• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.15 no.1
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• pp.1-30
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• 2002

This experimental study was done to research effects of a number of extract on the anti-allergic effect. The results were obtained as follows: 1. In effect of herb-extract on compound $\frac{48}{80}$-mediated histamine release from Evans blue skin assay, Isatis Japonica Miquel, Dictamnus dasycarpus Turcz, Spirodela polyrhiza, Cimicifuga heracleifolia, Bupleurum chinense, Magnolia liliflora, Forsythia koreana, Aster tataricus L., Xanthium strumarium L.(MtOH), Trichosanthes kirilowii, Phellodendron amurense Rupr, Schizonepeta tenuifolia Var, Betula platyphylla show considerable visible anti-allergic effect. In the result of quantification of histamine induced compound $\frac{48}{80}$, Spirodela polyrhiza, Isatis Japonica Miquel, Trichosanthes kirilowii, Bupleurum chinense, Forsythia koreana inhibit histamine release effectively. 2. In effect of Herb-Extract on compound $\frac{48}{80}$-mediated histamine release from RPMC, Spirodcla polyrhiza, Cimicifuga heracleifolia inhibit histamine release effectively. 3. In effect of Herb-Extract on anti-DNP IgE-mediated histamine release from Evansblue skin assay. Spirodela polyrhiza, Cimicifuga heracleifolia(0.1mg/ml). Forsythia koreana, Aster tataricus L., Xanthium strumarium L.(0.1mg/ml), Trichosanthes kirilowii(0.1mg/ml) show considerable visible anti-allergic effect. In the result of quantification of histamine induced anti-DNP IgE, Spiradela polyrhiza, Isatis Japonica Miquel, Trichosanthes kirilowii, Bupleurum chinense, Forsythia koreana inhibit histamine release effectively 4. In the result of genetic manifestative inhibition about the human mast cell-1(HMC-1), Cimicifuga heracleifolia has considerable effect in IL-4 in IL-5, and Tussilage farfara L. has in IL-4. According to the above results, it is suggested that several Herb-Extract have anti-allergic effect.

• The Korean Journal of Zoology
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• v.32 no.4
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• pp.329-338
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• 1989

Present study examined the effect of intermittent versus continuous infusion of progesterone(P) on LHRH release in uiuo from the mediobasal hvpothalamus of ovariectomiEed, estradiol-primed adult rats bearing push-pull cannulae. Three experimental groups were studied: 1) control (perfusion medium only),2) intermittent perfusion of P (10-min on,20-min off, and 3) continuous perfusion of p. p (10 ng/mll was directly infused into the MBH following a 3 hr basal collection. Perfusates were collected at 10 min intents린s on ice and LHRH release was measured by LHRH radioimmunoassav. Cycle detector analysis revealed that the spontaneous HRH output in the control group was pulsatile over a 7 hr push-pull perfusion period. The mean basal LHRH release, pulse amplitude and pl서se period were 0.68 $\pm$ 0.03 ps110 min, 1.15 $\pm$0.08 pg and 60 $\pm$ 9 min, respectivelv. Intermi구eat perfusion of P clearly stimulated the mean LHRH release (pre-P vs post-P: 1.14 $\pm$ 0.18 vs 1.99 $\pm$ 0.53 pg) without changes in LHRH pulse frequency. In contrast to intermittent infusion of p, continuous administration of P faithed to modify LHRH release, since the mean LHRH release and pulse amplitude between pre-P and post-P perfusion urere similar. The in vitro study clearly showed that intermittent, but not continuous administration of P is effective in stimulating LHRH release. Therefore, it appears that rhythmic secretion of P mal be the erective signal for activating the neural LHRH apparatus.

• Journal of Pharmaceutical Investigation
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• v.20 no.2
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• pp.89-95
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• 1990

Ethylcellulose-PEG 4000 film coated on core tablets was investigated as a potential drug delivery system for the controlled release of chlorpheniramine maleate (CPM). The kinetic analysis of the release data indicated that CPM release followed a diffusion-controlled model, where the quantity released per unit area is proportional to the square root of time. The effect of the film composition, CPM concentration, plasticizer concentration and CPM solubility on the release characteristics were examined. The release rate constant increased as CPM concentration increased. It also increased as the PEG 4000 content in the film increased above 10%(w/w), however, it decreased as the PEG 4000 content increased in the concentration range below 10%(w/w). The release rate constant was not affected by the coated weight on the core tablet. The film-coated tablets which contain CPM only in the coated film layer seemed to be a potential oral drug delivery system for the controlled release of CPM.

