• Korean Journal of Veterinary Research
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• v.63 no.3
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• pp.30.1-30.8
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• 2023

Metformin is a treatment used widely for non-insulin-dependent diabetes mellitus with few side effects and acts by inhibiting hepatic gluconeogenesis and glucose absorption from the gastrointestinal tract. Lymphoma is one of the most common hematological malignancies in dogs. Chemotherapy is used mainly on lymphoma, but further research on developing anticancer drugs for lymphoma is needed because of its severe side effects. This study examined the anticancer effects of metformin alone and in combination with 2-deoxy-D-glucose (2-DG), a glucose analog, on EL4 cells (mouse T cell lymphoma). Metformin reduced the metabolic activity of EL4 cells and showed an additive effect when combined with 2-DG. In addition, cell death was confirmed using a trypan blue exclusion test, Hochest 33342/propidium iodide (PI) staining, and Annexin V/PI staining. An analysis of the cell cycle and mitochondria membrane potential (MMP) to investigate the mechanism of action showed that metformin stopped the G2/M phase of EL4 cells, and metformin + 2-DG decreased MMP. Metformin exhibited anticancer effects as a G2/M phase arrest mechanism in EL4 cells and showed additive effects when combined with 2-DG via MMP reduction. Unlike cytotoxic chemotherapeutic anticancer drugs, metformin and 2-DG are related to cellular glucose metabolism and have little toxicity. Therefore, metformin and 2-DG can be an alternative to reduce the toxicity caused by chemotherapeutic anticancer drugs. Nevertheless, research is needed to verify the in vivo efficacy of metformin and 2-DG before they can be used in lymphoma treatments.

• The Korean Journal of Pesticide Science
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• v.6 no.1
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• pp.16-24
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• 2002

Research trends in the measurement of foliar uptake of pesticides and the recently proposed action mechanism of the surfactant-induced uptake of pesticides were reviewed with the related reports and studies. Major techniques used in those fields are bioassay, radiotracer techniques with leaves or cuticular membrane. Recently, a new method using Congo Red as a tracer was proposed. The limiting factor in the pesticides uptake into leaves is the waxy layer which consists of the epicuticular and cuticular wax. Physico-chemical parameters such as molar volume, water solubility and partition coefficient of pesticides have limited influences on the pesticide uptake into leaves. Polydisperse ethoxylated fatty alcohol surfactants are well known as the good activator for many pesticides. It is now generally agreed that uptake activation is not related to the intrinsic surface active properties of surfactants such as surface activity, solvent property, humectancy and critical micelle concentration. Recent studies using ESR-spectroscopy revealed that the surfactants have an unspecific plasticising effect on the molecular structure of the wax and cuticular matrix, leading to increased mobilities of pesticides. Penetration of surfactants into waxy layer altered the pesticide mobility in wax and the partition coefficient of pesticide, and then the pesticides penetration into leaves was enhanced temporally. The enhancing effect of surfactant could be significantly different depending on the carbon number of aliphatic moiety and the number of ethoxy group in polyoxyethylene chain of surfactants. It is suggested that the rate of penetration of surfactants should have a significant relationship with the rate of penetration of pesticides.

• The Korean Journal of Pharmacology
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• v.29 no.1
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• pp.107-120
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• 1993

Particulate or soluble stimuli appear to stimulate phagocytic cell's response by the change of $Ca^{2+}$ mobilization and by the activation of protein kinase C. In contrast, it is reported that activation of protein kinase C could attenuate agonist-stimulated elevation of $Ca^{2+}i$ in neutrophils. PAF elicited an increase of $Ca^{2+}i$ in peritoneal macrophages in a dose dependent fashion and $Ca^{2+}$ extrusion was accompanied. PAF-induced elevation of $Ca^{2+}i$ was not affected by TMB-8, verapamil and TTX. TEA stimulated PAF-induced mobilization of $Ca^{2+}i$ and delayed lowering of $Ca^{2+}i$. Five mM EGTA almost completely inhibited PAF-induced mobilization of $Ca^{2+}i$. After the addition of PAF, membrane permeability was markedly increased up to 5 min and then slowly increased. PAF-induced LDH release was slightly decreased by EGTA plus TMB-8. PAF-stimulated superoxide generation was inhibited by EGTA, TMB-8 and verapamil but not affected by TTX and TEA. PAF-induced elevation of $Ca^{2+}i$, increased membrane permeability and superoxide generation were inhibited by IQSP, chlorpromazine and propranolol. PAF-induced LDH release was significantly inhibited by chlorpromazine and minimally decreased by propranolol. After the pretreatment with PMA, the stimulatory effect of PAF on the elevation of $Ca^{2+}i$ and LDH release in macrophages was significantly decreased. These results suggest that PAF may exert the stimulatory action on peritoneal macrophages of mouse by the elevation of $Ca^{2+}i$ and by the activation of protein kinase C. Preactivation of protein kinase C appears to attenuate the stimulatory action of PAF on macrophage response.

