Destruction of Leishmania mexicana amazonensis amastigotes within macrophages in culture by phenazine methosulfate and other electron carriers.

Exposure of macrophages infected with Leishmania mexicana amazonensis to phenazine methosulfate (PMS) resulted in rapid damage and disappearance of the intracellular amastigotes without obvious ill effects to the host cells. The reduction of the percent infection was related to the concentration of PMS and to the duration of the pulse. Most Leishmania disappeared within 2 h of a 2-h pulse with 10 muM of the drug. In contrast, pretreatment of the macrophages with PMS followed by removal of the drug before infection did not result in disappearance of the parasites. The pH of the PMS medium markedly influenced the disappearance of Leishmania: maximum effect was observed at pH 8.0, while the effect was negligible at pH 6.3. The pH effect may be related to pseudobase formation by the PMS cation. Dose-response curves for PMS were similar for resident, elicited, or activated macrophages. Observations by time-lapse cinemicrography documented the explosion-like fragmentation of the amastigotes within 1-2 h of exposure of infected macrophages to the drug. Parasite-derived granules and vacuoles were seen to scatter within the parasitophorous vacuoles. This early damage to the parasites was confirmed by transmission electron microscopic observations. Infected macrophages incubated with PMS displayed detectable vacuolar fluorescence, indicating that PMS or a metabolite of PMS had access to the vacuoles. A series of other electron carriers, including phenyl methanes, phenazines, oxazines, a xanthene, and a naphthoquinone, given continuously for 18 h, also induced the disappearance of the Leishmania. The most potent was crystal violet, active at 70 nM. The presence of apolar substituents enhanced activity and this is probably related to increased permeation of the dyes. Finally, PMS, as well as other electron carriers examined, also reduced the growth of Leishmania promastigotes in culture. The results are compatible with a direct effect of the drugs on the intracellular amastigotes, involving only a permissive participation of the macrophages. We propose that the diverse agents destroy the amastigotes by redox-cycling generation of active oxygen metabolites at or near the parasites. Alternatively, the effect of the drugs could be mediated by toxic free radical reduction species of the drugs or by interference with electron flow or with the intermediary metabolism of Leishmania.

Effect of selection on ancestry: an exactly soluble case and its phenomenological generalization.

We consider a family of models describing the evolution under selection of a population whose dynamics can be related to the propagation of noisy traveling waves. For one particular model that we shall call the exponential model, the properties of the traveling wave front can be calculated exactly, as well as the statistics of the genealogy of the population. One striking result is that, for this particular model, the genealogical trees have the same statistics as the trees of replicas in the Parisi mean-field theory of spin glasses. We also find that in the exponential model, the coalescence times along these trees grow like the logarithm of the population size. A phenomenological picture of the propagation of wave fronts that we introduced in a previous work, as well as our numerical data, suggest that these statistics remain valid for a larger class of models, while the coalescence times grow like the cube of the logarithm of the population size.

Phenomenological theory giving the full statistics of the position of fluctuating pulled fronts.

We propose a phenomenological description for the effect of a weak noise on the position of a front described by the Fisher-Kolmogorov-Petrovsky-Piscounov equation or any other traveling-wave equation in the same class. Our scenario is based on four hypotheses on the relevant mechanism for the diffusion of the front. Our parameter-free analytical predictions for the velocity of the front, its diffusion constant and higher cumulants of its position agree with numerical simulations.

Improving agglutination tests by working in microfluidic channels.

Latex agglutination tests are used for the diagnosis of diseases in man and animals. They are generally simple, cheap, and do not require sophisticated equipment, nor highly specialized skills. In this Technical Note, we put latex agglutination tests in a microfluidic format. The experiment is performed in PDMS (polydimethylsiloxane) microchannels, using streptavidin-coated superparamagnetic beads and a magnetic field. The target molecule is biotinylated protein A. By taking full advantage of the microfluidic conditions (scaling down of the detection volume and controlled action of the shear flow), we achieved an analytical sensitivity of 10 fmol l(-1)(several hundreds of fg ml(-1)) and a fast response (a few minutes) ; the test is also quantitative. Performances of agglutination tests can thus be improved by orders of magnitude by adapting them to a microfluidic format; this comes in addition to the usual advantages offered by this technology (integration, high throughput etc.).

Aggregation of paramagnetic particles in the presence of a hydrodynamic shear.

