Spatial extent of an outbreak in animal epidemics

Characterizing the spatial extent of epidemics at the outbreak stage is key to controlling the evolution of the disease. At the outbreak, the number of infected individuals is typically small, and therefore, fluctuations around their average are important: then, it is commonly assumed that the susceptible–infected–recovered mechanism can be described by a stochastic birth–death process of Galton–Watson type. The displacements of the infected individuals can be modeled by resorting to Brownian motion, which is applicable when long-range movements and complex network interactions can be safely neglected, like in the case of animal epidemics. In this context, the spatial extent of an epidemic can be assessed by computing the convex hull enclosing the infected individuals at a given time. We derive the exact evolution equations for the mean perimeter and the mean area of the convex hull, and we compare them with Monte Carlo simulations.     

Generation of an atlas of the proximal femur and its application to trabecular bone analysis

Automatic placement of anatomically corresponding volumes of interest and comparison of parameters against a standard of reference are essential components in studies of trabecular bone. Only recently, in vivo MR images of the proximal femur, an important fracture site, could be acquired with high‐spatial resolution. The purpose of this MRI trabecular bone study was two‐fold: (1) to generate an atlas of the proximal femur to automatically place anatomically corresponding volumes of interest in a population study and (2) to demonstrate how mean models of geodesic topological analysis parameters can be generated to be used as potential standard of reference. Ten females were used to generate the atlas and geodesic topological analysis models, and 10 females were used to demonstrate the atlas‐based trabecular bone analysis. All alignments were based on three‐dimensional (3D) multiresolution affine transformations followed by 3D multiresolution free‐form deformations. Mean distances less than 1 mm between aligned femora, and sharp edges in the atlas and in fused gray‐level images of registered femora indicated that the anatomical variability was well accommodated and explained by the free‐form deformations. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

In silico modeling of interstitial lung mechanics: implications for disease development and repair

In this perspective, we first review some of the published literature on structural modeling of the mechanical properties of the lung parenchyma. Based on a recent study, we demonstrate why mechanical dysfunction accompanying parenchymal diseases such as pulmonary fibrosis and emphysema can follow a very different course from the progression of the underlying microscopic pathophysiology itself, particularly in the early stages. The key idea is related to the concept of percolation on elastic networks where the bulk modulus of the network suddenly changes when the fibrotic stiff regions or the emphysematous holes become suddenly connected across the network. We also introduce the concept of depercolation as a basis for the rational optimization of tissue repair. Specifically, we use these network models to predict the functional improvements that a hypothetical biological or tissue engineering repair could achieve. We find that rational targeted repair can have significant benefits over generic random repair. This concept may find application in the treatment of lung fibrosis, surgical, bronchoscopic, or biological lung volume reduction, or any future alveolar regeneration or tissue engineering solution to the repair of connective tissue damage of the lung.     

Correlation between Human Placental Lactogen Levels and Glucose Metabolism in Pregnant Women with Intrauterine Growth Retardation

Twenty pregnant women with fetal growth retardation and 20 pregnant women with appropriate for gestational age fetuses (controls) were recruited after the 28th week of gestation. Samples were collected for estimation of serum insulin and human placental lactogen (HPL) levels in the fasting state and a glucose tolerance test was carried out on all the subjects. The results showed the glucose and HPL levels to be significantly lower in the fetal growth retardation group compared to controls. There were no differences in the fasting serum insulin levels in the 2 groups. Fetal growth retardation appears to be linked with the absence of development of the physiological 'diabetogenic' state in the second half of pregnancy. This maternal hypoglycaemic state is associated with low HPL levels and not with raised maternal insulin levels as measured in the fasting state.     

Clinicohistological disparity in leprosy

A healthy elderly man presented with localized isolated erythematous tender, anesthetic, oval plaque with little scaling near the medial angle of right eye, of 3 years' duration without any obvious nerve thickening, treated irregularly with WHO MDT for 3 months, clinically simulating BT leprosy with downgrading reversal reaction. Histology showed a BL granuloma with plenty of solid staining AFB within the foamy macrophages. Lepromin test was very weakly positive. The case is discussed in the light of clinicohistological disparity in leprosy cases with review of relevant literatures. A stress is laid on the importance of newer MDT in such cases to prevent drug-resistance, relapse and recurrence.     

In vitro activity of ertapenem against common clinical isolates in relation to human pharmacokinetics

The in vitro activity of ertapenem against bacterial pathogens isolated from patients with moderate to severe complicated intra-abdominal, complicated skin/skin structure, acute pelvic, or complicated urinary tract infection or community acquired pneumonia was compared to ceftriaxone and piperacillin-tazobactam and related to known plasma concentrations of the three agents. Ertapenem was more potent against methicillin-susceptible Staphylococcus aureus (MSSA) than ceftriaxone and piperacillin-tazobactam and was more potent and more active than both of these agents against Enterobacteriaceae and anaerobes. Piperacillin-tazobactam was the most active agent against enterococci and Pseudomonas aeruginosa. All isolates of Enterobacteriaceae (n=1088), Streptococcus pyogenes (n=37), Streptococcus agalactiae (n=48), MSSA (n=187), Haemophilus influenzae (n=59), and Moraxella catarrhalis (n=9) were susceptible to ertapenem; < 1% of 1284 anaerobes and only 1 of 113 Streptococcus pneumoniae (a penicillin-resistant isolate) were resistant to ertapenem. The MIC value at which 90% of all Enterobacteriaceae, streptococci, MSSA, H. influenzae, M. catarrhalis, and anaerobes were inhibited (MIC90) was < or = 1 microg/ml and below the mean plasma concentration of total ertapenem following a 1 g intravenous infusion for at least 24 hours, i.e., the entire recommended dosing interval, and below the free drug concentration for at least 8 h.