Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 397 records · Page 22Linked to original sources

PubMed1998

Alteration of hormone levels in transgenic tobacco plants overexpressing the rice homeobox gene OSH1.

The rice (Oryza sativa L.) homeobox gene OSH1 causes morphological alterations when ectopically expressed in transgenic rice, Arabidopsis thaliana, and tobacco (Nicotiana tabacum L.) and is therefore believed to function as a morphological regulator gene. To determine the relationship between OSH1 expression and morphological alterations, we analyzed the changes in hormone levels in transgenic tobacco plants exhibiting abnormal morphology. Levels of the plant hormones indole-3-acetic acid, abscisic acid, gibberellin (GA), and cytokinin (zeatin and trans-zeatin [Z]) were measured in leaves of OSH1-transformed and wild-type tobacco. Altered plant morphology was found to correlate with changes in hormone levels. The more severe the alteration in phenotype of transgenic tobacco, the greater were the changes in endogenous hormone levels. Overall, GA1 and GA4 levels decreased and abscisic acid levels increased compared with wild-type plants. Moreover, in the transformants, Z (active form of cytokinin) levels were higher and the ratio of Z to Z riboside (inactive form) also increased. When GA3 was supplied to the shoot apex of transformants, internode extension was restored and normal leaf morphology was also partially restored. However, such GA3-treated plants still exhibited some morphological abnormalities compared with wild-type plants. Based on these data, we propose the hypothesis that OSH1 affects plant hormone metabolism either directly or indirectly and thereby causes changes in plant development.

Homeodomain Proteins↗

PubMed1998

Decreased GA1 content caused by the overexpression of OSH1 is accompanied by suppression of GA 20-oxidase gene expression.

We previously reported that overexpression of the rice homeobox gene OSH1 led to altered morphology and hormone levels in transgenic tobacco (Nicotiana tabacum L.) plants. Among the hormones whose levels were changed, GA1 was dramatically reduced. Here we report the results of our analysis on the regulatory mechanism(s) of OSH1 on GA metabolism. GA53 and GA20, precursors of GA1, were applied separately to transgenic tobacco plants exhibiting severely changed morphology due to overexpression of OSH1. Only treatment with the end product of GA 20-oxidase, GA20, resulted in a striking promotion of stem elongation in transgenic tobacco plants. The internal GA1 and GA20 contents in OSH1-transformed tobacco were dramatically reduced compared with those of wild-type plants, whereas the level of GA19, a mid-product of GA 20-oxidase, was 25% of the wild-type level. We have isolated a cDNA encoding a putative tobacco GA 20-oxidase, which is mainly expressed in vegetative stem tissue. RNA-blot analysis revealed that GA 20-oxidase gene expression was suppressed in stem tissue of OSH1-transformed tobacco plants. Based on these results, we conclude that overexpression of OSH1 causes a reduction of the level of GA1 by suppressing GA 20-oxidase expression.

Amino Acid Sequence↗

PubMed1998

Oral administration of a Kampo (Japanese herbal) medicine Juzen-taiho-to inhibits liver metastasis of colon 26-L5 carcinoma cells.

We have investigated the inhibitory effect of oral administration of Juzen-taiho-to, a Kampo Japanese herbal medicine, on liver metastasis by the inoculation of a liver-metastatic variant (L5) of murine colon 26 carcinoma cells into the portal vein. Oral administration of Juzen-taiho-to for 7 days before tumor inoculation resulted in dose-dependent inhibition of liver tumor colonies and significant enhancement of survival rate as compared with the untreated control, without side effects. We also found that liver metastasis of L5 cells was enhanced in BALB/c mice pretreated with anti-asialo GM1 serum or 2-chloroadenosine, and in BALB/c nu/nu mice, compared to normal mice. This indicates that NK cells, macrophages, and T-cells play important roles in the prevention of metastasis of tumor cells. Juzen-taiho-to significantly inhibited the experimental liver metastasis of colon 26-L5 cells in mice pretreated with anti-asialo GM1 serum and untreated normal mice, whereas it did not inhibit metastasis in 2-chloroadenosine-pretreated mice or T-cell-deficient nude mice. Oral administration of Juzen-taiho-to activated peritoneal exudate macrophages (PEM) to become cytostatic against the tumor cells. These results show that oral administration of Juzen-taiho-to inhibited liver metastasis of colon 26-L5 cells, possibly through a mechanism mediated by the activation of macrophages and/or T-cells in the host immune system. Thus, Juzen-taiho-to may be efficacious for the prevention of cancer metastasis.

