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C Gustafsson

Publications and source records attributed to C Gustafsson.

18 recordsLinked to original sources
PubMed1996

Identification of new RNA modifying enzymes by iterative genome search using known modifying enzymes as probes.

The complete nucleotide sequences of the Haemophilus influenzae and Mycoplasma genitalium genomes and the partially sequenced Escherichia coli chromosome were analyzed to identify open reading frames (ORFs) likely to encode RNA modifying enzymes. The protein sequences of known RNA modifying enzymes from three families--m5U methyltransferases, psi synthases and 2'-O methyltransferases--were used as probes to search sequence databases for homologs. ORFs identified as homologous to the initial probes were retrieved and used as new probes against the databases in an iterative manner until no more homologous ORFs could be identified. Using this approach, we have identified two new m5U methyltransferases, seven new psi synthases and four new 2'-O methyltransferases in E. coli. Many of the ORFs found in E.coli have direct genetic counterparts (orthologs) in one or both of H.influenzae and M.genitalium. Since there is a near-complete knowledge of RNA modifications in E.coli, functional activities of the proteins encoded by the identified ORFs were proposed based on the level of conservation of the ORFs and the modified nucleotides.

Amino Acid Sequence↗
PubMed1994

Production of large amounts of recombinant interleukins by cDNA transfected mouse myeloma cells cultured in dialysis tubing.

Studies of interleukin function often require large quantities of these highly expensive substances. The available interleukins are generally recombinant proteins produced in bacteria or yeast and, less commonly, interleukins produced by mammalian cells, which provide appropriate glycosylation and other post-translational modifications. Due to differences in biosynthesis, difficulties in production and purification the quality of the interleukin preparations may vary. We have taken advantage of the recently developed constitutively interleukin-secreting mouse myeloma cell lines and the dialysis tubing culture technique, which permit cells to be grown at high densities, in order to establish a method for the production of large amounts of recombinant murine IL-2 and IL-4. We show that these interleukins can be produced at low cost and in concentrations 20-30-fold higher than in conventional culture flasks. A single dialysis tubing culture will produce more than 10(6) U of interleukin which may be compared with the available commercial preparations containing between 10- and a 100-fold less per vial. The IL-2 and IL-4 produced in this manner are biologically active molecules as demonstrated by the strong proliferative response of clonal T cells and the isotype-switching effect in LPS-stimulated splenic B cell cultures. The dialysis tubing culture technique is a simple and highly cost-effective means of generating large quantities of biologically active interleukins and is especially suitable for research laboratories interested in functional studies of these proteins.

Animals↗
PubMed1994

Validation of four scales for the acute stage of stroke.

OBJECTIVES: To validate whether a simplified scale for the acute stage of stroke--the Scandinavian Stroke Supervision scale--is sufficient for monitoring symptom progression of prognostic importance. DESIGN: The capacity of the scale was compared to that of the Mathew, Toronto and Fugl-Meyer stroke scales and the Barthel ADL index. SETTING: The stroke unit of Danderyd Hospital, which cares for a defined population. SUBJECTS: Fifty noncomatose patients with objectively recorded symptoms at entry were examined over a period of 5 days by one physician (250 ratings/scale). The last 10 patients were also investigated by another doctor in the same manner (50 ratings/scale) and by nurses (50 ratings) the Scandinavian scale only. The amount of time required by each scale was tested in another 10 patients by two nurses (100 ratings/scale). INTERVENTIONS: Routine investigation and treatment. MAIN OUTCOME MEASURES: The reliability, validity, time requirement and correlation of the scales were evaluated, as was their ability to reveal progress of symptoms. RESULTS: All scales were highly significantly correlated. The interobserver agreement was excellent between the physicians but not as good between the physician and the nurses. The prediction of the outcome at discharge and after 3 months was very satisfactory for all of the scales with regard to the whole groups of patients, but none of them could predict the outcome for an individual with certainty. The Scandinavian Stroke Supervision scale was least time consuming, and had the fewest uncertainties expressed by the testers. This scale recorded the progression of slightly fewer symptoms, but did record those with a more serious impact on patient outcome. CONCLUSION: The time-saving, simplified Scandinavian scale was as reliable and as valid as the other scales, and detected deterioration that was important for patient outcome as satisfactorily as the other scales.

Acute Disease↗
PubMed1993

Quantitative sequence-activity models (QSAM)--tools for sequence design.

