Heterogeneity of glycaemic phenotypes in type 1 diabetes

AIMS/HYPOTHESIS

Our study aims to uncover glycaemic phenotype heterogeneity in type 1 diabetes.

METHODS

In the Study of the French-speaking Society of Type 1 Diabetes (SFDT1), we characterised glycaemic heterogeneity thanks to a set of complementary metrics: HbA1c, time in range (TIR), time below range (TBR), CV, Gold score and glycaemia risk index (GRI). Applying the Discriminative Dimensionality Reduction with Trees (DDRTree) algorithm, we created a phenotypic tree, i.e. a 2D visual mapping. We also carried out a clustering analysis for comparison.

RESULTS

We included 618 participants with type 1 diabetes (52.9% men, mean age 40.6 years [SD 14.1]). Our phenotypic tree identified seven glycaemic phenotypes. The 2D phenotypic tree comprised a main branch in the proximal region and glycaemic phenotypes in the distal areas. Dimension 1, the horizontal dimension, was positively associated with GRI (coefficient [95% CI]) (0.54 [0.52, 0.57]), HbA1c (0.39 [0.35, 0.42]), CV (0.24 [0.19, 0.28]) and TBR (0.11 [0.06, 0.15]), and negatively with TIR (-0.52 [-0.54, -0.49]). The vertical dimension was positively associated with TBR (0.41 [0.38, 0.44]), CV (0.40 [0.37, 0.43]), TIR (0.16 [0.12, 0.20]), Gold score (0.10 [0.06, 0.15]) and GRI (0.06 [0.02, 0.11]), and negatively with HbA1c (-0.21 [-0.25, -0.17]). Notably, socioeconomic factors, cardiovascular risk indicators, retinopathy and treatment strategy were significant determinants of glycaemic phenotype diversity. The phenotypic tree enabled more granularity than traditional clustering in revealing clinically relevant subgroups of people with type 1 diabetes.

CONCLUSIONS/INTERPRETATION

Our study advances the current understanding of the complex glycaemic profile in people with type 1 diabetes and suggests that strategies based on isolated glycaemic metrics might not capture the complexity of the glycaemic phenotypes in real life. Relying on these phenotypes could improve patient stratification in type 1 diabetes care and personalise disease management.

Coxsackievirus infection induces direct pancreatic β cell killing but poor antiviral CD8+ T cell responses

Coxsackievirus B (CVB) infection of pancreatic β cells is associated with β cell autoimmunity and type 1 diabetes. We investigated how CVB affects human β cells and anti-CVB T cell responses. β cells were efficiently infected by CVB in vitro, down-regulated human leukocyte antigen (HLA) class I, and presented few, selected HLA-bound viral peptides. Circulating CD8+ T cells from CVB-seropositive individuals recognized a fraction of these peptides; only another subfraction was targeted by effector/memory T cells that expressed exhaustion marker PD-1. T cells recognizing a CVB epitope cross-reacted with β cell antigen GAD. Infected β cells, which formed filopodia to propagate infection, were more efficiently killed by CVB than by CVB-reactive T cells. Our in vitro and ex vivo data highlight limited CD8+ T cell responses to CVB, supporting the rationale for CVB vaccination trials for type 1 diabetes prevention. CD8+ T cells recognizing structural and nonstructural CVB epitopes provide biomarkers to differentially follow response to infection and vaccination.

Coxsackievirus infection induces direct pancreatic β-cell killing but poor anti-viral CD8+ T-cell responses

Coxsackievirus B (CVB) infection of pancreatic β cells is associated with β-cell autoimmunity. We investigated how CVB impacts human β cells and anti-CVB T-cell responses. β cells were efficiently infected by CVB in vitro, downregulated HLA Class I and presented few, selected HLA-bound viral peptides. Circulating CD8+ T cells from CVB-seropositive individuals recognized only a fraction of these peptides, and only another sub-fraction was targeted by effector/memory T cells that expressed the exhaustion marker PD-1. T cells recognizing a CVB epitope cross-reacted with the β-cell antigen GAD. Infected β cells, which formed filopodia to propagate infection, were more efficiently killed by CVB than by CVB-reactive T cells. Thus, our in-vitro and ex-vivo data highlight limited T-cell responses to CVB, supporting the rationale for CVB vaccination trials for type 1 diabetes prevention. CD8+ T cells recognizing structural and non-structural CVB epitopes provide biomarkers to differentially follow response to infection and vaccination.

Hybrid Closed Loop Overcomes the Impact of Missed or Suboptimal Meal Boluses on Glucose Control in Children with Type 1 Diabetes Compared to Sensor-Augmented Pump Therapy

Background: It is unclear whether hybrid closed-loop (HCL) therapy attenuates the metabolic impact of missed or suboptimal meal insulin bolus compared with sensor-augmented pump (SAP) therapy in children with type 1 diabetes in free-living conditions. Methods: This is an ancillary study from a multicenter randomized controlled trial that compared 24/7 HCL with evening and night (E/N) HCL for 36 weeks in children between 6 and 12 years old. In the present study, the 60 children from the E/N arm underwent a SAP phase, an E/N HCL for 18 weeks, then a 24/7 phase for 18 weeks, extended for 36 more weeks. The last 28-30 days of each of the four phases were analyzed according to meal bolus management (cumulated 6817 days). The primary endpoint was the percentage of time that the sensor glucose was in the target range (TIR, 70-180 mg/dL) according to the number of missed boluses per day. Findings: TIR was 54% ± 10% with SAP, 63% ± 7% with E/N HCL, and steadily 67% ± 7% with 24/7 HCL. From the SAP phase to 72 weeks of HCL, the percentage of days with at least one missed meal bolus increased from 12% to 22%. Estimated marginal (EM) mean TIR when no bolus was missed was 54% (95% confidence intervals [CI] 53-56) in SAP and it was 13% higher (95% CI 11-15) in the 24/7 HCL phase. EM mean TIR with 1 and ≥2 missed boluses/day was 49.5% (95% CI 46-52) and 45% (95% CI 39-51) in SAP, and it was 15% (95% CI 14-16) and 17% higher (95% CI 6-28), respectively, in the 24/7 HCL phase (P < 0.05 for all comparisons vs. SAP). Interpretation: HCL persistently improves glycemic control compared with SAP, even in case of meal bolus omission. ClinicalTrials.gov (NCT03739099).

Once-Weekly Dulaglutide for the Treatment of Youths with Type 2 Diabetes

BACKGROUND

The incidence of type 2 diabetes mellitus is increasing among youths. Once-weekly treatment with dulaglutide, a glucagon-like peptide-1 receptor agonist, may have efficacy with regard to glycemic control in youths with type 2 diabetes.

