Washout-parametric imaging with Sonazoid for enhanced differentiation of focal liver lesions.

PURPOSE: The study aimed to compare the diagnostic performance of washout-parametric imaging (WOPI) with that of conventional contrast-enhanced ultrasound (cCEUS) in differentiating focal liver lesions (FLLs). METHODS: A total of 181 FLLs were imaged with contrast-enhanced ultrasound using Sonazoid, and the recordings were captured for 10 minutes in a prospective setting. WOPI was constructed from three images, depicting the arterial phase (peak enhancement), the early portal venous phase (1-minute post-injection), and the vasculo-Kupffer phase (5 or 10 minutes post-injection). The intensity variations in these images were color-coded and superimposed to produce a single image representing the washout timing across the lesions. From the 181 FLLs, 30 hepatocellular carcinomas (HCCs), 30 non-HCC malignancies, and 30 benign lesions were randomly selected for an observer study. Both techniques (cCEUS and WOPI) were evaluated by four off-site readers. They classified each lesion as benign or malignant using a continuous rating scale, with the endpoints representing "definitely benign" and "definitely malignant." The diagnostic performance of cCEUS and WOPI was compared using the area under the receiver operating characteristic curve (AUC) with the DeLong test. Interobserver agreement was assessed using the intraclass correlation coefficient (ICC). RESULTS: The difference in average AUC values between WOPI and cCEUS was 0.0062 (95% confidence interval, -0.0161 to 0.0285), indicating no significant difference between techniques. The interobserver agreement was higher for WOPI (ICC, 0.77) than cCEUS (ICC, 0.67). CONCLUSION: The diagnostic performance of WOPI is comparable to that of cCEUS in differentiating FLLs, with superior interobserver agreement.

Eosinophilic pleural effusion due to Staphylococcus epidermidis infection: A case report.

Eosinophilic pleural effusion is rare, and the cause is often obscure. A 73-year-old man with no relevant medical history presented with exertional dyspnea. Chest imaging revealed left-sided pleural effusion, and pleural fluid examination revealed eosinophilic pleural effusion. Blood tests revealed an increased peripheral blood eosinophil count and elevated Immunoglobulin E levels. Staphylococcus epidermidis was detected in pleural specimens collected via thoracoscopy. Antimicrobial therapy targeting Staphylococcus epidermidis resolved the eosinophilic pleural effusion and elevated peripheral blood eosinophil count. Staphylococcus epidermidis infection may be considered as a cause of eosinophilic pleural effusion when the diagnosis is difficult.

Tyrosine phenol-lyase inhibitor quercetin reduces fecal phenol levels in mice.

Tyrosine phenol-lyase (TPL), which is expressed in intestinal bacteria, catalyzes the formation of phenol from the substrate L-Tyr. Bacterial metabolite phenol and the sulfate conjugate (phenyl sulfate) are known as a type of uremic toxins, some of which exert cytotoxicity. Therefore, pathologically elevated phenol and phenyl sulfate levels are strongly implicated in the etiology and outcome of uremia. In this study, we explored the inhibitory effects of dietary polyphenols on TPL-catalyzed phenol production using a TPL activity assay. Quercetin, one of the most popular polyphenols, exhibited the strongest inhibitory activity (Ki = 19.9 µM). Quercetin competitively inhibited TPL, and its activity was stronger than that of a known TPL inhibitor (Tyr analog; 2-aza-Tyr, Ki = 42.0 µM). Additionally, quercetin significantly inhibited phenol production in TPL-expressing bacterial cultures (Morganella morganii and Citrobacter koseri) and Tyr-rich (5%) diet-fed C57BL/6J mouse feces. Our findings suggest that quercetin is the most promising polyphenol for reducing phenol levels. Because quercetin has a low gastrointestinal absorption rate, TPL inhibition in the intestinal tract by quercetin may be an effective strategy for treating uremia.

Structural and Functional Analyses of Inhibition of Human Dihydroorotate Dehydrogenase by Antiviral Furocoumavirin.

