Bistable and self-tunable negative-index metamaterial at optical frequencies

We introduce a metamaterial design composed of square plasmonic loops loaded by Kerr nonlinearities that combines enhanced nonlinear response with strong artificial magnetism, ensuring a negative refractive index with bistable and self-tunable response. We verify with full-wave simulations that positive-to-negative switching of refractive index may be obtained with moderate loss. The design of a finite-size metamaterial prism is also presented, supporting at the same frequency, and for the same light intensity, positive or inverted Snell refraction as a function of its previous excitation history.

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.

Ultrabroadband elastic cloaking in thin plates

Control of waves with metamaterials is of great topical interest, and is fueled by rapid progress in broadband acoustic and electromagnetic cloaks. We propose a design for a cloak to control bending waves propagating in isotropic heterogeneous thin plates. This is achieved through homogenization of a multilayered concentric coating filled with piecewise constant isotropic elastic material. Significantly, our cloak displays no phase shift for both backward and forward scattering. To foster experimental efforts, we provide a simplified design of the cloak which is shown to work in a more than two-octave frequency range (30 Hz to 150 Hz) when it consists of 10 layers using only 6 different materials overall. This metamaterial should be easy to manufacture, with potential applications ranging from car industry to anti-earthquake passive systems for smart buildings, depending upon the plate dimensions and wavelengths.

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

17534

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.

The interaction between endothelium-derived relaxing factor (EDRF) and eicosanoids in the regulation of the mesenteric microcirculation

Locally produced eicosanoids and endothelium-derived factors are believed to be the mediators of vascular tone of various vascular beds including the mesentery. Using a small vessel isometric myograph which allows direct measurement of microvascular reactivity, the interaction of eicosanoids and endothelium-derived relaxing factor (EDRF) in regulating vascular tone of mesenteric microcirculation of the rat was characterized. The microvascular response to various vasoactive agents before and after inhibition of prostacyclin production with indomethacin (INDO, 5 microM) and inhibition of EDRF synthesis with N omega-nitro-L-arginine methyl ester (L-NAME, 50 microM) was compared. Analysis of dose-response curves for prostaglandin F2 alpha (PGF2 alpha), U46619, a stable thromboxane analog, and norepinephrine (NE) after pretreatment with INDO demonstrated that inhibition of endogenous eicosanoids significantly attenuated the vasoconstrictor response to PGF2 alpha and U46619 but not to NE. Inhibition of EDRF synthesis with L-NAME potentiated the vasoconstrictor response to PGF2 alpha, U46619, and NE. These results suggest that EDRF acts as the primary mediator of vasodilator tone in the mesenteric microcirculation rather than vasodilator cyclooxygenase products such as prostacyclin. It also appears that the vasoconstrictor action of PGF2 alpha and U46619 may be mediated by a release of an endogenous indomethacin-sensitive factor.

Effect of N-substituted arginine compounds on blood pressure in anesthetized rats

Inhibition of endothelium-dependent relaxation by NG-monomethyl L-arginine (L-NMMA) and its reversal by excess L- but not D-arginine is used to support the hypothesis that the endothelium-derived relaxing factor (EDRF) is generated exclusively from the metabolism of L-arginine. However, in freshly isolated vascular tissues, L-arginine is a poor vasodilator when compared to the N-substituted arginine compound, N alpha-benzoyl L-arginine ethyl ester (BAEE). Here, we show that such N-substituted compounds are potent hypotensive agents in anesthetized rats. In contrast, L-arginine elicits hypotensive effect only at higher concentrations (greater than 100 mg/kg). This effect of L-arginine is not antagonized by L-NMMA. Furthermore, D-arginine, L-homoarginine and L-lysine also have hypotensive effects at these concentrations. Indomethacin treatment partially attenuates the hypotensive effects of the basic amino acids. In contrast, the hypotensive effect of BAEE is antagonized by L-NMMA in a dose-dependent manner and by methylene blue, which is an inhibitor of soluble guanylate cyclase. In addition, substitution at the arginine moiety determines the hypotensive effect. When the amino acid glycine is inserted between the benzoyl group and arginine as in benzoyl-glycine-arginine, significant attenuation of the hypotensive effect is observed. These data demonstrate that compounds such as BAEE generate an EDRF-like agent in vivo and basic amino acids such as L-arginine elicit hypotension at concentrations above 100 mg/kg by mechanisms other than the generation of EDRF.

Platelet activating factor (PAF) and tumor necrosis factor-alpha (TNF alpha) interactions in endotoxemic shock: studies with BN 50739, a novel PAF antagonist

BN 50739, a new PAF receptor antagonist, was tested in vitro and in vivo for its capacity to block PAF, endotoxin and recombinant human tumor necrosis factor-alpha (rTNF)-mediated effects. In vitro, BN 50739 blocked PAF-induced platelet aggregation by 60 to 100% at 0.2-1 x 10(-7) M (P less than .002), respectively. In the conscious rat, pretreatment (30 min) with BN 50739 (n = 5-13) dose-dependently attenuated PAF-induced hypotension (-5 +/- 5 vs. - 43 +/- 2 mm Hg, P less than .01) and shortened the recovery time of mean arterial pressure (22 +/- 13 vs. 325 +/- 46 sec, P less than .01). BN 50739 (10 mg/kg i.p., n = 5-11) prevented endotoxin (14.4 mg/kg) induced-hemoconcentration (54 +/- 1 vs. 46 +/- 1%, P less than .01) and reduced 24-hr mortality (100 vs. 60%, P less than .05). Only partial protection was conveyed by BN 50739 against the hypotensive response to endotoxin (115 +/- 3 vs. 91 +/- 4 mm Hg, P less than .03). Also, BN 50739 attenuated the lipopolysaccharide-induced elevation of plasma thromboxane B2 (21.2 +/- 0.8 vs. 46.7 +/- 11.8 pg/100 microliters, P less than .01) and tumor necrosis factor-alpha (7523 +/- 3983 vs. 26,430 +/- 3541 U/ml, P less than .05), whereas leukopenia and thrombocytopenia remained unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective effect of BN 50739, a new platelet-activating factor antagonist, in endotoxin-treated rabbits

