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Biomedical subjects

S Takamoto

Publications and source records attributed to S Takamoto.

At least 235 records · Page 13Linked to original sources
PubMed1990

Early diagnosis and surgical intervention of acute aortic dissection by transesophageal color flow mapping.

To determine whether transesophageal color Doppler echocardiography (TEE) is useful for the early diagnosis and surgical intervention in acute aortic dissection, 57 serial patients with acute aortic dissection were examined. These patients were evaluated by TEE with either the single-plane probe (39 patients) or the biplanar probe (18 patients) just after admission. The intimal flap was detected in all patients, and there were 18 patients with type A dissection and 39 patients with type B dissection. The entry was visualized in 83% of type A dissection cases and in 90% of type B dissection cases. In two of 18 patients examined with the biplanar probe technique, the entry was detected in the longitudinal view only. Emergency operations were performed in 18 patients with type A dissection and in 10 patients with ruptured type B dissection. Twenty-nine of 39 patients with type B dissection were treated conservatively. The operative mortality rate of patients with type A dissection was 22%, and that of patients with ruptured type B dissection was 60%. The major advantage of TEE is its ease of application at the bedside or in the operating room, which allows immediate and accurate diagnosis of acute aortic dissection for emergency surgical intervention. Biplanar TEE provides additional acoustic windows, ease of spatial orientation, and more accurate visualization of entry. TEE is a useful and powerful diagnostic tool for acute aortic dissection, and by using this method, one may achieve a more rapid and aggressive surgical approach for patients with acute aortic dissection.

Acute Disease↗
PubMed1989

Effects of valinomycin on calcium mobilization in vascular smooth muscle cells induced by angiotensin II.

The effect of the specific potassium (K+) ionophore valinomycin on increase in intracellular calcium concentration [( Ca2+]i) was studied in vascular smooth muscle cells (VSMC). Valinomycin at more than 10(-9) M dose-dependently suppressed phasic increase in [Ca2+]i in VSMC induced by angiotensin II (AII) in both control and Ca2+-free solution, indicating that it suppressed the release of Ca2+ from intracellular Ca2+ stores. Nicorandil and cromakalim, which are both K+ channel openers, also suppressed the increases in [Ca2+]i induced by AII in the Ca2+ free solution. However, valinomycin did not suppress AII-induced production of inositol 1,4,5-trisphosphate (IP3), which is known to mediate the release of Ca2+. These results indicate that decrease of intracellular K+ induced by valinomycin suppressed the release of Ca2+ from intracellular Ca2+ stores induced by IP3.

Angiotensin II↗
PubMed1989

[Responses of aortocoronary bypass graft flow to nitroglycerin, nifedipine and exercise test: a two-dimensional color Doppler echocardiographic study].

To assess the effects of coronary vasodilators and exercise on the blood flow dynamics of aortocoronary bypass grafts (ACBG), two-dimensional Doppler echocardiography was performed in 43 consecutive patients with ACBG of the left coronary artery. Doppler velocity signals of 14 internal mammary artery grafts (IMAG) and three saphenous vein grafts (SVG) were imaged in 15 patients using 5MHZ and 7.5MHZ convex-linear Doppler flow probes. Cross-sectional blood flow velocities and graft internal dimensions were continuously measured before and after the sublingual administration of nitroglycerin (0.3 mg) and nifedipine (20 mg), during isometric handgrip and bicycle ergometer exercise tests. 1. Regurgitant flow in isometric contraction time to early systole was observed in 14 of the 15 patients. Pulsatile diastolic blood flow with mean velocity of 14 +/- 6 cm/sec and volume of 49 +/- 25 ml/min was significantly higher than those in systole (7 +/- 7 cm/sec and 8 +/- 7 ml/min) as observed in IMAG and SVG. IMAG showed smaller vessel dimensions, higher flow velocities and lower flow volumes compared with those of SVG. 2. Nitroglycerin and nifedipine increased blood flow volumes (75 +/- 12%, 79 +/- 11%) and velocities (29 +/- 8%, 28 +/- 8%) due to dilatation of graft vessels (18 +/- 3%, 19 +/- 3%). Nifedipine, in contrast to nitroglycerin, induced sustained increases in graft flows. 3. Isometric handgrip and ergometer bicycle exercise tests increased blood flow volumes (34 +/- 9%, 61 +/- 14%) and velocities (31 +/- 11%, 42 +/- 12%) with elevation of double products (22 +/- 14%, 37 +/- 26%). Ergometer bicycle exercise induced similar responses in systole and diastole, whereas isometric handgrip test induced higher ratios of graft flow volume in systole (67 +/- 25%) compared to those in diastole (28 +/- 9%). In conclusion, two-dimensional color Doppler echocardiography is a promising means for the quantitative analysis of blood flow dynamics, assessments of the variable effects of coronary vasodilators and the physiological responses to exercise tests for the aortocoronary bypass graft flow in the early postoperative state.

