The P element appears to be one of the most recently invaded transposons of D. melanogaster . To study the dynamics and long-term fate of P elements in natural populations of D. melanogaster , 472 isofemale lines newly collected from 27 localities of Japan were examined for the P element-associated characteristics (abilities to induce and repress of P element transposition) and genomic P element composition (size classes and their numbers). There was variation in the P elementrelated phenotypes among local populations, but genomic P composition did not correlate strongly with the phenotype of each line: full-size P and KP elements predominated in their genomes ( FP + KP predominance). Comparison with previous results suggests a stability in the P-M system in local populations over about 15 years. In some populations, phenotypic stability for particularly long times was found: for 30 years or more Q strains predominated in Hikone and Tanushimaru, P or Q strains around Inakadate, and M ' or Q strains around Tozukawa. There was no clear evidence of structural destruction underlying functional variation of P elements during this period. These results suggest that the current evolutionary status of P elements in the gene pool of D. melanogaster is not intermediary stage predicted by the original recent invasion hypothesis, and that several other factors such as the position effect play important roles.

The phosphorylation of extracellular signal-regulated kinase (pERK) in DRG and dorsal horn neurons is induced by the C-fiber electrical stimulation to the peripheral nerve. The present study was designed to investigate the expression and modulation of pERK in the rat dorsal horn neurons produced by repetitive electrical stimulation, and its involvement in the electrophysiological activity of dorsal horn neurons. Electrical stimulation of C-fiber intensity at different frequencies was applied to the sciatic nerve; the stimuli-induced pERK expression and the activity in dorsal horn neurons were studied by immunohistochemistry and extracellular recording, respectively. Electrical stimulation of C-fibers (3 mA) induced pERK expression in dorsal horn neurons in a frequency-dependent manner, indicating that the frequency of electrical stimulation is an important factor which activates the intracellular signal pathway in the spinal cord. To demonstrate the underlying mechanism of this frequency-dependent pERK expression, an NMDA receptor antagonist, MK-801, and a voltage sensitive calcium channel antagonist, nifedipine, were administrated intrathecally before the stimulation. We found that high frequency (0.5 Hz and 10 Hz) but not low frequent (0.05 Hz) stimulus-evoked pERK was partially inhibited by MK-801. Both high and low frequency stimulus-evoked pERK were inhibited by the nifedipine treatment. The extracellular single unit activities were recorded from the laminae I-II and V of the L4-5 dorsal horn, and we found that blockage of the intracellular ERK signal suppressed the wind-up responses in a dose-dependent manner. In contrast, any change in the mechanically evoked responses was not observed following the administration of ERK inhibitor. These observations indicate that ERK activation plays an important role in the induction of the wind-up responses in dorsal horn nociceptive neurons.

The stem-first technique with image-free navigated THA could effectively achieve accurate and consistent control of the CA value and thus is expected to improve the surgical outcome.

We have used the Orthopilot (Aesculap AG, Tuttlingen, Germany) computed tomography (CT)-free navigation system to ensure accurate and reproducible acetabular cup orientation. In this system, cup orientation is assessed with respect to bony configuration as determined by palpation of the anatomical landmarks (the bilateral anterosuperior iliac spines and the upper margin of the pubic symphysis). In this study, intraoperative cup orientation as presented by the OrthoPilot navigation system was compared with the value obtained through postoperative radiological assessment using CT Digital Imaging and Communications in Medicine (DICOM) data and Medical Image Processing, Analysis, and Visualization (MIPAV; National Institutes of Health, US Department of Health and Human Services, Bethesda, Maryland). Intra- and postoperative results obtained from 27 consecutive navigated total hip arthroplasties (THAs) were analyzed. For cup positioning, the desired inclination and anteversion angles were set within the “safe zone” proposed by Lewinnek. In the intraoperative evaluation, the mean inclination angle as determined by the navigation system was 43.5° ± 2.17° (range, 39.9° to 46.6°) after the final implantation. In contrast, the mean inclination angle determined by postoperative calculation using MIPAV was 44.9 ± 3.3° (range, 38.1° to 55.0°). A discrepancy of >5° was observed in only 1 hip. For the anteversion, the mean intra- and postoperative values were 11.1° ± 5.6° (range, 0° to 17.8°) and 13.5° ± 5.9° (range, 5.1° to 21.6°), respectively. Again, a discrepancy of >5° was observed in 1 case. Mean differences between the intra- and postoperative values were 1.9° ± 1.9° and 2.6° ± 1.6° for inclination and anteversion, respectively. A good agreement between the intraoperative values presented by the navigation system and those in the postoperative CT evaluation was observed, and the validity of this navigation system was confirmed.

No abstract