Biomedical subjects

T Sado

Publications and source records attributed to T Sado.

At least 37 records · Page 2Linked to original sources

PubMed2000

[Reconstruction of chest wall using myocutaneous flap].

Reconstruction of chest wall using myocutaneous flap has been performed in 2 cases. A 72-year-old female referred to our hospital for locally recurrent left breast cancer without any distant metastases. The other patient was a 77-year-old female, having locally recurrent liposarcoma of the left lateral chest wall. Chest wall was resected with wide margin of normal tissue, and myocutaneous flaps of latissimus dorsi were used for reconstruction of skin defect (13 x 8 cm and 14 x 10 cm) in both cases. Although additional split-thickness skin graft was required for one of them, myocutaneous flaps were useful for the reconstruction of widely defected chest wall. By using this technique, wider margin can be obtained, which could decrease the risk for local recurrence of malignant tumor.

Aged↗

PubMed2000

[Clinical analysis of patients referred for lung transplantation in eastern Japan].

We investigated the indications for lung transplantation (LTx) in Japan and discussed questions regarding the current Japanese criteria of LTx. This study examined 37 patients referred to our institute for LTx. Among these patients, there were 11 cases of primary pulmonary hypertension (PPH), 6 of lymphoangiomyomatosis (LAM), 4 of Eisenmenger's syndrome, 3 of bronchiolitis obliterans, 2 each of bronchiectasis, idiopathic pulmonary fibrosis (IPF), and pneumoconiosis, and 7 of other diseases. The most frequent age group was 30-39 years (12 cases, 32.4%), and more than half of the patients were female (22 cases, 59.5%). The regions of residence of the patients were Tohoku (19 patients), Kanto (16), and Chubu (2). Patients were referred from all over eastern Japan. On evaluation, LTx was contraindicated in 5 cases, in 4 of which mechanical ventilation had been installed before consultation with us. Six patients died before registration on the Japan Organ Transplant Network (JOT). 6 transplant candidates were registered with JOT, but one (PPH) died after 6 months of waiting, and one (LAM) received a lung transplant from a brain dead cadaver donor. We propose to reform and clarify the Japanese criteria for LTx-both indications and contraindications, to include such indications as a survival probability of less than two years, and such contraindications as mechanical ventilation. Early consultation at LTx centers was hoped for, in accordance with the International Guidelines and a transplant window.

Adolescent↗

PubMed1999

Effect of CpG methylation on expression of the mouse imprinted gene Mest.

We previously reported isolation of the mouse gene, Mest (mesoderm-specific transcripts), which is mapped to the proximal part of chromosome 6 and predominantly expressed in the mesoderm and its derivatives during development. Peg1, a paternally expressed gene isolated by a systematic screening of imprinted genes, was recently demonstrated to be identical to Mest. We and others have shown that the human homolog (MEST) of Mest is also imprinted so as to be expressed from the paternal copy and maps to 7q32. To study transcriptional regulation of Mest/Peg1, we examined the effect of DNA methylation on its expression. In the embryonal carcinoma (EC) cell line, MC12, from which Mest was originally isolated, the 5'-region harboring presumptive promoter of the gene was undermethylated. On the other hand, C4XX, a subclone of MC12 which had lost expression of Mest, was characterized by extremely high levels of methylation in the 5'-region, demethylation of which resulted in activation of Mest. Furthermore, a methylated reporter construct with the luciferase gene under the control of the putative promoter region of Mest was not competent to produce luciferase activity in MC12 cells. These results suggest a suppressive role for DNA methylation in Mest expression. However, neither methylated nor unmethylated reporter constructs showed luciferase activity in a primary culture from the adult kidney, in which Mest is down-regulated despite apparent unmethylation of the paternal allele. Taken together, the data suggest that there are probably two modes of regulation for the Mest gene; one being a methylation-dependent mechanism that regulates imprinted expression of Mest during development, and the other being a methylation-independent mechanism that is involved in down-regulation of Mest in adult tissues.

