Gain-of-function mutations of c-kit in human gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal tumors in the human digestive tract, but their molecular etiology and cellular origin are unknown. Sequencing of c-kit complementary DNA, which encodes a proto-oncogenic receptor tyrosine kinase (KIT), from five GISTs revealed mutations in the region between the transmembrane and tyrosine kinase domains. All of the corresponding mutant KIT proteins were constitutively activated without the KIT ligand, stem cell factor (SCF). Stable transfection of the mutant c-kit complementary DNAs induced malignant transformation of Ba/F3 murine lymphoid cells, suggesting that the mutations contribute to tumor development. GISTs may originate from the interstitial cells of Cajal (ICCs) because the development of ICCs is dependent on the SCF-KIT interaction and because, like GISTs, these cells express both KIT and CD34.

Improved Gateway binary vectors: high-performance vectors for creation of fusion constructs in transgenic analysis of plants

We made a series of improved Gateway binary vectors (pGWBs) for plant transformation. Fifteen different reporters and tags, sGFP, GUS, LUC, EYFP, ECFP, G3GFP, mRFP, 6xHis, FLAG, 3xHA, 4xMyc, 10xMyc, GST, T7, and TAP, were employed. Some vectors carry the 2x35S-Omega promoter for higher-level expression. The kanamycin- and hygromycin-resistant markers are independently available for each of the 43 types of vectors, thus an additional transformation of once-transformed plants can be carried out easily. Their small size and high-copy number in Escherichia coli make possible easier handling at plasmid preparation and sequencing. Improved pGWBs should be a powerful tool for transgenic research in plants.

Arabidopsis NPL1: a phototropin homolog controlling the chloroplast high-light avoidance response

Chloroplasts relocate their positions in a cell in response to the intensity of incident light, moving to the side wall of the cell to avoid strong light, but gathering at the front face under weak light to maximize light interception. Here, Arabidopsis thaliana mutants defective in the avoidance response were isolated, and the mutated gene was identified as NPL1 (NPH-like 1), a homolog of NPH1 (nonphototropic hypocotyl 1), a blue light receptor used in phototropism. Hence, NPL1 is likely a blue light receptor regulating the avoidance response under strong light.

The DEFECTIVE IN ANTHER DEHISCIENCE gene encodes a novel phospholipase A1 catalyzing the initial step of jasmonic acid biosynthesis, which synchronizes pollen maturation, anther dehiscence, and flower opening in Arabidopsis

The Arabidopsis mutant defective in anther dehiscence1 (dad1) shows defects in anther dehiscence, pollen maturation, and flower opening. The defects were rescued by the exogenous application of jasmonic acid (JA) or linolenic acid, which is consistent with the reduced accumulation of JA in the dad1 flower buds. We identified the DAD1 gene by T-DNA tagging, which is characteristic to a putative N-terminal transit peptide and a conserved motif found in lipase active sites. DAD1 protein expressed in Escherichia coli hydrolyzed phospholipids in an sn-1-specific manner, and DAD1-green fluorescent protein fusion protein expressed in leaf epidermal cells localized predominantly in chloroplasts. These results indicate that the DAD1 protein is a chloroplastic phospholipase A1 that catalyzes the initial step of JA biosynthesis. DAD1 promoter::beta-glucuronidase analysis revealed that the expression of DAD1 is restricted in the stamen filaments. A model is presented in which JA synthesized in the filaments regulates the water transport in stamens and petals.

Characterization of a cDNA encoding a novel DNA-binding protein, SPF1, that recognizes SP8 sequences in the 5' upstream regions of genes coding for sporamin and beta-amylase from sweet potato

