Showing papers by "Gifu University of Medical Science published in 2009"
TL;DR: Co-immunoprecipitation demonstrated that Mfa2 and Mfa1 are associated with each other in whole P. gingivalis cells, and immunogold microscopy confirmed that MFA2 was located on the cell surface and likely associated with Mfa 1 fimbriae.
Abstract: Porphyromonas gingivalis, a causative agent of periodontitis, has at least two types of thin, single-stranded fimbriae, termed FimA and Mfa1 (according to the names of major subunits), which can be discriminated by filament length and by the size of their major fimbrilin subunits. FimA fimbriae are long filaments that are easily detached from cells, whereas Mfa1 fimbriae are short filaments that are tightly bound to cells. However, a P. gingivalis ATCC 33277-derived mutant deficient in mfa2, a gene downstream of mfa1, produced long filaments (10 times longer than those of the parent), easily detached from the cell surface, similar to FimA fimbriae. Longer Mfa1 fimbriae contributed to stronger autoaggregation of bacterial cells. Complementation of the mutant with the wild-type mfa2 allele in trans restored the parental phenotype. Mfa2 is present in the outer membrane of P. gingivalis, but does not co-purify with the Mfa1 fimbriae. However, co-immunoprecipitation demonstrated that Mfa2 and Mfa1 are associated with each other in whole P. gingivalis cells. Furthermore, immunogold microscopy, including double labelling, confirmed that Mfa2 was located on the cell surface and likely associated with Mfa1 fimbriae. Mfa2 may therefore play a role as an anchor for the Mfa1 fimbriae and also as a regulator of Mfa1 filament length. Two additional downstream genes (pgn0289 and pgn0290) are co-transcribed with mfa1 (pgn0287) and mfa2 (pgn0288), and proteins derived from pgn0289, pgn0290 and pgn0291 appear to be accessory fimbrial components.
48 citations
TL;DR: The spatial uncertainty will be less than 2 mm when suitable treatment planning, optimal patient setup, and daily quality assurance for the Novalis system are achieved in the routine workload.
Abstract: Purpose: The purpose of this study was to evaluate the accuracy of a new version of the ExacTrac X-ray (ETX) systemwithstatisticalanalysisretrospectivelyinordertodeterminethetoleranceofsystematiccomponentsofspatial uncertainties with the Novalis system. Methods and Materials: Three factors of geometrical accuracy related to the ETX system were evaluated by phantom studies. First, location dependency of the detection ability of the infrared system was evaluated. Second, accuracy of the automated calculation by the image fusion algorithm in the patient registration software was evaluated. Third, deviation of the coordinate scale between the ETX isocenter and the mechanical isocenter was evaluated. From the values of these examinations and clinical experiences, the total spatial uncertainty with the Novalis system was evaluated. Results: As to the location dependency of the detection ability of the infrared system, the detection errors between the actual position and the detected position were 1% in translation shift and 0.1 � in rotational angle, respectively. As to the accuracyof patient verification software, the repeatability and the coincidence of the calculationvalue by image fusion were good when the contrast of the X-ray image was high. The deviation of coordinates between the ETX isocenter and the mechanical isocenter was 0.313 ± 0.024 mm, in a suitable procedure. Conclusions: The spatial uncertainty will be less than 2 mm when suitable treatment planning, optimal patient setup, and daily quality assurance for the Novalis system are achieved in the routine workload. 2009 Elsevier Inc. Spatial uncertainty, Image-guided radiotherapy, Geometrical accuracy, Patient setup, Stereotactic radiotherapy.
45 citations
TL;DR: Results indicate that slower HUT results in lower activation of MSNA, suggesting that HUT-induced sympathetic activation depends partially on the speed of inclination during HUT in humans.
Abstract: Many earlier human studies have reported that increasing the tilt angle of head-up tilt (HUT) results in greater muscle sympathetic nerve activity (MSNA) response, indicating the amplitude dependen...
22 citations
TL;DR: A phantom is used for evaluating accuracy, particularly for evaluating errors intrinsic to different operating rooms, and it indicated that skin shift decreased the navigation accuracy by an error of more than 4 mm, and the gap between the marker ball and the socket resulted in a decrease in Navigation accuracy by more than 5 mm.
