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Biomedical subjects

T Tamura

Publications and source records attributed to T Tamura.

At least 289 records · Page 16Linked to original sources
PubMed1999

Analysis of strain variation of R1 repeated structure in varicella-zoster virus DNA by polymerase chain reaction.

The tandem direct reiteration R1 in the varicella-zoster virus genome consists of two elements: units composed of 18 bp and those having 15 bp, both of whose numbers and types of combination patterns vary among strains. The variations of the R1 structure were examined in order to differentiate between the wild strains and a varicella vaccine (Oka) strain by the polymerase chain reaction using two primer sets. The results showed that the 31 wild strains were classified into nine patterns: the R1 structure consisted of a combination of 5 to 7 18-bp units and 8 to 12 15-bp units. The strain with a combination of 6 18-bp units and 10 15-bp units was found to be predominant in Japan, and the same pattern was found in the vaccine strain, so that differentiation between the vaccine strain and the wild strains in Japan merely by analysis of R1 in VZV genome is difficult.

DNA, Viral↗
PubMed1999

Mid-term follow-up of coronary artery aneurysm after directional coronary atherectomy.

Coronary artery aneurysm (CAA) occurs in 6-12% of lesions after directional coronary atherectomy (DCA). The prognosis and the optimal treatment for DCA-related CAAs have not been well known. Therefore, we reviewed the clinical course of 214 consecutive patients with DCA-related CAAs who underwent DCA in our hospital. Follow-up coronary angiography 6 months after DCA was completed in 193 patients (212 lesions) and 14 lesions with CAAs (14 patients) were detected. We evaluated these 14 lesions by repeat coronary angiography at an average of 32 months after DCA in comparison with the adjacent reference vessel. Twelve of the 14 patients have been uneventful but 2 suffered from de novo angina due to new stenotic lesion unrelated to the DCA procedures. We compared the preprocedural angiographic characteristics and periprocedural parameters between the 14 lesions with CAAs[CAA(+)group] and the 198 without CAAs [CAA(-)group], but found no significant differences. Histological examination of specimens retrieved during atherectomy demonstrated that subintimal resection was more frequent in the CAA(+)group(57%) than the CAA(-)group(31%). The diameter of the aneurysm divided by the reference diameter was significantly larger at 6 months immediately after DCA(1.71 +/- 0.21 vs 1.31 +/- 0.18, p < 0.05) but did not change subsequently (1.68 +/- 0.23). Our retrospective analysis revealed a good mid-term (an average of 32 months) prognosis for CAAs found by routine follow-up coronary angiography and also demonstrated that the depth of resection was significantly associated with aneurysm formation.

Adult↗
PubMed1999

[Optimal dosage of contrast material in brain enhanced CT].

PURPOSE: To assess the optimal contrast dosage for brain enhanced CT. MATERIALS AND METHODS: A total of 150 patients were randomly assigned to two groups. The patients were also divided by body weight into three groups (< 50 kg, 50-59.9 kg and > or = 60 kg). A total of 100 ml (in 77 patients) or 50 ml (in 73 patients) of contrast material (iopamidol 300 mgI/ml) was intravenously administrated at a speed of 1 ml/sec. Three diagnostic radiologists evaluated image quality by five- or two-stage scoring systems with special attention given to enhancement of the anterior and middle cerebral arteries. CT values of the basilar artery were also measured. RESULTS: In visual evaluation by the five-stage scoring system, image quality with 100 ml of contrast material was better than that with 50 ml in all body-weight groups, although no difference was observed with the two-stage scoring system in patients weighing less than 60 kg. CT values of the basilar artery were higher in patients given 100 ml than in those given 50 ml regardless of weight groups. CONCLUSION: The image quality of brain CT using 50 ml of contrast material is sufficient for correct diagnosis in patients with a body weight of less than 60 kg.

Adolescent↗
PubMed1999

Survival and prognostic factors in lung cancer patients treated in phase I trials: Japanese experience.

