| 1. |
- Dudman, N. P. B., et al.
(författare)
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Disordered methionine/homocysteine metabolism in premature vascular disease. Its occurrence, cofactor therapy, and enzymology
- 1993
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Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - : American Heart Association. - 1079-5642 .- 1524-4636. ; 13:9, s. 1253-1260
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Tidskriftsartikel (refereegranskat)abstract
- Mild homocysteinemia occurs surprisingly often in patients with premature vascular disease. We studied the possible enzymatic sources of this mild hyperhomocysteinemia and the control of homocysteine levels in plasma by treatment of patients with the cofactors and cosubstrates of homocysteine catabolism. We assessed homocysteine metabolism in 131 patients who had premature disease in their coronary, peripheral, or cerebrovascular circulation by using a standard oral methionine-load test. Impaired homocysteine metabolism occurred in 28 patients. We assayed levels of the primary enzymes of homocysteine catabolism in cultured skin fibroblast extracts from 15 of these 28 patients. The patients' cystathionine beta-synthase levels (3.68 +/- 2.52 nmol/h per milligram of cell protein, mean +/- SD) were markedly depressed compared with those from 31 healthy adult control subjects (7.61 +/- 4.49, P < .001). The patients' levels of 5-methyltetrahydrofolate: homocysteine methyltransferase were normal. While betaine: homocysteine methyltransferase was not expressed in skin fibroblasts, 24-hour urinary betaine and N,N-dimethylglycine measurements were consistent with normal or enhanced remethylation of homocysteine by betaine: homocysteine methyltransferase in the 13 patients tested. When treated daily with choline and betaine, pyridoxine, or folic acid, there was a normalization of the postmethionine plasma homocysteine level in 16 of 19 patients. Our results indicate that mild homocysteinemia in premature vascular disease may be caused by either a folate deficiency or deficiencies in cystathionine beta-synthase activity. It does not necessarily involve deficiencies of either 5-methyltetrahydrofolate:homocysteine methyltransferase or betaine:homocysteine methyltransferase. Effective treatment regimens are also defined.
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| 2. |
- Hirsch, Jan M, et al.
(författare)
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Hemodynamic effects of the use of oral snuff
- 1992
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Ingår i: Clinical Pharmacology and Therapeutics. - : Springer Science and Business Media LLC. - 0009-9236 .- 1532-6535. ; 52:4, s. 394-401
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Tidskriftsartikel (refereegranskat)abstract
- The hemodynamic effects during rest and exercise of oral snuff were investigated in an open, placebo-controlled study of nine habitual users of oral snuff. Blood pressure, heart rate, and central hemodynamics were measured noninvasively. Plasma concentrations of nicotine, cotinine, norepinephrine, and epinephrine, as well as neuropeptide Y-like immunoreactivity were measured before and after snuff intake during rest and exercise. Snuff intake induced a significant increase in heart rate and blood pressure and a decrease in stroke volume during rest. Hemodynamic changes were unrelated to nicotine or cotinine concentrations. Resting levels of norepinephrine and neuropeptide Y-like immunoreactivity were similar with or without snuff, whereas epinephrine was slightly increased 30 minutes after snuff intake. The exercise-induced increase in norepinephrine and neuropeptide Y-like immunoreactivity did not differ between the days subjects received snuff and the days they received placebo. In contrast, maximum work load was associated with a slight increase in circulating epinephrine after snuff intake. The findings suggest that snuff intake is associated with significant hemodynamic effects during rest but not during exercise. These effects could not be readily explained by activation of the sympathetic nervous system.
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| 3. |
- Lepistö, J, et al.
(författare)
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Effects of homodimeric isoforms of platelet-derived growth factor (PDGF-AA and PDGF-BB) on wound healing in rat.
