Re-emission of heavy water vapour from soil to the atmosphere

The re-emission process of tritiated water (HTO) deposited on a soil surface is an important process to assess tritium doses to the general public around nuclear fusion facilities in future. A field experiment using heavy water (HDO) as a substitute for HTO was carried out in the summertime to investigate the re-emission process of HTO from soil to the atmosphere. In the experiment, the time variations of depth profiles of HDO concentrations in soil exposed to HDO vapour and soil mixed with HDO were measured during the re-emission process on the field. The HDO concentrations in soil water in top soil layers of both the exposed and mixed soil rapidly decreased with time during the re-emission. However, the decrease of exposed soil was much greater than that of mixed soil. The re-emission process was analysed using a model including the evaporation of HDO from soil, the exchange between soil HDO and air H2O, and the diffusion of HDO in soil. It was found that the model is applicable to calculating the time variations of detailed depth profiles of HDO concentration in soil water in surface soil layers, using an estimated exchange velocity.

Nuclear BAG-1 expression is a biomarker of poor prognosis in esophageal squamous cell carcinoma

Apoptosis is one of the critical biological factors that correlate with the biological behavior of malignant tumors including cancer progression and clinical outcome. The present study was performed to clarify the clinical implications of BAG-1, a bcl-2 binding protein in esophageal squamous cell carcinoma (ESCC). Seventy-one cases with ESCC were investigated. Immunohistochemical study of BAG-1 was performed on resected specimens. The expression pattern of BAG-1 in nuclei and/or cytoplasm was analyzed and correlated with TNM classification, vessel invasion, survival period after surgery. BAG-1 expression in the nuclei was related to the depth of tumor invasion (P = 0.0381) but not to any other clinicopathologic parameters. The cytoplasmic staining pattern of BAG-1 exhibited no correlation with clinicopathologic parameters. Univariate analysis (P < 0.05), but not multivariate analysis, revealed significantly poor prognosis for ESCC cases exhibiting positive nucleic staining for BAG-1. Our data suggests that BAG-1 expression in the nuclei of ESCC plays an important role in tumor development and may be useful for predicting the prognosis after surgery.

Synthesis of 6-(2-thienyl)purine nucleoside derivatives toward the expansion of the genetic code

Unnatural bases specifically pairing with pyridin-2-one, 2-amino-6-(2-thienyl) purine and 2-amino-6-(2-furanyl)purine, were newly designed to replace 2-amino-6-(N,N-dimethylamino)purine. It was expected that these novel purine analogues, as compared with 2-amino-6-(N,N-dimethylamino)purine, might reduce the interference in the stacking interactions with the neighboring bases in a duplex and improve the efficiency of the enzymatic incorporation of the nucleoside triphosphate of pyridin-2-one opposite these unnatural bases. The syntheses of these nucleoside derivatives and the DNA fragments were examined.

Identification of Thermus thermophilus HB8 tRNA (Gm18) methyltransferase gene

For the purpose of identification of the gene for Thermus thermophilus tRNA (Gm18) methyltransferase [tRNA (guanosine-2'-)-methyltransferase, EC 2.1.1.34], the purified enzyme from native source was analyzed by the peptide-mass mapping. The target gene encoded the amino acid sequences of the obtained peptides was searched in data from Thermus thermophilus HB8 genome-sequencing project. We found the target gene AB05130, which was expected to encode a protein composed of 194 amino acid residues and the molecular mass of this protein was calculated as 22083. The recombinant protein was expressed in E. coli as an active form. The Gm18 formation activity of the purified recombinant protein was confirmed by in vitro methylation followed by two-dimensional thin layer chromatography and Liquid Chromatography/Mass Spectrum analysis of substrate tRNA.

Unnatural base pairs between 2-amino-6-(2-thienyl)purine and the complementary bases

The unnatural base, 2-amino-6-(2-thienyl)purine (designated as s), instead of 2-amino-6-(N,N-dimethylamino)purine (designated as x), was designed in order to improve the specificity and efficiency of the base pairing with pyridin-2-one (designated as y). DNA fragments containing s were chemically synthesized, and the thermal stability and the enzymatic reactions involving the s-y pairing were examined. Thermal denaturation experiments showed that the DNA duplex (12-mer) containing the s-y pair was more stable than that containing the x-y pair. The incorporation of dyTP was also more advantageous to the s-y pairing than the x-y pairing in single-nucleotide insertion experiments using the Klenow fragment of Escherichia coli DNA polymerase I.

