Operational domain for the new 3MW/1000s ECRH System on WEST

The ECRH system formerly used in Tore Supra is being upgraded to start on WEST in 2023, at a power level of 1MW and frequency of 105 GHz. Its ultimate 3MW/1000s capability is expected to enlarge the WEST operational domain by increasing margins with respect to H-mode access, and by providing additional flexibility in terms of achievable scenarios using impurity and/or MHD control. This flexibility is made possible using an antenna based on three steerable mirrors for controlled power injection. In order to determine an appropriate range of EC wave injection angles for WEST scenarios, the fast and reliable ray-tracing code REMA has been interfaced with the WEST IMAS database. This allows the EC power damping rate to be quickly assessed, as well as deposition profiles to be predicted in realistic plasma conditions. Based on a typical WEST discharge at central magnetic field B0~3.6 T, central line-averaged electron density nl~4 × 1019 m−3 and central electron temperature Te0~3keV, ray-tracing calculations have been performed. Comprehensive poloidal and toroidal angle scans, as well as variations of Bt, nl and Te0 with respect to the reference parameters have allowed an adequate range of injection angles to be determined for efficient use of ECRH and/or ECCD in typical WEST scenarios, and compared with the mechanical limits set by the antenna mechanical characteristics. In order to further characterize the effect of this new power source in WEST scenarios, EC wave deposition and current profiles from ray-tracing calculations have been included in integrated simulation codes. It has been shown that this additional power source could allow central electron heating to be achieved, potentially alleviating the issue of radiative collapse caused by impurities observed in some situations.

Synaptic communication mediates the assembly of a self-organizing circuit that controls reproduction

Migration of gonadotropin-releasing hormone (GnRH) neurons from their birthplace in the nasal placode to their hypothalamic destination is critical for vertebrate reproduction and species persistence. While their migration mode as individual GnRH neurons has been extensively studied, the role of GnRH-GnRH cell communication during migration remains largely unexplored. Here, we show in awake zebrafish larvae that migrating GnRH neurons pause at the nasal-forebrain junction and form clusters that act as interhemisphere neuronal ensembles. Within the ensembles, GnRH neurons create an isolated, spontaneously active circuit that is internally wired through monosynaptic glutamatergic synapses into which newborn GnRH neurons integrate before entering the brain. This initial phase of integration drives a phenotypic switch, which is essential for GnRH neurons to properly migrate toward their hypothalamic destination. Together, these experiments reveal a critical step for reproduction, which depends on synaptic communication between migrating GnRH neurons.

Combining Cadherin Expression with Molecular Markers Discriminates Invasiveness in Growth Hormone and Prolactin Pituitary Adenomas

Although growth hormone (GH)- and prolactin (PRL)-secreting pituitary adenomas are considered benign, in many patients, tumour growth and/or invasion constitute a particular challenge. In other tumours, progression relies in part on dysfunction of intercellular adhesion mediated by the large family of cadherins. In the present study, we have explored the contribution of cadherins in GH and PRL adenoma pathogenesis, and evaluated whether this class of adherence molecules was related to tumour invasiveness. We have first established, by quantitative polymerase chain reaction and immunohistochemistry, the expression profile of classical cadherins in the normal human pituitary gland. We show that the cadherin repertoire is restricted and cell-type specific. Somatotrophs and lactotrophs express mainly E-cadherin and cadherin 18, whereas N-cadherin is present in the other endocrine cell types. This repertoire undergoes major differential modification in GH and PRL tumours: E-cadherin is significantly reduced in invasive GH adenomas, and this loss is associated with a cytoplasmic relocalisation of cadherin 18 and catenins. In invasive prolactinomas, E-cadherin distribution is altered and is accompanied by a mislocalisation of cadherin 18, β-catenin and p120 catenin. Strikingly, de novo expression of N-cadherin is present in a subset of adenomas and cells exhibit a mesenchymal phenotype exclusively in invasive tumours. Binary tree analysis, performed by combining the cadherin repertoire with the expression of a subset of known molecular markers, shows that cadherin/catenin complexes play a significant role in discrimination of tumour invasion.

The application of water soluble, mega-Stokes-shifted BODIPY fluorophores to cell and tissue imaging

BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) fluorophores are widely used in bioimaging to label proteins, lipids and nucleotides, but in spite of their attractive optical properties they tend to be prone to self-quenching because of their notably small Stokes shift. Herein, we compare two BODIPY compounds from a recently developed family of naphthyridine substituted BODIPY derivatives, one a visible emitting derivative (BODIPY-VIS) and one a near-infrared emitting fluorophore with a Stokes shift of approximately 165 nm as contrast reagents for live mammalian cells and murine brain tissue. The compounds were rendered water soluble by their conjugation to polyethylene glycol (PEG). Both PEGylated compounds exhibited good cell uptake compared with their parent compounds and confocal fluorescence microscopy revealed all dyes explored to be nuclear excluding, localizing predominantly within the lipophilic organelles; the endoplasmic reticulum and mitochondria. Cytotoxicity studies revealed that these BODIPY derivatives are modestly cytotoxic at concentrations exceeding 10 μM where they induce apoptosis and necrosis. Although the quantum yield of emission of the visible emitting fluorophore was over an order of magnitude greater than the Mega-Stokes shifted probe, the latter showed considerably reduced tendency to self quench and less interference from autofluorescence. The near-infrared probe also showed good penetrability and staining in live tissue samples. In the latter case similar tendency to exclude the nucleus and to localize in the mitochondria and endoplasmic reticulum was observed as in live cells. This to our knowledge is the first demonstration of such a Mega-Stokes BODIPY probe applied to cell and tissue imaging.

Anterior pituitary cell networks

Both endocrine and non-endocrine cells of the pituitary gland are organized into structural and functional networks which are formed during embryonic development but which may be modified throughout life. Structural mapping of the various endocrine cell types has highlighted the existence of distinct network motifs and relationships with the vasculature which may relate to temporal differences in their output. Functional characterization of the network activity of growth hormone and prolactin cells has revealed a role for cell organization in gene regulation, the plasticity of pituitary hormone output and remarkably the ability to memorize altered demand. As such, the description of these endocrine cell networks alters the concept of the pituitary from a gland which simply responds to external regulation to that of an oscillator which may memorize information and constantly adapt its coordinated networks' responses to the flow of hypothalamic inputs.

Investigating and modelling pituitary endocrine network function

Endocrine cells in the mammalian pituitary are arranged into three-dimensional homotypic networks that wire the gland and act to optimise hormone output by allowing the transmission of information between cell ensembles in a temporally precise manner. Despite this, the structure-function relationships that allow cells belonging to these networks to display coordinated activity remain relatively uncharacterised. This review discusses the recent technological advances that have allowed endocrine cell network structure and function to be probed and the mathematical models that can be used to analyse and present the resulting data. In particular, we focus on the mechanisms that allow endocrine cells to dynamically function as a population to drive hormone release as well as the experimental and theoretical methods that are used to track and model information flow through the network.

Role of maximal heart rate and arterial O2 saturation on the decrement of VO2max in moderate acute hypoxia in trained and untrained men

We aimed to evaluate 1) the altitude where maximal heart rate (HR (max)) decreases significantly in both trained and untrained subjects in moderate acute hypoxia, and 2) if the HR (max) decrease could partly explain the drop of V.O (2max). Seventeen healthy males, nine trained endurance athletes (TS) and eight untrained individuals (US) were studied. Subjects performed incremental exercise tests at sea level and at 5 simulated altitudes (1000, 1500, 2500, 3500, 4500 meters). Power output (PO), heart rate (HR), arterial oxygen saturation (SaO (2)), oxygen uptake (V.O (2)), arterialized blood pH and lactate were measured. Both groups showed a progressive reduction in V.O (2max). The decrement in HR (max) (DeltaHR (max)) was significant from 1000 m for TS and 2500 m for US and more important in TS than US (at 1500 m and 3500 m). At maximal exercise, TS had a greater reduction in SaO (2) (DeltaSaO (2)) at each altitude. DeltaHR (max) observed in TS was correlated with DeltaSaO (2). When the two groups were pooled, simple regressions showed that DeltaV.O (2max) was correlated with both DeltaSaO (2) and DeltaHR (max). However, a multiple regression analysis demonstrated that DeltaSaO (2) alone may account for DeltaV.O (2max). Furthermore, in spite of a greater reduction in SaO (2) and HR (max) in TS, no difference was evidenced in relative DeltaV.O (2max) between groups. Thus, in moderate acute hypoxia, the reduction in SaO (2) is the primary factor to explain the drop of V.O (2max) in trained and untrained subjects.

Moderate exercise in hypoxia induces a greater arterial desaturation in trained than untrained men

During moderate exercise breathing a low inspired O(2) fraction (F(I)O(2)), arterial O(2) desaturation may depend on the fitness level. Seven trained (TM) and seven untrained men (UTM) cycled in normoxia and in hypoxia (F(I)O(2)=0.187, 0.173, 0.154, 0.13 and 0.117). We compared TM and UTM at submaximal intensities below the ventilatory threshold. Ventilatory variables were monitored and arterial oxygen saturation was measured by pulse oximetry. O(2) saturation was not different between groups at sea level. In hypoxia, O(2) saturation was lower in TM than in UTM at F(I)O(2)=0.154 (87.3 +/- 2.9% vs 90.4 +/- 1.5% at 90 W) and below. Both the ventilatory-equivalent and the end-tidal O(2) pressure were lower in TM at sea level and at every F(I)O(2), with the differences between TM and UTM becoming apparent at lower exercise intensity and increasing in magnitude as the severity of hypoxia increased. O(2) saturation was correlated with the ventilatory parameters at every F(I)O(2) and the correlations were stronger in severe hypoxia. These results demonstrate that a moderate exercise carried out in hypoxia, contrary to normoxic conditions, can lead to a greater arterial desaturation in TM compared with UTM. This phenomenon could be partly attributed to a relative hypoventilation in trained subjects.

