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1.
Internet Interv ; 27: 100491, 2022 Mar.
Article in English | MEDLINE | ID: mdl-35004185

ABSTRACT

Gambling self-exclusion programs are under-utilised and barriers to entry include shame and embarrassment with face-to-face registration, and complex and effortful procedures. The current study aimed to facilitate self-exclusion from gambling venues via an online self-directed website. A co-design approach was used to elicit key stakeholders' perspectives on required website features, functionality, and to identify variables potentially impacting on development and implementation. Semi-structured focus groups and interviews were conducted across four stakeholders (N = 25): self-exclusion end users (consumers, n = 5), gambling counsellors (n = 7), venue staff (n = 6), and policy makers (n = 7). Overall, stakeholder perspectives were consistent with content analysis indicating the importance of website user-friendliness, flexibility, supportiveness, and trustworthiness. Importantly, these attributes were linked to target end users': perceived vulnerabilities, diverse backgrounds and individual expectations. Participants believed that the entire self-exclusion process should be conducted online, including identity verification, whilst expecting high-level data security measures to protect their personal privacy. A separate webpage was also suggested containing relevant information and links to additional help services, such as counselling. This study describes an adaptable co-design framework for developing a usable and acceptable self-exclusion website. Future studies should empirically test system usability and acceptability to refine and maximise system uptake upon implementation. Findings may have broader implications for digital health intervention design.

2.
J Med Microbiol ; 68(10): 1445-1454, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31429817

ABSTRACT

Purpose. Clostridium difficile spores are extremely resilient to high temperatures. Sublethal temperatures are associated with the 'reactivation' of dormant spores, and are utilized to maximize C. difficile spore recovery. Spore eradication is of vital importance to the food industry. The current study seeks to elucidate the transient and persisting effects of heating C. difficile spores at various temperatures.Methods. Spores of five C. difficile strains of different ribotypes (001, 015, 020, 027 and 078) were heated at 50, 60 and 70-80 °C for 60 min in phosphate-buffered saline (PBS) and enumerated at 0, 15, 30, 45 and 60 min. GInaFiT was used to model the kinetics of spore inactivation. In subsequent experiments, spores were transferred to enriched brain heart infusion (BHI) broths after 10 min of 80 °C heat treatment in PBS; samples were enumerated at 90 min and 24 h.Results. The spores of all strains demonstrated log-linear inactivation with tailing when heated for 60 min at 80 °C [(x̄=7.54±0.04 log10 vs 4.72±0.09 log10 colony-forming units (c.f.u.) ml- 1; P<0.001]. At 70 °C, all strains except 078 exhibited substantial decline in recovery over 60 min. Interestingly, 50 °C heat treatment had an inhibitory effect on 078 spore recovery at 0 vs 60 min (7.61±0.06 log10 c.f.u. ml- 1 vs 6.13±0.05 log10 c.f.u. ml- 1; P<0.001). Heating at 70/80 °C inhibited the initial germination and outgrowth of both newly produced and aged spores in enriched broths. This inhibition appeared to be transient; after 24 h vegetative counts were higher in heat-treated vs non-heat-treated spores (x̄=7.65±0.04 log10 c.f.u. ml- 1 vs 6.79±0.06 log10 c.f.u. ml- 1; P<0.001).Conclusions. The 078 spores were more resistant to the inhibitory effects of higher temperatures. Heat initially inhibits spore germination, but the subsequent outgrowth of vegetative populations accelerates after the initial inhibitory period.


Subject(s)
Clostridioides difficile/growth & development , Spores, Bacterial/chemistry , Clostridioides difficile/chemistry , Clostridioides difficile/classification , Clostridioides difficile/physiology , Hot Temperature , Humans , Kinetics , Microbial Viability , Ribotyping , Spores, Bacterial/growth & development , Spores, Bacterial/physiology
3.
Anaerobe ; 54: 169-171, 2018 Dec.
Article in English | MEDLINE | ID: mdl-30292821

ABSTRACT

Biofilm-derived spores of strains of four ribotypes (001, 020, 027 & 078) of Clostridioides (Clostridium) difficile were found to exhibit increased thermotolerance compared to spores produced in planktonic culture. In addition, 'thick' and 'thin' exosporium morphotypes described previously were visualised by electron microscopy in both biofilm and planktonic spores.


