• The Korean Journal of Physiology and Pharmacology
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• v.14 no.2
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• pp.113-118
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• 2010

The sensory system is developed and optimized by experiences given in the early phase of life in association with other regions of the nervous system. To date, many studies have revealed that deprivation of specific sensory experiences can modify the structure and function of the central nervous system; however, the effects of sensory overload remains unclear. Here we studied the effect of overloading the taste sense in the early period of life on the synaptic plasticity of rat hippocampus and somatosensory cortex. We prepared male and female Sprague Dawley rats with ad libitum access to a 0.1% saccharin solution for 2 hrs per day for three weeks after weaning on postnatal day 22. Saccharin consumption was slightly increased in males compared with females; however, saccharin intake did not affect chow intake or weight gain either in male or in female rats. We examined the effect of saccharin-intake on long term potentiation (LTP) formation in hippocampal Schaffer collateral pathway and somatosensory cortex layer IV - II/III pathways in the 6-week old saccharin-fed rats. There was no significant difference in LTP formation in the hippocampus between the control group and saccharin-treated group in both male and female rats. Also in the somatosensory cortex, we did not see a significant difference in LTP among the groups. Therefore, we conclude that saccharin-intake during 3~6 weeks may not affect the development of physiological function of the cortical and hippocampal synapses in rats.

• The Korean Journal of Physiology
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• v.29 no.2
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• pp.279-289
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• 1995

This study was designed 1) to develop a hypertensive animal model in which the blood pressures (BPs) of symmetric regions (right and left upper extremities) are significantly different and 2) to test the effect of BP per se on the contractility and endothelium-dependent relaxation of vascular smooth muscle. Rabbits were anesthetized with sodium pentobarbital and ventilated with room air via animal respirator. The transverse aorta was exposed through the left second intercostal space and the lumen of the aorta was narrowed partially by ligation using 3-0 silk and a probe at a point between the origins of the brachiocephalic trunk and the left subclavian artery. Four to eight weeks postoperatively, BPs were measured in the carotid artery as the high BP area (proximal to coactation site) and in the femoral artery as the low BP area (distal to coarctation site). In the animal model, pressure-overload hypertension was developed and the BP of the right subclavian artery was higher than that of the left subclavian artery. The concentrations of circulating epinephrine, norepinephrine, angiotensin I, and angiotensin II were measured. The right and left subclavian arteries and their branches were used for isometric tension recording in organ baths and their responsiveness to phenylephrine, serotonin, acetylcholine, and sodium nitroprusside were examined. The BPs of carotid and femoral artery in control animals were $116{\pm} 12/75{\pm}9\;mmHg (mean ${\pm}SEM$) and $130{\pm}16/68{\pm}9\;mmHg$ respectively, while those of carotid and femoral artery in the hypetensive animals were $172{\pm}6/111{\pm}10\;mmHg$ and 136{\pm} 4/100 {\pm}9\;mmHg$ respectively. There were no significant differences in the concentrations of circulating epinephrine, norepinephrine, angiotensin I, and angiotensin II between controls and the animal models. No significant differences were found in the vascular sensitivities to phenylephrine and serotonin between the high pressure-exposed vessels and the low pressure-exposed vessels. However, the endothelium-dependent relaxation to acetylcholine and nitroprusside-induced relaxation showed significant differences between the high pressure-exposed and the low pressure-exposed subclavian arteries. From the above results, we suggest that the contractility of vascular smooth muscle is unchanged by the elevated pressure per se. However, the endothelium-dependent relaxation to acetylcholine and the nitroprusside-induced relaxation are attenuated by pressure.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.4
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• pp.352-360
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• 2017