• The Korean Journal of Pharmacology
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• v.20 no.1 s.34
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• pp.55-65
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• 1984

Comparative effects of $PGF_{2{\alpha}}$ and ouabain on the isolated rat(Sprague-Dowley) atria were studied. The isolated rat atria were prepared for isometric myography in the isolated organ bath containing Feigen's solution perfused with 95% $O_2$ and 5% $CO_2$, and the pH of the medium was maintained at 7.4. The cumulative concentration-response relationship revealed the positive inotropic effects of both drugs with the higher potency of $PGF_{2{\alpha}}$ and the higher efficacy of ouabain. $PGF_{2{\alpha}}$ showed a positive chronotropic effect, but ouabain showed a tendency of increasing the contraction rate. In low-Ca(1.4 mM) medium, the positive inotropic and chronotropic effect of $PGF_{2{\alpha}}$(by $3{\times}10^{-8}M$) were preponderant $(p<0.05{\sim}p<0.005)$ over those of ouabain(by $3{\times}10^{-3}M$). $Ca^{++}$-addition(cumulative, to 2.8, 4.2, 5.6, and 7.0 mM) into the medium evoked the more sensitive response in the $PGF_{2{\alpha}}$ group than in the ouabain group. In low-K(2.8 mM) medium, the $PGF_{2{\alpha}}a(3{\times}10^{-8}M)$ group and the ouabain$(3{\times}10^{-3}M)$ group showed similar tensions(DT and RT) and contraction rates. And both group showed significantly(p<0.05p<0.01) higher tensions and contraction rates than those of the control group. By the cumulative addition of the $K^+$(to 4.2, 5.6, 7.0 and 8.4 mM), only the DT of the $PGF_{2{\alpha}}$ group was sustained at signifcantly$(p<0.05{\sim}p<0.01)$ higher level than the DT of the control group. The $K^+$-addition inhibited the positive inotropic effect of ouabain significantly (p<0.05). The cumulative addition of lidocaine in high concentrations $(1{\times}10^{-5}\;to\;1{\times}10^{-3}M)$ evoked no significant influence on the intropic activities of $PGF_{2{\alpha}}$ and ouabain, but significant ${\beta}$-blockade with propranolol could not inhibit the positive intropic and chronotropic effect of $PGF_{2{\alpha}}$. In conclusion, it is presumed that $PGF_{2{\alpha}}$ may have some more active mechanism of accelerating the influx of $Ca^{++}$ across the cell membrane of the isolated rat atria as compared with ouabain, and the action site may be located at the cell membrane. As a supposition which needs further investigations, it is presumed that $PGF_{2{\alpha}}$ may have its specific membrane receptors on the atrial muscle or sinus node cells.

• The Korean Journal of Pharmacology
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• v.31 no.1 s.57
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• pp.63-74
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• 1995

