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Biomedical subjects

M Takagi

Publications and source records attributed to M Takagi.

At least 361 records · Page 20Linked to original sources
PubMed1997

Application of alginate gel as a vehicle for liposomes. II. Erosion of alginate gel beads and the release of loaded liposomes.

The possibility of producing calcium-induced alginate gel beads as a vehicle for liposomes was explored. The maximal loading of egg phosphatidylcholine liposomes (ca. 26 nm in diameter) in a fully-cured bead (1.2 mm in radius, initial alginate concn. of 4%) was 2.9 x 10(-6) mol/bead or ca. 18%, and the size of the bead slightly increased with an increase in liposome loading. The liposomes were well maintained within both fully-cured and washed beads. The liposome release from the fully-cured bead was much slower than that from the corresponding washed bead in a pH 7.4 releasing medium. The greater the liposome loading, the faster the release of the vesicles. The liposome release was investigated in terms of liposome loading, swelling of the gel body, calcium discharge and gel erosion, using washed beads. The liposome loading did not affect the bead erosion or calcium discharge but did the initial swelling ratio and liposome release. The results suggest that the loaded liposomes are not uniformly distributed in the bead but are rather gradually concentrated to the center. Such an inhomogeneous distribution of liposomes is possibly due to the fact that the gelation occurred instantly on the surface of the droplets, and the resulting gel network or layer acts as semipermeable membrane for liposomes and forces the vesicles to move into deeper concentric sections as gelation proceeds to the interior. As the liposomes loading increases, the forced migration might be very limited because of concentrically decreasing extra room to accommodate the vesicles in the bead.

Alginates↗
PubMed1997

Production of recombinant Der fI with the native IgE-binding activity using a baculovirus expression system.

Der fI is a cysteine protease contained in feces of mites and is one of major mite allergens. Recombinant Der fI (reDer fI) that is produced using a baculovirus expression system contains pro-sequences of different lengths. Most of these can be removed by acid treatment. However, IgE-binding activity of acid-treated reDer fI is lower than that of native Der fI at high protein concentrations, and N-terminal amino acids of acid-treated reDer fI are not uniform. Now, a method for processing of the pro-sequence has been developed by producing reDer fI E(-1)K with baculovirus expression system in which the carboxy terminal amino acid of the pro-sequence (glutamate) was replaced by lysine using site directed mutagenesis. No difference in the amount of production was observed upon introducing the mutation into the pro-sequence. Addition of lysylendopeptidase into the culture medium led to processing of the pro-sequence of reDer fI E(-1)K and proceeded the degradation of the other proteins in the medium. Lysylendopeptidase-treated reDer fI E(-1)K was easily purified with an anion exchange column, resulting in 20% increase of the yield. Lysylendopeptidase-treated reDer fI E(-1)K obtained through these processes was compared with the native Der fI. Although some differences were found in protease activity and reactivity with lectins, their N-terminal amino acid and the IgE-binding activity were the same as those of the native one, indicating its usefulness for diagnostic purpose.

Animals↗
PubMed1997

Advanced glycation endproducts stimulate interleukin-6 production by human bone-derived cells.

Advanced glycation endproducts (AGEs), which result from nonenzymatic reactions of glucose with tissue proteins, have been shown to accumulate on long-lived proteins in advanced aging and diabetes mellitus. Thus, AGEs have been implicated in some of the chronic complications associated with these disorders. In this study, we investigated the effects of the glucose-modified protein on the production of the potent bone resorption factors by cells derived from explants of human bone. AGEs stimulated the release of interleukin-6 (IL-6) in the culture supernatants from the bone-derived cells and increased the levels of IL-6 mRNA in the cells. By contrast, the levels of IL-11 in the culture supernatants were not altered by AGEs, and the other bone resorption factors IL-1 alpha and IL-1 beta were undetectable (< 1.0 pg/ml) either without or with the treatment of AGEs. Electrophoretic mobility-shift assays revealed that the transcription nuclear factor-kappa B, which is critical for the inducible expression of IL-6, was activated in the nuclear extracts from mouse osteoblastic MC3T3-E1 cells treated with AGEs. These results suggest that AGEs are involved in bone remodeling modulation by stimulating IL-6 production in human bone-derived cells.

Alkaline Phosphatase↗
PubMed1997

Hemodynamic effects of nicardipine and phentolamine in combination with norepinephrine in a canine low-output-state model.

