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Biomedical subjects

K Ohtake

Publications and source records attributed to K Ohtake.

At least 19 recordsLinked to original sources
PubMed1997

A monoclonal antibody modulates neutrophil adherence while enhancing cell motility.

A monoclonal antibody (MoAb) to human neutrophils, designated 3H9, was established by screening for the inhibition of neutrophil adherence to plastic plates containing a medium supplemented with fetal calf serum (FCS medium). The antigen recognized by 3H9 was shown to be present on human leukocytes and found at the highest levels on granulocytes. On Western blotting, 3H9 reacted with a molecule having a molecular weight of 80 kDa. When this MoAb was added at the same time as a neutrophil stimulant (fMLP), the inhibition of neutrophil adherence to plastic plates in the presence of FCS medium was observed after 60 min incubation. Furthermore, this MoAb enhanced not only fMLP-induced chemotaxis but random migration of neutrophils as well. The mechanisms of these phenomena are discussed.

Animals↗
PubMed1995

Frequent loss of heterozygosity on chromosome 4 in diethylnitrosamine-induced C3H/MSM mouse hepatocellular carcinomas in culture.

Genetic changes, in particular the loss of heterozygosity (LOH) and the presence of c-Ha-ras codon 61 point mutations, were investigated in diethylnitrosamine-induced hepatocellular carcinomas (HCCs) in C3H/MSM F1 mice. (MSM are wild mice.) LOH analysis of 48 primary tumors with microsatellite probes covering at least one proximal and one distal site of each autosome revealed no obvious positive results for LOH. Analysis of 23 cell lines established from seven of these HCCs, however, showed LOH on chromosome 4 in all (seven of seven), even in early passages (G2-G3). With regard to other chromosomes, LOH was observed only rarely on chromosomes 16 and 19. These allelotype features were maintained in later passages (G11-G14), with only a few additional occurrences of LOH appearing on chromosomes 1, 6, and 8. Extensive analyses with multiple microsatellite probes from chromosome 4 and with 52 cell lines established from 24 HCCs of 18 mice revealed LOH in 22 of the tumors (92%), with the shortest region about 10 cM distal to the alpha-interferon gene. No c-Ha-ras oncogene activation in codon 61 was observed. These data indicate that loss of tumor suppressor genes on chromosome 4 may play an important role in mouse hepatocarcinogenesis in progression in vivo or in immortalization in vitro or both.

Alleles↗
PubMed1994

Subcutaneous sarcomas of probable neuronal origin in a transgenic mouse strain containing an albumin promoter-fused simian virus 40 large T antigen gene.

Frequent development of subcutaneous neurogenic sarcomas was observed in a hepatocellular carcinoma-producing transgenic mouse strain harboring an albumin-promoted simian virus 40 (SV40) large T antigen gene. Found unexpectedly in 19 out of 306 mice (6.2%) by 6 months of age, all the sarcomas were similar and were characterized as neurogenic on the basis of histological features including Homer-Wright type rosette formation, the presence of dense core granules of 100-200 nm diameter under the electron microscope, expression of neuron specific enolase, S-100 protein, and catecholamines, and nerve cell-like differentiation in culture in response to But2cAMP. Immunohistochemical study revealed tiny clusters of SV40 T antigen-expressing cells with neurogenic character in normal-appearing adult mouse subcutis as candidate progenitors of the sarcomas. The tumor cells strongly expressed large T antigen but did not express albumin or albumin mRNA at the detection sensitivity used. Transient transfection assay (CAT assay), however, revealed the presence of transcriptional factor(s) acting on the albumin promoter in tumor cells. Thus, the present investigation suggested the presence of specifically differentiated neurogenic cells in the mouse subcutis with aberrant expression of the transgene.

Albumins↗
PubMed1993

Frequent c-Ki-ras oncogene activation in mucous cell hyperplasias of pancreas suffering from chronic inflammation.

