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Biomedical subjects

I Takeuchi

Publications and source records attributed to I Takeuchi.

At least 73 records · Page 4Linked to original sources
PubMed1993

Developmental regulation of transcription of a novel prespore-specific gene (Dp87) in Dictyostelium discoideum.

The Dp87 is a novel prespore specific gene of Dictyostelium discoideum which has a long open reading frame of 555 amino acids. The entire amino acid sequence had low but significant homology to the spore coat proteins, SP96 and SP70, of this organism. When a chimeric gene, containing a 1380 bp of the 5' upstream region of this gene fused with CAT gene, as reporter, was introduced into cells of this organism, it was expressed only in prespore cells of the slug. Transformation experiments, using chimeric genes, containing a series of 5' deletions of the upstream region, showed that -447 bp to -357 bp is an important cis-acting regulatory region for transcription. A nuclear factor(s) that specifically bind to this cis-acting region were detected from slug cell nuclei. Transformation experiments using a chimeric gene consisting of the 5' region between -666 bp and +149 bp of this gene, a beta-galactosidase reporter and an actin 8 terminator, showed that the reporter gene was expressed as early as in aggregation streams, indicating that Dp87 become transcribed a few hours earlier than the other prespore-specific genes so far reported. This was confirmed by northern hybridization detected using an image plate analyzer. The fact that cells expressing Dp87 appeared at random in aggregation streams gives solid support to the idea that position-independent differentiation of prespore and prestalk cells, followed by their sorting, brings about pattern formation in this organism.

Amino Acid Sequence↗
PubMed1992

Protein binding and DNase-I-hypersensitive sites in the cis-acting regulatory region of the spore-coat SP96 gene of Dictyostelium.

The spore-coat protein gene (SP96) of Dictyostelium discoideum is transcribed only in prespore cells. To identify the cis-acting region of this gene, mutant mini-genes which contained different lengths of 5' upstream region, the partially deleted SP96 coding region and ca. 600 bp of 3' flanking sequence were transformed into D. discoideum cells. Expression of the mini-genes was analysed by Northern hybridization. Our results indicate that the 5' upstream region from -686 to -494 contains an important cis-acting element for the temporal and cell type-specific transcription. A nuclear factor which specifically bound the cis-acting region was identified by gel retardation assay. DNase-I-hypersensitivity of the 5' upstream region was examined and it was shown that the appearance of two new hypersensitive sites correlates with transcriptional activation of the gene. One of the two sites maps to the TATA region and the other was located in the cis-acting region identified by deletion analysis. Our results suggest that gene activation occurs by conformational changes in the chromatin structure of the cis-acting region followed by subsequent binding of regulatory factors and the TATA-binding protein.

Animals↗
PubMed1992

[Study in predictive posture control during the performance of actions].

In order to maintain an ordinary upright posture, the body's center of gravity must be predicted and controlled on the supporting surface based on synthesis of multiple-sensory inputs. In order to evaluate the accuracy of predictive (feedforward) posture control during the performance of actions, we measured maximal shifts in the body's center of gravity using a force platform in 6 normal adults under two visual conditions (with eyes open and closed) and four standing conditions (one-legged; heel to toe posture; and both legs together or apart). Subjects were asked to perform five kinds of voluntary actions (static standing; head tilting forward, backward and laterally; head turning; bending forward; and maximal inclinations to the anterior, posterior and lateral directions). The smaller the supporting surface, the more markedly displacement of the body's center of gravity was increased upon closing the eyes. This finding suggests that the accuracy of predictive posture control decreases as a result of the reduction in the number of multisensory inputs which determine spatial orientation. Assessing purposive shifts in center of gravity during voluntary actions, we can conclude that the body's center of gravity is accurately controlled even in the presence of head movements under ordinary standing conditions. To evaluate balance during the performance of routine actions, we must devise a better method of discriminating purposive shifts in center of gravity from control disorder errors as well as a method of quantifying the accuracy of feedforward regulation.

Adult↗
PubMed1992

[Study of 54 renal allograft recipients in the cyclosporin A era. What influences acute rejection episode and long-term graft survival?].

During the past 5-year period from 1986 to 1991, a total of 54 patients received living-related renal allograft and has been managed with vagaries of cyclosporin A (CYA) immunosuppressive regimen. In order to determine the ideal form of induction regimen, combination drugs with CYA, the initial dosage of CYA and its blood trough level were retrospectively analyzed with particular reference to the possible factors relevant to the occurrence of acute rejection episode in the first three post-transplant months and graft survival. The combination drugs with CYA were prednisolone (PRD) in 10 patients, PRD + azathioprine (AZA) in 19 and PRD+mizoribine (MIZ) in 25. The initial dosage of CYA was 6 mg/kg B.W. in 6 patients, 8 mg/kg in 17, 10 mg/kg in 15 and > or = 12 mg/kg in 16. Blood trough level of CYA measured principally by high performance liquid chromatography was arbitrarily divided into < 100, 100-150, 150-200, > or = 200 mg/kg ranges for the analysis. By arbitrarily dividing the post-transplant period into four (period I: 0-15th day, period II: 16-30th, period III: 31-60th and period IV: 61-90th), the correlation of the incidence of acute rejection episode and aforementioned factors was studied. Relevance of these factors to the graft survival was also studied. The administration of AZA to MIZ to CYA + PRD had no suppressive effect upon the occurrence of acute rejection during the first three months and similarly it had no effect upon graft survival. Rejection episodes, however, occurred more frequently in the recipients with less than 150 ng/ml of CYA trough level in the period I and less than 100 ng/ml in the period III (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

