Maureen Gc Gillan

SPECTRUM OF THE μ‐, δ‐ AND κ‐BINDING SITES IN HOMOGENATES OF RAT BRAIN

1 In homogenates of rat brain, the binding characteristics of tritiated opiates and opioid peptides were examined and the relative capacities of μ‐, δ‐ and κ‐binding sites of the opiate receptor determined by saturation analysis. 2 In competition experiments, binding of the selective μ‐ligand [3H]‐[d‐Ala2,MePhe4,Gly‐ol5]enkephalin at the μ‐site was displaced by [d‐Ala2,d‐Leu5]enkephalin with rather low affinity (KI = 12.6 nm) and more readily by the ketazocine‐like compounds (−)‐ethylketazocine (KI = 3.1 nm) and (−)‐bremazocine (KI = 0.32 nm), which also displaced the binding of [3H]‐[d‐Ala2,d‐Leu5]enkephalin from the δ‐site. In contrast, the binding to the κ‐site was easily displaced by ethylketazocine (1.0 nm) and bremazocine (0.37 nm) but not by the μ‐ligand [d‐Ala2,MePhe4,Gly‐ol5]enkephalin (KI = 2000–3000 nm) or the δ‐ligand [d‐Ala2,d‐Leu5]enkephalin (KI > 20,000 nm). 3 The dissociation equilibrium constant (KD) and the binding capacity (pmol/g) of the μ‐binding site were determined with the selective μ‐ligand [3H]‐[d‐Ala2,MePhe4,Gly‐ol5]enkephalin. For the δ‐site, [3H]‐[d‐Ala2,d‐Leu5]enkephalin was used in the presence of unlabelled [d‐Ala2,MePhe4,Gly‐ol5]enkephalin in order to suppress cross‐reactivity to the μ‐binding site. For the estimation of κ‐binding, [3H]‐(±)‐ethylketazocine or [3H]‐(−)‐bremazocine were used in the presence of unlabelled μ‐ and δ‐ligands for the suppression of cross‐reactivities to the μ‐ and δ‐binding sites. 4 In rat brain the capacity of the μ‐binding site was 7.3 pmol/g brain, that of the δ‐binding site 6.7 pmol/g brain and that of the κ‐binding site 2.0 pmol/g brain. Thus, the κ‐binding site had the lowest value whereas in the guinea‐pig brain the capacity of the μ‐binding site was lower than that of the δ‐ or κ‐binding site.

Single Reading with Computer-Aided Detection for Screening Mammography

BACKGROUND The sensitivity of screening mammography for the detection of small breast cancers is higher when the mammogram is read by two readers rather than by a single reader. We conducted a trial to determine whether the performance of a single reader using a computer-aided detection system would match the performance achieved by two readers. METHODS The trial was designed as an equivalence trial, with matched-pair comparisons between the cancer-detection rates achieved by single reading with computer-aided detection and those achieved by double reading. We randomly assigned 31,057 women undergoing routine screening by film mammography at three centers in England to double reading, single reading with computer-aided detection, or both double reading and single reading with computer-aided detection, at a ratio of 1:1:28. The primary outcome measures were the proportion of cancers detected according to regimen and the recall rates within the group receiving both reading regimens. RESULTS The proportion of cancers detected was 199 of 227 (87.7%) for double reading and 198 of 227 (87.2%) for single reading with computer-aided detection (P=0.89). The overall recall rates were 3.4% for double reading and 3.9% for single reading with computer-aided detection; the difference between the rates was small but significant (P<0.001). The estimated sensitivity, specificity, and positive predictive value for single reading with computer-aided detection were 87.2%, 96.9%, and 18.0%, respectively. The corresponding values for double reading were 87.7%, 97.4%, and 21.1%. There were no significant differences between the pathological attributes of tumors detected by single reading with computer-aided detection alone and those of tumors detected by double reading alone. CONCLUSIONS Single reading with computer-aided detection could be an alternative to double reading and could improve the rate of detection of cancer from screening mammograms read by a single reader. (ClinicalTrials.gov number, NCT00450359.)

