Evaluation of appendicitis risk prediction models in adults with suspected appendicitis

Background Appendicitis is the most common general surgical emergency worldwide, but its diagnosis remains challenging. The aim of this study was to determine whether existing risk prediction models can reliably identify patients presenting to hospital in the UK with acute right iliac fossa (RIF) pain who are at low risk of appendicitis. Methods A systematic search was completed to identify all existing appendicitis risk prediction models. Models were validated using UK data from an international prospective cohort study that captured consecutive patients aged 16–45 years presenting to hospital with acute RIF in March to June 2017. The main outcome was best achievable model specificity (proportion of patients who did not have appendicitis correctly classified as low risk) whilst maintaining a failure rate below 5 per cent (proportion of patients identified as low risk who actually had appendicitis). Results Some 5345 patients across 154 UK hospitals were identified, of which two‐thirds (3613 of 5345, 67·6 per cent) were women. Women were more than twice as likely to undergo surgery with removal of a histologically normal appendix (272 of 964, 28·2 per cent) than men (120 of 993, 12·1 per cent) (relative risk 2·33, 95 per cent c.i. 1·92 to 2·84; P < 0·001). Of 15 validated risk prediction models, the Adult Appendicitis Score performed best (cut‐off score 8 or less, specificity 63·1 per cent, failure rate 3·7 per cent). The Appendicitis Inflammatory Response Score performed best for men (cut‐off score 2 or less, specificity 24·7 per cent, failure rate 2·4 per cent). Conclusion Women in the UK had a disproportionate risk of admission without surgical intervention and had high rates of normal appendicectomy. Risk prediction models to support shared decision‐making by identifying adults in the UK at low risk of appendicitis were identified

OPTIMIZATION OF GAMMA-PGA BIOSYNTHESIS SUPPORTED BY SYNTHETIC BIOLOGY AND METABOLIC ENGINEERING STRATEGIES

Poly-γ-glutamate (γ-PGA) is a natural polymer made of glutamic acid residues, synthesized by the pgs operon of Bacillus subtilis. γ-PGA has a wide range of applications as food, cosmetics and pharmaceutical additive. However, to increase its industrial attractiveness, it is necessary to cut production costs utilizing cost-competitive feedstocks for fermentation. Raw glycerol is a low-cost by-product of biodiesel plants (it accounts for 10% of the final product) that can be used as feedstock. To achieve cost-competitive γ-PGA production from glycerol a multifaceted approach has been set up that includes: 1) Characterization and optimization of pgs operon regulation: the strength of the pgs operon regulatory elements has been analysed both by a synthetic biology approach, exploiting the well-characterized expression operating unit (EOU) inserted in amyE, and by a classical in-locus transcriptional fusion. Results from the two settings will be compared. These data will now be used to finely tune pgs expression through an inducible promoter to optimize γ-PGA yield. 2) Accumulation of γ-PGA precursors by metabolic engineering: a genome-scale metabolic model was used to identify suitable targets for enhancing central carbon pathway flux toward γ-PGA synthesis. The first two B. subtilis strains, engineered according to this analysis, showed enhanced polymer production. Other target genes are under investigation. 3) Enhancement of glycerol metabolism: B. subtilis tolerance to raw glycerol obtained from a biodiesel plant (from both vegetable and animal origin) was verified. Further investigations are underway to improve glycerol uptake and consumption

A BioBrick-compatible Vector for Allelic Replacement Using the XylE Gene as Selection Marker

BACKGROUND: Circular plasmid-mediated homologous recombination is commonly used for marker-less allelic replacement, exploiting the endogenous recombination machinery of the host. Common limitations of existing methods include high false positive rates due to mutations in counter-selection genes, and limited applicability to specific strains or growth media. Finally, solutions compatible with physical standards, such as the BioBrick™, are not currently available, although they proved to be successful in the design of other replicative or integrative plasmids. FINDINGS: We illustrate pBBknock, a novel BioBrick™-compatible vector for allelic replacement in Escherichia coli. It includes a temperature-sensitive replication origin and enables marker-less genome engineering via two homologous recombination events. Chloramphenicol resistance allows positive selection of clones after the first event, whereas a colorimetric assay based on the xylE gene provides a simple way to screen clones in which the second recombination event occurs. Here we successfully use pBBknock to delete the lactate dehydrogenase gene in E. coli W, a popular host used in metabolic engineering. CONCLUSIONS: Compared with other plasmid-based solutions, pBBknock has a broader application range, not being limited to specific strains or media. We expect that pBBknock will represent a versatile solution both for practitioners, also among the iGEM competition teams, and for research laboratories that use BioBrick™-based assembly procedures. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12575-016-0036-z) contains supplementary material, which is available to authorized users

Engineering endogenous fermentative routes in ethanologenic Escherichia coli W for bioethanol production from concentrated whey permeate

https://www.sciencedirect.com/science/article/pii/S1871678420300911?via=ihu