An Iterative Nonribosomal Peptide Synthetase Assembles the Pyrrole-Amide Antibiotic Congocidine in Streptomyces ambofaciens

SummaryCongocidine (netropsin) is a pyrrole-amide (oligopyrrole, oligopeptide) antibiotic produced by Streptomyces ambofaciens. We have identified, in the right terminal region of the S. ambofaciens chromosome, the gene cluster that directs congocidine biosynthesis. Heterologous expression of the cluster and in-frame deletions of 8 of the 22 genes confirm the involvement of this cluster in congocidine biosynthesis. Nine genes can be assigned specific functions in regulation, resistance, or congocidine assembly. In contrast, the biosynthetic origin of the precursors cannot be easily inferred from in silico analyses. Congocidine is assembled by a nonribosomal peptide synthetase (NRPS) constituted of a free-standing module and several single-domain proteins encoded by four genes. The iterative use of its unique adenylation domain, the utilization of guanidinoacetyl-CoA as a substrate by a condensation domain, and the control of 4-aminopyrrole-2-carboxylate polymerization constitute the most original features of this NRPS

Cerebrospinal fluid and blood flow in mild cognitive impairment and Alzheimer's disease: a differential diagnosis from idiopathic normal pressure hydrocephalus

<p>Abstract</p> <p>Background</p> <p>Phase-contrast magnetic resonance imaging (PC-MRI) enables quantification of cerebrospinal fluid (CSF) flow and total cerebral blood (tCBF) flow and may be of value for the etiological diagnosis of neurodegenerative diseases. This investigation aimed to study CSF flow and intracerebral vascular flow in patients with Alzheimer's disease (AD) and patients with amnesic mild cognitive impairment (a-MCI) and to compare the results with patients with idiopathic normal pressure hydrocephalus (NPH) and with healthy elderly volunteers (HEV).</p> <p>Methods</p> <p>Ten a-MCI and 9 mild AD patients were identified in a comprehensive neurological and neuropsychological assessment. They underwent brain MRI; PC-MRI pulse sequence was performed with the following parameters: two views per segment; flip angle: 25° for vascular flow and 20° for CSF flow; field-of-view (FOV): 14 × 14 mm²; matrix: 256 × 128; slice thickness: 5 mm; with one excitation for exams on the 3 T machine, and 2 excitations for the 1.5 T machine exams. Velocity (encoding) sensitization was set to 80 cm/s for the vessels at the cervical level, 10 or 20 cm/s for the aqueduct and 5 cm/s for the cervical subarachnoid space (SAS). Dynamic flow images were analyzed with in-house processing software. The patients' results were compared with those obtained for HEVs (n = 12), and for NPH patients (n = 13), using multivariate analysis.</p> <p>Results</p> <p>Arterial tCBF and the calculated pulsatility index were significantly greater in a-MCI patients than in HEVs. In contrast, vascular parameters were lower in NPH patients. Cervical CSF flow analysis yielded similar values for all four populations. Aqueductal CSF stroke volumes (in μl per cardiac cycle) were similar in HEVs (34 ± 17) and AD patients (39 ± 18). In contrast, the aqueductal CSF was hyperdynamic in a-MCI patients (73 ± 33) and even more so in NPH patients (167 ± 89).</p> <p>Conclusion</p> <p>Our preliminary data show that a-MCI patients present with high systolic arterial peak flows, which are associated with higher mean total cerebral arterial flows. Aqueductal CSF oscillations are within normal range in AD and higher than normal in NPH. This study provides an original dynamic vision of cerebral neurodegenerative diseases, consistent with the vascular theory for AD, and supporting primary flow disturbances different from those observed in NPH.</p

Risk Factors of Inadequate Colposcopy After Large Loop Excision of the Transformation Zone: A Prospective Cohort Study

