Can endoscopic retrograde cholangiopancreatography-related procedures for resolving acute cholangitis be effectively and safely performed in patients with surgically altered anatomy? Comparison study to evaluate the timing of short-type single-balloon enteroscopy-assisted endoscopic retrograde cholangiopancreatography

OBJECTIVES

Balloon enteroscopy (BE)-assisted endoscopic retrograde cholangiopancreatography (ERCP)-related procedures to resolve acute cholangitis (AC) in patients with surgically altered anatomy (SAA) are limited. There is a lack of evidence on whether the timing of BE-assisted ERCP affects clinical outcomes in patients with AC. This study aimed to evaluate the clinical outcomes of short-type single-balloon enteroscopy (short SBE)-assisted ERCP in patients with SAA and AC.

METHODS

Patients with AC who underwent short SBE-assisted ERCP procedures between September 2011 and April 2022 were retrospectively reviewed. The outcomes of procedures undergone at ≤24 h and >24 h were compared. The primary outcome was the length of stay (LOS).

RESULTS

Overall, 56 patients underwent procedures at ≤24 h, and 58 patients at >24 h. The procedural success and adverse event rates of short SBE-assisted ERCP were 87.7% (95% confidence interval [CI] 80.3-93.1%) and 4.4% (95% CI 1.4-9.9%), respectively. Patients with severe (Grade III) AC and systemic inflammatory response syndrome were more in early (at ≤24 h) ERCP groups. LOS and median time from ERCP procedures to discharge were shorter in the early group. Procedural success and adverse event rates between both groups had no significant differences. Multivariable linear regression analysis showed that ERCP performed at ≤24 h was associated with shorter LOS, while severe cholangitis and malignant biliary obstruction were associated with longer LOS.

CONCLUSIONS

Short SBE-assisted ERCP is effective and safe in patients with SAA and AC. Early procedures seemed to attribute early improvement of general condition, thus shortening the LOS.

Endoscopic ultrasound‑guided biliary drainage in patients with surgically altered anatomy: a systematic review and Meta‑analysis

BACKGROUND AND AIMS

Endoscopic retrograde cholangiopancreatography is technically challenging to perform in patients with surgically altered anatomy (SAA). For these patients, endoscopic ultrasound-guided biliary drainage (EUS-BD) is one of the good indications. The aim of our systematic review and meta-analysis was to identify and evaluate evidence of the efficacy and safety of EUS-BD in patients with SAA.

METHODS

A systematic review of the PubMed was conducted through to December 2021 to identify studies performing EUS-BD in patients with SAA. The primary outcome was the pooled technical success proportion in patients with SAA. The pooled clinical success and adverse event proportions in patients with SAA were also analyzed.

RESULTS

The search identified 1195 possible records, with 18 studies meeting our criteria for analysis, reporting data for 409 patients with SAA who underwent EUS-BD. The pooled technical success, clinical success and adverse event proportions in patients with SAA were 97.8% (95% confidence interval [CI], 95.8-99.7%), 94.9% (95% CI, 91.8-98.1%), and 12.8% (95% CI, 7.4-18.1%), respectively.

CONCLUSIONS

EUS-BD is effective for patients with SAA. However, adverse events should be considered when performing EUS-BD in these patients.

Multifunctional chemical inhibitors of the florigen activation complex discovered by structure-based high-throughput screening

Structure-based high-throughput screening of chemical compounds that target protein-protein interactions (PPIs) is a promising technology for gaining insight into how plant development is regulated, leading to many potential agricultural applications. At present, there are no examples of using high-throughput screening to identify chemicals that target plant transcriptional complexes, some of which are responsible for regulating multiple physiological functions. Florigen, a protein encoded by FLOWERING LOCUS T (FT), was initially identified as a molecule that promotes flowering and has since been shown to regulate flowering and other developmental phenomena such as tuber formation in potato (Solanum tuberosum). FT functions as a component of the florigen activation complex (FAC) with a 14-3-3 scaffold protein and FD, a bZIP transcription factor that activates downstream gene expression. Although 14-3-3 is an important component of FAC, little is known about the function of the 14-3-3 protein itself. Here, we report the results of a high-throughput in vitro fluorescence resonance energy transfer (FRET) screening of chemical libraries that enabled us to identify small molecules capable of inhibiting FAC formation. These molecules abrogate the in vitro interaction between the 14-3-3 protein and the OsFD1 peptide, a rice (Oryza sativa) FD, by directly binding to the 14-3-3 protein. Treatment with S4, a specific hit molecule, strongly inhibited FAC activity and flowering in duckweed, tuber formation in potato, and branching in rice in a dose-dependent manner. Our results demonstrate that the high-throughput screening approach based on the three-dimensional structure of PPIs is suitable in plants. In this study, we have proposed good candidate compounds for future modification to obtain inhibitors of florigen-dependent processes through inhibition of FAC formation.

Factors affecting complete stone extraction in the initial procedure in short type single-balloon enteroscopy-assisted endoscopic retrograde cholangiography for patients with Roux-en-Y gastrectomy

OBJECTIVES

This study aimed to evaluate the efficacy and safety of stone extraction in patients who underwent Roux-en-Y gastrectomy using short-type single-balloon enteroscopy (SBE) and to clarify the factors affecting complete stone extraction in the initial procedure.

METHODS

The data of patients with Roux-en-Y gastrectomy who underwent endoscopic stone extraction using short SBE between September 2011 and January 2022 was analyzed.

RESULTS

Overall, 85 patients were scheduled to undergo stone extraction. 77 patients were intended stone extraction after successful biliary cannulation. The complete stone extraction success in the initial procedure, overall complete stone extraction success including repeated procedures, and adverse event rates were 68.2% (95% confidence interval [CI], 57.2%-77.9%), 87.1% (95% CI, 78.0%-93.4%), and 8.2% (95% CI, 3.4%-16.2%), respectively. Multiple logistic regression analysis indicated that bile duct diameter affected the success of complete stone extraction after successful biliary cannulation in the initial procedure (odds ratio 0.53, 95% CI, 0.30-0.94, p = .03).

CONCLUSIONS

Stone extraction in patients with Roux-en-Y gastrectomy using short SBE was effective. Patients with a large diameter bile duct required several sessions for complete stone extraction, suggesting that more dedicated devices are warranted for patients with surgically altered anatomy.

