[Effect of ABO blood groups on long-term outcome of stable coronary artery disease after percutaneous coronary intervention]

Objective: To evaluate the effect of ABO blood groups on long-term outcome of stable coronary artery disease (CAD) after percutaneous coronary intervention (PCI). Methods: A total of 4 272 patients with stable coronary artery disease and received PCI were consecutively enrolled from January to December 2013 and followed up for 2 years. Patients were divided into O group and non-O group according to their ABO groups. Multivariable COX regression was used to evaluated the relationship between ABO blood groups and prognosis of CAD. The endpoints included all-cause death, cardiac death, myocardial infarction(MI), revascularization, and stroke. Results: There were 1 302 patients in O group and 2 970 patients in non-O group. ABO blood group was not associated with age, sex and blood pressure (P>0.05). The comorbidity rate of hypertension, diabetes mellitus, smoking, family history, previous MI, previous cerebrovascular disease, previous PCI and left ventricular ejection fraction were similar between the two groups (P>0.05). Total cholesterol, low density lipid cholesterol level were significantly higher in non-O group compared with O group [(4.2±1.1)mmol/L vs (4.1±1.1)mmol/L, P=0.027; (2.5±0.9)mmol/L vs (2.4±0.9) mmol/L, P=0.025], while high density lipid cholesterol level was significantly lower[(1.04±0.26) mmol/L vs (1.06±0.28) mmol/L, P=0.035]. As to angiographic results, non-O blood group was not related to the severity of coronary atherosclerosis assessed by SYNTAX score(P=0.277). More cardiac death occurred in non-O group compared with that in O group [21 (0.7%) vs 2(0.1%)] during 2-year follow-up. After adjusted for confounding factors, multivariable COX regression revealed that non-O blood type was not associated with increased cardiac death [HR (95%CI)=7.30(0.97-55.09), P=0.054]. Conclusion: Non-O blood group is associated with 2-year cardiac death in patients with stable coronary artery disease who received PCI, but it is not an independent risk factor for cardiac death.

[Diagnostic value of HBP, PCT combined with APACHE Ⅱ score respectively in ventilator-associated pneumonia]

Objective: To evaluate the diagnostic value of the heparin-binding protein (HBP), procalcitonin (PCT) and acute physiology and chronic health evaluation Ⅱ (APACHE Ⅱ) score in ventilator-associated pneμmonia (VAP). Methods: A total of 160 patients who required tracheotomy or intubation and assisted breathing with invasive mechanical ventilator from the First Affiliated Hospital of Zhengzhou University from January 2015 to January 2017 was included in this prospective study,and divided into VAP group and no-VAP group based on if VAP happened or not; the VAP group was further divided into deterioration group and improvement group based on the curative effect after anti-infective treatment for 1 week. A total of 40 community acquired pneumonia (CAP) patients and 30 healthy volunteers were also included as control groups. The levels of HBP and PCT in blood of the subjects were tested with enzyme-linked immuno sorbent assay (ELISA) and chemiluminescence immunoassay (ECLIA) respectively, APACHE Ⅱ score was utilized to assess the severity of illness. The difference of HBP, PCT levels and APACHE Ⅱ score among the groups were analyzed. Receiver operating characteristic(ROC) curve was utilized to analyze the diagnostic value of HBP, PCT, APACHE Ⅱ score in VAP. Results: A total of 230 subjects participated in this study, including 68 VAP patients, 92 non-VAP patients, 40 CAP patients and 30 healthy volunteers. Before administration of mechanical ventilation, there were no statistically significant differences in HBP, PCT and APACHE Ⅱ score between VAP group and non-VAP group (all P>0.05). The levels of HBP,PCT and APACHE Ⅱ score were (41.4±21.3) μg/L,(0.355±0.254) μg/L,(13.4±2.5) respectively when the VAP was diagnosed,which were higher than those within the first 12 h of mechanical ventilation (7.3±2.7) μg/L, (0.080±0.038) μg/L, (8.4±2.0), all P<0.001). The HBP, PCT and APACHE Ⅱ score had no significant difference between within the first 12 h of mechanical ventilation and after mechanical ventilation in non-VAP group (all P>0.05). The levels of HBP was positively correlated with PCT and APACHE Ⅱ score (r=0.82, 0.68, all P<0.001). In deterioration group,the HBP,PCT and APACHE Ⅱ score after 1 week of anti-infective treatment were higher than those when the VAP was diagnosed (all P<0.001). No matter it is when the VAP was diagnosed or after anti-infective treatment for 1 week,the levels of HBP, PCT and APACHE Ⅱ score in deterioration group were higher than those in the improvement group (all P<0.001). The area under curve (AUC) of HBP+APACHE Ⅱ score, PCT+APACHE Ⅱ score for VAP diagnosis was 0.98, 0.95 respectively. The sensitivity of HBP+APACHE Ⅱ score in the diagnosis of VAP was lower than PCT+APACHE Ⅱ score (94.1% vs 95.6%),and the specificity was higher (92.4% vs 82.6%). Conclusion: The diagnostic value of HBP+APACHE Ⅱ score for early VAP is superior to PCT+APACHE Ⅱ score.

