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Biomedical subjects

I Ikeda

Publications and source records attributed to I Ikeda.

At least 145 records · Page 8Linked to original sources
PubMed1989

Role of protein phosphatases in malignant transformation.

Many oncogene products are protein kinases and signals are transduced via phosphorylation of proteins. Similarly, protein-dephosphorylation may play a critical role in malignant cell transformation. We have cloned two catalytic subunits of ser/thr protein phosphatase (PP) type 2A, PP2A alpha, and PP2A beta, from a rat liver cDNA library. Both cDNAs encode peptides of 309 amino acids with a difference of only 8 amino acids between the two. All primary hepatocellular hyperplastic nodules or carcinomas, which were induced by a food carcinogen, 2-amino-3-methylimidazo[4,5-f]quinoline, showed up-regulation of expression of the mRNAs of both PP2A alpha and PP2A beta. NIH3T3 cell transformants obtained by introducing activated c-raf, ret-II or Ki-ras oncogenes also showed high levels of PP2A alpha transcripts. Okadaic acid, a non-TPA type tumor promoter, was found to be a potent inhibitor of PP1 and PP2A. Its IC50 for PP1 was much higher than that for PP2A with phosphorylase a as a substrate. When raf and ret-II transformants were cultured with okadaic acid at 8 ng/ml for 2 days, both transformants became flattened and showed strict contact inhibitions. This flat cell morphology was stable for at least one month in the presence of okadaic acid, but in its absence, the cells reverted to their original transformed shape within 7-10 days. Colony formation by raf and ret-II transformants in soft agar was inhibited dose-dependently by okadaic acid; very few colonies grew in the presence of the acid at 8 ng/ml. Okadaic acid had less effect on a transformant of the Ha-ras gene, causing only 50% inhibition of colony formation at 8 ng/ml. The role of protein phosphatases in cellular transformation by certain oncogenes is suggested.

Animals↗
PubMed1989

[A T-cell type non-Hodgkin's lymphoma with a near-triploid karyotype].

A 16 year-old boy of non-Hodgkin's lymphoma (NHL) was reported. Although Hodgkin's disease was suspected by the presence of Reed-Sternberg-like cells and lacunar cells histologically, a diagnosis of NHL was made because of atypism and monoclonality of the background's cells as well as the morphology of invasive cells in the bone marrow. The tumor cells expressed, CD2, CD3, CD4, CD5 and CD7 antigens, which corresponded to the phenotype of helper-inducer T-lymphocytes. In the analysis of their karyotypes, 16 out of 24 cells revealed normal karyotype, while all the rest showed near-triploidy. Common abnormality was identified as trisomies of No. 1, 3, 5, 16, 21 chromosomes, tetrasomies of No. 10, 19, 20 chromosomes, and 4q+, 7q+, 14p+. Multimodal chemotherapy was successful to induce the patient promptly into complete remission. He has been free from the disease for approximately 12 months. Thus far, triploid clones in hematopoietic malignancies have rarely been described. More importantly, the appearance of them in pediatric lymphoid neoplasms has not yet been reported.

Adolescent↗
PubMed1989

Human ret proto-oncogene mapped to chromosome 10q11.2.

Using cosmid clones derived from human ret protooncogene as probes, we determined its chromosome localization by fluorescence in situ hybridization. Two overlapping clones, cret-1 and -2, which were cloned using the most 5' part of human ret proto-oncogene cDNA, hybridized to chromosome 10q11.2. Sixty-three and 52% of the grains obtained by cret-1 and -2, respectively, were localized to the same site. No other specific hybridization site was observed. From these data, we assigned the site of ret proto-oncogene to chromosome 10q11.2, where the possible locus responsible for multiple endocrine neoplasia type 2A (MEN2A) was mapped by linkage analysis using interstitial retinol binding protein cDNA and D10S5. These findings suggest that ret proto-oncogene might be a suitable probe for approaching the MEN2A locus.

Chromosome Mapping↗
PubMed1989

[Mathematical analysis of equilibrium on 2-site immunoradiometric assay using anti-human TSH monoclonal antibody].

A mathematical analysis of equilibrium was adapted on a practical 2-site immunoradiometric assay (IRMA) using 10 murine monoclonal antibodies (Mabs) to human TSH. The affinity constant of 10 Mabs was from 2.5 x 10(8) to 3.3 x 10(10) M-1. The dose-response curves using appropriate combinations of Mab-coated bead and 125I-labeled Mab were compared with the theoretical curves calculated from mathematical analysis of equilibrium. Theoretical curves were directly affected by the affinity constants in which antibodies with higher affinity constants showed higher binding activity of tracer. However, the curves which antibodies have more than 1 x 10(9) M-1 and 1 x 10(10) M-1 for capture antibody and tracer antibody did not show remarkable change, but were similar with the curve obtained from unlimited affinity constant. From these curve, the maximum and minimum detectable dose were approx. 2 x 10(-10) M and 4 x 10(-14) M, respectively. Seven out of 10 experimental curves for TSH showed good consistency with the corresponding theoretical curves which indicated that a mathematical analysis of equilibrium was useful to presume experimental results using monoclonal antibody.

