[Secondary surgeries in craniosynostosis and faciocraniosynostosis]. / Chirurgie secondaire des craniosténoses et faciocraniosténoses.

Secondary surgeries for single craniosynostosis surgeries are mainly esthetic refinements rather than functional indications. However, cranioplasties for bone defects correction or insufficient corrections may be undertaken. Management of syndromic craniosynostoses usually requires multiple surgical interventions, the sequence of which might vary per the genetic mutation. It is commonplace to start with posterior vault expansion before age 6 months, then treat cerebellar tonsillar herniation by the age of twelve months, and delay fronto-facial monobloc advancement until at least 18-24 months of age. Ventricular shunting is preferably avoided or delayed. Failure to respect these guidelines can significantly complicate the subsequent management. Primary fronto-orbital advancement or early facial osteotomy type Le Fort3, may compromise the subsequent fronto-facial monobloc advancement. However, this salvage secondary monobloc may be undertaken in some instances despite previous anterior osteotomies with a higher morbidity.

[Craniofacial strategy for syndromic craniosynostosis]. / Stratégie craniofaciale pour les faciocraniosténoses.

The complexity of treatment of faciocraniosynostosis justifies the treatment in a reference center for rare diseases. The growth disturbances in the skull and face being variable according to the type of mutation in the FGFr (Crouzon, Pfeiffer, Apert), the strategy is adapted to the phenotype according to the following principles: posterior expansion with or without distraction around 6 months to limit the descent of the cerebellum tonsils and to prevent the turricephalic development; fronto-facial monobloc advancement with internal distraction around the age of 18 months in case of severe exorbitism or breathing impairment. The dissociated strategy (fronto-orbital advancement first, followed by facial osteotomy of Le Fort 3 type). The growing evolution dictates the sequence of subsequent surgeries according to the monitoring of intracranial pressure by fundus examination and of the respiration by polysomnography. Le Fort 3 and transversal maxillary distraction may be repeated if necessary. Orthognathic surgery is almost always compulsory after the age of 14, before the aesthetic refinements which can be undertaken ultimately (rhinoplasty, genioplasty, canthopexies, fat grafting…).

Neoadjuvant chemotherapy: a new criterion for selection of candidate patients for surgery of low tumour burden metastases from malignant melanoma?

BACKGROUND: Surgery of limited metastatic lesions from malignant melanoma can achieve long-term remission and better survival than chemotherapy. Existing criteria for selection of candidate patients for this surgery do not seem sufficient to avoid useless excisions. OBJECTIVES: To test use of neoadjuvant chemotherapy as a new criterion in this setting. METHODS: All patients who underwent thoracic surgery for one or two lung metastases from melanoma during 1999-2007 were included in the study. Demographic and medical data were collected and analysed. Several possible prognostic factors were evaluated based on the overall survival curves. RESULTS: Thirteen patients were included in this retrospective study. All but two patients had no evidence of disease after surgery. Ten patients received neoadjuvant chemotherapy. Six responded (absence of progression) and four had progressive disease. Response to chemotherapy and no evidence of disease after surgery were predictive of long-term survival. CONCLUSIONS: Neoadjuvant chemotherapy can be considered as a new criterion for better selection of candidate patients for lung metastasis surgical resection. This would also avoid useless surgical procedures in rapidly progressive disease and give information on the chemosensibility of the metastatic disease. This study needs further confirmation, particularly with chemotherapy regimens that have demonstrated better objective responses.

Preparation of metal-ceramic composites by sonochemical synthesis of metallic nano-particles and in-situ decoration on ceramic powders.

