Displaying publications 1 - 20 of 82 in total

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  1. Li CMY, Briggs MT, Lee YR, Tin T, Young C, Pierides J, et al.
    Clin Exp Med, 2024 Mar 16;24(1):53.
    PMID: 38492056 DOI: 10.1007/s10238-024-01311-5
    Colorectal cancer (CRC) is the second leading cause of cancer-related deaths worldwide. CRC liver metastases (CRLM) are often resistant to conventional treatments, with high rates of recurrence. Therefore, it is crucial to identify biomarkers for CRLM patients that predict cancer progression. This study utilised matrix-assisted laser desorption/ionisation mass spectrometry imaging (MALDI-MSI) in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) to spatially map the CRLM tumour proteome. CRLM tissue microarrays (TMAs) of 84 patients were analysed using tryptic peptide MALDI-MSI to spatially monitor peptide abundances across CRLM tissues. Abundance of peptides was compared between tumour vs stroma, male vs female and across three groups of patients based on overall survival (0-3 years, 4-6 years, and 7+ years). Peptides were then characterised and matched using LC-MS/MS. A total of 471 potential peptides were identified by MALDI-MSI. Our results show that two unidentified m/z values (1589.876 and 1092.727) had significantly higher intensities in tumours compared to stroma. Ten m/z values were identified to have correlation with biological sex. Survival analysis identified three peptides (Histone H4, Haemoglobin subunit alpha, and Inosine-5'-monophosphate dehydrogenase 2) and two unidentified m/z values (1305.840 and 1661.060) that were significantly higher in patients with shorter survival (0-3 years relative to 4-6 years and 7+ years). This is the first study using MALDI-MSI, combined with LC-MS/MS, on a large cohort of CRLM patients to identify the spatial proteome in this malignancy. Further, we identify several protein candidates that may be suitable for drug targeting or for future prognostic biomarker development.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
  2. Lee PY, Yeoh Y, Omar N, Pung YF, Lim LC, Low TY
    Crit Rev Clin Lab Sci, 2021 11;58(7):513-529.
    PMID: 34615421 DOI: 10.1080/10408363.2021.1942781
    Matrix-assisted laser desorption/ionization (MALDI) imaging is an emergent technology that has been increasingly adopted in cancer research. MALDI imaging is capable of providing global molecular mapping of the abundance and spatial information of biomolecules directly in the tissues without labeling. It enables the characterization of a wide spectrum of analytes, including proteins, peptides, glycans, lipids, drugs, and metabolites and is well suited for both discovery and targeted analysis. An advantage of MALDI imaging is that it maintains tissue integrity, which allows correlation with histological features. It has proven to be a valuable tool for probing tumor heterogeneity and has been increasingly applied to interrogate molecular events associated with cancer. It provides unique insights into both the molecular content and spatial details that are not accessible by other techniques, and it has allowed considerable progress in the field of cancer research. In this review, we first provide an overview of the MALDI imaging workflow and approach. We then highlight some useful applications in various niches of cancer research, followed by a discussion of the challenges, recent developments and future prospect of this technique in the field.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  3. Chua HS, Soh YH, Loong SK, AbuBakar S
    Ann Clin Microbiol Antimicrob, 2021 Oct 03;20(1):72.
    PMID: 34602092 DOI: 10.1186/s12941-021-00475-2
    BACKGROUND: Francisella philomiragia is a very rare opportunistic pathogen of humans which causes protean diseases such as pneumonia and other systemic infections. Subsequent failure of prompt treatment may result in poor prognosis with mortality among infected patients.

    CASE PRESENTATION: The present report describes a case of F. philomiragia bacteraemia first reported in Malaysia and Asian in a 60-year-old patient with underlying end-stage renal disease (ESRF) and diabetes mellitus. He presented with Acute Pulmonary Oedema with Non-ST-Elevation Myocardial Infarction (NSTEMI) in our hospital. He was intubated in view of persistent type I respiratory failure and persistent desaturation despite post haemodialysis. Blood investigation indicated the presence of ongoing infection and inflammation. The aerobic blood culture growth of F. philomiragia was identified using the matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry (Score value: 2.16) and confirmed by 16S Ribosomal DNA (16S rDNA) sequencing. He was discharged well on day 26 of admission, after completing one week of piperacillin/tazobactam and two weeks of doxycycline.

