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1.
Rev Sci Instrum ; 94(7)2023 Jul 01.
Article in English | MEDLINE | ID: mdl-37409912

ABSTRACT

A recently developed method for analyzing the thermal conductivity vs depth variation near a sample surface has been extended to include inhomogeneous samples with anisotropy. If not considered, the anisotropy ratio in the sample structure can distort the depth-position data of the original test method. The anisotropy ratio is introduced in the original computational scheme in order to improve the depth-position estimations for inhomogeneous structures with anisotropy. The proposed approach has been tested in experiments and shown to improve depth position mapping.


Subject(s)
Anisotropy , Thermal Conductivity , Electric Conductivity
2.
Environ Res ; 225: 115372, 2023 05 15.
Article in English | MEDLINE | ID: mdl-36709027

ABSTRACT

In chemical risk assessment, measured or modelled environmental concentrations are compared to environmental exposure limits (EELs), such as Predicted No Effect Concentrations (PNECs) or hazardous concentrations for 5% of species (HC05s) derived from species sensitivity distributions (SSDs). However, for many chemicals the EELs include large uncertainties or, in the worst case, the necessary data for their estimation are completely missing. This makes the assessment of chemical risks and any subsequent implementation of management strategies challenging. In this study we analyzed the uncertainty of EELs and its impact on chemical risk assessment. First, we compared three individual EEL datasets, two primarily based on experimental data and one based on computational predictions. The comparison demonstrates large disagreements between EEL data sources, with experimentally derived EELs differing by more than seven orders of magnitude. In a case-study, based on the predicted emissions of 2005 chemicals, we showed that these uncertainties lead to significantly different risk assessment outcomes, including large differences in the magnitude of the total risk, risk driver identification, and the ranking of use categories as risk contributors. We also show that the large data-gaps in EEL datasets cannot be covered by commonly used computational approaches (QSARs). We conclude that an expanded framework for interpreting risk characterization outcomes is needed. We also argue that the large data-gaps present in ecotoxicological data need to be addressed in order to achieve the European zero pollution vision as the growing emphasis on ambient exposures will further increase the demand for accurate and well-established EELs.


Subject(s)
Environmental Exposure , Risk Assessment
3.
Chemosphere ; 287(Pt 1): 131854, 2022 Jan.
Article in English | MEDLINE | ID: mdl-34461333

ABSTRACT

Chemical emissions from households originate from a wide range of sources and results in highly diverse mixtures. This makes traditional monitoring based on analytical chemistry challenging, especially for compounds that appear in low concentrations. We therefore developed a method for predicting emissions of chemicals from households into wastewater, relying on consumption patterns from multiple data sources. The method was then used to predict the emissions of chemical preparations, chemicals leaching from textiles and prescription pharmaceuticals in Sweden. In total we predicted emissions of 2007 chemicals with a combined emission of 62,659 tonnes per year - or 18 g/person and day. Of the emitted chemicals, 2.0% (w/w) were either classified as hazardous to the environment or were both persistent and mobile. We also show that chemical emissions come from a wide range of uses and that the total emission of any individual chemical is determined primarily by its use pattern, not by the total amount used. This emphasizes the need for continuous updates and additional knowledge generation both on emission factors and excretion rates as well as a need for improved reporting on the intended use of individual chemicals. Finally, we scrutinize the model and its uncertainty and suggest areas that need improvement to increase the accuracy of future emission modelling. We conclude that emission modelling can help guide environmental monitoring and provide input into management strategies aimed at reducing the environmental effect caused by hazardous chemicals.


