Biomedical subjects

S Takagi

Publications and source records attributed to S Takagi.

At least 55 records · Page 3Linked to original sources

PubMed2002

Ulcerative colitis is associated with a promoter polymorphism of lipopolysaccharide receptor gene, CD14.

BACKGROUND: Inflammatory bowel disease (IBD) is a multifactorial disease with a significant genetic background. Evidence is accumulating that molecules such as CD14, which interact with luminal bacterial constituents, are involved in the pathogenesis. It has recently been shown that the T allele of the 5'-flanking region of the CD14 gene at position -159 is related to high expression of CD14. In further exploring the genetic background of IBD, we investigated this novel polymorphism of CD14 gene in patients with ulcerative colitis or Crohn disease. METHODS: DNA was obtained from 101 patients with ulcerative colitis, 82 with Crohn disease and 123 healthy controls. All were typed for the promoter polymorphism of the CD14 gene at position -159 by restriction fragment length polymorphism analysis. Serum samples were obtained from 105 healthy controls and serum sCD14 levels were measured. RESULTS: T allele frequencies were 57.4%, 48.2% and 44.7% in ulcerative colitis, Crohn disease and healthy controls, respectively. The T allele and T/T genotype frequencies were significantly higher in ulcerative colitis patients than in healthy controls (P = 0.0074, OR = 1.67, 95% CI = 1.15-2.42, P = 0.022, OR= 1.96 95% CI: 1.10-3.48, respectively). The sCD14 level was significantly higher in TT genotype populations than CC (P = 0.0205). CONCLUSIONS: The promoter polymorphism of the CD14 gene at -159T plays a significant role in regulating the CD14 expression and is positively associated with ulcerative colitis, and this polymorphism may confer a genetic predisposition to ulcerative colitis. The results also support the concept that bacterial constituents may be involved in the pathogenesis of ulcerative colitis.

Adult↗

PubMed2002

Processing and properties of strong and non-rigid calcium phosphate cement.

A calcium phosphate cement (CPC) sets to form hydroxyapatite and has been used in dental and craniofacial applications. However, when CPC was used in periodontal repair, tooth mobility resulted in the fracture and exfoliation of the brittle implants. The aim of this study was to develop CPC-chitosan lactate composites with higher strength and increased strain before failure. It was hypothesized that the incorporation of chitosan lactate would render CPC non-rigid with improved properties. Two-way ANOVA showed significant effects of chitosan lactate and powder:liquid ratio (p < 0.001) on flexural strength, strain-at-peak-load, work-of-fracture, and elastic modulus. At powder:liquid = 2, the strength (mean +/- SD; n = 6) at 20% chitosan lactate was 15.7 +/- 1.3 MPa, higher than 4.9 +/- 1.4 MPa of CPC without chitosan lactate. At powder:liquid = 1, the strain-at-peak-load was 0.2% for CPC without chitosan lactate; it increased to 15.8% for CPC containing 15% chitosan lactate. The work-of-fracture was increased by more than ten times. The novel strong and non-rigid CPC may provide compliance for tooth mobility without fracturing the implant, and may also extend the use of CPC into the repair of larger defects in stress-bearing locations.

Analysis of Variance↗

PubMed2001

Strong and macroporous calcium phosphate cement: Effects of porosity and fiber reinforcement on mechanical properties.