Small cell carcinoma of the esophagus; clinicopathological and immunohistochemical analysis of six cases

Small cell carcinoma arising in the esophagus is a relatively rare disease. In the more common small cell carcinoma of the lung, the diagnostic significance of several new markers has been recently reported. This study used immunohistochemical techniques in addition to clinicopathological analysis, in order to clarify the utility of newer markers as biological parameters or as diagnostic tools. Six patients with small cell carcinoma of the esophagus were clinicopathologically analyzed. Immunohistochemical staining was performed using primary antibodies for bombesin, CD56 and CD57 in addition to conventional endocrine markers chromogranin A, neuron specific enolase and synaptophysin. All patients died within 2 years of surgery due to cancer recurrence, whether or not they had received adjuvant therapy. Pathological stages ranged from IIa to IVb and lymph node metastasis was observed in five cases. Of the six cases, four showed a positive reaction for bombesin and five were positive for CD57. In contrast, no cases revealed a positive reaction for CD56. The one case to survive 24 months after surgery was not shown to express bombesin, CD56 or CD57. Small cell carcinoma of the esophagus demonstrated an unfavorable prognosis. The study suggested that in this disease, bombesin and CD57 (but not CD56) were useful as biological markers, predicting clinical outcome rather than having diagnostic significance.

Efforts toward creating unnatural base pairs for an expanded genetic code

A series of unnatural base pairs was designed and examined for the expansion of the genetic alphabet and for a better understanding of the mechanism of nucleic acid biosyntheses. To improve the shape complementarity of the previously developed unnatural base pairs, 2-amino-6-(N,N-dimethylamino)purine (x)--pyridon-2-one (y) and 2-amino-6-(2-thienyl)purine (s)--y, the pyrimidine analogue, y, was replaced by a five-member ring, 4-imidazolin-2-one (z), and the s-z pairing in replication was examined. Unnatural bases based on the five-member ring were also applied to the development of non-hydrogen-bonded base pairs.

Photo-regulation of RNA polymerase reaction by use of modified DNA carrying an azobenzene

Transcription reaction by T7-RNA polymerase was photo-regulated on the basis of two strategies as depicted in Scheme 1. It was found that incorporation reaction of azobenzene-tethered uridine triphosphate proceeded only when azobenzene took trans-form (Scheme 1(A)). On the other hand, the transcription was more efficient when the azobenzene moiety, tethered to the non-template strand of the promoter DNA, was in its cis-form under UV irradiation (Scheme 1(B)). Thus, azobenzene-tethered DNAs are promising for the photo-regulation of gene-expression.

Status of NAT screening for HCV, HIV and HBV: experience in Japan

The first nationwide nucleic acid amplification testing (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) of voluntarily donated blood after serological pre-screening and before release of cellular components and plasma for fractionation was implemented by the Japanese Red Cross Blood Transfusion Services. The NAT screening assay using multiplex reagent is time-saving, cost effective, and labour-saving procedure for all blood and blood products including short-shelf life platelets. During the 50-mini-pool NAT screening of serologically negative donations (February 1, 2001-April 30, 2001), we were able to screen out 112 HBV-positive, 25 HCV-positive, and 4 HIV-1 positive units from blood and blood components.

Amplification, up-regulation and over-expression of DVL-1, the human counterpart of the Drosophila disheveled gene, in primary breast cancers

Wnt proteins form a family of highly conserved, secreted signaling molecules that regulate cell-to-cell interactions during embryogenesis. Wnt genes and Wnt signaling are also implicated in cancer. It has been shown that Wnt proteins bind to receptors of the frizzled family on the cell surface. Through several cytoplasmic relay components including DVL-1, the human counterpart of the Drosophila disheveled gene, the signal is transduced to beta-catenin, which then enters the nucleus and forms a complex with T-cell factor (TCF) to activate transcription of Wnt target genes. We describe here the amplification of DVL-1 in 13 of 24 primary breast cancers examined, and increased expression of this gene in 11 of those tumors in comparison to corresponding non-cancerous breast tissues. Immunohistochemical staining demonstrated that DVL-1 protein was prominent in the cytoplasm of cancer cells, but not in normal epithelial cells of the mammary duct or in myoepithelial cells. These data indicate that amplification and increased expression of the DVL-1 gene may play some role in human breast carcinogenesis through derangement of the Wnt signaling pathway.

