Clinical Utility of the Combined Use of CA19-9 and DUPAN-2 in Pancreatic Adenocarcinoma.

PURPOSE: Pancreatic ductal adenocarcinoma (PDAC) patients with normal carbohydrate antigen (CA) 19-9 levels can have early-stage cancer or advanced cancer without elevation of CA19-9 level; estimating their malignant potential is difficult. This study investigated the clinical utility of the combined use of preoperative CA 19-9 and Duke pancreatic monoclonal antigen type 2 (DUPAN-2) levels in patients with PDAC. METHODS: Patients who underwent curative-intent surgery for PDAC between November 2005 and December 2021 were investigated. Eligible patients were classified into four groups based on these two markers. Among patients with normal CA19-9 levels, those with normal and high DUPAN-2 levels were classified into normal/normal (N/N) and normal/high (N/H) groups, respectively. Among patients with high CA19-9 levels, those with normal and high DUPAN-2 levels were classified into high/normal (H/N) and high/high (H/H) groups, respectively. Survival rates were compared between the groups. RESULTS: Among 521 patients, the N/N, N/H, H/N, and H/H groups accounted for 25.0%, 10.6%, 35.1%, and 29.4% of patients, respectively. The proportions of resectable PDAC in the N/N and H/N groups (71.5% and 66.7%) were significantly higher than those in the N/H and H/H groups (49.1% and 54.9%) (P < 0.01). The 5-year survival rates in the N/N, N/H, H/N, and H/H groups were 66.0%, 31.1%, 34.9%, and 29.7%, respectively; the rate in the N/N group was significantly better than those in the other three groups (P < 0.0001, P < 0.0001, and P < 0.0001, respectively). CONCLUSIONS: Only patients with normal CA19-9 and DUPNA-2 values should be diagnosed with early-stage PDAC.

Recent progress in the reprogramming of nonribosomal peptide synthetases.

Nonribosomal peptide synthetases (NRPSs) biosynthesize nonribosomal peptide (NRP) natural products, which belong to the most promising resources for drug discovery and development because of their wide range of therapeutic applications. The results of genetic, biochemical, and bioinformatics analyses have enhanced our understanding of the mechanisms of the NRPS machinery. A major goal in NRP biosynthesis is to reprogram the NRPS machinery to enable the biosynthetic production of designed peptides. Reprogramming strategies for the NRPS machinery have progressed considerably in recent years, thereby increasing the yields and generating modified peptides. Here, the recent progress in NRPS reprogramming and its application in peptide synthesis are described.

Prognostic impact of peritoneal washing cytology in patients with biliary tract cancer.

PURPOSE: To elucidate the clinical significance of peritoneal washing cytology (PWC) in patients with resectable biliary tract cancer (BTC). METHODS: Clinical data of patients with BTC, who received PWC at curative intent surgery from March 2009 to December 2021, were retrospectively analyzed. Eligible patients were stratified into two groups according to positive or negative PWC. Recurrence-free survival and overall survival were compared between the two groups. Independent factors associated with positive PWC were investigated using multivariate analysis. RESULTS: Among the 284 patients analyzed, all 53 patients with ampullary carcinoma showed negative PWC and these patients were excluded. Among the remaining eligible 231 patients, 41 patients had intrahepatic cholangiocarcinoma, 55 had gall bladder carcinoma, 72 had hilar cholangiocarcinoma, and 63 had distal cholangiocarcinoma. Eleven (4.8%) patients had positive PWC, and 220 (95.2%) had negative PWC. The median recurrence-free survival in the positive and negative PWC groups were 12.0 vs. 60.7 months (p = 0.005); the median overall survival times were 17.0 vs. 60.6 months (p = 0.008), respectively. Multivariate analysis revealed that serum carbohydrate antigen 19-9 level over 80 U/mL and multiple lymph node metastasis were independently associated with positive PWC (odds ratio [OR]: 5.84, p = 0.031; OR: 5.28, p = 0.021, respectively). CONCLUSION: Patients with positive PWC exhibited earlier recurrence and shorter survival times compared with those with negative PWC.

DNAM-1 regulates Foxp3 expression in regulatory T cells by interfering with TIGIT under inflammatory conditions.

