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Biomedical subjects

Y Nagai

Publications and source records attributed to Y Nagai.

At least 19 recordsLinked to original sources
PubMed1992

Human peripheral blood lymphocytes express D5 dopamine receptor gene and transcribe the two pseudogenes.

Sequential reverse transcription and polymerase chain reaction (RT-PCR) of the mRNA were used to investigate the expression of dopamine receptors in human peripheral blood lymphocytes. The RT-PCR products contained three types of sequences, each corresponding to those of the D5 dopamine receptor gene and the two related pseudogenes. The lymphocyte cDNA library also contained the clones encoding parts of the three genes. Binding profiles of dopaminergic ligands to the lymphocytes were similar to those for the native neuronal membranes.

Benzazepines↗
PubMed1992

[Studies on thyroid hormone autoantibody in two euthyroid cases with spuriously high value of serum free triiodothyronine].

Spuriously high value of serum free triiodothyronine (FT3: Amerlex free T3 kit, Amersham, UK.) was noted accidentally on routine laboratory examination of two clinically euthyroid patients (case 1: FT3; 18.5 pg/ml, FT4; 1.1 ng/dl, T3; 103 ng/dl, T4; 8.2 micrograms/dl, TSH; 1.74 microU/ml, case 2: FT3; 8.5 pg/ml, FT4; 1.1 ng/dl, T3; 137 ng/dl, T4; 8.9 micrograms/dl, TSH; 1.45 microU/ml), the former with poorly controlled diabetes (FBG 253 mg/dl, HbA1c 12.1%) and the latter with essential hypertension (184/108 mmHg). Although the hypertensive patient showed mild diffuse goiter, there was no evidence that the patients had autoimmune thyroid diseases because anti-thyroglobulin antibody tests measured by radioimmunoassay and MCHA, TGHA or TBII were all negative. Their serum levels of TBG were within the normal range. Further studies revealed that both patients' sera had unusual binding activity to labelled polyaminocarboxy T3 (125I-aT3) but not labelled T3 (125I-T3). Furthermore, this binding protein was precipitated by goat anti-human immunoglobulin G (IgG). The IgG purified from both patients' sera also showed strong binding activity to 125I-aT3, which was inhibited by unlabelled T3 in a dose dependent manner. In conclusion, we found anti-T3 antibody in two clinically euthyroid patients with no apparent evidence of complicating autoimmune thyroid diseases. The stronger binding activity to polyaminocarboxy T3 rather than T3 may lead to the spuriously high value of serum FT3. The mechanisms of the production of such autoantibodies in our cases should be further investigated.

Adult↗
PubMed1992

Hepatitis C virus infection in hepatocellular carcinoma. Detection of plus-strand and minus-strand viral RNA.

BACKGROUND: Although serum antibody to hepatitis C virus (anti-HCV) is found in many patients with hepatocellular carcinoma, the actual roles of HCV in carcinogenesis are unknown. METHODS: With reverse transcription followed by the polymerase chain reaction (RT-PCR), HCV RNA was examined in the sera and liver tissues of 16 patients with hepatocellular carcinoma who did not have hepatitis B virus markers, 13 of whom had anti-HCV. RESULTS: In the 13 patients with anti-HCV, the HCV genomic plus-strand RNA was detected more frequently in noncancerous tissues (8 patients, 61.5%) and in sera (6 patients, 46.2%) than in cancerous tissues (3 patients, 23.1%). No viral RNA was found in either sera or tissues in the three patients without anti-HCV. By using a sense primer for the RT in the RT-PCR assay, amplification was attempted of a putative complementary minus-strand RNA that is believed to reflect viral replication in the eight patients with the plus-strand RNA. The minus-strand RNA was found in the noncancerous tissues of six patients; it was not detected in the cancerous tissues. CONCLUSIONS: These results suggest that HCV can infect and replicate predominantly in noncancerous cells but rarely in tumor cells.

Aged↗
PubMed1992

Parathyroid hormone inhibits 25-hydroxyvitamin D3-24-hydroxylase mRNA expression stimulated by 1 alpha,25-dihydroxyvitamin D3 in rat kidney but not in intestine.

