• Korean Journal of Veterinary Research
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• v.39 no.4
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• pp.702-709
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• 1999

The present study was performed to elucidate the effects of extracellular $Ca^{2+}$ on contractile responses in isolated porcine coronary artery ring using by perivascular nerve stimulation (PNS). Especially, the study was focused on the source of $Ca^{2+}$ on $P_{2X}$-purinoceptor mediated muscle contraction which one of $P_2$-purinoceptor subtypes. The following results can be drawn from these studies : 1. The phasic contractions induced by PNS were inhibited with muscarinic receptor antagonist, atropine ($10^{-6}M$). 2. The phasic contractions induced by PNS were significantly inhibited by sequential treatment with atropine and adrenergic neural blocker, guanethidine ($10^{-6}M$). 3. The phasic contractions induced by PNS were inhibited with $P_{2X}$-purinoceptor desensitization by repetitive application of $\alpha$,$\beta$-Me ATP ($10^{-4}M$). 4. The phasic contractions induced by PNS were so weakened in calcium-free medium. 5. The phasic contractions induced by PNS were inhibited with calcium channel blocker, verapamil ($10^{-6}{\sim}5{\times}10^{-6}M$). 6. The phasic contractions induced by PNS on pretreated with verapamil ($10^{-6}{\sim}5{\times}10^{-6}M$) were not changed by $\alpha$,$\beta$-Me ATP ($10^{-4}M$). These results demonstrate that the neurogenic phasic contractions induced by PNS are due to adrenergic-, cholinergic- and $P_{2X}$-purinergic receptors and the origin of $Ca^{2+}$ on $P_{2X}$-purinoceptor mediated muscle contraction is extracellular $Ca^{2+}$ through plasmalemmal $Ca^{2+}$ channels.

• Korean Journal of Veterinary Research
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• v.37 no.1
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• pp.103-110
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• 1997

The experiments were carried out to elucidate the relationships between neurogenic effects of electrical transmural nerve stimulation and effect of adenosine 5'-triphosphate(ATP) to purinoceptor on the urinary bladder smooth muscle of pig. The results were as follows : 1. The contractile responses induced by electrical transmural nerve stimulation(10V or 20V, 0.5msec, 10sec) were the frequency(2~64Hz) dependent manner. 2. The contractile response induced by carbachol was responsed with a dose-dependent manner and the maximum contractility was $10^{-4}M$. 3. The contractile responses induced by ATP were increased in a dose-dependent manner ($10^{-5}{\sim}10^{-3}M$). 4. The contractile response induced by electrical transmural nerve stimulation(10V, 2~32Hz, 0.5msec, 10sec) was partially blocked by the treatment with atropine($10^{-5}M$), and was powerfully inhibited by 3 times of addition with ATP($10^{-5}M$). 5. The contractile response induced by electrical transmural nerve stimulation(10V, 2~32Hz, 0.5msec, 10sec) was partially blocked by the treatment with atropine($10^{-5}M$), and was completely blocked by the desensitization of the $P_{2X}$-purinoceptor using ${\alpha}$, ${\beta}$-methylene ATP($5{\times}10^{-5}M$). These results suggest that purinergic nerve was innervated, and ATP and acetylcholine was released by the electrical transmural nerve stimulation in urinary bladder smooth muscle of pig.

• Microbiology and Biotechnology Letters
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• v.13 no.2
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• pp.119-127
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• 1985

A series of Escherichia coli mutants were exmined for ability to convert glucose and ammonium salts into phenylalanine. This enabled the biochemical changes having major. effects on phenylaianine yield, and interactions between mutations, to be identified. Changes to the common pathway of aromatic biosynthesis having a major effects include desensitization of the first enzyme (3-deoxy-D-arabinoheptulosonate synthase) to end-product inhibition, and removal of repression of enzyme synthesis. It is suggested that the 3-deoxy-D-arabino-heptulosonate synthase Phe isoenzyme has a more important effect on yield. Similarly, removal of repression and end-product inhibition on the phenylalanine terminal pathway increased yield, and changes to both common and branch pathways were synergistic. Blockage of the typrosine and tryptophan pathways had minor effects on phenylalanine yield, and a mutation affecting aramatic amino acid transport (aroP) decreased yield. With multiple-mutation strains hish specific rates of product formation (ie 0.1-0.17g phenylalanine/g cells/h) were obtained.

