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Biomedical subjects

M Yamazaki

Publications and source records attributed to M Yamazaki.

At least 361 records · Page 20Linked to original sources
PubMed1996

In vitro studies on a new method for islet microencapsulation using a thermoreversible gelation polymer, N-isopropylacrylamide-based copolymer.

Various materials for the semipermeable membrane for microencapsulation of islets, such as alginate complex and agarose, have been used. In this study, a thermoreversible gelation polymer, N-isopropylacrylamide based copolymer was used to make microencapsulated islets and was examined in vitro. The polymer has little or no cytotoxicity for human dermal fibroblasts. The characteristics of viscoelasticity below the soluble gel transition temperature (SGTT) and of thermoreversibility, the water soluble polymer below the SGTT (22 degrees C) becoming water insoluble upon heating, contributed to simplifying the encapsulation technique. We obtained viable islets at the center of the membrane with a thickness of approximately 20-50 microns, accounting for a 40% yield of encapsulated islets. Static glucose challenge test with microencapsulated islets revealed the insulin response to the concentration of glucose. The insulin concentrations of the culture medium in the microencapsulated islet group were the same as those in a similar free islet group up to 42 days. These results indicate that the morphological and functional stability of the new method for microencapsulation may be sufficient for it to be used for transplantation in diabetic animals.

Acrylamides↗
PubMed1996

Physicochemical properties of calcium polycarbophil, a water-absorbing polymer.

The physicochemical properties of calcium polycarbophil were examined. Calcium polycarbophil was decalcified rapidly under acidic conditions, affording polycarbophil. Polycarbophil absorbed about 10 times its own weight of water under acidic conditions, but the swelling ratio markedly increased at above pH 4.0 and reached 70 times the initial weight under neutral conditions. The swelling of polycarbophil was not affected by non-ionic osmolarity, but was affected by ionic strength, showing a decrease with increase of ionic strength. Monovalent metal ions such as sodium and potassium ions in gastrointestinal fluid did not reduce the equilibrium swelling of polycarbophil, but divalent ions such as calcium and magnesium ions did. However, calcium ion only slightly reduced the equilibrium swelling under sodium-rich conditions. The viscosity (as an indicator of fluidity) of polycarbophil was larger than that of CMC-Na at every shear rate and polymer content examined.

Acrylic Resins↗
PubMed1996

Linkage of genes essential for synthesis of a polysaccharide capsule in Sphingomonas strain S88.

Several structurally related capsular polysaccharides that are secreted by members of the genus Sphingomonas are being developed as aqueous rheological control agents for diverse industrial and food applications. They include gellan (S-60), welan (S-130), rhamsan (S-194), S-657, S-88, S-198, S-7, and NW-11. We refer to these polysaccharides as sphingans, after the genus name. This paper characterizes the first gene cluster isolated from a Sphingomonas species (S88) that is required for capsule synthesis. Overlapping DNA segments which spanned about 50 kbp of S88 DNA restored the synthesis of sphingan S-88 in capsule-negative mutants. The mutations were mapped into functional complementation groups, and the contiguous nucleotide sequence for the 29-kbp cluster was determined. The genetic complementation map and the DNA sequences were interpreted as an extended multicistronic locus containing genes essential for the assembly and secretion of polysaccharide S-88. Many of the deduced amino acid sequences were similar to gene products from other polysaccharide-secreting bacteria such as Rhizobium meliloti (succinoglycan), Xanthomonas campestris (xanthan gum), and Salmonella enterica (O antigen). The S88 locus contained a four-gene operon for the biosynthesis of dTDP-L-rhamnose, an essential precursor for the sphingans. Unexpectedly, there were also two genes for secretion of a lytic or toxin-like protein nested within the polysaccharide cluster. The conservation and linkage of genes that code for a defensive capsule and genes for secretion of an offensive lysin or toxin suggest a heretofore unknown pathogenic life history for Sphingomonas strain S88.

ATP-Binding Cassette Transporters↗
PubMed1996

Anti-tumor effects of orally administered soft-shelled turtle powder in mice.

The effects of oral administration of cryomilled powder of the soft-shelled turtle (SST powder) on solid and ascites tumor-bearing C3H/He mice were studied. The SST powder was administered orally at a dose of 100 or 500 mg/kg/d for two or four weeks, and then MH134 hepatoma cells were inoculated; oral administration was continued after inoculation. Treatment with the SST powder attenuated the increase in diameter and weight of the tumor and prolonged the survival of mice with solid tumors. However, the same treatment did not show any significant effect in mice with ascites tumor, indicating that the SST powder has no direct killing action on tumor cells. These results suggest that oral administration of the SST powder decreases the growth of solid tumors possibly by activating the host immune system.

Administration, Oral↗
PubMed1996

Stimulation of macrophage DNA synthesis by polyanionic substances through binding to the macrophage scavenger receptor.

