Serum concentration of 20K human growth hormone (20K hGH) measured by a specific enzyme-linked immunosorbent assay. Study Group of 20K hGH

Several GH isoforms have been identified in pituitary and serum, the most abundant of which is the 22K human GH (hGH) isoform. The 20K hGH isoform is produced by alternative splicing of GH messenger ribonucleic acid and comprises approximately 10% of all GH in the pituitary. The physiological role of 20K hGH remains to be determined, partly because of the lack of a simple and specific assay. We have established sensitive enzyme-linked immunosorbent assays (ELISAs) specific to 20K and 22K hGH. To determine whether regulation of 20K hGH secretion is the same as that for 22K hGH, we measured serum concentrations of both species of hGH in normal subjects and patients with a variety of endocrine disorders. The serum levels of 20K hGH after overnight fasting was 118 +/- 178 pg/mL (n = 282) in normal women, significantly higher than that in normal men (64 +/- 170 pg/mL; n = 226). However, there was no difference in the proportion of 20K hGH to 20K plus 22K hGH between men (6.3 +/- 2.6%, mean +/- SD; n = 176) and women (6.3 +/- 2.1%; n = 263). No correlation was detected between the ratio of 20K hGH and age, body height, body weight, or body fat mass in normal subjects. The proportion of 20K hGH was significantly (P < 0.001) higher in patients with active acromegaly (9.2 +/- 2.2%; n = 33) and patients with anorexia nervosa (9.0 +/- 1.9; n = 8), both of which are characterized by chronic elevation of circulating GH levels. The proportion of 20K hGH in successfully treated acromegalic patients did not differ from that in normal subjects, suggesting that GH-producing pituitary tumors secrete a higher proportion of 20K hGH, or that a chronic excess of 22K hGH alters the MCR of 20K hGH. The values in patients with adult GH deficiency, hyperthyroidism, primary hypothyroidism, or GH-independent short stature did not differ from those in normal subjects. The 20K ratio did not change after acute GH provocative tests, such as the insulin tolerance test and the GHRH test. These results suggest that secretion of 20K hGH from the pituitary is under the same control as that of 22K hGH. This new assay may provide a tool for understanding the physiological or pathophysiological role of the 20K hGH isoform.     

Synthesis and properties of poly(phenylacetylene)s having dialkylamino groups

Summary Poly(phenylacetylene)s bearing dialkylamino groups were prepared by the polymerization of p-(N,N-dialkylamino)phenylacetylenes with [Rh(nbd)Cl]₂, and their electrochemical behavior was examined. Rh-catalyzed polymerization of p-(N,N-diethylamino)phenylacetylene (DEAPA) and p-(N,N-di-n-butylamino)phenylacetylene (DBAPA) in toluene in the presence of triethylamine gave good yields of the polymers (86 and 90%, respectively). Poly(DEAPA) was soluble in chloroform and dichloromethane, and poly(DBAPA) dissolved in various solvents such as toluene, THF, dichloromethane and chloroform. Poly(DEAPA) and poly(DBAPA) showed onset temperatures at 248 and 190°C, respectively, and absorptions around 300–400 nm. Electrochemical doping of the polymer films resulted in the shift of the absorptions to a region around 680 nm, which accompanied a color change of the polymer films from green ocher to deep blue. Received: 26 October 1998/Revised version: 6 November 1998/Accepted: 12 November 1998     

Synthesis and polymerization of a self-condensable macromonomer

Summary A novel self-condensable macromonomer that has a polymerizable group at one terminal and an initiator at the other was synthesized by the combination of the conventional macromonomer technique and the SmI₂-induced transformation. Namely, living poly(tetrahydrofuran) [poly(THF)] carrying α-methacryloyl group was prepared by using methacryloyl chloride and silver trifluoromethanesulfonate. The living chain end was capped with sodium 2-bromoisobutyrate, and the sequential reduction of the terminal C-Br bond with SmI₂ gave a terminating samarium enolate. The resulting samarium enolate copolymerized the α-methacryloyl group with methyl methacrylate, giving a hyperbranched block copolymer whose dendritic part consists of two kinds of polymer segments. Received: 4 January 1999/Accepted: 2 February 1999     

Environmental Effects on Microstructural Stability of SiC/SiC Composites

LowZmaterialshavemanyadvantagesinnuclearenvirOInnellts,suchaslessProductionofradioactivewastesduetosubstantiallylowactivation,andhigherconVergentefficiencyduetothecapabilityofhightemp~OPeration.HopkinhasdiscussedSiC-basedmaterialsforfhaionreactorsfor...     

