Miriam Heynen | University of Waterloo (original) (raw)

Papers by Miriam Heynen

Optometry and Vision Science, 2012

To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on sili... more To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were investigated. Lenses were incubated in four different solutions: a complex ATS consisting of various salts, lipids, proteins, and mucins, an ATS without lactoferrin (ATS w/o Lac), an ATS without lipids (ATS w/o Lip), and an ATS without lactoferrin and lipids (ATS w/o Lac & Lip), each containing 2% radiolabeled (125I) lysozyme (1.9 mg/ml). After each time point (4, 12 h and 1, 2, 3, 5, 7, 14, 21, 28 days), the amount of lysozyme per lens was quantified. After 28 days, lotrafilcon B lenses incubated in ATS deposited significantly less lysozyme (9.7 ± 1.4 μg) than when incubated in solutions not containing lactoferrin and lipids (more than 11.8 μg) (p < 0.001). Lysozyme uptake to senofilcon A lenses was higher in ATS w/o Lip (5.3 ± 0.1 μg) compared with other solutions (less than 3.9 μg) (p < 0.001). Etafilcon A lenses deposited the most lysozyme in all four solutions compared with the rest of the lens types (p < 0.001). For etafilcon A lenses, less lysozyme was deposited when incubated in ATS w/o Lip (588.6 ± 0.4 μg) compared with the other solutions (more than 642.6 μg) (p < 0.001). Omafilcon A lenses in ATS w/o Lac accumulated significantly less lysozyme (12.8 ± 1.0 μg) compared with the other solutions (more than 14.2 μg) (p < 0.001). An ATS containing lactoferrin and lipids impacts lysozyme deposition on both silicone and conventional hydrogel contact lenses. When performing in vitro experiments to study protein deposition on contact lenses, more complex models should be used to better mimic the human tear film.

Journal of the American Chemical Society, 2010

Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most ... more Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most important threat to the continued use of -lactam antibiotics. 2 The combination of -lactams with -lactamase inhibitors has proven to be a very successful strategy for overcoming resistance, but the ever-increasing prevalence of extended-spectrum -lactamases (ESBLs), carbapenemases, 3 and metallo--lactamases (MBLs) 4 compromises the effectiveness of current penicillins, cephalosporins, carbapenems, and mechanism-based -lactamase inhibitors. Consequently, there is a pressing need for new antibiotics and broad spectrum -lactamase inhibitors. 5 Cyclobutanone analogues of -lactams were explored as potential -lactamase inhibitors and antibiotics in the early 1980s. Such strategies showed limited success, however, and only weak inhibition of R-TEM-2 -lactamase, BcI -lactamase, and R61 transpeptidase was reported. No antibiotic activity was detected in vivo for any of the cyclobutanones. 6,7 As a result, the cyclobutanone system was set aside in favor of other inhibitor templates including that of the penicillanic acid sulfones.

Canadian Journal of Fisheries and Aquatic Sciences, 1987

1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci... more 1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci. 44: 2185-2191 Ciliated protozoa were sampled at discrete depths from April through October 1982 at a nearshore (38 m depth) and an offshore (178 m depth) station i n Lake Ontario. Nearshore, ciliates increased from less than 1 g-m-2 in early spring t o a maximum of about 5 (wet weight) inside the thermal bar i n late May and early June. Summer values varied around 2 g-m-2 and declined even further i n October. Offshore ciliate biomass was relatively constant; the observed range was only 2.8-6.5 g-mP2. Early spring biomass was much higher than nearshore, suggesting that a significant population persists through the winter, but the spring biomass increase was later. Although biomass concentration was greater i n the epilimnion, o n an areal basis most of the population resided i n the hypolimnion. The hypolimnetic population declined during the summer period of thermal stratification. The observed number of taxa ranged from 15 to 30 per sample. Most had distinct seasonal and vertical distributions. The majority appear to be algivores, but the role of ciliates i n the food web of Lake Ontario remains largely unknown. Their biomass is comparable with that of metazoan zooplankton, and with their higher metabolic rates, they probably perform much more of the total grazing.

Contact Lens and Anterior Eye, 2015

Optometry and Vision Science, 2011

Purpose. To quantify non-polar lipids deposited on senofilcon A silicone hydrogel contact lenses ... more Purpose. To quantify non-polar lipids deposited on senofilcon A silicone hydrogel contact lenses (J&J Acuvue OASYS) when disinfected with a no-rub one-step hydrogen peroxide system (CIBA Vision ClearCare) and a care system preserved with Polyquad & Aldox (Alcon OPTI-FREE RepleniSH). Methods. Thirty existing soft lens wearers symptomatic of dryness were enrolled into a 4-week prospective, randomized, bilateral eye (lens type), cross-over (care regimen), daily wear, double masked study. Subjects were refitted with senofilcon A lenses, which were replaced biweekly. During each period of wear, participants used either the peroxide or preserved system. After each period of wear, lenses were collected and lipid was extracted using 1.5 ml of a 2:1 chloroform:methanol solution for 3 h at 37°C. Lens extracts were analyzed for non-polar lipids [cholesterol oleate (CO), cholesterol, oleic acid (OA), triolein, and OA methyl ester] using normal phase high-performance liquid chromatography. Results. The total lipid (sum of CO and cholesterol) detected was 34 Ϯ 28 g/lens for the peroxide-based system and 22 Ϯ 21 g/lens for the system preserved with Polyquad and Aldox (p ϭ 0.029). Although there was no difference between products for cholesterol (1.4 vs. 1.3 g/lens; p ϭ 0.50), use of a system preserved with Polyquad and Aldox resulted in significantly less deposited CO (33 Ϯ 28 vs. 21 Ϯ 20 g/lens; p ϭ 0.033). Approximately, 95% of the detectable lipid deposited on the material was CO, followed by cholesterol. OA and triolein contributed Ͻ1% of the total lipid and no OA methyl ester was found on any of the lenses. Conclusions. A care system preserved with Polyquad and Aldox removed higher amounts of CO from senofilcon A contact lenses used for 2 weeks than a peroxide-based system, in soft lens wearers who were symptomatic of dry eye. (Optom Vis Sci 2011;88:1172-1179

