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Biomedical subjects

M Iwamoto

Publications and source records attributed to M Iwamoto.

At least 289 records · Page 16Linked to original sources
PubMed1990

Stimulation of proteoglycan and DNA syntheses in chondrocytes by centrifugation.

So that the effects of biomechanical forces on the proliferation of chondrocytes and their proteoglycan synthesis could be studied, growth-plate and articular chondrocytes were maintained separately as packed masses in centrifuge tubes in the presence of 10% serum. In these conditions, the cells became re-organized into cartilaginous tissue in seven days. After ten days, they were centrifuged at gravities (g) of 1.3-27 for 24 h in a CO2 incubator. Control cells were maintained in the CO2 incubator without centrifugation. Centrifugation of growth-plate chondrocytes at 3 g resulted in a two-fold increase in incorporation of [35S]sulfate into proteoglycans, but had little effect on their [3H]thymidine incorporation into DNA. On the other hand, centrifugation of articular chondrocytes at 3 g for 24 h caused 1.5-fold increases in both [35S]sulfate incorporation into proteoglycans and [3H]thymidine incorporation into DNA. These results suggest that biomechanical forces have different effects on the growth and differentiation of articular and growth-plate chondrocytes.

Animals↗
PubMed1990

Effects of parathyroid hormone and calcitonin on alkaline phosphatase activity and matrix calcification in rabbit growth-plate chondrocyte cultures.

The effects of PTH and calcitonin (CT) on the expression of mineralization-related phenotypes by chondrocytes were examined. In cultures of pelleted growth-plate chondrocytes. PTH caused 60-90% decreases in alkaline phosphatase activity, the incorporation of 45Ca into insoluble material, and the calcium content during the post-mitotic stage. These effects of PTH were dose-dependent and reversible. In contrast, CT increased alkaline phosphatase activity, 45Ca incorporation into insoluble material, and the calcium content by 1.4- to 1.8-fold. These observations suggest that PTH directly inhibits the expression of the mineralization-related phenotypes by growth-plate chondrocytes, and that CT has the opposite effects.

Alkaline Phosphatase↗
PubMed1990

Biochemical evaluation of fetus with hypoxia caused by severe preeclampsia using cordocentesis.

Biochemical evaluation of the fetus using cordocentesis was performed in sixteen pregnant women with severe preeclampsia. In addition, FHR monitoring and Doppler flow velocimetry of the umbilical artery were examined in these cases before the cordocentesis. Other than blood gas and routine hematologic and biochemical examinations, catecholamine and hypoxanthine concentrations were also evaluated in some cases. According to the results it is obvious that the fetus of mother with severe preeclampsia is exposed to hypoxemia with the delta pO2, the difference from the mean in each gestation, of -22 mmHg. Especially, the prognosis of the severely growth-retarded babies with pO2 below 10 mmHg, or delta pO2 30 mmHg lower than the mean standard value, is poor. Among 16 babies, 4 with severe hypoxia or acidosis and growth retardation died perinatally. In contrast, severely growth-retarded babies without hypoxia or acidosis were alive. Since neither FHR monitoring nor Doppler velocimetry always reflect biochemical values of the fetus of a severe preeclamptic mother, hence the precise evaluation of fetal condition using cordocentesis is indispensable to determine the timing of the delivery and to prevent the neurological sequelae caused by hypoxia, especially when the fetal growth is retarded.

Adult↗
PubMed1990

Hematologic evaluation of growth retarded fetus by cordocentesis.

Fetal blood sampling by ultrasound-guided cordocentesis was performed in 22 IUGR fetuses in order to evaluate the fetal condition. All patients were referred to our hospital for further examination and management. In addition to hematological assessment we measured the velocity profiles of the umbilical artery with pulse-gated Doppler equipment. On the whole, pH and pO2 in the umbilical vein of IUGR fetuses were significantly lower and pCO2 higher, respectively, the corresponding values in controls. In particular, IUGR fetuses which had an etiology of maternal pre-eclampsia had fallen into hypoxemia. However, other laboratory values in IUGR did not differ from those of the controls except for the platelet count, which was low in the IUGR fetuses. Five fetuses with chromosomal abnormalities were found by analyzing the fetal blood. Since there are different etiologies inducing IUGR, fetus and umbilical artery velocimetry is not always predictive of the state of the IUGR fetus, hematological assessment is considered indispensable for further management.

