scholarly journals The Role of Endogenous Proteins on the Emulsification of Silicone Oils Used in Vitreoretinal Surgery

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Irene Nepita ◽  
Rodolfo Repetto ◽  
Jan O. Pralits ◽  
Mario R. Romano ◽  
Francesca Ravera ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Serum Proteins ◽  
Vitreous Body ◽  
Vitreoretinal Surgery ◽  
It Value ◽  
Silicone Oils ◽  
Dilational Viscoelasticity ◽  
Endogenous Proteins ◽  
The Stability

The present work is aimed at investigating the chemicophysical properties of the interface between silicone oils (SOs) used in vitreoretinal surgery and aqueous solutions, in the presence of surfactant biomolecules. Such molecules are thought to play an important role in the formation of SO emulsions in vitrectomised eyes, in which the natural vitreous body has been replaced with a SO. In particular, we have measured the interfacial tension (IT) and the interfacial dilational viscoelasticity (DV) of the interface between SO (Siluron 1000) and serum proteins (albumin and γ-globulins) at various concentrations in a Dulbecco alkaline buffer. The equilibrium IT value is relevant for the onset of emulsification, and the DV influences the stability of an emulsion, once formed. The study is complemented by preliminary emulsification tests. The experimental results show that, when proteins are dissolved in the aqueous solution, the rheological properties of the interface change. The IT decreases significantly for physiological protein concentrations, and the DV modulus achieves high values, even for small protein concentrations. The emulsification tests confirm that, in the presence of proteins, emulsions are stable on the time scale of months. We conclude that the measured values of IT in the presence of serum proteins are compatible with the promotion of droplet formation, which, in addition, are expected to be stable against coalescence. Adsorption of biomolecules at the interface with the SO is, therefore, likely to play an important role in the generation of an emulsion in eyes subjected to vitrectomy. These findings are relevant to identify strategies to avoid or control the formation of emulsions in eyes.

Impact of inorganic buffering ions on the stability of Fe(vi) in aqueous solution: role of the carbonate ion

2016 ◽  
Vol 18 (6) ◽  
pp. 4415-4422 ◽  
Author(s):  
Michal Kolář ◽  
Petr Novák ◽  
Karolína M. Šišková ◽  
Libor Machala ◽  
Ondřej Malina ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Carbonate Ion ◽  
The Stability ◽  
Ph Range

The study presents a systematic kinetics investigation of the decay of ferrate(vi) in the presence of inorganic buffering ions (borate, phosphate, and carbonate) at a pH range from 6.0 to 9.0.

scholarly journals Intraventricular Silicone Oil: An Imitator

2016 ◽  
Vol 2 (3) ◽  
pp. 48-49
Author(s):  
Ajit Reddy ◽  
Manjunath Narayanappa ◽  
Anil K Shukla ◽  
Annitha E Jayamohan
Keyword(s):  
Computed Tomography ◽  
Cerebrospinal Fluid ◽  
Rare Case ◽  
Silicone Oil ◽  
Vitreoretinal Surgery ◽  
Silicon Oil ◽  
Silicone Oils ◽  
Oil Seepage ◽  
The Brain

ABSTRACT Introduction Silicone oils are used in vitreoretinal surgery and it helps in maintaining the shape and fullness of the orbital globe. Rarely, they may get leaked from the orbit and may track to the brain in cerebrospinal fluid spaces like cisterns, ventricles. This can be documented by computed tomography with hyperdense oil. We are presenting a very rare case of the orbital silicon oil seepage into the ventricle. We report the role of multidetector computed tomography to see silicone oil migrating from orbits to the brain. Not many cases are reported in the literature. How to site this article Reddy AK, Narayanappa M, Shukla AK, Jayamohan AE. Intraventricular Silicone Oil: An Imitator. J Med Sci 2016;2(3):48-49.

scholarly journals Silicone oil: physical properties and clinical use (a literature review)

The Eye ◽  
2020 ◽  
Vol 22 (4(132)) ◽  
pp. 42-49
Author(s):  
A. A. Tashmukhamedov
Keyword(s):  
Literature Review ◽  
Silicone Oil ◽  
Optimal Schedule ◽  
Vitreous Body ◽  
Vitreoretinal Surgery ◽  
Optimal Choice ◽  
Eye Injuries ◽  
Giant Retinal Tear ◽  
Silicone Oils ◽  
Surgical Bleeding

