Disposable contact lenses and bacterial adhesion. In vitro comparison between ionic/high-water-content and non-ionic/low-water-content lenses

Biomaterials ◽  
1995 ◽  
Vol 16 (9) ◽  
pp. 685-690 ◽  
Author(s):  
Carla Renata Arciola ◽  
Maria Cristina Maltarello ◽  
Elisabetta Cenni ◽  
Arturo Pizzoferrato
Keyword(s):  
Water Content ◽  
Bacterial Adhesion ◽  
Contact Lenses ◽  
High Water ◽  
High Water Content ◽  
In Vitro Comparison

Analysis of deposits on high water content contact lenses

1983 ◽  
Vol 17 (2) ◽  
pp. 261-274 ◽  
Author(s):  
S. Hosaka ◽  
H. Ozawa ◽  
H. Tanzawa ◽  
H. Ishida ◽  
K. Yoshimura ◽  
...  
Keyword(s):  
Water Content ◽  
Contact Lenses ◽  
High Water ◽  
High Water Content

Preparation and characterization of modified chitosan for in vitro controlled release of vitamin B12

2013 ◽  
Vol 33 (8) ◽  
pp. 757-765 ◽  
Author(s):  
Ahmed Awadallah-F ◽  
Tahia B. Mostafa
Keyword(s):  
Water Content ◽  
Monomer Concentration ◽  
High Water ◽  
High Water Content ◽  
Vitamin B ◽  
Acryloyl Chloride ◽  
Modified Chitosan ◽  
Increase With Increase

Abstract Graft copolymerization of acrylonitrile and acryloyl chloride on to chitosan was prepared by γ-rays. Optimization of the grafting (%) was studied. The grafting (%) was observed to increase with increase in the irradiation dose and monomer concentration. The grafting percentages were about 52% and 36% from polyacrylonitrile and poly(acryloyl chloride), respectively. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to characterize the specimens. The modified chitosan was loaded with vitamin B12, demonstrated nearly 5.0±2.3% and 50.1±4.5% release in the media of pH 1.2 and 6.8, respectively, for amidoximated chitosan-grafted polyacrylonitrile and 3.6±1.1% and 36±2.4% in pH 1.2 and 6.8, respectively, for chitosan-grafted poly(acryloyl chloride), as determined by a traditional dissolution model. The modified chitosan specimens that uploaded with vitamin B12 displayed a more decremental release in the acidic medium than the neutral one. However, in order to incorporate in vivo gastrointestinal conditions, such as acidic pH and high water content in the stomach, low water content, and the presence of semi-solid mass in the large intestine, a new model, called flow through diffusion cell, was also used to study the drug release. The results of the two approaches produced different release profiles at the same pH values.

scholarly journals The influence of water content and ionicity on the efficacy of soft contact lens care regimens on Pseudomonas aeruginosa

2021 ◽  
Vol 80 (1) ◽  
Author(s):  
Rekha Hansraj ◽  
Siddeeqa Jhetam ◽  
Jared Haridutt ◽  
Tymon Lahner ◽  
Sthabile Madlala ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Water Content ◽  
Contact Lens ◽  
Contact Lenses ◽  
High Water ◽  
Health Science ◽  
High Water Content ◽  
Three Solutions ◽  
Soft Contact ◽  
Soft Contact Lenses

Background: Contact lens care regimens appear to be prescribed based on familiarity or by matching contact lens brands rather than consideration to efficacy.Aim: This study compared the effectiveness of multipurpose and peroxide cleaning solutions on low- and high-water content ionic and non-ionic soft contact lenses, in removing Pseudomonas aeruginosa (P. aeruginosa).Setting: The laboratory work was conducted by health science students in a graduate level programme in the microbiology laboratory at a university in south-eastern South Africa.Methods: A quantitative analytical experimental design was used. Four groups (labelled I, II, III and IV) of soft contact lenses, varied ionicity and water content were inoculated with P. aeruginosa and then exposed to three solutions containing antimicrobial ingredients, polyaminopropyl biguanide (Dymed), hydrogen peroxide (H2O2) and polyquaternium-1 (Polyquad). Each group contained 14 soft contact lenses, with the exception of Group III in which eight lenses were used. Saline served as the control. After 18 h, the remaining colony-forming units were counted using visual inspection as an indicator of efficacy against P. aeruginosa.Results: The solution containing H2O2 was found to be the most effective in removing P. aeruginosa from all Food and Drug Administration (FDA) groups of contact lenses whilst Dymed was found to be comparatively ineffective for this organism. Water content and ionicity had no effect on the efficacy of the solutions.Conclusion: Practitioners should consider the efficacy of the active ingredients against microorganisms when dispensing contact lens solutions, particularly for contact lens wearers at risk for P. aeruginosa infections.

