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C Dahl

Publications and source records attributed to C Dahl.

At least 19 recordsLinked to original sources
PubMed2006

Modulation of chemokine gene expression in CD133+ cord blood-derived human mast cells by cyclosporin A and dexamethasone.

We have recently developed a protocol for generating huge numbers of mature and functional mast cells from in vitro differentiated umbilical cord blood cells. Using CD133 as a positive selection marker to isolate haematopoietic progenitors we routinely expand the number of recovered cells at least 150-fold, which vastly exceeds the yields of conventional protocols using CD34+ cells as a source of progenitors. Taking advantage of the large quantities of in vitro differentiated mast cells, here we assess at the levels of transcription and translation the kinetics of chemokine gene induction following receptor mediated mast cell activation or following pharmacological activation of specific signal transduction cascades that become activated upon classical FcepsilonRI receptor crosslinking. We demonstrate that chemokine genes encoding IL-8, MCP-1, MIP-1alpha, and MIP-1beta are induced with different kinetics and with different amplitudes in a receptor activation dependent manner, and that these events can be mimicked using pharmacological agents which activate distinct signal transduction pathways. These findings were corroborated by adding immunomodulators such as cyclosporin A and dexamethasone prior to mast cell activation. Finally, we demonstrate that the same modulators added after mast cell activation can differentially quench ongoing chemokine gene induction. Thus, considering the vast yields of mast cells, our protocol is valuable not only for studying regulation of gene expression in mast cells in general, but also as an experimental tool to develop better and more balanced treatments of mast cell related disorders.

AC133 Antigen↗
PubMed2006

Identification of tryptase- and chymase-related gene clusters in human mast cells using microarrays.

Tryptase and chymase are the two major granular proteases present in human mast cell (MC)s. We used oligonucleotide microarray to measure the levels of approximately 22,000 transcripts in cord blood-derived MCs at 4 weeks, 8 weeks, 12 weeks and 18 weeks in culture. Tryptase (TPSB2) was expressed at the highest level among all transcripts and its expression level reached a plateau at 8 weeks. On the other hand, the expression level of chymase (CMAI) doubled every 4-6 weeks. A similar tendency was found at the protein levels with FACS analysis. After filtering the transcripts with MC-specificity, hierarchical clustering analysis identified 494 and 81 transcripts in the same clusters with tryptase and chymase, respectively. MC-specific genes, KIT and HDC were found in the tryptase cluster. In the chymase cluster, a critical suppressor for cell senescence, BMI1 and the several related genes were found, suggesting that chymase expression may be closely related to cell senescence/quiescence events.

Cells, Cultured↗
PubMed2006

Effect of a sustained silver-releasing dressing on ulcers with delayed healing: the CONTOP study.

OBJECTIVE: To compare the effect of the sustained silver-releasing foam dressing Contreet Foam (ColoplastA/S) with local best practice (LBP) on delayed healing ulcers using a real-life setting. METHOD: A total of 619 patients with ulcers of varying aetiologies were treated for four weeks with either the silver foam dressing or LBP. RESULTS: Wound area was reduced by 50% with the silver foam and 34% with LBP Less slough and maceration, a faster reduction in exudate level and more positive wound progress was achieved with the silver foam. In addition, exudate handling, ease of use, odour and pain improved. Less time was spent on dressing changes, and mean wear time was longer for the silver foam (3.1 days) than for LBP (2.1 days). All differences were statistically significant (p < 0.05). The silver foam dressing outperformed all of the other dressing categories including moist wound healing products and other silver dressings. CONCLUSION: This large-scale comparative real-life study shows that the silver foam dressing supports faster healing of delayed healing wounds.

Aged↗
PubMed2004

Human mast cells express receptors for IL-3, IL-5 and GM-CSF; a partial map of receptors on human mast cells cultured in vitro.

