Polymeric Microfiltration Membranes Modification by Supercritical Solvent Impregnation-Potential Application in Open Surgical Wound Ventilation.

This study investigated supercritical solvent impregnation of polyamide microfiltration membranes with carvacrol and the potential application of the modified membranes in ventilation of open surgical wounds. The impregnation process was conducted in batch mode at a temperature of 40 °C under pressures of 10, 15, and 20 MPa for contact times from 1 to 6 h. FTIR was applied to confirm the presence of carvacrol on the membrane surface. In the next step, the impact of the modification on the membrane structure was studied using scanning electron and ion beam microscopy and cross-filtration tests. Further, the release of carvacrol in carbon dioxide was determined, and finally, an open thoracic cavity model was applied to evaluate the efficiency of carvacrol-loaded membranes in contamination prevention. Carvacrol loadings of up to 43 wt.% were obtained under the selected operating conditions. The swelling effect was detectable. However, its impact on membrane functionality was minor. An average of 18.3 µg of carvacrol was released from membranes per liter of carbon dioxide for the flow of interest. Membranes with 30-34 wt.% carvacrol were efficient in the open thoracic cavity model applied, reducing the contamination levels by 27% compared to insufflation with standard membranes.

Combinational Biomimicking of Lotus Leaf, Mussel, and Sandcastle Worm for Robust Superhydrophobic Surfaces with Biomedical Multifunctionality: Antithrombotic, Antibiofouling, and Tissue Closure Capabilities.

Surface wetting occurring in daily life causes undesired contaminations, which are critical issues in various fields. To solve these problems, the nonwetting property of a superhydrophobic (SH) surface has proven its utility by preventing contaminant infiltration, serious infections, or malfunction. However, the application of SH surfaces in the biomedical field has been limited due to the weak durability and toxicity of the related components. To overcome these limitations, we developed a robust and biocompatible SH surface through combinational biomimicking of three natural organisms, lotus leaf, mussel, and sandcastle worm, for the first time. Using the water-immiscible and polycationic characteristics of mussel adhesive protein (iMglue), an SH iMglue-SiO2(TiO2/SiO2)2 coating was fabricated by solution-based electrical charge-controlled layer-by-layer growth of nanoparticles (NPs). The fabricated iMglue-SiO2(TiO2/SiO2)2 SH surface showed excellent durable nonwetting properties and was applied to an intracatheter tube coating to develop antithrombotic catheters under blood flow. Furthermore, we developed a iMglue-employed SH patch for a tissue closure bandage by spraying hydrophobic SiO2 NPs on the iMglue-covered cotton pads. The prepared iMglue-employing SH patch showed perfect bifunctionality with excellent antibiofouling and tissue closure capabilities. Our work presents a novel, useful strategy for fabricating a biomedically multifunctional, robust SH surface through combinational mimicking of natural organisms.

Biocidal Efficacy of a Hydrogen Peroxide Lens Care Solution Incorporating a Novel Wetting Agent.

PURPOSE: To compare the antimicrobial effects of CLEAR CARE, a 3% hydrogen peroxide (H2O2) solution formulated for simultaneous cleaning, daily protein removal, disinfection, and storage of soft (hydrophilic) hydrogel, silicone hydrogel, and gas-permeable contact lenses, and CLEAR CARE PLUS, consisting of the 3% H2O2 solution plus a novel wetting agent, polyoxyethylene-polyoxybutylene (EOBO-21). METHODS: Three lots each of the 2 solutions were incubated with 5 compendial microorganisms required by the Food and Drug Administration (FDA) 510(k) and International Organization for Standardization (ISO) 14729 stand-alone procedures, 4 clinical isolates of Gram-positive and Gram-negative bacteria, and trophozoites and cysts of 2 Acanthamoeba strains that are associated with microbial keratitis. Microbial loads were evaluated after disinfection and neutralization. RESULTS: Both solutions exceeded the FDA/ISO stand-alone primary criteria against Gram-positive and Gram-negative compendial bacteria, yeast, and mold after only 1.5-hr disinfection/neutralization. At the recommended minimum disinfection time, bacteria were reduced by 4.4 to 5.1 logs, yeast by 4.4 to 4.9 logs, and mold by 2.9 to 3.5 logs with and without organic soil. In addition, both solutions eliminated or effectively reduced populations of clinically relevant ocular bacterial isolates (4.5-5.0 logs), Acanthamoeba trophozoites (3.4-4.2 logs), and cysts (1.5-2.1 logs). CONCLUSION: Both solutions eliminated or reduced populations of FDA/ISO compendial bacteria and fungi as well as clinically relevant microorganisms and Acanthamoeba trophozoites and cysts. The addition of EOBO-21 to the 3% H2O2 lens care solution had no impact on antimicrobial activity.

