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T Tamai

Publications and source records attributed to T Tamai.

At least 19 recordsLinked to original sources
PubMed1997

Development of DNA diagnostic methods for the detection of new fish iridoviral diseases.

A new disease of epidemic proportions caused by fish viruses within the Iridoviridae family inflicts serious damage on red sea breams (Pagrus major) and striped jack (Caranx delicatissimus) populations grown in aquacultures in Japan. A partial segment of the fish iridoviral DNA was directly amplified using the polymerase chain reaction (PCR) with synthetic primers designed from well conserved nucleotide sequences between the frog virus 3 (Ranavirus) and the silkworm iridescent virus type 6. The deduced amino acid sequence from the nucleotide sequence of the PCR fragment demonstrates a high correlation with a partial sequence from the frog virus 3. Using the PCR method with specific primers, we could detect three of four different known types of fish iridoviruses in diseased fishes. To construct more reliable detection methods specific for this viral family, DNA fragments which can specifically hybridize with all of the four known iridoviridae viral DNAs were screened from the genomic library of one iridoviridae strain. The hybridization assay, using a specific fragment which contains regions which are highly homologous with a characterized partial sequence from the frog virus 3, proved to be a reliable diagnostic tool for fish iridoviral diseases.

Animals↗
PubMed1996

A new solid-phase assay system using magnetic force on blood group serology.

A new solid-phase assay system has been developed for the detection of irregular antibodies in plasma and serum specimens. By means of a magnetic indicator cell, we have established a sensitive and easy-to-handle antihuman globulin (AHG) test involving magnetic-mixed passive hemagglutination (M-MPHA). Comparative studies of M-MPHA with conventional AHG tests demonstrated that this is sufficiently sensitive and specific to detect irregular antibodies to red blood cells. Elimination of centrifugation in this test seems to open the way toward new standardization of solid-phase systems.

Biological Assay↗
PubMed1996

[Studies on the synthesis of cholecystokinin A receptor antagonists. IV. Synthesis and cholecystokinin A receptor inhibitory activities of benzimidazole derivatives].

A number of benzimidazole derivatives were synthesized and tested for cholecystokinin A (CCK-A) receptor inhibitory activity in order to study structure-activity relationships. Significant CCK-A receptor inhibitory activities were found in the compounds having carboxyl or tetrazolyl group. As the most preferred compound, 4-(5,6-dichlorobenzimidazol-2-yl)-N-(3-methoxypropyl)-N-pentylg lutaramic acid (4g) was selected.

Alkylation↗
PubMed1995

Enhancement of the binding of triglyceride-rich lipoproteins to the very low density lipoprotein receptor by apolipoprotein E and lipoprotein lipase.

The low-density lipoprotein (LDL) receptor plays a crucial role in cholesterol metabolism. A related protein, designated the very low density lipoprotein (VLDL) receptor, that specifically binds apolipoprotein (apo) E has recently been characterized and shown to be expressed in heart, muscle and adipose tissue and the human monocyte-macrophage cell line THP-1. The VLDL receptor binds and internalizes VLDL and intermediate density lipoprotein from Watanabe heritable hyperlipidemic (WHHL) rabbits as well as beta-migrating VLDL from cholesterol-fed rabbits but not LDL from WHHL rabbits. Chinese hamster ovary (CHO) cells transfected with the rabbit VLDL receptor cDNA have now been shown to bind or internalize VLDL (d < 1.006 g/ml) isolated from fasted normolipidemic human subjects with lower affinity than WHHL-VLDL or rabbit beta-VLDL. However, binding and internalization were markedly enhanced when fasted human VLDL was preincubated with either recombinant human apoE (3/3) or lipoprotein lipase (LPL) in CHO cells overexpressing the rabbit or human VLDL receptor. CHO cells transfected with both the rabbit VLDL receptor cDNA and the human LPL cDNA effectively bound, internalized, and degraded fasted human VLDL without pretreatment. Treatment of heparinase reduced the effect of LPL-mediated binding at 4 degrees C, but the inhibitory effect was lower at 37 degrees C. Pseudomonas LPL also enhanced the binding of human fasted VLDL to the VLDL receptor at 37 degrees C in CHO cells overexpressing the human VLDL receptor. Taken together, LPL causes the enhancement of triglyceride-rich lipoproteins binding to the VLDL receptor via both the formation of bridge between lipoproteins and heparan sulfate proteoglycans and its lipolytic effect. Ligand blot analysis showed that the apparent molecular mass of the VLDL receptor is 118 kDa, which is smaller than that of the LDL receptor. These results indicate that the VLDL receptor recognizes both triglyceride-rich lipoproteins that are also relatively rich in apoE, as well as the remnants of triglyceride-rich lipoproteins after catabolism and the interaction with heparan sulfate proteoglycans by LPL. The VLDL receptor may thus function as a receptor for remnants of triglyceride-rich lipoproteins in extrahepatic tissues.

