Multicenter evaluation of the fully automated Bactec MGIT 960 system for susceptibility testing of Mycobacterium tuberculosis to pyrazinamide: comparison with the radiometric Bactec 460TB system

One hundred and fifty clinical isolates of Mycobacterium tuberculosis were tested for susceptibility to pyrazinamide using the fully automated Bactec MGIT 960 system and the radiometric Bactec 460TB system. The overall concordance rate between MGIT 960 and radiometric system was 100% and the mean turnaround times to report the susceptibility test results were almost identical (6.37 and 6.8 days, respectively).     

Irradiation effect on the structure of bacterial communities associated with the oriental fruit fly,Bactrocera dorsalis

The role of symbiotic microbes in insects, especially the beneficial character of this interaction for insects, has received much attention in recent years as it has been related to important aspects of the host insects' biology such as development, reproduction, survival, and fitness. Among insect hosts, tephritid fruit flies are well known to form beneficial associations with their symbionts. To control these destructive agricultural pests, environmentally friendly approaches, like the sterile insect technique as a component of integrated pest management strategies, remain most effective. In this study, changes in the bacterial profile of mass‐reared oriental fruit flies, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), were examined in both larval and adult stages and also after irradiation by employing a 16S rRNA gene‐based Illumina sequencing approach. Proteobacteria was the prevalent bacterial phylum in non‐irradiated adults and larvae. Alphaproteobacteria was the most abundant class in larvae but almost absent in adults, which was dominated by Gammaproteobacteria. Firmicutes were present in both developmental stages but at lower relative abundance. At genus level, Acetobacter prevailed in the larval stage and members of the Enterobacteriaceae family in adults. Irradiated samples exhibited higher diversity and richness indices compared to the non‐irradiated oriental fruit flies, whereas no significant changes were observed between the two developmental stages of the non‐irradiated samples. Lactobacillus, members of the Orbacecae family, and Morganella were detected but to a lesser degree upon irradiation, whereas the relative abundance of Lactococcus and Orbus increased. The bacterial profile of larvae appeared to be different compared to that of adult B. dorsalis flies. The subsequent application of irradiation at the pupal stage led to the development of different microbiota between treated and untreated samples, affecting diversity and operational taxonomic unit composition. Irradiated samples of oriental fruit flies were characterized by higher species diversity and richness.     

The apoplastic antioxidant system and altered cell wall dynamics influence mesophyll conductance and the rate of photosynthesis

Mesophyll conductance (g_m), the diffusion of CO₂ from substomatal cavities to the carboxylation sites in the chloroplasts, is a highly complex trait driving photosynthesis (net CO₂ assimilation, A_N). However, little is known concerning the mechanisms by which it is dynamically regulated. The apoplast is considered as a ‘key information bridge’ between the environment and cells. Interestingly, most of the environmental constraints affecting g_m also cause apoplastic responses, cell wall (CW) alterations and metabolic rearrangements. Since CW thickness is a key determinant of g_m, we hypothesize that other changes in this cellular compartiment should also influence g_m. We study the relationship between the antioxidant apoplastic system and CW metabolism and the g_m responses in tobacco plants (Nicotiana sylvestris L.) under two abiotic stresses (drought and salinity), combining in vivo gas‐exchange measurements with analyses of antioxidant activities, CW composition and primary metabolism. Stress treatments imposed substantial reductions in A_N (58–54%) and g_m (59%), accompanied by a strong antioxidant enzymatic response at the apoplastic and symplastic levels. Interestingly, apoplastic but not symplastic peroxidases were positively related to g_m. Leaf anatomy remained mostly stable; however, the stress treatments significantly affected the CW composition, specifically pectins, which showed significant relationships with A_N and g_m. The treatments additionally promoted a differential primary metabolic response, and specific CW‐related metabolites including galactose, glucosamine and hydroxycinnamate showed exclusive relationships with g_m independent of the stress. These results suggest that g_m responses can be attributed to specific changes in the apoplastic antioxidant system and CW metabolism, opening up more possibilities for improving photosynthesis using breeding/biotechnological strategies.     

Automated diagnosis of brain tumours astrocytomas using probabilistic neural network clustering and support vector machines

A computer-aided diagnosis system was developed for assisting brain astrocytomas malignancy grading. Microscopy images from 140 astrocytic biopsies were digitized and cell nuclei were automatically segmented using a Probabilistic Neural Network pixel-based clustering algorithm. A decision tree classification scheme was constructed to discriminate low, intermediate and high-grade tumours by analyzing nuclear features extracted from segmented nuclei with a Support Vector Machine classifier. Nuclei were segmented with an average accuracy of 86.5%. Low, intermediate, and high-grade tumours were identified with 95%, 88.3%, and 91% accuracies respectively. The proposed algorithm could be used as a second opinion tool for the histopathologists.     

