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Biomedical subjects

H Sasai

Publications and source records attributed to H Sasai.

At least 37 records · Page 2Linked to original sources
PubMed1993

Syrian hamster embryo cell lines useful for detecting transforming genes in mouse tumours: detection of transforming genes in X-ray-related mouse tumours.

The Syrian hamster embryo cell lines, SHOK and MC-1, were used as recipient cells for DNA transfection assay to detect transforming genes in experimental mouse tumours. A mouse repeat sequence was utilised to check whether each transformed focus included mouse genomic DNA in the Hamster background. We investigated five mouse tumours that are related to X-ray radiation, and detected activated c-K-ras, c-mos, and c-cot oncogenes which induced foci of hamster cells. These results show that SHOK and MC-1 cells have unique properties for detecting transforming genes in experimental mouse tumours.

3T3 Cells↗
PubMed1992

Oncogenic activation of murine mos protein kinase by DNA rearrangement of its N-terminal coding region.

An activated c-mos oncogene was detected by DNA transfection assay of hamster SHOK cells with DNAs from X-ray-induced mouse osteosarcoma. It was molecularly cloned by the cosmid rescue method and found to form transformed foci of SHOK cells. Genomic DNA sequencing revealed that in this oncogene the N-terminal coding region of the mouse proto-mos gene was deleted and replaced by a hamster-derived sequence in the primary transformant, suggesting that activation was due to the rearrangement during transfection. The gene product was about 37 kDa and was immunoprecipitated with anti-mos antibody from a lysate of a SHOK cell transfectant. This truncated mos (t-mos) gene transformed SHOK cells more effectively than v-mos. A chimeric gene construct of this hamster-derived upstream sequence and normal mouse c-mos also transformed SHOK cells at a lower level, whereas neither t-mos nor the chimeric c-mos gene transformed NIH3T3 cells appreciably. The high transforming efficiency of t-mos in SHOK cells was due not only to truncation of the coding region but also to its integration under a putative promoter sequence derived from the hamster genome. This is the first report of detection of an activated c-mos gene by DNA transfection assay.

Amino Acid Sequence↗
PubMed1990

Alteration of N-ras gene mutation after relapse in acute lymphoblastic leukemia.

We investigated N-ras activation in childhood acute lymphoblastic leukemia (dALL) by the polymerase chain reaction (PCR) and the oligonucleotide hybridization method. The frequency of point-mutation of the N-ras gene was not high (2 of 15), and one positive case who relapsed was analyzed in detail. Although N-ras gene activation was detected at both onset and relapse, the mutation sites were different. At onset, Gly (GGT) was changed to Ser (AGT) at codon 12, and at relapse, Gly (GGT) to Asp (GAT) was observed at the same codon. In addition, the DNA at relapse showed a remarkably higher transforming activity than the DNA at onset on two independent recipient cell lines. The identical cell surface phenotype and the same rearrangement patterns of both the immunoglobulin (Ig) heavy chain and T-cell receptor (TCR) gamma chain genes indicated that the leukemic cells at onset and those at relapse were derived from the same precursor cell. Therefore, this case supports the concept that ras activation is not the event initiating leukemogenesis, but may be involved in leukemic progression.

Base Sequence↗
PubMed1990

Hamster cell line suitable for transfection assay of transforming genes.

We established a subclone, SHOK, from the GHE-L cell line, an immortal line derived from a primary culture of Syrian hamster embryo cells, as a recipient cell line useful for the detection of oncogenes by transfection. SHOK cells were almost as susceptible as NIH 3T3 cells to focus formation by many oncogenes, including v-raf, v-Ha-ras, v-Ki-ras, or activated c-Ha-ras. The susceptibility of SHOK to focus formation was higher than that of NIH 3T3 for v-mos but was lower for v-fps, v-fgr, v-src, v-sis, and v-abl. When DNAs extracted from 27 human and murine tumors were tested for focus formation, 5 DNAs were positive in NIH 3T3 cells, whereas 9 were positive in SHOK cells at the primary transfection. Using SHOK cells as recipients of tumor cellular DNA, we isolated another oncogene and a c-Ki-ras2 gene mutated at codon 146 that were difficult to detect in NIH 3T3 cells. SHOK cells have a low rate of spontaneous transformation, produce easily distinguishable foci, and maintain a stable karyotype in transformed cells. In addition to being useful for the screening of human tumor DNAs, SHOK cells will be useful for the isolation of oncogenes from murine tumors because of their hamster origin.

Animals↗
PubMed1990

A clinicopathological study of so-called denture fibroma.

