PubMed Health⌕ Search

Biomedical subjects

J Rygaard

Publications and source records attributed to J Rygaard.

At least 19 recordsLinked to original sources
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.

Animals↗
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

Gonadotropin-releasing hormone agonist suppression of ovarian tumorigenesis in mice of the Wx/Wv genotype.

Although many investigations have shown a correlation between elevated gonadotropin levels and ovarian tumors (the gonadotropin theory), the ovarian response to a specific suppression of the gonadotropins has not been elucidated. The ovaries of (C57BL/6J x C3H/HeJ)F1-Wx/Wv mice, which contain 1% of the normal oocyte count at birth, rapidly lose the follicular apparatus and develop a 100% incidence of bilateral complex tubular adenomas from the surface germinal epithelium, which is also the origin of 90% of human ovarian carcinomas. Plasma levels of LH and FSH are known to rise fourfold during the period of tumorigenesis. We compared tumor development in Wx/Wv mice after either injecting a GnRH agonist (3.6 mg slow-release goserelin depot, Zoladex Depot) or administering a sham injection every 28 days from the age of 7 days up to 245 days. All 15 Wx/Wv mice that received sham injections developed bilateral ovarian tubular adenomas from the surface germinal epithelium. In none of the 11 mice receiving the GnRH agonist was any tumor found (p < 0.00005), and a significant suppression of the gonadotropins was demonstrated (p < 0.00005).

Adenoma↗
PubMed1995

Localization of NCAM on NCAM-B-expressing cells with inhibited migration in collagen.

The extracellular matrix is a key element in neuronal development and tumour invasion, providing a substratum which sustains the adhesion and migration of cells. In order to study interactions between the neural cell adhesion molecule (NCAM) and collagen, we transfected mouse L cells with cDNA encoding the human transmembrane NCAM isoform of 140 kDa (NCAM-B). An L-cell/collagen type I system was used to study the influence of NCAM expression on in vitro invasion. We here report that migration of NCAM-expressing cells in collagen was inhibited compared to that of NCAM-negative cells transfected with the empty vector. Immunofluorescence confocal laser scanning microscopy (CLSM) and immunogold electron microscopy using anti-human NCAM antibodies demonstrated a heterogeneous distribution of NCAM on the plasma membrane of transfected L cells grown on collagen. NCAM was preferentially located at the surface of broad cytoplasmic protrusions and slender extensions, some of which were facing the collagen. This was in contrast to the homogeneous surface distribution of NCAM on cells grown on plastic. These data suggest that NCAM and collagen type I interact, and that this might lead to the migration inhibition of NCAM-expressing cells.

Animals↗
PubMed1995

Vaccination promotes TH1-like inflammation and survival 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 vaccination. Rats were immunized with either a depolymerized alginate toxin A conjugate (D-ALG toxin A), purified alginate, an O-polysaccharide toxin A conjugate, or sterile saline. After challenge none of the rats immunized with D-ALG toxin A died, in contrast to the other two vaccine groups combined (p = 0.03). A significant reduction in the severity of the macroscopic lung inflammation was seen in rats immunized with D-ALG toxin A, compared with the other three groups (p = 0.009). The histopathologic response in the control rats was dominated by numerous polymorphonuclear leukocytes (PMN) surrounding the alginate beads. In contrast, the histopathologic response in rats immunized with D-ALG toxin A changed within the first week after challenge from predominantly PMNs (TH2-like) to a chronic-type inflammation dominated by mononuclear leukocytes (TH1-like). In accordance, the antibody titers induced by the D-ALG toxin A vaccine were not different from those of the control rats after challenge. This study identifies a possible new way of modifying the inflammation and thereby preventing the PMN-mediated lung tissue damage during chronic P. aeruginosa lung infection in CF.

Alginates↗
PubMed1995

Experimental chronic Pseudomonas aeruginosa lung infection in rats. Non-specific stimulation with LPS reduces lethality as efficiently as specific immunization.

In a rat model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis, we investigated the possibility of preventing chronic lung inflammation or decreasing the progression of the infection. We compared the lethality, pathology, bacterial clearance, and immunogenicity after stimulation of the non-specific defence mechanisms by Escherichia coli lipopolysaccharide (LPS) or P. aeruginosa sonicate, or the acquired specific immune response by vaccination with the same bacterial antigens. One day prior to challenge with P. aeruginosa embedded in alginate beads, rats were stimulated with either E. coli LPS or P. aeruginosa sonicate. Four and two weeks prior to challenge other rats were vaccinated with either E. coli LPS or P. aeruginosa sonicate. Controls did not receive any stimulation or vaccination. The lethality after challenge was lower in rats stimulated with E. coli LPS (p = 0.02) or vaccinated with P. aeruginosa sonicate (p = 0.03) as compared to controls. The histopathology of the surviving rats showed an acute inflammation dominated by polymorphonuclear leukocytes (PMNs), but the offending bacteria were not completely eliminated in any group. The increased survival was probably due to earlier recruitment of PMNs most likely mediated by either cytokines and other chemotactic factors (stimulated group) or the immune response in concert with the complement cascade (vaccinated group). The results of the present and previous vaccination studies show that it is possible to improve survival but not to prevent the chronic P. aeruginosa lung infection and inflammation caused by alginate-embedded bacteria.

Animals↗
PubMed1994

Gene transfer into cultured human epidermis and its transplantation onto immunodeficient mice: an experimental model for somatic gene therapy.

To try epidermis as a target for somatic gene therapy we studied transfected primary human keratinocytes grown in culture and grafted onto athymic mice. We have developed a novel technique for grafting cultured epidermal sheets onto mice. First, the graft is placed on the dorsal muscle fascia underneath the mouse skin using the latter as a bandage. Secondly, the mouse skin above the graft is removed, which exposes the grafted skin to open air and thus stimulates terminal differentiation. A novel method for the discrimination between murine and human epidermal cells is also presented, employing in situ hybridization with human Alu repeated DNA sequences. During monolayer culture the keratinocytes were lipofected with the gene for human growth hormone in an Epstein-Barr virus-based expression vector. The cells were allowed to develop a multilayered tissue for 5 d, secreting human growth hormone into the medium at a daily rate of at least 50 ng/cm2 of tissue. The transfected tissues were then grafted onto mice. We detected human growth hormone at levels of up to 2.6 ng/ml in mouse serum for 4 d, but later no human growth hormone could be found, although the transplants survived for months. To investigate the fate of the transfected cells in the transplanted tissue, we labeled them with the beta-galactosidase reporter gene. The cells staining positive for X-gal were found exclusively in the most superficial differentiated layers at 7 d after transplantation. This may be the main reason why no human growth hormone is found in the mouse circulation at this time.

Animals↗