[Combined operation for left ventricular aneurysm and ventricular septal perforation with normal coronary arteries; report of a case]

We experienced a rare case of left ventricular aneurysm (LVA) and ventricular septal perforation (VSP) with normal coronary arteries, and had a good outcome by undergoing Dor procedure and direct closure of VSP individually. A 68-year-old female was printed out cardiac systolic murmur. Echocardiogram revealed LVA and VSP, but coronary arteriogram showed no significant stenosis. The apex was incised longitudinally, lateral and parallel to the interventricular groove. VSP was directly closed by 2 pieces of 3-0 polypropylene suture with felt strip. Purse-string stitch with 3-0 polyester suture around the transitional zone between fibrotic tissue and viable tissue was secured to firm fibrous tissue. The residual orifice was closed with an elliptical composite patch of equine pericardial patch and polyester velour with 3-0 polypropylene suture. We considered based on the operative finding that myocardial infarction (MI) led to LVA and VSP. Coronary thrombosis rather than coronary spasm may have provoked MI because spasm provocative test was negative.

[Bilateral coronary ostial stenoses with aortic regurgitation in a patient with syphilitic aortitis]

Syphilitic aortitis is now rare in developed countries and is sometimes overlooked. A 61-year-old man with bilateral coronary ostial stenoses (#5:90%, #1:99%) and Sellers III/IV aortic regugitatioin (AR) induced by syphilitic aortitis presented with chest pain. Preoperative rapid plasma reagin titer and Treponema pallidum hemagglutination test were strongly positive, 256 fold and 191.25 C.O.I., respectively. Aortic valve replacement (AVR) and coronary artery bypass grafting (CABG) with bilateral internal thoracic arteries (ITA) was performed successfully. The angiographic features as follows: 1) coronary artery stenosis is generally limited to the ostia, 2) the grade of stenosis is almost always more than 90%, 3) AR is frequently associated with coronary ostial stenosis. CABG should be performed with ITA, not saphenous vein grafts, to avoid occlusion of the ostium of the saphenous vein graft by syphilitic aortitis. Retrograde cardioplegia should be performed if ostial stenosis is severe.

The expression of PDGF, its receptors and capillary morphometry in the developing lung: quantitative studies

The aim of the present study was the evaluation of the expression levels of PDGF-A and B, and PDGFR-alpha, andchanges of capillary cross-sectional areas during terminal vascular network formation in the developing lung. Pathogen-free fetuses and newborns used for rats were used. Lungs were processed for frozen section immunohistochemical staining and parallel tissue specimens were prepared for transmission electron microscopy. The expression levels of PDGF-A and B, and PDGFR-alpha were obtained using quantitative image analysis. Additionally. the morphometry of capillary cross-sectional area was performed. We found that the expression levels of the studied antigens fluctuated, and the highest values were found in21-day old fetuses (p < 0.0001). Although there were no significant differences of the area of "a single" capillary, the area of the endothelium decreased significantly in perinatal period (p <0.0001). We conclude that the statistically significant changes of the studied antigens' expression as well as the of capillary cross-sectional area occur in the perinatal period,

[Surgical repair of left ventricular free wall rupture using layered fibrin glue sheet and fibrin glue; report of a case]

A 57-year-old man with acute myocardial infarction (#13:90%, #6-#8:75%) was admitted to our hospital after the administration of tissue plasminogen activator. Three hours' after emergent percutaneous transluminal coronary angioplasty, he developed left ventricular free wall rupture in the left circumflex artery area. After bleeding was completely controlled by aortic cross clamping, a three-layered of fibrin glue sheet (TachoComb) with fibrin glue was extensively applied to the ruptured site including the infarcted area. He was discharged on the 25th postoperative day and underwent coronary artery bypass grafting to the left anterior descending artery three weeks later. This experience suggests that the layered TachoComb and fibrin glue are effective for left ventricular free wall rupture.

