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S Natori

Publications and source records attributed to S Natori.

At least 163 records · Page 9Linked to original sources
PubMed1992

The 29-kDa hemocyte proteinase dissociates fat body at metamorphosis of Sarcophaga.

Previously, we reported the purification of a 29-kDa proteinase from the pupal hemocytes of Sarcophaga peregrina (flesh fly). Antibody against this proteinase was found to inhibit dissociation of the fat body by pupal hemocytes in vitro. Moreover, the purified enzyme alone was shown to dissociate the fat body. This enzyme was found to be localized in granules of heterogeneous size in the hemocytes and to be released on their interaction with the fat body. From these results, we conclude that this 29-kDa proteinase participates in dissociation of the fat body at metamorphosis.

Animals↗
PubMed1992

Inhibitory effects of plant secondary metabolites on cytotoxic activity of polymorphonuclear leucocytes.

The inhibitory effects of 151 natural products, representing most of the frequently occurring types, on the cytotoxicity to MM2 tumor cells of polymorphonuclear leucocytes (PMN) induced by TAK, a polysaccharide immunomodulator, were examined. Forty-two compounds inhibited the TAK-induced activation of PMN. Among them, some naturally occurring quinones and various alkaloids (nicotine, Cinchona alkaloids, isoquinoline alkaloids such as cepharanthine, and indole alkaloids such as ajmaline) exhibited potent inhibitory effects. Using the inhibition assay for monitoring, the extracts of Hydrangea Dulcis folium, Scopoliae rhizoma, Cinchona cortex, Magnoliae cortex, Stephania tuber, and Rauwolfia radix were analysed to characterize the active constituents.

Animals↗
PubMed1992

Decrease by psychotropic drugs and local anaesthetics of membrane fluidity measured by fluorescence anisotropy in Escherichia coli.

The effects of psychotropic drugs and local anaesthetics on the fluidity of Escherichia coli cell membranes were examined. Chlorpromazine was shown to increase 1,6-diphenyl-1,3,5-hexatriene fluorescence anisotropy, indicating that it decreased the membrane fluidity. This increase was significant at a temperature of more than 24 degrees C. Dibucaine, lignocaine, imipramine, tetracaine and procaine also increased the fluorescence anisotropy.

Anesthetics, Local↗
PubMed1992

Purification and localization of p10, a novel protein that increases in nymphal regenerating legs of Periplaneta americana (American cockroach).

Content of a protein with a molecular mass of 10 kDa (p10) was found to increase significantly in regenerating legs of the American cockroach (Periplaneta americana). This protein was purified to homogeneity from a homogenate of regenerating legs. Partial amino acid sequencing indicated that p10 is a novel protein. Immunoblotting showed that its content in regenerating legs was 30 times that in normal legs, and decreased significantly when leg regeneration was complete. An immunofluorescence study revealed that p10 localizes exclusively on the external side of newly formed epidermis of regenerating legs.

Amino Acid Sequence↗
PubMed1991

Binding of simian virus 40 large tumor antigen to phospholipid vesicles.

SV40 T antigen is the initiator protein of SV40 DNA replication. We examined the interaction of purified SV40 T antigen with phospholipids by (i) centrifugation analysis with phospholipid vesicles, (ii) filter binding assay and footprint analysis of T antigen binding to the replication origin of SV40 DNA and (iii) analysis of the initiation of SV40 DNA replication in vitro. In all cases, cardiolipin showed affinity for T antigen and inhibited its DNA binding capacity. Phosphatidylglycerol with unsaturated fatty acids also inhibited the binding of T antigen to the replication origin of SV40 DNA, whereas phosphatidylglycerol with saturated fatty acids did not. This finding suggested the importance of unsaturated fatty acids for the interaction of T antigen with phospholipids. Other phospholipids including phosphatidylserine, phosphatidylinositol and phosphatidylethanolamine showed little or no affinity for T antigen.

Antigens, Polyomavirus Transforming↗
PubMed1991

Involvement of sapecin in embryonic cell proliferation of Sarcophaga peregrina (flesh fly).

Addition of antibodies against sapecin to the culture medium of NIH-Sape-4 cells derived from a Sarcophaga embryo greatly inhibited cell proliferation, whereas addition of sapecin stimulated cell proliferation. These results suggest that sapecin is involved in the proliferation of embryonic cells of Sarcophaga. Sapecin is known to have potent antibacterial activity, so it seems to have two different biological functions: i.e. protection against bacterial infection and stimulation of embryonic cell proliferation.

Animals↗
PubMed1991

A novel mechanism of Sarcophaga lectin gene expression. Possible involvement of oxidation of the sulfhydryl group of a fat-body protein.

