RNA-Seq analysis of long non-coding RNA in human intestinal epithelial cells infected by Shiga toxin-producing Escherichia coli.

BACKGROUND: The Shiga toxin-producing Escherichia coli (STEC) infects animals and induces acute intestinal inflammation. Long non-coding RNAs (lncRNAs) are known to play crucial roles in modulating inflammation response. However, it is not clear whether lncRNAs are involved in STEC-induced inflammation. METHODS AND RESULTS: To understand the association of lncRNAs with STEC infection, we used RNA-seq technology to analyze the profiles of lncRNAs in Mock-infected and STEC-infected human intestinal epithelial cells (HIECs). We detected a total of 702 lncRNAs differentially expressed by STEC infection. 583 differentially expressed lncRNAs acted as competitive microRNAs (miRNAs) binding elements in regulating the gene expression involved in TNF signaling pathway, IL-17 signaling pathway, PI3K-Akt signaling pathway, and apoptosis pathways. We analyzed 3 targeted genes, TRADD, TRAF1 and TGFB2, which were differentially regulated by mRNA-miRNA-lncRNA interaction network, potentially involved in the inflammatory and apoptotic response to STEC infection. Functional analysis of up/downstream genes associated with differentially expressed lncRNAs revealed their role in adheres junction and endocytosis. We also used the qRT-PCR technique to validate 8 randomly selected differentially expressed lncRNAs and mRNAs in STEC-infected HIECs. CONCLUSION: Our results, for the first time, revealed differentially expressed lncRNAs induced by STEC infection of HIECs. The results will help investigate the molecular mechanisms for the inflammatory responses induced by STEC.

α-Conotoxin recombinant protein ImI-AFP3 efficiently inhibits the growth and migration of lung cancer cells.

α-Conotoxin ImI is a selective antagonist of alpha7 nicotinic acetylcholine receptor (α7 nAChR) that is involved in cancer development. Human alpha fetoprotein domain 3 (AFP3) is a prototype of anticancer agents. In an effort to design drugs for anticancer treatments, we fused the ImI peptide to AFP3 as a fusion protein for testing. The fusion protein (ImI-AFP3) was highly expressed in the insect Bac-to-Bac system. The purified fusion protein was found to have improved anticancer activity and synergized with the drug gefitinib to inhibit the growth and migration of A549 and NCI-H1299 lung cancer cells. Our data have demonstrated that the recombinant protein ImI-AFP3 is a promising candidate for drug development to suppress lung cancer cell growth, especially to suppress hepatoid adenocarcinoma of the lung (HAL) cell growth.

NRG2 family members of Arabidopsis and maize regulate nitrate signalling and promote nitrogen use efficiency.

Nitrogen (N) is an essential nutrient for plant growth, and most plants absorb it as nitrate. AtNRG2 has been reported to play an important role in nitrate regulation. In this study, we investigated the functions of AtNRG2 family members of Arabidopsis thaliana and maize in nitrate signalling and metabolism. Our results showed that both AtNRG2.10 and AtNRG2.15 regulated nitrate signalling and metabolism. Overexpression of AtNRG2.11 (AtNRG2) could promote plant growth and improve nitrogen use efficiency (NUE). In addition, the maize genome harbors 23 ZmNRG2 members. We detected the expression of these genes treated with nitrate and the expression of four genes was strongly induced with ZmNRG2.7 having the highest levels. Overexpression of ZmNRG2.7 in the atnrg2 mutant could restore the defects of atnrg2, suggesting that ZmNRG2.7 is involved in nitrate signalling and metabolism. Moreover, the overexpression lines of ZmNRG2.7 showed increased biomass and NUE. These findings demonstrate that at least a part of NRG2 family genes in Arabidopsis and maize regulate nitrate signalling and provide a molecular basis for improving the NUE of crops.

Integrated Wearable System for Monitoring Skeletal Muscle Force of Lower Extremities.

