Glucagon gene expression in the endocrine pancreas: the role of the transcription factor Pax6 in α-cell differentiation, glucagon biosynthesis and secretion

The glucagon gene is expressed in α-cells of the pancreas, L cells of the intestine and the hypothalamus. The determinants of the α-cell-specific expression of the glucagon gene are not fully characterized, although Arx, Pax6 and Foxa2 are critical for α-cell differentiation and glucagon gene expression; in addition, the absence of the β-cell-specific transcription factors Pdx1, Pax4 and Nkx6.1 may allow for the glucagon gene to be expressed. Pax6, along with cMaf and MafB, binds to the DNA control element G(1) which confers α-cell specificity to the promoter and to G(3) and potently activates glucagon gene transcription. In addition, to its direct role on the transcription of the glucagon gene, Pax6 controls several transcription factors involved in the activation of the glucagon gene such as cMaf, MafB and NeuroD1/Beta2 as well as different steps of glucagon biosynthesis and secretion. We conclude that Pax6 independently of Arx and Foxa2 is critical for α-cell function by coordinating glucagon gene expression as well as glucagon biosynthesis and secretion.

[Management of gestational diabetes: current knowledge and future perspectives]

Gestational diabetes (GDM) is one of the most common complications of pregnancy and its prevalence is increasing continuously. Diagnosis, screening of GDM and therapeutic interventions are topics of ongoing controversies and uncertainty that have contributed to make the management of GDM complex and different from one country to another. Recent studies, such as ACHOIS and HAPO, have contributed to better define screening criteria and international recommendations and have demonstrated that management of GDM, including glucose monitoring, diet and insulin if needed, is worthwhile. This article summarizes the current status of screening, management of GDM and postpartum follow-up.

[Important of off loading in the treatment of foot diabetic ulcers]

Foot ulcers are a frequent complication and develop in 15% of patient with diabetes. Ulceration is caused by several factor including neuropathy, arterial insufficiency and infection. Neuropathy results in a loss of the protective sensation and foot deformation. Off loading is an important part of the treatment permitting to reduce pressure and improve healing. Total casting is the gold standard and healing is observed in 90%, but there are several contraindications and limitations. Alternatives include removal devices that must be evaluated to improve off-loading and patient observance. Prevention with specific follow-up and shoes adaptation is recommended to prevent recurrent ulcer.

[Glycated hemoglobin: a new screening tool?]

Evaluation of mean glycemic control in diabetic patients is possible with the measure of glycosylated hemoglobin (HbA1c). Recently, new recommendations were made giving this test a diagnostic value for diabetes. HbA1c is the best prediction parameter of complications linked to diabetes; its measure is relatively accurate and simple. Nevertheless, the threshold value is arbitrary and a standardized method of dosage still remains limited. The aim of this article is to analyze the implementation of this dosage, its advantages and disadvantages as a diagnostic tool in comparison with plasma glycaemia, and current data concerning its sensibility, specificity and clinical implication.

Pressure-induced polyamorphism in salty water

We investigated the metastable phase diagram of an ionic salt aqueous solution, LiCl:6D₂O, at high pressure and low temperature by neutron diffraction measurements and computer simulations. We show that the presence of salt triggers a stepwise transformation, under annealing at high pressure, to a new very high-density amorphous form. The transition occurs abruptly at 120 K and 2 GPa, is reversible, and is characterized by a sizeable enthalpy release. Simulations suggest that the polyamorphic transition is linked to a local structural reorganization of water molecules around the Li ions.

[About retention]

The aim of temporary retention is not to eliminate every causes of relapse and to ensure the stability of treatment, but to eliminate one cause of relapse: the periodontal reactions consecutive to the orthodontic displacement of teeth. The other causes of relapse must be eliminated by the treatment itself, and not by retention. To be effective the retention must be immediate, complete and prolonged. The most used temporary retainers are: the Hawley retainer, the vacuum-retainers and the bonded retainers. None of which is perfect. Only the permanent retention can ensure the stability whatever the cause of relapse. The risks of permanent retainers are not yet well known.

Magnetic ordering in solid oxygen up to room temperature

Oxygen is the only elemental molecule which carries an electronic magnetic moment. As a consequence, the different solid phases encountered on cooling show various degrees of magnetic order, and similar behavior is expected under compression. Here we present neutron diffraction data which reveal the magnetic ordering under high pressure in the delta ("orange") phase, i.e., in the range 6-8 GPa and 20-240 K. We show that delta-O2 contains in total three different magnetic structures, all of them being antiferromagnetic and differing in the stacking sequence of O2 sheets along the c axis. This structural diversity can be explained by the quasi-two-dimensional nature of delta-O2 and the strong orientation dependence of the magnetic exchange interaction between O2 molecules. The results show that delta-O2 is a room temperature antiferromagnet.

