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Articles by Z.H.A. Rahim
Total Records ( 5 ) for Z.H.A. Rahim
  T. Nalina and Z.H.A. Rahim
  In this study, the antimicrobial influence of crude aqueous extract of Piper betle L. on Streptococcus mutans (S. mutans) was investigated. The focus of the antimicrobial effects includes the ultrastructure and acid producing properties of S. mutans. Transmission electron microscopy (TEM) was used to determine the effect of the extract on the ultrastructure of S. mutans. Analysis of the effect on the acid producing properties was analyzed by pH drop assay. The investigation was further carried out to determine the possible chemical components of the extract using thin layer chromatography (TLC), bioautography and gas chromatography mass spectrometry (GCMS). From the micrographs of the transmission electron, it was found that the crude extract of Piper betle L. leaves causes plasma cell membrane damage and coagulation of the nucleoid. The extract was found to significantly reduce acid producing properties of the bacteria. Chemical analysis of the extract showed that hydroxychavicol, fatty acids (stearic and palmitic) and hydroxy fatty acid esters (stearic, palmitic and myristic) as the main components. It was suggested from the results obtained that the crude extract of Piper betle L. leaves may exert anticariogenic activities that are related to decrease in acid production and changes to the ultrastructure of S. mutans. Further study will be carried out to determine if the effect observed is attributed to the presence of hydroxychavicol, fatty acids and hydroxy fatty acid esters in the extract.
  K. Jessie , O.H. Hashim and Z.H.A. Rahim
  Precipitants for salivary proteins and rehydration buffers for two-dimensional electrophoresis (2-DE) analysis were, respectively compared and evaluated. Five different protein precipitants: TCA, TCA-acetone-DTT, TCA-acetone-mercaptoethanol, acetone and alcohol were used to precipitate proteins of the saliva samples. The efficiency of the precipitants was evaluated from protein content of the precipitate reflecting protein recovery. The precipitate with the highest protein content was subsequently solubilized using different rehydration buffers (RB1, RB2, RB3 and RB4) before being subjected to the 2-DE. The efficiency of the different rehydration buffers was compared with respect to the resolution and focusing time taken to attain the maximum voltage. Each of the saliva samples was subjected to the above experiments, carried out in triplicates. The precipitant containing TCA-acetone-DTT exhibited the highest protein recovery (82.2%) demonstrating significant difference when compared with the other precipitants (p<0.05). The RB4 containing DTT (reducing agent) and 0.5% IPG buffer 3-10 non-linear (carrier ampholyte) exhibited more protein spots indicating better separation resolution. The results obtained suggested that protein recovery depends on the precipitant used in the precipitation and resolution of proteins separation is influenced by the reducing agent and the ampholyte used in the rehydration buffer.
  W.I. Wan Nordini Hasnor , A.R. Fathilah , M. Md. Yusoff and Z.H.A. Rahim
  The objective of this study was to investigate and compare the adhering capacity of early colonizers of oral biofilm in a dynamic environment. The study was carried out by inoculating the early colonisers of oral biofilm (Streptococcus mitis, Streptococcus sanguinis and Actinomyces sp.) singly and in a mixture to the experimental pellicle in an artificial mouth (NAM) model for 24 h. This will form the respective 24 h single- and mixed-species biofilm. The bacterial population adhering to the experimental pellicle was determined and expressed as colony forming unit per ml (cfu mL-1). The adhered bacterial population was further confirmed using the Scanning Electron Microscope. It was found that S. mitis demonstrated maximum adherence (1153.33±132.46x104 cfu mL-1), followed by S. sanguinis (183.00±10.33x104 cfu mL-1) and by Actinomyces sp. (42.33±3.20x104 cfu mL-1). The adhering capacity of bacteria when present in a mixture of two-species was found to be reduced. However in a mixture of three species, it was found that the bacterial adherence was slightly increased. The difference in the adherence capacity of these bacteria to the experimental pellicle was found to be statistically significant (p<0.05). The results obtained in this study suggest that selected oral bacteria behave differently in a single- and mixed species biofilms.
  A.R. Fathilah , Z.H.A. Rahim , Y. Othman and M. Yusoff
  In this study, the bacteriostatic effect of Piper betle and Psidium guajava extracs on selected early dental plaque bacteria was investigated based on changes in the   doubling time (g) and  specific growth rates (μ). Streptococcus sanguinis, Streptococcus mitis and Actinomyces sp. were cultured in Brain Heart Infusion (BHI) in the presence and absence of the extracts. The growth of bacteria was monitored periodically every 15 min over a period of 9 h to allow for a complete growth cycle. Growth profiles of the bacteria in the presence of the extracts were compared to those in the absence and deviation in the g and μ were determined and analyzed. It was found that the g and μ were affected by both extracts. At 4 mg mL-1 of P. betle the g-values for S. sanguinis and S. mitis were increased by 12.0- and 10.4-fold, respectively (p<0.05). At similar concentration P. guajava increased the g-value by 1.8- and 2.6 -fold, respectively (p<0.05). The effect on Actinomyces sp. was observed at a much lower magnitude. It appears that P. betle and P. guajava extracts have bacteriostatic effect on the plaque bacteria by creating a stressed environment that had suppressed the growth and propagation of the cells. Within the context of the dental plaque, this would ensure the attainment of thin and healthy plaque. Thus, decoctions of these plants would be suitable if used in the control of dental plaque.
  Z.H.A. Rahim , A.R. Fathilah , S. Irwan and W.I. Wan Nordini Hasnor
  The objective of this study was to validate NAM model, an artificial mouth system for use in the study of oral biofilms. The NAM model consists of a cylindrical glass chamber (1x6 cm) which was used to mimic the oral cavity and glass beads (3 mm), placed along its length to provide surfaces for biofilm formation. The opening at both ends of the chamber which were fitted with rubber tubing served as an inlet to and outlet from the system. The two tubing were then connected to a reservoir (bacterial reservoir) via a peristaltic pump. The apparatus was kept at 37°C in a water bath. In the formation of oral biofilm, saliva was first pumped into the system to coat the glass beads. Excess saliva was then rinsed with distilled deionised water. Bacterial inoculum (Strep. mutans) was then allowed to flow into the system for 24 h. The bacterial population (cfu mL-1) in the biofilm developed on each of the glass beads in different experiments were analyzed and, validated for reproducibility. Its efficiency in maintaining temperature and flow rate for the experiment and sterility prior to the experiment was also determined. The results obtained showed that the bacterial counts of the biofilms between glass beads are not significantly different (p>0.6) and demonstrated reproducibility (4-5% standard deviation) between different experiments. It was also observed that the flow rate and temperature are constant and sterility of the apparatus is maintained throughout the experiment. This shows that the NAM model is valid for use in the in vitro study of oral biofilm development.
 
 
 
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