• Restorative Dentistry and Endodontics
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• v.18 no.2
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• pp.277-290
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• 1993

Dental caries is considered to be caused by demineralization by organic acid produced by microorganism. But the formation of subsurface lesion in initial caries make it diffcult to explain by simple demineralization. This study is carried out on the basis of thermodynamic concept proposed by Margolis and Moreno. The purpose of this study is to evaluate the effects of acid concentration and pH of lactate buffer system on the artificial caries lesion progress. 160 teeth without any crack, defect or opaque enamel were used and coated with nail varnish except the window ($2{\times}3$ mm). Under the constant degree of saturation(D.S.). The teeth were divided into 8 groups according to acid concentration(10mM, 25mM, 50mM, 100mM) and pH(4.3, 5.0, 6.0). Each group was immersed in buffer solution for 3, 6, 9, 18 days under controlled temperature($25^{\circ}C$). After cutting through the window and grinding, the specimens, 100-150 um in thickness, were imbibed in water or air and examined using polarilizing microscope. The depth of the surface and subsurface surface lesion were measured. 1. In the constant pH and D. S. value, the subsurface lesion progresses more rapidly as the concentration of lactic acid increases. (0.01, 0.025, 0.05, 0.1) 2. In the constant acid concentration and DS value, the subsurface lesion progresses more slowly as the pH increases. (4.3, 5.0, 5.5, 6.0) 3. The width of surface lesion seems to be constant independant of pH and acid concentration.

• The korean journal of orthodontics
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• v.2 no.1
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• pp.23-28
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• 1971

In this study, sections of twenty eight teeth were used to investigate the effect of topical application of $8\%$ stannous fluoride on the decalcification rate of enamel surfaces stripped in a manner suggested for orthodontic purpose. The enamel treated with a single application of a fluoride had a significantly lower tile rate of decalcification for the first 96 hours to lactate buffer solution. After double application of fluoride, decalcification rate decreased signicantly. This study suggested that the continuing protection of stripped surfaces should be sought by regularly scheduled treatment of the enamel with the topical application of fluoride and regular use of a fluoride containing dentifrice.

• Analytical Science and Technology
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• v.19 no.6
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• pp.482-489
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• 2006

Two electrode-based lactate biosensor was prepared by immobilizing lactate oxidase (LOD) obtained from pediococcus species in a poly(vinyl alcohol). Hydrogen peroxide ($H_2O_2$) produced by the reaction of lactate and LOD was detected on the Pt-black that was electrochemically deposited on the Au electrode. Sensors fabricated with Pt-black deposited Au electrode provided a high current of $H_2O_2$ oxidation at a substantially lowered applied potential (+300 mV vs. Ag/AgCl), resulting in reduced interferences from easily oxidizable species such as ascorbic acid, acetaminophen, and uric acid. An outer membrane is formulated by adjusting water uptake of hydrophilic polyurethane (HPU). The sensor performance was evaluated in vitro with both flow-through arrangement and static mode. The sensor showed a linear range from 0.1 mM to about 9.0 mM in 0.05 M phosphate buffer (pH 7.6) containing 0.05 M NaCl. Storing the sensors prepared in this work at $4^{\circ}C$ buffer solution while not in use, they provided same electrochemical performance for more than 25 days.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.692-695
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• 2003

In this work immobilization technique of enzymes onto the magnetic nanoparticles has been developed for biochip applications. Glucose oxidase and lactate dehydrogenase were immobilized on magnetic nanoparticles via cyanamide and glutaraldehyde. Immobilized enzymes had good operational and storage stability The immobilized glucose oxidase and lactate dehydrogenase were characterized by some factors(pH, temperature, and components of buffer solution etc) which affect the activity, In order to characterize the magnetic nanoparticles, we have used transmission electron microscopy(TEM), X-ray diffraction(XRD) and Fourier transform infrared(FTIR).

• BMB Reports
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• v.39 no.4
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• pp.426-431
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• 2006

Embryonic stem cells (ESCs), representing a population of undifferentiated pluripotent cells with both self-renewal and multilineage differentiation characteristics, are capable of spontaneous differentiation into cardiomyocytes. The present study sought to define the kinetic characterization of lactate dehydrogenase (LDH) and creatine kinase (CK) of ESC- and neonatal-derived cardiomyocytes. Spontaneously differentiated cardiomyocytes from embryoid bodies (EBs) derived from mouse ESC line (Royan B1) and neonatal cardiomyocytes were dispersed in a buffer solution. Enzymes were extracted by sonication and centrifugation for kinetic evaluation of LDH and CK with spectrophotometric methods. While a comparison between the kinetic properties of the LDH and CK of both groups revealed not only different Michaelis constants and optimum temperatures for LDH but also different Michaelis constants and optimum pH for CK, the pH profile of LDH and optimum temperature of CK were similar. In defining some kinetic properties of cardiac metabolic enzymes of ESC-derived cardiomyocytes, our results are expected to further facilitate the use of ESCs as an experimental model.

