Endomicroscopic and transcriptomic analysis of impaired barrier function and malabsorption in environmental enteropathy

Introduction: Environmental enteropathy (EE) is associated with growth failure, micronutrient malabsorption and impaired responses to oral vaccines. We set out to define cellular mechanisms of impaired barrier function in EE and explore protective mechanisms. Methods: We studied 49 adults with environmental enteropathy in Lusaka, Zambia using confocal laser endomicroscopy (CLE); histology, immunohistochemistry and mRNA sequencing of small intestinal biopsies; and correlated these with plasma lipopolysaccharide (LPS) and a zinc uptake test. Results: CLE images (median 134 for each study) showed virtually ubiquitous small intestinal damage. Epithelial defects, imaged by histology and claudin 4 immunostaining, were predominantly seen at the tips of villi and corresponded with leakage imaged in vivo by CLE. In multivariate analysis, circulating log-transformed LPS was correlated with cell shedding events (β = 0.83; P = 0.035) and with serum glucagon-like peptide-2 (β = -0.13; P = 0.007). Zinc uptake from a test dose of 25mg was attenuated in 30/47 (64%) individuals and in multivariate analysis was reduced by HIV, but positively correlated with GLP-2 (β = 2.72; P = 0.03). There was a U-shaped relationship between circulating LPS and villus surface area. Transcriptomic analysis identified 23 differentially expressed genes in severe enteropathy, including protective peptides and proteins. Conclusions: Confocal endomicroscopy, claudin 4 immunostaining and histology identify epithelial defects which are probably sites of bacterial translocation, in the presence of which increased epithelial surface area increases the burden of translocation. GLP 2 and other protective peptides may play an important role in mucosal protection in EE

Reversible Disassembly of the Actin Cytoskeleton Improves the Survival Rate and Developmental Competence of Cryopreserved Mouse Oocytes

Effective cryopreservation of oocytes is critically needed in many areas of human reproductive medicine and basic science, such as stem cell research. Currently, oocyte cryopreservation has a low success rate. The goal of this study was to understand the mechanisms associated with oocyte cryopreservation through biophysical means using a mouse model. Specifically, we experimentally investigated the biomechanical properties of the ooplasm prior and after cryopreservation as well as the consequences of reversible dismantling of the F-actin network in mouse oocytes prior to freezing. The study was complemented with the evaluation of post-thaw developmental competence of oocytes after in vitro fertilization. Our results show that the freezing-thawing process markedly alters the physiological viscoelastic properties of the actin cytoskeleton. The reversible depolymerization of the F-actin network prior to freezing preserves normal ooplasm viscoelastic properties, results in high post-thaw survival and significantly improves developmental competence. These findings provide new information on the biophysical characteristics of mammalian oocytes, identify a pathophysiological mechanism underlying cryodamage and suggest a novel cryopreservation method

Iron Behaving Badly: Inappropriate Iron Chelation as a Major Contributor to the Aetiology of Vascular and Other Progressive Inflammatory and Degenerative Diseases

The production of peroxide and superoxide is an inevitable consequence of aerobic metabolism, and while these particular "reactive oxygen species" (ROSs) can exhibit a number of biological effects, they are not of themselves excessively reactive and thus they are not especially damaging at physiological concentrations. However, their reactions with poorly liganded iron species can lead to the catalytic production of the very reactive and dangerous hydroxyl radical, which is exceptionally damaging, and a major cause of chronic inflammation. We review the considerable and wide-ranging evidence for the involvement of this combination of (su)peroxide and poorly liganded iron in a large number of physiological and indeed pathological processes and inflammatory disorders, especially those involving the progressive degradation of cellular and organismal performance. These diseases share a great many similarities and thus might be considered to have a common cause (i.e. iron-catalysed free radical and especially hydroxyl radical generation). The studies reviewed include those focused on a series of cardiovascular, metabolic and neurological diseases, where iron can be found at the sites of plaques and lesions, as well as studies showing the significance of iron to aging and longevity. The effective chelation of iron by natural or synthetic ligands is thus of major physiological (and potentially therapeutic) importance. As systems properties, we need to recognise that physiological observables have multiple molecular causes, and studying them in isolation leads to inconsistent patterns of apparent causality when it is the simultaneous combination of multiple factors that is responsible. This explains, for instance, the decidedly mixed effects of antioxidants that have been observed, etc...Comment: 159 pages, including 9 Figs and 2184 reference

Familial occurrence of pseudoexfoliation in Canada

Background: Genetic factors may play an important role in pseudoexfoliation syndrome. We describe the familial occurrence of pseudoexfoliation in Canadian families.Methods: Probands with pseudoexfoliation were referred to a tertiary care glaucoma service in Ottawa because of a family history of pseudoexfoliation or glaucoma, or both. Probands and family members who agreed to participate underwent a systematic interview and eye examination. The pseudoexfoliation status was classified as affected, suspect or unknown based on preestablished criteria for the diagnosis of pseudoexfoliation and glaucoma.Results: Thirty-four members of 10 families were assessed (18 affected, 2 suspect and 14 status unknown). Six families had two or more generations with pseudoexfoliation, and four families had one generation affected. There was a predominance of females among the affected subjects (17:1), and transmission in all cases appeared to be maternal. Eight of the families were of Irish/Scottish ancestry. Nine (50%) of the affected subjects had cardiovascular disease. Affected subjects tended to be older than suspects and those whose status was unknown (mean age 77, 67 and 55 years respectively). Seven subjects were affected unilaterally and 11 bilaterally. Affected subjects had moderate angle pigmentation in both eyes (mean +2.7, where 0 = no pigment and +4 = dense homogeneous pigment). The mean intraocular pressure in both eyes was higher for the affected subjects (23.1 [standard deviation (SD) 8.6] mm Hg) than for the suspects (16.8 [SD 6.1] mm Hg) and those of unknown status (16.8 [SD 2.9] mm Hg). An enlarged cup:disc ratio was seen in the affected subjects (mean 0.62). Eleven (61%) of the affected subjects had open angles on gonioscopy, and five had occludable angles and required peripheral iridectomy. Ten (56%) of the affected subjects were classified as having glaucoma, and 14 (78%) had evidence of cataract formation in at least one eye.Interpretation: Pseudoexfoliation appears to be transmitted matrilineally, which raises the possibility of mitochondrial inheritance, X-linked inheritance or autosomal inheritance with genomic imprinting. A larger study of families with pseudoexfoliation is necessary to clarify the mode of transmission and to identify the gene(s) involved in the etiology of this disorder