Subject(s)
Biofilms , Clostridioides difficile/physiology , Spores, Bacterial/chemistry , Clostridioides difficile/chemistry , Clostridioides difficile/growth & development , Clostridioides difficile/ultrastructure , Hot Temperature , Microscopy, Electron, Transmission , Spores, Bacterial/growth & development , Spores, Bacterial/physiology , Spores, Bacterial/ultrastructure , Thermotolerance
4.
Anaerobe ; 50: 38-43, 2018 Apr.
Article in English | MEDLINE | ID: mdl-29408598

ABSTRACT

BACKGROUND: A variety of supplemented solid media are used within Clostridium difficile research to optimally recover spores. Our study sought to investigate different media and additives, providing a method of optimised C. difficile spore recovery. Additionally, due to the results observed in the initial experiments, the inhibitory effects of three amino acids (glycine, l-histidine &l-phenylalanine) on C. difficile spore outgrowth were investigated. METHODS: Spores of five C. difficile strains (PCR ribotypes 001,015,020,027,078) were recovered on two commonly used solid media (BHI & CCEY, or cycloserine-cefoxitin egg yolk) supplemented with various concentrations of germinants (taurocholate, glycine & lysozyme). Agar-incorporation minimum inhibitory concentration (MIC) testing was carried out for glycine and taurocholate on vegetative cells and spores of all five strains. Additionally a BHI broth microassay method was utilised to test the growth of C. difficile in the presence of increasing concentrations (0,1,2,3,4%) of three amino acids (glycine,l-histidine,l-phenyalanine). RESULTS: CCEY agar alone and BHI supplemented with taurocholate (0.1/1%) provided optimal recovery for C. difficile spores. Glycine was inhibitory to spore recovery at higher concentrations, although these varied between the two media used. In agar-incorporated MIC testing, glycine concentrations higher than 2% (20 g/L) were inhibitory to both C. difficile spore and vegetative cell growth versus the control (mean absorbance = 0.33 ±â€¯0.02 vs 0.12 ±â€¯0.01) (P < 0.001). This indicates a potential mechanism whereby glycine interferes with vegetative cell growth. Further microbroth testing provided evidence of inhibition by two amino acids other than glycine, l-histidine and l-phenylalanine. CONCLUSIONS: We provide two media for optimal recovery of C. difficile spores (CCEY alone and BHI supplemented with 0.1/1% taurocholate). CCEY is preferred for isolation from faecal samples. For pure cultures, either CCEY or supplemented BHI agar are appropriate. The inhibitory nature of three amino acids (glycine,l-histidine,l-phenylalanine) to C. difficile vegetative cell proliferation is also highlighted.


Subject(s)
Clostridioides difficile/physiology , Culture Media , Spores, Bacterial , Agar , Amino Acids/chemistry , Amino Acids/pharmacology , Clostridioides difficile/drug effects , Culture Media/chemistry , Culture Media/pharmacology , Microbial Sensitivity Tests , Spores, Bacterial/drug effects
5.
Clin Microbiol Infect ; 24(5): 476-482, 2018 May.
Article in English | MEDLINE | ID: mdl-29208562

ABSTRACT

BACKGROUND: Recurrent Clostridium difficile infection (rCDI) places a huge economic and practical burden on healthcare facilities. Furthermore, rCDI may affect quality of life, leaving patients in an rCDI cycle and dependant on antibiotic therapy. AIMS: To discuss the importance of microbiologic factors in the development of rCDI. SOURCES: Literature was drawn from a search of PubMed from 2000 onwards with the search term 'recurrent Clostridium difficile infection' and further references cited within these articles. CONTENT: Meta-analyses and systematic reviews have shown that CDI and rCDI risk factors are similar. Development of rCDI is attendant on many factors, including immune status or function, comorbidities and concomitant treatments. Studies suggest that poor bacterial diversity is correlated with clinical rCDI. Narrow-spectrum gut microflora-sparing antimicrobials (e.g. surotomycin, cadazolid, ridinilazole) are in development for CDI treatment, while microbiota therapeutics (faecal microbiota transplantation, nontoxigenic C. difficile, stool substitutes) are increasingly being explored. rCDI can only occur when viable C. difficile spores are present, either within the gut lumen after infection or when reacquired from the environment. C. difficile spore germination can be influenced by gut environmental factors resulting from dysbiosis, and spore outgrowth may be affected stage by some antimicrobials (e.g. fidaxomicin, ramoplanin, oritavancin). IMPLICATIONS: rCDI is a significant challenge for healthcare professionals, requiring a multifaceted approach; optimized infection control to minimize reinfection; C. difficile-targeted antibiotics to minimize dysbiosis; and gut microflora restoration to promote colonization resistance. These elements should be informed by our understanding of the microbiologic factors involved in both C. difficile itself and the gut microbiome.


