Structural modification and biological evaluation of Dmt1-DALDA analogues

The highly charged tetrapeptide Dmt-DALDA (Dmt-D-Arg-Phe-Lys-NH2) has been previously identified as a potent μ-opioid receptor agonist1 and serves as a lead compound for the further development of novel therapeutic (peptidic) opioid analgesics. The present work describes structural modifications of the peptide in order to determine the role of the charges, role of N-methylation, and role of conformation. All prepared compounds have been tested for their in vitro affinity and activity (guinea pig ileum GPI and mouse vas deferens MVD assays), their in vitro permeability (caco-2 test) and in vivo tissue distribution, in- and efflux into and out of mouse brain. These experimental data indicate that : i) side-chain charges are not essential for in vitro activity, ii) the guanidine group of D-Arg2 is important for the blood-brain permeability iii) the conformational constraint of the Phe residue by the benzazepine ring results in highly potent compounds, but is not compatible with the Lys side chain, which can best be removed for high potency. A more detailed discussion of the obtained results will be presented. References: 1. Shimoyama, M.; Szeto, H.H.; Schiller, P.W.; Tagaito, Y.; Tokairin, H.; Eun, C.M., Shimoyama N. Pharmacology 2008, 83, 33-37. 2. Zhao, K.; Luo, G., Zhao, G.-M.; Schiller, P.W.; Szeto, H.H. J. Pharmacol. Exp. Ther. 2003, 304, 425-432

Allele-specific miRNA-binding analysis identifies candidate target genes for breast cancer risk

Most breast cancer (BC) risk-associated single-nucleotide polymorphisms (raSNPs) identified in genome-wide association studies (GWAS) are believed to cis-regulate the expression of genes. We hypothesise that cis-regulatory variants contributing to disease risk may be affecting microRNA (miRNA) genes and/or miRNA binding. To test this, we adapted two miRNA-binding prediction algorithms-TargetScan and miRanda-to perform allele-specific queries, and integrated differential allelic expression (DAE) and expression quantitative trait loci (eQTL) data, to query 150 genome-wide significant ( P≤5×10-8 ) raSNPs, plus proxies. We found that no raSNP mapped to a miRNA gene, suggesting that altered miRNA targeting is an unlikely mechanism involved in BC risk. Also, 11.5% (6 out of 52) raSNPs located in 3'-untranslated regions of putative miRNA target genes were predicted to alter miRNA::mRNA (messenger RNA) pair binding stability in five candidate target genes. Of these, we propose RNF115, at locus 1q21.1, as a strong novel target gene associated with BC risk, and reinforce the role of miRNA-mediated cis-regulation at locus 19p13.11. We believe that integrating allele-specific querying in miRNA-binding prediction, and data supporting cis-regulation of expression, improves the identification of candidate target genes in BC risk, as well as in other common cancers and complex diseases.Funding Agency Portuguese Foundation for Science and Technology CRESC ALGARVE 2020 European Union (EU) 303745 Maratona da Saude Award DL 57/2016/CP1361/CT0042 SFRH/BPD/99502/2014 CBMR-UID/BIM/04773/2013 POCI-01-0145-FEDER-022184info:eu-repo/semantics/publishedVersio

Cancer and renal insufficiency results of the BIRMA study

Background: Half of anticancer drugs are predominantly excreted in urine. Dosage adjustment in renal insufficiency (RI) is, therefore, a crucial issue. Moreover, patients with abnormal renal function are at high risk for drug-induced nephrotoxicity. The Belgian Renal Insufficiency and Anticancer Medications (BIRMA) study investigated the prevalence of RI in cancer patients, and the profile/dosing of anticancer drugs prescribed. Methods:Primary end point: to estimate the prevalence of abnormal glomerular filtration rate (GFR; estimated with the abbreviated Modification of Diet in Renal Disease formula) and RI in cancer patient. Secondary end point: to describe the profile of anticancer drugs prescribed (dose reduction/nephrotoxicity). Data were collected for patients presenting at one of the seven Belgian BIRMA centres in March 2006. Results: A total of 1218 patients were included. The prevalence of elevated SCR (1.2 mg per 100 ml) was 14.9%, but 64.0% had a GFR90 ml min 1 per 1.73 m 2. In all, 78.6% of treated patients (n1087) were receiving at least one drug needing dosage adjustment and 78.1% received at least one nephrotoxic drug. In all, 56.5% of RI patients receiving chemotherapy requiring dose reduction in case of RI did not receive dose adjustment. Conclusions: The RI is highly frequent in cancer patients. In all, 80% of the patients receive potentially nephrotoxic drugs and/or for which dosage must be adjusted in RI. Oncologists should check the appropriate dose of chemotherapeutic drugs in relation to renal function before prescribing. © 2010 Cancer Research UK.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