Abstract: Neurosurgeons sometimes find it difficult to locate tumors precisely during microsurgery, particularly tumors located in the brain parenchyma because of the absence of boundaries in this region. Image-guided neurosurgical techniques conducted with the help of neuronavigation systems have been developed and have gained importance recently. Accuracy is vital during image-guided neurosurgery. We used a phantom to evaluate the errors introduced during navigation. The three errors evaluated were skin-shift, marker-gap, and table-rotation errors. The skin-shift error occurs if the fiducial markers positioned on the scalp move when the head is fixed to a head holder with head pins. The marker-gap error occurs when the marker ball is positioned incorrectly in the marker socket. The table-rotation error occurs when the operating table is rotated for obtaining an intraoperative MR image and then returned to its original position. Our results indicated that skin shift decreased the navigation accuracy by an error of more than 4 mm, and the gap between the marker ball and the socket resulted in a decrease in navigation accuracy by an error of more than 5 mm. The table-rotation error was found to be negligible. The errors can be avoided by ensuring that the fiducial markers are positioned appropriately on the scalp and the marker ball is fitted well in the marker socket. A phantom is useful for evaluating accuracy, particularly for evaluating errors intrinsic to different operating rooms. Periodic quality assurance by use of a phantom in each operating room might aid in maintaining the accuracy of neuronavigation.
14 citations
TL;DR: A method to obtain stochastic differential equations (SDEs) as a mathematical model of the body sway on the basis of the stabilogram and succeeded in estimating the decrease in the gradient of the potential function by using an index called sparse density.
Abstract: It has been reported that even users of virtual environments and entertainment systems experience motion sickness. This visually induced motion sickness (VIMS) is known to be caused by sensory conflict, for instance, the disagreement between vergence and visual accommodation while viewing stereoscopic images. The simulator sickness questionnaire is a well-known tool that is used herein for verifying the occurrence of VIMS. We used the SSQ and also quantitatively measured head acceleration and sway of the center of gravity of the human body before and during the exposure to stereoscopic images on a head-mounted display. During the measurement, the subjects were instructed to maintain the Romberg posture for the first 60 s and a wide stance (with the midlines of heels 20 cm apart) for the next 60 s. We proposed a method to obtain stochastic differential equations (SDEs) as a mathematical model of the body sway on the basis of the stabilogram. While there are several minimal points of time-averaged potential function in the SDEs, the exposure decreases the gradient of the potential function. We have succeeded in estimating the decrease in the gradient of the potential function by using an index called sparse density.
12 citations
15 Jul 2009
TL;DR: The effect of VIMS on body sway was examined using stabilograms and the dynamics of the sway during and before the exposure was considered to be stochastic, meaning that exposure to 3D movies would not change the dynamics to a deterministic one.
Abstract: The viewers of three-dimensional (3D) movies often complain of blurring and bleeding. They sometimes experience visually induced motion sickness (VIMS). In this study, the effect of VIMS on body sway was examined using stabilograms. We measured the sway in the center of gravity before and during the exposure to images projected on a head-mounted display (HMD). While viewing, the subjects were instructed to remain in the Romberg posture for the first 60 seconds and maintain a wide stance (midline of the heels, 20 cm apart) for the next 60 seconds. Employing Double-Wayland algorithm, we measured the degree of determinism in the dynamics of the sway in the center of gravity with respect to viewing 3D movies on HMD. As a result, the dynamics of the sway during and before the exposure was considered to be stochastic. Thus, exposure to 3D movies would not change the dynamics to a deterministic one.
10 citations
01 Jan 2009
TL;DR: A method to obtain stochastic differential equations (SDEs) as a mathematical model of the body sway on the basis of the stabilogram is proposed and succeeded in estimating the decrease in the gradient of the potential function by using an index called sparse density.
Abstract: Often, people travelling in ships, trains, aircraft, and cars tend to experience motion sickness. It has been reported that even users of virtual environments and entertainment systems experience motion sickness. This visually induced motion sickness (VIMS) is known to be caused by sensory conflict, which is the disagreement between vergence and visual accommodation while observing stereoscopic images. VIMS can be measured by psychological and physiological methods. The simulator sickness questionnaire (SSQ) is a well-known method that is used herein for verifying the occurrence of VIMS. We also quantitatively measure the sway of the centre of gravity of the human body before and during exposure to several types of movies. During the measurement, subjects are instructed to maintain the Romberg posture for the first 60 s and a wide stance (with midlines of the heels 20 cm apart) for the next 60 s. The centre of gravity is projected on a plane that is parallel to the ground. The body sway is recorded as a stabilogram on the plane. According to previous research, a stochastic process is regarded as a mathematical model that generates stabilograms. We propose a method to obtain stochastic differential equations (SDEs) as a mathematical model of the body sway on the basis of the stabilogram. While there are several minimal points of the temporally averaged potential function involved in the SDEs, the stereoscopic images decrease the gradient of the potential function. We have succeeded in estimating the decrease in the gradient of the potential function by using an index called sparse density.
