Impact of residual stress on coronary plaque stress/strain calculations using optical coherence tomography image-based multi-layer models

Introduction

Mechanical stress and strain conditions play an important role in atherosclerosis plaque progression, remodeling and potential rupture and may be used in plaque vulnerability assessment for better clinical diagnosis and treatment decisions. Single layer plaque models without residual stress have been widely used due to unavailability of multi-layer image segmentation method and residual stress data. However, vessel layered structure and residual stress have large impact on stress/strain calculations and should be included in the models.

Methods

In this study, intravascular optical coherence tomography (OCT) data of coronary plaques from 10 patients were acquired and segmented to obtain the three-layer vessel structure using an in-house automatic segmentation algorithm. Multi- and single-layer 3D thin-slice biomechanical plaque models with and without residual stress were constructed to assess the impact of residual stress on stress/strain calculations.

Results

Our results showed that residual stress led to a more uniform stress distribution across the vessel wall, with considerable plaque stress/strain decrease on inner wall and increase on vessel out-wall. Multi-layer model with residual stress inclusion reduced inner wall maximum and mean plaque stresses by 38.57% and 59.70%, and increased out-wall maximum and mean plaque stresses by 572.84% and 432.03%.

Conclusion

These findings demonstrated the importance of multi-layer modeling with residual stress for more accurate plaque stress/strain calculations, which will have great impact in plaque cap stress calculation and plaque rupture risk assessment. Further large-scale studies are needed to validate our findings.

[Effect of salvia miltiorrhiza combined with roxadustat on wound healing of full-thickness skin defects in diabetic rats and its mechanism]

Objective: To explore the effect of salvia miltiorrhiza combined with roxadustat on wound healing of full-thickness skin defects in diabetic rats and its mechanism. Methods: This study was an experimental study. Twenty male 8-week-old Sprague-Dawley rats were used to successfully establish diabetic model, then full-thickness skin defect wounds on their backs were made. The rats were divided into normal saline group, roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group according to the random number table, with 5 rats in each group. Immediately after injury, the rats in normal saline group were given 5 mL normal saline by gavage, the rats in roxadustat alone group were given 1.5 mg/mL roxadustat suspension by gavage at 25 mg/kg, the rats in salvia miltiorrhiza alone group were given 18 mg/mL salvia miltiorrhiza suspension by gavage at 300 mg/kg, and the rats in roxadustat+salvia miltiorrhiza group were given 19.5 mg/mL roxadustat and salvia miltiorrhiza suspension at roxadustat 25 mg/kg and salvia miltiorrhiza 300 mg/kg. All were administered once a day for 2 weeks. The wounds at 0 (immediately), 4, 8, and 12 d after injury were observed, and the wound healing rates at 4, 8, and 12 d after injury were calculated (n=5). At 14 d after injury, abdominal aortic blood was collected, and hemoglobin, red cell count, and white blood cell count were detected (n=5). The wound tissue was collected for hematoxylin-eosin staining to observe inflammatory infiltration, skin tissue structure, and neovascularization, for Masson staining to observe the proportion of collagen fiber (n=3), for Western blotting to detect the protein expression levels of vascular endothelial growth factor (VEGF), CD31, interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and IL-1β (n=3), and for immunohistochemical staining to determine the protein expression levels of epidermal growth factor receptor (EGFR), hypoxia-inducible factor 1α (HIF-1α), and proliferating cell nuclear antigen (PCNA), with sample number of 3. Results: From 0 to 12 d after injury, the wound areas of rats in 4 groups were gradually decreased. At 4 d after injury, the wound healing rates of rats in salvia miltiorrhiza alone group and roxadustat+salvia miltiorrhiza group were significantly higher than those in normal saline group and roxadustat alone group (P<0.05). At 8 d after injury, the wound healing rates of rats in roxadustat alone group and salvia miltiorrhiza alone group were significantly higher than the rate in normal saline group (P<0.05), and the wound healing rate of rats in roxadustat+salvia miltiorrhiza group was significantly higher than the rates in the other 3 groups (with P values all <0.05). At 12 d after injury, the wound healing rates of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were significantly higher than the rate in normal saline group (P<0.05). At 14 d after injury, there were no statistically significant differences in the hemoglobin or red blood cell count of rats in 4 groups (P<0.05). The white blood cell count of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were respectively (24.3±1.2)×109/L, (26.3±2.4)×109/L, and (15.0±0.7)×109/L, which were significantly lower than (33.8±2.7)×109/L in normal saline group (P<0.05); the white blood cell count of rats in roxadustat+salvia miltiorrhiza group was significantly lower than that in roxadustat alone group and salvia miltiorrhiza alone group (with P values both <0.05). At 14 d after injury, a large number of inflammatory cell infiltration, disordered skin tissue structure, and few new blood vessels were observed in the wounds of rats in normal saline group; while a small amount of inflammatory cell infiltration, tight skin tissue structure, and rich neovascularization were observed in the wounds of rats in the other 3 groups. There were no statistically significant differences in the proportion of collagen fiber of wounds in rats among the 4 groups (P>0.05). At 14 d after injury, the protein expression levels of VEGF and CD31 in the wound tissue of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were significantly higher than those in normal saline group (P<0.05), the protein expression level of CD31 in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly higher than the levels in roxadustat alone group and salvia miltiorrhiza alone group (with P values both <0.05). At 14 d after injury, the protein expression levels of IL-6, TNF-α, and IL-1β in the wound tissue of rats in roxadustat alone group, salvia miltiorrhiza alone group, and roxadustat+salvia miltiorrhiza group were significantly lower than those in normal saline group (P<0.05); the protein expression levels of IL-6 and IL-1β in the wound tissue of rats in roxadustat+salvia miltiorrhiza group were significantly lower than those in roxadustat alone group and salvia miltiorrhiza alone group (P<0.05); the protein expression level of TNF-α in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly lower than that in salvia miltiorrhiza alone group (P<0.05). At 14 d after injury, the protein expression level of EGFR in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly higher than the levels in the other 3 groups (with P values all <0.05); the protein expression levels of HIF-1α in the wound tissue of rats in roxadustat alone group and roxadustat+salvia miltiorrhiza group were significantly higher than the level in normal saline group (P<0.05), and the protein expression level of HIF-1α in the wound tissue of rats in roxadustat+salvia miltiorrhiza group was significantly higher than that in salvia miltiorrhiza alone group (P<0.05); there were no statistically significant differences in the protein expression level of PCNA in the wound tissue of rats in 4 groups (P>0.05). Conclusions: Roxadustat combined with salvia miltiorrhiza can promote the wound healing of full-thickness skin defects in diabetic rats by promoting blood vessel regeneration and reducing inflammatory response.

The clinical applications of D-type parastomal hernia repair surgery

OBJECTIVE

This study investigated the use of a modified laparoscopic repair of paraostomy hernia technique, called "D-Type parastomal hernia repair surgery" which combines abdominal wall and extraperitoneal stoma reconstruction, in patients with parastomal hernia (PSH) following colorectal stoma surgery. The aim was to determine whether D-type parastomal hernia repair surgery is a promising surgical approach compared to the traditional laparoscopic repair technique (Sugarbaker method) for patients with PSH.

METHODS

PSH patients were selected and retrospectively divided into two groups: the study group underwent D-type parastomal hernia repair, while the control group underwent laparoscopic Sugarbaker repair. Clinical data from both groups were analyzed.

RESULT

Compared to control group (n = 68), the study group undergoing D-type stoma lateral hernia repair had significant increase in total operative time (98.82 ± 12.37 min vs 124.61 ± 34.99 min, p < 0.001). The study group also showed better postoperative stoma bowel function scores in sensory ability, frequency of bowel movements, and clothing cleanliness without a stoma bag (p = 0.037, 0.001, 0.002). The treatment cost was significantly higher in the control group (3899.97 ± 260.00$ vs 3215.91 ± 230.03$, p < 0.001). The postoperative recurrence rate in the control group was 26.4%, while in the study group, it was 4.3%, with a significant statistical difference (p = 0.024). In terms of long-term postoperative complications, the study group had an overall lower incidence compared to the control group (p = 0.035). Other parameters showed no significant differences between the two groups.

CONCLUSION

The study suggests that D-type parastomal hernia repair surgery is a safe and feasible procedure. Compared to traditional surgery, it can reduce the recurrence of lateral hernia, improve postoperative stoma bowel function, and save medical resources.

Biomechanical characterization of normal and pathological human ascending aortic tissues via biaxial testing Experiment, constitutive modeling and finite element analysis

BACKGROUND

Aortic dissection and atherosclerosis are two common pathological conditions affecting the aorta. Aortic biomechanics are believed to be closely associated with the pathological development of these diseases. However, the biomechanical environment that predisposes the aortic wall to these pathological conditions remains unclear.

