Biomedical subjects

M Yamaguchi

Publications and source records attributed to M Yamaguchi.

At least 613 records · Page 34Linked to original sources

PubMed1997

Heterogeneity in androgen receptor levels and growth response to dihydrotestosterone in sublines derived from human hepatocellular carcinoma line (KYN-1).

Heterogeneity in the growth response to androgen and androgen receptor (AR) status in an AR-positive human hepatocellular carcinoma (HCC) line, KYN-1, was investigated in the present study. Seven sublines were obtained from KYN-1 by the limited dilution method. Four of them had no detectable amounts of AR and did not show any growth response to dihydrotestosterone (DHT) at the concentration up to 1000 nM, while the other three had varying amounts of both cytosolic and nucleosolic AR that were 5- to 7-fold higher than that of the parent cell. In the parent cell, the addition of DHT caused a modest but significant increase in the cell number (21%) in a 14-day culture. Such effect was increased by 2- to 7-fold in two AR-positive sublines. In addition, the sensitivity of the response in these two sublines was increased by up to 24-fold. The one remaining AR-positive subline did not show any growth response to DHT, although the behavior of its AR in sucrose gradient ultracentrifugation and Western blotting was the same as that of the other two sublines. These data clearly show that sublines derived from an established human HCC line have a broad heterogeneity in the growth response of HCC to androgen as well as in AR status and could be classified into three groups on the basis of the growth responsiveness to androgen and the AR expression.

Blotting, Western↗

PubMed1997

Effect of tension-force on plasminogen activator activity from human periodontal ligament cells.

The plasminogen activator (PA)-plasmin proteolytic system has recently received considerable attention because of its participation in a wide variety of biological activities and in pathological conditions involving tissue destruction. Excessive mechanical stress such as occlusal trauma is associated with alveolar bone loss in severe periodontitis. Therefore, mechanical stress may involve degradation of the extracellular matrix by occlusal trauma through activation of the PA-plasmin proteolytic system. We examined the effects of mechanical stress on PA activity, gene expressions of tissue type (t) PA, urokinase type (u) PA and PA inhibitor-1 (PAI-1) in human PDL cells. Human PDL cells were cultured on flexible-bottomed culture plates and placed on a Flexercell Strain Unit. The cells were flexed at 6 cycles (5 s strain, 5 s relaxation) at 9% and 18% elongation for 5 d. Application of tension-force induced significantly higher PA activity in stressed PDL cells than in non-stressed controls, and did so in a time- and magnitude-dependent manner (p < 0.001, ANOVA). Western-blot analysis revealed that the high level of activity was due to tPA and not uPA. Gene expression of tPA mRNA in stressed PDL cells, as examined by RT-PCR, increased on d 5. These findings suggest that tPA may be involved in periodontal metabolism in response to mechanical stress.

Analysis of Variance↗

PubMed1997

BAY K 8644 and ClO4- potentiate caffeine contracture without Ca2+ release channel activation.

Effects of perchlorate (ClO4-) and BAY K 8644 on caffeine contracture and Ca2+ release channel current were studied in frog skeletal muscle. Single fibers produced a small transient contracture on addition of 2.2 mM caffeine. ClO4 at 10 mM enhanced caffeine contracture 3.7-fold. This effect was inhibited by 10 microM nifedipine pretreatment. An increase in caffeine contracture was also obtained after exposure to 0.1 microM BAY K 8644 for 1 h. At 20 mM, external K+ potentiated caffeine contracture 2.2-fold. ClO4- (< 10 mM) and BAY K 8644 (0.1-1 microM) did not affect open probability (Po), unitary conductance, and open and closed time constants of the Ca2+ release channel current. BAY K 8644 at 0.1 microM did not further enhance the channel that had been activated by 2 mM caffeine. However, 20-30 mM ClO4 increased Po significantly and led the channel to a long open state by increasing the slow open time constant and decreasing the fast closed time constant. These results suggest that binding of ClO4 and BAY K 8644 to dihydropyridine receptors elicits a further increase in Ca2+ release from the sarcoplasmic reticulum.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

PubMed1997

Ethanol enhances caffeine-induced Ca2+-release channel activation in skeletal muscle sarcoplasmic reticulum.

