Search PubMed⌕ Search

Biomedical subjects

K Takatsuki

Publications and source records attributed to K Takatsuki.

At least 253 records · Page 14Linked to original sources
PubMed1991

Possible coupling of prostaglandin E2 receptor with pertussis toxin-sensitive guanine nucleotide-binding protein in osteoblast-like cells.

In cloned osteoblast-like cells, MC3T3-E1, prostaglandin E2 (PGE2) stimulated the formation of inositol phosphates in a dose-dependent manner in the range between 10 nM and 10 microM. Pertussis toxin inhibited the effect of PGE2 dose-dependently in the range between 1 ng/ml and 1 micrograms/ml. In the cell membranes, pertussis toxin catalyzed ADP-ribosylation of a protein with an Mr of about 40,000. Pretreatment of membranes with 10 microM PGE2 in the presence of 2.5 mM MgCl2 and 100 microM GTP markedly attenuated this pertussis toxin-catalyzed ADP-ribosylation of the protein in a time-dependent manner. G12 was detected in these cells by immunoblotting with purified anti-G12 alpha antibodies. The results indicate the possible coupling of PGE2 signalling with pertussis toxin-sensitive GTP-binding protein, which is probably G12, in osteoblast-like cells.

Cells, Cultured↗
PubMed1991

[The absence of monocyte-granulocyte antigen expression in a case of AML].

The brief record of a 25 y. o. male patient with AML (FAB M1) is shown, in whom the blast cells did not express any of the 5 myeloid antigens or the other-lineage related antigens, as detected with the monoclonal antibodies. The blast cells were induced to express CD13 antigen after a short-term culture in vitro. This result suggests that CD13 antigen can be expressed virtually by all AML cells, since CD13 antigen is known to cover fresh AML cells at the highest incidence. No unusual clinical feature was noted in this patient as AML case. The collected documentation of antigen-free AML cases seems necessary for the relevant understanding of AML heterogeneity.

Adult↗
PubMed1991

[Seropositivity of anti-HTLV-II antibodies in patients with HTLV-I-associated myelopathy and adult T-cell leukemia].

Dr Kira et al. (Lancet 1991, 338: 64-65) stress the high incidence of the co-infection with HTLV-I and HTLV-II in the HTLV-I associated myelopathy or tropical spastic paraparesis (HAM/TSP) detected by a polymerase chain reaction (PCR). They showed that 67% of HAM/TSP patients and 6% of healthy carriers had the co-infection. They suggested the co-infection might be important for the development of the myelopathy. Recently, we have analyzed the seropositivity of antibodies to HTLV-I and II in Adult T-cell Leukemia (ATL), HAM/TSP and carriers in Japan using SELECT-HTLV (IAF Biochem International Inc., Montreal, Canada). This system was a solid phase enzyme immunoassay utilizing synthetic peptides to differentiate between antibodies to type I and II. We examined 101 samples (31 ATL patients, 20 HAM/TSP and 50 carriers) which were all positive with the particle agglutination (PA, Fujirebio, Tokyo) and ELISA (Eisai, Tokyo). All samples were negative with HTLV-II and positive with HTLV-I. The results of our serological survey suggested that HTLV-II did not associate with the etiology of ATL and HAM/TSP in Japan.

HTLV-II Antibodies↗
PubMed1991

Erythropoietin rapidly reduces phosphorylation of a membrane protein in a murine erythroleukemia cell line.

Erythropoietin (Epo) is a glycoprotein hormone that specifically regulates the proliferation and differentiation of erythroid progenitor cells. The effect of Epo on the phosphorylation of cellular proteins was investigated in a murine erythroleukemia cell line ELM-I-1 which differentiates to produce hemoglobin in response to Epo. The phosphorylation of a prominent 98 kDa phosphoprotein (pp98) (pI approximately 6.5) in the particulate fraction of ELM-I-1 cells decreased markedly upon exposure of the cells to recombinant human Epo. The effect was rapid and transient, occurring within 1 min after Epo exposure, and disappearing within 15-30 min. Interleukin 3, another hematopoietic factor which is known to act also on erythroid progenitors, did not induce this effect. Phosphoamino acid analysis revealed that pp98 is phosphorylated on serine residues. The results suggest that this rapid and transient alteration in protein phosphorylation may serve as critical trans-membrane signal for Epo.

