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Biomedical subjects

N Yamauchi

Publications and source records attributed to N Yamauchi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Immunohistochemical analysis of endometrial adenocarcinoma for bcl-2 and p53 in relation to expression of sex steroid receptor and proliferative activity.

In order to clarify the factors that affect growth of endometrial carcinoma, immunohistochemical analyses of bcl-2, p53, sex steroid receptors, and Ki-67 were performed in 35 cases of endometrial carcinoma (32 endometrioid and three clear-cell carcinomas). Correlation of antigen expression with clinicopathological features was analyzed. Expression of bcl-2 was found in 58.8, 33.3, and 20.0% of grade 1 (G1), grade 2 (G2), and grade 3 (G3) endometrial carcinomas, respectively. Estrogen receptor (ER) was observed in 70.6, 22.2, and 0% of G1, G2, and G3 cases (p < 0.01), respectively. In contrast, expression of p53 was found in 5.8, 33.3, and 60.0% of G1, G2, and G3 cases, respectively. The labeling index of Ki-67 correlated with p53 overexpression (p < 0.01). Lymph node metastases were observed in 6.6 and 5.5% of ER- and PR (progesterone receptor)-positive carcinomas, whereas metastases were observed in 44.4 and 53.3% of ER- and PR-negative carcinomas, respectively (p < 0.05). Lymph node metastases were observed in 50.0% of p53-positive carcinomas, whereas metastases were observed in 22.2% of p53-negative carcinomas (p < 0.05). These results suggest that bcl-2 expression in endometrial carcinomas is regulated in a hormone-dependent manner. Expression of bcl-2 may occur more frequently in estrogen-related, low-grade endometrial carcinomas, whereas p53 overexpression is found more often in endometrial carcinomas in estrogen-unrelated, high-grade endometrial carcinomas with prominent proliferative activity and a high frequency of lymph node metastases.

Adenocarcinoma↗
PubMed1996

Endogenous tumor necrosis factor inhibits the cytotoxicity of exogenous tumor necrosis factor and adriamycin in pancreatic carcinoma cells.

Pancreatic carcinoma is one of the most devastating neoplasms with regard to its resistance to conventional therapy. In a previous report, we found that endogenous tumor necrosis factor (enTNF) exerts an intracellular protective effect against exogenous TNF- and Adriamycin (ADM)-induced cytotoxicity by scavenging oxygen free radicals (OFR) with induced manganous superoxide dismutase (MnSOD). We also know that glutathione S-transferase pi (GST-pi) and glutathione (GSH) also scavenge OFR. It remains unclear to what extent enTNF and MnSOD induced by enTNF regulate the sensitivity to ADM and exogenous TNF among different carcinoma cells. In this study, we examined the relationship between ADM and exogenous TNF sensitivity and en-TNF expression and MnSOD activity in four pancreatic carcinoma lines. We determined whether ADM and exogenous TNF sensitivity could be predicted by measuring enTNF expression and MnSOD activity in the carcinoma cells. The sensitivity to TNF and ADM varied with the cell lines, and TNF sensitivity correlated well with Adriamycin sensitivity. Moreover, enTNF expression and Mn-SOD activity correlated positively with resistance to ADM and exogenous TNF. When MIAPaCa-2 cells, which had the lowest enTNF expression and the highest sensitivity to exogenous TNF and ADM, were transfected with the nonsecretory-type human TNF gene (pTNF delta pro) to increase enTNF synthesis, their intracellular MnSOD activity and exogenous TNF and ADM resistance were increased. These findings suggest that MnSOD plays a critical role in scavenging OFR induced by ADM and exogenous TNF. enTNF is the most important factor that regulates the production of MnSOD. Therefore, it is plausible that inhibition of enTNF expression or MnSOD activity in pancreatic carcinoma would improve the efficacy of therapies for pancreatic carcinoma.

Doxorubicin↗
PubMed1996

Tumor necrosis factor and interferon-gamma augment anticolon antibody- dependent cellular cytotoxicity in ulcerative colitis.

