Biomedical subjects

Hyeong-Cheol Yang

Publications and source records attributed to Hyeong-Cheol Yang.

At least 19 recordsLinked to original sources

PubMed2007

Changes in scattering and absorption properties of esthetic filling materials after aging.

OBJECTIVES: Assuming that color changes after aging are related to changes in translucency of materials, the purpose of the present study was to determine the correlation between the changes in color and the changes in scattering and absorption properties after accelerated aging with representative dental esthetic restorative materials: glass ionomer, resin-modified glass ionomer, compomer, and resin composite. METHODS: Color was measured according to the CIELAB color scale in the transmittance and reflectance modes and used to calculate changes in color (deltaE*(ab)), color coordinates (deltaL*, delta a*, and delta b*), translucency parameter (deltaTP), scattering coefficient (deltaS), absorption coefficient (deltaK), and light reflectivity (deltaRI) after accelerated aging. Simple correlations between each pair of the changes in optical values were calculated, and multiple regression analysis was used to determine the parameters influencing the changes in color and color coordinates (p = 0.05). RESULTS: In the resin composite and compomer, deltaS, deltaK, and deltaRI values were approximately zero, whereas deltaS was as high as 8.9 in the glass ionomer. For most comparisons, correlation coefficient (r) was between 0.700 and 0.997. DeltaL* was found to have a major influence on color changes, and deltaS, deltaTP, and deltaRI influenced deltaL*. Therefore, changes in scattering and absorption properties, after aging, were closely correlated with changes in color and color coordinates, especially in glass ionomer-based filling materials.

Acrylic Resins↗

PubMed2006

Metameric effect between dental porcelain and porcelain repairing resin composite.

OBJECTIVES: The objectives were to evaluate the metameric color and hue angle (degrees) changes between dental porcelain and porcelain repairing resin composites. METHODS: Color of three shades (A2, A3, A3.5) of one brand of dental porcelain and three original shades (A2, A3, A3.5) and three combinations (A2-A3, A3-3.5, A2-A3.5) of three brands of porcelain repairing resin composites (ABT, FSP, TCR) were measured relative to the three standard illuminants (D65, A and F2). Specimen was 2mm in thickness, and 1mm of each shade was layered to make combined shades. Color differences (DeltaEab*) between each shade of dental porcelain and repairing resin composites relative to the three illuminants were calculated, and the ratios of color difference (modified metamerism index) by the change of illuminant were calculated. The ratios of hue angle changes were also compared. RESULTS: Differences in modified metamerism index and the ratio of hue angle changes were influenced by the porcelain shade, brand of resin composites and shade of resin composites. In all three brands of resin composites, A3.5 shade showed the smallest values in modified metamerism index regardless of the shade of porcelain. The average ratio of hue angle changes between each porcelain shade and all the shades of each resin composites showed similar trend when illuminant was changed from D65 to F2. SIGNIFICANCE: Metameric effect between dental porcelain and repairing resin composites varied depending on the shade of porcelain, brand of resin composite and the illuminant. Therefore, shade matching between porcelain and repairing resin composite should be performed carefully. This study confirmed that shades should be matched under the light corresponding to that of use.

Analysis of Variance↗

PubMed2006

Involvement of oxidative stress in mutagenicity and apoptosis caused by dental resin monomers in cell cultures.

