Hearing the Voice of Medical Students Worldwide

The Student Forum, a new section of PLoS Medicine, is a space where medical students from across the world can exchange ideas about the critical issues affecting health and health care from their unique perspectiv

Potential benefit from using an identified major gene in BLUP evaluation with truncation and optimal selection

International audienc

The Role of Education in the Relationship Between Age of Migration to the United States and Risk of Cognitive Impairment Among Older Mexican Americans

Prior research indicates age of migration is associated with cognitive health outcomes among older Mexican Americans; however, factors that explain this relationship are unclear. This study used eight waves from the Hispanic Established Populations for the Epidemiologic Study of the Elderly to examine the role of education in the risk for cognitive impairment (CI) by nativity, age of migration, and gender. Foreign-born women had a higher risk for CI than U.S.-born women, regardless of age of migration. After adjusting for education, this risk remained significant only for late-life migrant women (risk ratio [RR] = 1.28). Foreign-born men who migrated at \u3e50 had significantly higher risk for CI compared to U.S.-born men (RR = 1.33) but not significant after adjusting for education. Findings from a decomposition analysis showed education significantly mediated the association between age of migration and CI. This study highlights the importance of education in explaining the association between age of migration and CI

Sub-chronic inhalation of high concentrations of manganese sulfate induces lower airway pathology in rhesus monkeys

BACKGROUND: Neurotoxicity and pulmonary dysfunction are well-recognized problems associated with prolonged human exposure to high concentrations of airborne manganese. Surprisingly, histological characterization of pulmonary responses induced by manganese remains incomplete. The primary objective of this study was to characterize histologic changes in the monkey respiratory tract following manganese inhalation. METHODS: Subchronic (6 hr/day, 5 days/week) inhalation exposure of young male rhesus monkeys to manganese sulfate was performed. One cohort of monkeys (n = 4–6 animals/exposure concentration) was exposed to air or manganese sulfate at 0.06, 0.3, or 1.5 mg Mn/m(3 )for 65 exposure days. Another eight monkeys were exposed to manganese sulfate at 1.5 mg Mn/m(3 )for 65 exposure days and held for 45 or 90 days before evaluation. A second cohort (n = 4 monkeys per time point) was exposed to manganese sulfate at 1.5 mg Mn/m(3 )and evaluated after 15 or 33 exposure days. Evaluations included measurement of lung manganese concentrations and evaluation of respiratory histologic changes. Tissue manganese concentrations were compared for the exposure and control groups by tests for homogeneity of variance, analysis of variance, followed by Dunnett's multiple comparison. Histopathological findings were evaluated using a Pearson's Chi-Square test. RESULTS: Animals exposed to manganese sulfate at ≥0.3 mg Mn/m(3 )for 65 days had increased lung manganese concentrations. Exposure to manganese sulfate at 1.5 mg Mn/m(3 )for ≥15 exposure days resulted in increased lung manganese concentrations, mild subacute bronchiolitis, alveolar duct inflammation, and proliferation of bronchus-associated lymphoid tissue. Bronchiolitis and alveolar duct inflammatory changes were absent 45 days post-exposure, suggesting that these lesions are reversible upon cessation of subchronic high-dose manganese exposure. CONCLUSION: High-dose subchronic manganese sulfate inhalation is associated with increased lung manganese concentrations and small airway inflammatory changes in the absence of observable clinical signs. Subchronic exposure to manganese sulfate at exposure concentrations (≤0.3 mg Mn/m(3)) similar to the current 8-hr occupational threshold limit value established for inhaled manganese was not associated with pulmonary pathology

Nanowire electron scattering spectroscopy

Methods and devices for spectroscopic identification of molecules using nanoscale wires are disclosed. According to one of the methods, nanoscale wires are provided, electrons are injected into the nanoscale wire; and inelastic electron scattering is measured via excitation of low-lying vibrational energy levels of molecules bound to the nanoscale wire

Effect of Aging on the Reversibility of Pu(IV) Sorption to Goethite

Designing safe remediation and disposal strategies for plutonium (Pu) requires understanding the sorption affinity of Pu for soil minerals. Sorption of Pu(IV) was examined with respect to aging for a goethite system using batch sorption experiments. Sorption of Pu(IV) to iron oxides has been observed to be strong, rapid, and possibly irreversible or hysteretic. These observations may be explained by aging, a surface chemical process happening after initial sorption which causes a change in contaminant surface speciation over time. Measurements of Pu(IV) sorption are often complicated by oxidative leaching of Pu(IV) as Pu(V). Desferrioxamine B (DFOB) is a complexant capable of competing with the proposed strong surface complexes. Additionally, DFOB minimizes oxidative leaching by forming strong Pu(IV)-DFOB complexes, thereby stabilizing Pu(IV) as the dominant aqueous oxidation state. Pu(IV) was reacted in suspensions of 0.1g/L goethite and 10mM NaCl spanning pH 4–7 for various lengths of time (1,6,15,34 and 116 days). Supernatant was replaced with a 1.7µM DFOB solution and, after 34 more days, analyzed for aqueous Pu by liquid scintillation counting. Modeling sorption curves in FITEQL yielded logK values which increased from 0.078 to 0.953 over 116 days, indicating Pu(IV) sorption onto goethite becomes less reversible with aging

In vivo development of dendritic orientation in wild-type and mislocalized retinal ganglion cells

<p>Abstract</p> <p>Background</p> <p>Many neurons in the central nervous system, including retinal ganglion cells (RGCs), possess asymmetric dendritic arbors oriented toward their presynaptic partners. How such dendritic arbors become biased during development <it>in vivo </it>is not well understood. Dendritic arbors may become oriented by directed outgrowth or by reorganization of an initially unbiased arbor. To distinguish between these possibilities, we imaged the dynamic behavior of zebrafish RGC dendrites during development <it>in vivo</it>. We then addressed how cell positioning within the retina, altered in <it>heart-and-soul </it>(<it>has</it>) mutants, affects RGC dendritic orientation.</p> <p>Results</p> <p><it>In vivo </it>multiphoton time-lapse analysis revealed that RGC dendrites initially exhibit exploratory behavior in multiple directions but progressively become apically oriented. The lifetimes of basal and apical dendrites were generally comparable before and during the period when arbors became biased. However, with maturation, the addition and extension rates of basal dendrites were slower than those of the apical dendrites. Oriented dendritic arbors were also found in misplaced RGCs of the <it>has </it>retina but there was no preferred orientation amongst the population. However, <it>has </it>RGCs always projected dendrites toward nearby neuropil where amacrine and bipolar cell neurites also terminated. Chimera analysis showed that the abnormal dendritic organization of RGCs in the mutant was non-cell autonomous.</p> <p>Conclusions</p> <p>Our observations show that RGC dendritic arbors acquire an apical orientation by selective and gradual restriction of dendrite addition to the apical side of the cell body, rather than by preferential dendrite stabilization or elimination. A biased arbor emerges at a stage when many of the dendritic processes still appear exploratory. The generation of an oriented RGC dendritic arbor is likely to be determined by cell-extrinsic cues. Such cues are unlikely to be localized to the basal lamina of the inner retina, but rather may be provided by cells presynaptic to the RGCs.</p