Observation of quantum topological Hall effect in the Weyl semimetal candidate HgSe.

The magnetoresistance (MR) and Hall effect of a single HgSe crystal with an extremely low electron concentration of 8.8 × 1015 cm-3 were studied in a quantising magnetic field applied both along and across the direction of the electric current. As the result, a broad plateau was discovered in the ordinary (transverse) Hall resistance in the quantum limit. Within a framework of quantum spin Hall effect for an inversion breaking Weyl semimetal, we associate this plateau with a contribution to Hall conductivity from Chern insulator edge states when only a zero Landau level is occupied. In addition to the plateau in the quantum limit, we also detected a well-developed plateau-like behaviour in a phenomenologically-introduced 'longitudinal' Hall resistivity. In the 'longitudinal' Hall conductivity, a step-like behaviour was revealed, which we identify with the discovery of half-integer quantum spin Hall effect in HgSe. This effect, being purely topological in origin, supplements the non-trivial Weyl semimetal physics and may serve as a promising magnetotransport method for the detection of Weyl nodes in a studied material.

Nontrivial topology of bulk HgSe from the study of cyclotron effective mass, electron mobility and phase shift of Shubnikov-de Haas oscillations.

In this paper, the authors report the results of an experimental study of effective mass, electron mobility and phase shift of Shubnikov-de Haas oscillations of transverse magnetoresistance in an extended electron concentration region from 8.8 × 1015 cm-3 to 4.3 × 1018 cm-3 in single crystals of mercury selenide. The revealed features indicate that Weyl semimetal phase may exist in HgSe at low electron density. The most significant result is the discovery of an abrupt change of Berry phase [Formula: see text] at electron concentration [Formula: see text] 2 × 1018 cm-3, which we explain in terms of a manifestation of topological Lifshitz transition in HgSe that occurs by tuning Fermi energy via doping.

Imaging of non-operated cholesteatoma: clinical practice guidelines.

Middle ear cholesteatoma is an aggressive form of chronic otitis media requiring surgical therapy. The surgical strategy depends on the location of the lesion, its extensions to the middle ear and mastoid, the anatomical conformation of the tympanomastoid cavities and the health status of the patient (as well as his or her interest in aquatic leisure activities). For several years, imaging of the ear has been a routine test in the preoperative work-up of the disease. National guidelines for the topic "Imaging of non-operated middle ear cholesteatoma" were prepared in October 2010, for the annual congress of the French Society of Otolaryngology Head and Neck Surgery (SFORL), by a panel of experts from the SFORL, represented by the French Association of Otology and Neuro-otology (AFON), and the French Radiological Society (SFR), represented by the French Society of Head and Neck Imaging (CIREOL). These guidelines are presented in the present article.

Outpatient tonsillectomy in children: a 7-year experience.

OBJECTIVES: To report our centre's experience of outpatient tonsillectomy in children over a 7-year period and to evaluate the postoperative complication rate in this type of procedure compared to tonsillectomy performed in the context of conventional hospitalisation. MATERIAL AND METHODS: Retrospective review of medical charts. RESULTS: From May 2002 to April 2009, 276 tonsillectomies were performed on an outpatient basis, i.e. 55.4% of all paediatric tonsillectomies, in children with a mean age of 5.28 years. Ninety-six children (34.8%) presented clinical OSAS. Development of an early postoperative complication (before H8) required conventional hospitalisation on D0 in six (2.1%) of these 276 children operated on an outpatient basis: early postoperative bleeding in four cases (1.4%), which required reoperation to control bleeding in three cases, refusal to feed in one case (0.3%), and a parental problem in one case (0.3%). Postoperative complications occurring after H8 required readmission in six cases (2.1%): pain and feeding difficulties in two cases (0.7%) on D1 and D5, respectively, bleeding in four cases (1.4%) with reoperation before H24 for one patient, D5 for two patients and D7 for one patient. Only one case of bleeding occurred between H8 and H24. No perioperative respiratory complications were observed in children with clinical OSAS. CONCLUSION: The results of this study show that, in line with international publications and meta-analyses, post-tonsillectomy complications between H8 and H24 postoperatively, mainly bleeding, are exceptional. Respiratory complications usually occur in high-risk clinical settings that are not eligible for outpatient surgery. Outpatient tonsillectomy is therefore a safe procedure in children presenting all of the required medical, social and organizational conditions.