In order to scrutinize the possible significance of (nonatypical) mucous cell hyperplasia of the pancreas to neoplasia, we analyzed these lesions in terms of c-Ki-ras activation, which is known to be very frequent in pancreatic carcinomas. A total of 16 such mucous cell hyperplasias were collected from 10 pancreases resected for chronic pancreatitis. Tiny tissue fragments were taken from hematoxylin-stained sections by microdissection, and DNA analysis was carried out by the polymerase chain reaction amplification and oligonucleotide hybridization methods. Activating mutations of c-Ki-ras oncogene at codon 12 were detected in 10 of the 16 lesions (62.5%), a high rate as seen in carcinomas. The results indicated a clonal origin of cells comprising the mucous cell hyperplasia suggesting a neoplastic and/or precancerous nature.

Adult↗
PubMed1993

Histologic study on the metastatic process in the experimental model of lymph node metastasis.

The process of lymph node metastasis was studied in an experimental model that was successfully established in our laboratory. The model O-1N carcinoma was transplanted to the buccal pouch of 60 hamsters, and seven or eight hamsters were killed every week from 1 to 8 weeks for histologic examination. At 3 weeks, neoplastic invasion of vascular spaces was demonstrated, and early stage lymph node metastases were seen in five of seven animals. At 5 weeks, lymph node metastases were more advanced, and lung metastasis occurred in one animal. At 8 weeks, lymph node metastases were seen in all eight animals and lung metastases were seen in two of them. Tumor cells initially seen as clusters in afferent lymphatic vessels and in the peripheral sinuses gradually spread to the medulla, replaced the entire lymph node, and extended into adjacent extranodal tissue. The process of metastasis closely resembled that seen in human oral carcinomas.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1993

Malignant transformation of a mouse liver epithelial cell line by transfection of an activated c-H-ras gene with a point mutation at codon 12.

In order to scrutinize the reason why in mouse liver system only activated H-ras gene with a point mutation at codon 61 but not codon 12 is frequently seen although the latter mutation is highly frequent in methylnitrosourea-induced rat mammary tumors, transforming activity of these two types of mutated H-ras gene was investigated utilizing an immortalized but not fully transformed mouse liver epithelial cell line MLE-10, established in our laboratory. MLE-10 cells were transfected with activated human c-H-ras gene having a point mutation at either codon 12 (PT24) or 61 (PSK2), together with PSV2neo, or with PSV2neo only. G418 resistant colonies, propagated separately, gave rise to 6, 3 and 6 lines respectively. All the PT24 and PSK2-transfected cell lines were growth capable in both soft agar and nude mouse subcutis, with similar growth rate and morphological features whereas none of the cell lines transfected with the PSV2neo only revealed such growth capability. The results thus revealed that c-H-ras with a mutation at codon 12 has oncogenic activity to the mouse hepatocyte, although after immortalization, at the degree similar to the same gene with a mutation at codon 61.

Animals↗
PubMed1993

Integrin VLA-5 negative primary plasma cell leukemia.

We present a case of primary plasma cell leukemia with Bence Jones proteinuria. After combination chemotherapy, leukemic cells and the urinary levels Bence Jones protein were decreased. Small lytic bone lesions were detected only in the skull. Typical plasma cells were rarely seen in peripheral blood on the hyperleukocytic phase, however they were increased in the advanced stages. The most important diagnostic sign was persistent expression of CD38 antigen on leukemic cells throughout the entire course of the illness and these leukemic cells expressed very late antigen-4 (VLA-4) but not VLA-5.

ADP-ribosyl Cyclase↗
PubMed1993

Hepatocyte growth factor transforms immortalized mouse liver epithelial cells.

Transforming activity of hepatocyte growth factor (HGF) was demonstrated utilizing immortalized but not fully transformed mouse hepatocytes (MLE-10). Rat HGF cDNA, expressed under the control of a cytomegalovirus promoter, was transfected together with the neomycin resistance gene (PSV2neo) into MLE-10 cells by the calcium phosphate method, and propagated G418-resistant colonies were harvested colony by colony. After checking for integration and expression of exogenous HGF, five cell lines (MLE-10-HGF-1-5) were established. Three cell lines transfected with the vector only (MLE-10-CMV-1-3) were also established in the same manner. All MLE-10-HGF cell lines grew much faster than the MLE-10-CMV and original MLE-10 cells in culture and produced large colonies in soft agar, which colony production was blocked by the addition of anti-HGF antibody to the agar. After addition of HGF, original and MLE-10-CMV lines produced colonies in soft agar. The high-HGF-production lines (MLE-10-HGF-4 and -5) also gave rise to tumors within 2 weeks when implanted into the nude mice subcutis. In contrast, all MLE-10-CMV and original MLE-10 cells were negative in these growth assays. A rough parallelism between the level of HGF expression and the growth rate in both soft agar and nude mice subcutis was evident among MLE-10-HGF cell lines. Those with higher HGF production tended to grow in a scattered fashion in culture. High-affinity HGF receptor, HGFR/met, was expressed in MLE-10 and all the derived cell lines. Since HGF and/or HGFR/met gene expression is seen in various tumors and the serum HGF level is elevated in patients with hepatic disease, the present results indicate a possible significance of HGF and its receptor system in carcinogenesis, most probably via autocrine and/or paracrine mechanisms.

