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Biomedical subjects

K Fujimoto

Publications and source records attributed to K Fujimoto.

At least 541 records · Page 30Linked to original sources
PubMed1993

Paradoxical GABAergic facilitation on seizure development observed from bicuculline-induced effects on visual cortical kindling at short interstimulus intervals in chronically prepared rabbits.

To investigate the influence of GABAergic function on seizure development, the effects of bicuculline, a GABAa receptor antagonist, on visual cortical and hippocampal kindling were examined in chronically prepared rabbits. Kindling-inducing stimulations were repeated at 5-min intervals. The changes in afterdischarge (AD) durations were compared before and 30 min after a low (2 mg/kg) and high dose (5 mg/kg) i.p. injection of bicuculline solution. In the visual cortical kindling group, the AD durations were markedly shortened after the low dose bicuculline injection, while bicuculline produced a prolongation of the AD durations in the visual cortical with the high dose injection and hippocampal kindling groups. The low dose bicuculline-induced inhibition of visual cortical kindling suggests facilitative GABAergic action on seizure development, while the drug-induced enhancement in the other groups reflects the well-known inhibitory GABAergic action.

Animals↗
PubMed1993

Effects of physostigmine and some nitric oxide-cyclic GMP-related compounds on muscarinic receptor-mediated autoinhibition of hippocampal acetylcholine release.

We have investigated the effects of (a) the cholinesterase inhibitor physostigmine and (b) drugs that are known to change intracellular cyclic GMP levels on the autoinhibition of acetylcholine release from rat hippocampal slices. Autoinhibition was triggered by submaximal electrical stimulation in both the absence and presence of physostigmine. The results obtained indicate that an unusual increase in the extracellular acetylcholine content, such as that induced by cholinesterase inhibition, is not essential for autoinhibition triggering. Dibutyryl cyclic GMP reduced significantly the stimulation-evoked acetylcholine release in the presence, but not in the absence, of atropine. Neither sodium nitroprusside nor glyceryl trinitrate exerted a dibutyryl cyclic GMP-like effect. NG-Nitro-L-arginine did not lessen the autoinhibition. These results indicate that an increase in the intracellular cyclic GMP level reduces acetylcholine release, and that the muscarinic receptor stimulation-nitric oxide synthesis-(soluble) guanylyl cyclase activation pathway is not involved in the cholinergic autoinhibition process.

Acetylcholine↗
PubMed1993

Cloning, sequence, and expression of a chitinase gene from a marine bacterium, Altermonas sp. strain O-7.

The gene encoding an extracellular chitinase from marine Alteromonas sp. strain O-7 was cloned in Escherichia coli JM109 by using pUC18. The chitinase produced was not secreted into the growth medium but accumulated in the periplasmic space. A chitinase-positive clone of E. coli produced two chitinases with different molecular weights from a single chitinase gene. These proteins showed almost the same enzymatic properties as the native chitinase of Alteromonas sp. strain O-7. The N-terminal sequences of the two enzymes were identical. The nucleotide sequence of the 3,394-bp SphI-HindIII fragment that included the chitinase gene was determined. A single open reading frame was found to encode a protein consisting of 820 amino acids with a molecular weight of 87,341. A putative ribosome-binding site, promoter, and signal sequence were identified. The deduced amino acid sequence of the cloned chitinase showed sequence homology with chitinases A (33.4%) and B (15.3%) from Serratia marcescens. Regardless of origin, the enzymes of the two bacteria isolated from marine and terrestrial environments had high homology, suggesting that these organisms evolved from a common ancestor.

Amino Acid Sequence↗
PubMed1993

Effect of vagotomy on ornithine decarboxylase activity in rat duodenal mucosa.

The aim of this study was to determine whether the circadian rhythm of ornithine decarboxylase (ODC) activity in rat small intestine is controlled by factors other than luminal nutrients. ODC activity in duodenal and jejunal mucosa of rats fed ad libitum was measured at four time points (0500, 1100, 1700, 2300 h; light period: 0800-2000 h). ODC activity in the jejunum increased in the dark period, which is when rats normally eat. In contrast, ODC activity in the duodenum began to increase at 1700 h, which is when rats do not normally eat, as indicated by the recorded feeding pattern. The increase in ODC activity in the duodenum at 1700 h, but not at other time points, was abolished by subdiaphragmatic vagotomy, whereas vagotomy had no effect on the feeding pattern of rats. Subdiaphragmatic vagotomy had no effect on ODC activity in the jejunum. ODC activity in the duodenum increased following glycoprivation of the central nervous system induced by infusion of 2-deoxyglucose into the third cerebroventricle. These results indicate that the increase in duodenal ODC activity at 1700 h is due to a signal from the upper brain structure through the vagal nerve and not to luminal nutrient factors.

