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Biomedical subjects

K Takaki

Publications and source records attributed to K Takaki.

At least 55 records · Page 3Linked to original sources
PubMed1989

Immunocytochemical and ultrastructural studies of the histogenesis of Ewing's sarcoma and putatively related tumors.

The histogenesis of Ewing's sarcoma (EW) and extraskeletal Ewing's sarcoma (EEW) is still disputable. Their relationship to the so-called Askin's tumor, neuroectodermal tumor of bone, and peripheral neuroblastoma remains to be established. In an attempt to clarify these points, immunocytochemical and ultrastructural studies were done on tissues from 14 cases of EW, 4 cases of EEW, and 9 cases of primitive neuroectodermal tumor (PNET) and compared with neuroblastoma and olfactory neuroblastoma. Six tumors categorized initially as EW and EEW on biopsy, turned out to be PNET by extensive histologic and/or ultrastructural observations. Abundant glycogen was recognized not only in 16 of 18 cases of EW and EEW, but also in seven of nine cases of PNET. Fine fibrillar cell processes were seen between tumor cells, at least in limited areas even in cases of EW and EEW. Immunocytochemically, neuron-specific enolase (NSE), neuroblastoma cell surface antigen (NBCA), neuron cell surface antigen (NCSA), and neurofilament (NF) were demonstrated not only in neuroblastoma, but also frequently in cases of EW, EEW, and PNET. The results seem to suggest that EW and EEW represent the most immature forms of neuroectodermal tumor. Electron microscopic study showed predominantly primitive cells with occasional areas of cell processes, neurosecretory granules, and microtubules, suggesting a neuroectodermal origin.

Adolescent↗
PubMed1987

Phosphorylation by protein kinase C of a synthetic heptapeptide bearing a lysine residue on the C terminal side of serine.

A peptide, Ala-Ser-Gly-Ser-Phe-Lys-Leu, which corresponds to Ala103-Leu109 of Hl histone, was synthesized and tested as substrate for protein kinase C. The serine residue at position 4 was phosphorylated specifically. Another peptide lacking the lysine at position 6 was not phosphorylated by the same enzyme, indicating the importance of that basic residue as the recognition site for protein kinase C.

Amino Acid Sequence↗
PubMed1987

Human bile duct carcinoma cell line producing abundant mucin in vitro.

A human bile duct carcinoma cell line, designated OZ, was established from ascitic effusion of a patient who suffered from obstructive jaundice due to the clogging of the common bile duct with mucinous substances secreted by the cancer cells. OZ was found to be capable of producing mucin in vitro and pools of mucin were macroscopically identified on the monolayer of the cells. On the electron micrographs, cell coat type mucin and abundant intracytoplasmic desmosomes were observed. The OZ cells secreted carcinoembryonic antigen in culture and had high enzymatic activity of gamma-glutamyl transpeptidase. The tumor heterotransplanted into nude mice also showed mucin production.

Adenocarcinoma, Papillary↗
PubMed1986

Lymphoid follicles appearing in gastric mucosa, especially in reactive lymphoid hyperplasia and malignant lymphoma.

Histopathological analysis of reactive lymphoid hyperplasia (RLH) and malignant lymphoma (ML) of the stomach was made based on the observations of lymphoid follicles appearing in gastric mucosa. The materials used for study consisted of 28 stomachs without RLH or tumor obtained from either operation or autopsy, 18 stomachs with RLH, and 46 stomachs with ML. Lymphoid follicles appeared soon after birth, increased with mucosal atrophy, and decreased in mucosa with intestinal metaplasia. They possessed a sinusoidal structure and appeared in the muscularis mucosae intimately related to the lymphatic flow. Excepting for the significant proliferative nature, the structural evolution of lymphoid follicles in RLH was similar to that in atrophic mucosa. They showed, however, a wide spectrum of changes containing cases with simple reactive changes to those with prelymphomatous changes. As to ML, the large cell type demonstrated a destructive proliferation, while both small and medium-sized cell types showed proliferation and infiltration preserving their original structure. In the superficial type, ML was frequently accompanied by RLH and mucosal atrophy. The histological features of ML consisted of not only the characteristics of tumor cells but also the proper mucosal changes including lymphoid follicles.

