Biomedical subjects

Gunnar Nilsson

Publications and source records attributed to Gunnar Nilsson.

32 records · Page 2Linked to original sources

PubMed2003

Gene expression profile by blocking the SYT-SSX fusion gene in synovial sarcoma cells. Identification of XRCC4 as a putative SYT-SSX target gene.

Increasing evidence suggests that the SYT-SSX fusion gene plays an important role in synovial sarcoma development and progression. However, very little is known about the downstream targets of SYT-SSX. In this study, we used antisense oligonucleotides to block the expression of the SYT-SSX fusion gene in synovial sarcoma cells. By comparing SYT-SSX inhibited cells with noninhibited cells, the gene expression profile was analysed using cDNA microarray and established by real-time PCR. Herewith, using a filter containing 1176 cancer-relevant genes, we found that the DNA repair gene XRCC4 and the DNA mismatch repair gene MSH2 were downregulated, whereas the gene encoding for the serine/threonine protein kinase PRK (also known as CNK), and the macrophage inhibitory cytokine MICI (also known as PLAB) were upregulated after the inhibition of SYT-SSX. In comparison, expression of the XRCC4 gene was undergoing the strongest alteration. Consistently, the protein expression of XRCC4 was found to be decreased after SYT-SSX inhibition, whereas there were no detectable changes for the other gene products. Our study provides some clues to elucidate the signaling pathways of the SYT-SSX fusion gene, as well as it demonstrates a valuable model system for search for other SYT-SSX targets.

DNA-Binding Proteins↗

PubMed2003

Characteristic sequence motifs located at the genomic breakpoints of the translocation t(X;18) in synovial sarcomas.

The SYT-SSXI and SYT-SSX2 fusion genes, derived by reciprocal translocations t(X;18), are acquired genetic events strongly associated with the tumorigenesis of synovial sarcoma. In approaching the mechanisms underlying the formation of these fusion oncogenes, we have analysed the genomic sequences surrounding the SYT-SSX breakpoints in 10 tumors, two expressing SYT-SSXI and eight expressing SYT-SSX2 fusion transcripts. The breakpoints were found to be clustered in the 5' end of intron 10 of SYT, and in two cluster regions within intron 4 of SSX2, whereas the two breakpoints in SSX1 intron 4 were 0.5 kb apart. SYT intron 10 is abundant in repetitive regions with the interspersed repeats occupying 66% of the whole intron. Nine of the 10 breakpoints in intron 10 of SYT and six of the eight breakpoints in intron 4 of SSX2 were at or near repetitive regions. These findings suggest that repetitive regions may contribute to the distribution of genomic breakpoints. Several of the fusion sequences exhibited characteristic signs of nonhomologous end joining, including microhomologies at the end points as well as deletions. Sequences highly homologous (83-94%) to consensus topoisomerase II cleavage sites were identified at or near the breakpoints in all 10 tumors, suggesting a role of this enzyme in creating staggered ends at the breakpoint. Furthermore, sequences highly homologous to consensus Translin binding sequences were found at the breakpoints in two cases, and an Alu-Alu fusion and an insertion of a 206-bp LINE-1 element were found at the breakpoint in one case each. The demonstration of characteristic sequences at the SYT-SSX breakpoint regions is expected to improve our understanding of the molecular genetic mechanisms behind translocations in general, and of the SYT-SSX fusions in synovial sarcoma in particular.

Artificial Gene Fusion↗

PubMed2003

Mast cell survival and apoptosis in organ-cultured human skin.