• Archives of Pharmacal Research
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• v.12 no.2
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• pp.88-93
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• 1989

In order to obtain some informations about the effect of molecular weight on the release rate of drug from drug carrier, two types of poly-L-glutamic acid (PLGA)-cytarabine (ara-C) conjugates, PLGA-ara-C:I and PLGA-ara-C:II, were synthesized using two types of PLGA having different average molecular weight, 43,000 and 77,800, respectively. The PLGA-ara-C conjugates were synthesized by mixed anhydride method and found to be covalently linked. Both types of conjugates charged negatively at biological pH. The pH-dependent release rate of ara-C was observed in both cases, and the release rate was accelerated in basic, acidic conditions (the k values were 0.015 $day^{-1}$ at pH 7.0, 0.024 $day^{-1}$ at pH 5.0, and 0.059 $day^{-1}$ at pH 9.0 in the case of PLGA-ara-C:I) and in the presence of pretense. The time required for the release of 16.5% of ara-C from PLGA-ara-C:I were 8 hr and 144 hr in the presence and absence of protease, respectively. Although both types of conjugates showed similar drug substitution ratio, they showed different release rates. Between the two types of conjugates, PLGA-ara-C:II showed the faster release rate (0.030 vs 0.042 $day^{-1}$ in pH 7.4 phosphate buffer solution at $37^{\circ}C$) and the smaller activation energy for the release of drug (12.5 vs 7.7 Kcal/mol) than PLGA-ara-C:I. The characteristic effect of molecular weight on the release rates of PLGA-ara-C conjugates suggests that the drug release rate might be effectively controlled over a prolonged period of time by the combined use of the different types of PLGA-ara-C conjugates having different molecular weights.

• The Korean Journal of Physiology
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• v.10 no.1
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• pp.55-59
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• 1976

Most investigators have come to stress two different concepts of mechanism controlling renin release; intrarenal baroreceptor theory and the macula densa theory(Vander 1967, Thurau and Masson 1974). In the macula densa theory, the specific macula densa parameter, most commonly suggested as a possible signal, is either the osmolality or the concentration of sodium in the tubular fluid (Thurau 1964, Vander and Miller 1964, Reeves and Sommers 1965). It has been shown that sodium plays an important role in the release of renin either in vivo (Thurau 1964, Vander and Miller 1964, Thurau et al 1972) or in vitro experiments(Oelkers et al 1970, Hammerson et al 1971, Michelakis 1971). On the other hand the osmolality appears to have no effect on the release of renin in vivo (Vander 1967, Thurau and Masson 1974). However, there has been little attempt to study the effect of osmolality on in vitro renin release. We therefore undertook the present investigation to elucidate the effect of osmolality on renin release and to further test the sodium influence upon the release of renin from isolated kidney slice preparations. Isolated renal cortical slices were washed with normal Krebs-Hensenleit bicarbonate buffer solution and incubated for 30 minutes in a medium containing an appropriate concentration of sodium and osmolality. The renin released into the medium was measured by the method of radioimmunoassay(Haber et al 1969). The results obtained are as follows; 1. The release of renin from renal cortical slices was progressively inhibited as the sodium concentration in the medium increased. 2. No significant alteration in renin release was observed when osmolality of the medium was changed. These results suggest that the release of renin from the renal cortical slices is directly affected by the changes in sodium concentration in the medium, but is not influenced by the alterations in osmolality.

• Biomolecules & Therapeutics
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• v.29 no.6
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• pp.630-636
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• 2021