Vegetable moisturizing raw material from "Caatinga" Brazilian biome: safety and efficacy evaluations of O/W cosmetic emulsions containing Kalanchoe brasiliensis extract

The purpose of this study was to evaluate the safety of Kalanchoe brasiliensis extract, followed by the development of an oil in water emulsion containing the K. brasiliensis leaves extract and evaluating its clinical moisturizing efficacy. The formulations containing sodium acrylates/ Beheneth-25 methacrylate Crosspolymer (and) hydrogenated polydecene (and) lauryl glucoside and 0.5% of extract were prepared. The extract was considered as non-irritating through skin irritant tests. The stability testing was carried out in different conditions for 90 days. The skin hydration was measured by capacitance measurement and transepidermal water loss using biophysical techniques. The results indicate that the formulation containing 0.5% of extract increased the hydration of the stratum corneum up to 5 h after application on the forearm. The transepidermal water loss was reduced when compared to the untreated area and placebo area. Therefore, we can conclude that the increased skin hydration and protection of barrier function can be attributed to the K. brasiliensis extract. This research presents a new raw material from the Brazilian Caatinga biome and shows its possible application in the development of cosmetic products.

Hydrolyzed collagen interferes with in vitro photoprotective effectiveness of sunscreens

ABSTRACT The chronological skin aging is a progressive and natural process with genetic and physiological changes. However, ultraviolet (UV) radiation may accelerate the oxidative stress, generating carcinogenesis and photoaging. Natural compounds and their applications are considered a trend in the cosmetic market. The protein-based film-forming compounds play an important role, once it collaborates for the better distribution of sunscreens on the skin. Here we investigated the in vitro photoprotective effectiveness of sunscreens containing the hydrolyzed collagen associated with UVA, UVB and/or inorganic filters. Sunscreens were developed with octocrylene (7.5%), butyl methoxydibenzoylmethane (avobenzone) (3.0%) and/or titanium dioxide (5.0%), associated or not with the hydrolyzed collagen (3.0%). In vitro photoprotective effectiveness was determined in a Labsphere(r) UV2000S by the establishment of the sun protection factor (SPF) and critical wavelength (nm) values. Physicochemical and organoleptic characteristics were also assayed. The hydrolyzed collagen subjectively improved the formulation sensory characteristics. However, this bioactive compound led to a decrease of the SPF values of the photoprotective formulations containing octocrylene alone and octocrylene + butyl methoxydibenzoylmethane + TiO2. This inadequate interaction may be considered during the development of new sunscreens intended to contain protein-based components.

Use of Opuntia ficus-indica (L. ) Mill extracts from Brazilian Caatinga as an alternative of natural moisturizer in cosmetic formulations

ABSTRACT The aim of this work was the obtainment of Opuntia fícus-indica (L.) Mill extract for the development of cosmetic formulations and in vivo evaluation of its moisturizing effects. The formulations were tested for preliminary and accelerated stability. Organoleptic characteristics, pH values and rheological behavior were assessed. The evaluation of moisturizing efficacy of the emulsions formulated with 3.0% of Polyacrylamide (and) C13-14 Isoparaffin (and) Laureth-7 containing 1.0 and 3.0% of O. ficus-indica hydroglycolic extract (EHG001) was performed using the capacitance method (Corneometer(r)) and the transepidermal water loss - TEWL evaluation (Tewameter(r)). The emulsions formulated were stable, exhibiting pseudoplastic and thixotropic behavior. The results of evaluation of moisturizing efficacy showed increased skin hydration after five hours by mainly increasing the skin barrier effect. The formulations containing 1.0 and 3.0% of EHG001 enhanced the skin barrier effect by reducing TEWL up to four hours after application. The results observed suggest that O. ficus-indica hydroglycolic extract may act through a humectant and occlusion mechanism.

