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Tye S, Ronson GE, Morris JR. A fork in the road: Where homologous recombination and stalled replication fork protection part ways. Semin Cell Dev Biol 2021; 113:14-26. [PMID: 32653304 PMCID: PMC8082280 DOI: 10.1016/j.semcdb.2020.07.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/06/2020] [Accepted: 07/06/2020] [Indexed: 12/14/2022]
Abstract
In response to replication hindrances, DNA replication forks frequently stall and are remodelled into a four-way junction. In such a structure the annealed nascent strand is thought to resemble a DNA double-strand break and remodelled forks are vulnerable to nuclease attack by MRE11 and DNA2. Proteins that promote the recruitment, loading and stabilisation of RAD51 onto single-stranded DNA for homology search and strand exchange in homologous recombination (HR) repair and inter-strand cross-link repair also act to set up RAD51-mediated protection of nascent DNA at stalled replication forks. However, despite the similarities of these pathways, several lines of evidence indicate that fork protection is not simply analogous to the RAD51 loading step of HR. Protection of stalled forks not only requires separate functions of a number of recombination proteins, but also utilises nucleases important for the resection steps of HR in alternative ways. Here we discuss how fork protection arises and how its differences with HR give insights into the differing contexts of these two pathways.
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Affiliation(s)
- Stephanie Tye
- Section of Structural and Synthetic Biology, Department of Infectious Disease, Imperial College London, London, SW7 2AZ, UK
| | - George E Ronson
- University of Birmingham, College of Medical Dental Schools, Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK
| | - Joanna R Morris
- University of Birmingham, College of Medical Dental Schools, Institute of Cancer and Genomics Sciences, Birmingham Centre for Genome Biology, Vincent Drive, Edgbaston, Birmingham, B15 2TT, UK.
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Daza-Martin M, Starowicz K, Jamshad M, Tye S, Ronson GE, MacKay HL, Chauhan AS, Walker AK, Stone HR, Beesley JFJ, Coles JL, Garvin AJ, Stewart GS, McCorvie TJ, Zhang X, Densham RM, Morris JR. Isomerization of BRCA1-BARD1 promotes replication fork protection. Nature 2019; 571:521-527. [PMID: 31270457 DOI: 10.1038/s41586-019-1363-4] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 06/03/2019] [Indexed: 01/01/2023]
Abstract
The integrity of genomes is constantly threatened by problems encountered by the replication fork. BRCA1, BRCA2 and a subset of Fanconi anaemia proteins protect stalled replication forks from degradation by nucleases, through pathways that involve RAD51. The contribution and regulation of BRCA1 in replication fork protection, and how this role relates to its role in homologous recombination, is unclear. Here we show that BRCA1 in complex with BARD1, and not the canonical BRCA1-PALB2 interaction, is required for fork protection. BRCA1-BARD1 is regulated by a conformational change mediated by the phosphorylation-directed prolyl isomerase PIN1. PIN1 activity enhances BRCA1-BARD1 interaction with RAD51, thereby increasing the presence of RAD51 at stalled replication structures. We identify genetic variants of BRCA1-BARD1 in patients with cancer that exhibit poor protection of nascent strands but retain homologous recombination proficiency, thus defining domains of BRCA1-BARD1 that are required for fork protection and associated with cancer development. Together, these findings reveal a BRCA1-mediated pathway that governs replication fork protection.
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Affiliation(s)
- Manuel Daza-Martin
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
- The Institute of Cancer Research, Chester Beatty Laboratories, London, UK
| | - Katarzyna Starowicz
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Mohammed Jamshad
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Stephanie Tye
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
| | - George E Ronson
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Hannah L MacKay
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Anoop Singh Chauhan
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Alexandra K Walker
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Helen R Stone
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - James F J Beesley
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Jennifer L Coles
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
- Warwick Medical School, The University of Warwick, Coventry, UK
| | - Alexander J Garvin
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Grant S Stewart
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK
| | - Thomas J McCorvie
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
| | - Xiaodong Zhang
- Section of Structural Biology, Department of Medicine, Imperial College London, London, UK
| | - Ruth M Densham
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK.
| | - Joanna R Morris
- Birmingham Centre for Genome Biology and Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, UK.