Apolipoproteins E↗
PubMed1995

Lipid accumulation and foam cell formation in Chinese hamster ovary cells overexpressing very low density lipoprotein receptor.

The rabbit very low density lipoprotein receptor gene was introduced into LDL receptor-negative Chinese hamster ovary cells (ldl-A7). Incubation of the transfected cells with rabbit beta-VLDL (5 to 8 micrograms protein/ml), for 6 days, induced foam cell formation. The cells accumulated lipid droplets visualized by oil red-O staining; the cellular cholesteryl ester and triglyceride content increased two- to threefold. [3H]Oleate incorporation into cholesteryl [3H]oleate was stimulated threefold by incubation of cells with beta-VLDL (20 micrograms protein/ml). Northern blot analysis revealed the presence of VLDL receptor mRNA in rabbit resident alveolar macrophages. Incubation of the macrophages with beta-VLDL (20 micrograms protein/ml) for 24 hours induced foam cell formation but had virtually no effect on VLDL receptor mRNA abundance. These results suggest that the VLDL receptor on macrophages may play an important role in foam cell formation.

Animals↗
PubMed1995

[Low titer cold agglutinin disease due to anti-HI antibody and a review of this disease in Japan].

A 79 year-old Japanese man was admitted because of brownish urine and Raynaud phenomenon. Laboratory data showed mild anemia with reticulocytosis, positive direct Coombs test against anti-C3, elevated level of lactate dehydrogenase, undetectable level of serum haptoglobin and low titer of cold agglutinin (1:256 at 4 degrees C), the immunoglobulin subclass of which was IgM. Cold agglutinin disease is usually associated with very high levels of cold agglutinins, the specificity of which is anti-I. This case had low titer cold agglutinin disease due to anti-HI cold agglutinin.

Adolescent↗
PubMed1995

[Prediction of postoperative pulmonary function using 99mTc-MAA perfusion lung SPECT].

In order to predict postoperative pulmonary function, 99mTc-MAA perfusion lung SPECT and spirometry were performed preoperatively in 52 patients with resectable primary lung cancer; 44 underwent lobectomy, eight pneumonectomy. Local pulmonary function (called local effective volume) was evaluated according to the degree of radionuclide distribution of each voxel in the SPECT images. The total effective volume was defined as the sum of the local effective volume, and the residual effective volume was the total effective volume excluding loss after operation. Predicted pulmonary function (VC and FEV1.0) was calculated by the following formula: Predicted value = preoperative value x percent of the residual effective volume. Postoperative pulmonary function was predicted in the same patients by means of 99mTc-MAA perfusion lung planar scintigraphy and X-ray CT. The patients were reinvestigated with spirometry at one and four months after surgery, and the values were compared with the predicted values. The correlations between the predicted values using SPECT and measured postoperative pulmonary function were highly significant (VC: r = 0.867, FEV1.0: r = 0.864 one month after operation; VC: r = 0.860, FEV1.0: r = 0.907 4 months after operation). The predicted values calculated using SPECT were accurate compared with the predicted values calculated using planar scintigraphy or X-ray CT. The patients with predicted FEV1.0 of less than 0.8 liter required home oxygen therapy. This method is valuable for the prediction of postoperative pulmonary function before the surgical procedure.

Adult↗
PubMed1995

Effects of insulin, insulin-like growth factor-I, and phorbol esters on neutral cholesteryl esterase activity in cultured rat vascular smooth muscle cells.

