Development and characterisation of novel fentanyl-delta opioid receptor antagonist based bivalent ligands

BACKGROUND

Opioid tolerance is a limiting factor in chronic pain. Delta opioid peptide (DOP)(δ) receptor antagonism has been shown to reduce tolerance. Here, the common clinical mu opioid peptide (MOP)(µ) receptor agonist fentanyl has been linked to the DOP antagonist Dmt-Tic (2',6'-dimethyl-L-tyrosyl-1,2,3,4-tetrahydrisoquinoline-3-carboxylic acid) to create new bivalent compounds.

METHODS

Binding affinities of bivalents(#9, #10, #11, #12 and #13) were measured in Chinese hamster ovary (CHO) cells expressing recombinant human MOP, DOP, Kappa opioid peptide (KOP)(κ) and nociceptin/orphanin FQ opioid peptide (NOP) receptors. Functional studies, measuring GTPγ[(35)S] or β-arrestin recruitment, were performed in membranes or whole cells respectively expressing MOP and DOP.

RESULTS

The new bivalents bound to MOP (pKi : #9:7.31; #10:7.58; #11:7.91; #12:7.94; #13:8.03) and DOP (#9:8.03; #10:8.16; #11:8.17; #12:9.67; #13:9.71). In GTPγ[(35)S] functional assays, compounds #9(pEC50:6.74; intrinsic activity:0.05) #10(7.13;0.34) and #11(7.52;0.27) showed weak partial agonist activity at MOP. Compounds #12 and #13, with longer linkers, showed no functional activity at MOP. In antagonist assays at MOP, compounds #9 (pKb:6.87), #10(7.55) #11(7.81) #12(6.91) and #13(7.05) all reversed the effects of fentanyl. At DOP, all compounds showed antagonist affinity (#9:6.85; #10:8.06; #11:8.11; #12:9.42; #13:9.00), reversing the effects of DPDPE ([D-Pen(2,5)]enkephalin). In β-arrestin assays, compared with fentanyl (with response at maximum concentration (RMC):13.62), all compounds showed reduced ability to activate β-arrestin (#9 RMC:1.58; #10:2.72; #11:2.40; #12:1.29; #13:1.58). Compared with fentanyl, the intrinsic activity was: #9:0.12; #10:0.20; #11:0.18; #12:0.09 and #13:0.12.

CONCLUSIONS

The addition of a linker between fentanyl and Dmt-Tic did not alter the ability to bind to MOP and DOP, however a substantial loss in MOP functional activity was apparent. This highlights the difficulty in multifunctional opioid development.

Evolution of the oxygen sensitivity of cytochrome c oxidase subunit 4

Vertebrates possess two paralogs of cytochrome c oxidase (COX) subunit 4: a ubiquitous COX4-1 and a hypoxia-linked COX4-2. Mammalian COX4-2 is thought to have a role in relation to fine-tuning metabolism in low oxygen levels, conferred through both structural differences in the subunit protein structure and regulatory differences in the gene. We sought to elucidate the pervasiveness of this feature across vertebrates. The ratio of COX4-2/4-1 mRNA is generally low in mammals, but this ratio was higher in fish and reptiles, particularly turtles. The COX4-2 gene appeared unresponsive to low oxygen in nonmammalian models (zebrafish, goldfish, tilapia, anoles, and turtles) and fish cell lines. Reporter genes constructed from the amphibian and reptile homologues of the mammalian oxygen-responsive elements and hypoxia-responsive elements did not respond to low oxygen. Unlike the rodent ortholog, the promoter of goldfish COX4-2 did not respond to hypoxia or anoxia. The protein sequences of the COX4-2 peptide showed that the disulfide bridge seen in human and rodent orthologs would be precluded in other mammalian lineages and lower vertebrates, all of which lack the requisite pair of cysteines. The coordinating ligands of the ATP-binding site are largely conserved across mammals and reptiles, but in Xenopus and fish, sequence variations may disrupt the ability of the protein to bind ATP at this site. Collectively, these results suggest that many of the genetic and structural features of COX4-2 that impart responsiveness and benefits in hypoxia may be restricted to the Euarchontoglires lineage that includes primates, lagomorphs, and rodents.