When sarcoplasmic reticulum (SR) vesicles prepared from frog skeletal muscles were actively loaded with Ca2+, pretreatment of the SR with 2.2 mM (0.01%) ethanol for 30 s significantly potentiated 5 mM caffeine-induced release of Ca2+ from 16.7 +/- 3.7 nmol/mg protein in control without ethanol to 28.0 +/- 2.6 nmol/mg (P < 0.05, n = 5). Ethanol alone caused no release of Ca2+ from the SR. Exposure of the Ca2+-release channel, incorporated into planar lipid bilayers, to 2 mM caffeine significantly increased open probability (Po) and mean open time, but unitary conductance was not affected. Ethanol (2.2 mM) enhanced caffeine-induced Ca2+-release channel activity, with Po reaching 3.02-fold and mean open time 2.85-fold the values in the absence of ethanol. However, ethanol alone did not affect electrical parameters of single-channel current, over a concentration range of 2.2 mM (0.01%) to 217 mM (1%). The synergistic action of ethanol and caffeine on the channel activity could be attributable to enhancement of caffeine-induced release of Ca2+ from the SR vesicles in the presence of ethanol.

Animals↗

PubMed1997

A monoclonal antibody against ICAM-1 suppresses hepatic ischemia-reperfusion injury in rats.

Since intercellular adhesion molecule-1 (ICAM-1) has been reported to play a major role in reperfusion injury after ischemia, we estimated the effects of an anti-rat ICAM-1 monoclonal antibody (1A29) on hepatic ischemia-reperfusion injury in rats. Partial liver ischemia was achieved by clamping hepatic hilar vessels supplying the cephalad three lobes of the liver for 90 min. An intraportal injection of 1A29 was given 5 min after revascularization (n = 28), and saline was injected in control rats (n = 28). Changes in the proportion of liver necrosis, hepatic tissue blood flow, serum liver enzymes and liver neutrophil sequestration were analyzed at 6, 24, 48 and 72 h after revascularization. The intraportal injection of 1A29 significantly reduced the hepatocellular necrosis, restored the hepatic tissue blood flow at 24, 48 and 72 h of reperfusion (p < 0.05 or p < 0.01), and significantly suppressed the levels of serum liver enzymes at all time points during reperfusion (p < 0.01, respectively). The 1A29 treatment significantly reduced the number of neutrophils at the pericentral area, while those at the periportal area were similar in the two groups. The results suggested that ICAM-1 plays an important role in the development of hepatic ischemia-reperfusion injury, and that 1A29 reduced the injury possibly caused by cytotoxic inflammatory responses, based on neutrophil adherence to pericentral sinusoids.

Alanine Transaminase↗

PubMed1997

Allopurinol reduced hepatic ischemia-reperfusion injury exacerbated by inhalation of high-concentration oxygen in rats.

Exposure to high-concentration oxygen (O2) increases lipid peroxidation of the cellular membrane, leading to tissue injury which may involve hepatic ischemia-reperfusion (I/R) injury. We examined the effects of inhaling high-concentration O2 on hepatic I/R injury with allopurinol, which is a xanthine oxidase inhibitor. Partial hepatic ischemia was performed in rats with or without allopurinol under 21 or 100% O2 inhalation. Levels of lipid peroxide, serum liver enzymes, and hepatocellular oxidative stress in the 100% O2 group were significantly higher than in the 21% O2. Administration of allopurinol significantly inhibited those changes in the 100% O2 group. Severe degeneration of mitochondria were noted in the 100% O2 group, but appeared to be reduced by allopurinol. Results suggest that inhalation of high-concentration O2 during liver surgery may increase lipid peroxidation and exacerbate hepatic I/R injury, but those changes may be prevented by allopurinol.

Alanine Transaminase↗

PubMed1997

A 15.5-year follow-up study of stroke in a Japanese provincial city. The Shibata Study.

