Conformational Changes of CFTR upon Phosphorylation and ATP Binding.

The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel evolved from an ATP-binding cassette transporter. CFTR channel gating is strictly coupled to phosphorylation and ATP hydrolysis. Previously, we reported essentially identical structures of zebrafish and human CFTR in the dephosphorylated, ATP-free form. Here, we present the structure of zebrafish CFTR in the phosphorylated, ATP-bound conformation, determined by cryoelectron microscopy to 3.4 Å resolution. Comparison of the two conformations shows major structural rearrangements leading to channel opening. The phosphorylated regulatory domain is disengaged from its inhibitory position; the nucleotide-binding domains (NBDs) form a "head-to-tail" dimer upon binding ATP; and the cytoplasmic pathway, found closed off in other ATP-binding cassette transporters, is cracked open, consistent with CFTR's unique channel function. Unexpectedly, the extracellular mouth of the ion pore remains closed, indicating that local movements of the transmembrane helices can control ion access to the pore even in the NBD-dimerized conformation.

Application effect of computer-aided design combined with three-dimensional printing technology in autologous tooth transplantation: a retrospective cohort study.

BACKGROUND: The activity of donor periodontal membrane is the key factor of autologous tooth healing. The application of digital aided design, 3D printing model and guide plate in autotransplantation of tooth (ATT) is expected to reduce the damage of periodontal membrane and preserve the activity of periodontal membrane, so as to improve the success rate of ATT. This study tried to prove the role of digital technology in improving the success rate of ATT, although there are differences in model accuracy in practice. METHODS: We included 41 tooth autotransplantation cases which assisted by 3D-printed donor models and surgical guides and divided them into two groups in accordance with whether the donor tooth could be placed successfully after the preparation of alveolar socket guided by the model tooth. Then, we compared and analyzed the preparation time of alveolar socket, extra-alveolar time, and number of positioning trials of the donor tooth between the two groups. We also included a comparison of the in vitro time of the donor tooth with that of 15 min. The incidence of complications was included in the prognostic evaluation. RESULTS: The mean preparation time of the alveolar socket, mean extra-alveolar time of donor tooth, and mean number of positioning trials with donor tooth of 41 cases were 12.73 ± 6.18 min, 5.56 ± 3.11 min, and 2.61 ± 1.00, respectively. The group wherein the donor tooth cannot be placed successfully (15.57 ± 6.14 min, 7.29 ± 2.57 min) spent more preparation time of alveolar socket and extra-alveolar time than the group wherein the donor tooth can be placed successfully (9.75 ± 4.73 min, 3.75 ± 2.57 min). The number of positioning trials with the donor tooth of the group wherein the donor tooth cannot be placed successfully (3.19 ± 0.75) was higher than that of the other group (2.00 ± 0.86). There was no significant difference in survival rates between the two groups. CONCLUSIONS: Compared with the traditional tooth autotransplantation, the introduction of computer-aided design combined with 3D printing of the model tooth and surgical guides evidently shortens the preparation time of the alveolar socket and the extra-alveolar time of the donor tooth and reduces the number of positioning trials with the donor tooth regardless of the shape deviation between the model and actual teeth.

Study of oral microorganisms contributing to non-carious cervical lesions via bacterial interaction and pH regulation.

There is a lack of evidence about the relationship between microorganisms and non-carious cervical lesions (NCCLs) due to limited technologies. A group of 78 patients was enrolled for microbial 16S rRNA sequencing of dental plaques on normal and defective cervical surfaces. Parallel data from 39 patients were analysed with paired t tests, and Fusobacteriales exhibited significantly less distribution on NCCLs than on normal surfaces. As a result, Fusobacterium nucleatum, the most common oral bacterial strain belonging to the order Fusobacteriales, was selected for further research. From a scanning electron microscopy (SEM) scan, the tooth surface with Fusobacterium nucleatum and Streptococcus mutans culture was more intact than that without Fusobacterium nucleatum. Furthermore, the calcium contents in groups with Fusobacterium nucleatum were significantly higher than that without it. In further mechanistic research, Fusobacterium nucleatum was demonstrated to adhere to and disturb other organisms as well as producing alkaline secretions to neutralize the deleterious acidic environment, protecting the tooth structure. In conclusion, microorganisms and NCCLs were confirmed directly related through adherent bacterial interactions and pH regulation. The research provides a new perspective and experimental evidence for the relation between microorganisms and NCCLs, which guides clinical treatment and preventive dentistry in the future.

Scanning Electron Microscopic Assessment of Stent Coating Integrity in Jailed Wire Technique for Bifurcation Treatment.

