Rectal lymphogranuloma venereum surveillance in France 2004-2005

Lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) caused by Chlamydia trachomatis strains belonging to the L1, L2 or L3 genotype. An alert about an outbreak of LGV among MSM in the Netherlands was published in January 2004. The first cases of rectal LGV in France were retrospectively diagnosed in March 2004 and sentinel surveillance for LGV was implemented in April 2004. Most of the participating centres were located in the cities of Paris and Bordeaux. Only confirmed rectal LGV cases were included in the surveillance. Rectal specimens from men that were found to be positive for C trachomatis by PCR were sent to the National Reference Centre for Chlamydia infection for genotyping. Simple epidemiological data provided by clinicians and genotyping results were sent to the Institut de Veille Sanitaire (InVS) where data were anonymously recorded. A total of 328 C. trachomatis rectal strains isolated in men were genotyped by the end of December 2005. Of these, 244 (74%) were LGV strains belonging to the L2 genotype. No L1 or L3 C. trachomatis genotype was found. Diagnosis was made retrospectively for 46 cases. The median age of patients with LGV was 39 years. HIV status was known for 96 patients: 82/96 (85%) were HIV-infected. Most LGV cases were diagnosed in the Paris area (92%). Among the remaining 26% C. trachomatis strains, genotypes Da and G were the most frequent. As with syphilis in recent years, the emergence of LGV in Europe is mainly affecting HIV-infected MSM. The screening and treatment of STIs should be included in the clinical follow-up of all HIV-infected MSM.

Rectal lymphogranuloma venereum surveillance in France 2004-2005

Lymphogranuloma venereum (LGV) is a sexually transmitted infection (STI) caused by Chlamydia trachomatis strains belonging to the L1, L2 or L3 genotype. An alert about an outbreak of LGV among MSM in the Netherlands was published in January 2004. The first cases of rectal LGV in France were retrospectively diagnosed in March 2004 and sentinel surveillance for LGV was implemented in April 2004. Most of the participating centres were located in the cities of Paris and Bordeaux. Only confirmed rectal LGV cases were included in the surveillance. Rectal specimens from men that were found to be positive for C trachomatis by PCR were sent to the National Reference Centre for Chlamydia infection for genotyping. Simple epidemiological data provided by clinicians and genotyping results were sent to the Institut de Veille Sanitaire (InVS) where data were anonymously recorded. A total of 328 C. trachomatis rectal strains isolated in men were genotyped by the end of December 2005. Of these, 244 (74%) were LGV strains belonging to the L2 genotype. No L1 or L3 C. trachomatis genotype was found. Diagnosis was made retrospectively for 46 cases. The median age of patients with LGV was 39 years. HIV status was known for 96 patients: 82/96 (85%) were HIV-infected. Most LGV cases were diagnosed in the Paris area (92%). Among the remaining 26% C. trachomatis strains, genotypes Da and G were the most frequent. As with syphilis in recent years, the emergence of LGV in Europe is mainly affecting HIV-infected MSM. The screening and treatment of STIs should be included in the clinical follow-up of all HIV-infected MSM.

Generalized head models for MEG/EEG: boundary element method beyond nested volumes

Accurate geometrical models of the head are necessary for solving the forward and inverse problems of magneto- and electro-encephalography (MEG/EEG). Boundary element methods (BEMs) require a geometrical model describing the interfaces between different tissue types. Classically, head models with a nested volume topology have been used. In this paper, we demonstrate how this constraint can be relaxed, allowing us to model more realistic head topologies. We describe the symmetric BEM for this new model. The symmetric BEM formulation uses both potentials and currents at the interfaces as unknowns and is in general more accurate than the alternative double-layer formulation.

Fast multipole acceleration of the MEG/EEG boundary element method

The accurate solution of the forward electrostatic problem is an essential first step before solving the inverse problem of magneto- and electroencephalography (MEG/EEG). The symmetric Galerkin boundary element method is accurate but cannot be used for very large problems because of its computational complexity and memory requirements. We describe a fast multipole-based acceleration for the symmetric boundary element method (BEM). It creates a hierarchical structure of the elements and approximates far interactions using spherical harmonics expansions. The accelerated method is shown to be as accurate as the direct method, yet for large problems it is both faster and more economical in terms of memory consumption.

