Association of serum lipid levels with retinal hard exudate area in African Americans with type 2 diabetes.

PURPOSE: Previous studies have yielded conflicting results regarding whether serum lipid levels are associated with retinal hard exudates in diabetic retinopathy. The majority of studies have assessed hard exudates only as a dichotomous trait (presence vs. absence) and included limited numbers of African Americans (AA). The purpose of this study was to determine if there are any associations between serum lipid levels and hard exudates in AA with type 2 diabetes (T2D). METHODS: 890 AA participants with T2D were enrolled from 5 sites. Macular fundus photographs were graded by masked ophthalmologist investigators. Hard exudate areas were measured using a semi-automated algorithm and ImageJ software. Multivariate regression models were used to determine the association between serum lipid levels and (1) presence of hard exudate and (2) area of hard exudate. RESULTS: Presence of hard exudates was associated with higher total cholesterol [(odds ratio (OR) = 1.08, 95 % confidence interval (CI) 1.03-1.13, P = 0.001)] and higher low-density lipoprotein (LDL) cholesterol (OR = 1.08, 95 % CI 1.03-1.14, P = 0.005) in models controlling for other risk factors. Hard exudate area was also associated with both higher total and LDL cholesterol levels (P = 0.04 and 0.01, respectively) in multivariate models controlling for other risk factors. CONCLUSIONS: Higher total and LDL cholesterol were associated with the presence of hard exudates and a greater hard exudate area in AA with T2D. This information can be used to counsel diabetic patients regarding the importance of lipid control to decrease the risk of macular hard exudates.

Fourth class of convex equilateral polyhedron with polyhedral symmetry related to fullerenes and viruses.

The three known classes of convex polyhedron with equal edge lengths and polyhedral symmetry--tetrahedral, octahedral, and icosahedral--are the 5 Platonic polyhedra, the 13 Archimedean polyhedra--including the truncated icosahedron or soccer ball--and the 2 rhombic polyhedra reported by Johannes Kepler in 1611. (Some carbon fullerenes, inorganic cages, icosahedral viruses, geodesic structures, and protein complexes resemble these fundamental shapes.) Here we add a fourth class, "Goldberg polyhedra," which are also convex and equilateral. We begin by decorating each of the triangular facets of a tetrahedron, an octahedron, or an icosahedron with the T vertices and connecting edges of a "Goldberg triangle." We obtain the unique set of internal angles in each planar face of each polyhedron by solving a system of n equations and n variables, where the equations set the dihedral angle discrepancy about different types of edge to zero, and the variables are a subset of the internal angles in 6gons. Like the faces in Kepler's rhombic polyhedra, the 6gon faces in Goldberg polyhedra are equilateral and planar but not equiangular. We show that there is just a single tetrahedral Goldberg polyhedron, a single octahedral one, and a systematic, countable infinity of icosahedral ones, one for each Goldberg triangle. Unlike carbon fullerenes and faceted viruses, the icosahedral Goldberg polyhedra are nearly spherical. The reasoning and techniques presented here will enable discovery of still more classes of convex equilateral polyhedra with polyhedral symmetry.

OPTICAL COHERENCE TOMOGRAPHY CHARACTERISTICS OF MACULAR EDEMA AND HARD EXUDATES AND THEIR ASSOCIATION WITH LIPID SERUM LEVELS IN TYPE 2 DIABETES.

PURPOSE: To determine whether hyperreflective foci (HF) and macular thickness on spectral domain ocular coherence tomography are associated with lipid levels in patients with Type 2 diabetes. METHODS: Two hundred and thirty-eight participants from four sites had fundus photographs and spectral domain ocular coherence tomography images graded for hard exudates and HF, respectively. Regression models were used to determine the association between serum lipid levels and 1) presence of HF and hard exudates and 2) central subfield macular thickness, central subfield macular volume, and total macular volume. RESULTS: All patients with hard exudates on fundus photographs had corresponding HF on spectral domain ocular coherence tomography, but 57% of patients with HF on optical coherence tomography did not have hard exudates detected in their fundus photographs. Presence of HF was associated with higher total cholesterol (odds ratio = 1.13, 95% confidence interval = 1.01-1.27, P = 0.03) and higher low-density lipoprotein levels (odds ratio = 1.17, 95% confidence interval = 1.02-1.35, P = 0.02) in models adjusting for other risk factors. The total macular volume was also associated with higher total cholesterol (P = 0.009) and triglyceride (P = 0.02) levels after adjusting for other risk factors. CONCLUSION: Higher total and low-density lipoprotein cholesterol were associated with presence of HF on spectral domain ocular coherence tomography. Total macular volume was associated with higher total cholesterol and triglyceride levels.

Risk Factors for Proliferative Diabetic Retinopathy in African Americans with Type 2 Diabetes.

