Dilation Ratio Research Articles

A Multialgorithm Analysis of Three Iris Biometric Sensors

The issue of interoperability between iris sensors is an important topic in large-scale and long-term applications of iris biometric systems. This work compares three commercially available iris sensors and three iris matching systems and investigates the impact of cross-sensor matching on system performance in comparison to single-sensor performance. Several factors which may impact single-sensor and cross-sensor performance are analyzed, including changes in the acquisition environment and differences in dilation ratio between iris images. The sensors are evaluated using three different iris matching algorithms, and conclusions are drawn regarding the interaction between the sensors and the matching algorithm in both the cross-sensor and single-sensor scenarios. Finally, the relative performances of the three sensors are compared.

Assessment of transient ischemic dilation (TID) ratio in gated SPECT myocardial perfusion imaging (MPI) using regadenoson, a new agent for pharmacologic stress testing.

Abnormal values of the transient ischemic dilation (TID) ratio are associated with severe and extensive coronary artery disease (CAD). The objective of this study was to determine the relationship between TID, determined from stress and rest ventricular volumes during regadenoson gated single-photon emission computed tomography myocardial perfusion imaging (MPI) dual isotope studies, and the extent of CAD found during coronary angiography. 195 patients who underwent dual isotope MPI with regadenoson and cardiac angiography between March 2009 and February 2010 were analyzed. TID was calculated using commercially available software, Emory Cardiac Toolbox. Mean TID values were compared across disease types. A threshold for abnormal TID was determined by adding two standard deviations (SDs) to the mean TID of the "non-obstructive CAD" subgroup. In the 195-patient group analyzed, the mean TID ratio for non-obstructive CAD (n = 104) was found to be 1.09 with a SD of 0.15. In a subgroup of patients whose angiogram was within 3 months of MPI (n = 155), the mean TIDs for non-obstructive disease (n = 81), single-vessel disease (n = 35), and multi-vessel disease (n = 39) were 1.09, 1.15, and 1.19 with SDs of 0.16, 0.19, and 0.26, respectively. Those with an abnormal TID had a crude and adjusted odds ratio of 3.4 for multi-vessel disease which was statistically significant. History of diabetes was not found to be a significant confounder, effect modifier, or mediator of the relationship between the TID and the vessel disease. The mean TID ratio in patients with multi-vessel disease was 1.19. The threshold for an abnormal TID was 1.39 with specificity of 95% and sensitivity of 15% for determining multi-vessel CAD status. We conclude that the level of TID in gated SPECT MPI using regadenoson is associated with the degree of CAD on angiography.

Preload dependence of gated cardiac SPECT-derived ventricular volumes in hemodialysis patients

BackgroundIn hemodialysis (HD) patients, the intravascular volume expansion of the pre-HD state leads to a high preload. We aim to examine its effect on myocardial perfusion gated SPECT (MPGS)-derived left ventricular (LV) volumes. MethodsThe study comprised 50 end-stage renal disease (ESRD) patients on HD with normal 2-day stress/rest MPGS performed for kidney transplantation risk assessment. Patients (pts) comprised 23 men/27 women, with mean age of 59.4 ± 7.1 years. The time elapsed from the last HD session in hours was calculated on both days, and patients were classified according to whether it was higher (group A: 19 pts), lower (group B: 27 pts), or equal (group C: 4 pts) on the stress vs the rest day. End-diastolic, end-systolic volumes (EDV, ESV), and left ventricular ejection fraction (LVEF) were determined using QGS™ software. Transient ischemic dilation (TID) ratios were derived from the nongated images using QPS™ software. ResultsVolumes were significantly higher at stress in group A, at rest in group B, and similar in group C. TID ratios were significantly higher in group A vs groups B and C. ConclusionsMPGS-derived ventricular volumes are preload dependent. The high preload of the pre-HD state may mimic ischemic TID if occurring on the stress day and create confusion if coinciding with the rest day.

