Neuroprotective Effects by Nimodipine Treatment in the Experimental Global Ischemic Rat Model : Real Time Estimation of Glutamate

OBJECTIVE: Glutamate is a key excitatory neurotransmitter in the brain, and its excessive release plays a key role in the development of neuronal injury. In order to define the effect of nimodipine on glutamate release, we monitored extracellular glutamate release in real-time in a global ischemia rat model with eleven vessel occlusion. METHODS: Twelve rats were randomly divided into two groups: the ischemia group and the nimodipine treatment group. The changes of extracellular glutamate level were measured using microdialysis amperometric biosensor, in coincident with cerebral blood flow (CBF) and electroencephalogram. Nimodipine (0.025 microg/100 gm/min) was infused into lateral to the CBF probe, during the ischemic period. Also, we performed Nissl staining method to assess the neuroprotective effect of nimodipine. RESULTS: During the ischemic period, the mean maximum change in glutamate concentration was 133.22+/-2.57 microM in the ischemia group and 75.42+/-4.22 microM (p<0.001) in the group treated with nimodipine. The total amount of glutamate released was significantly different (p<0.001) between groups during the ischemic period. The %cell viability in hippocampus was 47.50+/-5.64 (p<0.005) in ischemia group, compared with sham group. But, the %cell viability in nimodipine treatment group was 95.46+/-6.60 in hippocampus (p<0.005). CONCLUSION: From the real-time monitoring and Nissl staining results, we suggest that the nimodipine treatment is responsible for the protection of the neuronal cell death through the suppression of extracellular glutamate release in the 11-VO global ischemia model of rat.

Surface roughness analysis of ceramic bracket slots using atomic force microscope / 대한치과교정학회지

OBJECTIVE: This study was designed to measure the surface roughness at the slot floor of various ceramic brackets. METHODS: One kind of stainless steel bracket (Succes(R)), two kinds of monocrystalline brackets (Inspire Ice(R), Perfect(R)) and two kinds of polycrystalline brackets (Crystalline V(R), Invu(R)) were examined. Atomic force microscopy (AFM) was used to measure the surface roughness of each bracket. Data acquisition and processing were performed using SPIP(TM). RESULTS: The differences in values of Sa, Sq, and Sz in Invu(R) and Inspire Ice(R) were not statistically different from the control group Succes(R). The values of Sa, Sq, and Sz of Perfect(R) and Crystalline V(R) were greater than those of Succes(R). Differences of all the Sa, Sq, and Sz values between Perfect(R) and Crystalline V(R) were not statistically significant. CONCLUSIONS: It is concluded that the slot surfaces of Succes(R), Inspire Ice(R), and Invu(R) were smooth compared to those of Crystalline V(R) and Perfect(R).

Detection for demineralization of dental hard tissues using index-sequenced radiographs / 대한구강악안면방사선학회지

PURPOSE : The purpose of this study was to develop the radiographic technique for detecting the demineralization which is known as indication of dental caries MATERIALS AND METHODS : This technique was based on the comparing of multiple radiographs which was irradiated by multiple X-ray spectra. For the meaningful comparing, the multiple radiographs were reconstructed to the dosimetrically consistent images using a standard material. The difference of resulting images of same target with multiple spectra represents the difference of response of material as regards the spectra. RESULTS : We have found about 10% of demineralization of dental hard tissues particularly in the proximal region through the analyzing of differences. CONCLUSION : Most intriguing thing in this investigation was that the method to analyze difference shows us to an anatomic structure of dental hard tissues even if absolute values of optical density were excluded during the procedures.

