scholarly journals Imaging Mass Spectrometry by Matrix-Assisted Laser Desorption/Ionization and Stress-Strain Measurements in Iontophoresis Transepithelial Corneal Collagen Cross-Linking

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Paolo Vinciguerra ◽  
Rita Mencucci ◽  
Vito Romano ◽  
Eberhard Spoerl ◽  
Fabrizio I. Camesasca ◽  
...  
Keyword(s):  
Imaging Mass Spectrometry ◽  
Laser Desorption ◽  
Cross Linking ◽  
Laser Desorption Ionization ◽  
Stress Strain ◽  
Strain Measurements ◽  
Maldi Ims ◽  
Corneal Rigidity ◽  
Collagen Cross Linking ◽  
Corneal Collagen

Purpose.To compare biomechanical effect, riboflavin penetration and distribution in transepithelial corneal collagen cross-linking with iontophoresis (I-CXL), with standard cross linking (S-CXL) and current transepithelial protocol (TE-CXL).Materials and Methods.The study was divided into two different sections, considering, respectively, rabbit and human cadaver corneas. In both sections corneas were divided according to imbibition protocols and irradiation power. Imaging mass spectrometry by matrix-assisted laser desorption/ionization (MALDI-IMS) and stress-strain measurements were used. Forty-eight rabbit and twelve human cadaver corneas were evaluated.Results.MALDI-IMS showed a deep riboflavin penetration throughout the corneal layers with I-CXL, with a roughly lower concentration in the deepest layers when compared to S-CXL, whereas with TE-CXL penetration was considerably less. In rabbits, there was a significant increase (by 71.9% andP=0.05) in corneal rigidity after I-CXL, when compared to controls. In humans, corneal rigidity increase was not significantly different among the subgroups.Conclusions.In rabbits, I-CXL induced a significant increase in corneal stiffness as well as better riboflavin penetration when compared to controls and TE-CXL but not to S-CXL. Stress-strain in human corneas did not show significant differences among techniques, possibly because of the small sample size of groups. In conclusion, I-CXL could be a valid alternative to S-CXL for riboflavin delivery in CXL, preserving the epithelium.

scholarly journals Lipidoak aztertu eta identifikatzeko TLC kromatografiaren eta MALDI masa-espektrometriaren arteko akoplamendua

2018 ◽  
pp. 149-165
Author(s):  
Antonio Veloso
Keyword(s):  
Mass Spectrometry ◽  
Imaging Mass Spectrometry ◽  
Laser Desorption ◽  
Laser Desorption Ionization ◽  
Ionization Time ◽  
Flight Mass Spectrometry ◽  
Maldi Ims ◽  
Layer Chromatography ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Geruza meheko kromatografia teknika (TLC, ingelesezko Thin Layer Chromatography) oso erabilia izan da hainbat molekularen banaketa eta karakterizaziorako. Bestalde, Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) edo matrizez lagundutako laserraren bidezko desortzioionizazioa/hegaldi-denbora masa-espektrometria teknikaren erabilera gero eta gehiago hedatzen ari da molekula desberdinen analisia egiteko. Gainera, Imaging Mass Spectrometry (IMS) edo masa-espektrometriaren bidezko irudia izeneko teknikak, ahalbidetzen du ehun biologikoetan dauden lipidoen, proteinen eta farmakoen banaketa-irudiak lortzea eta teknika bikaina da molekula horien banaketa aztertzeko. Teknika honek lipido mota ezberdinen identifikazioa eta lokalizazioa ahalbidetzen du, konposatuaren edota familia kimikoaren aukera egin aurretik. Analizatu behar diren konposatuen aukera aldez aurretik egin behar ez denez, aukera dago irudiak sortzeko masa-espektrometroan detektatutako ioietatik abiatuta. Lan honetan, erakusten da lipidoen ikerkuntzarako oso lagungarria dela TLC xaflak eta MALDI IMS teknikak konbinatzea.

scholarly journals Short communication: Distribution of phospholipids in parotid cancer by matrix-assisted laser desorption/ionization imaging mass spectrometry

PLoS ONE ◽  
2021 ◽  
Vol 16 (12) ◽  
pp. e0261491
Author(s):  
Hirofumi Kanetake ◽  
Nahoko Kato-Kogoe ◽  
Tetsuya Terada ◽  
Yoshitaka Kurisu ◽  
Wataru Hamada ◽  
...  
Keyword(s):  
Imaging Mass Spectrometry ◽  
Laser Desorption ◽  
Negative Ion ◽  
Laser Desorption Ionization ◽  
Parotid Cancer ◽  
Desorption Ionization ◽  
Maldi Ims ◽  
Cancer Tissues ◽  
Matrix Assisted Laser ◽  
Matrix Assisted Laser Desorption

