ABSTRACT
Laser is a promising technique used for biopolymer surface modification with micro and/or nano features. In this work, a 193 nm excimer laser was used for poly (ethylene terephthalate) (PET) surfaces chemical patterning. The ablation threshold of the PET film used in the experiments was 62 mJ/cm(2) measured before surface modification. Surface chemical patterning was performed by irradiating PET film in a vacuum chamber filled with ammonia at the flux of 10, 15, 20, 25 ml/min. Roughness of the surface characterized by profilometry showed that there were no significant observed change after modification comparing original film. But the hydrophilicity of the surface increased after patterning and a minimum water contact angle was obtained at the gas flux of 20 ml/min. FT-IR/ATR results showed the distinct amino absorption bands presented at 3352 cm(-1)and 1613 cm(-1) after modification and XPS binding energies of C(1s) at 285.5 eV and N(1s) at 399.0 eV verified the existence of C-N bond formation on the PET film surface. Tof-SIMS ions mapping used to identify the amine containing fragments corroborates that amino grafting mainly happened inside the laser irradiation area of the PET surface. A hypothesized radical reaction mechanism proposes that the collision between radicals in ammonia and on the PET surface caused by the incident laser provokes the grafting of amino groups.
Subject(s)
Ammonia/chemistry , Ammonia/radiation effects , Biocompatible Materials/chemistry , Biocompatible Materials/radiation effects , Polyethylene Terephthalates/chemistry , Polyethylene Terephthalates/radiation effects , Materials Testing , Membranes, Artificial , Surface PropertiesABSTRACT
OBJECTIVE: Renal transplantation improves many bone abnormalities inherent to chronic renal insufficiency, but also introduces new deleterious factors, especially those related to immunosuppressive drugs. We have studied the bone mineral content of 40 pediatric renal transplant recipients; moreover, we have analyzed its possible relationships with phosphorous-calcium metabolism, graft function and duration, steroid treatment and growth. PATIENTS AND METHODS: Bone mineral content was measured by dual energy X-ray absorptiometry (DEXA). The results were expressed as a z score in relation to age and sex. Immunosuppression was achieved by using triple therapy: azathioprine, cyclosporine A and prednisolone. At the time of the DEXA, 59% of the patients were on daily steroid treatment and 41% on alternate-day treatment. RESULTS: All patients presented bone mass losses with a maximal decrease between 5 and 21 months post-transplantation and a posterior tendency to recovery. Fifty percent of the children had severe osteopenia (bone mineral density < -1 SD). There was no statistically significant association between the severity of bone loss and values of ionized calcium, phosphorus, intact PTH, or calcitriol received. However, a linear correlation was found between cumulative steroid dose and osteopenia (r = -0.35, p < 0.05). Height and growth velocity were more affected in the severe osteopenia group. In this group, the proportion of children on daily steroid treatment was statistically higher (72% vs 45%, p < 0.05). CONCLUSIONS: Bone densitometry is an accurate, rapid and noninvasive method to measure renal transplant impact on the growing skeleton and it must be done in a periodic and standardized way.
Subject(s)
Bone Density , Kidney Transplantation , Adolescent , Anti-Inflammatory Agents/adverse effects , Body Constitution , Bone Diseases, Metabolic/chemically induced , Bone Diseases, Metabolic/diagnosis , Bone Resorption/chemically induced , Bone Resorption/diagnosis , Child , Densitometry , Dose-Response Relationship, Drug , Female , Graft Rejection/drug therapy , Humans , Kidney Failure, Chronic/surgery , Male , SteroidsABSTRACT
Asthmatic patients frequently develop wheezing after respiratory tract infection. Mycoplasma pneumoniae causes respiratory tract infections in children and in adults. The purpose of this study was to determine the frequency of recovery of M. pneumoniae from patients with asthma. Seventy-seven patients with asthma and 88 persons without asthma or any other respiratory tract disease (controls) were included in the study. Ages ranged from 8 months to 31 years. Throat swabs were taken and deposited in egg yolk broth with methylene blue in order to isolate M. pneumoniae. The bacterium was identified using inhibition of growth with homologous antiserum. The isolation rate in patients with asthma was 24.7% while that in controls was 5.7% (P < .01). The results suggest that M. pneumoniae colonizes a higher percentage of patients with asthma than controls and could possibly have induced the wheezing.
