Adaptation to nicotine feeding in Myzus persicae.

Lineages of the generalist hemipteran herbivore Myzus persicae (green peach aphid) that have expanded their host range to include tobacco often have elevated nicotine tolerance. The tobacco-adapted M. persicae lineage used in this study was able to reproduce on nicotine-containing artificial diets at concentrations that were 15-fold higher than those that were lethal to a non-adapted M. persicae lineage. Fecundity of the nicotine-tolerant M. persicae lineage was increased by 100 µM nicotine in artificial diet, suggesting that this otherwise toxic alkaloid can serve as a feeding stimulant at low concentrations. This lineage also was pre-adapted to growth on tobacco, exhibiting no drop in fecundity when it was moved onto tobacco from a different host plant. Although growth of the non-tobacco-adapted M. persicae lineage improved after three generations on tobacco, this higher reproductive rate was not associated with increased nicotine tolerance. Myzus persicae gene expression microarrays were used to identify transcripts that are up-regulated in response to nicotine in the tobacco-adapted lineage. Induced expression was found for CYP6CY3, which detoxifies nicotine in M. persicae, other genes encoding known classes of detoxifying enzymes, and genes encoding secreted M. persicae salivary proteins.

Can psychological interventions prevent or reduce risk for perinatal anxiety disorders? A systematic review and meta-analysis.

OBJECTIVE: Little is known about the extent to which interventions can prevent perinatal anxiety disorders. We conducted a systematic review and meta-analysis to examine whether interventions can decrease the onset and symptoms of perinatal anxiety among individuals without an anxiety disorder diagnosis. METHOD: We conducted a comprehensive literature search across five databases related to key concepts: (1) anxiety disorders/anxiety symptom severity (2) perinatal (3) interventions (4) prevention. We included studies that examined a perinatal population without an anxiety disorder diagnosis, included a comparator group, and assessed perinatal anxiety. We included interventions focused on perinatal anxiety as well as interventions to prevent perinatal depression or influence related outcomes (e.g., physical activity). RESULTS: Thirty-six studies were included. No study assessing the incidence of perinatal anxiety disorder (n = 4) found a significant effect of an intervention. Among studies assessing anxiety symptom severity and included in the quantitative analysis (n = 30), a meta-analysis suggested a small standardized mean difference of -0.31 (95% CI [-0.46, -0.16], p < .001) for anxiety at post intervention, favoring the intervention group. Both mindfulness (n = 6), and cognitive behavioral therapy approaches (n = 10) were effective. CONCLUSIONS: Interventions developed for perinatal anxiety were more effective than interventions to prevent perinatal depression. Psychological interventions show promise for reducing perinatal anxiety symptom severity, though interventions specifically targeting anxiety are needed.

Gold-catalysed synthesis of amino acid-derived 2,5-disubstituted oxazoles.

Amino acid-derived propargylic amides are cyclised in a one-pot, Au(III)-catalysed operation to yield 5-bromomethyl oxazoles. These compounds are further elaborated to bis-heterocycles, dipeptide mimics and more.

Microvascular and large vein abnormalities in young patients after mild head trauma and associated fatigue: A brain SPECT evaluation and posture dependence modeling.

OBJECTIVE: MRI and CT scans are usually normal in mild traumatic brain injury (mTBI) although 15-20% of such patients suffer for months from fatigue, headache, anxiety, sleep and other disorders. mTBI is suspected to be a cerebrovascular injury, similar to moderate and severe TBI. Brain SPECT is more sensitive and shows perfusion abnormalities immediately after mTBI. This work explores the perfusion abnormalities for young patients suffering from fatigue several months after mTBI. PATIENTS AND METHODS: Twelve mTBI patients (age:8-36 yr, 4 male) with no history of fatigue prior to trauma were prospectively studied following onset of fatigue 6-12 months after mTBI utilizing 99 m-Tc ECD brain SPECT with early and delayed radiotracer imaging. RESULTS: The perfusion pattern in the mTBI + fatigue group included left hemispheric deficits in frontal lobes (early phase: 15.2 ±â€¯4.2%, delayed phase: 9.9 ±â€¯2.2%) and medial temporal lobes (early phase 11.2 ±â€¯3.7%, delayed phase: 9.0 ±â€¯2.3%). Seven patients additionally showed excess tracer accumulation in the parenchyma surrounding internal jugular bulb inferior to temporal lobe. This was modeled as due to increased cellular permeability from TBI induced oxidative stress affecting endothelial tight junctions and consequent tracer leakage across jugular bulbs. Prolonged posture changes from erect to supine position during imaging increase jugular cross-sectional area and venous wall pressure as has been observed in other disease processes and seem to be responsible for tracer leakage from jugular bulbs in our study. CONCLUSION: This work supports an oxidative stress and BBB disruption model for mTBI. The frontal and temporal lobe perfusion deficits are attributed to anatomical vulnerabilities of these lobes. During a mild TBI both of these lobes are susceptible to grazing impacts with underlying bony ridges. We propose a relation between mTBI and fatigue arising from oxidative stress in mTBI affecting ATP generation and altering endothelial homeostasis for both micro-and-large vasculatures. The tracer leakage observed around jugular veins is due to posture induced changes in venous cross-sections and wall pressure as well as from compromised endothelium post TBI induced oxidative stress.

