Satellite videoconferencing for healthcare workers: audience characteristics and the importance of continuing education credits.

To assess the opinions of healthcare workers (HCWs) about a satellite videoconference as a means of earning continuing education credit, a telephone survey was conducted in September 1998, 1 month after a live interactive satellite videoconference on antimicrobial use and resistance. There were 180 registered sites in 45 states surveyed, representing 1,589 viewers: 764 nurses (48.1%), 201 physicians (12.6%), and 624 other HCWs (39.3%). Continuing education credit was requested by 51% of nurses, 31% of physicians, and 27% of all other HCWs. Although preferred learning formats varied, 70% of respondents said it was important to offer continuing education credit. Furthermore, 31% of the respondents stated that the videoconference influenced institutional strategies. We concluded that satellite videoconferences are a method to reach audiences around the world efficiently and effectively, provide the latest information, facilitate interaction, and meet some of the demand for continuing education credit for HCWs.

12-O-tetradecanoylphorbol-13-acetate promotion of transgenic mice expressing epidermal-targeted v-fos induces rasHA-activated papillomas and carcinomas without p53 mutation: association of v-fos expression with promotion and tumor autonomy.

Transgenic mice that expressed v-fos exclusively in the epidermis by means of a human keratin K1-based targeting vector (HK1.fos) developed preneoplastic epidermal hyperplasia and hyperkeratosis after long latency and an associated wound promotion stimulus. To assess the requirements for papilloma formation and malignant conversion and determine the sensitivity to a chemical promotion stimulus, HK1.fos mice were promoted with 12-O-tetradecanoylphorbol-13-acetate (TPA). HK1.fos mice were sensitive to TPA promotion but developed papillomas only after long latency (20-30 weeks of promotion) and in relatively few numbers per animal, suggesting the necessity of an additional genetic event prior to overt lesion formation. Consistent with this idea, at 60 weeks, on cessation of TPA promotion, these HK1.fos TPA-papillomas were found to be autonomous, TPA-independent tumors which persisted, grew larger, and converted to malignancy. Analysis of HK1.fos tumor RNA and DNA identified endogenous c-rasHa mutations at codons 12 and 61 in papillomas and carcinomas; however, no p53 tumor suppressor gene mutations were detected. These data indicate that epidermal expression of v-fos induces sensitivity to TPA promotion, but since additional genetic events, such as endogenous c-rasHa activation, appear to be required in tumorigenesis, v-fos may predominantly play a role in the mechanism of promotion to achieve papilloma autonomy and TPA independence. Furthermore, spontaneous malignant conversion in this model does not appear to involve mutations in the p53 tumor suppressor gene.

Inhibition of melanoma growth by adenoviral-mediated HSV thymidine kinase gene transfer in vivo.

To assess the potential of an in vivo, adenovirus-mediated gene therapy approach for the treatment of malignant melanoma, the efficacy of adenovirus-mediated herpes simplex virus thymidine kinase gene (HSV-Ek) transfer and administration of ganciclovir (GCV) was investigated using a nude mouse model. Initially, B16 murine melanoma cells were efficiently transduced in vitro by a recombinant replication-defective adenovirus containing the HSV-tk gene (ADV/RSVtk), and rendered sensitive to cell killing by 10 micrograms/ml GCV. A significant "bystander effect" was observed at low multiplicity of infection in comparison of cell killing to control B16 transduction by adenovirus containing the beta-galactosidase gene (ADV/RSV-beta-gal). In vivo, melanomas established from subcutaneous injection of 4 x 10(5) B16 cells were injected after 14 d with 1 x 10(10) ADV/RSV-tk viral particles. Subsequent treatment for 6 d with GCV resulted in an inhibition of melanoma growth, with an approximately 40-50% reduction in melanoma volume in comparison to controls in repeated experiments. These data demonstrate that adenovirus-mediated gene transfer can function as an efficient delivery system to reduce established tumor burden in vivo. This result may hold significant promise for the development of effective in situ gene therapy for melanoma in humans.