Copper and nickel nanoparticles were synthesized using reducing agents in the presence of direct high energy ultra-sonication. The metallic nanoparticles were decorated on various ceramic substrates (e.g. α-Al2O3, and TiO2) leading to metal reinforced ceramics with up to 45% metallic content. Different parameters, such as the amount of precursor material or the substrate, as well as the intensity of ultrasound were examined, in order to evaluate the percentage of final metallic decoration on the composite materials. All products were characterized by means of Inductively Coupled Plasma Spectroscopy in order to investigate the loading with metallic particles. X-ray Diffraction and Scanning Electron Microscopy were also used for further sample characterization. Selected samples were examined using Transmission Electron Microscopy, while finally, some of the powders synthesized, were densified by means of Spark Plasma Sintering, followed by a SEM/EDX examination and an estimation of their porosity.

Solution structure of hpTX2, a toxin from Heteropoda venatoria spider that blocks Kv4.2 potassium channel.

HpTX2 is a toxin from the venom of Heteropoda venatoria spider that has been demonstrated to bind on Kv4.2 potassium channel. We have determined the solution structure of recombinant HpTX2 by use of conventional two-dimensional NMR techniques followed by distance-geometry and molecular dynamics. The calculated structure belongs to the Inhibitory Cystin Knot structural family that consists in a compact disulfide-bonded core, from which four loops emerge. A poorly defined two-stranded antiparallel beta-sheet (residues 20-23 and 25-28) is detected. Analysis of the electrostatic charge anisotropy allows us to propose a functional map of HpTX2 different from the one described for kappa-conotoxin PVIIA, but strongly related to the one of charybdotoxin. The orientation of the dipole moment of HpTX2 emerges through K27 which could therefore be the critical lysine residue. Close to this lysine are a second basic residue, R23, an aromatic cluster (F7, W25, W30) and an hydrophobic side chain (L24). The high density in aromatic side chains of the putative functional surface as well as the lack of an asparagine is proposed to be the structural basis of the specificity of HpTX2 toward Kv4.2 channel.

Genomic organization of the KTX2 gene, encoding a 'short' scorpion toxin active on K+ channels.

A single intron of 87 bp, close to the region encoding the C-terminal part of the signal peptide, was found in the gene of the 'short' scorpion toxin kaliotoxin 2 of Androctonus australis acting on various types of K+ channels. Its A+T content was particularly high (up to 86%). By walking and ligation-mediated PCR, the promoter sequences of the kaliotoxin 2 gene of Androctonus australis were studied. The transcription unit of the gene is 390 bp long. Consensus sequences were identified. The genes of 'short' scorpion toxins active on K+ channels are organized similarly to those of the 'long' scorpion toxins active on Na+ channels and not like those of structurally related insect defensins, which are intronless.

Evidence for a new class of scorpion toxins active against K+ channels.

cDNAs encoding novel long-chain scorpion toxins (64 amino acid residues, including only six cysteines) were isolated from cDNA libraries produced from the venom glands of the scorpions Androctonus australis from Old World and Tityus serrulatus from New World. The encoded peptides were very similar to a recently identified toxin from T. serrulatus, which is active against the voltage-sensitive 'delayed-rectifier' potassium channel, but they were completely different from the long-chain and short-chain scorpion toxins already characterised. However, there was some sequence similarity (42%) between these new toxins, Aa TX Kbeta and Ts TX Kbeta, and scorpion defensins purified from the hemolymph of Buthidae scorpions Leiurus quinquestriatus and A. australis. Thus, according to a multiple sequence alignment using CLUSTAL, these new toxins seem to be related to the scorpion defensins.

Influence of a NH2-terminal extension on the activity of KTX2, a K+ channel blocker purified from Androctonus australis scorpion venom.

A cDNA encoding a short polypeptide blocker of K+ channels, kaliotoxin 2 (KTX2), from the venom of the North African scorpion Androctonus australis was expressed in the periplasmic space of Escherichia coli. KTX2 was produced as a fusion protein with the maltose binding protein followed by the recognition site for factor Xa or enterokinase preceding the first amino acid residue of the toxin. The fully refolded recombinant KTX2 (rKTX2) was obtained (0.15-0.30 mg/l of culture) and was indistinguishable from the native toxin according to chemical and biological criteria. An N-extended analogue of KTX2 exhibiting three additional residues was also expressed. This analogue had 1000-fold less affinity for the 125I-kaliotoxin binding site on rat brain synaptosomes than KTX2. Conformational models of KTX2 and its mutant were designed by amino acid replacement using the structure of agitoxin 2 from Leiurus quinquestriatus as template, to try to understand the decrease in affinity for the receptor.

