Structure of a multisubunit complex that promotes DNA branch migration.

The RuvA and RuvB proteins of Escherichia coli, which are induced in response to DNA damage, are important in the formation of heteroduplex DNA during genetic recombination and related recombinational repair processes. In vitro studies show that RuvA binds Holiday junctions and acts as a specificity factor that targets the RuvB ATPase, a hexameric ring protein, to the junction. Together, RuvA and RuvB promote branch migration, an ATP-dependent reaction that increases the length of the heteroduplex DNA. Electron microscopic visualization of RuvAB now provides a new insight into the mechanism of this process. We observe the formation of a tripartite protein complex in which RuvA binds the crossover and is sandwiched between two hexameric rings of RuvB. The Holliday junction within this complex adopts a square-planar structure. We propose a molecular model for branch migration, a unique feature of which is the role played by the two oppositely oriented RuvB ring motors.

Human GnRH deficiency: a unique disease model to unravel the ontogeny of GnRH neurons.

Evolutionary survival of a species is largely a function of its reproductive fitness. In mammals, a sparsely populated and widely dispersed network of hypothalamic neurons, the gonadotropin-releasing hormone (GnRH) neurons, serve as the pilot light of reproduction via coordinated secretion of GnRH. Since it first description, human GnRH deficiency has been recognized both clinically and genetically as a heterogeneous disease. A spectrum of different reproductive phenotypes comprised of congenital GnRH deficiency with anosmia (Kallmann syndrome), congenital GnRH deficiency with normal olfaction (normosmic idiopathic hypogonadotropic hypogonadism), and adult-onset hypogonadotropic hypogonadism has been described. In the last two decades, several genes and pathways which govern GnRH ontogeny have been discovered by studying humans with GnRH deficiency. More importantly, detailed study of these patients has highlighted the emerging theme of oligogenicity and genotypic synergism, and also expanded the phenotypic diversity with the documentation of reversal of GnRH deficiency later in adulthood in some patients. The underlying genetic defect has also helped understand the associated nonreproductive phenotypes seen in some of these patients. These insights now provide practicing clinicians with targeted genetic diagnostic strategies and also impact on clinical management.

Pyochelin enantiomers and their outer-membrane siderophore transporters in fluorescent pseudomonads: structural bases for unique enantiospecific recognition.

Pyochelin (Pch) and enantiopyochelin (EPch) are enantiomeric siderophores, with three chiral centers, produced under iron limitation conditions by Pseudomonas aeruginosa and Pseudomonas fluorescens , respectively. After iron chelation in the extracellular medium, Pch-Fe and EPch-Fe are recognized and transported by their specific outer-membrane transporters: FptA in P. aeruginosa and FetA in P. fluorescens . Structural analysis of FetA-EPch-Fe and FptA-Pch-Fe, combined with mutagenesis and docking studies revealed the structural basis of the stereospecific recognition of these enantiomers by their respective transporters. Whereas FetA and FptA have a low sequence identity but high structural homology, the Pch and EPch binding pockets do not share any structural homology, but display similar physicochemical properties. The stereospecific recognition of both enantiomers by their corresponding transporters is imposed by the configuration of the siderophore's C4'' and C2'' chiral centers. This recognition involves specific hydrogen bonds between the Arg91 guanidinium group and EPch-Fe for FetA and between the Leu117-Leu116 main chain and Pch-Fe for FptA. FetA and FptA are the first membrane receptors to be structurally described with opposite binding enantioselectivities for their ligands, giving insights into the structural basis of their enantiospecificity.

Fixed rings and strictures in Eosinophilic Esophagitis develop due to continuing inflammation over time