METHODS

Sixteen ascending aortic specimens were harvested from 16 human subjects and further categorized into three groups according to their disease states: aortic dissection group, aortic dissection with accompanied atherosclerosis group and healthy group. Experimental stress-strain data from biaxial tensile testing were used to fit the anisotropic Mooney-Rivlin model to determine material parameters. Computed tomography images or transesophageal echocardiography images were collected to construct computational models to simulate the stress/strain distributions in aortas at the pre-dissection state. Statistical analyses were performed to identify the biomechanical factors to distinguish three groups of aortic tissues.

RESULTS

Material parameters of anisotropic Mooney-Rivlin model were fitted with average R2 value 0.9749. The aortic diameter showed no significant difference among three groups. Changes of maximum and average stress values from minimum pressure to maximum pressure (△MaxStress and △AveStress) had significantly difference between dissection group and dissection with accompanied atherosclerosis group (p = 0.0201 and 0.0102). Changes of maximum and average strain values from minimum pressure to maximum pressure (△MaxStrain and △AveStrain) from dissection group were significant different from healthy group (p = 0.0171 and 0.0281).

CONCLUSION

Changes of stress and strain values during the cardiac cycle are good biomechanical factors for predicting potential aortic dissection and aortic dissection accompanied with atherosclerosis.

Evaluating the Use of SGRT and Abdominal Compression Device for Improved Patient Positioning in Liver Cancer Radiotherapy

PURPOSE/OBJECTIVE(S)

To mitigate tumor displacement caused by respiratory movement and to enhance positioning accuracy in liver cancer patients during radiotherapy, abdominal compression fixation devices are commonly employed. However, the efficacy of using surface guided radiotherapy (SGRT) to further improve patient setup accuracy in combination with abdominal compression has not been fully established. Hence, we aimed to investigate this in our study.

MATERIALS/METHODS

In this study, we analyzed data from 11 patients with liver cancer. The patients were positioned using isocentric skin markers and the abdominal compression fixture was placed on an accurate scale reading based on the records from CT simulation. A cone-beam CT (CBCT) scan was performed to assess setup errors. These setup errors represent data for the control group - Skin marker group. The patients were then adjusted to the correct treatment position based on CBCT correction and the SGRT system was activated for monitoring. Care was taken for the region of interest drawn to avoid the abdominal compression device for all patients. The reference surface used for monitoring was the captured VRT surface rather than DICOM. The six degrees of freedom values detected by the SGRT system were recorded, representing data for the test group - SGRT group. Both sets of data were analyzed using statistical software. The errors were presented as median (interquartile range) and the differences between the two groups were tested using paired Wilcoxon rank sum test, with P < 0.05 considered as significant.

RESULTS

A total of 60 CBCT images were analyzed, the median values and interquartile ranges are presented in the Table. The results showed that the accuracy of the SGRT group in the x and y directions was significantly better than the skin marker group (P < 0.05). The median values for the x (transverse) direction were 0.25(0.09-0.43) cm and 0.09(0.05-0.19) cm for the skin marker and SGRT groups, respectively. The median values for the y (longitudinal) direction were 0.54 (0.29-0.79) cm and 0.14 (0.07-0.24) cm for the skin marker and SGRT groups, respectively. The results for the z (vertical) direction, Rz (rotation), Ry (roll) and Rx (pitch) rotation directions were also analyzed similarly.

CONCLUSION

The findings of this study suggest that compared to skin markers, SGRT can improve the accuracy of patient positioning in liver cancer radiotherapy with abdominal compression, potentially reducing unnecessary radiation exposure from CBCT imaging due to inaccurate positioning. Further multicenter prospective clinical trials are required to confirm these results.

Impact of Right Ventricular Surface Area-to-Volume Ratio on Ventricular Remodeling After Pulmonary Valve Replacement

Optimal reverse remodeling of the right ventricle (RV), a sentinel goal of pulmonary valve replacement (PVR) in patients with repaired tetralogy of Fallot, is not fully predicted by volume-based pre-PVR parameters. Our objectives were to characterize novel geometric RV parameters in patients receiving PVR and in controls, and to identify associations between these parameters and chamber remodeling post-PVR. Secondary analysis was performed on cardiac magnetic resonance (CMR) data from 60 patients enrolled in a randomized trial of PVR with and without surgical RV remodeling. 20 healthy age-matched subjects served as controls. The primary outcome was optimal post-PVR RV remodeling (end-diastolic volume index (EDVi) ≤ 114 ml/m2 and ejection fraction (EF) ≥ 48%) vs. suboptimal remodeling (EDVi ≥ 120 ml/m2 and EF ≤ 45%). RV geometry was markedly different at baseline in PVR patients compared with controls, with lower systolic surface area-to-volume ratio (SAVR) (1.16 ± 0.26 vs.1.44 ± 0.21 cm2/mL, p < 0.001) and lower systolic circumferential curvature (0.87 ± 0.27 vs. 1.07 ± 0.30 cm- 1, p = 0.007) but similar longitudinal curvature. In the PVR cohort, higher systolic SAVR was associated with higher RVEF both pre- and post-PVR (p < 0.001). Among PVR patients, 15 had optimal and 19 had suboptimal remodeling post-PVR. Multivariable modeling showed that among the geometric parameters, higher systolic SAVR (OR 1.68 per 0.1 cm2/mL increase; p = 0.049) and shorter systolic RV long-axis length (OR 0.92 per 0.1 cm increase; p = 0.035) were independently associated with optimal remodeling. Compared with controls, PVR patients have lower SAVR and lower circumferential but not longitudinal curvature. Higher pre-PVR systolic SAVR is associated with optimal remodeling post-PVR.

Comparison of multilayer and single-layer coronary plaque models on stress/strain calculations based on optical coherence tomography images

Mechanical stress and strain conditions are closely related to atherosclerotic plaque progression and rupture and have been under intensive investigations in recent years. It is well known that arteries have a three-layer structure: intima, media and adventitia. However, in vivo image-based multilayer plaque models are not available in the current literature due to lack of multilayer image segmentation data. A multilayer segmentation and repairing technique was introduced to segment coronary plaque optical coherence tomography (OCT) image to obtain its three-layer vessel structure. A total of 200 OCT slices from 20 patients (13 male; 7 female) were used to construct multilayer and single-layer 3D thin-slice models to calculate plaque stress and strain and compare model differences. Our results indicated that the average maximum plaque stress values of 20 patients from multilayer and single-layer models were 385.13 ± 110.09 kPa and 270.91 ± 95.86 kPa, respectively. The relative difference was 42.2%, with single-layer stress serving as the base value. The average mean plaque stress values from multilayer and single-layer models were 129.59 ± 32.77 kPa and 93.27 ± 18.20 kPa, respectively, with a relative difference of 38.9%. The maximum and mean plaque strain values obtained from the multilayer models were 11.6% and 19.0% higher than those from the single-layer models. Similarly, the maximum and mean cap strains showed increases of 9.6% and 12.9% over those from the single-layer models. These findings suggest that use of multilayer models could improve plaque stress and strain calculation accuracy and may have large impact on plaque progression and vulnerability investigation and potential clinical applications. Further large-scale studies are needed to validate our findings.

Postoperative pulmonary complications in older patients undergoing elective surgery with a supraglottic airway device or tracheal intubation

The two most commonly used airway management techniques during general anaesthesia are supraglottic airway devices and tracheal tubes. In older patients undergoing elective non-cardiothoracic surgery under general anaesthesia with positive pressure ventilation, we hypothesised that a composite measure of in-hospital postoperative pulmonary complications would be less frequent when a supraglottic airway device was used compared with a tracheal tube. We studied patients aged ≥ 70 years in 17 clinical centres. Patients were allocated randomly to airway management with a supraglottic airway device or a tracheal tube. Between August 2016 and April 2020, 2900 patients were studied, of whom 2751 were included in the primary analysis (1387 with supraglottic airway device and 1364 with a tracheal tube). Pre-operatively, 2431 (88.4%) patients were estimated to have a postoperative pulmonary complication risk index of 1-2. Postoperative pulmonary complications, mostly coughing, occurred in 270 of 1387 patients (19.5%) allocated to a supraglottic airway device and 342 of 1364 patients (25.1%) assigned to a tracheal tube (absolute difference -5.6% (95%CI -8.7 to -2.5), risk ratio 0.78 (95%CI 0.67-0.89); p < 0.001). Among otherwise healthy older patients undergoing elective surgery under general anaesthesia with intra-operative positive pressure ventilation of their lungs, there were fewer postoperative pulmonary complications when the airway was managed with a supraglottic airway device compared with a tracheal tube.

