• The Korean Journal of Physiology and Pharmacology
• /
• v.6 no.4
• /
• pp.173-181
• /
• 2002

The sinoatrial (SA) node is a complex and inhomogeneous tissue in terms of cell morphology and electrical activity. There are two models of the cellular organisation of the sinoatrial node: the gradient and mosaic models. According to the gradient model there is a gradual transition in morphology and electrical properties of SA node cells from the centre to the periphery of the SA node. In the mosaic model, there is a variable mix of atrial and sinoatrial node cells from the centre to the periphery. This review focuses on the cellular organisation of the rabbit sinoatrial node in terms of the expression of connexin (Cx40, Cx43 and Cx45), L-type $Ca^{2+}$ channel and $Na^+-Ca^{2+}$ exchanger proteins. These immunocytochemical data, together with morphological and electrophysiological data, obtained from the intact sinoatrial node and isolated sinoatrial node cells support the gradient model of the cellular organisation of the SA node. The complex organisation of the sinoatrial node is important for the normal functioning of the sinoatrial node: (i) it allows the sinoatrial node to drive the surrounding hyperpolarized atrial muscle without being suppressed by it; (ii) it helps the pacemaker activity of the sinoatrial node continue under a wide range of physiological and pathophysiological conditions; (iii) it helps protect the sinoatrial node from reentrant arrhythmias.

• Asian Pacific Journal of Cancer Prevention
• /
• v.14 no.8
• /
• pp.4897-4902
• /
• 2013

Here we assessed the effectiveness of cervical cancer screening using data from the Hiroshima Prefecture Cancer Registry regarding patient age at the start of screening and differences in screening intervals. A screening model was created to calculate the health status in relation to prognosis following cervical cancer screening and its influence on life expectancy. Epidemiological data on the mortality rate of cervical cancer by age groups and mortality rates from the Hiroshima Prefecture Cancer Registry were used for the model projections. Our results showed that life expectancy when screening rate was 100% compared with 0% was extended by approximately 1 month. Furthermore, when the incidence of cervical cancer was 0% compared with the screening rate was 100%, life expectancy was extended by a maximum of 3 months. Moreover, among individuals affected by cervical c ancer, a difference of 13 years in life expectancy was calculated between screened and unscreened groups.

• IMMUNE NETWORK
• /
• v.11 no.6
• /
• pp.416-419
• /
• 2011

Dextran sodium sulfate (DSS) is a widely used chemical model for inflammatory bowel disease (IBD). It is thought that imbalances in the T helper (Th) cell subsets contribute to IBD. Recent studies suggest that the acute DSS-colitis model is polarized toward a Th1/Th17 profile based on RT-PCR analysis of colonic tissues. In the current study we determined whether colonic Th cells from DSS-colitis mice were skewed toward the Th17 profile. Mice were treated with 5% DSS for 7 days and colonic T cells isolated and examined for production of IFN-${\gamma}$ (Th1 cell), IL-4 (Th2 cell) and IL-17 (Th17 cell) by intracellular flow cytometry. We found that the percentage of colonic Th17 cells were similar to non-treated controls but the percentage of Th1 cells were elevated in DSS-colitis mice. These results suggest that in the acute DSS-colitis model the colonic Th cells exhibit a Th1 profile and not a Th17 profile.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.66 no.3
• /
• pp.581-586
• /
• 2017

The well-known Integral Pulse Frequency Modulation (IPFM) cardiac oscillator has been used to generate the heart beat fluctuations as a representation of the modulatory autonomic nervous activity in terms of sympathetic and parasympathetic state. The IPFM model produces heartbeats by integrating the modulated sinusoid signals and applying the threshold of unity or chaotic threshold levels. This study aims at evaluating the performance of IPFM model by analyzing the influence of the threshold level with comparatively applying preset threshold of unity and Logistic-map and Henon-map chaotic-threshold. Based on our simulated results with interpreting the spectral features of Heart Rate Variability (HRV), we can conclude that the IPFM model with preset threshold level of unity can generate the optimal heartbeat variations int the sense of clinically valid heartbeats.

• Biomedical Science Letters
• /
• v.20 no.4
• /
• pp.227-236
• /
• 2014

Ulcerative colitis (UC) is a serious gastrointestinal tract disease characterized by recurrent chronic inflammation and mucosal damage of the gastrointestinal tract. The conventional therapies of choice are anti-inflammatory agents, steroids and anti-TNF-${\alpha}$ therapy. However, inherent limitations in these therapies have steered many UC patients to supplement existing therapies with alternative medicinal products. In the current study, we tested the efficacy of Gingko bilola extract (EGb 761) in abating colonic inflammation in a DSS-induced murine model of colitis. C57BL/6 mice were administered 2% DSS in the drinking water for 7 days, then regular water for 7 days, and then 2% DSS for an additional 7 days. EGb 761 (1 mg/dose) was oral gavaged daily for the duration of the experiment. At the termination of the experiment, mice treated with EGb+DSS showed higher body weight, lower spleen weight and longer colon length compared to mice treated with DSS alone. HE-stained colon tissues also exhibited less histologic inflammation in mice treated with EGb+DSS mice compared to mice treated with DSS alone. The serum levels inflammatory cytokines, KC and TNF-${\alpha}$, were also decreased in mice treated with EGb+DSS compared to mice treated with DSS alone. Finally, addition of EGb 761 to TNF-${\alpha}$ treated colonic cell line (HT29/c1) decreased secretion of IL-8 in vitro. These results collectively suggest that EGb 761 abates induction of colitis in DSS-induced model of colitis in mice.

