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Longitudinal trajectories of intellectual and adaptive functioning in adolescents and adults with Williams syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2016; 60:920-932. [PMID: 27273269 DOI: 10.1111/jir.12303] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 03/30/2016] [Accepted: 05/06/2016] [Indexed: 06/06/2023]
Abstract
BACKGROUND Williams syndrome (WS) is associated with a distinct cognitive-behavioural phenotype including mild to moderate intellectual disability, visual-spatial deficits, hypersociability, inattention and anxiety. Researchers typically characterise samples of individuals with WS by their intellectual functioning and adaptive behaviour. Because of the low prevalence of the syndrome, researchers often include participants with WS across a broad age range throughout childhood and adulthood and assume participants demonstrate consistent cognitive development across ages. Indeed, IQ scores are generally stable for children and adolescents with WS, although there are significant individual differences. It is less clear whether this pattern of stable intellectual ability persists into adulthood. Furthermore, while adaptive behaviour is an important indicator of an individual's ability to apply their conceptual skills to everyday functioning, conflicting findings on the trajectories of adaptive behaviour in adolescents and adults with WS have been reported. The current study examined longitudinal profiles of cognitive and adaptive functioning in adolescents and adults with WS. METHOD To examine cognitive functioning, participants included 52 individuals with WS (51.9% men) who were assessed with the Kaufman Brief Intelligence Test, 2nd edition (KBIT-2) between two and seven times. At their first assessment, participants had a mean age of 25.4 years (SD = 8.4), ranging in age from 14.2 to 48.9 years. To assess adaptive behaviour, participants included a subset of 28 individuals with WS whose parents completed the Vineland Adaptive Behavior Scale, 2nd edition (VABS-II) between two and five times. At their initial administration, participants ranged from 17.1-40.2 years of age, with a mean age of 26.5 years (SD = 7.3). A series of multilevel models were used to examine changes in KBIT-2 Composite IQ, Verbal IQ and Nonverbal IQ standard scores over time, as well as the Adaptive Behavior Composite, and the Communication, Daily Living Skills and Socialization subdomains of the VABS-II. RESULTS Consistent with the WS cognitive profile, IQ scores were significantly lower than the general population IQ score of 100, and there was significant variability in individual IQ scores and slopes. KBIT-2 IQ scores were generally stable across adolescents and adults with WS. Adaptive behaviour scores were significantly lower than the population mean score of 100, and there was significant variability in individuals' adaptive behaviour scores but not trajectories. However, in contrast to the findings with the KBIT-2, VABS-II scores were observed to significantly decrease over time. CONCLUSION Findings suggest that while intellectual functioning remains stable, adaptive functioning does not remain stable across adolescence and adulthood in individuals with WS. Implications for the relation between cognitive and adaptive functioning across development are discussed, with a focus on how this relates to specific aspects of the WS phenotype.
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Internet use and online safety in adults with Williams syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2016; 60:1020-1030. [PMID: 27174494 DOI: 10.1111/jir.12281] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 12/10/2015] [Accepted: 03/01/2016] [Indexed: 06/05/2023]
Abstract
BACKGROUND Individuals with intellectual and developmental disabilities (IDD) increasingly have access to the Internet. Whilst Internet access increases opportunities for social connection for individuals with IDD, it also may increase risk of victimisation. Adults with Williams syndrome (WS), who display an extreme pro-social drive to engage with both familiar and unfamiliar people, might be especially vulnerable to online victimisation. This study first explores how often and why individuals with WS use the Internet and social networking sites. Next, the online vulnerability of individuals with WS is assessed through responses to hypothetical scenarios of potentially dangerous online interactions. METHOD Twenty-eight young adults with WS (mean age = 27.7 years) and their parents completed questionnaires about their Internet and social networking use and parental oversight. Participants with WS then responded to hypothetical scenarios assessing their likelihood to take social and non-social risks online. RESULTS Most participants with WS frequently use the Internet and the majority visit social networking sites every day or almost every day, with little parental supervision or oversight. Individuals with WS interact with both known and unknown individuals through social networking sites. Participants are more likely to agree to engage in socially risky behaviours compared to risky behaviours that are not social in nature when online. For example, participants were more likely to agree to meet an 'online friend' in person than they were to give their bank account information for winning a 'contest'. CONCLUSIONS Individuals with WS, who are a socially vulnerable group in the real world, display behaviours that could also lead to victimisation online as well. As the Internet continues to become more accessible, more research is needed to increase online safety of individuals with WS and other IDDs. Implications for intervention and future research are discussed.
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Abstract
The study investigated the effect of different input selections on the performance of artificial neural networks in screening for acute myocardial infarction (AMI) in Malaysian patients complaining of chest pain. We used hospital data to create neural networks with four input selections and used these to diagnose AMI. A 10-fold cross-validation and committee approach was used. All the neural networks using various input selections outperformed a multiple logistic regression model, although the difference was not statistically significant. The neural networks achieved an area under the ROC curve of 0.792 using nine inputs, whereas multiple logistic regression achieved 0.739 using 64 inputs. Sensitivity levels of over 90 per cent were achieved using low output threshold levels. Specificity levels of over 90 per cent were achieved using threshold levels of 0.4-0.5. Thus neural networks can perform as well as multiple logistic regression models even when using far fewer inputs.
