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M Göransson

Publications and source records attributed to M Göransson.

At least 19 recordsLinked to original sources
PubMed1994

How much can data on days with heavy drinking decrease the underestimation of true alcohol consumption?

An adjusted quantity-frequency method, with questions on occasions with heavy drinking, was used to estimate the consumption of alcohol during the last 30 days. The purpose was to analyze if it was possible to decrease the underestimation of true alcohol consumption. The questionnaire was mailed to a randomized sample of 1,500 individuals, 20-75 years of age, living in the city of Malmö, Sweden; 930 persons (64.3%) participated. Data on alcohol consumption were validated by comparison to sales of alcohol for the city of Malmö. The estimated per capita consumption of alcohol in the population was equivalent to 77.0% of the registered sale of alcohol in Malmö. By adding days with heavy drinking, the estimated weekly per capita consumption of alcohol among the alcohol consumers increased from 74.5 grams to 77.1 grams (+3.5%; p < .001). Of the alcohol consumers, 15.1% increased their reported consumption. In order to decrease even more the underestimation of the true alcohol consumption, we suggest the use of questions about any alcohol consumption that deviates from the typical consumption of each individual.

Adult↗
PubMed1992

Antirepression function in Escherichia coli for the cAMP-cAMP receptor protein transcriptional activator.

The cAMP receptor protein (CRP) complex (cAMP-CRP) is a global regulator of gene expression. It influences transcription from a number of promoters in Escherichia coli, including two divergently oriented promoters in the pap pili-adhesin gene system. To further define the role of cAMP-CRP in pap regulation we monitored protein-DNA interactions in vitro and levels of pap transcription in vivo in wild-type and mutant pap-containing clones. The results showed that activation was mediated by a single cAMP-CRP-binding site centered at nucleotide positions -215.5 and -115.5 relative to the transcriptional start points. A target for the pap-specific regulatory protein PapB was localized adjacent to the cAMP-CRP-binding site. The long-range effects exerted from the protein-binding sites were consistent with the idea that cAMP-CRP caused a change in the local DNA conformation and that a nucleoprotein complex (involving cAMP-CRP and PapB) was formed in the region between the pap promoters. Moreover, transcription became independent of activation of cAMP-CRP and the PapB protein in a mutant lacking the nucleoid-associated protein H-NS. Our findings suggest that the cAMP-CRP complex mediates its positive regulatory function by alleviating transcriptional silencing and, as such, plays a role as antirepressor.

Adhesins, Escherichia coli↗
PubMed1990

Transcriptional silencing and thermoregulation of gene expression in Escherichia coli.

Expression of specific adhesive properties by bacteria in general seems to be regulated to fit the environmental conditions. An example is the transcriptional regulation of digalactoside-specific binding by uropathogenic strains of Escherichia coli. The fimbrial structures (pili) on the bacterial surface carry the adhesin and are present during growth at 37 degrees C but are not produced by cells at lower temperatures, such as 25 degrees C. Thermoregulation of expression is due to temperature-dependent transcription of a regulatory cistron in the pilus-adhesin gene cluster. We have now identified and characterized a new regulatory locus (drdX) and show that a histone-like bacterial protein has an important role in this novel example of thermoregulation of transcription.

Adhesins, Bacterial↗
PubMed1989

Autoregulation and multiple DNA interactions by a transcriptional regulatory protein in E. coli pili biogenesis.

An operon mediating biogenesis of digalactoside-binding pilus-adhesin of serotype F13 in uropathogenic Escherichia coli includes the regulatory gene papB. The papB gene product was found to act as transcriptional activator of an operon which includes the papB gene and several pap cistrons encoding the proteins of the pilus polymer. Studies of how pap gene expression was affected by increasing amounts of PapB protein in the cells showed that high levels did not stimulate transcription but caused repression. Results from in vitro studies demonstrated that the PapB protein was a sequence-specific DNA-binding protein. Binding studies using gel mobility shift assays and DNase I protection (footprinting) showed that PapB protein binds to three separate sites. A sequence greater than 200 bp upstream of the promoter, and directly adjacent to a binding site for the cAMP receptor protein-cAMP complex, appeared as a preferential PapB binding site. A second site was localized to sequences overlapping the -10 region of the promoter and a third binding site was found within the coding sequence of the papB gene itself. The data suggest that the PapB protein has a dual function as activator/repressor of pilus-adhesin transcription and that its autoregulatory mode of action involves differential binding to separate sites.