Long-term results of bladder neck reconstruction for incontinence in children with classical bladder exstrophy or incontinent epispadias

OBJECTIVE

To review the long-term results of bladder neck reconstruction (BNR) in patients with classical bladder exstrophy or epispadias, and to review the concept of continence surgery in these two groups, stressing the difficulty in finding an adequate balance between urine storage (which implies high outlet resistance and low storage pressure) and complete bladder emptying (which implies low outlet resistance and a transient increase in bladder pressure); surgery cannot achieve 'continence' (which implies active mechanisms) but only 'dryness' (which implies passive mechanisms).

PATIENTS AND METHODS

Eighty patients with classical bladder exstrophy (52 male, 28 female) and 25 with incontinent epispadias (17 male, 18 female) had their bladder neck reconstructed after a Young-Dees-Leadbetter procedure, subsequently modified by Mollard. The treatment is detailed and results reviewed after a mean follow-up of 11 years. All patients were treated and followed in the same institution.

RESULTS

In the exstrophy group, 36 (45%) patients presented with a dry interval of > 3 h, with urethral emptying after one BNR; 52 (65%) presented with recurrent urinary tract infections, 19 (24%) with urinary stones, 21 (26%) with dilated upper urinary tracts, 13 (16%) with bladder perforations and one with an adenocarcinoma of the bladder. Thirty-eight patients (48%) required further surgery; 51% of all patients required an endoscopic procedure within 3 months after the BNR and 26% had endoscopic procedures for late (> 3 months) urine retention. In the epispadias group, 13 (52%) patients presented with a dry interval of > 3 h with urethral emptying after one BNR; 12 (48%) had recurrent urinary tract infections, five (20%) upper tract dilatation, two (8%) bladder stones, one (4%) bladder perforation and one an adenocarcinoma of the bowels after a ureterosigmoidostomy. Ten (40%) children required further surgery.

CONCLUSION

We compared the present results for continence with those in other published series; most complications encountered were related to the obstructive pattern of bladder emptying and the abnormal bladder urodynamic behaviour caused by BNR. We consider that BNR is unpredictable and the roles of the other factors in urinary continence are discussed. Alternative procedures are detailed. The concept of continence surgery in exstrophy and incontinent epispadias is reviewed, stressing the importance of favouring bladder development and limiting obstructive patterns of bladder emptying that cause severe and recurrent complications.

Growth hormone-releasing hormone (GHRH) neurons in GHRH-enhanced green fluorescent protein transgenic mice: a ventral hypothalamic network

The hypothalamic GHRH neurons secrete pulses of GHRH to generate episodic GH secretion, but little is known about the mechanisms involved. We have made transgenic mice expressing enhanced green fluorescent protein (eGFP) specifically targeted to the secretory vesicles in GHRH neurons. GHRH cells transported eGFP from cell bodies in the arcuate nucleus to extensively arborized varicose fiber terminals in the median eminence. Patch clamp recordings from visually identified GHRH cells in mature animals showed spontaneous action potentials, often firing in short bursts up to 10 Hz. GHRH neurons received frequent synaptic inputs, as demonstrated by the recording of abundant inward postsynaptic currents, but spikes were followed by large after-hyperpolarizations, which limited their firing rate. Because many GHRH neurons lie close to the ventral hypothalamic surface, this was examined by wide-field binocular epifluorescence stereomicroscopy. This approach revealed an extensive horizontal network of GHRH cells at low power and individual fiber projections at higher power in the intact brain. It also showed the dense terminal projections of the GHRH cell population in the intact median eminence. This model will enable us to characterize the properties of individual GHRH neurons and their structural and functional connections with other neurons and to study directly the role of the GHRH neuronal network in generating episodic secretion of GH.

Folliculostellate cell network: a route for long-distance communication in the anterior pituitary

All higher life forms critically depend on hormones being rhythmically released by the anterior pituitary. The proper functioning of this master gland is dynamically controlled by a complex set of regulatory mechanisms that ultimately determine the fine tuning of the excitable endocrine cells, all of them heterogeneously distributed throughout the gland. Here, we provide evidence for an intrapituitary communication system by which information is transferred via the network of nonendocrine folliculostellate (FS) cells. Local electrical stimulation of FS cells in acute pituitary slices triggered cytosolic calcium waves, which propagated to other FS cells by signaling through gap junctions. Calcium wave initiation was because of the membrane excitability of FS cells, hitherto classified as silent cells. FS cell coupling could relay information between opposite regions of the gland. Because FS cells respond to central and peripheral stimuli and dialogue with endocrine cells, the form of large-scale intrapituitary communication described here may provide an efficient mechanism that orchestrates anterior pituitary functioning in response to physiological needs.

