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Biomedical subjects

Y Tsukada

Publications and source records attributed to Y Tsukada.

At least 271 records · Page 15Linked to original sources
PubMed1983

Poor myelination in the central nervous system of "dilute-lethal mutant mice" (d1/d1).

The activity of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase), as a marker for myelinogenesis, was measured in different parts of the nervous system of dilute-lethal mutant mice (d1/d1). The activity in terms of micromoles of 2'-AMP formed per milligram of protein of homogenate per minute was found to be exceedingly reduced in the cerebrum, brain stem, and medulla oblongata, slightly reduced in the cerebellum and cervical spinal cord, but not reduced in the thoracic spinal cord and the optic and sciatic nerves. These results clearly indicate that dilute-lethal mutant mice show poor myelination in the cerebrum, brain stem, and medulla oblongata.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1983

Peripheral nervous system of shiverer mutant mice: developmental change of myelin components and immunohistochemical demonstration of the absence of MBP and presence of P2 protein.

Peripheral nerves of the shiverer mouse, which are characterized by the absence of major dense lines and myelin basic proteins in CNS myelin, were analyzed. From subcellular fractionation of sciatic nerves, it was found from the SDS-polyacrylamide gel electrophoresis that the Pl and Pr proteins equivalent to myelin basic protein of CNS and PM protein were missing in the shiverer in both P2A and P3A fractions in which PNS myelin is recovered. No extra bands were observed in any other fractions of the shiverer in place of the absence of the proteins. The activities of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNPase) of P2A and P3A fractions were high, but that of the P3X fraction which floated over 0.32 M sucrose was the highest among the fractions examined in both the shiverer and the control. Developmental analysis of the protein profiles revealed that PO, Pl, Pr and PM proteins increased rapidly from the sixth day postnatally up to the twentieth day after birth in the control. No differences were observed between the shiverer and the control as for PO protein, but Pl, Pr and PM proteins were absent in the shiverer throughout the development. The CNPase activity of total homogenate of sciatic nerve fibers at birth in the control showed high activity comparable to that of the adult value, but there was no significant difference in activity between the control and the shiverer at any stage of development. Immunohistochemical reaction using peroxidase anti-peroxidase method showed that the myelin from the shiverer did not react with the MBP antiserum, while that of the control reacted positively. On the contrary, the myelin from both shiverer and the control reacted positively against P2 antibody.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗
PubMed1983

Faulty development of cortical neurons in the Snell dwarf cerebrum.

In the Snell dwarf motor cortex, area 6 of Caviness, the cell number, the stratification of neurons and the portion of layer-widths were absolutely identical to those of the controls. By means of the Golgi-Cox method modified by Ramon-Moliner, however, the pyramidal neuron was found to have small perikarya, short primary dendrites with sparse branchings, and a low spine density on the dendrites. The corpus callosum of the dwarf contained a reduced number of fibers compared to that of the controls, and the staining for myelin basic protein revealed a considerable reduction of positive-fibers of radiation in this area. The content of Thy-1 antigen in the cerebrum, cerebellum and brainstem, was significantly lower than that of controls, but the monoamine content was normal in the cerebrum and brainstem. From these results, it appears that the Snell dwarf cerebrum shows retarded neuronal growth; a reduction in size of neurons, an underdevelopment of axons and dendrites, and a retarded maturation of spine, in addition to arrested glial proliferation. At present, it is unclear which hormone deficient in these mutants, growth hormone or thyroxine, is the essential potentiator for neuronal growth.

Animals↗
PubMed1983

Postnatal developments of AChE activity in the hippocampus of the reeler mutant mouse.

