Purification and characterization of a novel glutamyl aminopeptidase from chicken meat

A novel glutamyl aminopeptidase (aminopeptidase A, EC 3.4.11.7) was purified from chicken meat by ammonium sulfate fractionation, ethanol fractionation, heat treatment, and successive column chromatographies of DEAE-Sepharose CL-6B and Sephadex G-200. The purified enzyme migrated as a single band on SDS-PAGE. The molecular weight of this enzyme was found to be 55,000 and 550,000 by SDS-PAGE and Sephadex G-200 column chromatographies, respectively. This enzyme hydrolyzed Glu- and Asp-, but not Leu-, Arg-, and Ala-2-naphthylamide (-2NA) at all. The optimum pH and temperature for hydrolysis of Glu-2NA was 7.5. and 70°C, respectively. Reducing agents such as cysteine and dithiothreitol inhibited the activity of this enzyme at concentrations of 1 mM. However, the activation by Ca(2+) and the inhibition by amastatin were not observed.     

Propagation Delay of an RC-Chain With a Ramp Input

In this brief, two simple semi-analytical models which allow the estimation of the propagation delay of an RC-chain with a linear input are presented. The closed-form models can be used to evaluate the propagation delay of wires in modern VLSI and ULSI processes. The two approximations, a continuous function and a piecewise function, exhibit a maximum error lower than 15% at the end of the chain. The models have been validated extensively through circuit simulations. In particular, 1000 different RC-chains have been considered and simulated demonstrating the accuracy of the proposed models with respect to the most widely used Elmore delay metric     

Urinary leukotriene E4 and 11-dehydrothromboxane B2 in patients with aspirin-sensitive asthma

The objective of this study was to define the participation of cysteinyl leukotrienes (LTs) or thromboxane A2 in the pathogenesis of aspirin-sensitive asthma (ASA). Leukotriene E4 (LTE4) and 11-dehydrothromboxane B2 (11DTXB2) values in spot urine were measured in 22 asthmatics with a history of aspirin sensitivity and in 17 without such a history (non-aspirin-sensitive asthma [NASA]) in the outpatient clinic. The urinary LTE4 value was significantly higher in ASA patients than in NASA (340 +/- 47 vs 65 +/- 15 pg/mg.cr, P < 0.001), but there was no significant difference in urinary 11DTXB2 between the two groups (891 +/- 77 vs 657 +/- 90 pg/mg.cr). A high value of LTE4 was not associated with type of asthma, severity of disease, oral prednisolone treatment, sex, or age. A higher value of 11DTXB2 was observed in the atopic type than the nonatopic type in ASA (1086 +/- 111 vs 697 +/- 147 pg/mg.cr, P < 0.05). No correlation was observed between urinary LTE4 and 11DTXB2 in either ASA or NASA. In conclusion, LTs may play an important role in the pathogenesis of ASA, and TXA2 in the pathogenesis of the atopic type in ASA.     

Mechanism of welding fume suppression during AC-pulsed MIG welding of Al-Mg alloys

Welding fume, inevitably generated during arc welding processes, may be a source of occupational pneumoconiosis when persistently inhaled in the long term and accordingly merits serious consideration in occupational hygiene respects. To improve the working environment at welding sites, it is imperative to ensure total air exchange at work sites, local extraction in the vicinity of welding facilities, and the wearing of respiration protection devices in other respects.¹ Currently available preventive measures, however, suffer from a number of drawbacks, such as heavy investments needing to be made in equipment and facilities and operability being obstructed by the wearing of respiration protection devices. Alongside such passive measures, it is desirable to develop welding materials or methods able to suppress welding fume generation at source.     

Phase diagram study of Fe-Zn intermetallics

There are various intermetallic compounds in the Fe-Zn system. The phase diagram of this system is very important for understanding the surface structure of zinc-coated steel; therefore, equilibrium phases and their stable compositions must be known. The bulk samples of the Fe-Zn binary intermetallic compounds were synthesized by lengthy heat treatment for over 7.2×10⁵ s at 450 °C after 1.7×10⁵ s at 850 °C. The X-ray diffraction (XRD) patterns of samples kept for various periods at 450 °C were observed to determine the optimal heat treatment period, and the sample of Θ₁, which requires the longest time to form of all of the Fe-Zn binary intermetallic compounds, was obtained by the 7.2×10⁵ s heat treatment. Chemical composition of the samples was examined and X-ray diffraction was applied to ensure the formation of the intermetallic compounds. The results were in agreement with the literature on the Fe-Zn binary phase diagram.     

Design Procedures for Three-Stage CMOS OTAs With Nested-Miller Compensation

Design procedures for three-stage CMOS operational transconductance amplifiers employing nested-Miller frequency compensation are presented in this paper. After describing the basic methodology on a Class-A topology, some modifications, to increase swing, slew-rate and current drive capability, are subsequently discussed for a Class-AB solution. The approaches developed are simple as they do not introduce unnecessary circuit constraints and yield accurate results. They are hence suited for a pencil-and-paper design, but can be easily integrated into an analog knowledge-based computer-aided design tool. Experimental prototypes, designed in a 0.35-mum technology by following the proposed procedures, were fabricated and tested. Measurement results were found in close agreement with the target specifications     

Degradation factors of a coated impregnated cathode

An M-type cathode has two life-limiting factors: the reduction of impregnants and the degradation of surface coating. The optimum operating temperature and lifetime against the cathode current density are derived for the former. The quantitative temperature dependence on the lifetime of the surface coating is determined by comparing the measured results and theoretical calculations. A comparison of these factors reveals that the lifetime of a coated impregnated cathode is determined by the reduction of impregnants when the cathode is operated at the optimum temperature and with a current density less than 24 A/cm ²     

Sigma 1 receptor subtype is involved in the facilitation of cortical dopaminergic transmission in the rat brain

Our previous studies have shown that three sigma (sigma) receptor ligands, (+)-N-allylnormetazocine ((+)-SKF-10,047), (+/-)-pentazocine and 1,3-di(2-tolyl)guanidine (DTG) differently regulated the dopamine (DA) transmission in the rat brain. In the present study, we attempted to clarify the role of sigma 1 receptor subtype in the regulation of DA transmission using a novel and selective sigma 1 receptor agonist, 1-(3,4-dimethoxyphenethyl)-4(3-phenylpropyl)piperazine dihydrochloride (SA4503) in the rat brain. Acute administration of SA4503 (1.0 mg/kg, p.o.) significantly increased DA and 3,4-dihydroxyphenylacetic acid (DOPAC) levels in the rat frontal cortex, but not in the other six regions, hippocampus, striatum, midbrain, cerebellum, medulla/pons and hypothalamus. The increase of cortical DA level elicited by SA4503 was fully reversed by N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy)phenyl)ethylamine (NE-100) (0.25 mg/kg, p.o.), a putative sigma 1 receptor antagonist. In addition, SA4503 (1.0 mg/kg, p.o.) showed an increase of cortical L-3,4-dihydroxyphenylalanine (L-DOPA) accumulation under the inhibition of dopa decarboxylase activity with m-hydrobenzylhydrazine (NSD-1015), suggesting that SA4503 has activated the cortical DA synthesis rate. These results suggest that the sigma 1 receptor subtype plays an important role in the facilitation of cortical DA transmission. In addition, this phenomenon is partially involved in the augmentation of DA synthesis rate.