scholarly journals Simultaneous quantification of trimethylamine N-oxide, trimethylamine, choline, betaine, creatinine, and propionyl-, acetyl-, and l-carnitine in clinical and food samples using HILIC-LC-MS

2021 ◽  
Author(s):  
Mohammed E Hefni ◽  
Maria Bergström ◽  
Torbjörn Lennqvist ◽  
Cecilia Fagerström ◽  
Cornelia M Witthöft
Keyword(s):  
Acid Hydrolysis ◽  
Mobile Phase ◽  
Food Samples ◽  
The Other ◽  
Clinical Samples ◽  
Food Ingestion ◽  
Intervention Trial ◽  
Internal Standards ◽  
External Calibration ◽  
Simultaneous Quantification

AbstractTrimethylamine-N-oxide (TMAO), a microbiome-derived metabolite from the metabolism of choline, betaine, and carnitines, is associated to adverse cardiovascular outcomes. A method suitable for routine quantification of TMAO and its precursors (trimethylamine (TMA), choline, betaine, creatinine, and propionyl-, acetyl-, and l-carnitine) in clinical and food samples has been developed based on LC-MS. TMA was successfully derivatized using iodoacetonitrile, and no cross-reactions with TMAO or the other methylamines were detected. Extraction from clinical samples (plasma and urine) was performed after protein precipitation using acetonitrile:methanol. For food samples (meatballs and eggs), water extraction was shown to be sufficient, but acid hydrolysis was required to release bound choline before extraction. Baseline separation of the methylamines was achieved using a neutral HILIC column and a mobile phase consisting of 25 mmol/L ammonium formate in water:ACN (30:70). Quantification was performed by MS using external calibration and isotopic labelled internal standards. The assay proved suitable for both clinical and food samples and was linear from ≈ 0.1 up to 200 μmol/L for all methylamines except for TMA and TMAO, which were linear up to 100 μmol/L. Recoveries were 91–107% in clinical samples and 76–98% in food samples. The interday (n=8, four duplicate analysis) CVs were below 9% for all metabolites in clinical and food samples. The method was applied successfully to determine the methylamine concentrations in plasma and urine from the subjects participating in an intervention trial (n=10) to determine the effect of animal food ingestion on methylamine concentrations. Graphical abstract

scholarly journals Method validation for simultaneous quantification of some Human Milk Oligosaccharides (HMOs) in dietary supplements by liquid chromatography tandem mass spectrometry (LC-MS/MS)

2021 ◽  
Vol 4 (1) ◽  
pp. 24-26
Author(s):  
Hong Ngoc Nguyen Thi ◽  
Thanh Hoa Mac Thi ◽  
Son Tran Hung ◽  
Dung Ngo Manh ◽  
Khanh Cao Cong ◽  
...  
Keyword(s):  
Human Milk ◽  
Dietary Supplements ◽  
Mobile Phase ◽  
Food Samples ◽  
Phase System ◽  
Time Analysis ◽  
Simultaneous Quantification ◽  
Chromatography Tandem Mass Spectrometry ◽  
Validation Parameters ◽  
Liquid Chromatography Tandem Mass

The method of simultaneous quantification some of Human Milk Oligosaccharide in dietary supplements by LC-MS/MS is an accurate and effective method to quickly determine the content of 2'-Fucosyllactose (2 '-FL), Lacto-N-neotetraose (LNnT), Lacto-N-tetraose (LNT), 3'-Siallylactose (3'-SL) and 6'-Siallylactose (6'-SL) in both dietary supplements powder and liquid. The method has been developed and validated follow the AOAC International guidelines. The mobile phase system consists of 2 channels: channel A (0.1% formic acid) and channel B (acetonitril) connected to the HILIC column (3.5 μm, 2.1mm × 150 mm) and the MS detector. The time analysis is 10 minutes, this method can identify all 5 substances belonging to the group HMOs. The detection limit and quantitative limit for all 5’-FL, LNnT, LNT, 3’-SL, 6’-SL were 4 mg/kg and 10 mg/kg, respectively. The linear range of the method ranges from 0.4 µg/mL to 40 µg/mL. Other validation parameters include the accuracy (R% 98.8 -103%); The precision (RSD% 1.69 - 5.54%) can meet the requirement of AOAC. The method was applied in practice to analyze 25 supplementary food samples on the market gives the results of analyzing total HMOs in powdered samples about 0.1 – 0.3 g/100g and for liquid samples about 0.01 – 0.03 g/100mL.