Gel immersion endoscopic submucosal dissection: clinical experience with 13 cases of superficial esophageal cancer

Esophageal endoscopic submucosal dissection (ESD) of tumors located on the gravity side is technically challenging. Given that gel immersion ESD (GIESD) is performed by immersing lesions in gel, we hypothesized that it could be used to eliminate the disadvantage associated with submerging the gravity side. Here, we performed GIESD using VISCOCLEAR for superficial esophageal cancer on the gravity side of the esophagus, with monopolar devices. This study aimed to evaluate the short-term outcomes of GIESD for superficial esophageal cancer. Fifteen patients with 16 superficial esophageal cancers underwent GIESD by a single operator, and 13 cases were evaluated. All patients were male, and GIESD was performed in the middle (12/13, 92.3 %) and lower (1/13, 7.7 %) thoracic esophagus. The lesions were located on the left (7/13, 53.8 %), posterior (5/13, 38.5 %), and right (1/13, 7.7 %) esophageal walls. The median procedure time was 27 minutes (interquartile range [IQR], 14-68), and the median dissection speed was 20 mm ² /min (IQR, 14-25.7). The median amount of gel used was 400 mL (IQR, 360-580), and no gel-related adverse events were observed. The median total dose of midazolam was 3 mg (IQR, 2-5). GIESD was completed with en bloc and R0 resections achieved in 100 % of the 13 cases. Delayed adverse events, such as bleeding or perforation, did not occur (0/13, 0 %).

Effectiveness of a multi-loop traction device for colorectal endoscopic submucosal dissection performed by trainees: a pilot study

Colorectal endoscopic submucosal dissection (ESD) is a difficult procedure, and its introduction to trainees has been debated. Although the criteria for performing colorectal ESD vary among institutions, it is often allowed after gaining experience performing surgeries in animals and upper gastrointestinal ESD. This pilot study aimed to compare the treatment outcomes of ESD performed by trainees using the multi-loop traction device (MLTD group) and those of conventional ESD performed by experts (control group). It also aimed to determine whether the MLTD can be used to safely introduce colorectal ESD to trainees. We included 26 colorectal ESD patients (13 in the MLTD group and 13 in the control group) treated at our hospital from October to December 2021. There were no significant differences in the procedure time (50 min vs. 30 min), dissection speed (19.9 mm²/min vs. 28.7 mm²/min), and intraoperative perforation (0% vs. 0%) of the two groups. Furthermore, the rate of ESD self-completion in the MLTD group was 100%. Therefore, the use of the MLTD allowed the safe introduction of colorectal ESD, even among endoscopists with no experience performing colorectal ESD. Consequently, the use of the MLTD may replace animal and upper gastrointestinal ESD when introducing colorectal ESD to trainees.

Effectiveness of clip-and-thread traction-assisted duodenal endoscopic submucosal dissection: a propensity score-matched study (with video)

BACKGROUND AND AIMS

The indications for endoscopic submucosal dissection (ESD) in superficial nonampullary duodenal epithelial tumors (SNADETs) remain controversial because the procedure is technically challenging. Moreover, the effectiveness of clip-and-thread traction-assisted ESD (TA-ESD) for SNADETs has not been assessed. The aim of the current study was to compare the effectiveness of duodenal TA-ESD and conventional ESD for SNADETs.

METHODS

SNADETs treated with conventional ESD or TA-ESD between April 2017 and March 2021 at Saitama Medical University International Medical Center were evaluated retrospectively.

RESULTS

There were 49 cases of conventional ESD and 32 cases of TA-ESD for SNADETs. Using a propensity score-matched design, we selected 26 pairs of cases with conventional ESD and TA-ESD. In the unmatched cohort, patients treated with TA-ESD were characterized by a higher R0 (no tumor identified at the lateral or vertical margins) resection rate (P = .004), more frequent poor submucosal lifting because of fibrosis (P = .014), and shorter follow-up period (P = .0004) than patients treated with conventional ESD. In the propensity score-matched pairs, patients treated with TA-ESD were characterized by a higher rate of R0 resection (P = .021) and a shorter follow-up period (P = .0061). The findings regarding R0 resection rates were confirmed by multivariate logistic regression models, which found a higher odds ratio (OR) for R0 resection in patients who underwent TA-ESD than in patients who underwent conventional ESD both in the unmatched cohort (OR, 17.0; 95% confidence interval, 1.6-178.8; P = .018) and in the propensity score-matched pairs (OR, 26.7; 95% confidence interval, 1.5-460.2; P = .024).

CONCLUSIONS

Our findings suggest TA-ESD may increase the rate of R0 resection in patients with SNADETs in comparison with conventional ESD.

Endoscopic closure using an over‐the‐scope clip for pancreatobiliary endoscopy‐related large gastrointestinal perforation (with video)

Endoscopic ultrasonography (EUS) and endoscopic retrograde cholangiopancreatography (ERCP) for pancreatobiliary diseases require advanced techniques. We usually use an oblique‐viewing endoscope in such procedures. Sometimes, tumor invasion causes gastrointestinal strictures. Crossing a stricture using an oblique‐viewing endoscope is more difficult than using a forward‐viewing scope. Therefore, the frequency of scope perforation is higher than other endoscopic procedures. Although surgical repair for gastrointestinal perforations caused by endoscopes has been performed, patients with pancreatobiliary diseases are often elderly and in poor general condition; therefore, patients are hesitant to undergo surgical treatments. Recently, the usefulness of over‐the‐scope clipping (OTSC) as a minimally invasive rescue method has also been reported. In this study, we report cases of successful endoscopic closure using OTSC for gastrointestinal perforations caused by endoscopes in ERCP and EUS‐related procedures. After those procedures, all cases showed no abnormalities in blood tests or symptoms, and emergency surgery was successfully avoided. Thus, endoscopic closure using OTSC for pancreatobiliary endoscopy‐related gastrointestinal perforations is safe and effective. However, OTSC requires some expertise. A good assessment of defect size and careful insertion of the scope using OTSC attached to the upper esophagus are needed to avoid clip migration or disinsertion and esophageal tears. Therefore, endoscopic closure using OTSC could be the first choice of treatment for pancreatobiliary endoscopy‐related gastrointestinal perforations. We should be familiar with its indication and perform it carefully and rapidly.

