Time-resolved tympanal mechanics of the locust

A salient characteristic of most auditory systems is their capacity to analyse the frequency of sound. Little is known about how such analysis is performed across the diversity of auditory systems found in animals, and especially in insects. In locusts, frequency analysis is primarily mechanical, based on vibrational waves travelling across the tympanal membrane. Different acoustic frequencies generate travelling waves that direct vibrations to distinct tympanal locations, where distinct groups of correspondingly tuned mechanosensory neurons attach. Measuring the mechanical tympanal response, for the first time, to acoustic impulses in the time domain, nanometre-range vibrational waves are characterized with high spatial and temporal resolutions. Conventional Fourier analysis is also used to characterize the response in the frequency domain. Altogether these results show that travelling waves originate from a particular tympanal location and travel across the membrane to generate oscillations in the exact region where mechanosensory neurons attach. Notably, travelling waves are unidirectional; no strong back reflection or wave resonance could be observed across the membrane. These results constitute a key step in understanding tympanal mechanics in general, and in insects in particular, but also in our knowledge of the vibrational behaviour of anisotropic media.

A series of five adult cases of respiratory syncytial virus-related acute respiratory distress syndrome

Respiratory syncytial virus is a common cause of respiratory tract disease in children, predominantly presenting with mild symptoms. We present five cases of respiratory syncytial virus infection of the lower respiratory tract in immunocompromised adults suffering from severe respiratory insufficiency leading to bilateral pneumonia and fulfilling the criteria for acute respiratory distress syndrome. Respiratory syncytial virus was cultured as the only pathogen in the bronchoalveolar lavage fluid in four of these patients. Despite various therapeutic interventions, only one patient survived. Respiratory syncytial virus was implicated as a direct cause of respiratory failure. Respiratory syncytial virus may be an underestimated cause of severe respiratory failure and acute respiratory distress syndrome in the immunocompromised adult admitted to the intensive care unit.

Relationship between lignin structure and delignification degree in Pinus pinaster kraft pulps

This study examines the structure of residual and dissolved lignins from Pinus pinaster pulps obtained at different degrees of delignification by laboratory conventional kraft pulping. The cooking H factor was varied from 85 to 8049. The residual and dissolved lignin samples were characterised by elemental analysis, residual carbohydrate content, permanganate oxidation and 13C NMR spectroscopy. The reflectance factor of the pulps was also determined in order to tentatively correlate the delignification degree and residual lignin structure with the pulp colour. The obtained results confirmed that the delignification degree increases the condensation of the lignin structure, which might have an influence upon the observed increased pulp colour. The lack of selectivity of kraft pulping process in the case of more delignified pulps was also shown.

[Esophageal achalasia, sleep disorders and chorea in a tauopathy without ophthalmoplegia, parkinsonian syndrome, nor dementia (progressive supranuclear palsy?): clinicopathological study]

CONTEXT

Progressive supranuclear palsy (PSP) is classically characterized by supranuclear ophthalmoplegia, paroxysmal imbalance with backward falling, axial dystonia, rigidity, pseudobulbar palsy and cognitive dysfunction. However, incomplete or atypical clinical presentation has been previously reported, but in all these cases, the patients had at least one of the main clinical features of the disease (ophthalmoplegia, parkinsonian syndrome or cognitive dysfunction).

CASE REPORT

A 60-year-old woman presented with nocturnal agitation and choreiform movements. A few months later she developed severe swallowing disorders, caused by achalasia of the upper esophageal sphincter, and responsible for recurrent acute respiratory distress and pneumonia, prevailing to tracheotomy and gastrostomy. She died suddenly two years after the onset of the symptoms.

RESULTS

Postmortem examination of brain revealed a tauopathy, with deposition of abnormal phosphorylated tau in threads and in coiled-shaped as well as globose tangles in the brainstem, subthalamic nuclei and hippocampus. Nuclei of the medulla, including the vagus/solitarius complex and the region of the nucleus ambiguous were especially rich in tau positive inclusions. Ultrastructural analysis of globoid-shaped tangles in the brainstem revealed the presence of straight and paired helicoidal filaments compatible with a PSP.

CONCLUSIONS

This case contributes to improve knowledge of the clinical phenotypic range of PSP. In this case, the neuropathological lesions accounted for most of the symptoms. However, the early death of the patient was probably related to the particular distribution of the neuropathological lesions. This case suggests that the initial neuropathological changes in PSP is located in the dorsal brainstem.