We investigated the effects of insulin, insulin-like growth factor-I (IGF-I), and phorbol 12-myristate 13-acetate (PMA) on neutral cholesteryl esterase activity in cultured rat vascular smooth muscle cells. Insulin and IGF-I at concentrations between 10(-9) mol/L and 10(-6) mol/L significantly decreased neutral cholesteryl esterase activity in growth-arrested vascular smooth muscle cells in a dose-dependent manner but with no influences on the intracellular concentration of 3',5'-adenosine monophosphate (cyclic AMP). Treatment of cells with KT5720 (10(-7) mol/L to 10(-5) mol/L), a specific inhibitor of cyclic AMP-dependent protein kinase, significantly decreased neutral cholesteryl esterase activity in a dose-dependent manner. Incubation of cells for 6 to 12 hours with PMA (10(-9) mol/L to 10(-6) mol/L), an activator of protein kinase C, significantly increased neutral cholesteryl esterase activity in a dose-dependent manner. However, down-regulation of protein kinase C activity by long-term incubation (18 to 48 hours) with PMA resulted in a significant decrease in neutral cholesteryl esterase activity. Treatment of cells with UCN-01 (10(-7) mol/L to 10(-5) mol/L), a specific protein kinase C inhibitor, decreased the enzyme activity in a dose-dependent manner and completely blocked the activation of the enzyme by PMA. When insulin or IGF-I at a concentration of 10(-6) mol/L was present in the medium containing CL 277,082--an inhibitor of acyl coenzyme A:cholesterol acyltransferase--cellular cholesteryl ester content of the cells significantly increased. In contrast, after the treatment with PMA at a concentration of 10(-6) mol/L in the presence of CL 277,082, the net cholesteryl ester content of the cells significantly declined. These data suggest that both insulin and IGF-I may increase cholesteryl ester accumulation in arterial smooth muscle cells by decreasing arterial cholesteryl ester hydrolysis. The data also suggest that neutral cholesteryl esterase is activated not only by cyclic AMP-dependent protein kinase but also by protein kinase C. Thus growth factors may exert their antilipolytic or lipolytic actions specifically by modulating neutral cholesteryl esterase activity in vascular smooth muscle cells. Neutral cholesteryl esterase of vascular smooth muscle cells may be regulated by recholesteryl esterase of vascular smooth muscle cells may be regulated by reversible phosphorylation, with the phosphorylated form being the active form.

Alkaloids↗
PubMed1994

Increase in neutral cholesteryl ester hydrolase activity produced by extralysosomal hydrolysis of high-density lipoprotein cholesteryl esters in rat hepatoma cells (H-35).

The metabolism of high-density lipoprotein-associated cholesteryl esters (HDL-CE) in liver cells is not well understood. We studied the possible role of lysosomal and extralysosomal pathways on such metabolism by measuring the uptake and hydrolysis of HDL-CE in H-35 rat hepatoma cells. Incubation of cells with [3H]cholesteryl ester-labeled HDL led to the intracellular accumulation of both 3H-free cholesterol and [3H]cholesteryl ester. The ratio of 3H-free cholesterol/[3H]cholesteryl ester increased with an increase in incubation time even in the presence of chloroquine. Because chloroquine did not inhibit the conversion of cholesteryl ester to free cholesterol, the hydrolysis of HDL-CE may have been catalyzed by an extralysosomal enzyme, perhaps by neutral cholesteryl ester hydrolase (NCEH). When we incubated cells with increasing concentrations of HDL, NCEH activity increased. This increase in enzyme activity was not inhibited by the addition of chloroquine. A complex of dimyristoylphosphatidylcholine (DMPC)/apo HDL/cholesteryl ester enhanced the activity as well as native HDL. Neither the DMPC/apo HDL nor the DMPC/cholesteryl ester complex affected the activity, suggesting that apo HDL may be required for the uptake of HDL-CE. The present study demonstrated that the extralysosomal hydrolysis by NCEH is operating in the metabolism of HDL-CE in hepatoma cells.

Animals↗
PubMed1994

[Evaluation of liver function in carbon tetrachloride-damaged rabbits by dynamic SPECT: comparison of 99mTc-GSA and 99mTc-Sn colloid].

