Dynamics of proteins: Light scattering study of dilute and dense colloidal suspensions of eye lens homogenates

We report a dynamic light scattering study on protein suspensions of bovine lens homogenates at conditions (pH and ionic strength) similar to the physiological ones. Light scattering data were collected at two temperatures, 20 oC and 37 oC, over a wide range of concentrations from the very dilute limit up to the dense regime approaching to the physiological lens concentration. A comparison with experimental data from intact bovine lenses was advanced revealing differences between dispersions and lenses at similar concentrations. In the dilute regime two scattering entities were detected and identified with the long-time, self-diffusion modes of alpha-crystallins and their aggregates, which naturally exist in lens nucleus. Self-diffusion coefficients are temperature insensitive, whereas the collective diffusion coefficient depends strongly on temperature revealing a reduction of the net repulsive interparticle forces with lowering temperature. While there are no rigorous theoretical approaches on particle diffusion properties for multi-component, non-ideal hard-sphere, polydispersed systems, as the suspensions studied here, a discussion of the volume fraction dependence of the long-time, self-diffusion coefficient in the context of existing theoretical approaches was undertaken. This study is purported to provide some insight into the complex light scattering pattern of intact lenses and the interactions between the constituent proteins that are responsible for lens transparency. This would lead to understand basic mechanisms of specific protein interactions that lead to lens opacification (cataract) under pathological conditions.Comment: To appear in J. Chem. Phy

Nonpreserved amniotic membrane transplantation for bilateral toxic keratopathy caused by topical anesthetic abuse: a case report

<p>Abstract</p> <p>Introduction</p> <p>Corneal damage associated with abuse of topical anesthetics is a rare clinic entity. Topical anesthetic abuse is one of the causes of ring keratitis. Ring keratitis is easily overlooked because it can mimic acanthamoeba keratitis or other infectious keratitis. The outcome is often poor, leading to persistent epithelial defects, corneal scarring, and perforations.</p> <p>Case presentation</p> <p>We report the clinical presentation, diagnosis, and treatment of a 65-year-old Caucasian man, who worked as a health care worker, with bilateral toxic keratopathy caused by topical anesthetic abuse. Nonpreserved amniotic membrane transplantation was performed for both eyes of the patient.</p> <p>Conclusion</p> <p>It is important to identify and treat patients who abuse topical anesthetics before permanent vision loss ensues. Nonpreserved amniotic membrane transplantation may be useful in relieving pain and improving corneal surface in anesthetic agent abusers.</p

Topical non-steroidal anti-inflammatory drugs for analgesia in traumatic corneal abrasions

BACKGROUND: Traumatic corneal abrasions are relatively common and there is a lack of consensus about analgesia in their management. It is therefore important to document the clinical efficacy and safety profile of topical ophthalmic non-steroidal anti-inflammatory drugs (NSAIDs) in the management of traumatic corneal abrasions. OBJECTIVES: To identify and evaluate all randomised controlled trials (RCTs) comparing the use of topical NSAIDs with placebo or any alternative analgesic interventions in adults with traumatic corneal abrasions (including corneal abrasions arising from foreign body removal), to reduce pain, and its effects on healing time. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2017, Issue 2), MEDLINE Ovid (1946 to 30 March 2017), Embase Ovid (1947 to 30 March 2017), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 30 March 2017), OpenGrey (System for Information on Grey Literature in Europe) (www.opengrey.eu/); searched 30 March 2017, ZETOC (1993 to 30 March 2017), the ISRCTN registry (www.isrctn.com/editAdvancedSearch); searched 30 March 2017, ClinicalTrials.gov (www.clinicaltrials.gov); searched 30 March 2017 and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en); searched 30 March 2017. We did not use any date or language restrictions in the electronic searches for trials.We checked the reference lists of identified trials to search for further potentially relevant studies. SELECTION CRITERIA: RCTs comparing topical NSAIDs to placebo or any alternative analgesic interventions in adults with traumatic corneal abrasions. DATA COLLECTION AND ANALYSIS: Two review authors independently performed data extraction and assessed risks of bias in the included studies. We rated the certainty of the evidence using GRADE. MAIN RESULTS: We included nine studies that met the inclusion criteria, reporting data on 637 participants.The studies took place in the UK, USA, Israel, Italy, France and Portugal. These studies compared five types of topical NSAIDs (0.1% indomethacin, 0.03% flurbiprofen, 0.5% ketorolac, 1% indomethacin, 0.1% diclofenac) to control (consisting of standard care and in four studies used placebo eye drops). Overall, the studies were at an unclear or high risk of bias (particularly selection and reporting bias). None of the included studies reported the primary outcome measures of this review, namely participant-reported pain intensity reduction of 30% or more or 50% or more at 24 hours. Four trials, that included data on 481 participants receiving NSAIDs or control (placebo/standard care), reported on the use of 'rescue' analgesia at 24 hours as a proxy measure of pain control. Topical NSAIDs were associated with a reduction in the need for oral analgesia compared with control (risk ratio (RR) 0.46, 95% confidence interval (CI) 0.34 to 0.61; low-certainty evidence). Approximately 4 out of 10 people in the control group used rescue analgesia at 24 hours. No data were available on the use of analgesia at 48 or 72 hours.One trial (28 participants) reported on the proportion of abrasions healed after 24 and 48 hours. These outcomes were similar in both arms of the trial. (at 24 hours RR 1.00 (0.81 to 1.23); at 48 hours RR 1.00 (0.88 to 1.14); low-certainty evidence). In the control group nine out of 10 abrasions were healed within 24 hours and all were healed by 48 hours. Complications of corneal abrasions were reported in 6 studies (609 participants) and were infrequently reported (4 complications, 1 in NSAID groups (recurrent corneal erosion) and 3 in control groups (2 recurrent corneal erosions and 1 corneal abscess), very low-certainty evidence). Possible drug-related adverse events (AEs) were reported in two trials (163 participants), with the number of adverse events low (4 AEs, 3 in NSAID group, including discomfort/photophobia on instillation, conjunctival hyperaemia and urticaria, and 1 in the control group, corneal abscess) very low-certainty evidence. AUTHORS' CONCLUSIONS: The findings of the included studies do not provide strong evidence to support the use of topical NSAIDs in traumatic corneal abrasions. This is important, since NSAIDs are associated with a higher cost compared to oral analgesics. None of the trials addressed our primary outcome measure of participant-reported pain intensity reduction of 30% or more or 50% or more at 24 hours

