Effect of the bonding layer and multigrading layers on the performance of a wafer-bonded InGaAs/Si single-photon detector.

A wafer-bonded InGaAs/Si avalanche photodiode (APD) at a wavelength of 1550 nm was theoretically simulated. We focused on the effect of the I n 1-x G a x A s multigrading layers and bonding layers on the electric fields, electron and hole concentrations, recombination rates, and energy bands. In this work, I n 1-x G a x A s multigrading layers inserted between Si and InGaAs were adopted to reduce the discontinuity of the conduction band between Si and InGaAs. A bonding layer was introduced at the InGaAs/Si interface to isolate the mismatched lattices to achieve a high-quality InGaAs film. In addition, the bonding layer can further regulate the electric field distribution in the absorption and multiplication layers. The wafer-bonded InGaAs/Si APD, structured by a polycrystalline silicon (poly-Si) bonding layer and I n 1-x G a x A s multigrading layers (x changes from 0.5 to 0.85), displayed the highest gain-bandwidth product (GBP). When the APD operates in Geiger mode, the single-photon detection efficiency (SPDE) of the photodiode is 20%, and the dark count rate (DCR) is 1 MHz at 300 K. Moreover, one finds that the DCR is lower than 1 kHz at 200 K. These results indicate that high-performance InGaAs/Si SPAD can be achieved through a wafer-bonded platform.

Development and application of a multiplex PCR method to differentiate Salmonella enterica serovar Typhimurium from its monophasic variants in pig farms.

Salmonella enterica serovar Typhimurium monophasic variants (Salmonella 4,[5],12:i:-) has increased dramatically, causing human salmonellosis and colonization in pigs. With a difference to S. Typhimurium, the monophasic variants of S. Typhimurium lose the gene cassettes encoding the second phase flagellin. To establish a rapid method to detect and differentiate the two serotypes, we analyzed the published 679 genomes of S. Typhimurium and its monophasic variants and found that no Salmonella 4,[5],12:i:- strains carry both fljB and hin genes. Therefore, we established a novel multiplex PCR method using the fljB-hin region and mdh gene as target sequences to detect and differentiate both serotypes. This method can be used to specifically detect both serotypes with a detection limit for DNA concentration at 10 pg/µL. In addition, the PCR assay successfully differentiated 36 S. Typhimurium isolates from 62 isolates of monophasic variants preserved in our laboratory from 2009 to 2017, which corresponds to the whole-genome-based serotyping results. Application of the multiplex PCR method to 60 fecal samples from a pig farm identified 11.7% (7/60) of S. Typhimurium monophasic variants, which is consistent with the whole-genome-based serotyping results. The multiplex PCR assay is a rapid and precise method for the detection of S. Typhimurium monophasic variants from samples across food production chains.

The Salmonella T3SS1 effector IpaJ is regulated by ItrA and inhibits the MAPK signaling pathway.

Invasion plasmid antigen J (IpaJ) is a protein with cysteine protease activity that is present in Salmonella and Shigella species. Salmonella enterica serovar Pullorum uses IpaJ to inhibit the NF-κB pathway and the subsequent inflammatory response, resulting in bacterial survival in host macrophages. In the present study, we performed a DNA pull-down assay and EMSA and identified ItrA, a new DeoR family transcriptional regulator that could control the expression of IpaJ by directly binding to the promoter of ipaJ. The deletion of itrA inhibited the transcription of ipaJ in Salmonella. Tn-Seq revealed that two regulators of Salmonella pathogenicity island 1 (SPI-1), namely HilA and HilD, regulated the secretion of IpaJ. The deletion of hilA, hilD or SPI-1 inhibited the secretion of IpaJ in both cultured medium and Salmonella-infected cells. In contrast, the strain with the deletion of ssrB (an SPI-2 regulator-encoding gene) displayed normal IpaJ secretion, indicating that IpaJ is an effector of the SPI-1-encoded type III secretion system (T3SS1). To further demonstrate the role of IpaJ in host cells, we performed quantitative phosphoproteomics and compared the fold changes in signaling molecules in HeLa cells infected with wild-type S. Pullorum C79-13 with those in HeLa cells infected with the ipaJ-deleted strain C79-13ΔpSPI12. Both phosphoproteomics and Western blot analyses revealed that p-MEK and p-ERK molecules were increased in C79-13ΔpSPI12- and C79-13ΔpSPI12-pipaJ(C45A)-infected cells; and Co-IP assays demonstrated that IpaJ interacts with Ras to reduce its ubiquitination, indicating that IpaJ can inhibit the activation of the MAPK signaling pathway.