We isolated a cDNA encoding a DNA-binding protein, SPF1, of sweet potato that binds to the SP8a (ACTGTGTA) and SP8b (TACTATT) sequences present in the 5' upstream regions of three different genes coding for sporamin and beta-amylase of tuberous roots. SPF1 comprises 549 amino acids and is enriched in both basic and acidic residues. The amino acid sequence of SPF1 shows no significant homology to any known protein sequences, suggesting that it may represent a new class of DNA-binding protein. Binding studies with 35S-labeled SPF1, synthesized in vitro, and synthetic DNA fragments indicated that, although SPF1 binds to both the SP8a and SP8b sequences, it binds much more strongly to SP8a than to SP8b. SPF1 bound to the SP8a sequence as a monomer. The DNA-binding domain of SPF1 was localized within the C-terminal half of this protein, and a 162-amino acid fragment of SPF1 (Met310-Arg472) showed DNA-binding activity with no change in target sequence specificity. This fragment contains a region enriched in basic amino acids adjacent to a highly acidic stretch. A sequence which is highly homologous to a 40-amino acid sequence in the basic region of the DNA-binding domain is duplicated in the N-terminal part of SPF1. The gene coding for SPF1 is present in one or a few copies per haploid genome and the SPF1 mRNA was detected in leaves, stems and tuberous roots of the sweet potato, in addition to petioles. The level of SPF1 mRNA in the petioles decreased when leaf-petiole cuttings were treated with sucrose to induce accumulation of sporamin and beta-amylase mRNAs.

A new method of diagnosing gastric intestinal metaplasia: narrow-band imaging with magnifying endoscopy

BACKGROUND AND STUDY AIMS

With endoscopy, there is a high rate of interobserver variability in the identification of gastric intestinal metaplasia, and the endoscopic findings correlate poorly with the histological findings. Previous studies by our group investigating the use of a narrow-band imaging system with magnifying endoscopy (NBI-ME) in the gastric mucosa suggested that the appearance of a light blue crest (LBC) on the epithelial surface may be a distinctive endoscopic finding associated with the presence of intestinal metaplasia. The aim of the present study was to clarify the value of NBI-ME for diagnosing gastric intestinal metaplasia.

PATIENTS AND METHODS

The LBC was defined as a fine, blue-white line on the crests of the epithelial surface/gyri. To investigate the histology underlying the appearance of LBC, 44 biopsy specimens were obtained from regions containing LBC and 44 from non-LBC mucosa in 34 patients with atrophic gastritis. Three endoscopists then carried out NBI-ME in 107 consecutive patients to validate the diagnostic accuracy of the novel endoscopic technique. The degree of correlation between the LBC grading and the histological parameters of intestinal metaplasia was then assessed.

RESULTS

The LBC grading correlated with cells that were positive for CD10 ( P = 0.0001) and Alcian blue ( P = 0.036). The appearance of LBC correlated with histological evidence of intestinal metaplasia with a sensitivity of 89 % (95 % CI, 83 - 96 %), a specificity of 93 % (95 % CI, 88 - 97 %), a positive predictive value of 91 % (95 % CI, 85 - 96 %), a negative predictive value of 92 % (95 % CI, 87 - 97 %), and an accuracy of 91 % (95 % CI, 88 - 95 %).

CONCLUSIONS

In narrow-band imaging with magnifying endoscopy, observation of a light blue crest on the epithelial surface in the gastric mucosa is a highly accurate sign of the presence of histological intestinal metaplasia.

An AP2-type transcription factor, WRINKLED1, of Arabidopsis thaliana binds to the AW-box sequence conserved among proximal upstream regions of genes involved in fatty acid synthesis

Although an APETALA2 (AP2)-type transcription factor, WRINKLED1 (WRI1), has been shown to be required for accumulation of triacylglycerols (TAGs) in Arabidopsis seeds, its direct target genes have not been established. Overexpression of WRI1 up-regulated a set of genes involved in fatty acid (FA) synthesis in plastids, including genes for a subunit of pyruvate kinase (Pl-PKbeta1), acetyl-CoA carboxylase (BCCP2), acyl carrier protein (ACP1), and ketoacyl-acyl carrier protein synthase (KAS1), while expression of these genes is reduced in mutants with reduced WRI1 expression. Transient expression of LUC reporter genes with the proximal sequences upstream from the ATG codon of Pl-PKbeta1, BCCP2, and KAS1 in protoplasts was activated by co-expression of WRI1, and recombinant WRI1 bound to these upstream sequences in vitro. The seven WRI1 binding sites shared a sequence [CnTnG](n)(7)[CG], where n is any nucleotide designated as the AW-box, and mutations in AW-boxes near the transcription start site and in the 5'-untranslated region of Pl-PKbeta1 abolished activation by WRI1 in protoplasts and expression during seed maturation. Although expression of genes for the synthesis of TAGs and packaging into oil bodies in the endoplasmic reticulum in developing seeds required WRI1, their expression was not up-regulated by WRI1 overexpression. Thus, WRI1 promotes the flow of carbon to oil during seed maturation by directly activating genes involved in FA synthesis and controlling genes for assembly and storage of TAG.

