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Biomedical subjects

J Rygaard

Publications and source records attributed to J Rygaard.

At least 37 records · Page 2Linked to original sources
PubMed1998

Confocal laser scanning microscopy of tumor/vessel relationship in xenografts in nude and scid mice.

Using confocal laser scanning microscopy we studied sections of the T24B, a human bladder carcinoma, grown in C.B.-17 scid/scid or NMRI nu/nu mice in order to examine the relationship between tumor tissue and tumor vessels. Tumor cells were labelled with FITC-anti-cytokeratin and blood vessel endothelia with Cy3-labelled BS-I lectin. In contrast to our expectation, no major leaks in the endothelial lining of blood vessels were observed. We are looking for a suitable marker for mouse lymphatics in order to investigate their possible role.

Animals↗
PubMed1998

Effects of ginseng treatment on neutrophil chemiluminescence and immunoglobulin G subclasses in a rat model of chronic Pseudomonas aeruginosa pneumonia.

Chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) patients is almost impossible to eradicate with antibiotic treatment. In the present study, the effects of treatment with the Chinese herbal medicine ginseng on blood polymorphonuclear leukocyte (PMN) chemiluminescence and serum specific antibody responses were studied in a rat model of chronic P. aeruginosa pneumonia mimicking CF. An aqueous extract of ginseng was administered by subcutaneous injection at a dosage of 25 mg/kg of body weight/day for 2 weeks. Saline was used as a control. Two weeks after the start of ginseng treatment, significantly increased PMN chemiluminescence (P </= 0. 001) and a decreased level in serum of immunoglobulin G (IgG) against P. aeruginosa (P < 0.05) were found. Furthermore, a higher IgG2a level (P < 0.04) but lower IgG1 level (P < 0.04) were found in the ginseng-treated infected group than in the control group. In the ginseng-treated group the macroscopic lung pathology was milder (P = 0.0003) and the percent PMNs in the cells collected by bronchoalveolar lavage was lower (P = 0.0006) than in the control group. However, the alveolar macrophage (AM) chemiluminescence values were not significantly different in the two groups infected with P. aeruginosa. The differences between the ginseng-treated noninfected rats and the control group (without P. aeruginosa lung infection) for the PMN chemiluminescence and AM chemiluminescence were not significant. These results suggest that ginseng treatment leads to an activation of PMNs and modulation of the IgG response to P. aeruginosa, enhancing the bacterial clearance and thereby reducing the formation of immune complexes, resulting in a milder lung pathology. The changes in IgG1 and IgG2a subclasses indicate a possible shift from a Th-2-like to a Th-1-like response. These findings indicate that the therapeutic effects of ginseng may be related to activation of a Th-1 type of cellular immunity and down-regulation of humoral immunity.

Animals↗
PubMed1998

Serological diagnosis of experimental Enterococcus faecalis endocarditis.

A modified rat model of endocarditis with catheterization for 2 days was established in female Lewis rats using different inocula of Enterococcus faecalis (strain no. EF 19) in order to measure IgG antibodies in serum during the course of infection. Increasing the inocula intravenously resulted in an increase in the CFU/g vegetation and the CFU/g spleen, the ID50 being about 10 CFU/ml and the ID90 about 1x10(2) CFU/ml. The lowest bacterial inoculum infecting 100% of the rats was 3x10(3) CFU/ml, and for further investigations we used this inoculum size. Rats were sacrificed on day 2, 5, 7, 9, 11 and 28 after infection. The CFU/g vegetation and the CFU/g spleen increased until day 7 and then decreased. Serum samples were collected from 129 rats at different times after challenge. Three different ELISA systems were established to measure the IgG antibody responses: E. faecalis sonicate ELISA (a pool of four sonicates of strain no. EF 10, EF 11, EF 19 and EF 48), E. faecalis whole cell ELISA (strain no. EF 19) and E. faecalis purified cell wall ELISA (strain no. EF 19). An IgG antibody response was detected already on day 2, and except for a minor decrease on day 6/7 the antibody response continued to increase until day 14 (whole cell ELISA and sonicate ELISA) and day 21 (purified cell wall ELISA) when a plateau was reached. Significant increases in IgG antibody responses (p<0.05) were found between groups of rats from days 0-2, 2-8/9 and 8/9-14 in the E. faecalis whole cell and sonicate ELISAs and from days 0-2, 2-10/11 and 10/11-21 in the E. faecalis purified cell wall ELISA. In conclusion, we established a model of endocarditis in rats with catheterization for 2 days and were able to demonstrate an increase in IgG antibodies during the course of infection.

Animals↗
PubMed1997

MCA sarcomas induced in scid mice are more immunogenic than MCA sarcomas induced in congenic, immunocompetent mice.

