Cellulosic biomass is an abundant and underused substrate for biofuel production. The inability of many microbes to metabolize the pentose sugars abundant within hemicellulose creates specific ...challenges for microbial biofuel production from cellulosic material. Although engineered strains of Saccharomyces cerevisiae can use the pentose xylose, the fermentative capacity pales in comparison with glucose, limiting the economic feasibility of industrial fermentations. To better understand xylose utilization for subsequent microbial engineering, we sequenced the genomes of two xylose-fermenting, beetle-associated fungi, Spathaspora passalidarum and Candida tenuis. To identify genes involved in xylose metabolism, we applied a comparative genomic approach across 14 Ascomycete genomes, mapping phenotypes and genotypes onto the fungal phylogeny, and measured genomic expression across five Hemiascomycete species with different xylose-consumption phenotypes. This approach implicated many genes and processes involved in xylose assimilation. Several of these genes significantly improved xylose utilization when engineered into S. cerevisiae, demonstrating the power of comparative methods in rapidly identifying genes for biomass conversion while reflecting on fungal ecology.
Background Stereotactic breast biopsies have become the gold standard for tissue diagnosis in non-palpable, sonographically occult breast abnormalities seen on mammogram. Only limited data exist in ...South Africa on the correlation between imaging findings and stereotactic biopsy histology.Objectives To describe the mammographic findings and histological diagnosis in patients who underwent stereotactic breast biopsy at a referral hospital. In addition, to evaluate the proportion of malignancy in each Breast Imaging Reporting and Data System (BI-RADS) category.Method A retrospective review of stereotactic breast biopsies was performed. Imaging characteristics (including BI-RADS category) and histological diagnosis were recorded. Using histopathology, cases were classified as benign, high-risk or malignant.Results A total of 131 biopsies, from 123 patients, were included in the study. Most biopsies were performed on asymptomatic patients (79.3%, 104/131). The majority were categorised as BI-RADS 4 and demonstrated calcifications. Histology revealed a malignant diagnosis in 40 (30.5%) patients, a high-risk lesion in 8 (6.1%) patients and a benign diagnosis in 83 (63.4%) patients. There was a stepwise increase in the proportion of malignancy from BI-RADS category 3 to 5. When compared with surgical histology, the stereotactic biopsies demonstrated an overall ductal carcinoma in situ (DCIS) underestimation rate of 10.3%.Conclusion Despite resource restrictions, stereotactic breast biopsies performed in a South African context produce radiological-pathological concordance in keeping with BI-RADS guidelines, as well as with local and international studies.
Background
Lymphobronchial tuberculosis (TB) is tuberculous lymphadenopathy involving the airways, which is particularly common in children.
Objective
To describe CT findings of lymphobronchial TB in ...children, the parenchymal complications and associated abnormalities.
Materials and methods
CT scans of children with lymphobronchial TB were reviewed retrospectively. Lymphadenopathy, bronchial narrowing, parenchymal complications and associations were documented.
Results
Infants comprised 51% of patients. The commonest site of lymphadenopathy was the subcarinal mediastinum (97% of patients). Bronchial compression was seen in all children (259 bronchi, of these 28% the bronchus intermedius) with severe or complete stenosis in 23% of affected bronchi. Parenchymal complications were present in 94% of patients, including consolidation (88%), breakdown (42%), air trapping (38%), expansile pneumonia (28%), collapse (17%) and bronchiectasis (9%), all predominantly on the right side (63%). Associated abnormalities included ovoid lesions, miliary nodules, pleural disease and intracavitary bodies.
Conclusion
Airway compression was more severe in infants and most commonly involved the bronchus intermedius. Numerous parenchymal complications were documented, all showing right-side predominance.
Methanomicrobiales is the least studied order of methanogens. While these organisms appear to be more closely related to the Methanosarcinales in ribosomal-based phylogenetic analyses, they are ...metabolically more similar to Class I methanogens.
In order to improve our understanding of this lineage, we have completely sequenced the genomes of two members of this order, Methanocorpusculum labreanum Z and Methanoculleus marisnigri JR1, and compared them with the genome of a third, Methanospirillum hungatei JF-1. Similar to Class I methanogens, Methanomicrobiales use a partial reductive citric acid cycle for 2-oxoglutarate biosynthesis, and they have the Eha energy-converting hydrogenase. In common with Methanosarcinales, Methanomicrobiales possess the Ech hydrogenase and at least some of them may couple formylmethanofuran formation and heterodisulfide reduction to transmembrane ion gradients. Uniquely, M. labreanum and M. hungatei contain hydrogenases similar to the Pyrococcus furiosus Mbh hydrogenase, and all three Methanomicrobiales have anti-sigma factor and anti-anti-sigma factor regulatory proteins not found in other methanogens. Phylogenetic analysis based on seven core proteins of methanogenesis and cofactor biosynthesis places the Methanomicrobiales equidistant from Class I methanogens and Methanosarcinales.
