M. Knip

A Prospective Study of the Role of Coxsackie B and Other Enterovirus Infections in the Pathogenesis of IDDM

Coxsackievirus B infections have been associated with clinical manifestation of insulin-dependent diabetes mellitus (IDDM) in several studies, but their initiating role in the slowly progressing β-cell damage is not known. This is the first prospective study designed to assess the role of coxsackie B and other enterovirus infections in the induction and acceleration of this process. Three separate series were studied: 1) an intrauterine exposure series comprising 96 pregnant mothers whose children subsequently manifested IDDM and 96 control mothers whose children remained nondiabetic; 2) a cohort of 22 initially unaffected siblings of diabetic children who were followed until they developed clinical IDDM (mean observation time, 29 months) and 110 control siblings who remained nondiabetic; 3) a case-control series comprising 90 children with newly diagnosed IDDM and 90 control subjects. Enterovirus infections were identified on the basis of significant increases in serum IgG, IgM, or IgA class antibodies against a panel of enterovirus antigens (capture radioimmunoassay). Enterovirus antibodies were significantly elevated in pregnant mothers whose children subsequently manifested IDDM, particularly in cases in which IDDM appeared at a very young age, before the age of 3 years (P < 0.005). Serologically verified enterovirus infections were almost two times more frequent in siblings who developed clinical IDDM than in siblings who remained nondiabetic (mean, 1.0 vs. 0.6 infections/follow-up year; P < 0.001). This difference was seen both close to the diagnosis of IDDM and several years before diagnosis. Up to 19% (10 of 52) of the infections in prediabetic siblings were associated with increases in islet cell antibody (ICA) levels, and 83% (10 of 12) of ICAs increase with enterovirus infections. The corresponding figures in control siblings were 3% (5 of 185, P < 0.001) and 38% (5 of 13, Ns). IgM class enterovirus antibodies were slightly elevated in young children (<3 years old)with newly diagnosed IDDM (P < 0.05), but not in older patients. These observations suggest that exposures to enterovirus infections, both in utero and in childhood, are able to induce β-cell damage and lead to clinical IDDM after a varying subclinical period.

Autoantibodies to glutamic acid decarboxylase in patients with therapy-resistant epilepsy

Background: Autoantibodies to glutamic acid decarboxylase (GAD-A) are present in type 1 diabetes and stiff man syndrome (SMS), and have also been reported in cerebellar ataxia. Epilepsy was present in 4 of 19 patients with SMS and GAD-A, implying that epilepsy sometimes is associated with anti-GAD autoimmunity. Methods: The authors investigated the prevalence of GAD-A in patients with therapy-resistant localization-related epilepsy (n = 51) and generalized epilepsy (n = 49) by a radiobinding assay. The positive samples were confirmed by immunohistochemistry and immunoblotting of recombinant human GAD65. Results: GAD-A were found in eight patients with localization-related epilepsy, whereas none of the patients with generalized epilepsy, other neurologic disorders (n = 38), or the control subjects (n = 48) had GAD-A. Two patients had high levels of GAD-A, similar to SMS, whereas six patients had significantly lower titers, characteristic of type 1 diabetes. The two patients with high levels of GAD-A had GAD-A both in serum and CSF by immunohistochemistry and immunoblotting. Both of them had longstanding therapy-resistant temporal lobe epilepsy but did not have diabetes. One had a history of autoimmune disease, whereas the other had serologic evidence of multiple autoantibodies without any clinical signs of autoimmune disease. Conclusions: GAD autoimmunity may be associated with refractory localization-related epilepsy.

Epidemiology of childhood diabetes mellitus in Finland-background of a nationwide study of type 1 (insulin-dependent) diabetes mellitus

SummaryA nationwide study of childhood Type 1 (insulin-dependent) diabetes mellitus was established in 1986 in Finland, the country with the highest incidence of this disease worldwide. The aim of the project called “Childhood Diabetes in Finland” is to evaluate the role of genetic, environmental and immunological factors and particularly the interaction between genetic and environmental factors in the development of Type 1 diabetes. From September 1986 to April 1989, 801 families with a newly-diagnosed child aged 14 years or younger at the time of diagnosis were invited to participate in this study. The vast majority of the families agreed to participate in the comprehensive investigations of the study. HLA genotypes and haplotypes were determined in 757 families (95%). Our study also incorporates a prospective family study among non-diabetic siblings aged 3–19 years, and two case-control studies among the youngonset cases of Type 1 diabetes. During 1987–1989, the overall incidence of Type 1 diabetes was about 35.2 per 100,000 per year. It was higher in boys (38.4) than in girls (32.2). There was no clear geographic variation in incidence among the 12 provinces of Finland. Of the 1,014 cases during these 3 years only six cases were diagnosed before their first birthday. The incidence was high already in the age group 1–4-years old: 33.2 in boys and 29.5 in girls. Of the 801 families 90 (11.2%) were multiple case families, of which 66 had a parent with Type 1 diabetes at the time of diagnosis of the proband. The prevalence of Type 1 diabetes in the parents of these newly-diagnosed diabetic children was higher in fathers (5.7%) than in mothers (2.6%).