OBJECTIVE: This investigation studied the possibility that apoptosis as well as mutagenicity induced by resin monomers are mediated by oxidative stress. METHODS: A range of dilutions of three resin monomers (GMA, TEGDMA, and HEMA) was added to culture medium (DMEM/10% FBS), of V79-4 fibroblasts and RPC-C2A pulp cells for 24 h. Their cytotoxic effects were measured by a colorimetric functional assay (MTT). Chromosomal aberration induced by the resin monomers was investigated by counting micronuclei in V79-4 cells. The effects of the resin monomers on DNA fragmentation were viewed by agarose gel electrophoresis of DNA, isolated from RPC-C2A pulp cells that were treated by resin compounds. Resin monomer-induced apoptosis was further confirmed by flow cytometry (staining with both annexin V-FITC and PI). RESULTS: All monomers exhibited a dose-dependent cytotoxic effect, and the ranking of the cytotoxicity based on TC50 was GMA > TEGDMA > HEMA. The resin monomer-induced cytotoxicity was significantly decreased by co-treatment with N-acetylcystein (NAC), an antioxidant. The authors also confirmed a dose-dependent genotoxicity of the resin monomers that had induced micronucleated cells in V79-4 fibroblasts. Similar to the effects on cytotoxicity, NAC reduced the numbers of micronuclei in comparison with those generated by the resin monomers. The preventive effects of NAC were also observed in monomer-induced apoptosis in RPC-C2A cells. A DNA ladder pattern, characteristic of apoptosis, was shown at cytotoxic concentrations, but NAC blocked the resin monomer-mediated DNA fragmentation. The preventive effects of NAC on apoptosis were confirmed by Annexin V staining. Cells exposed to 300 microM GMA, 7 mM TEGDMA, or 14 mM HEMA for 24 h showed a significant increase in apoptotic cells, while NAC co-treatment caused a reduction in apoptotic cells compared to controls. SIGNIFICANCE: These findings suggest that glutathione depletion and oxidative stress are responsible for GMA, TEGDMA, and HEMA-induced mutagenicity and apoptosis.

Animals↗

PubMed2006

Difference in color and color parameters between dental porcelain and porcelain-repairing resin composite.

The objective of this study was to measure the differences in color and color parameters between dental porcelain and porcelain-repairing resin composites. The colors of three shades (A2, A3, A3.5) of one brand of dental porcelain, three original shades (A2, A3, A3.5), and three combinations (A2/A3, A3/3.5, A2/A3.5) of three brands of porcelain-repairing resin composites (ABT, FSP, TCR) were measured. The specimens were 2 mm thick, and 1 mm of each shade was layered to make combined shades. Differences in color (DeltaE(ab) (*)), lightness (DeltaL*), chroma (DeltaC(ab) (*)), and hue (DeltaH(*)) between porcelain and resin composite were calculated. Color difference was calculated as DeltaE(ab) (*) = (DeltaL*(2) + Deltaa*(2) + Deltab*(2))(1/2), chroma difference was calculated as DeltaC(ab) (*) = (Deltaa*(2) + Deltab*(2))(1/2), and hue difference was calculated as DeltaH(ab) (*) = (DeltaE(ab) (*2) - DeltaL*(2) - DeltaC(ab) (*2))(1/2). The influence of porcelain shade, brand of resin composites, and shade of resin composites were analyzed by three-way analyses of variance, and the differential influence of color parameters on color difference was analyzed with multiple regression analysis (alpha = 0.05). Differences in color and color parameters were influenced by the porcelain shade, brand and shade of resin composites. The DeltaE(ab) (*) value was in the range of 2.2-16.9. The DeltaE(ab) (*) value was correlated with DeltaC(ab) (*) (standardized correlation coefficient, beta = - 0.85), DeltaL* (beta = - 0.52), and DeltaH(ab) (*) (beta = 0.08). Between the same shade designated pairs of porcelain and repairing composite, color difference was perceptible. Therefore, studies to improve the color matching between porcelain and repairing resin are recommended.

Color↗

PubMed2006

Changes in color and translucency of porcelain-repairing resin composites after thermocycling.