METHODS

In a double-blind, placebo-controlled, 26-week trial, we randomly assigned participants (10 to <18 years of age; body-mass index [BMI], >85th percentile) being treated with lifestyle modifications alone or with metformin, with or without basal insulin, in a 1:1:1 ratio to receive once-weekly subcutaneous injections of placebo, dulaglutide at a dose of 0.75 mg, or dulaglutide at a dose of 1.5 mg. Participants were then included in a 26-week open-label extension study in which those who had received placebo began receiving dulaglutide at a weekly dose of 0.75 mg. The primary end point was the change from baseline in the glycated hemoglobin level at 26 weeks. Secondary end points included a glycated hemoglobin level of less than 7.0% and changes from baseline in the fasting glucose concentration and BMI. Safety was also assessed.

RESULTS

A total of 154 participants underwent randomization. At 26 weeks, the mean glycated hemoglobin level had increased in the placebo group (0.6 percentage points) and had decreased in the dulaglutide groups (-0.6 percentage points in the 0.75-mg group and -0.9 percentage points in the 1.5-mg group, P<0.001 for both comparisons vs. placebo). At 26 weeks, a higher percentage of participants in the pooled dulaglutide groups than in the placebo group had a glycated hemoglobin level of less than 7.0% (51% vs. 14%, P<0.001). The fasting glucose concentration increased in the placebo group (17.1 mg per deciliter) and decreased in the pooled dulaglutide groups (-18.9 mg per deciliter, P<0.001), and there were no between-group differences in the change in BMI. The incidence of gastrointestinal adverse events was higher with dulaglutide therapy than with placebo. The safety profile of dulaglutide was consistent with that reported in adults.

CONCLUSIONS

Treatment with dulaglutide at a once-weekly dose of 0.75 mg or 1.5 mg was superior to placebo in improving glycemic control through 26 weeks among youths with type 2 diabetes who were being treated with or without metformin or basal insulin, without an effect on BMI. (Funded by Eli Lilly; AWARD-PEDS ClinicalTrials.gov number, NCT02963766.).

Therapeutic indications and metabolic effects of metreleptin in patients with lipodystrophy syndromes: Real-life experience from a national reference network

AIM

To describe baseline characteristics and follow-up data in patients with lipodystrophy syndromes treated with metreleptin in a national reference network, in a real-life setting.

PATIENTS AND METHODS

Clinical and metabolic data from patients receiving metreleptin in France were retrospectively collected, at baseline, at 1 year and at the latest follow-up during treatment.

RESULTS

Forty-seven patients with lipodystrophy including generalized lipodystrophy (GLD; n = 28) and partial lipodystrophy (PLD; n = 19) received metreleptin over the last decade. At baseline, the median (interquartile range [IQR]) patient age was 29.3 (16.6-47.6) years, body mass index was 23.8 (21.2-25.7) kg/m² and serum leptin was 3.2 (1.0-4.9) ng/mL, 94% of patients had diabetes (66% insulin-treated), 53% had hypertension and 87% had dyslipidaemia. Metreleptin therapy, administered for a median (IQR) of 31.7 (14.2-76.0) months, was ongoing in 77% of patients at the latest follow-up. In patients with GLD, glycated haemoglobin (HbA1c) and fasting triglyceride levels significantly decreased from baseline to 1 year of metreleptin treatment, from 8.4 (6.5-9.9)% [68 (48-85) mmol/mol] to 6.8 (5.6-7.4)% [51(38-57) mmol/mol], and 3.6 (1.7-8.5) mmol/L to 2.2 (1.1-3.7) mmol/L, respectively (P < 0.001), with sustained efficacy thereafter. In patients with PLD, HbA1c was not significantly modified (7.7 [7.1-9.1]% [61 (54-76) mmol/mol] at baseline vs. 7.7 [7.4-9.5]% [61(57-80) mmol/mol] at 1 year), and the decrease in fasting triglycerides (from 3.3 [1.9-9.9] mmol/L to 2.5 [1.6-5.3] mmol/L; P < 0.01) was not confirmed at the latest assessment (5.2 [2.2-11.3] mmol/L). However, among PLD patients, at 1 year, 61% were responders regarding glucose homeostasis, with lower baseline leptin levels compared to nonresponders, and 61% were responders regarding triglyceridaemia. Liver enzymes significantly decreased only in the GLD group.

CONCLUSIONS

In this real-life setting study, metabolic outcomes are improved by metreleptin therapy in patients with GLD. The therapeutic indication for metreleptin needs to be clarified in patients with PLD.

Turner syndrome: French National Diagnosis and Care Protocol (NDCP; National Diagnosis and Care Protocol)

Turner syndrome (TS; ORPHA 881) is a rare condition in which all or part of one X chromosome is absent from some or all cells. It affects approximately one in every 1/2500 liveborn girls. The most frequently observed karyotypes are 45,X (40–50%) and the 45,X/46,XX mosaic karyotype (15–25%). Karyotypes with an X isochromosome (45,X/46,isoXq or 45,X/46,isoXp), a Y chromosome, X ring chromosome or deletions of the X chromosome are less frequent. The objective of the French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins) is to provide health professionals with information about the optimal management and care for patients, based on a critical literature review and multidisciplinary expert consensus. The PNDS, written by members of the French National Reference Center for Rare Growth and Developmental Endocrine disorders, is available from the French Health Authority website. Turner Syndrome is associated with several phenotypic conditions and a higher risk of comorbidity. The most frequently reported features are growth retardation with short adult stature and gonadal dysgenesis. TS may be associated with various congenital (heart and kidney) or acquired diseases (autoimmune thyroid disease, celiac disease, hearing loss, overweight/obesity, glucose intolerance/type 2 diabetes, dyslipidemia, cardiovascular complications and liver dysfunction). Most of the clinical traits of TS are due to the haploinsufficiency of various genes on the X chromosome, particularly those in the pseudoautosomal regions (PAR 1 and PAR 2), which normally escape the physiological process of X inactivation, although other regions may also be implicated. The management of patients with TS requires collaboration between several healthcare providers. The attending physician, in collaboration with the national care network, will ensure that the patient receives optimal care through regular follow-up and screening. The various elements of this PNDS are designed to provide such support.

