Evaluation of hydrogen peroxide and ozone residue levels on N95 masks following chemical decontamination.

BACKGROUND: Hydrogen peroxide and ozone have been used as chemical decontamination agents for N95 masks during supply shortages. If left behind on the masks, the residues of both chemicals represent a potential health hazard by skin contact and respiratory exposure. AIM: Characterization of hydrogen peroxide and ozone residues on mask surfaces after chemical decontamination. METHODS: Various N95 masks were decontaminated using two commercial systems employing either aerosol spray or vaporization of hydrogen peroxide in the presence of ozone. Following the decontamination, the masks were aired out to eliminate moisture and potential chemical residues. The residual hydrogen peroxide and ozone were monitored in the gas phase above the mask surface, and hydrogen peroxide residue directly on mask surfaces using a colorimetric assay. FINDINGS: After decontamination, hydrogen peroxide and ozone were detectable in the gas phase in the vicinity of masks even after 5 h of aeration. Hydrogen peroxide was also detected on all studied masks, and levels up to 56 mg per mask were observed after 0.5 h of aeration. All residues gradually decreased with aeration, likely due to decomposition and vaporization. CONCLUSION: Hydrogen peroxide and ozone were present on N95 masks after decontamination. With appropriate aeration, the gaseous residue levels in the vicinity of the masks decreased to permissible levels as defined by the US Occupational Safety and Health Administration. Reliable assays to monitor these residues are necessary to ensure the safety of the mask users.

Microsurgical anatomy of the fourth ventricle.

Anatomical description of the fourth ventricle is essential for an accurate understanding of its related tumoral pathologies and surgical approach respecting cerebellar and brainstem structures. Numerous cadaver pictures illustrate this chapter which contains V4 floor and roof description and its vascularization.

Microvascularization of the human central and peripheral nervous system: A new microcomputed tomography method.

Microcomputed X-ray tomography (microCT), developed since the late 1990s, is a miniaturized version of the tomographs used daily in medical imaging. It produces vascular images that are different from those obtained by microradiography, in particular by facilitating the vision in space, thus understanding microvascularisation. The anatomical specimens, once treated with formalin, are injected with a mixture made of gelatin containing a contrast product (barium) and then analyzed by microCT. The acquisition times that can exceed 24hours and metal sheets used for X-ray filtering vary according to the sample. The projection images are reconstructed to produce 2D sections. These are combined for the reconstruction of 3D models using a volume rendering software. Four examples will allow the imaging of microvascularization: the inferior alveolar nerve, the cerebral cortex and pia-mother, brain stem, central gray nuclei (ganglia at the base of the brain). Small capillaries are highlighted using high-end software for reconstruction. Conventional software or freeware cause a considerable loss of information on small vessels that are not visualized. The VGStudio max high-end software allows the production of videos that are particularly useful for 3D exploration and teaching (four videos are provided with this article).

Microcomputed tomography (microCT) and histology of the mandibular canal in human and laboratory animals.

The inferior alveolar nerve (IAN) is a sensitive branch of the trigeminal nerve. It has an intra-bone path in the mandible, inside the mandibular canal, where it is accompanied by lymph, venous and arterial vessels. We have studied the mandibular canal in human mandibles and in some laboratory animals (mice, rats, rabbits and cats). Microcomputed tomography evidenced that the walls of the canal are made with thin plates of trabecular bone with numerous fenestrations. This aspect is evidenced in dentate subjects and become more evident in edentulous subjects with atrophy of the alveolar bone. In rats and mice, the wall of the canal is also clearly composed of trabecular plates coming from the surrounding alveolar bone of the mandible. In the rabbit, similar findings are also observed but the trajectory of the canal is more difficult to identify. In the cat, the floor of the canal is composed of the cortical bone from the basilar cortex of the mandible and the roof has a trabecular nature. Vascular injections of gelatin-barium evidenced the arterial trajectories inside the bone in rats and humans. Undecalcified bone sections in human evidenced the histological aspect of the IAN and its connective sheets. Some nervous bundles can be observed outside the epineurium. Bone remodeling is observed on the wall of the mandibular canal. These descriptive findings have a clinical relevance in dental implantology or mandibular surgery.

Surgical anatomy for hemifacial spasm.

