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M Shimamura

Publications and source records attributed to M Shimamura.

At least 91 records · Page 5Linked to original sources
PubMed1993

Effects of seed saponins of Thea sinensis L. (Ryokucha saponin) on alcohol absorption and metabolism.

We evaluated the effects of the seed saponins of Thea sinensis L. on alcohol absorption and metabolism in rats and mice. An ethanolic extract from the seeds of T. sinensis was orally administered to the rats 1 hr before or 0.5 hr after administration of ethanol (2 g/kg), and the blood ethanol assayed 0.5, 1, 2, 3, and 4 hr after ethanol administration. The ethanol level decreased after both pre- and post-administration of the extract. The extract was further purified to obtain a saponin fraction which was orally administered to mice 1 hr before ethanol administration. Blood, liver, and stomach were obtained 0, 1, 3, and 6 hr after ethanol administration, and the ethanol, acetaldehyde, acetate, and acetone concentrations in each specimen were measured by head space gas chromatography. The saponin fraction decreased the ethanol levels in the blood and liver but increased that in the stomach five-fold over the control level, suggesting inhibition of alcohol absorption. The ethanol disappearance time from the blood was shortened, suggesting the promotion of alcohol disappearance. The acetate and acetone levels were unaffected. However, the acetaldehyde level decreased in the blood, liver, and stomach. The decreases in the ethanol and acetaldehyde levels in the liver suggested the protective effects of the seed saponins on the liver. The saponins did not directly inhibit hepatic alcohol dehydrogenase activity. The seed saponins of T. sinensis seem to suppress alcohol absorption by slowing gastric emptying and by inhibiting absorption across the cell membranes of the digestive tract.

Acetaldehyde↗
PubMed1992

A novel ganglioside expressed by mouse hematopoietic cell lines.

Mouse progenitor T cell-derived cell lines were established by fusion of cells of hematopoietic organs such as bone marrow and fetal liver with T lymphoma (BW5147) to determine their characteristic cell-surface components. The hybridomas with the phenotype of Thy-1+, CD3-, CD4-, CD8- and expression of T cell receptor gene mRNA (BM216 and FL339) were selected for progenitor T cell-derived cell lines, and their ganglioside compositions were studied. A ganglioside component with a mobility slightly faster than that of bovine brain GD1a on high-performance thin-layer chromatography was found in the cell extracts of these cell lines as one of the most abundant components and was absent in the extract of the parental cell line (BW5147). The structure of the ganglioside was determined to be: NeuAc alpha-Gal beta-Gal beta-Gal alpha-Gal beta-Glc beta-ceramide. Gangliosides with such a sequence have never been found before, suggesting the possibility that the ganglioside is expressed as a surface marker of the cells in hematopoietic organs committed to a specific cell lineage, presumably to T cell lineage. cells in hematopoietic organs committed to a specific

Animals↗
PubMed1992

Presence of murine fetal liver cells capable of being induced to differentiate in vitro into T cell receptor-positive cells.

Mouse fetal liver cells were analyzed for the surface expression of T cell markers. Fetal liver cells prepared from mouse embryos at 14.5 days of gestation contained a small number of CD4+ cells (1.4%), but virtually no cells positive for any other T cell markers such as CD8, CD3 and T cell receptor (TcR). When a fetal liver cell suspension prepared from BALB/c(male) x AKR(female) F1 embryos at 14.5 days of gestation was cultured in medium supplemented with culture supernatants of both WEHI-3 and concanavalin A-stimulated rat spleen cells, TcR alpha beta+ and CD4+ cells were generated, whereas CD8+ and TcR gamma delta+ cells were hardly detectable. Most of TcR alpha beta+ and CD4+ cells were H-2d+, thus clearly showing their fetal origin. Treatment with anti-CD4, anti-CD3 or anti-TcR alpha beta antibodies plus complement or electronic sorting to remove cells expressing these markers failed to inhibit the generation of T cell marker-positive cells following culture in vitro. On the other hand, depletion of Thy-1.2+ cells reduced their generation. These findings indicate the presence of some progenitor T cells in fetal liver with the Thy-1+, CD3-, CD4-, CD8-, TcR- phenotype, which can be induced to differentiate into TcR alpha beta+ cells in the presence of specific humoral supplements without the influence of the thymus.

Animals↗
PubMed1992

Role of mucosal prostaglandins in vagally-mediated adaptive cytoprotection in the rat.