    CONCLUSION: Clinical suspicion should be raised if patients with known risk factors are presenting with pneumonia or pulmonary nodules especially as these are the most common manifestations of F. philomiragia infection. Early diagnosis via accurate laboratory identification of the organism through MALDI-TOF mass spectrometry and molecular technique such as 16S rDNA sequencing are vital for prompt treatment that results in better outcomes for the afflicted patients.

    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  4. Alharbi A, Al-Dubaib M, Elhassan MAS, Elbehiry A
    Trop Biomed, 2021 Jun 01;38(2):9-24.
    PMID: 33973568 DOI: 10.47665/tb.38.2.032
    The emergence of methicillin-resistant Staphylococcus aureus (MRSA) infection is one of the greatest threats to both animal and human health. Our investigation was aimed to identify and differentiate between MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) recovered from mastitic milk using MALDI-TOF mass spectrometry compared with phenotypic methods and studying their susceptibility to various antibiotics. Four hundred milk samples from mastitic animals (cows, sheep, goats, and dromedary camels) were investigated. Phenotypic identification of S. aureus was made through MASTASAPH Latex test, STAPH ID 32, and Vitek 2 system. The proteomic characterization of S. aureus was done by MBT. The Kirby Bauer method was accomplished to detect the resistance of S. aureus strains to antibiotics. The results of the MASTASAPH Latex test, revealed that 54 (46%) were recognized as S. aureus. All S. aureus isolates were identified by MBT with a score of more or equal 2.00. Several peaks were identified in the mass of 4590 Da, 4863 Da, and 4938 Da for MSSA and in the mass of 2636 Da and 3009 Da for MRSA. The MSP dendrogram demonstrated that the S. aureus isolates were classified into one group with a distance level of less or equal 400. The percentage of S. aureus resistance against carbenicillin, erythromycin and kanamycin was 94.4%, 38.88%, and 33.33%, respectively. In conclusion, S. aureus bacteria are among the key triggers for mastitis in Saudi Arabia. MBT is reported to be not only the rapid tool to identify S. aureus but also able to discriminate MRSA from MSSA.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  5. Tan XY, Misran A, Daim LDJ, Lau BYC
    Food Chem, 2021 May 01;343:128471.
    PMID: 33143964 DOI: 10.1016/j.foodchem.2020.128471
    Four different methods were evaluated to extract proteins from "Musang King" durian pulps and subsequently proteins with different abundance between fresh and long term frozen storage were identified using two-dimensional polyacrylamide gel electrophoresis coupled with matrix-assisted laser desorption/ionization time-of-flight mass spectrometer analyses. The acetone-phenol method was found to produce good protein yields and gave the highest gel resolution and reproducibility. Differential protein analyses of the durian pulp revealed that 15 proteins were down-regulated and three other proteins were up-regulated after a year of frozen storage. Isoflavone reductase-like protein, S-adenosyl methionine synthase, and cysteine synthase isoform were up-regulated during frozen storage. The down-regulation of proteins in frozen durian pulps indicated that frozen storage has affected proteins in many ways, especially in their functions related to carbohydrate and energy metabolisms, cellular components, and transport processes. This study will enable future detailed investigations of proteins associated with quality attributes of durians to be studied.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  6. Fisol AFBC, Saidi NB, Al-Obaidi JR, Lamasudin DU, Atan S, Razali N, et al.
    Microb Ecol, 2021 Apr 22.
    PMID: 33890145 DOI: 10.1007/s00248-021-01757-0
