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Kristensen MF, Frandsen Lau E, Schlafer S. Ratiometric imaging of extracellular pH in Streptococcus mutans biofilms exposed to different flow velocities and saliva film thicknesses. J Oral Microbiol 2021; 13:1949427. [PMID: 34349890 PMCID: PMC8291056 DOI: 10.1080/20002297.2021.1949427] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/23/2021] [Accepted: 06/25/2021] [Indexed: 11/22/2022] Open
Abstract
Introduction: Fluid flow has a prominent influence on the metabolism of surface-attached biofilms. Dental biofilms are covered by a thin saliva film that flows at different rates in different locations under stimulated and unstimulated conditions. Methods:The present study employed pH ratiometry to study the impact of different flow velocities, saliva film thicknesses and saliva concentrations on microscale pH developments in Streptococcus mutans biofilms of different age. Results:While saliva flow at a velocity of 0.8 mm/min (unstimulated flow) had little impact on biofilm pH, stimulated flow (8 mm/min; 80 mm/min) affected vertical pH gradients in the biofilms and raised the average pH in 48-h biofilms, but not in 72-h and 168-h biofilms. The saliva film thickness had a strong impact on biofilm pH under both static and dynamic conditions. pH drops were significantly higher in biofilms exposed to a thin saliva film (≤ 50 µm) than a thick saliva film (> 50 µm). pH drops in the biofilms were also strongly dependent on the saliva concentration and thus the buffer capacity of the salivary medium. For 48-h and 72-h biofilms, but not for 168-h biofilms, pH drops in distinct microenvironments were more pronounced when the local biofilm thickness was high.
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Affiliation(s)
| | - Ellen Frandsen Lau
- Section for Periodontology, Department of Dentistry and Oral Health, Aarhus University, Aarhus, Denmark
| | - Sebastian Schlafer
- Department of Dentistry and oral health, Aarhus University, Aarhus, Denmark
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Shirasawa H, Kumagai J, Sato E, Kabashima K, Kumazawa Y, Sato W, Miura H, Nakamura R, Nanjo H, Minamiya Y, Akagami Y, Terada Y. Novel method for immunofluorescence staining of mammalian eggs using non-contact alternating-current electric-field mixing of microdroplets. Sci Rep 2015; 5:15371. [PMID: 26477850 PMCID: PMC4609987 DOI: 10.1038/srep15371] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 09/24/2015] [Indexed: 02/06/2023] Open
Abstract
Recently, a new technique was developed for non-catalytically mixing microdroplets. In this method, an alternating-current (AC) electric field is used to promote the antigen–antibody reaction within the microdroplet. Previously, this technique has only been applied to histological examinations of flat structures, such as surgical specimens. In this study, we applied this technique for the first time to immunofluorescence staining of three-dimensional structures, specifically, mammalian eggs. We diluted an antibody against microtubules from 1:1,000 to 1:16,000, and compared the chromatic degree and extent of fading across dilutions. In addition, we varied the frequency of AC electric-field mixing from 5 Hz to 46 Hz and evaluated the effect on microtubule staining. Microtubules were more strongly stained after AC electric-field mixing for only 5 minutes, even when the concentration of primary antibody was 10 times lower than in conventional methods. AC electric-field mixing also alleviated microtubule fading. At all frequencies tested, AC electric-field mixing resulted in stronger microtubule staining than in controls. There was no clear difference in a microtubule staining between frequencies. These results suggest that the novel method could reduce antibody consumption and shorten immunofluorescence staining time.
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Affiliation(s)
- Hiromitsu Shirasawa
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | - Jin Kumagai
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | - Emiko Sato
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | - Katsuya Kabashima
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | - Yukiyo Kumazawa
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | - Wataru Sato
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | - Hiroshi Miura
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
| | | | - Hiroshi Nanjo
- Division of Clinical Pathology, Akita University Graduate School of Medicine, Akita, Japan
| | - Yoshihiro Minamiya
- Department of Thoracic Surgery, Akita University Graduate School of Medicine, Akita, Japan
| | | | - Yukihiro Terada
- Department of Obstetrics and Gynecology, Akita University Graduate School of Medicine, Akita, Japan
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