Browsing by Subject "ACID"

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  • Niemelä, Tytti M.; Tulamo, Riitta-Mari; Hielm-Björkman, Anna K. (2016)
    Background: Intra-articular inflammation resulting in lameness is a common health problem in horses. Exogenous intra-articular hyaluronic acid has been shown to provide an analgesic effect and reduce pain in equine and human osteoarthritis. High molecular weight non-animal stabilized hyaluronic acid (NASHA) has gained popularity in the treatment of human arthritic conditions due to its long-acting pain-relieving effects. The aim of this study was to compare the response to treatment of lameness localized in the equine metacarpophalangeal joint injected with non-animal stabilized hyaluronic acid (NASHA) and placebo (saline). Twenty-seven clinically lame horses with a positive response to diagnostic intra-articular anaesthesia of the metacarpophalangeal joint and with no, or at most mild, radiographic changes in this joint were included in the study. Horses in the treatment group (n = 14) received 3 mL of a NASHA product intra-articularly, and those in the placebo group (n = 13) received an equivalent volume of sterile 0.9 % saline solution. Results: The change in the lameness score did not significantly differ between NASHA and placebo groups (P = 0.94). Scores in the flexion test improved more in the NASHA group compared with placebo (P = 0.01). The changes in effusion and pain in flexion were similar (P = 0.94 and P = 0.27, respectively) when NASHA and placebo groups were compared. A telephone interview follow-up of the owners three months post-treatment revealed that 14 of the 21 horses (67 %) were able to perform at their previous level of exercise. Conclusions: In the present study, a single IA NASHA injection was not better than a single saline injection for reducing lameness in horses with synovitis or mild osteoarthritis. However, the results of this study indicate that IA NASHA may have some beneficial effects in modifying mild clinical signs but more research is needed to evaluate whether the positive effect documented ie. reduced response in the flexion test is a true treatment effect.
  • Benetto Tiz, Davide; Skok, Žiga; Durcik, Martina; Tomašič, Tihomir; Peterlin Mašič, Lucija; Ilaš, Janez; Draskovits, Gábor; Révész, Tamás; Nyerges, Ákos; Pál, Csaba; Cruz, Cristina D.; Tammela, Päivi Sirpa Marjaana; Žigon, Dušan; Kikelj, Danijel; Zidar, Nace (2019)
    ATP competitive inhibitors of DNA gyrase and topoisomerase IV have great therapeutic potential, but none of the described synthetic compounds has so far reached the market. To optimise the activities and physicochemical properties of our previously reported N-phenylpyrrolamide inhibitors, we have synthesized an improved, chemically variegated selection of compounds and evaluated them against DNA gyrase and topoisomerase IV enzymes, and against selected Gram-positive and Gram-negative bacteria. The most potent compound displayed IC50 values of 6.9 nM against Escherichia coli DNA gyrase and 960 nM against Staphylococcus aureus topoisomerase IV. Several compounds displayed minimum inhibitory concentrations (MICs) against Gram-positive strains in the 1-50 mu M range, one of which inhibited the growth of Enterococcus faecalis, Enterococcus faecium, S. aureus and Streptococcus pyogenes with MIC values of 1.56 mu M, 1.56 mu M, 0.78 mu M and 0.72 mu M, respectively. This compound has been investigated further on methicillin-resistant S. aureus (MRSA) and on ciprofloxacin non-susceptible and extremely drug resistant strain of S. aureus (MRSA VISA). It exhibited the MIC value of 2.5 mu M on both strains, and MIC value of 32 mu M against MRSA in the presence of inactivated human blood serum. Further studies are needed to confirm its mode of action. (C) 2019 Elsevier Masson SAS. All rights reserved.
