Acute hyperinsulinism modulates plasma apolipoprotein B-48 triglyceride-rich lipoproteins in healthy subjects during the postprandial period.

The role of postprandial insulin in the regulation of postprandial lipid metabolism is still poorly understood. The roles of hyperinsulinemia and insulin resistance in the alteration of postprandial lipid metabolism are not clear either. To improve knowledge in this area, we submitted healthy men to acute hyperinsulinemia in two different ways. In the first study, we compared in 10 men the effects of four isolipidic test meals that induce different degrees of hyperinsulinemia on postprandial lipid metabolism. Three different carbohydrate sources were compared according to their glycemic indexes (GIs; 35, 75, and 100 for white kidney bean, spaghetti, and white bread test meals, respectively); the fourth test meal did not contain any carbohydrates. Postprandial plasma insulin levels were proportional to the GIs (maximal plasma insulin concentrations: 113 +/- 16 to 266 +/- 36 pmol/l). We found a strong positive correlation during the 6-h postprandial period between apolipoprotein (apo) B-48 plasma concentration and insulin plasma concentration (r2 = 0.70; P = 0.0001). In a second study, 5 of the 10 subjects again ingested the carbohydrate-free meal, but during a 3-h hyperinsulinemic- (550 +/- 145 pmol/l plasma insulin) euglycemic (5.5 +/- 0.8 mmol/l plasma glucose) clamp. A biphasic response was observed with markedly reduced levels of plasma apoB-48 during insulin infusion, followed by a late accumulation of plasma apoB-48 and triglycerides. Overall, the data obtained showed that portal and peripheral hyperinsulinism delays and exacerbates postprandial accumulation of intestinally derived chylomicrons in plasma and thus is involved in the regulation of apoB-48-triglyceride-rich lipoprotein metabolism, in the absence of insulin-resistance syndrome.

Specific deficiency of p56lck expression in T lymphocytes from type 1 diabetic patients.

Peripheral T lymphocyte activation in response to TCR/CD3 stimulation is reduced in type 1 diabetic patients. To explore the basis of this deficiency, a comprehensive analysis of the signal transduction pathway downstream of the TCR/CD3 complex was performed for a cohort of patients (n = 38). The main result of the study shows that T cell hyporesponsiveness is positively correlated with a reduced amount of p56(lck) in resting T lymphocytes. Upon CD3-mediated activation, this defect leads to a hypophosphorylation of the CD3zeta-chain and few other polypeptides without affecting the recruitment of ZAP70. Other downstream effectors of the TCR/CD3 transduction machinery, such as phosphatidylinositol 3-kinase p85alpha, p59(fyn), linker for activation of T cells (LAT), and phospholipase C-gamma1, are not affected. In some patients, the severity of this phenotypic deficit could be linked to low levels of p56(lck) mRNA and resulted in the failure to efficiently induce the expression of the CD69 early activation marker. We propose that a primary deficiency in human type 1 diabetes is a defect in TCR/CD3-mediated T cell activation due to the abnormal expression of the p56(lck) tyrosine kinase.

Humoral immunity against glutamic acid decarboxylase and tyrosine phosphatase IA-2 in Lambert-Eaton myasthenic syndrome.

Some beta-cell-specific autoantigens also are present in the central nervous system. Furthermore, stiff man syndrome, an autoimmune neurological disease, is frequently associated with diabetes and shares with this one an anti-GAD and IA-2 humoral immunoreactivity. We wondered whether these autoantibodies could be found in other neurological diseases with a present or supposed autoimmune origin. So, anti-GAD65 (GAD65A) and anti-IA-2 (IA-2A) autoantibodies were assayed in various neurological diseases. There was a higher prevalence of such antibodies in Lambert-Eaton myasthenic syndrome (LEMS) (GAD65A, 35%; IA-2A, 21%; double positivity, 18%) compared to amyotrophic lateral sclerosis (18%, 12%, and 12%, respectively) and multiple sclerosis (10%, 3%, and 3%, respectively). In LEMS, the humoral reaction was more frequent and/or appeared earlier in the paraneoplastic forms. The detection of such autoantibodies in patients with small-cell lung carcinoma (SCLC) without LEMS suggests that these autoantigens, GAD65 and IA-2, could be produced by SCLC tissue.