Introduction. In modern vitreoretinal surgery, silicone oil is used for replacing the vitreous body during vitrectomy. This surgery is performed to treat retinal detachment, proliferative retinopathy, giant retinal tears and severe eye injuries. In this regard, it seems especially relevant to provide a description of the physical characteristics of silicone oils that determine the choice of surgeons.Purpose. To study indications for the use of silicone oil tamponade as well as possible complications associated with its use based on a literature review and own research.Materials and methods. We analyzed literature on PubMed, eLibrary, and Medline over the past 30 years. Overall, 34 sources of literature were reviewed, including results of our own clinical studies.Results. Literature review has shown that silicone oils are very useful as a permanent tamponade. Although gas tamponade can be used for giant retinal tear management, silicone oils are used for minimizing the risk of post-surgical bleeding and reattach detached retinas in case of severe eye injuries. One of the main issues related to the use of silicone oils is the post-surgical increase in IOP. To reduce the risk of such complication, we have proposed methods of infusion and optimal schedule of silicone oil removal.Conclusion. Silicone oil is the optimal choice for treating most retinal diseases and improving their prognosis. An important criterion for choice of silicone oil is the time that is required for tamponade.

scholarly journals The effect of serum proteins on dynamic interfacial properties of silicone oils in vitrectomized eyes

2018 ◽  
Vol 2 (2) ◽  
pp. 52-57
Author(s):  
Irene Nepita ◽  
Libero Liggieri ◽  
Eva Santini ◽  
Francesca Ravera ◽  
Mario R. Romano ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Surface Tension ◽  
Aqueous Humor ◽  
Serum Proteins ◽  
Silicone Oil ◽  
Interfacial Properties ◽  
Quantitative Information ◽  
Silicone Oils ◽  
Natural Surfactants ◽  
Viscoelastic Modulus

The formation and stability of emulsions in vitrectomized eyes is linked to the properties of the silicone oil-aqueous humor interface, in particular the surface tension. In the presence of natural surfactants, such as serum and plasma, the value of the surface tension is likely to change, but little quantitative information is presently available.To this end, we perform accurate experiments measuring the interfacialproperties of the Siluron 1000 (Fluoron GmbH, Ulm, Germany) silicone oil with an aqueous solution in the presence of endogenous-like proteins. It is found that the surface tension is significantly reduced when physiologically realistic concentrations are used. Moreover, the values obtained for the dilational viscoelastic modulus are compatible with the formation of stable emulsions.

A Statistical Study of Process Variables to Optimize a High Speed Curtain Coater: Part I

TAPPI Journal ◽  
2009 ◽  
Vol 8 (1) ◽  
pp. 20-26 ◽  
Author(s):  
PEEYUSH TRIPATHI ◽  
MARGARET JOYCE ◽  
PAUL D. FLEMING ◽  
MASAHIRO SUGIHARA
Keyword(s):  
Boundary Layer ◽  
Experimental Design ◽  
High Speed ◽  
Statistical Study ◽  
Process Variables ◽  
High Speeds ◽  
The Stability ◽  
Air Removal ◽  
Removal System

Using an experimental design approach, researchers altered process parameters and material prop-erties to stabilize the curtain of a pilot curtain coater at high speeds. Part I of this paper identifies the four significant variables that influence curtain stability. The boundary layer air removal system was critical to the stability of the curtain and base sheet roughness was found to be very important. A shear thinning coating rheology and higher curtain heights improved the curtain stability at high speeds. The sizing of the base sheet affected coverage and cur-tain stability because of its effect on base sheet wettability. The role of surfactant was inconclusive. Part II of this paper will report on further optimization of curtain stability with these four variables using a D-optimal partial-facto-rial design.

The Role of Hydrophobicity in the Stability and pH-Switchability of (RXDX)4 and Coumarin-RXDX Conjugate β-Sheets

2020 ◽  
Author(s):  
Ryan Weber ◽  
Martin McCullagh
Keyword(s):  
Biological Imaging ◽  
Ph Sensing ◽  
Hydrophobic Residue ◽  
Ideal Candidate ◽  
Self Assembling ◽  
Sensing Applications ◽  
Β Sheets ◽  
The Stability ◽  
Dynamics Simulations

<p>pH-switchable, self-assembling materials are of interest in biological imaging and sensing applications. Here we propose that combining the pH-switchability of RXDX (X=Ala, Val, Leu, Ile, Phe) peptides and the optical properties of coumarin creates an ideal candidate for these materials. This suggestion is tested with a thorough set of all-atom molecular dynamics simulations. We first investigate the dependence of pH-switchabiliy on the identity of the hydrophobic residue, X, in the bare (RXDX)<sub>4</sub> systems. Increasing the hydrophobicity stabilizes the fiber which, in turn, reduces the pH-switchabilty of the system. This behavior is found to be somewhat transferable to systems in which a single hydrophobic residue is replaced with a coumarin containing amino acid. In this case, conjugates with X=Ala are found to be unstable and both pHs while conjugates with X=Val, Leu, Ile and Phe are found to form stable β-sheets at least at neutral pH. The (RFDF)<sub>4</sub>-coumarin conjugate is found to have the largest relative entropy value of 0.884 +/- 0.001 between neutral and acidic coumarin ordering distributions. Thus, we posit that coumarin-(RFDF)<sub>4</sub> containing peptide sequences are ideal candidates for pH-sensing bioelectronic materials.</p>

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