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Biomedical subjects

E Tsuji

Publications and source records attributed to E Tsuji.

At least 37 records · Page 2Linked to original sources
PubMed1998

Retrieved total hip prostheses: part II. Wear behaviour and structural changes.

Polyethylene cups and femoral heads of retrieved total hip prostheses (Charnley 22 mm stainless steel ball, Bioceram 28 mm alumina ball and Müller 32 mm Co-Cr-Mo alloy ball) were observed by the naked-eye and scanning electron microscopy. Cross-linked cups irradiated with gamma radiation in heavy high doses of 100 Mrad were included. On the weight-bearing surface of the cups non-gamma irradiated, carpet-like conspicuous fine fibres, scratches and fine crevices for the 22 mm ball, scale-like with rough and fine crevices for the 28 mm ball, and scale-like structures and many scratches for the 32 mm ball, were observed, mainly. On the whole, the number of crevices for the 32 mm ball was fewer than that for the 22 and 28 mm balls. The weight-bearing areas of the gamma-irradiated cups presented a clearly outlined pattern, irregularly lined with smooth ripples of about 0.1 microm. The scratching, flaking and delamination, characteristic of non-gamma irradiated polyethylene, were not observed at all. These findings indicate that wear is very small for gamma-irradiated polyethylene. For references, the weight-bearing surfaces of retrieved total knee prostheses were compared.

Journal Article↗
PubMed1998

Retrieved total hip prostheses. Part I: the effects of cup thickness, head sizes and fusion defects on wear.

The effects of polyethylene cup thickness, femoral head sizes (22, 28 and 32 mm) and fusion defects on wear were investigated on retrieved total hip prostheses. When the cup thickness was less than 9 mm, the larger the femoral head, the higher the linear wear rate; however, when the cup thickness was more than 9 mm, the larger the femoral head, the linear wear rate was lower. When the cup thickness was less than 11 mm, the volumetric wear rate increased with increasing size of the femoral head, and when it was more than 11 mm, the volumetric wear rate of the three kinds of the prosthetic cups approached the same values. The wear rate of the cross-linked cups irradiated by 100 Mrad were very low, with no correlation to cup thickness. When the cup thickness was less than 9 mm, the volumetric wear rate tended to increase with increasing number of fusion defects. Large diameter fusion defects diminished the tensile strength.

Journal Article↗
PubMed1998

Genetic analysis of the epithelial sodium channel in Liddle's syndrome.

BACKGROUND: Liddle's syndrome is an autosomal inheritable disorder that causes hypertension due to excess function of sodium channel. OBJECTIVE: To analyze the DNA sequence of the amiloride-sensitive epithelial sodium channel (ENaC) in three patients who had low-renin hypertension with hypokalemia. The patients included a 24-year-old woman and her 20-year-old brother whose mother was hypertensive. The third patient was a 15-year-old girl with no family history of hypertension. METHODS: The DNA sequence of the ENaC was analyzed as follows. Venous blood samples were collected from the patients and total genomic DNA was prepared by standard methods. Specific primers were used for direct polymerase chain reaction; one set of primers for amplifying the C terminus (codon 523-638) of the , subunit of ENaC, and two sets of primers for amplifying the C terminus (codons 525-587 and 568-650) of the y subunit of ENaC. Polymerase chain reaction products were purified and subjected to direct DNA sequence analysis. RESULTS: Direct sequence analysis demonstrated the presence of a single-base substitution in one segment of the 0 subunit of ENaC, a C-T transition that changed the encoded Pro (CCC) at codon 616 to Ser (TCC) in the siblings (cases 1 and 2). In case 3, we found a missense mutation of Pro (CCC) to Leu (CTC) at codon 616. Case 3 is considered to be sporadic, since DNA sequencing of the PY motif of her parents gave normal results. CONCLUSIONS: The DNA sequences of the ENaC in three patients with Liddle's syndrome were analyzed. In one family case, we found a new missense mutation of Pro (CCC) to Ser (TCC) at codon 616 in the 0 subunit of ENaC. A genetic analysis of the amiloride-sensitive epithelial sodium channel is recommended in assessing patients with low-renin, salt-sensitive hypertension whose blood pressure is not responsive to spironolactone treatment.

