128 research outputs found
Grassmann Duality for D-modules
No full textWe generalize the main results on projective duality to the case of the correspondence between "dual" Grassmann manifolds G and G*. The new aspect is that the "incidence variety" S subset of G x G* is no longer smooth, a fact which requires the tools of the theory of b-functions. In particular, we obtain an equivalence between the categories of sheaves on G and G*, as well as between those of D-modules; then, quantizing this equivalence, we explicitly calculate the transform of a D-module associated to a holomorphic line bundle
Contributo preliminare allo studio dei castelli in area collinare: i casi di Castelrotto e Marano in Valpolicella (VR)
No full textSynthesis and biological properties of C-terminal vinyl ketone pseudotripeptides
No full textThe ubiquitin-proteasome pathway responsible for the turnover of many cellular proteins represents an attractive target in the development of new drug therapies: In particular, modulation of the proteasome activity by specific inhibitors may represent a useful tool for the treatment of tumours. Here, we report synthesis and activity of a new series of oligopseudopeptide analogues bearing a vinyl ketone pharmacophoric unit at the C-terminal position. Some derivatives showed inhibition in the mu M range of the trypsin-like (T-L) active site of the proteasome
Generalized Verma modules, b-functions of semi-invariants and duality for twisted D-modules on generalized flag manifolds
No full textLet G be a connected semisimple algebraic group over C, P a parabolic subgroup, g and p their Lie algebras. We prove a microlocal version of Gyoja's conjectures about a relation between the irreducibility of generalized Verma modules on g induced from p and the zeroes of b-functions of P-semiinvariants on G. Our method uses a duality for twisted D-modules on generalized flag manifolds
Real forms of the Radon-Penrose transform
No full textThe complex Radon correspondence relates an n-dimensional projective space
with the Grassmarm manifold of its p-dimensional planes. This is the geometric
background of the Radon-Penrose transform, which intertwines cohomology classes of
homogeneous line bundles with holomorphic solutions to the generalized massless field
equations. A good framework to deal with such problems is provided by the recently
developed theory of integral transforms for sheaves and D-modules. In particular,
an adjunction formula describes the range of transforms acting on general function
spaces, associated with constructible sheaves.
The linear group SL(n + 1,C) naturally acts on the Radon correspondence. A
distinguished family of function spaces is then the one associated with locally constant
sheaves along the closed orbits of the real forms of SL(n + 1, C). In this paper, we
systematically apply the above-mentioned adjunction formula to such function spaces.
We thus obtain in a unified manner several results concerning the complex, conformal,
or real Radon transforms
C-terminal trans,trans-muconic acid ethyl ester partial retro-inverso pseudopeptides as proteasome inhibitors
No full textThe development of specific inhibitors of the proteasome represents an important opportunity for new drug therapies. The central role of the multicatalytic complex in the intracellular proteolysis mediated by ubiquitin-proteasome pathway goes to discovery many molecules able to selectively inhibits enzymatic active subsites. Now, we report synthesis and activity of a new partial retro-inverso oligopseudopeptide derivatives bearing a trans, transmuconic acid ethyl ester pharmacophoric unit at the C-terminal. Some analogues selectively inhibited in mu M range the caspase-like (C-L) activity in the beta 1 subunit of the proteasome
A diffuse glioma with oligodendroglial‐like cells and extensive calcifications
No full text: The tumor showed extensive microcalcifications and cells with oval, nuclei and a clear perinuclear halo (A), positive immunostaining for OLIG-2 (B), GFAP (C), and CD34 (D), and intermingled Neu-N-positive neurons (E). FISH revealed multiple signals for the centromere of chromosome 7 (gains) (green probe) and the EGFR locus (red probe) (F, left), and a single signal for the centromere of chromosome 10 (loss) (F, right)
Effects of peptide T derivatives on the proliferation of cultured human keratinocytes.
No full text[D-Ala1]peptideT-amide, the linear hexapeptide H-Thr-Hse-Asn-Tyr-Thr-Asp-OH (LPT) and its cyclic analog, cyclo(-Thr-Hse-Asn-Tyr-Thr-Asp-) (CPT), were tested for their effects on the proliferation of cultured normal human keratinocytes (KTs) in comparison with vasoactive intestinal peptide (VIP). [D-Ala1]PT-NH2, LPT and VIP (all 0.1 mumol/l) increased the cell number in KT cultures, whereas CPT was ineffective. The VIP antagonist [N-Ac-Tyr1,D-Phe2]GRF (1-29)-NH2 significantly inhibited the VIP effects on KTs. On the other hand this antagonist did not affect the peptide T (PT) compounds-induced stimulation of KTs, providing indirect evidence that the mitogenic effects of VIP and PT peptides are probably mediated via different receptors
Structure-activity relationships of peptide T-related pentapeptides
No full textFifteen pentapeptide analogs of C-terminal fragment of peptide T, H-Ala-Ser-Thr-Thr-Thr-Asn-Tyr-Thr-OH, were prepared and tested for human monocyte chemotaxis. Structure-activity studies suggest that the potent chemotactic activity of H-Thr-Thr-Asn-Tyr-Thr-OH is mediated through the polar properties of the C-terminal carboxyl group and Thr side chains at the critical positions 5 and 8, while the hydroxyl group of N-terminal Thr and its free amino function are not essential requirements for CD4 receptor interactions
- …
