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Biomedical subjects

T Takahashi

Publications and source records attributed to T Takahashi.

At least 19 recordsLinked to original sources
PubMed1979

Unique requirements for template primers of DNA polymerase beta from rat ascites hepatoma AH130 cells.

The optimal condition for the rat DNA polymerase beta activity with (rA)n . (dT)12-18 as a template-primer was determined. The activity was remarkably affected by the concentration of the primer, (dT)12-18' and the mixing ratio of (dT)12-18 to (rA)n. DNA polymerase beta requires higher primer concentration (Km = 11.1 microM with respect to 3'-OH of the primer) than DNA polymerase gamma (Km = 0.04 microM) or oncornaviral DNA polymerase (Km = 0.08 microM) and the enzyme represented the maximum activity in the base ratio of 2:1 with (dT)12-18 and (rA)n suggesting the difference in reaction mechanisms of these enzymes. Under the optimized conditions, the specific activity of the near homogeneous preparation of DNA polymerase beta was 1,000,000 units per mg protein.

Animals↗
PubMed1979

Cell surface antigens of human renal cancer defined by autologous typing.

Sera from 28 patients with renal cancer were tested for reactivity with surface antigens of cultured autologous renal cancer cells. Four serological assays were used to survey sera for autologous antibody. Immune adherence, protein A, and C3-mixed hemadsorption assays detected reactivity in a high percentage of patients (80-100%), whereas mixed hemadsorption assays were negative with sera from all but one patient. Reactive sera from six patients were analyzed by absorption tests with autologous, allogeneic, and restricted to autologous renal cancer cells; class 2 antigens, present on certain allogeneic renal and nonrenal cancer cells; and class 3 antigens, found on a wide variety of normal and malignant cell types. The sera of one patient detected class 1, 2, and 3 antigens, the sera of three patients detected class 2 antigens, and the sera of two patients detected class 3 antigens. This analysis of renal cancer, with the recognition of three classes of surface antigens recognized by autologous sera, resembles the results of autologous typing of three other human malignancies: malignant melanoma, acute leukemia, and astrocytoma. Evidence provided by autologous typing of these cancers indicates that class 1 and class 2 antigens are tumor-restricted and that under certain circumstances these antigens are immunogenic for the autologous host.

Adult↗
PubMed1979

G-cell population in antral mucosa of the dog.

The gastrin-cell (G-cell) population in the pyloric antrum of 8 dogs was studied quantitatively by immunofluorescence. The G-cell population was dense in the pyloric antrum and very few cells were seen in the antrocorporal junction. The estimated total number of G cells was (1.66 +/- 0.12) X 10(7) in the pyloric antrum and the greatest number of G cells per unit mucosal surface area was along the greater curvature of the pyloric antrum. Except along the greater curvature, G cells per unit musocal volume were significantly greater in number (P less than 0.05) in the proximal antrum adjacent to the antrocorporal junction that in any other regions distal to it. Differences in mucosal thickness were considered as a causative factor for these differences.

Animals↗
PubMed1979

A case of double pylorus.

Doubling of the pyloric channel is one of the rare anomalies of the intestinal tract. There have been 23 cases of double pylorus that we have been able to find in the literature. As the etiologic aspects of double pylorus the majorities of the cases were thought to be acquired lesions from ulcer disease except three cases. We present a case of double pylorus which seems to be acquired lesion, with a review of the literature.

Aged↗
PubMed1979

Elastin--lipid interaction action in the arterial wall. Part 1. Extraction of elastin from human aortic intima.

Elastin was extracted from human aortic plaque and adjacent grossly normal intima by the following methods: (1) 0.1 N NaOH at 100 degrees C, (2) hot NaOH and 0.2 M EDTA, (3) 5 M guanidine--HCl and collagenase, (4) guanidine--collagenase and dithioerythritol--urea--sodium dodecyl sulfate, (5) guanidine--collagenase and EDTA, (6) 10% NaCl and collagenase, and (7) NaCl--collagenase and EDTA. All elastin samples contained small amounts of carbohydrate and hydroxyproline. The lipid content of non-plaque intimal elastin samples was small (2--3%), whereas it increased to 4--6% in plaque intima. The lipid composition of elastin preparations varied significantly with the extraction procedure. Elastin from plaque intima contained significantly more cholesterol (50--60%) and less triglyceride and phospholipid than elastin of non-plaque intima (30--50% cholesterol). The contents of free and esterified cholesterol were comparable in all preparations. The main phospholipid in all samples was sphingomyelin, which comprised between 50 and 80% of the total phospholipid. Compared with NaOH-purified elastin, the other elastin samples were characterized by an increased phosphatidyl--choline content, while they all contained an almost equal amount of phosphatidylethanolamine. In elastin samples from plaque intima, the polar amino acids were increased, whereas cross-linking amino acids were decreased. The polarity and hydroxyproline content of elastin samples were slightly decreased after treatment with EDTA or dithioerythritol--urea--sodium dodecyl sulfate.