It has been known that, during hypoxia, the adrenal medulla is activated to release catecholamines (CA) while hypoxia also inhibits high $K^+$ -induced CA secretion in the cultured bovine adrenal chromaffin cells. The present study was attempted to examine the effect of hypoxia on CA secretion evoked by chlinergic stimulation and membrane-depolarization from the isolated perfused rat adrenal glands and also to clarify its mechanism of action. For this purpose, using the isolated rat adrenal glands, the effects of hypoxia on CA release evoked by nicotinic ($N_1$) and muscarinic ($M_1$) receptor agonists, membrane-depolarizing agent, $Ca^{++}$-channel activator, intracellular $Ca^{++}$-releaser and ACh were determined. Experiments were carried out, perfusing Krebs solution pre-equilibrated with a gas mixture of 95% N_2$ and 5% $CO_2$. Hypoxia was maintained for $3{\sim}4$ hours through the experiments. Hypoxia gradually caused a time-dependent seduction in CA secretion evoked by DMPP ($100{\mu}M$), McN-A-343 ($100{\mu}M$), ACh (5.32 mM), Bay-K-8644 ($10{\mu}M$) and high $K^+$ (56 mM) respectively. How-ever, it did not affect CA secretion evoked by cyclopiazonic acid ($10{\mu}M$). Hypoxia itself also did fail to produce any influence on spontaneous secretory response of CA. These experimental results suggest that hypoxia depresses CA release evoked by both cholinergic stimulation and membrane-depolarization from the isolated rat adrenal medulla, and that this inhibitory activity may be due to the result of the direct inhibition of $Ca^{++}$ influx into the chromaffin cells without any effect on the calcium mobilization from the intracellular store.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.32 no.3
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• pp.189-199
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• 2006

Purpose of study: Partial thickness skin graft is the golden standard regimen for full-thickness skin defect caused by burn or trauma. However, in case of extensive burns of more than 50% of total body surface area, the donor site is not sufficient to cover all defects. As a second choice, allograft, xenograft and synthetic materials have been used to treat skin defect. Among them the amniotic membrane(AM) was used as a biological dressing for centuries because of its potential for wound healing. In this study, quantification of EGF in AM and effect of AM-collagen complex on full thickness skin defects was examined. Materials & Methods: The concentration of EGF in fresh, deep frozen and freeze-dried AM was evaluated by ELISA. EGF-R immunostaining was performed in freeze-dried AM. SD rats weighing 250${\sim}$300g was used for wound healing experiment. Three full thickness skin defects(28mm diameter) were made on dorsal surface of SD rat. The control group was covered by Vaselin gauze and AM-collagen complex and $Terudermis^{(R)}$. was grafted in two other defects. Healing area, Cinamon's score were evaluated before biopsy. Grafted sites were retrieved at 3 days, 1 week, 2 weeks and 4 weeks after operation. H & E and Factor VIII immunohistochemical stain was performed to evaluate the microscopic adhesion and structural integrity and microvessel formation. Results: 1. EGF concentration of fresh, deep frozen and freeze-dried AM showed similar level and EGF-R was stained in epithelial layer of freeze-dried AM. 2. At 4 weeks after grafting, the healing area of AM-collagen and Terudermis group was 99.29${\pm}$0.71% and 99.19${\pm}$0.77 of original size. However, that of control group was 24.88${\pm}$2.90. 3. The Cinamon's score of AM-Collagen and $Terudermis^{(R)}$. group at 4 weeks was 15.6${\pm}$1.26 and 14.6${\pm}$3.13 and that of control group was 3.7${\pm}$0.95. Significant difference was observed among control and experimental groups(p<0.05). 4. Histologic examination revealed that AM protected leukocyte infiltration and epithelial migration was nearly completed at 4 weeks. $Terudermis^{(R)}$. group showed mild neutrophil infiltration until 2 weeks and completion of epithelization at 4 weeks. Control group showed massive leukocyte infiltration until 4 weeks. 5. Microvessels were increased sharply at 1 week and control group at 1 and 4 week showed significant differences with $Terudermis^{(R)}$. group of same interval(p<0.05) but no differences were found with AM group(p<0.05). Conclusion: EGF and EGF-R were well preserved in freeze-dried AM. AM attached to collagen acted as excellent biologic dressing which had similar effect with $Terudermis^{(R)}$. AM showed anti-inflammatory action and healing was completed at 4 weeks after full-thickness skin defect.

