| 1. |
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| 2. |
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| 3. |
- Baykov, Alexander A., et al.
(author)
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Functional characterization of Escherichia coli inorganic pyrophosphatase in zwitterionic buffers
- 1999
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In: European Journal of Biochemistry. - : Wiley-Blackwell Publishing Inc.. - 0014-2956 .- 1432-1033. ; 260:2, s. 308-317
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Journal article (peer-reviewed)abstract
- Catalysis by Escherichia coli inorganic pyrophosphatase (E-PPase) was found to be strongly modulated by Tris and similar aminoalcoholic buffers used in previous studies of this enzyme. By measuring ligand-binding and catalytic properties of E-PPase in zwitterionic buffers, we found that the previous data markedly underestimate Mg2+-binding affinity for two of the three sites present in E-PPase (3.5- to 16-fold) and the rate constant for substrate (dimagnesium pyrophosphate) binding to monomagnesium enzyme (20- to 40-fold). By contrast, Mg2+-binding and substrate conversion in the enzyme-substrate complex are unaffected by buffer. These data indicate that E-PPase requires in total only three Mg2+ ions per active site for best performance, rather than four, as previously believed. As measured by equilibrium dialysis, Mg2+ binds to 2.5 sites per monomer, supporting the notion that one of the tightly binding sites is located at the trimer–trimer interface. Mg2+ binding to the subunit interface site results in increased hexamer stability with only minor consequences for catalytic activity measured in the zwitterionic buffers, whereas Mg2+ binding to this site accelerates substrate binding up to 16-fold in the presence of Tris. Structural considerations favor the notion that the aminoalcohols bind to the E-PPase active site.
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| 4. |
- Cunha, Maria Teresa, et al.
(author)
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Effect of electrolytes and surfactants on the thermoseparation of an ethylene oxide–propylene oxide random copolymer in aqueous solution
- 1998
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In: Journal of Chromatography. B. - 1387-2273. ; 711:1-2, s. 53-60
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Journal article (peer-reviewed)abstract
- The thermoseparation of aqueous solutions of Breox 50 A 1000, an ethylene oxide-propylene oxide 50:50 (w/w) random copolymer, was studied. The cloud-point diagram for Breox in water solution and the effects of electrolytes and surfactants on the cloud-point temperature (CPT) were determined. The Breox concentration in both phases after the thermoseparation was followed with a reversed-phase HPLC method. The effects of separation temperature and additives on phase composition were evaluated.
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| 5. |
- Dauter, Zbigniew, et al.
(author)
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Crystal Structure of dUTPase from Equine Infectious Anaemia Virus; Active Site Metal Binding in a Substrate Analogue Complex
- 1999
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In: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 285:2, s. 655-673
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Journal article (peer-reviewed)abstract
- The X-ray structures of dUTPase from equine infectious anaemia virus (EIAV) in unliganded and complexed forms have been determined to 1.9 and 2.0 A resolution, respectively. The structures were solved by molecular replacement using Escherichia coli dUTPase as search model. The exploitation of a relatively novel refinement approach for the initial model, combining maximum likelihood refinement with stereochemically unrestrained updating of the model, proved to be of crucial importance and should be of general relevance.EIAV dUTPase is a homotrimer where each subunit folds into a twisted antiparallel @b-barrel with the N and C-terminal portions interacting with adjacent subunits. The C-terminal 14 and 17 amino acid residues are disordered in the crystal structure of the unliganded and complexed enzyme, respectively. Interactions along the 3-fold axis include a water-containing volume (size 207 A3) which has no contact with bulk solvent.It has earlier been shown that a divalent metal ion is essential for catalysis. For the first time, a putative binding site for such a metal ion, in this case Sr2+, is established. The positions of the inhibitor (the non-hydrolysable substrate analogue dUDP) and the metal ion in the complex are consistent with the location of the active centre established for trimeric dUTPase structures, in which subunit interfaces form three surface clefts lined with evolutionary conserved residues. However, a detailed comparison of the active sites of the EIAV and E. coli enzymes reveals some structural differences. The viral enzyme undergoes a small conformational change in the uracil-binding @b-hairpin structure upon dUDP binding not observed in the other known dUTPase structures.
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| 7. |
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| 8. |
- Albin, Maria, et al.
(author)
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Asbestos and cancer
- 1995
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In: Medicina del Lavoro. - 0025-7818. ; 86:3, s. 259-262
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Journal article (peer-reviewed)
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| 9. |
- Albin, Maria, et al.