Patients recruited for phase I trials are considered to have a poor prognosis, because the majority of them have already been heavily treated. We examined the survival of lung cancer patients admitted to phase I trials and treated with single new investigational chemotherapeutic agents or new investigational biological modifiers in the Division of Thoracic Oncology of the National Cancer Center Hospital between 1987 and 1993. Eighty-two patients had lung cancer among 121 patients registered in phase I trials. To identify prognostic factors, univariate and multivariate analyses were conducted. Median survival time (MST) from beginning of the phase I trial was 9.4 months, and the response rate was 4.2%. There were 11 (13.4%) early deaths within 3 months, and the death of 1 (1.2%) patient was treatment-related. Univariate analysis demonstrated that performance status, body weight loss, chemotherapy regimen, liver metastasis, number of metastatic sites, prior chemotherapy, and serum levels of hemoglobin, and lactate dehydrogenase were significant prognostic factors for survival. Among these factors, performance status >1, body weight loss >/=10%, and number of the metastatic sites >1 were selected as risk factors in multivariate regression analysis. The low-risk group, which included the 36 patients with no risk factors, had an MST of 13.9 months and an early death rate of 0%. The intermediate-risk group of 31 patients was characterized by patient having only one risk factor. These patients had an MST of 7.6 months and an early death rate of 13%. The high-risk group of 9 patients had two or three risk factors. These patients had an MST of only 1.5 months and a high early death rate of 78%. We conclude that the MST of lung cancer patients who participated in the phase I trials was 9.4 months. Therefore, it appears reasonable to have admitted these patients to the phase I trials. However, as the patients in the high-risk group had a poor outcome and high early death rate, they should not have been admitted to phase I trials. This prognostic model should be validated in other patient series.

Adenocarcinoma↗
PubMed1999

[A 13-week subchronic toxicity study of chitin in F344 rats].

A subchronic toxicity study of chitin, a natural structural component of crustacean shells, was performed in F344 rats by feeding of the powdered diet containing 5%, 1.7%, 0.6%, 0.2%, and 0% concentrations of the substance. Each group consisted of 10 males and 10 females. All animals survived until the end of the experiment. There were no changes indicating obvious toxicity of chitin in the clinical signs, body weight, food intake, hematology, serum biochemistry, or histopathological findings, except a slight decrease in body weight gain in the 5% chitin-treated males. Although the mechanism is unclear, the suppression of body weight gain may be due to the slight decrease in caloric content of the food in the 5% chitin-treated animals, a change unrelated to toxicity. Thus, there was no obvious toxicity of chitin in F344 rats at concentrations up to 5% in the diet for 13 weeks.

Administration, Oral↗
PubMed1998

The role of tricorn protease and its aminopeptidase-interacting factors in cellular protein degradation.

Tricorn protease was previously described as the core enzyme of a modular proteolytic system displaying multicatalytic activity. Here we elucidate the mode of cooperation between Tricorn and its interacting factors, and we identify two additional factors, F2 and F3, closely related aminopeptidases of 89 kDa. In conjunction with these three factors, Tricorn degrades oligopeptides in a sequential manner, yielding free amino acids. We have been able to reconstitute a proteolytic pathway comprising the proteasome, Tricorn, and its interacting factors, F1, F2, and F3, which converts proteins efficiently into amino acids. Therefore, it is quite likely that Tricorn also acts in vivo downstream of the proteasome and, in cooperation with its interacting factors, completes protein catabolic pathways.

Amino Acid Sequence↗
PubMed1998

Cloning of a novel rat gene, DB83, that encodes a putative membrane protein.

Using a partial cDNA sequence and a 5'-RACE technique, we isolated a novel cDNA from rat liver referred to as DB83. DB83 had four hydrophobic trans-membrane domains and one N-myristoylation site as well as multiple possible phosphorylation sites. The db83 gene was highly expressed in the liver and significantly in brain, lungs and kidneys. We suggest that DB83 is a tissue-specific putative membrane protein. p6

Amino Acid Sequence↗
PubMed1998

Influence of Surfactant Structure on the Drainage of Nonionic Surfactant Foam Films.

The stability of vertical liquid films produced from aqueous solutions of polyoxyethylene alkyl ether (CnEm) was studied by monitoring the dynamic surface tension (gammat) and aqueous core thickness of a vertical foam film (d2) measured by FT-IR. The temperature dependence of the drainage patterns of the liquid films was clarified for CnE8 (n = 10, 12, 14, and 16) solutions. It was found that the critical thickness (Drup) where the film rupture happens increased with increasing temperature in the case of C10E8 and C12E8, while Drup remarkably decreased and finally formed a black film in the case of C14E8 and C16E8 solutions within the measured temperature range. In addition, a delay in the film drainage occurred in these systems, which was caused by the stabilization of the films via the Marangoni effect proved by dynamic surface tension measurements. On the other hand, heterogeneous ethoxylated dodecyl ethers (C12Em) modified with a hydrophilic group showed a remarkable increment of Drup under dynamic conditions without the Marangoni stabilization in the foam film. Adding a hydrophobic group at the end of the polar head produces a large area per molecule and causes a large increase in the surface coverage of the air bubbles. However, a less structured surface coverage facilitated the breaking of the foam during the Ross and Miles test. These results indicate that under dynamic conditions, the Marangoni effect and the hydrophobic interaction at the surface become important for foam film rupture. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

Unpredicted clinical pharmacology of UCN-01 caused by specific binding to human alpha1-acid glycoprotein.

