Search PubMed⌕ Search

Biomedical subjects

M Iwai

Publications and source records attributed to M Iwai.

At least 127 records · Page 7Linked to original sources
PubMed1994

Mouse Mammary Tumor Virus Proviral Integration in the DD/Tbr Mice.

The patterns of mouse mammary tumor virus (MMTV) integration in the DNA of spontaneous-mammary tumors, salivary glands and livers of DD/Tbr mice were examined using MMTV env, int -1c and int-2c probes. The MMTV env probe revealed 1 to 7 new proviral insertions in all mammary tumors. MMTV integration into int-1 was observed in 10 of 18 mammary tumors, whereas that into int-2 was seen in only 2 of 18 tumors. Of the 13 salivary glands examined, only 3 showed new MMTV proviral integrations, but rearrangement in int-1 or int-2 loci by MMTV was not observed. Immuno-collidal gold electron microscopy revealed the presence of MMTV particles both in mammary tumors and in salivary glands, but no tumors were found to be developed in salivary glands. Taken together these results suggest that salivary glands support MMTV replication, but the virions thus produced may not lead to salivary gland tumorigenesis. It is suggested that the salivary gland is the source of horizontally transmitted MMTV in DD/Tbr mice.

Journal Article↗
PubMed1994

Reduced hepatic release of apoprotein B after enteral nutrition in rats.

To investigate the effects of enteral and parenteral alimentation on VLDL release from the liver, a lipid-free liquid nutriment was continuously administered to free-moving rats via the oral cavity (oral group), stomach (enteral group) or superior caval vein (parenteral group). After 1-week of nutrition, the plasma VLDL concentrations were significantly lowered in the enterally-fed group. By immunoblotting assay using a specific antiserum, plasma contents of both apoprotein B-100 and B-48, the major components of rat apoprotein B, were found to be decreased in the enteral group, whereas only that of apoprotein B-48 was reduced in the parenteral group as compared with the oral group. Sucrose gradient centrifugation of the lipid droplets in the liver from the enteral group showed an increase of the free-triacylglycerol fraction with a concomitant increase of the apoprotein B-48-rich triacylglycerol fraction. These results suggest that enteral nutrition causes triacylglycerol accumulation in the liver, at least in part by impairment of lipoprotein release from the liver.

Animals↗
PubMed1994

Tumour necrosis factor alpha inhibits in-vitro decidualization of human endometrial stromal cells.

Interleukin-1 (IL-1) has been reported previously to inhibit the in-vitro decidualization of human endometrial stromal cells as assessed by progesterone-induced prolactin production and morphological transformation. In this study we examined whether other cytokines, such as tumour necrosis factor-alpha (TNF alpha), interferon-beta (IFN beta), IFN gamma or granulocyte-macrophage colony-stimulating factor (GM-CSF), could affect the decidualization of human endometrial stromal cells in vitro. Of these cytokines, TNF alpha significantly suppressed prolactin production in a dose-dependent manner, with no apparent effect on cell number. The morphological transformation of endometrial stromal cells was also inhibited by TNF alpha. TNF alpha and IL-1 significantly suppressed cAMP-stimulated prolactin production by endometrial stromal cells. Neither the progesterone concentration in the supernatant of the endometrial stromal cell culture system nor intracellular calcium concentration of the endometrial stromal cells were affected by the addition of TNF alpha or IL-1. These results indicated that TNF alpha and IL-1 suppress both progesterone-induced and cAMP-mediated prolactin production in endometrial stromal cells, and that this inhibition was not attributable to direct effects on progesterone metabolism or related to Ca(2+)-mediated signal transduction. These experiments suggested that a local increase of TNF alpha and IL-1 under certain pathological conditions in vivo may disturb blastocyst implantation and/or the maintenance of pregnancy by inhibiting the decidualization of endometrial stromal cells.

Cells, Cultured↗
PubMed1994

Expression of leukemia inhibitory factor in human endometrium and placenta.

