Pericoronary adipose tissue attenuation predicts outcome of percutaneous intervention for chronic total occlusion

AIM

To investigate the association between pericoronary adipose tissue (PCAT) attenuation (PCATA) and outcomes of chronic total occlusion (CTO) after percutaneous coronary intervention (PCI), and to establish a clinical model that can be easily generalised to predict the outcomes of PCI-CTO.

MATERIALS AND METHODS

Between September 2015 and September 2019, patients from two centres were enrolled retrospectively. The primary endpoint was a procedural success (defined as achieving residual stenosis of <30% and a grade 3 thrombolysis in myocardial infarction [TIMI] flow). The new predictive model was generated by factors that were determined by multivariate analysis. The PCATA of CTO (PCATA-CTO) score was developed by assigning 1 point for each independent predictor, and then summing all points accrued. In addition, the predictive efficacy and interobserver and intraobserver agreement of PCATA-CTO and other scoring systems based on coronary computed tomography angiography (CCTA) were compared.

RESULTS

A total of 201 patients (mean age 58.9 ± 10.8 years, 85% male) were enrolled. The PCI success was achieved in 76% of the lesions. PCAT was higher in the PCI success group (-72.44 ± 10.45HU versus -76.76 ± 10.54 HU, p<0.05). Multivariable analysis yielded severe calcification, lesion length ≥15 mm, and perivascular fat attenuation index (FAI) ≤-69.5HU as independent negative predictors for procedural success. The area under the receiver operating characteristic curves for the PCATA-CTO score was 0.72. Comparing the PCATA-CTO score with other predictive scores, the PCATA-CTO score showed the highest interobserver (kappa = 0.74) and intraobserver agreement (kappa = 0.90, all p<0.01).

CONCLUSION

FAI ≤-69.5HU is an independent negative predictor of procedural success. The PCATA-CTO score improved the reliability of the prediction model. Its potential for clinical implementation requires evaluation.

Effects of Yi Jin Jing on juvenile cervical spondylopathy in China: A parallel, randomized, assessor-blinded clinical trial

Background

Cervical spondylopathy is a common musculo-articular disorder, multiple exercises are recommended. Chinese fitness exercises are prevalent and used to treat various diseases.

Aim

To explore the efficacy of Chinese fitness exercise Yi Jin Jing exercise in intervening the cervical spondylopathy in adolescents.

Patients and Methods

The study was conducted in 60 adolescent patients with cervical spondylopathy, with 30 patients in each group.

Methods

The study was conducted in 60 adolescent patients with cervical spondylopathy, with 30 patients in each group. The observation group was required to take Yi Jin Jing exercise, and the control group took the brisk walking exercise. The first week was the preparatory period for the patients, and then the participants were required to do exercises three times a week for at least 30 minutes in the later 3 weeks. Before and after treatment, Neck Disability Index (NDI) scores, pain visual analog scale (VAS) scores, and cervical curvature in both groups were observed, and the incidence of adverse events in both groups was recorded during the trial.

Results

The NDI and VAS scores in both groups statistically decreased after intervention and mildly increased at follow-up, while the reduction in scores of the Yi Jin Jing group was more significant. Cervical curvature in both groups improved on day 28 compared to day 0. There were no adverse reactions during the evaluation period.

Conclusion

The Chinese health-care qigong Yi Jin Jing exercise is more effective than brisk walking in improving the cervical range of motion and relieving pain in adolescents with cervical spondylopathy. Trial registration/Protocol registration: Clinical Trial Registry (ChiCTR2000030723).

Giant Malignant Meningioma Penetrates the Skull

Meningioma is a primary tumor of the central nervous system, most commonly found in the middle-aged and elderly. Most meningiomas are benign, whereas malignant meningiomas account for only 1% of all meningiomas. Meningiomas usually grow slowly, and patients often have headaches and epilepsy as the first symptoms. According to the location of the tumor, there can also be vision, visual field, olfactory, hearing impairment, and so on. Surgery is the main treatment. A case of giant malignant meningioma penetrating the skull is reported. The patient was a 67-year-old male with a left parietal scalp mass about 1 year ago, which gradually enlarged to the size of 6×6 cm and had no other symptoms. Imaging examination showed that the tumor eroded the skull, and the density was uneven. After surgical resection (Simpson grade I), poorly differentiated meningioma (World Health Organization Grade Ⅲ) was returned pathologically. After operation, the patient recovered well.

A few-shot learning-based eye diseases screening method

OBJECTIVE

This study aims to construct a brand-new ophthalmic disease screening task and establish a practically valuable ophthalmic disease screening model in the case of insufficient data.

MATERIALS AND METHODS

The main methods are as follows: firstly, we mixed data from different sources (these data may come from different cameras, including different fundus diseases) to get a new dataset. Based on this dataset, we conducted subsequent experiments on fundus multi-disease screening. However, in the past public datasets, each dataset often only corresponded to the screening diagnosis of one disease. Secondly, we proposed a method to simulate the characteristics of different fundus cameras by using a method based on style transfer, and to augment the training data, so that the model could learn the features of ophthalmic diseases in a more comprehensive way. Finally, a robust disease screening model based on few-shot learning was constructed on the combined dataset, and compared with benchmark algorithms.

RESULTS

We focused on the study of eye disease screening methods based on the metric-based few-shot learning model, data augmentation methods, and focus on key technologies such as data augmentation based on style transfer. Experiments have shown that our method can significantly improve the generalization ability of the disease screening model.

CONCLUSIONS

By introducing few-shot learning theory and data augmentation based on style transfer into ophthalmic disease screening, the generalization ability of the model is greatly improved, and it has certain practical value.

