143 results on '"Carlsson, N."'
Search Results
102. Characterization of two-dimensional AlGaAs photonic crystals with waveguides as a test device.
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Kawai, N., Inoue, K., Sasada, M., Ikeda, N., Carlsson, N., Abe, S., Asakawa, K., Yamada, S., and Katayama, Y.
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- 2000
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103. Manipulations of densities and sizes during self-assembling quantum dots in MOVPE.
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Seifert, W., Johansson, J., and Carlsson, N.
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- 1999
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104. Two-dimensional AlGaAs photonic crystal air-bridge structure with defect waveguides for miniaturized planar light-wave circuit.
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Ikeda, N., Sugimoto, Y., Carlsson, N., and Asakawa, K.
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- 2001
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105. Leak loss analysis of slab-type waveguides consisting of two-dimensional photonic crystal.
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Abe, S., Carlsson, N., and Asakawa, K.
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- 2000
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106. Large enhancement of optical nonlinearity using quantum dots embedded in a photonic crystal structure for all-optical switch applications.
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Nakamura, H., Kohmoto, S., Carlsson, N., Sugimoto, Y., and Asakawa, K.
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- 2000
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107. Characteristics of two-dimensional AlGaAs photonic crystals in a waveguide configuration for test devices.
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Inoue, K., Kawai, N., Sasada, M., Ikeda, N., Carlsson, N., Asakawa, K., Abe, S., Yamada, S., and Katayama, Y.
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- 1999
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108. Conductance oscillations induced by longitudinal resonant states in heteroepitaxially defined Ga[sub 0.25]In[sub 0.75]As/InP electron waveguides.
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Wang, Qin, Qin Wang, Carlsson, N., Maximov, I., Omling, P., Samuelson, L., Seifert, W., Sheng, Weidong, Weidong Sheng, Shorubalko, I., Xu, H. Q., and Xu, H.Q.
- Subjects
WAVEGUIDES ,QUANTUM wells ,OSCILLATIONS - Abstract
We have measured at low temperatures the conductance of electron waveguides fabricated from modulation-doped quantum wells by wet etching and regrowth. We have found that, for a waveguide with abruptly changed geometry at the entrance and exit, the conductance shows oscillations, which are superimposed on a conventional conductance plateau structure. The periods and amplitudes of conductance oscillations depend on the length to width aspect ratio of the waveguide. In addition, the amplitudes of conductance oscillations decrease with increasing temperature. We propose that the observed oscillations are caused by the formation of longitudinal resonant electron states in the waveguide, in analogy with optical Fabry-Perot effects. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR] more...
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- 2000
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109. Growth of self-assembled InAs and InAs xP 1− x dots on InP by metalorganic vapour phase epitaxy
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Carlsson, N, Junno, T, Montelius, L, Pistol, M.-E, Samuelson, L, and Seifert, W
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- 1998
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110. MOVPE growth of [formula omitted] and [formula omitted] heterostructures for electronic transport applications
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Carlsson, N., Anand, S., Carlsson, S.-B., Gustafson, B., Omling, P., Ramvall, P., Samuelson, L., Seifert, W., and Wang, Q.
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- 1997
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111. The potential of bifidobacteria as a source of natural folate
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M R, D'Aimmo, P, Mattarelli, B, Biavati, N G, Carlsson, T, Andlid, D’Aimmo M. R., Mattarelli P., Biavati B., Carlsson N. G., and Andlid T.
- Subjects
BIFIDOBACTERIUM ,PROBIOTICS ,MICROBIOTA ,FUNCTIONAL FOOD ,Culture Media ,Intestines ,Folic Acid ,Fermentation ,FOLATE PRODUCTION ,Animals ,Humans ,Metagenome ,Dairy Products ,Intestinal Mucosa ,Chromatography, High Pressure Liquid - Abstract
Aims: Nineteen strains of bifidobacteria were screened for main folate forms composition in synthetic folate free and complex folate-containing media. Methods and Results: HPLC was used to analyze deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 μg/100g DM. The highest value of 9295 μg/100g DM was found in B. catenulatum ATCC 27539 and the lowest in B. animalis subsp. animalis ATCC 25527 containing 220 μg/100g DM. 10 strains grew in synthetic folate free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH3-H4folate and H4folate were strain dependent. 5-CH3-H4folate dominated in most strains. Conclusions: Our results show that bifidobacteria folate content and composition is dynamic, strain-specific and depends on medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass. Significance and Impact of Study: This suggests that certain bifidobacteria may contribute to the folate intake; either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota. more...
- Published
- 2012
112. Factors Associated With Symptoms of Prolonged Grief and Psychological Distress Among Bereaved Family Members of Persons Who Died From Sudden Cardiac Arrest.
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Carlsson N, Årestedt K, Alvariza A, Axelsson L, and Bremer A
- Abstract
Background: Death from sudden cardiac arrest implies a stressful and challenging situation for bereaved family members with an increased risk of prolonged grief disorder and psychological distress., Objectives: The aims of this study were (1) to explore the associations between symptoms of prolonged grief and psychological distress and (2) to identify factors associated with symptoms of prolonged grief and psychological distress among bereaved family members of persons who died from sudden cardiac arrest., Methods: This cross-sectional survey included bereaved adult family members. Demographic data and measures of prolonged grief (Prolonged Grief Disorder-13), anxiety and depression (Hospital Anxiety and Depression Scale), posttraumatic stress (Posttraumatic Stress Disorder Checklist for DSM-5), and perceived social support (Multidimensional Scale of Perceived Social Support) were analyzed using Spearman's correlations ( r s ) as well as univariate and multiple linear regression analyses., Results: In total, 108 family members participated. Significant associations between symptoms of prolonged grief, anxiety, depression, and posttraumatic stress were identified ( r s = 0.69-0.79, P < .001). Offered, sought, and/or received professional support from healthcare, lower levels of perceived social support, being a spouse of the deceased, female sex, younger age, and family presence during resuscitation were significantly associated with higher symptom levels of prolonged grief, anxiety, depression, and/or posttraumatic stress., Conclusions: The results indicate that family members with higher levels of symptoms were offered, sought, and/or received professional support. However, because a minority are offered professional support after deaths from cardiac arrest, future interventions need to proactively identify family members in need of support. Furthermore, perceived social support seems to be an important factor for family members of persons who died from cardiac arrest., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.) more...
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- 2023
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113. Symptoms of Prolonged Grief and Self-Reported Health Among Bereaved Family Members of Persons Who Died From Sudden Cardiac Arrest.