Photosynthetic regulation under fluctuating light in young and mature leaves of the CAM plant Bryophyllum pinnatum

Photosystem I (PSI) is the potential target of photodamage under fluctuating light in angiosperms. However, the response of PSI to fluctuating light in young leaves has not yet been clarified. Furthermore, the photosynthetic regulation under fluctuating light in crassulacean acid metabolism (CAM) plants is little known. In this study, we measured PSI redox state and the electrochromic shift signal in the mature and young leaves of a CAM species Bryophyllum pinnatum. The mature leaves showed stronger capacity for photo-reduction of O₂ mediated by the alternative electron flow (probably the water-water cycle) when compared with the young leaves. After an increase in light intensity, both the mature and young leaves showed insufficient proton gradient (ΔpH) across the thylakoid membranes within the first seconds. Meanwhile, PSI was highly oxidized in the mature leaves but was in a more reduced state in the young leaves. Furthermore, young leaves were more susceptible to PSI photoinhibition under fluctuating light. Therefore, in the mature leaves, the alternative electron flow significantly optimized the PSI redox state under fluctuating light at relatively low ΔpH. By comparison, in the young leaves, PSI redox state was largely determined by the buildup of ΔpH. Therefore, the major photoprotective mechanism responsible for safeguarding PSI under fluctuating light can be influenced by leaf developmental stages.

[Prognostic value of TIMI and GRACE risk scores for in-hospital mortality in Chinese patients with non-ST-segment elevation myocardial infarction]

Objective: To evaluate the prognostic value of the thrombolysis in myocardial infarction (TIMI) and global registry of acute coronary events (GRACE) risk scores for in-hospital mortality in Chinese non-ST-segment elevation myocardial infarction (NSTEMI) patients. Methods: Data of present study derived from the prospective, multi-center registry trial of Chinese AMI (CAMI). Among 31 provinces, municipalities or autonomous districts in China, at least one tertiary and secondary hospital was selected. From January 2013 to September 2014, 5 896 consecutive non-ST-segment elevation myocardial infarction patients who were admitted to 107 hospitals within 7 days of symptom onset were enrolled. For each patient, TIMI and GRACE risk scores were calculated using specific variables collected at admission. Their prognostic value was evaluated by the endpoint of in-hospital mortality. Results: Among 5 896 NSTEMI patients (age was (65.4±12.1) years old), 68.2% (n=4 020) were males. The in-hospital mortality was 6.0% (n=353) and the median length of hospital stay was 10.0 (7.0, 13.0) days. The incidence of pre-hospital cardiac arrest was 3.6% (n=213) among 5 896 NSTEMI patients. Six hundreds and forty five patients (10.9%) received primary percutaneous coronary intervention, and 6 patients underwent emergent coronary artery bypass grafting surgery (0.1%), and the median time of reperfusion was 529.5 (256.0, 1 065.0) minutes. The prescription percentage of statins, β-blocker, angiotensin converting enzyme inhibitors or angiotensin Ⅱ receptor blockers, and aldosterone antagonists were 94.8% (n=5 587), 71.7% (n=4 228), 65.5% (n=3 864) and 26.0% (n=1 533) respectively. The area under the curve of GRACE risk score for in-hospital mortality (0.7930 (95%CI 0.767-0.818)) was better than that of TIMI risk score (0.5588 (95%CI 0.532-0.586), P<0.001). Conclusion: GRACE risk score demonstrates better predictive accuracy than TIMI risk score for in-hospital mortality in NSTEMI patients in this patient cohort.

