Développement et validation des matériaux métalliques pour stents cardiovasculaires biodégradables par dépôt électrolytique

Les stents coronariens métalliques dégradables émergent comme une alternative possible aux stents permanents fabriqués à partir de métaux résistants à la corrosion comme l'acier inoxydable 316L. Le fer pur est un candidat intéressant pour les stents dégradables en termes de propriétés mécaniques, de dégradation et de biocompatibilité. Ce projet est le premier à étudier la faisabilité d’utiliser l'électroformage pour produire le fer comme matériau structural dans les stents dégradables. Dans ce projet, un processus de dépôt électrolytique a d’abord été développé. Les couches de fer produites ont une microstructure fine, une limite élastique élevée ainsi qu’une résistance à la traction ayant des valeurs comparables à celles de l'acier inoxydable 316L. Un traitement thermique de recuit à 550 ˚C pendant 1 h a produit une recristallisation dans le fer et a amélioré sa ductilité de 8 à 18 %. Des tests de corrosion par polarisation potentiodynamique et par immersion statique et dynamique ont permis l’étude de la dégradation du fer électroformé en solution de Hank. Il a été montré que le fer électrodéposé se corrode plus rapidement que le fer Armco ® déjà implanté comme stents biodégradables. L'effet de la densité de courant en tant que paramètre de l'électroformage sur la microstructure et la dégradation de fer a aussi été étudié. L’étude de diffraction d'électrons rétrodiffusés (EBSD) a montré que différentes microstructures, y compris la taille des grains et la texture, peuvent être produites à différentes densités de courant de 1 à 10 A dm-2. Le plus haut taux de dégradation a été obtenu pour le fer fabriqué à 5 A dm-2, car celui-ci possède la plus petite taille de grains et ceux-ci sont équiaxes avec des orientations aléatoires qui présentent un plus grand volume de joints de grains entraînant un taux de dégradation plus rapide. Enfin, le procédé d’électroformage a été appliqué avec succès pour la fabrication de mini-tubes de fer. Les mini-tubes de fer ont été électroformés sur les échantillons cylindriques d’étain qui ont été décollés par fusion du substrat après le processus. Les mini-tubes ont ensuite été utilisés pour la fabrication de stents de fer par découpe au laser. Les stents de fer ont montré une taille moyenne des grains de 5 µm après recuit et décapage à l'acide. Cette taille du grain est plus fine que celle généralement obtenue pour des stents SS 316L et pourrait fournir des propriétés mécaniques élevées et une dégradation ciblée pour les stents de fer électroformés.Degradable metallic coronary stents have emerged as possible alternatives for permanent stents fabricated from corrosion-resistant metals such as 316L stainless steel (316L SS). Pure iron has shown to be an interesting candidate for degradable stents in terms of mechanical properties, degradation and biocompatibility. This project is the first to investigate the feasibility of using electroforming process for production of iron for degradable stents where the material is used for a load-bearing application. In this project, firstly, an electroforming process was developed. The produced iron foils showed a fine microstructure and high yield and tensile strength were also obtained comparable to those of 316L SS. Annealing at 550˚C for 1h induced recrystallization in iron and improved its ductility from 8 to 18%. The investigation of the degradation of electroformed iron in Hank’s solution using potentiodynamic polarization, static immersion and dynamic degradation tests showed that it corrodes faster than Armco® iron previously investigated for degradable stents. The effect of current density as an electroforming parameter on the microstructure and thereby the degradation of iron was also studied. Electron backscatter diffraction (EBSD) showed that different microstructures including grain size and texture were produced at different current densities from 1-10 A dm-2. The highest degradation rate was obtained for iron fabricated at 5 A dm-2 since it possesses small grain size and equiaxed grains with random orientations providing more grain boundary volume can be held responsible for its faster degradation rate compared to the other iron samples. Finally, the electroforming process was successfully applied for the fabrication of iron tubes. Iron tubes were electroformed on Sn cylinders which were separated from them by melting after the process. The tubes were then used for the fabrication of iron stents by laser-cutting. Iron stents fabricated from electroformed tubes demonstrated an average grain size of 5 µm after annealing and acid-pickling. This grain size is finer than what usually obtained for 316L SS stents and could potentially provide high mechanical properties and targeted degradation for electroformed iron stents

Evaluating the Pupillary Distance in an Iranian Population and its Relation with age, Sex and Refractive Errors

Purpose: To find the mean value of pupillary distance and to evaluate the effect of age, sex and refractive errors on this distance in an Iranian population. Patients and Methods: In this study 703 individuals (403 women and 300 men) referred to the optometric department of Hazrat Khadijeh Clinic, Karaj, Iran, were selected. Subjects were divided into different age groups, pupillary distance was recorded after complete optometric examination, by a ruler while the patient was looking at target at a distance of 60 cm. Results: The mean age of participants was 31.07 ± 16.63 years. The mean pupillary distance was 59.2 ± 3.88 mm. Refractive errors had no statistically significant effect on pupillary distance and this distance was significantly greater in men than women (P < 0.001). The pupillary distance also increased with age. Conclusion: Similar to previous findings pupillary distance was affected by sex and age in an Iranian population. Refractive errors had no statistically significant effect on pupillary distance. Keywords: Pupil; Age; Sex; Refractive Errors; Ira

