Cognitive deficits in aged rats correlate with levels of L-arginine, not with nNOS expression or 3,4-DAP-evoked transmitter release in the frontoparietal cortex.

Aging is associated with altered neurotransmitter function in the brain. In this study, we measured release parameters for acetylcholine (ACh), norepinephrine and serotonin in the frontoparietal cortex of young and aged rats. We also determined cortical amino acid concentrations and nitric oxide (NO) synthase function. Prior to sacrifice, the rats had been tested for Morris water-maze performance. In aged, compared with young rats, we observed a reduction in both uptake of choline and acetylcholine release. Serotonin release and L-arginine concentrations (a precursor of NO) showed an aging-related increase; however, L-citrulline/L-arginine ratios were decreased in aged rats. Moreover, while most age-related changes in transmitter release or neurochemical markers were not related to the learning performance, L-arginine concentrations were positively correlated to cognitive deficits. NO synthase concentrations were not affected by aging. It is suggested that events related to L-arginine-to-L-citrulline/NO metabolism in the frontoparietal cortex may take part in age-related cognitive deficits.     

Tear analysis in ocular surface diseases

The thin layer of tears covering the ocular surface are a complex body fluid containing thousands of molecules of varied form and function of several origins. In this review, we have discussed some key issues in the analysis of tears in the context of understanding and diagnosing eye disease using current technologies of proteomics and metabolomics, and for their potential for clinical application. In the last several years, advances in proteomics/metabolomics/lipidomics technologies have greatly expanded our knowledge of the chemical composition of tear fluid. The quickened pace of studies has shown that tears as a complex extra-cellular fluid of the ocular surface contains a great deal of molecular information useful for the diagnosis, prognosis, and treatment of ocular surface diseases that has the ability to addresses the emphasis on personalized medicine and biomarkers of disease. Future research directions will likely include (1) standardize tear collection, storage, extraction, and sample preparation; (2) quantitative proteomic analysis of tear proteins using multiple reaction monitoring (MRM)-based mass spectrometry; (3) population based studies of human tear proteomics/metabolomics; (4) tear proteomics/metabolomics for systemic diseases; and (5) functional studies of tear proteins.     

Analysis of Meibum and Tear Lipids

The meibum is a lipid-rich secretion that is the primary component of the external layer of the tear film. The meibomian glands produce the meibum, and meibomian gland dysfunction can lead to degradation of the tear film. Such dysfunction can result in ocular irritation, inflammation, and clinical disease. Understanding this relationship is critical to preventing ocular disease; therefore, a search of peer-reviewed literature focusing on the collection, quantification, and analysis of normal and abnormal meibum and tear lipids was conducted. Numerous collection and quantification techniques are described, including their advantages and disadvantages. Studies indicate that the meibum and tear lipids consist of a large array of polar and nonpolar lipids; individual lipids or their classes can be correlated to pathology. Significant amounts of lipids are deposited on contact lenses, depending on the nature of their polymer chemistry. These findings taken together indicate that normal meibum and tear lipids are essential for normal ocular health. Additional studies are required to provide a better understanding of the meibum and tear film biomolecules so that more effective treatments for blepharitis, dry eye disease, and tear film-related contact lens complications can be devised.     

Total ocular, anterior corneal and lenticular higher order aberrations in hyperopic, myopic and emmetropic eyes

Total ocular higher order aberrations and corneal topography of myopic, emmetropic and hyperopic eyes of 675 adolescents (16.9 ± 0.7 years) were measured after cycloplegia using COAS aberrometer and Medmont videokeratoscope. Corneal higher order aberrations were computed from the corneal topography maps and lenticular (internal) higher order aberrations derived by subtraction of corneal aberrations from total ocular aberrations. Aberrations were measured for a pupil diameter of 5 mm. Multivariate analysis of variance followed by multiple regression analysis found significant difference in the fourth order aberrations (SA RMS, primary spherical aberration coefficient) between the refractive error groups. Hyperopic eyes (+0.083 ± 0.05 μm) had more positive total ocular primary spherical aberration compared to emmetropic (+0.036 ± 0.04 μm) and myopic eyes (low myopia = +0.038 ± 0.05 μm, moderate myopia = +0.026 ± 0.06 μm) (p < 0.05). No difference was observed for the anterior corneal spherical aberration. Significantly less negative lenticular spherical aberration was observed for the hyperopic eyes (−0.038 ± 0.05 μm) than myopic (low myopia = −0.088 ± 0.04 μm, moderate myopia = −0.095 ± 0.05 μm) and emmetropic eyes (−0.081 ± 0.04 μm) (p < 0.05). These findings suggest the existence of differences in the characteristics of the crystalline lens (asphericity, curvature and gradient refractive index) of hyperopic eyes versus other eyes.     

Corrective techniques of lacrimal obstruction in the vertical system

PurposeTo describe current surgical techniques of dacryocystorhinostomy (DCR) and to compare their effectiveness by analysing the advantages and disadvantages between external, endonasal and transcanalicular surgery.Patients and methodsA total of 91 DCRs were analysed using a retrospective, cross-sectional and multicentre study in 75 patients who had symptoms of nasolacrimal duct obstruction. Of these, 28 were operated using external DCR, 31 endonasal technic, and 32 transcanalicular DCR with diode laser. Outcomes were evaluated subjectively using patient symptoms for the grade of epiphora and the results from the syringing before and after surgery.ResultsExternal DCR was performed in 28 cases, with 19 cases asymptomatic (67.85%), and 20 patients had a patent tract (71.42%). Endonasal DCR was performed in 31 cases, of which 19 cases were asymptomatic (61.29%), and 21 showed patency of the nasolacrimal duct (67.74%). A transcanalicular technique was performed in 32 cases, with absence of epiphora in 24 patients (75%), and the syringing was successful in 24 of them (75%).ConclusionsAny of these 3 surgery techniques would be an adequate treatment for lacrimal obstruction, due to the significant development of endonasal and transcanalicular techniques in recent decades. With improvement, we could use either endonasal or transcanalicular techniques with diode laser with the same lever of effectiveness as the classic external approach, with the advantages of minimally invasive surgery.     

Design and conduct of clinical trials: report of the Clinical Trials Subcommittee of the International Dry Eye WorkShop (2007)

This report summarizes some universal concepts with regard to clinical trials in general and other issues pertaining to clinical trials specifically tailored to the study of therapeutic intervention in dry eye disease. The report also makes recommendations for logistical design and implementation of such trials. It identifies peculiarities of dry eye disease that complicate clinical trial design, such as the lack of correlation of signs and symptoms, as well as the likelihood of control interventions having a lubricant (placebo) effect. Strategies for environmental trials and controlled adverse environment trials are reviewed.