• The Korean Journal of Pharmacology
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• v.23 no.2
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• pp.101-111
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• 1987

We investigated the binding properties of $(^3H)$ QNB and $(^3H)$ NMS to mAchR to elucidate the characterstics of mAchR in rat brain by using two different preparations (homogemates & intact brain cell aggregates). The binding properties of both ligands demonstrated high affinity and saturability in both experiments, however $(^3H)$ QNB showed a significantly higher maximal binding capacity than tha ot $(^3H)$ NMS 1. In rat brain homogenates; Displacement of both lignands with several mAchR antagonists resulted in competition curves in accoradnce with the law of massaction for QNB, atropine & scopolamine in thie preparation, also a similar profile was found for the quaternary ammonium analogs of atropine & scopolamine (methyl atropine & methylscopolamine) when $(^3H)$ NMS was used to label the receptors in rat brain. But when these hydrophillic antagonists were used to displace $(^3H)$ QNB, they showed interaction with high- and low-affinity binding sites in brain homogenates. Pirenzepine, the nonclassical mAchR antagonist, was able to displace both ligands from binding sites in this preparation. 2. In intact rat brain cell aggregates; Intact bain cell aggregates were used to elucidate the binding characteristics of $(^3H)$ NMS to mAchR in rat. The magnitude of binding of this ligand was related linearly to the amount of cell protein in the binding assay with a high ratio of total to nonspecific binding. mAchR antagonists displaced specific $(^3H)$ NMS binding according to the law of mass-action, while it was possible to resolve displacement curves using mAchR agonist into high-& low-affinity component. 3. Our results indicate that more hydrophilic receptor ligand $(^3H)$ QNB, displacement experiments in both tissues demonstrated that the lipid solubility of a particulr mAchR ligand might play an important role in determining its profile of binding to the mAchR, and the concentrations of mAchR in rat brain are both on the cell surface (membrane-bound receptor) and in the intracelluar membrane (intermembrane-bound receptor). 4. The results are discussed in terms of the usefulness of dissociated intact rat brain cells in studying mAchR in central nervous system.

• Applied Microscopy
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• v.7 no.1
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• pp.21-43
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• 1977

This experiment was undertaken in order to localize the labeled dbcAMP (dibutyryl cyclic AMP) in oocytes whose development has been suppressed by cold dbcAMP for 6 or 19 hours in vitro. Mouse oocytes were obtained from the ovaries of 3-4 week old A strain female mice, by puncturing the Graafian follicles in the modified Krebs-Ringer bicarbonate salt solution under the dissecting microscope. Those oocytes which have intact germinal vesicle were cultured in the basic culture medium supplemented with 0.4% bovine serum albumin (BSA). Cultivation of the oocytes was carried out in a microtube developed by Cho (1974). The cultures were then incubated in a humidified 5% $CO_2$ incubator maintained at $37^{\circ}C$ for 6 or 19 hours (Donahue, 1968). DbcAMP was added to culture medium for a final concentration of 100ug/ml, and $^3H-dbc$ AMP (specific activity 13 Ci/mM) for a final concentration of $40{\mu}Ci/ml$ was also added to the medium. For electron microscopic autoradiography, those oocytes recovered from the culture were washed with phosphate buffer (pH 7.4), and immediately prefixed in a 2.5% glutaraldehyde overnight and postfixed for 2 hours at $4 ^{\circ}C$ in 1% osmium tetroxide in phosphate buffer with pH 7.4 (Palade, 1952). After fixation, the materials were dehydrated in graded alcohol series and embedded in Epon 812 mixture based on the standard procedures (Luft, 1961). The thin sections $600-700{\AA}$ thick were mounted on the grids of 200 meshes. The grids containing sections were coated with a nuclear emulsion Kodak NTB-3 and stored in a cold dark box (at $4^{\circ}C$) for 3 weeks. After exposure, the samples were developed with Kodak D-19 and stained with uranyl acetate and lead citrate. Routine observation was made with Hitachi HU-11E electron microsocope. The results of the observation were as followings: 1. It was found that the labeled dbcAMP penetrated the egg plasma membrane and dispersed at random in the cytoplasm. 2. It was also observed that most of the labeled dbcAMP was attached to microfibrillar lattices portion of the oocyte cytoplasm. There fore, it is presumed that the receptor of the dbcAMP is localized in the microfibrillar lattices of the oocyte. 3. It also seems that some other cell organells such as mitochondria, Golgi complex, cortical granules are not directly related to the action of the dbcAMP. 4. The labeled dbcAMP was neither observed in the membrane nor in the nucleus. Therefore, it seems that there is no relationship between the concentration of dbcAMP and the nuclear membranous permeability. 5. There was no difference in number of dbcAMP particles when oocytes were cultured for 6 hours and 19 hours. 6. However, it was observed that, in same of the oocytes suppressed in germinal vesicle by dbcAMP for 19 hours, cell organells were moved and concentrated to a small portion of the cytoplasm, and that the morphology of the organells greatly changed to an abnormal. form. Therefore, it is supposed that those oocytes were in the process of degeneration. From the above results, it is expected that dbcAMP penetrated the egg membrane and was bound to the receptor which seems to be located in the microfibrillar lattiees portion, and that this dbcAMP-receptor complex inhibited some enzyme system of the oocytes which are essential for the germinal vesicle breakdown.