Continuous monitoring of lower extremity muscles is necessary, as the muscles support many human daily activities, such as maintaining balance, standing, walking, running, and jumping. However, conventional electromyography and physiological cross-sectional area methods inherently encounter obstacles when acquiring precise and real-time data pertaining to human bodies, with a notable lack of consideration for user comfort. Benefitting from the fast development of various fabric-based sensors, this paper addresses these current issues by designing an integrated smart compression stocking system, which includes compression garments, fabric-embedded capacitive pressure sensors, an edge control unit, a user mobile application, and cloud backend. The pipeline architecture design and component selection are discussed in detail to illustrate a comprehensive user-centered STIMES design. Twelve healthy young individuals were recruited for clinical experiments to perform maximum voluntary isometric ankle plantarflexion contractions. All data were simultaneously collected through the integrated smart compression stocking system and a muscle force measurement system (Humac NORM, software version HUMAC2015). The obtained correlation coefficients above 0.92 indicated high linear relationships between the muscle torque and the proposed system readout. Two-way ANOVA analysis further stressed that different ankle angles (p = 0.055) had more important effects on the results than different subjects (p = 0.290). Hence, the integrated smart compression stocking system can be used to monitor the muscle force of the lower extremities in isometric mode.

Cooperative Motion Optimization Based on Risk Degree under Automatic Driving Environment.

Appropriate traffic cooperation at intersections plays a crucial part in modern intelligent transportation systems. To enhance traffic efficiency at intersections, this paper establishes a cooperative motion optimization strategy that adjusts the trajectories of autonomous vehicles (AVs) based on risk degree. Initially, AVs are presumed to select any exit lanes, thereby optimizing spatial resources. Trajectories are generated for each possible lane. Subsequently, a motion optimization algorithm predicated on risk degree is introduced, which takes into account the trajectories and motion states of AVs. The risk degree serves to prevent collisions between conflicting AVs. A cooperative motion optimization strategy is then formulated, incorporating car-following behavior, traffic signals, and conflict resolution as constraints. Specifically, the movement of all vehicles at the intersection is modified to achieve safer and more efficient traffic flow. The strategy is validated through a simulation using SUMO. The results indicate a 20.51% and 11.59% improvement in traffic efficiency in two typical scenarios when compared to a First-Come-First-Serve approach. Moreover, numerical experiments reveal significant enhancements in the stability of optimized AV acceleration.

Potential source and health risks of black carbon based on MERRA-2 reanalysis data in a typical industrial city of North China Plain.

Black carbon (BC) significantly affects climate, environmental quality, and human health. This study utilised Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), which can compensate for the shortcomings of ground BC monitoring in spatial-temporal distribution to study the pollution characteristics of BC and potential pollution sources in a typical industrial city (Xinxiang) with serious air pollution in northern China. The results showed that average daily ground observation and MERRA-2 concentration of BC of 7.33 µg m-3 and 9.52 µg m-3. The mean BC concentration derived from MERRA-2 reanalysis data was higher than ground measurement due to resolution limitations and pollution from the northern regions. The reliability of the MERRA-2 data was confirmed through correlation analysis. Consideration of the spatial distribution of BC from MERRA-2 and incorporating the potential source contribution function (PSCF), concentration-weighted trajectory (CWT), and emission inventory, other possible source areas and primary sources of BC in Xinxiang were investigated. The results indicated that implementing transportation and residential emission control measures in Henan Province and its surrounding provinces, such as Hebei Province, will effectively decrease the BC level in Xinxiang City. A passively smoked cigarettes model was used to evaluate the risk of BC exposure. The percentage of lung function decrement (PLFD) was the highest in school-age children, while the impact on lung cancer (LC) health risk was comparatively lower. Notably, the BC health risk in Xinxiang was lower than in most cities across Asia.

The effectiveness of health education based on the 5Ts for teach-back on oral nutritional supplements compliance of post-discharge patients after surgery for gastric cancer: a randomized controlled trial.