Animals↗

PubMed1999

Calorie restriction and spontaneous hepatic tumors in C3H/He mice.

Caloric restriction started at the young adult (YA) stage and the full adult (FA) stage in mice was compared, specifically focussing on whether there would be a delay in the onset time of spontaneous hepatoma or a reduction in its frequency. Caloric restriction lengthened the life spans of both groups, the YA, and FA. Both groups showed striking reductions of spontaneous hepatomas, from 70.9 +/- 3.5% for non-restricted controls down to 35.7 +/- 5.7 and 30.4 +/- 4.0%, for mice restricted from young adult, and from full adult stages, respectively; further, the numbers of tumor-free mice in the restricted groups increased by 45.7% and 38.5%, respectively, from 11.5%, in the non-restricted control. The cumulative incidences of hepatoma in the caloric restricted groups showed a delayed and lower incidence compared with those of the non-restricted group; a parallel delay might result from a weakened activity in tumor-promotion, whereas a lower frequency, might reflect a possible reduction of target cells for hepatomata development. Both effects can be assumed to have resulted from caloric restriction. When cumulative incidences of small hepatomas were compared between the two restricted groups, restriction started at the young adult stage is assumed to have caused fewer initiation stresses, as well as to have delayed promotion, as clearly evidenced by a flatter curve of incidence with a lower total incidence. Thus, the time at which caloric restriction is started plays a critical role in its subsequent effects.

Aging↗

PubMed1999

Low frequency of Ras gene mutation in spontaneous and gamma-ray-induced thymic lymphomas of scid mice.

Scid mice, which have a defect in the capacity to repair DNA double-strand breaks, were highly prone to the induction of thymic lymphomas after exposure to ionizing radiation; approximately 70% of mice developed lymphomas within 1 year after exposure to 1-3 Gy, whereas approximately 20% of unirradiated control mice developed lymphomas. To gain information on the possible role of Ras activation in development of thymic lymphomas in scid mice, we have examined both the frequency and the spectrum of Kras and Nras mutations in spontaneous and radiation-induced lymphomas. Neither activated Kras nor Nras genes were detected in spontaneous lymphomas, while Kras mutations increased in a dose-dependent manner in radiation-induced lymphomas. However, Kras mutations were infrequent (6% in lymphomas in mice exposed to 1 Gy, 12.5% in those exposed to 2 Gy, 16.7% in those exposed to 3 Gy), and no mutations were detected in Nras genes, suggesting that Ras mutation was not significantly involved in the development of thymic lymphomas in scid mice. Analysis of the spectrum of Kras mutations demonstrated unique mutations in both codons 13 (GGC to GAC) and 61 (CAA to CTA) in addition to the commonly identified substitution of GAT for GGT in codon 12 of Kras.

Animals↗

PubMed1998

Possible induction of graft-versus-leukemia effect against a leukemia refractory to antileukemia response in ordinary MHC-compatible, allogeneic bone marrow transplantation.

We previously indicated that intensity of the graft-versus-leukemia (GVL) effect varied among different leukemias in MHC-compatible, allogeneic bone marrow transplantation (BMT). Cellular factors responsible for differences in intensity of the GVL effect were examined by using two types of leukemias, i.e., a resistant leukemia (LE750) and a sensitive leukemia (8313) to induction of the GVL effect in MHC-compatible, allogeneic BMT of leukemia-bearing host. Resistance of LE750 leukemic cells to induction of the GVL effect could not be attributed to either less sensitivity to lysis by minor H antigen-specific, cytotoxic T cells or to an immunosuppressive activity of LE750 leukemic cells in leukemia-bearing host, when compared with the case of the sensitive leukemia (8313). To investigate the significance of the dose effect of effector cells for induction of the GVL effect, we used CD8+ T cells of AKR donor mice, which were shown to preferentially induce the GVL effect with hardly any lethal graft-versus host disease against C3H recipient mice, enabling us to increase the number of CD8+ T cells used in the allogeneic donor inoculum. The results suggested that the outcome of the antileukemic response in allogeneic BMT of leukemic recipients may be determined, at least in part, by the balance between the size of leukemic cells surviving and repopulating in the recipients after BMT and the number of antileukemic effector cells. The results furthermore indicated that when donors with T-cell subsets that preferentially induce an antileukemic response with reduced graft-versus-host disease are available, a more effective antileukemic response is inducible even against advanced leukemias.