Adhesins, Escherichia coli↗
PubMed1989

Regulatory genes in the thermoregulation of Escherichia coli pili gene transcription.

Expression of several different pilus adhesins by Escherichia coli is subject to thermoregulation. The surface-located fimbrial structures are present during growth at 37 degrees C but are not produced by cells grown at lower temperatures, such as 25 degrees C. As a step toward understanding the molecular mechanism, we have studied the role of different cistrons of a cloned pilus adhesin gene cluster (pap) from a uropathogenic E. coli isolate. By promoter cloning, mRNA analysis, and expression of subcloned genes in trans, we have identified the papI gene as the mediator of thermoregulation at the level of pilus adhesin gene transcription. Expression of the major pilus subunit gene (papA) and several other pilus protein cistrons appeared to be dependent on stimulation by the papB and papI gene products. Constructs carrying different pap DNA regions indicated that none of the known Pap proteins acts directly as thermosensor. The chromosomal rpoH gene and RpoH sigma factor did not appear to be required for pap transcription, and the thermoregulation of pilus gene transcription must be different from that of the heat shock regulon. By overexpressing the papI gene product from an expression plasmid in trans, we could circumvent the temperature regulation and turn on production of pilus adhesin at low temperature. Our results suggest that the level of mRNA encoding the PapI activator is limiting at low growth temperatures and that thermoregulation is due to a determinant in the papI-papB intercistronic region.

Adhesins, Escherichia coli↗
PubMed1989

Upstream activating sequences that are shared by two divergently transcribed operons mediate cAMP-CRP regulation of pilus-adhesin in Escherichia coli.

Transcription of the genes encoding pilus-adhesin of serotype F13 in digalactoside-binding Escherichia coli required activation by the cAMP-CRP complex. Analysis of protein-DNA interaction in vitro showed that CRP bound in a cAMP-dependent manner to a sequence located 0.2 kb upstream of the point of transcription initiation of the pilus subunit operon. The cAMP-CRP activation included, in addition to the main pilus operon, the oppositely oriented operon encoding the Papl regulatory protein. Furthermore, the auto-regulatory product of the promoter-proximal gene (papB) in the pilus subunit operon was found to stimulate the papl transcriptional unit. Thus the cAMP-CRP complex and PapB might act in concert and indirectly promote pili synthesis by stimulating expression of the Papl positive regulator. The results of trans-complementation experiments and analyses using lacZ operon fusion derivatives showed that the cAMP-CRP activation also operated directly in cis on the pilus subunit operon. The region containing the CRP binding site appeared to function as an upstream activating sequence since deletion abolished expression even when the pap regulatory proteins Papl and PapB were supplied in trans. The implications for possible mechanisms of transcriptional activation by the cAMP-CRP complex at this novel location between the two oppositely oriented operons are discussed.

Adhesins, Escherichia coli↗
PubMed1988

Processed mRNA with differential stability in the regulation of E. coli pilin gene expression.

E. coli expressing the papA-I genes produce pili that mediate specific adhesion to mammalian cells. We show that the major pilus subunit gene, papA, is part of a polycistronic transcriptional unit subject to specific posttranscriptional processing. A primary transcript also encoding the papB regulatory gene product is endonucleolytically cleaved, resulting in the rapid decay of the papB-encoding 5' half of the mRNA, whereas the papA-encoding 3' half remains as a quite stable transcript. Processing and differential mRNA stability thereby result in accumulation of mRNAs encoding only the major pilus subunit. A sequence immediately downstream of the papA coding region may serve as a stability determinant for the papA transcript and concomitantly attenuate read-through transcription into the minor pilus subunit gene papH. This suggests that differential expression of genes within an operon may include endo- and exonucleolytic processing of the mRNA.

Bacterial Outer Membrane Proteins↗
PubMed1988

Functional and structural homology among regulatory cistrons of pili-adhesin determinants in Escherichia coli.

