Biomedical subjects

T Tsukada

Publications and source records attributed to T Tsukada.

At least 109 records · Page 6Linked to original sources

PubMed1995

Vasoactive intestinal peptide gene expression in the rat pheochromocytoma cell line PC12.

Vasoactive intestinal peptide (VIP) gene expression was analyzed in PC12 cells. VIP mRNA was detected in PC12 cells treated with VIP or forskolin whereas no VIP mRNA was detected in the untreated cells. The induction of the VIP mRNA was enhanced by the simultaneous treatment with 12-O-tetradecanoylphorbol-13-acetate (TPA). PC12 cells stimulated with forskolin plus TPA released immunoreactive VIP. Sephadex G-50 column chromatography revealed that the immunoreactive VIP secreted from PC12 cells is comprised of multiple forms, one of which was indistinguishable from the authentic VIP. PC12 cells supported an efficient transcription from the human VIP gene promoter in a cell-specific as well as cAMP-dependent manner. These results definitely demonstrated the expression of the VIP gene in PC12 cells. VIP biosynthesis may be positively regulated by VIP in an autocrine fashion in PC12 cells.

Animals↗

PubMed1995

A mouse erythroleukemia cell line possessing friend spleen focus-forming virus gp55 transgene and temperature-sensitive mutant p53 gene.

Two different erythroleukemia cell lines have been established from the splenic lesions of transgenic mice possessing the Friend spleen focus-forming virus (F-SFFV) gp55 gene. One showed a near-diploid karyotype and a temperature-sensitive (ts) p53 mutation, and the other, a hyper-triploid karyotype with double p53 mutations found by single-strand conformation polymorphism (SSCP) analysis. The cell lines both retained No.11 chromosomes on which p53 genes are localized. Another p53 allele in the cell line with the ts-p53 mutation appeared intact in the SSCP analysis of the genomic exon 5. The cells with the ts-mutant p53 gene showed no apparent change with temperature shift in their growth or dimethylsulfoxide-induced differentiation, although the wild-type p53 gene on the other allele was not expressing. This ts-p53Val-135 gene made p53-deficient fibroblasts anchorage-independent at 37 degrees C but not at 32 degrees C. This non-virus-producing, mouse erythroleukemia cell line will be useful for the study of mutated p53 function during the induction of erythrodifferentiation or apoptotic change.

Animals↗

PubMed1995

A novel somatic point mutation of the RET Proto-oncogene in tumor tissues of small cell lung cancer patients.

We examined whether the novel point mutation from GCC (Ala) to GAC (Asp) at codon 664 in exon 11 of RET proto-oncogene, which we had found in two small cell lung carcinoma (SCLC) cell lines, existed in genomic DNA of tumor tissues of the two SCLC patients from whom these SCLC cell lines were derived. Sequence analysis revealed that point mutation identical to that of the SCLC cell lines was present in amplified alleles of single-strand conformational variants in genomic DNA of the tumor tissues, whereas it was not detected in genomic DNA of non-tumor tissues of the patients. These results indicate that this mutation had initially occurred in the SCLC patients and was of somatic origin.

ACTH Syndrome, Ectopic↗

PubMed1995

Reduction of serum cholesterol levels alters lesional composition of atherosclerotic plaques. Effect of pravastatin sodium on atherosclerosis in mature WHHL rabbits.

We examined whether serum cholesterol reduction alters the lesional composition of atherosclerotic plaques. To reduce serum cholesterol levels, we gave pravastatin sodium, a 3-hydroxy-3-methylglutaryl Coenzyme A reductase inhibitor, to mature Watanabe heritable hyperlipidemic rabbits, an LDL receptor-deficient animal model, for 48 weeks. Atherosclerotic lesions were immunohistochemically and conventionally stained and each lesional component area was measured by a color image analyzer. Compared with those of a placebo group, serum LDL cholesterol levels were reduced by 22% (P<.05). Data for atherosclerosis indicated a significant decrease in percent of surface lesion area (26% reduction) and in intimal thickening (30% reduction) in the abdominal aorta, as well as in coronary stenosis (29% reduction). Data for lesional composition indicated a significant decrease in the percent area of macrophage plus extracellular lipid deposits in aortic lesions (32% reduction) and coronary lesions (45% reduction). A significant increase was observed in the percent area of collagen in aortic lesions and in the percent area of smooth muscle cells in coronary lesions. The plaques seemed to become stable lesions as a result of pravastatin treatment. In conclusion, a long-term reduction of serum LDL cholesterol reduced lipid-related lesional components, in addition to suppressing the progression of established atherosclerosis.