Background Parotid cancer is relatively rare, and malignancy varies; therefore, novel markers are needed to predict prognosis. Recent advances in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-IMS), useful for visualization of lipid molecules, have revealed the relationship between cancer and lipid metabolism, indicating the potential of lipids as biomarkers. However, the distribution and importance of phospholipids in parotid cancer remain unclear. Objective This study aimed to use MALDI-IMS to comprehensively investigate the spatial distribution of phospholipids characteristically expressed in human parotid cancer tissues. Methods Tissue samples were surgically collected from two patients with parotid cancer (acinic cell carcinoma and mucoepidermoid carcinoma). Frozen sections of the samples were assessed using MALDI-IMS in both positive and negative ion modes, with an m/z range of 600–1000. The mass spectra obtained in the tumor and non-tumor regions were compared and analyzed. Ion images corresponding to the peak characteristics of the tumor regions were visualized. Results Several candidate phospholipids with significantly different expression levels were detected between the tumor and non-tumor regions. The number of unique lipid peaks with significantly different intensities between the tumor and non-tumor regions was 95 and 85 for Cases 1 and 2, respectively, in positive ion mode, and 99 and 97 for Cases 1 and 2, respectively, in negative ion mode. Imaging differentiated the characteristics that phospholipids were heterogeneously distributed in the tumor regions. Conclusion Phospholipid candidates that are characteristically expressed in human parotid cancer tissues were found, demonstrating the localization of their expression. These findings are notable for further investigation of alterations in lipid metabolism of parotid cancer and may have potential for the development of phospholipids as biomarkers.

scholarly journals Application of Imaging Mass Spectrometry to Assess Ocular Drug Transit

2017 ◽  
Vol 22 (10) ◽  
pp. 1239-1245 ◽  
Author(s):  
Kerri J. Grove ◽  
Viral Kansara ◽  
Melissa Prentiss ◽  
Debby Long ◽  
Muneto Mogi ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Imaging Mass Spectrometry ◽  
Laser Desorption ◽  
Topical Administration ◽  
Posterior Segment ◽  
Target Tissue ◽  
Laser Desorption Ionization ◽  
Maldi Ims ◽  
Preclinical Species ◽  
Ocular Distribution

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) is becoming an important technology to determine the distribution of drugs and their metabolites in the tissue of preclinical species after dosing. Interest in IMS is growing in the ophthalmology field, but little work to this point has been done to investigate ocular drug transit using this technology. Information on where and how a drug is distributing through the eye is important in understanding efficacy and whether it is reaching the desired target tissue. For this study, ocular distribution of brimonidine was investigated in rabbits following topical administration. Brimonidine has been shown to lower intraocular pressure and is approved to treat glaucoma, the second leading cause of blindness in the world. We have developed IMS methods to assess transit of topically administered brimonidine from the anterior to the posterior segment of rabbit eyes. Using IMS, brimonidine was detected in the cornea, aqueous humor, iris, and posterior segments of the eye. The distribution of brimonidine suggests that the route of transit following topical administration is mainly through the uvea-scleral route. This study demonstrates that IMS can be applied to assess ocular transit and distribution of topically administered drugs.

scholarly journals Dual polarity MALDI imaging mass spectrometry on the same pixel points reveals spatial lipid localizations at high-spatial resolutions in rat small intestine

2018 ◽  
Vol 10 (21) ◽  
pp. 2428-2435 ◽  
Author(s):  
Ibrahim Kaya ◽  
Eva Jennische ◽  
Stefan Lange ◽  
Per Malmberg
Keyword(s):  
Mass Spectrometry ◽  
Imaging Mass Spectrometry ◽  
Laser Desorption ◽  
Maldi Imaging ◽  
Jejunal Mucosa ◽  
Rat Small Intestine ◽  
Laser Desorption Ionization ◽  
Desorption Ionization ◽  
Maldi Ims ◽  
Dual Polarity

Sensitive laser desorption/ionization obtained via a sublimation-coated 1,5 diaminonaphthalene (1,5-DAN) matrix allowed dual polarity MALDI-IMS analysis on the same pixel points across the jejunal mucosa.

