Search PubMed⌕ Search

Biomedical subjects

M Larsson

Publications and source records attributed to M Larsson.

At least 55 records · Page 3Linked to original sources
PubMed2001

Mature dendritic cells infected with canarypox virus elicit strong anti-human immunodeficiency virus CD8+ and CD4+ T-cell responses from chronically infected individuals.

Recombinant canarypox virus vectors containing human immunodeficiency virus type 1 (HIV-1) sequences are promising vaccine candidates, as they replicate poorly in human cells. However, when delivered intramuscularly the vaccines have induced inconsistent and in some cases transient antigen-specific cytotoxic T-cell (CTL) responses in seronegative volunteers. An attractive way to enhance these responses would be to target canarypox virus to professional antigen-presenting cells such as dendritic cells (DCs). We studied (i) the interaction between canarypox virus and DCs and (ii) the T-cell responses induced by DCs infected with canarypox virus vectors containing HIV-1 genes. Mature and not immature DCs resisted the cytopathic effects of canarypox virus and elicited strong effector CD8+ T-cell responses from chronically infected HIV+ individuals, e.g., cytolysis, and secretion of gamma interferon (IFN-gamma) and beta-chemokines. Furthermore, canarypox virus-infected DCs were >30-fold more efficient than monocytes and induced responses that were comparable to those induced by vaccinia virus vectors or peptides. Addition of exogenous cytokines was not necessary to elicit CD8+ effector cells, although the presence of CD4+ T cells was required for their expansion and maintenance. Most strikingly, canarypox virus-infected DCs were directly able to stimulate HIV-specific, IFN-gamma-secreting CD4 helper responses from bulk as well as purified CD4+ T cells. Therefore, these results suggest that targeting canarypox virus vectors to mature DCs could potentially elicit both anti-HIV CD8+ and CD4+ helper responses in vivo.

AIDS Vaccines↗
PubMed2001

Novel candidate genes for atherosclerosis are identified by representational difference analysis-based transcript profiling of cholesterol-loaded macrophages.

OBJECTIVES: To analyze the early gene expression in macrophages accompanying the phenotypic changes into foam cells upon exposure to oxidized low-density lipoprotein. To identify candidate genes and markers for further studies into the pathogenesis of atherosclerosis. METHODS: Cells of the monocytic cell line THP-1 were activated by PMA and exposed to oxidized low-density lipoprotein. Gene expression profiles were investigated after 24 h, using a solid phase cDNA representational difference analysis (RDA) method and shotgun sequencing. Results were verified by microarray hybridization, and analyzed in the virtual chip display of a novel software tool for transcript profile exploration. RESULTS: By comparing transcript profiles of exposed/unexposed cells, 1,984 transcript sequences, representing a total of 921 genes with altered expression levels in response to oxidized low-density lipoprotein exposure, were identified. Genes that are central to cell cycle control and proliferation, inflammatory response, and of pathways not previously implicated in atherosclerosis were identified. The data obtained is also made available on-line at http:// biobase.biotech.kth.se/thp1a for further exploration. CONCLUSION: The identification of new candidate genes for atherosclerotic disease through RDA-based transcript profiling facilitates further functional genomic studies in coronary artery disease. Candidate genetic polymorphism markers of potential clinical relevance can be identified by filtering information in genome variation databases through the virtual chip analysis of the transcript profiles and subsequently tested in association studies.

Arteriosclerosis↗
PubMed2001

EBNA1-specific CD4+ T cells in healthy carriers of Epstein-Barr virus are primarily Th1 in function.