Journal of the American Chemical Society, 2010

Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most ... more Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most important threat to the continued use of -lactam antibiotics. 2 The combination of -lactams with -lactamase inhibitors has proven to be a very successful strategy for overcoming resistance, but the ever-increasing prevalence of extended-spectrum -lactamases (ESBLs), carbapenemases, 3 and metallo--lactamases (MBLs) 4 compromises the effectiveness of current penicillins, cephalosporins, carbapenems, and mechanism-based -lactamase inhibitors. Consequently, there is a pressing need for new antibiotics and broad spectrum -lactamase inhibitors. 5 Cyclobutanone analogues of -lactams were explored as potential -lactamase inhibitors and antibiotics in the early 1980s. Such strategies showed limited success, however, and only weak inhibition of R-TEM-2 -lactamase, BcI -lactamase, and R61 transpeptidase was reported. No antibiotic activity was detected in vivo for any of the cyclobutanones. 6,7 As a result, the cyclobutanone system was set aside in favor of other inhibitor templates including that of the penicillanic acid sulfones.

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2013

To investigate the impact of lactoferrin and lipids on the kinetic denaturation of lysozyme depos... more To investigate the impact of lactoferrin and lipids on the kinetic denaturation of lysozyme deposited on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were incubated in four solutions: an ATS, ATS without lactoferrin, ATS without lipids, and ATS without lactoferrin and lipids. At various time points over a 28-day period, the percentage of active lysozyme per lens was determined using a fluorescence activity assay and an ELISA. After 28 days, the percentage of active lysozyme extracted from etafilcon A lenses in all solutions was significantly higher than all other lens materials (p < 0.001). For lotrafilcon B, senofilcon A, and omafilcon A lenses, lysozyme denaturation was greatest during the first week of incubation and before reaching a plateau (p > 0.05). The inclusion of lipids in the ATS significantly increased the lysozyme denaturation on both silicone hydrogel materials (p < 0.001), while in the presence of lactoferrin, lysozyme activity on senofilcon A lenses was significantly higher (p < 0.001). Lysozyme activity on both conventional lenses was not significantly affected by either lactoferrin or lipids (p > 0.05). Lactoferrin and lipids have an impact on the denaturation of lysozyme deposited onto silicone hydrogel contact lenses, while conventional hydrogel lenses were unaffected. Future in vitro studies should consider the impact of tear film components when investigating protein deposition and denaturation on contact lenses.

Current Eye Research, 2013

Purpose: To optimize a fluorescence-based lysozyme activity assay to investigate the conformation... more Purpose: To optimize a fluorescence-based lysozyme activity assay to investigate the conformational state of lysozyme in solution and to determine the impact of extraction and evaporation procedures and the possible interference of contact lens materials on lysozyme activity. Methods: The fluorescence-based lysozyme activity assay, Enzchek (Molecular Probes Inc, Eugene, OR) which utilizes fluorescently quenched Micrococcus lysodeikticus, was compared to the gold standard, classical lysozyme turbidity assay, using four differently concentrated lysozyme samples (20, 10, 5.0 and 2.0 ng/mL). Furthermore, six differently concentrated lysozyme samples (2.0, 1.0, 0.5, 0.25, 0.125 and 0.01 mg/mL) were quantified using the fluorescence-based assay in the presence of extraction solvents consisting of 0.2% and 0.02% trifluroacetic acid/acetonitrile and following evaporation procedures. Results: A standard curve was generated by the fluorescence-based assay ranging from 2 to 150 ng. The total active lysozyme quantified in the four lysozyme samples was not significantly different between the two assays (p40.05) and the concordance correlation coefficient was determined to be 0.995. However an average discrepancy between the two assays was found to be 0.474 ng, with the turbidity assay typically reporting higher active lysozyme measurements. The sensitivity of the fluorescence-based assay was higher than the classical turbidity assay when quantifying 20 ng or less active lysozyme. Following the extraction and evaporation procedures and the addition of lens extracts, the total active lysozyme recovered was 95% or greater. Conclusions: In comparison to the classical turbidity assay, the fluorescence-based assay is a very sensitive method, making it a favorable technique, particularly when studying contact lens materials that deposit relatively low levels of lysozyme.

Canadian Journal of Fisheries and Aquatic Sciences, 1987

1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci... more 1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci. 44: 2185-2191 Ciliated protozoa were sampled at discrete depths from April through October 1982 at a nearshore (38 m depth) and an offshore (178 m depth) station i n Lake Ontario. Nearshore, ciliates increased from less than 1 g-m-2 in early spring t o a maximum of about 5 (wet weight) inside the thermal bar i n late May and early June. Summer values varied around 2 g-m-2 and declined even further i n October. Offshore ciliate biomass was relatively constant; the observed range was only 2.8-6.5 g-mP2. Early spring biomass was much higher than nearshore, suggesting that a significant population persists through the winter, but the spring biomass increase was later. Although biomass concentration was greater i n the epilimnion, o n an areal basis most of the population resided i n the hypolimnion. The hypolimnetic population declined during the summer period of thermal stratification. The observed number of taxa ranged from 15 to 30 per sample. Most had distinct seasonal and vertical distributions. The majority appear to be algivores, but the role of ciliates i n the food web of Lake Ontario remains largely unknown. Their biomass is comparable with that of metazoan zooplankton, and with their higher metabolic rates, they probably perform much more of the total grazing.

