Recoil frame photoelectron angular distributions of BF3: a sensitive probe of the shape resonance in the F 1s continuum.

Recoil frame photoelectron angular distributions (RFPADs) of BF(3) molecules are presented over the energy region of the shape resonance in the F 1s continuum. Time-dependent density functional theory calculations are also given to understand the shape resonance dynamics. The RFPADs have been compared with the theoretical calculations. It is found that the RFPADs calculated by the localized core-hole model are in better agreement with the experimental, compared with those by the delocalized core hole. Dipole matrix elements and dipole prepared continuum wavefunctions show that the shape resonance in the F 1s ionization continuum of BF(3) is induced by p-partial waves as previously reported by Swanson et al. [J. Chem. Phys. 75, 619 (1981)]. However, due to the couplings with the other partial waves the feature characteristic of the p-partial waves has not been observed in the RFPADs.

Ephrin-B1 localizes at the slit diaphragm of the glomerular podocyte.

Ephs and ephrins are a family of membrane-bound proteins that function as receptor-ligand pairs. Members of the Eph-ephrin-B family have recently been reported to regulate the paracellular permeability of epithelial cells. In this study, we analyzed the expression and the function of ephrin-B1 in glomeruli. Using immunofluorescence (IF), we found that ephrin-B1 was expressed along the glomerular capillary loop. Immunoelectron microscopy revealed that ephrin-B1 expression was restricted at the slit diaphragm. Dual labeled IF showed ephrin-B1 colocalized with the slit diaphragm proteins nephrin and CD2-associated protein. Ephrin-B1 colocalized with nephrin at the late capillary loop stage of kidney development. Additionally, injection of rats with a nephritogenic anti-nephrin antibody (ANA) reduced ephrin-B1 expression. When podocytes were cultured in vitro, they extruded processes that co-stained for ephrin-B1 and for CD2-associated protein. When these podocytes were treated in culture with small interfering RNA for ephrin-B1, CD2-associated protein was reduced in the processes, with a remaining faint perinuclear staining. We suggest that ephrin-B1 has a role in maintaining barrier function at the slit diaphragm.

Brassinosteroid-6-oxidases from Arabidopsis and tomato catalyze multiple C-6 oxidations in brassinosteroid biosynthesis.

Brassinosteroids (BRs) are steroidal plant hormones that are essential for growth and development. It has been proposed that BRs are synthesized via two parallel pathways, the early and late C-6 oxidation pathways according to the C-6 oxidation status. The tomato (Lycopersicon esculentum) Dwarf gene encodes a cytochrome P450 that has been shown to catalyze the C-6 oxidation of 6-deoxocastasterone to castasterone. We isolated an Arabidopsis ortholog (AtBR6ox gene) of the tomato Dwarf gene. The encoded polypeptide has characteristics of P450s and is classified into the CYP85 family. The AtBR6ox and tomato Dwarf gene were expressed in yeast and the ability of the transformed yeast cells to metabolize 6-deoxo-BRs was tested. Metabolites were analyzed by gas chromatography-mass spectrometry. Both enzymes catalyze multiple steps in BR biosynthesis: 6-deoxoteasterone to teasterone, 3-dehydro-6-deoxoteasterone to 3-dehydroteasterone, 6-deoxotyphasterol to typhasterol, and 6-deoxocastasterone to castasterone. Our results indicate that the AtBR6ox gene and the tomato Dwarf gene encode steroid-6-oxidases and that these enzymes have a broad substrate specificity. This suggests that the BR biosynthetic pathway consists of a metabolic grid rather than two separate parallel pathways.

Search for naturally occurring substances to prevent the complications of diabetes. II. Inhibitory effect of coumarin and flavonoid derivatives on bovine lens aldose reductase and rabbit platelet aggregation.

An EtOAc extract of Artemisiae Capillari Spica inhibited both bovine lens aldose reductase (bovine-LAR) and rabbit platelet aggregation. Two simple coumarins, scoparone (1) and scopoletin (2), and three flavonoids, capillarisin (21), cirsimaritin (22) and rhamnocitrin (23), were isolated from this extract. Scoparone (1) and scopoletin (2) exhibit a potent inhibitory effect on rabbit platelet aggregation induced by four types of agent, ADP, PAF, sodium arachidonate and/or collagen. Capillarisin (21) exhibits a potent inhibitory effect on bovine-LAR. In addition, thirteen simple coumarins, five coumarin glycosides and two flavonoids were tested for their inhibitory effect against bovine-LAR and rabbit platelet aggregation.