Expression of the digalactoside-binding Pap pili involves two trans-acting regulatory genes, papB and papI. Using pap-lac operon fusions and DNA hybridization probes derived from pap DNA we tested whether or not other pili-adhesin determinants from different Escherichia coli strains encode homologs to the pap regulatory genes. Digalactoside-specific clones of serotypes F72 and F11 complemented papB and papI mutants of the Pap (serotype F13) clone and DNA hybridization analysis showed that the clones are homologous in the DNA sequences encoding the two regulatory genes. Similar results were obtained with an S-pili determinant which mediates binding to sialic acid-containing receptors and the findings suggest that the regulatory regions may be more conserved than other genes in different pili-adhesin gene clusters. Determinants for type 1-pili (mannose-specific binding) and for pili associated with enterotoxigenic E. coli (K88, K99, CFAI, CFAII) did not appear to contain DNA sequences homologous to papB or papI. E. coli strain J96, which was the origin of the pap DNA, was found to carry two additional copies of papB-papI homologous sequences in the chromosome. In strains expressing more than one kind of pili the trans-active gene products thereby may allow for regulatory interaction between separate pili-adhesin gene systems.

Base Sequence↗
PubMed1986

Overproduction and purification of the B2 subunit of ribonucleotide reductase from Escherichia coli.

The nrdB gene of Escherichia coli, coding for the B2 protein of ribonucleotide reductase, has been cloned in a runaway-replication vector. The runaway derivative pBEU17 carries the promoter-proximal portion of the E. coli alanyl-tRNA synthetase gene and proved useful for expressing cloned genes lacking their native transcription initiation signals. The alaS promoter is located approximately 500 base pairs upstream of a single BamHI restriction endonuclease cleavage site utilized in the construction of an expression recombinant plasmid, pBS1, for the nrdB product. After 5-h thermal induction of cells carrying the runaway recombinant pBS1, protein B2 constituted 40% of the soluble protein fraction of the cells. The high concentration of protein B2 in crude extracts of induced cells has enabled a simplified purification scheme to be developed for production of homogeneous and concentrated B2 preparations. Protein B2 produced from pBS1 is identical to the chromosomally encoded nrdB product of E. coli as regards molecular mass on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, enzyme activity, tyrosine radical content, and structure of the binuclear iron center. Amino acid sequence analysis showed that the two polypeptide chains of protein B2 are identical. They start with an alanine residue, and the first 30 residues confirmed the amino acid sequence predicted from the nucleotide sequence of the nrdB gene, apart from an NH2-terminal processing removal of the initiator methionine.

Amino Acid Sequence↗
PubMed1986

Oxidation of tricyclic antidepressant drugs, debrisoquine and 7-ethoxyresorufin, by human liver preparations.

Data obtained from human studies in vivo show that the dispositions of the tricyclic antidepressant drugs desmethylimipramine (DMI) and nortriptyline are related to the debrisoquine hydroxylation phenotype. To obtain insight into the enzymic mechanisms behind this, the metabolism of debrisoquine and antidepressant drugs by human liver preparations have been studied. The 2-hydroxylation of DMI in vitro correlates with the 4-hydroxylation of debrisoquine among various livers (rs = 0.90). Debrisoquine inhibits DMI hydroxylation competitively, and DMI inhibits debrisoquine hydroxylation, suggesting that DMI hydroxylation is catalysed by the debrisoquine hydroxylase in human liver. By monitoring the hydroxylation of DMI in various fractions during separation and purification of cytochrome P-450 from human liver microsomes we have purified a cytochrome P-450 which efficiently hydroxylates this drug. The apparently electrophoretically homogeneous enzyme had a molecular weight of 51,500 and hydroxylated DMI and debrisoquine at rates of up to 0.95 and 0.45 nmol/min . nmol P-450, respectively. This is probably the major debrisoquine hydroxylating cytochrome P-450 in man. Nortriptyline 10-hydroxylation correlates strongly (r = 0.96) with debrisoquine hydroxylation in human liver microsomes. Nortriptyline inhibits DMI-hydroxylation competitively, and the drug also inhibits the 4-hydroxylation of debrisoquine. Thus it is probable that nortriptyline is hydroxylated by debrisoquine hydroxylase. Imipramine N-demethylation did not correlate significantly (P greater than 0.1) with debrisoquine hydroxylation among microsomes from nine livers. However, if a liver from a subject, which was a poor metabolizer of debrisoquine in vivo, was included, a correlation was obtained (r = 0.79, P less than 0.01, N = 10). Imipramine demethylation also correlated with DMI-hydroxylation only if the 'poor metabolizer' liver was included (r = 0.75, P less than 0.05, N = 10). Debrisoquine inhibited imipramine demethylation competitively. The data indicate that imipramine can interact with debrisoquine- and DMI-hydroxylase, but it is uncertain if this enzyme plays an important quantitative role in its demethylation. Ethoxyresorufin O-deethylation correlated with DMI hydroxylation (r = 0.80) in human liver preparations, and DMI inhibited the former reaction in what is probably a mixed competitive-non-competitive inhibition. Liver preparations from a subject who was a poor oxidizer of debrisoquine both in vivo and in vitro had unusually low capacity to metabolize ethoxyresorufin. Thus ethoxyresorufin, at least partly, seems to interact with an enzyme that can metabolize DMI in human liver.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Transcriptional activation of a pap pilus virulence operon from uropathogenic Escherichia coli.