Influence of non starch polysaccharide-degrading enzymes on the meat yield and viscosity of jejunal digesta in broilers fed wheat/barley-based diet

This study was conducted to investigate the effect of four commercial multi-enzymes on the performance, meat yield, water intake, litter moisture and jejunal digesta viscosity of chicks fed wheat/barley based diet. A total of 195 1-d-old male broiler chicks (Ross 308) were allocated to 5 treatment groups, with 3 replicates per treatment group and 13 birds per replicate pen and all data were analyzed in a randomized complete block design. During the starter period, feed conversion ratio (FCR) was significantly (P < 0.05) decreased by only enzymes A, B and D. Moreover, FCR was significantly (P < 0.05) decreased by all enzymes in grower and entire periods. The relative weight of the breast as proportion of live weight was significantly (P < 0.05) decreased by only enzyme A. The relative weight of the abdominal fat as proportion of live weight was also significantly (P < 0.05) increased by enzyme D. Enzyme supplementation decreased viscosity of jejunal contents of chicks at day 28, but only enzymes A and D reduced significantly (P < 0.05) the viscosity of jejunum compared to control diet. In conclusion, there were similar improvements on FCR of birds fed diets with enzyme supplementation and choice preference of enzyme supplementation has to be base on its economic value

Investigating the Causes of Visual Impairment and Legal Blindness among Patients Coming to a Referral Hospital in Tehran, Iran

Purpose: To examine the causes of vision impairment and blindnessin a referral medical center in Tehran, Iran.Patients and Methods:  The present cross-sectional study was conducted on visually impaired and legally blind patients in optometricclinic of Rasoul-e-Akram hospital, Tehran, Iran, in 2015. We used the WHO criteria to evaluate visual impairment. The visual acuity of patients was recorded in a mono-eye fashion (right eye first then the left eye) using a 6-meter Snellen chart. The refractive error was evaluated and the best corrected visual acuity (BCVA) was recorded. Patients were then referred to ophthalmology department to diagnose the main cause of reduced vision.Results:  This study included 77 legally blind or visually impaired patients. After examining the underlying causes of visual impairment, we found that 41.17 % of visual impairment among patients was caused by cataracts and 29.41 % was caused by retinal diseases. Corneal pathology, glaucoma and other diseases were the rarer causes of low vision among subjects. The causes of legal blindness were different; retinal diseases were the main causes of legal blindness (46.51 %) followed by cataract (30.23 %) and corneal pathology (13.95 %).Conclusion:  Our results from a referral hospital in Tehran indicates that retinal pathology was the most common cause of legal blindness among our patients, while the most common cause of visual impairment was cataract. Due to the natural differences of epidemiologic findings gathered from a referral center and the community, multicenter studies are recommended to better evaluate the causes of visual impairment in our community.Keywords: Visual; Impairment; Legal; Blindness; Iran.

Severe Dry Eye in Covid-19 Patients Subject to Oxygen Therapy: A Case Report

Dry eye is a common problem that mainly affects affecting the adult population. In severe cases, it can lead to sterile corneal ulceration and perforation. We report a rare case of severe dry eye in a 50-year-old woman with COVID‑19 who that developed after using an oxygen therapy device . Despite the medical history of dry eye, the severity of the disease increased so that it did not respond to bandages contact lenses, antibiotics, and artificial tears without preservatives at two-hour intervals. However, autologous serum improved  but blurred vision and severe pain was improved by autologous serum. Awareness of possible ocular complications related to oxygen ventilation is important essential because prompt diagnosis and treatment can prevent severe visual consequences. In this clinical case, the timely management prevented a serious eye complication following oxygen therapy

Effect of Thermocycling and Type of Restorative Material on Microleakage of Class II Restorations

Objectives: Microleakage is a major cause of failure of dental restorations and results in development of secondary caries, tooth hypersensitivity and pulp pathosis. This study aimed to compare the microleakage of class II cavities filled with two types of composite resins and a compomer and subjected to thermocycling.Methods: In this in vitro experimental study, class II cavities with a gingival margin below the cementoenamel junction (CEJ) and beveled enamel margins were prepared in proximal surfaces of 60 molar teeth. The teeth were randomly divided into three groups of 20 and restored with Spectrum TPH3 and Esthet X composites and Dyract eXtra compomer. Each group was randomly divided into two subgroups (n=10) of control and thermocycling (1000 thermal cycles). Dye penetration in occlusal and cervical margins was scored under a stereomicroscope. Data were analyzed using the Kruskal Wallis test and Mann Whitney U test (P<0.05).Results: No significant difference was noted in microleakage of the three groups neither in the occlusal nor in the cervical margins in presence or absence of thermocycling (P>0.05). But, the microleakage in the cervical margins of compomer restorations was slightly higher than that of other groups especially after thermocycling.Conclusion: Microleakage of composite restorations was not significantly different from that of compomer restorations in the occlusal or gingival margins in presence or absence of thermocycling