Subject(s)
Pharmaceutical Preparations , Wastewater , Environmental Monitoring , Hazardous Substances/analysis , Humans , Textiles
4.
Int J Dent Hyg ; 16(2): e103-e111, 2018 May.
Article in English | MEDLINE | ID: mdl-29210172

ABSTRACT

OBJECTIVES: Knowledge about the oral health and dental care habits of older immigrants is limited. The aim of this study was to explore dental service utilization, oral care habits, and attitudes to and knowledge about oral diseases and their prevention among older immigrants in Sweden. METHODS: A qualitative research method was used, and data were collected in individual interviews to gain a deeper understanding of the immigrants' views. Thirteen immigrants, seven women and six men, recruited from meeting places for older immigrants, participated, all aged between 59 and 88 (median 72 years). Interviews were tape-recorded and transcribed verbatim. Eight interviews were carried out with the help of an authorized interpreter. RESULTS: In the analytical process, performed using the content analysis method, meaning units were identified and condensed into codes which were labelled and grouped into subcategories and categories. The interview analysis resulted in four categories: Experiences of dental care, Attitudes, Barriers and Prevention of oral diseases. The elderly immigrants described a mix of regular and acute dental care and were often not satisfied with the outcome of the treatments. They stated that oral health was important and that they were responsible for their own teeth. Barriers to dental care were costs, language problems and lack of confidence in dental services. Daily oral hygiene routines were performed using a traditional chewing stick and/or regular toothbrush. CONCLUSION: The participants stated that, despite the barriers to treatment described above, they valued good oral health and visited dental services when they needed to.


Subject(s)
Dental Care/statistics & numerical data , Emigrants and Immigrants , Health Knowledge, Attitudes, Practice , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Oral Hygiene , Qualitative Research , Sweden
5.
Rev Sci Instrum ; 87(7): 074901, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27475584

ABSTRACT

Transient measurements of thermal conductivity are performed with hot disc sensors on samples having a thermal conductivity variation adjacent to the sample surface. A modified computational approach is introduced, which provides a method of connecting the time-variable to a corresponding depth-position. This allows highly approximate-yet reproducible-estimations of the thermal conductivity vs. depth. Tests are made on samples incorporating different degrees of sharp structural defects at a certain depth position inside a sample. The proposed methodology opens up new possibilities to perform non-destructive testing; for instance, verifying thermal conductivity homogeneity in a sample, or estimating the thickness of a deviating zone near the sample surface (such as a skin tumor), or testing for presence of other defects.

6.
Rev Sci Instrum ; 85(4): 044903, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24784644

ABSTRACT

A new method based on the adaptation of the Pulse Transient Hot Strip technique to slab sample geometry has been developed for studying thermal conductivity and thermal diffusivity of anisotropic thin film materials (<50 µm) with thermal conductivity in the 0.01-100 W/mK range, deposited on thin substrates (i.e., wafers). Strength of this technique is that it provides a well-controlled thermal probing depth, making it possible to probe a predetermined depth of the sample layer and thereby avoiding the influence from material(s) deeper down in the sample. To verify the technique a series of measurements were conducted on a y-cut single crystal quartz wafer. A Hot Strip sensor (32-µm wide, 3.2-mm long) was deposited along two orthogonal crystallographic (x- and z-) directions and two independent pulse transients were recorded. Thereafter, the data was fitted to our theoretical model, and the anisotropic thermal transport properties were determined. Using a thermal probing depth of only 30 µm, we obtained a thermal conductivity along the perpendicular (parallel) direction to the z-, i.e., optic axis of 6.48 (11.4) W/mK, and a thermal diffusivity of 3.62 (6.52) mm(2)/s. This yields a volumetric specific heat of 1.79 MJ/mK. These values agree well with tabulated data on bulk crystalline quartz supporting the accuracy of the technique, and the obtained standard deviation of less than 2.7% demonstrates the precision of this new measurement technique.

7.
Parasite Immunol ; 36(2): 78-86, 2014 Feb.
Article in English | MEDLINE | ID: mdl-24147800

ABSTRACT

The purpose of this study was to monitor local cytokine responses to Dictyocaulus viviparus in calves during primary infection and re-infection. Bronchoalveolar lavage fluid (BALF) was collected weekly from experimentally infected calves and interleukin-2 (IL-2), IL-4, IL-5, IL-10 and IFN-γ mRNA expression was quantified in BALF cells. The major finding was a prominent transient increase in IL-4 mRNA expression, compared with that of uninfected calves, observed in BALF cells collected 2-3 weeks post-primary D. viviparus infection. At 2 weeks post-infection, macroscopic worms were also first observed in BALF. Calves re-infected after 10 weeks were partially immune which was evident at slaughter 5 weeks post-infection as a lower worm burden than in previously naïve calves infected at the same time. IL-4 mRNA expression in BALF cells 2 weeks post-re-infection was increased compared with that of uninfected animals but not as high as that of primarily infected calves. BALF cell expression of the other cytokines tested for was not as clearly effected by the D. viviparus infection. It seems likely that the strong IL-4 response observed during primary infection reflects an innate response to the worms that may initiate an ensuing Th2 response, which confers protective immunity.


