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S Sekiguchi

Publications and source records attributed to S Sekiguchi.

At least 19 recordsLinked to original sources
PubMed1992

Effect of verapamil on the class I major histocompatibility complex antigen expression in K562 chronic myelogenous leukemia cells treated with recombinant human interferon-gamma.

The effects of various compounds which modulated the intracellular signal transduction on the induction of class I major histocompatibility complex (MHC) antigens by recombinant human interferon-gamma (rIFN-gamma) were investigated using K562, chronic myelogenous leukemia cells. Class I or class II MHC antigens were not expressed in untreated K562 cells and rIFN-gamma (600 units/ml) weakly induced class I antigens on the cells. Among the compounds tested, verapamil but not the calcium ionophore A23187 enhanced the rIFN-gamma-induced class I antigen expression at both the surface molecule and mRNA levels and enhancement by verapamil occurred in a dose-dependent manner at non-toxic concentrations examined (approximately 50 microM). Verapamil alone had no inducible effect on MHC antigen expression. Deprivation of Ca2+ in culture medium by ethylene glycol-bis(beta-aminoethyl ether) N,N,N',N'-tetraacetic acid (EGTA) could not cause an enhancement of class I antigen induction by rIFN-gamma. Simultaneous exposure of K562 cells to rIFN-gamma (600 units/ml) and recombinant human tumor necrosis factor (rTNF; 1000 units/ml) in combination with verapamil (50 microM) resulted in a further increase of class I antigens in the cells. The expressions of c-myc oncogene in K562 cells were not changed when the cells were treated with rIFN-gamma (600 units/ml) or verapamil (50 microM), either alone or in combination. These results indicate that verapamil synergistically interacts with rIFN-gamma on the class I antigen induction in K562 cells irrespective of c-myc gene expression and that class I antigen induction in this cell line may not be relevant to calcium influx triggered by IFN-gamma.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1992

Oligo-2',5'-adenylate synthetase activity in cells persistently infected with human T-lymphotropic virus type I (HTLV-I).

Spontaneous production of interferon-gamma (IFN-gamma) was shown in several T-lymphoblastoid cell lines persistently infected with human T-lymphotropic virus (HTLV-1). However, the produced IFN-gamma was not always associated with the induction of the antivirus state. The induction of oligo-2',5'-adenylate synthetase (2-5AS) by IFN was studied in five human T-cell lines persistently infected with HTLV-I (MT-1, MT-2, SMT-1, HUT 102 and OKM-2). Four cell lines are able to produce IFN-gamma spontaneously, while the OKM-2 cell line is not. Poor induction of 2-5AS was recognized in three (MT-1, MT-2 and SMT-1) of the four cell lines producing IFN-gamma, though the poor induction was improved after long-term cultivation of cells with IFN-alpha. On the contrary, in the OKM-2 cell line, significant activity of the enzyme was induced by IFN-alpha. Induction of 2-5AS was not correlated with cell growth inhibition, but with the antivirus state. Furthermore, an inverse relationship between IFN-gamma production and 2-5AS induction was demonstrated in these cell lines with the exception of HUT 102 cells.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Oxygen-transport and solution properties of polylipid/Hb vesicles (ARC).

Polymerized phospholipid vesicle encapsulating Hb (polylipid/Hb vesicle) was prepared from a mixture of unsaturated phospholipid, cholesterol and unsaturated fatty acid and polymerization by gamma-ray irradiation. The average radius of resulting vesicles was 203 +/- 39 nm and concentrated Hb (30 wt%) was efficiently encapsulated. gamma-Ray polymerization proceeds theoretically at low temperature (4 degrees C). P50 and oxygen transporting efficiency were adjusted to 40 mmHg and 40%, respectively. Oncotic pressure and solution viscosity can be controlled to the same values as blood.

Blood Substitutes↗
PubMed1992

Studies on the quality control of stroma-free hemoglobin.