Terumo-Triplex grafts for total arch replacement: analysis of postoperative graft performance

We evaluated the performance of Terumo-Triplex (TRP) with a large-diameter vascular graft sealed with non-biodegradable material in 48 patients who underwent total arch replacement under selective cerebral perfusion between 2004 and 2009. TRP grafts were used in 13 patients (T group), Gelseal graft in 15 (G group), Hemashield graft in 10 (H group) and Intergard graft in 10 (I group). The total tube drainage, time to tube removal, graft dilation ratio and inflammation were evaluated postoperatively. Cardiopulmonary bypass and selective cerebral perfusion times did not differ between groups. Two patients died in hospital. The total drain drainage was significantly lower in the T group (956±156ml) than in the H (2058±403ml, p=0.001) or I (5959±1027ml, p=0.01) groups. The time to tube removal was significantly lower in T group and G group than H and I group (T: 3.7±0.4, G: 4.1±0.4, H: 8.3±1.6, I: 18.6±3.6days, T vs. H, I: p=0.07, 0.0002, G vs. H, I: p=0.004, <0.0001). The graft dilation ratio was significantly lower in T group than G group (T: 104±4 vs. 130±7%, p=0.001). The max C-reactive protein level was significantly lower in T group (16.2±4.5mg/dl) than in the G group (19.4±3.2mg/dl, p=0.047), H (20.4±4.1mg/dl, p=0.048), or I (20.5±4.5mg/dl, p=0.013) groups. Maximum body temperature was also lower in the T group (38.2±0.5°C) than in the G (38.7±0.4°C, p=0.011), H (38.9±0.6°C, p=0.0087), and I (39.3±0.7°C, p=0.0005). Thus, TRP graft might attenuate inflammatory response compared to the other sealed grafts for total arch replacement in patients with aortic arch aneurysm or dissection.

Transient Ischemic Dilation Ratio in 82Rb PET Myocardial Perfusion Imaging: Normal Values and Significance as a Diagnostic and Prognostic Marker

In myocardial perfusion SPECT, transient ischemic dilation ratio (TID) is a well-established marker of severe ischemia and adverse outcome. However, its role in the setting of (82)Rb PET is less well defined. We analyzed 265 subjects who underwent clinical rest-dipyridamole (82)Rb PET/CT. Sixty-two subjects without a prior history of cardiac disease and with a normal myocardial perfusion study had either a low or a very low pretest likelihood of coronary artery disease or negative CT angiography. These subjects were used to establish a reference range of TID. In the remaining 203 patients with an intermediate or high pretest likelihood, subgroups with normal and abnormal TID were established and compared with respect to clinical variables, perfusion defect scores, left ventricular function, and absolute myocardial flow reserve. Follow-up was obtained for 969 ± 328 d to determine mortality by review of the social security death index. In the reference group, TID ratio was 0.98 ± 0.06. Accordingly, a threshold for abnormal TID was set at greater than 1.13 (0.98 + 2.5 SDs). In the study group, 19 of 203 patients (9%) had an elevated TID ratio. Significant differences between subgroups with normal and abnormal TID ratio were observed for ejection fraction reserve (5.0 ± 6.4 vs. 1.8 ± 7.9; P < 0.05), difference between end-systolic volume (ESV) at rest and stress (ΔESV[stress-rest]; 1.8 ± 7.4 vs. 12.3 ± 13.0 mL; P < 0.0001), difference between end-diastolic volume (EDV) at rest and stress (ΔEDV[stress-rest]; 10.8 ± 11.5 vs. 23.8 ± 14.6 mL; P < 0.0001), summed rest score (1.8 ± 3.8 vs. 3.8 ± 7.6; P < 0.05), summed stress score (3.0 ± 5.4 vs. 7.5 ± 9.8; P < 0.002), summed difference score (1.3 ± 2.6 vs. 3.7 ± 5.3; P < 0.02), and global myocardial flow reserve (2.1 ± 0.8 vs. 1.7 ± 0.6; P < 0.02). Additionally, TID-positive patients had a significantly lower overall survival probability (P < 0.05). In a subgroup analysis of patients without regional perfusion abnormalities, TID-positive patients' overall survival probability was significantly smaller (P < 0.03), and TID was an independent predictor (exponentiation of the B coefficients [Exp(b)] = 6.22; P < 0.009) together with an ejection fraction below 45% (Exp[b] = 6.16; P < 0.002). The present study suggests a reference range of TID for (82)Rb PET myocardial perfusion imaging that is in the range of previously established values for SPECT. Abnormal TID in (82)Rb PET is associated with more extensive left ventricular dysfunction, ischemic compromise, and reduced global flow reserve. Preliminary outcome analysis suggests that TID-positive subjects have a lower overall survival probability.