The effect of tumor necrosis factor (TNF) and interferon (IFN)-gamma on antibody-dependent cellular cytotoxicity (ADCC) in patients with ulcerative colitis (UC) was investigated. ADCC activity was measured by the 51Cr release assay, using peripheral blood mononuclear cells of healthy subjects as effector cells and RPMI 4788 cells derived from human colon cancer as target cells. ADCC activity under sera from healty subjects remained low whether or not the effector cells were pretreated with TNF (100 U/ml, 16h). Under sera from UC patients, ADCC activity of 13.9%, compared to 9.6% when pretreatment was deleted. The effect of IFN pretreatment (100 U/ml, 16h) was also examined under sera from UC patients; in that experiment activity rose to 26.8%, in comparison to a 10.7% when IFN-gamma pretreatment was deleted. Finally, when the effector cells were pretreated with both TNF and IFN-gamma (100 U/ml of each, 16h) the ADCC activity under sera from UC patients was higher than when either TNF or IFN-gamma were used alone. These results suggest that TNF and IFN-gamma, by increasing ADCC activity in UC lesions, are involved in cell injury in the colonic epithelium. IFN-gamma appears to increase ADCC activity by increasing the number of high affinity monocyte Fc gamma RI receptors, while TNF increases ADCC activity by a different mechanism.

Adjuvants, Immunologic↗
PubMed1995

Reversal of tumor necrosis factor resistance in tumor cells by adriamycin via suppression of intracellular resistance factors.

Tumor necrosis factor (TNF) and various chemotherapeutic drugs show synergistic antitumor effects in vitro and in vivo, though the mechanism is not clear. Based on our previous finding that endogenous TNF (enTNF) acts as an intracellular resistance factor against exogenous TNF by scavenging oxygen free radicals (OFR) with induced manganous superoxide dismutase (MnSOD), we examined the suppression of these resistance factors by chemotherapeutic drugs and the resulting increase in TNF cytotoxicity. Pretreatment of HeLa cells, which produce an appreciable amount of enTNF and show apparent TNF resistance, with TNF followed by adriamycin (ADM) resulted in an additive effect, whereas pretreatment with ADM followed by TNF resulted in a synergistic effect. After treatment of HeLa cells with ADM, the expression of enTNF was remarkably suppressed and MnSOD activity was decreased by one-half. These results indicate that suppression of the intracellular resistance factors, i.e., enTNF and MnSOD, by ADM plays an important role in the mechanism of the synergistic antitumor effect of TNF in combination with ADM.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

DNA analysis in hereditary dentatorubral-pallidoluysian atrophy: correlation between CAG repeat length and phenotypic variation and the molecular basis of anticipation.

Hereditary dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disease with variable clinical phenotypes. Progressive ataxia, choreoathetosis, and dementia are the main clinical features of adult-onset cases, whereas the main feature in juvenile-onset DRPLA is progressive myoclonus epilepsy. Earlier onset is apparent in successive generations (anticipation). The molecular abnormality underlying DRPLA is an expanded, unstable CAG trinucleotide repeat on chromosome 12p. We analyzed 71 DNA samples obtained from 12 Japanese DRPLA pedigrees that included 38 affected individuals. Normal alleles had 7 to 23 repeats, DRPLA alleles 53 to 88 repeats. DRPLA alleles also were detected in five asymptomatic family members. Patients with juvenile onset had significantly larger repeats than did those with adult onset, and there was a significant negative correlation between CAG repeat length and age at onset. In 80% of the paternal transmissions, there was an increase of more than five repeats, whereas all the maternal transmissions showed either a decrease or an increase of fewer than five repeats. There was a significant correlation between father-child differences in repeat length and differences in age at onset. The analysis of CAG repeat length is a reliable diagnostic test for DRPLA and is of value for the presymptomatic detection of individuals at risk. The expansion of CAG repeats is important in phenotypic variation and anticipation. In addition, the sex of the transmitting parent has a significant effect on the molecular mechanism of anticipation.

Adolescent↗
PubMed1995

Physiological concentrations of retinoic acid suppress the osteoblastic differentiation of fetal rat calvaria cells in vitro.

The effects of retinoic acid (RA) on osteoblastic differentiation and activity were studied in fetal rat calvaria cells cultured for up to 24 days. Fetal bovine serum used for the experiments was treated with an anion-exchange resin to remove endogenous RA. The depletion of RA in the treated serum was confirmed by high-performance liquid chromatography and tritiated RA tracing. Under the culture conditions employed, the continuous presence of RA for 14 days at 10(-9) mol/l or higher decreased both alkaline phosphatase (ALP) activity on day 12 and the number of bone nodules on day 14 in a dose-dependent manner. Short-term (24 h) exposure to RA at 10(-8) mol/l, which is a physiological concentration, decreased and increased the levels of ALP and osteopontin mRNA on day 6, respectively. Retinoic acid at 10(-8) mol/l also increased the level of osteocalcin mRNA on day 12. However, these effects were not obvious at later stages (days 18 and 24). At a high concentration (10(-6) mol/l), RA increased the level of osteopontin mRNA on day 6 and decreased the levels of ALP and osteocalcin mRNA irrespective of culture period. These results suggest that, at physiological concentrations, RA suppresses the differentiation of osteoprogenitor cells and regulates osteoblastic functions.

