A challenge that must be addressed when conducting studies with complex natural products is how t... more A challenge that must be addressed when conducting studies with complex natural products is how to evaluate their complexity and variability. Traditional methods of quantifying a single or a small range of metabolites may not capture the full chemical complexity of multiple samples. Different metabolomics approaches were evaluated to discern how they facilitated comparison of the chemical composition of commercial green tea [Camellia sinensis (L.) Kuntze] products, with the goal of capturing the variability of commercially used products and selecting representative products for in vitro or clinical evaluation. Three metabolomic-related methodsuntar-geted ultraperformance liquid chromatography−mass spectrom-etry (UPLC-MS), targeted UPLC-MS, and untargeted, quantitative 1 HNMRwere employed to characterize 34 commercially available green tea samples. Of these methods, untargeted UPLC-MS was most effective at discriminating between green tea, green tea supplement, and non-green-tea products. A method using reproduced correlation coefficients calculated from principal component analysis models was developed to quantitatively compare differences among samples. The obtained results demonstrated the utility of metabolomics employing UPLC-MS data for evaluating similarities and differences between complex botanical products.
To investigate the effect of a seven-month, school-based cluster-randomized controlled trial on a... more To investigate the effect of a seven-month, school-based cluster-randomized controlled trial on academic performance in 10-year-old children. In total, 1129 fifth-grade children from 57 elementary schools in Sogn og Fjordane County, Norway, were cluster-randomized by school either to the intervention group or to the control group. The children in the 28 intervention schools participated in a physical activity intervention between November 2014 and June 2015 consisting of three components: 1) 90min/week of physically active educational lessons mainly carried out in the school playground; 2) 5min/day of physical activity breaks during classroom lessons; 3) 10min/day physical activity homework. Academic performance in numeracy, reading and English was measured using standardized Norwegian national tests. Physical activity was measured objectively by accelerometry. We found no effect of the intervention on academic performance in primary analyses (standardized difference 0.01-0.06, p>...
Cerebrospinal fluid (CSF) is a perfect source to search for new biomarkers to improve early diagn... more Cerebrospinal fluid (CSF) is a perfect source to search for new biomarkers to improve early diagnosis of neurological diseases. Standardization of pre-analytical handling of the sample is, however, important to obtain acceptable analytical quality. In the present study, MALDI-TOF MS was used to examine the influence of pre-analytical sample procedures on the low molecular weight (MW) CSF proteome. Different storage conditions like temperature and duration or the addition of as little as 0.2 mL blood/mL neat CSF caused significant changes in the mass spectra. The performance of different types of MW cut-off spin cartridges from different suppliers used to enrich the low MW CSF proteome showed great variance in cut-off accuracy, stability and reproducibility. The described analytical method achieved a polypeptide discriminating limit of approximately 800 pM, two to three orders of magnitude lower than reported for plasma. Based on this study, we recommend that CSF is centrifuged immediately after sampling, prior to storage at -807C without addition of protease inhibitors. Guanidinium hydrochloride is preferred to break protein-protein interactions. A spin cartridge with cut-off limit above the intended analytical mass range is recommended. Our study contributes to the important task of developing standardized pre-analytical protocols for the proteomic study of CSF.
ABSTRACT Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesize... more ABSTRACT Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesized from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted with lauroyl chloride by using the Friedel-Crafts reaction. The conversion of vinyl groups was followed by analyzing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy in both the mid- and near-infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the reaction. Spectra of the particles in the mid-IR region provide understanding of the changes taking place in the polymer matrix during the acylation reaction. The results indicated that the reaction took place at a faster rate in the polymer particles synthesized from para-DVB monomer compared with the poly(meta-DVB) particles. The polymer particles synthesized with toluene as porogen react faster than the polymer particles prepared with 2-ethylhexanoic acid as the porogen. The analysis also indicated that the acylation takes place at the early stages of the reaction and the product formed transforms into more stable products at the latter stages. On the basis of the infrared analysis, mechanisms for the formation of the different products are proposed.
