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Biomedical subjects

K Maeda

Publications and source records attributed to K Maeda.

At least 847 records · Page 47Linked to original sources
PubMed1993

Decreased activity of complement-mediated immune complex clearance in hemodialysis patients.

Complement-mediated immune complex (IC) clearance was examined in the sera from regular hemodialysis patients, who accumulated excess factor D in the circulation. Both complement activities for the inhibition of insoluble IC formation and the solubilization of insoluble IC were lower in the sera from these patients than in the sera from normal individuals. A similar decrease in complement activities was observed in normal serum fortified with excess factor D. In addition, complement-processed IC was found to be bound less effectively to human erythrocytes via complement receptor type 1 in the sera from these patients and from normal serum fortified with excess factor D than in normal serum. Gel-filtration HPLC analysis revealed a decrease in covalent binding of C3 fragments to IC solubilized in the sera from hemodialysis patients or in normal serum fortified with excess factor D. This supports the notion that lower complement-mediated IC clearance is due to the paucity of complement fragments bound to IC. It is suggested that some detrimental alterations in the complement system, probably due to excess factor D, cause decreased IC clearance activity in hemodialysis patients with chronic renal failure.

Antigen-Antibody Complex↗
PubMed1993

Right and left ventricular cultured endocardial endothelium produces prostacyclin and PGE2.

The endothelium profoundly affects subjacent vascular smooth muscle function. An analogous relationship between endothelial endocardial cells (EEC) and the myocardium is suggested by Brutsaert et al.'s observation that EEC modulate the contractility of subjacent myocardium. Prostanoids are a major product by which vascular endothelium affects smooth muscle, but similar prostanoid production by EEC has not been described. To determine whether both right and left ventricular EEC produce prostacyclin (PGI2) and prostaglandin E2 (PGE2), ovine EEC were cultured. EEC prostanoid production was measured under basal conditions and after stimulation with arachidonic acid or calcium ionophore A23187. EEC from both ventricles demonstrated sustained prostacyclin and PGE2 production. Prostacyclin production was 10 times greater than PGE2. These results suggest that endocardial prostanoid production could act both locally, to modulate platelet and myocardial function, and distally, on downstream vascular tone.

Animals↗
PubMed1993

An intrathoracic vagus nerve schwannoma invading the trachea.

A patient with a schwannoma of the intrathoracic vagus nerve is presented. The tumor invaded the trachea and caused dyspnea. It was successfully excised by a segmental resection of the trachea with end-to-end anastomosis. This instance of an intrathoracic vagus tumor invading the trachea is, as far as we know, the first reported in the world.

Cranial Nerve Neoplasms↗
PubMed1993

Differentiation and mineralization in osteogenic precursor cells derived from fetal rat mandibular bone.

The process of mineralization in cells prepared either by neutral protease digestion (Pro I) or by collagenase digestion (fifth cycle, Col V) from fetal rat mandible was studied in vitro. Alkaline phosphatase (ALPase) activity of cells in Pro I was low on day 3, increased rapidly from day 8, and reached a maximum on day 16, whereas that in Col V was high on day 2, then declined and thereafter elevated to reach a maximum on day 13. Both cell populations synthesized type I collagen in cell matrix and medium. Type III collagen was observed in cell matrix of Pro I on day 14 and 21. There was alpha 2 band of type V collagen in cell matrix of Pro I on day 21. Calcium deposition could be detected from day 14 in Pro I and from day 19 in Col V. The von Kossa-positive nodules were found on day 17 in Pro I and day 21 in Col V, respectively. The extracellular matrix in Pro I electron-microscopically consisted of well-banded collagen fibrils with a large number of calcified spherules. An elevation of ALPase activity, collagen synthesis, and mineral deposition occurred sequentially with a time lapse in Col V, and almost simultaneously in Pro I. The number of mineralized nodules was correlated with the density of plated cells in Pro I, but not in Col V. Dexamethasone caused an increase in the number of mineralized nodules in Pro I, but not in Col V, suggesting that Pro I contained osteoprogenitor cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkaline Phosphatase↗
PubMed1993

Increased synthesis and specific localization of a major lysosomal membrane sialoglycoprotein (LGP107) at the ruffled border membrane of active osteoclasts.

The immunocytochemical localization was investigated of a major lysosomal membrane sialoglycoprotein with a molecular mass of 107 kDa, which was designated as LGP107. The study utilized rat osteoclasts with different bone resorbing activity and osteoclast precursors at various stages of differentiation and maturation together with monospecific antibodies to this protein. Despite its localization primarily in lysosomes and endosomes in the other cell types examined, LGP107 was exclusively confined to the apical plasma membrane at the ruffled border of the active osteoclast, where the osteoclast is in contact with the bone surface. The protein was also concentrated in a number of endocytic vacuoles in the vicinity of the ruffled border membrane. However the labeling was not found in the basolateral membranes of the active osteoclast. The ruffled border membrane detached from the bone surface showed a marked decrease in the extent of the immunolabeling. The post- and/or resting osteoclasts, which were located away from the bone surface, were totally devoid of the membraneous localization of LGP107. No definite immunolabeling was found in the immature preosteoclasts. These results indicate that the protein is largely synthesized in the active osteoclast and rapidly translocated to the ruffled border membrane by vectorial vesicle transport. LGP107 is suggested to contribute to the formation and maintenance of the specialized acidic environment for bone resorption.

