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Dr. Dragan Isailovic
Department of Chemistry and Biochemistry, University of Toledo, Toledo, OH 43606, USA

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0 Lipids
0 proteins
0 Development and applications of separation and mass spectrometry (MS) methods for qualitative and quantitative analyses of cyanotoxins and other biomolecules
0 Such as peptides
0 And glycans.

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proteins
Development and applications of separation and mass spectrometry (MS) methods for qualitative and quantitative analyses of cyanotoxins and other biomolecules

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Journal article
Published: 08 April 2021 in Plants
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The response of plant N relations to the combination of elevated CO2 (eCO2) and warming are poorly understood. To study this, tomato (Solanum lycopersicum) plants were grown at 400 or 700 ppm CO2 and 33/28 or 38/33 °C (day/night), and their soil was labeled with 15NO3 − or 15NH4 +. Plant dry mass, root N-uptake rate, root-to-shoot net N translocation, whole-plant N assimilation, and root resource availability (%C, %N, total nonstructural carbohydrates) were measured. Relative to eCO2 or warming alone, eCO2 + warming decreased growth, NO3 − and NH4 +-uptake rates, root-to-shoot net N translocation, and whole-plant N assimilation. Decreased N assimilation with eCO2 + warming was driven mostly by inhibition of NO3 − assimilation, and was not associated with root resource limitations or damage to N-assimilatory proteins. Previously, we showed in tomato that eCO2 + warming decreases the concentration of N-uptake and -assimilatory proteins in roots, and dramatically increases leaf angle, which decreases whole-plant light capture and, hence, photosynthesis and growth. Thus, decreases in N uptake and assimilation with eCO2 + warming in tomato are likely due to reduced plant N demand.

ACS Style

Dileepa Jayawardena; Scott Heckathorn; Krishani Rajanayake; Jennifer Boldt; Dragan Isailovic. Elevated Carbon Dioxide and Chronic Warming Together Decrease Nitrogen Uptake Rate, Net Translocation, and Assimilation in Tomato. Plants 2021, 10, 722 .

AMA Style

Dileepa Jayawardena, Scott Heckathorn, Krishani Rajanayake, Jennifer Boldt, Dragan Isailovic. Elevated Carbon Dioxide and Chronic Warming Together Decrease Nitrogen Uptake Rate, Net Translocation, and Assimilation in Tomato. Plants. 2021; 10 (4):722.

Chicago/Turabian Style

Dileepa Jayawardena; Scott Heckathorn; Krishani Rajanayake; Jennifer Boldt; Dragan Isailovic. 2021. "Elevated Carbon Dioxide and Chronic Warming Together Decrease Nitrogen Uptake Rate, Net Translocation, and Assimilation in Tomato." Plants 10, no. 4: 722.

Journal article
Published: 19 April 2020 in Toxins
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A method was developed to extract and quantify microcystins (MCs) from mouse liver with limits of quantification (LOQs) lower than previously reported. MCs were extracted from 40-mg liver samples using 85:15 (v:v) CH3CN:H2O containing 200 mM ZnSO4 and 1% formic acid. Solid-phase extraction with a C18 cartridge was used for sample cleanup. MCs were detected and quantified using HPLC-orbitrap-MS with simultaneous MS/MS detection of the 135.08 m/z fragment from the conserved Adda amino acid for structural confirmation. The method was used to extract six MCs (MC-LR, MC-RR, MC-YR, MC-LA, MC-LF, and MC-LW) from spiked liver tissue and the MC-LR cysteine adduct (MC-LR-Cys) created by the glutathione detoxification pathway. Matrix-matched internal standard calibration curves were constructed for each MC (R2 ≥ 0.993), with LOQs between 0.25 ng per g of liver tissue (ng/g) and 0.75 ng/g for MC-LR, MC-RR, MC-YR, MC-LA, and MC-LR-Cys, and 2.5 ng/g for MC-LF and MC-LW. The protocol was applied to extract and quantify MC-LR and MC-LR-Cys from the liver of mice that had been gavaged with 50 µg or 100 µg of MC-LR per kg bodyweight and were euthanized 2 h, 4 h, or 48 h after final gavage. C57Bl/6J (wild type, control) and Leprdb/J (experiment) mice were used as a model to study non-alcoholic fatty liver disease. The Leprdb/J mice were relatively inefficient in metabolizing MC-LR into MC-LR-Cys, which is an important defense mechanism against MC-LR exposure. Trends were also observed as a function of MC-LR gavage amount and time between final MC-LR gavage and euthanasia/organ harvest.

ACS Style

David Baliu-Rodriguez; Daria Kucheriavaia; Dilrukshika S. W. Palagama; Apurva Lad; Grace M. O’Neill; Johnna A. Birbeck; David J. Kennedy; Steven T. Haller; Judy A. Westrick; Dragan Isailovic. Development and Application of Extraction Methods for LC-MS Quantification of Microcystins in Liver Tissue. Toxins 2020, 12, 263 .

AMA Style

David Baliu-Rodriguez, Daria Kucheriavaia, Dilrukshika S. W. Palagama, Apurva Lad, Grace M. O’Neill, Johnna A. Birbeck, David J. Kennedy, Steven T. Haller, Judy A. Westrick, Dragan Isailovic. Development and Application of Extraction Methods for LC-MS Quantification of Microcystins in Liver Tissue. Toxins. 2020; 12 (4):263.

