PurposeTo compare the retinal nerve fiber layer (RNFL) as well as the macula volume and thickness in the eyes of age-matched healthy controls with no cognitive disabilities with those of elderly people with mild cognitive impairment (MCI) or Alzheimer disease (AD). We used optical coherence tomography (OCT) to determine the effectiveness of the above quantities for early diagnosis of MCI or AD.MethodsNinety eyes were considered in this study, split between 30 normal eyes, 30 eyes from patients with MCI, and 30eyes from patients with AD. All subjects underwent ophthalmologic and cognitive examinations, and measurements of the RNFL thickness as well as macular volume and thickness were taken for all patients using OCT.ResultsThe mean RNFL thickness upon OCT was significantly thinner in the AD group than in the MCI group (p = 0.01). The RNFL was thinner in the superior quadrant in patients with AD when compared to the healthy controls (p = 0.03). The RNFL thicknesses in the inferior, nasal, and temporal quadrants did not differ significantly between the groups. Measurements in the 12 clock-hour zones revealed that zone 11 had a significantly thinner RNFL in the AD group as compared with the healthy control group (p = 0.02). In zone 2, the MCI group had a significantly thinner RNFL than the AD group (p = 0.03).ConclusionsOur OCT findings revealed a neuroanatomic difference in the RNFL thickness among the three groups, i.e., the AD, MCI, and healthy control groups. This suggests that a change in average RNFL thickness could be a meaningful index for diagnosing early AD.

Despite the efforts of the past decade, the origin of the bimodal horizontalbranch (HB) found in some globular clusters (GCs) remains a conundrum. Inspired by the discovery of multiple stellar populations in the most massive Galactic GC, ω Centauri, we investigate the possibility that two distinct populations may coexist and are responsible for the bimodal HBs in the third and fifth brightest GCs, NGC 6388 and NGC 6441. Using the population synthesis technique, we examine two different chemical "self-enrichment" hypotheses in which a primordial GC was sufficiently massive to contain two or more distinct populations as suggested by the populations found in ω Cen: (1) the age-metallicity relation scenario in which two populations with different metallicity and age coexist, following an internal age-metallicity relation, and (2) the super-helium-rich scenario in which GCs contain a certain fraction of helium-enhanced stars, for instance, the second generation stars formed from the helium-enriched ejecta of the first. The comparative study indicates that the detailed color-magnitude diagram morphologies and the properties of the RR Lyrae variables in NGC 6388 and NGC 6441 support the latter scenario; i.e., the model which assumes a minor fraction (∼ 15 %) of helium-excess (Y ≃ 0.3) stars. The results suggest that helium content is the main driver behind the HB bimodality found most often in massive GCs. If confirmed, the GC-to-GC variation of helium abundance should be considered a local effect, further supporting the argument that age is the global second parameter of HB morphology.Recent studies suggest that the long-standing puzzle of the HB bimodality may no longer be a complete mystery. It has been discovered that at least four discrete populations coexist in the most massive Galactic GC, ω Cen (Lee et al. 1999b; Standford et al. 2006, and references therein). This finding obviously opposes the conventional "single-population" picture of GCs, and also provides an instructive precedent for the bimodal-HB feature in other GCs. The multiple populations in ω Cen imply an internal age-metallicity relation (AMR), in that stars having a higher metallicity are younger. Furthermore, subsequent

Organophosphorus (OP) insecticides were among the first pesticides that EPA reevaluated as part of the Food Quality Protection Act of 1996. Our goal was to assess exposure to OP insecticides in the U.S. general population over a six-year period. We analyzed 7,456 urine samples collected as part of three two-year cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999–2004. We measured six dialkylphosphate metabolites of OP pesticides to assess OP pesticide exposure. In NHANES 2003–2004, dimethylthiophosphate was detected most frequently with median and 95th percentile concentrations of 2.03 and 35.3 μg/L, respectively. Adolescents were two to three times more likely to have diethylphosphate concentrations above the 95th percentile estimate of 15.5 μg/L than adults and senior adults. Conversely, for dimethyldithiophosphate, senior adults were 3.8 times and 1.8 times more likely to be above the 95th percentile than adults and adolescents, respectively, while adults were 2.1 times more likely to be above the 95th percentile than the adolescents. Our data indicate that the most vulnerable segments of our population—children and older adults—have higher exposures to OP pesticides than other population segments. However, according to DAP urinary metabolite data, exposures to OP pesticides have declined during the last six years at both the median and 95th percentile levels.