Animals↗

PubMed1998

The mouse Gtl2 gene is differentially expressed during embryonic development, encodes multiple alternatively spliced transcripts, and may act as an RNA.

We have isolated a novel mouse gene (Gtl2) from the site of a gene trap integration (Gtl2lacZ) that gave rise to developmentally regulated lacZ expression, and a dominant parental-origin-dependent phenotype. Heterozygous Gtl2lacZ mice that inherited the transgene from the father showed a proportionate dwarfism phenotype, whereas the penetrance and expressivity of the phenotype was strongly reduced in Gtl2lacZ mice that inherited the transgene from the mother. Gtl2 expression is highly similar to the beta-galactosidase staining pattern, and is down-regulated but not abolished in mice carrying the Gtl2lacZ insertion. In early postimplantation embryos, Gtl2 is expressed in the visceral yolk sac and embryonic ectoderm. During subsequent development and organogenesis, Gtl2 transcripts are abundant in the paraxial mesoderm closely correlated with myogenic differentiation, in parts of the central nervous system, and in the epithelial ducts of developing excretory organs. The Gtl2 gene gives rise to various differentially spliced transcripts, which contain multiple small open reading frames (ORF). However, none of the ATG codons of these ORFs is in the context of a strong Kozak consensus sequence for initiation of translation, suggesting that Gtl2 might function as an RNA. Nuclear Gtl2 RNA was detected in a temporally and spatially regulated manner, and partially processed Gtl2 transcripts were readily detected in Northern blot hybridizations of polyadenylated RNA, suggesting that primary Gtl2 transcripts are differently processed in various cell types during development. Gtl2 transcript levels are present in parthenogenic embryos but may be reduced, consistent with the pattern of inheritance of the Gtl2lacZ phenotype.

Alternative Splicing↗

PubMed1998

Epigenotype switching of imprintable loci in embryonic germ cells.

Expression of imprinted genes is dependent on their parental origin. This is reflected in the heritable differential methylation of parental alleles. The gametic imprints are however reversible as they do not endure for more than one generation. To investigate if the epigenetic changes in male and female germ line are similar or not, we derived embryonic germ (EG) cells from primordial germ cells (PGCs) of day 11.5 and 12.5 male and female embryos. The results demonstrate that they have an equivalent epigenotype. First, chimeras made with EG cells derived from both male and female embryos showed comparable fetal overgrowth and skeletal abnormalities, which are similar to but less severe than those induced by androgenetic embryonic stem (ES) cells. Thus, EG cells derived from female embryos resemble androgenetic ES cells more than parthenogenetic cells. Furthermore, the methylation status of both alleles of a number of loci in EG cells was similar to that of the paternal allele in normal somatic cells. Hence, both alleles of Igf2r region 2, Peg1/Mest, Peg3, Nnat were consistently unmethylated in EG cells as well as in the primary embryonic fibroblasts (PEFs) rescued from chimeras. More strikingly, both alleles of p57kip2 that were also unmethylated in EG cells, underwent de novo methylation in PEFs to resemble a paternal allele in somatic cells. The exceptions were the H19 and Igf2 genes that retained the methylation pattern in PEFs as seen in normal somatic tissues. These studies suggest that the initial epigenetic changes in germ cells of male and female embryos are similar.

Animals↗

PubMed1997

Calorie restriction reduces the incidence of myeloid leukemia induced by a single whole-body radiation in C3H/He mice.