[A case of posterior choroidal artery infarction].

The posterior choroidal artery supplies the lateral geniculate body, the posterior thalamus and the caudate body. Currently, a few cases of infarction in this arterial territory have been reported. This is a case of 59-year-old male, exhibiting left homonymous hemianopsia and left hemiparesis. Clinically it was impossible to make a diagnosis of infarction in this area. We were able to determine that it was a posterolateral choroidal artery infarction rather than an anterior choroidal artery infarction using 1.5 T-magnetic resonance imaging (MRI). The MRI scan clearly disclosed the areas of infarction, which included the lateral geniculate body, the posterior thalamus and the caudate nucleus body. Additionally, cerebral angiography revealed an occluded proximal portion of the right posterior cerebral artery (P2) and a patent right anterior choroidal artery. Anatomically, the areas surrounding the lateral geniculate body are supplied by both the anterior and the posterolateral choroidal arteries. However, the posterolateral choroidal artery infarctions are believed to be rare due to usual dominance of the anterior choroidal artery. Presently, with the use of MRI scanning, these areas can be easily visualized. Therefore, the posterolateral choroidal artery infarction can be diagnosed more easily. It is conceivable that more cases will be accurately diagnosed using this tool.

Cerebral Angiography↗
PubMed1992

[A case report of a massive pulmonary tumor embolism occurring during surgery for renal cell carcinoma].

A 59-year-old man, who suffered a massive pulmonary tumor embolism during surgery for renal cell carcinoma with vena caval invasion, was treated by emergency pulmonary embolectomy using cardiopulmonary bypass. Renal cell carcinoma occasionally extends into the inferior vena cava (IVC) as a tumor thrombus. In such patients, removal of the tumor thrombus from the IVC has to be performed in addition to radical nephrectomy. However, the massive pulmonary tumor embolism is a major potential hazard during radical surgical resection. To prevent intraoperative pulmonary embolisms from occurring, scheduled use of cardiopulmonary bypass with the cooperation of cardiovascular surgeons is recommended.

Carcinoma, Renal Cell↗
PubMed1992

[Hemiplegic migraine complicated with coronary vasospasm].

There are many theories and hypotheses concerning with the pathogenesis of migraine. The clinical effectiveness of vasoactive drugs and many investigations on the cerebral blood flow in patients with migraine strongly support a vascular theory. In present paper we report a case of 26-year-old Japanese male, who suffered from hemiplegic migraine and coincidental coronary vasospasm, and discussed the pathogenesis of migraine. In October 1986, the patient developed the first attack of throbbing headache in the left temporal area with nausea and vomiting, following typical visual aura. One week later, he developed the second migrainous attack and then he felt his right extremities paralyzed and numb. Although the headache and weakness resolved within one hour, similar migrainous attack with transient hemiparesis repeated two or three times a month. Although the longest period required for resolving weakness was three days, the MRI, the CT and the electroencephalogram revealed no significant abnormality. In January 1987, during his stereotyped attack of hemiplegic migraine, he also developed oppressive feeling on his anterior chest and these symptoms resolved within fifteen minutes. Because the results of Holter electrocardiogram and ultrasound echocardiogram indicated angina pectoris, a coronary angiography was performed in February 1987. During the angiographical procedures, he began to complain of the oppressive feeling on his anterior chest, and the coronary angiography revealed the definite vasospasm in the anterior descending branch of the left coronary artery. Sublingual nitroglycerin administration resolved the vasospasm, but thereafter the patient developed his stereotyped hemiplegic migrainous attack.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Secretion of chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase from cultured chick embryo chondrocytes.

