[A case of recurrent gastric cancer during adjuvant chemotherapy with S-1, treated by S-1 combination chemotherapy].

A 59-year-old man was admitted to our hospital for the treatment of gastric cancer with synchronous and multiple metastatic liver tumors. After total gastrectomy in February 2005, partial resection of the posterior segment of the liver was carried out in the next month. Pathological study of both the resected specimens showed moderately differentiated adenocarcinoma.

Phosphorothioate hammerhead ribozymes targeting a conserved sequence in the V3 loop region inhibit HIV-1 entry.

Seven different phosphorothioate DNA-RNA chimeric hammerhead ribozymes (RzV3-nT, n = 1-7) targeted against the V3 loop region of HIV-1 were synthesized. Two of these, RzV3-1T and RzV3-3T, efficiently cleaved transcribed envelope RNA of HXB2 in vitro. The target sequence of RzV3-1T belongs to a conserved region and is completely identical in the HIV-1 HXB2, NL432, and ADA strains.

Phosphorothiolate ribozyme against the conserved sequence in V3 loop of HIV-1.

Fluorescent-labeled phosphorothiolate DNA-RNA chimeric hammerhead ribozyme (thio-Rz) was synthesized. The ribozyme recognizes relatively conserved sequences in the functionally important region (V3 loop) of envelope protein of HIV-1. The thio-Rz as well as wild-type ribozyme cleaved RNA transcripts (414 base) of V3 region in a dose-dependent manner.

Enhanced E-cadherin expression and increased calcium-dependent cell-cell adhesion in human T-cell leukemia virus type I Tax-expressing PC12 cells.

Human T-cell leukemia virus type I (HTLV-I) Tax protein induces the expression of host cellular genes, some of which are crucial in cell proliferation and differentiation. We examined the mechanisms by which HTLV-I Tax protein induces phenotypic changes in PC12 cells. We demonstrated that the HTLV-I Tax gene induces epithelioid changes and increases cell-cell contact in PC12 cells.

Extraordinary enhancement of the cleavage activity of a DNA-armed hammerhead ribozyme at elevated concentrations of Mg2+ ions.

As part of an ongoing effort to characterize structure-function relationships, activities of all-RNA and DNA-armed hammerhead ribozymes were examined. An analysis of the dependence on the concentration of Mg2+ ions of cleavage rates revealed that, whereas the kcat of the reaction catalyzed by the all-RNA ribozyme reached a maximum value of about 18 min-1 at a concentration of about 200 mM Mg2+ ions, that of the DNA-armed ribozyme increased linearly as the concentration of Mg2+ ions was increased above 300 mM, finally reaching a value of more than 100 min-1 at 700 mM Mg2+ ions. These results suggest that the potential activity of a hammerhead ribozyme might be greater than is usually recognized.

Generality of the NUX rule: kinetic analysis of the results of systematic mutations in the trinucleotide at the cleavage site of hammerhead ribozymes.

In order to study in detail the generality of the NUX (N = A, U, G, or C; X = A, U, or C) rule for the GUC triplet adjacent to the cleavage site in hammerhead ribozymes, two kinetic parameters, namely, kcat and Km, were determined for substrates with mutations in this triplet, which included double mutants with mutations of both N and X. All substrates with mutated cleavage sites were cleaved with reduced efficiency compared to the wild type. However, some mutations mainly affected kcat and others mainly affected Km, a phenomenon that could not have been predicted from previous results.

Effects of deoxyribonucleotide substitutions in the substrate strand on hammerhead ribozyme-catalyzed reactions.

In order to examine the effects of deoxyribonucleotide substitutions in the substrate strand, several chimeric DNA/RNA substrates for a hammerhead ribozyme were chemically synthesized. Measurements of kinetic parameters revealed that a chimeric DNA/RNA substrate, that contained GUC at the cleavage site as ribonucleotides, was cleaved by an all-RNA ribozyme with a threefold higher kcat than that of the wild-type (wt) reaction. Moreover, this chimeric substrate was also cleaved by a DNA-armed ribozyme that has a higher kcat than the all-RNA ribozyme [Shimayama et al.

High-resolution NMR study of a synthetic oligoribonucleotide with a tetranucleotide GAGA loop that is a substrate for the cytotoxic protein, ricin.

Ricin is a cytotoxic protein that inactivates ribosomes by hydrolyzing the N-glycosidic bond at position A4324 in eukaryotic 28S rRNA. Its substrate domain forms a double helical stem and a 17-base loop that includes the sequence GAGA, the second adenosine of which corresponds to A4324. Recently, studies of mutant RNAs have shown that the four-nucleotide loop, GAGA, can function as a substrate for ricin.

Enhancement of the cleavage rates of DNA-armed hammerhead ribozymes by various divalent metal ions.

