Fatma Abdelhedi

A Novel Nonsense Mutation in HSD17B3 Gene in a Tunisian Patient with Sexual Ambiguity

INTRODUCTION 17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) isoenzyme is present almost exclusively in the testes and converts delta 4 androstenedione to testosterone. Mutations in the HSD17B3 gene cause HSD17B3 deficiency and result in 46,XY Disorders of Sex Development (46,XY DSD). AIM This study aimed to present the clinical and biochemical features of a Tunisian patient who presented a sexual ambiguity orienting to HSD17B3 deficiency and to search for a mutation in the HSD17B3 gene by DNA sequencing. METHODS Polymerase chain reaction (PCR) amplification and subsequent sequencing of all the coding exons of HSD17B3 gene were performed on genomic DNA from the patient, her family, and 50 controls. RESULTS Genetic mutation analysis of the HSD17B3 gene revealed the presence of a novel homozygous nonsense mutation in the exon 9 (c.618 C>A) leading to the substitution p.C206X. The mutation p.C206X in the coding exons supports the hypothesis of HSD17B3 deficiency in our patient. CONCLUSION The patient described in this study represented a new case of a rare form of 46,XY DSD, associated to a novel gene mutation of HSD17B3 gene. The screening of this mutation is useful for confirming the diagnosis of HSD17B3 deficiency and for prenatal diagnosis.

Second Order Sliding Mode Based Synchronization Control for Cooperative Robot Manipulators

This work develops a modern controller design, combining reformulated second order sliding mode conception with the cross-coupling synchronizing approach. The goal behind the developed control architecture is to synchronize a group of robot manipulators while guaranteeing a performant trajectory tracking motion control. The developed robust approach allows not only to deal with sudden disturbances but also to avoid chattering phenomena yielded by acute discontinuous control signals. The Lyapunov-based analysis has been utilized to establish the multi-robot system asymptotic stability. Simulation results have been provided to demonstrate the performance of the adopted control schemes.

A novel TBX1 missense mutation in patients with syndromic congenital heart defects

Congenital heart defects represent a characteristic part of several genetic syndromes associated with chromosomal abnormalities such as 22q11.2 deletion syndrome; many genes located in this locus, mainly TBX1, are candidate genes for congenital heart defects. In our cohort of 27 subjects with congenital heart defect, both karyotype analysis and Fluorescence in situ hybridization (FISH) were performed. The TBX1 gene was sequenced in patients lacking chromosomal abnormalities. FISH analysis showed a de novo 22q11.2 deletion in two patients. The screening of TBX1 coding sequence identified a novel missense mutation c.569C > A (p.P190Q) in six unrelated patients and detected two associated known single nucleotide polymorphisms; the c.664C > T (rs2301558) in three patients and the c.420T > C (p.Phe140 Phe) (rs41298814) in one patient. Bioinformatic tools show that the novel missense mutation c.569C > A could modify the function and the stability of the TBX1 protein. The c.569C > A mutation was not found in 50 healthy controls. Ours results suggest a deleterious role of the c.569C > A mutation and strengthen the hypothesis that this mutation might be responsible for the same phenotype spectrum as the 22q11.2 deletion syndrome.

Adaptive second order sliding mode control under parametric uncertainties: application to a robotic system

The sliding mode control concept has been extensively investigated during the last decade, where it has been proved that such a control strategy is not so simple to be efficiently applied in dynamical and mechanical systems, because of the too strong sensitivity of such systems to the chattering phenomenon. In this paper, a reformulated second order sliding mode controller has been implemented into a robotic system for a trajectory tracking task, both in the case of ideal operation as well as for real systems submitted to parameter uncertainties. A comparative study performed through the obtained simulation results has been presented. Then, an adaptive extension of the second order sliding mode control has been treated seeking to resolve the challenging problems of real systems reflected by the presence of physical and environmental disturbances and especially parametric uncertainties. The proposed adaptive second order SMC has the advantage that it allows not only to remedy disturbing phenomena but also to retain all properties and system performances. Simulation results performed on a robotic manipulator system have illustrated improved performances with the proposed adaptive second order sliding mode control design.