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Carlsson N, Alvariza A, Bremer A, Axelsson L, and Årestedt K
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- Adult, Humans, Self Report, Cross-Sectional Studies, Grief, Family, Death, Sudden, Cardiac, Bereavement, Heart Arrest
- Abstract
Sudden cardiac arrest is common and is one of the leading causes of death in the western world, and the sudden loss following cardiac arrest may have a significant impact on bereaved family members' health. Therefore, the aim of this study was to describe symptoms of prolonged grief and self-reported health among bereaved family members of persons who died from sudden cardiac arrest, with comparisons between spouses and non-spouses. This was a cross-sectional observation study with 108 adult family members who completed a questionnaire. A fifth of the family members reported prolonged grief, and problems with self-reported health were common, especially regarding anxiety. Spouses reported more problems with prolonged grief and self-reported health compared with non-spouses. The risk of these family members developing prolonged grief and health problems should be recognized, and professional support should be offered. more...
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- 2023
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114. Grief reactions in relation to professional and social support among family members of persons who died from sudden cardiac arrest: A longitudinal survey study.
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Carlsson N, Alvariza A, Axelsson L, Bremer A, and Årestedt K
- Abstract
Background: The loss of a close person from sudden cardiac arrest (CA) leaves family members at risk of developing grief reactions such as symptoms of prolonged grief, anxiety, depression, and posttraumatic stress. The aim was to describe longitudinal variations in grief reactions and its association with professional and social support among bereaved family members after a close person's death from sudden CA., Methods: This longitudinal multimethod survey included 69 bereaved family members who completed a questionnaire 6 and 12-months after the CA, including the Prolonged Grief Disorder-13, Hospital Anxiety and Depression Scale, PTSD Checklist for DSM-5, and Multidimensional Scale of Perceived Social Support. Qualitative data were collected by open-ended questions. Quantitative data was analyzed using Wilcoxon signed-rank test and linear regression analysis while written comments were analyzed using qualitative content analysis., Results: The median age was 62 years, 67 % were women, and 38 % had been present during the resuscitation attempts. Using the cut-off scores at the 6- and 12-month assessments respectively, 14 % and 17 % reported symptoms of prolonged grief, 32 % and 26 % symptoms of anxiety, 14 % and 9 % depression, and 4 % and 1 % posttraumatic stress. Professional and social support at the 6-month assessment were significantly associated with symptoms of prolonged grief, anxiety, depression, and/or posttraumatic stress at the 12-month assessments but could not predict any changes in the grief reactions., Conclusions: Family members' grief reactions point to the importance of proactive and available support over time to meet family members' needs., (© 2022 The Author(s).) more...
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- 2022
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115. Losing a close person following death by sudden cardiac arrest: Bereaved family members' lived experiences.
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Carlsson N, Bremer A, Alvariza A, Årestedt K, and Axelsson L
- Subjects
- Death, Sudden, Cardiac, Humans, Narration, Qualitative Research, Bereavement, Family
- Abstract
The death of a close person has profound impact on people's lives, and when death is sudden there are no possibilities to prepare for the loss. The study aimed to illuminate meanings of losing a close person following sudden cardiac arrest. A qualitative interpretive design was used, and twelve bereaved family members were interviewed. The results show a transition from pending between life and sudden loss during resuscitation and proceeding with life after the sudden loss. These results of being in liminality illuminate the family members' essential narration and the importance of compassionate care throughout this challenging transition. more...
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- 2022
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116. Measuring quality of life in life-threatening illness - content validity and response processes of MQOL-E and QOLLTI-F in Swedish patients and family carers.
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Axelsson L, Alvariza A, Carlsson N, Cohen SR, Sawatzky R, and Årestedt K
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- Adult, Caregivers psychology, Caregivers statistics & numerical data, Female, Humans, Interviews as Topic methods, Male, Middle Aged, Patients psychology, Patients statistics & numerical data, Psychometrics instrumentation, Psychometrics statistics & numerical data, Reproducibility of Results, Surveys and Questionnaires, Sweden, Translating, Psychometrics methods, Quality of Life psychology
- Abstract
Background: The McGill Quality of Life Questionnaire - Expanded (MQOL-E) and the Quality of Life in Life-Threatening Illness-Family Carer/Caregiver version (QOLLTI-F) are developed for use with patients facing the end of life and their family carers, respectively. They are also developed for possible use as companion instruments. Contemporary measurement validity theory places emphasis on response processes, i.e. what people feel and think when responding to items. Response processes may be affected when measurement instruments are translated and adapted for use in different cultures. The aim of this study was to translate and examine content validity and response processes during completion of MQOL-E and QOLLTI-F version 2 (v2) among Swedish patients with life-threatening illness and their family carers., Methods: The study was conducted in two stages (I) translation and adaptation (II) examination of content validity and response processes using cognitive interviews with 15 patients and 9 family carers. Participants were recruited from the hemodialysis unit, heart clinic, lung clinic and specialized palliative care of a Swedish county hospital. Patients had life-threatening illness such as advanced heart failure, advanced chronic obstructive pulmonary disease, end-stage kidney disease or advanced cancer. Patients were outpatients, inpatients or receiving home care., Results: Patients and family carers respectively believed that the items of the MQOL-E and QOLLTI-F v2 reflect relevant and important areas of their quality of life. Although some items needed more time for reflection, both instruments were considered easy to understand. Some changes were made to resolve issues of translation. Participants expressed that reflecting on their situation while answering questions was valuable and meaningful to them, and that responding was an opportunity to express feelings., Conclusions: The results of response processes pertaining to the Swedish translations of both MQOL-E and QOLLTI-F v2 contribute evidence regarding content validity, linguistic equivalence and cultural appropriateness of the translated instruments. In addition, results show that the instruments may support conversations on matters of importance for quality of life between patients and/or family carers and health care professionals. Further research is needed to study the psychometric properties of Swedish translations. more...
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- 2020
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117. Exploring experiences among adopters during the diffusion of a novel dance intervention in Sweden.
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Carlsson N, Kullberg A, Johansson IK, Bergman P, Skagerström J, and Andersson A
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- Adolescent, Diffusion of Innovation, Female, Humans, Male, Qualitative Research, Surveys and Questionnaires, Sweden, Attitude, Dancing psychology, Exercise psychology, Health Promotion, Health Services, Somatoform Disorders therapy, Stress, Psychological therapy
- Abstract
There is a demand for interventions aimed at adolescent girls with psychosomatic problems. In 2013, positive results were reported from a dance intervention programme addressing girls with internalizing problems. The research team behind the intervention immediately received requests from municipalities and county councils interested in using the intervention. From an implementation point of view it is unclear what made the intervention spread without an active plan. The aim of this study was to explore adopters' experiences about the diffusion and initiation of a public health intervention targeting adolescent girls with internalizing problems. Interviews were conducted with 12 people who were engaged in initiating the intervention in different settings. Data were analysed using conventional content analysis, yielding three categories: perceived appeal and trustworthiness, convenient information, and contextual factors. The results reflected that the participants found that there was a need for an intervention and found the dance intervention to be evidence based and not too complex to perform. Further, there was available information on the project which could easily be distributed to decision makers and others. When initiating the intervention, factors related to economy, possibility for collaboration and recruitment were of importance. more...