• Archives of Pharmacal Research
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• v.10 no.4
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• pp.212-218
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• 1987

Intact brain cell aggregates were dissociated from adult rat brains without cerebellum using a sieving technique. This proparation was used to elucidate the binding characteristics of agonist to muscarinic acetylcholine receptors (mAchR) in brain. Incubation of cells with carbamylcholine (carbachol) was shown agonist-induced receptor down-regulation depending on the concentration of agonist, not depending on the incubation time. This effect of carbachol was due to a reduction in the maximal binding capacity ($B_{max}$) to the mAchR without decreasing the affinity of the remaining receptors in incubation at 37.deg.C but was not apparent inincubation at $15^{\circ}}C$In addition, it was abolished when the receptors were blocked by atropine. The decline in ($^3H$)N-methylscopolamine (($^3H$)NMS) binding induced by agonist was reflected as a significant reduction in the receptor density with no change in receptor affinity, suggesting that 'true' receptor down-regulation takes place. Moreover, when the receptors were labeled with the lipophilic antagonist ($^3H$) quinuclidinyl benzilate (($^3H$) QNB) insted of the hydrophilic ligand ($^3H$)NMS, the magnitude of the observed receptor down-regulation was significantly lower in case of the former than the latter. This suggested that exposure of intact brain cells to muscarinic agonists might induce a slight degree of accumulation of receptors in intracellular sites before the receptors are actually degraded.

• Molecules and Cells
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• v.27 no.2
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• pp.167-173
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• 2009

The classical type of transient receptor potential (TRPC) channel is a molecular candidate for $Ca^{2+}$-permeable cation channels in mammalian cells. Because TRPC4 and TRPC5 belong to the same subfamily of TRPC, they have been assumed to have the same physiological properties. However, we found that TRPC4 had its own functional characteristics different from those of TRPC5. TRPC4 channels had no constitutive activity and were activated by muscarinic stimulation only when a muscarinic receptor was co-expressed with TRPC4 in human embryonic kidney (HEK) cells. Endogenous muscarinic receptor appeared not to interact with TRPC4. TPRC4 activation by $GTP{\gamma}S$ was not desensitized. TPRC4 activation by $GTP{\gamma}S$ was not inhibited by either Rho kinase inhibitor or MLCK inhibitor. TRPC4 was sensitive to external pH with $pK_a$ of 7.3. Finally, TPRC4 activation by $GTP{\gamma}S$ was inhibited by the calmodulin inhibitor W-7. We conclude that TRPC4 and TRPC5 have different properties and their own physiological roles.

• The Korean Journal of Physiology
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• v.24 no.2
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• pp.305-317
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• 1990

