Hückel framework study on the superconducting vibronic interaction in (AB) N chains

Superconducting vibronic interaction in the vibronic superconductivity motif has been studied in the Hückel framework for (AB) _N chain systems. Within the on-site and nearest-neighbor approximation a new vibronic constant, /L, has been introduced, of which the importance has been discussed. The effect of the vibronic operator, , has also been studied. It is also concluded that the size-dependence of the superconducting vibronic interaction also exists in the (AB) _N chain systems.On leave from the Changchun Institute of Applied Chemistry, Academia Sinica, Changchun, P. R. China, as an STA fellowship awardee hosted by the Institute of Physical and Chemical Research of Japan.     

Characterization of the replication of Escherichia coli DNA in the absence of protein synthesis: Stable DNA replication

After inhibiting DNA synthesis in Escherichia coli, repeated cycles of chromosome replication can occur in the absence of protein synthesis. This “stable” replication requires the products of all of the known dna genes.Stable replication results from inhibiting DNA synthesis by treatment with naladixic acid, cytosine arabinoside or hydroxyurea; or by placing dnaB, dnaE or dnaG mutants at non-permissive temperatures. It also follows a “shift-up” into rich medium in which RNA and protein are synthesized more rapidly than DNA. Paradoxically, stable replication is induced also by treatment with concentrations of streptolydigin which do not inhibit DNA replication but temporarily and partially inhibit RNA and protein synthesis. During all of these treatments, some protein synthesis must occur.Stable replication is not immediately expressed after a short period of thymine starvation or streptolydigin treatment, but requires a subsequent period of protein synthesis. Once established, however, the stable replication state is permanent and will persist in the absence of protein synthesis or during normal growth.After stable replication has been determined by a period of DNA inhibition, it is possible to inactivate replication by heating dnaA, B, C, E and G temperature-sensitive mutants. However, resynthesis of these gene products in the presence of thymine and at the permissive temperature restores stable replication activity. Since restoration of activity can occur under normal growth conditions which do not induce stable replication, it was concluded that the dnaA, B, C, E and G gene products do not directly determine the stabilized character of the replication fork.A model is presented which attempts to explain the ability of different treatments to induce stable replication.     

Fucosyl-GM1a, an endoglycoceramidase-resistant ganglioside of porcine brain

The use of bovine brain has been prohibited in many countries because of the world-wide prevalence of mad cow disease, and thus porcine brain is expected to be a new source for the preparation of gangliosides. Here, we report the presence of a ganglioside in porcine brain which is strongly resistant to hydrolysis by endoglycoceramidase, an enzyme capable of cleaving the glycosidic linkage between oligosaccharides and ceramides of various glycosphingolipids. Five major gangliosides (designated PBG-1, 2, 3, 4, 5) were extracted from porcine brain by Folch's partition, followed by mild alkaline hydrolysis and PBA column chromatography. We found that PBG-2, but not the others, was strongly resistant to hydrolysis by the enzyme. After the purification of PBG-2 with Q-Sepharose, Silica gel 60 and Prosep-PB chromatographies, the structure of PBG-2 was determined by GC, GC-MS, FAB-MS and NMR spectroscopy as Fucalpha1-2Galbeta1-3GalNAcbeta1-4(NeuAcalpha2-3)Galbeta1-4Glcbeta1-1'Cer (fucosyl-GM1a). The ceramide was mainly composed of C18:0 and C20:0 fatty acids and d18:1 and d20:1 sphingoid bases. The apparent kcat/Km for fucosyl-GM1a was found to be 30 times lower than that for GM1a, indicating that terminal fucosylation makes GM1a resistant to hydrolysis by the enzyme. This report indicates the usefulness of endoglycoceramidase to prepare fucosyl-GM1a from porcine brain.     

Molecular Orbital Study of the Magnetic Properties of Pyrazine- and Pyrimidine-Bridged Copper(II) Complexes

Magnetic interactions in the three copper(II)-complex polymers, [Cu(PZ)(NO₃)₂]_n, [Cu(PM)(NO₃)₂(H₂O)₂]_n, and [Cu(PM)₂(NO₃)₂]_n are discussed on the basis of extended Hückel calculations inthe formulas PZ and PM stand for pyrazine and pyrimidine, respectively. Interactions between the Cu-3d orbitals and the lone-pair orbitals of pyrazine and pyrimidine are analyzed from the viewpoint of `through-space' and `through-bond' interactions using binuclear complexes to model the three copper(II) polymers. Three conclusions can be drawn from the orbital interaction analysis: (1) in the first polymer, a superexchange pathway is formed with the bond of Cu–-N and the through-bond interaction between the lone pairs of the nitrogen atoms of pyrazine will lead to an antiferromagnet state; (2) in the second polymer a superexchange pathway is formed with the bond of Cu–-N and the through-space interaction between the lone pairs of the nitrogen atoms of pyrimidine, and as a result an antiferromagnetic state will be preferred; and (3) in the third polymer., there is no effective pathway in respect of overlap interaction and the HOMO and the LUMO are actually degenerate, and thus a ferromagnetic state will arise. The band structures are analyzed to characterize the magnetic properties of the antiferromagnetic polymers, [Cu(PZ)(NO₃)₂]_n and [Cu(PM)(NO₃)₂(H₂O)₂], and the ferromagnetic polymer, [Cu(PM)₂(NO₃)₂]_n.     