Automated quantitative Rb-82 3D PET/CT myocardial perfusion imaging: Normal limits and correlation with invasive coronary angiography

We aimed to characterize normal limits and to determine the diagnostic accuracy for an automated quantification of 3D 82-Rubidium (Rb-82) PET/CT myocardial perfusion imaging (MPI). We studied 125 consecutive patients undergoing Rb-82 PET/CT MPI, including patients with suspected coronary artery disease (CAD) and invasive coronary angiography, and 42 patients with a low likelihood (LLk) of CAD. Normal limits for perfusion and function were derived from LLk patients. QPET software was used to quantify perfusion abnormality at rest and stress expressed as total perfusion deficit (TPD). Relative perfusion databases did not differ in any of the 17 segments between males and females. The areas under the receiver operating characteristic curve for detection of CAD were 0.86 for identification of ≥50% and ≥70% stenosis. The sensitivity/specificity was 86%/86% for detecting ≥50% stenosis and 93%/77% for ≥70% stenosis, respectively. In regard to normal limits, mean rest and stress left ventricular ejection fraction (LVEF) were 67% ± 10% and 75% ± 9%, respectively. Mean transient ischemic dilation ratio was 1.06 ± 0.14 and mean increase in LVEF with stress was 7.4% ± 6.1% (95th percentile of 0%). Normal limits have been established for 3D Rb-82 PET/CT analysis with QPET software. Fully automated quantification of myocardial perfusion PET data shows high diagnostic accuracy for detecting obstructive CAD.

A study on thermal-diffusion and diffusion-thermo effects in a two-dimensional viscous flow between slowly expanding or contracting walls with weak permeability

The present study investigates the thermal-diffusion and diffusion-thermo effects of a viscous fluid in a two-dimensional channel between slowly expanding or contracting walls with weak permeability. Assuming symmetric injection or suction along the uniformly expanding porous walls and using similarity transformation, the governing flow equations are reduced to nonlinear ordinary differential equations. The resulting equations are then solved analytically using a perturbation technique in permeation Reynolds number and wall dilation ratio. The effects of various physical parameters on flow variables have been discussed numerically and explained graphically.

Free-radical scavenger edaravone inhibits both formation and development of abdominal aortic aneurysm in rats