Mast cells accumulate and persist predominantly in the upper dermis of the skin but the mechanism for this is obscure. The skin is normally exposed to external air, which is essential for the maturation of the epidermis and probably also the dermis. In order to clarify the importance of air exposure on dermal mast cells, skin organ culture at the air-liquid interface (ALI) and submerged (SM) in medium (10% fetal calf serum and Dulbecco's modification of Eagle's medium) was used to study changes in tryptase-, chymase- and Kit-positive mast cell numbers during cultivation for up to 14 days. In addition, possible apoptosis (TACS TdT in situ apoptosis detection method) in chymase-positive mast cells was studied during the culture. In the less-physiologic SM culture, the number of Kit-positive mast cells decreased rapidly on day 1-2 and tryptase-positive cells decreased markedly on day 14. This decrease in mast cell numbers can be explained by the finding that a rapid increase in the apoptosis index of mast cells was induced on day 1-2. In contrast, in the more physiologic ALI culture, the number of Kit-positive cells was sustained over 1-2 days but then decreased on day 7. In addition, tryptase-positive cells decreased steadily in number but not to the same extent as those in the SM culture. Moreover, the increase in the apoptosis index of mast cells was delayed until day 7 in the ALI culture. Addition of exogenous stem cell factor (up to 200 ng/ml) to the SM culture could not prevent the decay in tryptase- and chymase-positive cells. However, stem cell factor reduced significantly the number of Kit-positive cells already on day 2 indicating that the cells had responded. Addition of histamine (0.25 or 1 mM) or tumor necrosis factor-alpha (500 or 2000 U/ml) caused a decrease in the number of tryptase- and Kit-positive cells in the SM culture. In conclusion, a novel finding was that air exposure in the ALI culture markedly delayed the rapid apoptosis and subsequent decrease in mast cell numbers noted to occur in the SM culture. Stem cell factor could not prevent the rapid decrease in mast cell numbers. Histamine and tumor necrosis factor-alpha are possible factors promoting the decline in mast cells.

Air↗

PubMed2003

Functional and phenotypic studies of two variants of a human mast cell line with a distinct set of mutations in the c-kit proto-oncogene.

The human mast cell line (HMC)-1 cell line is growth-factor independent because of a constitutive activity of the receptor tyrosine kinase Kit. Such deregulated Kit activity has also been suggested causative in gastrointestinal stromal tumours (GISTs) and mastocytosis. HMC-1 is the only established continuously growing human mast cell line and has therefore been widely employed for in vitro studies of human mast cell biology. In this paper we describe two sublines of HMC-1, named HMC-1(560 ) and HMC-1(560,816 ), with different phenotypes and designated by the locations of specific mutations in the c-kit proto-oncogene. Activating mutations in the Kit receptor were characterized using the pyrosequencing trade mark method. Both sublines have a heterozygous T to G mutation at codon 560 in the juxtamembrane region of the c-kit gene causing an amino acid substitution of Gly-560 for Val. In contrast, only HMC-1(560,816) cells have the c-kitV816 mutation found in mast cell neoplasms causing an Asp-->Val substitution in the intracellular kinase domain. Kit was constitutively phosphorylated on tyrosine residues and associated with phosphatidylinositol 3'-kinase (PI 3-kinase) in both variants of HMC-1, but this did not lead to a constitutive phosphorylation of Akt or extracellular regulated protein kinase (ERK), which are signalling molecules normally activated by the interaction of stem cell factor (SCF) with Kit. The documentation and characterization of two sublines of HMC-1 cells provides both information on the biological consequences of mutations in Kit and recognition of the availability of what in reality are two distinct cultured human mast cell lines.

Cell Culture Techniques↗

PubMed2003

Retinoic acid inhibits in vitro development of mast cells but has no marked effect on mature human skin tryptase- and chymase-positive mast cells.

Stem cell factor plays a key role in the development of human mast cells via interaction with Kit receptor. We and other groups have previously shown that a number of cytokines can regulate the stem-cell-factor-dependent development of mast cells in vitro. In this study we investigated the effect of retinoic acid on human mast cells in vitro and in vivo. Retinoids are known to have strong modulatory effects on hematopoietic differentiation. We found that all-trans-retinoic acid, at concentrations as low as 1 nM, inhibits the stem-cell-factor-dependent differentiation of mast cells in vitro. This effect of retinoic acid was found to be on progenitor cells, whereas more mature mast cells were less affected. The use of specific agonists binding either to the RAR or the RXR nuclear receptors indicated involvement of both the RAR/RXR and RXR/RXR pathways in inhibiting mast cell differentiation. In contrast to the effects on mast cell progenitors, retinoic acid had no effect on the number of mature mast cells in skin organ cultures. Furthermore, topical treatment of normal skin with a retinoic-acid-containing cream caused an increase in the number of tryptase-positive mast cells, whereas the numbers of the major cutaneous mast cell type, tryptase- and chymase-positive mast cells, remained unaffected. Our results suggest that retinoic acid suppresses commitment of progenitor cells into the mast cell lineage and/or acts on early mast cell progenitors, whereas mature cutaneous mast cells are less susceptible to retinoic acid.

