Diabetologia

Kallmann, B. A.; Lampeter, E. F.; Hanifi-Moghaddam, P.; Hawa, M.; Leslie, R. D. G.; Kolb, H.

doi: 10.1007/s001250051274pmid: 10447519

Aims/hypothesis . The search for T-cell reactions that are associated with disease in Type I (insulin-dependent) diabetes mellitus is severely hampered because control groups cannot be matched for relevant immune response genes. We therefore compared T-cell responses between identical twins discordant for Type I diabetes. Methods . Pairs of monozygotic twins ( n = 17) discordant for Type I diabetes were studied. Cultures were set up from whole blood immediately after sampling and cells were challenged with human recombinant hsp60, with the mitogen phytohaemagglutinin or with the staphylococcal superantigen. Supernatants were removed after 48 or 96 h and analysed for T-helper1 type cytokines interferon- γ , TNFα and T-helper2 type cytokines IL-4, IL-10 by sandwich-ELISA. Results . The height of the T-helper1 type cytokine response to hsp60, phytohaemagglutinin or staphylococcal enterotoxin B did not show disease association, i. e. it was similar between discordant twins. In contrast, the production of T-helper2 type cytokines differed between discordant twins. The IL-10 response to hsp60 was higher in twins at low disease risk (islet cell antibody-negative) than in their diabetic cotwins ( p < 0.01), as was the IL-4 response to phytohaemagglutinin ( p < 0.05). No difference was seen in the cytokine response between islet cell antibody-positive twins and their diabetic cotwins. Conclusions/interpretation . The data indicate an association between T-helper2 type cytokine secretion patterns and disease or disease risk. (Diabetologia (1999) 42: 1080–1085)

,

doi: 10.1007/s001250051283pmid: 10447528

Movassat, J.; Portha, B.

doi: 10.1007/s001250051277pmid: 10447522

Aims / hypothesis . In the Goto-Kakisaki rat, a genetic model of non-insulin dependent diabetes, we have recently reported that as early as fetal age, there is a restriction of the beta-cell mass which is maintained in the adult animal and is detectable before the onset of hyperglycaemia. It is therefore important to investigate the beta-cell growth potential in young Goto-Kakisaki rats. Methods . We have studied in 4 and 7-day-old Goto-Kakisaki neonates: 1. the in vivo replication rate of the beta cell; 2. the occurrence of beta-cell apoptosis; 3. the effectiveness of beta-cell regeneration after damage caused by neonatal treatment with streptozotocin. Results . The replication rate in vivo of beta cells and the beta-cell apoptosis were similar in untreated Wistar and Goto-Kakisaki neonates on days 4 and 7 whereas the total beta-cell masses were reduced to 50 % in the Goto-Kakisaki groups. Treatment with streptozotocin reduced the total beta-cell mass to the same extent in both Wistar and Goto-Kakisaki rats on day 4 compared with the corresponding normal values in Wistar and Goto-Kakisaki neonates. From day 4 to day 7, spontaneous beta-cell regeneration was manifest in both groups. Compared with the Wistar streptozotocin group, the net value of the beta-cell mass added during this period was more limited in the Goto-Kakisaki streptozotocin group, despite the replication activity of the residual beta cells being increased in this group to the same extent as in the Wistar streptozotocin group. Conclusion / interpretation . We therefore suggest: 1. that the reduced beta-cell mass in the untreated neonatal Goto-Kakisaki rat does not appear to reflect a reduction in the rate of beta-cell replication or an increased beta-cell death by apoptosis but is potentially due to an impaired rate of beta-cell neogenesis, and 2. that beta-cell regeneration can be reactivated after streptozotocin insult in the neonatal Goto-Kakisaki rat, although to a lesser extent compared with that in streptozotocin-treated Wistar neonates. (Diabetologia (1999) 42: 1098–1106)

Cameron, N. E.; Cotter, M. A.; Jack, A. M.; Basso, M. D.; Hohman, T. C.

