Oral bacteria accelerate pancreatic cancer development in mice

OBJECTIVE

Epidemiological studies highlight an association between pancreatic ductal adenocarcinoma (PDAC) and oral carriage of the anaerobic bacterium Porphyromonas gingivalis, a species highly linked to periodontal disease. We analysed the potential for P. gingivalis to promote pancreatic cancer development in an animal model and probed underlying mechanisms.

DESIGN

We tracked P. gingivalis bacterial translocation from the oral cavity to the pancreas following administration to mice. To dissect the role of P. gingivalis in PDAC development, we administered bacteria to a genetically engineered mouse PDAC model consisting of inducible acinar cell expression of mutant Kras (Kras +/LSL-G12D; Ptf1a-CreER, iKC mice). These mice were used to study the cooperative effects of Kras mutation and P. gingivalis on the progression of pancreatic intraepithelial neoplasia (PanIN) to PDAC. The direct effects of P. gingivalis on acinar cells and PDAC cell lines were studied in vitro.

RESULTS

P. gingivalis migrated from the oral cavity to the pancreas in mice and can be detected in human PanIN lesions. Repetitive P. gingivalis administration to wild-type mice induced pancreatic acinar-to-ductal metaplasia (ADM), and altered the composition of the intrapancreatic microbiome. In iKC mice, P. gingivalis accelerated PanIN to PDAC progression. In vitro, P. gingivalis infection induced acinar cell ADM markers SOX9 and CK19, and intracellular bacteria protected PDAC cells from reactive oxygen species-mediated cell death resulting from nutrient stress.

CONCLUSION

Taken together, our findings demonstrate a causal role for P. gingivalis in pancreatic cancer development in mice.

Smoked drug use in patients with TB is associated with higher bacterial burden

BACKGROUND: Smoking of illicit drugs may lead to more rapid TB disease progression or late treatment presentation, yet research on this topic is scant. We examined the association between smoked drug use and bacterial burden among patients newly initiated on drug-susceptible TB (DS-TB) therapy.METHODS: Data from 303 participants initiating DS-TB treatment in the Western Cape Province, South Africa, were analyzed. Smoked drug use was defined as self-reported or biologically verified methamphetamine, methaqualone and/or cannabis use. Proportional hazard and logistic regression models (adjusted for age, sex, HIV status and tobacco use) examined associations between smoked drug use and mycobacterial time to culture positivity (TTP), acid-fast bacilli sputum smear positivity and lung cavitation.RESULTS: People who smoked drugs (PWSD) comprised 54.8% (n = 166) of the cohort. TTP was faster for PWSD (hazard ratio 1.48, 95% CI 1.10-1.97; P = 0.008). Smear positivity was higher among PWSD (OR 2.28, 95% CI 1.22-4.34; P = 0.011). Smoked drug use (OR 1.08, 95% CI 0.62-1.87; P = 0.799) was not associated with increased cavitation.CONCLUSIONS: PWSD had a higher bacterial burden at diagnosis than those who do not smoke drugs. Screening for TB among PWSD in the community may facilitate earlier linkage to TB treatment and reduce community transmission.

Advancing TB research using digitized programmatic data

The use of real-world data from national TB care programs has great potential to answer key research questions in TB control and is now opportune due to increasing digital data collection and storage. We summarize an expert stakeholder workshop conducted on this topic in October 2019, with perspectives from academics, national TB program officers, and data managers. We discuss challenges and opportunities in the use of TB programmatic data for research and describe digital data availability in two large, high TB burden countries, Brazil and South Africa. From this, we posit that with a standardized data collection set, improved data management, and greater collaboration, more TB programmatic data can be used for research with measurable public health impact.

A THz graphene metasurface for polarization selective virus sensing

We propose a novel method to exploit chirality of highly sensitive graphene plasmonic metasurfaces to characterize complex refractive indexes (RI) of viruses by detecting the polarization state of the reflected electric fields in the THz spectrum. A dispersive graphene metasurface is designed to produce chiral surface currents to couple linearly polarized incident fields to circularly polarized reflected fields. The metasurface sensing sensitivity is the result of surface plasmon currents that flow in a chiral fashion with strong intensity due to the underlying geometrical resonance. Consequently, unique polarization states are observed in the far-field with the ellipticity values that change rapidly with the analyte's RI. The determination of bimolecular RI is treated as an inverse problem in which the polarization states of the virus is compared with a pre-calculated calibration model that is obtained by full-wave electromagnetic simulations. We demonstrate the polarization selective sensing method by RI discrimination of three different types of Avian Influenza (AI) viruses including H1N1, H5N2, and H9N2 is possible. Since the proposed virus characterization method only requires determination of the polarization ellipses including its orientation at monochromatic frequency, the required instrumentation is simpler compared to traditional spectroscopic methods which need a broadband frequency scan.

P957Characteristics of atrial tachycardia after mitral surgey via biatrial trans-septal approach using high density mapping system

Background

The biatrial trans-septal approach (BTSa) ameliorates mitral valve (MV) exposure in difficult cases when routine left atriotomy doesnt"t allow it. Main steps are an oblique incision on the right atrium (RA), reaching medially the right pulmonary veins (PV), a septal incision from the fossa ovalis, extended up to reach the first incision, then on the left atrium (LA).

