Mechanism studies for relativistic attosecond electron bunches from laser-illuminated nanotargets

To find a way to control the electron-bunching process and the bunch-emitting directions when an ultraintense, linearly polarized laser pulse interacts with a nanoscale target, we explored the mechanisms for the periodical generation of relativistic attosecond electron bunches. By comparing the simulation results of three different target geometries, the results show that for nanofoil target, limiting the transverse target size to a small value and increasing the longitudinal size to a certain extent is an effective way to improve the total electron quantity in a single bunch. Then the subfemtosecond electronic dynamics when an ultrashort ultraintense laser grazing propagates along a nanofoil target was analyzed through particle-in-cell simulations and semiclassical analyses, which shows the detailed dynamics of the electron acceleration, radiation, and bunching process in the laser field. The analyses also show that the charge separation field produced by the ions plays a key role in the generation of electron bunches, which can be used to control the quantity of the corresponding attosecond radiation bunches by adjusting the length of the nanofoil target.

[Serum immunoglobulin concentration and the risk of type 2 diabetes mellitus in adults in Tianjin City: a prospective cohort study]

Objective: To evaluate the association between immunoglobulin concentration and the risk of type 2 diabetes mellitus (T2DM) in adults in Tianjin City. Methods: Based on the Tianjin Chronic Low-grade Systemic Inflammation and Health (TCLSIHealth) cohort from January 2010 to December 2018, subjects who had completed the measurement of baseline immunoglobulin concentration and blood glucose concentration and not been diagnosed with any type of diabetes at baseline were selected in this study. The collected data included the concentration of serum immunoglobulin (IgG, IgM, IgA and IgE), fasting blood glucose and other potential confounders. The subjects were divided into four groups from Q1 to Q4 according to the quartiles of baseline immunoglobulin concentration. The multivariable Cox regression model was used to assess the association between the baseline immunoglobulin concentration and T2DM. Results: A total of 6 315 subjects aged (50.1±10.0) years were included. About 390 subjects were newly diagnosed with T2DM during the follow-up period. The incidence rate was 16.8/1 000 person-years. After adjusting for age, sex, waist circumference, smoking status, drinking status, eosinophil ratio, metabolic syndrome, first-or second-degree family history, and reciprocal adjusting for other immunoglobulin concentrations, compared to the lowest quartile concentration group Q1, subjects in group Q4 with the highest quartile of IgG concentration showed a lower risk of T2DM (HR=0.71, 95%CI: 0.52-0.97), and subjects in group Q4 with the highest quartile of IgM concentration also had a decreased risk of T2DM (HR=0.66, 95%CI: 0.47-0.91). Subjects in group Q4 with the highest quartile of IgA concentration had an increased risk of T2DM (HR=1.56, 95%CI: 1.18-2.07). The risk of T2DM decreased with the increase of serum IgG and IgM concentrations (Ptrend=0.018, Ptrend=0.010) and increased with the increase of serum IgA concentrations (Ptrend<0.001). No association was found between the concentration of IgE and T2DM risk (HR=0.99, 95%CI: 0.74-1.31, Ptrend=0.891). Conclusion: The concentration of IgG and IgM is negatively associated with the risk of T2DM, and the concentration of IgA is positively associated with the risk of T2DM in Tianjin City. The concentrations of IgG, IgM and IgA could be a predictor of hyperglycemia and T2DM.

[Associations between internet addiction, screen time and depressive symptoms]

Objective: To understand the associations between internet addiction, screen time (computer/mobile devices use and television watching time) and depressive symptoms in adults. Methods: A total of 6 932 adults aged <60 years from the Tianjin Chronic Low-grade Sgstemic Inflammation and Health (TCLSIH) Cohort of 2013-2019 were surveyed. The information about their computer/mobile devices use and television watching time were collected by using a self-reported questionnaire. The depressive symptoms were assessed using the self-rating depression scale (SDS). The adults surveyed were divided into two groups: non-depressive symptom group (SDS score <45) and depressive symptom group (SDS score ≥45). The associations between internet addiction, screen time and depressive symptoms were estimated using Cox proportional hazard regression models, with adjusting for multiple confounders. Results: After adjusting for confounding factors, the hazard ratios (HRs) of depressive symptom in the adults who had internet addiction before, had light internet addiction and had moderate or severe internet addiction were 0.83 (95%CI: 0.56-1.23) , 1.20 (95%CI: 1.03-1.41) for light and 1.48 (95%CI: 1.16-1.89), respectively, compared with those without internet addiction. The linear trend test results of the association between internet addiction and depressive symptoms was significant (trend P<0.001). Compared with the adults who used computer/mobile devices for <1 hour/day, the HRs of depressive symptoms in those who used computer/mobile devices for >1 hour, >3 hours, >5 hours and >10 hours were 0.59 (95%CI: 0.40-0.88), 0.58 (95%CI: 0.40-0.85), 0.52 (95%CI: 0.36-0.76) and 0.69 (95%CI: 0.45-1.05) respectively, a U-shaped association was found between computer/mobile devices use time and depressive symptoms (trend P<0.001). Compared with the adults who never watch TV, the HR of depressive symptoms was 1.36 (95%CI:1.09-1.69) for those watching TV for ≥3 hours/day in crude model and 1.34 (95%CI: 1.07-1.68) for those watching TV for ≥3 hours/day in adjusted model (trend P<0.001). Conclusion: Our findings suggested that internet addiction and television watching time were associated with an increased risk of depressive symptoms, while computer/mobile device use time was associated with a reduced risk of depressive symptoms.

[Autopsies and placental examinations of perinatal fetal deaths: a clinicopathological analysis of 105 cases]

Objective: To summarize the clinicopathological factors related to perinatal fetal death and to evaluate importance of fetal autopsy and placental pathology. Methods: The clinicopathological data of 105 perinatal fetal deaths in Beijing Haidian Maternal and Child Health Hospital from November 2012 to December 2020 were retrospectively analyzed. Relevant literature was also reviewed. Results: The maternal age of the deceased fetuses ranged from 22 to 43 years with the average (31.35±4.04 years), and the gestational weeks were 28-40⁺⁶ weeks. Among them, 101 were singleton cases and 4 twin cases. 103 fetuses died in uterus and 2 died during delivery. Relevant factors analysis of the 105 perinatal fetal deaths showed that 86 cases (81.9%, 86/105) were related to umbilical cord/placental abnormality, 10 cases (9.5%, 10/105) uterine infection, 6 cases (5.7%, 6/105) fetal factors, 1 case was fetal maternal blood transfusion syndrome, 1 case twin blood transfusion syndrome, and 1 case died of complete uterine rupture. Among the 86 cases related to umbilical cord/placental abnormality, the diagnosis was most often based on the gross examination of placenta. The most common cause of death was umbilical cord torsion with thin root, followed by placental abruption, tight umbilical cord winding, vascular rupture and umbilical cord true knot. The morphology of placenta revealed mainly functional changes. Among the 10 cases related to intrauterine infections, the placenta generally showed lobular placental edema. The morphological characteristics of ascending infection were mainly acute chorioamnionitis, and the morphological characteristics of blood-borne infection were mainly acute or chronic villitis, as well as villous interstitial inflammation. Identification of viral inclusions suggested viral etiology, while the final diagnosis was relied on laboratory testing. Among the 6 cases related to fetal abnormality, the diagnostic value of placenta was limited and the diagnosis could be made with fetal autopsy. Conclusion: The causes of perinatal fetal death are complex, diverse, and often the synergistic result of multiple factors. Fetal autopsy and placental pathology are the key technical means to identify the cause of death and deserve more attention and utilization.