doi: 10.1007/s001250051280pmid: 10447525

N. E. Cameron M. A. Cotter A. M. Jack M. D. Basso T. C. Hohman Department of Biomedical Sciences, University of Aberdeen, Aberdeen, Scotland, UK GB Wyeth-Ayerst Research, Princeton, New Jersey, USA US Abstract Aims//hypothesis . Increased protein kinase C activity has been linked to diabetic vascular complications in the retina and kidney, which were attenuated by protein kinase C antagonist treatment. Neuropathy has a vascular component, therefore, the aim was to assess whether treatment with WAY151 003 or chelerythrine, inhibitors of protein kinase C regulatory and catalytic domains respectively, could correct nerve blood flow, conduction velocity, Na + ,K + -ATPase, and glutathione deficits in diabetic rats. Methods . Diabetes was induced by streptozotocin. Sciatic nerve conduction velocity was measured in vivo and sciatic endoneurial perfusion was monitored by microelectrode polarography and hydrogen clearance. Glutathione content and Na + ,K + -ATPase activity were measured in extracts from homogenised sciatic nerves. Results . After 8 weeks of diabetes, sciatic blood flow was 50 % reduced. Two weeks of WAY151 003 (3 or 100 mg/kg) treatment completely corrected this deficit and chelerythrine dose-dependently improved nerve perfusion. The inhibitors dose-dependently corrected a 20 % diabetic motor conduction deficit, however, at high doses ( > 3.0 mg/kg WAY151003; > 0.1 mg/kg chelerythrine) conduction velocity was reduced towards the diabetic level. Sciatic Na + ,K + -ATPase activity, 42 % reduced by diabetes, was partially corrected by low but not high dose WAY151 003. In contrast, only a very high dose of chelerythrine partially restored Na + ,K + -ATPase activity. A 30 % diabetic deficit in sciatic glutathione content was unchanged by protein kinase C inhibition. The benefits of WAY151 003 on blood flow and conduction velocity were blocked by nitric oxide synthase inhibitor co-treatment. Conclusion/interpretation . Protein kinase C contributes to experimental diabetic neuropathy by a neurovascular mechanism rather than through Na + ,K + -ATPase defects. (Diabetologia (1999) 42: 1120–1130)

Shaw, J. E.; Hodge, A. M.; de Courten, M.; Chitson, P.; Zimmet, P. Z.

doi: 10.1007/s001250051269pmid: 10447514

J. E. Shaw A. M. Hodge M. de Courten P. Chitson P. Z. Zimmet International Diabetes Institute, Melbourne, Australia AU Ministry of Health, Port Louis, Mauritius MU Abstract Aims/hypothesis . The aim of this study was to examine the possible link between isolated post-challenge hyperglycaemia (2-h post-challenge plasma glucose ≥ 11.1 mmol/l, and fasting plasma glucose < 7.0 mmol/l) and mortality. Methods . The data from three population based longitudinal studies (in Mauritius, Fiji and Nauru) were pooled and mortality rates were determined in 9179 people who were followed for between 5 and 12 years. Results . There were 595 people with previously diagnosed diabetes, and 799 with newly diagnosed diabetes, of whom 243 (31) had isolated post-challenge hyperglycaemia. In comparison with people without diabetes, people with isolated post-challenge hyperglycaemia had an increased risk of all-cause mortality (Cox proportional hazards ratio (95 % CI): 2.7 (1.8–3.9) – men; 2.0 (1.3–3.3) – women), and of cardiovascular mortality (2.3 (1.2–4.2) – men; 2.6 (1.3–5.1) – women). In addition, men with isolated post-challenge hyperglycaemia had a high risk of cancer death (8.0 (3.6–17.9)). Conclusion/interpretation. These data show that isolated post-challenge hyperglycaemia, which can only be identified by the 2-h glucose, is common, and at least doubles the mortality risk. This should be considered in the design of screening programmes that use only fasting glucose (Diabetologia (1999) 42: 1050–1054)

Sánchez-Soto, M. C.; Larrieta, M. E.; Vidaltamayo, R.; Hiriart, M.

doi: 10.1007/s001250051275pmid: 10447520

Aims/hypothesis. An isoform of glutamic acid decarboxylase, (GAD)65 has been identified as a pancreatic beta-cell autoantigen in Type I (insulin dependent) diabetes mellitus. We investigated the expression of GAD isoforms among single rat beta cells in culture, under different conditions and the correlation between GAD65 expression and insulin secretion-rate. Results . Independent of culture conditions, 100 % of fresh and cultured beta cells express GAD67. In contrast, considerable heterogeneity in GAD65 expression among single beta cells was observed. After 2 days in culture in 2.6 mmol/l glucose, only 24 % of the beta cells express GAD65. This percentage increases to 39 % in 5.6 mmol/l glucose and to 54 % and 56 % in 11.6 mmol/l and 20.6 mmol/l glucose, respectively. Moreover, reducing glucose concentration from 11.6 to 2.5 mmol/l for 2 days, reduces GAD65 expression by nearly 30 %. After 11 days in culture with 11.6 mmol/l glucose, 50 % of beta cells continue expressing GAD65, this percentage is further increased to nearly 75 % by including either nerve growth factor or dibutyryl cyclic AMP or both in the culture medium. When beta cells are challenged for 1 h with 20.6 mmol/l glucose, 67 % respond forming insulin-immunoplaques. More than two-thirds of insulin-secretors are GAD65-positive, in contrast to only 11 % of the non-secreting cells. Moreover, 87 % of beta cells that have a high insulin secretory rate express GAD65. Conclusion/interpretation . These results show that the most active beta cells, which secrete more insulin, also express GAD65 and that manipulating extracellular glucose may modify the expression of the enzyme and possibly the autoimmune attack in Type I diabetes. (Diabetologia (1999) 42: 1086–1092)