An ideal pharmaceutical treatment for abdominal aortic aneurysm (AAA) is to prevent aneurysm formation and development (further dilatation of pre-existing aneurysm). Recent studies have reported that oxidative stress with reactive oxygen species (ROS) is crucial in aneurysm formation. We hypothesized that edaravone, a free-radical scavenger, would attenuate vascular oxidative stress and inhibit AAA formation and development. An AAA model induced with intraluminal elastase and extraluminal calcium chloride was created in 42 rats. Thirty-six rats were divided three groups: a low-dose (group LD; 1 mg/kg/d), high-dose (group HD; 5 mg/kg/d), and control (group C, saline). Edaravone or saline was intraperitoneally injected twice daily, starting 30 minutes before aneurysm preparation. The remaining six rats (group DA) received a delayed edaravone injection (5 mg/kg/d) intraperitoneally, starting 7 days after aneurysm preparation to 28 days. AAA dilatation ratio was calculated. Pathologic examination was performed. ROS expression was semi-quantified by dihydroethidium staining and the oxidative product of DNA induced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), by immunohistochemical staining. At day 7, ROS expression and 8-OHdG-positive cells in aneurysm walls were decreased by edaravone treatment (ROS expression: 3.0 ± 0.5 in group LD, 1.7 ± 0.3 in group HD, and 4.8 ± 0.7 in group C; 8-OHdG-positive cells: 106.2 ± 7.8 cells in group LD, 64.5 ± 7.7 cells in group HD, and 136.6 ± 7.4 cells in group C; P < .0001), compared with group C. Edaravone treatment significantly reduced messenger RNA expressions of cytokines and matrix metalloproteinases (MMPs) in aneurysm walls (MMP-2: 1.1 ± 0.5 in group LD, 0.6 ± 0.1 in group HD, and 2.3 ± 0.4 in group C; P < .001; MMP-9: 1.2 ± 0.1 in group LD, 0.2 ± 0.6 in group HD, and 2.4 ± 0.2 in group C; P < .001). At day 28, aortic walls in groups LD and HD were less dilated, with increased wall thickness and elastin content than those in group C (dilatation ratio: 204.7% ± 16.0% in group C, 156.5% ± 6.6% in group LD, 136.7% ± 2.0% in group HD; P < .0001). Delayed edaravone administration significantly prevented further aneurysm dilatation, with increased elastin content (155.2% ± 2.9% at day 7, 153.1% ± 11.6% at day 28; not significant). Edaravone inhibition of ROS can prevent aneurysm formation and expansion in the rat AAA model. Free-radical scavenger edaravone might be an effective pharmaceutical agent for AAA in clinical practice.

Diagnostic Value of Left Ventricular Dyssynchrony After Exercise and at Rest in the Detection of Multivessel Coronary Artery Disease on Single-Photon Emission Computed Tomography

Although stress-induced left ventricular (LV) wall motion abnormality is a well-known marker for extensive coronary artery disease (CAD), no study has yet analyzed whether phase analysis of exercise-induced LV mechanical dyssynchrony may have enhanced diagnostic value over conventional perfusion analysis in the detection of multivessel CAD. A total of 278 patients with suspected or confirmed CAD underwent both exercise stress (99m)Tc-sestamibi gated single-photon emission computed tomography and coronary angiography. LV mechanical dyssynchrony was evaluated using the SyncTool to obtain the phase SD and histogram bandwidth. In the detection of 128 patients with multivessel CAD, a summed stress score (SSS) of ≥9 showed a sensitivity of 84% and a specificity of 53%, while an increase in phase SD of ≥4.4° and a bandwidth of ≥14° after exercise had sensitivities of 74% and 68%, and specificities of 84% and 91%, respectively. On multivariate analysis the combination of post-stress increases in phase SD, histogram bandwidth, transient ischemic dilation (TID) ratio and SSS best identified multivessel CAD (sensitivity 77%, specificity 88%, χ(2)=181.8), compared with TID ratio and SSS only (sensitivity 70%, specificity 76%, χ(2)=68.9). The addition of phase analysis to evaluate exercise-induced LV mechanical dyssynchrony on conventional perfusion analysis enabled better identification of patients with multivessel CAD.

On the boundary behavior of solutions of the Beltrami equations

We show that any homeomorphic solution of the Beltrami equation v from the Sobolev class W loc 1,1 is a so-called lower Q-homeomorphism with Q(z) = K μ(z), where K μ(z) is the dilatation ratio of this equation. On this basis, we develop the theory of boundary behavior and removing of singularities of these solutions.