Analytical methods for phospholipids and blood group antigen were developed using HPLC-UV and EIA, respectively, for the quality control of SFH. These methods had sensitivities superior to those of conventional assays. In addition, the HPLC method could isolate PS, which might play an essential role in blood coagulation. The above analytical methods were applied to evaluate three representatives SFH preparation methods, 36,000xg centrifugation followed by the filtration with a 0.22 um filter, ultrafiltration with a 100 kd membrane, and filtration with the BMM-40 nm membrane. Both the BMM method and the ultrafiltration method were shown to remove more than 99.7% of phospholipids, and more than 99.99% of blood group antigen. On the other hand, the centrifugation preparation still contained much of both components. The BMM filter was originally developed as a virus removal filter. The virus removal efficiency of the BMM-40 nm was examined with a genetic technique, the PCR method. The BMM-40 nm was demonstrated to remove HB viruses with an efficiency of eight log or more. These results indicate that the BMM is a useful filter to prepare a stroma-free, virus-reduced hemoglobin solution.

Antigens↗
PubMed1992

Development of analytical methods to evaluate SFH.

For the determination of stroma content in SFH, two analytical methods were developed, the HPLC-UV for phospholipids and the enzyme immunoassay for blood group antigen. These analytical methods were applied to evaluate three representative SFH preparations. The 36,000 x g centrifugation method was shown to contain higher amount of stroma components. On the other hand, the BMM-40 nm and the ultrafiltration method with a 100 kd membrane was shown to remove more than 99.7% of phospholipids and almost all of blood group antigen from hemoglobin solutions. These results demonstrated that these analytical methods were very useful in evaluating any highly purified hemoglobin solutions.

ABO Blood-Group System↗
PubMed1992

[Comparable evaluation of serological diagnostic tests (ELISA, IFA and PA methods) for the detection of anti-Borrelia burgdorferi antibody].

We have evaluated the usefulness of the enzyme-linked immunosorbent assay (ELISA), indirect fluorescent antibody assay (IFA) and particle agglutination (PA) method as serological screening tests for Lyme-borreliosis. Serum samples obtained from two patients with Lyme-borreliosis showed marked high antibody titers for Borrelia burgdorferi when measured by these methods. Of the serum of 368 healthy members of the Self-Defense Force in north-eastern Japan screened for the antibody to B. burgdorferi, 8.4%, 3.7%, 4.6% were found positive by the ELISA, IFA, and PA method, respectively. However, Western blot analysis of these "positive" sera demonstrated no identical bands to those seen in the serum from the patients with Lyme-borreliosis. While 85% and 15% of Treponema pallidum hemagglutination test (TPHA)-positive sera (20 samples) showed a false-positive reaction by the ELISA and IFA method, respectively, no cross-reaction to the anti-B. burgdorferi antibody was observed in these sera by the PA method. The analysis of the serum of the patients with autoimmune diseases (rheumatoid arthritis; 11 cases, systemic lupus erythematosus; 46 cases) by the ELISA and PA methods resulted in a cross-reaction to some extent, which suggested that the antibodies produced by autoimmune mechanisms such as the anticardiolipin antibody can cause a cross-reaction to the anti-B. burgdorferi antibody. These findings indicate that the PA and ELISA rather than the IFA method should be recommended for rapid and conventional screening of Lyme-borreliosis and that serum "positive" for the anti-B. burgdorferi antibody determined by these tests should be confirmed by Western blot analysis to negate the cross-reactions.

Agglutination Tests↗
PubMed1992

["Essential laboratory tests" in primary care medicine--experiences in Comprehensive Medicine, National Defense Medical College].

The "essential laboratory tests" were applied to 1,026 new patients visiting the outpatient unit of Comprehensive Medicine, National Defense Medical College, to determine the usefulness of these tests in primary care medicine. The "essential laboratory tests" have contributed to the establishment of the initial diagnosis or confirmation of the "tentative initial diagnosis", and to the estimation of the nature or degree of seriousness of the disease. In addition, other diseases not related to the patient's chief complaint could be screened in 32% of the new patients examined with these tests. The "essential laboratory tests" were also found to be useful for the estimation of the presence of malignant tumors in 12 patients with various kinds of malignancies as well as the estimation or evaluation for such conditions as infection or inflammation, anemia, liver or renal dysfunction, and the ambulatory screening of metabolic diseases including hyperlipidemia, liver or urinary tract diseases. In conclusion, simultaneous performance of the "essential laboratory tests" with the history taking and the physical examination will provide important medical information in primary care medicine.