International audienceObjective: The aim of the study was to identify the risk factors of post-large loop excision of the transformation zone (LLETZ) inadequate colposcopy. Materials and Methods: From December 2013 to July 2014, a total of 157 patients who had a LLETZ performed for the treatment of high-grade intraepithelial lesion with fully visible cervical squamocolumnar junction were included. All procedures were performed using semicircular loops. The use of colposcopy made during each procedure was systematically documented. Dimensions and volume of LLETZ specimens were measured at the time of procedure, before formaldehyde fixation. All participants were invited for a follow-up colposcopy 3 to 6 months after LLETZ. Primary end point was the diagnosis of post-LLETZ inadequate colposcopy, defined by a not fully visible cervical squamocolumnar junction and/or cervical stenosis. Results: Colposcopies were performed in a mean (SD) delay of 136 (88) days and were inadequate in 22 (14%) cases. Factors found to significantly increase the probability of post-LLETZ inadequate colposcopy were a history of previous excisional cervical therapy [adjusted odds ratio (aOR) = 4.29, 95% CI = 1.12-16.37, p = .033] and the thickness of the specimen (aOR = 3.12, 95% CI = 1.02-9.60, p = .047). The use of colpos-copy for the guidance of LLETZ was statistically associated with a decrease in the risk of post-LLETZ inadequate colposcopy (aOR = 0.19, 95% CI = 0.04-0.80, p = .024) as the achievement of negative endocervical margins (aOR = 0.26, 95% CI = 0.08-0.86, p = .027). Conclusions: Although the risk of post-LLETZ inadequate colpos-copy is increased in patients with history of excisional therapy and with the thickness of the excised specimen, it could be reduced with the use of colposcopic guidance and the achievement of negative endocervical margins. L arge loop excision of the transformation zone (LLETZ) is a routine procedure worldwide, because it is the first-line treatment of high-grade intraepithelial lesion (HSIL) of the cervix. Quality criteria for optimal LLETZ include the completeness of excision with the achievement of negative margins, while producing the minimal excised volume and depth of excision to minimize subsequent obstetrical and neonatal morbidity. 1,2 Obtaining negative margins is important, because incomplete excision exposes women to a significant risk of posttreatment residual and/or recurrent disease, particularly when the lesion involves the endo-cervical canal. 3,4 However, this risk remains higher to the general female population, even when negative margins are achieved. Women who had had a LLETZ remain therefore exposed to a 3-to 4-fold increased risk of developing subsequent cervical cancer at least for 20 years. 5-8 Thus, prolonged and careful post-LLETZ follow-up is mandatory, whatsoever the margins status. For the last decade, the value of human papillomavirus testing has been demonstrated in this indication. Although a negative human papillomavirus test has now been admitted as the best test of cure for patients, colposcopy remains needed when this test is found to be positive. 9-12 Although being the key examination in this indication, the accuracy of colposcopy performed after previous excisional therapy of HSIL is however questionable because the healing process might result in changes in the appearance of the transformation zone (TZ). However, the main limitation of post-LLETZ colposcopic examination is the possibility of inadequate colposcopy due to the inability to visualize the entire TZ. Known risk factors for inadequate colposcopy include age, severity of lesion, and estrogen status of the patient. 13 However, inadequate colposcopy is also one of the main adverse effects of excisional therapies of the cervix, including LLETZ. 13 However, data on the precise risk factors for inadequate colposcopy after LLETZ are limited because most studies have focused on the sole risk of cervical stenosis without considering the position and visibility of the squamocolumnar junction. 14-17 This point is however crucial because it is clinically essential to identify how post-LLETZ inadequate colposcopy could be avoided, thus preserving the possibility for the follow-up of these women

Cyclodipeptide synthases, a family of class-I aminoacyl-tRNA synthetase-like enzymes involved in non-ribosomal peptide synthesis

Cyclodipeptide synthases (CDPSs) belong to a newly defined family of enzymes that use aminoacyl-tRNAs (aa-tRNAs) as substrates to synthesize the two peptide bonds of various cyclodipeptides, which are the precursors of many natural products with noteworthy biological activities. Here, we describe the crystal structure of AlbC, a CDPS from Streptomyces noursei. The AlbC structure consists of a monomer containing a Rossmann-fold domain. Strikingly, it is highly similar to the catalytic domain of class-I aminoacyl-tRNA synthetases (aaRSs), especially class-Ic TyrRSs and TrpRSs. AlbC contains a deep pocket, highly conserved among CDPSs. Site-directed mutagenesis studies indicate that this pocket accommodates the aminoacyl moiety of the aa-tRNA substrate in a way similar to that used by TyrRSs to recognize their tyrosine substrates. These studies also suggest that the tRNA moiety of the aa-tRNA interacts with AlbC via at least one patch of basic residues, which is conserved among CDPSs but not present in class-Ic aaRSs. AlbC catalyses its two-substrate reaction via a ping-pong mechanism with a covalent intermediate in which l-Phe is shown to be transferred from Phe-tRNAPhe to an active serine. These findings provide insight into the molecular bases of the interactions between CDPSs and their aa-tRNAs substrates, and the catalytic mechanism used by CDPSs to achieve the non-ribosomal synthesis of cyclodipeptides