Leukemia inhibitory factor (LIF), a cytokine that induces macrophage differentiation in the murine M1 myeloid leukemia cell line, is essential for blastocyst implantation in mice. However, its expression and the role it plays in the human uterus are unknown. To clarify these issues, we examined LIF gene expression in the human uterus by Northern blot hybridization and by a quantitative reverse transcription-polymerase chain reaction (RT-PCR) method. Analysis of LIF mRNA showed two hybridization bands, with estimated mRNA sizes of about 4.0-kb pairs and 1.8-kb pairs. LIF mRNA was detected at high levels in endometrial tissue and decidua, but at low levels in the chorionic villus in first trimester and term placenta. In the secretory phase, the endometrial tissue showed higher LIF expression than in the proliferative phase (9.5-fold; p < 0.01). The endometrial tissues were separated into a stroma-enriched fraction (SF) and an epithelium-enriched fraction (EF), and the LIF mRNA levels in each fraction were examined by quantitative RT-PCR. These levels were higher in the EF than in the SF (3.3-fold; p < 0.05). These findings suggest that, in humans, LIF plays a role in uterine function during the menstrual cycle, as well as during pregnancy.

Base Sequence↗
PubMed1994

High incidence of uterine inversion in mast cell-deficient osteopetrotic mutant mice of mi/mi genotype.

Mutations at either W or mi (microphthalmia) loci in the mouse can lead to a deficiency in melanocytes and mast cells. In addition, W mutants can be anemic and sterile, whereas mi mice are osteopetrotic because of a monocyte/macrophage/osteoclast defect. Since c-kit receptor tyrosine kinase is the gene product of the W locus and mi mutation has been suggested to affect the transduction of signals from the c-kit and c-fms receptors, we here examined the effect of mi mutation on fertility. Testes and ovaries from mi/mi mice were histologically normal, and the pattern of c-kit protein expression was not different from that of +/+ mice. Homozygous mutant crosses (mi/mi x mi/mi) were fertile, but inversion of the uterus occurred in 86% of the deliveries. In some cases, the placenta was found still attached to the inverted uterus after delivery. Decidual cells were present and expressed c-kit protein normally in the placenta of mi/mi mice. The inversion was also observed in mi/mi females mated to +/+ males. No uterine inversion was noted when +/mi females were crossed with mi/mi or +/mi males, suggesting that the genotype of the mother but not of the father or fetus is important for the pathogenesis. The numbers and body weights of mi/mi newborns were less than those of +/mi littermates. Mast cells were absent, but c-kit-positive cells were present, in the uterine muscle layers of pregnant mi/mi mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Induction of the conversion of xanthine dehydrogenase to oxidase in rabbit liver by Cu2+,Zn2+ and selenium ions.

Effects of Cu2+,Zn2+,Fe2+ and selenium ions on the conversion of xanthine dehydrogenase to oxidase in rabbit liver were examined. Under basal conditions, xanthine oxidase activity represented only 16% of the total xanthine oxidase plus dehydrogenase activity. Cu2+ (2-10 microM), Zn2+ (5-30 microM) and selenium ions (5-100 microM) brought about the conversion of xanthine dehydrogenase to oxidase in a dose-dependent manner. The concentrations of Cu2+,Zn2+ and selenium ions required for increasing xanthine oxidase activity by 50% was approximately 4, 10 and 20 microM, respectively. On the other hand, Fe2+ had no effect on the conversion of the enzyme up to 100 microM. These results suggest that Cu2+,Zn2+ and selenium ions have the potential to modulate the conversion of xanthine dehydrogenase to oxidase in rabbit liver.

Allopurinol↗
PubMed1994

Distribution of mouse mammary tumor virus in Asian wild mice.