The acetylcholinesterase (AChE) activity of the hippocampus and the dentate gyrus in the reeler mutant mouse was studied histochemically by the method of Karnovsky and Roots. Developmental studies were done on days 0,3,6,9,12,15,18 and 21 postnatally, and in adults. The adult reeler mouse differs from the normal mouse in that there is no accumulation of the activity at the junction between the stratum lacunosum-moleculare and the stratum radiatum, weaker and divided activity in CA1, and the translocation of the activity to the granule cell zone of the dentate gyrus. The results obtained are considered to be due to the cells' ectopia. But also, other factors such as genesis of the cells in regard to constructing the cytoarchitecture, may influence them. According to the postnatal observations, the developmental pattern of AChE activity in the reeler mouse is about the same as in the normal mouse. AChE-rich cells in the hippocampus showed maximum activity and number from days 12 to 15. The neuropile reactions increased after day 9 in both kinds of mice. The relationship between the movement of the AChE positive neuropiles and cells and their functions are also discussed.

Acetylcholinesterase↗
PubMed1983

Immunohistochemical localization of 2',3'-cyclic nucleotide 3'-phosphodiesterase and myelin basic protein in the chick retina.

Antisera against bovine 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase) and against chick myelin basic protein (MBP) were raised in New Zealand white rabbits. The specificity of CNPase antiserum was examined by Ouchterlony double-immunodiffusion test and immunoadsorption assay. With use of the specific antiserum, immunohistochemical localizations of CNPase and MBP were investigated in the chick retina. Light microscopic immunohistochemical studies have shown that MBP is localized in the optic nerve fiber layer and that CNPase is localized in the optic nerve fiber and photoreceptor layers. Electron microscopic immunohistochemical examinations demonstrated that the myelin-like neural sheaths in the optic nerve fiber layer were clearly stained by both antisera, whereas the membranes of the Müller cell were not stained. In the photoreceptor layer, membranes of the inner and outer segments of rod and cone photoreceptor cells were intensely stained by CNPase antiserum. However, these portions were not stained by MBP antiserum. Membranes of bipolar cells, amacrine cells, horizontal cells, and ganglion cells were not stained by either antiserum.

2',3'-Cyclic-Nucleotide Phosphodiesterases↗
PubMed1983

Protein synthesis and tumorigenicity of the cytoplasmic hybrid between rat yolk sac tumor and mouse fibroblastic cell line.

Cytoplasmic hybrid (cybrid) cell lines were formed by fusing whole cells of rat yolk sac tumor cell line (EST-II) with cytoplasts of mouse fibroblastic cell line (B-82cap), a variant of mouse L cell line that is deficient in thymidine kinase (TK-) and resistant to chloramphenicol (capr). The cybrid cell line with the nucleus of EST-II and cytoplasma of B-82cap was successfully obtained using double selection with HAT and chloramphenicol-containing medium. The cybrid's ability to synthesize proteins such as albumin, alpha-fetoprotein, gamma-EST, and gamma-GTP was found to be approximately one-fourth that of the nuclear donor, EST-II, at a early time of growth in culture, but this was followed by a gradual increase during the period of observation. The nude mice undergoing subcutaneous transplantation of 1 X 10(6) cells of EST-II and cybrid were killed by the tumor growth, with the survival time being 56 +/- 11 and 105 +/- 25 days, respectively. The histologic findings of cybrid tumor closely resembled those of the nuclear donor, EST-II. These facts suggest that factors from both the nucleus and cytoplasma will be able to affect the gene expression of the cybrid cell line.

Animals↗
PubMed1983

gamma-Glutamyl transpeptidase of rat liver and hepatoma tissues: an enzyme immunoassay and immunostaining studies.

A sensitive enzyme immunoassay method for rat gamma-glutamyl transpeptidase was developed that was able to quantitate between 5 to 500 ng of the enzyme. The enzyme contents of fetal liver, adult liver, hyperplastic nodules, and various tissues including hepatoma were determined. Normal rat liver contained very little enzyme, while fetal liver and hepatoma tissue contained high levels. The gamma-glutamyl transpeptidase content of the liver was assayed during the process of 3'-methyl 4-dimethyl-aminoazobenzene-induced hepatocarcinogenesis. The content was increased at an early stage, then decreased, and again increased at the stage when hepatoma developed. The change of the enzyme content determined by an enzyme immunoassay was highly consistent with that determined by enzymatic assay. This indicates that the increased activity of the enzyme as previously reported was accompanied by an increased immunoreactive enzyme protein. Immunohistochemical studies on the hyperplastic nodule revealed the presence of gamma-glutamyl transpeptidase in the hepatocyte membrane.