Antineoplastic Agents↗

PubMed2003

Textual content, health problems and diagnostic codes in electronic patient records in general practice.

OBJECTIVE: To investigate textual content, health problems and diagnostic codes in everyday electronic patient records. DESIGN: Retrospective and observational database study. SETTING: Primary health care in Stockholm. SUBJECTS: Twenty randomly selected general practitioners with 20 records each. MAIN OUTCOME MEASURES: The frequency of use of problem-oriented medical records. The number of words, problems and diagnostic codes. The completeness and correctness of the diagnostic codes. RESULTS: About 14.5% of 400 studied records were problem-oriented. The mean number of words per record was 99.4, and the mean number of problems managed per record was 1.2. On average, there were 1.1 diagnostic codes per record and this differed widely among GPs and also among the electronic patient record systems. The mean number of codes per problem was 0.9, and the proportion of correct codes was 97.4%. CONCLUSIONS: The electronic patient records in general practice in Stockholm have an extensive textual content. A vast majority of the problems are coded and the completeness and correctness of diagnostic codes are high. It seems that problem-oriented electronic patient record systems enforce coding activities. It is feasible to establish a database of diagnostic data for research and health care planning based on electronic patient records.

Disease↗

PubMed2003

Histidine decarboxylase, a pyridoxal phosphate-dependent enzyme, is an autoantigen of gastric enterochromaffin-like cells.

Patients with autoimmune polyendocrine syndrome type 1 often have autoantibodies against neurotransmitter synthesizing enzymes, including the pyridoxal phosphate-dependent enzymes glutamic acid decarboxylase and aromatic L-amino acid decarboxylase. Using a candidate approach, we have identified the histamine-synthesizing enzyme histidine decarboxylase, also pyridoxal phosphate dependent, as an autoantigen in this disorder. Anti-histidine decarboxylase antibodies reacting with in vitro translated antigen were found in 36/97 (37%) of autoimmune polyendocrine syndrome type 1 patients studied. The antibodies also reacted with the native enzyme in HMC-1 cell lysates and did not cross-react with the highly homologous aromatic L-amino acid decarboxylase. Anti-histidine decarboxylase antibodies were associated with a history of intestinal dysfunction (P = 0.017). Gastric and duodenal biopsies from a patient with anti-histidine decarboxylase antibodies were studied by immunohistochemistry. The oxyntic mucosa was found to lack the histamine producing enterochromaffin-like cells, suggestive of an autoimmune destruction. To our knowledge, this is the first report of autoantibodies against histidine decarboxylase and absence of gastric enterochromaffin-like cells.

Adult↗

PubMed2002

Selective CCL5/RANTES-induced mast cell migration through interactions with chemokine receptors CCR1 and CCR4.

Mast cells (MCs) accumulate at sites of allergic mucosal inflammation where they act as central effector and regulatory cells. Because chemokines are of vital importance in directing inflammatory leukocytes to the sites of inflammations, we have investigated the expression and function of CC-chemokine receptor (CCR) on human MCs. Two previously unrecognized MC-chemokine receptors, CCR1 and CCR4, could be identified on cord blood-derived MCs (CBMCs). CCR1 and CCR4 expressed on CBMCs exhibited a unique response profile. Of seven CCR1 and CCR4 agonists tested, only CCL5/RANTES act as an agonist inducing chemotaxis. The migration could be partially blocked by specific antibodies against CCR1 or CCR4, while a complete inhibition was achieved when both CCR1 and CCR4 were blocked. These results demonstrate that both CCR1 and CCR4 are functional receptors on human mast cells with capacity to mediate migration towards CCL5.