Norepinephrine (NE) is one of the most potent positive inotropic drugs available for the treatment of low-output state following open-heart surgery. However, its inotropic effect is often masked by a significant increase of peripheral vascular resistance due to marked vasoconstriction. The purpose of the present study was to investigate whether the use of nicardipine (Nc) and phentolamine (Ph) in combination with NE could ameliorate the adverse vasoconstrictive action of NE. A low-output-state (LOS) model was produced by global myocardial ischemia due to electrically induced intermittent ventricular fibrillations in open-chest dogs. Twenty-eight dogs were divided into 6 groups according to the drugs infused after producing LOS. In the control group, hemodynamic changes similar to the clinical low-output state were observed, e.g., a decrease in cardiac output (CO) and left ventricular dp/dt, and an increase in the systemic vascular resistance (SVR). The use of NE alone produced marked increases in the systemic arterial pressure (SAP), heart rate, and SVR, with a slight increase in CO. The infusion of Nc alone produced decreases in SVR and SAP with a slight increase in CO. The concomitant infusion of NE and Nc produced increases in SV and CO, and decreases in SAP and SVR. The infusion of Ph alone produced no significant hemodynamic changes. The combined use of NE and Ph produced increases in CO, SAP and heart rate, but not to a significant extent. These results suggest that there are major advantages in the concomitant use of NE and Nc for the control of LOS.

Animals↗
PubMed1997

A patient with acromegaly who showed remarkable improvement of hyperglycemia after treatment with octreotide.

A case with diabetes mellitus associated with growth hormone (GH)-producing pituitary adenoma is described. A 56-year-old woman who had been treated for diabetes mellitus for 3 years, was admitted for the treatment of hyperglycemia. She showed a few acromegalic features and her plasma GH level was 146 +/- 16 ng/ml. After improvement of plasma glucose level by insulin injection, octreotide therapy (100 micrograms/8 hours) was started. Seven days after the initiation of octreotide therapy, the fasting plasma glucose level was almost normalized without insulin injection. After the octreotide treatment, urinary C-peptide excretion was significantly decreased and the plasma GH level became within normal range. In this case, octreotide appears to have improved the insulin sensitivity by reducing the plasma GH level.

Acromegaly↗
PubMed1997

Immunohistochemical and biochemical characterization of sulphated proteoglycans in embryonic chick bone.

The type and distribution of sulphated proteoglycans (PGs) in the midshaft subperiosteal bone of 15-18-day embryonic chick femurs were studied immunocytochemically and biochemically, using four monoclonal antibodies (MAb 2B6, 3B3, 1B5, and 5D4). These MAb specifically recognize epitopes in chondroitin 4-sulphate (C4-S) and dermatan sulphate (DS); chondroitin 6-sulphate (C6-S) and unsulphated chondroitin (C0-S); C0-S; and keratan sulphate (KS) respectively. Immunohistochemistry showed that staining of C4-S, DS, and KS, but not of C6-S and C0-S, was limited to osteoid, the cell surface of osteocytes, and to the walls of osteocytic lacunae and bone canaliculi in 15-18-day embryonic specimens. However, no significant difference in the distribution and intensity of immunostaining was observed in these specimens. Bone proteins were extracted from fresh 18-day embryonic specimens with a three extraction procedure, 4 M guanidine HCl (GdnCl, G-1 extract), 0.4 M EDTA (E-extract), followed by GdnCl (G-2 extract), to characterize mineral binding and collagenous matrix associated PGs in E- and G2-extracts respectively. Western blot analysis of E- and G2-extracts demonstrated that chondroitinase ABC-digested PGs with a molecular weight (Mr) approximately of 45,000 containing GAGs predominantly corresponding to C4-S and/or DS, with no detectable C6-S or C0-S present in the mineral and matrix phase, whereas KSPGs having an Mr of approximately 72,000 are only present in the mineral phase. These results indicate that embryonic chick bone contains small PGs having C4-S, DS, and KS chains with preferential localization to osteoid, the cell surface of osteocytes, and to the walls of osteocytic lacunae and bone canaliculi.

Animals↗
PubMed1997

Vitamin E ameliorates the renal injury of Dahl salt-sensitive rats.

