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Biomedical subjects

A Iwamoto

Publications and source records attributed to A Iwamoto.

At least 145 records · Page 8Linked to original sources
PubMed1992

Short sequence in L1 region of human papillomaviruses correlates with clinical pictures and grouping by cross-hybridization.

A consensus primer-mediated polymerase chain reaction devised to amplify a short sequence in L1 region (L1-PCR) efficiently detected genital human papillomaviruses (HPVs) in clinical materials. Nucleotide sequencing of the amplified fragment showed that L1-PCR is also applicable to hitherto unsequenced HPVs. By comparing the amplified 210 nucleotides HPVs were classified into six groups, which are consistent with clinical pictures and a grouping based on cross-hybridization under the stringent condition.

Base Sequence↗
PubMed1992

Escherichia coli ATP synthase (F-ATPase): catalytic site and regulation of H+ translocation.

We discuss our recent results on the Escherichia coli F-ATPase, in particular its catalytic site in the beta subunit and regulation of H+ transport by the gamma subunit. Affinity labelling experiments suggest that beta Lys-155 in the glycine-rich sequence is near the gamma-phosphate moiety of ATP bound at the catalytic site. The enzyme loses activity upon introduction of missense mutations in beta Lys-155 or beta Thr-156 and changes catalytic properties upon introduction of other mutations. By analysis of mutations and their pseudo revertants, residues beta Ser-174, beta Glu-192 and beta Val-198 were found to be located near the glycine-rich sequence. The combined approaches of chemical labelling and genetics have been fruitful in visualizing the structure of the catalytic site. Analysis of mutations in the gamma subunit suggests that this subunit has an essential role in coupling catalysis with proton translocation.

Amino Acid Sequence↗
PubMed1992

Lymph nodal vital staining with newer carbon particle suspensions compared with India ink: experimental and clinical observations.

CH40 and CH1500AA are newly prepared carbon suspensions which were examined as vital staining dyes for their usefulness in visualizing lymphatics at operation and to blacken lymph nodes. In mice, these carbon suspensions at 0.001 ml/g of body weight and India ink were injected subcutaneously into the footpad of the right hindpaw. Regional lymph nodes were visualized and were examined stereomicroscopically to determine how intensely these nodes blackened with carbon suspensions. Compared with India ink, CH40 and CH1500AA blackened the regional lymph nodes much faster and more vividly (1-8 min. after subcutaneous injection). As analyzed by centrifugal particle size distribution, CH40 and CH1500AA are narrowly distributed with a small particle size (150 and 167 nm, respectively, in mean diameter). By contrast, India ink is comprised of widely distributed and relatively large particles in suspension (mean diameter--254 nm). In 10 patients undergoing radical gastrectomy for treatment of stomach cancer, CH40 blackened 69% of regional lymph nodes with metastases (38 of 55) and 76% of those nodes without metastases (387 of 512).

Animals↗
PubMed1992

[A comparison of the effects of omeprazole with those of ranitidine on intragastric pH and volume in patients for elective surgeries].

This study compared the effect of omeprazole with those of ranitidine on intragastric secretion during perioperative period. Thirty-one patients were randomly allocated to three groups. Each group received either omeprazole, ranitidine orally or one on the night before surgery. Intragastric pH and volume were measured after induction of anesthesia. Omeprazole group and ranitidine group had a higher mean pH than control group (P less than 0.01). None of the omeprazole group had an aspirate of pH lower than 2.5. One patient (10%) in the ranitidine group and five patients (50%) in the control group and five patients (50%) in the control group had aspirates of pH lower than 2.5. Mean gastric volume was not significantly different among these groups. A single dose of omeprazole 20 mg significantly decreased the number of patients at risk of aspiration pneumonitis.

Gastric Acid↗
PubMed1991

One-step purification of Escherichia coli H(+)-ATPase (F0F1) and its reconstitution into liposomes with neurotransmitter transporters.

About 30% of the protein in the inner membrane of Escherichia coli strain DK8/pBWU13 is H(+)-ATPase (F0F1), and practically homogeneous F0F1 could be obtained by gradient centrifugation after solubilization of these membranes. The recombinant plasmid pBWU13 carries the unc operon for F0F1. When reconstituted into liposomes, F0F1 formed an ATP-dependent proton gradient and membrane potential. Proteoliposomes reconstituted with F0F1 and solubilized transporters from chromaffin granules or synaptic vesicle membranes could transport serotonin, dopamine, and norepinephrine dependent on ATP hydrolysis. F0F1 can be obtained rapidly from DK8/pBWU13, and its reconstitution into liposomes with transporters may be useful for monitoring these transporters during their purification.