Regulatory T (Treg) cells that express forkhead box P3 (Foxp3) are pivotal for immune tolerance. Although inflammatory mediators cause Foxp3 instability and Treg cell dysfunction, their regulatory mechanisms remain incompletely understood. Here, we show that the transfer of Treg cells deficient in the activating immunoreceptor DNAM-1 ameliorated the development of graft-versus-host disease better than did wild-type Treg cells. We found that DNAM-1 competes with T cell immunoreceptor with Ig and ITIM domains (TIGIT) in binding to their common ligand CD155 and therefore regulates TIGIT signaling to down-regulate Treg cell function without DNAM-1-mediated intracellular signaling. DNAM-1 deficiency augments TIGIT signaling; this subsequently inhibits activation of the protein kinase B-mammalian target of rapamycin complex 1 pathway, resulting in the maintenance of Foxp3 expression and Treg cell function under inflammatory conditions. These findings demonstrate that DNAM-1 regulates Treg cell function via TIGIT signaling and thus, it is a potential molecular target for augmenting Treg function in inflammatory diseases.

Compounds Designs of CK2α Inhibitors Derived from Virtual Screening Hit Compounds by Computational Chemistry with Crystallography.

Protein kinase CK2 type α (CK2α) inhibitors are expected to be a new anticancer drug and a treatment for nephritis. Virtual screening for CK2α inhibitors has been conducted and active compounds with various scaffolds have been obtained. Research on compound optimization is currently in progress for some of them with the aim of improving their activity. This process involves the combination of various computational chemistry methods and crystal analyses. In this review, case studies of structure-based compound designs that have efficiently improved the activity of screening hit compounds, including compounds with a thiadiazole ring and a purine scaffold, are introduced.

Clinical and safety outcomes of simultaneous bilateral total knee arthroplasty for Japanese octogenarian patients: a retrospective analysis.

PURPOSE: The demand for simultaneous bilateral total knee arthroplasty (SiBTKA) in older adults is expected to increase with an aging population, thus necessitating evaluating its efficacy and safety. However, there is limited information regarding the clinical outcomes of SiBTKA in older adults, particularly in octogenarians. We aimed to assess the clinical outcomes and safety of SiBTKA in Japanese patients aged ≥ 80 years. METHODS: Of the 176 consecutive knees that underwent SiBTKA between July 2016 and January 2022 at our hospital, 172 were selected. They were divided into two groups according to the patient age as follows: the octogenarian group (≥ 80 years, 74 knees) and the younger control group (< 80 years, 98 knees). In addition, we assessed their preoperative clinical information, clinical outcomes using the Knee Society Score for knee (KSS-K) and function (KSS-F), and the incidence of early (≤ 90 days) and late (> 90 days) postoperative complications. RESULTS: The mean follow-up period was 3.5 years. The KSS-K scores of both groups improved postoperatively than that preoperatively. Both preoperative and postoperative KSS-F scores were lower in the octogenarians; however, their improvement rates were similar to those of the younger controls. We observed no significant intergroup differences in early or late postoperative complications, including infection, systemic complications, periprosthetic fractures, aseptic loosening, and mortality. CONCLUSION: SiBTKA for octogenarians had clinical outcomes and postoperative complication incidence similar to that for younger controls. Therefore, SiBTKA may be a safe and effective treatment option for octogenarians with painful bilateral knee deformities.

System truncation accelerates binding affinity calculations with the fragment molecular orbital method: A benchmark study.

The fragment molecular orbital (FMO) method is a fast quantum-mechanical method that divides systems into pieces of fragments and performs ab initio calculations. The system truncation enables further speed improvement. In this article, we systematically study the effects of system truncations on binding affinity calculations obtained with FMO in combination with either the polarizable continuum model (FMO/PCM) or in combination with the Møller-Plesset method (FMO-MP2). We have used five protein complexes with ligands of several charged states. The calculated binding energies of the size variants of the truncated system, including only a restricted number of atoms around the ligand, are compared to the energy obtained from a full system. The result shows that the systems could be truncated to a radius of 8 Å from neutral ligands within an error of 0.7 kcal/mol, and 12 Å from charged ligands within an error of 1.1 kcal/mol for calculating the binding energy in solution.

