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J Rygaard

Publications and source records attributed to J Rygaard.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1991

Reduction of diabetes incidence in NOD mice by neonatal glucose treatment.

The aim of this study was to investigate whether neonatal glucose treatment influences the incidence of diabetes in NOD mice. Thirty-nine NOD mice (19 males, 20 females) were treated with 8 g glucose/kg BW/day administered by subcutaneous injections twice a day for the first six days of life. Thirty-six untreated NOD mice (20 males, 16 females) served as a control group. In the glucose-treated group, 33% became diabetic compared with 58% in the control group (X2 = 5.3, p = 0.021). Among the glucose-treated males, 16% became diabetic compared with 50% of the untreated males (X2 = 5.5, p = 0.019), whereas 50% of the glucose-treated females became diabetic compared with 69% of the untreated females (X2 = 1.1, NS). We conclude that neonatal glucose treatment can reduce the diabetes incidence in NOD mice. These results could have implications for the prevention of type 1 diabetes mellitus in humans.

Animals↗
PubMed1991

Pancreatic islet-cell epitope recognized by an anti-sulphatide monoclonal antibody.

Insulin-dependent (Type 1) diabetes mellitus is recognized as an autoimmune disease and islet-cell antibody (ICA) is present in the majority of patients at diagnosis. ICA labels both beta and alpha cells and is believed to be directed against a glycolipid. In this study we examine the presence of sulphatide (3'-sulphogalactosylceramide) or closely related structures (sulpholactosylceramide and seminolipid) in islet cells by means of a monoclonal antibody, Sulph I. Histological examination of pancreatic tissue from Lewis and BB rats, and BALB/c and NOD mice showed a pronounced labelling of the islets of Langerhans with Sulph I. No staining of the exocrine pancreatic tissue, the heart, the liver, the adrenals, the thymus, the spleen or lymph nodes was seen, but staining of some tubular cells and glomerular cells in the kidney as well as of myelin in nerve cells was found. Cytological examination of isolated Lewis islet cells and their cell subpopulations, separated using a fluorescence-activated cell sorter (FACS), showed positive surface labelling of 97.3 +/- 2.2% (SD) of the beta cells and 84.4 +/- 3.0% of the non-beta cells. Thus, the epitope on the glycolipid sulphatide or closely related structures is--with the exception of neural and certain kidney tissue--specifically present in islet cells. Furthermore, the staining pattern of the antibody used, Sulph I, was equivalent to that of ICA.

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↗
PubMed1990

Dependence of antigen expression on functional state of beta-cells.

Antigen expression corresponding to anti-islet cell surface monoclonal antibodies IC2 and A2B5 was studied. IC2 is a rat-rat hybridoma autoantibody produced from the BB rat; among islet cells, IC2 is beta-cell specific. A2B5 is an anti-ganglioside antibody described as labeling beta-cells. Islets of Langerhans from Lewis rats were isolated and cultured for 18 h in RPMI-1640 with five different glucose concentrations (2.2, 3.3, 5.5, 11.1, and 18.3 mM). In some experiments, islets were precultured for 2 or 3 days. After isolation of islet cells and antibody labeling, the percent of IC2+ beta-cells in the different groups increased from 33.3, 34.5, 40.9, and 57.2 to 58.6% (P less than 10(-6). For A2B5, the percent of labeled islet cells increased from 37.4, 41.8, 46.7, and 53.8 to 56.2% (P less than 10(-4). Thus, increasing glucose concentration leading to higher beta-cell activity implies an increase in antigen expression. Neither A2B5 nor IC2 reacts with insulin, as shown by absorption experiments and immune electron microscopy of binding sites. Electron microscopy of IC2-gold-labeled islet cells substantiated the beta-cell specificity of IC2. In conclusion, expression of the corresponding antigens to IC2 and A2B5 depends on the functional state of the beta-cells; because this has been shown to be an important factor in the development of insulin-dependent diabetes, our findings may be of potential pathogenetic interest.