A new approach of using organ-on-a-chip and fluid-structure interaction modeling to investigate biomechanical characteristics in tissue-engineered blood vessels

The tissue-engineered blood vessel (TEBV) has been developed and used in cardiovascular disease modeling, preclinical drug screening, and for replacement of native diseased arteries. Increasing attention has been paid to biomechanical cues in TEBV and other tissue-engineered organs to better recapitulate the functional properties of the native organs. Currently, computational fluid dynamics models were employed to reveal the hydrodynamics in TEBV-on-a-chip. However, the biomechanical wall stress/strain conditions in the TEBV wall have never been investigated. In this paper, a straight cylindrical TEBV was placed into a polydimethylsiloxane-made microfluidic device to construct the TEBV-on-a-chip. The chip was then perfused with cell culture media flow driven by a peristaltic pump. A three-dimensional fluid-structure interaction (FSI) model was generated to simulate the biomechanical conditions in TEBV and mimic both the dynamic TEBV movement and pulsatile fluid flow. The material stiffness of the TEBV wall was determined by uniaxial tensile testing, while the viscosity of cell culture media was measured using a rheometer. Comparison analysis between the perfusion experiment and FSI model results showed that the average relative error in diameter expansion of TEBV from both approaches was 10.0% in one period. For fluid flow, the average flow velocity over a period was 2.52 cm/s from the FSI model, 10.5% higher than the average velocity of the observed cell clusters (2.28 mm/s) in the experiment. These results demonstrated the facility to apply the FSI modeling approach in TEBV to obtain more comprehensive biomechanical results for investigating mechanical mechanisms of cardiovascular disease development.

[A prospective study on application of human umbilical cord mesenchymal stem cells combined with autologous Meek microskin transplantation in patients with extensive burns]

Objective: To investigate the effects of human umbilical cord mesenchymal stem cells (hUCMSCs) combined with autologous Meek microskin transplantation on patients with extensive burns. Methods: The prospective self-controlled study was conducted. From May 2019 to June 2022, 16 patients with extensive burns admitted to the 990th Hospital of PLA Joint Logistics Support Force met the inclusion criteria, while 3 patients were excluded according to the exclusion criteria, and 13 patients were finally selected, including 10 males and 3 females, aged 24-61 (42±13) years. A total of 20 trial areas (40 wounds, with area of 10 cm×10 cm in each wound) were selected. Two adjacent wounds in each trial area were divided into hUCMSC+gel group applied with hyaluronic acid gel containing hUCMSCs and gel only group applied with hyaluronic acid gel only according to the random number table, with 20 wounds in each group. Afterwards the wounds in two groups were transplanted with autologous Meek microskin grafts with an extension ratio of 1∶6. In 2, 3, and 4 weeks post operation, the wound healing was observed, the wound healing rate was calculated, and the wound healing time was recorded. The specimen of wound secretion was collected for microorganism culture if there was purulent secretion on the wound post operation. In 3, 6, and 12 months post operation, the scar hyperplasia in wound was assessed using the Vancouver scar scale (VSS). In 3 months post operation, the wound tissue was collected for hematoxylin-eosin (HE) staining to observe the morphological changes and for immunohistochemical staining to observe the positive expressions of Ki67 and vimentin and to count the number of positive cells. Data were statistically analyzed with paired samples t test and Bonferronni correction. Results: In 2, 3, and 4 weeks post operation, the wound healing rates in hUCMSC+gel group were (80±11)%, (84±12)%, and (92±9)%, respectively, which were significantly higher than (67±18)%, (74±21)%, and (84±16)% in gel only group (with t values of 4.01, 3.52, and 3.66, respectively, P<0.05). The wound healing time in hUCMSC+gel group was (31±11) d, which was significantly shorter than (36±13) d in gel only group (t=-3.68, P<0.05). The microbiological culture of the postoperative wound secretion specimens from the adjacent wounds in 2 groups was identical, with negative results in 4 trial areas and positive results in 16 trial areas. In 3, 6, and 12 months post operation, the VSS scores of wounds in gel only group were 7.8±1.9, 6.7±2.1, and 5.4±1.6, which were significantly higher than 6.8±1.8, 5.6±1.6, and 4.0±1.4 in hUCMSC+gel group, respectively (with t values of -4.79, -4.37, and -5.47, respectively, P<0.05). In 3 months post operation, HE staining showed an increase in epidermal layer thickness and epidermal crest in wound in hUCMSC+gel group compared with those in gel only group, and immunohistochemical staining showed a significant increase in the number of Ki67 positive cells in wound in hUCMSC+gel group compared with those in gel only group (t=4.39, P<0.05), with no statistically significant difference in the number of vimentin positive cells in wound between the 2 groups (P>0.05). Conclusions: The application of hyaluronic acid gel containing hUCMSCs to the wound is simple to perform and is therefore a preferable route. Topical application of hUCMSCs can promote healing of the autologous Meek microskin grafted area in patients with extensive burns, shorten wound healing time, and alleviate scar hyperplasia. The above effects may be related to the increased epidermal thickness and epidermal crest, and active cell proliferation.

Quantification of patient-specific coronary material properties and their correlations with plaque morphological characteristics: An in vivo IVUS study

BACKGROUND

A method using in vivo Cine IVUS and VH-IVUS data has been proposed to quantify material properties of coronary plaques. However, correlations between plaque morphological characteristics and mechanical properties have not been studied in vivo.

METHOD

In vivo Cine IVUS and VH-IVUS data were acquired at 32 plaque cross-sections from 19 patients. Six morphological factors were extracted for each plaque. These samples were categorized into healthy vessel, fibrous plaque, lipid-rich plaque and calcified plaque for comparisons. Three-dimensional thin-slice models were constructed using VH-IVUS data to quantify in vivo plaque material properties following a finite element updating approach by matching Cine IVUS data. Effective Young's moduli were calculated to represent plaque stiffness for easy comparison. Spearman's rank correlation analysis was performed to identify correlations between plaque stiffness and morphological factor. Kruskal-Wallis test with Bonferroni correction was used to determine whether significant differences in plaque stiffness exist among four plaque groups.

RESULT

Our results show that lumen circumference change has a significantly negative correlation with plaque stiffness (r = -0.7807, p = 0.0001). Plaque burden and calcification percent also had significant positive correlations with plaque stiffness (r = 0.5105, p < 0.0272 and r = 0.5312, p < 0.0193) respectively. Among the four categorized groups, calcified plaques had highest stiffness while healthy segments had the lowest.

CONCLUSION

There is a close link between plaque morphological characteristics and mechanical properties in vivo. Plaque stiffness tends to be higher as coronary atherosclerosis advances, indicating the potential to assess plaque mechanical properties in vivo based on plaque compositions.

Combining IVUS + OCT Data, Biomechanical Models and Machine Learning Method for Accurate Coronary Plaque Morphology Quantification and Cap Thickness and Stress/Strain Index Predictions

Assessment and prediction of vulnerable plaque progression and rupture risk are of utmost importance for diagnosis, management and treatment of cardiovascular diseases and possible prevention of acute cardiovascular events such as heart attack and stroke. However, accurate assessment of plaque vulnerability assessment and prediction of its future changes require accurate plaque cap thickness, tissue component and structure quantifications and mechanical stress/strain calculations. Multi-modality intravascular ultrasound (IVUS), optical coherence tomography (OCT) and angiography image data with follow-up were acquired from ten patients to obtain accurate and reliable plaque morphology for model construction. Three-dimensional thin-slice finite element models were constructed for 228 matched IVUS + OCT slices to obtain plaque stress/strain data for analysis. Quantitative plaque cap thickness and stress/strain indices were introduced as substitute quantitative plaque vulnerability indices (PVIs) and a machine learning method (random forest) was employed to predict PVI changes with actual patient IVUS + OCT follow-up data as the gold standard. Our prediction results showed that optimal prediction accuracies for changes in cap-PVI (C-PVI), mean cap stress PVI (meanS-PVI) and mean cap strain PVI (meanSn-PVI) were 90.3% (AUC = 0.877), 85.6% (AUC = 0.867) and 83.3% (AUC = 0.809), respectively. The improvements in prediction accuracy by the best combination predictor over the best single predictor were 6.6% for C-PVI, 10.0% for mean S-PVI and 8.0% for mean Sn-PVI. Our results demonstrated the potential using multi-modality IVUS + OCT image to accurately and efficiently predict plaque cap thickness and stress/strain index changes. Combining mechanical and morphological predictors may lead to better prediction accuracies.

Food Insecurity and Hearing Loss Are Interrelated: A Cross-Sectional Population-Based Study

OBJECTIVES

We aimed to assess whether objectively measured hearing loss and self-perceived hearing handicap in adults are independently associated with food insecurity, and vice versa.

DESIGN

Cross-sectional population-based study.

POPULATION

2,500 participants aged 50+ years from the Blue Mountains Hearing Study, with both complete pure-tone audiometry data and information on food security status.