The present study was performed to investigate modification in the electrophysiological characteristics of cat dorsal horn cells during neurogenic inflammation induced by mustard oil. The results obtained were summarized as follows: 1) Following subcutaneous injection of mustard oil the majority of wide dynamic range (WDR) cells (10/15 units) showed enhanced responses (80%) to brush, while the responses to all types of mechanical stiumli were enhanced in 3/15 units. One cell was further activated by pinch and the another was not affected at all after induction of inflammation. 2) The sensitization of WDR cell was resulted from subcutaneous injection of mustard oil either inside or outside of the receptive field (RF), whereas the spontaneous activity increased only after mustard oil was injected inside of the RF. 3) In the animal with inflammation the responses of high threshold (HT) cell to noxious stimulus were not altered, while HT cell responded to such mechanical stimulus as pressure which was usually ineffective in normal animals. 4) After induction of inflammation, low threshold (LT) cell appeared to be converted to WDR cell, showing responses not only to brush but also to pressure and pinch. 5) The mustard oil-induced inflammation enhanced responses of WDR and HT cells to the thermal stimuli and also resulted in a pronounced after-discharge in WDR cells. 6) After subcutaneous injection of lidocaine, the increased background activity of WDR cells due to inflammation was almost completely abolished. 7) A subcutaneous injection of mustard oil inside of the RF invariably desensitized the dorsal horn cells which receive sensory inputs from the inflamed RF. From the results of Present study it was revealed that a neurogenic inflammation induced by mustard oil resulted in an enhancement of responses of cat dorsal horn cells to mechanical and thermal stimuli.

• Korean Journal of Transplantation
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• v.32 no.4
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• pp.92-103
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• 2018

Background: Currently, trimethoprim-sulfamethoxazole is used for Pneumocystis jirovecii pneumonia (PJP) prophylaxis, but it is associated with frequent adverse effects. This study evaluated the efficacy and safety of the current protocol and proposes an individualized risk-based prophylaxis protocol. Methods: The PJP incidence and risk factors during the first 6 months (early PJP) and afterwards (late PJP) was assessed in renal transplant recipients with (prophylaxis group) and without (no-prophylaxis group) 6-month PJP prophylaxis. Results: In 578 patients, there were 39 cases of PJP during a median follow-up of 51 months. Renal adverse events were encountered frequently during trimethoprim-sulfamethoxazole prophylaxis, leading to premature discontinuation. Patients without the prophylaxis had a significantly higher incidence of early PJP (n=27, 6.6%) compared to patients with the prophylaxis (n=0). The incidence of late PJP was 2.2%, without between-group differences. The factors associated with early PJP were preoperative desensitization and acute rejection within 1 month, whereas late PJP was associated with age, deceased donor transplant, and acute rejection requiring antithymocyte globulin treatment. Conclusions: Based on the simulation results of several risk-based scenarios, the authors recommend universal prophylaxis up to 6 months post-transplant and extended selective prophylaxis in patients aged ${\geq}57$ years and those with a transplant from deceased donors.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.2
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• pp.222-229
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• 2024

As the operating condition for the penetrating missile has been more advanced, the survivability of main charge has been strongly required when the warhead impacts the target. Lots of efforts to desensitize explosives such as the development of insensitive molecular explosives or optimizing plastic-bonded explosives(PBX) systems has been made to enhance the survivability of main charge. However, these efforts face their limits as the weapon system require higher performance. Herein, we suggest a new strategy to secure the survivability of main charge. We applied structurally supportable aluminum honeycomb(HC) structure to cast PBX. The aluminum HC structure reinforces the mechanical strength of cast PBX and helps it to withstand external pressure without the reaction like detonation. In this study, impact resistance character, shock sensitivity and internal blast performance of PBXs reinforced with HC structure were investigated according to the application of aluminum HC structure. The newly suggested aluminum HC structure applied to cast PBX was proved to be a promising manufacturing method available for high-tech weapon systems.

• Tuberculosis and Respiratory Diseases
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• v.45 no.1
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• pp.77-89
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• 1998

