Biomedical subjects

K Taira

Publications and source records attributed to K Taira.

At least 109 records · Page 6Linked to original sources

PubMed2000

Tubulointerstitial nephritis associated with Legionnaires' disease.

A 47-year-old man was admitted to our hospital for community-acquired pneumonia complicated with acute renal failure. Legionella pneumophila serogroup type 1 was grown in BCYE (buffered charcoal yeast extract) agar for sputum culture. Although his respiratory illness responded to intravenous erythromycin therapy, renal failure worsened and necessitated hemodialysis. Renal biopsy showed profound tubulointerstitial nephritis. After initiation of steroid therapy his renal function improved and he was discharged thereafter. These findings suggest that in Legionnaires' disease with acute renal failure, tubulointerstitial nephritis should also be considered and steroid therapy may be an effective modality for the renal complication.

Acute Kidney Injury↗

PubMed2000

Long-term (14 years) effect of LDL apheresis on obstructive changes in aortocoronary saphenous-vein bypass grafts in a case of heterozygous familial hypercholesterolemia with the LDL receptor proline664 to leucine mutation.

A 61-year-old Japanese woman with heterozygous familial hypercholesterolemia (FH), type 2 diabetes mellitus and coronary artery disease underwent coronary artery bypass grafting (CABG) utilizing a saphenous vein graft at the age of 46, in June 1984, 6 months before low density lipoprotein (LDL) apheresis was started. She had received LDL apheresis every two weeks, along with combined drug treatment since the age of 47 (December 1984). She had bilateral xanthelasma and Achilles tendon xanthomas. Her fasting baseline serum total cholesterol and triglyceride level were 464 mg/dl and 57 mg/dl, respectively at the age of 47 when she visited our hospital for the first time. Analysis of the genomic DNA from the patient revealed heterozygous amino acid substitution of Leu for Pro664 in the LDL receptor gene. She was diagnosed as type 2 diabetes mellitus at the age of 53. Combined treatment in the steady state yielded a pretreatment LDL cholesterol level of 230+/-14 mg/dl and a posttreatment level of 57+/-7.6. All grafts were widely patent after as long as 14 years since CABG, suggesting that LDL apheresis combined with drug therapy is highly effective in preventing the occlusion of bypass grafts in a patient with heterozygous FH and type 2 diabetes mellitus.

Aorta↗

PubMed2000

[Clinical study on risk management for dental implant treatment--Part 1. Clinical retrospective study on the medically compromised patients at clinic for oral implant].

A retrospective study on medically compromised patients was made using 1,000 outpatients who visited the Clinic for Oral Implant, University Hospital, Faculty of Dentistry, Tokyo Medical and Dental University between April 1995 and June 1998. The results were as follows: 1. 35.3% (353 patients: 140 males and 213 females) of the outpatients were medically compromised. 2. The greatest number of medically compromised patients was in the 50-59 age group (118 cases), followed by those in the 40-49 and 60-69 age groups. 3. The highest ratio of medically compromised patients was in the 60-69 age group (48.2%), followed by those in the 70-79 and 50-59 age groups. 4. Among the 353 patients, 96 (27.2%) underwent surgical treatment such as insertion of implant (68 cases), removal of implant, extraction of tooth, and free gingival graft. 5. Among the 68 patients who underwent insertion of implant, in a classification by type of disease, the patients with cardiovascular diseases were the most numerous (33.9%), followed by metabolic and digestive tract diseases. 6. All surgical treatments of implant insertion were performed under local anesthesia, while monitoring cardiac and respiratory function, and SpO2. Among the 68 patients, 9 underwent operation under intravenous sedation and 2 under nitrous oxide inhalation sedation. All 11 patients had hypertension. The results suggested that identification of preoperative risk factors, precise recognition of general condition, and establishment of control system are important to manage medically compromised patients for dental implant treatment.

Adult↗

PubMed2000

Combined endoscopic and surgical treatment for multiple polyps of the small intestine in Peutz-Jeghers syndrome: a case report.