OBJECTIVE: This study aims to explore the 5Ts teach-back(5Ts) to improve oral nutritional supplements (ONS) compliance of discharged patients after gastric cancer surgery. SETTING AND METHODS: Patients were recruited from the Bethune First Hospital of Jilin University. The patients were randomly assigned to 5Ts (n = 54) and routine health education (n = 54). Weekly ONS compliance was collected by "weekly ONS diary." ONS knowledge, health literacy, and health education satisfaction were collected at baseline and 5 weeks after discharge. Chi-square test, Mann-Whitney U test, and T test were used for data analysis. RESULTS: At the end of the intervention, there were 41 and 40 patients in intervention and control group. 5Ts significantly improve ONS compliance, ONS knowledge level (P = 0.000), health literacy level (P = 0.011), and health education satisfaction (P = 0.009) of patients. At the end of follow-up, there were 30 and 27 patients in two groups, and no significant difference in ONS compliance (P = 0.728). CONCLUSION: The 5Ts can significantly improve patients' ONS compliance and the effect of health education. TRIAL REGISTRATION NUMBER: This prospective trial was registered in the Chinese Clinical Trial Registry at ChiCTR2000040986 ( http://www.chictr.org.cn ). PATIENT OR PUBLIC CONTRIBUTION: Jia Wang and Haiyan Hu contributed to the performance of the study, analysis and interpretation the data, and drafted the manuscript; Jianan Sun and Qing Zhang contributed to the supervision of the study and interpreted the data; Zhiming Chen contributed to the analysis and interpretation the data; Qiuchen Wang contributed to the performance of the study and revised the manuscript; Mingyue Zhu contributed to interpretation the data; Jiannan Yao contributed to revise the manuscript; Hua Yuan and Xiuying Zhang contributed to the conception of the study, performed the study, interpreted the data, and significantly revised the manuscript. All authors screened the final version of the manuscript.

A novel approach of intraoperative cholangiography in laparoscopic left lateral sectionectomy in living donor liver transplantation.

BACKGROUND: Accurate division of bile duct during laparoscopic donor hepatectomy in living donor liver transplantation is essential. We here present a novel approach to achieve cholangiography via the bile duct stump of segment IV (B4 stump) during laparoscopic donor hepatectomy in adult-to-pediatric living donor liver transplantation. PATIENTS AND METHODS: Donors who underwent laparoscopic left lateral sectionectomy (LLLS) from January 2022 to April 2022 in our liver transplant center were retrospectively analyzed. A total of 32 donors were eventually enrolled into this study. Cholangiography via the B4 stump was performed in 11 donors (B4 group) while indocyanine green (ICG) fluorescence guiding was performed in 21 donors (ICG group). Perioperative data were collected and compared between groups. RESULTS: Cholangiography by catheterizing the B4 stump was successfully performed in all 11 donors in the B4 group. The mean time of this procedure was 12.82 ± 9.11 min. Compared to the ICG group, it was more likely to acquire single bile duct orifice on graft in the B4 group (B4: 10/11, 90.91% vs ICG: 9/21, 42.86%) and it was significantly different (p = 0.030). The donors' complications (Clavien-Dindo grade III-IV) were not significantly different. There was one donor developed intraperitoneal effusion in B4 group, while two donors (one bile leakage and one biliary stricture) developed biliary tract related complications in the ICG group. A Roux-en-Y was performed to solve the biliary stricture in the ICG group. The recipients' outcomes were not significantly different between groups. CONCLUSIONS: Cholangiography via the B4 stump catheterization is feasible and safe in identifying the bifurcation of bile duct during LLLS.

Design and Performance Evaluation of a Novel Automatic Stapling Device for Knotless Barbed Suture in Laparoscopic Surgery.

