[Prevalence and intervention effect of arteriovenous graft stenosis].

Objective: To evaluate the prevalence, intervention methods and effect of arteriovenous graft (AVG) stenosis. Methods: The clinical data of patients who received AVG in the Blood Purification Center, the First Affiliated Hospital of Zhengzhou University from January 2018 to December 2022 were retrospectively analyzed. The patency rate, prevalence and intervention effect of AVG stenosis were analyzed. Results: A total of 475 patients aged (55.5±11.8) years were included, and there were 193 male cases (40.6%) and 282 female cases (59.4%). The patients were followed up for [M (Q1, Q3)] 19 (12, 30) months, and the primary, assisted primary and secondary patency were 14 (5, 27), 27 (13, 55), and 59 (33, 65) months, respectively. There were 799 access events which needed intervention, with a total standardized intervention rate of 0.90 per patient-year. Totally, 431(53.9%, 431/799) stenosis events occurred in 207 AVG. Among 422 AVG stenosis events with complete clinical data, 57.8% (244/422) were multi-site stenosis and 42.2% (178/422) were single-site stenosis. The most common sites of stenosis were graft-vein anastomosis (47.6%, 340/715), venous outflows (22.7%, 162/715), and puncture zone (20.0%, 143/715). In the 414 stenosis with intact follow-up data, 90.8% (376/414) were treated by balloon angioplasty, 8.5% (35/414) received covered stent insertion, and 0.7% (3/414) were intervened by open surgery. Clinical success rate was 98.1% (406/414). The primary patency time after endovascular treatment was 6 (4, 12) months. Covered stent significantly increased post-intervention primary patency time compared withballoon angioplasty [6 (3, 7) months vs 3 (1, 4) months, P=0.020]. Conclusions: Stenosis is the most common complication of AVG, and the most common sites are graft-vein anastomosis, venous outflows, and puncture zone. Intervention of AVG stenosis has a high clinical success rate, and a relatively low post-intervention patency. Covered stent insertion improves the post-intervention patency of AVG, which has a poor effect using balloon expansion.

[A cross-sectional survey on the types of antiviral treatment plans for patients with chronic hepatitis B].

Objective: To understand the current antiviral treatment status and various clinical types of treatment plans in Xiamen City so as to explore ways to improve and optimize the diagnosis and treatment standards for chronic hepatitis B. Methods: A cross-sectional survey method was used to study the antiviral treatment status and treatment plans for chronic hepatitis B patients who visited and were diagnosed in the Department of Infectious Diseases and Hepatology of all tertiary hospitals in Xiamen City at 0:00~23:59 on May 25, 2022. Results: A total of 665 cases were surveyed in this study, with an antiviral treatment rate of 81.2%(540/665). The antiviral treatment rate of patients who accorded with the current guidelines for antiviral treatment indications was 85.8%(507/591). The antiviral treatment rate for 362 outpatients was 72.9%(264/362). Among them, the antiviral treatment rates were 80.1%, 89.3%, and 25.0%(226/282, 25/28, 13/52), respectively, for patients diagnosed with chronic hepatitis B, hepatitis B cirrhosis, and hepatitis B surface antigen-carrying status. The treatment plan for all outpatient patients was mainly oral nucleos(t)ide analogues, accounting for 59.1%(214/362). The antiviral treatment rate for 303 inpatients was 91.1%(276/303). The various clinical types of antiviral therapy rates among all patients were 70%~95%. The antiviral treatment plan for inpatients was mainly based on pegylated interferon alpha treatment, accounting for 72.6%(220/303). Conclusion: Antiviral treatment for chronic hepatitis B in Xiamen City can still be strengthened to meet the current demand for expanding antiviral treatment indications. Antiviral treatment rates and various types of treatment plans differ between outpatients and inpatients; thus, further awareness and acceptance of the goal of improving antiviral therapy, especially in outpatients, and the possibility for a clinical cure based on pegylated interferon alpha treatment are needed to maximize the benefit to more patients.

Intriguing structures and magic sizes of heavy noble metal nanoclusters around size 55 governed by relativistic effect and covalent bonding.