Amino Acids↗
PubMed1979

Toxicological evaluation of arsenic in edible seaweed, Hizikia species.

Young male Wistar rats were fed with chows containing marketed Hizikia preparation. Hizikia-arsenic could be absorbed at the rate comparable to arsenic trioxide, and accumulated primarily in blood. Intake and excretion of arsenic from Hizikia-diet reached a steady state within 4 days of administration as was the case of arsenic trioxide. Biological half-life in blood and urine was also essentially the same in the 2 groups. Rats kept for 3 weeks on the chows containing up to 20% Hizikia did not show significant growth retardation as compared with the controls, while those on 50% Hizikia-diet were markedly emaciated. In a 38-week feeding experiment, 4 groups of rats were given 20% Hizikia-diets made from various Hizikia preparations (final arsenic concentrations; 9, 16, 21 and 21 ppm, respectively). For positive controls, 2 groups were given arsenic trioxide diets (24 and 50 ppm as arsenic). Growth retardation was minimum both in Hizikia and arsenic groups with no relation to the arsenic dose. Changes in hematology, blood biochemistry and pathology of major organs and skin were also essentially negative in all groups. The maximum no-effect level observed in the present study was compared with the possible amount of arsenic taken via seaweed in mankind.

Animal Feed↗
PubMed1979

AU cell-surface antigen of human malignant melanoma: solubilization and partial characterization.

AU antigen is defined by reactions of sera from patient AU with cell-surface antigens of cultured autologous melanoma cells (SK-MEL-28). Past studies established that no available cell type other than AU melanoma expressed AU antigen. By use of antibody inhibition tests for antigen detection, limited papain digestion of AU melanoma cells was found to result in the solubilization of AU antigen along with beta2-microglobulin (beta 2m) and HLA allogeneic and xenogeneic specificities. Comparable papain treatment of other melanoma and non-melanoma cell lines solubilized beta 2m and HLA, but did not result in the release of antigen with AU reactivity. Maximum yield of AU antigen from AU melanoma cells was obtained after very short (5-15 min) digestion times in contrast to the more prolonged proteolysis required for maximum HLA and beta 2m release. AU antigen was not immunoprecipitated by rabbit antiserum against beta 2m or HLA under conditions leading to partial or complete removal of beta 2m and HLA. At least a proportion of the molecules with AU determinants appear to be glycoproteins, as indicated by specific affinity for Lens culinaris hemagglutinin (LcH). After affinity chromatography on LcH-agarose, the specific activity of AU antigen was increased 50-fold. As determined by gel filtration chromatography, AU antigen has a molecular weight in the range of 20,000-50,000.

Antigens, Surface↗
PubMed1979

Definition of a unique cell surface antigen of mouse leukemia RL male 1 by cell-mediated cytotoxicity.

BALB/c x-ray-induced leukemia RL male 1 is strongly immunogenic for (BALB/c x C57BL/6)F1 mice. Transplants of RL male 1 regressed after initial growth, and after tumor regression mice could resist repeated inocula of 10(7) RL male 1 cells. Spleen cells from immunized mice after in vitro stimulation with RL male 1 were cytotoxic for RL male 1 cells in 3-hr 51Cr assays. Pretreatment of immune spleen cells with Thy-1, Lyt-2, or Lyt-3 antisera and complement eliminated cytotoxic activity, indicating that effector cells for RL male 1 lysis are T cells. Tests with other target cells showed little or no cytotoxicity. Analysis of the specificity of T-cell killing of RL male 1 by competitive inhibition assays with unlabeled cells indicated that only RL male 1 could inhibit killing; other BALB/c tumors (13 x-ray or murine leukemia virus-induced leukemias and three myelomas) failed to inhibit lysis of RL male 1. A range of alloantisera and heteroantisera were tested for their capacity to block lytic activity in the absence of added complement. H-2d antisera and Lyt-2 and -3 antisera blocked lysis, the latter at the level of the effector cell. Antisera to other cell surface alloantigens, murine leukemia virus-related antigens, and immunoglobulins did not block RL male 1 lysis. Thus, T cells from mice immunized against RL male 1 recognize an individually distinct or unique antigen that does not appear to be related to any of the serologically defined cell surface determinants of RL male 1. In its restriction to a single leukemia, the RL male 1 antigen resembles the individually distinct antigens of chemically induced tumors and other tumor types of rodents.

Animals↗
PubMed1979

Cell surface glycoproteins of human tumor cell lines: unusual characteristics of malignant melanoma.