Current Status of Endoscopic Biliary Drainage in Patients with Distal Malignant Biliary Obstruction

Distal malignant biliary obstruction is caused by various malignant diseases that require biliary drainage. In patients with operable situations, preoperative biliary drainage is required to control jaundice and cholangitis until surgery. In view of tract seeding, endoscopic biliary drainage is the first choice. Since neoadjuvant therapies are being developed, the time to surgery is increasing, especially in pancreatic cancer cases. Therefore, it requires long stent patency. Recently, preoperative biliary drainage using self-expandable metal stents has been reported as a useful modality to secure long stent patency. In patients with unresectable distal malignant biliary obstruction, self-expandable metal stent is the first choice for maintaining long stent patency. Although there are many comparison studies between a covered and an uncovered self-expandable metal stent, their use is still controversial. Recently, endoscopic ultrasound-guided biliary drainage has been performed as an alternative treatment. The clinical success and stent patency are favorable. We should take into consideration that both endoscopic retrograde cholangiopancreatography-guided biliary drainage and endoscopic ultrasound-guided biliary drainage have advantages and disadvantages and chose the drainage method depending on the patient’s situation or the expertise of the endoscopist. Here, we discuss the current status of endoscopic biliary drainage in patients with distal malignant biliary obstruction.

A retrospective cohort study of factors influencing long procedure times in colorectal endoscopic submucosal dissection

OBJECTIVE

To evaluate the outcomes and factors influencing colorectal endoscopic submucosal dissection (ESD) with a long procedure time.

MATERIALS AND METHODS

In this single-center, retrospective study, we included 1,100 patients with 1,199 lesions who underwent colorectal ESD between April 2016 and December 2020. ESD was performed using an advanced system knife for lesions >20 mm. An S-O clip was used as the traction device. The long-time group (LP; procedure time >120 min) and normal-time group (NP; procedure time <120 min) were compared.

RESULTS

The procedure times were 166.86 and 44.72 min in the LP and NP groups, respectively. The completion rate was higher in the NP group (96.5% vs. 83.5%, p = .001); the completed lesions were resected en bloc. Multivariate analysis revealed 18.8% and 7.8% of submucosal fibrosis in the LP and NP groups, respectively (odds ratio [OR] = 2.410, p = .026). Compared to the NP group, the LP group presented larger maximum lesion sizes and higher rates of R1 resection, and traction device use. Time to introduction of traction device use was longer in the LP than in the NP group (126.05 vs. 21.72 min; p < .001). Fibrosis tends to occur cecal lesions (OR 2.436, p = .011) and laterally spreading tumor-non-granular-pseudo-depressed (LST-NG-PD) (OR 2.6181, p = .001).

CONCLUSIONS

Lesion size and fibrosis were factors associated with a long procedure time in colonic ESD. For fibrotic lesions (LST-NG-PD and cecal lesions), it is necessary to consider early use of traction devices and advisable to plan a strategy for the use of traction devices.

Intraperitoneal Abscess as a Postoperative Complication of Gastric Endoscopic Submucosal Dissection

We herein report a case of intraperitoneal abscess as a postoperative complication of gastric endoscopic submucosal dissection (ESD). A 70-year-old man who underwent ESD for early gastric cancer sought consultation for abdominal pain on postoperative day 28. Abdominal computed tomography revealed intraperitoneal abscess rupture. He underwent image-guided laparoscopic irrigation. His postoperative course was favorable, and he was discharged after 27 days. Intraoperatively, a white plaque adhering to the gastric wall was surrounded by a large pus volume and suspected to be ESD-associated. We present this case with a literature review of the association between intraperitoneal abscess and ESD.

Novel assays to monitor gene expression and protein-protein interactions in rice using the bioluminescent protein, NanoLuc

Luciferases have been widely utilized as sensitive reporters to monitor gene expression and protein-protein interactions. Compared to firefly luciferase (Fluc), a recently developed luciferase, Nanoluciferase (NanoLuc or Nluc), has several superior properties such as a smaller size and stronger luminescence activity. We compared the reporter properties of Nluc and Fluc in rice (Oryza sativa). In both plant-based two-hybrid and split luc complementation (SLC) assays, Nluc activity was detected with higher sensitivity and specificity than that with Fluc. To apply Nluc to research involving the photoperiodic regulation of flowering, we made a knock-in rice plant in which the Nluc coding region was inserted in-frame with the OsMADS15 gene, a target of the rice florigen Hd3a. Strong Nluc activity in response to Hd3a, and in response to change in day length, was detected in rice protoplasts and in a single shoot apical meristem, respectively. Our results indicate that Nluc assay systems will be powerful tools to monitor gene expression and protein-protein interaction in plant research.

DNA methylation is reconfigured at the onset of reproduction in rice shoot apical meristem

DNA methylation is an epigenetic modification that specifies the basic state of pluripotent stem cells and regulates the developmental transition from stem cells to various cell types. In flowering plants, the shoot apical meristem (SAM) contains a pluripotent stem cell population which generates the aerial part of plants including the germ cells. Under appropriate conditions, the SAM undergoes a developmental transition from a leaf-forming vegetative SAM to an inflorescence- and flower-forming reproductive SAM. While SAM characteristics are largely altered in this transition, the complete picture of DNA methylation remains elusive. Here, by analyzing whole-genome DNA methylation of isolated rice SAMs in the vegetative and reproductive stages, we show that methylation at CHH sites is kept high, particularly at transposable elements (TEs), in the vegetative SAM relative to the differentiated leaf, and increases in the reproductive SAM via the RNA-dependent DNA methylation pathway. We also show that half of the TEs that were highly methylated in gametes had already undergone CHH hypermethylation in the SAM. Our results indicate that changes in DNA methylation begin in the SAM long before germ cell differentiation to protect the genome from harmful TEs.

The shoot apical meristem of flowering plants transitions from forming leaves to floral organs. Here Higo et al. show that DNA methylation of many transposons that are hypermethylated in gametes is established in the SAM before flowering, suggesting it protects against harmful transposition long before germ cell differentiation.

Evaluation of the influence of light-curing units on the degree of conversion in depth of a bulk-fill resin

Background

It is known that bulk-fill have been widely studied and used by dentists in the clinic. However, the use of light-curing units that do not have the ability to adequately light-cure these materials at the appropriate depth can affect their clinical performance. The aim of this study was evaluating the influence of 5 different light curing units (LCUs) on the degree of conversion (DC) of a bulk-fill resin at depths of 0 to 4 mm and determined the effect of using 20s exposure and 40s.

