Biomedical subjects

P Thygesen

Publications and source records attributed to P Thygesen.

At least 19 recordsLinked to original sources

PubMed2003

Investigation of the adjuvant and immuno-suppressive effects of benzyl butyl phthalate, phthalic acid and benzyl alcohol in a murine injection model.

In a recent study, di-(2-ethylhexyl) phthalate (DEHP) and its metabolite, mono-2-ethylhexyl phthalate, were shown to possess adjuvant effect [Toxicology 169 (2001) 37; Toxicology Letters 125 (2001) 11]. The present study investigates the adjuvant effect of another important commercial phthalate plasticizer, benzyl butyl phthalate (BBP) as well as its degradation products, phthalic acid and benzyl alcohol (BA) in a murine model. The model antigen, ovalbumin (OA), was injected either alone (OA control group), together with one of the test substances (test group) or together with aluminium hydroxide, which served as the positive adjuvant control. The mice were boosted either once or twice with OA before blood was collected and assayed for the content of OA-specific IgE, IgG1 and IgG2a antibodies by ELISA methods. Adjuvant effect was defined as a statistically significant increased antibody level in the test groups compared with the OA control group. Conversely, if the antibody production in a test group was significantly lower than the OA control group, it was deemed to be immunosuppression. This study demonstrated that BBP, in contrast to DEHP, did not possess adjuvant effect. Furthermore, immunosuppression was apparent in the case of BA. The study also demonstrated that if the injections give rise to formation of wounds, it may cause false positive results.

Adjuvants, Immunologic↗

PubMed2001

Di-(2-ethylhexyl) phthalate possesses an adjuvant effect in a subcutaneous injection model with BALB/c mice.

The prevalence of allergic airway diseases is rapidly increasing in Western Europe and North America and the introduction of anthropogenic chemicals may explain a part of this increase. Recently, our group found that degradation products from several commonly used phthalate plasticizers possess adjuvant activity in an animal model. Mono-2-ethylhexyl phthalate, which is the degradation product of di-(2-ethylhexyl) phthalate (DEHP), was among these substances. These findings prompted the study of the adjuvant activity of the parent compound itself. Thus, DEHP was studied in a model using ovalbumin (OA) as the model antigen. OA was injected subcutaneously in the neck region of BALB/cJ mice with or without DEHP. The levels of OA-specific IgE, IgG1 and IgG2a antibodies in sera were measured by ELISA. Adjuvant effect, defined as a statistically significant increase in antibody level, was observed with IgG1 at a concentration of 2000 microg DEHP/ml after both one and two boosters.

Adjuvants, Immunologic↗

PubMed2001

Adjuvant and immuno-suppressive effect of six monophthalates in a subcutaneous injection model with BALB/c mice.

The prevalence of allergic airway diseases is rapidly increasing in Western Europe and North America. This increase in disease prevalence may be associated with environmental pollutants. The present study investigated the adjuvant and immuno-suppressive effect of a series of monophthalates which are considered to be important metabolites of commonly used phthalate plasticizers. The effects were studied in a screening model. Ovalbumin (OA), used as the model antigen, was injected subcutaneously in the neck region of BALB/cJ mice with or without one of the test substances, mono-n-butyl phthalate (MnBP), monobenzyl phthalate (MBnP), mono-n-octyl phthalate (MnOP), mono-2-ethylhexyl phthalate (MEHP), mono-iso-nonyl phthalate (MiNP) or mono-iso-decyl phthalate (MiDP). The levels of OA-specific IgE, IgG1 and IgG2a in sera were measured by ELISA. Immuno-suppressive effect, defined as a statistically significant reduction in IgE or IgG1 antibody production, was observed with MEHP (1000 microg/ml, IgE and IgG1), MnOP (1000 microg/ml, IgE and IgG1), MiNP (1000 microg/ml, IgE and 10 microg/ml, IgG1) and MiDP (100 microg/ml, IgE and IgG1). Adjuvant effect, defined as a statistically significant increase in IgE or IgG1 antibody level, occurred with MEHP (10 microg/ml, IgE), MnOP (100 microg/ml, and 10 microg/ml, IgG1) and MiNP (100 microg/ml, IgE). No statistically significant immune modulating effect was seen with MBnP and MnBP.

