Raman Spectroscopy identifies differences in ochronotic and non-ochronotic cartilage; a potential novel technique for monitoring ochronosis

OBJECTIVE

Alkaptonuria (AKU) is a rare, inherited disorder of tyrosine metabolism, where patients are unable to breakdown homogentisic acid (HGA), which increases systemically over time. It presents with a clinical triad of features; HGA in urine, ochronosis of collagenous tissues, and the subsequent ochronotic arthritis of these tissues. In recent years the advance in the understanding of the disease and the potential treatment of the disorder looks promising with the data on the efficacy of nitisinone. However, there are limited methods for the detection and monitoring of ochronosis in vivo, or for treatment monitoring. The study aim was to test the hypothesis that Raman spectra would identify a distinct chemical fingerprint for the non-ochronotic, compared to ochronotic cartilage.

DESIGN

Ochronotic and non-ochronotic cartilage from human hips and ears were analysed using Raman spectroscopy.

RESULTS

Non-ochronotic cartilage spectra were similar and reproducible and typical of normal articular cartilage. Conversely, the ochronotic cartilage samples were highly fluorescent and displayed limited or no discernible Raman peaks in the spectra, in stark contrast to their non-ochronotic pairs. Interestingly, a novel peak was observed associated with the polymer of HGA in the ochronotic cartilage that was confirmed by analysis of pigment derived from synthetic HGA.

CONCLUSION

This technique reveals novel data on the chemical differences in ochronotic compared with non-ochronotic cartilage, these differences are detectable by a technique that is already generating in vivo data and demonstrates the first possible procedure to monitor the progression of ochronosis in tissues of patients with AKU.

Correction to: Compressive loading of the murine tibia reveals site-specific micro-scale differences in adaptation and maturation rates of bone

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Compressive loading of the murine tibia reveals site-specific micro-scale differences in adaptation and maturation rates of bone

Loading increases bone mass and strength in a site-specific manner; however, possible effects of loading on bone matrix composition have not been evaluated. Site-specific structural and material properties of mouse bone were analyzed on the macro- and micro/molecular scale in the presence and absence of axial loading. The response of bone to load is heterogeneous, adapting at molecular, micro-, and macro-levels.

INTRODUCTION

Osteoporosis is a degenerative disease resulting in reduced bone mineral density, structure, and strength. The overall aim was to explore the hypothesis that changes in loading environment result in site-specific adaptations at molecular/micro- and macro-scale in mouse bone.

METHODS

Right tibiae of adult mice were subjected to well-defined cyclic axial loading for 2 weeks; left tibiae were used as physiologically loaded controls. The bones were analyzed with μCT (structure), reference point indentation (material properties), Raman spectroscopy (chemical), and small-angle X-ray scattering (mineral crystallization and structure).

RESULTS

The cranial and caudal sites of tibiae are structurally and biochemically different within control bones. In response to loading, cranial and caudal sites increase in cortical thickness with reduced mineralization (-14 and -3%, p < 0.01, respectively) and crystallinity (-1.4 and -0.3%, p < 0.05, respectively). Along the length of the loaded bones, collagen content becomes more heterogeneous on the caudal site and the mineral/collagen increases distally at both sites.

CONCLUSION

Bone structure and composition are heterogeneous, finely tuned, adaptive, and site-specifically responsive at the micro-scale to maintain optimal function. Manipulation of this heterogeneity may affect bone strength, relative to specific applied loads.

Aberrant semantic and affective processing in people at risk for psychosis

Semantic and affective processing were examined in people at risk for psychosis. The participants were 3 groups of college students: 41 people with elevated Perceptual Aberration and Magical Ideation (PerMag) scores, 18 people with elevated Social Anhedonia (SocAnh) scores, and 100 control participants. Participants completed a single-word, continuous presentation pronunciation task that included semantically related words, affectively valenced words, and semantically unrelated and affectively neutral words. PerMag participants exhibited increased semantic priming and increased sensitivity to affectively valenced primes. SocAnh participants had increased sensitivity to affectively valenced targets.

Aberrant semantic and affective processing in people at risk for psychosis

Semantic and affective processing were examined in people at risk for psychosis. The participants were 3 groups of college students: 41 people with elevated Perceptual Aberration and Magical Ideation (PerMag) scores, 18 people with elevated Social Anhedonia (SocAnh) scores, and 100 control participants. Participants completed a single-word, continuous presentation pronunciation task that included semantically related words, affectively valenced words, and semantically unrelated and affectively neutral words. PerMag participants exhibited increased semantic priming and increased sensitivity to affectively valenced primes. SocAnh participants had increased sensitivity to affectively valenced targets.

Word production in schizophrenia and its relationship to positive symptoms

We explored relationships between positive symptoms of schizophrenia and neurocognitive functions (language and memory). The semantic and phonemic associations among words produced in a verbal fluency task by 26 participants diagnosed with DSM-III-R schizophrenia were examined. Formal thought disorder was associated with producing fewer contextually related words and with producing more unrelated words. In contrast, hallucinations were associated with producing more related words. Our results suggest associations between formal thought disorder and impaired memory, and between hallucinations and increased lexical activation/excessive synaptic pruning.