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Biomedical subjects

A Imagawa

Publications and source records attributed to A Imagawa.

At least 37 records · Page 2Linked to original sources
PubMed1999

Immunological abnormalities in islets at diagnosis paralleled further deterioration of glycaemic control in patients with recent-onset Type I (insulin-dependent) diabetes mellitus.

AIMS/HYPOTHESIS: To determine whether the clinical heterogeneity observed in the development of Type I (insulin-dependent) diabetes mellitus correlates with immunohistochemical differences observed at diagnosis. METHODS: Patients (n = 17) with recent-onset diabetes clinically considered to be insulin dependent (Type I), underwent pancreatic biopsy for immunohistological analysis. These patients were divided into two groups based on the presence or absence of islet immunological abnormalities (insulitis or hyperexpression of MHC class I antigens or both). The patients were also HLA typed and tested for islet cell antibodies and antibodies to glutamic acid decarboxylase (GAD-Ab). All patients were followed monthly for 2 years and their fasting plasma glucose, haemoglobin A1c and daily insulin doses were recorded. The clinical course of patients with islet immunological abnormalities was compared with that of patients without those abnormalities. RESULTS: Patients with and without islet immunological abnormalities did not differ with regard to HLA type or islet cell antibodies. Antibodies to glutamic acid decarboxylase correlated with the presence of insulitis and MHC class I hyperexpression. These local immunological abnormalities were also associated with higher haemoglobin A1c values (p < 0.05) and a trend towards greater insulin requirements. Further, patients with the islet abnormalities had higher fasting plasma glucose concentrations 2 years after the biopsy than at the time of the biopsy (p < 0.05). CONCLUSION/INTERPRETATION: The heterogeneous clinical course observed following diagnosis in patients with Type I diabetes correlates with islet immunological abnormalities. Insulitis and hyperexpression of MHC class I correlate with deteriorating glycaemic control.

Adolescent↗
PubMed1999

Three new mutations in the hepatocyte nuclear factor-1alpha gene in Japanese subjects with diabetes mellitus: clinical features and functional characterization.

AIMS/HYPOTHESIS: Mutations in the hepatocyte nuclear factor-1alpha gene are a common cause of the type 3 form of maturity-onset diabetes of the young. We examined the clinical features and molecular basis of hepatocyte nuclear factor-1alpha (HNF-1alpha) diabetes. METHODS: Thirty-seven Japanese subjects with early onset Type II (non-insulin-dependent) diabetes mellitus and 45 with Type I (insulin-dependent) diabetes mellitus were screened for mutations in this gene. Functional properties of mutant HNF-1alpha were also investigated. RESULTS: Three new mutations [G415R, R272C and A site of the promoter (+ 102G-to-C)] were found. Insulin secretion was impaired in the three subjects. Insulin and glucagon secretory responses to arginine in the subject with the R272C mutation were also diminished. Molecular biological studies indicated that the G415R mutation generated a protein with about 50% of the activity of wild-type HNF-1alpha. The R272C mutation had no transactivating or DNA binding activity and acted in a dominant negative manner. The + 102 G-to-C mutation in the A site of the promoter activity was associated with an increase in promoter activity and it had 42-75% more activity than the wild-type sequence. CONCLUSION/INTERPRETATION: Mutations in the HNF-1alpha gene may affect the normal islet function by different molecular mechanisms.

Adult↗
PubMed1999

Fas and Fas ligand expression in inflamed islets in pancreas sections of patients with recent-onset Type I diabetes mellitus.

AIMS/HYPOTHESIS: Type I (insulin-dependent) diabetes results mainly from T-cell-mediated autoimmune destruction of pancreatic beta cells. Cytotoxic T lymphocytes destroy target cells via a perforin-based or Fas-based mechanism. Our previous study indicated that the Fas-Fas ligand (FasL) pathway is required for the development of autoimmune diabetes in the NOD mouse. We now investigated whether or not the Fas-FasL system is involved in the beta-cell destruction in human Type I diabetes. METHODS: We immunohistochemically analysed pancreas biopsy specimens of 13 recent-onset patients. RESULTS: Pancreatic islets were identified but showed various degrees of reduction in beta-cell volume in all patients. Out of 13 patients 6 had insulitis. In these 6 patients Fas was expressed in both the islets and infiltrating cells but not in either cell type in the 7 other patients without insulitis. Double immunostaining showed that Fas was positive in 92.2 to 97.7 % of beta cells but only in 17.6 to 46.7 % of alpha cells in Fas-positive, insulin-remaining islets. We found FasL was expressed exclusively in islet-infiltrating cells in patients with insulitis. Double immunostaining revealed that the most prevalent phenotype of FasL-positive cells was CD8, which was followed by macrophages and CD4. CONCLUSION/INTERPRETATION: The interaction between Fas on beta cells and FasL on infiltrating cells might trigger selective apoptotic beta-cell death in inflamed islets, leading to immune-mediated Type I diabetes. [Diabetologia (1999) 42: 1332-1340]

