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Fracture repair is a complex process requiring heterotypic interactions between osteogenic cells and immune cells. Recent evidence indicates that macrophages are critically involved in fracture repair. Polarized macrophage populations differentially promote and regulate inflammation in other tissues, but little is known about the various macrophage subtypes and their signaling activities following a bone fracture. The authors hypothesized that classically activated (M1 subtype) and alternatively activated (M2 subtype) macrophages are active during the early repair process to initiate and regulate the inflammatory response. To test our hypothesis, bone marrow was collected from intact femurs (naïve group), contralateral and fractured femurs of mice on days 0, 1, 2, 4, and 7 postfracture. Macrophages were isolated from the bone marrow and macrophage subtypes were identified using flow cytometry with antibodies to F4/80, MHC II, CD86, CD11c, and CD40. Bone marrow cytokine levels were measured using xMAP. Flow cytometry revealed dynamic changes in M1 subtype (F4/80+/MHC II+/CD86+), M2 subtype (F4/80+/MHC II−/CD86−), and dendritic cell (DCs; MHCII+/CD11c+/CD40+) populations following fracture as compared to naïve controls. M1 subtype levels were correlated with IL‐1α, IL‐1ß, IL‐2, IL‐17, Eotaxin, and MCP‐1, while DCs were correlated with IL‐6, G‐CSF, LIF, KC, and VEGF‐A. The results indicate that M1 and M2 subtypes and DCs are recruited to the fracture site early during the repair process and consequently may work in tandem to regulate the inflammatory response required to recruit osteogenic cells needed for later stages of repair.

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A highly practical chromatography-free six-step synthesis of L-734,217 suitable for large scale preparation is described. The key chiral pyridine acid intermediate (R)-1 was prepared in four steps based on a novel chemoselective silyl-mediated conjugate addition of ethyl (2-oxopiperidin-1-yl)acetate to 4-vinylpyridine and a highly productive, recyclable, kinetic resolution with quinine. Subsequent salt breaking/peptide coupling with benzyl 3-(R)-aminobutyrate (2) in a biphasic system, followed by concomitant hydrogenation of the pyridine ring and debenzylation afforded L-734,217 in 20% overall yield (30% with one recyle) from 2-piperidone. The mechanism of this key conjugate addition to 4-vinylpyridine was studied by 13 C NMR.

Losartan, an antihypertensive agent in clinical development, was found to exist in two enantiotropic polymorphic forms, a low-temperature stable form (Form I) and a high-temperature stable form (Form II), the temperatures at which they are stable being related to the transition temperature. X-ray powder diffraction patterns indicated differences in the crystal packing of the two forms. The vibrational data from infrared and Raman spectroscopy suggested a subtle change in molecular conformation and crystal packing in the two forms. Solid-state 13C NMR data of the polymorphs concurred with the vibrational data and indicated that, while the observed line widths reflect no major changes in crystallinity, signal multiplicities and chemical shifts do reflect differences in molecular packing in the respective unit cells. Thus, in the absence of crystallographic data, useful structural information could be derived from spectroscopic results to identify each of the crystalline forms.

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