[Singleton placentas with abnormal shape: a clinicopathological analysis of 130 cases]

Objective: To investigate the pathological characteristics of singleton placenta with abnormal shape and its influence on the outcome of maternal-fetal pregnancy. Methods: The clinicopathological data of singleton placentas with abnormal shape from January 2014 to December 2020 in the Department of Pathology, Haidian Maternal and Children Health Hospital were analyzed retrospectively. Results: There were 130 singleton placentas with abnormal shape in this cohort, including 48 succenturiate placentas, 12 bilobed placentas, 50 marginate placentas, 13 circumvallate placentas, 3 annular placentas, 2 membranous placentas and 2 fenestrated placentas. Gestational age ranged from 29⁺⁵ to 40⁺⁴ weeks. There were 51 cases of premature rupture of membranes, 11 cases of placenta previa, 5 cases of placental abruption, 15 cases of placental adhesion/implantation and 27 cases of postpartum hemorrhage. There were 46 preterm fetuses,28 fetuses with fetal growth restriction, 22 fetuses with intrauterine distress, and 1 fetus with intrauterine death. Grossly, the placental lobules of succenturiate placentas had apparent size difference, while two lobules of bilobate placenta were more consistent. The chorionic plate size was smaller than the bottom plate of circumvallate placenta, the folded fetal membrane in the rim of placenta was thickened (termed marginate placenta if there was no thickening). The membranous placenta was characterized by a thin, large membrane-like shape. Annular placenta showed characteristic hollow cylinder, ring or horseshoe-shape. Fenestrated placenta was characterized by tissue defects near central area. Microscopically, functional/morphologic changes were the main manifestations of inadequate maternal-fetal perfusion, including villous infarction, distal villous dysplasia and excessive villous maturation. Conclusions: The abnormal shaped singleton placentas showed variable extent of inadequate maternal-fetal perfusion, which may lead to adverse pregnancy outcomes such as premature delivery, fetal growth restriction, intrauterine distress or fetal death.

Expression of autophagy related genes in peripheral blood cells in Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder and affects dopaminergic neurons. Autophagy often shows a circadian rhythm pattern under physiological conditions across 24 h. Abnormal autophagy and circadian dysfunction are two characteristics of PD. Whether the rhythm of autophagy is altered in PD has not yet been reported. Therefore, in this study, we collected peripheral blood samples at 6:00 h and 18:00 h from PD patients and age-matched controls, and analyzed the mRNA expressions of ULK1, BECN1, LAMP2, AMPK, and SNCA using real-time quantitative PCR. Blood samples analysis found that BECN1 and LAMP2 levels were decreased in patients with PD. Simultaneously, the rhythm of autophagy in PD is not consistent with that in the Control group, which may be a manifestation of the abnormal biological rhythm of PD.

Endovascular and hybrid treatments for subclavian artery aneurysms

OBJECTIVE

This paper retrospectively reviews our experience with endovascular and hybrid treatments for subclavian artery aneurysms (SAA).

METHODS

Seventeen patients with SAAs were treated at our center between July 2011 and October 2018. Clinical and follow-up data were extracted from the hospital records and retrospectively reviewed. We routinely use endovascular treatments and stenting or axillary-axillary bypass to treat SAA if vertebral artery blood flow requires restoration. Patients were followed up at 3, 6, and 12 months after their operations and yearly thereafter.

RESULTS

Median follow-up was 30.5 months. In 6 patients, the SAAs involved the ipsilateral vertebral artery. Simple coil embolization was performed for 1 patient; endovascular covered stenting and coil embolization for 4 patients; and hybrid treatment for 1 patient. In 11 patients, the SAAs did not involve the ipsilateral vertebral artery. Hybrid treatment was performed for 1 patient; thoracic aortic stent implantation with coil embolization for 1 patient; and covered stent placement in the subclavian artery for 9 patients. Among the 9 patients who were symptomatic at presentation, 8 had relief of symptoms. Leakage was observed in 1 patient, but it stopped spontaneously. Stent occlusion occurred in 18.8% (3/16), but all were asymptomatic, and no interventions were necessary.

CONCLUSION

Endovascular and hybrid treatments appear to be effective for SAAs with few complications and good clinical outcomes.

KEY WORDS

Covered stent, Coil embolization, Endovascular treatment, Hybrid, Subclavian artery aneurysm.

[Method of dietary nutritional status assessment and its application in cohort study of nutritional epidemiology]

Minimizing the burden on study subjects and assessing the general dietary nutritional status as accurately as possible are the basis of a nutritional epidemiological cohort study in the general population. While introducing the main dietary nutrition assessment methods, this paper manly describes the basic contents and principles for the development of food frequency questionnaire, and briefly illustrates the problems and solutions for the development of area specific food frequency questionnaires by taking the example of Tianjin Chronic Low-grade Systemic Inflammation and Health (TCLSIH) cohort study. Finally, discusses preliminarily the necessity and possibility of developing a national food frequency questionnaire.

[Prognosis analysis of 112 cases with Japanese encephalitis in adults]

Objective: To analyze the improvement of clinical symptoms and recovery of neurological function in adult Japanese encephalitis, and study the prognostic factors. Methods: Follow-up was conducted for 112 hospitalized patients with Japanese encephalitis (JE) in adults at the Department of Neurology of three hospitals in Gansu province from July to October 2016, from July to October 2017, 6 months and 1 year after onset, respectively. The neurological functional recovery was evaluated by modified Ranking Scale (mRS).The influencing factors were analyzed by logistic regression model. Results: Among the 112 adult patients with JE after 1year follow-up, 57% (64/112) were completely recovered (mRS score=0), and 14%(16/112) had mild neurological dysfunction (mRS score=1 or 2 points), 20% (22/112) had moderate to severe neurological dysfunction (mRS score 3 to 5), and 9% (10/112) died. In 102 survivors, decreased consciousness were fully recovered (100%), 75% of the mental and behavior disorders, 64% of cognitive/memory impairment, 71% of language function disorder, 61% of paralysis, 73% of extrapyramidal symptoms were fully recovered, and 92% of the seizures were controlled. Comparison of clinical data of initial on-set between good prognosis group (mRS score≤2, 80 cases) and poor prognosis group (mRS score>2, 32 cases) showed that initial clinical manifestation with seizures, consciousness (GCS score), cerebrospinal fluid pressure, and lesion of MRI involved in midbrain had statistically significant differences (all P<0.05) . Multivariate analysis demonstrated that cerebrospinal fluid (CSF) pressure>250 mmH(2)O and lesion of midbrain in MRI were independent risk factors of poor prognosis in adult patients with JE. Conclusion: JE is an acute and infectious viral encephalitis of the central nervous system with high disability and mortality. Most patients were completely recovered, and some had neurological sequelae. CSF pressure>250 mmH(2)O and lesion of midbrain in MRI are independent risk factors for poor prognosis.