Sodium hypochlorite with reduced surface tension does not improve in situ pulp tissue dissolution.

INTRODUCTION: Sodium hypochlorite (NaOCl) solutions with added wetting agents are advertised to dissolve necrotic tissue in root canals faster than their counterparts without a lowered surface tension. This was tested in the current study, and the null hypothesis formulated was that there was no difference between a commercially available NaOCl solution with a lowered surface tension (Chlor-XTRA; Vista Dental Products, Racine, WI) and a counterpart containing the same amount of available chlorine without added wetting agents regarding the soft tissue that remains in oval-shaped canals after mechanical preparation and irrigation. METHODS: Formerly vital extracted teeth (N = 44, 22 pairs) with similar anatomy were radiographically paired and chemomechanically prepared. In 1 tooth from each pair, a 5.25% NaOCl solution with reduced surface tension was used; in the other, a pure, technical-grade NaOCl solution of 5.25% was used. The percentage of remaining pulp tissue (PRPT) was histologically assessed in root cross-sections. The non-Gaussian raw data were subjected to Kruskal-Wallis and Mann-Whitney U tests to verify the respective effect of the cross-section level and solution on the PRPT. The relationship between the cross-section level and the PRPT was estimated by the Spearman correlation test. The alpha-type error was set at 5%. RESULTS: The cross-section level significantly influenced the PRPT (P < .05), whereas the PRPT was not influenced by the solution used (P > .05). A significant inverse correlation was found between the cross-section level and the PRPT (P < .05, r = -0.330). The lower the distance to the apex, the higher the PRPT regardless of the solution used. CONCLUSIONS: Contrary to the advertised statement, the dental solution with a reduced surface tension did not dissolve vital pulp tissue in oval root canals any better than a conventional NaOCl solution of similar strength. Closer to the apex, pulp tissue dissolution is less efficient irrespective of the solution.

Photocrosslinkable hyaluronic acid as an internal wetting agent in model conventional and silicone hydrogel contact lenses.

Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal wetting agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy-attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications.

In vitro analysis of the physical properties of contact lens blister pack solutions.

PURPOSE: Since the initial development of silicone hydrogels, many modifications to the bulk and surface properties of the lenses have been undertaken to improve the wettability and comfort of the lenses. Recently, manufacturers have incorporated various "wetting agents" or surface-active agents into the blister packaging solutions (BPSs) of the lenses to improve initial comfort of the lens on eye. The purpose of this study was to measure and compare the pH, surface tension (ST), viscosity, and osmolality of BPSs for a variety of silicone hydrogel and polyHEMA-based hydrogel lenses. In addition, two saline solutions were tested for comparison purposes. METHODS: The pH, osmolality, ST, and viscosity were measured for the BPSs for lotrafilcon B and lotrafilcon A and lotrafilcon B with a "modified BPS" (m-lotrafilcon A, m-lotrafilcon B) (CIBA Vision, Duluth, GA); balafilcon A (Bausch & Lomb, Rochester, NY); galyfilcon A, senofilcon A, and narafilcon A (Johnson & Johnson, Jacksonville, FL); and comfilcon A and enfilcon A (CooperVision, Pleasanton, CA) and BPSs from two conventional polyHEMA-based materials-etafilcon A (Johnson & Johnson) and omafilcon A (CooperVision). The two saline solutions tested were Unisol (Alcon, Fort Worth, TX) and Softwear Saline (CIBA Vision). RESULTS: The pH results for the two saline solutions and all BPSs remained in the pH range of tears (6.6-7.8). The ST of the modified BPS was significantly lower (p < 0.01) than the original non-modified BPS. Viscosity measurements ranged between 0.90 and 1.00 cP for all BPSs and saline solutions, except for the modified BPS, which had significantly higher viscosities (p < 0.001). Osmolality measurements were not significantly different (p > 0.05) between BPSs made by the same manufacturer but were significantly different compared with BPSs made by different manufacturers (p < 0.05). CONCLUSIONS: The incorporation of wetting agents and surfactants into BPSs does alter the physical properties of the BPSs, which may have clinical implications regarding initial in-eye comfort.

