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T Akasaka

Publications and source records attributed to T Akasaka.

At least 181 records · Page 10Linked to original sources
PubMed1994

Clinical aspects of B-cell malignancy involving the BCL1/PRAD1 locus.

BCL1/PRAD1 is the gene locus involved in the t(11;14)(q13;q32) translocation, which often occurs in a proposed subtype of non-Hodgkin's lymphoma of B-cell phenotype (B-NHL), named mantle cell lymphoma (MCL). When 67 Japanese patients with B-NHL were examined using two separate probes composed of the BCL1 MTC probe and the PRADI cDNA probe, rearrangement of BCL1/PRAD1 or overexpression of PRAD1 was detected in 11 patients. Among 13 patients with MCL, 8 had the abnormalities (61%) and the MTC probe detected the BCL1 rearrangement in 5 (38%). Five of the 6 MCL patients studied (83%) showed PRAD1 overexpression. These frequencies were compatible with those reported for Western patients. Although the remaining three with BCL1/PRAD1 abnormalities were diagnosed as having other histologies, 11 patients had advanced diseases, with dissemination to the extranodal sites. Except for one with diffuse large cell lymphoma, they had a slowly progressive disease, and none of the patients displayed clinical or pathological transformation. The tumor cells usually expressed CD5 and lacked CD10. The cells were completely uniform in the expression of IgM and/or IgD, and in the absence of C mu gene deletion. It thus appears that B-malignancies involving the BCL1/PRAD1 locus constitute a refined disease entity.

Adult↗
PubMed1993

Second-site mutation of Ala-220 to Glu or Asp suppresses the mutation of Asp-285 to Asn in the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli.

A carboxyl group of Asp-285 is essential for tetracycline/H+ antiport mediated by the transposon Tn10-encoded metal-tetracycline/H+ antiporter (TetA) of Escherichia coli (Yamaguchi, A., Akasaka, T., Ono, N., Someya, Y., Nakatani, M., and Sawai, T. (1992) J. Biol. Chem. 267, 7490-7498). Spontaneous tetracycline resistance revertants were isolated from E. coli cells carrying the Asn-285 mutant tetA gene. All of the revertants were due to the second-site mutation at codon 220 of GCG (Ala) to GAG (Glu). The Km value of the tetracycline transport mediated by the revertant TetA protein was about 4-fold higher than that of the wild-type, indicating that the revertant is a low affinity mutant. A Glu-220 and Asn-285 double mutant constructed by site-directed mutagenesis showed the same properties as the revertants, confirming that the mutation of Ala-220 is solely responsible for the suppression. The Asp-220 mutation of the Asn-285 mutant resulted in a lower level of restoration of the tetracycline resistance and the transport activity than in the case of the Glu-220 mutation. A single mutation replacing Ala-220 with Glu or Asp caused about a 2-4-fold decrease in the tetracycline resistance, but no crucial change in the transport activity. It is not likely that Glu-220 is required for a charge-neutralizing salt bridge because an unpaired negative charge in a Glu-220 or Asp-220 single mutant did not cause a serious change in the activity. An alternative explanation is reasonable; Asp-285 directly contributes to the binding of a cationic substrate, metal-tetracycline chelation complex, or proton, and an acidic residue at position 220 can take over the role of Asp-285.

Alanine↗
PubMed1993

Noninvasive assessment of left internal mammary artery graft patency using duplex Doppler echocardiography from supraclavicular fossa.

OBJECTIVES: The purpose of this study was to clarify the usefulness of duplex Doppler echocardiography from the supraclavicular fossa for assessment of left internal mammary artery graft patency. BACKGROUND: A noninvasive method to assess coronary artery bypass graft patency would be useful for clinical diagnosis and long-term follow-up of graft outcome. METHODS: Duplex Doppler echocardiography from the supraclavicular fossa was performed in 56 consecutive patients who underwent postoperative cardiac catheterization studies, including quantitative angiography. All patients underwent coronary artery bypass graft surgery using the left internal mammary artery graft to the left anterior descending coronary artery. RESULTS: The left internal mammary artery graft and its flow were detected in 55 (98%) of the 56 patients with duplex Doppler echocardiography from the supraclavicular fossa. According to the quantitative angiographic data, the patients were assigned to three groups: group A (36 patients) with a normal left internal mammary artery graft (< 50% diameter stenosis), group B (9 patients) with intermediate (50% to 75% diameter) graft stenosis and group C (10 patients) with severe (> 75% diameter) graft stenosis. The diastolic/systolic peak velocity ratio was smaller in group C than in groups A and B (p < 0.05), but there was no significant difference between groups A and B. A diastolic/systolic peak velocity ratio < 0.6 predicted severe left internal mammary artery graft stenosis (> 75% diameter stenosis) with a sensitivity and specificity of 100% and 80%, respectively. The diastolic fraction of time-velocity integral was smaller in group C than in groups A and B (p < 0.05), but there was no significant difference between groups A and B. A diastolic fraction < 0.5 predicted significant left internal mammary artery graft stenosis (> 75% diameter stenosis) with a sensitivity and specificity of 90% and 100%, respectively. CONCLUSIONS: Duplex Doppler echocardiography from the supraclavicular fossa is useful for noninvasive assessment of left internal mammary artery graft patency.