Abstract 18192: Free Radical Scavenger Edaravone Inhibited Both Aneurysmal Formation and Progression in Rat Abdominal Aortic Aneurysm Model

Objective: Effective pharmaceutical treatment for abdominal aortic aneurysm (AAA) has not been established. Recent studies have reported that reactive oxygen species (ROS) are excessively expressed in the aneurysm wall. However, whether ROS play a crucial role in the aneurysm formation and its growth still remains unknown. We investigate ROS inhibition with the free radical scavenger edaravone effectively prevents aneurysm formation. Methods: Thirty male Sprague-Dawely rats were used to create experimental AAA model. Rats were divided into three groups; group C (control) received an intraperitoneal injection of saline at 30 minutes prior to the aneurysm preparation, group E (edaravone-early-treated) received an intraperitoneal injection of edaravone 5 mg/kg/day at 30 minutes prior to the aneurysm preparation, and the edaravone-late-treated group (group L) received the same dose of edaravone at 7 days after AAA preparation. At day 7, ROS production was semiquantified by dihydroethidium staining, and the oxidative product of DNA induced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), by immunohistochemical staining. The dilatation ratio of AAA at day 28 was calculated. Results: At day 7, dihydroethidium staining of aneurysm wall showed that ROS expression was significantly suppressed in group E compared with groups C and L (2.1±0.7 in group E, 4.3±1.8 in groups C and L, p=0.02). Positive cell count of 8-OHdG was significantly lower in group E than that in groups C and L. The aortic dilatation ratio (%) at day 28 in groups E was significantly lower than that in group C (36.7±2.0 vs. 104.7±16.0, p&lt; 0.001) and in group L was significantly lower than that in group C (53.1±2.9 vs. 104.7±16.0, p&lt; 0.001). Conslusion: ROS play a crucial role in the aneurysm formation. Edaravone treatment starting even at 7 days after aneurysm preparation completely inhibited aneurysmal growth. Edaravone could be effective pharmaceutical agent for AAA in clinical practice.

Fabric dilatancy and the plasticity modeling of granular media

SUMMARYA novel conceptual model of the mechanics of sands is developed within an elastic–plastic framework. Central to this model is the realization that volume changes in anisotropic granular materials occur as a result of two fundamentally different mechanisms. The first is purely kinematic, dilative, and is the result of the changes in anisotropic fabric. There is also a second volume change in granular media that occurs as a direct response to changes in stress as in a standard elastic/plastic continuum. The inclusion of the two sources of volume change results in three important datum states. When subjected to isotropic strains, the resulting stress state in granular materials is not isotropic but lies upon the kinematic normal consolidation line. There exists a state at which the fabric‐induced volumetric strain rate becomes equal to the stress‐induced volumetric strain rate making the total plastic volumetric strain rate equal to zero. Granular response changes from contractive to dilative at this phase transformation line. The third datum state is the one in which the stress‐induced volumetric strain rate is zero. The sand, however, continues to dilate at this state with the difference between stress and dilation ratio a constant as predicted by Taylor's stress–dilatancy rule. These predictions are shown in accordance with experimental data from a series of drained tests and undrained on Ottawa sand. Copyright © 2011 John Wiley &amp; Sons, Ltd.

Combining two potential causes of metalloproteinase secretion causes abdominal aortic aneurysms in rats: a new experimental model

Progress in understanding the pathophysiology of abdominal aortic aneurysms (AAA) is dependent in part on the development and application of effective animal models that recapitulate key aspects of the disease. The objective was to produce an experimental model of AAA in rats by combining two potential causes of metalloproteinase (MMP) secretion: inflammation and turbulent blood flow. Male Wistar rats were randomly divided in four groups: Injury, Stenosis, Aneurysm and Control (40/group). The Injury group received a traumatic injury to the external aortic wall. The Stenosis group received an extrinsic stenosis at a corresponding location. The Aneurysm group received both the injury and stenosis simultaneously, and the Control group received a sham operation. Animals were euthanized at days 1, 3, 7 and 15. Aorta and/or aneurysms were collected and the fragments were fixed for morphologic, immunohistochemistry and morphometric analyses or frozen for MMP assays. AAAs had developed by day 3 in 60-70% of the animals, reaching an aortic dilatation ratio of more than 300%, exhibiting intense wall remodelling initiated at the adventitia and characterized by an obvious inflammatory infiltrate, mesenchymal proliferation, neoangiogenesis, elastin degradation and collagen deposition. Immunohistochemistry and zymography studies displayed significantly increased expressions of MMP-2 and MMP-9 in aneurysm walls compared to other groups. The haemo-dynamic alterations caused by the stenosis may have provided additional contribution to the MMPs liberation. This new model illustrated that AAA can be multifactorial and confirmed the key roles of MMP-2 and MMP-9 in this dynamic remodelling process.

