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Biomedical subjects

J Rygaard

Publications and source records attributed to J Rygaard.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1983

Immunological reconstitution of nude mice transplanted with human malignant tumours.

The effects of neonatal murine thymus grafts implanted in nude mice previously transplanted with three different human malignant tumours were studied. Reconstitution resulted in tumour rejection, which started 2-3 weeks after thymus implantation and was complete after 3-6 weeks. The rejection process showed a characteristic histologic picture with 3 phases, an early, an intermediate, and a late phase, which were similar in the 3 tumour types examined. Histological examination of lymphoid tissues of successfully thymus grafted mice showed reconstitution of varying degrees. Numbers of plaque forming cells (PFC) of the spleen of tumour transplanted, thymus grafted mice were equal to or higher than the numbers of PFC in normal BALB/c controls. Mice, thymus grafted only always showed intermediate PFC-values. Responses to the T-cell mitogen, phytohaemagglutinin-P (PHA) were only partially reconstituted, whether the nude mice were tumour transplanted or not. In addition tumour rejection in tumour-bearing nude mice treated with T-cells only, was studied. The rejection process was similar to that observed when a whole thymus gland was implanted. Finally, implantation of embryonic bovine thymus grafts was performed in tumour transplanted nude mice. When these grafts were accepted, tumours were also rejected. Possible mechanisms of reconstitution and the reasons for the varying results are discussed.

Adenocarcinoma↗
PubMed1982

Suppressor cell activity and beta-cell function in insulin-dependent diabetics.

Immunological mechanisms may play a role in the pathogenesis of insulin-dependent diabetes mellitus (IDDM), and suppressor cell activity (SCA) has been found depressed at diagnosis. The aim of the present study was to elucidate whether patients with preserved beta-cell function display a different SCA than other patients. Sixteen patients without and 12 patients with beta-cell function after averagely 9 years' duration of IDDM were examined. The suppressive effect of lymphocytes was investigated after incubation with concanavalin A followed by inactivation. Suppression was measured as the ability of the lymphocytes to inhibit 3H-thymidine incorporation in concanavalin A stimulated normal donor lymphocytes. The main findings were: (1) No significant differences in SCA between patients with and without beta-cell function, and one of these patient groups had SCA significantly different from normal controls. (2) A correlation between SCA and administered dose of insulin among patients without beta-cell function. It is concluded that the actual SCA several years after diagnosis is not connected with the beta-cell function in patients with IDDM.

Adult↗
PubMed1982

Suppressor cell activity in patients with newly diagnosed insulin-dependent diabetes mellitus: a prospective study.

Suppressor cell activity (SCA) was investigated longitudinally, at the time of diagnosis and during the remission period, in 17 patients with insulin-dependent diabetes mellitus (IDDM). The suppressive effect of lymphocytes from patients was investigated after incubation with concanavalin A followed by inactivation. Suppression was measured as the ability of the lymphocytes to inhibit 3H-thymidine incorporation in concanavalin A stimulated normal donor lymphocytes. The main findings were: I. SCA was reduced, on the average, at diagnosis but normal during the remission period. II. Patients with the lowest SCA at diagnosis showed significantly lower C-peptide values during the remission period than other patients. III. No relationship was found between on the one side various tissue types and on the other SCA, C-peptide values, insulin dose, and degree of glucaemic control, neither at diagnosis nor during remission. Previous studies have pointed to the significance of immune reactions in diabetogenesis. The findings in the present study may associate SCA with the development of IDDM.

Adult↗
PubMed1981

Immunological reconstitution of tumour-transplanted and thymus-grafted nude mice.

Two different malignant tumours were transplanted prior to or after thymus grafts in nude mice, and the degree of immunological reconstitution was studied. All mice which rejected either of the tumour types had reconstitution as expressed by an excess of splenic plaque-forming cells. The level of response was dependent upon the age of the thymus graft and whether a tumour was transplanted or not. In contrast, the result of the phytohaemagglutinin stimulation assays of spleen cells were always subnormal in thymus-grafted as well as in thymus- plus tumour-transplanted mice.

Animals↗