BACKGROUND AND PURPOSE: Change toward Western lifestyles, particularly during the high economic growth period (approximately 1960 to 1975), dynamically altered stroke frequency and the distribution of risk factors in the Japanese. We reexamined their association after this environmental change by a cohort study. METHODS: The cohort (2302 subjects) comprised residents aged 40 years or older of the Akadani-Ijimino district in Shibata City, Niigata Prefecture, Japan, who were followed up from 1977 for 15.5 years. RESULTS: Crude incidence rates per 1000 person-years for all strokes were 5.22 for men and 4.36 for women (3.02 and 2.18 for cerebral infarction, 0.65 and 1.06 for intracerebral hemorrhage, and 0.41 and 0.34 for subarachnoid hemorrhage, respectively). Multivariate analyses performed with the Cox proportional hazard model revealed these risk factors to be independently significant: for cerebral infarction in men, age, blood pressure, atrial fibrillation, albuminuria, funduscopic abnormality, and current smoking: for cerebral infarction in women, age, atrial fibrillation, and history of ischemic heart disease; for intracerebral hemorrhage in men, age and funduscopic abnormality; for intracerebral hemorrhage in women, age, blood pressure, and light physical activity; for all strokes in men, age, blood pressure, atrial fibrillation, albuminuria, funduscopic abnormality, current smoking, and heavy physical activity; and for all strokes in women, age, atrial fibrillation, and light physical activity. CONCLUSIONS: Most traditional risk factors, including blood pressure and its related organ diseases, were confirmed, but serum total cholesterol had almost no effect. Physical activity had both negative and positive effects on stroke risk. In these findings, however, some differences related to sex were also observed.

Adult↗

PubMed1997

In vitro cellular aging stimulates interleukin-1 beta production in stretched human periodontal-ligament-derived cells.

Although the severity of periodontal disease is known to be affected by host age, the pathological role of aging in periodontal disease, and especially that attributable to trauma from occlusion, has not been well-characterized. Interleukin (IL)-1 beta is a key mediator involved in periodontal diseases, a potent stimulator of bone resorption. Furthermore, it is produced by human periodontal ligament (PDL) cells in response to mechanical stress. To investigate the age-related changes in the biosynthetic capacity of IL-1 beta in PDL cells, we examined the effects of in vitro cellular aging with mechanical stress on IL-1 beta protein and gene expression by human PDL cells. Human PDL cells (young = 5th or 6th passage; old = 18-20th passage) were cultured on flexible-bottomed culture plates, and the cells were deformed at 6 cycles per min at 2 steps of tension force for 1 to 5 days. We found a two-fold increase in IL-1 beta production by old PDL cells subjected to mechanical tension compared with that by young PDL cells, although the constitutive levels of IL-1 beta were similar in both the young and old PDL cells. This increase was tension-dependent. IL- 1 beta mRNA was also detected in both cell types under basal conditions, and its expression was further enhanced by application of mechanical tension by use of reverse-transcription-polymerase chain-reaction (RT-PCR) and in situ hybridization methods. The increase in signal rate was higher in the old cells than in the young cells. IL-1 beta-converting enzyme mRNA remained unchanged. It is possible that a large amount of IL- 1 beta produced by PDL cells from an aged host in response to mechanical force may be positively related to the acceleration of alveolar bone resorption.

Adolescent↗

PubMed1997

3 beta,5 alpha-Dihydroxycholestan-6-one exists in human blood.

3 beta,5 alpha-Dihydroxycholestan-6-one was detected in fresh human plasma at the concentration of 14-44 ng/mL. The oxysterol binds specifically to phorbol ester specific binding protein in vitro, and may be an endogenous ligand of the protein.

Animals↗

PubMed1997

Spermine modulates calcium flux through the rat erythrocyte membrane.