Purpose

We aim to study the arrhythmic burden in this post-surgical context, focusing on atrial tachycardia (AT), to investigate the complexity of several possible circuits.

Methods

All patients (>18yo) with previous MV surgery via BTSa for MV repair or replacement, who underwent ablation of AT from January 2017 to September 2019, were enrolled. Patients ablated for persistent or paroxysmal AF, or with AF during the index procedure were excluded. Patients with associated surgery on other valves or congenital defects, coronary, surgical or percutaneous rhythm interventions weren’t excluded. Electroanatomical mapping was created using 2 different high-density mapping system. Substrate and activation map and radio-frequency (RF) ablation (25-50W, Ablation Index target 400) were realized. Cartographies were analysed to evaluate AT re-entry circuit, critical isthmus (CI) location and characterization, atrial vulnerability. Procedural outcomes (AT termination, sinus rhythm (SR) restoration, anti-arrhythmic drugs (AAD) withdrawal), and peri-procedural complications were also evaluated.

Results

We enrolled 49 patients (median age 57 ± 15), finding a maximum of 5 AT per procedure (2 ± 1). A total of 112 AT were mapped: the majority (72%) were persistent AT, 8,2% common atrial flutter. Cycle length was 314 ± 74 msec, with proximal-distal activation of coronary sinus (78%). A multiple re-entry circuit was observed in 70% of index AT. We identified 152 critical isthmus (maximum 5 per procedure). Only 27,9% of our patients had a single CI; CTI was the most frequent one (n = 37), envolved in 33% of all AT, while BTS scars altogether were envolved in 65% AT. A complete AT circuit was mapped in the RA, the LA and both atria in respectively 49%, 11,5% and 39%AT. The distribution of CIs is shown in figure 1. Biatrial and left AT leads to superior procedure, RF and fluoroscopy duration (p <0,05). SR was restored in 93,4%of patients, requiring a DC shock in 4 cases. Immediate AAD withdrawal was achieved after 41%procedures. No pericardial, oesophageal, vascular or phrenic complication occurred. 4 pace-maker implantations were realized because of 3 interatrial, 2 AV block and a sinus node dysfunction.

Conclusions

AT occurring after a BTSa have a high prevalence of multiple re-entry circuits with multiple critical isthmus. Ablation in this context is feasible and safe but often requires a left atrial access. Mapping of both atria should be considered to identify critical isthmus and tailored ablation strategy.

Abstract Figure 1. Critical Isthmus Distribution

Connectivity of diagnostic technologies: improving surveillance and accelerating tuberculosis elimination

In regard to tuberculosis (TB) and other major global epidemics, the use of new diagnostic tests is increasing dramatically, including in resource-limited countries. Although there has never been as much digital information generated, this data source has not been exploited to its full potential. In this opinion paper, we discuss lessons learned from the global scale-up of these laboratory devices and the pathway to tapping the potential of laboratory-generated information in the field of TB by using connectivity. Responding to the demand for connectivity, innovative third-party players have proposed solutions that have been widely adopted by field users of the Xpert(®) MTB/RIF assay. The experience associated with the utilisation of these systems, which facilitate the monitoring of wide laboratory networks, stressed the need for a more global and comprehensive approach to diagnostic connectivity. In addition to facilitating the reporting of test results, the mobility of digital information allows the sharing of information generated in programme settings. When they become easily accessible, these data can be used to improve patient care, disease surveillance and drug discovery. They should therefore be considered as a public health good. We list several examples of concrete initiatives that should allow data sources to be combined to improve the understanding of the epidemic, support the operational response and, finally, accelerate TB elimination. With the many opportunities that the pooling of data associated with the TB epidemic can provide, pooling of this information at an international level has become an absolute priority.

Effect of Time-Delayed Feedback on the Interaction of a Dimer System with its Environment

In this work, we report modeling of non-Markovian open quantum systems, consisting of an excitonic dimer that displays memory effect due to time delayed interaction with its environment. We, indeed investigate the effect of these time delays on quantum coherence and excitation dynamical behavior in the time domain generally considered for photosynthetic experiments (few hundred femtoseconds). In particular, we show that the coherence is maintained for periods proportional to time delays. Additionally, if delay is taken into account, coupling to the environment can be tuned to lower values, unlike in previous studies. This kind of intriguing effect can, therefore, when generalized to complete systems, permit more control on the experimental parameters, which may lead to more accurate description of the photosynthetic energy transfer functioning and subsequent applications in artificial photovoltaic research.

Plasmonically Enhanced Schottky Photovoltaic Devices

Solar-cells based on Schottky junctions between metals and semiconductors (without or with an intermediate insulator) are among the main possibilities towards economical photovoltaic conversion of the solar energy. This is mainly due to their structural simplicity and hence the ease of their realization. We propose here a new kind of light-harvesting devices using plasmonic nano-antenna gratings, that enhance the absorption of light over a broadband spectrum, and permit the reduction of thickness of the cell dramatically, with efficiency around 15% for 3 micrometers ultra-thin Silicon cell. We show that this technique may provide a new avenue in low cost fabrication of thin-film solar-cells.

