Anti-Müllerian hormone: A function beyond the Müllerian structures.

The anti-Müllerian hormone (AMH) is a heterodimeric glycoprotein belonging to the TGFb superfamily implicated in human embryonic development. This hormone was first described as allowing regression of the epithelial embryonic Müllerian structures in males, which would otherwise differentiate into the uterus and fallopian tubes. It activates a signaling pathway mediated by two transmembrane receptors. Binding of AMH to its receptor induces morphological changes leading to the degeneration of Müllerian ducts. Recently, new data has shown the role played by this hormone on structures other than the genital tract. If testicular AMH expression decreases in humans over the course of a lifetime, synthesis may persist in other tissues in adulthood. The mechanisms underlying its production have been unveiled. The aim of this review is to describe the different pathways in which AMH has been identified and plays a pivotal role.

[Brachytherapy for cutaneous and lip carcinomas]. / Curiethérapie des carcinomes cutanés et de la lèvre.

Cutaneous basal or squamous cell carcinomas are frequent lesions, their prognosis being associated to local control. Surgery remains the standard of treatment, if a complete resection can be realized without impairment of cosmesis or function. Brachytherapy can be used in the other cases, and is especially well adapted to periorificial lesions of the face. It is mostly realized with low dose rate iridium wires, but can be done with high dose rate if outpatient treatment is preferred. It allows high local control rates with very few late complications. The indication has to be discussed as first line treatment, according to the patient's age and general condition, the characteristics of the lesion, and the risk of late cosmetic or functional side-effects of the different therapeutic options.

[Brachytherapy for extremity soft tissue sarcomas]. / Curiethérapie des sarcomes des tissus mous des membres.

The standard of care of local treatment for extremities soft tissue sarcomas relies on conservative surgery combined with external beam radiotherapy. Brachytherapy can be realized instead of external beam radiotherapy in selected cases, or more often used as a boost dose on a limited volume on the area at major risk of relapse, especially if a microscopic positive resection is expected. In these cases, this combination allows to obtain the best local control rates published. Close interaction and communication between radiation oncologist and surgeon are mandatory at the time of implantation to limit the risk of side effects. Long-term results are available for low-dose rate brachytherapy. Nowadays, pulsed dose rate is more often used. More limited experience has been reported for high dose rate.

Peroxisome proliferator-activated receptor alpha (PPARalpha) protects against oleate-induced INS-1E beta cell dysfunction by preserving carbohydrate metabolism.

AIMS/HYPOTHESIS: Pancreatic beta cells chronically exposed to fatty acids may lose specific functions and even undergo apoptosis. Generally, lipotoxicity is triggered by saturated fatty acids, whereas unsaturated fatty acids induce lipodysfunction, the latter being characterised by elevated basal insulin release and impaired glucose responses. The peroxisome proliferator-activated receptor alpha (PPARalpha) has been proposed to play a protective role in this process, although the cellular mechanisms involved are unclear. METHODS: We modulated PPARalpha production in INS-1E beta cells and investigated key metabolic pathways and genes responsible for metabolism-secretion coupling during a culture period of 3 days in the presence of 0.4 mmol/l oleate. RESULTS: In INS-1E cells, the secretory dysfunction primarily induced by oleate was aggravated by silencing of PPARalpha. Conversely, PPARalpha upregulation preserved glucose-stimulated insulin secretion, essentially by increasing the response at a stimulatory concentration of glucose (15 mmol/l), a protection we also observed in human islets. The protective effect was associated with restored glucose oxidation rate and upregulation of the anaplerotic enzyme pyruvate carboxylase. PPARalpha overproduction increased both beta-oxidation and fatty acid storage in the form of neutral triacylglycerol, revealing overall induction of lipid metabolism. These observations were substantiated by expression levels of associated genes. CONCLUSIONS/INTERPRETATION: PPARalpha protected INS-1E beta cells from oleate-induced dysfunction, promoting both preservation of glucose metabolic pathways and fatty acid turnover.

