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Biomedical subjects

N Yamauchi

Publications and source records attributed to N Yamauchi.

At least 55 records · Page 3Linked to original sources
PubMed1998

The growth hormone secretagogue KP-102-induced stimulation of food intake is modified by fasting, restraint stress, and somatostatin in rats.

The effects of fasting, restraint stress, and intracerebroventricular (i.c.v.) injection of somatostatin on the growth hormone secretagogue, KP-102-induced stimulation of food intake were examined in rats. KP-102-induced stimulation of food intake was observed in freely-fed rats but not in 24-h starved rats. A 90 min period of restraint stress decreased food intake, and i.c.v. administration of KP-102 counteracted the suppressive effect of restraint on food intake. I.c.v. administration of somatostatin partially attenuated the KP-102-induced stimulation of food intake in freely-fed rats, while somatostatin itself did not change food intake. These results suggest that the stimulatory effect of KP-102 on feeding behavior is evident in freely-fed rats but not in starved rats, and that the effect of KP-102 is counteracted or attenuated by stress or somatostatin.

Animals↗
PubMed1998

Differentiation induction by a tumor-necrosis-factor mutant 471 in human myelogenous leukemic cells via tumor-necrosis-factor receptor-p55.

The present study examined differentiation-inducing activity by various tumor-necrosis-factor(TNF) mutants against the human leukemic cell lines HL-60 and U-937. Mutant TNF 471, from which 7 N-terminal amino acids of native TNF were deleted and Pro8, Ser9 and Asp10 were replaced by Arg, Lys and Arg, possessed the highest activity among the TNF mutants, and its activity was 120-fold that of native TNF. The various biological activities of TNF were signaled through 2 distinct receptors, p55 and p75. Although cytotoxicity was reported to involve mainly p55, this differentiation-inducing activity was not well understood. The fact that the affinity of TNF 471 was higher to p55 and lower to p75 than that of native TNF by a binding competition assay suggested that the differentiation-inducing activity was also signaled through p55. To verify this hypothesis, the human myelogenous leukemic cell line, KG-1, which scarcely expresses either receptor and does not differentiate with TNF, was transduced with the p55 or p75 gene. Subsequently p55 transfectants manifested a greater ability to differentiate; however, p75 transfectants did not differ from parental cells or from mock-transfectants. Further, the differentiation of p55 transfectants induced by TNF was reduced by the inhibitor of protein-kinase-C (PKC), staurosporine. These results indicate that the differentiation-inducing activity was signaled through the TNF receptor, p55, via PKC and that the excellent ability of TNF 471 to induce differentiation was related to its high affinity for p55.

Antigens, CD↗
PubMed1998

Suppression of intracellular resistance factors by adriamycin augments heat-induced apoptosis via interleukin-1beta-converting enzyme activation in pancreatic carcinoma cells.

Combination of heat and various anticancer drugs can exert a synergistic antitumor effect in vitro and in vivo, though the mechanism is not clear. We have previously shown that endogenous tumor necrosis factor (enTNF) acts as an intracellular resistance factor to inhibit the cytotoxic effect of heat by scavenging oxygen-free radicals via the induction of manganous superoxide dismutase (MnSOD). Consequently, we examined whether the suppression of these resistance factors by combining anticancer drugs and heat causes an augmentation of heat-induced cytotoxicity. The human pancreatic carcinoma cell line, PANC-1, constitutively expresses appreciable amounts of enTNF and also demonstrates heat resistance. After treatment of these cells for 15 hr with adriamycin (ADM), the expression of enTNF was decreased by 43%, and MnSOD activity was suppressed by 55%. The cytotoxic effects of the treatment of PANC-1 cells with ADM followed by heat were greater than the sum of those observed with the agents administrated individually. Heat-induced apoptosis was also augmented by pretreatment with ADM. Furthermore, the interleukin-1beta-converting enzyme inhibitor, Ac-YVAD-CMK, reversed the augmented cytotoxicity. Our results indicate that suppression of intracellular resistance factors such as enTNF and MnSOD plays an important role in apoptosis seen after heat and ADM combined therapy.

Apoptosis↗
PubMed1998

An apoptosis-inducing gene therapy for pancreatic cancer with a combination of 55-kDa tumor necrosis factor (TNF) receptor gene transfection and mutein TNF administration.