Nanomechanical and electrical characterization of a new cellular electret sensor-actuator

Electrically charged cellular polymers are known to display pseudo-piezoelectric effects that endow them with interesting mechano-electrical characteristics. When a film of such a polymer is compressed, charge is generated across its thickness, and conversely, applying an oscillatory or static potential elicits mechanical motions. This dual sensor-actuator behaviour can be embedded in one material and presents distinct advantages of functional integration. A novel electroactive foam is presented here that embeds such a sensor-actuator function. The foam has a sensitivity constant (d(33)) of 330 pC N(-1). Interestingly, the resonant behaviour of the cellular film can be altered by variation in the DC offset across the material. Such adaptive capacity could be of great advantage for tuning polymer-based mechanical devices to be either efficient sound radiators and mechanical actuators, or sensitive and coherent sensors. Possible applications in microfluidics are also discussed.

Necrotizing gastritis due to Bacillus cereus in an immunocompromised patient

Bacillus cereus is increasingly being acknowledged as a serious bacterial pathogen in immunocompromised patients. We present a case of acute necrotizing gastritis caused by B. cereus in a 37-year-old woman with acute myeloblastic leukemia, who recovered following total parenteral nutrition and treatment with imipenem and vancomycin. B. cereus was isolated from gastric mucosa and blood cultures. Up to now, no case of acute necrotizing gastritis due to this organism has been reported.

Mechanics of a 'simple' ear: tympanal vibrations in noctuid moths

Anatomically, the ears of moths are considered to be among the simplest ears found in animals. Microscanning laser vibrometry was used to examine the surface vibrations of the entire tympanal region of the ears of the noctuid moths Agrotis exclamationis, Noctua pronuba, Xestia c-nigrum and Xestia triangulum. During stimulation with ultrasound at intensities known to activate receptor neurones, the tympanum vibrates with maximum deflection amplitudes at the location where the receptor cells attach. In the reportedly heterogeneous tympana of noctuid moths, this attachment site is an opaque zone that is surrounded by a transparent, thinner cuticular region. In response to sound pressure, this region moves relatively little compared with the opaque zone. Thus, the deflections of the moth tympanic membrane are not those of a simple circular drum. The acoustic sensitivity of the ear of N. pronuba, as measured on the attachment site, is 100+/-14 nm Pa(-1) (N=10), corresponding to tympanal motion of a mere 200 pm at sound pressure levels near the neural threshold.

The effect of landfill leachate composition on organics and nitrogen removal in an activated sludge system with bentonite additive

A pre-denitrification activated sludge system (AS) without internal recycle was used in lab-scale studies of landfill leachate treatment. A bentonite supplement at a ratio of 1:4 (mineral : biomass) was used to ensure high sludge settling levels and to serve as a micro-organisms carrier. The system was operated within different parameters such as hydraulic retention time (HRT), ammonia loading rate (ALR) or external recycle ratio, which was adapted to treat varying leachate concentrations of COD and ammonia, ranging from 1020 to 2680 mgO(2)l(-1) and 400-890 mgNH(4)-Nl(-1) respectively. The nitrification was complete and ammonia oxidation reached 99%; this was obtained while the ALR did not exceed 0.09 g NH(4)(+)-Ng(-1)MLVSS d(-1) and HRT was not lower than 1 day (in the aeration reactor). The performance of denitrification was successfully improved by controlling the external recycle rate, when the BOD(5)/N ratio in the raw leachate was 4.1. Consequently, N-removal of up to 80% was achieved. A 10-fold decrease in the denitrification rate was obtained at a BOD(5)/N ratio of 0.5. The efficiency of COD removal varied significantly from 36% to 84%. The positive effect of bentonite addition was determined and is discussed based on preliminary studies. The experiments were carried out in fill-and-draw activated sludge with bentonite; the biomass ratio was 1:2. The activated sludge with bentonite was fed with a synthetic high ammonia and organic-free medium.

Association d'une encéphalite à herpès virus 6 et d'un syndrome d'hypersensibilité médicamenteuse au triméthoprime-sulfaméthoxazole

INTRODUCTION

Human herpesvirus 6 (HHV-6), the causative agent of the common exanthem subitum, is a known cause of central nervous system infection in immunocompromised patients. It has been suggested that HHV-6 participate in the development of drug-induced hypersensitivity syndrome.

