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Biomedical subjects

A Tabuchi

Publications and source records attributed to A Tabuchi.

At least 73 records · Page 4Linked to original sources
PubMed1994

[A case of hypertrophic obstructive cardiomyopathy (HOCM) complicated by infective endocarditis (IE) and mitral regurgitation (MR)].

The case of a 56-year-old man who underwent mitral valve replacement due to HOCM complicated by IE and MR is reported. Preoperative 2D echocardiographic assessment of the mitral valve revealed systole anterior motion (SAM) and vegetation, and color flow Doppler echocardiographic examination revealed severe mitral regurgitation. The left ventricular out-flow tract gradient decreased from 140 mmHg preoperatively to 60 mmHg postoperatively. Mitral valve replacement should be considered in patients with associated IE and severe MR.

Cardiomyopathy, Hypertrophic↗
PubMed1993

Cloning of Chinese hamster DNA topoisomerase I cDNA and identification of a single point mutation responsible for camptothecin resistance.

A camptothecin-resistant (DC3F/C-10) Chinese hamster cell line that contains a catalytically altered and camptothecin (CPT)-resistant DNA topoisomerase I (top 1) (Tanizawa, A., and Pommier, Y. (1992) Cancer Res. 52, 1848-1854) and the parent cell line (DC3F) were used to compare top 1 mRNAs and cDNAs. Northern blot analysis showed a single 4.1-kilobase band without quantitative reduction between the two cell lines. We have cloned and sequenced top 1 cDNAs. DC3F and DC3F/C-10 top 1 c-DNA are 3591 and 3626 base pair long, respectively, and encode 767 amino acids. The homology of deduced amino acid sequences between Chinese hamster and mouse or human top 1 are 98.1 and 96.7, respectively. cDNAs from DC3F/C-10 and DC3F cells differ by a single base point mutation (G to A) which results in an amino acid change from Gly505 to Ser (Gly505-->Ser). G505 corresponds to Gly503 of human top 1 cDNA and is located 220 amino acids away from the presumed catalytic Tyr725. The point mutation in the Chinese hamster top 1 is located in a region that is highly conserved among all cloned top 1 cDNAs (plant ATH, vaccinia virus, Shope fibroma virus, Drosophila, Saccharomyces cerevisiae, Schizosaccharomyces pombe, mouse, and Human). A mutation of Asp533 to Gly in this same region has been shown to confer CPT resistance for human top 1. Chinese hamster top 1 protein with a Gly505-->Ser mutation that was expressed in bacteria was resistant to CPT, indicating that this single base mutation is involved in CPT resistance. Our results suggest that the highly conserved region around Gly505 plays an important role in the interactions among top 1, DNA, and CPT.

Amino Acid Sequence↗
PubMed1993

[An adult case of anomalous origin of left coronary artery from pulmonary trunk: left coronary artery blood flow after closing of origin of left coronary artery].

An adult case of anomalous origin of left coronary artery from pulmonary trunk was reported. The catheterization studies revealed significant amount of left to right shunt in the pulmonary trunk and anomalous origin of left coronary artery from pulmonary artery with well developed and marked tortuously dilated collaterals from the right coronary artery. During surgery, blood flow waveforms of the LAD was measured using pulsed Doppler velocimeter. After temporary closing of the origin of left coronary artery, blood flow of the LAD markedly decreased. A-C bypass grafting to LAD was performed successfully using saphenous vein and graft flow rate was 220 ml/min. These findings suggest that the coronary blood flow through the tortuously dilated collaterals after ligation of the origin of left coronary artery was insufficient to perfuse the left coronary artery.

Adult↗
PubMed1993

[Coronary reoperation--report of 16 cases].