Cloaking through cancellation of diffusive wave scattering

A new cloaking mechanism, which makes enclosed objects invisible to diffusive photon density waves, is proposed. First, diffusive scattering from a basic core-shell geometry, which represents the cloaked structure, is studied. The conditions of scattering cancellation in a quasi-static scattering regime are derived. These allow for tailoring the diffusivity constant of the shell enclosing the object so that the fields scattered from the shell and the object cancel each other. This means that the photon flow outside the cloak behaves as if the cloaked object were not present. Diffusive light invisibility may have potential applications in hiding hot spots in infrared thermography or tissue imaging.

Virtual-versus-Real Implantation of Flow Diverters: Clinical Potential and Influence of Vascular Geometry

BACKGROUND AND PURPOSE

Intracranial stents have become extremely important in the endovascular management of complex intracranial aneurysms. Sizing and landing zone predictions are still very challenging steps in the procedure. Virtual stent deployment may help therapeutic planning, device choice, and hemodynamic simulations. We aimed to assess the predictability of our recently developed virtual deployment model by comparing in vivo and virtual stents implanted in a consecutive series of patients presenting with intracranial aneurysms.

MATERIALS AND METHODS

Virtual stents were implanted in patient-specific geometries of intracranial aneurysms treated with the Pipeline Embolization Device. The length and cross-section of virtual and real stents measured with conebeam CT were compared. The influence of vessel geometry modifications occurring during the intervention was analyzed.

RESULTS

The virtual deployment based on pre- and poststent implantation 3D rotational angiography overestimated (underestimated) the device length by 13% ± 11% (-9% ± 5%). These differences were highly correlated (R² = 0.67) with the virtual-versus-real stent radius differences of -6% ± 7% (5% ± 4%) for predictions based on pre- and poststent implantation 3D rotational angiography. These mismatches were due principally to implantation concerns and vessel-shape modifications.

CONCLUSIONS

The recently proposed geometric model was shown to predict accurately the deployment of Pipeline Embolization Devices when the stent radius was well-assessed. However, unpredictable delivery manipulations and variations of vessel geometry occurring during the intervention might impact the stent implantation.

[Impact of transcatheter aortic valve implantation in the treatment of aortic valve disease after previous coronary artery bypass]

INTRODUCTION

Patients with a history of coronary artery bypass and aortic valve disease constitute a high-risk group for conventional redo surgery. The transcatheter aortic valve implantation (TAVI) may be an alternative for high-risk patients. The purpose of this study is to evaluate the impact of TAVI in the treatment of aortic valve disease after previous surgical coronary artery revascularization.

PATIENTS AND METHODS

This is a single-center retrospective, observational study, including 87 patients undergoing surgery for surgical heart valve replacement or TAVI from January 2007 to December 2013.

RESULTS

The introduction of transcatheter aortic valve implantation techniques has doubled the number of redo patients treated for aortic valve disease. From 2010 to 2013, the patients treated by conventional surgery diminished by 30%, with improved postoperative outcomes. This study allowed us to notice differences in patient's in terms of operative risk factors. For the same reasons no comparison was possible between 2 subgroup of patients. Hospital mortality was 6.4% for conventional aortic surgery and 20% for transcatheter aortic valve treatment.

CONCLUSION

Surgery remains the standard treatment for aortic valve disease even in redo patients, but TAVI becomes a very interesting tool as it may represent a tailored approach for our patients.

Reversion of apoptotic resistance of TP53-mutated Burkitt lymphoma B-cells to spindle poisons by exogenous activation of JNK and p38 MAP kinases

Defects in apoptosis are frequently the cause of cancer emergence, as well as cellular resistance to chemotherapy. These phenotypes may be due to mutations of the tumor suppressor TP53 gene. In this study, we examined the effect of various mitotic spindle poisons, including the new isocombretastatin derivative isoNH₂CA-4 (a tubulin-destabilizing molecule, considered to bind to the colchicine site by analogy with combretastatin A-4), on BL (Burkitt lymphoma) cells. We found that resistance to spindle poison-induced apoptosis could be reverted in tumor protein p53 (TP53)-mutated cells by EBV (Epstein Barr virus) infection. This reversion was due to restoration of the intrinsic apoptotic pathway, as assessed by relocation of the pro-apoptotic molecule Bax to mitochondria, loss of mitochondrial integrity and activation of the caspase cascade with PARP (poly ADP ribose polymerase) cleavage. EBV sensitized TP53-mutated BL cells to all spindle poisons tested, including vincristine and taxol, an effect that was systematically downmodulated by pretreatment of cells with inhibitors of p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases. Exogenous activation of p38 and JNK pathways by dihydrosphingosine reverted resistance of TP53-mutated BL cells to spindle poisons. Dihydrosphingosine treatment of TP53-deficient Jurkat and K562 cell lines was also able to induce cell death. We conclude that activation of p38 and JNK pathways may revert resistance of TP53-mutated cells to spindle poisons. This opens new perspectives for developing alternative therapeutic strategies when the TP53 gene is inactivated.