Animals↗
PubMed1992

Clonal growth of hepatitis B virus-integrated hepatocytes in cirrhotic liver nodules.

A total of 83 cirrhotic nodules (pseudolobules) individually collected from 11 cirrhotic livers of hepatitis B virus carrier patient were analyzed for the frequency and mode of hepatitis B virus integration as well as histological features. Southern blot analysis disclosed discrete bands at higher molecular weight region in 26 of 83 nodules (31.3%), indicating a clonal growth of hepatocytes with viral integration. Considerable variation (0-75%) existed in the positive rates for discrete bands in nodules among livers. Molecular cloning revealed the sequence flanking an integrated viral sequence to be host DNA and thus confirmed true integration. Histological analysis, however, did not reveal any neoplastic-appearing foci of growth within nodules, despite the fact that the detection sensitivity would predict clones of more than 10(5) cells to give rise to clonal integration patterns on Southern blot analysis. The question of whether clonal expansion of hepatocytes reflects any viral integration-associated growth advantage and/or a preneoplastic condition awaits future studies.

Adult↗
PubMed1992

Alteration of rat liver proteoglycans during regeneration.

Sepharose CL-6B column chromatography of crude extracts from the slices of regenerating rat livers after partial hepatectomy and sham-operated controls labeled with [35S]sulfuric acid revealed an enhancement of [35S]sulfate incorporation into proteoglycan fractions during regeneration. The 35S-labeled proteoglycans contained heparan sulfate (more than 80% of the total) and chondroitin/dermatan sulfate. The 35S-incorporation into both glycosaminoglycans increased to maxima 3-5 days after partial hepatectomy and decreased thereafter toward the respective control levels. When [35S]sulfuric acid was replaced by [3H]glucosamine, similar results were obtained. These results suggest that the maximal stimulation of proteoglycan synthesis in regenerating rat liver follows the maximal mitosis of hepatic cells 1-2 days after partial hepatectomy. The 35S-labeled proteoglycans from regenerating liver 3 days after partial hepatectomy and control were analyzed further. They were similar in chromatographic behavior on a gel filtration or an anion-exchange column and in glycosaminoglycan composition. Their glycosaminoglycans were indistinguishable in electrophoretic mobility. However, these proteoglycans were slightly but significantly different in their affinity to octyl-Sepharose and in the molecular-weight distribution of their glycosaminoglycans.

Animals↗
PubMed1992

Frequent spontaneous sister chromatid exchange in hepatocytes of transgenic mice harboring the SV40-T antigen gene.

In order to shed light on the causal mechanisms of hepatocarcinogenesis in the transgenic mouse into which the albumin-promotor-regulated SV40-T antigen gene has been introduced (T+ mouse), and especially on the frequent chromosomal aberrations seen in cultured hepatocytes and hepatocellular neoplasms derived from such animals, the frequency of sister chromatid exchange (SCE) and karyotype abnormalities were investigated in a hepatocyte primary culture system. Cells were obtained through collagenase perfusion from T+ mice at 16-18 days of age, when no morphological changes are apparent, and from nontransgenic littermates, and cultured in the presence of bromodeoxyuridine. SCE was seen in transgenic hepatocytes twice as frequently as in their normal counterparts. No karyotype abnormalities in terms of numerical change or gross aberration were detected at this phase. The results thus suggest mutagenic properties for the T antigen, which may play an important role in hepatocarcinogenesis in this transgenic mouse.

