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Near-surface geophysical techniques are useful for the characterization of archaeological areas because of their ability to rapidly cover wide extensions and obtain high-resolution data to identify the location for archaeological excavations. However, in hyperarid environments usual geophysical techniques may fail to obtain the expected results due to the dry near surface. This study proposes an integration of ground penetrating radar (GPR) and electromagnetic induction (EMI) techniques, to elucidate the origin of thousands of aligned circular features located at the Iluga archaeological area emplaced on one of the driest places on Earth (Pampa del Tamarugal, Atacama Desert). The GPR was useful to recognize alluvial deposits, sandy aeolian filling in pre-existing holes and roots right underneath circular features. Magnetic susceptibility data derived from the EMI in-phase component, usually considered a complementary result, were useful to identify fireplaces in the vicinity of the alignments. These geophysical findings were verified with an archaeological excavation. It has been found that circular features resulted from an extensive deforestation process in the Pampa del Tamarugal, consisting in the extraction of both trunk and roots of algarrobos (Prosopis chilensis) or tamarugos (Prosopis tamarugo), likely for recent charcoal production. The proposed methodology delivers promising results for archaeological and shallow geological studies in hyperarid and dry environments. [ABSTRACT FROM AUTHOR]

This article examines the social implications of pottery circulation in the southern Andes during the Late pre-Hispanic periods (ca. A.D. 1000–1550). In particular, its goal is to understand the role of Yavi-Chicha pottery in the dynamics of interaction between two regions: the Chicha valleys in the border of Bolivia and Argentina and the Atacama in Chile. We do so through exploring the life history of Yavi-Chicha pottery: where and how it was manufactured, how it circulated, and the possible consumers, building on new ceramic analysis combined with previous results and discussed in relation to available research. Based on mineralogical and chemical data, we argue that Yavi-Chicha vessels that circulated in Chile, mostly polished jars, were manufactured somewhere in the Talina Valley, in Bolivia, ruling out the possibility that this pottery was produced in the Atacama. This indicates social interaction between the Chicha Region and the Atacama. In the context of a consistent relationship between the two regions, the circulation of Yavi-Chicha vessels could have involved a variety of practices, agents and motivations as two main types of traffic (embedded and specialized) seemed to have coexisted in the routes that connect both regions. This leads us to consider different possible scenarios of Yavi-Chicha ceramic consumption, implying different processes of negotiation and interaction between both regions. These vessels would have circulated as inalienable possessions (or identity markers), as trade items or as politically charged gifts under Inca State auspices (as gifts and political marker). Overall, we suggest that the presence of Yavi-Chicha ceramics in the Atacama would have been the result of an effort to maintain and consolidate preexisting interregional social relations between the Chicha Region and the Atacama. [ABSTRACT FROM AUTHOR]

The diphtheria toxin translocation (T) domain inserts into the endosomal membrane in response to the endosomal acidification and enables the delivery of the catalytic domain into the cell. The insertion pathway consists of a series of conformational changes that occur in solution and in the membrane and leads to the conversion of a water-soluble state into a transmembrane state. In this work, we utilize various biophysical techniques to characterize the insertion pathway from the thermodynamic perspective. Thermal and chemical unfolding measured by differential scanning calorimetry, circular dichroism, and tryptophan fluorescence reveal that the free energy of unfolding of the T-domain at neutral and mildly acidic pH differ by 3-5 kcal/mol, depending on the experimental conditions. Fluorescence correlation spectroscopy measurements show that the free energy change from the membrane-competent state to the interfacial state is approximately −8 kcal/mol and is pH-independent, while that from the membrane-competent state to the transmembrane state ranges between −9.5 and −12 kcal/mol, depending on the membrane lipid composition and pH. Finally, the thermodynamics of transmembrane insertion of individual helices was tested using an in vitro assay that measures the translocon-assisted integration of test sequences into the microsomal membrane. These experiments suggest that even the most hydrophobic helix TH8 has only a small favorable free energy of insertion. The free energy for the insertion of the consensus insertion unit TH8-TH9 is slightly more favorable, yet less favorable than that measured for the entire protein, suggesting a cooperative effect for the membrane insertion of the helices of the T-domain. [ABSTRACT FROM AUTHOR]

Diphtheria toxin translocation (T) domain inserts in lipid bilayers upon acidification of the environment. Computational and experimental studies have suggested that low pH triggers a conformational change of the T-domain in solution preceding membrane binding. The refolded membrane-competent state was modeled to be compact and mostly retain globular structure. In the present work, we investigate how this refolded state interacts with membrane interfaces in the early steps of T-domain's membrane association. Coarse-grained molecular dynamics simulations suggest two distinct membrane-bound conformations of the T-domain in the presence of bilayers composed of a mixture of zwitteronic and anionic phospholipids (POPC:POPG with a 1:3 molar ratio). Both membrane-bound conformations show a common near parallel orientation of hydrophobic helices TH8-TH9 relative to the membrane plane. The most frequently observed membrane-bound conformation is stabilized by electrostatic interactions between the N-terminal segment of the protein and the membrane interface. The second membrane-bound conformation is stabilized by hydrophobic interactions between protein residues and lipid acyl chains, which facilitate deeper protein insertion in the membrane interface. A theoretical estimate of a free energy of binding of a membrane-competent T-domain to the membrane is provided. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Lupus nephritis (LN) is one of the most serious complications of systemic lupus erythematosus (SLE) since it is the major predictor of poor prognosis. The purpose of this study was to examine the clinical and immunological characteristics associated with LN development during the course of SLE in Colombians. Therefore, patients with SLE followed at five different referral centers in Medellin, Bogota, and Cali were included in this cross-sectional and multicenter study. Factors influencing LN were assessed by conditional logistic regression analysis, adjusting by gender, age at onset, duration of disease, and city of origin. The entire sample population included 467 patients, of whom 51% presented with LN. The presence of anti-dsDNA antibodies (adjusted odds ratio (AOR), 2.06; 95% confidence interval (CI), 1.16-3.65), pleuritis (AOR, 3.82; 95% CI, 1.38-10.54), and hypertension (AOR, 2.63; 95% CI, 1.23-5.62) were positively associated with LN, whereas the presence of anti-La antibodies was a protective factor against LN development (AOR, 0.4; 95% CI, 0.19-0.85). A review of literature on LN in different populations is made. The identified clinical- and laboratory-associated factors would assist earlier diagnosis and guide decisions on therapeutic interventions on this critical and frequent complication of SLE. [ABSTRACT FROM AUTHOR]