Aspiration therapy for acute embolic occlusion of the superior mesenteric artery

BACKGROUND

Embolic superior mesenteric artery (SMA) occlusion is associated with high mortality rates. Delayed treatment often leads to serious consequences, including intestinal necrosis, resection, and even patient death. Endovascular repair is being introduced, which can improve clinical symptoms and prognosis and decrease the incidence of exploratory laparotomy. Many reports have described successful endovascular revascularization of embolic SMA occlusion. However, most of those reports are case reports, and there are few reports on Chinese patients. In this paper, we describe the technical and clinical outcomes of aspiration therapy using a guiding catheter and long sheath technique which facilitates the endovascular repair procedure.

AIM

To evaluate the complications, feasibility, effectiveness, and safety of endovascular treatment for the acute embolic occlusion of the SMA.

METHODS

This retrospective study reviewed eight patients (six males and two females) from August 2013 to October 2018 at Xuanwu Hospital, Capital Medical University. The patients presented with acute embolic occlusion of the SMA on admission and were initially diagnosed by computed tomography angiography (CTA). The patients who underwent endovascular treatment with a guiding catheter had no obvious evidence of bowel infarct. No intestinal necrosis was identified by gastrointestinal surgeons through peritoneal puncture or CTA. The complications, feasibility, effectiveness, safety, and mortality were assessed.

RESULTS

Six (75%) patients were male, and the mean patient age was 70.00 ± 8.43 years (range, 60-84 years). The acute embolic occlusion of the SMA was initially diagnosed by CTA. All patients had undertaken anticoagulation primarily, and percutaneous aspiration using a guiding catheter was then undertaken because the emboli had large amounts of thrombus residue. No death occurred among the patients. Complete patency of the suffering artery trunk was achieved in six patients, and defect filling was accomplished in two patients. The in-hospital mortality was 0%. The overall 12-mo survival rate was 100%. All patients survived, and two of the eight patients had complications (the clot broke off during aspiration).

CONCLUSION

Aspiration therapy is feasible, safe, and beneficial for acute embolic SMA occlusion. Aspiration therapy has many benefits for reducing patients’ death, resolving thrombi, and improving symptoms.

Towards high-energy, high-resolution computed tomography via a laser driven micro-spot gamma-ray source

Computed Tomography (CT) is a powerful method for non-destructive testing (NDT) and metrology awakes with expanding application fields. To improve the spatial resolution of high energy CT, a micro-spot gamma-ray source based on bremsstrahlung from a laser wakefield accelerator was developed. A high energy CT using the source was performed, which shows that the resolution of reconstruction can reach 100 μm at 10% contrast. Our proof-of-principle demonstration indicates that laser driven micro-spot gamma-ray sources provide a prospective way to increase the spatial resolution and toward to high energy micro CT. Due to the advantage in spatial resolution, laser based high energy CT represents a large potential for many NDT applications.

Experimental Evidence of Kinetic Effects in Indirect-Drive Inertial Confinement Fusion Hohlraums

We present the first experimental evidence supported by simulations of kinetic effects launched in the interpenetration layer between the laser-driven hohlraum plasma bubbles and the corona plasma of the compressed pellet at the Shenguang-III prototype laser facility. Solid plastic capsules were coated with carbon-deuterium layers; as the implosion neutron yield is quenched, DD fusion yield from the corona plasma provides a direct measure of the kinetic effects inside the hohlraum. An anomalous large energy spread of the DD neutron signal (∼282  keV) and anomalous scaling of the neutron yield with the thickness of the carbon-deuterium layers cannot be explained by the hydrodynamic mechanisms. Instead, these results can be attributed to kinetic shocks that arise in the hohlraum-wall-ablator interpenetration region, which result in efficient acceleration of the deuterons (∼28.8  J, 0.45% of the total input laser energy). These studies provide novel insight into the interactions and dynamics of a vacuum hohlraum and near-vacuum hohlraum.

Efficacy, safety and influencing factors of intra-calf muscular injection of bone marrow mononuclear cells in the treatment of type 2 diabetes mellitus-induced lower extremity vascular disease

The efficacy, safety and impact of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) associated with the intra-calf muscular injection of bone marrow mononuclear cells (BMMCs) in the treatment of type 2 diabetes mellitus (T2DM)-induced lower extremity vascular disease (LEVD) were evaluated. Patients with T2DM-LEVD were randomly divided into a control group and BMMCs group to assess the efficacy and safety of the treatment; serum VEGF and bFGF levels were detected. The BMMCs group was divided into superior genicular artery (SGA) and inferior genicular artery (IGA) subgroups as well as low-dose and high-dose subgroups for the comparison of efficacy indices. The BMMCs group exhibited significantly improved indices (P<0.05) compared with the control group and no fatalities or cancer occurred. There were no significant changes in serum VEGF and bFGF levels (P>0.05). The claudication distance in the IGA subgroup was significantly greater that in the SGA subgroup (P<0.05); the low-dose subgroup and the high-dose subgroup did not demonstrate any significant differences in each index (P>0.05). BMMC treatment for T2DM-LEVD was found to be safe and effective and had no significant impact on serum VEGF and bFGF levels in the short term; However, the degree of LEVD may affect its efficacy.

Femtosecond Probing of Plasma Wakefields and Observation of the Plasma Wake Reversal Using a Relativistic Electron Bunch

We show that a high-energy electron bunch can be used to capture the instantaneous longitudinal and transverse field structures of the highly transient, microscopic, laser-excited relativistic wake with femtosecond resolution. The spatiotemporal evolution of wakefields in a plasma density up ramp is measured and the reversal of the plasma wake, where the wake wavelength at a particular point in space increases until the wake disappears completely only to reappear at a later time but propagating in the opposite direction, is observed for the first time by using this new technique.

Endovascular repair of subclavian artery aneurysms: results from a single-center experience

Objective:

To present our experience of the endovascular treatment of subclavian artery aneurysms (SAAs) and analyze the clinical manifestations, imaging findings and treatment outcomes.

Methods:

In this retrospective study, nine patients with SAAs underwent endovascular stent placement in our center between July 2011 and June 2016. Clinical features, imaging findings, treatment outcomes and follow-up results of these SAA patients were retrospectively analyzed.