A common formalism for the integral formulations of the forward EEG problem

The forward electroencephalography (EEG) problem involves finding a potential V from the Poisson equation inverted Delta x (sigma inverted Delta V) f, in which f represents electrical sources in the brain, and sigma the conductivity of the head tissues. In the piecewise constant conductivity head model, this can be accomplished by the boundary element method (BEM) using a suitable integral formulation. Most previous work uses the same integral formulation, corresponding to a double-layer potential. In this paper we present a conceptual framework based on a well-known theorem (Theorem 1) that characterizes harmonic functions defined on the complement of a bounded smooth surface. This theorem says that such harmonic functions are completely defined by their values and those of their normal derivatives on this surface. It allows us to cast the previous BEM approaches in a unified setting and to develop two new approaches corresponding to different ways of exploiting the same theorem. Specifically, we first present a dual approach which involves a single-layer potential. Then, we propose a symmetric formulation, which combines single- and double-layer potentials, and which is new to the field of EEG, although it has been applied to other problems in electromagnetism. The three methods have been evaluated numerically using a spherical geometry with known analytical solution, and the symmetric formulation achieves a significantly higher accuracy than the alternative methods. Additionally, we present results with realistically shaped meshes. Beside providing a better understanding of the foundations of BEM methods, our approach appears to lead also to more efficient algorithms.

Symmetric BEM formulation for the M/EEG forward problem

The forward M/EEG problem consists in simulating the electric potential and the magnetic field produced outside the head by currents in the brain related to neural activity. All previously proposed solutions using the Boundary Element Method (BEM) were based on a double-layer integral formulation. We have developed an alternative symmetric BEM formulation, achieving a significantly higher accuracy for sources close to tissue interfaces, namely in the cortex. Numerical experiments using a spherical semi-realistic multilayer head model with a known analytical solution are presented, showing that the new BEM performs better than the formulations used in our earlier comparisons, and in most cases outperforms the Finite Element Method (FEM) as far as accuracy is concerned, thus making the BEM a viable choice.

DNA gyrase and topoisomerase IV mutations in clinical isolates of Ureaplasma spp. and Mycoplasma hominis resistant to fluoroquinolones

Twelve clinical isolates of Ureaplasma spp. and one isolate of Mycoplasma hominis were examined for resistance to fluoroquinolones. Previously described mutations at positions 83 and 95 in GyrA (Escherichia coli numbering) and positions 80 and 87 in ParC were found. Unusual alterations were described at positions ParC 123 and 134.

Variational, geometric, and statistical methods for modeling brain anatomy and function

We survey the recent activities of the Odyssée Laboratory in the area of the application of mathematics to the design of models for studying brain anatomy and function. We start with the problem of reconstructing sources in MEG and EEG, and discuss the variational approach we have developed for solving these inverse problems. This motivates the need for geometric models of the head. We present a method for automatically and accurately extracting surface meshes of several tissues of the head from anatomical magnetic resonance (MR) images. Anatomical connectivity can be extracted from diffusion tensor magnetic resonance images but, in the current state of the technology, it must be preceded by a robust estimation and regularization stage. We discuss our work based on variational principles and show how the results can be used to track fibers in the white matter (WM) as geodesics in some Riemannian space. We then go to the statistical modeling of functional magnetic resonance imaging (fMRI) signals from the viewpoint of their decomposition in a pseudo-deterministic and stochastic part that we then use to perform clustering of voxels in a way that is inspired by the theory of support vector machines and in a way that is grounded in information theory. Multimodal image matching is discussed next in the framework of image statistics and partial differential equations (PDEs) with an eye on registering fMRI to the anatomy. The paper ends with a discussion of a new theory of random shapes that may prove useful in building anatomical and functional atlases.

Culture-negative endocarditis due to Chlamydia pneumoniae

We report on the case of a 54-year-old woman diagnosed as having culture-negative endocarditis (clinical and histopathologic evidence compatible with a recent episode of endocarditis). The responsibility of Chlamydia pneumoniae in this episode of endocarditis was suggested by a serological study and was then confirmed by the positive results of PCR and in situ hybridization tests with aortic and mitral valves tissues. To our knowledge, this is the first case of endocarditis due to C. pneumoniae confirmed by molecular biology-based techniques.

A normal rate of cellular cholesterol removal can be mediated by plasma from a patient with familial lecithin-cholesterol acyltransferase (LCAT) deficiency

