Deep learning-based fully automatic screening of carotid artery plaques in computed tomography angiography: a multicenter study.

AIM: To develop and validate a deep learning (DL) algorithm for the automated detection and classification of carotid artery plaques (CAPs) on computed tomography angiography (CTA) images. MATERIALS AND METHODS: This retrospective study enrolled 400 patients (300 in the Center Ⅰ and 100 in Ⅱ). Three radiologists co-labeled CAPs, and their revised calcification status (noncalcified, mixed, and calcified) was regarded as ground truth. Center Ⅰ patients were randomly divided into training and internal validation datasets, while Center Ⅱ patients served as the external validation dataset. Carotid artery regions were segmented using a modified 3D-UNet network, followed by CAPs detection and classification using a ResUNet-based architecture in a two-step DL system. The DL model's detection and classification performance were evaluated on the validation dataset using precision-recall curve, free-response receiver operating characteristic (fROC) curve, Cohen's kappa, and ROC curve analysis. RESULTS: The DL model had achieved 83.4% sensitivity at 3.0 false positives (FPs)/CTA scan in internal validation and 78.9% in external validation. F1-scores were 0.764 and 0.769 at the optimal threshold, and area under fROC curves were 0.756 and 0.738, respectively, indicating good overall accuracy for CAP detection. The DL model also showed good performance for the ternary classification of CAPs, with Cohen's kappa achieved 0.728 and 0.703 in both validation datasets. CONCLUSION: This study demonstrated the feasibility of using a fully automated DL-based algorithm for the detection and ternary classification of CAPs, which could be helpful for the workloads of radiologists.

Low-dose three-dimensional CT angiography for the evaluation of posterolateral protrusion of the vertebral artery over the posterior arch of the atlas: a quantitative anatomical comparison study of the rotational and neutral positions.

AIM: To investigate the changes in relevant anatomical parameters of posterolateral protrusion of the vertebral artery (VA) between head-neck rotational and neutral positions using low-dose three-dimensional computed tomography angiography (3D-CTA). MATERIALS AND METHODS: Low-dose 3D-CTA images obtained for various craniocervical diseases in 36 non-dominant VA side patients with neutral, left and right head-neck rotational positions were evaluated. The relevant parameters from superior and inferior views, including external diameter (ED), internal diameter (ID), transverse diameter (TD), heights and diameters of posterolateral protrusion of the VA over the posterior arch of the atlas in the neutral and rotational positions, were recorded and compared. RESULTS: There was no significant differences in the rotational angle (left/right: 31.23 ± 6.60/29.94 ± 6.09°, p>0.05). There were no significant differences in heights and diameters of bilateral VA between rotational and neutral positions (all p>0.05). The contralateral ID, ED, and TD of the rotational positions were significantly shorter than those of the neutral position (all p<0.05), while there were no significant differences in the three ipsilateral diameters (all p>0.05). CONCLUSIONS: Posterolateral protrusion of the VA is not uncommon in the population, and surgeons should be aware of its presence, especially the increased possibility of injury to the VA caused by head-neck rotation, during the operation; thus, preoperative evaluation by low-dose 3D-CTA should be considered.

[Effectiveness of TRB3 on human hepatocellular carcinoma cells proliferation, apoptosis and migration].

Objective: To explore the regulatory role and mechanism of tribbles pseudokinase 3 (TRB3) on hepatocarcinoma (HCC) cells proliferation, apoptosis and migration. Methods: Immunohistochemistry and Western blot were used to detect TRB3 expression in cancerous and adjacent cancerous liver tissues of HCC patients. TRB3 expression was detected in vitro in HepG2 and Huh7 hepatocarcinoma cell lines. Simultaneously, CCK8 and EdU were used to detect cell proliferation after TRB3 targeted inhibition with small interfering RNA. CCK8 and EdU were used to detect cell proliferation. Flow cytometry assay was used to detect apoptosis. Transwell assay was used to evaluate migration ability. Simultaneously, Western blot was used to detect changes in apoptosis, migration-related proteins and AKT phosphorylation activity. The mean comparison between the two groups was performed by t-test, and the comparison between multiple groups was performed by one-way analysis of variance. Results: Western blot showed that the expression of TRB3 was significantly up-regulated in HCC tissues. Compared with normal liver tissues adjacent to cancer, the relative expression levels were 0.78 ± 0.12 and 0.29 ± 0.09, respectively, P < 0.01, and the difference was statistically significant. After interfering siRNA inhibited TRB3, CCK8 and EdU tests showed that the proliferation activity of HepG2 and Huh7 cells were significantly weakened (P < 0.05). Flow cytometry results showed that the apoptotic proportions of HepG2 and Huh7 cells was significantly increased (P < 0.01). Western blot also showed that the expression of apoptosis regulatory proteins BAX and BIM were significantly increased (P < 0.01). Transwell assay results showed that the migration ability of HepG2 and Huh7 cells was decreased (P < 0.05), and the expression of migration regulatory proteins MMP4 and MMP9 was also significantly down-regulated. Western blot results showed that the AKT phosphorylation level was significantly increased. Conclusion: TRB3 regulates hepatocarcinoma cells proliferation, apoptosis and migration by inhibiting the AKT phosphorylation activity. Therefore, TRB3 may be a potential target site for the liver cancer treatment.