Eupafolin, a constituent of the aerial parts of Phyla nodiflora, has neuroprotective property. Because reducing the synaptic release of glutamate is crucial to achieving pharmacotherapeutic effects of neuroprotectants, we investigated the effect of eupafolin on glutamate release in rat cerebrocortical synaptosomes and explored the possible mechanism. We discovered that eupafolin depressed 4-aminopyridine (4-AP)-induced glutamate release, and this phenomenon was prevented in the absence of extracellular calcium. Eupafolin inhibition of glutamate release from synaptic vesicles was confirmed through measurement of the release of the fluorescent dye FM 1-43. Eupafolin decreased 4-AP-induced [Ca²⁺]_i elevation and had no effect on synaptosomal membrane potential. The inhibition of P/Q-type Ca²⁺ channels reduced the decrease in glutamate release that was caused by eupafolin, and docking data revealed that eupafolin interacted with P/Q-type Ca²⁺ channels. Additionally, the inhibition of calcium/calmodulin-dependent protein kinase II (CaMKII) prevented the effect of eupafolin on evoked glutamate release. Eupafolin also reduced the 4-AP-induced activation of CaMK II and the subsequent phosphorylation of synapsin I, which is the main presynaptic target of CaMKII. Therefore, eupafolin suppresses P/Q-type Ca²⁺ channels and thereby inhibits CaMKII/synapsin I pathways and the release of glutamate from rat cerebrocortical synaptosomes.

• Journal of Pharmaceutical Investigation
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• v.24 no.3
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• pp.33-39
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• 1994

We have studied the effect of loading amount and particle size on the rate of release of 5-fluorouracil (5-FU) from ethylene-vinyl acetate (EVA) matrix. Release rate increased as the loading amount and particle size increase. We also studied the effect of additives (lactose and algin) on the rate of release of 5-FU. Both algin and lactose promoted the rate of release. The ability to increase the rate is in the order of algin>lactose>5-FU. Scanning electron microscope study clearly shows that large cavities and cracks are created. The results imply that, by the proper combinations of the amount of the additive, $EVA_c$ and drug, the rate of drug release can be modulated over a wide range of values.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.391-399
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• 2008

In this paper, we further generalize the work of Lin and Abel to the case of the first and the second order derivatives of energy release rates for two-dimensional, multiply cracked systems. The direct integral expressions are presented for the energy release rates and their first and second order derivatives. The salient feature of this numerical method is that the energy release rates and their first and second order derivatives can be computed in a single analysis. It is demonstrated through a set of examples that the proposed method gives expectedly decreasing, but acceptably accurate results for the energy release rates and their first and second order derivatives. The computed errors were approximately 0.5% for the energy release rates, $3\sim5%$ for their first order derivatives and $10\sim20%$ for their second order derivatives for the mesh densities used in the examples. Potential applications of the present method include a universal size effect model and a probabilistic fracture analysis of cracked structures.

• Biomedical Science Letters
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• v.7 no.3
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• pp.127-131
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• 2001

This study was undertaken to examine the effect of amino acids on anoxia-induced cell injury in rabbit renal cortical slices. In order to induce anoxic cell injury, slices were exposed to a 100% $N_2$ atmosphere and control slices were exposed to 100% $O^2$. Irreversible cell injury was estimated by measuring lactate dehydrogenase (LDH) release and alterations in renal cell function were examined by measuring p-aminohippurate (PAH) uptake. Anoxia caused the increase in LDH release in a time-dependent manner. Glycine and glutathione almost completely prevented anoxia-induced LDH release. Of amino acids tested, glycine and alanine exerted the protective effect against anoxia-induced cell injury. However, asparagine with amide side chain, leucine and valine with hydrocarbon side chain, and basic amino acids (lysine, histidine, and arginine) were not effective. Anoxia-induced inhibition of PAM uptake was prevented by glycine. ATP content was decreased by anoxia, which was not affected by glycine. Anoxia-induced depletion of glutathione was significantly prevented by glycine. These results suggest that neutral amino acids with simple structure exert the Protective effect against anoxia-induced cell injury the involvement of specific interaction of amino acids and cell structure.

• Journal of Pharmaceutical Investigation
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• v.21 no.4
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• pp.237-245
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• 1991

Matrix type silicone rubber devices were designed for long-term implantable drug delivery system. Release controlling agents (RCA), i.e., polypropylene glycol, polyethylene glycol, were employed to control drug release from the devices. The release rate of drug from RCA dispersed silicone matrices was mainly dependent on hydrophilicity-hydrophobicity of drug and RCA. In the case of hydrophilic drug, the release from the RCA dispersed matrix was regulated by swelling kinetics. Especially when the relatively hydrophobic polypropylene glycol was used, swelling control mechanism induced zero-order release kinetics. Whereas, the release of hydrophobic drug was resulted from partition mechanism. The effect of RCA was to increase drug diffusivity.