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Biomedical subjects

Y Nagamachi

Publications and source records attributed to Y Nagamachi.

At least 37 records · Page 2Linked to original sources
PubMed1998

Cloning, differential regulation and tissue distribution of alternatively spliced isoforms of ADP-ribosylation-factor-dependent phospholipase D from rat liver.

An alternatively spliced isoform of ADP-ribosylation-factor-dependent phospholipase D (PLD1) was previously shown to occur in rat C6 cells [Yoshimura, Nakashima, Ohguchi, Sakai, Shinoda, Sakai and Nozawa (1996) Biochem. Biophys. Res. Commun. 225, 494-499] and human HeLa cells [Hammond, Jenco, Nakashima, Cadwallader, Gu, Cook, Nozawa, Prestwich, Frohman and Morris (1997) J. Biol. Chem. 272, 3860-3868]. However, its complete sequence and the enzymological difference between the two PLD1 isoforms were unclear. Here we report the cloning, complete sequence, enzymological properties and tissue distribution of each of the two alternatively spliced PLD1 isoforms, a and b, from rat liver. The major difference between the two isoforms was the deletion of 38 amino acids in the b isoform, but otherwise the two cDNA sequences were 99.9% identical. The a-isoform sequence was 91% identical with the a form of human PLD1, and the 38-amino-acid deletion in the b form occurred at the same site as in the b form of human PLD1. Both of the rat PLD1 isoforms expressed in the fission yeast Schizosaccharomyces pombe were dependent on ADP-ribosylation factor 1 and phosphatidylinositol 4,5-bisphosphate. The a isoform was activated by RhoA in a synergistic manner with ADP-ribosylation factor 1, whereas the b isoform was less responsive to RhoA. Reverse transcription PCR showed that the b form was the predominant PLD1 isoform expressed in rat tissues. The b-form transcript occurred in various rat tissues, including lung, brain, liver, kidney, small intestine and colon, whereas the a-form transcript was only detectable in lung, heart and spleen. Both transcripts were hardly detectable in thymus, stomach, testis and muscle. Thus the two PLD1 isoforms were differently regulated and expressed in rat tissues.

ADP-Ribosylation Factors↗
PubMed1998

An evaluation of motor function in transverse colon transplants after total gastrectomy.

The motor activity of the isolated colon is understood less than that of any other part of the gastrointestinal viscus. Thus, the aim of the present study was to evaluate the motor activity of the interposed transverse colon following total gastrectomy through a study of 21 patients. Manometric studies were carried out with a 5-lumen, open-tipped catheter in the resting state, in response to dry swallows, and swallowing distilled water and a liquid meal. Contractile waves in the interposed colon grafts were divided into three types, namely, high-amplitude propagated contractions (HAPCs), low-amplitude propagated contractions (LAPCs), and low-amplitude nonpropagated contractions (LANPCs). No retrograde contractions were observed during the entire recording. Motor activity in the interposed colon increased to a greater extent after swallowing distilled water or liquid meals than during the resting period or after dry swallows; however, there was no significant difference between the effect of distilled water and liquid meals. The motor activity of the interposed colon was lower in patients with symptoms than in asymptomatic patients. These results suggest that the volume, rather than the composition, of the lumen contents is an important factor for inducing interposed colon graft contractions, and that contractions of the interposed colon can help to propel the contents of the colon into the duodenum and clear any duodenal juice if reflux should occur.

Anastomosis, Surgical↗
PubMed1998

Genomic structure and chromosomal localization of the mouse Ogg1 gene that is involved in the repair of 8-hydroxyguanine in DNA damage.

