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Biomedical subjects

T Miyazaki

Publications and source records attributed to T Miyazaki.

At least 271 records · Page 15Linked to original sources
PubMed1997

Chemoenzymatic synthesis of the branched oligosaccharides which correspond to the core structures of N-linked sugar chains.

Synthetic routes are described to a partial structure common to all high mannose-type sugar chains and complex-type sugar chains based on a chemoenzymatic strategy which incorporates, (a) enzymatic synthesis of oligosaccharide blocks using glycosidases, and (b) chemical synthesis of the branching oligosaccharides via regioselective coupling. All reaction products correspond to key intermediates necessary for the construction of N-linked oligosaccharides and we have synthesized the branched tetra-manno-oligosaccharide high mannose-type sugar chain and the branched hexa-oligosaccharide complex-type sugar chain using this simple and direct method.

Acetylglucosaminidase↗
PubMed1997

Integrins and reproductive physiology: expression and modulation in fertilization, embryogenesis, and implantation.

OBJECTIVE: To review the available information regarding the role of integrins in reproductive physiology and to discuss their potential clinical implications. DESIGN: Studies that specifically relate to the expression and modulation of integrins in fertilization, embryogenesis, and implantation were identified through the literature and Medline searches. RESULT(S): Integrins are a class of adhesion molecules that participate in cell-to-cell and cell-to-substratum interactions and are present on essentially all human cells. All mammalian eggs express integrins at their surface, and the integrin alpha 6 beta 1 serves as a sperm receptor that mediates sperm-egg binding. In addition, certain integrin moieties appear to be regulated within the cycling endometrium. Specifically, the expression of beta 1 integrins in the early proliferative phase is restricted to the glandular epithelium, whereas stromal cells also express beta 1 integrins in the midsecretory phase. The expression of beta 1 integrins increases at the time of implantation and remains elevated in the decidua during early pregnancy. A disruption of integrin expression is associated with certain types of infertility in women. The apical surface of the mural trophectoderm does indeed possess functional integrins, and trophoblast interactions with extracellular matrix proteins largely depend on the integrin family of adhesion receptors. CONCLUSION(S): Integrins play particularly important roles in both fertilization and embryogenesis, including the process of implantation.

Animals↗
PubMed1997

In vitro inhibition of caries around a resin composite restoration containing antibacterial filler.

Class V cavities were prepared and restored with resin composite containing antibacterial filler powder (Apacider-AW, Ap-AW) using experimental restorations. The restored teeth were incubated in vitro with the cariogenic bacteria Streptococcus mutans IFO 13955. Ground sections were then prepared and examined using macrophotography. Lesions of the outer and inner wall were noted, and the depths of which the lesions penetrated were measured. We found that, in restorations containing 1-5 wt% Ap-AW, caries penetrated the marginal area, while in restorations containing 10 wt% Ap-AW the margin remained free of caries out to a distance of about 1.1 and 1.8 mm on the occlusal and gingival sides, respectively.

Biocompatible Materials↗
PubMed1997

Increased expression of vascular endothelial growth factor in human hepatocellular carcinoma.