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- 2018
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118. A temperature-dependent physiologically based model for the invasive apple snail Pomacea canaliculata.
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Gilioli G, Pasquali S, Martín PR, Carlsson N, and Mariani L
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- Animals, Female, Fertility, Male, Population Dynamics, Reproduction, Temperature, Introduced Species, Models, Biological, Snails physiology
- Abstract
In order to set priorities in management of costly and ecosystem-damaging species, policymakers and managers need accurate predictions not only about where a specific invader may establish but also about its potential abundance at different geographical scales. This is because density or biomass per unit area of an invasive species is a key predictor of the magnitude of environmental and economic impact in the invaded habitat. Here, we present a physiologically based demographic model describing and explaining the population dynamics of a widespread freshwater invader, the golden apple snail Pomacea canaliculata, which is causing severe environmental and economic impacts in invaded wetlands and rice fields in Southeastern Asia and has also been introduced to North America and Europe. The model is based on bio-demographic functions for mortality, development and fecundity rates that are driven by water temperature for the aquatic stages (juveniles and adults) and by air temperature for the aerial egg masses. Our model has been validated against data on the current distribution in South America and Japan, and produced consistent and realistic patterns of reproduction, growth, maturation and mortality under different scenarios in accordance to what is known from real P. canaliculata populations in different regions and climates. The model further shows that P. canaliculata will use two different reproductive strategies (semelparity and iteroparity) within the potential area of establishment, a plasticity that may explain the high invasiveness of this species across a wide range of habitats with different climates. Our results also suggest that densities, and thus the magnitude of environmental and agricultural damage, will be largely different in locations with distinct climatic regimes within the potential area of establishment. We suggest that physiologically based demographic modelling of invasive species will become a valuable tool for invasive species managers. more...
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- 2017
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119. A fluorescence spectroscopy assay for real-time monitoring of enzyme immobilization into mesoporous silica particles.
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Nabavi Zadeh PS, Mallak KA, Carlsson N, and Åkerman B
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- Animals, Cattle, Enzymes, Immobilized chemistry, Kinetics, Molecular Structure, Benzopyrans chemistry, Furans chemistry, Ketones chemistry, Silicon Dioxide chemistry, Spectrometry, Fluorescence methods
- Abstract
Mesoporous silica particles are used as support material for immobilization of enzymes. Here we investigated a fluorescence-based assay for real-time monitoring of the immobilization of lipase, bovine serum albumin, and glucose oxidase into micrometer-sized mesoporous silica particles. The proteins are labeled with the dye epicocconone, and the interaction with the particles is observed as an increase in emission intensity of the protein-dye conjugates that can be quantified if correcting for a comparatively slow photobleaching. The immobilization occurs in tens of minutes to hours depending on particle concentration and type of protein. In the limit of excess particles over proteins, the formation of the particle-protein complexes can be described by a single exponential growth for all three investigated proteins, and the fitted pseudo-first-order rate constant increases linearly with particle concentration for each protein type. The derived second-order rate constant k varies with the protein hydrodynamic radius according to k∼RH(-4.70±0.01), indicating that the rate-limiting step at high particle concentrations is not the diffusional encounter between proteins and particles but rather the entry into the pores, consistent with the hydrodynamic radii of the three proteins being smaller but comparable to the pore radius of the particles., (Copyright © 2015 Elsevier Inc. All rights reserved.) more...
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- 2015
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120. Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.
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Rydberg HA, Kunze A, Carlsson N, Altgärde N, Svedhem S, and Nordén B
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- Amino Acid Sequence, Cell Membrane chemistry, Liposomes metabolism, Molecular Sequence Data, Phosphatidylcholines metabolism, Phosphatidylglycerols metabolism, Protein Structure, Secondary, Arginine, Cell Membrane metabolism, Peptides chemistry, Peptides metabolism, Quartz Crystal Microbalance Techniques, Tryptophan
- Abstract
Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions. more...
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- 2014
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121. Parents' experiences of participating in an intervention on tobacco prevention in Child Health Care.
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Johansson A, Carlsson N, Almfors H, Rosèn M, and Alehagen S
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- Adult, Child, Humans, Middle Aged, Pilot Projects, Young Adult, Child Welfare, Parents, Smoking Prevention
- Abstract
Background: Child health care is an important arena for tobacco prevention in Sweden. The aim of this study was to describe parents' experiences from participating in a nursebased tobacco prevention intervention., Methods: Eleven parents were interviewed using semi-structured interviews. The material was analysed in a qualitative content analysis process., Results: The analysis emerged four categories; Receiving support, Respectful treatment, Influence on smoking habits and Receiving information. The parents described how the CHC nurses treated them with support and respect. They described the importance of being treated with respect for their autonomy in their decisions about smoking. They also claimed that they had received little or no information about health consequences for children exposed to environmental tobacco smoke (ETS). The findings also indicate that both the questionnaire used and the urine-cotinine test had influenced parents' smoking., Conclusion: The clinical implication is that CHC is an important arena for preventive work aiming to minimize children's tobacco smoke exposure. CHC nurses can play an important role in tobacco prevention but should be more explicit in their communication with parents about tobacco issues. The SiCET was referred to as an eye-opener and can be useful in the MI dialogues nurses perform in order to support parents in their efforts to protect their children from ETS. more...
- Published
- 2014
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122. Enzymes immobilized in mesoporous silica: a physical-chemical perspective.
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Carlsson N, Gustafsson H, Thörn C, Olsson L, Holmberg K, and Åkerman B
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- Adsorption, Chemistry, Physical, Enzyme Activation, Enzymes metabolism, Enzymes, Immobilized metabolism, Models, Molecular, Particle Size, Porosity, Surface Properties, Enzymes chemistry, Enzymes, Immobilized chemistry, Silicon Dioxide chemistry
- Abstract
Mesoporous materials as support for immobilized enzymes have been explored extensively during the last two decades, primarily not only for biocatalysis applications, but also for biosensing, biofuels and enzyme-controlled drug delivery. The activity of the immobilized enzymes inside the pores is often different compared to that of the free enzymes, and an important challenge is to understand how the immobilization affects the enzymes in order to design immobilization conditions that lead to optimal enzyme activity. This review summarizes methods that can be used to understand how material properties can be linked to changes in enzyme activity. Real-time monitoring of the immobilization process and techniques that demonstrate that the enzymes are located inside the pores is discussed by contrasting them to the common practice of indirectly measuring the depletion of the protein concentration or enzyme activity in the surrounding bulk phase. We propose that pore filling (pore volume fraction occupied by proteins) is the best standard for comparing the amount of immobilized enzymes at the molecular level, and present equations to calculate pore filling from the more commonly reported immobilized mass. Methods to detect changes in enzyme structure upon immobilization and to study the microenvironment inside the pores are discussed in detail. Combining the knowledge generated from these methodologies should aid in rationally designing biocatalyst based on enzymes immobilized in mesoporous materials., (© 2013 Elsevier B.V. All rights reserved.) more...
