An interdimensional correlation framework for real-time estimation of six degree of freedom target motion using a single x-ray imager during radiotherapy

Increasing evidence suggests that intrafraction tumour motion monitoring needs to include both 3D translations and 3D rotations. Presently, methods to estimate the rotation motion require the 3D translation of the target to be known first. However, ideally, translation and rotation should be estimated concurrently. We present the first method to directly estimate six-degree-of-freedom (6DoF) motion from the target's projection on a single rotating x-ray imager in real-time. This novel method is based on the linear correlations between the superior-inferior translations and the motion in the other five degrees-of-freedom. The accuracy of the method was evaluated in silico with 81 liver tumour motion traces from 19 patients with three implanted markers. The ground-truth motion was estimated using the current gold standard method where each marker's 3D position was first estimated using a Gaussian probability method, and the 6DoF motion was then estimated from the 3D positions using an iterative method. The 3D position of each marker was projected onto a gantry-mounted imager with an imaging rate of 11 Hz. After an initial 110° gantry rotation (200 images), a correlation model between the superior-inferior translations and the five other DoFs was built using a least square method. The correlation model was then updated after each subsequent frame to estimate 6DoF motion in real-time. The proposed algorithm had an accuracy (±precision) of  -0.03  ±  0.32 mm, -0.01  ±  0.13 mm and 0.03  ±  0.52 mm for translations in the left-right (LR), superior-inferior (SI) and anterior-posterior (AP) directions respectively; and, 0.07  ±  1.18°, 0.07  ±  1.00° and 0.06  ±  1.32° for rotations around the LR, SI and AP axes respectively on the dataset. The first method to directly estimate real-time 6DoF target motion from segmented marker positions on a 2D imager was devised. The algorithm was evaluated using 81 motion traces from 19 liver patients and was found to have sub-mm and sub-degree accuracy.

Chronic nasal dysfunction

Chronic nasal dysfunction is a clinical concept in the diagnostic and therapeutic management of sinonasal diseases, based on the evo-devo theory of formation of the nose according to which the nose is not a single organ but rather an association of three organs: olfactory nose, respiratory nose and paranasal sinuses. In chronic nasal dysfunction theory, etiological diagnosis takes account of the possible pathophysiological independence of nasal symptoms, in accordance with the different origins and physiology of the three organs constituting the nose. The diagnostic approach of the chronic nasal dysfunction concept breaks down the pathology so as to propose treatment(s) adapted to the diseased organ(s) and to the capacity for physiological resolution of dysfunction induced in one organ by pathology in a neighboring nasal organ. The ethmoid is not a sinus according to evo-devo, and therefore functional endoscopic endonasal surgery (FEES) cannot be restricted to functional endoscopic sinus surgery (FESS). Evo-devo theory and the chronic nasal dysfunction concept offer an alternative to the concept of chronic rhinosinusitis with or without polyps for the management of sinonasal diseases.

Endoscopic surgery of the olfactory cleft

The olfactory cleft is the specific site of development of many tumours (respiratory epithelial adenomatoid hamartoma, intestinal-type adenocarcinoma, neuroblastoma, inverted papilloma, glomangiopericytoma, etc.) and is also the site of CSF rhinorrhoea via the cribriform plate (cribri-rhinorrhoea). Olfactory cleft surgery must therefore be considered to be a specific type of surgery, complementary to ethmoidal labyrinth surgery and anterior skull base surgery. Olfactory cleft tumours can be resected according to five different surgical procedures: olfactory cleft mucosal resection, partial resection of the olfactory cleft, total resection of the olfactory cleft, unilateral endoscopic anterior skull base resection, and bilateral endoscopic anterior skull base resection. The diagnosis and closure of cribri-rhinorrhoea (i.e. documented CSF rhinorrhoea, demonstrated to arise from the cribriform plate during endoscopic examination of the olfactory cleft under general anaesthesia in a patient with no localizing signs on imaging) completes this range of treatment options.

Sinonasal symptom-related sleep disorders before and after surgery for nasal polyposis

BACKGROUND

Patients with nasal polyposis (NP) complain of several sinonasal symptoms that impact their sleep and quality of life. However, data on sleep disorders related to NP symptoms, before and after surgery, is poor. The aim of the present study was to analyze sleep complaints related to each NP symptom, before and after surgery, using the Dynachron questionnaire.

