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We have previously characterized morphologic features of wounding-induced angiogenesis that occurs in response to acute and chronic gastric mucosal injury. As a means of investigating the molecular mechanisms underlying gastric angiogenesis, microvascular endothelial cells were isolated from stomachs of normal (non-injured) rats. The isolation procedure adapted and combined aspects of previous methods and employed positive selection using magnetic beads coated with monoclonal antibody specific for rat CD31 (PECAM-1), a cell surface marker restricted to platelets, monocytes, T lymphocytes and endothelial cells. The isolated microvascular endothelial cells expressed vascular endothelium-specific antigen and the endothelial-specific receptors, Tie2 and flt-1 (VEGFR1). When plated on growth factor-reduced matrigel, the isolated microvascular endothelial cells formed capillary-like structures reflecting in vitro angiogenesis. These cells were also responsive to vascular endothelial growth factor, VEGF, further verifying their endothelial nature. The rat microvascular endothelial cells isolated by this procedure should be useful in delineating molecular mechanisms and regulation of the angiogenesis that is essential for the healing of acute and chronic gastric injury.

Nitric oxide synthase is overexpressed in the portal hypertensive (PHT) esophagus, suggesting that expression of other vasoactive mediatora could also be affected. Therefore, in the present study we determined the expression of endothelin-1 (ET-1) and endothelin receptors, which could contribute to the regulation of the vascular tone in PHT esophagus. In esophageal specimens of PHT and sham operated rats, expression of ET-1 and its receptors A and B (ET(A)R and ET(B)R) mRNAs was studied by reverse transcription-polymerase chain reactions. ET-1 protein expression was assessed by immunostaining and enzyme immunoassay. In PHT esophagus, expression of ET-1, ET(A)R and ET(B)R mRNAs was significantly increased by 2.2-, 2.5- and 1.5-fold, respectively, compared with sham operated. The ET-1 protein was significantly increased by 2.2-fold vs. controls as measured by enzyme immunoassay. ET-1 protein was predominantly localized to endothelia of submucosal veins. Thus, portal hypertension induces over-expression of ET-1 in endothelia of esophageal submucosal vessels. Since ET-1 and its receptors could promote vascular proliferation and induce mucosal damage, the overexpressed ET-1 may play an important role in the development and rupture of esophageal varices in portal hypertension.

A study was conducted to analyze the magnetic characteristics of single-crystalline Mott insulator YVO3. The crystals were prepared using the floating-zone method. Experimental results indicated that the single crystal supports a couple of magnetic transitions at about 115 and 75 K. Findings also showed that anisotropic response with the c axis is the easy-magnetization direction.

The magnetic properties of single-crystalline SrLaFeO4 and Sr1.1La0.9FeO4 are reported. Both the compounds crystallize in the tetragonal K2NiF4 structure with the La and Sr atoms randomly distributed over the 4e crystallographic sites of the structure.

We synthesized Ca1−xSrxFeO3 containing tetravalent iron Fe4+ with high valence by low temperature heat treatment along with ozone oxidization. We investigated the magnetic properties of perovskite Ca1−xSrxFeO3. The charge disproportionation transition temperature (TCD) of Ca1−xSrxFeO3 was observed from x = 0.0 to 0.6 in the magnetic susceptibility measurements. The decrease in TCD occurs is attributed to deformation of the crystal structure. The metamagnetic transitions with hysteresis were observed in the magnetization curves of all the compositions. The metamagnetic behavior is due to helical magnetism, which means that there are intermediate stable states before magnetization is saturated. In the Sr-rich region with x = 0.8 and 1.0, the saturation magnetization shows forced ferromagnetic order with a value of ∼3.2 μB at high magnetic field, H ∼ 60 T. [ABSTRACT FROM AUTHOR]

We synthesized Ca1−xSrxFeO3 containing tetravalent iron Fe4+ with high valence by low temperature heat treatment along with ozone oxidization. We investigated the magnetic properties of perovskite Ca1−xSrxFeO3. The charge disproportionation transition temperature (TCD) of Ca1−xSrxFeO3 was observed from x = 0.0 to 0.6 in the magnetic susceptibility measurements. The decrease in TCD occurs is attributed to deformation of the crystal structure. The metamagnetic transitions with hysteresis were observed in the magnetization curves of all the compositions. The metamagnetic behavior is due to helical magnetism, which means that there are intermediate stable states before magnetization is saturated. In the Sr-rich region with x = 0.8 and 1.0, the saturation magnetization shows forced ferromagnetic order with a value of ∼3.2 μB at high magnetic field, H ∼ 60 T. [ABSTRACT FROM AUTHOR]

We report on the magnetic properties of single-crystalline SrLaFeO4 and Sr1.1La0.9FeO4. Both compounds crystallize in the tetragonal K2NiF4 structure (I4 /mmm) with the La and Sr atoms randomly distributed over the 4e crystallographic sites of this structure. SrLaFeO4 orders antiferromagnetically below 350 K, and Sr1.1La0.9FeO4, orders antiferromagnetically at about 150 K. Both compounds exhibit magnetic structures described by orthorhombic Cmca-type symmetry and two magnetic propagation vectors q1=(1/2 , 1/2 ,0) and q2=s-1/2 , 1/2 ,0), representing the two possible magnetic domains. A collinear antiferromagnetic arrangement of the Fe3+ moments confined to the tetragonal basal plane is found. Bulk magnetic studies on SrLaFeO4 show that the properties of this compound are highly anisotropic, and there is evidence for additional magnetic transitions at lower temperatures (30 and 90 K). Low-temperature neutron diffraction data were taken to gain some insight into the nature of these transitions. [ABSTRACT FROM AUTHOR]