Subthalamic nuclear tissue contrast in inversion recovery MRI decreases with age in medically refractory Parkinson's disease.

BACKGROUND AND PURPOSE: MRI appearance of subthalamic nucleus (STN) boundaries in Parkinson's patients is often unreliable and not well understood. An objective comparison between FSE T2 and inversion recovery (FSTIR) sequences for stereotactic placement of deep brain stimulators is presented to advance current understanding of STN tissue contrast for refractory Parkinson's disease (PD). METHODS: We imaged 12 PD (age 53-82) and 12 control patients (age 48-77) using T2 and FSTIR sequences at 1.5 T. To avoid MR contrast variation from hardware and patient dependent sources we used an internal thalamic tissue standard to normalize STN signal intensity and correlated it with patient age for these two groups. RESULTS: Normalized FSTIR-weighted STN contrast decreased with increasing age for PD patients (Spearman Rank correlation = -.5) while remained virtually unchanged for controls with age (Spearman Rank coefficient ≈ 0). T2-weighted STN contrast did not show appreciable changes with age for both the groups (Spearman correlation ≈ -.1). CONCLUSIONS: STN, a common stimulation target, shows an age dependent trend for normalized FSTIR MRI contrast. Although larger patient pools are needed, our work points to tissue relaxation-based changes in STN that may provide insight in early stages of brain pathology involving DBS targets in medically refractory Parkinson's disease.

Utilizing fast spin echo MRI to reduce image artifacts and improve implant/tissue interface detection in refractory Parkinson's patients with deep brain stimulators.

Introduction. In medically refractory Parkinson's disease (PD) deep-brain stimulation (DBS) is an effective therapeutic tool. Postimplantation MRI is important in assessing tissue damage and DBS lead placement accuracy. We wanted to identify which MRI sequence can detect DBS leads with smallest artifactual signal void, allowing better tissue/electrode edge conspicuity. Methods. Using an IRB approved protocol 8 advanced PD patients were imaged within MR conditional safety guidelines at low RF power (SAR ≤ 0.1 W/kg) in coronal plane at 1.5T by various sequences. The image slices were subjectively evaluated for diagnostic quality and the lead contact diameters were compared to identify a sequence least affected by metallic leads. Results and Discussion. Spin echo and fast spin echo based low SAR sequences provided acceptable image quality with comparable image blooming (enlargement) of stimulator leads. The mean lead diameters were 2.2 ± 0.1 mm for 2D, 2.1 ± 0.1 mm for 3D, and 4.0 ± 0.2 mm for 3D MPRAGE sequence. Conclusion. Low RF power spin echo and fast spin echo based 2D and 3D FSE sequences provide acceptable image quality adjacent to DBS leads. The smallest artifactual blooming of stimulator leads is present on 3D FSE while the largest signal void appears in the 3D MPRAGE sequence.

Neural bases of food perception: coordinate-based meta-analyses of neuroimaging studies in multiple modalities.

OBJECTIVE: The purpose of this study was to compare the results of the three food-cue paradigms most commonly used for functional neuroimaging studies to determine: i) commonalities and differences in the neural response patterns by paradigm and ii) the relative robustness and reliability of responses to each paradigm. METHODS: Functional magnetic resonance imaging studies using standardized stereotactic coordinates to report brain responses to food cues were identified using online databases. Studies were grouped by food-cue modality as: i) tastes (8 studies); ii) odors (8 studies); and, iii) images (11 studies). Activation likelihood estimation was used to identify statistically reliable regional responses within each stimulation paradigm. RESULTS: Brain response distributions were distinctly different for the three stimulation modalities, corresponding to known differences in location of the respective primary and associative cortices. Visual stimulation induced the most robust and extensive responses. The left anterior insula was the only brain region reliably responding to all three stimulus categories. CONCLUSIONS: These findings suggest visual food-cue paradigm as promising candidate for imaging studies addressing the neural substrate of therapeutic interventions.

Effect of low refocusing angle in T1-weighted spin echo and fast spin echo MRI on low-contrast detectability: a comparative phantom study at 1.5 and 3 Tesla.

MRI tissue contrast is not well preserved at high field. In this work, we used a phantom with known, intrinsic contrast (3.6%) for model tissue pairs to test the effects of low angle refocusing pulses and magnetization transfer from adjacent slices on intrinsic contrast at 1.5 and 3 Tesla. Only T1-weighted spin echo sequences were tested since for such sequences the contrast loss, tissue heating, and image quality degradation at high fields seem to present significant diagnostic and quality issues. We hypothesized that the sources of contrast loss could be attributed to low refocusing angles that do not fulfill the Hahn spin echo conditions or to magnetization transfer effects from adjacent slices in multislice imaging. At 1.5 T the measured contrast was 3.6% for 180° refocusing pulses and 2% for 120° pulses, while at 3 T, it was 4% for 180° and only 1% for 120° refocusing pulses. There was no significant difference between single slice and multislice imaging suggesting little or no role played by magnetization transfer in the phantom chosen. Hence, one may conclude that low angle refocusing pulses not fulfilling the Hahn spin echo conditions are primarily responsible for significant deterioration of T1-weighted spin echo image contrast in high-field MRI.