scholarly journals Viability and germination of Scots pine seeds after freezing of harvested cones in vitro

2016 ◽  
Vol 46 (8) ◽  
pp. 1035-1041
Author(s):  
Markku Nygren ◽  
Katri Himanen ◽  
Hanna Ruhanen
Keyword(s):  
Water Content ◽  
Scots Pine ◽  
Seed Viability ◽  
High Water ◽  
Logistic Function ◽  
High Water Content ◽  
Maturation Stage ◽  
Freezing Treatment ◽  
Water Contents

Scots pine (Pinus silvestris L.) cone and seed water contents were analyzed in two consecutive seasons during maturation stage in the autumn and in January and March before seed dispersal. Cones with different water contents were subjected to 2 h of freezing at −30 °C, and seed viability and laboratory germination of seeds from individual cones after treatment were analyzed. Seed water content could be well predicted with the measurement of the cone water content, and the general relationship between these two could be described with a generalized logistic function. On average, the water content of cones was 5%–10% units higher than the seeds inside them. The higher the cone water content at the onset of freezing treatment, the higher the proportion of seeds with apparent damage (based on visual inspection of seeds using X-ray images) in that particular cone. High water content in cones also resulted in decreased germination after freezing treatment. The critical cone water content for 50% germination after freezing at −30 °C was approximately 31.3% (fresh mass basis). This corresponds to 21.6% water content in seeds.

Are High-Water-Content Contact Lenses Safe?

2006 ◽  
Vol 38 (1) ◽  
pp. 39-42
Author(s):  
R. P. Bhatia ◽  
Kshama Panday ◽  
Rashmi Srivastava ◽  
Hitendra Singh Indolia
Keyword(s):  
Water Content ◽  
Contact Lenses ◽  
High Water ◽  
High Water Content

Evaluation of an Immunoisolation Membrane Formed by Incorporating a Polyvinyl Alcohol Hydrogel within a Microporous Filter Support

1997 ◽  
Vol 6 (6) ◽  
pp. 585-595 ◽  
Author(s):  
Andrew R. Baker ◽  
Ronald L. Fournier ◽  
Jeffrey G. Sarver ◽  
Jennifer L. Long ◽  
Peter J. Goldblatt ◽  
...  
Keyword(s):  
Polyvinyl Alcohol ◽  
Water Content ◽  
Structural Integrity ◽  
High Water ◽  
Membrane Properties ◽  
High Water Content ◽  
Hybrid Hydrogel ◽  
Wide Range ◽  
Pva Hydrogel

An immunoisolation membrane formed by incorporating a high water content polyvinyl alcohol (PVA) hydrogel into a microporous polyether sulfone (PES) filter has been investigated in this study. The PVA hydrogel is formed in situ within the filter pores via glutaraldehyde (GA) crosslinking under acidic conditions. The tortuous nature of the microporous filter pores securely anchors the embedded hydrogel to provide excellent structural integrity. The high void fraction of the PES filter support (>80%) and high water content of the PVA hydrogel (>85% water by weight) allow excellent solute transport rates, while an appropriate level of glutaraldehyde crosslinking supplies the required molecular size selectivity. In vitro permeability measurements made with solutes covering a wide range of molecular sizes demonstrate high transport rates for small nutrient molecules with rapidly diminishing permeabilities above a molecular weight of approximately 1,000 Dalton. Implantation experiments show that the membrane properties are not deleteriously affected by prolonged in vivo exposure or common sterilization techniques. Thus, this hybrid hydrogel/filter membrane system offers a promising approach to the immunoisolation of implanted cells.

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