Keeping an eye on the truth: Pupil size, recognition memory and malingering

Background: Estimates of the incidence of malingering in patient populations vary from 1 to 12%, rising to ∼25% in patients seeking financial compensation. Malingering is particularly difficult to detect when patients feign poor performance on neuropsychological tests (see Hutchinson, 2001). One strategy to detect malingering has been to identify psychophysiological markers associated with deception. Tardif, Barry, Fox and Johnstone (2000) used electroencephalogram (EEG) recording to measure event related potentials (ERPs) during a standard recognition memory test. Previous research has documented an ERP “old/new effect” – late positive parietal ERPs are larger when participants view old, learned words compared to new words during recognition. Tardif et al. reasoned that if this effect is not under conscious control, then it should be equally detectable in people feigning amnesia as in participants performing to their best ability. As predicted, they found no difference in the magnitude and topography of the old/new ERP effect between participants who were asked to feign amnesia whilst performing the test and those asked to perform to their best ability. Whilst this approach shows some promise, EEG is comparatively time consuming and expensive. Previous research has shown that during recognition memory tests, participants' pupils dilate more when they view old items compared to new items (Otero, Weeks, and Hutton, 2006; Vo et al., 2008). This pupil “old/new effect” may present a simpler means by which to establish whether participants are feigning amnesia. Method: We used video-based oculography to compare changes in pupil size during a recognition memory test when participants were given standard recognition memory instructions, instructions to feign amnesia and instructions to report all items as new. Due to constant fluctuation in pupil size over time, and variation between individuals, a pupil dilation ratio (PDR) was calculated that represented the maximum pupil size during the trial as a proportion of the maximum during baseline. Results: Participants' pupils dilated more to old items compared to new items under all three instruction conditions (F(1.25) = 47.02, MSE < 0.001, p < .001, ηp2 = .65). There were no significant differences between baseline pupil size (F(1.63,40.76) = 1.90, p = .17, ns). Conclusions: The finding that under standard recognition memory instructions, participants' relative increase in pupil size is greater when they view old items compared to new items replicates previous research documenting the pupil old/new effect. That the effect persists, even when participants give erroneous responses during recognition, suggests that the “pupil old/new effect” is not under conscious control and may therefore have potential use in clinical settings as a simple means with which to detect whether patients are feigning amnesia.

Histological evaluation of bronchial tissue from elderly individuals with bronchial asthma

We studied morphologic and morphometric characteristics of the bronchial walls in lungs obtained at autopsy form elderly patients who had had bronchial asthma. Thirteen patients (age at time of death 57 to 98 years; average, 81 years) were divided into three groups: AS, died of severe asthma attack (n = 4); AC, admitted with asthma symptoms but died of other diseases (n = 6); and NA, died of other diseases and had had no asthma symptoms in the year before death (n = 3). Lungs from ten non-smokers with no history of bronchial asthma or other lung disorders were used as control. Transverse sections of segmental and subsegmental bronchi were prepared, and four quantities were analyzed: 1) the ratio of total bronchial gland area to total area of the bronchial wall (Yamanaka index), 2) the thickness of the basement membrane, 3) the thickness of the smooth muscle bundle, and 4) the ratio of luminal area to total area of the bronchial wall (bronchial dilation ratio). In the AS group, the Yamanaka index and the thickness of the smooth muscle bundles and of the basement membrane were significantly greater than those in the control group at both the segmental and subsegmental levels, with massive eosinophil infiltration into the bronchial walls. Furthermore the bronchial dilation ratio at the subsegmental level correlated closely with the Yamanaka index. Thickness of the smooth muscle bundle seemed to be most representative of the severity of asthma symptoms. In conclusion, morphometric findings of bronchial walls in elderly patients with asthma symptoms seem to be similar to those in their younger counterparts.

