Anti-leukemia effect of perillyl alcohol in Bcr/Abl-transformed cells indirectly inhibits signaling through Mek in a Ras- and Raf-independent fashion.

PURPOSE: Perillyl alcohol (POH) displays preventive and therapeutic activity against a wide variety of tumor models, and it has been suggested that this might be associated with the ability of POH to interfere with Ras prenylation. POH also selectively induces G(1) arrest and apoptosis in Bcr/Abl-transformed hematopoietic cells. Because signaling through Ras is necessary for Bcr/Abl transformation, we examined whether POH induces its anti-leukemia effect by inhibiting Ras signaling. EXPERIMENTAL DESIGN: The ability of POH to inhibit posttranslational farnesylation and signaling from Ras as well as signaling through the Raf-Mek-Erk cascade was examined in Bcr/Abl-transformed and mock-transformed cells and related to the anti-leukemia effect of POH. RESULTS: POH does not affect Ras prenylation or Ras activity, but it blocks signaling downstream of Ras by reversing the state of activation of the Erk kinase, Mek. POH affects Mek activity only when it is added to intact cells. Treatment of either cell lysates or of purified Mek with POH has no effect on Mek activity. Inhibition of the Mek-Erk pathway seems to be related to the POH anti-leukemia effect for the following reasons: (a) the concentration of POH needed to block the Erk pathway, as well the kinetics with which POH inhibits this signaling cascade, both correlate with the anti-leukemia effect of POH; (b) both U0126 (a specific Mek inhibitor) and POH induce similar anti-leukemia effects; and (c) mock-transformed hematopoietic cells are simultaneously resistant to POH anti-leukemia effects and inhibition of the Mek-Erk pathway. CONCLUSION: Blocking Mek is sufficient to induce growth arrest and apoptosis in Bcr/Abl-transformed cells; therefore, POH represents a novel small molecule inhibitor of Mek that might be effective for treating Bcr/Abl leukemias.     

Provider attitudes regarding use of an immunization information system to identify children with asthma for influenza vaccination.

OBJECTIVES: Despite longstanding national guidelines, many children with asthma do not receive annual influenza vaccinations. Information from Medicaid-administrative claims data was integrated into the Michigan Care Improvement Registry (MCIR) to prompt providers regarding influenza vaccination among children with high-risk conditions such as asthma. The attitudes of pediatric primary care providers regarding the implementation of this system were assessed. METHODS: A survey was sent in February 2006 to office-based general pediatricians (n = 300) and family physicians (n = 300) in Michigan. The survey focused on influenza vaccination during the 2005-2006 influenza season and attitudes regarding a reminder system for providers using the MCIR. RESULTS: Overall response rate was 67 percent. MCIR participation was high (91%) among respondents, and most (83%) had MCIR information available to them prior to visits with pediatric patients. Most physicians (75%) considered the MCIR high-risk indicator for influenza vaccination a feature that they would find helpful. Some respondents reported concerns that the reminder system is limited to Medicaid patients only (44%) and regarding the completeness of Medicaid data to identify children with asthma (24%). CONCLUSIONS: Physicians have a positive overall view of a statewide registry-based automated reminder system to assist in identifying children with asthma for influenza vaccination, albeit with specific areas of concern.     

Induction of interferon alpha from human lymphocytes by autologous, dengue virus-infected monocytes

Human monocytes actively replicate dengue virus. To dissect the primary immune responses to dengue virus-infected monocytes (DV-monocytes), we analyzed the interaction between autologous DV-monocytes and the peripheral blood lymphocytes (PBL) of dengue nonimmune donors. Interferon (IFN) activity was detected when PBL were cultured with DV-monocytes. Cell contact between PBL and DV-monocytes was required for IFN production; however, MHC compatibility between PBL and monocytes was not necessary. DV-monocytes fixed with paraformaldehyde or glutaraldehyde, which produced no infectious virus, also induced high levels of IFN from PBL. The ability of DV-monocytes to induce IFN correlated with the appearance of dengue antigens. The PBL that produce IFN were characterized by FACS sorting using monoclonal and polyclonal antibodies. HLA-DR+ and T3- cells produced high titers of IFN, while HLA-DR- and T3+ cells produced very low or undetectable levels of IFN. Moderate titers of IFN were produced by cells contained in B cell fractions (surface immunoglobulin-positive, B1+, and Leu-12+), and cells contained in natural killer cell fractions (Leu-11+ and OKM1+). Therefore, IFN-producing cells are heterogeneous, and the predominant producer cells are characterized as HLA-DR+ and non-T lymphocytes. The IFN produced was characterized by RIA using mAbs to IFN-alpha and IFN-gamma. The IFN-alpha was the predominant IFN produced; in addition, a low level of IFN-gamma was also detected in some experiments. The culture fluids obtained from PBL exposed to autologous DV-monocytes, which contained high IFN activity, completely inhibited dengue virus infection of monocytes. These results suggest that IFN-alpha produced by PBL exposed to DV-monocytes may play an important role in controlling primary dengue virus infection.