Characterization of a new peptide from Tityus serrulatus scorpion venom which is a ligand of the apamin-binding site.

A new ligand (Ts kappa) of the apamin binding site on rat brain synaptosomes (K0.5 = 300 pM) was purified and characterized from the venom of Tityus serrulatus. It is a polypeptide toxin of 35 amino acid residues, with three disulfide bridges. Its cDNA was amplified from a venom gland cDNA library and the nucleotide sequence determined. A model of Ts kappa was constructed by amino acid replacement using charybdotoxin structure as determined by 1H nuclear magnetic resonance as starting model.

A new class of scorpion toxin binding sites related to an A-type K+ channel: pharmacological characterization and localization in rat brain.

A new scorpion toxin (3751.8 Da) was isolated from the Buthus martensi venom, sequenced and chemically synthesized (sBmTX3). The A-type current of striatum neurons in culture completely disappeared when 1 microM sBmTX3 was applied (Kd=54 nM), whereas the sustained K+ current was unaffected. 125I-sBmTX3 specifically bound to rat brain synaptosomes (maximum binding=14 fmol x mg(-1) of protein, Kd=0.21 nM). A panel of toxins yet described as specific ligands for K+ channels were unable to compete with 125I-sBmTX3. A high density of 125I-sBmTX3 binding sites was found in the striatum, hippocampus, superior colliculus, and cerebellum in the adult rat brain.

The myth of scorpion suicide: are scorpions insensitive to their own venom?

The resistance of the scorpion Androctonus australis to its own venom, as well as to the venom of other species, was investigated. A comparison of the electrical and pharmacological properties of muscle and nerve fibres from Androctonus australis with those from the crayfish Procambarus clarkii enabled us to understand the lack of effect of scorpion venom (110-180 microg ml-1) and purified toxins, which are active on voltage-gated Na+ and K+ channels, Ca2+-activated K+ channels, on scorpion tissues. Voltage-clamp experiments showed that peptide K+ channel blockers from scorpion and snake have no effect on currents in muscle and nerve fibres from either scorpions or crayfish. The scorpion toxin kaliotoxin (KTX), a specific blocker of Kv1.1 and Kv1.3 K+ channels, had no effect on muscle fibres of A. australis (2 micromol l-1) or P. clarkii (400 nmol l-1). Similarly, charybdotoxin (ChTX) had no effect on the muscle fibres of A. australis (10 micromol l-1) or P. clarkii (200 nmol l-1) and neither did the snake toxin dendrotoxin (DTX) at concentrations of 100 nmol l-1 in A. australis and 200 nmol l-1 in P. clarkii. These three toxins (KTX, ChTX and DTX) did not block K+ currents recorded from nerve fibres in P. clarkii. The pharmacology of the K+ channels in these two arthropods did not conform to that previously described for K+ channels in other species. Current-clamp experiments clearly indicated that the venom of A. australis (50 microg ml-1) had no effect on the shape of the action potential recorded from nerve cord axons from A. australis. At a concentration of 50 microg ml-1, A. australis venom greatly prolonged the action potential in the crayfish giant axon. The absence of any effect of the anti-mammal -toxin AaH II (100 nmol l-1) and the anti-insect toxin AaH IT1 (100 nmol l-1) on scorpion nerve fibres revealed strong pharmacological differences between the voltage-gated Na+ channels of scorpion and crayfish. We conclude that the venom from A. australis is pharmacologically inactive on K+ channels and on voltage-sensitive Na+ channels from this scorpion.