  • Trojnar, Eszter; Jozsi, Mihaly; Uray, Katalin; Csuka, Dorottya; Szilagyi, Agnes; Milosevic, Danko; Stojanovic, Vesna D.; Spasojevic, Brankica; Rusai, Krisztina; Mueller, Thomas; Arbeiter, Klaus; Kelen, Kata; Szabo, Attila J.; Reusz, Gyorgy S.; Hyvarinen, Satu; Jokiranta, T. Sakari; Prohaszka, Zoltan (2017)
    Introduction: In autoimmune atypical hemolytic uremic syndrome (aHUS), the complement regulator factor H (FH) is blocked by FH autoantibodies, while 90% of the patients carry a homozygous deletion of its homolog complement FH-related protein 1 (CFHR1). The functional consequence of FH-blockade is widely established; however, the molecular basis of autoantibody binding and the role of CFHR1 deficiency in disease pathogenesis are still unknown. We performed epitope mapping of FH to provide structural insight in the autoantibody recruitment on FH and potentially CFHR1. Methods: Eight anti-FH positive aHUS patients were enrolled in this study. With overlapping synthetic FH and CFHR1 peptides, we located the amino acids (aa) involved in binding of acute and convalescence stage autoantibodies. We confirmed the location of the mapped epitopes using recombinant FH domains 19-20 that carried single-aa substitutions at the suspected antibody binding sites in three of our patients. Location of the linear epitopes and the introduced point mutations was visualized using crystal structures of the corresponding domains of FH and CFHR1. Results: We identified three linear epitopes on FH (aa1157-1171; aa1177-1191; and aa1207-1226) and one on CFHR1 (aa276-290) that are recognized both in the acute and convalescence stages of aHUS. We observed a similar extent of autoantibody binding to the aHUS-specific epitope aa1177-1191 on FH and aa276-290 on CFHR1, despite seven of our patients being deficient for CFHR1. Epitope mapping with the domain constructs validated the location of the linear epitopes on FH with a distinct autoantibody binding motif within aa1183-1198 in line with published observations. Summary: According to the results, the linear epitopes we identified are located close to each other on the crystal structure of FH domains 19-20. This tertiary configuration contains the amino acids reported to be involved in C3b and sialic acid binding on the regulator, which may explain the functional deficiency of FH in the presence of auto antibodies. The data we provide identify the exact structures involved in autoantibody recruitment on FH and confirm the presence of an autoantibody binding epitope on CFHR1.
  • Pathak, Lakshmi; Singh, Vineeta; Niwas, Ram; Osama, Khwaja; Khan, Saif; Haque, Shafiul; Tripathi, C. K. M.; Mishra, B. N. (2015)
    Cholesterol oxidase (COD) is a bi-functional FAD-containing oxidoreductase which catalyzes the oxidation of cholesterol into 4-cholesten-3-one. The wider biological functions and clinical applications of COD have urged the screening, isolation and characterization of newer microbes from diverse habitats as a source of COD and optimization and over-production of COD for various uses. The practicability of statistical/artificial intelligence techniques, such as response surface methodology (RSM), artificial neural network (ANN) and genetic algorithm (GA) have been tested to optimize the medium composition for the production of COD from novel strain Streptomyces sp. NCIM5500. All experiments were performed according to the five factor central composite design (CCD) and the generated data was analysed using RSM and ANN. GA was employed to optimize the models generated by RSM and ANN. Based upon the predicted COD concentration, the model developed with ANN was found to be superior to the model developed with RSM. The RSM-GA approach predicted maximum of 6.283 U/mL COD production, whereas the ANN-GA approach predicted a maximum of 9.93 U/mL COD concentration. The optimum concentrations of the medium variables predicted through ANN-GA approach were: 1.431 g/50 mL soybean, 1.389 g/50 mL maltose, 0.029 g/50 mL MgSO4, 0.45 g/50 mL NaCl and 2.235 ml/50 mL glycerol. The experimental COD concentration was concurrent with the GA predicted yield and led to 9.75 U/mL COD production, which was nearly two times higher than the yield (4.2 U/mL) obtained with the un-optimized medium. This is the very first time we are reporting the statistical versus artificial intelligence based modeling and optimization of COD production by Streptomyces sp. NCIM 5500.
