Signatures of the Optical Stark Effect on Entangled Photon Pairs from Resonantly Pumped Quantum Dots.

Two-photon resonant excitation of the biexciton-exciton cascade in a quantum dot generates highly polarization-entangled photon pairs in a near-deterministic way. However, the ultimate level of achievable entanglement is still debated. Here, we observe the impact of the laser-induced ac-Stark effect on the quantum dot emission spectra and on entanglement. For increasing pulse-duration-to-lifetime ratios and pump powers, decreasing values of concurrence are recorded. Nonetheless, additional contributions are still required to fully account for the observed below-unity concurrence.

Encephalomyocarditis virus 2A protein is required for viral pathogenesis and inhibition of apoptosis.

The encephalomyocarditis virus (EMCV), a Picornaviridae virus, has a wide host spectrum and can cause various diseases. EMCV virulence factors, however, are as yet ill defined. Here, we demonstrate that the EMCV 2A protein is essential for the pathogenesis of EMCV. Infection of mice with the B279/95 strain of EMCV resulted in acute fatal disease, while the clone C9, derived by serial in vitro passage of the B279/95 strain, was avirulent. C9 harbored a large deletion in the gene encoding the 2A protein. This deletion was incorporated into the cDNA of a pathogenic EMCV1.26 strain. The new virus, EMCV1.26Δ2A, was capable of replicating in vitro, albeit more slowly than EMCV1.26. Only mice inoculated with EMCV1.26 triggered death within a few days. Mice infected with EMCV1.26Δ2A did not exhibit clinical signs, and histopathological analyses showed no damage in the central nervous system, unlike EMCV1.26-infected mice. In vitro, EMCV1.26Δ2A presented a defect in viral particle release correlating with prolonged cell viability. Unlike EMCV1.26, which induced cytopathic cell death, EMCV1.26Δ2A induced apoptosis via caspase 3 activation. This strongly suggests that the 2A protein is required for inhibition of apoptosis during EMCV infection. All together, our data indicate that the EMCV 2A protein is important for the virus in counteracting host defenses, since Δ2A viruses were no longer pathogenic and were unable to inhibit apoptosis in vitro.

[Uterine and ovarian necrosis following embolisation of the uterine arteries for postpartum haemorrhagia]. / Nécrose utérine et ovarienne après embolisation des artères utérines pour hémorragie de la délivrance.

We report here the case of a young woman who presented with pain, fever and apparent cutaneous sub ischaemia following embolisation of the uterine arteries for postpartum haemorrhagia. This embolisation was carried out by bilateral selective catheterism of the uterine arteries using 45 to 150 micron polyvinyl alcohol particles. Investigative laparotomy was decided in view of the persistence of the symptoms, and the patient underwent hysterectomy with ablation of the right adnexa to treat uterine necrosis and adnexal atrophy. Because of the information that we have actually, we can explain that this complication is linked with the use of polyvinyl alcohol small size particles. The migration of those embolisation agents might be responsible for obliteration of a large number of distal vessels. Those embolisation agents must, because of recommendation for good practice published in 2004, be reserved to exceptional cases to minimize the complication of embolisation.

Burst-fractures and cementoplasty.

Percutaneous acrylic cement vertebroplasty is known for its pain-relieving effect in spinal tumors and recently in osteoporotic vertebral collapse. To our knowledge no study has been published reporting the treatment of acute high energy post-traumatic fracture (mainly single burst fracture) by vertebroplasty. Our purpose was to evaluate the technical feasibility of the cement injection at this acute phase, assess its the impact on the pain and monitor spinal stability, by quantifying potential kyphosis modification. Twelve patients with relative contraindication of the orthopaedic treatment were treated by early injection after the trauma for an A type fracture of the Magerl classification, without neurological sign. Patients surveys revealed a significant pain reduction within the first day. Half of them reduced the kyphosis angle, and the anterior height vertebral body significantly improved after the vertebroplasty. The mean reduction in the kyphosis angle was 8. No complication occurred except one extravertebral asymptomatic leak, with secondary increase of the kyphosis. Vertebroplasty performed in reduction position may allow a complete stabilization without pain and furthermore can reduce the kyphosis angle.

Aphid transmission of a potyvirus depends on suitability of the helper component and the N terminus of the coat protein.