Chicago/Turabian Style

David Baliu-Rodriguez; Daria Kucheriavaia; Dilrukshika S. W. Palagama; Apurva Lad; Grace M. O’Neill; Johnna A. Birbeck; David J. Kennedy; Steven T. Haller; Judy A. Westrick; Dragan Isailovic. 2020. "Development and Application of Extraction Methods for LC-MS Quantification of Microcystins in Liver Tissue." Toxins 12, no. 4: 263.

Journal article
Published: 05 February 2020 in Journal of Great Lakes Research
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Liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MS/MS) were used to provide qualitative and quantitative information about microcystin (MC) congeners in western Lake Erie. Samples were collected at eight open-water locations on selected days during harmful algal blooms (HABs) in 2016 and 2017. Seven MCs were identified and 20 MCs were tentatively identified using high-resolution mass accuracies and a unique fragment (Adda m/z 135). The most abundant MC was MC-LR, followed by MC-RR, MC-YR, and MC-LA, and these congeners were quantified. Total (extracellular and intracellular) MC concentrations ranged from 0.068 to 14.88 µg/L in 2016, and from 0.050 to 10.15 µg/L in 2017, with averages of 2.71 and 1.86 µg/L, respectively. Near-shore sites in Lake Erie had higher MC concentrations and Microcystis biovolumes than off-shore sites. This implies that nutrient loading from the Maumee River greatly influences Maumee Bay, and this influence decreases with distance from the river. Consequently, six MCs (MC-LR, MC-RR, MC-LA, MC-YR, MC-LW, and MC-LF) were quantified in water samples collected from the Maumee River and the Maumee Bay shore of Lake Erie in 2017, and MC-RR was the most abundant. The total MC concentrations in river samples ranged from 0.17 to 305.03 µg/L. Additionally, an MC degradation product (linear MC-LR) was detected at all open-water locations, and data indicated an increase in its concentration towards the end of the bloom. The trends for 2016 and 2017 HABs are comparable in terms of spatial distribution and MC congeners produced, though the intensity and peak dates change.

ACS Style

Dilrukshika S.W. Palagama; David Baliu-Rodriguez; Brenda K. Snyder; Jennifer A. Thornburg; Thomas B. Bridgeman; Dragan Isailovic. Identification and quantification of microcystins in western Lake Erie during 2016 and 2017 harmful algal blooms. Journal of Great Lakes Research 2020, 46, 289 -301.

AMA Style

Dilrukshika S.W. Palagama, David Baliu-Rodriguez, Brenda K. Snyder, Jennifer A. Thornburg, Thomas B. Bridgeman, Dragan Isailovic. Identification and quantification of microcystins in western Lake Erie during 2016 and 2017 harmful algal blooms. Journal of Great Lakes Research. 2020; 46 (2):289-301.

Chicago/Turabian Style

Dilrukshika S.W. Palagama; David Baliu-Rodriguez; Brenda K. Snyder; Jennifer A. Thornburg; Thomas B. Bridgeman; Dragan Isailovic. 2020. "Identification and quantification of microcystins in western Lake Erie during 2016 and 2017 harmful algal blooms." Journal of Great Lakes Research 46, no. 2: 289-301.

Journal article
Published: 23 August 2019 in Toxins
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Microcystins are potent hepatotoxins that have become a global health concern in recent years. Their actions in at-risk populations with pre-existing liver disease is unknown. We tested the hypothesis that the No Observed Adverse Effect Level (NOAEL) of Microcystin-LR (MC-LR) established in healthy mice would cause exacerbation of hepatic injury in a murine model (Leprdb/J) of Non-alcoholic Fatty Liver Disease (NAFLD). Ten-week-old male Leprdb/J mice were gavaged with 50 μg/kg, 100 μg/kg MC-LR or vehicle every 48 h for 4 weeks (n = 15–17 mice/group). Early mortality was observed in both the 50 μg/kg (1/17, 6%), and 100 μg/kg (3/17, 18%) MC-LR exposed mice. MC-LR exposure resulted in significant increases in circulating alkaline phosphatase levels, and histopathological markers of hepatic injury as well as significant upregulation of genes associated with hepatotoxicity, necrosis, nongenotoxic hepatocarcinogenicity and oxidative stress response. In addition, we observed exposure dependent changes in protein phosphorylation sites in pathways involved in inflammation, immune function, and response to oxidative stress. These results demonstrate that exposure to MC-LR at levels that are below the NOAEL established in healthy animals results in significant exacerbation of hepatic injury that is accompanied by genetic and phosphoproteomic dysregulation in key signaling pathways in the livers of NAFLD mice.

ACS Style

Apurva Lad; Robin C. Su; Joshua D. Breidenbach; Paul M. Stemmer; Nicholas J. Carruthers; Nayeli K. Sanchez; Fatimah K. Khalaf; Shungang Zhang; Andrew L. Kleinhenz; Prabhatchandra Dube; Chrysan J. Mohammed; Judy A. Westrick; Erin L. Crawford; Dilrukshika Palagama; David Baliu-Rodriguez; Dragan Isailovic; Bruce Levison; Nikolai Modyanov; Amira F. Gohara; Deepak Malhotra; Steven T. Haller; David J. Kennedy. Chronic Low Dose Oral Exposure to Microcystin-LR Exacerbates Hepatic Injury in a Murine Model of Non-Alcoholic Fatty Liver Disease. Toxins 2019, 11, 486 .

