Landsat TM자료상의 임상분류 정확도 향상에 관한 연구 : 최대 우도법과 인공 신경망 기법의 비교 중심으로

학위논문(석사)--서울대학교 대학원 :산림자원학과,1997.Maste

Studies on the cardiac uptake of catecholamines

의학과/박사[한글] [영문] Loewi's classical experiments in 1921 which demonstrated the presence of sympathetic neurotransmitter in the heart, have laid the groundwork for understanding of the chemical transmission of sympathetic nerve impulses. It is now well established that the transmitter of sympathetic nerve is identical with norepinephrine (Barger and Dale, 1911; Bacq, 1934; Euler, 1948). During the following decades a considerable amount of interest was directed to the synthesis, storage, release and metabolism of catecholamines both in the sympathetic nerve and in the adrenal medulla. A considerable proportion of the catecholamines in the adrenergic nerve is kept in intracellular particles and these storage granules have a very high content of adenine nucleotides (Falk et al.,1956; Schumann, 1958b; Potter and Axelrod, 1963b). The remarkable constancy of the molar catecholamine/adenine nucleotide relationship under various conditions has led to the proposition that the catecholamine stored in the granules actually form a complex with adenine nucleotides and some third component, probably intragranular protein (Carlsson and Hillarp, 1956a; Blaschko et al., 1957). Within these granules which contain the enzyme dopamine beta-oxidase, the last step in the biosynthesis of norepinephrine (the beta-hydroxylation of dopamine), has been shown to occur (Potter and Axelrod, 1963b). On the other hand, the decarboxylation of dopa takes place in the cell sap (Masuoka et al., 1958). While catecholamines are synthesized and stored locally both in adrenergic nerves and in the adrenal medulla, recent investigations have clearly shown that they are also released from the postganglionic sympathetic nerve endings and a part of these released norepinephrine as well as injected norepinephrine is to a variable extent taken up into tissue stores (Raab and Gigee, 1955; Muscholl, 1960). Furthermore, the existence of a highly efficient mechanism for uptake and retention of circulating catecholamines in the tissues has been demonstrated by following the fate of intravenously injected radioactively labeled epinephrine (Axclrod et al., 1959) and norepinephrine (Whitby et al., 1961). Nevertheless of these evidences, little is known about the uptakeability of several catecholamines which are structurally analogous to norepinephrine or epinephrine. In this respect, it was of interest to examine the nature and the relative potency of uptake among these catecholamines when the uptake was actually involved in the heart and to explore the role of enzymes (MAO and COMT) in the process of catecholamine uptake. In addition, it was also designed to determine the catecholamine uptake by chronically denervated heart. The experiments were conducted on the isolated atria. The catecholamine content in atria was determined by the spectrophotofluorometric procedure described by Shore and Olin (1958) and the monoamine oxidase activity was determined colorimetrically according to the procedure of Green and Haughton (1961), using mitochondria prepared from cardiac homogenates in 0.25 M sucrose. Results 1. The intraperitoneal injection of reserpine (3mg/kg) into rabbits 24hr prior to study, abolished the response of the atria from these animals to tyramine (5×10**-5 M) a concentration which produced a marked increase in the rate and contractile amplitude of atria from normal rabbits. The atria from rabbits pretreated with reserpine were exposed for 10 min to various concentrations of norepinephrine. Forty-five min after removal of the bathing fluid containing norepinephrine and following repeated exposure to fresh bathing fluid, the response of atria to 5×10**-5 M of tyramine was partly restored. Exposure to concentrations of 3×10**-6 M or greater of norepinephrine increased slightly, but significantly the catecholamine content. Also, the magnitude of the restored response to tyramine and the increase of catecholamine content of the atria appeared to depend on the concentration of norepinephrine to which the atria were exposed. 2. Atria from rabbits pretreated with reserpine were exposed to various concentrations of epinephrine, isoproterenol or alpha-methylnorepinephrine (cobefrine) for 10 min and their respinse to tyramine were then determinded. Epinephrine partially restored the response to tyramine but the magnitude of the response was much smallar than that following exposure to norepinephrine. After treatment with isoproterenol it was not possible to demonstrate any restoration of the response to tyramine. Cobefrine, however, produced more striking restoration of the response to tyramine than did norepinephrine. 3. Before exposure of the atria from reserpinized rabbits to norepinephrine they were incubated in SKF-385 (10**-5 M) for 30 min. The response of these atria to tyramone was compared with that observed with atria which were exposed to the same concentration of norepinephrine but not SKF-385. Tyramone produced a more marked increase in contractile amplitutue of atria which were treated with SKF-385 before exposure to norepinephrine than those exposed to norepinephrine only. JB-516 (10**-4 M) and iproniazid (10**-3 M) significantly enhanced the respone to tyramine produced by prior exposure to norepinephrine. SKF-385, JB-516, and iproniazid significantly increased the amount of norepinephrine accumulated by the atria. Inhibitory activities of SKF-385, JB-516 and iproniazid in the concentrations employed in these experiments, on the MAO of mitochondria prepared from homogenates of rabbits hearts were determined. The magnitude of cardiac MAO inhibition appears to be related to the magnitude of the enhancement of accumulation of norepinephrine produced by these MAO inhibitors. 4. Atria from reserpine pretreated rabbits were exposed to SKF-385, JB-516 or iproniazid for 30 min and then to cobefrine for 10 min. Forty-five min after removal of cobefrine from the bath and following repeated changes of the bathing fluid, the response of atria to tyramine was compared to that of atria treated identically except that a MAO inhibitor was not added prior to the cobefrine. Nether SKF-385, JB-516 nor iproniazid had an effect on the restoration by cobefrine of the response to tyramine. 5. Before exposure of the atria from reserpinzed rabbits to norepinephrine they were incubated in pyrogallol (3×10**-5 M) for 30min. The response of atria to tyramine was compared to that of atria treated identically except that and the content of atrial catecholamine were practically same as those observed in the atria prior to administration of pyrogallol. 6. Pretreatment of the atria with bretylium (5×10**-4 M) for 30 min markedly inhibited their uptake of catecholamine following exposure to norepinephrine. 7. Bilateral sympathectomy in cats 15 days prior to study, markedly depleted the myocardial catecholamine content and abolished the response of the atria from these animals to tyramine. The exposure of norepinphrine to the atria failed to restore both the cardiostimulant action of tyramine and to increase the catecholamine content of these atria. From the above results, it is obvious that the catecholamines, when added in vitro to isolated atria pretreated with reserpine, cause the restoration of cardiostimulant response to tyramine and the increase of cardiac catecholamine contents. Furthermore it may be concluded that MAO and the intact sympathetic nerve play an important role in the accumulation of norepinephrine by the heart, thereby regulating the level of cardiac catecholamines.restrictio