Oral insulin administration and residual beta-cell function in recent-onset type 1 diabetes: a multicentre randomised controlled trial. Diabète Insuline Orale group.

BACKGROUND: Oral administration of autoantigens can slow the progression of beta-cell destruction in non-obese diabetic mice. We investigated whether oral administration of recombinant human insulin could protect residual beta-cell function in recent-onset type 1 diabetes. METHODS: We enrolled 131 autoantibody-positive diabetic patients aged 7-40 years within 2 weeks of diagnosis (no ketoacidosis at diagnosis, weight loss <10%, polyuria for <6 weeks). They were randomly assigned 2.5 mg or 7.5 mg oral insulin daily or placebo for 1 year, in addition to subcutaneous insulin therapy. Serum C-peptide concentrations were measured in the fasting state and after stimulation, to assess beta-cell function. Autoantibodies to beta-cell antigens were assayed. Analyses were by intention to treat. FINDINGS: Baseline C-peptide and haemoglobin A1c concentrations were similar in the three groups. During follow-up, there were no differences between the groups assigned 2.5 mg or 7.5 mg oral insulin or placebo in subcutaneous insulin requirements, haemoglobin A1c concentrations, or measurements of fasting (mean at 12 months 0.18 [SD 0.17], 0.17 [0.17], and 0.17 [0.12] nmol/L) or stimulated C-peptide concentrations (glucagon-stimulated 0.39 [0.38], 0.37 [0.39], and 0.33 [0.24] nmol/L; meal-stimulated 0.72 [0.60], 0.49 [0.49], and 0.57 [0.51 nmol/L]. Neither age nor C-peptide concentration at entry influenced treatment effects. No differences were seen in the time-course or titres of antibodies to insulin, glutamic acid decarboxylase, or islet antigen 2. INTERPRETATION: At the doses used in this trial, oral administration of insulin initiated at clinical onset of type 1 diabetes did not prevent the deterioration of beta-cell function.

Dietary fat clearance in type V hyperlipoproteinaemia secondary to a rare variant of human apolipoprotein E: the apolipoprotein E3 (Arg 136-->Ser)

This present case report describes two siblings with severe type V hyperlipoproteinaemia, diagnosed very early in life and due to the combination of the common apolipoprotein (Apo) E2 allele and rare mutant variant of ApoE, ApoE3 (Arg 136-->Ser). Phenotyping of ApoE falsely identified E2/E2 phenotype. The presence of mutated ApoE was suspected on an unusual restriction polymorphism of a Hha 1 restriction site and confirmed by sequence analysis of the cloned polymerase chain reaction fragment of exon 4 and familial segregation study. The severity of the hypertriacylglycerolaemia was modulated by the lipid content of the diet. A low-fat diet enriched in medium-chain triacylglycerol (TAG) decreased but did not normalize plasma TAG levels in both affected patients of the pedigree. A standardized lipid-enriched test meal showed a marked impairment of TAG-rich lipoprotein (TRL) clearance, especially the exogeneous TRL bearing ApoB-48 which still represented 79% of total TRL 7 h after the fat load. Finally, differences between the male and female siblings with the existence of a consanguine relationship in their parents suggested the involvement of other genetic factors in modulating the severity of phenotypic expression. This observation reinforces the usefulness of genotyping of ApoE for the characterization of genetic hypertriacylglycerolaemia and selection of the appropriate diet and treatment.

Serum reg protein level is not related to the beta cell destruction/regeneration process during early phases of diabetogenesis in type I diabetes.