Adrenal Medulla↗
PubMed1991

Mutations in Ser174 and the glycine-rich sequence (Gly149, Gly150, and Thr156) in the beta subunit of Escherichia coli H(+)-ATPase.

A sequence motif in the beta subunit of Escherichia coli F1 (Gly-Gly-Ala-Gly-Val-Gly-Lys-Thr, residue 149-156, where conserved residues are underlined) is one of the glycine-rich sequences found in many nucleotide binding proteins. In this study, we constructed a plasmid carrying all the F0F1 genes. This plasmid gave the highest membrane ATPase activity so far reported. Substitution of beta Gly149 by Ser suppressed the effect of the beta Ser174----Phe mutation (defective H(+)-ATPase), but beta Gly150----Ser substitution did not have this effect. A single mutation (beta Gly149----Ser or beta Gly150----Ser) gave active enzyme with altered divalent cation dependency and azide sensitivity: the beta Gly149----Ser mutant enzyme had 100-fold lower azide sensitivity and essentially no Ca(2+)-dependent activity, but had the wild-type level of Mg(2+)-dependent activity with active oxidative phosphorylation. Introduction of a beta Gly149----Ser or beta Gly150----Ser mutation with the beta Ser174----Phe mutation also lowered the Ca(2+)-dependent activity and azide sensitivity. Consistent with our previous findings (Takeyama, M., Ihara, K., Moriyama, Y., Noumi, T., Ida, K., Tomioka, N., Itai, A., Maeda, M., and Futai, M. (1990) J. Biol. Chem. 265, 21279-21284), a beta Thr156----Ala or Cys mutation impaired ATPase activity, suggesting that the hydroxyl moiety at position 156 is essential for the catalytic activity. The possible location of the catalytic site including divalent cation binding site(s) is discussed.

Amino Acid Sequence↗
PubMed1991

Two genes, atpC1 and atpC2, for the gamma subunit of Arabidopsis thaliana chloroplast ATP synthase.

Arabidopsis thaliana has two genes (atpC1, atpC2) coding for gamma subunits of chloroplast ATP synthase. The atpC1 and atpC2 were cloned and sequenced. They had no introns within the reading frames and coded for proteins of 373 and 386 amino acid residues, respectively, including putative transit sequences (50 and 60 amino acid residues, respectively). In contrast, the spinach gamma subunit gene had two introns within the reading frame. The mature sequences coded by the two genes of A. thaliana (atpC1, 323 residues; atpC2, 326 residues) were homologous with that of spinach (J. Miki, M. Maeda, Y. Mukohata, and M. Futai (1988) FEBS Lett. 232, 221-226): the homologies of gamma subunits coded by atpC1 and atpC2 were 72%, those of the subunits coded by atpC1 and spinach cDNA were 84%, and those of the proteins coded by atpC2 and spinach cDNA were 71%. Like the spinach subunit, the gamma subunits coded by the two genes had unique regulatory domains not found in mitochondrial or bacterial subunits. Poly(A)+ mRNAs corresponding to atpC1 (1.5 kilobases) and atpC2 (2.5 kilobases) were detected in illuminated plants, the amount of the former being at least 140 times that of the latter. The atpC1 mRNA was not found in dark-adapted plants. Nuclear protein(s) specifically bound to the upstream region of atpC1 was detected by gel shift assay and its binding was shown to be inhibited by the GT-1 element of the gene encoding the ribulose-1,5-bisphosphate carboxylase small subunit, which is expressed under illumination (P. J. Green, S. A. Kay, and N. H. Chau (1987) EMBO J. 6, 2543-2549). Consistent with these findings, an increased amount of the gamma subunit was detected immunochemically in illuminated plants.

Amino Acid Sequence↗
PubMed1991

Role of Ca2+ influx in bombesin-induced mitogenesis in Swiss 3T3 fibroblasts.