Alkaline Phosphatase↗
PubMed1994

Beta 1-adrenergic mechanism is involved in stress-induced increase in arousal.

It has been shown that 1 h restraint shortens pentobarbital (PbNa)-induced sleeping time and that brain corticotropin-releasing hormone (CRH) is involved in the mechanism by which restraint shortens. PbNa-induced sleeping time. The present study was designed to further examine the mechanism of the antagonistic effect of 1 h restraint on PbNa in rats. Intracerebroventricular (i.c.v.) administration of propranolol and metoprolol, but not butoxamine reversed the shortening of PbNa-induced sleeping time by 1 h restraint. The i.c.v. administration of phentolamine blocked the shortening of PbNa-induced sleeping time by restraint, while the same dose of phentolamine prolonged the sleeping time in unrestrained rats. Atropine did not affect the PbNa-induced sleeping time in restrained rats. These results suggest that in addition to CRH, the brain beta 1-adrenergic system is involved in the restraint stress-induced increase in arousal.

Animals↗
PubMed1994

Thyroid hormone suppresses the differentiation of osteoprogenitor cells to osteoblasts, but enhances functional activities of mature osteoblasts in cultured rat calvaria cells.

The effects of thyroid hormone on osteoblastic differentiation and activity were studied in fetal rat calvaria (RC) cells cultured for up to 30 days in medium supplemented with thyroid hormone-depleted serum. In this condition, the cells proliferated and differentiated to form mineralized bone nodules (BN) and expressed osteoblastic markers such as alkaline phosphatase (ALP), osteocalcin (OCN), and osteopontin (OPN). The continuous presence of triiodothyronine (T3) at 10(-9)-10(-8) M in the medium inhibited the osteoblastic differentiation: 34% decrease in ALP activity on day 12 and 60% decrease in BN formation on day 15 at 10(-8) M. T3 at these doses had no effect on the DNA content of RC cells at confluence (day 6). Short-term (48-h) exposure of T3 at 10(-9) M or higher decreased ALP activity when RC cells were differentiating (days 7-11). However, when BN formation by the cells had already reached a plateau (day 28), the activity was increased by treatment with T3 at 10(-7)-10(-6) M. OCN production was increased dose dependently by this treatment with T3 (2.1-fold and 1.3-fold of control at 10(-8) M on days 11 and 28, respectively). Similar increases were observed in the levels of OCN mRNA. In addition, increases in phosphorylated OPN in the medium (day 11) and mineralized matrix (day 28) were observed (1.5-fold at 10(-8)-10(-6) M), while OPN synthesis and the level of its mRNA were depressed by T3 (60-70% of control at 10(-8) M). These results suggest that T3 regulates osteoblastic differentiation and activity depending on the state of cell differentiation: T3 suppresses the differentiation of osteoprogenitor cells to osteoblasts, but enhances the functional activity of mature osteoblasts.

Alkaline Phosphatase↗
PubMed1994

Anticipation in hereditary dentatorubral-pallidoluysian atrophy.

Anticipation refers to the progressively earlier onset and increase in disease severity in successive generations. We studied four families with hereditary dentatorubral-pallidoluysian atrophy (DRPLA), a neurodegenerative disease, and anticipation was present in the mode of inheritance. In subsequent generations DRPLA shows an earlier onset and more severe as well as additional symptoms. Older onset patients suffer from cerebellar ataxia with or without dementia, whereas younger onset patients present as progressive myoclonus epilepsy syndrome, which consists of mental retardation, dementia, and cerebellar ataxia as well as epilepsy and myoclonus. Anticipation with paternal transmission was significantly greater than with maternal transmission.

Adult↗
PubMed1994

Enhancement of blood stasis and vascular permeability in Meth-A tumors by administration of hyperthermia in combination with tumor necrosis factor.

