Urban outbreak of a Brucella melitensis infection in an Argentine family: Clinical and diagnostic aspects

Abstract An outbreak of Brucella melitensis in a family was studied. From the fourteen family members who ate unpasteurized goat cheese nine became ill. Patients included four females and five males of 8 to 75 years old. In seven of the patients the diagnosis was confirmed by positive blood culture for B. melitensis biovar 1. All the patients were analyzed by standard tube agglutination (STA) and standard tube agglutination with 2-mercaptoethanol (STA-2ME) tests at the time of diagnosis. In six of the patients, ELISA assays were used to assess the humoral immune anti-protein and anti-lipopolysaccharide (LPS) responses. Anti-LPS IgG antibodies were detected in all of the patients. Anti-proteins IgG antibodies were present at significant levels in all the studied patients including the STA-2ME negative ones.     

Swapping of the N-terminus of VDAC1 with VDAC3 restores full activity of the channel and confers anti-aging features to the cell

Voltage-dependent anion-selective channels (VDACs) are pore-forming proteins allowing the permeability of the mitochondrial outer membrane. The VDAC3 isoform is the least abundant and least active in a complementation assay performed in a yeast strain devoid of porin-1. We swapped the VDAC3 N-terminal 20 amino acids with homologous sequences from the other isoforms. The substitution of the VDAC3 N-terminus with the VDAC1 N-terminus caused the chimaera to become more active than VDAC1. The VDAC2 N-terminus improved VDAC3 activity, though to a lesser extent. The VDAC3 carrying the VDAC1 N-terminus was able to complement the lack of the yeast porin in mitochondrial respiration and in modulation of reactive oxygen species (ROS). This chimaera increased life span, indicating a more efficient bioenergetic metabolism and/or a better protection from ROS.     

Structure-Based Statistical Mechanical Model Accounts for the Causality and Energetics of Allosteric Communication

Allostery is one of the pervasive mechanisms through which proteins in living systems carry out enzymatic activity, cell signaling, and metabolism control. Effective modeling of the protein function regulation requires a synthesis of the thermodynamic and structural views of allostery. We present here a structure-based statistical mechanical model of allostery, allowing one to observe causality of communication between regulatory and functional sites, and to estimate per residue free energy changes. Based on the consideration of ligand free and ligand bound systems in the context of a harmonic model, corresponding sets of characteristic normal modes are obtained and used as inputs for an allosteric potential. This potential quantifies the mean work exerted on a residue due to the local motion of its neighbors. Subsequently, in a statistical mechanical framework the entropic contribution to allosteric free energy of a residue is directly calculated from the comparison of conformational ensembles in the ligand free and ligand bound systems. As a result, this method provides a systematic approach for analyzing the energetics of allosteric communication based on a single structure. The feasibility of the approach was tested on a variety of allosteric proteins, heterogeneous in terms of size, topology and degree of oligomerization. The allosteric free energy calculations show the diversity of ways and complexity of scenarios existing in the phenomenology of allosteric causality and communication. The presented model is a step forward in developing the computational techniques aimed at detecting allosteric sites and obtaining the discriminative power between agonistic and antagonistic effectors, which are among the major goals in allosteric drug design.     

Static and free-vibration analyses of dental prosthesis and atherosclerotic human artery by refined finite element models

Static and modal responses of representative biomechanical structures are investigated in this paper by employing higher-order theories of structures and finite element approximations. Refined models are implemented in the domain of the Carrera unified formulation (CUF), according to which low- to high-order kinematics can be postulated as arbitrary and, eventually, hierarchical expansions of the generalized displacement unknowns. By using CUF along with the principle of virtual work, the governing equations are expressed in terms of fundamental nuclei of finite element arrays. The fundamental nuclei are invariant of the theory approximation order and can be opportunely employed to implement variable kinematics theories of bio-structures. In this work, static and free-vibration analyses of an atherosclerotic plaque of a human artery and a dental prosthesis are discussed. The results from the proposed methodologies highlight a number of advantages of CUF models with respect to already established theories and commercial software tools. Namely, (i) CUF models can represent correctly the higher-order phenomena related to complex stress/strain field distributions and coupled mode shapes; (ii) bio-structures can be modeled in a component-wise sense by only employing the physical boundaries of the problem domain and without making any geometrical simplification. This latter aspect, in particular, can be currently accomplished only by using three-dimensional analysis, which may be computationally unbearable as complex bio-systems are considered.     