Dunnigan lipodystrophy syndrome: French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins)

Dunnigan syndrome, or Familial Partial Lipodystrophy type 2 (FPLD2; ORPHA 2348), is a rare autosomal dominant disorder due to pathogenic variants of the LMNA gene. The objective of the French National Diagnosis and Care Protocol (PNDS; Protocole National de Diagnostic et de Soins), is to provide health professionals with a guide to optimal management and care of patients with FPLD2, based on a critical literature review and multidisciplinary expert consensus. The PNDS, written by members of the French National Reference Center for Rare Diseases of Insulin Secretion and Insulin Sensitivity (PRISIS), is available on the French Health Authority website (in French). Dunnigan syndrome is characterized by a partial atrophy of the subcutaneous adipose tissue and by an insulin resistance syndrome, associated with a risk of metabolic, cardiovascular and muscular complications. Its prevalence, assessed at 1/100.000 in Europe, is probably considerably underestimated. Thorough clinical examination is key to diagnosis. Biochemical testing frequently shows hyperinsulinemia, abnormal glucose tolerance and hypertriglyceridemia. Elevated hepatic transaminases (hepatic steatosis) and creatine phosphokinase, and hyperandrogenism in women, are common. Molecular analysis of the LMNA gene confirms diagnosis and allows for family investigations. Regular screening and multidisciplinary monitoring of the associated complications are necessary. Diabetes frequently develops from puberty onwards. Hypertriglyceridemia may lead to acute pancreatitis. Early atherosclerosis and cardiomyopathy should be monitored. In women, polycystic ovary syndrome is common. Overall, the management of patients with Dunnigan syndrome requires the collaboration of several health care providers. The attending physician, in conjunction with the national care network, will ensure that the patient receives optimal care through regular follow-up and screening. The various elements of this PNDS are described to provide such a support.

Management of severe inaugural diabetic ketoacidosis in paediatric intensive care: retrospective comparison of two protocols

The best protocol for severe inaugural diabetic ketoacidosis (DKA) in children remains unclear. We compared two protocols by assessing effects during the first 24 h on osmolality, serum sodium, and glucose variations, which are associated with the risk of cerebral oedema, the most dreaded complication of DKA. We also recorded complications. We retrospectively included children aged 28 days to 18 years and admitted for severe DKA to either of two paediatric intensive care units (PICUs) in Paris (France). The two protocols differed regarding hydration volume, glucose intake, and sodium intake. From 17 June 2010 to 17 June 2015, 93 patients were included, 29 at one PICU, and 64 at the other. We compared severe glycaemic drops (> 5.5 mmol/L/h), mean glycaemia variations, serum sodium, serum osmolality, and the occurrence of cerebral oedema (CE) during the first 24 h after PICU admission. Severe glycaemic drops occurred in 70% of patients, with no between-group difference. Blood glucose, serum sodium, and serum osmolality variations were comparable. Seven (7.5%) patients were treated for suspected CE, (4 [10.3%)] and 3 [6.3%]) in each PICU; none had major residual impairments.

CONCLUSION

 The two paediatric DKA-management protocols differing in terms of fluid-volume, glucose, and sodium intakes had comparable effects on clinical and laboratory-test changes within 24 h. Major drops in glycaemia and osmolality were common with both protocols. No patients had residual neurological impairments.

WHAT IS KNOWN

• Cerebral oedema is the most severe complication of diabteic ketoacidosis in children.The risk of cerebral oedema is dependant on both patient related and treatment-related factors. • The optimal protocol for managing severe inaugural diabetic ketoacidosis in children remains unclear, and few studies have targeted this specific population.

WHAT IS NEW

• Two management protocols that complied with ISPAD guidelines but differed regarding the amounts of fluids, glucose, and sodium administered produced similar outcomes in children with severe inaugural diabetic ketoacidosis. • Cerebral oedema was rare with both protocols and caused no lasting impairments.

Outcomes of hybrid closed-loop insulin delivery activated 24/7 versus evening and night in free-living prepubertal children with type 1 diabetes: A multicentre, randomized clinical trial

AIM

To assess the safety and efficacy of hybrid closed-loop (HCL) insulin delivery 24/7 versus only evening and night (E/N), and on extended 24/7 use, in free-living children with type 1 diabetes.

MATERIALS AND METHODS

Prepubertal children (n = 122; 49 females/73 males; age, 8.6 ± 1.6 years; diabetes duration, 5.2 ± 2.3 years; insulin pump use, 4.6 ± 2.5 years; HbA1c 7.7% ± 0.7%/61 ± 5 mmol/mol) from four centres were randomized for 24/7 versus E/N activation of the Tandem Control-IQ system for 18 weeks. Afterwards, all children used the activated system 24/7 for 18 more weeks. The primary outcome was the percentage of time spent in the 70-180 mg/dL glucose range (TIR).

RESULTS

HCL was active 94.1% and 51.1% of the time in the 24/7 and E/N modes, respectively. TIR from baseline increased more in the 24/7 versus the E/N mode (52.9% ± 9.5% to 67.3% ± 5.6% [+14.4%, 95% CI 12.4%-16.7%] vs. 55.1% ± 10.8% to 64.7% ± 7.0% [+9.6%, 95% CI 7.4%-11.6%]; P = .001). Mean percentage time below range was similarly reduced, from 4.2% and 4.6% to 2.7%, and the mean percentage time above range decreased more in the 24/7 mode (41.9% to 30.0% [-11.9%, 95% CI 9.7%-14.6%] vs. 39.8% to 32.6% [-7.2%, 95% CI 5.0%-9.9%]; P = .007). TIR increased through the whole range of baseline levels and always more with 24/7 use. The results were maintained during the extension phase in those initially on 24/7 use and improved in those with initial E/N use up to those with 24/7 use. Neither ketoacidosis nor severe hypoglycaemia occurred.

CONCLUSIONS

The current study shows the safety and efficacy of the Tandem Control-IQ system in free-living children with type 1 diabetes for both E/N and 24/7 use; 24/7 use shows better outcomes, sustained for up to 36 weeks with no safety issues.

Mitchell-Riley Syndrome: Improving Clinical Outcomes and Searching for Functional Impact of RFX-6 Mutations

AIMS/HYPOTHESIS

Caused by biallelic mutations of the gene encoding the transcription factor RFX6, the rare Mitchell-Riley syndrome (MRS) comprises neonatal diabetes, pancreatic hypoplasia, gallbladder agenesis or hypoplasia, duodenal atresia, and severe chronic diarrhea. So far, sixteen cases have been reported, all with a poor prognosis. This study discusses the multidisciplinary intensive clinical management of 4 new cases of MRS that survived over the first 2 years of life. Moreover, it demonstrates how the mutations impair the RFX6 function.

METHODS

Clinical records were analyzed and described in detail. The functional impact of two RFX6^R181W and RFX6^V506G variants was assessed by measuring their ability to transactivate insulin transcription and genes that encode the L-type calcium channels required for normal pancreatic beta-cell function.

RESULTS

All four patients were small for gestational age (SGA) and prenatally diagnosed with duodenal atresia. They presented with neonatal diabetes early in life and were treated with intravenous insulin therapy before switching to subcutaneous insulin pump therapy. All patients faced recurrent hypoglycemic episodes, exacerbated when parenteral nutrition (PN) was disconnected. A sensor-augmented insulin pump therapy with a predictive low-glucose suspension system was installed with good results. One patient had a homozygous c.1517T>G (p.Val506Gly) mutation, two patients had a homozygous p.Arg181Trp mutation, and one patient presented with new compound heterozygosity. The RFX6^V506G and RFX6^R181W mutations failed to transactivate the expression of insulin and genes that encode L-type calcium channel subunits required for normal pancreatic beta-cell function.