The transcription factor PAX4 acts as a survival gene in INS-1E insulinoma cells.

The paired/homeodomain transcription factor Pax4 is essential for islet beta-cell generation during pancreas development and their survival in adulthood. High Pax4 expression was reported in human insulinomas indicating that deregulation of the gene may be associated with tumorigenesis. We report that rat insulinoma INS-1E cells express 25-fold higher Pax4 mRNA levels than rat islets. In contrast to primary beta-cells, activin A but not betacellulin or glucose induced Pax4 mRNA levels indicating dissociation of Pax4 expression from insulinoma cell proliferation. Short hairpin RNA adenoviral constructs targeted to the paired domain or homeodomain (viPax4PD and viPax4HD) were generated. Pax4 mRNA levels were lowered by 73 and 50% in cells expressing either viPax4PD or viPax4HD. Transcript levels of the Pax4 target gene bcl-xl were reduced by 53 and 47%, whereas Pax6 and Pdx1 mRNA levels were unchanged. viPax4PD-infected cells displayed a twofold increase in spontaneous apoptosis and were more susceptible to cytokine-induced cell death. In contrast, proliferation was unaltered. RNA interference-mediated repression of insulin had no adverse effects on either Pax4 or Pdx1 expression as well as on cell replication or apoptosis. These results indicate that Pax4 is redundant for proliferation of insulinoma cells, whereas it is essential for survival through upregulation of the antiapoptotic gene bcl-xl.

MAFA controls genes implicated in insulin biosynthesis and secretion.

AIMS/HYPOTHESIS: Effects of the transcription factor v-maf musculoaponeurotic fibrosarcoma oncogene homologue A (MAFA) on the regulation of beta cell gene expression and function were investigated. MATERIALS AND METHODS: INS-1 stable cell lines permitting inducible up- or downregulation of this transcription factor were established. RESULTS: MAFA overproduction enhanced and its dominant-negative mutant (DN-MAFA) diminished binding of the factor to the insulin promoter, correlating with insulin mRNA levels and cellular protein content. Glucose-stimulated insulin secretion was facilitated by MAFA and blunted by DN-MAFA. This is partly due to alterations in glucokinase production, the glucose sensor of beta cells. In addition, the expression of important beta cell genes, e.g. those encoding solute carrier family 2 (facilitated glucose transporter), member 2 (formerly known as GLUT2), pancreatic and duodenal homeobox factor 1 (PDX1), NK6 transcription factor-related, locus 1 (NKX6-1), glucagon-like peptide 1 receptor (GLP1R), prohormone convertase 1/3 (PCSK1) and pyruvate carboxylase (PC), was regulated positively by MAFA and negatively by DN-MAFA. CONCLUSIONS/INTERPRETATION: The data suggest that MAFA is not only a key activator of insulin transcription, but also a master regulator of genes implicated in maintaining beta cell function, in particular metabolism-secretion coupling, proinsulin processing and GLP1R signalling. Our in vitro study provides molecular targets that explain the phenotype of recently reported Mafa-null mice. We also demonstrate that MAFA is produced specifically in beta cells of human islets. Glucose influenced DNA-binding activity of MAFA in rat islets in a bell-shaped manner. MAFA thus qualifies as a master regulator of beta-cell-specific gene expression and function.

Ectopic expression of the beta-cell specific transcription factor Pdx1 inhibits glucagon gene transcription.