2-Chloroadenosine↗

PubMed1998

Efficacy of L-846 in patients with insomnia: evaluation by polysomnography.

The effects of L-846, an ultra-short-acting pyrazolopyrimidine hypnotic, on sleep were studied in nine insomniacs and two neurotic patients with insomnia. The patients were randomly assigned to receive 5 mg (n=6) or 10 mg (n=5) L-846. The study schedule comprised of one adaptation night, two baseline nights, three drug nights, and two withdrawal nights. Sleep latency and slow wave sleep (SWS) latency was largely shortened and %SWS increased in the early phase of sleep. No clear evidence of rebound insomnia was noted.

Acetamides↗

PubMed1998

Wrist activity rhythm and sleep diary of delayed sleep phase syndrome.

Wrist activity rhythm and sleep diary data in a case of delayed sleep phase syndrome were investigated. The sleep self-estimation was nearly compatible with the activity levels of the actigraph. The actigraphic data were also analyzed. The subject's most fixed period of activity was 24.31 h, and acrophase (time of day) that fixed the data to a 24 h period was 03.25 h. The subject has had reversed night and day sleep patterns for more than 7 years. It was very difficult to advance the sleep phase when the delayed phase has been continuous long-term under the state of poor social cues.

Activity Cycles↗

PubMed1998

Time course of saliva and serum melatonin levels after ingestion of melatonin.

Salival and serum melatonin levels after melatonin ingestion were measured by gas chromatography-mass spectrometry. Ingestion of 3 mg melatonin caused a marked increase in serum melatonin (3561+/-1201 pg/mL) within 20 min, followed by a gradual decrease, but the level still remained higher than the basal level at 240 min after the ingestion. The saliva melatonin 60 min after the ingestion showed the highest level (1177+/-403 pg/mL) which was one-third of the plasma level. The saliva melatonin level was highly correlated with the serum level throughout the experimental period (r=0.82, P=0.0001). These data indicate that the measurement of saliva melatonin level may be a suitable indicator for the melatonin secretion into general circulation.

Adult↗

PubMed1998

Growth on urea can trigger death and peroxidation of the cyanobacterium Synechococcus sp. strain PCC 7002.

Laboratory conditions have been identified that cause the rapid death of cultures of cyanobacteria producing urease. Once the death phase had initiated in the stationary growth phase, cells were rapidly bleached of all pigmentation. Null mutations in the ureC gene, encoding the alpha subunit of urease, were constructed, and these mutants were no longer sensitive to growth in the presence of urea. High levels of peroxides, including lipid peroxides, were detected in the bleaching cells. Exogenously added polyunsaturated fatty acids triggered a similar death response. Vitamin E suppressed the formation of peroxides and delayed the onset of cell bleaching. The results suggest that these cyanobacterial cells undergo a metabolic imbalance that ultimately leads to oxidative stress and lipid peroxide formation. These observations may provide insights into the mechanism of sudden cyanobacterial bloom disappearance in nature.

Cyanobacteria↗

PubMed1998

Effect of the leukotriene receptor antagonist pranlukast on cellular infiltration in the bronchial mucosa of patients with asthma.

BACKGROUND: It has been reported that pranlukast reduces the antigen induced immediate and late phase asthmatic responses, airway hyperreactivity to acetylcholine, and pulmonary eosinophil accumulation in guinea pigs. A study was undertaken to test the hypothesis that pranlukast may reduce the number of inflammatory cells in the bronchial mucosa of patients with asthma. METHODS: A double blind, placebo controlled study was performed in 17 mild to moderate asthmatic subjects to examine changes in inflammatory cell infiltration in response to pranlukast (225 mg orally twice per day for four weeks). Comparisons of the mean daily beta 2 agonist use, symptom score, FEV1 percentage predicted, and airway methacholine responsiveness were made before and after treatment. Using fibreoptic bronchoscopy, bronchial biopsy specimens were obtained before and after treatment with either pranlukast (n = 10) or placebo (n = 7). Immunohistology was performed using monoclonal antibodies for CD3, CD4, CD8, CD68, NP57, AA1, EG1, EG2, gamma GTP and CD19. RESULTS: When the pranlukast and placebo treated groups were compared there were decreases in beta 2 agonist use, symptom score, and airway methacholine responsiveness after pranlukast but no increase in FEV1 was seen. The clinical response in patients treated with pranlukast was accompanied by a reduction in CD3 (median difference -37, 95% confidence interval (CI) -69 to -1; p < 0.05), CD4 (median difference -28, 95% CI -49 to -8; p < 0.01), AA1 (median difference -15, 95% CI -26 to 0; p < 0.05) and EG2 positive cells (95% CI -35 to 0; p < 0.05), but not in EG1 positive eosinophils, gamma GTP positive cells, and CD19 positive plasma cells. CONCLUSIONS: These results support the view that pranlukast may act by inhibition of bronchial inflammation in patients with asthma.