Natural products are important sources of seed compounds for drug discovery. However, it has become difficult in recent years to discover new compounds with valuable pharmacological activities. On the other hand, among the vast number of natural products that have been isolated so far, a considerable number of compounds with specific biological activities are thought to be overlooked in screening that uses biological activity as an index. Therefore, it is conceivable that such overlooked useful compounds may be found by screening compound libraries that have been amassed previously through specific assays. Previously, NPD723, a member of the Natural Products Depository library comprised of a mixture of natural and non-natural products developed at RIKEN, and its metabolite H-006 were found to inhibit growth of various cancer cells at low nanomolar half-maximal inhibitory concentration. Subsequent analysis revealed that H-006 strongly inhibited human dihydroorotate dehydrogenase (DHODH), the rate-limiting enzyme in the de novo pyrimidine biosynthetic pathway. Here, we elucidated the crystal structure of the DHODH-flavin mononucleotide-orotic acid-H-006 complex at 1.7 Å resolution to determine that furocoumavirin, the S-enantiomer of H-006, was the actual inhibitor. The overall mode of interaction of furocoumavirin with the inhibitor binding pocket was similar to that described for previously reported tight-binding inhibitors. However, the structural information together with kinetic characterizations of site-specific mutants identified key unique features that are considered to contribute to the sub-nanomolar inhibition of DHODH by furocoumavirin. Our finding identified new chemical features that could improve the design of human DHODH inhibitors.

Structural basis for intra- and intermolecular interactions on RAD9 subunit of 9-1-1 checkpoint clamp implies functional 9-1-1 regulation by RHINO.

Eukaryotic DNA clamp is a trimeric protein featuring a toroidal ring structure that binds DNA on the inside of the ring and multiple proteins involved in DNA transactions on the outside. Eukaryotes have two types of DNA clamps: the replication clamp PCNA and the checkpoint clamp RAD9-RAD1-HUS1 (9-1-1). 9-1-1 activates the ATR-CHK1 pathway in DNA damage checkpoint, regulating cell cycle progression. Structure of 9-1-1 consists of two moieties: a hetero-trimeric ring formed by PCNA-like domains of three subunits and an intrinsically disordered C-terminal region of the RAD9 subunit, called RAD9 C-tail. The RAD9 C-tail interacts with the 9-1-1 ring and disrupts the interaction between 9-1-1 and DNA, suggesting a negative regulatory role for this intramolecular interaction. In contrast, RHINO, a 9-1-1 binding protein, interacts with both RAD1 and RAD9 subunits, positively regulating checkpoint activation by 9-1-1. This study presents a biochemical and structural analysis of intra- and inter-molecular interactions on the 9-1-1 ring. Biochemical analysis indicates that RAD9 C-tail binds to the hydrophobic pocket on the PCNA-like domain of RAD9, implying that the pocket is involved in multiple protein-protein interactions. The crystal structure of the 9-1-1 ring in complex with a RHINO peptide reveals that RHINO binds to the hydrophobic pocket of RAD9, shedding light on the RAD9-binding motif. Additionally, the study proposes a structural model of the 9-1-1-RHINO quaternary complex. Together, these findings provide functional insights into the intra- and inter-molecular interactions on the front side of RAD9, elucidating the roles of RAD9 C-tail and RHINO in checkpoint activation.

Utility of Coproporphyrin-I Determination in First-in-Human Study for Early Evaluation of OATP1B Inhibitory Potential Based on Investigation of Ensitrelvir, an Oral SARS-CoV-2 3C-Like Protease Inhibitor.