We investigated 60 cases of so-called denture fibroma, most of which occurred in women in their 50s to 70s. The most commonly affected areas were the upper alveolar ridge and the bottom of the alveolabial sulcus, and most of the prostheses responsible were complete dentures. Elevated and tumor-like lesions were most frequent. Histopathologically, about 60% of the lesions were of the fibromatous type. Degeneration and inflammation of the salivary glands were identified in one third of cases.

Adult↗
PubMed1990

[Study on occlusal sounds in children. (1). Influences of the velocity of tooth tapping on the occlusal sound].

The purpose of this study was to evaluate the influence of the maximum velocity of the mouth closing phase on the occlusal sound. Six subjects examined were divided into two groups (children and young adults). Occlusal sounds generated by the tooth tapping were obtained with in microelectronic condenser microphone placed on infra-orbital and external auditory canal. Three parameters were used for the measuring points such as 1) maximum velocity of the closing phase, 2) maximum amplitude of the occlusal sound, 3) duration of the occlusal sound. The results obtained in the present study were as follows: 1) The waveform of occlusal sounds obtained from infra-orbital showed more clearly than that obtained from the external auditory canal. 2) With increasing velocity, both the values of maximum amplitude and duration showed a tendency to increase in both groups. 3) The prolonging of the duration was apparent in the children. The results obtained in the study suggest that the analysis of the occlusal sounds generated by tooth tapping can apply to aid in the functional diagnosis of occlusion in children.

Adult↗
PubMed1990

[Study on occlusal sounds in children. 2. Fast Fourier Transform (FFT) analysis on the occlusal sounds].

The purpose of this study was to evaluate the Fast Fourie Transform (FFT) analysis of the occlusal sounds generated by tooth tapping which may apply in assisting in the functional diagnosis of occlusion in children. The fifteen subjects examined were divided into three groups: the first group with deciduous dentition, the second with mixed dentition and the third with permanent dentition. Occlusal sounds generated by tooth tapping at the rate of 76 times per minute were obtained with a micro-electronic condenser microphone placed on the infra-orbital region. For the time wave, the wave pattern of the occlusal sound was classified into two groups: 1) Impact sound, 2) Slide sound, and the ratio of appearance was examined. For the spectrum, three parameters were chosen for the measuring points such as 1) frequency range, 2) peak frequency, 3) strength of the peak frequency. The results obtained in the present study were summarized as follows: 1) Occlusal sounds in the deciduous dentition, the appearance of sliding sound was noticed in over 50% of the cases while on the permanent dentition, the sliding sound was dominant. 2) The power spectrum of the occlusal sound showed generally two or three peaks. 3) The range of frequency was recognized to be extended on the sliding sound when compared with the impact sound.

Child↗
PubMed1989

Cotransfection of plasmids with ras and myc oncogenes to diploid cells derived from rodent fetuses: alteration of neoplastic transformation frequency depending on the gestation period.

To analyze the mechanism of neoplastic transformation of rodent diploid cells by ras and myc oncogenes, human EJ c-Ha-ras and mouse c-myc second and third exons promoted by SV40 promoter were connected to pSV2neo and pSV2gpt, respectively. Mouse and rat primary fetal cells cotransfected with both genes formed transformed and nontransformed colonies in a medium containing G418 and mycophenolic acid (MPA). The proportion of transformed colonies in the total G418/MPA-resistant colonies decreased dependent on the stage of the gestation period of rat fetuses from which primary cells had been obtained. Analysis of randomly isolated colonies showed that the transformed colonies had a high copy number and high amount of expression of the introduced genes, were anchorage independent, and were tumorigenic in nude mice. On the other hand, the nontransformed colonies had a low copy number, low amount of expression, and no tumorigenicity. This contrast indicated not only that the activated Ha-ras and myc oncogenes had been integrated, but also that the amplification or overexpression (or both) of these genes was required for the rodent diploid cells to be transformed. We conclude that early-stage rat fetal cells might have endogenous factors that promote cell transformation. Alternatively, late-stage cells might have factors that suppress cell transformation by activated Ha-ras and myc oncogenes.

Animals↗
PubMed1989

Differential requirements of gag and gamma-actin domains for transforming potential of Gardner-Rasheed feline sarcoma virus.

The oncogene of Gardner-Rasheed feline sarcoma virus (GR-FeSV) encodes the 70-kilodalton protein containing gag(p15), gamma-actin, and fgr domains. To determine the role of these domains in the biological activity of P70gag-actin-fgr, we have constructed in-frame deletion and insertion mutants of GR-FeSV. We found, first, that the gamma-actin region could be deleted without affecting the transforming ability of these constructs, although an insertion mutant in the middle of the gamma-actin domain (map position 671) was partially defective in transformation and specifically had a reduced level of in vitro autophosphorylation activity. Second, mutations affecting the C-terminal third of the gag region appeared to abolish the ability to transform NIH 3T3 cells and autophosphorylation activity. These results suggest that the gamma-actin domain is not essentially required for the transforming activity of GR-FeSV but that it may take part in maintaining the conformational integrity of P70gag-actin-fgr and that the gag(p15) domain might have a critical role in modulating the function of P70gag-actin-fgr.