Combined endoscopic and surgical treatment in a 14-year-old girl with Peutz-Jeghers syndrome is reported herein. The patient was diagnosed with Peutz-Jeghers syndrome because of mucocutaneous pigmentation and hamartomas of the small intestine at 10 years of age, when she underwent an emergency laparotomy for an intussusception of the small intestine. Since this diagnosis, she has undergone follow-up, and barium radiologic and endoscopic studies have shown multiple polyps of various sizes from the stomach throughout the small intestine and to the colon. This time, with the use of combined endoscopic and surgical treatment for polyps of the small intestine, 26 polyps were removed endoscopically by performing only one enterotomy. This combined technique may allow for a longer interval between laparotomies, therefore reducing the complications associated with multiple laparotomies and resections.

Adolescent↗

PubMed2000

Two-phase partition method for simulating a biological system at an extremely high speed.

To accelerate the calculation speed for simulating a biological system, we proposed a novel simulation method, the two-phase partition method, which calculated molecular processes at a higher speed than any other proposed method. This method divides a biological system, which can be described by chemical reaction equations, into two-phases: the binding and reaction phases. We demonstrated the capability of the two-phase partition method to simulate a complex biological system at an extremely high speed and clarified the accuracy of the simulation. The two-phase partition method is very useful for simulating complex interactions among proteins and DNAs.

Ammonia↗

PubMed1999

Specificity of novel allosterically trans- and cis-activated connected maxizymes that are designed to suppress BCR-ABL expression.

Chronic myelogenous leukemia (CML) is associated with the presence of the Philadelphia chromosome, which is generated by the reciprocal translocation of chromosomes 9 and 22. In the case of L6 (b2a2) mRNA, it is difficult to cleave the abnormal mRNA specifically because the mRNA includes no sequences that can be cleaved efficiently by conventional hammerhead ribozymes near the BCR-ABL junction. We recently succeeded in designing a novel maxizyme, which specifically cleaves BCR-ABL fusion mRNA, as a result of the formation of a dimeric structure. As an extension of our molecular engineering of maxizymes, as well as to improve their potential utility, we examined whether an analogous conformational change could be induced within a single molecule when two maxizymes were connected via a linker sequence. An active conformation was achieved by binding of the construct to the BCR-ABL junction in trans, with part of the linker sequence then acting as an antisense modulator in cis (within the complex) to adjust the overall structure. Results of studies in vitro in the presence of cetyltrimethylammonium bromide (CTAB) (but not in its absence) suggested that a certain kind of connected maxizyme (cMzB) might be able to undergo a desired conformational change and, indeed, studies in vivo confirmed this prediction. Therefore, we successfully created a fully functional, connected maxizyme and, moreover, we found that the activity and specificity of catalytic RNAs in vivo might be better estimated if their reactions are monitored in vitro in the presence of CTAB.

Allosteric Regulation↗

PubMed1999

Observation of Multi-TeV Gamma Rays from the Crab Nebula using the Tibet Air Shower Array.

The Tibet experiment, operating at Yangbajing (4300 m above sea level), is the lowest energy air shower array, and the new high-density array constructed in 1996 is sensitive to gamma-ray air showers at energies as low as 3 TeV. With this new array, the Crab Nebula was observed in multi-TeV gamma-rays and a signal was detected at the 5.5 sigma level. We also obtained the energy spectrum of gamma-rays in the energy region above 3 TeV which partially overlaps those observed with imaging atmospheric Cerenkov telescopes. The Crab spectrum observed in this energy region can be represented by the power-law fit dJ&parl0;E&parr0;&solm0;dE=&parl0;4.61+/-0.90&parr0;x10-12&parl0;E&solm0;3 TeV&parr0;-2.62+/-0.17 cm-2 s-1 TeV-1. This is the first observation of gamma-ray signals from point sources with a conventional air shower array using scintillation detectors.

