RESEARCH OF HUMAN BLOOD OPTICAL PROPERTIES WITH CONCENTRATION CHANGES OF BLOOD COMPONENTS IN TERAHERTZ FREQUENCY RANGE

Subject of Research.The paper presents the study of blood biochemical composition (bilirubin, creatinine, triglycerides, uric acid) effect on its optical properties, refractive index and absorption coefficient, in terahertz frequency range. Method. To obtain the values of the refractive index and the absorption coefficient, the method of terahertz time-domain spectroscopy was used in the transmission mode. Concentrations of total bilirubin, creatinine and triglycerides were measured in blood serum by the colorimetric method, the pseudokinetic method and the enzymatic method, respectively. The glucose level was determined in blood plasma by the enzyme method. All measurements of blood component concentrations were carried out at the Almazov National Medical Research Centre. Main Results. The optical properties of blood with various biochemical composition were obtained using terahertz time-domain spectroscopy at the frequency of 0.4THz. It is shown that the refractive indices and the absorption coefficients of blood decrease with an increase in the concentration of bilirubin and creatinine. It has also been found that with an increase in the concentration of uric acid and triglycerides, the refractive index of blood increases and the absorption coefficient of blood decreases, respectively. The correlation between the refractive index and the concentration of triglycerides and the correlation between the blood absorption coefficient and the concentration of uric acid were not revealed. Practical Relevance. The observed correlations between the concentrations of blood components and the optical properties are useful in the development of a new technique for blood analysis

Vitamin D deficiency is a risk factor for obesity and diabetes type 2 in women at late reproductive age

It was suggested that glucose metabolism and body fat content depend on serum levels of 25-hydroxyvitamin D [25(OH)D]. We studied 320 healthy women at late reproductive age of 40 to 52 years old (mean age 46.1±4.5) from St. Petersburg (North-West region of Russia). 25(OH)D levels were from 19.4 to 134.0 nMol/L (mean 52.9±22.7). Vitamin D deficiency (lower than 50 nMol/L) and insufficiency (50-75 nMol/L) was revealed in 59.1% and 27.8% of women, respectively. The study showed that low 25(OH)D levels were associated with obesity (r=-0.35,