Platonic scattering cancellation for bending waves in a thin plate

We propose an ultra-thin elastic cloak to control the scattering of bending waves in isotropic heterogeneous thin plates. The cloak design makes use of the scattering cancellation technique applied, for the first time, to the biharmonic operator describing the propagation of bending waves in thin plates. We first analyze scattering from hard and soft cylindrical objects in the quasistatic limit, then we prove that the scattering of bending waves from an object in the near and far-field regions can be suppressed significantly by covering it with a suitably designed coating. Beyond camouflaging, these findings may have potential applications in protection of buildings from earthquakes and isolating structures from vibrations in the motor vehicle industry.

Tunable graphene antennas for selective enhancement of THz-emission

In this paper, we will introduce THz graphene antennas that strongly enhance the emission rate of quantum systems at specific frequencies. The tunability of these antennas can be used to selectively enhance individual spectral features. We will show as an example that any weak transition in the spectrum of coronene can become the dominant contribution. This selective and tunable enhancement establishes a new class of graphene-based THz devices, which will find applications in sensors, novel light sources, spectroscopy, and quantum communication devices.

Energy partition at the collapse of spherical cavitation bubbles

Spherically collapsing cavitation bubbles produce a shock wave followed by a rebound bubble. Here we present a systematic investigation of the energy partition between the rebound and the shock. Highly spherical cavitation bubbles are produced in microgravity, which suppresses the buoyant pressure gradient that otherwise deteriorates the sphericity of the bubbles. We measure the radius of the rebound bubble and estimate the shock energy as a function of the initial bubble radius (2-5.6mm) and the liquid pressure (10-80kPa). Those measurements uncover a systematic pressure dependence of the energy partition between rebound and shock. We demonstrate that these observations agree with a physical model relying on a first-order approximation of the liquid compressibility and an adiabatic treatment of the noncondensable gas inside the bubble. Using this model we find that the energy partition between rebound and shock is dictated by a single nondimensional parameter ξ=Δpγ6/[p(g0)1/γ(ρc2)1-1/γ], where Δp=p∞ - pv is the driving pressure, p∞ is the static pressure in the liquid, pv is the vapor pressure, pg0 is the pressure of the noncondensable gas at the maximal bubble radius, γ is the adiabatic index of the noncondensable gas, ρ is the liquid density, and c is the speed of sound in the liquid.

Scattering cancellation of the magnetic dipole field from macroscopic spheres

Based on the scattering cancellation technique we suggest a cloak that allows to conceal macroscopic objects, i.e. objects with an optical size comparable to wavelengths in the visible and whose scattering response is dominated by a magnetic dipole contribution. The key idea in our approach is to use a shell of polaritonic spheres around the object to be cloaked. These spheres exhibit an artificial magnetism. In a systematic investigation, where we progressively increase the complexity of the considered structure, we devise the requirements imposed on the shell and outline how it can be implemented with natural available materials.

Analytical approximations for the collapse of an empty spherical bubble

The Rayleigh equation 3/2R+RR+pρ(-1)=0 with initial conditions R(0)=R(0), R(0)=0 models the collapse of an empty spherical bubble of radius R(T) in an ideal, infinite liquid with far-field pressure p and density ρ. The solution for r≡R/R(0) as a function of time t≡T/T(c), where R(T(c))≡0, is independent of R(0), p, and ρ. While no closed-form expression for r(t) is known, we find that r(0)(t)=(1-t(2))(2/5) approximates r(t) with an error below 1%. A systematic development in orders of t(2) further yields the 0.001% approximation r(*)(t)=r(0)(t)[1-a(1)Li(2.21)(t(2))], where a(1)≈-0.01832099 is a constant and Li is the polylogarithm. The usefulness of these approximations is demonstrated by comparison to high-precision cavitation data obtained in microgravity.

Universal scaling law for jets of collapsing bubbles

Cavitation bubbles collapsing and rebounding in a pressure gradient ∇p form a "microjet" enveloped by a "vapor jet." This Letter presents unprecedented observations of the vapor jets formed in a uniform gravity-induced ∇p, modulated aboard parabolic flights. The data uncover that the normalized jet volume is independent of the liquid density and viscosity and proportional to ζ ≡ |∇p|R(0)/Δp, where R(0) the maximal bubble radius and Δp is the driving pressure. A derivation inspired by "Kelvin-Blake" considerations confirms this law and reveals its negligible dependence of surface tension. We further conjecture that the jet only pierces the bubble boundary if ζ ≳ 4 × 10(-4).

Luminescence from hydrodynamic cavitation

The majority of the research on cavitation luminescence has focused on the sonoluminescence or chemiluminescence generated by cavitation induced through ultrasound, with a lesser body of work on the luminescence induced by laser- or spark-induced cavitation. In such circumstances, the cavitation is generated in liquids where, on the broad scale, there is usually assumed to be no net liquid flow (although of course there are small-scale flows as a result of the cavitation itself, through radiation forces, streaming, microstreaming and turbulence). Little attention has been paid to the luminescence that accompanies (undesirable) cavitation in pumps and turbines or in marine propellers. In the present study, the sonoluminescence specific to air/water vapour bubbles, collapsing within a cavitation tunnel, is addressed. The particular case of leading edge cavitation over a two-dimensional hydrofoil is considered in detail. Hence, strong instabilities develop, causing the attached cavity to shed large clouds of micro bubbles. The spatial and temporal properties of the emitted luminescence were studied using an intensified charge coupled device video camera and a photomultiplier (PM). The light emission was found to extend downstream from the region of cavity closure, to the region where the travelling vortices collapse. Examination of the PM signal on short time scales showed that the emitted luminescence consisted of relatively intense flashes of short duration (as with other forms of luminescence). Individual flashes were often found to be clustered in time. Over longer time scales, clear evidence of periodicity was found in the PM signals. Further analysis showed that bursts of light were being emitted at the Strouhal frequency (for the shedding of transcient cavities).