Subject(s)
Bronchoalveolar Lavage Fluid/immunology , Cattle Diseases/immunology , Dictyocaulus Infections/immunology , Dictyocaulus/immunology , Animals , Bronchoalveolar Lavage Fluid/cytology , Bronchoalveolar Lavage Fluid/parasitology , CD3 Complex/biosynthesis , CD3 Complex/genetics , Cattle , Cattle Diseases/metabolism , Cattle Diseases/parasitology , Cytokines/biosynthesis , Cytokines/genetics , Dictyocaulus/isolation & purification , Dictyocaulus/physiology , Dictyocaulus Infections/metabolism , Dictyocaulus Infections/parasitology , Interferon-gamma/biosynthesis , Interferon-gamma/genetics , Interleukin-10/biosynthesis , Interleukin-10/genetics , Interleukin-2/biosynthesis , Interleukin-2/genetics , Interleukin-4/biosynthesis , Interleukin-4/genetics , Interleukin-5/biosynthesis , Interleukin-5/genetics , Molecular Sequence Data , Parasite Load , RNA, Messenger/genetics , RNA, Messenger/metabolism , Real-Time Polymerase Chain Reaction , Recurrence , Time Factors
8.
Reprod Domest Anim ; 47 Suppl 6: 362-5, 2012 Dec.
Article in English | MEDLINE | ID: mdl-23279539

ABSTRACT

Canine herpesvirus (CHV) is a widespread infection among dogs that typically get latently infected after exposure and can reactivate the infection after stress. The aim of the present study was to study the effects of latent CHV infection during pregnancy on pregnancy outcome, and to study if there are signs of genital viral reactivation during pregnancy or during non-pregnant luteal phase. Twelve mated bitches and eight control bitches were followed and sampled regularly during pregnancy or non-pregnant luteal phase. Blood samples were taken for antibody analysis and vaginal swabs for real-time PCR analysis. Three of the pregnant bitches were vaccinated against CHV during pregnancy. All bitches had antibodies to CHV. Two pregnant bitches that were not vaccinated had a twofold or larger increase in CHV titre, with no negative effects detected on pregnancy. Higher titres were not associated with smaller litters or with vaccination. There was no consistent variation in antibody titres due to pregnancy or non-pregnant luteal phase. Vaginal excretion of CHV was not detected from any of the bitches.


Subject(s)
Dog Diseases/virology , Herpesviridae Infections/veterinary , Herpesvirus 1, Canid/isolation & purification , Luteal Phase , Pregnancy Complications, Infectious/veterinary , Pregnancy, Animal , Animals , Dog Diseases/blood , Dog Diseases/pathology , Dogs , Female , Herpesviridae Infections/blood , Herpesviridae Infections/pathology , Herpesviridae Infections/virology , Polymerase Chain Reaction/veterinary , Pregnancy , Pregnancy Complications, Infectious/blood , Pregnancy Complications, Infectious/pathology , Pregnancy Complications, Infectious/virology , Stillbirth
9.
Dement Geriatr Cogn Disord ; 32(3): 193-7, 2011.
Article in English | MEDLINE | ID: mdl-22057225