Animals↗
PubMed1993

Identification and nucleotide sequence of a gene in feline herpesvirus type 1 homologous to the herpes simplex virus gene encoding the glycoprotein H.

A gene encoding the glycoprotein H (gH) homologue of feline herpesvirus type 1 was identified and sequenced. It was located immediately downstream of the thymidine kinase gene within an EcoRI 6.6 kbp fragment. In addition, a partial UL21 homologous gene was located downstream of the gH homologous gene. The primary translation product of the gH homologous gene is predicted to consist of 821 amino acids with a molecular weight of 92.5 kDa. It possesses several characteristics typical of transmembrane glycoproteins, including a N-terminal hydrophobic signal sequence, C-terminal transmembrane domain, and putative N-linked glycosylation sites. Analysis of this protein revealed amino acid sequence homologies of 33.1% with equine herpesvirus type 1 (EHV-1) gH, 32.6% with EHV-4 gH, 29.1% with varicella-zoster virus gIII, 28.5% with pseudorabies virus gH, and 25.1% with herpes simplex virus type 1 gH. By Northern blot analysis, one of the transcripts specific for the gH homologous gene might be a mRNA of approximately 3.0 kb.

Amino Acid Sequence↗
PubMed1993

Structural analysis of oxidation products of urofuran acid by hypochlorous acid.

The oxidation of urofuran acid derivatives (1-2) by hypochlorous acid (HOCl) was investigated with the goal to possibly simplify the detection of their metabolites in biological materials. The oxidation products of 3-carboxy-4-methyl-5-propyl-2-furanpropionic acid (1) were obtained as an isomeric mixture and confirmed to exist as cis (3a) and trans (3b) isomers, based on their 13C nuclear magnetic resonance (NMR) spectra. Similarly, the products of 5-H substituted acid 2 obtained by oxidation with HOCl were identified as 4a and 4b by 13C and 1H NMR which indicated the presence of cis and trans hemiacetal hydrogens at C-5 in a ratio of 2.11:1. The oxidation was found to proceed in a manner different from that of the F-acid, because of the presence of the electron withdrawing COOCH3 group at C-3 which favored the nucleophilic attack on the carbonyl group to afford cis- and trans-2,5-dihydroxy-2,5-dihydrofurans (3a-b, 4a-b).

Chromatography, Gel↗
PubMed1993

A case report of resected primary duodenal carcinoma associated with early gastric cancer and cumulative results at 21 institutions in Japan.

A case of primary duodenal carcinoma simultaneously associated with an early gastric cancer is reported. A 72-year-old woman complaining of appetite loss and nausea was admitted in June 1988. Endoscopic examination showed an ulcerative lesion in the angle of the stomach and a Borrmann type 2 tumor in the bulb of the duodenum. Both lesions were revealed to be adenocarcinomas by histological examination of obtained biopsy specimens. Synchronous carcinoma was diagnosed and pancreatoduodenectomy and lymph node dissection were performed. The primary tumor of the duodenum was histologically a moderately differentiated adenocarcinoma, and the gastric cancer was a tumor limited to the mucosa. Metastasis was recognized in a regional lymph node (No. 14A). There has been no recurrence during the 4-year postoperative follow-up period. This result suggests that pancreatoduodenectomy with systematic regional lymph node dissection can greatly contribute to prolonging the survival of patients with advanced duodenal cancer. This case is very rare, in that curative operation was performed for a primary duodenal carcinoma simultaneously associated with an early gastric cancer.

Adenocarcinoma↗
PubMed1993

Bone-like nodules formed in vitro by rat periodontal ligament cells.

The periodontal ligament has been shown to possess the ability to regenerate both new cementum and alveolar bone as well as a self-regenerative capacity; however, the source of cementoblasts and osteoblasts is not still clear. We investigated the development of bone-like tissue in vitro by periodontal ligament cells, in order to determine whether the periodontal ligament contains osteoprogenitor cells. Periodontal ligament cells were obtained from periodontal ligament tissue attached to the maxillary incisors of 6-week-old WKA rats by means of the explant technique. Cells at passage #3 were cultured for long term in alpha-minimum essential medium containing 10% fetal bovine serum, antibiotics, and 50 micrograms/ml ascorbic acid, and were then examined using phase-contrast microscopy, histochemistry, transmission electron microscopy, X-ray microanalysis, and electron diffraction. Nodules were formed in the cultures, and when 10 mM Na-beta-glycerophosphate was added, these nodules became mineralized. The mineralized nodules were identified as bone-like elements in view of the presence of osteoblast-like and osteocyte-like cells, collagenous matrix, a mineral composed of hydroxyapatite, and intense alkaline phosphatase activity. The results show that the periodontal ligament contains osteoprogenitor cells, which differentiate into osteoblasts and produce bone-like tissue.

