Gas chromatography-mass spectrometry-based metabolite profiling of Salmonella enterica serovar Typhimurium differentiates between biofilm and planktonic phenotypes

The aim of this study was to utilize gas chromatography coupled with mass spectrometry (GC-MS) to compare and identify patterns of biochemical change between Salmonella cells grown in planktonic and biofilm phases and Salmonella biofilms of different ages. Our results showed a clear separation between planktonic and biofilm modes of growth. The majority of metabolites contributing to variance between planktonic and biofilm supernatants were identified as amino acids, including alanine, glutamic acid, glycine, and ornithine. Metabolites contributing to variance in intracellular profiles were identified as succinic acid, putrescine, pyroglutamic acid, and N-acetylglutamic acid. Principal-component analysis revealed no significant differences between the various ages of intracellular profiles, which would otherwise allow differentiation of biofilm cells on the basis of age. A shifting pattern across the score plot was illustrated when analyzing extracellular metabolites sampled from different days of biofilm growth, and amino acids were again identified as the metabolites contributing most to variance. An understanding of biofilm-specific metabolic responses to perturbations, especially antibiotics, can lead to the identification of novel drug targets and potential therapies for combating biofilm-associated diseases. We concluded that under the conditions of this study, GC-MS can be successfully applied as a high-throughput technique for "bottom-up" metabolomic biofilm research

Curcumin and major depression: A randomised, double-blind, placebo-controlled trial investigating the potential of peripheral biomarkers to predict treatment response and antidepressant mechanisms of change

A recent randomised, double-blind, placebo controlled study conducted by our research group, provided partial support for the efficacy of supplementation with a patented curcumin extract (500 mg, twice daily) for 8 weeks in reducing depressive symptoms in people with major depressive disorder. In the present paper, a secondary, exploratory analysis of salivary, urinary and blood biomarkers collected during this study was conducted to identify potential antidepressant mechanisms of action of curcumin. Pre and post-intervention samples were provided by 50 participants diagnosed with major depressive disorder, and the Inventory of Depressive Symptomatology self-rated version (IDS-SR30) was used as the primary depression outcome measure. Compared to placebo, 8 weeks of curcumin supplementation was associated with elevations in urinary thromboxane B2 (p<0.05), and substance P (p<0.001); while placebo supplementation was associated with reductions in aldosterone (p<0.05) and cortisol (p<0.05). Higher baseline plasma endothelin-1 (rs=−0.587; p<0.01) and leptin (rs=−0.470; p<0.05) in curcumin-treated individuals was associated with greater reductions in IDS-SR30 score after 8 weeks of treatment. Our findings demonstrate that curcumin supplementation influences several biomarkers that may be associated with its antidepressant mechanisms of action. Plasma concentrations of leptin and endothelin-1 seem to have particular relevance to treatment outcome. Further investigations using larger samples sizes are required to elucidate these findings, as the multiple statistical comparisons completed in this study increased the risk of type I errors

Meeting halfway: The untapped potential of gender-specific drugs

Personalised medication is one of the ultimate goals of modern medicine although it’s still some way off. But the promise of gender-specific medicines means we may soon be halfway there. In its purest form, personalised medicine would create treatments for each person based on their individual biochemistry and physiology, improving chances of success and reducing potential risks. But while it’s a noble goal, the potential difficulties are obvious. Not only does personalised medicine require a fundamental change to our health-care system, the costs involved in creating individual treatments would be substantial. So it may be decades before we see truly personalised medicines. The halfway point between the current system and personalised medical care are gender-specific medicines, that is, different drugs or different forms of a drug for men and women

Murder-suicide by Tanax® - Pathology, toxicology and veterinary analysis of a forensic case

Poisoning by Tanax® is uncommon as a suicide method, and it is even more unusual for murder-suicides. Tanax® is a veterinary drug used for euthanasia in animals and, as such, poisoning by Tanax® is almost completely limited to veterinary workers. Its active components are embutramide, mebezonium iodide and tetracaine hydrochloride. It acts as a general and local anesthetic, and paralyses skeletal muscles by a curariform-like action. A literature review is provided with focus on embutramide and mebezonium concentrations detected in body fluids and solid organs of patients and victims. A unique case of murder-suicide by Tanax® poisoning is then detailed, leading to the medico-legal diagnosis of a complex suicide method following the murder. This case highlights the heterogeneity of information about lethal concentrations of embutramide and mebezonium in human body fluids and solid organs, the possible emergence of embutramide as a drug of abuse, and the delayed hepatotoxicity induced by dimethylformamide (DMF), contained in Tanax® as an organic solvent