The role of water-water cycle in regulating the redox state of photosystem I under fluctuating light

The regulation of photosystem I (PSI) redox state under fluctuating light was investigated for four species using P700 measurement and electrochromic shift analysis. Species included the angiosperms Camellia japonica, Bletilla striata and Arabidopsis thaliana and the fern Cyrtomium fortunei. For the first seconds after transition from low to high light, all species showed relatively low levels of the proton gradient (ΔpH) across the thylakoid membranes. At this moment, PSI was highly oxidized in C. japonica and C. fortunei but was over-reduced in B. striata and A. thaliana. In B. striata and A. thaliana, the redox state of PSI was largely dependent on ΔpH. In contrast, the rapid oxidation of P700 in C. japonica was relatively independent of ΔpH, but was mainly dependent on the outflow of electrons to O₂ via the water-water cycle. In the fern C. fortunei, PSI redox state was rapidly regulated by the fast photo-reduction of O₂ rather than the ΔpH. These results indicate that mechanisms regulating PSI redox state under fluctuating light differ greatly between species. We propose that the water-water cycle is an important mechanism regulating the PSI redox state in angiosperms.

[Safety and efficacy of second generation drug eluting stents in diabetic and non-diabetic patients]

Objective: To investigate the long-term prognosis of Second generation drug-eluting stents(G2-DES) in diabetic mellitus(DM) and non-DM patients. Methods: Patients with coronary heart disease(CHD) in Fuwai Hospital from January 2013 to December 2013 who had exclusively G2-DES implantation, were consecutively included the follow-up period was 2 years. Results: A total of 6 094 patients with CHD were implanted with G2-DES, of which 1 862 patients with DM, and 4 232 patients without DM.The proportion of DM patients receiving G2-DES implantation with the following characteristics: advanced age, female, hypertension, hyperlipidemia, history of previous stroke, history of peripheral artery disease, previous history of PCI, and with triple vessel, high preoperative Syntax score, high number of target lesions, B2 or C type lesions, severe calcification lesions, and chronic occlusive disease were significantly higher than those of non-DM patients(P<0.05). The incidence of major adverse cardiac and cerebral vascular events(MACCE), target vascular revascularization(TVR) and target lesion revascularization(TLR) were higher in DM patients than in non-DM patients during 2 year's follow-up(P<0.05). The univariate COX regression analysis showed that diabetes was risk factor for MACCE in patients with CHD implanting G2-DES(HR=1.241, 95%CI: 1.053-1.463, P=0.010). However, multivariable COX analysis showed that DM was not an independent risk factor for MACCE in CHD patients with G2-DES(HR=1.125, 95%CI: 0.952-1.330, P=0.167). While age, female, preoperative Syntex score, triple vessel, B2 or C lesion were independent risk factors for poor clinical prognosis in CHD patients with G2-DES. Conclusions: (1) CHD patients with DM often accompany more clinical risk factors and complicated coronary lesions; (2) the incidence of MACCE, TVR and TLR in DM patients is significantly higher than non-DM patients with G2-DES during the 2 year's follow-up; (3) after multivariate adjustment, DM is not an independent risk factor for poor clinical prognosis in CHD patients with G2-DES, while traditional risk factors and complex coronary lesions are independent risk factors for poor clinical prognosis.

[New insight of craniofacial and oral findings of the RASopathies]

The RASopathies are a group of syndromes that have in common germline mutations in genes that encode components of the RAS/mitogen-activated protein kinase (MAPK) pathway and have been a focus of study to understand the role of this pathway in development and disease. These syndromes include Noonan syndrome (NS), NS with multiple lentigines (NSML), neu-rofibromatosis type 1 (NF1), Costello syndrome (CS), cardio-facio-cutaneous (CFC) syndrome, neurofibromatosis type 1-like syndrome (NFLS) and capillary malformation-arteriovenous malformation syndrome (CM-AVM). These disorders affect multiple systems, including the craniofacial complex. Although the crani-ofacial features have been well described and can aid in clinical diagnosis, the dental phenotypes have not been analysed in detail for each of the RASopathies. In this review, we summarize the clinical features of the RASopathies, highlighting the reported craniofacial and dental findings.

