Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 3 de 3
Filter
Add more filters










Database
Language
Publication year range
1.
J Neurosci Methods ; 408: 110130, 2024 Aug.
Article in English | MEDLINE | ID: mdl-38653381

ABSTRACT

BACKGROUND: Cortico-cortical evoked potentials (CCEPs) are a common tool for probing effective connectivity in intracranial human electrophysiology. As with all human electrophysiology data, CCEP data are highly susceptible to noise. To address noise, filters and re-referencing are often applied to CCEP data, but different processing strategies are used from study to study. NEW METHOD: We systematically compare how common average re-referencing and filtering CCEP data impacts quantification. RESULTS: We show that common average re-referencing and filters, particularly filters that cut out more frequencies, can significantly impact the quantification of CCEP magnitude and morphology. We identify that high cutoff high pass filters (> 0.5 Hz), low cutoff low pass filters (< 200 Hz), and common average re-referencing impact quantification across subjects. However, we also demonstrate that the presence of noise may impact CCEP quantification, and preprocessing is necessary to mitigate this. We show that filtering is more effective than re-referencing or averaging across trials for reducing most common types of noise. COMPARISON WITH EXISTING METHODS: These results suggest that existing CCEP processing methods must be applied with care to maximize noise reduction and minimize changes to the data. We do not test every available processing strategy; rather we demonstrate that processing can influence the results of CCEP studies. We emphasize the importance of reporting all processing methods, particularly re-referencing methods. CONCLUSIONS: We propose a general framework for choosing an appropriate processing pipeline for CCEP data, taking into consideration the noise levels of a specific dataset. We suggest that minimal gentle filtering is preferable.


Subject(s)
Cerebral Cortex , Evoked Potentials , Signal Processing, Computer-Assisted , Humans , Cerebral Cortex/physiology , Evoked Potentials/physiology , Male , Female , Electroencephalography/methods , Adult , Electrocorticography/methods
2.
J Appl Physiol (1985) ; 122(3): 503-510, 2017 Mar 01.
Article in English | MEDLINE | ID: mdl-28035014

ABSTRACT

Detailed information on the distribution of airway diameters during bronchoconstriction in situ is required to understand the regional response of the lungs. Imaging studies using computed tomography (CT) have previously measured airway diameters and changes in response to bronchoconstricting agents, but the manual measurements used have severely limited the number of airways measured per subject. Hence, the detailed distribution and heterogeneity of airway responses are unknown. We have developed and applied dynamic imaging and advanced image-processing methods to quantify and compare hundreds of airways in vivo. The method, based on CT, was applied to house dust-mite-sensitized and control mice during intravenous methacholine (MCh) infusion. Airway diameters were measured pre- and post-MCh challenge, and the results compared demonstrate the distribution of airway response throughout the lungs during mechanical ventilation. Forced oscillation testing was used to measure the global response in lung mechanics. We found marked heterogeneity in the response, with paradoxical dilation of airways present at all airway sizes. The probability of paradoxical dilation decreased with decreasing baseline airway diameter and was not affected by pre-existing inflammation. The results confirm the importance of considering the lung as an entire interconnected system rather than a collection of independent units. It is hoped that the response distribution measurements can help to elucidate the mechanisms that lead to heterogeneous airway response in vivo.NEW & NOTEWORTHY Information on the distribution of airway diameters during bronchoconstriction in situ is critical for understanding the regional response of the lungs. We have developed an imaging method to quantify and compare the size of hundreds of airways in vivo during bronchoconstriction in mice. The results demonstrate large heterogeneity with both constriction and paradoxical dilation of airways, confirming the importance of considering the lung as an interconnected system rather than a collection of independent units.


Subject(s)
Airway Resistance/drug effects , Bronchi/pathology , Bronchi/physiopathology , Bronchial Provocation Tests , Bronchoconstriction/drug effects , Methacholine Chloride/pharmacology , Animals , Bronchi/drug effects , Bronchoconstrictor Agents/pharmacology , Image Interpretation, Computer-Assisted , Male , Mice , Mice, Inbred C57BL , Pattern Recognition, Automated , Reproducibility of Results , Sensitivity and Specificity , Tomography, X-Ray Computed
3.
FEBS Lett ; 255(1): 149-53, 1989 Sep 11.
Article in English | MEDLINE | ID: mdl-2676596

ABSTRACT

We have obtained sequence data from five proteolytic peptides totalling 102 amino acid residues of the 80 kDa protein kinase C substrate purified from rat brain. The amino acid sequences of these five peptides were compared with that deduced from a cDNA encoding the 87 kDa protein kinase C substrate from bovine brain. The overall amino acid sequence identity within the regions covered by our peptides is 54%. Two peptides aligned at the C- and N-termini of the bovine protein kinase C substrate with a very high degree of homology (more than 80% identity). Two other peptides exhibited 62% and 46% identity with two regions located in the C-terminal half of the bovine protein. The fifth peptide which contains the sequence PEQPEQPEQ did not reveal any similarity with the bovine protein. Based on the homologies of our experimentally determined sequences, which represent about 30% of the deduced sequence of the bovine protein, we suggest that although these protein kinase C substrates are not identical, they may belong to a family of related proteins.


Subject(s)
Brain/enzymology , Protein Kinase C/analysis , Amino Acid Sequence , Amino Acids/analysis , Animals , Base Sequence , Cattle , DNA/analysis , Hydrolysis , Molecular Sequence Data , Peptide Hydrolases , Protein Kinase C/genetics , Rats , Sequence Homology, Nucleic Acid , Substrate Specificity
SELECTION OF CITATIONS
SEARCH DETAIL
...