We previously demonstrated that ligands of macrophage scavenger receptors such as acetylated low density lipoprotein (LDL), oxidized LDL and advanced glycation-end products (AGE) of the Maillard reaction induce the growth of peritoneal exudate macrophages, and that the activity of AGE is inhibited by the presence of an antibody for granulocyte/macrophage colony-stimulating factor (GM-CSF). To evaluate the suggested role of the scavenger receptor in the induction of macrophage growth, we compared the effect of various polyanionic compounds which were reported to either have or not to have competent activity for the binding of acetylated LDL to scavenger receptors on macrophage DNA synthesis. Among the polyanions exhibiting such activity, polyguanilic acid (poly G) and dextran sulfate strongly augmented macrophage DNA synthesis, although they did not increase macrophage cell number. On the other hand, polyanions which are not ligands for the scavenger receptors did not show a significant augmenting effect, suggesting that the binding of polyanions to the scavenger receptor is important but not, by itself, sufficient. The augmentation of DNA synthesis in macrophages cultured with dextran sulfate or poly G was inhibited by the co-presence of anti-GM-CSF antibody, suggesting that the reaction is mediated by GM-CSF. However, dextran sulfate did not augment the production of GM-CSF in macrophages. Therefore, GM-CSF spontaneously present in macrophages might be a prerequisite for the induction of DNA synthesis.

Animals↗
PubMed1996

Neuritogenic effect of natural iridoid compounds on PC12h cells and its possible relation to signaling protein kinases.

We examined effect of iridoid glucosides, aucubin, catalpol, geniposide and gardenoside, and their enzymic hydrolysates on neurite outgrowth of PC12h cells. Except for aucubin, these glucosides induced neurite outgrowth at 0.1 microgram/ml and above in medium after 3 d of treatment. Hydrolysates of the four glucosides all caused neuritogenesis. Geniposide hydrolysate enhanced responses of cells to carbachol and KCl-induced depolarization in terms of cytoplasmic free-calcium concentration. The aglucone of geniposide, genipin, also promoted neurite outgrowth in a dose-dependent manner (ED50 = 0.7 microM). The neuritogenic effect of genipin was partially or considerably inhibited in the presence of H-89 and genistein. All the results presented suggest that certain iridoid compounds can induce neuronal differentiation in PC12h cells through activation of components of the intracellular signal transduction pathway.

Animals↗
PubMed1996

A new series of coumarin derivatives having monoamine oxidase inhibitory activity from Monascus anka.

Monankarins A-F (1-6), a new series of pigments having conjugated pyrano-coumarin skeleton have been isolated from Monascus anka. Their structures have been elucidated by spectroscopic means and chemical modification. Monankarins A-D exhibited monoamine oxidase (MAO) inhibitory activity, while the activity was not observed in monankarins E and F or some other simple coumarins. Monankarin C (3) showed stronger inhibition of MAO-B than MAO-A in mice brain. However, the specificity was not found in mice liver MAO.

Animals↗
PubMed1996

Neurotropic components from star anise (Illicium verum Hook. fil.)

Three new neurotropic sesquiterpenoids, veranisatins A, B and C, were isolated from star anise (Illicium verum Hook. fil., Illiciaceae). Veranisatins showed convulsion and lethal toxicity in mice at a dose of 3 mg/kg (p.o.), and at lower doses they caused hypothermia. Veranisatin A and the related compound, anisatin, were tested for the other pharmacological activities such as locomotor activity and analgesic effect. Both compounds decreased the locomotion enhanced by methamphetamine at oral doses of 0.1 and 0.03 mg/kg, respectively, and demonstrated the analgesia on acetic acid-induced writhing and tail pressure pain at almost similar doses.

Acetic Acid↗
PubMed1996

Pharmacologically active components of a Peruvian medicinal plant, huanarpo (Jatropha cilliata).

From Jatropha cilliata M. Arg., a Peruvian medicinal plant, isoorientin and orientin were isolated as anxiolytic components by using the isolation guide of anti-conflict effect in mice. Several related flavonoids were also tested for this effect. Another bioassay-guided isolation using the acetic acid-induced writhing method gave a coumarin compound, fraxetin, as an analgesic principle.

Analgesics↗
PubMed1996

Comparison of the response of serum ceruloplasmin and cholesterol, and of tissue ascorbic acid, metallothionein, and nonprotein sulfhydryl in rats to the dietary level of cystine and cysteine.