OBJECTIVE: In type I diabetes mellitus, early markers of beta cell damage are needed in order to detect the infraclinical development of the disease. The reg protein may be a good candidate, as the reg gene has been proposed to play a role in the pancreatic beta cell destruction/regeneration process during diabetogenesis in animal models of autoimmune diabetes. The aim of this study was to test the hypothesis whether serum reg protein level could be representative of either the destructive or regenerative process at the beta cell level during the early phases of type I diabetes in humans. DESIGN AND METHODS: We used a highly specific immunoassay to measure serum reg protein level in controls and in three groups of either diabetes prone or diabetic subjects: recently diagnosed diabetic patients, long-standing diabetic patients and islet cell antibody-positive non-diabetic subjects. RESULTS: We found no significant difference between the values observed in these three groups in comparison with control group (90.7+/-18.1ng/ml, 83.1+/-5.6ng/ml, 98.7+/-24.5ng/ml vs 85.5+/- 5.6ng/ml respectively). Moreover, when the insulin reserve was evaluated at 6 months in the recently diagnosed group, serum reg protein levels were not different between patients with or without residual insulin secretion (at onset: 103+/-42 vs 70.3+/-8. 5ng/ml respectively; at 6 months: 79.7+/-25.8ng/ml vs 81.6+/-15ng/ml respectively). In contrast, trypsin levels were significantly lower in every group of diabetic patients. Results were expressed as means +/- S.E.M. and groups compared by Student's t-test (P<0.05). CONCLUSIONS: We conclude that serum reg protein level cannot be used as a marker for the progression of the diabetogenic process in type I diabetes.

Constitutive impaired TCR/CD3-mediated activation of T cells in IDDM patients co-exist with normal co-stimulation pathways.

IDDM is a T cell-mediated autoimmune disease which is paradoxically associated with T cell functional deficiencies. The proliferative response of PBMC under CD3-, Vbeta2-, Vbeta8- and Vbeta7-stimulation was investigated in IDDM and NIDDM patients, non-diabetic first-degree relatives and control subjects. Despite normal surface expression of the TCR/CD3 complex, the TCR/CD3-mediated proliferation of PBMC from IDDM patients was significantly impaired compared to control subjects (P<0.05). This defect was specific for the autoimmune disease, constitutive and not linked to the class II MHC genotype, to metabolic disturbances or to presence of specific autoantibodies. Inefficient activation of T cells was not related to a lower capacity of CD28 to transduce co-stimulative signals because proliferative responses under CD2/CD28 stimulations were similar in IDDM and control groups. The IL-2/IL-2 receptor system was functional because unstimulated PBMC proliferated in response to increasing amounts of IL-2. Nevertheless, despite normal expression of CD25, addition of IL-2 did not normalize the proliferative defect linked to IDDM. In conclusion, excluding a faulty co-stimulation pathway, these results are in favour of a constitutive defect in the CD3/TCR transduction machinery, increasing sensitivity to apoptosis or anergy in T cells from IDDM patients.

Relationship between HLA-DQ and -DR genotypes and clinical characteristics in a French population of Type 1 diabetic patients.

AIMS: The present study was designed to look for a heterogeneity in the association between Type 1 diabetes mellitus (DM) and class II alleles of major histocompatibility complex (MHC) according to clinical presentation and C-peptide secretion during the first year of the disease, in a population living in south of France. METHODS: HLA DRB1 and DQB1 genotypes were determined in 129 Caucasoid patients with Type 1 DM and compared to a control group (n = 88). In a subgroup of 46 young adult diabetic patients, basal and postglucagon C-peptide secretion was followed during the first year of the disease (at 0, 1, 3, 6, 9 and 12 months). RESULTS: The two main haplotypes associated with Type 1 DM were DRB1*04DQB1*0302 and DRB1*03DQB1*02. The genotypes DRB1* 04DQB1 *0302/DRB1*04DQB1*0302 and DRB1 *03DQB1*02/DRB1*04DQB1* 0302 were associated with an early onset of diabetes, while homozygosity for DRB1*03DQB1*02 was characterized by later onset. Levels of residual insulin secretion in patients genotyped DRB1*03DQA1*0501DQB1* 02/DRB1* 04DQA1*0301DQB1*0302 were higher than in patients genotyped DRB1* 3DQA1*0501DQB1*02/DRB1*XDQA1*XDQB1*X or DRB1* XDQA1* XDQB1*X/DRB1*XDQA1*XDQB1*X. CONCLUSIONS: This study confirms some clinical heterogeneity of Type 1 DM linked to HLA DR and DQ genotypes, and leads to a paradoxical finding: DQB1*02/ DQB1*0302 combination predisposes to an early onset in the whole population but residual secretion of insulin disappears more slowly in a subgroup of young adults with recently diagnosed diabetes. These data suggest that interrelations between MHC genotype and diabetogenic process could be different at various ages of life.

