Effective Hamiltonians for Rapidly Driven Many-Body Lattice Systems: Induced Exchange Interactions and Density-Dependent Hoppings.

We consider 1D lattices described by Hubbard or Bose-Hubbard models, in the presence of periodic high-frequency perturbations, such as uniform ac force or modulation of hopping coefficients. Effective Hamiltonians for interacting particles are derived using an averaging method resembling classical canonical perturbation theory. As is known, a high-frequency force may renormalize hopping coefficients, causing interesting phenomena such as coherent destruction of tunneling and creation of artificial gauge fields.

Intrinsic photoconductivity of ultracold fermions in optical lattices.

We report on the experimental observation of an analog to a persistent alternating photocurrent in an ultracold gas of fermionic atoms in an optical lattice. The dynamics is induced and sustained by an external harmonic confinement. While particles in the excited band exhibit long-lived oscillations with a momentum-dependent frequency, a strikingly different behavior is observed for holes in the lowest band.

Directed transport in a classical lattice with a high-frequency driving.

We analyze the dynamics of a classical particle in a spatially periodic potential under the influence of a periodic in time uniform force. It was shown by S. Flach and coworkers [Phys.

Fermi acceleration in time-dependent rectangular billiards due to multiple passages through resonances.

We consider a slowly rotating rectangular billiard with moving boundaries and use canonical perturbation theory to describe the dynamics of a billiard particle. In the process of slow evolution, certain resonance conditions can be satisfied. Correspondingly, phenomena of scattering on a resonance and capture into a resonance happen in the system.

A novel human-specific soluble vascular endothelial growth factor receptor 1: cell-type-specific splicing and implications to vascular endothelial growth factor homeostasis and preeclampsia.

A human-specific splicing variant of vascular endothelial growth factor (VEGF) receptor 1 (Flt1) was discovered, producing a soluble receptor (designated sFlt1-14) that is qualitatively different from the previously described soluble receptor (sFlt1) and functioning as a potent VEGF inhibitor. sFlt1-14 is generated in a cell type-specific fashion, primarily in nonendothelial cells. Notably, in vascular smooth muscle cells, all Flt1 messenger RNA is converted to sFlt1-14, whereas endothelial cells of the same human vessel express sFlt1.

Integrability, stability, and adiabaticity in nonlinear stimulated Raman adiabatic passage.

We study the dynamics of a two-color photoassociation of atoms into diatomic molecules via nonlinear stimulated Raman adiabatic passage process. The system has a famous counterpart in (linear) quantum mechanics, and has been discussed recently in the context of generalizing the quantum adiabatic theorem to nonlinear systems. Here we use another approach to study adiabaticity and stability in the system: we apply methods of classical Hamiltonian dynamics.

Transgenic system for conditional induction and rescue of chronic myocardial hibernation provides insights into genomic programs of hibernation.

A key energy-saving adaptation to chronic hypoxia that enables cardiomyocytes to withstand severe ischemic insults is hibernation, i.e., a reversible arrest of contractile function.

Universality in nonadiabatic behavior of classical actions in nonlinear models of Bose-Einstein condensates.

We discuss the dynamics of approximate adiabatic invariants in several nonlinear models being related to the physics of Bose-Einstein condensates (BECs). We show that the nonadiabatic dynamics in Feshbach resonance passage, nonlinear Landau-Zener (NLZ) tunneling, and BEC tunneling oscillations in a double well can be considered within a unifying approach based on the theory of separatrix crossings. The separatrix crossing theory was applied previously to some problems of classical mechanics, plasma physics, and hydrodynamics, but has not been used in the rapidly growing BEC-related field yet.

VEGF-induced adult neovascularization: recruitment, retention, and role of accessory cells.

Adult neovascularization relies on the recruitment of circulating cells, but their angiogenic roles and recruitment mechanisms are unclear. We show that the endothelial growth factor VEGF is sufficient for organ homing of circulating mononuclear myeloid cells and is required for their perivascular positioning and retention. Recruited bone marrow-derived circulating cells (RBCCs) summoned by VEGF serve a function distinct from endothelial progenitor cells.

Ero1-L alpha plays a key role in a HIF-1-mediated pathway to improve disulfide bond formation and VEGF secretion under hypoxia: implication for cancer.

Oxygen is the ultimate source of oxidizing power for disulfide bond formation, suggesting that under limiting oxygen proper protein folding might be compromised. We show that secretion of vascular endothelial growth factor (VEGF), a protein with multiple disulfide bonds, was indeed impeded under hypoxia and was partially restored by artificial increase of oxidizing equivalents with diamide. Physiologically, the oxireductase endoplasmic reticulum oxidoreductin-1 (Ero1)-L alpha, but not other proteins in the relay of disulfide formation, was strongly upregulated by hypoxia and independently by hypoglycemia, two known accompaniments of tumors.

Specific induction of tie1 promoter by disturbed flow in atherosclerosis-prone vascular niches and flow-obstructing pathologies.

Nonlaminar flow is a major predisposing factor to atherosclerosis. Yet little is known regarding hemodynamic gene regulation in disease-prone areas of the vascular tree in vivo. We have determined spatial patterns of expression of endothelial cell receptors in the arterial tree and of reporter gene constructs in transgenic animals.

Transport in a slowly perturbed convective cell flow.

We study transport properties in a simple model of two-dimensional roll convection under a slow periodic (period of order 1/ varepsilon >>1) perturbation. The problem is considered in terms of conservation of the adiabatic invariant. It is shown that the adiabatic invariant is well conserved in the system.

Resonant phenomena in classical dynamics of three-body Coulomb systems.