Applied Physiology, Nutrition, and Metabolism, 2006

Optometry and vision science : official publication of the American Academy of Optometry, Jan 6, 2016

To evaluate the effect of four contemporary lens care solutions on total protein, total lysozyme,... more To evaluate the effect of four contemporary lens care solutions on total protein, total lysozyme, and active lysozyme extracted from three contact lens materials. Adapted contact lens wearers were recruited at three sites, and all subjects were randomly assigned to daily wear of either etafilcon A, galyfilcon A, or senofilcon A for 2 weeks. Four lens care solutions (Biotrue, OPTI-FREE PureMoist, RevitaLens OcuTec, and ClearCare) were used by each subject in random order with a new pair of lenses after a washout period between solutions of at least 4 days. After 2 weeks of daily wear, contact lenses were collected for analysis. Proteins were extracted from a subset of contact lenses (n = 568) and total protein, total lysozyme, and lysozyme activity were quantified using a modified Bradford assay, an enzyme-linked immunosorbent assay, and a micrococcal assay, respectively. Higher levels of total protein were extracted from etafilcon A when used with Biotrue compared to other solutions...

Molecular Vision, Dec 30, 2008

To investigate the expression of MUC16 protein in tears and conjunctival cell membranes and MUC16... more To investigate the expression of MUC16 protein in tears and conjunctival cell membranes and MUC16 mRNA in conjunctival cells of Sjogren's syndrome (SS), keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) subjects. The relationship of tear flow and soluble MUC16 concentration was also measured. Methods: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores ≤10 mm) and 26 NDE. Tear flow was measured by the Schirmer test without anesthesia for 5 min. Tears were collected using an eye-wash technique. Protein and mRNA were isolated from conjunctival epithelial cells collected via impression cytology. Soluble and membrane bound MUC16 were quantified via western blotting and MUC16 mRNA was quantified by real time qPCR.

Molecular Vision, 2010

Purpose: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and co... more Purpose: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and conjunctival epithelial cells collected from Sjogren's syndrome (SS), non-Sjogren's keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) control subjects. Methods: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores ≤10 mm) and 26 NDE. Tears were collected using an eyewash technique. Impression cytology was used to gather protein and mRNA from conjunctival epithelial cells. Soluble and membrane bound MUC1 were quantified via western blotting and MUC1 mRNA was quantified by real time qPCR.

Molecular Vision, Feb 4, 2012

To determine the impact of incubation solution composition on protein deposition to silicone hydr... more To determine the impact of incubation solution composition on protein deposition to silicone hydrogel (SH) contact lenses using a simplistic and a complex model of the tear film. Methods: Three SH materials -senofilcon A (SA), lotrafilcon B (LB), and balafilcon A (BA) -were incubated in two different solutions; Solution A was a simplistic augmented buffered saline solution containing a single protein, whereas Solution B was a complex artificial tear solution (ATS), containing the augmented buffered saline solution in addition to proteins, lipids, and mucins (pH=7.4). The proteins of interest (lysozyme, lactoferrin, albumin) were radiolabeled with Iodine-125 (2% protein of interest) and the accumulation of the conjugated protein to the lens materials was determined after 1, 7, 14, and 28 days of incubation. Protein deposition was measured using a gamma counter and the raw data were translated into absolute amounts (µg/lens) via extrapolation from standards. Results: After 28 days, lysozyme uptake was significantly lower on BA lenses when incubated in Solution A (33.7 μg) compared to Solution B (56.2 μg), p<0.001. SA lenses deposited similar amounts of lysozyme when incubated in either Solution A (2.6 μg) or Solution B (4.1 μg), p>0.05. LB lenses also deposited similar amounts of lysozyme for both solutions (Solution A: 5.0 μg, Solution B: 4.7 μg, p>0.05). After 28 days, BA lenses accumulated approximately twice the amount of lactoferrin than the other lens materials, with 30.3 μg depositing when exposed to Solution A and 22.0 μg with Solution B. The difference between the two solutions was statistically significant (p<0.001). LB materials deposited significantly greater amounts of lactoferrin when incubated in Solution A (16.6 μg) compared to Solution B (10.3 μg), p<0.001. Similar amounts of lactoferrin were accumulated onto SA lenses regardless of incubation solution composition (Solution A: 8.2 μg, Solution B: 11.2 μg, p>0.05). After 28 days, albumin deposition onto BA lenses was significantly greater when lenses were incubated in Solution B (1.7 μg) compared to Solution A (0.9 μg), p<0.001. Similar amounts of albumin were deposited on SA lenses when incubated in either solution (0.6 μg versus 0.7 μg, p>0.05). LB lenses incubated in Solution A deposited more albumin compared to Solution B (0.9 μg versus 0.6 μg), p=0.003. Discussion: Protein deposition onto SH materials varied when contact lenses were incubated in either a complex ATS compared to a single protein solution. More lysozyme accumulated onto BA lenses incubated in a complex analog of the human tear film, whereas lactoferrin deposited onto SA lenses independent of incubation solution composition. To better mimic the ex vivo environment, future studies should use more appropriate analogs of the tear film.