Because of its excellent osteoconductivity and bone-replacement capability, self-setting calcium phosphate cement (CPC) has been used in a number of clinical procedures. For more rapid resorption and concomitant osseointegration, methods were desired to build macropores into CPC; however, this decreased its mechanical properties. The aims of this study, therefore, were to use fibers to strengthen macroporous CPC and to investigate the effects of the pore volume fraction on its mechanical properties. Water-soluble mannitol crystals were incorporated into CPC paste; the set CPC was then immersed in water to dissolve mannitol, producing macropores. Mannitol/(mannitol + CPC powder) mass fractions of 0, 10, 20, 30, and 40% were used. An aramid fiber volume fraction of 6% was incorporated into the CPC-mannitol specimens, which were set in 3 mm x 4 mm x 25 mm molds and then fractured in three-point flexure to measure the strength, work of fracture, and modulus. The dissolution of mannitol created well-formed macropores, with CPC at 40% mannitol having a total porosity of a 70.8% volume fraction. Increasing the mannitol content significantly decreased the properties of CPC without fibers (analysis of variance; p < 0.001). The strength (mean +/- standard deviation; n = 6) of CPC at 0% mannitol was 15.0 +/- 1.8 MPa; at 40% mannitol, it decreased to 1.4 +/- 0.4 MPa. Fiber reinforcement improved the properties, with the strength increasing threefold at 0% mannitol, sevenfold at 30% mannitol, and nearly fourfold at 40% mannitol. The work of fracture increased by 2 orders of magnitude, but the modulus was not changed as a result of fiber reinforcement. A scanning electron microscopy examination of specimens indicated crack deflection and bridging by fibers, matrix multiple cracking, and frictional pullout of fibers as the reinforcement mechanisms. Macroporous CPCs were substantially strengthened and toughened via fiber reinforcement. This may help extend the use of CPCs with macropores for bony ingrowth to the repair of larger defects in stress-bearing locations.

Algorithms↗

PubMed2001

Overproduced p73alpha activates a minimal promoter through a mechanism independent of its transcriptional activity.

p73, the gene for a protein related to the tumor suppressor p53, encodes several variants which bear distinct carboxy-terminal structures as a result of alternative splicing. We and others showed that these splicing variants have different transcriptional effects on promoters with a p53-binding consensus sequence (p53BCS). Here we show that when transiently overexpressed, p73alpha but not p73beta activated several minimal promoters without the p53BCS, while p73gamma and p73epsilon activated them to a much lesser extent than p73alpha, and p53 suppressed the promoters without p53BCS as reported previously. Moreover, the results of RNase protection and RNA transfection assays suggested that this activation occurred at the transcriptional level. Deletion analysis of p73alpha revealed that the transactivation domain of p73 was not involved in this activity and the C-terminal region of p73alpha which is a specific structure of this variant was essential, suggesting that this phenomenon occurs independent of the transactivation activity of p73alpha and that the C-terminal extension of p73alpha may affect the basal level of transcription.

Binding Sites↗

PubMed2001

Transcriptional activities of p73 splicing variants are regulated by inter-variant association.

p73 has been identified as a gene that encodes a protein with significant identity with the tumour suppressor p53. The main structural difference between p73 and p53 is the additional C-terminal region of p73. Six isoforms of p73 with differing C-terminal structures, alpha, beta, gamma, delta, epsilon and xi, have been reported. These variants differ in transcriptional activity on p53-responsive promoters. Here we report a possible mechanism of transcriptional activation by p73 splicing variants. C-terminal deletion mutants of p73 alpha showed a significantly higher level of transcriptional activity than wild-type p73 alpha, suggesting that the C-terminal structure of p73 alpha functions to repress the transcriptional activity of p73 alpha. The results of immunoprecipitation assays and two-hybrid assays in mammalian cells showed that the p73 variants interacted with each other, but not with p53. The transcriptional activity of p73 beta was reduced by co-expression with either p73 alpha or p73 epsilon, which bears an identical C-terminal structure to p73 alpha. Co-expression of the C-terminal portion of p73 alpha or p73 epsilon with p73 beta also resulted in reduced transcriptional activity. Moreover, we observed that the level of endogenous p21 protein induced by p73 beta was decreased by co-expression of full-length p73 epsilon or the C-terminal region of p73 alpha or p73 epsilon. These observations suggest that p73-mediated gene expression is regulated by the interactions of p73 splicing variants in the cell.

Animals↗

PubMed2001

p73beta, a variant of p73, enhances Wnt/beta-catenin signaling in Saos-2 cells.

The Wnt/beta-catenin pathway and p53 are very common targets for genetic alterations in colorectal cancer, and relationships between them have been reported. Here, we describe the relation between Wnt/beta-catenin signaling and the p53-related gene p73. p73, but not p53, activated a promoter containing the Tcf-binding sequence in Saos-2 cells, and the degree of activation was positively correlated with that on a p53-responsive promoter. Moreover, p73beta enhanced Wnt/beta-catenin signaling synergistically with Wnt-3a or exogenously expressed beta-catenin, unlike p53, and the enhancement was not caused by the accumulation of beta-catenin. These results show that the effects of p73 on Wnt/beta-catenin signaling differ from those of p53.