A secreted fluorescent reporter targeted to pituitary growth hormone cells in transgenic mice

In stable transfection experiments in the GH-producing GC cell line, a construct containing the entire signal peptide and the first 22 residues of human GH linked in frame with enhanced green fluorescent protein (eGFP), produced brightly fluorescent cells with a granular distribution of eGFP. This eGFP reporter was then inserted into a 40-kb cosmid transgene containing the locus control region for the hGH gene and used to generate transgenic mice. Anterior pituitaries from these GH-eGFP transgenic mice showed numerous clusters of strongly fluorescent cells, which were also immunopositive for GH, and which could be isolated and enriched by fluorescence-activated cell sorting. Confocal scanning microscopy of pituitary GH cells from GH-eGFP transgenic mice showed a markedly granular appearance of fluorescence. Immunogold electron microscopy and RIA confirmed that the eGFP product was packaged in the dense cored secretory vesicles of somatotrophs and was secreted in parallel with GH in response to stimulation by GRF. Using eGFP fluorescence, it was possible to identify clusters of GH cells in acute pituitary slices and to observe spontaneous transient rises in their intracellular Ca2+ concentrations after loading with Ca2+ sensitive dyes. This transgenic approach opens the way to direct visualization of spontaneous and secretagogue-induced secretory mechanisms in identified GH cells.

[Treatment of neurogenic urinary incontinence in children]

The current management of neurogenic urinary incontinence is exclusively urological and therefore palliative. However, urological techniques have considerably advanced over the last 20 years and now allow continence with protection of the upper urinary tract in the very great majority of cases. The authors review the various techniques proposed in achieve acceptable continence and define the indications based on published results and their personal experience.

Transureteroureterostomy in childhood and adolescence: long-term results in 69 cases

PURPOSE

We analyzed a series of 69 transureteroureterostomies to evaluate long-term results and specify current indications.

MATERIALS AND METHODS

Between 1969 and 1998 transureteroureterostomy was performed in 32 females and 37 males with a mean age of 8.6 years. Surgery was done to avoid repeat or difficult ureteral reimplantation after multiple failed procedures in 22 cases and to create a continent ureteral conduit for intermittent catheterization in 23. Other indications included undiversion in 8 cases, ureterocystoplasty in 6, diversion in 4, the Kropp procedure in 3, massively dilated megaureter in 2 and ureteral necrosis in 1. Of the 69 patients 6 were lost to followup and 63 were followed at least 1 year (median 6).

RESULTS

A total of 63 patients were regularly monitored by clinical observation and morphological investigation, including ultrasound, excretory urography and cystography. In 50 cases (79.4%) results were good with no upper urinary tract dilatation. All initially normal donor ureters remained normal. Of 51 initially dilated donor ureters 40 (78.4%) improved or returned to normal, while 20 of 27 initially dilated recipient ureters (74.1%) improved or returned to normal. Serious complications in 3 cases (4.3%) involved anastomotic leakage, ischemic stenosis of the common ureteral trunk and progressive deterioration of function in 1 kidney requiring nephrectomy 3 years postoperatively. Reoperation was successful in the former 2 cases.

CONCLUSIONS

With careful attention to technique transureteroureterostomy represents a safe and reliable procedure with well-defined indications in pediatric urology.

Rhythmic bursts of calcium transients in acute anterior pituitary slices

Endocrine cells isolated from the anterior pituitary fire intracellular Ca2+ ([Ca2+]i) transients due to voltage-gated Ca2+ entry. However, the patterns of [Ca2+]i transients within the glandular parenchyma of the anterior pituitary are unknown. Here we describe, using real-time confocal laser microscopy, several spontaneous patterns of calcium signaling in acute pituitary slices prepared from male as well as cycling and lactating female rats. Forty percent of the cells demonstrated a spontaneous bursting mode, consisting of an active period of [Ca2+]i transients firing at a constant frequency, followed by a rest period during which cells were either silent or randomly active. The remaining recordings from endocrine cells either demonstrated random [Ca2+]i transients or were silent. These rhythmic bursts of [Ca2+]i transients, which required extracellular calcium, were detected in lactotrophs, somatotrophs, and corticotrophs within the acute slices. Of significance was the finding that the bursting mode could be adjusted by hypothalamic factors. In slices prepared from lactating rats, TRH recruited more bursting cells and finely adjusted the average duty cycle of [Ca2+]i bursts such that cells fired patterned bursts for approximately 70% of the recording period. Eighty-six percent of these cells were lactotrophs. Thus, the rhythmic [Ca2+]i bursts and their tuning by secretagogues may provide timing information that could encode for one or more cellular functions (e.g. exocytosis and/or gene expression) critical for the release of hormones by endocrine cells in the intact gland.

