EFFECT OF MEIBOMIAN GLAND EXPRESSION ON TEAR LIPID LAYER STRUCTURE AND STABILITY

Cytolytic protein (Cyt) is a member of insecticidal proteins produced by Bacillus thuringiensis. Cyt protein has activity against insect cells and mammalian cells, which differ in lipid and cholesterol composition. This study presents the lipid binding behavior of Cyt2Aa2 protein on model membranes containing different levels of cholesterol content by combining Quartz Crystal Microbalance with Dissipation (QCM-D) and Atomic Force Microscopy (AFM). QCM-D results revealed that cholesterol enhances the binding rate of Cyt2Aa2 protein onto lipid bilayers. In addition, the thicker lipid bilayer was observed for the highest cholesterol content. These results were confirmed by AFM. The analysis of protein surface coverage as a function of time showed a slower process for 5:0 and 5:0.2 (POPC:Chol) ratios than for 5:1 and 5:2 (POPC:Chol) ratios. Significantly, the Cyt2Aa2-lipid binding behavior and the protein–lipid layer were different for the 5:3 (POPC:Chol) ratio. Furthermore, AFM images revealed a transformation of Cyt2Aa2/lipid layer structure from strip pattern to ring shape structures (which showed a strong repulsion with AFM tip). In summary, cholesterol increases the binding rate and alters the lipid binding behavior of Cyt2Aa2 protein, although it is not required for Cyt2Aa2 protein binding onto lipid bilayers.

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Ocular surface analysis: A comparison between the LipiView® II and IDRA®

European Journal of Ophthalmology ◽

10.1177/1120672120969035 ◽

2020 ◽

pp. 112067212096903

Author(s):

Jeong Min Lee ◽

Young Joon Jeon ◽

Kook Young Kim ◽

Kyu-Yeon Hwang ◽

Young-A Kwon ◽

...

Keyword(s):

Observational Study ◽

Layer Thickness ◽

Surface Analysis ◽

Ocular Surface ◽

Random Order ◽

Meibomian Gland ◽

Lipid Layer ◽

Cross Sectional ◽

Single Visit ◽

Significant Difference

Purpose: To compare the lipid layer thickness (LLT), meibomian gland (MG) dropouts, and blinking pattern determined by the analysis of images acquired from the LipiView® II (LVII) and the IDRA® Ocular surface analyzer. Methods: A cross-sectional single-visit observational study was conducted. The LLT (minimum, maximum, and average), percentages of MG dropouts, and partial blink rates (PBR) were taken from both eyes of 47 participants using LVII and IDRA. Both devices were used to image the inferior eyelid of each participant in a random order. Results: Forty-seven participants (mean age 56.77 ± 14.47 (21–79) years, 66% female) completed the study. There was no significant difference in LLT between the two devices. A significant difference in percentages of MG dropouts was obtained between the LVII (36.51 ± 17.53) and the IDRA (45.36 ± 21.87), p = 0.003). There was also a significant difference in PBR between the LVII (0.51 ± 0.37) and the IDRA (0.23 ± 0.27), p < 0.001). Conclusion: No significant difference in LLT was obtained between LVII and IDRA. IDRA had a significantly lesser percentage of MG dropout and a higher PBR compared to LVII. These results indicate that these devices should not be used interchangeably for the evaluation of MG dropouts and PBR.

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Ocular Surface Workup in Patients with Meibomian Gland Dysfunction Treated with Intense Regulated Pulsed Light

Diagnostics ◽

10.3390/diagnostics9040147 ◽

2019 ◽

Vol 9 (4) ◽

pp. 147 ◽

Cited By ~ 4

Author(s):

Luca Vigo ◽

Leonardo Taroni ◽

Federico Bernabei ◽

Marco Pellegrini ◽

Stefano Sebastiani ◽

...

Keyword(s):

Signs And Symptoms ◽

Meibomian Gland ◽

Response To Treatment ◽

Meibomian Gland Dysfunction ◽

Pulsed Light ◽

Lipid Layer ◽

Non Invasive ◽

Lower Baseline ◽

Ocular Discomfort ◽

Break Up

The purpose of the present study was to evaluate changes of signs and symptoms in patients with meibomian gland dysfunction (MGD) treated with intense regulated pulsed light (IRPL), and to further investigate which parameter could predict positive outcomes of the procedure. Twenty-eight patients who bilaterally received three IRPL sessions at day 1, 15, and 45 satisfied the criteria and were included in the study. Non-invasive break-up time (NIBUT), lipid layer thickness (LLT), meibography, tear osmolarity, and ocular discomfort symptoms were measured before and 30 days after the last IRPL session. Qualified or complete success was defined in the presence of an improvement of symptoms associated with an increase of NIBUT (< or ≥ 20%). After IRPL treatment, median NIBUT and LLT increased from 7.5 to 10.2 s and 2.0 to 3.0, respectively (p <0.001); tear osmolarity decreased from 304.0 to 301.0 mOsm/L (p = 0.002). Subjective symptoms improved after IRPL in 26 patients. Qualified success was reached in 34 eyes, while complete success in 16 eyes. Patients with lower baseline break-up time (BUT) values showed better response to treatment (p = 0.04). In conclusion, IRPL improved signs and symptoms in MGD patients, while lower baseline NIBUT values were predictive of better response to IRPL.

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