Journal Article↗

PubMed1999

An investigation of the nature and function of module 10 in a family F/10 xylanase FXYN of Streptomyces olivaceoviridis E-86 by module shuffling with the Cex of Cellulomonas fimi and by site-directed mutagenesis.

Although the amino acid homology in the catalytic domain of FXYN xylanase from Streptomyces olivaceoviridis E-86 and Cex xylanase from Cellulomonas fimi is only 50%, an active chimeric enzyme was obtained by replacing module 10 in FXYN with module 10 from Cex. In the family F/10 xylanases, module 10 is an important region as it includes an acid/base catalyst and a substrate binding residue. In FXYN, module 10 consists of 15 amino acid residues, while in Cex it consists of 14 amino acid residues. The Km and kcat values of the chimeric xylanase FCF-C10 for PNP-xylobioside (PNP-X2) were 10-fold less than those for FXYN. CD spectral data indicated that the structure of the chimeric enzyme was similar to that of FXYN. Based on the comparison of the amino acid sequences of FXYN and Cex in module 10, we constructed four mutants of FXYN. When D133 or S135 of FXYN was deleted, the kinetic properties were not changed from those of FXYN. By deletion of both D133 and S135, the Km value for PNP-X2 decreased from the 2.0 mM of FXYN to 0.6 mM and the kcat value decreased from the 20 s(-1) of FXYN to 8.7 s(-1). Insertion of Q140 into the doubly deleted mutant further reduced the Km value to 0.3 mM and the kcat value to 3.8 s(-1). These values are close to those for the chimeric enzyme FCF-C10. These results indicate that module 10 itself is able to accommodate changes in the sequence position of amino acids which are critical for enzyme function. Since changes of the spatial position of these amino acids would be expected to result in enzyme inactivation, module 10 must have some flexibility in its tertiary structure. The structure of module 10 itself also affects the substrate specificity of the enzyme.

Amino Acid Sequence↗

PubMed1999

Stable gene expression with VSV-G pseudotyped-retrovirus vector in the rat liver.

BACKGROUND: Pseudotyped-retrovirus-mediated gene transfer to the regenerating rat liver was investigated in vivo and the findings were compared with those for retrovirus-mediated gene transfer. MATERIALS AND METHODS: Four weeks prior to gene transfer, the spleen was transpositioned to the left subcutaneous position to develop a port-splenic shunt. Twenty-four hours after a partial hepatectomy (68%) was performed, the liver was perfused in situ and kept in contact with either a pseudotyped-retrovirus vector encoding LacZ (7 x 10(7) cfu/ml, Group 1) or a retrovirus vector encoding LacZ (1 x 10(4) cfu/ml, Group 2) for 30 min. The animals were sacrificed at various points after gene transfer, and X-gal staining, reversed polymerase chain reaction (RT-PCR), and ONPG assay were performed to detect the transferred LacZ cDNA. RESULTS: In X-gal staining, the transferred LacZ cDNA started to show a strong beta-galactosidase activity in 30 to 50% of the hepatocytes at 3 days after gene transfer. Positive staining continued to be recognized until 28 days with a slight decrease in its intensity thereafter. On the other hand, Group 2 animals showed weak staining, which was observed in about 10 to 15% of the hepatocytes from 3 days after gene transfer and then decreased thereafter. In RT-PCR, positive mRNA of LacZ was detected constitutively until 28 days after gene transfer in Group 1, whereas two-thirds of the samples showed a negative band in Groups 2 at 3 days after gene transfer. CONCLUSION: In conclusion, the pseudotyped-retrovirus vector was useful in establishing a stable and strong expression of the in vivo gene transfer, while targeting the regenerating liver.

Animals↗

PubMed1999

Significant enhancement in the binding of p-nitrophenyl-beta-D-xylobioside by the E128H mutant F/10 xylanase from Streptomyces olivaceoviridis E-86.

