Influence of different preoperative corneal curvature on the size of optical deformation area after femtosecond laser small incision lenticule extraction / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the effect of different preoperative corneal curvature on the size of optical deformation area after femtosecond laser small incision lens extraction(SMILE).METHODS:A prospective study was conducted on 108 consecutive patients who underwent SMILE surgery in our hospital from February 2021 to January 2022. Considering the association between both eyes, only the left eye of each patient was studied. According to the average anterior corneal surface curvature in preoperative, the patients were divided into three groups: Km<42.0D group(n=30), Km>47.0D group(n=26)and conventional corneal curvature group(n=52)with 42.0D≤Km≤47.0D. All patients underwent standardized SMILE surgery, and the laser ablation diameter was 6.5mm. The diameters of optical deformation areas in the three groups were compared at 6mo after operation.RESULTS:There was no significant difference in preoperative data among the three groups except for the mean curvature of the anterior corneal surface(all P>0.05), and there was no significant difference in uncorrected distance visual acuity(UDVA)and subjective refraction at 6mo after operation(all P>0.05). The diameters of the optical deformation zone in the Km<42.0D group, Km>47.0D group and the conventional corneal curvature group were 6.54±0.14, 6.32±0.13, 6.45±0.15mm respectively(F=19.238, P<0.05). The optical area diameter of the group with flat corneal curvature was larger than that of the group with conventional corneal curvature and the group with steeper corneal curvature(P<0.05). The diameter of optical zone in the conventional curvature group was larger than that in the Km>47.0D group(P<0.05).CONCLUSION: When the preset laser cutting diameter is the same, the steeper the corneal curvature before operation, the smaller the diameter of the optical deformation area after operation.

Analysis on Motion Characteristics of Red Blood Cells in Capillaries / 医用生物力学

Objective To study the motion and deformation of red blood cells ( RBCs) with different mechanical properties in capillaries,and make analysis on the associated hemorheological parameters. Methods The RBC was modeled as a hyper elastic membrane using Skalak model. The fluid was solved using a two-order difference scheme with the membrane mechanics treated by the immersed method. The pathological viscosity ratio λ= 5 was considered. Results The steady deformation of RBCs with different membrane stiffness in the capillary was obtained. With membrane stiffness increasing, the cell transformed from axisymmetric shapes to non-axisymmetric shapes. With capillary number increasing, the deformability of RBCs weakened and the flow resistance increased. Conclusions With stiffening of cell membrane, the non-axisymmetric cell shape appears and the flow resistance increases. Therefore, in diseases involved stiffening RBCs, the stiffened RBCs can cause the blockage of capillaries and hypoxia in surrounding tissues.

Post?Cardiopulmonary Bypass Longitudinal Strain provides Higher Prognostic Ability than Baseline Strain or Change in Strain

Context:Global longitudinal strain (GLS) measured by speckle?tracking echocardiography demonstrates excellent prognostic ability in predicting major adverse cardiac events after cardiac surgery. However, the optimal timing of intraoperative GLS measurement that provides the best prognostic value is unclear. Aim: Our goal was to evaluate whether GLS measured prior to cardiopulmonary bypass (pre?CPB GLS), following CPB (post?CPB GLS), or change in GLS provides the strongest association with postoperative complications. Setting and Design: Post hoc analysis of prospectively collected data from a clinical trial (NCT01187329). 72 patients with aortic stenosis undergoing elective AVR ± coronary artery bypass grafting between January 2011 and August 2013. Material and Methods: Myocardial deformation analysis from standardized transesophageal echocardiographic examinations were performed after anesthetic induction and chest closure. We evaluated the association between pre?CPB GLS, post?CPB GLS, and change in GLS (percent change from pre?CPB baseline) with postoperative atrial fibrillation and hospitalization >7 days. The association of post?CPB GLS with duration of mechanical ventilation, N?terminal pro?BNP (NT?proBNP) and troponin T were also assessed. Statistical Analysis: Multivariable logistic regression. Results: Risk?adjusted odds (OR[97.5%CI] of prolonged hospitalization increased an estimated 27% (1.27[1.01 to 1.59];Padj =0.035) per 1% decrease in absolute post?CPB GLS. Mean[98.3%CI] NT?proBNP increased 98.4[20 to 177]pg/mL; Padj =0.008), per 1% decrease in post?CPB GLS. Pre?CPB GLS or change in GLS were not associated with any outcomes. Conclusions: Post?CPB GLS provides the best prognostic value in predicting postoperative outcomes. Measuring post?CPB GLS may improve risk stratification and assist in future study design and patient outcome research.