Using a cDNA probe for rat renal 24-hydroxylase, expression of its mRNA was compared in the rat kidney and intestine. Vitamin D-deficient rats received a single injection of 1 alpha,25-dihydroxyvitamin D3. Expression of 24-hydroxylase mRNA was first detected in the kidney at 3-h post-injection and increased thereafter. Similarly, 24-hydroxylase mRNA was expressed in the intestine after 1 alpha,25-dihydroxyvitamin D3 injection. However, the dose level of 1 alpha,25-dihydroxyvitamin D3 required to induce the intestinal 24-hydroxylase mRNA expression was only 1/100 the amount required to induce renal 24-hydroxylase mRNA. Induction of intestinal 24-hydroxylase mRNA expression by 1 alpha,25-dihydroxyvitamin D3 was far more rapid than that of renal 24-hydroxylase mRNA. Thyroparathyroidectomy shortened the time required to induce expression of renal, but not intestinal, 24-hydroxylase mRNA. Administration of either parathyroid hormone or cAMP to vitamin D-deficient rats greatly reduced the expression of 24-hydroxylase mRNA in the kidney but not in the intestine. When rats were fed a vitamin D-repleted diet containing 0.7% (adequate) or 0.03% (low) calcium for 2 weeks, intestinal expression of 24-hydroxylase mRNA could be induced only in the low calcium group. In contrast, renal mRNA expression was preferentially stimulated in the adequate calcium group. These results clearly demonstrate that the expression of 24-hydroxylase mRNA is down-regulated by parathyroid hormone in the kidney but not in the intestine.

Animals↗
PubMed1992

Menstrual cycle-associated expression of 2-hydroxy fatty acyl phytosphingosine-containing GlcCer, LacCer and Gb3Cer in human uterine endometrium.

In the previous study, we found that sulfatide was characteristically expressed in the secretory phase of human uterine endometrium and that the metabolism of glycosphingolipids was strictly controlled by sex steroid hormones. Therefore, the neutral glycosphingolipid composition of human uterine endometrium in the proliferative and secretory phases was analyzed and was found to be characteristic in both phases. The major neutral glycolipids were GlcCer, LacCer, Gb3Cer and Gb4Cer. The concentrations of GlcCer, LacCer and Gb3Cer in the secretory phase were higher than those in the proliferative phase. Furthermore, on TLC, GlcCer, LacCer and Gb3Cer in the proliferative phase gave three bands, the 3rd band, which migrated to the lowest position, being much more predominant in the secretory phase. The individual band materials in both phases were purified by silica gel column chromatography, and their structures were analyzed by FABMS and GLC. The lower-migrating bands of GlcCer, LacCer and Gb3Cer were found to contain molecules with 2-hydroxy fatty acyl phytosphingosine, indicating that hydroxylation of the fatty acid and sphingosine moieties to give 2-hydroxy fatty acid- and phytosphingosine-containing glycosphingolipids, respectively, is induced selectively in the secretory phase on a change in the hormonal environment.

Cerebrosides↗
PubMed1992

Human uterine endometrial adenocarcinoma: characteristic acquirement of synthetic potentials for II3SO3-LacCer and ganglio series sulfoglycosphingolipids after transfer of the cancer cells to culture.

The acidic glycosphingolipid composition of human uterine endometrial adenocarcinoma was compared with those of normal uterine endometrium at the proliferative and the secretory phases. Upon chemical composition analysis, no significant transformation-associated change of these glycolipids was observed. However, when cancer cells from the patients with human uterine endometrial adenocarcinoma were transferred to culture, the composition of glycosphingolipids, particularly sulfoglycosphingolipids, was significantly altered after the 70th doubling time. I3SO3-GalCer, which was contained in the original tissues of uterine endometrial adenocarcinomas, disappeared completely from the cultured cells at the 70th doubling time, whereas II3SO3-LacCer and ganglio series sulfoglycosphingolipids, which were originally contained in a trace amount or not present at all in the cancer tissues, became the major components in the total acidic glycosphingolipids in the cultured cells. Also, among cell lines established from several gynecological cancers, which include uterine cervical squamous carcinoma, uterine endometrial adenocarcinoma, ovarian clear cell carcinoma, choriocarcinoma, uterine sarcoma, ovarian sarcoma, and vulvar melanoma, only those cells derived from uterine endometrial adenocarcinoma expressed II3SO3-LacCer and ganglio series sulfoglycosphingolipids and the synthetic activities of these sulfoglycolipids, indicating that uterine endometrial adenocarcinoma cells characteristically lose the sulfotransferase to GalCer and acquire the sulfotransferase to LacCer after being transferred to culture in vitro. Thus, the unique sulfoglycosphingolipids and sulfotransferase are useful markers for the characterization of uterine endometrial adenocarcinoma among human gynecological cancers.