  • Rantalainen, V.; Lahti, J.; Henriksson, M.; Kajantie, E.; Mikkonen, M.; Eriksson, J. G.; Räikkönen, Katri (2018)
    Background. Being breastfed in infancy has been shown to benefit neurodevelopment. However, whether the benefits persist to old age remains unclear. Methods. We examined the associations between breastfeeding and its duration on cognitive ability in young adulthood and old age, and on aging-related cognitive change over five decades. In total, 931 men from the Helsinki Birth Cohort Study born in 1934-1944 in Finland took the Finnish Defence Forces Basic Intellectual Ability Test (total and verbal, arithmetic and visuospatial subtest scores) twice, at ages 20.2 and 67.9 years, and had data on breastfeeding (yes v. no) and its duration ('never breastfed', 'up to 3', '3 to 6' and 6 or more months'). Linear and mixed model regressions tested the associations. Results. At 20.2 years, breastfed men had higher cognitive ability total and visuospatial subtest scores [mean differences (MDs) ranged between 3.0-3.9, p values <0.013], and its longer duration predicted higher cognitive ability total and arithmetic and visuospatial subtest scores (MDs ranged between 3.0 and 4.8, p values <0.039). At 67.9 years, breastfed men had higher total cognitive ability and all subtest scores (MDs ranged between 2.6 and 3.4, p values <0.044) and its longer duration predicted all cognitive ability scores (MDs ranged between 3.1 and 4.7, p values <0.050). Verbal subtest scores decreased over five decades in men who were never breastfed or were breastfed for 3 months or less, and increased in those breastfed for longer than 3 months. Conclusions. Neurodevelopmental advantages of breastfeeding and its longer duration persist into old age, and longer duration of breastfeeding may benefit aging-related change, particularly in verbal reasoning ability.
  • Lakanmaa, Riitta-Liisa; Suominen, Tarja; Ritmala-Castren, Marita; Vahlberg, Tero; Leino-Kilpi, Helena (2015)
    Critical care patients benefit from the attention of nursing personnel with a high competence level. The aim of the study was to describe and evaluate the self-assessed basic competence of intensive care unit nurses and related factors. A cross-sectional survey design was used. A basic competence scale (Intensive and Critical Care Nursing Competence Scale version 1, Likert scale 1-5, 1 = poor and 5 = excellent) was employed among Finnish intensive care unit nurses (n = 431). Intensive care unit nurses' self-assessed basic competence was good (mean 4.19, SD 0.40). The attitude and value base of basic competence was excellent whereas experience base was the poorest compared to the knowledge base and skill base of intensive and critical care nursing. The strongest factor explaining nurses' basic competence was their experience of autonomy in nursing care (F value 60.85, beta 0.11, SE 0.01, and P
  • Häkkinen, Suvi T.; Nygren, Heli; Maiorova, Natalia; Haavikko, Raisa; Alakurtti, Sami; Yli-Kauhaluoma, Jari; Rischer, Heiko; Oksman-Caldentey, Kirsi-Marja (2018)
    In this study, three semisynthetic betulonic acid-based compounds, 20(29)-dihydrolup-2-en[2,3- d ]isoxazol-28-oic acid, 1-betulonoylpyrrolidine, and lupa-2,20(29)-dieno[2,3- b ]pyrazin-28-oic acid, were studied in biotransformation experiments using Nicotiana tabacum and Catharanthus roseus cell suspension cultures. Biotransformation was performed using cyclodextrin to aid dissolving poorly water-soluble substrates. Several new derivatives were found, consisting of oxidized and glycosylated (pentose- and hexose-conjugated) products.
  • Kolsi, Laura E.; Yli-Kauhaluoma, Jari; Moreira, Vânia M. (2018)
    Bi(OTf)(3)center dot xH(2)O is a powerful catalyst for the dehydration of tertiary alcohols into alkenes in apolar solvents. The reaction proceeds smoothly and selectively, with amounts as low as 0.01 mol % catalyst, in yields up to 93%. Moreover, in polar solvents, Bi(OTf)(3)center dot xOH(2)O (0.1-1 mol %) selectively catalyzes the dimerization of the alcohols instead, forming new C-C bonds, in yields up to 96%. This mild, efficient, economic, and eco-friendly method is applicable across different chemical classes and amenable to several functional groups.
  • Kluger, Yoram; Ben Ishay, Ofir; Sartelli, Massimo; Katz, Amit; Ansaloni, Luca; Gomez, Carlos Augusto; Biffl, Walter; Catena, Fausto; Fraga, Gustavo P.; Di Saverio, Salomone; Goran, Augustin; Ghnnam, Wagih; Kashuk, Jeffry; Leppaniemi, Ari; Marwah, Sanjay; Moore, Ernest E.; Bala, Miklosh; Massalou, Damien; Mircea, Chirica; Bonavina, Luigi (2015)
    Caustic material ingestion injuries (CMI) are uncommon. Only 5,000 cases are reported in the United States each year and most acute care healthcare facilities admit only a few cases annually. Accordingly, no single institution can claim extensive experience, and management protocols are most probably based on either expert opinion or literature reports. In this study, we will attempt to review opinions and practices of representatives of the board members of the World Society of Emergency Surgery and compare them to the current literature.
