A molecular assessment of the iron stress response in the two phylogenetic clades of Trichodesmium

Trichodesmium spp. play key roles in global carbon and nitrogen budgets and thus defining what controls their productivity is important for understanding climate change. While iron availability has been shown to be an important chemical factor for controlling both growth and nitrogen fixation rates in Trichodesmium , all culture experiments to date have focused solely on representatives from one clade of Trichodesmium . Genomic sequence analysis determined that the Trichodesmium erythraeum (IMS101) genome contains many of the archetypical genes involved in the prokaryotic iron stress response. Focusing on three of these genes, isiB , idiA and feoB , we found that all three showed an iron stress response in axenic T. erythraeum (IMS101), and their sequences were well conserved across four species in our Trichodesmium culture collection [consisting of two T. erythraeum strains (IMS101 and GBRTRLI101), two Trichodesmium tenue strains (Z-1 and H9-4), Trichodesmium thiebautii and Trichodesmium spiralis ]. With clade-specific quantitative PCR (qPCR) primers for one of these genes, isiB , we found that high isiB expression at low Fe levels corresponded to specific reductions in N₂ fixation rates in both major phylogenetic clades of Trichodesmium (the T. erythraeum clade and T. tenue clade). With regard to the two clades, the most significant difference determined was temperature optima, while more subtle differences in growth, N₂ fixation rate and gene expression responses to Fe stress were also observed. However the apparent conservation of the Fe stress response in the Trichodesmium genus suggests that it is an important adaptation for their niche in the oligotrophic ocean.     

A large web-based observer reliability study of early ischaemic signs on computed tomography. The Acute Cerebral CT Evaluation of Stroke Study (ACCESS)

Background

Early signs of ischaemic stroke on computerised tomography (CT) scanning are subtle but CT is the most widely available diagnostic test for stroke. Scoring methods that code for the extent of brain ischaemia may improve stroke diagnosis and quantification of the impact of ischaemia.

Methodology and Principal Findings

We showed CT scans from patients with acute ischaemic stroke (n = 32, with different patient characteristics and ischaemia signs) to doctors in stroke-related specialties world-wide over the web. CT scans were shown twice, randomly and blindly. Observers entered their scan readings, including early ischaemic signs by three scoring methods, into the web database. We compared observers'' scorings to a reference standard neuroradiologist using area under receiver operator characteristic curve (AUC) analysis, Cronbach''s alpha and logistic regression to determine the effect of scales, patient, scan and observer variables on detection of early ischaemic changes. Amongst 258 readers representing 33 nationalities and six specialties, the AUCs comparing readers with the reference standard detection of ischaemic signs were similar for all scales and both occasions. Being a neuroradiologist, slower scan reading, more pronounced ischaemic signs and later time to CT all improved detection of early ischaemic signs and agreement on the rating scales. Scan quality, stroke severity and number of years of training did not affect agreement.

Conclusions

Large-scale observer reliability studies are possible using web-based tools and inform routine practice. Slower scan reading and use of CT infarct rating scales improve detection of acute ischaemic signs and should be encouraged to improve stroke diagnosis.     

A local pancreatic renin-angiotensin system: endocrine and exocrine roles

The renin-angiotensin system (RAS) is classically characterized as a circulating hormonal system primarily through the production of the physiologically active product angiotensin II (Ang II) that plays a crucial role in the regulation of blood pressure, fluid and electrolyte homeostasis. In addition to this circulating RAS, numerous tissues and organs have been recently demonstrated to exhibit their own RAS products and activities. Such an intrinsic RAS can modulate the specific local functions of their respective tissues and organs, frequently in a paracrine and autocrine manner. Recent findings from our laboratories and others have made a significant contribution on the expression, localization, regulation, and potential role of a local RAS in the pancreas. Although, it is quite intriguing that components of the local pancreatic RAS are responsive to various physiological and pathophysiological conditions, the crucial role of this system in regulating the exocrine and endocrine functions and ultimately the clinical relevance to pancreatic disease is still largely equivocal. Of particular interest in this context are the actions of pancreatic RAS on the growth, anti-proliferation and free radical generation in the pancreas. The aims of the current article focus on the emerging data on the local pancreatic RAS; its involvement in exocrine acinar and endocrine islet aspects, and the clinical significance in the pancreas are particularly addressed. The target for the local pancreatic RAS may provide a new insight into future management of various clinical conditions including islet transplants, diabetes mellitus, pancreatic cancer, pancreatitis and cystic fibrosis.     

