• Parasites, Hosts and Diseases
• /
• v.42 no.4
• /
• pp.185-193
• /
• 2004

Toxoplasma gondii is an obligate intracellular protozoan parasite, which invades a wide range of hosts including humans. The exact mechanisms involved in its invasion are not fully understood. This study focused on the roles of $Ca^{2+}$ in host cell invasion and in T. gondii replication. We examined the invasion and replication of T. gondii pretreated with several calcium modulators, the conoid extrusion of tachyzoites. Calmodulin localization in T. gondii were observed using the immunogold method, and $Ca^{2+}$ levels in tachyzoites by confocal microscopy. In light microscopic observation, tachyzoites co-treated with A23187 and EGTA showed that host cell invasion and intracellular replication were decreased. The invasion of tachyzoites was slightly inhibited by the $Ca^{2+}$ channel blockers, bepridil and verapamil, and by the calmodulin antagonist, calmidazolium. We observed that calcium saline containing A23187 induced the extrusion of tachyzoite conoid. By immunoelectron microscopy, gold particles bound to anti-calmodulin or anti-actin mAb, were found to be localized on the anterior portion of tachyzoites. Remarkably reduced intracellular $Ca^{2+}$ was observed in tachyzoites treated with BAPTA/AM by confocal microscopy. These results suggest that host cell invasion and the intracellular replication of T. gondii tachyzoites are inhibited by the calcium ionophore, A23187, and by the extracellular calcium chelator, EGTA.

• Korean Journal of Veterinary Research
• /
• v.29 no.2
• /
• pp.19-24
• /
• 1989

To elucidate the physiological characteristics of histamine receptor of the isolated renal artery in dog, effects of various receptor blockers and $Ca^{{+}{+}}$ channel blockers on the contractile responses of histamine were investigated in the isolated renal artery of dog. The results were summarized as follows: 1. Histamine caused the contraction in the isolated renal artery of dog, and the contractile responses increased between the concentration of $5{\times}10^{-6}M$ and $10^{-2}M$ in dose-dependent manner. 2. The contractile response induced by histamine ($10^{-3}M$) was not blocked by pretreatment with atropine ($10^{-6}M$), phentolamine ($10^{-6}M$), propranolol ($10^{-6}M$) or cimetidine ($10^{-6}M$), but was completely blocked by pretreatment with pyrilamine ($10^{-6}M$). 3. The contractility induced by histamine ($10^{-3}M$) was decreased in the $Ca^{{+}{+}}$ free medium. 4. The contractile response induced by histamine ($10^{-3}M$) was markedly inhibited by pretreatment with papaverine ($5{\times}10^{-5}M$) or verapamil ($5{\times}10^{-5}M$). 5. After the pre-contraction induced by norepinephrine ($10^{-7}M$) or prostaglandin $F2{\alpha}$ ($5{\times}10^{-6}M$), the contractile response induced by the additional treatment of histamine ($10^{-3}M$) was markedly increased compared with that of histamine ($10^{-3}M$) alone.

• The Korean Journal of Physiology and Pharmacology
• /
• v.2 no.6
• /
• pp.715-724
• /
• 1998

Frequency-force relationships (FFR) were studied in electrically field stimulated rat left atria (LA) by reducing the stimulation frequency from resting 3 Hz to test frequencies (0.1-1 Hz) for 5 minutes. The twitch amplitudes of LA elicited the typical negative staircases with 3-phased changes: the initial rapid increase, the second decrease and the following plateau at test frequencies. Verapamil $(3{\times}10^{-5}\;M)$ pretreatment elicited frequency-dependent suppression of the twitch amplitudes, exaggerating the negative staircase. Monensin pretreatment enhanced not the peak but the plateau amplitudes in a concentration-dependent manner. When the $Na^+-Ca^{2+}$ exchange was blocked by $Na^+\;and\;Ca^{2+}$ depletion in the Krebs Hensleit buffer (0 $Na^+-0\;Ca^{2+}$ KHB), the twitch amplitudes increased in a frequency-dependent manner, changing the negtive staircase into the positve one. Meanwhile, the 0 $Na^+-0\;Ca^{2+}$ KHB applicationinduced enhancement was strongly suppressed by caffeine (5 mM) pretreatment. Only dibucaine among the local anesthetics increased the basal tone during frequency reduciton. There were no differences in $^{45}Ca$ uptakes between 0.3 Hz and 3 Hz stimulation except at 1 min when it was significantly low at 0.3 Hz than 3 Hz, illustrating net $Ca^{2+}$ losses. Monensin pretreatment enhanced the rate of this $Ca^{2+}$ loss. Taken together, it is concluded that $Na^+-Ca^{2+}$ exchange extrudes more SR released $Ca^{2+}$ out of the cell in proportion to the frequency, resulting in the negative rate staircase in the rat LA.

