On the assignment of high-spin cascades to98Rh and98Pd isotopes

Isotopic assignment of high-spin cascades in⁹⁸Rh and⁹⁸Pd have unambigously been obtained by a suitable combination of the⁹⁶Ru(α, xn yp) and the⁹⁹Ru(d, xn yp) reactions. As a result the band headed by the 841.3 keV line was assigned to⁹⁸Rh and the one headed by the 862.6 keVγ-ray has been found to belong to⁹⁸Pd. In the case of⁹⁸Rh the band is based on the (2⁺) ground state.     

Differential rings and ore extensions: Brown-McCoy rings

We consider here a ringK, a derivationD ofK and the differential polynomial ringR=K[X;D]. The ringK is said to be a Brown-McCoy ring if the prime radical coincides with the Brown-McCoy radical in every homomorphic image ofK. AD-Brown-McCoy ring is defined in a similar way. We prove the following conditions are equivalent: (i)K is aD-Brown-McCoy ring; (ii)R is a Brown-McCoy ring and for every maximal idealM ofR,K/(MνK) is aD-simple ring with 1. In addition, we give some applications and examples on the study of the transfer of the property of being a Brown-McCoy ring betweenK andR. Further, we study the relation between the prime and theD-prime ideals of a differential intermediate extension of a liberal extension. This paper was supported by a fellowship awarded by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Brazil.     

Thermal and structural characterization of poly(ethylene-oxide)/keratin blend films

Blends of poly(ethylene oxide) (PEO) and keratin were prepared with the aim of obtaining bio-compatible materials suitable for film and fibre production. Aqueous keratin solutions, prepared by keratin extraction from wool with urea, m-bisulphite and sodium dodecyl sulphates (SDS), filtration and dialysis, were added with different amounts of PEO and solid films were prepared by casting. The addition of SDS prevents protein aggregation. Morphological, thermal and spectroscopic analysis of the films pointed out that keratin hinders the PEO crystallization process, since a progressive decrease in the size of PEO spherulites is observed and the melting point and the related enthalpy decrease with increasing the keratin content. On the other hand, according to thermal and spectroscopic investigations. PEO seems to interfere with the keratin self-assembling giving the protein a different thermal behaviour.     

First regioselective enzymatic alkoxycarbonylation of primary amines. Synthesis of novel 5'- and 3'-carbamates of pyrimidine 3',5'-diaminonucleoside derivatives including BVDU analogues

The first regioselective enzymatic alkoxycarbonylation of primary amino groups has been achieved in pyrimidine 3',5'-diaminonucleoside derivatives. Thus, Candida antarctica lipase B (CAL-B) catalyzed this reaction with nonactivated homocarbonates allowing the selective synthesis of several N-5' carbamates, including (E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) analogues, with moderate-high yields, whereas immobilized Pseudomonas cepacia lipase (PSL-C) afforded mixtures of alkoxycarbonylated regioisomers. To obtain N-3' carbamates selectively, a short and efficient chemoenzymatic route was used employing some of the N-5'-protected derivatives previously synthesized.     

Base-catalyzed hydroxymethylation of phenol by formaldehyde: Continuous process in a cascade of stirred tank reactors

The kinetic equations relating to the hydroxymethylation stage in base-catalyzed phenol-formaldehyde condensation have been developed as functions of the free phenol concentration. The same kinetic model was applied to the calculation of a continuous process carried out in a cascade of stirred tank reactors. The results obtained in batch and continuous experiments at 70, 80 and 90° were compared with the corresponding calculated values.     

Prolonged exposure of chromaffin cells to nitric oxide down-regulates the activity of soluble guanylyl cyclase and corresponding mRNA and protein levels

Background

Soluble guanylyl cyclase (sGC) is the main receptor for nitric oxide (NO) when the latter is produced at low concentrations. This enzyme exists mainly as a heterodimer consisting of one α and one β subunit and converts GTP to the second intracellular messenger cGMP. In turn, cGMP plays a key role in regulating several physiological processes in the nervous system. The aim of the present study was to explore the effects of a NO donor on sGC activity and its protein and subunit mRNA levels in a neural cell model.

Results

Continuous exposure of bovine adrenal chromaffin cells in culture to the nitric oxide donor, diethylenetriamine NONOate (DETA/NO), resulted in a lower capacity of the cells to synthesize cGMP in response to a subsequent NO stimulus. This effect was not prevented by an increase of intracellular reduced glutathione level. DETA/NO treatment decreased sGC subunit mRNA and β₁ subunit protein levels. Both sGC activity and β₁ subunit levels decreased more rapidly in chromaffin cells exposed to NO than in cells exposed to the protein synthesis inhibitor, cycloheximide, suggesting that NO decreases β₁ subunit stability. The presence of cGMP-dependent protein kinase (PKG) inhibitors effectively prevented the DETA/NO-induced down regulation of sGC subunit mRNA and partially inhibited the reduction in β₁ subunits.

Conclusions

These results suggest that activation of PKG mediates the drop in sGC subunit mRNA levels, and that NO down-regulates sGC activity by decreasing subunit mRNA levels through a cGMP-dependent mechanism, and by reducing β₁ subunit stability.     

Efficient synthesis of novel 1alpha-amino and 3beta-amino analogues of 1alpha,25-dihydroxyvitamin d(3)

Convenient synthetic routes to 1alpha-amino-25-hydroxyvitamin D(3) (3) and 3beta-amino-3-deoxy-1alpha,25-dihydroxyvitamin D(3) (4), novel analogues of vitamin D(3) bearing an amino group at the C-1 or C-3 position, have been developed starting from (S)-(+)-carvone. Construction of the A-ring fragments was accomplished by selective enzymatic hydrolysis of a diester intermediate and introduction of the amino group under Mitsunobu conditions.     

Low energy antiproton annihilation on nuclei

Data obtained in the study of the antiproton interaction on⁴He, Ne and photographic emulsion nuclei are reported. Charged prong multiplicities, branching ratios and reaction cross-section values are given. Some features of¯p annihilation deep inside the nuclear matter are described. Cosmological restrictions deduced from³He production in¯p ⁴He reactions are discussed.Presented at the symposium Mesons and Light Nuclei, Bechyn, Czechoslovakia, May 27–June 1, 1985.