RESULTS: Here, we investigated molecular mechanisms of CD437-dependent post-transcriptional regulation of p21WAF1/CIP1 expression. By utilizing MDA-MB-468 HBC cells expressing chimeric rabbit beta-globin-p21WAF1/CIP1 transcripts we mapped multiple CD437-responsive sequences located within positions 1195 to 1795 of the 3'-untranslated region of p21WAF1/CIP1 mRNA. Several cytoplasmic proteins present in MDA-MB-468, MCF-7 HBC as well as HL-60R leukemia cells bound specifically, in vitro, with these CD437-responsive sequences. CD437 treatment of cells resulted in elevated binding of ~85 kD and ~55 kD cytoplasmic proteins with putative CD437-responsive sequences. A 12 nt RNA sequence (5'-UGUGGUGGCACA-3') present within CD437-responsive region of p21WAF1/CIP1 mRNA displayed specific and elevated binding with the above noted proteins. Treatment of cells with ActD or CHX prior to CD437 exposure did not abrogate RNA-protein interactions. However, treatment of cytoplasmic protein extracts with proteinase K or alkaline phosphatase resulted in loss of RNA-protein interactions.

CONCLUSIONS: CD437 regulates cell growth in part by regulating stability of p21WAF1/CIP1 mRNA that involves specific RNA-protein interactions that are phosphorylation-dependent, while not requiring nascent transcription or protein synthesis.

Objective: We utilized a mixed amino acid infusate and an insulin euglycemic clamp technique in the ovine fetus near term, with increases and decreases in circulating amino acid levels of approximately 30 to 40% on average, and determined the impact on cerebral protein synthesis. Methods: Fetal sheep received a 6-hour infusion of Primene(R) 10% (amino acid infusate group) or a co-infusion of insulin and 10% dextrose (insulin/dextrose infusate group) together with a continuous infusion of L-[1-(13)C]-leucine. Measurements were obtained for fetal plasma leucine enrichment at steady-state and brain tissue intracellular free and protein-bound leucine enrichment at necropsy, followed by the determination of cerebral protein fractional synthetic rates (FSR).

Results: Protein FSR for the cerebral cortex averaged approximately 58 and approximately 39%/day when using the intracellular free and plasma enrichment values for the precursor pool measurements, respectively, providing for maximal and minimal FSR values, and with little difference between the amino acid and insulin/dextrose groups, although significantly higher than respective values for the cerebellum.

Conclusion: Accordingly, there was no evidence of a differential effect of increases versus decreases in circulating amino acids on cerebral protein synthesis as studied, which may be attributed to the saturable nature of the blood-brain barrier transporters for amino acids.

METHODS: To test this directly, we engineered OVCA429 human ovarian cancer cells possessing doxycycline-inducible expression of a constitutively-active mutant BMP receptor, ALK3QD, and administered these cells to immunocompromised mice. Further characterization was performed in vitro to address the role of activated BMP signalling on the EOC phenotype, with particular emphasis on epithelial-mesenchymal transition (EMT) and cell adhesion.

RESULTS: Unexpectedly, doxycycline-induced ALK3QD expression in OVCA429 cells reduced tumour implantation on peritoneal surfaces and ascites formation when xenografted into immunocompromised mice by intraperitoneal injection. To determine the potential mechanisms controlling this in vivo observation, we followed with several cell culture experiments. Doxycycline-induced ALK3QD expression enhanced the refractile, spindle-shaped morphology of cultured OVCA429 cells eliciting an EMT-like response. Using in vitro wound healing assays, we observed that ALK3QD-expressing cells migrated with long, cytoplasmic projections extending into the wound space. The phenotypic alterations of ALK3QD-expressing cells correlated with changes in specific gene expression patterns of EMT, including increased Snail and Slug and reduced E-cadherin mRNA expression. In addition, ALK3QD signalling reduced beta1- and beta3-integrin expression, critical molecules involved in ovarian cancer cell adhesion. The combination of reduced E-cadherin and beta-integrin expression correlates directly with the reduced EOC cell cohesion in spheroids and reduced cell adhesion to the extracellular matrix substrates fibronectin and vitronectin that was observed.

CONCLUSIONS: We propose that the key steps of ovarian cancer metastasis, specifically cell cohesion of multicellular aggregates in ascites and cell adhesion for reattachment to secondary sites, may be inhibited by overactive BMP signalling, thereby decreasing the ultimate malignant potential of ovarian cancer in this model system.

DESIGN: Two original questionnaires delivered electronically, one to medical students and the other to recruiters in rural Ontario communities.

SETTING: Ontario, Canada.

PARTICPANTS: All 525 medical students enrolled in the Schulich School of Medicine & Dentistry at the University of Western Ontario in London and physician recruiters in 71 rural communities in Ontario were invited to participate in the study.

MAIN OUTCOME MEASURES: The factors that influence medical students to consider rural practice, strategies used by recruiters, and student perceptions of the ethical appropriateness of both.

RESULTS: The questionnaire was completed by 42.1% of medical students. Lifestyle considerations were an important influence for 93.1% of students. Themes from the qualitative analysis included the ethical appropriateness of financial considerations, economic forces, perceived disadvantages of rural practice, competition between communities, and lack of altruism. Responses were received from recruiters in 43.7% of communities; of those, 92.9% offered financial incentives to attract prospective physicians.

CONCLUSION: Financial and lifestyle considerations are important influences on medical students' choice to practise in rural communities. Most medical students felt incentive programs offered by rural communities were ethically appropriate.

Methods: Nineteen first year medical students voluntarily participated in the ongoing Healthy Sexuality program. Adolescent participants, medical student peer participants and medical students assessed communication comp onents on a 7-point Likert scale at the end of the program. At the year-end OSCE, all first year medical students at the University of Western Ontario were assessed at an adolescent counseling station by a standardized patient (SP) and a physician exa miner. Statistical analysis examined differences between the two groups.

Results: Students who participated in the Healthy Sexuality program did not perform better than their colleagues on the year-end OSCE. A statistically significant correlation between physician examiner and SP evaluations was found (r = 0.62). Adolescent participants communication skills assessments in the Healthy Sexuality Program demonstrated no significant correlation with medical student assessments (self or peer).

Conclusions: Voluntary intervention with adolescents did not result in improved communication skills at the structured year-end examination. Further investigation will be directed towards delineating differences between SP and physician examiner assessments.