Animals↗
PubMed1993

Preparation of peptide-carrying microspheres with bioactivity on platelets.

A tetrapeptide RGDS (Arg-Gly-Asp-Ser), which is one of the active sites of cell adhesive proteins, was synthesized according to the solution method and covalently coupled onto monodisperse microspheres. The biospecific activity of the RGDS-carrying microspheres was investigated by measuring the stimulatory effect of the microspheres on platelets. Large and tightly packed platelet aggregation accompanied with drastic ATP release was induced by the RGDS-carrying microspheres. It was confirmed that the specific platelet aggregation was attributed to the activity of the immobilized RGDS by comparison with those induced by other microspheres.

Acrylamides↗
PubMed1993

Mechanism of cytoplasmic calcium changes in platelets in contact with polystyrene and poly(acrylamide-co-methacrylic acid) surfaces.

Changes in cytoplasmic free calcium levels ([Ca2+]i) in platelets in contact with polystyrene (PSt) and poly(acrylamide-co-methacrylic acid) (PAAmMAc) particles were evaluated and results were compared with those from two representative biological calcium agonists; thrombin and calcium ionophore A23187. PSt particles stimulated a steep increase in cytoplasmic calcium levels in platelets as much as thrombin and A23187. Serratia protease-treated platelets showed a steep increase in [Ca2+]i by PSt particles, suggesting that PSt surfaces can initiate platelet activation independent of a glycoprotein Ib (GPIb)-mediated pathway. By contrast, dibucaine-treated platelets showed little increase in [Ca2+]i by PSt particles, indicating that microfilament assembly, including binding of GPIb with actin binding protein, should be required for platelet activation in contact with PSt surfaces. PAAmMAc particles induced little increase in cytoplasmic calcium levels in platelets. However, PAAmMAc particle-treated platelets demonstrated little response to thrombin in terms of an increase in [Ca2+]i and ATP release, suggesting the possibility that PAAmMAc surfaces may regulate [Ca2+]i by influencing platelet metabolism. Furthermore, sodium azide-treated platelets showed an increase in [Ca2+]i in platelets when contacting PAAmMAc particles, supporting the suggestion that PAAmMAc surfaces could regulate platelet functions. Fluorescence polarization measurements using 1,6-diphenyl-1,3,5-hexatriene-loaded platelets revealed that PAAmMAc particles increased membrane fluidity in platelets, which may be due to physicochemical interaction with PAAmMAc surfaces.

Acrylic Resins↗
PubMed1993

Suppression of food intake by apolipoprotein A-IV is mediated through the central nervous system in rats.

The aim of this experiment was to investigate whether the anorectic effect of apolipoprotein A-IV (apo A-IV) after lipid feeding is mediated via the central nervous system. Infusion of 0.5 micrograms of apo A-IV into the third ventricle failed to suppress food intake. Higher doses (1 micrograms or higher) of apo A-IV infused into the third ventricle inhibited food intake in a dose-dependent manner. In contrast, when apo A-I was infused into the third ventricle it had no effect on food intake. To further test the hypothesis that apo A-IV is an important factor controlling food intake, we administered goat anti-rat apo A-IV serum into the third ventricle of rats that were allowed food and water and lib. In all rats tested, this treatment resulted in enhanced food intake. In contrast, infusion of goat anti-rat apo A-IV serum failed to elicit such a response. Lastly, we determined the apo A-IV concentration in plasma and cerebrospinal fluid before and during active lipid absorption. Apo A-IV concentration in cerebrospinal fluid was about 1/20 that of plasma. Both serum and cerebrospinal fluid apo A-IV increased markedly as a result of feeding of lipid. In conclusion, we propose that apo A-IV may act centrally to control food intake.

Animals↗
PubMed1993

Novel monoclonal antibodies specific for human cardiac myosin light-chain 1: useful tools for analysis of normal and pathological hearts.

To investigate the developmental, physiological and pathophysiological roles of human cardiac myosin light-chain 1 (LC1s), we developed two novel monoclonal antibodies (KA1 and KB1) against human cardiac LC1s and examined LC1s in normal and pathological hearts immunohistochemically. KA1 and KB1 were specific only for atrial LC1 (ALC1) and for both ALC1 and ventricular LC1 (VLC1), respectively, in human hearts. Among human tissues tested, including skeletal muscle, vascular smooth muscle, and liver, KA1 did not crossreact with proteins in any other tissues than atria, whereas KB1 crossreacted with the slow-type LC1 of skeletal muscle. Among adult mammalian hearts of several other species including pig, dog, hamster, and rat, KA1 and KB1 crossreacted only with ALC1 and with both ALC1 and VLC1, respectively. ALC1 was strongly and uniformly observed in human fetal atria and ventricles and in normal adult human atria, but sporadically in normal adult human ventricles. In the overloaded ventricle (dilated cardiomyopathy), ALC1 was highly augmented but not uniform. These results suggest that the fetal VLC1 is immunohistochemically identical to the adult type of ALC1 and that ALC1 is expressed homogeneously in human fetal ventricles and sporadically in normal adult ventricles, and is re-expressed heterogeneously and in an increased amount in the overloaded ventricle.