Molecular Vision, Dec 24, 2011

Purpose: To characterize various properties of a physiologically-relevant artificial tear solutio... more Purpose: To characterize various properties of a physiologically-relevant artificial tear solution (ATS) containing a range of tear film components within a complex salt solution, and to measure contact lens parameters and lipid deposition of a variety of contact lens materials after incubation in this ATS. Methods: A complex ATS was developed that contains a range of salts, proteins, lipids, mucin, and other tear film constituents in tear-film relevant concentrations. This ATS was tested to confirm that its pH, osmolality, surface tension, and homogeneity are similar to human tears and remain so throughout the material incubation process, for up to 4 weeks. To confirm that silicone hydrogel and conventional hydrogel contact lens materials do not alter in physical characteristics beyond what is allowed by the International Organization for Standardization (ISO) 18369-2. The diameter, center thickness, and calculated base curve were measured for five different lens materials directly out of the blister pack, after a rinse in saline and then following a two week incubation in the modified ATS. To test the ATS and the effect of its composition on lipid deposition, two lens materials were incubated in the ATS and a modified version for several time points. Both ATS solutions contained trace amounts of carbon-14 cholesterol and phosphatidylcholine, such that deposition of these specific lipids could be quantified using standard methods. Results: This ATS is a complex mixture that remains stable at physiologically relevant pH (7.3-7.6), osmolality (304-306 mmol/kg), surface tension (40-46 dynes/cm) and homogeneity over an incubation period of three weeks or more. The physical parameters of the lenses tested showed no changes beyond that allowed by the ISO guidelines. Incubations with the ATS found that balafilcon A lenses deposit significantly more cholesterol and phosphatidylcholine than omafilcon A lenses (p<0.05) and that removing lactoferrin and immunoglobulin G from the ATS can significantly decrease the mass of lipid deposited. Conclusions: This paper describes a novel complex artificial tear solution specially designed for in-vial incubation of contact lens materials. This solution was stable and did not adversely affect the physical parameters of the soft contact lenses incubated within it and showed that lipid deposition was responsive to changes in ATS composition. both a polar and non-polar lipid component . Although this layered tear film model is still favored, it is now believed that this structure is not as compartmentalized as previously thought and that the components from each layer can be found throughout the entire tear film . Soft contact lens materials, once inserted into the eye, lie in the middle of this tear film structure and are known to readily adsorb many different tear film components, including lipids, proteins, and mucins .

Molecular Vision, Jun 5, 2013

To quantify the expression of mucin 1, cell surface associated (MUC1) and mucin 16, cell surface ... more To quantify the expression of mucin 1, cell surface associated (MUC1) and mucin 16, cell surface associated (MUC16) proteins and messenger ribonucleic acid (mRNA) in a cohort of postmenopausal women (PMW), to explore the relationship between mucin expression, dry eye symptomology, and tear stability. Thirty-nine healthy PMW (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;50 years of age) were enrolled in this study. No specific inclusion criteria were used to define dry eye; instead, a range of subjects were recruited based on responses to the Allergan Ocular Surface Disease Index (OSDI) questionnaire and tear stability measurements as assessed by non-invasive tear breakup time (NITBUT). Tears were collected from the inferior tear meniscus using a disposable glass capillary tube, and total RNA and total protein were isolated from conjunctival epithelial cells collected via impression cytology. Expression of membrane-bound and soluble MUC1 and MUC16 were quantified with western blotting, and expression of MUC1 and MUC16 mRNA was assessed with real-time PCR. OSDI responses ranged from 0 to 60, and NITBUT ranged from 18.5 to 2.9 s. Only two statistically significant correlations were found: soluble MUC16 protein concentration and MUC16 mRNA expression with OSDI vision related (-0.47; p=0.01) and ocular symptom (0.39; p=0.02) subscores, respectively. Post hoc exploratory analysis on absolute expression values was performed on two subsets of subjects defined as asymptomatic (OSDI≤6, n=12) and moderate to severe symptomatic (OSDI≥20, n=12). The only significant difference between the two subgroups was a significant reduction in MUC16 mRNA expression found in the symptomatic dry eye group (1.52±1.19 versus 0.57±0.44; p=0.03). A broad exploration of mucin expression compared to either a sign (NITBUT) or symptoms of dry eye failed to reveal compelling evidence supporting a significant relationship, other than a potential association between MUC16 with specific symptoms. Furthermore, comparison of mucin protein and expression levels between the asymptomatic and moderate to severe symptomatic subgroups revealed only one significant difference, a reduction in MUC16 mRNA expression in the symptomatic subgroup.

Current eye research, Jan 27, 2015

To investigate the accuracy of I(125) radiolabeling to quantitatively determine the deposition of... more To investigate the accuracy of I(125) radiolabeling to quantitatively determine the deposition of protein onto various commercially available contact lens (CL) materials. Commercially available silicone hydrogel and conventional hydrogel CL materials were examined for times ranging from 10 s to 1 week. Adsorption of free I(125) was measured directly for the CL. The use of dialyzing labeled proteins and/or using NaI to compete with free I(125) uptake was investigated as ways to minimize effects due to free I(125). At all time points and with all lens materials, there was 0.3 μg/lens or greater of apparent mass attributable to free I(125) uptake. Dialyzing labeled proteins significantly reduced free I(125) uptake for all materials investigated. The benefit of using dialyzed protein was most prominent at shorter times, as free I(125) is continuously generated over time. Using NaI can reduce free I(125) uptake for some lens materials, but this is shown to directly affect protein deposit...