This study was designed to investigate whether vagal innervation and mucosal prostaglandins (PGs) participate in gastric adaptive cytoprotection. Rats were divided into three groups; sham operation (control), truncal vagotomy or splanchnicotomy. In the first experiment, 100% ethanol (EtOH) was orally administered 15 min after pretreatment with 20% EtOH to all 3 groups. One hour later, the gastric mucosa was examined macroscopically. In a second experiment, the mucosal PG contents 15 min after administration of either 20% EtOH or saline were measured by high performance liquid chromatography. In truncal vagotomized rats, the adaptive cytoprotection caused by exposure to 20% EtOH in control and splanchnicotomized rats was not observed and an increase in hemorrhagic lesion severity was seen. In the control and splanchnicotomized rats, PGE2 contents were elevated following 20% EtHO treatment, as compared to those in the saline-treated rats. However, PGE2 contents in vagotomized rats were not altered by EtOH exposure, and were significantly lower than in the control and splanchnicotomized groups, whereas PGF2 alpha and PGD2 contents were significantly higher after EtOH administration as compared to those in saline-treated rats. These results suggest that vagal innervation is essential for adaptive cytoprotection and that the vagotomy-induced decrease in PGE2 and increases in PGF2 alpha and PGD2 following 20% EtOH administration, may be caused by a disturbance in adaptive cytoprotection.

Animals↗
PubMed1992

Effect of 15-deoxyspergualin, a microbial angiogenesis inhibitor, on the biological activities of bovine vascular endothelial cells.

We found recently that 15-deoxyspergualin, an analog of spergualin, which is an antibiotic and includes a spermidine moiety in its structure, exhibits anti-angiogenic activity. We have now carried out in vitro experiments with bovine vascular endothelial cells to determine which events occurring during angiogenesis are affected by this microbial angiogenesis inhibitor. 15-Deoxyspergualin did not inhibit the production of urokinase-type plasminogen activator (u-PA) or type IV collagenase by vascular endothelial cells. The direct inhibition of u-PA activity by 15-deoxyspergualin was not observed either. The angiostatic antibiotic neither affected the migration of vascular endothelial cells nor inhibited the endothelial cell proliferation in a two-dimensional culture system. We also examined the effect of 15-deoxyspergualin on the proliferation of endothelial cells in a three-dimensional culture system involving collagen gel, in which cell growth resembles more closely the endothelial cell proliferation during in vivo angiogenesis than that in a two-dimensional culture system without collagen gel. The antibiotic inhibited cell proliferation in a dose-dependent manner, indicating that the three-dimensional culture system is useful for finding a new angiogenesis inhibitor with a different mode of action from those of angiogenesis inhibitors found by using a two-dimensional assay system; however, no cause-effect relationship has yet been established. Taken together, these results suggest the possible involvement of the inhibition of vascular endothelial cell growth by 15-deoxyspergualin in its angiogenesis-inhibitory effect. 15-Deoxyspergualin appears to be a promising candidate as an angiogenesis inhibitor for controlling aberrant angiogenic responses occurring in different states, including tumor development.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Okadaic acid is a potent angiogenesis inducer.

Okadaic acid, which is a non-12-O-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoter and an inhibitor of protein phosphatases 1 and 2A, induced angiogenesis in the chorioallantoic membrane of the chick embryo. Its potent angiogenic activity was dose-dependent. The minimum effective dose was 5 fmol/egg and the effective dose for 50% induction was 90 fmol/egg. These results indicated that okadaic acid exhibits angiogenic activity one order of magnitude stronger than that of TPA (reported previously). Moreover, the time-course of angiogenesis induction by okadaic acid was much slower than that by TPA. The difference is consistent with the time-courses of other biochemical and biological activities and also various gene expressions induced by okadaic acid and TPA, indicating that the difference in the time-course is associated with their mechanisms of action. We conclude that okadaic acid induces angiogenesis through a different pathway than does TPA, indicating the existence of a new mechanism of angiogenesis induction.

Animals↗
PubMed1992

Inhibition of angiogenesis by staurosporine, a potent protein kinase inhibitor.

The effect of staurosporine, a potent inhibitor of protein kinases, on embryonic angiogenesis was studied in an in vivo assay system involving chorioallantoic membranes of growing chick embryo. Staurosporine inhibited embryonic angiogenesis in a dose-related manner, the ID50 value being 71 pmol/egg. Staurosporine dose-dependently suppressed the proliferation of vascular endothelial cells, an important event involved in the angiogenesis process. The IC50 value was 0.88 nM. In contrast, staurosporine did not affect the migration of vascular endothelial cells. These results suggest that staurosporine affected embryonic angiogenesis probably by inhibiting endothelial cell proliferation. In addition, these results might support the notion that certain protein kinase(s) could be implicated in induction of angiogenesis and also that staurosporine would be a useful compound for studying a mode of action of angiogenesis occurring in various diseases, including tumor development.

