Bactericidal Activity Does Not Predict Sterilizing Activity: The Case of Rifapentine in the Murine Model of Mycobacterium ulcerans Disease

Background

Since 2004, treatment of Mycobacterium ulcerans disease, or Buruli ulcer, has shifted from surgery to daily treatment with streptomycin (STR) + rifampin (RIF) for 8 weeks. For shortening treatment duration, we tested the potential of daily rifapentine (RPT), a long-acting rifamycin derivative, as a substitute for RIF.

Methodology/Principal Findings

BALB/c mice were infected with M. ulcerans in the right hind footpad and treated either daily (7/7) with STR+RIF or five days/week (5/7) with STR+RIF or STR+RPT for 4 weeks, beginning 28 days after infection when CFU counts were 4.88±0.51.The relative efficacy of the drug treatments was compared by footpad CFU counts during treatment and median time to footpad swelling after treatment cessation as measure of sterilizing activity. All drug treatments were bactericidal. After 1 week of treatment, the decline in CFU counts was significantly greater in treated mice but not different between the three treated groups. After 2 weeks of treatment, the decline in CFU was greater in mice treated with STR+RPT 5/7 than in mice treated with STR+RIF 7/7 and STR+RIF 5/7. After 3 and 4 weeks of treatment, CFU counts were nil in mice treated with STR+RPT and reduced by more than 3 and 4 logs in mice treated with STR+RIF 5/7 and STR+RIF 7/7, respectively. In sharp contrast to the bactericidal activity, the sterilizing activity was not different between all drug regimens although it was in proportion to the treatment duration.

Conclusions/Significance

The better bactericidal activity of daily STR+RIF and especially of STR+RPT did not translate into better prevention of relapse, possibly because relapse-freecure after treatment of Buruli ulcer is more related to the reversal of mycolactone-induced local immunodeficiency by drug treatment rather than to the bactericidal potency of drugs.     

Decellularized Cartilage May Be a Chondroinductive Material for Osteochondral Tissue Engineering

Extracellular matrix (ECM)-based materials are attractive for regenerative medicine in their ability to potentially aid in stem cell recruitment, infiltration, and differentiation without added biological factors. In musculoskeletal tissue engineering, demineralized bone matrix is widely used, but recently cartilage matrix has been attracting attention as a potentially chondroinductive material. The aim of this study was thus to establish a chemical decellularization method for use with articular cartilage to quantify removal of cells and analyze the cartilage biochemical content at various stages during the decellularization process, which included a physically devitalization step. To study the cellular response to the cartilage matrix, rat bone marrow-derived mesenchymal stem cells (rBMSCs) were cultured in cell pellets containing cells only (control), chondrogenic differentiation medium (TGF-β), chemically decellularized cartilage particles (DCC), or physically devitalized cartilage particles (DVC). The chemical decellularization process removed the vast majority of DNA and about half of the glycosaminoglycans (GAG) within the matrix, but had no significant effect on the amount of hydroxyproline. Most notably, the DCC group significantly outperformed TGF-β in chondroinduction of rBMSCs, with collagen II gene expression an order of magnitude or more higher. While DVC did not exhibit a chondrogenic response to the extent that DCC did, DVC had a greater down regulation of collagen I, collagen X and Runx2. A new protocol has been introduced for cartilage devitalization and decellularization in the current study, with evidence of chondroinductivity. Such bioactivity along with providing the ‘raw material’ building blocks of regenerating cartilage may suggest a promising role for DCC in biomaterials that rely on recruiting endogenous cell recruitment and differentiation for cartilage regeneration.     

Proteomic profile of culture filtrate from the Brazilian vaccine strain <Emphasis Type="Italic">Mycobacterium bovis</Emphasis> BCG Moreau compared to <Emphasis Type="Italic">M. bovis</Emphasis> BCG Pasteur

Background  

Bacille Calmette-Guerin (BCG) is currently the only available vaccine against tuberculosis (TB) and comprises a heterogeneous family of sub-strains with genotypic and phenotypic differences. The World Health Organization (WHO) affirms that the characterization of BCG sub-strains, both on genomic and proteomic levels, is crucial for a better comprehension of the vaccine. In addition, these studies can contribute in the development of a more efficient vaccine against TB. Here, we combine two-dimensional electrophoresis (2DE) and mass spectrometry to analyse the proteomic profile of culture filtrate proteins (CFPs) from M. bovis BCG Moreau, the Brazilian vaccine strain, comparing it to that of BCG Pasteur. CFPs are considered of great importance given their dominant immunogenicity and role in pathogenesis, being available for interaction with host cells since early infection.     

