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S Nishimatsu

Publications and source records attributed to S Nishimatsu.

16 recordsLinked to original sources
PubMed1992

A carboxyl-terminal truncated version of the activin receptor mediates activin signals in early Xenopus embryos.

The function of a carboxyl-terminal truncated version of the Xenopus activin receptor, encoded by a previously isolated gene XSTK2, was investigated in early embryos. The transcript corresponding to the truncated receptor gene was detected throughout embryonic development although the temporal expression pattern was different from that of an intact receptor. Injection of XSTK2 mRNA into early embryos resulted in the formation of a duplicated body axis. Mesoderm induction as evaluated by the activation of the alpha-actin gene in presumptive ectoderm (animal cap) treated with exogenous activin was significantly enhanced by the injection of XSTK2 mRNA. These results suggest that the truncated receptor is capable of transmitting the activin signal to the same extent as the native receptor.

Actins↗
PubMed1992

Genes for bone morphogenetic proteins are differentially transcribed in early amphibian embryos.

We have previously demonstrated that activin, a member of the TGF-beta family, has a potent mesoderm-inducing activity in Xenopus embryos. In the course of screening for activin-related genes from Xenopus, we have cloned cDNAs for Xenopus homologue of BMP-2, -4 and -7. Northern blot analysis revealed that these BMP genes are maternally encoded and differentially regulated after fertilization. Alkaline phosphatase-inducing assay using the recombinant BMP proteins has shown that at least BMP-2 and -4 have similar activity to mammalian counterparts.

Alkaline Phosphatase↗
PubMed1992

Multiple genes for Xenopus activin receptor expressed during early embryogenesis.

Four distinct cDNAs for activin receptor designated as XSTK2, 3, 8 and 9 have been cloned from a Xenopus laevis cDNA library. The protein structures deduced from the cDNAs have shown that they all have a putative extracellular ligand-binding domain, a single transmembrane domain and cytoplasmic Ser/Thr kinase domain, except that XSTK2 is extremely similar to the XSTK3 gene but lacks a carboxyl-terminal part of the kinase motif. Northern blot analysis showed that all transcripts are maternally inherited. The levels of transcript for XSTK2, 3 and 8 appeared to fluctuate during early development while those for XSTK9 maintain constant.

Activin Receptors↗
PubMed1992

Expression of thymosin beta 4 gene during Xenopus laevis embryogenesis.

In order to investigate the molecular events which take place during gastrulation, extracts from developing Xenopus embryos were analyzed for temporal peptide distribution by high performance liquid chromatography. One peptide peak which became increasingly dominant after gastrulation was purified and partially characterized. The amino acid sequence of enzymic digests showed the peptide is extremely similar to mammalian thymosin beta 4. The peptide was capable of binding actin monomers like mammalian counterparts. Cloning of the Xenopus thymosin beta 4 cDNA showed that only three amino acid substitutions occurred between amphibian and bovine. Northern blot analysis revealed the mRNA is maternally present at a low level and the transcript becomes abundant after gastrulation, supporting the distribution of the peptide.

Amino Acid Sequence↗
PubMed1992

Identification of bone morphogenetic protein-2 in early Xenopus laevis embryos.

Polyclonal antibodies capable of reacting with amphibian bone morphogenetic protein (BMP-2 and -4) were raised in rabbits by immunization with a synthetic 21 amino acid peptide which corresponds to a sequence residing in the mature protein of Xenopus BMP-2 (xBMP-2). The antibodies recognized an embryonic BMP as well as mammalian and bacteria expressed recombinant xBMPs. The antibodies detected, under reducing conditions, a 30 kDa protein in the extract of oocytes and embryos during early development. Interestingly, acidification of the extract from each developmental stage yielded a protein band of smaller molecular weight of 18 kDa, which is similar in size to reduced form of mature BMPs purified from mammalian species. Two-dimensional electrophoresis employed to examine the molecular weight of unreduced forms using the antibody, revealed that both molecular forms are monomeric in the embryos. The result suggests that at least BMP-2 mRNA previously detected in early embryos, is translated into peptide but the dimerization may be incomplete or strictly limited in these embryos.

