The derivation of the formyl-group oxygen of chlorophyll b in higher plants from molecular oxygen.

The mechanism of formation of the formyl group of chlorophyll b has long been obscure but, in this paper, the origin of the 7-formyl-group oxygen of chlorophyll b in higher plants was determined by greening etiolated maize leaves, excised from dark-grown plants, by illumination under white light in the presence of either H218O or 18O2 and examining the newly synthesized chlorophylls by mass spectroscopy. To minimize the possible loss of 18O label from the 7-formyl substituent by reversible formation of chlorophyll b-71-gem-diol (hydrate) with unlabelled water in the cell, the formyl group was reduced to a hydroxymethyl group during extraction with methanol containing NaBH4: chlorophyll a remained unchanged during this rapid reductive extraction process. Mass spectra of chlorophyll a and [7-hydroxymethyl]-chlorophyll b extracted from leaves greened in the presence of either H218O or 18O2 revealed that 18O was incorporated only from molecular oxygen but into both chlorophylls: the mass spectra were consistent with molecular oxygen providing an oxygen atom not only for incorporation into the 7-formyl group of chlorophyll b but also for the well-documented incorporation into the 131-oxo group of both chlorophylls a and b [see Walker, C. J., Mansfield, K. E., Smith, K. M. & Castelfranco, P. A. (1989) Biochem. J. 257, 599–602]. The incorporation of isotope led to as much as 77% enrichment of the 131-oxo group of chlorophyll a: assuming identical incorporation into the 131 oxygen of chlorophyll b, then enrichment of the 7-formyl oxygen was as much as 93%. Isotope dilution by re-incorporation of photosynthetically produced oxygen from unlabelled water was negligible as shown by a greening experiment in the presence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. The high enrichment using 18O2, and the absence of labelling by H218O, unequivocally demonstrates that molecular oxygen is the sole precursor of the 7-formyl oxygen of chlorophyll b in higher plants and strongly suggests a single pathway for the formation of the chlorophyll b formyl group involving the participation of an oxygenase-type enzyme

Origin of Saxitoxin Biosynthetic Genes in Cyanobacteria

BACKGROUND:Paralytic shellfish poisoning (PSP) is a potentially fatal syndrome associated with the consumption of shellfish that have accumulated saxitoxin (STX). STX is produced by microscopic marine dinoflagellate algae. Little is known about the origin and spread of saxitoxin genes in these under-studied eukaryotes. Fortuitously, some freshwater cyanobacteria also produce STX, providing an ideal model for studying its biosynthesis. Here we focus on saxitoxin-producing cyanobacteria and their non-toxic sisters to elucidate the origin of genes involved in the putative STX biosynthetic pathway. METHODOLOGY/PRINCIPAL FINDINGS:We generated a draft genome assembly of the saxitoxin-producing (STX+) cyanobacterium Anabaena circinalis ACBU02 and searched for 26 candidate saxitoxin-genes (named sxtA to sxtZ) that were recently identified in the toxic strain Cylindrospermopsis raciborskii T3. We also generated a draft assembly of the non-toxic (STX-) sister Anabaena circinalis ACFR02 to aid the identification of saxitoxin-specific genes. Comparative phylogenomic analyses revealed that nine putative STX genes were horizontally transferred from non-cyanobacterial sources, whereas one key gene (sxtA) originated in STX+ cyanobacteria via two independent horizontal transfers followed by fusion. In total, of the 26 candidate saxitoxin-genes, 13 are of cyanobacterial provenance and are monophyletic among the STX+ taxa, four are shared amongst STX+ and STX-cyanobacteria, and the remaining nine genes are specific to STX+ cyanobacteria. CONCLUSIONS/SIGNIFICANCE:Our results provide evidence that the assembly of STX genes in ACBU02 involved multiple HGT events from different sources followed presumably by coordination of the expression of foreign and native genes in the common ancestor of STX+ cyanobacteria. The ability to produce saxitoxin was subsequently lost multiple independent times resulting in a nested relationship of STX+ and STX- strains among Anabaena circinalis strains