Negative refraction, surface modes, and superlensing effect via homogenization near resonances for a finite array of split-ring resonators

We present a theoretical and numerical analysis of liquid surface waves (LSWs) localized at the boundary of a phononic crystal consisting of split-ring resonators (SRRs). We first derive the homogenized parameters of the fluid-filled structure using a three-scale asymptotic expansion in the linearized Navier-Stokes equations. In the limit when the wavelength of the LSW is much larger than the typical heterogeneity size of the phononic crystal, we show that it behaves as an artificial fluid with an anisotropic effective shear modulus and a dispersive effective-mass density. We then analyze dispersion diagrams associated with LSW propagating within an infinite array of SRR, for which eigensolutions are sought in the form of Floquet-Bloch waves. The main emphasis is given to the study of localized modes within such a periodic fluid-filled structure and to the control of low-frequency stop bands associated with resonances of SRRs. Considering a macrocell, we are able to compute the dispersion of LSW supported by a semi-infinite phononic crystal of SRRs. We find that the dispersion of this evanescent mode nearly sits within the first stop band of the doubly periodic structure. We further discover that it is linked to the frequency at which the effective-mass density of the homogenized phononic crystal becomes negative. We demonstrate that this surface mode displays the hallmarks of all-angle negative refraction and it leads to a superlensing effect. Last, we note that our homogenization results for the velocity potential can be applied mutatis mutandis to designs of electromagnetic and acoustic superlenses for transverse electric waves propagating in arrays of infinite conducting SRRs and antiplane shear waves in arrays of cracks shaped as SRRs.

Development of a pilot-scale 1 for Legionella elimination in biofilm in hot water network: heat shock treatment evaluation

AIMS

(i) To develop an analytical tool in order to evaluate the effectiveness of anti-Legionella treatment in biofilm and (ii) study the fate of Legionella populations in water and biofilm after applying a heat shock treatment.

METHODS AND RESULTS

A pilot-scale unit simulating a hot water system was built and designed by the Scientific and Technical Building Centre (CSTB, France). At the end of the contamination period, a stable cultivable Legionella spp. concentration of 5x10(5) CFU l(-1) was obtained. Two heat shock treatments (70 degrees C for 30 min) were applied. The results showed that the first treatment had a transitional effect on the abatement of Legionella concentrations, while the second treatment had no detectable effect on Legionella populations in water and biofilm. The DAPI (4',6'-diamidino-2-phenylindole), Legionella PCR and GVPC (glycocolle vancomycin pyrophosphate cycloheximide) counts measured in the dead leg water of the Test Loop were 1, 2 and 2 log units higher than results found in the Test Loop water. Moreover, Legionella spp. count in tap water was about 10(4) GU l(-1). These analyses revealed that they are responsible for the rapid recolonization as well as the uncomplete destroyed biofilm. In addition, a resistance test was conducted and showed that Legionella in the second heat shock treatment was not thermo-resistant but thermo-acclimated.

CONCLUSION

Thermal disinfection does not seem to be efficient enough to eliminate Legionella when it is used as a curative treatment.

SIGNIFICANCE AND IMPACT OF THE STUDY

This work could help water managers for a better management of water network and for a better control of Legionella.

Methodologies to assess blood flow in cerebral aneurysms: current state of research and perspectives

With intracranial aneurysms disease bringing a weakened arterial wall segment to initiate, grow and potentially rupture an aneurysm, current understanding of vessel wall biology perceives the disease to follow the path of a dynamic evolution and increasingly recognizes blood flow as being one of the main stakeholders driving the process. Although currently mostly morphological information is used to decide on whether or not to treat a yet unruptured aneurysm, among other factors, knowledge of blood flow parameters may provide an advanced understanding of the mechanisms leading to further aneurismal growth and potential rupture. Flow patterns, velocities, pressure and their derived quantifications, such as shear and vorticity, are today accessible by direct measurements or can be calculated through computation. This paper reviews and puts into perspective current experimental methodologies and numerical approaches available for such purposes. In our view, the combination of current medical imaging standards, numerical simulation methods and endovascular treatment methods allow for thinking that flow conditions govern more than any other factor fate and treatment in cerebral aneurysms. Approaching aneurysms from this perspective improves understanding, and while requiring a personalized aneurysm management by flow assessment and flow correction, if indicated.

Broadband cylindrical acoustic cloak for linear surface waves in a fluid

We describe the first practical realization of a cylindrical cloak for linear surface liquid waves. This structured metamaterial bends surface waves radiated by a closely located acoustic source over a finite interval of Hertz frequencies. We demonstrate theoretically its unique mechanism using homogenization theory: the cloak behaves as an effective anisotropic fluid characterized by a diagonal stress tensor in a cylindrical basis. A low azimuthal viscosity is achieved, where the fluid flows most rapidly. Numerical simulations demonstrate that the homogenized cloak behaves like the actual structured cloak. We experimentally analyze the decreased backscattering of a fluid with low viscosity and finite density (methoxynonafluorobutane) from a cylindrical rigid obstacle surrounded by the cloak when it is located a couple of wavelengths away from the acoustic source.