In Swiss 3T3 fibroblasts a peptide mitogen bombesin, which acts through the phospholipase C-protein kinase C signaling pathway, stimulates DNA synthesis in a manner strictly dependent on the medium calcium concentration: [3H]thymidine incorporation into DNA in the presence of a saturating concentration of bombesin (10(-8) M) is 4-fold greater at 3.0 mM extracellular calcium as compared with a value obtained at 0.03 mM calcium. In the present study we attempted to identify the site and the mechanism of action of Ca2+ influx along the bombesin-induced mitogenic signaling pathway, by comparing bombesin effects at 0.03 and 3.0 mM of medium calcium. Bombesin induces the same extent of increases in [3H]inositol phosphates after 1 min, and comparable sustained increases in the cellular content of 1,2-diacylglycerol for up to 4 h, at either 0.03 or 3.0 mM calcium. Bombesin induces the same extent of phosphorylation of MARCKS protein, the major cellular substrate for protein kinase C, irrespective of the medium calcium concentration for at least 4 h. Moreover, diverse cellular responses elicited by bombesin, including c-fos expression, activation of microtubule-associated protein 2 kinase and S6 kinase, glucose uptake, and protein synthesis but not the release of arachidonic acid and its metabolites, are induced similarly at either 0.03 or 3.0 mM calcium. Down-regulation of cellular protein kinase C nearly completely abolishes bombesin effects on c-fos expression, S6 kinase activation, glucose uptake, and DNA synthesis. These results suggest that the target of Ca2+ influx in bombesin-induced mitogenic signaling pathway is not located along the phospholipase C-protein kinase C signal transduction system including cellular events in early G1 phase that exist downstream to protein kinase C action.

Animals↗
PubMed1991

Predominant and developmentally regulated expression of dynamin in neurons.

We have cloned a cDNA for dynamin, a 100 kd microtubule-associated motor protein whose 5' region contains a GTP-binding motif homologous to that of the Mx proteins, from a rat brain library and analyzed its expression. Dynamin mRNA is 3.6 kb and is preferentially expressed in the brain after postnatal day 7, parallel to the developmental increase of the protein. In situ hybridization revealed high levels of dynamin transcripts in neural cells in the cerebellar cortex, hippocampus (particularly in the CA3 area), and cerebral cortex. The transcripts appeared in cerebellar granular cells only after they had ceased dividing and had migrated to the inner granular layer. We show that dynamin is expressed predominantly in neural cells after elongation of their processes, suggesting a role especially in mature neurons.

Adrenal Gland Neoplasms↗
PubMed1991

Selective distribution of aclarubicin to regional lymph nodes with a new dosage form: aclarubicin adsorbed on activated carbon particles.

A new dosage form (ACR-CH) comprising aclarubicin adsorbed on activated carbon particles was designed to sustain release of aclarubicin. ACR-CH or aclarubicin aqueous solution (ACR-sol) was injected subcutaneously into the fore foot-pads of rats. ACR-CH distributed a statistically significantly higher level of aclarubicin to the axillary lymph nodes (detectable up to 7 days after injection) than aclarubicin distributed in an ACR-sol (not detectable after 48 h). To other tissues, ACR-CH distributed statistically significantly low levels of aclarubicin, as compared with ACR-sol.

Aclarubicin↗
PubMed1991

A new dosage form comprising a suspension of activated carbon particles adsorbing aclarubicin: toxicity in mice.

A new dosage form (ACR-CH), a suspension of small activated carbon particles adsorbing aclarubicin, was studied for its toxicity and histopathological effects on organs in mice. The 50% lethal subcutaneous dose of ACR-CH was 83.5 mg/kg, a value 2.42 times that (34.5 mg/kg) of the aclarubicin aqueous solution. The duration of the toxic effects of ACR-CH was prolonged compared with that of the aclarubicin aqueous solution. On autopsy there was no remarkable difference in macroscopic and microscopic examinations between the two dosage forms.

Aclarubicin↗
PubMed1991

Detection and typing of multiple genital human papillomaviruses by DNA amplification with consensus primers.