Material and Methods

Cylinders of composite were made in a stainless steel matrix (n=10). The specimens were exposed from the top surface using 5 LCUs: Valo® Cordless (VA); Radii Plus (RA); Emitter.D (EM), Biolux Plus (BI), Woodpecker® (WO). The emission wavelength and the power density was determined. After the photoactivation, the Raman vibrational modes were calculated taking as reference the peaks at 1,601 (aromatic bonds C=C) and 1,640 cm-1 (aliphatic bonds C=C).

Results

The largest difference in DC in 20s, comparing the values obtained in the first and last layer is for BI, with a variation from 61.24% to 53.86%. Comparing the LCUs, the last layer in 40s DC values are 57.40% (BI), 58.21% (WO), 58.97% (VA), 60.90% (RA) and 62.42% (EM). The higher the dose (J/cm²) and the close the λmax is to the maximum CQ absorption length (λmax ~ 470 nm) the better the DC value.

Conclusions

There was a significant difference in the DC values between the LCUs with increasing depth of the bulk-fill increments. Results indicate significant differences in DC among the different LCUs as well as enhanced DC when using 40s exposure compared to 20s. It is suggested that for DC improvement using lower power photoactivator increase the exposure time the exposure time should be 20s to 40s.

Key words:Polymerization, Composite Resins, Raman spectroscopy.

Inheritance of co-edited genes by CRISPR-based targeted nucleotide substitutions in rice

The CRISPR/Cas9 system is a revolutionary genome-editing tool for directed gene editing in various organisms. Cas9 variants can be applied as molecular homing devices when combined with various functional effectors such as transcriptional activators or DNA modification enzymes. Target-AID is a synthetic complex of nuclease deficient Cas9 fused to an activation-induced cytidine deaminase (AID) that enables targeted nucleotide substitution (C to T or G to A). We previously demonstrated that the introduction of desired point mutations into target genes by Target-AID confers herbicide tolerance to rice callus. Inheritance of the introduced mutations, as well as the removal of transgenes, are key issues that must be addressed in order to fully develop Target-AID as a plant breeding technique. Here we report the transmission of such mutations from the callus to regenerants and their progenies, leading to a generation of selectable marker-free (SMF) herbicide tolerant rice plants with simultaneous multiplex nucleotide substitutions. These findings demonstrate that Target-AID can be developed into novel plant breeding technology which enables improvement of multiplex traits at one time in combination with sophisticated targeted base editing with the simplicity and versatility of CRISPR/Cas9 system.

Herbicide tolerance-assisted multiplex targeted nucleotide substitution in rice

Acetolactate synthase (ALS) catalyzes the initial step in the biosynthesis of branched-chain amino acids, and is highly conserved from bacteria to higher plants. ALS is encoded by a single copy gene in rice genome and is a target enzyme of several classes of herbicides. Although ALS mutations conferring herbicide-resistance property to plants are well documented, effect of Imazamox (IMZ) on rice and the mutations in ALS correlated with IMZ tolerance were unclear. In this article, the effect of IMZ on rice calli and seedlings in tissue culture conditions were evaluated. Also, the ALSA96V mutation was confirmed to improve IMZ tolerance of rice calli. Based on these results, ALS-assisted multiplex targeted base editing in rice was demonstrated in combination with Target-AID, a CRISPR/Cas9-cytidine deaminase fusion system [1], [2].

The MET1b gene encoding a maintenance DNA methyltransferase is indispensable for normal development in rice

While Arabidopsis bears only one MET1 gene encoding the DNA methyltransferase that is mainly responsible for maintaining CG methylation after DNA replication, rice carries two MET1 genes, MET1a and MET1b, expressed in actively replicating and dividing cells, and MET1b is more abundantly expressed than is MET1a. A met1a null mutant displayed no overt phenotypes, implying that MET1b must play a major role in the maintenance DNA methylation. Here, we employed two met1b null mutants, generated by homologous recombination-mediated knock-in targeting and insertion of endogenous retrotransposon Tos17. These MET1a/MET1a met1b/met1b homozygotes exhibited abnormal seed phenotypes, which is associated with either viviparous germination or early embryonic lethality. They also displayed decreased levels of DNA methylation at repetitive CentO sequences and at the FIE1 gene locus in the embryos. In addition, independently isolated knock-in-targeted plants, in which the promoterless GUS reporter gene was fused with the endogenous MET1b promoter, showed the reproducible, dosage-dependent, and spatiotemporal expression patterns of GUS. The genotyping analysis of selfed progeny of heterozygous met1a met1b null mutants indicated that weakly active MET1a seems to serve as a genetic backup mechanism in rice met1b gametophytes, although the stochastic and uncoordinated activation of epigenetic backup mechanisms occurred less efficiently in the met1b homozygotes of rice than in the met1 homozygotes of Arabidopsis. Moreover, passive depletion of CG methylation during the postmeiotic DNA replication in the haploid nuclei of the met1a met1b gametophytes in rice results in early embryonic lethality. This situation somewhat resembles that of the met1 gametophytes in Arabidopsis.

Positive-negative-selection-mediated gene targeting in rice

Gene targeting (GT) refers to the designed modification of genomic sequence(s) through homologous recombination (HR). GT is a powerful tool both for the study of gene function and for molecular breeding. However, in transformation of higher plants, non-homologous end joining (NHEJ) occurs overwhelmingly in somatic cells, masking HR-mediated GT. Positive-negative selection (PNS) is an approach for finding HR-mediated GT events because it can eliminate NHEJ effectively by expression of a negative-selection marker gene. In rice-a major crop worldwide-reproducible PNS-mediated GT of endogenous genes has now been successfully achieved. The procedure is based on strong PNS using diphtheria toxin A-fragment as a negative marker, and has succeeded in the directed modification of several endogenous rice genes in various ways. In addition to gene knock-outs and knock-ins, a nucleotide substitution in a target gene was also achieved recently. This review presents a summary of the development of the rice PNS system, highlighting its advantages. Different types of gene modification and gene editing aimed at developing new plant breeding technology based on PNS are discussed.