The uptake of 45Ca by inside-out erythrocyte membrane vesicles (IOV) was dose-dependently inhibited by spermine. A cationic substance, Mg2+, did not affect this inhibitory activity of spermine. Ca(2+)-ATPase activity, however, was not inhibited by spermine at a concentration that could inhibit the uptake of 45Ca by the IOV. The release of 45Ca from IOV was significantly accelerated by spermine. Spermine bound to the surface of the IOV and was removed by treatment with acetic acid. These results suggest that spermine stimulates the release of Ca2+ from the IOV (or uptake of Ca2+ by erythrocytes) via an effect on the outer surface of the IOV (or the inner surface of erythrocytes).

Animals↗

PubMed1997

Photoaffinity labeling of tumor promoter-binding protein (CN-TPBP) and preparation of affinity sorbent gels.

Cytosolic-nuclear tumor promoter-specific binding protein (CN-TPBP) was photoaffinity-labeled with a specific ligand, 3beta,5alpha-dihydroxycholestan-6-one (YS-64). Analysis by ODS-HPLC of peptide fragments obtained from the labeled CN-TPBP by trypsinization indicated the existence of a single specifically labeled site. Affinity gels for the purification of CN-TPBP were then prepared. As ligands for the affinity gels, 12-O-tetradecanoylphorbol 13-acetate (TPA), a typical phorbol-type tumor promoter, and benzolactam-V8-310 (BL-V8-310), a structural/biological mimic of teleocidin-class tumor promoters, were adopted. The use of these gels afforded a protein that showed a single band of 58 kDa on SDS-PAGE.

Affinity Labels↗

PubMed1997

Apoptosis to HL-60 by humulone.

Humulone, a bone resorption inhibitor isolated from hop extract, induced apoptosis in the premyocytic leukemia cell line HL-60 between 1 and 100 micrograms/ml. Our data suggested that there was a correlation between the apoptosis-inducing activity of humulone and its antioxidative activity.

Anti-Infective Agents↗

PubMed1997

Effects of medium-chain fatty acids and their acylglycerols on the transport of penicillin V across Caco-2 cell monolayers.

The transport-enhancing effects of medium-chain fatty acids (caproic, caprylic, and capric acids) and their acylglycerols (mono-, di-, and triacylglycerols) were investigated by using Caco-2 cell monolayers as a model of the human intestinal epithelium. Penicillin V was used as a model for a hydrophilic bioactive compound. Among the fatty acids and acylglycerols tested, 1,2-dicaproin, monocaprin, monocaprylin, and capric acid sodium salt effectively enhanced the transport rate, whereas other substances enhanced the rate only slightly or not at all. With each of these four substances, the rate of enhancement was proportional to the concentration at low concentrations, but leveled off at high concentrations. The transport-enhancing effects were well correlated with the reduction in surface tension and with a physico-chemical parameter, denoted by the surface energy-lowering coefficient, characterizing the surface activity of a substance.

Caco-2 Cells↗

PubMed1997

The effects of corn peptide ingestion on facilitating alcohol metabolism in healthy men.

We prepared corn peptide (CP), a vegetable oligopeptide and tried to discover the effects of its ingestion on facilitating alcohol metabolism in healthy adult men. Ten healthy male volunteers ingested 5 g of CP, wheat peptide (WP), pea peptide (PP), alanine, or leucine 30 min before alcohol intake at a dose of 0.5 g/kg, and blood ethanol and plasma amino acid concentrations were measured during a 2-h observation period after alcohol intake. In subjects who ingested CP, the blood ethanol level was lower than that in the WP, alanine and leucine ingestion groups, but did not decrease as compared to the control when they ingested PP. Similarly there was a difference in the blood ethanol level between alanine and leucine ingestion groups, and leucine ingestion was more effective than alanine against the reduction of the increase in blood ethanol level. On the other hand, there was no significant difference in the plasma concentrations of individual amino acids except alanine, leucine, or lysine after alcohol intake among experimental groups as compared to the control. CP ingestion significantly elevated plasma alanine and leucine rather than other groups during a 2-h observation period. These results suggested that CP may have the effect on the reduction of increase in blood ethanol level after alcohol intake by the marked elevation of plasma alanine and leucine, especially leucine, but neither by the delay of ethanol release from the stomach nor malabsorption of ethanol in the gastrointestinal tracts.