Adolescent↗
PubMed1999

In vivo effects of calcium entry blockers on human parathyroid adenoma cells with special reference to calcium sensing ability and the hormone secretion.

We evaluated the effects of calcium-entry blockers on parathyroid hormone (PTH) secretion by human parathyroid adenoma cells in vitro. Nifedipine and bamidipine inhibited PTH secretion, while diltiazem had no significant effect. Cytosolic calcium concentrations were measured by use of the calcium-sensitive fluorescent dye fluo-3 with confocal laser scanning microscopy. Nifedipine increased the cytosolic concentration of calcium, whereas diltiazem decreased it. Results suggest that, in parathyroid adenoma cells, regulation of PTH secretion with respect to intracellular calcium concentration would be maintained despite differing response of intracellular calcium concentration following exposure to calcium-entry blockers.

Adenoma↗
PubMed1998

Molecular mechanisms of pancreatic beta-cell destruction in autoimmune diabetes: potential targets for preventive therapy.

Mononuclear cell infiltration into the islets of the pancreas (insulitis) is characteristic of autoimmune diabetes. T lymphocytes are the predominant subpopulation seen in insulitis, and are involved in the autoimmune process. Insulin-producing beta cells are thought to be destroyed by cytotoxic T cells, cytokines or nitric oxide, and beta-cell death occurs, at least partly, via apoptosis. Beta-cell death induced by cytokines is inhibited by Bcl-2, suggesting its potential as a tool for gene therapy. The Fas/Fas-ligand system plays a critical role in inducing insulitis and overt diabetes in nonobese diabetic (NOD) mice, a model of autoimmune diabetes. T-cell receptor gene usage in infiltrating T cells is not restricted in NOD mice, but there are some observations indicating relative restriction in human IDDM patients. Preventive strategies might be developed by focusing on these molecules involved in beta-cell destruction. The establishment of screening techniques for detecting prediabetic patients is also necessary to allow successful intervention.

Animals↗
PubMed1997

Requirement of Fas for the development of autoimmune diabetes in nonobese diabetic mice.

Insulin-dependent diabetes mellitus (IDDM) is assumed to be a T cell-mediated autoimmune disease. To investigate the role of Fas-mediated cytotoxicity in pancreatic beta cell destruction, we established nonobese diabetic (NOD)-lymphoproliferation (lpr)/lpr mice lacking Fas. Out of three genotypes, female NOD-+/+ and NOD-+/lpr developed spontaneous diabetes by the age of 10 mo with the incidence of 68 and 62%, respectively. In contrast, NOD-lpr/lpr did not develop diabetes or insulitis. To further explore the role of Fas, adoptive transfer experiments were performed. When splenocytes were transferred from diabetic NOD, male NOD-+/+ and NOD-+/lpr developed diabetes with the incidence of 89 and 83%, respectively, whereas NOD-lpr/lpr did not show glycosuria by 12 wk after transfer. Severe mononuclear cell infiltration was revealed in islets of NOD-+/+ and NOD-+/lpr, whereas islet morphology remained intact in NOD-lpr/lpr. These results suggest that Fas-mediated cytotoxicity is required to initiate beta cell autoimmunity in NOD mice. Fas-Fas ligand system might be critical for autoimmune beta cell destruction leading to IDDM.

Adoptive Transfer↗
PubMed1997

Histopathologic study of the pancreas shows a characteristic lymphocytic infiltration in Japanese patients with IDDM.