Intratumoral injection of recombinant human tumor necrosis factor (TNF) for inoperable pancreatic cancer has shown some efficacy in suppressing tumor growth or decreasing tumor markers. However, complete regression has not yet been achieved, possibly due to a lack of TNF receptors on tumor cells or an abundance of intracellular resistance factors. Recently, two distinct types of TNF receptors, R55 and R75, were identified, which are responsible for signaling of cytotoxicity and of proinflammation, respectively. In this study, a novel type of suicide gene therapy is proposed that is based on transfection of the R55 gene into human pancreatic cancer cells (AsPC-1 and PANC-1) and subsequent administration of TNF. The transfectants from both cell lines showed higher TNF susceptibility than their parental cells. In vivo tumor formation of an AsPC-1 clone (clone 10) inoculated in nude mice was substantially suppressed by administration of TNF. For practical use of this strategy, however, the adverse effects of TNF may become an obstacle. We previously produced mutein TNF 471, which had a higher affinity for R55, superior antitumor activity, and fewer adverse effects. This mutein TNF 471 manifested greater antitumor activity against clone 10. Because the R55 receptor is known to be involved in augmentation of cellular immunity by TNF, mutein TNF 471 is also expected to be highly potent in this function. In fact, the mutein TNF 471 induced higher splenic natural killer cell activity in nude mice inoculated with clone 10 than did native TNF. This property of augumenting cellular responses may be advantageous in the eradication of viable tumor cells left untransfected in practical gene therapy regimens in which 100% transfection of the R55 gene into tumors is not feasible. Thus, gene therapy combining transfection of the TNF-R55 gene with administration of mutein TNF 471 may provide a new modality for the treatment of pancreatic cancer.

Adenocarcinoma↗
PubMed1998

Substrate specificity of 2-deoxy-scyllo-inosose synthase, the starter enzyme for 2-deoxystreptamine biosynthesis, toward deoxyglucose-6-phosphates and proposed mechanism.

A crucial enzyme in the biosynthesis of the 2-deoxystreptamine aglycon of clinically important aminocyclitol antibiotics is 2-deoxy-scyllo-inosose synthase (DOIS), which is responsible for the initial carbocycle formation of 2-deoxy-scyllo-inosose (1) from D-glucose-6-phosphate (G-6-P) (2). To get more insight into the mechanism and substrate specificity, deoxy-D-glucose-6-phosphates (deoxy-G-6-P) were chemically synthesized and subjected to the reaction with DOIS. The enzyme appeared to use 2-deoxy- and 3-deoxy-G-6-P as substrates, both of which were converted into the corresponding dideoxy-scyllo-inosose products, but 4-deoxy-G-6-P failed in cyclization by DOIS. These results clearly support the proposed reaction mechanism involving the initial oxidation at C-4 of the G-6-P substrate. Another implication is the potential use of DOIS for the preparation of useful dideoxyinososes.

Chromatography, High Pressure Liquid↗
PubMed1998

Interleukin-1beta administered intracerebroventricularly stimulates the release of noradrenaline in the hypothalamic paraventricular nucleus via prostaglandin in the rat.

We evaluated the effect of intracerebroventricular (i.c.v.) administration of interleukin (IL)-1beta on the rectal temperature and the release of noradrenaline (NA) in the hypothalamic paraventricular nucleus (PVN) of the rat. IL-1beta increased rectal temperature at doses ranging from 300 pg to 300 ng, whereas it, at doses ranging from 3 ng to 300 ng, significantly stimulated the release of NA in the PVN measured by intracerebral microdialysis. The stimulatory effect of IL-1beta on the release of NA was blocked by the subcutaneous injection of indomethacin. These findings suggest that IL-1beta stimulates the release of NA in the PVN via prostaglandin, and that the release of NA in the PVN is not necessarily related to the increase in body temperature.

Animals↗
PubMed1998

[Gene delivery into human cancer cells via transferrin receptor].

At present, vectors widely used for gene transduction are retroviruses and adenoviruses. However, the transduction using these vectors are primarily conducted ex vivo. The direct in vivo gene delivery method to target tumor cells are required. Trials to augment specificity of gene targeting to tumor cells have been in progress including approaches to use modified virus particles by gene technology instead of wild type particles or to take advantage of ligand-receptor or antibody-antigen systems by allowing vector DNAs to bind these ligand and antibodies. Transferrin receptor (TfR) is widely distributed on actively proliferating cells and is therefore an appropriate target for in vivo gene delivery into those cells. We developed a simple method to conjugate biotinylated double-stranded DNA to biotinylated Tf via streptavidin and demonstrated successful transduction of the conjugate into TfR-positive human cancer cells. The present method may provide a novel technique for gene transduction, which may be used especially to transfer various DNA vectors into cells specifically expressing TfR, in vivo as well as in vitro.