IA-2 antibodies - a sensitive marker of IDDM with clinical onset in childhood and adolescence

Summary To study the relationship of IA-2 antibodies (IA-2A) to other autoantibodies and genetic risk markers in insulin-dependent diabetes mellitus (IDDM), 758 children and adolescents younger than 15 years of age (mean age 8.4 years) with newly diagnosed diabetes were analysed for IA-2A, GAD antibodies (GADA) and insulin autoantibodies (IAA) with radiobinding assays, for islet cell antibodies (ICA) with immunofluorescence and for HLA DR alleles by serology. IA-2A were detected in 85.9 % of cases with no association with gender or age. An overwhelming majority of the patients (71.3 %) tested positive for three or more antibodies, and 90.7 % for at least two. Fifty-four subjects (7.1 %) had one antibody detectable, whereas only 2.1 % of the patients tested negative for all four. A higher proportion of patients was positive for IA-2A and/or GADA than for ICA alone (95.5 vs 84.2 %, p < 0.001). The prevalence and level of IA-2A were increased in cases carrying HLA DR4/non-DR3 compared with other DR combinations. The results indicate that almost all patients with newly diagnosed childhood IDDM can be identified by screening with these four autoantibodies. The combination of IA-2A and/or GADA had a higher sensitivity for IDDM than ICA alone. The close association between IA-2A and HLA DR4, the strongest single allele predisposing to IDDM, suggests that IA-2A may be a more specific marker of beta-cell destruction than GADA, which have been shown to associate with the DR3 allele and thyroid autoimmunity. [Diabetologia (1998) 41: 424–429]

The role of insulin in clustering of serum lipids and blood pressure in children and adolescents

SummaryIn adults hyperinsulinaemia is associated with an atherogenic risk profile including obesity, low levels of HDL-cholesterol, high levels of triglycerides and elevated blood pressure. To examine these associations in the young we studied the cross-sectional relationships of insulin with obesity indices (body mass index, subscapular skinfold thickness), serum lipids and blood pressure in 1,865 children, adolescents and young adults aged 6–24 years. We also used longitudinal data to study the value of a single insulin measurement to predict high risk factor levels and clustering of multiple risk factors after a 6-year follow-up. In cross-sectional analyses the levels of triglycerides, HDL-cholesterol, systolic blood pressure and obesity indices were usually significantly different across the quartiles of fasting insulin in both sexes among children, adolescents and young adults. In general, no associations were seen with total cholesterol or LDL-cholesterol. In prospective analysis elevated baseline insulin was related to the incidence of hypertriglyceridaemia (≥95th percentile) at the follow-up. This relationship persisted even after adjustments for baseline obesity or 6-year change in obesity status. Moreover, baseline insulin concentration was higher in subjects who subsequently showed clustering of high triglycerides, low HDL-cholesterol and high systolic blood pressure levels at the follow-up. We conclude that high fasting insulin levels measured in children and adolescents predict the development of hypertriglyceridaemia years later. In addition, high insulin levels seem to precede the development of a potentially atherogenic risk factor profile including low HDL-cholesterol, high triglycerides and high systolic blood pressure.

Enterovirus RNA in serum is a risk factor for beta‐cell autoimmunity and clinical type 1 diabetes: A prospective study

Recent prospective studies have documented serologically an increased frequency of enterovirus infections in prediabetic children, indicating that these infections may initiate and accelerate the beta‐cell damaging process several years before the clinical manifestation of type 1 diabetes. The aim of the present study was to establish whether these serological findings would be supported by the detection of enterovirus RNA in a unique prospective series of sera collected from prediabetic children 0–10 years before the manifestation of clinical type 1 diabetes. Reverse transcription followed by polymerase chain reaction employing highly conserved primers among enteroviruses were used to amplify enteroviral sequences. Viral RNA was found in 22% (11/49) of follow‐up samples from prediabetic children but in only 2% (2/105) of those from controls (OR 14.9, P < 0.001). Persisting RNA positivity was not observed in any of these children. The presence of enterovirus RNA was associated with concomitant increases in the levels of autoantibodies against islet cells (OR 21.7, P < 0.01) and glutamic acid decarboxylase (OR 15.4, P < 0.05), but not in the levels of antibodies against insulin or the tyrosine phosphatase‐like IA‐2 protein. In contrast to the prediabetic children, those with newly diagnosed type 1 diabetes were negative for enterovirus RNA. The results thus complement previous serological data, suggesting that enterovirus infections are an important risk factor underlying type 1 diabetes and associated with the induction of beta‐cell autoimmunity even years before symptoms appear. J. Med. Virol. 61:214–220, 2000.

