Hyaluronidase activity in human pus from which Streptococcus intermedius was isolated

Hyaluronidase (HAase) activity was detected in both a human pus sample and the culture supernatant of the only bacterial isolate from the pus, Streptococcus intermedius, using a zymographic technique. The optimum pH range for HAase activity was similar for both samples. Although the bands showing the strongest HAase activity of these samples differed from each other with respect to molecular size, both samples were equally inhibited by an antiserum raised against HAase of S. intermedius. These results suggest that S. intermedius may produce HAase in vivo as well as in vitro, and that this enzyme and/or its fragments may play an important role in host tissue degradation.     

Biochemical characterization of acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine acetyltransferase in rat spleen microsomes

Acetyl-CoA:1-alkyl-2-lyso-sn-glycero-3-phosphocholine (lyso-PAF) ultrasonic disruption in the presence of 25% glycerol from rat spleen microsomes. About 26% of the enzymatic activity was recovered in the 225,000×g supernatant by this treatment, although the specific activity was slightly decreased compared with the original microsomes. The solubilized enzyme was remarkably susceptible to various kinds of metal ions. Sulfhydryl reagents such as p-chloromercuribenzoate and N-ethyl-maleimide significantly inhibited the enzyme reaction, suggesting that the enzyme is an SH enzyme. Based on the sedimentation pattern in sucrose density centrifugation, the isoelectric point, the kinetic characteristics and the sensitivity to tryptic digestion of microsomes, it appears that acetyl-CoA:lyso-PAF acetyltransferase does not differ from the acetyltransferase responsible for the transfer of acetate from acetyl-CoA to 1-acyl-2-lyso-sn-glycero-3-phosphocholine.     

MR findings in isolated oculomotor nerve palsy associated with infectious mononucleosis caused by Epstein-Barr virus infection

A 20-year-old man presented with fever, bilateral swelling of the cervical and inguinal lymph nodes, and splenomegaly. Later he noted diplopia. CSF was unremarkable. High serum antibodies to Epstein-Barr virus (EBV) were discovered. MRI revealed an abnormal lesion in the right third cranial nerve, which was considered to be the pathological lesion associated with his clinically apparent oculomotor nerve dysfunction.     

Emergence of a unique O3:K6 clone of Vibrio parahaemolyticus in Calcutta, India, and isolation of strains from the same clonal group from Southeast Asian travelers arriving in Japan

Active surveillance of Vibrio parahaemolyticus infection among hospitalized patients in Calcutta, India, was initiated in January 1994. The incidence of cases of V. parahaemolyticus infection suddenly increased in February 1996 and has remained high since then. One hundred thirty-four strains of V. parahaemolyticus isolated from January 1994 to August 1996 were examined for serovar, the presence of the thermostable direct hemolysin gene (tdh) and tdh-related hemolysin genes (trh1 and trh2), production of urease, and antibiogram. Strains of the O3:K6 serovar appeared for the first time in February 1996. The O3:K6 serovar strains accounted for 50 to 80% of the strains isolated during the high-incidence period (February to August 1996). All of the serovar O3:K6 strains carried the tdh gene but not the trh genes and did not produce urease. All of the isolates except two were sensitive to all of the antibiotics tested. These and the results of analysis by an arbitrarily primed PCR method indicated that the O3:K6 serovar strains belong to a unique clone. When the O3:K6 serovar strains, isolated from travelers arriving in Japan from Southeast Asian countries, were compared by the arbitrarily primed PCR method, the strains isolated between 1982 and 1993 were distinct from Calcutta O3:K6 while the strains isolated in 1995 and 1996 were indistinguishable from the Calcutta O3:K6 strains. The results suggest that this unique O3:K6 clone may have become prevalent not only in Calcutta but also in Southeast Asian countries very recently. Not only the O3:K6 strains but also the non-O3:K6, tdh-bearing strains isolated in 1996 produced thermostable direct hemolysin at high levels, and thus the level of hemolysin produced does not appear to have influenced the high incidence of serovar O3:K6 strains.     

Effect of hot-electron injection of high-frequency characteristicsof abrupt In0.52(Ga1-xAlx)0.48As/InGaAs HBT's

The effect of hot-electron injection energy (E_i) into the base on the high-frequency characteristics of In_0/52(Ga_1-xAl_x)_0.48 As/InGaAs abrupt heterojunction bipolar transistors (HBTs) is investigated by changing the composition of the emitter. There exists an optimum E_i at which a maximum current gain cutoff frequency (ft) is obtained. Analysis of hot-electron transport in the base and collector by Monte Carlo simulation is carried out to understand the above phenomenon. The collector transit time (τ_c ) increases with E_i, because electrons with higher energy transfer from the Γ valley into the upper L and X valleys. At first, the base transit time (τ_b ) decreases with E_i at the low E_i region. However, τ_b does not decrease monotically with E_i, because of the nonparabolicity in the energy-band structure of InGaAs. Consequently, there exists a minimum in the sum of τ_b and τ_c , in other words a maximum f_t, at an intermediate value of E_i     

