Oxidation of low density lipoprotein by iron or copper at acidic pH

Oxidized low density lipoprotein (LDL) may play a significant role in atherosclerosis. We have investigated the effect of pH on the oxidation of LDL by iron or copper. When LDL was oxidized by iron in the presence of cysteine in either Hanks' balanced salt solution (HBSS) or Ham's F-10 medium, an acidic pH greatly decreased the lag period and increased the rate of formation of hydroperoxides and thiobarbituric acid-reactive substances (TBARS), and increased its uptake by macrophages. There was a dose-dependent increase of LDL oxidation at acidic pH in the presence of increasing concentrations of cysteine. When LDL was oxidized by copper in HBSS, an acidic pH increased the lag phase before the rapid formation of conjugated dienes, hydroperoxides, and TBARS, but increased its uptake by macrophages. Similar results were obtained using Ham's F-10 medium. Cysteine (100 microM) inhibited the modification of LDL by copper in HBSS at both pH 7.4 and 5.5 As atherosclerotic lesions may be acidic, these observations may help to explain why LDL oxidation occurs locally at these sites.     

A stability criterion for asynchronous multirate linear systems

A stability criterion is developed for linear, asynchronous multirate sampled-data systems. Such systems typically include a linear, time variant, continuous-time plant and several unsynchronized digital controllers. The analysis method uses a time-domain approach based on the closed-loop state transition matrix. The result is sufficient stability criterion which gives an objective measure of long-term and short-term stability. A simple example illustrates the method     

Induction and measurement of antisperm antibody responses in vitro

We did a statistical study of 294 strains of Staphylococcus aureus (S. aureus) isolated from skin infections during the period from January of 1989 to December of 1991 in the Department of Dermatology, Kansai Medical University Hospital. We especially examined methicillin-resistant S. aureus (MRSA) from the point of view of incidence, variety of skin infections with MRSA, coagulase type, phase type, and resistance against antimicrobial agents. The frequency of isolation of MRSA has been increasing. In 1991, the proportion of MRSA isolates among all S. aureus strains isolated from skin infections was 41.5%. MRSA was isolated most often from infectious decubitus. Coagulase type II and phage group NT (not typable) MRSA were most frequently isolated. The resistance of MRSA to OFLX and IMP/CS had remarkably increased. Notably, the resistance to MINO was low before 1991.     

Long-term effect of inducible silent ischaemia on left ventricular systolic function

A new method of thin section preparation of III-V semiconductors and multilayers for transmission electron microscopy (TEM) is presented that exhibits considerable advantages over conventional methods such as ion beam milling and jet thinning. GaAs thin films and multilayers of GaAs/In chi Ga1-chi As/GaAs are grown over an etch release layer of AlAs on GaAs substrates by molecular beam epitaxy (MBE). Planar TEM sections prepared by selective etching from these samples show improved ability to image film morphology and dislocation arrangements, and the resulting large thin electron transparent areas facilitate dislocation density measurements and detection of spatial variations. Avoidance of radiation effects and wedge shaping, both common to ion milled samples, allows this method to be used to prepare uniform thickness standards of single layer GaAs films for EDS analysis or lattice imaging.     

Fade duration analysis on earth-space paths at Ku-band in Fukuoka, Japan

Presented are the fade duration dynamics as observed in four close stations. Fade duration statistics derived from the collected received signal during a critical period in the region are presented and analysed. The obtained results are compared with the model release by the ITU-R P.1623 recommendation. Some modifications are then proposed.