Coproporphyrin-I (CP-I) has been investigated as an endogenous biomarker of organic anion transporting polypeptide (OATP) 1B. Here, we determined the CP-I concentrations in a cocktail drug-drug interaction (DDI) study of ensitrelvir to evaluate the OATP1B inhibitory potential because ensitrelvir had increased plasma concentrations of rosuvastatin in this study, raising concerns about breast cancer resistance protein and OATP1B inhibition. Furthermore, CP-I concentrations were compared between active and placebo groups in a first-in-human (FIH) study of ensitrelvir to verify whether the OATP1B inhibitory potential could be estimated at an early drug development stage. In the cocktail DDI study, CP-I did not differ between with/without administration of ensitrelvir, indicating that ensitrelvir has no OATP1B inhibitory effect. Although there were some individual variabilities in CP-I concentrations among the treatment groups in the FIH study, the normalization of CP-I concentrations with pre-dose values minimized these variabilities, suggesting that this normalized method would be helpful for comparing the CP-I from different participants. Finally, we concluded that CP-I concentrations were not affected by ensitrelvir in the FIH study. These results suggested that the CP-I determination in an FIH study and its normalized method can be useful for an early evaluation of the OATP1B-mediated DDI potential in humans.

Uncommon Arrangement of Self-resistance Allows Biosynthesis of de novo Purine Biosynthesis Inhibitor that Acts as an Immunosuppressor.

(-)-FR901483 (1) isolated from the fungus Cladobotryum sp. No.11231 achieves immunosuppression via nucleic acid biosynthesis inhibition rather than IL-2 production inhibition as accomplished by FK506 and cyclosporin A. Recently, we identified the frz gene cluster for the biosynthesis of 1. It contains frzK, a gene homologous to phosphoribosyl pyrophosphate amidotransferase (PPAT)that catalyzes the initial step of de novo purine biosynthesis. We speculated that frzK encodes a PPAT that escapes inhibition by 1 and functions as a self-resistance enzyme (SRE) for the producing host. Nevertheless, details remained elusive. Here, we report the biochemical and structural analyses of FrzK and its Escherichia coli counterpart, PurF. Recombinantly produced FrzK exhibited PPAT activity, albeit weaker than PurF, but evaded strong inhibition by 1. These results confirmed that the target of 1 is PPAT, and FrzK acts as an SRE by maintaining the de novo purine biosynthetic capability in the presence of 1. To understand how FrzK evades inhibition by 1, we determined the crystal structure of PurF in the complex with 1 and constructed a homology model of FrzK. Sequence and structural analyses of various PPATs identified that many residues unique to FrzK occur near the Flexible Loop that remains disordered when inactive but becomes ordered and covers up the active site upon activation by substrate binding. Kinetic characterizations of mutants of the unique residues revealed that the resistance of FrzK against 1 may be conferred by structurally predisposing the Flexible Loop to the active, closed conformation even in the presence of 1.

[Relapsed/refractory Philadelphia chromosome-positive acute lymphoblastic leukemia responding to retreatment with inotuzumab ozogamicin].

A 72-year-old man with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL) was treated with dasatinib (week1: 50 mg/day, week2: 70 mg/day, week3-: 100 mg/day) and prednisolone from June 2017. However, in January 2018, it relapsed with the T315I mutation. Although the treatment was changed to ponatinib 30 mg/day, he experienced a second relapse in June 2018. Following confirmation of CD22 positivity, he was treated with three cycles of inotuzumab ozogamicin (InO), resulting in CR. He was CR for 2.9 years before relapsing for the third time in May 2021. Because the patient was still CD22-positive, InO was given again, and the patient achieved CR at the end of the second cycle. We had a case where re-administering InO was effective as a salvage therapy for relapsed/refractory Ph+ALL (r/r Ph+ALL) in an elderly patient.

Genetic dissection of HLA-DRB1*15:01 and XL9 region variants in Japanese patients with systemic lupus erythematosus: primary role for HLA-DRB1*15:01.