Recently, hyperlipidemia as well as hypertension has been observed in Dahl salt-sensitive (S) rats. In this study, to investigate whether the lipid abnormality is involved in the renal injury of Dahl S rats, we examined the effect of vitamin E on glomerular sclerosis, as vitamin E is an inhibitor of lipid oxidation. Dahl S rats were given a high salt diet (8% NaCl) containing either normal vitamin E (2 mg/100 g) or high vitamin E (50 mg/100 g) for 4 weeks. Dahl salt-resistant (R) rats were given a high salt and normal vitamin E diet. The blood pressure in the Dahl rats increased and was not suppressed by the vitamin E supplement. Serum cholesterol and triglycerides in Dahl S rats were higher than in Dahl R rats at both 0 and 4 weeks. Vitamin E lowered the serum cholesterol level in Dahl S rats at 4 weeks (126 +/- 5 v 150 +/- 12 mg/dL, P < .01). Urinary protein excretion and serum creatinine increased in Dahl S rats, and vitamin E inhibited the increases significantly (urinary protein, 70.7 +/- 0.9 v 178.0 +/- 8.8 mg/day, P < .01; serum creatinine, 0.45 +/- 0.02 v 0.63 +/- 0.05 mg/dL, P < .01). Serum lipid peroxide (LPO) was higher in Dahl S rats than in Dahl R rats, and vitamin E lowered LPO in Dahl S rats (2.10 +/- 0.03 v 2.70 +/- 0.04 nmol/mL, P < .01). In the histologic study, sclerosing score (SS) of glomeruli, which represents the degree of glomerulosclerosis semiquantitatively, was higher in Dahl S rats than in Dahl R rats. Vitamin E lowered SS (114 +/- 3 v 157 +/- 6, P < .01) and ameliorated arterial injuries such as medial thickness with partial necrosis and severe fibrinoid proliferation with inflammatory cell infiltration. In all rats, SS was strongly correlated with urinary protein (r = 0.93, P < .01), serum cholesterol (r = 0.86, P < .01), and serum LPO (r = 0.89, P < .01). These results suggest that the renal injury in Dahl S rats is caused not only by hypertension but also by hyperlipidemia. Therefore, vitamin E might ameliorate the renal damage by inhibiting the oxidation of lipids.

Animals↗
PubMed1997

[Stanford type A aortic dissection with closed false lumen: analysis of prognostic factors at initial CT or MRI].

Nineteen patients with Stanford type A acute aortic dissection with closed false lumen were reviewed. In the follow-up examinations, ulcerlike projection (ULP) in the ascending aorta (AA) or aortic arch (AR) was identified in 8 of 19 patients. In 5 of these 8 patients, acute cardiac tamponade occurred and 3 of them died. In the other 11 patients, there was no mortality, and only one patient underwent elective surgery. The appearance of ULP in the AA/AR is considered an indication for urgent surgery because it is regarded as a precursor of lethal complications such as cardiac tamponade. The purpose of this study was to investigate predictors of the appearance of ULP in the AA/AR with early imagings (CT or MRI) before the appearance of ULP. The patients were divided into two groups: patients with ULP in the AA/AR (8 patients) and others (11 patients). Initial CT or MRI findings of the thoracic aorta were retrospectively statistically analyzed in each group. Three predictive factors were statistically significant for the appearance of ULP in the AA/AR (diameter of the AA > or = 5 cm, thickness of the false lumen of the AA > or = 1 cm, thickness of the false lumen of the AA > or = that of the descending aorta). Close attention should be paid, if any of these 3 factors is observed at initial CT or MRI.

Aged↗
PubMed1997

[Resection of multiple thymoma: a case report].

A 74-year-old male, who had been treated for hypertension at the out-patient clinic, was admitted to our hospital because of an abnormal shadow on a chest radiograph. After diagnosis of thymoma by needle biopsy surgery was carried out on July 6, 1995, when an extended thymectomy along with removal of the entire tumor was done. During the surgery it was noticed that there was not one, but two independent tumors located in the anterior mediastinum, the upper left portion was growing from the level of the crania to the left brachiocephalic vein, whereas the lower right portion was growing towards the right thoracic cavity in front of the pericardium. Both tumors were encapsulated firmly, and connected to each other by scantly loose connective tissues. There was no continuity or sarring between the two tumors. Histologically both were diagnosed to be lymphocytic thymoma. We believe that this case is a good example of multiple thymomas and provides evidence of the potential multicentricity of thymoma. It is possible that extended thymectomy may be seeded for a complete resection of thymomas.

Aged↗
PubMed1997

Genetic differentiation among three populations of Anopheles minimus of Guangxi and Yunnan Provinces in the People's Republic of China.

Electrophoretic studies were carried out on isozymes of 3 populations of Anopheles minimus collected from Guangxi and Yunnan Provinces of the People's Republic of China in 1993. Eight proteins were analyzed by 5% polyacrylamide gel electrophoresis. The most variable population, 'Yunnan-Field' (Y-F), was highly polymorphic at 14 of 20 loci (P = 0.700) with an average heterozygosity H of 0.340. P values of 0.500 and 0.700, and H values of 0.220 and 0.210 were obtained for each from 'Guangxi-Lab' (GX-L) and 'Yunnan-Lab' (Y-L), respectively, Nei's genetic distances (D) between Y-L and GX-L, Y-F and GX-L, and Y-F and Y-L were 0.1131, 0.1946 and 0.1069, respectively. These results suggest that GX-L is distant from the 2 other populations, Y-L and Y-F, and that this genetic differentiation between the 2 populations of Yunnan and Guangxi Provinces corresponds to the forms A and B, which were morphologically classified by Xu et al (unpublished).