Gastrointestinal stromal tumor of the duodenal ampulla: report of a case

We report herein the case of a 77-year-old woman with a gastrointestinal stromal tumor (GIST) of the duodenal ampulla. The tumor, which was removed by pancreatoduodenectomy due to its malignant potential, showed expansive growth in the muscular coat of the duodenal ampulla. Histologically, the tumor cells were spindle-shaped or round, and exhibited fascicular or storiform growth pattern with frequent mitotic figures. The immunohistochemical and ultrastructural results suggested that the tumor may have originated from the interstitial cells of Cajal in the muscular coat of the duodenal ampulla. To our knowledge, this is the first case of malignant GIST of the duodenal ampulla to be reported in Japan.

The first large-scale nucleic acid amplification testing (NAT) of donated blood using multiplex reagent for simultaneous detection of HBV, HCV, and HIV-1 and significance of NAT for HBV

The first nationwide nucleic acid amplification testing (NAT) for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus type 1 (HIV-1) of voluntarily donated blood after serological pre-screening and before release of cellular components and plasma for fractionation was implemented by the Japanese Red Cross Blood Transfusion Services. From February 1, 2000 to April 30, 2001, specimens from 6,805,010 units of serologically negative donation were screened in minipools of 50 samples within 24 hr after blood donation by NAT using multiplex HBV/HCV/HIV-1 reagent for blood transfusion including short shelf-life platelets. Among them, 112 HBV DNA-positives, 25 HCV RNA positives and 4 HIV-1 RNA positives were screened out and we could prevent transfusion of these NAT positive units. Subtypes/genotypes of HBV DNA, adr/C, adw/A, adw/B, adw/C, ayr/C and ayw/D were found and adr/C was predominant. A total of 61.6 % of them (69/112) were negative by overnight EIA. Sixth three of HBV NAT-positive samples carried virus loads less than 10(4) copies/mL and 92.1 % of them (58/63) were negative by overnight EIA. The virus growth curves of HBV in 6 cases obtained by retrospective and prospective follow-up study showed exponential straight lines in the early stage of serological window periods and the log times of HBV growth (10 fold increase) in serological window period were between 4.6 and 7.6 days. NAT screening with highly sensitive reagents in pool of specimens is useful to exclude blood units with low level of HBV and HBV mutants from blood transfusion.

Transacylation rates of aminoacyladenosine moiety at the 3'-terminus of aminoacyl-transfer ribonucleic acid

The rates of migration of the aminoacyl group (transacylation) between 2'-O-(aminoacyl)-tRNA and 3'-O-(aminoacyl)-tRNA were studied by the nuclear magnetic resonance (NMR) analyses of 3'-terminal fragment models, with regard to the significance of transacylation in the process of protein biosynthesis. 2'(3')-O-L-Alanyladenosine, -valyladenosine, -isoleucyladenosine, -phenylalanyladenosine, and -methionyladenosine, and 2'(3')-O-L-phenylalanyladenosine 5'-phosphate and methionyladenosine 5'-phosphate were chemically synthesized, and the rates of transacylation in deuterated buffer were directly measured by the NMR saturation transfer method. The dependences of transacylation rates on p2H and temperature were analyzed. The results indicate that the transacylation rates are significantly affected by the ionization states of the alpha-amino group of the amino acid moiety but not by the presence of the 5'-phosphate group of the adenylate moiety. The second-order rate constants for the base-catalyzed transacylation reactions were also determined for the ionized form (with alpha-N2H3+ group) of (aminoacyl)adenosines. The transacylation rates of (aminoacyl)adenosines in 1H2O solution at p1H 7.3 and 37 degrees C (intracellular environment) were evaluated as 3-11 s-1 for the 2' leads to 3' transacylation and 1-4 s-1 for the 3' leads to 2' transacylation, indicating that the transacylation rate of free aminoacyl-tRNA is slower than the overall rate of polypeptide chain elongation per ribosome. This suggests the presence of some enzymatic factor for enhancing the transacylation rates of aminoacyl-tRNAs in the polypeptide chain elongation process in vivo.

