Receptors for anti-müllerian hormone on Leydig cells are responsible for its effects on steroidogenesis and cell differentiation

Strong overexpression of anti-Müllerian hormone (AMH) in transgenic mice leads to incomplete fetal virilization and decreased serum testosterone in the adult. Conversely, AMH-deficient mice exhibit Leydig cell hyperplasia. To probe the mechanism of action of AMH on Leydig cell steroidogenesis, we have studied the expression of mRNA for steroidogenic proteins in vivo and in vitro and performed a morphometric analysis of testicular tissue in mice overexpressing the hormone. We show that overexpression of AMH in male transgenic mice blocks the differentiation of Leydig cell precursors. Expression of steroidogenic protein mRNAs, mainly cytochrome P450 17 alpha-hydroxylase/C17-20 lyase (P450c17), is decreased in transgenic mice overexpressing AMH and in AMH-treated purified Leydig cells. In contrast, transgenic mice in whom the AMH locus has been disrupted show increase expression of P450c17. In vitro, but not in vivo, AMH also decreases the expression of the luteinizing hormone receptor. The effect of AMH is explained by the presence of its receptor on Leydig cells. Our results provide insight into the action of AMH as a negative modulator of Leydig cell differentiation and function.     

Vers les 20 kbit/s en transmission décamétrique ionosphérique : une application du traitement d’antenne sur des capteurs colocalisés

This paper presents an operational system of digital transmission within the h.f. frequency range, aiming at a significant increase of the data transfer rate compared with the current standard (4800 bit/s). Therefore, an array processing algorithm performs with a set of collocated sensors, the spatial responses of which are different one from each other. The dependence of the incoming polarization relatively to the direction of arrival induces a significant decorrelation of the received signals though no geometrical phase exists. Signal processing techniques run at the output of the spatial filter resorting for the synchronisation and the filtering (lms algorithm) to classical and well-tested techniques involving training sequences. An experimental radio link with a 250 km range has been set up to test the sensibility of the performances in reception regarding the choice of waveforms. The operational results reach the expected goal as the data transfer rate increases up to 20 kbit/s in a bandwidth of 6 kHz.     

Trial-spacing effects in Hermissenda suggest contributions of associative and nonassociative cellular mechanisms.

In behaving Hermissenda, a preparatory conditioned response developed across repeated pairings of light (conditioned stimulus; CS) and rotation (unconditioned stimulus; US) with intertrial intervals (ITIs) of 60 and 120 s, but not 30 s. Likewise, contiguous in vitro stimulation of the visual and vestibular receptors, an analog of behavioral conditioning, resulted in an increase in the input resistance (i.e., excitability, a correlate of conditioning) of the B photoreceptors of the Hermissenda's eye, but only with ITIs greater than 60 s. Calcium signaling in the B cell, critical to the induction of this neuronal plasticity, was attenuated with shorter ITIs owing to (a) a reduction of the light-induced generator potential and hence voltage-dependent Ca2+ influx during the light CS, (b) a depression of the Ca2+ current that persisted throughout shorter ITIs, and (c) a steady-state inactivation of the Ca2+ current as a result of a sustained depolarization persisting from the previous trial. These results are consistent with a 2-process theory of associative learning in which a primary process (Ca2+ influx) may be opposed by a secondary process (depression of the Ca2+ current) during short ITIs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The performance of materials management in multi-level product structures with demand uncertainty and back-ordering

This paper investigates the impact of planned backordering in the context of demand uncertainty for a multi-level product structure environment operating under a rolling horizon. To this end, the performance of lot sizing algorithms incorporating back-orders is evaluated for such an environment by means of simulation modeling. Given the presence of demand uncertainty, the results suggest that backordering algorithms can sometimes improve performance.     

A Vector-Controlled Cycloconverter Drive for an Icebreaker

A high-power high-performance variable-speed drive system using a cycloconverter-fed synchronous motor is described. The control uses the field-orientation principle to give the drive system good steady-state and dynamic performance criteria. The accuracy of the field orientation is improved with the use of current regulators operating in the airgap flux reference frame. The system was manufactured to deliver 16 000 hp to the twin propeller shafts of a Canadian Coast Guard icebreaker. The electric components of the system were tested as a unit in the factory and the desired system performance was achieved.     

Facilities planning and design with microcomputers

This paper describes an interactive layout design program, that is written in LISP and runs on IBM PC, XT, AT, or compatible microcomputers. This program follows a construction algorithm and generates a block diagram     

Parent training of toddlers in day care in low-income urban communities.

The authors tested a 12-week parent training program with parents (n=208) and teachers (n=77) of 2-3-year-olds in day care centers serving low-income families of color in Chicago. Eleven centers were randomly assigned to 1 of 4 conditions: (a) parent and teacher training (PT + TT), (b) parent training (PT), (c) teacher training (TT), and (d) waiting list control (C). After controlling for parent stress, PT and PT + TT parents reported higher self-efficacy and less coercive discipline and were observed to have more positive behaviors than C and TT parents. Among toddlers in high-risk behavior problem groups, toddlers in the experimental conditions showed greater improvement than controls. Most effects were retained 1 year later. Benefits were greatest when parents directly received training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Treatment of plasticized PVC to reduce plasticizer/solvent migration: optimization with an experimental design

This work deals with mass transfers between liquid food and PVC packaging. A treatment which reduces the migration both of plasticizer toward a liquid food simulant and the liquid has been investigated. The treatment is a two step process: (1) soaking in a liquid and (2) drying at various temperatures. Some process parameters, such as time and temperature of soaking, temperature and time of drying, influence the treatment efficacy. The best values consider in from these factors were found due to experimental designs and the physical significance of the results is discussed. © 2003 Society of Chemical Industry