CASE REPORT

We reported a case of HHV-6 encephalitis associated with hypersensitivity syndrome induced by trimethoprim-sulfamethoxazole in a 72-year-old HIV-negative woman.

DISCUSSION

Our case confirmed that reactivation of HHV-6 infection may contribute to the development of the hypersensitivity syndrome.

Aspects cliniques, microbiologiques et thérapeutiques des infections à Nocardia sp. au centre hospitalier universitaire de Bordeaux entre 1993 et 2003

OBJECTIVE

Our goal was to describe the epidemiological, clinical, and microbiological characteristics of nocardiosis in the Bordeaux teaching hospital, between January 1, 1993 and December 31, 2003.

DESIGNS

The retrospective study included patients examined between January 1, 1993 and December 31, 2003 in whom a Nocardia bacterium had been identified from a biological sample.

RESULTS

Twenty-four out of 30 Nocardia sp. strains identified during the study period were classified as colonizing strains. 19 patients presented with risk factors for nocardiosis. Nocardia asteroïdes were found in 22 samples, mainly from pulmonary samples. 11 cases of infection due to Nocardia sp. were reported during the study period. Immunosuppression was reported in 7 cases. The clinical forms were not specific. The species incriminated belonged to the N. asteroïdes complex in 8 cases. Treatment consisted in a combination of 2 or 3 molecules including cotrimoxazole for an average duration of 9 months. 9 patients recovered.

CONCLUSIONS

The variability of clinical presentation and the lack of standard identification methods delayed the diagnostic. The treatment is not well defined. Clinical strains should be reported to the reference laboratory and prospective studies are necessary.

Évaluation des troubles de la parole et de la déglutition chez les patients atteints de sclérose latérale amyotrophique

Swallowing and speech disorders are the dramatic consequences of bulbar and pseudo-bulbar syndrome in ALS. Evaluation is necessary to guide speech therapy and to measure the effects of treatment. This article revues the different examinations used to assess bulbar and pseudobulbar involvement in an ALS patient: oromotor assessment, evaluation of the functions with self assessment, perceptive and objective evaluation of speech disorders, fiberoptic endoscopic evaluation of dysphagia (FEES) and videofluoroscopy.

Loading dose of vancomycin in critically ill patients: 15mg/kg is a better choice than 500mg

Delays in antimicrobial therapy in high-risk patients with infection may have deleterious effects on clinical outcomes. Therefore, appropriate treatment must be initiated promptly. The objective of this prospective study was to determine the better loading dose of vancomycin in critically ill patients with suspected Gram-positive infections. Two groups of patients were studied successively: Group A, loading dose of 500 mg; and Group B, loading dose of 15 mg/kg. The mean post-loading dose serum vancomycin concentration was significantly higher in Group B than in Group A (19.1 +/- 7.4 mg/L versus 10.4 +/- 2.7 mg/L; P < 0.001), without producing toxic peak levels. Clinical cure rates were significantly different for infected patients in Group B compared with Group A: 93% (14 of 15 patients) versus 56% (10 of 18 patients), respectively. However, the proportion of patients surviving to Intensive Care Unit discharge was similar. Because vancomycin is believed to achieve maximum killing at concentrations in serum of four to five times the minimum inhibitory concentration for the infecting organism, our results suggest that the 15 mg/kg loading dose should be preferred.

Leachate detoxification by combination of biological and TiO2-photocatalytic processes

Landfill leachates are a problematic wastewater due to their variable concentration, volume changing in time and presence of refractory and hazardous components. In this paper, the results of a new approach to photocatalysis assisted by biological process for the detoxification of stabilised landfill leachate are presented. The biologically pre-treated leachate still contained a significant amount of non-biodegradable COD and TOC amounting to 500 and 200 mg/L, respectively. The 300 min of photocatalytic treatment (UVC/TiO2) brought about a significant decrease in more than 80% refractory organics remaining in leachate. The effect of pH and catalyst loading on mineralisation, colour removal rate and biodegradability (BOD/COD) improvement in the photoreactor were discussed. The bio-accessibility of formed photocatalytic oxidation intermediates was confirmed by oxygen uptake rate (OUR) measurements. Consequently, a part of COD was successfully removed in post-biological treatment.