Ultrastructural differences in rectus sheath of hernia patients and healthy controls

On the Nature of Stationary and Time-Resolved Fluorescence Spectroscopy of Collagen Powder from Bovine Achilles Tendon

This paper presents a more systematic study of steady-state and time-resolved autofluorescence spectroscopy of collagen isolated from bovine Achilles tendon. In steady-state fluorescence measurements, the excitation and emission spectra of collagen powder, recorded at different fluorescence excitation and detection wavelengths, were compared with the fluorescence excitation and emission spectra of the amino acids phenylalanine, tyrosine, and tryptophan, as well as with similar spectra for 13 autofluorescent collagen cross-links, which have been identified and described in the literature so far. In time-resolved studies, fluorescence was excited by the pulsed light of different wavelengths, and for each excitation wavelength, fluorescence decay was recorded for several detection wavelengths. Data analysis allowed recovery of the fluorescence decay times for each experimental excitation detection event. The obtained information on the decay times of the measured fluorescent signals was discussed, taking into account the available literature data from similar studies of isolated collagen and collagen-rich tissues. Based on the obtained results, it was found that the shape and position of the measured fluorescence excitation and emission spectra of collagen strongly depend on the emission and excitation wavelengths selected in the measurements. From the recorded excitation and emission bands of collagen, it can be concluded with high probability that there are additional, so far unidentified, collagen cross-links, which can be excited at longer excitation wavelengths. In addition, the collagen excitation spectra were measured at longer emission wavelengths at which the collagen cross-links emit fluorescent light. In addition to the emission spectra obtained for excitation in the deep-UV region, the results of time-resolved fluorescence studies with excitation in the deep-UV region and detection at longer wavelengths suggest that fluorescence excitation energy transfer processes occur from the amino acids to the collagen cross-links, and also between the cross-links themselves.

Probing the use of fluorescence spectroscopy as a novel diagnostic tool in patients with rheumatoid arthritis: applicability in the detection of secondary amyloidosis

Background

Secondary amyloidosis is a frequently reported complication of rheumatoid arthritis. Currently, accepted diagnostic protocols for secondary amyloidosis involve histopathological and histochemical examinations of collected tissue specimens. The purpose of the current report was to evaluate the value of fluorescence spectroscopy as a supplementary tool in the diagnosis of secondary amyloidosis.

Material/Methods

Tissue specimens were collected from abdominal folds, gingiva or rectal mucosa of 99 patients affected with rheumatoid arthritis. Tissue samples were subjected to preliminary clinical observations, histopathological examinations and laboratory tests. These procedures were used to subdivide tissue samples into either amyloid-containing or amyloid-free control subgroups. All collected tissue samples were examined with the use of a designated spectrofluorometer and fluorescence spectral images were generated.

Results

It was found that fluorescence spectra for amyloid-containing tissues were typically characterized by a double emittance peak. In contrast, amyloid-free samples were characterized by fluorescence spectra with a single λmax value. Specimen collection site, age and sex did not appear to influence the morphology of electromagnetic spectra, which were generated for both amyloid-containing and amyloid-free tissue samples. The sensitivity of the fluorometric approach was ~78% and the specificity was 100%. Possible shortcomings of the technique may be due to the limit of detection of the instrument used.

Conclusions

Fluorescence spectroscopy may potentially be used as an effective, instantaneous and low-cost diagnostic tool for suspected secondary amyloidosis in patients affected with rheumatoid arthritis.