• The Korean Journal of Physiology and Pharmacology
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• v.27 no.6
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• pp.541-553
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• 2023

Retinal prostheses have shown some clinical success in restoring vision in patients with retinitis pigmentosa. However, the post-implantation visual acuity does not exceed that of legal blindness. The reason for the poor visual acuity might be that (1) degenerate retinal ganglion cells (RGCs) are less responsive to electrical stimulation than normal RGCs, and (2) electrically-evoked RGC spikes show a more widespread not focal response. The single-biphasic pulse electrical stimulation, commonly used in artificial vision, has limitations in addressing these issues. In this study, we propose the benefit of multiple consecutive-biphasic pulse stimulation. We used C57BL/6J mice and C3H/HeJ (rd1) mice for the normal retina and retinal degeneration model. An 8 × 8 multi-electrode array was used to record electrically-evoked RGC spikes. We compared RGC responses when increasing the amplitude of a single biphasic pulse versus increasing the number of consecutive biphasic pulses at the same stimulus charge. Increasing the amplitude of a single biphasic pulse induced more RGC spike firing while the spatial resolution of RGC populations decreased. For multiple consecutive-biphasic pulse stimulation, RGC firing increased as the number of pulses increased, and the spatial resolution of RGC populations was well preserved even up to 5 pulses. Multiple consecutive-biphasic pulse stimulation using two or three pulses in degenerate retinas induced as much RGC spike firing as in normal retinas. These findings suggest that the newly proposed multiple consecutive-biphasic pulse stimulation can improve the visual acuity in prosthesis-implanted patients.

• Journal of Plant Biotechnology
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• v.38 no.1
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• pp.22-29
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• 2011

Although reactive oxygen species (ROS) are inevitable by-products of many redox reactions in eukaryotic cells, they play a crucial role as signaling molecules in many cellular processes for development and defense response to abiotic stresses. The biphasic ROS production which was peaked twice in a first transient phase and a second massive phase was occurred after treatment of abiotic stress such as oxidative stress, high salinity. This biphasic generation of ROS was followed by the biphasic production of stress hormone, ethylene. The mechanism of interactions between ROS and ethylene biosynthesis is studied in tobacco (Nicotiana tabaccum L.) plants under the abiotic stresses. The stress-induced ethylene production was significantly inhibited in RbohD-AS and RbohF-AS, in which antisense expression of NADPH oxidase genes was performed. The accumulation of ROS, which was determined by DAB and DCFH-DA staining, was significantly decreased after abiotic stresses in transgenic plants. The suppression of signaling with ethylene and ROS induced more tolerance in response to abiotic stress. The transgenic plants were more tolerant in MS medium supplemented with salinity stress in contrast with wild-type. Stress-induced cell damage determined by DNA fragmentation was decreased at phase II in those transgenic plants. Therefore, the first burst of ROS is more responsible for making a role as a signaling molecule during stress-induced response. These results suggested that ethylene and ROS act in a positive feedback cycle that results in mutual enhancement of ethylene and ROS production during stress-induced cell death.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.293-296
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• 2002

Hyperosmotic pressure increased specific antibody productivity ($q_{Ab}$) of recombinant CHO cells (SH2-0.32) while it depressed cell growth. Thus, the use of hyperosmolar medium did not increase the maximum antibody concentration substantially. To overcome this drawback, the feasibility of biphasic culture strategy was investigated. In the biphasic culture, cells were first cultivated in the standard medium with physiological osmolality(294 mOsm/kg) for cell growth. When cells reached the late exponential phase of growth, the spent standard medium was replaced with the fresh hyperosmolar medium (522 mOsm/kg) for antibody production. The ($q_{Ab}$) in growth phase with the standard medium was 2.1 ${\mu}g/10^6cell/day$ while the ($q_{Ab}$) in antibody production phase with the hyperosmolar medium (522 mOsm/kg) was 11.1 ${\mu}g/10^6cell/day$. Northern blot analysis showed a positive relationship between the relative contenet of Ig mRNA and ($q_{Ab}$), indicating that transcriptional regulation was involved in the response of rCHO cells to hyperosmotic pressure. Due to the enhanced ($q_{Ab}$) and increased cell concentration in biphasic culture, the maximum antibody concentration obtained in biphasic culture with 522 mOsm/kg medium exchange was 161% higher than that obtained in batch culture with the standard medium. Taken together, simple biphasic culture strategy based on hyperosmotic culture for improved foreign protein production from rCHO cells is effective in improving antibody production of rCHO cells.