Many types of human papillomavirus (HPV) are associated with genital lesions. In order to develop simple and sensitive diagnostic procedures for HPV infection, we took advantage of the polymerase chain reaction (PCR). We compared the published nucleotide sequences of the L1 region from six genital HPV types and designed a pair of consensus primers for L1 region. The PCR with the consensus primers for L1 region (L1-PCR) could amplify at least nine genital HPV types, 6, 11, 16, 18, 31, 33, 42, 52 and 58, and the amplified HPV DNA could be typed by subsequent restriction mapping. L1-PCR was compared to Southern blot analysis and also to the consensus primer-mediated PCR for E6 region (E6-PCR) described before. Although both our PCR systems are nonradioactive, PCR for E6 region (E6-PCR) described before. Although both our PCR systems are nonradioactive, the sensitivity in detecting HPV DNA was even better than that obtained by using Southern blot analysis. By means of the PCR systems we detected HPV DNA in 100% of cervical condylomas (10/10), 92% of cervical intraepithelial neoplasias (33/36) and 96% of invasive cervical carcinomas (53/55), while we detected HPV DNA in 12% of normal cervices (12/102).

Base Sequence↗
PubMed1991

Epigenetic control of tumor cell morphology.

XC cell line derived from a single rat cell transformed by the Prague strain of Rous sarcoma virus produced morphologically different colonies. Among them, two distinct cell types consisting of thick, fusiform cells (L-type), and of flat, polygonal cells (R-type) were apparent. By repeated subclonings, pure cultures, L1 and R1, respectively, were obtained. These clones underwent morphological conversion during prolonged culture; L-type colonies appeared in the R-type clone and vice versa. The kinetic curve suggested that the conversion was multi-stepped. When inoculated into nude mice, L-type cells produced much larger tumors at a higher frequency than R-type cells, and the tumors induced by these two clones were histologically different. The expression of v-src gene was higher in L-type than in R-type cells at both mRNA and protein levels.

Actins↗
PubMed1991

Analysis of Moloney murine leukemia virus revertants mutated at the gag-pol junction.

Among Moloney murine leukemia viruses (Mo-MuLVs) having stop codons other than UAG at the gag-pol junction, Mo-MuLV with UAA, but not with UGA, had a replication disadvantage. Mo-MuLV with a glutamine codon (CAG) at the junction did not replicate. A revertant of this virus consisted of the original virus and a virus with a deletion of the pol region. Protease and Pr65gag encoded by their respective genomes complemented each other.

3T3 Cells↗
PubMed1991

[Toxic reduction and superior therapeutic effects on peritoneal carcinomatosis of etoposide particles suspended in oil in mice].

Two dosage forms of etoposide diluted by saline solution (Etp-sol) and etoposide particles suspended in oil (Etp-oil) were examined for the toxicity and therapeutic effects when injected intraperitoneally (ip) in mice. The 50% lethal dose (LD50) values for two weeks observation were 135 mg/kg in Etp-oil and 108 mg/kg in Etp-sol. Two days after intraperitoneal transplantation of 10(6) cells/mouse of P388 leukemia to CDF1 male mice, etoposide was injected intraperitoneally in the form of Etp-oil or Etp-sol. In the mice receiving 20mg/kg of etoposide, 11 of 19 mice given Etp-oil and 3 of 20 given Etp-sol survived to day 60. In the mice receiving 80 mg/kg of etoposide, 1 in 20 treated with Etp-oil and 8 of 20 treated with Etp-sol died from by the toxicity.

Animals↗
PubMed1991

Enhanced anti-cancer efficacy on lymph node metastasis using peplomycin adsorbed on small activated carbon particles.

A new dosage form (PEP-CH) of peplomycin was tested for therapeutic efficacy against lymph node metastasis in mice. PEP-CH is a suspension comprising 4 mg/ml of activated carbon, 2 mg/ml of peplomycin and 1.6 mg/ml of polyvinylpyrrolidone in saline. Mice were subcutaneously inoculated with 3 x 10(5) MH134 tumor cells into the left hind paw. Drugs were given on day 10 when cancer had been metastasized in the left popliteal lymph node. Mice were killed on day 17 and the left popliteal lymph node and the left deep inguinal lymph node were extirpated. Since the degree of the metastatic lesion and the lymph node weight correlated with a statistically high probability with each other, the degree of metastatic lesion was evaluated through comparison of lymph node weight. The left popliteal lymph node and the deep inguinal lymph node were 10.5 mg and 4.5 mg in average weight, respectively, in the mice given PEP-CH containing 0.1 mg of peplomycin subcutaneously into the left hind foot-pad. The weights were significantly smaller than those in the mice given an identical dose of peplomycin aqueous solution subcutaneously into the left hind foot-pad or intraperitoneally.

Adsorption↗