Alkaloids↗
PubMed1992

Haematopoietic cell lines capable of colonizing the thymus following in vivo transfer expressed T-cell receptor gamma-gene immature mRNA.

To clarify the mechanism by which progenitor T (pro-T) cells recognize and enter the thymus, an attempt was made to produce haematopoietic cell lines by the fusion of BALB/c nude mouse bone marrow or foetal liver cells (gestation 14 and 15 days) with AKR thymoma BW5147, thereby immortalizing cells with potency to colonize the thymus, a characteristic of pro-T cells rarely found in adult bone marrow or foetal liver. The hybridomas thus produced were classified according to the phenotype of surface markers, T-cell receptor (TcR) gene configuration and expression. All hybridomas were negative in the surface expression of T-cell markers such as TcR alpha beta, TcR gamma delta, CD3, CD4 and CD8. They had TcR beta-, gamma- and delta-genes, each with a different status with respect to configuration and transcription. Some possessed partially rearranged TcR genes and others expressed immature TcR mRNA. The cell lines were examined for their capacity to colonize the thymus following intravenous injection into recipient mice. It was found that the cells with capacity of colonizing the thymus expressed immature TcR delta mRNA, while the cell lines lacking TcR delta-genes did not home to the thymus. These findings imply that the potency for migrating to thymus is closely associated with the particular stage of prethymic cell differentiation which could be estimated by the analysis of TcR genes, and that some cell lines with the expression of TcR delta-gene mRNA and the ability to colonize the thymus are derived from pro-T cells.

Animals↗
PubMed1991

Eponemycin, a novel antibiotic, is a highly powerful angiogenesis inhibitor.

Eponemycin, a novel antibiotic, was examined as to its anti-angiogenic activity in an in vivo assay system involving chorioallantoic membranes (CAMs) of growing chick embryos. Eponemycin powerfully inhibited angiogenesis in the CAMs. This powerful inhibition was dose-dependent, the inhibitory activity becoming detectable at a dose of 7.5 fmol/egg and the ID50 value being 250 fmol/egg, suggesting that eponemycin exhibits more potent anti-angiogenic activity than Ch 55, a synthetic retinoid, which had been the strongest angiogenesis inhibitor identified so far. To determine which event(s) in the angiogenesis process was affected by eponemycin, experiments were conducted using systems involving cultured vascular endothelial cells. Eponemycin effectively inhibited both the proliferation and migration of endothelial cells, indicating that the antibiotic affected these two important events during angiogenesis, resulting in effective inhibition of angiogenesis. These results strongly suggest that eponemycin could be a promising candidate as an angiogenesis inhibitor for the control of aberrant angiogenesis occurring in different diseases such as tumor development and diabetic retinopathy.

Allantois↗
PubMed1991

The retarded rate of acid-catalyzed solvolysis of glycoside bonds between reducing-end glucose residue and ceramide in glycosphingolipids compared with that of glycoside bonds between hexopyranosides.

Rates of acid-catalyzed solvolysis of glycoside bonds in glycosphingolipids were compared to establish a basis for conducting saccharide analysis. Permethylated globotetraosylceramide and asialogangliotriaosylceramide as model compounds for methylation and sugar composition analysis, respectively, were solvolyzed under acidic conditions and the sugar components thus obtained were determined at specified times by gas liquid chromatography, after they had been derivatized. Reducing-end glucose residues in both compounds were liberated more slowly than other sugar residues. Glycoside bonds between reducing-end glucose and ceramide in glycosphingolipids would thus appear to be more resistant towards acid-catalysed solvolysis than other glycoside bonds between hexopyranosides.

Acids↗
PubMed1991

Analysis of the forelimb crossed extension reflex in thalamic cats during stepping.

Forelimb crossed extension reflexes were examined in 22 thalamic cats. These reflexes were elicited either by backward passive movement or by repetitive electrical stimulation of cutaneous and joint afferent nerves in the contralateral forelimb. Single stimulation of the superficial radial nerve evoked two types of reflex responses--early (ER) and late (LR)--from the triceps brachii muscle on the contralateral side. The latencies were about 7 and 16-25 ms, corresponding to the propriospinal (PSR) and spino-bulbo-spinal (SBS) reflexes of the ipsilateral flexor, respectively. Repetitive stimulation of the superficial radial nerve evoked the LR but not the ER. The crossed extension reflex and LR were abolished by lesions of the dorsolateral funiculus of the cervical cord on the side opposite to the recording. The tonic EMG activity, crossed extension reflex and LR in the extensor on the side of lesions were abolished by lesions of the ventrolateral funiculus of the cervical cord. During forelimb stepping, the amplitudes of both ER and LR fluctuated depending on the phase of the step cycle. The ER appeared during a narrow period in the early phase of the stance, whereas the LR was observed during a wide period from the middle of the swing to the middle of the stance. Both responses were absent from the middle of the stance to the middle of the swing. These observations suggest that forelimb crossed extension reflexes involve both spinal and supraspinal (SBS) loop mechanisms, and that these are utilized during stepping, with the latter mechanism in particular playing an important part in the extension phase of the forelimb forward movement.