Potential role for triglycerides in signal transduction

We previously reported that endothelin-1 or platelet-derived growth factor promoted in aortic smooth muscle cells a rapid hydrolysis of 1-O-alkyl-2-acyl-sn-glycero-3-phosphoethanolamine (alkyl-PE) which was immediately converted into 1-O-alkyl-2,3-diacyl-sn-glycerol (alkyl-TG) within 5 s or 60 s respectively [C. Comminges et al. (1996) Biochem. Biophys. Res. Commun. 220, 1008-1013 and C. Comminges et al. (1997) Biochim. Biophys. Acta 1355, 69-80]. In this study, we show that this alkyl-PE hydrolysis is triggered by a transient activation of a specific phospholipase C (PLC) regulated by pertussis toxin-sensitive heterotrimeric G-proteins. Moreover, this PLC can be triggered through a Ca2+ influx depending on L-type Ca2+ channel activation, as suggested by the use of a specific 'activator' S(-)-BayK 8644 and of selective inhibitors such as nimodipine. Interestingly, low concentrations (10(-8)-10(-7)M) of alkyl-TG block the opening of L-type Ca2+ channels, whereas identical concentrations of DG do not alter L-type Ca2+ channels. This study thus unravels a hitherto unrecognized signaling pathway generating alkyl-TG as a novel lipid second messenger, potentially acting as a negative feedback regulator of L-type Ca2+ channels.

Modulation of pancreatic acinar cell to cell coupling during ACh-evoked changes in cytosolic Ca2+

The temporal changes in cytosolic free Ca2+ ([Ca2+]i), Ca2+-dependent membrane currents (Im), and gap junctional current (Ij) elicited by acetylcholine (ACh) were measured in rat pancreatic acinar cells using digital imaging and dual perforated patch-clamp recording. ACh (50 nM-5 microM) increased [Ca2+]i and evoked Im currents without altering Ij in 19 of 37 acinar cell pairs. Although [Ca2+]i rose asynchronously in cells comprising a cluster, the delay of the [Ca2+]i responses decreased with increasing ACh concentrations. Perfusion of inositol 1,4,5-trisphosphate (IP3) into one cell of a cluster resulted in [Ca2+]i responses in neighboring cells that were not necessarily in direct contact with the stimulated one. This suggests that extensive coupling between acinar cells provides a pathway for cell-to-cell diffusion of Ca2+-releasing signals. Strikingly, maximal (1-5 microM) ACh concentrations reduced Ij by 69 +/- 15% (n = 9) in 25% of the cell pairs subjected to dual patch-clamping. This decrease occurred shortly after the Im peak and was prevented by incubating acinar cells in a Ca2+-free medium, suggesting that uncoupling was subsequent to the initiation of the Ca2+-mobilizing responses. Depletion of Ca2+-sequestering stores by thapsigargin resulted in a reduction of intercellular communication similar to that observed with ACh. In addition, ACh-induced uncoupling was prevented by blocking nitric oxide production with L-nitro-arginine and restored by exposing acinar cells to dibutyryl cGMP. The results suggest that ACh-induced uncoupling and capacitative Ca2+ entry are regulated concurrently. Closure of gap junction channels may occur to functionally isolate nearby cells differing in their intrinsic sensitivity to ACh and thereby to allow for sustained activity of groups of secreting cells.

[Urethral lengthening (the Kropp technic) in neurologic urinary incontinence in children and adolescents. Results of a series of 22 cases]

In 1986 Kropp et Angwafo described a technique of urethral lengthening for the treatment of urinary incontinence in children with neurogenic bladders. We have used a modified version of this procedure in 22 girls between 1986 and 1990. Here we report its mid and long term effects on continence. The problems we have encountered in these patients are discussed.

[Proximal hypospadias]

OBJECTIVE

To evaluate the outcome of surgery in posterior hypospadias.

METHOD

The technique of preservation of the urethral plate is described following three main steps: 1.-The first step is the correction of chordee which is mainly related to the two fibrous and vascular pillars sitting on each side of the urethral plate and representing the division of the atretic corpus spongiosum. Tethering of the urethral plate onto the anterior surface of the corpora cavernosa is another common cause of chordee which can be relieved by untethering the urethral plate from the ectopic meatus up to the glans cap. The urethral plate can be preserved in most cases of posterior hypospadias (35/43) and dorsal plication of the corpora cavernosa is rarely needed. 2.- The second step of this surgery is urethroplasty, which is usually achieved by using a pediculized preputial patch stitched to the urethral plate (onlay urethroplasty). 3.- Penile cover using the skin sleeve technique completes the procedure.

RESULTS

Twenty one per cent fistulae, 1 meatal stenosis, no proximal stenosis are reported and discussed.

