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Surfactin is a lipopeptide of the biosurfactant class, most commonly produced by Bacillus subtilis, a Gram-positive bacterium. The chemical structure of surfactin is composed of peptide bound to carboxyl groups and hydrocarboxyl of long chain fatty acids. Surfactin production may be influenced by the strain, inoculum and age of the microorganism, as well as physical factors such as temperature, pH, agitation speed, aeration degree, foam formation and dissolved oxygen concentration and nutritional factors, such as carbon, nitrogen and trace elements in the culture media. The potential areas of application of this biosurfactant are therapeutic and environmental. This work aims to address structural aspects, factors involved in production by microorganisms and the application areas of surfactin. [ABSTRACT FROM AUTHOR]

The article discusses a study entitled "Flame spread through porous fuels," by P.J. Pagni and T.G. Peterson.

A computational procedure for predicting the buoyant plume above a line fire in a cross wind is reported. The present model takes into account the interaction between the plume and the surrounding flow by solving the two-dimensional equations for the conservation of mass, momentum, and energy. Fields of velocity and temperature are predicted along with plume trajectory and width for different wind speeds. Thismodel can be used to evaluate the impact of a wildland fire upon vegetation such as crown scorch, burning brands trajectory, and smoke orash dispersal. [ABSTRACT FROM AUTHOR]

Background: The precision and accuracy of mass spectrometry (MS) made it a fundamental tool in anti-doping analysis. High-resolution (HR) mass spectrometers significantly improved compound identification. This study systematically analyzes data from an athlete (Subject 1) who tested positive for meldonium and compares it with data from a healthy volunteer (Subject 2) to examine the correctness of the doping verdict., Case Presentation: The documentation related to Subject 1 was thoroughly processed and analyzed. A study involving a volunteer (Subject 2) replicated Subject 1 regimen and urine sample collection for data alignment with anti-doping results, with Subject 2 reporting not using meldonium. The anti-doping agency's analysis of Subject 1 showed the presence of meldonium at a concentration close to the established cut-off level. However, a closer examination revealed that one specific ion, crucial for meldonium identification, was absent from the mass spectra. Analyzing Subject 2 data, using the same methodology, the absence of the specific ion was confirmed, even though the volunteer did not consume meldonium. The European directive and the method that was validated and cited by the anti-doping agency identified meldonium on at least four specific ions, whereas the anti-doping analysis used only three ions. This discrepancy compromises the specificity of meldonium identification., Conclusions: To enhance the analytical methodology, two strategic interventions are suggested: adjusting the meldonium cut-off value and expanding the analysis to include meldonium metabolites. By addressing these avenues, the precision of meldonium detection and doping verdicts can be improved. In conclusion, this study challenges the anti-doping agency's verdict and prompts a reevaluation of meldonium detection methodologies in anti-doping measures.

Water holds great relevance in various biological and biochemical systems. Water behaves as an excellent solvent, a reactant, a product and a catalyst of the reaction. The organisation of the water molecules, synergised by hydrogen bonds, builds up the structure of the water clusters. These water clusters significantly influence biological functions. To study the domain of water clusters using Ion mobility mass spectrometry with surface activated chemical ionisation. The experimental analysis was aimed to determine the water behaviour in terms of cluster formation before and after the application of a physical effect, namely low-frequency irradiation. A sanist platform-based spectrometer, manufactured by ISB srl with SACI version for protein analysis, was used as the equipment. Furthermore, for samples, we used pure de-ionised water, a part of which was used virgin, and another part was irradiated. Ion-mobility mass spectrometry (IM-MS) procedure was adopted as the experimental method. An electromagnetic frequency fields generator was used to subject the test samples to electromagnetic radiations between 7 Hz to 80 Hz. The presence of neutral water species was confirmed in the water samples. For the same m/z, water ion clusters in the untreated water were found to have a much higher intensity than the electromagnetically treated water. The presence of a water cluster near the (M+H) + in electromagnetically treated dilute arginine solution was also confirmed. It is possible to detect water ion clusters by using Ion mobility mass spectrometry and SACI with low surface potential (47 V). The water cluster formation and its characteristics were found to be different in the treated and non-treated water. The electromagnetic radiations of low frequency seem to affect the hydrogen bonds of the water molecules., (©2022 Pacini Editore SRL, Pisa, Italy.)

In this work, the isolation step in the linear ion trap was performed using different "q values" conditions at a low collision-induced dissociation (CID) energy leading to the parent ion resolution improvements, reasonably due to better ion energy distribution. According to the results, we obtained a greater resolution and mass accuracy operating in both traditional electrospray and low voltage ionization near the q value = 0.778 and with a CID energy of 10%. This effect was evaluated with low-molecular-mass compounds (skatole and arginine). The proposed optimization yielded a superior instrument performance without adding technological complexity to mass spectrometry analyses., (© 2022 John Wiley & Sons Ltd.)