Blood stasis and vascular permeability induced by tumor necrosis factor (TNF) in Meth-A tumors transplanted in BALB/c mice were significantly enhanced by hyperthermia at 40 degrees C for 30 min immediately following TNF administration. A dose-dependent, sustained decline in the intratumoral blood flow rate occurred following the administration of TNF alone (i.v.; 5 x 10(3), 5 x 10(4), or 5 x 10(5) JRU/kg) and was enhanced by the administration of hyperthermia in combination with the TNF, even though no decline occurred with hyperthermia alone. The combination of TNF at 5 x 10(5) JRU/kg and hyperthermia resulted in a blood flow ratio (ratio of blood flow after administration to that before) of 0.47 at 1 h compared with a ratio of 0.65 at 1 h after TNF alone. The blood flow in normal skin sites did not decrease in any case. The permeability of the intratumoral vasculature similarly increased in a dose-dependent manner after the administration of TNF alone and was further increased by combination with hyperthermia, even though no increase occurred with hyperthermia alone. The mean permeability in mice receiving TNF alone at 5 x 10(5) JRU/kg was 1.35 times that in untreated mice. In mice receiving TNF at the same dose together with hyperthermia, the ratio was increased to 1.65. The results suggest that TNF selectively suppresses intratumoral blood flow, that this effect is enhanced by mild hyperthermia, and that the mechanism of the suppression by TNF with or without hyperthermia partly involves an increase in blood vessel permeability.

Animals↗
PubMed1994

Induction of synthesis of heat shock protein 72 in tumor necrosis factor gene-transduced cells.

Heat shock protein (HSP) and endogenous tumor necrosis factor (enTNF) both act as resistance factors against the cytotoxicity of various cellular stresses. To clarify the relationship between these two stress response systems, we investigated whether or not enTNF is capable of inducing HSP72. Without heating, no difference was found in HSP72 synthesis between enTNF-nonexpressing L-M cells and cells expressing L-R or L-M (pcDV-TNF). After initiation of heat treatment, however, a remarkable increase in HSP72 synthesis was noted in enTNF-expressing cells compared to enTNF-nonexpressing L-M cells. These findings indicated that enTNF augments heat-inducible HSP72 synthesis.

Animals↗
PubMed1994

The Ras/Raf signaling pathway is required for progression of mouse embryos through the two-cell stage.

We have used microinjection of antisense oligonucleotides, monoclonal antibody, and the dominant negative Ras N-17 mutant to interfere with Ras expression and function in mouse oocytes and early embryos. Microinjection of either ras antisense oligonucleotides or anti-Ras monoclonal antibody Y13-259 did not affect normal progression of oocytes through meiosis and arrest at metaphase II. However, microinjection of fertilized eggs with constructs expressing Ras N-17 inhibited subsequent development through the two-cell stage. The inhibitory effect of Ras N-17 was overcome by simultaneous injection of a plasmid expressing an active raf oncogene, indicating that it resulted from interference with the Ras/Raf signaling pathway. In contrast to the inhibition of two-cell embryo development resulting from microinjection of pronuclear stage eggs, microinjection of late two-cell embryos with Ras N-17 expression constructs did not affect subsequent cleavages and development to morulae and blastocysts. It thus appears that the Ras/Raf signaling pathway, presumably activated by autocrine growth factor stimulation, is specifically required at the two-cell stage, which is the time of transition between maternal and embryonic gene expression in mouse embryos.

Animals↗
PubMed1992

Endogenous tumor necrosis factor functions as a resistant factor against hyperthermic cytotoxicity.

One of the mechanisms of cytotoxicity by tumor necrosis factor (TNF) is the induction of reactive oxygen molecules. Cells producing endogenous tumor necrosis factor (enTNF) show resistance to the cytotoxicity of exogenous TNF by scavenging the reactive oxygen molecules. The intracellular hydroxyl radical production is also known to be involved in the heat-induced cytotoxicity. In the present study, we therefore examined the possibility that enTNF may act as a protective protein against the heat-induced cytotoxicity in a manner similar to that of exogenous TNF. Heat-sensitive L-M (mouse tumorigenic fibroblast) cells, originally expressing no enTNF, were transfected with a human TNF expression vector to produce enTNF. The stable transfectants showed apparent resistance to heat treatment. Conversely, when HeLa (human uterine cervical cancer) cells, originally producing an appreciable amount of enTNF, were transfected with an antisense TNF mRNA expression vector to inhibit enTNF synthesis, their heat sensitivity was enhanced. Furthermore, L-M cells which were transfected with nonsecretory human TNF expression vector also acquired resistance to heat treatment. In these cells, heat resistance correlated well with expression of enTNF and intracellular levels of manganous superoxide dismutase. These results indicate that enTNF exerts its intracellular protective effect against the heat-induced cytotoxicity by scavenging reactive oxygen with induced manganous superoxide dismutase in a manner similar to that found in cells treated with exogenous TNF.

Animals↗
PubMed1992

Endogenous tumor necrosis factor exerts its protective function intracellularly against the cytotoxicity of exogenous tumor necrosis factor.