METHODOLOGY

63 patients operated for NP were included in this prospective study. They filled the DyNaChron questionnaire one day before surgery (V0), 6 weeks (V1) and 7 months (V2) after surgery. The self-ratings (0-10 point visual analog scale) of nasal obstruction, anterior rhinorrhea, postnasal discharge, cough and 5 items related to sleep disturbances, due to each symptom of chronic nasal dysfunction, were extracted from the questionnaire and analyzed.

RESULTS

There was significant improvement of symptoms and symptom-related sleep disturbance scores at V1 and V2 compared to baseline scores. Before surgery, moderate/severe sleep disorders that patients attributed to nasal obstruction (the patient thinks it is due to nasal obstruction rather than a clinical test to show nasal obstruction) or anterior rhinorrhea were reported in two thirds of patients, postnasal discharge in one half, and chronic cough in one third. After surgery, less than 10% of patients reported moderate/severe sleep disorders at V1. There was a mild increase of patients who rated moderate/severe sleep disorders at V2 in comparison to V1. The correlation between scores of nasal obstruction and its impacts on sleep quality was weak before surgery and strong afterwards.

CONCLUSION

Nasalization improved sleep quality significantly at 6 weeks and at 7 months after surgery. However, there was a mild increase of complaints related to postnasal discharge and cough at 7 months after surgery.

Comparison of Kaposi Sarcoma Risk in Human Immunodeficiency Virus-Positive Adults Across 5 Continents: A Multiregional Multicohort Study

BACKGROUND

We compared Kaposi sarcoma (KS) risk in adults who started antiretroviral therapy (ART) across the Asia-Pacific, South Africa, Europe, Latin, and North America.

METHODS

We included cohort data of human immunodeficiency virus (HIV)-positive adults who started ART after 1995 within the framework of 2 large collaborations of observational HIV cohorts. We present incidence rates and adjusted hazard ratios (aHRs).

RESULTS

We included 208140 patients from 57 countries. Over a period of 1066572 person-years, 2046 KS cases were diagnosed. KS incidence rates per 100000 person-years were 52 in the Asia-Pacific and ranged between 180 and 280 in the other regions. KS risk was 5 times higher in South African women (aHR, 4.56; 95% confidence intervals [CI], 2.73-7.62) than in their European counterparts, and 2 times higher in South African men (2.21; 1.34-3.63). In Europe, Latin, and North America KS risk was 6 times higher in men who have sex with men (aHR, 5.95; 95% CI, 5.09-6.96) than in women. Comparing patients with current CD4 cell counts ≥700 cells/µL with those whose counts were <50 cells/µL, the KS risk was halved in South Africa (aHR, 0.53; 95% CI, .17-1.63) but reduced by ≥95% in other regions.

CONCLUSIONS

Despite important ART-related declines in KS incidence, men and women in South Africa and men who have sex with men remain at increased KS risk, likely due to high human herpesvirus 8 coinfection rates. Early ART initiation and maintenance of high CD4 cell counts are essential to further reducing KS incidence worldwide, but additional measures might be needed, especially in Southern Africa.

Optomechanical properties of GaAs/AlAs micropillar resonators operating in the 18 GHz range

Recent experiments demonstrated that GaAs/AlAs based micropillar cavities are promising systems for quantum optomechanics, allowing the simultaneous three-dimensional confinement of near-infrared photons and acoustic phonons in the 18-100 GHz range. Here, we investigate through numerical simulations the optomechanical properties of this new platform. We evidence how the Poisson's ratio and semiconductor/vacuum boundary conditions lead to very distinct features in the mechanical and optical three-dimensional confinement. We find a strong dependence of the mechanical quality factor and strain distribution on the micropillar radius, in great contrast to what is predicted and observed in the optical domain. The derived optomechanical coupling constants g₀ reach ultra-large values in the 10⁶ rad/s range.

Effects of stretching on the frictional stress of rubber

In this paper, we report on new experimental results on the effects of in-plane surface stretching on the friction of poly(dimethylsiloxane) (PDMS) rubber with smooth rigid probes. Friction-induced displacement fields are measured at the surface of the PDMS substrate under steady-state sliding. Then, the corresponding contact pressure and frictional stress distributions are determined from an inversion procedure. Using this approach, we show that the local frictional stress τ is proportional to the local stretch ratio λ at the rubber surface. Additional data using a triangular flat punch indicate that τ(λ) relationship is independent on the contact geometry. From friction experiments using pre-stretched PDMS substrate, it is also found that the stretch-dependence of the frictional stress is isotropic, i.e. it does not depend on the angle between stretching and sliding directions. Potential physical explanations for this phenomenon are provided within the framework of Schallamach's friction model. Although the present experiments are dealing with smooth contact interfaces, the reported τ(λ) dependence is also relevant to the friction of statistically rough contact interfaces, while not accounted for in related contact mechanics models.

