Biotyping of enterotoxigenic Staphylococcus aureus by enterotoxin gene cluster (egc) polymorphism and spa typing analyses

Thirty-five Staphylococcus aureus strains, including 10 reference strains and 25 strains recovered from clinical specimens and food samples, were analyzed by PCR REA (restriction endonucleases analysis) of the egc operon and spa typing. Nineteen spa types and seven different egc operons, including four putative new egc variants, were revealed. In 13 strains, allelic variants of sei and/or seg were found. By an analysis of their nucleotide sequence identities, a new homogeneous cluster of a sei variant, called the sei variant, was detected in six strains. In addition, the prototype sei was shown to be more polymorphic than assumed so far. Seven strains possessed the recently described seg variant, also exhibiting several nucleotide exchanges. spa typing was more effective than REA egc grouping as a typing technique. Since, in some cases, the REA typing method was able to discriminate strains showing the same spa type, it must be considered for PCR approaches involved in diagnostic procedures and may be useful for epidemiological studies. Hence, the polyphasic approach used in this study can be reliably and advantageously applied for typing egc-positive S. aureus strains.     

Treatment of genotype 1b HCV-related chronic hepatitis: efficacy and toxicity of three different interferon alfa-2b/ribavirin combined regimens in naive patients

This prospective open-label randomized trial of chronic hepatitis C genotype-1b patients compared compared the efficacy and safety of peg-interferon alfa-2b administered once-weekly versus interferon alfa-2b thrice-weekly or daily, both in combination with ribavirin. Seventy-eight previously untreated patients, with biopsy-documented genotype 1 chronic HCV and persistently elevated ALT levels and detectable HCV RNA, were randomized (26 subjects each) to receive: interferon alfa-2b at 6MIUs.c./three-times-weekly (group A) or interferon alfa-2b, 3MIUs.c./daily (group B) or peg-interferon alfa-2b 1.5mcg/Kg s.c./once-weekly (group C). All regimens included standard weight-based doses of ribavirin (800, 1,000 or 1,200 mg/day) administered for 52-weeks. Patients in the three groups were comparable for age, sex, viral load, ALT value and histological-activity-index (HAI). Therapy was completed by 22, 20 and 23 patients in groups A, B and C, respectively. At the end of treatment, a complete (biochemical and virological) response was observed in 50.0% patients of group A, 57.7% of group B and 65.4% of group C. After an additional 24-weeks of follow-up, a sustained response was observed in 26.9%, 46.1% and 50.0% of patients in groups A, B or C, respectively. Therapy was discontinued by 4, 6 and 2 patients because of adverse events in the above three groups. In naive patients with chronic genotype-lb hepatitis C, a 48 week therapy with peg-interferon or interferon at daily doses combined with ribavirin were both more effective than treatment with thrice-weekly interferon in inducing end of treatment and sustained response. Peg-interferon treatment was better tolerated and provoked significantly fewer therapy discontinuations.     

Antitumoral Efficacy of the Protease Inhibitor Gabexate Mesilate in Colon Cancer Cells Harbouring KRAS, BRAF and PIK3CA Mutations

The employment of anti-epidermal growth factor receptor (EGFR) antibodies represents a backbone of the therapeutic options for the treatment of metastatic colorectal cancer (mCRC). However, this therapy is poorly effective or ineffective in unselected patients. Mutations in KRAS, BRAF and PIK3CA genes have recently emerged as the best predictive factors of low/absent response to EGFR-targeted therapy. Due to the need for efficacious treatment options for mCRC patients bearing these mutations, in this short report we examined the antitumoral activity of the protease inhibitor gabexate mesilate, alone and in combination with the anti-EGFR monoclonal antibody cetuximab, in a panel of human CRC cell lines harbouring a different expression pattern of wild-type/mutated KRAS, BRAF and PIK3CA genes. Results obtained showed that gabexate mesilate significantly inhibited the growth, invasive potential and tumour-induced angiogenesis in all the CRC cells employed in this study (including those ones harbouring dual KRAS/PIK3CA or BRAF/PIK3CA mutation), while cetuximab affected these parameters only in CRC cells with KRAS, BRAF and PIK3CA wild-type. Notably, the antitumoral efficacy of gabexate mesilate and cetuximab in combination was found to be not superior than that observed with gabexate mesilate as single agent. Overall, these preliminary findings suggest that gabexate mesilate could represent a promising therapeutic option for mCRC patients, particularly for those harbouring KRAS, BRAF and PIK3CA mutations, either as mono-therapy or in addition to standard chemotherapy regimens. Further studies to better elucidate gabexate mesilate mechanism of action in CRC cells are therefore warranted.     

Contrasted effects of diversity and immigration on ecological insurance in marine bacterioplankton communities

The ecological insurance hypothesis predicts a positive effect of species richness on ecosystem functioning in a variable environment. This effect stems from temporal and spatial complementarity among species within metacommunities coupled with optimal levels of dispersal. Despite its importance in the context of global change by human activities, empirical evidence for ecological insurance remains scarce and controversial. Here we use natural aquatic bacterial communities to explore some of the predictions of the spatial and temporal aspects of the ecological insurance hypothesis. Addressing ecological insurance with bacterioplankton is of strong relevance given their central role in fundamental ecosystem processes. Our experimental set up consisted of water and bacterioplankton communities from two contrasting coastal lagoons. In order to mimic environmental fluctuations, the bacterioplankton community from one lagoon was successively transferred between tanks containing water from each of the two lagoons. We manipulated initial bacterial diversity for experimental communities and immigration during the experiment. We found that the abundance and production of bacterioplankton communities was higher and more stable (lower temporal variance) for treatments with high initial bacterial diversity. Immigration was only marginally beneficial to bacterial communities, probably because microbial communities operate at different time scales compared to the frequency of perturbation selected in this study, and of their intrinsic high physiologic plasticity. Such local "physiological insurance" may have a strong significance for the maintenance of bacterial abundance and production in the face of environmental perturbations.     