ABSTRACT

BACKGROUND/AIM: Detection of cerebrospinal fluid (CSF) biomarker deviations improve prediction of progression from mild cognitive impairment (MCI) to dementia. However, it is not settled whether the same pattern exists in patients progressing from very mild to more pronounced MCI. Given that neurodegenerative processes occur very early in the disease course, we also expected to find biomarker deviations in these patients. METHODS: A total of 246 memory clinic patients with non-progressive (n = 161), progressive (n = 19), or converting (n = 66) MCI, 67 with stable dementia, and 80 controls were followed for 24 months. At baseline, CSF total tau (T-tau), ß-amyloid 1-42 (Aß42) and the light subunit of neurofilament protein (NFL) were determined. RESULTS: Patients with converting MCI and stable dementia had lower CSF Aß42 concentrations and higher T-tau concentrations and NFL in comparison with controls and non-progressive/progressive MCI (p < 0.0005). No differences were found between progressive and non-progressive MCI. CONCLUSION: As expected, biomarker deviations predicted progression from MCI to dementia. Contrary to our hypothesis, progression from very mild MCI to more pronounced MCI was not reflected by biomarker deviations. The results suggest that the measured biomarkers are not early disease markers, or alternatively Alzheimer or vascular pathology is not the underlying cause in this patient group.


Subject(s)
Biomarkers/cerebrospinal fluid , Cognitive Dysfunction/cerebrospinal fluid , Cognitive Dysfunction/psychology , Aged , Alzheimer Disease/cerebrospinal fluid , Alzheimer Disease/psychology , Amyloid beta-Peptides/cerebrospinal fluid , Apolipoproteins E/blood , Dementia/cerebrospinal fluid , Dementia/psychology , Disease Progression , Educational Status , Electroencephalography , Female , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Neurofilament Proteins/cerebrospinal fluid , Neuropsychological Tests , Peptide Fragments/cerebrospinal fluid , Tomography, Emission-Computed, Single-Photon , tau Proteins/cerebrospinal fluid
10.
Dement Geriatr Cogn Disord ; 28(2): 110-5, 2009.
Article in English | MEDLINE | ID: mdl-19684400

ABSTRACT

UNLABELLED: The concept of the cognitive reserve (CR) hypothesizes that premorbid factors such as education enable compensation for the manifestation of brain pathology. Accordingly, pathology should be more prominent in individuals with higher CR before becoming clinically apparent. Previously, we found that patients subsequently converting to dementia with higher CR had lower concentrations of amyloid beta 42 (abeta42) as compared to patients with lower CR. However, the interaction between time, biomarkers, neuropsychological performance and CR is yet to be established. OBJECTIVE: To study the relation between biomarkers, neuropsychological performance and CR longitudinally. METHOD: A mixed between-within subject analysis of variance was performed for longitudinal analysis. Paired t tests were used for within group comparisons. RESULTS: Patients with higher CR (n = 15) had significantly lower concentrations of abeta42 at both time points compared to those with medium (n = 23) and lower CR (n = 28). Also, abeta42 concentrations decreased significantly from baseline to follow-up in patients with higher and medium CR. Groups performed comparably on neuropsychological tests. CONCLUSION: This study provides further support for the applicability of abeta42 as a substitute for pathology in relation to CR. Also, abeta42 reflects the disease progression in patients with higher and medium CR.


Subject(s)
Amyloid beta-Peptides/metabolism , Cognition Disorders/metabolism , Cognition Disorders/psychology , Cognition/physiology , Dementia/metabolism , Dementia/psychology , Peptide Fragments/metabolism , Aged , Biomarkers , Cognition Disorders/cerebrospinal fluid , Dementia/cerebrospinal fluid , Disease Progression , Female , Follow-Up Studies , Humans , Longitudinal Studies , Male , Middle Aged , Neuropsychological Tests
11.
Br J Radiol ; 82(976): 313-20, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19188246

