Synthesis of distinctly different sets of antimicrobial activities by elicited plant cell suspension cultures

The aim of this study was to evaluate the potential of plant suspension cultures for the production of antimicrobial activities. The extracellular, intracellular and cell wall bound fractions of 16 heterotrophic, photoautotrophic and photomixotrophic plant cell suspension cultures each treated with nine different elicitors were tested for the elicitor dependent production of antimicrobial activities. Distinctly different patterns of bioactivities directed against a panel of human isolates including Gram-positive (Bacillus subtilis, Staphylococcus aureus) and Gram-negative (Escherichia coli, Pseudomonas aeruginosa) bacteria as well as fungi (Candida maltosa) were identified for all except the two autotrophic cell cultures. The intracellular fractions of elicited cell cultures were more active than extracellular fractions while cell wall bound fractions showed almost no activities. The intracellular fraction of heterotrophic Lavendula angustifolia cells elicited with a preparation of Pseudomonas syringae was the most active fraction against Candida maltosa. The intracellular fraction of photomixotrophic Arabidopsis thaliana cells elicited with salicylic acid was active against all test isolates. An antimicrobial protein could be identified and partially purified from this culture. Our findings suggest that elicited plant cell cultures may present a new promising alternative source of antimicrobial proteins.     

Paraoxonase 1 protects macrophages from atherogenicity of a specific triglyceride isolated from human carotid lesion

Human atherosclerotic lesions contain oxidized lipids that facilitate further oxidation of macrophages, LDLs, and oxidative stress (OS)-sensitive markers and inhibit the antiatherogenic enzyme paraoxonase 1 (PON1). Our aim was to isolate and identify the oxidizing agent in a human atherosclerotic lesion lipid extract (LLE) and to explore the mechanisms of oxidation and of PON1's effect on the oxidizing agent. Of the five main fractions separated from the LLE, only fraction 2 (F2) promoted macrophage reactive oxygen species (ROS) production via a mechanism requiring mitochondrial involvement, whereas the NADPH oxidase system was not involved. Incubation of F2 with PON1 abridged the former's peroxide value and reduced its capacity to oxidize OS markers. The active agent was a triglyceride composed of palmitic, oleic, and linoleic acids, with 0.3% of its linoleic moiety in oxidized form. Incubation of either F2 or an identical synthetic triglyceride with PON1 reduced their ability to oxidize macrophages, without affecting cellular accumulation of triglycerides. We conclude that macrophage ROS production by LLE occurs in the presence of a specific triglyceride and requires mitochondrial involvement. Lipid peroxide in the triglyceride can also facilitate lipid autoxidation. Both atherogenic pathways are suppressed by PON1, which acts as an antiatherogenic element.     

The BD BACTEC FX blood culture system with the gentlemacs dissociator is suitable for sterility testing of heart valve and vascular allografts—A validation study

Cell and Tissue Banking - To present our validation study of the BD BACTEC FX blood culture system for sterility testing of cardiovascular tissues aimed for human application. For operational...     

Docosahexaenoic acid (DHA) incorporation into the brain from plasma, as an in vivo biomarker of brain DHA metabolism and neurotransmission

Docosahexaenoic acid (DHA) is critical for maintaining normal brain structure and function, and is considered neuroprotective. Its brain concentration depends on dietary DHA content and hepatic conversion from its dietary derived n-3 precursor, α-linolenic acid (α-LNA). We have developed an in vivo method in rats using quantitative autoradiography and intravenously injected radiolabeled DHA to image net incorporation into the brain of unesterified plasma DHA, and showed with this method that the incorporation rate of DHA equals the rate of brain metabolic DHA consumption. The method has been extended for use in humans with positron emission tomography (PET). Furthermore, imaging in unanesthetized rats using DHA incorporation as a biomarker in response to acute N-methyl-D-aspartate administration confirms that regional DHA signaling is independent of extracellular calcium, and likely mediated by a calcium-independent phospholipase A(2) (iPLA(2)). Studies in mice in which iPLA(2)-VIA (β) was knocked out confirmed that this enzyme is critical for baseline and muscarinic cholinergic signaling involving DHA. Thus, quantitative imaging of DHA incorporation from plasma into brain can be used as an in vivo biomarker of brain DHA metabolism and neurotransmission.     