AIMS/HYPOTHESIS: The transcription factor Pdx1 is required for the development and differentiation of all pancreatic cells. Beta-cell specific inactivation of Pdx1 in developing or adult mice leads to an increase in glucagon-expressing cells, suggesting that absence of Pdx1could favour glucagon gene expression by a default mechanism. METHOD: We investigated the inhibitory role of Pdx1 on glucagon gene expression in vitro. The glucagonoma cell line InR1G9 was transduced with a Pdx1-encoding lentiviral vector and insulin and glucagon mRNA levels were analysed by northern blot and real-time PCR. To understand the mechanism by which Pdx1 inhibits glucagon gene expression, we studied its effect on glucagon promoter activity in non-islet cells using transient transfections and gel-shift analysis. RESULTS: In glucagonoma cells transduced with a Pdx1-encoding lentiviral vector, insulin gene expression was induced while glucagon mRNA levels were reduced by 50 to 60%. In the heterologous cell line BHK-21, Pdx1 inhibited by 60 to 80% the activation of the alpha-cell specific element G1 conferred by Pax-6 and/or Cdx-2/3. Although Pdx1 could bind three AT-rich motifs within G1, two of which are binding sites for Pax-6 and Cdx-2/3, the affinity of Pdx1 for G1 was much lower as compared to Pax-6. In addition, Pdx1 inhibited Pax-6 mediated activation through G3, to which Pdx1 was unable to bind. Moreover, a mutation impairing DNA binding of Pdx1 had no effect on its inhibition on Cdx-2/3. Since Pdx1 interacts directly with Pax-6 and Cdx-2/3 forming heterodimers, we suggest that Pdx1 inhibits glucagon gene transcription through protein to protein interactions with Pax-6 and Cdx-2/3. CONCLUSION/INTERPRETATION: Cell-specific expression of the glucagon gene can only occur when Pdx1 expression extinguishes from the early alpha cell precursor.

The SMN genes are subject to transcriptional regulation during cellular differentiation.

Proximal spinal muscular atrophy (SMA) is an autosomal recessive disease characterized by degeneration of alpha-motor neurons and muscular atrophy. The causal survival motor neuron (SMN) gene maps to a complex region of chromosome 5q13 harbouring an inverted duplication. Thus, there are two SMN genes, SMN1 and SMN2, but SMN1-deficiency alone causes SMA. In this study we demonstrate, for the first time, down-regulation of SMN promoter activity during cellular differentiation. Specifically, the minimal SMN promoter is four times more active in undifferentiated embryonal carcinoma P19 cells compared to cells treated with retinoic acid (RA) to initiate neuronal differentiation. This effect is mediated by sequences contained within the minimal core promoter that we have confined to the 257 nucleotides upstream of exon 1. We have identified seven regions that are highly conserved between the mouse and human SMN core promoters and this region contains the consensus sequence for a number of transcription factors. Most notably, AhR, HNF-3 and N-Oct3 have already been shown to respond to RA treatment of EC cells, while E47, HNF-3, MAZ, N-Oct3 and Pit-1a have been implicated in embryonic, muscle or neural development. In addition, we have mapped two strong transcription initiation sites upstream of SMN exon 1. The novel -79 site identified in this study is preferentially utilized during human foetal development. Furthermore, analysis of RNA from SMA patients with deletions of the entire SMN1 gene or chimpanzees that lack SMN2 suggests that the level of transcription initiation at these sites may be different for the SMN1 and SMN2 genes. Taken together, this work provides the first demonstration of transcriptional regulation of these genes during cellular differentiation and development. Deciphering the underlying mechanisms responsible for regulating SMN transcription may provide important clues towards enhancing SMN2 gene expression, one target for the treatment of SMA.

A combined PET/CT scanner for clinical oncology.