BACKGROUND: Mast cells have long been recognized as the principal cell type that initiates the inflammatory response characteristic of acute allergic type 1 reactions. Our goal has been to further characterize maturation of progenitors to mast cells. METHODS: Mast cells were cultured from human cord blood derived CD133(+) progenitors. Mast cell function was tested using histamine release. During differentiation mast cells surface marker expression was monitored by flow cytometry. RESULTS: CD133(+) progenitors expressed the early haematopoietic and myeloid lineage markers CD34, CD117, CD13 and CD33. Mature mast cells expressed CD117, CD13 and CD33, and expression of the high affinity immunoglobulin E receptor FcepsilonRI increased during culture. Cytokine receptors interleukin (IL)-5R, IL-3R, granulocyte-macrophage-colony stimulating factor (GM-CSF)R and IL-18R were expressed at high levels during maturation. Chemokine receptors CXCR4 and CXCR2 were highly expressed on both newly purified CD133(+) cells and mature cells. CONCLUSION: Human mast cells can be cultured from a CD34(+)/CD117(+)/CD13(+)/CD33(+) progenitor cell population in cord blood that is tryptase and chymase negative. Developing and mature mast cells express a wide range of chemokine and cytokine receptors. We found high levels of expression of CD123, IL-5R and GM-CSF receptors, also found on eosinophils and basophils, and high levels of expression of the receptor for the inflammatory cytokine IL-18.

AC133 Antigen↗
PubMed2004

Attention deficit hyperactivity disorder and suicide: a review of possible associations.

OBJECTIVE: To review the evidence of a possible association between attention deficit hyperactivity disorder (ADHD) and suicide. DESIGN: We searched the electronic data bases: Medline, Psych LIT, between 1966 and March 2003 looking for articles on ADHD, attention deficit disorder, hyperactivity and suicide. RESULTS: An association of ADHD and completed suicide was found, especially for younger males. However, the evidence for any direct or independent link was modest with an overall suicide rate from long-term follow-up studies of ADHD of 0.63-0.78%. The estimated relative risk ratio, compared with US national suicide rates (males 5-24 years) is 2.91 (95% confidence interval 1.47-5.7, chi2 = 9.3, d.f. = 1, P = 0.002). ADHD appears to increase the risk of suicide in males via increasing severity of comorbid conditions, particularly conduct disorder (CD) and depression. CONCLUSION: Identification of those at risk, particularly males with comorbid ADHD, depression and CD, may represent a useful clinical means of reducing completed suicide.

Adolescent↗
PubMed2003

Measurement of spin-correlation parameters ANN, ASS, and ASL at 2.1 GeV in proton-proton elastic scattering.

At the Cooler Synchrotron COSY/Jülich spin-correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for A(NN), A(SS), and A(SL) for c.m. scattering angles between 30 degrees and 90 degrees. Our data on A(SS)--the first measurement of this observable above 800 MeV--clearly disagrees with predictions of available pp scattering phase-shift solutions while A(NN) and A(SL) are reproduced reasonably well. We show that in the direct reconstruction of the scattering amplitudes from the body of available pp elastic scattering data at 2.1 GeV the number of possible solutions is considerably reduced.

Journal Article↗
PubMed2003

Lectins interact differentially with purified human eosinophils, cultured cord blood-derived mast cells and the myeloid leukaemic cell line AML14.3D10: induction of interleukin-4 secretion is conserved among granulocytes, but is not proportional to agglutination or lectin-glycoprotein interaction.