scholarly journals Development of a LC-MS/MS method using stable isotope dilution for the quantification of individual B6 vitamers in fruits, vegetables, and cereals

2020 ◽  
Vol 412 (26) ◽  
pp. 7237-7252
Author(s):  
Thomas Bachmann ◽  
Andrea Maurer ◽  
Michael Rychlik
Keyword(s):  
Stable Isotope ◽  
Isotope Dilution ◽  
Food Samples ◽  
Vitamin B ◽  
Internal Standards ◽  
Stable Isotope Dilution ◽  
Simultaneous Quantification ◽  
Isotope Dilution Assay ◽  
Dilution Assay ◽  
Detection And Quantification

Abstract Vitamin B6 comprises an important set of molecules tightly interwoven with the human amino acid, fatty acid, and carbohydrate metabolism. Analytical methods striving for the quantification of individual B6 vitamers so far mostly rely on methods based on HPLC in combination with fluorescence detection, but their application encounters multiple difficulties due to the chemical divergence of the single vitamers. The present study describes the development of a method based on LC-MS/MS and stable isotope dilution assay (SIDA) for the simultaneous quantification of five vitamers (PN, PL, PM, PMP, and PNG) of the B6 group in food samples. [13C3]-PN, [13C3]-PL, and [13C6]-PNG were applied as internal standards for the analysis of PN, PL, and PNG. PM and PMP were quantified via matrix-matched calibration referring to [13C3]-PN. The developed method was validated using starch matrix. The limits of detection and quantification ranged from 0.0028 to 0.02 mg/kg and from 0.0085 to 0.059 mg/kg, respectively, for all analytes. Calculated recoveries varied from 92 to 111%. Intra-injection precisions ranged from 0 to 9%, inter-day precisions from 4 to 10%, and intra-day precisions from 4 to 10%. A total of 14 plant-based food samples including fruits, vegetables, and cereals were examined for their content of vitamin B6 using the validated method. Furthermore, the first quantitation of PNG without enzymatic steps or divergent internal standards was undertaken utilizing LC-MS/MS and SIDA.

scholarly journals Stability-indicating HPLC-DAD assay for simultaneous quantification of hydrocortisone 21 acetate, dexamethasone, and fluocinolone acetonide in cosmetics

2020 ◽  
Vol 18 (1) ◽  
pp. 962-973
Author(s):  
Saira Arif ◽  
Sadia Ata
Keyword(s):  
Mobile Phase ◽  
Limit Of Detection ◽  
Fluocinolone Acetonide ◽  
Internal Diameter ◽  
Forced Degradation ◽  
Specific Method ◽  
Regression Equations ◽  
Limit Of Quantification ◽  
Simultaneous Quantification ◽  
Relative Standard

AbstractA rapid and specific method was developed for simultaneous quantification of hydrocortisone 21 acetate (HCA), dexamethasone (DEX), and fluocinolone acetonide (FCA) in whitening cream formulations using reversed-phase high-performance liquid chromatography. The effect of the composition of the mobile phase, analysis temperature, and detection wavelength was investigated to optimize the separation of studied components. The analytes were finally well separated using ACE Excel 2, C18 AR column having 150 mm length, 3 mm internal diameter, and 2 µm particle size at 35°C using methanol with 1% formic acid and double-distilled deionized water in the ratio of 60:40 (v/v), respectively, as the mobile phase in isocratic mode. Ten microliters of sample were injected with a flow rate of 0.5 mL/min. The specificity, linearity, accuracy, precision, recovery, limit of detection (LOD), limit of quantification (LOQ), and robustness were determined to validate the method as per International Conference on Harmonization guidelines. All the analytes were simultaneously separated within 8 min, and observed retention times of HCA, DEX, and FCA were 4.5, 5.5, and 6.9 min, respectively. The proposed method showed good linearity with the correlation coefficient, R2 = 0.999 over the range of 1–150 µg/mL for all standards. The linear regression equations were y = 12.7x + 118.7 (r = 0.999) for HCA, y = 12.9x + 106.8 (r = 0.999) for DEX, and y = 12.9x + 96.8 (r = 0.999) for FCA. The LOD was 0.25, 0.20, and 0.08 µg/mL for HCA, FCA, and DEX and LOQ was 2.06, 1.83, and 1.55 µg/mL for HCA, FCA, and DEX, respectively. The recovery values of HCA, DEX, and FCA ranged from 100.7–101.3, 102.0–102.6, and 100.2–102.0%, respectively, and the relative standard deviation for precision (intra- and interday) was less than 2, which indicated repeatability and reproducibility. The novelty of the method was described by forced degradation experimentation of all analytes in the combined form under acidic, basic, oxidative, and thermal stress. The proposed method was found to be simple, rapid, and reliable for the simultaneous determination of HCA, DEX, and FCA in cosmetics.