OBJECTIVE: Major histocompatibility complex strongly contributes to susceptibility to systemic lupus erythematosus (SLE). In the European populations, HLA-DRB1*03:01 and DRB1*15:01 are susceptibility alleles, but C4 locus was reported to account for the association of DRB1*03:01. With respect to DRB1*15:01, strong linkage disequilibrium with a variant rs2105898T in the XL9 region, located between DRB1 and DQA1 and regulates HLA-class II expression levels, was reported; however, the causative allele remains to be determined. Leveraging the genetic background of the Japanese population, where DRB1*15:01 and DRB1*15:02 are commonly present and only DRB1*15:01 is associated with SLE, this study aimed to distinguish the genetic contribution of DRB1*15:01 and XL9 variants. METHODS: Among the XL9 variants, two (rs2105898 and rs9271593) previously associated variants in the European populations and two (rs9271375 and rs9271378) which showed a trend towards association in a Japanese Genome-Wide Association Study were selected. Associations of the XL9 variants and HLA-DRB1 were examined in 442 Japanese SLE patients and 779 controls. Genotyping of the XL9 variants was performed by TaqMan SNP Genotyping Assay and direct sequencing. HLA-DRB1 alleles were determined by PCR-reverse sequence-specific oligonucleotide probes. RESULTS: Among the XL9 variants, associations of rs2105898T and rs9271593C were replicated in the Japanese population. However, these associations became no longer significant when conditioned on DRB1*15:01. In contrast, the association of DRB1*15:01 remained significant after conditioning on the XL9 variants. CONCLUSION: In the Japanese population, HLA-DRB1*15:01 was found to be primarily associated with SLE, and to account for the apparent association of XL9 region.

Risk-adjusted hazard analysis of survival after pulmonary metastasectomy for uterine malignancies in 319 cases.

Objective: There is little evidence of the outcome of pulmonary metastasectomy for uterine tumors when comparing different histologies. This study aimed to delineate the primary histology that leads to more favorable outcomes after pulmonary metastasectomy. Methods: The database of the Metastatic Lung Tumor Study Group of Japan for 1984 to 2016 was used to analyze the outcomes of patients with gynecologic malignancies who underwent pulmonary metastasectomy. Prognostic factors and long-term outcomes were compared according to the histology of the primary uterine tumors, specifically adenocarcinoma, squamous cell carcinoma, and sarcoma. The adjusted hazard risks according to disease-free intervals (DFIs) and the number and maximum size of resected tumors were also analyzed to delineate the pattern of risk trends. Results: A total of 319 patients were included in the analysis (122 with adenocarcinomas, 113 with squamous cell carcinomas, 46 with sarcomas, and 38 with other types). The 5-year survival rate was 66.5% for the entire cohort, 71.6% for the patients with adenocarcinoma, 61.3% for those with squamous cell carcinoma, and 55.4% for those with sarcoma. Multivariate analyses identified the positive prognostic factors as DFI ≥12 months in adenocarcinoma and sarcoma and the primary site (corpus) of uterine tumors in adenocarcinoma. The nonlinear adjusted hazard risks indicated that a shorter DFI was associated with an elevated risk of death in patients with adenocarcinoma and sarcoma. Conclusions: The survival outcome after pulmonary metastasectomy varies according to primary tumor histology, and the prognostic factors differ among histologic subtypes. Surgical indications should be determined based on the prognostic factors for each histology.

Survival after Lung Metastasectomy from Esophageal Cancer: Results from a Multi-Institutional Database.

To clarify the clinical impact and to identify prognostic predictors of surgical intervention for pulmonary metastasis from esophageal cancer, a registry database analysis was performed. From January 2000 to March 2020, patients who underwent resection of pulmonary metastases from primary esophageal cancer at 18 institutions were registered in a database developed by the Metastatic Lung Tumor Study Group of Japan. An amount of 109 cases were reviewed and examined for the prognostic factors for pulmonary metastasectomy of metastases from esophageal cancer. As a result, five-year overall survival after pulmonary metastasectomy was 34.4% and five-year disease-free survival was 22.1%. The multivariate analysis for overall survival revealed that initial recurrence site, maximum tumor size, and duration from primary tumor treatment to lung surgery were selected as the significant prognostic factors (p = 0.043, p = 0.048, and p = 0.037, respectively). In addition, from the results of the multivariate analysis for disease free survival, number of lung metastases, initial recurrence site, duration from primary tumor treatment to lung surgery, and preoperative chemotherapy for lung metastasis were selected as the significant prognostic factors (p = 0.037, p = 0.008, p = 0.010, and p = 0.020, respectively). In conclusion, eligible patients with pulmonary metastasis from esophageal cancer selected based on the identified prognostic predictors would be good candidates for pulmonary metastasectomy.