Affinity gel electrophoresis of nucleic acids. Nucleobase-selective separation of DNA and RNA on agarose-poly(9-vinyladenine) conjugated gel.

Poly(9-vinyladenine) (PVAd) was immobilized within an agarose gel matrix to produce a novel affinity gel for the base-specific separation of nucleic acids by electrophoresis. The shape (single- or double-stranded) and base content of nucleic acids were specifically recognized by the affinity gel. Only single stranded DNA, of which the sequence is not regular enough to form a stable duplex hairpin structure, was selectively absorbed over double-stranded DNA. Among five polynucleotides having different bases such as poly(A), poly(G), poly(C), poly(U) and poly(I), poly(U) and poly(I) were base-specifically adsorbed by PVAd, probably by hydrogen bond formation. The effect of the molecular mass and size of poly(9-vinyladenine) was also examined.

Affinity gel electrophoresis of nucleic acids. Specific base- and shape-selective separation of DNA and RNA on polyacrylamide-nucleobase conjugated gel.

Two types of affinity gels consisting of cross-linked polyacrylamide and affinity ligands possessing nucleic acid bases were prepared. One type of gel was polyacrylamide-poly(vinylnucleobase) conjugated gel, where the poly(vinylnucleobase) such as poly(9-vinyladenine) (PVAd) bearing a nucleobase in the side-chain was entrapped in the gel matrix. The other type of gel, in which a nucleobase such as adenine is chemically bonded to polyacrylamide gel, was prepared by copolymerization of acrylamide, cross-linker and 9-vinyladenine. These affinity gels, especially the former, demonstrated characteristic nucleobase- and shape-selective separation of nucleic acids. The gels showed high affinity for single-stranded DNA and both single- and double-stranded polynucleotides and could separate a double-stranded DNA in mixtures of double-stranded DNA and polynucleotides. The electrophoretic mobilities of poly(uridylic acid) and poly(inosinic acid) were selectively retarded even in the presence of 7 M urea. The electrophoretic behaviours of nucleic acids on the polyacrylamide-PVAd conjugated gels were compared with those on the agarose-PVAd conjugated gel. The effects of urea, temperature and concentration of PVAd were also examined. The polyacrylamide-PVAd conjugated gel served to elucidate interactions between PVAd and nucleic acids that could not be detected by usual spectroscopic methods.

Dissociation of hemodynamic and coronary arterial tolerance to nitroglycerin in dogs.

To investigate the development of tolerance to nitroglycerin (NTG), therapeutic doses of NTG (1 microgram/kg/min in group 1G and 10 micrograms/kg/min in group 10G) or vehicle alone (group 0G) were infused intravenously (i.v.) for 24 h into anesthetized mongrel dogs. The reduction of pulmonary artery pressure (PAP) by NTG was attenuated after the first 3 and 6 h of NTG infusion in groups 1G and 10G, respectively. At the end of infusion, coronary artery strips were excised for study of isometric tension responses to cumulative doses of NTG. The ED50 value for group 10G (17.5 +/- 2.9 nM) was greater than that for group 0G (5.2 +/- 1.1 nM, p < 0.001), but the ED50 value of group 1G (5.5 +/- 0.7 nM) was not. Maximum relaxation did not alter in the three groups. The concentration of cyclic GMP in the isolated coronary artery strips was measured by radioimmunoassay (RIA). Administration of 10(-8.5) M NTG increased the cyclic GMP level in group 0G (42.7 +/- 1.5%, p < 0.05) and group 1G (38.8 +/- 10.5%, p < 0.05), but not in group 10G (3.5 +/- 5.6%). The degree of increment in cyclic GMP corresponded with the relaxation response to 10(-8.5) M NTG. These results demonstrated the hemodynamic tolerance to NTG is different from vascular tolerance at therapeutic doses.

Spectroscopic study of the interaction between poly-(9-vinyladenine) and single or multistrand RNA.

