We demonstrate fluorescence imaging by two-photon excitation without scanning in biological specimens as previously described by Hwang and co-workers, but with an increased field size and with framing rates of up to 100 Hz. During recordings of synaptically-driven Ca2+ events in primary rat hippocampal neurone cultures loaded with the fluorescent Ca2+ indicator Fluo-4 AM, we have observed greatly reduced photo-bleaching in comparison with single-photon excitation. This method, which requires no costly additions to the microscope, promises to be useful for work where high time-resolution is required.

Summary This study investigated the probiotic characteristics of lactic acid bacteria (LAB) isolated from 14 Malaysian fermented food or milk products. In total, 22.3% (121 of 542) of the LAB isolated from the local fermented products exhibited antibacterial activity against Micrococcus luteus. Twelve LAB that demonstrated better antibacterial activity against M. luteus as compared to a commercial strain Lactobacillus casei strain Shirota (LABPC) were selected for further characterisation. Based on 16S rRNA gene sequence, the LAB were identified as pediococci (seven) and lactobacilli (five). All 12 LAB showed bile tolerance, but only eight were acid tolerant at pH ≥ 3.0. The highest level of adhesion to HT‐29 cells was observed among the Lactobacillus sp. LAB 1 and 10. The LAB also showed antimicrobial activity against Escherichia coli and Staphylococcus aureus through the production of organic acids. LAB isolated from Malaysian fermented food and milk products, especially fermented tapioca, contains potential probiotic candidates.

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Background. Acmella paniculata has been used as a traditional medicine to treat oral health diseases such as dental caries and periodontitis. Streptococcus mutans is a common bacterium that initiates dental caries at an early stage. Aim. The aim of this study was to determine the mode of action of A. paniculata (extracts) against S. mutans growth. Methods. Time-kill assay has been done to investigate the rate of kill and effectiveness of Acmella paniculata (AP) extracts against S. mutans growth. Phytochemical analysis was done to identify major compounds in AP extracts using gas chromatography mass spectrometry (GCMS). Scanning and transmission electron microscopy (SEM and TEM) have been done to observe the morphological changes of treated bacteria. Transcriptomic profile analysis has been done using Next Gene Sequencing. Results. AP flower n-hexane (APFH) and AP flower dichloromethane (APFD) extracts acted as bactericidal agents after killing >3 log10 cfu/mL of S. mutans after 24 hours. Oleic and hexadecenoic acids were found to be the major compounds in APFD and APFH extracts, respectively. Photomicrographs from SEM and TEM of treated S. mutans show that the bacterial cell wall has been lysed and the cytoplasm content was decreased. Pathway analysis revealed that the APFD extract significantly affected biosynthesis peptidoglycan, gene expression, RNA processing, and macromolecule metabolism processes in S. mutans. Conclusion. Data analysis revealed that multiple mechanisms of action were involved in antibacterial activity of A. paniculata extracts toward S. mutans.

The understanding and capability to simulate reproducible in vitro plaque model are important where this artificial plaque can be utilized as a tool in assessing the efficacy of tooth cleaning products. Previous studies were done on synthetic surfaces such as glass beads under a very strict, controlled environment. Thus, the aim of this study was to establish a simplified system to enable the formation of single species biofilm on the extracted natural tooth as plaque model. Healthy extracted natural tooth was incubated in broth mixture of Streptococcus mutans, containing 5% sucrose and stimulated saliva in a simplified system. The incubation was set at room temperature for 24, 48, and 72 hours. After 24 hours, the sticky deposit was formed on the surface of the tooth. The area of biofilm, stained with disclosing agent, expended from 19.05 ± 1.41 mm 2 (24 hours) to 23.25 ± 0.35 mm 2 (48 hours). However, no significant expansion of the plaque area was observed on 72 hours (23.83 ± 0.52 mm 2 ). The biofilm was then observed under Infinite Focus Microscope (IFM) to measure the biofilm thickness. The preliminary attempt showed that plaque appeared as dark deposit with a certain thickness. Therefore, this simplified system is a reliable method for producing artificial plaque.