[Effects of pretreatment HIV drug resistance on the virological response of HIV-infected patients after 3-year antiretroviral therapy]

Objective: To investigate the impact of pretreatment drug resistance (PDR) on virological effect among HIV-infected patients having received antiretroviral therapy (ART) after three years. Methods: The baseline survey of PDR among HIV-infected patients was conducted in 2018, with a three-year follow up study. The clinic data and virological laboratory test variables were statistically analyzed. Results: Of the 2 433 participants, 41.6% (1 012/2 433) were aged between 18 and 34, 82.8% (2 015/2 433) were males, 46.9% (1 142/2 433) had education of high school or above, 22.4% (544/2 433) were farmers, 33.8% (823/2 433) were unmarried, 48.1% (1 169/2 433) were infected heterosexually and 41.3% (1 004/2 433) were with CRF07_BC. The prevalence of PDR was 4.5% (109/2 433). The prevalence of virological suppression failure (viral load ≥50 copies/ml) and drug resistance at three years follow up after ART was 8.1%(196/2 433) and 2.5%(60/2 433) respectively. The prevalence of virological suppression failure and drug resistance at three years follow up after ART were 18.3% (20/109) and 7.6% (176/2 324), and 4.6% (5/109) and 2.4% (55/2 324) among participants with PDR and non-PDR, respectively. The results of multivariate logistic regression model showed that illiteracy (aOR=3.26, 95%CI: 1.82-5.86), primary and junior high school education (aOR=1.54, 95%CI: 1.09-2.18), CD4⁺T lymphocyte count <200/μl (aOR=2.77, 95%CI: 1.75-4.37) and CD4⁺T lymphocyte count 200-499/μl (aOR=1.55, 95%CI: 1.10-2.18) at a three year follow up visit after ART, missed drugs in the past month (aOR=4.24, 95%CI: 2.92-6.17), and PDR (aOR=2.84, 95%CI: 1.67-4.85) were statistically significant with virological suppression failure on treatment. Conclusions: The prevalence of PDR in China at a low level currently, and the virological suppression failure rate is low after three years of ART. It is necessary to strengthen drug resistance monitoring of HIV-infected patients and pay attention to the influence of PDR on treatment effect.

[Factors associated with death and attrition in HIV-infected children under initial antiretroviral therapy in Guangxi Zhuang Autonomous Region, 2004 - 2019]

Objective: To investigate death and attrition in HIV-infected children under initial antiretroviral therapy (ART) and associated factors in Guangxi Zhuang autonomous region. Methods: This retrospective cohort study was conducted in HIV-infected children under initial ART in Guangxi from 2004 to 2019, data from ART information system of National comprehensive AIDS prevention and treatment information system. Cox proportional hazards models were used to assess factors associated with the death and attrition. Results: In 943 HIV-infected children, the overall mortality and attrition rates were 1.00/100 person-years and 0.77/100 person-years, respectively. The mortality and attrition rates within the first year of ART were 3.90/100 person-years and 1.67/100 person-years, respectively. The cumulative survival rate during the first, second, fifth and tenth year after ART was 96.14%, 95.80%, 93.68% and 91.54%, respectively. Multivariate Cox proportional hazards models results showed that being female (aHR=2.00, 95%CI: 1.17-3.40), CD4⁺T lymphocytes (CD4) counts before ART <200 cells/μl (aHR=2.79, 95%CI: 1.54-5.06), weight-for-age Z score before ART <-2 (aHR=2.38, 95%CI: 1.32-4.26), hemoglobin before ART <80 g/L (aHR=2.47, 95%CI: 1.24-4.92), initial ART with LPV/r (aHR=5.05, 95%CI: 1.15-22.12) were significantly associated with death; being female (aHR=2.23, 95%CI: 1.22-4.07) and initial ART with LPV/r (aHR=2.02, 95%CI: 1.07-3.79) were significantly associated with attrition. Conclusions: The effect of ART in HIV-infected children in Guangxi was better, but the mortality and attrition rates were high within the first year of treatment. It is necessary to strengthen the training in medical staff and health education in HIV-infected children and their parents in order to improve the treatment effect.

[The clinical effect and imaging features of accordion maneuver in promoting bone healing at the docking site after tibial transport under ultrasonic monitoring]

Objective: To explore the imaging features and clinical effect of accordion maneuver in promoting the bone healing at the docking site after tibial transport under ultrasonic monitoring. Methods: Retrospective analysis was conducted on the clinical data of 16 patients with tibial bone transport who were admitted to the Department of Orthopedics, the second Hospital of Shanxi Medical University from May 2018 to October 2019. All the patients were treated with accordion maneuver to promote bone healing at the docking site under ultrasound monitoring. There were 14 males and 2 females, aged (45.3±14.3) years (range: 6 to 61 years). Before tibial bone transport, the length of the tibial defect of 16 patients was (6.0±2.6) cm (range: 2.0 to 12.1 cm). The operation steps of accordion maneuver were as follows: pressurization for 2 weeks, suspension for 12 days, distraction for 2 weeks, retraction for 2 weeks, and then stop the operation to consolidate the bone mineralization. During accordion treatment, ultrasound was used to monitor the size of hematoma, Adler grade of blood flow signal and the changes of new callus in and around the docking site. X-ray was performed to monitor bone healing at the docking site. Pearson correlation coefficient was used to analyze the correlation between the size of hematoma, the resistance index of blood flow signal and the bone healing time of the docking site. Paley healing criterion was used to evaluate the bone healing and functional recovery of the patients. Results: During accordion maneuver, ultrasound examination showed that the Adler grade of blood flow signals around the docking site increased gradually before retraction and then decreased gradually, but the degree of callus mineralization continued to increase gradually. After 2 weeks of pressure on the docking site, hematoma was observed in 14 patients by ultrasound examination. X-ray showed that all docking sites had bony healing, with the healing time of (30.8±4.9) weeks (range: 23 to 40 weeks).The size of the hematoma was negatively correlated with the healing time of the docking site (r=-0.819,P<0.01). No hematoma was found in 2 patients, and after continuous observation for 20 weeks, there was still no obvious callus connection at the docking site. After bone cortical removal, ultrasound examination showed hematoma formed at the docking site. Accordion maneuver was continued, and the docking site healed at 30 and 32 weeks after surgery, respectively. There was a negative linear correlation between hematoma size at 2 weeks of compression and the blood flow resistance index at 2 weeks of retraction in 16 patients (r=-0.801, P<0.01). The patients were followed-up for (14.5±3.2) months (range: 10.6 to 20.2 months). At the last follow-up, 12 patients were evaluated as excellent and 4 were evaluated as good by Paley healing criteria. Conclusion: The distraction and compression stress applied in accordion maneuver can promote bone healing at the docking site, and ultrasound can monitor early signs of bone healing at the docking site to help determine the tendency of bone healing.