The interaction between poly(9-vinyladenine) (PVAd) and poly[r(U)] was investigated by means of uv, CD, 1H-, and 31P-nmr spectroscopies. The interaction was dependent on the molecular weight of PVAd determined by uv and CD spectroscopies. Based on imino proton nmr, it was clearly found that PVAd formed the complex with poly[r(U)] by complementary hydrogen bonding. The interaction of PVAd with double- and triple-stranded helices of RNA was also investigated by uv melting behavior and 31P-nmr spectroscopy. The results suggested that PVAd could not interact with the double-stranded poly[r(A)].poly[r(U)] but did with the triple-stranded RNA.

High-performance affinity chromatography of oligonucleotides on nucleic acid analogue immobilized silica gel columns.

The nucleic acid analogues poly(9-vinyladenine) (PVAd), poly(9-adenylethyl methacrylate) and poly(thymylethyl methacrylate) (PTM) were chemically bonded to porous silica gel, which had been pretreated with 3-trimethoxysilylpropyl methacrylate, by free radical copolymerization to produce novel packing materials for affinity chromatographic columns. The columns separated nucleosides and nucleotide dimers on the basis of hydrophobic interaction using an aqueous buffer and complementary hydrogen bonding interaction in methanol as an eluent. The PVAd- and PTM-silica gel columns gave a nucleobase-selective separation of oligonucleotides differing in length from mixtures of oligoadenylic and oligouridylic acids. On the PVAd-silica gel column terminal phosphate isomers of oligouridylic acid up to seven mer were resolved and the elution order of the isomers was different from that on an ODS column.

Limitations of compensation by endogenous atrial natriuretic peptide in heart failure.

To evaluate the role of endogenous atrial natriuretic peptide (ANP) in patients with congestive heart failure (CHF), the relationship between plasma ANP and cyclic guanosine monophosphate (cGMP) levels and the prognosis of patients with CHF was examined. In patients with chronic mild to moderate CHF, there was a positive correlation between plasma ANP and cGMP levels (r = 0.81, p less than 0.001). However, there was no significant correlation between these plasma levels in patients with chronic severe CHF, in whom the cGMP concentration reached a plateau in spite of high levels of ANP. The ANP extraction level and the cGMP production level in the pulmonary and systemic circulation correlated significantly in patients with mild CHF. In contrast, there was no significant correlation between the 2 parameters in patients with severe CHF, and the molar ratios of cGMP production to ANP extraction in the pulmonary and systemic circulation were significantly lower than those in patients with mild CHF. In 44 patients with chronic severe CHF who were followed up over 2 years, plasma ANP levels provided more sensitive and specific prognostic information than any other parameters. These results indicate that ANP receptors coupled to guanylate cyclase may be down-regulated in patients with chronic severe CHF, suggesting that high plasma ANP levels as a prognostic predictor may be associated with limitations of compensation by endogenous ANP.

Study on the interaction of aromatic dyes with nucleic acids by means of UV, CD and NMR spectroscopies.

The interaction of several aromatic cationic dyes such as, ethidium bromide (EB), methylene blue (MB), acridine orange (AO), and Hoechst 33258 with calf-thymus DNA and poly(A)-poly(U) duplex was investigated. The different induced extrinsic Cotton effects (greater than 300 nm) were observed for DNA- and RNA-dye complexes. The binding properties of these complexes were examined by UV, CD, and NMR spectroscopies.

Affinity chromatography of nucleosides and nucleic acid base derivatives with nucleic acid bases or nitrobenzeneboronic acid substituted silicas.

Nucleic acid bases such as adenine and uracil, and nitrobenzeneboronic acid substituted silicas were prepared by the reaction of chloromethylbenzene substituted silica with adenine sodium salt and trimethylsilylated uracil, and nitration of benzeneboronic acid substituted silica, respectively. From the results of HPLC of nucleosides and N-ethyl derivatives of nucleic acid bases using modified silicas, hydrophobic base stacking interaction, selective hydrogen bonding interaction between purine and pyrimidine bases, and reversible cyclic boronate ester formation between diols of nucleosides with boronic acid were effective for the separation of nucleic acid related compounds. Moreover, association constants for hydrogen bonding formation of nucleic acid bases were estimated.