Growth hormone excess and sternohyoid muscle mechanics in rats.

In vitro isotonic and isometric mechanical properties of the sternohyoid (SH) muscle, an upper airway dilator muscle, were studied in rats with a growth hormone (GH)-secreting tumour (GH tumour group; n = 10). The effects of muscle fatigue were also studied. Stress and shortening were measured in muscles contracting from zero load up to isometric load under tetanic conditions. Isometric stress and maximum unloaded shortening velocity were determined and compared with values obtained from control rats (n = 10). Crossbridge kinetics and energetics and mechanical efficiency were calculated from Huxley's equations. Compared with controls, isometric stress, mechanical efficiency, crossbridge number and crossbridge single force were lower in the GH tumour group. The probability of crossbridge being in the power stroke configuration was lower in the GH tumour group than in controls. Muscle fatigue significantly impaired maximal muscle efficiency and crossbridge single force in the GH tumour group but not in controls. In conclusion, mechanical and energetic properties of the SH muscle and crossbridge properties were worse in the GH tumour group than in controls. This may partly account for impairment of the upper airway dilator muscle function and the increased occurrence of obstructive sleep apnoea in acromegaly.

Relevance of Choukroun's Platelet-Rich Fibrin (PRF) and SMAS flap in primary reconstruction after superficial or subtotal parotidectomy in patients with focal pleiomorphic adenoma: a new technique.

AIM OF THE STUDY: Parotidectomy leaves a retromandibular hollow area in proportion with the amount of gland resected. Many surgeons perform primary reconstruction after superficial or subtotal parotidectomy in patients with exo-facial pleiomorphic focal adenoma. Many techniques have been proposed. We present a new technique of filling of the parotidectomy chamber by a second generation leucocyte and platelet concentrate, Platelet-Rich Fibrin (PRF, Choukroun's method). PATIENTS AND METHODS: 10 patients were included in this preliminary study. Subtotal parotidectomy was performed through classic procedure or lifting procedure. The macroscopic security margin of resection usually allowed performance of a SMAS flap. PRF was prepared following the original Choukroun's method. RESULTS AND DISCUSSION: PRF slow resorption after filling of the exeresis cavity, offers a key aesthetic interest. The fibrin matrix of this biomaterial has many angiogenic and healing properties. Synergetic action of the fibrin and the platelets cytokines within PRF may improve revascularization and postoperative resumption of facial nerve function. The membrane formed by the fibrin dense fibrillary network, as well as the SMAS flap, may help to prevent the Frey's syndrome. CONCLUSION: We propose the use of PRF as a filling, healing and interposition material after parotidectomy for benign parotid tumors. Preliminary results are very encouraging. Longer prospective evaluation of this technique is necessary.

Chiari malformation and sleep related breathing disorders.

OBJECTIVE: To estimate the frequency, mechanisms and predictive factors of sleep apnoea syndrome (SAS) in a large group of children and adults with type I (CMI) and II (CMII) Chiari malformation (CM). BACKGROUND: The anatomical and functional integrity of both respiratory circuits and lower cranial nerves controlling the upper airway is necessary for breathing control during sleep. These latter structures may be altered in CM, and a few investigations have reported CM related sleep disordered breathing. METHODS: Forty-six consecutive unrelated patients with CM (40 CMI, six CMII), of which 20 were children (eight males) and 26 were adults (12 males), underwent physical, neurological and oto-rhino-laryngoscopic examination, MRI and polysomnography. RESULTS: SAS was present in 31 (67.4%) of the patients with CM (70% of CMI, 50% of CMII, including mainly children). Sixty per cent of children with CM exhibited SAS, including 35% with obstructive (OSAS) and 25% with central (CSAS) sleep apnoea syndrome. SAS was observed in 73% of CM adults (57.7% OSAS, 15.4% CSAS). Severe SAS was found in 23% of CM adults. Multiple regression analysis revealed that age, type II Chiari and vocal cord paralysis predicted the central apnoea index. CONCLUSION: SAS is highly prevalent in all age groups of patients suffering from CM. CSAS, a rare condition in the general population, was common among the patients with CM in our study. Sleep disordered breathing associated with CM may explain the high frequency of respiratory failures observed during curative surgery of CM. Our results suggest that SAS should be systematically screened for in patients with CM, especially before surgery.

Lower respiratory tract foreign bodies: a retrospective review of morbidity, mortality and first aid management.