Lecithin-cholesterol acyltransferase (LCAT) is the major enzyme involved in the esterification of cholesterol in circulating plasma lipoproteins. In the present study, we describe the molecular defects in the LCAT gene and in lipoprotein metabolism of a 34-year-old patient presenting with features of classic familial LCAT deficiency. DNA sequencing revealed two separate point mutations in exon 3 of the patient's LCAT gene: a C to A substitution converting Tyr(83) to a Stop and a C to T transition converting an Arg(99) to a Cys. Digestion of patient PCR-amplified DNA with the restriction enzymes AccI and AciI established that the patient was a compound heterozygote for both mutations. In vitro expression of LCAT (Arg(99)-->Cys) in human embryonic kidney-293 cells demonstrated reduced expression, as well as reduced secretion and/or increased intracellular degradation of the mutant enzyme with significantly decreased alpha-LCAT specific activity, thus, establishing the functional significance of the LCAT (Arg(99)-->Cys) mutation. The plasma cholesterol esterification rate (CER, 2+/-0.3 nmol/ml/h), alpha-LCAT activity (2.9+/-0.1 nmol/ml/h) and LCAT concentration (0.3+/-0.1 microg/ml) were 2.9%, 2.3% and 6.1% that of normal subjects, respectively. Analysis of the patient's plasma lipid profile revealed reduced plasma concentrations of total cholesterol (111+/-0.5 mg/dl), HDL cholesterol (1.6+/-0.2 mg/dl), apolipoprotein (apo) A-I (52+/-4 mg/dl) and apo A-II (11+/-0.5 mg/dl). Nevertheless, for the first time, we demonstrate that the LCAT-deficient plasma is as efficient as control plasma in cholesterol efflux experiments performed with [(3)H]-cholesterol loaded fibroblasts. This result could explain the absence of premature atherosclerosis in this LCAT-deficient patient.

Disseminated Mycobacterium lentiflavum infection in a human immunodeficiency virus-infected patient

We report the first case of Mycobacterium lentiflavum disseminated infection in a human immunodeficiency virus-infected patient. Conventional identification procedures failed to identify the mycobacterial strain, but sequencing of the 16S rRNA gene led to the species identification. Furthermore, we describe here the analysis of the 16S-23S rRNA internal transcribed spacer sequence of M. lentiflavum.

Bubbles interactions in the cahn-hilliard equation

We study the dynamics of bubbles in the one dimensional Cahn-Hilliard equation. For a gas of diluted bubbles we find ordinary differential equations describing their interaction which permits us to describe the ulterior dynamics of the system in very good agreement with numerical simulations.

[Implantation of iliosacral screws. Simulation of optimal placement by 3-dimensional X-ray computed tomography]

PURPOSE OF THE STUDY

Percutaneous iliosacral screws are used advantageously to fix unstable pelvic girdle avoiding the morbidity of open access for conventional screw fixation. The insertion technique must be precise due to the risk of injury to the lumbosacral nerve trunk, the cauda equina roots, and the first sacral nerve. We undertook a study of the implantation site of iliosacral screws looking for a means of standardizing the drilling procedure on the basis of 3D computed tomography (CT) data.

MATERIAL AND METHODS

A CT series with 3D reconstruction was performed on 11 pelvis bones. We retained pelvis parameters and characterized the axis and narrow zone of the sacral wing. The insertion routes of 6.5 mm cancelous bone screws were simulated: two iliosacral routes fixing S1, and two iliosacroiliac routes fixing S1 and S2. The values of the pelvic parameters and the positions of the screws were compared with the Spearman correlation test and graphic regression.

RESULTS

The pelvic incidence was a mean 47 degrees. The length of the sacral wing was a mean 73 mm. The narrow zone of the wing was 47 mm from the lateral iliac fossa. In the narrow zone, the wing section showed an oval shape: 22 mm largest diameter, 11 mm smallest diameter. The wing was oriented 84 degrees in the paracoronal plane perpendicular to the plane of the sacral plate, 67 degrees in the para-axial plane parallel to the sacral plate, and 37 degrees in the sagittal plane of the subject. The length of the upper S1 screw was a mean 80 mm. This upper screw was inclined 89 degrees in the para-coronal plant, 61 degrees in the para-axial plane and 28 degrees in the sagittal plane. The length of the lower S1 screw as a mean 80 mm. This lower screw was inclined 74 degrees in the para-coronal plane, 91 degrees in the para-axial plane and 110 degrees in the sagittal plane. The fixation screws could be inserted in 12 out of 22 cases. Correlations were found with height of the subject, length of the wing and the screw, and screw inclination. The inclination of the upper S1 screw in the para-coronal plane was correlated with the larger diameter of the sacral wing.

DISCUSSION

The pelvis parameters measured were comparable with data in the literature. The very small dimensions of the narrow zone dictate a very precise drilling for the narrow zone. This narrow zone determines the inclination of the screw insertion. In the sagittal plane the standard deviation was very large making it impossible to interpret the data. The route of the upper screw runs obliquely forward in the plane parallel to the sacral plate. The lower screw runs upwardly in the plane perpendicular to the sacral plate. It does not appear possible to insert fixation screws in a routine procedure. Preoperative assessment would be necessary before percutaneous insertion.