Quantum Wires and Waveguides Formed in Graphene by Strain.

Confinement of electrons in graphene to make devices has proven to be a challenging task. Electrostatic methods fail because of Klein tunneling, while etching into nanoribbons requires extreme control of edge terminations, and bottom-up approaches are limited in size to a few nanometers. Fortunately, its mechanical flexibility raises the possibility of using strain to alter graphene's properties and create novel straintronic devices. Here, we report transport studies of nanowires created by linearly-shaped strained regions resulting from individual folds formed by layer transfer onto hexagonal boron nitride. Conductance measurements across the folds reveal Coulomb blockade signatures, indicating confined charges within these structures, which act as quantum dots. Along folds, we observe sharp features in traverse resistivity measurements, attributed to an amplification of the dot conductance modulations by a resistance bridge incorporating the device. Our data indicates ballistic transport up to ∼1 µm along the folds. Calculations using the Dirac model including strain are consistent with measured bound state energies and predict the existence of valley-polarized currents. Our results show that graphene folds can act as straintronic quantum wires.

[An analysis of the characteristics of perioperative cardiac troponin elevation in orthopaedic surgical patients].

Objective: Perioperative myocardial infarction remains a severe complication in non-cardiac surgery and is one of the major causes of death. Cardiac troponin (cTn) I elevation is associated with short-term and long-term mortality. The aim of the study was to assess the proportion rate of cTnI elevation and its clinical characteristics among patients admitted for orthopaedic surgery with or without cardiovascular events. Methods: This is a retrospective study including 27 744 patients aged 50 years or older who admitted for orthopaedic surgery from 2009-2015 in Beijing Jishuitan Hospital. Results: Two hundred and sixty-five patients [age (71.7±9.9) years] had cTnI level> 0.04 µg/L with 66% (175 patients) of them being female. Among them, 59 patients were isolated troponin rise (ITR) (n=59), 13 were preoperative acute myocardial infarction (AMI), and 193 were postoperative AMI. The proportion of postoperative AMI was 0.69%. Those patients were more likely to have a history of coronary artery disease or hypertension. Non-ST-segment elevation myocardial infarction (NSTEMI) was more common (93.3%) than ST-segment elevation myocardial infarction in these patients. Most of them did not experience ischemic symptoms. Totally 76.7% of the AMI occurred within 3 days of surgery; and the in-hospital mortality rate was 10.4%. Conclusions: Perioperative elevation of troponin is common in patients undergoing orthopaedic surgery. Most postoperative AMI were NSTEMI and with absent or atypical ischemia symptoms. Monitoring troponin levels and electrocardiograph in at-risk patients is needed to find most of the AMI.

[Genotyping of ABO Blood Group in Partial Population of Yunnan Province by SNaPshot Technology].

OBJECTIVES: To detect the genotype of ABO blood group by SNaPshot technology. METHODS: DNA were extracted from the peripheral blood samples with known blood groups （obtained by serology） of 107 unrelated individuals in Yunnan. Six SNP loci of the 261th, 297th, 681th, 703th, 802th, and 803th nucleotide positions were detected by SNaPshot Multiplex kit, and relevant genetics parameters were calculated. RESULTS: In 107 blood samples, the allele frequencies of types A, B, OA, and OG were 0.355 1, 0.168 2, 0.230 0 and 0.247 6, respectively, while that of types AG and cis AB were not detected. The genotyping results of ABO blood group were consistent with that of serologic testing. CONCLUSIONS: SNaPshot technology can be adapted for genotyping of ABO blood group.

Factors influencing circulating MicroRNA level in the studies of hepatocellular carcinoma biomarker.