Animals↗
PubMed1991

Usefulness of pulsed Doppler ultrasound in detection of angiographically evident recurrence of hepatocellular carcinoma after arterial embolization treatment.

Because hepatocellular carcinoma treated by transcatheter arterial embolization often regains its size, routine follow-up is necessary. The usefulness of pulsed Doppler ultrasound for detection of this type of recurrence was compared with ultrasonography and computed tomography in 21 such hepatocellular carcinomas. Of 15 hepatocellular carcinomas diagnosed by angiography as showing recurrence, four were detected with ultrasonography and five were detected with computed tomography. Doppler signals were obtained in the peripheral portions corresponding to tumor vessels or stains on angiograms in 14 of these 15 hepatocellular carcinomas, but they were undetectable in six hepatocellular carcinomas with no recurrence. All signals disappeared after transcatheter arterial embolization. One false-negative hepatocellular carcinoma with pulsed Doppler ultrasound showed faint tumor stains on angiograms; these were also negative on ultrasonography and computed tomography. Pulsed Doppler ultrasound may be superior to ultrasonography and computed tomography as a routine procedure to detect the recurrence of hepatocellular carcinoma treated by transcatheter arterial embolization.

Aged↗
PubMed1991

[Simultaneous detection of antibodies for 3 different retroviruses using retrovirus EIA (triple antigen kit)].

We evaluated Retrovirus EIA kit (Roche Co.), in which virus components of three different viruses, HIV-1, HIV-2, and HTLV-I were used antigens. All the specimens from the patients with ATL, HAM, HTLV-I carrier, AIDS and AC, and from HIV-2 infected individuals were found to be positive. Four out of 40 specimens from hemophiliacs not infected with HIV-1 were found out to be positive. These specimens were confirmed to contain antibody against HTLV-I. Pseudo-negative or -positive reactions were not found in this study. Therefore, Retrovirus EIA kit should be evaluated more extensively, for the possible applications for screening of blood donors, and for selecting the sources of blood products as well as for clinical diagnoses.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Immunological and virological status of a hemophiliac infected with human T cell lymphotropic virus type 1 and human immunodeficiency virus type 1, and results of therapy.

The immunological and virological status of three hemophiliacs infected with human immunodeficiency virus type 1 (HIV-1) was monitored for 11 months. One of these patients was also infected with human T cell lymphotropic virus type 1 (HTLV-1), and HIV-1 could be isolated only from this patient among the three subjects. The doubly infected subject had the fewest T4 (helper) lymphocytes and the highest proportion of T8 lymphocytes with DR human leukocyte antigens (DR-Ag). The serum level of HIV-1 antigen increased in this patient during the observation period, and this increase was accompanied by a decrease in the proportion of DR-Ag-positive cells among the T8 lymphocytes. This patient was treated with 800 mg of zidovudine daily for 50 days. With treatment, the nonspecific clinical symptoms improved and the proportions of DR-Ag positive cells among the T8 lymphocytes decreased. Serum levels of HIV-1 antigen decreased immediately when therapy was started but later increased during therapy. In persons infected with both HTLV-1 and HIV-1, HIV-1 seems to proliferate readily.

Adolescent↗
PubMed1991

Human T-cell leukemia virus type I infection as an oncogenic and prognostic risk factor in cervical and vaginal carcinoma.

The seroprevalence of human T-cell leukemia virus type I (HTLV-I) antibody in 6701 healthy females and 226 women with gynecologic malignancies, all living in an adult T-cell leukemia-endemic area in southwestern Japan, was investigated to determine whether HTLV-I infection was a risk factor influencing oncogenesis and prognosis. The seroprevalences in cervical carcinoma patients younger than 59 years and in vaginal carcinoma patients of all ages were significantly higher than in age-matched healthy controls. The ratios of observed to expected HTLV-I seroprevalence in patients younger than 59 with cervical carcinoma and in vaginal carcinoma patients were 2.92 and 7.36, respectively. Among the patients with cervical carcinoma or vaginal carcinoma, the tumor recurrence rate in HTLV-I carriers was significantly higher than that in HTLV-I seronegative patients. Our results suggest that HTLV-I infection may be oncogenic and may affect the prognosis in some patients with cervical or vaginal carcinoma.