PURPOSE: To assess personal and demographic risk factors for proliferative diabetic retinopathy in African Americans with type 2 diabetes. METHODS: In this prospective, non-interventional, cross-sectional case-control study, 380 African Americans with type 2 diabetes were enrolled. Participants were recruited prospectively and had to have either: (1) absence of diabetic retinopathy after ≥10 years of type 2 diabetes, or (2) presence of proliferative diabetic retinopathy when enrolled. Dilated, 7-field fundus photographs were graded using the Early Treatment Diabetic Retinopathy Study scale. Covariates including hemoglobin A1C (HbA1C), blood pressure, height, weight and waist circumference were collected prospectively. Multivariate regression models adjusted for age, sex and site were constructed to assess associations between risk factors and proliferative diabetic retinopathy. RESULTS: Proliferative diabetic retinopathy was associated with longer duration of diabetes (odds ratio, OR, 1.62, p < 0.001), higher systolic blood pressure (OR 1.65, p < 0.001) and insulin use (OR 6.65, p < 0.001) in the multivariate regression analysis. HbA1C was associated with proliferative diabetic retinopathy in the univariate analysis (OR 1.31, p = 0.002) but was no longer significant in the multivariate analysis. CONCLUSIONS: In this case-control study of African Americans with type 2 diabetes, duration of diabetes, systolic hypertension and insulin use were strong risk factors for the development of proliferative diabetic retinopathy. Interestingly, HbA1C did not confer additional risk in this cohort.

African Ancestry Analysis and Admixture Genetic Mapping for Proliferative Diabetic Retinopathy in African Americans.

PURPOSE: To examine the relationship between proportion of African ancestry (PAA) and proliferative diabetic retinopathy (PDR) and to identify genetic loci associated with PDR using admixture mapping in African Americans with type 2 diabetes (T2D). METHODS: Between 1993 and 2013, 1440 participants enrolled in four different studies had fundus photographs graded using the Early Treatment Diabetic Retinopathy Study scale. Cases (n = 305) had PDR while controls (n = 1135) had nonproliferative diabetic retinopathy (DR) or no DR. Covariates included diabetes duration, hemoglobin A1C, systolic blood pressure, income, and education. Genotyping was performed on the Affymetrix platform. The association between PAA and PDR was evaluated using logistic regression. Genome-wide admixture scanning was performed using ANCESTRYMAP software. RESULTS: In the univariate analysis, PDR was associated with increased PAA (odds ratio [OR] = 1.36, 95% confidence interval [CI] = 1.16-1.59, P = 0.0002). In multivariate regression adjusting for traditional DR risk factors, income and education, the association between PAA and PDR was attenuated and no longer significant (OR = 1.21, 95% CI = 0.59-2.47, P = 0.61). For the admixture analyses, the maximum genome-wide score was 1.44 on chromosome 1. CONCLUSIONS: In this largest study of PDR in African Americans with T2D to date, an association between PAA and PDR is not present after adjustment for clinical, demographic, and socioeconomic factors. No genome-wide significant locus (defined as having a locus-genome statistic > 5) was identified with admixture analysis. Further analyses with even larger sample sizes are needed to definitively assess if any admixture signal for DR is present.

The structure of reef fish metapopulations: modelling larval dispersal and retention patterns.

An improved understanding of the dispersal patterns of marine organisms is a prerequisite for successful marine resource management. For species with dispersing larvae, regional-scale hydrodynamic models provide a means of obtaining results over relevant spatial and temporal scales. In an effort to better understand the role of the physical environment in dispersal, we simulated the transport of reef fish larvae among 321 reefs in and around the Cairns Section of the Great Barrier Reef Marine Park over a period of 20 years. Based on regional-scale hydrodynamics, our models predict the spatial and temporal frequency of significant self-recruitment of the larvae of certain species. Furthermore, the results suggest the importance of a select few local populations in ensuring the persistence of reef fish metapopulations over regional scales.

Pneumobilia: a case report and literature review on its surgical approaches.

Gallstones ileus is an uncommon cause but important cause of small bowel obstruction. The gallstone enters the intestinal lumen via a fistula located in the duodenum (cholecystoduodenal), or rarely, in the colon (cholecystocolonic) or stomach (cholecystogastric). This may result in large bowel or gastric outlet obstruction (Bouveret's Syndrome). Gallstone ileus affects the elderly females pre-dominantly and is associated with a high morbidity and mortality rate if diagnosis and urgent surgical intervention are delayed. In this paper, we report on the case of an elderly lady who presented with classical symptoms and signs of small bowel obstruction. She was subsequently diagnosed with gallstone ileus due to a large gallstones lodged in the intestinal lumen. We perform a literature review on this rare disease and discuss the two main surgical approaches in managing this condition. Gallstone ileus should be considered in the differential diagnosis of small bowel obstruction especially in elderly women who have no history of abdominal surgery or abdominal hernia. Early intervention is important because of the high mortality rate due to the poor general condition that often exists in this subgroup of patients. There is no general consensus on gold standard surgical approach in these cases but a two-stage procedure (either enterotomy alone or enterotomy and subsequent cholecystectomy) has been shown to be associated with lower mortality rates.