The objective of this study was to determine the changes in color and translucency of dental porcelain-repairing resin composites compared to dental porcelain after thermocycling. Color and spectral reflectance of three shades (A2, A3, and A3.5) of one brand of dental porcelain and three basic shades (A2, A3, and A3.5) and three combinations (A2/A3, A3/3.5, and A2/A3.5) of three brands of porcelain-repairing resin composites (ABT, FSP, and TCR) were measured, before and after thermocycling for 3000 cycles, relative to the illuminant D65. The specimen was 2 mm in thickness, and 1 mm of each shade was layered to make combined shades. Changes in color (DeltaE*ab) and translucency parameter (DeltaTP) were calculated. A general linear model by the material (porcelain or resin composite) and shade was used to compare differences (alpha = 0.05). The range of color changes was 0.68-1.67 in porcelain, 0.56-1.30 in ABT, 2.28-3.10 in FSP, and 0.36-1.15 in TCR. The range of DeltaTP was 0.45-0.96 in porcelain, -0.48 to 0.94 in ABT, -1.31 to 0.82 in FSP, and -0.51 to 1.91 in TCR. After thermocycling, changes in color and TP were correlated with the shade of the material, but not with the material. The discrepancy in the changes of color and translucency after thermocycling between porcelain and porcelain-repairing resin composites should be considered when selecting repairing materials.

Color↗

PubMed2006

Chemotactic migration of human mesenchymal stem cells and MC3T3-E1 osteoblast-like cells induced by COS-7 cell line expressing rhBMP-7.

During bone development, remodeling, and repair, bone morphogenetic proteins (BMPs) induce the differentiation of mesenchymal progenitor cells (MPCs) that enter into the osteoblastic lineage, and enhance the recruitment of MPCs and osteogenic cells. The process of migration is believed to be regulated, in part, by growth factors stored within the bone matrix, which are released by bone resorption. In this study, primary human mesenchymal stem cells (hMSCs) and MC3T3-E1 osteoblasts were examined for chemotaxis in response to recombinant human BMP-7 (rhBMP-7) produced in COS-7 cells (co-culture system). In order to produce BMP-7 transfected cells (BTCs), which serve as suppliers of rhBMP-7 under in vitro culture conditions, the encoding DNA was transferred into the pTARGET expression vector and introduced into COS-7 cells by conventional genetic engineering techniques. In cell culture studies, the rhBMP-7 produced in BTCs stimulated the specific activity of ALP, the production of cAMP in response to PTH, and the synthesis of osteocalcin. Migration assays were conducted with a computer-aided time-lapse video-microscopy system, to allow the rapid and precise analysis of cell migration and for the dynamic measurement of cell position and morphology. The migration distance and speed of the MC3T3-E1 cells, or hMSCs, co-cultured with BTCs, using a band-type seeding method, were significantly increased (p < 0.001), compared to those of the MC3T3-E1 cells (or hMSCs) only. In conclusion, these studies revealed that rhBMP-7 plays a role in the migration of bone-forming cells, and that the co-culture model (co-culture of bone-forming cells with BMP-7-producing cells) using a computer-aided, time-lapse video-microscopy system, is useful for the chemotactic migration assay of other chemotactic growth factors.

3T3 Cells↗

PubMed2005

Mitochondrial movement and inheritance in budding yeast.

Mitochondria are essential organelles that perform fundamental cellular functions including aerobic energy mobilization, fatty acid oxidation, amino acid metabolism, heme biosynthesis and apoptosis. Mitochondria cannot be synthesized de novo. Therefore, the inheritance of this organelle is an essential part of the cell cycle; that is, daughter cells that do not inherit mitochondria will not survive. The budding yeast, Saccharomyces cerevisiae, is a facultative aerobe that can tolerate mitochondrial mutations that would be lethal in other organisms. Therefore, yeast has been used extensively to study inheritance and segregation of mitochondria. As a result, much of what we know regarding mitochondrial inheritance has been uncovered using yeast as a model system. Here, we describe the latest developments in mitochondrial motility and inheritance.

Actin-Related Protein 2-3 Complex↗

PubMed2005

Changes in surface characteristics of dental resin composites after polishing.