Based on the findings that expression of endogenous tumor necrosis factor (enTNF), which is not present in TNF-susceptible cells, was generally observed in TNF-resistant cells and that TNF gene transfection gives rise to TNF resistance, the assumption was made that enTNF may be a protective protein against the cytotoxicity of exogenous TNF. However, it remains unknown whether the protection by enTNF is exerted in an intracellular or extracellular (autocrine) manner. We therefore transfected a nonsecretory human TNF gene (pTNF delta pro) into highly TNF-sensitive mouse tumorigenic fibroblasts (L-M cells) and investigated their TNF susceptibility. The transfectants expressed enTNF which was not secreted into the medium and acquired an appreciable degree of resistance to exogenous TNF. A significant increase in the manganous superoxide dismutase level was also noted in the transfectants. These findings suggest that enTNF exerts its protective function intracellularly by inducing manganous superoxide dismutase production.

Animals↗
PubMed1992

Induction of synthesis of manganous superoxide dismutase in L-M(pNTnF) cells carrying an inducible TNF gene.

Based on findings that the cytotoxic effects of tumor necrosis factor (TNF) are closely related to levels of intracellular oxygen radicals, and on the results of TNF gene transfection studies, the hypothesis was made that endogenous TNF (enTNF) acts as a protective factor against exogenous TNF by inducing inhibitors or scavengers of oxygen radicals. In order to test this hypothesis, we investigated the intracellular levels of manganous superoxide dismutase (MnSOD) and glutathione (GSH) in L-M(pNTnF) cells carrying a TNF gene induced by dexamethasone (DM). When L-M(pNTnF) cells were treated with DM they expressed enTNF, and acquired resistance to exogenous TNF. There was no change in the GSH concentration after enTNF induction, but a 1.9- to 3.9-fold increase in MnSOD levels was noted. Our findings suggest that enTNF exerts its protective function against the cytocidal effect of exogenous TNF by inducing MnSOD production.

Animals↗
PubMed1992

The role of 5'-methylthioadenosine on rat calvaria cell differentiation.

The role of 5'-methylthioadenosine (MTA), formed during the process of polyamine biosynthesis, on differentiation of osteoprogenitor cells was assessed by its effects on alkaline phosphatase (ALP) activity, bone nodule formation and osteopontin contents of cultured rat calvaria (RC) cells. These three markers were stimulated by exogenous MTA and were depressed by 5'-difluoromethylthioadenosine (DFMTA), a synthetic inhibitor of MTA phosphorylase, which cleaves MTA to adenine and 5-methylthioribose-1-phosphate. 5-Methylthioribose and 2-keto-4-methylthiobutyrate, metabolites of 5-methylthioribose-1-phosphate, had no effects on ALP activity and bone nodule formation in the presence or absence of DFMTA. On the other hand, adenine enhanced ALP activity, bone nodule formation and osteopontin contents in mineralized nodules and also partially reversed DFMTA-induced inhibition of these three markers. MTA, its metabolites and DFMTA did not affect the growth of RC cells under these culture conditions. These results suggest that adenine formed from MTA is important in the differentiation of RC cells.

Adenine↗
PubMed1992

Enhancement of lysosomal enzyme activity by recombinant human tumor necrosis factor and its role in tumor cell killing in vitro.

We investigated the effect of recombinant human tumor necrosis factor (TNF) on the lysosomal enzyme activity of various established cell lines in vitro. Incubation of 1 x 10(6) TNF-sensitive mouse tumorigenic fibroblasts (L-M cells) in the presence of TNF (100 U/ml) for 48 h increased the total (the sum of the enzyme activities in the lysosomes and the cytoplasm) acid phosphatase and beta-glucuronidase activities by 3.7- and 4.2-fold, respectively. The same increase was observed even when 1 U/ml of TNF was added to some cultures and no further augmentation occurred at 10 or 100 U/ml. Measurement of total and free enzyme activities showed that TNF stimulation not only enhanced the total intracellular enzyme activity but also accelerated the conversion into free (cytoplasmic) enzyme activity. Addition of a lysosomotropic agent (methylamine) suppressed both the enhancement of lysosomal enzyme activity and the cytotoxicity of TNF. A similar enhancement of lysosomal enzyme activities was also detected in various TNF-sensitive tumor cell lines, and a strong correlation (acid phosphatase: r = 0.836, beta-glucuronidase: r = 0.910) was observed between the enhancement of enzyme activity and sensitivity to TNF. No such increase was detected in TNF-resistant human diploid cells. These results show that TNF induces the activation and release of lysosomal enzymes in TNF-sensitive cells, and suggest that such events may play an important role in TNF-mediated cytotoxicity.

Acid Phosphatase↗