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Three-dimensional rendering of otolith growth using phase contrast synchrotron tomography. JOURNAL OF FISH BIOLOGY 2016; 88:2075-2080. [PMID: 27071346 DOI: 10.1111/jfb.12949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 02/08/2016] [Indexed: 06/05/2023]
Abstract
A three-dimensional computer reconstruction of a plaice Pleuronectes platessa otolith is presented from data acquired by the Diamond Light synchrotron, beamline I12, X-ray source, a high energy (53-150 keV) source particularly well suited to the study of dense objects. The data allowed non-destructive rendering of otolith structure, and for the first time allows otolith annuli (internal ring structures) to be analysed in X-ray tomographic images.
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Evaluation of a stranger safety training programme for adults with Williams syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2014; 58:903-914. [PMID: 24341290 DOI: 10.1111/jir.12108] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/15/2013] [Indexed: 06/03/2023]
Abstract
BACKGROUND Individuals with Williams syndrome (WS) are reported to display increased sociability towards strangers, leading to increased social vulnerability. No research has examined real life interactions of adults with WS towards strangers and no interventions have been implemented to teach stranger safety skills to this population. METHOD Twenty-one adults with WS participated in 3 days of behaviour skills training to learn how to respond to a stranger lure. Skill acquisition was assessed in situ; confederate strangers approached participants, presented a lure and recorded the participants' response. RESULTS Prior to intervention, 14% of participants walked away from a stranger. Participants were able to accurately use the skills in role play. After training, 62% of participants said 'no' and walked away and only 14% agreed to leave with the stranger during in situ assessments. CONCLUSIONS Individuals with WS are at-risk but can learn how to appropriately respond to lures from strangers. Further research is needed to increase use of safety skills in various conditions.
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Selective transcription of p53 target genes by zinc finger-p53 DNA binding domain chimeras. ACTA ACUST UNITED AC 2005; 1681:15-27. [PMID: 15566940 DOI: 10.1016/j.bbaexp.2004.09.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2004] [Revised: 09/21/2004] [Accepted: 09/22/2004] [Indexed: 11/26/2022]
Abstract
Active p53 stimulates the transcription of a number of key genes, including the pro-apoptotic gene bax, as well as p21, a cell cycle regulator. In this study we constructed novel chimeric zinc finger-p53 DNA binding domain (DBD) transcription factors designed to bind to the promoters of specific p53 regulated genes. In order to selectively increase the expression of Bax, we coupled a pre-selected three-zinc finger (Zif) peptide targeted to a sequence in the bax promoter to a minimal p53 DBD. This chimeric protein could increase reporter gene transcription from a minimal bax promoter (up to 10-fold) but not from a minimal p21 promoter in p53-deficient Saos-2 cells. However, fusion proteins carrying longer p53 DBDs displayed entirely different selectivity and potency. Thus, Zif-p53 DBD chimeras containing N- and C-terminal extensions of the minimal DBD could increase transcription driven by a minimal p21 promoter up to 800-fold. These chimeras preferred the minimal p21 promoter up to 500-fold over the minimal bax promoter. Additionally, endogenous p21 message and protein levels were increased in cells expressing the p21 selective Zif-p53 DBD chimera and expression of the chimeric proteins resulted in partial cell cycle arrest. Cell fractionation experiments indicated that the Zifs enhanced nuclear localization of the Zif-p53 DBD chimera. These studies suggest that it is possible to create chimeric transcription factors able to strongly and selectively activate genes downstream of p53.
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9
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Abstract
[reaction--see text] The semisynthetic conversion of nodulisporic acid A (1) into a set of three heterocyclic side chain derivatives provided compounds, highlighted by 6, with an improved spectrum of ectoparasiticidal activity and pharmacokinetic profile relative to the natural product.
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11
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Abstract
Nodulisporic acid A (NSA) has been shown previously to be safe in dogs and to deliver >90% flea control for 4 days following a single oral administration. Three newly prepared nodulisporamide derivatives were subsequently identified from an artificial membrane flea feeding system as exhibiting potency substantially greater than NSA. To determine if they have superior in vivo activity, these 3 nodulisporamides, as well as NSA, were evaluated in dogs at 15 mg/kg/os. Parasite challenges were made by placing 100 live Ctenocephalides felis fleas onto the dorsum of dogs every 48 hr and examining efficacy at each of those intervals over a 22-day period. Results showed that NSA produced >90% efficacy at day 2 and 81% efficacy at day 4, and its residual flea killing fell to approximately 50% by day 6 posttreatment. All dogs treated with the 3 new experimental nodulisporamides were 100% protected from flea challenges to day 8 posttreatment, and 2 of the compounds continued to produce >90% residual activity to 2 wk posttreatment. Pharmacokinetic analysis showed that plasma profiles and half-lives of NSA and these 3 new compounds correlated closely with flea efficacy. These results demonstrate that specific substitutions to the pharmacophore of NSA can substantially increase the duration of activity against fleas.
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Abstract
A series of 2-(3,5-dimethylphenyl)tryptamine derivatives was prepared and evaluated on a rat gonadotropin releasing hormone receptor assay. Some para-substituents on the 4-phenylbutyl side chain attached to the tryptamine nitrogen led to compounds with potent GnRH receptor binding. The study has helped define structural requirements for GnRH receptor binding for the 2-aryltryptamine GnRH antagonists.
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Abstract
A series of heterocyclic 2-(3,5-dimethylphenyl)tryptamine derivatives was prepared and evaluated on a rat gonadotropin releasing hormone receptor assay. The carbon tether length and heterocyclic ring attached to the amino group of 2-(3,5-dimethylphenyl)tryptamine were varied. Several of these derivatives were potent GnRH antagonists with the most potent compound having an IC50 of 16 nM.