Amino Acid Sequence↗
PubMed1991

Presence of activin (erythroid differentiation factor) in unfertilized eggs and blastulae of Xenopus laevis.

Activin A, a member of the transforming growth factor beta superfamily, has recently been found to have potent mesoderm-inducing activity on isolated early Xenopus animal-cap cells. We measured the activin activity of the Xenopus egg extract by using an erythroid-differentiating test with Friend leukemia cells. The results showed that an activin homologue is, indeed, contained in unfertilized eggs and blastulae of Xenopus laevis in a considerable amount. This activity was eluted at the same retention time as human activin A when fractionated by reversed-phase HPLC. Furthermore, the fraction containing erythroid-differentiating factor activity had mesoderm-inducing activity on Xenopus animal-cap cells. The mesoderm-inducing activity of this fraction was suppressed when coincubated with follistatin, an activin-binding protein. These results suggest that an endogenous activin may be a natural mesoderm-inducing factor acting in Xenopus embryogenesis.

Activins↗
PubMed1991

Changes of serum bilirubin fraction in postoperative liver failure cases treated by plasmapheresis: an effective marker for evaluation of bilirubin removal.

Utility of a new method of bilirubin fractionation was evaluated in monitoring the effectiveness of plasma exchange (PE) performed in 10 postoperative cases with liver failure. Fractionation of serum bilirubin by high-performance liquid chromatography demonstrated a higher delta bilirubin (B delta) peak against lower conjugated bilirubin peaks [monoconjugated bilirubin (MCB) and diconjugated bilirubin (DCB)] in the three recovered cases. The calculated ratio of MCB/B delta and the ratio of B delta/(MCB + DCB + B delta) in the recovered cases showed statistically significant different against seven unrecovered cases (p less than 0.01). These results suggest that the recovered cases had a different quality hyperbilirubinemia and a different disease entity before PE as well as a different response to PE, and this novel method for serum bilirubin subfraction is considered a useful marker in selecting a patient responsive to PE.

Aged↗
PubMed1990

Activin as a cell differentiation factor.

Activin, originally discovered as a polypeptide hormone that is capable of stimulating follicle-stimulating hormone secretion from pituitary cells in vitro, has recently been found to have a much wider range of biological activities. There are a number of reports of activin action as a cell differentiation factor on various types of cells rather than as a modulator of hormone secretion, as predicted initially, based on its structural similarity to transforming growth factor-beta. Studies of the distribution of activin and its receptor in a variety of tissues and its wide-ranging actions clearly illustrates its multifunctional properties. In particular, activin has been shown to be a potential regulator of early development of Xenopus laevis. Observation of activin effect in embryogenesis is of general importance to our understanding of the role of the family of growth factors in developmental processes.

Activin Receptors↗
PubMed1986

Human renin gene of renin-secreting tumor.

A large amount of renin mRNA was found to be expressed in the juxtaglomerular cell (JGC) tumor, as determined by Northern analysis. We have isolated the long 5'-flanking region of the human renin gene from the tumor, and characterized the promoter region with respect to nucleotide (nt) sequence and mRNA transcription start point. Of two sets of CAAT and TATA box at 29 bp upstream from the capping site is demonstrated to be a functional promoter by the primer extension. The 1:6-kb sequence, containing the 5'-flanking region, exon 1, and part of the first intron, obtained from the tumor was in complete agreement with that of the clone from fetal liver, which does not produce renin. This indicates that abnormal expression of the human renin gene in the JGC tumor involves no major alteration in the primary structure within 1.2 kb of the 5'-flanking region. Within 1.2 kb of the 5'-flanking region, there are several nt segments exhibiting homology with the glucocorticoid, estrogen, and progesterone receptor-binding sites and enhancers. These structures may be related to the tissue-specific expression of the renin gene.