Between January 1975 and July 1992, coronary artery reoperation was performed in 16 of 333 patients who had undergone primary bypass grafting. The interval between the operations ranged from 2 to 147 months. Reoperation was done within one year in two patients, within one to five years in five patients and after more than five years in nine patients. The mean number of bypass grafts was 2.31 per patient in the first operation and 1.75 in the reoperation. The main reasons for the reoperation were an occlusion of the graft in 12 cases and both graft occlusion and new coronary artery disease in 3 cases. In one other case, an emergency right coronary bypass graft done for an acute occlusion during PTCA to an area of right coronary artery stenosis 13 months after two bypass graftings to the LAD and circumflex coronary artery. Fourteen cases had vein graft disease bypassed to the LAD or new coronary artery disease in the LAD and required reoperations of the LAD. In the case with a recurrence of myocardial ischemia after coronary bypass surgery and with bypass grafts to the LAD that were patent, there were no cases requiring reoperation. These findings demonstrate that patency of the grafts to the LAD is an important factor for reoperation after myocardial revascularization surgery.

Age Factors↗
PubMed1992

Function of the N-terminal half of RepA in activation of Rts1 ori.

The RepA protein of the Rts1 plasmid, consisting of 288 amino acids, is a trans-acting protein essential for replication. A mutant repA gene, repA delta C143, carrying a deletion that removed the 143 C-terminal amino acids of RepA, could transform, but at a low frequency, an Escherichia coli polA strain, JG112, when repA delta C143 was cloned into pBR322 with Rts1 ori in the natural configuration. The transformation was less efficient without the dyad DnaA box in the ori region, and no transformation occurred at 42 degrees C, characteristic of Rts1 replication. A fusion of the 3'-terminal half of repA of the P1 plasmid to repA delta C143 yielded a pBR322 chimeric plasmid that contained Rts1 ori through hybrid (Rts1-P1) repA. This plasmid was maintained much more stably in JG112 at 37 degrees C. At 42 degrees C, however, it was quite unstable. The overproduced hybrid RepA protein showed interference with mini-Rts1 replication in trans and also exhibited an autorepressor function, although both activities were decreased. These findings suggest that the N-terminal half of the RepA molecule of Rts1 is involved in the activation of the replication origin.

Bacterial Proteins↗
PubMed1992

Autoregulation of the stability operon of IncFII plasmid NR1.

The stb locus of IncFII plasmid NR1, which mediates stable inheritance of the plasmid, is composed of an essential cis-acting DNA site located upstream from two tandem genes that encode essential stability proteins. The two tandem genes, stbA and stbB, are transcribed as an operon from promoter PAB. Using PAB-lacZ gene fusions, it was found that the stb operon is autoregulated. A low-copy-number stb+ plasmid introduced into the same cell with the PAB-lacZ fusion plasmid repressed beta-galactosidase activity about 5-fold, whereas a high-copy-number stb+ plasmid repressed beta-galactosidase about 15-fold. The details of autoregulation were analyzed by varying the concentrations of StbA and StbB to examine their effects on expression from the PAB-lacZ fusion plasmid. StbB protein by itself had autorepressor activity. Although StbA protein by itself had no detectable repressor activity, plasmids that encoded both stbA and stbB repressed more effectively than did those that encoded stbB alone. Plasmids with a mutation in stbA had reduced repressor activity. One mutation in stbB that inactivated the stability function also reduced, but did not eliminate, repressor activity. Repressor activity of the mutant StbB protein was effectively enhanced by stbA. These results indicate that StbB serves two functions, one for stable inheritance and one for autoregulation of the stb operon, both of which may be influenced by StbA protein.

DNA Transposable Elements↗
PubMed1992

[Choice of conduit in coronary bypass surgery].

Since 1987, arterial conduits have been used in 78 of 130 cases receiving coronary bypass surgery, including 25 treated by arterial conduits alone. The use of arterial conduits was mainly indicated to the anterior descending coronary artery (LAD), but the saphenous vein had to be used in 39 percent, 47 of 120 cases receiving bypass grafting to the LAD for various reasons including a combination of multiple obstructive arteriosclerosis, multiple bypass graftings in the aged, unstable angina, emergency operation and no suitable artery for a conduit as indicated by preoperative angiography. Hereafter, arterial conduits for coronary bypass grafting to LAD should be used in many more cases to the best possible advantage.

Adult↗
PubMed1992

[Coronary bypass surgery using arterial conduit and its pitfall].