Results:

Nine patients were diagnosed with SAAs by computer tomography angiography (CTA). Five patients underwent percutaneous endovascular stent placement in the subclavian artery. Three patients underwent endovascular repair of the SAAs with coil embolization and stent graft. One patient underwent stent graft implantation by the simultaneous kissing stent technique. Five patients had their symptoms relieved and thrombosis occurred in one case. The mean follow-up period was 17 months, ranging from 8 to 40 months.

Conclusion:

For patients with SAAs, endovascular treatment is a feasible choice, with a high success rate, few complications and good clinical outcomes.

Establishment and evaluation of a reversible two-kidney, one-clip renovascular hypertensive rat model

The aim of the present study was to establish and evaluate a novel and reversible two-kidney, one-clip renovascular hypertensive rat model with a titanium vascular clip. A total of 40 male Sprague-Dawley rats were evenly and randomly divided into a sham-operated group, and 3, 7, 12 and 28D groups (namely removing the vascular clip in the renovascular hypertensive model after 3, 7, 12 and 28 days, respectively). The systolic blood pressure (SBP) and plasma renin activity (PRA) were measured, and color duplex imaging was conducted before placing the clips, as well as before and after removing them. After placing the vascular clips, SBP and PRA in the 3, 7, 12 and 28D groups were significantly increased (SBP: Sham-operated vs. 3D groups, P=0.020; 3 vs. 7D groups, P=0.008; 7 vs. 28D groups, P=0.019; 12 vs. 28D groups, P=0.039, and between other groups P<0.001. PRA: 3 vs. 7D groups, P=0.001; 7 vs. 12D groups, P=0.004; 12 vs. 28D groups, P=0.040, and between other groups, P<0.001). After removing the clips, SBP were significantly reduced in the 3 and 7D groups (P=0.023, 0.040, 0.066 and 0.314 in the 3, 7, 12 and 28D groups, respectively), but were still significantly higher than that before placing clips in the 7, 12 and 28D groups (P=0.067, P=0.005, P<0.001 and P<0.001 in the 3, 7, 12 and 28D groups, respectively). After removing the clips, PRA was significantly reduced in each group (P<0.001, P<0.001, P=0.012 and P=0.049 in 3, 7, 12 and 28D groups, respectively), but still higher than that before placing the clips (P<0.001, P=0.001, P=0.001 and P=0.003 in 3, 7, 12 and 28D groups, respectively). Vascular imaging also indicates this model has a reversible property. In conclusion, a reversible renovascular hypertension rat model is feasible, and provides a basis for research on clinical ischemic nephropathy and renal artery revascularization.

Brilliant petawatt gamma-ray pulse generation in quantum electrodynamic laser-plasma interaction

We show a new resonance acceleration scheme for generating ultradense relativistic electron bunches in helical motions and hence emitting brilliant vortical γ-ray pulses in the quantum electrodynamic (QED) regime of circularly-polarized (CP) laser-plasma interactions. Here the combined effects of the radiation reaction recoil force and the self-generated magnetic fields result in not only trapping of a great amount of electrons in laser-produced plasma channel, but also significant broadening of the resonance bandwidth between laser frequency and that of electron betatron oscillation in the channel, which eventually leads to formation of the ultradense electron bunch under resonant helical motion in CP laser fields. Three-dimensional PIC simulations show that a brilliant γ-ray pulse with unprecedented power of 6.7 PW and peak brightness of 10²⁵ photons/s/mm²/mrad²/0.1% BW (at 15 MeV) is emitted at laser intensity of 1.9 × 10²³ W/cm².

Large-charge quasimonoenergetic electron beams produced by off-axis colliding laser pulses in underdense plasma

Electrons can be efficiently injected into a plasma wave by colliding two counterpropagating laser pulses in a laser wakefield acceleration. However, the generation of a high-quality electron beam with a large charge is difficult in the traditional on-axis colliding scheme due to the growth of the electron beam duration coming from the increase of the beam charge. To solve this problem, we propose an off-axis colliding scheme, in which the collision point is away from the axis of the driver pulse. We show that the electrons injected from the off-axis region are highly concentered on the tail of the bubble even for a large trapped charge, thus feeling almost the same accelerating field. As a result, quasimonoenergetic electron beams with a large charge can be produced. The validity of this scheme is confirmed by both the particle-in-cell simulations and the Hamiltonian model. Furthermore, it is shown that a Laguerre-Gauss (LG) laser can be adopted as the injection pulse to realize the off-axis colliding injection in three dimensions symmetrically, which may be useful in simplifying the technical layout of the real experiment setup.

Physical Mechanism of the Transverse Instability in Radiation Pressure Ion Acceleration

The transverse stability of the target is crucial for obtaining high quality ion beams using the laser radiation pressure acceleration (RPA) mechanism. In this Letter, a theoretical model and supporting two-dimensional (2D) particle-in-cell (PIC) simulations are presented to clarify the physical mechanism of the transverse instability observed in the RPA process. It is shown that the density ripples of the target foil are mainly induced by the coupling between the transverse oscillating electrons and the quasistatic ions, a mechanism similar to the oscillating two stream instability in the inertial confinement fusion research. The predictions of the mode structure and the growth rates from the theory agree well with the results obtained from the PIC simulations in various regimes, indicating the model contains the essence of the underlying physics of the transverse breakup of the target.

Improved spatial calibration for the CXRS system on EAST

A Charge eXchange Recombination Spectroscopy (CXRS) diagnostic system has been developed to measure profiles of ion temperature and rotation since 2014 on EAST. Several techniques have been developed to improve the spatial calibration of the CXRS diagnostic. The sightline location was obtained by measuring the coordinates of three points on each sightline using an articulated flexible coordinate measuring arm when the vessel was accessible. After vacuum pumping, the effect of pressure change in the vacuum vessel was evaluated by observing the movement of the light spot from back-illuminated sightlines on the first wall using the newly developed articulated inspection arm. In addition, the rotation of the periscope after vacuum pumping was derived by using the Doppler shift of neutral beam emission spectra without magnetic field. Combining these techniques, improved spatial calibration was implemented to provide a complete and accurate description of the EAST CXRS system. Due to the effects of the change of air pressure, a ∼0.4° periscope rotation, yielding a ∼20 mm movement of the major radius of observation positions to the lower field side, was derived. Results of Zeeman splitting of neutral beam emission spectra with magnetic field also showed good agreement with the calibration results.