Amino Acid Sequence↗
PubMedDate not supplied

Therapeutic plasmapheresis for liver failure after hepatectomy.

Therapeutic plasmapheresis (PP) for liver failure following the resection of primary liver cancer was evaluated retrospectively. PP was repeated two to three times per week using plasma exchange (PE) with fresh frozen plasma as a substitution fluid in all eight cases and direct hemoperfusion (DHP) in two cases. PE effectively decreased serum bilirubin and/or improved hepatic encephalopathy in six of eight patients and prolonged survival time (p less than 0.05, chi-square test). DHP was not effective. Liver failure following the resection of damaged liver differs from acute liver failure in both the condition itself and the reaction to PP. Fractionation of serum bilirubin using high performance liquid chromatography showed differences in the ratio of delta bilirubin in one survivor versus two who died and was effective in selecting a patient who would respond to PE. In conclusion, PE is effective in prolonging survival time after liver failure in hepatectomized patients compared to conventional therapy.

Bilirubin↗
PubMedDate not supplied

Effects of nucleosides and a nucleotide on DNA and RNA syntheses by the salvage and de novo pathway in primary monolayer cultures of hepatocytes and hepatoma cells.

Studies were made on the effects of inosine, guanosine 5'-monophosphate (GMP), cytidine, uridine, thymidine, and their mixture (4:4:4:3:1, OG-VI) on DNA and RNA syntheses in primary monolayer cultures of normal hepatocytes and cultures of hepatoma cells, AH130, to use these compounds for total parenteral nutrition. Addition of an appropriate amount of inosine, GMP, uridine, or thymidine to primary cultures of hepatocytes enhanced both DNA and RNA syntheses by the salvage and de novo pathways. Cytidine appeared to have lower optimal concentration for enhancing these pathways. The OG-VI mixture also enhanced the syntheses of DNA and RNA, but the composition of the mixture was not optimal. Additions of inosine, GMP, uridine, and thymidine to cultured hepatoma cells also enhanced their DNA and RNA syntheses, but the cells consumed more of the added nucleic acid compounds than hepatocytes did. Addition of cytidine had no effect on proliferation of the cells. The OG-VI mixture at relatively higher concentration inhibited the syntheses of DNA and RNA by hepatoma cells. Addition of high concentrations of nucleic acid compounds was found to suppress the proliferation of both hepatocytes and hepatoma cells. These results suggest that addition of optimal amounts of nucleic acid compounds such as nucleosides and nucleotides would enhance growth of hepatocytes, particularly during liver regeneration, but that they may also enhance proliferation of tumor cells in the liver.

Animals↗
PubMedDate not supplied

Effect of methionine-deprived nutrition on cell growth and cell kinetics in cell cultures and experimental tumors.

The effect of methionine-deprived nutrition on cell growth and cell kinetics was investigated in cell cultures and in tumor-bearing rats using the total parenteral nutrition (TPN) technique. A simultaneous flow cytometric measurement of the cellular DNA content and the amount of 5-bromodeoxyuridine incorporated into cellular DNA was performed for analysis of cell kinetics. The methionine-free medium demonstrated a cytocidal effect on the growth of SLC cells after 6 hours of culturing. It decreased viability from 80% in the control medium to 23%, and it decreased the S phase and increased the G0/G1 phase of the cell cycles. The methionine-deprived medium showed a concentration-dependent inhibition in cellular growth. Methionine-deprived TPN was seen to inhibit AH109A and SLC tumor growth compared with conventional TPN and decreased the S phase and increased the G0/G1 phase of cell cycles. These results confirm that methionine deprivation blocks cells from processing into the G1 phase and recycling, and that it is effective in inhibiting tumor growth in cultures and in vivo.

Animals↗