Study on the sequence of morphological and angiographic changes due to intraocular pressure elevation in the optic nerve head / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To figure out the sequence of vessel density(VD)changes in the retina and deformation induced by mechanical force in the optic nerve head(ONH)tissue during intraocular pressure(IOP)elevation.<p>METHODS: This prospective study tested 34 eyes from 34 healthy volunteers. Group A had 23 subjects. Their testing protocol included a baseline phase, two elevated IOP phases(15 mmHg and 30 mmHg respectively for 2min), and a recovery phase. Group B had 11 subjects, and their protocol included an IOP elevation of 15 mmHg for 10min. In each phase the deformation in the ONH and macular region were scanned by optical coherence tomography(OCT), and Bruch's membrane opening(BMO)distance, the optic nerve head surface depth(ONHSD), the subfoveal choroidal thickness(SFCT)were measured, the VD was measured by OCTA.<p>RESULTS: After the first IOP elevation in group A, the VD in the ONH decreased(superficial capillary plexuses, from 67.39±7.65% to 43.78±5.89%, <i>P</i><0.05), the BMO distance, the ONHSD, the VD in the macula and the SFCT did not change. After the second IOP elevation, the VD in the ONH and in the macular region both decreased, the BMO distance and ONHSD increased(all <i>P</i><0.05). After the IOP elevation in group B, the VD in the ONH and in the macular region decreased significantly, the BMO distance increased, the SFCT did not change. ONH VD reduction is not associated with BMO distance increment(<i>r</i>=0.050, <i>P</i>>0.05).<p>CONCLUSION:The ONH tissue is more sensitive to hemodynamics than to morphological change. Hemodynamics during IOP elevation differs in the ONH and the macular tissue.

Comprehensive evaluation method of real-time non-reference ultrasound image involving soft tissue deformation / 生物医学工程学杂志

Ultrasound guided percutaneous interventional therapy has been widely used in clinic. Aiming at the problem of soft tissue deformation caused by probe contact force in robot-assisted ultrasound-guided therapy, a real-time non-reference ultrasound image evaluation method considering soft tissue deformation is proposed. On the basis of ultrasound image brightness and sharpness, a multi-dimensional ultrasound image evaluation index was designed, which incorporated the aggregation characteristics of the organization. In order to verify the effectiveness of the proposed method, ultrasound images of four different models were collected for experiments, including prostate phantom, phantom with cyst, pig liver tissue, and pig liver tissue with cyst. In addition, the correlation between subjective and objective evaluations was analyzed based on Spearman's rank correlation coefficient. Experimental results showed that the average evaluation time of a single image was 68.8 milliseconds. The evaluation time could satisfy real-time applications. The proposed method realizes the effective evaluation of real-time ultrasound image quality in robot-assisted therapy, and has good consistency with the evaluation of supervisors.

Deformation Characteristics of Hand Movement During Grasping / 医用生物力学

Objective Based on the multi-camera digital image correlation (DIC) method, the dynamic deformation characteristics of human hand during grasping were studied. Methods A continuous four-camera DIC system was established to measure surface strain of the skin on the back of the hand during grasping process, and then through the connection between skin, joints, bones and muscles, the regular pattern of muscle deformation could be known indirectly. Results Four grasping postures (medium cylinder, lateral pinch, index finger extension, power sphere) were measured. It was found that the increases of strain magnitude were different at different positions on back surface of the hand under different grasping postures, and the maximum principal strains were between 0.1 and 0.3. The movement characteristics for each muscle group of the hand under different grasping postures were obtained through analysis. Conclusions This method has the characteristics of non-contact, full field, intuitive results, which provides a new way for in vivo measurement of dynamic deformation during grasping.

Effects of Different Materials on Thermal Stress Field of Bipolar High-Frequency Electric Knife / 医用生物力学

Objective To analyze the influence of different materials on thermal stress field of the bipolar high-frequency electric knife. Methods The electric-thermal coupling simulation analysis was performed for thermal stress field in working process of the bipolar high-frequency electric knife. The influence patterns for 4 kinds of insulating layer materials 304 stainless steel, 316 stainless steel, 317 stainless steel, Ti6Al4V and 4 kinds of electrode materials polypropylene (PP), polyamide-6 (PA6), polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) on thermal stress field and thermal deformation field of insulating layer, electrode and coating of bipolar high-frequency electric knife and myocardial tissues were studied. Results The thermal deformation of myocardial tissues was much higher than that of the components of high-frequency electric knife in period of 2 s for continuous power. In terms of myocardial tissue protection, 304 stainless steel was the best electrode material for high-frequency electric knife. For choosing PP as the insulating layer material, thermal deformation of myocardial tissues caused by thermal stress was the smallest, which could better maintain the integrity of myocardial tissues. Conclusions The manufacturing materials of high-frequency electric knife have an important influence on thermal stress field in its working process. The regularity analysis results can provide guidance for the development of high-frequency electric knife.