scholarly journals Purification and characterization of bacteriocins-like inhibitory substances from food isolated Enterococcus faecalis OS13 with activity against nosocomial enterococci

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ahmed O. El-Gendy ◽  
Dag A. Brede ◽  
Tamer M. Essam ◽  
Magdy A. Amin ◽  
Shaban H. Ahmed ◽  
...  
Keyword(s):  
Enterococcus Faecalis ◽  
Antimicrobial Agents ◽  
Food Samples ◽  
Proteinase K ◽  
Clinical Samples ◽  
Bile Salt Hydrolase ◽  
Antibiotic Resistant ◽  
Molecular Weights ◽  
Global Threat

AbstractNosocomial infections caused by enterococci are an ongoing global threat. Thus, finding therapeutic agents for the treatment of such infections are crucial. Some Enterococcus faecalis strains are able to produce antimicrobial peptides called bacteriocins. We analyzed 65 E. faecalis isolates from 43 food samples and 22 clinical samples in Egypt for 17 common bacteriocin-encoding genes of Enterococcus spp. These genes were absent in 11 isolates that showed antimicrobial activity putatively due to bacteriocins (three from food, including isolate OS13, and eight from clinical isolates). The food-isolated E. faecalis OS13 produced bacteriocin-like inhibitory substances (BLIS) named enterocin OS13, which comprised two peptides (enterocin OS13α OS13β) that inhibited the growth of antibiotic-resistant nosocomial E. faecalis and E. faecium isolates. The molecular weights of enterocin OS13α and OS13β were determined as 8079 Da and 7859 Da, respectively, and both were heat-labile. Enterocin OS13α was sensitive to proteinase K, while enterocin OS13β was resistant. Characterization of E. faecalis OS13 isolate revealed that it belonged to sequence type 116. It was non-hemolytic, bile salt hydrolase-negative, gelatinase-positive, and sensitive to ampicillin, penicillin, vancomycin, erythromycin, kanamycin, and gentamicin. In conclusion, BLIS as enterocin OS13α and OS13β represent antimicrobial agents with activities against antibiotic-resistant enterococcal isolates.

scholarly journals Mass Spectrometry and Multiplex Antigen Assays to Assess Microbial Quality and Toxin Production ofStaphylococcus aureusStrains Isolated from Clinical and Food Samples

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Paul Attien ◽  
Haziz Sina ◽  
Wardi Moussaoui ◽  
Gaëlle Zimmermann-Meisse ◽  
Thomas Dadié ◽  
...  
Keyword(s):  
Meat Product ◽  
Meat Products ◽  
Toxin Production ◽  
Food Samples ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Microbial Quality ◽  
Meat Samples ◽  
Panton Valentine Leukocidin

The aim of our study was to investigate the microbial quality of meat products and on some clinical samples in Abidjan focused onStaphylococcusgenus and the toxin production profile ofStaphylococcus aureus(S. aureus) isolated. Bacteria were collected from 240 samples of three meat products sold in Abidjan and 180 samples issued from clinical infections. The strains were identified by both microbiological and MALDI-TOF-MS methods. The susceptibility to antibiotics was determined by the disc diffusion method. The production of Panton-Valentine Leukocidin, LukE/D, and epidermolysins was screened using radial gel immunodiffusion. The production of staphylococcal enterotoxins and TSST-1 was screened by a Bio-Plex Assay. We observed that 96/240 of meat samples and 32/180 of clinical samples were contaminated byStaphylococcus. Eleven species were isolated from meats and 4 from clinical samples. Forty-twoS. aureusstrains were isolated from ours samples. Variability of resistance was observed for most of the tested antibiotics but none of the strains displays a resistance to imipenem and quinolones. We observed that 89% of clinicalS. aureuswere resistant to methicillin against 58% for those issued from meat products. AllS. aureusisolates issued from meat products produce epidermolysins whereas none of the clinical strains produced these toxins. The enterotoxins were variably produced by both clinical and meat product samples.

scholarly journals The evolution of regulatory elements in the emerging promoter variant strains of HIV-1

