ATP-dependent conformational dynamics in a photoactivated adenylate cyclase revealed by fluorescence spectroscopy and small-angle X-ray scattering.

Structural insights into the photoactivated adenylate cyclases can be used to develop new ways of controlling cellular cyclic adenosine monophosphate (cAMP) levels for optogenetic and other applications. In this work, we use an integrative approach that combines biophysical and structural biology methods to provide insight on the interaction of adenosine triphosphate (ATP) with the dark-adapted state of the photoactivated adenylate cyclase from the cyanobacterium Oscillatoria acuminata (OaPAC). A moderate affinity of the nucleotide for the enzyme was calculated and the thermodynamic parameters of the interaction have been obtained. Stopped-flow fluorescence spectroscopy and small-angle solution scattering have revealed significant conformational changes in the enzyme, presumably in the adenylate cyclase (AC) domain during the allosteric mechanism of ATP binding to OaPAC with small and large-scale movements observed to the best of our knowledge for the first time in the enzyme in solution upon ATP binding. These results are in line with previously reported drastic conformational changes taking place in several class III AC domains upon nucleotide binding.

On the implementation of computed laminography using synchrotron radiation.

Hard x rays from a synchrotron source are used in this implementation of computed laminography for three-dimensional (3D) imaging of flat, laterally extended objects. Due to outstanding properties of synchrotron light, high spatial resolution down to the micrometer scale can be attained, even for specimens having lateral dimensions of several decimeters. Operating either with a monochromatic or with a white synchrotron beam, the method can be optimized to attain high sensitivity or considerable inspection throughput in synchrotron user and small-batch industrial experiments. The article describes the details of experimental setups, alignment procedures, and the underlying reconstruction principles. Imaging of interconnections in flip-chip and wire-bonded devices illustrates the peculiarities of the method compared to its alternatives and demonstrates the wide application potential for the 3D inspection and quality assessment in microsystem technology.

[Recurrent giant cystic vestibular schwannomas: role of cystoperitoneal shunt]. / Schwannomes vestibulaires kystiques géants: intérêt du drainage kystopéritonéal.

INTRODUCTION: Surgical removal of giant cystic vestibular schwannomas is difficult because of adherences between the cyst membrane, brainstem, and the VII-VIII nerve complex. The recurrence of the cyst is frequent and requires reoperation. The aim of this study was to analyze the role of the palliative cystoperitoneal shunt in giant cystic vestibular schwannomas. MATERIALS AND METHODS: Eighty-eight patients with a diagnosis of stage III or IV vestibular schwannoma were managed surgically from January 2000 to December 2005 in our department. Six schwannomas were deemed to be cystic according to the following criteria: a voluminous cystic component with mass effect causing symptoms as well as radiological and intraoperative identification of cystic elements. RESULTS: Complete tumor removal was achieved in two patients. After a follow-up of 5 and 7 years, these patients were asymptomatic. In four cases, we performed cyst drainage. For three patients, we implanted a permanent cystoperitoneal shunt. These patients were asymptomatic with a mean follow-up of 19.7 months. CONCLUSIONS: The cystoperitoneal shunt with no valve is a valid palliative surgical solution to remove brain stem compression. Neuronavigation allows proper positioning of the drain and secures the procedure.

How measurements of rate coefficients at low temperature increase the predictivity of photochemical models of Titan's atmosphere.

The predictivity of photochemical models of Titan's atmosphere depends strongly on the precision and accuracy of reaction rates. For many reactions, large uncertainty results from the extrapolation of rate laws to low temperatures. A few reactions have been measured directly at temperatures relevant to Titan's atmosphere. In the present study, we observed the consequences of the reduced uncertainty attributed to these reactions. The global predictivity of the model was improved, i.e., most species are predicted with lower uncertainty factors. Nevertheless, high uncertainty factors are still observed, and a new list of key reactions has been established.

[Extradural spinal meningioma: case report]. / Méningiome rachidien extradural. A propos d'un cas et revue de la littérature.

OBJECTIVES: We report a case of purely extradural spinal meningioma and discuss the potential pitfalls in differential diagnosis. BACKGROUND: Spinal meningiomas account for 20-30% of all spinal neoplasms. Epidural meningiomas are infrequent intraspinal tumors that can be easily confused with malignant neoplasms or spinal schwannomas. CASE: A 62-year-old man with a previous history of malignant disease presented with back pain and weakness of the lower limbs. Magnetic resonance imaging revealed a well-enhanced T4 intraspinal lesion. The intraoperative histological examination showed a meningioma (confirmed by postoperative examination). Opening the dura mater confirmed the purely epidural location of the lesion. The postoperative course was uneventful with no recurrence 12 months after surgery. CONCLUSION: Purely extradural spinal meningiomas can mimic metastatic tumors or schwannomas. Intraoperative histology is mandatory for optimal surgical decision making.