Design and analysis of a brushless motor for ball screw drives

Design and analysis of brushless motors for ball screw drives, such as application-specific electric motors, are presented. Since the motor should be designed as a built-in structure for machining equipment, the motor dimensions are restricted. A new design concept for such applications is presented. Under various combinations of motor dimensions and electrical parameters, the motor performance is simulated using a personal computer, and the optimized parameter combination is selected. Based on the optimized parameters, a prototype motor is constructed to prove the validity of the proposed design procedure. © 1999 Scripta Technica, Electr Eng Jpn, 127(3): 41–52, 1999     

Investigation of the voltage life of mica-alumina composite insulation at high temperatures

Experiments and investigations were carried out on the voltage life of a bar-coil model with a nickel-plated copper conductor covered with mica-alumina composite insulation at a temperature range of 550–850 °C. Diffusion of copper into the insulation layer was observed on the specimens aged for a long period. Insulation with mica paper gave faster diffusion speed and shorter voltage life than insulation with mica flake. The diffusion speed became higher with an increase in temperature. The ac current gradually increased with aging time and increased rapidly just before breakdown. There was the relationship I = aEⁿ (a, n: constants) between ac current I and applied stress E, and n was approximately equal to 1 in the region where thermal unbalance did not occur. Arrhenius's law held in the relationship between ac current and aging time. Therefore, the breakdown mechanism might be that the effective insulation thickness decreased due to copper diffusion into the insulation layer and the ac current increased gradually until thermal breakdown in the last stage. If copper diffuses into the insulation layer, even with no voltage application, the aging time required to decrease the breakdown voltage to a certain level (the voltage life) obeys Arrhenius's law. If the voltage life is dominated by diffusion into the insulation layer, the activation energy for voltage life in the aging test becomes twice that for diffusion, both with and without voltage application. © 1999 Scripta Technica, Electr Eng Jpn, 129(4): 24–31, 1999     

Enhancement of recombinant soluble dengue virus 2 envelope domain III protein production in Escherichia coli trxB and gor double mutant

The dengue virus is currently the most important flavivirus causing human diseases in the tropical and subtropical regions of the world. The envelope protein domain III of dengue virus type 2 (D2EIII), which induces protective and neutralizing antibodies, was expressed as an N-terminal fusion to a hexa-histidine tag in Escherichia coli. The expression of recombinant D2EIII of 103 amino acids in the soluble form can be achieved using suitable host strains, such as Origami, at a low induction temperature of 18 degrees C. The enhanced production of the soluble protein could be attributed to the thioredoxin reductase (trxB) and glutathione reductase (gor) double mutations in the Origami genome. The soluble and refolded D2EIII proteins were recognized by different antibodies including human patient antiserum. The immunization of rats with soluble D2EIII protein elicited the production of antibodies that could recognize the D2EIII protein in the D2EIII precursor protein and in C-terminal truncated dengue envelope protein type 1-4. Thus, this protein production system is suitable for the production of authentic recombinant dengue proteins that may be used in the diagnosis of the dengue virus infection or in vaccine development.     

Room-temperature miscibility gap in LixFePO4

The rechargeable lithium-ion cell is an advanced energy-storage system. However, high cost, safety hazards, and chemical instability prohibit its use in large-scale applications. An alternative cathode material, LiFePO(4), solves these problems, but has a kinetic problem involving strong electron/hole localization. One reason for this is believed to be the limited carrier density in the fixed monovalent Fe(3+)PO(4)/LiFe(2+)PO(4) two-phase electrode reaction in LixFePO4. Here, we provide experimental evidence that LixFePO4, at room temperature, can be described as a mixture of the Fe(3+)/Fe(2+) mixed-valent intermediate LialphaFePO4 and Li1-betaFePO4 phases. Using powder neutron diffraction, the site occupancy numbers for lithium in each phase were refined to be alpha=0.05 and 1-beta=0.89. The corresponding solid solution ranges outside the miscibility gap (0相似文献   

Spin doping of individual molecules by using single-atom manipulation

Being able to control the spin of magnetic molecules at the single-molecule level will make it possible to develop new spin-based nanotechnologies. Gate-field effects and electron and photon excitations have been used to achieve spin switching in molecules. Here, we show that atomic doping of molecules can be used to change the molecular spin. Furthermore, a scanning tunneling microscope was used to place or remove the atomic dopant on the molecule, allowing us to change the molecular spin in a controlled way. Bis(phthalocyaninato)yttrium (YPc(2)) molecules deposited on an Au (111) surface keep their spin-1/2 magnetic moment due to the small molecule-substrate interaction. However, when Cs atoms were carefully placed onto YPc(2) molecules, the spin of the molecule vanished as shown by our conductance measurements and corroborated by the results of density functional theory calculations.