Factors influencing circulating miRNA as a diagnostic marker of hepatocellular carcinoma (HCC) are still unknown. We used two kits to extract total RNA of 90 paired serum and plasma samples of volunteers in different statuses including healthy, hepatitis, cirrhosis and HCC. U6, miR-183 and cel-miR-39 expression levels were detected by qRT-PCR. Calculate was the relative expression level of miR-183 and recovery of cel-miR-39 with 2-∆∆CT method and standard curve method, respectively.MiRNeasy Serum/Plasma Kit was superior to miRcute miRNA Isolation Kit in the quality of the total RNA and the expression levels of U6 and miR-183, with recovery of external reference cel-miR-39 of the former in serum and plasma was the latter's 3.95-fold and 3.15-fold, respectively. The recovery of cel-miR-39 was significantly higher in serum than that in plasma in all groups except the HCC. But the trend of U6 expression of four groups in serum was different from that in plasma. There were significant differences in absorbance in 260nm, the ratio of absorbance in 260nm and 280nm (260/280), the ratio of absorbance 260nm and 230nm (260/230), the ct value of ​​U6 and the recovery of cel-miR-39 among groups in serum or plasma. Sensitivity and specificity of miR-183 as a diagnostic marker of HCC were 57.9% and 76.2% in serum, and 78.9% and 81.0% in plasma, respectively.Caution should be taken when comparing miRNA data generated from different extraction kits, sample types or disease statuses in the study of miRNA as a diagnostic marker of HCC.

Squamous cell carcinoma antigen 1 and 2 mRNA and a new variant expressed in hepatocellular carcinoma.

New tools for diagnostic of HCC remain to further investigate. We have evaluated the expression of SCCA1, 2 mRNA and their prognostic value in hepatocellular carcinoma (HCC). Reverse transcription polymerase chain reaction (RT-PCR) and direct sequencing were performed to evaluate the mRNA expression of SCCA1 and SCCA2 in 93 HCCs, and 93 paired adjacent non-cancerous tissues (PNT), 16 cirrhosis livers and 9 normal livers. The correlation of SCCA variants expression with the clinical parameters and the factors affecting survival were analyzed statistically.Total SCCA was detected in 33.3% of HCCs (31/93), in 9.68% of PNT (9/93) and 22.2% of normal livers (2/9). No expression was found in cirrhosis livers (0/16). The frequencies of total SCCA expression were significantly higher in HCCs than that in PNT and liver cirrhosis (p = 0.000, 0.006). From mRNA sequencing of HCCs, a new SCCA1 variant (presenting a T357A mutation) was identified in 16 specimens, while wild type SCCA1 was identified in 11 specimens and SCCA2 in 27 specimens. Clinicopathological analysis showed that the frequency of SCCA1 was significantly higher in poorly differentiated HCC, compared with moderately and well differentiated tumors (p = 0.021). T357A variant has a significantly higher frequency in nonencapsulated tumors than wild type SCCA1 (p = 0.034).The SCCA1, 2 mRNA is effective for detecting HCC and could be potentially applied in HCC diagnosis.

Local inversion-symmetry breaking in a bismuthate high-Tc superconductor.

The doped perovskite BaBiO3 exhibits a maximum superconducting transition temperature (Tc) of 34 K and was the first high-Tc oxide to be discovered, yet pivotal questions regarding the nature of both the metallic and superconducting states remain unresolved. Although it is generally thought that superconductivity in the bismuthates is of the conventional s-wave type, the pairing mechanism is still debated, with strong electron-phonon coupling and bismuth valence or bond disproportionation possibly playing a role. Here we use diffuse x-ray scattering and Monte Carlo modeling to study the local structure of Ba1-xKxBiO3 across its insulator-metal boundary. We find no evidence for either long- or short-range disproportionation, which resolves a major conundrum, as disproportionation and the related polaronic effects are likely not relevant for the metallic and superconducting states. Instead, we uncover nanoscale structural correlations that break inversion symmetry, with far-reaching implications for the electronic physics. This unexpected finding furthermore establishes that the bismuthates belong to the broader classes of materials with hidden spin-orbit coupling and a tendency towards inversion-breaking displacements.

[LIM-domain binding protein 2 regulated by m6A modification inhibits lung adenocarcinoma cell proliferation in vitro].

