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Giblin J, Kura S, Nunuez JLU, Zhang J, Kureli G, Jiang J, Boas DA, Chen IA. High throughput detection of capillary stalling events with Bessel beam two-photon microscopy. Neurophotonics 2023; 10:035009. [PMID: 37705938 PMCID: PMC10495839 DOI: 10.1117/1.nph.10.3.035009] [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] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/09/2023] [Accepted: 08/17/2023] [Indexed: 09/15/2023]
Abstract
Significance Brief disruptions in capillary flow, commonly referred to as capillary "stalling," have gained interest recently for their potential role in disrupting cerebral blood flow and oxygen delivery. Approaches to studying this phenomenon have been hindered by limited volumetric imaging rates and cumbersome manual analysis. The ability to precisely and efficiently quantify the dynamics of these events will be key in understanding their potential role in stroke and neurodegenerative diseases, such as Alzheimer's disease. Aim Our study aimed to demonstrate that the fast volumetric imaging rates offered by Bessel beam two-photon microscopy combined with improved data analysis throughput allows for faster and more precise measurement of capillary stall dynamics. Results We found that while our analysis approach was unable to achieve full automation, we were able to cut analysis time in half while also finding stalling events that were missed in traditional blind manual analysis. The resulting data showed that our Bessel beam system was captured more stalling events compared to optical coherence tomography, particularly shorter stalling events. We then compare differences in stall dynamics between a young and old group of mice as well as a demonstrate changes in stalling before and after photothrombotic model of stroke. Finally, we also demonstrate the ability to monitor arteriole dynamics alongside stall dynamics. Conclusions Bessel beam two-photon microscopy combined with high throughput analysis is a powerful tool for studying capillary stalling due to its ability to monitor hundreds of capillaries simultaneously at high frame rates.
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Affiliation(s)
- John Giblin
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Sreekanth Kura
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Juan Luis Ugarte Nunuez
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Juncheng Zhang
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Gulce Kureli
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - John Jiang
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - David A. Boas
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
| | - Ichun A. Chen
- Boston University, Department of Biomedical Engineering, Boston, Massachusetts, United States
- Boston University, Neurophotonics Center, Boston, Massachusetts, United States
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Giblin JT, Park SW, Jiang J, Kılıç K, Kura S, Tang J, Boas DA, Chen IA. Measuring capillary flow dynamics using interlaced two-photon volumetric scanning. J Cereb Blood Flow Metab 2023; 43:595-609. [PMID: 36495178 PMCID: PMC10063827 DOI: 10.1177/0271678x221145091] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Two photon microscopy and optical coherence tomography (OCT) are two standard methods for measuring flow speeds of red blood cells in microvessels, particularly in animal models. However, traditional two photon microscopy lacks the depth of field to adequately capture the full volumetric complexity of the cerebral microvasculature and OCT lacks the specificity offered by fluorescent labeling. In addition, the traditional raster scanning technique utilized in both modalities requires a balance of image frame rate and field of view, which severely limits the study of RBC velocities in the microvascular network. Here, we overcome this by using a custom two photon system with an axicon based Bessel beam to obtain volumetric images of the microvascular network with fluorescent specificity. We combine this with a novel scan pattern that generates pairs of frames with short time delay sufficient for tracking red blood cell flow in capillaries. We track RBC flow speeds in 10 or more capillaries simultaneously at 1 Hz in a 237 µm × 237 µm × 120 µm volume and quantified both their spatial and temporal variability in speed. We also demonstrate the ability to track flow speed changes around stalls in capillary flow and measure to 300 µm in depth.
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Affiliation(s)
- John T Giblin
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Seong-Wook Park
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - John Jiang
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Kıvılcım Kılıç
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Sreekanth Kura
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Jianbo Tang
- Department of Biomedical Engineering, Southern University of Science and Technology, Shenzhen, China
| | - David A Boas
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
| | - Ichun A Chen
- Neurophotonics Center, Department of Biomedical Engineering, Boston University, Boston, MA, USA
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Kast P, Grisostomi C, Chen IA, Li S, Krengel U, Xue Y, Hilvert D. A strategically positioned cation is crucial for efficient catalysis by chorismate mutase. J Biol Chem 2000; 275:36832-8. [PMID: 10960481 DOI: 10.1074/jbc.m006351200] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Combinatorial mutagenesis and in vivo selection experiments previously afforded functional variants of the AroH class Bacillus subtilis chorismate mutase lacking the otherwise highly conserved active site residue Arg(90). Here, we present a detailed kinetic and crystallographic study of several such variants. Removing the arginine side chain (R90G and R90A) reduced catalytic efficiency by more than 5 orders of magnitude. Reintroducing a positive charge to the active site through lysine substitutions restored more than a factor of a thousand in k(cat). Remarkably, the lysine could be placed at position 90 or at the more remote position 88 provided a sterically suitable residue was present at the partner site. Crystal structures of the double mutants C88S/R90K and C88K/R90S show that the lysine adopts an extended conformation that would place its epsilon-ammonium group within hydrogen-bonding distance of the ether oxygen of bound chorismate in the transition state. These results provide support for the hypothesis that developing negative charge in the highly polarized transition state is stabilized electrostatically by a strategically placed cation. The implications of this finding for the mechanism of all natural chorismate mutases and for the design of artificial catalysts are discussed.
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Affiliation(s)
- P Kast
- Departments of Chemistry and Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Sun CK, Chen IA, Chang LL, Liou YF. Molecular and epidemiologic study of multiresistant Escherichia coli infections in Kaohsiung area. Gaoxiong Yi Xue Ke Xue Za Zhi 1989; 5:540-7. [PMID: 2696794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Totally 70 Escherichia coli (E. coli) isolated strains from patients in Chang Gung Memorial Hospital, Kaohsiung Medical College affiliated Chung Ho Memorial Hospital and the Navy General Hospital of the Republic of China, all in Kaohsiung, were collected during the period of July 1986-August 1987 and examined for their susceptibility to several antimicrobial agents as well as for their plasmid contents. The isolates tested showed a high level of resistance to ampicillin (Ap) (90.4%), piperacillin (Pip) (89.0%), tetracycline (Tc) (88.7%), streptomycin (Sm) (87.7%), chloramphenicol (Cm) (78.4%), kanamycin (Km) (72.6%) and sulfamethoxazole/trimethoprim (Sxt) (54.2%). Observations of the resistance patterns revealed that the dominant type was Ap-Tc-Cm-Sm-Pip-Km. The results of plasmid curing and transfer experiments indicated that three plasmids with molecular weights 49.2-51.6 Mdal, 69.8-178 Mdal and a third one with molecular weight larger than 178 Mdal carried resistance determinants for Gm-Nn, Sm-Km-Tc and Tc-Cm-Km, respectively.
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