Adult↗
PubMed1993

Role of the conserved quartets of residues located in the N- and C-terminal halves of the transposon Tn10-encoded metal-tetracycline/H+ antiporter of Escherichia coli.

In the putative secondary structure of the transposon Tn10-encoded metal-tetracycline/H+ antiporter [Yamaguchi, et al. (1992) J. Biol. Chem. 267, 7490-7498], Tyr50-XXX-Gln54 in transmembrane helix 2 and Gly80-XXX-Asp84 in helix 3 are thought to face each other in the N-terminal region. At the corresponding positions in the C-terminal region, a similar quartet of residues, His257-XXX-Gln261 in helix 8 and Gly281-XXX-Asp285 in helix 9, is also located. The quartets involve the residues Asp84 and Asp285, which have been revealed to be essential for the tetracycline transport function. When Gln54 and Gln261 were replaced with Ala by site-directed mutagenesis, the active tetracycline transport activity decreased to about 10% and 40% of the wild-type level, respectively. The Km values of the Q54A and Q261A mutants for tetracycline were 140 and 160 microM, respectively, which are about 8-fold higher than that of the wild type. Thus, the two Gln residues may contribute to the substrate recognition. On the other hand, the replacement of Gly80 and Gly281 with Leu caused a complete loss of the transport activity, whereas the G80A and G281A mutants retained about 10% and 30% of the activity of the wild-type, respectively, suggesting that a bulky side chain at positions 80 and 281 causes steric hindrance of the transport. The mutation of Tyr50 to Ala or His caused a decrease in activity by a factor of about 3 without a significant change in the Km value, whereas the Y50C mutant showed no transport activity at all.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

Adult T-cell leukemia with leukemic cell infiltration in the conjunctiva. A case report.

A 77-year-old Japanese woman who had suffered from skin eruptions since 1986 was admitted in January, 1990. A diagnosis of adult T-cell leukemia/lymphoma (ATL) was made on the basis of clinical and laboratory data. On admission, erythematous lesions were present in both eyelids. Yellowish-white elevated lesions were found along the limbal conjunctiva, and extended segmentally into the cornea of both eyes. Microscopically, leukemic infiltration into the subepithelial layer of the conjunctiva was observed. Ophthalmic manifestations in ATL have not been well described, because of a little attention paid to them.

Aged↗
PubMed1993

Multiple agminated juvenile melanoma arising on a hyperpigmented macule.

A case of multiple agminated juvenile melanoma (MAJM) arising on a hyperpigmented macule is reported. The patient, a 1-year-old boy, had 9 small nodules on an irregular, hyperpigmented macule on the right shoulder. Histologically, the nodules contained nests of spindle-shaped cells in their epidermis and at the dermoepidermal junction, and the hyperpigmented macule exhibited increased melanin granules in the basal layer and small nests of epithelioid cells. We concluded that MAJM on a hyperpigmented macule is the subtype of the nevus spilus.

Humans↗
PubMed1993

Acute lymphoblastic leukemia associated with a t(1;19)(q23;p13) in an adult.

A cytogenetic study of a 38-year-old patient with acute lymphoblastic leukemia (ALL) revealed a t(1;19)(q23;p13), which is a characteristic translocation of childhood ALL. The leukemic cells were positive for the CD10, CD19, HLA-DR, TdT and cytoplasmic mu-chain. Both of the immunoglobulin heavy chain gene loci were rearranged and the RNA-based polymerase chain reaction demonstrated the E2A/PBX1 fusion transcript which is the result of the t(1;19). This finding suggests that the t(1;19) is implicated not only in childhood ALL but also in adult ALL patients.