Surface Modification of Magnetic Nanoparticles for Bio-application

MasterMagnetic nanoparticles (MNPs) have been intensively investigated for in vitro and in vivo applications such as a contrast agent for magnetic resonance imaging and magnetically guided drug delivery vehicles due to their unique magnetic properties, biocompatibility and lack of toxicity. Also, they can be served as magnetic separation platform for specific biomolecules. The magnetic separation of specific compound is more efficient and convenient than other separation method. To achieve efficient and practical MNP-based bioseparation, MNPs should have high colloidal stability in physiological condition and minimal non-specific adsorption with biomolecules except target molecules. In this work, synthesis and surface modification of MNPs were described. At first, the fabrication of silica-shell-coated magnetic nanoparticle cluster (SMNC) and successive surface engineering onto SMNC to produce surface-modified SMNC with zwitterionic and primary amine ligands (SMNC-ZW/Am) were showcased. SMNC-ZW/Am is passivated by zwitterionic ligands for improved colloidal stability and reduced non-specific adsorption, and primary amine ligands for simple conjugation with biomolecules. The colloidal characteristics, based on the hydrodynamic size and zeta potential, of SMNC-ZW/Am could be flexibly tuned by controlling the relative amount of zwitterionic and primary amine ligands. SMNC-ZW/Am showed enhanced colloidal stability in high salt concentration and broad pH range rather than did bare SMNC. In addition, non-specific adsorption with biomolecules onto SMNC-ZW/Am surface was significantly suppressed owing the zwitterionic ligands. Reduced non-specific adsorption was confirmed using photoluminescence based protein adsorption assay. Bioconjugation capability of SMNC-ZW/Am could be achieved by using primary amine groups on SMNC-ZW/Am surface, which allowed facile bioconjugation with biotin. Using streptavidin bead and streptavidin-conjugated quantum dot assay, we confirmed that biotins could be successfully conjugated onto surface of SMNC-ZW/Am, and this bioconjugation capability onto colloidal SMNCs with reduced non-specific adsorption should be useful as magnetically-controllable nanosubstrate. Using these surface-modification strategies with zwitterionic moieties, MNPs could be empowered to have higher colloidal stability and more readily conjugated with biomolecules as highly reproducible and useful nanoplatform in various other types of bioseparation and bioanalytical applications. Also, MNPs can be also embedded in various platforms including polymer matrix and mesoporous silica, which provides the advantages of post-functionalizations. The introduction of MNPs to various platforms requires the surface modification to the appropriate type of the ligands. Through the ligand exchange, the MNPs that can be dispersed in aqueous phase and interact with cucurbit[6]uril polymer nanocapsule (CB-PN) platform were developed. CB-PN shows hollow and spherical structure that consists of the disk-shaped molecules with a cavity. The CB-PN can be served as a platform where various nanoparticles are introduced on the surface for many applications. MNPs were initially synthesized in organic solvent using thermal decomposition method for their monodispersity and for the desired size (for high MRI contrast). One phase ligand exchange was conducted with the synthesized MNPs using two hydrophilic ligands; 3,4-dihydroxyhydrocinnamic acid (DHCA) and DHCA-derivative (spermidine) molecule. The amine group of spermidine could interact with the cucurbit[6]uril. The DHCA-spermidine molecules on the surface of MNPs were used as an anchor to connect CB-PN. The ligand-exchanged MNPs have the dispersion stability in aqueous phase and sufficient interaction to link the CB-PN through the method of simple mixing between CB-PN and MNPs, which was confirmed by the measurement of dynamic light scattering and transmission electron microscopy. On the magnetic properties of MNPs, the SMNC-ZW/Am and MNPs@CB-PN could be potential candidates for biological applications such as bioseparation platform and magnetic resonance imaging