The pharmacokinetics of UCN-01 after administration as a 72- or 3-h infusion to cancer patients in initial Phase I trials displayed distinctive features that could not have been predicted from preclinical data. The distribution volumes (0.0796-0.158 liters/kg) and the systemic clearance (0.0407-0.252 ml/h/kg) were extremely low, in contrast to large distribution volume and rapid systemic clearance in experimental animals. The elimination half-lives (253-1660 h) were unusually long. In vitro protein binding experiments demonstrated that UCN-01 was strongly bound to human alpha1-acid glycoprotein. The results suggest that unusual pharmacokinetics of UCN-01 in humans could be due, at least in part, to its specifically high binding to alpha1-acid glycoprotein.

Alkaloids↗
PubMed1998

Helicobacter pylori generates superoxide radicals and modulates nitric oxide metabolism.

During studies of the bactericidal action of nitric oxide (NO), we found that it reversibly inhibited the respiration of Escherichia coli and irreversibly inhibited the respiration of Helicobacter pylori. Peroxynitrite, a reaction product of NO and superoxide, irreversibly inhibited the respiration of both H. pylori and E. coli. H. pylori, but not E. coli, generated substantial amounts of superoxide radicals. These results suggest that NO directly inhibits the respiration of E. coli whereas it rapidly reacts with endogenously generated superoxide radicals in H. pylori. The resulting peroxynitrite inactivates the respiration of H. pylori.

Escherichia coli↗
PubMed1998

Mitogenic activity of endothelin on human cultured prostatic smooth muscle cells.

The effects of endothelins on human prostatic smooth-muscle cell growth were examined. Endothelin-1 and endothelin-3 induced a concentration-dependent increase in DNA synthesis and also promoted cell growth. Use of subtype selective antagonists BQ-123 ((cyclo(D-Trp-D-Asp(ONa)-Pro-D-Val-Leu); endothelin ET(A) receptor selective) and BQ-788 ((N-cis-2,6-dimethylpiperidinocarbonyl-L-gamma-methyl Leu-D-Trp-(COOMe)-D-Nle-ONa); endothelin ET(B) receptor selective), indicated that mitogenic effects of endothelin were mediated through activation of both endothelin ET(A) and ET(B) receptors. The mitogenic effects of endothelin-1 and endothelin-3 were significantly inhibited by pretreatment of the cells with pertussis toxin. However, mitogenesis due to basic fibroblast growth factor was not affected. In conclusion, endothelin has mitogenic effects on human prostatic smooth muscle cells through activation of both endothelin ET(A) and ET(B) receptors via different signalling pathways from basic fibroblast growth factor. This may contribute to smooth muscle hyperplasia associated with benign prostatic hyperplasia.

Aged↗
PubMed1998

TIP49, homologous to the bacterial DNA helicase RuvB, acts as an autoantigen in human.

TATA-binding protein (TBP), a central component for transcriptional regulation, forms complexes with various transcription regulators. We have isolated a novel human cDNA for a 49-kD TBP-interacting protein (TIP49). The human TIP49 was highly homologous to bacterial RuvB proteins that function as a DNA helicase to promote branch migration of the Holliday junction. Immunofluorescence analysis using anti-TIP49 antibody showed a typical dot-shaped nuclear staining pattern, suggesting that TIP49 is included in a macromolecular structure in the nucleus and may participate in nuclear events such as transcription and recombination. Moreover, glycerol gradient analysis demonstrated that TIP49 is present in a macromolecular complex in nuclear extracts. Interestingly, we detected a high level of autoantibodies against TIP49 in sera of patients with autoimmune diseases such as polymyositis/dermatomyositis and autoimmune hepatitis. This indicates that the autoantibody against this protein is a new marker for particular connective tissue diseases. These findings provide further evidence that the macromolecular structures described above are targeted by an autoimmune mechanism. The anti-TIP49 antibodies can be useful probes for clinical diagnosis and for investigation of intranuclear structure.

ATPases Associated with Diverse Cellular Activitie↗
PubMed1998

The TIMP2 membrane type 1 metalloproteinase "receptor" regulates the concentration and efficient activation of progelatinase A. A kinetic study.

