Use of TaqMan reverse transcriptase-polymerase chain reaction analysis and serologic testing to eliminate an enzootic infection of mouse hepatitis virus.

Elimination of an enzootic infection of mouse hepatitis virus (MHV) from a large population of genetically engineered mice was accomplished by selecting seropositive, non-infective breeders for a newly restored MHV-free breeding colony. An ELISA was used to test for the presence of MHV-specific antibody, and TaqMan reverse transcriptase-polymerase chain reaction (RT-PCR) analysis was used to detect MHV in the feces. After 10 weeks of intentional exposure, approximately 30% of mice with MHV antibodies continued to shed MHV in the feces. A natural transmission study was conducted to validate that positive fecal RT-PCR results indicated presence of infective virus. Sentinel results from the re-instituted breeding colony indicated that MHV was successfully eliminated by use of RT-PCR analysis for selection of non-infective mice.

Longitudinal in vivo analysis of the region-specific efficacy of parathyroid hormone in a rat cortical defect model.

PTH has been shown to enhance fracture repair; however, exactly when and where PTH acts in this process remains to be elucidated. Therefore, we conducted a longitudinal, region-specific analysis of bone regeneration in mature, osteopenic rats using a cortical defect model. Six-month-old rats were ovariectomized, and allowed to lose bone for 2 months, before being subjected to bilateral 2-mm circular defects in their femoral diaphyses. They were then treated for 5 wk with hPTH1-38 at doses of 0, 3, 10, or 30 microg/kg . d and scanned weekly by in vivo quantitative computed tomography. Quantitative computed tomography analyses showed temporal, dose-dependent increases in mineralization in the defects, intramedullary (IM) spaces, and whole diaphyses at the defect sites. Histomorphometry confirmed PTH stimulation of primarily woven bone in the defects and IM spaces, but not the periosteum. After necropsy, biomechanical testing identified an increase in strength at the highest PTH dose. Serum procollagen type I N-terminal propeptide concentration showed a transient increase due to drilling, but procollagen type I N-terminal propeptide also increased with PTH treatment, whereas tartrate-resistant acid phosphatase unexpectedly decreased. Analyses of lumber vertebra confirmed systemic efficacy of PTH at a nonfracture site. In summary, PTH dose dependently induced new bone formation within defects, at endocortical surfaces, and in IM spaces, resulting in faster and greater bone healing, as well as efficacy at other skeletal sites. The effects of PTH were kinetic, region specific, and most apparent at high doses that may not be entirely clinically relevant; therefore, clinical studies are necessary to clarify the therapeutic utility of PTH in bone healing.

Selective enhancement of multipotential hematopoietic progenitors in vitro and in vivo by IL-20.

In a search for novel growth factors, we discovered that human interleukin-20 (IL-20) enhanced colony formation by CD34+ multipotential progenitors. IL-20 had no effect on erythroid, granulocyte-macrophage, or megakaryocyte progenitors. IL-20 transgenic mice increased the numbers and cell cycling of multipotential but not other progenitors. IL-20 administration to normal mice significantly increased only multipotential progenitor cells, demonstrating that IL-20 significantly influences hematopoiesis, with specificity toward multipotential progenitors. This is the first cytokine with such specificity identified.