9 citations
01 Jan 2009
TL;DR: The findings suggested that the continuous use of DR.REX will promote a ciliary muscle-stretching effect, leading to the improvement of visual acuity.
Abstract: By relaxing the contracted focus-adjustment muscles around the eyeball, such as the ciliary and extraocular muscles, improvement of the pseudo-myopia is expected. This understanding has led to the development of an eyesight recovering apparatus called Dr.REX, which uses stereoscopic video. In this study, we verify effects of the apparatus on eyesight of myopic young persons (16M & 16F) and 12 middle-aged persons. In the Measurement 1, the young were examined in the medium-range (>10 days) effect. Moreover, the middle-aged were investigated on several trials of the eyesight recovering apparatus in the Measurement 2. As a result, the visual acuity was statistically improved by continuous DR.REX treatment. We considered that the effect of the visual acuity recovery device is temporary, but the findings suggested that the continuous use of DR.REX will promote a ciliary muscle-stretching effect, leading to the improvement of visual acuity.
8 citations
15 Jul 2009
TL;DR: The simulator sickness questionnaire (SSQ) is a well-known method used herein for verifying the occurrence of VIMS and the sway of the centre of gravity of the human body is quantitatively measured.
Abstract: Visually induced motion sickness (VIMS) is known to be caused by sensory conflict, which is the disagreement between vergence and visual accommodation while observing stereoscopic images. The simulator sickness questionnaire (SSQ) is a well-known method that is used herein for verifying the occurrence of VIMS. We quantitatively measure the sway of the centre of gravity of the human body before and during exposure to several images. During the measurement, subjects are instructed to maintain the Romberg posture for the first 60 s and a wide stance (midlines of the heels 20 cm apart) for the next 60 s. The stereoscopic images decrease the gradient of the potential function involved in the stochastic differential equations as a mathematical model of the body sway. We have succeeded in estimating the decrease in the gradient by using an index called sparse density.
8 citations
TL;DR: The findings may be useful in developing preventive strategies against physical and mental fatigue associated with prolonged HDBR, horizontal bed rest, and microgravity environments.
5 citations
13 Nov 2009
TL;DR: A new index, sparse density (SPD), of stationary stabilograms for detecting the metamorphism in the potential function of stochastic differential equations, which occurs when a human attempts to maintain an upright posture is proposed.
Abstract: We propose a new index, sparse density (SPD), of stationary stabilograms for detecting the metamorphism in the (temporally averaged) potential function of stochastic differential equations, which occurs when a human attempts to maintain an upright posture. It is known that a mathematical model of the body sway can be developed by a stochastic process. The authors have succeeded in finding the nonlinearity in the potential function. In this study, subjects in a standing position were stimulated by three-dimensional (3-D) movies on an head-mounted display (HMD). We also measured the degree of determinism in the dynamics of the sway of the center of gravity of the subjects. The Double-Wayland algorithm was used as a novel method. As a result, the dynamics of the body sway in the presence of the stimulus as well as in its absence were considered to be stochastic. The metamorphism in the potential function during exposure to the conventional 3-D images could be detected by using the SPD.
15 Jul 2009
TL;DR: This work quantitatively measured the head acceleration and body sway before and during exposure to a conventional 3D movie and employed two-way ANOVA with leg postures and presence/absence of stereoscopic images as factors.
Abstract: Visually induced motion sickness (VIMS) is caused by sensory conflict, the disagreement between vergence and visual accommodation while observing stereoscopic images. VIMS can be measured by psychological and physiological methods. We quantitatively measured the head acceleration and body sway before and during exposure to a conventional 3D movie. The subjects wore a head mount display and maintained the Romberg posture for the first 60 s and a wide stance (midlines of the heels 20 cm apart) for the next 60 s. Head acceleration was measured using an Active Tracer with 50 Hz sampling. The Simulator Sickness Questioner (SSQ) was completed immediately afterward. For the SSQ sub-scores and each index for stabilograms, we employed two-way ANOVA with leg postures and presence/absence of stereoscopic images as factors. Moreover, we assumed that the input signal was the head acceleration in the transfer system to control the body sway and estimate the transfer function.