Metal oxide film coating method using solution process

본 발명은 금속 알콕사이드 및 유기물을 혼합하여 금속-유기물 전구체 용액을 준비하는 제 1 단계; 입자가 분산된 용매에 상기 금속-유기물 전구체 용액을 첨가하여 상기 입자 표면에 금속-유기물 전구체 흡착막을 형성하는 제 2 단계; 및 상기 금속-유기물 전구체 흡착막이 형성된 입자를 가열하여 표면에 금속 산화물 막이 형성된 입자를 형성하는 제 3 단계; 를 포함하고, 상기 금속 산화물 막의 두께가 목표하는 두께에 도달할 때까지 상기 제 2 단계 및 제 3 단계를 교대 반복하여 수행하는 것을 특징으로 하는 금속 산화물 막 코팅 방법을 제공한다

HIGHLY EMISSIVE SHORT WAVE INFRARED NANOPARTICLES AND METHOD FOR PREPARING THE SAME

본 발명은 E1의 밴드갭 에너지를 갖는 코어; 상기 코어 상에 형성되고 E2의 밴드갭 에너지를 갖는 중간층; 및 상기 중간층 상에 형성되고 E3의 밴드갭 에너지를 갖는 외부층을 포함하고, 상기 E2의 크기는 상기 E1 및 E3의 크기보다 작은 것을 특징으로 하는 단파 적외선 발광 나노입자를 제공한다. 본 발명에 따르면 효율 및 구동 수명이 향상되고 용액공정으로 제조 가능한 태양전지를 제공할 수 있다

HIGHLY EMISSIVE SHORT WAVE INFRARED NANOPARTICLES AND METHOD FOR PREPARING THE SAME

The present invention provides shortwave infrared ray emitting nanoparticles including a core having band gap energy of E1; an intermediate layer that is formed on the core and has band gap energy of E2; and an outer layer that is formed on the intermediate layer and has band gap energy of E3, in which the size of the E2 is smaller than the size of the E1 and the size of the E3. According to the present invention, it is possible to provide a solar cell which is improved in efficiency and life span and can be produced by a solution process

Manufacturing method of polymer composite material for mechano luminescence lighting and the composite material thereof

본 발명은 특정 재료에 국한되지 않고 다양한 재료로부터 기계발광 소재를 만들어 낼 수 있도록 하는 기계발광용 대전발광물질 고분자 복합 소재 제작 방법 및 그 복합 소재에 관한 것으로서, 본 발명의 일 실시예는, 응력에 의한 정전 에너지에 의해 발광하는 발광물질; 상기 응력에 의해 대전되도록 상기 발광물질의 외부면에 형성되는 마찰대전막; 및 상기 마찰대전막이 형성된 상기 발광물질들을 지지하며 응력을 상기 마찰대전막에 전달하여 상기 마찰대전막을 대전시키는 고분자기질;을 포함하여 구성되는 것을 특징으로 하는 기계발광용 고분자 복합소재를 제공한다

Size-tunable Synthesis of Ag2S Nanoparticles and Their Size-dependent Cation Exchanges with In3+ Ions

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Surface Modification of Iron Oxide Nanoparticles and Introduction to Cucurbit[6]uril Polymer Nanocapsule Platform

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