Mutagenesis studies were carried out to examine the effects of replacement of either the nucleophile Glu-236 or the acid/base Glu-128 residue of the F/10 xylanase by a His residue. To our surprise, the affinity for the p-nitrophenyl-beta-D-xylobioside substrate was increased by 10(3)-fold in the case of the mutant E128H enzyme compared with that of the wild-type F/10 xylanase. The catalytic activity of the mutant enzymes was low, despite the fact that the distance between the nucleophilic atom (an oxygen in the native xylanase and a nitrogen in the mutant) and the alpha-carbon was barely changed. Thus, the alteration of the acid/base functionality (Glu-128 to His mutation) provided a significantly favorable interaction within the E128H enzyme/substrate complex in the ground state, accompanying a reduction in the stabilization effect in the transition state.

Disaccharides↗

PubMed1999

CTAB-mediated enrichment for active forms of novel dimeric maxizymes.

We demonstrated previously that shortened forms of (stem II-deleted) hammerhead ribozymes with low intrinsic activity form very active dimers with a common stem II (very active short ribozymes capable of forming dimers were designated maxizymes). As a result of such a dimeric structure, heterodimeric maxizymes are potentially capable of cleaving a substrate at two different sites simultaneously. In this case, active heterodimers are in equilibrium with inactive homodimers. Longer forms of common stem II can lead to enrichment of the active heterodimers in vitro. In this study, we investigated whether the cationic detergent CTAB, which is known to enhance strand displacement of nucleic acids, might inhibit the dimerization of maxizymes. Significantly, under all conditions examined, CTAB instead enhanced the activity of a variety of maxizymes, with the extent of enhancement depending on the conditions. The activity of our least stable, least active maxizyme was enhanced 100-fold by CTAB. The strand displacement activity of CTAB thus appears to enhance the conversion of alternative conformations of inactive maxizymes, with intra- and inter-molecular hydrogen bonds, to active forms. Thus, our smallest maxizyme can also be considered a potential candidate for a gene-inactivating agent in vivo, in view of the fact that various facilitators of strand displacement reactions are known to exist in vivo (indeed, a separate experiment in cell culture supported the conclusion that our smallest maxizyme is a good gene-inactivating agent). Although activities of ribozymes in vitro do not necessarily reflect their activities in vivo, our findings suggest that the activity of ribozymes in vivo can be better estimated by running ribozyme kinetics in the presence of CTAB in vitro.

Base Sequence↗

PubMed1999

tRNAVal-heterodimeric maxizymes with high potential as geneinactivating agents: simultaneous cleavage at two sites in HIV-1 Tat mRNA in cultured cells.

It has been demonstrated that shortened forms of (stem II-deleted) hammerhead ribozymes with low intrinsic activity form very active dimers with a common stem II (very active short ribozymes capable of forming dimers were designated maxizymes). Intracellular activities of heterodimeric maxizymes and conventional ribozymes, under the control of a human tRNAVal-promoter, were compared against the cleavage of HIV-1 tat mRNA. The pol III-driven maxizymes formed very active heterodimers, and they successfully cleaved HIV-1 tat mRNA in mammalian cells at two sites simultaneously. The cleaved fragments were identified directly by Northern blotting analysis. Despite the initial concerns that a complicated dimerization process and formation of inactive homodimers were involved in addition to the process of association with the target, the overall intracellular activities of tRNAVal-driven maxizymes were significantly higher in mammalian cells than those of two sets of independent, conventional hammerhead ribozymes that were targeted at the same two sites within HIV-1 tat mRNA. Because the tRNAVal-driven maxizymes tested to date have been more effective than tRNAVal-driven "standard" hammerhead ribozymes, the tRNAVal-driven heterodimeric maxizymes appear to have potential utility as gene-inactivating agents.

Animals↗

PubMed1999

Protective effects of ulinastatin against ischemia-reperfusion injury.