AMA Style

Apurva Lad, Robin C. Su, Joshua D. Breidenbach, Paul M. Stemmer, Nicholas J. Carruthers, Nayeli K. Sanchez, Fatimah K. Khalaf, Shungang Zhang, Andrew L. Kleinhenz, Prabhatchandra Dube, Chrysan J. Mohammed, Judy A. Westrick, Erin L. Crawford, Dilrukshika Palagama, David Baliu-Rodriguez, Dragan Isailovic, Bruce Levison, Nikolai Modyanov, Amira F. Gohara, Deepak Malhotra, Steven T. Haller, David J. Kennedy. Chronic Low Dose Oral Exposure to Microcystin-LR Exacerbates Hepatic Injury in a Murine Model of Non-Alcoholic Fatty Liver Disease. Toxins. 2019; 11 (9):486.

Chicago/Turabian Style

Apurva Lad; Robin C. Su; Joshua D. Breidenbach; Paul M. Stemmer; Nicholas J. Carruthers; Nayeli K. Sanchez; Fatimah K. Khalaf; Shungang Zhang; Andrew L. Kleinhenz; Prabhatchandra Dube; Chrysan J. Mohammed; Judy A. Westrick; Erin L. Crawford; Dilrukshika Palagama; David Baliu-Rodriguez; Dragan Isailovic; Bruce Levison; Nikolai Modyanov; Amira F. Gohara; Deepak Malhotra; Steven T. Haller; David J. Kennedy. 2019. "Chronic Low Dose Oral Exposure to Microcystin-LR Exacerbates Hepatic Injury in a Murine Model of Non-Alcoholic Fatty Liver Disease." Toxins 11, no. 9: 486.

Journal article
Published: 05 February 2019 in Science of The Total Environment
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Microcystins (MCs) appear during harmful algal blooms (HABs) in water sources worldwide, and represent a threat for humans and animals ingesting or inhaling MCs from the environment. Herein, treated rice husk (RH) was tested as a recyclable sorbent for removal of six MCs (MC-RR, MC-LR, MC-YR, MC-LA, MC-LF, and MC-LW) from water. RH was refluxed with hydrochloric acid and heated to 250 °C to produce the sorbent material. Twenty milligrams of treated RH removed >95% of the MCs from a 30 mL solution containing 25 μg/L of each MC. The adsorption of MCs onto RH follows the Freundlich isotherm model (R2 ≥ 0.9612) and pseudo-second-order kinetics (R2 ≥ 0.9996). More than 90% of MCs were removed within 5 min, and >95% were removed at equilibrium (in <40 min). Performance of the RH sorbent was evaluated by removing MCs from Lake Erie water collected during an algal bloom in 2017. The total concentration (extracellular plus intracellular) of six tested MCs in lake water ranged from 3.7 to 13,606 μg/L, and removal of MCs by treated RH ranged from 100.0% to 71.8%, respectively. The removal capacity of RH for the six MCs from the lake water sample containing 13,606 μg/L of MCs was 586 μg per g of treated RH. After being used to extract MCs, the RH was heated to 560 °C to produce silica nanoparticles. Therefore, treated RH enables rapid and efficient removal of MCs from water and it can be recycled for use as a raw material. Overall, treated RH can contribute to mitigation of environmental and health effects caused by MCs and reduce concerns for toxic waste disposal.

ACS Style

Dilrukshika S.W. Palagama; Amila M. Devasurendra; David Baliu-Rodriguez; Jon R. Kirchhoff; Dragan Isailovic. Treated rice husk as a recyclable sorbent for the removal of microcystins from water. Science of The Total Environment 2019, 666, 1292 -1300.

AMA Style

Dilrukshika S.W. Palagama, Amila M. Devasurendra, David Baliu-Rodriguez, Jon R. Kirchhoff, Dragan Isailovic. Treated rice husk as a recyclable sorbent for the removal of microcystins from water. Science of The Total Environment. 2019; 666 ():1292-1300.

Chicago/Turabian Style

Dilrukshika S.W. Palagama; Amila M. Devasurendra; David Baliu-Rodriguez; Jon R. Kirchhoff; Dragan Isailovic. 2019. "Treated rice husk as a recyclable sorbent for the removal of microcystins from water." Science of The Total Environment 666, no. : 1292-1300.