With the aim of studying possible T-cell mediated selection of the cells in growing tumours, 108 mice of the C.B-17 strain, either immunocompetent C.B-17 mice or histocompatible immunodeficient C.B-17 severe combined immune deficiency (scid) were treated with 3-methylcholanthrene (MCA) in two different dosages. A total of 51 tumours were obtained, 44 of which were established as uncloned tumour cell lines, and used for further study. Tumour incidence correlated with carcinogen-dosage in that more tumours developed in groups treated with a high MCA dose than in groups treated with a low MCA dose, but not with immune status of the tumour host. No significant difference in the level of MHC class I molecule expression was found between the two groups of tumours. The rate of rejection after transplantation to syngeneic immunocompetent hosts was significantly higher for the scid tumours than for the non-scid tumours. The authors suggest that this reflects an immunoselection performed by T cells in the immunocompetent host in which the tumour originated, which has eliminated highly immunogenic tumour cells, leaving non-immunogenic tumour cells to grow.

Animals↗
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

Ginseng treatment reduces bacterial load and lung pathology in chronic Pseudomonas aeruginosa pneumonia in rats.

The predominant pathogen in patients with cystic fibrosis (CF) is Pseudomonas aeruginosa, which results in a chronic lung infection associated with progressive pulmonary insufficiency. In a rat model of chronic P. aeruginosa pneumonia mimicking that in patients with CF, we studied whether the inflammation and antibody responses could be changed by treatment with the Chinese herbal medicine ginseng. An aqueous extract of ginseng was injected subcutaneously, and cortisone and saline were used as controls. Two weeks after challenge with P. aeruginosa, the ginseng-treated group showed a significantly improved bacterial clearance from the lungs (P < 0.04), less severe lung pathology (P = 0.05), lower lung abscess incidence (P < 0.01), and fewer mast cell numbers in the lung foci (P < 0.005). Furthermore, lower total immunoglobulin G (IgG) levels (P < 0.01) and higher IgG2a levels (P < 0.025) in serum against P. aeruginosa sonicate and a shift from an acute type to a chronic type of lung inflammation compared to those in the control and cortisone-treated groups were observed. These findings indicate that ginseng treatment of an experimental P. aeruginosa pneumonia in rats promotes a cellular response resembling a TH1-like response. On the basis of these results it is suggested that ginseng may have the potential to be a promising natural medicine, in conjunction with other forms of treatment, for CF patients with chronic P. aeruginosa lung infection.

Animals↗
PubMed1997

Expression of matrix metalloprotease-9 in vascular pericytes in human breast cancer.

Matrix metalloprotease-9 (MMP-9; 92-kd type IV collagenase, gelatinase B) is regarded as important for degradation of the basement membrane and extracellular matrix during cancer invasion and other tissue-remodeling events. Expression of MMP-9 was analyzed in 22 cases of human ductal breast cancer by immunohistochemistry and in 8 of these cases also by in situ hybridization. For immunohistochemistry we used affinity-purified polyclonal antibodies as well as a MMP-9-specific monoclonal antibody (clone 6-6B). Three different stromal cell types with a positive MMP-9 immunoreaction were identified morphologically: neutrophils and macrophage-like cells in all cases and vascular cells in 16 of 22 cases. Double immunofluorescence with antibodies to CD68 conclusively demonstrated MMP-9 expression in macrophages. To identify the positive vascular cells, we employed antibodies to von Willebrand factor and PAL-E for identification of endothelial cells, high molecular weight melanoma-associated antigen for pericytes, and alpha-smooth muscle actin for vascular smooth muscle cells. Using conventional and confocal double immunofluorescence microscopy, colocalization of MMP-9 was seen with high molecular weight melanoma-associated antigen, the pericyte marker, whereas little or no coexpression was seen with alpha-smooth muscle actin. Virtually no coexpression was seen with the endothelial cell markers PAL-E and von Willebrand factor. In situ hybridization showed that MMP-9 mRNA colocalized with MMP-9 immunoreactivity in macrophages and vascular structures, whereas no MMP-9 mRNA was detected in neutrophils. No MMP-9 immunostaining or in situ hybridization signal was detected in cancer cells in any of the cases. Based on these results, it is concluded that MMP-9 in human breast cancer is located in tumor-infiltrating stromal cells, including neutrophils, macrophages, and vascular pericytes, and that the latter two cell types also produce this metalloprotease. We suggest that the MMP-9 produced in pericytes may play a role in extracellular matrix degradation during tumor angiogenesis.

Actins↗
PubMed1997

Chronic Pseudomonas aeruginosa lung infection is more severe in Th2 responding BALB/c mice compared to Th1 responding C3H/HeN mice.