Characterisation of the gene encoding the alpha-toxin Amm V from the scorpion Androctonus mauretanicus mauretanicus.

The full-length cDNA encoding the scorpion alpha-toxin Amm V was amplified from a cDNA library produced from the venom glands of the scorpion Androctonus mauretanicus mauretanicus from Morocco. We deduced the amino acid sequence of the encoded precursor protein and found that the mature toxin was similar to the previously characterised toxin. The genomic DNA sequence encoding the toxin was also amplified, subcloned and sequenced. This also led to the isolation of a new Amm V related-gene. Then, for the first time, we studied changes in the level of toxin mRNA synthesis over time.

Voice analysis to predict the psychological or physical state of a speaker.

A vocal message, apart from its semantic content, carries information on the psychological and physiological condition of the speaker. Physical fatigue and especially psychological stress are the pathological elements of the condition. The accepted term for the cause of these effects is the "workload." This article describes the main research carried out since the 1940's to measure the acoustic modifications of the voice brought about by a workload. It concludes by a critical analysis of the studies and a short description of the perspectives for research. Their results mainly concern astronauts and pilots involved in specific high-stress tasks and possible users of voice recognition systems. All the studies show an excellent approach to this field of research but deserve to be widened, deepened, and made more accurate to enable estimating the nature or level of reaction to a workload.

[Trial of halofantrine in the treatment of malaria attacks by Plasmodium falciparum in Dakar (Senegal)]. / Essai de l'halofantrine dans le traitement de l'accès palustre a Plasmodium falciparum a Dakar (Sénégal).

Halofantrine has been given to 14 children and 15 adults suffering from an acute attack of P. falciparum malaria and living in Dakar (Senegal) to a total dose of 24 mg/kg/body weight for the first group and 1,500 mg for the second in 3 times at 6-hourly intervals. This treatment has allowed the fever to clear in all cases within 36.3 +/- 19.9 hours and headache to disappear at D3 in 93.1% of cases. A reduction by 93.6% of the average parasite density which amounted before treatment to 27,710 trophozoites/mm3 of blood has been recorded from the day following the beginning of treatment and the parasite clearance obtained in all the patients of whom had chloroquine-resistant P. falciparum strains in mean time of 58.0 +/- 14.7 hours. In 3 cases (10.7%) a recrudescence of parasitemia has been noticed in D14. Only 1 of them was treated again with halofantrine which proved efficient from D2. The only adverse reactions have been nausea, vomiting, a slight diarrhoea and dizziness which affected only 13.8% of the patients. No abnormality has been noticed at a biological level. These results confirm the efficacy and good tolerance of halofantrine and allow to list it among the resource drugs used for the treatment of chloroquine-resistant P. falciparum malaria in our area.

Melatonin from cerebrospinal fluid but not from blood reaches sheep cerebral tissues under physiological conditions.

The pineal gland secretes melatonin (MLT) that circulates in the blood and cerebrospinal fluid (CSF). We provide data to support the hypothesis that, in sheep and possibly in humans, only the CSF MLT, and not the blood MLT, can provide most of MLT to the cerebral tissue in high concentrations, particularly in the periventricular area. The MLT content of sheep brain, our chosen animal model, was found in significant concentration gradients oriented from the ventricle (close to the CSF) to the cerebral tissue, with concentrations varying by a factor of 1-125. The highest concentrations were observed close to the ventricle wall, whereas the lowest concentrations were furthest from the ventricles (407.0 ± 71.5 pg/ml compared to 84.7 ± 5.2 pg/ml around the third ventricle). This concentration gradient was measured in brain tissue collected at mid-day and at the end of the night. Nocturnal concentrations were higher than daytime concentrations, reflecting the diurnal variation in the pineal gland. The concentration gradient was not detected when MLT was delivered to the brain via the bloodstream. The diffusion of MLT to cerebral tissues via CSF was supported by in vivo scintigraphy and autoradiography. 2-[(123)I]-MLT infused into the CSF quickly and efficiently diffused into the brain tissues, whereas [(123)I]-iodine (control) was mostly washed away by the CSF flow and [(123)I]-bovine serum albumin remained mostly in the CSF. Taken together, these data support a critical role of CSF in providing the brain with MLT.