• Journal of Periodontal and Implant Science
• /
• v.26 no.3
• /
• pp.669-679
• /
• 1996

Gingival overgrowth is a well known side effect of several drugs, including nifedipine, phenytoin, cyclosporin, dilitiazem, verapamil. A number of studies have been performed to investigate the mechanism by which nifedipine(a calcium channel blocking agent) affects the gingival tissue. The aim of the present work was to investigate the effect of nifedipine on healthy gingival fibroblasts with special emphasis on determining the changes in cellular proliferation and protein and collagen synthesis. Gingival fibroblasts were obtained from the explants of healthy gingiva of extracted 3rd molars or premolar teeth extracted from the patients for orthodontic treatment. To evaluate the effect of nifedipine on cell proliferation, the cells were seeded at a cell density of $1{\times}10^4$cells/well in 24-well culture plates and treated with 100 and 200ng/ml of nifedipine for 10days. After trypsinization, the cells were counted with a haemocytometer on 1st, 3rd, 5th, 7th and 10th days. Then, MTT assay was carried out. For total protein and percent collagen synthesis, $3{\mu}Ci/ml$ $^3H-proline$ was added to each well for the final 4 hours of the incubation period. The results indicate that nifedipine does not influence cell proliferation in healthy gingival fibroblast in vitro and has a specific effect in reducing total protein and percent collagen synthesis. On the above the findings, exogenous nifedipine does not influence on healthy human gingival fibroblast proliferation and protein and collagen synthesis.

• Korean Journal of Biological Psychiatry
• /
• v.1 no.1
• /
• pp.40-59
• /
• 1994

The introduction of lithium salts for the treatment of mood disorder by Code in 1949 was a major therapeutic breakthrough. Yet it is far from the universal therpeutic agent in the treatment of mood disorders. Indeed, some acutely manic patients do not respond adeqately to lithium and some individuals experience breakthrough affective episodes during lithium maintenance. In the last decode, it has become c1ear that a significant number of patients with more highly recurrent disorders may require alternative or enhanced forms of prophylactic treatment. For these reasons, a variety of other drugs hove been employed for the treatment and prophylaxis of mood disorders. Efforts to develop new pharmacologic strategies for mood disorder hove included a diverse array of medications, ranging from potent benzodiazepines to novel neuroleptics and from anticonvulsants to calcium channel blockers. The anticonvulsants appear particularly useful in cases of dysphoric mania and rapid cycling state, subforms of bipolar disorder that respond quite poorly to conventional treatments. Among all of these new pharmacologic strategy, carbamazepine and sodium valproate have received the broadest clinical applications as maintenance therapies. The data documenting the short-term antimanic effectiveness of the calcium channel blocker verapamil and benzodiazepins such as clonazepam and lorazepam appear also promising. A number of other theoretically interesting, as well as clinically relevant therapies, which are not presently employed routinly, hove also been studied, including 2 blocker clonidine, atypical antipsychotic clozapine, cholinomimetics, 5-HT enhancers, thyroid and magnesium preparations. Now prophylaxis in mood disorder remains a considerable therapeutic challenge. Controlled testing of the prophylactic efficacy of compounds such as carbamazepine, valproic acid, and the calcium channel blockers represent important next step in the clinical trials for mood disorder.

