Catherine Molinas

The vanZ gene of Tn1546 from enterococcus faecium BM4147 confers resistance to teicoplanin

A five-gene cluster from Tn1546 confers resistance to the glycopeptide antibiotics vancomycin (Vm) and teicoplanin (Te) by synthesis of pentadepsipeptide peptidoglycan precursors terminating in D-lactate, which replaces D-alanine in the same position of precursors utilized by susceptible enterococci. Cloning and nucleotide sequencing indicated that Tn1546 contains an additional gene, designated vanZ, which confers low-level Te resistance, in the absence of the genes required for pentadepsipeptide synthesis. Analysis of cytoplasmic peptidoglycan precursors, accumulated in the presence of ramoplanin, showed that VanZ-mediated Te resistance does not involve incorporation of a substituent of D-alanine into the precursors.

Hyperghrelinemia precedes obesity in Prader-Willi syndrome.

BACKGROUND High plasma ghrelin levels have been reported in Prader-Willi syndrome (PWS). However, little is known about plasma ghrelin in these children during the first years of life characterized by a failure to thrive. OBJECTIVE The objective of the study was to investigate total plasma ghrelin levels in children with PWS and controls from 2 months to 17 years. SUBJECTS AND METHODS Forty children with PWS [24 boys, 16 girls, median age 3.6 yr, median body mass index (BMI) Z-score 0.3] were compared with 84 controls (57 boys, 27 girls, median age 4.2 yr median BMI Z-score 0.1). Children were then divided into two groups according to age and GH treatment. RESULTS Median plasma ghrelin levels were significantly higher in children with PWS, compared with controls at any age (568 vs. 173, P < 0.0001) and decreased with age in both groups (P < 0.0001). In the whole group of PWS, we found an inverse relationship between ghrelin and BMI Z-score, insulin, homeostasis model assessment insulin resistance index, leptin, and lean mass. Plasma ghrelin levels were higher in children with PWS than controls, both in the youngest children below 3 yr who were not receiving GH (771 vs. 233, P < 0.0001) and in the children older than 3 yr, all of whom were treated with GH (428 vs. 159, P < 0.0001). CONCLUSIONS Plasma ghrelin levels in children with PWS are elevated at any age, including during the first years of life, thus preceding the development of obesity.

Scoliosis in Patients With Prader-Willi Syndrome

OBJECTIVE. Our goals were to determine the prevalence and estimate the evolution of spinal deformities in patients suffering from Prader-Willi syndrome; find out which kind of spine deformity predominates regarding genotype and clinical patterns; and evaluate the affect of growth-hormone treatment on the onset and progression of spinal deformities. PATIENTS AND METHODS. This was a retrospective longitudinal, clinical, and radiologic study. One hundred forty-five children followed between 1980 and 2006 were studied in 2 referral centers for Prader-Willi syndrome. Genetic testing confirmed the diagnosis in 133 patients. Ninety-three patients (64%) received growth-hormone therapy. For statistical analysis, age-adjusted comparison between groups was performed by using multivariate logistic regression. RESULTS. Mean age of the patients was 10.2 ± 6.2 years. Sixty-three (43.4%) patients were afflicted with scoliosis. Scoliosis frequency steadily rose with age, and a large majority of patients were affected at skeletal maturity (66.7%). Scoliosis prevalence was not affected by the genotype or by growth-hormone treatment. Patients with higher BMI values had an increased risk of developing a kyphotic deformity in association with scoliosis. We found a statistical association between kyphotic deformity and the need for surgical treatment. CONCLUSIONS. Scoliosis is a major concern for patients with Prader-Willi syndrome, and a regular (annual) systematic back examination is mandated. The role of growth-hormone treatment on the natural history of scoliosis could not be determined, and careful monitoring during treatment is recommended.

Prader-Willi syndrome as a model of human hyperphagia.

Prader-Willi syndrome (PWS), first described in 1956, is considered as a paradigm of a neurodevelopmental disorder with severe and early obesity with hyperphagia and impaired satiety. The improved knowledge in the natural history and recent data on genetics offer new perspectives for understanding the metabolic and endocrine dysfunctions and possibly for treatment. Natural history of the disease has been described due to the early diagnosis performed in the first months of life and various nutritional phases have been described. In addition, there is clear evidence that the abnormal feeding behavior is included in the behavioral problems. Brain imaging studies have shown that some brain regions may be important in PWS. The role of SNORD116 gene cluster is detailed and its links with circadian rhythm and brain and hypothalamus development. Pathophysiology of the abnormal ghrelin levels and of OT dysfunction is documented. While no effect on appetite and weight regulation has been reported with ghrelin antagonists, OT has been shown to improve some of the behavioral problems in adults. We discuss our hypothesis of an abnormal ghrelin/OT/dopamine pathway which may explain the switch of nutritional phases and behavior. These new aspects offer an opportunity for therapeutic use and possible early intervention.

Human growth hormone receptor: cloning and expression of the full-length complementary DNA after site-directed inactivation of a cryptic bacterial promoter

Growth hormone receptor is a cytokine-type receptor which is required for normal somatic growth and for numerous metabolic processes. Its complementary DNA (cDNA) has been isolated in various species leading to intensive studies to elucidate the mechanism of action of the growth hormone. However, serious difficulties have been reported in cloning in Escherichia coli, an intact full-length human cDNA. In this study, the cDNA is shown to contain a cryptic bacterial promoter driving inappropriate expression of a part of human growth hormone (hGH) receptor which is toxic for E. coli growth. Identification of this promoter and its inactivation by changing only one nucleotide led us to obtain stable bacterial clones containing a high copy number of full-length coding sequences. This molecular clone was used in a baculovirus/insect cell system to produce large amounts of glycosylated recombinant receptor. Binding studies with 125I-labelled hGH revealed an affinity constant of 2.8 x 10(9) M(-1), similar to that reported for the native liver receptor. This report described a general method of cloning which could be applied to similar unclonable cDNA fragments.

French database of children and adolescents with Prader-Willi syndrome.

BackgroundPrader-Willi syndrome (PWS) is a rare multisystem genetic disease leading to severe complications mainly related to obesity. We strongly lack information on the natural history of this complex disease and on what factors are involved in its evolution and its outcome. One of the objectives of the French reference centre for Prader-Willi syndrome set-up in 2004 was to set-up a database in order to make the inventory of Prader-Willi syndrome cases and initiate a national cohort study in the area covered by the centre.Descriptionthe database includes medical data of children and adolescents with Prader-Willi syndrome, details about their management, socio-demographic data on their families, psychological data and quality of life of the parents. The tools and organisation used to ensure data collection and data quality in respect of good clinical practice procedures are discussed, and main characteristics of our Prader-Willi population at inclusion are presented.Conclusionthis database covering all the aspects of PWS clinical, psychological and social profiles, including familial psychological and quality of life will be a powerful tool for retrospective studies concerning this complex and multi factorial disease and could be a basis for the design of future prospective multicentric studies. The complete database and the Stata.do files are available to any researcher wishing to use them for non-commercial purposes and can be provided upon request to the corresponding author.