Selectivities of opioid peptide analogues as agonists and antagonists at the δ-receptor

1 The endogenous opioid ligands interact with more than one of the μ‐, δ‐ and κ‐binding sites. By the use of binding assays and bioassays, enkephalin analogues have been assessed for their selectivity for binding at the (5‐binding site and for their agonist and antagonist activities at the δ‐receptor. The electrically‐induced contractions of myenteric plexus‐longitudinal muscle preparations of the guinea‐pig ileum were inhibited by μ‐ and κ‐receptor ligands. Inhibitions were seen with μ‐, δ‐ and κ‐receptor ligands in the mouse vas deferens, mainly with μ‐receptor ligands in the rat vas deferens and only with κ‐receptor ligands in the rabbit vas deferens. 2 From observations on a considerable number of [Leu5] enkephalin analogues, it has been concluded that [d‐Pen2, d‐Pen5] enkephalin and [d‐Pen2, l‐Pen5] enkephalin are the most selective δ‐agonists and that N,N‐diallyl‐Tyr‐Aib‐Aib‐Phe‐Leu‐OH is the most selective antagonist (Aib = α‐aminoisobutyric acid). The binding of these peptides at the δ‐site is 99% of the total binding. As to potency, the agonists are superior to the antagonists.

COMPARISON OF THE BINDING CHARACTERISTICS OF TRITIATED OPIATES AND OPIOID PEPTIDES

1 Binding assays on homogenates of guinea‐pig brain showed that the maximal number of binding sites was different for different tritiated ligands interacting with the opiate receptors. 2 At 25°C the binding capacity of morphine or dihydromorphine was only about 3 pmol/g fresh brain whereas etorphine and d‐Ala2‐l‐Leu5‐ and d‐Ala2‐l‐Met5‐enkephalin amide had capacities of 13 to 15 pmol/g brain. d‐Ala2‐d‐Leu5‐enkephalin had an intermediate capacity of about 6 pmol/g brain. 3 The binding capacities of the natural methionine‐ and leucine‐enkephalins measured at 0°C were 5 to 6 pmol/g brain. At this temperature, the binding capacity of dihydromorphine, d‐Ala2‐d‐Leu5‐enkephalin and of the two enkephalin amides was only slightly lower than at 25°C. 4 In assays in which unlabelled ligand competed with the same labelled ligand, the inhibition constants (K1) were equal to or not more than twice as large as the equilibrium dissociation constant (Kd) determined in saturation assays. In contrast, the K1 of unlabelled dihydromorphine against [3H]‐d‐Ala2‐d‐Leu5‐enkephalin or of unlabelled d‐Ala2‐d‐Leu5‐enkephalin against [3H]‐dihydromorphine were about 20 times higher than the respective Kd values. 5 When for a given compound the ratio of the K1 value against [3H]‐d‐Ala2‐d‐Leu5‐enkephalin to the K1 value against [3H]‐dihydromorphine (discrimination ratio) is calculated, a high value indicates selectivity in favour of the μ‐receptor and a low value selectivity in favour of the δ‐receptor. The most selective μ‐agonist known so far is normorphine with a discrimination ratio of 70 and the most selective δ‐agonist is d‐Ala2‐d‐Leu5‐enkephalin with a ratio of 0.11. The selectivity of the known antagonists is in favour of the μ‐receptor, since their discrimination ratios are larger than 1, varying between 10 for naloxone and 4 for Mr 2266.

Species differences in the concentrations and distributions of opioid binding sites

Binding at the mu, delta- and kappa-types of opioid binding sites was compared in homogenates from the brains of guinea-pig, rabbit, rat and two mouse strains, under conditions of selective labelling. Species differences were shown by two observations. Firstly, analysis of saturation curves in homogenates of brain from which the cerebellum had been removed showed that in guinea-pig brain the opioid binding sites consist of 24% mu-sites, 32% delta-sites and 44% kappa-sites. In contrast, in rabbit brain the corresponding values are 43% mu-sites, 19% delta-sites and 37% kappa-sites and in rat brain, 46% mu-sites, 42% delta-sites and 12% kappa-sites. In the brains of DBA/2 mice the opioid binding sites are comprised of 51% mu-sites, 29% delta-sites and 20% kappa-sites and in C57BL/10 mice, of 44% mu-sites, 35% delta-sites and 21% kappa-sites; these strain differences are due to significant differences in the concentrations of the mu-sites. Secondly, species differences were found when the binding of single concentrations of tritiated ligands (1 X KD value in whole brain) was determined at mu-, delta- and kappa-sites in six brain regions from guinea-pig, rat or rabbit.

The TOMMY trial: a comparison of TOMosynthesis with digital MammographY in the UK NHS Breast Screening Programme--a multicentre retrospective reading study comparing the diagnostic performance of digital breast tomosynthesis and digital mammography with digital mammography alone.