Blood Chemical Analysis↗
PubMed1990

[A case of Aspergillus empyema with bronchopleural fistula].

Pleural aspergillosis is not a common disease and we recently experienced a case of Aspergillus empyema with bronchopleural fistula. A 76 year-old man was admitted to our hospital with productive cough and fever. Chest X-ray films showed infiltration in the right lower and left middle field and rather lucent area (clearing) in the right lower lung. Antibiotic therapy was administered but no improvement was obtained. Chest CT scan and right bronchography revealed empyema in the right back portion and bronchopleural fistula in the right lower lobe. Needle aspiration biopsy was performed and Aspergillus fumigatus was isolated from pus. A diagnosis of Aspergillus empyema with bronchopleural fistula was made. We began intrapleural administration of miconazole and empyema was improved partially. For the complete treatment, right lower lobectomy and decortication were performed, but unfortunately he died of acute pneumonia 16 days after operation.

Aged↗
PubMed1990

[Isolation of methicillin-resistant Staphylococcus aureus (MRSA) from sputum and clinical features of bronchopulmonary infection due to MRSA during 4 years (1985-1988)].

Clinical and bacteriological studies were carried out to investigate the isolation of MRSA from sputa and 13 cases with bronchopulmonary infections due to MRSA, during 4 years from 1985 to 1988 at the Hokusyo Central Hospital. The isolation rate of MRSA in Staphylococcus aureus from sputum increased from 0% in 1985 to 51.4% in 1988, and especially from patients in wards for aged people. Most of the MRSA strains were isolated from patients with underlying diseases, or bed sores. The roentgenographic appearances in bronchopulmonary infection patients due to MRSA, showed infiltration and cavitation. Seven out of 13 cases of bronchopulmonary infection due to MRSA died, in spite of therapy with current antibiotics, suggesting poor prognosis of this infection.

Adult↗
PubMed1990

[A case of pericostal abscess exacerbated during antituberculous chemotherapy].

A 27 Year-old female with pulmonary tuberculosis in right upper lobe developed right pericostal abscess during the course of antituberculous chemotherapy. The chest x-ray films on first admission showed infiltration with cavity formation and nodular shadows in the right upper lung field. Seven months after starting the antituberculous therapy with INH, RFP and EB, a new tumorous shadow appeared in the right chest wall. Microscopic examination of the specimen obtained by needle aspiration biopsy disclosed positive acid-fast bacilli. Because of the ineffectiveness of drug therapy on lesions in the right chest wall, surgical treatment was performed and the disease was diagnosed as pericostal abscess.

Abscess↗
PubMed1989

Regulation of colony formation of differentiated chondrocytes in soft agar by transforming growth factor-beta.

Fibroblast growth factor (FGF) induces colony formation by chondrocytes in soft agar (Y. Kato et al., J. Cell. Physiol., 1987), and the present study revealed that transforming growth factor-beta(TGF-beta) does not induce the same effect. TGF-beta did, however, increase the efficiency of colony formation by chondrocytes 3- to 4-fold in the presence of a maximal dose of FGF. Furthermore, TGF-beta decreased the concentrations of FGF needed for the induction of cell growth in soft agar by 40- to 100-fold. These results suggest that TGF-beta is involved in the control of cartilage growth possibly by increasing the responsiveness of chondrocytes to FGF.

Animals↗
PubMed1989

Stimulation of cartilage-matrix proteoglycan synthesis by morphologically transformed chondrocytes grown in the presence of fibroblast growth factor and transforming growth factor-beta.

The effects of transforming growth factor-beta (TGF-beta) on the synthesis of cartilage-matrix proteoglycan by cultured rabbit chondrocytes were examined. Rabbit chondrocytes were seeded at low density and exposed to a 1:1 mixture of Dulbecco's modified Eagle's medium and Ham's F-12 medium supplemented with 0.5% fetal bovine serum, 1% bovine serum albumin, 50 micrograms/ml ascorbic acid, and 2 x 10(-7) M hydrocortisone (Medium A). Various combinations of TGF-beta, insulin-like growth factor-I (IGF-I), and fibroblast growth factor (FGF) were also added to Medium A, and the chondrocytes were grown to confluency. Chondrocytes grown with TGF-beta or FGF alone became flat or fibroblastic, those grown with FGF and TGF-beta became very elongated and formed distinct foci, and those grown with FGF and IGF-I showed the spherical configuration characteristic of overtly differentiated chondrocytes. Nevertheless, the incorporation of 3H with glucosamine into the large, chondroitin sulfate proteoglycan synthesized by cultures with FGF and TGF-beta was similar to that in cells grown with FGF and IGF-I and five times that in cells cultured with FGF alone. The increases in incorporation of 3H reflected real increases in proteoglycan synthesis, because chemical analyses showed an increase in the accumulation of macromolecules containing uronic acid in cultures with FGF and TGF-beta or with FGF and IGF-I. However, FGF in combination with either TGF-beta or IGF-I had little effect on the incorporation of 3H into small proteoglycans or hyaluronic acid. These results indicate that chondrocytes morphologically transformed with TGF-beta and FGF fully express the differentiated proteoglycan phenotype rather than the transformed glycosaminoglycan phenotype.

