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Biomedical subjects

A Lernmark

Publications and source records attributed to A Lernmark.

At least 289 records · Page 16Linked to original sources
PubMed1982

The low dose streptozotocin murine model of type 1 (insulin-dependent) diabetes mellitus: studies in vivo and in vitro of the modulating effect of sex hormones.

The influence of sex on pancreatic islet B cell susceptibility to streptozotocin was studied in mice given multiple low doses of streptozotocin. Male C3 D2 F1 mice developed a steadily increasing blood glucose level after a lag period of about 3 weeks, in contrast to females who were resistant. Spleen cells from streptozotocin treated female animals produced hyperglycaemia in total body irradiated syngeneic female recipients, but only if the recipients were treated with testosterone. Testosterone treatment of donors did not affect blood glucose levels of recipients. Streptozotocin cytotoxicity in vitro determined by a 51Cr-release assay revealed an increased sensitivity to streptozotocin in dispersed islet cells from adult male animals as compared with cells from adult female mice. The incubation of islet cells from animals of either sex with testosterone, or oestradiol plus progesterone, did not enhance the susceptibility to streptozotocin. Islet cells from sexually immature male or female mice were less susceptible to streptozotocin. The results demonstrate that sex determines susceptibility to streptozotocin in vivo and in vitro.

Animals↗
PubMed1982

Absence of H-2 genetic influence on streptozotocin-induced diabetes in mice.

Five daily injections of streptozotocin (40 mg/kg) produced a delayed but progressively increasing level of hyperglycaemia in long term studies with male Naval Medical Research Institute mice and C3D2F1 (DBA 2 J male x C3H/Tif female) F1 hybrid mice. The development of hyperglycaemia was paralleled by decreased amounts of pancreatic immunoreactive insulin as well as degranulation and necrosis of pancreatic B cells. Insulitis was found from days 9-25 after the first injection of streptozotocin. Compared with the F1 hybrid strain the parental inbred strains DBA 2 J and C3H/Tif demonstrated a certain resistance to streptozotocin. Development of hyperglycaemia did not differ in four congenic resistant lines of mice on the C57 BL/10 genetic background, indicating the major histocompatibility complex genes are not likely to determine susceptibility to streptozotocin-induced islet B cell damage.

Animals↗
PubMed1982

Specific pancreatic beta-cell surface antigens recognized by a xenogenic antiserum.

An antiserum (R4) from a rabbit immunized with suspensions of C57BL/61 ob/ob mouse islet cells contains antibodies which in a 125I-protein A radioligand assay can be demonstrated to bind to single cell suspensions of normal Naval Medical Research Institute (NMRI) mouse islet cells. The binding of 125I-protein A to islet cells was about four times that of normal rabbit serum (NRS) after incubation at a 1/600 dilution of R4 antiserum quantitatively absorbed to mouse spleen lymphocytes (R4A antiserum) and hepatocytes. Subsequent absorption of the R4A antiserum to islet cells significantly reduced the binding of 125I-protein A to islet cells incubated with the doubly absorbed serum. Immunoprecipitation of radiolabeled islet cell lysates followed by SDS polyacrylamide gel electrophoresis and autoradiography suggested that the R4A antiserum recognized a Mr 40,000 glycoprotein. This glycoprotein was not detected in spleen lymphocytes. Electron microscope detection of gold-protein A complexes suggested that the binding of islet cell surface antibodies was cell specific. islet cell suspensions incubated with R4A antiserum and gold-protein A showed that 86 +/- 3 gold particles were bound per 100 beta-cells (mean +/- SE for six experiments). In contrast, the number of gold particles per 100 endocrine non-beta-cells was 8 +/- 1 which was similar to the number achieved with NRS (3 +/- 1) on all endocrine islet cells. Our observations suggest that the pancreatic islet cells, in particular the beta-cells, express a specific antigen.

Animals↗
PubMed1982

Islet transplantation in mice differing in the I and S subregions of the H-2 complex. Effects of presensitization with skin allografts.

Pancreatic islets from A.TH mice were transplanted into the spleen of streptozotocin (SZ)-diabetic A.TL mice. The two strains of mice are congenic inbred strains, differing only in the I and S subregions of the H-2 complex. The allogeneic islet grafts decreased blood glucose temporarily, but the islets were rejected after 21 +/- 7 days (mean +/- SD). The effect of skin presensitization was tested by giving both allogeneic and syngeneic skin grafts to each of a second set of A.TL mice before streptozotocin treatment and islet transplantation. The time course of rejection of the allogeneic islets in animals that received initial skin grafts was decreased to 8 +/- 3 days. In both skin-presensitized and non-presensitized mice syngeneic islet grafts were able to restore normoglycaemia, even in animals that had previously rejected an islet allograft. These observations demonstrate that transplantation of pancreatic islet allografts across the I and S subregions of the H-2 complex is sufficient to induce rejection of the islets. The islet rejection was markedly accelerated by prior sensitization with allogeneic skin grafting. It is suggested that elements in allogeneic skin grafts serve as inducers of cytotoxic T-cell responses directed against gene products of the I and/or S subregions present on cells in the allogeneic islets.