Non-enhanced CT Maximum Intensity Projections for the Detection of Large Vessel Occlusions

BACKGROUND

Identification of large vessel occlusions (LVO) is important with recent guidelines supporting endovascular therapy in selected acute ischemic stroke patients. Many stroke centers perform CT angiography (CTA) in patients with suspected LVO, however this requires additional time and contrast administration. Non-enhanced CT maximum intensity projection (NECT-MIPs) may offer a rapid alternative to CTA.

METHODS

We retrospectively reviewed acute stroke patients with LVO in the UCSD Stroke Registry, presenting between 6/2014-7/2016. NECT-MIPs were evaluated for presence of LVO. Gold standard comparison was to CTA. Results were stratified by level of training (Faculty, Fellow and Acute Care Practitioners [ACPs]). Inter-rater agreement was assessed using Fleiss' Kappa Coefficient.

RESULTS

We reviewed 24 patients using NECT-MIPs for the detection of LVO. Faculty had a sensitivity and specificity of 95% & 92% for ICA/M1, 42% & 100% for M2, and 67% & 96% for basilar occlusions. Fellows and ACPs had a sensitivity and specificity of 61% & 94% for ICA/M1, 19% & 83% for M2, and 75% & 95% for basilar occlusions. Inter-rater agreement among Faculty readers was k=0.75 for ICA/M1, k=0.79 for M2 and k=0.14 for basilar occlusions. Among Fellows and ACPs, k=0.57 for ICA/M1, k=0.40 for M2, and k=0.27 for basilar occlusions.

CONCLUSIONS

NECT-MIPs have high sensitivity and specificity for the detection of LVO when compared to CTA. Inter-rater agreement is fair and higher amongst more experienced reviewers. These results suggest that NECT-MIPs may be helpful to streamline the identification of LVO and reduce door to needle and door to intervention times.

"Watchful observation" follow-up scheme after endoscopic CO2 laser treatment for small glottic carcinomas: A retrospective study of 93 cases

OBJECTIVES

Evaluate the clinical outcome of patients treated with CO₂ laser surgery for early-stage glottic carcinomas followed up with 3-month laryngoscopy regardless of tumor grade and margins.

DESIGN

Case series.

SETTING

Retrospective review of the clinical records of patients treated at the ENT department of a tertiary university hospital.

PARTICIPANTS AND METHOD

Clinical records from patients with early-stage glottic carcinomas (Tis/T2) treated with curative intent by CO₂ laser surgery in a ten-year period were evaluated. Regardless of tumor margin status, patients underwent fiber endoscopy 6 weeks after surgery and a systematic second look by direct laryngoscopy under general anesthesia at 3 months.

MAIN OUTCOME MEASURES

Local control, laryngeal preservation rate.

RESULTS

Ninety-three patients were included. Disease control was obtained in 90/93 cases. Laryngeal preservation rate was 96.8%. Twenty patients had a local residual disease or recurrence after the first laser surgery, but 17 were salvaged (85%). Local residual disease and recurrence were more frequent in patients with advanced disease (T1b/T2), invasion of anterior commissure and "non-safe" margins.

CONCLUSION

The proposed follow-up scheme might be a valuable option, but with caution for positive or unevaluable margins as the latter is an independent risk factor for local recurrence. An early laser excision procedure (eg, within the first two months after surgery) or an alternative strategy may be discussed in this situation. "Watchful observation" should be reserved for compliant patients only so that the risk of missing potential recurrences is minimised.

Awareness of obstructive sleep apnea-hypopnea syndrome among the general population of the Lorraine Region of France

OBJECTIVE

Obstructive sleep apnea-hypopnea syndrome (OSAHS) seems to be underdiagnosed. The aim of this study was to assess awareness of OSAHS among the general population of the Lorraine Region of France.