Nanoclusters usually display exotic physical and chemical properties due to their intriguing geometric structures in contrast to their bulk counterparts. By means of first-principles calculations within density functional theory, we find that heavy noble metal PtN nanoclusters around the size N = 55 begin to prefer an open configuration, rather than previously reported close-packed icosahedron or core-shell structures. Particularly, for PtN, the widely supposed icosahedronal magic cluster is changed to a three-atomic-layered structure with D6h symmetry, which can be well addressed by our recently established generalized Wulff construction principle (GWCP). However, the magic number of PtN clusters around 55 is shifted to a new odd number of 57. The high symmetric three-layered Pt57 motif is mainly stabilized by the enhanced covalent bonding contributed by both spin-orbital coupling effect and the open d orbital (5d(9)6s(1)) of Pt, which result in a delicate balance between the enhanced Pt-Pt covalent bonding of the interlayers and negligible d dangling bonds on the cluster edges. These findings about PtN clusters are also applicable to IrN clusters, but qualitatively different from their earlier neighboring element Os and their later neighboring element Au. The magic numbers for Os and Au are even, being 56 and 58, respectively. The findings of the new odd magic number 57 are the important supplementary of the recently established GWCP.

Spatial distribution, movement, body damage, and feather condition of laying hens in a multi-tier system.

The welfare and health of laying hens in the multitier system raise concern in public. The flock distributions during feeding time at 51 and 89 wk were studied in a multitier system. Furthermore, the ultra-high frequency radio frequency identification (UHF RFID) equipment was used to identify the transition between tiers and time spent in each tier of 48 focal hens (12 hens from each tier-group of the multitier system) at 92 wk of age. The body weight, tibia size (length and width), body damage (comb and rear part), and feather condition (neck, breast, back, tail, cloaca, and wings) of focal hens from different tier-groups were further compared. The results showed that the spatial distribution in flocks changed from top to bottom with increasing age. The hens at 51 wk of age were mainly distributed in the 4th tier (19.6 ± 5.0% in 1st tier, 9.6 ± 1.1% in 2nd tier, 23.6 ± 2.9% in 3rd tier and 47.3 ± 2.6% in 4th tier), and hens at 89 wk of age were mainly distributed in the lower tiers (33.5 ± 1.5% in 1st tier, 31.9 ± 5.1% in 2nd tier, 15.7 ± 3.4% in 3rd tier and 16.6 ± 3.1% in 4th tier). The spatial distribution of hens at 89 wk of age was more even than that at 51 wk of age. At 92 wk of age, the proportion of time spent in original tier of 4 tier-groups was 91.0 ± 5.7%, 51.9 ± 5.7%, 59.0 ± 7.0% and 63.0 ± 6.7%, respectively. Focal hens preferred to stay in the original tier and spent significantly less time in other tiers (P < 0.05). There was no significant difference in body weight, body damage score, tibia width and partial feather scores (neck, breast, tail, and cloaca) of focal hens among 4 tier-groups (P > 0.05). However, focal hens from 1st tier had worse feather scores on wings and back, and shorter tibia length compared to other tiers suggesting that there were more lower ranking birds that located in lower tier to avoid competition, but had equal access to resource, which is good for their welfare and health. In summary, the overcrowding situation was improved near the end of the laying cycle in the multitier system, thereby mitigating the potential negative effects to the lower ranking hens and maintain a satisfactory level of welfare and health for laying hens near the end of the laying cycle.

Relative edge energy in the stability of transition metal nanoclusters of different motifs.

When a structure is reduced to a nanometer scale, the proportion of the edge atoms increases significantly, which can play a crucial role in determining both their geometric and electronic properties, as demonstrated by the recently established generalized Wulff construction principle [S. F. Li, et al., Phys. Rev. Lett., 2013, 111, 115501]. Consequently, it is of great interest to clarify quantitatively the role of the edge atoms that dominate the motifs of these nanostructures. In principle, establishing an effective method valid for determining the absolute value of the surface energy and particularly the edge energy for a given nanostructure is expected to resolve such a problem. However, hitherto, it is difficult to obtain the absolute edge energy of transition metal clusters, particularly when their sizes approach the nanometer regime. In this paper, taking Ru nanoclusters as a prototypical example, our first-principles calculations introduce the concept of relative edge energy (REE), reflecting the net edge atom effect over the surface (facet) atom effect, which is fairly powerful to quasi-quantitatively estimate the critical size at which the crossover occurs between different configurations of a given motif, such as from an icosahedron to an fcc nanocrystal. By contrast, the bulk effect should be re-considered to rationalize the power of the REE in predicting the relative stability of larger nanostructures between different motifs, such as fcc-like and hcp-like nanocrystals.