Quality improvement of a β-type titanium alloy cast for biomedical applications by using a calcia mold

The applicability of a calcia mold to casting a β-type titanium alloy, Ti–29Nb–13Ta–4.6Zr (TNTZ), was evaluated with focusing on the dimensional accuracy of the casting in this study. Pure zirconium particles were added to a calcia mold to take advantage of the expansion of oxidized zirconium during the baking process in order to compensate for the solidification shrinkage of TNTZ. The morphological characteristics of the casting surface, such as the roughness and dimensional accuracy, of the cast TNTZ were investigated. The dilation ratio of the calcia mold is found to increase with increasing the number of pure zirconium particles. The addition of 12 mass% or 14 mass% pure zirconium particles compensates for not only the solidification of TNTZ but also the occurrence of shrinkage of the calcia mold. In addition, the formation of a surface reaction layer in TNTZ is restrained to a larger extent by casting into a calcia mold than into a magnesia mold, which is the conventional investment mold for titanium casting. Furthermore, the volume fraction and number of casting defects are also restrained to a larger extent by casting into a calcia mold than into a magnesia mold. The results of this study should lead to enhancements in the creation of cast TNTZ for dental products.

Transient ischemic dilatation ratio derived from myocardial perfusion scintigraphy: What are we looking at?

BackgroundElevated transient ischemic dilatation (TID) ratio during myocardial perfusion imaging (MPI) is described as a marker of severe CAD, even in acquisitions with normal perfusion. This was initiated to explore the effects of stressor type on the TID. Additionally the relation between the TID and other functional parameters, such as end diastolic volume (EDV), end systolic volume (ESV), and left ventricle ejection fraction (LVEF), heart rate (HR), and severity of ischemia, was evaluated. MethodA total of 299 consecutive patients referred for a 2-day stress/rest MPI protocol were included. Patients were stressed with either adenosine (n = 164) or exercise (n = 135). MPI data were analyzed with an automated software tool to determine TID, EDV, ESV, LVEF, SSS, and SDS. The SDS was used to quantify the degree of ischemia, with a SDS ≥ 3 considered ischemic. ResultsComparison of the adenosine and exercise stressed population revealed significant differences, especially in parameters derived from the poststress acquisition. Within the exercise stressed population, TID was proportional with the SDS (R2 = .12); whereas the adenosine population did not show such a relation (R2 = .001). Difference in HR between rest and poststress acquisitions showed high levels of linear regression with TID values of both the adenosine (R2 = .41) and exercise (R2 = .29) stressed population. ConclusionIn an exercise stressed population, TID is determined by both the degree of ischemia and the heart-rate difference between the two acquisition moments. TID within the adenosine population was found to be highly proportional with the HR, rather than with the degree of ischemia.

Quality Improvement of a &amp;beta;-Type Titanium Alloy Cast for Biomedical Applications by Using a Clacia Mold

The applicability of a calcia mold to casting a � -type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), was evaluated with focusing on the dimensional accuracy of the casting in this study. Pure zirconium particles were added to a calcia mold to take advantage of the expansion of oxidized zirconium during the baking process in order to compensate for the solidification shrinkage of TNTZ. The morphological characteristics of the casting surface, such as the roughness and dimensional accuracy, of the cast TNTZ were investigated. The dilation ratio of the calcia mold is found to increase with increasing the number of pure zirconium particles. The addition of 12 mass% or 14 mass% pure zirconium particles compensates for not only the solidification of TNTZ but also the occurrence of shrinkage of the calcia mold. In addition, the formation of a surface reaction layer in TNTZ is restrained to a larger extent by casting into a calcia mold than into a magnesia mold, which is the conventional investment mold for titanium casting. Furthermore, the volume fraction and number of casting defects are also restrained to a larger extent by casting into a calcia mold than into a magnesia mold. The results of this study should lead to enhancements in the creation of cast TNTZ for dental products. [doi:10.2320/matertrans.L-M2009827]