Identification of two Sel1-like proteins in SPI-19 of Salmonella enterica serovar Pullorum that can mediate bacterial infection through T3SS.

The type VI secretion system (T6SS) encoded by Salmonella Pathogenicity Island 19 (SPI-19) has been confirmed to be involved in bacterial infection or colonization in hosts and in the inhibition of the host T-cell immune response. However, deletion of the core genes (clpV, vgrG, and hcp2) encoding the T6SS apparatus does not affect the phenotypes caused by SPI-19-encoded T6SS. As Salmonella infection in host cells and survival in chickens are closely associated with the type III secretion system (T3SS), RNA-Seq was performed, and the results revealed that most T3SS genes were downregulated in the C79-13ΔSPI-19 mutant. To identify the SPI-19 genes involved in regulating T3SS genes expression, we constructed mutants of genes encoding potential regulators (RS09140 and RS09275) or proteins with Sel1-like motifs (RS09150 and RS09155) and analyzed their associated phenotypes. Deletion of RS09150 and RS09155 caused the decreased bacterial infection in avian cells and bacterial colonization in chicken organs. In addition, qRT-PCR results revealed that both mutants showed decreased expression levels of regulatory genes of T3SS. The present findings demonstrate that the two Sel1-like proteins RS09150 and RS09155 in S. Pullorum SPI-19 contribute to bacterial infection in chickens by mediating the expression of T3SS genes, indicating a potential crosstalk between SPI-19 and T3SS in Salmonella.

Three-dimensional MR Elastography Depicts Liver Inflammation, Fibrosis, and Portal Hypertension in Chronic Hepatitis B or C.

Background The value of measuring mechanical properties to categorize various pathophysiologic states of the liver is as yet undetermined in chronic hepatitis B (CHB) or C (CHC). Purpose To evaluate multiparametric three-dimensional (3D) MR elastography as a means of detecting early necroinflammation, distinguishing necroinflammation from fibrosis, and gauging the severity of portal hypertension (PH) in CHB or CHC. Materials and Methods From January 2015 to September 2019, participants with CHB or CHC were prospectively enrolled from a single institution and were divided into two groups: those with liver biopsy and no evidence of PH (group 1) and those with PH and a hepatic venous pressure gradient (HVPG) measurement (group 2). For group 3, healthy volunteers were separately recruited from a nearby community. Multiple viscoelastic parameters (shear stiffness [SS], storage modulus, loss modulus, and damping ratio [DR]) were determined at 3D MR elastography at 60 Hz, and multivariable logistic or linear regression analysis was used to assess associations of mechanical parameters with histologic scores and HVPG. Results A total of 155 participants (median age, 41 years [interquartile range, 32-48 years]; 85 women) were in group 1 (training set: n = 78, validation set: n = 77), 85 participants (median age, 57 years [interquartile range, 43-61 years]; 51 women) in group 2, and 60 healthy volunteers (median age, 49 years [interquartile range, 27-64 years]; 38 men) in group 3. The liver DR was higher in participants with necroinflammation (DR, 0.13 ± 0.03) versus those without (at liver fibrosis stage F0) (DR, 0.10 ± 0.02; P < .001). Liver DR and SS together performed well in the diagnosis of necroinflammation (area under the receiver operating characteristic curve [AUC], 0.88 [95% CI: 0.79, 0.96]) and the scoring of moderate to severe activity (AUC, 0.88 [95% CI: 0.81, 0.95]) in the validation data set. Liver DR (regression coefficient [ß] = -30.3 [95% CI: -58.0, -2.5]; P = .03) and splenic SS (ß = 2.3 [95% CI: 1.7, 2.9]; P < .001) were independently associated with HVPG. Conclusion Three-dimensional MR elastography may detect early necroinflammation, distinguish necroinflammation from liver fibrosis, and correlate with hepatic venous pressure gradient in chronic hepatitis B and C. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Reeder in this issue.

The SPI-19 encoded T6SS is required for Salmonella Pullorum survival within avian macrophages and initial colonization in chicken dependent on inhibition of host immune response.