We present an experimental study of the aggregation of paramagnetic particles, in the presence of controlled laminar shear flow, conducted in microchannels subjected to an external magnetic field. The microfluidic channels are made of either glass/silicon or polydimethylsiloxane. In ranges of time up to hundreds of seconds, the growth mechanism of the linear chain consists of the accumulation of isolated particles or small clusters onto existing chains, which are all moving at different speeds. In this time regime the chain length increases linearly and has a growth rate that increases as a power law with the shear. At longer times the chain lengths saturate. The Smoluchovski model, which assumes single particle-chain interactions only, closely reproduces the observations both qualitatively and quantitatively. In particular, the evolution of the growth rate of the mean chain length with respect to the shear rate S, predicted as S1/4, is found to be consistent with the experiments.

Cloning of cDNAS that code for Plasmodium chabaudi antigens of the erythrocytic forms and cross-hybridize with P. falciparum.

Several Plasmodium chabaudi antigens are synthesized and the corresponding mRNAs are detected by cell-free translation only during specific stages of the erythrocytic cycle. Ring stage mRNA was used to construct a cDNA library in the plasmid vector pBR 322. The library was screened by differential hybridization with cDNA specific for ring stage parasites or schizonts. Two clones which showed some stage specificity and seven which did not were retained. Three clones were characterized by hybrid-selected translation. Clones 451, 148 and 443 contain sequences homologous to the messages for a 27 kDa stage-specific antigen, a 37 kDa early antigen and a 24 kDa antigen, respectively. The nine clones cross-hybridize to various degrees with cDNA from P. falciparum but cross hybridization intensities do not reflect the strength of immunological cross-reactivity.

In vivo time course of synthesis and processing of major schizont membrane polypeptides in Plasmodium falciparum.

A rapid method of separating membrane co-sedimentable and soluble components of Plasmodium infected erythrocytes is presented. We propose a nomenclature for major P. falciparum polypeptides, applicable to different isolates and based on their cellular location and stage specificity. For four of these polypeptides (185 kDa = Mp1; 120 kDa = Mp3; 76 kDa = Mp5; 90 kDa= Sp2) supposed to play a role in protective immunity, monospecific antibodies were available. We have studied their fate at the time of merozoïte release and reinvasion, and the possible correlations between these polypeptides, by pulse-chase experiments.

Investigating theory of mind in schizophrenia: influence of verbalization in disorganized and non-disorganized patients.

The ability to attribute intentions to others was studied in 13 disorganized and 13 non-disorganized schizophrenic patients, 13 depressed and 13 normal controls. Subjects were asked to complete 28 comic strips requiring theory of mind skills by choosing one out of three answer cards. The answer cards were simple pictures in a first condition and short sentences in a second condition. This study, which used the cognitive neuropsychological approach, underlies the existence of a link between disorganization patterns in schizophrenia and a deficit in the attribution of intentions to others, independently of the pictorial or verbal form of the mode of answering. In addition, results show that the non-disorganized schizophrenic group, depressed and normal controls perform similarly in both pictorial/verbal conditions. The influence of the absence/presence of verbal material on a task investigating theory of mind in schizophrenia is discussed.

Progressive-addition lenses in the management of esotropia with a high accommodation/convergence ratio.

In 25 children esotropia due to abnormal synkinesis between accommodation and accommodative convergence was corrected with progressive-addition lenses. Twelve of the children had been wearing conventional bifocals; the other 13 were given progressive lenses for the first time. The near esodeviation was satisfactorily neutralized in most cases, and nearly all the children had some stereopsis. All adapted well and without difficulty to the progressive lenses.

Preschool vision testing with a new device, the Scolatest.

To determine the reliability of results obtained in preschool children by school nurses with a new device for testing vision, the Scolatest, 153 children aged 4 to 5 years were presented with the Snellen E on the standard American Optical projector and with five letters of the Sheridan test (H, O, V, T and X) on the Scolatest. Another 212 children aged 3 to 4 years were presented with the Allen symbols on the projector and with the Pigassou symbols on the Scolatest. The tests with the projector were given at 6 m by an experienced pediatric orthoptist, those with the Scolatest at 2.5 m by a school nurse. The proportion of good responses was higher with the Pigassou symbols than with the Allen symbols. The results with the Sheridan letters and the Snellen E were similar up to 20/30; beyond 20/30 the Snellen E appeared unreliable. The four vision-testing systems were also presented by a school nurse at 2.5 m on the Scolatest to 102 children aged 4 to 5 years (Snellen E and the five Sheridan letters) and 80 children aged 3 to 4 years (Allen and Pigassou symbols). The proportions of good responses were more comparable. The results suggest that a working distance of 2.5 m should be used in testing vision in preschool children. Visual screening at this distance should test acuity beyond the 20/30 equivalence if results comparable to those at 20 feet with the 20/30 standard requirement are to be obtained.