BACKGROUND: Atopy is closely associated with the cellular T helper type-2 (Th2) phenotype, that is dominated by the pleiotrophic cytokine IL-4. The cellular source of IL-4 has yet to be determined, although basophils have been proposed. Eosinophils and mast cells are likely contenders investigated here, and the eosinophil-like leukaemia line AML14.3D10 is compared to eosinophils as an in vitro culturable model for eosinophils. Lectins can cross-link-specific surface glycoproteins and are found in the ingested (processed foods) and inhaled (airborne pollen grains) human environment. Therefore it is of interest to determine whether lectins can elicit the release of IL-4 from Th2-associated granulocytes other than basophils. METHOD: This study investigated the ability of eosinophils, AML14.3D10 and mast cells to secrete preformed IL-4 in response to stimulation with lectins, and explored molecular mechanisms underlying the interaction. RESULTS: Purified eosinophils and basophils, and cultured mast cells and AML14.3D10 cells were incubated with 1 micro m lectin. Agglutination was scored by microscopy. IL-4 secretion was measured by enzyme-linked immunosorbent assay. Biotinylated lectins were used to determine binding to cells by flow cytometry and in lectin blots of sodium dodecyl sulphate (SDS) gels. DISCUSSION: Purified human eosinophils, AML14.3D10 cells and cultured mast cells secrete IL-4 with a pattern similar to that found in basophils when stimulated with a panel of reactive and unreactive lectins. The lectin SNA induces IL-4 secretion from mast cells and basophils, but not from eosinophils or AML14.3D10. Eosinophils appear to secrete only pre-formed IL-4, whereas mast cells may synthesize IL-4 on ligation with the lectin LCA. Lectins that agglutinate the granulocytes investigated do not necessarily induce secretion of IL-4. Lectins that elicit secretion of IL-4 bind more to eosinophils than unreactive lectins as determined by flow cytometry and lectin blotting of SDS gels. CONCLUSION: As granulocytes with functions related to that of basophils, eosinophils, AML14.3D10 and cultured mast cells respond to stimulation with lectins similarly to basophils. This emphasizes the possibility that eosinophils and mast cells may be linked in their cellular heritage as the cellular partners, and lectins as ligands, may contribute to the maintenance of a Th2-favoured microenvironment that is thought to underlie the allergic march.

Agglutination↗
PubMed2002

The effect of concurrent infections with Pasteurella multocida and Ascaridia galli on free range chickens.

Pasteurella multocida and Ascaridia galli are observed with high prevalences in free range chickens in Denmark, but the impact is unknown. A study was carried out to examine the interaction between A. galli and P. multocida in chickens and the impact on production. Five groups, each with 20 18-week-old Lohmann Brown chickens were infected. Group 1 was orally infected with 1000+/-50 embryonated A. galli eggs. Group 2 received 10(4) cfu P. multocida intratracheally. Group 3 was infected with A. galli and subsequently with P. multocida. Group 4 was infected with P. multocida followed by A. galli. Group 5 was the control. The study ran for 11 weeks where clinical manifestations, weight gain and egg production were recorded. Excretion of P. multocida was determined on individual basis and blood smears were made for differential counts. At the end of the study pathological lesions and the number of adult worms, larvae and eggs in the faeces were recorded. The birds were more severely affected when infected with both pathogens compared to single infections with A. galli or P. multocida, respectively. A lower weight gain and egg production was observed with dual infections. A. galli infection followed by a secondary P. multocida infection resulted in more birds with pathological lesions and continued P. multocida excretion. In conclusion a negative interaction between A. galli and P. multocida was observed and it is postulated that free range chickens are at higher risk of being subjected to outbreaks of fowl cholera when they are infected with A. galli.

Animals↗
PubMed2002

Leydig cell tumour--a rare testicular tumour.

Although Leydig cell tumour is a rare tumour which constitutes only 1-3% of all testicular tumours, still it is in the focus of interest because of the difficulties in determining its exact nature and subsequently the type of treatment and follow-up. We report a case of Leydig cell tumour with a review of the related literature.

Biopsy, Needle↗
PubMed2001

Enzymology and molecular biology of prokaryotic sulfite oxidation.

Despite its toxicity, sulfite plays a key role in oxidative sulfur metabolism and there are even some microorganisms which can use it as sole electron source. Sulfite is the main intermediate in the oxidation of sulfur compounds to sulfate, the major product of most dissimilatory sulfur-oxidizing prokaryotes. Two pathways of sulfite oxidation are known: (1) direct oxidation to sulfate catalyzed by a sulfite:acceptor oxidoreductase, which is thought to be a molybdenum-containing enzyme; (2) indirect oxidation under the involvement of the enzymes adenylylsulfate (APS) reductase and ATP sulfurylase and/or adenylylsulfate:phosphate adenylyltransferase with APS as an intermediate. The latter pathway allows substrate phosphorylation and occurs in the bacterial cytoplasm. Direct oxidation appears to have a wider distribution; however, a redundancy of pathways has been described for diverse photo- or chemotrophic, sulfite-oxidizing prokaryotes. In many pro- and also eukaryotes sulfite is formed as a degradative product from molecules containing sulfur as a heteroatom. In these organisms detoxification of sulfite is generally achieved by direct oxidation to sulfate.