Adjuvants, Immunologic↗

PubMed2000

Histologic, cytologic, and bacteriologic examinations of experimentally induced Salmonella typhimurium infection in Lewis rats.

BACKGROUND AND PURPOSE: Histopathologic changes, cellular composition, and bacterial spreading were studied in rat spleen after experimentally induced infection with Salmonella typhimurium. METHODS: Lewis rats were inoculated intraperitoneally with 10(6) bacteria. Spleen weight, cell numbers, and cell surface markers were studied together with histopathologic changes, and expression of inducible nitric oxide synthase (iNOS). The spread of bacteria to blood, spleen, liver, mesenteric lymph nodes, lung, and kidney was studied at 12 hours, and 1, 3, 7, 14, and 28 days after inoculation. RESULTS: Experimentally induced infection caused an increase in spleen weight and leukocyte numbers, and a decrease in CD49d, on postinoculation days (PID) 3 through 7. Numerous granulomas were disseminated throughout the splenic red pulp also on PID 3 through 7. From PID 14 on, clearance of cellular exudate and regeneration of tissue structure were observed. Massive expression of iNOS was seen on PID 3. Bacterial growth was observed in liver and spleen from 12 hours to 14 days after inoculation. Bacteria were detected in blood on PID 3 and mesenteric lymph nodes were infected from PID 3 through 14. CONCLUSIONS: Salmonella typhimurium was rapidly taken up by the reticuloendothelial system. The infection induced weight increase and reversible changes in the spleen, peaking on PID 3 with granuloma formation and infiltration with macrophages. On PID 3, extensive production of iNOS within the granulomas was observed, suggesting initial killing of phagocytosed bacteria, followed by bacterial clearance and tissue regeneration. Cell surface marker expression on CD4+ T cells indicated no change in their numbers; however, there was a time-dependent change in expression of CD49d.

Animals↗

PubMed1999

Genes for human arylamine N-acetyltransferases in relation to loss of the short arm of chromosome 8 in bladder cancer.

Polymorphisms of N-acetyltransferase type 2 (NAT2) conferring the slow acetylator phenotype have been linked to increased susceptibility to arylamine-induced bladder cancer in Caucasians. Genes for NAT2, the other NAT isozyme, NAT1, and a NAT pseudogene (NATP) are found on 8p22, a region displaying loss of heterozygosity, particularly in invasive bladder tumours. A restriction enzyme digestion map has defined the relative positions of the NAT genes to each other and to adjacent CpG islands. NAT2, as a polymorphic gene of known function, is a potentially valuable marker for the detection of loss of heterozygosity in 8p22. Two approaches to investigate loss of heterozygosity at the NAT2 locus in bladder tumours have been used. (1) A cosmid containing NAT2 has been used in fluorescence in-situ hybridization on human exfoliated bladder cells collected from unselected bladder cancer outpatients. Loss of signal from the NAT2 cosmid was found in nine of the 20 patients. (2) A panel of 13 human bladder tumours was investigated for loss of heterozygosity using the polymorphism in the NAT2 gene as a marker. Loss of heterozygosity at the NAT2 locus has been compared with loss of heterozygosity at adjacent microsatellite marker sites known to be located on 8p. There is agreement between loss of heterozygosity at the NAT2 locus and adjacent microsatellite marker loci in 11 of the tumours but two of the tumours appear to show retention at the NAT2 locus. More extensive mapping of the region around the NAT loci, particularly on the centromeric side, is important to pinpoint possible tumour suppressor genes or their modifiers in the region. There are no other expressed sequences known in this region and therefore NAT genes are important genetic landmarks.

