STAT3 inhibition with Galiellalactone effectively targets the prostate cancer stem-like cell population."

Cancer stem cells (CSCs) are a small subpopulation of quiescent cells with the potential to differentiate into tumor cells. CSCs are involved in tumor initiation and progression and contribute to treatment failure through their intrinsic resistance to chemo- or radiotherapy, thus representing a substantial concern for cancer treatment. Prostate CSCs’ activity has been shown to be regulated by the transcription factor Signal Transducer and Activator of Transcription 3 (STAT3). Here we investigated the effect of galiellalactone (GL), a direct STAT3 inhibitor, on CSCs derived from prostate cancer patients, on docetaxel-resistant spheres with stem cell characteristics, on CSCs obtained from the DU145 cell line in vitro and on DU145 tumors in vivo. We found that GL significantly reduced the viability of docetaxel-resistant and patient-derived spheres. Moreover, CSCs isolated from DU145 cells were sensitive to low concentrations of GL, and the treatment with GL suppressed their viability and their ability to form colonies and spheres. STAT3 inhibition down regulated transcriptional targets of STAT3 in these cells, indicating STAT3 activity in CSCs. Our results indicate that GL can target the prostate stem cell niche in patient-derived cells, in docetaxel-resistant spheres and in an in vitro model. We conclude that GL represents a promising therapeutic approach for prostate cancer patients, as it reduces the viability of prostate cancer-therapy-resistant cells in both CSCs and non-CSC populations

The use of polyvinyl alcohol glutaraldehyde as solid-phase in ELISA for plague

Discs of polyvinyl alcohol cross-linked with glutaraldehyde were synthesized under acid catalysis (H2SO4). Then, the antigen F1 purified from Yersinia pestis was covalently linked to this modified polymer. Afterwards, an enzyme-linked immunosorbent assay (ELISA) was established for the diagnosis of plague in rabbit and human. The best conditions for the method were achieved by using 1.3 ¼g of F1 prepared in 0.067 M phosphate buffer, pH 7.2, containing 1 M NaCl (PBS); anti-IgG peroxidase conjugate diluted 6,000 times and as a blocking agent 3% w/v skim milk in PBS. The titration of positive rabbit serum according to this procedure detected antibody concentrations up to 1:12,800 times. The present method, the conventional ELISA and passive haemagglutination assay are compared

Large screening of CA-MRSA among <it>Staphylococcus aureus </it>colonizing healthy young children living in two areas (urban and rural) of Portugal

<p>Abstract</p> <p>Background</p> <p>The incidence of pediatric infections due to community-associated methicillin-resistant <it>Staphylococcus aureus </it>(CA-MRSA), including children with no identifiable risk factors, has increased worldwide in the last decade. This suggests that healthy children may constitute a reservoir of MRSA in the community. In this study, nested within a larger one on nasopharyngeal ecology, we aimed to: (i) evaluate the prevalence of MRSA colonizing young children in Portugal; and (ii) compare results with those obtained in a study conducted a decade ago, when this prevalence was <0.5%.</p> <p>Methods</p> <p>In the years 2006, 2007, and 2009, nasopharyngeal samples were obtained from 2,100 children aged up to 6 years attending day-care centers. <it>S. aureus </it>were isolated by routine procedures and strains were tested for susceptibility against a panel of 12 antimicrobial agents. MRSA isolates were further characterized by SmaI-PFGE profiling, MLST, <it>spa </it>typing, SCC<it>mec </it>typing, and presence of virulence factors.</p> <p>Results</p> <p>Seventeen percent of the children carried <it>S. aureus</it>. Among the 365 isolates, non-susceptibility rates were 88% to penicillin, 14% to erythromycin, 6% to clindamycin, 2% to tetracycline, and <1% to oxacillin, rifampicin, ciprofloxacin, and SXT. Three MRSA strains were isolated. These had properties of CA-MRSA, such as low-level resistance to oxacillin and limited resistance to non-beta-lactams. Two CA-MRSA were related to USA700 (ST72-IV): one was ST72-IVc, <it>spa </it>type t148; the other was ST939-IVa (ST939 is a single locus variant (SLV) of ST72), <it>spa </it>type t324. The third strain was related to USA300 (ST8-IV) being characterized by ST931 (SLV of ST8)-VI, <it>spa </it>type t008. The three MRSA strains were PVL-negative, but all carried LukE-LukD leukocidin, hemolysins gamma, gamma variant and beta, and staphylococcal enterotoxin <it>sel</it>.</p> <p>Conclusions</p> <p>Our results, based on analysis of <it>S. aureus </it>isolated from nasopharyngeal samples, suggest that in Portugal the prevalence of CA-MRSA carriage in healthy young children remains extremely low favoring the exclusion of this group as a reservoir of such isolates.</p

A Streptococcus pneumoniae infection model in larvae of the wax moth Galleria mellonella

The bacterium Streptococcus pneumoniae is a leading human opportunistic pathogen. The limitations of the current vaccine have led to increased recognition of the need to understand bacterial behaviour and competitive dynamics using in vivo models of infection. Here, we investigate the potential application of the larvae of the wax moth Galleria mellonella as an informative infection model. Larvae were challenged with a range of doses of S. pneumoniae isolates differing in known virulence factors to determine the LD(50) values. Infection dynamics were determined by obtaining bacterial counts from larvae over a time course. Differences in virulence between serotypes could be distinguished in this host. Infection with strains differing in known virulence factors demonstrated predicted differences in virulence. Acapsulate and pneumolysin-negative strains were less virulent than their respective wild types. A large reduction in virulence was seen in strains lacking cell wall D-alanylation. The mortality of G. mellonella larvae is attributable to bacterial growth within larvae, while surviving larvae are able to clear infections by reducing bacterial numbers. These data demonstrate that G. mellonella larvae represent an in vivo infection model with applications for investigating aspects of bacterial-host interactions such as the role of antimicrobial peptide activity and resistance