A gene cluster mediating production of pili in uropathogenic Escherichia coli was analysed with respect to regulation of pili synthesis. Two cistrons, papB and papI, were localized upstream of the major pilus subunit gene, papA. The papI-papB-papA region was characterized by nucleotide sequencing and by transcriptional analysis. The papA gene was primarily represented by an 800 nucleotide long transcript but was also co-transcribed with papB as a less abundant 1300 nucleotide long mRNA. Both transcripts presumably terminated at the same site downstream of the papA coding sequence. The weakly expressed papI gene was transcribed in the opposite direction to that of papB and papA. Studies with lacZ operon fusions showed that the papB gene encoded a trans-active effector required for papA transcription. Similarly, the papI gene stimulated papB transcription in trans. Furthermore, full expression of papA was cis dependent upon the papI-papB region. Transcription of the papB gene was shown to be dependent upon cAMP and its receptor protein. A binding site for the cAMP-CRP complex was postulated in the DNA sequence upstream of the papB promoter.

Amino Acid Sequence↗
PubMed1985

Inhibition of desmethylimipramine 2-hydroxylation by drugs in human liver microsomes.

The 2-hydroxylation of desmethylimipramine (DMI) correlates strongly with the 4-hydroxylation of debrisoquine (D) both in human volunteers and in vitro comparing human liver microsomes from different individuals. D competitively inhibits the 2-hydroxylation of DMI in vitro suggesting that DMI is hydroxylated by the 'debrisoquine hydroxylase' which is under monogenic control in man. We have characterized the effect of drugs on the hydroxylation of DMI in human liver microsomes by measuring the formation of 2-OH-DMI with HPLC using fluorescence detection. Amitriptyline, nortriptyline and metoprolol inhibited the hydroxylation of DMI competitively indicating interaction with the catalytical site for DMI 2-hydroxylation. Antipyrine and amylobarbitone at concentrations similar to their Km-values for metabolism did not inhibit DMI-hydroxylation. Thus, for these compounds there was a good correspondence between the drugs' capacity to inhibit DMI 2-hydroxylation competitively in vitro and their apparent metabolism by the 'debrisoquine hydroxylase' in vivo in man. Thioridazine, chlorpromazine, quinidine and quinine also inhibited DMI-hydroxylation competitively. Thioridazine was an unusually potent inhibitor (apparent inhibition constant Ki = 0.75 microM). Quinidine was also an unusually potent inhibitor (Ki = 0.27 microM) and much more efficient than its isomer quinine (Ki = 12 microM). Theophylline could inhibit DMI hydroxylation but with atypical kinetics. We suggest that this simple DMI in vitro test as well as earlier described inhibition tests with debrisoquine, sparteine and bufuralol can be used to screen if drugs interact with the 'debrisoquine hydroxylase' in human liver.

Amitriptyline↗
PubMed1985

Cryptic plasmid of Neisseria gonorrhoeae: complete nucleotide sequence and genetic organization.

The naturally occurring cryptic plasmid pJD1 of Neisseria gonorrhoeae is 4,207 base pairs long and is found in about 96% of gonococcal strains. The total probable coding capacity of pJD1 was determined from the complete nucleotide sequence by using computational probes to identify open reading frames with similar codon usage and by screening for the presence of ribosomal binding sites before the start codons. Candidates for promoters and terminators were also found in the sequence. Based on these findings, we propose a model for the genetic organization of the plasmid. The model predicts two transcriptional units, each composed of five compactly spaced genes. A promoter of one of the transcripts was shown to function in Escherichia coli, and the products of three of the five genes in this operon were identified in minicell expression experiments. Of these, the cppA gene encoded a 9-kilodalton protein, and the cppB and cppC genes both coded for 24-kilodalton proteins. No expression of the other transcriptional unit was detected, but two genes in this operon were expressed in minicells when transcribed from an E. coli promoter. The experimental data were consistent with the model.