Arylamine N-Acetyltransferase↗

PubMed1997

Transfer of primed CD4+OX40- T lymphocytes induces increased immunity to experimental Salmonella typhimurium infections in rats.

The protective effect of primed CD4 T cells against a lethal dose of Salmonella typhimurium was studied in Lewis rats. Primed CD4 T cells were obtained by inoculating Lewis rats with a non-lethal dose of S. typhimurium. Four weeks after the infection, spleen non-adherent mononuclear cells were isolated. The cells were separated according to their expression of CD4 and the OX40 antigen by FACS. OX40+ and OX40- CD4+ T-cell subpopulations were together with unsorted CD4+ T cells transferred to untreated rats 24 h prior to infection with S. typhimurium. Transfer of either unsorted CD4+ T cells or CD4+ T cells sorted into OX40- or OX40- subpopulations significantly increased animal survival compared to controls. Animals receiving OX40+CD4+ T cells did not differ significantly in survival probability from those receiving unsorted CD+ T cells. However, animals receiving OX40-CD4+ T cells had a significantly better survival compared to animals given unsorted CD4+ T cells. It is concluded that OX40-CD4+ T cells can induce significant protection against S. typhimurium infections in rats. This is most likely due to the fact that the OX40-CD4+ T-cell population contains a significant number of antigen-specific memory T cells that have returned to a resting state.

Animals↗

PubMed1997

Mapping AAC1, AAC2 and AACP, the genes for arylamine N-acetyltransferases, carcinogen metabolising enzymes on human chromosome 8p22, a region frequently deleted in tumours.

Arylamine N-acetyltransferases (NATs) are encoded at two loci on 8p22, a region subject to deletions in bladder tumours. The two functional genes (AAC1 and AAC2 alias NAT1 and NAT2) without introns in the coding region, encode enzymes which metabolise carcinogens, including bladder carcinogens. They are both multi-allelic and certain alleles have been implicated as susceptibility factors in bladder cancer. There is a third N-acetyltransferase gene, a pseudogene, AACP alias NATP, which we show is also located on chromosome 8 at the p22 region. We have mapped a series of YAC clones (ICI and CEPH) containing the NAT genes and the markers D8S21, an RFLP marker, and D8S261, a microsatellite marker. We show that D8S21 is a portion of the coding region of AAC2. The order of genes in this region, covering some 2 Mb, is TEL-D8S261-AAC1-AACP-AAC2 (D8S21)-CEN. The restriction map also illustrates that there are likely to be other expressed genes in the region through the identification of CpG islands.

Arylamine N-Acetyltransferase↗

PubMed1996

Immunity to experimental Salmonella typhimurium infections in rats. Transfer of immunity with primed CD45RC+ and CD45RC- CD4 T-cell subpopulations.

The protective effect of primed CD4 T cells against a lethal dose of Salmonella typhimurium was studied in Lewis rats. Primed CD4 T cells were obtained by inoculating Lewis rats with a non-lethal dose of S. typhimurium. Four weeks after the infection, spleen CD4 T cells were separated by antibody-coated magnetic microspheres using an antibody against the CD4 molecule (W3/25). The cells were separated according to their expression of the CD45RC isoform of the leukocyte common antigen by FACS. CD45RC+ and CD45RC- CD4 T-cell subpopulations were transferred to untreated rats 24 h prior to infection with S. typhimurium. Transfer of CD45RC+ and CD45RC- CD4 T cells induced a significant survival, p = 0.022 and p = 0.023 respectively, following inoculation with S. typhimurium compared to animals with no cells transferred. The infection induced an increase in CD4 T cells expressing the CD45RC isoform compared to untreated controls (p < 0.001). It is concluded that both CD45RC+ and CD45RC- cells can induce a significant protection against S. typhimurium infections in rats. Therefore the CD45RC antigen cannot be used as a phenotypic marker for functionally distinct CD4 T-cell subpopulations. The infection-induced increase in CD45RC+ cells is most likely due to generation of antigen-specific memory T cells.