Adult↗
PubMed1993

[Reliability of biplane transesophageal color Doppler echocardiography in evaluating mitral valve prolapse: comparison with surgical findings].

The reliability of biplane transesophageal color Doppler echocardiography for the evaluation of mitral valve prolapse was assessed by comparison with surgical findings in 27 patients. The mitral valve prolapse site was classified as the medial, central, and lateral portions of the anterior leaflet, and medial, middle, and lateral scallops of the posterior leaflet. The prolapsed sites were determined by the site of systolic displacement using two-dimensional echocardiography, the site of flow acceleration and the direction of the mitral regurgitant jet using color Doppler echocardiography. The sensitivity of transesophageal echocardiography for detecting prolapse at the medial, central, and lateral portions of the anterior leaflet, and the medial, middle and lateral scallops of the posterior leaflet was 91, 100, 86, 83, 100, and 80%, respectively. The specificity was 100, 100, 96, 100, 89, and 100%, respectively. Biplane transesophageal echocardiography is a reliable method for detecting the site of mitral valve prolapse.

Adult↗
PubMed1993

[Quantification of mitral regurgitant stroke volume by the proximal isovelocity surface area method].

Although color Doppler flow mapping has been used to quantitate the severity of mitral regurgitation, this approach has various limitations. Doppler color flow mapping of a proximal isovelocity surface area (PISA), defined by a blue-red aliasing interface, has been shown in vitro to be accurate for estimating volume flow rate across an orifice. Volume flow rate can be calculated as PISA x aliasing velocity. To evaluate the clinical applicability of the PISA method, we compared the regurgitant stroke volume estimated by the PISA method with the conventional pulsed wave Doppler method in 18 patients with mitral regurgitation. The mean systolic aliasing radius was calculated from color overlayed M-mode (Q/M-mode) images. The mitral regurgitant stroke volume calculated by the PISA method correlated well with that calculated by the pulsed Doppler method (r = 0.89, SEE = 6.0 ml). Thus, the color Doppler PISA method can be applicable to calculating the regurgitant volume in patients with mitral regurgitation.

Adult↗
PubMed1993

[Percutaneous transvenous mitral commissurotomy vs open mitral commissurotomy: evaluation of results by color Doppler and two-dimensional echocardiography].

The effects of percutaneous transvenous mitral commissurotomy (PTMC) and open mitral commissurotomy (OMC) were evaluated in 18 patients who underwent PTMC and 16 patients who underwent OMC, before and within one month of the procedure, using two-dimensional and color Doppler echocardiography. There was no significant difference between the two groups in the mitral valve area, the severity of mitral stenosis, or cardiac function before the procedure. The mitral valve area after PTMC as measured by two-dimensional echocardiography and continuous wave Doppler echocardiography increased from 1.07 +/- 0.24 cm2 to 2.01 +/- 0.42 cm2 (p < 0.001), and from 0.99 +/- 0.26 cm2 to 1.76 +/- 0.23 cm2 (p < 0.001), respectively. The mitral valve area after OMC measured by two-dimensional echocardiography and continuous wave Doppler echocardiography increased from 1.04 +/- 0.24 cm2 to 1.78 +/- 0.41 cm2 (p < 0.001), and from 0.95 +/- 0.32 cm2 to 1.62 +/- 0.46 cm2 (p < 0.001), respectively. The mitral valve areas after PTMC did not differ significantly from those after OMC by either method.

Echocardiography↗
PubMed1993

[A case of mitral valve aneurysm associated with infective endocarditis].

A case of mitral valve aneurysm associated with infective endocarditis is reported. The patient is a sixty-four year old male suffering from shortness of breath under slight exertion. He has been febrile since receiving dental treatment five months ago. The patient came to the hospital due to a continuous fever above 39 degrees C. Hematological studies suggested inflammation, and an echocardiogram revealed moderate dilatation of the left atrium, mild MR, and moderate AR. At the time of the operation, a protuberant lesion, shaped like a dome and having a size of 10 x 12 mm in diameter was found at the anterior mitral leaflet toward the left atrium. The resected specimen of the saccular lesion had a smooth surface, and the ceiling of the aneurysm was extremely thin. Microscopic study showed that the inner cavity of the lesion was covered by endothelial cells. In addition, there was granulomatous degeneration with neo-vascularization. The inferior surface of the resected valve tissue and chorda was characterized by active inflammation associated with the assembly of neutrophils and colony formation of gram-positive cocci. It was concluded that the mitral valve aneurysm was caused by weakened tissue of the anterior mitral leaflet due to sibilant inflammatory change, which resulted in protuberance of the leaflet toward the left atrium caused by left ventricular pressure.