Adult↗

PubMed1997

Hepatic carnitine palmitoyltransferase activity in cattle.

A fluorometric assay for the determination of hepatic carnitine palmitoyltransferase (CPT) activity was slightly modified for use with cattle samples. With this assay, the Km value was 0.56 +/- 0.10 mM with respect to L-carnitine (mean +/- SD, n = 4) and was 9.6 +/- 2.2 microM (n = 3) with respect to palmitoyl-CoA. The average hepatic CPT activity was 33.6 +/- 2.0 mumol CoASH/min/g protein in 38 healthy cattle and was similar in both sexes and among breeds. Hepatic CPT activity showed no correlation with serum phospholipid, free fatty acid, triglyceride or total cholesterol concentrations.

Animals↗

PubMed1997

Three-dimensional analysis of multiple wear vectors in retrieved acetabular cups.

The wear of polyethylene acetabular components is an important issue in total hip arthroplasty. The amount of wear has been measured in many studies, but few have addressed other mechanical aspects of wear in vivo. We used the shadowgraph method to measure the wear vectors in 104 retrieved acetabular cups that had been made by a single manufacturer, and we identified more than one wear vector in thirty-one cups (30 per cent). We hypothesized that the most likely explanation of multiple wear vectors was loosening of the acetabular implant with a change in the orientation of the implant in the pelvis. To test this hypothesis, we estimated the extent of motion of the cup in situ on the basis of differences in angles measured from serial radiographs of sixteen hips. We then used linear transformation of the three-dimensional vectors to compare the wear directions measured in the retrieved implants with the wear directions predicted from the radiographs. The change in wear direction predicted on the basis of in vivo motion of the cup never corresponded to the actual difference between wear vectors in the retrieved implants. Our results suggest that multiple wear vectors may be commonly found in retrieved implants, but loosening of the acetabular cup does not account for the multiple vectors. Additional observations suggest that impingement between the edge of the acetabular cup and the femoral component may be associated with multiple wear vectors. These results have implications for the investigation of the general mechanisms of wear in vivo and suggest that clinical or wear-testing scenarios that assume a single direction of wear may underestimate the over-all amount of volumetric wear.

Equipment Failure Analysis↗

PubMed1997

Transcripts containing the sea urchin retroposon family 1 (SURF1) in embryos of the sea urchin Anthocidaris crassispina.

We isolated two cDNAs, termed D7 and C2 in the present study, from a cDNA library of the 16-cell embryo of the sea urchin Anthocidaris crassispina. The nucleotide sequence was determined completely for D7, and partially for C2. D7 does not have any significant open reading frames. Both D7 and C2 contain a common sequence that is 62% homologous to the sea urchin retroposon family 1 (SURF1). The SURF1 is a short interspersed repetitive element identified from the sea urchin Strongylocentrotus purpuratus, and is reported to be transcribed by RNA polymerase III. The structural feature of D7 and C2, however, suggests that they may be transcribed by RNA polymerase II. RT-PCR analyses revealed that (1) both D7 and C2 transcripts exist as a maternal RNA in the egg, (2) they appear evenly distributed in the 16-cell embryo, and (3) C2 transcripts are present throughout the development up to the gastrula, while D7 transcripts decrease in amount after the early cleavage stage.

Animals↗

PubMed1997

Epidermoid tumor in the sphenoid sinus--case report.

A 36-year-old male presented with a very rare epidermoid tumor in the sphenoid sinus manifesting as paresis of the right sixth cranial nerve and diplopia. Computed tomography and magnetic resonance imaging revealed a mass lesion in the sphenoid sinus expanding to the clivus. The cystic tumor, which contained cholesterin crystals, was extensively removed via the transsphenoidal approach. Histological examination showed epidermoid cell layers, consistent with the diagnosis of epidermoid tumor. Epidermoid tumors should be considered in the differential diagnosis of lesions in the sphenoid sinus.

Adult↗