Adolescent↗
PubMed1998

Function and expression of a novel rat salt-tolerant protein: evidence of a role in cellular sodium metabolism.

Higher dietary salt intake in humans is associated with higher BP, but the BP response to NaCl, so-called salt sensitivity, is heterogeneous among individuals. It has been postulated that modifications in cellular cation metabolism may be related to salt sensitivity in mammalian hypertension. The authors have isolated a novel rat complementary DNA, called salt-tolerant protein (STP), that can functionally complement Saccharomyces cervisiae HAL1, which improves salt tolerance by modulating the cation transport system. On high-salt (8% NaCl) diets, both Dahl salt-sensitive and salt-resistant rats displayed an elevated BP and increased STP mRNA expression. Immunohistochemistry using an anti-rat STP antibody demonstrated the presence of STP immunoreactivity in the proximal tubules. In cells that transiently expressed STP, the intracellular [Na+]/[K+] ratio was higher than that in control cells. STP contains predicted coiled-coil and Src homology 3 domains, and shows a partially high degree of nucleotide identity to human thyroid-hormone receptor interacting protein. These results suggest that STP may play an important role in salt sensitivity through cellular sodium metabolism by mediating signal transduction and a hormone-dependent transcription mechanism.

Amino Acid Sequence↗
PubMed1997

The optimum dose of gamma radiation-heavy doses to low wear polyethylene in total hip prostheses.

Wear volume, surface area and coefficient of friction of UHMWPE cup crosslinked with gamma radiation of 0, 50, 75, 100, 125, 150 and 200 Mrad sliding against an alumina ball were measured using a sphere-on-flat reciprocating type tribology testing machine. The effects of gamma radiation were scarcely observed in coefficient of friction. The coefficient of friction under lubricated (distilled water) and non-lubricated testing conditions was 0.08 to 0.12 and 0.20 to 0.25, respectively. The wear volume of UHMWPE with radiation of 50 Mrad, 75 to 150 Mrad, and 200 Mrad was 70 to 80%, 18 to 25%, and 12 to 15%, respectively, in comparison to non-irradiated specimens. Elongation and tensile strength of UHMWPE with radiation of 100 Mrad decreased to 6%, and 50% of that without radiation, respectively. The hardness increased with increase of the radiation dose. From several kinds of tribological findings, mechanical strength tests, and studies of long-term clinical findings, it is concluded that approximately 200 Mrad is the optimum dose of gamma radiation for clinical use in total hip prostheses.

Journal Article↗
PubMed1997

Rice bran oil and cholesterol metabolism.

A range of human and animal studies have shown that rice bran oil (RBO) is an edible oil of preference for improving serum cholesterol levels and lipoprotein profiles with similarity to the more commonly used vegetable oils such as corn oil and safflower oil. Of particular interest is the observation that blending RBO with safflower oil at a definite proportion (7:3, wt/wt) magnifies the hypocholesterolemic efficacy, compared with the effect of each oil alone. Although the mechanism underlying this effect is not apparent at present, the blending may have a practical significance. The blending effect was reproduced in rats fed a cholesterol-enriched diet, and there was also a decrease in liver cholesterol. The occurrence of peculiar components such as gamma-oryzanol and tocotrienols could be responsible for the hypocholesterolemic effect of RBO.

Animals↗
PubMed1997

Denervation promotes the development of cancer-related lesions in the gastric remnant.