Adrenergic beta-Agonists↗

PubMed1998

Cloning of rat eotaxin: ozone inhalation increases mRNA and protein expression in lungs of brown Norway rats.

The C-C chemokine eotaxin is thought to be important in the selective recruitment of eosinophils to the site of inflammation in guinea pigs, mice, and humans. We isolated the rat eotaxin gene to determine whether a similar molecule might play a role in the pulmonary infiltration of eosinophils during acute inflammation in the rat. The cDNA for rat eotaxin encoded a 97-amino acid protein containing a 74-amino acid mature eotaxin protein with 97.3% identity to mouse eotaxin. The recombinant protein encoded by this gene displayed specific chemotactic activity for eosinophils when analyzed with a microchemotactic chamber. The expression of eotaxin mRNA increased approximately 1.6-fold immediately after exposure to ozone and was 4-fold higher after 20 h. The number of lavageable eosinophils at the same time points were 3- and 15-fold greater, respectively, than control eosinophils. Immunocytochemistry revealed that alveolar macrophages and bronchial epithelial cells were positive for eotaxin. These results suggest that eotaxin may be involved in the recruitment of eosinophils into the air spaces during certain inflammatory conditions in rats.

Administration, Inhalation↗

PubMed1998

Requirement of estrogen receptor expression and function for [12Val] K-Ras-mediated NIH3T3 cell transformation.

We investigated the biological significance of estrogen receptors (ERs) in NIH3T3 cell transformation by the [12Val] K-Ras mutant. This mutant enhanced the steady-level and transcriptional activity of ER. Coexpression of the progesterone receptor with mutant K-Ras led to suppression of tumorigenicity and inhibition of the activation of ER. The antisense oligomers complementary to the ER suppressed proliferation and transformed phenotypes of K12V cells. These observations support the importance of ER in Ras-mediated cell transformation.

Cell Transformation, Neoplastic↗

PubMed1998

Enhancing effect of 2-O-alpha-D-glucopyranosyl-L-ascorbic acid, a stable ascorbic acid derivative, on collagen synthesis.

The objective of the present study was to compare 2-O-alpha-D-glucopyranosyl-L-ascorbic acid (AA-2G) with ascorbic acid (AA) and ascorbic acid 2-phosphate (AA-2P) concerning the promotion of collagen production in human skin fibroblasts. Though AA-2G was still observed to be promoting collagen synthesis at the same level on the 8th day of the culture, collagen synthesis was seen to decrease on the fifth day of culturing with AA and AA-2P. This sustained collagen synthesis-promoting action is considered to be a major feature of the novel vitamin C derivative, AA-2G by conducting an experiment in which an alpha-glucosidase inhibitor was present, it was shown that AA-2G exerts its collagen synthesis-promoting action after being decomposed to AA by alpha-glucosidase. Further, we observed that for AA-2G, even on the 8th day of the culture, the amount of AA in the fibroblasts was virtually unchanged from the beginning of the experiment, whereas, in the case of adding AA and AA-2P, virtually no AA was detectable in the culture medium on the fifth day. These findings suggests that AA-2G is decomposed to AA by alpha-glucosidase in the cells. This AA promotes collagen synthesis, which is prolonged through AA-2G's sustained decomposition.

Ascorbic Acid↗

PubMed1998

Expression of the anti-metastatic effect induced by Juzen-taiho-to is based on the content of Shimotsu-to constituents.