- 1992
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Ingår i: Journal of Surgical Research. - 0022-4804 .- 1095-8673. ; 53:6, s. 596-601
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor (PDGF) has been suggested to have a significant role in wound healing. The present work was aimed at studying the effects of PDGF-AA and PDGF-BB homodimers on developing granulation tissue in rats. Subcutaneously implanted hollow cylindrical cellulose sponges were used as an inductive matrix for the ingrowth of granulation tissue. Fifty microliters of solutions containing 0, 5, 50, or 500 ng of PDGF-AA or PDGF-BB homodimers was injected daily into the sponges; 7 days after implantation the granulation tissue in the sponge cylinders was analyzed. Five hundred nanograms of PDGF-BB stimulated significantly the accumulation of collagen, indicated by the elevated hydroxyproline content of the sponge (+34%, P < 0.001). Similarly, the amounts of RNA-ribose, nitrogen, hexosamines, and uronic acids were significantly higher, reflecting a PDGF-BB-induced increase in the accumulation of RNA, protein, and glycosaminoglycans. Analyses of wound fluid showed no essential changes in the composition of different cell types after PDGF-BB-treatment. The PDGF-AA-treatment increased significantly the mean amount of RNA but there were no significant changes in other parameters. In vitro both PDGF-AA and PDGF-BB increased significantly the number of rat granulation tissue derived fibroblasts in culture at concentrations of 10 and 30 ng/ml. This proliferative effect resulted in a lowered level of protein synthesis per cell. To conclude, PDGF-BB accelerates granulation tissue formation both in vitro and in vivo, whereas PDGF-AA is effective in vitro but it is clearly less effective in vivo.
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| 4. |
- Lepistö, J, et al.
(författare)
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Stimulation of wound healing by the immunomodulator LS-2616 (Linomide).
- 1994
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Ingår i: World Journal of Surgery. - 0364-2313 .- 1432-2323. ; 18:6, s. 818-20; discussion 821
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Tidskriftsartikel (refereegranskat)abstract
- LS-2616 (Linomide), a quinoline-3-carboxamide, is an immunomodulator that has been suggested to act on macrophage-like cells. Based on a hypothesis that LS-2616 would stimulate macrophages in the wound and affect the healing process, the effects of LS-2616 on developing granulation tissue were evaluated using a wound model in rats. Subcutaneously implanted cylindrical cellulose sponges were used as an inductive matrix for the ingrowth of granulation tissue. LS-2616 was continuously present at a concentration of 1.2 mg/ml in the drinking water either for 7 days before implantation or starting at the implantation of sponges. Seven days after implantation LS-2616 treatment increased the mean amounts of nitrogen and collagen hydroxyproline over the control level [+20% (p < 0.05) and +59% (p < 0.05), respectively]. The effect was less pronounced in the rats receiving LS-2616 in advance [+7% (NS) and +38% (p < 0.05), respectively]. The mean amounts of nucleic acids and proteoglycans tended to decrease in the rats receiving LS-2616 in advance compared to the control rats [-12% to 13% (NS) and -25% (p < 0.05), respectively]. It was concluded that continuous oral administration of LS-2616 enhanced wound repair in the rat. This immunoenhancement of wound healing results in increased accumulation of collagen.
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| 5. |
- Phillips, P.J., et al.
(författare)
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Intracellular analysis of a lymphoblastoid cell line using H-NMR
- 1994
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Ingår i: Animal Cell Technology: Basic & Applied Aspects. - Dordrecht : Springer Verlag (Kluwer). - 9789401043663 - 9789401108485 ; , s. 351-358
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Bokkapitel (refereegranskat)abstract
- A complete analysis of growth and protein production characteristics of a commercially relevant animal cell line has been undertaken. The model cell line was a human lymphoblastoid which produces an IgG antibody against anti-D in blood. The batch growth characteristics of this cell line under different conditions was monitored and analysis of major nutrients and products as well as amino acids in the medium was undertaken. The internal (i.e. intracellular) concentrations of a variety of species in the cell were investigated using H-NMR of cellular extracts. This analysis enabled the quantitative determination of many amino acids, biosynthetic intermediates, secreted products and energetically important intermediates.
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| 6. |
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| 7. |
- Axelsson, B.O.M., et al.
