Nisin variants from Streptococcus and Staphylococcus successfully express in NZ9800.

AIMS: Increases in antimicrobial resistance have meant that the antimicrobial potential of lantibiotics is now being investigated irrespective of the nature of the producing organism. The aim of this study was to investigate whether natural nisin variants produced by non-Generally Recognized as Safe (GRAS) strains, such as nisin H, nisin J and nisin P, could be expressed in a well-characterized GRAS host. METHODS AND RESULTS: This study involved cloning the nisin A promoter and leader sequence fused to nisin H, nisin J or nisin P structural gene sequences originally produced by Streptococcus hyointestinalis DPC 6484, Staphylococcus capitis APC 2923 and Streptococcus agalactiae DPC 7040, respectively. This resulted in their expression in Lactococcus lactis NZ9800, a genetically modified strain that does not produce nisin A. CONCLUSIONS: Induction of the nisin controlled gene expression system demonstrates that these three nisin variants could be acted on by nisin A machinery provided by the host strain. SIGNIFICANCE AND IMPACT OF THE STUDY: Describes the first successful heterologous production of three natural nisin variants by a GRAS strain, and demonstrates how such systems could be harnessed not only for lantibiotic production but also in the expansion of their structural diversity and development for use as future biotherapeutics.

A Barrett's esophagus registry of over 1000 patients from a specialist center highlights greater risk of progression than population-based registries and high risk of low grade dysplasia.

Barrett's esophagus (BE) arising from chronic gastro-oesophageal reflux (GERD) is the main pathologic precursor of esophageal adenocarcinoma (EAC). The risk of progression to high-grade dysplasia (HGD) and EAC is unclear, and recent population studies from Denmark and Northern Ireland suggest that this has been overestimated in the past. No data exist from the Republic of Ireland. A detailed clinical, endoscopic, and pathologic database was established in one center as a proposed pilot for a national registry, and initial and follow-up data were abstracted by a data manager. One thousand ninety-three patients were registered, 60 patients with HGD were excluded, leaving 1033, with a median age of 59 and 2 : 1 male to female ratio, and 3599 person-years of follow-up. The overall incidence of HGD/EAC was 1.33% per year overall, 0.85% if the first year is excluded. Within the first year after index endoscopy, 18 cases of HGD or EAC were identified, and 30 following the first year. Low-grade dysplasia (LGD) on index endoscopy was associated with an incidence of progression of 6.5% per year, and 3.1% when tertiary referrals were excluded. These data provide important demographic and clinical information on the population of Irish patients with BE, with incidence rates of progression higher than recently published population-based registry series, perhaps relating to sampling and pathological assessment. Low-grade dysplasia on initial biopsy is a significant proxy marker of risk of progression.

The esophagitis to adenocarcinoma sequence; the role of inflammation.

Esophageal adenocarcinoma (EAC) is the eighth most common cancer worldwide, and approximately 15% of patients survive 5years. Reflux disease (GERD) and Barrett's esophagus (BE) are major risk factors for the development of EAC, and epidemiologic studies highlight a strong association with obesity. The immune, inflammatory and intracellular signaling changes resulting from chronic inflammation of the esophageal squamous epithelium are increasingly well characterized. In GERD and Barrett's, an essential role for T-cells in the initiation of inflammation in the esophagus has been identified, and a balance between T-cell responses and phenotype may play an important role in disease progression. Obesity is a chronic low-grade inflammatory state, fueled by adipose tissue derived- inflammatory mediators such as IL-6, TNF-α and leptin, representing a novel area for targeted research. Additionally, reactive oxygen species (ROS) and receptor tyrosine kinase (RTK) activation may drive progression from esophagitis to EAC, and downstream signaling pathways employed by these molecules may be important. This review will explain the diverse range of mechanisms potentially driving and maintaining inflammation within the esophagus and explore both existing and future therapeutic strategies targeting the process.

Kinetic quantitation of cerebral PET-FDG studies without concurrent blood sampling: statistical recovery of the arterial input function.

Kinetic quantitation of dynamic positron emission tomography (PET) studies via compartmental modeling usually requires the time-course of the radio-tracer concentration in the arterial blood as an arterial input function (AIF). For human and animal imaging applications, significant practical difficulties are associated with direct arterial sampling and as a result there is substantial interest in alternative methods that require no blood sampling at the time of the study. A fixed population template input function derived from prior experience with directly sampled arterial curves is one possibility. Image-based extraction, including requisite adjustment for spillover and recovery, is another approach. The present work considers a hybrid statistical approach based on a penalty formulation in which the information derived from a priori studies is combined in a Bayesian manner with information contained in the sampled image data in order to obtain an input function estimate. The absolute scaling of the input is achieved by an empirical calibration equation involving the injected dose together with the subject's weight, height and gender. The technique is illustrated in the context of (18)F -Fluorodeoxyglucose (FDG) PET studies in humans. A collection of 79 arterially sampled FDG blood curves are used as a basis for a priori characterization of input function variability, including scaling characteristics. Data from a series of 12 dynamic cerebral FDG PET studies in normal subjects are used to evaluate the performance of the penalty-based AIF estimation technique. The focus of evaluations is on quantitation of FDG kinetics over a set of 10 regional brain structures. As well as the new method, a fixed population template AIF and a direct AIF estimate based on segmentation are also considered. Kinetics analyses resulting from these three AIFs are compared with those resulting from radially sampled AIFs. The proposed penalty-based AIF extraction method is found to achieve significant improvements over the fixed template and the segmentation methods. As well as achieving acceptable kinetic parameter accuracy, the quality of fit of the region of interest (ROI) time-course data based on the extracted AIF, matches results based on arterially sampled AIFs. In comparison, significant deviation in the estimation of FDG flux and degradation in ROI data fit are found with the template and segmentation methods. The proposed AIF extraction method is recommended for practical use.

A class of amphipathic proteins associated with lipid storage bodies in plants. Possible similarities with animal serum apolipoproteins.

The lipid-storing tissues of plants contain many small (0.2-1 microns) lipid (normally triacylglycerol) droplets which are surrounded and stabilized by a mixed phospholipid and protein annulus. The proteinaceous components of the lipid storage bodies are termed oleosins and are not associated with any other cellular structures. The major oleosins of rapeseed and radish have been isolated by preparative SDS-PAGE and are respectively classes of 19 kDa and 20 kDa proteins. Both protein classes were N-terminally blocked for direct sequencing, but were partially sequenced following limited proteolytic digestion. The major rapeseed oleosin was made up of at least two 19 kDa polypeptides, termed nap-I and nap-II, which have closely related but different amino acid sequences. A single 20 kDa oleosin, termed rad-I, was found in radish. A near full length cDNA clone for a major rapeseed oleosin was sequenced and found to correspond almost exactly to the sequence of nap-II. The sequences of nap-I and rad-I show very close similarity to one another, as do the sequences of nap-II and the previously determined sequence for the major oleosin from maize. All four oleosins have a large central hydrophobic domain flanked by polar N- and C-terminal domains. Secondary structure predictions for the four oleosins are similar and a novel model is proposed based on a central hydrophobic beta-strand region flanked by an N-terminal polar alpha-helix and a C-terminal amphipathic alpha-helix. The possibility that oleosins exhibit structural and functional similarities with some animal apolipoproteins is discussed.