OBJECTIVES: To assess the impact of different guidewires on stent coating integrity in jailed wire technique (JWT) for bifurcation treatment. BACKGROUND: JWT is commonly adopted to protect side branch in provisional one-stent strategy for coronary bifurcation lesions. However, this technique may cause defects in stent coatings. The degree of coating damage caused by different types of jailed wires remains unknown. METHODS: A fluid model with a bifurcation was established to mimic the condition in vivo. One-stent strategy was performed with three types of guidewire (nonpolymer-jacketed wire, intermediate polymer-jacketed wire, and full polymer-jacketed wire) tested for JWT. Scanning electron microscopy (SEM) was used to evaluate stent coating integrity and wire structure. The degrees of coating defects were recorded as no, slight, moderate, and severe defects. RESULTS: A total of 27 samples were tested. Analyses of SEM images showed a significant difference in the degree of coating damage among the three types of wire after the procedure of JWT (P < 0.001). Nonpolymer-jacketed wire could inevitably cause a severe defect in stent coatings, while full polymer-jacketed wire caused the least coating damages. Besides, there were varying degrees of coil deformation in nonpolymer-jacketed wires, while no surface damage or jacket shearing was observed in full polymer-jacketed wires. CONCLUSIONS: Although nonpolymer-jacketed wire has long been recommended for JWT, our bench-side study suggests that full polymer-jacketed wire may be a better choice. Further clinical studies are needed to confirm our findings.

Preparation, optimisation, and properties of O-carboxymethyl chitosan-g-cholesterol succinic acid monoester polymer nanomicelles.

Polymer nanomicelles have the advantages of small particle size, improved drug solubility, retention effect and enhanced permeability, so they can be used in the treatment of tumour diseases. The aim of this study was to prepare and optimise a nanomicelle which can improve the solubility of insoluble drugs. Firstly, the carboxyl group of cholesterol succinic acid monoester was grafted with the side chain amino group of O-carboxymethyl chitosan-g-cholesterol succinic acid monoester (CCMC), and its structure was characterized by fourier transform infrared spectroscopy (FTIR) and proton nuclear magnetic resonance (1H-NMR). Particle size has an important impact on tissue distribution, cell uptake, permeability and inhibition of tumour tissue. In this study, particle size and polydispersity index (PDI) were selected as indexes to optimise the preparation process of CCMC nanomicelles through single factor experiment, Plackett-Burman experiment, the steepest climbing experiment and response surface design experiment. The optimised CCMC nanomicelles showed an average particle size of 173.9 ± 2.3 nm and a PDI of 0.170 ± 0.053. The Cell Counting Kit-8 assay showed no significant effect on cell viability in the range of 0-1000 µg ml-1concentration. Coumarin-6 (C6) was used as a fluorescent probe to investigate the drug-carrying ability of CCMC nanomicelles. C6-CCMC showed 86.35 ± 0.56% encapsulation efficiency with a drug loading of 9.18 ± 0.32%. Both CCMC and C6-CCMC demonstrated excellent stability in different media. Moreover, under the same conditions, the absorption effect of C6 in C6-CCMC nanomicelles was significantly higher than that of free C6 while also exhibiting good sustained-release properties. Therefore, this study demonstrates CCMC nanomicelles as a promising new drug carrier that can significantly improve insoluble drug absorption.

Immediate and long-term outcomes of drug-eluting stent implantation for unprotected left main coronary artery disease: comparison with bare-metal stent implantation.

BACKGROUND: The efficacy and safety of drug-eluting stent (DES) implantation for unprotected left main coronary artery (LMCA) disease remain to be established in different clinical settings. METHODS: Elective DES implantation for unprotected LMCA stenosis was performed in 220 patients at the Fu Wai Hospital, China, from April 2003 to February 2006. Data derived from the latter group were compared with those derived from 224 patients treated with bare-metal stents (BMSs) before March 2003 in a Chinese registry of unprotected LMCA stenting. RESULTS: Compared with the historical BMS control group, the DES group had more multivessel disease and underwent more bifurcation stenting. The inhospital major adverse cardiac events were significantly higher in the DES than in the BMS recipients (4.1% vs 0.9%, P = .030) because of more complex lesions and procedures in the DES group. During the 15-month mean follow-up period, cumulative cardiac death (0.5% vs 4.9%, P = .004), target-vessel revascularization (5.9% vs 11.6%, P = .034), and major adverse cardiac event (9.5% vs 16.5%, P = .029) rates were significantly lower in the DES than in the BMS group. There was no significant difference in clinical efficacy between sirolimus- and paclitaxel-eluting stents. Angiographic follow-up was performed in 46.4% of DES and 45.7% of BMS recipients, respectively; and the binary restenosis rate was significantly lower in the DES versus the BMS control group (16.7% vs 31.4%, P = .014). CONCLUSIONS: Based on this comparison with a historical control, DES implantation for unprotected LMCA appears safe in selected patients and might be more effective in preventing major adverse cardiac events compared with BMS implantation over a mean follow-up period of 15 months.

A comparison of clinical and angiographic outcomes after Excel bioabsorbable polymer versus Firebird durable polymer rapamycin-eluting stent for the treatment of coronary artery disease in a "real world" setting: six-month follow-up results.

