The effect of SH3 domains on dynamin activity and oligomerisation

Dynamin is a GTPase enzyme that mediates vesicle fission during endocytosis to release new vesicles into the cell cytoplasm. It is recruited to sites of endocytosis in cells where it promotes vesicle fission by assembling into a collar around the vesicle neck. Dynamin is regulated by binding to proteins containing src homology 3 (SH3) domain, which stimulate its oligomerisation into rings with an associated increase in dynamin GTPase activity. However, each SH3 domain has been inconsistently studied in isolation from the others and sometimes as part of the full-length protein. This study revealed important new insights into dynamin modulation, isoform functional diversity and therefore potential function in endocytosis. Through a systematic approach, the observations overturn conclusions of several previous studies and reveal many new insights into dynamin activation and the remarkable diversity in the way SH3 domains stimulate dynamin. The existence of a previously unknown assembly independent allosteric mechanism to stimulate dynamin GTPase is revealed. The work highlights the SH3 domain of SNX9 as the most potent and consistent in vitro regulator of dynamin oligomerisation and activity. It also mapped the unique binding mechanism for SNX9 on dynamin I and revealed that this interaction is potentially phospho-regulated

Resummations of free energy at high temperature

We discuss resummation strategies for free energy in quantum field theories at nonzero temperatures T. We point out that resummations should be performed for the short- and long-distance parts separately in order to avoid spurious interference effects and double-counting. We then discuss and perform Pade resummations of these two parts for QCD at high T. The resummed results are almost invariant under variation of the renormalization and factorization scales. We perform the analysis also in the case of the massless scalar $\phi^4$ theory.Comment: 16 pages, revtex4, 15 eps-figures; minor typographic errors corrected; the version as it appears in Phys.Rev.

Understanding How Inequality in the Distribution of Income Affects Health

Research on the determinants of health has almost exclusively focused on the individual but it seems clear we cannot understand or improve patterns of population health without engaging structural determinants at the societal level. This article traces the development of research on income distribution and health to the most recent epidemiologic studies from the USA that show how income inequality is related to age-adjusted mortality within the 50 States. (r 520.62, p 5 0.0001) even after accounting for absolute levels of income. We discuss potential material, psychological, social and behavioral pathways through which income distribution might be linked to health status. Distributional aspects of the economy are important determinants of health and may well provide one of the most pertinent indicators of overall social well-being.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66686/2/10.1177_135910539700200303.pd

Study of ttbar Production in ppbar Collisions Using Total Transverse Energy

We analyze a sample of W + jet events collected with the Collider Detector at Fermilab (CDF) in ppbar collisions at sqrt(s) = 1.8 TeV to study ttbar production. We employ a simple kinematical variable "H", defined as the scalar sum of the transverse energies of the lepton, neutrino and jets. For events with a W boson and four or more jets, the shape of the "H" distribution deviates by 3.8 standard deviations from that expected from known backgrounds to ttbar production. However this distribution agrees well with a linear combination of background and ttbar events, the agreement being best for a top mass of 180 GeV/c^2.Comment: Postscript file (gzip+uuencode). 5-page, two-column PRL format (RevTex). Submitted to Phys. Rev. Lett. 09 June 199