Animals↗
PubMed1982

Metabolic and underlying causes of diabetes mellitus.

It is emphasized that animal models should be used to study specific genotypic or phenotypic expressions associated with diabetes rather than assuming a single animal model can reflect diverse forms of the human disease. Diabetic and normal animals are reviewed on the basis of their usefulness as models of genetic, viral, and chemically induced diabetes, including the often associated immune phenomena. Characteristics of spontaneously diabetic animals with and without obesity are also described with an emphasis on both genetics and metabolic derangements. Recommendations for future animal experimentation include: more longitudinal studies evaluating the role of sex, prenatal environment, diet, and viral or chemical attack on B-cell function; characterization of the immune phenomena associated with B-cell lesions (and insulitis) in diabetic and immunologically incompetent lines; clarification of relationships between obesity and islet-cell function with emphasis on the role of fuel metabolism, vitamins, and minerals; and, finally, the development of new models with specific genetic aberrations placed in normal or diabetic lines.

Alloxan↗
PubMed1982

Islet cell surface antibodies and lymphocyte antibodies in the spontaneously diabetic BB Wistar rat.

Plasma from 14 diabetic and 6 nondiabetic BB Wistar rats along with plasma from 6 non-BB Wistar rats was evaluated for the presence of islet cells surface antibodies (ICSA) and antibodies to spleen lymphocytes by the protein-A radioligand assay. Dispersed Wistar rat islet cells incubated with plasma from diabetic rats bound 4255 +/- 2208 cpm 125I-protein A/5 x 10(4) islet cells (mean +/- SD) compared with 984 +/- 454 cpm/5 x 10(4) islet cells in islet cells incubated with plasma from nondiabetic BB rats (P less than 0.005). Twelve of the 14 diabetic rats with a duration of diabetes for 3-11 days bound radioactivity above the mean and 2 x SC of controls. The binding of 125I-protein A did not differ between nondiabetic BB rats and non-BB Wistar rats. Wistar rat spleen lymphocytes incubated in diabetic plasma bound 20,249 +/- 10,783 cpm/2 x 10(6) spleen lymphocytes compared with 3460 +/- 1809 in the controls (P less than 0.005). Animals positive for ICSA correlated with those positive for spleen lymphocyte antibodies. It is concluded that ICSA and splenic lymphocyte antibodies are present in diabetic BB rats.

Animals↗
PubMed1982

Sorting of pancreatic islet cell subpopulations by light scattering using a fluorescence-activated cell sorter.

Methods have been developed for the preparation of suspensions of viable rat pancreatic islet cells and their analysis and sorting in the fluorescence-activated cell sorter (FACS III or IV). Histograms of cell number versus light scattering in a near forward angle (1-15 degrees) demonstrated that viable islet cells produce a broad peak that is distinctly separated from the peaks generated by exocrine cells, erythrocytes, and nonviable cells. Electron microscopic examination and radioimmunoassay of hormone content in fractions collected across the peak showed that glucagon-containing (A) cells scatter less intensely and are concentrated within the left side of the islet cell peak, while somatostatin-containing (D) cells are localized to the far right side, indicating a higher intrinsic light scattering property of the D-cells. The more abundant insulin-containing (B) cells define the center of the islet cell peak. Sodium dodecyl sulfate slab gel electrophoresis and radioautography of 35S-methionine labeled cellular proteins confirmed that sorted cells are viable. Cells from the far left region contained increased amounts of labeled 18 Kd proglucagon and its 13-Kd and 10-Kd conversion intermediates, while cells from the right side were relatively enriched in labeled 12.4 Kd prosomatostatin. These results demonstrate that intrinsic light scattering alone can be used to prepare A- or D-cell enriched fractions from islets for biochemical analysis.

Animals↗
PubMed1982

Islet cell surface antibodies in spontaneously diabetic BB rats.

Antibodies to normal Wistar rat islet cells are often found in newly diagnosed diabetic BB rats. It was tested if antibodies in BB rats bind to cells from a cloned insulin-producing, rat-insulinoma cell line, RIN 5F, using a protein A-radioligand assay for islet cell surface antibodies. A close correlation was found between the binding of antibodies to islet cells and to RIN 5F cells. Islet cell surface antibodies reactive with RIN 5 F cells were determined in two litters of BB rats, born by diabetic, islet cell surface antibody positive parents. A high incidence (85%) of diabetes was found among 13 offsprings, the mean age of onset being 88 days. At 44 days of age before diabetes was diagnosed, 95% of 20 offsprings were islet cell surface antibody positive. There was no difference in antibody-levels between diabetic and non-diabetic rats. It is concluded that BB rats have circulating antibodies reactive with surface determinants on the RIN-5F insulin-producing cell line. There was a high prevalence of islet cell surface antibodies among young, yet unaffected BB rats.