Adenoviridae↗
PubMed1998

[Clinical study of synchronous double cancers of the lung and digestive tract].

Among 64 cases of surgically resected primary lung cancer from 1991 to 1997, there were 5 cases of synchronous double cancers of the lung and digestive tract. They were consisted of 4 males and 1 female and the patient age at the time of the lung resection ranged from 65 to 81 years (average: 74.6). One male was diagnosed as having lung cancer (squamous cell carcinoma) along with sigmoid colon cancer (adenocarcinoma) and others were lung cancer (adenocarcinoma) and gastric cancer (adenocarcinoma). In two patients with early gastric cancer, lobectomies were performed following endoscopic resection of gastric cancer. In three patients including two old man and woman (over 80 years old), lobectomies and gastrectomies (or sigmoidectomy) were performed at the same time. We omitted mediastinal lymph nodes dissections in two old patients and no operative complications occurred. All patients are alive now. It can be concluded that in cases of synchronous double cancers of the lung and digestive tract, we must select the best treatment that is not invasive for the patient and that simultaneous operation for double cancer can be safely performed.

Adenocarcinoma↗
PubMed1997

Brain beta-endorphin and other opioids are involved in restraint stress-induced stimulation of the hypothalamic-pituitary-adrenal axis, the sympathetic nervous system, and the adrenal medulla in the rat.

Opiates and opioids have complex effects on the hypothalamic-pituitary-adrenal axis, and they stimulate the sympathetic nervous system. This study was designed to clarify the role of brain beta-endorphin in the mechanism by which stress increases plasma concentrations of adrenocorticotropin (ACTH), epinephrine (E), and norepinephrine (NE). Intracerebroventricular (i.c.v.) administration of beta-endorphin to rats significantly increased plasma ACTH levels at doses of 0.09, 0.3, and 1.5 nmol, and plasma E and NE levels at doses of 0.3 and 1.5 nmol. The rise of plasma ACTH, E, and NE levels by 0.3 nmol beta-endorphin was inhibited by intravenous (i.v.) administration of 2 mg/kg b.wt. naloxone. I.v. administration of anti-rat corticotropin-releasing hormone (CRH) rabbit serum completely blocked the beta-endorphin-induced ACTH secretion without affecting the secretion of E and NE. I.c.v. administration of anti-beta-endorphin rabbit gamma-globulin attenuated a 30-min restraint stress-induced rise of plasma ACTH levels without significant influence on the rise of E and NE levels, whereas i.v. administration of naloxone attenuated the restraint stress-induced rise of plasma ACTH, E and NE levels. These results suggest that i.c.v. administration of beta-endorphin stimulates the secretion of ACTH, E, and NE through opiate receptor, and that brain CRH mediates the beta-endorphin-induced secretion of ACTH. The results also suggest that brain beta-endorphin is, at least in part, involved in the restraint stress-induced stimulation of the hypothalamic-pituitary-adrenal axis, and that some opioids other than beta-endorphin are involved in the stimulatory mechanism of the autonomic nervous system and the adrenal medulla in the rat.

Adrenal Medulla↗
PubMed1997

Inhibition of osteoblastic cell differentiation by conditioned medium derived from the human prostatic cancer cell line PC-3 in vitro.

Human prostatic carcinoma frequently metastasizes to bone tissue and activates bone metabolism, especially bone formation, at the site of metastasis. It has been reported that an extract of prostatic carcinoma and conditioned medium (CM) of a human prostatic carcinoma cell line, PC-3, established from a bone metastastic lesion, stimulate osteoblastic cell proliferation. However, there is little information about the effect of PC-3 CM on the differentiation of osteoblastic cells. In this study, we investigated the effect of PC-3 CM on the differentiation of two types of osteoblastic cells, primary fetal rat calvaria (RC) cells containing many undifferentiated osteoprogenitor cells, and ROS 17/2.8, a well-differentiated rat osteosarcoma cell line. PC-3 CM inhibited bone nodule formation and the activity of alkaline phosphatase (ALPase), an osteoblastic marker enzyme, on days 7, 14, and 21 (RC cells) or 3, 6, and 9 (ROS 17/2.8 cells) in a dose-dependent manner (5-30% CM). However, the CM did not affect cell proliferation or cell viability. PC-3 CM was found to markedly block the gene expression of ALPase and osteocalcin (OCN) mRNAs but had no effect on the mRNA expression of osteopontin (OPN), the latter two being noncollagenous proteins related to bone matrix mineralization. These findings suggest that PC-3 CM contains a factor that inhibits osteoblastic cell differentiation and that this factor may be involved in the process of bone metastasis from prostatic carcinoma.