Optometry and Vision Science, 2012

To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on sili... more To investigate the impact of lactoferrin and lipids on the kinetic deposition of lysozyme on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were investigated. Lenses were incubated in four different solutions: a complex ATS consisting of various salts, lipids, proteins, and mucins, an ATS without lactoferrin (ATS w/o Lac), an ATS without lipids (ATS w/o Lip), and an ATS without lactoferrin and lipids (ATS w/o Lac &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; Lip), each containing 2% radiolabeled (125I) lysozyme (1.9 mg/ml). After each time point (4, 12 h and 1, 2, 3, 5, 7, 14, 21, 28 days), the amount of lysozyme per lens was quantified. After 28 days, lotrafilcon B lenses incubated in ATS deposited significantly less lysozyme (9.7 ± 1.4 μg) than when incubated in solutions not containing lactoferrin and lipids (more than 11.8 μg) (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Lysozyme uptake to senofilcon A lenses was higher in ATS w/o Lip (5.3 ± 0.1 μg) compared with other solutions (less than 3.9 μg) (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Etafilcon A lenses deposited the most lysozyme in all four solutions compared with the rest of the lens types (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). For etafilcon A lenses, less lysozyme was deposited when incubated in ATS w/o Lip (588.6 ± 0.4 μg) compared with the other solutions (more than 642.6 μg) (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Omafilcon A lenses in ATS w/o Lac accumulated significantly less lysozyme (12.8 ± 1.0 μg) compared with the other solutions (more than 14.2 μg) (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). An ATS containing lactoferrin and lipids impacts lysozyme deposition on both silicone and conventional hydrogel contact lenses. When performing in vitro experiments to study protein deposition on contact lenses, more complex models should be used to better mimic the human tear film.

Journal of the American Chemical Society, 2010

Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most ... more Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most important threat to the continued use of -lactam antibiotics. 2 The combination of -lactams with -lactamase inhibitors has proven to be a very successful strategy for overcoming resistance, but the ever-increasing prevalence of extended-spectrum -lactamases (ESBLs), carbapenemases, 3 and metallo--lactamases (MBLs) 4 compromises the effectiveness of current penicillins, cephalosporins, carbapenems, and mechanism-based -lactamase inhibitors. Consequently, there is a pressing need for new antibiotics and broad spectrum -lactamase inhibitors. 5 Cyclobutanone analogues of -lactams were explored as potential -lactamase inhibitors and antibiotics in the early 1980s. Such strategies showed limited success, however, and only weak inhibition of R-TEM-2 -lactamase, BcI -lactamase, and R61 transpeptidase was reported. No antibiotic activity was detected in vivo for any of the cyclobutanones. 6,7 As a result, the cyclobutanone system was set aside in favor of other inhibitor templates including that of the penicillanic acid sulfones.

Canadian Journal of Fisheries and Aquatic Sciences, 1987

1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci... more 1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci. 44: 2185-2191 Ciliated protozoa were sampled at discrete depths from April through October 1982 at a nearshore (38 m depth) and an offshore (178 m depth) station i n Lake Ontario. Nearshore, ciliates increased from less than 1 g-m-2 in early spring t o a maximum of about 5 (wet weight) inside the thermal bar i n late May and early June. Summer values varied around 2 g-m-2 and declined even further i n October. Offshore ciliate biomass was relatively constant; the observed range was only 2.8-6.5 g-mP2. Early spring biomass was much higher than nearshore, suggesting that a significant population persists through the winter, but the spring biomass increase was later. Although biomass concentration was greater i n the epilimnion, o n an areal basis most of the population resided i n the hypolimnion. The hypolimnetic population declined during the summer period of thermal stratification. The observed number of taxa ranged from 15 to 30 per sample. Most had distinct seasonal and vertical distributions. The majority appear to be algivores, but the role of ciliates i n the food web of Lake Ontario remains largely unknown. Their biomass is comparable with that of metazoan zooplankton, and with their higher metabolic rates, they probably perform much more of the total grazing.

Contact Lens and Anterior Eye, 2015

Optometry and Vision Science, 2011

Purpose. To quantify non-polar lipids deposited on senofilcon A silicone hydrogel contact lenses ... more Purpose. To quantify non-polar lipids deposited on senofilcon A silicone hydrogel contact lenses (J&J Acuvue OASYS) when disinfected with a no-rub one-step hydrogen peroxide system (CIBA Vision ClearCare) and a care system preserved with Polyquad & Aldox (Alcon OPTI-FREE RepleniSH). Methods. Thirty existing soft lens wearers symptomatic of dryness were enrolled into a 4-week prospective, randomized, bilateral eye (lens type), cross-over (care regimen), daily wear, double masked study. Subjects were refitted with senofilcon A lenses, which were replaced biweekly. During each period of wear, participants used either the peroxide or preserved system. After each period of wear, lenses were collected and lipid was extracted using 1.5 ml of a 2:1 chloroform:methanol solution for 3 h at 37°C. Lens extracts were analyzed for non-polar lipids [cholesterol oleate (CO), cholesterol, oleic acid (OA), triolein, and OA methyl ester] using normal phase high-performance liquid chromatography. Results. The total lipid (sum of CO and cholesterol) detected was 34 Ϯ 28 g/lens for the peroxide-based system and 22 Ϯ 21 g/lens for the system preserved with Polyquad and Aldox (p ϭ 0.029). Although there was no difference between products for cholesterol (1.4 vs. 1.3 g/lens; p ϭ 0.50), use of a system preserved with Polyquad and Aldox resulted in significantly less deposited CO (33 Ϯ 28 vs. 21 Ϯ 20 g/lens; p ϭ 0.033). Approximately, 95% of the detectable lipid deposited on the material was CO, followed by cholesterol. OA and triolein contributed Ͻ1% of the total lipid and no OA methyl ester was found on any of the lenses. Conclusions. A care system preserved with Polyquad and Aldox removed higher amounts of CO from senofilcon A contact lenses used for 2 weeks than a peroxide-based system, in soft lens wearers who were symptomatic of dry eye. (Optom Vis Sci 2011;88:1172-1179