Gene editing a constitutively active OsRac1 by homologous recombination-based gene targeting induces immune responses in rice

OsRac1 is a member of the plant small GTPase Rac/Rop family and plays a key role in rice immunity. The constitutively active (CA) G19V mutation of OsRac1 was previously shown to induce reactive oxygen species production, phytoalexin synthesis and defense gene activation, leading to resistance to rice blast infection. To study further the effect of the G19V mutation in disease resistance, we introduced a single base substitution by gene targeting and removed the selectable marker using Cre-loxP site-specific recombination. The CA-OsRac1 gene generated by gene targeting was termed CA-gOsRac1. The G19V mutation was transferred from a targeting vector to the OsRac1 locus and stably transmitted to the next generation. In the leaf blade of homozygous CA-gOsRac1 plants, mutant transcript levels were much lower than in those of wild-type plants. In contrast, mutant transcripts in roots, leaf sheaths and panicles were more abundant than those in leaf blades. However, upon chitin treatment, the expression of defense-related genes PAL1 and PBZ1 in the cell culture was greater in the mutants compared with wild-type plants. Furthermore, induction of hypersensitive response (HR)-like cell death was observed in the leaf sheaths of mutant plants infected with a compatible race of rice blast fungus. In the CA-gOsRac1 plants, a number of genes previously shown to be induced by Magnaporthe oryzae and Xanthomonas oryzae pv. oryzae (Xoo) infection were induced in the leaf sheath without pathogen infection. These results suggest that gene targeting will provide mutations useful for gene function studies and crop improvement.

A null mutation of ROS1a for DNA demethylation in rice is not transmittable to progeny

Genes that promote DNA methylation and demethylation in plants have been characterized mainly in Arabidopsis. Arabidopsis DNA demethylation is mediated by bi-functional DNA enzymes with glycosylase activity that removes 5-methylcytosine and lyase activity that nicks double-stranded DNA at an abasic site. Homologous recombination-promoted knock-in targeting of the ROS1a gene, the longest of six putative DNA demethylase genes in the rice genome, by fusing its endogenous promoter to the GUS reporter gene, led to reproducibly disrupted ROS1a in primary (T(0)) transgenic plants in the heterozygous condition. These T(0) plants exhibited no overt morphological phenotypes during the vegetative phase, and GUS staining showed ROS1a expression in pollen, unfertilized ovules and meristematic cells. Interestingly, neither the maternal nor paternal knock-in null allele, ros1a-GUS1, was virtually detected in the progeny; such an intransmittable null mutation is difficult to isolate by conventional mutagenesis techniques that are usually used to identify and isolate mutants in the progeny population. Even in the presence of the wild-type paternal ROS1a allele, the maternal ros1a-GUS1 allele caused failure of early-stage endosperm development, resulting in incomplete embryo development, with embryogenesis producing irregular but viable embryos that failed to complete seed dormancy, implying non-equivalent maternal and paternal contribution of ROS1a in endosperm development. The paternal ros1a-GUS1 allele was not transmitted to progeny, presumably because of a male gametophytic defect(s) prior to fertilization. Thus, ROS1a is indispensable in both male and female gametophytes, and DNA demethylation must plays important roles in both gametophytes.

Targeted disruption of an orthologue of DOMAINS REARRANGED METHYLASE 2, OsDRM2, impairs the growth of rice plants by abnormal DNA methylation

Recent methylome analyses of the entire Arabidopsis thaliana genome using various mutants have provided detailed information about the DNA methylation pattern and its function. However, information about DNA methylation in other plants is limited, partly because of the lack of mutants. To study DNA methylation in rice (Oryza sativa) we applied homologous recombination-mediated gene targeting to generate targeted disruptants of OsDRM2, a rice orthologue of DOMAINS REARRANGED METHYLASE 1 and 2 (DRM1/2), which encode DNA methyltransferases responsible for de novo and non-CG methylation in Arabidopsis. Whereas Arabidopsis drm1 drm2 double mutants showed no morphological alterations, targeted disruptants of rice OsDRM2 displayed pleiotropic developmental phenotypes in both vegetative and reproductive stages, including growth defects, semi-dwarfed stature, reductions in tiller number, delayed heading or no heading, abnormal panicle and spikelet morphology, and complete sterility. In these osdrm2 disruptants, a 13.9% decrease in 5-methylcytosine was observed by HPLC analysis. The CG and non-CG methylation levels were reduced in RIRE7/CRR1 retrotransposons, and in 5S rDNA repeats. Associated transcriptional activation was detected in RIRE7/CRR1. Furthermore, de novo methylation by an RNA-directed DNA methylation (RdDM) process involving transgene-derived exogenous small interfering RNA (siRNA) was deficient in osdrm2-disrupted cells. Impaired growth and abnormal DNA methylation of osdrm2 disruptants were restored by the complementation of wild-type OsDRM2 cDNA. Our results suggest that OsDRM2 is responsible for de novo, CG and non-CG methylation in rice genomic sequences, and that DNA methylation regulated by OsDRM2 is essential for proper rice development in both vegetative and reproductive stages.

Homologous recombination-mediated knock-in targeting of the MET1a gene for a maintenance DNA methyltransferase reproducibly reveals dosage-dependent spatiotemporal gene expression in rice

Although homologous recombination-promoted knock-in targeting to monitor the expression of a gene by fusing a reporter gene with its promoter is routine practice in mice, gene targeting to modify endogenous genes in flowering plants remains in its infancy. In the knock-in targeting, the junction sequence between a reporter gene and an endogenous target promoter can be designed properly, and transgenic plants carrying an identical and desired knock-in allele can be repeatedly obtained. By employing a reproducible gene-targeting procedure with positive-negative selection in rice, we were able to obtain fertile transgenic knock-in plants with the promoterless GUS reporter gene encoding beta-glucuronidase fused with the endogenous promoter of MET1a, one of two rice MET1 genes encoding a maintenance DNA methyltransferase. All of the primary (T(0)) transgenic knock-in plants obtained were found to carry only one copy of GUS, with the anticipated structure in the heterozygous condition, and no ectopic events associated with gene targeting could be detected. We showed the reproducible, dosage-dependent and spatiotemporal expression of GUS in the selfed progenies of independently isolated knock-in targeted plants. The results in knock-in targeted plants contrast sharply with the results in transgenic plants with the MET1a promoter-fused GUS reporter gene integrated randomly in the genome: clear interindividual variation of GUS expression was observed among independently obtained plants bearing the randomly integrated transgenes. As our homologous recombination-mediated gene-targeting strategy with positive-negative selection is, in principle, applicable to modify any endogenous gene, knock-in targeting would facilitate basic and applied plant research.