A systematic review of high-fibre dietary therapy in diverticular disease

The exact pathogenesis of diverticular disease of the sigmoid colon is not well established. However, the hypothesis that a low-fibre diet may result in diverticulosis and a high-fibre diet will prevent symptoms or complications of diverticular disease is widely accepted. The aim of this review is to assess whether a high-fibre diet can improve symptoms and/or prevent complications of diverticular disease of the sigmoid colon and/or prevent recurrent diverticulitis after a primary episode. Clinical studies were eligible for inclusion if they assessed the treatment of diverticular disease or the prevention of recurrent diverticulitis with a high-fibre diet. The following exclusion criteria were used for study selection: studies without comparison of the patient group with a control group. No studies concerning prevention of recurrent diverticulitis with a high-fibre diet met our inclusion criteria. Three randomised controlled trials (RCT) and one case-control study were included in this systematic review. One RCT of moderate quality showed no difference in the primary endpoints. A second RCT of moderate quality and the case-control study found a significant difference in favour of a high-fibre diet in the treatment of symptomatic diverticular disease. The third RCT of moderate quality found a significant difference in favour of methylcellulose (fibre supplement). This study also showed a placebo effect. High-quality evidence for a high-fibre diet in the treatment of diverticular disease is lacking, and most recommendations are based on inconsistent level 2 and mostly level 3 evidence. Nevertheless, high-fibre diet is still recommended in several guideline

Discovery of Nuclear-Encoded Genes for the Neurotoxin Saxitoxin in Dinoflagellates

Saxitoxin is a potent neurotoxin that occurs in aquatic environments worldwide. Ingestion of vector species can lead to paralytic shellfish poisoning, a severe human illness that may lead to paralysis and death. In freshwaters, the toxin is produced by prokaryotic cyanobacteria; in marine waters, it is associated with eukaryotic dinoflagellates. However, several studies suggest that saxitoxin is not produced by dinoflagellates themselves, but by co-cultured bacteria. Here, we show that genes required for saxitoxin synthesis are encoded in the nuclear genomes of dinoflagellates. We sequenced >1.2×106 mRNA transcripts from the two saxitoxin-producing dinoflagellate strains Alexandrium fundyense CCMP1719 and A. minutum CCMP113 using high-throughput sequencing technology. In addition, we used in silico transcriptome analyses, RACE, qPCR and conventional PCR coupled with Sanger sequencing. These approaches successfully identified genes required for saxitoxin-synthesis in the two transcriptomes. We focused on sxtA, the unique starting gene of saxitoxin synthesis, and show that the dinoflagellate transcripts of sxtA have the same domain structure as the cyanobacterial sxtA genes. But, in contrast to the bacterial homologs, the dinoflagellate transcripts are monocistronic, have a higher GC content, occur in multiple copies, contain typical dinoflagellate spliced-leader sequences and eukaryotic polyA-tails. Further, we investigated 28 saxitoxin-producing and non-producing dinoflagellate strains from six different genera for the presence of genomic sxtA homologs. Our results show very good agreement between the presence of sxtA and saxitoxin-synthesis, except in three strains of A. tamarense, for which we amplified sxtA, but did not detect the toxin. Our work opens for possibilities to develop molecular tools to detect saxitoxin-producing dinoflagellates in the environment

Costs of raccoon rabies incidents in cattle herds in Hampshire County, West Virginia, and Guernsey County, Ohio

Objective—To determine direct and indirect costs associated with raccoon rabies incidents involving cattle herds in Hampshire County, WV, in 2008 and Guernsey County, Ohio, in 2010. Design—Ex post cost analysis. Animals—1 cattle herd in Hampshire County, WV, in 2008 and 1 cattle herd in Guernsey County, Ohio, in 2010. Procedures—Data were collected for each incident through telephone and email interviews with 16 federal, state, and county agency personnel involved in the case investigations and coordinated responses for rabies in the cattle herds. To characterize the economic impact associated with rabies in the 2 cattle herds, cost analysis was conducted with 7 cost variables (salary and benefits for personnel involved in the response, human postexposure prophylaxis, indirect patient costs, rabies diagnostic testing, cattle carcass disposal, market value of euthanized cattle, and enhanced rabies surveillance). Estimates of direct costs were determined on the basis of agency records and other relevant data obtained from notes and reports made by agency staff at the time of the incident and from a review of the literature. Results—Primary costs included the market value of euthanized cattle ($51,461 in West Virginia;$12,561 in Ohio), human postexposure prophylaxis ($17,959 in West Virginia;$11,297 in Ohio), and salary and benefits for personnel involved in the response ($19,792 in West Virginia;$14,496 in Ohio). Conclusions and Clinical Relevance—These results should provide a basis for better characterization of the economic impact of wildlife rabies in cattle in the United States. (J Am Vet Med Assoc 2013;243:1561–1567