BACKGROUND/AIMS: Angiogenesis is critical for the development and progression of solid tumors. The purpose of this study was to evaluate the possible role of vascular endothelial growth factor (which is considered to be one of the most important factors involved in tumor-associated angiogenesis), in human hepatocellular carcinoma. METHODS: Vascular endothelial growth factor gene and protein expression were analyzed by means of Northern hybridization and immunohistochemical methods in 5 hepatocellular carcinoma cell lines. Secretion of vascular endothelial growth factor was evaluated by immunoblotting of conditioned medium of these hepatocellular carcinoma cells. Further, we compared the level of vascular endothelial growth factor expression in hepatocellular carcinoma tissues along with that in surrounding tumor-free tissues obtained from 20 patients. We also analyzed mRNA expression of Flt-1, one of the vascular endothelial growth factor specific high-affinity receptors, in hepatocellular carcinoma cell lines. RESULTS: Northern hybridization analysis and immunohistochemistry revealed that all cultured hepatocellular carcinoma cells exhibited a high level of vascular endothelial growth factor mRNA. In addition, vascular endothelial growth factor secretion by Hep G2, one of the hepatocellular carcinoma cell lines, was shown by Western blot. In vivo, we observed vascular endothelial growth factor expression in both hepatocellular carcinoma and non-hepatocellular carcinoma tissues. However, in 12 of 20 cases, vascular endothelial growth factor mRNA levels were significantly up-regulated in hepatocellular carcinoma tissues. In the majority of cases (10 out of 12 cases) with abundant tumor vascularity, vascular endothelial growth factor mRNA up-regulation in hepatocellular carcinoma tissues was observed. We failed to detect Flt-1 mRNA expression in hepatocellular carcinoma cells. CONCLUSIONS: This study suggests that the possibility that hepatocellular carcinoma cells overexpress the vascular endothelial growth factor gene and protein. These findings support the hypothesis that vascular endothelial growth factor is one of the important factors involved in the angiogenesis of hepatocellular carcinoma, and may even be involved in the development and/or progression of hepatocellular carcinoma itself.

Adolescent↗
PubMed1997

New serine protease inhibitors with leukotriene B4 (LTB4) receptor binding affinity.

A series of new trypsin-like serine protease inhibitors, 1, 2 and 7-23, containing amidinobenzene moiety was found to show potent LTB4-receptor affinity. Among them, compounds 1 and 2 were found to be LTB4 receptor antagonists based on an inhibition assay of human polymorphonuclear neutrophil (PMN) intracellular calcium mobilization induced by LTB4. Compounds 1 and 2, which satisfy the reported structural requirements for good oral activity, are expected to show a balanced dual mode of action, i.e., protease inhibitory activity and LTB4 receptor antagonist activity, in vivo.

Amidines↗
PubMed1997

Selection of a broad repertoire of CD4+ T cells in H-2Ma0/0 mice.

According to past reports, H-2Ma0/0 mice express a single major histocompatiblity complex class II molecule, A(b), heavily loaded with a single peptide derived from the invariant chain, CLIP. Despite the highly restricted diversity of the class II:peptide complexes expressed on thymic stromal cells in the mutant animals, a large and diverse population of CD4+ T cells is positively selected. However, two important issues remained unresolved and are addressed here: Just how preponderant is CLIP occupancy of the class II molecules from H-2M0/0 mice? How extensive and functionally competent is the CD4+ population selected in the mutant animals? Our results argue that a single class II:peptide complex can select a very broad, though not complete, repertoire of CD4+ T cells.

Animals↗
PubMed1997

Enzymatic syntheses of GlcNAc beta 1-2Man and Gal beta 1-4GlcNAc beta 1-2Man as components of complex type sugar chains.

GlcNAc beta 1-2Man and GlcNAc beta 1-6Man were synthesized using the reverse hydrolysis activity of beta-N-acetylglucosaminidase from both jack beans and Bacillus circulans. In turn, Gal beta 1-4GlcNAc beta 1-2Man and Gal beta 1-4GlcNAc beta 1-6Man were synthesized regioselectively using the transglycosylation activity of beta-galactosidase from Diplococcus pneumoniae and B. circulans, respectively. These di- and trisaccharides are important components of complex type sugar chains and will be used as intermediates in our synthetic studies.

Acetylglucosaminidase↗
PubMed1997

Amyloid beta 2-microglobulin is modified with imidazolone, a novel advanced glycation end product, in dialysis-related amyloidosis.