CONCLUSIONS/INTERPRETATION

Multidisciplinary and intensive disease management improved the clinical outcomes in four patients with MRS, including adjustment of parenteral/oral nutrition progression and advanced diabetes technologies. A better understanding of RFX6 function, in both intestine and pancreas cells, may break ground in new therapies, particularly regarding the use of drugs that modulate the enteroendocrine system.

Design of a prospective, longitudinal cohort of people living with type 1 diabetes exploring factors associated with the residual cardiovascular risk and other diabetes-related complications: The SFDT1 study

Type 1 diabetes mellitus (T1DM) is associated with a high risk of cardiovascular (CV) complications, even after controlling for traditional CV risk factors. Therefore, determinants of the residual increased CV morbidity and mortality remain to be discovered. This prospective cohort of people living with T1DM in France (SFDT1) will include adults and children aged over six years living with T1DM, recruited throughout metropolitan France and overseas French departments and territories. The primary objective is to better understand the parameters associated with CV complications in T1DM. Clinical data and biobank samples will be collected during routine visits every three years. Data from connected tools, including continuous glucose monitoring, will be available during the 10-year active follow-up. Patient-reported outcomes, psychological and socioeconomic information will also be collected either at visits or through web questionnaires accessible via the internet. Additionally, access to the national health data system (Health Data Hub) will provide information on healthcare and a passive 20-year medico-administrative follow-up. Using Health Data Hub, SFDT1 participants will be compared to non-diabetic individuals matched on age, gender, and residency area. The cohort is sponsored by the French-speaking Foundation for Diabetes Research (FFRD) and aims to include 15,000 participants.

Molecular and Cellular Bases of Lipodystrophy Syndromes

Lipodystrophy syndromes are rare diseases originating from a generalized or partial loss of adipose tissue. Adipose tissue dysfunction results from heterogeneous genetic or acquired causes, but leads to similar metabolic complications with insulin resistance, diabetes, hypertriglyceridemia, nonalcoholic fatty liver disease, dysfunctions of the gonadotropic axis and endocrine defects of adipose tissue with leptin and adiponectin deficiency. Diagnosis, based on clinical and metabolic investigations, and on genetic analyses, is of major importance to adapt medical care and genetic counseling. Molecular and cellular bases of these syndromes involve, among others, altered adipocyte differentiation, structure and/or regulation of the adipocyte lipid droplet, and/or premature cellular senescence. Lipodystrophy syndromes frequently present as systemic diseases with multi-tissue involvement. After an update on the main molecular bases and clinical forms of lipodystrophy, we will focus on topics that have recently emerged in the field. We will discuss the links between lipodystrophy and premature ageing and/or immuno-inflammatory aggressions of adipose tissue, as well as the relationships between lipomatosis and lipodystrophy. Finally, the indications of substitutive therapy with metreleptin, an analog of leptin, which is approved in Europe and USA, will be discussed.

Practical implementation of automated closed-loop insulin delivery: A French position statement

Automated closed-loop (CL) insulin therapy has come of age. This major technological advance is expected to significantly improve the quality of care for adults, adolescents and children with type 1 diabetes. To improve access to this innovation for both patients and healthcare professionals (HCPs), and to promote adherence to its requirements in terms of safety, regulations, ethics and practice, the French Diabetes Society (SFD) brought together a French Working Group of experts to discuss the current practical consensus. The result is the present statement describing the indications for CL therapy with emphasis on the idea that treatment expectations must be clearly defined in advance. Specifications for expert care centres in charge of initiating the treatment were also proposed. Great importance was also attached to the crucial place of high-quality training for patients and healthcare professionals. Long-term follow-up should collect not only metabolic and clinical results, but also indicators related to psychosocial and human factors. Overall, this national consensus statement aims to promote the introduction of marketed CL devices into standard clinical practice.

Effects of advanced carbohydrate counting on glucose control and quality of life in children with type 1 diabetes

OBJECTIVE

The effect of advanced carbohydrate counting (ACC) on metabolic and quality of life (QOL) outcomes is uncertain in children with type 1 diabetes. Our aim was to determine whether ACC would improve HbA1c and QOL scores as compared with standard nutrition in this population.

METHODS

We randomized 87 patients using pump and rapid-acting analogs in a 1 year randomized multicenter study (age 9.6 ± 3.5 years, diabetes duration 4.6 ± 2.7 years, HbA1c 7.8 ± 0.5% [62 ± 5 mmol/mol]). The ACC group received CC education and the control group received traditional dietary education. HbA1c was measured every 3 months. At 0 and 1 year, general, diabetes-specific, and diet-related QOL were respectively assessed by the KIDSCREEN and WHO-5 questionnaires, the diabetes-specific module of the DISABKIDS, and the diet restriction items of the DSQOLS.

RESULTS

Mean HbA1c was lower in the ACC than the control group at 3 months (P < .05) and tended to be lower at 6 months (P = .10), 9 months (P = .10), but not at 12 months. The mean of individual average HbA1c during the one-year study period (from M3 to M12) was 7.63 ± 0.43 in the ACC vs 7.85 ± 0.47% in the control group (60 ± 5 vs 62 ± 5 mmol/mol)(P < .05). ACC was associated with significantly higher scores at 1 year on the KIDSCREEN children's psychological scale and the KIDSCREEN parents' physical scale, the DISABKIDS children's treatment scale, and the children's and parents' dietary restriction scales of the DSQOLS (indicating better QOL or lower perceived diet restriction).

CONCLUSIONS

ACC may be associated with small improvements in metabolic control and QOL scores in children.

Diagnostic Challenge in PLIN1-Associated Familial Partial Lipodystrophy

CONTEXT

Heterozygous frameshift variants in PLIN1 encoding perilipin-1, a key protein for lipid droplet formation and triglyceride metabolism, have been implicated in familial partial lipodystrophy type 4 (FPLD4), a rare entity with only six families reported worldwide. The pathogenicity of other PLIN1 null variants identified in patients with diabetes and/or hyperinsulinemia was recently questioned because of the absence of lipodystrophy in these individuals and the elevated frequency of PLIN1 null variants in the general population.

OBJECTIVES

To reevaluate the pathogenicity of PLIN1 frameshift variants owing to new data obtained in the largest series of patients with FPLD4.

METHODS

We performed histological and molecular studies for patients referred to our French National Reference Center for Rare Diseases of Insulin Secretion and Insulin Sensitivity for lipodystrophy and/or insulin resistance and carrying PLIN1 frameshift variants.