Animals↗

PubMed1995

FK506 augments activation-induced programmed cell death of T lymphocytes in vivo.

FK506 is an immunosuppressive drug that inhibits T cell receptor-mediated signal transduction. This drug can induce immunological tolerance in allograft recipients. In this study, we investigated the in vivo effects of FK506 on T cell receptor-mediated apoptosis induction. Injection of anti-CD3 antibody (Ab) in mice resulted in the elimination of CD4+ CD8+ thymocytes by DNA fragmentation. FK506 treatment significantly augmented thymic apoptosis induced by in vivo anti-CD3 Ab administration. Increased thymic apoptosis resulted in the disappearance of CD4+ CD8+ thymocytes after anti-CD3 Ab/FK506 treatment. DNA fragmentation triggered by FK506 was induced exclusively in antigen-stimulated T cells, since enhanced DNA fragmentation induced by in vivo staphylococcal enterotoxin B (SEB) injection was confirmed in SEB-reactive V beta 8+ thymocytes but not in SEB-nonreactive V beta 6+ thymocytes. In addition to thymocytes, mature peripheral T cells also die by activation-induced programmed cell death. A similar effect of FK506 on activation-induced programmed cell death was observed in SEB-activated peripheral spleen T cells. In contrast, cyclosporin A treatment did not enhance activation-induced programmed cell death of thymocytes and peripheral T cells. Apoptosis is required for the generation and maintenance of self-tolerance in the immune system. Our findings suggest that FK506-triggered apoptosis after elimination of antigen-activated T cells may represent a potential mechanism of the immunological tolerance achieved by FK506 treatment.

Animals↗

PubMed1995

[A male case of primary Sjögren's syndrome with interstitial pneumonitis and interstitial tubulo-nephritis in the absence of dry eye and dry mouth: parotid gland MRI is a useful diagnostic method for Sjögren's syndrome].

Here we report a case of primary Sjögren's syndrome with hilar lymphadenopathy, interstitial pneumonitis and interstitial tubulo-nephritis. A 60-year old man was admitted to our hospital in May 1993 because of general fatigue and fever. He was noted to have hypergammaglobulinemia and had positive antibodies to nuclear antigens since 1990 in the absence of clinical manifestations. Since 9 months before admission, he presented with general fatigue, low grade fever and uveitis. On admission, chest X-ray and CT scan showed bilateral hilar lymphadenopathy and interstitial pneumonitis. The negative results for both serum angiotensin converting enzyme and histological findings of the cervical lymph node and the lung excluded the diagnosis of sarcoidosis. Serological examination exhibited marked elevation of polyclonal IgG level and anti-nuclear antibody, but neither anti-SS-A (Ro) nor anti-SS-B (La) antibody was detected. He did not have symptoms of xerophthalmia and xerostomia. Keratoconjunctivitis sicca was diagnosed by positive Schirmer's and rose bengal tests. His labial gland biopsy demonstrated severe mononuclear cell infiltration around the ducts. MRI findings of the parotid glands revealed heterogeneous and dotted high signal intensity similar to those in fat tissues in the T1- and T2-weighted images. These findings depicted that bilateral parotid gland was extensively destructed and was replaced by lipid tissue. Renal biopsy showed interstitial tubulo-nephritis. On the basis of the above findings, he was diagnosed to have primary Sjögren's syndrome and uveitis. Therefore, MR image of the parotid gland is considered to be a noninvasive and useful method for diagnosis of Sjögren's syndrome.

Humans↗

PubMed1995

[A case of adrenal angiosarcoma].

A 62-year-old male with slight fever, anorexia and easy fatigability was found to have a tumor in the left adrenal gland by computed tomogram of abdomen. Further study of angiogram suggesting neoplasm of the left adrenal gland, eventually he was underwent surgical extirpation. Histological study, combined with immunohistochemical staining, revealed that the tumor measuring 8 x 4 x 6 cm was an angiosarcoma. The patient died of pulmonary dysfunction 42 days after the operation. Autopsy was not done. In the literature, 7 cases of adrenal angiosarcoma have been reported; ours is the 8th case.

