Mid-trimester amniotic fluid proteome's association with spontaneous preterm delivery and gestational duration

BACKGROUND

Amniotic fluid is clinically accessible via amniocentesis and its protein composition may correspond to birth timing. Early changes in the amniotic fluid proteome could therefore be associated with the subsequent development of spontaneous preterm delivery.

OBJECTIVE

The main objective of this study was to perform unbiased proteomics analysis of the association between mid-trimester amniotic fluid proteome and spontaneous preterm delivery and gestational duration, respectively. A secondary objective was to validate and replicate the findings by enzyme-linked immunosorbent assay using a second independent cohort.

METHODS

Women undergoing a mid-trimester genetic amniocentesis at Sahlgrenska University Hospital/Östra between September 2008 and September 2011 were enrolled in this study, designed in three analytical stages; 1) an unbiased proteomic discovery phase using LC-MS analysis of 22 women with subsequent spontaneous preterm delivery (cases) and 37 women who delivered at term (controls), 2) a validation phase of proteins of interest identified in stage 1, and 3) a replication phase of the proteins that passed validation using a second independent cohort consisting of 20 cases and 40 matched controls.

RESULTS

Nine proteins were nominally significantly associated with both spontaneous preterm delivery and gestational duration, after adjustment for gestational age at sampling, but none of the proteins were significant after correction for multiple testing. Several of these proteins have previously been described as being associated with spontaneous PTD etiology and six of them were thus validated using enzyme linked immunosorbent assay. Two of the proteins passed validation; Neutrophil gelatinase-associated lipocalin and plasminogen activator inhibitor 1, but the results could not be replicated in a second cohort.

CONCLUSIONS

Neutrophil gelatinase-associated lipocalin and Plasminogen activator inhibitor 1 are potential biomarkers of spontaneous preterm delivery and gestational duration but the findings could not be replicated. The negative findings are supported by the fact that none of the nine proteins from the exploratory phase were significant after correction for multiple testing.

Conventional-Flow Liquid Chromatography-Mass Spectrometry for Exploratory Bottom-Up Proteomic Analyses

Due to its sensitivity and productivity, bottom-up proteomics based on liquid chromatography-mass spectrometry (LC-MS) has become the core approach in the field. The de facto standard LC-MS platform for proteomics operates at sub-μL/min flow rates, and nanospray is required for efficiently introducing peptides into a mass spectrometer. Although this is almost a "dogma", this view is being reconsidered in light of developments in highly efficient chromatographic columns, and especially with the introduction of exceptionally sensitive MS instruments. Although conventional-flow LC-MS platforms have recently penetrated targeted proteomics successfully, their possibilities in discovery-oriented proteomics have not yet been thoroughly explored. Our objective was to determine what are the extra costs and what optimization and adjustments to a conventional-flow LC-MS system must be undertaken to identify a comparable number of proteins as can be identified on a nanoLC-MS system. We demonstrate that the amount of a complex tryptic digest needed for comparable proteome coverage can be roughly 5-fold greater, providing the column dimensions are properly chosen, extra-column peak dispersion is minimized, column temperature and flow rate are set to levels appropriate for peptide separation, and the composition of mobile phases is fine-tuned. Indeed, we identified 2 835 proteins from 2 μg of HeLa cells tryptic digest separated during a 60 min gradient at 68 μL/min on a 1.0 mm × 250 mm column held at 55 °C and using an aqua-acetonitrile mobile phases containing 0.1% formic acid, 0.4% acetic acid, and 3% dimethyl sulfoxide. Our results document that conventional-flow LC-MS is an attractive alternative for bottom-up exploratory proteomics.

Determination of ascorbic acid in pharmaceutical preparation and fruit juice using modified carbon paste electrode

Acrobic acid is key substance in the human metabolism and the rapid and accurate determination in food is of a great interest. Ascorbic acid is an electroactive compound, however poorly responded on the bare carbon paste electrodes. In this paper, brilliant cresyl blue and multi-walled carbon nanotubes were used for the modification of carbon paste electrode. Brilliant cresyl blue acts as a mediator improving the transition of electrons, whereas multiwalled carbon nanotubes increased the surface of the electrode. Both brilliant cresyl blue and multiwalled carbon nanotubes were added directly to the composite material. The electrochemical behavior of modified electode was determined in electrolyte at various pH, and the effect of the scan rate was also performed. It was shown that the electrochemical process on the surface of the modified carbon paste electrode was diffusion-controlled. The resulted modified carbon paste electrode showed a good electrocatalytic activity towards the oxidation of ascorbic acid at a reduced overpotential of +100 mV descreasing the risk of interferences. A linear response of the ascorbic acid oxidation current measured by the amperometry in the range of 0.1 - 350 µmol.L-1 was obtained applying the sensor for the standard solution. The limit of detection and limit of quantification was found to be 0.05 and 0.15 µmol.L-1, respectively. The novel method was applied for the determination of ascorbic acid in pharmaceutical vitamin preparation and fruit juice, and the results were in good agreement with the standard HPLC method. The presented modification of carbon paste electrode is suitable for the fast, sensitive and very accurate determination of ascorbic acid in fruit juices and pharmaceutical preparation.

