Hepatocyte clearance and pharmacokinetics of recombinant factor IX glycosylation variants.

Addition of N-linked glycosylation sites has been shown to increase serum half-life and decrease clearance for proteins such as recombinant erythropoietin (EPO). However, factor IX (FIX) variants with additional N-linked glycans ("HG" variants) that were expressed in HKB11 cells showed increased clearance in rat in vivo pharmacokinetic studies relative to FIX variants with no additional glycans. Variants with multiple additional glycans were the most rapidly cleared. A rat hepatocyte clearance assay was developed to measure intrinsic clearance of these FIX variants in vitro. The rank order of clearance of the variants was the same both in vivo and in the in vitro hepatocyte assay. In the in vitro assay, heparin, galactose, and asialo-orosomucoid inhibited clearance of a FIX HG variant by hepatocytes, and asialo-FIX was rapidly cleared, suggesting roles for the asialoglycoprotein receptor (ASGPR) and cell surface proteoglycans in FIX clearance. Thus the in vitro hepatocyte intrinsic clearance assay is both useful and predictive for identifying rapidly cleared recombinant proteins and for helping to identify receptors involved in clearance of proteins by the liver.

Potent triazolothione inhibitor of heat-shock protein-90.

Heat-shock protein-90 is an attractive target for anticancer drugs, as heat-shock protein-90 blockers such as the ansamycin 17-(allylamino)-17-demethoxygeldanamycin greatly reduce the expression of many signaling molecules that are disregulated in cancer cells and are key drivers of tumor growth and metastasis. While 17-(allylamino)-17-demethoxygeldanamycin has shown promise in clinical trials, this compound class has significant template-related drawbacks. In this paper, we describe a new, potent non-ansamycin small-molecule inhibitor of heat-shock protein-90, BX-2819, containing resorcinol and triazolothione rings. Structural studies demonstrate binding of BX-2819 to the ADP/ATP-binding pocket of heat-shock protein-90. The compound blocked expression of heat-shock protein-90 client proteins in cancer cell lines and inhibited cell growth with a potency similar to 17-(allylamino)-17-demethoxygeldanamycin. In a panel of four cancer cell lines, BX-2819 blocked growth with an average IC(50) value of 32 nM (range of 7-72 nM). Efficacy studies demonstrated that treatment with BX-2819 significantly inhibited the growth of NCI-N87 and HT-29 tumors in nude mice, consistent with pharmacodynamic studies showing inhibition of heat-shock protein-90 client protein expression in tumors for greater than 16 h after dosing. These data support further studies to assess the potential of BX-2819 and related analogs for the treatment of cancer.

The use of newer technologies by New Zealand dentists.

OBJECTIVE: To determine the prevalence and use of newer technologies among New Zealand general dental practitioners (GDPs). DESIGN: Cross-sectional survey of a random sample of GDPs. METHOD: A postal questionnaire was sent to 700 GDPs enrolled on the DCNZ Dentists' Register (response rate 62.8%). RESULTS: Of all the technologies investigated, the digital apex locator (81.4%) and intra-oral camera (49.6%) were the most commonly used. Males and females differed with respect to the use of dental implant systems (41.6% and 24.1% respectively; P<0.05) and intra-oral cameras (53.6% and 39.8% respectively; P<0.05). New Zealand-trained and overseas-trained dentists differed with respect to their use of dental implant systems, with fewer of the latter (21.3%) using them than the former (40.2%). Power bleaching units were more common among more recent graduates. Compared to their city counterparts, dentists in smaller centres appeared to be slower in adopting most forms of newer technology. CONCLUSION: This study (the first of its kind internationally) provides an informative snapshot of New Zealand dentists' use of dental technologies during 2007. Efficiency was the most common reason for using newer technology.

Indolinone based phosphoinositide-dependent kinase-1 (PDK1) inhibitors. Part 1: design, synthesis and biological activity.

HTS screening identified 1 with micromolar inhibitory activity against PDK1. Optimization of 1 afforded 4i (BX-517) which has single-digit nanomolar activity against PDK1 and excellent selectivity against PKA.

Novel small molecule inhibitors of 3-phosphoinositide-dependent kinase-1.

The phosphoinositide 3-kinase/3-phosphoinositide-dependent kinase 1 (PDK1)/Akt signaling pathway plays a key role in cancer cell growth, survival, and tumor angiogenesis and represents a promising target for anticancer drugs. Here, we describe three potent PDK1 inhibitors, BX-795, BX-912, and BX-320 (IC(50) = 11-30 nm) and their initial biological characterization. The inhibitors blocked PDK1/Akt signaling in tumor cells and inhibited the anchorage-dependent growth of a variety of tumor cell lines in culture or induced apoptosis. A number of cancer cell lines with elevated Akt activity were >30-fold more sensitive to growth inhibition by PDK1 inhibitors in soft agar than on tissue culture plastic, consistent with the cell survival function of the PDK1/Akt signaling pathway, which is particularly important for unattached cells. BX-320 inhibited the growth of LOX melanoma tumors in the lungs of nude mice after injection of tumor cells into the tail vein. The effect of BX-320 on cancer cell growth in vitro and in vivo indicates that PDK1 inhibitors may have clinical utility as anticancer agents.