  • Oksuz, Tugba; Tacer-Caba, Zeynep; Nilufer-Erdil, Dilara; Boyacioglu, Dilek (2019)
    In this study, it is aimed to understand the changes in sour cherry phytochemicals when their co-digestions are simulated in dairy model systems comprising skim milk, non-fat-yoghurt, probiotic yoghurt or cream. These co-digestions were analyzed for their total phenolic and anthocyanin contents, total antioxidant activity (TAA) in addition to phenolic and anthocyanin profiles, individually. Sour cherry phenolics were stable during gastric conditions (120%); 54% lost in pancreatic digestion and being available (59%) in serum available fraction (IN). Anthocyanins were lost both in gastric (30%) and pancreatic digestions (16%), being only little available (0.6%) in IN. Soymilk had inhibitory effects on TAA. Dairy food matrix components evaluated were found to have distinct effects on the measured bioavailability of individual sour cherry phenolics. This study might aid both consumers and industry on selecting the food matrices to aiding increase in bioavailability.
  • Anton, Dea; Bender, Ingrid; Kaart, Tanel; Roasto, Mati; Heinonen, Marina; Luik, Anne; Puessa, Tonu (2017)
    Polyphenols of fruits and vegetables form an important part of human dietary compounds. Relatively little is known about accumulation of phenolics during fruits ripening process. The goal of this work was to study the changes in antioxidant activity and in content of 30 polyphenols during ripening of tomato fruits. Five organically and conventionally grown tomato cultivars were investigated at three different ripening stages. Phenolic compounds were extracted with methanol and extracts were analyzed by HPLC-DAD-MS/MS. During ripening, four different changing patterns were observed: (1) high level in green fruits with minimal changes; (2) continuous increase with maximum level in red-ripe fruits; (3) decrease; (4) increase and achieving maximum level at half-ripe stage. Similar change patterns were found for organic and conventional fruits. The accumulation patterns of phenolic compounds were similar in standard-type tomatoes but differed in several cases in cherry-type cultivar. Although contents of some polyphenols decreased during ripening, total phenolics and free radical scavenging activity increased in all studied cultivars and in case of both cultivationmodes. The changes in content of phenolic compounds during ripening were greatly influenced by cultivars, but cultivation mode had only minor impact on dynamics in polyphenols contents in tomato fruits.
  • Mäkelä, Miia R.; Dilokpimol, Adiphol; Koskela, Salla M.; Kuuskeri, Jaana; de Vries, Ronald P.; Hilden, Kristiina (2018)
    Feruloyl esterases (FAEs) are accessory enzymes for plant biomass degradation, which catalyse hydrolysis of carboxylic ester linkages between hydroxycinnamic acids and plant cell-wall carbohydrates. They are a diverse group of enzymes evolved from, e.g. acetyl xylan esterases (AXEs), lipases and tannases, thus complicating their classification and prediction of function by sequence similarity. Recently, an increasing number of fungal FAEs have been biochemically characterized, owing to their potential in various biotechnological applications and multitude of candidate FAEs in fungal genomes. However, only part of the fungal FAEs are included in Carbohydrate Esterase family 1 (CE1) of the carbohydrate-active enzymes (CAZy) database. In this work, we performed a phylogenetic analysis that divided the fungal members of CE1 into five subfamilies of which three contained characterized enzymes with conserved activities. Conservation within one of the subfamilies was confirmed by characterization of an additional CE1 enzyme from Aspergillus terreus. Recombinant A.terreus FaeD (AtFaeD) showed broad specificity towards synthetic methyl and ethyl esters, and released ferulic acid from plant biomass substrates, demonstrating its true FAE activity and interesting features as potential biocatalyst. The subfamily division of the fungal CE1 members enables more efficient selection of candidate enzymes for biotechnological processes.
