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Biomedical subjects

I Takeuchi

Publications and source records attributed to I Takeuchi.

At least 91 records · Page 5Linked to original sources
PubMed1989

Structure and expression of elongation factor 2 gene during development of Dictyostelium discoideum.

A cDNA library constructed from poly(A)+ RNA isolated from Dictyostelium discoideum cells at 12 h of development was screened with the hamster elongation factor 2 (EF-2) cDNA. Several different cDNA clones which hybridized were isolated after a second screening. A cDNA clone representing the 5'-end of the mRNA was obtained by primer extension. By comparing the amino acid sequence deduced from the nucleotide sequences of these clones with that of hamster EF-2, we found enough homology between them to conclude that the isolated clones were complementary to the mRNA of D. discoideum EF-2. The N terminus which is the GTP-binding domain and the C-terminal half where it interacts with a ribosome showed a high degree of homology. The amino acid sequence of the carboxyl half includes that it contain a site of ADP-ribosylation by diphtheria toxin. From the Northern blotting analysis, the size of the mRNA was estimated to be 2.6 kilobases. The expression of the mRNA was high in vegetative cells, became maximal at the aggregation stage, and decreased thereafter through development. Upon differentiation of prespore and prestalk cells, the mRNA was highly enriched in the former over the latter. ADP-ribosylation assay of EF-2 protein by diphtheria toxin showed nearly the same developmental changes for the protein as the mRNA. However, prestalk cells were found to contain the same amount of the protein as prespore cells. The Southern blot analyses indicated that the gene encoding EF-2 is unique.

Amino Acid Sequence↗
PubMed1989

Recanalization of intracranial carotid occlusion detected by duplex carotid sonography.

We studied three patients with internal carotid artery occlusion at the siphon who had recanalization during 1 month of close observation. Angiography and duplex carotid sonography (DCS) were repeated serially in each patient. Blood flow patterns detected by DCS were classified into three patterns by specific angiographic changes. The distal occlusive flow pattern on DCS corresponds to internal carotid artery occlusion at the siphon angiographically, the median flow pattern on DCS corresponds to partial recanalization, and a normal flow pattern on DCS indicates almost complete recanalization. Since DCS can be easily repeated, the exact time of recanalization can be determined noninvasively. In all three patients, hemorrhagic infarction observed on computed tomograms occurred at the time of recanalization detected by DCS. DCS demonstrates that recanalization is one of the mechanisms of hemorrhagic infarction.

Aged↗
PubMed1989

[Bypass operation adaptable to stature increase in child with atypical coarctation of the aorta].

A 9-year-old girl was admitted with hypertension and severe congestive heart failure. Upon physical examination, a discrepancy of blood pressure between arm and leg was noted. Aortography revealed narrowing about 5 cm in length at the midportion of the descending thoracic aorta. Bypass operation of the narrow segment was performed under mild hypothermia with the diagnosis of atypical coarctation of the aorta. It was supposed that the patient might outgrow the graft and the graft would become too small for grown-up patient in diameter and length, then the haemodynamics would become less satisfactory and too much tension on the suture line would occur. A woven Dacron graft, 10 mm in diameter, 15 cm in length, was anastomosed proximally and distally to the coarcted segment at a distance of about 6 cm. So, the graft was disposed in a C-shaped configuration. It was expected that the arch of the graft would open more widely with increase of her stature, even if the graft does not increase in length. She has been followed for twelve years. Hypertension of upper extremity and arm-to-leg gradients of the systolic blood pressure were recognized from two years after the operation, particularly with exercise. However, cardiomegaly and left ventricular hypertrophy in ECG were improved. She appears to have been developing normally with no cardiac symptoms. Estimating from angiography, the distance between proximal and distal anastomoses stretched about 2 cm during the period of rapid growth, though calcification of the graft had been seen from four years after the operation, perhaps due to increased calcium turnover in childhood.

Aorta, Thoracic↗
PubMed1988

Structural requirements of salicylanilides for uncoupling activity in mitochondria: quantitative analysis of structure-uncoupling relationships.

The uncoupling activities of more than 20 salicylanilides were measured in rat liver mitochondria. The activities, expressed as the minimum concentrations required for full release of state-4 respiration, ranged over three orders of magnitude. The acid dissociation constant, pKA, and the partition coefficient between octanol and water (Poct) of some of the salicylanilides were determined. These two parameters were found to be well expressed in terms of the Hammett constant, sigma, and the hydrophobic substituent coefficient, II, respectively. The pKA and log Poct values of all the salicylanilides were predicted according to these relationships. Furthermore, the capacity factor, k', on high-performance liquid chromatography was determined on glyceryl-coated-controlled pore glass (gly-CPG). Values of log k' correlated well with those of log Poct. The uncoupling activities of the salicylanilides were analyzed in terms of these three parameters. Both hydrophobic and electron-withdrawing properties were found to be essential for induction of potent uncoupling activity. The correlations using log k' were better than those using log Poct.

