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K Buschard

Publications and source records attributed to K Buschard.

At least 91 records · Page 5Linked to original sources
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↗
PubMed1991

The functional state of the beta cells in the pathogenesis of insulin-dependent diabetes mellitus.

Besides the thymus-dependent immune system, growing evidence suggests that the functional state of the beta cell plays a role in the pathogenesis of Type 1 (insulin-dependent) diabetes. Increased incidence of diabetes has been described after increased insulin production and vice versa, and actual hyperinsulinemia has been observed in relation to the diabetogenesis. Prophylactic insulin treatment and intensive insulin therapy at diagnosis are discussed. The studies referred to are mostly animal model investigations of BB rats and NOD mice and-to a lesser degree- of streptozotocin- and encephalomyocarditis-virus-induced diabetes. Also human evidence exists, but naturally of a more sporadic character. Three possible mechanisms behind the beta cell sensitivity as a function of their activity are suggested: increased antigen expression (including both gangliosides and proteins) in beta cells with high activity which could activate the destruction caused by the immune system, and increased susceptibility to the toxicity of interleukins and to diabetogenic agents. With respect to developing preventive treatment the described research area may turn out to be very important. Further studies both in animal models and in humans are awaited.

Animals↗
PubMed1991

Effect of exogenous insulin treatment on fetal growth and maternal alpha-fetoprotein levels in pregnant mice.

The effect of exogenous insulin on the maternal serum level of alpha-fetoprotein and fetal weight was studied. Insulin was given either as one subcutaneous injection on the 13th day of pregnancy (pulse treatment) or as subcutaneous injections each day throughout pregnancy (long-term treatment). Neither of the treatment procedures resulted in a significant alteration in the average fetal weight. However, pulse treatment on the 13th day of pregnancy resulted in elevated maternal serum levels of alpha-fetoprotein and in a greater number of fetuses and larger fetal mass per animal as examined on the 18th day of pregnancy. By contrast, long-term treatment with insulin from the first day of pregnancy resulted in a lower level of maternal serum alpha-fetoprotein and in significantly lower fetal mass per animal. It is concluded that insulin treatment as such, and especially the mode of treatment, plays a crucial role for fetal growth and synthesis of alpha-fetoprotein.

Animals↗
PubMed1990

Prevention of diabetes mellitus in BB rats by neonatal stimulation of beta cells.

Antigen expression in type 1 (insulin-dependent) diabetes may depend on the functional state of beta cells. At birth, beta cells are immature, produce only a basal amount of insulin, and are unresponsive to glucose--but are sensitive to glucagon and arginine. beta cells of spontaneously diabetic BB rats were stimulated for the first 6 days after birth by glucose with glucagon or arginine to accelerate beta cell maturation, and possibly to induce antigen expression and tolerance. Over the first 200 days of life, only 23% of glucose and glucagon-treated BB rats, and 20% of glucose and arginine-treated BB rats developed diabetes, compared with 65% of untreated controls. This finding may explain the observation that children of mothers who have type 1 diabetes are three times less likely to develop the disease than children of fathers with type 1 diabetes. Earlier maturation of beta cells during the diabetic pregnancy may protect against diabetes in later life.

Animals↗
PubMed1990

Type 1 (insulin-dependent) diabetes mellitus diagnosed during pregnancy: a clinical and prognostic study.

The study concerns the clinical outcome and later prognosis (regarding permanent insulin treatment) of patients who develop insulin-dependent diabetes mellitus during pregnancy (which is different from gestational diabetes). Sixty-three such patients (27 +/- 1 (SEM) years old) were delivered at the Copenhagen Centre for Diabetes and Pregnancy during the years 1966-1980. Obstetric complications such as toxaemia were seen in 9.5% of these study patients and the perinatal mortality was 6.3%, both percentages being higher than in the general population (1.1%, p less than 10(-7) and 1.0%, p less than 10(-3), respectively), but similar to those observed in patients with Type 1 diabetes diagnosed before pregnancy. In contrast, the frequency of malformations was 1.6%, the same as in the general population (1.4%), but lower than that seen in patients with long-standing diabetes (8.3%, p less than 0.05). At follow-up examination 8 +/- 1 years after diagnosis all patients were diabetic; 77% were insulin treated, having no or virtually no residual B-cell function, and were clearly Type 1 diabetic patients. After delivery 80% of the patients had a remission period (median 256 days) without insulin treatment. This remission period was absent or shortest in patients with the following characteristics (p less than or equal to 0.03): low age, first parity, not overweight, and high blood glucose level at diagnosis. These prognostic parameters should be considered in obligatory, clinical follow-up plans for such patients.