Proteomic analysis of cerebrospinal fluid for relapsing-remitting multiple sclerosis and clinically isolated syndrome

Early diagnosis and treatment of multiple sclerosis (MS) in the initial stages of the disease can significantly retard its progression. The aim of the present study was to identify changes in the cerebrospinal fluid proteome in patients with relapsing-remitting MS and clinically isolated MS syndrome who are at high risk of developing MS (case group) compared to healthy population (control) in order to identify potential new markers, which could ultimately aid in early diagnosis of MS. The protein concentrations of each of the 11 case and 15 control samples were determined using a bicinchoninic acid assay. Nanoscale liquid chromatography coupled with tandem mass spectrometry was used for protein identification. Proteomics data were processed using the Perseus software suite and R. The results were filtered using the Benjamini-Hochberg procedure for the false discovery rate (FDR) correction (FDR<0.05). The results showed that, 26 proteins were significantly dysregulated in case samples compared to the controls. Nine proteins were found to be significantly less abundant in case samples, while the abundance of 17 proteins was significantly increased in case samples compared to controls. Three of the proteins were previously linked to RR MS, including immunoglobulin (Ig) γ-1 chain C region, Ig heavy chain V–III region BRO and Ig κ chain C region. Three proteins that were uniquely expressed in patients with RR MS were identified and these proteins may serve as prognostic biomarkers for identifying patients with a high risk of developing RR MS.

Tetrazole regioisomers in the development of nitro group-containing antitubercular agents

Tetrazole derivatives containing nitro substituents have been identified as promising antitubercular agents.

[Proteomics and biomarkers for detection of preterm labor: a systematic review]

OBJECTIVE

To review the published articles about identification of biomarkers of spontaneous preterm birth using a proteomic approach and to create a list of potential biomarkers.

DESIGN

Systematic review of literature.

SETTING

Department of Obstetrics and Gynecology, Medical Faculty Charles University Hradec Kralove.

METHODS

The following databases were accessed in search of relevant citation: MEDLINE, SCOPUS and PubMed. Totally 101 references were identified and relevant 37 abstracts were screened. As appropriated were pointed 16 studies. Finally, the data were extracted from five articles.

CONCLUSION

The implementation of high-throughput technologies is necessary in the field of spontaneous preterm birth research. A compelling option is the use of proteomics in the area spontaneous preterm birth biomarkers identification in amniotic fluid, maternal serum/plasma, cervical-vaginal fluid and placental tissue. The data was extracted from published articles and a list of 72 proteins was created.

Application of proteomics in biomarker discovery: a primer for the clinician

Ever since proteomics was proven to be capable of characterizing a large number of differences in both protein quality and quantity, it has been applied in various areas of biomedicine, ranging from the deciphering molecular pathogenesis of diseases to the characterization of novel drug targets and the discovery of potential diagnostic biomarkers. Indeed, the biomarker discovery in human plasma is clearly one of the areas with enormous potential. However, without proper planning and implementation of specific techniques, the efforts and expectations may very easily be hampered. Numerous earlier projects aimed at clinical proteomics, characterized by exaggerated enthusiasm, often underestimated some principal obstacles of plasma biomarker discovery. Consequently, ambiguous and insignificant results soon led to a more critical view in this field. In this article, we critically review the current state of proteomic approaches for biomarker discovery and validation, in order to provide basic information and guidelines for both clinicians and researchers. These need to be closely considered prior to initiation of a project aimed at plasma biomarker discovery. We also present a short overview of recent applications of clinical proteomics in biomarker discovery.

[Proteomics and biomarkers for detection of ovarian cancer]

OBJECTIVE

The purpose of this study was to focuse on recent developments on the evolving field of biomarker discovery and validation techniques using proteomics platforms for ovarian cancer.

DESIGN

Review.

SETTING

Department of Obstetrics and Gynecology Medical Faculty Charles University Hradec Kralove. Institute of Molecular Pathology. Faculty of Military Health Sciences, University of Defense, Hradec Kralove.

METHODS

The last decade has seen major changes in the technologies used to identify markers for diagnosing early stages of ovarian cancer. Currently the major developments were made in three distinct areas: protein profilig, highthroughput validation techniques and solid and liquid phase protein microarray platforms for analyzing candidate markers across stages hold significant of ovarian cancer. These new technologies hold significant promise in identifying more robust markers for ovarian cancer.

CONCLUSION

The present review summarizes the results of clinical and experimental research on biomarkers of ovarian cancer.