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Guzov I, Pecherina E, Kozlov V, Laskina O, Sintyrina N, Ruzhanskaia A, Sedyshkina E, Gvozdik E, Tye S, Zenkina A, Kurgannikov A. Derivation of Russian reference intervals for anti-müllerian hormone (AMH) using access AMH assay. Clin Chim Acta 2019. [DOI: 10.1016/j.cca.2019.03.698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Chadwick DD, Stubbs J, Fovargue S, Anderson D, Stacey G, Tye S. Training support staff to modify fluids to appropriate safe consistencies for adults with intellectual disabilities and dysphagia: an efficacy study. J Intellect Disabil Res 2014; 58:84-98. [PMID: 23336612 DOI: 10.1111/jir.12013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 11/05/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Modifying the consistency of food and drink is a strategy commonly used in the management of dysphagia for people with intellectual disabilities (ID). People with ID often depend on others for the preparation of food and drink and therefore depend on those caregivers achieving the correct consistency to keep them safe and avoid discomfort during mealtimes. Clinical experience and prior research have demonstrated that although training can improve modification, carers often find modification difficult and potentially stressful and recommend additional support for carers. Fluid consistency is often modified through the addition of powdered thickener. This study investigates the efficacy of typical training and use of consistency guides, the Thickness Indicator Model (TIM) tubes, in helping carers to modify fluids accurately. METHOD A 3 × 3 pre-post experimental design with a control group was employed to compare the observed accuracy of modification across three groups and at three time points (pre-intervention baseline, immediately post-training intervention and 3-10 months post-training). Sixty-two paid carers who supported people with ID were recruited to participate in the study and each was randomly allocated to one of the three groups: a control group given written guidance only, a group who received typical training and written guidance and a group who received training, written guidance and the TIM tubes. RESULTS & CONCLUSIONS Typical training resulted in significantly greater carer accuracy in modifying fluid consistencies when compared with written guidance alone. Use of the TIM tubes also significantly improved accuracy in the modification of drinks compared with the group who modified with the aid of written guidance alone. At 3-10-month follow-up only the group who received typical training alongside the TIM tubes were significantly more accurate than the Written Guidance group. Further research is warranted to ascertain the effectiveness of the training and the utility of the TIM tubes in improving accuracy over a longer time scale and in individuals' usual living environments.
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Affiliation(s)
- D D Chadwick
- School of Applied Sciences, The University of Wolverhampton, Wolverhampton, UK
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Tye S, Carnie R, Chambers R, Doran CM, Matthews JJ. The surgical aspects of Role 2 Afloat. J R Nav Med Serv 2013; 99:146-148. [PMID: 24511802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The current configuration of the surgical component of the Role 2 Afloat team is described, including an outline of the equipment available. The lessons learned from a recent exercise, where a Role 2 Afloat team was deployed on RFA CARDIGAN BAY are outlined and expanded, emphasising the difficulties of providing damage control surgery in the maritime environment.
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Affiliation(s)
- S Tye
- Operating Department Practioner, MDHU Frimley Park
| | | | | | - C M Doran
- Consultant General Surgeon, MDHU Portsmouth. Surgeon Commander J J Matthews
| | - J J Matthews
- Consultant Orthopaedic Surgeon, Royal Cornwall Hospitals NHS Trust
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Atack JR, Wafford KA, Street LJ, Dawson GR, Tye S, Van Laere K, Bormans G, Sanabria-Bohórquez SM, De Lepeleire I, de Hoon JN, Van Hecken A, Burns HD, McKernan RM, Murphy MG, Hargreaves RJ. MRK-409 (MK-0343), a GABAA receptor subtype-selective partial agonist, is a non-sedating anxiolytic in preclinical species but causes sedation in humans. J Psychopharmacol 2011; 25:314-28. [PMID: 20147571 DOI: 10.1177/0269881109354927] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