Preferential transcription of a gene for alpha amylase in the carcinoid tumor of African rodent Mastomys natalensis

The carcinoid tumor in Mastomys natalensis provides a useful animal model of tumorigenesis. We investigated preferentially transcribed genes in this carcinoid tumor by differential hybridization. Fourteen clones corresponding to high levels of transcription were isolated from a cDNA library. Sequencing analysis and a homology search revealed that the clones corresponded to genes for chromogranin and alpha-amylase. High-level transcription of a gene for alpha-amylase gene in Mastomys carcinoid tumor was confirmed by Northern blotting analysis. Furthermore, Western blotting analysis confirmed the expression of alpha-amylase in tumors at the protein level. Immunohistochemical staining revealed alpha-amylase in the cytoplasm of Mastomys carcinoid tumors. Our results demonstrated that an exocrine enzyme 'amylase' could be produced ectopically by a neuroen docrine tumor.

Adenosquamous carcinoma of the pancreas: successful treatment with extended radical surgery, intraoperative radiation therapy, and locoregional chemotherapy

BACKGROUND

Adenosquamous carcinoma of the pancreas is a rare tumor with an extremely poor survival rate. No obvious evidence that multidisciplinary treatments improves the prognosis and survival has been reported.

PATIENT AND RESULTS

A 63-yr-old female with adenosquamous carcinoma of the pancreas underwent extended radical surgery, intraoperative radiation therapy, postoperative intraarterial chemotherapy, and external beam radiation therapy. The patient is alive at 40 mo after surgery with no recurrence.

CONCLUSIONS

Multidisciplinary treatments including aggressive surgery, intraoperative radiation therapy, and locoregional chemotherapy might improve the survival of patients with adenosquamous carcinoma of the pancreas to inhibit liver metastasis and local recurrence.

[A case of elderly in shock due to ruptured stanford type A acute aortic dissection with cardiac tamponade]

An 87-year-old female in shock was referred to our hospital. Emergency chest computed tomography and echocardiography showed a dissecting aneurysm of the ascending aorta and remarkable epicardial effusion. She was diagnosed as having rupture of Stanford type A acute aortic dissection with cardiac tamponade and an emergency operation was performed. While anesthesia was administered, cardiac arrest occurred and the chest was opened. We managed to establish an extra-corporeal circulation and performed graft replacement of the ascending aorta with GRF glue. The patient followed a satisfactory postoperative course and was discharged from the hospital at the 48th postoperative day. The proper indication for operation and minimally invasive procedure enabled us to operate on the elderly patient.

Active taurocholic acid flux through hepatoma cells increases the cellular pool of unesterified cholesterol derived from lipoproteins

The effect of bile acid flux on the fate of lipoprotein-derived cholesterol was studied in bile acid-transporting McNtcp.18 hepatoma cells. The intracellular unesterified cholesterol (UC) concentration rose when McNtcp.18 cells grown in the presence of either high density lipoproteins (HDL) or low density lipoproteins (LDL) were incubated with taurocholic acid (TCA). This effect was more pronounced when the exogenous source of cholesterol was HDL. The presence of TCA in the culture medium of McNtcp.18 cells had no discernible effect on the uptake of cholesteryl esters (CE) from either lipoprotein. TCA treatment of cells preincubated with either lipoprotein did not affect cholesterol synthesis but antagonized the stimulation of cholesterol esterification in cells that were incubated with LDL. The CE concentration in cells treated with TCA was decreased, relative to cells not incubated with TCA, suggesting that cellular CE stores were also hydrolyzed. The TCA treatment reduced the amount of total cholesterol released into the medium by the lipoprotein-treated cells, which was coincident with the reduction in the amount of apolipoprotein B in the culture medium. However, the proportion of UC released into the medium by the lipoprotein-treated cells was increased in cells capable of active bile acid transport. The results indicate that active bile acid flux through hepatoma cells increases the cellular pool of UC derived from lipoproteins. The UC released by the cells into the culture medium under this condition may represent cholesterol destined for direct biliary secretion.

Postoperative evaluation of pylorus-preserving procedures compared with conventional distal gastrectomy for early gastric cancer

