Spectroscopic characterization of calcium phosphate precipitated under human eye conditions: An in vitro study

Calcification is a well-known process of calcium phosphate mineralization observed in intraocular lenses. Despite the many works conducted in this field, there is no strict explanation of the mechanisms of this process. In order to better understand the phenomenon, i.e., the mechanisms and structural conditions that promote calcification, any research observations should be conducted under conditions that best reflect those of the human eye. Taking into account the specific anatomy and physicochemical conditions of the human eye, the problem under discussion becomes difficult to solve in vitro. In the present study, calcium phosphates formed under conditions similar to those in the human eye were characterized using SEM/EDS and infrared spectroscopy. Conducted study showed the formation of white spherical precipitates, which are unstable when extracted from solution. Such precipitates were characteristic of solutions containing 1.5-3.0 mM² of solutes. Elemental analysis showed a Ca/P ratio of 1.64-1.65, which is similar to the ratio for hydroxyapatite (1.67). Chemical structure analysis revealed the presence of broad bending and stretching bands at 475-830 cm^-1 and 880-1250 cm^-1, respectively, which are characteristic of PO₄^3- groups in apatite calcium phosphates. In further analysis involving numerical fitting the bands corresponding to apatitic PO₄^3- and indicating the presence of calcium phosphates hydration were found. The results allow the selection of immersion media for further studies involving the incubation of hydrogel intraocular lenses.

Tellurite Glasses from the 70TeO2-5XO-10P2O5-10ZnO-5PbF2(X= Pb, Bi, Ti) System Doped Erbium Ions-The Influence of Erbium on the Structure and Physical Properties

In this article, we present research on the influence of erbium ions on the structure and magneto-optical properties of 70TeO₂-5XO-10P₂O₅-10ZnO-5PbF₂ (X = Pb, Bi, Ti) tellurite glass systems. Structural changes occurring in the glasses during doping with erbium ions were investigated using positron annihilation lifetime spectroscopy (PALS) and Raman spectroscopy. The X-ray diffraction (XRD) method was used to confirm the amorphous structure of the investigated samples. Based on the Faraday effect measurements and calculated values of Verdet constant, the magneto-optical properties of the glasses were determined.

Influence of W Addition on Phase Constitution, Microstructure and Magnetic Properties of the Nanocrystalline Pr9Fe65WxB26-x (Where: x = 2, 4, 6, 8) Alloy Ribbons

The aim of the present work was to investigate an influence of W addition on the phase constitution, microstructure and magnetic properties of the Pr₉Fe₆₅W_xB_26-x (where: x = 2, 4, 6, 8) alloy ribbons. Ribbons were obtained using the melt-spinning technique under low pressure of Ar. The as-cast samples were fully amorphous and revealed soft magnetic properties. These facts were confirmed by X-ray diffractometry, Mössbauer spectroscopy and magnetic measurements. Differential scanning calorimetry and differential thermal analysis allowed us to determine the thermal stability parameters of the amorphous phase. The Kissinger plots were constructed in order to calculate the activation energies for crystallization. Heat treatment carried out at various temperatures caused changes in the phase constitution and magnetic properties of the alloys. The phase analysis has shown the presence of the hard magnetic Pr₂Fe₁₄B and paramagnetic Pr_1+xFe₄B₄ phases. Additionally, for the x = 2 and x = 6 alloys, a crystallization of soft magnetic Fe₂B and α-Fe phases was observed. The Mössbauer spectroscopy allowed us to determine the volume fractions of constituent phases formed during annealing. The microstructure of annealed ribbons was observed using transmission electron microscopy.

A study of the effect of X-ray irradiation on the structure of Narafilcon A biopolymer soft contact lenses

BACKGROUND

The effects of external factors such as X-ray irradiation on the structure and physical properties of contact lenses are very important for both the patients using contact lenses and medical personnel.

OBJECTIVES

The aim of the study was to investigate the effect of X-rays on the structure of Narafilcon A silicone-hydrogel contact lenses.

MATERIAL AND METHODS

In order to study the structural changes caused by X-rays in Narafilcon A polymer contact lenses, the following spectroscopy methods were used: positron annihilation lifetime spectroscopy (PALS), Fourier transform middle infrared spectroscopy (FTIR) and Raman spectroscopy (RS). Irradiation of the investigated sample was carried out using an Elekta Synergy accelerator. The contact lenses were irradiated with the following total doses of X-rays: 0.05 Gy, 0.5 Gy, 0.8 Gy, and 1.0 Gy.