Base Sequence↗

PubMed2001

Morphological and phase characterizations of retrieved calcium phosphate cement implants.

A self-hardening calcium phosphate cement (CPC), consisting of equimolar amounts of tetracalcium phosphate and dicalcium phosphate anhydrous, hardens when mixed with water and forms a resorbable hydroxyapatite (HA) as the end-product. The objective of this study was to investigate the changes of the phase and morphology of the CPC during hardening and aging under in vivo conditions. CPC samples retrieved 12 h after hardening in vivo had already contained carbonated HA (type B), even though the initial cement mixture did not contain carbonate as one of the solid components. The mass fraction of carbonate in the 12-h sample was about 1%. The results suggested that under in vivo conditions carbonate is readily available and this allows formation of carbonated HA in favor of carbonate-free HA. The carbonate content of the CPC samples retrieved 3 months after implantation was similar to that of the 12-h samples, and the exterior surfaces of the 3-month samples appeared less crystalline than that of the 12-h samples.

Animals↗

PubMed2001

Quantification of suppression of bitterness using an electronic tongue.

Phospholipids, such as phosphatidic acid, suppress bitter taste without affecting other taste qualities. In the present study, we detected and quantified this suppression effect with an electronic tongue whose transducer is composed of several kinds of lipid/polymer membranes with different characteristics. We measured a phospholipid cocktail and various kinds of taste substances with five basic taste qualities. The responses to quinine hydrochloride and L-tryptophan, which have a bitter taste, were reduced as the phospholipid concentration was increased, and the responses to the other taste substances were not affected by the phospholipids, as with the human sensation test. Furthermore, the change of bitter intensity caused by phospholipid was quantified by principal component analysis and the tau scale, which expresses the relationship between taste intensity and taste substance concentration. The results are compared with those of the human sensory test and discussed.

Computer Simulation↗

PubMed2001

Basic fibroblast growth factor up-regulates the surface expression of complement receptors on human monocytes.

OBJECTIVE AND DESIGN: To clarify the possible involvement of basic fibroblast growth factor (b-FGF) in inflammation, we examined the effect of b-FGF on the surface expression of complement receptors (CR) on human monocytes in vitro. MATERIALS AND METHODS: Heparinized venous blood was obtained from healthy adult donors. The surface expression of CR on blood monocytes was determined by two-color immunofluorescent staining using flow cytometry and monoclonal antibodies. A standard whole blood lysis technique was used to avoid any in vitro manipulation that would activate monocytes. RESULTS: b-FGF increased the expression of CR3 on monocytes in a dose- and time-dependent manner. The b-FGF concentrations used were up to 100 ng/ml. The values of mean fluorescence intensity (MFI) of CR3 expression on unstimulated monocytes were 12.6+/-1.3 (n = 3), whereas those on b-FGF-stimulated monocytes were 59.2+/-7.1 (n = 3). b-FGF also up-regulated the expression of CR1 on monocytes in a dose- and time-dependent manner. The MFI values of CR1 expression on unstimulated monocytes were 2.5+/-0.1 (n = 3), whereas those on b-FGF-stimulated monocytes were 11.1+/-0.6 (n=3). The magnitude of CR1 expression by monocytes was significantly smaller than that of CR3 expression. The maximal stimulatory effect of b-FGF on monocytes was observed using greater than 25 ng/ml of b-FGF and 90-120 min incubation period. CONCLUSION: b-FGF may participate in the inflammatory process by modulating the CR expression on blood monocytes.

Adult↗

PubMed2001

A novel thermostable branching enzyme from an extremely thermophilic bacterial species, Rhodothermus obamensis.