CONCLUSION

Preservation of the urethral plate is possible in most posterior hypospadias and permits an onlay urethroplasty which remains to date the most reliable procedure to reconstruct the urethra in posterior hypospadias.

Male epispadias: experience with 45 cases

PURPOSE

We evaluate the long-term results of surgery for isolated (without exstrophy) male epispadias.

MATERIALS AND METHODS

A total of 45 male patients with isolated epispadias were treated and followed at Debrousse Hospital between 1971 and 1993, 8 in whom repairs performed elsewhere had failed and 14 had total urinary incontinence. Incontinence was treated with a modified Young-Dees reconstruction of the bladder neck and the ureters were reimplanted in all cases. Long-term followup was available in 18 cases of a Cantwell-Young-Gross, 4 Duplay, 7 full thickness skin graft, 1 bladder graft and 10 Cantwell-Ransley urethroplasties. Penile reconstruction was performed using a 2-stage procedure in 8 patients (freeing of the corpora followed by urethroplasty), and an isolated urethroplasty in 13. All other patients underwent a single stage repair combining dissection of the penis and urethroplasty.

RESULTS

All patients were reassessed clinically. Of 13 incontinent patients followed for 1 to 20 years 11 acquired continence, 1 remains incontinent and 1 underwent a repeat procedure recently. Urethroplasty was immediately satisfactory in 66% of the cases, minor complications developed in 25% and serious complications (especially free graft urethroplasty) developed in 10%. Assessment of genital cosmesis is subjective but it was considered acceptable in most cases. All 29 patients with long-term followup had erections, 24 performed regular sexual intercourse, 17 had normal ejaculations and 4 fathered children.

CONCLUSIONS

The principles described by Cantwell-Young and Gross, and modified by Ransley, have considerably improved penile reconstruction. Free graft and Duplay urethroplasties provided unacceptable results in our series. Our results of surgery for incontinence associated with isolated male epispadias (84%) were better than for male exstrophy (63%).

Tubocurarine blocks a calcium-dependent potassium current in rat tumoral pituitary cells

We investigated the effects of potassium channel inhibitors on electrical activity, membrane ionic currents, intracellular calcium concentration ([Ca2+]i) and hormone release in GH3/B6 cells (a line of pituitary origin). Patch-clamp recordings show a two-component after hyperpolarization (AHP) following each action potential (current clamp) or a two-component tail current (voltage-clamp). Both components can be blocked by inhibiting Ca2+ influx. Application of D-tubocurarine (dTc) (20-500 microM) reversibly suppressed the slowly decaying Ca2+-activated K+ tail current (I AHPs) in a concentration-dependent manner. On the other hand, low doses of tetraethylammonium ions (TEA+) only blocked the rapidly decaying voltage- and Ca2+-activated K+ tail current (I AHPf). Therefore, GH3/B6 cells exhibit at least two quite distinct Ca2+-dependent K+ currents, which differ in size, voltage- and Ca2+-sensitivity, kinetics and pharmacology. These two currents also play quite separate roles in shaping the action potential. d-tubocurarine increased spontaneous Ca2+ action potential firing, whereas TEA increased action potential duration. Thus, both agents stimulated Ca2+ entry. I AHPs is activated by a transient increase in [Ca2+]i such as a thyrotrophin releasing hormone-induced Ca2+ mobilization. All the K+ channel inhibitors we tested: TEA, apamin, dTC and charybdotoxin, stimulated prolactin and growth hormone release in GH3/B6 cells. Our results show that I AHPs is a good sensor for subplasmalemmal Ca2+ and that dTc is a good pharmacological tool for studying this current.

Synchronized spontaneous Ca2+ transients in acute anterior pituitary slices

We investigated the organization of spontaneous rises in cytosolic free Ca2+ concentration ([Ca2+]i) due to electrical activity in acute pituitary slices. Real time confocal imaging revealed that 73% of the cells generated fast peaking spontaneous [Ca2+]i transients. Strikingly, groups of apposing cells enhanced their [Ca2+]i in synchrony with a speed of coactivation >1,000 microm/s. Single-cell injection of Neurobiotin or Lucifer yellow labeled clusters of cells, which corresponded to coactive cells. Halothane, a gap junction blocker, markedly reduced the spread of tracers. Coupling between excitable cells was mainly homologous in nature, with a prevalence of growth hormone-containing cells. We conclude that spontaneously active endocrine cells are either single units or arranged in synchronized gap junction-coupled assemblies scattered throughout the anterior pituitary gland. Synchrony between spontaneously excitable cells may help shape the patterns of basal secretion.