SalmonellaPathogenicity Island 19 (SPI-19) encoded type VI secretion system (T6SS) is a virulence factor present in few serotypes of S. enterica, including S. Dublin, S. Gallinarum and S. Pullorum. Comparative genomic sequence analysis revealed that the gene clusters of SPI-19 showed high homology to T6SS2 locus from avian pathogenic Escherichia coli, implying the similar T6SS locus is potentially related to the host adaption of both pathogens. Deletion of SPI-19 in S. Pullorum caused the dramatically decreased invasion into chicken LMH epithelial cells and HD-11 macrophages, and affected survival of Salmonella within both cells. In addition, deletion of SPI-19 caused the decreased colonization of S. Pullorum in chicken liver, spleen, ileum, and cecum at the initial infection stage, and induced rapid bacterial clearance. However, the SPI-19/T6SS had no effect on bacterial killing activity and induction of cytotoxicity to HD-11 macrophages. Further analysis demonstrated SPI-19/T6SS was involved in mediating the inhibition of host Th1 and Th2 immune responses, resulting in persistent colonization of S. Pullorum in hosts.

rOmpF and OMVs as efficient subunit vaccines against Salmonella enterica serovar Enteritidis infections in poultry farms.

Salmonella enterica serovar Enteritidis remains the most prevalent serotype causing human salmonellosis through the consumption of contaminated foods, especially poultry products. The development of a subunit vaccine against S. Enteritidis can not only protect chickens against Salmonella infection in the poultry industry but also cut the transmission sources. In this study, both the expressed recombinant outer membrane protein F (rOmpF) and extracted outer membrane vesicles (OMVs) were developed as subunit vaccines against S. Enteritidis challenge in chickens. Immunization with the subunit vaccine could induce not only antibody production but also strong cell-mediated immune response. Both rOmpF plus QuilA adjuvant and OMVs alone had highly protective efficacy against S. Enteritidis challenge and rapidly decreased the colonization of bacteria in chicken. These findings revealed the potential application of rOmpF and OMVs as subunit vaccines in the poultry industry.

Pancreatic adenocarcinoma: quantitative CT features are correlated with fibrous stromal fraction and help predict outcome after resection.

OBJECTIVES: To identify quantitative imaging features of contrast-enhanced computed tomography (CE-CT) that may be prognostically favorable after resection of smaller (≤ 30 mm) pancreatic ductal adenocarcinomas (PDACs) located at head. METHODS: This retrospective study included two independent cohorts (discovery cohort, n = 212; test cohort, n = 100) of patients who underwent resection of head PDACs ≤ 30 mm and preoperative CE-CT. We examined tumor and surrounding parenchymal attenuation differences (deltas), and tumor attenuation changes across phases (ratios). Semantic features of PDACs were evaluated by two radiologists. Clinicopathologic and imaging features for predicting disease-free survival (DFS) and overall survival (OS) were analyzed via multivariate Lasso-penalized Cox proportional-hazards models. Survival rates were derived by Kaplan-Meier method. RESULTS: Imaging features achieved C-indices of 0.766 (discovery cohort) and 0.739 (test cohort) for DFS, and 0.790 (discovery cohort) and 0.772 (test cohort) for OS estimates through incorporation of clinicopathologic features. The most decisive imaging feature was delta 3, denoting attenuation differences between tumor and surrounding pancreas at pancreatic phase (DFS: HR = 2.122; OS: HR = 2.375; both p < 0.001). Compared with inconspicuous (low-delta-3, < 28 HU) tumors, conspicuous (high-delta-3) tumors correlated significantly with more aggressive histologic grades (p = 0.014) and less extensive tumor fibrous stromal fractions (p < 0.001). Patients with low-delta-3 tumors ≤ 20 mm experienced the most favorable outcomes (DFS, 36 months; OS, 42 months), whereas those with high-delta-3 tumors fared poorly, regardless of tumor size (DFS, 12 months; OS, 19 months). CONCLUSIONS: Quantifiable CT imaging features reflect heterogeneous fibrous stromal fractions and histologic grades of PDAC at head locations that help stratify patients with disparate clinical outcomes. KEY POINTS: • Quantitative and semantic imaging features achieved promising results for the prognosis of resected PDAC (≤ 30 mm) at head location, through incorporation of clinicopathologic features. • Attenuation difference at tumor-parenchyma interface (delta 3) emerged as the most decisive imaging feature, enabling further stratification of patients into distinct prognostic subtypes by tumor size. • High delta 3 signifies sharper contrast between tumor and surrounding pancreas, correlating with more aggressive histologic grades and less extensive tumor fibrous stromal fractions.