Influence of obesity and body fat distribution on postprandial lipemia and triglyceride-rich lipoproteins in adult women.

We know that upper body obesity is associated with metabolic complications, but we don't know how regional body fat distribution influences postprandial lipemia in obese adults. Thus, this study explored the respective effects of android or gynoid types of obesity and fasting triglyceridemia on postprandial lipid metabolism and especially triglyceride-rich lipoproteins. Twenty-four obese and 6 lean normotriglyceridemic women (control), age 24-57 yr, were enrolled. Among obese women with an android phenotype, 9 exhibited normal plasma triglyceride levels (mean: 1.38 mmol/L) (NTAO), and 7 displayed a frank hypertriglyceridemia (mean: 2.40 mmol/L) (HTAO). The 8 patients with a gynoid phenotype had normal triglyceride levels (mean: 1.00 mmol/L) (GO). All were given a mixed test meal providing 40 g triglycerides. Serum and incremental chylomicron triglycerides 0-7 h areas under the curve (AUCs) as well as triglyceride levels in apoB-48-containing triglyceride-rich lipoprotein (TRLs) or chylomicrons were significantly higher in HTAOs and NTAOs than in GOs and controls postprandially. The size of chylomicron particles was bigger in controls and GOs than in HTAOs and NTAOs postprandially. Android obese subjects showed abnormally elevated fasting apoB-48 and apoB-100 triglyceride-rich lipoprotein (TRL) levels. Most abnormalities that were found correlated to plasma levels of insulin and apoC-III. In conclusion, an abnormal postprandial lipid pattern is a trait of abdominal obesity even without fasting hypertriglyceridemia.

Disorganization of thymic medulla precedes evolution towards diabetes in female NOD mice.

The thymic medulla is a complex microenvironment which plays a crucial role in central tolerance induction. Using a quantitative histological analysis of non-obese diabetic (NOD) mice, we show that the medulla undergoes several structural modifications during the course of the disease in NOD mice. Indeed, the majority of 70-day-old NOD mice show a scattering of medullary epithelial cells in the cortex which is associated with a reduction in the size of the medulla in heavily disorganized thymuses. The severity of this phenotype is shown to correlate with the subsequent appearance of diabetes in older female NOD mice. This trait is mainly controlled by non-major histocompatibility complex NOD genes since C57BL/6 H-2g(7) congenic mice have a normal medulla. It persists in conditions where effector lymphocytes that lead to diabetes are inhibited in periphery. These results suggest that primary alterations of the thymic stroma might play a role in the progression towards diabetes in NOD mice.

Study of serum big-insulin-like growth factor (IGF)-II and IGF binding proteins in two patients with extrapancreatic tumor hypoglycemia, using a combination of Western blotting methods.

Extrapancreatic tumor hypoglycemia (EPTH) is associated with increased amounts of high-molecular-weight precursor forms of insulin-like growth factor (IGF)-II ('big-IGF-II') that have a primary role in the pathophysiology of hypoglycemia. In the present study, using Western ligand and immunoblotting methods, we investigated IGF-binding proteins (IGFBPs), IGFBP-3 proteolysis and big-IGF-II in pre- and postoperative serum from two patients with EPTH due to benign pleural fibroma. In the preoperative serum, IGFBP-3 was reduced and IGFBP-2 was increased compared with that from an age-matched healthy control. IGFBP-3 proteolysis was dramatically reduced in one patient, whereas no major alteration was observed in the other (9% and 120% of control serum, respectively). IGFBPs progressively returned to a subnormal pattern in postoperative serum, whereas IGFBP- 3 proteolysis remained greater than in preoperative serum in both patients at days 14 and 90 after surgery. High-molecular-weight forms of IGF-II predominate in EPTH serum (65% and 57% of total IGF-II immunoreactivity in patients 1 and 2, respectively, compared with 2 5% in control serum). Two forms, of molecular mass 10 and 12 kDa ('standard big-IGF-II') were present in both EPTH and control sera, whereas two additional forms, of molecular mass 15 and 18 kDa ('big big-IGF-II') were observed in EPTH sera only. Big big-IGF-II represented 72% and 55% of total high-molecular-weight forms of IGF-II in the two EPTH sera, respectively. All big forms of IGF-II disappeared from the serum as early as 6 h after surgery. This study shows that combination of simple Western blotting methods, available routinely in most laboratories, should prove useful in providing reliable physiopathological information in EPTH.