MEASUREMENTS

The pure-tone average of frequencies 0.5, 1.0, 2.0 and 4.0 kHz (PTA0.5-4KHz) >25 dB HL in the better ear, established the presence of hearing loss. Self-perceived hearing handicap was assessed by administering the Hearing Handicap Inventory for Elderly Screening (HHIE-S total scores of ≥8 indicates hearing handicap). A 12-item food security survey was administered, comprising statements related to individual and household food situations.

RESULTS

Food insecurity was reported by 12.8% of study participants. After adjusting for all potential confounders, any self-perceived hearing handicap significantly increased the likelihood of participants reporting food insecurity by 94% (p<0.0001). Participants reporting any, mild or severe self-perceived hearing handicap had around 2-fold greater odds of experiencing food insecurity. Objectively measured hearing loss did not significantly influence the food security status of study participants. Conversely, food insecurity was significantly associated with both objectively measured hearing loss and self-perceived hearing handicap: multivariate-adjusted OR 1.37 (95% CI 1.01-1.88) and OR 1.83 (95% CI 1.40-2.39), respectively.

CONCLUSIONS

Food insecurity was an important social determinant of hearing health among community-dwelling adults. Conversely, participants with a significant self-perceived hearing handicap were more likely to experience food insecurity. These findings add to our understanding of the substantial public health impact of both food insecurity and hearing loss and may highlight areas for future intervention.

Human Coronary Plaque Optical Coherence Tomography Image Repairing, Multilayer Segmentation and Impact on Plaque Stress/Strain Calculations

Coronary vessel layer structure may have a considerable impact on plaque stress/strain calculations. Most current plaque models use single-layer vessel structures due to the lack of available multilayer segmentation techniques. In this paper, an automatic multilayer segmentation and repair method was developed to segment coronary optical coherence tomography (OCT) images to obtain multilayer vessel geometries for biomechanical model construction. Intravascular OCT data were acquired from six patients (one male; mean age: 70.0) using a protocol approved by the local institutional review board with informed consent obtained. A total of 436 OCT slices were selected in this study. Manually segmented data were used as the gold standard for method development and validation. The edge detection method and cubic spline surface fitting were applied to detect and repair the internal elastic membrane (IEM), external elastic membrane (EEM) and adventitia-periadventitia interface (ADV). The mean errors of automatic contours compared to manually segmented contours were 1.40%, 4.34% and 6.97%, respectively. The single-layer mean plaque stress value from lumen was 117.91 kPa, 10.79% lower than that from three-layer models (132.33 kPa). On the adventitia, the single-layer mean plaque stress value was 50.46 kPa, 156.28% higher than that from three-layer models (19.74 kPa). The proposed segmentation technique may have wide applications in vulnerable plaque research.

[The analysis of long-term prognostic factors after laparoscopic liver resection for intrahepatic cholangiocarcinoma and establishment of survival Nomogram model]

Objective: To establish a survival prediction model based on the independent prognostic factors of long-term prognosis after laparoscopic liver resection(LLR) for intrahepatic cholangiocarcinoma(ICC). Methods: The clinical and pathological data of 351 consecutive patients with ICC who received radical LLR in 13 Chinese medical centers from August 2010 to May 2021 were collected retrospectively. There were 190 males and 161 females,aged(M(IQR)) 61(14)years(range:23 to 93 years). The total cohort was randomly divided into a training dataset(264 cases) and a validation dataset(87 cases). The patients were followed up by outpatient service or telephone,and the deadline for follow-up was October 2021. Based on the training dataset,the multivariate Cox proportional hazards regression model was used to screen the independent influencing factors of long-term prognosis to construct a Nomogram model. The Nomogram model's discrimination,calibration,and clinical benefit were evaluated through internal and external validation,and an assessment of the overall value of two groups was made through the use of a receiver operating characteristic(ROC) curve. Results: There was no significant difference in clinical and pathological characteristics and long-term survival results between the training and validation datasets(all P>0.05). The multivariate Cox analysis showed that CA19-9,CA125,conversion to laparotomy during laparoscopic surgery,and lymph node metastasis were independent prognostic factors for ICC patients after LLR(all P<0.05). The survival Nomogram was established based on the independent prognostic factors obtained from the above screening. The ROC curve showed that the area under the curve of 1, 3 and 5-year overall survival rates of patients in the training dataset were 0.794(95%CI:0.721 to 0.867),0.728(95%CI:0.618 to 0.839) and 0.799(95%CI:0.670 to 0.928),and those in the validation dataset were 0.787(95%CI:0.660 to 0.915),0.831(95%CI:0.678 to 0.983) and 0.810(95%CI:0.639 to 0.982). Internal and external validation proved that the model exhibited a certain discrimination,calibration,and clinical applicability. Conclusion: The survival Nomogram model based on the independent influencing factors of long-term prognosis after LLR for ICC(including CA19-9,CA125,conversion to laparotomy during laparoscopic surgery,and lymph node metastasis) exhibites a certain differentiation,calibration,and clinical practicability.

[Analysis of pathogenic bacteria in cirrhotic patients complicated with bacterial infection in a tertiary hospital in Xinjiang]

Objective: To understand the species, distribution, and extent of drug resistance of pathogenic bacteria in patients with liver cirrhosis combined with bacterial infection in a tertiary hospital in Xinjiang. Methods: 1 271 cases with liver cirrhosis combined with infection were analyzed retrospectively for pathogenic bacterial species and drug resistance condition in different bacterial strain. Results: Among the 1 271 cases with liver cirrhosis, 480 were combined with infection, and the infection rate was 37.8%. The majority of infected patients had decompensated cirrhosis (438 cases). Peritoneum (327 cases, 60.8%) was the common infection site, followed by lungs (16.9%). 343 strains of pathogens were isolated from 480 infected cases, of which 289 strains were among the top 10 common distinct bacteria, accounting for 76.5% and 23.5% of Gram-negative and positive bacteria. The first top three strains were Escherichia coli. (33.2%), Klebsiella pneumoniae (11.4%), and Enterococcus faecium (11.1%), and there were differences in the drug resistance rates of each strain. Conclusion: In a tertiary hospital in Xinjiang, patients with decompensated cirrhosis have a high rate of bacterial infection. The pathogenic bacteria are diverse, mainly Gram-negative bacteria; however, the infection rate of Gram-positive bacteria such as Enterococcus is gradually increasing. Additionally, according to the bacterial properties, they are divided into four categories: Enterobacter, Enterococcus, glucose non-fermenting bacteria and Staphylococcus, and it is found that even the same species of bacteria have different drug resistance rates.

[Two-dimensional equivalent mechanical modeling and finite element analysis of normal female pelvic floor system]

Objective: To construct the geometric model of the pelvic floor by a two-dimensional equivalent mechanics method, and to explore the effect of the shape and position of pelvic floor organs and tissues on the biomechanical properties of the pelvic floor under different abdominal pressure. Methods: A 28-year-old healthy and symmetrical married infertile female volunteer was included. The pelvic floor tissue was scanned in the supine position using a 3.0T magnetic resonance scanner (Philips Company, Holland). Based on the method of magnetic resonance imaging (MRI) two-dimensional parameter measurement and computer aided design, the geometric model and finite element model of the female pelvic floor were established, and the biomechanical characteristics of the pelvic floor support system under different abdominal pressure were analyzed. Results: In this study, four different working conditions of the pelvic floor force were simulated under 60, 99, 168, and 208 cmH₂O (1 cmH₂O=0.098 kPa) abdominal pressure loads. The trend was as follows: under the abdominal pressure load, the retrograde flexion of the uterus occurred, the cervical, the middle and upper vaginal segment and the levator anus muscle had the characteristic change of mechanical axial direction pointing to the sacrum and coccyx, and the deformation of the levator anus muscle in the horizontal direction was greater than that in the vertical direction. With the increase of the abdominal pressure, the maximum stress values of the pelvic floor whole system of healthy subjects under four different working conditions were 0.194 3, 0.389 6, 0.557 1, and 0.627 5 MPa, respectively, and the maximum displacement values were 10, 14, 21 and 25 mm, respectively. The maximum stress values of the cervical and vaginal middle and upper segment were 0.111 7, 0.161 8, 0.250 6, and 0.304 1 MPa, respectively, and the maximum displacement values were 3, 6, 9, and 11 mm, respectively. The maximum stress of the perineal body was 0.063 4, 0.119 6, 0.235 2, and 0.288 0 MPa, and the maximum displacement was 1, 2, 4, and 5 mm. The maximum stress values of the levator anus muscle were 0.194 3, 0.389 6, 0.557 1, and 0.627 5 MPa, and the maximum displacement values were 2, 4, 7, and 8 mm, respectively. The maximum stress and maximum displacement of pelvic organs increased with the increase of the abdominal pressure under different working conditions. The stress axial relationship of normal female pelvic floor was that the middle and upper segment of uterus and vagina mainly acted on the sacrococcyx and the levator anus muscle, and the lower vaginal segment acts on the perineal body. Conclusions: The two-dimensional equivalent mechanical modeling and finite element analysis of the female pelvic floor system can accurately reflect the biomechanical characteristics of the female pelvic floor, and the resultant stress direction of the pelvic organs points to the sacrum and coccyx. The sacrum and coccyx, levator anus and perineal body play important stress supporting roles in the pelvic floor system.