A branching enzyme (EC 2.4.1.18) gene was isolated from an extremely thermophilic bacterium, Rhodothermus obamensis. The predicted protein encodes a polypeptide of 621 amino acids with a predicted molecular mass of 72 kDa. The deduced amino acid sequence shares 42-50% similarity to known bacterial branching enzyme sequences. Similar to the Bacillus branching enzymes, the predicted protein has a shorter N-terminal amino acid extension than that of the Escherichia coli branching enzyme. The deduced amino acid sequence does not appear to contain a signal sequence, suggesting that it is an intracellular enzyme. The R. obamensis branching enzyme was successfully expressed both in E. coli and a filamentous fungus, Aspergillus oryzae. The enzyme showed optimum catalytic activity at pH 6.0-6.5 and 65 degrees C. The enzyme was stable after 30 min at 80 degrees C and retained 50% of activity at 80 degrees C after 16 h. Branching activity of the enzyme was higher toward amylose than toward amylopectin. This is the first thermostable branching enzyme isolated from an extreme thermophile.

1,4-alpha-Glucan Branching Enzyme↗

PubMed2001

alpha-1-Antichymotrypsin gene A1252G variant (ACT Isehara-1) is associated with a lacunar type of ischemic cerebrovascular disease.

alpha-1-Antichymotrypsin (ACT) is a plasma protease inhibitor belonging to the serpine superfamily; it has many functions. and thus qualitative change in ACT is likely to result in specific diseases. We previously reported a variant AACT (ACT Isehara-1, Met389Val, A1252G) in patients with ischemic cerebrovascular disease (CVD). The present study was designed to examine the association of the variant with ischemic CVD, in 87 patients and 397 age-matched controls. We found that the frequency of the A1252G variant (ACT Isehara-1) was higher in the group with ischemic CVD than in the control group (P = 0.0397), which appeared to be independent of known risk factors. We subdivided the CVD group into lacunar and atherothrombotic subgroups. Further analysis by subtype of ischemic CVD showed an association of ACT Isehara-1 with lacunar infarction (P = 0.0036). These results suggest that ACT lsehara-1 is a new genetic risk factor for ischemic CVD, especially lacunar-type infarction, in Japan.

Adult↗

PubMed2001

Efficacy of a 14-day course of oral ciprofloxacin therapy for acute uncomplicated pyelonephritis.

This study aimed to evaluate the efficacy and safety of oral antibacterial treatment with fluoroquinilone for acute uncomplicated pyelonephritis Thirteen female patients with acute uncomplicated pyelonephritis were treated with oral fluoroquinilone (ciprofloxacin; CPFX). They received 200 mg of the drug three times a day while febrile (3-5 days). Once they become afebrile, the same dose of the drug, given twice a day, was given for another 9-11 days. The mean duration of the course of CPFX was 14 days. Symptoms were evaluated, and laboratory examinations, including urine culture and measurement of the minimal inhibitory concentration (MIC) of CPFX were conducted before treatment, and 3, 7, 14, 21, and/or 28 days after the initiation of the treatment. Of the 13 patients, only 5 needed to be hospitalized, and the period of hospitalization was only a few days. On the 14th day after the commencement of treatment, bacteriologic and clinical cure rates were 100%. Escherichia coli was the most common uropathogen, being isolated from the urine of 8 patients. No clinical relapse of the disease was found during a follow-up period of up to 4 weeks. The patients tolerated the drug well without developing any serious adverse effects. Oral antimicrobial chemotherapy with fluoroquinolone, given on an outpatient or short-term hospitalization basis, achieved satisfactory bacteriological and clinical outcomes in the treatment of acute uncomplicated pyelonephritis. This treatment regimen is indicated for patients with this disease who are not in a serious condition with complications such as shock.

Acute Disease↗

PubMed2001

Reassessment of monoethylglycinexylidide as preoperative liver function test in a rat model of liver cirrhosis and man.