Objectives: This study aimed to determine the effects on musculoskeletal symptoms of both social demographic features and detailed characteristics of each task category of care workers who offer visiting home-help services. And to establish the measures that can reduce musculoskeletal symptoms among care workers. Methods: This study was conducted among 192 care workers from welfare centers C and K located in city P. After participants completed the task burden checklist regarding the scale of musculoskeletal symptoms and the details of their duties, the data collected were analyzed using the SPSS 21.0 program. Results: According to the degree of observable musculoskeletal symptoms in care workers, the highest figures were observed for back and shoulder pain. Based on the results of assessing the effect of detailed task category characteristics on musculoskeletal symptoms, "helping patients eat, helping patients move, helping patients bath, and changing body positions" were found to have an effect from the physical care category, "providing physical therapy assistance, treating bedsores" from the health care category, and "cleaning and doing laundry" from the facility management category. Conclusions: Due to the high proportion of patients requiring burdensome physical labor from care workers such as moving patients who have trouble doing so on their own, helping them change positions, and so on, it is highly likely that pain will occur in the low back, which carries most of the physical weight. So, education on human epidemiological positions that can reduce overload on areas prone to pain such as the low back and shoulders is essential. Proper equipment and personnel support must be provided for dangerous tasks. Further, multidimensional social support is required consistently.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 2003.10a
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• pp.34-63
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• 2003

Occupational and environmental exposure to manganese continue to represent a realistic public health problem in both developed and developing countries. Increased utility of MMT as a replacement for lead in gasoline creates a new source of environmental exposure to manganese. It is, therefore, imperative that further attention be directed at molecular neurotoxicology of manganese. A Need for a more complete understanding of manganese functions both in health and disease, and for a better defined role of manganese in iron metabolism is well substantiated. The in-depth studies in this area should provide novel information on the potential public health risk associated with manganese exposure. It will also explore novel mechanism(s) of manganese-induced neurotoxicity from the angle of Mn-Fe interaction at both systemic and cellular levels. More importantly, the result of these studies will offer clues to the etiology of IPD and its associated abnormal iron and energy metabolism. To achieve these goals, however, a number of outstanding questions remain to be resolved. First, one must understand what species of manganese in the biological matrices plays critical role in the induction of neurotoxicity, Mn(II) or Mn(III)? In our own studies with aconitase, Cpx-I, and Cpx-II, manganese was added to the buffers as the divalent salt, i.e., $MnCl_2$. While it is quite reasonable to suggest that the effect on aconitase and/or Cpx-I activites was associated with the divalent species of manganese, the experimental design does not preclude the possibility that a manganese species of higher oxidation state, such as Mn(III), is required for the induction of these effects. The ionic radius of Mn(III) is 65 ppm, which is similar to the ionic size to Fe(III) (65 ppm at the high spin state) in aconitase (Nieboer and Fletcher, 1996; Sneed et al., 1953). Thus it is plausible that the higher oxidation state of manganese optimally fits into the geometric space of aconitase, serving as the active species in this enzymatic reaction. In the current literature, most of the studies on manganese toxicity have used Mn(II) as $MnCl_2$ rather than Mn(III). The obvious advantage of Mn(II) is its good water solubility, which allows effortless preparation in either in vivo or in vitro investigation, whereas almost all of the Mn(III) salt products on the comparison between two valent manganese species nearly infeasible. Thus a more intimate collaboration with physiochemists to develop a better way to study Mn(III) species in biological matrices is pressingly needed. Second, In spite of the special affinity of manganese for mitochondria and its similar chemical properties to iron, there is a sound reason to postulate that manganese may act as an iron surrogate in certain iron-requiring enzymes. It is, therefore, imperative to design the physiochemical studies to determine whether manganese can indeed exchange with iron in proteins, and to understand how manganese interacts with tertiary structure of proteins. The studies on binding properties (such as affinity constant, dissociation parameter, etc.) of manganese and iron to key enzymes associated with iron and energy regulation would add additional information to our knowledge of Mn-Fe neurotoxicity. Third, manganese exposure, either in vivo or in vitro, promotes cellular overload of iron. It is still unclear, however, how exactly manganese interacts with cellular iron regulatory processes and what is the mechanism underlying this cellular iron overload. As discussed above, the binding of IRP-I to TfR mRNA leads to the expression of TfR, thereby increasing cellular iron uptake. The sequence encoding TfR mRNA, in particular IRE fragments, has been well-documented in literature. It is therefore possible to use molecular technique to elaborate whether manganese cytotoxicity influences the mRNA expression of iron regulatory proteins and how manganese exposure alters the binding activity of IPRs to TfR mRNA. Finally, the current manganese investigation has largely focused on the issues ranging from disposition/toxicity study to the characterization of clinical symptoms. Much less has been done regarding the risk assessment of environmenta/occupational exposure. One of the unsolved, pressing puzzles is the lack of reliable biomarker(s) for manganese-induced neurologic lesions in long-term, low-level exposure situation. Lack of such a diagnostic means renders it impossible to assess the human health risk and long-term social impact associated with potentially elevated manganese in environment. The biochemical interaction between manganese and iron, particularly the ensuing subtle changes of certain relevant proteins, provides the opportunity to identify and develop such a specific biomarker for manganese-induced neuronal damage. By learning the molecular mechanism of cytotoxicity, one will be able to find a better way for prediction and treatment of manganese-initiated neurodegenerative diseases.

