS patients to isolate effect of cortical plasticity from potential pathological changes in disseminated disease. The small increase in latency in fellow eyes of LR group was statistically not significant. In MS patients, the latency was significantly delayed (P<0.02). The magnitude of the latency change in the fellow eyes did not correlate with the severity of latency delay in the affected eyes (R2<0.02, P=0.3). The differences between ON patients with and without MS, reported here, suggest that the presence of disseminated disease plays critical role in latency delay of the fellow eye. 相似文献
A 41-year-old man with prolidase deficiency has had chronic leg ulcers and recurrent cellulitis for most of his life. Until recently he had been hospitalized at least annually for this and suffered significant morbidity as a result. Since commencing topical 5% proline in white soft paraffin ointment to treat the leg ulcers, there has been marked improvement in the ulcers and decreased frequency of hospitalizations for cellulitis. This lends further support to the use of topical proline in the treatment of patients with skin ulcers secondary to prolidase deficiency. 相似文献