Several groups of wild mice (Mus musculus) were captured from eight different locations in Asia and bred for several generations in a facility free of any laboratory strains of mice carrying mouse mammary tumor virus (MMTV). The distribution of endogenous MMTV proviral sequences in the liver tissues of these mice was investigated by using Southern blot hybridizations. Four categories of mice were identified. Mice originating from Bogor, Indonesia (Cas-Bgr); He-mei, Taiwan (Cas-Hmi/1); and Malaysia (Cas-Mal) were found to carry an endogenous MMTV provirus consisting of the env, gag-pol, and long terminal repeat sequences. Mice captured from Kojuri, Republic of Korea (Sub-Kjr); Nagoya, Japan (Mol-nag); and three Chinese provinces, Shanghai (Sub-Shh), Beijing (Sub-Bjn), and Jiayuguang (Sub-Jyg/1), appeared to carry defective proviruses. Some mice originating from He-mei (Cas-Hmi/2) and Jiayuguang (Sub-Jyg/2) were found to be completely free of endogenous MMTV. Interestingly, however, the Sub-Jyg/2 mice, after several generations of inbreeding, were found, unlike all of the other subspecies that we examined in the present study, to develop mammary tumors at a high incidence (80 to 90%) with a short period of latency. Electron microscopic examination of the mammary glands and mammary tumors of these mice revealed the presence of numerous intracytoplasmic A, immature, budding, and mature B particles. Furthermore, the mammary tumors were found to contain MMTV proviral sequences. It seems, therefore, that Sub-Jyg/2 mice carry an exogenous MMTV which contributes to their developing mammary tumors.

Animals↗
PubMed1994

Progesterone enhances macrophage colony-stimulating factor production in human endometrial stromal cells in vitro.

Increasing evidence suggests that macrophage colony-stimulating factor (M-CSF) is produced in the uterine endometrium and that it plays an important role in the reproductive process. In the present study, using an in vitro decidualization model and human endometrium, we investigated M-CSF messenger RNA (mRNA) expression in human endometrial stromal cells (ESC) by Northern blotting and in situ hybridization. The secreted M-CSF in the culture medium of ESC was measured by enzyme-linked immunosorbent assay. ESC were cultured in the presence of progesterone (P) or estrogen. After a 9-day culture with P, when in vitro decidualization was confirmed by the production of PRL, M-CSF mRNA and protein levels were 3.1 +/- 0.5- and 3.2 +/- 0.8-fold (mean +/- SEM) higher, respectively, than those in cultures without P (P < 0.01). The P-induced increase was dose dependent. On the other hand, estrogen did not increase M-CSF mRNA expression. M-CSF mRNA expression in the first trimester deciduae that expressed PRL mRNA was higher than that in the endometria. By in situ hybridization, ESC as well as epithelial cells were shown to express M-CSF both in vitro and in vivo. These findings indicate that human ESC (decidua cells) express M-CSF mRNA and suggest that they secrete M-CSF in a P-dependent manner during the process of decidualization.

Adult↗
PubMed1994

Immunocytochemical investigation of rat gamma-glutamyl transpeptidase in chemically-induced hepatocarcinogenesis using monoclonal antibody.

An immunocytochemical study using a monoclonal antibody showed the presence of gamma-glutamyl transpeptidase (gamma-GTP) in the bile duct epithelium of the normal adult rat liver, while a slight immunoreactivity for gamma-GTP could be observed on the membranes of bile canaliculi (the membranes of hepatocytes facing the lumen of bile canaliculi). In hepatocarcinogenesis induced by 3'-methyl-4-dimethylaminoazobenzene, no immunoreactivity was detected in alpha-fetoprotein-positive cholangiolar "oval" cells, though it was detected on the membranes of bile canaliculi. In livers with hyperplastic nodules, gamma-GTP immunoreactivity was observed in clusters, with two different staining patterns. In one pattern, gamma-GTP was present not only on the membranes of bile canaliculi, but also on the membranes facing the Disse's space or the lateral cell surface of hepatocytes. In the other pattern, gamma-GTP immunoreactivity was seen on the membranes of the dilated bile canaliculi. In livers with developing hepatocellular carcinomas, the immunoreactivity was present on the membranes of irregularly dilated bile canaliculi in malignant cells.