The chronic Pseudomonas aeruginosa lung infection in cystic fibrosis (CF) is characterized by a pronounced antibody response and microcolonies surrounded by numerous polymorphonuclear neutrophils (PMN). Poor prognosis is correlated with a high antibody response to P. aeruginosa antigens. An animal model of this infection was established in two strains of mice: C3H/HeN and BALB/c, generally known as Th1 and Th2 responders, respectively, which were challenged with alginate-embedded P. aeruginosa. Mortality was significantly lower in C3H/HeN compared to BALB/c mice (p < 0.025). P. aeruginosa was cleared more efficiently in C3H/HeN mice and significantly more C3H/HeN mice showed normal lung histopathology (p < 0.02), and we found significantly fewer microabscesses in C3H/HeN mice than in BALB/c mice (p < 0.005). In supernatants from P. aeruginosa antigen and concanavalin A-stimulated spleen cells from the two strains of mice, the interferon-(IFN-) gamma levels were higher, whereas IL-4 levels were lower in C3H/HeN mice than in BALB/c mice. The implications of these findings for CF patients with chronic P. aeruginosa lung infection are discussed.

Animals↗
PubMed1996

Metastasis of mammary carcinomas in GRS/A hybrid mice transgenic for the mts1 gene.

Transgenic mice, carrying the mts1 gene, one of the genes involved in the acquisition of the metastatic phenotype, were generated. The mts1 gene was placed under the control of the mouse mammary tumor virus (MMTV) long terminal repeat (LTR) promoter leading to overexpression in the lactating mammary gland of transgenic animals. Animals bearing the transgene appear phenotypically normal. Animals of two transgenic lines (Tg463 and Tg507) were crossed with the GRS/A mice. The GRS/A strain is characterized by high incidence of mammary tumors which rarely metastasize. 40% of the tumor bearing hybrid GRS/A mts1 females were found to develop secondary tumors in the lungs. The Mts1 protein was detected in the transgene primary tumor cells as well as in the corresponding metastases. Nontransgenic littermates expressed the Mts1 protein only in the stromal cells surrounding the tumor but not in the tumor cells by itself. Taken together these observations indicate that overexpression of the mts1 gene in the mouse mammary carcinoma cells gives rise to more aggressive tumors which are able to metastasize.

Animals↗
PubMed1996

Chemically induced sarcomas from nude mice are more immunogenic than similar sarcomas from congenic normal mice.

To detect possible differences in immunogenicity between tumors induced in T cell-deficient mice and phenotypically normal congenic mice, 16 sarcomas, 8 having developed in nude BALB/c mice and 8 having developed in congenic normal (nu/+) mice, were transplanted to normal BALB/c recipients and the rates of rejection or acceptance were registered. The 16 tumors were chosen randomly from a panel of 39 sarcomas induced with 0.5% or 0.1% 3-methylcholanthrene and maintained as cell lines in culture. Out of the tumors originating from nude mice, 66% were rejected by the normal BALB/c recipients, while only 30% of the tumors originating from normal mice were rejected. Tumors with short induction times from normal mice were more readily accepted than tumors with long induction times. Tumors originating from nude mice had significantly longer mean latency times after transplantation to both normal and nude recipients than tumors originating from normal mice. Contrary to what has been reported by others, there was no correlation between the rejection rates of the individual tumors and their Kd, Dd or Ld major histocompatibility complex (MHC) class I surface expression as measured by flow cytometric analysis of cultured tumor cells. The Kd, Dd and Ld proteins of the transplanted tumor lines were analyzed by isoelectric focusing for the occurrence of mutations resulting in altered charge of the MHC protein. No such mutations were found, ruling out MHC mutations of that kind as the source of immunogenicity in the cell lines used in these experiments. Our results suggest the existence of a T cell-mediated selection in the original tumor cell mass of tumors induced in normal mice, adapting the tumor to growth in a host with a functional T cell system, but apparently there is no connection between this loss of immunogenicity and loss of MHC class I expression.

Animals↗
PubMed1996

Interferon-gamma (IFN-gamma) treatment decreases the inflammatory response in chronic Pseudomonas aeruginosa pneumonia in rats.

