Identification of aac(2')-I type b aminoglycoside-modifying enzyme genes in resistant Acinetobacter baumannii.

The aim of this study was to investigate the mechanism underlying the drug resistance of Acinetobacter baumannii toward aminoglycosides. A total of 32 A. baumannii strains were identified by molecular identification and subsequently isolated. The isolates were then amplified by polymerase chain reaction to analyze the 9 aminoglycoside-modifying enzyme genes and 7 16S rRNA methylase genes. Five types of aminoglycoside-modifying enzyme genes and 1 type of 16S rRNA methylase gene were detected in the 32 drug-resistant A. baumannii strains. Positive genes included 7 detection modes, of which the all-6-gene-positive mode aac(2')-Ib+aac(3)-I+aac(6')-Ib+ant(3'')-I+aph(3')-I+armA exhibited the largest number of strains (12, 37.5%). The resistance of A. baumannii against aminoglycosides resulted from the presence of 5 types of aminoglycoside-modifying enzyme genes and the 16S rRNA methylase gene armA. This study is the first to isolate the aac(2')-Ib aminoglycoside-modifying enzyme gene from A. baumannii in a domestic clinical setting.

Anomalous-circular photogalvanic effect in a GaAs/AlGaAs two-dimensional electron gas.

We have studied the circular photogalvanic effect (CPGE) in a GaAs/AlGaAs two-dimensional electron gas excited by near infrared light at room temperature. The anomalous CPGE observed under normal incidence indicates a swirling current which is realized by a radial spin current via the reciprocal spin-Hall effect. The anomalous CPGE exhibits a cubic cosine dependence on the incidence angle, which is discussed in line with the above interpretation.

Anomalous photogalvanic effect of circularly polarized light incident on the two-dimensional electron gas in Al{x}Ga{1-x}N/GaN heterostructures at room temperature.

Under normal incidence of circularly polarized light at room temperature, a charge current with swirly distribution has been observed in the two-dimensional electron gas in Al{0.25}Ga{0.75}N/GaN heterostructures. We believe that this anomalous charge current is produced by a radial spin current via the reciprocal spin Hall effect. It suggests a new way to research the reciprocal spin Hall effect and spin current on the macroscopic scale and at room temperature.

Early pathomorphologic characteristics of the wound track caused by fragments.

Soft-tissue wounds were inflicted on the upper parts of both hind legs of dogs by fragments which were shot with a smooth-bore testing rifle. Three impact velocities were used: "high" (1,500 m/s, six dogs), "middle" (1,000 m/s, eight dogs) and "low" (700 m/s, seven dogs). Debridement and gross examination were carried out 6 hours after wounding. The main conclusions were as follows: 1) Grossly, most of the wound tracks were blind. The primary wound track in the "high"-velocity group looked like a funnel in shape. The wound cavity close to the entrance had the largest diameter. 2) The severity of the tissue damage depended on the impact velocity. The higher the velocity, the larger were the wound cavities, the more tissues damaged, and the wider was the area of tissue damage around the cavity. 3) Based on the gross, light microscopy (LM), and electron microscopy (EM) observations it was found that one of the predominant characteristics of the tissue damage caused by fragments was the irregularity or unevenness. This was especially true in the case of the "high"-velocity group. The distribution of tissue damage seemed to be "jumping" or "mosaic." This probably resulted from the irregularity of the energy delivery from fragments with high velocity and low mass. 4) The differences in morphologic characteristics between wound tracks caused by bullets and those by fragments are discussed.

Pathological changes of gunshot wounds at various intervals after wounding.

Pathological changes of soft tissue wounds inflicted by high-velocity bullets (M 193, 5.56 mm in calibre) and middle-velocity bullets (T 56, 7.62 mm in calibre) were observed 6, 24 and 72 hrs after wounding in 40 dogs. It was noted that the extent of tissue damage would not increase further with the passage of time. Pathological changes of gunshot wounds caused by either high-velocity or middle-velocity bullet were essentially the same. However, in the high-velocity gunshot wounds, there were larger primary wound tracks, more damages to the contusion zone and more marked destructions of ultrastructures in the concussion zone.

Wounding effects of two types of bullets on soft tissue of dogs.

The wounding effects of 5.56 and 7.62 mm calibre bullets, hitting on soft tissues of 130 dogs at various velocities ranging from 513 to 933 m/s have been studied. The injury caused by 5.56 mm bullet was more severe than that caused by 7.62 mm bullet. This is due to the difference in ballistic behavior between the two types of bullets. The wound caused by 5.56 mm bullet was characterized by a trumpet-shaped channel with large defect. The skin around the exit was torn away and its shape was irregular, which, however, occurred only when the tumbling and the breaking of the bullet existed. High-speed X-ray photograph demonstrated that in 5.56 mm bullet group, temporary cavity was much larger and lasted longer. Splashing phenomenon could be seen at the exist and the fragments of the bullet could be found somewhere. Based on the comparisons the amount of absorbed energy, the volume of wound channel, the frequency of developing complex wound and the ratio of dimensions between the entrance and the exit, it proved that the injury caused by 5.56 mm bullet was several to dozens of time as severe as that caused by 7.62 mm bullet. Nevertheless, wound extents by both types of bullet would be similar if the inflicting bullet did not show any significant tumbling, breaking or deformation.