1P058 Principal component analysis of the pH-dependent conformational transitions of bovine β-lactoglobulin monitored by heteronuclear NMR(Proteins-functions, methodology, and protein enigineering,Oral Presentations)

Changes of the secondary structure of β-lactoglobulin in water–ethanol solutions were studied using infrared spectroscopy. The efficiency of both principal component analysis and two-dimensional correlation spectroscopy in avoiding spectral subtraction of water was evaluated. The kinetic curves assessed from the scores of the first principal component indicated that changes were more pronounced in 50% ethanol solution than in 5% ethanol–water solution. The spectral patterns derived from the eigenvectors made it possible to characterize changes in the secondary structure of the protein. While aggregation was obtained in 50% ethanol solution, α-helices were formed at the detriment of turns in 5% ethanol solution. The two-dimensional correlation spectroscopy provided information on the sequence of events that occurred by adding ethanol to aqueous solutions of β-lactoglobulin. In 5% ethanol solution, the disappearance of turns preceded the formation of α-helices. Moreover, a small amount of aggregates were depicted at the end of the process. Aggregation of the protein was the main event observed in 50% ethanol–water solution. This event was preceded by the disappearance of α-helices. Application of both principal component analysis and two-dimensional correlation spectroscopy to spectra recorded in H2O made it possible to detect small changes not observed on second derivative spectra collected in D2O.

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A German version of the Intermittent Claudication Questionnaire (ICQ): cultural adaptation and validation

VASA ◽

10.1024/0301-1526/a000218 ◽

2012 ◽

Vol 41 (5) ◽

pp. 333-342 ◽

Cited By ~ 3

Author(s):

Kirchberger ◽

Finger ◽

Müller-Bühl

Keyword(s):

Principal Component Analysis ◽

Intermittent Claudication ◽

Completion Time ◽

Short Form ◽

Principal Component ◽

Component Analysis ◽

German Version ◽

Average Completion Time ◽

Sf 36 ◽

Related Quality

Background: The Intermittent Claudication Questionnaire (ICQ) is a short questionnaire for the assessment of health-related quality of life (HRQOL) in patients with intermittent claudication (IC). The objective of this study was to translate the ICQ into German and to investigate the psychometric properties of the German ICQ version in patients with IC. Patients and methods: The original English version was translated using a forward-backward method. The resulting German version was reviewed by the author of the original version and an experienced clinician. Finally, it was tested for clarity with 5 German patients with IC. A sample of 81 patients were administered the German ICQ. The sample consisted of 58.0 % male patients with a median age of 71 years and a median IC duration of 36 months. Test of feasibility included completeness of questionnaires, completion time, and ratings of clarity, length and relevance. Reliability was assessed through a retest in 13 patients at 14 days, and analysis of Cronbachs alpha for internal consistency. Construct validity was investigated using principal component analysis. Concurrent validity was assessed by correlating the ICQ scores with the Short Form 36 Health Survey (SF-36) as well as clinical measures. Results: The ICQ was completely filled in by 73 subjects (90.1 %) with an average completion time of 6.3 minutes. Cronbachs alpha coefficient reached 0.75. Intra-class correlation for test-retest reliability was r = 0.88. Principal component analysis resulted in a 3 factor solution. The first factor explained 51.5 of the total variation and all items had loadings of at least 0.65 on it. The ICQ was significantly associated with the SF-36 and treadmill-walking distances whereas no association was found for resting ABPI. Conclusions: The German version of the ICQ demonstrated good feasibility, satisfactory reliability and good validity. Responsiveness should be investigated in further validation studies.

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