- Published
- 2014
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123. How to minimize children's environmental tobacco smoke exposure: an intervention in a clinical setting in high risk areas.
- Author
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Carlsson N, Johansson A, Abrahamsson A, and Gäre BA
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- Child, Preschool, Cotinine urine, Female, Follow-Up Studies, Humans, Incidence, Infant, Infant, Newborn, Male, Parents, Retrospective Studies, Risk Factors, Smoking urine, Smoking Prevention, Surveys and Questionnaires, Sweden epidemiology, Tobacco Smoke Pollution statistics & numerical data, Smoking epidemiology, Smoking Cessation methods, Tobacco Smoke Pollution prevention & control
- Abstract
Background: Despite the low prevalence of daily smokers in Sweden, children are still being exposed to environmental tobacco smoke (ETS), primarily by their smoking parents. A prospective intervention study using methods from Quality Improvement was performed in Child Health Care (CHC). The aim was to provide nurses with new methods for motivating and supporting parents in their efforts to protect children from ETS exposure., Method: Collaborative learning was used to implement and test an intervention bundle. Twenty-two CHC nurses recruited 86 families with small children which had at least one smoking parent. Using a bundle of interventions, nurses met and had dialogues with the parents over a one-year period. A detailed questionnaire on cigarette consumption and smoking policies in the home was answered by the parents at the beginning and at the end of the intervention, when children also took urine tests to determine cotinine levels., Results: Seventy-two families completed the study. Ten parents (11%) quit smoking. Thirty-two families (44%) decreased their cigarette consumption. Forty-five families (63%) were outdoor smokers at follow up. The proportion of children with urinary cotinine values of >6 ng/ml had decreased., Conclusion: The intensified tobacco prevention in CHC improved smoking parents' ability to protect their children from ETS exposure. more...
- Published
- 2013
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124. Membrane interaction and secondary structure of de novo designed arginine-and tryptophan peptides with dual function.
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Rydberg HA, Carlsson N, and Nordén B
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- Amino Acid Sequence, Antimicrobial Cationic Peptides pharmacology, Circular Dichroism, Molecular Sequence Data, Protein Structure, Secondary, Proteus mirabilis drug effects, Pseudomonas aeruginosa drug effects, Staphylococcus drug effects, Staphylococcus aureus drug effects, Antimicrobial Cationic Peptides chemistry, Arginine chemistry, Cell Membrane chemistry, Tryptophan chemistry
- Abstract
Cell-penetrating peptides and antimicrobial peptides are two classes of positively charged membrane active peptides with several properties in common. The challenge is to combine knowledge about the membrane interaction mechanisms and structural properties of the two classes to design peptides with membrane-specific actions, useful either as transporters of cargo or as antibacterial substances. Membrane active peptides are commonly rich in arginine and tryptophan. We have previously designed a series of arg/trp peptides and investigated how the position and number of tryptophans affect cellular uptake. Here we explore the antimicrobial properties and the interaction with lipid model membranes of these peptides, using minimal inhibitory concentrations assay (MIC), circular dichroism (CD) and linear dichroism (LD). The results show that the arg/trp peptides inhibit the growth of the two gram positive strains Staphylococcus aureus and Staphylococcus pyogenes, with some individual variations depending on the position of the tryptophans. No inhibition of the gram negative strains Proteus mirabilis or Pseudomonas aeruginosa was noticed. CD indicated that when bound to lipid vesicles one of the peptides forms an α-helical like structure, whereas the other five exhibited rather random coiled structures. LD indicated that all six peptides were somehow aligned parallel with the membrane surface. Our results do not reveal any obvious connection between membrane interaction and antimicrobial effect for the studied peptides. By contrast cell-penetrating properties can be coupled to both the secondary structure and the degree of order of the peptides., (Copyright © 2012 Elsevier Inc. All rights reserved.) more...
- Published
- 2012
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125. Spectral properties and orientation of voltage-sensitive dyes in lipid membranes.
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Matson M, Carlsson N, Beke-Somfai T, and Nordén B
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- Molecular Structure, Quantum Theory, Unilamellar Liposomes chemistry, Fluorescent Dyes chemistry, Membranes, Artificial, Models, Biological, Phosphatidylcholines chemistry, Phosphatidylglycerols chemistry
- Abstract
Voltage-sensitive dyes are frequently used for probing variations in the electric potential across cell membranes. The dyes respond by changing their spectral properties: measured as shifts of wavelength of absorption or emission maxima or as changes of absorption or fluorescence intensity. Although such probes have been studied and used for decades, the mechanism behind their voltage sensitivity is still obscure. We ask whether the voltage response is due to electrochromism as a result of direct field interaction on the chromophore or to solvatochromism, which is the focus of this study, as result of changed environment or molecular alignment in the membrane. The spectral properties of three styryl dyes, di-4-ANEPPS, di-8-ANEPPS, and RH421, were investigated in solvents of varying polarity and in model membranes using spectroscopy. Using quantum mechanical calculations, the spectral dependence of monomer and dimer ANEPPS on solvent properties was modeled. Also, the kinetics of binding to lipid membranes and the binding geometry of the probe molecules were found relevant to address. The spectral properties of all three probes were found to be highly sensitive to the local environment, and the probes are oriented nearly parallel with the membrane normal. Slow binding kinetics and scattering in absorption spectra indicate, especially for di-8-ANEPPS, involvement of aggregation. On the basis of the experimental spectra and time-dependent density functional theory calculations, we find that aggregate formation may contribute to the blue-shifts seen for the dyes in decanol and when bound to membrane models. In conclusion, solvatochromic and other intermolecular interactions effects also need to be included when considering electrochromic response voltage-sensitive dyes. more...
- Published
- 2012
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126. The potential of bifidobacteria as a source of natural folate.
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D'Aimmo MR, Mattarelli P, Biavati B, Carlsson NG, and Andlid T
- Subjects
- Animals, Bifidobacterium genetics, Bifidobacterium metabolism, Chromatography, High Pressure Liquid, Culture Media, Dairy Products microbiology, Fermentation, Folic Acid analysis, Folic Acid genetics, Humans, Intestinal Mucosa metabolism, Intestines chemistry, Metagenome, Probiotics, Bifidobacterium growth & development, Folic Acid metabolism, Intestines microbiology
- Abstract
Aims: To screen 19 strains of bifidobacteria for main folate forms composition in synthetic folate-free and complex folate-containing media., Methods and Results: HPLC was used to analyse deconjugated folates extracted from bacterial biomass. Most strains had a total folate content above 4000 μg per 100 g dry matter (DM). The highest value of 9295 μg per 100 g DM was found in Bifidobacterium catenulatum ATCC 27539 and the lowest in Bifidobacterium animalis ssp. animalis ATCC 25527 containing 220 μg per 100 g DM. Ten strains grew in a synthetic folate-free medium (FFM), showing folate autotrophy and suggesting folate auxotrophy of the remaining nine. In the autotrophic strains, a consistently higher folate level was found in FFM as compared to a more complex folate-containing medium, suggesting reduced requirements for folates in the presence of growth factors otherwise requiring folates for synthesis. The contents of total folate, 5-CH(3) -H(4) folate and H(4) folate were strain dependent. 5-CH(3) -H(4) folate dominated in most strains., Conclusions: Our results show that bifidobacteria folate content and composition is dynamic, is strain specific and depends on the medium. Suitable selection of the growth conditions can result in high levels of folate per cell unit biomass., Significance and Impact of the Study: This suggests that certain bifidobacteria may contribute to the folate intake, either directly in foods, such as fermented dairy products, or in the intestine as folate-trophic probiotics or part of the natural microbiota., (© 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.) more...