Immobilized hyaluronic acid containing model silicone hydrogels reduce protein adsorption.

The physical immobilization of hyaluronic acid (HA) as a wetting agent in contact lens applications was investigated using model silicone hydrogels prepared by co-polymerizing methacryloxy propyl tris (trimethylsiloxy) silane (Tris) and hydroxyethylmethacrylate (HEMA). Two different molecular weights of HA were investigated, as well as various Tris/HEMA ratios. Cross-linked HA, while only present in small amounts, increased water uptake and hydrophilicity in the materials containing 10% Tris; however, no changes were observed in the 4% Tris materials. The presence of the HA was further confirmed by increases in glass transition temperature as measured by differential scanning calorimetry. Lysozyme adsorption was dramatically decreased for materials containing cross-linked HA. The incorporation of HA, previously demonstrated to decrease protein adsorption to model conventional hydrogel materials, may have significant potential for improving the wetting and other properties of silicone hydrogel contact lens materials.

Dentine demineralization when subjected to EDTA with or without various wetting agents: a co-site digital optical microscopy study.

AIM: To analyse quantitatively the chelating ability of ethylenediaminetetraacetic acid (EDTA) and three common EDTA-based associations with wetting agents. METHODOLOGY: Twelve maxillary human molars were selected, from which 3 mm thick discs were obtained from the cervical third of the root. Following the creation of standardized smear layer co-site microscopy image sequences of the dentine surface submitted to EDTA, EDTA plus 0.1% cetavlon (Sigma Chemical Co., St Louis, MO, USA), EDTA plus 1.25% sodium lauryl ether sulphate and SmearClear (Sybron Endo, Orange, CA, USA) were obtained after several cumulative demineralization times. Sixteen images were obtained of each dentine sample for each experimental time, at 1000 x magnification. An image processing and analysis sequence was used to measure the area of open tubules for each experimental time. Thus, it was possible to follow the demineralization process and quantitatively analyse the effect of the various substances. The Student's t-test was used to assess differences between experimental groups. Results EDTA solution had the strongest effect at all experimental times whilst the association of EDTA with wetting agents showed a weaker chelating effect and this difference was statistically significant (P < 0.05). CONCLUSIONS: (i) The EDTA solution had the strongest effect at all experimental times (P < 0.05); (ii) the association of EDTA with wetting agents did not improve the chelating power of the solution; (iii) co-site optical microscopy represents a powerful approach to compare directly, longitudinally and quantitatively the ability of the chelating solutions.

The wetting agent required for swarming in Salmonella enterica serovar typhimurium is not a surfactant.

We compared the abilities of media from agar plates surrounding swarming and nonswarming cells of Salmonella enterica serovar Typhimurium to wet a nonpolar surface by measuring the contact angles of small drops. The swarming cells were wild type for chemotaxis, and the nonswarming cells were nonchemotactic mutants with motor biases that were counterclockwise (cheY) or clockwise (cheZ). The latter strains have been shown to be defective for swarming because the agar remains dry (Q. Wang, A. Suzuki, S. Mariconda, S. Porwollik, and R. M. Harshey, EMBO J. 24:2034-2042, 2005). We found no differences in the abilities of the media surrounding these cells, either wild type or mutant, to wet a low-energy surface (freshly prepared polydimethylsiloxane); although, their contact angles were smaller than that of the medium harvested from the underlying agar. So the agent that promotes wetness produced by wild-type cells is not a surfactant; it is an osmotic agent.

Friction coefficient of skin in real-time.