Antibodies, Monoclonal↗
PubMed1993

Antitumor agents. II: Regio- and stereospecific syntheses of 1-beta-alkyl-1-desoxypodophyllotoxin derivatives and biological activity.

1-beta-Alkyl derivatives of 1-desoxypodophyllotoxin were synthesized, and their cytotoxicity and inhibitory effects on DNA topoisomerase II (Topo-II) and tubulin polymerization were examined. The reaction of epipodophyllotoxin derivatives (1a-c) with trimethylallylsilane in the presence of boron trifluoride etherate gave 1-beta-allylated compounds (2a-c). The regiochemistry and the beta-stereochemistry of the 1-allyl group were confirmed by comparison of the 13C-NMR spectra and NOE's (%) of 2c, podophyllotoxin (POD) and epipodophyllotoxin (1b). 1-beta-Alkyl-1-desoxypodophyllotoxin derivatives (3-8) were prepared from 2b. None of the tested compounds (3-8) showed any inhibitory effect on Topo-II. 1-beta-Propyl compound (3) and its 4'-demethyl compound (4) inhibited tubulin polymerization and the cytotoxicities of these compounds were equal to that of VP-16. 1-beta-(2,3-Dihydroxypropyl) compounds (5 and 8) and 1-beta-(2,3-diacetoxypropyl) compounds (6 and 7) showed no inhibitory effect on tubulin polymerization. Although 5 did not inhibit either Topo-II activity or tubulin polymerization, it showed a high cytotoxicity against sarcoma 180.

Animals↗
PubMed1993

Meningioangiomatosis not associated with von Recklinghausen's disease--case report.

A 7-year-old girl with meningioangiomatosis not associated with von Recklinghausen's disease is described. The radiological findings were similar to meningioma, but intraoperatively, a thin septum was found between the mass and the dura mater. Microscopically, there was significant proliferation of fibroblastic spindle-shaped cells and collagenous fibers in the subarachnoid space. Proliferated cells had penetrated into the cortical tissue along the irregularly branched blood vessels. Immunohistochemically, these penetrating perivascular cells were negative for glial fibrillary acidic protein and S-100 protein, and positive for vimentin staining. These findings suggest that the histogenesis of the spindle-shaped cells is most probably meningothelial.

Child↗
PubMed1993

Effects of endogenous and exogenous n-3 and n-6 fatty acids on microsomal synthesis of docosahexaenoic acid in vitro.

Effects of endogenous and exogenous polyunsaturated fatty acids (PUFA) on microsomal synthesis of docosahexaenoic acid (DHA) from eicosapentaenoic acid (EPA) in vitro were studied using rat livers. Liver microsomes prepared from three groups of rats which had been fed n-3/n-6 ratios of 0.01, 0.39, and 2.70, respectively, for 1 month, were incubated with [1-14C]EPA at 37 degrees C for 30 min. There were no significant differences between the formations of docosapentaenoic acid (DPA) or DHA in the groups. Liver microsomes from rats fed a diet with an n-3/n-6 ratio of 2.70 for 3 weeks were then incubated with [1-14C]EPA in the presence of unlabeled DHA or arachidonic acid (AA). The additional DHA did not have any effect. However, a significant inhibition of DHA synthesis was observed by addition of AA (EPA/AA = 5:2). These results suggest that the microsomal biosynthesis of DHA in rat liver is not susceptible to feedback inhibition.

Animals↗
PubMed1993

Evidence of docosahexaenoic acid synthesis and predominant existence of arachidonic acid in livers of fetal and neonatal crab-eating monkeys: comparisons with adults.

The microsomal synthesis of docosahexaenoic acid (DHA) from radiolabeled eicosapentaenoic acid was tested in vitro using the livers of crab-eating monkeys. The test animals included 1 fetus (embryonic day 120), 2 neonates (full-term, embryonic day 165), and 2 adults. DHA was formed equally in the liver microsomes of each animal. Neonatal livers were found to contain higher percent of arachidonic acid than adult livers in both phosphatidylcholine and phosphatidylethanolamine. DHA contents remained constant in the liver phospholipids of all test animals.

Aging↗
PubMed1993

Effects of dietary n-3 and n-6 fatty acids on liver and erythrocyte lipids in streptozotocin-induced diabetic rats.