Journal article
Published: 17 August 2018 in Journal of Chromatography A
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The protocols for solid-phase extraction (SPE) of six microcystins (MCs; MC-LR, MC-RR, MC-LA, MC-LF, MC-LW, and MC-YR) from mouse urine, mouse plasma, and human serum are reported. The quantification of those MCs in biofluids was achieved using HPLC-orbitrap-MS in selected-ion monitoring (SIM) mode, and MCs in urine samples were also quantified by ultra-HPLC-triple quadrupole-tandem mass spectrometry (UHPLC-QqQ-MS/MS) in multiple reaction monitoring (MRM) mode. Under optimal conditions, the extraction recoveries of MCs from samples spiked at two different concentrations (1 μg/L and 10 μg/L) ranged from 90.4% to 104.3% with relative standard deviations (RSDs) ≤ 4.7% for mouse urine, 90.4-106.9% with RSDs ≤ 6.3% for mouse plasma, and 90.0-104.8% with RSDs ≤ 5.0% for human serum. Matrix-matched internal standard calibration curves were linear with R2 ≥ 0.9950 for MC-LR, MC-RR and MC-YR, and R2 ≥ 0.9883 for MC-LA, MC-LF, and MC-LW. The limits of quantification (LOQs) in spiked urine samples were ~0.13 µg/L for MC-LR, MC-RR, and MC-YR, and ~0.50 µg/L for MC-LA, MC-LF, and MC-LW, while the LOQs in spiked plasma and serum were ~0.25 µg/L for MC-LR, MC-RR, and MC-YR, and ~1.00 µg/L for MC-LA, MC-LF, and MC-LW. The developed methods were applied in a proof-of-concept study to quantify urinary and blood concentrations of MC-LR after oral administration to mice. The urine of mice administered 50 μg of MC-LR per kg bodyweight contained on average 1.30 μg/L of MC-LR (n = 8), while mice administered 100 μg of MC-LR per kg bodyweight had average MC-LR concentration of 2.82 μg/L (n = 8). MC-LR was also quantified in the plasma of the same mice. The results showed that increased MC-LR dosage led to larger urinary and plasma MC-LR concentrations and the developed methods were effective for the quantification of MCs in mouse biofluids.

ACS Style

Dilrukshika S.W. Palagama; David Baliu-Rodriguez; Apurva Lad; Bruce S. Levison; David J. Kennedy; Steven T. Haller; Judy Westrick; Kenneth Hensley; Dragan Isailovic. Development and applications of solid-phase extraction and liquid chromatography-mass spectrometry methods for quantification of microcystins in urine, plasma, and serum. Journal of Chromatography A 2018, 1573, 66 -77.

AMA Style

Dilrukshika S.W. Palagama, David Baliu-Rodriguez, Apurva Lad, Bruce S. Levison, David J. Kennedy, Steven T. Haller, Judy Westrick, Kenneth Hensley, Dragan Isailovic. Development and applications of solid-phase extraction and liquid chromatography-mass spectrometry methods for quantification of microcystins in urine, plasma, and serum. Journal of Chromatography A. 2018; 1573 ():66-77.

Chicago/Turabian Style

Dilrukshika S.W. Palagama; David Baliu-Rodriguez; Apurva Lad; Bruce S. Levison; David J. Kennedy; Steven T. Haller; Judy Westrick; Kenneth Hensley; Dragan Isailovic. 2018. "Development and applications of solid-phase extraction and liquid chromatography-mass spectrometry methods for quantification of microcystins in urine, plasma, and serum." Journal of Chromatography A 1573, no. : 66-77.

Journal article
Published: 13 April 2018 in Journal of Chromatography A
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A novel sorbent material, gold-polypyrrole (Au-PPy) nanocomposite-coated silica, is described for the efficient solid-phase extraction (SPE) of six common microcystins (MCs) well below the recommended United States EPA and World Health Organization (WHO) guidelines. With the optimized SPE protocol, samples spiked with MCs were determined at ng/L concentrations by liquid chromatography-mass spectrometry (LC–MS) in different aqueous sample matrices, including HPLC-grade, tap, and lake water. The average recoveries for all MCs tested in the three water matrices ranged from 94.1–103.2% with relative standard deviations (RSDs) of 1.6–5.4%, which indicated excellent extraction efficiency and reproducibility. Limits of detection (LODs) and limits of quantification (LOQs) for all MCs in both tap and lake water samples were determined to be ≤1.5 ng/L and 5.0 ng/L, respectively. The Au-PPy nanocomposite-coated sorbent material was reusable for at least three independent MC extractions with a single SPE cartridge in the concentration range of 10–500 ng/L. Importantly, off-column selective separation at the sample preparation and preconcentration stage between more hydrophilic and more hydrophobic MCs was achieved by sequential elution through changes in the solvent composition and SPE bed size. Therefore, the Au-PPy nanocomposite-coated silica sorbent is a promising new material for the quantification of MC variants in water samples.

ACS Style

Amila M. Devasurendra; Dilrukshika S.W. Palagama; Ahmad Rohanifar; Dragan Isailovic; Jon R. Kirchhoff; Jared L. Anderson. Solid-phase extraction, quantification, and selective determination of microcystins in water with a gold-polypyrrole nanocomposite sorbent material. Journal of Chromatography A 2018, 1560, 1 -9.

AMA Style

Amila M. Devasurendra, Dilrukshika S.W. Palagama, Ahmad Rohanifar, Dragan Isailovic, Jon R. Kirchhoff, Jared L. Anderson. Solid-phase extraction, quantification, and selective determination of microcystins in water with a gold-polypyrrole nanocomposite sorbent material. Journal of Chromatography A. 2018; 1560 ():1-9.

Chicago/Turabian Style

Amila M. Devasurendra; Dilrukshika S.W. Palagama; Ahmad Rohanifar; Dragan Isailovic; Jon R. Kirchhoff; Jared L. Anderson. 2018. "Solid-phase extraction, quantification, and selective determination of microcystins in water with a gold-polypyrrole nanocomposite sorbent material." Journal of Chromatography A 1560, no. : 1-9.

Journal article
Published: 01 November 2017 in International Journal of Mass Spectrometry
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ACS Style

Krishani K. Rajanayake; Kevin Markus; Dragan Isailovic. Determination of the origin of doubly-cationized monosialylated fragments in MS/MS spectra of singly-cationized LSTb and GM1 using ion mobility spectrometry-mass spectrometry. International Journal of Mass Spectrometry 2017, 422, 1 -12.