Alkaline Phosphatase↗
PubMed1997

Endogenous tumor necrosis factor as a predictor of doxorubicin sensitivity in leukemic patients.

We have previously reported that intracellular tumor necrosis factor (enTNF) is responsible for resistance, in established cell lines to doxorubicin (DOX), exogenous TNF, and heat stress by inducing manganous superoxide dismutase (MnSOD), thereby scavenging reactive oxygen free radicals. Leukemic cells from 19 patients (6 acute lymphoblastic leukemia, 13 acute myeloid leukemia) were examined for their sensitivity to DOX and TNF in relation to their enTNF expression and MnSOD activity. Sensitivity to DOX and the expression of enTNF or MnSOD activity were inversely correlated. In a case with acquired resistance to chemotherapy which included DOX, enTNF expression and MnSOD activity were increased. Furthermore, in 14 cases treated with a regimen including an anthracycline, 4 cases that failed to respond to chemotherapy showed relatively high amounts of enTNF expression. KG-1 (human acute myelogenous leukemia) cells transfected with a nonsecretory-type TNF expression vector (pTNF delta pro) showed resistance to DOX. A significant increase in MnSOD levels was also noted in the transfectants. TNF antisense cDNA was transfected into isolated leukemic cells from five patients. Sensitivity of the antisense transfectants to DOX was increased, approximately 1.4- to 2.5-fold. These results suggest that enTNF acts as a resistance factor against DOX in leukemia, and that enTNF may be useful as a predictor of DOX sensitivity in leukemia.

Acute Disease↗
PubMed1997

Induction of heat shock protein 72 synthesis by endogenous tumor necrosis factor via enhancement of the heat shock element-binding activity of heat shock factor 1.

Endogenous tumor necrosis factor (enTNF) acts as a resistance factor against cytotoxicity caused by heat by inducing manganous superoxide dismutase (MnSOD), thereby scavenging reactive oxygen free radicals. On the other hand, it is also well known that heat shock proteins (HSP) which are induced by heat stress behave as cytoprotective factor against this stress. However, the relationship of these two resistance factors is not elucidated yet. In the present study, we therefore proposed the possibility that enTNF enhances HSP72 expression. Heat-sensitive L-M (mouse tumorigenic fibroblast) cells, which normally do not express enTNF, were transfected with a nonsecretory-type human TNF-alpha expression vector to produce enTNF. Stable transfectants showed resistance to heat treatment and an increase of HSP72 expression. Conversely, when HeLa (human uterine cervical cancer) cells, which normally produce an appreciable amount of enTNF, were transfected with an antisense TNF-alpha mRNA expression vector to inhibit enTNF synthesis, their heat sensitivity was enhanced and HSP72 expression was reduced by half. Although enTNF caused no difference in the level of heat shock factor (HSF) 1 in these cells, enTNF expression correlated well with the binding activity of HSF-1 to a 32P-labeled synthetic oligonucleotide containing the human heat shock element (HSE). These results indicate that enTNF participates not only in intrinsic resistance against heat via induction of MnSOD but also via enhancement of the HSE-binding activity of HSF 1 followed by augmentation of HSP72 expression.

Animals↗
PubMed1997

Kinetic isotope effect and reaction mechanism of 2-deoxy-scyllo-inosose synthase derived from butirosin-producing Bacillus circulans.

The mechanism of 2-deoxy-scyllo-inosose synthase reaction, a carbocycle formation step from D-glucose-6-phosphate in the biosynthesis of the 2-deoxystreptamine aglycon of clinically important aminocyclitol antibiotics, was investigated with a partially purified enzyme from butirosin-producing Bacillus circulans SANK 72073, Nonlabeled and double-labeled D-[4-2H, 3-15O]glucose-6-phosphate were used for cross-over experiment, and the oxime-TMS ether derivative of the 2-deoxy-scyllo-inosose product was analyzed by GC-MS. The deuterium label at C-4 of the substrate appeared to be retained at C-6 of the inosose product without scrambling of the double-labeled isotopes. Since the transient reduction of NAD+ cofactor was proved to be essential in the 2-deoxy-scyllo-inosose reaction, the hydride abstraction and returning appeared to take place within the same glucose molecule. The observed kinetic isotope effect was estimated to be kH/kD = 2.4. These results strongly suggest that this carbocycle formation is catalyzed by a single 2-deoxy-scyllo-inosose synthase enzyme with catalytic requirement of NAD+, the mechanism of which appears to be resembled closely to the 2-deoxy-scyllo-inosose synthase in the Streptomyces fradiae.