2021 ◽  
Author(s):  
Disha Bhange ◽  
Nityanand Prasad ◽  
Swati Singh ◽  
Harshit Kumar Prajapati ◽  
Shesh Prakash Maurya ◽  
...  
Keyword(s):  
Viral Latency ◽  
Regulatory Elements ◽  
The Other ◽  
Clinical Samples ◽  
Latent Reservoir ◽  
Viral Gene ◽  
Viral Promoter ◽  
Reservoir Characteristics ◽  
Hiv 1

AbstractIn a multicentric, observational, investigator-blinded, and longitudinal clinical study of 764 ART-naïve subjects, we identified nine different promoter-variant strains of HIV-1 subtype C (HIV-1C) emerging in the Indian population, with some of these variants being reported for the first time. Unlike several previous studies, our work here focuses on the evolving viral regulatory elements, not coding sequences. The emerging viral strains contain additional copies of the existing transcription factor binding sites (TFBS), including TCF-1α/LEF-1, RBEIII, AP-1, and NF-κB, created by sequence duplication. The additional TFBS are genetically diverse and may blur the distinction between the modulatory region of the promoter and the viral enhancer. In a follow-up analysis, we found trends, but not significant associations between any specific variant promoter and prognostic markers, probably because the emerging viral strains might not have established mono infections yet. Illumina sequencing of four clinical samples containing a co-infection indicated the domination of one strain over the other and establishing a stable ratio with the second strain at the follow-up time-points. Since a single promoter regulates viral gene expression and constitutes the master regulatory circuit with Tat, the acquisition of additional and variant copies of the TFBS may significantly impact viral latency and latent reservoir characteristics. Further studies are urgently warranted to understand how the diverse TFBS profiles of the viral promoter may modulate the characteristics of the latent reservoir, especially following the initiation of antiretroviral therapy.Significance StatementA unique conglomeration of TFBS enables the HIV-1 promoter to accomplish two diametrically opposite functions – transcriptional activation and transcriptional silencing. The various phases of viral latency - establishment, maintenance, and reversal - collectively determine the replication fitness of individual viral strains. A profound variation in the TFBS composition of the viral promoter may significantly alter the viral latency properties and the latent reservoir characteristics. Although the duplication of certain TFBS remains a quality unique to HIV-1C, the high-level genetic recombination of HIV-1 may promote the transfer of such molecular properties to the other HIV-1 subtypes. The emergence of several promoter-variant viral strains may make the task of a ‘functional cure’ more challenging in HIV-1C.

Commercial Latex Agglutination Kits for the Detection of Food borne Salmonella

1991 ◽  
Vol 54 (9) ◽  
pp. 725-730 ◽  
Author(s):  
J.-Y. D'AOUST ◽  
A. M. SEWELL ◽  
P. GRECO
Keyword(s):  
Food Samples ◽  
Latex Agglutination ◽  
Clinical Samples ◽  
Salmonella Spp ◽  
Concurrent Use ◽  
Food Borne ◽  
Analytical Test ◽  
Contaminated Food ◽  
Pure Cultures ◽  
Vi Antigen

The ability of the Bactigen® Salmonella Shigella (BSST), the Microscreen® (MS), and the Spectate® (SPECT) latex agglutination kits to detect Salmonella in pure cultures and in naturally contaminated foods was examined. Of 190 Salmonella strains tested, the MS, BSST, and SPECT systems correctly identified 89.5, 81.6, and 66.3% of the test cultures, respectively. The sensitivity of SPECT increased to 92.7% when only strains belonging to the targeted serogroups (somatic A to E plus G) and strains harboring the Vi antigen were considered. The lack of specificity of the MS (3.4%), SPECT (17.0%), and BSST (33.9%) systems with 59 cultures of nonsalmonellae varied widely, with Citrobacter freundii and Escherichia coli accounting for many of the false-positive reactions. Examination of foods according to the prescribed MS and SPECT analytical test protocols identified respectively, 18 (75%) and 19 (79.2%) of the 24 food samples found to contain Salmonella spp. by a standard cultural method. Although instructions with the BSST kit indicate that the product is intended for the analysis of clinical samples, the system nevertheless identified 21 (87.5%) contaminated food samples under homologous MS and SPECT test conditions. The concurrent use of TBG43 with enrichment media recommended by kit manufactures enhanced the sensitivities of MS (83.3%), SPECT (91.7%), and BSST (91.7%). Attempts to effect greater method brevity through the application of latex kits at various stages of the standard cultural procedure were counterproductive.

scholarly journals Simultaneous Quantification of Panax and Epimedium Species Using Rapid Resolution Liquid Chromatography (RRLC)