We investigated the protective effect of urinary trypsin inhibitor (ulinastatin: UTI) in vitro, in relation to the neutrophil activity in hepatic ischemia/reperfusion (I/R) injury. The rat liver was removed and preserved in cold Ringer's lactate solution for 60 min, followed by 120 min of reperfusion with oxygenated perfusate. The rats were divided into four groups (n = 8 in each group). The livers were perfused with Krebs-Henseleit (K-H) solution containing no additives in group 1, 50,000 U/kg of UTI in group 2, 3.5 x 10(6) of neutrophils in group 3, and both neutrophils and UTI in group 4. In group 3, the AST and ALT levels were always higher than those in other three groups at any point evaluated (P < 0.01) and the LDH levels were observed to be significantly higher than those in other three groups at 0, 5, 10, 60, and 90 min after reperfusion (P < 0. 01). These increase were suppressed by additional pretreatment with UTI in group 4. The bile flow during reperfusion was significantly suppressed in group 3 compared to that of group 4, at both 30 (P < 0. 01) and 60 (P < 0.05) min after reperfusion. The MPO activity after reperfusion in group 3 also significantly increased compared to other three groups (P < 0.01). These data thus suggest that UTI ameliorated the ischemia/reperfusion injury in vitro by inhibiting of neutrophil accumulation in the postischemic liver.

Animals↗

PubMed1999

A novel frameshift mutation in exon 6 (the site of Asn 291) of the lipoprotein lipase gene in type I hyperlipidemia.

A new heterozygous lipoprotein lipase gene defect has been identified in a type I hyperlipidemic patient at the position of notable amino acid Asn 291. The patient is a 33-year-old male. His body mass index (BMI) was 18.5 kg/m2. The total cholesterol (TC), triglycerides (TG) and high density lipoprotein-cholesterol (HDL-C) concentration from his fasting plasma were 4.8, 11.9 and 0.4 mmol/l, respectively. The lipoprotein lipase (LPL) activity and mass in the postheparin plasma (PHP) from the patient were 0.58 mmol/ml/h (normal range: 7.7+/-2.6) and 244 ng/ml (normal range: 192+/-30), respectively. The hepatic lipase activity of the PHP from the patient was 10.6 mmol/ml/h (normal range: 9.9+/-3.6). DNA analysis of the LPL gene revealed that this patient had a heterozygous one nucleotide deletion of A coding Asn 291, resulting in a premature termination of the LPL protein at amino acid residue 303. The other abnormality in the LPL gene of the proband was an amino acid residue 194 defect (Ile194-->Thr), which is known to cause a defective enzyme. A medium-chain triglyceride (MCT) loading test was conducted to find how this triglyceride affects plasma lipoprotein metabolism in this patient in a short term (Fig. 3). The plasma total cholesterol (TC) or high density lipoprotein (HDL)-C levels did not change significantly after oral administration of a fatty meal containing long chain triglycerides (LCT) or MCT. The plasma TG level, on the other hand, increased from 11.9 to 19.2 mmol/l (+61%) at 6 h after loading a fatty meal containing LCT, whereas the plasma TG levels tended to even decrease at 6 h after oral administration of an MCT, tricaprin (from 11.6 to 10.5 mmol/l (-9.4%)). These results suggest that MCT, as opposed to LCT, is useful for treatment of type I hyperlipidemia with a novel mutation at the notable amino acid Asn 291 of the LPL gene.

Adult↗

PubMed1999

Extremely high and specific activity of DNA enzymes in cells with a Philadelphia chromosome.