[Predictive value of neutrophil to lymphocyte ratio on long-term outcomes of acute myocardial infarction patients with multivessel disease]

Objective: Patients with acute coronary syndrome due to multivessel disease (MVD) were at the highest risk of adverse cardiovascular events. Neutrophil to lymphocyte ratio (NLR) was proposed as a marker of cardiovascular risk. Present study evaluated the independent predictive value of NLR for acute myocardial infarction (AMI) patients with MVD. Methods: AMI patients with MVD (n=1 433) underwent percutaneous coronary intervention (PCI) between January 2013 and December 2013 were followed up for 2 years. Patients were divided into 2 sub-groups based on an optimal cut off value of NLR to predict 2-year all-cause mortality. The primary endpoint was all-cause death. The secondary endpoint was long-term major adverse cardiovascular and cerebrovascular events (MACCE). Results: By receiver operating characteristics curve analysis, the optimal cut-off value of admission NLR to predict 2-year all-cause mortality was 3.39 (area under the curve 0.765, sensitivity 71%, specificity 73%). The high NLR group(n=396) had higher prevalence of prior myocardial infarction, prior PCI and intra-aortic balloon pump use (IABP)(P<0.01). Compared to the low NLR group (n=1 037), patients in the high NLR group were older, had higher level of neutrophil count and high-sensitivity C-reactive protein (hs-CRP) (P<0.001), but lower level of lymphocyte count, estimated glomerular filtration rate (eGFR) and ejection fraction (P<0.001). During the follow-up period, rate of long-term all-cause death was significantly higher in the high NLR group than in the low NLR group (5.1% (20/396) vs. 0.8% (8/1 037), P<0.001). Cardiac death (4.0% (16/396) vs. 0.7% (7/1 037), P<0.001) and MACCE (21.7% (86/396) vs. 12.6% (131/1 037), P<0.001) were also significantly higher in the high NLR group than in the low NLR group. Multivariate Cox analysis showed that NLR ≥ 3.39 was determined as an independent predictor of 2-year all-cause mortality (HR=3.23, 95%CI 1.38-7.54, P=0.007) and MACCE (HR=1.58, 95%CI 1.19-2.10, P=0.002) in this patient cohort after adjusting for other risk factors. Correlation analysis showed that the NLR was positively correlated with hs-CRP levels (r=0.241, P<0.001). Conclusion: Our study demonstrates that admission NLR ≥ 3.39 is an independent predictor of long term all cause death and MACCE in AMI patients with MVD post PCI.

[Impact of coronary artery lesion calcification on the long-term outcome of patients with coronary heart disease after percutaneous coronary intervention]

