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S Ichihara

Publications and source records attributed to S Ichihara.

At least 73 records · Page 4Linked to original sources
PubMed1989

Relationship between the extent of intraductal component and that of the invasive component in ductal carcinomas of the breast.

To clarify the relationship between the extent of the intraductal component and the invasive component in cases of invasive ductal carcinoma (IDC) of the breast, we divided 87 such cases into two groups, Group I in which the intraductal component extended for less than 10 mm (36 cases) and Group II in which the intraductal component extended for 10 mm or more (51 cases). On histological slides, there was an association between the extent of the intraductal component and the pattern of invasion. The majority (80.6%) of Group I IDC cases showed an invasive component composed of one invasive nodule, whereas 62.7% of Group II IDC cases showed an invasive component composed of two or more such nodules. On gross and microscopical examination, Group II IDC showed a significantly larger mean tumor size than Group I IDC (23.4 +/- 8.9 mm vs. 18.3 +/- 6.6 mm, P less than 0.002 & 24.1 +/- 14.1 mm vs. 17.1 +/- 6.5 mm, P less than 0.002). A similar result was obtained by clinical examination (41.8 +/- 17.0 mm vs. 29.5 +/- 11.6 mm, P less than 0.0001). These results suggest that Group II ductal carcinomas may frequently develop multiple stromal invasion, resulting suddenly in a sizeable breast mass perceived by the patient.

Breast Neoplasms↗
PubMed1989

[A case of retroperitoneal liposarcoma].

We reported a case of retroperitoneal well differentiated liposarcoma, which consisted of lipoma-like type and sclerosing type. The latter was represented as solid density tumor on CT, which was difficult to differentiate from undifferentiated liposarcoma and other soft tissue tumors. Angiographically, ureteral artery developed and became a main feeder.

Aged↗
PubMed1988

Transamination of LTE4 by cysteine conjugate aminotransferase.

Leukotriene E4 (LTE4) was transaminated to 5(S)-hydroxy-6(R)-S-(2-keto-3-thiopropionyl)-7,9-trans-11,14-cis- eicosatetraenoic acid (tentatively designated as LTG4) by cysteine conjugate aminotransferase I purified from rat liver supernatant in the presence of alpha-ketoglutaric acid or alpha-keto-gamma-methiolbutyric acid. The transamination activity was present in the kidney as well as in the liver, but not in the lung or leukocytes.

Animals↗
PubMed1988

Purification and characterization of a signal peptide, a product of protein secretion across the cytoplasmic membrane of Escherichia coli.

A signal peptide, a processing product of the precursor of the lipoprotein in the cytoplasmic membrane of Escherichia coli, has been purified through extractions with butanol and ethyl ether and chromatographies with a Sephadex LH-60 column and Sep-pak C18. Analysis of the amino acid composition and sequencing of the N- and C-termini indicate that the signal peptide was intact, suggesting that the first step of the signal peptide catabolism in the cytoplasmic membrane is the cleavage of the intact signal peptide. During the purification, the signal peptide exhibited unique features, including strong interaction with phospholipids. The possible importance of such features in the process of protein translocation across membranes is discussed.

Amino Acids↗
PubMed1988

Determination of 5-fluorouracil in plasma and liver after oral administration of 5'-deoxy-5-fluorouridine using gas chromatography-mass spectrometry.

A method for determination of 5-fluorouracil (5-FU) has been established for pharmacokinetic study of 5'-deoxy-5-fluorouridine (5'-DFUR), a newly developed prodrug of 5-FU. 5-FU was extracted with diethyl-ether containing 1-propanol and methylated with CH3I in the presence of (CH3)4NOH. The methylated 5-FU was analyzed by gas chromatography-mass spectrometry using 15N2-5-FU as an internal standard. Quantitation was carried out by selected-ion monitoring of molecular ions of N,N-dimethyl-5-FU (m/z 158) and the internal standard (m/z 160). The sensitivity (greater than 2 ng/g sample), specificity and precision of the method were satisfactory for application to clinical studies of this drug. After an oral administration of 5'-DFUR (800 mg/body) to patients with cancer, 5-FU in plasma peaked within 1 h and eliminated with an apparent half life of about 1 h.

Administration, Oral↗
PubMed1988

Purification and characterization of cysteine conjugate transaminases from rat liver.

1. Soluble cysteine-conjugate alpha-ketoglutarate transaminase (CAT-I) was purified about 670-fold from rat liver cytosol using s-(p-bromophenyl)-L-cysteine as amino acid substrate. The enzyme preparation of the final step of purification showed a single band in polyacrylamide gel electrophoresis. CAT-I accounted for 64% of the transaminase activity in cytosol. 2. The mol. wt of the enzyme was about 64,000 as determined by gel filtration. Respective Km values for s-(p-bromophenyl)-L-cysteine and alpha-ketoglutaric acid were 1.0 and 1.3 mM in Tris-acetate buffer (pH 7.0). Aminooxyacetic acid, hydroxylamine, and KCN inhibited the enzyme activity. 3. In addition to CAT-I, two isozymes (CAT-IIA and CAT-IIB) were partially purified from rat liver cytosol. In respect of mol. wt, substrate specificity towards cysteine conjugates, and several other properties, CAT-IIA and CAT-IIB were very similar to CAT-I. However, differences were observed for these enzymes in the rate of reverse reaction (formation reaction of cysteine conjugates and alpha-ketoglutaric acid) and substrate specificity towards L-aspartic acid and L-cysteinesulphinic acid.