We evaluated postoperative function in 98 patients who underwent surgery for early gastric cancer between 1995 and 1998 to compare the results of pylorus-preserving procedures to those of conventional distal gastrectomy with Billroth I (B-I). The pylorus-preserving procedures included endoscopic mucosal resection (EMR), performed in 12 patients; local resection (Local), performed in 14 patients; segmental resection (Seg), performed in 8 patients; and pylorus-preserving gastrectomy (PPG), performed in 19 patients. B-I was performed in 45 patients. The nutritional status and serum albumin (Alb) levels after PPG, the hemoglobin (Hb) levels after EMR, Local, and PPG, and the present/preoperative body weight ratios after EMR, Local, Seg, and PPG were superior to those after B-I. The time before oral intake was recommenced after EMR and Local, the volume of oral intake tolerated after EMR, Local, Seg, and PPG, and the postoperative hospital stay after EMR were all superior to those after B-I. Moreover, significantly fewer patients suffered reflux symptoms after EMR, Local, and PPG, abdominal fullness after EMR, and early dumping syndrome after EMR, Local, and PPG than after B-I. There was also less evidence of gastritis after EMR, Local, and PPG, and of bile reflux after EMR, Local, and PPG, than after B-I. These findings indicate that pylorus-preserving procedures may result in a better postoperative quality of life for selected patients with early gastric cancer.

Immunohistochemical and clinicopathologic analysis of response to neoadjuvant therapy for esophageal squamous cell carcinoma

Recently, neoadjuvant chemotherapy combined with radiation (NAT) has been used in the active treatment of progressive esophageal cancer (T4). However, many patients are resistant to supplemental therapy, and it is necessary to to be aware that side-effects may occur. Accordingly, to minimize adverse reactions and cost, it is important to determine the indications for NAT. We investigated 34 patients with T4 esophageal squamous cell carcinoma and examined the relation between the effects of NAT and immunohistochemical or additional clinicopathologic factors. There was no relation between clinicopathologic factors and immunohistochemical findings (p53 or hsp27 expression), and no clinicopathologic factors showed a relation to a supplemental therapeutic effect. In addition, there was no correlation between p53 staining and therapeutic effects (P=0.734). In contrast, there was a correlation (P=0.0058) between hsp27 staining and therapeutic effect. In conclusion, the usefulness of hsp27 immunostaining in predicting the therapeutic effect of NAT was confirmed in T4 esophageal squamous cell carcinoma.

Vegetative pyoderma gangrenosum in chronic renal failure

We report the case of a 58-year-old woman with painful recurrent erythematous lesions on both legs of 6 months' duration. The patient had been treated with haemodialysis for chronic renal failure for the previous 10 years. Physical examination revealed pea-sized erythematous nodules with sinus formation and discharge of bloody pus, which yielded neither bacterial nor fungal cells in culture. These lesions healed leaving cribriform scars, after bed rest, topical disinfection and systemic and in some areas intralesional corticosteroids. Cases of pyoderma gangrenosum are usually classified as one of four clinical variants: ulcerative, pustular, bullous and vegetative. Our case might correspond to a vegetative form in view of the development of sinuses, neutrophilic abscesses and palisading granuloma, even though no ulceration was observed.

Structural basis for the recognition of isoleucyl-adenylate and an antibiotic, mupirocin, by isoleucyl-tRNA synthetase

An analogue of isoleucyl-adenylate (Ile-AMS) potently inhibits the isoleucyl-tRNA synthetases (IleRSs) from the three primary kingdoms, whereas the antibiotic mupirocin inhibits only the eubacterial and archaeal IleRSs, but not the eukaryotic enzymes, and therefore is clinically used against methicillin-resistant Staphylococcus aureus. We determined the crystal structures of the IleRS from the thermophilic eubacterium, Thermus thermophilus, in complexes with Ile-AMS and mupirocin at 3.0- and 2.5-A resolutions, respectively. A structural comparison of the IleRS.Ile-AMS complex with the adenylate complexes of other aminoacyl-tRNA synthetases revealed the common recognition mode of aminoacyl-adenylate by the class I aminoacyl-tRNA synthetases. The Ile-AMS and mupirocin, which have significantly different chemical structures, are recognized by many of the same amino acid residues of the IleRS, suggesting that the antibiotic inhibits the enzymatic activity by blocking the binding site of the high energy intermediate, Ile-AMP. In contrast, the two amino acid residues that concomitantly recognize Ile-AMS and mupirocin are different between the eubacterial/archaeal IleRSs and the eukaryotic IleRSs. Mutagenic analyses revealed that the replacement of the two residues significantly changed the sensitivity to mupirocin.