Cells, Cultured↗

PubMed2002

The SYT-SSX1 fusion type of synovial sarcoma is associated with increased expression of cyclin A and D1. A link between t(X;18)(p11.2; q11.2) and the cell cycle machinery.

A recent large multi-centre study convincingly confirmed previous observations that the SYT-SSX1 fusion type, compared to SYT-SSX2, of synovial sarcoma is associated with a worse clinical outcome. Apart from the clinical impact, this fact also suggests (1) that the SYT-SSX fusion gene may influence molecular mechanisms involved in tumour growth and progression; and (2) that the SYT-SSX1 fusion type has a stronger influence on these mechanisms than SYT-SSX2. The nature of the underlying mechanisms is, however, still unknown. In this study we made use of the SYT-SSX1 vs SYT-SSX2 concept to investigate whether major, tumour relevant, and growth regulatory proteins (e.g. cyclins and cyclin-dependent kinases) may be involved. Using Western blotting analysis on 74 fresh, fusion variant-typed, tumour samples from localized synovial sarcoma, we found a significant correlation between SYT-SSX1 and high expression of cyclin A (P=0.003) and D1 (P=0.025). Our data suggest that SYT-SSX may influence the cell cycle machinery, and that the more aggressive phenotype of the SYT-SSX1 variant is due to an accelerated tumour cell proliferation.

Cell Cycle↗

PubMed2002

SYT-SSX is critical for cyclin D1 expression in synovial sarcoma cells: a gain of function of the t(X;18)(p11.2;q11.2) translocation.

The SYT-SSX fusion gene has been implicated in the malignant tumor cell growth of synovial sarcoma, but the underlying molecular mechanisms are still poorly understood. Here we demonstrate that SYT-SSX is critical for the protein level of cyclin D1 in synovial sarcoma cells. Antisense oligonucleotides to SYT-SSX mRNA rapidly and drastically decreased cyclin D1 and subsequently inhibited cell growth. This effect is specific for SYT-SSX, without involving the wild-type genes SYT or SSX. The decrease in cyclin D1 expression, which occurred shortly after inhibition of SYT-SSX expression, was found to be primarily dependent on an increased degradation of the cyclin D1 protein, as assessed by pulse-chase experiments using [(35)S]methionine. Furthermore, transfection of mouse fibroblasts with SYT-SSX cDNA increased the stability of cyclin D1. Because treatment with a proteasome inhibitor restored cyclin D1 expression, it seems like SYT-SSX interferes with ubiquitin-dependent degradation of cyclin D1. However, SYT-SSX-regulated cyclin D1 expression was proven to be independent of the glycogen synthetase kinase-3beta pathway. Taken together, our study provides evidence that SYT-SSX stabilizes cyclin D1 and is critical for cyclin D1 expression in synovial sarcoma cells. SYT-SSX-dependent expression of cyclin D1 may be an important mechanism in the development and progression of synovial sarcoma and also raises the possibility for targeted therapy.

3T3 Cells↗

PubMed2002

Human mast cells express two leukotriene C(4) synthase isoenzymes and the CysLT(1) receptor.

Cysteinyl-leukotrienes (cys-LTs) are potent smooth muscle contracting agents, especially in the respiratory tract and microcirculation, and play a key role in inflammatory and allergic diseases. The final step in the biosynthesis of LTC(4), the parent compound of cys-LTs, is catalyzed by a specific GSH transferase termed LTC(4) synthase, which is typically expressed in certain bone marrow-derived cells such as eosinophils and mast cells. Here we report that the human mast cell line HMC-1 as well as human mast cells derived from cord blood (CBMC) express a second enzyme capable of synthesizing leukotriene C(4), i.e., microsomal GSH transferase type 2. Furthermore, these cells abundantly express CysLT(1) receptors that are mostly located at the surface of both types of mast cells, as judged by immunohistochemistry. In addition, stimulation of CBMC with LTC(4) and LTD(4) elicits an immediate and dose-dependent (10(-7)-10(-11) M) mobilization of intracellular Ca(2+), which can be blocked with specific CysLT(1) receptor antagonists. Taken together, our data suggest that human mast cells are equipped with two enzymes that can catalyze the committed step in the biosynthesis of cys-LTs. Moreover, the expression of the cognate receptor CysLT(1) suggests that these lipid mediators may be involved in autocrine signaling pathways regulating mast cell functions.