DNAM-1 promotes inflammation-driven tumor development via enhancing IFN-γ production.

DNAM-1 is an activating immunoreceptor on T cells and natural killer (NK) cells. Expression levels of its ligands, CD155 and CD112, are up-regulated on tumor cells. The interaction of DNAM-1 on CD8+ T cells and NK cells with the ligands on tumor cells plays an important role in tumor immunity. We previously reported that mice deficient in DNAM-1 showed accelerated growth of tumors induced by the chemical carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). Contrary to those results, we show here that tumor development induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) together with DMBA was suppressed in DNAM-1-deficient mice. In this model, DNAM-1 enhanced IFN-γ secretion from conventional CD4+ T cells to promote inflammation-related tumor development. These findings suggest that, under inflammatory conditions, DNAM-1 contributes to tumor development via conventional CD4+ T cells.

Relapse rate and predictors of relapse after cessation of glucocorticoid maintenance therapy in type 1 autoimmune pancreatitis: a multicenter retrospective study.

BACKGROUND: Type 1 autoimmune pancreatitis responds well to glucocorticoid therapy with a high remission rate. Moreover, glucocorticoid maintenance therapy can help prevent relapse. However, the relapse rate following cessation of long-term glucocorticoid therapy is unknown. The aim of this study was to clarify the relapse rate and predictors of relapse following long-term glucocorticoid therapy cessation. METHODS: We analyzed 94 patients who achieved remission after undergoing glucocorticoid therapy, discontinued treatment after at least 6 months of maintenance therapy, and were subsequently followed up for at least 6 months. The patients were divided into three groups based on treatment duration (< 18, 18-36, and ≥ 36 months), and their relapse rates were compared. Univariate and multivariate analyses of clinical factors were conducted to identify relapse predictors. RESULTS: After discontinuing glucocorticoid therapy, relapse was observed in 43 (45.7%) patients, with cumulative relapse rates of 28.2% at 1 year, 42.1% at 3 years, 47.0% at 5 years, and a plateau of 77.6% at 9 years. Of the 43 patients who relapsed, 25 (58.1%) relapsed within 1 year after after cessation of glucocorticoid therapy. Relapse and cumulative relapse rates did not differ significantly according to treatment duration. In the multivariate analysis, an elevated serum IgG4 level at the time of glucocorticoid cessation was found to be an independent predictor of relapse (hazard ratio, 4.511; p < 0.001). CONCLUSIONS: A high relapse rate occurred after cessation of glucocorticoid maintenance therapy, regardless of the duration of maintenance therapy, especially within the first year after cessation. However, the normalization of long-term serum IgG4 levels may be a factor in considering cessation.

Difficulty of adjuvant chemotherapy administration in patients with biliary tract cancer.

PURPOSE: This study aimed to elucidate the difficulty of adjuvant chemotherapy administration in patients with biliary tract carcinoma (BTC). METHODS: Clinical data of patients with BTC who underwent curative-intent surgery were retrospectively analyzed. The eligible patients were stratified into two groups according to the presence or absence of adjuvant chemotherapy administration (adjuvant and non-adjuvant groups), and the clinicopathological features were compared between the two groups. The ratios of adjuvant chemotherapy administration were investigated in each surgical procedure. Independent factors associated with no administration of adjuvant chemotherapy were analyzed using multivariate analyses. RESULTS: Among 168 eligible patients, 141 (83.9%) received adjuvant chemotherapy (adjuvant group), while 27 (16.1%) did not (non-adjuvant group). The most common surgical procedure was pancreaticoduodenectomy in the adjuvant group, and it was hepatectomy with extrahepatic bile duct resection (BDR) in the non-adjuvant group, respectively. The rate of no adjuvant chemotherapy was significantly higher in patients who underwent hepatectomy with BDR than in those who underwent other surgeries (p < 0.001). The most common cause of no adjuvant chemotherapy was bile leak in 12 patients, which occurred after hepatectomy with BDR in ten patients. Multivariate analyses revealed that hepatectomy with BDR and preoperative anemia were independently associated with no adjuvant chemotherapy (p < 0.001 and p < 0.001, respectively). CONCLUSIONS: Hepatectomy with BDR and subsequent refractory bile leak can be the obstacle to adjuvant chemotherapy administration in patients with BTC.