Subject(s)
Clostridioides difficile , Clostridium Infections/microbiology , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/therapeutic use , Clostridioides difficile/classification , Clostridioides difficile/genetics , Clostridium Infections/diagnosis , Clostridium Infections/therapy , Fecal Microbiota Transplantation/methods , Gastrointestinal Microbiome , Humans , Microbial Viability/drug effects , Recurrence , Risk Factors , Spores, Bacterial/drug effects , Superinfection
6.
J Neurosci Methods ; 262: 85-92, 2016 Mar 15.
Article in English | MEDLINE | ID: mdl-26820902

ABSTRACT

BACKGROUND: The place escape/avoidance paradigm (PEAP) has been used to assess the affective component of pain in rats. Using the Complete Freund's Adjuvant (CFA) model of inflammatory pain, the current study aimed at developing a mouse version of PEAP and investigating the relation between PEAP and other behavioural responses, namely anxiety-like behaviour, locomotor activity, and hedonic state. NEW METHOD: A novel paradigm assessing the affective component of pain in mice was developed by modifying the setup known from rat studies: Animals were forced to stay 2 × 5 min in the light and the dark area of a box while being stimulated with a suprathreshold filament on the untreated or treated paw, respectively. This was followed by a 30-min test with unrestricted movement. Anxiety-like behaviour, locomotor activity, and hedonic state were assessed with the elevated zero maze (EZM), an open field setup, and a saccharin preference test, respectively, and correlated with the PEAP behaviour to examine potentially confounding parameters of the novel paradigm. RESULTS: In the PEAP, CFA-treated animals spent more time in the light area. CFA also increased anxiety-like behaviour significantly, whereas locomotor activity was unaffected. A significant, albeit modest, reduction in saccharin preference was observed. PEAP responses showed no significant correlations with any other behavioural measure. COMPARISON WITH EXISTING METHOD AND CONCLUSIONS: The PEAP results suggest that this paradigm might be successfully applied in mice to study affective pain. CFA treatment was associated with increased anxiety-like behaviour and anhedonia; however, this appeared unrelated to the PEAP responses.


Subject(s)
Anxiety Disorders/etiology , Avoidance Learning/physiology , Disease Models, Animal , Inflammation/complications , Pain , Analysis of Variance , Animals , Anxiety Disorders/diagnosis , Female , Food Preferences , Freund's Adjuvant/toxicity , Hyperalgesia/physiopathology , Inflammation/chemically induced , Locomotion/drug effects , Locomotion/physiology , Maze Learning/physiology , Mice , Mice, Inbred C57BL , Pain/diagnosis , Pain/etiology , Pain/psychology , Pain Measurement , Pain Threshold/physiology , Saccharin/administration & dosage , Sweetening Agents/administration & dosage , Time Factors
7.
Leukemia ; 21(11): 2332-43, 2007 Nov.
Article in English | MEDLINE | ID: mdl-17625604