Adrenal Gland Neoplasms↗

PubMed1995

[Clinical significance of platelet volume indices estimated by automated blood cell analyzer].

Clinical significance of platelet volume indices (Platelet distribution width: PDW, Mean platelet volume: MPV, Platelet large cell ratio: P-LCR) estimated by automated blood cell analyzer (Sysmex NE-8000) was studied in 29 ITP cases and 17 cases with platelet hypoproduction which diagnosis was established by platelet kinetic study, megakaryocyte counts and the amount of platelet-associated IgG. These indices were not obtained by analyzer in 48% of 23 cases with platelet count less than 50 x 10(9)/l and 23% of 31 cases with platelet counts ranged in 50-100 x 10(9)/l. The coefficient of variation (CV) of PDW, MPV and P-LCR estimated 5 times in samples with platelet count more than 100 x 10(9)/l was 2%, 1% and 2.3%, respectively. In samples with platelet count less than 50 x 10(9)/l, CV of each index increased 3 times or more. Only four out of 22 ITP cases with platelet count less than 100 x 10(9)/l showed increased platelet volume and remaining 18 cases showed normal volume. In 12 cases with platelet hypoproduction, 3 cases showed increase of platelet volume and one case showed decrease of volume. Significant correlation was observed in between PDW and platelet survival time (r = -0.41, p < 0.05) and in between PDW and platelet turnover rate (r = 0.38, p < 0.05) in 29 ITP cases. Although the various changes of platelet volume indices during recovery phase after chemotherapy were observed in cases of acute leukemia or malignant lymphoma, these one were not a characteristic change in recovery phase of platelet under-production but rather different in each individual.

Blood Platelets↗

PubMed1995

FUS/TLS-CHOP chimeric transcripts in liposarcoma tissues.

Myxoid liposarcoma and malignant fibrous histiocytoma (MFH) are common soft tissue sarcomas of adulthood. Histopathologically they often show intratumor heterogeneity. In some cases, differential diagnosis of liposarcoma and MFH is difficult. It has been reported that myxoid liposarcomas are characterized by chromosomal translocation t (12; 16) (q13; p11), and that this results in two types (type I and type II) of FUS/TLS-CHOP fusion transcripts. In this study, the FUS/TLS-CHOP chimeric transcripts in seven malignant soft tissue tumors of Asian patients were analyzed by reverse transcription-polymerase chain reaction, DNA blot hybridization and nucleotide sequencing. One myxoid liposarcoma and two round cell liposarcomas possessed a chimeric transcript whose fusion point was the same as that of the type I fusion transcript reported previously for myxoid liposarcoma. We were thus able to detect the type I FUS/TLS-CHOP fusion transcript in clinical specimens of liposarcoma from Asian patients, including the first examples of round cell liposarcoma. These results suggest that the detection of FUS/TLS-CHOP chimeric transcripts or chimeric genes can be used as a diagnostic tool for the pathological diagnosis of liposarcomas.

Adult↗

PubMed1994

Prevention of anti-CD3 monoclonal antibody-induced thymic apoptosis by protein tyrosine kinase inhibitors.

The thymus gland is crucial for the formation of thymocytes of diverse TCR specificity. Recent studies have demonstrated that deletion (negative selection) of autoreactive thymocytes occurs through the process of apoptosis in which TCR activates cell death by DNA fragmentation. In addition, in vitro stimulation of thymocytes with anti-CD3 mAb, calcium ionophore, or glucocorticoids results in DNA fragmentation followed by cell death. The availability of various substances capable of inhibiting activation-induced programmed cell death of thymocytes may be used as a tool to help identify several important events occurring during the process of apoptosis. We investigated the effect of protein tyrosine kinase (PTK) inhibitors, herbimycin A and genistein, on thymocyte apoptosis induced by stimulation of anti-CD3 mAb or glucocorticoid. Anti-CD3 mAb stimulation resulted in removal of CD4+CD8+ thymocytes by DNA fragmentation. However, in PTK inhibitor-pretreated thymocytes, there was a minimal deletion of double positive thymocytes. In contrast, PTK inhibitors did not prevent glucocorticoid-induced thymic apoptosis. Our results suggest that anti-CD3 mAb-induced thymic apoptosis depends on PTK activation via TCR, and that glucocorticoid-induced thymic apoptosis is PTK-independent.

