Nitrification potentials of benthic macrofaunal tubes and burrow walls: effects of sediment NH4+ and animal irrigation behavior

We examined the natural variation of nitrification potentials (NPs) of surface sediments and macrofaunal tubes and burrow walls in relation to sediment NH4+ level, season, and macrofaunal species. NP (the ability of a unit of sediment to oxidize NH4+ when NH4+ and O-2 are not limiting) is an index of the abundance and activity of nitrifying bacteria which we measured in slurries with the chlorate block technique (nmol NO2--N produced g(-1) dry weight sediment h(-1)). The NP of the tubes of the polychaete Loimia medusa was positively related to sediment NH4+ (KCl-extractable) concentration at 3 sites where tubes were collected in June 1990 (Spearman rank correlation coefficient I-s = 0.90, p = 0.03), as was the NP of surface (0 to 1 cm) sediment (I-2 = 0.92, p = 0.002). The degree to which tube NP exceeded the NP of surface sediment was, however, negatively associated with sediment NH4+ (I-s = -0.84, p = 0.05). Tube NP of L. medusa did not vary significantly with date (February, April, and June 1990). Tubes or burrow walls of Macoma balthica (bivalve), Leptocheirus plumulosus (amphipod), and the polychaetes Macroclymene zonalis, Pectinaria gouldii, L. medusa, and Diopatra cuprea had NPs significantly greater (2 to 20 times) than that of adjacent sediment from the same depth interval, indicating that these species stimulated nitrification. Except for burrows of M. balthica, the NPs of these structures were significantly (p less than or equal to 0.05) greater (1.5 to 61 times) than that of surface sediment. The duration of macrofaunal irrigation activity, but not irrigation rate, was positively associated (I-s = 0.72, p = 0.01) with the enhancement of NP in tubes and burrow walls relative to surface sediment. These findings indicate that macrofaunal tubes and burrows tend to be sites of enhanced NP and that this enhancement varies among species due to Variations in irrigation behavior. The NP of macrofaunal structures also varies among sites in relation to sediment NH4+ concentrations

Differential modulation of microglia superoxide anion and thromboxane B(2 )generation by the marine manzamines

BACKGROUND: Thromboxane B(2 )(TXB(2)) and superoxide anion (O(2)(-)) are neuroinflammatory mediators that appear to be involved in the pathogenesis of several neurodegenerative diseases. Because activated-microglia are the main source of TXB(2 )and O(2)(- )in these disorders, modulation of their synthesis has been hypothesized as a potential therapeutic approach for neuroinflammatory disorders. Marine natural products have become a source of novel agents that modulate eicosanoids and O(2)(- )generation from activated murine and human leukocytes. With the exception of manzamine C, all other manzamines tested are characterized by a complex pentacyclic diamine linked to C-1 of the β-carboline moiety. These marine-derived alkaloids have been reported to possess a diverse range of bioactivities including anticancer, immunostimulatory, insecticidal, antibacterial, antimalarial and antituberculosis activities. The purpose of this investigation was to conduct a structure-activity relationship study with manzamines (MZ) A, B, C, D, E and F on agonist-stimulated release of TXB(2 )and O(2)(- )from E. coli LPS-activated rat neonatal microglia in vitro. RESULTS: The manzamines differentially attenuated PMA (phorbol 12-myristate 13-acetate)-stimulated TXB(2 )generation in the following order of decreasing potency: MZA (IC(50 )<0.016 μM) >MZD (IC(50 )= 0.23 μM) >MZB (IC(50 )= 1.6 μM) >MZC (IC(50 )= 2.98 μM) >MZE and F (IC(50 )>10 μM). In contrast, there was less effect on OPZ (opsonized zymosan)-stimulated TXB(2 )generation: MZB (IC(50 )= 1.44 μM) >MZA (IC(50 )= 3.16 μM) >MZC (IC(50 )= 3.34 μM) >MZD, MZE and MZF (IC(50 )>10 μM). Similarly, PMA-stimulated O(2)(- )generation was affected differentially as follows: MZD (apparent IC(50)<0.1 μM) >MZA (IC(50 )= 0.1 μM) >MZB (IC(50 )= 3.16 μM) >MZC (IC(50 )= 3.43 μM) >MZE and MZF (IC(50 )>10 μM). In contrast, OPZ-stimulated O(2)(- )generation was minimally affected: MZB (IC(50 )= 4.17 μM) >MZC (IC(50 )= 9.3 μM) >MZA, MZD, MZE and MZF (IC(50 )> 10 μM). From the structure-activity relationship perspective, contributing factors to the observed differential bioactivity on TXB(2 )and O(2)(- )generation are the solubility or ionic forms of MZA and D as well as changes such as saturation or oxidation of the β carboline or 8-membered amine ring. In contrast, the fused 13-membered macrocyclic and isoquinoline ring system, and any substitutions in these rings would not appear to be factors contributing to bioactivity. CONCLUSION: To our knowledge, this is the first experimental study that demonstrates that MZA, at in vitro concentrations that are non toxic to E. coli LPS-activated rat neonatal microglia, potently modulates PMA-stimulated TXB(2 )and O(2)(- )generation. MZA may thus be a lead candidate for the development of novel therapeutic agents for the modulation of TXB(2 )and O(2)(- )release in neuroinflammatory diseases. Marine natural products provide a novel and rich source of chemical diversity that can contribute to the design and development of new and potentially useful anti-inflammatory agents to treat neurodegenerative diseases