Visualization of cyclic AMP-regulated presynaptic activity at cerebellar granule cells

Adenylyl cyclase (AC) modulation of vesicular cycling was visualized at cultured cerebellar granule cell synapses using the sequential uptake of antibodies directed against the intraluminal domain of synaptotagmin I. Vesicle recycling due to spontaneous transmitter release in the absence of action potentials was increased by the AC/protein kinase A (PKA) activators forskolin and CPT-cAMP. These effects were blocked by the PKA inhibitor Rp-cAMPs. Cyclic AMP elevation also induced new cycling at previously silent sites. Activation of L-AP4-sensitive mGluR reduced the cAMP/PKA enhancement at preexisting synapses downstream of both AC and calcium channels. Modulation of the turnover and the number of vesicular release sites provide one mechanism that may underlie cAMP-dependent cerebellar long-term potentiation.

Female epispadias

PURPOSE

We assessed the incidence, anatomical features and treatment of female epispadias.

MATERIALS AND METHODS

We studied 10 patients followed from 1 to 18 years. Four were operated on in 2 stages: first, cervicoplasty with original technique, and second, reconstruction of genitalia and distal urethra. Two had only a cervicoplasty. The last 4 patients were operated on in 1 stage according to Hendren's technique but with a simplified cervicoplasty.

RESULTS

Eight of 10 patients are totally continent, 1 has some small nocturnal leakage, and 1 is incontinent but the interval of dryness is increasing and is longer than 1 hour. Concerning external genitalia, the result is good but not perfect.

CONCLUSIONS

Female epispadias is most often complete with total incontinence. The aim of treatment is to reconstruct the anatomy in 1 stage. Treatment is easier and the results are better than in cases of female exstrophy or male incontinent epispadias.

Organotypic cultures of the rat anterior pituitary: morphology, physiology and cell-to-cell communication

Organotypic cultures, prepared from young rats, were used to investigate the neuroendocrine properties of anterior pituitary cells. Pituitary cells maintained the features of endocrine cells, up to 7 weeks in vitro. Secretory granules could be seen with electron microscopy, and cells contained immunocytochemically detectable levels of adenohypophyseal hormones. Significant levels of prolactin (PRL), growth hormone and luteinizing hormone were present in the culture media after several weeks in vitro and PRL release could be modulated by dopaminergic agonists or forskolin. The electrophysiological properties of pituitary cells were investigated with both intracellular and patch-clamp recordings after 2 to 7 weeks in vitro. Cellular resting membrane potentials were approximately -50 mV, and spontaneous or depolarization-induced action potentials were found in approximately 50% of cells. Records of voltage-dependent outward membrane currents showed that cells expressed functional voltage-gated channels. Cells remained responsive to hypothalamic neuropeptides, as shown by the outward membrane current triggered by thyrotropin-releasing hormone. Intracellularly injected Lucifer Yellow readily diffused between neighboring cells, suggesting the presence of gap junctions. These data confirm the viability of organotypic cultures of the anterior pituitary gland, and demonstrate that the characteristic properties of this excitable endocrine tissue are conserved. This neuroendocrine preparation is suitable for studying the mechanisms regulating cell-to-cell communication under conditions resembling the in vivo tissue organization.

Juvenile granulosa cell tumor of the ovary in infants: a clinicopathologic study of three cases and review of the literature

The clinical and pathological features of three cases of juvenile granulosa cell tumors occurring in infants were studied. Precocious pseudopuberty developed in two patients and acute abdominal symptoms related to the rupture of the tumor developed in one. Surgery was the only treatment in each case and no adjuvant therapy was delivered. No patient experienced relapse. Histological examination showed a predominantly diffuse pattern with prominent luteinization. Call-Exner bodies were absent. Two tumors had multilocular thin walled cysts containing large amounts of estradiol, the third one contained rudimentary microfollicles. The prognosis of juvenile granulosa cell tumors in infancy appears more favorable than those occurring in older patients. No case of tumor recurrence has been reported in infancy so far. Surgery appears to be the state-of-the-art treatment of these tumors and additional therapy (chemotherapy or radiotherapy) must be discussed with caution, even in advanced stages.

Continent cystostomy (Mitrofanoff's procedure) for neurogenic bladder in children and adolescent (56 cases: long-term results)

Between 1978 and 1991 we made a continent cystostomy according to Mitrofanoff's technique in 56 patients - children or adolescents - with a neurogenic bladder. We study the complications and the long-term results (follow-up ranging from 3 to 17 years - average 10 years). One patient died from a urological complication, another one died 2 years after from a neurological complication. Two patients were lost to follow-up after 3 years. Among the other patients 36 i.e. 64.3% have had urological complications. Analysis of these complications and their treatment demonstrates that most could now be avoided. At the present time the continent cystostomy with an appendicular or ureteral conduit is the safest and most comfortable way to treat the incontinence of wheel-chair bound patients who cannot or do not wish to use transurethral catheterisation.

Why are endocrine pituitary cells excitable?

