Induced atrial fibrillation during defibrillation test on implantation of subcutaneous implantable cardioverter defibrillator

The subcutaneous implantable cardioverter defibrillator(S-ICD)has become an alternative to the transvenous ICD in indicated patients.However,inappropriate shock or failed ventricular tachycardia/fibrillation conversion is the most alarming complication of S-ICD.Therefore,defibrillation test(DFT)is recommended for the S-ICD implantation.

Effects of subcutaneous implant of peripheral nerve allograft on the regeneration of defected sciatic nerve

BAEKGROUND： Some experimental studies demonstrate that subcutaneous implant of allograft can significantly decrease lymphocyte infiltration and reduce immunological reaction. However, compared with autologous nerve grafting, what is the effect of nerve regeneration after repair？OB]EETIVE： To observe the local nervous status of the detected part of sciatic nerve repaired through subcutaneously implanting peripheral nerve allograft, and compare the effect with fresh autologous nerve grafting.DESTGN ： Contrast observation.SETTING ： Departments of Orthopaedics of Zhengzhou Fifth People＇s Hospital and First Hospital Affiliated to Chongqing Medical University.MATEREALS ： Totally 30 healthy adult Wistar male rats, with body mass of （200±20）g, were enrolled. Optical microscope （Olympus biological microscope BHS, Japan）, Electron microscope （H-600, Japan）,CM-2000 biomedical image analysis system （CM-2000,Beihang） and myoelectricity scanner （KEYPOINT, Denmark） were used in this experiment.METHODS ： This experiment was carried out in the Orthopaedic Laboratory of Chongqing Medical University between October 2000 and April 2002. ① Six rats were chosen as the donors for allogenic nerve grafting, and 15 mm sciatic nerve segment was chosen as graft. The other rats were randomly divided into two groups： allogenic nerve grafting group and autologous nerve grafting group, with 12 rats in each group. In the allogenic nerve grafting group, a skin incision was made on the posterior side of right thigh, and subcutaneous blunt dissection was performed prorsally a little, then allograft was implanted. Two weeks later, sciatic nerve was exposed at the posterior side of left thigh and cut respectively at 5 mm and another 10 mm away from pelvis. The donor nerve （with connective tissue veil） implanted subcutaneously on the right thigh was taken out. Sectioned connective tissue at the proximal end was trimmed and that at the distal end as done but reserved 10 mm in length, and inosculated antegradely at the nerve defect on the left side with 11/0 nylon line. Twelve rats in autologous nerve grafting group underwent a 10 mm sciatic nerve defect inci- sion on the right thigh and implant of fresh sciatic nerve from left thigh. The incision on the left thigh was repaired in situ. ②2,4,8 and 14 weeks after grafting, the nerve specimen of anastomosis segment was observed under optical microscope. Fourteen weeks after grafting, the ultrathin section of distal sciatic nerve was observed under transmission electron microscope. The number and size of regenerated axons at the cross section of anastomosis of proximal and distal sciatic nerve were analyzed with biomedical image analysis system. Neuroelectrophysiological change of in vivo sciatic nerve was detected with myoelectricity scanner.③ t test was used in the comparison of difference of measurement data.MAZN OUTCOME MEASURES ： ① Observation of anastomosis part of sciatic nerve under optical and electron microscopes in the two groups. ② Comparison of motor nerve conduction velocity, latent period and action potential peak as well as the number and size of cross-section of anastomosis part of proximal and distal sciatic nerve between two groups.RESULTS： ①Observation under optical microscope：Two weeks after grafting, neve axon of repaired region broke and medullary sheath denatured in the allogenic nerve grafting group and autologous nerve grafting group. At the same time, vascular engorgement and a little lymphocytes infiltration were found in the autologous nerve grafting group, but those were found worsened in the allogenic nerve grafting group. Four weeks after grafting, the intensity of the inflammatory reaction was similar between two groups, some collagen fibers at the proximal end proliferated; 8 weeks after grafting, the inflammatory reaction ended basically and the collagen fibers proliferated obviously in the two groups. ② Observation under electron microscope： Fourteen weeks after grafting, the structure of epineurium was in integrity and there were no obvious differences in perineurium and endonurium between two groups. A large number of myelinated nerve fibers and a few unmyelinated nerve fibers regenerated. The structure of myelin sheath was in integrity. ③The number and size of regenerated axons of anastomosis of proximal and distal sciatic nerve had no significant difference 14 weeks after grafting [（575.500±7.495） vs（585.700±11.172） axons/visual field ; （389.300±49.073） vs （407.600±0.283） axons/visual field;（6 423.830±119.911 ） vs （6 695.36± 84.287） μm^2/visual field = （ 5 980.110±74.572） vs（5 980.110±74.572） μm^2/visual field] （P 〉 0.05）. ④ Neuroelectrophysiological examination showed that there were no significant differences in motor nerve evoked potential latent pedod[（1.420±0.346）vs （1.237±0.250） ms] , motor nerve conduction velocity [（ 12.120±0.906 ） vs（13.020±0.599） m/s]and latent period of sciatic nerve [（0.500±0.380）vs （1.250±1.067） mV] of rats between two groups （P 〉 0.05）.CONCLUSTON： Although subcutaneous implant of peripheral nerve allograft has some inflammatory reactions, no obvious rejection is found. Repair results of two groups show that subcutaneous implant of allograft can promote nerve regeneration, which is similar to autologous nerve grafting.