[Influencing factors on the death of HIV/AIDS patients treated with antiviral treatment in Butuo county, Liangshan Yi Autonomous Prefecture, 2010-2019]

Objective: To understand influencing factors on the deaths of HIV/AIDS patients receiving antireviral treatment in Butuo county of Liangshan Yi Autonomous Prefecture (Liangshan) from 2010 to 2019, to provide data for drug replacement and sustainable antiviral treatment strategy. Methods: A matched case-control study was used to collect basic and follow-up information on AIDS death patients receiving antiviral treatment in Butuo county of Liangshan from 2010 to 2019. The control group was formed by sampling twice the number of cases. The logistic regression model was used to analyze the risk factors affecting mortality. Results: In 3 355 patients of HIV/AIDS treated with antiviral therapy, 1 179 cases in the death group and 2 176 cases in the control group. Including 81.34% were 30-49 years old, 69.09％males, 99.55% Yi nationality, 91.12% were married or cohabitated, 95.77% had junior high school education or below, and 88.41% peasants. Amultivariate logistic stepwise regression model showed that among the death risk factors, age ≥50 years old was 5.08 times (95%CI:3.05-8.48) that of the 18-29, female was 0.70 times (95%CI: 0.52-0.94) than male, the transmission rate of intravenous drug use was 1.43 times (95%CI: 1.06-1.91) that of heterosexual transmission, CD4⁺T lymphocyte (CD4) count ≥350 cells/μl before treatment was 0.38 times (95%CI: 0.30-0.48) that of CD4 <200 cells/μl before treatment, the most recent antiviral treatment regimen containing LPV/r was 0.04 times (95%CI: 0.01-0.18) than that of stavudine (d4T) + lamivudine (3TC) + nevirapine (NVP)/efavirenz (EFV) regimen, drug resistance was 3.40 times (95%CI: 2.13-5.42) of non-drug resistance, non-viral load and non-drug resistance test results were 12.98 times (95%CI: 10.28-16.40) of non-drug resistance. Conclusions: Age, gender, transmission route, CD4 before treatment, the latest antiviral treatment program, and drug resistance test after antiviral therapy were the influencing factors of HIV/AIDS death in Butuo county. It is necessary to expand the coverage of viral load and drug resistance test to change the antiviral therapeutic schedule scientifically and carry out publicity and education on the compliance of patients with antiviral treatment and medical staff training in order to reduce the mortality of patients with antiviral treatment.

Observation of Multiplicity Dependent Prompt χ_{c1}(3872) and ψ(2S) Production in pp Collisions

The production of χ_{c1}(3872) and ψ(2S) hadrons is studied as a function of charged particle multiplicity in pp collisions at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 2  fb^{-1}. For both states, the fraction that is produced promptly at the collision vertex is found to decrease as charged particle multiplicity increases. The ratio of χ_{c1}(3872) to ψ(2S) cross sections for promptly produced particles is also found to decrease with multiplicity, while no significant dependence on multiplicity is observed for the equivalent ratio of particles produced away from the collision vertex in b-hadron decays. This behavior is consistent with a calculation that models the χ_{c1}(3872) structure as a compact tetraquark. Comparisons with model calculations and implications for the binding energy of the χ_{c1}(3872) state are discussed.

Model-Independent Study of Structure in B^{+}→D^{+}D^{-}K^{+} Decays

The only anticipated resonant contributions to B^{+}→D^{+}D^{-}K^{+} decays are charmonium states in the D^{+}D^{-} channel. A model-independent analysis, using LHCb proton-proton collision data taken at center-of-mass energies of sqrt[s]=7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9  fb^{-1}, is carried out to test this hypothesis. The description of the data assuming that resonances only manifest in decays to the D^{+}D^{-} pair is shown to be incomplete. This constitutes evidence for a new contribution to the decay, potentially one or more new charm-strange resonances in the D^{-}K^{+} channel with masses around 2.9  GeV/c^{2}.

Constraints on the K_{S}^{0}→μ^{+}μ^{-} Branching Fraction

A search for the decay K_{S}^{0}→μ^{+}μ^{-} is performed using proton-proton collision data, corresponding to an integrated luminosity of 5.6  fb^{-1} and collected with the LHCb experiment during 2016, 2017, and 2018 at a center-of-mass energy of 13 TeV. The observed signal yield is consistent with zero, yielding an upper limit of B(K_{S}^{0}→μ^{+}μ^{-})<2.2×10^{-10} at 90% C.L.. The limit reduces to B(K_{S}^{0}→μ^{+}μ^{-})<2.1×10^{-10} at 90% C.L. once combined with the result from data taken in 2011 and 2012.

Observation of Enhanced Double Parton Scattering in Proton-Lead Collisions at sqrt[s_{NN}]=8.16 TeV

A study of prompt charm-hadron pair production in proton-lead collisions at sqrt[s_{NN}]=8.16  TeV is performed using data corresponding to an integrated luminosity of about 30  nb^{-1}, collected with the LHCb experiment. Production cross sections for different pairs of charm hadrons are measured and kinematic correlations between the two charm hadrons are investigated. This is the first measurement of associated production of two charm hadrons in proton-lead collisions. The results confirm the predicted enhancement of double parton scattering production in proton-lead collisions compared to the single parton scattering production.

Measurement of CP-Averaged Observables in the B^{0}→K^{*0}μ^{+}μ^{-} Decay

An angular analysis of the B^{0}→K^{*0}(→K^{+}π^{-})μ^{+}μ^{-} decay is presented using a dataset corresponding to an integrated luminosity of 4.7  fb^{-1} of pp collision data collected with the LHCb experiment. The full set of CP-averaged observables are determined in bins of the invariant mass squared of the dimuon system. Contamination from decays with the K^{+}π^{-} system in an S-wave configuration is taken into account. The tension seen between the previous LHCb results and the standard model predictions persists with the new data. The precise value of the significance of this tension depends on the choice of theory nuisance parameters.

Observation of New Ξ_{c}^{0} Baryons Decaying to Λ_{c}^{+}K^{-}

The Λ_{c}^{+}K^{-} mass spectrum is studied with a data sample of pp collisions at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 5.6  fb^{-1} collected by the LHCb experiment. Three Ξ_{c}^{0} states are observed with a large significance and their masses and natural widths are measured to be m[Ξ_{c}(2923)^{0}]=2923.04±0.25±0.20±0.14  MeV, Γ[Ξ_{c}(2923)^{0}]=7.1±0.8±1.8  MeV, m[Ξ_{c}(2939)^{0}]=2938.55±0.21±0.17±0.14  MeV, Γ[Ξ_{c}(2939)^{0}]=10.2±0.8±1.1  MeV, m[Ξ_{c}(2965)^{0}]=2964.88±0.26±0.14±0.14  MeV, Γ[Ξ_{c}(2965)^{0}]=14.1±0.9±1.3  MeV, where the uncertainties are statistical, systematic, and due to the limited knowledge of the Λ_{c}^{+} mass. The Ξ_{c}(2923)^{0} and Ξ_{c}(2939)^{0} baryons are new states. The Ξ_{c}(2965)^{0} state is in the vicinity of the known Ξ_{c}(2970)^{0} baryon; however, their masses and natural widths differ significantly.