Adult↗
PubMed1985

Identification of the coding region for a second Epstein-Barr virus nuclear antigen (EBNA 2) by transfection of cloned DNA fragments.

Cell lines were established by co-transfection of cloned M-ABA Epstein-Barr virus (EBV) DNA fragments with plasmids conferring resistance to dominant selective markers. A baby hamster kidney cell line carrying the HindIII-I1 fragment exhibits a nuclear antigen of 82 000 daltons, serologically defined as EBV-determined nuclear antigen (EBNA) 1. Furthermore, a Rat-1 cell line transfected with DNA of the clone pM 780-28 containing three large internal repeats (BglII-U) and the adjacent BglII-C fragment expresses a nuclear antigen of 82 000 daltons which can be visualized only by a subset of anti EBNA-positive human sera. Sera recognizing the 82 000-dalton protein of the transfected cell line reacted with a protein of the same size in the non-producer line Raji, designated as EBNA 2. Conversely, sera without reactivity to the 82 000-dalton protein failed to react with EBNA 2 of Raji cells. P3HR-1 and Daudi cells with large deletions in BglII-U and -C are devoid of EBNA 2. The data presented provide evidence that a second EBNA protein is encoded by the region of the EBV genome which is deleted in the non-transforming P3HR-1 strain.

Antigens, Viral↗
PubMed1984

A complete set of overlapping cosmid clones of M-ABA virus derived from nasopharyngeal carcinoma and its similarity to other Epstein-Barr virus isolates.

DNA of the transforming, nondefective Epstein-Barr virus (EBV) strain M-ABA, which is derived from nasopharyngeal carcinoma cells, was cloned as large overlapping pieces into the cosmid pHC79 . The termini were cloned from closed circular virus DNA molecules out of M-ABA cell DNA in phage lambda L47 . The large overlapping clones were used to prepare a library of subclones with inserts of 1-15 kb. A detailed restriction enzyme map of M-ABA virus DNA reveals the close similarity to isolates from other sources. The high number of tandem repeats in EBV DNA stresses the importance of using cloning vectors that can be propagated in recA- Escherichia coli hosts.

Carcinoma↗
PubMed1984

Expression of a nuclear and a cytoplasmic Epstein-Barr virus early antigen after DNA transfer: cooperation of two distant parts of the genome for expression of the cytoplasmic antigen.

Expression of Epstein-Barr virus (EBV) antigens was studied after transfection of cloned EBV DNA fragments into baby hamster kidney (BHK) cells. A set of seven widely overlapping clones covering the whole genome of the non-defective Epstein-Barr virus strain M-ABA was used for transfection. Transfer of the cosmid clones into BHK cells resulted in expression of two distinct antigens, as revealed by indirect immunofluorescence using human anti-EBV sera. Staining with human sera of different reactivity against EBV-associated antigens revealed that both types of antigens were related to the early antigen complex. The first type of antigen was detected only in the nuclei of BHK cells that had received DNA of a clone containing HindIII-G, -H, -E, -I2, -O, -I1, and -P. The second type of antigen was found in the cytoplasm of cells cotransfected with clones containing Sal-A and HindIII-I2, -O, -I1, -P, and -C, whereas transfection of both individual clones failed to induce the antigen. Further analysis with subclones identified HindIII-G (5 kilobases) and HindIII-I2 (3 kilobases) plus the rightmost 3 kilobases of Sal-A as the sequences responsible for expression of the nuclear and the cytoplasmic antigen, respectively. The fact that two distant regions of the viral genome are required for expression of a viral antigen provides evidence for intergenomic regulation that can be studied in vitro.

Animals↗
PubMed1983

Nephrogenic adenoma in female urethra.

A case of a 66 years old female who had a nephrogenic adenoma recurring three times during a 6 months course of her illness is reported. With each recurrence, the lesion moved toward the urethral orifice, suggesting an intimate relationship between the recurrent process and physical stimuli to the mucosa. Electron microscopy revealed merely non-specific morphological features of epithelial cells in the lesion. There were no positive morphological clues in the lesion for supporting the lesion to resemble mesonephric and/or mesodermal tissue. The diagnostic term of tubular metaplasia for the lesion is preferable instead of nephrogenic adenoma.