    Rigidoporus microporus is the fungus accountable for the white root rot disease that is detrimental to the rubber tree, Hevea brasiliensis. The pathogenicity mechanism of R. microporus and the identity of the fungal proteins and metabolites involved during the infection process remain unclear. In this study, the protein and metabolite profiles of two R. microporus isolates, Segamat (SEG) and Ayer Molek (AM), were investigated during an in vitro interaction with H. brasiliensis. The isolates were used to inoculate H. brasiliensis clone RRIM 2025, and mycelia adhering to the roots of the plant were collected for analysis. Transmission electron microscope (TEM) images acquired confirms the hyphae attachment and colonization of the mycelia on the root of the H. brasiliensis clones after 4 days of inoculation. The protein samples were subjected to 2-DE analysis and analyzed using MALDI-ToF MS/MS, while the metabolites were extracted using methanol and analyzed using LC/MS-QTOF. Based on the differential analyses, upregulation of proteins that are essential for fungal evolution such as malate dehydrogenase, fructose 1,6-biphosphate aldolase, and glyceraldehyde-3-phosphate dehydrogenase hints an indirect role in fungal pathogenicity, while metabolomic analysis suggests an increase in acidic compounds which may lead to increased cell wall degrading enzyme activity. Bioinformatics analyses revealed that the carbohydrate and amino acid metabolisms were prominently affected in response to the fungal pathogenicity. In addition to that, other pathways that were significantly affected include "Protein Ubiquitination Pathway," Unfolded Protein Response," "HIFα Signaling," and "Sirtuin Signaling Pathway." The identification of responsive proteins and metabolites from this study promotes a better understanding of mechanisms underlying R. microporus pathogenesis and provides a list of potential biological markers for early recognition of the white root rot disease.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  7. Mittal P, Briggs M, Klingler-Hoffmann M, Kaur G, Packer NH, Oehler MK, et al.
    Anal Bioanal Chem, 2021 Apr;413(10):2721-2733.
    PMID: 33222001 DOI: 10.1007/s00216-020-03039-z
    It is well established that cell surface glycans play a vital role in biological processes and their altered form can lead to carcinogenesis. Mass spectrometry-based techniques have become prominent for analysing N-linked glycans, for example using matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS). Additionally, MALDI MS can be used to spatially map N-linked glycans directly from cancer tissue using a technique termed MALDI MS imaging (MALDI MSI). This powerful technique combines mass spectrometry and histology to visualise the spatial distribution of N-linked glycans on a single tissue section. Here, we performed N-glycan MALDI MSI on six endometrial cancer (EC) formalin-fixed paraffin-embedded (FFPE) tissue sections and tissue microarrays (TMA) consisting of eight EC patients with lymph node metastasis (LNM) and twenty without LNM. By doing so, several putative N-linked glycan compositions were detected that could significantly distinguish normal from cancerous endometrium. Furthermore, a complex core-fucosylated N-linked glycan was detected that could discriminate a primary tumour with and without LNM. Structural identification of these putative N-linked glycans was performed using porous graphitized carbon liquid chromatography tandem mass spectrometry (PGC-LC-MS/MS). Overall, we observed higher abundance of oligomannose glycans in tumour compared to normal regions with AUC ranging from 0.85-0.99, and lower abundance of complex N-linked glycans with AUC ranges from 0.03-0.28. A comparison of N-linked glycans between primary tumours with and without LNM indicated a reduced abundance of a complex core-fucosylated N-glycan (Hex)2(HexNAc)2(Deoxyhexose)1+(Man)3(GlcNAc)2, in primary tumour with associated lymph node metastasis. In summary, N-linked glycan MALDI MSI can be used to differentiate cancerous endometrium from normal, and endometrial cancer with LNM from endometrial cancer without.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods*
  8. Rehiman SH, Lim SM, Lim FT, Chin AV, Tan MP, Kamaruzzaman SB, et al.
    Int J Neurosci, 2020 Dec 15.
    PMID: 33280461 DOI: 10.1080/00207454.2020.1860038