[Application values of right atrial volume, myocardial strain and strain rate in evaluating right atrial function in patients with essential hypertension with normal left ventricular ejection fraction]

Objective: To explore the application values of right atrial (RA) volume, myocardial strain and strain rate in evaluating right atrial functions in patients with essential hypertension (EHT) with normal left ventricular ejection fraction (LVEF). Methods: We retrospectively collected a total of 126 EHT patients with normal LVEF, including 66 males and 60 females, age from 18 to 83(48±15) years from the Affiliated Changzhou No.2 People's Hospital with Nanjing Medical University from March, 2018 to May, 2020. According to the left ventricular mass index, those patients were divided into without left ventricle hypertrophy (LVH) group (n=66) and LVH group (n=60), and 83 healthy volunteers were enrolled as control group, which including 42 males and 41 females, age from 14 to 88 (48±16) years. The total, passive and active RA emptying fraction (total RAEF, passive RAEF and active RAEF) were measured by using RA volumes method. The RA strain (S-reservoir, S-conduit, S-booster pump) and the strain rate (SR-reservoir, SR-conduit, SR-booster pump) were measured by two-dimensional speckle tracking echocardiography. Total RAEF, S-reservoir, and Sr-reservoir represented the reservoir function, while passive RAEF, S-conduit, and Sr-conduit represented the conduit function, and active RAEF, S-booster pump and Sr-booster pump represented the booster pump function, respectively. Than the values between the EHT patients and normal subjects, and the values among the EHT patients without LVH, EHT patients without LVH and normal subjects were compared. Results: The value of active RAEF was significantly lower in EHT patient than normal controls (40.1%±10.5% vs 45.4%±11.1%,P=0.001). There were significant differences among EHT patients without LVH, EHT patients with LVH and normal subjects in passive RAEF and active RAEF (passive RAEF: 40.2%±9.3% vs 36.4%±10.7% vs 36.5%±9.4%, P=0.038, active RAEF: 39.8%±10.6% vs 40.4%±10.4% vs 45.4%±11.1%, P=0.002). There were significant differences in S-reservoir, S-conduit, S-booster pump, SR-reservoir, SR-conduit and SR-booster pump between EHT patients and normal subjects [S-reservoir: 34.8%±13.7% vs 45.0%±13.3%, S-conduit: 18.3%±9.4% vs 26.5%±9.6%, S-booster pump: 16.4%±7.3% vs 18.6%±7.1%, SR-reservoir: (1.6±0.6)/s vs (2.0±0.6)/s, SR-conduit: (-1.2±0.5)/s vs (-1.6±0.6)/s, SR-booster pump: (-1.7±0.6)/s vs (-2.3±0.6)/s; all P<0.05]. The trend tests showed normal controls achieved the largest the absolute values of S-reservoir, S-conduit, SR-reservoir, SR-conduit, SR-booster pump, followed by EHT patients without LVH and EHT patients with LVH(all P<0.001). Conclusions: Using RA volume, myocardial strain and strain rate can detect the RA impaired reservoir, conduit, and the booster pump functions in EHT patients with normal LVEF, and the RA functions were damaged more significantly in EHT patients with LVH.

Predicting Coronary Stenosis Progression Using Plaque Fatigue From IVUS-Based Thin-Slice Models: A Machine Learning Random Forest Approach

Introduction: Coronary stenosis due to atherosclerosis restricts blood flow. Stenosis progression would lead to increased clinical risk such as heart attack. Although many risk factors were found to contribute to atherosclerosis progression, factors associated with fatigue is underemphasized. Our goal is to investigate the relationship between fatigue and stenosis progression based on in vivo intravascular ultrasound (IVUS) images and finite element models.

Methods: Baseline and follow-up in vivo IVUS and angiography data were acquired from seven patients using Institutional Review Board approved protocols with informed consent obtained. Three hundred and five paired slices at baseline and follow-up were matched and used for plaque modeling and analysis. IVUS-based thin-slice models were constructed to obtain the coronary biomechanics and stress/strain amplitudes (stress/strain variations in one cardiac cycle) were used as the measurement of fatigue. The change of lumen area (DLA) from baseline to follow-up were calculated to measure stenosis progression. Nineteen morphological and biomechanical factors were extracted from 305 slices at baseline. Correlation analyses of these factors with DLA were performed. Random forest (RF) method was used to fit morphological and biomechanical factors at baseline to predict stenosis progression during follow-up.

Results: Significant correlations were found between stenosis progression and maximum stress amplitude, average stress amplitude and average strain amplitude (p < 0.05). After factors selection implemented by random forest (RF) method, eight morphological and biomechanical factors were selected for classification prediction of stenosis progression. Using eight factors including fatigue, the overall classification accuracy, sensitivity and specificity of stenosis progression prediction with RF method were 83.61%, 86.25% and 80.69%, respectively.

Conclusion: Fatigue correlated positively with stenosis progression. Factors associated with fatigue could contribute to better prediction for atherosclerosis progression.

Bacterial driver-passenger model in biofilms: a new mechanism in the development of colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease of the intestinal epithelium and ranks the third largest diagnosed malignancy in the world. Many studies have shown that the high risk of CRC is believed to be related to the formation of biofilms. To prove causation, it will be significant to decipher which specific bacteria in biofilms initiate and maintain CRC and fully describe their underlying mechanisms. Here we introduce a bacterial driver-passenger model. This model added a novel and compelling angle to the role of microorganisms, putting more emphasis on the transformation of bacterial composition in biofilms which play different roles in the development of CRC. In this model, bacterial drivers can initiate the formation of CRC through genotoxicity, while bacterial passengers maintain the CRC process through metabolites. On the basis of these pathogens, we further turned our attention to strategies that can inhibit and eradicate these pathogenic biofilms, with the aim of finding new ways to hinder colorectal carcinogenesis.

Melanoma secretion of transforming growth factor-β2 leads to loss of epidermal AMBRA1 threatening epidermal integrity and facilitating tumour ulceration

BACKGROUND

For patients with early American Joint Committee on Cancer (AJCC)-stage melanoma the combined loss of the autophagy regulatory protein AMBRA1 and the terminal differentiation marker loricrin in the peritumoral epidermis is associated with a significantly increased risk of metastasis.

OBJECTIVES

The aim of the present study was to evaluate the potential contribution of melanoma paracrine transforming growth factor (TGF)-β signalling to the loss of AMBRA1 in the epidermis overlying the primary tumour and disruption of epidermal integrity.

METHODS

Immunohistochemistry was used to analyse AMBRA1 and TGF-β2 in a cohort of 109 AJCC all-stage melanomas, and TGF-β2 and claudin-1 in a cohort of 30 or 42 AJCC stage I melanomas, respectively, with known AMBRA1 and loricrin (AMLo) expression. Evidence of pre-ulceration was analysed in a cohort of 42 melanomas, with TGF-β2 signalling evaluated in primary keratinocytes.

RESULTS

Increased tumoral TGF-β2 was significantly associated with loss of peritumoral AMBRA1 (P < 0·05), ulceration (P < 0·001), AMLo high-risk status (P < 0·05) and metastasis (P < 0·01). TGF-β2 treatment of keratinocytes resulted in downregulation of AMBRA1, loricrin and claudin-1, while knockdown of AMBRA1 was associated with decreased expression of claudin-1 and increased proliferation of keratinocytes (P < 0·05). Importantly, we show loss of AMBRA1 in the peritumoral epidermis was associated with decreased claudin-1 expression (P < 0·05), parakeratosis (P < 0·01) and cleft formation in the dermoepidermal junction (P < 0·05).

CONCLUSIONS

Collectively, these data suggest a paracrine mechanism whereby TGF-β2 causes loss of AMBRA1 overlying high-risk AJCC early-stage melanomas and reduced epidermal integrity, thereby facilitating erosion of the epidermis and tumour ulceration.

Optimization of Left Ventricle Pace Maker Location Using Echo-Based Fluid-Structure Interaction Models

Introduction

Cardiac pacing has been an effective treatment in the management of patients with bradyarrhythmia and tachyarrhythmia. Different pacemaker location has different responses, and pacemaker effectiveness to each individual can also be different. A novel image-based ventricle animal modeling approach was proposed to optimize ventricular pacemaker site for better cardiac outcome.