Since 1975, endocrine pituitary cells have been known to be excitable neuronlike cells. Using powerful single-cell approaches, in particular the patch clamp electrophysiological recording technique and the monitoring of Ca(2+) with fluorescent probes, solid evidence has been provided in the last 10 years that intracellular Ca(2+) signals are produced by stimulators and inhibitors of secretion via the modulation of action potentials in isolated pituitary cells. As cytosolic Ca(2+) changes are thought to control numerous cellular functions (for example, secretion, protein synthesis, gene expression, and proliferation) over a long time scale-milliseconds to hours-it is now time to address the long-standing question of what functions would be physiologically controlled by electrical excitability in intact pituitary tissue.

Spontaneous and gonadotropin-releasing hormone-stimulated cytosolic calcium rises in individual goldfish gonadotrophs

The cytosolic free calcium concentration, [Ca2+]i, was monitored in single isolated goldfish gonadotrophs with the fluorescent probe Indo-1. It was found that goldfish gonadotrophs exhibit both spontaneous and secretagogue-induced [Ca2+]i rises. Spontaneous [Ca2+]i transients showed striking kinetic features and a sensitivity to external Ca2+ suggesting that they were the consequence of transient Ca2+ entries. Two kinetically distinct patterns of [Ca2+]i rises were generated in response to the two native forms of gonadotropin-releasing hormone (GnRH), salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II). In a part of the gonadotrophs, GnRHs triggered a plateau [Ca2+]i rise whereas in other responsive cells they induced a series of [Ca2+]i bursts, each consisting of grouped [Ca2+]i transients. Both plateau and burst [Ca2+]i response patterns were due to Ca2+ entry through plasma membrane Ca2+ channels, inasmuch as they were suppressed with external Ca2+ removal. No contribution of Ca2+ release from thapsigargin-sensitive stores was observed in either response pattern. While in mammalian gonadotrophs GnRH rises [Ca2+] by mostly acting on internal Ca2+ sequestering stores, our results show that GnRH-stimulated goldfish gonadotrophs rapidly increase Ca2+ entry to enhance their [Ca2+]i levels.

Artificial urinary sphincter implantation for neurogenic bladder: a multi-institutional study in 107 children

OBJECTIVES

To evaluate the outcome of implantation of the AMS 800 artificial urinary sphincter in children with neurogenic bladder.

PATIENTS AND METHODS

The records of 107 children (74 boys and 33 girls) treated for neurogenic urinary incontinence by implantation of the AMS 800 artificial sphincter between 1983 and 1993 were reviewed retrospectively. The underlying cause of incontinence in 92 patients was spina bifida, the mean age at implantation was 13.7 years and 30 patients had undergone previous bladder neck surgery. Implantation was carried out in combination with another surgical procedure in 24.3% of patients. The mean follow-up was 61 months (minimum 12).

RESULTS

The mean operational life of the sphincter was 56 months. No deaths occurred but removal of the artificial sphincter was necessary in 20 patients (19%). Surgical revision was not required in 44 patients (41%) but at least one revision was performed in 63 and more than one in 42. There were 21 mechanical failures, 40 surgical complications and 39 cases involving changes in the dynamics of bladder function. Of the 87 children (81%) in whom the device is still in place, 72 are completely continent (83%), 10 are slightly wet, and five are incontinent. The overall success rate was 77%.

CONCLUSIONS

The results emphasize that for successful implantation of an artificial urinary sphincter in children, the pre-operative bladder capacity must be sufficient and previous surgery should not have been performed on the bladder neck, the site of choice for implantation in children. Sphincterotomy is not always necessary in paediatric patients. Children and parents should be informed of the high complication rate and the need for long-term follow-up.

Direct observation of serotonin 5-HT3 receptor-induced increases in calcium levels in individual brain nerve terminals

Confocal microscopy was used to assess internal calcium level changes in response to presynaptic receptor activation in individual, isolated nerve terminals (synaptosomes) from rat corpus striatum, focusing, in particular, on the serotonin 5-HT3 receptor, a ligand-gated ion channel. The 5-HT3 receptor agonist-induced calcium level changes in individual synaptosomes were compared with responses evoked by K+ depolarization. Using the fluorescent dye fluo-3 to measure relative changes in internal free Ca2+ concentration ([Ca2+]i), K+-induced depolarization resulted in variable but rapid increases in apparent [Ca2+]i among the individual terminals, with some synaptosomes displaying large transient [Ca2+]i peaks of varying size (two- to 12-fold over basal levels) followed by an apparent plateau phase, whereas others displayed only a rise to a sustained plateau level of [Ca2+]i (two- to 2.5-fold over basal levels). Agonist activation of 5-HT3 receptors induced slow increases in [Ca2+]i (rise time, 15-20 s) in a subset (approximately 5%) of corpus striatal synaptosomes, with the increases (averaging 2.2-fold over basal) being dependent on Ca2+ entry and inhibited by millimolar external Mg2+. We conclude that significant increases in brain nerve terminal Ca2+, rivaling that found in response to excitation by depolarization but having distinct kinetic properties, can therefore result from the activation of presynaptic ligand-gated ion channels.