Association of HLA-class II alleles with risk of relapse in myeloperoxidase-antineutrophil cytoplasmic antibody positive vasculitis in the Japanese population.

Background: Disease relapse remains a major problem in the management of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). In European populations, HLA-DPB1*04:01 is associated with both susceptibility and relapse risk in proteinase 3-ANCA positive AAV. In a Japanese population, we previously reported an association between HLA-DRB1*09:01 and DQB1*03:03 with susceptibility to, and DRB1*13:02 with protection from, myeloperoxidase-ANCA positive AAV (MPO-AAV). Subsequently, the association of DQA1*03:02, which is in strong linkage disequilibrium with DRB1*09:01 and DQB1*03:03, with MPO-AAV susceptibility was reported in a Chinese population. However, an association between these alleles and risk of relapse has not yet been reported. Here, we examined whether HLA-class II is associated with the risk of relapse in MPO-AAV. Methods: First, the association of HLA-DQA1*03:02 with susceptibility to MPO-AAV and microscopic polyangiitis (MPA) and its relationship with previously reported DRB1*09:01 and DQB1*03:03 were examined in 440 Japanese patients and 779 healthy controls. Next, the association with risk of relapse was analyzed in 199 MPO-ANCA positive, PR3-ANCA negative patients enrolled in previously reported cohort studies on remission induction therapy. Uncorrected P values (Puncorr) were corrected for multiple comparisons in each analysis using the false discovery rate method. Results: The association of DQA1*03:02 with susceptibility to MPO-AAV and MPA was confirmed in a Japanese population (MPO-AAV: Puncorr=5.8x10-7, odds ratio [OR] 1.74, 95% confidence interval [CI] 1.40-2.16, MPA: Puncorr=1.1x10-5, OR 1.71, 95%CI 1.34-2.17). DQA1*03:02 was in strong linkage disequilibrium with DRB1*09:01 and DQB1*03:03, and the causal allele could not be determined using conditional logistic regression analysis. Relapse-free survival was shorter with nominal significance in carriers of DRB1*09:01 (Puncorr=0.049, Q=0.42, hazard ratio [HR]:1.87), DQA1*03:02 (Puncorr=0.020, Q=0.22, HR:2.11) and DQB1*03:03 (Puncorr=0.043, Q=0.48, HR:1.91) than in non-carriers in the log-rank test. Conversely, serine carriers at position 13 of HLA-DRß1 (HLA-DRß1_13S), including DRB1*13:02 carriers, showed longer relapse-free survival with nominal significance (Puncorr=0.010, Q=0.42, HR:0.31). By combining DQA1*03:02 and HLA-DRß1_13S, a significant difference was detected between groups with the highest and lowest risk for relapse (Puncorr=0.0055, Q=0.033, HR:4.02). Conclusion: HLA-class II is associated not only with susceptibility to MPO-AAV but also with risk of relapse in the Japanese population.

REV7 in Cancer Biology and Management.

DNA repair and cell cycle regulation are potential biological fields to develop molecular targeting therapies for cancer. Human REV7 was originally discovered as a homologous molecule to yeast Rev7, which is involved in DNA damage response and mutagenesis, and as the second homolog of yeast Mad2, involved in the spindle assembly checkpoint. Although REV7 principally functions in the fields of DNA repair and cell cycle regulation, many binding partners of REV7 have been identified using comprehensive analyses in the past decade, and the significance of REV7 is expanding in various other biological fields, such as gene transcription, epigenetics, primordial germ cell survival, neurogenesis, intracellular signaling, and microbial infection. In addition, the clinical significance of REV7 has been demonstrated in studies using human cancer tissues, and investigations in cancer cell lines and animal models have revealed the greater impacts of REV7 in cancer biology, which makes it an attractive target molecule for cancer management. This review focuses on the functions of REV7 in human cancer and discusses the utility of REV7 for cancer management with a summary of the recent development of inhibitors targeting REV7.

The 9-1-1 DNA clamp subunit RAD1 forms specific interactions with clamp loader RAD17, revealing functional implications for binding-protein RHINO.