Animals↗
PubMed1983

Effect of a conjugate of daunomycin and purified polyclonal or monoclonal antibodies to rat alpha-fetoprotein on the growth of alpha-fetoprotein-producing tumor cells.

Monoclonal antibodies to rat alpha-fetoprotein (AFP) were produced by hybridization of mouse myeloma cells with spleen cells from mice immunized with rat AFP. The monoclonal antibodies as well as horse anti-rat AFP antibodies were coupled via a dextran bridge to daunomycin. Both types of conjugates were tested for their antitumor activity in vitro and in vivo. They were equally cytotoxic to the rat AH66 hepatoma cell line in culture. Rats challenged with hepatoma cells were treated with the conjugates by either intraperitoneal or intravenous injection. Daunomycin conjugates with horse-anti-AFP and monoclonal mouse anti-AFP were capable of delaying the tumor development more efficiently than were the controls of antibodies or free drug, mixtures of drug with antibodies, and a conjugate of drug and normal Ig. The specific conjugates were considerably more effective when the treatments were given intravenously. The specific conjugates produced 60% long-term survival, whereas the controls only slightly delayed tumor development.

Animals↗
PubMed1983

Comparative study of the sugar chains of gamma-glutamyltranspeptidases purified from rat liver and rat AH-66 hepatoma cells.

A comparative study using hydrazinolysis has revealed that the oligosaccharide pattern of gamma-glutamyltranspeptidase purified from rat AH-66 hepatoma cells is very different from that of the enzyme from rat liver. Studies of oligosaccharides in each fraction have clarified the structural basis of the difference found in the sugar chains of the two enzymes. The sugar chains of the liver enzyme were all acidic, while 28% of those of the hepatoma enzyme were neutral, the latter being composed of high-man-nose-type and complex-type sugar chains. Three prominent structural differences were found in the acidic sugar chains of the two enzymes: (a) the sugar chains of the liver enzyme have complete outer chains, Gal beta 1 leads to 4GlcNAc beta 1 leads to, while many of those of the hepatoma enzyme have incomplete outer chains without galactose (Gal); (b) the Gal beta 1 leads to 4GlcNAc beta 1 leads to Gal beta 1 leads to 4GlcNAc beta 1 leads to group is found in the sugar chains of the liver enzyme but not in those of the hepatoma enzyme; (c) more than 40% of the sugar chains of the hepatoma enzyme contain bisect N-acetylglucosamine (GlcNAc) residue which is not found in those of the liver enzyme. Furthermore, the total number of asparagine-linked sugar chains in one molecule of hepatoma enzyme was about 4 times that found in one molecule of liver enzyme.

Acyltransferases↗
PubMed1983

Evidence for the presence of a precursor form to gamma-glutamyl transpeptidase in cultured yolk sac tumor cells.

The biosynthesis of gamma-glutamyl transpeptidase was studied in a yolk sac tumor cell line. Cell suspensions were labeled with [14C]leucine; immunoprecipitates were obtained with anti-gamma-glutamyl transpeptidase antibody and analyzed on SDS-polyacrylamide gel electrophoresis++. A radioactive 80 000 dalton peak and peaks identical to heavy and light subunits were detected in the immunoprecipitates from the extract which was labeled for 15 min. After 45 min labeling, the 80 000 dalton species disappeared, although the two subunits were still observed. Tunicamycin-pretreated cells were labeled with [3H]glucosamine and [14C]leucine for 3.5 h. The 80 000 dalton species was glycosylated, and accumulated to a great degree compared to non-treated cells.

Animals↗
PubMed1983

[Studies on antibodies against rat and mouse tumors: its application to therapy].

