This work shows the application of LSCI for mapping the cerebral vessels of a laboratory animal, and also presents the time-frequency processing of the registered signal. Thus, we expand the capabilities of the existing LSCI approach and demonstrate spatial mapping of blood flow fluctuations.
The article is devoted to the analysis of skin perfusion oscillation processes with wild-type and synuclein-deficient mice with three knockout (KO) types: αγ-KO, β-KO, and αβγ-KO. The role of synucleins in tissues that exclude the central nervous system remains sparsely studied. Laser Doppler flowmetry was used to investigate the potential involvement of synucleins in murine microcirculation functioning This method is widely used to analyze microcirculatory disturbances in a variety of pathologies and has proven to be sensitive to the manifestation of abnormalities of normal function. The study revealed that deficiency of β-synuclein affects oscillation processes more than αγ-synuclein deficiency.
NADH is one of the central signalling molecules that serve as a substrate for many vital processes, in particular, is a donor for the electron transport chain in mitochondria. At the same time, mitochondrial activity and the intensity of metabolic processes in the tissues of different brain regions drastically differ. This work aimed to compare the NAD(P)H production rate in the tissues of various brain regions (cortex, cerebellum, hippocampus, brainstem) assessed by the parameters of dynamics of its autofluorescence. We studied acute slices of the rat brain of the corresponding regions. The intensity of NAD(P)H autofluorescence and its rate of production was determined to assess the activity of mitochondria. Whereafter the slices were analysed by histological examination. It has been observed that mitochondrial activity in hippocampal tissues is significantly higher than in other brain regions, which may be associated with more complex cognitive functions of the hippocampus in mammals. The results of this research can help explain the selectivity of hippocampal lesions during ischemic injuries and neurodegenerative diseases.
To determine optimal lighting conditions for contrast imaging of surgical objects, optical characteristics of biological tissues and spectral characteristics of smart light "LED light" source based on RGBW LED are compared. The spectral characteristics of tissues and organs have been investigated. Optimal lighting conditions for contrast imaging of biological tissues during surgery were studied. The optimal colour of light for working with individual organs against the background of the whole organism is selected. Perspective of light fixture application with the possibility of dynamic colour control is shown.
The paper describes the results of experimental studies using custom developed optical biopsy system for diagnostics in vivo during the procedure of fine needle aspiration biopsy. Experimental studies were conducted in laboratory mice with inoculated hepatocellular carcinoma. The measurements were carried out using fluorescence spectroscopy and diffuse reflectance spectroscopy methods to reveal metabolic and morphological changes in tissues. The results show that the developed approach is sensitive for cancer detection. Quantified differences in the maximum of fluorescence spectra and diffuse reflectance spectra between tumor and normal tissues were demonstrated and approved with morphological analysis.
The aim of the study was to compare the metabolic activity of brain cortex after the acute hypoxia caused by the impairment of breathing or blood circulation. Male Wistar rats were randomized in two groups: impaired breathing and blood circulation failure groups. Fluorescence under 365 and 450 nm excitation and diffuse reflectance intensity at 550-820 nm range were estimated. We found that after long-term hypoxic conditions, notable metabolic changes occur. We suppose that oxygen deficiency causes an activation of the GABA shunt mechanism. In cases of blood circulation failure, fluorescence intensity changes faster than in cases of breathing impairment.
The paper describes the methodology and technical implementation of a multimodal approach for optical diagnostics in hepatopancreatobiliary organs focal and diffuse neoplasms. Fine needle aspiration biopsy technique and following cytological examination show its effectiveness and safety but its performing takes several days. However, the problem of real-time analysis of pathological changes in tissues remains relevant. The solution suggested is implementing of optical biopsy methods (namely fluorescence spectroscopy and diffuse reflectance spectroscopy) in the form of fiber-optic probe compatible with standard biopsy fine needles. The special device was designed for this purpose to conduct optical measurements and compare the results with ones obtained by conventional biopsy. The proposed methodology seems promising for developing new diagnostic criteria for clinical practice.
Diagnosis and treatment of acute destructive pancreatitis is one of the most urgent problems of abdominal surgery. To obtain additional diagnostic information about the microcirculation state and metabolic processes, various imaging techniques are widely used during surgical interventions. One of the most perspective techniques for in vivo microcirculation assessment is laser speckle-contrast imaging (LSCI), allowing for evaluation of blood perfusion. The experimental results showed the possibility to evaluate the blood perfusion of the mouse pancreas in the simulation of ischemia using the LSCI method.
Fine needle aspiration biopsy technique and following histological examination show its effectiveness and safety but its performing takes several time. However, the problem of real-time analysis of pathological changes in tissues remains relevant. We demonstrate optical fine-needle biopsy method, combining a fine needle (17.5G) and a fiber-optic probe (1 mm diameter) for minimally invasive interrogation of tissue in vivo. During rat tumor experiment, we collected spectrally-resolved diffuse reflectance and fluorescence. Quantified differences between tumor and normal tissues were demonstrated and approved with morphological analysis. The proposed methodology seems promising for developing new diagnostic criteria for clinical practice.
This studiy was carried out on groups of clinically healthy male Wistar rats. Animals received distilled drinking water ad libitum for 1 month, water containing succinic acid, water containing zinc sulphate and succinate zinc. Using the method of fluorescence spectroscopy, the parameters of brain metabolism in vivo in a model of laboratory rats was investigated. Based on data obtained by fluorescence spectroscopy, we have registered a change in the degree of cellular respiration in different structures of the cerebral cortex with the toxic effect of zinc compounds and succinic acid on the oxygen exchange process.
Using fluorescence spectroscopy system with fibre-optical probe, we investigated the dynamics of propagation and circulation in the microcirculatory system of experimental nanocapsules fluorescent-labelled (rhodamine TRITC) nanocapsules. The studies were carried out in clinically healthy Wistar rats. The model animals were divided into control group and group received injections of the nanocapsules. The fluorescent measurements conducted transcutaneously on the thigh surface. The administration of the preparation with the rhodamine concentration of 5 mg/kg of animal weight resulted in twofold increase of fluorescence intensity by reference to the baseline level. As a result of the study, it was concluded that fluorescence spectroscopy can be used for transdermal measurements of the rhodamine-loaded capsules in vivo.
This article presents the results of the study of the pressure applied on optical diagnostic probes as a significant factor affecting the results of measurements. During stepwise increasing and decreasing of local pressure on skin we conducted measurements using the methods of laser Doppler flowmetry and fluorescence spectroscopy. It was found out that pressure on optical probe has sufficient impact on skin microcirculation to affect registered fluorescence intensity. Data obtained in this study are of interest for design and development of diagnostic technologies for wearable devices. This data will also inform further investigation into issues of compensation of blood absorption influence on fluorescence spectrum, allowing increased accuracy and reproducibility of measurements by fluorescence spectroscopy methods in optical diagnosis.
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