Untargeted metabolomics of neuronal cell culture: A model system for the toxicity testing of insecticide chemical exposure

Toxicity testing is essential for the protection of human health from exposure to toxic environmental chemicals. As traditional toxicity testing is carried out using animal models, mammalian cell culture models are becoming an increasingly attractive alternative to animal testing. Combining the use of mammalian cell culture models with screening-style molecular profiling technologies, such as metabolomics, can uncover previously unknown biochemical bases of toxicity. We have used a mass spectrometry-based untargeted metabolomics approach to characterize for the first time the changes in the metabolome of the B50 cell line, an immortalised rat neuronal cell line, following acute exposure to two known neurotoxic chemicals that are common environmental contaminants; the pyrethroid insecticide permethrin and the organophosphate insecticide malathion. B50 cells were exposed to either the dosing vehicle (methanol) or an acute dose of either permethrin or malathion for 6 and 24 hours. Intracellular metabolites were profiled by gas chromatography-mass spectrometry. Using principal components analysis, we selected the key metabolites whose abundance was altered by chemical exposure. By considering the major fold changes in abundance (>2.0 or <0.5 from control) across these metabolites, we were able to elucidate important cellular events associated with toxic exposure including disrupted energy metabolism and attempted protective mechanisms from excitotoxicity. Our findings illustrate the ability of mammalian cell culture metabolomics to detect finer metabolic effects of acute exposure to known toxic chemicals, and validate the need for further development of this process in the application of trace-level dose and chronic toxicity studies, and toxicity testing of unknown chemicals

Topical prazosin attenuates sensitivity to tactile stimuli in patients with complex regional pain syndrome

Background The sympathetic nervous system may play an important role in certain forms of chronic pain. The main aim of this study was to determine whether functional blockade of α1-adrenoceptors would alter sensitivity to cutaneous stimulation in patients with complex regional pain syndrome (CRPS). Methods and Results In an initial study, high-performance liquid chromatography-mass spectrometry of intradermal interstitial fluid collected from the forearms of three healthy individuals established that the α1-adrenoceptor antagonist prazosin penetrated the skin barrier when mixed in Lipoderm® cream base. Next, we found that application of this cream to the forearm of 10 healthy participants attenuated axon reflex vasodilatation to the iontophoresis of phenylephrine, demonstrating functional blockade of α1-adrenoceptors. Subsequently, effects of the cream on sensitivity to mechanical and thermal stimulation were investigated in 14 healthy participants and 19 patients with CRPS (eight with an apparent adrenergic component of pain). Both in patients and controls, topical application of the prazosin cream increased sensitivity to skin cooling but reduced sensations evoked by gentle brushing. In addition, hyperalgesia to sharp stimulation was lower at the prazosin- than vehicle-treated site in the CRPS-affected limb, and allodynia to brushing was lower at the prazosin-treated than vehicle-treated site in patients with an adrenergic component of pain. Conclusions Prazosin cream inhibited adrenergic axon reflex vasodilatation in healthy volunteers, and also inhibited dynamic allodynia and punctate hyperalgesia in the CRPS-affected limb of some patients. Further studies are required to assess the potential benefits of topically applied prazosin for CRPS

Role of neuregulin-1β in dexamethasone-enhanced surfactant synthesis in fetal type II cells

It is well established that glucocorticoids elevate the production of fibroblast-pneumocyte factor (FPF), which induces type II cells to synthesize surfactant phospholipids. FPF, however, has not been identified and it is not clear whether it is a single factor or a complex mixture of factors. In this study it has been shown that, when lung fibroblasts are exposed to dexamethasone, the concentration of neuregulin-1β (NRG1β) in conditioned medium is elevated 2-fold (P < 0.05), even though NRG1β gene expression is unaffected. This, together with the finding that exposure of type II cells to NRG1β directly stimulates by 3-fold the rate of phospholipid synthesis (P < 0.05), suggests that NRG1β is a component of FPF that promotes lung development

Role of neuregulin-1β in dexamethasone-enhanced surfactant phospholipid synthesis in rat fetal type ii pneumocytes