A new approach to chemoembolization therapy for hepatoma using ethiodized oil, cisplatin, and gelatin sponge

This article reports on a new approach to hepatic arterial chemoembolization therapy using ethiodized oil (Lipiodol, Ultra Fluide), cisplatin, and gelatin sponge (Gelfoam, Upjohn, Kalamazoo, MI) for hepatocellular carcinoma (HCC). The anticancer effects of this therapy on 20 patients who underwent subsequent hepatic resection were evaluated mainly by histologic examination. All main tumors were reduced in size following this therapy. It is notable that in 65% of the patients the tumor size was reduced to less than 50% of that before therapy. All the values of serum alpha-fetoprotein (AFP) in the patients who exhibited pretreatment levels exceeding 100 ng/ml dropped by more than 50%, and in 55% of them it fell below 20 ng/ml. The concentration of platinum in the tumor tissue was significantly higher than that in the nontumorous tissue. In 15 of 20 patients (75%), the main nodules were completely necrotic. Thirteen of the patients had daughter nodules and/or small intrahepatic metastases (Group A); nine had tumor emboli in the portal (hepatic) vein (Group B); 17 had intracapsular invasions (Group C); and ten had extracapsular invasions (Group D). The ratios of patients with completely necrotic cancer cells in Group A were nine of 13 (69%); in Group B, seven of nine (78%), in Group C, 11/17 (65%); and in Group D, four of 10 (40%). In eight of the 20 patients (40%) no viable cancer cells were recognized at any foci. Lesions other than those with extracapsular invasion could be considerably eliminated with this form of therapy. It is expected that this method will become the therapy of choice not only for palliative treatment but also for preoperative treatment.

The DEFECTIVE IN ANTHER DEHISCIENCE gene encodes a novel phospholipase A1 catalyzing the initial step of jasmonic acid biosynthesis, which synchronizes pollen maturation, anther dehiscence, and flower opening in Arabidopsis

The Arabidopsis mutant defective in anther dehiscence1 (dad1) shows defects in anther dehiscence, pollen maturation, and flower opening. The defects were rescued by the exogenous application of jasmonic acid (JA) or linolenic acid, which is consistent with the reduced accumulation of JA in the dad1 flower buds. We identified the DAD1 gene by T-DNA tagging, which is characteristic to a putative N-terminal transit peptide and a conserved motif found in lipase active sites. DAD1 protein expressed in Escherichia coli hydrolyzed phospholipids in an sn-1-specific manner, and DAD1-green fluorescent protein fusion protein expressed in leaf epidermal cells localized predominantly in chloroplasts. These results indicate that the DAD1 protein is a chloroplastic phospholipase A1 that catalyzes the initial step of JA biosynthesis. DAD1 promoter::beta-glucuronidase analysis revealed that the expression of DAD1 is restricted in the stamen filaments. A model is presented in which JA synthesized in the filaments regulates the water transport in stamens and petals.

Application of sentinel node biopsy to gastric cancer surgery

BACKGROUND

Sentinel node (SN) biopsy has been tried in the management of a variety of cancers with the hope that it would eliminate many unnecessary lymph node dissections, resulting in less morbidity. This important technique, however, has not been tried in gastric cancer surgery. The feasibility of SN biopsy and its accuracy in predicting the lymph node status in patients with gastric cancer were examined in the current study.

PATIENTS AND METHODS

SN biopsy was performed in patients with T1 (n = 44) or T2 (n = 30) gastric cancers (ie, immediately after laparotomy, indocyanine green was injected around the primary tumor, and the green-stained nodes [SNs: 2.6 +/- 1.7 nodes per patient] were removed). Then, gastrectomy with extended lymphadenectomy was performed. The unstained nodes (non-SNs: 39 +/- 18 nodes per patient) were obtained from the resected specimens. Both SNs and non-SNs were subjected to histologic examination with hematoxylin-eosin.

