1
|
Agyapong J, Rohrbach P. Quantifying pH in Malaria Using pHluorin and Flow Cytometry. Methods Mol Biol 2023; 2644:211-224. [PMID: 37142924 DOI: 10.1007/978-1-0716-3052-5_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Intracellular pH (pHi) plays a critical role in the regulation of numerous biological functions where specific pH ranges are required for optimal operation within cells. Slight pH changes can impact the regulation of diverse molecular processes, including enzymatic activities, ion channels, and transporters, which all play a role in cell functions. Methods for quantifying pHi continue to evolve and include various optical methods using fluorescent pH indicators. Here, we provide a protocol to measure pHi in the cytosol of Plasmodium falciparum blood stage parasites by means of flow cytometry and using pHluorin2, a pH-sensitive fluorescent protein that has been introduced into the genome of the parasite.
Collapse
Affiliation(s)
- Jeffrey Agyapong
- Institute of Parasitology, McGill University, Montreal, QC, Canada
| | - Petra Rohrbach
- Institute of Parasitology, McGill University, Montreal, QC, Canada.
| |
Collapse
|
2
|
Liu J, Liu H, Liu Q, Xu J, Liu X, Zheng H, Wu Y. Encoding capability prediction of acquisition schedules in CEST MR fingerprinting for pH quantification. Magn Reson Med 2021; 87:2044-2052. [PMID: 34752642 DOI: 10.1002/mrm.29074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 09/30/2021] [Accepted: 10/19/2021] [Indexed: 12/12/2022]
Abstract
PURPOSE To identify a reliable metric for predicting the encoding capability of CEST MR fingerprinting acquisition schedules for pH quantification, which may facilitate CEST MR fingerprinting protocol optimization. METHODS Numerical simulations and Cr phantom MRI experiments were conducted at 3 Tesla under representative CEST MR fingerprinting sampling scenarios, including the pseudorandomization of imaging parameters (e.g., saturation power B1 , saturation frequency offset, saturation time, and relaxation time), and variation of the maximum saturation power B1max , B1 number, and sampling pattern. The CEST effect at 2 ppm was measured using asymmetry analysis and matched to a predefined dictionary to determine the pH. The pH quantification error was assessed using RMSE. Three metrics, namely the Cramer-Rao bound, dot product, and Euclidean distance, were calculated for each sampling scenario, and their relationships with the pH RMSE were investigated to examine their effectiveness for predicting the encoding capability of sampling schedules for pH quantification. RESULTS Both simulation and phantom studies revealed that the Cramer-Rao bound metric consistently exhibited superior performance for predicting the pH quantification error. Although dot product exhibited good encoding capability prediction in most sampling scenarios, it failed in the scenario with varied B1 numbers. In contrast, Euclidean distance exhibited the worst performance among the 3 metrics in all scenarios. CONCLUSION Superior over dot product and Euclidean distance, the Cramer-Rao bound metric may reliably predicting the encoding capability of CEST MR fingerprinting sampling strategies and may be useful for guiding CEST MRI protocol optimization.
Collapse
Affiliation(s)
- Jie Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China.,Key Laboratory of Health Informatics, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China
| | - Hui Liu
- UIH America Inc., Houston, Texas, USA
| | - Qi Liu
- UIH America Inc., Houston, Texas, USA
| | - Jian Xu
- UIH America Inc., Houston, Texas, USA
| | - Xin Liu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China.,Key Laboratory of Health Informatics, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China
| | - Hairong Zheng
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China.,Key Laboratory of Health Informatics, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China
| | - Yin Wu
- Paul C. Lauterbur Research Center for Biomedical Imaging, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China.,Key Laboratory of Health Informatics, Chinese Academy of Sciences, Shenzhen, Guangdong, People's Republic of China
| |
Collapse
|
3
|
Abstract
Extracellular pH is important in clinical measurements due to its correlation to cell metabolism and disease progression. In MRI, T1/T2 ratiometric analysis and other methods have been previously applied to quantify pH using conventional pulse sequences. However, for nanoparticle-based approaches, heterogeneity in size and surface functionalization tends toward qualitative rather than quantitative results. To address this limitation, we developed a novel DNA-based MRI contrast agent, pH-DMRCA, which utilizes a highly programmable and reproducible nanostructure. The pH-DMRCA is a dendritic DNA scaffold that is functionalized with a pH-responsive MRI-sensitive construct, Gd(NP-DO3A), at the end of each DNA arm. We first evaluated the r1 and r2 response of our pH-DMRCA over a range of pH values (pH = 5-9) to establish a relaxometric model of pH. These MRI-based assessments of pH were validated in a separate set of samples using a pH electrode (n = 18) and resulted in a good linear correlation (R2 = 0.99, slope = 0.98, intercept = 0). A Bland-Altman analysis of the results also showed reasonable agreement between the calculated pH and measured pH. Moreover, these pH comparisons were consistent across three different pH-DMRCA concentrations, demonstrating concentration-independence of the method. This MRI-based pH quantification methodology was further verified in human blood plasma. Given the versatility of the DNA-based nanostructures, the contrast agent has a potential to be applied to a wide variety of imaging applications where extracellular pH is important including cancer, stroke, cardiovascular disease, and other important diseases.
Collapse
Affiliation(s)
- Hyewon Seo
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Kristine Y. Ma
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Erin E. Tuttle
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| | - Isen Andrew C. Calderon
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Alissa D. Buskermolen
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
| | - Chris A. Flask
- Departments of Radiology, Biomedical Engineering, and Pediatrics, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Heather A. Clark
- Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, United States
- Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts 02115, United States
| |
Collapse
|
4
|
Abstract
Many eukaryotic cells ingest extracellular particles in a process termed phagocytosis which entails the generation of a new intracellular compartment, the phagosome. Phagosomes change their composition over time and this maturation process culminates in their fusion with acidic, hydrolase-rich lysosomes. During the maturation process, degradation and, when applicable, killing of the cargo may ensue. Many of the events that are pathologically relevant depend on strong acidification of phagosomes by the 'vacuolar' ATPase (V-ATPase). This protein complex acidifies the lumen of some intracellular compartments at the expense of ATP hydrolysis. We discuss here the roles and importance of V-ATPase in intracellular trafficking, its distribution, inhibition and activities, its role in the defense against microorganisms and the counteractivities of pathogens.
Collapse
Affiliation(s)
- Sandra Kissing
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany
| | - Paul Saftig
- Institut für Biochemie, Christian-Albrechts-Universität zu Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany.
| | - Albert Haas
- Institut für Zellbiologie, Friedrich-Wilhelms-Universität Bonn, Ulrich-Haberland-Str. 61A, D-53121 Bonn, Germany.
| |
Collapse
|