Fragment Molecular Orbital Based Affinity Prediction toward Pyruvate Dehydrogenase Kinases: Insights into the Charge Transfer in Hydrogen Bond Networks.

The fragment molecular orbital (FMO) method is a fast quantum-mechanics method that divides systems into pieces of fragments and performs ab initio calculations. The method has been expected to improve the accuracy of describing protein-ligand interactions by incorporating electronic effects. In this article, FMO calculation with solvation methods were applied to the affinity prediction at the ATP-binding site of PDHK4. As the ionized aspartic acid lies at the center and is involved in the complex hydrogen bond networks, this system has turned out to be a difficult target to describe by traditional molecular-mechanics method. In the FMO calculation with the polarizable continuum model (PCM) solvation method, a considerable amount of charge (-0.27e) was transferred from the ionized aspartate to the surrounding residues. We found that using FMO with the PCM solvation method was important to increase the correlation, and by incorporating the ligand deformation energy, the correlation was improved to R = 0.81 for whole twelve compounds and R = 0.91 without one outlier compound.

Design, Synthesis and Structure-Activity Relationship Studies of Protein Kinase CK2 Inhibitors Containing a Purine Scaffold.

Protein kinase CK2 (CK2) is involved in the suppression of gene expression, protein synthesis, cell proliferation, and apoptosis, thus making it a target protein for the development of therapeutics toward cancer, nephritis, and coronavirus disease 2019. Using the solvent dipole ordering-based method for virtual screening, we identified and designed new candidate CK2α inhibitors containing purine scaffolds. Virtual docking experiments supported by experimental structure-activity relationship studies identified the importance of the 4-carboxyphenyl group at the 2-position, a carboxamide group at the 6-position, and an electron-rich phenyl group at the 9-position of the purine scaffold. Docking studies based on the crystal structures of CK2α and inhibitor (PDBID: 5B0X) successfully predicted the binding mode of 4-(6-carbamoyl-8-oxo-9-phenyl-8,9-dihydro-7H-purin-2-yl) benzoic acid (11), and the results were used to design stronger small molecule targets for CK2α inhibition. Interaction energy analysis suggested that 11 bound around the hinge region without the water molecule (W1) near Trp176 and Glu81 that is frequently reported in crystal structures of CK2α inhibitor complexes. X-ray crystallographic data for 11 bound to CK2α was in very good agreement with the docking experiments, and consistent with activity. From the structure-activity relationship (SAR) studies presented here, 4-(6-Carbamoyl-9-(4-(dimethylamino)phenyl)-8-oxo-8,9-dihydro-7H-purin-2-yl) benzoic acid (12) was identified as an improved active purine-based CK2α inhibitor with an IC50 of 4.3 µM. These active compounds with an unusual binding mode are expected to inspire new CK2α inhibitors and the development of therapeutics targeting CK2 inhibition.

Preoperative incidence and risk factors of deep vein thrombosis in Japanese patients undergoing total hip arthroplasty.

PURPOSE: Preoperative deep vein thrombosis (DVT) is a risk factor for postoperative venous thromboembolism (VTE), causing severe mortality. Early detection of preoperative DVT is essential to prevent postoperative VTE. However, little is known regarding preoperative DVT in patients undergoing major surgery. The present study aimed to determine the incidence and risk factors of preoperative DVT in patients admitted for total hip arthroplasty (THA). METHODS: From August 2017 to September 2022, 243 patients admitted for THA at our institution were enrolled in this study. Patients medical records and preoperative laboratory data were retrospectively collected. According to the results of lower-limb ultrasonography, patients were divided into either the non-DVT (n = 136) or DVT (n = 43) group. The incidence of DVT and independent risk factors for preoperative DVT were investigated using univariate and multivariate logistic regression analyses. RESULTS: The mean age was 74.0 ± 8.4 years. Preoperative DVT was diagnosed in 43 of the 243 (17.7%) patients. The risk of DVT was significantly high (p < 0.05) in patients with advanced age, increased D-dimer levels, and malnutrition status, as assessed by the Geriatric Nutritional Risk Index (GNRI). Multivariate analysis showed that advanced age, increased D-dimer level, and malnutrition status assessed by the GNRI were independent risk factors for preoperative DVT. CONCLUSION: A high incidence of preoperative DVT was observed in patients undergoing THA. Advanced age, increased D-dimer levels, and malnutrition assessed by the GNRI increased the risk of preoperative DVT. Screening high-risk subgroups for preoperative DVT is necessary to prevent postoperative VTE.