Identification of new single nucleotide polymorphisms affecting total number born and candidate genes related to ovulation rate in Chinese Erhualian pigs

The Chinese Erhualian pig has the highest record for litter size in the world. However, the genetic mechanism of its high prolificacy remains poorly understood. In our study, large phenotypic variations in litter size were found among Erhualian sows. Significant differences in total number born (TNB) and corpora lutea numbers were observed between sows with high and low estimated breeding values (EBVs) for TNB. To identify single nucleotide polymorphisms (SNPs) associated with TNB, a selective genomic scan was conducted on 18 sows representing the top 10% and 18 sows representing the bottom 10% of EBVs of 177 sows using Illumina Porcine SNP60 genotype data. Genome-wide fixation coefficient (F_ST ) values were calculated for each SNP between the high- and low-EBV groups. A total of 154 SNPs were significantly differentiated loci between the two groups. Of the top 10 highest F_ST SNPs, rs81399474, rs81400131 and rs81405013 on SSC8 and rs81434499 and rs81434489 on SSC 12 corresponded to previously reported QTL for litter size. The other five SNPs, rs81367039 on SSC2, rs80891106 on SSC7, rs81477883 on SSC12 and rs80938898 and rs80971725 on SSC14, appeared to be novel QTL for TNB. Significant associations between rs81399474 on SSC8 and TNB were confirmed in 313 Erhualian sows. Forty genes were identified around the top 10 highest F_ST SNPs, of which UCHL1, adjacent to rs81399474, and RPS6KB1 and CLTC, adjacent to rs81434499, have been reported to affect the ovulation rate in pig. The findings can advance understanding of the genetic variations in litter size of pigs.

Capturing relativistic wakefield structures in plasmas using ultrashort high-energy electrons as a probe

A new method capable of capturing coherent electric field structures propagating at nearly the speed of light in plasma with a time resolution as small as a few femtoseconds is proposed. This method uses a few femtoseconds long relativistic electron bunch to probe the wake produced in a plasma by an intense laser pulse or an ultra-short relativistic charged particle beam. As the probe bunch traverses the wake, its momentum is modulated by the electric field of the wake, leading to a density variation of the probe after free-space propagation. This variation of probe density produces a snapshot of the wake that can directly give many useful information of the wake structure and its evolution. Furthermore, this snapshot allows detailed mapping of the longitudinal and transverse components of the wakefield. We develop a theoretical model for field reconstruction and verify it using 3-dimensional particle-in-cell (PIC) simulations. This model can accurately reconstruct the wakefield structure in the linear regime, and it can also qualitatively map the major features of nonlinear wakes. The capturing of the injection in a nonlinear wake is demonstrated through 3D PIC simulations as an example of the application of this new method.

Prospective Randomized Study of Sarpogrelate Versus Clopidogrel-based Dual Antiplatelet Therapies in Patients Undergoing Femoropopliteal Arterial Endovascular Interventions: Preliminary Results

Background:

Sarpogrelate is a selective 5-hydroxytryptamine (5-HT) receptor subtype 2A antagonist which blocks 5-HT induced platelet aggregation and proliferation of vascular smooth muscle cells. We compared the efficacy of sarpogrelate-based dual antiplatelet therapies for the prevention of restenosis and target lesion revascularization (TLR) rates comparing with that of clopidogrel after percutaneous endovascular interventions (EVIs) of femoropopliteal (FP) arterial lesions.

Methods:

This prospective, multicenter, randomized clinical trial recruited a total of 120 patients with successful EVI of FP lesions at seven centers across China between January 2011 and June 2012. Patients were randomized to receive either sarpogrelate (100 mg trice daily for 6 months, n = 63) or clopidogrel (75 mg once daily for 6 months, n = 57). All patients also received oral aspirin (100 mg once daily for 12 months). Clinical follow-up was conducted up to 12 months postprocedure.

Results:

There was no significant difference between the two groups in basic demographic data. The restenosis rate was higher in the clopidogrel group (22.80%) than in sarpogrelate group (17.50%), but there was no significant difference between these two groups (P = 0.465). The TLR rate, ipsilateral amputation rate, mortality in all-cause and bleeding rate were also similar in the two groups (P > 0.05).

Conclusions:

Aspirin plus sarpogrelate is a comparable antithrombotic regimen to aspirin plus clopidogrel after EVI of FP arterial lesions. Dual antiplatelet therapies might play an important role in preventing restenosis after successful EVI of FP lesions.

Evaluation in vivo of autologous cell derived vein grafts based on tissue engineering concept

AIM

Aim of the study was to construct and evaluate of autologous cell derived vein grafts based on tissue engineering concept.

METHODS

In this study, we constructed venous grafts (VGs) in 12 days based on tissue engineering concept. We draw out 8-12 mL of bone marrow from the intended recipient canines (N.=8) to culture and expand endothelial progenitor cells (EPCs). After having been labeled with PKH26-GL, the cells were seeded onto the luminal surface of decellularized scaffolds (DSs) with single, rotative method for 4 hours. Following static culture for 24-72 hours, the hybrids were implanted to recipient canine inferior vena cava. Non-seeded DSs (N.=4) were performed as control.

RESULTS

Angiography disclosed that patent number of test (control) group were 7/7 (2/4), 6/6 (2/2) and 4/4 (1/2) at postoperative 10 days, 4 weeks and 12 weeks, respectively. At 12 weeks, confluenced endothelial cells which covered the whole inner luminal surface of the explants were detected. Meanwhile, fibroblasts and α-actin positive cells in the matrices were found. PKH26-GL labeled EPCs sustained on the luminal surface accompanied by newly formed endothelial cells. However, the explants in both groups showed partial stenosis.

CONCLUSION

These results indicate that such constructed VGs based on autologous bone marrow-derived EPCs and porcine DSs are promising and deserve to further improvement and testing.

The fabrication of double layer tubular vascular tissue engineering scaffold via coaxial electrospinning and its 3D cell coculture

A continuous electrospinning technique was applied to fabricate double layer tubular tissue engineering vascular graft (TEVG) scaffold. The luminal layer was made from poly(ɛ-caprolac-tone)(PCL) ultrafine fibers via common single axial electrospinning followed by the outer layer of core-shell structured nanofibers via coaxial electrospinning. For preparing the outer layernano-fibers, the PCL was electrospun into the shell and both bovine serum albumin (BSA) and tetrapeptide val-gal-pro-gly (VAPG) were encapsulated into the core. The core-shell structure in the outer layer fibers was observed by transmission electron microscope (TEM). The in vitro release tests exhibited the sustainable release behavior of BSA and VAPG so that they provided a better cell growth environment in the interior of tubular scaffold wall. The in vitro culture of smooth muscle cells (SMCs) demonstrated their potential to penetrate into the scaffold wall for the 3D cell culture. Subsequently, 3D cell coculture was conducted. First, SMCs were seeded on the luminal surface of the scaffold and cultured for 5 days, and then endothelial cells (ECs) were also seeded on the luminal surface and cocultured with SMCs for another 2 days. After stained with antibodies, 3D cell distribution on the scaffold was revealed by confocal laser scanning microscopy (CLSM) where ECs were mainly located on the luminal surface whereas SMCs penetrated into the surface and distributed inside the scaffold wall. This double layer tubular scaffold with 3D cell distribution showed the promise to develop it into a novel TEVG for clinical trials in the near future.