Animals↗

PubMed2002

Computerisation, coding, data retrieval and related attitudes among Swedish general practitioners-a survey of necessary conditions for a database of diseases and health problems.

OBJECTIVE: To investigate necessary conditions for the establishment of a database of diseases and health problems for research and health care planning, based on electronic patient records in everyday clinical use among general practitioners (GPs). DESIGN: Postal questionnaire study. SETTING: Primary health care in Sweden. SUBJECTS: Three hundred randomly selected GPs. MAIN OUTCOME MEASURES: Degree of computerisation of patient records. User frequency and characteristics of diagnosis classification systems and coding tools. Frequency of coding activities and retrieval of codes, and related attitudes. Opinions on a primary health care version of ICD-10. RESULTS: A total of 184 GPs (61% of the 300 GPs) were included in the study. About 92% used an electronic record system, some type of diagnostic classification was used by 93%, and ICD based classifications by 88%. The classification in use was computerised for 74%. Mainly simple tools were used to retrieve diagnostic codes. About 76% of GPs reported classifying at least one symptom or disease per encounter. The codes were retrieved 'once a month' or more by 19%. Classification of diseases was considered important for follow-up by 83%, and for the care of the patient by 75% of the GPs. The primary health care version of ICD-10 with a total of 972 codes was considered too limited in size by 31%. CONCLUSION: Electronic patient records in everyday clinical use in Swedish general practice provide several fundamentals for a database of diagnostic data. However, there are several barriers to the establishment of such a database that is both valid and reliable.

Analysis of Variance↗

PubMed2002

Mast cell infiltration correlates with poor prognosis in Hodgkin's lymphoma.

Hodgkin's lymphoma (HL) is characterized by a few Hodgkin, Reed-Sternberg cells (HRS) surrounded by benign cells. We recently reported that mast cells were the predominant CD30L-positive cells in HL tumours, and that they activate HRS in vitro through CD30L-CD30 interaction. Here, we investigated the clinical importance of mast cell infiltration in the tumours of 123 patients. Tumour specimens were stained with a mast-cell-specific antibody that detects tryptase. Mast cells were detected in virtually every case and increasing numbers of mast cells correlated to nodular sclerosis histology (P = 0.008). Patients with higher mast cell infiltration had a worse relapse-free survival (P = 0.01).

CD30 Ligand↗

PubMed2002

Management of heart failure in primary health care. A retrospective study on electronic patient records in a registered population.

OBJECTIVE: To study the prevalence, patient characteristics and management of patients with heart failure, and the feasibility of using everyday electronic patient records for research. DESIGN: A 4-year retrospective database study. SETTING: Primary health care in Stockholm. SUBJECTS: Forty-six general practitioners, with a registered population of 100,222 inhabitants. MAIN OUTCOME MEASURES: Number of patients with heart failure, frequencies of their comorbidity, investigations and treatments. RESULTS: Out of the registered population, 667 (0.7%) patients had the diagnosis heart failure and fulfilled the diagnostic criteria in our study, and 98.7% had a comorbidity. The most frequent were ischaemic heart disease (37.2%), hypertension (27.3%), chronic atrial fibrillation (23.7%) and diabetes (22.3%). Major investigations were chest radiograph (66.3%) and echocardiograph (16.9%). Frequent pharmacological treatments were diuretics (90.9%), cardiac glycosides (48.1%), platelet aggregation inhibitors (32.7%), vasodilators (31.6%), angiotensin-converting enzyme inhibitors (27.4%) and beta blockers (14.5%). Diuretics were more frequent for females (p = 0.016) and angiotensin-converting enzyme inhibitors for males (p < 0.001). CONCLUSION: Heart failure was common among the elderly and constituted a complex clinical problem. It seemed that these patients could have been managed more adequately. There were gender differences concerning comorbidity and management. Electronic patient records were feasible for research, although several areas needed improvement.

Aged↗