Innervation of the gastric mucosa plays an important role in its defense mechanism. In a previous study, gastrectomy with denervation promoted tumorigenesis in the gastric body in rats after administration of a carcinogenic agent. In this study we investigated the induced gastric mucosal changes from the viewpoint of mucin histochemistry. Gastrectomy with denervation promoted the development of intestinal metaplasia, dysplasia, and carcinoma in the gastric body. Proliferating cell nuclear antigen labeling indexes as a marker for cell kinetics were significantly elevated in the denervated group. Analysis of mucin histochemistry by staining with paradoxical concanavalin A (PCA) and galactose oxidase-Schiff (GOS), which are markers for expression of the gastric phenotype, revealed that these mucins were positive in submucosal adenocystic proliferation and carcinoma at the anastomotic site. Conversely, in the gastric body these mucins disappeared with progression of dysplasia, and carcinoma cells contained neither PCA- nor GOS-positive mucins. These results suggest that there are two different processes of carcinogenesis in the gastric remnant, depending on the location, and that denervation of the remnant gastric mucosa promotes the development of cancer-related lesions in the gastric body.

Animals↗
PubMed1997

Purification and characterization of a kinin- and angiotensin II-forming enzyme in the dog heart.

OBJECTIVE: To purify and characterize a kinin-forming enzyme in the dog heart and to examine the ability of this enzyme to generate angiotensin (Ang) II from Ang I. METHODS: The enzyme was isolated from heart homogenate using a diethylaminoethyl-Sepharose column, an aprotinin affinity column and a wheat germ lectin-Sepharose 6MB column. Kininogenase activity was assessed with a kinin radioimmunoassay after samples had been incubated with bovine low-molecular-mass kininogen at 37 degrees C for 1 h. Ang I-converting activity was assessed by the quantitation of Ang II formed by incubation of the sample with Ang I at 37 degrees C for 3 h, using high performance liquid chromatography. The enzyme was subjected to 12.5% sodium dodecyl sulphate-polyacrylamide gel electrophoresis, stained by Coomassie brilliant blue and transferred electrically to a membrane with glycoprotein staining. RESULTS: The purified enzyme is a glycoprotein with an apparent relative molecular mass of 65 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Its kininogenase activity was approximately 20 micrograms bradykinin/h per mg protein at an optimal pH of 8.0. The enzyme also converted Ang I to Ang II at an optimal pH of 6.5. Its specific activity was approximately 2 micrograms Ang II/h per mg protein. Both activities were inhibited by aprotinin, a tissue kallikrein inhibitor. Western blot analysis using polyclonal antibody against this enzyme demonstrated that this enzyme exists both in the myocardium and in the coronary artery. CONCLUSIONS: The present study showed that the kinin-forming enzyme in the dog heart is a kallikrein-like enzyme that is different from cathepsin D, cathepsin G and chymase. It is also able to Ang I to Ang II. This enzyme might play a role in regulating myocardial perfusion, mainly by generating kinins and in part by forming Ang II.

Angiotensin II↗
PubMed1997

Effect of voluntary exercise on maximal oxygen uptake in young female Fischer 344 rats.

The effect of voluntary exercise on maximal oxygen uptake (VO2 max) was studied in young female Fischer 344 rats. After 10 weeks of wheel-running training, the absolute VO2 max and VO2 max relative to body mass increased without a decline in body mass. The running speed eliciting VO2 max, heart and soleus muscle mass, and succinate dehydrogenase (SDH) activity in the soleus muscle also increased. These results suggest that voluntary exercise is an effective means of increasing the aerobic exercise capacity of young female Fischer 344 rats.

Animals↗
PubMed1997

Particulate bioglass compared with hydroxyapatite as a bone graft substitute.

Bioactive ceramics, notably hydroxyapatite, have been used clinically in various situations in which bone augmentation and restoration are required. Particulate material has been used either alone or in conjunction with freeze dried or autologous bone, with variable clinical success. In this study a bioactive glass, 45S5 Bioglass, has been compared with hydroxyapatite in an animal model to discover whether the 2 major disadvantages of hydroxyapatite may be overcome. These are the difficulty of placing and retaining the particulate in the defect and the length of time needed before full bony restoration is achieved. Bioglass is shown to be easy to manipulate and hemostatic and allows full restoration of bone in 2 weeks, rather than the 12 weeks needed for the particulate hydroxyapatite to produce a comparable response. The Bioglass particulate is used up in the process, and any problems that may be associated with the production of a composite of bone and biomaterial are avoided in the fully restored bone. In any procedure that requires bony augmentation, this rapid response to Bioglass is expected to provide a clinical advantage.