We have recently demonstrated by immunohistochemistry that amyloid beta 2-microglobulin (beta 2m) is modified with advanced glycation end products (AGEs) in dialysis-related amyloidosis (DRA). To further investigate the role of the Maillard reaction in the pathogenesis of DRA, we produced a monoclonal antibody to imidazolone, a novel AGE, and a reaction product of arginine and 3-deoxyglucosone (3-DG) which was accumulated in uremic serum. Then we determined the localization of imidazolone in the amyloid tissues by immunohistochemistry using the antibody. The connective tissues in carpal tunnel and ligamentum flavum were obtained from six patients with carpal tunnel syndrome and two patients with destructive spondyloarthropathy. Imidazolone was localized to all the beta 2m-positive amyloid deposits in these patients. Western blotting using the antibody demonstrated that beta 2m extracted from the synovium amyloid of hemodialysis patients was modified with imidazolone. Further, beta 2m isolated from the blood ultrafiltrate of hemodialyzed patients was also modified with imidazolone. In vitro incubation of beta 2m with 3-DG produced imidazolone-modified beta 2m. In conclusion, amyloid tissue beta2m is modified with imidazolone in patients with DRA. 3-DG accumulating in uremic serum may be involved in the modification of beta 2m with imidazolone.

Aged↗
PubMed1997

Clinicopathologic features of submucosal carcinoma of the stomach.

A retrospective study of 155 patients with submucosal gastric carcinoma compared the clinicopathologic features with mucosal and muscularis proprial gastric carcinoma. Fifty-seven percent of the patients presented with gastrointestinal symptoms, whereas 36.1% had been detected by mass screening. The incidence of curative resection, lymph node metastasis, and complications were 96.1, 20.6, and 14.8%, respectively. Two patients died of sepsis and pulmonary infarction 30 days post-operatively. Five patients died of recurrent gastric cancer 1-5 years postresection. The overall 5-year survival rate was 90.2%. Recurrence patterns, histologic type, lymph node metastasis, lymphatic and venous infiltration, and growth pattern were similar to those of muscularis proprial carcinoma rather than mucosal carcinoma. Therefore, curative gastrectomy with extended lymphadenectomy (D2) may be feasible for submucosal carcinoma of the stomach.

Adenocarcinoma↗
PubMed1997

A case of widely split double P waves with marked intra-atrial conduction delay.

We report a 78-year-old man as the first documented case of double P waves separated by 400 msec on 12-lead ECG. These P waves had different polarities on lead V1. The first P wave represented activation of the lateral wall of the right atrium, and the latter P wave represented activation of the medial right atrium and the left atrium. Widely spaced double potentials were recorded craniocaudally along the line, presumably corresponding to the crista terminalis during sinus rhythm. For this to occur, conduction disturbance has to be present both in the upper and lower right atrium. Conduction disturbance in the upper right atrium would interrupt excitation from the sinus node to the medial wall, and conduction disturbance in the lower right atrium would interrupt excitation spreading from the lower lateral right atrium to the isthmus area where fragmented potentials were recorded. These multiple discrete lesions appear to constitute a unique electrical atriopathy in this patient.

Aged↗
PubMed1997

A 77-kilodalton protein of Cryptococcus neoformans, a member of the heat shock protein 70 family, is a major antigen detected in the sera of mice with pulmonary cryptococcosis.

Heat shock proteins (HSPs) from several pathogenic microbes have been shown to be target molecules of humoral responses as well as cellular immune responses. However, little is known about target molecules in pulmonary cryptococcosis. Western blotting analysis revealed that experimentally induced pulmonary cryptococcosis in (BALB/c x DBA/2)F1 mice was associated with the appearance of serum antibodies to a 77-kDa protein derived from Cryptococcus neoformans as well as to 18-, 22-, 25-, 36-, and 94-kDa proteins. Since the 77-kDa band also reacted with rabbit polyclonal antibodies against 70-kDa HSP (HSP70) family members, the protein was predicted to be a member of the HSP70 family. We also purified HSP70 directly from a C. neoformans cell extract by Mono Q fast protein liquid chromatography and ATP-agarose affinity column chromatography and showed that it was positive in immunoblot analysis using either serum from C. neoformans-infected mice or rabbit anti-HSP70 antibodies. N-terminal amino acid sequencing of this purified protein confirmed that the 77-kDa protein was a member of the HSP70 protein family. A 66-kDa protein, which coincidentally purified with the HSP70 protein and was identified as a member of the HSP60 family by N-terminal amino acid sequencing, was not reactive with sera from C. neoformans-infected mice. Thus, a protein associated with the HSP70 family and derived from C. neoformans was a major target molecule of the humoral response in murine pulmonary cryptococcosis.