ABSTRACT

The aim of this study was to investigate the effect of tube current on diagnostic image quality in paediatric cerebral multidetector CT (MDCT) images in order to identify the minimum radiation dose required to reproduce acceptable levels of different diagnostic image qualities. Original digital scanning data (raw data) were selected retrospectively from routine MDCT brain examinations of 25 paediatric patients. All examinations had been performed using axial scanning on an eight-slice MDCT (LightSpeed Ultra, GE Healthcare). Their ages ranged from newborn to 15 years. Quantum noise was added artificially to the raw data representing dose reductions equivalent to steps of 20 mA. Patient identification information was removed. Three experienced radiologists blindly and randomly assessed the resulting images from two different levels of the brain with regard to reproduction of structures and overall image quality. Final data were evaluated using the non-parametric statistical approach of inter-scale concordance. The minimum value of tube current-time product (mAs) required to reproduce an image of sufficient diagnostic quality was established in relation to the age of the patient. The corresponding CT dose index values by volume (CTDI(vol) (mGy)) were also established. In conclusion, acceptable reproduction of low-contrast structures was possible at CTDI(vol) values down to 20 mGy (patients 1-5 years old). For acceptable reproduction of high-contrast structures, CTDI(vol) values down to 10 mGy were considered possible (patients 1-5 years old). The original image quality for patients under 6 months of age (15 mGy) was found to be inadequate for acceptable reproduction of low-contrast structures.


Subject(s)
Brain/diagnostic imaging , Neoplasms, Radiation-Induced/prevention & control , Tomography, X-Ray Computed/adverse effects , Adolescent , Age Factors , Child , Child, Preschool , Clinical Protocols , Dose-Response Relationship, Radiation , Female , Humans , Infant , Male , Radiation Dosage , Radiographic Image Interpretation, Computer-Assisted , Reference Values , Reproducibility of Results , Retrospective Studies , Tomography, X-Ray Computed/instrumentation
12.
Dement Geriatr Cogn Disord ; 27(2): 194-200, 2009.
Article in English | MEDLINE | ID: mdl-19225233

ABSTRACT

BACKGROUND: The concept of the cognitive reserve (CR) posits that factors such as education enable compensation for the effect of brain pathology. Consequently, pathology should be more pronounced in individuals with higher CR before becoming clinically apparent. Biomarkers such as total tau (t-tau) and beta-amyloid 42 (Abeta42) may be surrogates for pathology in relation to CR in patients with neurodegenerative disease. OBJECTIVE: To examine the applicability of biomarkers as surrogates for pathology in relation to the CR in patients with mild cognitive impairment (MCI) either converting to dementia or remaining stable at follow-up. METHOD: Comparisons of baseline t-tau, Abeta42, educational years and global cognition for MCI patients either converting to dementia (n = 57) or remaining stable (n = 91) were made. Patients converting to dementia were grouped on the basis of educational level and compared considering biomarkers and neuropsychological tests. RESULTS: Stable MCI patients were better educated, performed better cognitively, had higher Abeta42 levels and lower levels of t-tau. Converting MCI patients with higher education had lower levels of Abeta42 and performed equally in neuropsychological tests compared to those with lower education. CONCLUSION: Our results suggest that highly educated MCI patients subsequently converting to dementia display more amyloid pathology.


Subject(s)
Cognition Disorders/psychology , Cognition/physiology , Aged , Amyloid beta-Peptides/metabolism , Attention/physiology , Biomarkers , Cognition Disorders/genetics , Cognition Disorders/metabolism , Dementia/psychology , Disease Progression , Education , Female , Humans , Learning/physiology , Male , Memory/physiology , Middle Aged , Neuropsychological Tests , Peptide Fragments/metabolism , Psychomotor Performance/physiology , Visual Perception/physiology , tau Proteins/metabolism
13.
Phys Rev Lett ; 100(8): 080404, 2008 Feb 29.
Article in English | MEDLINE | ID: mdl-18352606

ABSTRACT

We report on the control of interaction-induced dephasing of Bloch oscillations for an atomic Bose-Einstein condensate in an optical lattice. We quantify the dephasing in terms of the width of the quasimomentum distribution and measure its dependence on time for different interaction strengths which we control by means of a Feshbach resonance. For minimal interaction, the dephasing time is increased from a few to more than 20 thousand Bloch oscillation periods, allowing us to realize a BEC-based atom interferometer in the noninteracting limit.

