Browsing by Subject "kinetics"

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  • Rautaniemi, Kaisa; Vuorimaa-Laukkanen, Elina; Strachan, Clare J.; Laaksonen, Timo (2018)
    Pharmaceutical scientists are increasingly interested in amorphous drug formulations especially because of their higher dissolution rates. Consequently, the thorough characterization and analysis of these formulations are becoming more and more important for the pharmaceutical industry. Here, fluorescence lifetime-imaging microscopy (FLIM) was used to monitor the crystallization of an amorphous pharmaceutical compound, indomethacin. Initially, we identified different solid indomethacin forms, amorphous and gamma- and alpha-crystalline, on the basis of their time-resolved fluorescence. All of the studied indomethacin forms showed biexponential decays with characteristic fluorescence lifetimes and amplitudes. Using this information, the crystallization of amorphous indomethacin upon storage in 60 degrees C was monitored for 10 days with FLIM. The progress of crystallization was detected as lifetime changes both in the FLIM images and in the fluorescence-decay curves extracted from the images. The fluorescence-lifetime amplitudes were used for quantitative analysis of the crystallization process. We also demonstrated that the fluorescence-lifetime distribution of the sample changed during crystallization, and when the sample was not moved between measuring times, the lifetime distribution could also be used for the analysis of the reaction kinetics. Our results clearly show that FLIM is a sensitive and nondestructive method for monitoring solid-state transformations on the surfaces of fluorescent samples.
  • European Soc Blood Marrow Transpla; HOVON-SAKK (2018)
    Background. Disease recurrence remains the major cause of death in adults with acute myeloid leukaemia (AML) treated using either intensive chemotherapy (IC) or allogenic stem cell transplantation (allo-SCT). Aims. The timely delivery of maintenance drug or cellular therapies represent emerging strategies with the potential to reduce relapse after both treatment modalities, but whilst the determinants of overall relapse risk have been extensively characterized the factors determining the timing of disease recurrence have not been characterized. Materials and Methods. We have therefore examined, using a series of sequential landmark analyses, relapse kinetics in a cohort of 2028 patients who received an allo-SCT for AML in CR1 and separately 570 patients treated with IC alone. Results. In the first 3 months after allo-SCT, the factors associated with an increased risk of relapse included the presence of the FLT3-ITD (P <0.001), patient age (P = 0.012), time interval from CR1 to transplant (P <0.001) and donor type (P = 0.03). Relapse from 3 to 6 months was associated with a higher white cell count at diagnosis (P = 0.001), adverse-risk cytogenetics (P <0.001), presence of FLT3-ITD mutation (P <0.001) and time interval to achieve first complete remission (P = 0.013). Later relapse was associated with adverse cytogenetics, mutated NPM1, absence of chronic graft-versus-host disease (GVHD) and the use of in vivo T-cell depletion. In patients treated with IC alone, the factors associated with relapse in the first 3 months were adverse-risk cytogenetics (P <0.001) and FLT3-ITD status (P = 0.001). The factors predicting later relapse were the time interval from diagnosis to CR1 (P = 0.22) and time interval from CR1 to IC (P = 0.012). Discussion and Conclusion. Taken together, these data provide novel insights into the biology of disease recurrence after both allo-SCT and IC and have the potential to inform the design of novel maintenance strategies in both clinical settings.