METHODS

A descriptive epidemiological study was carried out from July to November 2015 in the Lorraine Region, using an anonymous questionnaire that assessed knowledge of OSAHS-related symptoms and complications. The survey was also circulated on the Internet via social media. Exclusion criteria comprised age under 18 years, refusal to fill out the questionnaire and linguistic barrier.

RESULTS

1307 subjects filled out the survey: 1020 on paper format and 287 via the Internet. About two-thirds of the population recognized a majority of symptoms. However, there was a significant lack of knowledge of complications, especially cardiological and neurological. Suffering from OSAHS, having had higher education, and being under 40 years of age, were factors linked to better awareness of the syndrome. Internet respondents also showed better awareness.

CONCLUSION

Despite encouraging results regarding OSAHS symptoms, the general population showed limited awareness of its complications. Innovative educational campaigns must be organized to inform practitioners and the general public about the disease and raise awareness of its complications.

Assessment of facial pain and headache before and after nasal polyposis surgery with the DyNaChron questionnaire

OBJECTIVES

Facial pain/headache is reported in 16-67% of nasal polyposis (NP) patients. This wide range may be due to differences in assessment methods. The present prospective study assessed facial pain/headache and quality-of-life (QoL) impact before and after NP surgery.

METHODS

Pain was assessed on the DyNaChron self-administered questionnaire in patients undergoing NP surgery, the day before the procedure (V0) and 6 weeks (V1) and 7 months (V2) after. All patients underwent the same nasalization procedure, sparing the middle turbinates when possible. The questionnaire extract comprised 1 item assessing pain, 13 assessing physical impact and 4 assessing psychosocial impact, with responses on visual analog scales (VAS) graded 0 (no discomfort) to 10 (unbearable discomfort).

RESULTS

Sixty-three patients (mean age: 50.6±12.8 years; 32 male [50.8%], 31 female [49.2%]) were included. Thirty-seven patients (58.7%) had history of NP surgery. Fifty-two percent reported moderate to severe pain before surgery, 17.5% at 6 weeks, and 22.2% at 7 months. One-third reported no pain preoperatively, versus a half at 6 weeks and 7 months. Scores for the physical and psychosocial impact of pain were improved after surgery.

CONCLUSION

Headache/facial pain is frequent in patients for whom NP surgery is indicated. Endoscopic surgery relieves the symptom and its physical and psychosocial impacts. However, one-fifth of patients reported residual postoperative pain.

Structure of the lateral mass of the ethmoid by curved stacking of endoturbinal elements

CONTEXT

According to evo-devo theory, the embryonic development of the nasal organ mimics its phylontogenic formation: the lateral masses of the human ethmoid bone develop by curved "onion" stacking of the endoturbinals (the horizontal bone septa of the mammalian olfactory chamber) under the impact of facial and skull-base remodeling, rather than by pneumatization of cavities communicating via ostia.

OBJECTIVES

To assess the frequency of the onion structure on coronal CT.

MATERIAL AND METHODS

Three independent examiners performed a retrospective descriptive study of coronal CT scans taken ahead of septorhinoplasty between June 2010 and December 2012 in adult patients without history of sinonasal surgery.

RESULTS

Fifty patients were included. In the anterior right and left and posterior right ethmoid, an onion arrangement of the endoturbinals was systematically found on at least 1 view, and on 60% of views taking all ethmoid compartments together. Two endoturbinals were generally involved, but a rolling-up of 3 endoturbinals was also observed, significantly more frequently in the posterior compartments (P=0.004 on the right side, P=0.012 on the left).

CONCLUSION

The onion structure of the lateral masses of the ethmoid can be observed on coronal CT scans. This structure confirms evo-devo theory. The ethmoid thus appears fundamentally different from the paranasal sinuses, suggesting that the pathogenesis of nasal polyposis and ethmoidectomy techniques need to be reconsidered.

Nasal or canthal-alar parentheses: A study of the facial base of the nose

OBJECTIVES

The facial implantation of the osseous nasal pyramid corresponds to the piriform aperture, the shape of which is projected on the facial skin in the form of bracket-shaped parentheses. The objective of this study was to compare inter-parenthesis width with subjective visibility on frontal photographs.

MATERIAL AND METHODS

The "patient" group came from a retrospective cohort of photographs taken ahead of septorhinoplasty. The "model" group photographs were collected from the Web or magazines. Nasal parentheses were first judged subjectively as frank or faint. Then, independently, parenthesis width was measured by computer in pixels and converted into millimeters by iris-dependent calibration. Inter-parenthesis width was compared statistically with the frank/faint assessment, according to gender and group.