Animals↗
PubMed1988

Involvement of cystathionase in the formation of alkane-thiols from corresponding cysteine conjugates.

1. Rat liver cystathionase [EC.4.4.1.1] mediated a cleavage reaction of the C-S bond of S-alkyl-L-cysteine conjugates to give equimolar amounts of corresponding thiols, ammonia, and pyruvic acid. Neither S-aryl- nor S-aralkyl-L-cysteine conjugates were acceptable substrates. 2. The Km value for S-(tert-butyl)-L-cysteine was 0.3 mM at pH 8.5 in Tris-HCl buffer. 3. The S-alkyl-L-cysteine lyase activity of cystathionase was inhibited with carbonyl reagents and dithiothreitol. 4. The present finding that cystathionase has activity towards cysteine conjugates may provide some insights into the role of this enzyme in the metabolism of xenobiotics.

Alkanes↗
PubMed1987

Processing of a plant vacuolar protein precursor in vitro.

A precursor for sporamin A, the storage protein of the tuberous roots of sweet potato deposited in the vacuole, is synthesized on membrane-bound polysomes and has an extra peptide of 37 amino acids at the N-terminus of the mature form, which can be divided into an N-terminal putative signal peptide sequence (residues -37 to -17) and a segment enriched with charged amino acids (residues -16 to -1) [Hattori, T., et al. (1985) Plant Mol. Biol. 5, 313-320]. We examined the in vitro processing of the sporamin A precursor using a messenger RNA derived from a full-length cDNA by the SP6 transcription system. When the in vitro translation in a wheat germ cell-free system was carried out in the presence of dog pancreas microsomal membranes, the precursor polypeptide (Mr = 24,000) was processed into an intermediate form still larger than the mature polypeptide (Mr = 20,000). The processed intermediate form was also produced by addition of microsomal membranes from sweet potato and potato in the translation reaction, although less efficiently compared to dog membranes. Moreover, Escherichia coli cells expressing sporamin precursor accumulated a polypeptide with the same electrophoretic mobility as the intermediate form produced in vitro. The processing by dog membranes is accompanied by translocation of the polypeptide across the membranes as assayed by resistance to externally added proteases. The N-terminal amino acid sequencing analysis of [3H]leucine-labelled intermediate form produced in vitro by dog membranes indicated that co-translational processing of the sporamin precursor by endoplasmic reticulum membranes removes only the signal peptide segment from the extra peptide, and suggested that the charged segment following the signal peptide is removed post-translationally during the transport of sporamin into vacuole. The significance of two-step processing of plant vacuolar protein precursor is discussed in relation to the two-step processing of precursors for yeast vacuolar proteins and animal lysosomal proteins.

Animals↗
PubMed1987

Purification and properties of methyl sulfoxide reductases from rat kidney.

Two kinds of enzymes (tentatively designated methyl sulfoxide reductases I and II) responsible for the reduction of the methyl sulfoxide group on various xenobiotics have been purified about 223- and 155-fold, respectively, from rat kidney cytosol. The molecular weight was determined to be 12,000 +/- 1000 for methyl sulfoxide reductase I and 24,000 +/- 1000 for methyl sulfoxide reductase II. Thioredoxin or dithiothreitol is essential in order for the reducing activity to occur. The respective Km values of p-bromophenylmethyl sulfoxide were 2.75 and 1.30 mM for methyl sulfoxide reductases I and II. Replacement of the methyl group on the sulfur atom with a longer alkyl group or phenyl group caused a markedly low or negligible substrate activity.

Animals↗
PubMed1987

In vitro translocation of protein across Escherichia coli membrane vesicles requires both the proton motive force and ATP.

The energy requirement for protein translocation across membrane was studied with inverted membrane vesicles from an Escherichia coli strain that lacks all components of F1F0-ATPase. An ompF-lpp chimeric protein was used as a model secretory protein. Translocation of the chimeric protein into membrane vesicles was totally inhibited in the presence of carbonyl cyanide m-chlorophenylhydrazone (CCCP) or valinomycin and nigericin and partially inhibited when either valinomycin or nigericin alone was added. Depletion of ATP with glucose and hexokinase resulted in the complete inhibition of the translocation process, and the inhibition was suppressed by the addition of ATP-generating systems such as phosphoenolpyruvate-pyruvate kinase or creatine phosphate-creatine kinase. These results indicate that both the proton motive force and ATP are required for the translocation process. The results further suggest that both the membrane potential and the chemical gradient of protons (delta pH), of which the proton motive force is composed, participate in the translocation process.