Animals↗

PubMed1995

Xenogenetics in multifactorial disease susceptibility.

Susceptibility to multifactorial disease includes both genetic and environmental components. These two aspects of susceptibility are interlinked through genetic control of an individual's response to the environment. As a first step in identifying disease susceptibility genes that influence the response of an individual to foreign compounds (xenobiotics), it is necessary to study disorders in which there is an identified environmental trigger. Establishing a DNA resource from individuals with known environmental exposure ('a xenogenetic register') for diseases with an established environmental aetiology is an essential step in beginning to understand how environmental factors contribute to the susceptibility to polygenic diseases. A complementary approach to identification of environmental factors is suggested using a comparison of genetically homogeneous subdivisions of individuals with polygenic diseases where there is no clue to the environmental trigger.

Animals↗

PubMed1994

Immunity to experimental Salmonella typhimurium infections in rats. Transfer of immunity with primed CD4+CD25high and CD4+CD25low T lymphocytes.

The protective effect of primed CD4+ T lymphocytes against a lethal dose of 10(8) viable Salmonella typhimurium was studied in Lewis rats. Primed CD4+ T lymphocytes were obtained by inoculating Lewis rats with a non-lethal dose of 10(6) viable S. typhimurium. Four weeks after the infection, spleen CD4+ T lymphocytes were separated using magnetic microspheres coated with an antibody against the CD4 molecule (W3/25). Subsequent sorting into activated and non-activated subpopulations using the p55 alpha-chain of the interleukin-2 receptor (CD25) as an activation marker was performed by a fluorescence-activated cell sorter. Untreated Lewis rats were injected with 10(4) different primed CD4+ T-cell populations 24 h prior to the lethal dose of 10(8) viable S. typhimurium. Blood samples were drawn from the orbital plexus 1, 2, 3, and 4 weeks after the infection, and analysed for specific IgM and IgG antibodies. Cell sorting revealed that 2/3 of the primed CD4+ T lymphocytes expressed high levels of CD25. Cell transfer revealed that both CD25high and CD25low expression populations could induce immunity against a lethal dose of S. typhimurium, whilst antibody analysis revealed that antibody levels were not correlated with protection against S. typhimurium infections, although it showed that a higher and more persistent level of specific IgG antibodies was produced in animals receiving the CD4+CD25high fraction. It is concluded that 10(4) primed CD4+ T lymphocytes can induce immunity in animals challenged with a lethal dose of S. typhimurium and that antibodies do not seem to be correlated with the immunity induced. The CD4+CD25high fraction was, however, associated with a higher and more persistent level of specific IgG antibodies.

Animals↗

PubMed1992

Effect of immunosuppressive agents on the guanethidine-induced sympathectomy in athymic and euthymic rats.

Guanethidine sulphate causes destruction of peripheral sympathetic neurons and infiltration of mononuclear inflammatory cells in the sympathetic ganglia of both athymic nude (rnu/rnu) and euthymic LEW/Mol rats. The effect of guanethidine is believed to be an autoimmune reaction. To determine the effect of immunosuppressive drugs concurrently with guanethidine treatment both athymic and euthymic rats were treated with guanethidine 40 mg/kg i.p. daily for 14 days, cyclophosphamide 100 mg/kg i.p. on days 1 and 8, methylprednisolone 10 mg/kg and cyclosporin A 10 mg/kg daily from days 1 to 7, and then every other day from days 8 to 14. The number of neurons in the sympathetic ganglia was counted and four subpopulations of mononuclear inflammatory cells were identified by monoclonal antibodies MHC II, CD8 T-cells/NK-cells, CD5 T-cells, CD4 T-cells/macrophages. Our results show that the immunosuppressive drugs used were unable to prevent the guanethidine-induced reduction of sympathetic neurons, although the number, of neurons following guanethidine-methylprednisolone treatment was significantly higher compared with guanethidine alone in both athymic and euthymic rats. The identification of mononuclear cells in the sympathetic ganglia showed that the CD8/NK and CD5 populations were the populations primarily responding to guanethidine treatment. Both CD8/NK and CD5 populations were absent without guanethidine, but increased significantly following guanethidine in both athymic and euthymic animals. None of the immunosuppressive drugs used could prevent the guanethidine-induced rise in the CD8/NK population in neither athymic nor in euthymic rats. The rise in the CD5 population was suppressed following treatment with all immunosuppressive drugs in athymic rats, but only following methylprednisolone in euthymic animals. These results indicate that guanethidine induces proliferation of T-cells in euthymic rats and non-functional CD5 positive pre T-cells in athymic animals. The CD5 population in both athymic and euthymic animals appears relatively more sensitive to immunosuppressive drugs than the NK-cell population also activated by guanethidine. This relatively resistant NK-cell population seems to play an important role in the guanethidine-induced destruction of sympathetic neurons and can explain why the guanethidine-induced immunological reaction could not be fully prevented by the immunosuppressive drugs used. The conclusion is that guanethidine induces destruction of sympathetic neurons by a NK-cell-mediated reaction.