RESULTS

A total of 113 photographs were included: 46 patients (19 women, 27 men) and 67 models (43 women, 24 men). Sixty-seven of the 113 nasal parentheses appeared frank (59.3%), more frequently in men than women (70.6% vs 50.0%, P=0.02) and in patients than models (69.6% vs 52.2%, P=0.06). Inter-parenthesis width was significantly greater in frank than faint presentations (34.9±3.5mm vs 30.7±3.4mm, P<0.0001), in men than women (35.2±4.1mm vs 31.5±3.1mm, P<0.0001), and in patients than models (34.9±4.0mm vs 32.0±3.6mm, P<0.0001).

CONCLUSION

Frank nasal parentheses correspond to wider facial implantation of the nose.

Sinusology

This paper presents a brief history of the successive anatomical, physiological and pathophysiological concepts about the paranasal sinuses. Sinusology, the science of the paranasal sinuses, is founded on scientific work on the production of nitric oxide (NO) by the sinuses and on the evo-devo theory of their formation. The paranasal sinuses seem to develop after regression of the erythropoietic marrow in the maxillary, frontal and sphenoid bones and its replacement by cavities filled with gas, which escapes into the nasal fossae through the ostium. The sinus epithelium synthesizes NO continuously. The paranasal sinus cavities form a compartmentalized reservoir of NO, which is released discontinuously in boli after an opening of the ostium. Ostium opening can be induced by sound vibration, either internal (humming) or external (an acoustic vibration added to the in-breath). NO plays the role of an "aerocrine" messenger between the upper and lower respiratory tracts, reducing pulmonary vascular resistance and facilitating alveolar oxygen transfer into the bloodstream. Its physiological role in arterial blood oxygenation could be involved in speech and singing or be activated by physiological snoring during sleep. Rhinology, the science of the nose, in which the evo-devo concept distinguishes the respiratory and the olfactory nose, is now backed up by sinusology.

High-frequency nano-optomechanical disk resonators in liquids

Nano- and micromechanical resonators are the subject of research that aims to develop ultrasensitive mass sensors for spectrometry, chemical analysis and biomedical diagnosis. Unfortunately, their merits generally diminish in liquids because of an increased dissipation. The development of faster and lighter miniaturized devices would enable improved performances, provided the dissipation was controlled and novel techniques were available to drive and readout their minute displacement. Here we report a nano-optomechanical approach to this problem using miniature semiconductor disks. These devices combine a mechanical motion at high frequencies (gigahertz and above) with an ultralow mass (picograms) and a moderate dissipation in liquids. We show that high-sensitivity optical measurements allow their Brownian vibrations to be resolved directly, even in the most-dissipative liquids. We investigate their interaction with liquids of arbitrary properties, and analyse measurements in light of new models. Nano-optomechanical disks emerge as probes of rheological information of unprecedented sensitivity and speed, which opens up applications in sensing and fundamental science.

Investigating the utility of in vivo bio-impedance spectroscopy for the assessment of post-ischemic myocardial tissue

Increased myocardial structural heterogeneity in response to ischemic injury following myocardial infarction (MI) is purported as the mechanism of ventricular arrhythmogenesis. Current modalities for in vivo assessment of structural heterogeneity for identification of arrhythmogenic substrate are limited due to the complex nature of the structural microenvironment post-MI. We investigated the utility of in vivo bio-impedance spectroscopy (BIS) in a large post-infarct animal model for differentiation between normal and infarcted tissue. We also investigated the quantitative effects of adipose and collagen on BIS assessment of myocardium. The results indicate that the degree of myocardial injury following chronic post-infarction remodeling could be reliably quantified (performed in triplicates) using BIS. Furthermore, the presence of intramyocardial adipose tissue that develops in conjunction with collagen within the infarct zone had a greater and significant influence on BIS then collagen tissue alone. These preliminary results indicate a potential role of BIS for quantitative assessment and characterization of complex arrhythmogenic substrates in ischemic cardiomyopathy.