Nonlinear PID and feedforward control of robotic manipulators

The purpose of this paper is to design a nonlinear PID controller for trajectory tracking of a manipulator robot. The objective is to develop a PID controller having high performances for the controllability and the stability of the manipulator. Moreover, the controller should be easy to implement. In a first step a PID plus a feedforward controller has been developed and implemented on a SCARA robot. In the second step and in order to increase performances of the developed control law, an improving version has been developed by adopting nonlinear gains. Simulation results show the effectiveness of the control law in particular in the presence of variable gains.

Insensibility of the Second Order Sliding Mode Control via Measurement Noises: Application to a Robot Manipulator Surveillance Camera

The Sliding Mode Control (SMC) is a widely spread approach thanks to its efficiency and robustness. However, it suffers from the undesirable chattering phenomenon which leads to the mechanical system damage. Then, this study takes into consideration the second order SMC which is known by its reliability regarding disturbances and nonlinear uncertainties, in order to improve the system stability and performances. In fact, such a high order SMC ensures a trade off between chattering reduction and disruption resistance. First, a second order sliding mode controller has been elaborated. Then, and in order to test the robustness of the proposed strategy, a measurement noise has been introduced. Simulation results show the efficiency of the proposed second order SMC applied to a robot manipulator system in a motion control task, which is used to ensure the displacement of a surveillance camera.

Synchronization of multi-robot manipulators based on high order sliding mode control

In this work, a synchronizing robust control approach is presented for the control of a multiple robot manipulators mouvements. The high order Sliding Mode Control(SMC) design is the base of this approach which is associated with the cross-coupling synchronization concept, whose aim is to ensure a performing trajectory tracking control whilst guaranteeing the movement synchronization of different system agents. Simulation results prove the efficiency of the proposed approach in realizing desired and unified tasks of the coordinated multi-robot system.

A surveillance camera algorithm based on the sliding mode approach with measurement's disturbance

The sliding mode control (SMC) is a variable structure, widely spread control strategy thanks to its efficient features such as robustness, easy implementation and reliability regarding disturbances and nonlinear uncertainties. Firstly, SMC has been implemented on a robot manipulator with three degrees of freedom used for a surveillance camera system. Then, and in order to improve the robustness of the proposed approach, an additive measurements noise has been introduced. Simulation results show the efficiency of the Sliding Mode Controller applied to a robot manipulator system in a motion control task, which is used to ensure the displacement of a surveillance camera.

Robust SMC for synchronization of networked time delay robotic systems

A finite time stability procedure is proposed for a networked robotic system, where it appears a disruptive time delay impact during the communication between system agents. Then, a distributed SMC algorithm in the presence of a delayed information exchange is discussed. The algorithm, which is derived from the cross coupling design and consensus theory, enables cooperative robots to accomplish a shared task and to compensate the communication time delay existence. Besides, the stability analysis of the SMC with synchronization of time delay multi-robot systems has been proved. Simulation results performed on a cooperative multi-agent system with constant communication time delays have illustrated good and satisfactory performances which verify the effectiveness of the SMC synchronizing algorithm and theoretical analysis.

Variabilité génétique des femmes XY : expérience du laboratoire de génétique moléculaire humaine de Sfax, Tunisie

LH exprimé dans les cellules de Leydig ; d’expression phénotypique limitée aux garçons. Cas rapporté.– Nous rapportons le cas de I.A., un garçon âgé de deux ans et sept mois. L’examen clinique retrouve un poids et une taille supérieurs à +3 D. Un stade de TANNER : G3P3 avec une verge supérieure à +2DS. L’âge osseux est de sept ans et le bilan hormonal e révèle un taux élevé de testostérone et un taux bas de FSH LH. Le test de LHRH et l’IRM hypothalamohypophysaire sont en faveur de l’origine périphérique. Les autres étiologies de l’origine périphérique ont été éliminées. L’étude génétique est en cours. Un traitement par kétoconazol a été démarré chez lui. Discussion.– La testotoxicose résulte d’une mutation activatrice du récepteur de LH chez le garçon, se manifestant par une grande taille, un agrandissement de la verge, une pilosité pubienne, et un âge osseux avancé compromettant la taille finale. Le kétoconazol est un moyen thérapeutique efficace à long terme sur le pronostic de la taille finale mais reste limité par ses effets indésirable. L’inhibiteur de l’aromatase seul ou en association aux antiandrogéniques s’est avéré efficace, mais son prix reste relativement cher. Le traitement de la testotoxicose est souvent compliqué par l’apparition d’une puberté précoce centrale nécessitant un traitement par agonistes de LHRH.