14.
Radiat Prot Dosimetry ; 114(1-3): 313-6, 2005.
Article in English | MEDLINE | ID: mdl-15933128

ABSTRACT

The purpose of this study was to develop an equation with which to determine the tube current to be used in order to obtain a certain image noise level for differently sized children undergoing multi-slice computed tomography examination. The relationship between image noise and detector dose for different examination protocols was established for a LightSpeed Ultra, an eight slice CT from GEMS, using homogeneous water phantoms of different sizes. Three different anatomical areas (head, thorax and abdomen) were studied in 111 patients between 0 and 17 y of age. The mean ratio between the calculated and the measured noise in patient images was established for the different areas. Head examinations showed the best correlation (measured-to-calculated noise ratio = 1.01). In the thorax, the calculated noise was generally higher than the measured noise (ratio = 0.74), and in the abdomen, the opposite result was found (ratio = 1.20).


Subject(s)
Radiographic Image Interpretation, Computer-Assisted/methods , Tomography, X-Ray Computed/instrumentation , Tomography, X-Ray Computed/methods , Artifacts , Head/diagnostic imaging , Humans , Phantoms, Imaging , Radiation Dosage , Radiographic Image Enhancement , Radiography, Abdominal/methods , Radiography, Thoracic/methods , Tomography Scanners, X-Ray Computed , Water/chemistry
15.
Environ Toxicol Chem ; 21(11): 2401-11, 2002 Nov.
Article in English | MEDLINE | ID: mdl-12389920

ABSTRACT

The Baltic Sea is a heavily polluted area. To assess the current contaminant pressure on the common guillemot (Uria aalge) living there, whole-body extracts of guillemots from the Baltic Sea were prepared and subdivided over six fractions, which differed in composition due to lipophilicity and polarity of the contaminants. The fractions were tested in the chicken embryo assay and compared to fractions of Atlantic guillemot extracts. Fertilized chicken eggs were injected with 0.03, 0.3, or 3 bird egg equivalents (BEQ) of the contaminants present in the fractions and then incubated for 19 d. Endpoints were selected to cover several mechanisms that may play a role in reproductive failures of fish-eating birds. Fractions I and IV from the Baltic guillemots induced ethoxyresorufin-O-deethylase (EROD) activity up to 15-fold in embryos exposed to 0.3 BEQ and up to 17-fold in embryos exposed to 3 BEQ. Corresponding Atlantic fractions induced EROD activity only at the higher dose of 3 BEQ. Morphological alterations were observed in the bursa of Fabricius in embryos exposed to the fractions that induced EROD, and for the Baltic fractions, this was apparent at the dose of 0.3 BEQ. The higher toxic potency of fractions I and IV was confirmed by higher mortality and occurrence of malformations among embryos exposed to these fractions. No other effects were observed; morphometry, hepatic porphyrin levels, thiamine-dependent enzymes, and acetylcholinesterase activity were not affected by any fraction. During interpretation of the results, concentrations in the whole-body guillemot extracts were compared to concentrations reported in field studies. In general, concentrations in the guillemot extract were lower than those associated with biomarker responses in other wild-bird species. However, because the relative sensitivity of guillemot toward immunotoxic effects remains to be resolved, effects on the immunocompetence of guillemot could not be excluded.


Subject(s)
Birds/metabolism , Embryo, Nonmammalian/drug effects , Environmental Exposure/adverse effects , Organic Chemicals/toxicity , Teratogens/toxicity , Water Pollutants, Chemical/toxicity , Animals , Animals, Wild , Atlantic Ocean , Birds/embryology , Bursa of Fabricius/drug effects , Bursa of Fabricius/pathology , Cytochrome P-450 CYP1A1/biosynthesis , Enzyme Induction , Food Chain , Norway , Organic Chemicals/analysis , Sweden , Teratogens/analysis , Water Pollutants, Chemical/analysis
16.
Protein Eng ; 14(9): 711-5, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11707619

ABSTRACT

Fusion proteins composed of a cellulose-binding domain from Neocallimastix patriciarum cellulase A and Candida antarctica lipase B were constructed using different linker peptides. The aim was to create proteolytically stable linkers that were able to join the functional modules without disrupting their function. Six fusion variants containing linkers of 4-44 residues were expressed in Pichia pastoris and analysed. Three variants were found to be stable throughout 7-day cultivations. The cellulose-binding capacities of fusion proteins containing short linkers were slightly lower compared with those containing long linkers. The lipase-specific activities of all variants, in solution or immobilized on to cellulose, were equal to that of the wild-type lipase.