  • Kapp, Karmen; Püssa, Tõnu; Orav, Anne; Roasto, Mati; Raal, Ain; Vuorela, Pia; Vuorela, Heikki; Tammela, Päivi (2020)
    Mentha spp. are used in the food and pharmaceutical industry; the plants are characterized by natural interspecies hybridization. In this study, knowledge of the chemical composition of Mentha spp. was broadened by focusing on plants grown in a geographically small region of Estonia. The antibacterial activity of Mentha spp. essential oils and water extracts was evaluated. Polyphenolic water extracts of M. x villosa Huds., M. x suaveolens Ehrh., and M. x gracilis Sole were tested for the first time on Escberichia coli and Staphylococcus aura's. Leaves of cultivated and wild-grown plants (n = 33) were collected. The microdistilled essential oil composition reflected the diversity within the genus Mentha. Determined by gas chromatography-mass spectrometry (MS), major compounds were cis-piperitone oxide, carvone, linalool, menthol, and menthofuran. Based on high-performance liquid chromatographyultraviolet-MS/MS analyses of the water extracts, no species-specific polyphenolic compounds could be proposed. Abundant polyphenols were rosmarinic acid, salvianolic acid B, and eriocitrin. Essential oils exhibited antibacterial activity on E. coli and S. aureus by the broth dilution method. Water extracts showed activity only against S. aureus. This study supports the use of Mentha spp. as health-promoting ingredients in food. However, further studies are still needed to widen the knowledge of the chemical composition of these plants.
  • Wang, Liang; Li, Menglu; Bu, Qian; Li, Hongchun; Xu, Wei; Liu, Chunqi; Gu, Hui; Zhang, Jiamei; Wan, Xuemei; Zhao, Yinglan; Cen, Xiaobo (2019)
    Much efforts have been tried to clarify the molecular mechanism of alcohol-induced brain damage from the perspective of genome and protein; however, the effect of chronic alcohol exposure on global lipid profiling of brain is unclear. In the present study, by using Q-TOF/MS-based lipidomics approach, we investigated the comprehensive lipidome profiling of brain from the rats orally administrated with alcohol daily, continuously for one year. Through systematically analysis of all lipids in prefrontal cortex (PFC) and striatum region, we found that long-term alcohol exposure profoundly modified brain lipidome profiling. Notably, three kinds of lipid classes, glycerophospholipid (GP), glycerolipid (GL) and fatty acyls (FA), were significantly increased in these two brain regions. Interestingly, most of the modified lipids were involved in synthetic pathways of endoplasmic reticulum (ER), which may result in ER stress-related metabolic disruption. Moreover, alcohol-modified lipid species displayed long length of carbon chain with high degree of unsaturation. Taken together, our results firstly present that chronic alcohol exposure markedly modifies brain lipidomic profiling, which may activate ER stress and eventually result in neurotoxicity. These findings provide a new insight into the mechanism of alcohol-related brain damage.
  • Riva, M.; Ehn, M.; Li, D.; Tomaz, S.; Bourgain, F.; Perrier, S.; George, C. (2019)
    While acknowledged as key components in the formation of new particles in the atmosphere, the accurate characterization of gaseous (highly) oxygenated organic compounds remains challenging and requires analytical developments. Earlier studies have successfully used the nitrate ion (NO3) based chemical ionization (CI) coupled to atmospheric pressure interface time-of-flight mass spectrometry (CI-APi-TOF) for monitoring these compounds. Despite many breakthroughs in recent years, the CI-APi-TOF has many limitations, preventing for instance the unambiguous ion identification of overlapping peaks. To tackle this analytical challenge, we developed a CI interface coupled to an ultrahigh-resolution Orbitrap mass spectrometer (CI-Orbitrap). We show that the CI-Orbitrap has similar sensitivity and selectivity as the CI-APi-TOF, but with over an order of magnitude higher mass resolving power (up to 140 000). Equally importantly, the CI-Orbitrap allows tandem mass spectrometry, providing the possibility for structural elucidation of the highly oxygenated organic molecules (HOM). As a proof of concept, we characterized HOM formed during the ozonolysis of two biogenic compounds (alpha-pinene and limonene), under different environmental conditions in a flow reactor. The CI-Orbitrap exhibited high sensitivity to both HOM and radical species, while easily separating ions of different elemental composition in cases where the more common TOF applications would not have been able to distinguish all ions. Our tandem mass spectrometry analyses revealed distinct fingerprint spectra for all the studied HOM. Overall, the CI-Orbitrap is an extremely promising instrument, and it provides a much-needed extension to ongoing research on HOM, with potential to impact also many other fields within atmospheric chemistry.