Animals↗
PubMed1989

Effects of vanadate on tyrosine phosphorylation and the pattern of glycosaminoglycan synthesis in rabbit chondrocytes in culture.

The present study examined the effects of high doses of vanadate on glycosaminoglycan (GAG) synthesis and tyrosine phosphorylation in rabbit chondrocytes in confluent cultures. Although 6 microM vanadate increased the incorporation of [3H]glucosamine into chondroitin sulfate proteoglycans twofold, 40-60 microM vanadate suppressed this incorporation fourfold. Although 6 microM vanadate had little effect on [3H]glucosamine incorporation into hyaluronate, 40-60 microM vanadate increased this incorporation threefold. Chemical analyses confirmed that the increase in [3H]glucosamine incorporation into hyaluronate and the decrease in the incorporation into chondroitin sulfate proteoglycan correlated with increased hyaluronate content and decreased chondroitin sulfate content in the cell layers of vanadate-transformed cells. Chondrocytes exposed to 40-60 microM vanadate became typically transformed spindlelike cells. Furthermore, vanadate, at 6 and 60 microM, increased the overall level of phosphotyrosine by 8- and 31-fold, respectively, and 60 microM vanadate enhanced phosphorylation of many phosphotyrosine-containing proteins. These observations suggest that vanadate induces transformation-associated changes in the pattern of GAG synthesis when it induces excess phosphorylation on tyrosine in chondrocyte proteins.

Animals↗
PubMed1989

Hypertrophy and calcification of rabbit permanent chondrocytes in pelleted cultures: synthesis of alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor.

Cartilage calcification at specific sites is a key event that leads to skeletal development and growth. To obtain insights into the control of cartilage calcification, we examined whether cells distributed in permanent cartilage regions might have the ability to express the calcification-related phenotype in a permissive environment. Chondrocytes were isolated from the permanent and growth plate cartilages of 4-week-old rabbit ribs. They were seeded as a pelleted mass in a centrifuge tube and cultured in Eagle's minimum essential medium supplemented with 10% fetal bovine serum. These cells proliferated for several generations, and then synthesized large amounts of proteoglycans, yielding a cartilage-like tissue in 16 days. Cultures from the permanent and growth plate cartilages showed similar time courses for increases in DNA synthesis and proteoglycan production that reached similar maximal levels. Thereafter, they initiated the syntheses of alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor and induced matrix calcification without additional phosphate. The increases in alkaline phosphatase, 1,25-dihydroxycholecalciferol receptor, and calcium contents in cultures from the permanent cartilage were consistently delayed for 4-7 days relative to the growth plate-derived cells, but caught up by Day 28. The maximal levels of alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor in the cultures from the permanent cartilage were 40- to 100-fold higher than that of the in vivo permanent cartilage. These results provide evidence that permanent cartilage cells in postnatal young rabbit ribs have the capacity to express alkaline phosphatase and 1,25-dihydroxycholecalciferol receptor and induce calcification in a permissive environment, although they never express these calcification-related phenotypes in vivo.

Alkaline Phosphatase↗
PubMed1989

Further studies on a chemoattractant derived from Aleurites Fordii Hemsl. seed.

1. Activities stimulatory to PMN superoxide generation and chemotactic function were present in two separate gel chromatographic fractions of AFH-S and were designated AFH-S1 (500 kD) and AFH-S2 (38 kD). 2. Characterization studies of these activities revealed physiologic and pharmacologic characteristics dissimilar to those of other previously studied chemoattractants such as bacterial peptide FMLP.

Calcium↗