Karstang, T.V. and KvaIheim, O.M., 1991. Comparison between three techniques for background corre... more Karstang, T.V. and KvaIheim, O.M., 1991. Comparison between three techniques for background correction in quantitative analysis. Chemometrics and Intelligent L&oratory Systems, 12: 147-154. The three background techniques compared in this work ah take as their starting point a principal component (PC) model that describes the calibration space. The PC model is then combined with a function that describes the spectrum of the background constituents. Three data sets are analyzed, of which two are normalized to constant sum for the concentrations. The results using (1) curve fitting (CF), (2) iterative target transformation factor anaIysis, and (3) local curve fitting (LCF), indicate that the curve fitting techniques (LCF and CF) give smallest prediction errors. 0169-7439/91/$03.50 0 1991 -EIsevier Science Publishers B.V. AII rights reserved
For efficient handling of very large data arrays, pretreatment by compression is mandatory. In th... more For efficient handling of very large data arrays, pretreatment by compression is mandatory. In the present paper B-spline methods are described as good candidates for such data array compression. The mathematical relation between the maximum entropy method for compression of data tables and the B-spline of zeroth degree is described together with the generalization of B-spline compression to nth-order data array tables in matrix and tensor algebra.
... rank analysis of the first-order differentiated elution profile in the time domain Yi-Zeng Li... more ... rank analysis of the first-order differentiated elution profile in the time domain Yi-Zeng Liang 1, Rolf Manne, Olav M. Kvalheim * Department of ... this work is to develop a technique that is able to locate the chromatographic (or equivalently, spectral) maxima of the pure ana-lytes in ...
Physical activity and high aerobic fitness protects against cardiovascular disease and early deat... more Physical activity and high aerobic fitness protects against cardiovascular disease and early death, besides having a very modest impact on lipoprotein-cholesterol in obese subjects. Physical activity has been shown to favourably alter lipoprotein particle concentrations and apolipoprotein B with minimal weight loss in overweight to moderately obese subjects. We studied the impact of physical activity on lipoprotein subclass particle concentrations in women with severe obesity. Increased physical activity duration was associated with favourable changes, whereas increased PA intensity was associated with adverse changes in some lipoprotein particle subclasses in severely obese women. Severely obese women that manage to increase their physical activity level can improve their lipoprotein profile, whether or not they lose fat mass Physical activity (PA) and high aerobic fitness protects against cardiovascular disease and early death possibly among others because of an anti-atherogenic i...
... Infrared microspectrometry has established its effectiveness and usefulness in ana-lysing mic... more ... Infrared microspectrometry has established its effectiveness and usefulness in ana-lysing micro samples. ... development of different chemometric tech-niques for different applications in chemistry (Kvalhejm and Liang, 1992; Liang et al., 1992; Toft and Kvalheim, 1993; Liang and ...
Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from pa... more Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted using aluminium chloride with dichlorobenzene as a catalyst. The conversion of vinyl groups was followed by analysing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy both in the mid and near infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the vinyl group consumption. Infrared spectra of the particles in the mid IR were also measured to understand changes taking place in the polymer matrix during the reaction. The results indicated that residual vinyl groups in these polymer particles were consumed during the reaction with aluminium ch...
Curve resolution of infrared profiles from non-conformational mixtures and conformational equilib... more Curve resolution of infrared profiles from non-conformational mixtures and conformational equilibria is discussed. For successful resolution it is crucial that temperature and solvent induced variations observed as peak shifts and band broadening are accounted for. As changes in absorbance (in IR) or intensities (in Raman) with temperature may be different for different bands of the same conformer, the resolution must be performed on local parts of the spectra. An assumption about temperature independence of the integrated extinction coefficients in such a local region of the spectra must be made. The success of curve resolution by compensating for thermal effects is largely determined by the level of the experimental noise, the change in analyte concentrations with temperature and the thermal effects. Curve resolution of mixture spectra is illustrated using model spectra of toluene and cyclohexane and variable temperature spectra of chlorocyclohexane.