Search for the Rare Decays B_{s}^{0}→e^{+}e^{-} and B^{0}→e^{+}e^{-}

A search for the decays B_{s}^{0}→e^{+}e^{-} and B^{0}→e^{+}e^{-} is performed using data collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to integrated luminosities of 1, 2, and 2  fb^{-1}, respectively. No signal is observed. Assuming no contribution from B^{0}→e^{+}e^{-} decays, an upper limit on the branching fraction B(B_{s}^{0}→e^{+}e^{-})<9.4(11.2)×10^{-9} is obtained at 90(95)% confidence level. If no B_{s}^{0}→e^{+}e^{-} contribution is assumed, a limit of B(B^{0}→e^{+}e^{-})<2.5(3.0)×10^{-9} is determined at 90(95)% confidence level. These upper limits are more than one order of magnitude lower than the previous values.

Measurement of f_{s}/f_{u} Variation with Proton-Proton Collision Energy and B-Meson Kinematics

The ratio of the B_{s}^{0} and B^{+} fragmentation fractions f_{s} and f_{u} is studied with B_{s}^{0}→J/ψϕ and B^{+}→J/ψK^{+} decays using data collected by the LHCb experiment in proton-proton collisions at 7, 8, and 13 TeV center-of-mass energies. The analysis is performed in bins of B-meson momentum, longitudinal momentum, transverse momentum, pseudorapidity, and rapidity. The fragmentation-fraction ratio f_{s}/f_{u} is observed to depend on the B-meson transverse momentum with a significance of 6.0σ. This dependency is driven by the 13 TeV sample (8.7σ), while the results for the other collision energies are not significant when considered separately. Furthermore, the results show a 4.8σ evidence for an increase of f_{s}/f_{u} as a function of collision energy.

Isospin Amplitudes in Λ_{b}^{0}→J/ψΛ(Σ^{0}) and Ξ_{b}^{0}→J/ψΞ^{0}(Λ) Decays

Ratios of isospin amplitudes in hadron decays are a useful probe of the interplay between weak and strong interactions and allow searches for physics beyond the standard model. We present the first results on isospin amplitudes in b-baryon decays, using data corresponding to an integrated luminosity of 8.5  fb^{-1}, collected with the LHCb detector in pp collisions at center of mass energies of 7, 8, and 13 TeV. The isospin amplitude ratio |A_{1}(Λ_{b}^{0}→J/ψΣ^{0})/A_{0}(Λ_{b}^{0}→J/ψΛ)|, where the subscript on A indicates the final-state isospin, is measured to be less than 1/21.8 at 95% confidence level. The Cabibbo suppressed Ξ_{b}^{0}→J/ψΛ decay is observed for the first time, allowing for the measurement |A_{0}(Ξ_{b}^{0}→J/ψΛ)/A_{1/2}(Ξ_{b}^{0}→J/ψΞ^{0})|=0.37±0.06±0.02, where the uncertainties are statistical and systematic, respectively.

First Observation of Excited Ω_{b}^{-} States

We report four narrow peaks in the Ξ_{b}^{0}K^{-} mass spectrum obtained using pp collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9  fb^{-1} recorded by the LHCb experiment. Referring to these states by their mass, the mass values are m[Ω_{b}(6316)^{-}]=6315.64±0.31±0.07±0.50  MeV, m[Ω_{b}(6330)^{-}]=6330.30±0.28±0.07±0.50  MeV, m[Ω_{b}(6340)^{-}]=6339.71±0.26±0.05±0.50  MeV, m[Ω_{b}(6350)^{-}]=6349.88±0.35±0.05±0.50  MeV, where the uncertainties are statistical, systematic, and the last is due to the knowledge of the Ξ_{b}^{0} mass. The natural widths of the three lower mass states are consistent with zero, and the 90% confidence-level upper limits are determined to be Γ[Ω_{b}(6316)^{-}]<2.8  MeV, Γ[Ω_{b}(6330)^{-}]<3.1  MeV and Γ[Ω_{b}(6340)^{-}]<1.5  MeV. The natural width of the Ω_{b}(6350)^{-} peak is 1.4_{-0.8}^{+1.0}±0.1  MeV, which is 2.5σ from zero and corresponds to an upper limit of 2.8 MeV. The peaks have local significances ranging from 3.6σ to 7.2σ. After accounting for the look-elsewhere effect, the significances of the Ω_{b}(6316)^{-} and Ω_{b}(6330)^{-} peaks are reduced to 2.1σ and 2.6σ, respectively, while the two higher mass peaks exceed 5σ. The observed peaks are consistent with expectations for excited Ω_{b}^{-} resonances.

Search for A^{'}→μ^{+}μ^{-} Decays

Searches are performed for both promptlike and long-lived dark photons, A^{'}, produced in proton-proton collisions at a center-of-mass energy of 13 TeV. These searches look for A^{'}→μ^{+}μ^{-} decays using a data sample corresponding to an integrated luminosity of 5.5  fb^{-1} collected with the LHCb detector. Neither search finds evidence for a signal, and 90% confidence-level exclusion limits are placed on the γ-A^{'} kinetic mixing strength. The promptlike A^{'} search explores the mass region from near the dimuon threshold up to 70 GeV and places the most stringent constraints to date on dark photons with 214<m(A^{'})≲740  MeV and 10.6<m(A^{'})≲30  GeV. The search for long-lived A^{'}→μ^{+}μ^{-} decays places world-leading constraints on low-mass dark photons with lifetimes O(1)  ps.

Observation of Several Sources of CP Violation in B^{+}→π^{+}π^{+}π^{-} Decays

Observations are reported of different sources of CP violation from an amplitude analysis of B^{+}→π^{+}π^{+}π^{-} decays, based on a data sample corresponding to an integrated luminosity of 3  fb^{-1} of pp collisions recorded with the LHCb detector. A large CP asymmetry is observed in the decay amplitude involving the tensor f_{2}(1270) resonance, and in addition significant CP violation is found in the π^{+}π^{-}S wave at low invariant mass. The presence of CP violation related to interference between the π^{+}π^{-}S wave and the P wave B^{+}→ρ(770)^{0}π^{+} amplitude is also established; this causes large local asymmetries but cancels when integrated over the phase space of the decay. The results provide both qualitative and quantitative new insights into CP -violation effects in hadronic B decays.