Animals↗

PubMed1994

Mutations in ras genes in cells cultured from mouse skin tumors induced by ultraviolet irradiation.

Mutations in ras oncogenes were detected in cultured cells of mouse skin tumors induced by near-UV irradiation. DNA extracted from the UV-induced tumor cells was transfected to golden hamster embryo cells, and focus-forming ability was confirmed in 22 of 26 cell strains, 15 of which had the repetitive mouse sequence. Mouse ras genes were detected in 10 of these 22 cell strains. Point mutations in the ras genes were at Ha-ras codon 13 (GGC-->GTC in two strains, GGC-->AGC in one strain), Ki-ras codon 61 (CAA-->GAA in two strains), and N-ras codon 61 (CAA-->CAT in two strains, CAA-->AAA in two strains). In one tumor cell strain no base change was directed. Most mutations occurred at dipyrimidine sites. Pyrimidine dimers or pyrimidine(6-4)pyrimidone photoproducts are the likely cause of the skin cancers. The base change occurred preferentially at G.C base pairs, and transversions predominated.

Animals↗

PubMed1994

Remarkable activation of polyamine biosynthesis in hematopoiesis and hyperplasia of spleen in mice with hemolytic anemia caused by infection with Plasmodium berghei.

Ornithine decarboxylase (ODC) activity was markedly induced in the spleen of mice infected with Plasmodium berghei, showing maximal activity at 8 days after the infection. The increase of spleen weight, on the other hand, reached its peak after 14 days of infection. In the blood of P. berghei-infected mice, no increase of ODC activity was observed. This indicated that ODC was induced in the spleen cells, but not in the parasites themselves which existed in the blood. Polyamines (putrescine, spermadine and spermine) were also elevated in the spleen following induction of the ODC activity. On the other hand, increases of ODC activity and spleen weight were observed in the spleen of mice with hemolytic anemia induced by acetylphenylhydrazine, but the extent of these increases were smaller than those in the spleen of mice infected with P. berghei. The present results suggest that increases in ODC activity and polyamine levels in the spleen of P. berghei-infected mice are related to hyperplasia of the spleen (splenomegaly) where the formation of leukocytes and erythrocytes (hematopoiesis) was dramatically stimulated by the infection.

Anemia, Hemolytic↗

PubMed1994

Functional analysis of the cell-specific enhancer in the human proopiomelanocortin gene by beta-galactosidase histochemical staining.

Nucleotide sequences responsible for the cell-specific expression of the human proopiomelanocortin (POMC) gene were analyzed by histochemical staining of beta-galactosidase in culture cells transfected with chimeric genes containing the 5'-flanking regions of the human POMC gene fused to the Escherichia coli lacZ gene. The chimeric genes were stably introduced into various culture cells, including AtT-20 cells, which express the endogenous mouse POMC gene. Whereas the control gene containing the cytomegalovirus enhancer was expressed in all cell lines tested, only AtT-20 cells supported the efficient transcription of the gene containing 2.9 kb of the human POMC 5'-flanking region. These results indicate that the stable transfection-expression system utilizing the histochemical detection of the gene expression is a useful method for the analysis of cell-specific gene expression. These results have also confirmed that the trans-acting factors in mouse AtT-20 cells interact with the human POMC gene promoter region and activate the transcription of the gene. Deletion analysis has demonstrated that the profiles of the transcriptional activity of the various human POMC-lacZ fusion genes are similar to those of the rat POMC gene described previously. Comparison of the human and the rat 5'-flanking sequences revealed close homology in several regions, which might be involved in the efficient transcription of the POMC gene in AtT-20 cells.

Animals↗

PubMed1994

Cell compositions of coronary and aortic atherosclerotic lesions in WHHL rabbits differ. An immunohistochemical study.