The present study investigates the specificity of potyviruses for aphid species. Two potyviruses differing in their host range were used: Zucchini yellow mosaic virus (ZYMV) mainly infecting cucurbits and Turnip mosaic virus (TuMV) mainly infecting crucifers. Two sets of aphids species were used as vectors, one polyphagous (Myzus persicae and Aphis gossypii) and the other from crucifers (Brevicoryne brassicae and Lipaphis erysimi). Evidence is provided that the specificity between a vector and a potyvirus depends either on the affinity between the aphid species and the helper component (HC) protein used or on the affinity between the HC and the virions. The difference between the two potyviruses cannot be attributed to the DAG domain which is unaltered in both N termini of the CP. Therefore, a ZYMV full length clone served to exchange a fragment encoding for the N terminus of the ZYMV CP by that of TuMV. This partial exchange in the ZYMV CP, allowed the TuMV HC to transmit the chimeric virus but not the wild type ZYMV. The significance of the N terminus context of the CP in the specificity for the HC is discussed.

Comparison of newly isolated cuticular protein genes from six aphid species.

This paper reports on the first aphids' cuticular proteins. One gene (Mpcp1) was obtained by screening a cDNA library of Myzus persicae with antibodies to a lepidopteran cuticle protein. MpCP1 presents a putative signal peptide, a central extended R&R domain, flanked by N- and C-terminal repeats of alanine, tyrosine and proline. The mRNA of Mpcp1 could be detected in a larval and in adult stages. Primers based on Mpcp1 allowed isolating and comparing cuticle protein genes from five aphid species, but not from whitefly or thrips. Comparison revealed a high degree of similarity. Data from this paper suggest that this cuticle protein family is typical and predominant to aphids. The conformation of these cuticle proteins and the significance on particular properties of aphid cuticle is discussed.

[Diagnostic accuracy of the percutaneous spinal biopsy. Optimization of the technique]. / Efficience diagnostique des biopsies discovertébrales percutanées. Optimisation de la technique.

Between 1992 and 1999, 210 percutaneous biopsies of the spine were performed in our department of neuroradiology. The purpose of this retrospective study was to determinate the diagnostic accuracy of the procedure and to discuss the technical points that might improve its accuracy. An accurate diagnosis was obtained in 72% of the spondylodiscitis and in 80% of the tumoral lesions (88% of metastatic lesions and 68% of primary tumors). These results have been compared with the other results of the literature. There was no significant difference of accuracy between CT and fluoroscopic guided biopsies. On the other hand, the type of needle and the multiplicity of samples for bacteriological and histologic studies improve the diagnostic accuracy.

Bone reactions to nacre injected percutaneously into the vertebrae of sheep.

We have studied the osteogenic effects of nacre (mother of pearl) placed in experimental cavities prepared in the lumbar vertebrae of sheep. Some of cavities were filled with nacre, some with PMMA, and some were left empty. The vertebrae were removed 1, 8, 12 weeks after surgery, and assessed histologically and morphometrically. The nacre particles in the bone cavity and the surrounding intertrabecular spaces gradually dissolved beginning at 8 weeks after surgery. There were layers of newly formed bone, both woven and lamellar, in various stages of maturation in contact with or adjacent to the dissolving nacre. Quantitative assessment of the activation of bone formation adjacent to the cavities filled with nacre indicated significant activation of bone formation, which continued until week 12. There was also increased mineralization of the host bone at this time. There was no new bone formation in the empty cavities, or in those filled with PMMA. PMMA also caused necrosis of surrounding bone cells with a change in bone architecture and significant reductions in bone formation and mineralization. This study demonstrates that nacre stimulates bone-forming cells in vertebrae and appears to result in new bone formation.

A model for evaluating injectable bone replacements in the vertebrae of sheep: radiological and histological study.

We developed a bone-defect model in the vertebrae of sheep. Forty four cavities were prepared in the upper lumbar vertebrae of 11 sheep using a biopsy trocar via a posterior-lateral extracanal percutaneous route and the location was monitored by radiology with a brilliance amplifier. The cavities were 3 mm in diameter. The histological study was performed on 15 cavities which were left empty to give reference data for the model. Histological and histomorphometry results showed that 67% of the surface area of the empty cavities was still empty 3 months after their preparation. Thus, the natural regenerative capacity of vertebral trabecular bone is limited. We performed preliminary percutaneous injections of polymethylmethacrylate (PMMA) and nacre powder to assess whether this bone-defect model would be suitable for further studies on bone repair. Cavities were successfully filled with nacre powder (21 cavities) or PMMA (8 cavities) while monitoring the process by interventional radiology. The experimental sheep vertebrae defect system is reproducible and appears to be a suitable model for testing injectable biomaterials for treating bone loss.

Stimulation of bone marrow cells and bone formation by nacre: in vivo and in vitro studies.