Reproductive effects of valproate, carbamazepine, and oxcarbazepine in men with epilepsy

Background: Recent observations have indicated that reproductive endocrine disorders are common among women taking valproate (VPA) for epilepsy, but it is not known whether respective abnormalities develop in men taking VPA for epilepsy. Carbamazepine (CBZ) may induce endocrine disorders in men with epilepsy, but the endocrine effects of oxcarbazepine (OXC) are not known. Methods: Reproductive endocrine function was evaluated in 90 men taking VPA (n = 21), CBZ (n = 40), or OXC (n = 29) as monotherapy for epilepsy and in 25 healthy control men. Results: Twelve men (57%) taking VPA had increased serum androgen levels. The mean serum level of androstenedione was high in patients taking VPA. Serum levels of dehydroepiandrosterone sulfate were low, and serum concentrations of sex hormone–binding globulin (SHBG) were high in men taking CBZ. The endocrine effects of OXC seemed to be dose-dependent, because serum hormone levels were normal in patients with low OXC doses (<900 mg/day), but serum concentrations of testosterone, gonadotropins, and SHBG were high in patients with a daily OXC dose ≥900 mg. Conclusions: VPA increases serum androgen concentrations in men with epilepsy. The endocrine effects of CBZ and OXC were different, because CBZ appears to decrease the bioactivity of androgens, whereas OXC does not.

Valproate-induced hyperandrogenism during pubertal maturation in girls with epilepsy.

Valproate is effective for treatment of a variety of seizure types both in adults and in children with epilepsy, but it induces obesity and polycystic ovaries in a considerable proportion of adult women, particularly when the medication is started before the age of 20. In the present study we evaluated reproductive endocrine function in 41 girls, 8 to 18 years old, taking valproate for epilepsy and in 54 healthy control girls. Among the girls taking valproate, 16 were prepubertal, 11 were pubertal, and 14 were postpubertal, and the corresponding numbers were 20, 13, and 21 in the control group. The mean serum testosterone concentrations of prepubertal, pubertal, and postpubertal girls taking valproate were significantly higher than those of the control girls at the same pubertal stage. Hyperandrogenism, defined as serum testosterone levels higher than the mean + 2SD in the control girls at the same pubertal stage, was seen in 38% of prepubertal, 36% of pubertal, and 57% of postpubertal girls taking valproate. In addition, postpubertal girls taking valproate were more obese than the controls and the mean serum insulin‐like growth factor binding protein‐1 concentration of pubertal and postpubertal hyperandrogenic girls taking valproate was lower than in valproate‐treated girls without hyperandrogenism. Valproate may induce hyperandrogenism in girls with epilepsy during the sensitive period of pubertal maturation, and the frequency of hyperandrogenism increases with pubertal development. This emphasizes the importance of careful endocrine observation of girls taking valproate for epilepsy. Ann Neurol 1999;45:444–450

Population-based genetic screening for the estimation of Type 1 diabetes mellitus risk in Finland : selective genotyping of markers in the HLA-DQB1, HLA-DQA1 and HLA-DRB1 loci

Aims To improve sensitivity and specificity of the diabetes risk assessment of the population‐based genetic screening used in the Finnish Diabetes Prediction and Prevention (DIPP) trial.

Autoantibodies associated with Type I diabetes mellitus persist after diagnosis in children

Summary To study the persistence of Type I (insulin-dependent) diabetes mellitus associated autoantibodies and their relation to genetic risk markers and clinical characteristics of the disease after clinical manifestation, serum samples were obtained from 90 children and adolescents at diagnosis and 2, 5 and 10 years later. The samples were analysed for islet cell antibodies (ICA) by immunofluorescence and for antibodies to glutamic acid decarboxylase (GADA), intracellular portion of the protein tyrosine phosphatase related IA-2 antigen (IA-2A) and insulin autoantibodies by specific radiobinding assays. Of the subjects tested 79 % were positive for IA-2A at diagnosis, 62 % for GADA, 81 % for ICA and 28 % for insulin autoantibodies, but the prevalence of IA-2A, GADA and ICA decreased substantially as a function of increasing duration of the disease (p < 0.05 or less), their levels following the same pattern (p < 0.001 for all three autoantibodies). Two thirds of the subjects still tested positive for at least one autoantibody specificity after the first 10 years of the disease and 42 % had two or three antibodies detectable. An increase over the initial antibody concentrations after the diagnosis was seen more often for GADA than for ICA (p < 0.001) or IA-2A (p < 0.05). In conclusion, autoantibodies associated with Type I diabetes appear to persist longer than expected after manifestation of the clinical disease, possibly due to small scale continuous beta-cell regeneration after diagnosis or to structural and/or functional mimicry between exogenous proteins and beta-cell antigens or both. [Diabetologia (1998) 41: 1293–1297]