The Sarcophaga lectin gene, an acute-phase-responsive protein of Sarcophaga, was found to be activated when the fat body was incubated in phosphate-buffered insect saline (10 mM NaH2PO4/Na2HPO4, pH 6.2, 2 mM NaHCO3, 1 mM MgCl2, 5 mM KCl, 1 mM CaCl2 and 120 mM NaCl). This activation was selectively suppressed by addition of 2-mercaptoethanol. 2-Mercaptoethanol did not affect the transcription directly, suggesting that the oxidation of the sulfhydryl group of a fat-body protein is required for activation of the Sarcophaga lectin gene. This oxidation reaction seemed to occur immediately when the fat body was incubated in vitro, and once this reaction was initiated, 2-mercaptoethanol no longer inhibited transcription of the Sarcophaga lectin gene. This gene is known to be activated when the larval-body wall of Sarcophaga is injured. It is suggested that the Sarcophaga lectin gene is activated via this novel mechanism on its acute-phase expression in vivo.

Animals↗
PubMed1991

Molecular cloning of cDNA for lipopolysaccharide-binding protein from the hemolymph of the American cockroach, Periplaneta americana. Similarity of the protein with animal lectins and its acute phase expression.

A previous paper described the purification of a calcium-dependent lipopolysaccharide-binding protein from the hemolymph of Periplaneta americana (Jomori, T., Kubo, T., and Natori, S. (1990) Eur. J. Biochem. 190, 201-206). This paper describes the molecular cloning and characterization of cDNA for the LPS-binding protein. This protein was found to have a carbohydrate-recognition domain at its carboxyl terminus containing amino acid sequences that are conserved in various mammalian C-type lectins. It was also shown to contain an N-linked carbohydrate chain, and the amino acid residue carrying this chain was assigned as Asn at position 56 (23rd amino acid residue from the amino terminus). Northern blot analysis revealed the presence of multiple mRNAs that hybridized with this cDNA and transient increases in their content after injection of Escherichia coli into adult Periplaneta, suggesting that the LPS-binding protein plays a role in the acute phase response of this insect.

Acute-Phase Proteins↗
PubMed1991

Purification of a stage-specific and sequence-specific DNA-binding protein for the arylphorin gene of Sarcophaga peregrina.

A protein that binds specifically to the nucleotide sequence ACCACAACA located at residues -247 to -255 upstream of the +1 site of the arylphorin gene of Sarcophaga peregrina was purified to homogeneity from fat body nuclei of third instar larvae. This DNA-binding protein consisted of two subunits with molecular masses of 40 kDa and 42 kDa, respectively. Accurate transcription initiation of a truncated arylphorin gene in a nuclear extract of NIH-Sape-4 cells, an embryonic cell line of Sarcophaga, was significantly enhanced in the presence of the purified DNA-binding protein.

Animals↗
PubMed1991

Inhibitory action of phospholipid-interacting drugs on transcription initiation in a nuclear extract of Ehrlich ascites tumor cells.

Drugs with affinity for phospholipids, such as chlorpromazine, verapamil, tetracaine and imipramine, were found to inhibit accurate transcription from adenovirus 2 major late promoter in a nuclear extract of Ehrlich ascites tumor cells. The transcription activity of the nuclear extract inhibited by chlorpromazine was restored by addition of acidic phospholipids. The nuclear extract was also shown to lose transcription activity when treated with phospholipase A2. Chlorpromazine was found to inhibit transcription at the step of initiation, not elongation. Moreover, it did not affect the activity of purified RNA polymerase II, suggesting the interaction of phospholipids with transcription factors in the nuclear extract. Some transcription factors in the nuclear extract were found to have affinity for cardiolipin, and were precipitated with excess cardiolipin. The transcription factors precipitated with cardiolipin could be solubilized with guanidine hydrochloride, and restored the transcription activity of the cardiolipin-treated nuclear extract.

Adenoviruses, Human↗
PubMed1991

Preferential deadenylation of Sarcophaga lectin mRNA during its acute phase expression.

The sizes of mRNAs of various defense proteins of Sarcophaga peregrina (flesh fly) were shown to become progressively shorter. We studied the shortening of the Sarcophaga lectin mRNA, because this mRNA shows acute phase expression on injury of the larvae and programmed expression in the pupal stage. Results showed that this mRNA underwent deadenylation when expressed in response to body injury, but no appreciable change in size during programmed expression in the pupal stage. During acute phase expression, the size of the poly(A) tail of the Sarcophaga lectin mRNA decreased from 130 bases to about 30 bases in 6 h. The half-lives of the forms with different sizes of poly(A) tail were almost identical.

Adenine↗
PubMed1991

Participation of a 200-kDa hemocyte membrane protein in the dissociation of the fat body at the metamorphosis of Sarcophaga.