Thinking in three dimensions: a web-based algorithm to aid the interpretation of tuberculin skin test results

BACKGROUND

The tuberculin skin test (TST) is the most widely used test for detecting tuberculosis (TB) infection. Accurate interpretation of TST requires consideration of three dimensions-the size of the skin reaction, the positive predictive value (PPV) and risk of disease.

METHODS

We developed a web-based algorithm incorporating epidemiological, medical and radiographic risk factors to help in the interpretation of positive TST results in adults (http://www.meakins.mcgill.ca/meakins/NEW TST Calculator/homeE.htm). We used summary estimates from published reviews on the prevalence of latent TB infection, the likelihood of false-positive TST and risk of active TB disease.

RESULTS

The algorithm calculations show that the most important determinants of risk of active disease are the presence of medical and radiographic risk factors, while the size of the reaction is of modest importance. In persons who have received bacille Calmette-Guérin vaccination after infancy, the algorithm calculations show that the PPV will be low. In such persons, the risk of disease is predicted to be very low, unless there are medical or radiographic risk factors that increase the risk of reactivation.

CONCLUSIONS

Our web-based algorithm can generate clinically useful estimates of the annual and cumulative lifetime risk of developing TB in adults with a positive TST.

Achieving invisibility over a finite range of frequencies

We analyze cloaking of transverse electric (TE) fields through homogenization of radially symmetric metallic structures. The two-dimensional circular cloak consists of concentric layers cut into a large number of small infinitely conducting sectors which is equivalent to a highly anisotropic permittivity. We find that a wave radiated by a magnetic line current source located a couple of wavelengths away from the cloak is almost unperturbed in magnitude but not in phase. Our structured cloak is shown to work for different wavelengths provided they are ten times larger than the outermost sectors.

Analytical and numerical analysis of lensing effect for linear surface water waves through a square array of nearly touching rigid square cylinders

This paper describes transport properties of linear water waves propagating within a square array of fixed square cylinders. The main focus is on achieving the conditions for all-angle-negative-refraction (AANR) thanks to anomalous dispersion in fluid-filled periodic structures. Of particular interest are two limit cases when either the edges or the vertices of the cylinders come close to touching. In the former case, the array can be approximated by a lattice of thin water channels (for which dispersion curves are given in closed form and thus frequencies at which AANR occurs) whereas in the latter case, the array behaves as a checkerboard with cells consisting either of water tanks or rigid cylinders (for which standing modes are given in closed form). The tools of choice for the present analysis are, on the one hand, the finite element method which solves numerically spectral problems in periodic media, and on the other hand, a two-scale asymptotic method which provides estimates of dispersion curves and associated eigenfields through a lattice approximation (namely thin water channels between rigid cylinders). Simple duality correspondences are found based on fourfold symmetry of square water checkerboards that allow us to get some insight into their spectra. Last, some numerical evidence is provided for water waves focusing with no astigmatism through such arrays, when they are of finite extent.

Oestradiol inhibition of vascular myointimal proliferation following immune, chemical and mechanical injury

The lower incidence of coronary artery disease in premenopausal women and in postmenopausal women treated with oestrogen supports the hypothesis that oestrogen protects the vasculature from injuries or from responding to injuries with arteriosclerosis. The mechanism remains unknown, although currently the most frequent suggestion is that oestrogen induces beneficial quantitative and qualitative changes in serum lipoprotein concentrations. We studied other mechanisms and in particular the direct effects of 17 beta-oestradiol on vascular smooth muscle and the endothelium. Our focus has been on the vascular response to injury by myointimal and medial thickening, leading to narrowing or occlusion of the vessel. This is frequently seen in coronary arteries within months following angioplasty and a few years following cardiac transplantation. We find that oestradiol treatment protects and reduces the vascular response to injury in three in vivo and one in vitro models: (1) in the rabbit cardiac allograft where oestrogen inhibits accelerated graft atherosclerosis; (2) in monocrotaline- or hypoxia-induced pulmonary hypotension in the rat, where oestrogen attenuates pulmonary artery pressure, right ventricular hypertrophy and medial thickening of the pulmonary artery; (3) oestrogen protects against balloon injury in rabbit aorta; and (4) it inhibits smooth muscle cell proliferation in the porcine left anterior descending coronary artery.

False-positive tuberculin skin tests: what is the absolute effect of BCG and non-tuberculous mycobacteria?

BACKGROUND

Despite certain drawbacks, the tuberculin skin test (TST) remains in widespread use. Important advantages of the TST are its low cost, simplicity and interpretation based on extensive published literature. However, TST specificity is reduced by bacille Calmette-Guérin (BCG) vaccination and exposure to non-tuberculous mycobacteria (NTM).

METHODS

To estimate TST specificity, we reviewed the published literature since 1966 regarding the effect of BCG vaccination and NTM infection on TST. Studies selected included healthy subjects with documented BCG vaccination status, including age at vaccination. Studies of NTM effect had used standardised NTM antigens in healthy subjects.