(författare)
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Studies of the main cutting force at and near a cutting edge
- 1993
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Ingår i: European Journal of Wood and Wood Products. - 0018-3768 .- 1436-736X. ; 51:1, s. 43-48
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Tidskriftsartikel (refereegranskat)abstract
- The present work is a study of how various parameters affect the cutting forces at, and near a cutting edge when cutting wood at full speed and with all cutting edges of the tool. Statistical methods from experimental results are used to develop a model
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| 8. |
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| 9. |
- Carlsson, J., et al.
(författare)
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Method for determination of in-hole dynamic force-penetration data from two-point strain measurement on a percussive drill rod
- 1990
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Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - 0148-9062 .- 1879-2073. ; 27:6, s. 553-558
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present investigation is to establish a testing method suited for determination of in-hole dynamic force-penetration data for non-uniform standard percussive drill rod-bit configurations. The method is based on a version of the method of two-point strain measurement, which permits non-uniform rods, i.e. rods with variable characteristic impedance. This version allows normal force and particle velocity to be evaluated at an arbitrary cross-section of a homogenous non-uniform elastic rod from strain measurements performed at two different cross-sections of the same rod. The main problem of this investigation is to assess whether the influence of threads can be considered insignificant. As a part of the study force-penetration relationships have been determined for the penetration of a standard Sandvik Rock Tools button bit into Swedish Bohus granite.
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| 10. |
- Feng, Q P, et al.
(författare)
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Cardiac neuropeptide Y and noradrenaline balance in patients with congestive heart failure.
- 1994
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Ingår i: British heart journal. - 0007-0769. ; 71:3, s. 261-7
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Tidskriftsartikel (refereegranskat)abstract
- To measure plasma concentrations of noradrenaline and neuropeptide Y-like immunoreactivity in relation to cardiac function in patients with congestive heart failure.Retrospective analysis of plasma noradrenaline concentrations and neuropeptide Y-like immunoreactivity in the arterial and coronary circulations, in patients with a high or low ejection fraction (31.3% (1.3%) or 17.7% (1.1%) respectively) and in healthy volunteers.Cardiology department of a university hospital.41 patients with congestive heart failure with various aetiologies. Ten healthy volunteers served as a reference group.Concentrations of noradrenaline measured by high performance liquid chromatography and of neuropeptide Y-like immunoreactivity measured by radioimmunoassay. Cardiac index, pulmonary capillary wedge pressure, pulmonary vascular resistance, and systemic vascular resistance were derived by catheterisation of the right heart. Ejection fraction was measured by radionuclide angiography, cineangiography, or M mode echocardiography.There were pronounced and significant increases in circulating arterial concentrations of neuropeptide Y-like immunoreactivity and noradrenaline in both the high and low ejection fraction groups compared with the healthy subjects. In the patients myocardial release of neuropeptide Y-like immunoreactivity tended to be greater compared with normal subjects, but not significantly so. While normal subjects showed myocardial noradrenaline uptake, patients with congestive heart failure showed significant and progressive myocardial noradrenaline release. Arterial as well as coronary sinus concentrations of neuropeptide Y-like immunoreactivity correlated significantly with plasma noradrenaline concentrations from the respective sites. Plasma noradrenaline concentrations in the artery and coronary sinus were negatively correlated with ejection fraction and cardiac index; no such relations were found for concentrations of neuropeptide Y-like immunoreactivity.Both circulating concentrations of neuropeptide Y-like immunoreactivity and noradrenaline are significantly increased in moderate to severe forms of congestive heart failure. Plasma concentrations of neuropeptide Y-like immunoreactivity correlated with plasma noradrenaline concentrations, but plasma noradrenaline concentrations alone correlated with ejection fraction and cardiac index. Thus plasma noradrenaline concentration seems to be a more sensitive index of cardiac dysfunction than the concentration of neuropeptide Y-like immunoreactivity in congestive heart failure.
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| 11. |
- Germann, Markus W., et al.