Aged↗
PubMed1989

[Analysis of DNA aneuploidy as a tumor marker].

Cellular DNA content was determined by flow cytometry for 185 adult cases with various types of leukemia. DNA aneuploidies (DA) were detected in 50 of 185 patients (27%). Incidences of DA in subtypes of leukemia were as follows: 26% in acute lymphocytic leukemia (ALL), 17% in acute non-lymphocytic leukemia (ANLL), 28% in chronic myelocytic leukemia in blastic crisis (CML-BC), 6% in chronic lymphocytic leukemia and 55% in adult T-cell leukemia (ATL). Among subtypes, the incidence in ATL was significantly high (p less than 0.01), which suggested the special entity of this disease. No differences of incidence were found between male and female patients. DNA index (DI) ranged between 0.913 and 2.042, and the mean value was 1.144. Hypodiploid clones were detected in two cases (4%) and the rest of cases all showed hyperdiploid clones. Also only in two cases (4%), two abnormal DNA stemlines were detected, which suggested the low incidence of heterogeneous population in leukemic cells. In a few cases , whom we were able to follow up the clinical course, we could detect the early relapse in advance to morphological diagnosis and identify the "recruitment" of leukemic cells with the use of DA as a tumor marker. With regards to the prognosis of patients, DA was found to be useful as an unfavorable prognostic factor in ANLL (p less than 0.01) as well as in CML-BC (0.05). These data showed a clinical usefulness of flow cytometric analysis of DNA aneuploidy as a tumor marker. Moreover, based on our results, the usefulness of flow cytometric analysis of DA was discussed, with reference to current studies on leukemias and solid tumors.

Aneuploidy↗
PubMed1989

[Visualization of internal mammary artery bypass graft flow using a linear color flow mapping system with a convex type transducer].

To evaluate noninvasively the patency of aortocoronary bypass grafts using the left internal mammary artery (LIMAG), color flow mapping Doppler echocardiography was performed in 23 consecutive patients. There were 22 males and one female. The average number of involved coronary arteries per patient was 2.5 +/- 0.6. The average number of bypassed graft anastomoses was 2.7 +/- 0.9, including 22 isolated LIMAG and one sequential LIMAG. The color flow mapping system used was a linear type 2-D Doppler system (Aloka SSD350) with a convex type transducer. Clear color flow visualization of LIMAG flow was obtained in nine of the 23 patients (39%) studied, with an average peak diastolic velocity of 22.5 +/- 8.7 cm/sec and an average systolic peak velocity of 12.6 +/- 5.7 cm/sec. The coronary angiograms of eight patients were obtained within two weeks after the echocardiographic examinations which demonstrated good graft patency in all LIMAG. Color flow visualization of LIMAG was obtained in four of the eight patients (50%). Although the detection rate was limited, LIMAG flow could be clearly visualized in nearly half the cases studied with stable reproducibility from the transcutaneous echo window. Thus, this technique can be a useful diagnostic means for long-term follow-up of LIMAG and for investigating coronary circulation in the future.

Aged↗
PubMed1988

Effect of estrogens on renal responsiveness to parathyroid hormone in elderly female subjects.