Animals↗
PubMed1993

DNA ploidy pattern of each carcinomatous component in adenosquamous lung carcinoma.

The relationship between adenocarcinomatous and squamous carcinomatous components in 12 surgically resected adenosquamous lung carcinomas was analyzed using DNA flow cytometry. Well-preserved parts of the tumor showing either adenocarcinoma or squamous cell carcinoma were identified on paraffin blocks. The cells obtained from each component were stained with propidium iodide for DNA flow cytometry. In the analysis of DNA flow cytometry, both components in the same tumor were defined as being related to each other when they showed diploidy or when at least one DNA index of abnormal clones between two aneuploid components was identical. According to these criteria, 8 (67%) of the 12 tumors showed a relationship between adenocarcinomatous and squamous carcinomatous components. This suggests that, despite the different phenotypes, both components of some adenosquamous lung carcinomas may share similar biological characteristics.

Adenocarcinoma↗
PubMed1993

Biocompatibility of tetracalcium phosphate cement when used as a bone substitute.

We evaluated the biocompatibility of tetracalcium phosphate (4CP) cement, made of 4CP powder and 40 wt% copolymer of polyacrylic acid/itaconic acid and 10 wt% citric acid solution. Light and electron microscopic characteristics were studied 3, 10 and 30 d after implantation. Neither inflammation nor foreign-body giant cell reaction was observed in the tissue adjacent to the implanted material. After 30 d, this material was surrounded with newly formed bone. Ultrastructural examination showed that osteogenesis occurred directly on the surface of the material. These findings suggest that this 4CP cement is biocompatible and possesses osteoconductive properties.

Animals↗
PubMed1993

Histamine stimulates normal human melanocytes in vitro: one of the possible inducers of hyperpigmentation in urticaria pigmentosa.

Isolated normal human melanocytes became enlarged and more dendritic in association with an increase in the activity of tyrosinase and the amount of b-locus protein when they were cultured with 0.1-10 microM histamine in vitro. However, histamine did not exert a proliferative effect on them. The stimulatory effect of histamine was observable even 6 h after starting the treatment. This stimulation seems not to be pharmacologically mediated through histamine receptors, because it was inhibited neither by pyrilamine, a histamine H-1 antagonist, nor by cimetidine, a H-2 antagonist. Imidazole derivatives that are rapidly metabolized from histamine in vivo and in vitro also stimulated the melanocytes. We propose that high concentrations of histamine and its imidazole metabolites continuously produced in the lesions of urticaria pigmentosa are probable causative factors of its characteristic skin pigmentation.

Adult↗
PubMed1993

An enzyme histochemical study of the behavior of rat bone cells during experimental apical periodontitis.

Bone alkaline and tartrate-resistant acid phosphatase activities were studied in paraffin sections obtained from experimentally induced periapical lesions of rats. These enzyme activities were demonstrated despite the use of high temperatures during embedding. In the formation phase, numerous osteoblasts and periodontal ligament cells showed strong alkaline phosphatase activity. On the other hand, a number of osteoclasts and preosteoclasts showed tartrate-resistant acid phosphatase activity in the activated resorption sites of periapical lesions. It is suggested that enzyme histochemical applications to paraffin sections are a useful means for clarifying the behavior of bone cells and that bone remodeling has occurred in the periapical lesions.

Acid Phosphatase↗
PubMed1993

Alterations of host response by a long-term treatment of roxithromycin.

Roxithromycin (10 mg/kg) was administered once-daily for seven or 28 days to mice intragastrically and its effects on cytokine synthesis were studied. Administration of roxithromycin for 28 days resulted in increased synthesis of interleukin (IL)-1 and tumour necrosis factor (TNF-alpha) production by macrophages, and the production of IL-2, IL-4 and interferon gamma by splenocytes. In contrast, 7 day administration of roxithromycin did not affect these parameters. Furthermore, clindamycin treatment did not significantly increase the capacity of host cells to produce cytokines, irrespective of the duration of treatment, when compared with the solvent control receiving 0.9% ethanol solution or the untreated controls. In addition, the supernatant of a 7 day culture of splenocytes with roxithromycin showed suppression of the production of TNF-alpha and prostaglandin E2 by mitogen-stimulated macrophages, and this suppressive activity was impaired by a monoclonal antibody to murine IL-4. Thus, this data suggests that roxithromycin may not only enhance the host defence system through increased cytokine synthesis by host cells, but also exhibit anti-inflammatory activity by including an anti-inflammatory cytokine, IL-4.

Adjuvants, Immunologic↗