Search

Background: To investigate the relationship between dietary intake of niacin (water‐soluble form of vitamin B3) and retinal nerve fibre layer (RNFL) thickness in healthy eyes. Methods: This cross‐sectional study examined the association between daily niacin intake and RNFL thickness in three large population‐based cohorts with varied age differences. RNFL thickness was extracted from optical coherence tomography data; energy‐adjusted niacin intake was estimated from food frequency questionnaires. Linear mixed‐effects models were utilised to examine the association between RNFL thickness and energy‐adjusted niacin intake. Three separate analyses were conducted, with niacin treated as a continuous, a categorical (quartiles) or a dichotomous (above/below Australian recommended daily intake) variable. Results: In total, 4937 subjects were included in the study [Raine Study Gen2, n = 1204, median age 20; Busselton Healthy Ageing Study (BHAS), n = 1791, median age 64; TwinsUK, n = 1942, median age 64). When analysed as a continuous variable, there was no association between RNFL thickness and niacin intake in any of the three cohorts (95% CI β: Raine Study Gen 2, −0.174 to 0.074; BHAS, −0.066 to 0.078; TwinsUK −0.435 to 0.350). Similar findings were observed with quartiles of niacin intake and for niacin intakes above or below Australian recommended daily intake levels in all three cohorts. Conclusions: Dietary intake of niacin from a standard diet does not appear to be associated with age‐related RNFL thinning in healthy eyes. Supraphysiological doses of niacin may be required for therapeutic effect in the retina. [ABSTRACT FROM AUTHOR]

Aims/Purpose: Glaucoma is an eye disease that is the commonest cause of irreversible blindness worldwide. It has been suggested that gut microbiota can produce reactive oxygen species and pro‐inflammatory cytokines that may travel from the gastric mucosa to distal sites, such as the optic nerve head or trabecular meshwork. There is evidence for a gut‐eye axis, as microbial dysbiosis has been associated with retinal diseases. Here, we investigated the association between glaucoma prevalence and the gut microbiome. Moreover, we analysed the association of the gut microbiome with intraocular pressure (IOP; risk factor of glaucoma) and vertical cup‐to‐disc ratio (VCDR; quantifying glaucoma severity). Methods: The discovery analyses included participants of the Rotterdam Study and the Erasmus Glaucoma Cohort. A total of 225 glaucoma patients were matched on age and sex with 1247 participants without glaucoma. Stool samples were collected and used to generate 16S rRNA gene profiles. We assessed associations with 233 taxa. We used data from the TwinsUK and the Study of Health in Pomerania (SHIP) to replicate our findings. The TwinsUK dataset consisted of 32 participants with glaucoma and 1542 unrelated, unmatched participants without glaucoma. The SHIP dataset consisted of a total of 2546 participants. Results: Several butyrate‐producing taxa (e.g., Butyrivibrio, Caproiciproducens, Clostridium sensu stricto 1, Coprococcus 1, Ruminococcaceae UCG 007, Shuttleworthia) were associated with lower glaucoma prevalence, lower IOP, and smaller VCDR. The replication analyses confirmed the findings from the discovery analyses. Conclusions: Large human studies exploring the link between the gut microbiome and glaucoma are lacking. Our results support the hypothesis that microbial dysbiosis plays a role in the pathophysiology of glaucoma. This research may support future research into the mediating role of butyrate‐producing taxa in the relation between dietary intake and glaucoma. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to assess the feasibility of quantitative ultrasound imaging (QUI) in assessing the biceps brachii muscle and gastrocnemius muscle in adults with multiple sclerosis (MS). Methods: From May to October 2018, we prospectively performed B‐mode ultrasound imaging and ultrasound strain elastography of the biceps brachii muscle and gastrocnemius muscle in 24 patients with MS and 10 age‐matched healthy volunteers. ImageJ (https://imagej.nih.gov/ij) was used to assess the muscle pixel intensity in grayscale images. Using 2‐dimensional speckle‐tracking software, we estimated the muscle axial peak strain (maximum deformation) produced by manual compression with an ultrasound transducer and the muscle longitudinal peak strain (maximum displacement) produced by passive elbow and ankle movements. Muscle QUI parameters used in the study included the mean pixel intensity, axial peak strain ratio (SR = muscle strain/subcutaneous tissue strain), and longitudinal peak SR. Statistical analyses included 1‐way analysis of variance and a post hoc test to examine the differences in QUI parameters among 3 groups (1, affected muscle in patients with MS; 2, unaffected muscle in patients with MS; and 3, healthy muscle in controls) and, in all paired groups, an unpaired t test to compare the muscle SR in patients with MS with a Modified Ashworth Scale (MAS) score of 1 or higher to those with an MAS score of 0. Results: The mean age of the 24 patients with MS was 43 years, and all patients and volunteers were female. We observed a significant difference in QUI parameters among the affected muscle in MS, unaffected muscle in MS, and healthy muscle in all paired groups and in patients with MS between an MAS score of 1 or higher and an MAS score of 0 (all P < .05). Interobserver and intraobserver variability in performing QUI was good (intraclass correlation coefficients >0.75). Conclusions: Our results suggest that QUI is feasible to assess muscle echogenicity and mechanical behaviors in adult MS. [ABSTRACT FROM AUTHOR]