Amino Acid Sequence↗
PubMed1997

Role of oxygen-derived free radicals in free growth retardation induced by ischemia-reperfusion in rats.

We investigated the involvement of oxygen-derived free radicals in the pathogenesis of the intrauterine growth retardation (IUGR) induced in Sprague-Dawley rats by ischemia-reperfusion. On day 17 of gestation, rats received saline, superoxide dismutase (SOD, 50,000 U/kg), catalase (CAT, 50,000 U/kg), or SOD + CAT subcutaneously 1 h before induction of 30 min of ischemia of the right uterine horn. On day 21 the placental level of lipid peroxides was significantly increased (P < 0.001 vs. sham-operated group) and IUGR was induced (P < 0.001 vs. left horn) in the saline-treated group n = 6). Pretreatment with SOD + CAT (n = 6) significantly inhibited the increase in placental lipid peroxides and prevented IUGR. The effect of ischemia-reperfusion on uterine blood flow, with or without pretreatment with radical scavengers, was investigated in separate experiments by laser-Doppler flowmetry. The induction of hypoperfusion 3 h after ischemia (blood flow -40 +/- 5%, n = 6, P < 0.05) was blocked by pretreatment with SOD + CAT (n = 6). Results indicate that oxygen-derived free radicals may be important in the development of postischemic uteroplacental hypoperfusion and of ischemia-reperfusion-induced IUGR in the rat.

Animals↗
PubMed1997

Effects of a thromboxane synthetase inhibitor (OKY-046) in an ischemia-reperfusion model of intrauterine growth retardation in Sprague-Dawley rats.

We investigated the effects of thromboxane (TX) A2 in rats with ischemia-reperfusion-induced intrauterine growth retardation. A saline solution or OKY-046, a selective TXA2 synthetase inhibitor, was injected into the caudal vein of pregnant rats on gestation day 17 before the induction of 60-min uteroplacental ischemia. The fetuses and placentas were delivered and examined on gestation day 21. Blood from the uterine vein of the occluded horn shortly after uteroplacental ischemia was collected, and plasma concentrations of TXB2 and 6-keto-prostaglandin (PG) F1 alpha were determined in the other rats on gestation day 17. Treatment with OKY-046 prevented the ischemia-induced reduction in the fetal body and placental weights. The ratio of 6-keto-PGF1 alpha to TXB2 was significantly increased in the OKY-046-treated group. We conclude that the action of TXA2 might play a salient role in our model.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Effects of nitric oxide on ovulation and ovarian steroidogenesis and prostaglandin production in the rabbit.

Evidence supports the involvement of nitric oxide (NO) in ovarian physiology. The present study was undertaken to investigate the role of the NO/NO synthase (NOS) systems in ovulation, oocyte maturation, ovarian steroidogenesis, and PG production using in vitro perfused rabbit ovaries. The addition of the NOS inhibitors, aminoguanidine hemisulfate salt (AG) and N-omega-nitro-L-arginine methyl ester (L-NAME), to the perfusate inhibited the ovulation induced by hCG in a dose-dependent manner, whereas D-NAME had no significant effect. Neither AG nor L-NAME affected the hCG-induced meiotic maturation of the ovulated ova. The exogenous administration of the NO generator, sodium nitroprusside (NP), induced follicle rupture in the absence of gonadotropin, but did not induce oocyte maturation. Inhibition of endogenous NOS by AG and L-NAME resulted in a significant elevation in the production of estradiol (E2), but not of progesterone, stimulated by hCG. The concomitant administration of NP significantly reduced the AG-stimulated production of E2 by ovaries perfused in the presence of hCG, which suggests that NO down-regulates ovarian E2 synthesis. Ovarian production of PGE2 and PGF2alpha in response to hCG was significantly blocked by L-NAME, and exogenous administration of NP stimulated the production of PGs in the absence of gonadotropin. Significant correlations were observed between the ovulatory efficiencies and the production of PGs by rabbit ovaries perfused with or without L-NAME. In conclusion, the ovarian NO/NOS system is involved in follicle rupture during the ovulatory process. NO may induce follicle rupture in rabbit ovaries at least in part by the stimulation of PG production.