Search for Lepton-Flavor Violating Decays B^{+}→K^{+}μ^{±}e^{∓}

A search for the lepton-flavor violating decays B^{+}→K^{+}μ^{±}e^{∓} is performed using a sample of proton-proton collision data, collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of 3  fb^{-1}. No significant signal is observed, and upper limits on the branching fractions are set as B(B^{+}→K^{+}μ^{-}e^{+})<7.0(9.5)×10^{-9} and B(B^{+}→K^{+}μ^{+}e^{-})<6.4(8.8)×10^{-9} at 90% (95)% confidence level. The results improve the current best limits on these decays by more than one order of magnitude.

Measurement of Charged Hadron Production in Z-Tagged Jets in Proton-Proton Collisions at sqrt[s]=8 TeV

The production of charged hadrons within jets recoiling against a Z boson is measured in proton-proton collision data at sqrt[s]=8  TeV recorded by the LHCb experiment. The charged-hadron structure of the jet is studied longitudinally and transverse to the jet axis for jets with transverse momentum p_{T}>20  GeV and in the pseudorapidity range 2.5<η<4. These are the first measurements of jet hadronization at these forward rapidities and also the first where the jet is produced in association with a Z boson. In contrast to previous hadronization measurements at the Large Hadron Collider, which are dominated by gluon jets, these measurements probe predominantly light-quark jets which are found to be more longitudinally and transversely collimated with respect to the jet axis when compared to the previous gluon dominated measurements. Therefore, these results provide valuable information on differences between quarks and gluons regarding nonperturbative hadronization dynamics.

Search for the Lepton-Flavor-Violating Decays B_{s}^{0}→τ^{±}μ^{∓} and B^{0}→τ^{±}μ^{∓}

Results are reported from a search for the rare decays B_{s}^{0}→τ^{±}μ^{∓} and B^{0}→τ^{±}μ^{∓}, where the τ lepton is reconstructed in the channel τ^{-}→π^{-}π^{+}π^{-}ν_{τ}. These processes are effectively forbidden in the standard model, but they can potentially occur at detectable rates in models of new physics that can induce lepton-flavor-violating decays. The search is based on a data sample corresponding to 3  fb^{-1} of proton-proton collisions recorded by the LHCb experiment in 2011 and 2012. The event yields observed in the signal regions for both processes are consistent with the expected standard model backgrounds. Because of the limited mass resolution arising from the undetected τ neutrino, the B_{s}^{0} and B^{0} signal regions are highly overlapping. Assuming no contribution from B^{0}→τ^{±}μ^{∓}, the upper limit B(B_{s}^{0}→τ^{±}μ^{∓})<4.2×10^{-5} is obtained at 95% confidence level. If no contribution from B_{s}^{0}→τ^{±}μ^{∓} is assumed, a limit of B(B^{0}→τ^{±}μ^{∓})<1.4×10^{-5} is obtained at 95% confidence level. These results represent the first limit on B(B_{s}^{0}→τ^{±}μ^{∓}) and the most stringent limit on B(B^{0}→τ^{±}μ^{∓}).

Observation of New Resonances in the Λ_{b}^{0}π^{+}π^{-} System

We report the observation of a new structure in the Λ_{b}^{0}π^{+}π^{-} spectrum using the full LHCb data set of pp collisions, corresponding to an integrated luminosity of 9  fb^{-1}, collected at sqrt[s]=7, 8, and 13 TeV. A study of the structure suggests its interpretation as a superposition of two almost degenerate narrow states. The masses and widths of these states are measured to be m_{Λ_{b}(6146)^{0}}=6146.17±0.33±0.22±0.16  MeV,m_{Λ_{b}(6152)^{0}}=6152.51±0.26±0.22±0.16  MeV,Γ_{Λ_{b}(6146)^{0}}=2.9±1.3±0.3  MeV,Γ_{Λ_{b}(6152)^{0}}=2.1±0.8±0.3  MeV,with a mass splitting of Δm=6.34±0.32±0.02  MeV, where the first uncertainty is statistical, the second systematic. The third uncertainty for the mass measurements derives from the knowledge of the mass of the Λ_{b}^{0} baryon. The measured masses and widths of these new excited states suggest their possible interpretation as a doublet of Λ_{b}(1D)^{0} states.

Hydrogen sulphide production by Saccharomyces cerevisiae UCD 522 in a synthetic grape juice medium deficient of thiamin (vitamin B1 ) and/or pyridoxine (vitamin B6 )

The impacts of thiamin and pyridoxine along with YAN on alcoholic fermentation and hydrogen sulphide production by Saccharomyces cerevisiae were studied. Using a synthetic grape juice medium, three fermentation trials were conducted; (i) 2 × 3 factorial design with thiamin (0, 0·2, or 0·5 mg l^-1 ) and YAN (60 or 250 mg l^-1 ) as variables, (ii) 2 × 3 factorial design with pyridoxine (0, 0·25, or 0·5 mg l^-1 ) and YAN (60 or 250 mg l^-1 ) as variables, and (iii) 3 × 3 factorial design with thiamin (0, 0·2 or 0·5 mg l^-1 ) and pyridoxine (0, 0·25 or 0·5 mg l^-1 ) as variables in media containing 60 mg l^-1 YAN. Although the progress of fermentations was affected by thiamin or pyridoxine, YAN had a larger impact than either vitamin. H₂ S production was significantly lower with increasing amounts of thiamin in those fermentations under low YAN (60 mg l^-1 ) while even lower amounts (<30 µg l^-1 ) were produced under high YAN (250 mg l^-1 ) with or without the vitamin. The highest amounts of H₂ S were synthesized in those fermentations without any pyridoxine (>110 µg l^-1 ), with the lowest production in media with pyridoxine and high YAN (<20 µg l^-1 ). SIGNIFICANCE AND IMPACT OF THE STUDY: Concentrations of thiamin, pyridoxine and yeast assimilable nitrogen (YAN) influenced the synthesis of hydrogen sulphide (H₂ S) by Saccharomyces cerevisiae in a synthetic grape juice medium. With a few exceptions, an increase in the concentration of either vitamin or YAN resulted in less H₂ S released. This is the first report to demonstrate that both thiamin and pyridoxine along with YAN affected H₂ S production, emphasizing the need to assess yeast nutrients to lower risks of off-odours during fermentation.

Measurement of CP-Violating and Mixing-Induced Observables in B_{s}^{0}→ϕγ Decays

A time-dependent analysis of the B_{s}^{0}→ϕγ decay rate is performed to determine the CP -violating observables S_{ϕγ} and C_{ϕγ} and the mixing-induced observable A_{ϕγ}^{Δ}. The measurement is based on a sample of pp collision data recorded with the LHCb detector, corresponding to an integrated luminosity of 3  fb^{-1} at center-of-mass energies of 7 and 8 TeV. The measured values are S_{ϕγ}=0.43±0.30±0.11, C_{ϕγ}=0.11±0.29±0.11, and A_{ϕγ}^{Δ}=-0.67_{-0.41}^{+0.37}±0.17, where the first uncertainty is statistical and the second systematic. This is the first measurement of the observables S and C in radiative B_{s}^{0} decays. The results are consistent with the standard model predictions.