Afferent Pathways↗
PubMed1991

Enkephalin-degrading aminopeptidase in the longitudinal muscle layer of guinea pig small intestine: its properties and action on neuropeptides.

A membrane-bound enkephalin-degrading aminopeptidase was purified from the longitudinal muscle layer of the guinea pig small intestine by four steps of column chromatography using L-tyrosine beta-naphthylamide. The molecular weight of the enzyme was estimated to be 105,000 by gel filtration. The maximum activity was observed between pH 6.5 and 7.0. The Km value for leucine-enkephalin was 137 microM. The aminopeptidase activity toward aminoacyl beta-naphthylamide substrates was restricted to basic, neutral, and aromatic aminoacyl derivatives. No action was detected on acidic amino acid and proline derivatives. The enzyme was potently inhibited by the aminopeptidase inhibitors actinonin, amastatin, and bestatin, and bioactive peptides such as angiotensin III, substance P, and Met-Lys-bradykinin. The enzyme activity was also inhibited by the antibody against the purified serum enkephalin-degrading aminopeptidase of guinea pig at concentrations similar to those at which activity was observed toward serum enkephalin-degrading aminopeptidase and renal aminopeptidase M. The enzyme rapidly hydrolyzed Leu-enkephalin and Met-enkephalin with the sequential removal of the N-terminal amino acid residues. The enzyme also hydrolyzed two enkephalin derivatives, angiotensin III and neurokinin A. However, neurotensin, substance P, and bradykinin were not cleaved. These properties indicated that the membrane-bound enkephalin-degrading aminopeptidase in the longitudinal muscle layer of the small intestine is similar to the serum enkephalin-degrading aminopeptidase and resembles aminopeptidase M. It is therefore suggested to play an important role in the metabolism of some bioactive peptides including enkephalin in peripheral nervous systems in vivo.

Aminopeptidases↗
PubMed1991

Antitumor effect of 22-oxa-1 alpha,25-dihydroxyvitamin D3, a potent angiogenesis inhibitor, on rat mammary tumors induced by 7,12-dimethylbenz[a]anthracene.

The effect of 22-oxa-1 alpha,25-dihydroxyvitamin D3 (22-oxa-1,25(OH)2D3) on the growth of autochthonous rat mammary tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) was examined on the basis of our previous finding that this synthetic vitamin D3 analog has a potent angiogenesis inhibitory effect. Two doses of 22-oxa-1,25(OH)2D3, 0.1 and 1 microgram/kg of body weight, due to the limited amount of the compound available, were used. The daily administration of 22-oxa-1,25(OH)2D3 at the dose of 1 microgram/kg/day resulted in significant inhibition of the growth of these mammary tumors at 1, 2 and 3 weeks after the administration of this agent, although the agent caused little or no regression of the tumors. After daily administration for 3 weeks, a significant antitumor effect was also observed in the group treated with 0.1 microgram/kg/day. Treatment with 22-oxa-1,25(OH)2D3 did not affect the serum calcium levels in the treated rats. The lower dose of 22-oxa-1,25(OH)2D3 neither affected weight gain nor caused a decrease in body weight, while the higher dose, although having some effect on weight gain, did not induce a decrease in body weight. There were no significant differences in the weights of adrenals, uteri and ovaries between the treated groups and controls. These results suggest that 22-oxa-1,25(OH)2D3 has a significant growth inhibitory effect on DMBA-induced autochthonous mammary tumors in rats, without producing severe side effects, including hypercalcemic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1991

Bacteremia from transurethral prostatic resection under prophylactic use of antibiotics.