Normative Pancreatic Stiffness Levels and Related Influences Established by Magnetic Resonance Elastography in Volunteers.

BACKGROUND: Large-scale normative studies of pancreatic stiffness and potential influences have yet to be pursued via magnetic resonance elastography (MRE). PURPOSE: To determine normative MRE-based pancreatic stiffness values and to examine related influential factors. STUDY TYPE: Prospective. SUBJECTS: In all, 361 volunteers (men, 199; women, 162) with a median age of 54.0 years and a median body mass index (BMI) of 22.86 kg/m2 were prospectively recruited. Those with no histories of smoking, alcohol abuse, and diabetes mellitus (DM) were grouped as healthy volunteers, designating all others as positive controls. FIELD STRENGTH/SEQUENCE: Each volunteer underwent 3.0T pancreatic MRI at a frequency of 40 Hz. ASSESSMENT: Pancreatic stiffness values, pancreatic width and volume, waist circumference, and wave distance were measured in all subjects. STATISTICAL TESTS: Multiple linear regression analyses were performed to determine variables that influence MRE-determined stiffness. RESULTS: The mean pancreatic stiffness in all volunteers was 1.20 ± 0.16 kPa. Stiffness levels in positive control volunteers proved significantly greater than levels in healthy volunteers (1.29 ± 0.17 kPa vs. 1.14 ± 0.13 kPa; P < 0.001). In multiple linear regression analysis, sex (P = 0.004), BMI (P < 0.001), pancreatic width (P = 0.005), smoking (P < 0.001), alcohol abuse (P < 0.001), and DM (P = 0.001) emerged as significant independent factors impacting pancreatic stiffness. Smoking, alcohol abuse, DM, and wide pancreas were associated with greater pancreatic stiffness (coefficients = 0.202, 0.183, 0.149, and 0.160, respectively), while reduced pancreatic stiffness corresponded with female sex and larger BMI (coefficient = -0.155 and -0.192, respectively). DATA CONCLUSION: MRE-based pancreatic stiffness values are impacted by sex, BMI, pancreatic width, smoking, alcohol abuse, and DM. Reference values are essential for future clinical studies. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;52:448-458.

The use of magnetic resonance elastography in differentiating autoimmune pancreatitis from pancreatic ductal adenocarcinoma: A preliminary study.

PURPOSE: To assess the value of magnetic resonance elastography (MRE) in patients with autoimmune pancreatitis (AIP) and in the differentiation of AIP from pancreatic ductal adenocarcinoma (PDAC). METHOD AND MATERIALS: This prospective study included 14 AIP patients, 26 PDAC patients, and 14 healthy volunteers. All participants underwent pancreatic MRE (40-Hz; 3 T scanner) at enrollment, and 7 AIP patients underwent a second MRE after initiation of steroid therapy. Pancreatic stiffness values were obtained by MRE and a new logistic regression model (the calculated Rad score) was used to combine pancreatic stiffness and the distribution and shape of high-stiffness areas for differentiation of AIP and PDAC. The area under the curve (AUC) was calculated for all parameters using receiver operating characteristic (ROC) analysis. RESULTS: Pancreatic stiffness was significantly higher (2.67 kPa [interquartile range, 2.24-3.56 kPa]) in AIP than in healthy pancreas (1.24 kPa [1.18-1.24 kPa]) and significantly lower in AIP than in PDAC (3.78 kPa [3.22-5.11 kPa]; both P < 0.05). Diffuse (n = 4 vs 1; P = 0.043) and multiple (n = 3 vs 0; P = 0.037) lesions were more common in AIP, while solitary (n = 25 vs 7; P = 0.001) and nodular lesions (n = 18 vs 2; P = 0.002) were more frequent in PDAC. Rad scores outperformed individual imaging parameters in distinguishing AIP from PDAC (AUC, 0.948 vs 0.607 to 0.782; all P < 0.05), with 84.6% specificity and 92.9% sensitivity. Pancreatic stiffness in AIP decreased significantly, from 2.66 kPa [2.29 to 3.05 kPa] to 1.55 kPa [1.43 to 1.67 kPa] (P = 0.016), during treatment. CONCLUSIONS: MRE shows promise as a quantitative imaging method for differentiating AIP from PDAC and for monitoring the treatment response in AIP.