There is frequently a loss of vertebral bone due to disease or aging. Nacre (mother of pearl from the oyster Pinctada maxima) stimulates bone cell differentiation and bone formation in vitro and in vivo. Experimental bone defects were prepared in the vertebrae of sheep and used to test the suitability of nacre as an injectable osteogenic biomaterial for treating vertebral bone loss. Twenty-one cavities were prepared in the first four upper lumbar vertebrae of 11 sheep and filled with nacre powder. The lumbar vertebrae were removed after 1 to 12 weeks, embedded undecalcified in methacrylate, and processed for histological studies. The nacre slowly dissolved and the experimental cavities contained a large active cell population. By 12 weeks, the experimental cavity was occupied by newly matured bone trabeculae in contact with or adjacent to the dissolving nacre. The functional new bone trabeculae were covered with osteoid lined with osteoblasts, indicating continuing bone formation. The in vitro study on rat bone marrow explants cultured with a water-soluble extract of the nacre organic matrix also resulted in the stimulation of osteogenic bone marrow cells with enhanced alkaline phosphatase activity. Thus, both the in vivo and in vitro findings suggest that nacre contains one or more signal molecules capable of activating osteogenic bone marrow cells.

Near immunity to rice tungro spherical virus achieved in rice by a replicase-mediated resistance strategy.

ABSTRACT Rice tungro disease is caused by rice tungro bacilliform virus (RTBV), which is responsible for the symptoms, and rice tungro spherical virus (RTSV), which assists transmission of both viruses by leafhoppers. Transgenic japonica rice plants (Oryza sativa) were produced containing the RTSV replicase (Rep) gene in the sense or antisense orientation. Over 70% of the plants contained one to five copies of the Rep gene, with integration occurring at a single locus in most cases. Plants producing antisense sequences exhibited significant but moderate resistance to RTSV (60%); accumulation of antisense RNA was substantial, indicating that the protection was not of the homology-dependent type. Plants expressing the full-length Rep gene, as well as a truncated Rep gene, in the (+)-sense orientation were 100% resistant to RTSV even when challenged with a high level of inoculum. Accumulation of viral RNA was low, leading us to conclude that RTSV Rep-mediated resistance is not protein-mediated but is of the cosuppression type. Resistance was effective against geographically distinct RTSV isolates. In addition, RTSV-resistant transgenic rice plants were unable to assist transmission of RTBV. Such transgenic plants could be used in an epidemiological approach to combat the spread of the tungro disease.

Expression and inheritance of multiple transgenes in rice plants.

The ability to control integration, inheritance, and expression of multiple transgenes is a prerequisite for manipulating biosynthetic pathways and complex agronomic characteristics in plants. One hundred and twenty-five independent transgenic rice plants were regenerated after cobombarding embryogenic tissues with a mixture of 14 different pUC-based plasmids. Eighty-five percent of the R0 plants contained more than two, and 17% more than nine, of the target genes. Plants containing multiple transgenes displayed normal morphologies and 63% set viable seed. Multigene cotransformation efficiency was correlated with the ratio in which the plasmids were mixed with respect to the selectable marker. All target genes had an equal chance of integration, indicating that the nature of the coding region had no effect on the efficiency of integration. Three plant lines containing 11, 10, and 9 transgenes, respectively, were analyzed for patterns of integration and inheritance until the R3 generation. Integration of multiple transgenes occurred at either one or two genetic loci, with inheritance conforming to a 3:1 Mendelian ratio. Coexpression of four marker genes was investigated until the R2 generation.

Mechanisms of severe, immediate reactions to iodinated contrast material.

PURPOSE: To measure and elucidate the mechanisms of presumed mediators of unexpected severe, immediate reactions to iodinated contrast materials. MATERIALS AND METHODS: In a multicenter study, 20 patients with mild to severe reactions to iodinated contrast material and 20 control subjects without reactions were evaluated. Ionic contrast material was associated with 18 (90%) of 20 reactions. Concentrations of plasma histamine, tryptase, urinary methylhistamine, specific immunoglobulin E (IgE) against ioxitalamate or ioxaglate, and the anaphylatoxins C3a and C4a were measured with radioimmunoassays; complement C3 and C4 levels were measured with nephelometry. RESULTS: Histamine levels were increased in 14 patients; tryptase levels, in 16; and methylhistamine levels, in six. Histamine and tryptase values correlated with the severity of the reaction (P < .02 and P < .004, respectively). Significantly higher levels of specific IgE against ioxaglate (P < .005) and ioxitalamate (P = .045) were found in patients. No differences were found for complement fractions. Skin test results in two patients with life-threatening reactions were positive for the administered contrast material. CONCLUSION: Histamine release and mast cell triggering are related to severe reactions. An IgE-related mechanism is strongly suspected. Radiologists should be trained to identify and treat anaphylactic shock in patients who react to iodinated contrast material.