Surfactant production is known to involve a cellular communication between lung fibroblasts and the type II pneumocytes. Glucocorticoids induce the production of a peptide by lung fibroblasts, fibroblast-pneumocyte factor (FPF), which sequentially acts on type II cells to enhance the synthesis of surfactant phospholipid. Our findings show that fibroblast-conditioned medium (FCM), generated in the presence of dexamethasone, not only enhanced surfactant phospholipid synthesis in type II cells but also contained an elevated concentration of neuregulin-1β (NRG1β). Even though it has been earlier proposed that leptin has many of the characteristics of FPF, recent research has revealed that NRG1β also has many similar attributes. In the current study, exposure of the type II cells to a commercially available form of NRG1β (heregulin-1β) directly stimulated by more than three-fold the rate of phospholipid synthesis (p <0.05). Although similar in magnitude, the effect of heregulin-1β appeared to require a longer time of exposure to that reported for leptin. There was no increase in the gene expression of NRG1β when lung fibroblasts were exposed to dexamethasone, irrespective of the concentration of dexamethasone used, or the time of contact of the cells to the steroid. Thus the glucocorticoid-induced increase in the level of NRG1β in FCM was not the result of enhanced expression of the NRG1β gene. The inability of dexamethasone to induce a significant increase in NRG1β gene expression in lung fibroblasts suggests that the elevated concentration of NRG1β might be the result of enhanced cleavage of the membrane-bound neuregulin precursor. In summary, these findings not only support but significantly extend the concept previously promoted that NRG1β plays an essential role in the differentiation and maturation of the lung in the later stages of gestation. Moreover, together these studies suggest that FPF may be a complex mixture of agents capable of motivating surfactant synthesis

A review of peripheral biomarkers in major depression: The potential of inflammatory and oxidative stress biomarkers

Biomarkers are regularly used in medicine to provide objective indicators of normal biological processes, pathogenic processes or pharmacological responses to therapeutic interventions, and have proved invaluable in expanding our understanding and treatment of medical diseases. In the field of psychiatry, assessment and treatment has, however, primarily relied on patient interviews and questionnaires for diagnostic and treatment purposes. Biomarkers in psychiatry present a promising addition to advance the diagnosis, treatment and prevention of psychiatric diseases. This review provides a summary on the potential of peripheral biomarkers in major depression with a specific emphasis on those related to inflammatory/immune and oxidative stress/antioxidant defences. The complexities associated with biomarker assessment are reviewed specifically around their collection, analysis and interpretation. Focus is placed on the potential of peripheral biomarkers to aid diagnosis, predict treatment response, enhance treatment-matching, and prevent the onset or relapse of major depression

Branched-chain amino acid supplementation improves cycling performance in untrained cyclists

Objectives To investigate the effects of acute branched-chain amino acid (BCAA) supplementation on cycling performance and neuromuscular fatigue during a prolonged, self-paced cycling time-trial. Design Randomised double-blind counterbalanced crossover. Methods Eighteen recreationally active men (mean ± SD; age: 24.7 ± 4.8 years old; body-weight, BW: 67.1 ± 6.1 kg; height: 171.7 ± 4.9 cm) performed a cycling time-trial on an electromagnetically-braked cycle ergometer. Participants were instructed to complete the individualised total work in the shortest time possible, while ingesting either BCAAs (pre-exercise: 0.084 g kg−1 BW; during exercise: 0.056 g kg−1 h−1) or a non-caloric placebo solution. Rating of perceived exertion, power, cadence and heart rate were recorded throughout, while maximal voluntary contraction, muscle voluntary activation level and electrically evoked torque using single and doublet stimulations were assessed at baseline, immediately post-exercise and 20-min post-exercise. Results Supplementation with BCAA reduced (287.9 ± 549.7 s; p = 0.04) time-to-completion and ratings of perceived exertion (p ≤ 0.01), while concomitantly increasing heart rate (p = 0.02). There were no between-group differences (BCAA vs placebo) in any of the neuromuscular parameters, but significant decreases (All p ≤ 0.01) in maximal voluntary contraction, muscle voluntary activation level and electrically evoked torque (single and doublet stimulations) were recorded immediately following the trial, and these did not recover to pre-exercise values by the 20 min recovery time-point. Conclusions Compared to a non-caloric placebo, acute BCAA supplementation significantly improved performance in cycling time-trial among recreationally active individuals without any notable changes in either central or peripheral factors. This improved performance with acute BCAA supplementation was associated with a reduced rating of perceived exertion