OBJECTIVE: To investigate the role and expression pattern of LIM-domain binding protein 2 (LDB2) in lung adenocarcinoma. OBJECTIVE: We studied the expression pattern of LDB2 in lung adenocarcinoma based on data from the online databases TCGA, GEO and CPTAC, and the results were verified in lung adenocarcinoma tissues and cells using immunohistochemistry, qRT-PCR and Western blotting. The relationship between LDB2 and the prognosis of patients with lung adenocarcinoma was analyzed using GEPIA and GEO databases. We further analyzed the role of LDB2 in regulating cell behaviors in a H1299 cell model over-expressing LDB2 using cell counting, soft agar colony forming assay and flow cytometry. The m6A binding sites on LDB2 were confirmed by bioinformatics analysis and MeRIP-qPCR assays. The effect of YTHDC2 on LDB2 was examined using qRT-PCR and Western blotting, and the binding of YTHDC2 to the transcript of LDB2 was verified with RIP-qPCR assays. Dual luciferase reporter assay was performed to verify YTHDC2 functioning via m6A sites. OBJECTIVE: LDB2 expression was significantly decreased in lung adenocarcinoma in comparison with normal tissues based on data from TCGA, GEPIA and CPTAC, and the same results were obtained from 80 lung adenocarcinoma tissues and 17 adjacent normal tissues. Similarly, LDB2 expression was decreased in lung adenocarcinoma cells as compared with 16HBE cells. The data from Prognoscan and GEPIA suggested that a high LDB2 expression was positively correlated with a more favorable outcome of lung adenocarcinoma patients. LDB2-overexpressing H1299 cells showed a significant inhibition of proliferative activity with cell cycle arrest in S phage. Bioinformatics analysis and MeRIP-qPCR assay confirmed the presence of m6A sites on LDB2. The m6A reader YTHDC2 was positively related with LDB2 in lung adenocarcinoma based on data from GEPIA (r=0.22). Overexpression YTHDC2 significantly enhanced LDB2 expression in H1299 cells by about 19.35 folds. Dual luciferase reporter assay showed that YTHDC2 enhanced the promoter activity in the wild-type group but not in deletion group. OBJECTIVE: LDB2 expression can be up-regulated by m6A reader YTHDC2 in lung adenocarcinoma to inhibit the proliferation of the tumor cells in vitro.

The synergistic effect of recombinant human endostatin (YH-16) combined with oxaliplatin on human colorectal carcinoma.

This study was designed to investigate the effect of recombinant human endostatin (YH-16) combined with oxaliplatin (L-OHP) on the growth of orthotopically-implanted human colorectal carcinoma in nude mice. Tumour volumes and weights were measured after therapy. Tumour cell morphology was observed by light and electron microscopy. Apoptosis was detected using the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) assay, and vascular endothelial growth factor (VEGF) expression and microvessel density (MVD) were determined by immunohistochemical staining. Tumour volumes in all treatment groups were significantly reduced compared with controls. YH-16 and L-OHP either alone or in combination caused tumour cell apoptosis, except in the YH-16 low-dose group. MVD was strongly inhibited in the treatment groups compared with the controls, although only YH-16 combined with L-OHP or L-OHP alone decreased VEGF expression. No obvious change in side-effects occurred. In conclusion, YH-16 combined with L-OHP inhibited growth and induced apoptosis in orthotopically-transplanted human colorectal carcinoma in nude mice without increasing side-effects.

LncRNA DCST1-AS1 accelerates the proliferation, metastasis and autophagy of hepatocellular carcinoma cell by AKT/mTOR signaling pathways.

OBJECTIVE: The previous research revealed that long noncoding RNAs (lncRNAs) play a vital role in the development of hepatocellular carcinoma (HCC). To further discuss the underlying mechanisms of lncRNA DCST1-AS1 in the pathogenesis of HCC. PATIENTS AND METHODS: We screened the abnormally expressed genes in HCC tissues through microarray analysis and found that lncRNA DCST1-AS1 was one of the genes significantly up-regulated. Real Time-Polymerase Chain Reaction (RT-qPCR) was used to test the gene expression of lncRNA DCST1-AS1 in HCC tissues and HepG2 cells. Respectively, CCK-8 assay, flow cytometry detection, transwell assay, wound healing assay, transmission electron microscopy, and immunofluorescence staining were used to assess the proliferation, apoptosis, migration, and autophagy of HepG2 cells. Meanwhile, the expression of signaling pathway proteins was detected by Western blot. RESULTS: LncRNA DCST1-AS1 was confirmed hyper-expression both in HCC tissues and HCC cells. High expression of lncRNA DCST1-AS1 was significantly correlated with inferior prognosis. Moreover, lncRNA DCST1-AS1 depletion suppressed proliferation and accelerated apoptosis, activated cycle arrest, restrained cell migration, and stimulated autophagy in HCC cells. In addition, it is found that the depletion of lncRNA DCST1-AS1 on HepG2 cells exhibits anti-tumor characteristics and was mediated by the AKT/mTOR signal transduction pathway. Furthermore, pre-treated HepG2 cells with SC79, an AKT signal activator, partially restored the effect of lncRNA DCST1-AS1 silencing on HepG2 cell proliferation, apoptosis, migration, and autophagy. CONCLUSIONS: Our results suggested that lncRNA DCST1-AS1, as a carcinogenic factor in HCC, promoted cell proliferation, and invasion, inhibited apoptosis and autophagy by modulating the AKT/mTOR signaling cascade. Therefore, our findings showed that lncRNA DCST1-AS1 may improve potential treatment strategies for HCC.