MRK-409 binds to α1-, α2-, α3- and α5-containing human recombinant GABA(A) receptors with comparable high affinity (0.21-0.40 nM). However, MRK-409 has greater agonist efficacy at the α3 compared with α1 subtypes (respective efficacies relative to the full agonist chlordiazepoxide of 0.45 and 0.18). This compound readily penetrates the brain in rats and occupies the benzodiazepine site of GABA(A) receptors, measured using an in vivo [(3)H]flumazenil binding assay, with an Occ(50) of 2.2 mg/kg p.o. and a corresponding plasma EC(50) of 115 ng/mL. Behaviourally, the α3-preferring agonist efficacy profile of MRK-409 produced anxiolytic-like activity in rodent and primate unconditioned and conditioned models of anxiety with minimum effective doses corresponding to occupancies, depending on the particular model, ranging from ∼35% to 65% yet there were minimal overt signs of sedation at occupancies greater than 90%. In humans, however, safety and tolerability studies showed that there was pronounced sedation at a dose of 2 mg, resulting in a maximal tolerated dose of 1 mg. This 2 mg dose corresponded to a C(max) plasma concentration of 28 ng/mL, which, based on the rodent plasma EC(50) for occupancy of 115 ng/mL, suggested that sedation in humans occurs at low levels of occupancy. This was confirmed in human positron emission tomography studies, in which [(11)C]flumazenil uptake following a single dose of 1 mg MRK-409 was comparable to that of placebo, indicating that occupancy of GABA(A) receptor benzodiazepine binding sites by MRK-409 was below the limits of detection (i.e. <10%). Taken together, these data show that MRK-409 causes sedation in humans at a dose (2 mg) corresponding to levels of occupancy considerably less than those predicted from rodent models to be required for anxiolytic efficacy (∼35-65%). Thus, the preclinical non-sedating anxiolytic profile of MRK-409 did not translate into humans and further development of this compound was halted.
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Affiliation(s)
- J R Atack
- Neuroscience Research Centre, Merck Sharp & Dohme Research Laboratories, Harlow, UK.
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Atack JR, Hallett DJ, Tye S, Wafford KA, Ryan C, Sanabria-Bohórquez SM, Eng WS, Gibson RE, Burns HD, Dawson GR, Carling RW, Street LJ, Pike A, De Lepeleire I, Van Laere K, Bormans G, de Hoon JN, Van Hecken A, McKernan RM, Murphy MG, Hargreaves RJ. Preclinical and clinical pharmacology of TPA023B, a GABAA receptor α2/α3 subtype-selective partial agonist. J Psychopharmacol 2011; 25:329-44. [PMID: 20156926 DOI: 10.1177/0269881109354928] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In the accompanying paper we describe how MRK-409 unexpectedly produced sedation in man at relatively low levels of GABA(A) receptor occupancy (∼10%). Since it was not clear whether this sedation was mediated via the α2/α3 or α1 GABA(A) subtype(s), we characterized the properties of TPA023B, a high-affinity imidazotriazine which, like MRK-409, has partial agonist efficacy at the α2 and α3 subtype but is an antagonist at the α1 subtype, at which MRK-409 has weak partial agonism. TPA023B gave dose- and time-dependent occupancy of rat brain GABA(A) receptors as measured using an in vivo [(3)H]flumazenil binding assay, with 50% occupancy corresponding to a respective dose and plasma drug concentration of 0.09 mg/kg and 19 ng/mL, the latter of which was similar to that observed in mice (25 ng/mL) and comparable to values obtained in baboon and man using [(11)C]flumazenil PET (10 and 5.8 ng/mL, respectively). TPA023B was anxiolytic in rodent and primate (squirrel monkey) models of anxiety (elevated plus maze, fear-potentiated startle, conditioned suppression of drinking, conditioned emotional response) yet had no significant effects in rodent or primate assays of ataxia and/or myorelaxation (rotarod, chain-pulling, lever pressing), up to doses (10 mg/kg) corresponding to occupancy of greater than 99%. In man, TPA023B was well tolerated at a dose (1.5 mg) that produced occupancy of >50%, suggesting that the sedation previously seen with MRK-409 is due to the partial agonist efficacy of that compound at the α1 subtype, and highlighting the importance of antagonist efficacy at this particular GABA(A) receptor population for avoiding sedation in man.
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Affiliation(s)
- J R Atack
- Neuroscience Research Centre, Merck Sharp & Dohme Research Laboratories, Harlow, UK.