It is known that lidocaine is rapidly metabolized by the hepatic cytochrome P-450 system to form monoethylglycinexylidide (MEGX), its primary metabolite. We analyzed serum MEGX levels experimentally and clinically by fluorescent polarization immunoassay to reassess preoperative liver microsome functions. EXPERIMENTAL STUDY: Liver cirrhosis was produced in rats by intra-abdominal injection of thioacetamide. MEGX, indocyanine green test (ICG), and liver biochemical variables were measured periodically. Then, survival rates were assessed after the rats received a 70% hepatectomy. CLINICAL STUDY: MEGX levels were measured in various human patients with chronic hepatitis or liver cirrhosis who underwent hepatectomy. Serum MEGX levels significantly dropped and ICG levels significantly rose with macroscopic and histologic progression of liver cirrhosis in rats. The MEGX levels correlated closely with albumin levels and ICG. Preoperative MEGX and ICG levels of the mortal group of rats differed significantly from those of the survival group with 70% hepatectomy. Furthermore, 100% of the rats with MEGX levels above 40 ng/ml and ICG levels below 1.0%. In the clinical study, MEGX levels were significantly lower in patients with chronic hepatitis or liver cirrhosis than in healthy volunteers and correlated significantly with liver function tests such as albumin, Fischer's ratio, prothrombin time, hepaplastin and ICG. A significant difference was found in MEGX levels between patients receiving lobectomy and those receiving subsegmentectomy or partial hepatectomy. All patients tolerated their operations. Our data indicate that the MEGX test combined with ICG test and Child-Pugh classification is a better predictor of residual liver reserve capacity, and the analysis of hepatic MEGX formation might prove useful for rapid and reliable assessment liver function and choice of surgical treatment.

Alanine Transaminase↗

PubMed2001

Spermatogonial proliferation and apoptosis in hypospermatogenesis associated with nonobstructive azoospermia.

OBJECTIVE: To provide evidence that a pathological process in spermatogonial proliferation and apoptosis may participate in developing hypospermatogenesis of infertile men. DESIGN: Case-controlled retrospective analysis. SETTING: University-based male infertility clinic. PATIENT(S): Thirty-four patients with idiopathic hypospermatogenesis. INTERVENTION(S): Collecting blood samples for measurement of hormones and performing testicular biopsy for assessment of spermatogenesis. MAIN OUTCOME MEASURE(S): The expression of proliferating cell nuclear antigen (PCNA) of spermatogonia and the frequency of apoptosis of spermatogonia demonstrated by the in situ DNA 3'-end-labeling method were investigated to determine the degree of cell degeneration. RESULT(S): We could classify 34 infertile patients into four subgroups according to spermatogonial proliferation and differentiation. No significant difference in the expression of PCNA was demonstrated between these four groups and the control group. In all groups, the balance of spermatogonial proliferation (PCNA-positive rate) to apoptosis was significantly lower than that of the control group. CONCLUSION(S): It was demonstrated that accelerated apoptosis, rather than proliferative dysfunction in the mitotic phase, may induce the decreased number of spermatogonia in hypospermatogenesis. These findings suggest that disorders of the control and regulation of apoptosis may participate in the pathogenesis of idiopathic hypospermatogenesis.

Adult↗

PubMed2001

Real-time measurement of low-energy-range neutron spectra on board the space shuttle STS-89 (S/MM-8).

We have developed a real-time, Bonner Ball-type (neutron energy range is from thermal to 15 MeV) neutron spectral measurement system (Bonner Ball Neutron Detector (BBND)) for use on board the International Space Station (ISS). From measurements taken inside STS-89 (S/MM-8), we successfully distinguished neutrons from protons and other particles in a mixed radiation field; a task hitherto considered difficult. Although the experimental period was short, only 3.5 days (January 24-27, 1998), we were able to obtain energy spectral data and the Earth's neutron dose-equivalent map for the ISS orbital conditions (altitude 400 km, orbit inclination angle 51.6 degrees). A method for calculating the neutron energy spectrum and compensating for the particle interaction with the sensors is also described in detail.

Aluminum↗

PubMed2001

Efficiency of rice bran for removal of organochlorine compounds and benzene from industrial wastewater.

Rice bran was found to effectively adsorb several organic compounds, such as dichloromethane, chloroform, carbon tetrachloride, trichloroethylene, tetrachloroethylene, and benzene. Equilibrium adsorption isotherms conformed to the Freundlich type (log-log linear). The adsorption of dichloromethane and chloroform by rice bran was observed over the range of pH 1-11. Therefore, rice bran is applicable for treatment of wastewater over a wide pH range. Dichloromethane was successfully removed from water samples with an average removal efficiency of 70% after 60 min when rice bran was added to water samples containing from 0.006 to 100 mg/L dichloromethane. The removal of these organochlorine compounds and benzene by rice bran was attributed to the uptake by intracellular particles called spherosomes. Here, we report the results of a fundamental study of the efficiency of rice bran for removal of organochlorine compounds and benzene using a batch system on the laboratory scale, and describe elucidation of the mechanism of removal of these compounds by rice bran.

