Severity: Warning
Message: file_get_contents(https://...@pubfacts.com&api_key=b8daa3ad693db53b1410957c26c9a51b4908&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 176
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 176
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 250
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 1034
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3152
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 575
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 489
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
A quantitative mass spectrometry imaging (QMSI) technique using infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) is demonstrated for the antiretroviral (ARV) drug emtricitabine in incubated human cervical tissue. Method development of the QMSI technique leads to a gain in sensitivity and removal of interferences for several ARV drugs. Analyte response was significantly improved by a detailed evaluation of several cationization agents. Increased sensitivity and removal of an isobaric interference was demonstrated with sodium chloride in the electrospray solvent. Voxel-to-voxel variability was improved for the MSI experiments by normalizing analyte abundance to a uniformly applied compound with similar characteristics to the drug of interest. Finally, emtricitabine was quantified in tissue with a calibration curve generated from the stable isotope-labeled analog of emtricitabine followed by cross-validation using liquid chromatography tandem mass spectrometry (LC-MS/MS). The quantitative IR-MALDESI analysis proved to be reproducible with an emtricitabine concentration of 17.2 ± 1.8 μg/gtissue. This amount corresponds to the detection of 7 fmol/voxel in the IR-MALDESI QMSI experiment. Adjacent tissue slices were analyzed using LC-MS/MS which resulted in an emtricitabine concentration of 28.4 ± 2.8 μg/gtissue.
Download full-text PDF |
Source |
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4495968 | PMC |
http://dx.doi.org/10.1007/s00216-014-8220-y | DOI Listing |
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