Clinical and radiological outcomes of total hip arthroplasty in octogenarian patients using a three-dimensional porous titanium cup: a retrospective analysis in Japanese patients.

PURPOSE: Osteointegration of a three-dimensional (3D) porous titanium material has been experimentally proven, but only a few studies have shown the clinical outcomes of a 3D porous titanium cup in the Japanese elderly population. The purpose of this study was to compare the short-and-medium term clinical and radiographic results of total hip arthroplasty (THA) using a 3D porous titanium cup in patients aged ≥ 80 (octogenarians) versus those aged < 80 (younger controls). METHODS: A total of 104 hips that underwent THA using a 3D porous titanium cup (SQRUM TT, Kyocera Medical) were enrolled in the study and were divided into two groups according to age: the octogenarian group (≥ 80, n = 42) and the younger control group (< 80, n = 62). Furthermore, we evaluated patient characteristics, clinical outcomes determined by the Japanese Orthopedic Association score, cup alignment, and incidence of radiolucent lines around the cup. RESULTS: The mean follow-up period was 4.2 and 4.0 years (p = 0.29) for octogenarians and younger controls, respectively. The clinical outcomes were excellent, and no revision surgery occurred until the last follow-up in both groups. The number of patients with radiolucent lines at the final evaluation was 21 of 62 (33.9%) in younger controls and 16 of 42 (38.1%) in octogenarians. CONCLUSION: THA with 3D porous titanium cup for octogenarians had similar clinical outcomes and incidence of radiolucent lines as those of younger controls, suggesting that the 3D porous titanium cup may be useful in THA for octogenarians. Further investigations will confirm its long-term outcomes.

Bivalent binding mode of an amino-pyrazole inhibitor indicates the potentials for CK2α1-selective inhibitors.

Casein kinase 2 (CK2) is a vital protein kinase that consists of two catalytic subunits (CK2α1 and/or CK2α2) and two regulatory subunits (CK2ß). CK2α1 is a drug target for nephritis and cancers, while CK2α2 is a serious off-target because its inhibition causes testicular toxicity. High similarity between the isozymes CK2α1 and CK2α2 make it difficult to design CK2α1-specific inhibitors. Herein, the crystal structures of CK2α1 and CK2α2 complexed with a 3-amino-pyrazole inhibitor revealed the remarkable differences in the protein-inhibitor interaction modes. This inhibitor bound to the ATP binding sites of both isozymes in apparently distinct orientations. In addition, another molecule of this inhibitor bound to CK2α1, but not to CK2α2, at the CK2ß protein-protein interface. Binding energy calculations and biochemical experiments suggested that this inhibitor possesses the conventional ATP-competitive characteristics with moderate allosteric function in a molecular glue mechanism. These results will assist the potential design of potent and selective CK2α1 inhibitors.

Optimal indication of endoscopic retrograde pancreatography-based cytology in the preoperative pathological diagnosis of pancreatic ductal adenocarcinoma.