Primary effusion lymphoma. A case report

BACKGROUND: Primary effusion lymphoma (PEL) is a rare type of lymphoma that presents as an effusion, seldom with evidence of a solid neoplasm elsewhere; thus, cytology is the basic diagnostic method. It usually occurs in HIV-positive males with a history of Kaposi's sarcoma (KS), and DNA sequences of human herpesvirus 8 (HHV-8) are detected by molecular analysis. The distinct morphologic, immunophenotypic, molecular and clinical characteristics render this neoplasm a new pathologic entity. CASE: A 57-year-old, HIV-positive man presented to the hospital with ascites and absence of neoplasm on radiologic investigation. Cytologic evaluation of the ascitic fluid revealed the presence of highly atypical, pleomorphic lymphoid cells. Immunocytochemistry of the lymphoma cells was positive for CD45 (leukocyte common antigen), CD30 and epithelial membrane antigen antigens and negative for panB, panT and cytokeratin antigens. DNA sequences of HHV-8 were identified by polymerase chain reaction (PCR), and DNA ploidy analysis showed aneuploidy. The patient died 5 months after the diagnosis. CONCLUSION: Conventional and ThinPrep (Cytyc Corp., Boxborough, Massachusetts, U.S.A.) cytology, in combination with immunocytochemistry and PCR for HHV-8 DNA sequences, can lead to an accurate diagnosis of PEL. DNA ploidy analysis confirms the aggressive nature of this neoplasm.     

Novel GES/IBC extended-spectrum beta-lactamase variants with carbapenemase activity in clinical enterobacteria

Two clinical isolates, an Escherichia coli and a Klebsiella pneumoniae, with decreased susceptibility to carbapenems were studied. This phenotype was associated with production of novel GES/IBC variant beta-lactamases, designated GES-3 (from E. coli) and GES-4 (from K. pneumoniae), exhibiting carbapenemase activity. Both enzymes possessed Ser at Ambler's position 170 instead of Gly found in the beta-lactamases GES-1 and IBC-1 that lack carbapenemase activity. Additionally, position 104 in GES-4 was occupied by a Lys as in IBC-1. bla(GES-3) and bla(GES-4) occurred as gene cassettes in the variable regions of class 1 integrons carried by plasmids. The structure of the GES-4-encoding integron was similar to that of previously described IBC-1 integrons. The GES-3-encoding integron was, most likely, truncated at the 3' conserved segment.     

Flower preferences and pollen transport networks for cavity‐nesting solitary bees: Implications for the design of agri‐environment schemes

Floral foraging resources are valuable for pollinator conservation on farmland, and their provision is encouraged by agri‐environment schemes in many countries. Across Europe, wildflower seed mixtures are widely sown on farmland to encourage pollinators, but the extent to which key pollinator groups such as solitary bees exploit and benefit from these resources is unclear. We used high‐throughput sequencing of 164 pollen samples extracted from the brood cells of six common cavity‐nesting solitary bee species (Osmia bicornis, Osmia caerulescens, Megachile versicolor, Megachile ligniseca, Megachile centuncularis and Hylaeus confusus) which are widely distributed across the UK and Europe. We documented their pollen use across 19 farms in southern England, UK, revealing their forage plants and examining the structure of their pollen transport networks. Of the 32 plant species included currently in sown wildflower mixes, 15 were recorded as present within close foraging range of the bees on the study farms, but only Ranunculus acris L. was identified within the pollen samples. Rosa canina L. was the most commonly found of the 23 plant species identified in the pollen samples, suggesting that, in addition to providing a nesting resource for Megachile leafcutter bees, it may be an important forage plant for these species. Higher levels of connectance and nestedness were characteristic of pollen transport networks on farms with abundant floral resources, which may increase resilience to species loss. Our data suggest that plant species promoted currently by agri‐environment schemes are not optimal for solitary bee foraging. If a diverse community of pollinators is to be supported on UK and European farmland, additional species such as R. canina should be encouraged to meet the foraging requirements of solitary bees.     

Glycan recognition by human blood mononuclear cells with an emphasis on dendritic cells

Dendritic cells (DCs) play crucial roles in innate and adaptive immune response, for which reason targeting antigen to these cells is an important strategy for improvement of vaccine development. To this end, we explored recognition of DCs lectins by glycans. For selection of the glycan “vector”, a library of 229 fluorescent glycoprobes was employed to assess interaction with the CD14^low/-CD16⁺CD83⁺ blood mononuclear cell population containing the DCs known for their importance in antigen presentation to T-lymphocytes. It was found that: 1) the glycan-binding profiles of this CD14^low/-CD16⁺CD83⁺ subpopulation were similar but not identical to DCs of monocyte origin (moDCs); 2) the highest percentage of probe-positive cells in this CD14 ^low/-CD16⁺CD83⁺ subpopulation was observed for GalNAcα1-2Galβ (A_di), (Neu5Acα)₃ and three mannose-reach glycans; 3) subpopulation of CD14^low/-CD16⁺ cells preferentially bound 4’-O-Su-LacdiNAc. Considering the published data on specificity of DCs binding, the glycans showing particular selectivity for the CD14 ^low/-CD16⁺CD83⁺ cells are likely interacting with macrophage galactose binding lectin (MGL), siglec-7 and dectin-2. In contrast, DC-SIGN is not apparently involved, even in case of mannose-rich glycans. Taking into consideration potential in vivo competition between glycan “vectors” and glycans within glycocalyx, attempting to target vaccine to DCs glycan-binding receptors should focus on A_di and (Neu5Acα)₃ as the most promising vectors.