The Epstein-Barr virus (EBV) nuclear antigen-1 (EBNA1) maintains the viral episome in all host cells infected with EBV. Recently, EBNA1 was found to be the main EBV latency antigen for CD4+ T cells and could be recognized in cultures from all donors tested. We now identify a polarized Th1 phenotype and obtain evidence for its presence in vivo. When T cells were stimulated with dendritic cells infected with vaccinia vectors expressing EBNA1, 18 of 19 donors secreted IFN-gamma, whereas only two of 19 secreted IL-4. Magnetic selection was then used to isolate cells from fresh blood based on EBNA1-induced cytokine production. Specific IFN-gamma CD4+ cell lines were established from six of six donors and IL-4 lines from three of six. Only the Th1 lines specifically lysed targets expressing three different sources of EBNA1 protein. When the IgG isotype of EBNA1 plasma Ab's was tested, most specific Ab's were IgG1 and of a high titer, confirming a Th1 response to EBNA1 in vivo. Ab's to other microbial antigens generally were not skewed toward IgG1. Given emerging evidence that Th1 CD4+ T cells have several critical roles in host defense to viral infection and tumors, we propose that EBNA1-specific CD4+ Th1 cells contribute to resistance to EBV and EBV-associated malignancies.

Antibodies, Viral↗
PubMed2001

Management of childhood acute respiratory infections at private pharmacies in Vietnam.

OBJECTIVE: To investigate the knowledge and practice among private pharmacy staff in Hanoi regarding case management of mild acute respiratory infection (ARI) in children. METHODS: Sixty private pharmacies in Hanoi were randomly selected. Knowledge was assessed through interviews with pharmacy staff using a questionnaire; practice was assessed through the Simulated Client Method. RESULTS: In the questionnaire, 20% of the pharmacy staff stated that they would dispense antibiotics. In practice, 83% of the pharmacies dispensed antibiotics. Only 36% of the cases were handled according to guidelines. In the questionnaire, 81% of interviewees stated that antibiotics are not effective in short therapeutic courses. In practice, 48% of the antibiotics were dispensed in courses less than five days. Traditional herbal medicines were dispensed in 41% of the encounters. In the questionnaire, 53% of the pharmacy staff stated that they would ask the patient about difficulty of breathing. In practice, questions related to difficulty of breathing were asked in less than 10% of the encounters. CONCLUSIONS: Dispensing of antibiotics for mild ARI was common practice among private pharmacies, and there was a significant difference between knowledge and practice. Interventions are needed to improve pharmacy practice in Hanoi.

Acute Disease↗
PubMed2000

Dynamics of three-body breakup in dissociative recombination: H(2)O(+).

To better understand the propensity for the three-body breakup in dissociative recombination (DR) of dihydrides ( H(3)(+), NH(2)(+), CH(2)(+), and H(2)O(+)), we undertook a study of the dynamics of this process. A study of DR of H(2)O(+) to give O + H + H was carried out at the CRYRING Heavy-Ion Storage Ring in Stockholm. With the stored beam energy of 4.5 MeV, we separated the O signal from the H signals with a differential absorber, thus reducing the problem to a sum of two two-body problems. Results included (1) the ratio of O((3)P) to O((1)D) product, (2) the distribution of recoil-kinetic energy between the two hydrogen atoms, (3) the angular distribution between the hydrogen atoms in the O((3)P) channel and in the O((1)D) channel.

Journal Article↗
PubMed2000

Measurement of ligand distribution in individual adsorbent particles using confocal scanning laser microscopy and confocal micro-Raman spectroscopy.

Two methods, confocal scanning laser microscopy and confocal micro-Raman spectroscopy were used to analyse the distribution of IgG antibodies immobilized on CNBr-activated agarose beads. In the first method the internal distribution profile of fluorescent labelled Protein A was used as an indirect measure of the distribution of IgG, while the second method detects vibrations originating from aromatic amino acids present in the immobilized antibodies. Both these methods indicate an homogeneous ligand distribution within IgG Sepharose 4 Fast Flow and IgG Sepharose 6 Fast Flow.

Adsorption↗
PubMed2000

Requirement of mature dendritic cells for efficient activation of influenza A-specific memory CD8+ T cells.