3-D device modeling for SRAM soft-error immunity and tolerance analysis

Soft-error tolerance of static random-access memory (SRAM) devices has been predicted by using three-dimensional (3-D) and time-dependent device simulation in conjunction with circuit simulation. An inverter model developed for 3-D device simulation is described, along with the analysis of the inverters device response as a function of time. The output thus obtained was applied as an input voltage source in circuit simulation of unit SRAM cell and the stability of this bistable circuit is studied on that basis. The effects on soft-error immunity of changes in alpha-particle injection conditions and in load resistance and capacitance are described. The validity of the presented model is examined through comparison of the bit-error-rate dependence on incident angle of alpha particles to that of measured rates. To simulate the angular dependence, we introduce statistical distribution models for alpha-particle energy, position of incidence on the device surface, and angle of incident. Results of device/circuit simulation carried out with many sets of energy, position, and angle are presented. Reasonable agreement between results of simulation and experimental data without the use of adjustment parameters is demonstrated. A map of soft-error tolerance on the CR plane with critical charge Q/sub c/ as a parameter is presented and its derivation explained. An analytic expression for the tolerance is clarified by proposing an equivalent circuit model for the simulation of alpha-particle injection at the output node in an inverter circuit. Inverter modeling is shown to be essential to obtaining SRAM soft-error tolerance to high degrees of accuracy.     

High-efficiency drive due to power factor control of a permanentmagnet synchronous motor

A drive system of a permanent magnet motor without a magnetic position detector is described. Generally, the position data of a magnet is obtained from the terminal voltage of the motor. In the newly developed method, the inverter DC-link current waveform provides the control signal for driving a permanent magnet motor without a detector. Since the power factor of the motor is controlled around 1.0, the motor runs at a higher efficiency than one controlled by the conventional method. Therefore, this control method saves energy. Current pulsation induced by sudden load fluctuations has been studied and its stabilization has been achieved. This paper provides the principle and operation of the new control method, simulated characteristics, and experimental results     

A new self-alignment technology using bridged base electrode forsmall-scaled AlGaAs/GaAs HBT's

The fabrication and characterization of a new self-aligned HBT utilizing bridged base-electrode technology (BBT) are presented. This new technology simplifies the fabrication process and relaxes the limitations in device size scaling, thus decreasing the emitter size to 1 μm×1 μm. In spite of a large junction periphery area ratio, a good current gain of more than 10 is obtained in an HBT with an emitter size of 1 μm×1 μm. A series of fabricated HBTs shows excellent high-speed performance. The highest values of f_T =90 GHz and f_max=63 GHz are obtained in an HBT with an emitter size of 1 μm×5 μm. The realization of HBTs with small emitters and excellent high-frequency characteristics demonstrates the effectiveness of this new technology     

Chemicals influencing maturation, activation, and degeneration of bovine oocytes in culture

The effects of the dibutyryl cyclic adenosine 3',5'-monophosphate, calmodulin antagonist W7, and ovarian glycosaminoglycans on polar body extrusion, "nucleus" formation, and segmentation of bovine oocytes were examined in vitro. Dibutyryl cyclic adenosine 3',5'-monophosphate (100 microM) accelerated the extrusion of first polar body; however, W7 (20 microM) suppressed the formation of the first polar body. Spontaneous "nucleus" formation resembling pronucleus formation in oocytes was accelerated in the presence of dibutyryl cyclic adenosine 3',5'-monophosphate at concentrations of greater than 20 microM. The spontaneous segmentation, which is a degenerative change, was suppressed in the presence of bovine follicular fluid-glycosaminoglycans at concentrations of 250 micrograms/ml or greater. These results may indicate that maturation, activation, and degeneration of bovine oocytes in culture are modulated by dibutyryl cyclic adenosine 3',5'-monophosphate, W7, and ovarian glycosaminoglycans.     

Analysis of electron range versus energy relationship of insulators in low-voltage scanning electron microscopy

A theoretical analysis is made concerning the question of whether or not an insulator's surface is observable without the unstable disturbance due to negative charge-up in the secondary electron mode of a low-voltage scanning electron microscope. Introducing a simple modification into the elementary theory of secondary electron emission from solid materials, the threshold condition as to observability is formulated as a function of the energy E_p and the incident angle ?_p of the primary beam. It is shown that for insulators the material's constant n, which appears in the standard formula of the electron range (R) versus energy (E_p) relationship R Φ E, can be determined through experimental investigations into observability of the surface. Careful consideration is also given to the effectiveness of the present theoretical analysis.