Three monoclonal antibodies were raised against a 200-kDa protein specifically expressed on the surface of hemocytes when Sarcophaga larvae pupated. One of these antibodies significantly inhibited dissociation of the fat body in the presence of pupal hemocytes, indicating that the 200-kDa protein is essential for dissociation of the fat body by the hemocytes. When the hemocytes were treated with a mixture of the monoclonal antibodies, they were found to secrete a significant amount of chymotrypsin-like proteinase. Moreover, the number of hemocytes expressing the 200-kDa protein increased significantly after puparium formation. These results suggested that some signal is transferred to the hemocytes via the 200-kDa protein when they interact with the basement membrane of the fat body and that this induces their secretion of a chymotrypsin-like proteinase essential for decomposition of the fat body.

Animals↗
PubMed1991

Involvement of Sarcophaga lectin in the development of imaginal discs of Sarcophaga peregrina in an autocrine manner.

The imaginal discs of Sarcophaga were found not to develop normally in the presence of galactose, a hapten sugar of Sarcophaga lectin, or anti-Sarcophaga lectin antibody. Wing and leg discs cultured with these substances became morphologically abnormal and no imaginal discs reached the stage of terminal differentiation, even in the presence of 20-hydroxyecdysone. The development of the imaginal discs was shown to be autonomously regulated in an autocrine manner by Sarcophaga lectin; namely Sarcophaga lectin was secreted by the imaginal discs in the presence of 20-hydroxyecdysone, and the stimulus of self-induced Sarcophaga lectin seemed to be indispensable for further development of the imaginal discs. Sarcophaga lectin was originally found as a defense protein, but these results show that it plays independent roles in both defense and development.

Animals↗
PubMed1991

Cycloleonurinin, a cyclic peptide from Leonuri Fructus.

From Leonuri Fructus, a cyclic peptide composed of twelve amino acid residues was isolated. The sequence of the residues was established by mass spectroscopy and by the use of a protein sequencer for the partial hydrolysates obtained by alpha-chymotrypsin.

Amino Acid Sequence↗
PubMed1991

Localization of regenectin in regenerates of American cockroach (Periplaneta americana) legs.

The localization of regenectin, a sucrose-binding C-type lectin, in the regeneration of the cockroach leg was investigated by immunoblotting and immunofluorescence studies. Regenectin was found to appear transiently around developing muscle cells in regenerating legs in the late stage of regeneration. With maturation of the muscles, it disappeared and was not detectable in completely regenerated legs. These findings suggest that regenectin is a cementing substance connecting developing muscle cells. Regenectin was not detected in embryos or nymphal legs at various developmental stages, suggesting that it might not be involved in normal development of embryos and legs.

Animals↗
PubMed1991

[A case report of idiopathic myxedema with secondary amenorrhoea and hyperprolactinemia: effect of thyroid hormone replacement on reduction of pituitary enlargement and restoration of fertility].

A 37-year old housewife was admitted to our department because of long-standing amenorrhoea and galactorrhoea. After several hormonal examinations, she was proved to be suffered from primary hypothyroidism with hyperprolactinemia. In addition, brain computed tomography (CT) showed the finding of enhanced pituitary enlargement, suggesting pituitary hypertrophy or pituitary adenoma. Based on some therapeutic experiences in similar cases in several reports, we have performed only thyroid hormone replacement and followed up the patient. Plasma thyroid stimulating hormone (TSH) and prolactin concentrations returned to normal range in a few months after starting thyroid hormone replacement. Furthermore, the finding of pituitary enlargement has completely disappeared on brain CT and come to pregnancy during the course. Thus, it seems that the finding of pituitary enlargement might be due to pituitary hypertrophy. Therefore, we think that thyroid hormone replacement should be a first choice therapy preceding the pituitary surgery or bromocriptine therapy in such a case.

Adult↗
PubMed1991

Effect of insulin, glucagon or dexamethasone on the production of insulin-like growth factor I in cultured rat hepatocytes.

We studied the effect of insulin, glucagon or dexamethasone on the production of insulin-like growth factor I (IGF-I) by cultured rat hepatocytes. Hepatocytes were isolated from normal adult rat livers and cultured in MEM, as nearly confluent monolayers. In the absence of such hormones, IGF-I and albumin accumulated in the culture medium almost linearly for periods up to 24 hours with the accumulation rates of 140 mU/mg cell protein per hour and 1.2 micrograms/mg cell protein per hour, respectively. Cycloheximide (5 micrograms/ml) almost completely inhibited the accumulation of IGF-I and albumin in the medium. Insulin at concentrations over 10(-10) M significantly inhibited the production of IGF-I in spite of the increased production of albumin. Conversely, glucagon stimulated the production of IGF-I at concentrations over 10(-8) M, but inhibited the production of albumin at concentrations over 10(-10) M. Dexamethasone stimulated the production of IGF-I at concentrations over 10(-7) M, but had no significant effects on the production of albumin. Thus, IGF-I production of hepatocytes is regulated by several hormones with different manner from albumin production.

Animals↗