| 1. |
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| 2. |
- Anderbrant, Olle, et al.
(författare)
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Field response of the pine sawfly Neodiprion sertifer to the pheromone (2S, 3S, 7S)‐diprionyl acetate and its stereoisomers
- 1992
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Ingår i: Entomologia Experimentalis et Applicata. - : Wiley. - 0013-8703. ; 62:2, s. 169-181
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Tidskriftsartikel (refereegranskat)abstract
- All eight optical isomers of 3,7‐dimethyl‐2‐pentadecanyl acetate (diprionyl acetate), of high optical purity (>97.4%), were tested for a behavioural activity on male pine sawflies, Neodiprion sertifer (Geoffr.) (Hymenoptera: Diprionidae), in northern Europe. Males were strongly attracted to (2S, 3S, 7S)‐diprionyl acetate. Addition of more than 0.1% of the (2S, 3R, 7R)‐isomer reduced the catch and above 2% the attraction was completely inhibited. Contrary to what has been reported for North American and Japanese populations, so significant synergistic effect of small amounts of the (2S, 3R, 7R)‐isomer could be demonstrated. The effects of addition of the other six optical isomers alone or in combinations, were also studied, but none was found to be a synergist. The (2S, 3R, 7S)‐isomer had a weak inhibitory effect, and completely inhibited the attraction to the (2S, 3S, 7S)‐isomer when applied in about equal amounts as the attractant. In some cases a reduction in catch was noted when other isomers were tested, but this could be attributed to the very small amounts of the inhibitory (2S, 3R, 7R)‐isomer present in these isomers. 1992 The Netherlands Entomological Society
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| 3. |
- Magnusson, Yvonne, 1957, et al.
(författare)
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Functional analysis of rabbit anti-peptide antibodies which mimic autoantibodies against the beta 1-adrenergic receptor in patients with idiopathic dilated cardiomyopathy.
- 1991
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Ingår i: Journal of autoimmunity. - 0896-8411. ; 4:6, s. 893-905
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Tidskriftsartikel (refereegranskat)abstract
- A synthetic peptide corresponding to the second extracellular loop of the beta 1-adrenergic receptor was used as an antigen for antibody production in three rabbits. Antibodies of high titers were obtained in all rabbits. Only one rabbit yielded antibodies which decreased radioligand binding on the receptor in a similar way to that described for autoantibodies in patients with dilated cardiomyopathy. These antibodies recognized the receptor protein in immunoblots. Epitope mapping indicated that the N-terminal sequence of the loop used as antigen was the target of the major antigen fraction. Incubation of antibodies with C6 glioma cell membranes or inner membranes of E. coli, which express the human beta 1-adrenergic receptor, resulted in a decrease in number of radioligand binding sites. This decrease was dependent on the concentration of antibody and of Mg++ ions. It was not affected by the GTP analog GppNHp or the beta 1 subtype-specific antagonist metoprolol. The agonist, isoproterenol, also induced a decrease but the effects of antibody and agonist were not additive. These results suggest that the antibodies induce a Mg(++)-dependent, 'active', labile conformation of the receptor, independent from coupling to the GTP regulatory protein, but similar to that induced by the agonist isoproterenol. This interpretation was corroborated by the beta 1-adrenergic receptor agonist-like effect of the antibodies on cardiomyocytes in culture.
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| 4. |
- Ruediger, R, et al.
(författare)
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Identification of binding sites on the regulatory A subunit of protein phosphatase 2A for the catalytic C subunit and for tumor antigens of simian virus 40 and polyomavirus.
- 1992
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 12:11, s. 4872-82
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Tidskriftsartikel (refereegranskat)abstract
- Protein phosphatase 2A is composed of three subunits: the catalytic subunit C and two regulatory subunits, A and B. The A subunit consists of 15 nonidentical repeats and has a rodlike shape. It is associated with the B and C subunits as well as with the simian virus 40 small T, polyomavirus small T, and polyomavirus medium T tumor antigens. We determined the binding sites on subunit A for subunit C and tumor antigens by site-directed mutagenesis of A. Twenty-four N- and C-terminal truncations and internal deletions of A were assayed by coimmunoprecipitation for their ability to bind C and tumor antigens. It was found that C binds to repeats 11 to 15 at the C terminus of A, whereas T antigens bind to overlapping but distinct regions of the N terminus. Simian virus 40 small T binds to repeats 3 to 6, and polyomavirus small T and medium T bind to repeats 2 to 8. The data suggest cooperativity between C and T antigens in binding to A. This is most apparent for medium T antigen, which can only bind to those A subunit molecules that provide the entire binding region for the C subunit. We infer from our results that B also binds to N-terminal repeats. A model of the small T/medium T/B-A-C complexes is presented.
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| 5. |
- Bergqvist, A, et al.
(författare)
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Loss of DNA-binding and new transcriptional trans-activation function in polyomavirus large T-antigen with mutation of zinc finger motif.
- 1990
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Ingår i: Nucleic Acids Research. - 0305-1048 .- 1362-4962. ; 18:9, s. 2715-20
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Tidskriftsartikel (refereegranskat)abstract
- A putative zinc finger in polyomavirus large T-antigen was investigated. We were unable to demonstrate unequivocally a requirement for zinc in specific DNA-binding using the chelating agent 1, 10-phenanthroline. An involvement of the putative zinc finger in specific DNA-binding was nevertheless suggested by the properties of a mutant protein with a cys----ser replacement in the finger motif. Probably as a result of the defective DNA-binding, the mutant protein had lost its activity in initiation of viral DNA-replication and in negative regulation of viral early transcription. However, the trans-activation of the viral late promoter was normal. The analysis also revealed a previously unrecognized activity of large T-antigen. The mutant protein trans-activated the viral early promoter. In the wild-type protein this activity is probably concealed by the separate, negative regulatory function.
