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L Nilsson

Publications and source records attributed to L Nilsson.

At least 253 records · Page 14Linked to original sources
PubMed1991

Structure of TGF-beta 1-induced human immunoglobulin C alpha 1 and C alpha 2 germ-line transcripts.

We have characterized the structure of the human immunoglobulin C alpha 1 and C alpha 2 germ-line transcripts that are synthesized upon treatment of human B lymphocytes with Branhamella catarrhalis (a B cell mitogen) and transforming growth factor beta 1 (TGF-beta 1). These transcripts initiate upstream of the switch alpha 1 and switch alpha 2 regions and contain, together with the C alpha 1 and C alpha 2 sequences, additional exons designated according to the generally accepted nomenclature I alpha 1 and I alpha 2 respectively. The I alpha exons are spliced directly onto the acceptor splice site of the CH1 domains of the C alpha 1 and C alpha 2 genes. As in other previously characterized germ-line transcripts, stop codons present in all three reading frames prevent translation of the C alpha 1 and C alpha 2 heavy-chain coding sequences. The longest open reading frame (ORF) present in the I exons can code for a polypeptide of only 26 amino acids. The human I alpha exons do not show any significant sequence homology with the corresponding mouse I alpha exon. However, comparison of nucleotide sequences of the genomic mouse and human I alpha regions demonstrated the presence of an approximately 300 bp highly conserved element located immediately upstream of the transcription initiation sites of the human and mouse C alpha germ-line transcripts. The isolation of the C alpha 1 and C alpha 2 germ-line transcripts will further facilitate the characterization of the molecular events responsible for the regulation of the human C alpha heavy chain loci.

Base Sequence↗
PubMed1991

Radioimmunoassay of human eosinophil cationic protein (ECP) by an improved method. Establishment of normal levels in serum and turnover in vivo.

A radioimmunoassay was developed allowing measurement of the cytotoxic cationic ECP. The assay, which has a total incubation time of 3.5 hr, is a double antibody assay with radiolabelled ECP, covering the concentration range of 2-200 micrograms/l. Performance data show a detection limit of less than 2 micrograms/l and a cross-reactivity with eosinophil protein X (EPX/EDN) of less than 0.06%. The coefficient of variation (%) within the measuring range was, within assay 4.8-10.4, and total 6.6-12.0. The assay is useful for measurement in various body fluids including serum, nasal secretions and bronchoalveolar lavage fluid, and dilution of samples prior to analysis was generally not required. Sera from 100 apparently healthy individuals revealed a geometric mean of 6.0 micrograms ECP/l and a range (95%) of 2.3-15.9 micrograms/l. The elimination rate of ECP, t1/2, in vivo was estimated to be 65 min when ECP was measured in serum. Comparisons between this assay and a method previously described showed that the new method is superior with regard to precision and assay procedure.

Blood Proteins↗
PubMed1991

Quantitative and qualitative analysis of human IgG subclass specific mRNA using solution hybridization.

Four IgG subclasses have been identified in the human system. Despite the fact that they exhibit differences in their functional properties, antigenic properties and chemical composition and demonstrate age-related shifts in their expression, the genes coding for their constant regions show extensive homology at the nucleotide level (greater than 95%). The only parts of the C gamma genes that show significant variation among the different IgG subclasses are the exons coding for their hinge regions (less than 60%). Taking advantage of such sequence variation, we have developed specific RNA probes which allowed us to analyse the expression of the C gamma 1, C gamma 2, C gamma 3 and C gamma 4 genes at the mRNA level using solution hybridization. We have defined optimal conditions that allow the detection of picogram levels of IgG subclass specific mRNA, while keeping the cross-reactivity between the different probes below 2%. This approach will significantly facilitate studies aiming at characterizing the molecular mechanisms regulating the expression of the four human IgG heavy chain constant region genes.

Base Sequence↗
PubMed1991

Reduced granulocyte activation with a heparin-coated device in an in vitro model of cardiopulmonary bypass.

Granulocyte activation during cardiopulmonary bypass (CPB), resulting in degranulation, may have adverse effects. Fresh whole human blood and priming solution was circulated through oxygenator/tubing sets coated with functional heparin (n = 7) and through uncoated sets (n = 7) in model CPB. Plasma concentrations of the primary granule protein myeloperoxidase (MPO) and the secondary granule protein lactoferrin (LF) were measured in radioimmunoassays, and the neutrophils were counted. After 120 min, seven to nine times baseline concentrations of LF (p less than 0.0001) were observed with both devices. Increases of MPO were also significant, but significantly larger (p less than 0.01) with the uncoated devices. There was an equivalent reduction in neutrophil numbers in both groups. MPO did not bind to heparin-coated Sephadex particles in gel chromatography. Thus, the heparin coating most likely prevented the release of potentially harmful primary granule proteins, indicating improved biocompatibility. Adhesion of neutrophils and exocytosis of LF, which may be involved in adhesion, were unaffected.