AMA Style

Krishani K. Rajanayake, Kevin Markus, Dragan Isailovic. Determination of the origin of doubly-cationized monosialylated fragments in MS/MS spectra of singly-cationized LSTb and GM1 using ion mobility spectrometry-mass spectrometry. International Journal of Mass Spectrometry. 2017; 422 ():1-12.

Chicago/Turabian Style

Krishani K. Rajanayake; Kevin Markus; Dragan Isailovic. 2017. "Determination of the origin of doubly-cationized monosialylated fragments in MS/MS spectra of singly-cationized LSTb and GM1 using ion mobility spectrometry-mass spectrometry." International Journal of Mass Spectrometry 422, no. : 1-12.

Journals
Published: 13 February 2017 in Analytical Methods
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A solid-phase extraction (SPE) protocol was developed and combined with HPLC-ESI-MS for the quantification of common cyanobacterial toxins, microcystins (MCs), in water.

ACS Style

Dilrukshika S. W. Palagama; Raymond E. West Iii; Dragan Isailovic. Improved solid-phase extraction protocol and sensitive quantification of six microcystins in water using an HPLC-orbitrap mass spectrometry system. Analytical Methods 2017, 9, 2021 -2030.

AMA Style

Dilrukshika S. W. Palagama, Raymond E. West Iii, Dragan Isailovic. Improved solid-phase extraction protocol and sensitive quantification of six microcystins in water using an HPLC-orbitrap mass spectrometry system. Analytical Methods. 2017; 9 (13):2021-2030.

Chicago/Turabian Style

Dilrukshika S. W. Palagama; Raymond E. West Iii; Dragan Isailovic. 2017. "Improved solid-phase extraction protocol and sensitive quantification of six microcystins in water using an HPLC-orbitrap mass spectrometry system." Analytical Methods 9, no. 13: 2021-2030.

Research article
Published: 25 January 2017 in Biomarkers
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Quantitative changes of salivary proteins due to acute stress were detected. To explore protein markers of stress in saliva of eight medical residents who performed emergency medicine simulations. Saliva was collected before the simulations, after the simulations, and following morning upon waking. Proteins were separated by SDS-PAGE, identified by MS, and relatively quantified by densitometry. Salivary alpha-amylase and S–type cystatins significantly increased, while the ~26 kDa and low-molecular weight (<10 kDa) SDS-PAGE bands exhibited changes after stress. Alpha-amylase and cystatins are potential salivary markers of acute stress, but further validation should be performed using larger sample populations.

ACS Style

Rachel K. Marvin; Muncharie B. Saepoo; Simiao Ye; Donald B. White; Rong Liu; Kenneth Hensley; Paul Rega; Viviane Kazan; David R. Giovannucci; Dragan Isailovic. Salivary protein changes in response to acute stress in medical residents performing advanced clinical simulations: a pilot proteomics study. Biomarkers 2017, 22, 372 -382.

AMA Style

Rachel K. Marvin, Muncharie B. Saepoo, Simiao Ye, Donald B. White, Rong Liu, Kenneth Hensley, Paul Rega, Viviane Kazan, David R. Giovannucci, Dragan Isailovic. Salivary protein changes in response to acute stress in medical residents performing advanced clinical simulations: a pilot proteomics study. Biomarkers. 2017; 22 (3-4):372-382.

Chicago/Turabian Style

Rachel K. Marvin; Muncharie B. Saepoo; Simiao Ye; Donald B. White; Rong Liu; Kenneth Hensley; Paul Rega; Viviane Kazan; David R. Giovannucci; Dragan Isailovic. 2017. "Salivary protein changes in response to acute stress in medical residents performing advanced clinical simulations: a pilot proteomics study." Biomarkers 22, no. 3-4: 372-382.

Comparative study
Published: 01 August 2016 in Carbohydrate Research
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Glycosphingolipids (GSLs) are important biomolecules, which are linked to many diseases such as GSL storage disorders and cancer. Consequently, the expression of GSLs may be altered in ovarian cancer cell lines in comparison to apparently healthy cell lines. Here, differential expressions of GSLs in an epithelial ovarian cancer cell line SKOV3 and a nontumorigenic epithelial ovarian cell line T29 were studied using matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and MALDI-MS/MS. The isolation of GSLs from SKOV3 and T29 cell lines was carried out using Folch partition. GSLs were successfully detected by MALDI-MS, and structurally assigned by a comparison of their MALDI-MS/MS fragmentation patterns with MS/MS data found in SimLipid database. Additionally, LIPID MAPS was used to assign GSL ion masses in MALDI-MS spectra. Seventeen neutral GSLs were identified in Folch partition lower (chloroform/methanol) phases originating from both cell lines, while five globo series neutral GSLs were identified only in the Folch partition lower phase of SKOV3 cell line. Several different sialylated GSLs were detected in Folch partition upper (water/methanol) phases of SKOV3 and T29 cell lines. Overall, this study demonstrates the alteration and increased glycosylation of GSLs in an epithelial ovarian cancer cell line in comparison to a nontumorigenic epithelial ovarian cell line.