Aortic Valve↗
PubMed1992

Serine residues responsible for tetracycline transport are on a vertical stripe including Asp-84 on one side of transmembrane helix 3 in transposon Tn10-encoded tetracycline/H+ antiporter of Escherichia coli.

Putative transmembrane helix 3 of the tetracycline/H+ antiporter encoded by a transposon, Tn10, contains four serine residues, Ser-77, Ser-82, Ser-91 and Ser-92. Each of these serine residues was replaced by site-directed mutagenesis. Of these four serine residues, Ser-77 was important for the transport function, and a bulky side chain at position 91 hindered substrate translocation, whereas Ser-82 and Ser-92 did not play any role. Ser-77 and Ser-91 are on the same vertical stripe, that includes the essential Asp-84, on the hydrophilic side of putative helix 3. These observations suggest that helix 3 is part of the tetracycline translocation channel across the membrane.

Alanine↗
PubMed1992

Metal-tetracycline/H+ antiporter of Escherichia coli encoded by transposon Tn10. Roles of the aspartyl residues located in the putative transmembrane helices.

Three conserved aspartyl residues located in the putative transmembrane helices in the Tn10-encoded metal-tetracycline/H+ antiporter were replaced by Asn, Lys, or Glu with oligonucleotide-directed site-specific mutagenesis. Replacement of Asp84 or Asp15 by Asn or Lys caused a severe defect in tetracycline transport activity, however, the Glu84 and Glu15 mutants retained 150 and 40% of the wild type activity, respectively, indicating the critical role of the negative charge. The increase in the activity of the Glu84 mutant was due to an increase in the affinity for the substrate. H+/tetracycline coupling was intact in these mutants, including Asn and Lys mutants. On the other hand, all of the Asp285-substitution mutants showed a severe defect in tetracycline transport activity and a complete lack of tetracycline-coupled H+ transport. However, since in vivo tests showed the tetracycline resistance for the Glu285 mutant, a negative charge in position 285 plays some role in maintaining the possible down-hill and/or low affinity efflux of accumulated tetracycline from intact cells. Similar work was done for Asp365, and here the Asn and Glu mutants showed decreased but high activity, while the Lys mutant was only marginally active (5%), indicating that a negative charge is not so demanding in position 365, possibly because it is not in the membrane.

Amino Acid Sequence↗
PubMed1992

Value of acceleration flow signals proximal to the leaking orifice in assessing the severity of prosthetic mitral valve regurgitation.

To test the value of acceleration flow signals proximal to the leaking orifice in assessing the severity of prosthetic mitral valve regurgitation, 39 consecutive patients undergoing left ventriculography were examined by Doppler color flow imaging. Acceleration flow signals proximal to the regurgitant orifice were detected in 27 of the 31 patients who had prosthetic mitral regurgitation by left ventriculography (sensitivity 87%). All four patients without acceleration flow signals had mild prosthetic mitral regurgitation by angiography. No acceleration flow signals were detected in any patient without prosthetic regurgitation by left ventriculography (specificity 100%). Individual values of the maximal area of acceleration flow signals obtained from three orthogonal planes in seven patients with mild prosthetic mitral regurgitation by angiography ranged from 0 to 17 mm2 (mean 4 +/- 6). In 8 patients with moderate prosthetic mitral regurgitation by angiography, the maximal area of acceleration flow signals ranged from 21 to 58 mm2 (mean 33 +/- 15), whereas the maximal area of acceleration flow signals in 16 patients with severe prosthetic regurgitation ranged from 20 to 173 mm2 (mean 102 +/- 41). The maximal area of the acceleration flow signals from three planes correlated well with the angiographic grade of prosthetic mitral regurgitation. There was a significant difference in the maximal area of acceleration flow signals between mild and moderate (p less than 0.001), moderate and severe (p less than 0.001) and mild and severe (p less than 0.001) prosthetic mitral regurgitation. Thus, measurement of acceleration flow signals by Doppler color flow imaging is useful in assessing the severity of prosthetic mitral regurgitation.