Amino Acid Sequence↗
PubMed1984

Environmental temperature regulates transcription of a virulence pili operon in E. coli.

The expression in Escherichia coli K-12 of a pilus-adhesion determinant, obtained through molecular cloning from a pyelonephritic E. coli isolate, was studied at different temperatures. Strain HB101 carrying the recombinant plasmid pRHU845 agglutinated human erythrocytes after growth at 37 degrees C but not after growth at 22 degrees C. Quantitation of pilus subunit protein by an enzyme-linked immunosorbent assay (ELISA) for pilus antigen showed that synthesis of the pilus subunits was reduced at least 20-fold at 22 degrees C as compared with 37 degrees C. The 5' end of the pilus subunit structural gene, papA, was fused to the lacZ gene such that expression could be monitored at both translational and transcriptional levels. Measurements of beta-galactosidase production by the papA-lacZ hybrids provided evidence for thermoregulation of papA gene transcription. A regulatory determinant was localized to a 2-kb EcoRI-HindIII fragment encoding the papB gene and part of papA although none of the presently known pap gene products seem to be directly involved in a thermoregulatory mechanism. Comparison with other thermoregulatory systems in E. coli suggests that pap gene expression is regulated by a novel mechanism.

Base Sequence↗
PubMed1983

Correlation between nortriptyline and debrisoquine hydroxylation in the human liver.

The benzylic hydroxylation of nortriptyline (NT) and debrisoquine (D) by isolated human liver microsomes from eight subjects was studied. There was a strong correlation between the 10-hydroxylation of NT and the 4-hydroxylation of D (r = 0.96). The ability to hydroxylate D was also measured in vivo as the ratio between D and 4-OH-D in urine after oral administration of the drug to four subjects. This estimate of hydroxylation capacity agreed with the in vitro measurements. Liver microsomes from a subject defined as a poor in vivo oxidizer of D hydroxylated NT and D unusually slowly. Separation of microsomal proteins by SDS-gel electrophoresis indicated a relative lack of a cytochrome P-450 isozyme with a molecular weight of 54,500 in the liver from the poor oxidizer.

Adult↗
PubMed1983

Inulin single injection clearance. Microsample technique useful in children for determination of glomerular filtration rate.

The agreement between single injection inulin (polyfructosan) clearance and two reference methods for glomerular filtration rate (GFR) determination, namely standard inulin constant infusion clearance and 51-Cr-EDTA single injection clearance, was investigated. Studies were also made to see whether different results were obtained when capillary and venous blood samples were used in the single injection clearance method. The investigation was made in children from one year of age, adult patients and volunteers. For the single injection technique with inulin or 51-Cr-EDTA, five to seven blood samples were taken in a period of up to 180 min after injection. A bi-exponential plasma disappearance curve was used for calculations of single injection clearances. Good agreement was obtained between venous inulin single injection clearance on the one hand, and standard inulin clearance (correlation coefficient r = 0.86) and 51-Cr-EDTA single injection clearance on the other (r = 0.85). With use of capillary blood samples in inulin single injection clearance, similar good agreement was obtained both with venous 51-Cr-EDTA and with venous inulin single injection clearance (r = 0.85 and r = 0.89 respectively). From these results we conclude that inulin single injection clearance is a reliable method for GFR determinations. This method is recommended, especially in children, as capillary blood samples can be used.

Adolescent↗
PubMed1983

Evaluation of glomerular filtration rate in infants.

In the present study we investigated if inulin with single injection technique and capillary blood sampling can be used to determine glomerular filtration rate. Inulin single injection clearances using both venous and capillary samples were compared to standard inulin clearance (constant infusion) and to the clinical routine method, i.e. 51Cr-EDTA clearance. Good agreement was obtained between these different methods and it is concluded that the inulin single injection clearance is a reliable method for GFR estimation. Especially in children this method is recommended as capillary blood samples can be used and thus the high doses of radioactivity necessary for a 51Cr-EDTA capillary method can be avoided.

Adolescent↗