Animals↗
PubMed1994

Combination of ascorbic acid and methylprednisolone pulse therapy in the treatment of idiopathic thrombocytopenic purpura.

Ascorbic acid, reported in 1988 to be effective for idiopathic thrombocytopenic purpura (ITP), is an attractive drug because of its lack of toxicity. Further studies are necessary in order to improve its effectiveness without increasing secondary effects. We present a chronic ITP patient treated with a combination of ascorbic acid and methylprednisolone pulse (MP) therapy who was previously treated with MP therapy alone. The effect of this combination therapy seems to be better than MP therapy alone. This therapy is worth further examination as another therapeutic choice due to its fewer secondary effects than the usual regimen of corticosteroids, splenectomy, and other immunosuppressive drugs.

Aged↗
PubMed1994

Pigmentary retinopathy with nephrotic syndrome, Ménétrier's disease, and diabetes mellitus.

A patient with pigmentary retinopathy, nephrotic syndrome, Ménétrier's disease, and diabetes mellitus is presented. Other complications were congestive heart failure, hypothyroidism, hypertension, and hypertriglyceridemia. Hypogenitalism was also suspected. Pigmentary retinopathy is known to associate with many systemic diseases, which are classified into several syndromes. This case superficially resembles Alström's disease due to the common characteristics of pigmentary retinopathy, diabetes mellitus, renal disease, and hypogenitalism. But clinically and histologically, there are distinct differences. To our knowledge, this association has never been reported.

Consanguinity↗
PubMed1993

Non-radioisotopic quantitative RT-PCR to detect changes in mRNA levels during early mouse embryo development.

We developed a non-radioisotopic quantitative RT-PCR method with high sensitivity and reproducibility. The results of this RT-PCR were in agreement with those of the Northern blot analysis. We measured the mRNA levels of beta-actin, transferrin receptor, and two cell cycle-related genes, cyclin B and cdc25, in early mouse embryos by the RT-PCR. In late two-cell stage embryos, beta-actin, transferrin receptor and cyclin B mRNA levels were 10-20% of those in MII stage oocytes. In contrast, the cdc25 mRNA levels were not different between these stages. When we cultured mouse embryos, the presence of an RNA polymerase inhibitor, alpha-amanitin, in the medium did not affect the mRNA levels at the two-cell stage, indicating that most of the detected mRNAs in two-cell embryos were maternally derived. These results suggest that the rate of mRNA degradation is different between cyclin B and cdc25 during early embryogenesis.

Actins↗
PubMed1993

Direct evidence for preferential multiplication of Babesia gibsoni in young erythrocytes.

To clarify the effect of the age of host erythrocytes on the multiplication of Babesia parasites, B. gibsoni was cultured together with reticulocytes, immature erythrocytes, or mature erythrocytes from dogs. Parasitemia reached peak levels (34.1% +/- 15.8%) at cultivation day 8 in immature-erythrocyte culture, whereas the highest parasitemia attained in mature-cell culture was only 3.6% +/- 2.2% at day 5. These results clearly demonstrate that B. gibsoni parasites preferentially invade and multiply in young erythrocytes rather than in mature cells.

Animals↗
PubMed1993

Effects of bile acids and taurine on the lipid fluidity of hepatic microsomes in normal and bile duct-ligated rats--a spin label study.