RESULTS

The PALS measurements showed that X-ray irradiation caused slight changes in the size of the free volume and the fractional free volume in the structure of the polymer contact lenses examined. However, the FTIR and RS measurements showed that X-rays did not break the monomer bonds in the polymeric structure of the sample.

CONCLUSIONS

The changes revealed by the PALS method may be related to possible displacement of monomer chains, resulting in changes in the dimensions and numbers of free volumes. The finding that X-ray radiation does not affect or damage polymer bonds can in the future contribute to the use of X-ray and gamma radiation to sterilize contact lenses.

Spectroscopic studies of the silicone oil impact on the ophthalmic hydrogel based materials conducted in time dependent mode

Silicone oil is the one of the artificial materials used in vitreoretinal surgery for retinal detachment treatment. Since the silicone oil is sometimes applied along with intraocular lens (IOL) implantation the direct influence of silicone oil on the artificial implant should be taken into account. Presented study was performed in order to determine the time-dependent impact of silicone oil on hydrogel based ophthalmic materials. Two kinds of IOLs based on hydroxyethyl 2-methacrylate (HEMA) hydrogel material were immersed in silicone oil based on linear poly(dimethylsiloxane) (PDMS). Incubation in oil medium was performed in 37°C for 1, 3 and 6months. After appropriate period of the incubation samples were examined by means of FTIR-ATR method as the technique of surface study as well as Positron Annihilation Lifetime Spectroscopy (PALS) as the method of internal structure investigation. Results obtained during the study revealed that silicone oil is not capable to penetrate the internal structure of investigated materials and its impact has come down to interaction with the samples surfaces only.

Measurements of Defect Structures by Positron Annihilation Lifetime Spectroscopy of the Tellurite Glass 70TeO2-5XO-10P2O5-10ZnO-5PbF2 (X = Mg, Bi2, Ti) Doped with Ions of the Rare Earth Element Er3

The objective of the study was the structural analysis of the 70TeO₂-5XO-10P₂O₅-10ZnO-5PbF₂ (X = Mg, Bi₂, Ti) tellurite glasses doped with ions of the rare-earth elements Er³⁺, based on the PALS (positron annihilation lifetime spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, the sizes of which range from a few angstroms to a few dozen nanometers. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ ₁ andτ ₂. Their interpretation was based on two-state positron trapping model where the physical parameters are the positron annihilation rate and positron trapping rate.

Nanoscale Observation of Dehydration Process in PHEMA Hydrogel Structure

One of the most important field of interest in respect to hydrogel materials is their capability to water storage. The problem mentioned above plays an important role regarding to diffusion of fluid media containing nanoparticles, what is very useful in biomedical applications, such as artificial polymeric implants, drug delivery systems or tissue engineering.In presented work, dehydration process in hydrogels used in ophthalmology as intraocular lenses was observed. Before measurements studied materials were immersed in deionized water and saline solution to obtain equilibrium swelling state. Studies of the dehydration process were carried out by use of gravimetric analysis, Fourier-Transform Infrared and Positron Annihilation Lifetime Spectroscopy. Obtained results revealed changes in hydrogen bonding structure and free volume holes induced by saline solution ingredients.

Optical and vibrational properties of phosphorylcholine-based contact lenses-Experimental and theoretical investigations

The Raman, MIR and UV-vis spectroscopy have been used to characterize Omafilcon A material constructing the one of the Proclear family contact lenses. The Omafilcon A is hydrogel material composed of 2-hydroxyethyl methacrylate (HEMA) and 2-methacryloyloxyethyl phosphorylcholine (PC) polymers crosslinked with ethyleneglycol dimethacrylate (EGDMA). Vibrational and electronic properties of the Omafilcon A material were also investigated by quantum chemical calculations. Experimentally obtained Raman, MIR and optical spectra were compared to the theoretical ones calculated applying RHF and DFT methodology. The quantum chemical calculations were performed for isolated monomers of lenses compounds as well as for their dimers and trimers to elucidate the effect of Omafilcon A polymerization and the role of an individual components.

