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Biomedical subjects

Y Tamai

Publications and source records attributed to Y Tamai.

At least 19 recordsLinked to original sources
PubMed1992

Inhibitory effect of 5-hydroxy-4-(2-phenyl-(E)-ethenyl)-2(5H)-furanone, a novel synthesized retinoid, on azoxymethane-induced intestinal carcinogenesis in rats.

Modifying effects of 5-hydroxy-4-(2-phenyl-(E)-ethenyl)-2(5H)-furanone, a novel synthesized retinoid (KYN-54), on intestinal carcinogenesis were examined in a rat model using azoxymethane (AOM). A total of ninety male F344 rats, 6 weeks old, were divided into 4 groups. Group 1 (20 rats) was fed a diet containing KYN-54 at a concentration of 0.02% for 3 weeks, during which time 2 s.c. injections of azoxymethane (15 mg/kg) were applied and then kept on a basal diet until the end of the experiment (1 year). Group 2 (30 rats) was given azoxymethane as in group 1 and fed the basal diet throughout, without synthetic retinoid exposure. Group 3 (20 rats) was administered KYN-54 at the commencement of the experiment, but not given the carcinogen. Group 4 (20 rats) received a basal diet alone throughout the experiment and served as a control. Intestinal tumors were seen in groups 1 and 2, their incidence and average number in group 1 (74%, 1.07 +/- 0.87) being significantly less than in group 2 (39%, 0.56 +/- 0.78) (P < 0.02 and P < 0.05, respectively). These results suggest that the synthetic retinoid might be a promising chemopreventive agent for intestinal neoplasia.

4-Butyrolactone↗
PubMed1992

Postremission therapy without prednisolone improves survival in adults with acute leukemia.

This prospective randomized clinical trial was to clarify whether postremission therapy without prednisolone (PSL) was more effective than therapy with PSL in improving the 5-year survival of adults with acute leukemia. Thirty consecutive adult patients with newly achieved complete remission were randomized to receive postremission therapy either with or without PSL between September 1985 and September 1988. The patients ranged from 16 to 57 years in age. Patients treated without PSL had a significantly better 5-year survival rate than those receiving PSL according to Kaplan-Meier analysis (53.5% vs 15.3%, p < 0.05). In the group treated without PSL, eight out of 15 patients were alive at 72 months, and seven patients maintained their first complete remission at 72 months. Among patients with acute lymphoblastic leukemia (ALL) who were treated without PSL the median duration of remission was 24 months, and the survival rate at 72 months was 50.0%. On the other hand, the median survival was only 13 months for the 5 patients with ALL treated with PSL. Thus, it is desirable that adults with acute leukemia are treated by postremission therapy without PSL.

Acute Disease↗
PubMed1992

Characteristic distribution of glycolipids in gadoid fish nerve tissues and its bearing on phylogeny.

Glycolipids were isolated from nerve tissues of gadoid fishes including Alaskan pollack and Pacific cod. Their chemical structures were determined by gas-liquid chromatography and gas chromatography-mass spectrometry, and their constituents were analyzed in detail and compared with those of glycolipids from other fish groups. The results revealed that gadoid fish nerve membranes contain peculiar glycolipid molecular species that are distinctly different from those in other teleostean fishes and higher vertebrates. The mole percentage ratio of the four major glycolipids (cerebroside-sulfatide-galactosylglyceride-sulfogalactosylglyce ride) was 48:12:25:15, indicating profound accumulation of glycoglycerolipids. Galactosylglyceride and sulfogalactosylglyceride were primarily of the diacyl type (greater than 90%), the major fatty acids being 16:0 and 18:1. An abundance of glucocerebroside (25 to 55% of cerebroside) and its fatty acid ester (37 to 47% of ester cerebroside) was noted. Cerebroside and sulfatide were characterized by the absence of hydroxy and odd numbered fatty acids, and 24:1 acid was a predominant component of both glucocerebroside and galactocerebroside. Subcellular fractionation revealed that myelin membranes comprised such unusual glycolipid constituents as those seen in whole nerve tissues. A vertebrate whose nerve membranes consist of such peculiar glycolipid molecules has not previously been reported. The characteristics of the glycolipid composition in gadoid fishes are discussed in relation to myelin functions, physicochemical properties of nerve membranes, and the phylogenic significance of this fish group.

Animals↗
PubMed1992

[Favorable prognoses in 24 adult patients with acute leukemia, surviving over five years since 1985].