Gut thinking: the gut microbiome and mental health beyond the head

Background: In recent decades, dominant models of mental illness have become increasingly focused on the head, with mental disorders being figured as brain disorders. However, research into the active role that the microbiome-gut-brain axis plays in affecting mood and behaviour may lead to the conclusion that mental health is more than an internalised problem of individual brains. Objective: This article explores the implications of shifting understandings about mental health that have come about through research into links between the gut microbiome and mental health problems such as depression and anxiety. It aims to analyse the different ways that the lines between mind and body and mental and physical health are re-shaped by this research, which is starting to inform clinical and public understanding. Design: As mental health has become a pressing issue of political and public concern it has become increasingly constructed in socio-cultural and personal terms beyond clinical spaces, requiring a conceptual response that exceeds biomedical inquiry. This article argues that an interdisciplinary critical medical humanities approach is well positioned to analyse the impact of microbiome-gut-brain research on conceptions of mind. Results: The entanglement of mind and matter evinced by microbiome-gut-brain axis research potentially provides a different way to conceptualise the physical and social concomitants of mental distress. Conclusion: Mental health is not narrowly located in the head but is assimilated by the physical body and intermingled with the natural world, requiring different methods of research to unfold the meanings and implications of gut thinking for conceptions of human selfhood

Electronic stress tensor analysis of hydrogenated palladium clusters

We study the chemical bonds of small palladium clusters Pd_n (n=2-9) saturated by hydrogen atoms using electronic stress tensor. Our calculation includes bond orders which are recently proposed based on the stress tensor. It is shown that our bond orders can classify the different types of chemical bonds in those clusters. In particular, we discuss Pd-H bonds associated with the H atoms with high coordination numbers and the difference of H-H bonds in the different Pd clusters from viewpoint of the electronic stress tensor. The notion of "pseudo-spindle structure" is proposed as the region between two atoms where the largest eigenvalue of the electronic stress tensor is negative and corresponding eigenvectors forming a pattern which connects them.Comment: 22 pages, 13 figures, published online, Theoretical Chemistry Account

Home parenteral nutrition with an omega-3-fatty-acid-enriched MCT/LCT lipid emulsion in patients with chronic intestinal failure (the HOME study):study protocol for a randomized, controlled, multicenter, international clinical trial

BACKGROUND: Home parenteral nutrition (HPN) is a life-preserving therapy for patients with chronic intestinal failure (CIF) indicated for patients who cannot achieve their nutritional requirements by enteral intake. Intravenously administered lipid emulsions (ILEs) are an essential component of HPN, providing energy and essential fatty acids, but can become a risk factor for intestinal-failure-associated liver disease (IFALD). In HPN patients, major effort is taken in the prevention of IFALD. Novel ILEs containing a proportion of omega-3 polyunsaturated fatty acids (n-3 PUFA) could be of benefit, but the data on the use of n-3 PUFA in HPN patients are still limited. METHODS/DESIGN: The HOME study is a prospective, randomized, controlled, double-blind, multicenter, international clinical trial conducted in European hospitals that treat HPN patients. A total of 160 patients (80 per group) will be randomly assigned to receive the n-3 PUFA-enriched medium/long-chain triglyceride (MCT/LCT) ILE (Lipidem/Lipoplus® 200 mg/ml, B. Braun Melsungen AG) or the MCT/LCT ILE (Lipofundin® MCT/LCT/Medialipide® 20%, B. Braun Melsungen AG) for a projected period of 8 weeks. The primary endpoint is the combined change of liver function parameters (total bilirubin, aspartate transaminase and alanine transaminase) from baseline to final visit. Secondary objectives are the further evaluation of the safety and tolerability as well as the efficacy of the ILEs. DISCUSSION: Currently, there are only very few randomized controlled trials (RCTs) investigating the use of ILEs in HPN, and there are very few data at all on the use of n-3 PUFAs. The working hypothesis is that n-3 PUFA-enriched ILE is safe and well-tolerated especially with regard to liver function in patients requiring HPN. The expected outcome is to provide reliable data to support this thesis thanks to a considerable number of CIF patients, consequently to broaden the present evidence on the use of ILEs in HPN. TRIAL REGISTRATION: ClinicalTrials.gov, ID: NCT03282955. Registered on 14 September 2017