(author)
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Asbestos and cancer: An overview of current trends in Europe
- 1999
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In: Environmental Health Perspectives. - 1552-9924. ; 107:Suppl. 2, s. 289-298
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Journal article (peer-reviewed)abstract
- This review assesses the contribution of occupational asbestos exposure to the occurrence of mesothelioma and lung cancer in Europe. Available information on national asbestos consumption, proportions of the population exposed, and exposure levels is summarized. Population-based studies from various European regions on occupational asbestos exposure, mesothelioma, and lung cancer are reviewed. Asbestos consumption in 1994 ranged, per capita, between 0. 004 kg in northern Europe and 2.4 kg in the former Soviet Union. Population surveys from northern Europe indicate that 15 to 30% of the male (and a few percent of the female) population has ever had occupational exposure to asbestos, mainly in construction (75% in Finland) or in shipyards. Studies on mesothelioma combining occupational history with biologic exposure indices indicate occupational asbestos exposure in 62 to 85% of the cases. Population attributable risks for lung cancer among males range between 2 and 50% for definite asbestos exposure. After exclusion of the most extreme values because of methodologic aspects, most of the remaining estimates are within the range of 10 to 20%. Estimates of women are lower. Extrapolation of the results to national figures would decrease the estimates. Norwegian estimates indicate that one-third of expected asbestos-related lung cancers might be avoided if former asbestos workers quit smoking. The combination of a current high asbestos consumption per capita, high exposure levels, and high underlying lung cancer rates in Central Europe and the former Soviet Union suggests that the lung cancers will arise from the smoking-asbestos interaction should be a major concern.
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| 10. |
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| 11. |
- Barany, George, et al.
(author)
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Poly(ethylene glycol)-containing supports for solid-phase synthesis of peptides and combinatorial organic libraries.
- 1997
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In: Poly(ethylene glycol): Chemistry and Biological Applications, ACS Symp. Series. - Washington, DC : American Chemical Society. - 9780841235373 ; 680, s. 239-264
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Book chapter (pop. science, debate, etc.)abstract
- The choice of a polymeric support is a key factor for the success of solid-phase methods for syntheses of organic compounds and biomolecules such as peptides and oligonucleotides. Classical Merrifield solid-phase peptide synthesis, performed on low cross-linked hydrophobic polystyrene (PS) beads, sometimes suffers from sequence-dependent coupling difficulties. The concept of incorporating PEG into supports for solid-phase synthesis represents a successful approach to alleviating such problems. This chapter reviews the preparation of families of poly(ethylene glycol)-polystyrene (PEG-PS)graft as well as (highly) Cross-Linked Ethoxylate Acrylate Resin (CLEAR) supports developed in our laboratories, and demonstrates their applications to the syntheses of a wide range of targets in connection with numerous research objectives.
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| 12. |
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| 13. |
- Carlsson, Maria L., 1959, et al.
(author)
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The 5-HT2A receptor antagonist M100907 is more effective in counteracting NMDA antagonist- than dopamine agonist-induced hyperactivity in mice
- 1999
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In: J Neural Transm. - 0300-9564. ; 106:2, s. 123-9
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Journal article (peer-reviewed)abstract
- The purpose of the present study was to compare the effectiveness of the selective 5-HT2A antagonist M100907 in different psychosis models. The classical neuroleptic haloperidol was used as reference compound. Two hyperdopaminergia and two hypoglutamatergia mouse models were used. Hyperdopaminergia was produced by the DA releaser d-amphetamine or the DA uptake inhibitor GBR 12909. Hypoglutamatergia was produced by the un-competitive NMDA receptor antagonist MK-801 or the competitive NMDA receptor antagonist D-CPPene. M100907 was found to counteract the locomotor stimulant effects of the NMDA receptor antagonists MK-801 and D-CPPene, but spontaneous locomotion, d-amphetamine- and GBR-12909-induced hyperactivity were not significantly affected. Haloperidol, on the other hand, antagonized both NMDA antagonist- and DA agonist-induced hyperactivity, as well as spontaneous locomotion in the highest dose used. Based on the present and previous results we draw the conclusion that 5-HT2A receptor antagonists are particularly effective against behavioural anomalies resulting from hypoglutamatergia of various origins. The clinical implications of our results and conclusions would be that a 5-HT2A receptor antagonist, due to i a the low side effect liability, could be the preferable treatment strategy in various disorders associated with hypoglutamatergia; such conditions might include schizophrenia, childhood autism and dementia disorders.
