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Biomedical subjects

Y Iwakura

Publications and source records attributed to Y Iwakura.

At least 109 records · Page 6Linked to original sources
PubMed1992

Effects of proteolytic enzyme inhibitors as absorption enhancers on the transdermal iontophoretic delivery of calcitonin in rats.

The effects of proteolytic enzyme inhibitors, aprotinin, soybean trypsin inhibitor and camostat mesilate as absorption enhancers on the transdermal iontophoretic delivery of salmon calcitonin (SCT) have been examined in rats. The dermal absorption of SCT was evaluated with hypocalcaemic effect. Application of SCT (12.5 int. units/rat) onto abdominal skin did not produce any hypocalcaemic effect. This produced a small hypocalcaemic effect with cationic iontophoresis (drug phase, anode; reference phase, cathode; high frequency pulses of 1 V at 10 kHz, 2h). Furthermore, camostat mesilate (1 mM) and aprotinin (10(6) int. units mL-1) enhanced the hypocalcaemic effects on the application of SCT with iontophoresis. These hypocalcaemic effects were highest with the pH 4.0 preparation compared with those of the pH 5.5, pH 7.0 and pH 8.0 preparations. However, soybean trypsin inhibitor did not change the hypocalcaemic effects. This was because the soybean trypsin inhibitor is a relatively high molecular weight peptide (mol. wt 8000) and an anion at used pH, and therefore was not absorbed through rat skins with cation iontophoresis.

Absorption↗
PubMed1991

Induction of inflammatory arthropathy resembling rheumatoid arthritis in mice transgenic for HTLV-I.

Human T cell leukemia virus type-I (HTLV-I) is the etiologic agent of adult T cell leukemia and has also been suggested to be involved in other diseases such as chronic arthritis or myelopathy. To elucidate pathological roles of the virus in disease, transgenic mice were produced that carry the HTLV-I genome. At 2 to 3 months of age, many of the mice developed chronic arthritis resembling rheumatoid arthritis. Synovial and periarticular inflammation with articular erosion caused by invasion of granulation tissues were marked. These observations suggest a possibility that HTLV-I is one of the etiologic agents of chronic arthritis in humans.

Animals↗
PubMed1991

Effects of proteolytic enzyme inhibitors on the nasal absorption of vasopressin and an analogue.

Proteolytic enzyme inhibitors were examined as absorption enhancers for the nasal delivery of vasopressin (AVP) and desmopressin (1-d-8-DAVP) in rats. Aprotinin, soybean trypsin inhibitor, and camostat mesilate were used as enzyme inhibitors. The nasal absorption of AVP and 1-d-8-DAVP was evaluated by measuring its antidiuretic effect. Nasal administration of AVP (0.005 IU/kg) or 1-d-8-DAVP alone (2.5 ng/kg) produced a small antidiuretic effect. Coadministration with aprotinin (1000 and 10000 KIU/kg) or soybean trypsin inhibitor (1.25 and 6.25 mM) did not change the antidiuretic effect. However, coadministration with camostat mesilate (1 to 50 mM) significantly increased the antidiuretic effect and, thus, the nasal absorption of AVP and 1-d-8-DAVP. The activities of aminopeptidase, cathepsin-B, and trypsin in the nasal mucosal tissue of rats were 7 nmol/min/mg protein, 0.7 nmol/min/mg protein, and 4.6 pmol/min/mg protein, respectively. Aprotinin and soybean trypsin inhibitor inhibited only the trypsin activity, whereas camostat mesilate inhibited aminopeptidase and trypsin activities. Aprotinin (MW 6500) and soybean trypsin inhibitor (MW 8000), with relatively high molecular weights, may not permeate into the nasal mucosal tissue. In contrast, camostat mesilate is slowly absorbed (8%/hr) and could inhibit the proteolytic activity in the nasal mucosa, resulting in enhanced nasal absorption of AVP and 1-d-8-DAVP.

Administration, Intranasal↗
PubMed1991

Effects of viscous hyaluronate-sodium solutions on the nasal absorption of vasopressin and an analogue.