Animals↗
PubMed1988

Antigen expression of the pancreatic beta-cells is dependent on their functional state, as shown by a specific, BB rat monoclonal autoantibody IC2.

Antigen expression is studied corresponding to a monoclonal autoantibody (IC2) derived from a hybridoma of rat myeloma Y3 cells and splenocytes of the diabetic BB rat. The selective reactivity of IC2 with islet cells has earlier been proven. We studied the possible specificity for beta islet cells, and the possible variation in autoantigen expression. Islet cells were isolated by cautious collagenase and dispase treatment. The cells were labelled with IC2 alone or together with anti-insulin immunoglobulin in double-labelling experiments. Extensive series of cells were examined by immunofluorescence microscopy, and some samples also by flow cytometry. In double-labelling examinations we found that only anti-insulin positive cells could bind the IC2 antibody, thus showing beta-cell selectivity. On the other hand, not all anti-insulin positive cells were IC2-positive. Since insulin treatment has been shown to decrease the incidence of diabetes in the BB rat, islet cells were examined after reduced beta-cell strain. Islet cells from Lewis and Wistar Furth rats display 21.4 +/- 1.4% IC2-positive cells, while islet cells from 24-hour fasting animals showed 7.0 +/- 1.4% (p less than 0.0001). Similar results were seen for BALB/c mice (25.0 +/- 1.8% vs. 13.7 +/- 2.3%, p less than 0.002). Also, after a week of insulin treatment, autoantigen expression was significantly decreased. Thus, the IC2 antibody is beta-cell-specific, and expression of the corresponding cell surface antigen depends on the functional state of the beta-cells.

Animals↗
PubMed1987

Effects of irradiation with dental light curing units on Langerhans cells in human stratified epithelium in heterotransplanted skin.

Grafts of human skin on nude mice were subjected to a single dose of either 2 1/2 min or 4 min of radiation from two different commercial dental light curing units with emission mainly in the visible light spectrum but also with a small fraction of UV-A light. Seventy-two hours after exposure the tissue was examined for presence of Langerhans cells using monoclonal antibody OKT6 double layer immunofluorescence staining. Epithelial hyperplasia and reduced reactivities for OKT6 were seen after 2 1/2 min exposure. After 4 min of exposure OKT6 positive cells were completely absent from the epithelium. The results indicate that emission from dental light curing units can affect Langerhans cells in human epithelium and could thus modify the local immunologic response.

Animals↗
PubMed1987

Effects of xenogeneic, allogeneic and isogeneic thymus grafts on lymphocyte populations in peripheral lymphoid organs of the nude rat.

In order to gain information about the effect of xenografted, allografted and isografted thymic tissue on peripheral lymphoid organs of immune-deficient rats, athymic nude LEW rats of ninth backcross-intercross were grafted with fetal calf and neonatal BDIX and LEW thymus. Adrenalectomy was also performed in some animals in order to obtain a possible enhancement of the immunological reconstitution. Both groups of isogeneic-thymus-grafted animals had more T helper cells than the nude controls. Furthermore, they had more densely populated paracortical areas in the inguinal lymph nodes and higher lymphocyte counts in the thoracic duct lymph. Finally, the inguinal lymph nodes contained germinal centres. Xenogeneic and allogeneic thymus transplants did not induce constant changes in the parameters observed compared with the untreated nudes. No clear difference was observed between the adrenalectomized and non-adrenalectomized thymic-isografted animals. We therefore conclude that of all the experimental animals examined the isografted nude rats show by far the best response and that adrenalectomy seems unnecessary for the success of neonatal isogeneic thymus grafts. We also conclude that the isogeneic-thymus-grafted nude rat is a suitable tool for immunological reconstitution studies.

Adrenalectomy↗
PubMed1987

Prodromal immune manifestations in EMC-M virus induced diabetes: islet bound and circulating antibodies, and changes in lymphocyte subsets.