Since 1985 we have experienced 24 leukemia cases with long-term survival, who were treated with one of three types of postremission therapy. Of them, 20 patients were physically fit for ordinary work and returned to their work as workers or housewives during long-term follow-up period. Two housewives gave birth. We have devised three types of postremission therapy; 1) multidrug combination therapy with gradually longer intermissions (January 1980-March 1983); 2) controlled randomized clinical trial by the Japanese Foundation for the Multidisciplinary Treatment of Cancer, April 1983-March 1985-March 1988). In a group who underwent multidrug combination therapy without prednisolone, 12 of 20 patients who achieved complete remission have shown continued complete remission, as of November 1991, including seven 5-year survivors. These results indicate that improvement of postremission therapy makes it possible for adult patients with acute leukemia to survive 5 years or longer.

Adolescent↗
PubMed1992

[Bleeding time].

Bleeding time indicates the interaction of the platelets with the damaged vessel wall and the subsequent formation of the primary hemostatic plug. Bleeding time has been widely used in the diagnosis of bleeding disorders, especially thrombocytopenia, abnormalities in platelet function, vascular disorders, and von Willebrand's disease. There are a number of methods to perform the bleeding time test, but there are significant problems concerning sensitivity, specificity, and reproducibility. To study the inhibitory effects of monoclonal antibodies (anti-vWF, anti-GPIb, and anti-GPIIb/IIIa) on primary hemostasis, these antibodies were infused to normal pigs. Anti-vWF and anti-GPIb antibodies markedly prolonged the bleeding time and inhibited hemostatic plug formation. The anti-GPIIb/IIIa antibody completely inhibited ADP-and collagen-induced platelet aggregation, but no or only mild prolongation of bleeding time was observed. The quantitative bleeding time which measures both the time and the amount of blood loss is useful in the diagnosis of hemorrhagic disorders and in judging the efficacy of the treatment. It will provide important information to understand the mechanism of primary hemostasis.

Animals↗
PubMed1990

Stabilization of tumor antigens by chemical modification with diethyl pyrocarbonate.

C3H mice were immunized with MH134 tumors modified with two different chemicals, DEPC and TNBS, and the tumor-neutralizing activities of the spleen cells were examined after separating the cells by a Nylon-wool column, plastic dish, or treatment with specific antibodies (anti-mouse IgG and anti-mouse theta sera). The effector cells induced in mice by immunization with TNBS-treated tumors were T cells. In contrast, in the case of tumors modified with DEPC, macrophages were the major effector cells. The effects of chemical modification on the solubilization of cell surface proteins was also examined. DEPC inhibited solubilization of specific proteins from tumor cell surfaces, while TNBS did not have such an effect on the solubilization of proteins. These results indicate that the antitumor response in mice primed with DEPC-modified tumor is different from the case of TNBS-modified tumors, and that the immunological significance of chemical modification with DEPC is supposedly due to the stabilization of antigenic proteins on the tumor cell surface.

Animals↗
PubMed1990

Identification and characterization of a thermolabile antigen (TLAa, enolase) in Saccharomyces cerevisiae.

Five kinds of proteins of Saccharomyces cerevisiae were recently purified to a homogeneous state and identified as yeast cell surface antigens (TLAa, TLAb, TLAc, TLAd, and TLAe), but their physiological functions remained uncertain. In this paper, TLAa was identified as a yeast enolase (EC 4.2.1.11) from the following evidence: (1) molecular weights and amino acid compositions of both proteins were similar, (2) the N-terminal 22 amino acid sequences of both proteins were the same (3), TLAa had enolase activity, and (4) the authentic yeast enolase gave a positive reaction with anti-TLAa serum in the Ouchterlony immunodiffusion test and the immunoblotting test. Two isoproteins of TLAa (enolase) were separated by non-denatured polyacrylamide gel electrophoresis and detected by immunoblotting with anti-TLAa serum. The contents of the two isoproteins varied depending on the following culture conditions: glucose starvation, growth in the presence of non-fermentable carbon sources, and growth in media containing sodium chloride and 2-deoxyglucose. The contents did not vary, however, with heat shock treatment or with growth in media containing sodium azide, tunicamycin, or sorbitol. These results showed that TLAa was a cytoplasmic antigen, and that its synthesis was regulated by some environmental stresses.

Amino Acid Sequence↗
PubMed1979

Neutral lipid and sphingolipid composition of the brain of a patient with membranous lipodystrophy.

