Test-retest variability of high resolution positron emission tomography (PET) imaging of cortical serotonin (5HT2A) receptors in older, healthy adults

<p>Abstract</p> <p>Background</p> <p>Position emission tomography (PET) imaging using [¹⁸F]-setoperone to quantify cortical 5-HT_2Areceptors has the potential to inform pharmacological treatments for geriatric depression and dementia. Prior reports indicate a significant normal aging effect on serotonin 5HT_2Areceptor (5HT_2AR) binding potential. The purpose of this study was to assess the test-retest variability of [¹⁸F]-setoperone PET with a high resolution scanner (HRRT) for measuring 5HT_2AR availability in subjects greater than 60 years old. Methods: Six healthy subjects (age range = 65–78 years) completed two [¹⁸F]-setoperone PET scans on two separate occasions 5–16 weeks apart.</p> <p>Results</p> <p>The average difference in the binding potential (BP_ND) as measured on the two occasions in the frontal and temporal cortical regions ranged between 2 and 12%, with the lowest intraclass correlation coefficient in anterior cingulate regions.</p> <p>Conclusion</p> <p>We conclude that the test-retest variability of [¹⁸F]-setoperone PET in elderly subjects is comparable to that of [¹⁸F]-setoperone and other 5HT_2AR radiotracers in younger subject samples.</p

Past changes in the vertical distribution of ozone - Part 3: Analysis and interpretation of trends

This is the final version of the article. It first appeared from Copernicus Publications via http://dx.doi.org/10.5194/acp-15-9965-2015Abstract. Trends in the vertical distribution of ozone are reported and compared for a number of new and recently revised data sets. The amount of ozone-depleting compounds in the stratosphere (as measured by equivalent effective stratospheric chlorine – EESC) was maximised in the second half of the 1990s. We examine the periods before and after the peak to see if any change in trend is discernible in the ozone record that might be attributable to a change in the EESC trend, though no attribution is attempted. Prior to 1998, trends in the upper stratosphere (~ 45 km, 4 hPa) are found to be −5 to −10 % per decade at mid-latitudes and closer to −5 % per decade in the tropics. No trends are found in the mid-stratosphere (28 km, 30 hPa). Negative trends are seen in the lower stratosphere at mid-latitudes in both hemispheres and in the deep tropics. However, it is hard to be categorical about the trends in the lower stratosphere for three reasons: (i) there are fewer measurements, (ii) the data quality is poorer, and (iii) the measurements in the 1990s are perturbed by aerosols from the Mt Pinatubo eruption in 1991. These findings are similar to those reported previously even though the measurements for the main satellite and ground-based records have been revised. There is no sign of a continued negative trend in the upper stratosphere since 1998: instead there is a hint of an average positive trend of ~ 2 % per decade in mid-latitudes and ~ 3 % per decade in the tropics. The significance of these upward trends is investigated using different assumptions of the independence of the trend estimates found from different data sets. The averaged upward trends are significant if the trends derived from various data sets are assumed to be independent (as in Pawson et al., 2014) but are generally not significant if the trends are not independent. This occurs because many of the underlying measurement records are used in more than one merged data set. At this point it is not possible to say which assumption is best. Including an estimate of the drift of the overall ozone observing system decreases the significance of the trends. The significance will become clearer as (i) more years are added to the observational record, (ii) further improvements are made to the historic ozone record (e.g. through algorithm development), and (iii) the data merging techniques are refined, particularly through a more rigorous treatment of uncertainties. The support of SPARC, IO3C, IGACO-O3 and NDACC was essential to the success of the initiative. Neil Harris thanks the UK Natural Environment Research Council for an Advanced Research Fellowship. Work at the Jet Propulsion Laboratory was performed under contract with the National Aeronautics and Space Administration. Measurements at Lauder are core funded through New Zealand’s Ministry of Business, Innovation and Employment, while those at Woolongong are supported by the Australian Research Council

Modifications des lipoprotéines de basse densité (LDL) par radiolyse γ de l'eau : reconnaissance par les récepteurs APO B/E et «scavenger», et cytotoxicité vis-à-vis de fibroblastes humains en culture

Le but de ce travail était d'étudier la reconnaissance par le récepteur B/E de fibroblastes humains et le récepteur "scavenger" de macrophages, de LDL d'origine humaine oxydées par radiolyse γ de l'eau (O2°-/OH°). Leur cytotoxicité vis-à-vis de fibroblastes humains en culture a également été testée. Nous avons montré que les LDL oxydées (doses comprises entre 600 et 1800 Gy) étaient encore partiellement reconnues par le récepteur apo B/E des fibroblastes MRC5. Ces LDL oxydées étaient cytotoxiques vis-à-vis de fibroblastes humains en culture et cet effet était dépendant de la dose d'irradiation. En revanche, la reconnaissance par le récepteur "scavenger" des macrophages ne semblait pas dépendante de la dose d'irradiation, dans nos conditions expérimentales. La peroxydation des LDL par les radicaux générés par radiolyse γ de l'eau semblerait se distinguer de celle induite par le cuivre et pourrait constituer un modèle expérimental intéressant pour l'introduction de lipides peroxydés dans le milieu intracellulaire