We consider dynamics of a planar three-body Coulomb system similar to a hydrogen molecular ion (heavy-light-heavy particles). The system has three degrees of freedom. In the limit of infinitely heavy nuclei the system is reduced to the famous two-center problem which is integrable.

Conditional switching of VEGF provides new insights into adult neovascularization and pro-angiogenic therapy.

To gain insight into neovascularization of adult organs and to uncover inherent obstacles in vascular endothelial growth factor (VEGF)-based therapeutic angiogenesis, a transgenic system for conditional switching of VEGF expression was devised. The system allows for a reversible induction of VEGF specifically in the heart muscle or liver at any selected schedule, thereby circumventing embryonic lethality due to developmental misexpression of VEGF. Using this system, we demonstrate a progressive, unlimited ramification of the existing vasculature.

Comment on "pi kinks in strongly ac driven sine-Gordon systems".

V. Zharnitsky, I. Mitkov, and N.

A novel role for VEGF in endocardial cushion formation and its potential contribution to congenital heart defects.

Normal cardiovascular development is exquisitely dependent on the correct dosage of the angiogenic growth factor and vascular morphogen vascular endothelial growth factor (VEGF). However, cardiac expression of VEGF is also robustly augmented during hypoxic insults, potentially mediating the well-established teratogenic effects of hypoxia on heart development. We report that during normal heart morphogenesis VEGF is specifically upregulated in the atrioventricular (AV) field of the heart tube soon after the onset of endocardial cushion formation (i.

Selective ablation of immature blood vessels in established human tumors follows vascular endothelial growth factor withdrawal.

Features that distinguish tumor vasculatures from normal blood vessels are sought to enable the destruction of preformed tumor vessels. We show that blood vessels in both a xenografted tumor and primary human tumors contain a sizable fraction of immature blood vessels that have not yet recruited periendothelial cells. These immature vessels are selectively obliterated as a consequence of vascular endothelial growth factor (VEGF) withdrawal.

[Submerged esophago-intestinal anastomosis in surgical treatment of gastric cancer].

The short-term results of 1,605 gastrectomies performed for stomach cancer, using different types of esophagoenterostomy, are discussed. Anastomotic leakage is the main criterion for a choice of the most optimal procedure of forming an anastomosis. The contribution of the first and second rows of sutures to leakage is evaluated.

[Current principles of diagnosis and surgical treatment of non-organ retroperitoneal tumors].

The data on surgical treatment of 455 patients operated on for primary and recurrent non-organ retroperitoneal tumors (NRT) are discussed. 64.2% of tumors were resected; postoperative lethality was 8.

[Surgical treatment of adrenal gland tumors].

The data on surgical treatment of 146 patients with adrenal gland malignancies as well as literature on the problem are discussed.

Apposition-dependent induction of plasminogen activator inhibitor type 1 expression: a mechanism for balancing pericellular proteolysis during angiogenesis.

Plasminogen-activator inhibitor type I (PAI-1), the primary inhibitor of urinary-type plasminogen activator, is thought to play an important role in the control of stroma invasion by both endothelial and tumor cells. Using an in vitro angiogenesis model of capillary extension through a preformed monolayer, in conjunction with in situ hybridization analysis, we showed that PAI-1 mRNA is specifically induced in cells juxtaposed next to elongating sprouts. To further establish that PAI-1 expression is induced as a consequence of a direct contact with endothelial cells, coculture experiments were performed.

Translation of vascular endothelial growth factor mRNA by internal ribosome entry: implications for translation under hypoxia.

Vascular endothelial growth factor (VEGF) is a hypoxia-inducible angiogenic growth factor that promotes compensatory angiogenesis in circumstances of oxygen shortage. The requirement for translational regulation of VEGF is imposed by the cumbersome structure of the 5' untranslated region (5'UTR), which is incompatible with efficient translation by ribosomal scanning, and by the physiologic requirement for maximal VEGF production under conditions of hypoxia, where overall protein synthesis is compromised. Using bicistronic reporter gene constructs, we show that the 1,014-bp 5'UTR of VEGF contains a functional internal ribosome entry site (IRES).

Vascular endothelial growth factor upregulation in human central retinal vein occlusion.

Background And Objective: Vascular endothelial growth factor (VEGF), a key mediator of intraocular neovascularization, is triggered by hypoxia and has been shown in the eyes of animal models of central retinal vein occlusion (CRVO). However, there is little information on CRVO in humans, in particular, the identity of VEGF-producing cells.

Study Design: The study design was molecular localization of the site of VEGF production in the eyes of patients with CRVO.

Loss of ovarian function promotes angiogenesis in human ovarian carcinoma.

We show here that elevated levels of gonadotropins (luteinizing hormone and follicle stimulating hormone), as found in menopause or after ovariectomy, promote growth of human ovarian carcinoma by induction of tumor angiogenesis. Human epithelial ovarian cancer tumors progressed faster in ovariectomized mice. This induced growth could be attributed to the elevated levels of gonadotropins associated with loss of ovarian function because direct administration of gonadotropins also was effective in promoting tumor progression in vivo.

Rubeosis iridis in retinoblastoma. Histologic findings and the possible role of vascular endothelial growth factor in its induction.

Purpose: Iris neovascularization (rubeosis iridis) is a common finding in eyes harboring retinoblastoma. The purpose of the current study is to evaluate the histologic factors that may affect the development of rubeosis iridis in eyes with retinoblastoma and to examine whether vascular endothelial growth factor (VEGF), a hypoxia-induced angiogenic factor, is produced by hypoxic retinoblastoma and retinal cells in these eyes.

Materials And Methods: One hundred eighty-one enucleated eyes containing retinoblastoma were the source for the current study.