Classically in the cerebello-pontine angle the facial (CN VII) and vestibular-cochlear (CN VIII) nerves should run parallel with the anterior inferior cerebellar artery, whereas the lower nerves (CN IX-XI) continue with the posterior-inferior-cerebellar artery (PICA). In fact, this is not always true, particularly when dealing with hemispasm surgery where the relationships between CN VII, CN VIII and PICA are often different and closer. Knowledge of anatomical bases in surgical situation will help neurosurgeons to appreciate anatomical nuances, that are important to increase effectiveness and safety of hemifacial spasm surgery.

Multiple light scattering in metallic ejecta produced under intense shockwave compression.

A roughened metallic plate, subjected to intense shock wave compression, gives rise to an expanding ejecta particle cloud. Photonic Doppler velocimetry (PDV), a fiber-based heterodyne velocimeter, is often used to track ejecta velocities in dynamic compression experiments and on nanosecond time scales. Shortly after shock breakout at the metal-vacuum interface, a particular feature observed in many experiments in the velocity spectrograms is what appear to be slow-moving ejecta, below the free-surface velocity. Using Doppler Monte Carlo simulations incorporating the transport of polarization in the ejecta, we show that this feature is likely to be explained by the multiple scattering of light, rather than by possible collisions among particles, slowing down the ejecta. As the cloud expands in a vacuum, the contribution of multiple scattering decreases due to the limited field of view of the pigtailed collimator used to probe the ejecta, showing that the whole geometry of the system must be taken into account in the calculations to interpret and predict PDV measurements.

Introduction to primary hemifacial spasm: A neurosurgical disease.

Primary hemifacial spasm is a hyperactive cranial nerve syndrome. The cause is always a neurovascular compression, generally at the root exit zone from the brainstem. Its curative treatment is microvascular decompression, that may be performed as a first option, or secondarily when botulinum toxin injections fail.

Microvascular decompression for hemifacial spasm : Surgical techniques and intraoperative monitoring.

Primary hemifacial spasm with few exceptions is due to the vascular compression of the facial nerve that can be evidenced with high resolution MRI. Microvascular decompression is the only curative treatment for this pathology. According to literature review detailed in chapter "conflicting vessels", the compression is located at the facial Root Exit Zone (REZ) in 95% of the cases, and in 5% distally at the cisternal or the intrameatal portion of the root as the sole conflict or in addition to one at brainstem/REZ. Therefore, exploration has to be performed on the entire root, from the ponto-medullary fissure to the internal auditory meatus. Because microvascular decompression is functional surgery, the procedure should be as harmless as possible and with a high probability of permanent efficacy. Besides facial palsy, main complications are hearing loss, tinnitus and gait disturbances. Causes are cochlea/labyrinth ischemia due to manipulations of their nutrient arteries and/or stretching of the eight nerve complex. To minimize the latter, the approach should not be with lateral-to-medial retraction of the cerebellar hemisphere, but along an infra-floccular trajectory, from below. In fact, most of the neurovascular conflicts are situated ventro-caudally to facial REZ at the brainstem, particularly those from a megadolicho-vertebrobasilar artery and its posterior inferior-cerebellar branch. Also, care should be taken not to cause any injury of the manipulated vessels or stretching of their perforators to brainstem. Heating from bipolar coagulation must be avoided. The inserted material used to maintain the offending vessel(s) away must not be neo-compressive. Intraoperative neuromonitoring is considered to be useful for achieving safe surgery at least until the learning curve has reached an optimal level, particularly BrainstemAuditory Evoked Potentials recordings. Increase in latency and/or decrease in amplitude of wave V warn excessive stretching or damage to the cochlear nerve, and decrease in amplitude of wave I signals possible ischemia of the cochlea. Free-running EMG of the facial muscles may warn against excessive manipulation of the facial nerve. Recording of the lateral spread responses - which are a sign of hyperexcitabilty of the facial motor system - may provide information on completeness of the decompression.

Hemifacial spasm associated with other cranial nerve syndromes: Literature review.