First Observation of the Radiative Decay Λ_{b}^{0}→Λγ

The radiative decay Λ_{b}^{0}→Λγ is observed for the first time using a data sample of proton-proton collisions corresponding to an integrated luminosity of 1.7  fb^{-1} collected by the LHCb experiment at a center-of-mass energy of 13 TeV. Its branching fraction is measured exploiting the B^{0}→K^{*0}γ decay as a normalization mode and is found to be B(Λ_{b}^{0}→Λγ)=(7.1±1.5±0.6±0.7)×10^{-6}, where the quoted uncertainties are statistical, systematic, and systematic from external inputs, respectively. This is the first observation of a radiative decay of a beauty baryon.

Impact of postoperative infective complications on long-term survival after liver resection for hepatocellular carcinoma

Background

Postoperative complications have a great impact on the postoperative course and oncological outcomes following major cancer surgery. Among them, infective complications play an important role. The aim of this study was to evaluate whether postoperative infective complications influence long-term survival after liver resection for hepatocellular carcinoma (HCC).

Methods

Patients who underwent resection with curative intent for HCC between July 2003 and June 2016 were identified from a multicentre database (8 institutions) and analysed retrospectively. Independent risk factors for postoperative infective complications were identified. After excluding patients who died 90 days or less after surgery, overall survival (OS) and recurrence-free survival (RFS) were compared between patients with and without postoperative infective complications within 30 days after resection.

Results

Among 2442 patients identified, 332 (13·6 per cent) had postoperative infective complications. Age over 60 years, diabetes mellitus, obesity, cirrhosis, intraoperative blood transfusion, duration of surgery exceeding 180 min and major hepatectomy were identified as independent risk factors for postoperative infective complications. Univariable analysis revealed that median OS and RFS were poorer among patients with postoperative infective complications than among patients without (54·3 versus 86·8 months, and 22·6 versus 43·2 months, respectively; both P &lt; 0·001). After adjustment for other prognostic factors, multivariable Cox regression analyses identified postoperative infective complications as independently associated with decreased OS (hazard ratio (HR) 1·20, 95 per cent c.i. 1·02 to 1·41; P = 0·027) and RFS (HR 1·19, 1·03 to 1·37; P = 0·021).

Conclusion

Postoperative infective complications decreased long-term OS and RFS in patients treated with liver resection for HCC.

[HIV-1 drug resistance and influencing factors among people living with HIV/AIDS before antiretroviral therapy in Liangshan Yi Autonomous Prefecture]

Objective: To explore HIV-1 drug resistance and influencing factors among people living with HIV/AIDS before antiretroviral therapy in Liangshan Yi Autonomous Prefecture (Liangshan). Methods: Between January 1 and June 30, in both 2017 and 2018, a cross-sectional survey was conducted in Liangshan HIV-1 pol sequences were gathered and analyzed according to WHO Guidelines on HIV drug resistance surveillance of 2014. Both HyPhy 2.2.4 and Cytoscape 3.6.1 software were used to analyze the drug resistant strains of HIV-1 transmission network. Results: A total of 464 people living with HIV/AIDS was recruited. The proportion of HIV-1 CRF07_BC subtype was 88.6% (411/464), with HIV-1 drug resistance rate was 9.9% (46/464). The HIV-1 drug resistance rates of non-nucleoside reverse transcriptase inhibitors (NNRTI), nucleoside reverse transcriptase inhibitors(NRTI) and protease inhibitors (PI) were 6.7% (31/464), 1.9% (9/464) and 0.4% (2/464) respectively. New recombinant strains of HIV-1 URF_01BC subtype was independently clustered according to the drug resistant mutation sites. Results from the multivariate logistic analysis showed that injected drug users group had higher risk on HIV-1 drug resistance (aOR=3.03, 95%CI:1.40-6.54) than heterosexual group among people living with HIV/AIDS. Conclusions: HIV-1 drug resistance rate had already been in a high level before antiretroviral therapy was in place. The newly identified recombinant strains of HIV-1 URF_01BC subtype were independently clustered according to the drug resistant mutation sites. It was necessary to strengthen the prevention of the HIV-1 drug resistant strains transmission.

[HIV genetic subtypes and comparison of the first CD(4)(+)T cell counts in newly diagnosed HIV infected patients in Liuzhou, 1998-2012]

Objective: To analyze the change trend of HIV genetic subtypes and compare the first CD(4)(+)T cell counts of newly diagnosed HIV infected patients in Liuzhou from 1998 to 2012, and provide a reference for AIDS prevention and control. Methods: Newly diagnosed HIV-infected patients from 1998 to 2012 in Liuzhou were selected through national HIV/ADIS comprehensive response information management system. Their plasma samples were used for RNA gene extraction, amplification, sequencing and genotyping. Coharan-Armitage trend test was used to analyze the ratio trend of genetic subtypes and phylogenetic clusters of HIV and Wilcoxon Rank Sum Test was used to compare the first CD(4)(+)T cell counts (CD(4)) of the different subtype HIV infected patients. Results: A total of 1 877 newly diagnosed HIV infected patients were included in the study. From 1998 to 2012, the proportions of CRF01_AE and CRF01_AE (Cluster 1) increased from 78.4% (76/97) to 91.5% (1 441/1 574), from 63.9% (62/97) to 74.0% (1 164/1 574), and the proportion of CRF07_BC decreased from 17.5% (17/97) to 4.6% (72/1 574), respectively (Z=4.632, P<0.001; Z=2.455, P=0.014; Z=-5.943, P<0.001). The median and interquartile range of the first CD(4) of the patients infected with subtype CRF01_AE (Cluster 1), CRF01_AE (Cluster 2), CRF07_BC and CRF08_BC were 230 (83-375), 215 (48-351), 365 (254-503) and 334 (206-479) cell/μl, respectively. The first CD(4) levels of the patients infected with subtype CRF01_AE (Cluster 1) or CRF01_AE (Cluster 2) were significantly lower than those of CRF07_BC (Z=-4.795, P<0.001; Z=-4.238, P<0.001). Conclusion: The genetic subtypes of HIV were mainly CRF01_AE in newly diagnosed HIV-infected patients and this subtype proportion was in increase and the first CD(4) levels of the patients were low in Liuzhou during 1998 to 2012.