Amino Acid Sequence↗
PubMed2001

Evidence for two pathways of thiosulfate oxidation in Starkeya novella (formerly Thiobacillus novellus).

The pathway of thiosulfate oxidation in the facultatively chemolithotrophic, sulfur-oxidizing bacterium Starkeya novella (formerly Thiobacillus novellus) has not been established beyond doubt. Recently, isolation of the sorAB genes, which encode a soluble sulfite:cytochrome c oxidoreductase, has been reported, indicating that a thiosulfate-oxidizing pathway not involving a multienzyme complex may exist in this organism. Here we report the cloning and sequencing of the soxBCD genes from S. novella, which are closely related to the corresponding genes encoding the thiosulfate-oxidizing multienzyme complex from Paracoccus pantotrophus. These findings suggest two distinct pathways for thiosulfate oxidation in S. novella. The expression of sorAB and soxC in cells grown on thiosulfate- and/or glucose-containing media was studied by Western blot analysis. The results showed that the SorAB protein is synthesized in the presence of thiosulfate irrespective of the presence of glucose. In contrast, the SoxC protein is subject to repression by glucose; the repression, however, appears to be dependent on the relative amounts of glucose and thiosulfate present. The regulatory effects observed for the expression of sorAB are likely to be mediated by an extracytoplasmic function sigma factor encoded by the sigE gene identified upstream of sorAB.

Amino Acid Sequence↗
PubMed2001

In vivo role of adenosine-5'-phosphosulfate reductase in the purple sulfur bacterium Allochromatium vinosum.

Adenosine-5'-phosphosulfate (APS) reductase participates in the oxidation of sulfite to APS in Allochromatium vinosum. Oxidation of sulfite via the APS pathway yields ATP through substrate-level phosphorylation. An alternative enzyme for the oxidation of sulfite to sulfate, sulfite:acceptor oxidoreductase, has also been reported in Ach. vinosum. Oxidation of sulfite through this enzyme does not yield ATP. APS reductase is expressed constitutively in Ach. vinosum, suggesting that it performs an important role in this organism. However, studies carried out with batch cultures of an APS reductase mutant showed little or no differences in growth or in the rates of substrate oxidation when compared to the wild-type, therefore questioning the role of this enzyme. In an attempt to establish whether the ATP gain derived from APS-reductase-mediated oxidation of sulfite is relevant for energy-limited cultures, we compared growth of the wild-type SM50 and the APS-reductase-deficient mutant D3 when grown in continuous culture under different degrees of illumination. Little differences in the specific growth rates of the two strains were observed at light-limiting irradiances, suggesting that the ATP gained during sulfite oxidation through the APS reductase pathway does not constitute a significant energy input. However, at saturating irradiances, wild-type Ach. vinosum grew considerably faster than the mutant. Increasing the irradiance even further resulted in inhibition of the wild-type strain down to the level of the APS reductase mutant. The implications of these results are discussed.

Chromatiaceae↗
PubMed2000

Sulfite:Cytochrome c oxidoreductase from Thiobacillus novellus. Purification, characterization, and molecular biology of a heterodimeric member of the sulfite oxidase family.