The effects were compared of the addition of graded levels of L-cystine and of L-cysteine (0.3, 3, or 5%) to a 10% casein diet on several metabolic parameters in rats. The growth-promoting effect of cystine was equivalent to that of cysteine. Supplementation of these two amino acids elevated serum cholesterol, liver ascorbic acid, liver nonprotein sulfhydryl (SH) and kidney metallothionein, and reduced the activity of serum ceruloplasmin. The responses of serum cholesterol, liver nonprotein SH, and serum ceruloplasmin to cystine were greater than of those to cysteine. When the basal diet was supplemented with 0.3% of these amino acids, the elevation of liver ascorbic acid by cystine supplementation was less than that by cysteine supplementation. However, when supplemented with 5% of these amino acids, the elevation of liver ascorbic acid by cystine was greater than that by cysteine. There was no difference in the influence of cystine and cysteine on kidney metallothionein. This study demonstrates that dietary cystine and cysteine had the same influence on growth, but had a differential influence on such metabolic parameters as liver nonprotein SH, serum ceruloplasmin, serum cholesterol, and tissue ascorbic acid.

Animals↗
PubMed1996

Generalized system for plant growth analysis using infrared LED.

A computer vision system was developed to analyze plant growth. The developed system has a great advantage that various shapes of plant can be applied without any modification of software. The system consisted mainly of CCD camera, image capture board, computer, infrared LED and mirror system, and was easily set up. The infrared LED was hooked onto the plant part which was the location to be measured. Images, containing both the plant and the LED, with the different angle were simultaneously obtained using the mirror system, digitized and stored into a magneto optical diskette at a fixed interval. The centroid value of the LED was computed from the stored images and determined as the LED location. Experiments were conducted to evaluate the newly developed system by analyzing the elongation rate of Verbena bonariensis L. The results were compared to that obtained by the former non-contact analyzing system and it was found that the new system was applicable to plant growth analysis. This approach can not be substituted for the non-contact analyzing system formerly developed because it is contact type. However, this system can be applied to various plants without any modification in software, and has a potential for a wide use.

Algorithms↗
PubMed1996

Primary aldosteronism with bilateral multiple aldosterone-producing adrenal adenomas.

A 41-year-old woman developed primary aldosteronism due to bilateral multiple aldosterone-producing adenomas (APA). She was suspected to have idiopathic hyperaldosteronism (IHA) 7 years previously. Although preoperative data suggest APA and IHA was suspected in a postoperative microscopic specimen, a definite clinical diagnosis could not be made. Cytochrome P-450 and other enzymes involved in aldosterone synthesis were found in the tumor portions but not in the zona glomerulosa of attached adrenals, which histopathologically showed "paradoxical hyperplasia". This was a rare case of bilateral multiple APA, which could be differentiated from IHA by immunohistochemical analysis of adrenal steroidogenic enzymes.

Adenoma↗
PubMed1996

Treatment of large radicular cysts by modified marsupialization.

We describe the enucleation of large radicular cysts to the maximum extent, and their treatment based on the concept of marsupialization and drainage after apicoectomy. Marsupialization requires a long period for healing, imposing a burden on the patient with regard to postoperative management. Considering this, together with the difficulty involved in the clinical diagnosis of radicular cysts, curettage of the cyst wall and drainage may be more effective for facilitating the healing process than use of marsupialization alone.

Adult↗
PubMed1996

The effect of allopurinol on interstitial purine metabolism and tissue damage in skeletal muscle I-R injury.

OBJECTIVE: Many studies show that allopurinol can reduce skeletal muscle I-R (ischemia-reperfusion) injury, but the mechanism of the effect is still unclear and some studies suspect the effect. In this study, we determined whether allopurinol really reaches to reperfused muscle and reduces tissue injury by inhibiting xanthine oxidase or not. EXPERIMENTAL DESIGN: In this study, microdialysis method combined with HPLC (high performance liquid chromatography) were employed and purines, MDA (malondialdehyde), allopurinol in gracilis muscle were measured continuously in I-R injury model of canine gracilis muscle. The effect was compared between Group N (no treatment: n=8), Group P (pre-ischemic treatment: n=8) and Group R (pre-reperfusion treatment: n=8). RESULTS: Allopurinol reduced the increase of xanthine, uric acid, MDA in the muscle and CPK in blood effluent from gracilis muscle after reperfusion. Tissue protecting effect of allopurinol was more effective in group R than in group P. CONCLUSIONS: By continuous measurement of purines, allopurinol and MDA in canine gracilis muscle during 5 hr ischemia and 2 hr reperfusion, it was proved that allopurinol was delivered to reperfused skeletal muscle and reduced I-R injury by inhibiting xanthine oxidase.

Allopurinol↗
PubMed1996

[Environmental factors influencing sensitization and onset of Japanese cedar pollinosis among junior high school students].