An investigation of the effect of silicone oil on polymer intraocular lenses by means of PALS, FT-IR and Raman spectroscopies

The effect of the polydimethylsiloxane (PDMS) based silicone oil, that is widely used in vitreoretinal surgery, on internal structures of the polymer intraocular lenses was investigated. The effect of PDMS was studied on the polymethyl methacrylate (PMMA) rigid lenses and poly(2-hydroxyethyl methacrylate) (PHEMA) flexible lenses. The research was carried out by means of the positron lifetime spectroscopy (PALS) as well as the infrared spectroscopy (FT-IR) and the Raman spectroscopy (RS). The studies involving the use of PALS and FT-IR methods have revealed that the PHEMA based lenses absorbed, whereas the PMMA lenses did not absorb, silicone oil. The results obtained with the use of the RS method were inconclusive, probably due to the too low intensity of the characteristic PDMS bands. The evidence from this study was discussed in terms of physics and related to the clinical use of both silicone oil and intraocular lenses.

Investigation of the Degree of Disorder of the Structure of Polymer Soft Contact Lenses Using Positron Annihilation Lifetime Spectroscopy PALS

BACKGROUND

Hydrogel and silicone-hydrogel polymeric materials are widely used in ophthalmology for the manufacture of contact lenses. An important aspect is the investigation of the structure of these materials.

OBJECTIVES

This study has been conducted in order to compare the degree of disorder and presence of free volumes in the internal structure of the polymeric soft contact lenses Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). Differences in the occurrence of trapping centers for positrons and free volumes between the types of investigated contact lenses have been demonstrated.

MATERIAL AND METHODS

Two types of polymeric contact lenses were used as materials: Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). The study was performed using positron annihilation lifetime spectroscopy (PALS).

RESULTS

When the results of the measurements has been obtained, a graphical curve has created to describe the relationship of the number of annihilation acts in time. Significant changes were observed between the contact lenses investigated in positron trapping in macropores (based on a two-state model) and the presence of free volumes (based on the Tao-Eldrup model).

CONCLUSIONS

The use of the positron annihilation two-state model made it possible to demonstrate that a higher positron trapping rate in macropores occurs in the silicone-hydrogel contact lens. Additionally, calculations using the Tao-Eldrup model show the existence of free volumes in both types of materials. The size and fraction of free volumes is much larger in the silicone-hydrogel contact lens.

Comparison of Occurrence of Free Volumes for Rigid Gas Permeable and Soft Contact Lenses

BACKGROUND

The polymeric materials: hydrogel, silicone--hydrogel and methacrylic acid are used in ophthalmology for the manufacture of contact lenses. It is important to research the structure of these materials, mainly the prevalence of free volumes.

OBJECTIVES

The study has been conducted in order to comparison the presence of free volume gaps in the structure of the polymer soft contact lenses: Etafilcon A (hydrogel), Narafilcon A (silicone-hydrogel) and the polymer rigid gas permeable (RGP) contact lens (Fluor-Silicon-Methacrylat-Copolymer). In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses.

MATERIAL AND METHODS

Three types of polymer contact lenses were used as materials: Etafilcon A, Narafilcon A and Fluor-Silicon-Methacrylat-Copolymer. The study was done by means of positron annihilation lifetime spectroscopy (PALS).

RESULTS

As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses.

CONCLUSIONS

The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. There is a clear difference in the free volume sizes and their fractions between measured contact lenses are connected with oxygen permeability in these lenses. The results lead to the following connection: contact lenses of higher oxygen permeability coefficients and a water content of less, have more and larger free volumes than contact lenses of less oxygen permeability coefficient.

Influence of lanthanum on structural and magneto-optic properties of diamagnetic glasses of the TeO2–WO3–PbO system

This paper is focused on the design, fabrication and characterization of tellurite glass of composition TeO₂–WO₃–PbO in terms of La₂O₃addition.

Positronics of subnanometer atomistic imperfections in solids as a high-informative structure characterization tool

Methodological possibilities of positron annihilation lifetime (PAL) spectroscopy applied to characterize different types of nanomaterials treated within three-term fitting procedure are critically reconsidered. In contrast to conventional three-term analysis based on admixed positron- and positronium-trapping modes, the process of nanostructurization is considered as substitutional positron-positronium trapping within the same host matrix. Developed formalism allows estimate interfacial void volumes responsible for positron trapping and characteristic bulk positron lifetimes in nanoparticle-affected inhomogeneous media. This algorithm was well justified at the example of thermally induced nanostructurization occurring in 80GeSe2-20Ga2Se3 glass.