Adolescent↗
PubMed1991

[Serum deoxythymidine kinase activity in adult T-cell leukemia].

Serum deoxythymidine kinase activities (s-TK) of the patients with adult T-cell leukemia (ATL), carriers and healthy persons were measured, using a recently developed TK assay with 125I-iodo-deoxyuridine as a substrate. The mean s-TK values were 3.3 +/- 2.7 U/l (n = 21) in normal subjects (HTLV-1(-)), 4.7 +/- 5.0 U/l (n = 35) in carriers, 9.8 U/l (n = 3) in smoldering ATL and 26.7 U/l (n = 6) in chronic ATL. In the patients with acute ATL, the mean s-TK values before and after chemotherapy were 80.9 U/l (n = 2) and 11.6 U/l (n = 4), respectively. In the follow-up studies of the patients with acute ATL, the changes of s-TK levels revealed earlier than those of serum LDH levels. It is suggested that s-TK activity is more useful than LDH as a parameter of monitoring treatment in ATL.

Biomarkers, Tumor↗
PubMed1991

[Biomolecular aspects of adult T-cell leukemia].

ATL (adult T-cell leukemia) is the first human cancer known to be caused by a retrovirus. ATL cells show usually positive for CD2, CD3, CD4, CD25 and HLA-DR, but negative for CD8. They produce a variety of cytokines, including IL-1, IL-2, TNF, ADF and PTHrP. PTHrP is considered to be responsible for hypercalcemia which is frequently observed in ATL. Recently, we reported two unusual cases of HTLV-I associated malignancy; 1) a case of CD4 and 8 double negative tumor affecting mainly gastrointestinal tract and 2) a case mimicking small cell lung cancer. IL-2-toxin, a conjugate of IL-2 and diphtheria toxin, has been prepared as a recombinant product and evaluated for the suppressive effect to ATL cells. Clinical trail of IL-2-toxin is now anticipated.

Antigens, CD↗
PubMed1990

Generation of neutralization-resistant HIV-1 in vitro due to amino acid interchanges of third hypervariable env region.

Antigenic mutants of HIV-1 were isolated from three plaque-cloned viruses by the resistance of the virus to neutralizing mAb 0.5 beta against V3 domain of viral gp120, when the viruses were passaged in the presence of the antibody. However, when chronically infected MOLT-4 cells were treated with 0.5 beta mAb, recovered viruses from the 0.5 beta-treated cells showed no antigenic changes. The extent of genomic variation among antigenically distinct isolates was examined by nucleotide sequencing, which revealed a few base substitutions in 0.5 beta-binding site of all mutants isolated. The predicted amino acid replacements within 0.5 beta reacting epitope (V3 domain) causing the altered antigenicity were also identified for each of three isolates. Particularly, in one of the mutants, the most conserved Gly-Pro-Gly-Arg region located at the center of the V3 domain was changed to Gly-Gln-Gly-Arg. The radioimmunoprecipitation and synthetic peptide analyses revealed that this Pro320----Gln substitution reduced the binding affinity with 0.5 beta, although other mutations observed in the other mutants did not affect the binding affinity in radioimmunoprecipitation. We also observed that nucleic acid substitutions in the V3 domain occurred frequently in the absence of 0.5 beta mAb during our in vitro acute infection system using MT-4 cells.

Amino Acid Sequence↗
PubMed1990

Human T-cell leukemia virus type 1 associated with small cell lung cancer.

A patient with small cell lung cancer (SCLC) whose serum contained high levels of soluble interleukin-2 receptors is reported. Soluble interleukin-2 receptors in the supernatant of cultured SCLC cells obtained from the patient's pleural effusion while he had malignant pleuritis, increased almost linearly from the time of cell seeding. The expression of interleukin-2 receptors (Tac) on the SCLC cells were demonstrated by an immunofluorescence study. However, other lymphocytic markers, including OKT 11, OKT 4, OKT 8, B 1, and B 4, were not found on the cells with the exception of the natural killer cell marker, NKH-1. Southern blot analysis indicated the rearrangement of the T-cell receptor of the cancer cells. Moreover, monoclonal integration of human T-cell leukemia virus type 1 (HTLV-1) provirus in DNA from the cancer cells was also demonstrated. These observations suggest that some SCLC in HTLV 1 endemic areas are associated with HTLV-1.