NEED: This study developed a novel automatic stapling device for improving the speed and stability of suturing in laparoscopic surgery. TECHNICAL SOLUTION: The stapling device included 3 components: driver module, actuator module, and transmission module. PROOF OF CONCEPT: A negative water leakage test of the in vitro intestinal defect model preliminarily demonstrated the safety of the new automatic stapling device. The suturing time for skin and peritoneal defects through the automatic stapling device was significantly shorter than that through the ordinary needle-holder suture (P < .05). These 2 suture methods had good tissue alignment. The automatic suture showed less inflammatory cell infiltration and lower inflammatory response scores at the tissue incision on days 3 and 7 after surgery compared with the ordinary needle-holder suture, with statistically significant differences (P < .05). NEXT STEPS: In the future, the device needs to be further optimized and the experimental needs to be supplemented to provide some evidence for clinical use. CONCLUSION: This novel automatic stapling device for knotless barbed suture designed in this study has advantages of shorter suturing time and milder inflammatory responses than the ordinary needle-holder suture, safe and feasible in laparoscopic surgery.

Association between self-perception of aging and cognitive function in Chinese older adults: The mediation effect of health behaviors.

OBJECTIVE: To investigate the association between self-perception of aging (SPA) and cognitive function in Chinese older adults, and to explore the mediating role of health behaviors. METHODS: This study included 5,445 Chinese older adults from the 2018 wave of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). Correlation, linear regression and mediation effect analysis were employed to evaluate the association. RESULTS: SPA is significantly related to the health behaviors (r = 0.160, P < 0.01) and cognition (r = 0.086, P < 0.01), and health behaviors exhibited a positive correlation with cognition (r = 0.179, P < 0.01). SPA and health behaviors significantly impacted cognition (ß = 0.032, P = 010; ß = 0.103, P < 0.001). Health behaviors partially mediated the effect of SPA on cognitive function, accounting for 27.12 % of the total effect. CONCLUSION: Health behaviors mediate the association between SPA and cognitive function. Healthcare providers should prioritize addressing SPA of older adults and encourage them to engage in health behaviors for cognitive health.

α-Fetoprotein fragment synergizes with sorafenib to inhibit hepatoma cell growth and migration and promote the apoptosis.

Alpha fetoprotein (AFP) is associated with hepatocellular carcinoma (HCC) by stimulating the proliferation, metastasis and drug resistance. The application of AFP fragments to inhibit the malignant behaviours induced by AFP is a new strategy for the treatment of HCC. In an effort to design, screen and discover drugs, we attempted to express different human AFP fragments (AFP220-609 , AFP390-609 and AFP460-609 ) in a Bac-to-Bac system. We found that the AFP390-609 fragment was highly expressed in the system. Then, we assessed the bioactivity of the fragment in the human liver cancer cell line Bel7402, and the results indicated that the AFP fragment synergized with sorafenib to inhibit the hepatoma cell growth and migration and promote the apoptosis. This study provides a method to produce significant AFP fragments to screen AFP inhibitors for use in HCC therapy.

Endoplasmic Reticulum-Targeting Near-Infrared Fluorescent Probe for CYP2J2 Activity and Its Imaging Application in Endoplasmic Reticulum Stress and Tumor.

CYP2J2 as an endoplasmic reticulum (ER)-expressed vital cytochrome P450 isoform participates in the metabolism of endogenous polyunsaturated fatty acids. Its abnormal expression and function are closely related to the progress of cancer and cardiovascular diseases. Herein, an ER-targeting near-infrared (NIR) fluorescent probe ER-BnXPI was developed for monitoring CYP2J2 activity, which possessed a high selectivity and sensitivity toward CYP2J2 among various CYP450 isoforms and exhibited excellent subcellular localization for ER. Then, the CYP2J2 variation behavior under the ER stress model was imaged by ER-BnXPI in living cells and successfully used for the in vivo imaging in different tumors that well distinguished tumor tissues from para-cancerous tissues. All these findings fully demonstrated that ER-BnXPI could be used as a promising tool for exploring the physiological function of CYP2J2 and provided some novel approach for the diagnosis and therapy of CYP2J2-related vascular inflammation and cancer.