Technetium-99m-DTPA-galactosyl human serum albumin (99mTc-GSA) is a new ligand that binds specifically to asialoglycoprotein receptors in hepatocytes. We performed liver dynamic SPECT using 99mTc-GSA and 99mTc-Sn colloid in nine normal control rabbits and 17 chronically CCI4-damaged rabbits (total 29 examinations), and also performed liver function tests (ICGR15, Alb, etc). Using the obtained dynamic SPECT data, we analyzed the liver kinetics of 99mTc-Sn colloid using a one-compartment model (hepatic blood flow [K]) and 99mTc-GSA using a two-compartment model (hepatic blood flow and receptor binding [K1], catabolism [K2]). As the CCl4-treated period increased, K1 decreased most significantly. K1 showed the most significant statistical correlation with the results of liver function tests, ICGR15 (p < 0.0001), Alb, PT, HP, Bil and GPT. Further, only K1 showed a correlation with the hepatic fibrosis of the HAI score. From the present results, liver dynamic SPECT using 99mTc-GSA may be said to provide a novel method for the evaluation of hepatic functional reserve.

Animals↗
PubMed1994

Successful treatment of transfusion-associated graft-versus-host disease.

We present an immunocompetent patient with transfusion-associated graft-versus-host disease (GVHD), in which chimaerism of peripheral blood lymphocytes was demonstrated by analysis of a highly polymorphic genome. The patient was treated successfully with anti-CD3 monoclonal antibody, OKT3 and cyclosporin A. Although it is undoubtedly important to prevent transfusion-associated GVHD by irradiation of cellular blood components, intensive therapy with OKT3 and cyclosporin A in the early phase of onset may be effective for treatment of this potentially fatal condition. The mechanism of the effectiveness of this treatment for transfusion-associated GVHD is discussed.

Adult↗
PubMed1994

[Strongyloidiasis associated with multiple myeloma in Ehime prefecture].

A 76-year-old male with multiple myeloma, who was born and had lived in Ehime Prefecture was admitted to our hospital because of high fever. The chest X-p film showed right middle lobal pneumonia. Eosinophilia was detected and a stool smear examination revealed rhabditis form larvae of the nematode. The filaria form larvae of Strongyloides stercoralis were detected by stool culture. Antibiotics and pyruvinium pamoate were administered to bacterial pneumonia and hyperinfection of the strongyloides, respectively. Consequently, pneumonia and strongyloidiasis were promptly improved. It was considered that he was infected with strongyloides in south-east Asia during World-War II and a little autoinfection of this nematode had continued about 50 years. In addition, it was suggested that hyperinfection of strongyloides resulted from the immunosuppressive state induced by the chemotherapy for multiple myeloma.

Aged↗
PubMed1994

Acute transformation of chronic large granular lymphocyte leukemia into an aggressive form associated with preferential organ involvement.

In most patients with large granular lymphocyte (LGL) leukemia, the disease appears to progress slowly if at all, and no therapy is generally required. We present a patient with CD3+ CD8+ CD16+ LGL leukemia, who showed a benign clinical course for more than 7 months without therapy, but subsequently developed aggressive disease. A feature of considerable interest was the transformation into an acute or aggressive form in this patient affected preferentially the liver and spleen, and was not associated with the hematologic features of the circulating leukemic cells, as assessed by morphologic, phenotypic and molecular analyses. The patient was treated with combination chemotherapy; this resulted in clinical remission with persistence of the abnormal clone in the peripheral blood. The mechanism responsible for the preferential organ involvement and the process of progression from the chronic to the acute form in this case are discussed from the viewpoint of a lymphoproliferative disorder.

Aged↗
PubMed1994

[HDL receptor].