OBJECTIVES: The authors describe 28 pediatric cases of foreign body inhalation requiring treatment in intensive care units between 1987 and 1999. The purpose of this study was: (1) to analyze the circumstances, diagnostic difficulties and initial treatment of serious foreign bodies and (2) to compare our series with other literature descriptions and define principles for optimal prevention and initial treatment. METHODS: Twenty-one children presented a penetration syndrome, which was responsible in 13 cases for asphyxia with cardiorespiratory arrest. All these children died, regardless of the initial treatment. Seven children were hospitalized for apparent asthmatic symptoms that did not respond to traditional treatment. RESULTS: The inefficiency of external extraction methods like the Heimlich maneuver and the mean delay between clinical signs and initial treatment lead us to propose a new strategy for the emergency treatment of foreign bodies with asphyxia. CONCLUSIONS: We recommend that emergency teams promote the use of a laryngoscope and Magill forceps. Flexible endoscopy is still recommended as the appropriate diagnostic tool to eliminate doubt in the case of a first severe asthma attack.

[Locoregional recurrences of HNSCC: place of re-irradiations]. / Récidives locorégionales des carcinomes des voies aérodigestives supérieures: place des ré-irradiations.

Unresectable forms of HNSCC relapses occurring in a previously irradiated area are relatively common and may be difficult to manage from a therapeutic point of view. Full dose re-irradiation with concomitant chemotherapy constitutes an alternative to palliative chemotherapy. Indeed, the feasibility of this approach has been shown, and may be associated with a curative potential in a relatively low proportion of these relapses.

[Squamous cell carcinoma in a thyroglossal duct cyst]. / Carcinome épidermoïde sur kyste du tractus thyréogosse.

OBJECTIVE: To present a case of squamous cell carcinoma developed on a thyroglossal duct cyst in an adult patient. Modalities of treatment and prevention are discussed. PATIENT AND METHODS: A 55-year-old woman had a thyroglossal duct cyst since childhood. Surgical resection had not been performed because of parental refusal. RESULTS: Diagnosis of malignant degeneration was suggested by an increase in volume associated with cervical pain. Surgery was incomplete because of carotid artery and laryngeal involvement. Postoperative radiotherapy was given. At two years follow-up, local progression was controlled by palliative chemotherapy. DISCUSSION: For most authors, the risk of recurrent infections is the main reason for surgical resection of a thyroglossal duct cyst during childhood. The risk of malignant degeneration is generally not put forward. It is rather uncommon for carcinoma to develop on a thyroglossal duct cyst. The risk is probably underestimated because surgery is generally performed early in childhood. CONCLUSION: This observation of malignant degeneration emphasizes the importance of surgical resection of thyroglossal duct cysts during childhood. We discuss treatment in the event of malignant degeneration.

[Nasal obstruction and compliance to nasal positive airway pressure]. / Obstruction nasale et compliance à la ventilation nasale à pression positive.

UNLABELLED: Obstructive sleep apnea syndrome is a very common disease. Nasal continuous positive airway pressure is a useful and efficient treatment but compliance depends on several factors including the degree of nasal obstruction. OBJECTIVES: The aim of this study was to evaluate the effects of surgical correction of nasal obstruction on compliance to nasal continuous positive airway pressure in obstructive sleep apnea syndrome. MATERIAL AND METHODS: This retrospective study (from March 1998 to March 2000) included ten patients suffering from a severe obstructive sleep apnea syndrome (apnea-hypopnea index greater than 30 per hour) treated by nasal continuous positive airway pressure for at least three months and presenting an anatomic nasal obstruction limiting the use of nasal continuous positive airway pressure. Surgical procedures included one septoplasty, two inferior turbinectomies and seven septoplasties with turbinectomies. RESULTS: The post-operative polysomnography showed that surgical correction of nasal obstruction had no effect on obstructive sleep apnea syndrome severity (no significative change of apnea hypopnea index after surgery) but allowed the use of lower nasal continuous positive airway pressure levels (7.1 mmHg after surgery versus 10 mmHg before) and improved compliance to treatment (six compliant patients after surgery versus no compliant patient before). These results were compared with those published in the literature. CONCLUSION: An examination of the nose has to be performed before initiating nasal continuous positive airway pressure. If nasal continuous positive airway pressure cannot be tolerated because of nasal obstruction, surgery is required to improve compliance and tolerance to treatment.