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| 6. |
- Bondeson, K, et al.
(författare)
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Lactose repressor-operator DNA interactions : kinetic analysis by a surface plasmon resonance biosensor.
- 1993
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Ingår i: Analytical Biochemistry. - 0003-2697 .- 1096-0309. ; 214:1, s. 245-51
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Tidskriftsartikel (refereegranskat)abstract
- Lactose repressor binding to operator DNA and subsequent dissociation of the complex was monitored continuously by a biosensor, measuring surface plasmon resonance. In this analysis a synthetic, double-stranded oligonucleotide containing the operator site was immobilized on the sensor surface and repressor protein was passed over the surface. The formation of the repressor-operator complex was specific and could be inhibited by isopropyl-beta-D-thiogalactopyranoside inducer. From the association curve, the apparent kass was determined to be 1.8 x 10(6) M-1 s-1. Dissociation of the complex was, for the first time for the lac repressor, determined as an uncatalyzed reaction and the kdiss was determined to be 3.4 x 10(-4) s-1. As a reference, the repressor-operator interaction was analyzed by electrophoretic mobility shift assay under similar reaction conditions. With this method the equilibrium binding constant was calculated to be 2.4 (+/- 0.2) x 10(8) M-1. The corresponding value calculated from biosensor data was 5.1 x 10(9) M-1.
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| 7. |
- De Château, M, et al.
(författare)
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On the interaction between protein L and immunoglobulins of various mammalian species
- 1993
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 37:4, s. 399-405
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Tidskriftsartikel (refereegranskat)abstract
- Protein L, a cell wall molecule of certain strains of the anaerobic bacterial species Peptostreptococcus magnus, shows high affinity for human immunoglobulin (Ig) light chains. In the present study protein L was tested against a panel of human myeloma proteins of the IgG, IgM, IgA and IgE classes, and strong binding was seen with antibodies carrying kappa light chains. A high degree of specificity for Ig was demonstrated in binding experiments with human plasma proteins. Apart from human Ig, strong protein L-binding activity was also detected in the serum of 12 out of 23 tested additional mammalian species, including other primates and rodents. Subsequent analysis with purified Ig samples demonstrated the binding of protein L to Ig of important laboratory animal species such as the mouse, the rat and the rabbit. The affinity constants for the interactions between protein L and polyclonal IgG of these species were 2.6 x 10(9), 3.9 x 10(8) and 7.4 x 10(7), respectively. In non-human species, the binding of protein L was also found to be mediated through Ig light chains, and the results demonstrate the potential value of protein L as an immunochemical tool.
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| 8. |
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| 9. |
- Eng, H, et al.
(författare)
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Beta 2-adrenergic receptor antibodies in myasthenia gravis.
- 1992
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Ingår i: Journal of autoimmunity. - 0896-8411. ; 5:2, s. 213-27
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Tidskriftsartikel (refereegranskat)abstract
- Although autoantibodies against the nicotinic acetylcholine receptor are the characteristic feature of the autoimmune disease myasthenia gravis (MG), no strong correlation is found between the autoantibody titer and the degree of clinical severity. Numerous studies have attempted to detect the presence of other autoantibody populations that might have a role in the pathology of the disease. We report, for the first time, that 18% of the MG patients we screened have antibodies in their serum to a peptide corresponding to the second extracellular loop of the human beta 2-adrenergic receptor (residues 172-197). Affinity purified antibodies to the beta 2-adrenergic receptor peptide 172-197 reacted with the human beta 2-adrenergic receptor protein obtained from transfected E. coli cell membrane extracts, but did not cross-react with the human AChR. Sufficient material was obtained from nine MG patients and it was found that the gamma globulin fraction from these patients immunoprecipitated the receptor, and that affinity purified IgG to peptide 172-197 competed for receptor binding with the beta-antagonist iodo-cyanopindolol. Using truncated peptides or amino acid modification procedures, no immunodominant B-cell epitope could be detected within region 172-197. Thus, a subpopulation of MG patients possesses anti-beta 2-adrenergic receptor antibodies which are a distinct set of autoantibodies with possible pharmacological activity.
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| 10. |
- Eriksson, Barbro, et al.
(författare)
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Neuroendocrine pancreatic tumours : clinical presentation, biochemical and histopathological findings in 84 patients
- 1990
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 228:2, s. 103-113
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Tidskriftsartikel (refereegranskat)abstract
- A prospective study has been performed on 84 patients with endocrine pancreatic tumours evaluated at the Medical Department in Uppsala. Available information concerning the patients' presenting symptoms, age at diagnosis, clinical syndrome, tumour location, location of metastases, diagnostic radiology, biochemical and histopathological findings has been analysed. Our results indicate that most patients initially show rather vague and non-specific symptoms, with dyspepsia and pain being the most frequent presenting features. The median delay between appearance of the first symptom and diagnosis was 2 years; the delay was 3 5 months in sporadic cases and 14.5 months in familial cases. In spite of improvements in diagnostic methods, the median age at diagnosis (53 years) has not been reduced, and most patients are encountered when the tumour has reached an advanced stage. There is a need for a method of screening patients with still uncharacteristic abdominalsymptoms for a neuroendocrine tumour. The presence of elevated levels of plasma chromogranin in all patients with a proven tumour suggests that such possibilities exist, and the use of this biochemical marker in the future might reduce the age at diagnosis and thus improve the likelihood of cure and survival of patients with endocrine pancreatic tumours.
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