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Of Studies (of + studies)

Distribution by Scientific Domains
Medical Sciences50%
Life Sciences37%

Kinds of Of Studies

  • variety of studies
    		•

    Selected Abstracts

    Recovery of flagellar dynein function in a Chlamydomonas actin/dynein-deficient mutant upon introduction of muscle actin by electroporation

    CYTOSKELETON, Issue 3 2001
    Masahito Hayashi
    Abstract Flagellar and ciliary inner-arm dyneins contain actin as a subunit; however, the function of this actin subunit remains unknown. As a first step toward experimental manipulation of actin in dynein, we developed a method for introducing exogenous actin into Chlamydomonas cells by electroporation. A non-motile mutant, ida5oda1, lacking inner-arm dyneins due to the absence of conventional actin, was electroporated in the presence of rabbit skeletal muscle actin. About 20% of the electroporated cells recovered motility under optimal conditions. In addition, by taking advantage of their phototactic behavior, the rescued cells could be concentrated. Motility was also recovered with fluorescently labeled actin; in this case, axonemes became fluorescent after electroporation, suggesting that actin was in fact incorporated as a dynein subunit. The feasibility of incorporating a substantial amount of macromolecules by electroporation will be useful not only for studying actin function, but also for a variety of studies using Chlamydomonas in which no efficient methods have been developed for expressing or introducing foreign proteins and other macromolecules. Cell Motil. Cytoskeleton 49:146,153, 2001. © 2001 Wiley-Liss, Inc. [source]

    The gluten connection: the association between schizophrenia and celiac disease

    ACTA PSYCHIATRICA SCANDINAVICA, Issue 2 2006
    A. E. Kalaydjian
    Objective:, Schizophrenia affects roughly 1% of the population and is considered one of the top 10 causes of disability worldwide. Given the immense cost to society, successful treatment options are imperative. Based on initial findings, gluten withdrawal may serve as a safe and economical alternative for the reduction of symptoms in a subset of patients. Method:, A review of the literature relevant to the association between schizophrenia and celiac disease (gluten intolerance) was conducted. Results:, A drastic reduction, if not full remission, of schizophrenic symptoms after initiation of gluten withdrawal has been noted in a variety of studies. However, this occurs only in a subset of schizophrenic patients. Conclusion:, Large-scale epidemiological studies and clinical trials are needed to confirm the association between gluten and schizophrenia, and address the underlying mechanisms by which this association occurs. [source]

    Influence of narrowband UVB phototherapy on vitamin D and folate status

    EXPERIMENTAL DERMATOLOGY, Issue 8 2010
    Emanuela Cicarma
    Please cite this paper as: Influence of narrowband UVB phototherapy on vitamin D and folate status. Experimental Dermatology 2010; 19: e67,e72. Abstract Background:, A variety of studies have shown beneficial effects of different types of phototherapy in skin disorders. Such therapy leads to enhanced cutaneous vitamin D synthesis, which may be one of the mechanisms of action. Furthermore, another nutrient, folate, can probably also be influenced by UV radiation. Objective:, The aim of our study was to investigate the influence of low-dose narrowband UVB (nUVB) phototherapy of patients with psoriasis, atopic eczema and other skin disorders on serum levels of 25(OH) vitamin D (the serum marker for vitamin D status) and on serum and erythrocyte-folate. Methods:, 25(OH) vitamin D (25(OH)D), serum and erythrocyte-folate levels were measured before and after low-dose nUVB (TL-01 tubes) phototherapy of these patients. The spectrum of the TL-01 tube was compared with the solar spectrum, and the efficiency spectra of vitamin D photosynthesis were calculated. Results:, For patients with a high initial 25(OH)D serum level (> 80 nmol/l), no significant (P = 0.36) increase in 25(OH)D levels was seen, in contrast to patients with a low initial level (< 80 nmol/l) where a significant increase (P < 0.001) was observed. The increase was 30,60%, depending on the UVB dose (2.35,13.4 J/cm2). No significant nUVB-effect was found on the erythrocyte and serum-folate level. Conclusion:, Low-dose nUVB treatment gives a significant increase (P < 0.001) of the vitamin D status in persons with low initial levels of 25(OH)D, but no effect on the folate level. [source]

    A single-trace dual-process model of episodic memory: A novel computational account of familiarity and recollection

    HIPPOCAMPUS, Issue 2 2010
    Andrea Greve
    Abstract Dual-process theories of episodic memory state that retrieval is contingent on two independent processes: familiarity (providing a sense of oldness) and recollection (recovering events and their context). A variety of studies have reported distinct neural signatures for familiarity and recollection, supporting dual-process theory. One outstanding question is whether these signatures reflect the activation of distinct memory traces or the operation of different retrieval mechanisms on a single memory trace. We present a computational model that uses a single neuronal network to store memory traces, but two distinct and independent retrieval processes access the memory. The model is capable of performing familiarity and recollection-based discrimination between old and new patterns, demonstrating that dual-process models need not to rely on multiple independent memory traces, but can use a single trace. Importantly, our putative familiarity and recollection processes exhibit distinct characteristics analogous to those found in empirical data; they diverge in capacity and sensitivity to sparse and correlated patterns, exhibit distinct ROC curves, and account for performance on both item and associative recognition tests. The demonstration that a single-trace, dual-process model can account for a range of empirical findings highlights the importance of distinguishing between neuronal processes and the neuronal representations on which they operate. © 2009 Wiley-Liss, Inc. [source]