All-atom empirical potential for molecular modeling and dynamics studies of proteins

New protein parameters are reported for the all-atom empirical energy function in the CHARMM program. The parameter evaluation was based on a self-consistent approach designed to achieve a balance between the internal (bonding) and interaction (nonbonding) terms of the force field and among the solvent-solvent, solvent-solute, and solute-solute interactions. Optimization of the internal parameters used experimental gas-phase geometries, vibrational spectra, and torsional energy surfaces supplemented with ab initio results. The peptide backbone bonding parameters were optimized with respect to data for N-methylacetamide and the alanine dipeptide. The interaction parameters, particularly the atomic charges, were determined by fitting ab initio interaction energies and geometries of complexes between water and model compounds that represented the backbone and the various side chains. In addition, dipole moments, experimental heats and free energies of vaporization, solvation and sublimation, molecular volumes, and crystal pressures and structures were used in the optimization. The resulting protein parameters were tested by applying them to noncyclic tripeptide crystals, cyclic peptide crystals, and the proteins crambin, bovine pancreatic trypsin inhibitor, and carbonmonoxy myoglobin in vacuo and in crystals. A detailed analysis of the relationship between the alanine dipeptide potential energy surface and calculated protein φ, χ angles was made and used in optimizing the peptide group torsional parameters. The results demonstrate that use of ab initio structural and energetic data by themselves are not sufficient to obtain an adequate backbone representation for peptides and proteins in solution and in crystals. Extensive comparisons between molecular dynamics simulations and experimental data for polypeptides and proteins were performed for both structural and dynamic properties. Energy minimization and dynamics simulations for crystals demonstrate that the latter are needed to obtain meaningful comparisons with experimental crystal structures. The presented parameters, in combination with the previously published CHARMM all-atom parameters for nucleic acids and lipids, provide a consistent set for condensed-phase simulations of a wide variety of molecules of biological interest.

Comprehensive and high-resolution typing of swine leukocyte antigen DQA from genomic DNA and determination of 25 new SLA class II haplotypes

We previously reported the development of genomic-DNA-based high-resolution genotyping methods for SLA-DQB1 and DRB1. Here, we report the successful typing of SLA-DQA using similar methodological principles. We designed a method for comprehensive genotyping of SLA-DQA using intronic sequence information of SLA-DQA exon 2 that we had obtained from 12 animals with different SLA-DQB1 genotypes. We expanded our typing to 76 selected animals with diverse DQB1 and DRB1 genotypes, 140 random animals from 7 pig breeds, and 3 wild boars. This resulted in the identification of 17 DQA alleles with 49 genotypes. Two new alleles were identified from wild boars. Combine with SLA-DQB1, and DRB1 typing results, we identified 34 SLA class II haplotypes including 25 that were previously unreported.

Descriptive results of a prospective cohort study of avian influenza in the Mekong River Delta of Viet Nam

A prospective cohort study of avian influenza infection in poultry flocks was carried out in the Mekong River Delta of Viet Nam between December 2008 and April 2010. Our objectives were to (i) estimate the prevalence and incidence of avian influenza virus infection and (ii) assess the efficacy of H5N1 vaccination programmes as indicated by the presence of H5 antibody in vaccinated and unvaccinated poultry. Real-time PCR and H5 multiplex assays were used to detect the antigen of avian influenza viruses from swab samples. The haemagglutination inhibition test was used to detect H5 antibody. A total of 17 968 swab and 14 878 blood samples were collected from 5476 birds over the study period. The overall incidence rate of influenza type A virus infection was 5 (95% CI 4-7) positive birds per 100 bird-months at risk. The overall incidence rate of H5 virus infection was 0.2 (95% CI 0.1-0.5) positive birds per 100 bird-months at risk. Fifty (95% CI 48-52) birds per 100 tested birds were H5 HI positive in the unvaccinated group compared with 71 (95% CI 69-73) birds per 100 in the vaccinated group. Influenza type A and H5 viruses were circulating in village poultry throughout the study period with no recorded signs of clinical disease. This implies that interventions need to be carried out continuously throughout the year rather than only focusing on the established high-risk periods. Broiler ducks had an incidence rate of influenza H5 virus infection approximately four times greater than that of layer ducks and in-contact species. We conclude that broiler ducks are likely to be the main entry route for H5 virus into poultry flocks in the MRD. Control efforts would benefit from understanding why there is a difference between villages in H5 incidence and developing strategies to provide greater protection to broiler ducks.

Balancing mechanical strength with bioactivity in chitosan-calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes

The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p < 0.01) in cells per scaffold mass vs. AD constructs. Collagen was ∼31% greater (p < 0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4 MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.