Study of possible reduction or withdrawal of vitamin premix during finisher period in floor and battery cage broiler raising systems

The effect of dietary vitamin premix withdrawal or reduction between 29 and 35, 36 and 42, and 29 and 42 days of age on broiler chicken performance and immunocompetence was evaluated. The diets were formulated based on wheat and barley, and the experiment was conducted in floor pens (experiment 1) and battery cage (experiment 2) rearing systems in 7 treatments and 4 replicates for each treatment. The results of experiment 1 showed that vitamin premix reduction and withdrawal at 29 days of age did not impair performance during the final period of broiler chicken (29 to 42 days). The results of experiment 2 showed that there were no significant differences in performance with reduction or withdrawal of vitamin premix from diets in 29 to 35 days, but in 36 to 42 days of age, performance of birds fed with a diet that has no vitamin premix (T1) was significantly lower than other treatments (P < 0.05). The results of the two experiments demonstrated that immunocompetence response was not affected by treatments in the finisher period (P > 0.05). In conclusion, the results of this study indicated that in the battery cage system, it is possible to reduce dietary vitamin premix during finisher period, but withdrawal can negatively affect performance of broiler chickens, while in the floor system, it is possible to withdraw vitamin supplements in broilers’ finisher diets.Key words: Vitamin premix, reduction, broiler, wheat, immunocompetence

Serum Resistin Level in Obese Male Children

Objectives. Resistin is a member of cysteine-rich molecules. Several studies have been carried out to determine the biological effect of resistin, nevertheless a significant number are animal studies. All the studies performed regarding the relationship between serum resistin and obesity were merely accomplished in women. To the best of our knowledge, there is no survey on the correlation of the serum resistin level and obesity in male children. The aim of the present study is to assess serum concentration of resistin in obese male children. Methods. Between June 2009 and January 2010, we enrolled 42 randomly selected obese male students (body mass index (BMI) >95th percentile, age 15.7 ± 1.5). Thirty-eight healthy age-matched male students with normal BMI (<85th percentile) were selected as a control group for the purpose of comparison of the serum resistin levels. Results. Serum resistin levels were measured in obese and control group. No significant difference was found between resistin levels of the 2 groups (obese: 9.21 ± 5.6 ng/mL versus normal: 9.83 ± 4.3 ng/mL; P = .582). There was no significant correlation between serum resistin level and BMI. Assessing the resistin level in male subjects was the distinct feature of our study. The outstanding finding of this research is that there is no correlation between serum resistin level and obesity. Conclusion. We have demonstrated that there is no correlation between obesity in male children and resistin level. Consequently, metabolic abnormalities of insulin resistance seen in obese male patients are not related to resistin

Comparison of Different Levels of Vitamin Premix on Meat Lipid Oxidation in Floor and Battery Cage Broiler Raising Systems

A total of 1260 male broiler chicks (Ross 308) were allocated to 7 treatment groups (different levels and access time to vitamin premix (VP)) at 29 to 42 days of age, in floor system (Experiment 1) and battery cage system (Experiment 2). The oxidative stability was evaluated by thiobarbituric acid reactive substances (TBARS) on the thigh yield that were storage for 180 days in -20˚C. Results of experiment 1 showed that VP reduction and withdrawal from 29 d of age did not impair body weight, feed intake and feed conversion ratio during the final period of treatments (29-42d).Results of experiment 2 showed that there were no significant differences in the birds’ performance with reduction or withdrawal of VP from diets in 29-35 days among the experimental groups, but in 36-42 days of age, the performance of the group of birds fed with diet without VP (T1) was significantly lower than other groups. The results of experiment 2 showed that the performance of birds fed with diet without VP was significantly lower than other treatments in 36-42 days of age. The results of TBARS values in experiment 1 for thigh meat samples of birds slaughtered at 42 days of age showed that TBARS values of treatments without VP were significantly higher than other treatments. However in experiment 2, TBARS values of treatments without VP and with 33% VP were significantly higher than other treatments for birds slaughtered at 42 days of age. Finally, the results of this study demonstrate firstly that it is not possible to withdraw but it can be possible to reduce VP in finisher broiler's diets without negative effects on performance and meat quality during the time of freezing in both methods of rearing. Secondly, it is possible to reduce the VP levels in diet of broilers reared in floor system more than battery cage system