Antibodies, Monoclonal↗
PubMed1988

Age-related changes in lipid metabolism in rats: the consequence of moderate food restriction.

Male Sprague-Dawley rats, 3 weeks of age, received one of the four following dietary manipulations until 9 months of age: group AD, fed ad libitum; group R, restricted to 75% of food intake of group AD; group RAD, restricted until 5 months of age and then fed ad libitum; group ADR, fed ad libitum until 5 months of age and then restricted. The concentration of serum total and HDL cholesterol tended to be higher in group AD than in all groups that had experienced food restriction. Liver cholesterol was higher in groups AD and RAD than in groups R and ADR. Activity of hepatic microsomal hydroxymethylglutaryl-CoA reductase was comparable, whereas sterol synthesis from mevalonate was significantly higher in groups R and ADR than in groups AD and RAD. Cholesterol 7 alpha-hydroxylase activity also tended to be higher in groups R and ADR. It seems likely that hepatic cholesterol homeostasis functions effectively even when moderate food restriction was started after the growing period. In addition, food restriction reduced the ratio of arachidonate to linoleate, suggesting inhibition of the desaturation system.

Aging↗
PubMed1988

Molecular cloning of cDNA for the catalytic subunit of rat liver type 2A protein phosphatase, and detection of high levels of expression of the gene in normal and cancer cells.

A cloned cDNA encoding a catalytic subunit of type 2A protein phosphatase from a rat liver cDNA library was obtained by use of a synthetic oligonucleotide corresponding to the tryptic peptide sequence of the purified enzyme. There was only a single amino acid difference between the deduced amino acid sequence of the clone obtained and those of the catalytic subunits, 2A alpha, of the rabbit skeletal muscle, porcine kidney and human liver enzymes, suggesting that this clone was a rat 2A alpha cDNA. On Northern blot analysis using a cDNA fragment as a probe, three mRNA species were detected in rat liver: a major mRNA of 2.0 kb and a minor one of 2.7 kb under high stringency conditions, and also a 1.1 kb mRNA under low stringency conditions. The 2A alpha gene was found to be highly expressed in various tissues of rat, especially the brain. High levels of expression of the gene were also detected in mouse NIH3T3 cells and their transformants, and in human cancer cell lines as well as a human immortalized cell line.

Amino Acid Sequence↗
PubMed1988

Detection of patients with cancer by monoclonal antibody directed to lactoneotetraosylceramide (paragloboside).

A hybridoma producing monoclonal antibody (H11) directed to lactoneotetraosylceramide (paragloboside) has been established from spleen cells of a mouse immunized with paragloboside. The monoclonal antibody H11 (immunoglobulin M type) was selected from five clones showing different reactivities with paragloboside. The monoclonal antibody was highly specific to paragloboside and lacked reactivity with other glycolipids including glucosylceramide, lactosylceramide, globotriaosylceramide, globotetraosylceramide, gangliotriaosylceramide, gangliotetraosylceramide, and GalNAc beta 1-4[NeuAc alpha 2-3]Gal beta 1-4Glc beta 1-1Cer. However, the monoclonal antibody (H11) was found to bind to lactosamine-containing glycolipids at their terminals, such as i- and I-type glycolipids as well as paragloboside. A two-step sandwich radioimmunoassay method for paragloboside antigen in serum was established by using the monoclonal antibody. The mean paragloboside antigen concentration in the sera from 20 normal individuals was 25.3 ng/ml. If the cutoff value was set at 80.9 ng/ml [25.3 + 2 x 27.8 (SD)], only 1 of 20 healthy controls had an elevated paragloboside value in the serum, whereas sera from 9 of 12 (75.0%) hepatoma, 4 of 10 (40%) pancreatic cancer, 16 of 40 (40.0%) stomach cancer, and 6 of 10 (60%) lung cancer patients had elevated paragloboside values. Sera from 3 of 8 hepatitis patients and 7 of 10 liver cirrhosis patients were estimated to be positive but sera from 16 patients with benign disease had paragloboside levels lower than the cutoff value. A larger amount of the antigen was found in liver metastases from colorectal carcinoma compared to the normal counterpart. The antigen was also detected in the medium of various human cancer cells and meconium. However, the antigen in the sera, medium, meconium, and cancer tissue seemed to be associated with glycoprotein or lipoprotein, because most of the antigen activity was eluted in the void volume fraction on high-performance liquid chromatography with a gel filtration column.