In cholestasis and obstructive jaundice, hepatic bile acids and taurine content increase significantly and bile acids change in compositions. For example, increases in cholic acid, beta-muricholic acid and taurine-conjugated bile acids occur in rats. In this study, to clarify the significance of changes in bile acid composition in obstructive jaundice, the effects of various bile acids and taurine on the fluidity of the hepatic microsomal membrane were studied by the electron spin resonance spin-label method in normal and bile duct-ligated (for 10 days) rats. The flow properties (order parameter) of the shallow and deep layers of the membrane were determined with 5- and 12-doxyl stearic acid, respectively. Bile acids mainly affected the fluidity of the shallow membrane layer. The fluidity of the hepatic microsomal membrane was decreased in bile duct-ligated rats. Conjugated cholic acid (taurine-conjugated cholic acid, glycine-conjugated cholic acid and non-conjugated beta-muricholic acid exerted effects that increased fluidity in comparison with non-conjugated cholic acid and chenodeoxycholic acid, a precursor of beta-muricholic acid. Taurine had no clear effect on fluidity. In conclusion, cholic acid conjugation and beta-muricholic acid formation may be mechanisms which protect against the decrease in lipid fluidity of hepatic biomembranes in cholestasis or obstructive jaundice. Taurine may also affect fluidity through the formation of taurine-conjugated bile acids.

Animals↗
PubMed1993

The expression of c-kit protein in human adult and fetal tissues.

The c-kit proto-oncogene encodes a tyrosine kinase receptor and is allelic with the dominant white-spotting (W) locus of the mouse. In this study we investigated the expression of human c-kit protein in various adult and fetal human tissues immunohistochemically using anti-human c-kit monoclonal antibody. To discriminate c-kit+ cells from mast cells expressing c-kit, mast cells were identified by staining with Toluidine blue. In oogonia, spermatogonia and skin melanocytes of the fetus and in oocytes of adult ovary, c-kit expression was detected. In adult uterus, c-kit+ cells were widely distributed in the basal layer of the endometrium, myometrium and cervix, the number and distribution being almost identical to those of mast cells. In fetal uterus, c-kit+ non-mast cells clustered beneath the epithelium and a few mast cells were observed in the myometrium and subserosal layer. In both adult and fetus, c-kit+ non-mast cells were detected within smooth muscle layers of the intestine, colon and oesophagus, while mast cells were observed in the mucosal and submucosal layers of these organs. In contrast to mice, no expression of c-kit protein was detected in the human placenta and decidua. Thus, the distribution of c-kit+ cells in various tissues is similar but not identical between adult and fetus and between human and mouse.

Adult↗
PubMed1993

Localization of endothelin receptor messenger ribonucleic acid in the rat ovary and fallopian tube by in situ hybridization.

Rat mRNAs encoding two subtypes of the endothelin (ET) receptor (ET(A) and ETB) were studied in the rat ovary and fallopian tube by means of Northern blotting and in situ hybridization. The mRNA transcripts for the endothelin-1-specific type receptor (ET(A)) in pooled RNA from the ovary and fallopian tube were 4.2 and 5.2 kilonucleotides, and that for the nonselective type receptor (ETB) was 4.7 kilonucleotides; these were similar to transcripts for endothelin receptors from other tissues. ET(A) mRNA expression was abundant in the muscle cell layer of the fallopian tube, but low in the ovary. On the other hand, ETB mRNA was abundant in the granulosa cells in the developing follicles, but low in atretic follicles and absent in the fallopian tube. These results demonstrated that the mRNAs for the two subtypes of the rat endothelin receptor have different expression profiles in the ovary and fallopian tube. ETs may mainly affect the granulosa cells in the dominant follicles as well as the muscle cells of the fallopian tube through ETB and ET(A), respectively.

Animals↗
PubMed1993

Mammary tumour induction by pituitary grafting in male mice: an animal model for male breast cancer.

Isologous anterior pituitary grafting, 4 each, to 3-4-month-old SHN and SLN male mice resulted in an appearance of mammary tumours from 8 months of age and the incidence at 12 months reached 53.8% in each strain. All tumours were diagnosed as type B adenocarcinomas. In association with the results, normal mammary gland growth and mouse mammary tumour virus (MMTV)-gp52 antigen levels in the submaxillary glands were stimulated by the treatment in these strains. The effect of pituitary grafting was much less in GR/A male mice in which no mammary tumours appeared.

Adenocarcinoma↗