No abstract

Tuberculosis (TB) is an infectious disease that still causes more than 1.5 million deaths annually. The World Health Organization estimates that around 30% of the world's population is latently infected. However, the mechanisms responsible for 10% of this reserve (i.e., of the latently infected population) developing an active disease are not fully understood, yet. The dynamic hypothesis suggests that endogenous reinfection has an important role in maintaining latent infection. In order to examine this hypothesis for falsifiability, an agentbased model of growth, merging, and proliferation of TB lesions was implemented in a computational bronchial tree, built with an iterative algorithm for the generation of bronchial bifurcations and tubes applied inside a virtual 3D pulmonary surface. The computational model was fed and parameterized with computed tomography (CT) experimental data from 5 latently infected minipigs. First, we used CT images to reconstruct the virtual pulmonary surfaces where bronchial trees are built. Then, CT data about TB lesion' size and location to each minipig were used in the parameterization process. The model's outcome provides spatial and size distributions of TB lesions that successfully reproduced experimental data, thus reinforcing the role of the bronchial tree as the spatial structure triggering endogenous reinfection. A sensitivity analysis of the model shows that the final number of lesions is strongly related with the endogenous reinfection frequency and maximum growth rate of the lesions, while their mean diameter mainly depends on the spatial spreading of new lesions and the maximum radius. Finally, the model was used as an in silico experimental platform to explore the transition from latent infection to active disease, identifying two main triggering factors: a high inflammatory response and the combination of a moderate inflammatory response with a small breathing amplitude.

Radiographic features of 71 patients (48 men, 23 women) with nosocomial Legionella pneumophila pneumonia were assessed and compared with those of other nosocomial series of L pneumophila pneumonia. Sixteen patients were assessed retrospectively and 55 prospectively. Chest radiographs were assessed at the onset of the illness, 10 days later, and at 3 months. Erythromycin was given to 67 patients at the time of the diagnosis and to the remaining four at a later stage. Forty eight patients were over the age of 60. On the initial chest radiograph 53 of the 71 patients had unilateral shadowing (23 of them in the right lung); 35 had unilobar shadowing and the remaining 36 had more than one affected lobe. Pleural effusion was present in 24 cases and cavitation in 2. One patient had evidence of a pericardial effusion. At 10 days 21 patients had evidence of radiographic progression (14 ipsilateral), but 28 had improved. At 3 months 36 patients had an abnormal radiograph, 30 showing residual scarring, 15 loss of volume, six pleural shadows and two cavitation. Our series shows a lesser incidence of unilateral shadowing and pleural effusion than other nosocomial series and a lesser tendency to progression, but more patients had radiographic abnormalities at long term follow up.

A right subclavian artery pseudoaneurysm caused by blunt trauma is described. CT and digital subtraction angiography helped us to establish a correct diagnosis. Radiologic features of subclavian artery aneurysms and relevant literature are briefly discussed.

Our primary objective was to assess the independent association between liver fibrosis (LF) and abdominal fat accumulation (AFA) and fatty liver disease (FLD). We also aimed to determine the diagnostic accuracy of AFA and FLD for the prediction of cirrhosis measured using unenhanced low-dose computed tomography (CT). This is a cross-sectional study in stable human immunodeficiency virus (HIV)/hepatitis C virus (HCV)-coinfected patients with active HCV replication. CT was used to quantify fat content in segments III and VI of the liver and AFA. Transient elastometry was used to stage LF. Multivariate logistic regression, receiver operating characteristic curve analysis, and linear mixed model analysis were applied. One hundred fifteen HIV/HCVcoinfected patients were included. Cirrhosis was detected in 20.8% (24 patients). There was a high correlation between anthropometric characteristics and radiological variables. The factors independently associated with cirrhosis were albumin concentration [odds ratio (OR), 0.69; 95% confidence interval (CI), 0.58-0.83; p < .0001] and visceral fat accumulation (OR, 1.02; 95% CI, 1.01-1.04; p = .0003). Multinomial analysis showed that visceral fat area (VFA) was the factor independently associated with stage F2 (OR, 1.02; 95% CI, 1.0-1.03; p < .005) and albumin concentration with stage F3 (OR, 0.75; 95% CI, 0.64-0.89; p < .001). VFA was the only radiological variable with an area under the curve >0.7 for the prediction of cirrhosis. There was no inter-or intraobserver variability in the measurement of AFA; however, high interobserver variability was recorded in the measurement of FLD. The association of VFA with cirrhosis, the high reproducibility of CT for the measurement of VFA, and the ability of VFA to predict cirrhosis make CT a suitable technique for identifying HIV/HCV-coinfected patients for closer surveillance.