Infection frequently triggers thrombotic microangiopathy in patients with preexisting risk factors : a single-institution experience

Thrombotic microangiopathies are rare conditions characterized by microangiopathic hemolytic anemia, microthrombi, and multiorgan insult. The disorders, which include hemolytic uremic syndrome and thrombotic thrombocytopenic purpura, are often acute and life threatening. We report a retrospective analysis of 65 patients presenting to our institution from 1997 to 2008 with all forms of thrombotic microangiopathy. Therapeutic plasma exchange was a requirement for analysis and 65 patients were referred to our institution; 66% of patients were female and median age at presentation was 52 years. Bacterial infection was the most commonly identified etiologic factor and in the multivariate model was the only significant variable associated with survival outcome (odds ratio 5.1, 95% confidence interval, 1.2-21.7). As infection can be considered a common trigger event for thrombotic microangiopathy, patients with hepatobiliary sepsis may benefit from elective cholecystectomy. We conclude that bacterial infection frequently triggers TTP and other thrombotic microangiopathies in patients with preexisting risk factors and propose a model for the development of these syndromes

Security of Tenure and Land Registration in Africa: Literature Review and Synthesis

In 1984, the Land Tenure Center embarked on a project to evaluate the experiences with land registration and tenure reform in Africa. The goal was to determine is African states been able to use tenure reform and land registration to provide greater security of tenure than was available through customary tenure systems. Donor agencies focused attention on the creation of individual freehold title, emphasizing the heightened security of holding, marketability, and access to credit under such tenure. National governments, on the other hand, were more concerned to see that land was used productively rather than merely accumulated for purposes of prestige or inheritance or as a hedge against inflation, and for this reason have tended to favor granting more circumscribed rights, such as leaseholds or rights of occupancy. This literature review and synthesis was prepared as part of an effort to increase very substantially our knowledge, especially on a quantitative level, of tenure and development relationships in Africa. The literature review is an attempt to gather in one place data about the diverse efforts at land registration and to describe briefly for each country the various registration programs that have taken place (if any), why they were undertaken, and what subsequent studies of these programs have found. Among other things, it will be seen that the intended benefits, and beneficiaries, of land registration have changed over the century or so since the first systems were put in place. In addition to these variations over time, there are also differences among Anglophone, Francophone, and Lusophone countries, differences that not only influenced the structure of registration systems established during the colonial era, but also continue to inform the kinds of registration systems adopted today.Land Economics/Use,

Combinatorics of Boundaries in String Theory

We investigate the possibility that stringy nonperturbative effects appear as holes in the world-sheet. We focus on the case of Dirichlet string theory, which we argue should be formulated differently than in previous work, and we find that the effects of boundaries are naturally weighted by $e^{-O(1/g_{\rm st})}$.Comment: 12 pages, 2 figures, LaTe

Ubiquitination and proteasomal degradation of ATG12 regulates its proapoptotic activity

During macroautophagy, conjugation of ATG12 to ATG5 is essential for LC3 lipidation and autophagosome formation. Additionally, ATG12 has ATG5-independent functions in diverse processes including mitochondrial fusion and mitochondrial-dependent apoptosis. In this study, we investigated the regulation of free ATG12. In stark contrast to the stable ATG12–ATG5 conjugate, we find that free ATG12 is highly unstable and rapidly degraded in a proteasome-dependent manner. Surprisingly, ATG12, itself a ubiquitin-like protein, is directly ubiquitinated and this promotes its proteasomal degradation. As a functional consequence of its turnover, accumulation of free ATG12 contributes to proteasome inhibitor-mediated apoptosis, a finding that may be clinically important given the use of proteasome inhibitors as anticancer agents. Collectively, our results reveal a novel interconnection between autophagy, proteasome activity, and cell death mediated by the ubiquitin-like properties of ATG12

Remarks on the Classical Size of D-Branes

We discuss different criteria for `classical size' of extremal Dirichlet p-branes in type-II supergravity. Using strong-weak coupling duality, we find that the size of the strong-coupling region at the core of the (p<3)-branes, is always given by the asymptotic string scale, if measured in the weakly coupled dual string metric. We also point out how the eleven-dimensional Planck scale arises in the classical 0-brane solution, as well as the ten-dimensional Planck scale in the D-instanton solution.Comment: 8 pp, harvma

D-Branes on K3-Fibrations

B-type D-branes are constructed on two different K3-fibrations over IP_1 using boundary conformal field theory at the rational Gepner points of these models. The microscopic CFT charges are compared with the Ramond charges of D-branes wrapped on holomorphic cycles of the corresponding Calabi-Yau manifold. We study in particular D4-branes and bundles localized on the K3 fibers, and find from CFT that each irreducible component of a bundle on K3 gains one modulus upon fibration over IP_1. This is in agreement with expectations and so provides a further test of the boundary CFT.Comment: 16p, harvmac, tables.tex; typos corrected, refs added, discussion about moduli spaces improve

A Kaluza-Klein inspired action for chiral p-forms and their anomalies

The dynamics of chiral p-forms can be captured by a lower-dimensional parity-violating action motivated by a Kaluza-Klein reduction on a circle. The massless modes are (p-1)-forms with standard kinetic terms and Chern-Simons couplings to the Kaluza-Klein vector of the background metric. The massive modes are p-forms charged under the Kaluza-Klein vector and admit parity-odd first-order kinetic terms. Gauge invariance is implemented by a Stueckelberg-like mechanism using (p-1)-forms. A Chern-Simons term for the Kaluza-Klein vector is generated at one loop by massive p-form modes. These findings are shown to be consistent with anomalies and supersymmetry for six-dimensional supergravity theories with chiral tensor multiplets.Comment: 4 pages, 1 figur

I-Brane Inflow and Anomalous Couplings on D-Branes

We show that the anomalous couplings of $D$-brane gauge and gravitational fields to Ramond-Ramond tensor potentials can be deduced by a simple anomaly inflow argument applied to intersecting $D$-branes and use this to determine the eight-form gravitational coupling.Comment: 8 pages, harvmac, no figure

Subcritical Superstrings

We introduce the Liouville mode into the Green-Schwarz superstring. Like massive supersymmetry without central charges, there is no kappa symmetry. However, the second-class constraints (and corresponding Wess-Zumino term) remain, and can be solved by (twisted) chiral superspace in dimensions D=4 and 6. The matter conformal anomaly is c = 4-D < 1. It thus can be canceled for physical dimensions by the usual Liouville methods, unlike the bosonic string (for which the consistency condition is c = D <= 1).Comment: 9 pg., compressed postscript file (.ps.Z), other formats (.dvi, .ps, .ps.Z, 8-bit .tex) available at http://insti.physics.sunysb.edu/~siegel/preprints/ or at ftp://max.physics.sunysb.edu/preprints/siege

The group structure of non-Abelian NS-NS transformations

We study the transformations of the worldvolume fields of a system of multiple coinciding D-branes under gauge transformations of the supergravity Kalb-Ramond field. We find that the pure gauge part of these NS-NS transformations can be written as a U(N) symmetry of the underlying Yang-Mills group, but that in general the full NS-NS variations get mixed up non-trivially with the U(N). We compute the commutation relations and the Jacobi identities of the bigger group formed by the NS-NS and U(N) transformations.Comment: Latex, 11 pages. v2: Typos corrected; version to appear in JHEP