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Beta(3)-adrenoceptor agonist-induced increases in lipolysis, metabolic rate, facial flushing, and reflex tachycardia in anesthetized rhesus monkeys. J Pharmacol Exp Ther 2001; 297:299-307. [PMID: 11259557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/19/2023] Open
Abstract
The effects of two beta(3)-adrenergic receptor agonists, (R)-4-[4-(3-cyclopentylpropyl)-4,5-dihydro-5-oxo-1H-tetrazol-1-yl]-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)ethyl]amino]ethyl]phenyl]benzenesulfonamide and (R)-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)- ethyl]amino]ethyl]phenyl]-1-(4-octylthiazol-2-yl)-5-indolinesulfonamide, on indices of metabolic and cardiovascular function were studied in anesthetized rhesus monkeys. Both compounds are potent and specific agonists at human and rhesus beta(3)-adrenergic receptors. Intravenous administration of either compound produced dose-dependent lipolysis, increase in metabolic rate, peripheral vasodilatation, and tachycardia with no effects on mean arterial pressure. The increase in heart rate in response to either compound was biphasic with an initial rapid component coincident with the evoked peripheral vasodilatation and a second more slowly developing phase contemporaneous with the evoked increase in metabolic rate. Because both compounds exhibited weak binding to and activation of rhesus beta(1)-adrenergic receptors in vitro, it was hypothesized that the increase in heart rate may be reflexogenic in origin and proximally mediated via release of endogenous norepinephrine acting at cardiac beta(1)-adrenergic receptors. This hypothesis was confirmed by determining that beta(3)-adrenergic receptor agonist-evoked tachycardia was attenuated in the presence of propranolol and in ganglion-blocked animals, under which conditions there was no reduction in the evoked vasodilatation, lipolysis, or increase in metabolic rate. It is not certain whether the beta(3)-adrenergic receptor-evoked vasodilatation is a direct effect of compounds at beta(3)-adrenergic receptors in the peripheral vasculature or is secondary to the release or generation of an endogenous vasodilator. Peripheral vasodilatation in response to beta(3)-adrenergic receptor agonist administration was not attenuated in animals administered mepyramine, indomethacin, or calcitonin gene-related peptide(8-37). These findings are consistent with a direct vasodilator effect of beta(3)-adrenergic receptor agonists.
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Abstract
The discovery of the potency-enhancing effect of 5-substitutions on the novel 2-arylindoles as nonpeptidyl GnRH receptor antagonists led to the identification of several analogues with high affinities on the GnRH receptor. The syntheses and SARs of these 5-substituted-2-arylindole analogues are reported.
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Initial structure-activity relationship of a novel class of nonpeptidyl GnRH receptor antagonists: 2-arylindoles. Bioorg Med Chem Lett 2001; 11:509-13. [PMID: 11229759 DOI: 10.1016/s0960-894x(00)00707-1] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A nonpeptidyl GnRH receptor antagonist (1), with a unique 2-arylindole core, was identified through the Merck in-house screening for binding affinity on the rat GnRH receptor. SAR studies directed toward the alkoxy-ethanolamine and 2-aryl groups resulted in a simpler lead structure with improved activity. This compound 50 exhibits a 60-fold improvement in binding activity over our initial lead 1.
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Human beta3 adrenergic receptor agonists containing cyanoguanidine and nitroethylenediamine moieties. Bioorg Med Chem Lett 2001; 11:379-82. [PMID: 11212115 DOI: 10.1016/s0960-894x(00)00669-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Pyridineethanolamine derivatives containing cyanoguanidine or nitroethylenediamine moieties were examined as human beta3 adrenergic receptor (AR) agonists. Notably, indoline derivatives 6a and 11 were potent beta3 AR agonists (beta3 EC50 = 13 and 19 nM, respectively), which showed good selectivity over binding to and minimal activation of the beta1 and beta2 ARs.
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Broad spectrum antiprotozoal agents that inhibit histone deacetylase: structure-activity relationships of apicidin. Part 1. Bioorg Med Chem Lett 2001; 11:107-11. [PMID: 11206438 DOI: 10.1016/s0960-894x(00)00604-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Apicidin, a natural product recently isolated at Merck, inhibits both mammalian and protozoan histone deacetylases (HDACs). The conversion of apicidin, a nanomolar inhibitor of HDACs, into a series of side-chain analogues that display picomolar enzyme affinity is described within this structure-activity study.
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Broad spectrum antiprotozoal agents that inhibit histone deacetylase: structure-activity relationships of apicidin. Part 2. Bioorg Med Chem Lett 2001; 11:113-7. [PMID: 11206439 DOI: 10.1016/s0960-894x(00)00605-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Recently isolated at Merck, apicidin inhibits both mammalian and protozoan histone deacetylases (HDACs). The conversion of apicidin, a nonselective nanomolar inhibitor of HDACs, into a series of picomolar indole-modified and parasite-selective tryptophan-replacement analogues is described within this structure-activity study.