It is critical to identify the developmental stage of dendritic cells (DCs) that is most efficient at inducing CD8+ T cell responses. Immature DCs can be generated from monocytes with GM-CSF and IL-4, while maturation is accomplished by the addition of stimuli such as monocyte-conditioned medium, CD40 ligand, and LPS. We evaluated the ability of human monocytes and immature and mature DCs to induce CD8+ effector responses to influenza virus Ags from resting memory cells. We studied replicating virus, nonreplicating virus, and the HLA-A*0201-restricted influenza matrix protein peptide. Sensitive and quantitative assays were used to measure influenza A-specific immune responses, including MHC class I tetramer binding assays, enzyme-linked immunospot assays for IFN-gamma production, and generation of cytotoxic T cells. Mature DCs were demonstrated to be superior to immature DC in eliciting IFN-gamma production from CD8+ effector cells. Furthermore, only mature DCs, not immature DCs, could expand and differentiate CTL precursors into cytotoxic effector cells over 7 days. An exception to this was immature DCs infected with live influenza virus, because of the virus's known maturation effect. Finally, mature DCs pulsed with matrix peptide induced CTLs from highly purified CD8+ T cells without requiring CD4+ T cell help. These differences between DC stages were independent of Ag concentrations or the number of immature DCs. In contrast to DCs, monocytes were markedly inferior or completely ineffective stimulators of T cell immunity. Our data with several qualitatively different assays of the memory CD8+ T cell response suggest that mature cells should be considered as immunotherapeutic adjuvants for Ag delivery.

CD8-Positive T-Lymphocytes↗
PubMed2000

High-throughput protein expression of cDNA products as a tool in functional genomics.

A proteomics approach has been developed aimed to allow high throughput analysis of protein products expressed from cDNA fragments (expressed sequence tags, ESTs). The concept relies on expression of gene products to generate specific antibodies for protein analysis, such as immunolocalization of the proteins on cellular and subcellular level. To evaluate the system, 55 cDNA clones with predominantly unknown function were selected from a mouse testis cDNA-library. A bacterial expression system was designed that allowed robust expression and easy purification. Protein levels between 15 and 80 mg l(-1) were obtained for 49 of the clones. Five clones were selected for immunization and all yielded functional antibodies that gave specific staining in Western blot screening of samples from various cell types. Furthermore, extensive immunolocalization information on subcellular level was obtained for three of the five clones. All generated data were stored in a relational database, and are made available through a web-interface (http://www.biochem.kth.se/multiscale/), which also provides relevant links and allows homology searches from the original sequences. The possibility to allow analysis of gene products from whole genomes using this 'localization proteomics' approach is discussed.

Amino Acid Sequence↗
PubMed2000

Strong human immunodeficiency virus (HIV)-specific CD4+ T cell responses in a cohort of chronically infected patients are associated with interruptions in anti-HIV chemotherapy.

Virus-specific CD4+ T-helper cell function is important in controlling human immunodeficiency virus (HIV) infection but is impaired in patients with progressive HIV disease. It has been reported that after highly active antiretroviral therapy (HAART), HIV-specific lymphoproliferative responses remain absent, whereas responses to non-HIV microbial antigens are restored. However, in analyzing immune responses in a cohort of chronically infected adults on HAART, we observed strong HIV-specific CD4+ T cell responses of Th-1 phenotype in 11 of 22 patients. The magnitude and frequency of HIV-specific lymphoproliferative responses was strongly associated with previous interruptions in HAART (P=.001). In contrast, the magnitude of CD8+ T cell responses to HIV Gag, Pol, Env, and Nef was similar in patients who had and those who had not interrupted HAART. We conclude that (1) a significant proportion of chronically HIV-infected patients on HAART can generate strong HIV-specific CD4+ and CD8+ T cell immunity and (2) transient interruptions in antiviral treatment may prime or boost HIV-specific CD4+ T-helper responses.

Adult↗
PubMed2000

p53 splice acceptor site mutation and increased HsRAD51 protein expression in Bloom's syndrome GM1492 fibroblasts.