Three patients with spasm of internal mammary arteries and gastroepiploic artery immediately after coronary bypass surgery were reported. On completion of the revascularization, all patients could not be weaned from cardiopulmonary bypass. The flow velocity waveforms of the arterial grafts measured by pulsed Doppler velocimeter showed only small systolic component without diastolic flow and the palpation revealed profound spasm partially in the arterial conduits. Although all patients could be weaned from cardiopulmonary bypass only after insertion of a saphenous vein graft, two of them died on the next day. In all patients, free flow measured prior bypass was considered to be sufficient and a technically satisfactory anastomosis was felt to be performed. If a profound hemodynamic instability as a result of intractable spasm of arterial conduit occurred after completion of coronary bypass surgery, an additional saphenous vein graft should be placed before discontinuation of cardiopulmonary bypass.

Aged↗
PubMed1992

[The influence of increase in heart rate on coronary flow dynamics in the patients with aortic stenosis].

To clarify the causative factors responsible for the development of effort angina in aortic stenosis, the influence of an increase in heart rate by atrial pacing and isoproterenol infusion on the phasic left coronary flow velocity waveforms were studied using a pulsed Doppler velocimeter during cardiac surgery. Coronary flow velocity waveforms in aortic stenosis was characterized by a slowly increased diastolic inflow and an elongation of the time from the onset of diastole to the diastolic peak velocity. An increase in heart rate by pacing brought about a marked decrease in diastolic coronary flow since the slowly increasing diastolic flow was cut with the onset of following systole. On the contrary, after an increase in heart rate by infusion of isoproterenol, diastolic increasing rate in the coronary flow waveform accelerated and diastolic peak velocity markedly increased. As the results, isoproterenol produced a significant increase in diastolic coronary inflow.

Aged↗
PubMed1991

Transcription of the stability operon of IncFII plasmid NR1.

The stability (stb) locus of IncFII plasmid NR1 is composed of an essential cis-acting DNA site located upstream from two tandem genes that encode essential stability proteins. The stb locus was found to be transcribed from a promoter site just upstream from the first gene, stbA. This promoter was active for transcription both in vivo and in vitro and was located within the region that includes the essential cis-acting site. Transcripts initiated from this site were approximately 1,500 to 1,600 nucleotides in length. Northern (RNA) blot analysis indicated that the transcripts traversed both stbA and the downstream gene, stbB. Mutants from which the promoter had been deleted failed to produce detectable transcripts from either stbA or stbB. Transcription of a third open reading frame, stbC, which is contained within the stbB gene in the opposite DNA strand, could not be detected. For a mutant in which a transposon had been inserted in stbA, no transcription of stbB was detected. After deletion of most of the transposon, which left behind a 35-bp frameshift insertion in stbA, transcription of stbB was restored, although the insertion still had a polar effect on stbB function. The rate of in vivo transcription of the stb locus was measured by pulse-labeling of RNA followed by quantitative RNA-DNA hybridization. Mutants deleted of stbB had an approximately 10-fold increase in the rate of transcription, whereas those deleted of the promoter region had at least a 10-fold reduction in transcription rate. The half-life of stb mRNA was approximately 2 min. These data suggest that stbA and stbB are cotranscribed as an operon that may be autoregulated.

Blotting, Northern↗
PubMed1990

[Hilar and mediastinal lymph node metastases from lung cancer; detection with CT and MR imaging].

Sixty-one patients with primary lung cancer, who had CT and MR imaging before surgery, were studied. MR imaging used spin-echo sequences with T1 weighted image and T2 weighted image (C-MRI), and included STIR technique (Stir-MRI). The accuracy of diagnosis of mediastinal lymphadenopathy (regarding 10 mm or larger in short transverse diameter as positive) was 89% by CT, 84% by C-MRI and 89% by Stir-MRI. The accuracy of diagnosis of hilar lymphadenopathy was 42% by CT, 67% by C-MRI, and 75% by Stir-MRI. The accuracy of diagnosis of mediastinal lymph node metastases was 89% by CT, 94% by C-MRI and 96% by Stir-MRI. The accuracy of diagnosis of hilar lymph node metastases was 78% by CT, 87% by C-MRI and 89% by Stir-MRI. The possibility of enhancement of diagnostic accuracy of lymph node metastases from lung cancer was suggested by combining MR imaging included STIR technique with CT.