Alternative splicing of the rice OsMET1 genes encoding maintenance DNA methyltransferase

While the Arabidopsis genome carries one copy of the methyltransferase 1 (MET1) gene for DNA methyltransferase, which is mainly responsible for maintaining CpG methylation, the rice genome bears two copies of the MET1 genes, OsMET1a and OsMET1b. The transcripts of OsMET1b accumulate more abundantly than those of OsMET1a in all of the tissues examined, and both genes actively transcribed at the callus, imbibed embryo, root, meristem, young panicle, anther, pistil, and endosperm, all of which contain actively dividing cells. The OsMET1a transcripts contain two 5'-untranslated exons and alternatively spliced 3'-terminal exons. The alternatively spliced transcripts consist of 14, 15, or 16 exons, and all of them encode a putative protein of 1527 amino acids. While the 3'-terminal exon of OsMET1b is unique, alternative splicing occurs in the 5'-terminal regions, which comprise either exons containing 5'-untranslated regions or an exon bearing the initiation codon. Depending upon alternative usage of 5' exons by alternative splicing, the OsMET1b transcripts comprise 11, 12, 13, or 14 exons, and the former two and the latter two longer transcripts encode putative proteins of 1486 and 1529 amino acids, respectively. Moreover, the 5' splicing patterns of OsMET1b can vary in different tissues. These findings are discussed with respect to the possible regulation of the OsMET1 genes.

Efficient transfer of base changes from a vector to the rice genome by homologous recombination: involvement of heteroduplex formation and mismatch correction

Gene targeting refers to the alteration of a specific DNA sequence in an endogenous gene at its original locus in the genome by homologous recombination. Through a gene-targeting procedure with positive–negative selection, we previously reported the generation of fertile transgenic rice plants with a positive marker inserted into the Adh2 gene by using an Agrobacterium-mediated transformation vector containing the positive marker flanked by two 6-kb homologous segments for recombination. We describe here that base changes within the homologous segments in the vector could be efficiently transferred into the corresponding genomic sequences of rice recombinants. Interestingly, a few sequences from the host genome were flanked by the changed sequences derived from the vector in most of the recombinants. Because a single-stranded T-DNA molecule in Agrobacterium-mediated transformation is imported into the plant nucleus and becomes double-stranded, both single-stranded and double-stranded T-DNA intermediates can serve in gene-targeting processes. Several alternative models, including the occurrence of the mismatch correction of heteroduplex molecules formed between the genomic DNA and either a single-stranded or double-stranded T-DNA intermediate, are compared to explain the observation, and implications for the modification of endogenous genes for functional genomic analysis by gene targeting are discussed.

Gene targeting by homologous recombination as a biotechnological tool for rice functional genomics

The modification of an endogenous gene into a designed sequence by homologous recombination, termed gene targeting (GT), has broad implications for basic and applied research. Rice (Oryza sativa), with a sequenced genome of 389 Mb, is one of the most important crops and a model plant for cereals, and the single-copy gene Waxy on chromosome 6 has been modified with a frequency of 1% per surviving callus by GT using a strong positive-negative selection. Because the strategy is independent of gene-specific selection or screening, it is in principle applicable to any gene. However, a gene in the multigene family or a gene carrying repetitive sequences may preclude efficient homologous recombination-promoted GT due to the occurrence of ectopic recombination. Here, we describe an improved GT procedure whereby we obtained nine independent transformed calli having the alcohol dehydrogenase2 (Adh2) gene modified with a frequency of approximately 2% per surviving callus and subsequently isolated eight fertile transgenic plants without the concomitant occurrence of undesirable ectopic events, even though the rice genome carries four Adh genes, including a newly characterized Adh3 gene, and a copy of highly repetitive retroelements is present adjacent to the Adh2 gene. The results indicate that GT using a strong positive-negative selection can be widely applicable to functional genomics in rice and presumably in other higher plants.

Persistent elevation of serum alanine aminotransferase levels leads to poor survival and hepatocellular carcinoma development in type 1 autoimmune hepatitis

BACKGROUND

Although the prognosis of type 1 autoimmune hepatitis is generally good with immunosuppressive treatment, the disease progresses in some patients despite the treatment. The prognosis may be determined by the clinical course.

AIM

To evaluate the long-term prognosis and assess the predictive factors for a serious event, including the development of hepatocellular carcinoma or death.

METHODS

Sixty-nine patients with type 1 autoimmune hepatitis were prospectively followed up regularly, with a median follow-up period of 96 months (49-201 months).

RESULTS

During the follow-up period, three patients (4%) developed hepatocellular carcinoma, and two of these three patients died. Another patient died of liver failure. The 10-year survival rate was 98%, and the 10-year hepatocellular carcinoma-free rate was 93%. The four patients experiencing a serious event received higher maintenance doses of corticosteroid during their follow-up periods than those did not. However, serum alanine aminotransferase levels during the follow-up period were higher in these four patients than in the others.

CONCLUSIONS

Persistent elevation of serum alanine amniotransferase levels during the follow-up period, rather than factors existing prior to medical treatment is considered to be an important prognostic factor, and it is indicated that poor outcomes may result from the resistance to immunosuppressive treatment.

Clinical characteristics of fulminant-type autoimmune hepatitis: an analysis of eleven cases

BACKGROUND

Although a few adult cases of fulminant-type autoimmune hepatitis have been reported, their clinical features and prognosis have remained uncertain.

AIM

To assess the clinical features and prognosis of patients with fulminant-type autoimmune hepatitis.

METHODS

Eleven patients (10%) diagnosed with fulminant-type autoimmune hepatitis in accordance with the 1999 criteria of the International Autoimmune Hepatitis Group were analysed.

RESULTS

All 11 patients were female, with a median age of 53 years. Five patients survived without liver transplantation, one received a liver transplantation, and five died without liver transplantation. Nine patients (82%) survived for 2 weeks or more following diagnosis, without liver transplantation. Except for the patient receiving a liver transplantation, serum total bilirubin levels measured during the clinical course were significantly higher in non-survivors than in survivors, although the accompanying serum alanine aminotransferase levels measured for the two groups were similar. Most significantly, serum total bilirubin levels in non-survivors worsened during days 8-15, while levels in survivors improved during the same period.

CONCLUSIONS

The short-term prognosis for patients with fulminant-type autoimmune hepatitis may be good. However, patients whose serum total bilirubin levels worsen during days 8-15 should be considered for liver transplantation.

