Surface Properties of Ti65Zr Alloy Modified with TiZr Oxide and Hydroxyapatite

Titanium-zirconium dioxide nanostructures loaded by hydroxyapatite were produced on the surface of Ti65Zr alloy. The alloy was treated by anodization with the subsequent immersion in calcium glycerophosphate (CG) solutions. The resulting surfaces present TiO2-ZrO2 nanotubular (TiZr-NT) structures enriched with hydroxyapatite (HAP). The nanotube texture is expected to enhance the surface's corrosion resistance and promote integration with bone tissue in dental implants. The TiZr-NT structure had a diameter of 73 ± 2.2 nm and a length of 10.1 ± 0.5 μm. The most favorable result for the growth of HAP in Hanks' balanced salt solution (Hanks' BSS) was obtained at a CG concentration of 0.5 g/L. Samples soaked in CG at a concentration of 0.5 g/L demonstrated in a decrease of the contact angles to 25.2°; after 3 days of exposure to Hanks' BSS, the contact angles further reduced to 18.5°. The corrosion studies also showed that the TiZr-NT structure soaked in the CG = 0.5 g/L solution exhibited the best corrosion stability.

Synthesis of Titanium Oxide Nanotubes Loaded with Hydroxyapatite

A simple method of synthesis of TiO2 nanotubes (TiNT) loaded with hydroxyapatite (HAP) is described. Such nanotubes find wide applications in various fields, including biomedicine, solar cells, and drug delivery, due to their bioactivity and potential for osseointegration. The Cp-Ti substrate was anodized at a constant voltage of 40 V, with the subsequent heat treatment at 450 °C. The resulting TiNT had a diameter of 100.3 ± 2.8 nm and a length of 3.5 ± 0.04 μm. The best result of the growth rate of HAP in Hanks' balanced salt solution (Hanks' BSS) was obtained in calcium glycerophosphate (CG = 0.1 g/L) when precipitates formed on the bottom and walls of the nanotubes. Structural properties, surface wettability, corrosion resistance, and growth rate of HAP as an indicator of the bioactivity of the coating have been studied. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), potentiodynamic polarization test (PPC), electrochemical impedance spectroscopy (EIS), and contact angle (CA) measurements were used to characterize HAP-loaded nanotubes (HAP-TiNT). The CA, also serving as an indirect indicator of bioactivity, was 30.4 ± 1.1° for the TiNT not containing HAP. The contact angle value for HAP-TiNT produced in 0.1 g/L CG was 18.2 ± 1.2°, and for HAP-TiNT exposed to Hanks' BSS for 7 days, the CA was 7.2 ± 0.5°. The corrosion studies and measurement of HAP growth rates after a 7-day exposure to Hanks' BSS confirmed the result that TiNT processed in 0.1 g/L of CG exhibited the most significant capacity for HAP formation compared to the other tested samples.

Modeling relationship of pharmacokinetics, in vitro potency, and α4β7 receptor occupancy with intestinal cell trafficking in a gut-homing mouse model of IBD with MORF-057

Objective:

MORF-057 is an orally bioavailable, selective, and potent small molecule inhibitor of α4β7 integrin being developed for inflammatory bowel diseases (IBD) that is currently in phase 1 clinical testing. We have previously presented work that characterized its nonclinical pharmacologic profile. The current study integrates data to generate a pharmacokinetic (PK) and pharmacodynamic (PD) model of MORF-057.

Methods:

To determine in vivo potency, MORF-057 was tested in murine gut homing assays and the PD response was determined relative to the non-protein bound drug in mouse plasma. A cell adhesion assay (CAA) for α4β7 was refined to enable detection of picomolar-level sensitivity. Murine receptor occupancy (RO) assays for α4β7 and α4β1 were established under physiologic conditions, and MORF-057 was evaluated for its potency and selectivity in fresh mouse whole blood. These datasets were used to build and validate predictive models of PD response.

Results:

MORF-057 strongly inhibited the homing of α4β7hi cells to murine gut lymphoid tissues with an IC90 of 7.9 nM. MORF-057 showed high potency in CAA with an IC90 of 8.8 nM. Similarly, RO assays confirmed MORF-057 to be a highly potent inhibitor of α4β7 in mouse whole blood with an IC90 of 20.5 nM and over 1500-fold selectivity vs. α4β1. The predictive models built upon these datasets revealed a strong PK-PD relationship of α4β7 inhibitors in vivo.

Conclusions:

We observed consistently high potency of MORF-057 across multiple assay platforms. Integrated modeling based on these assays, particularly the RO assay, successfully predicted the PD response to MORF-057. These data begin to establish the relationship between PK, target engagement, and PD with MORF-057.

Identification of small-molecule inhibitors of interaction between the BH3 domain and Bcl-xL

To study the role of the BH3 domain in mediating pro-apoptotic and anti-apoptotic activities of Bcl-2 family members, we identified a series of novel small molecules (BH3Is) that inhibit the binding of the Bak BH3 peptide to Bcl-xL. NMR analyses revealed that BH3Is target the BH3-binding pocket of Bcl-xL. Inhibitors specifically block the BH3-domain-mediated heterodimerization between Bcl-2 family members in vitro and in vivo and induce apoptosis. Our results indicate that BH3-dependent heterodimerization is the key function of anti-apoptotic Bcl-2 family members and is required for the maintenance of cellular homeostasis.

Identification of small-molecule inhibitors of interaction between the BH3 domain and Bcl-xL

To study the role of the BH3 domain in mediating pro-apoptotic and anti-apoptotic activities of Bcl-2 family members, we identified a series of novel small molecules (BH3Is) that inhibit the binding of the Bak BH3 peptide to Bcl-xL. NMR analyses revealed that BH3Is target the BH3-binding pocket of Bcl-xL. Inhibitors specifically block the BH3-domain-mediated heterodimerization between Bcl-2 family members in vitro and in vivo and induce apoptosis. Our results indicate that BH3-dependent heterodimerization is the key function of anti-apoptotic Bcl-2 family members and is required for the maintenance of cellular homeostasis.