Mutations in the HC-Pro gene of zucchini yellow mosaic potyvirus: effects on aphid transmission and binding to purified virions.

Transmission of zucchini yellow mosaic virus (ZYMV) by aphids was examined by introducing mutations within the highly conserved proline-threonine-lysine (PTK) motif of the helper component proteinase (HC-Pro) using a cDNA full-length clone. Replacement of proline by alanine (ATK) in the PTK motif abolished transmission almost completely both from plants and from membranes. Substitution of the basic lysine by glutamic acid (PTE) did not reduce the rate of transmission compared with the wild-type. Replacement of threonine by valine (PVK) or serine (PSK) resulted in a rate of transmission that was lower than that of the wild-type. The rate was lower for PSK than for PVK. Western blot comparison did not permit attribution of HC-Pro functionality in transmission to its level in the host. The HC-Pro of strains that effected transmission (with the wild-type PTK motif, and with the mutated PTE and PVK motifs) could also bind in vitro to virions of ZYMV. HC-Pro with a PSK motif, which was less effective in assisting transmission, could bind only weakly to virions, while HC-Pro of the almost non-transmissible strains (with PAK and ATK motifs) did not bind at all. Interestingly, positive binding was recorded for transmission-defective ZYMV-Ct, which has a PTK motif but has glutamic acid instead of lysine in the lysine-leucine-serine-cysteine (KLSC) motif. These findings support the 'bridge hypothesis', and confirm the binding of the HC-Pro to the virion. The possible role of the PTK and KLSC motifs in binding to the virus and to the mouthparts of the aphid is discussed.

Affinity purification of HC-Pro of potyviruses with Ni2+-NTA resin.

The HC-Pro of zucchini yellow mosiac virus (ZYMV) was found to bind to Ni2+-NTA resin with or without His-tagging. The binding stringency was similar to that observed in proteins with a zinc finger motif like the HC-Pro. Using this characteristic we developed an efficient and rapid method (2-3 h) for purification of the HC-Pro of several potyviruses. A dominant protein of about 150 kDa was extracted and identified as the HC-Pro of ZYMV by means of immunoblotting. About 150 microg of HC-Pro were partially purified from the soluble fraction of 1 g of leaves. High titers of HC-Pro protein were obtained from plants infected with four potyviruses [ZYMV, watermelon mosaic virus II (WMVII), papaya ringspot virus (PRSV) and turnip mosaic virus (TuMV)]. The HC-Pros of potato virus Y (PVY) and tobacco vein mottling virus (TVMV) did not bind to the Ni2+-NTA resin. The ZYMV-HC-Pro purified by the Ni2+-NTA resin could bind in vitro to ZYMV virions blotted onto a membrane. All the HC-Pros which had been successfully purified by the Ni2+-NTA resin were bound in vitro to membrane-blotted ZYMV coat protein. However, only the HC-Pros of ZYMV and WMVII were able to mediate aphid transmission of purified ZYMV virions. The purification procedure described herein is efficient and convenient, and enables HC-Pro for a number of potyviruses to be obtained in larger amounts and at higher purity than possible by means of most existing methods, based on ultracentrifugation.

Carotid artery stenosis: treatment with protected balloon angioplasty and stent placement.

PURPOSE: To assess effectiveness of endovascular treatment of carotid artery stenosis by means of angioplasty with cerebral protection and stent placement. MATERIALS AND METHODS: Angioplasty was performed for carotid artery stenosis in 259 patients. Cerebral protection (triple coaxial catheter) was used in 136 cases of atherosclerotic stenosis in the internal carotid artery or in the carotid bifurcation and was not used in 123 cases. A stent was placed in 69 patients when images obtained immediately after angioplasty showed signs of dissection or insufficient arterial opening. RESULTS: No procedure-related complications occurred in the 71 cases of nonatherosclerotic stenosis and in the 14 cases of proximal carotid artery and siphon atherosclerotic stenosis. Among the 38 patients who underwent angioplasty without cerebral protection, dissection occurred in two (5%) and embolic complication occurred in three (8%) during the procedure. Among 136 patients in whom cerebral protection was used, no embolic complications occurred during angioplasty, and two (1%) occurred during or after stent placement without protection. No residual flaps were found after stents were placed, and the restenosis rate decreased from 16% to 4%. CONCLUSION: Endovascular treatment can be considered for all types of carotid artery stenosis. Cerebral protection is mandatory to eliminate embolic complication in cases of atherosclerotic stenosis in the internal carotid artery or carotid bifurcation. Stent placement has eliminated the risk of immediate dissection and reduced the risk of delayed restenosis.

