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T Momoi

Publications and source records attributed to T Momoi.

At least 145 records · Page 8Linked to original sources
PubMed1983

Alterations of glycolipids of human leukemia cell line HL-60 during differentiation.

Alterations of glycolipids of human leukemia cell line HL-60 during differentiation were investigated. The neutral glycolipids of HL-60 cells are of the lacto-types such as lactosylceramide (LacCer) and lactoneotetraglycosylceramide (nLcOse4Cer). The gangliosides of HL-60 cells consisted of a mixture of the lacto-types and the ganglio-types. Chemical inducers of differentiation, 12-O-tetradecanoylphorbol 13-acetate (TPA) and dimethyl sulfoxide, altered the glycolipid profile; II3-alpha-acetylneuraminyl-lactosylceramide (GM3) increased in amount and LacCer and nLcOse4Cer decreased. Tunicamycin had no effect on the glycolipid synthesis. The GM3 accumulated more than tenfold in the TPA-induced macrophage-like cells. This accumulation could be due to the increased activity of LacCer sialytransferase.

Cell Differentiation↗
PubMed1982

Km defect in neuraminidase of dysmorphic type sialidosis with and without beta-galactosidase deficiency.

Kinetic studies of 4-methylumbelliferyl neuraminidase activity were carried out in cultured skin fibroblasts from patients with various disorders of neuraminidase deficiency. Cell extracts from two patients with dysmorphic type sialidosis of infantile onset, with isolated deficiency of neuraminidase activity, and three patients with dysmorphic type sialidosis of juvenile onset, with combined deficiency of neuraminidase and beta-galactosidase activities, demonstrated 7-12 times higher apparent Km values than those of normal controls (1.0-1.5 mmol/l as compared with 0.12-0.15 mmol/l). The apparent Ki values for N-acetylneuraminic acid and colominic acid were also increased in the dysmorphic type (7-15 and 7-11 times the normal values, respectively). In contrast, in the normomorphic type, normal apparent Km and Ki values were found for 4-methylumbelliferyl neuraminidase activity in fibroblasts from one patient with isolated neuraminidase deficiency and two patients with combined deficiency of neuraminidase and beta-galactosidase. The altered kinetics in the dysmorphic cases indicates a primary defect in neuraminidase with a secondary deficiency of beta-galactosidase in patients with combined deficiency. It is not clear if the primary defect in the normomorphic cases involves a defect in neuraminidase other than a Km defect or if neuraminidase or both neuraminidase and beta-galactosidase deficiencies are secondary to another defect as yet undetermined.

Cell Line↗
PubMed1982

Substrate-specificities of acid and alkaline ceramidases in fibroblasts from patients with Farber disease and controls.

The specific activity of acid ceramidase (N-acylsphingosine deacylase, EC 3.5.1.23) was measured at pH4.5 in normal fibroblasts and in fibroblasts from patients with Farber disease and obligate heterozygotes. Greater activity was found when the synthetically made ceramide substrates contained shorter-chain fatty acids or higher content of double bonds. Acid ceramidase activities towards N-lauroyl- (C(12:0)), N-myristoyl- (C(14:0)) and N-palmitoyl- (C(16:0)) sphingosine (C(18:1)) were respectively about 38, 26 and 6 times higher than the activity towards the N-stearoyl (C(18:0)) substrate. The activity towards N-linolenoylsphingosine (C(18:3)/C(18:1)), N-linoleoylsphingosine (C(18:2)/C(18:1)) and N-oleoylsphingosine (C(18:1)/C(18:1)) were respectively about 5, 4 and 3 times higher than the activity towards N-stearoylsphingosine (C(18:0)/C(18:1)). The activity towards N-stearoyldihydrosphingosine (C(18:0)/C(18:0)) was about 40% of that towards N-stearoylsphingosine. Fibroblast alkaline ceramidase possessed significant activity only towards ceramides of unsaturated fatty acids, with a pH optimum of about 9.0. Deficiency of acid ceramidase activity in fibroblasts from patients with Farber disease and intermediate activities in obligate heterozygotes were demonstrated with all ceramides examined except for N-hexanoylsphingosine (C(6:0)/C(18:1)), whereas alkaline ceramidase activity was unaffected. Comparative kinetic studies of acid ceramidase activity with N-lauroylsphingosine and N-oleoylsphingosine demonstrated about 5 (2-12)-fold and 7 (4-17)-fold higher K(m) values in fibroblasts from patients with Farber disease as compared with normal controls. N-Lauroylsphingosine, towards which acid ceramidase activity in control fibroblasts was about 10 times higher than that towards N-oleoylsphingosine, may serve as a better substrate for enzymic diagnosis of Farber disease as well as for further characterization of the catalytically defective acid ceramidase.