[The vocation of orthodontics]

For Angle, the goal of orthodontic treatment was to correct malocclusions. Then, the raison d'être seemed to be to restore normality as described through an increasing number of measurements and in seeking an average value. But 95.5% of variations were in fact normal and didn't need to be brought into a normal range. In addition, conforming to average dimensions was not an appealing goal for prospective patients. It is not divergence from the average that justifies treatment; it is instead the disturbances that these divergences engender. What are needed in the future are fewer measurements and more applications of clinical treatment. It is towards this route that the definitions of orthodontics and dento-facial orthopedics adopted by the SFODF direct us.

Portable multi-anvil device for in situ angle-dispersive synchrotron diffraction measurements at high pressure and temperature

A recently developed portable multi-anvil device for in situ angle-dispersive synchrotron diffraction studies at pressures up to 25 GPa and temperatures up to 2000 K is described. The system consists of a 450 ton V7 Paris-Edinburgh press combined with a Stony Brook ;T-cup' multi-anvil stage. Technical developments of the various modifications that were made to the initial device in order to adapt the latter to angular-dispersive X-ray diffraction experiments are fully described, followed by a presentation of some results obtained for various systems, which demonstrate the power of this technique and its potential for crystallographic studies. Such a compact large-volume set-up has a total mass of only 100 kg and can be readily used on most synchrotron radiation facilities. In particular, several advantages of this new set-up compared with conventional multi-anvil cells are discussed. Possibilities of extension of the (P,T) accessible domain and adaptation of this device to other in situ measurements are given.

Long-term insulin-independence after allogeneic islet transplantation for type 1 diabetes: over the 10-year mark

Results of islet of Langerhans transplantation have markedly improved in recent years, but most patients still lose insulin independence in the long-term. We report herein the longest (over 11 years) case of insulin independence after allogeneic islet transplantation. The subject had a 27-year history of type 1 diabetes and received a single islet-after-kidney graft of 8800 islet equivalents (IEQ)/kg, pooled from 2 donors. Insulin was discontinued by 3 months posttransplant and the patient has remained off insulin ever since. Yearly follow-up studies have revealed normal metabolic control, including normal oral glucose tolerance test (OGTT). Reasons for success may involve choice of immunosuppression, low metabolic demand and low immune responsiveness as suggested by an excellent HLA matching and a high count of circulating regulatory T cells. This observation is so far an exceptional case, but clearly demonstrates the validity of the concept that long-term insulin independence after allogeneic islet transplantation is an achievable target.

Treating type 2 diabetes: how safe are current therapeutic agents?

Sulphonylureas (SUs) and biguanides (metformin) are the current mainstays in the treatment of type 2 diabetes (T2DM) and represent the most commonly used oral hypoglycaemic agents (OHAs). In recent years, a variety of new OHAs have become available, including thiazolidinediones, glinides, alpha-glucosidase inhibitors, glucagon-like peptide-1 agonists, amylin analogues and dipeptidyl peptidase-IV inhibitors, providing physicians with a larger therapeutic catalogue than ever before. The traditional drugs metformin and SUs have an established safety profile through long-term use. However, long-term clinical trials and routine use are lacking for many of the new agents, and some potentially serious side effects have been reported with several of these compounds. Until adequate data is obtained, it is difficult to assess the risk-benefit ratio of these agents in relation to the traditional drugs. Until that becomes fully documented, it may be wise to start pharmacologic treatment of patients on an individual basis, weighing the benefits and costs of each medication. Thus, there remains a place for well-established drugs that have a proven safety record and are supported by years of clinical use for the treatment of T2DM.

[Importance of the post-prandial glycemia in the management of type 2 diabetes]

Cardiovascular disease is the main cause of mortality in diabetic patients. The risk of cardiovascular disease occurs at a lower glycemic level compared to microvascular complications. Post-prandial hyperglycemia seems to play a major role in the development of atherosclerotic lesions. In this article we review the evidence regarding the prognostic value of post-challenge hyperglycaemia relative to the risk of cardiovascular disease, explore the physio-pathologic mechanisms responsible for the negative effects of post-prandial hyperglycaemia and detail the benefits of treatment aimed at controlling post-prandial glycaemia.

[Hypoglycemia and diabetes]

Hypoglycaemia represents the limiting factor to obtain good glycemic control. Dysregulation of counteracting mechanisms and autonomic nervous system neuropathy contribute a strong increase in the incidence of hypoglycaemia in type 1 diabetic patients, but also in long lasting type 2 diabetic patients. Hypoglycaemia in elderly poses a diagnostic and clinical challenge of the unsual clinical presentation causing a delay in treatment. Treatment however, is simple and follows early detection of symptoms by the patient and his family. Prevention has a major role and involves identification of individual risk factors for hypoglycaemia and patient's education with the objective of adapting treatment to the usual habits of the patient.