    Objective: Alzheimer's disease (AD), the commonest form of dementia which is characterized by progressive decline in cognitive function, can only be definitively diagnosed after death. Although biomarkers may aid diagnosis, currently available AD biomarkers, which are predominantly based on cerebrospinal fluid and neuroimaging facilities, are either invasive or costly. Blood-based biomarkers for AD diagnosis are highly sought after due to its practicality at the clinic. This study was undertaken to determine the differential protein expression in plasma amongst Malaysian AD, mild cognitive impairment (MCI) and non-AD individuals. Methods: A proteomic approach which utilized two-dimensional differential in gel electrophoresis (2 D DIGE) was performed for blood samples from 15 AD, 14 MCI and 15 non-AD individuals. Results: Mass spectrometry (MS)-based protein identification via MALDI ToF/ToF showed that fibrinogen-β-chain (spot 64) and fibrinogen-γ-chain (spot 91) with differential expression ratio >1.5 were significantly upregulated (p 
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  9. Boyle ST, Mittal P, Kaur G, Hoffmann P, Samuel MS, Klingler-Hoffmann M
    J Proteome Res, 2020 10 02;19(10):4093-4103.
    PMID: 32870688 DOI: 10.1021/acs.jproteome.0c00511
    Tumorigenesis involves a complex interplay between genetically modified cancer cells and their adjacent normal tissue, the stroma. We used an established breast cancer mouse model to investigate this inter-relationship. Conditional activation of Rho-associated protein kinase (ROCK) in a model of mammary tumorigenesis enhances tumor growth and progression by educating the stroma and enhancing the production and remodeling of the extracellular matrix. We used peptide matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to quantify the proteomic changes occurring within tumors and their stroma in their regular spatial context. Peptides were ranked according to their ability to discriminate between the two groups, using a receiver operating characteristic tool. Peptides were identified by liquid chromatography tandem mass spectrometry, and protein expression was validated by quantitative immunofluorescence using an independent set of tumor samples. We have identified and validated four key proteins upregulated in ROCK-activated mammary tumors relative to those expressing kinase-dead ROCK, namely, collagen I, α-SMA, Rab14, and tubulin-β4. Rab14 and tubulin-β4 are expressed within tumor cells, whereas collagen I is localized within the stroma. α-SMA is predominantly localized within the stroma but is also expressed at higher levels in the epithelia of ROCK-activated tumors. High expression of COL1A, the gene encoding the pro-α 1 chain of collagen, correlates with cancer progression in two human breast cancer genomic data sets, and high expression of COL1A and ACTA2 (the gene encoding α-SMA) are associated with a low survival probability (COLIA, p = 0.00013; ACTA2, p = 0.0076) in estrogen receptor-negative breast cancer patients. To investigate whether ROCK-activated tumor cells cause stromal cancer-associated fibroblasts (CAFs) to upregulate expression of collagen I and α-SMA, we treated CAFs with medium conditioned by primary mammary tumor cells in which ROCK had been activated. This led to abundant production of both proteins in CAFs, clearly highlighting the inter-relationship between tumor cells and CAFs and identifying CAFs as the potential source of high levels of collagen 1 and α-SMA and associated enhancement of tissue stiffness. Our research emphasizes the capacity of MALDI-MSI to quantitatively assess tumor-stroma inter-relationships and to identify potential prognostic factors for cancer progression in human patients, using sophisticated mouse cancer models.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  10. Harika K, Shenoy VP, Narasimhaswamy N, Chawla K
    J Glob Infect Dis, 2020 08 29;12(3):129-134.
    PMID: 33343163 DOI: 10.4103/jgid.jgid_150_19
    Background: Microorganisms are known to be involved in the formation of biofilm. These biofilms are often seen in chronic wound infections, surgical site infections, implants etc., These are capable of causing recalcitrant infections and most of them are also known to possess high antibiotic resistance.