8-Hydroxyguanine (7,8-dihydro-8-oxoguanine: oh8Gua) is a damaged form of guanine induced by oxygen-free radicals and causes GC to TA transversions. Previously we isolated the hOGG1 gene, a human homolog of the yeast OGG1 gene, which encodes a DNA glycosylase and lyase to excise oh8Gua in DNA. In this study, we isolated a mouse homolog (Ogg1) of the OGG1 gene, characterized oh8Gua-specific DNA glycosylase/AP lyase activities of its product, and determined chromosomal localization and exon-intron organization of this gene. A predicted protein possessed five domains homologous to human and yeast OGG1 proteins. Helix-hairpin-helix and C2H2 zinc finger-like DNA-binding motifs found in human and yeast OGG1 proteins were also retained in mouse Ogg1 protein. The properties of a GST fusion protein were identical to human and yeast OGG1 proteins in glycosylase/lyase activities, their substrate specificities, and suppressive activities against the spontaneous mutagenesis of an Escherichia coli mutM mutY double mutant. The mouse Ogg1 gene was mapped to Chromosome (Chr) 6, and consisted of 7 exons approximately 6 kb long. Two DNA-binding motifs were encoded in exons 4 through 5. These data will facilitate the investigation of the OGG1 gene to elucidate the relationship between oxidative DNA damage and carcinogenesis.

Amino Acid Sequence↗
PubMed1998

Mechanism of inhibitory effect of glucagon on gastrointestinal motility and cause of side effects of glucagon.

Glucagon is commonly used during gastrointestinal examinations for the temporary inhibition of gastroduodenal movements. Three preparations of glucagon are now clinically available: those prepared by extraction from the pancreas (GL-P), by chemical synthesis (GL-S), and by genetic recombination (GL-G). The aim of this study was examine the mechanism of the inhibitory effect of glucagon on gastrointestinal motility and the cause of its side effects by comparing three glucagon preparations. In four conscious dogs, gastrointestinal contractions were monitored by means of chronically implanted force transducers. Each glucagon preparation (GL-P [15 microg/kg], GL-S [5, 15, 45 microg/kg], GL-G [15 microg/kg]), scopolamine butylbromide (0.4 mg/ kg), or saline was administered intravenously 20 min after the termination of spontaneous phase III contractions, and blood samples were taken at 5- to 10-min intervals. Barium was administered into the stomach 10 min after the infusion of each drug. The arrival of a barium meal in the stomach immediately stimulated gastrointestinal contractions, and the barium meal was expelled into the duodenum and jejunum from the stomach. Intravenous injection of 15 microg GL-S first stimulated duodenal contractions that propagated to the jejunum, followed by strong inhibition of the barium-induced gastrointestinal contractions. This inhibitory effect of glucagon and the activity of the glucagon-induced duodenal contractions were dose-related. The inhibitory effects of GL-G and GL-S were stronger than that of GL-P. Blood glucose and plasma insulin concentrations were raised after intravenous injection of each glucagon preparation, but there was no difference among the three preparations and no dose relationship. The inhibitory effects of glucagon depend on the material purity and dose, and the inhibitory mechanism was independent of any effect on carbohydrate metabolism. Glucagon administration caused phase III-like contractions in the duodenum and jejunum, which may be responsible for the side effects of glucagon.

Analysis of Variance↗
PubMed1998

Mutation analysis of the Smad2 gene in human colon cancers using genomic DNA and intron primers.

In mammals, one of the Mad homologues, Smad2, was reported to be a mediator of TGF-beta signaling, and was found mutated in some cases of colon and lung cancers. To extend the analysis of this gene, we previously investigated the genomic organization of the human Smad2 gene and defined the structure of 12 exons and flanking introns. In this study, we designed 11 sets of intron-based primers to examine the entire coding region of the Smad2 gene. By the PCR-SSCP method using these primers, we screened genomic DNA sequences of colorectal cancers for mutations of the Smad2 gene. Though there was no mutation within all exons of the Smad2 gene, two of 60 sporadic colorectal cancers displayed deletions in the polypyrimidine tract preceding exon 4. Deletions of this region were also detected in colon cancer cell lines, and were clustered within cells exhibiting microsatellite instability. Deletions in the polypyrimidine tract had various effects on pre-mRNA splicing, but had no effect on the splicing of the Smad2 gene in these cases. However, our data support the idea that the polypyrimidine tract in the splicing acceptor site is a target of mutations in mismatch repair-deficient tumors.

Base Sequence↗
PubMed1998

Acute in vivo effect of octreotide acetate, a somatostatin analogue on the cellular function of gastric mucosa in the rat.