Adenocarcinoma↗
PubMed1992

Isolation of factor Xa from chick embryo as the amniotic endoprotease responsible for paramyxovirus activation.

In chick embryo, certain paramyxoviruses mainly target the chorioallantois and the allantoamnion and show no extensive further spreading in the other organs. This has been explained by the possible presence of an endoprotease activating the viral fusion glycoprotein precursor in the allantoic and the amniotic fluid, and its absence in other places or organs. We previously isolated such an endoprotease from the allantoic fluid and demonstrated its identity with the clotting factor Xa. Exactly the same endoprotease by all the criteria including the N-terminal amino acid sequence was now isolated from the amniotic fluid. Thus, the factor Xa seems to be a major host determinant of the viral tropism in chick embryo.

Amino Acid Sequence↗
PubMed1992

Glycosphingolipids of various human ovarian tumors: a significantly high expression of I3SO3GalCer and Lewis antigen in mucinous cystadenocarcinoma.

Among several human ovarian tumors, which include mucinous cystadenocarcinoma, serous cystadenocarcinoma, and clear cell adenocarcinoma, the mucinous cystadenocarcinoma showed a unique glycosphingolipid composition. In particular, more than 90% of the acidic glycosphingolipids in the mucinous cystadenocarcinoma is comprised of sulfolipids, which are hardly detected in normal ovary and are contained in concentrations of less than 40% in the other type of ovarian tumors. By means of negative ion fast atom bombardment mass spectrometry and gas liquid chromatography, the major sulfolipid in mucinous cystadenocarcinoma is confirmed to be I3SO3-GalCer with N-cerebronoyl phytosphingosine, that which contrasts with I3SO3-GalCer with N-nonhydroxy fatty acyl sphingosine as the major molecular species in the other ovarian cancers. In mucinous cystadenocarcinoma, galactosylceramide is found in the relatively high concentration and is also composed of N-cerebronoyl phytosphingosine. In addition, the concentrations of glycolipids with Le(a) and Le(b) antigenicities are significantly higher in mucinous cystadenocarcinoma than those in normal ovary and the other ovarian tumors.

Chromatography, Thin Layer↗
PubMed1992

Expression of factor X and its significance for the determination of paramyxovirus tropism in the chick embryo.

Enveloped animal viruses usually possess a surface glycoprotein which mediates fusion between the viral envelope and host cell membrane, hence enabling the initiation of infection, and its biosynthesis often involves post-translational endoproteolytic activation of the inactive precursor by a host cell protease(s). Therefore, the protease distribution in the host must be critical for determining the viral tropism. We previously isolated from chick embryo a cogent candidate endoprotease of this kind for paramyxovirus infection, and demonstrated its identity with factor X (FX), a vitamin K-dependent serine protease in the prothrombin family which, in general, is synthesized in the liver and circulates as one of the plasma proteases essential for blood clotting. Here, we examined FX expression with specific cDNA and antibody probes in a series of embryonic tissues. Many tissues other than the liver expressed the specific mRNA but, in most instances, the translation products remained inactive zymogen forms. The enzymatically active FXa was detectable only in the allantoic fluid and amniotic fluid, and virus spreading was strictly confined to the tissues in direct contact with these FXa-containing fluids. Thus, the ectopically expressed FXa is probably the major host determinant of paramyxovirus tropism in ovo.

Animals↗
PubMed1992

Bimodal regulation of protein phosphorylation by a ganglioside in rat brain membrane.

Whether or not a ganglioside influences the protein phosphorylation in the rat brain membrane fraction was investigated. Phosphorylation of the 72 kDa protein was significantly affected by the addition of 80 nM GQ1b in vitro, which is far below the reported concentration of gangliosides that affects protein phosphorylation in the neuronal membrane fraction. This action of GQ1b was bimodal: it being not only stimulatory as to the incorporation of phosphate into the 72 kDa protein on incubation of 20 sec, but also as to the release of phosphate from or breakdown of the 72 kDa protein on incubation for more than 5 min. Eighty nM GQ1b did not noticeably affect ATPase in the same fraction. These results suggest that the transphosphorylation of the 72 kDa protein is affected by the interaction of GQ1b with either the responsible enzymes or the 72 kDa protein as a substrate.