    Objectives: This study was conducted to detect the biofilm formation in bacterial isolates from chronic wound infections.

    Materials and Methods: In the present study, ninety two isolates from chronic wound infections were identified by MALDI-TOF-MS (bioMerieux) and VITEK-2-MS (bioMerieux). These isolates were further screened for biofilm formation by three methods i. e., Tissue Culture Plate method (TCP), Tube Method (TM) and Congo Red Agar (CRA) method. Impact of biofilm production was correlated with the antibiotic resistant pattern.

    Statistical Analysis: Statistical analysis was done for all three methods considering TCP as Gold Standard and parameters like senitivity and specificity of TM i.e. 47.2 and 100% respectively.

    Results: Out of 92 isolates, biofilm formation was seen in 72 isolates (78.2%) by TCP method. 64 isolates were strong biofilm producers, 8 isolates were moderate biofilm producers and 20 isolates were nonbiofilm producing. High prevalence of biofilm formation was seen in nonhealing ulcers infected with Staphylococcus aureus followed by Klebsiella pneumoniae.

    Conclusion: Among three screening methods used for detection of biofilm production, TCP method is considered to be a standard and most reliable for screening of biofilm formation in comparison to TM and CRA.

    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  11. Briggs MT, Condina MR, Ho YY, Everest-Dass AV, Mittal P, Kaur G, et al.
    Proteomics, 2019 11;19(21-22):e1800482.
    PMID: 31364262 DOI: 10.1002/pmic.201800482
    Epithelial ovarian cancer is one of the most fatal gynecological malignancies in adult women. As studies on protein N-glycosylation have extensively reported aberrant patterns in the ovarian cancer tumor microenvironment, obtaining spatial information will uncover tumor-specific N-glycan alterations in ovarian cancer development and progression. matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is employed to investigate N-glycan distribution on formalin-fixed paraffin-embedded ovarian cancer tissue sections from early- and late-stage patients. Tumor-specific N-glycans are identified and structurally characterized by porous graphitized carbon-liquid chromatography-electrospray ionization-tandem mass spectrometry (PGC-LC-ESI-MS/MS), and then assigned to high-resolution images obtained from MALDI-MSI. Spatial distribution of 14 N-glycans is obtained by MALDI-MSI and 42 N-glycans (including structural and compositional isomers) identified and structurally characterized by LC-MS. The spatial distribution of oligomannose, complex neutral, bisecting, and sialylated N-glycan families are localized to the tumor regions of late-stage ovarian cancer patients relative to early-stage patients. Potential N-glycan diagnostic markers that emerge include the oligomannose structure, (Hex)6 + (Man)3 (GlcNAc)2 , and the complex neutral structure, (Hex)2 (HexNAc)2 (Deoxyhexose)1 + (Man)3 (GlcNAc)2 . The distribution of these markers is evaluated using a tissue microarray of early- and late-stage patients.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  12. Zhan SZ, Li JH, Zhang GH, Liu XW, Li M, Zheng J, et al.
    Chem Commun (Camb), 2019 Oct 03;55(80):11992-11995.
    PMID: 31498358 DOI: 10.1039/c9cc05236d
    A luminescent edge-interlocked heteroleptic metallocage based on Cu3(pyrazolate)3 was prepared through a ligand replacement reaction from a homoleptic metallocage and a new ligand. Its structure was confirmed by XRD and MALDI-TOF mass spectrometry. Theoretical calculations revealed the new ligand was evidently responsible for the bathochromic shift of the optimal excitation. This work provides a heteroleptic strategy to regulate the interlocking fashion and photophysical mechanism of metallocages based on Cu3(pyrazolate)3.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  13. Rayanakorn A, Katip W, Goh BH, Oberdorfer P, Lee LH
    Infect Drug Resist, 2019;12:3955-3965.
    PMID: 32021313 DOI: 10.2147/IDR.S233326
    Purpose: Streptococcus suis (S. suis) is an emerging zoonotic disease mainly in pigs, causing serious infections in humans with high prevalence in Southeast Asia. Despite a relatively high mortality rate, there are limited data regarding the risk factors of this life-threatening infection. Therefore, a 13-year retrospective cohort study in Chiang Mai, Thailand during 2005-2018 was conducted to explore risk factors associated with S. suis mortality and to update the outcomes of the disease.

    Patients and methods: S. suis positive cases were derived from those with positive S. suis isolates from microbiological culture results and Matrix-Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF). Potential risk factors of mortality were identified using univariate and multivariate logistic regression.

    Results: Of 133 patients with culture-proven S. suis infection identified, there were 92 males and 41 females. The mean age was 56.47 years. Septicemia (55.64%) was the most common clinical manifestation followed by meningitis (37.59%) and infective endocarditis (25.56%). Alcohol drinking and raw pork consumption were documented in 66 (49.62%) and 49 (36.84%) cases respectively. The overall mortality rate was 12.03% (n=16). According to the multivariate analysis, the independent risk factors for mortality were prolonged bacteremia ≥ 6 days (OR = 43.57, 95% CI = 2.46-772.80, P =0.010), septic shock (OR = 13.34, 95% CI = 1.63-109.03, P =0.016), and direct bilirubin > 1.5 mg/dL (OR = 12.86, 95% CI = 1.91-86.59, P =0.009).