[Surgical management of synovial cyst of the lumbar spine: retrospective study of 52 patients]. / Prise en charge chirurgicale des kystes synoviaux lombaires: étude rétrospective concernant 52 patients.

PURPOSE OF THE STUDY: Lumbar synovial cysts are an uncommon cause of radiculopathy, low back pain and neurogenic claudication. We report a retrospective analysis of the clinical presentation, radiological studies, operative findings and outcome in 52 patients surgically treated for symptomatic lumbar synovial cysts. MATERIAL AND METHODS: Retrospective data from 52 consecutive patients treated from January 1996 to February 2006 were analyzed. We studied the clinical symptoms, diagnostic methods and radiological findings in all patients, reviewed the types of conservative therapy applied, the surgical findings and techniques, as well as the immediate and long-term results. Surgical outcomes were evaluated according to the Friedberg scale. RESULTS: There were 35 women and 17 men with an average age of 63.2 years (range 36-84 years). The most common symptoms were radiculopathy (65,4%) and neurogenic multiroot claudication (34,6%). Forty-seven patients had back pain and 22 paresthesia. Preoperative neurological examination demonstrated motor weakness (5.7%), sensory loss (7.6%). The radiological work-up consisted in CT-scan and/or MRI for all patients. The correct preoperative diagnosis was established in 44 patients. A total of 56 cysts were found. Five patients had bilateral cysts. The L4-L5 level was affected in 66%. Total resection of the synovial cyst was possible for 46 patients. No fusion was performed as a first line procedure. However, subsequent fusion was necessary in one patient who developed delayed symptomatic spondylolisthesis. Mean follow up period was 14 months ranging from six to 24 months. Three recurrences occurred during the follow-up period. Functional outcome was excellent in 61.6%, good in 34.6% and poor in 3.8%. CONCLUSION: Surgery should be proposed when synovial cysts fail to respond to conservative therapy. Recurrence and surgical complication rates are low. The usefulness of systematic fusion procedure is questionable.

Solvation dynamics of electron produced by two-photon ionization of liquid polyols. III. Glycerol.

The solvation dynamics of excess electrons in glycerol have been measured by the pump-probe femtosecond laser technique at 333 K. The electrons are produced by two-photon absorption at 263 nm. The change in the induced absorbance is followed up to 450 ps in the spectral range from 440 to 720 nm. The transient signals of electron solvation have been analyzed by two kinetic models: a stepwise mechanism and a continuous relaxation model, using a Bayesian data analysis method. The results are compared with those previously published for ethylene glycol (J. Phys. Chem. A 2006, 110, 175) and for propanediols (J. Phys. Chem. A 2007, 111, 4902). From the comparison, it is pointed out that solvation dynamics in glycerol is very fast despite its high viscosity. This is interpreted as the existence of efficient traps for the electrons in glycerol with low potential energy. The small shift of the absorption band of the excess electron indicates that the potential of these traps is very close to that corresponding to the fully solvated electron.

Solvation dynamics of electron produced by two-photon ionization of liquid polyols. II. Propanediols.

Temporal evolution of transient absorption spectra of electrons produced by two-photon ionization of two isomers, propane-1,2-diol (12PD) and propane-1,3-diol (13PD), with 263 nm femtosecond laser pulses has been studied on picosecond time scale. The two-photon absorption coefficients of 12PD and 13PD at 263 nm were determined to be beta = (2.0 +/- 0.3) x 10(-11) and (2.4 +/- 0.3) x 10(-11) m W(-1), respectively. Time-resolved absorption spectra ranging from 440 to 720 nm have been measured, showing a blue shift for the first tens of picoseconds for both solvents. However, the observed solvation dynamics of electron appears faster in 13PD than in 12PD. The transient signals of electron solvation have then been reconstructed with different models (stepwise mechanism or continuous relaxation model) using a Bayesian data analysis method. Results are discussed, compared with those previously obtained in ethylene glycol (J. Phys. Chem. A 2006, 110, 1705) and corroborate the interpretation, according to which the solvation of electrons is mainly governed by continuous solvent molecular motions.

[Spinal cord compression by arachnoid cysts]. / Compression médullaire par kystes arachnoïdiens.