Biocompatible Materials↗
PubMed1991

Formation of nonculturable Vibrio vulnificus cells and its relationship to the starvation state.

Entry into the viable but nonculturable state by the human bacterial pathogen Vibrio vulnificus in artificial seawater microcosms was studied. In contrast to the long-term culturability exhibited by cells incubated under these starvation conditions at room temperature, cells exposed to a temperature downshift to 5 degrees C exhibited an immediate decrease in culturability. Cells incubated at low temperature exhibited a morphological change from rods to cocci but demonstrated no reductive division. Of 10 factors studied which might affect the nonculturable response in V. vulnificus, only the physiological age of the cells was found to significantly affect the rate at which cells became nonculturable. The nonculturable response appears to be related to the starvation response, as prestarvation at room temperature for 24 h was found to eliminate the nonculturable response of cells subsequently incubated at 5 degrees C. This observation suggests that the synthesis of starvation proteins may repress the viable but nonculturable program displayed during low-temperature incubation. The possible ecological significance of these findings is discussed.

Colony Count, Microbial↗
PubMed1991

Resuscitation of Vibrio vulnificus from the viable but nonculturable state.

Stationary-phase-grown cells of the estuarine bacterium Vibrio vulnificus became nonculturable in nutrient-limited artificial seawater microcosms after 27 days at 5 degrees C. When the nonculturable cells were subjected to temperature upshift by being placed at room temperature, the original bacterial numbers were detectable by plate counts after 3 days, with a corresponding increase in the direct viable counts from 3% to over 80% of the total cell count. No increase in the total cell count was observed during resuscitation, indicating that the plate count increases were not due to growth of a few culturable cells. Chloramphenicol and ampicillin totally inhibited resuscitation of the nonculturable cells when added to samples that had been at room temperature for up to 24 h. After 72 h of resuscitation, the inhibitors had an easily detectable but reduced effect on the resuscitated cells, indicating that protein and peptidoglycan synthesis were still ongoing. Major changes in the morphology of the cells were discovered. Nonculturable cells of V. vulnificus were small cocci (approximately 1.0 micron in diameter). Upon resuscitation, the cells became large rods with a size of mid-log-phase cells (3.0 microns in length). Four days after the cells had become fully resuscitated, the cell size had decreased to approximately 1.5 micron in length and 0.7 micron in width. The cells were able to go through at least two cycles of nonculturability and subsequent resuscitation without changes in the total cell count. This is the first report of resuscitation, without the addition of nutrient, of nonculturable cells, and it is suggested that temperature may be the determining factor in the resuscitation from this survival, or adaptation, state of certain species in estuarine environments.

Ampicillin↗
PubMed1991

Late seroconversion to hepatitis B in a Somali village indicates the important role of venereal transmission.

Hepatitis B virus (HBV) markers were investigated in a cross-sectional study in 1985 on sera from 84% of the 648 inhabitants in a rural Somali village. The prevalence of HBV markers increased with age, from 9.7% in subjects less than 12 years old, to 38% in the age group 12-19 years, and to 68% in adults. HBV markers were more common in boys less than 12 years old, 13%, than in girls of the same age group, 5.8% (P less than 0.05). A rapid increase of HBV markers started at adolescence in both sexes. The female cohort showed their highest seroconversion rate during their second decade of life, while the male cohort seroconverted more rapidly in the third decade. Thus, an initially more rapid seroconversion among boys was reversed when the females reached reproductive age, and no sex difference in marker frequencies was observed in the age group 12-19 years. There was a steady increase of HBV markers during the reproductive years in both sexes. The frequencies of HBsAg, as well as total markers, were significantly higher in adult males than females, 14 vs 5.6%, and 77 vs 62%, respectively. HBV markers were more frequent in wives of HBV positive husbands than in those married to HBV negative husbands. No increased marker prevalence was observed among siblings of HBV positive children, nor among their mothers, which disproved the role of vertical and early horizontal transmission. In 1989 the four-year rate of seroconversion was investigated in villagers who were seronegative in 1985. On testing 158 sera from 319 individuals, the seroconversion rate was significantly lower among those younger than 12 years in 1985 compared to those in the older age group, 5 vs 17%.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

2,3-Butanediol in plasma from an alcoholic mistakenly identified as ethylene glycol by gas-chromatographic analysis.