Method

One health female adult pig (weight 42.5 kg) was used to make a pacing animal model with different ventricle pacing locations. Ventricle surface electric signal, blood pressure and echo image were acquired 15 min after the pacemaker was implanted. Echo-based left ventricle fluid-structure interaction models were constructed to perform ventricle function analysis and investigate impact of pacemaker location on cardiac outcome. With the measured electric signal map from the pig associated with the actual pacemaker site, electric potential conduction of myocardium was modeled by material stiffening and softening in our model, with stiffening simulating contraction and softening simulating relaxation. Ventricle model without pacemaker (NP model) and three ventricle models with the following pacemaker locations were simulated: right ventricular apex (RVA model), posterior interventricular septum (PIVS model) and right ventricular outflow tract (RVOT model). Since higher peak flow velocity, flow shear stress (FSS), ventricle stress and strain are linked to better cardiac function, those data were collected for model comparisons.

Results

At the peak of filling, velocity magnitude, FSS, stress and strain for RVOT and PIVS models were 13%, 45%, 18%, 13% and 5%, 30%, 10%, 5% higher than NP model, respectively. At the peak of ejection, velocity magnitude, FSS, stress and strain for RVOT and PIVS models were 50%, 44%, 54%, 59% and 23%, 36%, 39%, 53% higher than NP model, respectively. RVA model had lower velocity, FSS, stress and strain than NP model. RVOT model had higher peak flow velocity and stress/strain than PIVS model. It indicated RVOT pacemaker site may be the best location.

Conclusion

This preliminary study indicated that RVOT model had the best performance among the four models compared. This modeling approach could be used as “virtual surgery” to try various pacemaker locations and avoid risky and dangerous surgical experiments on real patients.

Image-based biomechanical modeling for coronary atherosclerotic plaque progression and vulnerability prediction

Atherosclerotic plaque progression and rupture play an important role in cardiovascular disease development and the final drastic events such as heart attack and stroke. Medical imaging and image-based computational modeling methods advanced considerably in recent years to quantify plaque morphology and biomechanical conditions and gain a better understanding of plaque evolution and rupture process. This article first briefly reviewed clinical imaging techniques for coronary thin-cap fibroatheroma (TCFA) plaques used in image-based computational modeling. This was followed by a summary of different types of biomechanical models for coronary plaques. Plaque progression and vulnerability prediction studies based on image-based computational modeling were reviewed and compared. Much progress has been made and a reasonable high prediction accuracy has been achieved. However, there are still some inconsistencies in existing literature on the impact of biomechanical and morphological factors on future plaque behavior, and it is very difficult to perform direct comparison analysis as differences like image modality, biomechanical factors selection, predictive models, and progression/vulnerability measures exist among these studies. Encouraging data and model sharing across the research community would partially resolve these differences, and possibly lead to clearer assertive conclusions. In vivo image-based computational modeling could be used as a powerful tool for quantitative assessment of coronary plaque vulnerability for potential clinical applications.

Hemodynamic Mimic Shear Stress for Platelet Membrane Nanobubbles Preparation and Integrin αIIbβ3 Conformation Regulation

Platelet (PLT) membrane biomimetic nanomaterials have become promising theranostic platforms due to their good biocompatibility and effectiveness. However, in order to achieve precise regulation of cell membrane components, novel controllable construction approaches need to be developed. Inspired by the interaction mechanism among platelet production, activation, and dynamic biomechanical signals in blood circulation, here a platelet nanobubbles (PNBs) with reassembled platelet membrane with ideal echogenicity was fabricated using an adjustable pressure-induced shear stress method. The results demonstrate that the high shear stress during PNBs fabrication led to the enrichment of platelet membrane lipid rafts and proteins, as well as their reassembly on the gas-liquid interface. More importantly, the conformation of platelet integrin α_IIbβ₃ was transformed into a shear stress-induced intermediate affinity state, which gives PNBs enhanced adhesion ability to the vascular endothelial injury. Taken together, these PNBs have great application potential in the specifically targeted ultrasound diagnosis of vascular endothelial injury.

Design, Synthesis, and Characterization of I-BET567, a Pan-Bromodomain and Extra Terminal (BET) Bromodomain Oral Candidate

Through regulation of the epigenome, the bromodomain and extra terminal (BET) family of proteins represent important therapeutic targets for the treatment of human disease. Through mimicking the endogenous N-acetyl-lysine group and disrupting the protein-protein interaction between histone tails and the bromodomain, several small molecule pan-BET inhibitors have progressed to oncology clinical trials. This work describes the medicinal chemistry strategy and execution to deliver an orally bioavailable tetrahydroquinoline (THQ) pan-BET candidate. Critical to the success of this endeavor was a potency agnostic analysis of a data set of 1999 THQ BET inhibitors within the GSK collection which enabled identification of appropriate lipophilicity space to deliver compounds with a higher probability of desired oral candidate quality properties. SAR knowledge was leveraged via Free-Wilson analysis within this design space to identify a small group of targets which ultimately delivered I-BET567 (27), a pan-BET candidate inhibitor that demonstrated efficacy in mouse models of oncology and inflammation.

Optical Coherence Tomography-Derived Changes in Plaque Structural Stress Over the Cardiac Cycle: A New Method for Plaque Biomechanical Assessment

Introduction: Cyclic plaque structural stress has been hypothesized as a mechanism for plaque fatigue and eventually plaque rupture. A novel approach to derive cyclic plaque stress in vivo from optical coherence tomography (OCT) is hereby developed. Materials and Methods: All intermediate lesions from a previous OCT study were enrolled. OCT cross-sections at representative positions within each lesion were selected for plaque stress analysis. Detailed plaque morphology, including plaque composition, lumen and internal elastic lamina contours, were automatically delineated. OCT-derived vessel and plaque morphology were included in a 2-dimensional finite element analysis, loaded with patient-specific intracoronary pressure tracing data, to calculate the changes in plaque structural stress (ΔPSS) on vessel wall over the cardiac cycle. Results: A total of 50 lesions from 41 vessels were analyzed. A significant ΔPSS gradient was observed across the plaque, being maximal at the proximal shoulder (45.7 [32.3, 78.6] kPa), intermediate at minimal lumen area (MLA) (39.0 [30.8, 69.1] kPa) and minimal at the distal shoulder (35.1 [28.2, 72.3] kPa; p = 0.046). The presence of lipidic plaques were observed in 82% of the diseased segments. Larger relative lumen deformation and ΔPSS were observed in diseased segments, compared with normal segments (percent diameter change: 8.2 ± 4.2% vs. 6.3 ± 2.3%, p = 0.04; ΔPSS: 59.3 ± 48.2 kPa vs. 27.5 ± 8.2 kPa, p < 0.001). ΔPSS was positively correlated with plaque burden (r = 0.37, p < 0.001) and negatively correlated with fibrous cap thickness (r = -0.25, p = 0.004). Conclusions: ΔPSS provides a feasible method for assessing plaque biomechanics in vivo from OCT images, consistent with previous biomechanical and clinical studies based on different methodologies. Larger ΔPSS at proximal shoulder and MLA indicates the critical sites for future biomechanical assessment.

Quantifying Patient-Specific in vivo Coronary Plaque Material Properties for Accurate Stress/Strain Calculations: An IVUS-Based Multi-Patient Study

Introduction: Mechanical forces are closely associated with plaque progression and rupture. Precise quantifications of biomechanical conditions using in vivo image-based computational models depend heavily on the accurate estimation of patient-specific plaque mechanical properties. Currently, mechanical experiments are commonly performed on ex vivo cardiovascular tissues to determine plaque material properties. Patient-specific in vivo coronary material properties are scarce in the existing literature.

Methods:In vivo Cine intravascular ultrasound and virtual histology intravascular ultrasound (IVUS) slices were acquired at 20 plaque sites from 13 patients. A three-dimensional thin-slice structure-only model was constructed for each slice to obtain patient-specific in vivo material parameter values following an iterative scheme. Effective Young's modulus (YM) was calculated to indicate plaque stiffness for easy comparison purposes. IVUS-based 3D thin-slice models using in vivo and ex vivo material properties were constructed to investigate their impacts on plaque wall stress/strain (PWS/PWSn) calculations.

Results: The average YM values in the axial and circumferential directions for the 20 plaque slices were 599.5 and 1,042.8 kPa, respectively, 36.1% lower than those from published ex vivo data. The YM values in the circumferential direction of the softest and stiffest plaques were 103.4 and 2,317.3 kPa, respectively. The relative difference of mean PWSn on lumen using the in vivo and ex vivo material properties could be as high as 431%, while the relative difference of mean PWS was much lower, about 3.07% on average.

Conclusion: There is a large inter-patient and intra-patient variability in the in vivo plaque material properties. In vivo material properties have a great impact on plaque stress/strain calculations. In vivo plaque material properties have a greater impact on strain calculations. Large-scale-patient studies are needed to further verify our findings.