Adult↗
PubMed1990

Activated CD4+ and CD8+ T-lymphocytes in newly diagnosed type 1 diabetes: a prospective study.

Peripheral lymphocytes from 13 Type 1 diabetic patients (age 28 +/- 11 (+/- SD) years) were studied at diagnosis, and 1 month and 7 months later. The lymphocytes were labelled with phycoerythrin-conjugated anti-HLA-DR antibody and/or fluorescein-conjugated OKT4 or OKT8 antibody, and then studied using a double channel flow-cytometer. The overall percentage of activated T-lymphocytes (CD4+ + CD8+ cells) was (mean +/- SE) 3.1 +/- 0.5% at diagnosis, 2.1 +/- 0.3% at 1 month and 2.2 +/- 0.5% at 7 months test. The percentages at diagnosis and 1 month were higher than in 12 healthy control subjects (1.0 +/- 0.2%, p less than 0.001 and p less than 0.01, respectively). Among the CD4+ cells the percentage of activated cells fell from diagnosis (2.8 +/- 0.7%), to 1 month (1.5 +/- 0.3%, p less than 0.05), and 7 months (1.5 +/- 0.4%, p less than 0.05), whereas among the CD8+ cells they remained unchanged (3.3 +/- 0.6, 2.5 +/- 0.5 and 3.1 +/- 0.6%). The percentage of activated CD4+ cells at diagnosis, and of CD8+ cells at all times, were higher (p less than 0.02) than in control subjects (CD4+, 0.8 +/- 0.2%; CD8+, 1.2 +/- 0.2%). In conclusion, the activated T-lymphocytes present in Type 1 diabetic patients at diagnosis are equally increased among CD4+ and CD8+ cells, but after 7 months the increase is predominantly in CD8+ cells.

Adult↗
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↗
PubMed1990

Interleukin 6: a functional and structural in vitro modulator of beta-cells from islets of Langerhans.

The direct in vitro effect of interleukin-6 (IL-6) on pancreatic beta-cells was studied using isolated Lewis rat islets (25/ml/well) precultured for 7 days and then incubated with or without human recombinant IL-6 (rIL-6) or purified human natural IL-6 (nIL-6). Both sources of IL-6 stimulated insulin secretion over a period of 6 days (P less than 0.01), whereas the levels of insulin within the islets were unaffected. At concentrations above 1.5 ng/ml, rIL-6 almost doubled the content of insulin in the supernatants. At an intermediate concentration, 0.5 ng/ml, rIL-6 preserved insulin secretion by islets cocultured with 2 ng/ml of human recombinant interleukin 1 beta (rIL-1 beta) which otherwise inhibited insulin secretion to 60% of islets cultured in medium alone. Electron microscopic studies showed that rIL-6, 1.5 ng/ml, caused beta-cell specific degenerative changes similar to those previously described after treatment with IL-1 beta; i.e. appearance of opaque intracytoplasmic bodies, autophage vacuoles and signs of mitochondrial degeneration. We conclude that human IL-6 stimulates insulin production and secretion in vitro and induces similar ultrastructural changes in beta-cells as does IL-1 beta. IL-6 may be an endogenous mediator of some of the effects on beta-cells ascribed to IL-1.

Animals↗
PubMed1990

T-lymphocyte subpopulations in pregnant women with newly diagnosed type 1 diabetes.

The thymus-dependent immune system is involved in the disease process underlying Type 1 diabetes. Several studies have thus shown the distribution of peripheral T-lymphocyte subsets to be altered in diabetics. Unlike many other autoimmune diseases which improve during pregnancy, Type 1 diabetes has a higher incidence in pregnant than in non-pregnant women. Therefore, in this study the distribution of lymphocyte subpopulations in the blood was examined in pregnant, newly diagnosed Type 1 diabetic patients and compared with values from non-pregnant patients and healthy controls. The pregnant diabetics displayed a higher percentage of CD8+ cells (28.4 +/- 1.2%) than the non-pregnant diabetics (21.6 +/- 1.3%, p less than 0.005), but did not differ from the controls (29.0 +/- 1.3%). The CD3+ and CD4+ cell distribution displayed no significant difference within the groups. Among the pregnant diabetics a positive correlation was found between the percentage of CD4+ cells and the week of pregnancy when diabetes was diagnosed (p less than 0.01). No other correlations between immunological and clinical parameters were found. Thus the subsets of immune cells are not changed in an autoimmune direction for pregnant, newly diagnosed Type 1 diabetics as they are for non-pregnant. Therefore, the increased incidence of Type 1 diabetes in pregnant women is unlikely to be due to intensified autoimmune alterations in the immune system, but rather to changes induced in the beta-cells during pregnancy as discussed.