Animals↗
PubMed1982

Rodent islet cell antigens recognized by antibodies in sera from diabetic patients.

Rat islets, rat insulinoma cells and islets from three different mouse strains were labelled with 35S-cysteine and/or 35S-methionine. Detergent lysates of the cells were subjected to immunoprecipitation with sera from 5 newly diagnosed diabetic children and 5 control sera. The immunoprecipitates were analysed by sodium dodecyl sulphate (SDS)-polyacrylamide gel electrophoresis followed by autoradiography. One of the sera immunoprecipitated a protein of Mr 64K from lysates of rat islets, rat insulinoma cells, A. TH and NMRI but not CBA/H mouse islets. This protein was not consistently immunoprecipitated by the other diabetic sera, however, it was never found with control sera nor was it detected in rodent lymphocytes. Some proteins of lower molecular weight (59K, 57K, 40K, 29K) were specifically immunoprecipitated by one or more diabetic sera from some of the rodent islet cell preparations. It is concluded that rodent islet cells contain a protein of Mr 64K which may be antigenically related to a 64K protein previously detected in immunoprecipitates of human islet cells with the same diabetic sera. The variable results with rat and mouse islet cell material suggest that the level of cross-reactivity is low. Further studies are needed to clarify whether the lower molecular components detected in some immunoprecipitates represent other antigenic determinants or degradation products of the 64K protein.

Adolescent↗
PubMed1982

Insulin release from mouse islets perifused with serum IgG from newly insulin-dependent diabetics.

In the present study we have investigated the effect of IgG isolated from sera of newly diagnosed insulin-dependent diabetic patients (IDD-IgG) on insulin release of column-perifused isolated mice islets of Langerhans in the presence and absence of guinea pig complement. The insulin release is highly significantly (p less than 0.01) increased by IDD-IgG as compared with normal serum IgG in the presence of untreated as well as heat-inactivated GPNS. However, complement exposure suppressed insulin release significantly (p less than 0.01) in each period of perifusion. After perifusion in the presence of complement the arginine-stimulated insulin secretion was 6 times lower than without complement exposure of perifused islets before.

Animals↗
PubMed1982

Isolation of rat major histocompatibility genes expressed in pancreatic beta-cells.

The probable role of cell surface antigens in the development of juvenile diabetes necessitates a detailed study of the proteins expressed on the surface of pancreatic beta-cells. A gene library composed of genes expressed in beta-cells was constructed to provide a source of low abundance genes from those cells. Initial studies with this library have led to the isolation of three genes which share nucleotide and amino acid sequence homology with mouse and human class I major histocompatibility antigens.

Animals↗
PubMed1981

A prospective analysis of antibodies reacting with pancreatic islet cells in insulin-dependent diabetic children.

Islet cell cytoplasmic and cell surface antibodies along with other autogenic tissue antibodies were determined prospectively from the day of diagnosis of insulin-dependent diabetes in a group of children and adolescents. Prior to the initiation of insulin therapy 30 out of 33 were antibody-positive, 67% having islet cytoplasmic antibodies and 67% islet cell surface antibodies. Among 74 age- and sex-matched non-diabetic individuals 1% had islet cell cytoplasmic antibodies and 3% had islet cell surface antibodies. A prospective analysis in 17 patients showed a diminishing prevalence of islet cell antibodies with increasing duration of diabetes. Islet cell cytoplasmic or cell surface antibodies were found independently of each other or in combination and with various patterns of persistence. The results indicate a strong association of islet cell antibodies with the onset of insulin-dependent diabetes in childhood and adolescence.

Adolescent↗
PubMed1981

Autoimmunity in insulin-dependent diabetes mellitus.

Genetic susceptibility, environmental factors and immune mechanisms are implicated in the pathogenesis and etiology of insulin-dependent diabetes mellitus. The onset of the disease is associated with a major loss of beta cells, and inflammatory cells may be seen in and around the islets of Langerhans. Insulin-dependent diabetes is often associated with autoimmune endocrinopathies. Antipancreatic cell-mediated autoimmunity is found predominantly in young patients with insulin-dependent diabetes of recent onset as are antibodies reactive with cytoplasmic components or cell surface determinants of islet cells. Antibodies reactive with live islet cells may mediate complement-dependent cytotoxicity. The antigen(s) in the islet cells remain(s) to be identified and characterized. Further studies will be necessary to determine whether autoimmunity is the cause of beta-cell destruction or whether it is a consequence of damages caused by exogenous agents in susceptible persons.

Animals↗