Clinical Laboratory Techniques↗
PubMed1992

[Usefulness of "essential laboratory tests" for the establishment of the initial diagnosis in new outpatients].

"Essential laboratory tests" advocated by Japan Society of Clinical Pathology were simultaneously performed with the history taking of the present illness and the physical examination in 1,026 new patients visited the outpatient unit of Comprehensive Medicine, National Defense Medical College. We have analyzed the usefulness of the "essential laboratory tests" for the establishment of the initial diagnosis in evaluable 750 patients by comparing the diagnosis made only by the history taking and the physical examination (tentative initial diagnosis) with that included the results of these laboratory tests. The "essential laboratory tests" had contributed to remarkably increased incidences of metabolic and endocrine diseases, liver or biliary tract diseases, renal and urinary tract diseases and anemia after the application of these tests. The initial diagnoses of 61 patients were successfully established by the addition of the "essential laboratory tests" among 157 cases of which tentative initial diagnoses remained undetermined. These tests confirmed the tentative diagnoses in 78 patients, while 78 tentative diagnoses were negated and corrected after evaluation of the results of these tests. Furthermore, the diagnostic tests such as CRP and leukocyte count were useful for the estimation of the nature or degree of seriousness of the disease in 57 patients. In addition, other diseases not related to the patient's chief complaint could be detected in 238 patients (303 total number of diseases) by these tests. These results indicate the usefulness of the "essential laboratory tests" not only for the establishment of more accurate initial diagnosis but also for the screening of the "hidden" diseases such as hyperlipidemia and liver dysfunction.

Adolescent↗
PubMed1992

[Laboratory tests in primary care medicine: "essential laboratory tests" (2). Usefulness of hematological, biochemical and serological tests in diagnosis of new outpatients].

We evaluated diagnostic utility of the hematological, biochemical and serological tests comprised in the "essential laboratory tests" advocated by the Japan Society of Clinical Pathology in 1,026 new patients visiting the outpatient unit of Comprehensive Medicine, National Defense Medical College. Of 750 evaluable patients, 52 showed anemia associated with such conditions as ulcer or cancer of digestive tract, inflammatory disease, or renal failure. Leukocytosis (greater than 9,000/microliters) was found only in 25 of 112 CRP-positive (greater than 0.3 mg/dl) patients, suggesting bacterial infection. Forty-four patients showed hypoproteinemia and/or hypoalbuminemia indicating chronic conditions including liver and inflammatory disease. Elevation of serum creatinine level was found in 4 patients subsequently diagnosed with renal failure, whereas 32 patients demonstrated elevated BUN. After application of the "essential laboratory tests", 97 patients were diagnosed with hyperlipidemia (total cholesterol greater than 230 mg/dl and/or triglyceride greater than 250 mg/dl). Determination of serum enzyme activity was useful not only for the diagnosis of liver dysfunction or biliary tract disease but also for those of hematological malignancies or myogenic disorders; however, in patients with abnormal values of LDH, gamma-GT and ALP, clinical significance was not clarified in 53%, 38% and 59%, respectively. These results indicate that the "essential laboratory tests" are useful in the following aspects of primary care medicine: for (1) estimation of the degree or nature of infection or inflammatory status; (2) classification of anemia and its relation to underlying diseases; (3) evaluation of patient general condition and protein-producible function of liver; (4) evaluation of renal function; (5) ambulatory screening for metabolic diseases such as hyperlipidemia; and (6) diagnosis of liver and biliary tract diseases.

Ambulatory Care↗
PubMed1991

The influence of tumor cell density on cellular accumulation of doxorubicin or cisplatin in vitro.