Journal of the American Chemical Society, 2010

Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most ... more Antimicrobial resistance is an emerging epidemic worldwide, 1 and -lactamases represent the most important threat to the continued use of -lactam antibiotics. 2 The combination of -lactams with -lactamase inhibitors has proven to be a very successful strategy for overcoming resistance, but the ever-increasing prevalence of extended-spectrum -lactamases (ESBLs), carbapenemases, 3 and metallo--lactamases (MBLs) 4 compromises the effectiveness of current penicillins, cephalosporins, carbapenems, and mechanism-based -lactamase inhibitors. Consequently, there is a pressing need for new antibiotics and broad spectrum -lactamase inhibitors. 5 Cyclobutanone analogues of -lactams were explored as potential -lactamase inhibitors and antibiotics in the early 1980s. Such strategies showed limited success, however, and only weak inhibition of R-TEM-2 -lactamase, BcI -lactamase, and R61 transpeptidase was reported. No antibiotic activity was detected in vivo for any of the cyclobutanones. 6,7 As a result, the cyclobutanone system was set aside in favor of other inhibitor templates including that of the penicillanic acid sulfones.

Journal of Biomedical Materials Research Part B: Applied Biomaterials, 2013

To investigate the impact of lactoferrin and lipids on the kinetic denaturation of lysozyme depos... more To investigate the impact of lactoferrin and lipids on the kinetic denaturation of lysozyme deposited on silicone and conventional hydrogel lenses, using a complex artificial tear solution (ATS). Two silicone hydrogel lenses (AIR OPTIX AQUA; lotrafilcon B and ACUVUE OASYS; senofilcon A) and two conventional hydrogel lenses (ACUVUE 2; etafilcon A and PROCLEAR; omafilcon A) were incubated in four solutions: an ATS, ATS without lactoferrin, ATS without lipids, and ATS without lactoferrin and lipids. At various time points over a 28-day period, the percentage of active lysozyme per lens was determined using a fluorescence activity assay and an ELISA. After 28 days, the percentage of active lysozyme extracted from etafilcon A lenses in all solutions was significantly higher than all other lens materials (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). For lotrafilcon B, senofilcon A, and omafilcon A lenses, lysozyme denaturation was greatest during the first week of incubation and before reaching a plateau (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05). The inclusion of lipids in the ATS significantly increased the lysozyme denaturation on both silicone hydrogel materials (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001), while in the presence of lactoferrin, lysozyme activity on senofilcon A lenses was significantly higher (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; 0.001). Lysozyme activity on both conventional lenses was not significantly affected by either lactoferrin or lipids (p &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; 0.05). Lactoferrin and lipids have an impact on the denaturation of lysozyme deposited onto silicone hydrogel contact lenses, while conventional hydrogel lenses were unaffected. Future in vitro studies should consider the impact of tear film components when investigating protein deposition and denaturation on contact lenses.

Current Eye Research, 2013

Purpose: To optimize a fluorescence-based lysozyme activity assay to investigate the conformation... more Purpose: To optimize a fluorescence-based lysozyme activity assay to investigate the conformational state of lysozyme in solution and to determine the impact of extraction and evaporation procedures and the possible interference of contact lens materials on lysozyme activity. Methods: The fluorescence-based lysozyme activity assay, Enzchek (Molecular Probes Inc, Eugene, OR) which utilizes fluorescently quenched Micrococcus lysodeikticus, was compared to the gold standard, classical lysozyme turbidity assay, using four differently concentrated lysozyme samples (20, 10, 5.0 and 2.0 ng/mL). Furthermore, six differently concentrated lysozyme samples (2.0, 1.0, 0.5, 0.25, 0.125 and 0.01 mg/mL) were quantified using the fluorescence-based assay in the presence of extraction solvents consisting of 0.2% and 0.02% trifluroacetic acid/acetonitrile and following evaporation procedures. Results: A standard curve was generated by the fluorescence-based assay ranging from 2 to 150 ng. The total active lysozyme quantified in the four lysozyme samples was not significantly different between the two assays (p40.05) and the concordance correlation coefficient was determined to be 0.995. However an average discrepancy between the two assays was found to be 0.474 ng, with the turbidity assay typically reporting higher active lysozyme measurements. The sensitivity of the fluorescence-based assay was higher than the classical turbidity assay when quantifying 20 ng or less active lysozyme. Following the extraction and evaporation procedures and the addition of lens extracts, the total active lysozyme recovered was 95% or greater. Conclusions: In comparison to the classical turbidity assay, the fluorescence-based assay is a very sensitive method, making it a favorable technique, particularly when studying contact lens materials that deposit relatively low levels of lysozyme.

Canadian Journal of Fisheries and Aquatic Sciences, 1987

1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci... more 1987. Seasonal and vertical distribution of Ciliophora i n Lake Ontario. Can. 1. Fish. Aquat. Sci. 44: 2185-2191 Ciliated protozoa were sampled at discrete depths from April through October 1982 at a nearshore (38 m depth) and an offshore (178 m depth) station i n Lake Ontario. Nearshore, ciliates increased from less than 1 g-m-2 in early spring t o a maximum of about 5 (wet weight) inside the thermal bar i n late May and early June. Summer values varied around 2 g-m-2 and declined even further i n October. Offshore ciliate biomass was relatively constant; the observed range was only 2.8-6.5 g-mP2. Early spring biomass was much higher than nearshore, suggesting that a significant population persists through the winter, but the spring biomass increase was later. Although biomass concentration was greater i n the epilimnion, o n an areal basis most of the population resided i n the hypolimnion. The hypolimnetic population declined during the summer period of thermal stratification. The observed number of taxa ranged from 15 to 30 per sample. Most had distinct seasonal and vertical distributions. The majority appear to be algivores, but the role of ciliates i n the food web of Lake Ontario remains largely unknown. Their biomass is comparable with that of metazoan zooplankton, and with their higher metabolic rates, they probably perform much more of the total grazing.