Animals↗

PubMed1992

Athymic experimental animals in pharmaco-immunological research.

Immunodeficient animals--the nude mouse and the nude rat--allow studies of drug action and possible side effects without interference from the immune system. Comparative investigations in athymic and euthymic animals allowed us to elucidate the role of T-lymphocytes in the pathogenesis of streptozotocin-induced diabetes mellitus in mice, and the importance of NK-cells as effectors in guanethidine-induced sympathectomy in the rat. It is suggested that immunodeficient animals should be included in toxicological studies of xenobiotics.

Animals↗

PubMed1992

Anti-asialo GM1 antibodies prevents guanethidine-induced sympathectomy in athymic rats.

Guanethidine sulphate induces destruction of peripheral sympathetic neurons and infiltration of mononuclear cells in rat sympathetic ganglia. The effect of guanethidine is believed to be an autoimmune reaction. In order to determine the effect of anti-asialo GM1, an antibody that binds to the glycolipid asialo GM1 expressed on rodent natural killer cells, athymic Lewis rats received guanethidine 40 mg/kg i.p. daily from day 1 to 14 and anti-asialo GM1 i.p. 1 mg/rat on day -2, 0, 2, 6, and 10 in the study period. Saline and anti-asialo GM1 were given alone in the same doses as control. The number of neurons in the sympathetic ganglia were counted and the ganglionic volume determined. The presence of natural killer cells in the ganglia were determined by immunohistochemical methods. Our results shows that anti-asialo GM1 can prevent guanethidine-induced reduction of sympathetic neurons, but not prevent the initiation of an immunological reaction in the ganglia. Natural killer cells could only be identified in ganglia following guanethidine treatment alone. It is concluded that anti-asialo GM1 treatment can prevent the guanethidine-induced sympathectomy by eliminating the natural killer cells from the ganglia.

Animals↗

PubMed1990

Identification of the mononuclear cell infiltrate in the superior cervical ganglion of athymic nude and euthymic rats after guanethidine-induced sympathectomy.

Guanethidine sulphate 40 mg/kg intraperitoneally for 14 days induced chromatolysis and nerve cell death in the superior cervical ganglia of athymic nude (rnu/rnu) LEW/Mol rats and their euthymic (+/rnu) LEW/Mol heterozygous littermates. Histologically the sympathetic ganglia were dominated by an infiltration of small inflammatory cells. By means of monoclonal antibodies these cells were identified. The number of B-lymphocytes increased following guanethidine in both athymic and euthymic rats. The number of T-lymphocytes increased to a great extent in euthymic rats, but was virtually missing in athymic rats. The number of NK-cells and monocytes/macrophages increased in both athymic and euthymic rats. The conclusion is, that guanethidine exerts a direct effect on sympathetic ganglion cells followed by a thymus-independent immune response.

Animals↗

PubMed1980