Diffuse reflectance spectroscopy
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Caffeine is the most widely consumed psychoactive substance worldwide, affecting numerous tissues and organs, with notable impacts on the central nervous system, heart, and blood vessels. The effect of caffeine on vascular smooth muscle cells is an initial transient contraction followed by significant vasodilatation. In this study we investigate the use of diffuse reflectance spectroscopy (DRS) for monitoring of vascular changes in human skin induced by caffeine consumption. DRS spectra were recorded on volar sides of the forearms of eight healthy volunteers at time intervals of 0, 30, 60, 120, and 180 min after consumption of caffeine, while one subject served as a negative control. Analytical diffusion approximation solutions for diffuse reflectance from three-layer structures were used to assess skin composition (e.g. dermal blood volume fraction and oxygen saturation) by fitting these solutions to experimental data. The results demonstrate that cutaneous vasodynamics induced by caffeine consumption can be monitored by DRS, while changes in the control subject not consuming caffeine were insignificant.
- MeSH
- kofein * MeSH
- kůže * krevní zásobení MeSH
- lidé MeSH
- spektrální analýza metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Changes in the protonation state of lyophilized proteins can impact structural integrity, chemical stability, and propensity to aggregate upon reconstitution. When a buffer is chosen, the freezing/drying process may result in dramatic changes in the protonation state of the protein due to ionization shift of the buffer. In order to determine whether protonation shifts are occurring, ionizable probes can be added to the formulation. Optical probes (dyes) have shown dramatic ionization changes in lyophilized products, but it is unclear whether the pH indicator is uniform throughout the matrix and whether the change in the pH indicator actually mirrors drug ionization changes. In solid-state NMR (SSNMR) spectroscopy, the chemical shift of the carbonyl carbon in carboxylic acids is very sensitive to the ionization state of the acid. Therefore, SSNMR can be used to measure ionization changes in a lyophilized matrix by employing a small quantity of an isotopically-labeled carboxylic acid species in the formulation. This paper compares the apparent pH of six trehalose-containing lyophilized buffer systems using SSNMR and UV-Vis diffuse reflectance spectroscopy (UVDRS). Both SSNMR and UVDRS results using two different ionization probes (butyric acid and bromocresol purple, respectively) showed little change in apparent acidity compared to the pre-lyophilized solution in a sodium citrate buffer, but a greater change was observed in potassium phosphate, sodium phosphate, and histidine buffers. While the trends between the two methods were similar, there were differences in the numerical values of equivalent pH (pHeq) observed between the two methods. The potential causes contributing to the differences are discussed.
- MeSH
- fosfáty * chemie MeSH
- histidin * chemie MeSH
- koncentrace vodíkových iontů MeSH
- kyselina citronová chemie MeSH
- lyofilizace * metody MeSH
- magnetická rezonanční spektroskopie * metody MeSH
- pufry MeSH
- spektrofotometrie ultrafialová metody MeSH
- trehalosa * chemie MeSH
- Publikační typ
- časopisecké články MeSH
Matija MILANIC1,2, Rok HREN1,3,4, Jost STERGAR1,2, Urban SIMONCIC1,2 1Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Republic of Slovenia, 2Jožef Stefan Institute, Ljubljana, Republic of Slovenia, 3Institute of Mathematics, Physics, and Mechanics, Ljubljana, Republic of Slovenia, 4Syreon Research Institute, Budapest, Hungary Physiol Res 2024 Mar 11;73(1):47-56. doi: 10.33549/physiolres.935138. PMID: 38466004 This paper has been retracted on the base of author ́s request.
- MeSH
- dospělí MeSH
- kofein * aplikace a dávkování MeSH
- kůže * účinky léků MeSH
- lidé MeSH
- mladý dospělý MeSH
- spektrální analýza metody MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
This in vitro study aimed to compare outcomes of dental caries detection using visual inspection classified according to the International Caries Detection and Assessment System (ICDAS) with objective assessments using a well-established laser fluorescence system (Diagnodent pen) and a novel diffuse reflectance spectroscopy (DRS) device. One hundred extracted permanent premolars and molars were utilized, including sound teeth, teeth with non-cavitated caries, or teeth with small cavitated lesions. A total of 300 regions of interest (ROIs) were assessed using each detection method. Visual inspection, being a subjective method, was performed by two independent examiners. The presence and extent of caries were histologically verified according to Downer's criteria, serving as a reference for other detection methods. Histological results revealed 180 sound ROIs and 120 carious ROIs, categorized into three different extents of caries. Overall, there was no significant difference between the detection methods in sensitivity (0.90-0.93) and false negative rate (0.05-0.07). However, DRS exhibited superior performance in specificity (0.98), accuracy (0.95), and false positive rate (0.04) compared to other detection methods. Although the tested DRS prototype device exhibited limited penetration depth, it shows promise as a method, particularly for the detection of incipient caries.