Biomarkers, Tumor↗
PubMed1990

Constitutive expression of parathyroid hormone-related protein gene in human T cell leukemia virus type 1 (HTLV-1) carriers and adult T cell leukemia patients that can be trans-activated by HTLV-1 tax gene.

Adult T cell leukemia (ATL) is associated with human T cell leukemia virus type 1 (HTLV-1) infection, and almost all ATL patients have the complication of hypercalcemia. To understand the mechanism of the high incidence of hypercalcemia in ATL, we studied the expression of a parathyroid hormone-related protein (PTHrP) gene that has been proposed as a causative factor of hypercalcemia in some solid tumors. The polymerase chain reaction coupled with reverse transcription of mRNA was applied to RNA from peripheral blood mononuclear cells. Cells from all 13 ATL patients examined showed abundant expression of the PTHrP gene, while cells from uninfected normal subjects did not. Significant expression of PTHrP gene was also detected in HTLV-1 carriers without any symptoms and in patients with HTLV-1-associated myelopathy or tropical spastic paraparesis. PTHrP mRNA levels correlated with the number of infected cells that were estimated by the integrated HTLV-1 DNA. These results suggest that HTLV-1-infected cells are expressing the PTHrP gene. This concept was further supported by the finding that the HTLV-1 trans-activator, the tax gene product, caused trans-activation of the PTHrP gene promoter linked to the CAT gene. These observations might explain the general expression of the PTHrP gene in ATL patients and the high incidence of hypercalcemia in ATL.

Base Sequence↗
PubMed1990

Dynamic aspects of thrombus formation in mutant analbuminemic rats.

To elucidate the mechanism for thrombus formation in hypoalbuminemic and hyperlipidemic subjects, the experimental thrombus formation was analyzed in Nagase analbuminemic rats (NAR). The mutant rat reveals similar biochemical findings to those of NS, such as hyperlipidemia. When thrombus was induced in a small branch of the mesenteric artery by inserting a glass micropipette, thrombus formation was observed within 4 min in NAR and Sprague-Dawley rat (SDR). In SDR, the thrombus gradually grew up in size and detached from the inserted glass micropipette within 4 min after its formation. In contrast, the thrombus formed in NAR did not dissociate from the micropipette until 10-13 min after its formation. The maximum size of the thrombus formed in NAR was about 4 times larger than that in SDR. In the presence of fibrin, the plasma samples from NAR inhibited the activity of tissue-plasminogen activator (t-PA) 1.7 times more potently than did SDR plasma. Plasma gamma 2-plasmin inhibitor activity was significantly higher than that in SDR. Albumin significantly enhanced the t-PA-catalyzed activation of plasminogen, suggesting that the serum albumin might contribute, at least in part, to the plasma fibrinolytic activity. Thus, the higher thrombogenic potential in NAR than in SDR might be due to the reduced thrombolytic activity in NAR.

Animals↗
PubMed1990

Determination of N-nitrosodimethylamine in fish products using gas chromatography with nitrogen-phosphorus detection.

A simple and rapid gas chromatographic method for the determination of N-nitrosodimethylamine (NDMA) in fish products is described. NDMA is extracted from a dried sample with methylene chloride, mixed with n-hexane and passed through a silica gel column. NDMA adsorbed on silica gel is eluted with methylene chloride-diethyl ether (7:3) and the eluate is passed through a Sep-Pak alumina A cartridge column, on which NDMA is adsorbed. NDMA is eluted from the cartridge with diethyl ether-methanol (2:1) and the solution is injected into a gas chromatograph with nitrogen-phosphorus detection. This method does not use solvent evaporation and concentration in the clean-up procedure, which eliminates the loss of volatile NDMA and artifactual formation of NDMA in the analytical procedure. The detection limit is 0.5-1 micrograms/kg and recoveries from salted pollack roe spiked at 40 and 4 micrograms/kg were 96.7% [relative standard deviation (R.S.D.) 3.6%] and 85.0% (R.S.D. 6.8%) respectively.

Aluminum Oxide↗