Dynamic light scattering study on phase separation of a protein-water mixture: Application on cold cataract development in the ocular lens

We present a detailed dynamic light scattering study on the phase separation in the ocular lens emerging during cold cataract development. Cold cataract is a phase separation effect that proceeds via spinodal decomposition of the lens cytoplasm with cooling. Intensity auto-correlation functions of the lens protein content are analyzed with the aid of two methods providing information on the populations and dynamics of the scattering elements associated with cold cataract. It is found that the temperature dependence of many measurable parameters changes appreciably at the characteristic temperature ~16+1 oC which is associated with the onset of cold cataract. Extending the temperature range of this work to previously inaccessible regimes, i.e. well below the phase separation or coexistence curve at Tcc, we have been able to accurately determine the temperature dependence of the collective and self-diffusion coefficient of proteins near the spinodal. The analysis showed that the dynamics of proteins bears some resemblance to the dynamics of structural glasses where the apparent activation energy for particle diffusion increases below Tcc indicating a highly cooperative motion. Application of ideas developed for studying the critical dynamics of binary protein/solvent mixtures, as well as the use of a modified Arrhenius equation, enabled us to estimate the spinodal temperature Tsp of the lens nucleus. The applicability of dynamic light scattering as a non-invasive, early-diagnostic tool for ocular diseases is also demonstrated in the light of the findings of the present paper

Taxane induced cystoid macular edema: Case report and integrated pathogenic theory

Purpose: To report a case of a 73-year-old man who presented with decreased visual acuity due to bilateral macular edema after paclitaxel administration for prostate cancer. Methods: The ophthalmic evaluation consisted of medical and ocular history, Best Corrected Visual Acuity, slit-lamp biomicroscopy and Spectral-domain optical coherence tomography / Fluorescein Angiography. Results: Optical Coherence Tomography and Fluorescein Angiography revealed silent cystoid macular edema. After consulting with the oncologist, the cessation of paclitaxel therapy was decided. The patient presented a gradual but steady resumption of the retinal edema, with complete restoration of normal retinal morphology and function within two months. The pathogenesis of the silent Cystoid Macular Edema (CME) is still unclear. Based on our case and a critical review of the previous observations and published data, we propose that the underlying cause of Taxane induced CME is the functional failure of Aquaporin mediated water transport at the level of retinal Intermediate and Deep capillary plexuses, and at lesser extent at the level of the Retinal Pigment Epithelium. Conclusion: Taxane induced silent CME should be attributed to the action of Taxanes on the microtubule guided aquaporin vesicles transport to the cell membrane. In our case of Taxane induced silent CME, withdrawal of the taxane was enough for complete recovery, and no additional treatment was needed. © 2019 Bentham Science Publishers