The RAD9-RAD1-HUS1 complex (9-1-1) is a eukaryotic DNA clamp with a crucial role at checkpoints for DNA damage. The ring-like structure of 9-1-1 is opened for loading onto 5' recessed DNA by the clamp loader RAD17 RFC-like complex (RAD17-RLC), in which the RAD17 subunit is responsible for specificity to 9-1-1. Loading of 9-1-1 is required for activation of the ATR-CHK1 checkpoint pathway and the activation is stimulated by a 9-1-1 interacting protein, RHINO, which interacts with 9-1-1 via a recently identified RAD1-binding motif. This discovery led to the hypothesis that other interacting proteins may contain a RAD1-binding motif as well. Here, we show that vertebrate RAD17 proteins also have a putative RAD1-binding motif in their N-terminal regions, and we report the crystal structure of human 9-1-1 bound to a human RAD17 peptide incorporating the motif at 2.1 Å resolution. Our structure confirms that the N-terminal region of RAD17 binds to the RAD1 subunit of 9-1-1 via specific interactions. Furthermore, we show that the RAD1-binding motif of RHINO disturbs the interaction of the N-terminal region of RAD17 with 9-1-1. Our results provide deeper understanding of how RAD17-RLC specifically recognizes 9-1-1 and imply that RHINO has a functional role in 9-1-1 loading/unloading and checkpoint activation.

A proper sequence of dynamic alignment in transtibial prosthesis: insight through socket reaction moments.

Dynamic alignment in prosthetic fitting is important because it affects the user's stability, kinematics, and kinetics such as socket reaction moments. It is performed by tuning the spatial relationship between the transtibial prosthetic socket and the foot following sequential observational gait analysis in the three anatomical planes. However, the order of planes in which the adjustment should be performed is still unclear. To investigate the appropriate sequence of dynamic alignment adjustment, ten participants with transtibial amputation were asked to walk in different alignment conditions (flexion, extension, adduction, abduction; lateral, medial, anterior, and posterior translation of the socket, and plantarflexion, dorsiflexion, inversion, and eversion of the foot) to measure socket reaction moments in the out-of-planes (e.g., the effect of sagittal alignment on the coronal moment). A significant difference was found only among socket posterior translation, socket flexion, and baseline alignment in the coronal moment (P = 0.02). The results of the current and previous studies suggest that moments in the coronal plane are affected by alignment changes in all three planes, whereas moments in the sagittal plane are affected only by sagittal alignment changes. It is suggested that the procedure of alignment adjustments should be finalized in the coronal plane.

Crystal structure of the sliding DNA clamp from the Gram-positive anaerobic bacterium Clostridioides difficile.

The sliding DNA clamp is a ring-shaped protein that encircles DNA within its central channel. It binds to multiple proteins, such as DNA polymerases and DNA repair enzymes, and stimulates their enzymatic activities, thereby playing a crucial role in cell survival and proliferation. Accordingly, the bacterial clamp DnaN is considered to be a promising target for bacterial infection therapy. In this regard, 3D structures of DnaN from pathogenic bacteria are essential for the development of chemical compounds with antimicrobial activity. Here, the crystal structure of DnaN from a Gram-positive bacterium Clostridioides difficile, a human pathogen causing infectious diarrhoea, has been determined at 2.13 Å resolution. A comparison of the structures of DnaN from other bacteria indicates that the structural features of DnaN in terms of overall organization are essentially conserved within Gram-positive and Gram-negative bacteria. However, DnaN from C. difficile has structural differences in the potential binding pocket for partner proteins, implying a non-conventional interaction with its binding partners. Our findings will provide insight into the development of new therapies for C. difficile infection.

Angulation vs translation of transtibial prosthetic socket: their difference analyzed by socket reaction moments.