Objective: To investigate the impact of coronary lesion calcification on the long-term outcome of patients with coronary heart disease after percutaneous coronary intervention. Methods: In this prospective observational study, a total of 10 119 consecutive patients with coronary heart disease undergoing percutaneous coronary intervention from January 1 to December 31, 2 103 in our hospital were enrolled. The patients were divided into non/mild calcification group (8 268 cases) and moderate/severe calcification group (1 851 cases) according to the angiographic results. The primary endpoint was one-year major adverse cardiovascular events (MACE), including all-cause death, myocardial infarction, and target vessel revascularization. Results: The patients were (58.3±10.3) years old, and there were 2 355 females (23.3%). Compared with non/mild calcification group, patients in the moderate/severe calcification group were older ((60.0±10.6) years vs. (57.9±10.2) years, P<0.01), and had higher proportion of female (25.4% (470/1 851) vs. 22.8% (1 885/8 268), P=0.02), debates (33.9% (628/1 851) vs. 29.0% (2 399/8 268), P<0.01), hypertension (68.0% (1 259/1 851) vs. 63.7% (5 264/8 268), P<0.01), coronary artery bypass grafting (4.6% (85/1 851) vs. 3.2% (268/8 268), P<0.01), stroke (12.6% (233/1 851) vs. 10.4% (861/8 268), P=0.01), and renal dysfunction (6.2% (115/1 851) vs. 3.7% (303/8 268), P<0.01). Compared with non/mild calcification group, patients in themoderate/severe calcification group experienced longer procedure time (37 (24, 61) min vs. 27 (17,40) min, P<0.01) and stent length was longer (32 (23,48) mm vs. 27 (18,38) mm, P<0.01), and percent of rotational atherectomy was higher (2.56%(57/2 229) vs. 0.03% (3/11 930), P<0.01). One-year follow-up results showed that MACE (7.5% (139/1 846) vs. 4.9% (402/8 243), P<0.01), all-cause death (1.0% (19/1 846) vs. 0.6% (49/8 243), P=0.04), myocardial infarction (2.2% (41/1 846) vs. 1.4% (114/8 243), P=0.01), and target vessel revascularization (5.0% (92/1 846) vs. 3.2% (266/8 243), P<0.01) were all significantly higher in moderate/severe calcification group than in non/mild group. Multivariate Cox regression analysis showed that moderate/severe calcification was an independent predictor of MACE at one-year after the procedure (HR=1.41, 95%CI 1.16-1.72, P<0.01). Conclusion: Moderate/severe calcification in coronary lesion is an independent predictor of long-term poor prognosis in coronary heart disease patients undergoing percutaneous coronary intervention.

[Relationship between thrombolysis in myocardial infarction risk index and the severity of coronary artery lesions and long-term outcome in acute myocardial infarction patients undergoing percutaneous coronary intervention]

Objective: To investigate the relationship between thrombolysis in myocardial infarction risk index(TRI) and the severity of coronary artery lesions and long-term outcome in acute myocardial infarction(AMI) patients undergoing percutaneous coronary intervention(PCI). Methods: A total of 1 663 consecutive AMI patients undergoing PCI between January and December 2013 in Fuwai hospital were prospectively included in this study. The severity of coronary artery lesions was evaluated using the SYNTAX score. Receiver operating characteristic(ROC) curve was used to analyze the optimal cut-off value of TRI on predicting all-cause mortality at 2 years after PCI.The patients were divided into 2 groups based on the optimal cut-off value of TRI:high TRI group (TRI ≥ 23.05, 465 cases) and low TRI group(TRI<23.05, 1 198 cases). Multivariate logistic regression analyses were used for determining the relationship between TRI and SYNTAX scores≥33. A multivariate Cox regression analyses was used to identify the influence factors of long-term outcome after PCI. Results: SYNTAX score was higher in high TRI group than in low TRI group (13.00(7.00, 20.50) vs.10.25(7.00, 17.00), P<0.001). TRI was independently associated with SYNTAX score ≥ 33 (OR=1.09,95% CI 1.03-1.16, P=0.004). After the 2 years follow-up, rates of all-cause death (4.1% (19/465) vs. 0.3% (4/1 198) , P<0.001), cardiac death (2.6% (12/465) vs. 0.2% (2/1 198) , P< 0.001) and stent thrombosis (1.7% (8/465) vs. 0.5% (6/1 198) , P=0.015) were all significantly higher in high TRI group than in low TRI group. Multivariate Cox regression analyses showed that TRI≥ 23.05 was an independent risk factor of all-cause death (HR=5.22, 95%CI 1.63-16.72, P=0.005), cardiac death (HR=8.48, 95%CI 1.75-41.07, P=0.008) and stent thrombosis(HR=3.87, 95%CI 1.32-11.41, P=0.014) at 2 years after PCI in AMI patients, but which was not the independent risk factor of major adverse cardiovascular and cerebrovascular events (HR=0.96, 95%CI 0.69-1.36, P=0.834) .The area under ROC curve of TRI ≥ 23.05 on predicting 2 years all-cause mortality in AMI patients undergoing PCI was 0.803(95%CI 0.711-0.894, P<0.001). Conclusions: TRI is independently associated with SYNTAX score ≥ 33. TRI is also an independent risk factor of 2 years all-cause death, cardiac death and stent thrombosis in AMI patients undergoing PCI.

