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1.  Justification of diagnostic medical exposures: some practical issues. Report of an International Atomic Energy Agency Consultation 
The British Journal of Radiology  2012;85(1013):523-538.
The Radiation Protection of Patients Unit of the International Atomic Energy Agency (IAEA) is concerned about the effectiveness of justification of diagnostic medical exposures. Recent published work and the report of an initial IAEA consultation in the area gave grounds for such concerns. There is a significant level of inappropriate usage, and, in some cases, a poor level of awareness of dose and risk among some key groups involved. This article aims to address this.
The IAEA convened a second group of experts in November 2008 to review practical and achievable actions that might lead to more effective justification.
This report summarises the matters that this group considered and the outcome of their deliberations. There is a need for improved communication, both within professions and between professionals on one hand, and between professionals and the patients/public on the other. Coupled with this, the issue of consent to imaging procedures was revisited. The need for good evidence-based referral guidelines or criteria of acceptability was emphasised, as was the need for their global adaptation and dissemination.
Clinical audit was regarded as a key tool in ensuring that justification becomes an effective, transparent and accountable part of normal radiological practice. In summary, justification would be facilitated by the “3 As”: awareness, appropriateness and audit.
PMCID: PMC3479887  PMID: 21343316
2.  Impacts of long-term enhanced UV-B radiation on bryophytes in two sub-Arctic heathland sites of contrasting water availability 
Annals of Botany  2011;108(3):557-565.
Background and Aims
Anthropogenic depletion of stratospheric ozone in Arctic latitudes has resulted in an increase of ultraviolet-B radiation (UV-B) reaching the biosphere. UV-B exposure is known to reduce above-ground biomass and plant height, to increase DNA damage and cause accumulation of UV-absorbing compounds in polar plants. However, many studies on Arctic mosses tended to be inconclusive. The importance of different water availability in influencing UV-B impacts on lower plants in the Arctic has been poorly explored and might partially explain the observed wide variation of responses, given the importance of water in controlling bryophyte physiology. This study aimed to assess the long-term responses of three common sub-Arctic bryophytes to enhanced UV-B radiation (+UV-B) and to elucidate the influence of water supply on those responses.
Responses of three sub-Arctic bryophytes (the mosses Hylocomium splendens and Polytrichum commune and the liverwort Barbilophozia lycopodioides) to +UV-B for 15 and 13 years were studied in two field experiments using lamps for UV-B enhancement with identical design and located in neighbouring areas with contrasting water availability (naturally mesic and drier sites). Responses evaluated included bryophyte abundance, growth, sporophyte production and sclerophylly; cellular protection by accumulation of UV-absorbing compounds, β-carotene, xanthophylls and development of non-photochemical quenching (NPQ); and impacts on photosynthesis performance by maximum quantum yield (Fv /Fm) and electron transport rate (ETR) through photosystem II (PSII) and chlorophyll concentrations.
Responses were species specific: H. splendens responded most to +UV-B, with reduction in both annual growth (–22 %) and sporophyte production (–44 %), together with increased β-carotene, violaxanthin, total chlorophyll and NPQ, and decreased zeaxanthin and de-epoxidation of the xanthophyll cycle pool (DES). Barbilophozia lycopodioides responded less to +UV-B, showing increased β-carotene and sclerophylly and decreased UV-absorbing compounds. Polytrichum commune only showed small morphogenetic changes. No effect of UV-B on bryophyte cover was observed. Water availability had profound effects on bryophyte ecophysiology, and plants showed, in general, lower growth and ETR, together with a higher photoprotection in the drier site. Water availability also influenced bryophyte responses to +UV-B and, in particular, responses were less detectable in the drier site.
Impacts of UV-B exposure on Arctic bryophytes were significant, in contrast to modest or absent UV-B effects measured in previous studies. The impacts were more easily detectable in species with high plasticity such as H. splendens and less obvious, or more subtle, under drier conditions. Species biology and water supply greatly influences the impact of UV-B on at least some Arctic bryophytes and could contribute to the wide variation of responses observed previously.
PMCID: PMC3158694  PMID: 21803739
Enhanced long-term UV-B; water availability; sub-Arctic bryophytes; xanthophylls; chlorophyll fluorescence; sporophytes
3.  Allosteric regulation of the light-harvesting system of photosystem II. 
Non-photochemical quenching of chlorophyll fluorescence (NPQ) is symptomatic of the regulation of energy dissipation by the light-harvesting antenna of photosystem II (PS II). The kinetics of NPQ in both leaves and isolated chloroplasts are determined by the transthylakoid delta pH and the de-epoxidation state of the xanthophyll cycle. In order to understand the mechanism and regulation of NPQ we have adopted the approaches commonly used in the study of enzyme-catalysed reactions. Steady-state measurements suggest allosteric regulation of NPQ, involving control by the xanthophyll cycle carotenoids of a protonation-dependent conformational change that transforms the PS II antenna from an unquenched to a quenched state. The features of this model were confirmed using isolated light-harvesting proteins. Analysis of the rate of induction of quenching both in vitro and in vivo indicated a bimolecular second-order reaction; it is suggested that quenching arises from the reaction between two fluorescent domains, possibly within a single protein subunit. A universal model for this transition is presented based on simple thermodynamic principles governing reaction kinetics.