Studying functional properties of hydrogel and silicone-hydrogel contact lenses with PALS, MIR and Raman spectroscopy

Determination of free volume holes of the hydrogel and silicone-hydrogel polymer contact lenses were investigated. Two types of polymer contact lenses were used as materials: the first is a hydrogel contact lenses Proclear family (Omafilcon A), while the second is a silicone-hydrogel contact lens of the family Biofinity (Comfilcon A). Positron annihilation lifetime spectroscopy PALS was used to characterize geometrical sizes and fraction of the free volume holes in the investigated samples. There is a clear difference in the free volume sizes and their fractions between silicone-hydrogel and polymer hydrogel contact lenses which in turn are connected with oxygen permeability in these lenses. Apart from that, spectroscopic (middle infrared) MIR and Raman examinations were carried out in order to demonstrate the differences of the water content in the test contact lenses.

Study of free volumes of polymer hydrogel and -silicone-hydrogel contact lenses by means of the positron annihilation lifetime spectroscopy method

BACKGROUND

Polymer materials based on hydrogel and silicone-hydrogel materials are commonly used in ophthalmology. It is important to research the structure of these materials, mainly the prevalence of free volumes.

OBJECTIVES

The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer hydrogel and silicone-hydrogel contact lenses. In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses.

MATERIAL AND METHODS

Three different hydrogel and three different silicone-hydrogel polymer contact lenses were used as research material. The study was done by means of positron annihilation lifetime spectroscopy (PALS).

RESULTS

As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. The study revealed the existence of three τ1, τ2 and τ3 components. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses.

CONCLUSIONS

The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. The results lead to the following connection: contact lenses of higher oxygen permeability coefficient (silicone-hydrogel contact lenses) have more and larger free volumes than contact lenses of less oxygen permeability coefficient (hydrogel contact lenses).

Voids in mixed-cation silicate glasses: Studies by positron annihilation lifetime and Fourier transform infrared spectroscopies

PALS in comparison with FTIR studies have been applied to investigate the structure of different oxide glasses. Three components of the positron lifetime τ (τ1 para- and τ3 ortho-positronium and τ2 intermediate lifetime component) and their intensities were obtained. The results of the calculation of mean values of positron lifetimes for the investigated glasses showed the existence of a long-living component on the positron annihilation lifetime spectra. From the Tao-Eldrup formula we can estimate the size of free volume. On the basis of the measurements we can conclude that the size and fraction of free volume reaches the biggest value for the fused silica glass. The degree of network polymerisation increases void size.

Ageing phenomenon in acrylic polymer dental materials detected by means of positron annihilation lifetime spectroscopy

BACKGROUND

Polymer materials based on acrylic monomers are commonly used in dentistry. It is important to research the structure of dental filling materials towards the material ageing.

OBJECTIVES

The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer materials.

MATERIAL AND METHODS

Brand new, acrylic polymer based samples of dental Dipol materials were used as a research material. The study was conducted by means of the positron annihilation lifetime spectroscopy (PALS).

RESULTS

As a result of the conducted measurements, curves describing numbers of counts of the acts of annihilation in the time function were obtained. The conducted studies revealed the existence of four components τ1, τ2, τ3 and τ4. The τ3 and τ4 components are attributed to the pick-off annihilation of o-Ps orthopositronium trapping by free volume gaps and provide information about geometrical parameters of the volumes. LT 9 computer program was used to calculate components. Free volume holes were determined from empirical relationship between the radius of free volume and the long lifetime components.

CONCLUSIONS

Conducted studies indicate the presence of free volume holes in the research materials. It has been noted that a new long lifetime component is assigned to a new kind of free volumes that exist in the structure of material related to the material ageing.

Structural study of polymer hydrogel contact lenses by means of positron annihilation lifetime spectroscopy and UV-vis-NIR methods

A study has been conducted in order to determine presence of free volume gaps in the structure of structure of polymer hydrogel contact lenses made in phosphoryl choline technology and of the degree of defect of its structure. The study was made by means of positron annihilation lifetime spectroscopy. As a result of the conducted measurements, curves were obtained, which described numbers of counts of the acts of annihilation in the time function. The conducted studies revealed existence of three components τ(1), τ(2) and τ(3). The τ(3) component is attributed to the pick-off annihilation of o-Ps orthopositronium trapping by free volume gaps and provides information about geometrical parameters of the volumes. At the same time, the UV-vis-NIR spectrometry examination was conducted on the same samples in the spectral range 200-1,000 nm.

Structural studies of polymer hydrogel and silicone hydrogel contact lenses by means of positron lifetime spectroscopy methods

PURPOSE OF JOB: Currently, there isa need to increase comfort and visual acuity man. Simultaneously improving biocompatibility and minimizing the impact of the material on the physiology of the cornea is the primary driving force behind the evolution of materials used in the manufacture of contact lenses. Despite progressive development of modern materials science, there is still the problem of reducing the level of oxygen available to the cornea resulting in pathological changes in the cornea. Therefore, structural studies increases interesting in relating to the amorphous contact lenses polymeric materials.