We investigated the inhibitory effect of oral administration of Juzen-taiho-to, a Kampo Japanese herbal medicine, and its related formulations on the experimental liver and lung metastasis of tumor cells in vivo. Oral administration of Juzen-taiho-to for 7 d before tumor inoculation significantly reduced the number of liver metastatic colonies of colon 26-L5 carcinoma cells and attenuated the increase of liver weight in a dose-dependent manner ranging from 4 to 40 mg/d. Its oral administration for this same period before tumor inoculation also significantly inhibited lung metastasis of B16-BL6 melanoma cells. Juzen-taiho-to originally consisted of 8 crude drugs derived from Shimotsu-to and Shikunshi-to prescriptions together with two crude drugs (Cinnamomi Cortex and Astragali Radix). Oral administration of Shimotsu-to as well as Juzen-taiho-to for 7 d before tumor inoculation resulted in a significant reduction in the number of metastatic colonies and the liver weight as compared with the control, whereas Shikunshi-to did not exhibit such an inhibitory effect. Unsei-in containing four Shimotsu-to constituents was also active in inhibiting liver metastasis. Toki-shakuyaku-san and Ninjin-yoei-to, which include all Shimotsu-to constituents except Rehmanniae Radix and Cnidii Rhizoma, respectively, did not show a significant anti-metastatic effect. Rikkunshi-to and Ninjin-yoei-to, which contain Shikunshi-to constituents, did not affect the inhibition of liver metastasis. Hochu-ekki-to treatment before tumor inoculation also led to a significant inhibition of liver metastasis, probably through an inhibitory mechanism different from Juzen-taiho-to. These results suggest that the anti-metastatic effect of Juzen-taiho-to is partly associated with its Shimotsu-to-derived constituents.

Animals↗

PubMed1998

Comparison of thrombolytic therapies with mutant tPA (lanoteplase/SUN9216) and recombinant tPA (alteplase) for acute myocardial infarction.

The fibrinolytic capacity of patients with acute myocardial infarction (AMI) is known to be impaired. The primary regulatory element of the fibrinolytic system is plasminogen activator inhibitor (PAI). It has been previously observed that there are 2 peaks in the plasma PAI level of AMI patients at 4h and 16h after thrombolytic therapy with recombinant tissue plasminogen activator (rtPA). Lanoteplase/SUN9216 is a mutant tPA with a biological half-life longer than that of rtPA. Thrombolytic therapy with mutant tPA or rtPA was carried out consecutively in 21 patients with AMI (8 patients as the mutant tPA group, and 13 patients as the rtPA group). The recanalization time of the mutant tPA group was significantly faster than that of the rtPA group (16.1 +/- 3.9 min vs 39.6 +/- 4.8 min, p<0.01). The PAI activity at 4h after the initiation of thrombolysis was significantly lower in the mutant tPA group than in the rtPA group (8.74 +/- 5.46IU/L vs 26.74 +/- 3.35 IU/L, p<0.01). There was a one mild peak in serial plasma PAI activity levels 24h after the initiation of thrombolysis. The results suggest that thrombolytic therapy with mutant tPA reduced the impairment of fibrinolytic capacity. The mutant tPA gives faster recanalization and lower PAI activity after successful thrombolysis, compared with rtPA.

Aged↗

PubMed1998

Characterization of truncated human mannan-binding protein (MBP) expressed in Escherichia coli.

Mannan-binding protein (MBP) is a calcium-dependent mammalian serum lectin important in first-line host defense. MBP belongs to the collectin family, which is characterized by an NH2-terminal cysteine-rich domain, a collagen-like domain, a neck domain, and a carbohydrate recognition domain (CRD). We have expressed a recombinant human MBP, consisting of the short collagen region (two repeats of Gly-Xaa-Yaa amino acid sequences), the neck domain, and the CRD, in Escherichia coli. The truncated MBP was capable of forming trimers by association of the neck domain and could bind sugar with a specificity similar to that of the native form. Results of hemagglutination inhibition (HI) assay of influenza A virus showed that the truncated MBP inhibited hemagglutination less strongly, although the native MBP induced the HI phenomenon. These results suggest that an oligomeric structure is an advantage for MBP to have full biological activity against influenza A virus.

Carrier Proteins↗

PubMed1998

[Reproductive and developmental toxicity study of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na (1). Fertility study in rats].

Fertility study of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na), a novel neutrophil elastase inhibitor, was conducted in Sprague-Dawley (SD) rats. ONO-5046.Na was administered intravenously at doses of 18.75, 37.5 and 75 mg/kg/day to male rats from 64 prior to mating, through the mating period and until necropsy, and to female rats from 15 days prior to mating until Day 7 of gestation, in order to examine its effects on fertility and reproductive performance of males and females and the development of their fetuses. There were no changes attributable to ONO-5046.Na in general signs, body weight, food consumption or autopsy findings in males and females. No drug-related changes were observed in estrous cycles, copulation and fertility indices in males and females. Pituitary weight of dams was decreased in each of the ONO-5046.Na treated groups, but no histopathological changes were observed in the pituitary. In the cesarean section findings in dams, ONO-5046.Na had no effects on the number of corpola lutea, the number of live fetuses, the implantation ratio, the resorbed and dead fetus ratio, fetal or placental weight, or the incidences of external, skeletal or visceral anomalies of the fetuses. From these results, it is considered that the NOAEL of ONO-5046.Na is 75 mg/kg/day for general and reproductive toxicity in males and females and for developmental toxicity in their fetuses.