We examined at autopsy 47 cases (22 males and 25 females) of insulin-dependent diabetes mellitus (IDDM) from 21 hospitals in Japan to clarify the pathological changes that occur in the pancreas vs. those in control patients. The mean age was 39.7 +/- 13.9 (mean +/- SD) years, and the duration of IDDM from clinical onset was 13.1 +/- 6.5 years. Causes of death included renal complications, infections, acute diabetic complications such as ketoacidosis or hyper- or hypoglycemic coma, and atherosclerotic disease. This study revealed noticeable decreases in the islet area and beta cell area, and a slight decreases in the alpha cell area and preservation of the number of islets. Insulitis was found in only 1 case, representing 25% of the cases with a duration of IDDM of one year or less. Lymphocytic infiltration of the exocrine gland was seen in 22 cases (46.8%). Predominant phenotypes of the lymphocytes were T lymphocytes and macrophages. Fibrosis, fatty change and atrophy were also found. Although this is not a strictly age- and sex-matched study, the high incidence of lymphocytic infiltration of the exocrine pancreas indicates that the exocrine tissue as well as beta cells is the target of immune reactions in Japanese patients with IDDM.

Adolescent↗
PubMed1997

Demonstration of two different processes of beta-cell regeneration in a new diabetic mouse model induced by selective perfusion of alloxan.

To clarify the regeneration process of pancreatic beta-cells, we established a new mouse model of diabetes induced by selective perfusion of alloxan after clamping the superior mesenteric artery. In this model, diabetes could be induced by the destruction of beta-cells in alloxan-perfused segments, while beta-cells in nonperfused segments were spared. Intraperitoneal glucose tolerance tests showed glucose intolerance, which gradually ameliorated and was completely normalized in 1 year with a concomitant increase of insulin content in the pancreas. Histological examination showed neo-islet formation in the alloxan-perfused segment and the proliferation of spared beta-cells in the nonperfused segment. In the alloxan-perfused segment, despite a marked reduction of islets in size and number at an early stage, both the number of islets, including islet-like cell clusters (ICCs), and the relative islet area significantly increased at a later stage. Increased single beta-cells and ICCs were located in close contact with duct cell lining, suggesting that they differentiated from duct cells and that such extra-islet precursor cells may be important for beta-cell regeneration in beta-cell-depleted segment. In addition to beta-cells, some nonhormone cells in ICCs were positive for nuclear insulin promoter factor 1, which indicated that most, if not all, nonhormone cells positive for this factor were beta-cell precursors. In the nonperfused segment, the islet area increased significantly, and the highest 5-bromo-2-deoxyuridine-labeling index in beta-cells was observed at day 5, while the number of islets did not increase significantly. This indicated that the regeneration of islet endocrine cells occurs mostly through the proliferation of preexisting intra-islet beta-cells in the nonperfused segment. In conclusion, the regeneration process of beta-cells varied by circumstance. Our mouse model is useful for studying the mechanism of regeneration, since differentiation and proliferation could be analyzed separately in one pancreas.

Alloxan↗
PubMed1996

Islet-infiltrating t lymphocytes in insulin-dependent diabetic patients express CD80 (B7-1) and CD86 (B7-2).

Insulin-dependent diabetes mellitus (IDDM) results mainly from T cell mediated pancreatic beta cell destruction. To fully activate antigen specific T cells, current evidence suggests that two signals are required. One signal is delivered via the antigen specific T cell receptor (TCR) when engaged by major histocompatibility complex presented antigen (MHC:Ag), the other via the T cell's CD28 when engaged by CD80/86. Recent studies have demonstrated that transgenic mice expressing CD80 on their pancreatic beta cells are susceptible to autoimmune beta cell destruction. To further explore whether CD80/86 expression plays a role in IDDM pathogenesis, we analysed pancreatic biopsy specimens from 16 recent-onset IDDM patients (13 men and 3 women; age 29.7 +/- 8.8 years) for CD80/86 expression. While no biopsy revealed any islet cell specific CD80 or CD86 expression, biopsies from six of the nine patients with insulitis revealed both CD80 and CD86 expression on the islet infiltrating cells. Triple immunofluorescent staining for CD80/86, CD3, and glucagon revealed that the CD80/86-positive cells were also CD3-positive. Of the CD3-positive cells, 19.4% expressed CD80 and 21.7% expressed CD86. CD80 and CD86-positive cells were similarly distributed throughout the inflamed islets. These data suggest that CD28 engagement with CD80/86 may play a pathogenic role in the beta cell destruction underlying IDDM.