Somatostatin is known to suppress various cellular functions of the gastrointestinal tract. In the present study, octreotide acetate, a synthetic long-acting somatostatin analogue was tested for its effects on some cellular functions of gastric mucosa. Octreotide raised the gastric mucosal pH within 1 h after a single subcutaneous injection to rats at doses of 1-100 microg/kg bodyweight. Serum gastrin levels increased transiently at a dose of 10 microg/kg bodyweight but not at 100 microg/kg. Basal levels of serum gastrin were not affected, while famotidine-induced gastrin secretion was suppressed by octreotide at a single dose of 100 microg/kg. The increase in the intragastric acidity and histidine decarboxylase activity following pentagastrin treatment was significantly reduced by octreotide. These results suggested that this somatostatin analogue inhibits the function of not only the parietal cell and G cell but also the enterochromaffin-like (ECL) cell, resulting in intraluminal hypoacidity.

Animals↗
PubMed1998

Mutation of the transforming growth factor-beta type II receptor gene is a rare event in human sporadic gastric carcinomas.

Mutations of the transforming growth factor-beta type II receptor (TGF-beta RII) gene have been detected in several human cancers. However, mutation analysis of coding sequences of TGF-beta RII in gastric carcinomas has not yet been fully elucidated. We performed PCR-SSCP analysis and direct DNA sequencing of the entire coding region of TGF- RII in 38 human sporadic gastric cancers and 8 gastric cancer cell lines. Mutations of the TGF-beta RII were detected in two tumors and three cell lines. Two tumors had one base deletion in the polyadenine tract in exon 3, the cystein-rich extracellular domain. Three cell lines had a silent mutation in the kinase domain located in exon 4. Polymorphisms were detected in introns 2 and 3. An a/g polymorphism was observed at the seventh base in intron 2 and an a/t polymorphism was observed at the fourth to last base in intron 3. There were no mutations in exons 1, 2, 5, 6 and 7. These results indicate that the polyadenine tract in the TGF-beta RII is a mutational hot spot in human gastric cancer. However, these results also suggest that mutations of the gene are rare events in human sporadic gastric cancer.

DNA Primers↗
PubMed1997

Presence of human cellular protein(s) that specifically binds and cleaves 8-hydroxyguanine containing DNA.

8-hydroxyguanine (oh8Gua) is a major form of oxygen free radical-induced DNA damage. The oh8Gua nucleotide can pair with cytosine (C) and adenine (A) nucleotides which can cause G:C to T:A transversions. It is known that multiple repair systems for the correction of the oh8Gua exist in both mammalian and bacterial cells. Using the technique of gel mobility shift assay, protein(s) bound to the oh8Gua:C base pair in short fragments of DNA was detected in cell-free extracts of a human small-cell lung cancer cell line. This DNA binding activity was specific, since it was poorly detected with an unmodified G:C base pair containing oligonucleotide duplex and was affected by neither the unmodified G:C base pair nor an oh8Gua:A base pair containing oligonucleotide duplex. The partially purified protein which selectively binds to the oh8Gua:C base pair was shown by gel filtration column chromatography to have an apparent molecular mass of 52 kDa. The column fraction which showed the highest binding activity to the oh8Gua:C base pair was found to possess an enzymatic activity that specifically cleaves the oh8Gua containing oligonucleotide strand at both the 5' and 3' sides of the oh8Gua residue. These results indicate the presence of a protein(s) that is involved in a DNA repair pathway for the correction of the oh8Gua residue in human cells.

DNA Repair↗
PubMed1997

Isolation of a novel Sry-related gene that is expressed in high-metastatic K-1735 murine melanoma cells.

To identify genes differentially expressed in association with metastatic potential of K-1735 mouse melanoma cells, the mRNA differential display method was applied to compare mRNAs from high- and low-metastatic K-1735 cells. A novel gene was identified as being expressed in high-metastatic cells but not in low-metastatic cells. Sequence analysis revealed that this gene had an open reading frame of 538 amino acid residues containing a Sry high-mobility group (HMG) box domain, known as a DNA binding motif, particularly in the Sox family genes. This gene showed the highest homology to the human SOX9 gene, which is the responsible gene for an inherited disease, campomelic dysplasia. Thus, this gene was designated the Sox21 gene (the 21st Sox family gene). The Sox21 gene was mapped to mouse Chromosome 15, to which neither genes containing the HMG box region nor the loci of hereditary diseases similar to campomelic dysplasia have been previously mapped. This gene was highly conserved and specifically expressed in the brain. These results suggest that expression of the Sox21 gene is involved in the development of nerve systems and may function to enhance the metastatic potential of K-1735 mouse melanoma cells of nerve cell origin.