The thymus-dependence of the encephalomyocarditis (EMC-M) virus induced diabetes has been demonstrated in comparative studies of normal and immunodeficient mice. Since the lymphocytic infiltration in the islets of Langerhans is modest during the virus infection, we have looked for possible indications of humoral immune mechanisms. Using fluorescence microscopy the presence of immunoglobulins in the islets could be shown 3 days after EMC-M-virus inoculation, gradually disappearing about day 14. The Ig deposit is scattered throughout the islets, but the precise target of Ig's has not been detected. Circulating islet cell surface reactive antibodies were demonstrable from the fourth day until about the third week. This period coincides largely with the period in which Ig deposits were present. Virus antibodies in peripheral blood could not be detected until the fifth day after the virus inoculation, whereas virus could be isolated from the third day. Beginning from day 5, about one third of the mice developed severe hyperglycaemia with blood glucose levels up to 35 mmol/l. Lymphocyte subsets of spleen cells were measured using a fluorescence activated cell sorter. Six days after virus inoculation the mean percentage of Lyt 2-positive (suppressor/cytotoxic) cells decreased below the value for control mice (p less than 0.05), but increased significantly (p less than 0.02) 2 weeks later.

Animals↗
PubMed1986

Human pleomorphic adenomas transplanted to nude mice.

Tissue from 13 human pleomorphic adenomas was transplanted to a total of 64 nude mice. Eight of the tumors were transplanted into a second passage of mice, 17 in all. In 39 mice of first passage, there was a definite increase in graft size. Microscopic examination showed no change in the histologic pattern from the donor tumor to the transplanted tissue. The heterochromatin pattern after staining with the DNA-specific fluorochrome D287/170 allowed distinction between human and murine cells and showed that both epithelial and mesenchymal cells were of human derivation. Autoradiographic studies with tritiated thymidine showed that both epithelial and mesenchymal tumor cells were labeled. Our results thus show that cell proliferation in the human pleomorphic adenoma takes place in epithelial areas as well as in mesenchymal areas.

Adenoma, Pleomorphic↗
PubMed1986

Heterotransplantation of human pleomorphic adenomas to nude mice.

The purpose of the present study was to establish a model for in vivo studies of human pleomorphic adenomas by heterotransplantation of tumour tissue to nude mice. Tissue from 7 tumours was transplanted to a total of 34 mice. Take with obvious growth occurred in 12 mice, and survival of the tissue was seen in an additional 8 mice. The overall histological picture was unchanged from the donor tumours to the transplanted tissue. The possibilities of the model are discussed.

Adenoma, Pleomorphic↗
PubMed1983

Virus-induced diabetes mellitus in mice and the thymus-dependent immune system.

The present study concerns the effect of the experimental diabetogenic encephalomyocarditis (EMC) virus on normal and athymic nude mice of BALB/c origin. The effect of simultaneous immunosuppressive pharmacological treatment with a derivative of cyclophosphamide in a relatively low dose (3 mg/mouse) was also studied. After inoculation with EMC virus, 36% of the normal mice, but none of the nude mice, developed diabetes mellitus and 93% of the normal mice, but none of the nude mice, developed paresis of one or more leg(s). When lower doses of EMC virus were given, few or none of the normal mice developed diabetes or paresis. After treatment with a cyclophosphamide-derivative, the number of paralysed mice increased. EMC virus in abundant amounts could be isolated from the pancreas and heart of all virus-inoculated mice, including the non-diabetic nude mice. Antibodies against EMC virus were found in all groups of virus-inoculated mice, although only in small amounts in nude and immunosuppressed normal mice. Histological examination revealed no significant differences between the islets of Langerhans of the experimental mice, diabetic as well as non-diabetic, and the control mice with respect to lymphocytic infiltration. It is concluded that the thymus-dependent immune system seems to be of decisive importance for the development of diabetes in this virus model.

Animals↗
PubMed1983

T lymphocyte subsets in patients with newly diagnosed type 1 (insulin-dependent) diabetes: a prospective study.

