• Molecules and Cells
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• v.19 no.2
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• pp.232-238
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• 2005

Corneal endothelial cells play an important role in maintaining the transparency and ionic balance of the cornea. Inflammation causes many changes in the intracellular and extracellular environment of the cornea, including acidosis. We examined the relationship between changes in extracellular pH and expression of cyclooxygenase-2 in cultured bovine corneal endothelial cells. When extracellular pH ($[pH]_o$) was reduced to pH 6.4, COX-2 mRNA increased, with a peak at 2 h. This was blocked by pretreatment with actinomycin D and incubation with spermine NONOate (SPER/NO, a nitric oxide donor). Exposure to the $H^+$ ionophore, carbonyl cyanide m-chlorophenylhydrazone (CCCP), also raised COX-2 mRNA levels. CCCP-induced COX-2 mRNA expression was also reduced by SPER/NO. These results were confirmed immuno-cytochemically. These data demonstrate that COX-2 expression is stimulated by the lowering of extracellular pH that could result from bacterial infection, and that this is countered by over-production of nitric oxide, which could also result from bacterial infection.

• Applied Biological Chemistry
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• v.30 no.2
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• pp.169-178
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• 1987

The extracellular and intracellular inulases from Kluyveromyces marxianus were purified and characterized. The maximum production of both inulases was achieved at stationary phase in a pH-controlled medium at pH 5 with yeast nitrogen base as organic nitrogen source. Each enzyme was concentrated by tannic acid precipitation and separated into two fractions by DEAF-cellulose chromatography. Electrophoretic analysis showed that the four fractions had three glycoprotein bards each. Only main glycoprotein band, however, had both inulase and invertase activities. There were no significant differences between two enzymes in the optimum pH and temperature. But the intracellular inulases had higher heat stability and less affinity toward inulin than the extracellular enzymes do. All the purified enzymes were considered to be exo-inulases using hydrolyzate analysis with TLC.

• The Korean Journal of Physiology and Pharmacology
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• v.6 no.5
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• pp.255-260
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• 2002

The effects of intracellular and extracellular pH on the inwardly rectifying $K^+$ (IRK) channel of the bovine aortic endothelial cells (BAECs) were examined using whole-cell patch-clamp technique. The IRK current, efficiently blocked by $Ba^{2+}\;(200{\mu}M),$ is the most prominent membrane current in BAECs, which mainly determines the resting membrane potential. The expression of Kir2.1 was observed in BAECs using reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. Intracellular alkalinization, elicited by the extracellular substitution of NaCl with $NH_4Cl$ (30 mM), significantly augmented the amplitude of IRK current. On the contrary, the amplitude of IRK current was attenuated by the Na-acetate (30 mM)-induced intracellular acidification. The changes in extracellular pH also closely modulated the amplitude of IRK current, which was decreased to $40.2{\pm}1.3%$ of control upon switching the extracellular pH to 4.0 from 7.4. The extracellular pH value for half-maximal inhibition (pK) of IRK current was 5.11. These results demonstrate that the activity of IRK channel in BAECs, probably Kir2.1, was suppressed by proton at both sides of plasma membrane.

• Journal of Chest Surgery
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• v.12 no.4
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• pp.395-402
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• 1979

Intracellular pH was determined by distribution of 5.5-dimethyl-2,4-oxazolidlnedione [DMO]in the skeletal muscle of dogs before and after lactic acidosis induced by intravenous infusion of lactic acid solution. After infusion of lactic acid solution arterial pH decreased from 7.40 to around 7.12 [P<0.001]and metabolic acidosis was induced. However, dose-pH change response was not proportional as in the case of hydrochloric acid infusion. During lactic acidosis, intracellular pH changed very little except when venous blood $pCO_2$ increased significantly. The decrease of intracellular pH in lactic acidosis might be due primarily to the increase of intracellular $pCO_2$. And during lactic acidosis, change of extracellular pH was larger than that of intracellular pH, and this was also the case of change In hydrogen Ion concentration in extracellular and intracellular fluid. The fact was estimated that exogenous lactic acid transported into the cell does not contribute to pH change by the participation in the metabolism. Change in plasma potassium Ion concentration was not eminent as metabolic acid-base disturbances by other origin, and changing pattern of Hi/He ratio was not same as Ki/Ke ratio. In spite of no changes in extracellular potassium ion concentration after exogenous lactic acidosis total amount of potassium ion in extracellular fluid increased from 12.62mEg to 18.26mEg [P< 0.05].

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.321-324
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• 2000

The Effect of pH red pigment production by Monascus purpureus ATCC 16365 has been studied in pH-controlled batch fermenter culture. A maximum of yellow and red pigments were detected using UV-Vis spectrophotometer at 385nm and 495nm, respectively. Fungal growth and pigment production were favoured at low pH(pH 4.0-5.5). Especially extracellular formation rate of orange to yellow pigment was decreased compared with that of orange to red pigment at pH 7.0. In addition, the enhancement of ratio of extracellular to intracellular pigment and the red pigment production in pH 7.0-controlled batch fermenter was observed. However, the pH 7.0-controlled batch cultures depressed the total production of pigments. The pH change from 4.0 to 7.0 during batch fermenter cultivations sharply increased both red pigment production and the extracellular composition.

• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.849-854
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• 2006

The effects of Haematococcus pluvialis extracellular products on microbial growth and bacteriocin production were investigated to improve bacteriocin synthesis during the growth cycle of Lactobacilli. Lactobacillus pentosus KJ-108, L. plantarum KJ-10311, and L. sakei KJ-2008 were cultured in MRS and enriched medium (ERM) with or without supplement of the extracellular products obtained from a late exponential phase culture of Haematococcus pluvialis in modified Bold's basal medium (MBBM). In both MRS and ERM, the extracellular products strongly enhanced the growth as well as the bacteriocin production of all the lactic acid bacteria tested. The enhancing effect was observed in ERM with pH adjusted at 5 and 6. In addition, some difference in growth effects with the extracellular products of H. pluvialis was observed between pH 5 and 6 in ERM, but no effect was observed in the minimal medium. The final biomass and the final concentration of bacteriocin activity were associated with the cell growth that was promoted by the extracellular products of H. pluvialis, and the enhanced cell growth of the three lactic acid bacterial strains induced the increase of the specific bacteriocin production. Therefore, bacteriocin production and activity were influenced by the addition of the extracellular products of H. pluvialis in the culture medium.

• Applied Biological Chemistry
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• v.39 no.6
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• pp.449-454
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• 1996

We investigated the optimal condition for the production of extracellular pretense(a cuticle-degrading pretense) from entomopathogenic fungus Beauveria bassiana(ATCC7159) in liquid medium by adding of gelatin, bovine serum albumin(BSA), casein and polypeptone. The optimal induction medium for production of extracellular pretenses is composed of 0.5% polypeptone, trace elements and 50 mM potassium phosphate(pH 6.0). In this condition, the production of extracellular pretenses increased rapidly after the 24hrs, peaking at the third day and there was little inductive effect in culture broth more than pH 7.0. The pretenses were inhibited by phenyl methyl sulfonyl fluoride(PMSF). High activity of pretense was showed both range of pH 8.5 and 11.5 and also detected by three different portions of slice gel derived from non-denaturing isoelectricfocusing gel. At least three different extracellular pretenses are produced in optimal production medium when polypeptone is used as the sole carbon and nitrogen source.

• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.306-311
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• 1987

After series of purification by means of ammonium sulfate fractionation, the 1st and 2nd DEAE-Cellulose, DEAE-Sephadex A-50, and Sephacryl S-200 superfine gel filtration, the activity of extracellular adenine deaminase from Streptomyces sp. J-350P increased 1764 fold and the yield was 0.3% of original activity. The enzyme was stable at the pH range 6.5 to 8.5 and at up to 5$0^{\circ}C$. The optimum pH and temperature of the enzyme were around 6.5 and 35$^{\circ}C$. The molecular weight ol the enzyme was estimated as 36, 000 by calibrated Sephacryl S-200 superfine column chromatography.

• Journal of Life Science
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• v.20 no.6
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• pp.902-906
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• 2010

A producer of thermophilic extracellular lipase, Geobacillus kaustophilus DSM 7263, was selected from various microorganisms of the Geobacillus genus. We investigated optimum conditions for mass production of G. kaustophilus lipase. Among the different natural oil media, olive oil was optimal for enzyme production. The maximum amount of enzyme production was obtained when G. kaustophilus was grown in a medium containing 0.5% olive oil as a carbon source. The pH and temperature for optimal growth were pH 8.0 and $55^{\circ}C$, respectively, while the optimum pH and temperature for lipase production were pH 6.0 and $50^{\circ}C$, respectively. In the presence of $Mg^{2+}$ and $Mn^{2+}$, lipase production was dramatically enhanced by 247% and 157%, respectively, whereas enzyme production was inhibited by $Zn^{2+}$, $Cu^{2+}$, and $Cd^{2+}$. The addition of 0.1% (v/v) triton X-100 increased lipase production and cell growth when compared to the negative control.

• The Korean Journal of Physiology
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• v.24 no.1
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• pp.161-170
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• 1990

The effects of $H^{+}$ on the arterial contraction and their mechanisms were investigated in the renal artery of a rabbit. The helical strips of isolated renal artery were immersed in the HEPES-buffered or $CO_{2}/HCO_{3}^{-}$-buffered Tyrode's solution. The contractions induced by agonists (norepinephrine, histamine, serotonin and angiotensin II) or high $K^{+}$ were observed with change of extracellular or intracellular $H^{+}$ concentration. The contractions induced by norepinephrine, histamine, serotonin, angiotensin II or high $K^{+}$ in HEPES-buffered Tyrode's solution were inhibited by increase in extracellular $H^{+}$ concentration and potentiated by decrease in extracellular $H^{+}$ concentration. The degrees of these effects were most evident in the contraction induced by serotonin and angiotensin II, moderate in those by histamine and high $K^{+}$, and least in those by norepinephrine. Maximal contraction by norepinephrine, histamine and high $K^{+}$ were not influenced by change in extracellular $H^{+}$ concentration, but influenced in those contration by serotonin and angiotensin II. The attenuated contractions by an acidic pH were not returned to the level of contraction at normal pH (7.4) by elevation of extracellular $Ca{2+}$ concentration. The agonists (norepinephrine, histamine and serotonin)-induced contractions in $Ca{2+}$-free Tyrode's solution were also attenuated by increase in extracellular $H^{+}$ concentration and potentiated by decrease in extracellular $H^{+}$ concentration. Elevation of $Pco_{2}$ in the $CO_{2}/HCO_{3}^{-}$-buffered Tyrode's solution, which increase the intracellular $H^{+}$ concentration, at constant extracellular pH (7.4), increased the contraction by 30 mM $K^{+}$. From the above results, it is suggested that the decrease in contractions by increase in extracellular $H^{+}$ concentration may be resulted from that $H^{+}$ make the receptors less sensitive to agonists and cell membrane hyperpolarize and then inhibit the $Ca{2+}$ influx as well as $Ca{2+}$ release from intracellular $Ca{2+}$ storage site.