Influence of the insertion of a cationic peptide on the size and shape of nanoliposomes: A light scattering investigation

Nanoliposomes are widely used for drug delivery in the human body. Cell-penetrating peptides are amphiphilic peptides inserting in the lipid bilayer of these lipid vesicles to induce the fusion with target cells. Separation by size exclusion chromatography coupled with the analysis by light scattering detectors provides both the hydrodynamic radius and the radius of gyration of all the liposomes in a sample. In this paper, the influence of the insertion of a cationic peptide, K₂LA₁₂, on the size and shape of anionic liposomes has been studied by this approach. The results obtained highlighted an increase in size and a slight deformation of the lipid vesicles depending on the concentration of peptides incorporated into the lipid bilayers.     

Vaccination against viral hepatitis B for public health personnel: the case of the National Fund of Social Security

Viral hepatitis B is endemic in Tunisia at an intermediate level. Health professional are a group particularly exposed to the infection. Immunization is the most efficient way to prevent this disease. In this study, we had try to estimate the cost of three strategies of immunization: immunization after a complete serology, immunization after a sequencial serology and immunization without previous serology. The study was conducted at the clinic of the National Fund of Social Security in El Khadra. All the personal of the clinic was invited to participate to a program of immunization after complete serology. Participation rate was at 93.8%. 33.3% of the personal was immunized (24% by a previous contact with the virus and 9.9% by a previous immunization). The costs of the three strategies were as below: immunization after complete serology: 53.4 tunisian dinars by person. immunization after sequantial serology: 33.06 tunisian dinars by person. immunization without serology: 16.2 tunisian dinars by person. Immunization without previous serology has the lower cost, and doesn't expose at any sid effect. However, a post immunization serology vaccinal should be desirable.     

Video head impulse test (vHIT) in migraine dizziness

Background and objective

Migraine is an extremely prevalent primary headache disorder that frequently associates parallel symptoms such as dizziness, tinnitus and hearing loss. Our aim is to investigate differences in video head impulse (vHIT) results with patients suffering from vestibular migraine (VM) and healthy people, taking into consideration mean values of vestibule ocular reflex (VOR) gain, occurrence of the compensatory saccades latency and amplitude. According to the results, determine the usefulness of vHIT in vestibular migraine diagnostics.

Le poly(α-acétoxystyrène) et les copolymères de l'α-acétoxystyrène avec le styrène et styrènes substitués obtenus par polymérisation thermique. Etude de la microstructure et de la stabilité thermique des polymères

The microstructure of poly(α-acetoxystyrene), prepared from α-acetoxystyrene by bulk thermal polymerization, was studied by ¹H and ¹³C NMR spectroscopy. Anomalies observed in the NMR spectra could be ascribed to fragmentations with formation of benzoxy and acetoxy radicals followed by re-initiation. The thermal degradation of the polymer, resulting in the formation of polyphenylacetylene, rules out certain types of transfer. α-Acetoxystyrene was copolymerized with styrene or substituted styrenes and the NMR study (¹H and ¹³C) was limited to α-acetoxystyrene. The composition of the copolymer could be ascertained by means of the resonances of the quaternary carbons of the aromatic cycle. The copolymers were characterized by viscometry, GPC, and thermal degradation. Their compositions, except that of poly(α-acetoxystyrene-co-styrene) were determined by elemental analysis.     

MR image segmentation of the knee bone using phase information

Magnetic resonance (MR) imaging is a widely available and well accepted non invasive imaging technique. Development of automatic and semi-automatic techniques to analyse MR images has been the focus of much research and numerous publications. However, most of this research only uses the magnitude of the acquired complex MR signal, discarding the phase information. In MR, the phase relates to the magnetic properties of tissues, information which is not found in the magnitude signal. As a result, phase is a complement to the magnitude signal and can improve the segmentation and analysis of MR images. In this paper, we consider the automatic classification of textured tissues in 3D MRI. Specifically, we include features extracted from the phase of the MR signal to improve texture discrimination in the bone segmentation. Our approach does not require phase unwrapping, with the MR signal processed in its complex form. The extra information extracted from the phase provides better segmentation, compared to only using magnitude features. The segmentation approach is integrated within a novel multiscale scheme, designed to improve the speed of pixel based classification algorithms, such as support vector machines. An order of magnitude increase is obtained, by reducing the number of pixels that need to be classified.     

Low‐power adiabatic sequences for in vivo localized two‐dimensional chemical shift correlated MR spectroscopy

Novel low‐power adiabatic sequences are demonstrated for in vivo localized two‐dimensional correlated MR spectroscopy, such as correlated spectroscopy and total correlated spectroscopy. The design is based on three new elements for in vivo two‐dimensional MRS: the use of gradient modulated constant adiabaticity GOIA‐W(16,4) pulses for (i) localization (correlated spectroscopy and total correlated spectroscopy) and (ii) mixing (total correlated spectroscopy), and (iii) the use of longitudinal mixing (z‐filter) for magnetization transfer during total correlated spectroscopy. GOIA‐W(16,4) provides accurate signal localization, and more importantly, lowers the SAR for both total correlated spectroscopy mixing and localization. Longitudinal mixing improves considerably (fivefolds) the efficiency of total correlated spectroscopy transfer. These are markedly different from previous 1D editing total correlated spectroscopy sequences using spatially nonselective pulses and transverse mixing. Fully adiabatic (adiabatic mixing with adiabatic localization) and semiadiabatic (adiabatic mixing with nonadiabatic localization) methods for two‐dimensional total correlated spectroscopy are compared. Results are presented for simulations, phantoms, and in vivo two‐dimensional spectra from healthy volunteers and patients with brain tumors obtained on 3T clinical platforms equipped with standard hardware. To the best of our knowledge, this is the first demonstration of in vivo adiabatic two‐dimensional total correlated spectroscopy and fully adiabatic two‐dimensional correlated spectroscopy. It is expected that these methodological developments will advance the in vivo applicability of multi(spectrally)dimensional MRS to reliably identify metabolic biomarkers. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Echo planar correlated spectroscopic imaging: Implementation and pilot evaluation in human calf in vivo

Exploiting the speed benefits of echo‐planar imaging (EPI), the echo‐planar spectroscopic imaging (EPSI) sequence facilitates recording of one spectral and two to three spatial dimensions faster than the conventional magnetic resonance spectroscopic imaging (MRSI). A novel four dimensional (4D) echo‐planar correlated spectroscopic imaging (EP‐COSI) was implemented on a whole body 3 T MRI scanner combining two spectral with two spatial encodings. Similar to EPSI, the EP‐COSI sequence used a bipolar spatial read‐out train facilitating simultaneous spatial and spectral encoding, and the conventional phase and spectral encodings for the other spatial and indirect spectral dimensions, respectively. Multiple 2D correlated spectroscopy (COSY) spectra were recorded over the spatially resolved volume of interest (VOI) localized by a train of three slice‐selective radiofrequency (RF) pulses (90°–180°–90°). After the initial optimization using phantom solutions, the EP‐COSI data were recorded from the lower leg of eight healthy volunteers including one endurance trained volunteer. Pilot results showed acceptable spatial and spectral quality achievable using the EP‐COSI sequence. There was a detectable separation of cross peaks arising from the skeletal muscle intramyocellular lipids (IMCLs) and extramyocellular lipids (EMCLs) saturated and unsaturated pools. Residual dipolar interaction between the N‐methylene and N‐methyl protons of creatine/phosphocreatine (Cr/PCr) was also observed in the tibialis anterior region. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.