The end of a myth: cloning and characterization of the ovine melatonin MT(2) receptor.

BACKGROUND AND PURPOSE: For many years, it was suspected that sheep expressed only one melatonin receptor (closely resembling MT(1) from other mammal species). Here we report the cloning of another melatonin receptor, MT(2), from sheep. EXPERIMENTAL APPROACH: Using a thermo-resistant reverse transcriptase and polymerase chain reaction primer set homologous to the bovine MT(2) mRNA sequence, we have cloned and characterized MT(2) receptors from sheep retina. KEY RESULTS: The ovine MT(2) receptor presents 96%, 72% and 67% identity with cattle, human and rat respectively. This MT(2) receptor stably expressed in CHO-K1 cells showed high-affinity 2[(125)I]-iodomelatonin binding (K(D)= 0.04 nM). The rank order of inhibition of 2[(125)I]-iodomelatonin binding by melatonin, 4-phenyl-2-propionamidotetralin and luzindole was similar to that exhibited by MT(2) receptors of other species (melatonin > 4-phenyl-2-propionamidotetralin > luzindole). However, its pharmacological profile was closer to that of rat, rather than human MT(2) receptors. Functionally, the ovine MT(2) receptors were coupled to G(i) proteins leading to inhibition of adenylyl cyclase, as the other melatonin receptors. In sheep brain, MT(2) mRNA was expressed in pars tuberalis, choroid plexus and retina, and moderately in mammillary bodies. Real-time polymerase chain reaction showed that in sheep pars tuberalis, premammillary hypothalamus and mammillary bodies, the temporal pattern of expression of MT(1) and MT(2) mRNA was not parallel in the three tissues. CONCLUSION AND IMPLICATIONS: Co-expression of MT(1) and MT(2) receptors in all analysed sheep brain tissues suggests that MT(2) receptors may participate in melatonin regulation of seasonal anovulatory activity in ewes by modulating MT(1) receptor action.

Melatonin activates brain dopaminergic systems in the eel with an inhibitory impact on reproductive function.

In the eel, a deficit in gonadotrophin-releasing hormone (GnRH) and a strong dopaminergic (DA) inhibition are responsible for the blockade of gonad development if silver eels are prevented from their reproductive migration. Environmental factors that eels encounter during their oceanic reproductive migration are thought to play an important role in the stimulation of eel pubertal development. We investigated the potential role of melatonin, a known mediator of the effects of external factors on reproductive function in vertebrates. We demonstrated that a long-term melatonin treatment increased brain tyrosine hydroxylase (TH, the rate limiting enzyme of DA synthesis) mRNA expression in a region-dependent way. Melatonin stimulated the dopaminergic system of the preoptic area, which is involved in the inhibitory control of gonadotrophin [luteinising hormone (LH) and follicle-stimulating hormone (FSH)] synthesis and release. Moreover, we showed that the increased TH expression appeared to be consistent with melatonin binding site distribution as shown by 2[(125)I]-melatonin labelling studies. On the other hand, melatonin had no effects on the two eel native forms of GnRH (mGnRH and cGnRH-II) mRNA expression. Concerning the pituitary-gonad axis, we showed that melatonin treatment decreased both gonadotrophin beta-subunit (LHbeta, FSHbeta) mRNA expression and reduced sexual steroid (11-ketotestosterone, oestradiol) plasma levels. This indicates that melatonin treatment had a negative effect on eel reproductive function. To our knowledge, the results of the present study provide the first evidence that melatonin enhances TH expression in specific brain regions in a non-mammalian species. By this mechanism melatonin could represent one pathway by which environmental factors could modulate reproductive function in the eel.