Modification of endogenous natural genes by gene targeting in rice and other higher plants

The capability to modify a genomic sequence into a designed sequence is a powerful tool for biologists and breeders to elucidate the function of an individual gene and its cis-acting elements of multigene families in the genome. Gene targeting refers to the alteration of a specific DNA sequence in an endogenous gene at its original locus in the genome. In higher plants, however, the overwhelming occurrence of the random integration of transgenes by non-homologous end-joining is the main obstacle to develop efficient gene targeting. Two approaches have been undertaken to modify a genomic sequence in higher plants- chimeric RNA/DNA oligonucleotide-directed gene targeting to generate a site-specific base conversion, and homologous recombination-dependent gene targeting to produce either a base change or a gene replacement in a sequence-specific manner. The successful and reproducible targeting of an endogenous gene by homologous recombination, independently of gene-specific selection by employing a strong positive-negative selection, has been demonstrated for the first time in rice, an important staple food and a model plant for other cereal species. This review addresses the current status of targeting of an endogenous natural gene in rice and other higher plants and discusses possible models for Agrobacterium- mediated gene targeting by homologous recombination using a strong positive-negative selection.

A tale of two integrations, transgene and T-DNA: gene targeting by homologous recombination in rice

The first successful and reproducible gene targeting by homologous recombination, without the concomitant occurrence of ectopic events, has been reported. This will be a powerful approach for the characterization of gene function in rice, an important crop and a model for other cereal species. Models have been proposed to explain gene replacement by homologous recombination, including a possible model for Agrobacterium-mediated gene targeting using a strong positive-negative selection.

RecQ helicase enhances homologous recombination in plants

RecQ helicase is a key component in the RecF pathway of Escherichia coli for initiation of homologous recombination. Here, we demonstrate that transient expression of RecQ gene in rice embryogenic cell increases the homologous recombination efficiency as much as 4-fold. Further experiments reveal that this effect is influenced by the RecQ dosage. Stable expression of RecQ in rice dramatically increases the homologous recombination events 20- to 40-fold in leaf tissue from different transgenic lines. This is the first evidence indicating that overexpression of RecQ gene can stimulate homologous recombination in plants.

A large-scale Agrobacterium-mediated transformation procedure with a strong positive-negative selection for gene targeting in rice (Oryza sativa L.)

A large-scale transformation procedure handling an adequate number of stable transformants with highly efficient positive-negative selection is a necessary prerequisite to successful gene targeting by homologous recombination, as the integration of a transgene by somatic homologous recombination in higher plants has been reported to be 10(-3) to 10(-5) compared with random integration by non-homologous end joining. We established an efficient and large-scale Agrobacterium-mediated rice transformation protocol that generated around 10(3) stable transformants routinely from 150 seeds and a strong positive-negative selection procedure that resulted in survivors at 10(-2) using the gene for diphtheria toxin A fragment as a negative marker. The established transformation procedure provides a basis for efficient gene targeting in rice.

Efficient gene targeting by homologous recombination in rice

Modification of genes through homologous recombination, termed gene targeting, is the most direct method to characterize gene function. In higher plants, however, the method is far from a common practice. Here we describe an efficient and reproducible procedure with a strong positive/negative selection for gene targeting in rice, which feeds more than half of the world's population and is an important model plant. About 1% of selected calli and their regenerated fertile plants were heterozygous at the targeted locus, and only one copy of the selective marker used was found at the targeted site in their genomes. The procedure's applicability to other genes will make it feasible to obtain various gene-targeted lines of rice.

Laparoscopic features of primary biliary cirrhosis in AMA-positive and AMA-negative patients

BACKGROUND AND STUDY AIMS

Antimitochondrial antibody (AMA)-negative primary biliary cirrhosis (PBC) has been difficult to diagnose. Laparoscopic features of AMA-negative PBC were evaluated in comparison with those of AMA-positive PBC and autoimmune hepatitis.

PATIENTS AND METHODS

71 patients who fulfilled the diagnostic criteria for PBC were enrolled in the study; 48 were AMA-positive and 23 were AMA-negative. As a disease control, 46 autoimmune hepatitis patients were included. Both the frequency and specificity of each laparoscopic finding were evaluated. A laparoscopic scoring system was introduced, which used, common and uncommon laparoscopic findings, and was evaluated for the diagnosis of AMA-negative PBC.

RESULTS

The characteristic laparoscopic findings for AMA-positive PBC were yellowish-white marking (92 %), dark-brown discoloration (73 %), gentle undulation (67 %), reddish patch (38 %), and yellowish-white nodules (32 %). On the other hand, laparoscopic findings such as trench-like depression, reddish markings, and wide and small depressions were uncommon in PBC compared with autoimmune hepatitis. The frequencies of characteristic and uncommon laparoscopic findings did not differ statistically between AMA-positive and AMA-negative PBC, but were different between AMA-positive or AMA-negative PBC and autoimmune hepatitis. Scores based on common and uncommon laparoscopic findings were 5.5 +/- 1.5 (mean +/- SD) in AMA-positive PBC, 5.6 +/- 2.0 in AMA-negative PBC, and - 0.30 +/- 0.5 in autoimmune hepatitis.

CONCLUSION

The laparoscopic findings in AMA-negative PBC did not differ from those of AMA-positive PBC. A laparoscopic scoring system may be helpful in the diagnosis of AMA-negative PBC.

Evaluation of metastatic potential of gastric tumors by staining for proliferating cell nuclear antigen and chromosome 17 numerical aberrations

BACKGROUND

Aberrations in chromosome 17 are important in carcinogenesis. We recently reported that numerical aberrations in chromosome 17 were associated with tumor progression in gastric cancer. The aim of this study was to determine the biological characteristics of gastric tumor cells with chromosome 17 numerical aberrations.

METHODS

Gastric tumor sections (n = 105) and metastatic lymph nodes (n = 16) were stained simultaneously for PCNA (proliferating cell nuclear antigen) and chromosome 17 centromere. Cancers were classified as follows: Group 1: PCNA(+) and numerical chromosomal aberration(+); Group 2: PCNA(-) and numerical chromosomal aberration(+); Group 3: PCNA(+) and numerical chromosomal aberration(-); and Group 4: PCNA(-) and numerical chromosomal aberration(-).

RESULTS

The frequency of Group 1 cells correlated with lymphatic invasion (P < .0001), lymph node metastasis (P < .0001), and venous invasion (P < .01). The frequency of these cells in gastric lesions was lower than in metastatic lymph nodes (P < .01). Logistic regression analysis identified the depth of invasion followed by the frequency of Group 1 cells were two of the most significant independent factors that could predict lymph node metastasis and lymphatic invasion.