RESULTS

We identified two heterozygous PLIN1 frameshift variants segregating with the phenotype in nine patients from four unrelated families. The FPLD4 stereotypical signs included postpubertal partial lipoatrophy of variable severity, muscular hypertrophy, acromegaloid features, polycystic ovary syndrome and/or hirsutism, metabolic complications (e.g., hypertriglyceridemia, liver steatosis, insulin resistance, diabetes), and disorganized subcutaneous fat lobules with fibrosis and macrophage infiltration.

CONCLUSIONS

These data suggest that some FPLD4-associated PLIN1 variants are deleterious. Thus, the evidence for the pathogenicity of each variant ought to be carefully considered before genetic counseling, especially given the importance of an early diagnosis for optimal disease management. Thus, we recommend detailed familial investigation, adipose tissue-focused examination, and follow-up of metabolic evolution.

SUN-037 Diagnosis Challenge in Type 4 Familial Partial Lipodystrophic Syndrome

Introduction: Type 4 familial partial lipodystrophic syndrome (FPLD4) is an autosomal dominant disease due to frameshift variants of PLIN1 gene. This gene encodes perilipin 1, a protein playing a key role in the structure of the adipocyte lipid droplet and in the regulation of lipolysis. Only 6 independent families with FPLD4 have been described. The aim of this work was to identify the major signs of the disease in the largest cohort of FPLD4 patients reported to date. Patients and Methods: Clinical and biological phenotype of 11 new patients with a family history of lipodystrophic syndrome and bearing a frameshift variant of PLIN1 gene, were investigated after written informed consent. Histological examination, and perilipin 1 protein expression analyses by western blot on whole cell extracts were performed on biopsies of adipose tissue in 2 patients. Results: We identified 3 heterozygous frameshift variants of PLIN1, segregating with the disease in 11 patients from 5 independent families. Our team had already described the p.Val398Glyfs*167 variant, and 2 new variants p.Gly362Glyfs*63 and p.Pro403Argfs*164 were identified. In all patients next generation sequencing (NGS) excluded any other molecular defect known to be responsible for lipodystrophy. On the studied adipose tissue samples, the PLIN1 variant leads to an abnormal longer form of perilipin 1 with fat fibrosis. The main signs of FPLD4 associate a partial, but also sometimes generalized lipoatrophy of post-pubertal occurrence and a phenotype of variable severity including muscular hypertrophy, acromegaloid facies, hirsutism, and metabolic complications (hypertriglyceridemia, insulin-resistance, diabetes, liver steatosis). Lipoatrophy might be missing or difficult to identify in men and youth. Leptin level was low or inappropriate to BMI, which was below 30 but not always very low. Conclusion: The clinical phenotype of FPLD4 is quite homogeneous, but the clinical diagnosis requires a careful clinical examination and/or an expert advice. An early genetic diagnosis is recommended to confirm the disease and prevent metabolic complications.

Monogenic forms of lipodystrophic syndromes: diagnosis, detection, and practical management considerations from clinical cases

BACKGROUND

Lipodystrophic syndromes are rare diseases of genetic or acquired origin characterized by partial or generalized lack of body fat. Early detection and diagnosis are crucial to prevent and manage associated metabolic dysfunctions, i.e. insulin resistance, dyslipidemia, fatty liver, and diabetes, and to provide appropriate genetic counseling. By means of several representative case studies, this article illustrates the diagnostic and management challenges of lipodystrophic syndromes.

REVIEW

Berardinelli-Seip congenital lipodystrophy (BSCL) is typically diagnosed at birth, or soon thereafter, with generalized lipoatrophy and hepatomegaly secondary to hepatic steatosis. Physicians must also consider this diagnosis in adults with atypical non-autoimmune diabetes, hypertriglyceridemia, and a lean and muscular phenotype. The BSCL1 subtype due to mutations in the AGPAT2 gene can have an unusual presentation, especially in neonates and infants. Particular attention should be paid to infants presenting failure to thrive who also have hepatomegaly and metabolic derangements. The BSCL2 sub-type due to mutations in the BSCL gene tends to be more severe than BSCL1, and is characterized by greater fat loss, mild intellectual disability, earlier onset of diabetes, and higher incidence of premature death. Effective management from an earlier age may moderate the natural disease course. Partial lipodystrophies may easily be confused with common central obesity and/or metabolic syndrome. In patients with unexplained pancreatitis and hypertriglyceridemia, lipodystrophies such as familial partial lipodystrophy type 2 (FPLD2; Dunnigan type, due to LMNA mutations) should be considered. Oral combined contraceptives, which can reveal the disease by inducing severe hypertriglyceridemia, are contraindicated. Endogenous estrogens may also lead to "unmasking" of the FPLD2 phenotype, which often appears at puberty, and is more severe in females than males.

CONCLUSIONS

Diet and exercise, adapted to age and potential comorbidities, are essential prerequisites for therapeutic management of lipodystrophic syndromes. Metreleptin therapy can be useful to manage lipodystrophy-related metabolic complications.

Correction to: In vitro prediction of stop-codon suppression by intravenous gentamicin in patients with cystic fibrosis: a pilot study

The original article [1] contains errors in Table 1 affecting some of the presented oligonucleotide sequences and readthrough values in Table 1.

Continuous subcutaneous insulin infusion allows tolerance induction and diabetes treatment in a type 1 diabetic child with insulin allergy

AIM

Insulin allergy is a rare but serious and challenging condition in patients with type 1 diabetes (T1D). This is a case report of an 8-year-old boy with T1D and an allergy to insulin.

CASE REPORT

Three months after being diagnosed with T1D, the patient developed progressive skin reactions to insulin, characterized by small 1.5-cm pruritic wheals at injection sites that persisted for several days. Seven months after diagnosis, he experienced two episodes of generalized urticaria with systemic symptoms that were seen within a few seconds of insulin injection. Examination revealed lipoatrophy of the thighs. Intradermal skin tests were positive for protamine, glargine and lispro. The patient was started on a continuous subcutaneous insulin infusion (CSII) tolerance induction protocol, consisting of a very low basal rate that was progressively increased, with the first bolus given under medical supervision, and was well tolerated for 4 months. After this period of time, the skin wheals reappeared, localized to the infusion sites, but without urticaria or any other generalized reactions. Intradermal skin tests were repeated and were again positive. Serum insulin-specific IgE measured 30 months after the first allergic reactions were positive. After 3 years, pump therapy is ongoing and blood glucose control has remained relatively good (HbA1c 7.6%).

CONCLUSION

In T1D children with insulin allergy, CSII can successfully be used to both induce insulin tolerance and allow diabetes insulin therapy, although insulin desensitization cannot always be fully achieved. The induction protocol was easily manageable partly due to the "honeymoon" period that the patient was still in, but it should nonetheless be used even when the patient has higher insulin requirements.

