Comments on recent reports on infrared spectral detection of disease markers in blood components

Abstract

The search for disease markers in whole blood, or easily accessible blood components by spectral methods is a highly important aspect in the field of biophotonic research for disease diagnostics and screening, since it promises a minimally invasive approach to assess an individual's state of health. Fourier transform infrared spectroscopy, in particular, promises to be a fast, inexpensive method to search for markers of disease, since it detects variation in the proteome, lipidome and metabolome of biofluids, or activation of immune cells. However, the analysis of any materials by spectral methods is confounded by external factors such as those related to sample deposition and data acquisition, and by inherent variations in blood plasma concentration of small molecules (lactate, carbonate, phosphate, glucose) that varies between individual subjects and even for a given individual, as a function of time. Furthermore, observed differences in spectral patterns between patient samples and the control group may be due to the body's immune response (in particular, to the albumin to globulin ratio) and therefore, may not be specific to disease. These factors need to be accounted for in any effort to reliably detect much smaller variations in the concentration of disease-specific markers.

Fourier transform infrared spectroscopic signature of blood plasma in the progression of breast cancer with simultaneous metastasis to lungs

“…The analysis of plasma by spectroscopic methods may be also straitened due to the different factors such as too low concentrations of small molecules in comparison to content of proteins and biological fluctuations in blood between subjects [29]. In addition, experimental factors such the way of sample deposition and possibility of vapor spectral contributions to the amide I region should be considered [29]. But slight variations among numerous spectra per each group collected in this work and also negative results of water vapor test, we rather exclude a strong effect of some of these factors on our analysis.…”

New insights into hidradenitis suppurativa diagnosis via salivary infrared biosignatures: A pilot study

“…These HS patients had comorbidities, more importantly than for other HS patients. These comorbidities corresponded to Crohn's disease, spondyloarthropathy, fibromyalgia or asthma and are likely to induce spectral confounding interferences with infrared markers of HS [16, 38, 42, 43]. Six of these seven misclassified HS patients presented also periodontal disease, while 28 patients of all HS patients (n = 41) had this inflammatory oral disease.…”

Rapid diagnosis of infection etiology in febrile pediatric oncology patients using infrared spectroscopy of leukocytes

“…The leukocytes spectral differences between controls and infected categories are larger than the spectral differences between viral and bacterial infected patients. However, these changes are masked by other components of the plasma due to its complexity [50,75]. For the classification between controls and infected patients, 100% classification success was achieved when XGBoost classifier was applied, while other classifies achieved 99% of success.…”

“…The plasma contains some changes due to the reaction of the immune system as reflected from the different classifiers based on the plasma data summarized in Table S2. However, these changes are masked by other components of the plasma due to its complexity [50,75]. Sometimes, the desired biomarker is known and can be isolated from the plasma by immunochemical methods.…”