Adenosine Triphosphate↗
PubMed1987

Characterization of the sppA gene coding for protease IV, a signal peptide peptidase of Escherichia coli.

The sppA gene codes for protease IV, a signal peptide peptidase of Escherichia coli. Using the gene cloned on a plasmid, we constructed an E. coli strain carrying the ampicillin resistance gene near the chromosomal sppA gene and an sppA deletion strain in which the deleted portion was replaced by the kanamycin resistance gene. Using these strains, we mapped the sppA gene at 38.5 min on the chromosome, the gene order being katE-xthA-sppA-pncA. Although digestion of the signal peptide that accumulated in the cell envelope fraction was considerably slower in the deletion mutant than in the sppA+ strain, it was still significant, suggesting the participation of another envelope protease(s) in signal peptide digestion.

Chromosome Deletion↗
PubMed1987

[Futraful and UFT, their metabolic characteristics].

Investigations were made in human on the metabolism of Futraful (FT) and UFT (combination of uracil and FT), both of which are anticancer agents of pyrimidine metabolism antagonist. As a result, it was demonstrated that from the metabolic view point, those drugs essentially have a tumor-selective toxicity. Next, the mechanism of the superior clinical anticancer effect of UFT, compared to FT, was investigated enzymatically, showing the inhibitory effect of uracil on the degradation of 5-fluorouracil generated from FT in the organs and tumor tissues. Discussions were also made for the further development of fluoropyrimidines.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1986

Involvement of leukocytes in the oxygenation and chlorination reaction of phenylbutazone.

A center carbon atom of 1,3-diketone moiety of phenylbutazone was oxidized to give three metabolites--4-hydroxyphenylbutazone (metabolite I), 4-hydroperoxyphenylbutazone (metabolite II) and 4-chlorophenylbutazone (metabolite III)--by the action of enzymes present in leukocyte extract obtained from peritoneal exudate of rats. Both metabolites II and III were produced by peroxidases, while metabolite I was produced by enzymes other than the peroxidases.

Animals↗
PubMed1986

Purification and characterization of the OmpR protein, a positive regulator involved in osmoregulatory expression of the ompF and ompC genes in Escherichia coli.

The OmpR protein is a positive regulator involved in osmoregulatory expression of the ompF and ompC genes, which respectively code for major outer membrane proteins OmpF and OmpC of Escherichia coli. The OmpR protein has been purified to homogeneity from an overproducing strain harboring an ompR gene-carrying plasmid. Throughout the purification the OmpR protein behaved as a single entity. The molecular weight determined on sodium dodecyl sulfate-polyacrylamide gel, the total amino acid composition, and the NH2-terminal amino acid sequence of the purified protein were essentially the same as those deduced from the nucleotide sequence of the ompR gene. Molecular weight determination and cross-linking study on the native protein revealed that the purified protein exists as a monomer. The purified OmpR protein was specifically bound to the promoter regions of the ompC and ompF genes. Experiments with a series of upstream deletions of the ompC and ompF promoters revealed that the region upstream from the -35 region was indispensable for OmpR binding to both the ompC and the ompF promoters. Although it has been proposed that depending on the medium osmolarity the OmpR protein may exist in two alternative structures, which respectively regulate functioning of the ompC and the ompF promoters, the purified OmpR protein appeared to be homogeneous and interacted with both promoters to the same extent.

Amino Acids↗
PubMed1986

Molecular cloning and sequencing of the sppA gene and characterization of the encoded protease IV, a signal peptide peptidase, of Escherichia coli.

Clones carrying a gene causing overproduction of protease IV, a signal peptide peptidase of Escherichia coli, were isolated from the Clarke and Carbon's collection. Restriction mapping analysis revealed that pLC7-10 and pLC40-13, thus isolated, shared the same chromosomal DNA region. The 2.3-kilobase RsaI-SalI fragment in this region, which was found to carry the gene, was subjected to nucleotide sequence determination. Only one long open reading frame was found. The hypothetical polypeptide sequence deduced from the DNA sequence has a molecular mass of 67,241 daltons. The putative gene was named sppA. Protease IV was purified to homogeneity from the cytoplasmic membrane of an overproducing strain harboring a sppA gene-carrying plasmid. The purified enzyme gave a single polypeptide band of 67,000-dalton molecular mass on sodium dodecyl sulfate-polyacrylamide gel. This molecular mass and the amino acid composition of the purified enzyme were consistent with the deduced primary structure of the sppA gene product. The molecular mass thus determined was almost twice as large as that previously reported by Pacaud (Pacaud, M. (1982) J. Biol. Chem. 257, 4333-4339). A cross-linking study revealed that protease IV is a tetramer of the polypeptide. From these results, we conclude that protease IV is a tetramer of the sppA gene product.

Amino Acids↗