The concentration of angiotensins I and II in blood from the pulmonary artery and left ventricle of man

The concentrations of angiotensin I (AI) and II (AII) were determined by radioimmunoassay in blood from the main pulmonary artery (MPA) and left ventricule (LV) of ten subjects with rheumatic valvular heart disease. The levels of AI were consistently higher in MPA plasma (21.8+/-2.4 pmol/1) than in LV plasma (14.7+/-2.0 pmol/1), paired t, P less than 0.001. The levels of AII were consistently lower in MPA plasma (21.8+/-4.7 pmol/1) than in LV plasma (33.8+/-7.2 pmol/1), paired t, P less than 0.001. The AII antiserum cross-reacted with three metabolites of the hormone, [des-Asp1]angiotensin II, [des-(Asp1, Arg2)angiotensin II [des-(Asp1, Arg2 Val,3]angiotensin II. To characterize the nature of circulating AII immunoreactive material, paper chromatography was used to separate AII from its immunoreactive metabolites. The results showed that 84-100% of the AII immunoreactive material from both MPA and LV plasma chromatographed with the mobility of authentic angiotensin II. The mean pulmonary conversion of endogenous AI was 33+/-4.8% and the net extraction of AII by peripheral tissues was 33+/-4.1%.     

The chemically initiated solid-state polymerization of hexamethylcyclotrisiloxane

The HBr-initiated solid-state polymerization of hexamethylcyclotrisiloxane has been investigated. Up to about 70% conversion, the rate of polymerization is found to be constant but the molecular weight of the polymer formed was observed to increase with conversion. Temperature did not have a marked effect on the polymerization rate as an activation energy of only 2.8 kcal/mole was observed, whereas the rate was found to be exponentially related to the HBr vapor pressure. The HBr and the radiation-initiated solid-state polymerization are compared.     

Clinical and prognostic aspects of adrenocortical neoplasms in childhood

BACKGROUND: A retrospective study of 54 children was undertaken to define the clinical presentation and secretory patterns of adrenal tumors and to evaluate the outcome of surgical resection and medical therapy. PROCEDURES: Different factors were studied in univariate and multivariate analysis by using the Cox proportional hazard model. RESULTS: Median age at diagnosis was 4 years. Boys and girls were affected equally. The disease was revealed by virilization (61%) or by a palpable mass (39%) with a 0.1-5.5 year delay from initial symptoms. At initial examination, we found that 76% of children were virilized. Ninety-four percent of the tested tumors secreted androgens, which were associated with glucocorticoids in 36%. Adrenal tumors in children were smaller than in adults. Half of them measured less than 10 cm. There were recurrences in 40% of children. The survival rate at 5 years was 49%, 70% if resection was microscopically complete and 7% if not (P < 0.001). CONCLUSIONS: In children, rare adrenal tumors have different diagnostic and prognostic characteristics than in adults; however, recurrences remain frequent. The efficacy of chemotherapy, mainly o,p'-DDD (Mitotane), remains to be evaluated in comparative trials.     

Categorisation and priorities for future research on inert matrix fuels: An extended synthesis of the panel discussions

There are three categories of basic fuel cycle needs, which are being addressed by the different types of inert matrix fuel (IMF) concepts currently under development. These are: plutonium burning in existing LWRs, plutonium burning in fast reactors and minor actinide transmutation — corresponding to three distinct timescales for perceived IMF implementation, viz. short, medium and long term, respectively. The current paper, based partly on the two panel discussions organised at the 6^th IMF workshop, presents viewpoints and priorities for each of the three categories of IMF applications, both in terms of the fuel concepts to be pursued and the corresponding R&D requirements.     

A numerical neutronics benchmark study for inert matrix plutonium fuels in uranium dioxide and mixed plutonium-uranium dioxide environments

A numerical benchmark exercise has been under way for comparing the results of different calculational methods/data sets used for the analysis of light water reactor (LWR) configurations employing Pu inert matrix fuels (IMFs). The first phase of the exercise was devoted to infinite arrays of identical IMF cells. The main feature investigated in the second phase has been the influence of the neutron spectra in UO₂ and MOX cores on individual IMF cells. Phase 3 is concerned with the more realistic situation of an IMF assembly surrounded by UO₂ assemblies. Significant discrepancies have been observed for power peaking effects and delayed neutron parameters in Phase 2. In Phase 3, neutron balance differences for the IMF, particularly at EOL, are found to be significantly larger than were observed in Phase 1.