The objectives of this study were (1) to determine in vitro changes in surface roughness and color of dental resin composites after application of three finishing and polishing systems; (2) to evaluate the difference in color stability after immersion in a dye solution after polishing; and (3) to evaluate the effects of surface condition, especially roughness, on measured color depending on the color measuring geometries of specular component excluded (SCE) and specular component included (SCI). Color and surface roughness (R(a)) of resin composites of four brands of A2 shade and one brand of Yellow Enamel shade were measured after polymerization, after polishing with Enhance (Dentsply), Sof-Lex (3M ESPE), or Super-Snap (Shofu) composite finishing and polishing systems. Color was also measured after immersion in 2% methylene blue solution. Color was measured according to the CIELAB color scale. Color changes (DeltaE*(ab)) after polishing/staining and by the measuring geometry were calculated by the equation; DeltaE*(ab) = [(DeltaL*)(2) + (Deltaa*)(2) + (Deltab*)(2)](1/2). Ra value was measured with a surface roughness tester. DeltaE*(ab) and DeltaL* values after polishing and after staining varied among polishing systems when measured with SCE geometry. Composites polished with Super-Snap and Sof-Lex systems showed higher DeltaE*(ab) and DeltaL* values than those polished with Enhance polishing system with SCE geometry. DeltaE*(ab) and DeltaL* values between specimens with different surface conditions measured with SCE geometry were significantly higher than those with SCI (p < 0.01). Changes in R(a) value after polishing was insignificant in most cases.

Biocompatible Materials↗

PubMed2005

Quantitative analysis of the adhesion of cariogenic streptococci to orthodontic metal brackets.

The aim of this study was to analyze the adhesion of cariogenic streptococci to orthodontic metal brackets in terms of the type of bacterial strains, the incubation time, and saliva coating. Two strains of Streptococcus mutans (S. mutans LM7 and S. mutans OMZ65) and two strains of S. sobrinus (S. sobrinus B13 and S. sobrinus 6715) were used. Twenty metal brackets were incubated with either unstimulated whole saliva or phosphate-buffered saline for two hours. The bacterial adhesion assays were then performed by incubating the tritium-labeled streptococci with saliva-coated or noncoated orthodontic brackets for three, six, or nine hours. The results showed a characteristic binding pattern according to the type of bacterial strains used. S. mutans OMZ65 showed the highest amount of adhesion, whereas S. sobrinus B13 showed the lowest amount of adhesion. Generally, an extended incubation time increased the adhesion of cariogenic streptococci, and the amount of adhesion was the highest after nine hours of incubation. The saliva coating did not significantly influence the adhesion of bacteria. However, this saliva-mediated adhesion differed according to incubation time. The saliva coating tended to gradually decrease the adhesion by the extended incubation time, compared with the noncoated controls. This study indicates that each strain of cariogenic streptococci has a characteristic adhesion pattern and the type of bacterial strain, the incubation time, and saliva influenced the adhesion.

Adult↗

PubMed2005

Phosphoric acid incorporated with acidulated phosphate fluoride gel etchant effects on bracket bonding.

The aim of this study was to evaluate the effects of etching with phosphoric acid incorporated in an acidulated phosphate fluoride (APF) gel on the bonding of a bracket and the loss of sound enamel. In the control group, the enamel was etched with 37% phosphoric acid for 30 seconds. In the experimental groups, the enamel was etched for 30 seconds with 37% phosphoric acid blended with 1.23% APF gel at various ratios (25%, 33%, 50%, 67%, and 75% APF gel). The brackets were bonded with Transbond XT light-cured orthodontic adhesive according to the manufacturer's instructions. The specimens were then treated under three different conditions: 37 degrees C for one hour, 37 degrees C for 24 hours, and thermocycling (2500 times) between 5 degrees C and 55 degrees C in deionized water. The shear bond strength of 10 specimens in each condition was measured and the results analyzed using a Tukey multiple comparison test (P = .05). The shear bond strength decreased significantly as the fraction of the APF gel increased in the experimental etchant. An apparent increase in the adhesive remnant index score was also observed in the large fraction of the APF gel. To minimize the damage of the sound enamel surface during the etching and debonding procedures, a mixture of phosphoric acid and an APF gel (50% and 67% APF fraction) can be used as an phosphoric acid etchant substitute without loss of the proper bracket bond strength.