Moderate deterioration in glucose tolerance during high-dose growth hormone therapy in glucocorticoid-treated patients with juvenile idiopathic arthritis

OBJECTIVES

To describe glucose metabolism changes during growth hormone (GH) treatment in juvenile idiopathic arthritis (JIA).

STUDY DESIGN

Observational study in 58 children on glucocorticoid therapy (GC) for JIA, of whom 28 received late GH therapy (7.3 +/- 3.4 years into GC), 15 early GH therapy (1.2 +/- 0.1 years into GC), and 15 no GH therapy. The GH dose was 0.46 mg/kg/week. Oral glucose tolerance testing with insulin and glycosylated hemoglobin assays were performed yearly. Nonparametric tests were used to compare groups after 3 years and regression analyses to estimate factors predicting glucose AUC and HOMA-IR at baseline and after 3 years.

RESULTS

GH combined with GC was associated with an increase in mean fasting insulinemia. Late GH therapy patients exhibited significant increases over time in mean fasting glycemia (p = 0.01), mean 2-hour postglucose load glycemia (p < 0.05), mean AUC for glucose (p < 0.05), and mean HOMA-IR (p < 0.05). Impaired glucose tolerance was found in 16/43 GH-treated patients (37%) and transient diabetes in 2 (5%) patients.

CONCLUSIONS

GH treatment in JIA children decreased insulin sensitivity but had only modest effects on glucose tolerance. Close monitoring by oral glucose tolerance testing is crucial before and during GH treatment, particularly during puberty and relapses.

Can we prevent diabetic ketoacidosis in children?

Diabetic ketoacidosis (DKA) is an acute potentially life-threatening complication of diabetes affecting more than 100,000 persons annually in the United States. Although major advances have improved diabetes care, DKA remains the leading cause of hospitalization, morbidity, and death in youth with type 1 diabetes (T1D). As the majority of patients presenting with DKA have established diabetes, it is important to address outpatient educational approaches directed at sick-day management and early identification and treatment of impending DKA. Teaching and reinforcement of sick-day rules involves improved self-care with consistent self-monitoring of blood glucose and ketones, and timely administration of supplemental insulin and fluids. DKA as an initial manifestation of T1D may be less amendable to prevention except with an increased awareness by the lay and medical communities of the symptoms of diabetes and surveillance in high-risk populations potentially identified by family history or genetic susceptibility. New technologies that can detect the blood ketone 3beta-hydroxybutyrate (3beta-OHB) instead of traditional urine ketones appears to provide opportunity for early identification and treatment of impending DKA leading to reduced need for hospitalization and potential cost-savings.

In vitro prediction of stop-codon suppression by intravenous gentamicin in patients with cystic fibrosis: a pilot study

BACKGROUND

Cystic fibrosis (CF) is caused by mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein, which acts as a chloride channel activated by cyclic AMP (cAMP). The most frequent mutation found in 70% of CF patients is F508del, while premature stop mutations are found in about 10% of patients. In vitro aminoglycoside antibiotics (e.g. gentamicin) suppress nonsense mutations located in CFTR permitting translation to continue to the natural termination codon. Pharmacologic suppression of stop mutations within the CFTR may be of benefit to a significant number of patients. Our pilot study was conducted to determine whether intravenous gentamicin suppresses stop codons in CF patients and whether it has clinical benefits.

METHODS

A dual gene reporter system was used to determine the gentamicin-induced readthrough level of the most frequent stop mutations within the CFTR in the French population. We investigated readthrough efficiency in response to 10 mg/kg once-daily intravenous gentamicin perfusions in patients with and without stop mutations. Respiratory function, sweat chloride concentration, nasal potential difference (NPD) and CFTR expression in nasal epithelial cells were measured at baseline and after 15 days of treatment.

RESULTS

After in vitro gentamicin incubation, the readthrough efficiency for the Y122X mutation was at least five times higher than that for G542X, R1162X, and W1282X. In six of the nine patients with the Y122X mutation, CFTR immunodetection showed protein at the membrane of the nasal epithelial cells and the CFTR-dependent Cl- secretion in NPD measurements increased significantly. Respiratory status also improved in these patients, irrespective of the gentamicin sensitivity of the bacteria present in the sputum. Mean sweat chloride concentration decreased significantly and normalised in two patients. Clinical status, NPD and sweat Cl- values did not change in the Y122X patients with no protein expression, in patients with the other stop mutations investigated in vitro and those without stop mutations.

CONCLUSION

Suppression of stop mutations in the CFTR gene with parenteral gentamicin can be predicted in vitro and is associated with clinical benefit and significant modification of the CFTR-mediated Cl- transport in nasal and sweat gland epithelium.

The B subunit of Shiga toxin fused to a tumor antigen elicits CTL and targets dendritic cells to allow MHC class I-restricted presentation of peptides derived from exogenous antigens

Immunization with peptide or recombinant proteins generally fails to elicit CTL, which are thought to play a key role in the control of virus-infected cells and tumor growth. In this study we show that the nontoxic B subunit of Shiga toxin fused to a tumor peptide derived from the mouse mastocytoma P815 can induce specific CTL in mice without the use of adjuvant. The Shiga B subunit acts as a vector rather than as an adjuvant, because coinjection of the tumor peptide and the B subunit as separate entities does not lead to CTL induction. We also demonstrated that in vitro the B subunit mediates the delivery of various exogenous CD8 T cell epitopes into the conventional MHC class I-restricted pathway, as this process is inhibited by brefeldin A and lactacystin and requires a functional TAP system. In contrast to other nonviral methods for transport of exogenous Ags into the endogenous MHC class I pathway that involve macropinocytosis or phagocytosis, the Shiga B subunit targets this pathway in a receptor-dependent manner, namely via binding to the glycolipid Gb3. Because this receptor is highly expressed on various dendritic cells, it should allow preferential targeting of the Shiga B subunit to these professional APCs. Therefore, the Shiga B subunit appears to represent an attractive vector for vaccine development due to its ability to target dendritic cells and to induce specific CTL without the need for adjuvant.