Models have been developed that allow the biological activity of a DNA segment to be altered in a desired direction. Partial least squares projections to latent structures (PLS) was used to establish a quantitative model between a numerical description of 68 bp fragments of 25 E.coli promoters and their corresponding quantitative measure of in vivo strength. This quantitative sequence-activity model (QSAM) was used to generate two 68 bp fragments predicted to be more potent promoters than any of those on which the model originally was based. The optimized structures were experimentally verified to be strong promoters in vivo.

Base Composition↗
PubMed1993

The tRNA-(m5U54)-methyltransferase of Escherichia coli is present in two forms in vivo, one of which is present as bound to tRNA and to a 3'-end fragment of 16 S rRNA.

The enzyme tRNA-(m5U54)-methyltransferase (EC 2.1.1.35) of Escherichia coli catalyzes the transfer of a methyl group from S-adenosyl-L-methionine to uridine in position 54 of the T psi-loop of all E. coli tRNA species, forming 5-methyluridine (m5U). In vivo, this enzyme is present both as a native polypeptide of 42 kDa and as a TrmA.RNA complex. The TrmA.RNA complex is not dissociated during strong denaturing conditions such as boiling in 8 M urea or 6 M guanidine HCl, consisting with that the RNA is covalently bound to the protein. After sequencing and Southern blot analyses, the RNA was identified to be a subset of undermodified tRNA species as well as the 3' terminus of 16 S rRNA. However, the complex is not associated with the ribosome and the covalently bound RNA does not affect the tRNA methylating activity of the enzyme.

Base Sequence↗
PubMed1993

Effects of acute exercise on insulin and non-insulin-dependent glucose uptake in normal and moderately obese women.

OBJECTIVES: To investigate the effectiveness of exercise on the regulation of insulin sensitivity. METHODS: Eleven premenopausal women, with body fat mass from the normal range to moderate obesity, were examined with glucose clamp at 10 mmol/L glucose concentration to determine insulin-dependent and non-insulin-dependent (after somatostatin inhibition of endogenous insulin production) glucose uptake (= IDGU and NIDGU respectively) before and 24 hrs after a glycogen-decreasing exercise. RESULTS: IDGU, but not NIDGU, increased after exercise. The degree of increase of IDGU after exercise showed negative correlations with body mass index (borderline, significance), the waist to hip circumference ratio, fasting free testosterone and free fatty acid concentrations, as well as diastolic blood pressure (borderline significance), and a positive relationship to sex hormone binding globulin concentration and IDGU before exercise. CONCLUSION: It is concluded that only IDGU contributes to the augmentation of insulin sensitivity after a glycogen-decreasing exercise in women. Additionally, the increase of IDGU is less in abdominal obesity, and negatively dependent on free fatty acid concentrations, hyperandrogenism and hyperinsulinaemia, all putative pathogenetic factors for insulin resistance.

Adult↗
PubMed1992

Cost effectiveness of primary stroke prevention in atrial fibrillation: Swedish national perspective.

OBJECTIVE: To assess the potential effects of primary prevention with anticoagulants or aspirin in atrial fibrillation on Swedish population. DESIGN: Analysis of cost effectiveness based on the following assumptions: about 83,000 people have atrial fibrillation in Sweden, of whom 22,000 would be potential candidates for treatment with anticoagulants and 55,000 for aspirin treatment; the annual 5% stroke rate is reduced by 64% (with anticoagulants) and 25% (with aspirin); incidence of intracranial haemorrhage of 0.3%, 1.3%, or 2.0% per year; direct and indirect costs of a stroke of Kr180,000 and Kr90,000; estimated annual cost of treatment is Kr5030 for anticoagulants and Kr100 for aspirin. SETTING: Total Swedish population. MAIN OUTCOME MEASURES: Direct and indirect costs of stroke saved, number of strokes prevented, and cost of preventive treatment. RESULTS: Depending on the rate of haemorrhagic complications 34 to 83 patients would need to be treated annually with anticoagulants to prevent one stroke; 83 patients would need to be treated with aspirin. Giving anticoagulant treatment only would reduce costs by Kr60 million if the incidence of intracranial haemorrhage were 0.3% but would imply a net expense if the complication rate exceeded 1.3%. The total savings from giving anticoagulant (22,000 patients) and aspirin (55,000 patients) treatment would be Kr175 million per year corresponding to 2 million pounds per million inhabitants each year. CONCLUSIONS: Treatment with anticoagulants and, if contraindications exist, with aspirin is cost effective provided that the risk of serious haemorrhage complications due to anticoagulants is kept low.