The effect of tumor cell density on the cellular pharmacokinetics of doxorubicin (DXR) and cisplatin (CDDP) was studied using MOLT-3 human acute lymphoblastic leukemia cells. As determined by the MTT assay, the growth-inhibitory effect of DXR was approx. 40 times lower when cell density was increased from 10(6) to 10(8) cells/ml (positive inoculum effect), whereas little or no influence of cell density was observed in CDDP-induced cell-growth inhibition. As measured by high-performance liquid chromatography using a fluorescence detector, the cellular accumulation of DXR showed 6- and 18-fold decreases after 1 h incubation when the cells were concentrated from 10(6) to 10(7) and 10(8) cells/ml, respectively. Only at low cell density (10(6) cells/ml) did the amount of DXR in the cells increase with increasing exposure times of up to 6 h. The DXR concentration in the supernatant that was separated from a cell suspension showing a density of 10(8) cells/ml fell to 20% of that obtained at 10(6) cells/ml. The metabolites of DXR, including Adriamycinol and Adriamycinone, were not detectable in the cell extracts or supernatants at any cell density examined. In contrast, the cellular accumulation of CDDP calculated from the platinum concentration, which was measured with a flameless atomic absorption spectrophotometer, was essentially identical at all cell densities examined; moreover, extension of the exposure period resulted in a linear increase in the amount of CDDP in the cells. CDDP concentrations in the supernatants were equally retained, irrespective of cell densities. These observations indicate that the positive inoculum effect shown in DXR-induced cell-growth inhibition results from the decreased cellular accumulation of the drug at high cell densities. We found no influence for cell density on the cellular accumulation of CDDP that might be relevant to the therapeutic potentiation of this drug at high tumor-cell density.

Cell Count↗
PubMed1991

A human leukemia cell line made resistant to two folate analogues, trimetrexate and N10-propargyl-5,8-dideazafolic acid (CB3717).

We established a novel human acute lymphoblastic leukemia cell line made resistant to two folate analogues, trimetrexate (TMQ) and N10-propargyl-5,8-dideazafolic acid (CB3717), by sequential exposure of the 200-fold TMQ-resistant cells (MOLT-3/TMQ200) to CB3717. A 30-fold-resistant subline to CB3717 was selected from the TMQ-resistant cells and designated as MOLT-3/TMQ200-CB371730. This double-folate-resistant cell line was 15-fold more resistant to methotrexate (MTX) than MOLT-3/TMQ200; however, TMQ resistance was decreased to 10-fold as compared to MOLT-3/TMQ200. The doubly resistant cells also showed 2-fold cross-resistance to 5-fluorouracil (5-FU). Equimolar concentrations of leucovorin almost completely reversed the inhibitory effect of MTX on the doubly resistant cells and partially that of CB3717 and TMQ; on the other hand, leucovorin enhanced the inhibitory effect of 5-FU. Thymidylate synthase activities demonstrated little or no difference among these three cell lines, being consistent with no overexpression of mRNA for this enzyme in the doubly resistant cells. MOLT-3/TMQ200 cells displayed classical multidrug resistance; sequential development of CB3717 resistance in the TMQ-resistant cells resulted in an enhancement of the multidrug-resistance phenotype and a concomitant increase of MDR1 mRNA. The development of a complex resistance pattern seen in this double-folate-resistant subline indicates intricacy in the study of drug resistance after multidrug chemotherapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

The particle size of hepatitis C virus estimated by filtration through microporous regenerated cellulose fibre.

To estimate the particle size of hepatitis C virus (HCV), a major causative agent of post-transfusion non-A, non-B hepatitis, we filtered plasma or serum samples through microporous cellulose fibres with different pore sizes. The amount of HCV particles in samples before and after filtration was determined by a quantitative reverse transcriptase polymerase chain reaction (PCR) method. Since there is no quantitative biological assay for HCV, except for that in chimpanzees, the HCV titre obtained from the PCR method was used in an equation constructed previously for application to filtration experiments with a flavivirus which is distantly related to HCV. The particle was estimated to be between 30 and 38 nm in diameter, although the possibility remained that larger HCV particles or HCV aggregates with a diameter of more than 39 nm might exist. Double-step filtration through microporous cellulose fibres with a pore size of 35 nm reduced the HCV content to below levels detectable by our PCR method, indicating that it is possible to eliminate HCV particles by simple filtration techniques.