Transgenic mice expressing targeted HPV-18 E6 and E7 oncogenes in the epidermis develop verrucous lesions and spontaneous, rasHa-activated papillomas.

In order to create a transgenic model for human papilloma virus (HPV)-associated carcinogenesis, we have used the regulatory elements of a human keratin K1 (HK1) gene to target the expression of the E6 and E7 oncogenes of HPV-18 exclusively to the epidermis. All murine expressors were viable and lived normal lifetimes; older mice (> 1 year) possessed numerous small lesions with a verrucous (wart-like) histotype. Analysis of newborn epidermis and lesions revealed that the HPV-18 E6/E7 genes were being expressed with a predominance of the E6*/E7 transcript over the full length E6/E7 message. The long latency in lesion appearance may reflect the low level of intact E6 transcripts and the requirement for additional genetic or epigenetic events before production of an overt lesion. In agreement with this proposal, spontaneous papillomas developed that expressed an activated rasHa oncogene (codon 61, A-->T; codon 13, G-->T). All lesions expressed keratin genes K1, K6, and K13 in a fashion characteristic of hyperproliferative or benign tumors with no evidence of malignant conversion. Our results demonstrate that the mouse epidermis represents a relevant in vivo model system to analyze the interaction between HPV and cellular genes in neoplasia.

Epidermal expression of transforming growth factor-alpha in transgenic mice: induction of spontaneous and 12-O-tetradecanoylphorbol-13-acetate-induced papillomas via a mechanism independent of Ha-ras activation or overexpression.

To assess the requirements for papilloma formation in transgenic mice that overexpress transforming growth factor-alpha (TGF-alpha) in the epidermis (HK1.TGF alpha), we tested the sensitivity of HK1.TGF alpha mice to tumor promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA) and analyzed the resultant papillomas for synergic c-Ha-ras activation and overexpression. We observed that HK1.TGF alpha mice were highly sensitive to TPA promotion, exhibiting multiple papillomas as early as the third week of treatment. After 60 wk of promotion, malignant conversion was not observed and tumors regressed upon removal of the TPA promotion stimulus. Most of the TPA-induced papillomas did not have detectable c-Ha-ras mutations at codons 12, 13, or 61, but three papillomas arising after long-term TPA promotion (5-7 mo) exhibited c-Ha-ras activation at codon 61 (A-->T and A-->G). Conversely, spontaneous papillomas arising without TPA promotion, including persisting autonomous papillomas, were all negative for activating c-Ha-ras mutations. Both spontaneous and TPA-induced HK1.TGF alpha papillomas expressed c-Ha-ras message levels similar to those in normal, nontransgenic epidermis or HK1.TGF alpha hyperplastic epidermis. These data demonstrate that TGF-alpha overexpression can be an initiating event for TPA promotion, that papillomatogenesis in HK1.TGF alpha mice proceeds frequently via a pathway independent of Ha-ras activation or overexpression, and, thus, that other events are required for autonomous growth and malignant conversion.

Cooperation between v-fos and v-rasHA induces autonomous papillomas in transgenic epidermis but not malignant conversion.

Transgenic mice have been previously established that express v-rasHa or v-fos exclusively in the epidermis by means of a targeting vector based on the human keratin 1 gene (HK1). Epidermal expression of v-rasHa (HK1.ras) or v-fos (HK1.fos) resulted in hyperplasia, hyperkeratosis, and later, in benign tumors. To assess the potential for oncogene cooperation in vivo mating experiments were performed. Resultant HK1.fos/ras mice exhibited an obvious increase in the severity of neonatal and juvenile preneoplastic phenotypes, together with the immediate onset of tumorigenesis as compared to single oncogene sibling controls. The HK1.fos/ras tumors grew aggressively and often compromised the animals by 10-12 weeks. However, tumors remained benign as determined by histotype and specific keratin markers. These data indicate that v-fos can cooperate with an initiating v-rasHa phenotype to generate autonomous papillomas, but additional events are required for malignant conversion.