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Multiscale color invariants based on the human visual system. IEEE TRANSACTIONS ON IMAGE PROCESSING : A PUBLICATION OF THE IEEE SIGNAL PROCESSING SOCIETY 2001; 10:1630-1638. [PMID: 18255505 DOI: 10.1109/83.967391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
This paper proposes a new representation for color texture using a set of multiscale illuminant invariant features. The approach was specifically developed to investigate the feasibility of using machine vision to automatically monitor populations of animal species in ecologically sensitive regions, such as the Amazon Forest. The approach uses a combination of Finlayson's (1994) color angle idea and Gabor multichannel filters and was inspired by the multichannel model of the human visual system (HVS). Using a database of color textures from three species of Amazonian monkey, and also a previously published reference database of color regions, we show that the approach performs better than methods based on color angles or Gabor filters alone. The Monkey database was compiled from texture segments extracted from a video of the Amazon Forest using a spatio-temporal segmentation algorithm. The approach is evaluated by applying two different classification tests in order to measure the quality of the recognition features root mean square (RMS) analysis and receiver operating characteristic (ROC) analysis.
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Synthesis of apicidin-derived quinolone derivatives: parasite-selective histone deacetylase inhibitors and antiproliferative agents. J Med Chem 2000; 43:4919-22. [PMID: 11124001 DOI: 10.1021/jm0001976] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Apicidin's indole was efficiently converted into a series of N-substituted quinolone derivatives by indole N-alkylation followed by a two-step, one-pot, ozonolysis/aldol condensation protocol. The new quinolones exhibited good parasite selectivity and potency both at the level of their molecular target, histone deacetylase, and in their whole cell antiproliferative activity in vitro.
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L-750355, a human beta3-adrenoceptor agonist; in vitro pharmacology and profile of activity in vivo in the rhesus monkey. Eur J Pharmacol 2000; 407:175-81. [PMID: 11050305 DOI: 10.1016/s0014-2999(00)00724-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The profile of in vitro and in vivo biology of a human beta3-adrenoceptor agonist, (S)-N-[4-[2-[[3[(2-amino-5-pyridinyl)oxy]-2-hydroxy-propyl]amino]-eth yl]-phenyl]-4-isopropylbenzenesulfonamide, L-750355, is described. Using cloned human and rhesus beta1-, beta2- and beta3-adrenoceptors, expressed in Chinese hamster ovary (CHO) cells, L-750355 was shown to be a potent, albeit partial, agonist for the human (EC(50)=10 nM; % maximal receptor activation=49%) and rhesus (EC(50)=28 nM; % maximal receptor activation=34%) beta3-adrenoceptors. Furthermore, L-750355 stimulates lipolysis in rhesus adipocytes in vitro. L-750355 is a weak partial agonist (EC(50)=3.2 microM; % maximal receptor activation=33% ) for the human beta1-adrenoceptor but exhibits no agonist activity for rhesus beta1- or beta2-adrenoceptors of either human or rhesus origin. Administration of L-750355 to anesthetized rhesus monkeys, as a series of rising dose intravenous infusions, evokes dose-dependent glycerolemia and tachycardia with no change in mean arterial blood pressure or plasma potassium. The dose-response curve for L-750355-induced glycerolemia lies to the left of that for tachycardia. Propranolol, at a dose (0.3 mg/kg, i.v. ) that attenuates isoproterenol-induced changes in heart rate and glycerolemia, abolished L-750355-induced tachycardia but had no effect on L-750355-induced glycerolemia.
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Discovery of a potent, orally bioavailable beta(3) adrenergic receptor agonist, (R)-N-[4-[2-[[2-hydroxy-2-(3-pyridinyl)ethyl]amino]ethyl]phenyl]-4-[4 -[4-(trifluoromethyl)phenyl]thiazol-2-yl]benzenesulfonamide. J Med Chem 2000; 43:3832-6. [PMID: 11052788 DOI: 10.1021/jm000286i] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
As part of our investigation into the development of orally bioavailable beta(3) adrenergic receptor agonists, we have identified a series of pyridylethanolamine analogues possessing a substituted thiazole benzenesulfonamide pharmacophore that are potent human beta(3) agonists with excellent selectivity against other human beta receptor subtypes. Several of these compounds also exhibited an improved pharmacokinetic profile in dogs. For example, thiazole sulfonamide 2e (R = 4-F(3)C-C(6)H(4)) is a potent full beta(3) agonist (EC(50) = 3.6 nM, 94% activation) with >600-fold selectivity over the human beta(1) and beta(2) receptors, which also displays good oral bioavailability in several mammalian species, as well as an extended duration of action.
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Tetrahydroisoquinoline derivatives containing a benzenesulfonamide moiety as potent, selective human beta3 adrenergic receptor agonists. Bioorg Med Chem Lett 2000; 10:2283-6. [PMID: 11055339 DOI: 10.1016/s0960-894x(00)00459-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tetrahydroisoquinoline derivatives containing a 4-(hexylureido)benzenesulfonamide were examined as human beta3 adrenergic receptor (AR) agonists. Notably, 4,4-biphenyl derivative 9 was a 6 nM full agonist of the beta3 AR. Naphthyloxy compound 18 (beta3 EC50 = 78 nM) did not activate the beta1 and beta2 ARs at 10 microM, and showed >1000-fold selectivity over binding to the beta1 and beta2 ARs.
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Abstract
Medicinal chemistry efforts were initiated to identify the key constituents of the nodulisporic acid A (1) pharmacophore that are integral to its potent insecticidal activity. New semisynthetic derivatives delineated 1 into 'permissive' and 'nonpermissive' regions and led to the discovery of new nodulisporamides with significantly improved flea efficacy.