[Causal graph model and its application in nutritional epidemiologic research]

Suboptimal diet is one of the most important controllable risk factors for non-communicable diseases. However, randomized controlled trials make it difficult to quantify the causal association between specific dietary factors and health outcomes. In recent years, the rapid development of causal inference has provided a robust theoretical and methodological tool for making full use of observational research data and producing high-quality nutritional epidemiologic research evidence. The causal graph model visualizes the complex causal relationship system by integrating a large amount of prior knowledge and provides a basic framework for identifying confounding and determining causal effect estimation strategies. Different analysis strategies such as adjusting confounders, instrumental variables, or mediation analysis can be created based on other causal graphs. This paper introduces the idea of the causal graph model and the characteristics of various analysis strategies and their application in nutritional epidemiology research, aiming to promote the application of the causal graph model in nutrition and provide references and suggestions for the follow-up research.

Using Optical Coherence Tomography and Intravascular Ultrasound Imaging to Quantify Coronary Plaque Cap Stress/Strain and Progression: A Follow-Up Study Using 3D Thin-Layer Models

Accurate plaque cap thickness quantification and cap stress/strain calculations are of fundamental importance for vulnerable plaque research. To overcome uncertainties due to intravascular ultrasound (IVUS) resolution limitation, IVUS and optical coherence tomography (OCT) coronary plaque image data were combined together to obtain accurate and reliable cap thickness data, stress/strain calculations, and reliable plaque progression predictions. IVUS, OCT, and angiography baseline and follow-up data were collected from nine patients (mean age: 69; m: 5) at Cardiovascular Research Foundation with informed consent obtained. IVUS and OCT slices were coregistered and merged to form IVUS + OCT (IO) slices. A total of 114 matched slices (IVUS and OCT, baseline and follow-up) were obtained, and 3D thin-layer models were constructed to obtain stress and strain values. A generalized linear mixed model (GLMM) and least squares support vector machine (LSSVM) method were used to predict cap thickness change using nine morphological and mechanical risk factors. Prediction accuracies by all combinations (511) of those predictors with both IVUS and IO data were compared to identify optimal predictor(s) with their best accuracies. For the nine patients, the average of minimum cap thickness from IVUS was 0.17 mm, which was 26.08% lower than that from IO data (average = 0.23 mm). Patient variations of the individual errors ranged from ‒58.11 to 20.37%. For maximum cap stress between IO and IVUS, patient variations of the individual errors ranged from ‒30.40 to 46.17%. Patient variations of the individual errors of maximum cap strain values ranged from ‒19.90 to 17.65%. For the GLMM method, the optimal combination predictor using IO data had AUC (area under the ROC curve) = 0.926 and highest accuracy = 90.8%, vs. AUC = 0.783 and accuracy = 74.6% using IVUS data. For the LSSVM method, the best combination predictor using IO data had AUC = 0.838 and accuracy = 75.7%, vs. AUC = 0.780 and accuracy = 69.6% using IVUS data. This preliminary study demonstrated improved plaque cap progression prediction accuracy using accurate cap thickness data from IO slices and the differences in cap thickness, stress/strain values, and prediction results between IVUS and IO data. Large-scale studies are needed to verify our findings.

A Novel Pulmonary Valve Replacement Surgery Strategy Using Contracting Band for Patients With Repaired Tetralogy of Fallot: An MRI-Based Multipatient Modeling Study

Patients with repaired Tetralogy of Fallot (ToF), a congenital heart defect which includes a ventricular septal defect and severe right ventricular outflow obstruction, account for the majority of cases with late-onset right ventricle (RV) failure. Current surgery procedures, including pulmonary valve replacement (PVR) with right ventricle remodeling, yield mixed results. PVR with active band insertion was hypothesized to be of clinical usage on improving RV function measured by ejection fraction (EF). In lieu of risky open-heart surgeries and experiments on animal and human, computational biomechanical models were adapted to study the impact of PVR with five band insertion options. Cardiac magnetic resonance (CMR) images were acquired from seven TOF patients before PVR surgery for model construction. For each patient, five different surgery plans combined with passive and active contraction band with contraction ratio of 20, 15, and 10% were studied. Those five plans include three single-band plans with different band locations; one plan with two bands, and one plan with three bands. Including the seven no-band models, 147 computational bi-ventricle models were constructed to simulate RV cardiac functions and identify optimal band plans. Patient variations with different band plans were investigated. Surgery plan with three active contraction bands and band active contraction ratio of 20% had the best performance on improving RV function. The mean ± SD RV ejection fraction value from the seven patients was 42.90 ± 5.68%, presenting a 4.19% absolute improvement or a 10.82% relative improvement, when compared with the baseline models (38.71 ± 5.73%, p = 0.016). The EF improvements from the seven patients varied from 2.87 to 6.01%. Surgical procedures using active contraction bands have great potential to improve RV function measured by ejection fraction for patients with repaired ToF. It is possible to have higher right ventricle ejection fraction improvement with more bands and higher band active contraction ratio. Our findings with computational models need to be further validated by animal experiments before clinical trial could become possible.

Optical Coherence Tomography-Based Patient-Specific Residual Multi-Thrombus Coronary Plaque Models With Fluid-Structure Interaction for Better Treatment Decisions: A Biomechanical Modeling Case Study

Intracoronary thrombus from plaque erosion could cause fatal acute coronary syndrome (ACS). A conservative antithrombotic therapy has been proposed to treat ACS patients in lieu of stenting. It is speculated that the residual thrombus after aspiration thrombectomy would influence the prognosis of this treatment. However, biomechanical mechanisms affecting intracoronary thrombus remodeling and clinical outcome remain largely unknown. in vivo optical coherence tomography (OCT) data of a coronary plaque with two residual thrombi after antithrombotic therapy were acquired from an ACS patient with consent obtained. Three OCT-based fluid-structure interaction (FSI) models with different thrombus volumes, fluid-only, and structure-only models were constructed to simulate and compare the biomechanical interplay among blood flow, residual thrombus, and vessel wall mimicking different clinical situations. Our results showed that residual thrombus would decrease coronary volumetric flow rate by 9.3%, but elevate wall shear stress (WSS) by 29.4% and 75.5% at thrombi 1 and 2, respectively. WSS variations in a cardiac cycle from structure-only model were 12.1% and 13.5% higher at the two thrombus surfaces than those from FSI model. Intracoronary thrombi were subjected to compressive forces indicated by negative thrombus stress. Tandem intracoronary thrombus might influence coronary hemodynamics and solid mechanics differently. Computational modeling could be used to quantify biomechanical conditions under which patients could receive patient-specific treatment plan with optimized outcome after antithrombotic therapy. More patient studies with follow-up data are needed to continue the investigation and better understand mechanisms governing thrombus remodeling process.

Predicting plaque vulnerability change using intravascular ultrasound + optical coherence tomography image-based fluid-structure interaction models and machine learning methods with patient follow-up data: a feasibility study

Background

Coronary plaque vulnerability prediction is difficult because plaque vulnerability is non-trivial to quantify, clinically available medical image modality is not enough to quantify thin cap thickness, prediction methods with high accuracies still need to be developed, and gold-standard data to validate vulnerability prediction are often not available. Patient follow-up intravascular ultrasound (IVUS), optical coherence tomography (OCT) and angiography data were acquired to construct 3D fluid–structure interaction (FSI) coronary models and four machine-learning methods were compared to identify optimal method to predict future plaque vulnerability.

Methods

Baseline and 10-month follow-up in vivo IVUS and OCT coronary plaque data were acquired from two arteries of one patient using IRB approved protocols with informed consent obtained. IVUS and OCT-based FSI models were constructed to obtain plaque wall stress/strain and wall shear stress. Forty-five slices were selected as machine learning sample database for vulnerability prediction study. Thirteen key morphological factors from IVUS and OCT images and biomechanical factors from FSI model were extracted from 45 slices at baseline for analysis. Lipid percentage index (LPI), cap thickness index (CTI) and morphological plaque vulnerability index (MPVI) were quantified to measure plaque vulnerability. Four machine learning methods (least square support vector machine, discriminant analysis, random forest and ensemble learning) were employed to predict the changes of three indices using all combinations of 13 factors. A standard fivefold cross-validation procedure was used to evaluate prediction results.

Results

For LPI change prediction using support vector machine, wall thickness was the optimal single-factor predictor with area under curve (AUC) 0.883 and the AUC of optimal combinational-factor predictor achieved 0.963. For CTI change prediction using discriminant analysis, minimum cap thickness was the optimal single-factor predictor with AUC 0.818 while optimal combinational-factor predictor achieved an AUC 0.836. Using random forest for predicting MPVI change, minimum cap thickness was the optimal single-factor predictor with AUC 0.785 and the AUC of optimal combinational-factor predictor achieved 0.847.

