• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.561-574
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• 2000

Poly-P has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of poly-P on the growth of Porphyromonas endodontalis, a gram negative obligate anaerobic rod, endodontopathic bacterium. P. endodontalis ATCC 35406 was in BHI broth containing hemin and vitamin K with or without poly-P. Inhibitory effect of each poly-P which was added at the beginning(lag phase) or during(exponential phase) the culture, MIC(minimum inhibitory concentration) was determined by measuring the optical density of the bacterial cell at 540nm. Viable cell counts were measured to determined whether poly-P has a bactericidal effect. Leakage of intracellular nucleotides from P. endodontalis was determined at 260nm and morphological change of P. endodontalis was observed under the TEM(transmission electron microscope). Binding of 32P-labeled poly-P to P. endodontalis was examined. SDS-polyacrylamide gel electrophoresis and zymography were performed to observe the changes in protein and enzyme profiles of P. endodontalis, respectively. The results from this study were as follows : 1. The minimal inhibitory concentration(MIC) of poly-P to P. endodontalis appeared to be 0.04~0.05%. 2. Poly-P added to the P. endodontalis culture during the exponential phase of P. endodontalis was as much effective as poly-P added at the begining of the culture, suggesting that the antibacterial effect of poly-P is not much dependent on the initial inoculum size of P. endodontalis. 3. Poly-P are bactericidal to P. endodontalis, demonstrating the decrease of the viable cell counts. 4. Intracellular nucleotide release from the P. endodontalis, was not increased in the presence of poly-P and was not reversed by the addition of divalent cations like $Ca^{2+}$ and $Mg^{2-}$. 5. Under the TEM, it was observed that fine electro-dense materials were prominent in the poly-P grown P. endodontalis, appearing locally in the cell, and the materials were more abundant and more dispersed in the cell as the incubation time with poly-P increased. In addition, highly electron dense granules accumulated in many poly-P grown cells, most of which were atypical in their shape. 6. Binding of 32P-labeled poly-P to P. endodontalis appeared to be 32.8 and 45.5 and 53.4% at 30 minutes, 1 hours and 2 hours, respectively. 7. In the presence of poly-P. the synthesis of proteins with apparent molecular masses of 25, 27, 35, 45 was lost or drastically decreased whereas expression of a protein with an apparent molecular mass of 75 was elevated. 8. Proteolytic activity of P. endodontalis was decreased by poly-P. The overall results suggest that use of poly-P may affect the growth of P. endodontalis, and the anti-bacterial activity of poly-P seems largely bactericidal. Changes in shape, protein expression, and proteolytic activity of P. endodontalis by poly-P may be directly and indirectly attributed to the antibacterial effect of poly-P. Further studies will be needed to confirm the effect of poly-P.

• The Korean Journal of Physiology
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• v.18 no.1
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• pp.19-35
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• 1984

Since the first report of Drury and $Szent-Gy{\ddot{o}}rgyi$ in 1929, the inhibitory influences of adenosine on the heart have repeatedly been described by many investigators. These studies have shown that adenosine and adenine nucleotides have overall depressant effects, similar to those of acetylcholine. Heart beats become slow and weak. It is also well known that adenosine is a potent endogenous coronary vasodilator. Many investigations on the working mechanisms of adenosine have been focused mainly on the effects of the coronary blood flow. However, the cellular mechanisms underlying the inhibitory action of adenosine on sinus node are not well understood yet. Thus, this study was undertaken to examine the behavior of rabbit SA node under influence of adenosine. In these series of experiments three kinds of preparations were used: whole atrial pair, left atrial strip, and isolated SA node preparations. The electrical activity of SA node was recorded with conventional glass microelectrodes 30 to 50 $M{\Omega}$. The preparations were superfused with bicarbonate-buffered Tyrode solution of pH 7.35 and aerated with a gas mixture of $3%\;CO_2-97%\;O_2$ at $35^{\circ}C$. In whole atrial pair, adenosine suppressed sinoatrial rhythm in a dose-dependent manner. Effect of adenosine on atrial rate appeared at the concentration of $10^{-5}M$ and was enhanced in parallel with the increase in adenosine concentration. Inhibitory action of adenosine on pacemaker activity was more prominent in the preparation pretreated with norepinephrine, which can steepen the slope of pacemaker potential by increasing permeability of $Ca^{+2}$. Calcium ions in perfusate slowly produced a marked change in sinoatrial rhythm. Elevation of the calcium concentration from 0.3 to 8 mM increased the atrial rate from 132 to 174 beats/min, but over 10 mM $Ca^{+2}$ decreased. The inhibitory effect of adenosine on sinoatrial rhythm developed very rapidly. Atrial rate was recovered promptly from the adenosine-induced suppression by the addition of norepinephrine, but extra $Ca^{+2}$ was less suitable to restore the suppression of atrial rate. Adenosine suppressed also atrial contractility in the same dosage range that restricted pacemaker activity, even in the reserpinized preparation. In isolated SA node preparation, spontaneous firing rate of SA node at $35^{\circ}C$(mean{\pm}SEM, n=16) was $154{\pm}3.3\;beats/min. The parameters of action potentials were: maximum diastolic potential(MDP), $-73{\pm}1.7\;mV: overshoot(OS), $9{\pm}1.4\;mV: slope of pacemaker potential(SPP), $94{\pm}3.0\;mV/sec. Adenosine suppressed the firing rate of SA node in a dose-dependent manner. This inhibitory effect appeared at the concentration of $10^{-6}M$ and was in parallel with the increase in adenosine concentration. Changes in action potential by adenosine were dose-dependent increase of MDP and decrease of SPP until $10^{-4}M$. Above this concentration, however, the amplitude of action potential decreased markedly due to the simultaneous decrease of both MDP and OS. All these effects of adenosine were not affected by pretreatment of atropine and propranolol. Lowering extra $Ca^{2+}$ irom 2 mM to 0.3 mM resulted in a marked decrease of OS and SPP, but almost no change of MDP. However, increase of perfusate $Ca^{2+}$ from 2 mM to 6 or 8 mM produced a prominent decrease of MDP and a slight increase of OS and SPP. Dipyridamole(DPM), which is known to block the adenosine transport across the cell membrane, definately potentiated the action of adenosine. The results of this experiment suggest that adenosine suppressed pacemaker activity and atrial contractility simultaneously and directly, by decreasing $Ca^{2+}-permeability$ of nodal and atrial cell membranes.