BACKGROUND/PURPOSE: Friction studies are useful in quantitatively investigating the skin surface. Previous studies utilized different apparatuses and materials for these investigations but there was no real-time test parameter control or monitoring. Our studies incorporated the commercially available UMT Series Micro-Tribometer, a tribology instrument that permits real-time monitoring and calculation of the important parameters in friction studies, increasing the accuracy over previous tribology and friction measurement devices used on skin. METHODS: Our friction tests were performed on four healthy volunteers and on abdominal skin samples. A stainless steel ball was pressed on to the skin with at a pre-set load and then moved across the skin at a constant velocity of 5 mm/min. The UMT continuously monitored the friction force of the skin and the normal force of the ball to calculate the friction coefficient in real-time. Tests investigated the applicability of Amonton's law, the impact of increased and decreased hydration, and the effect of the application of moisturizers. RESULTS: The friction coefficient depends on the normal load applied, and Amonton's law does not provide an accurate description for the skin surface. Application of water to the skin increased the friction coefficient and application of isopropyl alcohol decreased it. Fast acting moisturizers immediately increased the friction coefficient, but did not have the prolonged effect of the slow, long lasting moisturizers. CONCLUSION: The UMT is capable of making real-time measurements on the skin and can be used as an effective tool to study friction properties. Results from the UMT measurements agree closely with theory regarding the skin surface.

Effect of surface tension on alveolar surface area.

At fixed lung volume (VL), alterations in surface tension change alveolar surface area (S) and lung recoil (PL). Wilson (26), using data from fixed lungs (1, 9), quantified the isovolume change in S with PL. We reexamined this question in fresh excised rabbit lungs, with two important differences. First, we measured fractional changes in S by using diffuse light scattering, avoiding the potential upset of the balance of tissue and surface forces during fixation. Second, we altered surface tension by ventilating the lungs with nebulized polydimethylsiloxane, with much less residual fluid compared with lavage. We found that S decreased at low and mid VL (treatment surface tension > control) by about half of Wilson's estimates and was nearly unaffected by treatment at high VL. This suggests that with increased surface tension there is 1) greater septal retraction in lungs fixed by vascular perfusion compared with unfixed lungs and 2) a greater increase in PL and less loss of S than would have been predicted.

Wetting characteristics of media emulating gastric fluids.

A variety of dissolution media have been used to simulate the physiological environment of the gastric region. The objective of this study was to formulate and examine the wetting properties of dispersions composed of the dominant surface active species found in the stomach at physiologically relevant concentrations. Systems representing the fed and fasted states were studied and compared to other media that have been considered for use as simulated gastric fluids. Dilute bile salt/phospholipid solutions and bile salt-lipid emulsions were formulated on the basis of available physiologic data to represent the fasted and fed states, respectively. Wetting was evaluated through the determination of the surface tension and contact angle of the various solutions using poly(methyl methacrylate) (PMMA) as a model surface. Additional surfactant solutions and other biorelevant media were also tested. Data were evaluated in terms of contact angle, surface tension and the thermodynamic stages of wetting. The results indicate that solutions patterned after the composition of the GI tract have significantly different wetting properties relative to the fed and fasted states. The surfactant solutions tested were significantly better wetting agents for the surface than the physiologically representative formulations. The implications for the formulation of surfactant-based biorelevant media are discussed.

Effect of low water activity on staphylococcal enterotoxin A and B biosynthesis.

Staphylococcus aureus strains FDA 743 (staphylococcal enterotoxin A [SEA]-producing), FDA 778 (staphylococcal enterotoxin B [SEB]-producing), and S6 (SEA- and SEB-producing) were used to examine the effect of low water activity (a(w)) on SEA and SEB biosynthesis. In this report, we show that SEB production is more sensitive to low a(w) than SEA production. We also show that when proline is available as a compatible solute for S. aureus, SEB production is significantly stimulated at low a(w). This stimulatory effect was not observed when other compatible solutes (i.e., glycine betaine or carnitine) were added to low a(w) growth media. Finally, Northern blot analysis revealed that the stimulation of SEB production at low a(w) by added proline occurs at the level of transcription.

Synthesis, characterization, and platelet adhesion studies of novel aliphatic polyurethaneurea anionomers based on polydimethylsiloxane-polytetramethylene oxide soft segments.

