Masticatory performance analysis using photographic image of gummy jelly.

PURPOSE: Masticatory performance can be measured through elution of glucose or beta-carotene from comminuted gummy jelly. However, these methods require special devices. Additionally, occasional/unintentional swallowing or inadequate collection of comminuted particles of gummy jelly in the oral cavity may cause measurement errors. Therefore, we devised a new photographic method to estimate the increase in surface area and weight of comminuted gummy jelly. This study aimed to verify the accuracy of this method. METHODS: Initially, fifty images depicting the comminuted pieces in a special box were prepared. Then, the increase in surface area was measured using a fully-automated method, and the weight was measured. The size and angle of each image were adjusted based on markers located at the four corners of the box. From these photographic images, the area, perimeter, color average, color deviation, side area, and amount of surface roughness for each particle was calculated, and multiple regression analysis was performed to estimate the surface area and weight. The relationship between the estimated values and the values measured with the fully-automated device and by weight were analyzed. RESULTS: The intra-class correlation coefficient between the estimated value and the value from the fully-automated method was r = 0.956. This high correlation was also obtained under different photographic conditions. Furthermore, for determining whether 80% or less gummy jelly was collected, the sensitivity was 100% and the specificity was 91%. CONCLUSIONS: The newly developed photographic method is valuable because it is accessible and may assist in achieving reliable evaluation of masticatory performance.

Pressure distribution-based texture sensing by using a simple artificial mastication system.

This paper proposes a novel texture sensing method for nursing-care gel by using an artificial mastication system, in which not only mechanical characteristics but also geometrical ones are objectively and quantitatively evaluated. When human masticates gel food, she or he perceives the changes of the shape and contact force simultaneously. Based on the impressions, they evaluate the texture. For reproducing such a procedure, the pressure distribution of gel is measured in the simple artificial mastication, and the information associated to both the geometrical and mechanical characteristics is simultaneously acquired. The relationship between the value of sensory evaluation (i.e. impression human perceives), and the pressure distribution data is numerically modeled by applying the image texture analysis. Experimental results show that the proposed method succeeds in estimating the values of sensory evaluation of nine kinds of gel with the coefficient of determination greater than 0.93.

A novel heart failure mice model of hypertensive heart disease by angiotensin II infusion, nephrectomy, and salt loading.

Although the mouse heart failure (HF) model of hypertensive heart disease (HHD) is useful to investigate the pathophysiology and new therapeutic targets for HHD, the model using simple experimental procedures and stable phenotypes has not been established. This study aimed to develop a novel mouse HF model of HHD by combining salt loading and uninephrectomy with ANG II infusion. Eight-week-old C57BL/6 male mice were treated with ANG II infusion (AT), ANG II infusion and uninephrectomy (AN), ANG II infusion and salt loading (AS), or ANG II infusion, uninephrectomy, and salt loading (ANS). Systolic blood pressure was significantly elevated and left ventricular (LV) hypertrophy was found in AT, AN, AS, and ANS mice, and there were no significant differences in those parameters between the four groups. At 6 wk after the procedures, only ANS mice showed significant decreases in LV fractional shortening and increases in lung weight with a high incidence. This phenotype was reproducible, and there were few perioperative or early deaths in the experimental procedures. Severe LV fibrosis was found in ANS mice. Oxidative stress was enhanced and small GTPase Rac1 activity was upregulated in the hearts of ANS mice. After the addition of salt loading and uninephrectomy to the ANG II infusion mouse model, cardiac function was significantly impaired, and mice developed HF. This might be a novel and useful mouse HF model to study the transition from compensated LV hypertrophy to HF in HHD.

A device for the rapid transfer/transplantation of living cell sheets with the absence of cell damage.

In this study, we developed a device that could easily, rapidly, and completely transfer cell sheets from one material to another or transplant cell sheets onto the dorsal subcutaneous tissues of rats without leaving residual cells. Because the manipulation is as simple as pipetting, technical expertise is not required to transfer cell sheets very rapidly (the transfer time was 3.7 ± 1.6 s) using the device compared with that of a conventional method using a pipette (430 ± 180 s). After transfer by the device, C2C12 skeletal myoblast sheets showed active cell metabolism, cell viability, and very high production of vascular endothelial growth factor and stromal-derived factor-1α, indicating transfer without cell damage. Cardiac cell sheets after transfer showed spontaneous and synchronous beating, indicating intact cell-cell junctions and ion channel proteins on the cell surface. In addition, the device allowed us to transfer C2C12 cell sheets onto soft, rugged and curved surfaces such as human hands. Furthermore, cardiac cell sheets adhered rapidly and tightly onto the dorsal subcutaneous tissues of rats. This transfer/transplantation device may be a powerful tool in cell sheet-based tissue engineering and regenerative medicine.

Interleukin-16 promotes cardiac fibrosis and myocardial stiffening in heart failure with preserved ejection fraction.