Japanese cedar pollinosis has shown large increases especially in city areas, rather than in the rural, with increases being remarkable especially among people of young age. In order to elucidate factors for sensitization and onset of Japanese cedar pollinosis, a questionnaire survey was conducted and serum IgE antibody levels examined in junior high school students living in three different areas, i.e., city, seaside and mountainous areas in Aichi prefecture. Prevalence rate of Japanese cedar pollinosis, estimated from the number of students having both nasal or ocular allergic symptoms and positive RAST, was the 30.1% in the mountainous area with high Japanese cedar pollen count, being greater than the 15.3% in the city area and the 5.8% in the seaside area, both with low pollen counts. Among the students showing high serum mite (Dermatophagoides farinae) antibody levels, greater positive rates for sensitization to Japanese cedar or orchard grass pollens was observed, compared to mite-unsensitized students. This result suggests that sensitization to seasonal antigens may be corresponding to the capability for sensitization to the mites. Besides this finding, the analysis of replies to the questionnaires showed that students living in concrete or steel-frame buildings had greater serum levels of antibody to Japanese cedar pollen than those living in wood buildings, indicating a possible relationship between the pollen sensitization and indoor environments.

Adolescent↗
PubMed1996

[Effects of propofol on contractility and electrophysiological properties of canine single cardiomyocytes].

We assessed the effects of propofol on contraction, action potentials and Ca2+ currents (Ica) in single ventricular cells in dog. Low concentrations of propofol 10(-5)M had no effects on contractile responses, but high doses above 10(-4)M of propofol decreased contractions. Propofol 10(-3)M reduced the duration of action potentials (time to 90% repolarization). Ica was decreased by propofol 10(-4)M without accompanying use-dependent manner. The present study indicates that clinical concentrations of propofol do not exert direct negative inotropic effects, but at supratherapeutic concentrations it inhibits cardiac contractility.

Action Potentials↗
PubMed1996

[Diagnosis of intracardiac thrombi by various imaging techniques and activation of platelets and coagulation-fibrinolysis in patients with cardioembolic stroke].

Recent epidemiological studies have suggested that 15 to 30% of all ischemic stroke is comprised of cardioembolic stroke. The presence of intracardiac thrombi might prove to be the most reliable tool when making a diagnosis of cardioembolic stroke, although not always easy to determine even with recent advanced technique. In this study, sensitivities to detect intracardiac thrombi of transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), cardiac-enhanced CT (CCT) and scintigraphy with indium-111-tropolone-labelled platelets (PSG) were compared, in order to provide a relevant guideline for the diagnosis of intracardiac thrombi in 83 patients suspected of cardioembolic stroke. Also studied was the correlation of intracardiac thrombi with activation of platelets and coagulation-fibrinolysis through performing various hemostatic tests in order to investigate their utility for the evaluation of in situ thrombosis or prothrombotic state in the heart chamber. Detection rates of intracardiac thrombi were 35% in TEE, 26% in CCT, 19% in PSG, and 11% in TTE. There was a significant difference in the sensitivity between TEE and TTE (p < 0.05). Left atrial thrombi were frequently detected in TEE (4 out of 5 patients) and CCT (7 out of 10), while they were found less in PSG (2 out of 4) an TTE (4 out of 10). Thrombi in the left appendage were visualized in 3 out of 3 by TEE, while only in 1 out of 3 by PSG, 1 out of 4 by TTE and 1 out of 4 by CCT. Left ventricular thrombi; CCT (3 out of 3), TTE (2 out of 3), PSG (1 out of 1); TEE was not performed since this technique could not be expected to provide high-quality images of left ventricular thrombi. Thus, left atrial thrombi were considered to be more sensitively detected by TEE and CCT, left appendage thrombi by TEE, and left ventricular thrombi by TTE and CCT. There was no patient in whom an intracardiac thrombus was visualized by PSG alone. On the basis of the results above, we propose the following guideline for the detection of intracardiac thrombi in patients presented with cardioembolic stroke. First, TTE and CCT appear to be relevant for screening tests because of simple and non-invasive techniques. These two tools might be sensitive enough to find left ventricular thrombi. Second, TEE should be recommended when a thrombus is suspected in the left atrium or appendage. Finally, PSG may be used to determine the activity of the thrombus, according to its necessity. Among the patients having intracardiac thrombi, frequently observed was the increase of beta-thromboglobulin, platelet factor 4, platelet lysis, thrombin-antithrombin III complex, D-dimer in 67%, 75%, 71%, 80% and 80%, respectively, as well as the shortening of platelet survival in 100%, while anrithrombin III was reduced in only 38%. In addition, when hemostatic abnormalities were compared between positive and negative groups of intracardiac thrombi, the shortening of platelet survival (p < 0.0001), the increase of platelet lysis, and the increase of D-dimer (p < 0.04) were more frequent in the positive group than in the negative group. These results indicate that the findings of activation of platelets and coagulation-fibrinolysis, except for the reduction of antithrombin III, especially the findings of platelet consumption and lysis as well as fibrinolysis activation are useful as sensitive parameters of in situ thrombosis or prothrombotic state, which may lead to the formation of intracardiac thrombi.

Adolescent↗