The effects of viscous solutions of hyaluronate-sodium of various average molecular weights (MW) on the nasal absorption of vasopressin (AVP) and its analogue, 1-deamino-8-D-arginine vasopressin (1-d-8-DAVP), were examined in rats. Solutions of hyaluronate with MW greater than 3 x 10(5) daltons enhanced the nasal absorption of AVP; solutions of MW 5.5 x 10(4) daltons were not effective. The enhancing effects on the nasal absorption of AVP and 1-d-8-DAVP were dependent on the concentration in the range of 0-1.5% (w/v) hyaluronate (MW 1.4 x 10(6) daltons). The nasal absorption of AVP was increased with this solution at lower pH. Bioavailabilities after nasal administration of AVP and 1-d-8-DAVP in hyaluronate solutions (MW 1.4 x 10(6) and 2 x 10(6) daltons) increased more than 2-and 1.6-fold as compared to nasal administration of AVP and 1-d-8-DAVP in buffer solutions (pH 7.0), respectively. Hyaluronate solution (MW 1.4 x 10(6) daltons) did not affect the ciliary beat frequency of rabbit nasal mucosal membranes in vitro. Therefore, hyaluronate solution may be useful as a vehicle for nasal delivery of AVP and 1-d-8-DAVP.

Absorption↗
PubMed1990

Induction of interferon-alpha by interferon-beta, but not of interferon-beta by interferon-alpha, in the mouse.

The antigenicity of the interferon (IFN) produced in transgenic mice carrying an extra mouse IFN-beta gene under the control of mouse metallothionein-I enhancer-promoter was examined after induction with Cd2+. Unexpectedly, IFN-alpha in addition to IFN-beta was detected in the serum. Induction of IFN-alpha was also observed when recombinant mouse IFN-beta was injected into normal mice. IFN-alpha was first detected in the circulation 6-10 hr after the administration of IFN-beta, and after 12 hr, IFN-alpha became the major component of serum IFN. On the other hand, when IFN-alpha was injected, no production of IFN-beta was observed. Messenger RNAs specific for IFN-alpha and endogenous IFN-beta were detected in the spleen, though the amount of IFN-beta mRNA was much less than that of IFN-alpha mRNA. These mRNAs were not detected in other organs including the liver where exogenous IFN-beta gene was markedly expressed. These observations showed that the expression of IFN-alpha is inducible by IFN-beta in the mouse, and the spleen was suggested to be the main site of production. Possible mechanisms of the induction are discussed.

Animals↗
PubMed1990

A novel transcriptional regulatory factor that binds to the polyoma virus enhancer in a developmental stage-specific manner.

By using gel mobility shift assay, it was shown that the nuclear extract from F9 embryonal carcinoma (EC) cells contains a novel transcriptional regulatory factor, BF-H, that binds to the 5' upstream region of the early gene of polyoma virus. Two binding sites were located in the transcriptional enhancer domain "A" (nucleotide 5034-5041) and in the 5' upstream of the domain "A" (4998-5005), having a consensus motif (AAPuATGG) between them. Combination of in vitro mutagenesis with chloramphenicol acetyltransferase (CAT) assay revealed that BF-H is a positive transcriptional factor. Interestingly, the binding of BF-H disappeared after differentiation of F9 cells by treatment with retinoic acid, whereas BF-H was present in the F9 cells differentiated with both retinoic acid and dibutyryl cyclic AMP (dbcAMP). These observations suggest that BF-H regulates the expression of genes in a developmental stage-specific manner in early embryos of the mouse.

Adenovirus Early Proteins↗
PubMed1988

Male sterility of transgenic mice carrying exogenous mouse interferon-beta gene under the control of the metallothionein enhancer-promoter.

As an approach to elucidating the roles of interferon (IFN) in the normal physiology and diseases of animals, transgenic mice carrying extra mouse IFN-beta genes under the control of a mouse metallothionein I enhancer-promoter were constructed. Upon induction with Cd2+, IFN activity (15-430 IU/ml) was detected in the sera of six out of ten transgenic mouse lines so far obtained. Synthesis of mRNA of the transgene was observed in the liver, the testis and less abundantly in the brain. Interestingly, IFN mRNA was constitutively synthesized in the testis where substantial levels of IFN accumulated without heavy metal induction, whereas synthesis in the liver was mostly dependent on induction by CD2+. Since IFN activity in the serum also depended on heavy metal induction, the IFN in the serum may be produced mainly in the liver. All males expressing the IFN gene in the testis were found to be sterile. Testes were involuted and contained few mature sperm, and degeneration of spermatocytes and spermatids was observed. These findings suggest that high levels of IFN are harmful to spermatogenesis and can cause male sterility.