Camrelizumab combined with apatinib and S-1 as second-line treatment for patients with advanced gastric or gastroesophageal junction adenocarcinoma: a phase 2, single-arm, prospective study.

BACKGROUND: The current second-line treatment of advanced gastric or gastroesophageal junction adenocarcinoma remains unsatisfactory. Anti-PD-1 monoclonal antibody combined with anti-angiogenic therapy shows anti-tumor activity and synergistic effect. We aimed to assess the efficacy and safety of the combination therapy of camrelizumab, apatinib, and S-1 in patients with gastric or gastroesophageal junction adenocarcinoma. METHODS: In this open-label, single-arm, phase 2 trial, in each 21-day cycle, eligible patients received 200 mg intravenous camrelizumab in the first day, 500 mg oral apatinib once daily continuously, and specific dose oral S-1 in the first 14 days until the trial was discontinued disease progression, development of intolerable toxicity, or withdrawal of consent. The primary endpoint was objective response rate. The secondary endpoints were disease control rate, progression-free survival and overall survival, and safety. This study was registered at ClinicalTrials.gov, NCT04345783. RESULTS: Between May 2019 and August 2020, we enrolled a total of 24 patients in this trial. At the data cutoff (December 1, 2020), the median follow-up duration was 8.13 months. Seven of 24 (29.2%, 95%CI 14.9-49.2%) patients reached objective response. The median-progression-free survival was 6.5 months (95%CI 6.01-6.99) and the median overall survival was not reached. Grade 3 or 4 adverse events occurred in 6 (25.0%) patients, including elevated transaminase, thrombocytopenia, fatigue, proteinuria, and intestinal obstruction. No serious treatment-related adverse events or treatment-related deaths occurred. CONCLUSIONS: In this trial, the combination of camrelizumab, apatinib, and S-1 showed promising anti-tumor activity and manageable toxicity as a second-line therapy in patients with advanced gastric or gastroesophageal junction adenocarcinoma, regardless of PD-L1 expression. CLINICAL TRIAL REGISTRATION: NCT04345783.

Preferences for oral nutritional supplement therapy among postoperative patients with gastric cancer: a discrete choice experiment.

PURPOSES: Patients after gastrectomy have poor compliance with oral nutritional supplement (ONS) therapy. Incorporating patient preferences into treatment decisions allows possible product improvements or treatment focus adjustments. The purpose of this research was to investigate the preferences for ONS therapy among postoperative patients with gastric cancer, and to provide person-centered oral nutrition management strategies. METHODS: A discrete choice experiment was designed and implemented within a Chinese cancer population. The survey was administered via paper-based questionnaires during face-to-face interviews with assistance from health professionals. A mixed logit model was used to estimate respondents' preferences for different levels of nutrition therapy attributes. RESULTS: One hundred ninety respondents valued "Adverse reactions-almost none" (ß 3.43 [SE, 0.28]) the most, followed by "Flavor-good taste" (ß 0.68 [SE, 0.13]) and "Follow-up frequency-once every 2 weeks" (ß 0.52 [SE, 0.13]), and were willing to pay more for these attribute levels. Respondents would be 93.73% more likely to accept a nutrition therapy program if there were almost no adverse reactions compared to the frequent adverse reactions. CONCLUSIONS: Health professionals should pay attention to the management and prevention of adverse reactions when prescribing nutritional products, and provide diversified ONS products when necessary to meet patient preferences. When formulating intervention strategies, health professionals should also consider the different characteristics of patients, acknowledge the importance of the role of nurse specialists in a novel model of multidisciplinary nutritional care, standardize ONS information, follow up regularly, and encourage patients' families to participate in daily nutrition care.

Factors influencing adherence to healthy eating behaviors among adult colorectal cancer survivors: a systematic mixed method review.