• Journal of Preventive Medicine and Public Health
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• v.33 no.1
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• pp.117-124
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• 2000

Objectives : It is the objective of this study to compare hepatotoxicity of nickel chloride and cadmium chloride with each other through IPRL(Isolated Perfused Rat Liver) method. Methods : Biochemical indicator of hepatic function such as AST(aspartate aminotransferase), ALT(alanine aminotransferase), LDH(lactate dehydrogenase) and perfusion flow rate were used as the indicator of hepatotoxicity. Oxygen consumption rate were used as vability indicator. $300({\pm}50)g$ - weighted rats were allocated randomly to each group($0{\mu}M,\;50{\mu}M,\;200{\mu}M\;NiCl_2\;and\;CdCl_2$ exposure) by 5, totally 25. After Krebs-Ringer bicarbonate butler solution flowed into the penal vein and passed the liver cell, it flowed out of vena cava. Liver was administered with each $NiCl_2\;and\;CdCl_2$ of each concentration and observed with buffer solution sampling time. Butler which got out of liver was sampled and then biochemical indicator of hepatotoxicity was measured. Results : AST, ALT, and LDH in buffer increased with sampling time much more in $CdCl_2$ exposure group than $NiCl_2$ exposure group in both 50 and $200{\mu}M$ and statistical significance w3s verified with 2-way repeated ANOVA. Viability was decreased more and more in all substances during passed time. Conclusions : It is inferred that $CdCl_2$ has stronger hepatotoxicity than $NiCl_2$. IPRL method would be used widely for acute hepatotoxicity when considerating the benefit of it.

• Polymer(Korea)
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• v.31 no.3
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• pp.233-238
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• 2007

The purpose of the study is to apply composites of poly (glycolic acid) (PGA) with [poly(R) 3-hydroxybutyrate] (P3HB) or poly (butylenes succinate- co-L-lactate) (PBSL) as medical resorbable composite materials with the complement of hydrolysis rate of each component. As a result, it was confirmed that the PBSL/PGA and P3HB/PGA composite fiber were hydrolyzed in phosphate buffer solution. Also, it has been revealed that the degradation of PBSL/PGA are accelerated due to PGA producing glycolic acid which can act as a catalyst. In addition, the hydrolysis of PBSL/PGA was found to be accelerated by the presence of lipase PS. When the PBSL/PGA composite fiber was placed in the air, not much hydrolysis has proceeded. Also, it was confirmed that the P3HB/PGA composite fiber maintained proper tensile strength in the air. Therefore, these complex fibers can be adapted to use as environmentally suitable, medically absorbable composite materials.

• Journal of Oral Medicine and Pain
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• v.18 no.1
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• pp.45-53
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• 1993

It is known that human saliva includes various kinds of salivaru proteins that show genetic polymorphism. Withrespect to salivary protein polymorphism, this study was conducted on 160 healthy Koreans between the ages of 20 and 29 chosen randomly : their parotid slaiva was collected, freeze-dried, and horizontally electrophoresed over acid-urea starch gel. Aluminum lactate-lactic acid was also used as buffer solution. The gel was stained with amidoblack 10B/1% acetic acid solution, and then destained with 0.5M H2SO4 solution. Accordingly, the parotid middle-band protein(Pm) identified, and its phenotypes and gene frequency were obtained. The obtined results were as follows : 1. The phenotypes of parotid middle band protein(Pm) observed in parotid saliva of the 160 Koreans were Pm(+) in 91 people (56.9%) and Pm(-) in 69 people (43.1%) 2. The gene frequency of Pm+ was 0.343, and that of Pm-waw 0.657. 3. The gene frequency of parotid middle band protein (Pm) obtained from Korean's parotid saliva was midway between that of Japanese and Chinese.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2466-2470
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• 2007

A new highly salicylate-selective PVC membrane electrode based on tripodal tris-thiourea derivatives, L1 and L2, as neutral carriers is described. The electrodes display an excellent potentiometric response to salicylate ions and an anti-Hofmeister selectivity sequence in the following order: Salicylate? > ClO4 ? > Benzoate? > I? >NO3? > NO2? > Maleate? > Acetate? > Lactate? > Fumarate?. It also exhibited a near-Nernstian potential in a linear range of 5.0 × 10?5 - 1.0 × 10?1 M with a detection limit of 9.0 × 10?5 mol/L and a slope of ?59.9 mV/decade at a pH of 7.0 in a saline buffer solution at 25 oC. The stability constant (log KS) of the anionsionophore complex was also determined at 25 oC by a conductometric titration in DMSO solution.

• Journal of Korean society of Dental Hygiene
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• v.12 no.2
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• pp.335-343
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• 2012

Objectives : The aim of this investigation was to evaluate the remineralization effect of Bamboo salt and NaF+Bamboo salt solutions on bovine enamel formed incipient artificial enamel caries by microcomputed tomography (micro CT). Methods : Experimental solutions were distilled water(negative control), 2% sodium fluoride solution (2% NaF group), 3% bamboo salt solution (3% BS group) and the solution mixed 2% sodium fluoride solution and 3% bamboo salt solution (2% NaF+3% BS group). Specimens were prepared from extracted bovine teeth and divided into 4 groups of 10 specimens each by randomized blocks according to density. Then the specimens surface were divided equally into three parts to observe sound enamel area, incipient enamel carious area and remineralized enamel area. Only one-third of specimen surface was coated with nail varnish and these were exposed to a lactate carbopol buffer system for 72 hours. Then one-half of the demineralized enamel area was coated with nail varnish. The specimens were carried out under pH cycling model for 14 days as follows; samples were immersed in each experimental solution for 2 mins 3 times per day, demineralized for 4 hours and in mixed saliva for the remaining hours. After pH cycling, density was measured using micro CT. Results : All experimental groups showed remineralization effects except for negative control group(p<0.05). The differences of density after experimental solution treatment were statistically significant difference among 4 groups (p<0.01). The density difference values of groups were $0.04{\pm}0.01$ in negative control group, $0.19{\pm}0.01$ in 2% NaF group, $0.14{\pm}0.01$ in 3% BS group, and $0.21{\pm}0.01$ in 2% NaF+3% BS group. Conclusions : The bamboo salt solution showed remineralization effects on incipient artificial enamel caries and the solution mixed sodium fluoride solution and bamboo salt solution showed more remineralization effects than the bamboo salt solution. Thus, it is suggested that bamboo salt can be used as remineralization agent in incipient enamel caries lesion.