Hot and cold contrasts in high resolution Tc-99m planar scintigraphy: a survey of fifty-two camera heads using the PICKER thyroid phantom

This study aimed at comparing the sensitivity and hot and cold contrasts obtained when imaging the Picker thyroid phantom using gamma cameras fitted with either their ultra-high or high-resolution low energy parallel hole collimator. Seventeen camera models from Elscint, General Electric, Siemens and Sopha Medical Vision were involved in the study for a total of 30 cameras and 52 camera heads. A single operator conducted the study in order to minimize the impact of human factors. The phantom contained about 74 MBq 99mTc and was imaged at 10-cm from the collimator face with the energy window recommended by the camera manufacturer. A total of 1 million counts were accumulated. Hot and cold contrasts were in mean about 0.05 higher when using an ultra-high-resolution than when using a high-resolution low energy collimator. This higher contrast was obtained at the expense of a mean reduction in sensitivity of 30%. In particular, Elscint cameras demonstrated a 30% lower sensitivity whatever the collimator type. The Sopha Medical Vision DST and DSX cameras and the General Electric Magicam camera offered the lowest contrasts among the cameras with a high-resolution collimator. Although this was accompanied by a higher than the mean sensitivity for the DST and DSX, the Magicam demonstrated sensitivity roughly identical to the mean of all the cameras with a high-resolution collimator.Peer reviewe

The prevalence of posttraumatic stress disorder in pregnancy and after birth: A systematic review and meta-analysis

BACKGROUND: Previous reviews have provided preliminary insights into risk factors and possible prevalence of Post-traumatic Stress Disorder (PTSD) postpartum with no attempt to examine prenatal PTSD. This study aimed to assess the prevalence of PTSD during pregnancy and after birth, and the course of PTSD over this time. METHODS: PsychINFO, PubMed, Scopus and Web of Science were searched using PTSD terms crossed with perinatal terms. Studies were included if they reported the prevalence of PTSD during pregnancy or after birth using a diagnostic measure. RESULTS: 59 studies (N =24267) met inclusion criteria: 35 studies of prenatal PTSD and 28 studies of postpartum PTSD (where 4 studies provided prevalence of PTSD in pregnancy and postpartum). In community samples the mean prevalence of prenatal PTSD was 3.3% (95%, CI 2.44-4.54). The majority of postpartum studies measured PTSD in relation to childbirth with a mean prevalence of 4.0% (95%, CI 2.77-5.71) in community samples. Women in high-risk groups were at more risk of PTSD with a mean prevalence of 18.95% (95%, CI 10.62-31.43) in pregnancy and 18.5% (95%, CI 10.6-30.38) after birth. Using clinical interviews was associated with lower prevalence rates in pregnancy and higher prevalence rates postpartum. LIMITATIONS: Limitations include use of stringent diagnostic criteria, wide variability of PTSD rates, and inadequacy of studies on prenatal PTSD measured in three trimesters. CONCLUSIONS: PTSD is prevalent during pregnancy and after birth and may increase postpartum if not identified and treated. Assessment and treatment in maternity services is recommended

Distinct Roles of Jasmonates and Aldehydes in Plant-Defense Responses

BACKGROUND: Many inducible plant-defense responses are activated by jasmonates (JAs), C(6)-aldehydes, and their corresponding derivatives, produced by the two main competing branches of the oxylipin pathway, the allene oxide synthase (AOS) and hydroperoxide lyase (HPL) branches, respectively. In addition to competition for substrates, these branch-pathway-derived metabolites have substantial overlap in regulation of gene expression. Past experiments to define the role of C(6)-aldehydes in plant defense responses were biased towards the exogenous application of the synthetic metabolites or the use of genetic manipulation of HPL expression levels in plant genotypes with intact ability to produce the competing AOS-derived metabolites. To uncouple the roles of the C(6)-aldehydes and jasmonates in mediating direct and indirect plant-defense responses, we generated Arabidopsis genotypes lacking either one or both of these metabolites. These genotypes were subsequently challenged with a phloem-feeding insect (aphids: Myzus persicae), an insect herbivore (leafminers: Liriomyza trifolii), and two different necrotrophic fungal pathogens (Botrytis cinerea and Alternaria brassicicola). We also characterized the volatiles emitted by these plants upon aphid infestation or mechanical wounding and identified hexenyl acetate as the predominant compound in these volatile blends. Subsequently, we examined the signaling role of this compound in attracting the parasitoid wasp (Aphidius colemani), a natural enemy of aphids. PRINCIPAL FINDINGS: This study conclusively establishes that jasmonates and C(6)-aldehydes play distinct roles in plant defense responses. The jasmonates are indispensable metabolites in mediating the activation of direct plant-defense responses, whereas the C(6)-aldehyes are not. On the other hand, hexenyl acetate, an acetylated C(6)-aldehyde, is the predominant wound-inducible volatile signal that mediates indirect defense responses by directing tritrophic (plant-herbivore-natural enemy) interactions. SIGNIFICANCE: The data suggest that jasmonates and hexenyl acetate play distinct roles in mediating direct and indirect plant-defense responses. The potential advantage of this "division of labor" is to ensure the most effective defense strategy that minimizes incurred damages at a reduced metabolic cost

Multi-ancestry genome-wide association study of major depression aids locus discovery, fine mapping, gene prioritization and causal inference

Most genome-wide association studies (GWAS) of major depression (MD) have been conducted in samples of European ancestry. Here we report a multi-ancestry GWAS of MD, adding data from 21 cohorts with 88,316 MD cases and 902,757 controls to previously reported data. This analysis used a range of measures to define MD and included samples of African (36% of effective sample size), East Asian (26%) and South Asian (6%) ancestry and Hispanic/Latin American participants (32%). The multi-ancestry GWAS identified 53 significantly associated novel loci. For loci from GWAS in European ancestry samples, fewer than expected were transferable to other ancestry groups. Fine mapping benefited from additional sample diversity. A transcriptome-wide association study identified 205 significantly associated novel genes. These findings suggest that, for MD, increasing ancestral and global diversity in genetic studies may be particularly important to ensure discovery of core genes and inform about transferability of findings

Multi-ancestry genome-wide association study of major depression aids locus discovery, fine mapping, gene prioritization and causal inference.

Most genome-wide association studies (GWAS) of major depression (MD) have been conducted in samples of European ancestry. Here we report a multi-ancestry GWAS of MD, adding data from 21 cohorts with 88,316 MD cases and 902,757 controls to previously reported data. This analysis used a range of measures to define MD and included samples of African (36% of effective sample size), East Asian (26%) and South Asian (6%) ancestry and Hispanic/Latin American participants (32%). The multi-ancestry GWAS identified 53 significantly associated novel loci. For loci from GWAS in European ancestry samples, fewer than expected were transferable to other ancestry groups. Fine mapping benefited from additional sample diversity. A transcriptome-wide association study identified 205 significantly associated novel genes. These findings suggest that, for MD, increasing ancestral and global diversity in genetic studies may be particularly important to ensure discovery of core genes and inform about transferability of findings