Enhanced invasiveness of pancreatic adenocarcinoma cells stably transfected with cationic trypsinogen cDNA

Various studies have described increased expression of cationic trypsinogen in malignant tumor cells. To explore the role of secreted cationic trypsinogen in invasion by cancer cells, we introduced cationic trypsinogen cDNA into Panc-1, a pancreatic adenocarcinoma-derived cell line that lacks expression of endogeneous trypsinogen. Four independent clones (designated Panc-1-Try-7, -9, -11 and -24) stably expressing cationic trypsinogen mRNA were isolated and processed for further study. In a zymographic analysis, gelatinolytic activity for cationic trypsinogen was detectable in serum-free conditioned media obtained from all 4 transfectants but not in media from mock-transfected or parental Panc-1 cells. A Matrigel invasion assay revealed that all trypsinogen-expressing transfectants acquired significantly greater invasive ability than that shown by mock-transfected and parental Panc-1 cells. In addition, enhanced invasiveness of the transfectants was suppressed by FUT-175, a serine protease inhibitor, to the level seen in parental cells. These results provide direct evidence that cationic trypsinogen can increase the invasive ability of carcinoma cells.

Liver abscesses associated with stromal tumour of the stomach in a young woman

A 23-year-old Japanese woman was admitted to hospital because of pyrexia and anaemia. She was found to have liver abscesses and a gastric submucosal mass by computed tomography and ultrasonography. Gastroscopy and a barium swallow revealed a round submucosal mass with a giant ulceration in the body of the stomach. The liver abscesses were successfully treated by percutaneous transhepatic drainage and intravenous administration of antibiotics. Cultures of the fluid from a liver abscess and gastric juice yielded alpha-haemolytic streptococci. Three weeks after the drainage, partial gastrectomy was performed. The tumour was diagnosed as a stromal tumour of the stomach (leiomyosarcoma) in the final histological report. The patient was discharged on postoperative day 17 without receiving adjuvant radio-chemotherapy. There have been no signs of recurrence two years after surgery. This is a rare case of a liver abscess associated with a stromal tumour of the stomach in a young patient. The bacteriological examinations suggested a possible association between these diseases.

Crystallization and preliminary X-ray analysis of a DNA primase from hyperthermophilic archaeon Pyrococcus horikoshii

At the initiation of chromosomal DNA replication, DNA primases synthesize short RNA primers, which are subsequently elongated by DNA polymerases. To understand the structural basis for the primer synthesis by archaeal/eukaryotic-type primases, the gene of the DNA primase from hyperthermophilic archaeon Pyrococcus horikoshii was cloned and overexpressed in Escherichia coli as a fusion protein with a hexa-histidine tag at its amino terminus. The recombinant DNA primase was purified and crystallized by the hanging-drop vapor diffusion method at 293 K, with polyethylene glycol 8000 as the precipitant. The crystals belong to the P3(2)21 space group with unit-cell parameters a = b = 77.8, c = 129.6 A, and alpha = beta = 90 degrees, gamma = 120 degrees. Crystals of the selenomethionine derivative were obtained by means of a cross-seeding method using native crystals. The data for the native and selenomethionine-substituted crystals were collected to 1.8 and 2.2 A resolution, respectively, with synchrotron radiation at SPring-8 under flash-frozen conditions at 100 K. The four wavelength MAD data provided a phase to determine the structure of the primase at 2.2 A resolution.

Crystal structure of human AUH protein, a single-stranded RNA binding homolog of enoyl-CoA hydratase

BACKGROUND

The AU binding homolog of enoyl-CoA hydratase (AUH) is a bifunctional protein that has two distinct activities: AUH binds to RNA and weakly catalyzes the hydration of 2-trans-enoyl-coenzyme A (enoyl-CoA). AUH has no sequence similarity with other known RNA binding proteins, but it has considerable sequence similarity with enoyl-CoA hydratase. A segment of AUH, named the R peptide, binds to RNA. However, the mechanism of the RNA binding activity of AUH remains to be elucidated.

RESULTS

We determined the crystal structure of human AUH at 2.2 A resolution. AUH adopts the typical fold of the enoyl-CoA hydratase/isomerase superfamily and forms a hexamer as a dimer of trimers. Interestingly, the surface of the AUH hexamer is positively charged, in striking contrast to the negatively charged surfaces of the other members of the superfamily. Furthermore, wide clefts are uniquely formed between the two trimers of AUH and are highly positively charged with the Lys residues in alpha helix H1, which is located on the edge of the cleft and contains the majority of the R peptide. A mutational analysis showed that the lysine residues in alpha helix H1 are essential to the RNA binding activity of AUH.