Adult↗
PubMed1989

Possible role of IL-1, TNF-alpha, and IL-6 in insulin-dependent diabetes mellitus and autoimmune thyroid disease. Thyroid Cell Group.

Recent experiments indicate a central role of macrophages (M phi), and natural killer (NK) cells, and their products IL-1, IL-6 and TNF alpha in autoimmune endocrine diseases. Intermediate levels of IL-1 alpha/beta inhibit the function of pancreatic beta-cells and thyrocytes, an effect potentiated by TNF alpha. In contrast, low levels of IL-1 potentiate the secretion of insulin and thyroid hormones, and intermediate levels of IL-6 double glucose-induced insulin production by beta-cells. Intermediate and high levels of IL-1 and IL-6 are cytotoxic to normal beta-cells. IL-1 induces IL-6 in isolated islets and in thyrocytes. The cytokines may play a role in the physiological regulation of endocrine functions, for instance during conditions of stress. The genes for TNF alpha and -beta, both located in the MHC region, and IL-6 are polymorphic, and specific alleles may control the amount of cytokine produced. Specific TNF alpha/beta alleles may be in linkage disequilibrium with HLA alleles known to be positively or negatively associated with endocrine and other autoimmune diseases.

Animals↗
PubMed1989

Different percentages of CD8+ lymphocytes in long-term type 1 diabetics with and without residual beta cell function.

About 15% of Type 1 diabetics display residual beta cell function after more than 10 yr duration of diabetes, indicating that the disease mechanisms have stopped before all beta cells are destroyed. Peripheral blood lymphocytes were studied from such patients, 11 females and 12 males, 29 +/- 1 yr old, who had had diabetes for 14 +/- 1 yr. A completely matched group of 23 Type 1 diabetics with the same disease duration, but without residual beta cells, were also studied together with a healthy control group. Lymphocytes were marked with monoclonal OKT antibodies and examined by flow cytometry (FACS). There was no difference between the three groups in the absolute number of lymphocytes and helper T-cells (CD4+:40.2 +/- 1.3 vs. 40.4 +/- 1.3 vs. 41.1 +/- 1.8%). In respect of CD8+ (suppressor/cytotoxic) T-cells, the diabetics without beta cells showed 25.9 +/- 1.0%, significantly less than both the patients with preserved beta cell function (29.0 +/- 0.9%, p less than 0.02) and the controls (29.5 +/- 1.3%, p less than 0.02). CD3+ (pan) T-cells showed parallel changes (67.8 +/- 1.5 vs. 71.0 +/- 1.4 vs. 72.2 +/- 1.4%, p less than 0.05). The metabolic state was similar in the two patient groups, and there was no correlation between metabolic and immunological parameters. It is unknown whether the normalization of the T-cell subpopulation, especially the CD8+ lymphocytes, in patients with residual beta cell function at a point when the disease process is apparently at rest, is of causal significance, or of only marker significance.

Adult↗
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↗
PubMed1988

Metabolic state does not influence lymphocyte subsets in type 1 diabetic patients.

In most studies the distribution of peripheral lymphocyte subsets at diagnosis of type 1 diabetes has been found to be altered. Lymphocyte subpopulations were therefore studied during longitudinal changes in the glycaemic control of 11 type 1 diabetics to investigate whether poor metabolic status affects these results. To avoid any influence of the etiopathogenetic mechanisms, the patients studied had a disease duration of 10 +/- 2 (SEM) years and all but one had no residual beta-cell function. The patients were selected randomly amongst those with a long record of poor glycaemic control and at the first examination they had a mean fasting blood glucose of 15 +/- 1 mmol/l and a mean glucosuria of 67 +/- 11 g/24 h. They were then hospitalized and strictly regulated using pump treatment, resulting in a massive reduction in glucosuria (0 +/- 0 g/24 h) and fasting blood glucose (6 +/- 1 mmol/l) at a second examination a week later. Five of the patients were tested for a third time 35 +/- 4 days later and were still in very good glycaemic control. Peripheral lymphocytes were labelled with monoclonal antibodies and examined by flow cytometry (FACS). Neither CD3+ (pan) T-lymphocytes, CD4+ (helper) T-cells, CD8+ (suppressor/cytotoxic) T-cells, the relation between CD4+ and CD8+ T-cells, nor the total amount of lymphocytes, changed significantly between the first, second, and third examination. None of the results were significantly different from those of healthy controls. There was no correlation between any of the immunological and metabolic parameters. It is concluded that metabolic influence on the distribution of lymphocyte subsets is unlikely.