• Research in Plant Disease
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• v.7 no.3
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• pp.155-163
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• 2001

Two attenuated Cucumber mosaic virus (CMV) isolates, Paf-CMV and Rs2-CMV that had been selected from CMV isolates associated with satellite RNA (satRNA) were tested for cross-protection effect in pepper plants. The viruses selected as attenuated strains appeared to be identical serologically and physically to the challenge virus (Mf-CMV), but they were lower in the dilution end-point of infectivity of crude sap than Mf-CMV When symptoms were observed in several indicator plants after inoculation, Paf-CMV and Rs2-CMV were symptomless or showed mild mosaic symptoms while another satRNA isolate Ap-CMV developed severe mosaic symptoms on the leaves as Mf-CMV. The nucleotide sequences of the satRNAs were determined by sequencing full-length cDNA clones. Paf-, Rs2- and Ap-satRNAs were 386, 335, and 347 nucleotides long, respectively, The sequences were then compared with the other known Y-satRNA, revealing that nucleotide sequences of the satRNAs consisted of 5'- and 3'-terminal conserved regions. However variations occurred on the middle regions of the sequences, especially those related to symptom interference, showing significant differences between Paf-satRNA and other isolates. Infectious transcripts of Paf-satRNA and Rs2-satRNA induced mild mosaic symptoms in pepper plants when supported by genomic RNAs of Mf-CMV. Under greenhouse conditions, Paf-CMV and Rs2-CMV were tested for cross-protection effect in pepper and tobacco (Nicotiana tabacum cv, Xanthi nc) plants against Mf-CMV. No symptoms were developed on the plants vaccinated with Paf-CMV until 3 weeks after inoculation with the virulent strain; however another attenuated isolate, Rs2-CMV, showed less effectiveness in cross-protection. Depending on the concentration of the challenged virus, symptoms sometimes appeared later in the upper leaves. However, in plants challenged with low concentrations (below 0.2 mg/ml) of the challenge inoculum, symptoms caused by the virulent strain did not develop on the plants vaccinated with Paf-CMV. In the field experiments, the number of pepper plants with severe mosaic symptoms in the control plots was progressively increased after transplanting and reached approximately 50% after 50 days. On the other hand, the incidence of mosaic disease appeared very low on the plants that had received the protective inoculation with Paf-CMV.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.9 no.2
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• pp.79-110
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• 1976