Dietary restriction, especially caloric restriction, is a major modifier in experimental carcinogenesis and is known to decrease significantly the incidence of neoplasms. Gross and Dreyfuss [Gross, L. & Dreyfuss, Y. (1984) Proc. Natl. Acad. Sci. USA 81, 7596-7598; Gross, L. & Dreyfuss, Y. (1986) Proc. Natl. Acad. Sci. USA 83, 7928-7931] reported that a 36% restriction in caloric intake dramatically decreased the radiation-induced solid tumors and/or leukemias. Their protocol predominantly produced lymphatic neoplasms. It is of interest to observe the effect of caloric restriction on radiation-induced myeloid leukemia, because the disease was observed to have been increased in the survivors of the atomic bombs in Hiroshima and Nagasaki. The spontaneous incidence of myeloid leukemia in C3H/He male mice is 1%, and the incidence increased to 23.3% when 3 Gy of whole-body x-ray irradiation was given. However, the incidence of myeloid leukemia was found to be significantly decreased by caloric restriction; it was reduced to 7.9% and 10.7% when restriction was started before (6 weeks old) and after (10 weeks old) irradiation, respectively. In addition, the onset of the myeloid leukemia in both restricted groups was prolonged to a greater extent as compared with the control diet group. Caloric restriction demonstrated a significant prolongation of the life span in the groups on a restricted diet after having been exposed to irradiation, either before or after dietary restriction, in comparison with mice that were only irradiated.

Aging↗

PubMed1997

Increased sensitivity of scid heterozygous mice to ionizing radiation.

In the present study, acute effects of ionizing radiation on animal survival, bone marrow cells and fibroblast cell lines of scid homozygous, scid heterozygous and wild-type mice with the same C.B-17 genetic background were examined. The sensitivities to ultraviolet light (UV) and various chemicals, bleomycin, mitomycin C, N-methyl-N'-nitro-N-nitrosoguanidine, methyl methanosulphonate, 5-fluorouracil, 6-mercaptopurine, 4-nitroquinoline 1-oxide and potassium bromate) were also investigated. In addition, micronucleus testing of whole-body irradiated mice was performed. Scid heterozygous mice were found to be less sensitive than the homozygotes but more sensitive to ionizing radiation than wild-type mice, not only in vivo but also for bone marrow cells in vitro, suggesting partial dominance under both conditions. In contrast, there were no differences in sensitivity to UV light and various chemicals, as compared with wild-type and scid heterozygous cell lines, either in vitro or in the micronucleus test.

Animals↗

PubMed1997

Limiting dilution analysis of T-cell progenitors in the bone marrow of thymic lymphoma-susceptible B10 and -resistant C3H mice after fractionated whole-body X-irradiation.

Earlier studies from this laboratory using Thy 1 congenic B10 strain mice suggested that a depletion of T cell progenitors (pre T cells) in the bone marrow in addition to the destruction of the thymus after fractionated whole body X-irradiation (IR) are the two main critical factors that cause differentiation arrest of initially repopulating intrathymic radio-resistant T cell progenitors, which then lead to the appearance of preneoplastic, prelymphoma cells, and eventually to highly neoplastic thymic lymphomas under the influence of the thymic environment. In order to explore the significance of the depletion (or reduction) of T cell progenitors in the bone marrow during pathogenesis of radiation-induced thymic lymphomas, we compared the pool size of pre T cells in the bone marrow and the spleens as well as the profiles of the regenerating thymocyte populations between thymic lymphoma induction-susceptible B10 and -resistant C3H strain mice following irradiation. The results indicated that irradiation severely depleted the pre T cells in the bone marrow and the spleens of both lymphoma induction-susceptible and -resistant mice. They also showed that in C3H mice the differentiation and maturation of intrathymic T cell progenitors which initially repopulated the depleted thymus seemed to proceed normally in spite of the poor cellularity, while this process was greatly suppressed in B10 mice. These data indicate that a depletion of pre T cells in the bone marrow combined with atrophy of the thymus in the irradiated mice is necessary, but not sufficient for development of thymic lymphoma. Implication of these findings on the possible mechanism of radiation-induced thymic lymphomagenesis is discussed.