Amino Acid Sequence↗
PubMed1997

Intra-mesenteric artery steroid administration relieved severe refractory gastro-intestinal graft-vs.-host disease in an allogeneic bone marrow transplantation patient.

We report a case of severe gastro-intestinal (G-I) graft-vs.-host disease (GVHD) successfully treated with intra-mesenteric artery steroid administration. A 29-year-old man with severe aplastic anemia (SAA) was submitted to HLA-identical unrelated allogeneic bone marrow transplantation (BMT) and was found to be suffering from grade IV G-I GVHD. Although cyclosporine, steroid pulse therapy, and FK506 proved ineffective, 30 mg of water-soluble prednisolone as administered into each the superior and inferior mesenteric artery with remarkable effects. This treatment was repeated two times, and the symptoms of G-I GVHD disappeared completely.

Adult↗
PubMed1997

Increased phospholipase D activity in human breast cancer.

Phospholipase D is believed to play an important role in cell proliferation and tumorigenesis. One of its major functions is to cause a sustained activation of protein kinase C through the primary production of phosphatidic acid from phosphatidylcholine by the enzyme, followed by dephosphorylation forming diacylglycerol. Protein kinase C is known to be activated or translocated in some tumors including breast tumors. In order to examine phospholipase D activity in breast tumors, surgical specimens of human breast tumors were obtained by mastectomy or wide excision, and their phospholipase D activities were assayed by determining the formation of phosphatidylethanol from phosphatidylcholine and ethanol. Phospholipase D activity was predominantly localized in the microsomal fraction of the tumor tissue and markedly stimulated by oleic acid. We observed a significant increase in phospholipase D activity in 17 out of 19 spontaneous human breast tumors as compared to adjacent histologically normal breast tissue. The mean specific activity in the tumors was 52.9 +/- 41.8 (SD) pmol min-1 mg protein-1 whereas the value for the normal breast tissue was 34.0 +/- 36.2 (SD) pmol min-1 mg protein-1 (P < 0.01; paired Wilcoxon's rank-sum test). The mean tumor/normal activity ratio was 2.37. Among prognostic factors, the nuclear grade, evaluated according to Schnitt et al., was found to be correlated with the activity ratio. Our results suggest a role for phospholipase D in human breast tumors. An elevation in phospholipase D activity is useful as a potential marker for malignant disease in the breast.

Adult↗
PubMed1997

Effectiveness of Tc-99m MIBI scintigraphy in diagnosing lung cancer.

The use of Tc-99m hexakis 2-methoxy isobutyl isonitrile (MIBI) scintigraphy for qualitative diagnosis was examined. A total of 37 lesions from 31 patients with respiratory disease (19 lesions from 19 primary lung cancer patients, 8 lesions from 3 metastatic lung cancer patients and 10 lesions from benign lung disease patients) were examined. Positive results were seen in 89.4% of the primary lung cancer lesions, 50.0% of the metastatic lung cancer lesions, and 20.0% of the benign lung disease lesions. The positive rate of 77.7% for malignant lung cancer was significantly higher (P < 0.01) than that for benign lung cancer. In particular, for lesions with a tumor diameter of 1.0 cm or more, the positive rate for malignant lung cancer lesions (95.2%) was significantly higher (P < 0.001) than that for benign lung disease lesions (25.0%). These results thus indicate Tc-99m MIBI scintigraphy to be useful for qualitative diagnosis of lung peripheral coin lesions with a diameter of 1.0 cm or more.

Adenocarcinoma↗
PubMed1997

A new fine probe for electric cautery during endoscopic surgery.