Simultaneous expression of NAD-dependent isocitrate dehydrogenase and other krebs cycle genes after nitrate resupply to short-term nitrogen-starved tobacco

Mitochondrial NAD-dependent (IDH) and cytosolic NADP-dependent isocitrate dehydrogenases have been considered as candidates for the production of 2-oxoglutarate required by the glutamine synthetase/glutamate synthase cycle. The increase in IDH transcripts in leaf and root tissues, induced by nitrate or NH4+ resupply to short-term N-starved tobacco (Nicotiana tabacum) plants, suggested that this enzyme could play such a role. The leaf and root steady-state mRNA levels of citrate synthase, acotinase, IDH, and glutamine synthetase were found to respond similarly to nitrate, whereas those for cytosolic NADP-dependent isocitrate dehydrogenase and fumarase responded differently. This apparent coordination occurred only at the mRNA level, since activity and protein levels of certain corresponding enzymes were not altered. Roots and leaves were not affected to the same extent either by N starvation or nitrate addition, the roots showing smaller changes in N metabolite levels. After nitrate resupply, these organs showed different response kinetics with respect to mRNA and N metabolite levels, suggesting that under such conditions nitrate assimilation was preferentially carried out in the roots. The differential effects appeared to reflect the C/N status after N starvation, the response kinetics being associated with the nitrate assimilatory capacity of each organ, signaled either by nitrate status or by metabolite(s) associated with its metabolism.

Mitochondrial localization of a NADP-dependent [corrected] isocitrate dehydrogenase isoenzyme by using the green fluorescent protein as a marker

In this work, we describe the isolation of a new cDNA encoding an NADP-dependent isocitrate dehydrogenase (ICDH). The nucleotide sequence in its 5' region gives a deduced amino acid sequence indicative of a targeting peptide. However, even if this cDNA clearly encodes a noncytosolic ICDH, it is not possible to say from the targeting peptide sequence to which subcellular compartment the protein is addressed. To respond to this question, we have transformed tobacco plants with a construct containing the entire targeting signal-encoding sequence in front of a modified green fluorescent protein (GFP) gene. This construct was placed under the control of the cauliflower mosaic virus 35S promoter, and transgenic tobacco plants were regenerated. At the same time, and as a control, we also have transformed tobacco plants with the same construct but lacking the nucleotide sequence corresponding to the ICDH-targeting peptide, in which the GFP is retained in the cytoplasm. By optical and confocal microscopy of leaf epiderm and Western blot analyses, we show that the putative-targeting sequence encoded by the cDNA addresses the GFP exclusively into the mitochondria of plant cells. Therefore, we conclude that this cDNA encodes a mitochondrial ICDH.

Identification of a tobacco cDNA encoding a cytosolic NADP-isocitrate dehydrogenase

A cDNA which encodes a specific member of the NADP-dependent isocitrate dehydrogenase (ICDH) multi-isoenzyme family has been isolated from a tobacco cell suspension library, and the expression pattern of ICDH transcripts examined in various plant tissues. To assign this cDNA to a specific ICDH isoenzyme, the major, cytosolic ICDH isoenzyme of tobacco leaves (ICDH1) was purified to homogeneity and its N-terminus as well as several tryptic peptides, representing 30% of the protein, were sequenced. The comparison of these amino acid sequences with the deduced protein sequence of the cDNA confirmed that this clone encodes for ICDH1. The total ICDH specific activity and protein content were higher in vascular-enriched tobacco leaf tissue than in deveined (depleted in midrib and first-order veins) leaves. Taking advantage of antibodies raised against either ICDH1 or the chloroplastic ICDH2 isoenzyme from tobacco cell suspensions, an immuno-cytochemical approach indicated that the ICDH1 isoenzyme, located in the cytosolic compartment of tobacco leaf cells, is responsible for this expression pattern. This observation was confirmed by northern blot analyses, using a specific probe obtained from the 3' non-coding region of the ICDH1 cDNA. A comparison of ICDH protein sequences shows a large degree of similarity between eukaryotes (> 60%) but a poor homology is observed when compared to Escherichia coli ICDH (< 20%). However, it was found that the amino acids implicated in substrate binding, deduced from the 3-dimensional structure of the E. coli NADP-ICDH, appear to be conserved in all the deduced eukaryotic ICDH proteins reported until now.

Purification and characterization of a fully active recombinant tobacco cytosolic NADP-dependent isocitrate dehydrogenase in Escherichia coli: evidence for a role for the N-terminal region in enzyme activity

The recently isolated full-length NADP-dependent isocitrate dehydrogenase (ICDH) cDNA encoding the tobacco cytosolic isoenzyme has been cloned into the expression vector pET8c and used to transform Escherichia coli strain BL21 (DE3). The recombinant protein was purified to electrophoretic homogeneity and used to raise polyclonal antibodies. Its kinetic properties were found to be identical to those of the cytosolic ICDH isoenzyme purified from tobacco cell cultures. The recombinant and the endogenous bacterial ICDH could be easily distinguished by their different behaviors during anion-exchange column chromatography and immunological response. An incomplete ICDH-encoding cDNA clone, encoding a protein lacking the first 36 amino acids at the N-terminus, was cloned into the expression vector pKK233-2 and used to transform ICDH-lacking E. coli cells (strain 2004). The truncated, recombinant ICDH produced by the bacteria was found to be inactive.

Monocotyledonous C4 NADP(+)-malate dehydrogenase is efficiently synthesized, targeted to chloroplasts and processed to an active form in transgenic plants of the C3 dicotyledon tobacco

Chloroplastic NADP(+)-malate dehydrogenase (cpMDH, EC 1.1.1.82) is a key enzyme in the carbon-fixation pathway of some C4 plants such as the monocotyledons maize or Sorghum. We have expressed cpMDH from Sorghum vulgare Pers. in transgenic tobacco (Nicotiana tabacum L.) (a dicotyledonous C3 plant) by using a gene composed of the Sorghum cpMDH cDNA under the control of cauliflower mosaic virus 35S promoter. High steady-state levels of cpMDH mRNA were observed in isogenic dihaploid transgenic tobacco lines. Sorghum cpMDH protein was detected in transgenic leaf extracts, where a threefold higher cpMDH activity could be measured, compared with control tobacco leaves. The recombinant protein was identical in molecular mass and in N-terminal sequence to Sorghum cpMDH. The tobacco cpMDH protein which has a distinct N-terminal sequence, could not be detected in transgenic plants. Immunocytochemical analyses showed that Sorghum cpMDH was specifically localized in transgenic tobacco chloroplasts. These data indicate that Sorghum cpMDH preprotein was efficiently synthesized, transported into and processed in tobacco chloroplasts. Thus, C3-C4 photosynthesis specialization or monocotyledon-dicotyledon evolution did not affect the chloroplastic protein-import machinery. The higher levels of cpMDH in transgenic leaves resulted in an increase of L-malate content, suggesting that carbon metabolism was altered by the expression of the Sorghum enzyme.