Observation of an Excited B_{c}^{+} State

Using pp collision data corresponding to an integrated luminosity of 8.5  fb^{-1} recorded by the LHCb experiment at center-of-mass energies of sqrt[s]=7, 8, and 13 TeV, the observation of an excited B_{c}^{+} state in the B_{c}^{+}π^{+}π^{-} invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(B_{c}^{+})  MeV/c^{2}, where the last uncertainty is due to the limited knowledge of the B_{c}^{+} mass. It is consistent with expectations of the B_{c}^{*}(2^{3}S_{1})^{+} state reconstructed without the low-energy photon from the B_{c}^{*}(1^{3}S_{1})^{+}→B_{c}^{+}γ decay following B_{c}^{*}(2^{3}S_{1})^{+}→B_{c}^{*}(1^{3}S_{1})^{+}π^{+}π^{-}. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(B_{c}^{+})  MeV/c^{2}, and is consistent with the B_{c}(2^{1}S_{0})^{+} state. These mass measurements are the most precise to date.

Measurement of the Mass Difference Between Neutral Charm-Meson Eigenstates

We report a measurement of the mass difference between neutral charm-meson eigenstates using a novel approach that enhances sensitivity to this parameter. We use 2.3×10^{6} D^{0}→K_{S}^{0}π^{+}π^{-} decays reconstructed in proton-proton collisions collected by the LHCb experiment in 2011 and 2012. Allowing for CP violation in mixing and in the interference between mixing and decay, we measure the CP-averaged normalized mass difference x_{CP}=[2.7±1.6(stat)±0.4(syst)]×10^{-3} and the CP-violating parameter Δx=[-0.53±0.70(stat)±0.22(syst)]×10^{-3}. The results are consistent with CP symmetry. These determinations are the most precise from a single experiment and, combined with current world-average results, yield the first evidence that the masses of the neutral charm-meson eigenstates differ.

Observation of a Narrow Pentaquark State, P_{c}(4312)^{+}, and of the Two-Peak Structure of the P_{c}(4450)^{+}

A narrow pentaquark state, P_{c}(4312)^{+}, decaying to J/ψp, is discovered with a statistical significance of 7.3σ in a data sample of Λ_{b}^{0}→J/ψpK^{-} decays, which is an order of magnitude larger than that previously analyzed by the LHCb Collaboration. The P_{c}(4450)^{+} pentaquark structure formerly reported by LHCb is confirmed and observed to consist of two narrow overlapping peaks, P_{c}(4440)^{+} and P_{c}(4457)^{+}, where the statistical significance of this two-peak interpretation is 5.4σ. The proximity of the Σ_{c}^{+}D[over ¯]^{0} and Σ_{c}^{+}D[over ¯]^{*0} thresholds to the observed narrow peaks suggests that they play an important role in the dynamics of these states.

Observation of CP Violation in Charm Decays

A search for charge-parity (CP) violation in D^{0}→K^{-}K^{+} and D^{0}→π^{-}π^{+} decays is reported, using pp collision data corresponding to an integrated luminosity of 5.9  fb^{-1} collected at a center-of-mass energy of 13 TeV with the LHCb detector. The flavor of the charm meson is inferred from the charge of the pion in D^{*}(2010)^{+}→D^{0}π^{+} decays or from the charge of the muon in B[over ¯]→D^{0}μ^{-}ν[over ¯]_{μ}X decays. The difference between the CP asymmetries in D^{0}→K^{-}K^{+} and D^{0}→π^{-}π^{+} decays is measured to be ΔA_{CP}=[-18.2±3.2(stat)±0.9(syst)]×10^{-4} for π-tagged and ΔA_{CP}=[-9±8(stat)±5(syst)]×10^{-4} for μ-tagged D^{0} mesons. Combining these with previous LHCb results leads to ΔA_{CP}=(-15.4±2.9)×10^{-4}, where the uncertainty includes both statistical and systematic contributions. The measured value differs from zero by more than 5 standard deviations. This is the first observation of CP violation in the decay of charm hadrons.

Search for CP Violation in D_{s}^{+}→K_{S}^{0}π^{+}, D^{+}→K_{S}^{0}K^{+}, and D^{+}→ϕπ^{+} Decays

A search for charge-parity (CP) violation in Cabibbo-suppressed D_{s}^{+}→K_{S}^{0}π^{+}, D^{+}→K_{S}^{0}K^{+}, and D^{+}→ϕπ^{+} decays is reported using proton-proton collision data, corresponding to an integrated luminosity of 3.8  fb^{-1}, collected at a center-of-mass energy of 13 TeV with the LHCb detector. High-yield samples of kinematically and topologically similar Cabibbo-favored D_{(s)}^{+} decays are analyzed to subtract nuisance asymmetries due to production and detection effects, including those induced by CP violation in the neutral kaon system. The results areA_{CP}(D_{s}^{+}→K_{S}^{0}π^{+})=(1.3±1.9±0.5)×10^{-3},A_{CP}(D^{+}→K_{S}^{0}K^{+})=(-0.09±0.65±0.48)×10^{-3},A_{CP}(D^{+}→ϕπ^{+})=(0.05±0.42±0.29)×10^{-3},where the first uncertainties are statistical and the second systematic. They are the most precise measurements of these quantities to date, and are consistent with CP symmetry. A combination with previous LHCb measurements, based on data collected at 7 and 8 TeV, is also reported.

Search for Lepton-Universality Violation in B^{+}→K^{+}ℓ^{+}ℓ^{-} Decays

A measurement of the ratio of branching fractions of the decays B^{+}→K^{+}μ^{+}μ^{-} and B^{+}→K^{+}e^{+}e^{-} is presented. The proton-proton collision data used correspond to an integrated luminosity of 5.0  fb^{-1} recorded with the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV. For the dilepton mass-squared range 1.1<q^{2}<6.0  GeV^{2}/c^{4} the ratio of branching fractions is measured to be R_{K}=0.846_{-0.054}^{+0.060}_{-0.014}^{+0.016}, where the first uncertainty is statistical and the second systematic. This is the most precise measurement of R_{K} to date and is compatible with the standard model at the level of 2.5 standard deviations.