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Borody TJ, Bilkey S, Wettstein AR, Leis S, Pang G, Tye S. Anti-mycobacterial therapy in Crohn's disease heals mucosa with longitudinal scars. Dig Liver Dis 2007; 39:438-44. [PMID: 17369114 DOI: 10.1016/j.dld.2007.01.008] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2006] [Revised: 12/17/2006] [Accepted: 01/12/2007] [Indexed: 12/11/2022]
Abstract
BACKGROUND A possible causative link between Crohn's disease and Mycobacterium avium ss paratuberculosis has been suggested. AIM To report unique scarring in Crohn's disease patients treated with anti-Mycobacterium avium ss paratuberculosis therapy. PATIENTS A retrospective review of 52 patients with severe Crohn's disease was conducted. Thirty-nine patients who had at least one follow-up colonoscopy during treatment were included. METHODS Patients received rifabutin (up to 600 mg/day), clofazimine (up to 100 mg/day) and clarithromycin (up to 1 g/day) - anti-Mycobacterium avium ss paratuberculosis therapy - for 6 months to 9 years. Ramp-up dosing was used. Colonoscopies and histological analyses monitored progress. RESULTS Twenty-two patients (56.4%, 22/39) healed with unusual scarring, which appeared as branched, ribbon-like, elevated lines. In 2/6 patients (33.3%) who had > 3 years of treatment after scarring occurred, scars receded, becoming imperceptible as full healing occurred. Histologically, a marked reduction in inflammation occurred in 15/39 patients (38.5%). Of these, 6/15 patients (40%) displayed restoration of normal mucosa. Longitudinal scarring occurred in 12/15 patients (80%) with improved histology. CONCLUSIONS The presence of scarring fading to normal mucosa on anti-MAP therapy implies a more profound healing not seen with standard anti-inflammatory and immunosuppressant drugs. Longitudinal scarring and consequent healing with normal histology should become a standard treatment goal for Crohn's disease.
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Affiliation(s)
- T J Borody
- Centre for Digestive Diseases, Level 1, 229 Great North Road, Five Dock, NSW 2046, Australia.
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Chirinos JL, Brindis C, Tye S, McCarter V. Differences and similarities in sexual and contraceptive knowledge, attitudes, and behavior among Latino male adolescent students in California, United States and Lima, Peru. CAD SAUDE PUBLICA 2001; 17:833-42. [PMID: 11514864 DOI: 10.1590/s0102-311x2001000400017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
To identify the differences and similarities in sexual and contraceptive knowledge, attitudes, and behavior among Latino male adolescent students living in California and Lima. Self-administered, anonymous surveys were completed by Latino male students aged 12-19 participating in California, and by male adolescent students in four high schools in Lima. Both surveys contained similar questions allowing for comparisons regarding sexual activity and contraceptive behavior. The mean age of male students were 16 and 15 years, respectively. More California males reported having engaged in sexual intercourse (69% vs 43%. The sexual debut was 13 years in both samples. More students in California were aware of their risk of pregnancy at first sexual intercourse than in Lima (82% vs 50%). One-third of the California males reported communicating with their partner about sex and contraception to be "easy" as compared to 53% of males in Lima. More students in California reported knowing a place to obtain contraceptives if they need them (85% vs 63%), having ever gotten someone pregnant (29% vs 7%), and having fathered a child (67% vs 16%).