Acid Etching, Dental↗

PubMed2004

Live cell imaging of mitochondrial movement along actin cables in budding yeast.

BACKGROUND: Mitochondrial inheritance is essential for cell division. In budding yeast, mitochondrial movement from mother to daughter requires (1) actin cables, F-actin bundles that undergo retrograde movement during elongation from buds into mother cells; (2) the mitochore, a mitochondrial protein complex implicated in linking mitochondria to actin cables; and (3) Arp2/3 complex-mediated force generation on mitochondria. RESULTS: We observed three new classes of mitochondrial motility: anterograde movement at velocities of 0.2-0.33 microm/s, retrograde movement at velocities of 0.26-0.51 microm/s, and no net anterograde or retrograde movement. In all cases, motile mitochondria were associated with actin cables undergoing retrograde flow at velocities of 0.18-0.62 microm/s. Destabilization of actin cables or mutations of the mitochore blocked all mitochondrial movements. In contrast, mutations in the Arp2/3 complex affected anterograde but not retrograde mitochondrial movements. CONCLUSIONS: Actin cables are required for movement of mitochondria, secretory vesicles, mRNA, and spindle alignment elements in yeast. We provide the first direct evidence that one of the proposed cargos use actin cables as tracks. In the case of mitochondrial inheritance, anterograde movement drives transfer of the organelle from mothers to buds, while retrograde movement contributes to retention of the organelle in mother cells. Interaction of mitochondria with actin cables is required for anterograde and retrograde movement. In contrast, force generation on mitochondria is required only for anterograde movement. Finally, we propose a novel mechanism in which actin cables serve as "conveyor belts" that drive retrograde organelle movement.

Actins↗

PubMed2004

Evaluation of wear resistance of dental resin composites with a 3D profilometer.

The objectives of this study were to determine the wear resistance of dental resin composites, and to evaluate the influence of wear-simulating apparatus on wear. Nine commercial resin composites were studied. Wear was simulated with an oral wear simulator (Proto-Tech), which simultaneously incorporates the wear mechanism of attrition and abrasion in three-body wear mode, and with a pin-on-disk type friction tester (Rhesca, Japan). Composite specimens were subjected to 50,000 cycles of wear against a dental porcelain antagonist. After wear simulation, parameters for the determination of wear amount, such as wear volume, maximum wear depth, mean of maximum wear depth, and average wear depth were measured with the use of a 3D profilometer. For the oral wear simulator, the range of wear volume was 4.3-9.2 x 10(-2) mm3, and there were significant differences among the composites (p < 0.05). In other parameters, there were no significant differences among the composites. For the pin-on-disk tester, the range of mean of maximum wear depth was 7.5-26.3 microm, which was significantly different among the composites (p < 0.05). Correlation coefficient (r) between the wear volume from the oral wear simulator and the mean of maximum wear depth from the pin-on-disk tester was 0.52. Conclusively, dental resin composites showed significantly different wear resistance. Wear simulating apparatus influenced the amount of wear, and suitable parameters for the determination of wear amounts should be selected in each apparatus.

Composite Resins↗

PubMed2004

Live cell imaging of the assembly, disassembly, and actin cable-dependent movement of endosomes and actin patches in the budding yeast, Saccharomyces cerevisiae.

Using FM4-64 to label endosomes and Abp1p-GFP or Sac6p-GFP to label actin patches, we find that (1) endosomes colocalize with actin patches as they assemble at the bud cortex; (2) endosomes colocalize with actin patches as they undergo linear, retrograde movement from buds toward mother cells; and (3) actin patches interact with and disassemble at FM4-64-labeled internal compartments. We also show that retrograde flow of actin cables mediates retrograde actin patch movement. An Arp2/3 complex mutation decreases the frequency of cortical, nonlinear actin patch movements, but has no effect on the velocity of linear, retrograde actin patch movement. Rather, linear actin patch movement occurs at the same velocity and direction as the movement of actin cables. Moreover, actin patches require actin cables for retrograde movements and colocalize with actin cables as they undergo retrograde movement. Our studies support a mechanism whereby actin cables serve as "conveyor belts" for retrograde movement and delivery of actin patches/endosomes to FM4-64-labeled internal compartments.