GM1492 human diploid skin fibroblasts derived from a patient with Bloom's syndrome (BS), lack detectable p53 mRNA and protein as shown by Northern and Western blotting, and express an increased RecA-like activity. Here we demonstrate that the p53 gene is grossly intact in GM1492 cells according to Southern blotting. DNA sequencing did not reveal any mutations in the promoter region of p53. A highly sensitive RT-PCR produced a p53 cDNA fragment that was shorter than expected. DNA sequence analysis of p53 cDNA showed that exon 6 was missing, explaining the shorter PCR product. Furthermore, sequencing of genomic DNA revealed a base substitution at the nucleotide preceding the AG splice acceptor site of intron 5. The omission of exon 6 creates a frameshift at the junction of exons 5 and 7, and a premature stop codon in exon 7. The aberrant transcript is predicted to encode a truncated p53 protein containing 189 amino acid residues. Moreover, Western blotting demonstrated elevated HsRAD51 protein levels in GM1492 cells. The lack of sufficient levels of wild-type p53 and increased levels of HsRad51 protein may contribute to the elevated RecA-like activity in the GM1492 fibroblasts.

Alternative Splicing↗
PubMed2000

Consequences of cell death: exposure to necrotic tumor cells, but not primary tissue cells or apoptotic cells, induces the maturation of immunostimulatory dendritic cells.

Cell death by necrosis is typically associated with inflammation, in contrast to apoptosis. We have identified additional distinctions between the two types of death that occur at the level of dendritic cells (DCs) and which influence the induction of immunity. DCs must undergo changes termed maturation to act as potent antigen-presenting cells. Here, we investigated whether exposure to apoptotic or necrotic cells affected DC maturation. We found that immature DCs efficiently phagocytose a variety of apoptotic and necrotic tumor cells. However, only exposure to the latter induces maturation. The mature DCs express high levels of the DC-restricted markers CD83 and lysosome-associated membrane glycoprotein (DC-LAMP) and the costimulatory molecules CD40 and CD86. Furthermore, they develop into powerful stimulators of both CD4(+) and CD8(+) T cells. Cross-presentation of antigens to CD8(+) T cells occurs after uptake of apoptotic cells. We demonstrate here that optimal cross-presentation of antigens from tumor cells requires two steps: phagocytosis of apoptotic cells by immature DCs, which provides antigenic peptides for major histocompatibility complex class I and class II presentation, and a maturation signal that is delivered by exposure to necrotic tumor cells, their supernatants, or standard maturation stimuli, e.g., monocyte-conditioned medium. Thus, DCs are able to distinguish two types of tumor cell death, with necrosis providing a control that is critical for the initiation of immunity.

Animals↗
PubMed2000

Expression profile viewer (ExProView): a software tool for transcriptome analysis.

A software tool, Expression Profile Viewer (ExProView), for analysis of gene expression profiles derived from expressed sequence tags (ESTs) and SAGE (serial analysis of gene expression) is presented. The software visualizes a complete set of classified transcript data in a two-dimensional array of dots, a "virtual chip," in which each dot represents a known gene as characterized in the transcript databases Expressed Gene Anatomy Database or UniGene. The virtual chip display can be changed between representations of different conceptual systems for gene/protein classification and grouping. Four alternative projections are currently available: (i) cellular role, (ii) subcellular compartment, (iii) chromosome localization, and (iv) total UniGene display. However, the chip can be adapted to any other desired layout. By selecting dots, further information about the represented genes is obtained from the local database and WWW links. The software thus provides a visualization of global mRNA expression at the descriptive level and guides in the exploration of patterns of functional expression, while maintaining direct access to detailed information on each individual gene. To evaluate the software, public EST and SAGE gene expression data obtained from the Cancer Genome Anatomy Project at the National Center for Biotechnology Information were analyzed and visualized. A demonstration of the software is available at http://www.biochem.kth. se/exproview/.

Data Display↗
PubMed2000

Transient isotachophoresis for sensitivity enhancement in capillary electrophoresis-mass spectrometry for peptide analysis.

Transient isotachophoresic (ITP) focusing was used for the on-line analysis of peptides by capillary zone electrophoresis-mass spectrometry (CZE-MS), allowing injection volumes of up to 0.9 microL. A sheath liquid electrospray interface was used with a single quadrupole mass analyzer. First, the technique was applied to the qualitative analysis of a tryptic digest of cytochrome c, resulting in low-background, high-quality spectra. Second, the linear range was investigated by selected ion monitoring (SIM) for a peptidomimetic direct thrombin inhibitor melagatran (Mr 429.5) and two endogenous peptides, substance P (Mr 1348) and calcitonin gene-related peptide (alpha-CGRP; Mr 3806).