Background and Aims: Two distinct e ndoscopic phenotypes of E osinophilic Esophagitis (EoE) h ave been identified: t he inflammatory (IP) a nd the stenosing (SP) p henotype. I t is not known whether these EoE-associated phenotypes are reflective of different phases during disease course. We aimed to assess the phenotype a t initial EoE p resentation and d iagnosis and to evaluate if SP increases over time. Methods: R etrospective a nalysis of t he Swiss EoE Database (SEED) extended b y a review of p atients charts, endoscopy and pathology records. Results: F orty-four E oE p atients were a nalyzed (33 males, mean age at index visit 41 ± 14 years, all Caucasians). Median follow-up t ime was 3.1 years (IQR 1-4, r ange 1 -18 years). Median diagnostic delay w as 5 y ears (IQR 2-16, range 0-34 years). A t first diagnosis, 3 2% ( 14/44) o f EoE patients h ad already presented w ith a stenosis. T he mean d iameter o f the stenoses w as 1 0 ± 2 mm, and the mean length was 2 .8 ± 2 .9 cm. Peak e osinophil count d id n ot c hange over t ime (48 ± 39 eos/HPF at index visit vs. 59 ± 41 eos/HPF at end of follow-up, n=44). The risk of the presence of a stenosis at index visit was 0% f or a d isease duration of 0 -4 y ears, 37% f or a d isease duration between 5-10 years and 67% f or a d isease duration >10 years (p = 0.0035, trend test). Conclusions: T he frequency of e sophageal stenoses i s proportional to the disease duration, whereas the inflammatory activity does n ot s ignificantly c hange over t ime. O ur f indings underscore the necessity to reduce diagnostic delay in EoE and to control the underlying inflammatory processes to prevent esophageal remodeling.

TGFBI (BIGH3) gene mutations in German families: two novel mutations associated with unique clinical and histopathological findings.

BACKGROUND: To report the clinical, histopathological and immunohistochemical findings of two novel mutations within the TGFBI gene. METHODS: The genotype of 41 affected members of 16 families and nine sporadic cases was investigated by direct sequencing of the TGFBI gene. Clinical, histological and immunohistochemical characteristics of corneal opacification were reported and compared with the coding region changes in the TGFBI gene. RESULTS: A novel mutation Leu509Pro was detected in one family with a geographic pattern-like clinical phenotype. Histopathologically we found amyloid together with non-amyloid deposits and immunohistochemical staining of Keratoepithelin (KE) KE2 and KE15 antibodies. In two families and one sporadic case the novel mutation Gly623Arg with a late-onset, map-like corneal dystrophy was identified. Here amyloid and immunohistochemical staining of only KE2 antibodies occurred. Further, five already known mutations are reported: Arg124Cys Arg555Trp Arg124His His626Arg, Ala546Asp in 13 families and five sporadic cases of German origin. The underlying gene defect within the TBFBI gene was not identified in any of the four probands with Thiel-Behnke corneal dystrophy. CONCLUSIONS: The two novel mutations within the TGFBI gene add another two phenotypes with atypical immunohistochemical and histopathological features to those so far reported.

Insights into neuronal cell metabolism using NMR spectroscopy: uridyl diphosphate N-acetyl-glucosamine as a unique metabolic marker.

Making the switch: Compounds 1 and 2 are used as metabolic markers for NMR detection. When neuronal cells switch to a glycolytic state, an uneven distribution of (13) C in the N-acetyl group results, thus giving a mixture of the metabolites 1 and 2. It is therefore possible to monitor flux through different metabolic pathways, such as glycolysis, the tricarboxylic acid cycle, and the hexosamine biosynthetic pathway, using a single molecule.

Treatment of symphysitis pubis with one unique iv injection of Ibandronate: report of two cases

Objective: Osteitis pubis is a noninfectious painful inflammatorydisorder of the symphysis pubis. Etiologic factors are numerous, themost common are: osseous extension of adductor, enthesis due tosport overuse, irritation after urological and abdominal procedures,and systemic inflammatory disorders in particularspondylarthropathies. Many cases are idiopathic. The symptomsconsist of regional chronic mechanical and sometime nocturnal pain.Diagnosis is usually confirmed by either bone scintigraphy or by MRI.There are no standard treatments but conservative approachesincluding rest and NSAIDS are generally recommended. In 2001, agood clinical and radiological response of three refractory cases with3 to 6 monthly perfusions of pamidronate was reported [1].Ibandronate is a much more powerful and long-lasting bisphosphonatethan pamidronate, and has not yet been reported in literature to ourknowledge in this indication.Patients and Methods: We present two cases of idiopathic origin:one woman (63 years old) and one man (36 years old).The symptomswere present >3 months in the first patient and one year in the second.The diagnosis was confirmed by MRI which showed bone edemaon both sizes of symphysis and in the second case bony erosionsadjacent to the joint were seen. Both cases failed to respond toconservative measures. Both patients received one single direct ivInjection of 3 mg of Ibandronate.Results: The injections resulted in a rapid (within a few days)resolution of pain that lasted more than 6 months in both patients.No side effects were observed. In the first case, an isotope bone scanperformed 4 months after the injection showed no residual uptake. Thesecond patient had a repeated MRI after 6 months. It demonstrated anattenuation of bone edema compared to the first MRI.Conclusion: IV Ibandronate may constitute a safe and effectivetreatment option for patients with refractory osteitis pubis.References1 Maksymowych WP, Aaron SL, Russell AS. Treatment of refractorysymphysitis pubis with intravenous pamidronate. J Rheumatol.2001;28(12):2754, 2001.