Applied Physiology, Nutrition, and Metabolism, 2006

Optometry and vision science : official publication of the American Academy of Optometry, Jan 6, 2016

To evaluate the effect of four contemporary lens care solutions on total protein, total lysozyme,... more To evaluate the effect of four contemporary lens care solutions on total protein, total lysozyme, and active lysozyme extracted from three contact lens materials. Adapted contact lens wearers were recruited at three sites, and all subjects were randomly assigned to daily wear of either etafilcon A, galyfilcon A, or senofilcon A for 2 weeks. Four lens care solutions (Biotrue, OPTI-FREE PureMoist, RevitaLens OcuTec, and ClearCare) were used by each subject in random order with a new pair of lenses after a washout period between solutions of at least 4 days. After 2 weeks of daily wear, contact lenses were collected for analysis. Proteins were extracted from a subset of contact lenses (n = 568) and total protein, total lysozyme, and lysozyme activity were quantified using a modified Bradford assay, an enzyme-linked immunosorbent assay, and a micrococcal assay, respectively. Higher levels of total protein were extracted from etafilcon A when used with Biotrue compared to other solutions...

Molecular Vision, Dec 30, 2008

To investigate the expression of MUC16 protein in tears and conjunctival cell membranes and MUC16... more To investigate the expression of MUC16 protein in tears and conjunctival cell membranes and MUC16 mRNA in conjunctival cells of Sjogren's syndrome (SS), keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) subjects. The relationship of tear flow and soluble MUC16 concentration was also measured. Methods: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores ≤10 mm) and 26 NDE. Tear flow was measured by the Schirmer test without anesthesia for 5 min. Tears were collected using an eye-wash technique. Protein and mRNA were isolated from conjunctival epithelial cells collected via impression cytology. Soluble and membrane bound MUC16 were quantified via western blotting and MUC16 mRNA was quantified by real time qPCR.

Molecular Vision, 2010

Purpose: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and co... more Purpose: To quantify and compare human mucin 1 (MUC1) protein and mRNA expression in tears and conjunctival epithelial cells collected from Sjogren's syndrome (SS), non-Sjogren's keratoconjunctivitus sicca (KCS) and non-dry eyed (NDE) control subjects. Methods: Seventy-six subjects were recruited for this study: 25 SS (confirmed via American-European Consensus Criteria 2002), 25 KCS (confirmed by symptoms and Schirmer scores ≤10 mm) and 26 NDE. Tears were collected using an eyewash technique. Impression cytology was used to gather protein and mRNA from conjunctival epithelial cells. Soluble and membrane bound MUC1 were quantified via western blotting and MUC1 mRNA was quantified by real time qPCR.

Molecular Vision, Feb 4, 2012

To determine the impact of incubation solution composition on protein deposition to silicone hydr... more To determine the impact of incubation solution composition on protein deposition to silicone hydrogel (SH) contact lenses using a simplistic and a complex model of the tear film. Methods: Three SH materials -senofilcon A (SA), lotrafilcon B (LB), and balafilcon A (BA) -were incubated in two different solutions; Solution A was a simplistic augmented buffered saline solution containing a single protein, whereas Solution B was a complex artificial tear solution (ATS), containing the augmented buffered saline solution in addition to proteins, lipids, and mucins (pH=7.4). The proteins of interest (lysozyme, lactoferrin, albumin) were radiolabeled with Iodine-125 (2% protein of interest) and the accumulation of the conjugated protein to the lens materials was determined after 1, 7, 14, and 28 days of incubation. Protein deposition was measured using a gamma counter and the raw data were translated into absolute amounts (µg/lens) via extrapolation from standards. Results: After 28 days, lysozyme uptake was significantly lower on BA lenses when incubated in Solution A (33.7 μg) compared to Solution B (56.2 μg), p<0.001. SA lenses deposited similar amounts of lysozyme when incubated in either Solution A (2.6 μg) or Solution B (4.1 μg), p>0.05. LB lenses also deposited similar amounts of lysozyme for both solutions (Solution A: 5.0 μg, Solution B: 4.7 μg, p>0.05). After 28 days, BA lenses accumulated approximately twice the amount of lactoferrin than the other lens materials, with 30.3 μg depositing when exposed to Solution A and 22.0 μg with Solution B. The difference between the two solutions was statistically significant (p<0.001). LB materials deposited significantly greater amounts of lactoferrin when incubated in Solution A (16.6 μg) compared to Solution B (10.3 μg), p<0.001. Similar amounts of lactoferrin were accumulated onto SA lenses regardless of incubation solution composition (Solution A: 8.2 μg, Solution B: 11.2 μg, p>0.05). After 28 days, albumin deposition onto BA lenses was significantly greater when lenses were incubated in Solution B (1.7 μg) compared to Solution A (0.9 μg), p<0.001. Similar amounts of albumin were deposited on SA lenses when incubated in either solution (0.6 μg versus 0.7 μg, p>0.05). LB lenses incubated in Solution A deposited more albumin compared to Solution B (0.9 μg versus 0.6 μg), p=0.003. Discussion: Protein deposition onto SH materials varied when contact lenses were incubated in either a complex ATS compared to a single protein solution. More lysozyme accumulated onto BA lenses incubated in a complex analog of the human tear film, whereas lactoferrin deposited onto SA lenses independent of incubation solution composition. To better mimic the ex vivo environment, future studies should use more appropriate analogs of the tear film.