[Dmt1]N/OFQ(1-13)-NH2: a potent nociceptin/orphanin FQ and opioid receptor universal agonist

BACKGROUND AND PURPOSE

Intrathecally (i.t.) administered nociceptin/orphanin FQ (N/OFQ) evokes antinociceptive effects in rodents. Recent studies in monkeys demonstrated that i.t. co-application of N/OFQ and morphine elicits synergistic antinociceptive actions suggesting mixed N/OFQ peptide (NOP) and μ opioid receptor agonists as innovative spinal analgesics. Thus, novel N/OFQ related peptides were synthesized in order to identify and pharmacologically characterize a mixed NOP/ μ opioid receptor agonist.

EXPERIMENTAL APPROACH

The following in vitro assays were used: calcium mobilization in cells expressing the human NOP or classical opioid receptors and chimeric G proteins, receptor and [(35)S]-GTPγS binding, [(35)S]-GTPγS binding in rat spinal cord membranes, guinea pig ileum bioassay. In vivo experiments were performed in monkeys using the tail withdrawal assay.

KEY RESULTS

From calcium mobilization studies [Dmt(1)]N/OFQ(1-13)-NH(2) was selected as the most potent and least selective compound. The mixed NOP/opioid full agonist activity and high affinity of [Dmt(1)]N/OFQ(1-13)-NH(2) was confirmed at human recombinant receptors in receptor binding, calcium mobilization and/or [(35)S]-GTPγS binding studies, at rat spinal cord receptors in [(35)S]-GTPγS binding experiments, and at guinea pig receptors inhibiting neurogenic contractions in the ileum. In vivo in the tail withdrawal assay in monkeys i.t. [Dmt(1) ]N/OFQ(1-13)-NH(2) was able to elicit robust and long-lasting antinociceptive effects.

CONCLUSIONS AND IMPLICATIONS

Collectively, these results demonstrate that [Dmt(1)]N/OFQ(1-13)-NH(2) behaves as NOP/opioid receptor universal agonist and substantiate the suggestion that such mixed ligands are worthy of development as innovative spinal analgesics.

Evaluation of the willingness-to-pay for cancer treatment in Korean metastatic breast cancer patients: a multicenter, cross-sectional study

AIMS

To evaluate the inherent value of breast cancer therapy a willingness-to-pay (WTP) study was conducted in Korean patients with metastatic breast cancer.

METHODS

Patients were prospectively enrolled from four study centers and completed quality of life questionnaires to reflect their status pre-cancer and their current health status. Clinical and socioeconomic data were collected to characterize the population and utilize during modeling. Patients' WTP for breast cancer treatment was assessed using an open-ended question following three rounds of bidding to better hone in on their maximal WTP, starting with one of three randomly assigned start bids. Predictors of patient WTP was evaluated using linear regression models. Associations between WTP and other parameters were evaluated with correlations.

RESULTS

Korean metastatic breast cancer patients were WTP an average of KRW 8 696 329 (US$7555) per month to return to their pre-cancer health state, with those who were recently diagnosed as WTP the most (KRW 12 955 000 [$11 254]). WTP was closely associated with the patient's education level, income, personal financial difficulties, Eastern Cooperative Oncology Group performance status, and their experience of arm symptoms.

CONCLUSION

The results suggest that patients are WTP significant amounts per month for treatment. Breast cancer patients are heavily burdened physically, mentally and financially, and the present study indicated this significant financial burden by disclosing its relationship with WTP. Providing a better understanding of the inherent value of treatment will allow Koreans to better evaluate treatment in the coming era of personalized medicine.

Pharmacological characterization of the bifunctional opioid ligand H-Dmt-Tic-Gly-NH-Bzl (UFP-505)

BACKGROUND

While producing good-quality analgesia, µ-opioid (MOP) receptor activation produces a number of side-effects including tolerance. Simultaneous blockade of δ-opioid (DOP) receptors has been shown to reduce tolerance to morphine. Here, we characterize a prototype bifunctional opioid H-Dmt-Tic-Gly-NH-Bzl (UFP-505).

METHODS

We measured receptor binding affinity in Chinese hamster ovary (CHO) cells expressing recombinant human MOP, DOP, k-opioid (KOP), nociceptin/orphanin (NOP) receptors. For activation, we measured the binding of GTPγ(35)S to membranes from CHO(hMOP), CHO(hDOP), rat cerebrocortex, and rat spinal cord. In addition, we assessed 'end organ' responses in the guinea pig ileum and mouse vas deferens.