ABSTRACT

Gene expression profiling of diffuse large B-cell lymphoma (DLBCL) has revealed biologically and prognostically distinct subgroups: germinal center B-cell-like (GCB), activated B-cell-like (ABC) and primary mediastinal (PM) DLBCL. The BCL6 gene is often translocated and/or mutated in DLBCL. Therefore, we examined the BCL6 molecular alterations in these DLBCL subgroups, and their impact on BCL6 expression and BCL6 target gene repression. BCL6 translocations at the major breakpoint region (MBR) were detected in 25 (18.8%) of 133 DLBCL cases, with a higher frequency in the PM (33%) and ABC (24%) subgroups than in the GCB (10%) subgroup. Translocations at the alternative breakpoint region (ABR) were detected in five (6.4%) of 78 DLBCL cases, with three cases in ABC and one case each in the GCB and the unclassifiable subgroups. The translocated cases involved IgH and non-IgH partners in about equal frequency and were not associated with different levels of BCL6 mRNA and protein expression. BCL6 mutations were detected in 61% of DLBCL cases, with a significantly higher frequency in the GCB and PM subgroups (>70%) than in the ABC subgroup (44%). Exon-1 mutations were mostly observed in the GCB subgroup. The repression of known BCL6 target genes correlated with the level of BCL6 mRNA and protein expression in GCB and ABC subgroups but not with BCL6 translocation and intronic mutations. No clear inverse correlation between BCL6 expression and p53 expression was observed. Patients with higher BCL6 mRNA or protein expression had a significantly better overall survival. The biological role of BCL6 in translocated cases where repression of known target genes is not demonstrated is intriguing and warrants further investigation.


Subject(s)
DNA-Binding Proteins/biosynthesis , Lymphoma, Large B-Cell, Diffuse/genetics , Mutation , DNA Mutational Analysis , Exons , Gene Expression Profiling , Gene Expression Regulation, Neoplastic , Humans , In Situ Hybridization, Fluorescence , Introns , Lymphoma, Large B-Cell, Diffuse/metabolism , Models, Genetic , Prognosis , Proto-Oncogene Proteins c-bcl-6 , RNA, Messenger/metabolism , Time Factors , Translocation, Genetic , Treatment Outcome
8.
Ann Occup Hyg ; 50(7): 717-29, 2006 Oct.
Article in English | MEDLINE | ID: mdl-16984945

ABSTRACT

Pesticide smoke generating products are widely used by amateurs and professionals but there is little published information available about their burn and deposition characteristics to enable the risks associated with using these devices to be assessed. This paper investigates their burn characteristics, deposition patterns, pesticide air concentrations and potential exposure to operators. Thirteen firings were carried out in different spaces with different ventilation conditions. Three types of devices were investigated: dicloran, permethrin and red dye. Pesticide air concentrations increased after firing, reaching a maximum determined by the room volume in approximately 10 min and decreasing exponentially as a result of ventilation and deposition. Ejected pesticide was present in the aerosol phase but there were only occasional traces of vapour. Settlement of pesticide was affected by surface orientation, height, sampling material and the pesticide-to-space volume ratio. The manufacturer's recommended treatment period for dicloran of 4 h followed by half an hour of ventilation may be insufficient to reduce pesticide to safe levels for re-entry under very calm conditions.


Subject(s)
Air Pollutants/analysis , Pesticides/analysis , Smoke/analysis , Environmental Monitoring/methods , Humans , Particle Size , Ventilation
9.
Breast ; 14(3): 224-9, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15927831

ABSTRACT

BACKGROUND: Conservative breast surgery with postoperative radiotherapy and appropriate systemic therapy is associated with similar outcomes when compared with mastectomy. The reported 5 year local recurrence rate varies between 3% and 15%. We prefer a more conservative 'complete' local excision rather than 'wide' local excision combined with post-operative radical radiotherapy and tumour bed boost with the aim of achieving optimal cosmesis. AIMS: Our review was undertaken to assess whether or not this 'ultra' conservative approach was compromising long-term local control. METHODS: Case notes and pathology reports of patients who underwent conservative surgery for breast cancer from January 1983 to February 2001 were accessed for this audit. Patient demographic data and tumour characteristics were noted. The primary outcome data were the number of local recurrences following invasive breast cancer at 5 and 10 years and the distance from the tumour to the closest margin of excision. RESULTS: At 5 and 10 years there were 16/451 and 5/124 local recurrences, with a local recurrence rate of 3.5% (95% CI, 1.7-4.7%) and 4.1% (95% CI, 0.47-6.5%), respectively. Complete data with regards to the closest histological margin of excision were available in 423 patients. One hundred and sixty-five patients (39%) had their tumours excised with a distance of less than 1 mm to the closest margin. Nearly, all tumours (97.8%) were excised with the distance to the closest margin less than 1 cm and 81% with 5 mm or less. CONCLUSION: It is possible to achieve low local recurrence rates after very conservative surgery for breast cancer when this is combined with radical radiotherapy and an additional tumour bed boost.