We have used C-terminal domain mutants to further define the role of interactions of progelatinase A and membrane type 1 matrix metalloproteinase (MT1 MMP) in the binding of TIMP2 and in the cell-associated activation of progelatinase A. Soluble constructs of MT1 MMP were used to demonstrate that binding with TIMP2 occurs primarily through N-terminal domain interactions, leaving the C-terminal domain free for interactions with progelatinase A. The rate of autolytic activation of progelatinase A initiated by MT1 MMP cleavage could be potentiated by concentration of the proenzyme by binding to heparin. Residues 568-631 of the progelatinase A C-terminal domain are important in formation of the heparin binding site, since replacement of this region with the corresponding stromelysin-1 sequence abolished binding to heparin and the potentiation of activation. The same region of gelatinase A was required for binding of latent and active enzyme to TIMP2, but residues 418-474 were not important. A similar pattern was seen using cell membrane-associated MT1 MMP; residues 568-631 were required for binding and activation of progelatinase A, whereas residues 418-474 were not. Neither region was required for activation in solution. The addition of TIMP2 to HT1080 membrane preparations expressing MT1 MMP, but depleted of endogenous TIMP2, resulted in potentiation of progelatinase A activation. This effect was dependent upon TIMP2 binding to MT1 MMP rather than at an independent membrane site. Together, the data suggest that TIMP2 forms a receptor with MT1 MMP that regulates the concentration and efficient generation of functionally active gelatinase A.

Animals↗
PubMed1998

Stenting after thrombectomy with the AngioJet catheter for acute myocardial infarction.

The presence of massive intracoronary thrombi may contraindicate stenting. The AngioJet catheter rheolytic thrombectomy prepared the road for an easy and uneventful stenting in 2 patients with acute myocardial infarction (AMI) and thrombi. This combination provides a promising strategy for patients with AMI and angiographic evidence of massive thrombi.

Aged↗
PubMed1998

Novel guide catheter for left coronary intervention via a right upper limb approach.

We designed a novel guide catheter specifically for interventions to the left coronary artery via a right upper limb approach. The catheter has a novel first loop design which utilizes the angle between the right subclavian and innominate arteries for support. The first loop introduces the catheter into the correct position and generates powerful and coaxial back-up power. We report successful implantation of Palmaz-Schatz stents in five cases using this 6 Fr. catheter.

Aged↗
PubMed1998

Effects of cilostazol on late lumen loss after Palmaz-Schatz stent implantation.

Cilostazol inhibits intimal hyperplasia after stent implantation into canine iliac arteries. To determine the antiproliferative effect of this agent, cilostazol or aspirin was randomly given for 6 mo to 36 patients treated with Palmaz-Schatz stent implantation. Initial success was obtained in 34 patients. Repeat angiography was performed in 33 patients, and the complete angiographic data were obtained in 22 lesions of the cilostazol group and in 21 lesions of the aspirin group. The reference diameter and minimal luminal diameter were similar in both groups before and immediately after stent implantation. At follow-up, minimal luminal diameters were significantly greater in the cilostazol group than in the aspirin group (P < 0.001). Late loss and loss index were significantly smaller in the cilostazol group than in the aspirin group (P < 0.001). These results suggest that cilostazol reduces angiographic late lumen loss and thereby may reduce the incidence of restenosis after Palmaz-Schatz stent implantation.

Aged↗
PubMed1998

Initial and follow-up results of the ACS multi-link stent: a single center experience.

The Palmaz-Schatz (PS) stent has effectively reduced restenosis; however its rigidity makes it sometimes difficult or impossible to deliver. The initial and follow-up outcomes with the ACS Multi-Link stent (deployed from April to November 1995) were evaluated in 70 patients (79 lesions): unplanned in 34% (abrupt closure 1%; threatened closure 5%; suboptimal results 28%) and planned in 66%. Three to six month follow-up angiograms were analyzable in 67 lesions; 96% procedural (in nine lesions PS stenting had failed) and 95% clinical success were achieved. In-hospital mortality was 1.4%. Myocardial infarction occurred in 2.9%, and subacute stent thrombosis in 1.4%. Stenting improved immediately the minimal luminal diameter (from 0.97+/-0.41 mm to 2.72+/-0.31 mm), but at 6 months it had decreased to 1.89+/-0.44 mm. Angiographic restenosis (<50% diameter stenosis) occurred in 11, a rate of 16.4%; target lesion revascularization (TLR) was required in six (re-PTCA in five or bypass surgery in one; 6/67=8.7%). Actuarial 1-2 year survival rate was 91%, 80% surviving free from major complications or need for TLR. We conclude that the ACS Multi-Link stent can be implanted in lesions unsuited for the PS stent with a high success rate, and an anticipated restenosis rate perhaps comparable to with the PS stent.

Aged↗