Spinal arachnoid cysts are considered to be rare entities, intradural locations are even less common. We report two cases of patients (two women aged 77- and 21-year-old) who presented spinal cord compression by intradural arachnoid cysts. For the second patient, repeated surgical procedures were necessary to improve the neurological status. After presenting the case reports, we expose the pathophysiological mechanisms and clinical features, and the surgical difficulties of treating this rare cause of spinal cord compression.

High-throughput sample handling and data collection at synchrotrons: embedding the ESRF into the high-throughput gene-to-structure pipeline.

An automatic data-collection system has been implemented and installed on seven insertion-device beamlines and a bending-magnet beamline at the ESRF (European Synchrotron Radiation Facility) as part of the SPINE (Structural Proteomics In Europe) development of an automated structure-determination pipeline. The system allows remote interaction with beamline-control systems and automatic sample mounting, alignment, characterization, data collection and processing. Reports of all actions taken are available for inspection via database modules and web services.

Solvation dynamics of the electron produced by two-photon ionization of liquid polyols. 1. Ethylene glycol.

Solvated electrons have been produced in ethylene glycol by two-photon ionization of the solvent with 263 nm femtosecond laser pulses. The two-photon absorption coefficient of ethylene glycol at 263 nm is determined to be beta = (2.1 +/- 0.2) x 10(-11) m W(-1). The dynamics of electron solvation in ethylene glycol has been studied by pump-probe transient absorption spectroscopy. So, time-resolved absorption spectra ranging from 430 to 710 nm have been measured. A blue shift of the spectra is observed for the first tens of picoseconds. Using the Bayesian data analysis method, the observed solvation dynamics are reconstructed with different models: stepwise mechanisms, continuous relaxation models, or combinations of stepwise and continuous relaxation. Comparison between models is in favor of continuous relaxation, which is mainly governed by solvent molecular motions.

[Thoracic and thoraco-lumbar discs herniations: diagnosis and therapeutic management]. / Les hernies discales thoraciques et thoraco-lombaires: prise en charge diagnostique et therapeutique.

Summary Management of symptomatic thoracic disc hemiations is difficult because of their polymorphic symptomatology and hardness to join the intervertebral thoracic disc surgically. The objective of this study was first to show the difficult diagnosis of these discal herniations and their posterior approach particularities; secondly, to analyse our results and compare them with those of the literature. This retrospective study analyses a four patients series operated between January 1997 and march 2003 using intraoperative somatosensory evoked potentials. All of them had before surgical management, a lumbar Xray or a MRI. The average postoperative follow-up was seven months. All patients were males with a mean age of 39.5 years old (extremes: 22-59). They had systematisation of their lumboradiculalgia, leading to an average delayed diagnosis of 10 months. The disc herniation was paramedian in three cases, median in one,. It was in T10-T11 in one case, in T11-T12 in two and in T12-L1 in one. All the patients were operated on with a posterior approach, recording the intraoperative somatosensory evoked potentials. Disc herniation was resected in three cases. Functional results were satisfactory (no pains for three patients) in the follow-up period of seven months. Every patient presenting with an atypical lumboradiculalgia must have a spine MRI to diagnose the symptomatic thoracic disc herniation. Surgery has good results if technical details are used respecting the threatened spinal cord.

[Neuronavigation in third ventricle tumors]. / Tumeurs du troisième ventricule et neuronavigation.

The authors present the results of neuronavigation as a help to open neurosurgery for the tumors of the third ventricle. From January, 1995 to August, 1999, six image-guided surgical procedures were performed to remove third ventricle lesions : 4 colloïd cysts, 1 ependymoma, and 1 craniopharyngioma. The operative approach was transcortical in 5 cases, and transcallosal in 1 case. The use of neuronavigation allows a decrease of the surgical trauma during the surgical approach. The procedure secures the neurosurgeon in the choice and execution of his pathway to the target. It becomes however less accurate after opening the ventricle, because of the brainshift induced by the loss of cerebrospinal fluid becomes important. Nevertheless, neuronavigation is useful in the surgery of the third ventricle, especially if it is used with neuroendoscopy.

Phase imaging using highly coherent X-rays: radiography, tomography, diffraction topography.