Acid Ceramidase↗
PubMed1982

Localization of a glycosphingolipid, asialo GM1, in rat immunocytes.

One of the TLMA (rat T-lymphocyte-macrophage-associated antigens) was characterized as asialo GM1, Gal(beta, 1-3)GalNAc(beta, 1-4)Gal(beta, 1-1)-Cer by two assay methods using monospecific anti-asialo GM1 antibody, immunocytotoxicity testing and immunostaining. Nylon column-enriched T lymphocytes (non-adherent cells) were highly cytolyzed by anti-asialo GM1 antiserum and complement as compared with adherent cells (non T cells). Forty % of peritoneal exudate macrophages and 20% of granulocytes were also cytolyzed by anti-asialo GM1 antiserum. On the other hand, 5% of thymic cells and 60-80% of lymph node T cells were immunostained by anti-asialo GM1 antibody. These asialo GM1-positive cells in thymus were found to be localized in the cortico-medulla junction. About 20% of macrophages and 2)% of granulocytes were also immunostained by anti-asialo GM1 F (ab')2 fragment. These results strongly support the previous conclusion that TLMA can be identified as asialo GM1. Asialo GM1 was universally expressed on a certain population of macrophages of various tissues, but not on all of the population. Alveolar macrophages were also asialo GM1-positive.

Animals↗
PubMed1982

Catalytically defective ganglioside neuraminidase in mucolipidosis IV.

Cultured skin fibroblasts from patients with mucolipidosis IV were found to be deficient in neuraminidase activity toward GD1a and GD1b gangliosides radiolabelled in C8 and C7 analogs of their sialic acid residues. Neuraminidase activities toward 4-methylumbelliferyl-N-acetyl-neuraminic acid, neuraminlactose, and radiolabelled neuraminlactitol, fetuin and alpha 1-acid glycoprotein were within the range of normal controls. Fibroblasts from parents of patients with mucolipidosis IV demonstrated intermediate levels of ganglioside neuraminidase activity and normal levels of glycoprotein neuraminidase activity. The residual acidic neuraminidase activity toward GD1a ganglioside in the patients' fibroblasts did not differ from that of controls in its pH optimum and thermostability, but had an abnormal apparent Km which was about 18 times higher than that of the normal enzyme. These findings suggest that mucolipidosis IV is a ganglioside sialidosis due to a catalytically defective ganglioside neuraminidase.

Fibroblasts↗
PubMed1982

Changing plasma and urinary organic acid levels in a patient with isovaleric acidemia during an attack.

Organic acids in plasma and urine of a patient with isovaleric acidemia were measured serially during a severe ketoacidotic attack. Urinary ketone bodies, lactic acid and 2-hydroxy-n-butyric acid changed in parallel with the plasma isovaleric acid concentration, which was correlated closely with the severity of the clinical symptoms. A 2-day lag was observed between the time of the peak plasma isovaleric acid level and that of the highest urinary excretion of 3-hydroxyisovaleric acid, methylsuccinic acid, mesaconic acid and 2-hydroxyisobutyric acid, the total quantity of which amounted to one-third of that of isovalerylglycine on the 4th day of the attack. Urinary isovalerylglycine excretion remained at a plateau for 4 days after the highest level of plasma isovaleric acid was observed. The decrease of urinary hippuric acid excretion during the attack continued until the patient had recovered enough to be able to eat. Benzoic acid administration concomitant with leucine and glycine canceled the effect of glycine in lessening the rise of plasma isovaleric acid concentration after a leucine load.

Amino Acid Metabolism, Inborn Errors↗
PubMed1981

Studies on the nature and cellular distribution of TLMA--a major rat T axis differentiation antigen. Identification as the glycosphingolipid GgOse4Cer (asialo GM1).

The recently detected T axis differentiation antigen, which was provisionally designated as T-lymphocyte-macrophage-associated antigen (TLMA) could now be identified as the neutral glycosphingolipid GgOse4Cer (asialo-GM1). TLMA is not only expressed on lymphocytes on the T lineage and on macrophages of the rat, but also on eosinophilic cells. On erythrocytes, the determinants are only detectable after neuraminidase treatment. Within the cell surface of thymic lymphocytes, the antigen determinant is partly masked by sialic acid residues. Presently, it cannot be decided whether the masking effect is brought about by sialic acid residues of adjacent glycolipid molecules or whether a nonreactive sialylated precursor molecule exists.

Absorption↗
PubMed1981

Glycolipids: receptors for fibronectin?