Anti-Bacterial Agents↗
PubMed1997

[TNF].

TNF exerts its biological activities through two distinct receptors of TNF-R55 and TNF-R75. Recent studies have identified TNF receptor-associated molecules, and intracellular signal transduction for apoptosis induced by TNF has been elucidated. Various TNF mutants with higher affinity to TNF-R55 and lower affinity to TNF-R75 are being clarified biogenetically. These mutants show lower adverse effect and higher antitumor activity. Furthermore, TNF gene transduction into lymphocytes and tumor cells shows a decrease in tumorigenicity and enhancement of host immunogenicity. This approach appears to be promising for cancer treatment.

Animals↗
PubMed1997

[Granulocyte colony stimulating factor (G-CSF) producing renal cell carcinoma].

A 88-year-old male patient with G-CSF producing renal cell carcinoma is reported. The patient was admitted to our hospital complaining of macrohematureia. The laboratory examination showed marked leukocytosis of 18,200/microliter (neutrophil 92%) in the peripheral blood and high levels of G-CSF (120 pg/ml) in the serum. An abdominal CT scan revealed a right renal tumor. The neutrophil count rose to 38,700/microliter with increasing of tumor size. Histopathological diagnosis was renal cell carcinoma (Grade 3) and immunohistochemical staining using Histo anti-G-CSF antibody demonstrated cancer cells produced G-CSF. This is the second case of G-CSF producing renal cell carcinoma diagnosed by immunohistochemical staining in the literature.

Aged↗
PubMed1996

Intracerebroventricular administration of beta-endorphin increases the expression of c-fos and of corticotropin-releasing factor messenger ribonucleic acid in the paraventricular nucleus of the rat.

We evaluated the effects of intracerebroventricular (i.c.v.) administration of beta-endorphin and naloxone, an opioid antagonist, on the induction of c-fos and corticotropin-releasing factor (CRF) mRNA to clarify the effects of beta-endorphin on cellular activity and CRF gene expression in the paraventricular nucleus (PVN) of the rat using in situ hybridization. A significant induction of c-fos mRNA was noted in the PVN after i.c.v. injection of beta-endorphin, compared to control. This induction was inhibited by the administration of naloxone. A significant increase in CRF mRNA levels in the PVN was observed 120 min after the i.c.v. injection of beta-endorphin. This increase was partially, but significantly, inhibited by naloxone administration. In addition, i.c.v. administration of beta-endorphin increased plasma ACTH concentration in freely moving rats, which was inhibited by intravenous injection of CRF antiserum. These results suggest that the i.c.v. injection of beta-endorphin increases the neuronal activity and the biosynthesis of CRF in the PVN, and stimulates the secretion of ACTH by increasing CRF secretion. This effect on the PVN was mediated, at least in part, via the opioid receptor.

Animals↗
PubMed1996

Effect of culture conditions on artificial activation of porcine oocytes matured in vitro.

The effects of culture media used and culture period for in vitro maturation of porcine oocytes on their subsequent response to chemical and electrical activation, were investigated. Activated oocytes were identified by the presence of a pronucleus(ei) or cleavage. Porcine oocytes were cultured for 24, 30, 36, 42 and 48 h in TCM199 with Earle's salts (199) supplemented with 10% fetal calf serum (199-FCS) before electrical stimulation. Although few oocytes were activated after 24 h and 30 h of culture (5.4% and 6.1% respectively), the percentage of activated oocytes increased significantly to 93.2% after 42 h in culture (P < 0.05); however, when the culture period was extended to 48 h, there was a significant decrease to 56.7% (P < 0.05). Oocytes were also cultured in four types of media: (1) 199-FCS; (2) 199 supplemented with 5 mg mL-1 bovine serum albumin (199-BSA); (3) Kreb's-Ringer bicarbonate solution supplemented with 10% FCS (KRB-FCS); and (4) KRB supplemented with BSA (KRB-BSA). After 42 h of culture in each medium, the oocytes were electrically activated. Although rates of maturation of oocytes cultured in the four media were similar (74.0-80.8%), all oocytes except those cultured in 199-FCS failed to be activated. In addition, oocytes were cultured for 36, 42 and 48 h in 199-FCS and then stimulated by treatment with ethanol. Significantly fewer oocytes were activated in the chemically-treated group than in the electrically-treated group. These results indicate that culture conditions used for the culture of porcine oocytes in vitro are important with respect to their subsequent response to artificial activation.

Animals↗