Serum Based Diagnosis of Asthma Using Raman Spectroscopy: An Early Phase Pilot Study

Abstract

The currently prescribed tests for asthma diagnosis require compulsory patient compliance, and are usually not sensitive to mild asthma. Development of an objective test using minimally invasive samples for diagnosing and monitoring of the response of asthma may help better management of the disease. Raman spectroscopy (RS) has previously shown potential in several biomedical applications, including pharmacology and forensics. In this study, we have explored the feasibility of detecting asthma and determining treatment response in asthma patients, through RS of serum. Serum samples from 44 asthma subjects of different grades (mild, moderate, treated severe and untreated severe) and from 15 reference subjects were subjected to Raman spectroscopic analysis and YKL-40 measurements. The force expiratory volume in 1 second (FEV1) values were used as gold standard and the serum YKL-40 levels were used as an additional parameter for diagnosing the different grades of asthma. For spectral acquisition, serum was placed on a calcium fluoride (CaF2) window and spectra were recorded using Raman microprobe. Mean and difference spectra comparisons indicated significant differences between asthma and reference spectra. Differences like changes in protein structure, increase in DNA specific bands and increased glycosaminoglycans-like features were more prominent with increase in asthma severity. Multivariate tools using Principal-component-analysis (PCA) and Principal-component based-linear-discriminant analysis (PC-LDA) followed by Leave-one-out-cross-validation (LOOCV), were employed for data analyses. PCA and PC-LDA results indicate separation of all asthma groups from the reference group, with minor overlap (19.4%) between reference and mild groups. No overlap was observed between the treated severe and untreated severe groups, indicating that patient response to treatment could be determined. Overall promising results were obtained, and a large scale validation study on random subjects is warranted before the routine clinical usage of this technique.

Raman spectroscopy for detection of imatinib in plasma: A proof of concept

“…16 This Raman system consists of laser (785 nm, Process Instruments) as an excitation source and HE-785 spectrograph (Horiba-JobinYvon, France) coupled with CCD (Synapse, HoribaJobin-Yvon) as dispersion and detection elements, respectively. Optical¯ltering of unwanted noise, including Rayleigh signals, is accomplished through \Superhead", the other component of the system.…”

“…Details of the spectral preprocessing are mentioned elsewhere. 16 Average spectra were computed from these background-subtracted and interpolated spectra. The typical spectra were baseline-corrected by¯tting a¯fth-order polynomial function using LabSpec 4.18 (Horiba Jobin Yvon, France).…”

Raman Spectroscopy of Experimental Oral Carcinogenesis

“…9 The RS, which can provide chemical fingerprint/ biochemical profile, has shown promising results in the diagnosis of several cancers, 8,[10][11][12][13][14][15] including oral cancers. [16][17][18][19][20][21][22][23][24][25] Both ex vivo and in vivo RS studies in oral cancers have shown classification of pathological conditions along with detection of confounding factors like age-related changes and early events like cancer field effects in oral cancer, 16,17,[21][22][23][24][25] demonstrating efficiency of the technique. Still, further studies in exploring sequential changes in oral carcinogenesis are warranted.…”

Raman Spectroscopy of Blood and Blood Components

“…190 Other diseases or conditions that have been studied using plasma include brain ischemia (insufficient blood flow to the brain), 191,192 hepatitis C (disease of the liver), 193 pemphigus vulgaris (skin disease) 194 and preeclampsia (a condition that can occur during pregnancy). 195 Early investigations of plasma in asthma (lung inflammation) 196 and Alzheimer's disease (a form of dementia) 197,198 have also been performed.…”