Rationale: Advances in metabolomics, together with consolidated genetic approaches, have opened the way for investigating the health of patients using a large number of molecules simultaneously, thus providing firm scientific evidence for personalized medicine and consequent interventions. Metabolomics is an ideal approach for investigating specific biochemical alterations occurring in rare clinical situations, such as those caused by rare associations between comorbidities and immunosuppression., Methods: Metabolomic database matching enables clear identification of molecular factors associated with a metabolic disorder and can provide a rationale for elaborating personalized therapeutic protocols. Mass spectrometry (MS) forms the basis of metabolomics and uses mass-to-charge ratios for metabolite identification. Here, we used an MS-based approach to diagnose and develop treatment options in the clinical case of a patient afflicted with a rare disease further complicated by immunosuppression. The patient's data were analyzed using proprietary databases, and a personalized and efficient therapeutic protocol was consequently elaborated., Results: The patient exhibited significant alterations in homocysteine:methionine and homocysteine:thiodiglycol acid plasma concentration ratios, and these were associated with low immune system function. This led to cysteine concentration deficiency causing extreme oxidative stress. Plasmatic thioglycolic acid concentrations were initially altered and were used for therapeutic follow-up and to evaluate cysteine levels., Conclusions: An MS-based pharmacometabolomics approach was used to define a personalized protocol in a clinical case of rare peritoneal carcinosis with confounding immunosuppression. This personalized protocol reduced both oxidative stress and resistance to antibiotics and antiviral drugs., (© 2020 John Wiley & Sons, Ltd.)

A "heart-cut" two-dimensional achiral-chiral liquid chromatography triple-quadrupole mass spectrometry method (LC-LC-MS/MS) was developed and coupled to in vivo cerebral microdialysis to evaluate the brain response to the chiral compound (±)-7-chloro-5-(3-furanyl)-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine-1,1-dioxide ((±)-1), a potent positive allosteric modulator (PAM) of AMPA receptor. The method was successfully employed to evaluate also its stereoselective metabolism and in vitro biological activity. In particular, the LC achiral method developed, employs a pentafluorinated silica based column (Discovery HS-F5) to separate dopamine, acetylcholine, serotonin, (±)-1 and its two hepatic metabolites. In the "heart-cut" two-dimension achiral-chiral configuration, (±)-1 and (±)-1-d4 eluted from the achiral column (1st dimension), were transferred to a polysaccharide-based chiral column (2nd dimension, Chiralcel OD-RH) by using an automatic six-port valve. Single enantiomers of (±)-1 were separated and detected using electrospray positive ionization mode and quantified in selected reaction monitoring mode. The method was validated and showed good performance in terms of linearity, accuracy and precision. The new method employed showed several possible applications in the evaluation of: (a) brain response to neuroactive compounds by measuring variations in the brain extracellular levels of selected neurotransmitters and other biomarkers; (b) blood brain barrier penetration of drug candidates by measuring the free concentration of the drug in selected brain areas; (c) the presence of drug metabolites in the brain extracellular fluid that could prove very useful during drug discovery; (d) a possible stereoselective metabolization or blood brain barrier stereoselective crossing of chiral drugs. Finally, compared to the methods reported in the literature, this technique avoids the necessity of euthanizing an animal at each time point to measure drug concentration in whole brain tissue and provides continuous monitoring of extracellular concentrations of single chiral drug enantiomers along with its metabolites in specific brain regions at each selected time point for a desired period by using a single animal., (Copyright © 2016 Elsevier B.V. All rights reserved.)

An iridium-iridium oxide electrode for in vivo pH measurement of the distal oesophagus is described. It is small and flexible so it is well accepted by patients for long-term pH monitoring. The electrode also offers the possibility of including another electrode and/or a pressure sensor for simultaneous detection of two or more parameters--gastric pH or oesophageal pressure for example. A clinical study was performed on 15 healthy volunteers and the results were checked on a DGC Nova 4/S computer, showing less than 0.005% of tension in mV out of the established range in a period of 24 h pH monitoring. The volunteers' results were compared with the normal values obtained by DeMeester using a glass electrode on a similar, healthy group of American patients and no significant differences were observed. Owing to its small size, reliability, fast response to pH changes, durability and its easy storage, the Ir/IrO2 electrode is ideal for long-term pH monitoring of the upper gastro-intestinal tract.