Finite element analysis of the effect of local posterior sclera collagen cross-linking on eyeball shape / 生物医学工程学杂志

China is the country with high incidence of high myopia in the world. High myopia can cause severe vision impairment. So far, there is no effective treatment for high myopia in clinic. Scleral collagen cross-linking surgery has been proven to be effective in preventing animal eye axial elongation

Estudio de la deformación miocárdica longitudinal en pacientes con cardiopatía isquémica / Study of longitudinal myocardial deformation in patients with ischemic cardiopathy

Resumen Introducción: Las enfermedades cardiovasculares constituyen la primera causa de muerte en Cuba y la mayoría de los países desarrollados. La ecocardiografía con speckle tracking bidimensional (ST 2D) es una técnica reciente en la evaluación de la función cardíaca. Objetivos: Determinar la relación entre la deformación miocárdica medida por ST 2D y el estado de la circulación coronaria en pacientes con cardiopatía isquémica, en el CIMEQ, durante un año. Material y método: Se realizó un estudio analítico y transversal con 55 pacientes con indicación de coronariografía sometidos a ecocardiograma bidimensional y estudio de ST 2D con medición de la deformación longitudinal (DLG). Se crearon dos grupos: enfermedad coronaria significativa (ECS = 32) y no significativa (ECNS = 23). Se utilizó SSPS para análisis de los resultados. Resultados: La edad promedio fue mayor en la ECS (55.6 ± 9.3 vs. 61.8 ± 8.8; p = 0.014). Predominaron los hombres con ECS (47.3%), los hipertensos (ECS = 90.6% y ENCS = 65.2%; p = 0.02) y los fumadores (ECS = 59.4% y ENCS = 17.4%; p = 0.002). El diagnóstico más frecuente fue la angina crónica estable (87%). En la ECS predominó la enfermedad de tres vasos (75%). La DLG fue menor en la ECS [(-20.0 ± 3.2 vs. -22.1 ± 3.6; p = 0.035); AUC = 0.458]. No hubo diferencias en la DLG según el número de vasos significativamente afectados. Conclusiones: Los resultados encontrados no justifican el empleo del ST 2D para diferenciar la ECS.

Abstract Introduction: Cardiovascular diseases are the leading cause of death in Cuba and most of the developed countries. Two-dimensional speckle tracking echocardiography (2D ST) is a recent technique in the evaluation of cardiac function. Objectives: To determine the relationship between myocardial deformation measured by 2D ST and coronary circulation in patients with ischemic heart disease, in the CIMEQ, for 1 year. Material and method: An analytical, cross-sectional study was carried out with 55 patients with an indication for coronary angiography who underwent 2D echocardiography and 2D ST study with longitudinal strain measurement (LSM). Two groups significant coronary disease (SCD = 32) and not significant (NSCD = 23) were created. SSPS was used to analyze the results. Results: The average age was higher in SCD (55.6 ± 9.3 vs. 61.8 ± 8.8, p = 0.014). Men with SCD (47.3%), hypertensive (SCD = 90.6% and NSCD = 65.2%, p = 0.02) and smokers (SCD = 59.4% and NSCD = 17.4%, p = 0.002) predominated. The most frequent diagnosis was chronic stable angina (87%). Three-vessel disease (75%) prevailed in SCD. The LMS was lower in SCD ([−20.0 ± 3.2 vs. −22.1 ± 3.6, p = 0.035]; AUC = 0.458). There were no differences in LSM according to the number of significantly diseased vessels. Conclusions: The results found do not justify the use of 2D ST to discriminate SCD.