Sinonasal Wegener's granulomatosis: CT characteristics.

Wegener's granulomatosis (WG) is a severe and potentially lethal granulomatosis. Even though no specific radiological criteria exist, CT may suggest the correct diagnosis at an early stage. Recent improvement in the prognosis is related to earlier diagnosis, allowing the initiation of efficient and specific treatment before any severe complications occur. We reviewed a series of WG cases in order to establish the CT diagnostic criteria.

[Sinusal penetration of amoxicillin-clavulanic acid. Formulation 1 g./125 mg., twice daily versus formulation 500 mg./125 mg., three times daily]. / Pénétration sinusienne de l'amoxicilline-acide clavulanique. Formulation 1 g/125 mg, 2 fois/jour, versus formulation 500 mg/125 mg, 3 fois/jour.

INTRODUCTION: In order to meet the evolution of pneumococcus resistance to beta-lactam antibiotics, a new formulation of amoxicillin (AMX) and clavulanic acid (CA), with twice as much AMX (1 g/125 mg vs. 500 mg/125 mg) was developed for the treatment of acute pneumonia in patients at risk. This formulation can also be used in the treatment of acute maxillary sinusitis using a 1 g/125 mg regimen twice-daily. OBJECTIVES: Compare the sinusal penetration of AMX and CA (1 g/125 mg twice-daily vs. 500 mg/125 mg three times a day) when administered at both regimens to demonstrate equivalent pharmacokinetic and pharmacodynamic behaviour of the former when compared to the latter. METHODS: Concentrations of AMX and CA were measured in the anterior ethmoid, maxillary, posterior ethmoid sinus and in the middle nasa concha in 62 patients undergoing surgery for nasosinusal polyps. Patients randomised in two groups corresponding to 2 oral regimens, received either 1 g/125 mg twice a day or 500 mg/125 mg three times a day for 4 days. The last dose in both groups was administered 1 h 30, 3, 5 or 8 hrs prior to surgery. Serum samples were taken simultaneously to tissue samples. AMX and CA were measured by high performance liquid chromatography. Exogenous and above all endogenous blood contamination were taken into account with the hematocrit as well as blood and tissue haemoglobin concentrations. Comparisons of tissue concentrations were made for each sampling time, according to values obtained for a specific tissue with both doses on one hand, and on the other to values obtained with a specific dose in different tissues. The calculated pharmacodynamic parameters, which are considered to be predictive for bacteriological and clinical efficacy, result directly from tissue concentrations of AMX. tissue inhibitory quotients (IQtissue = Tissue concentration/MIC). time above MICs for serum and tissue concentrations (T > MIC). RESULTS: As regards AMX, whatever the dose, at 1 h 30 and at 3 hrs, tissue concentrations did not differ significantly whatever the tissue studied (from 1.1 to 2.5 micrograms/g). Conversely, at 5 and 8 hrs, they were greater than after the 1 g/125 mg regimen given twice-daily (0.06-0.7 vs. 0.7-1.8 micrograms/g). If we consider a given dose, the comparison between the various tissues showed identical concentrations in the four tissues studied at each sampling time, except in two cases with the dose of 500 mg/125 mg 3 times a day. T > MIC for serum and tissue showed higher values than those required for AMX/pneumococcus association (40-50%) with, nevertheless, greater tissue values for the 1 g/125 mg dose given twice-daily when MIC was of 1 microgram/ml (40-52% vs. 50-66%). The maximum tissue inhibitory quotients were also greater with the twice-daily 1 g/125 mg dose, when calculated with MIC 50 or 90 of S. Pneumoniae, H. influenzae, M. catarrhalis or S. pyogenes. As for CA, concentrations were equivalent for both doses at each sampling time and greater than those required in vitro during respectively 4 and 5 hours for beta-lactamases H. influenzae and M. catarrhalis. DISCUSSION-CONCLUSION: A least an equivalence between both dose regimens was observed, with occasionally a superiority of the twice-daily 1 g/125 mg dose, in terms of pharmacokinetics, tissue penetration and pharmacodynamics for both AMX and CA. This new regimen therefore appears more appropriate for the treatment of acute maxillary sinusitis in adults.

A prospective, multicentre study of moxifloxacin concentrations in the sinus mucosa tissue of patients undergoing elective surgery of the sinus.