Our results indicate that Methanomicrobiales, rather than being similar to Class I methanogens or Methanomicrobiales, share some features of both and have some unique properties. We find that there are three distinct classes of methanogens: the Class I methanogens, the Methanomicrobiales (Class II), and the Methanosarcinales (Class III).
Background Globally, adults presenting with seizures account for 1% – 2% of visits to emergency departments (EDs), of which 25% are new-onset seizures. Neuroimaging is essential as part of the ...initial workup. Multiple studies have demonstrated abnormal CT brain (CTB) findings in these patients.Objectives To review the CTB findings in adults presenting with new-onset seizures in a resource restricted setting.Method A retrospective review of 531 CTBs was conducted at a tertiary hospital in Gauteng on adults presenting to the ED with new-onset seizures.Results The mean age of the patients was 45.6 ± 17.1 years, and the male to female ratio was 1.2:1. Generalised and focal seizure types were almost equally represented. Of the total 531 patients, 168 (31.6%) were HIV positive. The CTB findings were abnormal in 257 (48.4%) patients, albeit vascular pathology accounted for 21.9%. Infective pathology accounted for 14.1% with a statistically significant association with HIV (p = 0.003). Trauma related pathology was 2.4%, whilst neoplastic pathology was seen in 3.0%. Other causes included congenital pathology, calcifications, atrophy and gliosis. Clinical factors associated with abnormal CTB findings were age ≥ 40 years, HIV infection, hypertension, focal seizures, low Glasgow Coma Scale (GCS), raised cerebrospinal fluid (CSF) protein and presence of lymphocytes.Conclusion A high yield of abnormal CTB findings was noted in adult patients who presented with new-onset seizures, supporting the use of urgent CTB in patients with certain clinical risk factors. Patients without these risk factors can be scanned within 24–48 h in a resource restricted setting.
Purpose - This paper aims to examine the extent to which intellectual capital (IC) adds value to a service provider and presents an approach for interpreting the results.Design methodology approach - ...The value added intellectual coefficient (VAIC™) model is used to determine the relevant elements of intellectual capital because it employs existing financial data. The number of subjects was restricted to two companies operating in the Australian hotel industry over a four-year period (2004-2007).Findings - The VAIC™ model provides a robust tool for assessing the efficient use of intellectual capital. The model can be used by management to assess their own organisation's performance without having to rely upon industry standards.Research limitations implications - The data derived from published financial statements and the limitations associated with accounting standards may be questionable. However, the financial statements were subject to external audit verification. The restricted number of companies is a limitation to generalisability. However, the two companies are the major players in the Australian hotel industry.Practical implications - The application of the VAIC™ model presented in this paper provides a basis for practical application for management.Originality value - The study provides management with a guide to employing the VAIC™ model and, more importantly, a method for interpreting the results.
The complete DNA sequence of the aerobic cellulolytic soil bacterium Cytophaga hutchinsonii, which belongs to the phylum Bacteroidetes, is presented. The genome consists of a single, circular, ...4.43-Mb chromosome containing 3,790 open reading frames, 1,986 of which have been assigned a tentative function. Two of the most striking characteristics of C. hutchinsonii are its rapid gliding motility over surfaces and its contact-dependent digestion of crystalline cellulose. The mechanism of C. hutchinsonii motility is not known, but its genome contains homologs for each of the gld genes that are required for gliding of the distantly related bacteroidete Flavobacterium johnsoniae. Cytophaga-Flavobacterium gliding appears to be novel and does not involve well-studied motility organelles such as flagella or type IV pili. Many genes thought to encode proteins involved in cellulose utilization were identified. These include candidate endo-β-1,4-glucanases and β-glucosidases. Surprisingly, obvious homologs of known cellobiohydrolases were not detected. Since such enzymes are needed for efficient cellulose digestion by well-studied cellulolytic bacteria, C. hutchinsonii either has novel cellobiohydrolases or has an unusual method of cellulose utilization. Genes encoding proteins with cohesin domains, which are characteristic of cellulosomes, were absent, but many proteins predicted to be involved in polysaccharide utilization had putative D5 domains, which are thought to be involved in anchoring proteins to the cell surface.
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