The aim of this study was to evaluate the effect of controlled intraoral grinding and polishing on the roughness of full-contour zirconia compared to classical veneered zirconia. Thirty bar-shaped zirconia specimens were fabricated and divided into two groups (n=15). Fifteen specimens (group 1) were glazed and 15 specimens (group 2) were veneered with feldspathic ceramic and then glazed. Prior to grinding, maximum roughness depth (Rmax) values were measured using a profilometer, 5 times per specimen. Simulated clinical grinding and polishing were performed on the specimens under water coolant for 15 s and 2 N pressure. For grinding, NTI diamonds burs with grain sizes of 20 µm, 10 µm, and 7.5 µm were used sequentially. The ground surfaces were polished using NTI kits with coarse, medium and fine polishers. After each step, Rmax values were determined. Differences between groups were examined using one-way analysis of variance (ANOVA). The roughness of group 1 was significantly lower than that of group 2. The roughness increased significantly after coarse grinding in both groups. The results after glazing were similar to those obtained after fine grinding for non-veneered zirconia. However, fine-ground veneered zirconia had significantly higher roughness than venerred, glazed zirconia. No significant difference was found between fine-polished and glazed zirconia, but after the fine polishing of veneered zirconia, the roughness was significantly higher than after glazing. It can be concluded that for full-contour zirconia, fewer defects and lower roughness values resulted after grinding and polishing compared to veneered zirconia. After polishing zirconia, lower roughness values were achieved compared to glazing; more interesting was that the grinding of glazed zirconia using the NTI three-step system could deliver smooth surfaces comparable to untreated glazed zirconia surfaces.
Aluminum Silicates ; chemistry ; Ceramics ; chemistry ; Crowns ; Dental Materials ; chemistry ; Dental Polishing ; instrumentation ; methods ; Dental Prosthesis Design ; Dental Veneers ; Diamond ; chemistry ; Humans ; Materials Testing ; Microscopy, Electron, Scanning ; Particle Size ; Potassium Compounds ; chemistry ; Pressure ; Surface Properties ; Time Factors ; Water ; chemistry ; Yttrium ; chemistry ; Zirconium ; chemistry

Thyrotoxic periodic paralysis (TPP) is a rare manifestation of hyperthyroidism characterized by muscle weakness and hypokalemia. All ethnicities can be affected, but TPP typically presents in men of Asian descent. The most common cause of TPP in thyrotoxicosis is Graves' disease. However, TPP can occur with any form of thyrotoxicosis. Up to our knowledge, very few cases ever reported the relationship between TPP and painless thyroiditis. We herein report a 25-yr-old Korean man who suffered from flaccid paralysis of the lower extremities and numbness of hands. The patient was subsequently diagnosed as having TPP associated with transient thyrotoxicosis due to painless thyroiditis. The paralytic attack did not recur after improving the thyroid function. Therefore, it is necessary that early diagnosis of TPP due to transient thyrotoxicosis is made to administer definite treatment and prevent recurrent paralysis.
Administration, Oral ; Adult ; Anti-Arrhythmia Agents/therapeutic use ; Humans ; Hypokalemic Periodic Paralysis/*diagnosis/drug therapy/etiology ; Male ; Organotechnetium Compounds/chemistry/diagnostic use ; Potassium Chloride/therapeutic use ; Propranolol/therapeutic use ; Radiopharmaceuticals/diagnostic use ; Thyroiditis/*complications/radiography/ultrasonography ; Thyrotoxicosis/*diagnosis/etiology