  • Multia, Evgen (Helsingfors universitet, 2017)
    The literature part of this thesis reviewed the process of obtaining affinity information with quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) biosensors. Basic principles of these biosensors were also evaluated, along with the principles of data acquisition and finally the data processing. The raw data produced by QCM or SPR can be used to study biomolecular interactions qualitatively and quantitatively. These techniques are also powerful in obtaining kinetic and thermodynamic information of the biomolecular interactions. SPR and QCM can produce data easily, but data interpretation can be sometimes problematic. This is partly due to misconceptions on how the sensograms should be interpreted. Many of the interpretational problems can and should be avoided long before the modeling of the data takes place to obtain reliable affinity data. The literature part of this thesis also presents tools for developing good experimental design. Well-designed experimental set-up is the most important element for producing good biosensor data. One should also estimate from the sensogram shapes what kind of analysis is needed. This was explained in detail in the literature part, pointing out the key elements how sensograms with certain shape should be interpreted and further analyzed to obtain affinity constants. Data analysis part of the literature review provides also information how to use appropriate models (e.g. fitting equilibrium, kinetic or complex data) with extensive examples. Surface site distribution model will be also covered as the tool to analyze complex biomolecular interactions by QCM and SPR. In the experimental part, affinity of anti-human apoB-100 monoclonal antibody (anti-apoB-100 Mab) towards different lipoproteins was studied with partially filling affinity capillary (PF-ACE) electrophoresis and QCM. PF-ACE with adsorption energy distribution (AED) calculations provided information on the heterogeneity of the interactions. For the first time, a modified surface site distribution model called Interaction map was utilized to model QCM data of lipoprotein interactions with anti-apoB-100 Mab. With the Interaction maps, it was possible to distinguish different kinetics of low-density lipoprotein (LDL) and anti-apoB-100 Mab interactions. Affinity constants obtained were used to evaluate thermodynamics of these interactions. Both methods were also used to evaluate interactions with other apoB-100 containing lipoproteins: intermediate-density lipoprotein (IDL) and very lowdensity lipoprotein (VLDL). It was found that the Interaction maps could distinguish two different kinetics from the mixture of IDL-VLDL with distinct affinity constants. Both methods agreed well with the affinity constants. It was found that the anti-apoB-100 Mab used in this study, had a high affinity towards apoB-100 containing lipoproteins. In the second part of the experimental, a convective interaction media (CIM) based LDL isolation platform was developed. In these studies, anti-apoB-100 Mab was immobilized on the CIM-disk and was used to isolate LDL from human plasma and serum samples. It was found that apolipoprotein based separation of LDL from plasma was possible, although not without difficulties, since apoB-100 is not only present in LDL, but also in VLDL and IDL. To circumvent this problem different antibodies (anti-apoE and anti-apoAI) were utilized to capture VLDL and IDL from the plasma before the interaction of LDL with the anti-apoB-100 CIM-disk. LDL was successfully isolated with this approach in a significantly reduced time compared to conventional ultracentrifugation method used for LDL isolation.
  • Björnson, E.; Packard, C. J.; Adiels, M.; Andersson, L.; Matikainen, Niina; Söderlund, S.; Kahri, J.; Sihlbom, C.; Thorsell, A.; Zhou, H.; Taskinen, M.-R.; Borén, J. (2019)
    Background Triglyceride-rich lipoproteins and their remnants have emerged as major risk factors for cardiovascular disease. New experimental approaches are required that permit simultaneous investigation of the dynamics of chylomicrons (CM) and apoB48 metabolism and of apoB100 in very low-density lipoproteins (VLDL). Methods Mass spectrometric techniques were used to determine the masses and tracer enrichments of apoB48 in the CM, VLDL1 and VLDL2 density intervals. An integrated non-steady-state multicompartmental model was constructed to describe the metabolism of apoB48- and apoB100-containing lipoproteins following a fat-rich meal, as well as during prolonged fasting. Results The kinetic model described the metabolism of apoB48 in CM, VLDL1 and VLDL2. It predicted a low level of basal apoB48 secretion and, during fat absorption, an increment in apoB48 release into not only CM but also directly into VLDL1 and VLDL2. ApoB48 particles with a long residence time were present in VLDL, and in subjects with high plasma triglycerides, these lipoproteins contributed to apoB48 measured during fasting conditions. Basal apoB48 secretion was about 50 mg day?1, and the increment during absorption was about 230 mg day?1. The fractional catabolic rates for apoB48 in VLDL1 and VLDL2 were substantially lower than for apoB48 in CM. Discussion This novel non-steady-state model integrates the metabolic properties of both apoB100 and apoB48 and the kinetics of triglyceride. The model is physiologically relevant and provides insight not only into apoB48 release in the basal and postabsorptive states but also into the contribution of the intestine to VLDL pool size and kinetics.