Animals↗
PubMed1988

Cell behavior during formation of prestalk/prespore pattern in submerged agglomerates of Dictyostelium discoideum.

When cells dissociated from Dictyostelium discoideum slugs were cultured in roller tubes, they formed agglomerates in which prestalk cells were initially dispersed but soon sorted out to the center and then moved to the edge to reconstitute the prestalk/prespore pattern. To examine the mechanism of sorting out, individual prestalk cells were traced by a videotape recorder. The radial component of the rate of movement toward the center of the presumptive prestalk region was calculated. Prestalk cells did not move randomly, but rather directionally toward the center. Their movement was pulsatile, with a period of ca. 15 min, and accompanied by occasional formation of cell streams, thus resembling the movement observable during cell aggregation. These results favor the idea that prestalk cells sort out to the prestalk region due to differential chemotaxis rather than differential adhesiveness. After formation of the prestalk/prespore pattern, the prestalk region rotated along the circumference of the agglomerates. This appears comparable to migration of slugs on the substratum, the rate of rotation being similar to that of slug migration. To examine the processes of pattern formation during development, washed vegetative cells were cultured in roller tubes. Prespore cells identified by antispore immunoglobulin initially appeared randomly within the agglomerates, but then nonprespore cells accumulated in the center and finally moved to the edge to establish the prestalk/prespore pattern, the processes being similar to those of pattern reconstruction with differentiated prestalk and prespore cells.

Cell Aggregation↗
PubMed1988

Dose-dependent hypolipidemic effect of an inhibitor of HMG-CoA reductase, pravastatin (CS-514), in hypercholesterolemic subjects. A double blind test.

The hypolipidemic effect of a new HMG-CoA reductase inhibitor, pravastatin, was examined. The reductions of serum cholesterol and LDL-cholesterol were dose-dependent and significant differences were observed between placebo and 10 or 20 mg groups (P less than 0.01), and 10 and 20 mg (P less than 0.05) groups. The reduction rate of cholesterol after 8 weeks during medication was 16.1% in the 10 mg group, 20.5% in the 20 mg group compared to baseline serum cholesterol levels. LDL-cholesterol decreased by 23.9% in the 10 mg group, and 29.8% compared to baseline LDL-cholesterol in the 20 mg group. The lowering of total cholesterol was entirely attributed to a reduction in LDL-cholesterol.

Adult↗
PubMed1988

Molecular cloning of cell-type-specific cDNAs exhibiting new types of developmental regulation in Dictyostelium discoideum.

By screening cDNA libraries from NC-4 cells, we have obtained five prespore-specific and two prestalk-specific cDNA clones. The two classes of prespore genes began to be expressed at the tipped aggregate stage: one class was expressed throughout development, while the other was shut off during culmination. Another class of prespore genes was expressed in vegetative cells but only in prespore cells at the later stages. Prestalk-specific genes were first expressed at the tipped aggregate stage concurrently with the two prespore gene classes, indicating the importance of this stage for transcriptional regulation in both prestalk and prespore differentiation. Except for the first prespore gene class, these represent new cell-type-specific genes as to their temporal pattern of expression.

Cloning, Molecular↗
PubMed1988

Effects of ketanserin tartrate on serum lipids in patients with essential hypertension.

Several antihypertensive agents such as thiazide diuretics and some beta-blockers have recently been shown to adversely affect lipid metabolism. Moreover, there is a growing suspicion that the adverse effect on plasma lipids might outweigh the favourable effect of lowering blood pressure. The effect of ketanserin tartrate (20 to 60 mg daily), a new antihypertensive drug, on blood lipids was evaluated in a 12-week non-comparative clinical trial in 34 patients with mild or moderate hypertension. Ketanserin reduced systolic and diastolic blood pressure by 12.2 and 9.8%, respectively, without altering heart rates. Total cholesterol and low density lipoprotein (LDL)-cholesterol levels in the fasting plasma were observed to decrease significantly by 6.3 and 8.8% respectively, whereas mean triglyceride and high density lipoprotein (HDL)-cholesterol remained almost unchanged. These changes were consistent irrespective of their initial values. Significant decrease in apolipoprotein B and E was also observed. Apolipoprotein A-I, A-II, C-II and C-III were not altered significantly. It is speculated that ketanserin affects mainly LDL-cholesterol. Based on these findings, ketanserin is considered to have a potentially beneficial effect on coronary risk profile and should be given full consideration when drug therapy is selected for patients with mild to moderate hypertension.

Adult↗