Molecular Vision, Dec 24, 2011

Purpose: To characterize various properties of a physiologically-relevant artificial tear solutio... more Purpose: To characterize various properties of a physiologically-relevant artificial tear solution (ATS) containing a range of tear film components within a complex salt solution, and to measure contact lens parameters and lipid deposition of a variety of contact lens materials after incubation in this ATS. Methods: A complex ATS was developed that contains a range of salts, proteins, lipids, mucin, and other tear film constituents in tear-film relevant concentrations. This ATS was tested to confirm that its pH, osmolality, surface tension, and homogeneity are similar to human tears and remain so throughout the material incubation process, for up to 4 weeks. To confirm that silicone hydrogel and conventional hydrogel contact lens materials do not alter in physical characteristics beyond what is allowed by the International Organization for Standardization (ISO) 18369-2. The diameter, center thickness, and calculated base curve were measured for five different lens materials directly out of the blister pack, after a rinse in saline and then following a two week incubation in the modified ATS. To test the ATS and the effect of its composition on lipid deposition, two lens materials were incubated in the ATS and a modified version for several time points. Both ATS solutions contained trace amounts of carbon-14 cholesterol and phosphatidylcholine, such that deposition of these specific lipids could be quantified using standard methods. Results: This ATS is a complex mixture that remains stable at physiologically relevant pH (7.3-7.6), osmolality (304-306 mmol/kg), surface tension (40-46 dynes/cm) and homogeneity over an incubation period of three weeks or more. The physical parameters of the lenses tested showed no changes beyond that allowed by the ISO guidelines. Incubations with the ATS found that balafilcon A lenses deposit significantly more cholesterol and phosphatidylcholine than omafilcon A lenses (p<0.05) and that removing lactoferrin and immunoglobulin G from the ATS can significantly decrease the mass of lipid deposited. Conclusions: This paper describes a novel complex artificial tear solution specially designed for in-vial incubation of contact lens materials. This solution was stable and did not adversely affect the physical parameters of the soft contact lenses incubated within it and showed that lipid deposition was responsive to changes in ATS composition. both a polar and non-polar lipid component . Although this layered tear film model is still favored, it is now believed that this structure is not as compartmentalized as previously thought and that the components from each layer can be found throughout the entire tear film . Soft contact lens materials, once inserted into the eye, lie in the middle of this tear film structure and are known to readily adsorb many different tear film components, including lipids, proteins, and mucins .

Molecular Vision, Jun 5, 2013

To quantify the expression of mucin 1, cell surface associated (MUC1) and mucin 16, cell surface ... more To quantify the expression of mucin 1, cell surface associated (MUC1) and mucin 16, cell surface associated (MUC16) proteins and messenger ribonucleic acid (mRNA) in a cohort of postmenopausal women (PMW), to explore the relationship between mucin expression, dry eye symptomology, and tear stability. Thirty-nine healthy PMW (&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;50 years of age) were enrolled in this study. No specific inclusion criteria were used to define dry eye; instead, a range of subjects were recruited based on responses to the Allergan Ocular Surface Disease Index (OSDI) questionnaire and tear stability measurements as assessed by non-invasive tear breakup time (NITBUT). Tears were collected from the inferior tear meniscus using a disposable glass capillary tube, and total RNA and total protein were isolated from conjunctival epithelial cells collected via impression cytology. Expression of membrane-bound and soluble MUC1 and MUC16 were quantified with western blotting, and expression of MUC1 and MUC16 mRNA was assessed with real-time PCR. OSDI responses ranged from 0 to 60, and NITBUT ranged from 18.5 to 2.9 s. Only two statistically significant correlations were found: soluble MUC16 protein concentration and MUC16 mRNA expression with OSDI vision related (-0.47; p=0.01) and ocular symptom (0.39; p=0.02) subscores, respectively. Post hoc exploratory analysis on absolute expression values was performed on two subsets of subjects defined as asymptomatic (OSDI≤6, n=12) and moderate to severe symptomatic (OSDI≥20, n=12). The only significant difference between the two subgroups was a significant reduction in MUC16 mRNA expression found in the symptomatic dry eye group (1.52±1.19 versus 0.57±0.44; p=0.03). A broad exploration of mucin expression compared to either a sign (NITBUT) or symptoms of dry eye failed to reveal compelling evidence supporting a significant relationship, other than a potential association between MUC16 with specific symptoms. Furthermore, comparison of mucin protein and expression levels between the asymptomatic and moderate to severe symptomatic subgroups revealed only one significant difference, a reduction in MUC16 mRNA expression in the symptomatic subgroup.

Current eye research, Jan 27, 2015

To investigate the accuracy of I(125) radiolabeling to quantitatively determine the deposition of... more To investigate the accuracy of I(125) radiolabeling to quantitatively determine the deposition of protein onto various commercially available contact lens (CL) materials. Commercially available silicone hydrogel and conventional hydrogel CL materials were examined for times ranging from 10 s to 1 week. Adsorption of free I(125) was measured directly for the CL. The use of dialyzing labeled proteins and/or using NaI to compete with free I(125) uptake was investigated as ways to minimize effects due to free I(125). At all time points and with all lens materials, there was 0.3 μg/lens or greater of apparent mass attributable to free I(125) uptake. Dialyzing labeled proteins significantly reduced free I(125) uptake for all materials investigated. The benefit of using dialyzed protein was most prominent at shorter times, as free I(125) is continuously generated over time. Using NaI can reduce free I(125) uptake for some lens materials, but this is shown to directly affect protein deposit...