We studied the incidence of the postoperative bacteremia developing in 44 patients undergoing transurethral resection of the prostate under prophylactic use of antibiotics. In 15 of the patients, postoperative endotoxinemia was also investigated. Postoperative bacteremia was found in 10 (22.7%) of the patients, in only one of whom septicemia developed. The incidence of bacteremia was not influenced by the kind of antimicrobial agent administered prophylactically, but was significantly higher in the patients with preoperative urinary tract infection or prostatitis on histological examination of resected prostatic tissue (p less than 0.01). Concerning species isolated from the blood, gram-positive cocci were isolated more frequently than gram-negative bacteria, and Staphylococcus epidermidis was the most common species. In 7 (70%) of the bacteremia patients an identical species was isolated from preoperative urine cultures. In the patients with bacteremia, significant increases in white blood cell count and maximal body temperature were found within 3 hours after the procedure as compared to before the procedure. To lower the postoperative bacteremic rate, appropriate and adequate antimicrobial agents must be used preoperatively in patients with infection of the genitourinary tract. As to blood endotoxin, the endotoxin levels in the patients with postoperative fever did not significantly differ from those of the patients without this complication.

Aged↗
PubMed1991

Concentrations of blood and urine ethanol, acetaldehyde, acetate and acetone during experimental hangover in volunteers.

Blood and urine samples were analyzed for ethanol, acetaldehyde, acetate and acetone during experimental hangover in 6 healthy male volunteers (A, B, C, D, E, F). They drank freely for some 4 hr. In flushers (A, F) at 9 hr after ingestion (ethanol: 92 g, 1.2 g/kg and 1.3 g/kg), acetaldehyde levels were low in the blood, but high in the urine (37 microM, 45 microM). Heavy drinkers, non-flushers of B (ethanol: 176 g, 2.5 g/kg), C (157 g, 2.4 g/kg) and E (182 g, 2.9 g/kg) had a slightly high [lactate]/[pyruvate] ratio and 3-hydroxybutyrate in the blood at 11 hr after alcohol ingestion. Blood ethanol levels were dose dependent and blood acetaldehyde in B and C had a slightly high 6.3 microM and 8.0 microM 9 hr later, respectively. B, C and E had a high urine acetone concentration (100 microM over) in hangover. In C, in particular, urine acetate and acetone levels were unusually high. The ratio in blood (urine) among alcohol metabolites at 9 hr after drinking was approximately ethanol 1000 (1000): acetaldehyde 0.2-1.0 (0.1-5.9): acetate 36-163 (22-1554): acetone 1-11 (3-47).

Acetaldehyde↗
PubMed1990

Crossed forelimb extension produced in thalamic cats by injection of putative transmitter substances into the paralemniscal pontine reticular formation.

To analyze the descending pathways of the paralemniscal pontine reticular formation (PLRF), a technique was used for the selective activation of cell bodies by localized injection of putative neurotransmitters in the PLRF. When a small amount (less than 0.1 microliter) of 0.1 M glutamate was injected into the PLRF unilaterally in thalamic cats, the forelimb contralateral (c-forelimb) to the injection was extended, and occasionally the ipsilateral forelimb was flexed. These responses were similar to those obtained by electrical stimulation of the PLRF, but were relatively weaker. Unit spikes of PLRF neurons were increased in frequency following administration of glutamate. The latent periods and durations of increases in spike frequency varied depending on the concentration and quantity of the glutamate solution, and were roughly similar to those of the extensor EMG in the c-forelimb. Since the firing of PLRF neurons preceded the EMG with 11 ms latency, the unit spike of PLRF neurons could be used as a triggering signal to observe a spike triggered averaged EMG response in the extensor muscle of the c-forelimb. Results similar to those with glutamate were observed upon administration of quisqualate, kainate and aspartate. The most effective compound was quisqualate. Application to the PLRF of 1-naphthylacetyl spermine (1-NA-Spm), an analogue of the natural spider toxin JSTX-3 and an antagonist of glutamate, suppressed both the PLRF neuron activity and the extensor EMG of the c-forelimb. These observations suggest that extensor muscles of the forelimb are excited by the contralateral PLRF, perhaps via the crossed reticulospinal tract from the PLRF. PLRF neurons may be activated by glutamate (quisqualate) receptors.

Animals↗
PubMed1990

A novel angiogenic inhibitor derived from Japanese shark cartilage (I). Extraction and estimation of inhibitory activities toward tumor and embryonic angiogenesis.

Guanidine extraction and crude fractionation of Japanese shark cartilage by ultrafiltration on a molecular weight basis were conducted and the antiangiogenic activities were assayed as to the inhibitions of tumor and embryonic angiogenesis. Significant inhibition of angiogenesis was found, and there was a linear relationship between the results of the two assays. The inhibitory activities were concentrated in the fraction in the molecular weight range of 103 to 104, and were resistant to heat treatment.

Animals↗