Kawano, Y.; Rincon, J.; Soler, A.; Ryder, J. W.; Nolte, L. A.; Zierath, J. R.; Wallberg-Henriksson, H.

doi: 10.1007/s001250051273pmid: 10447518

Y. Kawano J. Rincon A. Soler J. W. Ryder L. A. Nolte J. R. Zierath H. Wallberg-Henriksson Departments of Clinical Physiology, and Physiology and Pharmacology, Karolinska Institute, Karolinska Hospital, Stockholm, Sweden SE Abstract Aims/hypothesis . We have previously reported that hyperglycaemia activates glucose transport in skeletal muscle by a Ca 2+ -dependent pathway, which is distinct from the insulin-signalling pathway. The aim of this study was to explain the signalling mechanism by which hyperglycaemia autoregulates glucose transport in skeletal muscle. Methods . Isolated rat soleus muscle was incubated in the presence of various concentrations of glucose or 3- O -methylglucose and protein kinase C and phospholipase C inhibitors. Glucose transport activity, cell surface glucose transporter 1 and glucose transporter 4 content and protein kinase C translocation was determined. Results . High concentrations of 3- O -methylglucose led to a concentration-dependent increase in ( 3 H)-3- O -methylglucose transport in soleus muscle. Dantrolene, an inhibitor of Ca 2+ released from the sarcoplasmic reticulum, decreased the V max and the K m of the concentration-response curve. Protein kinase C inhibitors (H-7 and GF109203X) inhibited the stimulatory effect of high glucose concentrations on hexose transport, whereas glucose transport stimulated by insulin was unchanged. Incubation of muscle with glucose (25 mmol/l) and 3- O -methylglucose (25 mmol/l) led to a three fold gain in protein kinase C β 2 in the total membrane fraction, whereas membrane content of protein kinase Cα, β 1 , δ , ɛ and ϑ were unchanged. A short-term increase in the extracellular glucose concentration did not change cell surface recruitment of glucose transporter 1 or glucose transporter 4, as assessed by exofacial photolabelling with ( 3 H)-ATB-BMPA bis-mannose. Conclusion/interpretation. Protein kinase C β 2 is involved in a glucose-sensitive, Ca 2+ -dependent signalling pathway, which is possibly involved in the regulation of glucose transport in skeletal muscle. This glucose-dependent increase in 3- 0 -methylglucose transport is independent of glucose transporter 4 and glucose transporter 1 translocation to the plasma membrane and may involve modifications of cell surface glucose transporter activity. (Diabetologia (1999) 42: 1071–1079)

,

doi: 10.1007/s001250051284pmid: 10447529

,

doi: 10.1007/s001250051285pmid: 10447530

Rosenbauer, J.; Herzig, P.; von Kries, R.; Neu, A.; Giani, G.

doi: 10.1007/s001250051270pmid: 10447515

J. Rosenbauer P. Herzig R. von Kries A. Neu G. Giani Department of Biometrics and Epidemiology, Diabetes Research Institute at the Heinrich-Heine-University of Duesseldorf, Germany DE Institute of Social Paediatrics and Adolescent Medicine, Ludwig-Maximilians-University, Munich, Germany DE Children's Hospital, University of Tuebingen, Germany DE Abstract Aims/hypothesis . To estimate the national incidence of Type I (insulin-dependent) diabetes mellitus in children under 5 years of age in Germany and to analyse temporal, seasonal, and geographical patterns of the diabetes incidence. Methods . During 1993–1995 newly diagnosed subjects were prospectively registered by the hospital-based ’German Paediatric Surveillance Unit' with monthly inquiries in all paediatric departments in Germany. Level of ascertainment was estimated by capture-recapture-analysis using two independent regional data sources. Results . During 1993–1995 the national incidence was 8.10 (95 %-CI: 7.61, 8.61) per 100 000 person-years, ranging in-between lower rates in west European countries and higher rates in northern Europe. Degree of ascertainment was about 85 %. Male to female ratio was 1.11 (95 %-CI: 0.98, 1.25). Compared with results of previous regional studies in the east and the south-west of Germany a 3- and 1.3-fold incidence increase was observed, respectively. Multivariate Poisson regression analysis showed season, geographical region, and interactions of age at onset with sex and calendar year to be independent significant predictors of the incidence. Incidence variation by age was different between boys and girls. A significant incidence increase by calendar year was found in 3- and 4-year-old children only. In summer and fall the incidence was higher than in winter and springtime, in the northern parts of the country higher than in the southern parts. Conclusion/interpretation . This study reports first national incidence data of Type I diabetes in children under the age of 5 years in Germany. Observed marked temporal, seasonal, and geographical incidence variations strongly support the causal role of environmental factors in disease aetiology. (Diabetologia (1999) 42: 1055–1059)