- Published
- 2012
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127. Spectroscopic characterization of Coomassie blue and its binding to amyloid fibrils.
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Carlsson N, Kitts CC, and Åkerman B
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- Animals, Circular Dichroism, Indicators and Reagents chemistry, Insulin metabolism, Muramidase metabolism, Protein Binding, Protein Structure, Secondary, Rosaniline Dyes chemistry, Solvents chemistry, Spectrometry, Fluorescence, Spectrum Analysis methods, Viscosity, Amyloid chemistry, Amyloid metabolism, Indicators and Reagents metabolism, Rosaniline Dyes metabolism
- Abstract
Coomassie brilliant blue G-250 (CB) is the dye used frequently in the Bradford assay for protein concentration determination. In this study, we investigated how the solvent polarity and viscosity affect the CB absorption and fluorescence spectra and apply this understanding to investigate the binding of CB to lysozyme and insulin in the native and amyloid fibril states. Coomassie blue binds both to the native protein and to amyloid fibrils but gives distinctly different spectral responses. The absorption and fluorescence spectra of CB indicate that binding sites in the fibrils are less polar and hold the CB dye more rigidly than in the native forms. The spectral comparison of CB bound to the two different fibrils showed that the binding sites are different, and this was most likely due to differences in secondary structure as monitored by circular dichroism. Finally, linear dichroism was used to show that the fibril-bound CB is oriented preferentially parallel to the insulin amyloid fibril axis., (Copyright © 2011 Elsevier Inc. All rights reserved.) more...
- Published
- 2012
- Full Text
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128. "Smoking in Children's Environment Test": a qualitative study of experiences of a new instrument applied in preventive work in child health care.
- Author
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Carlsson N, Alehagen S, Andersson Gäre B, and Johansson A
- Subjects
- Child, Environmental Exposure adverse effects, Humans, Incidence, Smoking adverse effects, Smoking epidemiology, Smoking Cessation, Surveys and Questionnaires, Sweden epidemiology, Tobacco Smoke Pollution adverse effects, Child Health Services methods, Child Welfare, Environmental Exposure prevention & control, Health Knowledge, Attitudes, Practice, Nurses standards, Smoking Prevention, Tobacco Smoke Pollution prevention & control
- Abstract
Background: Despite knowledge of the adverse health effects of passive smoking, children are still being exposed. Children's nurses play an important role in tobacco preventive work through dialogue with parents aimed at identifying how children can be protected from environmental tobacco smoke (ETS) exposure. The study describes the experiences of Child Health Care (CHC) nurses when using the validated instrument SiCET (Smoking in Children's Environment Test) in dialogue with parents., Method: In an intervention in CHC centres in south-eastern Sweden nurses were invited to use the SiCET. Eighteen nurses participated in focus group interviews. Transcripts were reviewed and their contents were coded into categories by three investigators using the method described for focus groups interviews., Results: The SiCET was used in dialogue with parents in tobacco preventive work and resulted in focused discussions on smoking and support for behavioural changes among parents. The instrument had both strengths and limitations. The nurses experienced that the SiCET facilitated dialogue with parents and gave a comprehensive view of the child's ETS exposure. This gave nurses the possibility of taking on a supportive role by offering parents long-term help in protecting their child from ETS exposure and in considering smoking cessation., Conclusion: Our findings indicate that the SiCET supports nurses in their dialogue with parents on children's ETS exposure at CHC. There is a need for more clinical use and evaluation of the SiCET to determine its usefulness in clinical practice under varying circumstances., (© 2011 Carlsson et al; licensee BioMed Central Ltd.) more...
- Published
- 2011
- Full Text
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129. Parents' attitudes to smoking and passive smoking and their experience of the tobacco preventive work in child health care.
- Author
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Carlsson N, Johansson A, Hermansson G, and Andersson-Gäre B
- Subjects
- Child, Preschool, Cross-Sectional Studies, Female, Health Promotion, Humans, Infant, Male, Prenatal Care, Surveys and Questionnaires, Sweden, Attitude to Health, Parents psychology, Smoking, Tobacco Smoke Pollution
- Abstract
The purpose of this study was to describe parents' attitudes to smoking and their experience of the tobacco preventive work in antenatal care and in Child Health Care (CHC) in Sweden. A population based survey in which 62 percent of 3000 randomly selected parents with 1- and 3-year-old children answered a questionnaire. Fifty-six percent stated that smoking was registered in the health record of the child yet no further discussion regarding passive smoking took place. The parents' educational level and smoking status was related to the attitudes and experiences of the tobacco preventive work. The results indicated that the dialogue with parents regarding children and environmental tobacco smoke (ETS) exposure has to be redesigned and intensified in order to meet the needs of parents with different backgrounds. more...
- Published
- 2011
- Full Text
- View/download PDF
130. Direct probing of ion pair formation using a symmetric triangulenium dye.
- Author
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Westerlund F, Elm J, Lykkebo J, Carlsson N, Thyrhaug E, Akerman B, Sørensen TJ, Mikkelsen KV, and Laursen BW
- Subjects
- Benzene chemistry, Electrons, Liquid Crystals chemistry, Molecular Conformation, Quantum Theory, Spectrophotometry, Infrared, Coloring Agents chemistry, Ions chemistry, Pyrenes chemistry
- Abstract
The 2,6,10-tris(dialkylamino)trioxatriangulenium dyes (ATOTA(+)) are highly stabilised cationic chromophores with D(3h) symmetry. The symmetry gives rise to a degeneracy of the main electronic transition. In low polarity solvents significant splitting of this degenerate transition is observed and assigned to ion pair formation. Ion pairing of the 2,6,10-tris(dioctylamino)trioxatriangulenium ion with Cl(-), BF(4)(-), PF(6)(-) and TRISPHAT anions was studied using absorption spectroscopy. A clear correlation is found between the size of the anion and the splitting of the ATOTA(+) transitions. In benzene the Cl(-) salt displays a splitting of 1955 cm(-1), while the salt of the much larger TRISPHAT ion has a splitting of 1543 cm(-1). TD-DFT calculations confirm the splitting of the states and provide a detailed insight into the electronic structure of the ion pairs. The different degree of splitting in different ion pairs is found to correlate with the magnitude of the electric field generated in each ion pair, thus leading to the conclusion that the effect seen is an internal Stark effect. By insertion of an amphiphilic derivative of the ATOTA(+) chromophore in an oriented lamellar liquid crystal, it was possible to resolve the two bands of the double peak spectrum and show their perpendicular orientation in the molecular framework, as predicted by the calculations. more...