RadA protein from Archaeoglobus fulgidus forms rings, nucleoprotein filaments and catalyses homologous recombination.

Proteins that catalyse homologous recombination have been identified in all living organisms and are essential for the repair of damaged DNA as well as for the generation of genetic diversity. In bacteria homologous recombination is performed by the RecA protein, whereas in the eukarya a related protein called Rad51 is required to catalyse recombination and repair. More recently, archaeal homologues of RecA/Rad51 (RadA) have been identified and isolated. In this work we have cloned and purified the RadA protein from the hyperthermophilic, sulphate-reducing archaeon Archaeoglobus fulgidus and characterised its in vitro activities. We show that (i) RadA protein forms ring structures in solution and binds single- but not double-stranded DNA to form nucleoprotein filaments, (ii) RadA is a single-stranded DNA-dependent ATPase at elevated temperatures, and (iii) RadA catalyses efficient D-loop formation and strand exchange at temperatures of 60-70 degrees C. Finally, we have used electron microscopy to visualise RadA-mediated joint molecules, the intermediates of homologous recombination. Intriguingly, RadA shares properties of both the bacterial RecA and eukaryotic Rad51 recombinases.

The European Respiratory Society spirometry tent: a unique form of screening for airway obstruction.

In order to raise public awareness of the importance of early detection of airway obstruction and to enable many people who had not been tested previously to have their lung function measured, the European Lung Foundation and the European Respiratory Society (ERS) organised a spirometry testing tent during the annual ERS Congresses in 2004-2009. Spirometry was performed during the ERS Congresses in volunteers; all participants answered a simple, brief questionnaire on their descriptive characteristics, smoking and asthma. Portable spirometers were freely provided by the manufacturer. Nurses and doctors from pulmonary departments of local hospitals/universities gave their service for free. Lower limit of normal (LLN) and Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria for diagnosing and grading airway obstruction were used. Of 12,448 participants in six congress cities, 10,395 (83.5%) performed acceptable spirometry (mean age 51.0 ± 18.4 yrs; 25.5% smokers; 5.5% asthmatic). Airway obstruction was present in 12.4% of investigated subjects according to LLN criteria and 20.3% according to GOLD criteria. Through multinomial logistic regression analysis, age, smoking habits and asthma were significant risk factors for airway obstruction. Relative risk ratio and 95% confidence interval for LLN stage I, for example, was 2.9 (2.0-4.1) for the youngest age (≤ 19 yrs), 1.9 (1.2-3.0) for the oldest age (≥ 80 yrs), 2.4 (2.0-2.9) for current smokers and 2.8 (2.2-3.6) for reported asthma diagnosis. In addition to being a useful advocacy tool, the spirometry tent represents an unusual occasion for early detection of airway obstruction in large numbers of city residents with an important public health perspective.

NOTES et trocart unique: révolution chirurgicale ou marketing [NOTES and single port access: surgical or marketing revolution?].

Promising new technologies are emerging in digestive surgery: Natural Orifice Transluminal Endoscopic Surgery (NOTES) and Single Port Access Surgery. They both aim to limit the surgical morbidity by decreasing the number of parietal accesses. The feasibility in human is obviously demonstrated, but numerous issues remain concerning the safety of these techniques. Furthermore, the expected advantages are not clearly demonstrated until now in the literature. In the future, it will be advisable to standardize techniques, in order to allow large clinical studies and to limit the potential complications of these approaches.