BACKGROUND: Endoscopic ultrasound-guided fine needle aspiration (EUS-FNA) is extremely useful for pathological diagnosis of pancreatic ductal adenocarcinoma (PDAC); however, puncturing is difficult in some cases, and there is a risk of needle tract seeding. This study evaluated the indications for endoscopic retrograde pancreatography-based (ERP)-based cytology for the preoperative diagnosis of PDAC. METHODS: This study included 267 patients with PDAC who underwent preoperative ERP. The diagnostic performance of ERP-based cytology for PDAC was evaluated based on the sample collection method (pancreatic juice cytology [PJC] during ERP, brush cytology, PJC via endoscopic nasopancreatic drainage [ENPD] catheter), lesion site (pancreatic head, body/tail), and lesion size (≤10 mm, 10-20 mm, >20 mm), and compared with the diagnostic performance of EUS-FNA. RESULTS: The overall sensitivity of ERP-based cytology was 54.9%; sensitivity by the sampling method was 34.7% for PJC during ERP, 65.8% for brush cytology, and 30.8% for PJC via an ENPD catheter. The sensitivity of EUS-FNA was 85.3%. Brush cytology and PJC via an ENPD catheter were performed more often in pancreatic body/tail lesions than in head lesions (P = 0.016 and P < 0.001, respectively), and the overall sensitivity of ERP-based cytology was better for body/tail lesions (63.2% vs. 49.0%, P = 0.025). The sensitivities of ERP-based cytology and EUS-FNA in diagnosing PDAC ≤10 mm were 92.3% and 33.3%, respectively. Post-ERP pancreatitis was observed in 22 patients (8.2%) and significantly less common with ENPD catheters (P = 0.002). CONCLUSIONS: ERP-based cytology may be considered the first choice for pathological diagnosis of PDAC ≤10 mm and in the pancreatic body/tail.

[A case of Caroli's disease associated with intrahepatic cholangiocarcinoma].

A 65-year-old male with Caroli's disease had a fast rise in serum CA19-9 level during follow-up. Contrast-enhanced computed tomography (CT) revealed an irregular mass with a 3cm diameter, showing ring-like and delayed improvement in segment 8 of the liver. Gadolinium ethoxybenzyl diethylenetriamine penta-acetic acid-enhanced magnetic resonance imaging (MRI) demonstrated a mass with the hypointense signal on T1-weighted images, mildly hyperintense signal on T2-weighted images, and hypointense signal in the hepatobiliary phase. Positron emission tomography/CT revealed the absorption of (18) F-fluorodeoxyglucose in the hepatic mass and a nodule in the anterior mediastinum. The patient was diagnosed with intrahepatic cholangiocarcinoma and supraclavicular lymph node metastasis and had partial hepatectomy and lymph node dissection. Caroli's disease is an uncommon congenital condition with myriad small cystic dilatations of the peripheral intrahepatic bile duct as the primary lesion. The disease is not only often associated with recurrent cholangitis and hepatolithiasis but is also a high-risk group of intrahepatic cholangiocarcinoma. Caroli's disease requires regular screening for intrahepatic cholangiocarcinoma utilizing suitable imaging modalities, such as CT and MRI, as well as tumor marker testing.

Elongation of the side chain by linear alkyl groups increases the potency of salacinol, a potent α-glucosidase inhibitor from the Ayurvedic traditional medicine "Salacia," against human intestinal maltase.

Four chain-extended analogs (12a-12d) and two related de-O-sulfonated analogs (13a and 13c) by introducing alkyl groups (a: R = C3H7, b R = C6H13, c: R = C8H17, d: R = C10H21) to the side chains of salacinol (1), a natural α-glucosidase inhibitor from Ayurvedic traditional medicine "Salacia", were synthesized. The α-glucosidase inhibitory activities of all the synthesized analogs were evaluated in vitro. Against human intestinal maltase, the inhibitory activities of 12a and 13a with seven-carbon side chain were equal to that of 1. In contrast, analogs (12b-12d, and 13c) exhibited higher level of inhibitory activity against the same enzyme than 1 and had equal or higher potency than those of the clinically used anti-diabetics, voglibose, acarbose, and miglitol. Thus, elongation of the side chains of 1 was effective for specifically increasing the inhibitory activity against human intestinal maltase.

Adding Delayed Phase Images to Dual-Phase Contrast-Enhanced CT Increases Sensitivity for Small Pancreatic Ductal Adenocarcinoma.

