Extraction and retention of technetium-99m-ECD in human brain: dynamic SPECT and oxygen-15-water PET studies

The kinetic behavior of 99mTc-ethyl cysteinate dimer (99mTc-ECD) in the human brain was investigated in six normal volunteers. METHODS: Dynamic SPECT and a three-compartmental model were used to estimate the rate constants of 99mTc-ECD in normal human brain. Extraction fraction (E), retention fraction (R) and permeability surface area product (PS product) of 99mTc-ECD were calculated using the rate constants. Regional cerebral blood flow (rCBF) was measured by PET with 15O-water. RESULTS: The rate constants in the cerebral cortex were estimated as 0.307 +/- 0.021 for K1 (influx constant), 0.201 +/- 0.047 for k2 (backdiffusion rate constant), 0.547 +/- 0.103 for k3 (lipophilic-to-hydrophilic conversion constant) and 0.0028 +/- 0.0012 for k5 (rate constant from lipophilic compartment to blood) at rCBF of 0.509 +/- 0.055 ml/g/min (mean +/- s.d.). The first-pass extraction, retention fraction and PS product were calculated as 0.608 +/- 0.069, 0.734 +/- 0.047 and 0.477 +/- 0.060, respectively. The first-pass extraction of 99mTc-ECD decreased significantly with increases in rCBF. The retention fraction and PS product of 99mTc-ECD did not show significant changes within the normal range of rCBF. The net extraction of 99mTc-ECD calculated from the static SPECT image obtained from 20 to 40 min was 0.358 +/- 0.039 in the cortex. CONCLUSION: Technetium-99m-ECD has a fairly high brain extraction, and its retention fraction and PS product appear to be independent of rCBF in the healthy human brain.     

Mitral valve replacement and coronary artery bypass grafting for postinfarction mitral papillary muscle rupture

A 79-year-old man was admitted to our hospital with heart failure following acute inferior myocardial infarction. An echocardiogram demonstrated severe mitral insufficiency, and coronary arteriography revealed double vesel disease. Following diagnosis of ischemic papillary muscle dysfunction, PTCA was performed, but the mitral insufficiency was not eliminated. Follow-up echocardiography disclosed rupture of the posterior papillary muscle. He underwent surgery on the 30th day after onset of acute myocardial infarction. Partial rupture of the posterior papillary muscle was found at surgery, and mitral valve replacement and single coronary artery bypass to Lcx were performed. His postoperative course was uneventful, and he was discharged on the 46th day after operation.     

Development of elevated temperature structural design guide for Japanese demonstration breeder reactor

Programs to develop the “elevated temperature structural design guide for the demonstration fast breeder reactor” (DDS) in Japan have been conducted since 1987. The DDS is to be developed on the basis of the “elevated temperature structural design guide for class 1 components of prototype fast breeder reactors” (ETSDG), by considering structural and material features of the demonstration fast breeder reactor (DFBR) and incorporating results of the latest R&D. This paper describes the progress of the R& D concept of the DDS, and discusses some typical results of current studies on the DDS.     

Accuracy of beam positioning in TIARA

A beam scanning and target profiling technique that provides precise and easy beam positioning on samples has been established for the light ion and heavy ion microbeam systems in TIARA of JAERI. The beam positioning accuracy in these systems was measured using nuclear track detectors, CR-39's. The beam positioning accuracy and indirect beam positioning technique in the heavy ion microbeam system enabled extremely low current microbeam to hit targeted virgin points in micro-structure semiconductor test samples for study of single event upset (SEU) transient current properties. This paper gives details of the beam scanning and target profiling system, and describes and discusses the experiments by using this system.     

Correlation analysis for forced vibration test of the Haulien large scale seismic test program

The correlation analysis for forced vibration test of a 1/4 scale containment SSI test model constructed in Hualien, Taiwan, was carried out for the case of backfilled foundation. Prior to the correlation analysis, structural property was revised so that calculated fundamental frequency of fixed base condition was adjusted to that derived from test results. Correlation analysis was carried out by ‘Lattice Model’ which was able to estimate soil-structure interaction effects with embedment. The analysis results coincide well with test results and concluded that the mathematical soil-structure interaction model established by the correlation analysis is efficient to estimate a dynamic soil-structure interaction effect with embedment. This mathematical model will be applied as a basic model of simulation analysis for earthquake observation records.     

Effect of Inclusion Size on the Densification of ZnO–Zn7Sb2O12

Two-step densification curves, observed in the constant-rate heating of ZnO–Zn₇Sb₂O₁₂ composites, have been analyzed in correlation with the effect of inclusion particles (Zn₇Sb₂O₁₂). In the presence of these inclusion particles, the ZnO matrix is divided into two regions with different densification characteristics depending on the interaction with the particles. The linear shrinkage at the end of the first step depends on the inclusion size as well as on its volume fraction. The fractional volume of the region influenced by the inclusion particles has been estimated from the densification curve, and the size of the region influenced by an inclusion particle is found to increase with increasing inclusion size.     

Effect of Bismuth of Oxide Content on the Sintering of Zinc Oxide

Densification and microstructure de velopment in Bi₂O₃-doped ZnO have been studied with a special emphasis on the effect of the Bi₂O₃ content. A small amount of Bi₂O₃ in ZnO (0.1 mol%) retarded densification, but the addition of Bi₂O₃ to more than 0.5 mol% promoted densification by the formation of a liquid phase above the eutectic temperature (∼740°C). The liquid phase increased grain-boundary mobility, which was responsible for the formation of intragrain pores and the decrease in the sintered density. The increase in the Bi₂O₃ content increased the probability of the formation of skeleton structure, which reduced the grain growth rate and the sintered density.     

The dilute solution properties of maleic anhydride and maleic acid copolymers. II-unperturbed dimensions and persistence lengths of chains in solution

The light-scattering, osmotic pressure and viscosity data reported in the preceding paper are used to estimate the characteristic ratios and the persistence lengths of poly(maleic anhydride-co-ethyl vinyl ether) (MAn) and poly(maleic acid-co-ethyl vinyl ether) (H-MA) in organic solvents and sodium salt of H-MA (Na-MA) in NaCl aqueous solutions. The characteristics ratios obtained by Stockmayer-Fixman's extrapolation method are as follows: 6.5 for MAn in organic solvents, 9.6 for H-MA in organic solvents, and 10.8 for Na-MA in NaCl aqueous solutions. The persistence lengths of these copolymers were also calculated by applying the wormlike chain model to viscosity data; $\text{～9}\text{A}\text{?}$ for MAn in organic solvents and $\text{～12}\text{A}\text{?}$ for H-MA in organic solvents. For Na-MA in NaCl aqueous solutions, the persistence lengths vary in proportion to the inverse root of the ionic strength C_s (i.e., $\text{C}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>2</mtext>}}{}_{\mathrm{s}}$). The persistence length in the absence of electrostatic interaction (i.e., C_s←∞) is about 10 Å which corresponds to the values of H-MA in organic solvents.