scholarly journals Multiplex enzyme activity imaging by MALDI-IMS of substrate library conversions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Oliver Klein ◽  
Akvile Haeckel ◽  
Ulf Reimer ◽  
Grit Nebrich ◽  
Eyk Schellenberger
Keyword(s):  
Enzyme Activities ◽  
Imaging Mass Spectrometry ◽  
Laser Desorption ◽  
Biological Processes ◽  
Laser Desorption Ionization ◽  
Tissue Sections ◽  
Enzyme Substrate ◽  
Maldi Ims ◽  
Enzyme Amplification ◽  
Paraffin Tissue

Abstract Enzymes are fundamental to biological processes and involved in most pathologies. Here we demonstrate the concept of simultaneously mapping multiple enzyme activities (EA) by applying enzyme substrate libraries to tissue sections and analyzing their conversion by matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS). To that end, we spray-applied a solution of 20 naturally derived peptides that are known substrates for proteases, kinases, and phosphatases to zinc-fixed paraffin tissue sections of mouse kidneys. After enzyme conversion for 5 to 120 min at 37 °C and matrix application, the tissue sections were imaged by MALDI-IMS. We could image incubation time-dependently 16 of the applied substrates with differing signal intensities and 12 masses of expected products. Utilizing inherent enzyme amplification, EA-IMS can become a powerful tool to locally study multiple, potentially even lowly expressed, enzyme activities, networks, and their pharmaceutical modulation. Differences in the substrate detectability highlight the need for future optimizations.

scholarly journals Reevaluating the Effectiveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes

2017 ◽  
Vol 6 (1) ◽  
pp. 34-41
Author(s):  
Damien Gatinel
Keyword(s):  
Diagnostic Tools ◽  
Cross Linking ◽  
Corneal Rigidity ◽  
Biomechanical Changes ◽  
Biomechanical Effect ◽  
Human Eyes ◽  
Collagen Cross Linking ◽  
Corneal Collagen

ABSTRACT The induction of cross-links in corneal tissue appears to be a promising technique to increase its stiffness and this has been the basis of treatment of keratoconus (KC) and corneal ectatic disease. However, there exists a striking discrepancy between the reported biomechanical effects of corneal collagen cross-linking (CXL) in vitro compared to in vivo, and this has not received much attention in the literature. Despite the documentation of an increase in corneal stiffness in vitro by many investigators, reports that provide evidence of measurable and consistent biomechanical changes in corneal rigidity in vivo after CXL are lacking. Indeed, the absence of documented in vivo biomechanical improvement in CXL-treated corneas is a conundrum, which needs to be further explored. To explain this discrepancy, it has been postulated that biomechanical changes induced by CXL are too subtle to be measured by currently available diagnostic tools or have characteristics not discernible by these technologies. However, the dynamic bidirectional applanation device (Ocular Response Analyzer) and dynamic Scheimpflug analyzer instruments (Corvis ST) have demonstrated the ability to quantify even subtle biomechanical differences in untreated KC corneas of different ectatic degree, and document the reduction in corneal hysteresis (CH) and corneal resistance factor (CRF) in situations where the corneal stiffness is reduced, such as after laser in situ keratomileusis and surface ablation procedures. It has also been possible to demonstrate an altered CH and CRF in patients with diabetes, smoking habit, glaucoma, Fuchs’ dystrophy, and corneal edema. It is puzzling that these diagnostic tools could document subtle biomechanical changes in these situations, yet fail to measure the purported changes induced by CXL on corneas with progressive KC. This failure to document significant and consistent biomechanical changes in corneal rigidity could suggest that CXL does not induce a simple reversal of the particular biomechanical deficits that characterize KC, or make the cornea significantly more resistant to bending forces as has been widely postulated. The absence of measurable biomechanical change in living KC corneas after CXL could be a consequence of biomechanical strengthening which is insignificant compared to the marked weakening caused by preexisting alteration of the collagen structure, disorganization of collagen fiber intertwining, and compromised structural–mechanical homogeneity that are hallmarks of keratoconic disease, especially in corneas with progressive KC. The changes in the cornea induced by CXL that have been described in vivo may instead be driven by a wound healing process in response to the removal of the corneal epithelial layer and subsequent exposure to riboflavin and ultraviolet-A (UVA). This paper will present evidence that sustains this hypothesis. How to cite this article Gatinel D. Reevaluating the Effect­iveness of Corneal Collagen Cross-linking and Its True Biomechanical Effect in Human Eyes. Int J Kerat Ect Cor Dis 2017;6(1):34-41.

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