Actin-Related Protein 2↗

PubMed2004

Changes of optical properties of dental nano-filled resin composites after curing and thermocycling.

The objective was to evaluate the color changes after curing, polishing, and thermocycling of a nano-filled resin composite. A nano-filled composite was grouped into two shades of enamel (EN) and translucent (TL). One hybrid composite was used as a control (CL). Color of specimens of 10 mm in diameter and 2 mm in thickness was measured on a reflection spectrophotometer with SCE geometry under the D65 illumination over white and black backgrounds. Color before curing and after curing, polishing and thermocycling was measured. Color change (DeltaE(*) (ab)), translucency parameter (TP), and contrast ratio (CR) were compared. Average DeltaE(*) (ab) after curing was 4.6 in the EN group and 10.4 in the TL group compare to 2.9 in CL. Polishing caused average DeltaE(*) (ab) of 3.3-3.6, which was not different by the shade group (p > 0.05). After 2000 cycles of thermocycling, average DeltaE(*) (ab) was 1.4-1.8, which was not different by the shade group (p > 0.05). TP values increased after curing in the EN group, but decreased in the TL group (p < 0.05). TP values after thermocycling decreased in the EN group but did not change in TL (p = 0.05). TP values of TL shades were higher than those of EN regardless of specimen conditions (p < 0.05). Changes in CR values showed similar trends to those of TP values in translucency. Changes of color and translucency after curing, polishing, and thermocycling varied by the shade group.

Composite Resins↗

PubMed2004

Effect of tooth-whitening strips and films on changes in color and surface roughness of resin composites.

Though the effectiveness of film and strip type tooth-whitening agents on the bleaching of tooth has been confirmed, there have been few studies on their influence on restorative materials. The purpose was to investigate the effect of tooth-whitening film and strip on the changes in color and surface roughness of dental resin composites. The composites used were Filtek Supreme (3M ESPE), Point 4 (Kerr), and Spectrum TPH (Dentsply). Specimens were prepared 10 mm in diameter and 1 mm in thickness. Film type (Night Effect, Crest; Simply White Night, Colgate) and strip type (Whitestrips Professional, Crest; Claren, LG) agents were used, and bleaching procedures were performed for 2 weeks according to the manufacturers' recommendations. Color was measured according to the CIELab color scale with a spectrophotometer. Color difference ( DeltaE(*)(ab)) and surface roughness ( Ra) were measured. After bleaching, the DeltaE(*)(ab) values were 0.90-1.67, which was too small to be perceptible (<3.3). The increase in Ra values was significant in some composite-whitening agent combinations ( P<0.01), however the value was less than 0.30 microm after bleaching. Therefore the change in surface roughness was clinically insignificant. We conclude that the influence of tooth-whitening film and strip on the color and surface roughness of dental resin composites was negligible.

Analysis of Variance↗

PubMed2004

A type V myosin (Myo2p) and a Rab-like G-protein (Ypt11p) are required for retention of newly inherited mitochondria in yeast cells during cell division.