Adenoma↗
PubMed1980

IgM antibodies to Epstein-Barr virus-associated membrane antigen in sera of infectious mononucleosis patients.

By the indirect immunofluorescence technique, IgM antibodies to the cell surface of an Epstein-Barr virus (EBV) producer cell line, P3HR-1, were detected in sera from infectious mononucleosis (IM) patients but not in sera from patients with Burkitt lymphoma or nasopharyngeal carcinoma nor in sera from healthy adult donors having antibodies to EBV-specific viral capsid antigen (VCA). Titers of the IgM antibodies were higher in the earlier stages of IM, a pattern similar to that for IgM antibodies to VCA. The IgM antibodies to the cell surface were identified as being those against the EBV-specific membrane antigen (MA) by the following criteria: (1) The antibodies were reactive to MA-positive cell preparations but to MA-negative cell preparations. (2) Titers of the IgM antibodies were not significantly affected after absorption of sera with sheep red blood cells which could completely eliminate heterophil antibodies in the same sera. Detection of the IgM antibodies to MA may have a particular diagnostic value for providing evidence of a recent EBV infection.

Antibodies, Viral↗
PubMed1980

Identification of target antigen for antibody-dependent cellular cytotoxicity on cells carrying Epstein-Barr virus genome.

The target antigen for antibody-dependent-cellular cytotoxicity (ADCC) on Epstein-Barr virus-(EBV) carrying lymphoblastoid cells expressing EBV-specific membrane antigen (MA) were examined with human serum antibody and adult human peripheral lymphocytes as effector cells. These studies confirmed that anti-MA-positive but not MA-negative sera were reactive in the ADCC. The ADCC reaction was positive with cells in which the MA consisted of late (LMA) and early (EMA) components. These included 1) MA-positive cells prepared by EBV antigen-adsorption, 2) cells carrying de novo-synthesized MA without adsorbed MA, and 3) EBV-producer cells expressing MA spontaneously. In all these preparations, the target cells were lysed roughly in parallel with the frequency of MA-positive cells. Inhibition of LMA synthesis in EBV-superinfected cells by phosphonoacetate (PA) reduced ADCC sensitivity significantly and to a far greater extent than MA synthesis as measured by immunofluorescence. This suggests that a target for ADCC is the PA-sensitive LMA. No ADCC reaction occurred with the cell preparation comprised of a high percentage of MA-positive cells induced by 5-iodo-2'-deoxyuridine, which is believed to be EMA only. These results strongly suggest that the target antigen for ADCC in EBV-positive cells is a late MA but not early MA.

Adsorption↗
PubMed1980

Hepatic fibrosis. The relation between proliferating bile ductules and alpha1-antitrypsin.

Since there is a remarkable increase in connective tissue around the proliferating bile ductules in chronic hepatitis and liver cirrhosis, the participation of proliferating bile ductules in hepatic fibrosis has been discussed by many during the past. With the use of immunofluorescent method, the present authors have recently succeeded in detecting alpha1-antitrypsin, a protease inhibitor, in the epithelial cells of proliferating bile ductules and a portion of the hepatocytes connected with these epithelial cells. When considering the posibility of alpha1-antitrypsin being secreted into the interstitial tissue, it is conceivable that this glycoprotein plays an important role in restraining collagenase activity, which takes part in the degradation of collagen, and leads to abnormal proliferation of collagen.

Bile Canaliculi↗
PubMed1976

Enzyme histochemical study on fat-storing cells (so-called Ito's cell) of liver.

Inorder to gain a foothold in clarifying the functional significance of fatstoring cells, an enzyme histochemical study on these cells was carried out. Fat-storing cells showed no alkaline phosphatase, acid phosphatase or esterase activity but demonstrated a marked gamma-glutamyl transpeptidase activity suggesting the possibility of its participation in the synthesis of fiber protein. This possibility was further heightened by its remarkable activity noted at the site of progressive fibrosis. Fat-storing cells under a normal condition partake in the formation of fibers supporting the sinusoidal wall, and under an abnormal condition gradually change their shape with loss of fat droplets and then transform into fibroblast-like cells closely related to the progress of fibrosis.

Fibroblasts↗