Hypoxia and vascular endothelial growth factor stimulate angiogenic integrin expression in bovine retinal microvascular endothelial cells

PURPOSE: Integrins alphavbeta3 and alphavbeta5 are cell-to-matrix adhesion molecules that have been reported to mediate vascular cell proliferation and migration. The authors investigated the regulation of expression of these angiogenic integrins by hypoxia and vascular endothelial growth factor (VEGF) in retinal microvascular endothelial cells in culture. METHODS: Cultured bovine retinal capillary endothelial cells were exposed to human recombinant VEGF under normoxic (95% air, 5% CO2) conditions to assess the effects of VEGF. Hypoxia studies were performed under lower oxygen concentration (0.5%-1.5% O2) induced by nitrogen replacement in constant 5% CO2 conditions. Integrin family mRNA and protein expression were assessed by northern blot analysis and immunoprecipitation. RESULTS: VEGF (25 ng/ml) increased integrin alphav, beta3, and 35 mRNA after 24 hours 6.1+/-0.8-fold (P < 0.001), 5.9+/-1.1-fold (P < 0.001), and 1.9+/-0.2-fold (P < 0.01), respectively. Similarly, hypoxia stimulated gene expression of integrin alphav and beta3 after 24 hours by 5.1+/-1.7-fold (P < 0.01) and 3.0+/-0.5-fold (P < 0.01), respectively, and integrin beta5 after 9 hours 1.4+/-0.2-fold (P < 0.05). This hypoxia-induced, integrin alphav mRNA elevation was inhibited significantly by anti-VEGF neutralizing antibody. Also, a conditioned medium from confluent endothelial cells maintained under hypoxic conditions for 24 hours produced a 7.1+/-1.1-fold increase (P < 0.001) in integrin alphav mRNA expression after 24 hours, which was reversed by anti-VEGF neutralizing antibody. Induction of integrin alphav by VEGF and hypoxia was confirmed in the protein level. CONCLUSIONS: These data suggest that hypoxia stimulates expression of vascular integrins alphavbeta3 and alphavbeta5 in retinal microvascular endothelial cells partially through autocrine-paracrine action of VEGF induced by the hypoxic state.     

Early HCC and adenomatous hyperplasia: evaluation of arterial and portal blood flow with CTA, CTAP, and pathologic correlation

In order to analyze the hemodynamic properties of early hepatocellular carcinoma (HCC) and adenomatous hyperplasia (AH), three lesions (two HCCs, one AH) depicted as hypoattenuating at CTA and iso attenuating at CTAP were correlated with the histopathological findings. The number of normal hepatic arteries in the tumor was lower than in the liver. Degeneration and narrowing of the lumens were also seen microscopically. All tumors showed the replacing growth pattern and had similar numbers of the portal tracts in the tumor to the liver. The decreased number of intratumoral normal arteries is suspected to be a characteristic finding of the early stage of HCC.     

A potential molecular approach to ex vivo hematopoietic expansion with recombinant epidermal growth factor receptor-expressing adenovirus vector

Ex vivo expansion of hematopoietic stem cell (HSC) is an attractive technology for its potency of a variety of clinical applications. Such a technology has been achieved to some extent with combinations of various cytokines or continuous perfusion cultures. However, much more improvement is required especially for expansion of primitive hematopoietic progenitors. We propose here a novel molecular approach that might have the potential to compensate the current expansion. We designed an adenovirus vector to transiently express human epidermal growth factor receptor (EGFR), which is known to transduce only a mitogenic, but not a differentiation signal to mouse bone marrow cells on human purified CD34+ peripheral blood (PB) cells, and tried to expand these cells with EGF ex vivo. Because we found that exposure of CD34+ PB cells to cytokines induced surface expression of adenovirus-internalization receptor and rendered these cells permissive to adenovirus infection, we infected these cells with the adenovirus vector carrying EGFR gene in the presence of cytokines. Two-color flow cytometric analysis demonstrated that 60.3% +/- 22.4% of CD34+ cells expressed the adenovirus-mediated EGFR. Moreover, long-term culture-initiating cell assay showed that adenovirus vector could transduce more primitive progenitors. Subsequently, we tried to expand these cells in suspension culture with EGF for 5 days. Methylcellulose clonal assay showed that EGF induced 5.0- +/- 2.4-fold proliferation of the colony-forming unit pool during 5 days of expansion. The simple procedure of efficient adenovirus gene delivery to immature hematopoietic cells proved promising, and this technique was potentially applicable for a novel strategy aiming at ex vivo expansion of hematopoietic progenitors.     