Discondrosteosis de Léri-Weill. Presentación de una familia afectada / Léri-Weill dyschondrosteosis. Presentation of an affected family

RESUMEN Fundamentación: La discondrosteosis de Léri-Weill, displasia ósea de origen genético que afecta la región mesomélica con acortamiento de las extremidades, provoca talla baja con extremidades cortas con deformidad de Madelung; esta enfermedad muestra un patrón de herencia autosómico dominante con alta penetrancia. Objetivo: Describir las deformidades de esta discondrosteosis de baja frecuencia con expresividad variable, que se presentó de la misma forma en todos los afectados de esta familia. Presentación de caso: Se reportó una familia con enfermos en tres generaciones con deformidad de Madelung de ambas muñecas y baja estatura de origen mesomélico, que se mantiene seguimiento en consultas de Genética Clínica y Ortopedia. Conclusiones: El examen físico y radiológico imprescindibles para llegar al diagnóstico clínico. El método clínico y la valoración multidisciplinaria resultaron de gran valor para definir esta enfermedad y poder brindar un adecuado asesoramiento genético a esta familia.

ABSTRACT Background: Léri-Weill dyschondrosteosis, bone dysplasia of genetic origin that affects the mesomelic region with shortening of the extremities, causes short stature with short extremities with Madelung deformity.This disease shows an autosomal dominant inheritance pattern with high penetrance. Objective: To describe the deformities of this low frequency dyschondrosteosis with variable expressivity which was presented in the same way in all those affected in this family. Case presentation: A family with sick members was reported in three generations with Madelung deformity of both wrists and short stature of mesomelic origin which is followed up in consultations of Clinical Genetics and Orthopedics. Conclusion: The essential physical and radiological examination to reach the clinical diagnosis. The clinical method and the multidisciplinary assessment were of great value to define this disease and to be able to provide adequate genetic counseling to this family.

A Systematic Characterization of Structural Brain Changes in Schizophrenia / 神经科学通报·英文版

A systematic characterization of the similarities and differences among different methods for detecting structural brain abnormalities in schizophrenia, such as voxel-based morphometry (VBM), tensor-based morphometry (TBM), and projection-based thickness (PBT), is important for understanding the brain pathology in schizophrenia and for developing effective biomarkers for a diagnosis of schizophrenia. However, such studies are still lacking. Here, we performed VBM, TBM, and PBT analyses on T1-weighted brain MR images acquired from 116 patients with schizophrenia and 116 healthy controls. We found that, although all methods detected wide-spread structural changes, different methods captured different information - only 10.35% of the grey matter changes in cortex were detected by all three methods, and VBM only detected 11.36% of the white matter changes detected by TBM. Further, pattern classification between patients and controls revealed that combining different measures improved the classification accuracy (81.9%), indicating that fusion of different structural measures serves as a better neuroimaging marker for the objective diagnosis of schizophrenia.

Effect of different structural parameters of filter rod on mechanical properties of new vena cava filter / 生物医学工程学杂志

The dynamic analysis of the implantation process of a new vena cava filter was carried out by finite element analysis method to reveal the influence of the angle, length, width and thickness of the filter rod on its mechanical properties and the inner wall of the blood vessel. The results showed that the high-stress and high-strain areas of the filter were mainly concentrated in the connection between the filter rod and the filter wire. With the increase of the angle of the filter rod, the maximum equivalent stress and the maximum elastic strain on the filter wall decreased, while the maximum equivalent stress on the vascular wall increased. With the increase of the length of the filter rod, the maximum equivalent stress and strain peak of the filter wall increased, but the maximum equivalent stress of the vessel wall decreased. With the increase of the width and thickness of the filter rod, the maximum equivalent stress of the filter wall, the maximum elastic strain and the maximum equivalent stress of the vessel wall all showed an upward trend. The static safety factor of all filter models was greater than 1, and the structure after implantation was safe and reliable. The results of this study are expected to provide a theoretical basis for the structural optimization and deformation mechanism of the new type vena cava filter.

A Systematic Characterization of Structural Brain Changes in Schizophrenia / 神经科学通报·英文版

A systematic characterization of the similarities and differences among different methods for detecting structural brain abnormalities in schizophrenia, such as voxel-based morphometry (VBM), tensor-based morphometry (TBM), and projection-based thickness (PBT), is important for understanding the brain pathology in schizophrenia and for developing effective biomarkers for a diagnosis of schizophrenia. However, such studies are still lacking. Here, we performed VBM, TBM, and PBT analyses on T1-weighted brain MR images acquired from 116 patients with schizophrenia and 116 healthy controls. We found that, although all methods detected wide-spread structural changes, different methods captured different information - only 10.35% of the grey matter changes in cortex were detected by all three methods, and VBM only detected 11.36% of the white matter changes detected by TBM. Further, pattern classification between patients and controls revealed that combining different measures improved the classification accuracy (81.9%), indicating that fusion of different structural measures serves as a better neuroimaging marker for the objective diagnosis of schizophrenia.