BACKGROUND: Previous studies investigated the effects of alignment changes in transtibial prostheses on socket reaction moments. However, the effects of angular and translational alignment changes with equal displacement between the foot and the socket were not directly compared. RESEARCH QUESTIONS: What are the different effects of angular and translational alignment changes in transtibial prostheses? METHODS: Ten individuals with transtibial prostheses participated in the measurement of temporo-spatial parameters, socket reaction moments, and their timings under nine alignment conditions (3° flexion/extension, anterior/posterior translation, 6° adduction/abduction, medial/lateral translation, and baseline). The displacement of the prosthetic feet was set to be equal between the angular and translational changes. RESULTS: No significant changes in walking speed were found. Similar effects were observed in the magnitudes, but not in timing, of the moments under angular and translational changes in the sagittal plane (p < 0.01 for the differences in peak extension moment among anterior translation, baseline, and extension conditions, and in peak flexion moment among anterior translation, baseline, and extension conditions). In the coronal plane, similar effects were found in the magnitudes of the moments in the early stance (p < 0.01 at 5 %, 20 %, and 75 % stance). A significant difference in magnitude was observed in the late stance (p < 0.01 between adduction and medial translation conditions). SIGNIFICANCE: The timing of the socket reaction moment may be different in the sagittal plane, while the magnitudes of the socket reaction moment in the late stance may be different in the coronal plane between the angular and translational alignment changes.

Time to Incurable Recurrence for Patients Treated With Pulmonary Metastasectomy for Colorectal Cancer.

BACKGROUND: Probability of cure is important for patients with lung metastasis who must decide whether to undergo metastasectomy. Although progression-free survival (PFS) is thought to reflect this, it does not include curative effects by repeat metastasectomy. Thus, the authors developed a new indicator, time to incurable recurrence (TTIR), in which only incurable recurrence was set as an event that included death, with incurable recurrence defined as recurrence not treated by definitive local therapy (DLT), recurrence treated by DLT but with PFS maintained less than 2 years, or recurrence followed by re-recurrence. METHODS: This multi-institutional study included 339 patients who underwent lung metastasectomy for colorectal cancer between 1990 and 2008. RESULTS: Among the 339 patients, 191 experienced recurrence, 77 received DLT for recurrence, 38 had a PFS of 2 years or longer after the treatment, and 33 had maintained a PFS at the last follow-up date. The patients had PFS ranging from 39 to 212 months (median, 101 months). The 5-year OS, PFS, and TTIR rates were respectively 63.4%, 42.2%, and 51.9%. The TTIR curve was similar to the OS curve 7 years after the initial metastasectomy. The difference between TTIR and PFS at 7 years was 9.7%, indicating probability of cure by repeat DLT. Multivariable analysis showed different prognostic factors among OS, PFS, and TTIR. CONCLUSION: At the initial metastasectomy, TTIR may reflect probability of a cure, including cure by repeat DLT, and can be used to analyze prognostic factors associated with cure.

Structural basis for molecular interactions on the eukaryotic DNA sliding clamps PCNA and RAD9-RAD1-HUS1.

DNA sliding clamps are widely conserved in all living organisms and play crucial roles in DNA replication and repair. Each DNA sliding clamp is a doughnut-shaped protein with a quaternary structure that encircles the DNA strand and recruits various factors involved in DNA replication and repair, thereby stimulating their biological functions. Eukaryotes have two types of DNA sliding clamp, proliferating cell nuclear antigen (PCNA) and RAD9-RAD1-HUS1 (9-1-1). The homo-trimer PCNA physically interacts with multiple proteins containing a PCNA-interacting protein box and/or AlkB homologue 2 PCNA-interacting motif. The two motifs bind to PCNA by a similar mechanism; in addition, the bound PCNA structure is similar, implying a universality of PCNA interactions. In contrast to PCNA, 9-1-1 is a hetero-trimer composed of RAD9, RAD1 and HUS1 subunits. Although 9-1-1 forms a trimeric ring structure similar to PCNA, the C-terminal extension of the RAD9 is intrinsically unstructured. Based on the structural similarity between PCNA and 9-1-1, the mechanism underlying the interaction of 9-1-1 with its partners was thought to be analogous to that of PCNA. Unexpectedly, however, the recent structure of the 9-1-1 ring bound to a partner has revealed a novel interaction distinct from that of PCNA, potentially providing a new principle for molecular interactions on DNA sliding clamps.