Aged↗
PubMed1992

The gene for a tRNA modifying enzyme, m5U54-methyltransferase, is essential for viability in Escherichia coli.

One of the most abundant modified nucleosides in tRNA is 5-methyluridine (m5U or rT, ribothymidine). The enzyme tRNA(m5U54)methyltransferase [S-adenosyl-L-methionine:tRNA (uracil-5-)-methyltransferase, EC 2.1.1.35] (the trmA gene product) catalyzes S-adenosylmethionine-dependent methylation of the uracil in position 54 (T psi C loop) in all Escherichia coli tRNAs to form m5U. Hitherto no modified nucleoside in tRNA has been shown to be essential for growth, although their importance in fine tuning the function of tRNA is well established. In this paper, we show that the structural gene trmA is essential for viability, although the known catalytic activity of the tRNA(m5U54)methyltransferase is not.

Bacterial Proteins↗
PubMed1992

Echocardiographic findings and the increased risk of stroke in nonvalvular atrial fibrillation.

We studied whether cardiac abnormalities contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation (NVAF). M-mode and 2D echocardiography were performed in four age- and gender-matched groups: 20 stroke patients with NVAF, 20 patients with NVAF who had not suffered a previous stroke, 20 stroke patients with sinus rhythm, and 40 healthy controls. Their mean age was 77 years. The two groups with atrial fibrillation differed from healthy controls in that they had more 2D-echocardiographic findings of severe left-ventricular-wall-motion abnormalities (p < 0.05) and tended more often to have enlarged left ventricles, and hypertrophic and congestive cardiomyopathy. Left atrial diameter was 47 mm compared to 41 and 39 mm in the two groups with sinus rhythm (p < 0.001). Intracardiac thrombi were only found in the two atrial-fibrillation groups (with stroke: 15% without stroke: 5%). Aortic sclerosis was common in all groups (30-60%), as was mitral annulus calcification (10-20%). The only significant difference between the two atrial-fibrillation groups was a higher frequency of earlier ischemic heart disease in the stroke group. Both atrial-fibrillation groups had cardiac abnormalities predisposing for embolic as well as thrombotic stroke.

Aged↗
PubMed1991

Pathogenetic mechanism of stroke in non-valvular atrial fibrillation: follow-up of stroke patients with and without atrial fibrillation.

Stroke patients with brain infarction and non-valvular atrial fibrillation (NVAF, n = 88) or sinus rhythm (SR, n = 188), treated at a population-based stroke unit, were studied for 5 years. Within 1 month, 13% of NVAF and 2% of SR patients (P less than 0.01) had either a stroke recurrence or systemic embolism. After 5 years, the corresponding figures were 26 and 25%, respectively. The 1-month and 5-year mortality values were 35 and 78% in the NVAF group vs. 7 and 52% in the SR group (P less than 0.01). Age, ischaemic heart disease and function group on arrival at the hospital were independent risk factors for death. The main cause of death was ischaemic heart disease in the NVAF group, and complications to the initial stroke or a stroke recurrence in the SR group. Thus a higher risk of death, stroke recurrence and peripheral embolism was evident only during the first month after stroke.

Aged↗
PubMed1991

The trmA promoter has regulatory features and sequence elements in common with the rRNA P1 promoter family of Escherichia coli.

The tRNA(m5U54)methyltransferase, whose structural gene is designated trmA, catalyzes the formation of 5-methyluridine in position 54 of all tRNA species in Escherichia coli. The synthesis of this enzyme has previously been shown to be both growth rate dependent and stringently regulated, suggesting regulatory features similar to those of rRNA. We have determined the complete nucleotide sequence of the trmA operon in E. coli and the sequence of the trmA promoter region in Salmonella typhimurium and also analyzed the transcriptional regulation of the gene. The trmA and the btuB (encoding the vitamin B12 outer membrane receptor protein) promoters are divergent promoters separated by 102 bp between the transcriptional start sites. The trmA promoters of both E. coli and S. typhimurium share promoter elements with the rRNA P1 promoter. The sequence downstream from the -10 region of the trmA promoter is homologous to the discriminatory region found in stringently regulated promoters. Next to and upstream from the -10 region is a sequence, TCCC, in the trmA promoter that is present in all of the seven rRNA P1 promoters and in some tRNA promoters but not in any other sigma 70 promoter. However, a similar motif is also found in promoters transcribed by the heat shock sigma factor sigma 32. The trmA gene is transcribed as a monocistronic operon, and the 3' end of the transcript is shown to be located downstream from a dyad symmetry region not followed by a poly(U) stretch. Using a trmA-cat operon fusion, we show that the growth rate-dependent regulation of trmA resembles that of rRNA and operates at the level of transcription.