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Human beta3-adrenergic receptor agonists containing 1,2,3-triazole-substituted benzenesulfonamides. Bioorg Med Chem Lett 2000; 10:2111-4. [PMID: 10999482 DOI: 10.1016/s0960-894x(00)00422-4] [Citation(s) in RCA: 182] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Compounds containing a 1,2,3-triazole-substituted benzenesulfonamide were prepared and found to be potent and selective human beta3-adrenergic receptor agonists. The most interesting compound, trifluoromethylbenzyl analogue 12e (beta3 EC50 = 3.1 nM with >1500-fold selectivity over binding to both beta1- and beta2 receptors), stimulates lipolysis in the rhesus monkey (ED50 = 0.36 mg/kg) and is 25% orally bioavailable in the dog.
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Potent, selective 3-pyridylethanolamine beta3 adrenergic receptor agonists possessing a thiazole benzenesulfonamide pharmacophore. Bioorg Med Chem Lett 2000; 10:1971-3. [PMID: 10987429 DOI: 10.1016/s0960-894x(00)00390-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
A series of thiazole benzenesulfonamide-substituted 3-pyridylethanolamines was prepared and evaluated for their human beta3 adrenergic receptor agonist activity. Incorporation of aryl and heteroaryl substitution in the 4-position of the thiazole ring resulted in a number of highly potent and selective beta3 agonists. Results of preliminary in vivo evaluation of several of these compounds is described.
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Abstract
As a part of our investigation into the development of orally bioavailable beta3 adrenergic receptor agonists, we have identified a series of substituted oxazole derivatives that are potent beta3 agonists with excellent selectivity against other beta receptors. Several of these compounds showed excellent oral bioavailability in dogs. One example, cyclopentylethyloxazole 5f is a potent beta3 agonist (EC50 = 14 nM, 84% activation) with 340-fold and 160-fold selectivity over beta1 and beta2 receptors, respectively, and has 38% oral bioavailability in dogs.
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Abstract
5-n-Pentyl oxadiazole substituted benzenesulfonamide 8 is a potent and selective beta3 adrenergic receptor agonist (beta3 EC50 = 23 nM, beta1 IC50 = 3000 nM, beta2 IC50 = 3000 nM). The compound has high oral bioavailability in dogs (62%) and rats (36%) and is among the most orally bioavailable beta3 adrenergic receptor agonists reported to date.
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Synthesis and SAR of benzyl and phenoxymethylene oxadiazole benzenesulfonamides as selective beta3 adrenergic receptor agonist antiobesity agents. Bioorg Med Chem Lett 2000; 10:1431-4. [PMID: 10888325 DOI: 10.1016/s0960-894x(00)00268-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Benzyl and phenoxymethylene substituted oxadiazoles are potent and orally bioavailable beta3 adrenergic receptor (AR) agonists. The 4-trifluormethoxy substituted 5-benzyl oxadiazole 5f has an EC50 of 8 nM in the beta3 AR agonist assay with 100-fold selectivity over beta1 and beta2 AR binding inhibition activity. Its oral bioavailability in dogs is 30 +/- 4%, with a half-life of 3.8 +/- 0.4 h. In the anesthetized rhesus, 5f evoked a dose-dependent glycerolemia (ED50Gly = 0.15 mg/kg). Under these conditions a heart rate increase of 15% was observed at a dose level of 10 mg/kg.
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Potent antagonists of gonadotropin releasing hormone receptors derived from quinolone-6-carboxamides. Bioorg Med Chem Lett 2000; 10:443-7. [PMID: 10743944 DOI: 10.1016/s0960-894x(00)00024-x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
SAR studies which focused upon the C-6 position of a recently described series of quinolone gonadotropin releasing hormone antagonists are reported. Synthetic access to diverse quinolone-6-carboxamides was achieved via the palladium-catalyzed amino-carbonylation reactions of iodide 4 with various amines. Amides related to 9y were especially potent, functional antagonists of rat and human GnRH receptors.
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Abstract
Systematic investigation of acyclic analogs of L-692,429, the prototype benzolactam growth hormone secretagogue, has helped to further define the structural requirements for the release of growth hormone from rat pituitary cells for this class of secretagogues.
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Identification and initial structure-activity relationships of a novel non-peptide quinolone GnRH receptor antagonist. Bioorg Med Chem Lett 1999; 9:2615-20. [PMID: 10498220 DOI: 10.1016/s0960-894x(99)00446-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Screening of the Merck sample collection for non-peptide compounds with binding affinity for the rat GnRH receptor led to the identification of the substituted quinolone (1) as a lead compound in the search for a non-peptide GnRH receptor antagonist. Substantial improvements in potency (approximately 300 fold) were achieved by addition of an alkyl amine at the 4-position, a 3,5-dimethylphenyl group at the 3-position and 6-nitro-7-chloro-substitution of the 1 H-quinolone core.
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34
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Investigation of the 4-O-alkylamine substituent of non-peptide quinolone GnRH receptor antagonists. Bioorg Med Chem Lett 1999; 9:2621-4. [PMID: 10498221 DOI: 10.1016/s0960-894x(99)00447-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Synthesis and in vitro activity of the enantiomers of quinolone GnRH antagonist (+/-)-1 are reported. Chiral amino alcohols were prepared from the appropriate cyclic D- or L-amino acids by the Amdt-Eistert homologation followed by reduction of the resulting esters. Incorporation of these pharmacophores was achieved via a novel Mitsunobu alkylation of 4-hydroxyquinolones. The key amine pharmacophore for binding to the rat GnRH receptor was most active in the S-configuration. Ring size was not important for potency with 4, 5, 6, and 7-membered ring amines exhibiting similar potency.