Binding properties of the conjugates of oligo(2'-O-methylribonucleotides) with minor groove binders targeted to double stranded DNA.

Design, synthesis, physico-chemical and in vitro biological studies of new pyrimidine oligo(2'-O-methylribonucleotide) conjugates with oligocarboxamide minor groove binders (MGB) and benzoindoloquinoline intercalator (BIQ) are described. These conjugates formed stable triple helices with the target double-stranded DNA and inhibited its in vitro transcription upon binding.

[The contribution of "time-of-flight" MRI-angiography in the study of neurovascular interactions (hemifacial spasm and trigeminal neuralgia)]. / Apport de l'angio-IRM "temps de vol" dans l'exploration des conflits neurovasculaires (hémispasme facial et névralgie du trijumeau).

The purpose of this study was to investigate capabilities of Magnetic Resonance Angiography (MRA) in delineating neurovascular compression which has emerged as the most frequent etiology in cases of Hemi-Facial Spasm and Trigeminal Neuralgia. MR investigations were carried out at 1.5 t unit (Magnetom Vision, Siemens). The examination consisted of 3D time-of-flight MRA (3d TOF) protocol, with a FISP sequence (Fast Imaging Steady Precession) and magnetization transfer. Imaging parameters were; TR 39 ms, TE 7 ms; MX 256-512; FOV 210-210 mm. Time acquisition is 10 mm 30 s. The axially acquired angiographic slices were reformatted with a multiplanar reconstruction program (MPR) along and across the plane of facial and trigeminal nerves. Then millimetric raw data images were postprocessed with a maximum intensity projection (MIP) technique. 58 patients presented either with hemifacial spasm (36 cases, 16 women, 20 men, mean age: 58.5 y) or trigeminal neuralgia (22 cases, 13 women, 8 men, mean age: 51 y) were compared with 17 patients (9 women, 8 men, mean age: 57.5 y) as references. MRA with MIP and MPR techniques reliably demonstrates neurovascular compression at the root entry zone (REZ), and allows recognition of the implicated vascular loop in 34 the cases of hemifacial spasm investigated. Raw data were post-processed in an axially oblique plane parallel to the acoustico-facial bundle and secondarily reconstructed in coronally obliques views. These reconstructed images clearly delineate the cross-compression of the emerging facial nerve. The neurovascular conflict was related to an arterial loop from the postero-inferior cerebellar artery (PICA, 21 cases, 61%) and the antero-inferior cerebellar artery (AICA, 8 cases, 23%). Vertebral artery is implicated in conflicts in 5 cases. In 2 cases MRA exploration was negative. In HFS group distance between Vth nerve emergency and neuro vascular contact was measured and compared with control group; there is a significative difference (p < 0.01). In case of trigeminal neuralgia, MRA demonstrates neurovascular compression at the root entry zone of the Vth nerve of 16 patients. In theses cases, oblique and coronally reconstructed images are crucial in demonstrating neurovascular contacts. The vessel implicated in conflict is always the superior cerebellar artery (SCA). A supero-medial loop of the superior cerebellar artery was depicted in these 16 cases. Although 3 patients had negative MRA and MR studies, a case of compression of the origin of the Vth nerve by a enlarged draining vein in a case of brainstem arterio-venous malformation, a petrous apex meningioma was incidentally discovered and thoroughly investigated with gadolinium T1 weighted sequences and 1 demyelinating plaques located along the intraaxial course of the Vth nerve were noticed. In control group on 34 explanations only there are only 4 contacts between Vth nerve and SCA. MRA with a 3D-TOF FISP sequence allows recognition of neurovascular conflicts in case of hemifacial spasm and trigeminal neuralgia while MIP helps to characterize the implicated vessel. Sources images need to be carefully assessed in order to depict unsuspected pathology.

[Vertebro-epidural lumbosacral vascular malformations. An unusual cause of lumbo-sciatic pain]. / Les malformations vasculaires vertébro-épidurales lombo-sacrées. Une cause inhabituelle de lombo-sciatique.

Sciatica is most commonly caused by nerve root compression secondary to herniated disk. Rarely, it can be due to a lumbosacral vascular malformation. We present five cases with such a malformation, presenting as a chronic lumboradiculagia. The patients were explored with computed tomography, MRI and selective spinal angiography. Polymorphic anatomic and hemodynamic aspect of these cases are reported: 1. One vertebral hemangioma with epidural extension; 2. Three purely epidural malformations: a) one epidural cavernous hemangioma, b) one epidural arteriovenous malformation, c) one epidural varix; 3. One paravertebral arteriovenous fistula with epidural venous drainage. Diagnosis of these rare malformations may be difficult. A multiplanar cross-sectional magnetic resonance and computed tomography scan with contrast enhancement can show characteristic abnormalities and may assist in recognition these malformations. Selective spinal angiography confirms the diagnosis, allows to classify the malformation and is required to evaluate endovascular therapeutic possibilities.