• Parasites, Hosts and Diseases
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• v.33 no.4
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• pp.349-356
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• 1995

We have investigated the action of sodium nitrite on the growth and morphologic changes of T uaginolis and on the treatment of subcutaneous abscess by trichomonad in mice. Sodium nitrite inhibited the growth of metronidazole-sensitive KT9 isolate and metronidazole-resistant CDC85 strain of T vcsinalis as concentration of 6 mM and 10 mM respectively Intraperitoneal injection of sodium nitrite (70 ㎍, 100 ㎍, 130 ㎍/g body weight) did not reduce the size of abscess produced by subcutaneous inoculation of T uasinnlis in mice. T uosinnlis, treated with sodium nitrite at concentration giving about 50% inhibition of growth, showed fissures, many vacuoles and electron-translucent zone in the cytoplasm by transmission electron microscopy. In the case of CDC85 treated with 9 mM sodium nitrite, hydrogenosomal matrical change , destruction of hydrogenosomal membrane, autophagic vacuoles, disappearance of Golgi complex and polysome were notably observed . With above results, it is assumed that sodium nitrite inhibits the growth of metronidazole-sensitive and - resistant strains of T. ucsinalis and induces the morphological changes of 7 uusinalis although it does not affect in reducing of abscess size by vagiginalis in mice.

• The Korean Journal of Physiology
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• v.23 no.2
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• pp.277-289
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• 1989

The effects of noradrenaline on the contractile and electrical activities were investigated using the circular muscle strips with intact mucosa prepared from the antrum and fundus of guinea-pig stomach. Electrical responses of circular muscle cells were recorded using glass capillary microelectrodes filled with 3 M KCI. All experiments were performed in tris-buffered Tyrode solution which was aerated with 100% $O_2\;and\;kept\;at\;35^{\circ}C$. The results obtained were as follows: 1) The spontaneous contractions recorded from the antral and fundic circular muscle strips with intact mucosa were suppressed dose-dependently by the application of noradrenaline, whereas those recorded from the mucosa-free strips were potentiated in a dose-dependent manner. 2) The inhibitory influences on the contractile activities in the normal intact strips were developed via both ${\alpha}-adrenoceptors\;and\;{\beta}-adrenoceptors$, while the excitatory influences in the mucosa-free strips resulted from the strong excitatory effect via ${\alpha}-adrenoceptors$ and the weak inhibitory effect via ${\beta}-adrenoceptors$. 3) Noradrenaline produced hyperpolarization of membrane potential, and increased the amplitude and the maximum rate of rise of slow waves in the mucosa-free strips of antral and fundic circular muscle. 4) Apamin blocked the appearance of the component of initial suppression of spontaneous phasic contractions observed in the mucosa-free strips of antral circular muscle after the application of noradrenaline. 5) The inhibitory influences on the contractile activities in the normal strips with intact mucosa remained unaffected even in the strip with separate mucosa, in which mucosa and muscle layer were mechanically disconnected . From the above results, following conclusions could be made. (1) There are no regional differences between the effects of noradrenaline on the antral circular muscle and those on the fundic circular muscle. (2) Excitatory responses to noradrenaline observed in the mucosa-free strip result from the dominant ${\alpha}-excitatory$ and tile weak ${\beta}-inhibitory$ action of noradrenaline. (3) Inhibitory responses to noradrenaline in the normal strips with intact mucosa develop via both ${\alpha}-inhibitory\;and\;{\beta}-inhibitory$ actions.