Substrate co-doping modulates electronic metal-support interactions and significantly enhances single-atom catalysis.

Transitional metal nanoparticles or atoms deposited on appropriate substrates can lead to highly economical, efficient, and selective catalysis. One of the greatest challenges is to control the electronic metal-support interactions (EMSI) between the supported metal atoms and the substrate so as to optimize their catalytic performance. Here, from first-principles calculations, we show that an otherwise inactive Pd single adatom on TiO2(110) can be tuned into a highly effective catalyst, e.g. for O2 adsorption and CO oxidation, by purposefully selected metal-nonmetal co-dopant pairs in the substrate. Such an effect is proved here to result unambiguously from a significantly enhanced EMSI. A nearly linear correlation is noted between the strength of the EMSI and the activation of the adsorbed O2 molecule, as well as the energy barrier for CO oxidation. Particularly, the enhanced EMSI shifts the frontier orbital of the deposited Pd atom upward and largely enhances the hybridization and charge transfer between the O2 molecule and the Pd atom. Upon co-doping, the activation barrier for CO oxidation on the Pd monomer is also reduced to a level comparable to that on the Pd dimer which was experimentally reported to be highly efficient for CO oxidation. The present findings provide new insights into the understanding of the EMSI in heterogeneous catalysis and can open new avenues to design and fabricate cost-effective single-atom-sized and/or nanometer-sized catalysts.

Inner ear implants for experimental electrical stimulation of auditory nerve arrays.

Electrode arrays chronically implanted in the inner ear are gaining increased use for experimental studies of the auditory nervous system, as well as for studies related to development of improved auditory prostheses. Commercially available electrode arrays are designed for human use and thus may be unsuitable for experimental studies, particularly in small animals. This paper describes a simple, inexpensive method for making custom electrode arrays in a variety of configurations, suitable for animals ranging from small rodents to non-human primates.

Chronic skull-anchored percutaneous implants in non-human primates.

Three groups of chronic, skull-anchored, percutaneous implants differing in materials, design and surgical procedures used for implantation, were tested in macaque monkeys in conjunction with studies of an inner ear stimulation device. Implants from the first two groups in which high-speed drilling methods and stainless steel materials were used, showed a high percentage of failures during the first 3 months after implantation of the percutaneous connector. Implants in the third group, in which measures were taken to preserve living bone tissue, all survived for greater than 7 months. Probable factors relating to implant survival are care of the bone during surgery, postsurgical mechanical trauma, materials and other details of the surgical procedure.

Batch-fabricated thin-film electrodes for stimulation of the central auditory system.

Silicon micromachining and thin-film technology have been employed to fabricate iridium stimulating arrays which can be used to excite discrete volumes of the central nervous system. Silicon multichannel probes with thicknesses ranging from 1 to 40 microns and arbitrary two-dimensional shapes can be fabricated using a high-yield, circuit-compatible process. Iridium stimulating sites are shown to have similar characteristics to iridium wire electrodes. Accelerated pulse testing with over 8 million 100 microA biphasic current pulses on 8000 microns 2 sites has demonstrated the long-term stability of iridium and activated iridium sites. In vivo tests have been performed in the central auditory pathways to demonstrate neural activation using the devices. These tests show a selective activation both as a function of site separation and site size.

Auditory brainstem prosthesis: biocompatibility of stimulation.