Epidemiological studies have demonstrated that high density lipoprotein cholesterol (HDL-C) is inversely related to the incidence of coronary heart disease morbidity and mortality. In the present paper, we summarized the recently published data on HDL receptor, reverse cholesterol transport, and antiatherogenic effect of HDL particle. Several investigators have reported the apparent molecular weight of HDL binding protein using ligand blotting by radiolabeled HDL and immunoblotting by antibody against the purified binding protein. These results, however, were not consistent among the data reported from several laboratories. In 1992 a cDNA of HDL binding protein (HBP) was isolated from a human fibroblast and a human erythroleukemia cell cDNA library but it does not contain a classical hydrophobic membranes spanning domain. At present, it is reasonable to assume that HBP is different structurally and functionally from a classical plasma membrane receptor. We hope putative HDL receptor will be isolated, characterized and its cDNA will be cloned in the near future. It has been postulated that there are four functional steps in the pathway of reverse cholesterol transport. The main step is CETP-mediated transfer of cholesteryl esters from HDL to the VLDL/LDL fraction. Recent development of molecular biological techniques enable us to make a animal model over expressing apolipoprotein A-I or A-II, namely a transgenic mouse. These models indicated that apolipoprotein A-I has an antiatherogenic effect in vivo but apolipoprotein A-II does not.

Animals↗
PubMed1993

Cloning and expression of flatfish (Paralichthys olivaceus) interferon cDNA.

Fish interferon (IFN) cDNA was first cloned from the cDNA library of immortalized flatfish leukocytes. The clone contains an open reading frame that encodes a 138 amino acid polypeptide including a glycosylation site and a signal peptide containing 30 amino acids. BHK-21 cells transfected with the INF-expression plasmid produced active recombinant IFN (about 16 kDa) which was then purified by WGA agarose affinity chromatography. This recombinant IFN inhibited infection of fish cells with the Hirame (flatfish) rhabdovirus.

Amino Acid Sequence↗
PubMed1993

Purification and characterization of interferon-like antiviral protein derived from flatfish (Paralichthys olivaceus) lymphocytes immortalized by oncogenes.

Flatfish leukocytes were transfected with the expression plasmids of the v-myc, c-myc, c-fos, v-myb and c-Ha-ras oncogenes. Only cotransfection of c-Ha-ras with c-myc or c-fos resulted in complete immortalization of the cells. Interferon-like anti-viral protein was found in the cultured medium of the immortalized lymphocytes. The protein was purified by DEAE-Toyopearl 650 M ion exchange chromatography and WGA agarose affinity chromatography. The protein was a glycoprotein of about 16 kDa. The antiviral activity of the protein was trypsin-sensitive and was fairly stable at pH values from 4 to 8. The protein retained about 60% of the activity even at 60 degrees C and showed a broad antiviral activity for various fish cells and viruses.

Animals↗
PubMed1993

Effects of nicorandil on cell proliferation and cholesteryl ester accumulation in arterial smooth muscle cells in culture.

Ca2+ regulates a variety of cellular mechanisms in vascular cells as well as in platelets. Nicorandil interacts with the intracellular Ca(2+)-activated processes in vascular smooth muscle cells, while Ca2+ channel blockers such as verapamil and diltiazem block voltage-dependent Ca2+ channels. The effects of nicorandil are due to the hyperpolarization of the membrane, interference with mobilization of Ca2+ from the intracellular storage sites, and blockade of receptor-operated Ca2+ channels. In the present study, the effects of nicorandil on cell proliferation and cholesteryl ester accumulation in rat arterial smooth muscle cells in culture were compared to Ca2+ channel blockers. Smooth muscle cells were prepared from rat thoracic aorta, and the rate of proliferation was determined by measuring the cell number and by [3H]-thymidine incorporation into cellular DNA. The effect of nicorandil on cholesteryl ester content in smooth muscle cells was determined by thin-layer chromatography of the cell extracts. Nicorandil at concentrations of 10(-6) to 10(-4) M, as well as Ca2+ channel blockers (verapamil and diltiazem) inhibited the proliferation and DNA synthesis of cultured smooth muscle cells. The acute inhibitory effects on cell proliferation were observed significantly 16 hours after the addition of the three agents in serum-stimulated cells. These effects were dose dependent, both in acute and in chronic treatment with the three agents. Addition of 10(-5) M nicorandil to medium supplemented with 10% serum resulted in a decrease of the net cholesteryl ester content by 18 +/- 1%, while cellular free cholesterol content was the same as control. Similar results were also obtained in the presence of verapamil and diltiazem.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