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| 14. |
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| 15. |
- Gulda, K, et al.
(author)
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Quadrupole deformed and octupole collective bands in Ra-228
- 1998
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In: NUCLEAR PHYSICS A. - : ELSEVIER SCIENCE BV. - 0375-9474. ; 636:1, s. 28-46
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Journal article (peer-reviewed)abstract
- Spins and parities for collective states in Ra-228 have been determined from conversion electron measurements with a mini-orange beta spectrometer. The fast-timing beta gamma gamma(t) method has been used to measure lifetimes of T-1/2 = 550(20) ps and 181
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| 16. |
- Johansson, Maria, et al.
(author)
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Interactions between methylsulfonyl PCBs and the glucocorticoid receptor
- 1998
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In: Journal of Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 106:12, s. 769-772
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Journal article (peer-reviewed)abstract
- Persistent polychlorinated biphenyl (PCB) metabolites were studied with respect to their interaction with the human glucocorticoid receptor (GR). 3-Methylsulphonyl-2,5,6,2',4',5'-hexachlorobiphenyl (3-MeSO2-CB149) was shown to compete with 3H-dexamethasone for binding to the GR, with an IC50 (concentration that inhibits 50%) of approximately 1 microM. Using GRAF cells expressing human GR, glucocorticoid responsive element, and a reporter enzyme, we demonstrated that 3-MeSO2-CB149 functionally acts as an antagonist at the GR (IC50 = 2.7 microM). In accordance with the receptor binding, the antagonism mainly appeared to be of a competitive nature. When studying the competitive binding of 24 methylsulfonyl PCBs (relative to dexamethasone) to GR from mouse liver cytosol, seven compounds had a higher affinity to GR than 3-MeSO2-CB149. Structure-activity relationship studies indicated that the presence of three chlorine atoms in the ortho-position and chlorine and methyl sulfone groups on either end of the molecule (4 and 4'-position) increased the affinity to GR. The relevance of this finding for human health is not known, but PCB methyl sulfones are ubiquitous pollutants present in mother's milk. The results stress the need for studying endocrine disruptors that affect hormonal systems other than sex and thyroidogenic hormones.
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| 17. |
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| 18. |
- Lundqvist, Anders, et al.
(author)
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Altering the biochemical state of individual cultured cells and organelles with ultramicroelectrodes.
- 1998
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In: Proceedings of the National Academy of Sciences of the United States of America. - Univ Goteborg, Dept Chem, SE-41296 Goteborg, Sweden. Sahlgrens Univ Hosp, Inst Clin Neurosci, Dept Neurol, SE-41345 Goteborg, Sweden. : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 95:18, s. 10356-60
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Journal article (peer-reviewed)abstract
- We describe an efficient technique for the selective chemical and biological manipulation of the contents of individual cells. This technique is based on the electric-field-induced permeabilization (electroporation) in biological membranes using a low-voltage pulse generator and microelectrodes. A spatially highly focused electric field allows introduction of polar cell-impermeant solutes such as fluorescent dyes, fluorogenic reagents, and DNA into single cells. The high spatial resolution of the technique allows for design of, for example, cellular network constructions in which cells in close contact with each other can be made to possess different biochemical, biophysical, and morphological properties. Fluorescein, and fluo-3 (a calcium-sensitive fluorophore), are electroporated into the soma of cultured single progenitor cells derived from adult rat hippocampus. Fluo-3 also is introduced into individual submicrometer diameter processes of thapsigargin-treated progenitor cells, and a plasmid vector cDNA construct (pRAY 1), expressing the green fluorescent protein, is electroporated into cultured single COS 7 cells. At high electric field strengths, observations of dye-transfer into organelles are proposed.
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| 19. |
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| 20. |
- Persson, Hans, et al.
