Determination in plasma of angiotensin-converting enzyme inhibitor by inhibitor-binding assay.

A method of determining a new angiotensin-converting enzyme inhibitor (CS-622) and its active metabolite (RS-5139) in plasma by inhibitor-binding assay has been developed using high-performance liquid chromatography. The assay is based on the principle that the amount of inhibitor bound to the enzyme is inversely related to the amount of hippuric acid liberated on hydrolysis from the artificial substrate (hippuryl-L-histidyl-L-leucine). Plasma was heated at 60 degrees C for 15 min, to inactivate endogenous enzyme, and preincubated with rabbit-lung angiotensin-converting enzyme at 37 degrees C for 3 min. The artificial substrate (5.75 mg/ml in pH 8.3 phosphate buffer containing sodium chloride) was added to the resulting solution, and the mixture was incubated for 30 min. The reaction was terminated by the addition of 2 M hydrochloric acid. The hippuric acid liberated on hydrolysis was extracted with ethyl acetate and determined by reversed-phase chromatography using methylparaben as an internal standard. The total concentration of the inhibitor and its metabolite were determined by this method after de-esterification by rat-plasma esterase. The standard curve was obtained by the regression analysis of log concentration against logit response. The within-day and day-to-day precision were satisfactory. The proposed method is simple, rapid and sensitive enough to determine angiotensin-converting enzyme inhibitor in plasma.     

The canalicular structure of compact bone in the rat at different ages.

Osteocytes communicate through a canalicular system that maintains the vitality and mineral metabolism of bone. Casting the vascular canals and canaliculi of compact bone with methacrylate and viewing them with scanning electron microscopy shows their extent and relationships. Confocal laser scanning microscopy of the same specimen before corrosion establishes the degree of calcification of the different tissue components. These methods were used to compare basal with alveolar compact bone in the rat mandible at different ages. Sections of the mandibular molar region were placed in a methacrylate resin. After polymerization and study with confocal microscopy, the organic matrix was removed. Juvenile rats had large irregular central vascular canals and lacunae that were more concentric in the basal than the alveolar bone. Cast lacunae were round, and the canaliculi from these lacunae were short and thick in both bones. Adult rats had regular concentrically arranged lacunae in the basal bone. Cast lacunae were ellipsoid and flatter in the basal bone than in the alveolar bone. The intercommunicating canaliculi were increased and canaliculi had more branching than the juvenile rats. The aged rats had fewer vascular canals, lacunae, and canaliculi and had osteoporotic changes. The cast lacunae were slender and flat especially in the basal bone. The porosity of the mandible became more pronounced in the alveolar than in the basal bone with aging. The canaliculi of mandibular compact bone thinned and developed extensive branching with adulthood but decreased in size and number with advanced age. Lacunae proceed from the large circular structures of youth to the flat forms of the aged. These studies show that the internal structure of compact bone changes with age and mirrors its functional state.     

Strained layer quantum well semiconductor optical amplifiers: Polarization insensitive amplification

Polarization insensitive optical amplification was demonstrated in newly developed semiconductor optical amplifiers that have strained GalnAsP quantum well structures. We tailored the active region of the quaternary strained layer quantum well structure with a small biaxially tensile strain of 0.2% in the well layers for polarization insensitive operation.     

90-nm process-variation adaptive embedded SRAM modules with power-line-floating write technique

The power consumption of a low-power system-on-a-chip (SoC) has a large impact on the battery life of mobile appliances. General SoCs have large on-chip SRAMs, which consume a large proportion of the whole LSI power. To achieve a low-power SoC, we have developed embedded SRAM modules, which use some low-power SRAM techniques. One technique involves expanding the write margin; another is a power-line-floating write technique, which enables low-voltage write operation. The power-line-floating write technique makes it possible to lower the minimum operating supply voltage by 100 mV. The other techniques involve using a process-variation-adaptive write replica circuit and reducing leakage current. These techniques reduce active power during write operations by 18% and reduce active leakage of the word-line driver by 64%. The prototype SRAM modules achieve 0.8-V operation, and a 512-kb SRAM module achieves 48.4-/spl mu/A active leakage and 7.8-/spl mu/A standby leakage with worst-leakage devices.     

Stability analysis of abnormal multiplication of plankton using parameter identification technique

This paper presents the mathematical approach for the abnormal multiplication of plankton. An abnormal multiplication can be expressed as an unstable problem and the stability of the system is investigated by introducing eigenvalues of a mathematical equation. The stability of the system can be judged by an eigenvalue based on the Lyapunov's stability theory. In this paper, the Arnoldi‐QR method is used to obtain eigenvalues and eigenvectors of the system. The mode superposition method is employed to create spatial distribution needed to analyse the stability. To obtain the objective eigenvalue, the parameter identification technique is employed. The finite element method is used for the discretization in space. Lake Kasumigaura, which is located in Ibaraki Prefecture in Japan, is selected and actual data in 1975, 1976, 1991 and 2000 are used in order to investigate the stability of the specified lake in Japan. Copyright © 2004 John Wiley & Sons, Ltd.     

Anti-inflammatory effect of Zingiber cassumunar Roxb. and its active principles.

The present study was carried out to elucidate the anti-inflammatory effect of the methanol extract obtained from the rhizomes of Zingiber cassumunar Roxb. and its active principles. The methanol extract was partitioned between ether and water, and then the ether-soluble fraction was extracted with n-hexane. The n-hexane-soluble fraction was chromatographed and part of the fraction was rechromatographed by silica gel column. Three compounds were isolated from the n-hexane-soluble fraction and the chemical structures of these compounds were identified as (E)-1-(3,4-dimethoxyphenyl)but-1-ene, (E)-1-(3,4-dimethoxyphenyl)butadiene and zerumbone. The anti-inflammatory activity of these fractions was investigated on carrageenin-induced edema in rats, as well as on acetic acid-induced vascular permeability and writhing symptoms in mice. The methanol extract (p.o.) showed both anti-inflammatory activity and analgesic activity. These activities shifted successively to ether-soluble and n-hexane-soluble fractions and to (E)-1-(3,4-dimethoxyphenyl)but-1-ene. These results suggest that the anti-inflammatory action and analgesic action of Zingiber cassumunar is the result of the (E)-1-(3,4-dimethoxyphenyl)but-1-ene that it contains.     

Dielectric behavior of polyethyleneoxide (polyox)

Ohne Zusammenfassung     

14C-labeling of bromobutide, 2-bromo-3,3-dimethyl-N-(alpha, alpha-dimethylbenzyl)butyramide

Bromobutide, a novel herbicide, was labeled with carbon-14 independently at the carbonyl group and the phenyl ring for use in metabolic studies. 14C-Carbonation of neopentylmagnesium chloride (3) gave 3,3-dimethyl[1-14C]butyric acid (4a) quantitatively. Chlorination of 4a with thionyl chloride followed by alpha-bromination with bromine yielded 2-bromo-3,3-dimethyl[1-14C]-butyryl halide (5a), which was subsequently condensed with alpha, alpha-dimethylbenzylamine (6a) to afford [carbonyl-14C]bromobutide (1a). The overall yield of 1a was 76% from barium [14C]-carbonate (2). Similarly, condensation of alpha, alpha-dimethyl[phenyl-14C]benzylamine (6b), which was prepared from alpha-methyl[phenyl-U-14C]styrene (7) in three steps, with 2-bromo-3,3-dimethylbutyryl halide (5b) gave [phenyl-14C]bromobutide (1b) in 67% yield after purification. The specific activities of 1a and 1b were 1.38 and 0.781 GBq/mmol (37.2 and 21.1 mCi/mmol), respectively.