2011 ◽  
Vol 6 (5) ◽  
pp. 1934578X1100600 ◽  
Author(s):  
Jie Ma ◽  
Yuan-Chun Ma ◽  
Daniel Wang ◽  
Fei Fei Hou ◽  
Mai Luo ◽  
...  
Keyword(s):  
Quality Control ◽  
Liquid Chromatography ◽  
Flow Rate ◽  
Mobile Phase ◽  
Pure Water ◽  
Complex Mixtures ◽  
Rapid Resolution ◽  
Simultaneous Quantification ◽  
Panax Species ◽  
Reference Samples

Two Rapid Resolution Liquid Chromatography (RRLC) methods have been developed and validated for simultaneous quantification of eight major ginsenosides from Panax species, namely, R1, Rg1, Re, Rf, Rb1, Rb2, Rc, and Rd, and flavonoids from Epimedium species, namely, epimedins A, B, and C and icariin. The analyses were performed using an Agilent 1200 series RRLC system with Phenomenex Luna C18-HST and Zorbax Eclipse XDB columns. The separation was performed with a gradient mobile phase of A (pure water) and B (acetonitrile) at a flow rate of 1.0 mL/ min and 2.5 mL/min, respectively. Both columns were kept at 40°C with the detection wavelength set at 203 nm. Specific eluted compounds were identified by using reference samples of ginsenosides R1, Rg1, Re, Rf, Rb1, Rc, Rb2, and Rd, and epimedins A, B, C and icariin. Baseline separation was achieved in less than 15 minutes for the Phenomenex Luna column and 4 minutes for the Zorbax Eclipse column. Characteristic RRLC profiles were established for complex mixtures of ginsenosides from Panax species and flavonoids from Epimedium species. Both methods developed here are effective for the quality control of formulated products containing both Panax and Epimedium varieties.

Comparative Assessment of Fumonisin in Grain-Based Foods by ELISA, GC-MS, and HPLC

1994 ◽  
Vol 57 (2) ◽  
pp. 169-172 ◽  
Author(s):  
JAMES J. PESTKA ◽  
JUAN I. AZCONA-OLIVERA ◽  
RONALD D. PLATTNER ◽  
FIORENZA MINERVINI ◽  
M. BRUNO DOKO ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Monoclonal Antibody ◽  
Food Samples ◽  
Comparative Assessment ◽  
The Other ◽  
Gas Chromatography Mass Spectrometry ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cereal Samples ◽  
Related Compounds ◽  
Positive Results

Seventy-one (71) food samples were analyzed for the mycotoxin fumonisin by a monoclonal antibody based competitive enzyme-linked immunosorbent assay (ELISA). Fumonisins were detected primarily in corn-based products with 7/12, 2/2 and 1/3 and 1/7 yellow cornmeal, blue cornmeal, corn muffin mix, and mixed grain cereal samples yielding positive results, respectively. When the positive samples and randomly selected negative samples were assessed by other methods, correlations (r values) between ELISA and gas chromatography-mass spectrometry (GC-MS), ELISA and high-pressure liquid chromatography (HPLC) and GC-MS and HPLC were 0.478 (p < 0.05), 0.512 (p < 0.05), and 0.946 (p < 0.01), respectively. The results suggested that although the immunoassay could be used for screening of fumonisin in food samples, higher estimates were attained by ELISA than by the other two methods particularly in the more contaminated samples. These observations may result from differences in sample preparation among the methods or because of the presence of structurally related compounds in extracts that are detectable by ELISA but not the other two methods.

Structure of Depression in Black Alcoholic Men

1977 ◽  
Vol 41 (3_suppl) ◽  
pp. 1235-1241 ◽  
Author(s):  
Robert A. Steer ◽  
Brian F. Shaw ◽  
Aaron T. Beck ◽  
Eric W. Fine
Keyword(s):  
Maximum Likelihood ◽  
Black Men ◽  
Beck Depression Inventory ◽  
Factor Structure ◽  
Outpatient Treatment ◽  
The Other ◽  
Clinical Samples ◽  
Factor Analyses ◽  
Depressed Patients

The Beck Depression Inventory was self-administered to 103 black men receiving outpatient treatment for alcoholism, and scores were subjected to factor analyses using a maximum-likelihood solution. Three meaningful oblique dimensions were identified as Cognitive-affective Impairment, Retarded Depression, and Escapism. The factor structure of the black alcoholic men was descriptively compared to those previously reported for racially heterogeneous alcoholic patients and for primarily depressed patients; the factors of depression for the black alcoholic men were comparable to those described for the other two clinical samples.

Sign in / Sign up

Export Citation Format

Share Document