Structure-activity relationships of the Human Immunodeficiency Virus type 1 maturation inhibitor PF-46396

This work was funded by the University of St Andrews and Society for Applied Microbiology New Lecturer Research Grant awarded to CSA, Wellcome Trust grant (093228) awarded to TKS.HIV-1 maturation inhibitors are a novel class of antiretroviral compounds, which consist of two structurally distinct chemical classes; betulinic acid derivatives and the pyridone-based compound PF-46396. It is currently believed that both classes act by a similar mode of action to generate aberrant non-infectious particles via inhibition of CA-SP1 cleavage during Gag proteolytic processing. In this study we utilized a series of novel analogues, with decreasing similarity to PF-46396, to determine the chemical groups within PF-46396 that contribute to antiviral activity, Gag binding and the relationship between these essential properties. A spectrum of antiviral activity (active, intermediate, inactive) was observed across the analogue series with respect to CA-SP1 cleavage and HIV-1 (NL4-3) replication kinetics in Jurkat T cells. We demonstrate that selected inactive analogues are incorporated into WT immature particles and that one inactive analogue is capable of interfering with PF-46396 inhibition of CA-SP1 cleavage. Mutations that confer PF-46396 resistance can impose a defective phenotype on HIV-1 that can be rescued in a compound-dependent manner. Some inactive analogues retained the capacity to rescue PF-46396-dependent mutants (SP1-A3V, SP1-A3T, CA-P157S), implying that they can also interact with mutant Gag. The structure-activity relationships observed in this study demonstrate that (i) the tert-butyl group is essential for antiviral activity, but not an absolute requirement for Gag binding, (ii) the trifluromethyl group is optimal but not essential for antiviral activity and (iii) the 2-aminoindan group is important for antiviral activity and Gag binding but not essential as its replacement is tolerated.Publisher PDFPeer reviewe

Supramolecular amplification of amyloid self-assembly by iodination

Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents

Supramolecular amplification of amyloid self-assembly by iodination

Amyloid supramolecular assemblies have found widespread exploitation as ordered nanomaterials in a range of applications from materials science to biotechnology. New strategies are, however, required for understanding and promoting mature fibril formation from simple monomer motifs through easy and scalable processes. Noncovalent interactions are key to forming and holding the amyloid structure together. On the other hand, the halogen bond has never been used purposefully to achieve control over amyloid self-assembly. Here we show that single atom replacement of hydrogen with iodine, a halogen-bond donor, in the human calcitonin-derived amyloidogenic fragment DFNKF results in a super-gelator peptide, which forms a strong and shape-persistent hydrogel at 30-fold lower concentration than the wild-type pentapeptide. This is remarkable for such a modest perturbation in structure. Iodination of aromatic amino acids may thus develop as a general strategy for the design of new hydrogels from unprotected peptides and without using organic solvents

alpha-cluster structure of 18Ne

In this work we study alpha-clustering in 18Ne and compare it with what is known about clustering in the mirror nucleus 18O. The excitation function of 18Ne was measured in inverse kinematics from the resonant elastic scattering reaction of 14O on 4He in the excitation energy range from 8 to 17 MeV, using the active target TexAT. The analysis was performed using a multi-channel R-matrix approach. Detailed spectroscopic information is obtained from the R-matrix analysis: excitation energy of the states, spin and parity as well as partial alpha and total widths. This information is compared with theoretical models and previous data. Clustering structures appear to be robust and mostly isospin symmetric. A good correspondence was found between the levels in 18O and 18Ne. We carried out an extensive shell model analysis of the experimental data. This comparison suggests that strongly clustered states remain organized in relation to the corresponding reaction channel identified by the number of nodes in the relative alpha plus core wave function. The agreement between theory and experiment is very good and especially useful when it comes to understanding the clustering strength distribution. The comparison of the experimental data with theory shows that certain states, especially at high excitation energies, are significantly more clustered than predicted. This indicates that the structure of these states is collective and is aligned towards the corresponding alpha reaction channel

Cabazitaxel versus docetaxel for treatment of metastatic castrate refractory prostate cancer

Objectives To assess cabazitaxel versus docetaxel re-challenge for the treatment of metastatic castrate refractory prostate cancer (CRPC) patients previously treated with docetaxel at inception of primary hormone therapy. Patients and Methods The CANTATA trial was a prospective, two-arm, open-label, phase II study conducted in eight UK centres. Patients over the age of 18, with histologically proven, metastatic prostate cancer who had been previously treated with up to 6 cycles of docetaxel as part of the STAMPEDE trial (or treated with the same drug outside of the trial at primary diagnosis) and had a performance status (PS) of 0–2, were eligible. Patients who progressed during primary treatment with docetaxel or had received prior systemic chemotherapy were excluded. Cabazitaxel (25 mg/m2) or docetaxel (75 mg/m2) was administered via intravenous infusion every 3 weeks with oral prednisolone (10 mg) for up to 10 cycles, until disease progression, death or unacceptable toxicity. The primary outcome was clinical progression-free survival (PFS) as defined by either date of pain progression, date of a cancer-related skeletal-related event, or date of death from any cause. Analyses were by intention to treat. EudraCT number: 2012-003835-40 Results Between 7 March 2013 and 4 January 2016, 15 patients with a median age of 70 years (range 54–76) were recruited; seven received cabazitaxel, eight docetaxel. The study was halted due to slow accrual. The median clinical PFS time in the cabazitaxel group was 6.2 months compared with 8.4 for the docetaxel group (95% confidence intervals were not reached due to the small number of patients). A total of 13 serious adverse events were reported. Conclusion Due to the low number of patients recruited, meaningful comparisons could not be made. However, toxicity was in line with known outcomes for these agents, demonstrating it is feasible and safe to deliver chemotherapy to men relapsing with CRPC after upfront chemotherapy