Subject(s)
Breast Neoplasms/pathology , Breast Neoplasms/surgery , Mastectomy, Segmental , Neoplasm Invasiveness , Neoplasm Recurrence, Local , Adult , Aged , Aged, 80 and over , Breast Neoplasms/radiotherapy , Combined Modality Therapy , Female , Humans , Medical Audit , Middle Aged , Radiotherapy, Adjuvant , Retrospective Studies
12.
J Med Chem ; 44(26): 4501-4, 2001 Dec 20.
Article in English | MEDLINE | ID: mdl-11741469

ABSTRACT

(S)-CPW399 (2b) is a novel, potent, and subtype-selective AMPA receptor full agonist that, unlike (S)-willardiine and related compounds, in mouse cerebellar granule cells, stimulated an increase in [Ca(2+)](i), and induced neuronal cell death in a time- and concentration-dependent manner. Compound 2b appears to be a weakly desensitizing, full agonist at AMPA receptors and therefore represents a new pharmacological tool to investigate the role of AMPA receptors in excitotoxicity and their molecular mechanisms of desensitization.


Subject(s)
Alanine/chemical synthesis , Excitatory Amino Acid Agonists/chemical synthesis , Pyrimidines/chemical synthesis , Pyrimidinones/chemical synthesis , Receptors, AMPA/agonists , Alanine/analogs & derivatives , Alanine/pharmacology , Animals , Brain/cytology , Brain/metabolism , Cell Death/drug effects , Cell Line , Electrophysiology , Excitatory Amino Acid Agonists/pharmacology , In Vitro Techniques , Ligands , Mice , Models, Molecular , Neurons/cytology , Neurons/drug effects , Oocytes/metabolism , Pyrimidines/pharmacology , Pyrimidinones/pharmacology , Radioligand Assay , Rats , Receptors, AMPA/metabolism , Receptors, AMPA/physiology , Recombinant Proteins/metabolism , Stereoisomerism , Xenopus laevis
13.
J Neurosci Res ; 65(3): 267-77, 2001 Aug 01.
Article in English | MEDLINE | ID: mdl-11494361

ABSTRACT

alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R)-mediated neurotoxicity was studied in relation to subunit expression and the presence of Ca(2+)-permeable receptor channels. AMPA-mediated toxicity had two components: 1) a direct AMPA-R-mediated component, which was not due to Ca(2+) influx through voltage-gated Ca(2+) channels, reversal of the Na(+)/Ca(2+) exchanger or release of calcium from dantrolene-sensitive intracellular Ca(2+) stores, and 2) a minor, indirect component involving activation of NMDA receptor channels, because of glutamate release and removal of the Mg(2+) block of the NMDA receptor on AMPA-R stimulation. The involvement of Ca(2+) influx through AMPA-R was also examined. The number of neurons possessing Ca(2+)-permeable AMPA-R increased during culture development, concurrently with an increasing susceptibility for AMPA-induced toxicity during development. GluR2(R) levels also increased during development, and channel blockers of Ca(2+)-permeable AMPA-R lacking the GluR2(R) subunit (spermine and philanthotoxin) failed to prevent neurotoxicity or increases in [Ca(2+)](i). Thus, the direct AMPA-R-mediated toxicity may be explained by initiation of cell death by Ca(2+) fluxing through AMPA-R containing GluR2(R). The components of direct AMPA-R-mediated toxicity are proposed to be 1) toxicity mediated by GluR2(R)-lacking AMPA-R and 2) toxicity mediated by low-Ca(2+)-permeability AMPA-R containing GluR2(R).