A challenge that must be addressed when conducting studies with complex natural products is how t... more A challenge that must be addressed when conducting studies with complex natural products is how to evaluate their complexity and variability. Traditional methods of quantifying a single or a small range of metabolites may not capture the full chemical complexity of multiple samples. Different metabolomics approaches were evaluated to discern how they facilitated comparison of the chemical composition of commercial green tea [Camellia sinensis (L.) Kuntze] products, with the goal of capturing the variability of commercially used products and selecting representative products for in vitro or clinical evaluation. Three metabolomic-related methodsuntar-geted ultraperformance liquid chromatography−mass spectrom-etry (UPLC-MS), targeted UPLC-MS, and untargeted, quantitative 1 HNMRwere employed to characterize 34 commercially available green tea samples. Of these methods, untargeted UPLC-MS was most effective at discriminating between green tea, green tea supplement, and non-green-tea products. A method using reproduced correlation coefficients calculated from principal component analysis models was developed to quantitatively compare differences among samples. The obtained results demonstrated the utility of metabolomics employing UPLC-MS data for evaluating similarities and differences between complex botanical products.
To investigate the effect of a seven-month, school-based cluster-randomized controlled trial on a... more To investigate the effect of a seven-month, school-based cluster-randomized controlled trial on academic performance in 10-year-old children. In total, 1129 fifth-grade children from 57 elementary schools in Sogn og Fjordane County, Norway, were cluster-randomized by school either to the intervention group or to the control group. The children in the 28 intervention schools participated in a physical activity intervention between November 2014 and June 2015 consisting of three components: 1) 90min/week of physically active educational lessons mainly carried out in the school playground; 2) 5min/day of physical activity breaks during classroom lessons; 3) 10min/day physical activity homework. Academic performance in numeracy, reading and English was measured using standardized Norwegian national tests. Physical activity was measured objectively by accelerometry. We found no effect of the intervention on academic performance in primary analyses (standardized difference 0.01-0.06, p>...
Cerebrospinal fluid (CSF) is a perfect source to search for new biomarkers to improve early diagn... more Cerebrospinal fluid (CSF) is a perfect source to search for new biomarkers to improve early diagnosis of neurological diseases. Standardization of pre-analytical handling of the sample is, however, important to obtain acceptable analytical quality. In the present study, MALDI-TOF MS was used to examine the influence of pre-analytical sample procedures on the low molecular weight (MW) CSF proteome. Different storage conditions like temperature and duration or the addition of as little as 0.2 mL blood/mL neat CSF caused significant changes in the mass spectra. The performance of different types of MW cut-off spin cartridges from different suppliers used to enrich the low MW CSF proteome showed great variance in cut-off accuracy, stability and reproducibility. The described analytical method achieved a polypeptide discriminating limit of approximately 800 pM, two to three orders of magnitude lower than reported for plasma. Based on this study, we recommend that CSF is centrifuged immediately after sampling, prior to storage at -807C without addition of protease inhibitors. Guanidinium hydrochloride is preferred to break protein-protein interactions. A spin cartridge with cut-off limit above the intended analytical mass range is recommended. Our study contributes to the important task of developing standardized pre-analytical protocols for the proteomic study of CSF.
ABSTRACT Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesize... more ABSTRACT Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesized from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted with lauroyl chloride by using the Friedel-Crafts reaction. The conversion of vinyl groups was followed by analyzing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy in both the mid- and near-infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the reaction. Spectra of the particles in the mid-IR region provide understanding of the changes taking place in the polymer matrix during the acylation reaction. The results indicated that the reaction took place at a faster rate in the polymer particles synthesized from para-DVB monomer compared with the poly(meta-DVB) particles. The polymer particles synthesized with toluene as porogen react faster than the polymer particles prepared with 2-ethylhexanoic acid as the porogen. The analysis also indicated that the acylation takes place at the early stages of the reaction and the product formed transforms into more stable products at the latter stages. On the basis of the infrared analysis, mechanisms for the formation of the different products are proposed.