- Publikační typ
- časopisecké články MeSH
OBJECTIVES: A prospective quantitative MR study of brain tumours was performed to show the potential of combining different MR techniques to distinguish various disease processes in routine clinical practice. METHODS: Twenty-three patients with various intracranial tumours before treatment (diagnosis confirmed by a biopsy) and 59 healthy subjects were examined on a 3-T system by conventional MR imaging, 1H spectroscopic imaging, diffusion tensor imaging and T2 relaxometry. Metabolic concentrations and their ratios, T2 relaxation times and mean diffusivities were calculated and correlated on a pixel-by-pixel basis and compared to control data. RESULTS: Different tumour types and different localisations revealed specific patterns of correlations between metabolic concentrations and mean diffusivity or T2 relaxation times. The patterns distinguish given tissue states in the examined area: healthy tissue, tissue infiltrated by tumour, active tumour, oedema infiltrated by tumour, oedema, etc. This method is able to describe the complexity of a highly heterogeneous tissue in the tumour and its vicinity, and determines crucial parameters for tissue differentiation. CONCLUSIONS: A combination of different MR parameters on a pixel-by-pixel basis in individual patients enables better identification of the tumour type, direction of proliferation and assessment of the tumour extension. KEY POINTS : * Magnetic resonance offers many different methods of examining the brain. * A combination of quantitative MR parameters helps distinguish different brain lesions * Different tumour types revealed specific correlation patterns amongst different MR parameters * The correlation patterns reflect highly heterogeneous complex tissue within tumours.
- MeSH
- biopsie metody MeSH
- difuze MeSH
- dospělí MeSH
- edém patologie MeSH
- gliom MeSH
- lidé středního věku MeSH
- lidé MeSH
- magnetická rezonanční spektroskopie metody MeSH
- magnetická rezonanční tomografie metody MeSH
- mapování mozku metody MeSH
- mozek patologie MeSH
- nádory mozku diagnóza patologie MeSH
- počítačové zpracování obrazu MeSH
- senioři MeSH
- studie případů a kontrol MeSH
- zobrazování difuzních tenzorů metody MeSH
- Check Tag
- dospělí MeSH
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- práce podpořená grantem MeSH
Contrary to the planktonic state of bacteria, their biofilm form represents severe complications in areas such as human medicine or food industry due to the increasing resistance against harsh conditions and treatment. In the present study, infrared attenuated total reflection (IR-ATR) spectroscopy has been applied as an analytic tool studying Escherichia coli ( E. coli) biofilm formation close to real time. We report on IR spectroscopic investigations on the biofilm formation via ATR waveguides probing the biofilm in the spectral window of 1800-900 cm-1 at dynamic flow conditions, which facilitated monitoring the growth dynamics during several days. Key IR bands are in the range 1700-1590 cm-1 (amide I), 1580-1490 cm-1 (amide II), and 1141-1006 cm-1 extracellular polymeric substances (EPS), which were evaluated as a function of time. Cyclic fluctuations of the amide I and amide II bands and a continuous increase of the EPS band were related to the starvation of bottom-layered bacteria caused by the nutrient gradient. Potential death of bacteria may then result in cannibalistic behavior known for E. coli colonies. Observing this behavior via IR spectroscopy allows revealing these cyclical changes in bottom-layered bacteria within the biofilm under continuous nutrient flow, in molecular detail, and during extended periods for the first time.
Lanthanum-modified TiO2 photocatalysts (0.2-1.5 wt% La) were investigated in the methanol decomposition in an aqueous solution. The photocatalysts were prepared by the common sol-gel method followed by calcination. The structural (X-ray diffraction, Raman, X-ray photoelectron spectroscopy), textural (N2 physisorption), and optical properties (diffuse reflectance spectroscopy, photoelectrochemical measurements) of all synthetized nanomaterials were correlated with photocatalytic activity. Both pure TiO2 and La-doped TiO2 photocatalysts proved higher yields of hydrogen in comparison to photolysis. The photocatalyst with optimal amount of lanthanum (0.2 wt% La) showed almost two times higher amount of hydrogen produced at the same time as in the presence of pure TiO2. The photocatalytic activity increased with both increasing photocurrent response and decreasing amount of lattice and surface O species. It has been shown that both direct and indirect mechanisms of methanol photocatalytic oxidation participate in the production of hydrogen. Both direct and indirect mechanisms take part in the formation of hydrogen.
Although the nitrous oxide belongs among three of the most contributing greenhouse gases to global warming, it is quite neglected by photocatalytic society. The g-C3N4 and WO3 composites were therefore tested for the photocatalytic decomposition of N2O for the first time. The pure photocatalysts were prepared by simple calcination of precursors, and the composites were prepared by mixing of suspension of pure components in water followed by calcination. The structural (X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy), textural (N2 physisorption), and optical properties (diffuse reflectance spectroscopy, photoluminescence spectroscopy, photoelectrochemical measurements) of all composites were correlated with photocatalytic activity. The experimental results and results from characterization techniques confirmed creation of Z-scheme in the WO3/g-C3N4 composites, which was confirmed by hydroxyl radicals' trapping measurements. The photocatalytic decomposition of N2O was carried out in the presence of UVA light (peak intensity at 365 nm) and the 1:2 WO3/g-C3N4 composite was the most active one, but the photocatalytic activity was just negligibly higher than that of pure WO3. This is caused by relatively weak interaction between WO3 and g-C3N4 which was revealed from XPS.
