Application of Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Imaging Mass Spectrometry (MALDI-TOF IMS) for Premalignant Gastrointestinal Lesions

Accuracy of matrix-assisted laser desorption ionization time-of-flight mass spectrometry for direct bacterial identification from culture-positive urine samples

Background

Urinary tract infection (UTI) is one of the most frequent reasons for antimicrobial therapy. In typical clinical setting, 18–48 h is needed to identify pathogens by urine culture. A rapid method for pathogenic UTI diagnosis by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been developed in recent years.

Methods

This meta-analysis systematically evaluated the accuracy of MALDI-TOF MS for direct identification of bacteria from culture-positive urine samples. We queried the electronic database of Medline and Web of Science to obtain relevant articles.

Results

Nineteen articles involving 4,579 isolates were included after final selection in the meta-analysis. The random-effects pooled identification accuracy of MALDI-TOF MS was 0.82 with 95% confidence interval of 0.79 to 0.86 at the species level. For Gram-negative isolates, the correct identification performance of the species ranged from 0.54 to 0.98, with a cumulative rate of 0.87 (95% CI: 0.83 to 0.91). For Gram-positive isolates, the correct identification rate ranged from 0.32 to 0.80, with a cumulative rate of 0.59 (95% CI: 0.49 to 0.68).

Conclusions

MALDI-TOF MS provides a reliable direct identification of bacteria, particularly in cases of Gram-negative isolates, from clinical urine specimens. Nevertheless, the identification accuracy of this method is moderate for Gram-positive bacteria.

Predictive proteomic biomarkers for inflammatory bowel disease-associated cancer: Where are we now in the era of the next generation proteomics?

Recent advances in genomic medicine have opened up the possibility of tailored medicine that may eventually replace traditional “one-size-fits all” approaches to the treatment of inflammatory bowel disease (IBD). In addition to exploring the interactions between hosts and microbes, referred to as the microbiome, a variety of strategies that can be tailored to an individual in the coming era of personalized medicine in the treatment of IBD are being investigated. These include prompt genomic screening of patients at risk of developing IBD, the utility of molecular discrimination of IBD subtypes among patients diagnosed with IBD, and the discovery of proteome biomarkers to diagnose or predict cancer risks. Host genetic factors influence the etiology of IBD, as do microbial ecosystems in the human bowel, which are not uniform, but instead represent many different microhabitats that can be influenced by diet and might affect processes essential to bowel metabolism. Further advances in basic research regarding intestinal inflammation may reveal new insights into the role of inflammatory mediators, referred to as the inflammasome, and the macromolecular complex of metabolites formed by intestinal bacteria. Collectively, knowledge of the inflammasome and metagenomics will lead to the development of biomarkers for IBD that target specific pathogenic mechanisms involved in the spontaneous progress of IBD. In this review article, our recent results regarding the discovery of potential proteomic biomarkers using a label-free quantification technique are introduced and on-going projects contributing to either the discrimination of IBD subtypes or to the prediction of cancer risks are accompanied by updated information from IBD biomarker research.

Molecular imaging for theranostics in gastroenterology: one stone to kill two birds

Molecular imaging in gastroenterology has become more feasible with recent advances in imaging technology, molecular genetics, and next-generation biochemistry, in addition to advances in endoscopic imaging techniques including magnified high-resolution endoscopy, narrow band imaging or autofluorescence imaging, flexible spectral imaging color enhancement, and confocal laser endomicroscopy. These developments have the potential to serve as "red flag" techniques enabling the earlier and accurate detection of mucosal abnormalities (such as precancerous lesions) beyond biomarkers, virtual histology of detected lesions, and molecular targeted therapy-the strategy of "one stone to kill two or three birds"; however, more effort should be done to be "blue ocean" benefit. This review deals with the introduction of Raman spectroscopy endoscopy, imaging mass spectroscopy, and nanomolecule development for theranostics. Imaging of molecular pathological changes in cells/tissues/organs might open the "royal road" to either convincing diagnosis of diseases that otherwise would only be detected in the advanced stages or novel therapeutic methods targeted to personalized medicine.

Imaging mass spectrometry in papillary thyroid carcinoma for the identification and validation of biomarker proteins

Direct tissue imaging mass spectrometry (IMS) by matrix-assisted laser desorption ionization and time-of-flight (MALDI-TOF) mass spectrometry has become increasingly important in biology and medicine, because this technology can detect the relative abundance and spatial distribution of interesting proteins in tissues. Five thyroid cancer samples, along with normal tissue, were sliced and transferred onto conductive glass slides. After laser scanning by MALDI-TOF equipped with a smart beam laser, images were created for individual masses and proteins were classified at 200-µm spatial resolution. Based on the spatial distribution, region-specific proteins on a tumor lesion could be identified by protein extraction from tumor tissue and analysis using liquid chromatography with tandem mass spectrometry (LC-MS/MS). Using all the spectral data at each spot, various intensities of a specific peak were detected in the tumor and normal regions of the thyroid. Differences in the molecular weights of expressed proteins between tumor and normal regions were analyzed using unsupervised and supervised clustering. To verify the presence of discovered proteins through IMS, we identified ribosomal protein P2, which is specific for cancer. We have demonstrated the feasibility of IMS as a useful tool for the analysis of tissue sections, and identified the tumor-specific protein ribosomal protein P2.

Recent advances in molecular imaging of premalignant gastrointestinal lesions and future application for early detection of barrett esophagus

Recent advances in optical molecular imaging allow identification of morphologic and biochemical changes in tissues associated with gastrointestinal (GI) premalignant lesions earlier and in real-time. This focused review series introduces high-resolution imaging modalities that are being evaluated preclinically and clinically for the detection of early GI cancers, especially Barrett esophagus and esophageal adenocarcinoma. Although narrow band imaging, autofluorescence imaging, and chromoendoscopy are currently applied for this purpose in the clinic, further adoptions of probe-based confocal laser endomicroscopy, high-resolution microendoscopy, optical coherence tomography, and metabolomic imaging, as well as imaging mass spectrometry, will lead to detection at the earliest and will guide predictions of the clinical course in the near future in a manner that is beyond current advancements in optical imaging. In this review article, the readers will be introduced to sufficient information regarding this matter with which to enjoy this new era of high technology and to confront science in the field of molecular medical imaging.