Platelet-activating factor (PAF) has been demonstrated in the circulation and organs of animals exposed to gram negative endotoxins, whereas PAF antagonists have been shown to exhibit some efficacy in modifying the course of endotoxemia. In this study we evaluated BN 50739, a novel specific PAF antagonist, for its capacity to block PAF or lipopolysaccharide endotoxin (LPS)-mediated effects in rabbits. Pretreatment with BN 50739 (3 and 10 mg/kg i.p.) inhibited PAF (500 pmol/kg i.v.)-induced thrombocytopenia, leukopenia and plasma thromboxane B2 elevation in a dose-dependent manner. The inhibitory effect lasted 3.5 to 4.5 hr. BN 50739 (10 mg/kg) prevented the early phase of LPS (50 micrograms/kg i.v.)-induced thrombocytopenia and thromboxane B2 elevation, and reduced the 24-hr mortality rate from 75 to 22% (P less than .05). Post-treatment with BN 50739 increased the 10-hr survival rate from 33 to 87% (P less than .05); however, it had no effect on the 24-hr mortality. BN 50739 did not affect LPS-induced leukopenia or the elevation in plasma tumor necrosis factor. Our data support possible therapeutic efficacy of PAF antagonists in septic shock despite their inability to prevent the generation of tumor necrosis factor.

Pharmacologic profile of BN 50739, a new PAF antagonist in vitro and in vivo

The effect of a new PAF antagonist BN 50739 was studied on PAF-induced [3H]-serotonin release from washed rabbit platelets in vitro and on PAF-induced hypotension in vivo. BN 50739 competitively inhibited PAF-induced [3H]-serotonin release from the platelets in a dose-dependent manner. In the presence of 4, 10 and 50 nM of BN 50739, the concentration of PAF inducing 50% maximal [3H]-serotonin release from the platelets (EC50) increased from 2.15 nM to 5.10, 45.10 and 900 nM, respectively. The IC50 of BN 50739 for PAF (10 nM) induced [3H]-serotonin release was 3.67 nM. Under the same experimental condition, the IC50s of BN 50726, BN 50730, BN 50741, WEB 2086, SRI 63-441 and BN 52021 were 5.40, 4.61, 6.88, 5.98, 40.90 nM and 14.90 microM, respectively. PAF-induced hypotension in conscious rats was also inhibited dose-dependently by i.p. pretreatment of BN 50739 (3 and 10 mg/kg). PAF-induced hypotension was diminished both in magnitude and duration in rats pretreated with BN 50739. These data taken together indicate that BN 50739 is a most potent PAF antagonist in vitro and in vivo.

Effect of N alpha-benzoyl-L-arginine ethyl ester on coronary perfusion pressure in isolated guinea pig heart

N alpha-Benzoyl-L-arginine ethyl ester (BAEE) when compared to L-arginine significantly decreased coronary perfusion pressure of isolated guinea pig heart in a dose dependent and reproducible manner. This effect of BAEE was antagonized by haemoglobin and N-monomethyl L-arginine, both inhibitors of endothelium dependent relaxation. These results support the notion that the mechanism of relaxation elicited by BAEE is due to the generation endothelium dependent relaxing factor (EDRF) like agents.

[Seroimmunological profile of kala-azar in Tunisia]

165 sera of patients suffering from kala-azar were collected before and after treatment (N-methyl glucamine: Glucantime ) and analysed for anti-leishmania antibodies by the counter immunoelectrophoresis and fluorescent antibody techniques. Serum immunoglobulins G, A, M and Complement C4 and C3 were studied as well; and C reactive protein, rheumatoid factor and anti-nuclear, anti-mitochondrial and anti-smooth muscle antibodies were investigated. Before treatment, counter immuno-electrophoresis was positive in 63.88% and immunofluorescent antibody test in 94.6%. The analysis of immunoglobulins has shown an increase of IgG in nearly all cases, an increase of IgM in 78.26% of sera tested. Little change has been noted with IgA. C reactive protein has been found in 87.67% and rheumatoid factor in 76.4% of sera examined. In 4 patients, anti-smooth muscle antibodies have been found at a relatively weak dilution. A decrease of complement C4 has been observed whereas complement C3 was slightly increased. After treatment (2 cures of Glucantime ) counter immunoelectrophoresis was positive in 23.07% of cases whereas immunofluorescent antibody test was still positive in 84.62%. IgG remained increases in the whole cases and IgM in only 43,48%. C reactive protein and rheumatoid factor have been found in 14.81% and 50% of cases respectively. Complement C4 remained low whereas complement C3 showed normal mean value. The relationship between the serological disturbances observed and the prognosis were discussed.

[Hydatid cysts of the lung treated surgically]

Pulmonary echinococcosis is still widespread in Tunisia as in most countries of North Africa. The segment of population affected is young; 198(74%) of 268 patients studied by the authors were less than 30 years old. There were no symptoms in 8% of patients and 92% presented with some complication. The treatment of choice is surgical but conservative pericystectomy was performed in 204 (76%) patients and resection in 64 (24%). Operative mortality was 1.5% and postoperative complications were noted in 8% of patient with an infected cyst. If it is impossible to prevent the disease, the authors recommend early detection, permitting surgical treatment without complications.