• The Korean Journal of Physiology
• /
• v.28 no.2
• /
• pp.159-167
• /
• 1994

The contraction of rabbit basilar artery was examined as a function of changes in the $Na^+$ electrochemical gradient in order to determine the contribution of $Na^+/Ca^{2+}$ exchange to the modulation of contractility. Ouabain $(10^{-5}\;M)$ or $K^+-free$ Tyrode solution caused an increase in tonic tension even in the presence of a $Ca^{2+}$ channel blocker $(10^{-6}\;M\;verapamil)$ and an ${\alpha}-receptor$ blocker $(10^{-5}\;M\;phentolamine)$. After treatment with ouabain $(10^{-5}\;M)$, contractions were augmented by reduction of external $Na^+$ concentration. The longer the treatment with ouabain $(10^{-5}\;M)$ was, the larger the amplitude of $Na^+-free$ contracture was. $Na^+-free$ contracture wag induced by either substitution of equimolar Tris for $Na^+$ or substitution of equimolar $Li^+\;for\;Na^+$. The competition between $Na^+\;and\;Ca^{2+}$ for the $Na^+/Ca^{2+}$ exchange carrier would exist, because it was observed that contractility was dependent on the $Na^+$ electrochemical gradient or the extracellular $Ca^{2+}$ concentration (2 mM, 4 mM). Ryanodine $(10^{-7}\;M)$, the blocker of intracellular $Ca^{2+}$ release from the sarcoplasmic reticulum, did not suppress the development of $Na^+-free$ contracture. The contractile response to norepinephrine $(10^{-6}\;M)$ was augmented by reducing the extracellular $Na^+$ concentration. The relaxation rate from caffeine-induced contraction was dependent on the extracellular $Na^+$ concentration (0 mM, 140 mM). From the above results, it could be suggested that $Na^+/Ca^{2+}$ exchange can move $Ca^{2+}$ either into or out of rabbit basilar arterial smooth muscle. $Ca^{2+}$ entry or extrusion is dependent upon the $Na^+$ electrochemical gradient. $Na^+/Ca^{2+}$ exchange plays a significant role in the regulation of contractility in rabbit basilar arterial smooth muscle.

• Archives of Plastic Surgery
• /
• v.41 no.6
• /
• pp.620-629
• /
• 2014

Keloid scars are often considered aesthetically unattractive and frustrating problems that occur following injuries. They cause functional and cosmetic deformities, displeasure, itching, pain, and psychological stress and possibly affect joint movement. The combination of these factors ultimately results in a compromised quality of life and diminished functional performance. Various methods have been implemented to improve keloid scars using both surgical and non-surgical approaches. However, it has proven to be a challenge to identify a universal treatment that can deliver optimal results for all types of scars. Through a PubMed search, we explored most of the literature that is available about the intralesional injection treatment of hypertrophic scars and keloids and highlights both current (corticosteroid, 5-fluorouracil, bleomycin, interferon, cryotherapy and verapamil) and future treatments (interleukin-10 and botulinum toxin type A). The reference lists of retrieved articles were also analysed. Information was gathered about the mechanism of each injection treatment, its benefits and associated adverse reactions, and possible strategies to address adverse reactions to provide reliable guidelines for determining the optimal treatment for particular types of keloid scars. This article will benefit practitioners by outlining evidence-based treatment strategies using intralesional injections for patients with hypertrophic scars and keloids.

• Korean Journal of Environmental Biology
• /
• v.18 no.2
• /
• pp.255-262
• /
• 2000

This study was carried out to investigate the physiological changes induced acutely with the low doses of lead acetate in the synaptosomes from the cerebrum and brain stem of the rat. The general uptake patterns of [$^3$H]-serotonin were observed in synaptosomes, as a model of presynaptic nerve terminal, from the cerebrum and brain stem. And the effects of the low doses of lead acetate on the uptake process were investigated id vitro and in vivo. The Km value of the uptake of the [$^3$H]-serotonin by the synaptosomes was 0.5 $\mu$M in the cerebrum and 0.1 $\mu$M in the brain stem. These low values reveal that the synaptosomes from the cerebrum and the brain stem have a high affinity to [$^3$H]-serotonin, especially in brain stem. The uptake of $\mu$M-serotonin was dependant on the sodium and potassium ions. When being treated with ouabain, the $Na^+$ $-K^+$ ATPase inhibitor, the uptake of [$^3$H]-serotonin was reduced. This supports strongly that the uptake of [$^3$H]-serotonin was sensitive to the changes of the concentrations of the sodium and potassium ions. When the calcium channel blocker, verapamil, was treated, the uptake of [$^3$H]-serotonin was changed only in synaptosomes from the brain stem. The uptake of [$^3$H]-serotonin was reduced by the lead treatment in the synaptosomes from the cerebrum and brain stem in vitro and in vivo. [lead acetate, synaptosomes, $^3$H-serotonin, rat]