  • Adiels, Martin; Mardinoglu, Adil; Taskinen, Marja-Riitta; Boren, Jan (2015)
    To develop novel strategies for prevention and treatment of dyslipidemia, it is essential to understand the pathophysiology of dyslipoproteinemia in humans. Lipoprotein metabolism is a complex system in which abnormal concentrations of various lipoprotein particles can result from alterations in their rates of production, conversion, and/or catabolism. Traditional methods that measure plasma lipoprotein concentrations only provide static estimates of lipoprotein metabolism and hence limited mechanistic information. By contrast, the use of tracers labeled with stable isotopes and mathematical modeling, provides us with a powerful tool for probing lipid and lipoprotein kinetics in vivo and furthering our understanding of the pathogenesis of dyslipoproteinemia.
  • Rico del Cerro, Daniel; Mera-Adasme, Raúl; King, Alistair W. T.; Perea-Buceta, Jesus E.; Heikkinen, Sami; Hase, Tapio; Sundholm, Dage; Wähälä, Kristiina (2018)
    Comprehensive spectroscopic kinetic studies illustrate an alternative mechanism for the traditional free-carbene intermediated H/D exchange reaction of 1,3-dialkylimidazolium salts under neutral (D2O) and acidic conditions (DCl/D2O 35wt% solution). The deuteration of high purity [bmim]Cl in D2O is studied at different temperatures, in absence of catalyst or impurities, to yield an activation energy. DFT transition-state modelling, of a small water cluster and [bmim] cation, also yields an activation energy which strongly supports the proposed mechanism. The presence of basic impurities are shown to significantly enhance the exchange reaction, which brings into question the need for further analysis of technical purities of ionic liquids and the implications for a wide range of chemical reactions in such media.
  • Scaramuzzo, Gaetano; Broche, Ludovic; Pellegrini, Mariangela; Porra, Liisa; Derosa, Savino; Tannoia, Angela Principia; Marzullo, Andrea; Borges, Joao Batista; Bayat, Sam; Bravin, Alberto; Larsson, Anders; Perchiazzi, Gaetano (2019)
    Introduction: The mechanisms of lung inflation and deflation are only partially known. Ventilatory strategies to support lung function rely upon the idea that lung alveoli are isotropic balloons that progressively inflate or deflate and that lung pressure/volume curves derive only by the interplay of critical opening pressures, critical closing pressures, lung history, and position of alveoli inside the lung. This notion has been recently challenged by subpleural microscopy, magnetic resonance, and computed tomography (CT). Phase-contrast synchrotron radiation CT (PC-SRCT) can yield in vivo images at resolutions higher than conventional CT. Objectives: We aimed to assess the numerosity (ASden) and the extension of the surface of airspaces (ASext) in healthy conditions at different volumes, during stepwise lung deflation, in concentric regions of the lung. Methods: The study was conducted in seven anesthetized New Zealand rabbits. They underwent PC-SRCT scans (resolution of 47.7 mu m) of the lung at five decreasing positive end expiratory pressure (PEEP) levels of 12, 9, 6, 3, and 0 cmH(2)O during end-expiratory holds. Three concentric regions of interest (ROIs) of the lung were studied: subpleural, mantellar, and core. The images were enhanced by phase contrast algorithms. ASden and ASext were computed by using the Image Processing Toolbox for MatLab. Statistical tests were used to assess any significant difference determined by PEEP or ROI on ASden and ASext. Results: When reducing PEEP, in each ROI the ASden significantly decreased. Conversely, ASext variation was not significant except for the core ROI. In the latter, the angular coefficient of the regression line was significantly low. Conclusion: The main mechanism behind the decrease in lung volume at PEEP reduction is derecruitment. In our study involving lung regions laying on isogravitational planes and thus equally influenced by gravitational forces, airspace numerosity and extension of surface depend on the local mechanical properties of the lung.