RESULTS

SNs could be identified in 73 of 74 patients (success rate, 99%). Of these 73 patients, 10 had lymph node metastases in SNs or non-SNs, or both; 6 in both SNs and non-SNs; 3 in SNs alone; and 1 in non-SNs alone. The sensitivity of the SN status in the diagnosis of the lymph node status of the patient was 90% (9/10) and specificity was 100% (63/63). Sensitivity was 100% in the T1 group (n = 44) and 88% in the T2 group (n = 29).

CONCLUSIONS

SN biopsy using indocyanine green can be performed with a high success rate, and the SN status can predict the lymph node status with a high degree of accuracy, especially in patients with T1 gastric cancer.

Treatment of hepatocellular carcinoma by transcatheter arterial embolization combined with intraarterial infusion of a mixture of cisplatin and ethiodized oil

The therapeutic effectiveness of transcatheter arterial embolization (TAE) with intraarterial infusion of cisplatin/ethiodized oil mixture in treatment of resectable and unresectable hepatocellular carcinoma was compared with TAE with intraarterial infusion of doxorubicin mixed with and without ethiodized oil. The series included 97 patients with unresectable hepatocellular carcinoma and 40 patients with resectable hepatocellular carcinoma. With TAE using doxorubicin infusion, a partial response of the tumor was seen in only 11%, and the 2-yr survival was calculated to be only 5%. Histologic examination of the specimens obtained by hepatectomy also showed that this treatment was relatively ineffective in daughter tumor and portal tumor thrombi. In contrast, TAE with infusion of cisplatin/ethiodized oil mixture significantly increased the rate of partial response (38%), and significantly prolonged the 2-yr survival (45%). Histologically this treatment gave severe necrosis in daughter tumors (69%) and tumor thrombi (78%) as well as main tumor (75%). This treatment was significantly better than TAE with doxorubicin and ethiodized oil infusion in terms of the tumor regression and histologic responses of main tumor and portal vein tumor thrombi, but not in terms of the 2-yr survival. However, 2 patients (8%) died within 4 wk of the latter treatment, whereas no deaths were reported after the former treatment. Therefore, TAE combined with intraarterial infusion of cisplatin/ethiodized oil mixture may be a safe and useful treatment modality for hepatocellular carcinoma.

Arabidopsis auxin response factor6 and 8 regulate jasmonic acid biosynthesis and floral organ development via repression of class 1 KNOX genes

Two mutations in Arabidopsis thaliana, auxin response factor6 (arf6) and arf8, concomitantly delayed the elongation of floral organs and subsequently delayed the opening of flower buds. This phenotype is shared with the jasmonic acid (JA)-deficient mutant dad1, and, indeed, the JA level of arf6 arf8 flower buds was decreased. Among JA biosynthetic genes, the expression level of DAD1 (DEFECTIVE IN ANTHER DEHISCENCE1) was markedly decreased in the double mutant, suggesting that ARF6 and ARF8 are required for activation of DAD1 expression. The double mutant arf6 arf8 also showed other developmental defects in flowers, such as aberrant vascular patterning and lack of epidermal cell differentiation in petals. We found that class 1 KNOX genes were expressed ectopically in the developing floral organs of arf6 arf8, and mutations in any of the class 1 KNOX genes (knat2, knat6, bp and hemizygous stm) partially suppressed the defects in the double mutant. Furthermore, ectopic expression of the STM gene caused a phenotype similar to that of arf6 arf8, including the down-regulation of DAD1 expression. These results suggested that most defects in arf6 arf8 are attributable to abnormal expression of class 1 KNOX genes. The expression of AS1 and AS2 was not affected in arf6 arf8 flowers, and as1 and arf6 arf8 additively increased the expression of class 1 KNOX genes. We concluded that ARF6 and ARF8, in parallel with AS1 and AS2, repress the class 1 KNOX genes in developing floral organs to allow progression of the development of these organs.

Endoscopic piecemeal resection with submucosal saline injection of large sessile colorectal polyps

BACKGROUND

Because endoscopic en bloc resection of large, sessile colorectal polyps is technically difficult, they are usually resected piecemeal. However, piecemeal resection makes it difficult to evaluate the completeness of the resection histopathologically. In this study the efficacy of endoscopic piecemeal resection of large, sessile colorectal polyps was investigated after follow-up greater than 1 year.