[Study on the relationship between HIV drug resistance and CD4(+)T cell counts among antiretroviral therapy patients with low viral load]

Objective: To explore drug resistance of different viral loads, and investigate the relationship between drug resistance and CD4(+)T cell counts in patients with HIV antiretroviral therapy (ART) in China from 2003 to 2015. Methods: Data were extracted from the Chinese National HIVDR Surveillance database from 2003 to 2015. For this study, the data collected were as follows: having received ART for ≥12 months; 18 years or older; demographic characteristics, information of ART, CD4(+)T cell counts, viral load (VL) and HIV drug resistance of a total of 8 362 patients were collected. Multi-variables non-conditional logistic regression model was used to study the relationship between viral load, HIV drug resistance and CD4(+)T cell counts. Results: Participants with age of (41.8±10.5) years were enrolled in this study. Among them, 59.9% (5 009 cases) were men. The percentage of CD4(+)T cell counts <200 cells/μl in the total population was 17.9% (1 496 cases), the highest was in VL ≥1 000 copies/ml with drug resistance, which was 43.0% (397/923) , followed by VL 50-999 copies/ml with drug resistance, which was 31.1% (69/222), and the lowest was in VL 50-999 copies/ml without drug resistance 13.2% (273/2 068). Compared to VL 50-999 copies/ml without drug resistance, VL<50 copies/ml, VL 50-999 with drug resistance, VL≥1 000 copies/ml without drug resistance, and VL ≥1 000 copies/ml with drug resistance, the OR (95%CI) of CD4 <200 cells/μl were 0.9 (0.7-1.0), 3.2 (2.3-4.4), 2.6 (2.1-3.2), and 4.9 (4.0-5.9), respectively. Among 222 patients with VL 50-999 and HIVDR, the most frequent antiretroviral drugs were EFV and NVP, both of which were NNRTI, and whose percentage both were 94.1% (209 cases). The most frequent mutations were M184V/I (NNRTI), and the percentage was 26.1% (58 cases). The second one was K103N (NNRTI), and the percentage was 22.5% (50 cases). The percentage of V32L/E (PI) and V82A (PI) were lower, they were 0.9% (2 cases) and 0.5% (1 case) respectively. Conclusion: Decreased CD4(+)T cell counts were associated with HIV drug resistance at low viraemia. In the case of low viral load, the most vulnerable were the NNRTI antiviral drugs such as EFV and NVP.

[HIV-1 drug resistance transmission threshold survey in Dehong prefecture of Yunnan province, 2015]

Objective: To study the HIV-1 drug resistance transmission level in HIV infected persons receiving no antiviral therapy in Dehong prefecture of Yunnan province in 2015. Methods: A total of 72 plasma samples were collected from recently reported HIV-infected persons aged 16-25 years in Dehong from January to July 2015 for drug resistance gene detection. Results: Forty eight samples were successfully sequenced and analyzed. Among them, 31.2% (15/48) were from Chinese, and 68.8% (33/48) were from Burmese. Based on pol sequences, HIV genotypes included URF (52.08%, 25/48), CRF01_AE (16.67%, 8/48), RF07_BC (10.42%, 5/48), subtype B (6.25%, 3/48), subtype C (6.25%, 3/48), CRF57_BC (6.25%, 3/48) and CRF08_BC (2.08%, 1/48). One drug resistant mutation site to non-nucleoside analog reverse transcriptase inhibitor (NNRTI) and two drug resistant mutation site to nucleoside analog reverse transcriptase inhibitor (NRTI) were detected in four sequences. Based on the statistical method of HIV drug resistance threshold survey, the prevalence of HIV-1 drug resistant strain was 5%-15%. Conclusions: The proportion of Burmese among newly reported HIV-infected individuals aged 16-25 years in Dehong in 2015 was higher. HIV-1 genetic diversity was found in Dehong. The prevalence of HIV-1 drug resistant strain had reached a moderate level in Dehong.

[The association between the characteristics of egocentric network and HIV prevalence among men who have sex with men]

Objective: This study aimed to analyze the association between the characteristics of egocentric network and HIV prevalence among men who have sex with men (MSM) through social network analysis. Methods: The study was conducted in Guangzhou city from November 2016 to June 2017 using convenient sampling method. Participants were recruited from 13 voluntary counseling and testing (VCT) locations. Data were collected by using nomination generation and nomination interpretation methods. Questionnaire includes two parts, the first part about the social tie, and the second one about social demography and behavioral characteristics of respondents and their nominees. The multivariate logistic regression was applied to quantify the association. Results: 8.67%(93/1 073) HIV antibody positive MSM had been detected in 1 073 respondents who nominated 4 301 partners in total. Compared to egocentric sexual network with a size of 1-2, the size of sexual network larger than 3 (OR=1.68, 95%CI: 1.07-2.65) were associated with HIV infection. Compared to egocentric risk sexual network with a size of 1-2, the size of risk sexual networks larger than 3 (OR=1.87, 95%CI: 1.06-3.31) were associated with HIV infection. There were no significant association between marital similarity of respondents and their nominees, the type of the relationship of sexual partners and HIV prevalence (P>0.05). Conclusion: The composition of social network in MSM is related to their susceptibility of HIV infection. MSM population with a large sexual network is more susceptible to HIV infection.

Multicentre study of the prognostic impact of preoperative bodyweight on long-term prognosis of hepatocellular carcinoma

BACKGROUND

Whether preoperative bodyweight is associated with long-term prognosis in patients after liver resection for hepatocellular carcinoma (HCC) is controversial. This study aimed to investigate the relationship of patient weight with long-term recurrence and overall survival (OS) after curative liver resection for HCC.

METHODS

Data for patients with HCC who underwent curative liver resection between 2000 and 2015 in five centres in China were analysed retrospectively in three groups according to their preoperative BMI: underweight (BMI 18·4 kg/m² or less), normal weight (BMI 18·5-24·9 kg/m² ) and overweight (BMI 25·0 kg/m² or above). Patients' baseline characteristics, operative variables and long-term survival outcomes were compared. Univariable and multivariable Cox regression analyses were performed to identify risk factors for OS and recurrence-free survival (RFS) after resection.

RESULTS

Of 1524 patients, 107 (7·0 per cent) were underweight, 891 (58·5 per cent) were of normal weight and 526 (34·5 per cent) were overweight. Univariable analyses showed that underweight and overweight patients had poorer OS (both P < 0·001) and RFS (both P < 0·001) than patients of normal weight. Multivariable Cox regression analysis also identified both underweight and overweight to be independent risk factors for OS (hazard ratio (HR) 1·22, 95 per cent c.i. 1·19 to 1·56, P = 0·019; and HR 1·57, 1·36 to 1·81, P < 0·001, respectively) and RFS (HR 1·28, 1·16 to 1·53, P = 0·028; and HR 1·34, 1·17 to 1·54, P < 0·001).

CONCLUSION

Underweight and overweight patients appear to have a worse prognosis than those of normal weight following liver resection for HCC.