Ultra-low-dose non-contrast CT and CT angiography can be used interchangeably for assessing maximal abdominal aortic diameter

BACKGROUND: Routine CT scans may increasingly be used to document normal aortic size and to detect incidental abdominal aortic aneurysms. PURPOSE: To determine whether ultra-low-dose non-contrast CT (ULDNC-CT) can be used instead of the gold standard CT angiography (CTA) for assessment of maximal abdominal aortic diameter. MATERIALS AND METHODS: This retrospective study included 50 patients who underwent CTA and a normal-dose non–contrast CT for suspected renal artery stenosis. ULDNC-CT datasets were generated from the normal-dose non–contrast CT datasets using a simulation technique. Using the centerline technique, radiology consultants (n = 4) and residents (n = 3) determined maximal abdominal aortic diameter. The limits of agreement with the mean (LOAM) was used to access observer agreement. LOAM represents how much a measurement by a single observer may plausibly deviate from the mean of all observers on the specific subject. RESULTS: Observers completed 1400 measurements encompassing repeated CTA and ULDNC-CT measurements. The mean diameter was 24.0 and 25.0 mm for CTA and ULDNC-CT, respectively, yielding a significant but minor mean difference of 1.0 mm. The 95% LOAM reproducibility was similar for CTA and ULDNC-CT (2.3 vs 2.3 mm). In addition, the 95% LOAM and mean diameters were similar for CTA and ULDNC-CT when observers were grouped as consultants and residents. CONCLUSIONS: Ultra-low-dose non–contrast CT exhibited similar accuracy and reproducibility of measurements compared with CTA for assessing maximal abdominal aortic diameter supporting that ULDNC-CT can be used interchangeably with CTA in the lower range of aortic sizes

Structural imaging findings are related to clinical complications in chronic pancreatitis

Background/objectives: Structural pancreatic changes and complications related to chronic pancreatitis are well described, but little is known about their relationship. We aimed to explore the associations between pancreatic morphology and clinical complications in a large chronic pancreatitis cohort. Methods: The Scandinavian Baltic Pancreatic Club database collects registrations on patients with definite or probable chronic pancreatitis according to the M-ANNHEIM diagnostic criteria. In this cross-sectional study, we used multivariate logistic regression analyses to evaluate whether imaging-based structural pancreatic changes were associated with common clinical complications. We adjusted for sex, age, disease duration, current alcohol abuse and current smoking. Results: We included 742 patients with a mean age of 55 years. Among these, 68% were males, 69% had pancreatic exocrine insufficiency, 35% had diabetes, 12% were underweighted and 68% reported abdominal pain. Main pancreatic duct obstruction, severe (i.e. more than 14) calcifications, pancreatic atrophy and parenchymal changes throughout the entire pancreas (continuous organ involvement) were positively associated with pancreatic exocrine insufficiency. Continuous organ involvement and pseudocysts were positively and negatively associated with diabetes, respectively. Pancreatic atrophy and severe calcifications were positively associated with underweight, and severe calcifications were negatively associated with pain. Conclusions: This study shows independent associations between distinct structural changes on pancreatic imaging and clinical complications in chronic pancreatitis. Pancreatic atrophy, severe calcifications and continuous organ involvement may be of particular clinical relevance, and these findings should motivate monitoring of pancreatic function and nutritional status.publishedVersio

Ammonium-Acetate Is Sensed by Gustatory and Olfactory Neurons in Caenorhabditis elegans

Background: Caenorhabditis elegans chemosensation has been successfully studied using behavioral assays that treat detection of volatile and water soluble chemicals as separate senses, analogous to smell and taste. However, considerable ambiguity has been associated with the attractive properties of the compound ammonium-acetate (NH 4Ac). NH 4Ac has been used in behavioral assays both as a chemosensory neutral compound and as an attractant. Methodology/Main Findings: Here we show that over a range of concentrations NH4Ac can be detected both as a water soluble attractant and as an odorant, and that ammonia and acetic acid individually act as olfactory attractants. We use genetic analysis to show that NaCl and NH4Ac sensation are mediated by separate pathways and that ammonium sensation depends on the cyclic nucleotide gated ion channel TAX-2/TAX-4, but acetate sensation does not. Furthermore we show that sodium-acetate (NaAc) and ammonium-chloride (NH4Cl) are not detected as Na + and Cl 2 specific stimuli, respectively. Conclusions/Significance: These findings clarify the behavioral response of C. elegans to NH4Ac. The results should have an impact on the design and interpretation of chemosensory experiments studying detection and adaptation to soluble compounds in the nematode Caenorhabditis elegans

Natural polymorphisms in C. elegans HECW-1 E3 ligase affect pathogen avoidance behaviour

available in PMC 2012 June 22.Heritable variation in behavioural traits generally has a complex genetic basis1, and thus naturally occurring polymorphisms that influence behaviour have been defined in only rare instances2,3. The isolation of wild strains of Caenorhabditis elegans has facilitated the study of natural genetic variation in this species4 and provided insights into its diverse microbial ecology5. C. elegans responds to bacterial infection with conserved innate immune responses6-8 and, while lacking the immunological memory of vertebrate adaptive immunity, exhibits an aversive learning response to pathogenic bacteria9. Here, we report the molecular characterization of naturally occurring coding polymorphisms in a C. elegans gene encoding a conserved HECT domain-containing E3 ubiquitin ligase, HECW-1. We show that two distinct polymorphisms in neighbouring residues of HECW-1 each affect C. elegans behavioural avoidance of a lawn of Pseudomonas aeruginosa. Neuronspecific rescue and ablation experiments, and genetic interaction analysis suggest that HECW-1 functions in a pair of sensory neurons to inhibit P. aeruginosa lawn avoidance behaviour through inhibition of the neuropeptide receptor NPR-110, which we have previously shown promotes P. aeruginosa lawn avoidance behaviour11. Our data establish a molecular basis for natural variation in a C. elegans behaviour that may undergo adaptive changes in response to microbial pathogens.National Institutes of Health (U.S.) (NIH Grant GM084477