Two actin-dependent force generators contribute to mitochondrial inheritance: Arp2/3 complex and the myosin V Myo2p (together with its Rab-like binding partner Ypt11p). We found that deletion of YPT11, reduction of the length of the Myo2p lever arm (myo2-Delta6IQ), or deletion of MYO4 (the other yeast myosin V), had no effect on mitochondrial morphology, colocalization of mitochondria with actin cables, or the velocity of bud-directed mitochondrial movement. In contrast, retention of mitochondria in the bud was compromised in YPT11 and MYO2 mutants. Retention of mitochondria in the bud tip of wild-type cells results in a 60% decrease in mitochondrial movement in buds compared with mother cells. In ypt11Delta mutants, however, the level of mitochondrial motility in buds was similar to that observed in mother cells. Moreover, the myo2-66 mutant, which carries a temperature-sensitive mutation in the Myo2p motor domain, exhibited a 55% decrease in accumulation of mitochondria in the bud tip, and an increase in accumulation of mitochondria at the retention site in the mother cell after shift to restrictive temperatures. Finally, destabilization of actin cables and the resulting delocalization of Myo2p from the bud tip had no significant effect on the accumulation of mitochondria in the bud tip.

Actins↗

PubMed2003

A protein complex containing Mdm10p, Mdm12p, and Mmm1p links mitochondrial membranes and DNA to the cytoskeleton-based segregation machinery.

Previous studies indicate that two proteins, Mmm1p and Mdm10p, are required to link mitochondria to the actin cytoskeleton of yeast and for actin-based control of mitochondrial movement, inheritance and morphology. Both proteins are integral mitochondrial outer membrane proteins. Mmm1p localizes to punctate structures in close proximity to mitochondrial DNA (mtDNA) nucleoids. We found that Mmm1p and Mdm10p exist in a complex with Mdm12p, another integral mitochondrial outer membrane protein required for mitochondrial morphology and inheritance. This interpretation is based on observations that 1) Mdm10p and Mdm12p showed the same localization as Mmm1p; 2) Mdm12p, like Mdm10p and Mmm1p, was required for mitochondrial motility; and 3) all three proteins coimmunoprecipitated with each other. Moreover, Mdm10p localized to mitochondria in the absence of the other subunits. In contrast, deletion of MMM1 resulted in mislocalization of Mdm12p, and deletion of MDM12 caused mislocalization of Mmm1p. Finally, we observed a reciprocal relationship between the Mdm10p/Mdm12p/Mmm1p complex and mtDNA. Deletion of any one of the subunits resulted in loss of mtDNA or defects in mtDNA nucleoid maintenance. Conversely, deletion of mtDNA affected mitochondrial motility: mitochondria in cells without mtDNA move 2-3 times faster than mitochondria in cells with mtDNA. These observations support a model in which the Mdm10p/Mdm12p/Mmm1p complex links the minimum heritable unit of mitochondria (mtDNA and mitochondrial outer and inner membranes) to the cytoskeletal system that drives transfer of that unit from mother to daughter cells.

Cytoskeleton↗

PubMed2003

Toxicity of metal ions used in dental alloys: a study in the yeast Saccharomyces cerevisiae.

Metal ions are released from dental alloys into the oral environment, which can cause biological responses over short and extended periods. Since most toxic metal ions are capable of inducing oxidative stress on cells through the mitochondrial respiratory chain, mitochondria may contribute to and be a target of metal toxicity. In this study, we investigated the effect of metal ions on growth of the budding yeast, Saccharomyces cerevisiae, and on the morphology and function of yeast mitochondria. Moreover, we tested whether mitochondrial respiratory activity contributes to metal toxicity. Metal ions affected yeast cell growth. The toxicity of metal ions to yeast cells, ranked in decreasing order are as follows: Hg > Ag > Au > Cu, Ni, Co, Zn. This result mostly correlates with the degree of toxicity of those metal ions to growth of human cells. The MIC90 of Hg, Ag and Au ions in synthetic complete media are 0.325, 5 and 320 microM, respectively. None of the toxic metal ions resulted in loss of mitochondrial respiratory activity. However, respiration-deficient rho0 cells appeared to be resistant to Ag ion, but not to Hg and Au ions. Furthermore, at high concentrations, Ag ion caused morphological changes in mitochondria. These studies indicate that yeast may be used as a model system to screen for toxic effect of metals ions from dental alloys, and that oxidation activity in mitochondria may play a role in acute toxicity of silver ion.

Cell Division↗