Silence of lncRNA XIST represses myocardial cell apoptosis in rats with acute myocardial infarction through regulating miR-449.

OBJECTIVE: To study the influences of long non-coding ribonucleic acid (lncRNA) X-inactive specific transcript (XIST) on rats with acute myocardial infarction (AMI), and its regulatory mechanism. MATERIALS AND METHODS: A total of 30 Sprague-Dawley rats were randomly assigned into Sham group, Model group, and lncRNA XIST small interfering RNA (XIST siRNA) group. The AMI rat model was prepared through ligating the left anterior descending coronary artery. The left ventricular end-diastolic volume (LVEDV), left ventricular end-systolic volume (LVESV), left ventricular systolic diameter (LVDs), and left ventricular diastolic diameter (LVDd) of rats were determined using a color Doppler ultrasound system. Reverse transcription-polymerase chain reaction was performed to measure the expression levels of lncRNA XIST, microRNA (miR)-449, and Notch1 in rat heart tissues in each group. Pathological morphology of rat heart tissues in each group was observed via hematoxylin-eosin (HE) staining. Cell apoptosis in rat heart tissues was evaluated through terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. RESULTS: Compared with those in Sham group, rats in Model group had significantly increased LVEDV, LVESV, LVDs, and LVDd. After transfection with lncRNA XIST siRNA, XIST level in rat heart tissues was remarkably declined in XIST siRNA group compared with that in Model group. According to HE staining results, the pathological injuries in rat heart tissues were greatly improved in XIST siRNA group compared with those in Model group. TUNEL staining results revealed that the apoptosis rate of cells in rat heart tissues in XIST siRNA group was markedly lower than that in Model group. Higher level of miR-449 and lower level of Notch1 were observed in rats of XIST siRNA group than those of Model group. CONCLUSIONS: Knockdown of lncRNA XIST can repress the myocardial cell apoptosis in AMI model rats by downregulating miR-449 level.

Effects of Hydrogen Gas Inhalation on Endometriosis in Rats.

OBJECTIVE: Oxidative stress is generated during the pathophysiology of endometriosis (EMT). Hydrogen (H2) has been demonstrated as a gas antioxidant. The aim of the present study is to evaluate the protective effect of H2 on EMT in rats. STUDY DESIGN: Sprague Dawley rats with surgically induced EMT were randomly received the inhalation of 67% H2-33% oxygen (O2) mixture (1 h/d, 4 weeks) immediately after the EMT surgery or 4 weeks after the operation. The mixture of 67% N2-33% O2 was also used to exclude the possible influence of the increased O2. Eight weeks after the operation, the endometrial tissues were weighted and analyzed using histology, immunohistochemistry, and real-time polymerase chain reaction. Several antioxidant enzymes and malondialdehyde were also measured in serum and tissue. The estrous cycles were monitored for H2 safety. RESULTS: The results showed that both profiles of high-dose H2 breathing reduced the size of the endometrial explants, inhibited cell proliferation, improved superoxide dismutase, glutathione peroxidase, malondialdehyde, and catalase activities, and regulated the expression of matrix metalloproteinase 9 and cyclooxygenase 2. However, inhalation of the same dose of nitrogen failed to show the protection. High-dose H2 breathing did not change the normal estrous cyclicity. CONCLUSION: These results suggest that 67% H2-33% O2 breathing has a beneficial effect on EMT model rats, and inhalation of a high dose of H2 could be a potential method applied in clinical practice.