Subject(s)
Calcium Channels/drug effects , Calcium Signaling/drug effects , Calcium/metabolism , Cerebral Cortex/cytology , Excitatory Amino Acid Agonists/toxicity , Nerve Tissue Proteins/drug effects , Neurons/drug effects , Receptors, AMPA/physiology , Sodium Channels/drug effects , Sodium/metabolism , alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/toxicity , Animals , Apoptosis/drug effects , Benzothiadiazines/pharmacology , Calcium Channel Blockers/pharmacology , Calcium Channels/genetics , Calcium Channels/metabolism , Cells, Cultured , Dizocilpine Maleate/pharmacology , Excitatory Amino Acid Antagonists/pharmacology , Flunarizine/pharmacology , Gene Expression Regulation, Developmental , Ion Channel Gating/drug effects , Lanthanum/pharmacology , Macromolecular Substances , Mice , Nerve Tissue Proteins/genetics , Nerve Tissue Proteins/metabolism , Neurons/metabolism , Neuroprotective Agents/pharmacology , Nifedipine/pharmacology , Polyamines/pharmacology , Protein Subunits , Receptors, AMPA/biosynthesis , Receptors, AMPA/genetics , Sodium Channels/genetics , Sodium Channels/metabolism , Sodium-Calcium Exchanger/metabolism , Spermine/pharmacology , Tetrodotoxin/pharmacology , omega-Conotoxins/pharmacology
14.
Am J Pathol ; 159(2): 411-5, 2001 Aug.
Article in English | MEDLINE | ID: mdl-11485898

ABSTRACT

Inflammatory myofibroblastic tumor (IMT) is a rare, but distinctive mesenchymal neoplasm composed of fascicles of bland myofibroblasts admixed with a prominent inflammatory component. Genetic studies of IMTs have demonstrated chromosomal abnormalities of 2p23 and rearrangement of the anaplastic lymphoma kinase (ALK) gene locus. In a subset of IMTs, the ALK C-terminal kinase domain is fused with a tropomyosin N-terminal coiled-coil domain. In the current study, fusion of ALK with the clathrin heavy chain (CTLC) gene localized to 17q23 was detected in two cases of IMT. One of these cases exhibited a 2;17 translocation in addition to other karyotypic anomalies [46,XX,t(2;17)(p23;q23),add(16)(q24)].


Subject(s)
Chromosomes, Human, Pair 2 , Granuloma, Plasma Cell/genetics , Head and Neck Neoplasms/genetics , Oncogene Proteins, Fusion/genetics , Pelvic Neoplasms/genetics , Protein-Tyrosine Kinases/genetics , Adult , Amino Acid Sequence , Anaplastic Lymphoma Kinase , Base Sequence , Child, Preschool , Chromosome Mapping , Clathrin/genetics , Female , Gene Rearrangement , Granuloma, Plasma Cell/pathology , Head and Neck Neoplasms/pathology , Humans , In Situ Hybridization, Fluorescence , Karyotyping , Male , Pelvic Neoplasms/pathology , Receptor Protein-Tyrosine Kinases/genetics , Reverse Transcriptase Polymerase Chain Reaction
15.
Am J Surg Pathol ; 25(5): 684-7, 2001 May.
Article in English | MEDLINE | ID: mdl-11342784

ABSTRACT

The cytogenetic findings for two epithelioid hemangioendotheliomas are reported. An identical chromosomal translocation involving chromosomes 1 and 3 [t(1;3)(p36.3;q25)] was detected in both cases of epithelioid hemangioendothelioma, possibly representing a characteristic rearrangement for this histopathologic entity. The presence of clonal karyotypic abnormalities supports a neoplastic origin for the epithelioid variant of hemangioendothelioma. Identification of the 1;3 translocation may be useful diagnostically. Should additional studies confirm these data, this could lead to the identification of the gene(s) central to this neoplastic process.


Subject(s)
Chromosomes, Human, Pair 1 , Chromosomes, Human, Pair 3 , Hemangioendothelioma, Epithelioid/genetics , Liver Neoplasms/genetics , Soft Tissue Neoplasms/genetics , Translocation, Genetic , Adult , Biomarkers, Tumor/analysis , Clone Cells , Female , Hemangioendothelioma, Epithelioid/chemistry , Hemangioendothelioma, Epithelioid/pathology , Humans , Immunohistochemistry , Karyotyping , Liver Neoplasms/chemistry , Liver Neoplasms/pathology , Middle Aged , Neoplasm Proteins/analysis , Platelet Endothelial Cell Adhesion Molecule-1/analysis , Soft Tissue Neoplasms/chemistry , Soft Tissue Neoplasms/pathology
16.
J Neurosci ; 21(9): 3052-62, 2001 May 01.
Article in English | MEDLINE | ID: mdl-11312290