(författare)
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Perturbation of DNA hairpins containing the EcoRI recognition site by hairpin loops of varying size and composition : physical (NMR and UV) and enzymatic (EcoRI) studies
- 1990
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Ingår i: Nucleic Acids Research. - : Oxford University Press. - 0305-1048 .- 1362-4962. ; 18:6, s. 1489-1498
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated loop-induced structural perturbation of the stem structure in hairpins d(GAATTCXnGAATTC) (X = A, T and n = 3, 4, 5 and 6) that contain an EcoRI restriction site in close proximity to the hairpin loop. Oligonucleotides containing either a T3 or a A3 loop were not hydrolyzed by the restriction enzyme and also showed only weak binding to EcoRI in the absence of the cofactor Mg2+. In contrast, hairpins with larger loops are hydrolyzed by the enzyme at the scission site next to the loop although the substrate with a A4 loop is significantly more resistant than the oligonucleotide containing a T4 loop. The hairpin structures with 3 loop residues were found to be thermally most stable while larger hairpin loops resulted in structures with lower melting temperatures. The T-loop hairpins are thermally more stable than the hairpins containing the same number of A residues in the loop. As judged from proton NMR spectroscopy and the thermodynamic data, the base pair closest to the hairpin loop did form in all cases studied. The hairpin loops did, however, affect the conformation of the stem structure of the hairpins. From 31P and 1H NMR spectroscopy we conclude that the perturbation of the stem structure is stronger for smaller hairpin loops and that the extent of the perturbation is limited to 2-3 base pairs for hairpins with T3 or A4 loops. Our results demonstrate that hairpin loops modulate the conformation of the stem residues close to the loop and that this in turn reduces the substrate activity for DNA sequence specific proteins.
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| 12. |
- Gustafsson, Petter, 1948-, et al.
(författare)
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STRUCTURE AND REGULATION OF PHOTOSYNTHESIS GENES IN PINUS-SYLVESTRIS (SCOTS PINE) AND PINUS-CONTORTA (LODGEPOLE PINE)
- 1991
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Ingår i: Forest Ecology and Management. - 0378-1127 .- 1872-7042. ; 43:3-4, s. 287-300
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Tidskriftsartikel (refereegranskat)abstract
- The structure and regulation of one nuclear and one chloroplast gene was studied in Pinus sylvestris (Scots pine) and Pinus contorta (lodgepole pine). cDNA copies of the nuclear located cab genes of Pinus sylvestris, coding for the light-harvesting chlorophyll a/b-binding proteins of photosystem II (LHC-II), were cloned. cab-II genes coding for both types of LHC-II polypeptides, Types 1 and 2, were found. An analysis of the DNA sequences of several different cab-II cDNAs shows that they have a high bias for the nucleotides G and C at the third base positions of the codons, making them more similar to monocot than to dicot genes. Two of the three genes were found to be located within CpG islands. The cab-II genes were found to be expressed in dark-grown seedlings in contrast to what has been found for most angiosperms. The chloroplast genomes of conifers were shown to lack the inverted repeat organization normally found in higher plants, mosses and green algae. The psbA gene, located in the chloroplast genome and coding for the D1 polypeptide in the reaction center of photosystem II, was found to be tandemly duplicated in P. contorta. Cloning and sequence analysis of the two psbA genes and the surrounding regions showed that the duplicated segment is 1.97 kb long and that it ends 19 bp downstream from the psbA stop codon. The corresponding locus of P. sylvestris, which lacks the duplication, was cloned and characterized. A comparison with P. contorta indicates how the duplication/insertion event has occurred. A comparison of third codon position between P. contorta psbA and that of other plants indicated an almost equidistant evolutionary relationship between P. contorta, spinach (or barley) and Marchantia polymorpha.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- HOVI, M, et al.
(författare)
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LEK CENTER ATTRACTS BLACK GROUSE FEMALES
- 1994
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Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 258:1353, s. 303-305
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Tidskriftsartikel (refereegranskat)
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| 17. |
- Håkansson, H., et al.
