The objective of the study is to analyze the biological characteristics and stability of the linear derivative Bac2a from bactenecin, compared with the control peptide melittin. The secondary structure, antibacterial activity, hemolytic activity, cell toxicity and stability of the Bac2a were determined by circular dichroism spectroscopy, broth micro-dilution method and MTT assay. The results showed that Bac2a was a nonregular curl in aqueous solution, however, it was an α-helix structure in the hydrophobic environment. The minimal inhibitory concentration (MIC) of Bac2a ranged from 2 to 32 μmol/L, so the bacteriostatic activity of Bac2a was strong. The hemolytic rate was only 14.81% when the concentration of Bac2a was 64 μmol/L, which showed that the hemolytic rate of Bac2a was low. The therapy index of Bac2a was 3.26, and the cytotoxicity was relatively low, thus the cell selectivity was relatively high. In addition, with the heating treatment of 100℃ for 1 h, Bac2a still possessed rather a high antibacterial activity and showed a good heating stability. In a word, Bac2a has good application prospects in food, medicine and other fields, and is expected as a substitute for traditional antibiotics.
目的:研究O型RhD阳性孕妇(其丈夫为非O型)血清IgG抗-A(抗-B)抗体效价与新生儿溶血病(HDN)的关系。方法:应用微柱凝胶技术对382例O型RhD阳性孕妇进行了免疫性IgG抗A(B)抗体效价检测及对其新生儿进行HDN(①新生儿ABO、Rh系统定型;②新生儿直抗实验;③游离IgG测定;④放散实验)的检测。结果:382例O型RhD阳性孕妇中IgG抗-A(B)效价lt;64者330例(占总数86.39%),抗体效价≥64者13.61%。其中发生HDN 5例,抗-A 3例,抗-B12例,总发生率1.31%.结论:夫妇血型不合应及时检测孕妇IgG抗体,随着孕妇体内IgG抗体效价的增高,新生儿ABO溶血病的发病率也随之升高。孕妇产前应定时进行IgG抗体检测,了解效价与新生儿溶血病发病率之问的关系,对于预防新生儿溶血病极为有效。
An implantable axial blood pump was designed according to the circulation assist requirement of severe heart failure patients of China. The design point was chosen at 3 L/min flow rate with 100 mm Hg pressure rise when the blood pump can provide flow rates of 2-7 L/min. The blood pump with good hemolytic and anti-thrombogenic property at widely operating range was designed by developing a structure that including the spindly rotor impeller structure and the diffuser with splitter blades and cantilevered main blades. Numerical simulation and particle image velocimetry (PIV) experiment were conducted to analyze the hydraulic, flow fields and hemolytic performance of the blood pump. The results showed that the blood pump could provide flow rates of 2-7 L/min with pressure rise of 60.0-151.3 mm Hg when the blood pump rotating from 7 000 to 11 000 r/min. After adding the splitter blades, the separation flow at the suction surface of the diffuser has been reduced efficiently. The cantilever structure changed the blade gap from shroud to hub that reduced the tangential velocity from 6.2 m/s to 4.3-1.1 m/s in blade gap. Moreover, the maximum scalar shear stress of the blood pump was 897.3 Pa, and the averaged scalar shear stress was 37.7 Pa. The hemolysis index of the blood pump was 0.168% calculated with Heuser’s hemolysis model. The PIV and simulated results showed the overall agreement of flow field distribution in diffuser region. The blood damage caused by higher shear stress would be reduced by adopting the spindle rotor impeller and diffuser with splitter blades and cantilevered main blades. The blood could flow smoothly through the axial blood pump with satisfactory hydraulics performance and without separation flow.
Abstract: Objective To summarize the clinical experience of plasma exchange （PE） during recardiopulmonary bypass (CPB) of patients with severe haemolysis in cardiac surgery. Methods Between January 2001 and December 2005, five patients required PE for severe haemolysis after cardiac surgery. There were periprosthetic leakage and infective endocarditis in 3 patients, congenital heart disease of pulmonary artery stenosis with unsatisfied right ventricular outflow tract patching in 1 patient and thrombosis during extracorporeal membrane oxygenation (ECMO) in 1 patient. They all need blood purification to avoid acute renal failure. Results Five patients were successfully treated with PE during CPB without major complications. The amount of plasma and blood transfused in the 5 patients were 2.2±0.8L and 0.6±0.3L respectively. The volume of plasma exchange and ultrafiltrate were 3.9±1.8L and 2.4±1.3L respectively.The electrolytes and bloodgas analysis in all patients were maintained at the normal levels. The hemodynamics was stable. After heart resuscitation CPB stopped smoothly. Disappearance of periprosthetic leakage and satisfaction of right ventricular outflow tract patching were observed by echocardiograms after peration.Extubation was performed 24h after the operation in 5 patients, and they were discharged 12 to 53 d after the operation with fully recovery. The urine was clear and the body temperature was normal. Before they left thehospital, the concentration of free hemoglobin was tested in 3 patients. The concentration of free hemoglobin was slightly higher in 1 patient (68mg/L), and normal in 2 patients (lt;40mg/L). Conclusion PE during CPB in severe haemolysis is a safe technique which can effectively prevent acute renal failure caused by severe mechanical haemolysis after cardiac surgery.