Associations between Intimate Partner Violence and Termination of Pregnancy: A Systematic Review and Meta-Analysis

Background

Intimate partner violence (IPV) and termination of pregnancy (TOP) are global health concerns, but their interaction is undetermined. The aim of this study was to determine whether there is an association between IPV and TOP.

Methods and Findings

A systematic review based on a search of Medline, Embase, PsycINFO, and Ovid Maternity and Infant Care from each database''s inception to 21 September 2013 for peer-reviewed articles of any design and language found 74 studies regarding women who had undergone TOP and had experienced at least one domain (physical, sexual, or emotional) of IPV. Prevalence of IPV and association between IPV and TOP were meta-analysed. Sample sizes ranged from eight to 33,385 participants. Worldwide, rates of IPV in the preceding year in women undergoing TOP ranged from 2.5% to 30%. Lifetime prevalence by meta-analysis was shown to be 24.9% (95% CI 19.9% to 30.6%); heterogeneity was high (I ²>90%), and variation was not explained by study design, quality, or size, or country gross national income per capita. IPV, including history of rape, sexual assault, contraceptive sabotage, and coerced decision-making, was associated with TOP, and with repeat TOPs. By meta-analysis, partner not knowing about the TOP was shown to be significantly associated with IPV (pooled odds ratio 2.97, 95% CI 2.39 to 3.69). Women in violent relationships were more likely to have concealed the TOP from their partner than those who were not. Demographic factors including age, ethnicity, education, marital status, income, employment, and drug and alcohol use showed no strong or consistent mediating effect. Few long-term outcomes were studied. Women welcomed the opportunity to disclose IPV and be offered help. Limitations include study heterogeneity, potential underreporting of both IPV and TOP in primary data sources, and inherent difficulties in validation.

Conclusions

IPV is associated with TOP. Novel public health approaches are required to prevent IPV. TOP services provide an opportune health-based setting to design and test interventions. Please see later in the article for the Editors'' Summary     

Activating natural product synthesis using CRISPR interference and activation systems in Streptomyces

The rise of antibiotic-resistant bacteria represents a major threat to global health, creating an urgent need to discover new antibiotics. Natural products derived from the genus Streptomyces represent a rich and diverse repertoire of chemical molecules from which new antibiotics are likely to be found. However, a major challenge is that the biosynthetic gene clusters (BGCs) responsible for natural product synthesis are often poorly expressed under laboratory culturing conditions, thus preventing the isolation and screening of novel chemicals. To address this, we describe a novel approach to activate silent BGCs through rewiring endogenous regulation using synthetic gene regulators based upon CRISPR-Cas. First, we refine CRISPR interference (CRISPRi) and create CRISPR activation (CRISPRa) systems that allow for highly programmable and effective gene repression and activation in Streptomyces. We then harness these tools to activate a silent BGC by perturbing its endogenous regulatory network. Together, this work advances the synthetic regulatory toolbox for Streptomyces and facilitates the programmable activation of silent BGCs for novel chemical discovery.     

Characterization by high performance liquid chromatography of angiotensin peptides in the plasma and cerebrospinal fluid of the dog

A high performance liquid chromatography (HPLC) method is described for the separation of angiotensin (Ang) peptides and their subsequent quantification by radioimmunoassay in plasma and cerebrospinal fluid (CSF). The use of the ion-pair solvent heptafluorobutyric acid in gradient HPLC achieves baseline resolution of Ang I, Ang II, and the C-terminal fragments des-[Asp1]-Ang I, des-[Asp1]-Ang II, des-[Asp1,Arg2]-Ang II and des-[Asp1,Arg2,Val3]-Ang II in approximately 25 min. Recovery of synthetic Ang standards after phenylsilica extraction and HPLC separation was greater than 70% for each peptide in both plasma and CSF. Ang I and Ang II were shown to be the major immunoreactive Ang components in plasma, and Ang II, des-[Asp1,Arg2]-Ang II and des-[Asp1,Arg2,Val3]-Ang II in CSF.