T lymphocyte subsets in peripheral blood from 11 newly diagnosed Type 1 (insulin-dependent) diabetic patients were studied prospectively at three time intervals: as soon as possible after diagnosis, 3 weeks and 5 months later. Lymphocytes were marked with monoclonal OKT antibodies and examined in a fluorescence-activated cell sorter. The percentage of T lymphocytes (OKT3) did not change significantly at the three study times. The percentage of helper/inducer T cells (OKT4) was high the first week after diagnosis, but decreased at the 5-month examination (p less than 0.05). The percentage of suppressor/cytotoxic T cells (OKT8) was low at diagnosis but increased at 3 weeks (p less than 0.02) and 5 months (p less than 0.01). The ratio OKT4/OKT8 lymphocytes was 2.28 at diagnosis, decreasing to 1.77 at 3 weeks and 1.87 at 5 months, compared with 1.46 for 16 age-matched control subjects. There was no significant change in the absolute number of lymphocytes. It is concluded that the distribution of T cell subsets was abnormal at the time of diagnosis, but changed towards normal within a few weeks, after which there was no significant change at 5 months. It is as yet unknown whether the high proportion of helper/inducer T cells and/or the low percentage of suppressor/cytotoxic T cells at diagnosis favour immune reactions involved in the pathogenesis of Type 1 diabetes.

Adolescent↗
PubMed1983

Alterations of peripheral T-lymphocyte subpopulations in patients with insulin-dependent (type 1) diabetes mellitus.

Subpopulations of peripheral T-lymphocytes were studied in two groups of patients with insulin-dependent diabetes mellitus (IDDM): eleven newly diagnosed diabetics and twenty-one patients having diabetes of long duration (13 +/- 1 yr). Monoclonal antibodies to the surface antigens of helper (OKT 4) and suppressor (OKT 8) T-cell subsets and to a common T-cell antigen (OKT 3) were used. The percentage of suppressor T-lymphocytes were found reduced in both the newly diagnosed patients (p less than 0.001) and the patients with long-term IDDM (p less than 0.05) in comparison with 16 age-matched healthy control persons. Furthermore, the newly diagnosed diabetics showed a lower percentage of suppressor T-cells (p less than 0.05) and a higher amount of helper T-cells (p less than 0.01) than the patients with long-term diabetes. Concerning the percentage of the total number of T-cells and the absolute number of lymphocytes, there were no significant differences between the patient groups and the controls. As earlier studies have pointed to the significance of immune reactions in diabetogenesis, a pathogenetic importance of the observed imbalance of subpopulations of T-lymphocytes in IDDM should be considered.

Adult↗
PubMed1983

Plasma from insulin-dependent diabetics inhibits theophylline sensitive T-lymphocytes demonstrated in E-rosette assay.

This study concerns the effect of plasma from patients with insulin-dependent (type 1) diabetes mellitus (IDDM) on the capacity of normal donor lymphocytes to form rosettes with sheep erythrocytes. Parallel incubations were made of normal allogeneic peripheral lymphocytes with plasma from patients with IDDM and from normal donors. Lymphocytes incubated with plasma from 16 patients with newly diagnosed IDDM displayed a mean rosette formation percentage of 48 +/- 2, but 54 +/- 1 when incubated with control plasma (p less than 0.01). Repeated study in the same patients in the remission period gave similar findings; 46 +/- 2 and 53 +/- 2 (p less than 0.01) respectively. After fractionation of the donor lymphocytes, the reduced rosette formation percentage, after incubation with plasma from the diabetics, was found to be within the theophylline sensitive fraction of the lymphocytes, while the rosette formation percentage in the theophylline resistant fraction was normal. The reduction in rosette formation capacity at the time of diagnosis seemed to be independent of the tissue type of the patient. No relationships were apparent between rosette formation percentages and C-peptide, blood glucose values or glucosuria, neither at time of diagnosis nor in the remission period. The glycaemic control was found to be of no significance in rosette formation percentages in a triple study of 7 patients; first badly controlled, then very well controlled, and, finally again poorly controlled, though without severe ketoacidosis. The theophylline sensitive fraction of T-lymphocytes has been assumed to include suppressor T-cells. It is not known at present whether the described inhibition of these lymphocytes is of any pathogenetic significance.

Adult↗