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Affiliation(s)
- J L Chirinos
- Instituto de Estudios de Población, Universidad Peruana Cayetano Heredia, Lima, Peru
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Tattersall FD, Rycroft W, Cumberbatch M, Mason G, Tye S, Williamson DJ, Hale JJ, Mills SG, Finke PE, MacCoss M, Sadowski S, Ber E, Cascieri M, Hill RG, MacIntyre DE, Hargreaves RJ. The novel NK1 receptor antagonist MK-0869 (L-754,030) and its water soluble phosphoryl prodrug, L-758,298, inhibit acute and delayed cisplatin-induced emesis in ferrets. Neuropharmacology 2000; 39:652-63. [PMID: 10728886 DOI: 10.1016/s0028-3908(99)00172-0] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The anti-emetic profile of the novel brain penetrant tachykinin NK1 receptor antagonist MK-0869 (L-754,030) 2-(R)-(1-(R)-(3,5-bis(trifluoromethyl)phenylethoxy)-3-(S)-(4-fluor o)phenyl-4-(3-oxo-1,2,4-triazol-5-yl)methylmorpholine and its water soluble prodrug, L-758,298, has been examined against emesis induced by cisplatin in ferrets. In a 4 h observation period, MK-0869 and L-758,298 (3 mg/kg i.v. or p.o.) inhibited the emetic response to cisplatin (10 mg/kg i.v.). The anti-emetic protection afforded by MK-0869 (0.1 mg/kg i.v.) was enhanced by combined treatment with either dexamethasone (20 mg/kg i.v.) or the 5-HT3 receptor antagonist ondansetron (0.1 mg/kg i.v.). In a model of acute and delayed emesis, ferrets were dosed with cisplatin (5 mg/kg i.p.) and the retching and vomiting response recorded for 72 h. Pretreatment with MK-0869 (4-16 mg/kg p.o.) dose-dependently inhibited the emetic response to cisplatin. Once daily treatment with MK-0869 (2 and 4 mg/kg p.o.) completely prevented retching and vomiting in all ferrets tested. Further when daily dosing began at 24 h after cisplatin injection, when the acute phase of emesis had already become established, MK-0869 (4 mg/kg p.o. at 24 and 48 h after cisplatin) prevented retching and vomiting in three out of four ferrets. These data show that MK-0869 and its prodrug, L-758,298, have good activity against cisplatin-induced emesis in ferrets and provided a basis for the clinical testing of these agents for the treatment of emesis associated with cancer chemotherapy.
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Affiliation(s)
- F D Tattersall
- Department of Pharmacology, Merck, Sharp and Dohme, Neuroscience Research Centre, Harlow, Essex, UK.
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Dawson GR, Rupniak NM, Iversen SD, Curnow R, Tye S, Stanhope KJ, Tricklebank MD. Lack of effect of CCKB receptor antagonists in ethological and conditioned animal screens for anxiolytic drugs. Psychopharmacology (Berl) 1995; 121:109-17. [PMID: 8539335 DOI: 10.1007/bf02245597] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The effects of the CCKB receptor antagonists L-365,260, CI-988 and L-740,093, a new compound with improved bioavailability and CNS penetration, were assessed for anxiolytic-like effects in three rat anxiolytic screens sensitive to benzodiazepines, the elevated plus maze (EPM), conditioned suppression of drinking (CSD) and conditioned emotional response (CER) tests. In the EPM, L-740,093 (0.1-1.0 mg/kg), L-365,260 (0.00001-10.0 mg/kg), and CI-988 (0.01-1.0 mg/kg) did not increase the time spent on the open arms of the maze or the number of entries onto the open arms. In contrast, the benzodiazepine receptor partial agonist, bretazenil (0.3-10.0 mg/kg), significantly increased both the time spent on the open arms and the number of open arm entries. In the CSD and the CER tests, L-740,093 (0.1-1.0 mg/kg) L-365,260 (0.0001-0.1 mg/kg) and CI-988 (0.01-10.0 mg/kg) failed to increase suppression ratios compared to the vehicle-treated control rats, whereas, the benzodiazepine receptor partial agonist FG 8205 (10.0 mg/kg) (CSD) and bretazenil (0.3-3.0 mg/kg) (CER) both significantly increased suppression ratios compared to vehicle-treated control rats. In addition, L-365,260 (1.0-50.0 mg/kg), CI-988 (0.1-10.0 mg/kg) and diazepam (0.1-1.0 mg/kg) were assessed in a squirrel monkey conflict procedure. Although diazepam significantly increased suppressed lever pressing rates, L-365,260 and CI-988 were without effect. The present findings provide little support for the hypothesis that CCKB receptor antagonists have anti-anxiety effects in animals.
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Affiliation(s)
- G R Dawson
- Merck, Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex, UK
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Abstract
Anxiolytic-like and antinociceptive activities of the noncompetitive NMDA receptor antagonist MK-801 (dizocilpine) were compared with sedative and ataxic side effects in primates. Administration of MK-801 (0.1 mg/kg) caused taming in cynomolgus monkeys and increased tail withdrawal latencies in squirrel monkeys; both effects were accompanied by sedation and ataxia. These findings are discussed in relation to the possible therapeutic uses of NMDA antagonists and differences in the behavioural effects of such compounds in primate and rodent species.