CE IGCC repowering project: Materials for coal gasification environment. Topical report, June 1993

A task to develop material requirements and a materials testing strategy was established with the Materials and Water Chemistry Department of the ABB Power plant Laboratories. This involved examining the requirements for each system under ABB CE scope. The basis for the material recommendations was largely based on in-house test programs under DOE contract and ABB CE experience. Consultants were utilized in a parallel task to assist in the design and material specification for the solids handling systems. ABB CE experience includes operating data from a former process development unit (PDU) located in Windsor, Connecticut. The unit gasified Pittsburgh seam coal at a nominal firing rate of 120 tons per day. The objectives of the program were to produce clean, low-Btu gas from coal, and to provide the design information for scale-up to commercial-size plants. The results of the task were used to specify and, depending on scope, design the equipment used in the plant. A detailed document was developed and used to generate a Metallurgical Flow Diagram. Specifications were developed from this diagram. For the equipment designed, these selections were provided to representatives of cognizant design and manufacturing departments. In addition, where appropriate, recommendations were made for operating procedures and for design changes. Specified materials will be again evaluated during detailed engineering. In some areas the results of the task were not conclusive. Additional investigation will be required. These areas are the types of approaches which can be taken to accommodate product gas sulfidation resistance and solids transport erosion

Factors Influencing the Application of a Biopsychosocial Perspective in Clinical Judgement of Chronic Pain: Interactive Management with Medical Students

Background: Though there is wide support for the application of biopsychosocial perspectives in clinical judgement of chronic pain cases, such perspectives are often overlooked due to either inadequate training or attitudes favoring a biomedical approach. Recent research has indicated that despite such explanations, both established general practitioners (GP) and medical students account for some psychosocial factors when making clinical judgements regarding chronic pain cases, but report not being likely to apply these in real-world, clinical settings due to numerous factors, including available time with patients. Thus, it is evident that a greater understanding of clinical judgement-making processes and the factors that affect application of these processes is required, particularly regarding chronic pain.Objectives: The aims of the current study were to investigate medical students’ conceptualizations of the factors that influence application of a biopsychosocial approach to clinical judgement-making incases of chronic pain using interactive management (IM), model the relationships among these factors, and make recommendations to chronic pain treatment policy in light of the findings.Study Design: The current study used IM to identify and model factors that influence the application of a biopsychosocial approach to clinical judgement-making in cases of chronic pain, based on medical students’ conceptualizations of these factors.Setting: Two university classrooms.Methods: IM is a systems thinking and action mapping strategy used to aid groups in developing outcomes regarding complex issues, through integrating contributions from individuals with diverse views, backgrounds, and perspectives. IM commonly utilizes the nominal group technique and interpretive structural modeling, which in this context were employed to help medical students identify, clarify, and model influences on the application of biopsychosocial perspectives in treating chronic pain patients.Results: Results of IM group work revealed 7 core biopsychosocial approach application categories: GP attitudes, cost, GP knowledge, time, patient-doctor relationship, biomedical factors. and patient perception. GP attitudes was the most critical driver of all other competencies in the system, with cost and GP knowledge revealed as secondary drivers.Limitations: Potential differences in level of prior biopsychosocial perspective knowledge across participants and a potentially small sample size (though consistent with past research and appropriate for an exploratory study of this nature – for purposes of achieving the depth and richness of the deliberation and qualitative insights revealed by participants using the IM methodology).Conclusions: Results from this study may be used to both recommend further research on the identified factors influencing application of biopsychosocial perspectives in treatment of chronic pain and support amendment to extant health care policy, particularly with respect to cost, GP attitudes, and knowledge. Though this research claims neither that the influences identified are the only influences on biopsychosocial application, nor the order of their importance, the research does contribute to an ongoing effort to better understand the factors that influence doctors in their treatment of chronic pain