Hyperactive dysfunction may affect all cranial nerves in the posterior fossa. According to literature review and personal experience, hemifacial spasm was found to be associated not only with the most frequent cranial nerve syndromes, namely: trigeminal neuralgia, vago-glossopharyngeal neuralgia or VIIIth nerve disturbances manifested by vertigo, tinnitus, hearing decrease, but also with rarer syndromes like geniculate neuralgia, masticatory spasm etc. Also, a number of publications have pointed out the relatively high incidence of the coexistence of hemifacial spasm and systemic blood hypertension; both can be cured by vascular decompression of the ventrolateral aspect of the medulla and IX-Xth route entry zone (REZ) together with the facial REZ. Even more complex clinical presentations have been encountered, corresponding to disturbances in several cranial nerve nuclei. Some could be attributed to neurovascular conflicts from elongated arteries invaginated into the brainstem, and cured by microvascular decompression surgery. When confronted with such complex, and therefore misleading, syndrome, it is advised to search for vascular conflicts at the brainstem using high-resolution MRI exploration.

The conflicting vessels in hemifacial spasm: Literature review and anatomical-surgical implications.

Since several decades, it has been established that so-called primary hemifacial spasm is linked to neuro-vascular conflicts in the facial nerve, especially its root exit zone (REZ). Based on our review of the detailed publications of literature (2489 patients), together with our own series (340 patients), the responsible vessels found at surgery were: the posterior inferior cerebellar artery in 47.2%, the anterior inferior cerebellar artery in 45.9%, the vertebro-basilar artery in 17.5%, another (smaller) artery in 11.7%. Participation of veins was very diversely estimated according to series: 4.9% on average. Multiple neuro-vascular conflicts in a same individual were frequently observed, in the order of 20 to 30% according to authors, 37% in our series. Also, abnormal conformation of the posterior fossa may play a role, such as flatness of the posterior fossa or exiguity of the cerebello-pontine angle cistern. Whatever, most neurovascular conflicts are located at brainstem and/or ventrocaudally to the facial REZ, in the order of 95% of the patients. The anatomical location and conformation of the compressive vessel(s) are crucial in determining the difficulties to identify the responsible conflict(s) and to perform effective and safe decompression. Main difficulties are encountered in cases with arteriosclerotic megadolicho-vertebrobasilar artery, at brainstem, especially when PICA and/or AICA come in association, or for neurovascular conflict(s) located at the cisternal or the intrameatal portions of the facial root. Later ones can be alone or in addition to NVC at brainstem/REZ.

PDV-based estimation of ejecta particles' mass-velocity function from shock-loaded tin experiment.

A metallic tin plate with a given surface finish of wavelength λ ≃ 60 µm and amplitude h ≃ 8 µm is explosively driven by an electro-detonator with a shock-induced breakout pressure PSB = 28 GPa (unsupported). The resulting dynamic fragmentation process, the so-called "micro-jetting," is the creation of high-speed jets of matter moving faster than the bulk metallic surface. Hydrodynamic instabilities result in the fragmentation of these jets into micron-sized metallic particles constituting a self-expanding cloud of droplets, whose areal mass, velocity, and particle size distributions are unknown. Lithium-niobate-piezoelectric sensor measured areal mass and Photonic Doppler Velocimetry (PDV) was used to get a time-velocity spectrogram of the cloud. In this article, we present both experimental mass and velocity results and we relate the integrated areal mass of the cloud to the PDV power spectral density with the assumption of a power law particle size distribution. Two models of PDV spectrograms are described. The first one accounts for the speckle statistics of the spectrum and the second one describes an average spectrum for which speckle fluctuations are removed. Finally, the second model is used for a maximum likelihood estimation of the cloud's parameters from PDV data. The estimated integrated areal mass from PDV data is found to agree well with piezoelectric results. We highlight the relevance of analyzing PDV data and correlating different diagnostics to retrieve the physical properties of ejecta particles.

Microvascular decompression for hemifacial spasm: Outcome on spasm and complications. A review.