Animals↗
PubMed1988

Synthesis and distribution of carbohydrate chains in cleavage-stage mouse embryos carrying the t12 lethal mutation.

Carbohydrate chains on the t12 mutant embryos were analyzed. No abnormalities of the synthesis of the carbohydrate chains were observed in the t12 homozygotes until the late morula stage, when radiolabeled carbohydrate chains were analyzed by Sephadex G-50 column chromatography. Furthermore, polarization of the Con A receptor occurred normally at the eight-cell stage. Therefore, the possible defects of the carbohydrate chains on the t12 embryos were suggested to be neither gross abnormality of the synthesis nor abnormal localization on the surface, but rather minor structural changes on a specific molecule.

Alleles↗
PubMed1988

Interferon production under the control of heterologous inducible enhancers and promoters.

In a search for a useful enhancer to control expression of interferon (IFN) gene in mammalian cells, mouse IFN-beta cDNA ligated 3' downstream to the enhancer-promoter of either mouse metallothionein-I (MT-I) or Drosophila heat shock protein (HSP) was introduced into various cultured cells by calcium-phosphate precipitation method, and the level of IFN transiently produced was compared. In the case of the MT-I enhancer-promoter, low levels of IFN were produced without induction (0-21 IU/ml) and the level increased 5-50 times by heavy metals. In contrast, the basal level of expression of the HSP enhancer-promoter was very low and its expression was increased several hundred to thousand times by heat shock or arsenite. Thus the HSP enhancer-promoter appears to be a potent inducible element with very low basal level and high inducibility.

Animals↗
PubMed1988

Clonal isolation and characterization of myoblast-like reconstituted cells formed by fusion of karyoplasts from mouse teratocarcinoma cells with rat myoblast cytoplasts.

To examine the roles of the cytoplasms of differentiated somatic cells on nuclear gene expression, reconstituted cells (RC-cells) were isolated clonally by fusing karyoplasts (isolated nuclei) from neomycin-resistant mouse teratocarcinoma PCC4-neor cells with cytoplasts (isolated cytoplasms) of chloramphenicol (CAP)-resistant rat myoblasts L6TG.CAPr cells, and after double selection in the medium containing 400 micrograms/ml of neomycin and 100 micrograms/ml of CAP (G418 plus CAP medium). The RC-cells were characterized by the presence of two genetic markers, neomycin- and CAP-resistance, by the absence of latex beads which had incorporated into karyoplast donor PCC4-neor cells as a cytoplasmic physical marker, and by the similar karyotypes as that of parental PCC4-neor cells. In contrast to the teratocarcinoma cybrids previously isolated, all the isolated RC-clones expressed myoblast-like morphologies of three types. The phenotypic expression of these RC-cells was compared with that of PCD-1 cells, a teratocarcinoma-derived myoblast line. RC-cells and PCD-1 cells did not express alkaline phosphatase (ALPase) activity while parental PCC4-neor expressed it strongly. After induction of myogenic differentiation by treatments with excess thymidine and conditioned medium, two clones were capable of forming short multinucleated cells. The protein synthetic patterns of RC-cells analysed by two-dimensional polyacrylamide gel were different from PCC4-neor cells, and quite resembled those of PCD-1 cells. Particularly, multinucleated RC-clones expressed alpha-tropomyosin, and contained 10 nm filaments, characteristic markers of early myogenic cells. These results suggest that the RC-cells are myoblast-like cells, that a few of them maturate to partially differentiated myogenic cells, that the rat myoblast cytoplasm contains regulatory factor(s) able to determine the myogenic cell lineage of the undifferentiated stem cells, and that this factor is continuously expressed in these myoblasts.

Alkaline Phosphatase↗
PubMed1987

Effects of tunicamycin on the differentiation of F9 cells induced by either retinoic acid or retinoic acid and dibutyryl cyclic AMP.

Tunicamycin (0.5 micrograms/ml) inhibited differentiation of F9 cells treated either with retinoic acid or with retinoic acid and dibutyryl cyclic AMP, as monitored by the activity of alkaline phosphatase and expression of cytokeratins. On the other hand, the pattern of the polysaccharide chain synthesis changed drastically with the treatment irrespective of the presence of tunicamycin. Therefore, phenotypes induced with retinoic acid are dissociated into two categories, one that is directly induced by the drug and the other that is induced indirectly by a mechanism in which glycoproteins play a role.

Animals↗
PubMed1986

Studies of developmental abnormalities at the molecular level of mouse embryos homozygous for the t12 lethal mutation.