BACKGROUND Digital breast tomosynthesis (DBT) is a three-dimensional mammography technique with the potential to improve accuracy by improving differentiation between malignant and non-malignant lesions. OBJECTIVES The objectives of the study were to compare the diagnostic accuracy of DBT in conjunction with two-dimensional (2D) mammography or synthetic 2D mammography, against standard 2D mammography and to determine if DBT improves the accuracy of detection of different types of lesions. STUDY POPULATION Women (aged 47-73 years) recalled for further assessment after routine breast screening and women (aged 40-49 years) with moderate/high of risk of developing breast cancer attending annual mammography screening were recruited after giving written informed consent. INTERVENTION All participants underwent a two-view 2D mammography of both breasts and two-view DBT imaging. Image-processing software generated a synthetic 2D mammogram from the DBT data sets. RETROSPECTIVE READING STUDY In an independent blinded retrospective study, readers reviewed (1) 2D or (2) 2D + DBT or (3) synthetic 2D + DBT images for each case without access to original screening mammograms or prior examinations. Sensitivities and specificities were calculated for each reading arm and by subgroup analyses. RESULTS Data were available for 7060 subjects comprising 6020 (1158 cancers) assessment cases and 1040 (two cancers) family history screening cases. Overall sensitivity was 87% [95% confidence interval (CI) 85% to 89%] for 2D only, 89% (95% CI 87% to 91%) for 2D + DBT and 88% (95% CI 86% to 90%) for synthetic 2D + DBT. The difference in sensitivity between 2D and 2D + DBT was of borderline significance (p = 0.07) and for synthetic 2D + DBT there was no significant difference (p = 0.6). Specificity was 58% (95% CI 56% to 60%) for 2D, 69% (95% CI 67% to 71%) for 2D + DBT and 71% (95% CI 69% to 73%) for synthetic 2D + DBT. Specificity was significantly higher in both DBT reading arms for all subgroups of age, density and dominant radiological feature (p < 0.001 all cases). In all reading arms, specificity tended to be lower for microcalcifications and higher for distortion/asymmetry. Comparing 2D + DBT to 2D alone, sensitivity was significantly higher: 93% versus 86% (p < 0.001) for invasive tumours of size 11-20 mm. Similarly, for breast density 50% or more, sensitivities were 93% versus 86% (p = 0.03); for grade 2 invasive tumours, sensitivities were 91% versus 87% (p = 0.01); where the dominant radiological feature was a mass, sensitivities were 92% and 89% (p = 0.04) For synthetic 2D + DBT, there was significantly (p = 0.006) higher sensitivity than 2D alone in invasive cancers of size 11-20 mm, with a sensitivity of 91%. CONCLUSIONS The specificity of DBT and 2D was better than 2D alone but there was only marginal improvement in sensitivity. The performance of synthetic 2D appeared to be comparable to standard 2D. If these results were observed with screening cases, DBT and 2D mammography could benefit to the screening programme by reducing the number of women recalled unnecessarily, especially if a synthetic 2D mammogram were used to minimise radiation exposure. Further research is required into the feasibility of implementing DBT in a screening setting, prognostic modelling on outcomes and mortality, and comparison of 2D and synthetic 2D for different lesion types. STUDY REGISTRATION Current Controlled Trials ISRCTN73467396. FUNDING This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 19, No. 4. See the HTA programme website for further project information.

Unexpected antagonism in the rat vas deferens by benzomorphans which are agonists in other pharmacological tests.

The benzomorphans, ethylketazocine, bremazocine and MR 2034 are pure agonists in the guinea‐pig ileum and mouse vas deferens but are competitive antagonists without agonist activity in the rat vas deferens.

Accuracy of Digital Breast Tomosynthesis for Depicting Breast Cancer Subgroups in a UK Retrospective Reading Study (TOMMY Trial)