Two novel aliphatic polyurethaneurea anionomers were synthesized based on polydimethylsiloxane (PDMS)-polytetramethylene oxide (PTMO) soft segments. The hard segments consisted of either 4,4'-methylene dicyclohexyl diisocyanate (H12MDI), sulfonic acid-containing diol and 1,4-butandiol (BD) or H12MDI, carboxylic acid-containing diol and BD. The nonionic counterpart chain extended with BD was prepared. In addition, the base nonionic polyurethaneurea containing a pure PDMS soft segment, which is denote H-D-BD, was also studied for comparison. The effects of soft segment type and ion incorporation on the physical properties, surface properties, and plateled adhesion are discussed. The ionic polyurethaneureas exhibited poor phase separation, a smaller fraction of PTMO present at the surface, and a smaller contact angle. On the other hand, it also showed a larger fraction of PDMS present at the surface and a higher water absorption value than its nonionic counterpart. H-D-BD had more phase-separated structure, a larger fraction of PDMS present at the surface, and larger contact angle but lower water absorption value than the PTMO-containing polyurethaneureas. The in vitro platelet adhesion experiments indicated that the ionic groups, especially for carboxylate, and surface enrichment PDMS soft segment could effectively inhibit platelet adhesion.

Betaine-containing toothpaste relieves subjective symptoms of dry mouth.

Subjects with dry mouth often experience irritation of the oral mucosa when using sodium lauryl sulfate containing products for oral hygiene. Betaine, or trimethylglycine, reduces skin-irritating effects of ingredients of cosmetics such as sodium lauryl sulfate. The aim of the present study was to compare the effects of a betaine-containing toothpaste with a regular toothpaste on the oral microbial flora, the condition of the oral mucosa, and subjective symptoms of dry mouth in subjects with chronic dry mouth symptoms. Thirteen subjects with chronic dry mouth symptoms and with a paraffin-stimulated salivary flow rate < or = 1 mL/min participated in the double-blind crossover study. Ten subjects had a very low salivary flow rate (< or = 0.6 mL/min). The subjects used both experimental toothpastes (with or without 4% betaine) twice a day for 2 weeks. Oral examinations and microbiologic sample collections were made at the base lines preceding the two experimental periods and at the end. Standardized questions on subjective symptoms of dry mouth were used when the subjects were interviewed at the end of the two experimental periods. No study-induced significant changes were observed in the microbiologic variables (plaque index, mutans streptococci, lactobacilli, Candida species) or in the appearance of the oral mucosa. The use of the betaine-containing toothpaste was, however, associated with a significant relief of several subjective symptoms of dry mouth. Betaine appears thus to be a promising ingredient of toothpastes in general and especially of toothpastes designed for patients with dry mouth.

Pharmacological agents with effects on voice.

Pharmacological agents with the most notable effects on voice exert their influences on the vocal tract through the autonomic nervous system. These agents do not have a profound effect on laryngeal function. Their effects are subtle, but they are important in certain groups of patients, such as professional voice users. It is essential to take a thorough history of medications being used, both by prescription and nonprescription, when evaluating patients with voice disorders. It is also important to keep in mind that idiosyncratic variations may occur in response to medications, and careful monitoring is essential when patients with voice disorders are under treatment. The importance of adequate water intake should be emphasized for general hydration and for vocal tract lubrication. Understanding the autonomic nervous system and how it is influenced by pharmacological agents makes evaluating the effect of medicines on the vocal tract simpler.

Effects of rigid gas permeable contact lens solutions on the human corneal epithelium.

In this investigation, the effects of three rigid gas permeable (RGP) contact lens wetting and soaking solutions, Boston Advance Conditioning Solution, Boston Conditioning Solution, and Allergan Wet-N-Soak Plus, were tested on the human corneal epithelium. Thirty subjects participated in three experimental sessions, during which one eye received three drops of one of these RGP solutions, while the other eye served as a control. After 10 and 30 min, corneal staining was graded in 5 areas and the eyes were photographed for a digitized analysis of staining. Our results indicate that corneas exposed to Boston Advance Conditioning Solution demonstrated significantly more fluorescein staining than control eyes at both 10 and 30 min by both methods of analysis, whereas corneas treated with the other two solutions were not significantly different from controls. The increased corneal staining noted with Boston Advance Conditioning Solution may be caused by the presence and concentration of the preservative, 0.0015% polyaminopropyl biguanide. An unforeseen result of this experiment was the relatively large number of subjects exposed to Boston Conditioning Solution and Allergan Wet-N-Soak Plus who had more corneal staining in the control eye. This may suggest that the two RGP solutions served as a barrier to fluorescein, protecting the epithelial cells from staining.