ACS Style

Krishani K. Rajanayake; William R. Taylor; Dragan Isailovic. The comparison of glycosphingolipids isolated from an epithelial ovarian cancer cell line and a nontumorigenic epithelial ovarian cell line using MALDI-MS and MALDI-MS/MS. Carbohydrate Research 2016, 431, 6 -14.

AMA Style

Krishani K. Rajanayake, William R. Taylor, Dragan Isailovic. The comparison of glycosphingolipids isolated from an epithelial ovarian cancer cell line and a nontumorigenic epithelial ovarian cell line using MALDI-MS and MALDI-MS/MS. Carbohydrate Research. 2016; 431 ():6-14.

Chicago/Turabian Style

Krishani K. Rajanayake; William R. Taylor; Dragan Isailovic. 2016. "The comparison of glycosphingolipids isolated from an epithelial ovarian cancer cell line and a nontumorigenic epithelial ovarian cell line using MALDI-MS and MALDI-MS/MS." Carbohydrate Research 431, no. : 6-14.

Journal article
Published: 01 November 2014 in International Journal of Mass Spectrometry
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ACS Style

Raymond E. West; Rachel K. Marvin; Kenneth Hensley; Dragan Isailovic. Qualitative analysis of omega-3 fatty acid oxidation by desorption electrospray ionization-mass spectrometry (DESI-MS). International Journal of Mass Spectrometry 2014, 372, 29 -38.

AMA Style

Raymond E. West, Rachel K. Marvin, Kenneth Hensley, Dragan Isailovic. Qualitative analysis of omega-3 fatty acid oxidation by desorption electrospray ionization-mass spectrometry (DESI-MS). International Journal of Mass Spectrometry. 2014; 372 ():29-38.

Chicago/Turabian Style

Raymond E. West; Rachel K. Marvin; Kenneth Hensley; Dragan Isailovic. 2014. "Qualitative analysis of omega-3 fatty acid oxidation by desorption electrospray ionization-mass spectrometry (DESI-MS)." International Journal of Mass Spectrometry 372, no. : 29-38.

Journal article
Published: 01 November 2013 in International Journal of Mass Spectrometry
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ACS Style

Raymond E. West; Eric W. Findsen; Dragan Isailovic. Fluorophore-assisted laser desorption/ionization-mass spectrometry (FALDI-MS). International Journal of Mass Spectrometry 2013, 353, 54 -59.

AMA Style

Raymond E. West, Eric W. Findsen, Dragan Isailovic. Fluorophore-assisted laser desorption/ionization-mass spectrometry (FALDI-MS). International Journal of Mass Spectrometry. 2013; 353 ():54-59.

Chicago/Turabian Style

Raymond E. West; Eric W. Findsen; Dragan Isailovic. 2013. "Fluorophore-assisted laser desorption/ionization-mass spectrometry (FALDI-MS)." International Journal of Mass Spectrometry 353, no. : 54-59.

Journal article
Published: 27 July 2013 in Journal of the American Society for Mass Spectrometry
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We report the development of a new AP visible-wavelength MALDI-ion trap-MS instrument with significantly improved performance over our previously reported system (Int. J. Mass Spectrom. 315, 66-73 (2012)). A Nd:YAG pulsed laser emitting light at 532 nm was used to desorb and ionize oligosaccharides and peptides in transmission geometry through a glass slide. Limits of detection (LODs) achieved in MS mode correspond to picomole quantities of oligosaccharides and femtomole quantities of peptides. Tandem MS (MS/MS) experiments enabled identification of enzymatically digested proteins and oligosaccharides by comparison of MS/MS spectra with data found in protein and glycan databases. Moreover, the softness of ionization, LODs, and fragmentation spectra of biomolecules by AP visible-wavelength MALDI-MS were compared to those obtained by AP UV MALDI-MS using a Nd:YAG laser emitting light at 355 nm. AP visible-wavelength MALDI appears to be a softer ionization technique then AP UV MALDI for the analysis of sulfated peptides, while visible-wavelength MALDI-MS, MS/MS, and MS/MS/MS spectra of other biomolecules analyzed were mostly similar to those obtained by AP UV MALDI-MS. Therefore, the methodology presented will be useful for MS and MS(n) analyses of biomolecules at atmospheric pressure. Additionally, the AP visible-wavelength MALDI developed can be readily used for soft ionization of analytes on various mass spectrometers.

ACS Style

Raymond E. West; Eric W. Findsen; Dragan Isailovic; Raymond E. West Iii. Analysis of Biomolecules by Atmospheric Pressure Visible-Wavelength MALDI-Ion Trap-MS in Transmission Geometry. Journal of the American Society for Mass Spectrometry 2013, 24, 1467 -1476.

AMA Style

Raymond E. West, Eric W. Findsen, Dragan Isailovic, Raymond E. West Iii. Analysis of Biomolecules by Atmospheric Pressure Visible-Wavelength MALDI-Ion Trap-MS in Transmission Geometry. Journal of the American Society for Mass Spectrometry. 2013; 24 (10):1467-1476.

Chicago/Turabian Style

Raymond E. West; Eric W. Findsen; Dragan Isailovic; Raymond E. West Iii. 2013. "Analysis of Biomolecules by Atmospheric Pressure Visible-Wavelength MALDI-Ion Trap-MS in Transmission Geometry." Journal of the American Society for Mass Spectrometry 24, no. 10: 1467-1476.