(författare)
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In vivo and in vitro toxicity of fractionated fish lipids, with particular regard to their content of chlorinated organic compounds
- 1991
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Ingår i: Pharmacology and Toxicology. - : Wiley. - 0901-9928 .- 1600-0773. ; 69:6, s. 459-471
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Tidskriftsartikel (refereegranskat)abstract
- Six different lipid matrices (the intact lipid (IL), four lipid fractions with different polarity, and the free fatty acids (FFAs) obtained by hydrolysis of the triacylglycerol (TAG) containing fraction) were obtained from salmon (Salmo salar) and eel (Anguilla anguilla), each collected at a contaminated and a comparatively uncontaminated catch site along the coast of Scandinavia. The lipid matrices were studied in toxicological test systems representing various biological functions of different organ systems from several species and trophic levels. The results were evaluated with particular respect to the concentrations of extractable organically bound chlorine (EOCl) in the matrices tested. In some test systems, the specimens with a higher EOCl concentration appeared to be more toxic. For example, the TAG containing fraction (F2) from Idefjord eel, having a higher EOCl content than F2 from Oslofjord eel, reduced the number and hatchability of eggs laid by zebrafish. Both IL and F2 of Idefjord eel increased mortality and reduced the oxygen/nitrogen-ratio in blue mussels. Non-polar compounds (F1) from Bothnian Sea salmon induced 7-ethoxyresurofin O-deethylase (EROD) activity in rainbow trout hepatocytes, whereas F1 from Senja salmon did not. F1 from Bothnian Sea salmon also reduced the number of T-cells in foetal mouse thymus anlagen in vitro compared with the cell number in anlagen exposed to F1 from Senja salmon. A positive correlation between EOCl concentration and test response was found for EROD activity in rainbow trout hepatocytes and for ATP-leakage in Erlich ascites tumour cells when testing the phospolipid containing fraction (F4). However, in most test systems the fish oils, irrespective of EOCl content, were of low toxicity, and the observed effects need to be verified in future studies.
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| 18. |
- Lundberg, Bengt, et al.
(författare)
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Analysis of elastic waves in non-uniform rods from two-point strain measurement
- 1990
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Ingår i: Journal of Sound and Vibration. - 0022-460X .- 1095-8568. ; 137:3, s. 483-493
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Tidskriftsartikel (refereegranskat)abstract
- A method is established which permits evaluation of the histories of normal force and particle velocity at an arbitrary cross-section E of a non-uniform linearly-elastic rod from measured strain histories at two different cross-sections, A and B. Other quantities at E, such as stress, strain, displacement, acceleration and power transmission, can be determined in terms of the evaluated normal force and particle velocity. The method is an extension of that developed by Lundberg and Henchoz for uniform rods. Theoretical results, based on one-dimensional elastic wave theory, are provided for the general case as well as for cases of piecewise constant characteritic impedance. Experimental tests with different configurations of non-uniform rods and strain gauges show that the normal force histories determined at E with the present method (from measured strains at A and B) agree well with those obtained through direct strain measurement at E.
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| 19. |
- Lundberg, Peter, et al.
(författare)
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NMR studies of erythrocytes immobilized in agarose and alginate gels
- 1992
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Ingår i: Magnetic Resonance in Medicine. - : John Wiley & Sons. - 0740-3194 .- 1522-2594. ; 25:2, s. 273-288
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Tidskriftsartikel (refereegranskat)abstract
- 31P and 13C NMR were used to study the energy metabolism in perfused, human erythrocytes. The erythrocytes were immobilized in agarose threads, Ca- or Ba-alginate beads, and Ba-alginate-coated agarose threads. Erythrocytes were easily washed out from the agarose threads, but not from alginate-containing gels. Various small molecules, such as hypophosphite, dimethyl methylphosphonate, and methylphosphonate, were taken up from the perfusion medium in a normal manner. In addition, the 2,3-bisphosphoglycerate (2,3-DPG) chemical shifts were sensitive to the oxygen partial pressure suggesting that O2 molecules were diffusing through the gel and modifying the binding of 2,3-DPG to hemoglobin. A combination of inosine and pyruvate stimulated the synthesis of 2,3-DPG, but only if inorganic phosphate was present in the perfusion medium. Inosine only resulted in a dramatic rise in the intracellular sugarphosphate concentrations. Furthermore, [2-13C]glucose was converted to [2-13C]lactate by immobilized cells at a rate which was comparable to that in a control suspension. In summary, immobilization in Ba-alginate-coated agarose threads was an efficient way of trapping human erythrocytes for whole cell NMR investigations.