CONCLUSIONS

The frequency of gastric tumor cells positive for PCNA and chromosome 17 numerical aberrations may be an indicator of the metastatic potential of gastric cancers.

Laparoscopic findings in primary sclerosing cholangitis

BACKGROUND AND STUDY AIMS

Primary sclerosing cholangitis (PSC) is a cholestatic disease characterized by segmental narrowing and dilatation of bile ducts. Few studies have been performed on the laparoscopic findings associated with this disease, and the present study was intended to assess the usefulness of laparoscopy for the diagnosis and staging of PSC.

PATIENTS AND METHODS

Six patients were examined by laparoscopy with liver biopsy. Repeated laparoscopy was performed in three patients.

RESULTS

Laparoscopy revealed coarse surface irregularity and discoloration. Surface irregularity was classified into four grades: smooth, shallowly depressed, undulated, and nodular. The affected area showed whitish yellow discoloration. The discolored area was demonstrated as a poorly stained area by intravenous injection of indocyanine green (ICG). Lobular markings became apparent because of the yellow color change in the portal tract, resulting in a leopardskin-like appearance. Lymph-vessel dilatation was seen in advanced stages. Repeated laparoscopy of a patient without treatment demonstrated a progression from a smooth surface to a shallow depression with leopardskin-like markings. On the other hand, the two patients treated with immunosuppressive agents showed improvement of liver swelling and disappearance of the leopardskin-like markings and lymph-vessel dilatation.

CONCLUSIONS

Laparoscopy may provide useful information for the diagnosis and staging of PSC.

Mallory-Weiss syndrome with severe bleeding: treatment by endoscopic ligation

There is no consensus as to the best treatment for Mallory-Weiss tears with severe bleeding. Endoscopic ligation is an inexpensive, readily available, and easily learned technique, in contrast to conventional thermocoagulation or hemoclipping. To evaluate the utility of endoscopic ligation, we performed this technique during emergency endoscopy to treat severe bleeding from Mallory-Weiss tears in four patients in our hospital with continuous active bleeding from Mallory-Weiss tears. The patients were all male with an average age of 40.5 years. Symptoms associated with increased intra-abdominal pressure, including retching and vomiting were reported by all patients. The bleeding points were aspirated and controlled by endoscopic ligation, and complete hemostasis was achieved in all cases. We conclude that endoscopic ligation is easy to perform and may provide an alternative treatment for severe bleeding from Mallory-Weiss tears.

Clinical and histopathological features of colonic stromal tumor in a child

Neoplasms of the colonic submucosa are rare in children. Gastrointestinal stromal tumors (GISTs) are undifferentiated tumors, usually diagnosed by immunohistochemistry. We report a 4-year-old girl with a submucosal GIST of the ascending colon, which was detected by computed tomography. Diagnosis after ileocecal resection was established by histology. In addition, sections were examined immunohistochemically, using antibodies against vimentin, desmin, alpha-smooth muscle actin, S100, neuron-specific enolase, c-kit, and CD34. Hematoxylin and eosin-stained sections showed interlacing fascicles with occasional palisades of epithelioid and spindle cells. The tumor cells were positive for vimentin and CD34. To our knowledge, this is the first reported case of colonic stromal tumor in a child.

Antisense waxy genes with highly active promoters effectively suppress waxy gene expression in transgenic rice

To regulate Waxy (Wx) gene expression by introducing antisense genes, we connected the 2.3 kb Wx cDNA having 450 bp of the Wx first intron in reverse orientation to rice Wx and maize alcohol dehydrogenase1 (Adh1) promoters and used these constructs to transform rice plants. Of 10 independent transgenic lines analysed, four lines showed various degrees of reduction in amylose and WAXY (WX) protein levels in the endosperm. In two transgenic lines, complete absence of amylose was observed which made the seeds opaque white like glutinous rice (amylose-deficient waxy (wx) mutant). In one of the transgenic lines, A1 line, the presence of the antisense Wx gene cosegregated with reduction of amylose content in the endosperm. In the same line, a reduction in the level of endogenous Wx mRNA was observed in immature endosperm. Interestingly, this reduction was observed only with mature spliced transcripts but not with unspliced transcripts. Reduced amylose synthesis was also observed in pollen grains of four transgenic lines. These results suggest that integrated antisense Wx gene caused a reduction in amylose synthesis in endosperms and pollen grains of transgenic rice carrying the antisense Wx cDNA. These results indicate that manipulation of starch and other carbohydrates in rice grain is possible using antisense genes.

Obturator hernia: the usefulness of emergent computed tomography for early diagnosis

The diagnosis of obturator hernia is difficult, and delayed treatment is associated with serious complications. Recently, computed tomography (CT) has been used successfully for establishing a correct diagnosis. We encountered nine cases of obturator hernia from 1988 to 1997. All the patients were elderly women. In six of them, a correct diagnosis was established by emergent CT scan. In two of the remaining cases, diagnosis could not be established because of unavailability of CT, and the other patient was diagnosed correctly based on clinical features, including a positive Howship-Romberg sign. Surgical repair was performed successfully. One patient died postoperatively because of septicemia associated with anastomotic leakage. Our cases indicate that emergent CT scan is useful for the diagnosis of obturator hernia, particularly in elderly patients presenting with ileus of unknown origin.

Higher frequencies of numerical aberrations of chromosome 17 in primary gastric cancers are associated with lymph node metastasis

We investigated the correlation between the frequency of numerical aberrations of chromosome 17 and clinicopathological features of gastric cancer. The copy number of chromosome 17 was examined with fluorescence in-situ hybridization (FISH) in frozen specimens from 100 primary gastric cancers. Chromosomal numerical aberrations were diagnosed as chromosomal loss (single signal) or gain (triple or more signals), in each cell. The frequency of numerical aberrations of chromosome 17 correlated significantly with the depth of invasion (P < 0.01), lymph node metastasis (P < 0.0001), lymphatic invasion (P < 0.001), and venous invasion (P < 0.01). Numerical aberrations of chromosome 17 were associated with lymph node metastasis in 32 early gastric cancers. Multiple regression analysis identified the depth of invasion and numerical aberrations of chromosome 17 as independent significant determinants of lymph node metastasis. Our findings suggest that alterations in chromosome 17 may be linked with tumor progression in primary gastric cancer. Our results also indicate that numerical aberrations of chromosome 17 detected by FISH provide important information about the malignant potential (in particular, lymph node metastasis) of primary gastric cancer.