Experimental study on the construction of small three-dimensional tissue engineered grafts of electrospun poly-ε-caprolactone

Studies on three-dimensional tissue engineered graft (3DTEG) have attracted great interest among researchers as they present a means to meet the pressing clinical demand for tissue engineering scaffolds. To explore the feasibility of 3DTEG, high porosity poly-ε-caprolactone (PCL) was obtained via the co-electrospinning of polyethylene glycol and PCL, and used to construct small-diameter poly-ε-caprolactone-lysine (PCL-LYS-H) scaffolds, whereby heparin was anchored to the scaffold surface by lysine groups. A variety of small-diameter 3DTEG models were constructed with different PCL layers and the mechanical properties of the resulting constructs were evaluated in order to select the best model for 3DTEGs. Bone marrow mononuclear cells were induced and differentiated to endothelial cells (ECs) and smooth muscle cells (SMCs). A 3DTEG (labeled '10-4%') was successfully produced by the dynamic co-culture of ECs on the PCL-LYS-H scaffolds and SMCs on PCL. The fluorescently labeled cells on the 3DTEG were subsequently observed by laser confocal microscopy, which showed that the ECs and SMCs were embedded in the 3DTEG. Nitric oxide and endothelial nitric oxide synthase assays showed that the ECs behaved normally in the 3DTEG. This study consequently provides a new thread to produce small-diameter tissue engineered grafts, with excellent mechanical properties, that are perfusable to vasculature and functional cells.

Meso-cavo-jugular shunt for complicated portal hypertension: a case report with 8 years of follow-up

BACKGROUND

The treatment of portal hypertension caused by an occlusive lesion in the retrohepatic inferior vena cava and terminal portal venules is complicated because both portal and system venous flow are compromised.

METHODS

A 47-year-old woman presented with this issue, and we reasoned that the only way to achieve successful management was to create a meso-cavo-jugular shunt. This patient was referred to us after undergoing a splenectomy for hypersplenism, which made her ascites intractable. She had a retrohepatic vena caval stenosis and noncirrhotic portal hypertension. Percutaneous transluminal angioplasty of the inferior vena cava stenosis failed. She underwent substernal placement of a 14-mm ringed GoreTex graft (WL Gore and Associates, Flagstaff, AZ) with end-to-side connections to the superior mesenteric vein, internal jugular vein, and vena cava.

RESULT

Her ascites resolved, and at follow-up 8 years later her graft was patent.

CONCLUSION

The meso-cavo-jugular shunt can simultaneously decompress both portal and systemic venous systems and is worth considering in the rare circumstance of suprahepatic vena caval obstruction coupled with occlusion of the portal venules.

Sequence organization and evolutionary dynamics of Brachypodium-specific centromere retrotransposons

Brachypodium distachyon is a wild annual grass belonging to the Pooideae, more closely related to wheat, barley, and forage grasses than rice and maize. As an experimental model, the completed genome sequence of B. distachyon provides a unique opportunity to study centromere evolution during the speciation of grasses. Centromeric satellite sequences have been identified in B. distachyon, but little is known about centromeric retrotransposons in this species. In the present study, bacterial artificial chromosome (BAC)-fluorescence in situ hybridization was conducted in maize, rice, barley, wheat, and rye using B. distachyon (Bd) centromere-specific BAC clones. Eight Bd centromeric BAC clones gave no detectable fluorescence in situ hybridization (FISH) signals on the chromosomes of rice and maize, and three of them also did not yield any FISH signals in barley, wheat, and rye. In addition, four of five Triticeae centromeric BAC clones did not hybridize to the B. distachyon centromeres, implying certain unique features of Brachypodium centromeres. Analysis of Brachypodium centromeric BAC sequences identified a long terminal repeat (LTR)-centromere retrotransposon of B. distachyon (CRBd1). This element was found in high copy number accounting for 1.6 % of the B. distachyon genome, and is enriched in Brachypodium centromeric regions. CRBd1 accumulated in active centromeres, but was lost from inactive ones. The LTR of CRBd1 appears to be specific to B. distachyon centromeres. These results reveal different evolutionary events of this retrotransposon family across grass species.

Generating high-brightness electron beams via ionization injection by transverse colliding lasers in a plasma-wakefield accelerator

The production of ultrabright electron bunches using ionization injection triggered by two transversely colliding laser pulses inside a beam-driven plasma wake is examined via three-dimensional particle-in-cell simulations. The relatively low intensity lasers are polarized along the wake axis and overlap with the wake for a very short time. The result is that the residual momentum of the ionized electrons in the transverse plane of the wake is reduced, and the injection is localized along the propagation axis of the wake. This minimizes both the initial thermal emittance and the emittance growth due to transverse phase mixing. Simulations show that ultrashort (~8 fs) high-current (0.4 kA) electron bunches with a normalized emittance of 8.5 and 6 nm in the two planes, respectively, and a brightness of 1.7×10(19) A rad(-2) m(-2) can be obtained for realistic parameters.

Surgical treatment of carotid body tumor: case report and literature review

Carotid body tumors (CBT) are rare chemical receptor tumors. We report nine cases of CBT who were diagnosed at our center during 2004 to 2008 with a literature review. Of these nine patients, eight underwent complete resection, one received palliative resection due to the malignant nature of the tumor, and the other one refused surgery. No perioperative mortality and stroke occurred. During a mean follow up of 2.2 years, no deaths related to CBT occurred. Surgical treatment for CBT is relatively safe. The surgeon should be careful to maintain the integrity of carotid artery, and prevent cerebral ischemia and cranial nerve injuries in order to improve outcome.

Electron bow-wave injection of electrons in laser-driven bubble acceleration

An electron injection regime in laser wake-field acceleration, namely electron bow-wave injection, is investigated by two- and three-dimensional particle-in-cell simulation as well as analytical model. In this regime electrons in the intense electron bow wave behind the first bubble catch up with the bubble tail and are trapped by the bubble finally, resulting in considerable enhancement of the total trapped electron number. For example, with the increase of the laser intensity from 2 × 10(19) to 1 × 10(20) W/cm(2), the electron trapping changes from normal self-injection to bow-wave injection and the trapped electron number is enhanced by two orders of magnitude. An analytical model is proposed to explain the numerical observation.

Note: Absolute calibration of two DRZ phosphor screens using ultrashort electron bunch

This article gives the absolute calibration of two types phosphor screens (DRZ) that were used to detect and characterize electron bunches driven by laser-plasma accelerator. The test was performed with picoseconds electron bunch at a radio frequency linear electron accelerator in Tsinghua University. The photons emitted from DRZ screens showed good linear responses to the charge of incident electron bunch and cosine angular distribution in space. An energy conversional efficiency of effective scintillant matter was also calculated.

Tunable radiation source by coupling laser-plasma-generated electrons to a periodic structure

Near-infrared radiation around 1000 nm generated from the interaction of a high-density MeV electron beam, obtained by impinging an intense ultrashort laser pulse on a solid target, with a metal grating is observed experimentally. Theoretical modeling and particle-in-cell simulation suggest that the radiation is caused by the Smith-Purcell mechanism. The results here indicate that tunable terahertz radiation with tens GV/m field strength can be achieved by using appropriate grating parameters.