BACKGROUND. Contrast-enhanced CT performed for pancreatic ductal adeno-carcinoma (PDAC) detection traditionally uses a dual-phase (pancreatic and portal venous) protocol. However, PDAC may exhibit isoattenuation in these phases, hindering detection. OBJECTIVE. The purpose of this study was to assess the impact on diagnostic performance in detection of small PDAC when a delayed phase is added to dual-phase contrast-enhanced CT. METHODS. A database of 571 patients who underwent triple-phase (pancreatic, portal venous, and delayed) contrast-enhanced MDCT between January 2017 and March 2020 for suspected pancreatic tumor was retrospectively reviewed. A total of 97 patients had pathologically confirmed small PDAC (mean size, 22 mm; range, 7-30 mm). Twenty control patients had no pancreatic tumor suspected on CT, on initial MRI and follow-up CT, or on MRI after 12 months or longer. Three radiologists independently reviewed dual-phase and triple-phase images. Two additional radiologists assessed tumors' visual attenuation on each phase, reaching consensus for differences. Performance of dual- and triple-phase images were compared using ROC analysis, McNemar test, and Fisher exact test. RESULTS. AUC was higher (p < .05) for triple-phase than dual-phase images for all observers (observer 1, 0.97 vs 0.94; observer 2, 0.97 vs 0.94; observer 3, 0.97 vs 0.95). Sensitivity was higher (p < .001) for triple-phase than dual-phase images for all observers (observer 1, 74.2% [72/97] vs 59.8% [58/97]; observer 2, 88.7% [86/97] vs 71.1% [69/97]; observer 3, 86.6% [84/97] vs 72.2% [70/97]). Specificity, PPV, and NPV did not differ between image sets for any reader (p ≥ .05). Seventeen tumors showed pancreatic phase visual isoattenuation, of which nine showed isoattenuation and eight hyperattenuation in the delayed phase. Of these 17 tumors, 16 were not detected by any observer on dual-phase images; of these 16, six were detected by at least two observers and five by at least one observer on triple-phase images. Visual attenuation showed excellent interob-server agreement (κ = 0.89-0.96). CONCLUSION. Addition of a delayed phase to pancreatic and portal venous phase CT increases sensitivity for small PDAC without loss of specificity, partly related to delayed phase hyperattenuation of some small PDACs showing pancreatic phase isoattenuation. CLINICAL IMPACT. Addition of a delayed phase may facilitate earlier PDAC detection and thus improved prognosis.

Selection of the optimal tyrosine hydroxylation enzyme for (S)-reticuline production in Escherichia coli.

We have constructed an Escherichia coli-based platform producing (S)-reticuline, an important intermediate of benzylisoquinoline alkaloids (BIAs), using up to 14 genes. (S)-reticuline was produced from a simple carbon source such as glucose and glycerol via L-DOPA, which is synthesized by hydroxylation of L-tyrosine, one of the rate-limiting steps of the reaction. There are three kinds of enzymes catalyzing tyrosine hydroxylation: tyrosinase (TYR), tyrosine hydroxylase (TH), and 4-hydroxyphenylacetate 3-monooxygenase (HpaBC). Here, to further improve (S)-reticuline production, we chose eight from these three kinds of tyrosine hydroxylation enzymes (two TYRs, four THs, and two HpaBCs) derived from various organisms, and examined which enzyme was optimal for (S)-reticuline production in E. coli. TH from Drosophila melanogaster was the most suitable for (S)-reticuline production under the experimental conditions tested. We improved the productivity by genome integration of a gene set for L-tyrosine overproduction, introducing the regeneration pathway of BH4, a cofactor of TH, and methionine addition to enhance the S-adenosylmethionine supply. As a result, the yield of (S)-reticuline reached up to 384 µM from glucose in laboratory-scale shake flask. Furthermore, we found three inconsistent phenomena: an inhibitory effect due to additional gene expression, conflicts among the experimental conditions, and interference of an upstream enzyme from an additional downstream enzyme. Based on these results, we discuss future perspectives and challenges of integrating multiple enzyme genes for material production using microbes. Graphical abstract The optimal tyrosine hydroxylation enzyme for (S)-reticuline production in Escherichia coli KEY POINTS: • There are three types of enzymes catalyzing tyrosine hydroxylation reaction: tyrosinase, tyrosine hydroxylase, and 4-hydroxyphenylacetate 3-monooxygenase. • Tyrosine hydroxylase from Drosophila melanogaster exhibited the highest activity and was suitable for (S)-reticuline production in E. coli. • New insights were provided on constructing an alkaloid production system with multi-step reactions in E. coli.