Over the last decades microvascular decompression (MVD) has been established as the curative treatment of the primary Hemifacial Spasm (HFS), proven to be linked in almost all cases to a neurovascular compression of the facial nerve. Because the disease is not life-threatening and MVD not totally innocuous, efficacy and safety have to be weighted before decision taken of indicating surgery. The authors have been charged by the French Speaking Society of Neurosurgery to conduct a detailed evaluation of the probability of relief of the spasm that MVD is able to obtain, together with its potential complications. For the review, the authors have gone through the reports available from the Pubmed system. Eighty-two publications have been read and analysed, totalizing more than 10,000 operated cases. In most series, the percentage of patients with total relief ranged between 85% and 90%. Relief was obtained after a certain delay in as many as in 33%±8% of the patients in many series. For those, delay lasted around one year in 12% of them. When effect of MVD was considered achieved, relief remained permanent in all but 1%-2% of the long-term followed patients. As regards to complications, risk of permanent cranial nerve deficit was evaluated at 1%-2% for facial palsy, 2%-3% for non-functional hearing loss, 0.5%-1% for lower cranial nerve dysfunction. Risk of stroke was at 0.1% and mortality at 0.1%. CSF leakage and related complications could be reduced at less than 2% in most series provided careful closing techniques be applied. Complications were at a higher rate in repeated MVD. MVD is an effective curative method for almost all the patients affected with primary HFS. Because MVD for HFS is functional surgery, scrupulous consideration of its potential risks, together with the ways to avoid complications are of paramount importance. When MVD is estimated to have failed, it is wise to wait one year before considering to repeat surgery, as number of patients may benefit from delayed effect. This is the more so as important as repeated surgery entails a higher rate of complications.

Characterization of Staphylococcus caprae Clinical Isolates Involved in Human Bone and Joint Infections, Compared with Goat Mastitis Isolates.

Staphylococcus caprae is an emerging microorganism in human bone and joint infections (BJI). The aim of this study is to describe the features of S. caprae isolates involved in BJI (H for human) compared with those of isolates recovered in goat mastitis (A for animal). Fourteen isolates of each origin were included. Identifications were performed using a Vitek 2 GP ID card, tuf gene sequencing, and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) Vitek MS. Molecular typing was carried out using pulsed-field gel electrophoresis (PFGE) and DiversiLab technology. The crystal violet method was used to determine biofilm-forming ability. Virulence factors were searched by PCR. Vitek MS technology provides an accurate identification for the two types of isolates compared to that of gold-standard sequencing (sensitivity, 96.4%), whereas the Vitek 2 GP ID card was more effective for H isolates. Molecular typing methods revealed two distinct lineages corresponding to the origin despite few overlaps: H and A. In our experimental conditions, no significant difference was observed in biofilm production ability between H and A isolates. Nine isolates (5 H isolates and 4 A isolates) behaved as weak producers while one A isolate was a strong producer. Concerning virulence factors, the autolysin atlC and the serine aspartate adhesin (sdrZ) genes were detected in 24 isolates (86%), whereas the lipase gene was always detected, except in one H isolate (96%). The ica operon was present in 23 isolates (82%). Fibrinogen-binding (fbe) or collagen-binding (cna) genes were not detected by using primers designed for Staphylococcus aureus or Staphylococcus epidermidis, even in low stringency conditions. Although S. caprae probably remains underestimated in human infections, further studies are needed to better understand the evolution and the adaptation of this species to its host.

Representing virus-host interactions and other multi-organism processes in the Gene Ontology.

BACKGROUND: The Gene Ontology project is a collaborative effort to provide descriptions of gene products in a consistent and computable language, and in a species-independent manner. The Gene Ontology is designed to be applicable to all organisms but up to now has been largely under-utilized for prokaryotes and viruses, in part because of a lack of appropriate ontology terms. METHODS: To address this issue, we have developed a set of Gene Ontology classes that are applicable to microbes and their hosts, improving both coverage and quality in this area of the Gene Ontology. Describing microbial and viral gene products brings with it the additional challenge of capturing both the host and the microbe. Recognising this, we have worked closely with annotation groups to test and optimize the GO classes, and we describe here a set of annotation guidelines that allow the controlled description of two interacting organisms. CONCLUSIONS: Building on the microbial resources already in existence such as ViralZone, UniProtKB keywords and MeGO, this project provides an integrated ontology to describe interactions between microbial species and their hosts, with mappings to the external resources above. Housing this information within the freely-accessible Gene Ontology project allows the classes and annotation structure to be utilized by a large community of biologists and users.

Post-surgical vestibular schwannoma remnant tumors: What to do?