[Food preferences in anorectic girls at the beginning of therapy]. / Etude des préférences alimentaires chez la jeune fille anorexique au début de la prise en charge thérapeutique.

To determine the eating habits of patients with anorexia nervosa, we compared a group of 21 anorectic girls satisfying DSM-III-R criteria (A: 19 +/- 6.6 years; 14.2 +/- 2 kg/m2) with 30 control girls (C: 19.8 +/- 3.3 years; 20.9 +/- 4.4 kg/m2). A standardised form listing 226 food items was used to assess their food preferences. For each food category except vegetables and fish, the medium rate of positive appreciation was lower in group A than in group C. However, a positive correlation was found between the two groups (except for dairy and diet products), showing no major distortion of taste in group A. Anorectic girls generally discarded the sweetest fruit and the fattest meats, but sometimes chose to eat high-calorie food, possibly because of its supposed nutritional value. Their dislike for so-called "light" products was also apparent. Moreover, no regressive tendency to childish choices was found in their eating habits. It is concluded that group A displayed a narrowed food field, but without distortions of taste.

Diverging evolution of anti-GAD and anti-IA-2 antibodies in long-standing diabetes mellitus as a function of age at onset: no association with complications.

Glutamic acid decarboxylase autoantibodies (GAD-A) and tyrosine phosphatase IA-2 autoantibodies (IA2-A) were measured in sera of 50 recently diagnosed (<6 wk, 33% younger than 15 yr), 19 short-term (1 to 9 yr, 35% with onset age below 15 yr) and 89 long-standing diabetic patients (>10 yr, 57% with onset age below 15 yr). Complications were assessed by clinical examination, retinal angiographs and microalbuminuria measurement. Both prevalences and levels of GAD-A and IA2-A decreased with increasing duration of diabetes. However even in those with long duration diabetes, 15 to 63% of the sera were still positive for one or two antibodies. In the group with onset after the age of 15 yr, significantly higher prevalences and levels of GAD-A (but not IA2-A) was observed in comparison with the group with earlier onset. No association was found with any microvascular complications in any group. We conclude that GAD-A and IA2-A persist in some diabetic patients, despite a long duration. Persistence of GAD-A was greatest in those with postpubertal disease onset. We speculate that persistence of some beta-cells or specific environmental factors can sustain one autoimmune reaction especially in some postpubertal-onset diabetic patients.

Pseudohypertriglyceridaemia.

A mistake can be made in interpreting plasma triglyceride levels since in some cases pseudohypertriglyceridaemia may result from increased plasma glycerol due to a glycerol kinase deficit. Most automated triglyceride assays used in laboratories do not contain a negative control, i.e. a glycerol assay. We report two cases with pseudohypertriglyceridaemia due to hyperglycerolaemia and describe the clinical and biological features which suggested the diagnosis.

Different TH2-TH1 balance in V beta 8 and V beta 6 subsets of splenocytes in NOD females in the early phase of diabetogenesis.