Animals↗
PubMed1992

Concurrent changes in sinusoidal expression of laminin and affinity of hepatocytes to laminin during rat liver regeneration.

Distribution of fibronectin, laminin, and collagens type I, III, IV, and V in the lobular regions of regenerating rat liver was studied by indirect immunofluorescence. Little or no laminin was detected in sham-operated controls throughout the experimental period, while it was detected in sinusoids of regenerating liver as early as 6 h after partial hepatectomy (PH). After reaching a maximum at 24 h, it decreased and was barely detectable 6 days after PH. Changes in the other extracellular matrix (ECM) proteins were evident 3 days after PH, but not earlier than 24 h. Hepatocytes isolated from regenerating rat livers were tested in a short term assay for attachment to the substrates coated with the ECM proteins. The attachment of hepatocytes to laminin substrates increased 12 h after PH, reached a maximum at 24 h, and decreased to the control level 6 days after PH, while that of the control remained constant. The attachment to fibronectin substrates was not different between regenerating livers and controls at any time point. The attachment to collagen did not change earlier than 24 h after PH, but increased slightly 3 days after PH. Primary rat hepatocytes cultured on the substrates coated with the ECM proteins were determined for replicative DNA synthesis in response to epidermal growth factor. Both in normal liver and in regenerating liver 24 h after PH, laminin was one of the most effective substrates in supporting the responsiveness of hepatocytes to the growth stimulus. Taken together, these results suggest the importance of hepatocyte-laminin interaction during the early stage of liver regeneration possibly in growth stimulation of hepatocytes and/or maintenance of hepatocyte-specific functions.

Animals↗
PubMed1992

The role of radiotherapy in the management of salivary gland carcinomas.

A retrospective study was performed on 44 patients with carcinoma originating in the major and minor salivary glands to examine the effects of postoperative radiotherapy on locoregional and distant control and survival. 22 patients were treated by surgery alone and the 22 other patients were treated by a combination of surgery and postoperative irradiation. In the surgery group, local recurrence developed in all 8 patients with evidence of residual disease at the surgical margins, whereas local control was achieved in 7 of 15 patients with positive surgical margins in the combination group and the control rate was related to the amount of residual disease. Neck metastasis, which developed in 13 patients (30%), was not affected by the status of surgical margins or by the treatment modality. On the other hand, the incidence of distant metastasis seen in 19 patients (43%) was much higher in patients with positive surgical margins and the development of distant metastasis in these patients was not prevented by postoperative irradiation. The survival rates at 5, 10 and 15 years were 54, 48 and 41%, respectively, for the irradiated patients, whereas the values for the patients treated by surgery alone were 75, 70 and 70%, respectively. The results indicate that postoperative irradiation is effective in controlling local recurrence but not neck and distant metastases. Wide excision with sufficient surgical margins followed by postoperative radiotherapy and systemic chemotherapy are essential to obtain a better prognosis.

Adolescent↗
PubMed1992

[Prognostic significance of echogenic lesion within small hepatocellular carcinoma].

To evaluate prognostic significance of echogenic lesion within small hepatocellular carcinoma (SHCC, less than or equal to 2 cm in diameter), clinical and pathological findings of 32 cases with SHCC containing echogenic lesion (echogenic SHCC) were compared with those of 55 cases with non-echogenic SHCC. Compared with the non-echogenic SHCC group, the frequency of clinical stage I was significantly higher, and there were significantly more cases with solitary tumor relative to cases with multiple tumors in the echogenic SHCC group. Histologically, the incidence of the HCC composed of well-differentiated tumor cells corresponding to Edmondson's grade I was significantly higher in the echogenic SHCC group than in the non-echogenic SHCC group. Although HCCs tended to become progressively less differentiated with increasing tumor sizes in the both groups, the process of cellular change appeared to proceed more slowly in the echogenic SHCC group. Survival rate after tumor detection was 73% at three years, 56% at five years and 48% at seven years and nine years in the echogenic SHCC group, while it was 46% at three years, 42% at five years and 0% at seven years in the non-echogenic SHCC group. The present results showed that the presence of echogenic lesion within SHCC could be useful prognostic indicator.

Aged↗