We have examined the hypothesis that glycolipids might serve as receptors for the cell surface glycoprotein fibronectin using three different biological assay systems. We find that purified solubilized gangliosides inhibit fibronectin-mediated hemagglutination, cell spreading, and restoration of a normal morphologic phenotype to transformed cells. The inhibition is dose-dependent and competitive; hemagglutination by 2 micrograms/ml fibronectin is half-maximally inhibited by less than 1 microM gangliosides. The most effective ganglioside inhibitors generally contain the most sialic acid residues. The isolated oligosaccharide portions of gangliosides retain this inhibitory activity and the oligosaccharides with more sialic acid are more effective inhibitors. A series of other lipids or ganglioside constituents are either less effective or without detectable activity. The more active of these lipids are the more negatively charged phospholipids such as phosphatidyl serine and phosphatidyl inositol. Our results support the hypothesis that the "receptors" for fibronectin on the cell surface either consist of or contain gangliosides or other negatively charged lipids.

Animals↗
PubMed1981

Two siblings, including a fetus, with Tay-Sachs disease.

This report consists of a morphological study on two siblings of Tay-Sachs disease. One is a girl of 3 years of age and the other is a 23-week fetus. In the first case, the nerve cells in the cerebral cortex showed histochemically abnormal accumulation of glycolipids and electron microscopically numerous membranous cytoplasmic bodies characteristic to gangliosidosis. In the fetal case, the nerve cells in the brain stem were well differentiated and here abnormal inclusions were found by histochemical study. The cortical neurons were immature in structure and inclusions were not demonstrated by histochemical study. In electron microscopic study, the cortical neurons also showed a small number of intracytoplasmic inclusions which contained electron dense granules and/or membranous structures. Causes of the differences in amount of abnormal lipid accumulation in the brain stem and the cerebral cortex were discussed.

Brain Stem↗
PubMed1981

(omega-1)-Hydroxymonocarboxylic acids in urine of infants fed medium-chain triglycerides.

Organic acids in the urine of infants fed a formula containing medium-chain triglycerides (octanoic acid 49% and decanoic acid 26% of total fatty acids) were determined by gas chromatography-mass spectrometry. We found a considerable amount of 5-hydroxyhexanoic acid and 7-hydroxyoctanoic acid, but no detectable 9-hydroxydecanoic acid, as well as a large amount of C6-C10-dicarboxylic acid. We believe that such acids are derived, via (omega-1)-hydroxylation, from medium-chain monocarboxylic acid or medium-chain acyl-CoA in the liver cell. The degree of (omega-1)-hydroxylation of medium-chain fatty acids relative to omega-hydroxylation apparently increases as the chain length of the fatty acids decreases.

Dicarboxylic Acids↗
PubMed1980

Pituitary hyperplasia due to hypothyroidism.

Two cases of hypothyroidism with computed tomographic evidence of enlargement of the pituitary gland are reported; in both the enlargement disappeared after treatment. These findings are in agreement with the previously reported observation that an increase of TSH production in primary hypothyroidism may lead to pituitary hyperplasia.

Child↗
PubMed1980

Aggregate formation of gangliosides at low concentrations in aqueous media.

The gangliosides GLac1, GGtri1 and GGtet1 in aqueous medium sediment in the ultracentrifuge as oligomeric aggregates independent of concentration at 10(-3)M to 10(-9)M with the sedimentation constants S20,W of 5.3, 7.5 and 10.0, respectively. If gangliosides dissolved in dimethylsulfoxide were diluted with water, this resulted in aggregates with lower sedimentation coefficients. In the presence of 1M tetramethylurea no sedimentation of gangliosides could be observed in the ultracentrifuge. A ganglioside analogue (gangliosidoide) with two hydrocarbon chains instead of the ceramide moiety shows a similar sedimentation behaviour as the native compound GGtet1. However, a ganglioside analogue with only one aliphatic hydrocarbon chain forms sedimenting aggregates only at concentrations exceeding 10(-3)M.

Brain↗
PubMed1980

Separation and micro-detection of oligosaccharides of glycosphingolipids by high performance cellulose thin-layer chromatography-autoradiofluorography.

A method is described for the microscale characterization of the oligosaccharides of glycosphinglolipids using high-performance cellulose thin-layer chromatography and autoradiofluorography. With this procedure the oligosaccharides of neutral glycosphingolipids as well as gangliosides were analyzed at an average detection of 10 pmol. The method was tested with the known glycolipds from the erythrocytes of man, sheep, rabbit and guinea pig. As a further application small quantities of the as yet unidentified glycolipids of rat erythrocyte ghosts were isolated and their oligosaccharides determined.

Animals↗