Animals↗

PubMed1997

Radiation-induced myeloid leukemia in mice under calorie restriction.

The host-defense mechanisms against cancers are known to be modulated by changing the environmental factor(s). The spontaneous incidence of myeloid leukemia is about 1% in C3H/He mice, and the incidence increases up to 23.3% when a single dose of radiation, 3 Gy X-ray, is exposed to a whole-body. Since calorie restriction was known to reduce the incidence of spontaneous tumors, a question as to whether such radiation induced-increase of myeloid leukemia would be also decreased by calorie restriction, was aimed to answer to elucidate possible mechanism of radiation-induced myeloid leukemia. By the calorie restriction, the incidence of myeloid leukemia was significantly decreased. In addition, the latent period of the myeloid leukemia in the groups for calorie restriction was significantly extended at a greater extent as compared with the control diet groups. Number of hemopoietic stem cells, the possible target cells for radiation-induced leukemias, in the groups for the calorie restriction demonstrated a significant decrease, especially in the spleen, as compared with that in the control, when the evaluation was made at the time of radiation exposure.

Animals↗

PubMed1996

Genomic imprinting and chromosomal localization of the human MEST gene.

We have isolated a human homologue (MEST) of the mouse mesoderm-specific transcript (Mest) gene that shares about 70% nucleotide sequence homology. Northern blot analysis showed that the MEST gene was expressed in all major fetal organs and tissues so far examined, i.e., amnion, brain, heart, lung, stomach, gut, adrenal, kidney, muscle, and liver, which does not contradict with mesoderm-specific expression. MEST was abundantly expressed in hydatidiform moles of androgenetic origin, whereas it was barely detectable in dermoid cysts of parthenogenetic origin. Thus, it seems likely that the MEST gene, mapped to 7q32 by fluorescence in situ hybridization, is maternally repressed as the mouse homologue.

Amino Acid Sequence↗

PubMed1996

Activation of the inactive X chromosome induced by cell fusion between a murine EC and female somatic cell accompanies reproducible changes in the methylation pattern of the Xist gene.

Mouse embryonal carcinoma (EC) cell lines are divided into two classes with or without the capability of reactivating the inactive X chromosome from a fusion partner of female lymphocyte. The 5' region of Xist was partially methylated in reactivating-competent EC cells but was fully methylated in reactivating-incompetent EC cells having a single X chromosome. Partial or heterogeneous methylation implies methylation of each CpG site in about half of the cell independently of methylation status of neighboring CpG sites. Fusion of the reactivating-competent EC cells with female lymphocytes induced not only de novo methylation in the 5' region of Xist allele on the hitherto inactivated X chromosome, but also demethylation of the same region of Xist on the other X chromosome from the female somatic cell. In contrast, no such changes occurred in hybrid cells involving reactivating-incompetent EC cells. Thus, partial methylation of the 5' region of Xist most probably maintained by low maintenance and high de novo methylation efficiency is correlated with reactivation potential of the EC cell. It is possible that this unique methylation pattern is implicated in random X inactivation in EC-hybrid cells in vitro and in epiblast cells in vivo.

Animals↗

PubMed1996

Mosaic methylation of Xist gene before chromosome inactivation in undifferentiated female mouse embryonic stem and embryonic germ cells.

Epigenetic modification is implicated in the choice of the X chromosome to be inactivated in the mouse. In order to gain more insight into the nature of such modification, we carried out a series of experiments using undifferentiated mouse cell lines as a model system. Not only the paternally derived X (XP) chromosome, but the maternally derived one (XM) was inactivated in the outer layer of the balloon-like cystic embryoid body probably corresponding to the yolk sac endoderm of the post-implantation embryo in which XP is preferentially inactivated. Hence, it is likely that the imprint responsible for the nonrandom XP inactivation in early mouse development has been erased or masked in female ES cells. CpG sites in the 5' region of the Xist gene were partially methylated in female ES and EG and parthenogenetic ES cell lines as in the female somatic cell in which the silent Xist allele on the active X is fully methylated, whereas the expressed allele on the inactive X is completely unmethylated. In the case of undifferentiated ES cells, however, methylation was not differential between two Xist alleles. This observation was supported by the demonstration that single-cell clones derived from female ES cell lines were not characterized by either allele specific Xist methylation or nonrandom X inactivation upon cell differentiation. Apparently these findings are at variance with the view that Xist expression and X inactivation are controlled by preemptive methylation in undifferentiated ES cells and probably in epiblast.