Detection method of proximal caries using line profile in digital intra-oral radiography / 대한구강악안면방사선학회지

PURPOSE: The purpose of this study was to investigate how to detect proximal caries using line profile and validate linear measurements of proximal caries lesions by basic digital manipulation of radiographic images. MATERIALS AND METHODS: The X-ray images of control group (15) and caries teeth (15) from patients were used. For each image, the line profile at the proximal caries-susceptible zone was calculated. To evaluate the contrast as a function of line profile to detect proximal caries, a difference coefficient (D) that indicates the relative difference between caries and sound dentin or intact enamel was measured. RESULTS: Mean values of D were 0.0354+/-0.0155 in non-caries and 0.2632+/-0.0982 in caries (p<0.001). CONCLUSION: The mean values of caries group were higher than non-caries group and there was correlation between proximal dental caries and D. It is demonstrated that the mean value of D from caries group was higher than that of control group. From the result, values of D possess great potentiality as a new detection parameter for proximal dental caries.

The Effect of Extracellular Glutamate Release on Repetitive Transient Ischemic Injury in Global Ischemia Model

During operations, neurosurgeons usually perform multiple temporary occlusions of parental artery, possibly resulting in the neuronal damage. It is generally thought that neuronal damage by cerebral ischemia is associated with extracellular concentrations of the excitatory amino acids. In this study, we measured the dynamics of extracellular glutamate release in 11 vessel occlusion (VO) model to compare between single occlusion and repeated transient occlusions within short interval. Changes in cerebral blood flow were monitored by laser-Doppler flowmetry simultaneously with cortical glutamate level measured by amperometric biosensor. From real time monitoring of glutamate release in 11 VO model, the change of extracellular glutamate level in repeated transient occlusion group was smaller than that of single occlusion group, and the onset time of glutamate release in the second ischemic episode of repeated occlusion group was delayed compared to the first ischemic episode which was similar to that of single 10 min ischemic episode. These results suggested that repeated transient occlusion induces less glutamate release from neuronal cell than single occlusion, and the delayed onset time of glutamate release is attributed to endogeneous protective mechanism of ischemic tolerance.

Proximal caries detection using digital subtraction radiography in the artificial caries activity model / 대한구강악안면방사선학회지

PURPOSE: The purpose of the experiment was to evaluating the diagnostic ability of dental caries detection using digital subtraction in the artificial caries activity model. MATERIALS AND METHODS: Digital radiographies of five teeth with 8 proximal surfaces were obtained by CCD sensor (Kodak RVG 6100 using a size #2). The digital radiographic images and subtraction images from artificial proximal caries were examined and interpreted. In this study, we proposed novel caries detection method which could diagnose the dental proximal caries from single digital radiographic image. RESULTS: In artificial caries activity model, the range of lesional depth was 572-1,374 micrometer and the range of lesional area was 36.95-138.52mm2. The lesional depth and the area were significantly increased with demineralization time (p<0.001). Furthermore, the proximal caries detection using digital subtraction radiography showed high detection rate compared to the proximal caries examination using simple digital radiograph. CONCLUSION: The results demonstrated that the digital subtraction radiography from single radiographic image of artificial caries was highly efficient in the detection of dental caries compared to the data from simple digital radiograph.

Optimization of Wet Fixation Methods for AFM Imaging of Human Fibroblast Cells

We investigated the effect by the chemical fixative on human fibroblast cells (HFCs) in order to make nano-scale images using by the atomic force microscopy (AFM). The cell fixation needed to be optimized as prerequisite step for the preparation before analysis. AFM imaging after optimal wet fixation can provide practical, simple and fast technique for scanning living cells. In this study, AFM images - topography and amplitude - and the optic images of HFCs which were fixed with phosphate buffered saline (PBS), 2:1 ethanol:acetic acid, 4% glutaraldehyde and 37% formaldehyde were compared respectively. The final effect by washing with PBS or distilled water (D.W.) was examined after 4% glutaraldehyde fixation. To determine the optimal fixation method for HFCs, we performed quantitative and qualitative analysis by the height profile, the presence of artifacts and the morphology of well-conserved fibroblastic topography image by AFM. From AFM image which showed fibroblastic cellular morphology and differential height value of cytoplasm (670+/-47 nm, n=10) and nucleus (847+/-32 nm, n=10) in HFCs, we proposed that wet fixation by 4% glutaraldehyde, followed by final washing with PBS, could be the most suitable preparation for AFM imaging of HFCs, which enable us to approach easily on living cells with the least shrinkage.