Factor V Leiden and other hypercoagulable state mutations are not associated with osteonecrosis during or after treatment for pediatric malignancy.

OBJECTIVE: Osteonecrosis (ON) is a debilitating complication of cancer treatment in children and is usually associated with systemic steroid therapy. Defects of coagulation may be important in the pathogenesis of ON. This study evaluated the prevalence of factor V Leiden (FVL, 1691G-->A), the most common inherited thrombophilic state, the prothrombin 20210G-->A polymorphism, and the thermolabile methylene tetrahydrofolate reductase (MTHFR, 677C-->T) variant in a group of children in whom ON developed during or after treatment for cancer. STUDY DESIGN: Children in whom ON developed during cancer treatment at St Jude Children's Research Hospital were studied (n = 24). Genomic DNA was isolated, and polymerase chain reaction was performed to identify the FVL, prothrombin 20210, and thermolabile MTHFR mutations. RESULTS: Sixteen of 24 patients had acute lymphoblastic leukemia. The mean age at ON diagnosis was 14.4 +/- 3. 7 years. The mean interval between cancer diagnosis and ON diagnosis was 27 +/- 21 months. Twenty-two patients had received steroids for a mean duration of 24 +/- 15 weeks before having development of ON. No patient had a history of thrombosis. Five (21%) patients had a family history of thrombosis. Genetic analysis revealed 0 (0%) of 24 FVL, 1 (4.5%) of 22 prothrombin 20210, and 3 (13.6%) of 22 thermolabile MTHFR. None of these mutation frequencies was significantly different from our control frequencies or published values. CONCLUSIONS: Although procoagulant abnormalities in general and FVL in particular have been detected in a significant number of patients with ON of the jaw and Legg-Perthes disease, we did not identify an increased prevalence of FVL or other hypercoagulable state mutations in a cohort of children with ON that developed during or after treatment for a variety of cancers.

Expression of the human immunodeficiency virus type 1 primer binding sequence inhibits HIV-1 replication.

Optimal targets for anti-human immunodeficiency virus (HIV) moieties are those regions of the viral genome that are greatly conserved. The primer binding site (PBS) of HIV is an 18-nucleotide sequence complementary to the 3' end of tRNA(Lys3) that serves as the primer for HIV-1 reverse transcription. All HIV-1 isolates analyzed to date contain a PBS complementary to tRNA(Lys3) illustrating the conservation of this sequence. We investigated the activity of a hammerhead ribozyme targeting the PBS of HIV-1. CEMss cells transduced with retroviral vectors containing either the PBS hammerhead ribozyme or its complementary sequence (as a control) in the R region of the vector long terminal repeat (LTR) were challenged with HIV-1NL4-3. Surprisingly >80% inhibition of HIV-1 production was observed with the vector containing the (control) sequence complementary to the PBS ribozyme. We propose that the LTR-driven vector transcript containing 18 nucleotides identical to the HIV-1 PBS may act like an RNA decoy to titrate viral proteins such as reverse transcriptase and nucleocapsid away from genuine viral transcripts, thus compromising virus replication.

Mobilization of CD34+ progenitor cells by granulocyte colony-stimulating factor in human immunodeficiency virus type 1-infected adults.

We conducted a clinical trial to determine the feasibility of growth factor mobilization of CD34+ progenitor cells in human immunodeficiency virus type 1 (HIV-1)-infected individuals. Eight asymptomatic, HIV-1-infected adults (median CD4+ T-cell count, 415 cells/microL), received 480 micrograms/d of granulocyte colony-stimulating factor (G-CSF) for 6 days without evidence of viral activation. Despite concerns that HIV-1 might inhibit hematopoiesis, CD34+ cells were successfully mobilized to the periphery of all donors, independent of the baseline CD4+ T-cell count, and the status of antiretroviral therapy. Leukapheresis was performed on day 6, and yielded a median of 194 x 10(6) CD34+ cells per leukapheresis (n = 7). CD34-enriched cells from the leukapheresis were predominantly myeloid-committed, but between 0.2% and 1.7% were primitive CD34+/CD38- progenitors. A median of 21.7% of the mobilized CD34+ cells were dimly positive for CD4. Consequently, CD34(+)-enriched cells were purified on the cell sorter (mean purity, 97.7% +/- 2.4%; n = 7), and examined for HIV-1 DNA. Purified CD34+ cells from two of seven donors were polymerase chain reaction (PCR)-positive for HIV-1, but only from one of three samples from each donor. We conclude that G-CSF can safely mobilize CD34+ progenitor cells in HIV-1-infected subjects, and that these cells are suitable for consideration in gene-transfer strategies.