BACKGROUND: Chronic heart failure (CHF) with preserved left ventricular (LV) ejection fraction (HFpEF) is observed in half of all patients with CHF and carries the same poor prognosis as CHF with reduced LV ejection fraction (HFrEF). In contrast to HFrEF, there is no established therapy for HFpEF. Chronic inflammation contributes to cardiac fibrosis, a crucial factor in HFpEF; however, inflammatory mechanisms and mediators involved in the development of HFpEF remain unclear. Therefore, we sought to identify novel inflammatory mediators involved in this process. METHODS AND RESULTS: An analysis by multiplex-bead array assay revealed that serum interleukin-16 (IL-16) levels were specifically elevated in patients with HFpEF compared with HFrEF and controls. This was confirmed by enzyme-linked immunosorbent assay in HFpEF patients and controls, and serum IL-16 levels showed a significant association with indices of LV diastolic dysfunction. Serum IL-16 levels were also elevated in a rat model of HFpEF and positively correlated with LV end-diastolic pressure, lung weight and LV myocardial stiffness constant. The cardiac expression of IL-16 was upregulated in the HFpEF rat model. Enhanced cardiac expression of IL-16 in transgenic mice induced cardiac fibrosis and LV myocardial stiffening accompanied by increased macrophage infiltration. Treatment with anti-IL-16 neutralizing antibody ameliorated cardiac fibrosis in the mouse model of angiotensin II-induced hypertension. CONCLUSION: Our data indicate that IL-16 is a mediator of LV myocardial fibrosis and stiffening in HFpEF, and that the blockade of IL-16 could be a possible therapeutic option for HFpEF.

Noncontact active sensing for viscoelastic parameters of tissue with coupling effect.

Living soft tissues have two characteristics for an external force. One is the coupling effect (see Fig. 1) where the tissue deforms not only at the point of application of force but also at its surrounding area without any external force. The other is the direction-dependent response (see Fig. 2) where the response during the loading phase (when the force is applied with increasing displacement) is quicker than that during the unloading phase (when the force is shutdown). In order to represent these characteristics, this paper first proposes a single layered 3-D tissue model constructed by a network composed of two stiffness and two damping parameters, respectively. For such a single-layered model, we solve the inverse problem where four unknown viscoelastic parameters are obtained by assuming that both the applied force and surface deformation of the tissue are given with respect to time. Through both simulation and experimental results, we show that this model can describe good inherent characteristics of soft tissues, namely a direction-dependent response and a coupling effect.

Balloon type elasticity sensing for left ventricle of small laboratory animal.

This paper describes an elasticity sensing system for left ventricle of small laboratory animal. We first show the basic concept of the proposed method, where a ring shaped specimen is dilated by a balloon type probe using a pressure based control, and the elasticity of the specimen is estimated by using the stress and strain information. We introduce a dual cylinder model for approximating the strengths of the specimen's material and the balloon. Based on this model, we can derive Young's modulus of the specimen. After explaining the developed experimental system, we show a couple of experimental results using rats and mice, where HFPEF (Heart Failure Preserved Ejection Fraction) group can be distinguished from a normal group.

Cell Sheet Stiffness Sensing without taking out from culture liquid.

Stiffness could be an important index for evaluating the vitality of cell sheet. This paper challenges the measurement of stiffness of transparent cell sheet in culture liquid without taking it out from petri dish. The system is composed of a micro air nozzle for supplying an air jet and a regular reflective type laser sensor for measuring the the deformation of transparent cell sheet. This system is called as Cell Sheet Stiffness Sensing system (CS(3) system). When an air jet is given to a cell sheet in culture liquid, it pushes away the liquid toward the outer direction at initial phase and reaches the surface of cell sheet. Without any switching motion, the air jet continuously imparts a force to the surface of cell sheet so that the sensor can measure the stiffness of the cell sheet.

Point-type non-contact stiffness sensing of soft tissue with coupling effect.

This paper discusses the point-type non-contact active sensing for evaluating the stiffness of a soft tissue with coupling effect. Tfhe sensing system imparts a point force to a tissue and measures the displacement at the point of application of force. The benefit is that such point based information enables us to estimate two stiffness parameters constructing the 3D spring network tissue model. Through the experiment for a human skin, we show that the deformation shapes between human skin surface and the model with the estimated parameters are nicely coincident.

Noninvasive assessment of wall distensibility with the evaluation of diastolic epicardial movement.

BACKGROUND: Left ventricular (LV) wall stiffening plays an important role in the development of heart failure with preserved ejection fraction (HFpEF). Based on the linear elastic theory, we hypothesized that the evaluation of epicardial movement during diastole is helpful for the noninvasive assessment of LV wall distensibility. METHODS AND RESULTS: Based on the linear elastic theory, the epicardial movement index (EMI) was calculated on the echocardiogram as: [see text.] We calculated diastolic wall strain (DWS) as follows to examine whether DWS substitutes for EMI: [see text.] The animal study using hypertensive Dahl salt-sensitive rats, HFpEF model, and normotensive Dahl rats showed the significant and inverse correlation of EMI or DWS with myocardial stiffness constant. Preload alteration did not affect EMI or DWS. In the clinical study, the HFpEF patients had lower EMI and DWS than the normal volunteers and the asymptomatic patients with LV hypertrophy. CONCLUSIONS: The evaluation of epicardial movement may be useful in noninvasively assessing wall distensibility in the absence of LV systolic dysfunction.

Active sensing for viscoelastic tissue with coupling effect.

This paper discusses active sensing for detecting viscoelastic parameters of living tissues with the coupling effect among neighbors. Supposing that both applied force and surface deformation of tissue are known with respect to time, we obtain viscoelastic parameters of living tissue by utilizing a single layered model with horizontal and vertical units where each unit is composed of both stiffness and damping elements. We show that the model with only appropriate number of units can nicely express the dynamic characteristic of human skin.

Improvement of touch sensitivity by pressing.

It is really interesting to know how a blood flow has an influence on a touch sensitivity during human fingertip exploration over an environment. In this paper, we examine experimentally how the touch sensitivity is changed under the condition that the blood flow is interrupted compulsorily by pressing the proximal phalange of human finger. Through the weight discrimination test based on Weber's Law, we found that the touch sensitivity improves temporarily with the statistical significance test of below 0.1 %, when a finger proximal phalange is bound and pressed. Experimental results also show that there exists a meaningful correlationship between the stiffness of fingertip and the touch sensitivity.