Animals↗
PubMed1996

Molecular cloning of a novel rat salt-tolerant protein by functional complementation in yeast.

To elucidate the genetic basis of salt-sensitivity in mammalian hypertension, we isolated six rat complementary DNAs by functional complementation in yeast. These genes were able to substitute for the salt-tolerant activity of HALI which confers salt tolerance by modulating the cation transport system in yeast. We identified these genes as beta-globin, lambda-crystallin, androgen-regulated protein, mitochondrial cytochrome b, a homologue of infant brain cDNA, and a novel gene, called salt-tolerant protein (STP). STP contains 1964 bp nucleotides and an open reading frame which encodes 496 amino acid residues. Northern blot analysis showed that STP mRNA is expressed in various rat tissues.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1996

Rice bran oil and human health.

The available data in humans suggest that rice bran oil (RBO) is an edible oil of preference for improving plasma lipid and lipoprotein profiles similar to more commonly used vegetable oils. The observation that blending RBO with safflower oil at a specific proportion magnifies the hypocholesterolemic efficacy is of particular interest with regard to utilization of this oil. The occurrence of peculiar components such as gamma-oryzanol and tocotrienols in RBO might be responsible for its hypocholesterolemic effect.

Anticholesteremic Agents↗
PubMed1992

An active-site mutation (Gly633-->Arg) of dipeptidyl peptidase IV causes its retention and rapid degradation in the endoplasmic reticulum.

Dipeptidyl peptidase IV (DPPIV), a serine protease expressed on the cell surface, is deficient in a Fischer rat substrain. Northern blot analysis showed no difference in the size and amount of DPPIV mRNA between normal (344/NC) and deficient (344/CRJ) rats. Cloning and sequencing of DPPIV cDNAs revealed a G to A transition at nucleotide 1897 in the cDNA sequence of 344/CRJ, which leads to substitution of Gly633-->Arg in the active-site sequence Gly629-Trp-Ser-Tyr-Gly633 determined for the wild-type DPPIV [Ogata, S., Misumi, Y., Takami, N., Oda, K., & Ikehara, Y. (1992) Biochemistry 31, 2582-2587]. Pulse-chase experiments with hepatocytes showed that the wild-type DPPIV was initially synthesized as a 103-kDa form with high-mannose-type oligosaccharides, which was processed to a mature form of 109 kDa with the complex type during intracellular transport. In contrast, the mutant DPPIV, although being synthesized as the 103-kDa form, was rapidly degraded without being processed to the mature form. Site-directed mutagenesis of the wild-type and mutant cDNAs and their transfection/expression in COS-1 cells confirmed that the single substitution of Gly633-->Arg is sufficient to cause the rapid intracellular degradation of DPPIV. Immunoelectron-microscopic observations showed that the mutant DPPIV was detectable only in the endoplasmic reticulum (ER), in contrast to the distribution of the wild-type DPPIV in the Golgi complex and on the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Selective cell-surface expression of dipeptidyl peptidase IV with mutations at the active site sequence.

The cell surface expression of dipeptidyl peptidase IV (DPPIV) was examined in COS-1 cells transfected with its cDNA with or without mutations at the active site sequence Gly-Trp-Ser-Tyr-Gly (positions 629-633). Mutants with substitution of Trp630----Glu or Ser631----Ala were expressed on the cell surface as normally as the wild-type DPPIV, although the mutant with Ala631 had no enzyme activity. In contrast, any single substitutions of Gly at positions 629 and 633 resulted in no surface expression of the mutants, which were, instead, detected within the cells. When Tyr632 was substituted, one mutant (Tyr----Phe) was expressed on the surface, whereas the others (Tyr----Gly or Leu) were intracellularly retained. These results indicate that the surface expression of DPPIV is critically influenced by mutations at the active site sequence.

Amino Acid Sequence↗
PubMed1992

Identification of the active site residues in dipeptidyl peptidase IV by affinity labeling and site-directed mutagenesis.