MATERIALS AND METHODS

The aim of this work is structural investigation of polymer hydrogel and silicone hydrogel contact lenses made in the technology of PC (Phosphoryl Choline). The study method was used positron lifetime spectroscopy PALS.

RESULTS

As a result of the measurements obtained curve describing the dependence of the number of counts of acts of annihilation as a function of time.

CONCLUSIONS

The study of PALS showed the existence of three components. Component tau1 is responsible for the annihilation of free positrons and the annihilation of electrons vacancy-type point defects. Component tau2 is associated with defects in the volume of grain boundaries formed, dislocations or clusters of vacancies. The results of calculations of mean values positron lifetime samples, showed longtime component tau3 in the spectrum of positron lifetime. Component tau3 is assigned to pick-off annihilation of ortho-positronium o-Ps trapping by free volume and providing information on the geometric parameters of the volume.

Investigation of the free volume changes in one day hydrogel and one day silicone-hydrogel contact lenses by means of positron annihilation lifetime spectroscopy

PURPOSE OF JOB: The evolution of materials used to manufacture contact lenses, there is a need to increase comfort and visual acuity man while improving biocompatibility and minimizing the impact of the material on the physiology of the cornea. There is still a problem with limiting the level of oxygen available to the cornea, resulting in various diseases. Therefore, the aim of this work is to investigate the physical and structural properties of hydrogel and silicone-hydrogel contact lenses.

MATERIALS AND METHODS

To achieve the main objective, the project involves the complete, systematic and comprehensive research methodology, techniques of positron lifetime spectroscopy PAL associated with polymerization, nanovoid natural structure of modern polymeric materials used in ophthalmology. This method is particularly sensitive to detect the structure of disordered materials with structural defects. Therefore it is reasonable to use PAL spectroscopy in studies of polymer nanostructures change contact lenses used in ophthalmology.

RESULTS

As a result of the measurements obtained curve describing the dependence of the number of counts of acts of annihilation as a function of time. Distribution of positron lifetime spectra into three components, allows to extract the longest third component which gives information about the geometrical parameters of free volume. Clear changes were observed long-living component lifetimes of ortho-positronium and their intensities between the lenses tested.

CONCLUSIONS

The measurements allowed us to isolate and calculate the value of long-living tau3 and its intensity I3, which values are component of positron lifetime associated with the formation of ortho-positronium (o-Ps) and is a measure of the density distribution of free volume creation. The results of these measurements indicate that the formation of free volume holes takes place both in the hydrogel lens and silicone-hydrogel. However, the size of free volume and the amount of free volume occurring for silicone-hydrogel lenses are greater than for hydrogel lenses. The study nanovoid structure of polymeric materials, their size and number suggest a relationship with the oxygen permeability of contact lenses, which implies a continuation and extension of the initial research.

Investigation of free volume changes in the structure of the polymer bifocal contact lenses using positron lifetime spectroscopy PALS

Positron annihilation lifetime spectroscopy PALS has been applied of free volume properties in bifocal contact lenses. The measurements have been made on new lenses and then after one, two, three and four weeks wear. The longest lifetime, obtained via three-component analyses of the spectra, was associated with the pick-off annihilation of ortho-positronium trapped in the free volume. After wear of the lenses changes in the ortho-positronium lifetimes and the relative intensity of the longest component were observed. These results are discussed on the basis of a free volume model.

[Investigation of free volume changes in the structure of the polymer bifocal contact lenses by means of the positron annihilation method]

Positron annihilation lifetime spectroscopy has been applied of free volume properties in bifocal contact lenses. The measurements have been made on new lenses and then after one, and two weeks wearing by the patient. The longest lifetime, obtained via three-component analyses of the spectra, was associated with the pick-off annihilation of ortho-positronium trapped in the free volume. After one, and two weeks wearing of the lenses changes in the ortho-positronium lifetimes and the relative intensity of the longest component were observed. These results are discussed on the basis of a free volume model.

Efficacité et tolérance de la clarithromycine, forme à libération modifiée en traitement court de cinq jours dans les exacerbations aiguës de bronchite chronique, comparativement à la télithromycine

BACKGROUND

The extended-release formulation of clarithromycin (CLA-ER) allows using this macrolide as a single daily dose. The purpose of this study was to evaluate the efficacy and safety of the CLA-ER formulation (500 mgx2) vs telithromycin (TELI) (400 mgx2) as a short course 5-day treatment, once a day, in patients with AECB.