RESULTS

UFP-505 bound to CHO(hMOP) and CHO(hDOP) with (binding affinity) pK(i) values of 7.79 and 9.82, respectively. There was a weak interaction at KOP and NOP (pK(i) 6.29 and 5.86). At CHO(hMOP), UFP-505 stimulated GTPγ(35)S binding with potency (pEC(50)) of 6.37 and in CHO(hDOP) reversed the effects of a DOP agonist with affinity (pK(b)) of 9.81 (in agreement with pK(i) at DOP). UFP-505 also stimulated GTPγ(35)S binding in rat cerebrocortex and spinal cord with pEC(50) values of 6.11-6.53. In the guinea pig ileum (MOP-rich preparation), UFP-505 inhibited contractility with pEC(50) of 7.50 and in the vas deferens (DOP-rich preparation) reversed the effects of a DOP agonist with an affinity (pA(2)) of 9.15.

CONCLUSIONS

We have shown in a range of preparations and assays that UFP-505 behaves as a potent MOP agonist and DOP antagonist; a MOP/DOP bifunctional opioid. Further studies in dual expression systems and whole animals with this prototype are warranted.

Search for a new gauge boson in electron-nucleus fixed-target scattering by the APEX experiment

We present a search at the Jefferson Laboratory for new forces mediated by sub-GeV vector bosons with weak coupling α' to electrons. Such a particle A' can be produced in electron-nucleus fixed-target scattering and then decay to an e + e- pair, producing a narrow resonance in the QED trident spectrum. Using APEX test run data, we searched in the mass range 175-250 MeV, found no evidence for an A'→ e+ e- reaction, and set an upper limit of α'/α ~/= 10(-6). Our findings demonstrate that fixed-target searches can explore a new, wide, and important range of masses and couplings for sub-GeV forces.

Common viruses associated with lower pediatric multiple sclerosis risk

BACKGROUND

Because common viruses are encountered during childhood, pediatric multiple sclerosis (MS) offers a unique opportunity to investigate the influence of these viruses on disease susceptibility and the interactions between seroprevalence and select HLA genotypes. We studied seroprevalence for Epstein-Barr virus (EBV), cytomegalovirus (CMV), and herpes simplex virus (HSV) type 1 and HLA-DRB1*1501/1503 status as predictors of pediatric MS.

METHODS

This was a retrospective analysis of prospectively collected demographic, clinical, and biologic data in subjects up to 18 years of age with early MS, control subjects seen at the same regional referral pediatric MS clinics, and additional healthy pediatric control subjects.

RESULTS

Patients with early pediatric MS (n=189) and pediatric control subjects (n=66) were tested. Epstein-Barr nuclear antigen-1 seropositivity was associated with an increased odds of MS (odds ratio [OR] 3.78, 95% confidence interval [CI] 1.52-9.38, p=0.004) in analyses adjusted for age, sex, race, ethnicity, and HLA-DRB1*1501/1503 status. In multivariate analyses including EBV status, a remote infection with CMV (OR 0.27, 95% CI 0.11-0.67, p=0.004) was associated with a lower risk of developing MS. Although a remote infection with HSV-1 was not associated with an increased odds of MS, a strong interaction was found between HSV-1 status and HLA-DRB1 in predicting MS (p<0.001). HSV-1 was associated with an increased risk of MS in those without a DRB1*15 allele (OR 4.11, 95% CI 1.17-14.37, p=0.03), whereas the effect was reversed in those who were DRB1*15-positive (OR 0.07, 95% CI 0.02-0.32, p=0.001).

CONCLUSIONS

These findings suggest that some infections with common viruses may in fact lower MS susceptibility. If this is confirmed, the pathways for risk modification remain to be elucidated.

Structure-Property Relationships in the Toughening of Poly(Methyl Methacrylate) by Sub-Micron Size, Multiple-Layer Particles

Rubber-toughened poly(methyl methacrylate) materials have been prepared by blending poly(methyl methacrylate) with specially-synthesised, refractive index matched particles containing two, three and four radially-alternating rubbery and glassy layers. The paper describes the effects upon mechanical properties of (i) two-, three- and four-layer particle structure and (ii) particle diameter and glassy core size for three-layer particles.