CONCLUSIONS

Alpha helix H1 exposes a row of Lys residues on the solvent-accessible surface. These characteristic Lys residues are named the "lysine comb." The distances between these Lys residues are similar to those between the RNA phosphate groups, suggesting that the lysine comb may continuously bind to a single-stranded RNA. The clefts between the trimers may provide spaces sufficient to accommodate the RNA bases.

A case of non-functioning pituitary adenoma with Cushing's syndrome upon recurrence

A 49-year-old woman presented with left visual disturbance. No signs of Cushing's disease were evident. Basal levels of serum cortisol and plasma adrenocorticotropic hormone (ACTH) were 16.8 microg/dL and 66.0 pg/mL, respectively. MRI demonstrated an irregularly shaped large pituitary tumor, and the patient then underwent transsphenoidal surgery. By light microscopy the tumor represented a chromophobic adenoma with a few of the adenoma cells showing immunoreactivity for ACTH. On the basis of clinical and light microscopic examinations, the diagnosis of silent corticotroph adenoma was made. Electron microscopy, however, demonstrated the honeycomb Golgi complex that has been reported as a typical finding of gonadotroph adenomas. MRI taken 7 months after the first operation revealed adenoma regrowth. Transcranial surgery was performed, and histology demonstrated a chromophobic pituitary adenoma with most cells immunopositive for ACTH. She was treated with gamma knife postoperatively. Three months later, MRI revealed remarkable shrinkage of the adenoma, but she developed typical signs and symptoms of Cushing's disease. Thus, the hormone immunostaining and biological activity of pituitary adenomas may change with time.

Shifted positioning of the anticodon nucleotide residues of amber suppressor tRNA species by Escherichia coli arginyl-tRNA synthetase

Cytidine in the anticodon second position (position 35) and G or U in position 36 of tRNAArg are required for aminoacylation by arginyl-tRNA synthetase (ArgRS) from Escherichia coli. Nevertheless, an arginine-accepting amber suppressor tRNA with a CUA anticodon (FTOR1Delta26) exhibits suppression activity in vivo [McClain, W.H. & Foss, K. (1988) Science, 241, 1804-1807]. By an in vitro kinetic study with mutagenized tRNAs, we showed that the arginylation of FTOR1Delta26 involves C34 and U35, and that U35 can be replaced by G without affecting the activity. Thus, the positioning of the essential nucleotides for the arginylation is shifted to the 5' side, by one residue, in the suppressor tRNAArg. We found that the shifted positioning does not depend on the tRNA sequence outside the anticodon. Furthermore, by a genetic method, we isolated a mutant ArgRS that aminoacylates FTOR1Delta26 more efficiently than the wild-type ArgRS. The isolated mutant has mutations at two nonsurface amino-acid residues that interact with each other near the anticodon-binding site.

Crystal structure of thermostable DNA photolyase: pyrimidine-dimer recognition mechanism

DNA photolyase is a pyrimidine-dimer repair enzyme that uses visible light. Photolyase generally contains two chromophore cofactors. One is a catalytic cofactor directly contributing to the repair of a pyrimidine-dimer. The other is a light-harvesting cofactor, which absorbs visible light and transfers energy to the catalytic cofactor. Photolyases are classified according to their second cofactor into either a folate- or deazaflavin-type. The native structures of both types of photolyases have already been determined, but the mechanism of substrate recognition remains largely unclear because of the lack of structural information regarding the photolyase-substrate complex. Photolyase from Thermus thermophilus, the first thermostable class I photolyase found, is favorable for function analysis, but even the type of the second cofactor has not been identified. Here, we report the crystal structures of T. thermophilus photolyase in both forms of the native enzyme and the complex along with a part of its substrate, thymine. A structural comparison with other photolyases suggests that T. thermophilus photolyase has structural features allowing for thermostability and that its light-harvesting cofactor binding site bears a close resemblance to a deazaflavin-type photolyase. One thymine base is found at the hole, a putative substrate-binding site near the catalytic cofactor in the complex form. This structural data for the photolyase-thymine complex allow us to propose a detailed model for the pyrimidine-dimer recognition mechanism.