BACKGROUND: Methylmercury is an organic form of mercury that is highly toxic to humans. Here, we present and establish a novel method to detect methylmercury concentrations in the blood of Koreans. METHODS: Methylmercury concentration was analyzed with an automated methylmercury analytic system (MERX, Brooks Rand Co., USA) using cold vapor atomic fluorescence spectrophotometry (CVAFS). A variety of biological materials were digested in methanolic potassium hydroxide solution. The analysis method was validated by examination of certified reference material (955c, National Institute of Standard and Technology, USA). We randomly selected 30 Korean adults (age 20 yr or older) to analyze total blood mercury and methylmercury concentrations. RESULTS: The detection limit and methylmercury recovery rate using this method were 0.1 pg/L and, 99.19% (range: 89.33-104.89%), respectively. The mean blood concentration of methylmercury was 4.54+/-2.15 microg/L (N=30). The mean proportion of methylmercury to the total mercury concentration was 78.27% (range: 41.37-98.80%). CONCLUSIONS: This study is the first report to analyze blood methylmercury concentration using CVAFS in Korea. We expect that this method will contribute to the evaluation of mercury exposure and the assessment of the toxicological impact of mercury in future studies.
Adult ; Humans ; Hydroxides/chemistry ; Mercury/blood ; Methylmercury Compounds/*blood ; Potassium Compounds/chemistry ; Reproducibility of Results ; Republic of Korea ; *Spectrophotometry, Atomic

In order to investigate the effects of pyrolysis conditions on bio-oil production from biomass in molten salt, experiments of biomass pyrolysis were carried out in a self-designed reactor in which the molten salt ZnCl2-KCl (with mole ratio 7/6) was selected as heat carrier, catalyst and dispersion agent. The effects of metal salt added into ZnCl2-KCl and biomass material on biomass pyrolysis were discussed, and the main compositions of bio-oil were determined by GC-MS. Metal salt added into molten salt could affect pyrolysis production yields remarkably. Lanthanon salt could enhance bio-oil yield and decrease water content in bio-oil, when mole fraction of 5.0% LaCl3 was added, bio-oil yield could reach up to 32.0%, and water content of bio-oil could reduce to 61.5%. The bio-oil and char yields were higher when rice straw was pyrolysed, while gas yield was higher when rice husk was used. Metal salts showed great selectivity on compositions of bio-oil. LiCl and FeCl2 promoted biomass to pyrolyse into smaller molecular weight compounds. CrCl3, CaCl2 and LaCl3 could restrain second pyrolysis of bio-oil. The research provided a scientific reference for production of bio-oil from biomass pyrolysis in molten salt.
Biofuels ; analysis ; Bioreactors ; microbiology ; Catalysis ; Chlorides ; chemistry ; Lanthanum ; chemistry ; Lipids ; biosynthesis ; Oryza ; metabolism ; Plant Stems ; metabolism ; Potassium Chloride ; chemistry ; Salts ; chemistry ; Zinc Compounds ; chemistry

OBJECTIVEThe effect of the different fertilizing levels on yields and main active components of Pinellia ternata from Sichuan was studied under the cultivated condition, in order to provide theoretical basis for the standardized cultivation.

METHODUsing one of the wild populations of P. ternate from Sichuan as tested material, the experiment was performed with orthogonal designing methods L25 (5(3)). During growth and development period, agronomic traits such as number of sprouting, inflorescence and bulblets were counted. After harvesting, main chemical compositions, growth and proliferation rates were determined.

RESULTIn different fertilizing levels, the P. ternata from Sichuan showed the same growth rhythm, though there were significant difference (P < 0.05) among the average emergence rate,whereas extremely significant difference (P < 0.01) were detected among the average ratio of bolting, the average bulbils, individual growth rate, individual proliferation rate, beta-sitosterol and alkaloid content under different fertilizing levels. Nitrogenous fertilizer that affected the content of alkaloids and beta-sitosterol were extremely significant (P < 0.01), whereas phosphate and potassium fertilizer had no significant effect. The effect of fertilizer factor and inter effects on beta-sitosterol showed no significant effect, but have influence on other indexes.

CONCLUSIONThe optimum fertilizer composition was 315 kg x hm(-2) of nitrogen, 225 kg x hm(-2) of P2O5 and 270 kg x hm(-2) of K2O.