BACKGROUND: Vestibular schwannomas (VS) are benign tumors of the vestibular nerve's myelin sheath. The current trend in VS surgery is to preserve at the facial function, even if it means leaving a small vestibular schwannoma tumor remnant (VSTR) after the surgery. There is no defined therapeutic management VSTR. The aim of this study was to assess the evolution of the VSTR to define the best therapeutic management and identify predictive factors of VSTR progression. METHODS: Among the 256 patients treated surgically for VS in the Department of Neurosurgery at Angers University Hospital, 33 patients with a post-surgical VSTR were included in this retrospective study. For all surgical patients, the data collected were age at diagnosis, the Koos classification, the surgical access, the existence of a type 2 neurofibromatosis (NF2), the TR location and size on control MRI-scans. Patients had a bi-annual follow-up with clinical status and VSTR size assessment with MRI-scan. Survival analyzes were performed to determine the time and rate of VSTR progression, and identify factors of progression. RESULTS: The mean follow-up of the population was 51 months. All VS remnant progression occurred between 38 and 58 months after surgery. In non-NF2 patients with first follow-up MRI-scan three months after surgery, 43% presented a spontaneous regression, 50% a stability and 7% a progression of the VSTR. In the same population with the 1-year MR-scan after surgery as baseline, 25% presented a spontaneous regression, 62.5% a stability and 12.5% a VSTR progression. These data are consistent with the data reported in the literature. The post-operative facial function impairment and an initial remnant ≥ 1.5cm(3) were found to be significant risk factors of VS remnant progression in non-NF2 population in univariate analysis (P=0.048 and 0.031) but not in multivariate analysis. CONCLUSION: In our experience, the best therapeutic management of the post-surgical VSTP in non-NF2 patients with no risk factor of progression is a simple clinical radiological follow-up otherwise complementary radiosurgery should be considered.

Trabecular microarchitecture in established osteoporosis: relationship between vertebrae, distal radius and calcaneus by X-ray imaging texture analysis.

INTRODUCTION: Osteoporosis is an alteration of bone mass and microarchitecture leading to an increased risk of fractures. A radiograph is a 2D projection of the 3D bone network exposing a texture, that can be assessed by texture analysis. We compared the trabecular microarchitecture of the spine, radius and calcaneus in a series of osteoporotic cadavers. MATERIALS AND METHODS: Thirty-four cadavers (11 men, 23 women), mean age 85.2±2.1years, were radiographed from T4 to L5 to identify those with vertebral fractures (FV). Non-fractured vertebrae (NFV), radius and calcaneus were taken and analyzed by densitometry, radiography and texture analysis under run-length, skeletonization of the trabeculae, and fractal geometry. RESULTS: Six subjects (five women, one man) were selected, mean age 82.5±5.5years. Twelve calcanei and 10 radii were taken. Two radii were excluded. The texture of NFV was significantly correlated (P<0.01) with that of the radius for horizontal run-lengths. No relationship between the texture of NFV and calcaneus was found. DISCUSSION: In the horizontal direction (perpendicular to the stress lines), the microarchitecture of NFV and radius showed a disappearance of the transverse rods anchoring the plates. Due to its particular microarchitecture, the calcaneus is not representative of the vertebral status. CONCLUSION: Bone densitometry provides no information about microarchitecture. Texture analysis of X-ray images of the radius would be a minimally invasive tool, providing an early detection of microarchitectural alterations. LEVEL OF EVIDENCE: IV retrospective study.

[Anatomical study of the superficial cervical plexus: application to the prevention of the postoperative sensitive facial deficits]. / Étude anatomique du plexus cervical superficiel: application à la prévention des déficits sensitifs faciaux postopératoires.