CONCLUSION

The 3D CT reconstructions of the sacral wing can be used to determine the precise optimal position of the two iliosacral screws. The principle orientations can be deducted from the plane of the sacral plate. Approximate indications can help reduce operative time and exposure to irradiation (patient and surgeon). Percutaneous iliosacroiliac screw fixation cannot be proposed for all patients.

Chaotic alternation of waves in ring lasers

We intend to give an analytic description of the mechanisms involved in the periodic and chaotic wave alternation frequently observed in ring lasers. A set of amplitude equations is derived from the Maxwell-Bloch equations. These equations are studied analytically and numerically.

[Markers of lipid peroxidation, inflammatory proteins and plasma tocopherols in homozygotic and heterozygotic sickle cell anemia]

Lipoperoxidation final products represented by the TBARS (substances reacting with the Thiobarbituric acid), inflammatory reaction proteins and sera tocopherol have been studied in homozygous forms as well as in heterozygous forms of sickle cell diseases. The significant increase of TBARS (P < 0.001) measured by spectrofluorimetry, the considerable decrease of the sera alpha gamma tocopherol, measured by HPLC (P < 0.005) in all sickle cell patients, especially in crisis homozygous form, reinforce our previous study (22, 23, 24). The absence of links between the TBARS and the tocopherols (fig. 1) suggests that other defence mechanisms occur without vitamin E. The collapse of haptoglobinemia in homozygous sickle cell patients associated with the fall of hemoglobinemia indicates a severe tissue and intravascular hemolysis as a consequence of LPO. Furthermore, the simultaneous decrease of cholesterolemia seems to indicate important lipoperoxide activity detected in sickle cell patients.

The place of electron spin resonance methods in the detection of oxidative stress in type 2 diabetes with poor glycemic control

OBJECTIVE

Chronic production of reactive oxygen species (ROS) and/or deficiency in the antioxidant defense system are observed in non-insulin-dependent diabetes mellitus (NIDDM) patients. As an adjunct to the usual indirect parameters for evaluating oxidative stress, we assessed the feasibility of oxyradicals detection in venous blood by electron spin resonance spectroscopy (ESR). Detection of the ascorbate pool was also performed using the validated ESR analysis of the ascorbyl free radial (AFR)-dimethyl sulfoxide (DMSO) complex.

METHODS AND RESULTS

Plasma lipoperoxidation was characterized by higher levels of total MDA (1.50 +/- 0.08 nmol/L), lower levels of GSH (0.54 +/- 0.02 mmol/L) and of vitamin A (2.13 +/- 0.52 mumol/L) in the NIDDM group than in the controls (0.75 +/- 0.05 nmol/L, 0.90 +/- 0.05 mmol/L, 3.52 +/- 1.04 mumol/L, respectively). Improvement of the ESR measurement of oxyradical adducts has been previously obtained by addition of a new sensitive nitrone (DEPMPO), which acts as a spin-trap. However, in our experiment the ESR signal-to-noise ratio was too low to detect significative oxyradicals adducts in total venous blood of NIDDM patients having a weak production of ROS. A significant difference (p < 0.002) was observed in DMSO/AFR index between controls (24.00 +/- 4.10 nmol/L) and NIDDM patients (7.28 +/- 2.36 nmol/L) suggesting ascorbate depletion related to the free radical production.

CONCLUSION

The DMSO/AFR index could be an interesting additional marker of oxidative stress during a chronic production of ROS.

Genotypic characterization of seven strains of Mycoplasma fermentans isolated from synovial fluids of patients with arthritis

We performed a genotypic characterization of seven strains of Mycoplasma fermentans which have been isolated from the synovial fluid of patients with rheumatoid arthritis (n = 2), spondyloarthropathy (n = 1), and unclassified arthritis (n = 4). We compared them to three reference strains (strains PG18 and K7 and incognitus strain) and to a clinical isolate from the urethra of a patient with nongonococcal urethritis. The characterization methods included electrophoresis of native DNA, arbitrarily primed PCR, and restriction fragment length polymorphism analysis following conventional and pulsed-field gel electrophoresis. Southern blot analysis with a probe internal to an insertion sequence was performed with the restriction products produced by the last two techniques. No extrachromosomal DNA sequences were detected. The M. fermentans strains identified by these methods did not present a unique profile, but they could be separated into two main categories: four articular isolates were genetically related to PG18 and the three other isolates, the urethral isolate, and the incognitus strain were related to K7. We also looked for the presence of the bacteriophage MAV1 (associated with the arthritogenic property of Mycoplasma arthritidis in rodents) in the M. fermentans strains. MAV1 DNA was not detected in either the clinical isolates or the reference strains of M. fermentans.