Adult↗
PubMed1987

Increased incidence of true type I diabetes acquired during pregnancy.

A longitudinal study was carried out of all patients with newly acquired insulin dependent diabetes during pregnancy (as distinct from non-insulin-dependent gestational diabetes) seen at the Copenhagen Centre for Diabetes and Pregnancy during 1966 to 1980. The series comprised 63 patients with a mean age of 27 (SEM 1) years. At diagnosis the mean fasting blood glucose concentration was 15.6 (1.3) mmol/l and mean maximal insulin dose 49 (3) IU/day. At a prospective follow up examination a mean of 8 (SEM 1) years after diagnosis 46 of 60 patients (77%) were being treated with insulin (35 (2) IU/day) and had a very low mean stimulated plasma C peptide value (0.12 (0.02) nmol/l) suggesting absent or nearly absent beta cell function. The remaining 14 patients (23%), not currently receiving insulin, appeared to be severely glucose intolerant, having a mean fasting blood glucose concentration of 13.4 (1.2) mmol/l. Thus most of these patients developing insulin dependent diabetes during pregnancy had true type I disease. Compared with the age specific incidence of type I diabetes in the background population of women the incidence was at least 70% higher in pregnant than non-pregnant women (p less than 0.001; chi 2 = 11.6; f = 1). This increased incidence occurred in the third trimester when the risk of developing type I diabetes was 3.8 times that of non-pregnant women (p less than 0.000001; chi 2 = 35.6; f = 1). Finally, the risk of developing insulin dependent diabetes during pregnancy was lower when conception occurred in the winter (p less than 0.05; chi 2 = 4.18; f = 1).

Adult↗
PubMed1987

HLA associations in insulin-dependent diabetes mellitus diagnosed during pregnancy.

Sixty out of 63 patients with insulin-dependent diabetes mellitus (IDDM) diagnosed during pregnancy in the Diabetes Centre at the Department of Obstetrics and Gynaecology, Rigshospitalet, Copenhagen, were re-examined 2-16 years after diagnosis. Fourty-six patients were currently insulin-treated and the remaining 14 patients were all severely glucose intolerant. HLA-typing was carried out in 41 of these patients. The HLA phenotype distribution showed a highly significant difference from that of non-diabetics but was similar to that seen in IDDM not related to pregnancy. Thus, pregnancy may constitute a special trigger mechanism for IDDM, but the subsequent pathogenic mechanisms are probably the same as those involved in other cases of IDDM.

Diabetes Mellitus, Type 1↗
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

Keratin proteins in human oral mucosa.

We have examined the keratin proteins in normal human oral mucosa from 6 different regions including hard palate, buccal mucosa, tongue, gingiva and floor of the mouth. Urea-dithiothreitol extracts of EDTA separated epithelia were analysed by SDS-PAGE and immunoblotting. Eight samples from each region were investigated and showed very little individual variation in the keratin profile on Coomasie Blue-stained gels. The keratinizing hard palate and gingiva expressed identical patterns and resembled the pattern of epidermis from the flank region. The normally non-keratinizing buccal mucosa and the mucosa of the floor of the mouth expressed polypeptides distinctly different from those of the keratinizing epithelia and lacked the high molecular weight keratins. The dorsal surface of the tongue and the commissure region showed a pattern intermediate between keratinizing and non-keratinizing epithelia. The greater sensitivity of the immunoblotting technique revealed that the non-keratinizing epithelia synthesized one of the high molecular polypeptides and that the tongue produced all the bands found in keratinizing epithelia, but in very small quantities. There are, thus, distinct differences in the keratin expression of oral epithelia which are related to the pattern of keratinization assessed histologically.

Adult↗