    Conclusion: S. suis is not infrequent in Northern Thailand, where the cultural food habit of raw pork eating is still practiced. To the best of our knowledge, this is the largest series focusing on risk factors of S. suis mortality which has been conducted in Thailand. Prolonged bacteremia ≥ 6 days, septic shock, and direct bilirubin > 1.5 mg/dL were strong predictors associated with S. suis mortality. The mortality risk factors identified may be further utilized in clinical practice and future research to improve patient outcomes.

    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  14. Maarof M, Lokanathan Y, Ruszymah HI, Saim A, Chowdhury SR
    Protein J, 2018 12;37(6):589-607.
    PMID: 30343346 DOI: 10.1007/s10930-018-9800-z
    Growth factors and extracellular matrix (ECM) proteins are involved in wound healing. Human dermal fibroblasts secrete wound-healing mediators in culture medium known as dermal fibroblast conditioned medium (DFCM). However, the composition and concentration of the secreted proteins differ with culture conditions and environmental factors. We cultured human skin fibroblasts in vitro using serum-free keratinocyte-specific media (EpiLife™ Medium [KM1] and defined keratinocyte serum-free medium [KM2]) and serum-free fibroblast-specific medium (FM) to obtain DFCM-KM1, DFCM-KM2 and DFCM-FM, respectively. We identified and compared their proteomic profiles using bicinchoninic acid assay (BCA), 1-dimensional sodium dodecyl sulphate-polyacrylamide gel electrophoresis (1D SDS-PAGE), enzyme-linked immunosorbent assay (ELISA), matrix-assisted laser desorption ionisation-time-of-flight mass spectrometry (MALDI-TOF/TOF MS/MS) and liquid chromatography MS (LC-MS/MS). DFCM-KM1 and DFCM-KM2 had higher protein concentrations than DFCM-FM but not statistically significant. MALDI-TOF/TOF MS identified the presence of fibronectin, serotransferrin, serpin and serum albumin. LC-MS/MS and bioinformatics analysis identified 59, 46 and 58 secreted proteins in DFCM-KM1, DFCM-KM2 and DFCM-FM, respectively. The most significant biological processes identified in gene ontology were cellular process, metabolic process, growth and biological regulation. STRING® analysis showed that most secretory proteins in the DFCMs were associated with biological processes (e.g. wound healing and ECM organisation), molecular function (e.g. ECM binding) and cellular component (e.g. extracellular space). ELISA confirmed the presence of fibronectin and collagen in the DFCMs. In conclusion, DFCM secretory proteins are involved in cell adhesion, attachment, proliferation and migration, which were demonstrated to have potential wound-healing effects by in vitro and in vivo studies.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization/methods
  15. Ng YL, Olivos-García A, Lim TK, Noordin R, Lin Q, Othman N
    Am J Trop Med Hyg, 2018 12;99(6):1518-1529.
    PMID: 30298805 DOI: 10.4269/ajtmh.18-0415
    Entamoeba histolytica is a protozoan parasite that causes amebiasis and poses a significant health risk for populations in endemic areas. The molecular mechanisms involved in the pathogenesis and regulation of the parasite are not well characterized. We aimed to identify and quantify the differentially abundant membrane proteins by comparing the membrane proteins of virulent and avirulent variants of E. histolytica HM-1:IMSS, and to investigate the potential associations among the differentially abundant membrane proteins. We performed quantitative proteomics analysis using isobaric tags for relative and absolute quantitation labeling, in combination with two mass spectrometry instruments, that is, nano-liquid chromatography (nanoLC)-matrix-assisted laser desorption/ionization-mass spectrometry/mass spectrometry and nanoLC-electrospray ionization tandem mass spectrometry. Overall, 37 membrane proteins were found to be differentially abundant, whereby 19 and 18 membrane proteins of the virulent variant of E. histolytica increased and decreased in abundance, respectively. Proteins that were differentially abundant include Rho family GTPase, calreticulin, a 70-kDa heat shock protein, and hypothetical proteins. Analysis by Protein ANalysis THrough Evolutionary Relationships database revealed that the differentially abundant membrane proteins were mainly involved in catalytic activities (29.7%) and metabolic processes (32.4%). Differentially abundant membrane proteins that were found to be involved mainly in the catalytic activities and the metabolic processes were highlighted together with their putative roles in relation to the virulence. Further investigations should be performed to elucidate the roles of these proteins in E. histolytica pathogenesis.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  16. Pakalapati H, Arumugasamy SK, Jewaratnam J, Wong YJ, Khalid M
    Biopolymers, 2018 Dec;109(12):e23240.
    PMID: 30489632 DOI: 10.1002/bip.23240
    A statistical approach with D-optimal design was used to optimize the process parameters for polycaprolactone (PCL) synthesis. The variables selected were temperature (50°C-110°C), time (1-7 h), mixing speed (50-500 rpm) and monomer/solvent ratio (1:1-1:6). Molecular weight was chosen as response and was determined using matrix-assisted laser desorption/ionization time of flight (MALDI TOF). Using the D-optimal method in design of experiments, the interactions between parameters and responses were analysed and validated. The results show a good agreement with a minimum error between the actual and predicted values.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  17. Ling HL, Rahmat Z, Bakar FDA, Murad AMA, Illias RM
    Microbiol Res, 2018 Oct;215:46-54.
    PMID: 30172308 DOI: 10.1016/j.micres.2018.06.006
    Bacillus lehensis G1 is an alkaliphilic bacterium that is capable of surviving in environments up to pH 11. Secretome related to bacterial acclimation in alkaline environment has been less studied compared to cytoplasmic and membrane proteome. The aim of this study was to gain better understanding of bacterial acclimation to alkaline media through analyzing extracellular proteins of B. lehensis. The pH range for B. lehensis growth was conducted, and two-dimensional electrophoresis and MALDI-TOF/TOF MS analysis were conducted to characterize changes in protein profiling in B. lehensis cultured at pH 8 and pH 11 when compared with those cultured at pH 10 (optimal growth pH). B. lehensis could grow well at pH ranging from 8 to 11 in which the bacteria showed to posses thinner flagella at pH 11. Proteomic analyses demonstrated that five proteins were up-regulated and 13 proteins were down-regulated at pH 8, whereas at pH 11, 14 proteins were up-regulated and 8 were down-regulated. Majority of the differentially expressed proteins were involved in the cell wall, main glycolytic pathways, the metabolism of amino acids and related molecules and some proteins of unknown function. A total of 40 differentially expressed protein spots corresponding to 33 proteins were identified; including GlcNAc-binding protein A, chitinase, endopeptidase lytE, flagellar hook-associated proteins and enolase. These proteins may play important roles in acclimation to alkaline media via reallocation of cell wall structure and changes to cell surface glycolytic enzymes, amino acid metabolism, flagellar hook-associated proteins and chaperones to sustain life under pH-stressed conditions.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  18. Nielsen HL, Tarpgaard IH, Fuglsang-Damgaard D, Thomsen PK, Brisse S, Dalager-Pedersen M
    JMM Case Rep, 2018 Aug;5(8):e005163.
    PMID: 30323938 DOI: 10.1099/jmmcr.0.005163
    Introduction: Elizabethkingia anophelis is a Gram-negative, aerobic, non-motile rod belonging to the family Flavobacteriaceae. Over the last 5 years, it has emerged as an opportunistic human pathogen involved in neonatal meningitis and sepsis, as well as nosocomial outbreaks. It has been isolated from the midgut of the Anopheles gambiae mosquito, but there is no evidence for a role of the mosquito in human infections, and very little is known regarding the routes of transmission to humans. Recent studies, primarily from South-East Asia, suggest that E. anophelis, and not Elizabethkingia meningoseptica, is the predominant human pathogen of this genus. However, identification to the species level has been difficult due to the limitations of the current MALDI-TOF MS (matrix-associated laser desorption ionization-time of flight MS) systems for correct species identification.

    Case presentation: Here, we present a rare case of E. anophelis meningitis in a Danish male, who had a travel exposure to Malaysia 7 weeks before hospitalization. A multidrug-resistant Elizabethkingia species was isolated from blood and cerebrospinal fluid, and genomic sequencing was used to characterize the phylogenetic position of the isolate, which was determined as associated with previously described sublineage 11. The patient was successfully treated with intravenous moxifloxacin and rifampicin for 2 weeks with no major sequelae, but we did not find the source of transmission.

    Conclusion: All clinical microbiologists should be aware of the present limitations of the MALDI-TOF MS systems for correct species identification, and therefore we recommend the use of genome sequencing for the correct identification at the species and sublineage level.

    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  19. Rahim MAA, Rahim ZHA, Ahmad WAW, Bakri MM, Ismail MD, Hashim OH
    Acta Pharmacol Sin, 2018 Jul;39(7):1197-1207.
    PMID: 29417940 DOI: 10.1038/aps.2017.141
    An early intervention using biomarkers to predict acute myocardial infarction (AMI) will effectively reduce global heart attack incidence, particularly among high-risk patients with type 2 diabetes mellitus (T2DM). This study attempted to identify potential biomarkers by detecting changes in the levels of plasma proteins in T2DM patients following onset of AMI in comparison with those without AMI. Volunteer T2DM patients without AMI (control; n=10) and T2DM patients with AMI (n=10) were recruited. Plasma samples from these patients were evaluated via two-dimensional gel electrophoresis (2DE) to screen for proteins with level changes between the two groups. The abundance of spots on gel images was analyzed using Progenesis SameSpots and subjected to false discovery rate (FDR) analysis. Protein spots with statistically significant changes of at least 1.5 fold were selected for mass spectrometry (MS) analysis. Due to strong cardiac connections, tetranectin and titin were evaluated by enzymelinked immunosorbent assay (ELISA). The adjusted P-values and fold changes between the two groups resulted in identification of 34 protein spots with significantly altered abundance. Upon MS analysis, 17 plasma proteins were identified: tetranectin, titin, clusterin, haptoglobin, myosin-13, zinc fnger protein 445, DNA repair protein RAD50, serum albumin, apolipoprotein A-IV, caspase-6, aminoacyl tRNA synthase complex-interacting multifunctional protein 1, serotransferrin, retinol-binding protein 4, transthyretin, alpha-1-antitrypsin, apolipoprotein A-I and serum amyloid A. Comparable patterns of changes in tetranectin and titin between the control and AMI groups were confirmed using ELISA. In summary, tetranectin and titin in plasma appeared to be closely associated with the onset of AMI among T2DM patients and can be used as potential biomarkers for prediction of a cardiac event, though this requires validation in a prospective cohort study.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
  20. Heskes AM, Sundram TCM, Boughton BA, Jensen NB, Hansen NL, Crocoll C, et al.
    Plant J, 2018 03;93(5):943-958.
    PMID: 29315936 DOI: 10.1111/tpj.13822
    Vitex agnus-castus L. (Lamiaceae) is a medicinal plant historically used throughout the Mediterranean region to treat menstrual cycle disorders, and is still used today as a clinically effective treatment for premenstrual syndrome. The pharmaceutical activity of the plant extract is linked to its ability to lower prolactin levels. This feature has been attributed to the presence of dopaminergic diterpenoids that can bind to dopamine receptors in the pituitary gland. Phytochemical analyses of V. agnus-castus show that it contains an enormous array of structurally related diterpenoids and, as such, holds potential as a rich source of new dopaminergic drugs. The present work investigated the localisation and biosynthesis of diterpenoids in V. agnus-castus. With the assistance of matrix-assisted laser desorption ionisation-mass spectrometry imaging (MALDI-MSI), diterpenoids were localised to trichomes on the surface of fruit and leaves. Analysis of a trichome-specific transcriptome database, coupled with expression studies, identified seven candidate genes involved in diterpenoid biosynthesis: three class II diterpene synthases (diTPSs); three class I diTPSs; and a cytochrome P450 (CYP). Combinatorial assays of the diTPSs resulted in the formation of a range of different diterpenes that can account for several of the backbones of bioactive diterpenoids observed in V. agnus-castus. The identified CYP, VacCYP76BK1, was found to catalyse 16-hydroxylation of the diol-diterpene, peregrinol, to labd-13Z-ene-9,15,16-triol when expressed in Saccharomyces cerevisiae. Notably, this product is a potential intermediate in the biosynthetic pathway towards bioactive furan- and lactone-containing diterpenoids that are present in this species.
    Matched MeSH terms: Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
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