A novel rat model of abdominal aortic aneurysm using a combination of intraluminal elastase infusion and extraluminal calcium chloride exposure

An ideal animal model of abdominal aortic aneurysm (AAA) is of great importance for clarifying unknown complex mechanisms of the pathogenesis. We introduce a new, simple technique to create reliable AAAs that simulate human aneurysms. Experimental models of AAAs were created in 71 rats by means of a 20-minute application of intraluminal elastase (30 U) and extraluminal calcium chloride (0.5M) in the 1-cm segment of infrarenal abdominal aorta (group EC, n = 26). A single application of elastase (group E, n = 24) or calcium chloride (group C, n = 21) was used as control. The treated aorta in each group was measured under physiologic conditions and harvested at 1 and 4 weeks. Successful AAA formation was defined as a dilation ratio >50%. Inflammatory response, elastolytic activity, and histology in the treated aorta were evaluated among the three groups. The surgical procedure in each group was similarly completed for approximate 30 minutes and performed without any technical failure or operative death. At 4 weeks, the dilation ratio and wall thickness were 94.8% +/- 9.9% and 125.4 +/- 5.6 microm in group EC, 43.3% +/- 6.3% and 149.6 +/- 6.5 microm in group E, and 10.9% +/- 4.2% and 152.9 +/- 7.2 microm in group C. The success rate of AAA formation in group EC (92.7%) was significantly higher than that in group E (25.0%) and group C (0.0%). Less elastin content in the aortic wall was observed in group EC. At 1 week, tumor necrosis factor-alpha and interleukin-1beta messenger RNA (mRNA) expressions were significantly upregulated, and CD3+ and CD11b+ cells were significantly infiltrated into the treated aorta of group EC, compared with groups E or C. Gelatinolytic activities and mRNA expressions of matrix metalloproteinase (MMP)-2 and MMP-9 were also significantly activated in group EC. The rat AAA model using a combination of intraluminal elastase infusion and extraluminal calcium chloride exposure is simple and easy to perform and is highly reliable and reproducible to create a saccular aneurysm similar to human AAAs. This model could be more useful to clarify AAA pathogenesis, mechanisms, and treatment interventions in experimental researches.

Comparing Imperfection Ratio and Imperfection Index for Graph Classes

Perfect graphs constitute a well-studied graph class with a rich structure, reflected by many characterizations with respect to different concepts. Perfect graphs are, for instance, precisely those graphs G where the stable set polytope STAB(G) coincides with the fractional stable set polytope QSTAB(G). For all imperfect graphs G it holds that STAB(G). QSTAB(G). It is, therefore, natural to use the difference between the two polytopes in order to decide how far an imperfect graph is away from being perfect. We discuss three different concepts, involving the facet set of STAB(G), the disjunctive index of QSTAB(G), and the dilation ratio of the two polytopes. Including only certain types of facets for STAB(G), we obtain graphs that are in some sense close to perfect graphs, for example minimally imperfect graphs, and certain other classes of so-called rank-perfect graphs. The imperfection ratio has been introduced by Gerke and Mc-Diarmid [12] as the dilation ratio of STAB(G) and QSTAB(G), whereas Aguilera et al. [1] suggest to take the disjunctive index of QSTAB(G) as the imperfection index of G. For both invariants there exist no general upper bounds, but there are bounds known for the imperfection ratio of several graph classes [7,12]. Outgoing from a graph-theoretical interpretation of the imperfection index, we prove that there exists no upper bound on the imperfection index for those graph classes with a known bounded imperfection ratio. Comparing the two invariants on those classes, it seems that the imperfection index measures imperfection much more roughly than the imperfection ratio; we, therefore, discuss possible directions for refinements.