We found that chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase were released into the culture medium from the cultured chick embryo chondrocytes. Since the release of the sulfotransferases was observed not only in serum-supplemented medium but also in serum-free medium, the released sulfotransferases were unlikely to be derived from serum. Addition of ascorbate to the serum-free medium supported the continuous release of the sulfotransferases. Monensin, which is known to cause dilatation of the Golgi apparatus and to inhibit sulfation of proteoglycan, was found to affect the release of the sulfotransferases. In the presence of 10(-6) M monensin, chondroitin 6-sulfotransferase activity in the cell layer was decreased to less than one tenth of the control, and the rate of the release of the activity became much smaller than the control after the initial rapid release. The activity of chondroitin 4-sulfotransferase was also affected by monensin, but the reduction of the chondroitin 4-sulfotransferase activity in the cell layer was not so great as the reduction of chondroitin 6-sulfotransferase activity. Unlike to the microsomal sulfotransferases, both chondroitin 6-sulfotransferase and chondroitin 4-sulfotransferase released into the culture medium were retained in the soluble fraction after centrifugation at 100,000 x g for 60 min, and were not activated by detergent. pH optimum and requirements for sulfhydryl compounds of the released sulfotransferases were similar to those observed previously in the chondroitin sulfotransferases from chick embryo cartilage and from cultured chick embryo chondrocytes. These results suggest that chondroitin sulfotransferases, which are localized in the Golgi apparatus, may be secreted to the extracellular space in a soluble form under the culture conditions.

Animals↗
PubMed1991

[Syntheses and antifungal activities of 1-[4-phenyl-2-(phenylthio or acyloxy)-n-butyl]-1H-imidazole derivatives].

The title compounds (4b, d-f, h-j) were prepared from 1-[4-(p-substituted phenyl)-2-chloro-n-butyl]-1H-imidazoles and the corresponding thiophenols or mercaptopyridines. Acyloxy compounds (5a-e) were prepared from alcohol (2b) and the corresponding acyl chlorides. In the antifungal activity test, p-tolyl compounds (4e, f) showed as good activity as butoconazole (4c).

Drug Resistance, Microbial↗
PubMed1991

Spatial gaze stability under active high-frequency head oscillation after acoustic neuroma surgery.

Spatial gaze stability under active high-frequency head oscillations was investigated in 31 patients after acoustic neuroma surgery. Whereas gaze stability upon rotation to the intact side was excellent during the entire time course after surgery, rotation to the affected side produced marked gaze disturbance at frequencies higher than 1.0 Hz, and did not recover even several years after surgery. The maximal oscillation frequency decreased in the patient group. Oscillopsia, being found in 20% of the patients, showed little correlation with gain value or maximal oscillation frequency. Long-lasting disturbances of active head oscillation, gaze stability and perception after unilateral labyrinthine loss may indicate persistent asymmetry of spatial orientation during high-frequency head movements.

Adult↗
PubMed1991

[The motion sickness under reversing goggles (1st report)].

We observed locomotion and motion sickness in 10 normal adults wearing reversing goggles while moving outdoors. Horizontal reversal of the visual field produced moderate to severe ataxia and motion sickness in all subjects except one. There was marked variability in the sensitivity among different subjects. In contrast, vertical reversal produced no symptoms. Confusion of information relation to spatial orientation possibly caused both the motion sickness and abnormal locomotion. Horizontal reversal of visual information produces disorientation because visual information is equal in importance to that from the semicircular canals. In the case of vertical reversal of visual information, orientation may be assured by gravity. The present study suggests that motion sickness is a biological signal alerting the organism to loss of spatial orientation rather than a mere autonomic symptom produced by mismatched sensory information. It appears that motion sickness is accompanied by dysequilibrium and abnormality of locomotion.

Adult↗
PubMed1990

cAMP regulation of the expression of prespore-specific genes, SP96 and Dp87, in disaggregated slug cells of Dictyostelium discoideum.

By Northern transfer and in vitro transcription assays, we examined how cAMP controlled the expression of prespore genes, Dp87 and SP96, in disaggregated slug cells of Dictyostelium discoideum. The transcription of these genes was halted soon after disaggregation and the remaining mRNAs were completely lost within 2 h. Addition of cAMP to cells which had lost the mRNAs induced the transcription of these genes, and the mRNAs were re-accumulated after a lag period of 30 min. The cAMP signal was transduced through the cell surface receptor. Protein synthesis was not needed for the induction of the transcription but was required for the accumulation of the mRNAs. We conclude that prespore gene expression is controlled by cAMP in two different ways: direct induction of transcription of the genes, and stabilization of the transcribed mRNAs by a protein(s) synthesized after addition of cAMP.

Blotting, Northern↗
PubMed1990

Isolation and characterization of spore coat protein (sp96) gene of Dictyostelium discoideum.

A cDNA library was constructed from poly(A)+ RNA isolated from slug cells of Dictyostelium discoideum, using lambda gt11 phage, and screened with an antiserum specific for the spore coat protein sp96. A positive clone was obtained and the gene product was identified as sp96. The sp96 mRNA is 2.2 kb in size, and it starts to accumulate at the tipped aggregate stage only in prespore cells. Southern analysis using nuclear DNA established that the sp96 gene is unique. Two genomic clones containing the sp96 gene were isolated and the sequence of the gene established. The coding region contains a long open reading frame interrupted by a single intron.

Amino Acid Sequence↗