24 research outputs found
Chiasma
Newspaper reporting on events at the Boston University School of Medicine in the 1960s
Classification of Singular Fibres on Rational Elliptic Surfaces in Characteristic Three
We determine and list all possible configurations of singular fibres on
rational elliptic surfaces in characteristic three. In total, we find that 267
distinct configurations exist. This result complements Miranda and Persson's
classification in characteristic zero, and Lang's classification in
characteristic two.Comment: 40 Pages. Minor typos correcte
Recommended from our members
In vivo induction of membrane damage by β-amyloid peptide oligomers.
Exposure to the β-amyloid peptide (Aβ) is toxic to neurons and other cell types, but the mechanism(s) involved are still unresolved. Synthetic Aβ oligomers can induce ion-permeable pores in synthetic membranes, but whether this ability to damage membranes plays a role in the ability of Aβ oligomers to induce tau hyperphosphorylation, or other disease-relevant pathological changes, is unclear. To examine the cellular responses to Aβ exposure independent of possible receptor interactions, we have developed an in vivo C. elegans model that allows us to visualize these cellular responses in living animals. We find that feeding C. elegans E. coli expressing human Aβ induces a membrane repair response similar to that induced by exposure to the CRY5B, a known pore-forming toxin produced by B. thuringensis. This repair response does not occur when C. elegans is exposed to an Aβ Gly37Leu variant, which we have previously shown to be incapable of inducing tau phosphorylation in hippocampal neurons. The repair response is also blocked by loss of calpain function, and is altered by loss-of-function mutations in the C. elegans orthologs of BIN1 and PICALM, well-established risk genes for late onset Alzheimer's disease. To investigate the role of membrane repair on tau phosphorylation directly, we exposed hippocampal neurons to streptolysin O (SLO), a pore-forming toxin that induces a well-characterized membrane repair response. We find that SLO induces tau hyperphosphorylation, which is blocked by calpain inhibition. Finally, we use a novel biarsenical dye-tagging approach to show that the Gly37Leu substitution interferes with Aβ multimerization and thus the formation of potentially pore-forming oligomers. We propose that Aβ-induced tau hyperphosphorylation may be a downstream consequence of induction of a membrane repair process
The Globular Cluster/Central Black Hole Connection in Galaxies
We explore the relation between the total globular cluster population in a
galaxy (N_GC) and the the mass of its central black hole (M_BH). Using a sample
of 33 galaxies, twice as large as the original sample discussed by Burkert &
Tremaine (2010), we find that N_GC for elliptical and spiral galaxies increases
in almost precisely direct proportion to M_BH. The S0-type galaxies by contrast
do not follow a clear trend, showing large scatter in M_BH at a given N_GC.
After accounting for observational measurement uncertainty, we find that the
mean relation defined by the E and S galaxies must also have an intrinsic or
"cosmic" scatter of +-0.2 in either logN_GC or logM_BH. The residuals from this
correlation show no trend with globular cluster specific frequency. We suggest
that these two types of galaxy subsystems (central black hole and globular
cluster system) may be closely correlated because they both originated at high
redshift during the main epoch of hierarchical merging, and both require
extremely high-density conditions for formation. Lastly, we note that roughly
10% of the galaxies in our sample (one E, one S, and two S0) deviate strongly
from the main trend, all in the sense that their M_BH is at least 10x smaller
than would be predicted by the mean relation.Comment: 7 pages, 4 figures; accepted for publication in MNRA
The genetic architecture of the human cerebral cortex
The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder
Prevalence of Hypertension and Associated Risk Factors in Western Alaska Native People: The Western Alaska Tribal Collaborative for Health (WATCH) Study.
Hypertension is a common chronic disease and a key risk factor in the development of cardiovascular disease. The Western Alaska Tribal Collaborative for Health study consolidates baseline data from four major cohorts residing in the Norton Sound and Yukon-Kuskokwim regions of western Alaska. This consolidated cohort affords an opportunity for a systematic analysis of high blood pressure and its correlates in a unique population with high stroke rates over a wide age range. While the prevalence of hypertension among western Alaska Native people (30%, age-standardized) is slightly less than that of the US general population (33%), cardiovascular disease is a leading cause of mortality in this rural population. The authors found that improvement is needed in hypertension awareness as about two thirds (64%) of patients reported awareness and only 39% with hypertension were controlled on medication. Future analyses assessing risk and protective factors for incident hypertension in this population are indicated