Direct oxidation of sulfite to sulfate occurs in various photo- and chemotrophic sulfur oxidizing microorganisms as the final step in the oxidation of reduced sulfur compounds and is catalyzed by sulfite:cytochrome c oxidoreductase (EC ). Here we show that the enzyme from Thiobacillus novellus is a periplasmically located alphabeta heterodimer, consisting of a 40.6-kDa subunit containing a molybdenum cofactor and an 8.8-kDa mono-heme cytochrome c(552) subunit (midpoint redox potential, E(m8.0) = +280 mV). The organic component of the molybdenum cofactor was identified as molybdopterin contained in a 1:1 ratio to the Mo content of the enzyme. Electron paramagnetic resonance spectroscopy revealed the presence of a sulfite-inducible Mo(V) signal characteristic of sulfite:acceptor oxidoreductases. However, pH-dependent changes in the electron paramagnetic resonance signal were not detected. Kinetic studies showed that the enzyme exhibits a ping-pong mechanism involving two reactive sites. K(m) values for sulfite and cytochrome c(550) were determined to be 27 and 4 micrometer, respectively; the enzyme was found to be reversibly inhibited by sulfate and various buffer ions. The sorAB genes, which encode the enzyme, appear to form an operon, which is preceded by a putative extracytoplasmic function-type promoter and contains a hairpin loop termination structure downstream of sorB. While SorA exhibits significant similarities to known sequences of eukaryotic and bacterial sulfite:acceptor oxidoreductases, SorB does not appear to be closely related to any known c-type cytochromes.

Amino Acid Sequence↗
PubMed2000

"ADP sulfurylase" from Thiobacillus denitrificans is an adenylylsulfate:phosphate adenylyltransferase and belongs to a new family of nucleotidyltransferases.

During AMP-dependent sulfite oxidation by some sulfur bacteria, the liberation of sulfate from adenosine-5'-phosphosulfate (APS) is catalyzed by APS:phosphate adenylyltransferase (APAT). Here we report the first biochemical and genetic characterization of APAT. We isolated this enzyme from the chemolithoautotroph Thiobacillus denitrificans and cloned the corresponding gene. The enzyme is homodimeric with 41,387-Da subunits and exhibits a specific activity of 2100 micromol min(-1) mg(-1). The K(m) values are K(m(APS)) = 300 microM and K(m(P(i))) = 12 mM. Catalysis occurs by a ping-pong mechanism with a covalently bound AMP as reaction intermediate. The arsenolysis of APS, but not of ADP, CDP, GDP, UDP, or IDP, is also catalyzed, indicating a specific and unidirectional function. The former enzyme name ADP-sulfurylase implies that the reverse reaction is catalyzed; therefore, this name should not be used any longer. Histidine modification of APAT results in complete inactivation that can be suppressed by substrate addition. APAT is highly similar to galactose-1-phosphate uridylyltransferase and also related to Ap(4)A phosphorylase. Active site residues of galactose-1-phosphate uridylyltransferase are conserved in APAT and Ap(4)A phosphorylase, suggesting a histidine as the nucleotide-binding residue in all three enzymes, which together form a new family of nucleotidyltransferases.

Amino Acid Sequence↗
PubMed2000

Reduced [3H]IP3 binding but unchanged IP3 receptor levels in the rat hippocampus CA1 region following transient global ischemia and tolerance induction.

Changes in inositol (1,4,5)-trisphosphate (IP3) binding properties and the protein level of the IP3 receptor have been reported in different pathological conditions in the brain, e.g. cerebral ischemia, Alzheimer's disease, and Huntingtons disease. We used the 4-vessel occlusion model in rat brain to investigate the effect of transient ischemia insults on the IP3 receptor mRNA level, the IP3 receptor protein level and [3H]IP3 binding. Recirculation periods were limited (1-72 h) to avoid the development of delayed neuronal death. We found that the IP3 receptor mRNA levels were decreased after damage-inducing ischemia (9 min) in the hippocampus CA1 and CA3 regions. The mRNA levels were unaltered after tolerance-inducing ischemia (3 min). However, [3H]IP3 binding was significantly reduced after both damage- and tolerance-inducing ischemia in the hippocampus CA1 region. Furthermore, all investigated brain areas showed a decreased [3H]IP3 binding when tolerance-inducing ischemia was followed by a second ischemic insult (3 + 8.5 min ischemia). The IP3 receptor protein levels remained constant in all investigated brain areas. These results indicate that a reduced [3H]IP3 binding capability in the particularly vulnerable areas occurs as an early consequence of cerebral ischemia, before IP3 receptor protein levels are reduced in these areas. Structural or conformational changes altering IP3 binding may be of necessity on the pathway leading to down-regulation of IP3 receptor protein levels, as observed by others.

Adaptation, Physiological↗