Food source of riparian spiders analyzed by using stable isotope ratios

We analyzed the food source of riparian spiders in a middle reach of the Chikuma River, Japan, by using stable isotope ratios of carbon and nitrogen. The carbon and nitrogen isotope ratios of attached algae were higher than those of terrestrial plants, reflecting a large carbon isotope fractionation in terrestrial plants and a difference in nitrogen sources. The carbon isotope ratios of terrestrial insects were similar to those of the terrestrial plants, and the ratios of aquatic insects were scattered between those of the terrestrial plants and the attached algae. The carbon and nitrogen isotope ratios of spiders were intermediate between those of the terrestrial and aquatic insects. The two-source mixing model using the carbon isotope ratio showed that the web-building spiders utilized both the terrestrial and aquatic insects, with large contribution by the aquatic insects (54% on average with a maximum of 92% among spiders taxa collected in each zone), in the riparian area in a middle reach of the Chikuma River. The large contribution of the aquatic insects was often observed for the spiders collected near river channel (<5m) and for the horizontal web-building spiders collected across the riparian area. The relative contribution of the aquatic insects might be related with food availability (distance from river channel) and spiders food preference reflected in their web types (horizontal vs. vertical). Our results showed that organic materials produced in the river channel, in the riparian area, and in the terrestrial area surrounding the riparian area were mixed at the carnivorous trophic level of riparian spiders.     

Plasma adrenomedullin concentration is increased in patients with peripheral arterial occlusive disease associated with vascular inflammation

Adrenomedullin (AM), a potent vasodepressor, is known to have anti-atherosclerotic and anti-inflammatory effects. However, there is no information about its level in severe atherosclerotic diseases, such as peripheral arterial occlusive disease (PAOD). The present study investigated the plasma concentration of AM and several inflammatory parameters in 72 patients with and without PAOD. The plasma AM concentration in patients with PAOD was significantly higher than in those without PAOD. Its concentration had significant correlations with ankle-brachial index and Fontaine's stage. The plasma AM level also correlated with high sensitive C-reactive protein and interleukin-6. As an additional study, plasma levels of two forms of AM drawn from the femoral artery and saphenous vein were measured in 27 other subjects. Both mature and intermediate forms of plasma AM in the femoral artery and saphenous vein were higher in patients with PAOD than in those without PAOD. A significant step-up of the mature form of AM from the femoral artery to the saphenous vein was observed. Our findings indicate that the plasma AM concentration was elevated in patients with PAOD in proportion to the severity of the disease and associated with vascular inflammation. An increased production of AM in PAOD may play a protective role against advanced atherosclerosis with an inflammatory signature.     

Adrenomedullin as a sensitive marker for coronary and peripheral arterial complications in patients with atherosclerotic risks

Plasma adrenomedullin (AM) levels are elevated in various pathological states including cardiovascular and inflammatory diseases. The present study investigated whether an increased AM level is a marker of vascular complications in patients with atherosclerotic risks. In 114 patients with cardiovascular risks and/or diseases including ischemic heart disease (IHD) and peripheral arterial disease (PAD), plasma AM concentration and other inflammatory markers such as high sensitive C-reactive protein (CRP) and interleukin (IL)-6 were examined. The plasma AM level was not altered by the absence or presence of each of four major risk factors, i.e., hypertension, diabetes mellitus, hyperlipidemia, and smoking and its level was not significantly correlated with blood pressure, plasma glucose, or serum lipid levels. The patients with IHD had a significantly higher concentration of plasma AM than those without IHD. The AM level in subjects with PAD was also increased significantly compared with those without PAD. The plasma AM was strongly correlated with inflammatory parameters such as CRP and IL-6. Among AM, CRP, and IL-6, however, only AM was an independent predictor for both IHD and PAD by multiple logistic regression analysis. Our findings suggest the possibility that plasma AM is a novel sensitive marker for the presence of vascular lesions in patients with atherosclerotic risks.     

Diagnostic evaluation of 2', 5'-oligoadenylate synthetase activities and antibodies against Epstein-Barr virus and Coxiella burnetii in patients with chronic fatigue syndrome in Japan

To investigate the association of viral infections with chronic fatigue syndrome (CFS), we assayed 2', 5'-oligoadenylate synthetase (2-5AS) activities in peripheral blood mononuclear cells from CFS patients in Japan. These patients were diagnosed in two hospitals, H1 and H2, located in different areas of the country. The activities were detected in 19 (86%) and 7 (32%) of each of the 22 patients in H1 and H2, respectively, while they were detected in only four (11%) out of the 38 healthy controls. IFN-alpha was similarly detected in a few CFS patients and healthy controls. We also assayed the antibody titers against Epstein-Barr virus (EBV) and Coxiella burnetii in these patients. The EBV anti-EA-IgG antibodies were detected in two (9%) and seven (32%) of each of the 22 patients in H1 and H2, respectively. Anti-C. burnetii IgG antibodies were detected in six (27%) out of 22 patients in H1 but not in 22 patients in H2, while they were detected in one (11%) of the nine healthy controls. Some CFS patients may be associated with EBV or C. burnetii infection. There were some statistical correlations between the 2-5AS activities and antibody titers of EA-IgG (P < 0.05, Student's t-test) but not to the antibody titers of C. burnetii. The up-regulation of 2-5AS activities suggests immunological dysfunctions with some virus infections in the CFS patients. Our results indicate that 2-5AS activities are useful for a diagnostic marker of CFS and for exploring the complicated pathogenesis of CFS.