Biological artificial vessel graft in distal arterial bypass for treating diabetic lower limb ischemia: a case report

A 68-year-old female patient was treated for unhealed ulcer in the fourth toe of the left foot. Clinical examinations identified severe stenosis of the proximal segment and occlusion of the distal segment of the left anterior tibial artery, and occlusion of the left posterior tibial artery and the peroneal artery. The proximal stenotic segment of the left anterior tibial artery was dilated, but the distal occlusive part failed to be re-canalized. Left anterior tibial artery to dorsal pedal artery bypass was performed on the patient with an epoxide-crosslinked, special radicals antigen-sealed, porcine-derived biological graft; debridement of the left 4th digiti pedis was also performed. Postoperation course was uneventful. The pulse of the left dorsal pedal artery was strong. The ankle brachial index (ABI) increased from 0.60 to 1.09. Warfarin and two antiplatelet drugs were given after the operation. Six months after operation, computed tomographic angiogram (CTA) identified the patent graft.

Gene space dynamics during the evolution of Aegilops tauschii, Brachypodium distachyon, Oryza sativa, and Sorghum bicolor genomes

Nine different regions totaling 9.7 Mb of the 4.02 Gb Aegilops tauschii genome were sequenced using the Sanger sequencing technology and compared with orthologous Brachypodium distachyon, Oryza sativa (rice), and Sorghum bicolor (sorghum) genomic sequences. The ancestral gene content in these regions was inferred and used to estimate gene deletion and gene duplication rates along each branch of the phylogenetic tree relating the four species. The total gene number in the extant Ae. tauschii genome was estimated to be 36,371. The gene deletion and gene duplication rates and total gene numbers in the four genomes were used to estimate the total gene number in each node of the phylogenetic tree. The common ancestor of the Brachypodieae and Triticeae lineages was estimated to have had 28,558 genes, and the common ancestor of the Panicoideae, Ehrhartoideae, and Pooideae subfamilies was estimated to have had 27,152 or 28,350 genes, depending on the ancestral gene scenario. Relative to the Brachypodieae and Triticeae common ancestor, the gene number was reduced in B. distachyon by 3,026 genes and increased in Ae. tauschii by 7,813 genes. The sum of gene deletion and gene duplication rates, which reflects the rate of gene synteny loss, was correlated with the rate of structural chromosome rearrangements and was highest in the Ae. tauschii lineage and lowest in the rice lineage. The high rate of gene space evolution in the Ae. tauschii lineage accounts for the fact that, contrary to the expectations, the level of synteny between the phylogenetically more related Ae. tauschii and B. distachyon genomes is similar to the level of synteny between the Ae. tauschii genome and the genomes of the less related rice and sorghum. The ratio of gene duplication to gene deletion rates in these four grass species closely parallels both the total number of genes in a species and the overall genome size. Because the overall genome size is to a large extent a function of the repeated sequence content in a genome, we suggest that the amount and activity of repeated sequences are important factors determining the number of genes in a genome.

Pulmonary toxicity in mice exposed to low and medium doses of water-soluble multi-walled carbon nanotubes

Carbon nanotubes (CNTs) are a class of new allotrope of carbon. Different functionalized CNTs may vary from their physical and chemical properties to the biological property. In this study, the toxicity of water-soluble taurine multi-walled CNTs (tau-MWNTs), raw MWNTs and positive control crystalline silicon dioxide particles on mouse lungs via intratracheal instillation (i.t.) was investigated. The dosages we used were 0.125, 0.25, 0.5 or 1 mg/kg of tau-MWNTs and raw MWNTs, and 1 mg/kg of silicon dioxide particles; Serum and lungs were collected at 1, 7, 14 or 28 days postexposure. The biochemical and cellular parameters were assessed, which include the ratio of the lung weight and body weight (lung indices), lactate dehydrogenase (LDH), alkaline phosphatase (ALP) and angiotensin converting enzyme (ACE) in serum, and malondialdehyde (MDA), reduced glutathione (GSH), total sulfhydryl group (TSH) in lung tissue homogenates as well as the hydroxyproline in lungs. The characteristic recovery of the lung injury at 28 days postexposure was examined by the assessment of LDH, ALP, lung indices, and histopathology. ACE, MDA, GSH, TSH and histopathological changes showed that tau-MWNTs were less toxic than the raw MWNTs. Histopathological and ultrastructural investigation indicated that the acute pulmonary inflammation in lungs alleviated after 7d postexposure, and were greatly recovered within 28d. Meanwhile, the entrapment of tau-MWNTs reduced greatly by the 28d postexposure. Whereas the heavier pathologic changes induced by raw MWNTs lasted 7 days more than that of tau-MWNTs. Notably, no occurrence of granulomas and fibrosis were found in this study both in the two CNTs samples through 28d postexposure. Silicon dioxide particles, on the contrary, produced more severe damage to lungs than CNTs did in lung index, as well as other biochemical and cellular parameters. These findings indicate that water-soluble tau-MWNTs in low and medium doses induce slight and recoverable pulmonary inflammation in mice, and are less toxic than the insoluble raw MWNTs.

Structure effects in angle-resolved high-order above-threshold ionization of molecules

We present energy-resolved angular distributions of photoelectrons generated in above-threshold ionization (ATI) of nonaligned diatomic molecules N2 and O2 in high-intensity short laser pulses, with emphasis on the most energetic part of the spectra. The angular distribution for photoelectrons with energy of 10U(p) (U(p): ponderomotive energy), i.e., the plateau cutoff in ATI spectra, is found to be broader in O2 than in N2. Resorting to the analyses from both an S-matrix theory and an intuitive semiclassical model, we attribute the observation to the effect of the ground state molecular orbital structure on high-energy electron emission in strong-field molecular ionization.

[Tissue engineering of vascular graft from decellularized arterial matrix and mesenchymal stem cells.]

OBJECTIVE

To investigate the method of constructing small-diameter vascular grafts from xenogenic decellularized arterial matrices and mesenchymal stem cells (MSCs).

METHODS

Porcine iliac arteries were decellularized by detergent and trypsin treatment. Histology, mechanical strength and porosity experiments were performed to evaluate the properties of decellularized matrices. MSCs were isolated from bone marrow of dogs and expanded ex vivo. Decellularized matrices were seeded with MSCs and further cultured in a pulsatile bioreactor. Morphological features of the tissue engineered grafts were assayed by HE staining and scanning electron microscopy.

RESULTS

After cell extraction, absence of cellular components and preservation of extracellular matrix were verified. Mechanical strength of decellularized matrices was slightly reduced compared with native arteries. Porosity of decellularized matrices was 94.9%. Decellularized matrices were successfully seeded with MSCs, which grew to a near-confluent monolayer under flow conditions and MSCs were highly elongated and oriented to the flow direction.

CONCLUSION

Small-diameter vascular grafts can be constructed by seeding MSCs onto xenogenic decellularized arterial matrices and culturing in a pulsatile bioreactor.