Pancreatic stiffness response to an oral glucose load in obese adults measured by magnetic resonance elastography.

BACKGROUND: To test the feasibility of magnetic resonance elastography (MRE) for assessing changes in pancreatic stiffness of obese adults administered an oral glucose load. METHODS: MRE scans were performed on 21 asymptomatic obese volunteers (BMI ≥ 27 kg/m2) before and after receiving a 75-g oral glucose load, and repeated in 7 days without a glucose load. Shear waves at 40 and 60 Hz were introduced into the upper abdomen by a pneumatic drum driver (diameter of 12 cm). Two radiologists subjectively graded the overall quality of the wave images of the pancreas using a scale from 1 to 4, in which suboptimal image quality was considered to be scores of 1 and 2. RESULTS: Good inter-observer agreement was found for image quality at both frequencies (kappa = 0.805 for 40 Hz and 0.762 for 60 Hz). The median overall image quality score was significantly higher in 40 Hz than that of 60 Hz (4 versus 2). At 40 Hz, pancreatic stiffness in response to oral glucose had a decrease of 6.7% (pre vs post: 1.17 ±â€¯0.13 kPa vs 1.08 ±â€¯0.12 kPa; P < 0.001), whereas the change in stiffness was not significant at 60 Hz (pre vs post: 2.01 ±â€¯0.21 kPa vs 2.02 ±â€¯0.24 kPa; P = 0.695). Excellent intersession agreement was found for MRE acquisitions at 40 Hz with an overall intraclass correlation coefficient = 0.947 (95% confidence interval: 0.913-0.967). CONCLUSION: MRE at 40 Hz provides good-quality wave images and high sensitivity to changes in the mechanical properties of pancreatic tissue in obese volunteers after an oral glucose load.

Magnetic resonance elastography and T1 mapping for early diagnosis and classification of chronic pancreatitis.

BACKGROUND: Early detection and classification of chronic pancreatitis (CP) are both important and challenging. PURPOSE: To investigate the diagnostic performance of MR elastography (MRE) and T1 mapping of the pancreas for different stages of CP. STUDY TYPE: Retrospective. SUBJECTS: Clinical and imaging records of 81 patients (from 5/2015 to 7/2017) with suspected CP were analyzed. Patients were categorized into the normal control (n = 35), mild CP (n = 30), and moderate/severe CP groups (n = 16) according to the Cambridge Classification based on concordant endoscopic retrograde cholangiopancreatography or ultrasound endoscopy findings. FIELD STRENGTH/SEQUENCE: 3T pancreatic MRI, which included MRE and T1 mapping. ASSESSMENT: T1 relaxation times, pancreatic stiffness values, the main pancreatic duct (MPD) diameter, and pancreatic thickness were measured in all patients. Statistical Tests: Cutoff values of T1 relaxation times and pancreatic stiffness values for diagnosis of CP were calculated using receiver operating characteristic analysis. Associations of imaging parameters with different stages of CP were assessed using logistic regression analysis. RESULTS: Both T1 relaxation times (865 ± 220 msec vs. 1075 ± 221 msec vs. 1350 ± 139 msec) and pancreatic stiffness (1.21 ± 0.13 kPa vs. 1.50 ± 0.15 kPa vs. 1.90 ± 0.16 kPa) differed significantly (P < 0.001) among the control, mild CP, and moderate/severe CP groups. Pancreatic stiffness (>1.34 kPa) achieved significantly higher area under the curve (AUC) than T1 relaxation time (>908.4 msec) for detection of mild CP (AUC: 0.928 vs. 0.751, P = 0.011). Pancreatic stiffness values (>1.61 kPa) also achieved significantly higher AUC than T1 relaxation time (>1131.6 msec) (AUC: 0.981 vs. 0.910, P = 0.033) for diagnosing moderate/severe CP from the other two groups. Multiple regression analysis showed that T1 relaxation time and stiffness were the independent factors associated with mild CP (P = 0.025 and <0.001, respectively). DATA CONCLUSION: Both MRE and T1 mapping are promising quantitative imaging methods for evaluation of CP; MRE slightly outperformed T1 mapping. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018.