2,3-Butanediol was mistakenly identified as ethylene glycol in plasma specimens from two alcoholic patients. The cyclic phenylboronate ester derivatives of 2,3-butanediol and ethylene glycol had the same retention time when OV-17 was used as the stationary phase for gas chromatography. This led to incorrect diagnosis of ethylene glycol poisoning and unnecessary invasive therapy. Plasma from two chronic alcoholics contained 2,3-butanediol at 3.5 and 3.4 mmol/L. The elimination half-life of 2,3-butanediol was 3.9 days when ethanol was administered during therapy for suspected ethylene glycol poisoning. Low concentrations of 2,3-butanediol might be present in blood of chronic alcoholics as a result of a novel pathway of intermediary metabolism associated with some forms of alcoholism. However, a more likely explanation for fairly high concentrations of 2,3-butanediol is enzymatic production from 2-butanone. This ketone occurs in denatured alcohol preparations often consumed by alcoholics in Sweden.

Adult↗
PubMed1990

Three-dimensional model and molecular dynamics simulation of the active site of the self-splicing intervening sequence of the bacteriophage T4 nrdB messenger RNA.

The secondary and 3D structure of the active site of the self-splicing T4 nrdB RNA has been modeled on a graphics workstation by use of the suggested 3D arrangement of the active site of the Tetrahymena IVS [Kim, S.H., & Cech, T.R. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 8788-8792] as a guideline. The initially obtained crude structure was then subjected to molecular mechanics energy minimization and molecular dynamics simulation to relax tensions. In this process the energy decreased considerably and gave a final structure that deviated by 3 A [root mean square (rms)] from the initial structure. The cofactor guanosine (and the competitive inhibitor arginine) was docked to a proposed [Michel, F., Hanna, M., Green, R., Bartel, D.P., & Szostak, J.W. (1989) Nature 342, 391-395] binding site, where it was found to fit rather well. A minor modification of the binding mode easily brought the O3' end of the guanosine within 2 A of the phosphodiester bond where the primary cleavage occurs.

Animals↗
PubMed1990

Studies on lipoamidase: characterization of the enzyme in human serum and breast milk.

Lipoamidase activity was detected in human serum with both lipoyllysine (epsilon-N-(DL-lipoyl)-L-Lysine) and lipoylPABA (N-DL-lipoyl-p-aminobenzoate) as substrates, whereas lipoamidase in human milk used lipoylPABA, but not lipoyllysine as substrate. This suggested that lipoamidase activities in serum and milk are due to different enzymes. Studies with activators and inhibitors suggested that lipoamidase in serum using lipoylPABA as substrate may be a different enzyme from that using lipoyllysine as substrate. We suggest that these lipoamidases are named lipoyllysine hydrolase (LLH) and lipoylPABA hydrolase (LPH), respectively. Serum LLH was activated by thiol compounds and EDTA and strongly inhibited by sulfhydryl reagents whereas serum LPH was inhibited by sulfhydryl reagents but not activated by thiol compounds or EDTA. Milk LPH was unaffected by these reagents. We suggest that serum LLH and possibly serum LPH are cysteine proteases. LLH was adsorbed on Concanavalin A-Sepharose, indicating that LLH was a glycoprotein.

4-Aminobenzoic Acid↗
PubMed1990

FIS-dependent trans-activation of tRNA and rRNA operons of Escherichia coli.

Two mechanisms controlling stable RNA synthesis have been described: growth rate-dependent control and stringent response. Although the mechanism underlying growth rate-dependent control is still a matter of dispute, this control is commonly assumed to operate through repression of transcription initiation of stable RNA operons. The same is true for the stringent response. Here we show that the cell utilizes an additional control system operating through activation of the thrU(tufB) operon. This operon, the tyrT and the rrnB operon share a common trans-activating protein that binds to cis-acting DNA regions upstream of the promoters of the two tRNA operons and of the P1 promoter of the rrnB operon. Conceivably, more stable RNA operons may be regulated by trans-activation. Both in vivo and in vitro experiments show that the Escherichia coli protein FIS (Factor for Inversion Stimulation) is involved in the trans-activation. This protein is known to stimulate the inversion of various DNA segments by binding to cis-acting recombinational enhancers and functions as a host factor for the bacteriophages Mu and Lambda.

Bacteriophage mu↗
PubMed1990

Potential binding sites of the trans-activator FIS are present upstream of all rRNA operons and of many but not all tRNA operons.

FIS, the Escherichia coli protein that stimulates the inversion of various DNA segments by binding to a recombinational enhancer, trans-activates a number of stable RNA operons and binds to the upstream activator sequence (UAS) of these operons (Nilsson et al. (1990) EMBO J. 9, 727). In a search for potential FIS-binding sites we have compared UASs of other stable RNA operons with a consensus FIS-binding sequence, compiled by comparing recombinational enhancers. Such sites can thus be recognized upstream of all rRNA and 13 tRNA operons. Matching with the consensus sequence varied, suggesting that the affinity of FIS for the sites differed. Accordingly, FIS binding to an upstream sequence of the metY(nusA) operon was found to be weaker than that to the UAS of the thrU(tufB) operon. No FIS binding sites were found upstream three tRNA operons.