Embryos obtained by crossing heterozygous t12 mutant mice were labeled metabolically with 14C-amino acids at the mid-morula stage, and the protein pattern of single embryos was examined by two-dimensional polyacrylamide gel electrophoresis. After labeling, the morphology was still normal. The genotypes of the embryos could be identified by the allelic forms of Tcp-1 (p63/6.9) protein on the gel. In t12/t12 embryos, the bulk of syntheses of macromolecules such as proteins and RNAs [poly(A)+, as well as poly(A)-RNA] was normal, however, syntheses of several proteins were markedly reduced. Some of these proteins present in reduced amounts appeared to be components of cytokeratin-type intermediate filaments (endo A and endo B), judging from their insolubility in non-ionic detergent, their appearance in the mid-morula stage, their location in trophectodermal cells, and their electrophoretic mobilities. These observations suggest that mechanisms for the induction of the intermediate filament proteins are defective in embryos homozygous for the t12 mutation. Possible relationships between the morphological abnormalities of the embryos and their defective synthesis of intermediate filaments are discussed.

Alleles↗
PubMed1985

SV40 vector with early gene replacement efficient in transducing exogenous DNA into mammalian cells.

An early replacement SV40 vector, SV40-Mu beta, was constructed by replacing part of the early genes of the virus with mouse interferon-beta (IFN-beta) cDNA. Upon transfection of COS-7 cells with this DNA, transducing viral particles were produced, which could infect various cells and cause efficient production of mouse IFN-beta. The viral stock contained no detectable wild-type SV40. The IFN production after the virus infection was very high in monkey kidney cells, but less so in human epithelial cells, and low in mouse, pig, hamster cells and in human lymphocytes. The efficiency of introduction of the DNA to monkey kidney cells was compared with that by the calcium phosphate precipitation method, and the viral vector was found to be more efficient by a factor of several tens to hundreds.

Animals↗
PubMed1985

Effects of tunicamycin on preimplantation mouse embryos: prevention of molecular differentiation during blastocyst formation.

To examine the role of carbohydrate-containing molecules of preimplantation mouse embryos in early development, effects of tunicamycin were analyzed at the molecular level. Embryos cultured in the presence of tunicamycin (0.1 micrograms/ml) from earlier than the 16-cell stage did not develop into blastocysts, though cell divisions continued normally. Tunicamycin inhibited not only the synthesis of carbohydrate chains of usual N-glycosidic glycoproteins but also that of characteristic large polysaccharides (Mr greater than 9K) of early embryos. Expression of several polypeptides which are characteristic of the blastocyst stage (blastocyst-characteristic proteins: BCPs) was strongly inhibited in the embryos treated by tunicamycin from earlier than the 16-cell stage, while the expression was not inhibited in the embryos treated by the drug after that stage as analyzed by two-dimensional polyacrylamide gel electrophoresis. The expression of BCPs appeared to be dependent on de novo mRNA synthesis, since it was also inhibited by alpha-amanitin treatment. Since tunicamycin was shown not to inhibit expression of most other proteins and the bulk of mRNA, the inhibitory effects of tunicamycin appeared to be specific for the induction of BCPs. These observations suggest that the glycoprotein(s) and/or the characteristic large polysaccharides on the morula stage embryos play an essential role not only for morphological development but also for triggering differentiation at the molecular level.

Amanitins↗
PubMed1985

Pleiotropic phenotypic expression in cybrids derived from mouse teratocarcinoma cells fused with rat myoblast cytoplasts.

Cybrid clones were isolated by fusing mouse embryonal carcinoma (PCC4) cells with cytoplasts of rat myoblastic cells (L6TG X CAPr). Although some clones were similar to PCC4 (Type II), a high proportion (88%) were differentiated; the differentiated cells had a mesh-like arrangement (Type I) or were flat with many projections (Type III). Protein patterns of both Type I and Type III cells changed markedly from that of PCC4 cells. Type III cells lacked alkaline phosphatase and expressed endo A and B proteins predominantly. One Type III clone produced alpha-fetoprotein and plasminogen activator (visceral endoderm-like), while another clone consisted of trophectodermal cell-like giant cells. Therefore it was shown that introduction of the somatic cell cytoplasm induces differentiation of teratocarcinoma stem cells, suggesting a cytoplasmic element (or elements) regulating gene expression.

Alkaline Phosphatase↗