A pharmacokinetic study was carried out to determine moxifloxacin concentrations in sinus tissue, after oral moxifloxacin 400 mg once daily for 5 days to patients with chronic sinusitis, undergoing elective sinus surgery. Patients were randomly allocated to one of seven treatment groups, in which tissues were sampled 2, 3, 4, 6, 12, 24 or 36 h post-dose. A control group with non-infected nasal polyps was also included. Forty-eight patients (13 female, 35 male, mean age 47.1 years) were allocated to one of each active treatment group (n = 42) or to the control group (n = 6). Tissue and plasma samples were taken simultaneously and stored frozen until assayed by HPLC. Thirty-nine patients were fully valid for pharmacokinetic analysis. The geometric mean moxifloxacin plasma concentration increased from 2.32 mg/L at 2 h to a maximum of 3.37 mg/L at 4 h post-dose, decreasing to 0.37 mg/L at 36 h post-dose. The moxifloxacin concentration in sinus mucosa was consistently greater than that in plasma being 4.56-5.73 mg/kg from 2 to 6 h and 2.81-1.25 mg/kg from 12 to 36 h post-dose. The elimination rates in plasma and sinus tissues were similar. The tissue/plasma ratio was c. 200% between 2 and 6 h, and up to 328.9% at 36 h. Results were similar whatever the site of tissue sampling (maxillary sinus, anterior ethmoid sinus or nasal polyps). Tissue levels exceeded the MIC(90) of all pathogens commonly causing acute sinusitis (e.g. 5-30 x MIC for Streptococcus pneumoniae: 0.25 mg/L). These results sup-port the use of moxifloxacin 400 mg once daily as a regimen for the treatment of sinus infections.

Full dose reirradiation combined with chemotherapy after salvage surgery in head and neck carcinoma.

BACKGROUND: The purpose of this study was to analyze the tolerance and efficacy of full dose reirradiation combined with chemotherapy in patients with head and neck carcinoma (HNC) with a high risk of recurrence after salvage surgery. METHODS: Between 1991 and 1996, 25 patients having a recurrence or a second primary tumor in a previously irradiated area (> 45 grays [Gy]) were entered in this prospective study. All of them received salvage surgery and had a positive surgical margin and/or lymph node involvement with capsular rupture (N+R+). Adjuvant radiochemotherapy was given, delivering 60 Gy per 30 fractions with concomitant hydroxyurea and 5-fluorouracil. The median total cumulative dose of the 2 irradiations was 118 Gy. The median follow-up after the second irradiation was 66 months. RESULTS: During the reirradiation course, Grade 3 and 4 mucositis were observed in 40% and 12%, respectively. Analysis of late effects (> 6 months after reirradiation) showed that 16% of the patients had osteoradionecrosis and 40% had Grade 2-3 cervical fibrosis (Radiation Therapy Oncology Group scoring system). The patterns of failure were as follows: local only (n = 9), lymph node only (n = 2), local and lymph node only (n = 1), and metastatic (n = 4). The 4-year survival rate after reirradiation was 43% (95% confidence interval, 25-62). CONCLUSIONS: Full dose reirradiation combined with chemotherapy after salvage surgery in high risk patients with HNC was feasible with an "acceptable" toxicity and led to a relatively good 5-year survival rate. These results prompted the authors to initiate a multicentric randomized trial that is ongoing (GETTEC-GORTEC 99-01) to evaluate the benefit of adjuvant radiochemotherapy in these types of patients.

Chondromyxoid fibroma of the nasal bone with extension into the frontal and ethmoidal sinuses: report of one case and a review of the literature.

Chondromyxoid fibroma is a rare benign tumor that usually occurs in the long bones. A 50-year-old patient presented with chondromyxoid fibroma of the nasal bone with extension into the frontal and ethmoidal sinuses. This is the fourth case reported to date in the literature. The clinical manifestations of the tumor were very limited, and the appearance at rhinoscopy was misleading. Radiologic imaging showed a soft tissue lesion invading the adjacent bony structures and the dura mater. Surgery was performed by a combined team of otorhinolaryngologists and neurosurgeons, and total excision of the tumor was achieved. The histologic diagnosis of this tumor is difficult because of its similarities to chondrosarcoma. [Editorial comment: The authors concisely review management of this rare tumor, emphasizing that complete surgical excision, rather than curettage, is required for long term control.]