PMCID: PMC1692867  PMID: 11127991
6.  Antiprostaglandin synthetase activity of nonsteroidal anti-inflammatory drugs and gastrointestinal micro-bleeding: a comparison of flurbiprofen with benoxaprofen. 
Annals of the Rheumatic Diseases  1981;40(5):455-461.
By using 51Cr-labelled erythrocytes and 141Ce-labelled microspheres to correct for daily variations in faecal output, gastrointestinal microbleeding was measured in hospital patients with rheumatoid arthritis before and after administration of 2 propionic acid derivatives. These were flurbiprofen and benoxaprofen, respectively a potent and a weak prostaglandin synthetase inhibitor. Increased faecal blood loss occurred consistently with flurbiprofen and not with benoxaprofen. Our results provide indirect evidence for the cytoprotective effect of prostaglandins on the gastrointestinal mucosa in man. The quantitative correlation between faecal occult blood loss as measured by the above techniques and the Haemoccult slide test is also discussed.
PMCID: PMC1000780  PMID: 6796008
7.  Time course of antilisterial activity by immunologically activated murine peritoneal macrophages. 
Infection and Immunity  1983;39(2):532-539.
Murine peritoneal macrophages were rapidly rendered listericidal after exposure to lymphokine-rich supernatants (LRSs) derived from antigen-pulsed Listeria monocytogenes-immune spleen cells. A 6-h incubation period with LRSs was sufficient to induce microbicidal activity in resident macrophages. In vitro induction of macrophage listericidal activity by constant exposure to LRSs persisted for 18 h, after which time spleen cell factors were no longer capable of modifying intracellular inactivation of Listeria. Results obtained by utilizing a short assay indicated that the killing kinetics is extremely rapid, with large numbers of bacteria destroyed during the first 15 min of infection. Intracellular killing at this time appeared to be greatly dependent upon the stage of growth from which the microorganisms were harvested. Induction of bactericidal macrophages by infection of mice with a sublethal dose of virulent Listeria cells and subsequent intraperitoneal elicitation with heat-killed homologous bacteria was similarly a transient event. Macrophages harvested 18 h after antigenic challenge displayed dramatic antibacterial activity during the first 22 h in culture. After 22 h, activity was lost, and stasis was observed during the ensuing 23 h. At 68 h, macrophages were devoid of antilisterial action. Activity, however, could be recalled after incubation with LRSs.
PMCID: PMC347983  PMID: 6403458
8.  Remission of Thyrotoxicosis during Treatment with Propranolol 
British Medical Journal  1973;2(5862):332-334.
Twenty-eight thyrotoxic patients were treated with propranolol. In seven patients the drug had to be discontinued after one or two months, but in the remaining 21 clinical improvement was observed. Serial clinical studies and tests of thyroid function performed at monthly intervals showed that in four patients thyrotoxicosis remitted and all indices of thyroid function returned to normal. A fifth patient shows distinct evidence of remission with the 20-minute 132I uptake falling to normal, although the free-thyroxine index remains slightly raised. It is likely that these remissions reflect the natural tendency of the disease to remit since propranolol is not considered to have any direct in-vivo effect on thyroid function.
However, because of failure to gain adequate control of symptoms in all patients treated, and the fact that circulating thyroid hormone levels were often not restored to normal, propranolol is considered an unsatisfactory alternative to conventional antithyroid drugs for routine treatment.
PMCID: PMC1589280  PMID: 4122248
9.  Intraluminal force transducer measurements of human oesophageal peristalsis 
Gut  1972;13(6):464-470.
A force transducer has been developed to measure peristaltic propulsive force (`pull') in the oesophagus. Utilizing a mercury-in-Silastic strain gauge to which a sphere has been attached, this transducer can be calibrated to measure value for force, work, and power. Variability in force values were found between different peristaltic waves at the same site, between different sites in the same subject, and between different control subjects. Control subjects' patterns did not change when the subjects were studied on separate occasions. Patients complaining of dysphagia, who had normal radiographs and manometric tracings, revealed force values that were significantly different from control values. This device should prove useful in the quantitation of oesophageal muscle function.
PMCID: PMC1412207  PMID: 5040833
10.  An assessment of neural network and statistical approaches for prediction of E. coli promoter sites. 
Nucleic Acids Research  1992;20(16):4331-4338.
We have constructed a perceptron type neural network for E. coli promoter prediction and improved its ability to generalize with a new technique for selecting the sequence features shown during training. We have also reconstructed five previous prediction methods and compared the effectiveness of those methods and our neural network. Surprisingly, the simple statistical method of Mulligan et al. performed the best amongst the previous methods. Our neural network was comparable to Mulligan's method when false positives were kept low and better than Mulligan's method when false negatives were kept low. We also showed the correlation between the prediction rates of neural networks achieved by previous researchers and the information content of their data sets.
PMCID: PMC334144  PMID: 1508724

Results 1-10 (10)