Antibodies, Monoclonal↗
PubMed1988

The second nation-wide survey in Japan of vitamin K deficiency in infancy.

Throughout Japan a total of 543 cases of vitamin K deficiency occurring in infants over 2 weeks of age were reported from January 1981 to June 1985. Of these cases, 427 showed no obvious reasons for vitamin K deficiency; this sort of case is known as "idiopathic vitamin K deficiency in infancy". Another 57 cases had bleeding episodes due to vitamin K deficiency associated with obvious hepatobiliary lesions, chronic diarrhoea, long-term antibiotic therapy, etc; this sort is called "secondary vitamin K deficiency in infancy". The third group, consisting of 59 cases, was made up of the so-called "near miss" type, in which a haemorrhagic tendency, without any obvious clinical haemorrhage, was discovered by Normotest, at the time of mass screening in most cases. In the idiopathic group, 269 cases (63.0%) developed bleeding episodes between the 1st and 2nd months of age, and 387 cases (90.0%) were entirely breast-fed. Intracranial haemorrhage was observed in 353 cases (82.7%) of this group. Moreover, slight elevation of serum transaminase and direct type bilirubin levels were observed in the idiopathic group. Liver dysfunction of unknown origin may play some role in the onset of vitamin K deficiency in infancy.

Alanine Transaminase↗
PubMed1988

Inhibition of cholesterol absorption in rats by plant sterols.

The extent and site(s) of inhibition of cholesterol absorption by plant sterols, sitosterol and fucosterol, were studied in rats. The intragastric administration of a single emulsified lipid meal containing 25 mg [3H]cholesterol and 25 mg of either sitosterol or fucosterol inhibited the lymphatic absorption of cholesterol by 57% and 41%, respectively, in 24 hr. Less than 2% of each plant sterol was absorbed in the 24-hr period. In contrast, neither plant sterol (50 microM) inhibited cholesterol absorption when co-administered with equimolar amounts of cholesterol in phospholipid-bile salt micelles nor was either absorbed from the micellar solution. A series of in vitro studies was conducted to identify the site(s) of plant sterol inhibition of cholesterol absorption and to account for the difference in inhibitory effectiveness of sitosterol and fucosterol. A comparison of the micellar solubility of each sterol alone and in equimolar binary mixtures (to 2.0 mM) revealed that the solubility of individual sterols decreased in the following order: cholesterol, fucosterol, sitosterol, and that in binary mixtures cholesterol solubility was decreased by sitosterol and, to a lesser extent, by fucosterol relative to its solubility alone. A comparison between micellar-solubilized cholesterol and either sitosterol or fucosterol for binding to isolated brush border membranes, intestinal mucin, or for esterification by either cholesterol esterase or acyl coenzyme A:cholesterol acyltransferase revealed moderate to no competition. The data suggest that plant sterols displace cholesterol from bile salt (taurocholate) micelles and that sitosterol is more effective than fucosterol in this capacity.

Absorption↗
PubMed1988

Molecular cloning and characterization of human ret-II oncogene.

A transformant having ret-II was obtained by transfection of NIH3T3 cells with DNA from a human sigmoid colon cancer. Comparison of the restriction map of ret-II with that of proto-ret revealed that the ret-II has rearrangements both 5' and 3' to the sequence coding for the kinase domain. However, only the upstream rearrangement was consistently observed in all transformants, suggesting that the upstream rearrangement resulted in the activation of proto-ret. The recombination point and replaced sequence of ret-II were different from those previously reported for ret (Takahashi et al., 1985). In addition, ret-II does not retain region coding for transmembrane of proto-ret. This rearrangement, however, was not detected in the original tumor DNA by Southern blot analysis.

Animals↗
PubMed1988

Discrimination between cholesterol and sitosterol for absorption in rats.