[Scorpion toxins]. / Les toxines de scorpion.

Scorpion are known to use a cocktail of toxins to immobilize their prey. So, their venoms constitute a complex mixture of polypeptides exhibiting different pharmacological activities. These polypeptides are small (between 30 and 70 amino acids long), basic and highly reticulated (3 or 4 disulfide bridges). They bind with very high affinities to specific targets, which are different ionic channels of excitable cells. Thus, they constitute usefull tools for the neurobiologist. The scorpion toxins can be divided into: 1) "long chain toxins" (60-70 amino acids residues cross-linked by 4 disulfide bridges) that affect exclusively voltage-dependent Na+ channels of excitable cells; 2) "short chain toxins" (30-40 amino acids residues cross-linked by 3 disulfide bridges) that block several types of K+ channels in different cells (not only potassium channels of excitable cells are affected by these toxins, but also those of erythrocytes or lymphocytes). Specificities or affinities of "long" and "short" chain toxins have been studied using structure-function relationships. Conformational analysis gave the three dimensional structures of an alpha, beta and anti-insect selective toxins. The molecules show a dense core of secondary structure, 2 1/2 turns of alpha-helice, and a short segment of anti-parallel beta-sheet, which exists in all known structures of scorpion toxins, irrespective of their size, sequence and function. From cDNA libraries, full-length cDNAs of about 370 nucleotides encoding precursors of these toxins have been isolated. Sequence analysis of these cDNAs show that the precursors contain signal peptides of about 20 amino acid residues. In addition, precursors of the toxins on mammalian Na+ have extensions at their COOH-terminal ends and have to be processed by specific exopeptidases to give the mature toxins. The cloning and sequencing of their genes revealed that they contain two exons and one intron near the end of the signal peptide sequence of the toxins precursors.

Critical care management of neurotrauma in children: new trends and perspectives.

Secondary brain lesions resulting from cerebral metabolic and hemodynamic reactions can be prevented by neurocritical care management. It must be initiated as soon as possible, ideally in a prehospital setting. Tracheal intubation, controlled ventilation and hemodynamic stabilization are the prerequisites. Beside intracranial and cerebral perfusion pressure, monitoring must evaluate the coupling between cerebral metabolic demand and blood flow. Jugular bulb oximetry is the most reliable approach to global cerebral coupling. Transcranial Doppler evaluates cerebral blood flow indirectly and noninvasively. Technological developments have led to local metabolic evaluation that does not yet have any clinical relevance. Therapeutic developments are more a new approach to the use of old drugs. Controlled hyperventilation, mannitol and, more recently, hypertonic saline solutions, used for restoring cerebral metabolic coupling, are the foundations of treatment. Thiopental, revisited as a vasoconstrictive agent, the "Lund" vasoconstrictive approach with anti-hypertensive drugs and cerebral vasoconstrictors, must be further evaluated in children, as must therapeutic hypothermia. Finally, what we probably need for the immediate future is a noninvasive and easily reproducible method of monitoring cerebral metabolic coupling that will allow precise therapeutic adaptation of multimodal therapy to the individual needs of the child.

Linear and nonlinear model of the human middle ear.

The measurement of the middle ear transfer function usually requires invasive methods. An equivalent analog equivalent model enables us to evaluate its characteristics without damaging any part of the ear. A linear and a nonlinear model of the middle ear have been developed to predict intracochlear pressure and the stapes volume velocity for various sound pressure levels (SPL). The linear model results have been compared with human eardrum impedance and middle ear transfer function data. The nonlinear phenomena due to the contraction of the stapedius muscle over 80 dB and to the stapes clipping displacement above 120 dB are represented by a set of variable electrical components. The model of the acoustic reflex is based on experimental observations. The study of the annular ligament behavior was performed on cats and extrapolated to humans with some hypothetical restrictions. These approximations provide information on the middle ear transfer function and enable us to better understand the nonlinear middle ear mechanisms in an intense acoustic field.