[Treatment of severe cerebral ischemia in Takayasu's disease with arterial reconstruction]

OBJECTIVE

To evaluate the effect of surgical bypass and to explore the role of transcranial doppler (TCD) during the bypass operation.

METHODS

From March 2003 to February 2008, sixteen patients (4 male and 12 female) with mean age of 32 years old and mean disease course of 7.5 years were treated by surgical procedures. The main clinical presentations were dizziness, headache, vertigo, and visional dysfunction. Variated degree of artery stenoses in the 4 arteries (bilateral carotid and vertebral arteries) were revealed by color doppler ultrasonography and DSA. Eight patients underwent aorto-bi-subclavian arteries prosthetic graft bypass. Three patients underwent aorto-bi-subclavian artery prosthetic graft bypass and graft-unilateral carotid artery bypass with autologous great saphenous vein. Three patients underwent aorta-unilateral subclavian artery-unilateral carotid artery prosthetic graft bypass. Two patients underwent aorta carotid artery bypass with autologous great saphenous vein, of which one patient underwent aortocoronary artery bypass simultaneously. Cerebral blood supply was monitored in 14 patients with transcranial doppler. Unilateral subclavian carotid and femoral carotid artery shunt was used respectively to avoid cerebral ischemia during operation in 2 patients.

RESULTS

Symptoms and signs of cerebral ischemia improved in all patients with effective rate of 100% apart from deflected tongue-protrusion in 3 patients which recovered in 2 weeks after operation. All patients survived and no symptoms recurred at the end of a 2.2 year's follow-up. Unfortunately, two patients developed aneurysm at the anastomosis within 4 years after operation.

CONCLUSIONS

Arterial reconstruction is an effective method for Takayasu's disease with severe cerebral ischemia. TCD monitoring plays an important role during the bypass operation. It can help to determine the revision of blood pressure and prevent postoperative brain reperfusion injury.

In vitro study of endothelial cells lining vascular grafts grown within the recipient's peritoneal cavity

A living-tissue conduit with strong mechanical properties was used to produce small-diameter vessels. To improve blood compatibility, a shear-resistant confluent monolayer endothelium was formed on the luminal surface of the conduit. Under mechanical stimulation induced by pulsatile flow in a bioreactor, abrupt high-flow shear stress of 15.3 +/- 4.6 dynes/cm2 was applied to endothelial cells (ECs) seeded onto the lumen of a living-tissue conduit after 2 days of static culture. Scanning electron microscopy images revealed that most of the ECs were washed off after 3 days of dynamic culture. When shear stress was increased stepwise from 1.5 +/- 0.8 to 15.3 +/- 4.6 dynes/cm2 and applied to the ECs, scanning electron microscopy images of the luminal surface revealed that the confluent monolayer ECs were highly elongated and oriented to the flow direction, similar to findings in natural arteries in vivo. The results indicated that in vitro flow conditions played a key role in determining the durability of the EC layer. Careful design of the bioreactor and careful selection of the culture conditions will greatly improve the chances of producing a useful anti-thrombogenic surface for tissue-engineered small-diameter vessels.

[Surface modification of vascular tissue engineering biomaterial by low temperature plasma with NH3, CO2 and O2]

OBJECTIVE

To study the biocompatibility of poly (hydroxybutyrate-hydroxyvalerate) (PHBV) modified by low temperature plasma with NH3, CO2, and O2 with canine Endothelial cells (ECs) and provide the better materials for blood vessel tissue engineering via surface modification.

METHODS

PHBV was modified by low temperature plasma with NH3, CO2, and O2, for 0, 5, 10, 20, and 30 min respectively, PHBV not modified was used as control group. The contact angle was measured. X-ray photoelectron spectroscopy was used to detect the surface elements. Canine endothelial cells (ECs) were cultured on the surface of PHBV and were stained with fluorescence isothiocyanate (FITC). Their morphological characteristics were observed with fluorescence microscopy, and the cell proliferation was detected with MTT assay.

RESULTS

The surface contents of carbon of the PHBV modified by low temperature plasma with O2 and CO2 were 63.75% and 69.72%, both lower than that before modification (77.97%). The surface contents of oxygen of the PHBV modified by low temperature plasma with O2 and CO2 were 30.72% and 28.48%, both higher than that before modification (21.74%). The surface content of nitrogen of the PHBV modified by low temperature plasma with NH3 was 3.25%, remarkably higher than that before modification (0). The contact angles of different modification groups, especially those of the 5 min groups, were all significantly smaller than that of the unmodified group (P < 0.05 or P < 0.01). Compared with the control group, the cytocompatibility was better in the low temperature plasma modified groups.

CONCLUSION

The surface of PHBV modified by low temperature plasma with NH3, CO2, and O2 has active groups and good biocompatibility, so the surface modification of low temperature plasma with NH3, CO2, and O2 can be a kind of effective method for the tissue engineering blood vessel.

[Preliminary in vivo evaluation of tissue engineered venous grafts fabricated based on endothelial progenitor cells]

OBJECTIVE

To explore the feasibility of the tissue engineered venous grafts (TEVGs) constructed in vitro based on canine autologous bone marrow-derived endothelial progenitor cells (EPCs) and porcine decellularized aortic scaffolds implanted into the canine inferior vena cava.

METHODS

To draw out a volume of 8 - 12 ml of bone marrow from the canine (n = 8), to culture and expand EPCs in vitro using conditioned medium. After labeled with a red fluorescent dye PKH26-GL, the cells were seeded onto the luminal surface of decellularized porcine scaffolds with single, rotative method for 4 h. Following static culture for 24 - 72 h, the hybrids were implanted to replace autologous canine inferior vena cava about 4 cm long. Meantime one femoral artery-venous shunt about 1 cm long was performed. The non-seeded decellularized scaffolds (n = 4) were performed the same as control. Angiography was performed and the hybrids were explanted for morphology and labeled cells' immuno-fluorescence examinations at postoperative 10 d, 4 weeks and 12 weeks, respectively.

RESULTS

The patent number of experiment (control) group were 7/7 (2/4), 6/6 (2/2) and 4/4 (1/2) at postoperative 10 d, 4 weeks and 12 weeks, respectively. At 12 weeks, tightly confluence endothelial cells which covered the whole inner luminal surface of the explants were detected by immunohistochemistry of factor VIII and scanning electron microscopy, while fibrin-based pseudo-intima was detected on the inner luminal surface of matrix in the solo patent dog from the control group. Meanwhile, fibroblasts and alpha-actin positive cells in the matrices were found by transmission electron microscopy and alpha-actin immunohistochemistry. PKH26-GL labeled EPCs sustained on the luminal surface at a rather proportion accompanied by newly formed endothelial cells. However, the explants in both groups showed partial stenosis.

CONCLUSIONS

Such constructed tissue engineered venous graft based on canine autologous bone marrow-derived endothelial progenitor cells and porcine decellularized aortic matrices is promising and deserve to further improvement and testing.