Time-domain NIRS system based on supercontinuum light source and multi-wavelength detection: Validation for tissue oxygenation studies

We present and validate a multi-wavelength time-domain near-infrared spectroscopy (TD-NIRS) system that avoids switching wavelengths and instead exploits the full capability of a supercontinuum light source by emitting and acquiring signals for the whole chosen range of wavelengths. The system was designed for muscle and brain oxygenation monitoring in a clinical environment. A pulsed supercontinuum laser emits broadband light and each of two detection modules acquires the distributions of times of flight of photons (DTOFs) for 16 spectral channels (used width 12.5 nm / channel), providing a total of 32 DTOFs at up to 3 Hz. Two emitting fibers and two detection fiber bundles allow simultaneous measurements at two positions on the tissue or at two source-detector separations. Three established protocols (BIP, MEDPHOT, and nEUROPt) were used to quantitatively assess the system's performance, including linearity, coupling, accuracy, and depth sensitivity. Measurements were performed on 32 homogeneous phantoms and two inhomogeneous phantoms (solid and liquid). Furthermore, measurements on two blood-lipid phantoms with a varied amount of blood and Intralipid provide the strongest validation for accurate tissue oximetry. The retrieved hemoglobin concentrations and oxygen saturation match well with the reference values that were obtained using a commercially available NIRS system (OxiplexTS) and a blood gas analyzer (ABL90 FLEX), except a discrepancy occurs for the lowest amount of Intralipid. In-vivo measurements on the forearm of three healthy volunteers during arterial (250 mmHg) and venous (60 mmHg) cuff occlusions provide an example of tissue monitoring during the expected hemodynamic changes that follow previously well-described physiologies. All results, including quantitative parameters, can be compared to other systems that report similar tests. Overall, the presented TD-NIRS system has an exemplary performance evaluated with state-of-the-art performance assessment methods

MODELING OF THE FORM OF BISMUTH ENERGY SPEKTRUM LINE BY CHANGING THE VALUES OF CYCLOTRON MASSES

The article gives an analysis of the optimal values of the cyclotron masses bismuth electrons by modeling of the coefficient by passing the planar waveguide in the far infrared region

Enzymatic Blockade of the Ubiquitin-Proteasome Pathway

Ubiquitin-dependent processes control much of cellular physiology. We show that expression of a highly active, Epstein-Barr virus-derived deubiquitylating enzyme (EBV-DUB) blocks proteasomal degradation of cytosolic and ER-derived proteins by preemptive removal of ubiquitin from proteasome substrates, a treatment less toxic than the use of proteasome inhibitors. Recognition of misfolded proteins in the ER lumen, their dislocation to the cytosol, and degradation are usually tightly coupled but can be uncoupled by the EBV-DUB: a misfolded glycoprotein that originates in the ER accumulates in association with cytosolic chaperones as a deglycosylated intermediate. Our data underscore the necessity of a DUB activity for completion of the dislocation reaction and provide a new means of inhibition of proteasomal proteolysis with reduced cytotoxicity.National Institutes of Health (U.S.)EMBO (long term Fellowship 2008-379)Boehringer Ingelheim Fond

Time-domain NIRS system based on supercontinuum light source and multi-wavelength detection: Validation for tissue oxygenation studies

We present and validate a multi-wavelength time-domain near-infrared spectroscopy (TD-NIRS) system that avoids switching wavelengths and instead exploits the full capability of a supercontinuum light source by emitting and acquiring signals for the whole chosen range of wavelengths. The system was designed for muscle and brain oxygenation monitoring in a clinical environment. A pulsed supercontinuum laser emits broadband light and each of two detection modules acquires the distributions of times of flight of photons (DTOFs) for 16 spectral channels (used width 12.5 nm / channel), providing a total of 32 DTOFs at up to 3 Hz. Two emitting fibers and two detection fiber bundles allow simultaneous measurements at two positions on the tissue or at two source-detector separations. Three established protocols (BIP, MEDPHOT, and nEUROPt) were used to quantitatively assess the system's performance, including linearity, coupling, accuracy, and depth sensitivity. Measurements were performed on 32 homogeneous phantoms and two inhomogeneous phantoms (solid and liquid). Furthermore, measurements on two blood-lipid phantoms with a varied amount of blood and Intralipid provide the strongest validation for accurate tissue oximetry. The retrieved hemoglobin concentrations and oxygen saturation match well with the reference values that were obtained using a commercially available NIRS system (OxiplexTS) and a blood gas analyzer (ABL90 FLEX), except a discrepancy occurs for the lowest amount of Intralipid. In-vivo measurements on the forearm of three healthy volunteers during arterial (250 mmHg) and venous (60 mmHg) cuff occlusions provide an example of tissue monitoring during the expected hemodynamic changes that follow previously well-described physiologies. All results, including quantitative parameters, can be compared to other systems that report similar tests. Overall, the presented TD-NIRS system has an exemplary performance evaluated with state-of-the-art performance assessment methods