Journal article
Published: 01 August 2012 in Journal of Chromatography B
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Due to relatively low reproducibility of the ionization and differences when using buffers as mobile phases, the quantitative analysis by electrospray ionization mass spectrometry (ESI-MS) can be often challenging. In the present study, the native fluorescence of phenylalanine, tyrosine, and tryptophan was investigated as an improvement tool for the analytical quantification of peptides and proteins by HPLC-ESI-MS. Natively fluorescent amino acids as well as peptides, proteins, and protein digests were successfully separated by HPLC, and quantified with a spectrofluorimetric detector and ESI-MS. The two detectors were connected in series and enabled the sequential measurements of the fluorescence intensities as well as the measurements of the ion signals and mass spectral characterization of separated polypeptides. Fluorescence detector provided better linearity and repeatability of quantification than mass spectrometer, and similar limits of detection for most of biomolecules analyzed. The fluorescence signal was linear over 3-4 orders of magnitude with limits of detection in picomole or high femtomole range, depending on nature and number of natively fluorescent amino acid residues present in the analyzed polypeptides. Hence, native fluorescence of phenylalanine, tyrosine, and tryptophan can be used as a label-free methodology to facilitate quantification of peptides and proteins by LC-ESI-MS.

ACS Style

Suraj Saraswat; Bruce Snyder; Dragan Isailovic. Quantification of HPLC-separated peptides and proteins by spectrofluorimetric detection of native fluorescence and mass spectrometry. Journal of Chromatography B 2012, 902, 70 -77.

AMA Style

Suraj Saraswat, Bruce Snyder, Dragan Isailovic. Quantification of HPLC-separated peptides and proteins by spectrofluorimetric detection of native fluorescence and mass spectrometry. Journal of Chromatography B. 2012; 902 ():70-77.

Chicago/Turabian Style

Suraj Saraswat; Bruce Snyder; Dragan Isailovic. 2012. "Quantification of HPLC-separated peptides and proteins by spectrofluorimetric detection of native fluorescence and mass spectrometry." Journal of Chromatography B 902, no. : 70-77.

Journal article
Published: 01 April 2012 in International Journal of Mass Spectrometry
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An atmospheric pressure (AP) visible-wavelength MALDI source was developed and coupled to a quadrupole time-of-flight (Q-TOF) mass spectrometer. This instrument employed a pulsed laser emitting light at a wavelength of 532 nm to desorb and ionize samples such as dyes, oligosaccharides, peptides, and synthetic polymers at atmospheric pressure. Ions formed were analyzed by the Q-TOF in both MS and tandem MS (MS/MS) modes. Several visible-wavelength absorbing dyes were successfully utilized and studied as matrices. Among these dyes, nuclear fast red (NFR), rhodamine B isothiocyanate (RITC), and 5(6)-carboxytetramethyl-rhodamine N-succinimidyl ester (TAMRA, SE) are reported as effective visible-wavelength MALDI-MS matrices for the first time. This report demonstrates applicability of visible-wavelength AP MALDI-MS and AP MALDI MS/MS to the detection and structural analysis of dye molecules, biomolecules, and synthetic polymers.

ACS Style

Zhen Sun; Eric W. Findsen; Dragan Isailovic. Atmospheric pressure visible-wavelength MALDI-MS. International Journal of Mass Spectrometry 2012, 315, 66 -73.

AMA Style

Zhen Sun, Eric W. Findsen, Dragan Isailovic. Atmospheric pressure visible-wavelength MALDI-MS. International Journal of Mass Spectrometry. 2012; 315 ():66-73.

Chicago/Turabian Style

Zhen Sun; Eric W. Findsen; Dragan Isailovic. 2012. "Atmospheric pressure visible-wavelength MALDI-MS." International Journal of Mass Spectrometry 315, no. : 66-73.

Research article
Published: 26 January 2012 in Journal of Proteome Research
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The folate binding protein (FBP), also known as the folate receptor (FR), is a glycoprotein which binds the vitamin folic acid and its analogues. FBP contains multiple N-glycosilation sites, is selectively expressed in tissues and body fluids, and mediates targeted therapies in cancer and inflammatory diseases. Much remains to be understood about the structure, composition, and the tissue specificities of N-glycans bound to FBP. Here, we performed structural characterization of N-linked glycans originating from bovine and human milk FBPs. The N-linked glycans were enzymatically released from FBPs, purified, and permethylated. Native and permethylated glycans were further analyzed by matrix-assisted laser desorption/ionization (MALDI) and electrospray ionization (ESI) mass spectrometry (MS), while tandem MS (MS/MS) was used for their structural characterization. The assignment of putative glycan structures from MS and MS/MS data was achieved using Functional Glycomics glycan database and SimGlycan software, respectively. It was found that FBP from human milk contains putative structures that have composition consistent with high-mannose (Hex5–6HexNAc2) as well as hybrid and complex N-linked glycans (NeuAc0–1Fuc0–3Hex3–6HexNAc3–5). The FBP from bovine milk contains putative structures corresponding to high-mannose (Hex4–9HexNAc2) as well as hybrid and complex N-linked glycans (Hex3–6HexNAc3–6), but these glycans mostly do not contain fucose and sialic acid. Glycomic characterization of FBP provides valuable insight into the structure of this pharmacologically important glycoprotein and may have utility in tissue-selective drug targeting and as a biomarker.