In order to characterize structure-function relationships, the kinetic behavior of chimeric RNA/DNA ribozyme was compared with that of all RNA ribozyme. Determined kcat values were proven to represent the chemical-cleavage step and not the product-dissociation step. In agreement with the finding by Dahm and Uhlenbeck [Biochemistry 30, 9464-9469 (1991)], various metal ions, including Co2+ and Ca2+ with the ionic radius of 0.

Nuclease-resistant chimeric ribozymes containing deoxyribonucleotides and phosphorothioate linkages.

Hammerhead ribozymes are considered to be potential therapeutic agents for HIV virus because of their site-specific RNA cleavage activities. In order to elucidate structure--function relationship and also to hopefully endow ribozymes with resistance to ribonucleases, we firstly synthesized chimeric DNA/RNA ribozymes in which deoxyribonucleotides were substituted for ribonucleotides at noncatalytic residues (stems I, II, and III). Kinetic analysis revealed that (i) DNA in the hybridizing arms (stems I and III) enhanced the chemical cleavage step.

Right common iliac arterio-intestinal fistula caused by tubercular peritonitis: report of a case.

A 59-year-old female was admitted with massive hematemesis and melena. A hematological examination revealed that the red blood cell count was 1.31 x 10(6)/mm3, Hb 3.

Theoretical analyses on the role of metal cations in RNA cleavage processes.

Previously, we found that locations of metal cations in biomolecules, such as proteins and nucleotides, were in accord with predictions based on electrostatic-potential calculations of the nearest polar functional groups. Electrostatic potential of a cyclic oxyphosphorane dianion 2, which is a model compound for an intermediate or a transition state for the hammerhead ribozyme reaction, indicates that Mg2+ coordinations at the regions between axial (bridging) and equatorial (phosphoryl) oxygens are most favorable. If we consider the fact that negative charge is concentrated on two of the equatorial phosphoryl oxygens in the transition state 2, the axial-equatorial coordination is an unexpected result.

Cleavage of the highly conserved hairpin-loop region of HIV-1 by synthetic ribozymes.

Hammerhead ribozymes can be considered as molecular scissors for suppressing AIDS virus. It is attractive to target single-stranded region of HIV-1 RNA because single-stranded RNA interactions or "kissing" induce hybridization. We, therefore, chose a highly conserved hairpin-loop structure, that is located in the 5' long terminal repeat region and just downstream of the TAR regulatory sequence.

Substitution of non-catalytic stem and loop regions of hammerhead ribozyme with DNA counterparts only increases KM without sacrificing the catalytic step (kcat): a way to improve substrate-specificity.

In elucidating structure-function relationships and stabilizing ribozymes in vivo, several chimeric RNA/DNA ribozymes and substrates were chemically synthesized. Measurements of kinetic parameters revealed that the maximally deoxyribonucleotide-substituted ribozyme (DRDRD32) gained the highest catalytic activity reaching the kcat value of > 10 min-1, the highest value ever reported for hammerhead-type ribozymes. Since these chimeric ribozymes are more stable than the wild-type all-RNA ribozymes in vivo and they also possess higher substrate-specificity, they are considered to be better candidates for antiviral therapeutic agents.

The genetic code of a squid mitochondrial gene.

Cytochrome oxidase subunit I gene of a squid (Mollusca), Doryteuthis mitochondrial genome was sequenced. Comparison with the nucleotide sequence and the deduced amino acid sequence of other animal mitochondria suggests that the squid mitochondria has a variation in the genetic code; UGA codes for tryptophan, AUA for methionine and AGA/G for serine. This situation is similar to the case of Drosophila or Ascaris mitochondria.

[A case of Morgagni's hernia complicated with esophageal hiatus hernia].

A rare case of Morgagni's hernia complicated with esophageal hiatus hernia is reported. A 85-year-old female suffered from swallowing disturbance admitted for evaluation of abnormal finding on chest X-ray film. The diagnosis was confirmed by chest roentgenogram, gastro-intestinal series and CT scan.

Iron deficiency anemia caused by a giant jejunal diverticulum.

We treated a patient with a jejunal diverticulum with a rare complication of iron deficiency anemia. The anemia was improved following resection of the diverticulum. It was revealed that the iron deficiency anemia was due to the malabsorption caused by the jejunal diverticulum.

Strongyloides stercoralis hyperinfection: sequential changes of gastrointestinal radiology after treatment with thiabendazole.

Sequential changes of gastrointestinal radiology are described in a case of Strongyloides stercoralis hyperinfection. Duodenal dilatation, reflux of barium into the biliary and pancreatic duct, and mucosal thickening of the small intestine were the striking features before treatment. Although treatment with thiabendazole led to rapid and complete clearance of rhabditiform larvae, some abnormal radiologic changes in the small intestine persisted for approximately 4 months before the mucosal pattern reverted to normal.