PURPOSE: Under the umbrella of social cognitive theory, we examined the influences of personal, environmental, and behavioral factors on adherence to healthy eating behaviors among colorectal cancer survivors. METHODS: Based on Pluye and Hong's framework, a systematic mixed studies review was conducted. An extensive search strategy was applied in PubMed, Web of Science, Embase, CINAHL, and PsycINFO (from date of record to 2022 January 22). The pillar integration process was employed to integrate the extracted data. The Mixed Methods Appraisal Tool was used to appraise the quality of all retained studies. RESULTS: Twenty-eight studies with a total sample size of 5106 were included in the analysis, with 15 quantitative studies, 12 qualitative studies, and 1 mixed method study. The critical appraisal showed that 22 of the 28 studies (79%) were rated with five stars, while 6 (21%) were rated with four stars. The personal factors influencing adherence to healthy eating behaviors among colorectal cancer survivors included outcome expectancies, self-efficacy, psychological factors, knowledge about healthy eating, demographic and disease characteristics, environmental factors incorporated outside information on healthy eating, power of surrounding people, social activities, cultural milieus, socioeconomic status, and education. The behavioral factors included self-regulation of diet, goals, and other behaviors closely related to healthy eating behaviors. CONCLUSIONS: Adherence to healthy eating behaviors among colorectal cancer survivors was influenced collectively by personal factors, environmental factors and behavioral factors.

The unconventional prefoldin RPB5 interactor mediates the gravitropic response by modulating cytoskeleton organization and auxin transport in Arabidopsis.

Gravity-induced root curvature involves the asymmetric distribution of the phytohormone auxin. This response depends on the concerted activities of the auxin transporters such as PIN-FORMED (PIN) proteins for auxin efflux and AUXIN RESISTANT 1 (AUX1) for auxin influx. However, how the auxin gradient is established remains elusive. Here we identified a new mutant with a short root, strong auxin distribution in the lateral root cap and an impaired gravitropic response. The causal gene encoded an Arabidopsis homolog of the human unconventional prefoldin RPB5 interactor (URI). AtURI interacted with prefoldin 2 (PFD2) and PFD6, two ß-type PFD members that modulate actin and tubulin patterning in roots. The auxin reporter DR5rev :GFP showed that asymmetric auxin redistribution after gravistimulation is disordered in aturi-1 root tips. Treatment with the endomembrane protein trafficking inhibitor brefeldin A indicated that recycling of the auxin transporter PIN2 is disrupted in aturi-1 roots as well as in pfd mutants. We propose that AtURI cooperates with PFDs to recycle PIN2 and modulate auxin distribution.

CDC48B facilitates the intercellular trafficking of SHORT-ROOT during radial patterning in roots.

CELL DIVISION CONTROL PROTEIN48 (CDC48) is essential for membrane fusion, protein degradation, and other cellular processes. Here, we revealed the crucial role of CDC48B in regulating periclinal cell division in roots by analyzing the recessive gen1 mutant. We identified the GEN1 gene through map-based cloning and verified that GEN1 encodes CDC48B. gen1 showed severely inhibited root growth, increased periclinal cell division in the endodermis, defective middle cortex (MC) formation, and altered ground tissue patterning in roots. Consistent with these phenotypes, CYCLIND 6;1(CYCD6;1), a periclinal cell division marker, was upregulated in gen1 compared to Col-0. The ratio of SHRpro :SHR-GFP fluorescence in pre-dividing nuclei versus the adjacent stele decreased by 33% in gen1, indicating that the trafficking of SHORT-ROOT (SHR) decreased in gen1 when endodermal cells started to divide. These findings suggest that the loss of function of CDC48B inhibits the intercellular trafficking of SHR from the stele to the endodermis, thereby decreasing SHR accumulation in the endodermis. These findings shed light on the crucial role of CDC48B in regulating periclinal cell division in roots.

Prevalence, Antimicrobial Resistance, and Molecular Characterization of Staphylococcus aureus Isolated from Animals, Meats, and Market Environments in Xinjiang, China.