This study investigated whether coronary atherosclerosis was different from aortic atherosclerosis in Watanabe heritable hyperlipidemic rabbits. Atherosclerotic lesions were immunohistochemically stained by using a monoclonal antibody for rabbit macrophages (RAM-11) and a monoclonal antibody for muscle actin (HHF35) and were also subjected to conventional staining. The areas of the major lesional components, ie, macrophages, smooth muscle cells, collagen fibers, and extracellular lipid deposits, were measured with a color image analyzer. The percent macrophage area in coronary lesions was significantly lower compared with aortic lesions at all stages (early fatty streak, transitional, and advanced), while the percent smooth muscle cell area and collagen area were significantly higher in early fatty streak lesions of the coronary arteries. In addition, the macrophage area/smooth muscle cell area ratio was significantly lower in coronary lesions compared with aortic lesions at all stages. In conclusion, coronary atherosclerosis had a small number of macrophages and was rich in smooth muscle cells, whereas aortic atherosclerosis showed the opposite features. These results suggested that the role of macrophages and smooth muscle cells in the initiation and/or progression of coronary atherosclerosis differs from the role of these cells in aortic atherosclerosis.

Aging↗

PubMed1994

An androgen receptor mutation causing androgen resistance in undervirilized male syndrome.

The molecular basis of androgen resistance was investigated in a patient with undervirilized male syndrome. Binding studies of the androgen receptors in the patient's genital skin fibroblasts revealed a normal binding capacity of 5 alpha-dihydrotestosterone, although the affinity to androgen was slightly lower than the normal control value. The androgen binding of the patient's receptor showed a moderate thermal instability when the assay temperature was raised from 30 to 41 C. Nucleotide sequencing analysis of the androgen receptor gene revealed a single nucleotide substitution in exon F, resulting in an amino acid alteration from leucine (CTC) to phenylalanine (TTC) at position 789 within the steroid-binding domain of androgen receptor. When expressed in COS-7 cells, the mutant androgen receptor harboring phenylalanine at position 789 showed thermolabile androgen-binding properties similar to those observed in the patient's genital skin fibroblasts. Cotransfection experiments with an androgen-inducible reporter gene demonstrated a decreased transactivational capability of the mutant receptor. These results indicate that this point mutation modified the receptor function and caused androgen resistance in this patient. This mutation caused the mildest form of all androgen insensitivity syndromes ever examined for mutations in the androgen receptor gene.

Adult↗

PubMed1994

Long-term survival in a patient with malignant carcinoid treated with high-dose octreotide.

Octreotide acetate, a long-acting somatostatin analogue, is effective in controlling and markedly reducing the symptoms of carcinoid crisis. We report a patient with carcinoid syndrome with prolonged survival for 4.5 years with high dose octreotide therapy and survived for 7.5 years after the first flushing, in spite of episodes of severe carcinoid crisis. Dose escalation was required in order to control carcinoid symptoms, and the final dosage was 5,950 micrograms/day. Although administration of such a high dosage of octreotide has never been reported before, we found that octreotide could be used at this dosage safely without inducing serious side effects, and probably prolonged the patient's survival. Our experience with this case indicates that octreotide acetate is an effective drug in controlling carcinoid crisis and prolonging survival without serious side effects.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1994

Successful continuous treatment with all-trans retinoic acid for acute promyelocytic leukemia; secondary malignancy after the treatment of osteosarcoma.

We report a rare case of complete remission for 32 months with continuous treatment with all-trans retinoic acid (ATRA) alone in a patient with acute promyelocytic leukemia which developed as a second malignancy after the treatment of osteosarcoma after failure of conventional chemotherapy. The adverse effects of ATRA were apparently tolerable.

Adolescent↗

PubMed1994

Immunohistochemical and quantitative analysis of cellular and extracellular components of aortic atherosclerosis in WHHL rabbits.

To investigate changes in the major components of atherosclerotic lesions during the progression of this disease, we measured the lesional areas of macrophages, smooth muscle cells, collagen fibers, and extracellular lipid deposits in the aortas of WHHL rabbits. Aortic segments with lesions of various stages were stained for histological and immunohistochemical examination, and the area of each lesional component was measured by a color image analyzer. In the early fatty streaks observed in 3-month-old rabbits, macrophages were predominant in the intima and were also observed in the inner layer of the media. In the transitional lesions (fibro-fatty streaks) found in rabbits at 11 to 15 months of age, an increase in the lesional area of macrophages was prominent compared to other lesional components. Thus, macrophages may play an important role in the progression of aortic atherosclerosis at this stage. In advanced complicated lesions observed in rabbits at 20 to 24 months of age, the area of macrophages and smooth muscle cells did not increase, whereas the area of collagen fibers and extracellular lipid deposits increased. Therefore, both the disruption of foam cells and fibrosis may play an important role in the progression of atherosclerosis at this stage.

Animals↗