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35
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Potent, elective human beta3 adrenergic receptor agonists containing a substituted indoline-5-sulfonamide pharmacophore. Bioorg Med Chem Lett 1999; 9:1869-74. [PMID: 10406657 DOI: 10.1016/s0960-894x(99)00277-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A series of compounds possessing an N-substituted indoline-5-sulfonamide pharmacophore was prepared and evaluated for their human beta3 adrenergic receptor agonist activity. The SAR of a wide range of urea and heterocyclic substituents is discussed. 4-Octyl thiazole compound 8c was the most potent and selective compound in the series, with 2800-fold selectivity over beta1 binding and 1400-fold selectivity over beta2 binding.
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36
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L-770,644: a potent and selective human beta3 adrenergic receptor agonist with improved oral bioavailability. Bioorg Med Chem Lett 1999; 9:1251-4. [PMID: 10340609 DOI: 10.1016/s0960-894x(99)00182-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
L-770,644 (9c) is a potent and selective agonist of the human beta3 adrenergic receptor (EC50 = 13 nM). It shows good oral bioavailability in both dogs and rats (%F = 27), and is a full agonist for glycerolemia in the rhesus monkey (ED50 = 0.21 mg/kg). Based on its desirable in vitro and in vivo properties, L-770,644 was chosen for further preclinical evaluation.
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37
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Abstract
Human beta3 adrenergic receptor agonists containing 5-membered ring ureas were shown to be potent partial agonists with excellent selectivity over beta1 and beta2 binding. L-760,087 (4a) and L-764,646 (5a) (beta3 EC50 = 18 and 14 nM, respectively) stimulate lipolysis in rhesus monkeys (ED50 = 0.2 and 0.1 mg/kg, respectively) with minimal effects on heart rate. Oral absorption in dogs is improved over other urea analogs.
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38
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Human beta3 adrenergic receptor agonists containing imidazolidinone and imidazolone benzenesulfonamides. Bioorg Med Chem Lett 1999; 9:755-8. [PMID: 10201842 DOI: 10.1016/s0960-894x(99)00072-4] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The cyclopentylpropylimidazolidinone L-766,892 is a potent beta3 AR agonist (EC50 5.7 nM, 64% activation) with 420- and 130-fold selectivity over binding to the beta1 and beta2 ARs, respectively. In anesthetized rhesus monkeys, L-766,892 elicited dose-dependent hyperglycerolemia (ED50 0.1 mg/kg) with minimal effects on heart rate.
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39
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Synthesis of gem-difluoro-avermectin derivatives: potent anthelmintic and anticonvulsant agents. Bioorg Med Chem Lett 1998; 8:3643-6. [PMID: 9934486 DOI: 10.1016/s0960-894x(98)00674-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
A series of gem-difluoro-avermectin derivatives was synthesized from the corresponding ketones at positions 4", 4', 13, and 23 using diethylaminosulfur trifluoride (DAST). These fluorinated avermectins exhibit potent antiparasitic activity in a new Haemonchus contortus larval assay and are equipotent to ivermectin. In addition, 23-gem-difluoro-ivermectin displays useful anticonvulsant activity in mouse models.
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40
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Abstract
The 3-pyridylethanolamine L-757,793 is a potent beta 3 AR agonist (EC50 6.3 nM, 70% activation) with 1,300- and 500-fold selectivity over binding to the beta 1 and beta 2 ARs, respectively. L-757,793 stimulated lipolysis in rhesus monkeys (ED50 0.2 mg/kg) with a maximum response equivalent to that elicited by isoproterenol.
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41
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3-Pyridyloxypropanolamine agonists of the beta 3 adrenergic receptor with improved pharmacokinetic properties. Bioorg Med Chem Lett 1998; 8:2111-6. [PMID: 9873496 DOI: 10.1016/s0960-894x(98)00381-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Pyridyloxypropanolamines L-749,372 (8, beta 3 EC50 = 3.6 nM) and L-750,355 (29, beta 3 EC50 = 13 nM) are selective partial agonists of the human receptor, with 33% and 49% activation, respectively. Both stimulate lipolysis in rhesus monkeys (ED50 = 2 and 0.8 mg/kg, respectively), with minimal effects on heart rate. Oral bioavailability in dogs, 41% for L-749,372 and 47% for L-750,355, is improved relative to phenol analogs.
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42
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Novel chemically modified oligonucleotides provide potent inhibition of P-glycoprotein expression. J Pharmacol Exp Ther 1998; 286:419-28. [PMID: 9655887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
One major form of multiple drug resistance (MDR) to cancer therapeutic agents is mediated by overexpression of P-glycoprotein, a membrane ATPase that serves as a drug efflux pump. In humans, this protein is the product of the MDR1 gene. We have used chemically modified antisense oligonucleotides to reduce expression of P-glycoprotein in multidrug-resistant fibroblasts and colon carcinoma cells. Although several types of oligonucleotides were tested, compounds having a phosphorothioate backbone and a methoxyethoxy (ME) group at the 2' position of the ribose ring proved to have the greatest potency. Thus, phosphorothioate 2'-ME oligonucleotides directed against either the AUG codon region or the stop codon region of the MDR1 message produced substantial (50-70%) inhibition of P-glycoprotein expression at concentrations of < or = 50 nM. In addition, such treatment resulted in augmented drug uptake as measured by flow cytometry. Unmodified phosphorothioate compounds of the same sequence were active only in the micromolar range. We also tested the ability of several potential delivery agents to enhance the pharmacological effectiveness of anti-MDR1 oligonucleotides. Both commercial Lipofectin, a well known liposomal transfection agent, and a liposomal preparation based on a novel "facial amphiphile" were effective in enhancing their pharmacological effects of antisense oligonucleotides. A Starburst dendrimer, a type of cationic polymer, was also effective in oligonucleotide delivery. This report emphasizes that significant improvements in antisense pharmacology can be made through judicious use of both chemical modifications of oligonucleotides and appropriate delivery systems.