Adult↗
PubMed1996

Spinal epidural abscess associated with epidural anesthesia: gadolinium-enhanced magnetic resonance imaging and its usefulness in diagnosis and treatment.

A case of spinal epidural abscess following epidural anesthesia is described. Gadolinium-enhanced magnetic resonance images were essential in diagnosis of the abscess without frank pus formation, in defining the extension of the infection, and in assessing the therapeutic effect. The patient was successfully treated non-operatively before neurological symptoms developed and full recovery was achieved.

Abscess↗
PubMed1996

High prevalence of antibodies to glutamic acid decarboxylase in comparison to islet cell antibodies in patients with long-standing insulin-dependent diabetes mellitus.

To elucidate the clinical significance of antibodies to glutamic acid decarboxylase (GAD Ab) compared to islet cell antibodies (ICA) in recent-onset and long-standing insulin-dependent diabetes mellitus (IDDM). We examined GAD Ab and ICA in 29 recent-onset and 85 long-standing patients with IDDM. GAD Ab was detected by a radioimmunoassay kit using purified pig brain GAD as an antigen. The prevalence of GAD Ab in the recent-onset diabetic patients was 55.2%, slightly lower than that of ICA (65.5%). In contrast, the prevalence of GAD Ab in long-standing diabetic patients was 42.4%, which was significantly higher than that of ICA (23.5%) (p < 0.01). GAD Ab were consistently detected in approximately 40% of patients with long-standing disease, while ICA decreased according to duration of disease. The GAD Ab titer in ICA-positive patients (mean +/- SD, 1588.2 +/- 6755.1; range, 6-38574) was significantly higher than that in ICA-negative patients (mean +/- SD, 13.4 +/- 17.9; and range, 5-72 units) (p < 0.001). These findings suggest that GAD Ab are more useful than ICA to know participation of immune disorders in long-standing patients with IDDM.

Adult↗
PubMed1995

Mitochondrial DNA mutations in pancreatic biopsy specimens from IDDM patients.

We investigated the contribution of mitochondrial DNA mutations to the pathogenesis of IDDM by analyzing mitochondrial DNA in pancreatic biopsy specimens and peripheral blood cells from 18 patients with newly-diagnosed IDDM. All patients presented with typical abrupt onset of diabetes and ketosis on initial examination. Point mutations at nucleotides 3243, 3271 and 8344 were assayed by polymerase chain reaction and restriction fragment length polymorphism analysis or by mismatch-primer analysis. A common large deletion from nucleotides 8483-13459 was analyzed by a primer shift method. All of these mutations are known to be pathogenic mutations. However, none of the mitochondrial DNA mutations were detected in any of 18 IDDM patients. Several types of mitochondrial DNA mutation have been identified in the peripheral blood cells in some patients with non-insulin-dependent diabetes mellitus as well as in some with IDDM, however, our results suggest that abrupt-onset IDDM does not correlate with any of the known mitochondrial DNA mutations.

Adolescent↗
PubMed1995

Autoimmune endocrine disease induced by recombinant interferon-alpha therapy for chronic active type C hepatitis.

To elucidate the role played by interferon-alpha (IFN alpha) in the pathogenesis of autoimmune endocrine disease, we determined the autoantibody status, thyroid function test results, hemoglobin-A1c levels, and clinical symptoms of 58 patients who received IFN alpha for treatment of chronic active type C hepatitis. Each patient was treated for 6 months with a total dose of 391 +/- 140 x 10(6) U (mean +/- SD). Thyroid microsomal and/or thyroglobulin antibodies newly appeared or were increased in titer in 6 patients, 2 of whom developed hypothyroidism during IFN alpha therapy. Neither islet cell antibodies nor insulin-dependent diabetes mellitus developed during IFN alpha therapy, although hemoglobin-A1c levels were increased in 2 patients. One patient became positive for antimitochondrial antibodies, and another patient with preexisting antimitochondrial antibodies also manifested deterioration in liver function test results. Parietal cell antibodies and smooth muscle cell antibodies were the most frequent newly developed antibodies in 7 patients. Adrenal medullary cell antibodies and nuclear antibodies newly developed in 2 and 1 patients, respectively. At least 1 of 8 autoantibodies newly appeared in 19 patients (32.8%) and hypothyroidism developed in 2 patients (3.4%) during IFN alpha therapy. On the other hand, in 19 age- and sex-matched patients who did not receive IFN alpha, no autoantibody appeared, and no autoimmune disease developed during a follow-up period of 3 months. These findings suggest that IFN alpha acts as an immunomodulatory agent, inducing autoantibody production and the development of autoimmune disease in susceptible patients. Special attention should be paid to the development of hypothyroidism during IFN alpha therapy.