Animals↗
PubMed1997

2-Arylmethyl-1,4-benzoquinones. II. Novel inhibitors of platelet aggregation: synthesis and pharmacological evaluation.

Two new series of 2-arylmethyl-1,4-benzoquinones (2 and 3) were synthesized for evaluation of their pharmacological activities. These compounds showed significant inhibition of platelet aggregation and some of them possessed a protective against endothelial cell injury. Structure-activity relationship studies indicated that 2b, 2d and 3b are potent inhibitors of platelet aggregation induced by arachidonic acid (AA) with an IC50 in the range of 1-10 micrograms/ml. Among them, 3b showed a significant inhibitory activity against endothelial cell injury caused by hydrogen peroxide (H2O2) at 1 microM.

Animals↗
PubMed1997

[Lifestyles and fatigue of caregivers of the impaired elders living at home].

The effects of the amount of time spent providing care to the elderly on caregivers' lifestyles and fatigue levels were examined. The subjects were 49 females administering in-home care to the elderly in H city located in the western part of Shizuoka prefecture. The caregivers' lifestyles were surveyed in terms of seven items from Breslow's Health Practice Index (HPI), and the caregivers' fatigue levels were assessed based on the Cumulative Fatigue Symptoms Index (CFSI). The subjects were divided into 3 groups for analysis according to the duration of their caregiving: a 24-hour group (n = 13), a between 4 & 24-hour group (n = 12) and a less than 4-hour group (n = 24). The following results were obtained. 1. The overall mean HPI score was 5.0 +/- 1.2 out of a possible 7. The HPI scores did not significantly differ between the three groups. However, the HPI score of the 24-hour group was the lowest and indicated that the 24-hour group had the smallest number of caregivers practicing proper sleeping pattern and nutritional balance in comparison with the other two groups. 2. The CFSI scores of the 24-hour group were significantly higher than those of the less than 4-hour group for indications of physical disorders, chronic tiredness and depressive feelings (p < 0.05). 3. In the less than 4-hour group, the HPI score was negatively correlated with CFSI score for chronic tiredness (p < 0.05).

Aged↗
PubMed1997

Phorbol ester enhancement of IL-3-dependent proliferation of primitive hematopoietic progenitors of mice in culture.

Protein kinase C (PKC) is a Ca++- and phospholipid-dependent protein kinase activated by diacylglycerol that is either released from cell membranes in response to certain growth factors or mimicked by 12-O-tetradecanoyl phorbol-13-acetate (TPA). We studied the effects of TPA on interleukin-3 (IL-3)-dependent colony formation of mouse bone marrow cells from mice injected with 5-fluorouracil 2 days before examination in order to clarify the significance of PKC in the proliferation of primitive hematopoietic progenitors. Although TPA alone did not support colony formation, TPA in combination with IL-3 increased colony numbers from 1.5 to 2 times that formed with IL-3 and vehicle. TPA increased not only the granulocyte/macrophage colonies, but also the multilineage colonies. A sequential colony count showed that TPA, unlike IL-6, did not hasten the appearance of colonies. Because TPA enhanced IL-3-dependent colony formation derived from lineage-negative marrow cells obtained from mice that received 5-FU 2 days before, it is possible that it might act directly on primitive progenitors. Prolonged pretreatment of marrow cells with TPA prevented TPA-augmented colony growth. Calphostin C, a specific PKC inhibitor, and certain specific tyrosine kinase inhibitors, such as genistein and herbimycin A, abrogated the enhancing effects of TPA on IL-3-dependent colony formation. These data suggest that TPA had a direct effect on the primitive progenitors and enhanced IL-3-dependent colony formation via activation of PKC and certain tyrosine kinases.

Animals↗