The aim of the present study was to assess the influence of the calibration mode of a laser fluorescence measurement device on caries detection. While positioning the probe on an occlusal carious lesion or stained fissure using a clamp, the occlusal surface of each of 62 teeth was covered with a light-body silicone impression material to facilitate a reproducible probe position. Then, measurements of the occlusal lesions were performed after standard and individual calibration at four non-carious areas on the buccal surface of each tooth. Mean laser fluorescence values of the occlusal reading point following standard calibration were about 4-5 units higher compared to values measured after individual calibration. After 1 week, readings after both standard and individual calibration were not different from baseline values (p > 0.05). During individual calibration, a mean range of about 2 units could be observed when comparing the readings of the occlusal reading point with respect to the four different areas of each buccal surface. The present study indicates that laser fluorescence readings are dependent on the mode of calibration. Moreover, for individual calibration, the probe position has to be recorded carefully. It is suggested that the same mode of calibration should always be used, when employing laser fluorescence measurements for longitudinal caries monitoring.

Calibration↗

PubMedDate not supplied

[Indications for surgical pulmonary biopsy].

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Biopsy↗

PubMedDate not supplied

Mass spectrometric sequencing of synthetic peptides containing alpha, alpha-dialkylated amino acid residues by MALDI post-source decay analysis.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), a method well-suited for mass determination of biomolecules, has been used to analyze fragment ions generated by post-source decay (PSD) of synthetic peptaibols containing high proportions of the sterically hindered amino acids alpha-amino isobutyric acid (Aib) and isovaline (Iva). Since peptaibols do not have a free N-terminal amino group or side chains subject to protonation, the analyzed peptides saturnisporin SA III, trichotoxin A-50 and chrysospermin B were shown to provide preferred N-terminal and C-terminal a, b, and y fragments as sodium adduct. Additionally, a cleavage of the labile Aib-Probond was observed for all peptides investigated. The fragmentation pattern allowed confirmation of the primary structure and, therefore, demonstrated the usefulness of MALDI-PSD mass spectrometry for sequence analysis of the peptaibols.

Alkylation↗