[MRI of degenerative extrapyramidal syndromes. Parkinson disease, progressive supranuclear palsy and multiple system atrophy]. / L'IRM dans les syndromes extrapyramidaux d'origine dégénérative. La maladie de Parkinson, la paralysie supranucléaire progressive et l'atrophie systématisée multiple.

MR imaging of the brain, particularly with high field MR imagers, may demonstrate signal abnormalities consistent with deposits of iron or other paramagnetic substances in extrapyramidal disorders. The diagnosis of Parkinson's disease and progressive supranuclear palsy can be made on clinical grounds in most of the cases and MR signs are of little help in the diagnosis of these diseases. In patients with parkinsonian disorders poorly responding to therapy, MR imaging may be useful in demonstrating signal abnormalities in the putamen that may help to establish the diagnosis of striatonigral degeneration (component of multiple system atrophy) with a poorer prognosis than Parkinson's disease. Finally, MR imaging may be useful in the exclusion of other disease processes.

[The nasopharynx and deep spaces of the face: anatomy and applications to pathology]. / Rhinopharynx et espaces profonds de la face: anatomie et applications à la pathologie.

Deep facial spaces are anatomically delineated by the layers of deep cervical fascia. They are located between the skull base and the hyoid bone. Each space contains specific anatomic structures, which can be responsible for specific pathologic processes. Deep facial spaces can be divided in two medial odd spaces (pharyngeal mucosal and retropharyngeal spaces), and in three lateral even spaces (retrostylian, prestylian, and masticator spaces). The dividing of these core tissues are useful for the analysis of the lesions found in this area. CT scan and MRI (with axial and coronal views) provide precise analysis. The main lesions are: -medially, adenoidal hyperplasias and squamous cell carcinomas (pharyngeal mucosal space), adenopathies and abscess (retropharyngeal space). -laterally, salivary tumors (prestylian space), adenopathies, schwannomas and paragangliomas (retrostylian space). Masticator space (and especially pterygopalatine fossa) is an important way of communication and is often involved by the extension of locoregional pathologic processes.

[Intracranial dural arteriovenous fistula with perimedullary venous drainage]. / Fistules artério-veineuses durales intracrâniennes à drainage veineux périmédullaire.

Two cases of intracranial dural arterio-venous fistula (DAVF) with perimedullary venous drainage are reported. In both cases, MRI T2-weighted (T2W) images showed an hypersignal within the cervical cord with sparing of the thoracic cord. In one case perimedullary vessels were demonstrated on T1W images after gadolinium i.v. administration. A complete spinal angiogram did not show evidence of fistula but demonstrated the lack of opacification of the conus medullaris venous drainage. Cerebral angiogram demonstrated in the first case a foramen magnum DAVF and in the second case a petrous apex DAVF. Hypersignal limited to the cervical cord at MRI on T2W images remain exceptionnal in case of intracranial DAVF with perimedullary venous drainage. When neurological symptoms are suggestive, post gadolinium T1W sequences should be conducted, followed by selective spinal angiogram. If normal venous drainage is not objectivated (e.g. opacification of radiculo-medullary veins on the late phase), cerebral angiogram should be done to rule out an intracranial DAVF.

[Percutaneous vertebroplasty of the cervico-thoracic junction using an anterior route. Technique and results. Report of nine cases]. / Vertébroplastie percutanée de la charnière cervico-dorsale par voie antérieure. Technique et résultats. A propos de neuf cas.

Percutaneous vertebroplasty using fluoroscopy is a well known technique. Visualization of the posterior wall of the vertebra is mandatory. Good assessment of this part of the vertebra is usually difficult at the cervico-thoracic junction. We propose an original method to obtain adequate visualization of the posterior wall, avoiding the shoulders superposition. Using this technique, we performed twelve vertebroplasties in nine patients (one angioma and eleven metastatic lesions). Clinical outcome was good for all patients, even a total filling of the vertebra body by the cement was obtained in only eight cases on twelve. No clinical complication was observed.

Shaping Solid-State Supramolecular Cavities: Chemically Induced Accordionlike Movement of gamma-Zirconium Phosphate Containing Polyethylenoxide Pillars.

The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in gamma-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the gamma layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space.