Adenosine Triphosphatases↗
PubMed1992

Preferential differentiation of the bile ducts along the portal vein in the development of mouse liver.

The development of bile ducts in the mouse liver was studied histochemically, with special reference to their preferential differentiation around the portal vein. Both portal vein and hepatic vein shared a common origin, the omphalomesenteric vein. In the early development of the liver, haematopoietic cells were predominant around both veins. With the progressive development of intrahepatic bile ducts, the following three steps were observed: cluster formation of type I hepatocytes around the portal vein, formation of primitive bile duct structures and basal lamina, then formation of ducts surrounded by connective tissue structures composed of type I and type III collagens and lectin-binding sites, which were predominant around the portal vein compared to the hepatic vein. These results suggest that the deposition of abundant connective tissue structures around the portal vein is a prerequisite for the cell differentiation and basal lamina formation in the bile duct precursors. A possible mechanism of the aggregation of type I hepatocytes around the portein vein is also discussed.

Animals↗
PubMed1992

Regulation of bone turnover and prevention of bone atrophy in ovariectomized beagle dogs by the administration of 24R,25(OH)2D3.

In order to determine whether the administration of 24R,25(OH)2D3 had any beneficial effect on the regulation of bone turnover and the prevention of bone atrophy, we examined beagles for 31 months after ovariectomy (OVX). Fourteen beagle dogs (8.54 +/- 1.22 kg body wt-b.w.) were divided into four groups. Group 1 (n = 3) was the sham, and Group 2 (n = 3) served as the OVX control. In Group 3 (n = 4) and Group 4 (n = 4), 24,25-dihydroxyvitamin D3(24R,25(OH)2D3) was given daily at dose levels of 2 and 10 mcg/kg B.W., respectively. In Group 4, the dose level was increased to 100 mcg/kg by 17 months. During the experiments, urinary hydroxyproline (U-HPr), serum chemistry, serum bone gla-protein (BGP), and vitamin D metabolite levels were monitored. At the end of the experiment, bone mineral content (BMC) in the 6th and 7th lumbar vertebrae and right femur was determined by single photon absorptiometry. The left iliac bone sample was obtained after tetracycline labeling, and undecalcified sections were observed. In Group 2, excretion of U-HPr increased after OVX and had reached a level of approximately twice the baseline values by 10 months; then it gradually came down to the original level. In Group 3, however, U-HPr excretion remained at the same level as the baseline value, as it did in Group 1. In Group 4, it was remarkably reduced down to 50-60% of the baseline values. Serum BGP level was markedly reduced in Group 4. Serum 24,25(OH)2D levels were markedly increased in Groups 3 and 4.(ABSTRACT TRUNCATED AT 250 WORDS)

24,25-Dihydroxyvitamin D 3↗
PubMed1992

Correlation between detection of anti-viral antibody and histopathological disease activity in an epidemic of hepatitis C.

There was an epidemic of non-A non-B hepatitis in a small area of a town in the central part of Japan, which began with an outbreak of several patients in 1981 and then spread extensively with the result that about one third of the inhabitants showed abnormality in serum liver function tests at the health check performed in 1985. We determined histological diagnoses on that occasion for 167 individuals of the abnormal population and recently assayed antibodies against hepatitis C virus (HCV) for most of their sera left available. Histologically, chronic active hepatitis (CAH) was the major pattern, accounting for 59.3% (99 cases) of the total. Others were chronic persistent hepatitis (CPH) (13.2%), chronic lobular hepatitis (CLH) (16.2%), liver cirrhosis (LC) (6.6%) and fatty liver (4.8%). In the serological studies, the newly developed system to detect antibodies against the viral core protein p 22 was found to be much more sensitive than the conventional system to detect anti C 100-3 antibodies. By using these two methods in combination, we found that 82% were antibody-positive, indicating strong implication of HCV in this epidemic. This was further supported by direct detection of the viral genome in patients' sera by polymerase chain reaction following reverse transcription. We further found a strong correlation between the histological inflammatory activity and the antibody prevalence, since nearly all (97.6%) of the CAH cases were antibody-positive by at least either of the antibody assays, while only about 50% were positive in the less active cases such as CPH and CLH.

Base Sequence↗
PubMed1992

A pathological and immunohistological case report of fatal infectious mononucleosis, Epstein-Barr virus infection, demonstrated by in situ and Southern blot hybridization.