Subject(s)
Cellulase/chemistry , Cellulose/metabolism , Lipase/genetics , Lipase/metabolism , Pichia/genetics , Protein Engineering/methods , Amino Acid Sequence , Binding Sites , Candida/enzymology , Enzyme Stability , Fungal Proteins , Gene Expression , Genetic Variation , Genetic Vectors , Glycosylation , Hydrolysis , Lipase/isolation & purification , Neocallimastix/enzymology , Peptides/chemistry , Peptides/genetics , Pichia/chemistry , Plasmids , Protein Structure, Tertiary , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/isolation & purification , Recombinant Fusion Proteins/metabolism , Time Factors
17.
Protein Expr Purif ; 21(3): 386-92, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11281712

ABSTRACT

Candida antarctica lipase B (CALB) and C. antarctica lipase B fused to a cellulose-binding domain (CBD-CALB) were expressed functionally in the methylotrophic yeast Pichia pastoris. The cellulose-binding domain originates from cellulase A of the anaerobic rumen fungus Neocallimastix patriciarum. The genes were fused to the alpha-factor secretion signal sequence of Saccharomyces cerevisiae and placed under the control of the alcohol oxidase gene (AOX1) promoter. The recombinant proteins were secreted into the culture medium reaching levels of approximately 25 mg/L. The proteins were purified using hydrophobic interaction chromatography and gel filtration with an overall yield of 69%. Results from endoglycosidase H digestion of the proteins showed that CALB and CBD-CALB were N-glycosylated. The specific hydrolytic activities of recombinant CALB and CBD-CALB were identical to that reported for CALB isolated from its native source. The fusion of the CBD to the lipase resulted in a greatly enhanced binding toward cellulose for CBD-CALB compared with that for CALB.


Subject(s)
Candida/enzymology , Cellulose/metabolism , Lipase/biosynthesis , Pichia/genetics , Recombinant Fusion Proteins/biosynthesis , Adsorption , Binding Sites , Blotting, Western , Candida/genetics , Electrophoresis, Polyacrylamide Gel , Gene Expression , Genetic Engineering , Glycosylation , Hydrolysis , Lipase/genetics , Lipase/isolation & purification , Lipase/metabolism , Molecular Weight , Protein Binding , Protein Structure, Tertiary , Recombinant Fusion Proteins/chemistry , Recombinant Fusion Proteins/isolation & purification , Recombinant Fusion Proteins/metabolism , Time Factors , Triglycerides/metabolism
18.
Bioelectromagnetics ; 22(2): 87-90, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11180253

ABSTRACT

Some epidemiological studies indicate an association between extremely low frequency electromagnetic field (ELF-EMF) exposure and cancer risks. These studies have mainly taken residential and occupational exposure into consideration. Outdoor environments are often considered as low level areas, but in this paper we show that this is not true in a city environment. We have mapped the ELF magnetic flux densities along certain stretches of sidewalk in central Göteborg City, Sweden. About 50% of the investigated street length shows flux densities of the same order of magnitude (0.2 microT and above) as those associated with increased risks of cancer in epidemiological studies. We conclude that the outdoor exposures in a city environment also should be considered in exposure assessments and risk evaluations. These elevated flux densities are probably due to stray currents. We also found strong magnetic flux densities (> 1.0 microT) close to ordinary distribution pillars, power substations, shoplifting alarms, and other electrical devices.