  • Rasouli, B.; Ahlqvist, E.; Alfredsson, L.; Andersson, T.; Carlsson, P.-O.; Groop, L.; Löfvenborg, J.E.; Martinell, M.; Rosengren, A.; Tuomi, T.; Wolk, A.; Carlsson, S. (2018)
    Aim. - Coffee consumption is inversely related to risk of type 2 diabetes (T2D). In contrast, an increased risk of latent autoimmune diabetes in adults (LADA) has been reported in heavy coffee consumers, primarily in a subgroup with stronger autoimmune characteristics. Our study aimed to investigate whether coffee consumption interacts with HLA genotypes in relation to risk of LADA. Methods. - This population-based study comprised incident cases of LADA (n = 484) and T2D (n = 1609), and also 885 healthy controls. Information on coffee consumption was collected by food frequency questionnaire. Odds ratios (ORs) with 95% CIs of diabetes were calculated and adjusted for age, gender, BMI, education level, smoking and alcohol intake. Potential interactions between coffee consumption and high-risk HLA genotypes were calculated by attributable proportion (AP) due to interaction. Results. - Coffee intake was positively associated with LADA in carriers of high-risk HLA genotypes (OR: 1.14 per cup/day, 95% CI: 1.02-1.28), whereas no association was observed in non-carriers (OR: 1.04, 95% CI: 0.93-1.17). Subjects with both heavy coffee consumption (>= 4 cups day) and high-risk HLA genotypes had an OR of 5.74 (95% Cl: 3.34-9.88) with an estimated AP of 0.36 (95% CI: 0.01-0.71; P = 0.04370). Conclusion. - Our findings suggest that coffee consumption interacts with HLA to promote LADA. (C) 2018 Elsevier Masson SAS. All rights reserved.
  • Hedenbjork-Lager, Anders; Hamberg, Kristina; Paakkonen, Virve; Tjaderhane, Leo; Ericson, Dan (2016)
    Objective: Dental caries is a process driven by acids produced by oral microorganisms followed by degradation of the dentine collagen matrix by proteolytic enzymes. Matrix metalloproteinases (MMPs) have been suggested to contribute to caries by degrading collagen. The aim of this study was to develop a method for generating demineralized dentine matrix substrate (DDM) maintaining MMP-8 bioactivity and no interference with later assays. Such a substrate would allow study of the effects of various treatments on MMP-8 activity and collagen degradation in demineralized dentine. Design: Human dentine was powderized in a tissue grinder and frozen (-80 degrees C). The powder was demineralized in dialysis tubes, using EDTA or acetic acid. The demineralized dentine matrix (DDM) was harvested and analyzed for collagen content using SDS-PAGE. The DDM was subsequently suspended in PBS or TESCA buffer. Protein, MMP-8 (ELISA) and collagen (HYP) was analyzed directly or after 1 wk. Results: EDTA or acid demineralization of dentine using dialysis yielded a substrate rich in collagen coupled with preserved MMP-8 activity. Collagen degraded in room temperature, assessed by higher HYP amounts in the soluble fraction of DDM after one wk, indicating that the methods used preserved active DDM-components after the demineralization process. Conclusions: The presented demineralization methods both provided insoluble DDM substrates suitable for further intervention studies. However, it was found that the substrates differed depending on the demineralization method and buffers used. This needs further study to find an optimal technique for generating DDM with retained proteins as well as enzymatic bioactivity. (C) 2016 Elsevier Ltd. All rights reserved.