Implantation of an S-ICD in a Patient with a DDD Pacemaker and Congenitally Corrected Transposition of the Great Arteries

Subcutaneous implantable cardioverter-defi brillator(S-ICD)therapy has become a viable alternative to conventional transvenous ICD implantation.Patients with congenitally corrected transposition of the great arteries(ccTGA)have a high risk of sudden cardiac death due to malignant arrhythmia.The interaction between the S-ICD system and the transvenous pacemaker system is not fully understood.We report a case of S-ICD implantation in a patient with ccTGA and a DDD pacemaker.The patient was a 30-year-old man with a previously placed pacemaker with diagnoses of congenital heart disease,ccTGA(SLL),left atrioventricular valve insuffi ciency,and third-degree atrioventricular block.He presented with an out-of-hospital cardiac arrest,and an S-ICD was implanted to prevent sudden cardiac death.Defi brillation checks were performed successfully.We tested the compatibility of the DDD pacemaker with the S-ICD and found that there was no interference between them.In conclusion,an S-ICD system is a reasonable and safe option in patients with ccTGA.

Microencapsulated tumor assay:Evaluation of the nude mouse model of pancreatic cancer

AIM: To establish a more stable and accurate nude mouse model of pancreatic cancer using cancer cell microencapsulation. METHODS: The assay is based on microencapsulation technology, wherein human tumor cells are encapsulated in small microcapsules (approximately 420 μm in diameter) constructed of semipermeable membranes. We implemented two kinds of subcutaneous implantation models in nude mice using the injection of single tumor cells and encapsulated pancreatic tumor cells. The size of subcutaneously implanted tumors was observed ona weekly basis using two methods, and growth curves were generated from these data. The growth and metastasis of orthotopically injected single tumor cells and encapsulated pancreatic tumor cells were evaluated at four and eight weeks postimplantation by positron emission tomography-computed tomography scan and necropsy. The pancreatic tumor samples obtained from each method were then sent for pathological examination. We evaluated differences in the rates of tumor incidence and the presence of metastasis and variations in tumor volume and tumor weight in the cancer microcapsules vs single-cell suspensions. RESULTS: Sequential in vitro observations of the microcapsules showed that the cancer cells in microcapsules proliferated well and formed spheroids at days 4 to 6. Further in vitro culture resulted in bursting of the membrane of the microcapsules and cells deviated outward and continued to grow in flasks. The optimum injection time was found to be 5 d after tumor encapsulation. In the subcutaneous implantation model, there were no significant differences in terms of tumor volume between the encapsulated pancreatic tumor cells and cells alone and rate of tumor incidence. There was a significant difference in the rate of successful im- plantation between the cancer cell microencapsulation group and the single tumor-cell suspension group (100% vs 71.43%, respectively, P = 0.0489) in the orthotropic implantation model. The former method displayed an obvious advantage in tumor mass (4th wk: 0.0461 ± 0.0399 vs 0.0313 ± 0.021, t = -0.81, P = 0.4379; 8th wk: 0.1284 ± 0.0284 vs 0.0943 ± 0.0571, t = -2.28, respectively, P = 0.0457) compared with the latter in the orthotopic implantation model. CONCLUSION: Encapsulation of pancreatic tumor cells is a reliable method for establishing a pancreatic tumor animal model.

Review of minimally invasive continuous glucose monitoring technology & instruments

Continuous blood glucose monitoring is important for the diagnosis,treatment,and study of diabetes. many organizations have been working on this subject in recent two decades. Glucose concentration in interstitial fluid is closely related to the blood glucose levels. Minimally invasive continuous blood glucose monitoring technology based on the glucose detection in interstitial fluid develops rapidly and gets more and more attentions from the patients and the doctors,due to its instantaneous real-time display of glucose level,"24/7"coverage,and the ability to characterize glycemic variability. According to the different detection methods,most of the continuous glucose monitoring technology could be divided into two kinds: subcutaneous implantation method and transdermal extraction method. This paper review s the recent development of minimally invasive blood glucose monitoring technology and instruments. The mainly remained challenges and related research directions are presented as well.

Hydrogels of Chemically Cross-linked and Organ-metallic Complexed Interpenetrating PEG Networks

The aim of the present work was to prepare a well-defined hydrogel of chemically cross-linked and organ-metallic complexed interpenetrating PEG networks. The hydrogel was synthesized via the reaction of copper（I）- catalyzed 1,3-dipolar azide-alkyne cycloaddition（CuA AC） with poly（ethylene glycol）-dopamine（PEG-DA）（“Click Chemistry”） followed by complexation with Fe-（3＋） ions to crosslink the polymeric network. The chemical composition and morphology of the resulting hydrogels were characterized by Fourier transform infrared spectroscopy（FTIR）, -1H-NMR and scanning electron microscopy（SEM）. Swelling ratio, mechanical strength, conductivity, and degradation behaviors of the hydrogels were also studied. The effect of the polymer chain length on properties of hydrogels was explored. The compressive strength of hydrogels could reach as high as 13.1 MPa with a conductivity of 2.2 × 10^-5 S·cm^-1. The hydrogels also exhibited excellent thermal stability even at a temperature of 300 °C, whereas degradation of the hydrogel after 7 weeks was observed under a physiological condition. In addition, the hydrogel exhibited a good biocompatibility based on its in vivo performance through an in vivo subcutaneous implantation model. No inflammation and no obvious abnormality of the surrounding tissue were observed when the hydrogel was subcutaneously implanted for 2 weeks. This work is a step towards creating a new pathway to synthesize hydrogels of interpenetrating networks which could be of important applications in the future research.