New Methodological Approach (new + methodological_approach)

Distribution by Scientific Domains

Selected Abstracts

The pathophysiology of tremor

MUSCLE AND NERVE, Issue 6 2001
Günther Deuschl MD
Abstract Tremor is defined as rhythmic oscillatory activity of body parts. Four physiological basic mechanisms for such oscillatory activity have been described: mechanical oscillations; oscillations based on reflexes; oscillations due to central neuronal pacemakers; and oscillations because of disturbed feedforward or feedback loops. New methodological approaches with animal models, positron emission tomography, and mathematical analysis of electromyographic and electroencephalographic signals have provided new insights into the mechanisms underlying specific forms of tremor. Physiological tremor is due to mechanical and central components. Psychogenic tremor is considered to depend on a clonus mechanism and is thus believed to be mediated by reflex mechanisms. Symptomatic palatal tremor is most likely due to rhythmic activity of the inferior olive, and there is much evidence that essential tremor is also generated within the olivocerebellar circuits. Orthostatic tremor is likely to originate in hitherto unidentified brainstem nuclei. Rest tremor of Parkinson's disease is probably generated in the basal ganglia loop, and dystonic tremor may also originate within the basal ganglia. Cerebellar tremor is at least in part caused by a disturbance of the cerebellar feedforward control of voluntary movements, and Holmes' tremor is due to the combination of the mechanisms producing parkinsonian and cerebellar tremor. Neuropathic tremor is believed to be caused by abnormally functioning reflex pathways and a wide variety of causes underlies toxic and drug-induced tremors. The understanding of the pathophysiology of tremor has made significant progress but many hypotheses are not yet based on sufficient data. Modern neurology needs to develop and test such hypotheses, because this is the only way to develop rational medical and surgical therapies. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 716,735, 2001 [source]

Air Pollution and Daily Emergency Department Visits for Headache in Montreal, Canada

HEADACHE, Issue 3 2008
Mieczyslaw Szyszkowicz PhD
Background., Many studies have indicated that weather can trigger headache. Here we propose a new methodological approach to assess the relationship between weather, ambient air pollution, and emergency department (ED) visits for this condition. Objective., To examine the associations between ED visits for headache and selected meteorological and air pollution factors. Design and Methods., A hierarchical clusters design was used to study 10,497 ED visits for headache (ICD-9: 784) that occurred at a Montreal hospital between 1997 and 2002. The generalized linear mixed models technique was applied to create Poisson models for the clustered counts of visits for headache. Results., Statistically significant positive associations were observed between the number of ED visits for headache and the atmospheric pressure for all and for female visits for 1-day and 2-day lagged exposures. The percentage increase in daily ED female visits was 4.1% (95% CI: 2.0, 6.2), 3.4% (95% CI: 1.4, 5.6), and 2.2% (95% CI: 1.4, 5.6) for current day, 1-day and 2-day lagged exposure to SO2, respectively, for an increase of an interquartile range (IQR) of 2.4 ppb. The percentage increase was also statistically significant for current day and 1-day lagged exposure to NO2 and CO for all and for female visits. Conclusions., Presented findings provide support for the hypothesis that ED visits for headache are correlated to weather conditions and ambient air pollution , to atmospheric pressure and exposure to SO2, NO2, CO, and PM2.5. An increase in levels of these factors is associated with an increase in the number of ED visits for headache. [source]

Exploring social mobility with latent trajectory groups

Patrick Sturgis
Summary., We present a new methodological approach to the study of social mobility. We use a latent class growth analysis framework to identify five qualitatively distinct social class trajectory groups between 1980 and 2000 for male respondents to the 1970 British Cohort Study. We model the antecedents of trajectory group membership via multinomial logistic regression. Non-response, which is a considerable problem in long-term panels and cohort studies, is handled via direct maximum likelihood estimation, which is consistent and efficient when data are missing at random. Our results suggest a combination of meritocratic and ascriptive influences on the probability of membership in the different trajectory groups. [source]

Direct metabolic fingerprinting of commercial herbal tinctures by nuclear magnetic resonance spectroscopy and mass spectrometry,