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Affiliation(s)
- N M Rupniak
- Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Terlings Park, Harlow, Essex, UK
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Tricklebank MD, Honoré T, Iversen SD, Kemp JA, Knight AR, Marshall GR, Rupniak NM, Singh L, Tye S, Watjen F. The pharmacological properties of the imidazobenzodiazepine, FG 8205, a novel partial agonist at the benzodiazepine receptor. Br J Pharmacol 1990; 101:753-61. [PMID: 1963808 PMCID: PMC1917729 DOI: 10.1111/j.1476-5381.1990.tb14152.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
1. The pharmacological properties of the benzodiazepine receptor ligand, FG 8205 (7-chloro-5,6-dihydro-5-methyl-6-oxo-3-(5-isopropyl-1,2,4-oxadiazol++ +-3-yl)-4H- imidazol[1,5a][1,4]benzodiazepine) have been examined. 2. FG 8205 potently displaced [3H]-flumazenil binding in rat cortical membranes with a Ki of 3.3 nM, but was inactive at 13 neurotransmitter recognition sites. 3. Consistent with a partial agonist profile, the affinity of FG 8205 for the benzodiazepine recognition site was increased in the presence of gamma-aminobutyric acid (GABA, 300 microM) by a degree (-log [IC50 in the presence of GABA/IC50 alone] = 0.34) significantly less than found for diazepam (0.46). FG 8205 also potentiated the inhibitory potency of the GABAA-receptor agonist, isoguvacine, on the hippocampal CA1 population spike and, again, the maximum shift (-log dose-ratio = 0.2) was significantly less than that seen with diazepam (0.4). 4. In anticonvulsant studies, the ED50 doses of FG 8205 and diazepam needed to antagonize seizures induced by pentylenetetrazol (PTZ) or by sound in audiogenic seizure prone mice were similar with values of 0.2-0.3 mg kg-1, i.p. However, even high doses of FG 8205 (50 mg kg-1) did not protect against seizures induced by electroshock. 5. FG 8205 released responding suppressed by footshock in a rat operant conditioned emotional response task over the dose range 0.5-50 mg kg-1 (i.p.). Similar doses of FG 8205 had a marked taming effect in cynomolgus monkeys. However, measures of sedation and ataxia (as measured by rotarod in the mouse, climbing behaviour in the rat, and by scoring arousal and co-ordination in primates) were slight and only transiently affected by FG 8205, and FG 8205 significantly antagonized the rotarod performance deficit induced by diazepam in the mouse. 6. While the potentiation by FG 8205 of the response to isoguvacine in the rat hippocampal slice and the anxiolytic-like effects of the compound in both rats and primates were reversed by the benzodiazepine receptor antagonist, flumazenil, high doses of the antagonist were able only marginally to block the protective effects of FG 8205 against seizures induced by PTZ in the mouse. 7. Thus, FG 8205 does not show the marked motor impairment characteristic of full agonists at the benzodiazepine receptor, consistent with its partial agonist profile in in vitro assay systems. Nevertheless, the compound has sufficient intrinsic activity to maintain high efficacy in anticonvulsant and anxiolytic tests.
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Affiliation(s)
- M D Tricklebank
- Merck Sharp and Dohme Research Laboratories, Neuroscience Research Centre, Harlow, Essex
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Qiu Z, Tye S. Defining the configuration space of string field theory. Phys Rev Lett 1989; 63:1203-1206. [PMID: 10040502 DOI: 10.1103/physrevlett.63.1203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Tye S. New proposal for closed-string field theory: The free-string case. Phys Rev Lett 1989; 63:1046-1049. [PMID: 10040451 DOI: 10.1103/physrevlett.63.1046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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Goldstein R, Tye S. Social work management of the Alzheimer's patient: who needs the support? Mt Sinai J Med 1987; 54:86-92. [PMID: 3494921] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Tye S. New actions for superstrings. Phys Rev Lett 1985; 55:1347-1350. [PMID: 10031795 DOI: 10.1103/physrevlett.55.1347] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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