Electrophoresis, Capillary↗
PubMed2000

Olfactory functions are mediated by parallel and hierarchical processing.

How the human brain processes the perception, discrimination, and recognition of odors has not been systematically explored. Cerebral activations were therefore studied with PET during five different olfactory tasks: monorhinal smelling of odorless air (AS), single odors (OS), discrimination of odor intensity (OD-i), discrimination of odor quality (OD-q), and odor recognition memory (OM). OS activated amygdala-piriform, orbitofrontal, insular, and cingulate cortices and right thalamus. OD-i and OD-q both engaged left insula and right cerebellum. OD-q also involved other areas, including right caudate and subiculum. OM did not activate the insula, but instead, the piriform cortex. With the exception of caudate and subiculum, it shared the remaining activations with the OD-q, and engaged, in addition, the temporal and parietal cortices. These findings indicate that olfactory functions are organized in a parallel and hierarchical manner.

Adult↗
PubMed2000

Volatile compounds in the production of liquid beet sugar.

Samples from different parts of a beet sugar factory and refinery were analyzed with respect to volatile compounds by means of liquid-liquid extraction followed by gas chromatography-mass spectrometry (GC-MS). A limited number of the samples were analyzed by means of gas phase extraction (headspace) followed by GC-MS. Selected compounds were followed through the sugar manufacturing process. The behavior of different compounds varied greatly throughout the process, with some compounds such as geosmin (trans-1, 10-dimethyl-trans-9-decalol), dimethyl disulfide, and propionic and hexanoic acid present at the beginning of the process but disappearing rapidly after further processing. Other compounds, such as indole, dihydrobenzofuran, and 2-phenylethanol, were not detected at the start of the process but were formed later on and removed in the final product. In the final product, three pyrazines remained at fairly low concentrations, together with 3-methylcyclopentadione, ethylhexanol, and methyl pyrrole ketone.

Carbohydrates↗
PubMed2000

Recombination of simple molecular ions studied in storage ring: dissociative recombination of H2O+

Dissociative recombination of vibrationally relaxed H2O+ ions with electrons has been studied in the heavy-ion storage ring CRYRING. Absolute cross-sections have been measured for collision energies between 0 eV and 30 eV. The energy dependence of the cross-section below 0.1 eV is found to be much steeper than the E-1 behaviour associated with the dominance of the direct recombination mechanism. Resonant structures found at 4 eV and 11 eV have been attributed to the electron capture to Rydberg states converging to electronically excited ionic states. Complete branching fractions for all dissociation channels have been measured at a collision energy of 0 eV. The dissociation process is dominated by three-body H + H + O breakup that occurs with a branching ratio of 0.71.

Journal Article↗
PubMed2000

Organising habilitation services: team structures and family participation.

This study is part of a project focusing on co-operation between receivers of habilitation services (families) and professionals. The study focuses on the organisation and co-ordination of the services, and compares two structures for their accomplishment. The first is the typical multiprofessional habilitation team (MHT), and the second is the individualised team (ISP). MHT teams are organised within the habilitation agency, while ISP teams span institutional boundaries. An ISP team is formed around the individual child who receives services from the habilitation centre, and includes parents (sometimes the child), professionals from the habilitation centre, and professionals from other service-providing institutions that are actively involved (for instance pre-school teacher, schoolteacher etc.). The team maps child and family needs, organises assessments and services and formulates goals that subsequently are monitored and followed up. A questionnaire (Measures of Processes of Care) was used to assess the experiences of 385 service receivers. The questionnaire focuses on service receivers' experiences of the family-centredness of the service, operationalised in 56 items, along with five items concerning perceptions of level of control over service provision. The experiences of families having individualised teams were compared to those not having these teams. Significant differences were obtained, suggesting the impact of the form of service organisation on the content. Families having ISP teams report both more family-centred service, and a greater level of control over service provision. Results are discussed in terms of organising structures and co-ordination of services, and in terms of family participation.

Adolescent↗