Base Sequence↗
PubMed1991

Antitumor efficacy of doxorubicin in combination with cisplatin on human lymphoma cells at various cell densities in vitro.

The influence of tumor cell density on the antitumor effect of doxorubicin (DXR) in combination with cisplatin (CDDP) was studied in vitro using DND-39A lymphoma cells. DXR was progressively less effective on colony formation inhibition when cell density was increased from 10(5) to 10(8) viable cells/ml (positive inoculum effect), whereas the effect of CDDP was not influenced by cell densities. At a density of 10(5) cells/ml, inhibition of colony formation was virtually identical irrespective of cells being exposed to DXR and CDDP either simultaneously or sequentially. When cell density was increased to 10(7) and 10(8) cells/ml, sequential exposure to CDDP followed by DXR was more active than simultaneous or reversed order of exposure to the two drugs. These results indicate that for DXR-CDDP combination chemotherapy against the cells at high density, the proper sequence of the treatment should be the administration of CDDP followed by DXR, rather than simultaneous or reversed order of exposure. Inoculum effect may be an additional determinant for the rational development of combination chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

[Clinical diagnosis and laboratory data].

Modern medicine can not be practiced without laboratory tests. Laboratory tests play a vital role from the initial stage of clinical examination. The Japanese Society of Clinical Pathology has formed a committee specifically dealing with the effective and economic use of lab tests without missing or duplicating the important tests. As is shown in table 1 in the main text "Essential Laboratory Tests" were initially agreed as those tests a patient should take when visiting a clinic regardless of the complaint. From an early stage, laboratory tests were done simultaneously with history-taking and physical examinations. Then the "Initial Impression" is obtained and "Organ-oriented 1st and 2nd screening tests" and confirmatory tests will be done to make the final diagnosis. To evaluate the validity of the "Essential Laboratory Tests", we performed the tests on 1026 patients who visited our general medicine clinic for the first time. We compared the Initial Impression with or without Essential Laboratory Tests. Cases in which a diagnosis could not be made by history-taking and physical examination were decreased from 17.4% to 8.0% by performing the essential laboratory tests. Diagnoses made without the essential laboratory tests were found to be mistaken in 10.4% and the additional use of the tests was suggested to lead to a more accurate diagnosis. In 110 cases, diseases unrelated to the chief complaints, were discovered. Even for the respiratory tract infection, CRP and WBC count, which were included in the essential laboratory tests, were very informative.

Adolescent↗
PubMed1991

[Evaluation of treatment of lung cancer combined with the disease which has needed a semi-emergency operation].

Six cases of lung cancer combined with the disease which has needed semi-emergency operation, two cases of unstable angina, two of ileus due to colon cancer, one of impending rupture of abdominal aortic aneurysm and one of purulent cholecystitis with cholelithiasis, were discussed. Mean age was 62.0 years (range, 36 to 73); four were male and two were female. Case 1 and 2 were admitted with anterior chest pain, Case 3 with lumbago and abdominal pain, Case 4 and 5 with an abnormal shadow on chest x-ray film and Case 6 with abdominal pain. Of the two with unstable angina, one was operated on with right upper lobectomy during the first months after aorto-coronary bypass. Of the two with colon cancer, one was operated on with right upper lobectomy during about 5 weeks after right hemi-colectomy. Case 3 with abdominal aortic aneurysm operated on with left upper lobectomy during 4 weeks after replacement of abdominal aorta. Case 4 with cholecystitis was operated on with left pneumonectomy during about 3 weeks after cholecystectomy. The postoperative course of 4 cases and the post-chemotherapy condition of 2 cases were uneventful.

Adenocarcinoma↗