Sensitivity of Soil Restoration Indicators during Páramo Succession in the High Tropical Andes: Chronosequence and Permanent Plot Approaches

The aim of this study was to analyze indicators of soil restoration during secondary succession in a heterogeneous valley in the high tropical Andes. A combination of chronosequence and permanent plot methods was used to detect changes in this heterogeneous matrix. Thirty-six plots with different fallow times (1–9 years) and four noncultivated plots with natural vegetation (páramo) were sampled twice in a 3-year interval (1996 and 1999). The following soil properties were determined: total C and N, pH, exchangeable bases, cation exchange capacity, and microbial biomass N (MB-N). Using the chronosequence approach, successional increases in soil pH and Mg were detected, pointing to these variables as indicators of soil restoration during the fallow period. Comparing the noncultivated páramo with the fallow plots, a significant decrease in MB-N was found, suggesting that this is a sensitive agricultural disturbance indicator. The permanent plot analysis failed to detect successional trends in any of the study variables, probably as a result of a lack of sensitivity of the indicators used within the 3-year interval. Nevertheless, a strong acidification was detected by the permanent plot method when fallow plots were cultivated. We conclude that the size of important soil components such as total soil organic matter or microbial biomass is not a sensitive soil restoration indicator in these heterogeneous mountain systems but that other integrative variables such as pH could be more sensitive to successional changes in key soil processes (e.g., nitrification or nutrient losses).     

Leptospiral TlyC is an extracellular matrix-binding protein and does not present hemolysin activity

The role of TlyA, TlyB and TlyC proteins in the biology of Leptospira is still uncertain. Although these proteins have been considered as putative hemolysins, we demonstrate that leptospiral recombinant TlyB and TlyC do not possess hemolytic activity. However, further experiments showed that TlyC is a surface-exposed protein that seems to bind to laminin, collagen IV and fibronectin. The expression of both proteins was detected both in vitro and in vivo. Our findings suggest that TlyB and TlyC are not directly involved in hemolysis, and that TlyC may contribute to Leptospira binding to extracellular matrix (ECM) during host infection.     

The Ras guanine nucleotide exchange factor RasGRF1 promotes matrix metalloproteinase-3 production in rheumatoid arthritis synovial tissue

Introduction  

Fibroblast-like synoviocytes (FLS) from rheumatoid arthritis (RA) patients share many similarities with transformed cancer cells, including spontaneous production of matrix metalloproteinases (MMPs). Altered or chronic activation of proto-oncogenic Ras family GTPases is thought to contribute to inflammation and joint destruction in RA, and abrogation of Ras family signaling is therapeutic in animal models of RA. Recently, expression and post-translational modification of Ras guanine nucleotide releasing factor 1 (RasGRF1) was found to contribute to spontaneous MMP production in melanoma cancer cells. Here, we examine the potential relationship between RasGRF1 expression and MMP production in RA, reactive arthritis, and inflammatory osteoarthritis synovial tissue and FLS.     

Comparative proteomic analysis of whole saliva from chronic periodontitis patients

Chronic periodontal disease is a chronic inflammatory process affecting tooth supporting tissues in the presence of pathogenic bacterial biofilm. There is some evidence for changes in the protein composition of whole saliva from chronic periodontitis patients, but there have been no studies using a proteomic approach. Hence, the aim of this study was to compare the protein profiles of unstimulated whole saliva from patients with periodontitis and healthy subjects by two complementary approaches (2D-gel electrophoresis and liquid chromatography). Protein spots of interest were analyzed by MALDI-TOF-TOF, and the data was complemented by an ESI-Q-TOF experiment. The analyses revealed that subjects with periodontal disease have increased amounts of blood proteins (serum albumin and hemoglobin) and immunoglobulin, and they have a lower abundance of cystatin compared to the control group. A higher number of protein spots were observed in the periodontitis group, of which most were identified as alpha-amylase. This higher number of alpha-amylase variants seems to be caused by hydrolysis by cysteine proteases under such inflammatory conditions. This approach gives novel insights into alterations of salivary protein in presence of periodontal inflammation and may contribute to the improvement of periodontal diagnosis.     

Co-existence of Radiative and Non-Radiative Surface Plasmon Resonance Modes: Power Balance and Influence of Film Morphology

Plasmonics - The power balance and conditions of co-existing radiative and non-radiative surface plasmon resonance modes have been exploited at the metal film-water interface. Angular (AIM) and...     

In house reverse membrane hybridisation assay versus GenoType MTBDRplus and their performance to detect mutations in the genes rpoB,katG and inhA

Drug-resistant tuberculosis (TB) threatens global TB control and is a major public health concern in several countries. We therefore developed a multiplex assay (LINE-TB/MDR) that is able to identify the most frequent mutations related to rifampicin (RMP) and isoniazid (INH) resistance. The assay is based on multiplex polymerase chain reaction, membrane hybridisation and colorimetric detection targeting of rpoB and katG genes, as well as the inhA promoter, which are all known to carry specific mutations associated with multidrug-resistant TB (MDR-TB). The assay was validated on a reference panel of 108 M. tuberculosis isolates that were characterised by the proportion method and by DNA sequencing of the targets. When comparing the performance of LINE-TB/MDR with DNA sequencing, the sensitivity, specificity and agreement were 100%, 100% and 100%, respectively, for RMP and 77.6%, 90.6% and 88.9%, respectively, for INH. Using drug sensibility testing as a reference standard, the performance of LINE-TB/MDR regarding sensitivity, specificity and agreement was 100%, 100% and 100% (95%), respectively, for RMP and 77%, 100% and 88.7% (82.2-95.1), respectively, for INH. LINE-TB/MDR was compared with GenoType MTBDRplus for 65 isolates, resulting in an agreement of 93.6% (86.7-97.5) for RIF and 87.4% (84.3-96.2) for INH. LINE-TB/MDR warrants further clinical validation and may be an affordable alternative for MDR-TB diagnosis.