Cell surface glycoproteins of human tumor cell lines (melanomas and astrocytomas, and ovarian, bladder, stomach, cervical, laryngeal, and renal cancers) were studied by labelling with 1) neuraminidase-galactose oxidase-[3H]borohydride, 2) galactose oxidase-[3H]borohydride, and 3) dilute periodate-[3H]borohydride. The labeled components were examined by polyacrylamide gel electrophoresis and fluorography. Each tumor type had a distinctive pattern of labeled glycoproteins when the results from both procedures 1 and 2 were considered. Cell surface glycoproteins of malignant melanoma could not be labeled by procedure 2, whereas the other cell lines had at least two major glycoproteins that could be labeled by this method. Very similar profiles of melanoma glycoproteins were labeled by procedures 1 and 3. From these results the conclusion was reached that cell surface glycoproteins of melanomas are substituted with sialic acid so that their D-galactose and/or N-acetyl-D-galactosamine residues are available for oxidation by galactose oxidase only after neuraminidase treatment. An alternative explanation that these sugars are sterically accessible to galactose oxidase only after neuraminidase treatment also has to be considered. All melanoma lines studied were characterized by having two major cell surface glycoproteins with molecular weights of 110,000 and 90,000, respectively. Lines, however, varied considerably in their expression of other components. In particular, heterogeneity was shown in the expression of gp220, a component identified as fibronectin by immunoprecipitation with a specific antiserum, and in the expression of gp37/32, a pair of glycoproteins having the characteristics of la-like antigens. Of the other cell lines studied, astrocytomas most closely resembled melanoma in their glycoprotein profiles. The brain tumors, however, had two or three glycoproteins, including gp110, which could be labeled by galactose oxidase-[3H]borohydride without neuraminidase treatment.

Antigens, Neoplasm↗
PubMed1979

Purification and characterization of two lectins from Aloe arborescens Mill.

Two lectins have been isolated from leaves of Aloe arborescens Mill by salt precipitation, pH-dependent fractionation and gel filtration. One lectin (P-2) has a molecular weight of approximately 18,000, consists of two subunits (alphabeta) and contains more than 18% by weight of neutral carbohydrate. The smaller subunit (alpha) has a molecular weight of approximately 7,500 and the larger subunit (beta) a molecular weight of approximately 10,500. The other lectin (S-1) has a molecular weight of approximately 24,000, consists of two subunits (gamma2) with a molecular weight of approximately 12,000 and contains more than 50% by weight of neutral carbohydrate. An interesting feature of the amino acid compositions of these lectins is the high proportion of acidic amino acids, such as aspartic acid and glutamic acid, and the low proportion of methionine and histidine. S-1 has a strong hemagglutinating activity. On the other hand, P-2 has not only hemagglutinating activity but also mitogenic activity on lymphocytes, precipitate-forming reactivity with serum proteins, one of which is alpha2-macroglobulin, and complement C3 activating activity via the alternate pathway.

Aloe↗
PubMed1979

Difference in the mechanisms of poly(dT) synthesis by DNA polymerases beta and gamma.

Poly(dT) products which were synthesized depending on (rA)n . (dT)12-18 as a template . primer by mammalian DNA polymerases beta and gamma were analyzed by alkaline sucrose gradient centrifugation. The size of the population of poly(dT) chains synthesized by DNA polymerase beta increased slowly and consistently during incubation up to at least 30 min. On the other hand, the product size with DNA polymerase gamma reached the final size (7 s) within 5 min and the number of products increased during further incubation. Comparison of product number per enzyme molecule suggests that DNA polymerase beta acts on multiple primers in a distributive fashion while DNA polymerase gamma completes poly(dT) chains of large size in a one-by-one fashion.

DNA Polymerase II↗
PubMed1979

Demonstration of hepatitis B e antigen in hepatitis B core particles obtained from the nucleus of hepatocytes infected with hepatitis B virus.

Liver tissue infected with hepatitis B virus was homogenized and nuclei were separated by centrifugation. Hepatitis B core particles were obtained from the nucleus by the digestion with pronase followed by ultracentrifugation in a sucrose density gradient. Hepatitis B core particles were then treated with sodium dodecyl sulphate and 2 mercaptoethanol and tested for hepatitis B e antigen (HBeAg) by the haemagglutination method. The antigenicity of HBeAg was clearly demonstrated in hepatitis B core particles so treated, although untreated core particles did not reveal any detectable HBeAg activity. The localization of HBeAg in hepatitis B core particles was further supported by the results of a fluorescent antibody technique. When a frozen section of the liver infected with hepatitis B virus was stained with the specific rabbit antibody against HBeAg labelled with fluorescent isothiocyanate, only nuclei of hepatocytes were stained, in a similar distribution to hepatitis B core antigen visualized by fluorescent antibody against hepatitis B core antigen in a nearby section.

Cell Nucleus↗