In Korea fermented fish and shellfish have traditionally been favored and consumed as seasonings or further processed for fish sauce. Three major items in production quantity among more than thirty kinds which are presently available in the market are fermented anchovy, oyster and small shrimp. They are usually used as a seasoning mixture of Kimchi in order to provide a distinctive flavor. Fermented small shrimp, Acetes chinensis is most widely and largely used ana occupies an important position in food industry of this country. But no study on its taste compounds has been reported. This study was attempted to establish the basic data for evaluating taste compounds of fermented small shrimp. The changes of such compounds during fermentation as free amino acids, nucleotides and their related compounds, TMAO, TMA, and betaine were analysed. In addition, change in microflora during the fermentation under the halophilic circumstance was also investigated. The samples were prepared with three different salt contents of 20, 30 and $40\%$ to obtain the proper degree of fermentation at a controlled tempeature of $20{\pm}2^{\circ}C$. The results are summarized as follows: Volatile basic nitrogen increased rapidly until 108 days of fermentation and afterwards it tended to increase slowly. Amino nitrogen also increased rapidly until 43 days of fermentation and then increased slowly. Extract nitrogen increased and marked the maximum value at 72 day fermentation and then decreased slowly. ADP, AMP and IMP tended to degrade rapidly while hypoxanthine increased remarkably at 27 day fermentation but slightly decreased at 72 day fermentation. It is presumed that the characteristic flavor of fermented small shrimp might be attributed to the relatively higher content of hypoxanthine. In the free amino acid composition of fresh small shrimp abundant amino acids were proline, arginine, alanine, glycine, lysine, glutamic acid, leucine, valine and threonine in order. Such amino acids like serine, methionine, isoleucine, phenylalanine, aspartic acid, tyrosine and histidine were poor. In small shrimp extract, proline, arginine, alanine, glycine, lysine and glutamic acid were dominant holding $18.5\%,\;14.6\%,\;10.8\%,\;8.7\%,\;8.1\%\;and\;7.7\%$ of total free amino acids respectively. The total free amino acid nitrogen in fresh small shrimp was $63.9\%$ of its extract nitrogen. The change of free amino acid composition in the extract of small shrimp during fermentation was not observed. Lysine, alanine glutamic acid, proline, glycine and leucine were abundant in both fresh sample and fermented products. The increase of total free amino acids during 72 day fermentation reached approximately more than 2 times as compared with that of fresh sample and then decreased slowly. Fermented small shrimp with $40\%$ of salt was too salty to be commercial quality as the results of organoleptic test showed. It is found that 72 day fermentation with $20\%\;and\;30\%$ of salt gave the most favorable flavor. It is convinced that the characteristic flavor of fermented small shrimp was also attributed to such amino acids as lysine, proline, alanine, glycine and serine known as sweet compounds, as glutamic acid with meaty taste, and as leucine known as bitter taste. The amount of betaine increased during fermentation and reached the maximum at 72 day fermentation and then decreased slowly TMA increased while TMAO decreased during fermentation. The amount of TMAO nitrogen in fermented small shrimp was $200mg\%$ on moisture and salt free base. Betaine and TMAO known as sweet compounds were abundant in fermented small shrimp. It is supposed that these compounds could also play a role as important taste compounds of fermented small shrimp. At the initial stage of fermentation, Achromobacter, Pseudomonas, Micrococcus denitrificans which belong to marine bacteria were isolated. After 40 day fermentation, they disappeared rapidly while Halabacterium, Pediococcus, Sarcian, Micrococcus morrhuae and the yeasts such as Saccharomyces sp. and Torulopsis sp. dominated. It is concluded that the most important taste compounds of fermented small shrimp were amino acids such as lysine, proline, alanine, glycine, serine, glutamic acid, and leucine, betaine, TMAO and hypoxanthine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.3
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• pp.275-284
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• 1984

In order to study the flavor quality of Chungkookjang, the changes in nitrogenous compounds, nucleotides and their related compounds, free amino acids, amino acid composition and fatty acids were analysed during Chungkookjang Koji fermentation. Koji was prepared with Bacillus natto isolated from Japanese natto. Insoluble nitrogenous was rapidly decreased, whereas PAA (peptide, amino, ammonia) nitrogen were slightly increased during the fermentation of Chungkookjang Koji. The content of extracted nitrogen and free amino acid nitrogen were rapidly increased until 48 hours fermentation of Chungkookjang Koji and then decreased. The contents of ADP, ATP, AMP and inosine in raw soybean were abundant. The contents of ADP, ATP and AMP were decreased while inosine and hypoxanthine were increased during the fermentation of Chungkookjang Koji. The free amino acids analyzed in this experiment were not changed in composition but changed in amounts during the fermentation of Chungkookjang Koji. The contents of alanine, valine, isoleucine and phenylalanine were continually increased during the fermentation of Chungkookjang Koji. The contents of lysine, histidine, arginine, glutamic acid, glycine, methionine and tyrosine were increased until 48 hours fermentation and then decreased gradually. The increase in the contents of aspartic acid, threonine, serine, proline and cystine were fluctuated. In raw soybean, amino acid composition such as glutamic acid, serine and proline were dominant amino acid and amounts those were 63.8% of the total amino acids. The contents of aspartic acid, proline, glycine, alanine, cystine, leucine and tyrosine were continually decreased during the fermentation of Chungkookjang Koji, arginine and methionine were increased until 48 hours fermentation of Chungkookjang Koji and then decreased gradually. The increase of threonine and serine were fluctuated. Eight kinds of fatty acids were detected from raw soybean, but 10 kinds of fatty acids detected from Chungkookjang Koji. Palmitic, oleic and linoleic acid were identified as the major fatty acid of raw soybean and Chungkookjang Koji, and amounts of those were estimated above 80% of the total fatty acids.