13 Nov 2009
TL;DR: Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using the time constant of the exponential decay curve fit to maximal points during prolonged muscular contraction.
Abstract: Recently, there has been an increasing focus on the rapid reduction of muscles that are required for the bending of the hip joint during walking (flexor muscles around the hip joint) with age. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. These muscles have been implicated in falling in the elderly. In this study, we examined the smoothed surface electromyography (sEMG) of femoral rectus muscles during biofeedback training (BFT) of the dominant leg. To this end, we developed parameters for the measurement of shapes in the smoothed sEMG, and evaluated the changes in these parameters in the muscles with age. Statistical analysis indicated that it was necessary to include the time constant of the exponential decay curve fit to maximal points during prolonged muscular contraction, to evaluate the changes with age by using the smoothed sEMG during BFT. Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using the time constant.
15 Jul 2009
TL;DR: It is determined that the use of the Dr.REX apparatus improved visual acuity in both the short and medium terms, and asthenopia seemed to be less severe in subjects who used Dr.Rex than in those who performed close work on VDTs.
Abstract: Relaxing the contracted muscles involved in focus-adjustment around the eyeball, such as the ciliary body and extraocular muscles, is expected to improve pseudomyopia. This hypothesis has led to the development of Dr.REX--an apparatus for recovering eyesight by using a stereoscopic video. In this study, we verified the effects of this apparatus on visual acuity and asthenopia in the short and medium terms. Thirty-two myopic Japanese students participated in this study. We compared the severity of asthenopia in subjects who used Dr.REX and in those who performed close work on video display terminals (VDTs). We determined that the use of the apparatus improved visual acuity in both the short and medium terms. In addition, asthenopia seemed to be less severe in subjects who used Dr.Rex than in those who performed close work on VDTs.
01 Mar 2009
TL;DR: In this paper, the authors measured the gastrointestinal motility with an aim to obtain a mathematical model of EGG and to speculate factors to describe the diseases resulting from constipation and erosive gastritis.
Abstract: Electrogastrography (EGG) is an abdominal surface measurement of the electrical activity of the stomach. It is very important clinically to record and analyze multichannel EGGs, which provide more information on the propagation and co-ordination of gastric contractions. This study measured the gastrointestinal motility with an aim to obtain a mathematical model of EGG and to speculate factors to describe the diseases resulting from constipation and erosive gastritis. The waveform of the electric potential in the Cajal cells is similar to the graphs of numerical solutions to the van der Pol equation. Hence, we added the van der Pol equation to a periodic function and random white noises, which represented the intestinal motility and other biosignals, respectively. We rewrote the stochastic differential equations (SDEs) into difference equa-tions, and the numerical solutions to the SDEs were obtained by the Runge—Kutta—Gill formula as the numerical calculus, where we set the time step and initial values to be 0.05 and (0, 0.5), respectively. Pseudorandom numbers were substituted in the white noise terms. In this study, the pseudorandom num-bers were generated by the Mersenne Twister method. These numerical calculations were divided into 12000 time steps. The numerical solutions and EGG were extracted after every 20 steps. The EGG and numerical solutions were compared and evaluated by the Lyapunov exponent and translation error. The EGG was well described by the stochastic resonance in the SDEs.
01 May 2009
TL;DR: A new and smooth shrinkage function using noise distribution is designed and effective for low-dose noisy CT images when using accurately selected parameters.
Abstract: Many shrinkage functions have been introduced and applied for the wavelet shrinkage denoising of computed tomography (CT) images. However, these functions have problems in continuity of functions and cause “shrinkage artifacts”. Therefore, we designed a new and smooth shrinkage function using noise distribution. The proposed shrinkage function was designed under the following four conditions: (1) use of noise distribution, (2) shrunk coefficients having all ranges of amplitude, (3) function continuity, and (4) property of a function that is controllable by two parameters. The designed function was applied to phantom and chest CT images and denoising performance was compared with other functions. In the proposed method, edge and pixel values were maintained when compared with previous functions, the occurrence of shrinkage artifacts was smaller, and high- quality denoised images were obtained. The proposed shrinkage function is effective for low-dose noisy CT images when using accurately selected parameters.