The ANTENATAL multicentre study to predict postnatal renal outcome in fetuses with posterior urethral valves: objectives and design

Abstract Background Posterior urethral valves (PUV) account for 17% of paediatric end-stage renal disease. A major issue in the management of PUV is prenatal prediction of postnatal renal function. Fetal ultrasound and fetal urine biochemistry are currently employed for this prediction, but clearly lack precision. We previously developed a fetal urine peptide signature that predicted in utero with high precision postnatal renal function in fetuses with PUV. We describe here the objectives and design of the prospective international multicentre ANTENATAL (multicentre validation of a fetal urine peptidome-based classifier to predict postnatal renal function in posterior urethral valves) study, set up to validate this fetal urine peptide signature. Methods Participants will be PUV pregnancies enrolled from 2017 to 2021 and followed up until 2023 in >30 European centres endorsed and supported by European reference networks for rare urological disorders (ERN eUROGEN) and rare kidney diseases (ERN ERKNet). The endpoint will be renal/patient survival at 2 years postnatally. Assuming α = 0.05, 1–β = 0.8 and a mean prevalence of severe renal outcome in PUV individuals of 0.35, 400 patients need to be enrolled to validate the previously reported sensitivity and specificity of the peptide signature. Results In this largest multicentre study of antenatally detected PUV, we anticipate bringing a novel tool to the clinic. Based on urinary peptides and potentially amended in the future with additional omics traits, this tool will be able to precisely quantify postnatal renal survival in PUV pregnancies. The main limitation of the employed approach is the need for specialized equipment. Conclusions Accurate risk assessment in the prenatal period should strongly improve the management of fetuses with PUV

Place de l'analyse du segment ST de l'électrocardiogramme fœtal par le STAN® S 21 dans l'évaluation du bien-être fœtal au cours du travail (étude prospective à propos de 200 cas)

Cette étude prospective a été menée à la maternité d'Amiens, sur une période de 17 mois. Nous avons apprécié l'analyse du segment ST de l'ECG fœtal par l'appareil de surveillance STAN® S 21 lors d'anomalies du RCF en cours de travail. De nombreux paramètres ont été relevés sur un total de 200 dossiers. La naissance s'est effectuée dans 50% des cas par voie basse spontanée, dans 26,5% des cas par extraction instrumentale, et dans 23,5% des cas par césarienne. Le score d'Apgar à 5 minutes de vie était supérieur à 7 dans 97% des cas. On note depuis son utilisation une diminution du taux de césariennes pour souffrance fœtale aiguë, bien que celle-ci ne soit pas statistiquement significative (p=0,06). Nous avons relevé 6 cas d'acidose métabolique (pH artériel 12 mmol/l). Cependant, après relecture de ces dossiers, nous avons constaté 5 cas de " faux-négatifs ". De ce fait, le taux d'acidose métabolique non dépisté par l'appareil est de 0,5%. L'ensemble de ces résultats semble tout à fait prometteur, offrant une alternative sérieuse au pH au scalp, avec comme avantage supplémentaire le caractère continu de la surveillance du bien-être fœtalAMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Prise en charge des grossesses prolongées (évaluation de la surveillance du bien-être fœtal par l'enregistrement informatisé du rythme cardiaque fœtal (système Sonicaid Oxford 8002))