ABSTRACT

Although GluR1(o) and GluR3(o) are homologous at the amino acid level, GluR3(o) desensitizes approximately threefold faster than GluR1(o). By creating chimeras of GluR1(o) and GluR3(o) and point amino acid exchanges in their S2 regions, two residues were identified to be critical for GluR1(o) desensitization: Y716 and the R/G RNA-edited site, R757. With creation of the double-point mutant (Y716F, R757G)GluR1(o), complete exchange of the desensitization rate of GluR1(o) to that of GluR3(o) was obtained. In addition, both the potency and affinity of the subtype-selective agonist bromohomoibotenic acid were exchanged by the Y716F mutation. A model is proposed of the AMPA receptor binding site whereby a hydrogen-bonding matrix of water molecules plays an important role in determining both ligand affinity and receptor desensitization properties. Residues Y716 in GluR1 and F728 in GluR3 differentially interact with this matrix to affect the binding affinity of some ligands, providing the possibility of developing subtype-selective compounds.


Subject(s)
Amino Acid Substitution/genetics , Ion Channel Gating/physiology , Receptors, AMPA/genetics , Receptors, AMPA/metabolism , Recombinant Fusion Proteins/genetics , Animals , Binding Sites/drug effects , Binding Sites/genetics , Binding, Competitive/drug effects , Binding, Competitive/genetics , Cells, Cultured , Dose-Response Relationship, Drug , Excitatory Amino Acid Agonists/pharmacology , Glutamic Acid/metabolism , Glutamic Acid/pharmacology , Hydrogen Bonding , Ibotenic Acid/analogs & derivatives , Ibotenic Acid/pharmacology , Ion Channel Gating/drug effects , Ligands , Microinjections , Models, Molecular , Mutagenesis, Site-Directed , Oocytes/cytology , Oocytes/metabolism , Patch-Clamp Techniques , Recombinant Fusion Proteins/agonists , Recombinant Fusion Proteins/metabolism , Structure-Activity Relationship , Water/metabolism , Xenopus laevis
17.
Neurochem Int ; 38(7): 581-92, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11290383

ABSTRACT

Two gamma-aminobutyric acid(A) (GABA(A)) receptor chimeras were designed in order to elucidate the structural requirements for GABA(A) receptor desensitization and assembly. The (alpha1/gamma2) and (gamma2/alpha1) chimeric subunits representing the extracellular N-terminal domain of alpha1 or gamma2 and the remainder of the gamma2 or alpha1 subunits, respectively, were expressed with beta2 and beta2gamma2 in Spodoptera frugiperda (Sf-9) cells using the baculovirus expression system. The (alpha1/gamma2)beta2 and (alpha1/gamma2)beta2gamma2 but not the (gamma2/alpha1)beta2 and (gamma2/alpha1)beta2gamma2 subunit combinations formed functional receptor complexes as shown by whole-cell patch-clamp recordings and [3H]muscimol and [3H]flunitrazepam binding. Moreover, the surface immunofluorescence staining of Sf-9 cells expressing the (alpha1/gamma2)-containing receptors was pronounced, as opposed to the staining of the (gamma2/alpha1)-containing receptors, which was only slightly higher than background. To explain this, the (alpha1/gamma2) and (gamma2/alpha1) chimeras may act like alpha1 and gamma2 subunits, respectively, indicating that the extracellular N-terminal segment is important for assembly. However, the (alpha1/gamma2) chimeric subunit had characteristics different from the alpha1 subunit, since the (alpha1/gamma2) chimera gave rise to no desensitization after GABA stimulation in whole-cell patch-clamp recordings, which was independent of whether the chimera was expressed in combination with beta2 or beta2gamma2. Surprisingly, the (alpha1/gamma2)(gamma2/alpha1)beta2 subunit combination did desensitize, indicating that the C-terminal segment of the alpha1 subunit may be important for desensitization. Moreover, desensitization was observed for the (alpha1/gamma2)beta2gamma2 receptor with respect to the direct activation by pentobarbital. This suggests differences in the mechanism of channel activation for pentobarbital and GABA.