PURPOSE To compare the diagnostic performance of two-dimensional (2D) mammography, 2D mammography plus digital breast tomosynthesis (DBT), and synthetic 2D mammography plus DBT in depicting malignant radiographic features. MATERIALS AND METHODS In this multicenter, multireader, retrospective reading study (the TOMMY trial), after written informed consent was obtained, 8869 women (age range, 29-85 years; mean, 56 years) were recruited from July 2011 to March 2013 in an ethically approved study. From these women, a reading dataset of 7060 cases was randomly allocated for independent blinded review of (a) 2D mammography images, (b) 2D mammography plus DBT images, and (c) synthetic 2D mammography plus DBT images. Reviewers had no access to results of previous examinations. Overall sensitivities and specificities were calculated for younger women and those with dense breasts. RESULTS Overall sensitivity was 87% for 2D mammography, 89% for 2D mammography plus DBT, and 88% for synthetic 2D mammography plus DBT. The addition of DBT was associated with a 34% increase in the odds of depicting cancer (odds ratio [OR] = 1.34, P = .06); however, this level did not achieve significance. For patients aged 50-59 years old, sensitivity was significantly higher (P = .01) for 2D mammography plus DBT than it was for 2D mammography. For those with breast density of 50% or more, sensitivity was 86% for 2D mammography compared with 93% for 2D mammography plus DBT (P = .03). Specificity was 57% for 2D mammography, 70% for 2D mammography plus DBT, and 72% for synthetic 2D mammography plusmDBT. Specificity was significantly higher than 2D mammography (P < .001in both cases) and was observed for all subgroups (P < .001 for all cases). CONCLUSION The addition of DBT increased the sensitivity of 2D mammography in patients with dense breasts and the specificity of 2D mammography for all subgroups. The use of synthetic 2D DBT demonstrated performance similar to that of standard 2D mammography with DBT. DBT is of potential benefit to screening programs, particularly in younger women with dense breasts. (©) RSNA, 2015.

THE INHIBITORY EFFECTS OF PRESYNAPTIC α‐ADRENOCEPTOR AGONISTS ON CONTRACTIONS OF GUINEA‐PIG ILEUM AND MOUSE VAS DEFERENS IN THE MORPHINE‐DEPENDENT AND WITHDRAWN STATES PRODUCED in vitro

1 Isolated ilea from guinea‐pigs implanted with morphine pellets were stimulated coaxially, either with or without morphine present in the bath fluid, and the longitudinal contractions recorded. 2 In the absence of morphine the inhibitory effects of the presynaptic α‐adrenoceptor agonists, clonidine and oxymetazoline were much reduced and the dose‐response curve was flat. This state of ‘withdrawal’ was readily reversed by morphine and levorphanol but not its inactive (+)‐isomer, dextrorphan. 3 The κ‐agonists, ketazocine and ethylketazocine, also restored the effects of clonidine as did the opioid peptides Tyr‐d‐Ala‐Gly‐Phe‐d‐Leu, acting preferentially on δ‐receptors, and Tyr‐d‐Ala‐Gly‐MePhe‐Met(O)‐ol, acting mainly on μ‐receptors. 4 The inhibitory effects of adrenaline and adenosine 3′,5′‐diphosphate were reduced at low but not at high concentrations. 5 In contrast, the inhibitory effect of clonidine on the electrically evoked contractions of vasa deferentia from mice implanted with morphine pellets was not abolished by the lack of morphine in the bath fluid or by addition of naloxone. 6 A possible explanation is suggested for the loss of the inhibitory effects of presynaptic α‐adrenoceptor agonists in the withdrawn state of the dependent ileum.

Visually assessed breast density, breast cancer risk and the importance of the craniocaudal view.

IntroductionMammographic density is known to be a strong risk factor for breast cancer. A particularly strong association with risk has been observed when density is measured using interactive threshold software. This, however, is a labour-intensive process for large-scale studies.MethodsOur aim was to determine the performance of visually assessed percent breast density as an indicator of breast cancer risk. We compared the effect on risk of density as measured with the mediolateral oblique view only versus that estimated as the average density from the mediolateral oblique view and the craniocaudal view. Density was assessed using a visual analogue scale in 10,048 screening mammograms, including 311 breast cancer cases diagnosed at that screening episode or within the following 6 years.ResultsWhere only the mediolateral oblique view was available, there was a modest effect of breast density on risk with an odds ratio for the 76% to 100% density relative to 0% to 25% of 1.51 (95% confidence interval 0.71 to 3.18). When two views were available, there was a considerably stronger association, with the corresponding odds ratio being 6.77 (95% confidence interval 2.75 to 16.67).ConclusionThis indicates that a substantial amount of information on risk from percentage breast density is contained in the second view. It also suggests that visually assessed breast density has predictive potential for breast cancer risk comparable to that of density measured using the interactive threshold software when two views are available. This observation needs to be confirmed by studies applying the different measurement methods to the same individuals.