METHODS

We removed 56 sessile colorectal polyps 2 cm or greater in diameter in 56 patients by using an endoscopic submucosal saline injection technique. Endoscopic examinations were repeated at 3, 6, and 12 months and longer after initial endoscopic resection. If no residual tumor was found endoscopically and histologically, the patient was considered to be "cured."

RESULTS

Of the 56 polyps, 14 (25%) were resected en bloc, and 42 (75%) were resected piecemeal. Of the 42 patients treated with piecemeal resection, 23 (55%) required additional endoscopic or surgical interventions. In patients followed 1 year or longer after initial treatment, the cure rate by en bloc resection was 100% (14 of 14) and that by piecemeal resection was 83% (35 of 42). Arterial bleeding occurred in 4 patients (7%) during or after endoscopic resection. In 3 of them, bleeding was stopped by endoscopic clipping, but 1 patient required emergent laparotomy.

CONCLUSIONS

Endoscopic piecemeal resection after submucosal saline injection with an intensive follow-up program is a safe and effective treatment for large, sessile colorectal polyps.

Inhibition of angiogenesis as a mechanism for inhibition by 1alpha-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3 of colon carcinogenesis induced by azoxymethane in Wistar rats

The effects of 1alpha-hydroxyvitamin D3[1alpha(OH)D3] and 1,25-dihydroxyvitamin D3[1,25(OH)2D3] on the incidence of colon tumors induced by azoxymethane and on the labeling index and angiogenesis of colon tumors were investigated in Wistar rats. Rats received 10 weekly injections of 7.4 mg/kg body weight of azoxymethane and i.p. injections of 1alpha(OH)D3 and 1,25(OH)2D3 at lower and higher doses every other day for 45 weeks. Prolonged administration of both 1alpha(OH)D3 and 1,25(OH)2D3 at a higher dose significantly reduced the incidence of colon tumors in week 45. However, administration of 1alpha(OH)D3 or 1,25(OH)2D3 had little or no effect on the histologic type of colon tumors and cancers. Administration of 1alpha(OH)D3 and 1,25(OH)2D3 at higher doses significantly decreased the labeling index, the immuno-histochemical staining for vascular endothelial growth factor and microvessel counts in colon tumors. Our findings suggest that both 1alpha(OH)D3 and 1,25(OH)2D3 inhibit development of colon tumors. A possible mechanism of inhibition of colon carcinogenesis by 1alpha(OH)D3 and 1,25(OH)2D3 is the inhibition of angiogenesis as well as an anti-proliferative effect.

SHEPHERD is the Arabidopsis GRP94 responsible for the formation of functional CLAVATA proteins

The Arabidopsis shepherd (shd) mutant shows expanded shoot apical meristems (SAM) and floral meristems (FM), disorganized root apical meristems, and defects in pollen tube elongation. We have discovered that SHD encodes an ortholog of GRP94, an ER-resident HSP90-like protein. Since the shd phenotypes in SAM and FM are similar to those of the clavata (clv) mutants, we have explored the possibility that CLV complex members could be SHD targets. The SAM and FM morphology of shd clv double mutants are indistinguishable from those of clv single mutants, and the wuschel (wus) mutation is completely epistatic to the shd mutation, indicating that SHD and CLV act in the same genetic pathway to suppress WUS function. Moreover, the effects of CLV3 overexpression that result in the elimination of SAM activity were abolished in the shd mutant, indicating that CLV function is dependent on SHD function. Therefore, we conclude that the SHD protein is required for the correct folding and/or complex formation of CLV proteins.

RPT2. A signal transducer of the phototropic response in Arabidopsis

The blue light receptor NPH1 (for nonphototropic hypocotyl) has been considered to be the only UV-A/blue light receptor that induces a phototropic response by the hypocotyl and root of Arabidopsis. By analysis of root phototropism (rpt) mutants, we show, however, the involvement of another blue light receptor as well as the existence of two separate signaling pathways working downstream of these receptors in the phototropic response. A newly isolated gene, RPT2, controls one of these pathways. The RPT2 gene is light inducible; encodes a novel protein with putative phosphorylation sites, a nuclear localization signal, a BTB/POZ domain, and a coiled-coil domain; and belongs to a large gene family that includes the recently isolated NPH3 gene. From genetic, physiological, and biochemical evidence, we propose a genetic model of the signaling pathways that induce the phototropic response in Arabidopsis.