An experimental study using antibodies against tumor-associated antigen(s) of various tumor systems in rats and mice is described. Monoclonal antibodies against the variety of tumor systems may be a useful tool for detecting tumor-associated antigen(s) on the cell surface of tumor cells but in case of highly purified antigen, conventional polyclonal antibody having high antibody titer may still be effective for therapeutic application in experimental systems. The conjugate of antibody with anticancer drugs or toxins may be the most effective compound for therapy since the antibody-homing effect will synergistically increase the cytotoxic activity of drugs or toxins against target tumor cells.

Animals↗
PubMed1983

Association of thyroid carcinoma with malignant lymphoma.

Radiation-associated thyroid carcinoma is of clinical importance in modern radiation therapy of both Hodgkin's disease (HD) and non-Hodgkin's lymphoma (NHL), because anatomically the thyroid is often in the radiation field. We have reviewed the records of HD and NHL patients seen at Roswell Park Memorial Institute (RPMI) between 1910 and 1960 to determine associated occurrence of thyroid cancer. Radiation therapy was the major therapeutic modality with the occasional use of single agent chemotherapy with nitrogen mustard, triethylene melamine (TEM), chlorambucil and prednisone. There were 519 patients with HD and 863 with NHL. The thyroid glands of 439 (84%) HD and 544 (63%) NHL patients were included in the field of radiation. The mean age of patients with HD was 39 yr while for those with NHL, it was 53 yr. The mean survival in HD was 4.2 yr and in NHL 3.8 yr. There were three cases of thyroid cancer among the HD patients occurring 31, 44 and 48 yr, respectively, after radiation therapy. When compared with the number of thyroid cancers expected to develop, the incidence was significantly greater (p less than 0.005). In contrast, three NHL patients were found to have thyroid cancer at the time of surgery or postmortem examination. This number is again greater than expected in such a population (p less than 0.005); however, in only two cases could the cancer be considered as a sequela to NHL treatment. In all three cases the cancer turned out to be subclinical thyroid carcinoma, incidentally found at surgery or autopsy. One of the patients is still alive without evidence of either disease. The reason for this difference between patients with HD and NHL treated with a similar principle is unclear. Some of the factors contributing to this difference may include: the younger age of HD patients at diagnosis; the longer survival of patients with HD as compared with those with NHL; differences in the sites of radiation and type of treatment given; and possible differences in immunological status between the two groups.

Adolescent↗
PubMed1983

Cytotoxic effects of daunomycin-fatty acid complexes on rat hepatoma cells.

The anthracycline antibiotic drug daunomycin has been coupled to fatty acids through formation of a peptide bond with the amino group of its lyxose residue. The arachidonic (C20:4) and docosahexaenoic (C22:6) acid derivatives showed potent in vitro and in vivo cytotoxic activity against rat hepatoma cells producing alpha-fetoprotein. With the exception of the acetate derivative, the complexes with saturated fatty acids showed no activity. The in vivo toxicity of the free daunomycin is markedly diminished when present in the form of these derivatives. The antitumor activities of the polyene fatty acid complexes appear to depend upon the high degree of affinity of alpha-fetoprotein for these acids. These results strongly suggest the use of daunomycin or other cytotoxic drug:polyene fatty acid complexes in the therapy of human tumors producing alpha-fetoprotein.

Animals↗
PubMed1982

Oligodendrocyte abnormalities in shiverer mouse mutant are determined in primary chimaeras.

There is increasing interest in hereditary dysmyelinating mutant mice such as jimpy, quaking, shiverer and twitcher, as animal models for leukodystrophy in man. These mutants are characterized by severe tremor and tonic convulsions. Shiverer is an autosomal recessive mutant which displays abnormal and poor myelination of the central nervous system and is genetically different from the other dysmyelinating mutants. Despite many reports on the morphological and chemical changes which occur in shiverer mice, the pathogenesis of the abnormal and poor myelin formation is unknown. We have now produced chimaeras by aggregation of eight-cell-stage embryos from wild-type and shiverer mutants. Analysis of the white matter of the chimaera suggests that the oligodendrocyte is responsible for the abnormal and poor myelination in shiverer.

Animals↗