As part of a program to develop a central auditory system prosthesis, we have examined the reaction of tissue to different levels of stimulation from electrodes chronically implanted in the cochlear nucleus of the guinea pig. Tolerance and histologic reaction to 20 hours of periodic electrical stimulation of the cochlear nucleus were analyzed. Intraoperative and postoperative electrically evoked middle latency responses were monitored during stimulus trials. The threshold necessary to generate the middle latency responses was frequently below 50 microA. In the animals that received 50 and 100 microA of biphasic charge-balanced stimulation (corresponding to approximately 200 and 400 microC/cm2 phase), adverse tissue reaction was minimal, and glial proliferation along the electrode tract never exceeded 25 microns in width. Stimulation intensities of 150 and 200 microA (approximately 600 and 800 microC/cm2 phase) produced significant tissue response at the site of the electrode terminus, with necrosis, cell loss, and reactive cells present. Therefore neuronal damage was observed to occur at an intensity far greater than that required for eliciting an electrophysiologic response.

Surgical implantation and biocompatibility of central nervous system auditory prostheses.

As part of a program to determine the feasibility of a CNS auditory prosthesis, the tissue reaction to electrodes chronically implanted in the cochlear nucleus (CN) of the guinea pig was examined. Varied open operative approaches and microelectrode designs were utilized. Silicon substrate thin film and platinum-iridium wire electrodes, tethered and untethered, were placed successfully in different divisions of the CN. Implantation through a posterior suboccipital approach was most successful. Histologic examinations demonstrated a glial cell proliferation confined to the area of the electrode track that never exceeded 15 microns in width. No neuronal loss or significant effect on cell morphology was seen, and reactive cells were absent. Electrode migration was apparent in a minority of animal preparations. Although potential problems were identified, our findings lend support to the feasibility of implanting a neuroprosthesis in the CN and have helped to establish methods for future studies of chronic intranuclear stimulation.

Identification of the critical role of Tyr-194 in the catalytic activity of a novel N-acyl-homoserine lactonase from marine Bacillus cereus strain Y2.

Enzymatic disruption of quorum-sensing (QS) pathways in pathogenic organisms is a promising anti-infection therapeutic strategy. AHL-lactonase, a potent tool for biocontrol, can hydrolyze QS signal molecule N-acyl-homoserine lactones (AHLs) into inactive products, thereby blocking the QS systems. A marine bacterial isolate Y2, identified as a Bacillus cereus subsp., was found capable of inactivating AHLs. The aiiA gene encoding the AHL-degrading enzyme from bacterial strain Y2 was cloned and expressed in Escherichia coli. The 28-kDa recombinant Y2-AiiA protein was purified and showed strong AHL-degrading activity. Sequence comparisons of Y2-aiiA with known AHL-lactonases revealed high identities in the deduced amino-acid sequences. Functional determination of a potential catalytic residue Tyr-194 of AHL-lactonases was performed by site-directed mutagenesis. As judged by AHL-degrading bioassay, substitution of Tyr-194 with Ala resulted in a dramatic decrease of activity compared with wild-type (WT) recombinant Y2-AiiA, although the expression level of the mutated Y2-AiiA protein was equivalent to that of WT Y2-AiiA. These results suggested that the conserved residue Tyr-194 is critical for catalytic function of the novel AHL-lactonase.

[Effect of alpha-lipoic acid on the apoptosis of PC12 cells induced by 6-hydroxydopamine].

PC12 cell line, a clonal cell line derived from a pheochromocytoma of rat adrenal medulla, was used as a model of dopaminergic neuron in vitro to study the effect of alpha-lipoic acid on the 6-OHDA induced apoptosis. The results from MTT method show that 6-OHDA decreased the cell survival rate obviously. Through TUNEL (TdT-mediated dUTP-biotion nick end labeling) and Flow cytometer (FCM) detection, we found that 6-OHDA triggered cell apoptosis and induced necrosis. It was confirmed by the different percentage of cell survival rate and apoptosis concluded from FCM and MTT. alpha-lipoic acid was used as antioxidant to protect the cell from 6-OHDA's injury. The result indicateed that alpha-lipoic acid can partly prevent apoptosis induced by 6-OHDA but fail to prevent necrosis since it can decrease the apoptotic cell from 20.09% to 3.09%, just as increased cell survival rate from 56.8% to 72.6% but can not reach the normal level showed by MTT assay. Biochemical approach showed the cell's antioxidant ability especial for SOD activity and GSH content increased after the treatment of alpha-lipoic acid. The data suggest that alpha-lipoic acid may protect PC12 cells from apoptosis induced by 6-OHDA through the antioxidant path.