Several hard X-rays imaging techniques greatly benefit from the coherence of the beams delivered by the modern synchrotron radiation sources. This is illustrated with examples recorded on the 'long' (145 m) ID19 'imaging' beamline of the ESRF. Phase imaging is directly related to the small angular size of the source as seen from one point of the sample ('effective divergence' approximately microradians). When using the ;propagation' technique, phase radiography and tomography are instrumentally very simple. They are often used in the 'edge detection' regime, where the jumps of density are clearly observed. The in situ damage assessment of micro-heterogeneous materials is one example of the many applications. Recently a more quantitative approach has been developed, which provides a three-dimensional density mapping of the sample ('holotomography'). The combination of diffraction topography and phase-contrast imaging constitutes a powerful tool. The observation of holes of discrete sizes in quasicrystals, and the investigation of poled ferroelectric materials, result from this combination.

[Simultaneous hepatic cholangiocarcinoma and bone fibrosarcoma 45 years after ingestion of Thorotrast]. / Cholangiocarcinome hépatique et fibrosarcome osseux synchrones 45 ans après injection de Thorotrast.

This case of a 63 year old man reports the simultaneous development of hepatic cholangiocarcinoma and fibrosarcoma of the sacrum 45 years after the systemic injection of Thorotrast. The characteristic radiologic aspect was an important criteria for diagnosis. Biopsies have confirmed the histology of both tumors. We describe the way to thorotrastosis diagnosis and characteristic malignant tumors, especially cholangiocarcinoma, induced by Thorotrast.

Colonization of burns and the duration of hospital stay of severely burned patients.

In a retrospective study the influence of several factors on the length of hospital stay of severely burned patients (at least 24% total body surface area) has been investigated. The influence of these factors was studied by means of the Cox model survival analysis with time-varying covariates. Seventy-one patients were included in this study. The mean age was 32 years (range 1-82 years), the mean total body surface area burned 40% (range 24-80%) and the mean full-thickness area burned 32% (range 10-70%). The length of hospital stay was positively correlated with the extent of the burned area and with the age of the patient. Wound colonization with Enterobacteriaceae or with a combination of Pseudomonas spp. and Staphylococcus aureus was also associated with a prolonged stay in hospital.

[Laser microsurgery of meningioma. An analysis of a consecutive series of 164 cases treated surgically by using different lasers]. / La microchirurgie au laser des méningiomes. Analyse d'une série consécutive de 164 cas opérés avec différents lasers.

Over a six years period, 224 laser procedures were performed in our clinic, of these 164 (72%) involved meningiomas of various intracranial and spinal locations; 82 (50%) tumors were located in the posterior fossa, 36 (32%) were suprasellar or parasellar meningiomas: a carbon dioxide laser was used in 56 cases, a double wave length YAG laser in 101 cases, and recently a simultaneous Nd YAG and CO2 combolaser in 7 cases. Complete tumor removal was accomplished in 83% of cases and overall mortality was 3%. We think that microscope guided laser techniques represents a significant advancement in the ability to remove deep situated meningiomas that might prove difficult to extirpate by conventional microsurgery. The advantages of these methods include: 1. reduced brain retraction; 2. the ability to operate with smaller and different exposures; 3. a reduced amount of mechanical manipulation by vaporizing in first the dural attachment; 4. improved operative precision and 5. decreased intra operative blood loss.

[Preservation of auditory function in the excision of acoustic neuroma]. / Conservation de l'audition dans l'exérèse des neurinomes de l'acoustique.

Selection criteria for the preservation of auditory function during excision of acoustic neurinoma have been defined for a long time, and the means for a successful achievement of such a goal are widely known. Recruitment of special patients, for whom maintenance of an even deeply altered hearing capacity constitutes a requisite for continuation of professional work has lead us to extend indications for the pre- and retrosigmoid approaches recommended by J.M. Sterkers. The authors present a series of 16 patients, in which a single case of cophosis was deplored.

[hCG and its subunits as tumor markers]. / hCG et ses sous-unités comme marqueurs tumoraux.

hCG is known to be produced by trophoblastic cells as well as by many normal tissues and malignancies. hCG is considered as a reliable marker for gonadal and extra gonadal choriocarcinomas; moreover it has been evidenced by immunohistochemical techniques in other malignancies. In this study, hCG and/or its alpha and beta subunits were detected in 73 males. Intact hCG was detected in 48 patients with gonadal tumors (n = 37) or extragonadal malignancies (n = 11), with or without free alpha or beta subunits. In the other 25 patients, native hCG was not detected but there were significant amounts of free beta subunit in 8 germ cells tumors and 17 extragonadal tumors. The production of free beta chains is correlated with a severe evolution in extragonadal tumors. hCG should be considered as a good marker for many tumors, but it is absolutely necessary to evaluate intact hCG as well as free beta chains.