ACS Style

Nidhi Jaiswal; Suraj Saraswat; Manohar Ratnam; Dragan Isailovic. Analysis of Folate Binding Protein N-linked Glycans by Mass Spectrometry. Journal of Proteome Research 2012, 11, 1551 -1560.

AMA Style

Nidhi Jaiswal, Suraj Saraswat, Manohar Ratnam, Dragan Isailovic. Analysis of Folate Binding Protein N-linked Glycans by Mass Spectrometry. Journal of Proteome Research. 2012; 11 (3):1551-1560.

Chicago/Turabian Style

Nidhi Jaiswal; Suraj Saraswat; Manohar Ratnam; Dragan Isailovic. 2012. "Analysis of Folate Binding Protein N-linked Glycans by Mass Spectrometry." Journal of Proteome Research 11, no. 3: 1551-1560.

Journal article
Published: 12 August 2011 in The Journal of Physical Chemistry C
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ACS Style

Suraj Saraswat; Anil Desireddy; Desheng Zheng; Lijun Guo; H. Peter Lu; Terry P. Bigioni; Dragan Isailovic. Energy Transfer from Fluorescent Proteins to Metal Nanoparticles. The Journal of Physical Chemistry C 2011, 115, 17587 -17593.

AMA Style

Suraj Saraswat, Anil Desireddy, Desheng Zheng, Lijun Guo, H. Peter Lu, Terry P. Bigioni, Dragan Isailovic. Energy Transfer from Fluorescent Proteins to Metal Nanoparticles. The Journal of Physical Chemistry C. 2011; 115 (35):17587-17593.

Chicago/Turabian Style

Suraj Saraswat; Anil Desireddy; Desheng Zheng; Lijun Guo; H. Peter Lu; Terry P. Bigioni; Dragan Isailovic. 2011. "Energy Transfer from Fluorescent Proteins to Metal Nanoparticles." The Journal of Physical Chemistry C 115, no. 35: 17587-17593.

Research article
Published: 01 June 2011 in Applied Spectroscopy
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A multimodal methodology for spectral imaging of cells is presented. The spectral imaging setup uses a transmission diffraction grating on a light microscope to concurrently record spectral images of cells and cellular organelles by fluorescence, darkfield, brightfield, and differential interference contrast (DIC) spectral microscopy. Initially, the setup was applied for fluorescence spectral imaging of yeast and mammalian cells labeled with multiple fluorophores. Fluorescence signals originating from fluorescently labeled biomolecules in cells were collected through triple or single filter cubes, separated by the grating, and imaged using a charge-coupled device (CCD) camera. Cellular components such as nuclei, cytoskeleton, and mitochondria were spatially separated by the fluorescence spectra of the fluorophores present in them, providing detailed multi-colored spectral images of cells. Additionally, the grating-based spectral microscope enabled measurement of scattering and absorption spectra of unlabeled cells and stained tissue sections using darkfield and brightfield or DIC spectral microscopy, respectively. The presented spectral imaging methodology provides a readily affordable approach for multimodal spectral characterization of biological cells and other specimens.

ACS Style

Dragan Isailovic; Yang Xu; Tyler Copus; Suraj Saraswat; Surya M. Nauli. Multimodal Spectral Imaging of Cells Using a Transmission Diffraction Grating on a Light Microscope. Applied Spectroscopy 2011, 65, 575 -583.

AMA Style

Dragan Isailovic, Yang Xu, Tyler Copus, Suraj Saraswat, Surya M. Nauli. Multimodal Spectral Imaging of Cells Using a Transmission Diffraction Grating on a Light Microscope. Applied Spectroscopy. 2011; 65 (6):575-583.

Chicago/Turabian Style

Dragan Isailovic; Yang Xu; Tyler Copus; Suraj Saraswat; Surya M. Nauli. 2011. "Multimodal Spectral Imaging of Cells Using a Transmission Diffraction Grating on a Light Microscope." Applied Spectroscopy 65, no. 6: 575-583.

Journal article
Published: 01 January 2011 in Journal of Biomedical Science
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A derived peptide from activity-dependent neurotrophic factor (ADNF-9) has been shown to be neuroprotective in the fetal alcohol exposure model. We investigated the neuroprotective effects of ADNF-9 against alcohol-induced apoptosis using TUNEL staining. We further characterize in this study the proteomic architecture underlying the role of ADNF-9 against ethanol teratogenesis during early fetal brain development using liquid chromatography in conjunction with tandem mass spectrometry (LC-MS/MS).

ACS Style

Youssef Sari; Zaneer M Segu; Ahmed YoussefAgha; Jonathan A Karty; Dragan Isailovic. Neuroprotective peptide ADNF-9 in fetal brain of C57BL/6 mice exposed prenatally to alcohol. Journal of Biomedical Science 2011, 18, 77 -77.

AMA Style

Youssef Sari, Zaneer M Segu, Ahmed YoussefAgha, Jonathan A Karty, Dragan Isailovic. Neuroprotective peptide ADNF-9 in fetal brain of C57BL/6 mice exposed prenatally to alcohol. Journal of Biomedical Science. 2011; 18 (1):77-77.

Chicago/Turabian Style

Youssef Sari; Zaneer M Segu; Ahmed YoussefAgha; Jonathan A Karty; Dragan Isailovic. 2011. "Neuroprotective peptide ADNF-9 in fetal brain of C57BL/6 mice exposed prenatally to alcohol." Journal of Biomedical Science 18, no. 1: 77-77.