Animals↗
PubMed1997

Hydrophobic effect of alkyl substituents on DNA intercalation of a dye.

Naphthalene imides carrying alkyl chains of different length were synthesized to evaluate the hydrophobic effect on DNA interaction with small molecules. These dyes bind to DNA with moderately high affinity of 10(4)-10(5) M-1 and raise the melting temperature of the DNA duplex by 8-18 degrees C at a 0.2 molar ratio of dye to DNA-p (phosphate unit). However, both the DNA binding affinity and DNA duplex stability decrease with an increase in the hydrophobicity (logP) of the dye. These results demonstrate that the interaction of the hydrophobic alkyl chain of the dye with the DNA groove destabilizes the DNA structure, presumably by removing the structure-stabilizing water from the DNA groove.

Alkylation↗
PubMed1997

DNA sequence dependent binding modes of bis(vinylpyridinium)benzene derivatives.

The DNA binding selectivity of new dicationic ligands based on the bis(vinylpyridinium)benzene unit has been investigated by means of UV-Vis absorption spectroscopy. From the experimental results it is concluded that these extended pi-electron bridged viologens have relatively high affinity to AT base pair sequences whereas the binding to GC pairs is about 10 times lower, and binding affinity depends on minor variation in the ligand structure. Linear type ligand exhibits two binding mode interaction, intercalation at high dye concentration which undergoes switching to groove binding at low ligand concentration.

Base Composition↗
PubMed1996

Structure of the cyclic glucan produced from amylopectin by Bacillus stearothermophilus branching enzyme.

The thermostable branching enzyme (BE, EC 2.4.1.18) from Bacillus stearothermophilus TRBE14 produces large cyclic glucans from waxy rice amylopectin similar to those obtained from amylose as described elsewhere [H. Takata, T. Takaha, S. Okada. M. Takagi, and T. Imanaka, J. Bacteriol., 178 (1996) 1600-1606]. The structure of the product (P-1) from the late-stage reaction was analyzed in detail. The weight-average degree of polymerization (dpw) of P-1 was 900. Its chain-length distribution was not significantly changed compared with that of amylopectin, although the amount of long chains (dp > 38) was slightly decreased. The cyclic component of P-1, which was isolated by the extensive action of glucoamylase, had dpw of 49. Three point five alpha-1,6 linkages were directly involved in the formation of the ring structure with several non-cyclic side chains linked to the ring. Based on these results, the action and new roles of BE are discussed.

1,4-alpha-Glucan Branching Enzyme↗
PubMed1996

Oviductal progesterone concentration and its spatial distribution in cyclic and early pregnant cows.

Changes and local distribution of oviductal progesterone (P(4)) concentration during the estrous cycle and early pregnancy in cows were investigated. Intact reproductive tracts were collected from 16 Holstein cows at an abattoir. Samples were classified in to 4 stages (follicular, postovulatory, luteal and early pregnant,< 20 d) based on visual observation of corpus luteum (CL), uterine characteristics and luteal P(4) concentrations. Oviducts were separated from the uterus at the utero-tubal junction and divided into 4 parts: fimbriae, proximal, medial and distal parts. Luteal tissue samples were also collected. Progesterone levels in oviductal and luteal tissues were determined by radioimmunoassay (RIA). Comparatively higher (P < 0.001) P(4) levels were found in stages with a functioning CL ( luteal phase and early pregnancy) than in those with a regressing CL (follicular phase and post ovulation). The oviduct ipsilateral to the CL bearing ovary during the luteal phase and early pregnancy showed higher ( P < 0.001) P(4) concentrations than the contralateral side. Such a difference was not observed during the follicular phase or post ovulation. The ipsilateral oviduct to the functioning CL at early pregnancy showed higher (P <0.05) P(4) levels than at the luteal phase, while no significant difference in luteal P(4) levels between these 2 stages was observed. Neither were any differences in P(4) concentration within the oviduct observed during any phase of the estrous cycle or during early pregnancy. A positive relationship between luteal and oviductal P(4) concentrations was noted. In conclusion, changes in P(4) levels in the oviduct depend on the location and functional stage of the CL. Localized levels of P(4) in the oviduct may be due to local delivery of P(4) from the CL.

Journal Article↗