- Published
- 2011
- Full Text
- View/download PDF
131. Quantification of protein concentration by the Bradford method in the presence of pharmaceutical polymers.
- Author
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Carlsson N, Borde A, Wölfel S, Kerman B, and Larsson A
- Subjects
- Absorption, Acrylic Resins, Hydrogen-Ion Concentration, Hypromellose Derivatives, Methylcellulose chemistry, Optical Phenomena, Rosaniline Dyes metabolism, Solutions, Spectrum Analysis, Biochemistry methods, Chitosan chemistry, Methylcellulose analogs & derivatives, Ovalbumin analysis, Polyvinyls chemistry
- Abstract
We investigated how the Bradford assay for measurements of protein released from a drug formulation may be affected by a concomitant release of a pharmaceutical polymer used to formulate the protein delivery device. The main result is that polymer-caused perturbations of the Coomassie dye absorbance at the Bradford monitoring wavelength (595nm) can be identified and corrected by recording absorption spectra in the region of 350-850mm. The pharmaceutical polymers Carbopol and chitosan illustrate two potential types of perturbations in the Bradford assay, whereas the third polymer, hydroxypropylmethylcellulose (HPMC), acts as a nonperturbing control. Carbopol increases the apparent absorbance at 595nm because the polymer aggregates at the low pH of the Bradford protocol, causing a turbidity contribution that can be corrected quantitatively at 595nm by measuring the sample absorbance at 850nm outside the dye absorption band. Chitosan is a cationic polymer under Bradford conditions and interacts directly with the anionic Coomassie dye and perturbs its absorption spectrum, including 595nm. In this case, the Bradford method remains useful if the polymer concentration is known but should be used with caution in release studies where the polymer concentration may vary and needs to be measured independently., (Copyright © 2010 Elsevier Inc. All rights reserved.) more...
- Published
- 2011
- Full Text
- View/download PDF
132. Comparison of oligonucleotide migration in a bicontinuous cubic phase of monoolein and water and in a fibrous agarose hydrogel.
- Author
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Sanandaji N, Carlsson N, Voinova M, and Akerman B
- Subjects
- Electrophoresis, Agar Gel, Models, Theoretical, Glycerides chemistry, Hydrogels chemistry, Oligonucleotides chemistry, Sepharose chemistry, Water chemistry
- Abstract
Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. More recently lyotropic liquid crystals, such as the diamond cubic phase formed by the lipid monoolein and water, has become a new type of well-defined porous structure of interest for both hydrophilic and amphiphilic analytes. Here we compare these two types of matrixes by investigating the nature of retardation they confer to an oligonucleotide that migrates in their respective aqueous phases. The retardation for a 25-mer oligonucleotide was found to be about 35-fold stronger in the cubic phase than in an agarose hydrogel modified to have the same average pore size. According to modelling, the strong retardation is primarily due to the fact that hydrodynamic interaction with the continuous monoolein membrane is a stronger source of friction than the steric interactions (collisions) with discrete gel fibres. A secondary effect is that the regular liquid crystal has a narrower pore-size distribution than the random network of the agarose gel. In agreement with experiments, these two effects together predict that the retardation in the cubic phase is a 30-fold stronger than in an agarose gel with the same average pore radius. more...
- Published
- 2006
- Full Text
- View/download PDF
133. Bicontinuous cubic phase of monoolein and water as medium for electrophoresis of both membrane-bound probes and DNA.
- Author
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Carlsson N, Sanandaji N, Voinova M, and Akerman B
- Subjects
- DNA chemistry, Glycerides, Molecular Probes chemistry, Water, DNA isolation & purification, Electrophoresis methods, Molecular Probes isolation & purification
- Abstract
Porous hydrogels such as agarose are commonly used to analyze DNA and water-soluble proteins by electrophoresis. However, the hydrophilic environment of these gels is not suitable for separation of important amphiphilic molecules such as native membrane proteins. We show that an amphiphilic liquid crystal of the lipid monoolein and water can be used as a medium for electrophoresis of amphiphilic molecules. In fact, both membrane-bound fluorescent probes and water-soluble oligonucleotides can migrate through the same bicontinuous cubic crystal because both the lipid membrane and the aqueous phase are continuous. Both types of analytes exhibit a field-independent electrophoretic mobility, which suggests that the lipid crystal structure is not perturbed by their migration. Diffusion studies with four membrane probes indicate that membrane-bound analytes experience a friction in the cubic phase that increases with increasing size of the hydrophilic headgroup, while the size of the membrane-anchoring part has comparatively small effect on the retardation. more...
- Published
- 2006
- Full Text
- View/download PDF
134. Diamond cubic phase of monoolein and water as an amphiphilic matrix for electrophoresis of oligonucleotides.
- Author
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Carlsson N, Winge AS, Engström S, and Akerman B
- Subjects
- Diamond chemistry, Electrophoresis, Agar Gel methods, Glycerides chemistry, Oligonucleotides isolation & purification, Water chemistry
- Abstract
We used a cubic liquid crystal formed by the nonionic monoglyceride monoolein and water as a porous matrix for the electrophoresis of oligonucleotides. The diamond cubic phase is thermodynamically stable when in contact with a water-rich phase, which we exploit to run the electrophoresis in the useful submarine mode. Oligonucleotides are separated according to size and secondary structure by migration through the space-filling aqueous nanometer pores of the regular liquid crystal, but the comparatively slow migration means the cubic phase will not be a replacement for the conventional DNA gels. However, our demonstration that the cubic phase can be used in submarine electrophoresis opens up the possibility for a new matrix for electrophoresis of amphiphilic molecules. From this perspective, the results on the oligonucleotides show that water-soluble particles of nanometer size, typical for the hydrophilic parts of membrane-bound proteins, may be a useful separation motif. A charged contamination in the commercial sample of monoolein, most likely oleic acid that arises from its hydrolysis, restricts useful buffer conditions to a pH below 5.6. more...
- Published
- 2005
- Full Text
- View/download PDF
135. Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of Escherichia coli.