Conclusion

This feasibility study demonstrated that machine learning methods could be used to accurately predict plaque vulnerability change based on morphological and biomechanical factors from multi-modality image-based FSI models. Large-scale studies are needed to verify our findings.

A prediction tool for plaque progression based on patient-specific multi-physical modeling

Atherosclerotic plaque rupture is responsible for a majority of acute vascular syndromes and this study aims to develop a prediction tool for plaque progression and rupture. Based on the follow-up coronary intravascular ultrasound imaging data, we performed patient-specific multi-physical modeling study on four patients to obtain the evolutional processes of the microenvironment during plaque progression. Four main pathophysiological processes, i.e., lipid deposition, inflammatory response, migration and proliferation of smooth muscle cells (SMCs), and neovascularization were coupled based on the interactions demonstrated by experimental and clinical observations. A scoring table integrating the dynamic microenvironmental indicators with the classical risk index was proposed to differentiate their progression to stable and unstable plaques. The heterogeneity of plaque microenvironment for each patient was demonstrated by the growth curves of the main microenvironmental factors. The possible plaque developments were predicted by incorporating the systematic index with microenvironmental indicators. Five microenvironmental factors (LDL, ox-LDL, MCP-1, SMC, and foam cell) showed significant differences between stable and unstable group (p < 0.01). The inflammatory microenvironments (monocyte and macrophage) had negative correlations with the necrotic core (NC) expansion in the stable group, while very strong positive correlations in unstable group. The inflammatory microenvironment is strongly correlated to the NC expansion in unstable plaques, suggesting that the inflammatory factors may play an important role in the formation of a vulnerable plaque. This prediction tool will improve our understanding of the mechanism of plaque progression and provide a new strategy for early detection and prediction of high-risk plaques.

Besides the traditional systematic factors, the influences of the local microenvironmental factors on atherosclerotic plaque progression have been demonstrated. Mathematical and computational modeling is an important tool to investigate the complex interplay between plaque progression and the microenvironment, and provides a potential way toward the prediction of plaque vulnerability according to the comprehensive evaluation of both morphological and/or biochemical factors in tissue level with microenvironmental factors in cellular level. We performed patient-specific multi-physical modeling study on four patients to obtain the evolutional processes of the microenvironment during plaque progression and predicted the possible plaque developments. A scoring table integrating the dynamic microenvironmental indicators with the classical risk index was proposed to differentiate their progression to stable and unstable plaques. Based on patient-specific imaging data, the mathematical model will provide a novel method to predict the changes of plaque microenvironment and improve ability to access the personal therapeutic strategy for atherosclerotic plaque.

Comparisons of simulation results between passive and active fluid structure interaction models for left ventricle in hypertrophic obstructive cardiomyopathy

BACKGROUND

Patient-specific active fluid-structure interactions (FSI) model is a useful approach to non-invasively investigate the hemodynamics in the heart. However, it takes a lot of effort to obtain the proper external force boundary conditions for active models, which heavily restrained the time-sensitive clinical applications of active computational models.

METHODS

The simulation results of 12 passive FSI models based on 6 patients' pre-operative and post-operative CT images were compared with corresponding active models to investigate the differences in hemodynamics and cardiac mechanics between these models.

RESULTS

In comparing the passive and active models, it was found that there was no significant difference in pressure difference and shear stress on mitral valve leaflet (MVL) at the pre-SAM time point, but a significant difference was found in wall stress on the inner boundary of left ventricle (endocardium). It was also found that pressure difference on the coapted MVL and the shear stress on MVL were significantly decreased after successful surgery in both active and passive models.

CONCLUSION

Our results suggested that the passive models may provide good approximated hemodynamic results at 5% RR interval, which is crucial for analyzing the initiation of systolic anterior motion (SAM). Comparing to active models, the passive models decrease the complexity of the modeling construction and the difficulty of convergence significantly. These findings suggest that, with proper boundary conditions and sufficient clinical data, the passive computational model may be a good substitution model for the active model to perform hemodynamic analysis of the initiation of SAM.

Using optical coherence tomography and intravascular ultrasound imaging to quantify coronary plaque cap thickness and vulnerability: a pilot study

Background

Detecting coronary vulnerable plaques in vivo and assessing their vulnerability have been great challenges for clinicians and the research community. Intravascular ultrasound (IVUS) is commonly used in clinical practice for diagnosis and treatment decisions. However, due to IVUS limited resolution (about 150–200 µm), it is not sufficient to detect vulnerable plaques with a threshold cap thickness of 65 µm. Optical Coherence Tomography (OCT) has a resolution of 15–20 µm and can measure fibrous cap thickness more accurately. The aim of this study was to use OCT as the benchmark to obtain patient-specific coronary plaque cap thickness and evaluate the differences between OCT and IVUS fibrous cap quantifications. A cap index with integer values 0–4 was also introduced as a quantitative measure of plaque vulnerability to study plaque vulnerability.

Methods

Data from 10 patients (mean age: 70.4; m: 6; f: 4) with coronary heart disease who underwent IVUS, OCT, and angiography were collected at Cardiovascular Research Foundation (CRF) using approved protocol with informed consent obtained. 348 slices with lipid core and fibrous caps were selected for study. Convolutional Neural Network (CNN)-based and expert-based data segmentation were performed using established methods previously published. Cap thickness data were extracted to quantify differences between IVUS and OCT measurements.

Results

For the 348 slices analyzed, the mean value difference between OCT and IVUS cap thickness measurements was 1.83% (p = 0.031). However, mean value of point-to-point differences was 35.76%. Comparing minimum cap thickness for each plaque, the mean value of the 20 plaque IVUS-OCT differences was 44.46%, ranging from 2.36% to 91.15%. For cap index values assigned to the 348 slices, the disagreement between OCT and IVUS assignments was 25%. However, for the OCT cap index = 2 and 3 groups, the disagreement rates were 91% and 80%, respectively. Furthermore, the observation of cap index changes from baseline to follow-up indicated that IVUS results differed from OCT by 80%.

Conclusions

These preliminary results demonstrated that there were significant differences between IVUS and OCT plaque cap thickness measurements. Large-scale patient studies are needed to confirm our findings.

Identification and application of the Pigm-1 gene in rice disease resistance breeding

Rice blast, caused by Magnaporthe oryzae, is one of the most destructive diseases of rice worldwide. The identification and utilization of resistance genes are crucial and significant for breeding resistant rice cultivars. We identified a resistance gene from Shuangkang77009, which is highly resistant to the rice blast isolate Guy11 using map-based cloning. We performed bulked segregant analysis combined with specific length amplified fragment sequencing. We also performed association analysis, candidate gene prediction and cDNA sequencing to identify the candidate gene. The resistance gene is located on chromosome 6, and we ultimately mapped the resistance locus to a 92-kb region. The resistance gene in Shuangkang77009 was allelic to PigmR, hereafter referred to as Pigm-1. The Pigm-1 protein had one amino acid change: serine (Ser) residue 860 was replaced by tyrosine (Tyr) in Pigm-1 compared with the previously identified Pigm protein, which significantly changed the structure of the Pigm-1 protein based on 3-D structure simulation. In addition, using the developed molecular marker linked to the Pigm-1 gene and molecular marker-assisted selection technology, we introduced the Pigm-1 gene into Minghui86, a widely used and excellent restorer. We generated 11 stable homozygous rice lines with desirable agronomic traits and strong resistance to rice blast. In conclusion, Pigm-1, a natural allelic variant of PigmR, was responsible for blast resistance in Shuangkang77009 rice. The molecular marker-assisted breeding strategy for Pigm-1 was highly efficient.

IDENTIFICATION OF A NOVEL MUTATION IN THE MMAA GENE IN A CHINESE BOY WITH ISOLATED METHYLMALONIC ACIDEMIA

Background

Isolated methylmalonic acidemia refers to a group of inborn errors of metabolism characterized by elevated methylmalonic acid concentrations in the blood and urine. It occurs in approximately one to three out of every 100 thousand Chinese newborns. Mutations in the MMAA gene cause isolated methylmalonic acidemia.

Case presentation

A 13-month-old boy was diagnosed with isolated methylmalonic acidemia. We identified two mutations in the MMAA gene in this case: c.491G>A and c.650T>A. The c.491G>A is a novel mutation in the MMAA gene. The boy is a heterozygous carrier of both mutations. The boy was treated with intravenous sodium benzoate and fluids. His sensorium gradually improved and he recovered from the acute illness. Other family members are heterozygous carriers of either mutations but with no symptoms.

Conclusions

We identified a novel c.491G>A mutation in the MMAA gene. Heterozygous carriers of both c.491G>A and c.650T>A mutations are associated with isolated methylmalonic acidemia.