A survey of a functional amino acid of class C beta-lactamase corresponding to Glu166 of class A beta-lactamases

The class C beta-lactamase of Citrobacter freundii GN346 is a typical cephalosporinase comprising 361 amino acids. The aspartic acid at position 217 and glutamic acid at position 219 in this beta-lactamase were, respectively, previously shown not to be the counterpart of Glu166 (ABL166) in class A beta-lactamases, even though sequence alignment of class A and C enzymes strongly suggested this possibility [(1990) FEBS Lett. 264, 211-214; (1990) J. Bacteriol. 172, 4348-4351]. We tried again to assign candidates for the counterpart of Glu166 through sequence alignment based on other criteria, the glutamic acids at positions 195 and 205 in the class C beta-lactamase being selected. To investigate this possibility, these two glutamic acids were changed to glutamine, lysine or alanine, respectively. All the mutant enzymes showed more than 50% of the activity of the wild-type enzyme, indicating that the possibility was ruled out. These results strongly suggested the possibility that the class C beta-lactamase lacks a functional acidic residue corresponding to Glu166 in class A enzymes.     

TAT (time-axis transform) bandwidth compression system of picturesignals

A bandwidth compression system for picture signals called the time-axis transform (TAT) system is introduced. It can be applied to various systems for transmission and recording of picture signals, such as the satellite broadcast system of high-definition television. The TAT compresses the bandwidth by reducing the number of transmitted pixels. The transmitted pixels consist of two kinds: basic pixels and additional pixels. The location of the former is fixed and that of the latter varies from picture to picture to minimize the interpolation error in the reconstructed picture. Thus, the TAT is a hybrid of fixed sampling and variable sampling systems. It compresses the bandwidth of the picture signal to one half or less, keeping high picture quality for both still and moving pictures. The feasibility of the TAT is demonstrated by an experimental system     

Two pyramid machine algorithms for edge detection in noisy binary images

This paper presents a pair of fast algorithms which detect edges in noisy binary images. The algorithms run on a parallel hierarchical cellular array processor called a pyramid machine. Example results are illustrated and the time required by each algorithm is discussed.     

Association of TAP1 and TAP2 with systemic sclerosis in Japanese

Paroxysmal nocturnal haemoglobinuria (PNH) is an acquired clonal stem cell disorder resulting in insufficient and defective haematopoesis associated frequently with aplastic anaemia (AA). A deficiency of the glycosyl phosphatidylinositol (GPI)-anchored complement activation regulatory proteins CD55 and CD59 is responsible for an increased sensitivity of erythrocytes to complement attack leading to chronic intravascular haemolysis with haemoglobinuria. In this study we investigated the effects of complement activation caused by anti-thymocyte globulin (ATG) treatment on the PNH clone in a patient affected with the PNH/AA-syndrome. Fluid phase complement components C3, C4, C6 and terminal complement complex (TCC) were assayed by ELISA. CD55, CD59 and cell-associated TCC were monitored by flow cytometry. ATG treatment resulted in profound systemic complement activation which led to a decrease in the levels of native C3 and C4 to 65% and 40%, respectively, of the original levels on day 5 and of C6 and TCC to 61% and 23%, respectively, on day 10. A return to pre-treatment levels was observed for C3 by day 15, for C6 by day 30 and for C4 by day 90. Flow cytometry revealed that the deficiency in the GPI-anchored protein was restricted to granulocytes, while lymphocytes remained unaffected. Cell-bound TCC increased by 1.67-fold and 2.37-fold on day 5 and day 10, respectively, decreasing to 1.40-fold and 1.30-fold on day 15 and day 30, respectively. The percentage of PNH granulocytes as identified by the absence of the CD55- and CD59-antigens exhibited a temporary decrease from 72% on day 0 to 65% on day 5 and 59% on day 10 and returned thereafter to the original percentage of 70% by day 15 and exceeding this level to 76% on day 30 and 79% on day 90. We report profound activation of the classical pathway of the complement cascade and the terminal complement complex by the globulin leading to a transient decrease of the PNH clone, presumably due to subsequent lysis of the PNH cells devoid of complement regulatory proteins.     

An 18-ns 1-Mbit CMOS SRAM

A 1-Mb (256 K×4 b) CMOS static random-access memory with a high-resistivity load cell was developed with 0.7-μm CMOS process technology. This SRAM achieved a high-speed access of 18 ns. The SRAM uses a three-phase back-bias generator, a bus level-equalizing circuit and a four-stage sense amplifier. A small 4.8×8.5-μm² cell was realized by the use of a triple-polysilicon structure. The grounded second-polysilicon layer increases cell capacitance and suppresses α-particle-induced soft errors. The chip size measures 7.5×12 mm²     

Application of thermogravimetry to loss on drying test and water-content determination of drugs

Thermogravimetry, one of the techniques of thermal analysis, was applied to the quality control of drug raw materials as a "Loss on Drying" or for "Water Content Determination". Twenty two kinds of drugs were selected for the comparison of the applicability of thermogravimetry with that of Loss on Drying Test and/or Water Content Determination by the Karl-Fisher method. In all kinds of drugs, it was ascertained that the results with thermogravimetry agreed well with those obtained by Loss on Drying test and/or Karl-Fisher method. In conclusion, thermogravimetry can be used as a substitute for the Loss on Drying test in cases where drug possess a water bound strongly. Further, thermogravimetry can be utilized for some drugs to which the Karl-Fisher method cannot be applied due to their insolubility in Karl-Fisher reagents.