Study on mixing technology of post-crosslinking Daphnes Giraldii Cortex gel plaster based on rheological indexes / 中草药

Objective: To optimize the mixing technology of Daphnes Giraldii Cortex gel plaster (DGCGP) by using rheological parameters elastic modulus (G'), viscous modulus (G″), yield stress (τ0), creep compliance [J(t)] and loss coefficient (tanδ) as evaluation indexes. Methods: Using orthogonal design, L9(34) orthogonal design was used to screen out the best mixing technology of DGCGP and predict the suitable coating conditions by taking the temperature, rotating speed and mixing time of the mixed materials as influencing factors and the rheological parameters of the medicated compound as evaluating indexes. Results: The optimum DGCGP mixing process was as following: 70℃ at 10 r/min for 2 h. Under this condition, the viscoelasticity, temperature and shear resistance, deformation resistance and stability of the mixture were all good. Conclusion: DGCGP prepared by this optimized process had good appearance, soft texture, good adhesion with skin, good viscoelasticity and better quality.

Clinical application and research progress on dose-guided radiotherapy / 中华放射肿瘤学杂志

Dose-guided radiotherapy (DGRT) is a potentially useful adaptive radiotherapy method which dosimetrically compensates for interfractional non-rigid deformation.With the improvement of in-room imaging quality,development of the deformation registration algorithm and innovation of computer science,the wide application of DGRT might be realized.The purpose of this article is to briefly summarize the work flow,clinical application and prospect of DGRT.

Clinical application and research progress on dose-guided radiotherapy / 中华放射肿瘤学杂志

Dose-guided radiotherapy (DGRT) is a potentially useful adaptive radiotherapy method which dosimetrically compensates for interfractional non-rigid deformation. With the improvement of in-room imaging quality, development of the deformation registration algorithm and innovation of computer science, the wide application of DGRT might be realized. The purpose of this article is to briefly summarize the work flow, clinical application and prospect of DGRT.

Comparison of finite element models of osteonecrosis of the femoral head based on CT gray-assigned method / 中国组织工程研究

BACKGROUND: Previous studies have reported that femoral head finite element models are mostly modeled with single or few samples for specific biomechanical research, but there is little research on model stability. OBJECTIVE: To compare the models of normal femoral head and osteonecrosis of the femoral head with multiple samples, and to analyze the accuracy and stability of the models through the comparison of stress distribution and mechanical parameters, so as to provide mechanical basis for prevention and treatment of collapse of osteonecrosis of the femoral head. METHODS: Totally 20 sides uncollapsed of osteonecrosis of the femoral head one year of non-surgical treatment were selected as the experimental group, and the healthy side of 20 patients with unilateral osteonecrosis of the femoral head were set as the normal group. The CT data of the femoral head were collected to establish the finite element model. The stress distribution of normal femoral head and osteonecrosis of the femoral head, the maximum equivalent stress and the maximum total deformation at the weight-bearing area of the femoral head were observed and compared. This study was approved by the Medical Ethics Committee of Wangjing Hospital of China Academy of Chinese Medical Sciences. Patients signed the informed consent. RESULTS AND CONCLUSION: (1) The finite element models of normal proximal femur, non-necrotic proximal femur and necrotic bone were established. The number of elements and nodes were 502 568±114 196, 692 608±154 678; 449 954±125 824, 623 311±171 401; 19 133±13 167, 27 577±19 131, respectively. (2) When the load was set by simulating one-foot standing position, the cloud image showed that when 2.5 times body weight applied to the weight-bearing area of the femoral head; the surface stress of the weight-bearing area of the normal femoral head was uniform. The stress was uniformly distributed in the femoral head along the stress trabeculae, and the calcar femorale bears the most. The stress concentration area appeared on the surface of the weight-bearing area and the necrotic area of osteonecrosis of the femoral head. The stress was scattered and distributed on the inner and outer sides of the femoral neck and the femoral head of osteonecrosis of the femoral head produced more deformation than the normal femoral head. (3) The maximum total deformation of the weight-bearing area of the osteonecrosis of the femoral head and the normal femoral head was (4.14±1.31) mm and (1.36±0.22) mm and the maximum equivalent stress was (1.94±0.77) MPa and (0.75±0.19) MPa, respectively, and with statistically significance (P < 0.05). Moreover, two groups of data tend to be concentrated and the models are stable. Through the comparison of multi-sample normal femoral head and osteonecrosis of the femoral head, the CT gray-assigned method reflects the actual mechanical properties of osteonecrosis of the femoral head, and has good accuracy and stability.