- Author
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Greiner R, Carlsson N, and Alminger ML
- Subjects
- Chromatography, High Pressure Liquid, Hydrolysis, Inositol Phosphates chemistry, Inositol Phosphates isolation & purification, Inositol Phosphates metabolism, Isomerism, Kinetics, Molecular Conformation, Phosphorylation, 6-Phytase metabolism, Escherichia coli enzymology, Phytic Acid chemistry, Phytic Acid metabolism
- Abstract
Using a combination of high-performance ion chromatography analysis and kinetic studies, the stereospecificity of myo-inositol hexakisphosphate dephosphorylation by the phytate-degrading enzyme P2 of Escherichia coli was established. High-performance ion chromatography revealed that the phytate-degrading enzyme P2 of E. coli degrades myo-inositol hexakisphosphate by stepwise dephosphorylation via D/L-Ins(1,2,3,4,5)P(5), D/L-Ins(2,3,4,5)P(4), D/L-Ins(2,4,5)P(3) or D/L-Ins(1,2,4)P(3), D/L-Ins(1,2)P(2) or Ins(2, 5)P(2) or D/L-Ins(4,5)P(2) to finally Ins(2)P or Ins(5)P. Kinetic parameters for myo-inositol pentakisphosphate hydrolysis by E. coli and wheat phytase, respectively, showed that the myo-inositol pentakisphosphate intermediate produced either by the phytate-degrading enzyme of wheat or E. coli are not identical. The absolute configuration of the myo-inositol pentakisphosphate isomer produced by the E. coli enzyme was determined by taking into consideration that wheat phytase produces predominantly the D-Ins(1, 2,3,5,6)P(5) isomer (Lim, P.E., Tate, M.E., 1973. The phytases: II. Properties of phytase fraction F(1) and F(2) from wheat bran and the myo-inositol phosphates produced by fraction F(2). Biochim. Biophys. Acta 302, 326-328). The data demonstrate that the phytate-degrading enzyme P2 of E. coli dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,3,4,5)P(5), D-Ins(2,3,4,5)P(4), D-Ins(2,4,5)P(3), Ins(2,5)P(2) to finally Ins(2)P (notation 6/1/3/4/5). more...
- Published
- 2001
- Full Text
- View/download PDF
136. Stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme of baker's yeast.
- Author
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Greiner R, Alminger ML, and Carlsson NG
- Subjects
- Chromatography, High Pressure Liquid, Isomerism, Kinetics, Phosphorylation, 6-Phytase metabolism, Inositol Phosphates chemistry, Inositol Phosphates metabolism, Saccharomyces cerevisiae enzymology
- Abstract
During food processing such as baking, phytate is dephosphorylated to produce degradation products, such as myo-inositol pentakis-, tetrakis-, tris-, bis-, and monophosphates. Certain myo-inositol phosphates have been proposed to have positive effects on human health. The position of the phosphate groups on the myo-inositol ring is thereby of great significance for their physiological functions. Using a combination of high-performance ion chromatography analysis and kinetic studies the stereospecificity of myo-inositol hexakisphosphate dephosphorylation by a phytate-degrading enzyme from baker's yeast (Saccharomyces cerevisiae) was established. The data demonstrate that the phytate-degrading enzyme from baker's yeast dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P(5), D-Ins(1,2,5,6)P(4), D-Ins(1,2,6)P(3), D-Ins(1,2)P(2), to finally Ins(2)P (notation 3/4/5/6/1). Knowledge of the absolute stereochemical specificity of the baker's yeast phytase allows use of the enzyme to produce defined myo-inositol phosphates for kinetic and physiological studies. more...
- Published
- 2001
- Full Text
- View/download PDF
137. Rapid analysis of inositol phosphates.
- Author
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Carlsson NG, Bergman EL, Skoglund E, Hasselblad K, and Sandberg AS
- Subjects
- Chromatography, Ion Exchange methods, Sensitivity and Specificity, Time Factors, Feces chemistry, Food Analysis, Inositol Phosphates analysis
- Abstract
Fast and simple analytical methods for the determination of inositol bis- to hexakisphosphates or only inositol hexakisphosphate in foods and feces are presented. The methods are both faster and simpler with regard to analytical detection and sample pretreatment as compared to previously reported methods. The samples are pretreated using extraction and centrifugal ultrafiltration and analyzed using high-performance ion chromatography (HPIC) with gradient or isocratic elution. The analytes are detected using ultraviolet detection after postcolumn reaction. The methods are efficient, highly selective, and appropriate for analyzing inositol phosphates in food and feces samples. The between- and within-day variances were generally below 8 and 5% (relative standard deviation), respectively, for the presented HPIC method with gradient elution. more...
- Published
- 2001
- Full Text
- View/download PDF
138. Production process for high-quality pea-protein isolate with low content of oligosaccharides and phytate.
- Author
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Fredrikson M, Biot P, Alminger ML, Carlsson NG, and Sandberg AS
- Subjects
- Biological Availability, Food Handling methods, Humans, Infant, Inositol Phosphates analysis, Molecular Weight, Ultrafiltration, Infant Food, Oligosaccharides isolation & purification, Pisum sativum chemistry, Phytic Acid isolation & purification, Plant Proteins, Dietary isolation & purification
- Abstract
A process for pea-protein isolate production, resulting in low content of phytate and oligosaccharides, has been developed. Oligosaccharides were removed from the protein fraction through ultrafiltration. Ultrafiltration of 50- and 100-kD molecular-weight cutoffs (MWCOs) were tested, and both effectively separated the oligosaccharides from the protein. Phytate degradation was achieved by incubation of the pea-protein solution by addition of exogenous phytase enzyme. An almost complete degradation of inositol hexa-, penta-, tetra-, and triphosphates was reached using an incubation time of 1 h. The reduced content of oligosaccharides and inositol phosphates is likely to result in reduced flatulence and improved mineral bioavailability. These qualities of the pea-protein isolate make it a suitable protein source for infant formula production. more...
- Published
- 2001
- Full Text
- View/download PDF
139. Inositol hexaphosphate hydrolysis by Baker's yeast. Capacity, kinetics, and degradation products.
- Author
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Türk M, Sandberg AS, Carlsson NG, and Andlid T
- Subjects
- 6-Phytase metabolism, Hydrolysis, Kinetics, Phytic Acid metabolism, Saccharomyces cerevisiae metabolism
- Abstract
Phytases hydrolyze myo-inositol 1,2,3,4,5,6-hexaphosphate (IP(6)), yielding lower inositol phosphates and inorganic orthophosphate. Two commercial strains of baker's yeast (Saccharomyces cerevisiae), Y(1) and Y(2), were able to express phytase activity. This was determined by the capacity to grow in a synthetic medium with IP(6) as the sole phosphorus source. IP(6) hydrolysis was rapid for both strains, and after 24 h, all IP(6) was degraded. Control cultures contained inorganic orthophosphate (P(i)) and no IP(6). Growth rate in IP(6) medium was for both strains essentially identical to growth in P(i) medium, indicating a well-adapted metabolism for utilization of phosphorus from IP(6). There was some difference in growth yield (milligrams of biomass per milligram of glucose) between the two strains: 0.95 (Y(1)) and 1.35 (Y(2)) in IP(6) medium and 1.03 and 1. 35, respectively, in P(i) medium. The phytases were of the 3-phytase type, forming mainly DL-Ins(1,2,4,5,6)P(5), DL-Ins(1,2,5,6)P(4), and DL-Ins(1,2,6)P(3). more...