Background: Genetic and environmental factors are known to affect the incidence and severity of asthma. Stimulation of $\beta_2$-Adrenergic Receptor ($\beta_2$AR) results in smooth muscle relaxation, leading to decrease in resistance of airflow. The gene encoding the $\beta_2$AR has recently been seguenced. The $\beta_2$AR genotype at the polymorphic loci of codons 16, 27, 34, and 164 was known to cause changes in the amino acids. The relationships between the structure of the $\beta_2$AR and its functions are being elucidated. Purpose : The gene encoding the $\beta_2$AR was carried out to assess the frequency of polymorphisms in bronchial asthma, to determine wheather these polymorphisms have any relation to the severity, or nocturnal symptoms in bronchial asthma. Methods: The subjects studied were 103 patients with bronchial asthma, which consisted of 30 mild episodic, 32 mild persistent, 17 moderate, and 24 severe asthma patients. The polymorphisms of the $\beta_2$AR gene were detected by mutated allele specific amplification (MASA) method at the codons 16,27,34, and 164. Results: The most frequent polymorphism was arginine 16 to glycine. The other two polymorphisms, valine 34 to methionine and glutamine 27 to glutamic acid occured in 11 and 6 patients respectively. The polymorphism of threonine 164 to isoleucine was not found in our enrolled patients. The homozygous polymorphism of $\beta_2$AR gene was found in only arginine 16 to glycine (12.6%). The heterozygous polymorphisms of $\beta_2$AR gene were in arginine 16 to glycine, valine 34 to methionine, and glutamine 27 to glutamic acid, as 65.1 %,10.7%, and 5.8% respectively in asthma patients. The presence of agrginine 16 to glycine heterozygous or/and homozygous polymorphism was associated in severe asthma (p=0.015), but there was no association between the other three polymorphisms and the severity of asthma. The frequency of the $\beta_2$AR gene polymorphisms was no relation in nocturnal asthma as compared with non-nocturnal asthma. Conclusion: The arginine 16 to glycine polymorphism of the $\beta_2$AR gene is the most frequently found in asthma patients and association with severe asthma. But there was no association between the polymorphism of the $\beta_2$AR gene and nocturnal asthma.

• Applied Microscopy
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• v.24 no.3
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• pp.23-33
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• 1994

It is well known that dichlorvos (DDVP), an organophosphate insecticide in common use, is so easily and rapidly hydrolyzed and excreted that it has usually little toxic effect on human body. In these days, however, it is widely used as an industrial and domestic insecticide and as an anthelmintic agent for animals, so that the accident of chemical poisoning occurs frequently. DDVP acts as a powerful inhibitor of carboxylic esterase, which can cause accumulation of acetylcholine at the synapses so paralysis of muscle and the transmission failure in cholinergic synapses dueing to desensitization of acetylcholin receptor may occure. Moreover accumulation of the acetylcholine brings about the elevation of the cyclic-AMP, which alters the cellular metabolisms of nucleic acid, carbohydrate, protein and lipid. Present study has undertaken to investigate the cardiotoxic effect of DDVP by electron microscopic study. A total of 30 Sprague-Dawley strain rats, weighing about 250gm were used as experimental animals. 2mg/kg/day of DDVP is intraperitonealy injected 3 times with intervals of every other day. On 1 day, 3 days, 5 days, 7 days and 14 days after drug administration, the animals were sacrified by cervical dislocation. Left ventricular cardiac muscles were resected and sliced into $1mm^3$. The specimens were embedded with Epon 812 and prepared by routine methods for electron microscopical observation. All preparations were stained with lead citrate and uranyl acetate and then observed with Hitachi-600 transmission electron microscope. The results were as follows: 1. In the cardiac muscle of DDVP treated rats, mitochondria with disorganized double membrane and mitochondrial crista, and vacuole formation in mitochondrial matrix were observed. But structures of mitochondria were recovered to normal in 14 days group. 2. In the cardiac muscle of DDVP treated rats, cisternae of sarcoplasmic reticulum were dilated and sacculated. But these changes were recovered to normal in 14 days group. 3. In the cardiac muscle of DDVP treated rats, glycogen particles around damaged myofibrils were decreased. But amount of glycogen particles were restored in 14 days group. 4. In the cardiac muscle of DDVP treated rats, disruption and discontinuation of myofilaments and disorganization of Z-disc were observed. But the structures of myofibrils were recovered to normal in 14 days group. It is consequently suggested that DDVP would induce the reversible degenerative changes on the ultrastructures in cardiac muscle of rat.