In a rat model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis (CF), we studied whether the inflammatory response could be altered by intraperitoneal treatment with recombinant rat interferon-gamma (rrIFN-gamma). Rats were treated either before or after intratracheal challenge with P. aeruginosa embedded in alginate beads. Rats treated after challenge had a significant reduction in the severity of macroscopic lung inflammation compared with rats treated before challenge (P = 0.004) and controls (P = 0.003). The histopathology in controls was dominated by numerous polymorphonuclear leucocytes (PMN) (> or = 90%) surrounding the alginate beads like in CF. This could be caused by a Th2-like response. In contrast, a complete shift to a chronic-type inflammation dominated by mononuclear leucocytes (> or = 90% lymphocytes and plasma cells) and granulomas was observed in both rrIFN-gamma-treated groups of rats. This could be caused by a Th1-like response. There was no significant difference in lethality between the groups, and the antibody titres against P. aeruginosa sonicate and alginate were similar in the treated rats and controls. Since the ongoing lung tissue damage in CF patients has been shown to be caused by elastase secreted by PMN, which dominate the P. aeruginosa lung infection, our findings offer a possible new strategy of modifying the inflammatory response in CF patients.

Animals↗
PubMed1996

Methylcholanthrene-induced sarcomas in nude mice have short induction times and relatively low levels of surface MHC class I expression.

In order to study the role of the T-cell-mediated immune defense in tumor development, a total of 93 sarcomas were induced using different doses (8 micrograms (0.1%), 40 micrograms (0.5%) and 400 micrograms (5%)) of 3-methylcholanthrene in athymic nude Balb/c mice and phenotypically normal immunocompetent Balb/c mice. A shorter tumor induction time and a higher tumor incidence after treatment with low doses of methylcholanthrene were seen in nude mice than in immunocompetent mice, indicating that they have a lower resistance to the carcinogen. Contrary to expectations we found that the MHC class I expression of tumors from nude mice was lower than that of tumors from normal mice. Higher surface expression of MHC class I was demonstrated on high dose tumors from normal mice than on low dose tumors from normal mice. The cellular composition of the individual tumors raised in nude mice was more heterogeneous with respect to MHC class I expression. Since the mice differ genetically only with respect to the nu gene, these results indicate that a lack of T-cell-mediated defense mechanisms may confer upon the bearer a lower resistance to 3-methylcholanthrene and a different MHC profile of the ensuing tumor.

Animals↗
PubMed1996

Cytotoxicity and proliferation of splenocytes and lymph node cells from adjuvant-treated nude mice. Studies of natural and in vitro activation.

The cytotoxicity of NK cells and lymphocytes derived from nonadherent splenocytes (SPL) and regional lymph node cells (LNC) from complete Freund's adjuvant (CFA)-treated athymic nude young (4-6 weeks) and aged (over 1 year) BALB/c nu/nu mice in vitro activated with rIL-2, anti-CD3 mAb or PPD was analyzed and compared to SPL and LNC from age-matched euthymic BALB/c mice. The high natural cytotoxicity to YAC-1 target cells of SPL or LNC could be augmented by 48 h stimulation in vitro with rIL-2, especially when derived from young nude BALB/c mice. The increase in cytotoxic activity was accompanied by increased proliferative activity of both SPL and LNC, which showed statistically significant differences between the rates of stimulation of cells from the young and aged groups. Anti-CD3 mAb strongly activated the cytotoxicity of BALB/c euthymic donor effector cells against P-815 target cells, corresponding to a very high proliferative activity of these cells, but anti-CD3 mAb did not lead to activation of effector cells from nude donors. FACS analyses of antigenic markers similarly showed an increased number of T cells in LNC from aged BALB/c nude donors, which, however, never reached the levels of those of euthymic animals.

Aging↗
PubMed1996

Nerve growth factor receptor expression in heterotransplanted vestibular schwannoma in athymic nude mice.

Nerve growth factor (NGF) has the potential to induce cellular differentiation in various neoplastic and non-neoplastic cell lines. The purpose of the present study was to determine by immunohistochemistry: the presence/distribution of nerve growth factor receptor (NGFr), cellular proliferation expressed by Ki-67, and intratumoral vascularization visualized by the endothelial marker CD 31, in a series of 61 human vestibular schwannoma heterotransplants in athymic nude mice. The immunohistochemical results were correlated to the observed macroscopic growth in 22 heterotransplants (36%) with obvious macroscopic growth, versus 39 heterotransplants (64%), that were stationary or regressed. The positive immunoreactivity to NGFr, number of Ki-67 positive nuclei and number of intratumoral vessels were significantly higher in the 22 (36%) growing heterotransplants than in the 39 heterotransplants (64%), which were stationary or regressed (p < 0.00005, p = 0.046, p < 0.00001). NGFr was statistically related to the vascularity of the heterotransplants expressed by CD 31 (p<0.00001). No significant relation was observed between NGFr and the proliferation, as estimated by Ki-67. The results revealed that the macroscopic growth of VS in athymic nude mice was associated with strong positive expression of NGFr, high cellular proliferation expressed by Ki-67 and vivid neovascularization expressed by CD 31. The possible clinical applicability of the achieved results is discussed.

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