Biofilms are complex microbial communities that tend to attach to either biotic or abiotic surface. Enclosed in a self-produced extracellular polymeric substance (EPS) matrix, the biofilms often cause persistent infections. The objective of this study was to investigate the antibiofilm activity of dimethyl sulfoxide (DMSO) and afatinib against Gram-negative pathogens. Test microorganisms used in this study were Escherichia coli ATCC 1299, Pseudomonas aeruginosa ATCC 10145, and Salmonella typhimurium ATCC 14028. Biofilms were developed in 96-well microplate at 37°C for 24 h. Following removal of non-adherent cells, analysis of biofilm viability, biofilm biomass, and extracellular polymeric substances (EPS) matrix were performed using resazurin assay, crystal violet assay, and attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, respectively. Bradford protein assay was conducted to determine the total amount of EPS proteins. The results demonstrated that both 32% DMSO alone and its combination with 3.2 μg/mL afatinib were effective in killing biofilm cells and reducing biofilm biomass. IR spectral variations of EPS matrix of biofilms in the range between 1700 and 900 cm-1 were also observed. Reduction in EPS proteins verified the chemical modifications of EPS matrix. In conclusion, 32% DMSO alone and its combination with 3.2 μg/mL afatinib showed remarkable antibiofilm activities against Gram-negative pathogens. It was suggested that the biofilm inhibition was mediated by the chemical modification of EPS matrix.
- MeSH
- antibakteriální látky farmakologie MeSH
- biofilmy účinky léků MeSH
- chinazoliny farmakologie MeSH
- dimethylsulfoxid farmakologie MeSH
- Escherichia coli účinky léků fyziologie MeSH
- Pseudomonas aeruginosa účinky léků fyziologie MeSH
- Salmonella typhimurium účinky léků fyziologie MeSH
- spektroskopie infračervená s Fourierovou transformací MeSH
- synergismus léků MeSH
- Publikační typ
- časopisecké články MeSH
Optimální volba léčby pacientů s tumorem z hlediska její úspěšnosti je podmíněna správnou a přesnou diagnózou. Přestože zobrazování pomocí magnetické rezonance, počítačové tomografie či pozitron-elektronové transmise jsou již delší dobu používány v klinické praxi jako uznávané diagnostické metody, v případech intralebečních tumorů to jsou kombinace těchto metod s protonovou MR spektroskopií (1H MR), které přinášejí přesnější informace o povaze a rozsahu postižení. 1H MR spektroskopie neinvazivně poskytuje informace o biochemických pochodech v tumoru. Tento souborný článek shrnuje dostupné poznatky o metabolických změnách v jednotlivých typech tumorů či jiných patologií v lidském mozku projevujících se ve spektrech magnetické rezonance a zabývá se současnými možnostmi využití kombinace několika MR diagnostických metod (MR zobrazování, spektroskopie, difuzometrie, relaxometrie) pro upřesnění rozsahu patologického procesu, jehož znalost je významná pro vhodné plánování terapie.
Making the best treatment choice for patients with a tumour with respect to its success requires correct and precise diagnosis. Even though magnetic resonance, computer tomography and positron emission tomography have been for some time used in clinical practice as well-established diagnostic methods, it is a combination of these methods with proton MR spectroscopy (1H MR) that provides more precise information about the nature and extent of impairment in patients with intracranial tumours. The non-invasive 1H MR spectroscopy provides information on biochemical processes in the tumour. This review paper summarises the existing knowledge on metabolic changes in the different types of tumours or other pathologies of the human brain reflected through magnetic resonance spectra and is concerned with the options currently available for using a combination of several MR diagnostic methods (MR imaging, spectroscopy, diffusimetry, relaxometry) to determine the extent of pathological process, the knowledge of which is important for planning of an appropriate therapy.
- Klíčová slova
- MR spektroskopie, MR difuze, korelace metod,
- MeSH
- artefakty MeSH
- astrocytom diagnóza metabolismus patologie MeSH
- diferenciální diagnóza MeSH
- difuzní magnetická rezonance metody přístrojové vybavení MeSH
- financování organizované MeSH
- glioblastom diagnóza metabolismus patologie MeSH
- gliom diagnóza metabolismus patologie MeSH
- lidé MeSH
- lymfom diagnóza metabolismus patologie MeSH
- magnetická rezonanční spektroskopie metody přístrojové vybavení MeSH
- magnetická rezonanční tomografie metody využití MeSH
- meningeom diagnóza metabolismus patologie MeSH
- metabolické nemoci mozku diagnóza etiologie MeSH
- metastázy nádorů diagnóza patologie MeSH
- nádory mozku diagnóza etiologie patologie MeSH
- obsah radioaktivních látek v organizmu MeSH
- statistika jako téma MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- přehledy MeSH