INTRODUCTION: The cervical surgery can be complicated of postoperative facial sensory deficits, in particular in using the anterior presternocleidomastoid approach. The purpose of this study was to specify the routes and the links of nerves involved in these sensory deficits (great auricular nerve and transverse cervical nerve with the goal, to deducing, if possible, some modifications of the surgical practices to prevent the deficits. PATIENTS: Ten dissections of the superficial cervical plexus, on preserved anatomical subjects, were made from February till May 2009. Nerves and whole superficial venous network were dissected on all along their route to be able to make several measures of distances and angles. All the data were computerized treated by spreadsheet. RESULTS: The transverse cervical nerve appeared from the posterior edge of the sternocleidomasoid (SCM) muscle in 7.46 ± 1.81 cm s (5,1-10,0) of the clavicle, with an angle of 108.3 ± 8.15° (93-120). Its halving terminal branches was made in 2.92 ± 1.76 cm s (0,4-5,2) of the posterior edge of the SCM muscle, with an angle between these two branches of 74.0 ± 36.8° (40-120). The great auricular nerve appeared from the posterior edge of the muscle SCM in 8.96 ± 1.85 cm (6.4-12.0) of the clavicle, with an angle of 64.5 ± 23.39° (35-110), which modified secondarily to measure 39.5 ± 6.15° (27-45) in the middle of the SCM muscle. At this level, the great auricular nerve and the external jugular vein were almost parallel (1.3° of average difference) and the distance that separated them was 2.24 ± 0.79 cm (0.8-3.5). CONCLUSION: Our study gave us a precise description of the superficial cervical plexus. All the measures allowed the establishment of the routes and the links of these structures to propose peroperating actions to prevent these facial sensory deficits.

[Livedoid erythema of the lower back revealing thrombosed abdominal aortic aneurysm]. / Érythème lombaire livédoïde révélateur d'un anévrisme thrombosé de l'aorte abdominale.

BACKGROUND: We report the case of a patient presenting a very painful livedo of the lower back as well as paraparesis revealing a complicated abdominal aortic aneurysm. PATIENTS AND METHODS: A 61-year-old man was referred to our emergency unit for sudden lower back pain and weakness of the lower limbs. He had a large and very painful livedo racemosa on the lower back as well as partial neurological deficit of the lower limbs. Abdominal CAT revealed a bulky thrombosed infrarenal aortic aneurysm. Despite surgery, ischaemia worsened, leading to cutaneous then muscular and visceral necrosis, followed by death. DISCUSSION: Livedo racemosa of the lower limbs may be the consequence of thrombosis or embolism resulting from an abdominal aortic aneurysm. Livedo racemosa on other skin areas is uncommon but may be due to the same physiopathology. Neurological deficit is occasionally associated with a complicated abdominal aortic aneurysm or with surgical treatment thereof. However, to our knowledge, livedo on the back associated with neurological deficit has not yet been reported. Such an association should prompt practitioners to screen for a thrombosed aortic aneurysm. Furthermore, this condition is also likely to carry a poor prognosis because of the proximal secondary location of the thrombotic phenomenon, involving the lumbar arteries, which supply the medullar, cutaneous and muscular arteries.

Estimated prevalence of Mycobacterium avium subspecies paratuberculosis infection in herds of dairy goats in France.

A study of the prevalence of Mycobacterium avium subspecies paratuberculosis (MAP) infection in dairy goats was carried out in France, using a serological ELISA. One hundred and five herds were randomly selected in different regions, and all the goats aged six months or older (11,847 goats) were sampled. An estimation had previously been made of the accuracy of the ELISA, and the Rogan-Gladen estimator was used to convert apparent prevalence values into estimates of true prevalence values. Given that sensitivity and specificity at herd level are functions of sample size, and because the sizes of the herds varied considerably, the true prevalence of infection at herd level was estimated using a weighted average depending on the herd size stratum. At the level of the individual animal, the total true prevalence was estimated by applying a weighted average in accordance with the regional distribution of the animals in the target population. At herd level, apparent prevalence and estimated true prevalence were 55.2 and 62.9 per cent, respectively; at individual animal level they were 2.9 and 6.6 per cent, respectively. In herds that were seropositive for MAP, the average within-herd apparent prevalence was 5.9 per cent and the estimated average within-herd true prevalence was 11.1 per cent.

[Orbital tumors. Neurosurgical activity]. / Tumeurs orbitaires. Activité neurochirurgicale.

In this chapter, we report the results of orbital tumor management in a few neurosurgical departments and compare it to a Paris neurosurgical department that has developed a close relation with an ophthalmological department. These departments' activity is quite low, treating mainly sphenoorbital meningiomas. Other tumor groups are unequally and sporadically managed.