Purification and Characterization of Chloroplastic NADP-Isocitrate Dehydrogenase from Mixotrophic Tobacco Cells (Comparison with the Cytosolic Isoenzyme)

Green, mixotrophic tobacco (Nicotiana tabacum) cell cultures in the exponential growth phase were found to have two clearly distinguishable NADP-isocitrate dehydrogenase (ICDH; EC 1.1.1.42) isoenzymes. Their elution behavior during anion-exchange column chromatography was similar to that described previously for the cytosolic (ICDH1) and chloroplastic (ICDH2) enzymes from pea (Pisum sativum) leaves. ICDH2 was absent in etiolated tobacco cell suspensions and appeared during the greening process. Both isoforms were purified to apparent electrophoretic homogeneity by ammonium sulfate fractionation and anion-exchange and affinity chromatography. The isoenzymes were separated on a DEAE-Sephacel column, but the most effective step was a Matrex Red-A column, which enabled an overall purification of 833- and 1328-fold for ICDH1 and ICDH2, respectively. Polyclonal antibodies were raised against each isoform. The ICDH2-specific antibody was used to localize tobacco leaf ICDH2 in situ by an immunogold labeling technique. The enzyme was found largely, if not exclusively, in the chloroplasts of green leaves. ICDH1 and ICDH2 were shown to have apparent native molecular weights of 117,000 and 136,000, respectively, and to consist of identical, 48.5-kD subunits. Similar apparent Km values for NADP, D(+)isocitrate, and Mg2+ were found for the two enzymes when assayed with Mg2+ as the metal cofactor.

Demonstration of hepatitis B virus DNA by polymerase chain reaction in the serum and the liver after spontaneous or therapeutically induced HBeAg to anti-HBe or HBsAg to anti-HBs seroconversion in patients with chronic hepatitis B

The objective was to determine the proportion of patients with chronic hepatitis B in whom hepatitis B virus DNA is demonstrated by polymerase chain reaction after HBeAg to anti-HBe or HBsAg to anti-HBs spontaneous or therapeutically induced seroconversion. Polymerase chain reaction was performed on serum 6 and 12 mo after HBeAg to anti-HBe seroconversion in 12 patients and 2, 6 and 12 mo after HBsAg to anti-HBs seroconversion in 13 patients. Polymerase chain reaction was performed on liver tissue after HBeAg to anti-HBe seroconversion in five patients and after HBsAg to anti-HBs seroconversion in one patient. Serum HBV DNA was demonstrated by polymerase chain reaction in 83% of patients 6 or 12 mo after HBeAg to anti-HBe seroconversion and in 58%, 31% and 15% of patients at 2, 6 and 12 mo, respectively, after HBsAg to anti-HBs seroconversion. Liver HBV DNA was demonstrated by polymerase chain reaction in all patients tested. Our results show that (a) a reduced level of hepatitis B virus replication persists in most of the patients after HBeAg to anti-HBe seroconversion and might be predictive of reactivation, and (b) in contrast, hepatitis B virus replication progressively disappears in most of the patients after HBsAg to anti-HBs seroconversion.

Hepatic vein thrombosis in Behçet's disease

We describe four patients with hepatic vein thrombosis caused by Behçet's disease and review the 17 previously published cases. In addition, we compared these 21 cases of hepatic vein thrombosis to our 24 cases of hepatic vein thrombosis caused by primary myeloproliferative disorders. In patients with Behçet's disease, a male predominance (male/female ratio, 19:1) contrasted with the female predominance found in patients with hepatic vein thrombosis complicating primary myeloproliferative disorders (sex ratio = 1:3). The mean age at clinical onset was younger in patients with Behçet's disease than in those with primary myeloproliferative disorders (29 vs. 35 yr). Obstruction of the inferior vena cava was found in 90% of patients with hepatic vein thrombosis caused by Behçet's disease. Inferior vena caval thrombosis appears to be the main pathophysiological mechanism of hepatic vein thrombosis in patients with Behçet's disease. Unlike patients with primary myeloproliferative disorders who often had a progressive course, one third of patients with Behçet's disease had acute liver failure and died within 2 wk of clinical onset. These findings suggest that, in patients with Behçet's disease, hepatic vein thrombosis is a sudden event usually related to the extension of a caval thrombus to the ostium of the hepatic veins.

Hypercalcaemia associated with chronic viral hepatitis

A patient with long lasting non-parathyroid hormone mediated hypercalcaemia occurring within the context of hepatitis B virus chronic hepatitis is reported. Hepatocellular carcinoma and bone malignancy were carefully excluded. The biological pattern associated hypercalcaemia with normal phosphataemia, low nephrogenic cAMP level and high level of tubular reabsorption of phosphate. The usual causes of hypercalcaemia were ruled out. Hypercalcaemia may represent a rare biological feature of some advanced liver disease. The underlying mechanisms remain to be elucidated.

Chromatographic and immunological evidence that chloroplastic and cytosolic pea (Pisum sativum L.) NADP-isocitrate dehydrogenases are distinct isoenzymes

Two NADP-isocitrate dehydrogenase isoenzymes designated as NADP-IDH1 and NADP-IDH2 (EC 1.1.1.42) were identified in pea (Pisum sativum) leaf extracts by diethylaminoethylcellulose chromatography. The predominant form was found to be NADP-IDH1 while NADP-IDH2 represented only about 4% of the total leaf enzyme activity. These enzymes share few common epitopes as NADP-IDH2 was poorly recognized by the specific polyclonal antibodies raised against NADP-IDH1, and as a consequence NADP-IDH2 does not result from a post-translational modification of NADP-IDH1. Subcellular fractionation and isolation of chloroplasts through a Percoll gradient, followed by the identification of the associated enzymes, showed that NADP-IDH1 is restricted to the cytosol and NADP-IDH2 to the chloroplasts. Compared with the cytosolic isoenzyme, NADP-IDH2 was more thermolabile and exhibited a lower optimum pH. The data reported in this paper constitute the first report that the chloroplastic NADP-IDH and the cytosolic NADP-IDH are two distinct isoenzymes. The possible functions of the two isoenzymes are discussed.

Effet de l'ATP et de Mg2+ sur les activités ribulose-diphosphate carboxylase et ribose-5-phosphate isomérase et kinase d'une préparation enzymatique de chloroplastes

CO2 fixation in the presence of Ru-DP or R-5-P, catalyzed by proteins precipitated from isolated chloroplasts, is affected by ATP. The enzymes of the chloroplastic preparation are mainly Ru-DP carboxylase, R-5-P isomerase and Ru-5-P kinase. ATP inhibits the activity of the Ru-DP carboxylase. This is true for the enzyme of the crude protein preparation as well as for the purified enzyme. The inhibition by ATP is overcome by Mg2+. This may be related to the formation of a chelate with ATP and Mg2+, which lowers the level of the Ru-DP carboxylase – Mg2+ – CO2 complex.However, R-5-P kinase activity is enhanced by ATP. As a result of the different responses of the two enzymes to ATP, CO2 fixation coupled to Ru-DP formation from R-5-P, is enhanced by low concentrations of ATP and inhibited by concentrations above 2 mM.