Animals↗

PubMed1998

[Reproductive and developmental toxicity study of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na) (2). Study for effects on pre- and postnatal development in rats, including maternal function].

Prenatal and postnatal toxicity of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na), a novel inhibitor of human neutrophil elastase, was studied in Sprague-Dawley (SD) rats. ONO-5046.Na was injected intravenously at doses of 0, 18.75, 37.5 and 75 mg/kg/day to pregnant rats from day 7 of pregnancy to day 20 after delivery. All pregnant rats were allowed to deliver naturally for postnatal examination of their offspring. No adverse effects on dams were observed in clinical signs, body weight change, food consumption, pregnant, delivery or lactating performances. ONO-5046.Na did not affect the postnatal development of offspring, including birth index, survival index, physical and functional development, motor activity, emotionality, learning ability and reproductive performance. From these results, it is considered that the NOAEL of ONO-5046.Na is 75 mg/kg/day for dams and their offspring.

Animals↗

PubMed1998

[Reproductive and developmental toxicity study of sodium N-[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino] benzoyl] aminoacetate tetrahydrate (ONO-5046.Na) (3). Teratogenicity study in rabbits].

Teratogenicity of sodium N[2-[4-(2,2-dimethylpropionyloxy) phenylsulfonylamino]benzoyl] aminoacetate tetrahydrate (ONO-5046.Na), a novel inhibitor of human neutrophil elastase, was studied. ONO-5046.Na was injected intravenously at doses of 0, 7.5, 15 and 30 mg/kg/day to pregnant Kbl: NZW rabbits from day 6 to day 18 of pregnancy. All female rabbits were sacrificed on day 29 of pregnancy and their fetuses were examined. There were no clinical signs or death attributable to ONO-5046.Na. One dam in the control group and 3 dams in the 30 mg/kg/day group aborted. Body weight gain in the 15 and 20 mg/kg/day groups and food intake in the 30 mg/kg/day group were decreased during the administration period. These changes had recovered by the end of the study. Kidney weight was increased in the 30 mg/kg/day group. There were no effects of ONO-5046.Na in necropsy findings at cesarean section in dams at any dose levels. Developmental toxicity of ONO-5046.Na was not found at any dose levels. From these results, it is considered that the NOAEL of ONO-5046.Na is 7.5 mg/kg/day for pregnant animals and 30 mg/kg/day for fetuses.

Animals↗

PubMed1998

Linear O2 use-pressure-volume area relation from curved end-systolic pressure-volume relation of the blood-perfused rat left ventricle.

We measured rat left ventricular pressure, volume, and oxygen consumption ( = arteriovenous oxygen content differencexcoronary flow) to establish a new evaluation of its mechanoenergetics in the whole heart preparation by using the cross-circulation method. We obtained a curved end-systolic pressure-volume relation in contrast to a linear end-systolic pressure-volume relation in dogs, rabbits, and humans. However, we obtained a linear oxygen consumption per beat (VO2)-systolic pressure-volume area (PVA, a measure of left ventricular total mechanical energy per beat) relation as in other species. Thus PVA can be a good index for assessing rat left ventricular mechanoenergetics. The VO2 intercept and slope of the linear VO2-PVA relation correspond to those in other species. Intracoronary calcium elevated the curved end-systolic pressure-volume relation and significantly increased PVA at 0.15 ml/g of left ventricular end-diastolic volume (PVA0.15) by 50%. Calcium also significantly increased the VO2 intercept of the VO2-PVA relation by 30% without a change in its slope. We conclude that the rat left ventricular end-systolic pressure-volume relation is curved, but the VO2-PVA relation is linear, and that the VO2 intercept is mainly composed of PVA-independent VO2, presumably VO2 for Ca2+ handling in the excitation-contraction coupling and basal metabolism. Therefore we propose PVA at an appropriate left ventricular volume and the VO2 intercept as good rat left ventricular mechanoenergetic indexes despite the nonlinearity of the end-systolic pressure-volume relation.

Animals↗