Chloroplastic ATP Synthase Alleviates Photoinhibition of Photosystem I in Tobacco Illuminated at Chilling Temperature

Chloroplastic ATP synthase plays a significant role in the regulation of proton motive force (pmf) and proton gradient (ΔpH) across the thylakoid membranes. However, the regulation of chloroplastic ATP synthase at chilling temperature and its role in photoprotection are little known. In our present study, we examined the chlorophyll fluorescence, P700 signal, and electrochromic shift signal at 25°C, and 6°C in tobacco (Nicotiana tabacum L. cv. Samsun). Although photosynthetic electron flow through both PSI and PSII were severely inhibited at 6°C, non-photochemical quenching and P700 oxidation ratio were largely increased. During the photosynthetic induction under high light, the formation of pmf at 6°C was similar to that at 25°C. However, the ΔpH was significantly higher at 6°C, owing to the decreased activity of chloroplastic ATP synthase (g H +). During illumination at 6°C and high light, a high ΔpH made PSI to be highly oxidized, preventing PSI from photoinhibition. These results indicate that the down-regulation of g H + is critical to the buildup of ΔpH at low temperature, adjusting the redox state of PSI, and thus preventing photodamage to PSI. Our findings highlight the importance of chloroplastic ATP synthase in photoprotection at chilling temperature.

Genome Editing in Model Strain Myxococcus xanthus DK1622 by a Site-Specific Cre/loxP Recombination System

Myxococcus xanthus DK1622 is a rich source of novel secondary metabolites, and it is often used as an expression host of exogenous biosynthetic gene clusters. However, the frequency of obtaining large genome-deletion variants by using traditional strategies is low, and progenies generated by homologous recombination contain irregular deletions. The present study aims to develop an efficient genome-engineering system for this bacterium based on the Cre/loxP system. We first verified the functionality of the native cre system that was integrated into the chromosome with an inducible promoter P_cuoA. Then we assayed the deletion frequency of 8-bp-spacer-sequence mutants in loxP by Cre recombinase which was expressed by suicide vector pBJ113 or self-replicative vector pZJY41. It was found that higher guanine content in a spacer sequence had higher deletion frequency, and the self-replicative vector was more suitable for the Cre/loxP system, probably due to the leaky expression of inducible promoter P_cuoA. We also inspected the effects of different antibiotics and the native or synthetic cre gene. Polymerase chain reaction (PCR) and sequencing of new genome joints confirmed that the Cre/loxP system was able to delete a 466 kb fragment in M. xanthus. This Cre/loxP-mediated recombination could serve as an alternative genetic manipulation method.

[Surface microstructure and cyclic fatigue resistance of electro discharged machining nickel-titanium endodontic instrument]

OBJECTIVE

To compare the surface microstructures and cyclic fatigue resistance of HyFlex EDM with HyFlex CM and HyFlex NT.

METHODS

Twelve 25 mm-long 25#/- HyFlex EDM and twelve 25 mm-long 25#/0.06 taper HyFlex CM or HyFlex NT were selected. The surface microstructure of the 2 instruments which were randomly selected from each group was observed by using scanning electron microscope (SEM). The remaining 10 instruments from each group were submitted to the cyclic fatigue test by using a simulated stainless steel root canal with 60° angle of curvature and curvature radius of 3.5 mm. The time till fracture was recorded, the number of cyclic fatigue (NCF) was calculated, the length of fracture fragment was evaluated, and the topographic features were analyzed by using SEM. The data were analyzed by using one-way analysis via SPSS 23.0 software. The statistical significance level was set at 0.05.

RESULTS

SEM observation of the surface and microstructural characterization revealed peculiar melting appearance and evenly distributed micropores on the surface of HyFlex EDM while observations of the surface of both HyFlex CM and HyFlex NT demonstrated machining grooves and irregularities. The NCF of HyFlex EDM was 838±223, which was significantly higher than not only that of HyFlex CM (582±99), but also that of HyFlex NT (81±20) (P<0.05), and the difference between the latter two groups was significant, as well (P<0.05). The length of fractured fragments of HyFlex EDM was (7.27±0.28) mm, which was significantly longer than the HyFlex CM and HyFlex NT, with values of (6.72±0.26) mm and (6.62±0.37) mm, respectively (P<0.05). Topographic features demonstrated typical cyclic fatigue for all the three groups while the region of crack origins was more for HyFlex EDM and HyFlex CM than that of HyFlex NT. As far as the dimple area was concerned, that of HyFlex EDM was deeper and larger than that of HyFlex CM and HyFlex NT.