Subject(s)
Electromagnetic Fields/adverse effects , Urban Health , Environmental Exposure , Humans , Neoplasms/etiology , Risk Factors , Sweden
19.
Scand J Immunol ; 53(2): 121-31, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11169215

ABSTRACT

In the present study, the nature of hyperacute xenograft rejection was closely studied in a vascularized mouse-to-rat transplantation model. Antibodies against mouse heart, erythrocytes and lymphocytes and against the Forssman antigen were raised in the rat. Upon heterotopic heart transplantation the respective antisera were intravenously (i.v.) injected. Passive transfer of antiheart, antierythrocyte or antilymphocyte serum resulted in hyperacute rejection of the transplanted mouse heart. Subfractionation of the antiheart serum showed that the capacity to induce hyperacute rejection was carried by the immunoglobulin (Ig)G fraction. When antierythrocyte serum adsorbed with mouse erythrocytes was administered the cardiac grafts remained beating. To the contrary, antilymphocyte serum adsorbed with erythrocytes still had the capacity to induce hyperacute rejection. None of the rats that had previously been challenged with the Forssman antigen rejected their grafts hyperacutely. Subsequent investigations by electron microscopy revealed that the Forssman antigen is expressed on dendritic cells (DC) adjacent to the vessels, but not on the vascular endothelium, thus explaining the inability of the anti-Forssman serum to induce hyperacute rejection. Taken together, we have demonstrated the existence of several xenoantigens that can be targets for antibody-mediated rejection, suggesting that more than one relevant xenoantigen exists also in more distantly related combinations, such as the pig-to-human combination.


Subject(s)
Antibodies, Heterophile/immunology , Antigen-Antibody Reactions , Antigens, Heterophile/immunology , Aorta/immunology , Coronary Vessels/immunology , Endothelium, Vascular/immunology , Forssman Antigen/immunology , Heart Transplantation/immunology , Transplantation, Heterologous/immunology , Acute Disease , Animals , Antilymphocyte Serum/pharmacology , Aorta/pathology , Carbohydrate Sequence , Coronary Vessels/pathology , Dendritic Cells/immunology , Endothelium, Vascular/pathology , Erythrocytes/immunology , Glycolipids/immunology , Graft Rejection/immunology , Graft Rejection/pathology , Immunization , Immunization, Passive , Immunoglobulin G/immunology , Mice , Mice, Inbred BALB C , Mice, Inbred C57BL , Microscopy, Electron , Molecular Sequence Data , Myocardium/immunology , Rats , Rats, Inbred Lew , Rats, Inbred Strains , Species Specificity , Transplantation, Heterotopic
20.
Scand J Immunol ; 53(2): 171-5, 2001 Feb.
Article in English | MEDLINE | ID: mdl-11169221

ABSTRACT

Biopsies are difficult to perform in rodent heart transplant models without compromising the graft function and therefore other means to evaluate the grafts repeatedly and noninvasively are warranted. The goal of the present study was to measure changes in ratios of high energy phosphorus containing metabolites detected with in vivo 31Phosphorous Magnetic Resonance Spectroscopy ((31)P MRS) in a xenotransplantation model and to investigate if these ratios correlated to histological signs of acute xenograft rejection. Thirty-five heart transplantations were performed (NMRI-mice to Lewis (RT1(1)) rats). Thirteen heart transplants underwent repeated daily in vivo (31)P MRS measurements and 22 grafts were measured on any of 4 postoperative days and thereafter sacrificed for histology. A modified scoring system based on Billingham's criteria was used to stage the rejection process. The median graft survival was 3.0 +/- 0.44 (median +/- SD) days (n = 17). Significant differences, both overall and interday, could be calculated for the phosphocreatine (PCr)/beta-adenosine triphosphate (beta-ATP) ratios and for the rejection score. The decreases in PCr/beta-ATP ratios correlated significantly to the progressive acute rejection process in the sacrificed grafts (P = 0.01). Further studies are indicated to establish the potential of (31)P MRS in immunosuppressed recipients of vascularized xenotransplants with prolonged graft survival.


Subject(s)
Adenosine Triphosphate/analysis , Graft Rejection/metabolism , Heart Transplantation/immunology , Magnetic Resonance Spectroscopy/methods , Myocardium/chemistry , Phosphocreatine/analysis , Phosphorus Isotopes/analysis , Transplantation, Heterologous/immunology , Acute Disease , Animals , Energy Metabolism , Graft Rejection/diagnosis , Male , Mice , Mice, Inbred Strains , Myocardial Contraction , Postoperative Period , Rats , Rats, Inbred Lew , Transplantation, Heterotopic
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