• Tuberculosis and Respiratory Diseases
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• v.44 no.1
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• pp.183-190
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• 1997

Tocolytics are agents widely used in the treatment of premature labor to inhibit uterine contractions. Ritodrine is most commonly used tocolytic agent and acts by increasing intracellular cyclic adenosine monophosphate, which decreases the activity of myosin light-chain kinase, the rate-limiting enzyme in the signal network leading to contraction. Physiologic effects associated with the use of ritodrine are due to their effect on bera-l as well as beta-2 receptors. Some of maternal complications of therapy are rachycardia, hyperglycemia, hypokalemia, lactic acidosis, myocardial ischemia, and pulmonary edema. Tocolytics induced pulmonary edema is a serious complication that can lead to marternal death, although infrequent, The incidence varies from 0.5% to 5% of those receiving these agents. Predisposing factors include the concommitant use of corticosteroid, twin gestation, fluid overload (particularly with saline), and anemia. Several mechanisms have been postulated, but the pathogenesis is uncertain. It is suggested that both types of mechanism, hydrostatic and permeability induced, might be involved. The association of tocolytic therapy with pulmonary edema appears to be unique to the pregnant state, because this complication has never been reported in asthmatic patients exposed to high dosages. We report a case of tocolytic induced pulmonary edema developed in 24 hours after delivery.

• Information Systems Review
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• v.17 no.2
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• pp.219-238
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• 2015

As Internet and IT have been developed, people have been exposed to large amounts of information. So, many online information providers recommend relevant information to users to relieve an information overload. However, information recommendation which is based on the taste and preference of a user can lead to a problem of unbalanced information consumption. Prior research about online information has not investigated the side-effect of a recommendation function. This research suggests IT solutions for alleviating unbalanced information consumption behavior. Based on adaptation level theory and expectancy theory, we proposed self-reference point diagnosticity interface and social-reference point diagnosticity interface to help people to consume information following their own information consuming goal. We hypothesized positive impacts of these two interfaces on the self-awareness about information consuming pattern. And we predicted that self-awareness has a positive impact on the motivation and actual behavior to conform the ideal information consuming pattern which the user sets. Laboratory experiment was executed as a research method. As a result, the self-reference diagnosticity interface leaded to higher self-awareness and mitigated the unbalanced information consumption. But, the social-reference diagnosticity interface and the motivation to improve the information consuming behavior had no significant results. Academic and practical implications are discussed.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.1-16
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• 2002

The purposes of this study were to investigate the effects of strength training on the change of ground reaction force for the children with trisomy 21 Down syndrome. The subjects of this study were consisted of eight elementary school students with Down syndrome who participated in the strength training. The strength training was administered by six items such as squat, leg curl, leg extension, toe raise, sit-ups, and hyperextension. For strengthening muscle, each group also was treated by walking for 8 weeks, three times a week, 10-15RM, 3sets, which was based on the principle of progressive overload. For inquiring the effect of strength training, the ground reaction force variables were measured in two phases : before-training and 8 week-after training. The gait of each subject was acquisition using 2 AMTI force platforms set at 100 frequency. The results of this study were as follows: The pattern of vertical, antero-posterior and medio-lateral forces, trajectory of net COP and the timing ratio of reaching the each events were shown variously. So, it is not easy to explain these variables clearly. As the result of strength training, these variables were changed. However, the results of within subjects differ greatly, there was no difference statistically.