(author)
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Binding of Cu2+, Zn2+, and Cd2+ to Inositol Tri-, Tetra-, Penta-, and Hexaphosphates
- 1998
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In: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 46:8, s. 3194-3200
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Journal article (peer-reviewed)abstract
- myo-Inositol hexaphosphate, the salt of myo-inositol hexaphosphoric acid (IP6), is a common constituent of many plant foods, such as cereals and legumes. IP6 interacts with mineral elements, influencing their bioavailability. Processed foods contain a mixture of different inositol phosphates, i.e., IP6 and its degradation products with five or less phosphate groups (IP5-IP1). The interaction of the lower inositol phosphates with mineral elements is not well-known. In this study, the interaction between metal ions (Cu2+, Zn2+, and Cd2+) and isolated fractions of inositol phosphates with 6, 5, 4 and 3 phosphate groups (IP6-IP3) was investigated by using a potentiometric technique. The study was performed at pH 3-7, which is the pH range in the upper part of the duodenum, where mineral absorption takes place. The inositol phosphate fractions studied had a pronounced binding capacity between pH 5 and 7. Thus, mineral complex formation with lower inositol phosphates is likely to occur in the duodenum, which would be important from a nutritional point of view. The mineral binding capacity as calculated per phosphate group was similar for IP6, IP5, IP4, and IP3, but the binding strength was lower for the lower inositol phosphates (IP4 and IP3). At increasing pH, within the range (pH 3-7), the metal complex formation generally began in the order copper, zinc, cadmium for all inositol phosphates indicating the same order of binding strength, i.e., Cu > Zn > Cd. For IP6 the difference was small between Cu and Zn.
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| 21. |
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| 22. |
- Svanberg, S. J.Maria, et al.
(author)
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Effects of Boiling and Storage on Dietary Fibre and Digestible Carbohydrates in Various Cultivars of Carrots
- 1997
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In: Journal of the Science of Food and Agriculture. - 0022-5142. ; 73:2, s. 245-254
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Journal article (peer-reviewed)abstract
- The influence of boiling and storage on dietary fibre and digestible carbohydrates was investigated in eight different carrot cultivars. The content of total dietary fibre was in the range 252-291 g kg-1 DW and was generally at the higher end for the early cultivars and at the lower end for the late ones. During storage, there was a decrease in the soluble fibre content in all cultivars and generally an increase in insoluble fibre. Following boiling, the loss of dietary fibre varied considerably between cultivars. After storage, the loss could be correlated to the average root weight of the carrot cultivars. The total content of glucose, fructose and sucrose was rather similar in the various cultivars, whereas their individual distribution differed. Storage had generally minor influence on the sugar content, except in the cultivars Amarant and Bull. On boiling, the loss was solely dependent on the initial sugar concentration. After storage the loss increased, which could be related to the lower dry matter content. The choice of cultivar and storage time is important in interpreting analytical data from carrots and is probably of similar significance in other vegetables when studying effects of heat treatment.
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| 23. |
- Svanberg, S. J.Maria, et al.
(author)
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Molecular Weight Distribution, Measured by HPSEC, and Viscosity of Water-Soluble Dietary Fiber in Carrots following Different Types of Processing
- 1995
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In: Journal of Agricultural and Food Chemistry. - : American Chemical Society (ACS). - 0021-8561 .- 1520-5118. ; 43:10, s. 2692-2697
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Journal article (peer-reviewed)abstract
- The molecular weight distribution, measured by HPSEC, and the viscosity of the water-soluble dietary fiber isolated from variously processed/cooked carrots were investigated. The carrots were studied raw, frozen, blanched, soured, microwaved, and boiled. The fibers were isolated after enzymatic digestion of protein and starch to simulate the situation in the gastrointestinal tract. The degree of polymerization (DP) and the viscosity were highly dependent on the type of processing/cooking and in general followed the degree of heat treatment. Thus, the DP values were similar with raw and frozen carrots, whereas blanched carrots had a lower DP. Further, only minor differences in DP could be observed among blanched, soured, and microwaved material, and the most pronounced degradation was obtained in boiled material. The viscosity was in accordance with the DP measurements and decreased in the order raw > blanched > boiled.
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| 24. |
- Svanberg, S. J.Maria, et al.
(author)
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Physicochemical changes in dietary fiber of green beans after repeated microwave treatments
- 1997
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In: Journal of Food Science. - : Wiley. - 0022-1147 .- 1750-3841. ; 62:5, s. 1006-1010
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Journal article (peer-reviewed)abstract
- The influence of microwave cooking/reheating on dietary fiber in green beans was investigated. The beans were analyzed after blanching and following repeated microwave treatment. Content and composition of dietary fiber as well as molecular weight distribution and viscosity of indigestible water-soluble polysaccharides (WSP) (Mw >1000) were determined. Total fiber content decreased only after the most severe microwave treatment, primarily due to losses of soluble dietary fiber (pectic polymers). Molecular weight and viscosity decreased considerably after the first microwave treatment. Repeated microwave treatments reduced the molecular weight further, but not the viscosity.
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| 25. |
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