CONCLUSION

Within the limitations of this study, electro-discharge machining leads to peculiar melting appearance with micropores instead of machining grooves and irregularities on the surface of HyFlex EDM, which may be the reason why HyFlex EDM exhibits significantly better cyclicfatigue resistance than HyFlex CM and HyFlex NT.

[Effect of autoclave on surface microstructure and cyclic fatigue resistance of R-phase rotary instruments]

OBJECTIVE

To compare the effects of autoclave on surface microstructure and cyclic fatigue resistance of K3XF and K3.

METHODS

Forty-eight size 25, 0.06 taper 25 mm-long K3XF or K3 were randomly divided into 4 groups (n=12). The instruments from group 1 were not autoclaved, and the groups 2 to 4 underwent autoclave for 10 cycles, 20 cycles, and 30 cycles, respectively. The surface microstructure of two instruments randomly selected from each group was observed using scanning electron microscope (SEM). The remaining 10 instruments were submitted to the cyclic fatigue test by using a simulated metal root canal with curvature of 60° and radius 3.5 mm. The time till fracture was recorded, the number of cyclic fatigue (NCF) calculated, the fragment length evaluated, and the topographic features were analyzed using SEM. The data were analyzed using the two-way ANOVA analysis by SAS 9.3 software at a significance level of P<0.05.

RESULTS

SEM observation identified rough features on the surface of K3XF with micropores existing evenly. K3 was characterized by machining grooves, which located specifically in the flute, leaving a smooth cutting edge. After autoclave, SEM observation indicated that the micropores in the surface of K3XF became larger and more, whereas the machining grooves in the surface of K3 were squeezed, out of shape and flaking. As far as the NCF was concerned, new K3XF was 210±59, and no significant difference was found after 10, 20, and 30 cycles of autoclave for K3XF, values being 178±37, 208±48, and 227±43, respectively (P>0.05). For K3, the new one was 145±38, and no significant difference in NCF was demonstrated after 10 and 20 cycles of autoclave, with the values of 128±43 and 124±46, respectively (P>0.05). However, after 30 cycles of autoclave of K3, significant increase to 216±38 was identified (P<0.05). Topographic features demonstrated typical cyclic fatigue for all the groups.

CONCLUSION

The surface roughness of K3XF was increased after autoclave, while the cyclic resistance remained stable after up to 30 cycles.

Estimation of Lung Volume in Normal Population Using MSCT

OBJECTIVES

To estimate lung volume in normal population by a combination of multi-slice spiral CT and Pulmo software.

METHODS

Scans of the lung were performed on 45 normal individuals using Emotion 16-slice spiral CT and Pulmo software. A measurement instrument of work station was used to measure the vertical diameter of left and right lungs, the maximum anteroposterior and transverse diameters at the layers of apex pulmonis 1 cm below, arcus aortae, subcarinal and diaphragmatic dome, and the lung volume. Regression analysis was performed on normal lung volume and each measured parameter by SPSS 20.0 and an optimal model was selected.

RESULTS

The goodness of fit between the best curvilinear equations of the normal bilateral lung volumes was 0.981. The goodness of fit between the curvilinear equations of the normal bilateral lung volume and the product of the vertical diameter and the maximum transverse diameter of diaphragmatic dome were 0.977 and 0.972, respectively. Fifteen cases were selected to make a retrospective test on the 3 models. No significant difference was found between the estimated and measured with Pulmo software lung volumes.

CONCLUSIONS

The normal lung volume before injury can be estimated by the curvilinear equations established in this study. The percentage of lung compression can be measured based on the volume of compressed lung, which can provide a reference for the identification of lung compression degree.