Karstang, T.V. and KvaIheim, O.M., 1991. Comparison between three techniques for background corre... more Karstang, T.V. and KvaIheim, O.M., 1991. Comparison between three techniques for background correction in quantitative analysis. Chemometrics and Intelligent L&oratory Systems, 12: 147-154. The three background techniques compared in this work ah take as their starting point a principal component (PC) model that describes the calibration space. The PC model is then combined with a function that describes the spectrum of the background constituents. Three data sets are analyzed, of which two are normalized to constant sum for the concentrations. The results using (1) curve fitting (CF), (2) iterative target transformation factor anaIysis, and (3) local curve fitting (LCF), indicate that the curve fitting techniques (LCF and CF) give smallest prediction errors. 0169-7439/91/$03.50 0 1991 -EIsevier Science Publishers B.V. AII rights reserved
For efficient handling of very large data arrays, pretreatment by compression is mandatory. In th... more For efficient handling of very large data arrays, pretreatment by compression is mandatory. In the present paper B-spline methods are described as good candidates for such data array compression. The mathematical relation between the maximum entropy method for compression of data tables and the B-spline of zeroth degree is described together with the generalization of B-spline compression to nth-order data array tables in matrix and tensor algebra.
... rank analysis of the first-order differentiated elution profile in the time domain Yi-Zeng Li... more ... rank analysis of the first-order differentiated elution profile in the time domain Yi-Zeng Liang 1, Rolf Manne, Olav M. Kvalheim * Department of ... this work is to develop a technique that is able to locate the chromatographic (or equivalently, spectral) maxima of the pure ana-lytes in ...
Physical activity and high aerobic fitness protects against cardiovascular disease and early deat... more Physical activity and high aerobic fitness protects against cardiovascular disease and early death, besides having a very modest impact on lipoprotein-cholesterol in obese subjects. Physical activity has been shown to favourably alter lipoprotein particle concentrations and apolipoprotein B with minimal weight loss in overweight to moderately obese subjects. We studied the impact of physical activity on lipoprotein subclass particle concentrations in women with severe obesity. Increased physical activity duration was associated with favourable changes, whereas increased PA intensity was associated with adverse changes in some lipoprotein particle subclasses in severely obese women. Severely obese women that manage to increase their physical activity level can improve their lipoprotein profile, whether or not they lose fat mass Physical activity (PA) and high aerobic fitness protects against cardiovascular disease and early death possibly among others because of an anti-atherogenic i...
... Infrared microspectrometry has established its effectiveness and usefulness in ana-lysing mic... more ... Infrared microspectrometry has established its effectiveness and usefulness in ana-lysing micro samples. ... development of different chemometric tech-niques for different applications in chemistry (Kvalhejm and Liang, 1992; Liang et al., 1992; Toft and Kvalheim, 1993; Liang and ...
Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from pa... more Porous poly(para-divinylbenzene) and poly(meta-divinylbenzene) particles were synthesised from para-divinylbenzene and meta-divinylbenzene monomers with toluene and 2-ethylhexanoic acid as porogens. The residual vinyl groups in the particles were thereafter reacted using aluminium chloride with dichlorobenzene as a catalyst. The conversion of vinyl groups was followed by analysing polymer particles taken from the reaction mixture at different time intervals. Infrared spectroscopy both in the mid and near infrared region was used as the analytical technique. The intensity changes in the overtone absorption at 1628 nm due to the vinyl bonds were used as the basis for the quantification of the vinyl group consumption. Infrared spectra of the particles in the mid IR were also measured to understand changes taking place in the polymer matrix during the reaction. The results indicated that residual vinyl groups in these polymer particles were consumed during the reaction with aluminium ch...
Curve resolution of infrared profiles from non-conformational mixtures and conformational equilib... more Curve resolution of infrared profiles from non-conformational mixtures and conformational equilibria is discussed. For successful resolution it is crucial that temperature and solvent induced variations observed as peak shifts and band broadening are accounted for. As changes in absorbance (in IR) or intensities (in Raman) with temperature may be different for different bands of the same conformer, the resolution must be performed on local parts of the spectra. An assumption about temperature independence of the integrated extinction coefficients in such a local region of the spectra must be made. The success of curve resolution by compensating for thermal effects is largely determined by the level of the experimental noise, the change in analyte concentrations with temperature and the thermal effects. Curve resolution of mixture spectra is illustrated using model spectra of toluene and cyclohexane and variable temperature spectra of chlorocyclohexane.
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Papers by Olav Kvalheim