Lipids were extracted from brains of a patient with membranous lipodystrophy (ML) and three normal patients and the neutral lipid and sphingolipid constituents were investigated. The storage of a large amount of free fatty acid was observed in the ML brain, but no cholesterol ester was found. Total lipid, cholesterol and cerebroside contents were slightly decreased in the white matter of the ML brain. The composition of free and sphingolipid fatty acids did not differ between ML and normal brains.

Adult↗
PubMed1979

Creutzfeldt-Jakob disease--alteration in ganglioside sphingosine in the brain of a patient.

Gangliosides isolated from the brain of patients with Creutzfelt-Jakob (C-J) disease were analyzed. The ganglioside current was abnormally low, and the percentage distributions of individual gangliosides and the long-chain base compositions were abnormal. The C20-sphingosine contents of all the ganglioside fractions were low. Abnormalities in ganglioside long-chain bases in adult human brain have been reported previously only in patients with inherited metabolic disorders. These abnormalities in C-J disease seem to be closely related to the cause of the disease.

Brain Chemistry↗
PubMed1979

Lipid composition of brain in a patient with mental retardation due to encephalopathy in an infantile period and one due to homocystinuria.

The lipid compositions of brains of a patient with etiologically unknown encephalopathy (ECP) in an early infantile period and a patient with homocystinuria (HCU) were investigated. In the ECP brain the total lipid content and all lipid classes decreased and the degree of the reduction was more conspicuous in the gray matter than in the white matter. The ganglioside distribution was altered in the ECP brain and the ganglioside long-chain base composition was the infantile pattern. It was shown that damage inflicted on an immature brain leaves persistent effects on lipid metabolism in the course of future brain development, resulting mental and neurological dysfunction. The HCU brain retained almost a normal lipid composition. Among disorders of amino acid metabolism it was found that HCU did not significantly affect lipid metabolism in the brain.

Adult↗
PubMed1978

Effect of immunoglobulin G on membrane-bound enzyme activity of sarcoma 180 cells.

Changes in the activity of membrane bound ATPase of Sarcoma 180 cells caused by immunoglobulin G (IgG) of anti-Sarcoma 180 was investigated in relation to the incorporation of amino acid by the cells. Enzymatic activity of ATPase was increased up to 160% of the original activity upon incubation of the cell with IgG. Kinetic studies showed that IgG did not change the affinity of this enzyme for the substrate, but exerted influence upon catalytic efficiency of the enzyme. The rate of incorporation of leucine into Sarcoma 180 cells was also affected by IgG, as observed in the effect of IgG on the enzymatic reaction of the cells.

Animals↗
PubMed1978

Biochemical characterization of the submicrosomal membrane of the rat brain. Selective solubilization of the components of the light smooth-surfaced membrane by lysophosphatidylcholine.

The light smooth-surfaced membrane, one of the three membrane fractions derived from the rat brain microsomal fraction, was fractionated into its soluble and insoluble parts by the use of lysophosphatidylcholine and the chemical composition of these was investigated. Under the condition whereby the maximal amount of the membrane protein was solubilized by lysophosphatidylcholine (0.5% lysophosphatidylcholine at 37 degrees C for 10 min), the insoluble residue, which accounted for approximately 30% of the membrane protein, was ultracentrifugally homogeneous and showed a granular structure under the electron microscope. The lipid composition of the soluble and insoluble fractions, as well as their protein composition, revealed a preferential and limited solubilization of the constituents of the membrane by lysophosphatidylcholine.

Animals↗
PubMed1978

Selenium protection against mercury toxicity: high binding affinity of methylmercury by selenium-containing ligands in comparison with sulfur-containing ligands.

In determining the protection of selenium against mercury toxicity, the binding affinity of methylmercury by various selenium-containing ligands was investigated by proton magnetic resonance (PMR) spectroscopy. The most striking feature was the small J199Hg-1H value of the selenocysteamine- and selenocysteine-methylmercury complexes, namely, the high affinity of the selenohydryl group to the mercury in comparison with those of the sulfhydryl and amino groups. The order of binding affinity of the coordination groups toward methylmercury is clearly SeH greater than SH greater than or equal to Se-Se greater than NH2 greater than S-S, SeCH3, SCH3. A definite correlation was found to exist between the mercury-proton coupling constants and the chemical shifts of methyl groups of the methylmercury complexes. A relationship between the order (Se greater than S greater than NH2) of affinity for methylmercury and the basicity (or electronegativity and covalent radius) of the donor groups was also discussed. These results suggest the high covalency of the CH3Hg-Se bond, which involves dpi-dpi back bonding.

Chemical Phenomena↗