The effect of estrogens on the renal responsiveness to parathyroid hormone (PTH) was examined by PTH loading tests with synthetic human-PTH (1-34) in 8 normal elderly females (mean +/- SD age, 81.0 +/- 7.1 yr) before and after administration of estrogen (Premarin 1.25 mg/day for 4 weeks). Basal urinary adenosine cyclic 3', 5'-monophosphate (cAMP) excretion showed a tendency to increase after estrogen administration (5.47 +/- 1.68 vs 6.60 +/- 2.67 nmol/100 ml GFR) and the theoretical renal phosphorous threshold showed a tendency to decrease from 3.22 +/- 0.98 to 2.73 +/- 0.56 mg/dl. The blood ionized calcium concentration did not change after estrogen administration (4.44 +/- 0.16 vs 4.32 +/- 0.20 mg/dl) and serum phosphorous (P) decreased significantly (3.65 +/- 0.47 vs 3.01 +/- 0.42 mg/dl, p less than 0.05). There was no increase in mean serum immunoreactive PTH (0.34 +/- 0.10 vs 0.34 +/- 0.05 ngeq/ml). The urinary excretions of cAMP in response to PTH loading [100 U of human-PTH (1-34), intravenously] significantly (p less than 0.05) increased (94.8 +/- 57.0 vs 196.7 +/- 118.3 nmol/100 ml GFR/h) after estrogen administration. Moreover the changes in urinary excretion of cAMP (r = 0.698, p less than 0.01) and P (r = 0.555, p less than 0.05) induced by the PTH loading were positively correlated with serum estradiol in elderly females, assessed as groups before and after estrogen administration. These results suggest that estrogens may enhance the renal responsiveness to exogenous PTH administration.

Adult↗
PubMed1988

A patient with hypogonadotropic hypogonadism successfully treated by long-term pulsatile administration of luteinizing hormone-releasing hormone.

A male patient with hypogonadotropic hypogonadism has been treated by pulsatile administration lf luteinizing hormone-releasing hormone (LHRH) (20-25 micrograms, every 2 hours, sc) for 4 years 6 months. His plasma testosterone (T) concentration began to increase after 4 weeks of treatment and reached the normal range in week 5. He showed complete secondary sexual development after 1 year of treatment. His sperm count was normalized after 1 year of treatment. He was married after 29 months of therapy, and has a healthy male child. Blood type tests showed his paternity of the child. During the long duration of pulsatile LHRH therapy, his gonadotropin secretion has been stimulated by LHRH and his T level has been maintained with no observable side effects. There are no other reports of patients treated by pulsatile LHRH injection for such a long duration, but finding in this patient indicated that long-term pulsatile LHRH therapy is a useful and safe method for treatment of hypothalamic hypogonadotropic hypogonadism.

Adult↗
PubMed1988

Functional and morphological differentiation induction of a human megakaryoblastic leukemia cell line (MEG-01s) by phorbol diesters.

The effect of differentiation induction by a tumor-promoting phorbol diester, 12-O-tetradecanoylphorbol-13-acetate (TPA) on a clonal human megakaryoblastic cell line, MEG-O1s, was investigated, and a prominent response was demonstrated. The cells became weakly adherent, developed conspicuous cytoplasmic blebs, and displayed mature megakaryocytic characteristics by light microscopy such as the development of azurophilic cytoplasmic granules and a mosaic pattern of oxyphilic patches, multiplication of nuclei, and enhancement of the PAS reaction and alpha-naphthyl acetate esterase staining. Ultrastructural studies demonstrated the development of prominent cytoplasmic blebs, budding of blebs, and multiplication of nuclei. Numerous granules with central nucleoids that are similar to alpha granules had developed as well as granules with high electron density and clearly demarcated zones. Surface marker analysis revealed a moderate increase in IgG Fc receptor levels and a profound decrease in C3 receptor sites. By an immunofluorescent technique using monoclonal and polyclonal antibodies, a dramatic change in the expression of several megakaryocyte-platelet-specific proteins was demonstrated. All the proteins that had been expressed before induction such as platelet glycoprotein (GP) IIb/IIIa, fibrinogen, von Willebrand factor, factor XIIIA, beta-thromboglobulin (beta-TG), and HLA class 1 antigen were profoundly enhanced after induction by TPA. Induction by TPA led to the expression of fibronectin and factor V, which were not detected on nontreated cells. An ultrastructural immunoperoxidase study demonstrated platelet GPIb and GPIIb/IIIa in both plasma membranes and protein synthesis areas such as perinuclear cisternae and endoplasmic reticulum after TPA induction. beta-TG was also observed in some cytoplasmic granules of TPA-treated cells. TPA remarkably increased the secretion of beta-TG into the culture medium of MEG-01s. Ploidy was also increased from 2C to 4C to 4C to 8C. Similar maturation of MEG-01s was induced by other phorbol diester analogues such as phorbol-12,13-dibutyrate, but not by phorbol itself. These results indicate that phorbol diester, TPA, can bring about differentiation and maturation of a human megakaryoblastic cell line (MEG-01s) and that MEG-01s cells will provide a useful model for studying megakaryocytic differentiation and numerous megakaryocyte-platelet-specific proteins.