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43
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A selective human beta3 adrenergic receptor agonist increases metabolic rate in rhesus monkeys. J Clin Invest 1998; 101:2387-93. [PMID: 9616210 PMCID: PMC508828 DOI: 10.1172/jci2496] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Activation of beta3 adrenergic receptors on the surface of adipocytes leads to increases in intracellular cAMP and stimulation of lipolysis. In brown adipose tissue, this serves to up-regulate and activate the mitochondrial uncoupling protein 1, which mediates a proton conductance pathway that uncouples oxidative phosphorylation, leading to a net increase in energy expenditure. While chronic treatment with beta3 agonists in nonprimate species leads to uncoupling protein 1 up-regulation and weight loss, the relevance of this mechanism to energy metabolism in primates, which have much lower levels of brown adipose tissue, has been questioned. With the discovery of L-755,507, a potent and selective partial agonist for both human and rhesus beta3 receptors, we now demonstrate that acute exposure of rhesus monkeys to a beta3 agonist elicits lipolysis and metabolic rate elevation, and that chronic exposure increases uncoupling protein 1 expression in rhesus brown adipose tissue. These data suggest a role for beta3 agonists in the treatment of human obesity.
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Abstract
The identification of L-739,943 (8b), a potent, orally bioavailable benzolactam growth hormone secretagogue, is obtained from zwitterionic L-692,429 through modification of its amino acid side chain and replacement of the acidic 2'-tetrazole with the neutral and potency enhancing 2'-(N-methylaminocarbonylamino)methyl substituent. L-739,943 is orally active for the release of growth hormone in beagle dogs at doses as low as 0.5 mg/kg. Oral bioavailability in dogs of 8b is 24% at a dose of 2 mg/kg with a mean drug Cmax of 145 +/- 46 ng/mL. L-739,943 represents a significant breakthrough in terms of both potency and oral bioavailability as compared to the prototype benzolactam L-692,429.
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Abstract
A study of 4-acylaminobenzenesulfonamides in a cloned human beta 3 adrenergic receptor assay resulted in the discovery of n-hexylurea, L-755,507 (22). This 0.43 nM beta 3 agonist, which is > 440-fold selective over both beta 1 and beta 2 binding, is among the most potent human beta 3 agonists reported to date.
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MESH Headings
- Adrenergic beta-Agonists/chemical synthesis
- Adrenergic beta-Agonists/chemistry
- Adrenergic beta-Agonists/pharmacology
- Drug Design
- Humans
- Molecular Conformation
- Molecular Structure
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/physiology
- Receptors, Adrenergic, beta-1/drug effects
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-3
- Structure-Activity Relationship
- Sulfonamides/chemical synthesis
- Sulfonamides/chemistry
- Sulfonamides/pharmacology
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Abstract
A cloned human beta 3 adrenergic receptor assay was used to identify phenoxypropanolamine agonist 1. SAR studies led to the identification of benzenesulfonamide derivative 20, a 6.3 nM beta 3 agonist which shows 30-fold selectivity for beta 3 agonist activity over beta 1 and beta 2 receptor binding. Further refinement of this lead provided 4-bromo derivative 39, a subnanomolar agonist with 660-fold and 230-fold selectivity over beta 1 and beta 2, respectively.
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MESH Headings
- Adrenergic beta-Agonists/chemical synthesis
- Adrenergic beta-Agonists/chemistry
- Adrenergic beta-Agonists/pharmacology
- Cloning, Molecular
- Drug Design
- Humans
- Molecular Conformation
- Molecular Structure
- Propanolamines/chemical synthesis
- Propanolamines/chemistry
- Propanolamines/pharmacology
- Receptors, Adrenergic, beta/drug effects
- Receptors, Adrenergic, beta/physiology
- Receptors, Adrenergic, beta-1/drug effects
- Receptors, Adrenergic, beta-2/drug effects
- Receptors, Adrenergic, beta-3
- Recombinant Proteins/drug effects
- Recombinant Proteins/metabolism
- Stereoisomerism
- Structure-Activity Relationship
- Sulfonamides/chemical synthesis
- Sulfonamides/chemistry
- Sulfonamides/pharmacology
- Benzenesulfonamides
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Abstract
PURPOSE This study was conducted to investigate the impact of backbone modifications on the hepatobiliary disposition of oligonucleotides. METHODS The disposition of backbone-modified antisense oligonucleotides [phosphorothioate (PS) and methylphosphonate (MP)] of the same base-length and sequence (5'-TAC-GCC-AAC-AGC-TCC-3'), complementary to the codon 12 activating mutation of Ki-ras, was investigated in the isolated perfused rat liver. Livers were perfused for 2 hr: perfusate and bile concentrations were analyzed by HPLC. Hepatocellular distribution was examined by measuring the amount of radiolabeled PS oligonucleotide associated with hepatocytes and Kupffer cells. Protein binding of the PS and MP oligonucleotides was determined in rat serum by ultrafiltration. RESULTS MP oligonucleotide perfusate concentrations remained constant during the 2-hour perfusion. In contrast, PS oligonucleotide was eliminated slowly by the isolated perfused liver [CI = 1.05 +/- 0.21 mL/min; extraction ratio = 0.06 +/- 0.01]. Uptake of PS oligonucleotide by Kupffer cells appeared to exceed uptake by hepatocytes, based on standard cell separation techniques as well as confocal microscopy. The degree of protein binding in rat serum was greater for the PS oligonucleotide (79.9 +/- 2.2%) than for the MP oligonucleotide (53.0 +/- 4.7%). CONCLUSIONS Backbone modifications significantly-influence the hepatic clearance of oligonucleotides. Uncharged MP oligonucleotides are not extracted by the isolated perfused rat liver, whereas the charged PS oligonucleotide is processed more readily.