Alkaloids ; analysis ; Fertilizers ; Nitrogen Compounds ; analysis ; Phosphates ; analysis ; Phosphorus Compounds ; analysis ; Pinellia ; chemistry ; growth & development ; Potassium Compounds ; analysis ; Sitosterols ; analysis

This study is designed to investigate the effects of chinfloxacin hydrochloride (CFX) on the kinetics of HERG K+ channel. Whole cell patch clamp technique was used to record HERG K+ currents from HEK293 cells transiently transfected with cgi-HERG-GFP plasmids and channel kinetics were assessed in the absence and presence of CFX and moxifloxacin hydrochloride (MOX). Results demonstrated that the open state of HERG K+ channel was inhibited by CFX in a concentration- and time-dependent manner, with an IC50 of 162.1 +/- 14.2 micromol x L(-1), two folds higher than its positive control MOX. But there were no significant effects on channel kinetics. In addition, the inhibitory effect of CFX on HERG was enhanced when cells were subjected to altered extracellular K+ concentration.
Anti-Bacterial Agents ; administration & dosage ; chemistry ; pharmacology ; Aza Compounds ; pharmacology ; Dose-Response Relationship, Drug ; Ether-A-Go-Go Potassium Channels ; antagonists & inhibitors ; physiology ; Fluoroquinolones ; administration & dosage ; chemistry ; pharmacology ; HEK293 Cells ; Humans ; Inhibitory Concentration 50 ; Kinetics ; Molecular Structure ; Patch-Clamp Techniques ; Potassium ; pharmacology ; Quinolines ; pharmacology ; Time Factors ; Transfection

The purpose of this study is to investigate the function of a novel potassium transporter gene (NrHAK1) isolated from Nicotiana rustica roots using yeast complement and real-time PCR technique. The complementary DNA (cDNA) of NrHAK1, 2 488 bp long, contains an open reading frame (ORF) of 2 334 bp encoding a protein of 777 amino acids (87.6 kDa) with 12 predicted transmembrane domains. The NrHAK1 protein shows a high sequence similarity to those of high-affinity potassium transporters in Mesembryanthemum, Phytolacca acinosa, Arabidopsis thaliana, and so on. We found that the NrHAK1 gene could complement the yeast-mutant defect in K+ uptake. Among several tissues surveyed, the expression level of NrHAK1 was most abundant in the root tip and was up-regulated when exposed to potassium starvation. Moreover, the transcript accumulation was significantly reduced by adding 5 mmol/L NH4+ to the solution. These results suggest that NrHAK1 plays an important role in potassium absorption in N. rustica.
Cation Transport Proteins ; chemistry ; genetics ; physiology ; Plant Proteins ; chemistry ; genetics ; physiology ; Potassium ; metabolism ; Quaternary Ammonium Compounds ; pharmacology ; Sodium ; pharmacology ; Tobacco ; genetics ; metabolism

OBJECTIVETo study the effects of resvaratrol derivatives on spontaneous HR and CF of isolated guinea pig atrium.

METHODThe dose-effect curve of resvaratrol was observed. The possible mechanism of potassium channels responsible for changes of CF and HR after administering with resvaratrol was measured.

RESULTResvaratrol reduced the spontaneous HR and weakened the CF in a dose-dependent manner ranging from 10(-6) to 3 x 10(-4) mol x L(-1) (P < 0.05). As compared with Res group, the effects were partly blocked by Gli (P < 0.05) and TEA (P < 0.01), but not blocked by 4-AP, BaCl2, Atropine.

CONCLUSIONResvaratrol can induce negative chronotropic action and negative (inotropic action. The mechanism(s) may relate to the opening of K(ATP) and Kc(Ca).