Adenocarcinoma↗
PubMed1988

Complementation of mutants of the stability locus of IncFII plasmid NR1. Essential functions of the trans-acting stbA and stbB gene products.

A series of unstable mutants of the stability (stb) locus of IncFII plasmid NR1 was subjected to a complementation analysis. The mutant collection included plasmids with point, insertion and deletion mutations in stb. These mutations affected the tandem genes stbA and stbB, which encode stability proteins StbA and StbB, or the PAB transcription promoter, which is located upstream from stbA in a region that contains an essential cis-acting site. Deletion mutants that lacked the region containing promoter PAB could not be complemented (stabilized) by providing StbA and StbB in trans. Deletion mutants that lacked stbA and stbB but retained the PAB region were complemented in trans but required both StbA and StbB, indicating that both proteins were essential for stable inheritance. stbA- point mutants were complemented in trans by either wild-type or stbA+ stbB- clones of the stability region. However, mutants with insertions in stbA were complemented only by wild-type clones, which suggested the insertions were polar on expression of the downstream stbB gene. A plasmid with a stbB- point mutation was complemented in trans by wild-type but not by stbA- stbB+ clones. In addition, plasmid clones that expressed StbB in the absence of StbA caused destabilization of (were incompatible with) stb+ derivatives of NR1 in trans, whereas clones that expressed only wild-type StbA or both StbA plus StbB did not. Plasmid clones that contained only the essential cis-acting PAB region did not cause destabilization of stb+ plasmids in trans. These results suggest that an excess of StbB protein provided in trans may cause a depletion of the essential StbA protein. Therefore, these results may be consistent with the hypothesis that StbB is an autorepressor of the stbAB operon.

Bacterial Proteins↗
PubMed1988

Genetic organization and nucleotide sequence of the stability locus of IncFII plasmid NR1.

The stability (stb) locus of IncFII plasmid NR1 was mapped to a 1700 base-pair NaeI-TaqI restriction fragment. A series of unstable plasmids that contained insertion, deletion, and point mutations that inactivated the stability function was isolated. The unstable point mutants examined were all stabilized (complemented) in trans by a copy of the wild-type stb locus, suggesting that the mutations had inactivated diffusible gene products. The nucleotide sequence of the stb locus contained two tandem open reading frames, designated stbA and stbB, that encoded essential trans-acting protein products with predicted sizes of 36,000 Mr and 13,000 Mr, respectively. A third open reading frame, stbC, that could encode a peptide of 8000 Mr was contained within stbB in the complementary DNA strand. Plasmid-encoded proteins of 36,000 Mr and 13,000 Mr were identified in minicell experiments as the products of stbA and stbB, respectively. Unstable deletion mutants that retained the promoter proximal region of the stb locus upstream from stbA but had deleted both stbA and stbB were stabilized in trans by plasmids that could supply StbA and StbB. In contrast, deletion mutants that had lost the stbAB promoter region were not complemented in trans, indicating that this region contained an essential cis-acting site (or sites). Unlike some other loci that mediate stable plasmid inheritance, cloned copies of the wild-type stb locus of NR1 did not exert strong incompatibility (i.e. trans destabilization) against other stb+ derivatives of plasmid NR1 present in the same cell.

Bacterial Proteins↗
PubMed1988

Visualization of ocular melanoma with N-isopropyl-p-[123I]-iodoamphetamine.

In a patient with ocular melanoma, scintigraphy with N-isopropyl-p-[123I]-iodoamphetamine [( 123I]IMP) clearly delineated the histologically proven ocular lesion. In a tissue distribution study, using the resected specimen, a significantly high accumulation of the radioactivity was confirmed in tumor tissue. Thus, [123I]IMP scintigraphy provided specific localization of an ocular melanoma.

Amphetamines↗