Bioprosthesis↗
PubMed1992

Microcomputer-based automatic regulation of extracorporeal circulation: a trial for the application of fuzzy inference.

Since its establishment many researchers have been trying to automate the process of extracorporeal circulation (ECC). We developed a preliminary experimental model of an automatic regulatory system for ECC. The purpose of the system was to regulate basic hemodynamic parameters such as pump flow and withdrawal blood volume. It was divided into three main components: data sampling unit, central processing unit, and controlling unit. Based on this model we were able to achieve autoregulation of ECC using minimum configuration; however, the system lacked smoothness. This was partly because it was based on a "static" regulation system which used conditional statements having multiple parameters. In this study, we applied fuzzy logic to the former model to achieve more accurate and reliable regulation. We report experimental results for the new system and compare the data between clinical circulation in 13 infants (mean body weight, 13.32 +/- 5.99 kg) and experimental regulation in 7 mongrel dogs (mean body weight, 11.9 +/- 2.53 kg). The comparative study revealed no statistical difference between the two groups. This result suggests that the automatic regulation of ECC may be an alternative to manual operation by a professional perfusionist in the near future.

Animals↗
PubMed1992

Obstruction of inferior vena caval orifice by giant left atrium in patients with mitral stenosis. A Doppler echocardiographic study from the right parasternal approach.

BACKGROUND: To examine whether an extremely enlarged left atrium (giant left atrium) obstructs the venous return from the inferior vena cava (IVC), the velocity of IVC flow was measured at its junction with the right atrium (IVC orifice) in patients with mitral stenosis by use of color and pulsed-wave Doppler echocardiography from a right parasternal longitudinal plane. METHODS AND RESULTS: The maximum dimension of the IVC orifice by two-dimensional echocardiography and the maximum IVC orifice flow velocity by pulsed-wave Doppler echocardiography were measured in 74 patients with mitral stenosis and atrial fibrillation (mean age, 59 years). The control population consisted of 16 subjects with atrial fibrillation alone (mean age, 61 years). Flow velocities in the superior vena cava and hepatic vein were also obtained by pulsed-wave Doppler echocardiography from the supraclavicular and subcostal views, respectively. Fifty-one mitral stenosis patients without severe tricuspid regurgitation were divided into two groups according to the left atrial dimension (LAD), which was measured by the standard left parasternal long-axis view (group A: n = 33, LAD less than 65 mm; group B: n = 18, LAD greater than or equal to 65 mm). Peak inspiratory and expiratory velocities of IVC orifice flow in diastole averaged over three consecutive inspirations in group B (mean +/- SD, 93.4 +/- 32.0 and 47.6 +/- 19.8 cm/sec) were significantly greater (p less than 0.01) than in the control subjects (67.9 +/- 12.8 and 34.5 +/- 7.0 cm/sec) and in group A (70.2 +/- 18.4 and 38.1 +/- 11.5 cm/sec, respectively). However, there were no significant differences in superior vena caval and hepatic vein flow velocities among the three groups. The maximum IVC orifice dimension in group B (11.4 +/- 4.4 mm) was significantly smaller than in the control subjects (20.1 +/- 2.1 mm) and in group A (18.6 +/- 5.4 mm) because of displacement of the atrial septum into the right atrium. There were significant negative correlations between the IVC orifice dimension and the peak IVC orifice flow velocity (r = -0.62, SEE = 0.33 cm/sec, n = 67, y = e(-0.01x + 3.6), p less than 0.01) as well as the left atrial dimension (r = -0.71, SEE = 0.32 mm, n = 67, y = e(-0.02x + 3.8), p less than 0.01) in these 51 patients and control subjects. In the remaining 23 patients with severe tricuspid regurgitation, the peak inspiratory IVC orifice velocity (n = 9, 88.6 +/- 30.0 cm/sec) was significantly greater (p less than 0.05) and the IVC orifice dimension (23.8 +/- 9.7 mm) significantly smaller (p less than 0.05) in patients with a giant left atrium than in those without (n = 14, 69.9 +/- 15.3 cm/sec and 30.5 +/- 9.6 mm, respectively); in the latter, the IVC orifice dimension was significantly (p less than 0.05) greater than in the controls. CONCLUSIONS: A giant left atrium in patients with mitral stenosis obstructs venous return at the IVC orifice by marked displacement of the atrial septum toward the right atrium.

Adult↗