Adsorption↗

PubMed2001

Formation of macropores in calcium phosphate cement implants.

A calcium phosphate cement (CPC) was shown to harden at ambient temperatures and form hydroxyapatite as the only end-product. Animal study results showed that CPC resorbed slowly and was replaced by new bone. For some clinical applications, it would be desirable to have macropores built into the CPC implant to obtain a more rapid resorption and concomitant osseointegration of the implant. The present study investigated the feasibility of a new method for producing macropores in CPC. Sucrose granules, NaHCO3, and Na2HPO4 were sieved to obtain particle sizes in the range of 125 microm to 250 microm. The following mixtures of CPC powder (an equimolar mixture of tetracalcium phosphate, Ca4(PO4)2O, and dicalcium phosphate anhydrous, CaHPO4) and one of the above additive granules were prepared: control-no additive; mixture A-0.25 mass fraction of sucrose; mixture B-0.25 mass fraction of NaHCO3; mixture C-0.25 mass fraction of Na2HPO4, and mixture D-0.33 mass fraction of Na2HPO4. Cement samples were prepared by mixing 0.3 g of the above mixtures with 0.075 ml of the cement liquid (1 mol/l Na2HPO4). After hardening, the specimens were placed in water for 20 h at about 60 degrees C to completely dissolve the additive crystals. Well-formed macropores in the shapes of the entrapped crystals were observed by scanning electron microscope (SEM). The macroporosities (mean+/-standard deviation; n = 6) expressed as volume fraction in % were 0, 18.9 +/- 1.7, 26.9 +/- 1.6, 38.3 +/- 4.4 and 50.3 +/- 2.7 for the control, A, B, C and D, respectively. The diametral tensile strengths (mean+/-standard deviation; n = 3) expressed in MPa were 10.1 +/- 0.7, 3.7 +/- 0.3, 2.4 +/- 0.2, 1.5 +/- 0.5 and 0.4 +/- 0.1, respectively, for the five groups. The results showed that macropores can readily be formed in CPC implants with the use of water-soluble crystals. The mechanical strength of CPC decreased with increasing macroporosity.

Journal Article↗

PubMed2001

Survival of memory T cells specific for Japanese cypress pollen allergen is maintained by cross-stimulation of putative pectate lyases from other plants.

In view of recent studies on the mechanisms of the survival of peripheral memory T cells, we tested the biologic role of pectate lyase, a pectin-degrading enzyme, as the cross-reactive antigen required for the recurring survival signals for human T cells specific for Cha o 1, a pollen allergen molecule of the Japanese cypress. We determined a 16-mer epitope peptide for the T-cell clone, and prepared synthetic oligopeptides of homologous regions in putative pectate lyase of other plants. Of these homologous peptides, ZePel (Zinnia elegans), ban 17 (banana), and Amb a 1.1 (short ragweed) induced strong proliferative responses of the Cha o 1-specific T-cell clone in vitro. In addition, suboptimal doses of peptide homologs derived from banana and short ragweed enhanced the survival potency of this T-cell clone without detectable proliferative responses to the peptides. When there was no antigen stimulation, the T-cell clone decreased in viable cell number and lost antigen-specific proliferation activity on day 6 during in vitro incubation. On the other hand, T-cell clones incubated with these survival-inducing peptides maintained proliferative activity to Cha o 1 even on day 9. Serum derived from the donor patient did not contain detectable levels of IgE specific to banana or short ragweed by CAP-RAST. These results show that human T cells specific for pollen allergen seem to use cross-reactive pectate lyase peptides to deliver survival signals even in the absence of pollen allergen, and memory T cells maintained in such a manner might be functioning at the onset of allergic pollinosis, although pollen allergens are seasonal.

Allergens↗