  • Hyytiäinen, Heli K.; Blomvall, Laura; Hautala, Mikko; Lappalainen, Anu K. (2021)
    Simple Summary Information on the biomechanics of police dogs' tasks is important in preventing, diagnosing and treating their work-related injuries and dysfunctions. Despite the fact that dogs in several fields of service are performing protective tasks, there is lack of information regarding the occupational physical demands these dogs are subjected to. This study aimed to develop and test a measurement sleeve for measuring dogs' functional bite force, and to report locomotion-related values during a modified long attack. The measurement sleeve was found to be reliable, although individual tooth force could not be reported, as the forces were above the scale of our sensors. The dogs' jaws pressing force, on the other hand, was not high, whereas during acceleration and deceleration the dogs were subjected to relatively high gravitational force equivalents. There are differences between two breeds of police dogs' locomotion during the modified long attack task. The results gained from this study provide information which can be used to benefit the working dogs' welfare during their use and training, as more in-depth understanding of the strains to their neuromusculoskeletal system is available. Information on the biomechanics of police dogs' tasks is important in understanding their work-related injuries and dysfunctions. This study aimed to develop and test a measurement tool for dogs' functional bite force and to report modified long attack-related kinetic and kinematic values. Twenty Finnish male police dogs, 7 German Shepherd Dogs (GSDs) and 13 Belgian Shepherd Dogs, Malinois (BSDMs), were included. Dogs accelerated 25 m and bit the helper's sleeve, fitted with three force sensors. Dogs were wearing a 3D accelerometer and were videotaped with a high-speed camera. The sleeve's reliability for measuring the dog's bite force was evaluated via intraclass correlation and Cronbach's alpha. Otherwise, a Mann-Whitney U-test was used, with significance set at p = 0.05. The sleeve's test-retest reliability was moderate to good (intraclass correlation of 0.75), and internal consistency was high (Cronbach's alpha 0.75). The GSDs' median bite force was 360.4 N (interquartile range (IQR) 628.6 N) and BSDMs' 247.0 N (IQR 289.8 N). Median acceleration maximum was 7.1 gravitational force equivalent (g) and median deceleration maximum was 11.6 g, with highest recorded forces being 9.2 g and 13.1 g, respectively. The measurement sleeve was a reliable tool for measuring functional bite force in GSDs and BSDMs. Forces related to bite, approach and impact in the two breeds were reported.
  • Adiels, Martin; Taskinen, Marja-Riitta; Björnson, Elias; Andersson, Linda; Matikainen, Niina; Söderlund, Sanni; Kahri, Juhani; Hakkarainen, Antti; Lundbom, Nina; Sihlbom, Carina; Thorsell, Annika; Zhou, Haihong; Pietiläinen, Kirsi H.; Packard, Chris; Boren, Jan (2019)
    Aims To investigate how apolipoprotein C-III (apoC-III) metabolism is altered in subjects with type 2 diabetes, whether the perturbed plasma triglyceride concentrations in this condition are determined primarily by the secretion rate or the removal rate of apoC-III, and whether improvement of glycaemic control using the glucagon-like peptide-1 analogue liraglutide for 16 weeks modifies apoC-III dynamics. Materials and Methods Postprandial apoC-III kinetics were assessed after a bolus injection of [5,5,5-H-2(3)]leucine using ultrasensitive mass spectrometry techniques. We compared apoC-III kinetics in two situations: in subjects with type 2 diabetes before and after liraglutide therapy, and in type 2 diabetic subjects with matched body mass index (BMI) non-diabetic subjects. Liver fat content, subcutaneous abdominal and intra-abdominal fat were determined using proton magnetic resonance spectroscopy. Results Improved glycaemic control by liraglutide therapy for 16 weeks significantly reduced apoC-III secretion rate (561 +/- 198 vs. 652 +/- 196 mg/d, P = 0.03) and apoC-III levels (10.0 +/- 3.8 vs. 11.7 +/- 4.3 mg/dL, P = 0.035) in subjects with type 2 diabetes. Change in apoC-III secretion rate was significantly associated with the improvement in indices of glucose control (r = 0.67; P = 0.009) and change in triglyceride area under the curve (r = 0.59; P = 0.025). In line with this, the apoC-III secretion rate was higher in subjects with type 2 diabetes compared with BMI-matched non-diabetic subjects (676 +/- 208 vs. 505 +/- 174 mg/d, P = 0.042). Conclusions The results reveal that the secretion rate of apoC-III is associated with elevation of triglyceride-rich lipoproteins in subjects with type 2 diabetes, potentially through the influence of glucose homeostasis on the production of apoC-III.