- Published
- 2000
- Full Text
- View/download PDF
140. Inositol phosphates with different numbers of phosphate groups influence iron absorption in humans.
- Author
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Sandberg AS, Brune M, Carlsson NG, Hallberg L, Skoglund E, and Rossander-Hulthén L
- Subjects
- Absorption, Adolescent, Adult, Bread analysis, Female, Food Additives pharmacology, Humans, Male, Middle Aged, Phytic Acid pharmacology, Reference Values, Structure-Activity Relationship, Chelating Agents pharmacology, Inositol Phosphates pharmacology, Iron pharmacokinetics
- Abstract
Background: Inositol hexaphosphate (IP(6)) is a well-known inhibitor of iron absorption, whereas the effects of the less-phosphorylated derivatives of IP(6) are less known., Objectives: The objective was to investigate the effects of inositol tri-, tetra-, and pentaphosphates (IP(3), IP(4), and IP(5), respectively) on iron absorption in humans., Design: Iron absorption was measured in 5 experiments from single meals by extrinsic labeling with (55)Fe and (59)Fe and determination of whole-body retention and the erythrocyte uptake of isotopes. In experiments 1-3 the meals contained white-wheat rolls to which 10 mg P as IP(5), IP(4), or IP(3), respectively, was added. Inositol 1,2,6-triphosphate [Ins(1,2, 6)P(3)] and a mixture of isomers of IP(4) and IP(5) were studied. White-wheat rolls contained 10 mg P as IP(3) + IP(4) and 2 mg P as IP(5) + IP(6) in experiment 4 and 20 mg P as IP(3) + IP(4) and 3 mg P as IP(5) + IP(6) in experiment 5; inositol phosphates were obtained via fermentation of sodium phytate. Each experiment had 8-11 subjects., Results: In experiment 1, iron absorption was reduced by 39%, whereas there was no significant effect on iron absorption in experiments 2 and 3. In experiments 4 and 5, iron absorption was reduced by 54% and 64%, respectively, suggesting that IP(3) and IP(4) contributed to the inhibitory effect., Conclusions: IP(5) has an inhibitory effect on iron absorption, whereas IP(3) and IP(4) in isolated form have no such effect. IP(3) and IP(4) in processed food contribute to the negative effect on iron absorption, presumably by binding iron between different inositol phosphates. To improve iron absorption from cereals and legumes, degradation of inositol phosphates needs to be to less-phosphorylated inositol phosphates than IP(3). more...
- Published
- 1999
- Full Text
- View/download PDF
141. Alginate, small bowel sterol excretion, and absorption of nutrients in ileostomy subjects.
- Author
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Sandberg AS, Andersson H, Bosaeus I, Carlsson NG, Hasselblad K, and Härröd M
- Subjects
- Adolescent, Adult, Aged, Alginates pharmacology, Female, Glucuronic Acid, Hexuronic Acids, Humans, Intestinal Absorption, Male, Middle Aged, Alginates metabolism, Bile Acids and Salts metabolism, Cholesterol metabolism, Dietary Fiber administration & dosage, Digestive System metabolism, Ileostomy
- Abstract
The effect of alginate on ileostomy excretion of sterols and nutrients was investigated in six ileostomy subjects fed a constant low-fiber diet with or without supplementation with 7.5 g sodium alginate. A mean of 95% of uronic acids derived from the sodium alginate was recovered in the ileostomy contents. Supplementation with alginate increased fat excretion by 140% and decreased bile acids excretion by 12%. Sodium and potassium excretion were significantly increased whereas starch and nitrogen excretion were unchanged. Five of six subjects showed a decreased apparent absorption of iron and manganese with alginate, which, however, was not statistically significant. Absorption of phosphorus, calcium, magnesium, and zinc were unchanged. Almost no digestion of sodium alginate occurs in the stomach and small intestine. The increased fatty acids excretion may be explained by the binding or trapping of fatty acids in the gel matrix formed by alginate, which may also cause a reduced bile flow. more...
- Published
- 1994
- Full Text
- View/download PDF
142. Degradation products of bran phytate formed during digestion in the human small intestine: effect of extrusion cooking on digestibility.
- Author
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Sandberg AS, Andersson H, Carlsson NG, and Sandström B
- Subjects
- Dietary Fiber administration & dosage, Edible Grain, Energy Intake, Female, Humans, Male, Phytic Acid analysis, Cooking, Digestion, Intestine, Small metabolism, Phytic Acid metabolism
- Abstract
To investigate the digestion of phytate in the stomach and small intestine in humans, studies were performed in subjects with established ileostomy. A recently developed high performance liquid chromatography method made it possible to analyze phytate and its degradation products in food and digesta. The digestibility of phytate in raw bran and extruded bran was investigated in seven ileostomy patients. Each subject was studied for two 4-d periods while consuming a constant low fiber diet with the addition of either 54 g/d of a bran-gluten-starch mixture or the corresponding extruded product. During passage through the subject's stomach and small intestine 58%, on average, of the phytate in unprocessed bran was hydrolyzed to inositol penta-, tetra- and triphosphates. When bran was subjected to extrusion cooking, 25% of the inositol hexaphosphate was hydrolyzed to penta- and tetraphosphate and the phytase activity ceased. Essentially no phytate digestion occurred when the ileostomy subjects consumed the extruded product. The reduced digestibility might be due to the lost phytase activity or to formation of indigestible phytate complexes during extrusion cooking. more...
- Published
- 1987
- Full Text
- View/download PDF
143. Effect of wheat bran and pectin on bile acid and cholesterol excretion in ileostomy patients.
- Author
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Bosaeus I, Carlsson NG, Sandberg AS, and Andersson H
- Subjects
- Adult, Aged, Chenodeoxycholic Acid metabolism, Cholic Acid, Cholic Acids metabolism, Dietary Fiber metabolism, Female, Humans, Lipid Metabolism, Male, Middle Aged, Sterols metabolism, Bile Acids and Salts metabolism, Cholesterol metabolism, Dietary Fiber pharmacology, Ileostomy, Pectins pharmacology
- Abstract
The effect of addition of pectin or wheat bran to a constant low-fibre diet on bile acid and cholesterol excretion from the small intestine has been studied in ileostomy patients. The study was designed to minimize bacterial alteration of ileostomy contents. An addition of 15 g of citrus pectin increased bile acid excretion by 35 per cent (P less than 0.05) and net cholesterol excretion by 14 per cent (P less than 0.05) in six patients, while 16 g of wheat bran to another six patients caused no consistent change. Ileostomy fat excretion increased on the diet with added pectin (P less than 0.05) but not on that with bran. The results support the concept of dietary fibre exerting its effects on lipid metabolism by altering intestinal excretion of sterols. more...
- Published
- 1986
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