Spectroscopy - Volume 19, issue 5-6

Authors: Gagnon, R.E. | Macnab, A.J.

Article Type: Research Article

Abstract: Since clinical near infrared spectrophotometers (NIRS) first became commercially available in the early 1990's there have been more than two thousand related peer reviewed reports in the medical literature. These encompass a wide range of human and animal trials that have been directed at validating the principles, methods, and algorithms underlying the technology, as well as demonstrating its potential for specific clinical uses such as detecting concealed bleeding, onset of hypoxia, progress of ischemia, and tissue oxygenation status within human brain, muscles, organs, and tumours. In addition to its standard use as a monitor of patterns of change in the …concentrations of oxygenated, and de-oxygenated hemoglobin residing in blood, NIRS has also been used to monitor patterns of change in the redox status of the cellular respiration enzyme, cytochrome c oxidase (Cyt a,a3 ) which utilizes the oxygen diffused from the blood. Accompanied by a tracer bolus of near infrared absorbing dye, NIRS has also been used to measure the proportional blood flow and blood volume transiting organs. NIRS has been used in conjunction with PET, fMRI, BOLD-fMRI, TCD, vascular flowmetry, MRS, NMR, plethysmography, PO2 histography, EEG, ECG, EMG, SSEP, MEP, MEG, and standard bedside monitoring devices. Herein we summarize the history, technique, algorithms, methods and advances of clinical NIRS. Show more

Keywords: Spectrophotometry, cytochrome, hemoglobin, adenosine triphosphate, phosphorylation, mitochondria

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 221-233, 2005

Authors: Mindukshev, Igor V. | Jahatspanian, Igor E. | Goncharov, Nikolay V. | Jenkins, Richard O. | Krivchenko, Alexander I.

Article Type: Research Article

Abstract: A new method is presented for simultaneous monitoring of changes in shape and aggregation of platelets. The signal of light scattering alterations at angles below six degrees was shown to be determined by platelet aggregation dynamics (aggregation, disaggregation, coagulation). Over a range of larger angles (6–15 degrees), cell shape changes also contributed to the signal: (i) spherization, and (ii) pseudopodia formation. The first stage was shown to be fast (t1/2 of few seconds) and correlated with [Ca2+ ] increase. It was characterised by a narrow signal fluctuation and by a rapid increase (30–40%) in signal intensity. During the second …stage, which was much slower, the signal decreased describing the aggregation process. The EC50 value for ADP-induced spherization was 40 nmol l−1 . Aggregation kinetics in saline solution under turbulent flow showed second order kinetics in relation to initial cell concentration. The rate constant depended on stirring conditions and on calcium concentration in the medium. Standardisation of the testing conditions made it possible to characterize the initial functional state of platelets by their sensitivity to agonists, with estimation of EC50 and maximum velocity of aggregation (Umax  ) values. The method has potential applications in pharmacology and toxicology research and in clinical practice, as a simple and highly sensitive functionality test for platelets. Show more

Keywords: Platelets, aggregation, light scattering, hemostasis, spherization

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 235-246, 2005

Authors: Mindukshev, Igor V. | Ermolaeva, Elena E. | Vivulanets, Elena V. | Shabanova, Elena Yu. | Petrishchev, Nikolay N. | Goncharov, Nikolay V. | Jenkins, Richard O. | Krivchenko, Alexander I.

Article Type: Research Article

Abstract: A new method for studying platelets based on low-angle light scattering has been applied to studies in experimental toxicology and clinical pathology, using animal and human platelets. Index EC50 for ADP within control groups was estimated to be in the range of 100–180 nmol l−1 (healthy men, rabbits, rats). The refractory state of platelets was obtained by use ADP or ATP concentrations that just caused platelet activation. The time constant and the half-cycle of the refractory state of platelets were calculated. Kinetic parameters of platelet aggregation at interference of hemostasis (rabbit) and the influence of the age factors on …the aggregation indices of platelets (rat) were studied. The method of low-angle light scattering was used as a diagnostic tool in experimental low-level intoxication by organophosphates and for interpretation of the pathogenesis of delayed effects. In human patients with ischemic heart disease or with prosthetic heart valves, significant changes in the functional state of platelets were observed. A model for cooperative binding of receptors with ligands on platelets from pregnant women with preeclampsia was developed. Show more

Keywords: Platelets, aggregation, light scattering, preeclampsia, toxicology, pathology

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 247-257, 2005

Authors: Wei, Shaohua | Zhou, Jiahong | Feng, Yuying | Huang, Deyin | Wang, Xuesong | Zhang, Baowen | Shen, Jian

Article Type: Research Article

Abstract: The interaction of anticancer drug hypocrellin B (HB) and mono-cysteine substituted hypocrellin B (MCHB) with calf thymus deoxyribonucleic acid (CT-DNA) has been investigated using spectral methods. The results of UV–visible spectra showed that the HB and MCHB can intercalate into the base-stacking domain of the CT-DNA double helix. Further studies based on fluorescence spectroscopy and circular dichroism (CD) spectroscopy also supported the intercalation mechanism.

Keywords: Hypocrellin B, MCHB, CT-DNA, intercalation mechanism, circular dichroism spectroscopy, fluorescence spectroscopy, anticancer drugs

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 259-266, 2005

Authors: Nosal, W.H. | Thompson, D.W. | Sarkar, S. | Subramanian, A. | Woollam, J.A.

Article Type: Research Article

Abstract: Infrared optical properties of spin-cast chitosan films have been determined using spectroscopic ellipsometry. Infrared index of refraction and extinction coefficients from 750 cm−1 to 4000 cm−1 were determined using ellipsometric data fits to dispersion models based on Gaussian shaped oscillators. The free electron contribution was analyzed using a Drude model. This modeling determined that optical anisotropy was present over the entire infrared region. Line shape and oscillator strength analysis was performed to determine oscillator strengths, abundance, and relative bond strength.

Keywords: Bond occurrence, chitosan, ellipsometry, infrared spectrum, oscillator strength

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 267-274, 2005

Authors: Isab, Anvarhusein A. | Wazeer, Mohamed I.M.

Article Type: Research Article

Abstract: Complexation of Ag+ as AgNO3 , solid AgCN and Ag(CN)2 − by labeled and unlabeled L-methionine, DL-selenomethionine and d,l-thiomalate were studied by nuclear magnetic resonance methods. The 13 C NMR indicates that only Ag+ react with the both L-methionine, DL-selenomethionine at neutral and higher pH via CO2 − and S or Se atom forming a chelate. The Ag(CN)2 − and AgCN do not bind to either of these two ligands at any pH. The Ag13 CN, which is an insoluble polymer, can react with thiomalate to form chelate complexes at neutral pH. Various structures for …the chelate formations are proposed. Show more

Keywords: L-methionine, DL-selenomethionine, d,l-thiomalate, AgNO$_{3}$, AgCN and Ag(CN)$_{2}^{-}$, $^{13}$C NMR

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 275-281, 2005

Authors: Jankowski, Christopher K. | BouLaouz, Antoun | Diaz-Torres, Eduardo

Article Type: Research Article

Abstract: Some additional evidences on the mechanism of new rearrangment of dihalocyclopropane–dihalomethylvinyl reaction assisted by Hiyama reagent Cr+2 /Cr+3 are discussed.

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 283-286, 2005

Article Type: Other

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 287-290, 2005

Article Type: Other

Citation: Spectroscopy, vol. 19, no. 5-6, pp. 291-291, 2005