  • Scaramuzzo, Gaetano; Broche, Ludovic; Pellegrini, Mariangela; Porra, Liisa; Derosa, Savino; Tannoia, Angela Principia; Marzullo, Andrea; Borges, Joao Batista; Bayat, Sam; Bravin, Alberto; Larsson, Anders; Perchiazzi, Gaetano (2019)
    Modern ventilatory strategies are based on the assumption that lung terminal airspaces act as isotropic balloons that progressively accommodate gas. Phase contrast synchrotron radiation computed tomography (PCSRCT) has recently challenged this concept, showing that in healthy lungs, deflation mechanisms are based on the sequential de-recruitment of airspaces. Using PCSRCT scans in an animal model of acute respiratory distress syndrome (ARDS), this study examined whether the numerosity (ASnum) and dimension (ASdim) of lung airspaces change during a deflation maneuver at decreasing levels of positive end-expiratory pressure (PEEP) at 12, 9, 6, 3, and 0 cmH(2)O. Deflation was associated with significant reduction of ASdim both in the whole lung section (passing from from 13.1 +/- 2.0 at PEEP 12 to 7.6 +/- 4.2 voxels at PEEP 0) and in single concentric regions of interest (ROIs). However, the regression between applied PEEP and ASnum was significant in the whole slice (ranging from 188 +/- 52 at PEEP 12 to 146.4 +/- 96.7 at PEEP 0) but not in the single ROIs. This mechanism of deflation in which reduction of ASdim is predominant, differs from the one observed in healthy conditions, suggesting that the peculiar alveolar micromechanics of ARDS might play a role in the deflation process.
  • Eskola, Arrke J.; Blitz, Mark A.; Pilling, Michael J.; Seakins, Paul W.; Shannon, Robin J. (2020)
    The rate coefficient for the unimolecular decomposition of CH3OCH2,k(1), has been measured in time-resolved experiments by monitoring the HCHO product. CH3OCH2 was rapidly and cleanly generated by 248 nm excimer photolysis of oxalyl chloride, (ClCO)(2), in an excess of CH3OCH3, and an excimer pumped dye laser tuned to 353.16 nm was used to probe HCHO via laser induced fluorescence. k(1)(T,p) was measured over the ranges: 573-673 K and 0.1-4.3 x 10(18) molecule cm(-3) with a helium bath gas. In addition, some experiments were carried out with nitrogen as the bath gas. Ab initio calculations on CH3OCH2 decomposition were carried out and a transition-state for decomposition to CH3 and H2CO was identified. This information was used in a master equation rate calculation, using the MESMER code, where the zero-point-energy corrected barrier to reaction, Delta E-0,E-1, and the energy transfer parameters, x T-n, were the adjusted parameters to best fit the experimental data, with helium as the buffer gas. The data were combined with earlier measurements by Loucks and Laidler (Can J. Chem. 1967, 45, 2767), with dimethyl ether as the third body, reinterpreted using current literature for the rate coefficient for recombination of CH3OCH2. This analysis returned Delta E-0,E-1 = (112.3 +/- 0.6) kJ mol(-1), and leads to k(1)(infinity)(T) = 2.9 x 10(12) (T/300)(2)(.5) exp(-106.8 kJ mol(-1)/RT). Using this model, limited experiments with nitrogen as the bath gas allowed N-2 energy transfer parameters to be identified and then further MESMER simulations were carried out, where N-2 was the buffer gas, to generate k(1)(T,p) over a wide range of conditions: 300-1000 K and N-2 = 10(12) -10(25) molecule cm(-3). The resulting k(1)(T,p) has been parameterized using a Troe-expression, so that they can be readily be incorporated into combustion models. In addition, k(1)(T,p) has been parametrized using PLOG for the buffer gases, He, CH3OCH3 and N-2.