Red blood cells are destroyed when the shear stress in the blood pump exceeds a threshold, which in turn triggers hemolysis in the patient. The impeller design of centrifugal blood pumps significantly influences the hydraulic characteristics and hemolytic properties of these devices. Based on this premise, the present study employs a multiphase flow approach to numerically simulate centrifugal blood pumps, investigating the performance of pumps with varying numbers of blades and blade deflection angles. This analysis encompassed the examination of flow field characteristics, hydraulic performance, and hemolytic potential. Numerical results indicated that the concentration of red blood cells and elevated shear stresses primarily occurred at the impeller and volute tongue, which drastically increased the risk of hemolysis in these areas. It was found that increasing the number of blades within a certain range enhanced the hydraulic performance of the pump but also raised the potential for hemolysis. Moreover, augmenting the blade deflection angle could improve the hemolytic performance, particularly in pumps with a higher number of blades. The findings from this study can provide valuable insights for the structural improvement and performance enhancement of centrifugal blood pumps.
The evaluation of blood compatibility of biomaterials is crucial for ensuring the clinical safety of implantable medical devices. To address the limitations of traditional testing methods in real-time monitoring and electrical property analysis, this study developed a portable electrical impedance tomography (EIT) system. The system uses a 16-electrode design, operates within a frequency range of 1 to 500 kHz, achieves a signal to noise ratio (SNR) of 69.54 dB at 50 kHz, and has a data collection speed of 20 frames per second. Experimental results show that the EIT system developed in this study is highly consistent with a microplate reader (R2=0.97) in detecting the hemolytic behavior of industrial-grade titanium (TA3) and titanium alloy—titanium 6 aluminum 4 vanadium (TC4) in anticoagulated bovine blood. Additionally, with the support of a multimodal image fusion Gauss-Newton one-step iterative algorithm, the system can accurately locate and monitor in real-time the dynamic changes in blood permeation and coagulation caused by TC4 in vivo. In conclusion, the EIT system developed in this study provides a new and effective method for evaluating the blood compatibility of biomaterials.
Hemolysis is one of the main complications associated with the use of ventricular assist devices. The primary factors influencing hemolysis include the shear stress and exposure time experienced by red blood cells. In addition, factors such as local negative pressure and temperature may also impact hemolysis. The different combinations of hemolysis prediction models and their empirical constants lead to significant variations in prediction results; compared to the power-law model, the OPO model better accounts for the complexity of turbulence. In terms of improving hemolytic performance, research has primarily focused on optimizing blood pump structures, such as adjustments to pump gaps, impellers, and guide vanes. A small number of scholars have studied hemolytic performance through control modes of blood pump speed and the selection of blood-compatible materials. This paper reviews the main factors influencing hemolysis, prediction methods, and improvement strategies for rotary blood pumps, which are currently the most widely used. It also discusses the limitations in current hemolysis research and provides an outlook on future research directions.
Heart failure is one kind of cardiovascular disease with high risk and high incidence. As an effective treatment of heart failure, artificial heart is gradually used in clinical treatment. Blood compatibility is an important parameter or index of artificial heart, and how to evaluate it through hemodynamic design and in vitro hemolysis test is a research hotspot in the industry. This paper first reviews the research progress in hemodynamic optimization and in vitro hemolysis evaluation of artificial heart, and then introduces the research achievements and progress of the team in related fields. The hemodynamic performance of the blood pump optimized in this paper can meet the needs of use. The normalized index of hemolysis obtained by in standard vitro hemolysis test is less than 0.1 g/100 L, which has good hemolysis performance in vitro. The optimization method described in this paper is suitable for most of the development of blood pump and can provide reference for related research work.