Motor control of the jamming avoidance response of Apteronotus leptorhynchus: evolutionary changes of a behavior and its neuronal substrates

The two closely related gymnotiform fishes, Apteronotus and Eigenmannia, share many similar communication and electrolocation behaviors that require modulation of the frequency of their electric organ discharges. The premotor linkages between their electrosensory system and their medullary pacemaker nucleus, which controls the repetition rate of their electric organ discharges, appear to function differently, however. In the context of the jamming avoidance response, Eigenmannia can raise or lower its electric organ discharge frequency from its resting level. A normally quiescent input from the diencephalic pre-pacemaker nucleus can be recruited to raise the electric organ discharge frequency above the resting level. Another normally active input, from the sublemniscal pre-pacemaker nucleus, can be inhibited to lower the electric organ discharge frequency below the resting level (Metzner 1993). In contrast, during a jamming avoidance response, Apteronotus cannot lower its electric organ discharge frequency below the resting level. The sublemniscal pre-pacemaker is normally completely inhibited and release of this inhibition allows the electric organ discharge frequency to rise during the jamming avoidance response. Further inhibition of this nucleus cannot lower the electric organ discharge frequency below the resting level. Lesions of the diencephalic pre-pacemaker do not affect performance of the jamming avoidance response. Thus, in Apteronotus, the sublemniscal pre-pacemaker alone controls the changes of the electric organ discharge frequency during the jamming avoidance response.     

Clinical use of rifampicin during routine reporting of rifampicin susceptibilities: a lesson in selective reporting of antimicrobial susceptibility data

Increased use of rifampicin for in-patients was noted after the laboratory began reporting rifampicin susceptibilities routinely for all Gram-positive bacterial isolates. The appropriateness of rifampicin use was evaluated by chart review for in-patients administered rifampicin during two time periods, before and during routine rifampicin susceptibility reporting, respectively. While rifampicin susceptibility was reported routinely, four patients were subjected to potentially harmful misuse of rifampicin. These findings reconfirm the necessity of interdepartmental consultation and extensive staff education whenever a modification of antimicrobial susceptibility profile reporting is contemplated. Furthermore, they underscore the role of the clinical microbiology laboratory in guiding antimicrobial therapy through limited reporting of susceptibility data.     

Immunolocalization and messenger RNA expression of bone morphogenetic protein-6 in human benign and malignant prostatic tissue

Skeletal metastases are common in advanced prostate cancer, causing considerable morbidity, and they are usually osteoblastic in nature with no clear explanation for this phenomenon. Bone morphogenetic proteins (BMPs) induce bone formation in vivo, and preliminary work showed a possible association between BMPs and prostatic skeletal metastases; differential expression favors BMP-6 as a potential new marker and mediator of osteosclerotic deposit formation. We investigated BMP-6 mRNA and protein expression by in situ hybridization and immunohistochemistry in malignant and benign prostates from 40 men. BMP-6 mRNA expression was detected exclusively in malignant epithelial cells in 20 of 21 patients (95%) with metastases and in 2 of 11 patients (18%) with localized cancer, and it was absent in 8 benign samples. Immunostaining for BMP-6 was predominantly cytoplasmic and was present in all primary tumors with established metastases and in 4 of 11 (36%) organ-confined cancers. In benign prostatic hyperplasia, basal cells and areas of basal cell hyperplasia were positive for BMP-6 by immunohistochemistry. The results suggest a close association between BMP-6 expression in primary malignant prostatic tissue and skeletal metastases. BMP-6 may be responsible, in part, for the osteoblastic changes in metastatic lesions secondary to prostate cancer.     

The effects of postradiation treatment with tamoxifen on local control and cosmetic outcome in the conservatively treated breast

BACKGROUND: The aim of this study was to evaluate the impact on disease recurrence and cosmetic outcome of tamoxifen treatment initiated after breast-conserving therapy (BCT). METHODS: Between 1982 and 1994, 498 women (509 breasts) were treated with BCT in accordance with a highly standardized institutional protocol. Adjuvant tamoxifen was administered to 130 patients (134 breasts), beginning 1-6 weeks after irradiation. The median ages and duration of follow-up for groups who received tamoxifen (TAM+) and no tamoxifen (TAM-) were 62.5 years/56 months and 53 years/60 months, respectively. The members of the TAM+ group were significantly older (P = 0.0001) and had increased incidences of positive axillary lymph nodes or undissected axilla (P = 0.001). There was a significant (P = 0.001) difference between the TAM+ and TAM- groups in the distribution of histopathologic subtypes; this reflected an increased proportion of associated ductal carcinoma in situ in the TAM- group. More extensive regional lymphatic irradiation was administered to the TAM+ group. Chemotherapy was administered to 15% of TAM+ and 28% (P = 0.003) of TAM- patients. There were no significant differences between the groups with respect to tumor size, reexcision, total excised tissue volume, final margin status, total radiation dose, or use of interstitial implant boost. RESULTS: There was no significant difference between the TAM+ and TAM- groups in the overall distribution of cosmetic scores (P = 0.18). The 5-, 7-, and 10-year actuarial local failure rates for TAM+ versus TAM- patients were 0% versus 3.1%, 1.9% versus 5.4%, and 1.9% versus 8.4%, respectively. Multivariate regression analyses of potentially confounding variables revealed no significant associations between tamoxifen and either cosmetic outcome or local failure. CONCLUSIONS: Radiotherapy followed by tamoxifen has no adverse interactive effect on cosmesis, and tamoxifen is associated with a trend toward enhanced 5-year local control probability.