BACKGROUND: Chronic myelogenous leukemia (CML) results from chromosome 22 translocations (the Philadelphia chromosome) that creates BCR-ABL fusion genes, which encode two abnormal mRNAs (b3a2 and b2a2). Various attempts to design antisense oligonucleotides that specifically cleave abnormal L6 BCR-ABL fusion mRNA have not been successful. Because b2a2 mRNA cannot be effectively cleaved by hammerhead ribozymes near the BCR-ABL junction, it has proved very difficult to engineer specific cleavage of this chimeric mRNA. Nonspecific effects associated with using antisense molecules make the use of such antisense molecules questionable. RESULTS: The usefulness of DNA enzymes in specifically suppressing expression of L6 BCR-ABL mRNA in mammalian cells is demonstrated. Although the efficacy of DNA enzymes with natural linkages decreased 12 hours after transfection, partially modified DNA enzymes, with either phosphorothioate or 2'-O-methyl groups at both their 5' and 3' ends, remained active for much longer times in mammalian cells. Moreover, the DNA enzyme with only 2'-O-methyl modifications was also highly specific for abnormal mRNA. CONCLUSIONS: DNA enzymes with 2'-O-methyl modifications are potentially useful as gene-inactivating agents in the treatment of diseases such as CML. In contrast to conventional antisense DNAs, some of the DNA enzymes used in this study were highly specific and cleaved only abnormal BCR-ABL mRNA.

Cells, Cultured↗

PubMed1999

Delayed post-prandial lipid metabolism in subjects with intra-abdominal visceral fat accumulation.

BACKGROUND: Individuals with obesity, in particular those with intra-abdominal visceral fat accumulation, are known to have various complications, such as hyperlipidaemia, impaired glucose tolerance, hyperinsulinaemia and hypertension, leading to the development of coronary heart disease. Post-prandial hyperlipidaemia has repeatedly been shown to be an independent risk factor for coronary heart disease. The aim of the present study was to investigate post-prandial lipoprotein metabolism in subjects with excessive visceral fat accumulation. MATERIALS AND METHODS: Eighty-three patients (52 men, 31 women) [average age 48 +/- 14 years; mean body mass index (BMI) 25 +/- 5 kg m-2] were recruited to the study. Visceral (or subcutaneous) fat accumulation was analysed as areas of fat deposition by computerized tomography at the umbilicus level. After a 12-h overnight fast, oral vitamin A and a fatty meal (40 g m-2 fresh cream containing 50 000 units m-2 vitamin A) were administered to these subjects. The concentration of retinyl palmitate (RP) was measured by high-performance liquid chromatography. RESULTS: The visceral fat area (V) was positively correlated with plasma triglyceride (TG) 0, 2, 4 and 6 h after fat loading and with plasma RP 0, 4 and 6 h after fat loading. The BMI did not show any correlation with plasma TG and RP at any point. The visceral fat area was positively correlated with the RP area under the curve (AUC) in the serum from the subjects [V vs. RP AUC: n = 83, r = 0.327, P = 0.013]. The BMI of the subjects did not show any correlation with the RP AUC (r = 0.021, P = 0.85). CONCLUSION: These results suggest that post-prandial lipid metabolism is impaired in subjects with intra-abdominal visceral fat accumulation, irrespective of BMI, leading to the development and progression of coronary atherosclerosis.

Abdomen↗

PubMed1999

Ubiquitination of the transcriptional coactivator p300 during retinic acid induced differentiation.

Transcriptional coactivator p300 plays an important role in differentiation processes of various cell lines. In this report, we examined levels of p300 protein and the related protein, CREB binding protein (CBP), during the retinoic acid (RA)-induced differentiation of F9 cell. As a result, the level of p300 protein began to decrease at 36 h after treatment with RA dramatically, however, the level of CBP protein did not alter. Moreover, ubiquitinated p300 protein was only detected in differentiated F9 cells. These results suggest that p300 protein is possibly degraded via the ubiquitin-dependent pathway during the RA-induced differentiation of F9 cells.

Animals↗

PubMed1999

Probing of the secondary structure of maxizymes.

The protein encoded by chimeric BCR-ABL mRNA causes chronic myelogenous leukemia (CML). We showed previously that a novel allosterically controllable ribozyme, of the type known as a maxizyme, can cleave this mRNA, with high specificity and high-level activity in vivo. In order to probe the putative conformational changes, we used a weakly alkaline solution to hydrolyze differentially phosphodiester bonds that were located in different environments. As indicated by earlier data obtained in vivo, our results demonstrated that the active conformation was achieved only in the presence of the junction within the chimeric BCR-ABL mRNA.

Allosteric Regulation↗