Changes in Cystic Fibrosis Airway Microbial Community Associated with a Severe Decline in Lung Function

Cystic fibrosis (CF) is a genetic disease resulting in chronic polymicrobial infections of the airways and progressive decline in lung function. To gain insight into the underlying causes of severe lung diseases, we aimed at comparing the airway microbiota detected in sputum of CF patients with stable lung function (S) versus those with a substantial decline in lung function (SD). Microbiota composition was investigated by using culture-based and culture-independent methods, and by performing multivariate and statistical analyses. Culture-based methods identified some microbial species associated with a worse lung function, i.e. Pseudomonas aeruginosa, Rothia mucilaginosa, Streptococcus pneumoniae and Candida albicans, but only the presence of S. pneumoniae and R. mucilaginosa was found to be associated with increased severe decline in forced expiratory volume in 1 second (FEV₁). Terminal-Restriction Fragment Length Polymorphism (T-RFLP) analysis revealed a higher bacterial diversity than that detected by culture-based methods. Molecular signatures with a statistically significant odds ratio for SD status were detected, and classified as Pseudomonas, Burkholderia and Shewanella, while for other Terminal Restriction Fragments (T-RFs) no species assignation was achieved. The analysis of T-RFLP data using ecological biodiversity indices showed reduced Evenness in SD patients compared to S ones, suggesting an impaired ecology of the bacterial community in SD patients. Statistically significant differences of the ecological biodiversity indices among the three sub-groups of FEV₁ (normal/mild vs moderate vs severe) were also found, suggesting that the patients with moderate lung disease experienced changes in the airway assembly of taxa. Overall, changes in CF airway microbial community associated with a severe lung function decline were detected, allowing us to define some discriminatory species as well as some discriminatory T-RFs that represent good candidates for the development of predictive biomarkers of substantial decline in lung function.     

Determination of Kaposi's sarcoma-associated herpesvirus C-terminal latency-associated nuclear antigen residues mediating chromosome association and DNA binding

Kaposi's sarcoma-associated herpesvirus latency-associated nuclear antigen (LANA) tethers viral terminal repeat (TR) DNA to mitotic chromosomes to mediate episome persistence. The 1,162-amino-acid LANA protein contains both N- and C-terminal chromosome attachment regions. The LANA C-terminal domain self-associates to specifically bind TR DNA and mitotic chromosomes. Here, we used alanine scanning substitutions spanning residues 1023 to 1145 to investigate LANA self-association, DNA binding, and C-terminal chromosome association. No residues were essential for LANA oligomerization, as assayed by coimmunoprecipitation experiments, consistent with redundant roles for amino acids in self-association. Different subsets of amino acids were important for DNA binding, as assayed by electrophoretic mobility shift assay, and mitotic chromosome association, indicating that distinct C-terminal LANA subdomains effect DNA and chromosome binding. The DNA binding domains of LANA and EBNA1 are predicted to be structurally homologous; certain LANA residues important for DNA binding correspond to those with roles in EBNA1 DNA binding, providing genetic support for at least partial structural homology. In contrast to the essential role of N-terminal LANA chromosome targeting residues in DNA replication, deficient C-terminal chromosome association did not reduce LANA-mediated DNA replication.     

The interleukin-8 (IL-8/CXCL8) receptor inhibitor reparixin improves neurological deficits and reduces long-term inflammation in permanent and transient cerebral ischemia in rats

Leukocyte infiltration is viewed as a pharmacological target in cerebral ischemia. We previously reported that reparixin, a CXCL8 receptor blocker that inhibits neutrophil infiltration, and related molecules can reduce infarct size in a rat model of transient middle cerebral artery occlusion (MCAO). The study aims were to compare the effects of reparixin in transient and permanent MCAO using varied treatment schedules and therapeutic windows to evaluate effects on long-term neurological deficits and late inflammatory response. Reparixin, administered for 1 to 3 days, 3.5 to 6 h after MCAO, ameliorates neurological function recovery and inhibits long-term inflammation. The infarct size reduction at 24 h, evaluated by TTC staining, is more pronounced in transient MCAO. MRI analysis identified a decrease in the progression of infarct size by reparixin that was more evident at 48 h in permanent MCAO, and was associated with a significantly improved recovery from long-term neurological deficits.     

Species accumulation over space and time in European Plio-Holocene mammals

The rate of increase in species number with sampled area is one issue of major interest in ecology. Species number increases with sampled time as well, though this kind of analysis is much rarer in literature. Species-area and species-time relationships have been recently integrated in a single model, which allows studying how time and area interact with each other in determining the cumulative increase in species richness. Here we studied species-area, species-time, and species-time-area relationships in Plio-Holocene large mammals of Western Eurasia, by using an extensive database including 184 species distributed in 685 fossil sites. We found that the increase of species number with time is much higher than with area. When sampling inequality of fossil localities in time and space is accounted for, time and area interact with each other in a negative, though non-linear fashion. The intense climatic changes that characterized the Plio-Holocene period apparently affected both species-area and species-time relationships in large mammals, by increasing the slope of the former during the Pliocene and middle Pleistocene, and of the latter during younger, climatically harsher, late Pleistocene times. This study emphasizes the importance of accounting for time and space in tracing paleodiversity curves.