Non-obese diabetic (NOD) mice spontaneously develop T-cell-mediated autoimmune diabetes. Initial work on the diabetogenic T-cell repertoire indicated that autoreactive T lymphocytes were polyclonal but that the presence of specific subsets (V beta 8 or V beta 6) might be required for induction of the disease. Further functional analysis of NOD mice T lymphocytes was limited because of the relative anergic state of these cells due to abnormal patterns of cytokine secretion. The purpose of the present study was to establish experimental conditions allowing the exploration of the functional features of minor T-lymphocyte subsets in vitro using low doses of cofactors. The ability of splenocytes to proliferate, respond to, or secrete interleukin-2 and interleukin-4 was explored in young, pre-diabetic or old non-diabetic female NOD mice. No significant bias in T-cell receptor usage was noted in the spleen of these animals, whereas V beta 6 + lymphocytes could be very efficiently stimulated by interleukin-4 and also produce low but detectable amounts of interleukin-4 during the pre-diabetic period in female NOD mice. These results suggest that diabetes induction is preceded by V beta + subset-specific functional changes in the ability of various T cells to respond to or secrete interleukin-2 and interleukin-4, indicating a functional imbalance of the T-cell repertoire expanded by the autoimmune process.

Insulin-induced lipoatrophy in type I diabetes. A possible tumor necrosis factor-alpha-mediated dedifferentiation of adipocytes.

OBJECTIVE: To test the hypothesis that tumor necrosis factor (TNF)-alpha may mediate the loss and the dedifferentiation of subcutaneous fat tissue in the insulin-induced lipoatrophies of a diabetic patient who presented extensive lesions. RESEARCH DESIGN AND METHODS: An in vitro exploration of cytokine production by peripheral blood mononuclear cells (PBMC) from the reported case was performed and compared with the same explorations of PBMC from three nondiabetic subjects and three diabetic patients without lipoatrophic lesions. A proliferation test and an evaluation of TNF-alpha and interleukin (IL)-6 production from PBMC in presence of insulin were studied. RESULTS: The production of TNF-alpha and IL-6 by the macrophages of the patient in presence of insulin were dramatically increased in comparison with control subjects. This process needed cooperation with other lymphoid cells and was abrogated by dexamethasone. CONCLUSIONS: In our reported case, a local hyperproduction of TNF-alpha from macrophages that was induced by the injected insulin could explain the dedifferentiation of the adipocytes of the subcutaneous tissue and the reversion that was induced by the local injection of dexamethasone.

[Corticotropic adenoma in slow adrenal insufficiency]. / Adénome corticotrope au cours d'une insuffisance surrénale lente.

This case report deals with an insulin-dependent diabetic patient suffering peripheral adrenal insufficiency who, after 12 years of substitutive treatment exhibited resistance to mineralo- and gluco-corticoids with relapse of melanodermia and plasma ACTH levels higher than 1500 pg/ml despite increasing doses. A corticotrop macroadenoma was diagnosed by MR imaging and functional tests and confirmed by surgical excision followed by disappearance of resistance. Pre-operative functional investigation show autonomisation of the adenoma but with some partial persisting regulation. This case report draws attention to this rare either complication or association which can occur in peripheral adrenal insufficiency.

Dietary protection against diabetes in NOD mice: lack of a major change in the immune system.

Pregestimil, a hypoallergenic infant formula in which casein hydrolysate replaces protein, protects NOD mice against diabetes, a T-cell-mediated autoimmune disease. Female and cyclosphosphamide (Cy)-treated male NOD mice were used to assess whether a modification of cellular immune mechanisms occurred when animals were fed Pregestimil from weaning to 110 days of life. Insulitis, sialitis and thyroiditis were observed, and the splenic T-cell proliferative response was measured. The ability of splenic T-cells of NOD mice in the Pregestimil group to transfer diabetes adoptively to young irradiated male NOD mice was also assessed. Pregestimil protected female NOD mice against spontaneous diabetes and male NOD mice against acute Cy-induced diabetes. Addition of bovine serum albumin (10%) to the diet did not alter the preventive effect. The Pregestimil diet also lessened insulitis severity in Cy-treated males, though not in females. Sialitis and thyroiditis, observed mainly in females, were not modified by the diets. The TCR-mediated proliferative response of splenocytes tended to increase specifically in Pregestimil-fed and Cy-treated males. Sensitivity to IL-2 was improved. In females, the TCR-mediated proliferative response and the ability of T cells to transfer diabetes adoptively were unchanged. It is concluded that the protective effect of Pregestimil against diabetes in NOD mice cannot be explained by major changes in peripheral immune response.