• Korean Journal of Veterinary Research
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• v.61 no.2
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• pp.14.1-14.7
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• 2021

Biosilica is a silica-based substance derived from the cell walls (frustules) of diatoms. Recently, research into biosilica's biological functions is underway, but little has been reported on the effects of biosilica on immune cells. In this study, we investigated the effect of ionized biosilica water (iBW) on dendritic cells (DCs), which play crucial roles as antigen (Ag)-presenting cells. Treatment with iBW increased the expression of immune response-related markers, closely connected to the maturation of DCs, and the production of tumor necrosis factor-alpha. In addition, iBW-treated DCs (iBW-DCs) had a lower uptake of fluorescein isothiocyanate-dextran than that of control DCs. Mixed leukocyte response analysis used for measuring the Ag-presenting capability of DCs, showed iBW-DCs had a higher capability than that of control DCs. Interestingly, DCs treated with lipopolysaccharide (LPS) and iBW had a lower level of Ag-presenting capability than that of LPS-treated DCs. Taken together, the results indicate that iBW alone can mature DCs, but it decreases the Ag-presenting capability of DCs in the presence of LPS, a representative agent of inflammation. This study may provide valuable information regarding the effect of iBW on immune cells. Further research is needed to investigate how iBW induces the observed biphasic immunomodulatory activity.

• The Korean Journal of Food And Nutrition
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• v.10 no.2
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• pp.151-159
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• 1997

In order to compare and examine the general characteristics of myofibrillar proteins which is an important protein source as a food resource and relates directly with muscle contraction, we have extracted the myofibrillar proteins from squid and clam. The ionic strength of myofibrillar proteins connected with Ca-ATPase activity, Mg-ATPase activity and EDTA-ATPase activity showed distinct differences between squid and clam. In the activity-pH curve, actomyosin of the clam had a weak biphasic response. In the low concentration of dioxane, myofibrillar proteins of the squid showed a sudden decrease in activity but myofibrillar proteins of the clam showed in increase in activity. Ethanol and metanol in low concentration caused myosin and HMM from the squid and clam to increase their activities. If we cause modification by NEM, under 10-6M concentration, the activity was increased but above 10-5M concentration, there was a sudden decrease in activity.

• Journal of the Korean Society of Physical Medicine
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• v.6 no.2
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• pp.207-213
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• 2011

Purpose: The purpose of this study was to determine the preventive effect of joint mobilization on biphasic pain response induced formalin test. Methods: Sprague-dawley rats(n=30) were ramdomly divided into the control group without intervention, sham control group with application of hand contact without mobilization, joint mobilization group with application of hand contact with mobilization. Joint mobilization of knee procedure involved an grade III extension mobilization basically with anterior-posterior gliding of the tibia on the femur. Formalin injection caused biphasic pain response which is lated for 60 minute. The first phase result from primary afferent sensory fiber, wheareas the second phase has been proposed to central sensitization in the central nervous system. Behavioral analysis was performed by digital camera after 5% formalin subcutaneous injection into the dorsal foot. Results: Pain response of joint mobilization group show significant lower than control gorup and sham control group. Conclusion: This result suggest that pre-application of joint mobilization may be effective intervention to prevent the formalin induced pain.

• The Korean Journal of Physiology
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• v.29 no.2
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• pp.203-216
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• 1995