Hsp21potentiates antifungal drug tolerance in Candida albicans

Peer reviewedPublisher PD

Effect of a short-term in vitro exposure to the marine toxin domoic acid on viability, tumor necrosis factor-alpha, matrix metalloproteinase-9 and superoxide anion release by rat neonatal microglia

BACKGROUND: The excitatory amino acid domoic acid, a glutamate and kainic acid analog, is the causative agent of amnesic shellfish poisoning in humans. No studies to our knowledge have investigated the potential contribution to short-term neurotoxicity of the brain microglia, a cell type that constitutes circa 10% of the total glial population in the brain. We tested the hypothesis that a short-term in vitro exposure to domoic acid, might lead to the activation of rat neonatal microglia and the concomitant release of the putative neurotoxic mediators tumor necrosis factor-α (TNF-α), matrix metalloproteinases-2 and-9 (MMP-2 and -9) and superoxide anion (O(2)-). RESULTS: In vitro, domoic acid [10 μM-1 mM] was significantly neurotoxic to primary cerebellar granule neurons. Although neonatal rat microglia expressed ionotropic glutamate GluR4 receptors, exposure during 6 hours to domoic acid [10 μM-1 mM] had no significant effect on viability. By four hours, LPS (10 ng/mL) stimulated an increase in TNF-α mRNA and a 2,233 % increase in TNF-α protein In contrast, domoic acid (1 mM) induced a slight rise in TNF-α expression and a 53 % increase (p < 0.01) of immunoreactive TNF-α protein. Furthermore, though less potent than LPS, a 4-hour treatment with domoic acid (1 mM) yielded a 757% (p < 0.01) increase in MMP-9 release, but had no effect on MMP-2. Finally, while PMA (phorbol 12-myristate 13-acetate) stimulated O(2)- generation was elevated in 6 hour LPS-primed microglia, a similar pretreatment with domoic acid (1 mM) did not prime O(2)- release. CONCLUSIONS: To our knowledge this is the first experimental evidence that domoic acid, at in vitro concentrations that are toxic to neuronal cells, can trigger a release of statistically significant amounts of TNF-α and MMP-9 by brain microglia. These observations are of considerable pathophysiological significance because domoic acid activates rat microglia several days after in vivo administration

Physical mapping integrated with syntenic analysis to characterize the gene space of the long arm of wheat chromosome 1A

Background: Bread wheat (Triticum aestivum L.) is one of the most important crops worldwide and its production faces pressing challenges, the solution of which demands genome information. However, the large, highly repetitive hexaploid wheat genome has been considered intractable to standard sequencing approaches. Therefore the International Wheat Genome Sequencing Consortium (IWGSC) proposes to map and sequence the genome on a chromosome-by-chromosome basis. Methodology/Principal Findings: We have constructed a physical map of the long arm of bread wheat chromosome 1A using chromosome-specific BAC libraries by High Information Content Fingerprinting (HICF). Two alternative methods (FPC and LTC) were used to assemble the fingerprints into a high-resolution physical map of the chromosome arm. A total of 365 molecular markers were added to the map, in addition to 1122 putative unique transcripts that were identified by microarray hybridization. The final map consists of 1180 FPC based or 583 LTC based contigs. Conclusions/Significance: The physical map presented here marks an important step forward in mapping of hexaploid bread wheat. The map is orders of magnitude more detailed than previously available maps of this chromosome, and the assignment of over a thousand putative expressed gene sequences to specific map locations will greatly assist future functional studies. This map will be an essential tool for future sequencing of and positional cloning within chromosome 1A