RESULTS

In 24 studies involving 240,203 subjects BCG-vaccinated as infants, 20,406 (8.5%) had a TST of 10+ mm attributable to BCG, but only 56/5639 (1%) were TST-positive if tested > or =10 years after BCG. In 12 studies of 12,728 subjects vaccinated after their first birthday, 5314 (41.8%) had a false-positive TST of 10+ mm, and 191/898 (21.2%) after 10 years. Type of tuberculin test did not modify these results. In 18 studies involving 1,169,105 subjects, the absolute prevalence of false-positive TST from NTM cross-reactivity ranged from 0.1% to 2.3% in different regions.

CONCLUSIONS

The effect on TST of BCG received in infancy is minimal, especially > or =10 years after vaccination. BCG received after infancy produces more frequent, more persistent and larger TST reactions. NTM is not a clinically important cause of false-positive TST, except in populations with a high prevalence of NTM sensitisation and a very low prevalence of TB infection.

Cavitation bubble dynamics inside liquid drops in microgravity

We studied spark-generated cavitation bubbles inside water drops produced in microgravity. High-speed visualizations disclosed unique effects of the spherical and nearly isolated liquid volume. In particular, (1) toroidally collapsing bubbles generate two liquid jets escaping from the drop, and the "splash jet" discloses a remarkable broadening. (2) Shock waves induce a strong form of secondary cavitation due to the particular shock wave confinement. This feature offers a novel way to estimate integral shock wave energies in isolated volumes. (3) Bubble lifetimes in drops are shorter than in extended volumes in remarkable agreement with herein derived corrective terms for the Rayleigh-Plesset equation.

The role of FDG-PET in low-grade non-Hodgkin lymphoma (NHL): Impact of histology

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Background: FDG-PET scan was proved important diagnostic and prognostic tool in patients with aggressive (NHL). The objective of this study is to investigate the correlation between the histology subtype in low-grade NHL and the sensitivity of the FDG-PET. Methods: We included all patients who presented to our institution during the period from April 2001 till April 2004 and underwent staging evaluation by FDG-PET during the course of their disease. All patients had histologically confirmed low-grade NHL. Patients with history of active malignancy, other than NHL, within the last five years were excluded. Correlation was made with the CT-scan findings. Results: 53 patients were included. Age (range 30–82, median 54), 57% of them were male. 34 patients had follicular lymphoma (FL), 9 patients had marginal zone lymphoma (MZL), and 10 patients had small lymphocytic lymphoma (SLL). 24/34 patients with FL underwent FDG-PET during the initial evaluation of their disease, and 10/34 patients underwent FDG-PET as part of their restaging assessment. 33 patients had true positive FDG-PET findings when compared to CT-scan results. One patient had negative FDG-PET with CT-scan findings suggestive of pathologic lymphadenopathy (sensitivity 97%). The highest SUV was in the range of 3.5–15 (median = 7). 8/9 patients with MZL had true positive FDG-PET findings and one had false negative FDG-PET result (sensitivity 89%). The highest SUV was in the range of 2–6.30 (median 2.6). Among the ten patients with SLL, 5 had FDG-PET during the initial evaluation and 8 patients during re-staging workup. 13 FDG-PET results were available for analysis. 5 cases were false negative, 1 case was false positive, 5 cases were true positive, and 2 cases were true negative (sensitivity 50%). The highest SUV was in the range of 1.8–6.2 (median of 2.5). Conclusion: Histology in low-grade NHL has a major impact on the sensitivity of the FDG-PET imaging results. Whereas it is a highly sensitive diagnostic method in patients with FL, and to a lesser degree in patients with MZL, it has poor sensitivity in patients with SLL.

No significant financial relationships to disclose.

Eph and ephrin expression in normal placental development and preeclampsia

Eph receptors and their ephrin ligands play a fundamental role in embryogenesis. Their functions include cell targeting and angiogenesis. In placental development, trophoblasts migrate and invade maternal tissue and spiral arteries, where they play a role in both anchoring the placenta to the uterus and increasing blood flow to the developing fetus (interstitial and endovascular invasions). We investigated the cellular distribution and expression patterns of representative Eph and ephrin RNA and protein in an effort to identify the molecules involved in trophoblast migration during normal placental development and placental pathologies. We found ephrin-A1 expressed exclusively in the invasive extravillous trophoblast (EVT) cell lineage. We therefore proceeded to investigate ephrin-A1 in placental pathologies with defects in EVT invasion. In preeclampsia, where trophoblast invasion is shallow, we observed ephrin-A1 expression similar to normal placenta. Furthermore, in initial experiments on the deeply invading trophoblasts of placenta accreta, which lacks decidua, ephrin-A1 is found to be expressed highly in extravillous trophoblasts that have invaded the myometrium. In addition, we found the prototype ephrin-A1 receptor, EphA2, localized in several placental cell types. EphB4 and ephrin-B2 molecules, which have specific expression patterns during artery and vein development, respectively, were also expressed in the placenta. The cell specific distribution of ephrin-A1 suggests that it may play a role in targeting and migration of trophoblasts, and in the vascular remodeling induced by the invading extravillous trophoblasts. Failure of ephrin-A1 expression is unlikely to be the primary cause in defective migration of trophoblasts observed in preeclampsia. Specific roles for other Eph and ephrin proteins remain to be investigated.