The ubiquitin-selective segregase VCP/p97 orchestrates the response to DNA double-strand breaks

Unrepaired DNA double-strand breaks (DSBs) cause genetic instability that leads to malignant transformation or cell death. Cells respond to DSBs with the ordered recruitment of signalling and repair proteins to the site of lesion. Protein modification with ubiquitin is crucial for the signalling cascade, but how ubiquitylation coordinates the dynamic assembly of these complexes is poorly understood. Here, we show that the human ubiquitin-selective protein segregase p97 (also known as VCP; valosin-containing protein) cooperates with the ubiquitin ligase RNF8 to orchestrate assembly of signalling complexes and efficient DSB repair after exposure to ionizing radiation. p97 is recruited to DNA lesions by its ubiquitin adaptor UFD1-NPL4 and Lys-48-linked ubiquitin (K48-Ub) chains, whose formation is regulated by RNF8. p97 subsequently removes K48-Ub conjugates from sites of DNA damage to orchestrate proper association of 53BP1, BRCA1 and RAD51, three factors critical for DNA repair and genome surveillance mechanisms. Impairment of p97 activity decreases the level of DSB repair and cell survival after exposure to ionizing radiation. These findings identify the p97-UFD1-NPL4 complex as an essential factor in ubiquitin-governed DNA-damage response, highlighting its importance in guarding genome stability.     

Central and peripheral venous lines-associated blood stream infections in the critically ill surgical patients

ABSTRACT: Critically ill surgical patients are always at increased risk of actual or potentially life-threatening health complications. Central/peripheral venous lines form a key part of their care. We review the current evidence on incidence of central and peripheral venous catheter-related bloodstream infections in critically ill surgical patients, and outline pathways for prevention and intervention. An extensive systematic electronic search was carried out on the relevant databases. Articles were considered suitable for inclusion if they investigated catheter colonisation and catheter-related bloodstream infection. Two independent reviewers were engaged in selecting appropriate articles in line with the above protocol. Our search protocol retrieved 8 articles published from 1999 to 2011. Outcomes on CVC colonisation and infections were investigated in six studies; four of which were prospective cohort studies, one prospective longitudinal study and one retrospective cohort study. Outcomes relating only to PICCs were reported in one prospective randomised trial. We identified only one study that compared CVC- and PICC-related complications in surgical intensive care units. Although our search protocol may not have yielded an exhaustive list we have identified a key deficiency in the literature, namely a paucity of studies investigating the incidence of CVC- and PICC-related bloodstream infection in exclusively critically ill surgical populations. In summary, the diverse definitions for the diagnosis of central and peripheral venous catheter-related bloodstream infections along with the vastly different sample size and extremely small PICC population size has, predictably, yielded inconsistent findings. Our current understanding is still limited; the studies we have identified do point us towards some tentative understanding that the CVC/PICC performance remains inconclusive.     

L-citrulline supplementation reverses the impaired airway relaxation in neonatal rats exposed to hyperoxia

Background

Hyperoxia is shown to impair airway relaxation via limiting L-arginine bioavailability to nitric oxide synthase (NOS) and reducing NO production as a consequence. L-arginine can also be synthesized by L-citrulline recycling. The role of L-citrulline supplementation was investigated in the reversing of hyperoxia-induced impaired relaxation of rat tracheal smooth muscle (TSM).

Methods

Electrical field stimulation (EFS, 2–20 V)-induced relaxation was measured under in vitro conditions in preconstricted tracheal preparations obtained from 12 day old rat pups exposed to room air or hyperoxia (>95% oxygen) for 7 days supplemented with L-citrulline or saline (in vitro or in vivo). The role of the L-citrulline/L-arginine cycle under basal conditions was studied by incubation of preparations in the presence of argininosuccinate synthase (ASS) inhibitor [α-methyl-D, L-aspartate, 1 mM] or argininosuccinate lyase inhibitor (ASL) succinate (1 mM) and/or NOS inhibitor [N^ω-nitro-L-arginine methyl ester; 100 μM] with respect to the presence or absence of L-citrulline (2 mM).

Results

Hyperoxia impaired the EFS-induced relaxation of TSM as compared to room air control (p < 0.001; 0.5 ± 0.1% at 2 V to 50.6 ± 5.7% at 20 V in hyperoxic group: 0.7 ± 0.2 at 2 V to 80.0 ± 5.6% at 20 V in room air group). Inhibition of ASS or ASL, and L-citrulline supplementation did not affect relaxation responses under basal conditions. However, inhibition of NOS significantly reduced relaxation responses (p < 0.001), which were restored to control level by L-citrulline. L-citrulline supplementation in vivo and in vitro also reversed the hyperoxia-impaired relaxation. The differences were significant (p <0.001; 0.8 ± 0.3% at 2 V to 47.1 ± 4.1% at 20 V without L-citrulline; 0.9 ± 0.3% at 2 V to 68.2 ± 4.8% at 20 V with L-citrulline). Inhibition of ASS or ASL prevented this effect of L-citrulline.

Conclusion

The results indicate the presence of an L-citrulline/L-arginine cycle in the airways of rat pups. L-citrulline recycling does not play a major role under basal conditions in airways, but it has an important role under conditions of substrate limitations to NOS as a source of L-arginine, and L-citrulline supplementation reverses the impaired relaxation of airways under hyperoxic conditions.