THE ROLE OF NATURAL CONVECTION DURING MELTING AND SOLIDIFICATION OF PCM IN A VERTICAL CYLINDER

Measurements of heat transfer during melting and solidfkation of n-eicosane and rt-hexadecane were performed in vertical cylinders with two different lengths and diameters. Radial temperature distibutions were measured with lime at different heights in all the tests. To evaluate the rate of heat charged and discharged from the cylinder at different heights, the data were recorded and processed directly usinj; on-line computer. A theoretical model was developed based on solving the one-dimensional unsteady heat conduction equation in both phases. Convection in the liquid was included using an effective thermal conductivity; a lumped parameter that includes also the effect of the two-dimensional heat transfer during melting. The model, which may be used for the prediction of both melting and solidfkation experiments, takes into account the effect of initial subcooling or superheating and includes the heat capacity of the cylinder containing the PCM. The agreement of the model was good not only with the experimental results of this work, but also with the published work of the others.     

The effect of temperature on the growth of microbial film in a model trickling filter

The daily weight change of a microbial film in a model filter after the start of synthetic feed application was observed and the effect of temperature on the growth of the film was studied. The rate of BOD removal, the rate at which SS was washed out, the yield coefficient and the autolysis coefficient were chosen as the factors related to the growth of the film and the effects of temperature on them were examined.The growth pattern of the film can be divided into the lag-phase, growth-phase and stationary-phase. The growth equation of the film in the growth-phase was obtained by assuming that the rates of BOD removal and SS washed out were constant.In order to evaluate the growth of the film at various temperatures, the growth capacity and the mean growth rate were defined. The growth capacity is the film weight at the stationary-phase and expresses the maximum weight to which the film can increase in a given filter. The growth capacity increased as the temperature fell. This is due to the autolysis coefficient which becomes lower at low temperatures. The period necessary to reach the stationary-phase was shorter at high temperatures. The mean growth rate, which was defined as the rate when the film has reached half the growth capacity, was at its maximum at 15°C.     

Glycine 85 of the trp-repressor of E.coli is important in forming the hydrophobic tryptophan binding pocket: experimental and computational approaches

Experimental and computational analyses were performed on thecorepressor (L-tryptophan) binding site of the trp-repressorof Escherichia coli to investigate the ligandprotein interactions.Gly 85, one of the residues forming the hydrophobic pocket ofthe binding site, was systematically replaced with Ala, Val,Leu and Trp by cassette mutagenesis. Biochemical characterizationshowed that all these mutations caused significant decreasesin tryptophan binding activity. Free energy perturbation calculationswere performed for the mutants and were consistent with theexperimental results. The lack of a side chain at position 85was concluded to be essential for binding the corepressor; thestructure of the binding pocket was suggested to be tight inthe vicinity of Gly85.     

Formation of carbonaceous mesophase at lower temperature

The effects of heat-treatment at lower temperature on the formation of carbonaceous mesophase were studied. Heat-treatments of QS pitch below 340°C and of KF asphalt below 370°C lead to the formation of mesophase spherules having a different structure from those found previously. For QS pitch, the lowest temperature of mesophase formation was 290°C but more than one month was required for heat-treatment. The structure of the fourth-type spherule is proposed from the microscopic observations and its orientational behavior in a magnetic field. The structure of this type is very similar to that of the Brooks-Taylor-type one, and it is believed that the fourth-type spherule is a meta-stable phase of the Brooks-Taylor-type one.     

Smart Processing Development of Photonic Crystals and Fractals

A new concept of smart processing is proposed that can produce advanced materials and components by finely controlling processing energy and engineering structures. New functional components of 3D photonic crystals and fractals are demonstrated, which are constructed of dielectric ceramics and a polymer using a CAD/CAM stereolithography system. By modifying the structure of diamond-like photonic crystals using free-form fabrication, electromagnetic waves can be controlled, opening the way for new applications in communication and sensing technology. The photonic fractal, a new material that can strongly localize electromagnetic waves without reflection and transmission, will also lead to new applications in the energy and medical fields.