888 research outputs found
Contrasting phenotypes of putative proprioceptive and nociceptive trigeminal neurons innervating jaw muscle in rat
BACKGROUND: Despite the clinical significance of muscle pain, and the extensive investigation of the properties of muscle afferent fibers, there has been little study of the ion channels on sensory neurons that innervate muscle. In this study, we have fluorescently tagged sensory neurons that innervate the masseter muscle, which is unique because cell bodies for its muscle spindles are in a brainstem nucleus (mesencephalic nucleus of the 5(th )cranial nerve, MeV) while all its other sensory afferents are in the trigeminal ganglion (TG). We examine the hypothesis that certain molecules proposed to be used selectively by nociceptors fail to express on muscle spindles afferents but appear on other afferents from the same muscle. RESULTS: MeV muscle afferents perfectly fit expectations of cells with a non-nociceptive sensory modality: Opiates failed to inhibit calcium channel currents (I(Ca)) in 90% of MeV neurons, although I(Ca )were inhibited by GABA(B )receptor activation. All MeV afferents had brief (1 msec) action potentials driven solely by tetrodotoxin (TTX)-sensitive Na channels and no MeV afferent expressed either of three ion channels (TRPV1, P2X3, and ASIC3) thought to be transducers for nociceptive stimuli, although they did express other ATP and acid-sensing channels. Trigeminal masseter afferents were much more diverse. Virtually all of them expressed at least one, and often several, of the three putative nociceptive transducer channels, but the mix varied from cell to cell. Calcium currents in 80% of the neurons were measurably inhibited by μ-opioids, but the extent of inhibition varied greatly. Almost all TG masseter afferents expressed some TTX-insensitive sodium currents, but the amount compared to TTX sensitive sodium current varied, as did the duration of action potentials. CONCLUSION: Most masseter muscle afferents that are not muscle spindle afferents express molecules that are considered characteristic of nociceptors, but these putative muscle nociceptors are molecularly diverse. This heterogeneity may reflect the mixture of metabosensitive afferents which can also signal noxious stimuli and purely nociceptive afferents characteristic of muscle
Recommended from our members
Assessment of inter-examiner agreement and variability in the manual classification of auditory brainstem response
Abstract
Background: The analysis of the Auditory Brainstem Response (ABR) is of
fundamental importance to the investigation of the auditory system behaviour,
though its interpretation has a subjective nature because of the manual process
employed in its study and the clinical experience required for its analysis. When
analysing the ABR, clinicians are often interested in the identification of ABR signal
components referred to as Jewett waves. In particular, the detection and study of
the time when these waves occur (i.e., the wave latency) is a practical tool for the
diagnosis of disorders affecting the auditory system. Significant differences in
inter-examiner results may lead to completely distinct clinical interpretations of the
state of the auditory system. In this context, the aim of this research was to evaluate
the inter-examiner agreement and variability in the manual classification of ABR.
Methods: A total of 160 ABR data samples were collected, for four different stimulus
intensity (80dBHL, 60dBHL, 40dBHL and 20dBHL), from 10 normal-hearing subjects
(5 men and 5 women, from 20 to 52 years). Four examiners with expertise in the
manual classification of ABR components participated in the study. The Bland-Altman
statistical method was employed for the assessment of inter-examiner agreement
and variability. The mean, standard deviation and error for the bias, which is the
difference between examiners’ annotations, were estimated for each pair of
examiners. Scatter plots and histograms were employed for data visualization and
analysis.
Results: In most comparisons the differences between examiner’s annotations were
below 0.1 ms, which is clinically acceptable. In four cases, it was found a large error
and standard deviation (>0.1 ms) that indicate the presence of outliers and thus,
discrepancies between examiners.
Conclusions: Our results quantify the inter-examiner agreement and variability of
the manual analysis of ABR data, and they also allows for the determination of
different patterns of manual ABR analysis
The beta Pictoris association: Catalog of photometric rotational periods of low-mass members and candidate members
We intended to compile the most complete catalog of bona fide members and
candidate members of the beta Pictoris association, and to measure their
rotation periods and basic properties from our own observations, public
archives, and exploring the literature. We carried out a multi-observatories
campaign to get our own photometric time series and collected all archived
public photometric data time series for the stars in our catalog. Each time
series was analyzed with the Lomb-Scargle and CLEAN periodograms to search for
the stellar rotation periods. We complemented the measured rotational
properties with detailed information on multiplicity, membership, and projected
rotational velocity available in the literature and discussed star by star. We
measured the rotation periods of 112 out of 117 among bona fide members and
candidate members of the beta Pictoris association and, whenever possible, we
also measured the luminosity, radius, and inclination of the stellar rotation
axis. This represents to date the largest catalog of rotation periods of any
young loose stellar association. We provided an extensive catalog of rotation
periods together with other relevant basic properties useful to explore a
number of open issues, such as the causes of spread of rotation periods among
coeval stars, evolution of angular momentum, and lithium-rotation connection.Comment: Forthcoming article, Received: 20 June 2016 / Accepted: 09 September
2016; 40 pages, 2 figures. The online figures A1-A73 are available at CD
Rendimento industrial e composição quÃmica de milho de alta qualidade protéica em relação a hÃbridos comerciais.
A dureza do endosperma do milho é atributo essencial para produtores e indústrias que utilizam este cereal como matéria-prima. Porém, os milhos de alta qualidade protéica (Quality Protein Maize – QPM) apresentam alterações na textura do grão, dificultando seu uso comercial. Este trabalho avaliou o rendimento industrial na degerminação do grão e fracionamento do endosperma, e a composição quÃmica de uma variedade de milho QPM, em relação a hÃbridos comerciais de milho comum
Radio and optical intra-day variability observations of five blazars
We carried out a pilot campaign of radio and optical band intra-day
variability (IDV) observations of five blazars (3C66A, S5 0716+714, OJ287,
B0925+504, and BL Lacertae) on December 18--21, 2015 by using the radio
telescope in Effelsberg (Germany) and several optical telescopes in Asia,
Europe, and America. After calibration, the light curves from both 5 GHz radio
band and the optical R band were obtained, although the data were not smoothly
sampled over the sampling period of about four days. We tentatively analyse the
amplitudes and time scales of the variabilities, and any possible periodicity.
The blazars vary significantly in the radio (except 3C66A and BL Lacertae with
only marginal variations) and optical bands on intra- and inter-day time
scales, and the source B0925+504 exhibits a strong quasi-periodic radio
variability. No significant correlation between the radio- and optical-band
variability appears in the five sources, which we attribute to the radio IDV
being dominated by interstellar scintillation whereas the optical variability
comes from the source itself. However, the radio- and optical-band variations
appear to be weakly correlated in some sources and should be investigated based
on well-sampled data from future observations.Comment: 6 pages, 6 figures, accepted by MNRA
- …