• Journal of Biomedical Engineering Research
• /
• v.41 no.5
• /
• pp.195-202
• /
• 2020

Needle detection in ultrasound images is sometimes difficult due to obstruction of fat tissues. Accurate needle detection using continuous ultrasound (CUS) images is a vital stage of treatment planning for tissue biopsy and brachytherapy. The main goal of the study is classified into two categories. First, new detection model, i.e. D-Attention Unet, is developed by combining the context information of 3D medical data and CUS images. Second, the D-Attention Unet model was compared with other models to verify its usefulness for needle detection in continuous ultrasound images. The continuous needle images taken with ultrasonic waves were converted into still images for dataset to evaluate the performance of the D-Attention Unet. The dataset was used for training and testing. Based on the results, the proposed D-Attention Unet model showed the better performance than other 3 models (Unet, D-Unet and Attention Unet), with Dice Similarity Coefficient (DSC), Recall and Precision at 71.9%, 70.6% and 73.7%, respectively. In conclusion, the D-Attention Unet model provides accurate needle detection for US-guided biopsy or brachytherapy, facilitating the clinical workflow. Especially, this kind of research is enthusiastically being performed on how to add image processing techniques to learning techniques. Thus, the proposed method is applied in this manner, it will be more effective technique than before.

• The Journal of Advanced Prosthodontics
• /
• v.11 no.3
• /
• pp.169-178
• /
• 2019

PURPOSE. While dental implants have displayed high success rates, poor mechanical fixation is a common complication, and their biomechanical response to occlusal loading remains poorly understood. This study aimed to develop and validate a computational model of a natural first premolar and a dental implant with matching crown morphology, and quantify their mechanical response to loading at the occlusal surface. MATERIALS AND METHODS. A finite-element model of the stomatognathic system comprising the mandible, first premolar and periodontal ligament (PDL) was developed based on a natural human tooth, and a model of a dental implant of identical occlusal geometry was also created. Occlusal loading was simulated using point forces applied at seven landmarks on each crown. Model predictions were validated using strain gauge measurements acquired during loading of matched physical models of the tooth and implant assemblies. RESULTS. For the natural tooth, the maximum vonMises stress (6.4 MPa) and maximal principal strains at the mandible ($1.8m{\varepsilon}$, $-1.7m{\varepsilon}$) were lower than those observed at the prosthetic tooth (12.5 MPa, $3.2m{\varepsilon}$, and $-4.4m{\varepsilon}$, respectively). As occlusal load was applied more bucally relative to the tooth central axis, stress and strain magnitudes increased. CONCLUSION. Occlusal loading of the natural tooth results in lower stress-strain magnitudes in the underlying alveolar bone than those associated with a dental implant of matched occlusal anatomy. The PDL may function to mitigate axial and bending stress intensities resulting from off-centered occlusal loads. The findings may be useful in dental implant design, restoration material selection, and surgical planning.

• Journal of the Optical Society of Korea
• /
• v.18 no.1
• /
• pp.55-59
• /
• 2014

Sarcopenia, or reduced muscle mass and volume, is due to various factors such as senile change, neuronal degeneration, drug, malignancy, and sepsis. Sarcopenia with the aging process has been evidenced by the decline in muscle mass by 0.5 to 1% per year with 3-5% reduction in muscle strength for 10 years between the ages of 40 and 50, and a 1-2% of decline of mass every year in people aged 60-70. Therefore, early diagnosis and understanding the mechanism of sarcopenia are crucial in the prevention of muscle loss. However, it is still difficult to image changes of muscle microstructure due to a lack of techniques. In this study, we developed an animal model using denervated rats to induce a rapid atrophy in the tibialis anterior (TA) and imaged its structural changes using optical coherence tomography (OCT) along with histologic and ultrasound analyses. Ultrasound showed changes of overall muscle size. Histology revealed that the atrophic TA muscle displayed an increased size variability of muscle fiber and inflammatory changes. Three dimensional OCT imaged the changes of perimysial grid and muscle fiber structure in real time without sacrifice. These observed advantages of multimodal imaging using OCT and ultrasound would provide clinical benefits in the diagnosis of sarcopenia.

• Imaging Science in Dentistry
• /
• v.39 no.1
• /
• pp.35-39
• /
• 2009

Purpose: The purpose of the experiment was to evaluating the diagnostic ability of dental caries detection using digital subtraction in the artificial caries activity model. Materials and Methods: Digital radiographies of five teeth with 8 proximal surfaces were obtained by CCD sensor (Kodak RVG 6100 using a size #2). The digital radiographic images and subtraction images from artificial proximal caries were examined and interpreted. In this study, we proposed novel caries detection method which could diagnose the dental proximal caries from single digital radiographic image. Results: In artificial caries activity model, the range of lesional depth was $572-1,374{\mu}m$ and the range of lesional area was $36.95-138.52mm^2$. The lesional depth and the area were significantly increased with demineralization time (p<0.001). Furthermore, the proximal caries detection using digital subtraction radiography showed high detection rate compared to the proximal caries examination using simple digital radiograph. Conclusion: The results demonstrated that the digital subtraction radiography from single radiographic image of artificial caries was highly efficient in the detection of dental caries compared to the data from simple digital radiograph.

• Proceedings of the KIEE Conference
• /
• 2008.10a
• /
• pp.184-184
• /
• 2008

This paper presents the measurement of the mechanical property of PDMS (Polydimethylsiloxane) elastomer depending on volumetric mixing ratios of base polymer and curing agent and their hyperelastic material models.