Adult↗
PubMed1994

Occurrence of IDDM during interferon therapy for chronic viral hepatitis.

We report a case of IDDM which occurred during interferon therapy for chronic hepatitis. A 31-year-old man intermittently received 2.5 x 10(8) units of alpha-IFN and 1 x 10(8) units of beta-IFN for treatment of chronic viral hepatitis type B. Four years after the beginning of IFN therapy, he acutely developed moderate hyperglycemia and severe ketonuria with positive islet cell antibody, and then 28 units/day of insulin injection was started. After the start of insulin therapy, there was a remission period for about 3 years but insulin-dependency recurred thereafter. The clinical course of this case indicates that IFN therapy precedes IDDM. During and after IFN therapy we should consider the possibility of occurrence of IDDM as well as other autoimmune diseases and observe the clinical course carefully.

Adult↗
PubMed1993

Mononuclear cell infiltration and its relation to the expression of major histocompatibility complex antigens and adhesion molecules in pancreas biopsy specimens from newly diagnosed insulin-dependent diabetes mellitus patients.

We examined pancreas biopsy specimens from 18 newly diagnosed insulin-dependent diabetes mellitus (IDDM) patients to elucidate the mechanism underlying beta cell destruction. Pancreas islets were seen in all patients and insulitis in eight patients. Infiltrating mononuclear cells consisted of CD4+T, CD8+T, B lymphocytes, and macrophages. Among them, CD8+T lymphocytes were predominant and macrophages followed. The expression of MHC class I antigens was increased in islet and endothelial cells in nine patients. MHC class II expression was increased in endothelial cells of the same patients. The expression of intercellular adhesion molecule-1 was increased in endothelial cells in two of the nine patients with MHC hyperexpression; in one of them, lymphocyte function-associated antigen-3 expression was also increased. Out of the eight patients with insulitis, seven showed MHC class I hyper-expression, whereas 2 of the 10 patients without insulitis showed the phenomenon (P < 0.05). The relation between insulitis and the hyperexpression of adhesion molecules was not evident. In conclusion, we revealed the close relation between CD8+T lymphocyte-predominant insulitis and MHC class I hyperexpression in islet cells. This suggests that infiltrating CD8+T lymphocytes recognize islet autoantigens in association with increased MHC class I molecules and act as major effector cells in autoimmune response against islet cells in IDDM pancreases. The role of adhesion molecules in the pathogenesis of IDDM still remains to be elucidated.

Adolescent↗
PubMed1992

[Assessment of autonomic nervous function in impotence using sweat response induced by intradermal injection of acetylcholine].

It is important to evaluate the autonomic nervous function which controls penile erection. One method utilizes intradermal injection of acetylcholine to produce localized sweat response. The sweat response depends on the peripheral autonomic nervous supply. Therefore, the response can be used to detect peripheral autonomic nervous dysfunction. We tried to evaluate the peripheral autonomic dysfunction in 29 impotence using a sweat spots test. We classified the 29 impotence into 6 groups with standard tests such as the papaverine test, nocturnal penile tumescence monitoring, recordings of bulbocavernous reflex, etc. The results were as follows: psychogenic IMP; 8, neurogenic IMP; 8, arterial insufficiency; 5, corporeal veno-occlusive insufficiency; 6 neurogenic with arterial insufficiency; 1, and neurogenic with corporeal veno-occlusive insufficiency; 1. The score of sweat spots test was 25.3 +/- 10.9, being in normal, nineteen severe in 3 and slightly abnormal in 7. Many cases of severe and slightly abnormal patients were DM patients classified into neurogenic IMP. We found 2 cases that were not detected by bulbocavernous reflex but found to be abnormal by sweat spots test. Therefore we conclude that this test effective to detect the autonomic nervous dysfunction in impotence.

Acetylcholine↗