Successful pregnancy following replacement of embryos previously refrozen at blastocyst stage: case report

We present the first reported clinical pregnancy following transfer of embryos that had been subjected to two freeze-thaw cycles: the first at day 3 after insemination, and the second after culturing to the blastocyst stage. A 25-year-old woman undergoing IVF treatment for male factor infertility opted for intracytoplasmic sperm injection (ICSI). ICSI treatment resulted in the successful production of 19 early cleavage embryos, all of which were frozen. After thawing, the embryos were cultured to the blastocyst stage. Thereafter, the blastocysts were refrozen and again thawed prior to embryo transfer. Embryos surviving a day 3 freeze-thaw cycle developed to the blastocyst stage and survived the second freeze-thaw cycle. Successful clinical pregnancy resulted following two sequential freeze-thaw cycles. This finding shows that it is possible to refreeze supernumerary blastocysts for subsequent transfer.

Heliox tolerance in spontaneously breathing neonates with bronchopulmonary dysplasia

The use of a gas mixture in which helium is substituted for nitrogen allows a decrease in pulmonary resistances and in resistive work of breathing. This treatment might allow a reduction in energy expenditure in infants with bronchopulmonary dysplasia (BPD) and spare calories for growth. In a preliminary study designed to assess tolerance to Heliox(R), 4 infants with BPD and 4 controls were studied firstly when breathing air and secondly when breathing Heliox(R), at 10, 20 and 30 min exposure (T10, T20, T30). The following parameters were recorded: respiratory and cardiac rates, room (RT) and skin temperatures (ST) and transcutaneous (Tc) blood gases. When breathing air, TcPO2 was normal in the two groups (mean +/- SEM: 70 +/- 4 mm Hg in BPD vs. 78 +/-4 in controls). TcPCO2 was higher in the BPD group (41 +/- 2 vs. 35 +/- 1 mm Hg in controls; p = 0.028). Spontaneously breathing Heliox had immediate consequences such as wakening, crying, decrease in ST and hypoxia. Hypoxia was more serious and more rapid in the BPD group. At the 10-min exposure, mean TcPO2 was 39 +/- 4 mm Hg in BPD vs. 69 +/- 7 in controls (p = 0.042). Hypoxia was immediately corrected when breathing room air. TcPCO2 was unchanged in both groups.

Frequency of human A gamma 75Thr globin chain in a population from Tunisia

Cord blood samples, collected at Sousse and Monastir, from Tunisian newborns were focused on a thin layer of agarose in order to detect the carriers of the A gamma 75Thr chain (A gamma chain bearing a replacement Ile-->Thr at position 75). Nineteen individuals (10%) were positive for this variant. The frequency of the A gamma 75Thr gene in the Tunisian population (0.050) is compared with that of various ethnic populations.

Intracytoplasmic sperm injection pregnancy with trisomy 20p and monosomy 22q in a newborn resulting from a balanced paternal translocation

In infertile men who carry a balanced reciprocal translocation, intracytoplasmic sperm injection (ICSI) may induce a pregnancy with an abnormal karyotype. This report describes a previously unreported paternal reciprocal translocation leading to a chromosomally unbalanced ICSI pregnancy. The triplet pregnancy resulted in 1 normal girl, 1 physically normal boy with the same balanced paternal translocation, and a severely malformed boy with trisomy 20p and monosomy 22q who died in the neonatal period.

Intermediate-dose intravenous melphalan and blood stem cells mobilized with sequential GM+G-CSF or G-CSF alone to treat AL (amyloid light chain) amyloidosis

AL amyloidosis patients ineligible for dose-intensive melphalan (200 mg/m2) were enrolled on a phase 11 trial to be treated with two cycles of intermediate-dose melphalan (IDM 100 mg/m2) and mobilized blood stem cells (BSC). For mobilization patients were randomized to either GM-CSF 250 microg/m2 for 3 d followed by G-CSF 10 microg/ kg for 3 d (GM+G), or G-CSF 10 microg/kg for 6 d (G-alone), with leukaphereses on days 5, 6 and 7. To minimize morbidity, we planned to support each cycle with 3 5 x 106 CD34+ cells/kg and had a collection target of 7 x 10(6) CD34+ cells/kg. Those who did not achieve the target were treated with one cycle of IDM. 30 patients, a median of 62 years old and 7 months from diagnosis, were enrolled. Both mobilization regimens were generally well tolerated, and similar in terms of CD34+ cells and CFU-GM collected, but only 6/28 patients achieved the collection target (GM+G four, G-alone two). Despite a 19% incidence of grade 4 toxicities, IDM therapy was well tolerated. At a median follow-up of 24 months (19-36) 57% of patients had survived, 17% with durable complete haematological responses and 40% with improved or stable amyloid organ involvement, including 3/9 patients with predominant cardiac amyloid who are alive 2-3 years after treatment. The 100 d mortality was 20%. In conclusion, no definitive differences were identified between the mobilization regimens and IDM was an active regimen in AL for selected patients.