Raman spectral variation for human fingernails of postmenopausal women is dependent on fracture risk and osteoporosis status

Abstract

Patients diagnosed with osteoporosis have reported loss of fingernail resilience as the disease progresses. Keratin is the predominant protein in human nail tissue, and its structure has been postulated to be different in fingernails clipped from subjects who have sustained fragility fractures and those who have not, which may offer a window into the donor's bone health. This study was designed to qualify these differences, which may lead to the development of a novel screening tool for fracture risk. Raman spectroscopy was used to measure the fingernails of 633 postmenopausal women who presented at six fracture clinics located across the UK and Ireland. The Raman signals from donor's fingernails were compared between (1) fracture and nonfracture and (2) osteoporotic versus non‐osteoporotic donors The data presented show differences in the protein changes observed for pervasive osteoporosis compared to a general increased risk of fragility fracture. For fracture risk, compositional changes falling into broad classes of amino acid residue (aliphatic, aromatic, acidic, amide and sulphurous) were observed, while a difference in disulphide bonding levels was reaffirmed. For pervasive osteoporosis, the disulphide mode suggested increasing disorder in disulphide bonding orientation. Fractures were associated with a transition from alpha helical secondary structure to random, while the pervasive osteoporosis cases were associated with a transition to beta sheet structure. General fracture risk is associated with a change in the structure and composition of the keratin protein. Osteoporosis is associated with different protein structural changes and an increase in free acid groups. Copyright © 2017 John Wiley & Sons, Ltd.

A Preliminary Evaluation of the Ability of Keratotic Tissue to Act as a Prognostic Indicator of Hip Fracture Risk

“…The use of nail tissue, rather than bone, could possibly provide a simpler means of assessing fracture risk. Previous studies by the authors have hypothesised a relationship between human nail structure, osteoporosis, and fracture risk [9][10][11][12][13][14] due to common exposure to systemic factors for bone and nail. These studies have used Raman spectroscopy, an optical analytical technique for obtaining semi-quantitative and qualitative information on complex samples.…”

Recent advances in linear and nonlinear Raman spectroscopy. Part XII

“…Beattie et al reported that Raman spectral variations of human fingernails of postmenopausal women is dependent on fracture risk and osteoporosis status. They find that general fracture risk is associated with a change in the structure and composition of keratin protein, whereas osteoporosis is associated with different protein structural changes and an increase in free acid groups . Buchwald, Okulus, and Szybowicz reported new insights into Raman spectroscopy as a tool of early dental caries detection.…”

Nail Properties and Bone Health: A Review

“…The discrepant results may be due to the lack of a proper spectra baseline correction model. Positive relationships have been demonstrated by Beattie et al [ 36 ], who developed a baseline correction model using a singular value decomposition (SVD)-based method.…”

“…Using a baseline spectra correction model, Beattie and associates evaluated the amino acid profile of nail keratin samples from both fracture and non-fracture samples [ 36 ]. The keratin from the fracture group had no evidence of S–S bonds and had a low content of basic and hydroxyl amino acids compared to the control samples.…”

“…Raman spectroscopy may also be a valuable method to identify those at risk of fracture. Two recent studies [ 36 , 39 ] have collected nail samples from 633 postmenopausal British and Irish women and analysed them using Raman spectroscopy. Forty-two percent of the tested population experienced a fracture due to fragility.…”