The active site of dipeptidyl peptidase IV (DPPIV) was examined by chemical modification and site-directed mutagenesis. Purified DPPIV was covalently modified with [3H]diisopropyl fluorophosphate (DFP). The radiolabeled DPPIV was digested with lysyl endopeptidase, and the peptides were separated by high-performance liquid chromatography. A single 3H-containing peptide was obtained and analyzed for amino acid sequence and radioactivity distribution. A comparison of the determined sequence with the predicted primary structure of DPPIV [Ogata, S., Misumi, Y., & Ikehara, Y. (1989) J. Biol. Chem. 264, 3596-3601] revealed that [3H]DFP was bound to Ser631 within the sequence Gly629-Trp-Ser-Tyr-Gly633, which corresponds to the consensus sequence Gly-X-Ser-X-Gly proposed for serine proteases. To further identify the essential residues in the active-site sequence, we modified the DPPIV cDNA by site-directed mutagenesis to encode its variants. Expression of the mutagenized cDNAs in COS-1 cells demonstrated that any single substitution of Gly629, Ser631, or Gly633 with other residues resulted in the complete loss of the enzyme activity and DFP binding. Although substitution of Trp630----Glu or Tyr632----Phe caused no effect on the enzyme activity, that of Tyr632----Leu or Gly abolished the activity. These results indicate that the sequence Gly-X-Ser-(Tyr)-Gly is essential for the expression of the DPPIV activity.

Affinity Labels↗
PubMed1992

Effects of fish and safflower oil feeding on subcellular glucose transporter distributions in rat adipocytes.

Effects of fish oil feeding on glucose transport systems and cell size in rat adipocytes were examined and compared with those of safflower oil or carbohydrate feeding under isoenergy intake conditions. Glucose transport activity was assessed by measuring 3-O-methyl-D-glucose transport. The concentration of erythrocyte type glucose transporter (GLUT-1) and muscle/fat type transporter (GLUT-4) was measured by immunoblotting. The amount of each transporter in intact cells was estimated by the amount of transporter and protein of each membrane fraction and by the recovery of marker enzymes. In cells from safflower-fed rats compared with those from carbohydrate-fed rats, insulin-stimulated glucose transport activity per cell decreased to 51% after a 1-wk feeding, and cell size increase became larger with these effects and continued for at least 4 wk. At 1 wk of feeding, GLUT-1 and GLUT-4 per cell in plasma membrane from insulin-treated cells decreased to 62 and 35%, respectively, with concomitant transporter decreases in the low-density microsome fraction. In cells from high-fish oil-fed rats in which two-thirds of safflower oil was replaced by fish oil, when compared with those from safflower oil-fed rats, insulin-stimulated glucose transport activity increased 1.7-fold after 1 wk of feeding with concomitant cellular GLUT-1 and GLUT-4 increases, but its effect declined thereafter. Parallel with this time course, cell size increase was smaller after 1 wk, but this effect also declined thereafter.(ABSTRACT TRUNCATED AT 250 WORDS)

5'-Nucleotidase↗
PubMed1991

Sequence requirements for proteolytic cleavage of precursors with paired basic amino acids.

When expressed in COS cells, human prorenin was secreted into the medium without being processed to an active renin. Co-expression of furin, a mammalian homologue of the yeast KEX2 gene product, did not affect proteolytic processing of prorenin. A mutant proreninR-4 constructed by site-directed mutagenesis of Pro (-4) to Arg was not cleaved by an endoprotease in the COS cell. However, proreninR-4 was detectably cleaved to yield the active renin upon co-transfection with furin DNA, indicating that Arg at position -4 is important for recognition and processing by furin in addition to the absolute requirement for paired basic amino acids. Another mutant precursor in which Leu (+1) of proreninR-4 was replaced with Ser was found to be much more efficiently processed than proreninR-4, regardless of co-expression of furin. The results suggest that not only a basic amino acid at position -4 but also Leu at position +1 significantly affect the processing of prorenin catalyzed by the COS cell endoprotease or furin.

Amino Acid Sequence↗