SOME REGULARITIES OF OZONE DECOMPOSITION OVER NATURAL BENTONITE ANCHORED 3d METAL ACIDO COMPLEXES

Polyphasicity of both natural bentonite and catalysts based on the latter has been found by X-ray phase analysis and IR spectroscopy. In natural bentonite, the indentified phases were montmorillonite, α-quartz and calcite as an impurity. The formation of MCl2/N-Bent catalysts (M = Cu2+, Co2+, and Mn2+) does not lead to significant structural changes or to the formation of new phases from the catalyst components. However, an increase in a basal distance d001 for montmorillonite observed in this case can be evidence of the metal ion entering into its interlayer space because this increase agrees with the sizes of the metal ions (rCo < rCu < rMn). In the IR spectrum of natural bentonite, the bands assigned to stretching vibrations of OH groups bound with octahedral cations (M-OH) and to water molecules associated through hydrogen bonds are situated in the region 4000-3000 cm-1, the absorption bands of the silicate structure are concentrated in the region 1400-400 cm-1. The absorption band at 1421 cm-1 assigned to stretching vibrations of carbonate ion confirms calcite presence in this natural bentonite. Anchoring of Cu(II), Co(II) or Mn(II) chlorides onto natural bentonite results in a low-frequency shift of this absorption band. For the first time, the kinetics of the lowtemperature ozone decomposition over the MCl2/N-Bent compositions was investigated. It has been found that the CuCl2/N-Bent sample shows the lowest activity that can be explained by the thermodynamic forbiddenness of Cu(II) oxidation with ozone. The activity of the MnCl2/N-Bent and CoCl2/N-Bent samples depends on metal ion concentrations. Ozone decomposition over the MnCl2/N-Bent samples with CМnCl2 of 1.2∙10-6 and 2.4∙10-4 mol/g was effective only at the initial stage of the ozone-air mixture, OAM, passage through the sample, whereas, for CoCl2/N-Bent samples, the kinetic curve portions parallel to x-axis indicated that the steady state mode was settled. At CСоCl2= 2.4∙10-4 mol/g, C f O3 was 47 mg/m3 (CinO3 = 100 mg/m3) even in 30 h of the OAM passage. Thus, it has been found that the catalytic activity of the MCl2/N-Bent samples towards the ozone decomposition changes in the orders: at CМnCl2= 1.2∙10-6 mol/g: N-Bent < СuСl2/N-Bent < CoСl2/N-Bent < MnСl2/N-Bent (І), at CМnCl2= 2.4∙10-6 mol/g: N-Bent < СuСl2/N-Bent << MnСl2/N-Bent < CoСl2/N-Bent (ІІ)

Depth-resolved assessment of changes in concentration of chromophores using time-resolved near-infrared spectroscopy: estimation of cytochrome-c-oxidase uncertainty by Monte Carlo simulations

Time-resolved near-infrared spectroscopy (TR-NIRS) measurements can be used to recover changes in concentrations of tissue constituents (ΔC) by applying the moments method and the Beer-Lambert law. In this work we carried out the error propagation analysis allowing to calculate the standard deviations of uncertainty in estimation of the ΔC. Here, we show the process of choosing wavelengths for the evaluation of hemodynamic (oxy-, deoxyhemoglobin) and metabolic (cytochrome-c-oxidase (CCO)) responses within the brain tissue as measured with an in-house developed TR-NIRS multi-wavelength system, which measures at 16 consecutive wavelengths separated by 12.5 nm and placed between 650 and 950 nm. Data generated with Monte Carlo simulations on three-layered model (scalp, skull, brain) for wavelengths range from 650 to 950 nm were used to carry out the error propagation analysis for varying choices of wavelengths. For a detector with a spectrally uniform responsivity, the minimal standard deviation of the estimated changes in CCO within the brain layer, σ∆CbrainCCO = 0.40 µM, was observed for the 16 consecutive wavelengths from 725 to 912.5 nm. For realistic a detector model, i.e. the spectral responsivity characteristic is considered, the minimum, σ∆CbrainCCO = 0.47 µM, was observed at the 16 consecutive wavelengths from 688 to 875 nm. We introduce the method of applying the error propagation analysis to data as measured with spectral TR-NIRS systems to calculate uncertainty of recovery of tissue constituents concentrations