Amino Acid Sequence↗
PubMed1991

Mutations in a herpes simplex virus type 1 origin that inhibit interaction with origin-binding protein also inhibit DNA replication.

The herpes simplex virus type 1 genome contains three origins of replication: OriL and a diploid OriS. The origin-binding protein, the product of the UL9 gene, interacts with two sites within OriS, box I and box II. A third site, box III, which is homologous to boxes I and II, may also be a binding site for the origin-binding protein. Mutations in these three sites significantly reduce OriS-directed plasmid replication measured in transient replication assays. The reduction in replication efficiency of the mutants correlates well with the decrease in the ability to bind to the origin-binding protein, as determined by Elias et al. (P. Elias, C. M. Gustafsson, and O. Hammarsten, J. Biol. Chem. 265: 17167-17173, 1990). The effect of multiple mutations in boxes I, II, and III on plasmid replication suggests that there are multiple binding sites in OriS for the origin-binding protein. These studies indicate that proper interaction of the origin-binding protein with the OriS sequence is essential for OriS-directed DNA replication.

Animals↗
PubMed1990

Coagulation factors and the increased risk of stroke in nonvalvular atrial fibrillation.

We studied whether hemostatic abnormalities contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation. Hemostatic function was studied in four age-matched groups: 20 patients with nonvalvular atrial fibrillation and a previous ischemic stroke, 20 patients with nonvalvular atrial fibrillation without a previous stroke, 20 stroke patients with sinus rhythm, and 40 healthy controls. Both groups with nonvalvular atrial fibrillation had significantly higher concentrations of von Willebrand factor, factor VIII:C, fibrinogen, D-dimer (a fibrinolytic product), beta-thromboglobulin, and platelet factor 4; a significantly higher fibrinogen/antithrombin ratio; and significantly higher spontaneous amidolytic activity than the healthy controls. Prekallikrein levels were significantly lower in both groups with nonvalvular atrial fibrillation. Stroke patients with sinus rhythm had normal hemostatic function, normal concentrations of platelet-related factors, and a slightly increased concentration of fibrinopeptide A compared with the healthy controls. Both groups with nonvalvular atrial fibrillation differed from the stroke patients with sinus rhythm as they did from the healthy controls. No difference in hemostatic function was seen between the nonvalvular atrial fibrillation patients with and without a previous ischemic stroke. Thus, alterations in hemostatic function may contribute to the increased risk of stroke in patients with nonvalvular atrial fibrillation.

Acute-Phase Reaction↗
PubMedDate not supplied

Non-rheumatic atrial fibrillation as a risk factor for stroke.

The association between non-rheumatic atrial fibrillation (AF) and stroke has been studied in 402 patients consecutively admitted to a stroke unit. Brain infarction patients with sinus rhythm (n = 196) and non-rheumatic AF (n = 92) were further compared. Some findings supported an embolic origin of the stroke: half of the deceased AF patients (n = 24) at autopsy either had left atrial thrombosis or arterial embolism compared to none of the ten with sinus rhythm. Patients with AF also had a higher mortality and more severe brain lesions, findings compatible with a sudden occlusion of blood flow. However, these differences might also be explained by an atherothrombotic occlusion with impaired autoregulation in the ischaemic region in conjunction with heart failure, which was more common in the AF patients. Other findings supporting an atherothrombotic mechanism were: the prevalence of AF was higher (19-29%) in all kinds of stroke, including haemorrhage, than in age-matched controls (3-9%). Also patients with previous AF and no present embolic source resembled the whole AF group and differed from patients with sinus rhythm. Thus embolism is a plausible cause of stroke in many AF patients, whereas an atherothrombotic origin is more likely in others. Characteristics identifying the mechanism in an individual case were not found.

Aged↗