MDM2 gene amplification and expression in non-small-cell lung cancer: immunohistochemical expression of its protein is a favourable prognostic marker in patients without p53 protein accumulation

MDM2 is an oncoprotein that inhibits p53 tumour-suppressor protein. Amplification of the MDM2 gene and overexpression of its protein have been observed in some human malignancies, and these abnormalities have a role in tumorigenesis through inactivation of p53 function. To determine the clinicopathological and prognostic value of MDM2 abnormalities in non-small-cell lung cancer (NSCLC), MDM2 gene amplification and its protein expression status were analysed in surgically resected materials. MDM2 gene amplification was detected in only 2 (7%) of the 30 tested patients. MDM2 protein was found immunohistochemically in a total of 48 (24%) of the 201 patients. MDM2 protein was slightly frequently observed in patients with adenocarcinoma, but its presence or absence was not associated with clinicopathological factors such as T-factor, N-factor, stage, tumour size, differentiation or p53 protein status. Overall, MDM2-positive patients tended to have a better prognosis (P = 0.062). In particular, among immunohistochemically p53-negative patients (n = 110), those with positive MDM2 protein expression showed significantly better prognosis (P = 0.039) and, in a multivariate analysis, MDM2 protein status was a favourable prognostic factor (P = 0.037). In contrast, among p53-positive patients (n = 91), there was no difference in prognosis depending on MDM2 protein status. Thus, in the NSCLC patients studied, MDM2 gene amplification was a minor event, but expression of its protein, which was often observed immunohistochemically, was a favourable prognostic marker, especially among patients without p53 protein accumulation. Further study is needed to determine how MDM2 protein expression results in a better prognosis.

Genotypes of canine distemper virus determined by analysis of the hemagglutinin genes of recent isolates from dogs in Japan

Canine distemper of domestic dogs is caused by canine distemper virus (CDV), a member of the morbilliviruses. It has been a highly contagious disease of great veterinary importance for centuries, but for the last several decades it has been controlled satisfactorily by modified live vaccines. In the 1990s, however, it was described that CDV strains genetically different from vaccine strains may have caused the disease in vaccinated dogs. The highest antigenic variation is found in the H protein. Therefore, in the present study, hemagglutinin (H) genes obtained from current vaccines and field isolates and amplified directly from clinical specimens were genetically analyzed by restriction fragment length polymorphism assay and sequencing. Phylogenetic analysis of the H-gene amino acid sequences revealed that at least two CDV genotypes are circulating among dogs in Japan; one is a genotype to which almost all Japanese CDV isolates belong and the other has not been previously described. Both are separate and independent from the other lineages or genotypes of vaccine strains, as well as European and U.S. CDV isolates. The results suggest that CDV has also evolved in Japan, and further studies will be needed for an evaluation and possible improvement of the efficacies of current CDV vaccines.

Regulation of CAPRICE Transcription by MYB Proteins for Root Epidermis Differentiation in Arabidopsis

Epidermal cell differentiation in Arabidopsis root is studied as a model system for understanding cell fate specification. Two types of MYB-related transcription factors are involved in this cell differentiation. One of these, CAPRICE (CPC), encoding an R3-type MYB protein, is a positive regulator of hair cell differentiation and is preferentially transcribed in hairless cells. We analyzed the regulatory mechanism of CPC transcription. Deletion analyses of the CPC promoter revealed that hairless cell-specific transcription of the CPC gene required a 69 bp sequence, and a tandem repeat of this region was sufficient for its expression in epidermis. This region includes two MYB-binding sites, and the epidermis-specific transcription of CPC was abolished when base substitutions were introduced in these sites. We showed by gel mobility shift experiments and by yeast one-hybrid assay that WEREWOLF (WER), which is an R2R3-type MYB protein, directly binds to this region. We showed that WER also binds to the GL2 promoter region, indicating that WER directly regulates CPC and GL2 transcription by binding to their promoter regions.