UNLABELLED: The availability of accurately aligned, whole-body anatomical (CT) and functional (PET) images could have a significant impact on diagnosing and staging malignant disease and on identifying and localizing metastases. Computer algorithms to align CT and PET images acquired on different scanners are generally successful for the brain, whereas image alignment in other regions of the body is more problematic. METHODS: A combined PET/CT tomograph with the unique capability of acquiring accurately aligned functional and anatomical images for any part of the human body has been designed and built. The PET/CT scanner was developed as a combination of a Siemens Somatom AR.SP spiral CT and a partial-ring, rotating ECAT ART PET scanner. All components are mounted on a common rotational support within a single gantry. The PET and CT components can be operated either separately, or in combined mode. In combined mode, the CT images are used to correct the PET data for scatter and attenuation. Fully quantitative whole-body images are obtained for an axial extent of 100 cm in an imaging time of less than 1 h. When operated in PET mode alone, transmission scans are acquired with dual 137Cs sources. RESULTS: The scanner is fully operational and the combined device has been operated successfully in a clinical environment. Over 110 patients have been imaged, covering a range of different cancers, including lung, esophageal, head and neck, melanoma, lymphoma, pancreas, and renal cell. The aligned PET and CT images are used both for diagnosing and staging disease and for evaluating response to therapy. We report the first performance measurements from the scanner and present some illustrative clinical studies acquired in cancer patients. CONCLUSION: A combined PET and CT scanner is a practical and effective approach to acquiring co-registered anatomical and functional images in a single scanning session.

Urinary riboflavin excretion after a load test in rural China as a measure of possible riboflavin deficiency.

Urinary excretion of riboflavin was measured in 3318 adults 4 h after an oral dose of riboflavin. Male and female subjects aged 35-64 years were selected from 65 mostly rural counties located in 24 provinces of China. Counties were selected to represent a range of seven of the most prevalent cancer mortality rates in China and within counties households were selected at random. Urinary riboflavin excretion levels after a load test, erythrocyte glutathione reductase activity coefficients (EGR-AC), dietary riboflavin intakes, and a large number of other biochemical, dietary, and environmental parameters were measured. Mean dietary intake of riboflavin was 75 per cent of the Chinese recommended dietary allowances (CRDA). Mean meat intake per reference man was very low (26.4 +/- 23.7 g/d) in comparison to Western standards and milk was not consumed at all in most counties. Mean EGR activity coefficients measured on 'blood pools' for both males (1.47 +/- 0.14) and females (1.48 +/- 0.16) indicated that more than two-thirds of the population surveyed was in the medium or high risk category of riboflavin deficiency. Using current reference standards of less than 1.4 mg for 4-h urinary excretion of riboflavin after a 5 mg load, more than 70 per cent of the individuals examined exhibited low levels usually associated with high risk of riboflavin deficiency. In view of the lack of specificity for clinical indications of riboflavin deficiency and the tentative validity of the present CRDA, the interpretation of the data is problematic. We suggest that the present CRDA for this vitamin is set too high and requires critical review and possibly some revision.

[Fatal acute cerebral edema in a diabetic child]. / Oedème cérébral aigu mortel chez un enfant diabétique.

A case is reported of fatal acute cerebral oedema occurring in a 15-year-old child suffering diabetic ketoacidosis. He had severe gastro-enteritis, with a weight lose of 8 kg over a period of 8 days (initial weight = 50 kg). He was admitted in a stupor with pH 7.15, 129 mmol.l-1 natraemia, and 31 mmol.l-1 blood glucose concentration. Blood osmolaity was calculated to be 310 mosmol.l-1. He was rehydrated with 416 ml.h-1 normal saline and 416 ml.h-1 of 1.4% sodium bicarbonate. At the same time a total dose of 75 i.u. of ordinary insulin was given. After 2 h, the patient's condition suddenly worsened with unreactive coma, bilateral fixed mydriasis, respiratory pauses, and impairment of haemodynamic state (heart rate 150 b.min-1, blood pressure 80/50 mmHg). The diagnosis of cerebral oedema with severe intracranial hypertension was confirmed by different investigations. Despite ventilatory support and continued intensive care, the patient died a few hours later. It is concluded that some degree of subclinical brain swelling could be common occurrence during diabetic ketoacidosis, present maybe even before the start of treatment. Such cases of cerebral oedema are often reported, but the pathophysiological mechanisms remain unclear. However, unlike this case, rehydration must be moderate (less than 41.m-2.day-1), especially in case of hyponatraemia. Insulin and sodium bicarbonate must be used with care. Early rigorous clinical and biological monitoring is essential. Treatment should aim at a progressive correction of the metabolic disturbances.