METHOD

This randomized double-blind study was conducted in patients with AECB without severe airflow limitation (FEV1>35%), with sputum purulence (mandatory criterion), and with either increased sputum volume or increased dyspnea, or both (Anthonisen criteria I or II).

RESULTS

Three hundred sixty-two patients were assessed (62.6 years of age+/-12.9, men: 58.8%) positive culture on inclusion for 53.8%, with Haemophilus influenzae (N=57), Moraxella catarrhalis (N=42), and Streptococcus pneumoniae (N=41). In the per protocol population, the clinical success rate at day 8 was 97% (161/166) vs 97% (146/151), 97.5% CI=[-4.12 -4.71], the clinical cure rate at day 30 was 78% (129/166) versus 77% (116/151), P=0.85, and mean time without recurrence was 62 days versus 61 days (P=0.51), in CLA-ER and TELI groups, respectively. Fourteen patients in the CLA-ER group (8.2%) and 20 patients in the TELI group (12.4%) experienced at least one treatment-related adverse event (P=0.21), upon which gastrointestinal events were the most commonly reported treatment-related ones.

CONCLUSION

CLA-ER (1000 mg once a day) for 5 days is at least as effective as telithromycin in the treatment of AECB without severe airflow limitation and is well tolerated.

Development and validation of a French obesity-specific quality of life questionnaire: Quality Of Life, Obesity and Dietetics (QOLOD) rating scale

OBJECTIVE

To develop and validate a new health related quality of life (HRQOL) questionnaire specific to obesity and its management.

METHODS

This study was in two parts. The first (Study 1) consisted of the creation of a new tool derived from the American "Impact of Weight on Quality of Life Questionnaire" (IWQOL, 74 items) by adding to it a 17 items specific complementary module. This initial questionnaire (91 items) was reduced so as to obtain a questionnaire adapted to socio-cultural factors of obesity and dietary weight management in France. The objective of the second (Study 2) was to validate this final questionnaire by evaluating its psychometric properties: construction validity, internal reliability, concurrent validity in relation to a generic questionnaire, the SF-12, clinical validity by studying the effects of age, gender and body mass index (BMI), and reproducibility.

RESULTS

The results of Study 1, obtained in 128 obese patients (mean age: 42.5 12.1, BMI: 34.5 2.8 kg/m2, women: 83.6%) enabled reduction of the 91 questionnaire items to 36, grouped into 5 dimensions: physical impact, psycho-social impact, sex life, comfort with food and diet experience. Two hundred and twelve patients (mean age: 43.3 12.2, BMI: 35.8 7.4 kg/m2, women: 77.7%) were included in Study 2, among whom 75 filled out the questionnaire twice at a one week interval. Analyses enabled verification of the construction validity and internal reliability (Cronbach alpha > 0.7) of the questionnaire as well as its concurrent validity in relation to summarized SF-12 scores and its clinical validity. The "physical impact" dimension was significantly influenced by BMI and age, the dimensions "sex life" and "diet experience" by the factors gender and BMI, while "psycho-social impact" was influenced by the 3 factors cited. Its reproducibility was also deemed satisfactory (intra-class correlation coefficient > 0.8).

CONCLUSION

This new questionnaire, called the "Echelle Qualité de Vie, Obésité et Diététique (EQVOD)"/"Quality of Life, Obesity and Dietetics (QOLOD)" rating scale is sufficiently reliable and reproducible to be used in clinical practice. It is a simple tool adapted to socio-cultural factors of obesity in France, enabling taking into account of the effects of dietary management on the HRQOL of obese people.

Genetic and phenotypic characterization of macrolide resistance in group A streptococci isolated from adults with pharyngo-tonsillitis in France

Three hundred and three strains of group A streptococci (GAS) isolated from adults with pharyngitis were tested to evaluate their phenotype of resistance to macrolides-lincosamides and to search for macrolide resistance genes. MICs of clarithromycin were determined. The overall rate of resistance to both erythromycin and clarithromycin was 9.6%. Constitutive, inducible and M phenotypes of resistance were detected in 4.3, 2 and 3.3% of strains, respectively. All constitutive phenotypes harboured ermB genes, whereas inducible phenotypes had the ermTR gene and M phenotypes had the mefA gene. In France, the current resistance rate of GAS to erythromycin and clarithromycin remains low.