Integration of e-learning resources into a medical school curriculum

BACKGROUND

E-learning has the potential to make important contributions to medical education, but there has been limited study of a blended approach in which the digital resources are introduced alongside traditional teaching methods such as lectures.

METHODS

We describe the successful embedding of an e-learning resource into 3 of the 5 weeks of cardiovascular system teaching for 164 first-year medical students by providing scheduled slots in the timetables. A questionnaire completed by the students at the end of the 5 weeks had a response rate of 66%. Students varied in how they made use of the resource, some systematically working through it and others browsing and studying sections felt to be personally most relevant.

RESULTS

Almost all (96%) rated the e-learning resources as probably or definitely of value: they particularly valued interactive activities, animations, video demonstrations, video clips of experts and self-assessment exercises. Graduate students had a significantly more favourable assessment of the e-learning resources than their undergraduate colleagues, while female students felt the value in supporting existing learning opportunities more strongly than male students.

CONCLUSIONS

It should not be assumed that all students will choose to use an e-learning resource in the same way and instructional design should enable alternative approaches. The sequence in which the e-learning resource is used in relation to the other learning opportunities, such as lectures and PBL group discussions, may be important and merits further consideration. The experiences reported in this study provide encouragement and pointers for others engaged in the integration of e-learning in their curriculum.

Molecular diagnosis in hereditary hemorrhagic telangiectasia: findings in a series tested simultaneously by sequencing and deletion/duplication analysis

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by a unique pattern of telangiectasia and arteriovenous malformations (AVMs). Mutations in one of two genes (ENG and ACVRL1) cause approximately 85% of cases. Genetic testing impacts clinical management because genotype/phenotype correlations exist, and early preventive screening for internal AVMs is recommended in affected individuals prior to the age at which a diagnosis can typically be made based on clinical criteria. We report 383 consecutive cases in which sequencing and large deletion/duplication analysis were performed simultaneously for endoglin (ENG) and activin-like receptor kinase 1 (ACVRL1). We report the first case of mosaicism in an affected individual and 61 novel mutations. We discuss the potential benefits of a diagnostic testing approach for HHT whereby ENG and ACVRL1 are analyzed simultaneously by sequencing and a method which detects large deletion/duplications, rather than by a sequential or reflex testing protocol. We report a case in which a deletion would probably have been missed if large deletion/duplication analysis was performed only if a suspected pathogenic mutation was not first identified by sequencing.

The Childhood Asthma Control Test: retrospective determination and clinical validation of a cut point to identify children with very poorly controlled asthma

BACKGROUND

The Childhood Asthma Control Test (C-ACT) has demonstrated validity in classifying children aged 4 to 11 years as having either "well-controlled" or "not well-controlled" asthma. However, new asthma management guidelines distinguish 3 levels of asthma control.

OBJECTIVE

We sought to determine a second cut point on the C-ACT to identify children with "very poorly controlled" asthma.

METHODS

Binomial logistic regression was performed on data from 671 children. The specialist's rating of control was the criterion measure. Specialists' severity ratings, specialists' assessment of therapy, and FEV(1) percent predicted were used to assess the clinical validity of the cut point.

RESULTS

A cut point of 12 was selected because it correctly classified the highest percentage of participants (66.3%) as having "very poorly controlled" (vs "not well controlled") asthma and demonstrated high specificity (89.8%) and moderate positive predictive value (69.1%). Children scoring 12 or less versus 13 to 19 had lower mean FEV(1) percent predicted (79.8% vs 92.6%, P = .0002) and were more frequently stepped up in therapy (72.9% vs 53.6%, P = .0131) and rated as having severe asthma (13.6% vs 4.5%, P = .0005). One month later, significant differences in C-ACT scores and lung function between these 2 groups persisted. The mean C-ACT score of participants classified as "very poorly controlled" was significantly lower than that of participants classified as "not well-controlled" (17.2 vs 20.3, respectively; P = .0001).

CONCLUSION

A second cut point of 12 or less on the C-ACT identifies children with the lowest level of control, who are at risk for poorer outcomes, and is conceptually consistent with the classification of "very poorly controlled" asthma adopted by asthma management guidelines.