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| 20. |
- Lundberg, Peter, et al.
(författare)
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Nuclear magnetic resonance studies of cellular metabolism
- 1990
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Ingår i: Analytical Biochemistry. - 0003-2697 .- 1096-0309. ; 191:2, s. 193-222
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear magnetic resonance (NMR) spectroscopy was described in 1946 (1,2), initially as a method that had appeal only for nuclear physicists who used it to accurately determine nuclear magnetic moments. Thissituation changed rapidly, however, when it was demonstrated that the NMR frequency for the same nucleus in different chemical compounds was different (3). For example, two separate signals are observed in a 14N NMR spectrum of a solution of NH,NO,, representing the NH: and NO; ions, respectively (4). Since individual atoms within one molecule also give rise to resolved signals (5) it became clear that the NMR technique held great analytical potential, in particular since the spectra can be recorded in such a way that the area under a signal is directly proportional to its concentration. Such phenomena and various theoretical aspects of NMR are currently quite well understood (6,7). Because of these features NMR has become the foremost spectroscopic method for the analysis of all sorts of chemical compounds.
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| 21. |
- Tolosa, A J G, et al.
(författare)
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Effekter av polybromerade difenyletrar på sötvattenlevande evertebrater
- 1993
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Polybromerade difenyletrar (PBDE) är en typ av persistenta, lipofila substanser som bl a ingår i flamskyddsmedel, jordbrukskemikalier och bensintillsatser. Stora mängder av dessa ämnen kommer så småningom ut i naturen men omfattningen och effekter är ännu föga kända. PBDE är huvudbeståndsdel i den tekniska blandningen Bromkal 70. För att testa kroniska effekter av PBDE på sötvattensevertebrater användes statiska vattensystem bestående av kärl med sediment som kontaminerats med Bromkal 70. I systemen hölls i olika försök individer av arterna Asellus aquaticus (gråsugga) och Gammarus pulex (märlkräfta). Studerade parametrar var överlevnad, reproduktionsframgång och subletala effekter. Dessutom undersöktes eventuella synergistiska effekter på kvicksilverupptag hos Chironomus riparius (fjädermygglarv). Försöken där reproduktion samt överlevnad av adulta och juvenila märlkräftor studerades (koncentration Bromkal 70: 10, 150, 500 och 1000 ppm våtvikt) visade inte på några statistiska skillnader mellan de olika exponeringarna. Stora svårigheter att tolka resultaten förelåg dock p g a flera metodiska problem samt stor dödlighet i kontrollen. I försöket där sedimentet kontaminerats både med Bromkal 70 (0,01, 1 och 100 ppm våtvikt) och radioaktivt kvicksilver framkom att storleken på upptaget av kvicksilver hos Chironomus var beroende av halten Bromkal 70 i sedimentet samt exponeringstiden.
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| 22. |
- Vogel, Hans J, et al.
(författare)
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Uptake, metabolism, and storage of phosphate and nitrogen in plant cells; an NMR perspective
- 1990
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Ingår i: NMR applications in biopolymers. - Boston, MA : Plenum Press, New York, USA. - 9781468458701 - 9781468458688 ; , s. 329-348
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Bokkapitel (refereegranskat)abstract
- A number of Nuclear Magnetic Resonance (NMR) Spectroscopy techniques can be used to study pH regulation and various aspects of nutrient metabolism in plant material. In this study phosphorus-31 NMR has been used to determine the energy state (ATP) and the intracellular cytoplasmic and vacuolar pH of cultured plant cells and algae. For the algae it was found that the chemical shift of the terminal polyphosphate resonance provided a good monitor of the vacuolar pH which was estimated at pH 5.5. A cytoplasmic pH of 7.2 was determined from the chemical shifts of the Pi and glucose-6-phosphate resonances. Phosphate uptake could also be followed by 31P NMR and these studies showed that Pi was stored as polyphosphates in algae, but as vacuolar Pi in certain higher plants such as Catharanthus roseus and Nicotiana tabacum.
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