Antibodies, Monoclonal↗
PubMed1988

[Study of the effect of antitumor agents on cell cycle traverse by flow cytometry].

The effect of antitumor agents on the cell cycle traverse of cultured FL cells, a monolayer culture line derived from human amnion, was investigated by flow cytometry (FCM) in combination with simultaneous determination of total cell number, viability, mitotic index and labeling index by [3H]TdR. The results obtained can be summarized as follows: Antimetabolites prolonged the duration of the S phase at a low dose, while at a high dose they decreased the rate of progression from the G1 to S phase, resulting in G1 and G1-S boundary accumulation. Partial synchronization by these agents was obtained through two different mechanisms. In vinca alkaloid-accumulated cells in the G2+M phase at 24h, mitotic index (MI) reached 20%, which was 10 to 20 times higher than that of control and most M-phase cells, which consisted of metaphase cells. Other cells in a tetraploid state were considered to be in the G2 phase or possibly G1 phase of the tetraploid cycle. Antibiotics generally accumulated cells in the G2 phase, but agents could be divided into two groups according to the degree of G2 accumulation. One group showed almost complete G2 accumulation, while the other showed only partial accumulation. The former group inhibited the progression of the S phase at a higher dose. Both groups completely inhibited the progression of the cell cycle at the highest dose. Alkylating agents only partially accumulated cells in the G2 phase at a low dose, showed prolongation of the S phase at a high dose, and inhibited the progression of the cell cycle at the highest dose, as with antibiotics. On the basis of these results, the application of these agents for treatment of cancer, especially leukemia, is discussed from a rational viewpoint.

Alkylating Agents↗
PubMed1987

Hydroxylation of 25-hydroxyvitamin D3 by renal mitochondria from rats of different ages.

The hydroxylation of 25-hydroxyvitamin D3 (25OHD3) in kidney mitochondria from female rats of different ages was studied. The specific activity of 1 alpha-hydroxylase was highest in mitochondria isolated from the 2-month-old rat (0.47 pmol/10 min X mg protein), falling gradually with age to 0.17, 0.10, 0.07, and 0.06 pmol/10 min X mg protein in 6-, 12-, 18-, and 24-month-old rats, respectively. The alteration in 1 alpha-hydroxylase activity with age was due to a change in the V'm of the system; the K'm for 25OHD3 was unchanged (3.9-4.0 microM). The specific activity of 24-hydroxylase was lowest in mitochondria isolated from the 2-month-old rat (8.2 pmol/10 min X mg protein), increasing to 37.8, 37.4, 38.2, and 55.7 pmol/10 min X mg protein in 6-, 12-, 18-, and 24-month-old rats, respectively. The alteration in 24-hydroxylase activity with age was due to a change in the V'm of the system; the K'm value for 25OHD3 was unchanged (1.1-1.2 microM). The age-dependent decrease in 1 alpha-hydroxylase and concomitant increase in 24-hydroxylase activities observed in mitochondria isolated from kidneys of 2-, 6-, 12-, 18-, and 24-month-old rats could not be attributed to changes in the bioenergetic properties, i.e. the respiratory chain, of the mitochondria. The relative mitochondrial content of the kidney, however, probably decreased with age. These findings support the view that the kidneys of aged rats produce less 1,25-dihydroxyvitamin D3 because of lower mitochondrial 1 alpha-hydroxylase specific activity and reduced number of mitochondria. This would be consistent with the lower levels of vitamin D hormone reported in the serum of senescent rats.

24,25-Dihydroxyvitamin D 3↗