This study investigates a range of commercially available γ-Al2O3 powders by using a combination of integrated experimental techniques. These included general measurements of powder properties by using helium density, BET surface area, and scanning electron microscopy (SEM) analyses. In addition, dynamic light scattering and zeta potential measurements were used to investigate nanoparticle dispersions. Bulk crystal structures were analysed by using comparative X-ray and neutron powder diffraction (XRD and NPD) analyses. Conventional transmission electron microscopy (TEM) was used to determine particle morphology, particle size, composition, and structure. Aberration-corrected TEM was used to investigate the crystallinity of nanoparticles including the existence of any surface reconstruction on commonly observed facetted, cubeoctahedral γ -Al2O3 nanoparticles. From the observation of peak splittings in diffraction data, we favour a description of the γ-Al2O3 structure based on a distortion of the conventionally accepted face-centred cubic ( Fd $\bar 3$ m) structure into a tetragonal I41/ amd structure. Distinct differences between TEM, XRD, and NPD data indicate the presence of some cation disorder within a rigid close-packed oxygen framework. The Rietveld refinement of the NPD data suggests a high level of microstrain of 1.2 %. An improvement to the model is achieved by reducing the aluminium content in the unit cell, which is commensurate with the migration of aluminium ions to the surface and some degree of nonstoichiometry in the particle core. Aberration-corrected TEM imaging and exit wave reconstruction confirm previous evidence for the presence of enhanced surface contrast at {1 1 1} surface facets, which we associate with the presence of excess cation termination. In addition, these {1 1 1} facets are observed to be heavily stepped. These results may have important implications for the thermal stability of metal catalyst nanoparticles on these high-surface area supports; the migration of aluminium ions to the surface provides clear evidence of why these materials perform so well as catalyst supports. [ABSTRACT FROM AUTHOR]

Objectives.—To determine the relationship between levels of ouabain-like compounds (OLC) in the cerebrospinal fluid (CSF) and the occurence of idiopathic intracranial hypertension (IIH). Background.—OLC are naturally occurring inhibitors of the sodium-potassium ATPase that are found in the CSF of mammals. Since the production of CSF is dependent upon sodium-potassium ATPase activity, and since there is evidence that the increased intracranial pressure found in the condition of IIH may be the result of increased CSF production, we hypothesized that the level of endogenous OLC would be reduced in the CSF of patients with IIH. Methods.—CSF samples were obtained from n = 7 patients with IIH and n = 31 patients with neurological disorders other than IIH (“control” patients) who had lumbar puncture as part of their routine evaluation or treatment. The concentration of OLC in the CSF samples was measured using an established ELISA. Results.—Patients with IIH exhibited a concentration of OLC in the CSF of 0.11 ± 0.03 ng/mL. In comparison, the concentration of OLC in CSF samples from non-IIH control patients was 0.12 ± 0.01 ng/mL. These values were not statistically different when compared with a t-test ( P= 0.31). However, the concentration of OLC did negatively correlate to the opening pressure on lumbar puncture, but only in the IIH group ( r=−0.80, P= .03). Furthermore, IIH patients who were newly diagnosed or who were unsuccessfully treated (n = 5 of 7 IIH patients) exhibited OLC concentrations of 0.06 ± 0.1 ng/mL, which is nearly lower than that of the control group ( P= .06). Conclusions.—The average concentration of OLC in IIH patients (treated and untreated) is unlikely to be distinguishable from that in non-IIH control patients with other neurological conditions. However, the concentration of OLC may be inversely related to the intracranial pressure in patients with IIH, and it may prove to be lower in the subgroup of untreated and unsuccessfully treated IIH patients. [ABSTRACT FROM AUTHOR]

Few environmental risk factors are known for glaucoma, in contrast to other common age‐related eye diseases such as AMD and cataract. With the advent of genome‐wide association studies (GWAS), we are increasingly understanding the importance of genetic factors influencing risk of glaucoma. This presentation will discuss results from the largest GWAS of intraocular pressure from the UK Biobank study of over 100 000 people, showing that ~700 common genetic risk variants can predict risk of glaucoma, with an AUC (area under the curve) for high‐tension glaucoma of 0.75 and for normal tension glaucoma of 0.70. Pharmacogenomics is an increasingly important arena, and I will present novel work in large population‐based studies exploring the prediction of response to prostaglandin agonists using genetics. The International Glaucoma Genetics Consortium GWAS of over 30 000 people with glaucoma and 300,000 controls is currently being analysed and preliminary results will be discussed. [ABSTRACT FROM AUTHOR]