PROPERTIES OF ACID β-d-GALACTOSIDASE ISOLATED FROM I-CELL DISEASE BRAIN AND SPLEEN

Abstract— Acid 4-methylumbelliferyl β- d -galactosidase activity from autopsied I-cell disease brain and spleen tissues was 28% and 35% respectively of normal activity. Acid β- d -gatactosidase (β- d -galactoside galactohydrolase, EC 3.2.1.23) from two I-cell disease brains demonstrated a 5-fold increase over normal for the proportion of enzyme activity which did not adsorb to Concanavalin A-Sepharose 4B, while acid β- d -galactosidase from two I-cell disease spleens demonstrated a 21–35-fold increase in the proportion of unadsorbed enzyme activity. Normal and I-cell disease acid β- d -galactosidase present in crude brain and spleen supernatant fluids and in preparations partially purified on Concanavalin A-Sepharose 4B had similar apparent K _m values with respect to 4-methylumbelliferyl β- d -galactopyranoside and G_M1-ganglioside. Isoelectric focusing profiles of normal and I-cell disease acid β- d -galactosidase from crude brain and spleen-supernatant fluids and partially purified preparations were similar. Neuraminidase treatment and subsequent isoelectric focusing of the partially purified normal and I-cell disease enzyme preparations from brain and spleen revealed increases in the proportion of I-cell β- d -galactosidases found at neutral pH values, suggesting that the electrophoretic variations observed for the I-cell enzymes may not be attributed solely to changes in sialic acid composition.     

Molecular models of NS3 protease variants of the Hepatitis C virus

Background  

Hepatitis C virus (HCV) currently infects approximately three percent of the world population. In view of the lack of vaccines against HCV, there is an urgent need for an efficient treatment of the disease by an effective antiviral drug. Rational drug design has not been the primary way for discovering major therapeutics. Nevertheless, there are reports of success in the development of inhibitor using a structure-based approach. One of the possible targets for drug development against HCV is the NS3 protease variants. Based on the three-dimensional structure of these variants we expect to identify new NS3 protease inhibitors. In order to speed up the modeling process all NS3 protease variant models were generated in a Beowulf cluster. The potential of the structural bioinformatics for development of new antiviral drugs is discussed.     

The mitogenome of Onchocerca volvulus from the Brazilian Amazonia focus

We report here the first complete mitochondria genome of Onchocerca volvulus from a focus outside of Africa. An O. volvulus mitogenome from the Brazilian Amazonia focus was obtained using a combination of high-throughput and Sanger sequencing technologies. Comparisons made between this mitochondrial genome and publicly available mitochondrial sequences identified 46 variant nucleotide positions and suggested that our Brazilian mitogenome is more closely related to Cameroon-origin mitochondria than West African-origin mitochondria. As well as providing insights into the origins of Latin American onchocerciasis, the Brazilian Amazonia focus mitogenome may also have value as an epidemiological resource.     

Altered cellular infiltration and cytokine levels during early <Emphasis Type="Italic">Mycobacterium tuberculosis</Emphasis><Emphasis Type="Italic">sigC</Emphasis> mutant infection are associated with late-stage disease attenuation and milder immunopathology in mice

Background  

Mouse virulence assessments of certain Mycobacterium tuberculosis mutants have revealed an immunopathology defect in which high tissue CFU counts are observed but the tissue pathology and lethality are reduced. M. tuberculosis mutants which grow and persist in the mouse lungs, but have attenuated disease progression, have the immunopathology (imp) phenotype. The antigenic properties of these strains may alter the progression of disease due to a reduction in host immune cell recruitment to the lungs resulting in disease attenuation and prolonged host survival.     

Linking demographic and food‐web models to understand management trade‐offs

Alternatives in ecosystem‐based management often differ with respect to trade‐offs between ecosystem values. Ecosystem or food‐web models and demographic models are typically employed to evaluate alternatives, but the approaches are rarely integrated to uncover conflicts between values. We applied multistate models to a capture–recapture dataset on common guillemots Uria aalge breeding in the Baltic Sea to identify factors influencing survival. The estimated relationships were employed together with Ecopath‐with‐Ecosim food‐web model simulations to project guillemot survival under six future scenarios incorporating climate change. The scenarios were based on management alternatives for eutrophication and cod fisheries, issues considered top priority for regional management, but without known direct effects on the guillemot population. Our demographic models identified prey quantity (abundance and biomass of sprat Sprattus sprattus) as the main factor influencing guillemot survival. Most scenarios resulted in projections of increased survival, in the near (2016–2040) and distant (2060–2085) future. However, in the scenario of reduced nutrient input and precautionary cod fishing, guillemot survival was projected to be lower in both future periods due to lower sprat stocks. Matrix population models suggested a substantial decline of the guillemot population in the near future, 24% per 10 years, and a smaller reduction, 1.1% per 10 years, in the distant future. To date, many stakeholders and Baltic Sea governments have supported reduced nutrient input and precautionary cod fishing and implementation is underway. Negative effects on nonfocal species have previously not been uncovered, but our results show that the scenario is likely to negatively impact the guillemot population. Linking model results allowed identifying trade‐offs associated with management alternatives. This information is critical to thorough evaluation by decision‐makers, but not easily obtained by food‐web models or demographic models in isolation. Appropriate datasets are often available, making it feasible to apply a linked approach for better‐informed decisions in ecosystem‐based management.