Genetic diversity of rRNA operons of unrelated Streptococcus agalactiae strains isolated from cerebrospinal fluid of neonates suffering from meningitis.

The genetic diversity of a collection of 54 unrelated Streptococcus agalactiae strains isolated from the cerebrospinal fluid of neonates and of 60 unrelated carrier strains was evaluated by investigating the restriction fragment length polymorphism of the rRNA gene region. Three restriction enzymes were selected for use: PstI, HindIII, and CfoI. Clustering analysis revealed two phylogenetic groups of strains with 40% divergence. Group I contained two clusters, A and B, and group II contained three clusters, C, D, and E. Strains of serotype Ia were mostly distributed in cluster A, and strains of serotype Ib were mostly distributed in cluster E. Serotype III isolates did not cluster. Nevertheless, 37 of 39 isolates belonging to cluster B were serotype III. With HindIII, two rRNA gene banding patterns characterized 38 of the 39 strains of cluster B, which represents a high-virulence group. In addition, two rRNA gene banding patterns with each enzyme and/or a pair of CfoI fragments of 905 and 990 bp identified 81% of the invasive strains. On account of the genetic homogeneity of the cerebrospinal fluid strains, ribotyping is a powerful typing method for investigation of nosocomial or epidemic invasive infections only when all three enzymes are used or when PstI and HindIII or PstI and CfoI are combined with serotyping (index of discrimination, > 0.95).

Radiological confirmation of brain death: digitised cerebral parenchymography. Preliminary report.

Rates of organ procurement from brain dead subjects have fallen substantially in recent years. In France, the legal definition of brain death is based on electroencephalographic criteria in patients with clinical evidence of irreversible coma. However, sedative drugs used in intensive care units usually render the electroencephalogram uninterpretable, and in our medicolegal framework, it is necessary that intracerebral circulatory arrest be demonstrated. We discuss the value of the various available techniques and report our experience with digitised intra-arterial cerebral parenchymography. This simple, fast technique does not alter physiological conditions and provides high-quality images, ensuring prompt diagnosis, which is a prerequisite for optimal organ harvesting.

Cervical automated discectomy. Report of 150 cases and evolution in the management of failure cases.

SUMMARY: The lumbar automated discectomy system described by Onik has been used in the treatment of cervical disk herniations whose symptomatology resisted medical treatment. Experience on 150 patients is reported showing a 74.5% success rate. This series performed in most cases on an outpatient basis had no complications. Up to 1992 failure cases were treated by intradiscal injections of triamcinolone with 62 % of success. This complementary technique was abandonned after the description of epidural calcifications secondary to this type of injections in the lumbar area. Since 1992, failure cases have been managed differently with injections of steroids in the cervical joints, especially when a hypertrophy of the ligamentum ftavum supposedly a sign of an inflammatory posterior component of the pain was demonstrated on the CT. Nine patients received intradiscal injections of microdoses (600IU) of chymopapaine with excellent results. No patient has had open surgery since 1992. It is concluded that percutaneous automated discectomy is a very promising and safe technique which can be used as a first choice technique for most cervical disk herniations resisting medical treatment.

Local intraarterial thrombolysis in the carotid territory.

SUMMARY: A new series of 142 patients treated by local intraarterial thrombolysis is presented. After haemorrhage was ruled out by CT, all patients had an emergency angiogram. Patients with occlusion of the lenticulostriate arteries were not treated after the sixth hour (79 cases). Patients without involvement of these arteries were treated up to the 12th hour (61 cases). This selection led to a dramatic reduction of post-thrombolysis intraparenchymatous haemorrhage (0.7%) compared to other series. All deaths (7 cases) were related to vasogenic oedema due to incomplete reduction of infarcted cerebral volume, in most cases (4 cases) in intracerebral extension of a cervical internal carotid occlusion. Digitized parenchymography proved to be a reliable technique to document the exact location and extent of brain ischaemia before and after thrombolysis. It also allows a prognosis of spontaneous recovery without using thrombolysis. By reducing the infarcted cerebral volume, local intraarterial thrombolysis seems beneficial to the patient as long as a strict selection based on the angiographic location of the occlusion and the time delay is respected.