Objectif. Evaluer l'intérêt de la surveillance des grossesses prolongées par l'enregistrement informatisé du rythme cardiaque fœtal (RCF). Matériel et méthode. 194 patientes ayant dépassé le terme théorique de 41 SA ont été suivies par un examen clinique et un enregistrement informatisé du rythme cardiaque fœtal d'une durée de 30 minutes tous les deux jours jusqu'à l'accouchement. 248 enregistrements ont été réalisés. Une induction du travail était effectuée en cas de conditions cervicales favorables (score de Bishop>=6) ou de suspicion de souffrance fœtale. Les paramètres du dernier enregistrement informatisé ont été comparés à l'analyse du rythme cardiaque fœtal pendant le travail et à l'état acido-basique du nouveau-né à la naissance. Résultats. 11 fœtus avaient un pH artériel (pHa) à la naissance 15 bpm >15 secondes significativement plus fréquente. Les fœtus ayant une VCT43 minutes ainsi qu'une absence d'épisode de haute variation avaient un excès de base significativement diminué. Conclusion. Il existe une corrélation entre les paramètres de l'analyse informatisée du RCF et l'état acido-basique du nouveau-né à la naissance. La réalisation systématique d'un enregistrement informatisé du RCF pourrait permettre d'améliorer la prise en charge des fœtus en dépassement de terme théorique.AMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

DIAGNOSTIC ANTENATAL DES CARDIOPATHIES FOETALES. EN PICARDIE DE 1995 A 2000. ASPECT GYNECOOBSTETRICAUX

AMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Lésions précancéreuses de type CIN 2-3 et cancer du col de l'utérus pendant la grossesse (aspects diagnostiques et profils évolutifs, faisabilité de l'examen colposcopique : expérience au CHU d'Amiens et revue de la littérature)

Malgré le recul de l'incidence du cancer du col de l'utérus, on estime en France qu'une femme sur 10 000 est encore touchée par cette pathologie et que 30% de ces cancers sont diagnostiqués chez des femmes en âge de procréer donc susceptible d'avoir une grossesse. La grossesse constitue donc une une période majeure pour le dépistage du cancer du col utérin: par la réalisation de frottis cervico-utérin mais aussi par la prise en charge des lésions précancéreuses (CIN).A travers une étude rétrospective portant sur 64 patientes enceintes porteuses de lésions précancéreuses de CIN 2-3 mais aussi de lésions invasives, nous avons étudié les modalités diagnostiques, les profils évolutifs de ces lésions et la faisabilité de l'examen colposcopique. La colposcopie pendant la grossesse a tendance à surestimer la gravité des lésion, mais la corrélation colpo-histologique reste bonne et d'une sécurité suffisante. L'évolution des lésions précancéreuses au cours de la grossesse est marquée par une stabilité ou une régression. Les progressions sont rares mais la recherche d'un contingent infiltrant doit être réservé à un colposcopiste référent.AMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Attitude pratique face à une pyélectasie foetale à partir d'une étude rétrospective portant sur 131 patientes

Objectifs : Evaluer notre attitude actuelle en terme de prise en charge des pyélectasies foetales au Centre Pluridisciplinaire de Diagnostic Prénatal (CPDPN) du CHU d'Amiens, au travers dune étude rétrospective sur environ 5 ans, portant sur 131 patientes. Comparer nos pratiques et nos résultats ceux de la littérature. Enfin, proposer un protocole de service. Résultats : La pyélectasie foetale représente 3,15% des dossiers gérés au CPDPN. Les foetus masculins sont plus touchés avec un sex ratio à 3,7 / 1. Sur le versant du dépistage des anomalies chromosomiques, nous avons mis en évidence deux aneuploidies (une trisomie 13 et une trisomie18) ; il s'agissait de pyélectasies associées à d'autres signes échographiques. La littérature a confirmé l'importance des signes échographiques associés qui augmentent rapidement le risque d'anomalie chromosomique. En ce qui concerne la pyélectasie isolée, sa présence augmenterait le risque initial de trisomie 21 par un facteur 1,9. Entre 2002 et 2006, 30% des patientes consultant pour pyélectasie foetale isolée ont bénéficié d'un caryotype foetal. En terme de dépistage des uropathies, 25% des enfants, ayant présenté une pyélectasie, ont un diagnostic d'uropathies. Parmi eux, un enfant sur deux environ nécessitera un traitement chirurgical. Ces uropathies sont principalement les syndromes de la jonction pyélo urétérale, les reflux et les duplicités rénales. Conclusion : Nous proposons de limiter la réalisation du caryotype foetal, dans l'indication de pyélectasie isolée, par la pondération par un facteur 1,9 du risque initial de trisomie 21 obtenu par les marqueurs sériques ou l âge maternel ou la clarté nucaleAMIENS-BU Santé (800212102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF