Surface-enhanced Laser Desorption Ionization Time Research Articles

A SELDI-TOF approach to ecotoxicology: comparative profiling of low molecular weight proteins from a marine diatom exposed to CdSe/ZnS quantum dots

Quantum dots (QDs), namely semiconductor nanocrystals, due to their particular optical and electronic properties, have growing applications in device technology, biotechnology and biomedical fields. Nevertheless, the possible threat to human health and the environment have attracted increasing attention as the production and applications of QDs increases rapidly while standard evaluation of safety lags.In the present study we performed proteomic analyses, by means of 2D gel electrophoresis and Surface Enhanced Laser Desorption Ionization-Time of Flight-Mass Spectrometry (SELDI-TOF-MS). We aimed to identify potential biomarkers of exposure to CdSe/ZnS quantum dots. The marine diatom Phaeodactylum tricornutum exposed to 2.5nM QDs was used as a model system. Both 2DE and SELDI showed the presence of differentially expressed proteins. By Principal Component Analysis (PCA) we were able to show that the differentially expressed proteins can discriminate between exposed and not exposed cells. Furthermore, a protein profile specific for exposed cells was obtained by SELDI analysis. To our knowledge, this is the first example of the application of SELDI technology to the analysis of microorganisms used as biological sentinel model of marine environmental pollution.

Differential expression and clinical significance of serum protein among patients with clear-cell renal cell carcinoma

Looking for tumor markers by using protein chip technology is one of the hot topics, but many studies are still limited on short term detection of differential expressed proteins before and after surgery among patients with RCC. This study analyzed differential expressed serum protein and its clinical significance with clear-cell renal cell carcinoma to further measurement of the rule of variable expressing. Eighty-nine patients with clear-cell renal cell carcinoma who underwent surgery from November 2013 to 2014 and postoperatively confirmed by pathology were entered in RCC group, 100 healthy volunteers and patients without RCC who underwent medical examination in the same period were entered in control group. The serum protein were analyzed in both group before surgery and every regular follow-up period in 1 year after surgery with RCC group. The surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS) and weak cation exchange protein chip (CM10) technology systems were used for identifying differential expressed serum protein in RCC group and controls. The linear support vector machine (SVM) was applied to establish the diagnostic model of protein fingerprints and the leave-one-out cross validation was used for determining model discriminating effect. The differential expressed proteins were analyzed by ZUCI-PDAS protein spectral data analysis system. Five kinds of proteins were identified as potential biomarker, ultimately. The M/Z of these proteins was 15953, 7987, 9304, 8948, 5911, respectively. There were significant difference on expression level of these proteins with two groups preoperatively (P< 0.05). Comparison of all postoperative expression levels to preoperative one and each differential level mutually between a year in postoperative period also revealed statistical significance (P< 0.05). With taking identified proteins as biomarker, the sensitivity and specificity in predicting clear-cell renal cell carcinoma was 88.8% (79/89) and 91.0% (91/100), respectively. The corresponding specific protein was Bcl-2 family apoptosis regulatory proteins, WAP four-disulfide core protein, Krueppel-like factor 8, monocyte chemotactic protein-1, serum amyloid β -protein-4, respectively, and will may serve as tumor markers of kidney cancer. These proteins manifests high predictive value for clear-cell renal cell carcinoma, and may contribute to therapeutic evaluation, prognosis and targeted therapy for clear-cell renal cell carcinoma.

New horizon in dialysis depuration: Characterization of a polysulfone membrane able to break the 'albumin wall'.

The uremic syndrome is attributed to the progressive retention of a large number of toxins, which under normal conditions are excreted by the healthy kidneys. Standard dialytic membranes do not purify middle-high molecular weight toxins. Haemodiafiltration with endogenous reinfusion coupled with a highly permeable membrane could break the limit of the 'albumin wall' improving the dialytic depuration without loss of important nutrients. The aim of this study was to evaluate the performance of a new polysulfone membrane, Synclear 0.2, to remove uremic molecules. Surface Enhanced Laser Desorption Ionization-Time of Flight was employed to evaluate the proteomic profile of ultrafiltrate and Electrospray Ionization-Quadruple-ToF coupled with on-chip elution was used for proteins identification. A high and specific permeability for middle-high molecular weight molecules was revealed by mass spectrometry for the investigated membrane. The identified proteins are mostly uremic toxins: their relative abundance, estimated in the ultrafiltrate by exponentially modified protein abundance index, showed a high purification efficiency of the new membrane when compared with conventional ones. In conclusion, Synclear 0.2, used as convective membrane in hemodiafiltration with endogenous reinfusion treatment, permits to break the 'albumin wall', clearing middle-high molecular weight uremic toxins, improving the dialytic treatment purification efficiency.

Screening and identification of potential biomarkers and establishment of the diagnostic serum proteomic model for the Traditional Chinese Medicine Syndromes of tuberculosis

Ethnopharmacological relevanceChemotherapy is the mainstay of modern tuberculosis (TB) control. Traditional Chinese Medicine (TCM) can enhance the effect of anti-TB drug, promote the absorption of the foci in the lung and reduce drug toxicity. In TCM, the determination of treatment is based on ZHENG (also called TCM syndrome). To establish a diagnostic model by using proteomics technology in order to identify potential biomarkers for TCM syndromes of TB. Materials and methodsThe surface-enhanced laser desorption ionization time of flight mass spectrometer (SELDI–TOF MS) combined with weak cation exchange (WCX) magnetic beads was used to screen serum samples from 71 cases of deficiency of lung yin syndrome (DLYS), 64 cases of fire (yang) excess yin deficiency syndrome (FEYDS) and 45 cases of deficiency of both qi and yin syndrome (DQYS). A classification model was established by Biomarker Pattern Software (BPS). Candidate protein biomarkers were purified by reverse phase-high performance liquid chromatograph (RP-HPLC), identified by MALDI–TOF MS, LC–MS/MS and validated by ProteinChip Immunoassays. ResultsA total of 74 discriminating m/z peaks (P<0.001) among three TCM syndromes of TB were detected. A diagnostic model for the TCM syndrome of TB based on the five biomarkers (3961.7, 4679.7, 5646.4, 8891.2 and 9416.7 m/z) was established which could discriminate DLYS, FEYDS and DQYS patients with an accuracy of 74.0%, 72.5%, and 96.7%, respectively. The candidate biomarker with m/z of 9416.7 was identified as a fragment of apolipoprotein C-III (apoC-III) by MALDI–TOF-MS and LC–MS/MS. ConclusionThe TCM syndrome diagnostic model of TB could successfully distinguish the three TCM syndromes of TB patients. This provided a biological basis for the determination of treatment based on different TCM syndromes of TB. ApoC-III was identified as a potential biomarker for TCM syndromes of TB and revealed the biochemical basis and pathogenesis of TCM syndromes in TB.

The effects of frozen tissue storage conditions on the integrity of RNA and protein

Unfixed tissue specimens most frequently are stored for long term research uses at either −80° C or in vapor phase liquid nitrogen (VPLN). There is little information concerning the effects such long term storage on tissue RNA or protein available for extraction. Aliquots of 49 specimens were stored for 5–12 years at −80° C or in VPLN. Twelve additional paired specimens were stored for 1 year under identical conditions. RNA was isolated from all tissues and assessed for RNA yield, total RNA integrity and mRNA integrity. Protein stability was analyzed by surface-enhanced or matrix-assisted laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS, MALDI-TOF-MS) and nano-liquid chromatography electrospray ionization tandem mass spectrometry (nLC-ESI-MS/MS). RNA yield and total RNA integrity showed significantly better results for −80° C storage compared to VPLN storage; the transcripts that were preferentially degraded during VPLN storage were these involved in antigen presentation and processing. No consistent differences were found in the SELDI-TOF-MS, MALDI-TOF-MS or nLC-ESI-MS/MS analyses of specimens stored for more than 8 years at −80° C compared to those stored in VPLN. Long term storage of human research tissues at −80° C provides at least the same quality of RNA and protein as storage in VPLN.

Epidemiological tools for effective surveillance of porcine cysticercosis in Africa

Porcine cysticercosis is widely distributed in developing countries. Many tools were developed for effective control of the tapeworm in endemic countries. Tongue examination, meat inspection and Ag-ELISA were widely used in epidemiological survey. Both tongue examination and meat inspection are highly specific but less sensitive. To improve performance of AgELISA, unambiguous test based on nanobodies was performed. Immunodiagnostic tests based on PCR, flows through assay (FTA), Surface Enhanced Laser Desorption–Ionization Time of Flight (SELDI-TOF) were also developed. Less data were reported using spatial statistical analysis hence multiples approaches were available for effective epidemiological survey of porcine cysticercosis.

Mitochondrial proteomic analysis of ecdysterone protection against oxidative damage in human lens epithelial cells.

To investigate the protective effects of the natural medicinal monomer ecdysterone (ECR) with estrogenic activity against oxidative damage in human lens epithelial cells B3 (HLE-B3) caused by hydrogen peroxide 21(H2O2) and to pursue the possible mitochondrial proteomic regularity of the protective effects. HLE-B3 cells were treated with H2O2 (300µmol/L), β-estuarial (E2; 10(-8)mol/L) and H2O2, ECR (10(-6)mol/L) and H2O2, or left untreated. Altered expression of all mitochondrial proteins was analyzed by protein array and surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS). The mass/charge (M/Z) ratios of each peak were tested by the Kruskal-Wallis rank sum test, and the protein peak value of the M/Z ratio for each treatment by pair comparison was analyzed with the Nemenyi test. H2O2 up-regulated expression of two protein spots (with M/Z of 6 532 and 6 809). When E2 mitigated the oxidative damage, the expression of one protein spot (M/Z 6 532) was down-regulated. In contrast, ECR down-regulated both of protein spots (M/Z 6 532 and 6 809). ECR could effectively inhibite H2O2 induced oxidative damage in HLE-B3 cells. The protein spot at M/Z of 6 532 might be the target spot of ECR against oxidative damage induced by H2O2.

The diagnostic performance of the Mass Restricted (MR) score in the identification of microbial invasion of the amniotic cavity or intra-amniotic inflammation is not superior to amniotic fluid interleukin-6

Objective: Intra-amniotic infection/inflammation are major causes of spontaneous preterm labor and delivery. However, diagnosis of intra-amniotic infection is challenging because most are subclinical and amniotic fluid (AF) cultures take several days before results are available. Several tests have been proposed for the rapid diagnosis of microbial invasion of the amniotic cavity (MIAC) or intra-amniotic inflammation. The aim of this study was to examine the diagnostic performance of the AF Mass Restricted (MR) score in comparison with interleukin-6 (IL-6) and matrix metalloproteinase-8 (MMP-8) for the identification of MIAC or inflammation.Methods: AF samples were collected from patients with singleton gestations and symptoms of preterm labor (n = 100). Intra-amniotic inflammation was defined as >100 white blood cells/mm3 (WBCs) in AF; MIAC was defined as a positive AF culture. AF IL-6 and MMP-8 were determined using ELISA. The MR score was obtained using the Surface-Enhanced Laser Desorption Ionization Time of Flight (SELDI-TOF) mass spectrometry. Sensitivity and specificity were calculated and logistic regression models were fit to construct receiver-operating characteristic (ROC) curves for the identification of each outcome. The McNemar’s test and paired sample non-parametric statistical techniques were used to test for differences in diagnostic performance metrics.Results: (1) The prevalence of MIAC and intra-amniotic inflammation was 34% (34/100) and 40% (40/100), respectively; (2) there were no significant differences in sensitivity of the three tests under study (MR score, IL-6 or MMP-8) in the identification of either MIAC or intra-amniotic inflammation (using the following cutoffs: MR score >2, IL-6 >11.4 ng/mL, and MMP-8 >23 ng/mL); (3) there was no significant difference in the sensitivity among the three tests for the same outcomes when the false positive rate was fixed at 15%; (4) the specificity for IL-6 was not significantly different from that of the MR score in identifying either MIAC or intra-amniotic inflammation when using previously reported thresholds; and (5) there were no significant differences in the area under the ROC curve when comparing the MR score, IL-6 or MMP-8 in the identification of these outcomes.Conclusions: IL-6 and the MR score have equivalent diagnostic performance in the identification of MIAC or intra-amniotic inflammation. Selection from among these three tests (MR score, IL-6 and MMP-8) for diagnostic purposes should be based on factors such as availability, reproducibility, and cost. The MR score requires a protein chip and a SELDI-TOF instrument which are not widely available or considered “state of the art”. In contrast, immunoassays for IL-6 can be performed in the majority of clinical laboratories.

The discovery and identification of a candidate proteomic biomarker of active tuberculosis

BackgroundNoninvasive and convenient biomarkers for early diagnosis of tuberculosis (TB) remain an urgent need. The aim of this study was to discover and identify potential biomarkers specific for TB.MethodsThe surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF MS) combined with weak cation exchange (WCX) magnetic beads was used to screen serum samples from 180 cases of TB and 211 control subjects. A classification model was established by Biomarker Pattern Software (BPS). Candidate protein biomarkers were purified by reverse phase-high performance liquid chromatography (RP-HPLC), identified by MALDI-TOF MS, LC-MS/MS and validated using enzyme-linked immunosorbent assay (ELISA).ResultsA total of 35 discriminating m/z peaks were detected that were related to TB (P < 0.01). The model of biomarkers based on the four biomarkers (2554.6, 4824.4, 5325.7, and 8606.8 Da) was established which could distinguish TB from controls with the sensitivity of 83.3% and the specificity of 84.2%. The candidate biomarker with m/z of 2554.6 Da was found to be up-regulated in TB patients, and was identified as a fragment of fibrinogen, alpha polypeptide isoform alpha-E preproprotein. Analysis in 22 patients with TB showed increased fibrinogen degradation product (FDP) (5,005 ± 1,297 vs. 4,010 ± 1,181 ng/mL, P < 0.05) and in 142 patients showed elevated plasma fibrinogen levels.ConclusionsA diagnostic model for TB with high sensitivity and specificity was developed using mass spectrometry combined with magnetic beads. Fibrinogen was identified as a potential biomarker for TB and showed diagnostic values in clinical application.

The Human Urinary Proteome Fingerprint Database UPdb

The use of human urine as a diagnostic tool has many advantages, such as ease of sample acquisition and noninvasiveness. However, the discovery of novel biomarkers, as well as biomarker patterns, in urine is hindered mainly by a lack of comparable datasets. To fill this gap, we assembled a new urinary fingerprint database. Here, we report the establishment of a human urinary proteomic fingerprint database using urine from 200 individuals analysed by SELDI-TOF (surface enhanced laser desorption ionisation-time of flight) mass spectrometry (MS) on several chip surfaces (SEND, HP50, NP20, Q10, CM10, and IMAC30). The database currently lists 2490 unique peaks/ion species from 1172 nonredundant SELDI analyses in the mass range of 1500 to 150000. All unprocessed mass spectrometric scans are available as “.xml” data files. Additionally, 1384 peaks were included from external studies using CE (capillary electrophoresis)-MS, MALDI (matrix assisted laser desorption/ionisation), and CE-MALDI hybrids. We propose to use this platform as a global resource to share and exchange primary data derived from MS analyses in urinary research.

Analysis of serum proteome profiles in nasopharyngeal carcinoma with different radiosensitivity

The research is endeavored to establish a serum protein fingerprint model for predicting radiosensitivity of nasopharyngeal carcinoma through the analysis of the serum expressed proteins of the pre- and post-treatment nasopharyngeal carcinoma patients treated with radiotherapy. Surface-enhanced laser desorption ionization-time of flight-mass spectrometry and CM-10 protein chip were used to detect the serum proteomic patterns of 50 nasopharyngeal carcinoma patients with different radiosensitivity. Thirty-eight of the 50 patients after the treatment were also studied. Biomarker Wizard 3.01 and Biomarker Pattern 5.01 were used in combination to analyze the data and to develop predicting models. At the molecular weight range of 2,000-20,000, the software identified an average of 83 mass peaks between radiation sensitive group and radiation resistant group. 11 protein peaks were significantly different. Of the 83 mass peaks, 4 mass peaks (mass/charge ratio [m/z] 2,575, 3,942, 6,117 and 6,778) were chosen automatically to construct a classification tree. The diagnostic accuracy was 78.0 %. M/z 6,117 and 6,778 of the radiation sensitive group after the treatment trended to those of the radiation resistant group. The technology of surface-enhanced laser desorption ionization-time of flight-mass spectrometry can be used to screen and identify differentially expressed proteins associated with different radiosensitivity in nasopharyngeal cancer. It should be a very useful tool for predicting radiosensitivity of nasopharyngeal carcinoma.

SELDI‐TOF MS Combined With Magnetic Beads for Detecting Serum Protein Biomarkers for Diagnosis of Active Tuberculosis

New technologies for the early detection of tuberculosis (TB) are urgently needed. The aim of the present study was to screen for the potential protein biomarkers in serum for the diagnosis of TB using proteomic fingerprint technology. The surface‐enhanced laser desorption ionization time of flight mass spectrometry (SELDI‐TOF‐ MS) combined with WCX magnetic beads was used to profile the serum proteins from 180 patients with TB, 91 cases of healthy volunteers, 40 cases of lung cancer patients, 40 cases of pneumonia patients, and 40 cases of chronic obstructive pulmonary disease. The protein fingerprint expression of all the serum samples and the resulting profiles between TB and control groups were analyzed with the Biomarker Wizard system. A total of 35 discriminating m/z peaks were detected that were related to TB (p &lt; 0.01). The model of biomarkers based on the four biomarkers (2554.6, 4824.4, 5325.7, and 8606.8 Da) generated excellent separation between the TB and control groups. The sensitivity was 83.3% and the specificity was 84.2%. Blind test data indicated a sensitivity of 75.0% and a specificity of 83.5%. The data suggested a potential application of SELDI‐TOF MS as an effective technology to profile serum proteome, and with pattern analysis, a diagnostic model comprising three potential biomarkers was indicated to differentiate people with TB and healthy controls rapidly and precisely.This work was supported by grants from National Special Sci‐Tech Projects (No. 2012ZX10005001–006), National Natural Science Foundation of China (No. 81072724, No. 81273882), and Zhejiang Province Special Sci‐Tech Projects (No. 2009C03011–3).

Attempted Validation of Surface Enhanced Laser Desorption Ionization-Time of Flight Derived Kinesin Biomarkers in Malignant Mesothelioma

Surface-enhanced Laser Desorption/Ionization Time-of-flight (SELDI-TOF) mass spectrometry allows researchers to search proteomes for biomarkers of disease. Validating SELDI-TOF results using traditional methodologies has yielded mixed results. Real-time PCR, ELISA and Western blot assays were utilized in an attempt to confirm the link between asbestos related cancers and kinesin family proteins, KIF5A and KIF18A. These proteins had been identified using SELDI-TOF and Classification and Regression Tree Analysis (CART) in serum of patients with asbestos related cancers. When well-characterized asbestos fibers were used to challenge mesothelial cell lines, mixed results in KIF5A and KIF18A RNA expression were observed. Western blot analysis comparing protein levels in mesothelioma cell lines versus transformed mesothelial cells yielded inconclusive results, as did Western blot analyses of human mesothelioma and non-cancerous peritoneum that had been obtained from the same patients. These results suggest that kinesin family proteins detected by SELDI-TOF CART are unlikely to be of use as biomarkers for malignant mesothelioma.

Longitudinal Analysis of Maternal Plasma Apolipoproteins in Pregnancy: A Targeted Proteomics Approach

Minimally invasive diagnostic tests are needed in obstetrics to identify women at risk for complications during delivery. The apolipoproteins fluctuate in complexity and abundance in maternal plasma during pregnancy and could be incorporated into a blood test to evaluate this risk. The objective of this study was to examine the relative plasma concentrations of apolipoproteins and their biochemically modified subtypes (i.e. proteolytically processed, sialylated, cysteinylated, dimerized) over gestational time using a targeted mass spectrometry approach. Relative abundance of modified and unmodified apolipoproteins A-I, A-II, C-I, C-II, and C-III was determined by surface-enhanced laser desorption/ionization-time of flight-mass spectrometry in plasma prospectively collected from 11 gravidas with uncomplicated pregnancies at 4-5 gestational time points per patient. Apolipoproteins were readily identifiable by spectral pattern. Apo C-III(2) and Apo C-III(1) (doubly and singly sialylated Apo C-III subtypes) increased with gestational age (r(2)>0.8). Unmodified Apo A-II, Apo C-I, and Apo C-III(0) showed no correlation (r(2) = 0.01-0.1). Pro-Apo C-II did not increase significantly until third trimester (140 ± 13% of first trimester), but proteolytically cleaved, mature Apo C-II increased in late pregnancy (702 ± 130% of first trimester). Mature Apo C-II represented 6.7 ± 0.9% of total Apo C-II in early gestation and increased to 33 ± 4.5% in third trimester. A label-free, semiquantitative targeted proteomics approach was developed using LTQ-Orbitrap mass spectrometry to confirm the relative quantitative differences observed by surface-enhanced laser desorption/ionization-time of flight-mass spectrometry in Apo C-III and Apo C-II isoforms between first and third trimesters. Targeted apolipoprotein screening was applied to a cohort of term and preterm patients. Modified Apo A-II isoforms were significantly elevated in plasma from mothers who delivered prematurely relative to term controls (p = 0.02). These results support a role for targeted proteomics profiling approaches in monitoring healthy pregnancies and assessing risk of adverse obstetric outcomes.

Mitochondrial proteomic analysis of isopsoralen protection against oxidative damage in human lens epithelial cells

To investigate the protective effects of the natural medicinal monomer isopsoralen (ISR) with estrogenic activity against oxidative damage in human lens epithelial cells B3 (HLE-B3) caused by hydrogen peroxide (H(2)O(2)) and to pursue the possible mitochondrial proteomic regularity of the protective effects. HLE-B3 cells were treated with H(2)O(2) (300 μ mol/L), β-estradiol (E(2): 10(-8) mol/L) and H(2)O(2), ISR (10(-5) mol/L) and H(2)O(2), or left untreated. Altered expressions of all mitochondrial proteins were analyzed by protein array and surfaceenhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS). The mass/charge (m/z) ratios of each peak were tested by the Kruskal-Wallis rank sum test, and the protein peak value of the m/z ratio for each treatment by pair comparison was analyzed with the Nemenyi test. H(2)O(2) up-regulated the expressions of two protein spots (with m/z of 6532 and 6809). E(2) mitigated the oxidative damage, and the expression of one protein spot (m/z 6532) was down-regulated. In contrast, ISR down-regulated both of protein spots (m/z 6532 and 6809). ISR could effectively inhibit H(2)O(2)-induced oxidative damage in HLE-B3 cells. The protein spot at m/z of 6532 might be the target spot of ISR against oxidative damage induced by H(2)O(2).

N-truncated Aβ peptides in complex fluids unraveled by new specific immunoassays

Previous studies have highlighted the potential physiopathological and diagnostic role of N- and C-terminally truncated amyloid-β (Aβ) peptides in Alzheimer's disease. However, our knowledge about their production remains incomplete, in part due to the lack of very specific and sensitive tools for their detection. We thus developed specific monoclonal antibodies that target either Aβ11-x or Aβ17-x species, which result from the combined cleavages by β/γ- or α/γ-secretases, respectively. The presence of Aβ peptides truncated at residue 11 and 17 peptides was qualitatively and quantitatively assessed, using surface enhanced laser desorption ionization-time of flight mass spectrometry and xMAP (Multi-Analyte Profiling) immunoassays, in the supernatant of HEK293 cells that overexpress wild type or mutant Aβ protein precursor or in which α- and β-secretase activities had been modulated. Our results show a differential secretion of Aβ11–40 and Aβ17–40 species by these HEK293 cell lines. Finally, Aβ11–40 concentration in human cerebrospinal fluid (measured with the new xMAP immunoassays) from a first pilot study was higher in cerebrospinal fluid samples from patients with Alzheimer's disease than in samples from patients with other types of dementia.

Combined mRNA microarray and proteomic analysis of eutopic endometrium of women with and without endometriosis

An early semi-invasive diagnosis of endometriosis has the potential to allow early treatment and minimize disease progression but no such test is available at present. Our aim was to perform a combined mRNA microarray and proteomic analysis on the same eutopic endometrium sample obtained from patients with and without endometriosis. mRNA and protein fractions were extracted from 49 endometrial biopsies obtained from women with laparoscopically proven presence (n= 31) or absence (n= 18) of endometriosis during the early luteal (n= 27) or menstrual phase (n= 22) and analyzed using microarray and proteomic surface enhanced laser desorption ionization-time of flight mass spectrometry, respectively. Proteomic data were analyzed using a least squares-support vector machines (LS-SVM) model built on 70% (training set) and 30% of the samples (test set). mRNA analysis of eutopic endometrium did not show any differentially expressed genes in women with endometriosis when compared with controls, regardless of endometriosis stage or cycle phase. mRNA was differentially expressed (P< 0.05) in women with (925 genes) and without endometriosis (1087 genes) during the menstrual phase when compared with the early luteal phase. Proteomic analysis based on five peptide peaks [2072 mass/charge (m/z); 2973 m/z; 3623 m/z; 3680 m/z and 21133 m/z] using an LS-SVM model applied on the luteal phase endometrium training set allowed the diagnosis of endometriosis (sensitivity, 91; 95% confidence interval (CI): 74-98; specificity, 80; 95% CI: 66-97 and positive predictive value, 87.9%; negative predictive value, 84.8%) in the test set. mRNA expression of eutopic endometrium was comparable in women with and without endometriosis but different in menstrual endometrium when compared with luteal endometrium in women with endometriosis. Proteomic analysis of luteal phase endometrium allowed the diagnosis of endometriosis with high sensitivity and specificity in training and test sets. A potential limitation of our study is the fact that our control group included women with a normal pelvis as well as women with concurrent pelvic disease (e.g. fibroids, benign ovarian cysts, hydrosalpinges), which may have contributed to the comparable mRNA expression profile in the eutopic endometrium of women with endometriosis and controls.

Screening and identification of serum proteomic biomarkers for gastric adenocarcinoma.

The aim of the present study was to screen for possible serum biomarkers for gastric adenocarcinoma. Surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS) was used to screen serum samples from 109 cases of gastric adenocarcinoma and 106 control subjects (60 healthy subjects, 30 patients with chronic superficial gastritis and 16 cases of chronic atrophic gastritis). The differentially expressed protein peaks were selected and isolated using high performance liquid chromatography (HPLC) and processed with enzyme prior to liquid chromatography-mass spectrometry tandem mass spectrometry (LC-MS/MS) analysis and data mining with software XCalibur program components BioWorks 3.2. Among the gastric cancer cases, three differentially expressed protein peaks were selected as potential serum biomarkers: the m/z peaks at 5,906.5 showed increased expression (8.53±4.33 in the cancer group, and 0.88±0.31 in the control group); the m/z peaks at 6,635.7 and 8,716.3 showed decreased expression (6.54±2.44 and 0.93±0.29, respectively, in the cancer group and 17.56±4.43 and 2.16±0.98, respectively, in the control group) (P<0.01). The m/z peaks at 5,906.5, 6,635.7 and 8,716.3, were identified as fibrinogen α-chain, apolipo-protein A-II and apolipoprotein C-I. The combined use of the three biomarkers distinguished the cancer group patients from the control group samples at a sensitivity of 93.85% (61/65) and a specificity of 94.34% (50/53). In conclusion, fibrinogen α-chain, apolipoprotein A-II and apolipoprotein C-I were identified as potential markers for gastric cancer and appear to have diagnostic value for clinical applications.

Diagnostic serum proteomic analysis in patients with active tuberculosis

BackgroundThe diagnosis for smear-negative pulmonary tuberculosis (TB) is very difficult. Proteomic fingerprinting of sera is a potentially useful tool. MethodsThis study analyzed the results of the proteomic fingerprinting in sera obtained from active TB patients and controls using the surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF-MS) and protein-chip technology. The peaks were detected and analyzed, and a diagnostic system was developed. The protein peak was identified using high performance liquid chromatography (HPLC)–tandem matrix-assisted laser desorption/ionization-TOF-MS (MALDI-TOF-MS). ResultsAround 50 protein peaks were found significantly different between the TB patients and the controls (P<0.01). Three protein peaks at m/z 5643, 4486 and 4360 were selected for system classification and the development of a decision model. The model distinguished the TB patients from the controls with a sensitivity of 96.9% and a specificity of 97.8%, respectively. The diagnostic accuracy was up to 97.3%. The one most discrepant protein peak at m/z 5643 seen in sera of active TB patients was identified as orosomucoid. ConclusionsA diagnostic system for active TB was developed using mass spectrometry and protein chip technology and required only small-volume serum samples. One potential protein biomarker at m/z 5643 was identified as orosomucoid.

Identification of serum proteomic biomarkers for early porcine reproductive and respiratory syndrome (PRRS) infection

BackgroundPorcine reproductive and respiratory syndrome (PRRS) is one of the most significant swine diseases worldwide. Despite its relevance, serum biomarkers associated with early-onset viral infection, when clinical signs are not detectable and the disease is characterized by a weak anti-viral response and persistent infection, have not yet been identified. Surface-enhanced laser desorption ionization time of flight mass spectrometry (SELDI-TOF MS) is a reproducible, accurate, and simple method for the identification of biomarker proteins related to disease in serum. This work describes the SELDI-TOF MS analyses of sera of 60 PRRSV-positive and 60 PRRSV-negative, as measured by PCR, asymptomatic Large White piglets at weaning. Sera with comparable and low content of hemoglobin (< 4.52 μg/mL) were fractionated in 6 different fractions by anion-exchange chromatography and protein profiles in the mass range 1–200 kDa were obtained with the CM10, IMAC30, and H50 surfaces.ResultsA total of 200 significant peaks (p < 0.05) were identified in the initial discovery phase of the study and 47 of them were confirmed in the validation phase. The majority of peaks (42) were up-regulated in PRRSV-positive piglets, while 5 were down-regulated. A panel of 14 discriminatory peaks identified in fraction 1 (pH = 9), on the surface CM10, and acquired at low focus mass provided a serum protein profile diagnostic pattern that enabled to discriminate between PRRSV-positive and -negative piglets with a sensitivity and specificity of 77% and 73%, respectively.ConclusionsSELDI-TOF MS profiling of sera from PRRSV-positive and PRRSV-negative asymptomatic piglets provided a proteomic signature with large scale diagnostic potential for early identification of PRRSV infection in weaning piglets. Furthermore, SELDI-TOF protein markers represent a refined phenotype of PRRSV infection that might be useful for whole genome association studies.