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1994.04a
• /
• pp.274-274
• /
• 1994

본 연구에서는 토끼신장 근위세뇨관 일차배양세포에서 브라디키닌의 생리작용이 phospholipase D (PLD)에 의해 매개되는지를 살펴 보기위해 PLD 효소반응의 특이한 성질인 transphosphatidylation 반응의 생성물인 phosphatidylethanol (PEth) 의 세포내 양을 측정함으로 PLD 효소의 관련성을 규명할 수 있었다. 시간경과에 따른 phosphatidic acid (PA) 및 diacylglycerol (DAG) 의 생성을 살펴본 결과 PA가 DAG보다 먼저 생성되어 최고치 (30초)에 도달하였고 DAG는 1분이후부터 5분까지 서서히 생성되는 양상을 나타내었다. 또한 0.5에서 5％까지의 에탄올 존재하에 PA 및 PE소 생성량을 비교해본 결과 에탄올량이 증가함에 따라 PA는 감소하는 반민 PEth 의 생성은 계속 증가하였다. 한편 브라디키닌 농도 변화 실험에서는 브라디키닌농도가 증가함에 따라 PA 및 PEth 둘다 생성이 증가되었다. 이러한 결과로부터 토끼신장 근위세뇨관 세포막에 존재하는 브라디키닌수용체는 브라디키닌에 의해 activation 시 PLD를 직접적으로 활성화시켜 그들의 작용을 세포내로 전달한다는 사실을 알 수 있었다. 또한 PLD 효소활성의 activator로 수용체효능 제외에 칼슘이온, protein kinase C (PKC) 등이 몇몇 다른 실험에 의해 밝혀져 있고, G protein 역시 PLD 효소 활성을 조절하는 역할이 있음이 알려졌다. calcium ionophore 및 칼슘채널길항제인 verapamil을 이용한 실험에서 우리는 브라디키닌의 PLD 활성화는 칼슘이온에 의존적인 경로 및 비의존적인 경로가 같이 존재함을 알수 있었다. 또한 브라디키닌의 PLD 활성화기전이 PKC 의존적인지를 살펴보기위해 PKC activator(PMA) 및 inhibitor (staurosporine)를 이용한 실험에서 브라디키닌은 신장세포에서 PKC를 통하여 PLD를 활성화시킴으로 신호전달을 하는 것으로 추측되었다. 마지막으로 가수분해안되는 G protein 유도체인 GTPrS 및 G protein 활성물질 NaF, 백일해독소등을 이용한 실험에서 G protein 의 PLD 조절활성을 확인할 수 있었다.

• Natural Product Sciences
• /
• v.10 no.6
• /
• pp.268-271
• /
• 2004

In order to examine their effects on the P-glycoprotein (P-gp) activity in human breast cancer cells, MCF-7/ADR, one hundred Indonesian plant extracts were screened. Among them, the five chloroform extracts of Calotropis gigantea, Curcuma aeruginosa, Merremia mammosa, Sindora sumatrana, and Zingiber cassumunar, showed the most potent P-gp inhibitory activity. When each of these extracts was treated together with the anticancer agent, daunomycin, they increased the cytotoxic activity of daunomycin up to $IC_{50}$ values of less than $6.62\;{\mu}M$, which is a value with a positive control, verapamil. Also, other 15 plant extracts exhibited significant P-gp inhibitory activity with $IC_{50}$ values between 6.62 and $13.20\;{\mu}M$. These prospective samples will be subjected to further laboratory phytochemical investigation to find active principles.