Animals ; Barium Compounds ; pharmacology ; Cardiotonic Agents ; administration & dosage ; isolation & purification ; pharmacology ; Chlorides ; pharmacology ; Dose-Response Relationship, Drug ; Female ; Glyburide ; pharmacology ; Guinea Pigs ; Heart Rate ; drug effects ; In Vitro Techniques ; KATP Channels ; antagonists & inhibitors ; Male ; Myocardial Contraction ; drug effects ; Plants, Medicinal ; chemistry ; Potassium Channel Blockers ; pharmacology ; Potassium Channels, Calcium-Activated ; antagonists & inhibitors ; Potassium Channels, Inwardly Rectifying ; antagonists & inhibitors ; Stilbenes ; administration & dosage ; isolation & purification ; pharmacology ; Tetraethylammonium ; pharmacology

OBJECTIVETo explore the effects of paeoniflorin on antagonising the delayed neuronal death (DND) induced by cerebral ischemia,and the relation between DND, cerebral tissue energy metabolism, nitric oxide (NO) and nitric oxide synthase (NOS).

METHODIncomplete cerebral ischemia induced was induced by ligating bilateral arteries carotis communis for 20 min followed by reperfusion 48 h in rats. The indexes including Na(+)-K(+)-ATPase activity, lactic acid content, Ca(2+)-ATPase, Mg(2+)-ATPase activity, NO content and NOS activity were determined in fore brain cortex at 48 h after reperfusion.

RESULTNa(+)-K(+)-ATPase, Ca(2+)-ATPase and Mg(2+)-ATPase activity were lowered (P < 0.01), NO level was decreased (P < 0.01), NOS activity dropped (P < 0.01) in cerebral tissue at 48h after reperfusion, but lactic acid level had no change. Paeoniflorin could prevent reduction of Na(+)-K(+)-ATPase activity (P < 0.05, P < 0.01), increase NO level (P < 0.01), enhance NOS activity (P < 0.01) at 48h after reperfusion.

CONCLUSIONDND induced by ischemia may be concerned with energy metabolism disorder and decrease of NO formation. Paeoniflorin may play the role of antagonising cerebral ischemia by adjusting cerebral energy metabolism and nitric oxide formation.

Animals ; Benzoates ; isolation & purification ; pharmacology ; Brain ; metabolism ; Brain Ischemia ; complications ; Bridged-Ring Compounds ; isolation & purification ; pharmacology ; Ca(2+) Mg(2+)-ATPase ; metabolism ; Calcium-Transporting ATPases ; metabolism ; Energy Metabolism ; Female ; Gerbillinae ; Glucosides ; isolation & purification ; pharmacology ; Lactic Acid ; metabolism ; Male ; Monoterpenes ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; metabolism ; Paeonia ; chemistry ; Plants, Medicinal ; chemistry ; Reperfusion Injury ; etiology ; metabolism ; Sodium-Potassium-Exchanging ATPase ; metabolism

AIMTo develop a new method for the determination of clarithromycin.

METHODSThe catalytic wave of clarithromycin in the presence of K2S2O8 was used for improving the analytical sensitivity. The rapid determination of clarithromycin has been carried out by linear single sweep polarography.

RESULTSThe reduction wave of clarithromycin appeared at ca. -0.79 V (vs SCE) in 0.24 mol x L(-1) KH2PO4-Na2HPO4 (pH 6.81) supporting electrolyte, which was ascribed to the reduction of carbonyl group on C-9 position. In the presence of 0.01 mol x L(-1) K2S2O8, the reduction wave was catalyzed to produce a parallel catalytic wave. The peak current of the catalytic wave was ca. Twenty times higher than that of the corresponding reduction wave. Based on the catalytic wave, a new method for the determination of clarithromycin has been proposed. The peak current of the catalytic wave was rectilinear to clarithromycin concentration in the range of 4.0 x 10(-7)-5.0 x 10(-5) mol x L(-1). The detection limit was 2.0 x 10(-7) mol x L(-1).

CONCLUSIONThe proposed method could be used for the direct determination of clarithromycin in pharmaceuticals and urine without preliminary separation.

Anti-Bacterial Agents ; analysis ; chemistry ; Catalysis ; Clarithromycin ; analysis ; chemistry ; Hydrogen-Ion Concentration ; Polarography ; methods ; Potassium Compounds ; chemistry ; Sulfates ; chemistry