Actins↗
PubMed1988

A simple and useful method for simultaneous screening of elevated levels of expression of a variety of oncogenes in malignant cells.

Abnormal expression of various oncogenes has been implicated in the development of many malignant tumors. Although RNA blotting methods have been used to measure abnormal expression, they involve the time-consuming process of individually labeling the oncogene probes. To simplify this process we have attempted to develop a new method, termed simultaneous screening, which is based on the synthesis of radiolabeled cDNA corresponding to the mRNA population of malignant cells and on hybridization with various oncogene probes, immobilized on a membrane filter. This method circumvents the time-consuming process of the prevailing RNA blotting methods and is also sensitive enough to detect accurately a five- to ten-fold level of expression of rare mRNA (approximately 10 copies per cell). Overexpression of ten oncogenes was detected in a variety of malignant cells and mitogen-stimulated cells with this method. These results suggest that our simultaneous screening method can be used to examine the overexpression of oncogenes.

DNA↗
PubMed1988

Hexacosanoate contents in Japanese common foods.

Recently, a diet enriched in oleate and moderately restricted in hexacosanoate (C26:0) was found effective to reduce the plasma very long chain fatty acid (VLCFA) levels in patients with adrenoleukodystrophy (ALD), an X-linked disorder characterized by demyelination of the adrenal cortex and cerebral white matter, and accumulation of saturated VLCFA, particularly C26:0, in tissues of the demyelination. The information about the C26:0 content in Japanese food was, however, almost nil except for one report about foods in the USA, but this did not include some Japanese common foods. With the hope of treating an ALD patient in our hospital, C26:0 contents in Japanese common foods (42 items) were measured. In our case, a one-hour direct transesterification method was used to obtain methylesters of total fatty acids in foods and they were applied directly to a selected ion monitoring gas chromatography-mass spectrometry for the quantitative C26:0 analysis. The C26:0 content in nuts and seeds as well as in fats and oils was found to be significantly higher than in other foods; the content was highest in peanuts. The content in almost all kinds of examined fishes, the common protein foods in Japan, was relatively low. From these data and that in the national nutrition survey in 1986, the daily intake of C26:0 from the average Japanese diet could be estimated to be 12-36 mg. It can be recommended, therefore, that nuts and seeds as well as fats and oils should be restricted as severely as possible from the diet of ALD patients in Japan in order to keep daily C26:0 intake below 10 mg as recommended in the USA.

Adrenoleukodystrophy↗
PubMed1986

Uterine secretions induce phagocytosis of Escherichia coli by neutrophils.

Phagocytosis of Escherichia coli by neutrophils was induced in the presence of uterine secretions. The phagocytosis-inducing activity of uterine secretions was not changed by heat-treatment (56 degrees C for 30 min). The phagocytosis-inducing activity of uterine secretions from rabbits treated with estradiol-17 beta was slightly higher than that from control rabbits treated with vehicle. On the other hand, administration of progesterone significantly depressed phagocytosis-inducing activity of uterine secretions, and the inhibitory effect of progesterone was not affected by estradiol-17 beta. Neutrophils pretreated with uterine secretions did not phagocytize intact bacteria; in contrast, bacteria pretreated with uterine secretions were phagocytized by intact neutrophils. The present results suggest that there are heat-stable opsonins in uterine secretions which induce phagocytosis of bacteria by neutrophils, and that estrogen slightly enhances the opsonic activity of uterine secretions but progesterone depresses it and inhibits the promoting effect of estrogen.

Animals↗
PubMed1985

[Successful treatment of mediastinal seminoma with combination chemotherapy of cis-diamminedichloroplatinum (CDDP), vinblastine (VBL), and bleomycin (BLM)].

Complete response (CR) has been achieved in a case of advanced mediastinal seminoma using PVB therapy (CDDP, VBL, BLM). A 21-year-old man visited our department with the complaint of superior vena cava syndrome. Chest X-ray film, ultrasonography and CT scan revealed a large anterior mediastinal mass. Histological proof of mediastinal seminoma was obtained by needle biopsy. The patient was treated with a combination chemotherapy, consisting of CDDP, VBL and BLM according to Einhorn's PVB regimen. After three courses of this regimen, complete disappearance of the tumor was obtained. The patient underwent further radiation treatment (Linac: 4,000 rad), as a salvage therapy, at the anterior mediastinum, and has since been doing well without any sign of recurrence for a follow-up period of nine months.

Adult↗