Subject(s)
Receptors, GABA-A/metabolism , Recombinant Fusion Proteins/metabolism , Animals , Cell Line , Rats , Receptors, GABA-A/chemistry , Recombinant Fusion Proteins/chemistry , Spodoptera
18.
Eur Respir J ; 16(4): 673-6, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11106211

ABSTRACT

Spirometry and peak flow measurements traditionally depend on different forced expiratory manoeuvres and have usually been performed on separate, dedicated equipment. As spirometry becomes more widely used in primary care settings, the authors wished to determine whether there was a systematic difference between peak expiratory flow (PEF) derived from a short sharp exhalation (PEF manoeuvre) and from a full forced vital capacity (FVC) manoeuvre, using the same turbine spirometer (Microloop, Micro Medical, Kent, UK). Eighty children (38 with current asthma) aged 7-16 yrs were asked to perform 2 blocks of PEF and FVC manoeuvres, the order being randomly assigned. PEF obtained from a peak flow manoeuvre (PEFPF) was significantly greater than that from a forced vital capacity manoeuvre (PEFVC) in both healthy (group mean difference 20 L x min(-1); p<0.001) and asthmatic children (group mean difference 9 L.min(-1); p<0.004). For clinical purposes, a mean difference of about 3% for children with asthma is of no practical significance, and peak expiratory flow data can usefully be obtained during spirometric recordings.


Subject(s)
Asthma/physiopathology , Peak Expiratory Flow Rate/physiology , Spirometry/instrumentation , Vital Capacity/physiology , Adolescent , Case-Control Studies , Child , Female , Forced Expiratory Volume/physiology , Humans , Male
19.
Int J Drug Policy ; 11(6): 423-435, 2000 Dec 01.
Article in English | MEDLINE | ID: mdl-11099923

ABSTRACT

Britain continues to have a drug misuse health strategy that is HIV led. Because of this, little attention has been paid to other blood-borne viruses such as hepatitis. Moreover, while the provision of needle exchange schemes has been particularly successful in containing the spread of HIV, they have had less impact on the prevalence of hepatitis within IDU cohorts. Thus, it is necessary to understand more about the potential pathways through which the hepatitis viruses can be transmitted. One way of achieving this is to assess the propensity of IDUs to share other items of injecting paraphernalia such as water and filters. In addition, it is useful to gauge the level of opinion with respect to health hazards associated with sharing such items, amongst injecting drug users. This study reports on a small pilot project initiated to assess the degree of sharing of filters and water among 40 needle exchange service users in Worcestershire. Results based on questionnaires show that sharing of water and filters is very high within the sample group. Indeed, only 10% of clients reported never sharing either water or filters. The study also demonstrates that although injectors are aware of the health risks associated with sharing (including hepatitis transmission), they continue to participate in high risk sharing activities. Moreover, the majority of IDUs questioned have a mis-conception with respect to the most hygienic sources of water for injecting. For example, only 10% consider sterile water to be the most hygienic source for injecting, with >70% considering tap water in one form or another to be safe. The study is important because it highlights the value of providing sterile water and filters to IDUs to meet their basic and fundamental needs. It is hoped that the findings from this small project will have a wider transferability to other IDU cohorts throughout the UK and beyond.

20.
Neuroreport ; 11(12): 2643-8, 2000 Aug 21.
Article in English | MEDLINE | ID: mdl-10976936

ABSTRACT

The lack of subtype-selective compounds for AMPA receptors (AMPA-R) led us to search for compounds with such selectivity. Homoibotenic acid analogues were investigated at recombinant GluR1o, GluR2o(R), GluR3o and GluR1o + 3o receptors expressed in Sf9 insect cells and affinities determined in [3H]AMPA radioligand binding experiments. (S)-4-bromohomoibotenic acid (BrHIBO) exhibited a 126-fold selectivity for GluR1o compared to GluR3o. Xenopus laevis oocytes were used to express functional homomeric and heteromeric recombinant AMPA-R and to determine BrHIBO potency (EC50) at these channels. (R,S)-BrHIBO exhibited a 37-fold selectivity range amongst the AMPA-R. It is hoped that BrHIBO can be used as a lead structure for the development of other subtype-selective compounds.


Subject(s)
Receptors, AMPA/agonists , Receptors, AMPA/metabolism , Animals , Binding, Competitive , Cell Line , Dose-Response Relationship, Drug , Female , Ibotenic Acid/analogs & derivatives , Ibotenic Acid/metabolism , Insecta/cytology , Ion Channels/metabolism , Oocytes , Protein Isoforms/agonists , Protein Isoforms/metabolism , Recombinant Proteins/metabolism , Xenopus laevis
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