Alleles↗

PubMed1996

Cytogenetic analysis of thymocytes during early stages after irradiation in mice with different susceptibilities to radiation-induced lymphomagenesis.

To investigate the relationship between radiation-induced chromosomal instability and lymphomagenesis, the incidences of chromosome aberrations and of cells with abnormal chromosome complements in the thymuses of B10. Thy 1.1 and STS/A strains which have shown marked differences in susceptibility to radiation-induced lymphomagenesis were compared at an early time (12-33 days) after whole-body X-irradiation (1.61 Gy X 4). Numerical and structural aberrations of chromosome in B10. Thy 1.1 mice were higher than those in STS/A mice. The average incidence of trisomy 15 was 37.5% (12/32 mice) from 12 days to 32 days after irradiation in B10. Thy 1.1 mice, whereas none was found (0/38 mice) in STS/A mice. Frequencies of aberrations in chromosomes 11, 12, 15 of the thymocytes from irradiated B10. Thy 1.1 mice were higher than those from irradiated STS/A mice, and especially, the most frequent translocations occurred in the E-F regions of chromosome 12. using B10. Thy 1 congenic mice, we found that in many cases (8/13), the chromosome aberrations detected in the thymocytes from B10. Thy 1.1 mice at an early time after irradiation could also be observed in the donor-type (Thy 1.1) lymphomas developed from recipient mice 4-5 months after intrathymic injection, suggesting that these chromosome aberrations have some role in lymphomagenesis. The difference of chromosome instability detected at an early time after irradiation might be due to genetic background with regard to genomic instability induced by radiation.

Animals↗

PubMed1996

[Two cases of clear cell tumor of the lung].

We report two cases of benign clear cell tumor of the lung, which were found as well-circumscribed lesions on chest X-ray films without any symptoms, and removed surgically. Light microscopy showed proliferation of clear cells filled with glycogen in both cases. Immunohistochemical examination performed in a case suggested that the tumor cells might be associated to a derivation from neural and/or smooth muscle cells, because of positive staining for NSE and SMA. In another case, the tumor formed a necrotic cavity, which could be detected by the preoperative MRI examination. This report might introduce a note of caution for the pathologic and radiographic diversity of this disease.

Adult↗

PubMed1996

[Clinicopathologic assessment of primary thymic carcinoma based on eighteen cases].

In order to study clinicopathologic characteristics of thymic carcinomas, 18 patients with thymic carcinoma and 56 patients with invasive thymoma were reviewed. All of them were underwent thoracotomy. Both 5-year and 10-year survival rates were 44% in the thymic carcinoma patients, while 5-year survival and 10-year survival rates were respectively 62% and 52% in the invasive thymoma patients. The survival rate of the thymic carcinoma cases was significantly lower than that of invasive thymoma cases (p < 0.05). Both surgical technique and anticancer chemotherapy. However, have been improved in these years, such as artificial vessels for great veins, panpleuro-pneumonectomy, cisplatin and so on. Those new techniques have brought the significantly higher survival rate in recent 10 cases of thymic carcinoma patients. Three-year survival rate of 10 cases after 1990 was 80% and it was 13% in 8 cases before 1989 (p < 0.01). We conclude that surgical procedure are necessary for the treatment of thymic carcinoma patients, and both chemotherapy and radiotherapy should be combined with the surgical procedures to completely remove the tumors.

Adult↗