We present an autopsy case of 20-month-old boy who had a fulminant course of infectious mononucleosis, with severe hepatic failure. Autopsy revealed marked infiltration of immunoblasts in the lymph nodes, liver, spleen, thymus and kidneys. We identified a large number of Epstein-Barr virus (EBV) genomes in the immunoblasts of the lymph nodes, liver and spleen by in situ hybridization. EBV genomes were also detected in the liver and spleen by Southern blot hybridization. Histology of the liver revealed diffuse feathery degeneration of the hepatocytes. However, EBV genomes were not detected in the hepatocytes by in situ hybridization and monoclonal antibody studies. Immunostaining of the autopsy liver specimen revealed a large number of suppressor/cytotoxic T cells (Leu2a positive) in the portal areas and of natural killer (NK) cells (Leu7 positive) in the portal areas and sinusoids of the liver. We therefore suggest that the hepatocellular damage was not caused by the viral replication in the hepatocytes but was mainly caused by the abnormal killer cell activity of the suppressor/cytotoxic T cells and NK cells.

Blotting, Southern↗
PubMed1992

Magnificent expression of asialo GM1 on thymus cells and spleen T cells of the musk shrew, Suncus murinus.

The expression of asialo GM1 (GA1) was observed on almost all thymocytes from young musk shrew, at the age of 4 weeks by flow cytometric analysis. In adult shrew aged 10 months, the ratio of GA1-negative thymocytes was increased. Among several anti-glycolipid antibodies used, anti-GM1 and anti-Forssman also reacted with the thymocytes. Protein fraction of the thymocytes was analyzed by SDS-PAGE followed by immunoblotting. Anti-GA1 and anti-GM1 showed two bands and one band, respectively, however, their mobilities were different from each other. Anti-Forssman did not stain any protein. The GA1-positive population in spleen T cell fraction was not detected in young shrew but most of the T cells were changed to GA1-positive cells in adult shrew. When mixed lymphocyte culture was performed, the GA1-negative spleen T cells in young shrew were changed to express GA1 marker on their cell surface by differentiation. Abbreviations used were as follows: GA1, Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc-Cer; GM1, Gal beta 1-3GalNAc beta 1-4(NeuAc alpha 2-3)Gal beta 1-4Glc-Cer; Forssman, GalNAc alpha 1-3GalNAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc-Cer.

Animals↗
PubMed1992

Developmental changes of fucosylated glycoconjugates in rabbit dorsal root ganglia.

Developmental changes of the fucosylated glycoconjugates in the dorsal root ganglia (DRG) of the rabbit were investigated histochemically using anti-fucosyl GM1 antibody and Ulex europaeus agglutinin 1 (UEA-1) lectin. Neither anti-fucosyl GM1 antibody nor UEA-1 lectin bound to the neural tubes or to the neural crest on embryonic day 14 (E14). Anti-fucosyl GM1 antibody binds diffusely to the DRG of E25. Large neurons unreactive with anti-fucosyl GM1 antibody appeared at 1 month and increased within 6 months after birth. Schwann cells immunoreactive with anti-fucosyl GM1 antibody came to be limited to the satellite cells surrounding the positive neurons. No staining with UEA-1 lectin was observed in the DRG of E25. Some small neurons became reactive with UEA-1 lectin within 1 month and remained to be so at 6 months after birth. Schwann cells including satellite cells were unreactive with this lectin. Since fucosyl GM1 was detected in the lipid fraction of DRGs from 1-month-old and 6-month-old rabbits, fucosyl GM1 itself should be the antigen molecule recognized by the anti-fucosyl GM1 antibody. Further study is necessary to elucidate the association between these developmental changes of the fucosylated glycoconjugates in DRG and their possible functional roles.

Animals↗
PubMed1992

A novel glycosignaling system: GQ1b-dependent neuritogenesis of human neuroblastoma cell line, GOTO, is closely associated with GQ1b-dependent ecto-type protein phosphorylation.

Previously, we reported that ganglioside GQ1b specifically promoted neuritogenesis of human neuroblastoma cells (GOTO), and also that is specifically stimulated the phosphorylation of several cell surface proteins on the same cells. To disclose the relationship between the two events, we examined them using a novel protein kinase inhibitor, K-252b, which is a derivative of K-252a and cannot pass through cell membrane. K-252b inhibited the GQ1b-dependent neuritogenesis as well as the GQ1b-stimulated phosphorylation. This suggests the direct coupling between the two cell events and the occurrence of a new biosignal transduction system.

Carbazoles↗