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Abstract
Eprinomectin (MK-397 or 4"-epi-acetylamino-4"-deoxy-avermectin B1) is a novel avermectin selected for development as a topical endectocide for all cattle, including lactating dairy cows. Herein, we show its anthelmintic, insecticidal and miticidal activity. To determine its anthelmintic capabilities, eprinomectin was tested topically on Jersey calves at 0.08, 0.2, or 0.5 mg kg-1 in a probe formulation against experimental infections of adult Haemonchus placei, ostertagia ostertagi, Trichostrongylus axei, T. colubriformis, Cooperia oncophora, C. punctata, Nematodirus helvetianus, Oesophagostomum radiatum and Dictyocaulus viviparus. Eprinomectin removed > or = 99% and > or = 98% of the adult stage of every species at the 0.5 and 0.2 mg kg-1 dosage levels, respectively. The lowest dosage (0.08 mg kg-1) produced maximal or near maximal efficacy against most of the adult endoparasites with the exception of T. colubriformis (87%) and C. oncophora (88%). In a separate test, eprinomectin was evaluated topically against the immature stages of species at the same dosages. Results showed > or = 99% and > or = 98% removal of the immature stages of each species at the 0.5 and 0.2 mg kg-1 dosage levels, respectively. The 0.08 mg kg-1 dosage maintained > or = 97% efficacy against 6 species with reduced activity against H. placei (42%) and N. helvetianus (66%). For ectoparasites, eprinomectin was tested topically at 0.16, 0.24, 0.32 or 0.5 mg kg-1 on mixed breed cattle naturally infested with the sucking louse, Linognathus vituli. Complete elimination of lice at all dosages was observed by day 14. Topical delivery of eprinomectin at 0.16, 0.24, 0.32 or 0.5 mg kg-1 to Holstein calves experimentally challenged with horn fly, Haematobia irritans, produced 100% efficacy to challenge by week 2 post-treatment in all dosages groups and 94% and 99% efficacy to challenge at the 0.32 and 0.5 mg kg-1 dosage groups, respectively, at week 4. Topical delivery of eprinomectin at 0.16, 0.24 or 0.5 mg kg-1 to Deutsches Fleckvieh cattle infested with mange mites, Chorioptes bovis, produced > or = 95% control at all dosages levels by day 14 post-treatment and was maintained at or near this efficacious level for the 6-week duration of the trial. No adverse reaction was observed in any animal in any of these tests. In summary, these experimental data indicate that eprinomectin is an excellent broad-spectrum endectocide for cattle and is suitable for topical delivery.
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Efficacy in sheep and pharmacokinetics in cattle that led to the selection of eprinomectin as a topical endectocide for cattle. Int J Parasitol 1996; 26:1227-35. [PMID: 9024866 DOI: 10.1016/s0020-7519(96)00122-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Eprinomectin (MK-397 or 4"-epi-acetylamino-4"-deoxy-avermectin B1) is a novel avermectin selected for development as a topical endectocide for all cattle, including lactating cows. The initial efficacy assessments were made in sheep to identify subclasses of the avermectin/milbemycins that possessed inherent activity against a spectrum of nematode parasites. This included examination of several hundred analogs each given orally to a single sheep experimentally infected with a range of parasitic nematodes. Representatives of several subclasses, most notably the 4"-epi-amino avermectin B1 subclass, were identified as possessing potent, broad-spectrum activity against the endoparasites, whereas subclasses such as those with a variety of synthetic substitutions at C-4a or oximes at C-5 were among the least potent. Eprinomectin, a member of the 4"-epi-amino subclass, possessed potent activity against the range of nematodes when tested at 0.025 mg kg-1 per os. Milk and plasma concentration profiles were also made for these and other selected avermectin/milbemycins following topical administration to lactating dairy cattle. The molecular structure of each compound had a significant effect on the milk to plasma ratio, but the ratio of each was constant over time, implying an equilibrium between the 2 compartments. Compounds that were saturated at the C-22,23 bond had milk to plasma ratios > or = 1.0, whereas those unsaturated at this bond were generally < or = 1.0. The milk to plasma ratio of eprinomectin was < or = 0.2. Therefore, not only is eprinomectin the most potent broad-spectrum avermectin/milbemycin identified to date, but it also possesses one of the lowest milk partitioning coefficients in this class of antiparasitics.
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