A Phase I study of the angiogenesis inhibitor SU5416 (semaxanib) in solid tumours, incorporating dynamic contrast MR pharmacodynamic end points

SU5416 (Z-3-[(2,4-dimethylpyrrol-5-yl)methylidenyl]-2-indolinone; semaxanib) is a small molecule inhibitor of the vascular endothelial growth factor receptor (VEGFR)2. A Phase I dose escalation study was performed. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) was used as a pharmacodynamic assessment tool. In all, 27 patients were recruited. SU5416 was administered twice weekly by fixed rate intravenous infusion. Patients were treated in sequential cohorts of three patients at 48, 65, 85 110 and 145 mg m−2. A further dose level of 190 mg m−2 after a 2-week lead in period at a lower dose was completed; thereafter, the cohort at 145 mg m−2 was expanded. SU5416 showed linear pharmacokinetics to 145 mg m−2 with a large volume of distribution and rapid clearance. A significant degree of interpatient variability was seen. SU5416 was well tolerated, by definition a maximum-tolerated dose was not defined. No reproducible changes were seen in DCE-MRI end points. Serial assessments of VEGF in a cohort of patients treated at 145 mg m−2 did not show a statistically significant treatment-related change. Parallel assessments of the impact of SU5416 on coagulation profiles in six patients showed a transient effect within the fibrinolytic pathway. Clinical experience showed that patients who had breaks of therapy longer than a week could not have treatment reinitiated at a dose of 190 mg m−2 without unacceptable toxicity. The 145 mg m−2 dose level is thus the recommended dose for future study

Partner notification for sexually transmitted infections in developing countries: a systematic review

<p>Abstract</p> <p>Background</p> <p>The feasibility and acceptability of partner notification (PN) for sexually transmitted infections (STIs) in developing countries was assessed through a comprehensive literature review, to help identify future intervention needs.</p> <p>Methods</p> <p>The Medline, Embase, and Google Scholar databases were searched to identify studies published between January 1995 and December 2007 on STI PN in developing countries. A systematic review of the research extracted information on: (1) willingness of index patients to notify partners; (2) the proportion of partners notified or referred; (3) client-reported barriers in notifying partners; (4) infrastructure barriers in notifying partners; and (5) PN approaches that were evaluated in developing countries.</p> <p>Results</p> <p>Out of 609 screened articles, 39 met our criteria. PN outcome varied widely and was implemented more often for spousal partners than for casual or commercial partners. Reported barriers included sociocultural factors such as stigma, fear of abuse for having an STI, and infrastructural factors related to the limited number of STD clinics, and trained providers and reliable diagnostic methods. Client-oriented counselling was found to be effective in improving partner referral outcomes.</p> <p>Conclusions</p> <p>STD clinics can improve PN with client-oriented counselling, which should help clients to overcome perceived barriers. The authors speculate that well-designed PN interventions to evaluate the impact on STI prevalence and incidence along with cost-effectiveness components will motivate policy makers in developing countries to allocate more resources towards STI management.</p

Analytical characterisation of NOTA-modified somatropins

Chemical modification of biomolecules like the introduction of metal-chelators into proteins can lead to heterogeneous product formation. The nature and extend of the modification is important in interpreting the biological properties of the bioconjugate, given their possible influence on the pharmacokinetics as well as on the binding affinity to the target. The present study describes the synthesis and analytical characterization of somatropin modified on its lysine's e-amino groups with the acylating chelator S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid (p-SCN-Bn-NOTA). Direct separation and identification techniques (i.e. RP-MS and CE-MS) and peptide mapping after trypsin and chymotrypsin digestion demonstrated that the use of higher amounts of p-SCN-Bn-NOTA during synthesis leads to a complex product composition with higher order substitution degrees (i.e. multiple NOTA-moieties per somatropin molecule), as well as the presence of different position isomers. From the nine lysine (Lys) residues in somatropin, Lys-70 was experimentally found to be the modification hotspot under our synthesis conditions (pH. = 9.0). This was supported by the in silico calculated lowest p. Ka value of 8.3 for Lys-70. Based on the crystal structure of somatropin in complex with the extracellular parts of the growth hormone receptor, the Lys-70 residue is positioned outside the binding pockets and will therefore not directly interfere with receptor binding. Gallium chelation by NOTA-somatropin resulted in a 100% complexation. The synthesis of NOTA-somatropin using p-SCN-Bn-NOTA and somatropin under our operational conditions is therefore a suitable synthesis procedure for the production of a target-specific radiopharmaceutical for further investigation toward treatment and visualization of growth hormone-specific cancers. © 2014 Elsevier B.V