The intestinal absorption of cholesterol and sitosterol was compared in rats. The intragastric administration of a single emulsified lipid meal containing either 50 mg of [4-14C]cholesterol or [4-14C]sitosterol resulted in the lymphatic absorption of 18.2% and 0.42% of each sterol, respectively, in 6 hr. This difference was unaltered when the mucosal sterol load was equalized by reducing the cholesterol to 1 mg in the emulsified lipid meal while maintaining the same sitosterol load or when the physical state in the lumen was equalized by infusion of a micellar solution containing both sterols into bile-diverted intestine. Lymphatic cholesterol was 90% esterified compared to 12% for sitosterol. Both sterols were associated predominantly (greater than 70%) with the chylomicron fraction. Eighty percent of the chylomicron cholesterol was recovered as ester with the core lipids, while 77% of the sitosterol was recovered as free sterol with the chylomicron coat. In mucosal homogenates at 6 hr, sitosterol recovery was one-eleventh that of cholesterol. When [3H]cholesterol (10 mg) and [14C]sitosterol (10 mg) were co-administered in an emulsified intragastric lipid meal, sitosterol associated with the brush border isolated 2 hr later was one-fifth that of cholesterol. Similar differences were seen when brush border membranes were incubated in vitro with micellar solutions containing either 50 microM [3H]cholesterol or [14C]sitosterol and the relative uptake of each sterol was unaffected by micellar phospholipid type (egg yolk phospholipids, phosphatidylcholine, or phosphatidylethanolamine).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Absorption and transport of base moieties of phosphatidylcholine and phosphatidylethanolamine in rats.

The absorption and transport of the base moieties of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) which were fed to rats were compared. The major absorption site of ethanolamine-labeled PE was proximal jejunum while choline-labeled PC was absorbed almost equally throughout the jejunum. Lysophospholipids, glycerophosphoryl bases and constituent bases were the main digested products in intestinal content. This shows that base-labeled phospholipids were hydrolyzed to water-soluble products as well as lysophospholipids before absorption. The radioactivities from both phospholipids existed mainly in their parent phospholipids and water-soluble products in the intestinal mucosa. The amounts of lymphatic transport of the radioactivities from choline-labeled PC and ethanolamine-labeled PE were 17% and 8%, respectively, at 8 h after administration. The liver in lymph-cannulated rats contained 23% and 48% radioactivity from PC and PE, respectively, suggesting that base moieties of phospholipids, especially PE, were transported mainly via a non-lymphatic route, probably the portal vein, to the liver, as water-soluble products. The radioactivity from both base-labeled phospholipids in the liver was distributed in the parent phospholipids and water-soluble fractions. Ethanolamine-labeled PE was also incorporated into PC in the liver. These results indicate that intestinal absorption and transport of the base moiety of dietary PC and PE are similar; however, their intestinal absorption site and the extent of their separation during transport between the lymphatic and portal systems differ markedly.

Animals↗
PubMed1987

Digestion, absorption and effects on cholesterol absorption of menhaden oil, fish oil concentrate and corn oil by rats.

Adult male rats were surgically provided with a drainage catheter in the left thoracic lymphatic channel and an indwelling duodenal catheter for constant infusion of physiological saline-5% glucose. After an overnight fast, animals were given a single duodenal dose of an aqueous emulsion containing one of the following: oleic acid, corn oil, menhaden oil or a fish oil concentrate (FOC) and [1,2-3H]cholesterol. Digestion and absorption were estimated by recovering the total fatty acids in the thoracic duct lymph over a 24-h collection period (after subtraction of the "baseline" endogenous fatty acids in the lymph). Cholesterol absorption in the thoracic duct lymph was significantly reduced (P less than 0.05) in the presence of menhaden oil or FOC compared to that in the presence of corn oil. With various fat feedings, the major increases in lymph fatty acids were directly related to the dietary fatty acid content. The relative amounts of eicosapentaenoic acid (EPA) and arachidonic acid (AA) in the thoracic lymph were influenced by the lipid content of the emulsion. The EPA/AA ratio in control, oleic acid and corn oil feedings ranged from 0.12 to 0.25. When marine oil was administered, the EPA/AA ratio was 0.78-0.98. The total amount of fatty acids found in the lymph after marine oil feeding was significantly less (P less than 0.01) than that found after corn oil feeding. The results suggested that the digestion and absorption of menhaden oil and FOC were decreased as compared with corn oil. The EPA/AA ratio was increased in the thoracic lymph after dietary fish oil feeding.

Animals↗
PubMed1987

Radioimmunoassay of atrial natriuretic polypeptide in heat-treated human plasma.

In this simple, sensitive radioimmunoassay (RIA) of atrial natriuretic polypeptide (hANP) in human plasma, nonspecific interference is minimized by deproteinizing the plasma by heat treatment at 85 degrees C for 10 min. We directly measure alpha-hANP in the supernates by RIA, with use of antiserum that recognizes the N-terminal region of alpha-hANP. The minimal detectable value was 0.4 pg per tube. The intra-assay CV was 6.6% (n = 8). The mean concentration of hANP in plasma of 54 healthy volunteers was 41 (SD 29) ng/L. Concentrations of hANP in plasma increased after saline infusion and high salt intake for one week in patients with essential hypertension. High concentrations were also measured in patients with renal failure and congestive heart failure. This method, which requires no extraction or purification with column chromatography, is especially useful for simultaneous measurement of several samples.

Atrial Natriuretic Factor↗