BACKGROUND: Several clinical trials have shown that rapamycin-eluting stents significantly reduce the risk of restenosis after percutaneous coronary intervention (PCI). The Firebird stent and the Excel stent (coated with bioabsorbable polymer) are two different types of rapamycin-eluting stents made in China, both have been recently approved for clinical use in China by State Food and Drug Administration. However, it is unclear whether there are differences in safety and efficacy between the two types of stents in daily practice. METHODS: In the month of June 2006, a total of 190 consecutive patients were treated exclusively with Firebird stents (n = 93, Firebird group) or Excel stents (n = 97, Excel group) in our center and were included in this study. The frequency of major adverse cardiac events (MACE, a composite of death, myocardial infarction or target lesion revascularization), binary restenosis, and late lumen loss and stent thrombosis during a six-month follow-up period were compared between the two groups. RESULTS: Patient and lesion characteristics were comparable between the groups. Major adverse cardiac event rates were low in hospital and at 6 months (2.1% in the Excel group and 0% in the Firebird group, P > 0.05). The 6-month angiographic in-stent restenosis rate was 0% in both groups, with an associated late loss of (0.15 +/- 0.21) mm versus (0.14 +/- 0.20) mm (P = 0.858) and the in-segment restenosis rate was also 0% for the Excel group and the Firebird group. There was no definite stent thrombosis identified in either group during the six-month follow-up period and only one patient in the Excel group had probable stent thrombosis in hospital. CONCLUSIONS: Results from this mid-term, single-center study showed that both of the Firebird and the Excel rapamycin eluting stent had similar effects on reducing the incidence of MACE and the risk of restenosis (both in-stent and in-segment binary restenosis) after PCI in daily practice.

Optical coherence tomography assessment of a PLGA-polymer with electro-grafting base layer versus a PLA-polymer sirolimus-eluting stent at three-month follow-up: the BuMA-OCT randomised trial.

AIMS: To compare stent strut coverage using optical coherence tomography (OCT) at three-month follow-up between a PLGA-polymer with electro-grafting base layer sirolimus-eluting stent (SES) (BuMA) and a PLA-polymer SES (EXCEL). METHODS AND RESULTS: This prospective, single-centre, non-inferiority randomised BuMA-OCT trial enrolled patients with de novo coronary artery lesions, treated with either the BuMA or the EXCEL stent. The study primary endpoint was OCT-evaluated stent strut coverage at three months. Secondary endpoints were neointimal thickness of stent struts, and incomplete stent apposition evaluated with OCT. A total of 80 patients were randomly assigned to receive the BuMA (n=40) or the EXCEL (n=40) stent. In OCT follow-up (achieved in 86.3% of cases: BuMA, n=33; EXCEL, n=36), the percentage of stent strut coverage was significantly higher in the BuMA vs. the EXCEL group (strut level: 94.2% vs. 90.0%, p<0.01; p(non-inferiority)<0.0001; p(superiority) <0.0001), while the proportion of malapposed struts (strut level: 1.28% vs. 1.80%, p=0.51) and the mean neointimal thickness (strut level: 0.07±0.03 mm vs. 0.06±0.02 mm, p=0.31) were similar. Rates of myocardial infarction (periprocedural non-Q-wave, 7.5% vs. 7.5%, p=1.00) and target lesion failure (7.5% vs. 7.5%, p=1.00) were similar between groups, with no cardiac death or stent thrombosis. CONCLUSIONS: In the BuMA-OCT randomised trial, the novel BuMA PLGA-polymer with electro-grafting base layer SES was superior to the EXCEL PLA-polymer SES in the primary endpoint of stent strut coverage at three-month follow-up.

First report of a novel abluminal groove filled biodegradable polymer rapamycin-eluting stent in de novo coronary artery disease: results of the first in man FIREHAWK trial.

BACKGROUND: Durable polymers used for first-generation drug-eluting stents (DES) potentially contribute to persistent inflammation and late DES thrombosis. We report the first in human experience with the rapamycin-eluting biodegradable polymer coated cobalt-chromium FIREHAWK stent with abluminal groove. METHODS: A total of 21 patients with stable or unstable angina, or prior myocardial infarction, with single de novo native coronary stenoses < 30 mm in length in vessel sizes ranging from 2.25 to 4.0 mm were enrolled. The primary endpoint was major adverse cardiac events (MACE) at 30 days defined as the composite of cardiac death, myocardial infarction (Q and non-Q), or ischemia-driven target lesion revascularization. Secondary endpoints include device, lesion, and clinical success rates, 4-month in-stent late lumen loss by quantitative coronary angiography (QCA), proportion of uncovered or malapposed stent struts by optical coherence tomograpphy (OCT) at 4 months, and MACE at 4, 12, 24 and 36-month follow-up. RESULTS: Device success was 95.7%, lesion and clinical success was 100.0%. There were no MACE events at 30 days. One patient died of non-cardiac hemorrhagic stroke 5 days after index procedure. At 4 months, in-stent late loss was (0.13 ± 0.18) mm, and complete strut coverage was 96.2% by OCT with 0.1% strut malapposition. At 4-month follow-up there was no additional MACE events, and a single target vessel (non-target lesion) revascularization. CONCLUSIONS: The FIREHAWK abluminal groove biodegradable polymer rapamycin-eluting stent demonstrated feasibility, safety and efficacy in this first in human experience. OCT findings indicated excellent stent strut coverage 4 months after implantation. Larger studies are required to confirm whether the early FIREHAWK stent results translate into longer term restenosis and thrombosis benefits.