Cytologic examination of pancreatic juice for differential diagnosis of benign and malignant mucin-producing tumors of the pancreas

BACKGROUND

A new clinical type of pancreatic tumor, the mucin-producing tumor, has been recognized recently. However, it is not always easy to distinguish benign from malignant tumors preoperatively. In this study, three different methods of differentiating mucin-producing tumors of the pancreas were compared.

METHODS

Endoscopic ultrasonography, endoscopic retrograde pancreatography, and cytologic examination of pancreatic juice were performed in 14 patients who had mucin-producing pancreatic tumors (11 carcinomas and 3 adenomas). Pancreatic juice was collected endoscopically without papillotomy.

RESULTS

The sensitivity, specificity, and overall accuracy of endoscopic ultrasonography were 82%, 90%, and 79%, respectively; those of endoscopic retrograde pancreatography were 91%, 91%, and 86%; and those of cytologic examination were 91%, 100%, and 93%.

CONCLUSION

Cytologic examination of pancreatic juice was the best of these three methods for differentiating benign from malignant mucin-producing pancreatic tumors.

Small hepatocellular carcinoma: differentiation from adenomatous hyperplastic nodule with color Doppler flow imaging

Liver nodules smaller than 25 mm in diameter (19 hepatocellular carcinomas [HCCs] and nine adenomatous hyperplastic nodules [AHNs]) were examined with color Doppler flow imaging and hepatic angiography. Angiography revealed a tumor vessel in eight (42%) of the 19 HCCs, while color Doppler flow imaging revealed an arterial pulsating afferent tumor vessel in 10 (53%) of the 19 HCCs but in none of the AHNs. In addition, color Doppler flow imaging revealed a constant-flow efferent tumor vessel continuing to a portal branch in 10 (53%) of the 19 HCCs but in none of the AHNs. In 15 (79%) of the 19 HCCs, a pulsating afferent tumor vessel or a constant-flow efferent tumor vessel or both were observed. Therefore, in this series, color Doppler flow imaging was of value in distinguishing between these two lesions.

The HALTED ROOT gene encoding the 26S proteasome subunit RPT2a is essential for the maintenance of Arabidopsis meristems

In higher plants, post-embryonic development is dependent on the activity of the root and shoot apical meristem (RAM and SAM). The quiescent center (QC) in the RAM and the organizing center (OC) in the SAM are known to be essential for the maintenance of meristematic activity. To understand the mechanism that maintains post-embryonic meristems, we isolated an Arabidopsis mutant, halted root (hlr). In this mutant, the cellular organization was disrupted in post-embryonic meristems both in the root and in the shoot, and their meristematic activity was reduced or became abnormal. We showed that the mutant RAM lost its QC identity after germination, which was specified during embryogenesis, whereas the identity of differentiated tissues was maintained. In the post-embryonic SAM, the expression pattern of a typical OC marker gene, WUSCHEL, was disturbed in the mutant. These observations indicate that the HLR gene is essential to maintain the cellular organization and normal nature of the RAM and SAM. The HLR gene encodes RPT2a, which is a subunit of the 26S proteasome that degrades key proteins in diverse cellular processes. We showed that the HLR gene was expressed both in the RAM and in the SAM, including in the QC and the OC, respectively, and that the activity of proteasomes were reduced in the mutant. We propose that proteasome-dependent programmed proteolysis is required to maintain the meristem integrity both in the shoot and in the root.

Rapidly growing thyroid carcinoma during pregnancy

We experienced two cases of papillary carcinoma of the thyroid during pregnancy. The thyroid carcinomas grew rapidly in early pregnancy. We speculate that human chorionic gonadotropin plays an important role in the rapid growth of thyroid carcinoma during pregnancy.

Early depressed adenocarcinomas of the large intestine

From January 1987 to December 1990, five cases of early depressed cancer of the large intestine were seen. Endoscopically, almost all of these tumors were located in the proximal colon and looked like a reddish depression (similar to the sucker of an octopus). Histologically, all of these cancers were well differentiated and tended to reach deeper layers at an early stage. Four (80%) of these cancers were not associated with adenoma and were thought to have arisen de novo.