• Journal of Intelligence and Information Systems
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• v.13 no.3
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• pp.119-140
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• 2007

Recommender systems enable a user to decide which information is interesting and valuable in our world of information overload. As the recent studies of distributed computing environment have been progressing actively, recommender systems, most of which were centralized, have changed toward a peer-to-peer approach. Collaborative Filtering (CF), one of the most successful technologies in recommender systems, presents several limitations, namely sparsity, scalability, cold start, and the shilling problem, in spite of its popularity. The move from centralized systems to distributed approaches can partially improve the issues; distrust of recommendation and abuses of personal information. However, distributed systems can be vulnerable to attackers, who may inject biased profiles to force systems to adapt their objectives. In this paper, we consider both effective CF in P2P environment in order to improve overall performance of system and efficient solution of the problems related to abuses of personal data and attacks of malicious users. To deal with these issues, we propose a multi-agent framework for a distributed CF focusing on the trust relationships between individuals, i.e. web of trust. We employ an agent-based approach to improve the efficiency of distributed computing and propagate trust information among users with effect. The experimental evaluation shows that the proposed method brings significant improvement in terms of the distributed computing of similarity model building and the robustness of system against malicious attacks. Finally, we are planning to study trust propagation mechanisms by taking trust decay problem into consideration.

• Journal of Korean Public Health Nursing
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• v.12 no.1
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• pp.55-74
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• 1998

In the past most major accidents resulted in death, but today there is a dramatic increase in the number of people who survive such accidents but who are left with permanent injury. Particularly, children who are inquisitive about their surroundings but immature in their ability to assess danger, are more vulnerable to accidents and their causes as well as to determine attitudes towards prevention. The main objective of the study was to assess the effectiveness of using an accident prevention manual for accident for accident prevention education. The study was a quasi-experimental study using a questionnaire format. The subjects of the study were 393 mothers of children attending six day care centers in Seoul. Data collection was done between May 1 and June 15, 1997. The tools used for the study were a questionnaire developed the researchers and a manual for accident prevention. The collected data were analyzed using SPSS. The results of the study are as follows: 1. Types of accidents included stabbing, bums, falls from heights, choking, falls on slippery surfaces, traffic accidents, drowning, poisoning, and electrical shock in that order of frequency. 2. The main causes of accidents in children were from cosmetics and household medications. 3. The most frequent locations of accidents in the home were the bathroom, kitchen, and stairways in that order. 4. For $90.4\%$ of children safety seats were not used when the ridding in a car. 5. In examining the parents' accident prevention practices, it was found that many parents used only . one electrical outlet for many appliances, tending to overload the electricity lines and that they were not practically concerned bout the flammability of children's pajamas, indicating a less than positive attitude towards fire prevention. 6. The parents had not provided their children with any instruction on accident prevention or on what to do after an accident had occurred. 7. After the use of pamphlet in an accident prevention education program, it was found that there was a statistically significant difference in the degree to which children carried out safety measures (t=14.96, p=.000) and in their safety habits (t=-1.67, p<.1) indicating an effectiveness in this method of education. The results of this study showed that there are many things in a child's environment that can cause accidents and that the possibility of an accident occurring is high. So nurses looking after children should be aware of the need for safety education to prevent accidents in the home and plan to provide appropriate educational material to help parents with this education.

• The KIPS Transactions:PartA
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• v.13A no.1 s.98
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• pp.45-52
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• 2006

To perform on-line maintenance for Distributed Information System, it is indispensable to disseminate files to participant nodes in the network. When users' requests for file deployment occur simultaneously in a short period a deployment server falls into overload phase, which is often called Flash Crowds. h common solution to avoid Flash Crowds is to increase hardware capacity. In this paper, we propose a software solution based on P2P, which does not cost any additional expense. In the proposed solution, nodes in the network are grouped into subnetworks one of which is composed of only neighboring nodes. In each subnetwork, copies of deployment files can be transferred to each other. Consequently, it brings about the effect of load balancing in deployment server. To raise the effectiveness, target files for deployment are packed into one package. Before being transferred, each package is divided into multiple equal-sized segments. A deployment server in a normal phase transmits a package requested from nodes in segment units. However a deployment server is overloaded, if segments already exist in the subnetwork participant nodes in the subnetwork receive necessary segments from neighboring nodes. In this paper, we propose data structures and algorithm for this approach and show performance improvement through simulation.