    Averaged Periodogram Spectral Estimation with Long-memory Conditional Heteroscedasticity

    JOURNAL OF TIME SERIES ANALYSIS, Issue 4 2001
    Marc Henry
    The empirical relevance of long-memory conditional heteroscedasticity has emerged in a variety of studies of long time series of high frequency financial measurements. A reassessment of the applicability of existing semiparametric frequency domain tools for the analysis of time dependence and long-run behaviour of time series is therefore warranted. To that end, in this paper the averaged periodogram statistic is analysed in the framework of a generalized linear process with long-memory conditional heteroscedastic innovations according to a model specification first proposed by Robinson (Testing for strong serial correlation and dynamic conditional heteroscedasticity in multiple regression. J. Economet. 47 (1991), 67,84). It is shown that the averaged periodogram estimate of the spectral density of a short-memory process remains asymptotically normal with unchanged asymptotic variance under mild moment conditions, and that for strongly dependent processes Robinson's averaged periodogram estimate of long memory (Semiparametric analysis of long memory time series. Ann. Stat. 22 (1994), 515,39) remains consistent. [source]

    A Survey of Polymerase Chain Reaction (PCR) Amplification Studies of Unicellular Protists Using Single-Cell PCR

    THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 5 2009
    DENIS H. LYNN
    ABSTRACT. We surveyed a variety of studies that have used single-cell polymerase chain reaction (SC-PCR) to examine the gene sequences of a diversity of unicellular protists. Representatives of all the Super-Groups of eukaryotes have been subjected to SC-PCR with ciliates and dinoflagellates being most commonly examined. The SC-PCR was carried out either by directly amplifying a single lysed cell or by first extracting DNA and following this with amplification of the DNA extract. Cell lysis methods included heating, freezing, mechanical rupture, and enzyme digestion. Cells fixed or preserved with ethanol, methanol, and Lugol's have also been used successfully. Heminested or seminested PCR might follow the initial PCR, whose products were then directly sequenced or cloned and then sequenced. The methods are not complicated. This should encourage protistologists to use SC-PCR in the description of new or revised taxa, especially rare and unculturable forms, and it should also enable the probing of gene expression in relation to life history stages. [source]

    The Canalith Repositioning Procedure for Benign Positional Vertigo: A Meta-Analysis,

    THE LARYNGOSCOPE, Issue 7 2004
    Bradford Alan Woodworth MD
    Abstract Objective: To review the effectiveness of the canalith repositioning procedure (CRP) in the treatment of benign paroxysmal positional vertigo (BPPV) with a critical review of the literature and meta-analysis. Study Design: Meta-analysis. Methods: Studies eligible for inclusion were randomized, controlled trials of the CRP performed on clearly defined cases of BPPV. A total of nine studies meeting inclusion criteria were identified by two independent literature searches of Medline. Treatment and control groups were compared for symptom resolution and elimination of a positive Dix-Hallpike test. Results: Patients treated with CRP were more likely to demonstrate symptom resolution (odds ratio [OR] 4.6; 95% confidence interval [CI] 2.8,7.6) and negative Dix-Hallpike (OR 5.2; 95% CI 3.0,8.8) at the time of first follow-up. The effect of CRP for symptom improvement was strongest within the first month after treatment (OR 4.1; 95% CI 3.1,5.2) with some decline thereafter (OR 2.8; 95% CI 1.7,3.9). Conversely, the ability of CRP to produce a negative Dix-Hallpike strengthened between the first month after treatment (OR 3.0; 95% CI 1.8,4.0) and later follow-up times (OR 5.0; 95% CI 3.9,6.1). Conclusions: The CRP is more effective than control in resolving vertigo and positive Dix-Hallpike associated with BPPV. This finding was consistent among a variety of studies using different study designs. Untreated patients may demonstrate symptom improvement with time; however, many will continue to have a positive Dix-Hallpike when examined. Resolution of vertigo in untreated patients is therefore most likely because of avoidance of provocative positions. [source]

    Role of NO in retinal vascular disease

    ACTA OPHTHALMOLOGICA, Issue 2009
    L SCHMETTERER
    Purpose Nitric oxide (NO) is a key regulator of vascular tone in all vascular beds including the eye. Hence, inhibition of NO synthase with L-arginine analogues leads to a reduction of blood flow to all ocular tissues. This enables the investigation of the role of NO in the physiology of blood flow regulation, but also abnormalities of the vascular L-arginine/NO system in ocular vascular disease. Methods A variety of studies investigating the role of NO in healthy humans but also in patients with vascular disease is summarized. Results Inhibition of NO synthase reduces retinal, choroidal and optic nerve head blood. A variety of studies also indicate that NO plays a role in the ocular vasodilator effects of numerous agonists including acetylcholine, bradykinin, carbon dioxide, histamine and insulin. In addition, NO appears to modulate the autoregulatory behavior of ocular vascular beds and is involved in retinal neurovascular coupling. In several ocular diseases such as diabetic retinopathy or open angle glaucoma abnormalities in the NO system can be observed. Conclusion NO is a major regulator of ocular blood flow in humans. The existence of different NO synthase isoforms makes it, however, difficult to therapeutically intervent via the L-arginine/NO pathway. Further studies are required to characterize the role of the NO synthase isoforms in the control of ocular blood flow in more detail and to allow for therapeutic interventions in ischemic ocular eye disease via this attractive pathway. [source]