Streptozotocin-induced diabetic and control rats were placed in one of two dietary groups and fed diets with a P/S ratio of 2.2-2.3 for 4 weeks. The n-3/n-6 ratios in the dietary groups were 0.01 (SAF group) and 2.92 (PER group). A decrease in the 20:4n-6 level, and an increase in the 18:2n-6 level were observed in the erythrocyte lipids of diabetic rats of both dietary groups, as compared with the levels in control rats. The cholesterol/lipid-P ratio in erythrocyte lipids was significantly higher in diabetic rats than in control rats in both dietary groups, while the ratio in livers was significantly lower in diabetic rats. In liver phospholipids, the differences between the polyunsaturated fatty acid contents of control and diabetic rats in the SAF group, were almost identical to those in erythrocyte lipids. However, in the PER group, a small increase in the 20:4n-6 level, besides an obvious increase in the 18:2n-6 level, was observed in diabetic rats, and n-3 fatty acid levels, especially that of 20:5n-3, were lower significantly in diabetic rats than in control rats. Plasma triglyceride and cholesterol levels in diabetic rats were higher than those in control rats in both dietary groups. The two dietary groups showed significant different triglyceride levels, but similar cholesterol levels. It is suggested that the physiological effect of 18:3n-3 is impaired in diabetes in the same manner as that of 18:2n-6 is.

Animals↗
PubMed1993

[A case of hypertrophic obstructive cardiomyopathy with marked T wave changes during the short-term].

A 72-years-old woman was admitted to our hospital for evaluation of giant negative T waves, which appeared for only two days. Chest X-p revealed a cardiomegaly of slight degree and UCG showed ASH (IVS = 21 mm). Coronary arteriography presented no significant stenosis and the left ventricle was spade-shaped. There was a pressure gradient of 65 mmHg between the aorta and the left ventricle during isoproterenol infusion. Furthermore, endomyocardial biopsy showed disarray and fibrosis to a slight degree and fatty degeneration of myocytes with contraction bands. Based on these findings, calcium blocker was administrated under the diagnosis of HOCM. One month after the initiation of this drug, negative T waves gradually became shallow and finally upright with thinning of IVS (12 mm) four month later. We swimise that this T-wave change is primarily based on myocardial hypertrophy as well as being due to the abnormality of myocardial depolarization. We presented a case of HOCM with negative T-wave change of very short duration, which was improved by calcium-blocker and beta-blocker.

Adrenergic beta-Antagonists↗
PubMed1993

[A case of sleep apnea syndrome with significant alteration of apnea index by sleep position].

An obese 37-year-old man (130% ideal body weight) was admitted to our hospital with the complaint of excessive daytime sleepiness. During all-night polysomnography, he showed predominantly obstructive sleep apnea and an apnea index (AI) of 57.5, and was diagnosed as having obstructive sleep apnea syndrome (OSAS). However, AI values calculated separately for the time in the supine position (AI-S) and in the lateral decubitus position (AI-L) were 82.4 and 5.9, respectively. Moreover, duration of apnea, lowest SaO2, and the quality of sleep were improved when sleeping in the lateral compared to the supine position. After weight reduction of 7 kg, AI in total decreased to 33.2, although AI-S was 77.3 and AI-L was 3.8. The improvement of AI in total to be due to a relative increase during sleep in the lateral position. These results suggest that in some OSAS patients, the sleep position should be taken into account in assessing the severity of the disease or in evaluating the effects of therapy. This study also suggests the efficacy of sleep position adjustment in the treatment of OSAS.

Adult↗
PubMed1993

[Arterial embalming method of the cadaver and its application to research].

Ever since 1974, the cadaver has been embalmed by the arterial embalming method, using pre-embalming fluid with blood clot disperser and cell conditioner for the removal of blood clots and drainage of blood, at the Department of Anatomy of the Kawasaki Medical School. According to this method, the cadavers are always very well fixed so that they can be used for not only anatomical dissection but also research for the vascular system by vasography, kinematics of the joint and other histologic examinations. In this report we have described our embalming procedure concretely and its application to research.

Angiography↗
PubMed1993

Chemistry of oxidative DNA strand scission.

In order to investigate the reactivity of uracilyl-5-yl radical in fixed DNA structure, photoreaction of 5-halouracil-containing oligonucleotides was investigated. It was found that photoirradiation of BrU-containing duplex DNA provided C1' oxidation product selectively at adenine residue of ABrU sequence. In contrast, photoirradiation of IU-containing DNA gave C1' and C2' oxidation products with almost no sequence preference. Sequence specific electron transfer in duplex DNA is proposed in the photoreaction of ABrU.

Adenine↗