Staphylococcus aureus has been recognized as an important foodborne pathogen. However, knowledge about the epidemiology and genetic characteristics of S. aureus in the meat production chain from farm to market is limited. The aim of this study was to investigate the genetic characteristics of S. aureus in animal samples isolated from Xinjiang province farms and farmer' markets, by determining staphylococcal protein A (spa) repeat region and virulence factor typing, and by assessment of antimicrobial resistance. Out of 1324 samples, 128 (9.7%) were positive for S. aureus, 26 (2.0%) of them were identified as methicillin-resistant S. aureus (MRSA) and 88 (6.6%) of them were identified as vancomycin-resistant S. aureus (VRSA). Antimicrobial resistance was determined using the disk diffusion method. S. aureus isolates showed resistance to penicillin G (98.4%), clarithromycin (69.5%), erythromycin (69.5%), vancomycin (68.8%), and tetracycline (67.2%). A total of 80.4% of isolates showed resistance to three or more antimicrobial classes. PCR was used to detect ten virulence genes such as the enterotoxin (sea, seb, and sec), hemolysin (hla and hlb), clumping factor (clfA), and fibronectin-binding proteins A and B (fnbA and fnbB). Our study showed that isolates harbored two or seven virulence genes. All strains encode hla and clfA, and half of them encode hlb and enterotoxin genes. The spa typing results showed that the 128 isolates were grouped into 32 spa types. The main spa types were t127 (22.7%), t2592 (12.5%), t437 (10.9%), and t2616 (10.9%). Notably, isolates of t437 type accounted for 46.2% of the MRSA. Our data indicate that meats in the slaughterhouse and farmers' markets were contaminated with S. aureus. S. aureus virulence genes and spa types were diverse, and its antibiotic resistance was serious. The presence of MRSA and VRSA represents potential public health risks and warrants further investigation regarding the driving factors of such resistance and their transmission to humans.

Asymmetric direct detection of orthogonal offset carriers assisted polarization multiplexed single-sideband signals.

We propose and demonstrate the asymmetric direct detection (ADD) of polarization division multiplexed single-sideband (PDM-SSB) signals with orthogonal offset carriers. ADD exploits the photocurrent difference to eliminate the Y-Pol interference in the X-Pol, and the X-Pol signal intensity to eliminate the X-Pol interference in the Y-Pol without resorting to iterative algorithms. This enables not only low-complexity signal linearization but also a simplified receiver front-end composed of a single optical filter, two single-ended photodiodes and two analog-to-digital converters (ADC). In the experiment, we first perform a parametric study of the proposed scheme at 40 Gbaud in the back-to-back configuration (B2B) to evaluate the performance impact of different system parameters including the carrier to signal power ratio (CSPR), the matched filter roll-off, and the filter guard band. Next, we demonstrate the transmission of 416 Gbit/s PDM 16-QAM signal over 80 km single-mode fiber (SMF) below the soft-decision forward error correction (SD-FEC) threshold of 2×10-2. We also numerically study the effectiveness of a 2×2 multiple-input-multiple-output MIMO equalizer in alleviating the inter-polarization linear crosstalk resulting from the non-orthogonal PDM-SSB signals due to polarization-dependent loss (PDL), which is not negligible for potential on-chip implementation of ADD.

Asymmetric direct detection of twin-SSB signals.

We propose the asymmetric direct detection (ADD) of twin-single sideband (SSB) signals based on a simple receiver front-end composed of one optical filter and two photodiodes. ADD exploits the photocurrent difference between a filtered and unfiltered signal pair to reconstruct and linearize the received twin-SSB signal with a high electrical spectral efficiency (ESE). We evaluate the performance impact of the critical system parameters on ADD and demonstrate 231 Gb/s net rate 16-QAM twin-SSB transmission with 6.03 b/s/Hz ESE over an 80 km standard single-mode fiber below the ${1} \times {{10}^{ - 2}}$1×10-2 hard-decision forward error correction threshold. We also found that the bit error rate performance of ADD is robust against the relative center wavelength drifting of the optical filter.