The present paper introduces a new fine probe for electric cautery (1.65 mm in diameter, 22 cm long) that can be connected to a conventional cylindrical hand-controlled cautery holder, which is monopolar and widely used in general surgery. When cautery was required, a 14-gauge intravenous catheter was inserted at an appropriate site under the guidance of a videoscope. After removing the steel inner needle, the extra tube was used as the fine surgical port for the cautery probe. The position of insertion could be altered according to the operating field. Cautery was performed by conventional methods. There was no bleeding or air leakage at the site of puncture during or after surgery. The puncture wound was closed without any sutures. Based on these results, the new fine probe for cautery can reduce the number of surgical ports required for instruments during video-assisted surgery, thus improving the ease and safety of endoscopic surgery.

Electrocoagulation↗
PubMed1997

Suppression of histidine decarboxylase activity in rat oxyntic mucosa by beraprost sodium, a prostacyclin analogue.

Prostaglandins (PGs) affect various aspects of gastric functions. In the present study the orally administered PGI2 derivative beraprost sodium (TRK-100.1 micrograms per kg body weight) decreased oxyntic histidine decarboxylase activity without changing serum gastrin levels. Antral pH increased 4 hr after treatment. Beraprost also decreased the pentagastrin-induced histidine decarboxylase activity at the same dose. Serum levels of secretin, somatostatin and glucose, and oxyntic mucosal levels of histamine and somatostatin, showed no significant change after treatment with beraprost. These results suggest that the response of oxyntic histidine decarboxylase to gastrin is modified by one or more prostanoids including PGI2. This mechanism might play a role in gastric mucosal protection.

Animals↗
PubMed1997

The usefulness of anti-fucosylated antigen antibody YB-2 for diagnosis of hepatocellular carcinoma.

Levels of fucosylated antigens in sera from patients with liver diseases were examined by a newly developed sandwich-type enzyme immuno assay with the aid of anti-fucosylated antigen antibody, YB-2 which reacts simultaneously with Y, Leb and H type 2 antigens. When the cut-off value was set arbitrarily at mean +3 SD values of normal, 30 (69.8%) of the 43 patients with HCC, 14 (53.8%) of the 26 patients with liver cirrhosis (LC) and 24 (45.3%) of the 53 patients with chronic hepatitis (CH) were found to be positive, whereas all of the 30 samples from healthy controls were negative. The levels of alpha-fetoprotein (AFP) and protein induced by vitamin K absence or antagonist-II (PIVKA-II) in HCC were not correlated with those of YB-2 antigens. The positive rates of the combination YB-2 and AFP assay and YB-2 and PIVKA-II assay in HCC were significantly higher (83.7 and 86.0%, respectively) than that of the AFP and PIVKA-II combination (65.1%) which had been reported to be the best combination up to this time.

Adult↗
PubMed1997

Lung carcinogenesis and formation of 8-hydroxy-deoxyguanosine in mice by diesel exhaust particles.

In order to clarify the involvement of oxygen radicals in lung carcinogenesis induced by diesel exhaust particles (DEP), the relationship between lung tumour response and formation of 8-hydroxydeoxyguanosine (8-OHdG) in lung DNA was examined. The role of high dietary fat and beta-carotene on these responses was also studied. Mice were intratracheally injected with 0.05, 0.1 and 0.2 mg of DEP per animal once weekly for 10 weeks. After 12 months, the lung tumour incidence in mice treated with 0.05 mg and 0.1 mg showed similar increases (30% and 31%), but was decreased to 24% at 0.2 mg. High dietary fat enhanced the incidence of both benign and malignant tumours. beta-carotene partially prevented the tumour development. After the 10 weekly treatments of DEP, inflammatory reaction was observed in the respiratory tract and alveoli. The formation of 8-OHdG in lung DNA from mice treated with DEP showed a dose dependent increase. 8-OHdG formation was enhanced by high dietary fat and partially reduced by beta-carotene. Formation of 8-OHdG was significantly correlated with the lung tumour incidence except at 0.2 mg. These results suggest that the induction of oxidative DNA damage may be an important factor in the initiation of DEP-induced lung carcinogenesis, and that beta-carotene and high dietary fat may play a role in the regulation of tumour development via modulation of the formation of 8-OHdG.

8-Hydroxy-2'-Deoxyguanosine↗