[Metallurgic behavior and mechanical property of nickel-titanium endodontic files made by 3 heat treatment techniques]

Objective: To compare the phase transformation behavior, bending property and cyclic fatigue resistance of CM-wire, R-phase and M-wire nickel-titanium endodontic files treated by 3 heat treatment techniques. Methods: Hyflex CM (25 mm, 25#/0.06) made from CM wire, TF (25 mm, 25#/0.06) made from R-phase heat treatment, ProTaper Next X2 (25 mm, tip size 25#/0.06) made from M-wire, Mtwo (25 mm, 25#/0.06) and ProTaper F2 (25 mm, tip size 25#/0.08) made from conventional nickel-titanium wire were chosen. Five of each files were chosen for differential scanning calorimetric (DSC) evaluation (n=5). The specimens were prepared from adjacent portions of the shaft. The weight and length were typically (20±1) mg and 2-3 mm. Another eight of the 5 nickel-titanium files were undergone cantilever-bending test, respectively (n=8). Further ten of the 5 instruments were submitted to the cyclic fatigue test by using a simulated metal root canal (n=10). The data of M(s), M(f), A(s), A(f), ΔH, bending load, number of cyclic fatigue (NCF), fragment length were analyzed using one-way analysis of variance at a significance level of P<0.05. Results: The A(f) of Hyflex CM [(60.27±0.94) ℃] and ProTaper Next [(51.40±0.32) ℃] were higher than body temperature of 37 ℃. The bending load values at 3.0 mm deflection of Hyflex CM [(0.867±0.074) N], TF [(1.275±0.146) N], Mtwo [(2.281±0.426) N], ProTaper Next [(3.104±0.252) N] and ProTaper [(4.227±0.483) N] increased gradually and significantly. The NCF of Hyflex CM (582±99), TF (427±85), ProTaper Next (158±22), Mtwo (129±32) and ProTaper (65±20) decreased gradually. Conclusions: The 3 heat treatment techniques exert tremendous influence on the phase transformation behavior and mechanical characteristics of the files, which demonstrate improved bending property and cyclic fatigue resistance than the conventional ones.

[Impact of aortic root morphology on the implantation depth of aortic valve prosthesis during trans-catheter aortic valve replacement in patients with native bicuspid aortic valve stenosis]

Objective: To investigate the impact of aortic root morphology on the implantation depth of aortic valve prosthesis during trans-catheter aortic valve replacement (TAVR) in bicuspid aortic valve patients. Methods: Clinical data of 40 patients with native bicuspid aortic valve stenosis who underwent TAVR using the self-expandable prosthesis (the Venus A-valve) from 2014 to 2017 in Fuwai Hospital was retrospectively analyzed. The patients were divided into non-deep implantation group (implant depth ≤10 mm by instant angiogram after implantation,29 cases) and deep implantation group (implant depth> 10 mm by instant angiogram after implantation,11 cases).Pre-procedural aortic root characteristics (e.g. calcification, angle and dimensions) were assessed by CT. The impact of aortic root morphology on the implantation depth and clinical outcomes were also evaluated. Results: The age was (75.1±5.9) years with equal representation from the raphe-type and non-raphe type (52.5%(21/40) and 47.5%(19/40)).The bigger aorta angle ((56.5±4.5)° vs. (47.4±9.4)°, P=0.004),more frequent mild-calcification (HU850, <200 mm(3)) or severe-calcification(HU850, >1 000 mm(3)) of aortic leaflets (7/11 vs. 4/29, P=0.006), as well as higher ratio of left ventricular outflow tract perimeter to annulus perimeter ((109.2±7.5)% vs. (101.5±6.5)%, P=0.004) were found in the deep implantation group compared to the non-deep implantation group. The new in-hospital onset of bundle-branchheart-block or atrioventricular block conduction disturbance rate was higher in the deep implantation group than in the non-deep implantation group (6/11 vs. 2/29, P=0.030).Left ventricular ejection fraction was similar between deep implantation group and non-deep implantation group at baseline((49.9±8.9)% vs. (55.8±10.4)%, P=0.117), and was significantly lower in the deep implantation group than in the non-deep implantation group at 30 days after implantation ((51.6±12.8)% vs. (60.9±8.1)%, P=0.020). Conclusion: Aortic root morphology of bicuspid aortic valve patients is associated with implantation depth of the prosthesis during TAVR, which affects the conduction system and left ventricular function during and post TAVR.