Matteo Politi
Abstract Introduction Tinctures are widely used liquid pharmaceutical preparations traditionally obtained by maceration of one or more medicinal plants in ethanol,water solutions. Such a process results in the extraction of virtually hundreds of structurally diverse compounds with different polarities. Owing to the large chemical diversity of the constituents present in the herbal tinctures, the analytical tools used for the quality control of tinctures are usually optimised only for the detection of single chemical entities or specific class of compounds. Objective In order to overcome the major limitations of the current methods used for analysis of tinctures, a new methodological approach based on NMR spectroscopy and MS spectrometry has been tested with different commercial tinctures. Methodology Diffusion-edited 1H-NMR (1D DOSY) and 1H-NMR with suppression of the ethanol and water signals have been applied here for the first time to the direct analysis of commercial herbal tinctures derived from Echinacea purpurea, Hypericum perforatum, Ginkgo biloba and Valeriana officinalis. The direct injection of the tinctures in the MS detector in order to obtain the corresponding metabolic profiles was also performed. Results Using both NMR and MS methods it was possible, without evaporation or separation steps, to obtain a metabolic fingerprint able to distinguish between tinctures prepared with different plants. Batch-to-batch homogeneity, as well as degradation after the expiry date of a batch, was also investigated. Conclusion The techniques proposed here represent fast and convenient direct analyses of medicinal herbal tinctures. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Donatello's decapitations and the rhetoric of beheading in Medicean Florence*

Allie Terry
Abstract While Donatello's bronze sculptures of Judith and David are stylistically discrete, and may have been originally created in and for different contexts, they are firmly connected to one another through their content: both figures clearly are characterized as active agents of decapitation. As this article argues, the Medici fostered a familial association with the iconographic, symbolic and practical language of decapitation in Florence since the Albizzi coup of 1433,4, when the family came to be associated with the feast of St John the Baptist's martyrdom, through the placement of the Donatello sculptures in the family palace in the 1460s. Although rarely mentioned in the vast art-historical literature on the Medici, visual allusions to beheadings in paint, performance and sculpture served a rhetorical function in Florence to describe the shifting political status of Cosimo de'Medici and his family. By outlining a cultural map by which this visual rhetoric of decapitation may be charted in relation to the Medici family, this article contributes yet a further layer of meaning to the Donatello sculptures within the larger context of early Medici patronage and politics and offers a new methodological approach for the investigation of early modern Florentine visual culture. [source]

Taxonomic identification of Amazonian tree crowns from aerial photography

Carlos E. González-Orozco
Abstract Question: To what extent can aerial photography be used for taxonomic identification of Amazonian tree crowns? Objective: To investigate whether a combination of dichotomous keys and a web-based interface is a suitable approach to identify tree crowns. Location: The fieldwork was conducted at Tiputini Biodiversity Station located in the Amazon, eastern Ecuador. Methods: High-resolution imagery was taken from an airplane flying at a low altitude (600 m) above the ground. Imagery of the observable upper layer of the tree crowns was used for the analysis. Dichotomous identification keys for different types of crowns were produced and tested. The identification keys were designed to be web-based interactive, using Google Earth as the main online platform. The taxa analysed were Iriartea, Astrocaryum, Inga, Parkia, Cecropia, Pourouma, Guarea, Otoba, Lauraceae and Pouteria. Results: This paper demonstrates that a combination of photo-imagery, dichotomous keys and a web-based interface can be useful for the taxonomic identification of Amazonian trees based on their crown characteristics. The keys tested with an overall identification accuracy of over 50% for five of the ten taxa with three of them showing accuracy greater than 70% (Iriartea, Astrocaryum and Cecropia). Conclusions: The application of dichotomous keys and a web-based interface provides a new methodological approach for taxonomic identification of various Amazonian tree crowns. Overall, the study showed that crowns with a medium-rough texture are less reliably identified than crowns with smoother or well-defined surfaces. [source]

Total estradiol levels in migrant and British-born British Pakistani women: Investigating early life influences on ovarian function

Tessa M. Pollard
The purpose of this study was to test the hypothesis that women who grow up in energetically stressed environments have later menarche and lower total estradiol levels during their reproductive years than do women who grow up in less energetically stressed environments. We assessed total estradiol in a serum sample taken 9,11 days after the start of the menstrual cycle in 26 women who grew up in Pakistan and migrated to the UK as adults, in 28 British-born British Pakistani women, and in 25 British-born women of European origin. Women who grew up in Pakistan reported a later menarche than women who grew up in the UK. However, we found no significant differences between the groups in total estradiol level. Thus our findings do not support the hypothesis that estradiol levels are partially determined during early life. However, having considered our findings in relation to those of other studies, we conclude that new methodological approaches are needed to provide a more definitive test of the hypothesis. Am. J. Hum. Biol. 2009. © 2008 Wiley-Liss, Inc. [source]