Anticodon↗
PubMed1990

Kinetic determination of the effects of ADP-ribosylation on the interaction of eukaryotic elongation factor 2 with ribosomes.

The effect of ADP-ribosylation on the function of eukaryotic elongation factor 2 (EF-2) was investigated by kinetic analysis of the EF-2-catalyzed hydrolysis of GTP in the presence of ribosomes and by direct determination of the affinity of the modified factor for the ribosome. Under conditions where the concentration of EF-2 was rate-limiting, the ADP-ribosylation reduced the maximum rate of GTP hydrolysis and the second order rate constant Kcat/Km by approximately 50%. A similar decrease in Kcat and Kcat/Km was observed when the concentration of ribosomes were kept rate-limiting. The affinity of EF-2 for the pretranslocation type of ribosomes was reduced by 2 orders of magnitude after ADP-ribosylation. No effect was observed in the interaction with the post-translocation type of ribosomes, the ribosomal conformation responsible for activation of the EF-2-dependent GTPase. We conclude that the ADP-ribosylation affects both the association of the modified factor with pretranslocation ribosomes and the hydrolytic capacity of the factor.

Adenosine Diphosphate Ribose↗
PubMed1990

The role of FIS in trans activation of stable RNA operons of E. coli.

The thrU(tufB) operon of Escherichia coli is endowed with a cis-acting region upstream of the promoter, designated UAS for Upstream Activator Sequence. A protein fraction has been isolated that binds specifically to DNA fragments of the UAS, thus forming three protein-DNA complexes corresponding to three binding sites on the UAS. It stimulates in vitro transcription of the operon by facilitating the binding of the RNA polymerase to the promoter. All three protein-DNA complexes contain one and the same protein. Dissociation constants for the three complexes have been determined, the lowest being in the sub-nanomolar range. The protein also binds to the UAS of the tyrT operon and to the UAS upstream of the P1 promoter of the rrnB operon, suggesting that transcription of the three operons, if not of more stable RNA operons, is activated by a common trans activator. We demonstrate that the E.coli protein FIS (Factor for Inversion Stimulation) also binds to the UAS of the thrU(tufB) operon forming three protein-DNA complexes. A burst of UAS- and FIS-dependent promoter activity is observed after reinitiation of growth of stationary cultures in fresh medium.

Carrier Proteins↗
PubMed1990

Effect of dietary supplement on nutritional status and clinical outcome in 501 geriatric patients--a randomised study.

The present study was designed to evaluate to the effect of dietary supplements on clinical outcome and nutritional status in a large group of geriatric patients (n = 501). The patients were randomised into an experimental group which received nutritional supplementation (400 kcal) as well as a standard hospital diet, and a control group on hospital diet alone. The nutritional state was measured on admission and after 8 and 26 weeks by anthropometry, serum protein analysis and a delayed hypersensitivity skin test. Protein energy malnutrition was defined as the presence of three or more abnormal parameters. 28.5% of patients showed evidence of malnutrition on admission. Hospitalisation itself resulted in a gradual deterioration in nutritional status. Nutritional supplementation generally improved nutritional state. Among those patients who were well nourished on admission, and subsequently receiving dietary supplementation, 8.3% fulfilled malnutrition criteria after 26 weeks, while 21.1% were considered malnourished in the control group (p < 0.05). The improvement observed in transport proteins was probably related to nutritional support and not just to the reversal of inflammation. In the initially well nourished group of more than 300 patients, the mortality rate was 8.6% in those given nutritional support compared to 18.6% in the control group (p < 0.02).

Journal Article↗
PubMed1990

Human gonadotrophins.

Treatment with exogenous gonadotrophic hormones to overcome certain cases of female infertility has been used for more than 30 years. Children born after such treatment have not shown any increased incidence of abnormalities (genetic or otherwise) and their reproductive ability seems normal. Furthermore, no increase in malignant disease (breast, ovarian, endometrial) have been reported following such repetitive gonadotrophic stimulations. Thus it seems the treatment can be regarded as safe. Two categories of patients are treated today. Firstly, hypothalamic-hypophyseal insufficiencies (WHO group I), where treatment is compulsory for attaining fertility, and secondly (including anovulation WHO group II), more or less regularly cycling women, where gonadotrophic treatment is used to augment fertility. Especially in the latter group, caution must be taken not to induce adverse effects. To meet these demands, exogenous gonadotrophic stimulation needs to be combined with other drugs and regimens that take into consideration the problems created by the concomitant presence of endogenous gonadotrophins.

Anovulation↗