  • Lindström, Mikael; Tohmola, Niina; Renkonen, Risto; Hämäläinen, Esa; Schalin-Jäntti, Camilla; Itkonen, Outi (2018)
    Background: Serotonin (5-hydroxytyramine) is a mediator of gastrointestinal smooth muscle contraction, and is secreted by neuroendocrine neoplasms (NENs). We developed a liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for serum serotonin to be used in NEN diagnostics and follow-up. Methods: We used serum samples from healthy volunteers (n = 31) and patients suspected or monitored for NEN (n = 98). Serotonin-D-4 internal standard was added to samples before solid phase extraction (SPE) and quantification by LC-MS/MS. The effects of sample handling and preparation on serotonin stability were studied. Finally, we established a provisional reference range for serum serotonin and compared our assay with serum 5hydroxyindoleacetic acid (5-HIAA) for detection of NENs. Results: Our assay is sensitive and has a wide linear range (10-10,000 nmo1/1). Serum serotonin is stable for 7 days at room temperature and for 3 months at -20 degrees C. Sampling temperature is not critical. Normal range for serum serotonin was 270-1490 nmo1/1. We found that serum serotonin and 5-HIAA performed equally well as diagnostic tests for NENs. Conclusions: Our LC-MS/MS assay for serum serotonin is well suited for clinical research and patient diagnostics. Our results confirm that it can complement 5-HIAA in diagnosis of NENs.
  • Iyer, Siddharth; He, Xucheng; Hyttinen, Noora; Kurten, Theo; Rissanen, Matti P. (2017)
    The HO2 radical is an important atmospheric molecule that can potentially influence the termination of autoxidation processes of volatile organic compounds (VOCs) that lead to the formation of highly oxygenated multifunctional compounds (HOMs). In this work, we demonstrate the direct detection of the HO2 radical using an iodide-based chemical ionization mass spectrometer (iodide-CIMS). Expanding on the previously established correlation between molecule-iodide binding enthalpy and iodide-CIMS instrument sensitivity, the experimental detection of the HO2 radical was preceded by the quantum chemical calculation of the HO2*I- cluster (PBE/aug-cc-pVTZ-PP level), which showed a reasonably strong binding enthalpy of 21.60 kcal/mol. Cyclohexene ozonolysis intermediates and closed-shell products were next detected by the iodide-CIMS. The ozone-initiated cyclohexene oxidation mechanism was perturbed by the introduction of the HO2 radical, leading to the formation of closed-shell hydroperoxides. The experimental investigation once again followed the initial computational molecule-iodide binding enthalpy calculations. The quantum chemical calculations were performed at the PBE/aug-cc-pVTZ-PP level for radicals and DLPNO-CCSD(T)/def2-QZVPP//PBE/aug-cc-pVTZ-PP level for the closed-shell products. A comparison between the iodide-CIMS and nitrate-CIMS spectra with identical measurement steps revealed that the iodide-CIMS was able to detect the low-oxidized (O/C ratio 0.5 and 0.66) cyclohexene ozonolysis monomer products more efficiently than nitrate-CIMS. Higher-oxidized monomers (O/C ratio 1 to 1.5) were detected equally well by both methods. An investigation of dimers showed that both iodide- and nitrate-CIMS were able to detect the dimer compositions possibly formed from reactions between the peroxy radical monomers considered in this study. Additionally, iodide-CIMS detected organic ions that were formed by a previously suggested mechanism of dehydroxylation of peroxy acids (and deoxygenation of acyl peroxy radicals) by H2O*I- clusters. These mechanisms were computationally verified.
  • Parmentier, Dries; Paradis, Sarah; Metz, Sybrand J.; Wiedmer, Susanne K.; Kroon, Maaike C. (2016)
    This work describes for the first time a continuous process for selective metal extraction with an ionic liquid (IL) at room temperature. The hydrophobic fatty acid based IL tetraoctylphosphonium oleate ([P-8888][oleate]) was specifically chosen for its low viscosity and high selectivity towards transition metals. Applying [P-8888][oleate] for continuous metal ion extraction with 0.1 M sodium oxalate for regeneration resulted in a process with good and stable extraction efficiencies over time. The selectivity of the IL resulted in a process in which cobalt was selectively removed from two mixed salt solutions (Co/Na, Ca/Co/K) to obtain a pure cobalt stream after stripping the IL. The performed experiments showed that the contact time of the IL for extraction and stripping strongly influenced the achieved efficiencies. The stability of the IL was tested and it was shown that the fatty acid based IL was stable for the duration of the experiment. Liposome tests showed that the IL is very hydrophobic, which limits its leakage towards the water phase, but also results in a higher toxicity towards cell membranes. Economic analysis shows that the IL based process is not (yet) economical compared to ion-exchange resins, in case demineralised water is the only product. However, if the recovery of valuable metals is also taken into account and/or if brine disposal is an issue, then continuous IL metal extraction systems must be regarded as promising alternatives. (C) 2016 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.