Characterization of tBid-induced cytochrome c release from mitochondria and liposomes.

tBid, the cleaved form of Bid, can induce cytochrome c (Cyt. c) release from rat heart mitochondria more efficiently and reproducibly than that from liver or brain mitochondria. Unlike Bax, such release was not prevented by cyclosphorin A, an inhibitor of the opening of permeability transition pore. Carbonyl-cyanide m-chlorophenyl-hydrazone or oligomycin also have no obvious effect on the release of Cyt. c. In contrast to ceramide, tBid-mediated Cyt. c release from mitochondria is independent of the redox state of Cyt. c. Furthermore, Bid or tBid can directly trigger the efflux of encapsulated Cyt. c or trypsin within liposomes without involvement of other protein factors.

[Observation on application of solid phase indirect hemadsorption assay for detection IgM antibodies to tuberculosis in non-serum specimens].

We used solid phase indirect hemadsorption assay (SPIHA) to detect specific IgM antibodies in specimens from cerebrospinal fluid, pleural fluid and ascitic fluid in patients with tuberculosis and compared with the enzyme linked immunosorbent assay (ELISA) and indirect hemagglutination assay (IHA). The result showed that detection of tuberculous specific IgM antibodies in cerebrospinal fluid by SPIHA is important for diagnosing the tuberculous meningitis.

[Anterior interbody autografting and internal fixation for primary surgical management of thoracolumbar spinal tuberculosis].

OBJECTIVES: To verify the importance of early reconstruction of spinal stability and to evaluate the safety of anterior instrumentation in surgical management of spinal tuberculosis. METHODS: Eleven cases of thoracolumbar spinal tuberculosis were treated with primary anterior debridement, interbody autografting and Z-plate fixation from October 1997 to January 1999. RESULTS: All the 11 cases healed without any recurrence after follow-up for an average of 16 months. Spinal fusion occurred in 3.8 months on average after surgery. 18 degrees of kyphosis correction was achieved with no associated complication. CONCLUSIONS: Early reconstruction of spinal stability plays an important role in surgical management of spinal tuberculosis, and it is safe to implant anterior titanium spinal instrument in tuberculosis foci.

[Signal multiplier spectrophotometric determination of baicalin, chlorogenic acid and phillyrin in shuang huanglian injection].

Signal multiplier spectrophotometry was used for the determination of baicalin, chlorogenic acid and phillyrin in Shuang Huanglian injection. The method can eliminate interference without preliminary separation and has proved simple, speedy and accurate.

[Heart morphologic state in retired fighter pilots].

Objective. To study the heart morphology in the retired fighter pilots, and to provide clinical evidence for protection combined G-loads (+ Gz), heat, noise, hypoxic and vibration stress induced cardiac structural damage. Method. Parameters of heart morphology were studied using Doppler echocardiography in 40 retired fighter pilots with 40 veteran cadres as control. Result. LVDd, LVDs, LADs, LVEDV, LVPWs and LVM in pilot group were somewhat higher than those in control group (NS); while IVSs and LVMI in pilot group were slightly lower than those in control group (NS); LVESV, aortic valve area, internal diameter of the ring and sinus in pilot group were significantly higher than those in control group (P < 0.05). Conclusion. Analysis of the results revealed no pathomorphologic damage of the heart. It suggest that all the variations can be regarded as adaptive changes due to the effects of the combined environmental factors experienced in long time flying.

Three-dimensional structure of Bax-mediated pores in membrane bilayers.

B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) is a member of the Bcl-2 protein family having a pivotal role in triggering cell commitment to apoptosis. Bax is latent and monomeric in the cytosol but transforms into its lethal, mitochondria-embedded oligomeric form in response to cell stress, leading to the release of apoptogenic factors such as cytochrome C. Here, we dissected the structural correlates of Bax membrane insertion while oligomerization is halted. This strategy was enabled through the use of nanometer-scale phospholipid bilayer islands (nanodiscs) the size of which restricts the reconstituted system to single Bax-molecule activity. Using this minimal reconstituted system, we captured structural correlates that precede Bax homo-oligomerization elucidating previously inaccessible steps of the core molecular mechanism by which Bcl-2 family proteins regulate membrane permeabilization. We observe that, in the presence of BH3 interacting domain death agonist (Bid) BH3 peptide, Bax monomers induce the formation of ~3.5-nm diameter pores and significantly distort the phospholipid bilayer. These pores are compatible with promoting release of ions as well as proteinaceous components, suggesting that membrane-integrated Bax monomers in the presence of Bid BH3 peptides are key functional units for the activation of the cell demolition machinery.