The effects of ${\alpha}_1-adrenergic$ receptor stimulation on membrane potential, intracellular $Na^+$ activity, and twitch force were investigated in ventricular muscles from guinea-pig hearts. Action potentials, intracellular $Na^+$ activity, and twitch force of ventricular papillary muscles were measured simultaneously under various experimental conditions. Stimulation of the ${\alpha}_1-adrenergic$ receptor by phenylephrine produced variable changes in action potential duration, a slight hyperpolarization of the diastolic membrane potential, a decrease in intracellular $Na^+$ activity, and a biphasic inotropic response in which a transient negative inotropic response was followed by a sustained positive inotropic response. These changes were blocked by prazosin, an antagonist of the ${\alpha}_1-adrenergic$ receptor, but not by atenolol, an antagonist of the ${\beta}-adrenergic$ receptor. This indicates that the changes in membrane potential, intracellular $Na^+$ activity, and twitch force are mediated by stimulation of the ${\alpha}_1-adrenergic$ receptor, but not by stimulation of ${\beta}-adrenergic$ receptor. The decrease in intracellular $Na^+$ activity was not observed in quiescent muscles, depending on the rate of the action pontentials in beating muscles. The intracellular $Na^+$ activity decrease was substantially inhibited by tetrodotoxin. However, the decrease in intracellular $Na^+$ activity was not affected by an inhibition of the $Na^+-K^+$ pump. Therefore, the decrease in intracellular $Na^+$ activity mediated by the ${\alpha}_1-adrenergic$ receptor appears to be due to a reduction of $Na^+$ influx during the action potential, perhaps through tetrodotoxin sensitive $Na^+$ channels. Our study also revealed that the decrease in intracellular $Na^+$ activity might be related to the transient negative inotropic response. The intracellular $Na^+$ activity decrease could lower intracellular $Ca^{2+}$ through the $Na^+-Ca^{2+}$ exchanger and thereby produce a decline in twitch force.

• The Korean Journal of Physiology
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• v.25 no.2
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• pp.201-209
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• 1991

The rostral ventrolateral medulla (RVLM) has been established recently as a sympathoexcitatory area. The present study was conducted to investigate whether the somatosympathetic pressor and/or depressor responses are mediated through RVLM in cats anesthetized with ${\alpha}-chloralose$. An occipital craniectomy was performed and ventrolateral medulla were stimulated either electrically or chemically to evoke changes in arterial blood pressure. And then the effect of lesions in the ventrolateral medulla on the changes in blood pressure elicited by the peripheral nerve stimulation was observed. Followings are the results obtained: 1) Pressor areas were found in the ventrolateral medulla, lateral reticular nucleus and rostral dorsal area. 2) Depressor areas were found mainly in the ventrolateral medulla rostral to the pressor areas. 3) Some areas showed biphasic responses: a depressor response to lower frequency and a pressor response to higher frequency stimulation. 4) After electrical lesion in pressor area in RVLM, the somatosympathetic pressor response was abolished or depressed markedly. The somatosympathetic depressor response, however, remained after the lesion. 5) Electrical lesion in the depressor area abolished somatosympathetic depressor response. From the above results it is concluded that somatosympathetic pressor response is mediated through RVLM, while somatosympathetic depressor response is not mediated through RVLM.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1997.04a
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• pp.108-108
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• 1997

The effects of nalbuphine.HCI on the spontaneous locomotor activity and primary humoral immune response were investigated in ICR mice. Nalbuphine was intraperitoneally administered with the dose of 130, 260, 360 mg/kg in mice. The locomotor activity such as distance traveled was observed for 90min at 10min intervals. Nalbuphine showed the biphasic dose-response relationship on the spontaneous locomotor activity. IgM plaque forming cells(PFC) in splenocytes and IgM level in antiserum were significantly decreased depending on the dose of nalbuphine when nalbuphine was administered after the immunization, but slightly increased only at the low dose in the case of nabuphine administration after the immunization(SRBC).

• Archives of Pharmacal Research
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• v.21 no.4
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• pp.370-373
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• 1998

Ten substituted phenacyl derivatives of 4-hydroxypiperidine were synthesized and studied for their effects on the mean arterial blood pressure (MABP) in normotensive anaesthetized rats and smooth muscles contractions of isolated rabbit jejunum. Two derivatives caused fall in blood pressure at the dose of 10-20 mg/kg and one rise in blood pressure at the dose of 20 mg/kg. Two compounds exhibited biphasic response (hypotensive followed by hypertensive) and one gave triphasic response at 10 mg/kg dose. Rest of four derivatives were found devoid of any effect on mean arterial blood pressure up to the dose of 30 mg/kg. All the derivatives except two caused relaxant effect on the spontaneous contraction of rabbit jejunum at the dose range of 0.1 -2 mg/kg.