Epidemiological survey of Trichinella infection in domestic, synanthropic and sylvatic animals from Argentina

The presence of Trichinella larvae was investigated in 247 samples taken from domestic, synanthropic and sylvatic animals, collected during 1996 to 2005 in 12 endemic provinces of Trichinella infection in Argentina. Muscle larvae of Trichinella from 65 infected animals were identified at the species level by single larva nested polymerase chain reaction (PCR) technique based on the variability within the expansion segment V (ESV) region of the ribosomal DNA. Trichinella infections were found in 97 of 164 pigs, 38 of 56 pork products, two domestic dogs, one domestic cat, 7 of 11 armadillos and 3 of 9 synanthropic rats. All Trichinella isolates were identified as Trichinella spiralis by nested PCR. These findings add new data on the epidemiology of trichinellosis and should be considered when implementing new strategies to control this zoonosis.     

Pathways and intermediates of amyloid fibril formation

The lack of understanding of amyloid fibril formation at the molecular level is a major obstacle in devising strategies to interfere with the pathologies linked to peptide or protein aggregation. In particular, little is known on the role of intermediates and fibril elongation pathways as well as their dependence on the intrinsic tendency of a polypeptide chain to self-assembly by β-sheet formation (β-aggregation propensity). Here, coarse-grained simulations of an amphipathic polypeptide show that a decrease in the β-aggregation propensity results in a larger heterogeneity of elongation pathways, despite the essentially identical structure of the final fibril. Protofibrillar intermediates that are thinner, shorter and less structured than the final fibril accumulate along some of these pathways. Moreover, the templated formation of an additional protofilament on the lateral surface of a protofibril is sometimes observed as a collective transition. Conversely, for a polypeptide model with a high β-aggregation propensity, elongation proceeds without protofibrillar intermediates. Therefore, changes in intrinsic β-aggregation propensity modulate the relative accessibility of parallel routes of aggregation.     

Echinococcus granulosus: DNA extraction from germinal layers allows strain determination in fertile and nonfertile hydatid cysts

A method for the isolation of Echinococcus granulosus DNA from germinal layers of hydatid cysts is described. The method includes a hexadecyltrimethylammonium bromide/chloroform extraction and an adsorption to diatomaceous earth suspension. DNA suitable for polymerase chain reaction was obtained and used for parasite strain determination by mitochondrial cytochrome c oxidase I gene sequencing. Fertile and nonfertile cyst isolates from sheep, cattle, pigs, and humans were characterized. Hitherto, no direct parasite strain characterization has been made on nonfertile hydatid cysts, whereas here we report that nonfertile hydatid cysts were produced by sheep strain (G1 genotype) in sheep, cattle, and humans and by pig strain (G7 genotype) in pigs.     

A Prediction Model Based on Biomarkers and Clinical Characteristics for Detection of Lung Cancer in Pulmonary Nodules

Lung cancer early detection by low-dose computed tomography (LDCT) can reduce the mortality. However, LDCT increases the number of indeterminate pulmonary nodules (PNs), whereas 95% of the PNs are ultimately false positives. Modalities for specifically distinguishing between malignant and benign PNs are urgently needed. We previously identified a panel of peripheral blood mononucleated cell (PBMC)-miRNA (miRs-19b-3p and -29b-3p) biomarkers for lung cancer. This study aimed to evaluate efficacy of integrating biomarkers and clinical and radiological characteristics of smokers for differentiating malignant from benign PNs. We analyzed expression of 2 miRNAs (miRs-19b-3p and -29b-3p) in PBMCs of a training set of 137 individuals with PNs. We used multivariate logistic regression analysis to develop a prediction model based on the biomarkers, radiographic features of PNs, and clinical characteristics of smokers for identifying malignant PNs. The performance of the prediction model was validated in a testing set of 111 subjects with PNs. A prediction model comprising the two biomarkers, spiculation of PNs and smoking pack-year, was developed that had 0.91 area under the curve of the receiver operating characteristic for distinguishing malignant from benign PNs. The prediction model yielded higher sensitivity (80.3% vs 72.6%) and specificity (89.4% vs 81.9%) compared with the biomarkers used alone (all P < .05). The performance of the prediction model for malignant PNs was confirmed in the validation set. We have for the first time demonstrated that the integration of biomarkers and clinical and radiological characteristics could efficiently identify lung cancer among indeterminate PNs.