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Biomedical subjects

K Takeda

Publications and source records attributed to K Takeda.

At least 1,567 records · Page 87Linked to original sources
PubMedDate not supplied

Effects of pH in the in vitro chromosomal aberration test.

The relation between the pH of the medium and clastogenic activity was studied in Chinese hamster ovary (CHO) K1 cells in vitro. The pH was adjusted with NaOH, KOH, HCl or H2SO4. No clastogenic activity was observed over the initial pH range of 7.3-10.9 without S9 mix, but a few chromosomal aberrations were induced at pH 10.4 with S9 mix. The frequency of aberrations increased with the increase in amount of S9. At acidic pH, many chromatid breaks were induced at initiatial pH 5.5 or below without S9 mix, and aberrations such as chromatid breaks and chromatid exchanges were induced at initial pH 6.2 or below with S9 mix. Using MES and Bis-Tris as buffers instead of sodium bicarbonate, we observed that aberrations of the chromatid break type were inducible at pH 6.2 or below. These results show that the combination of strong alkalinity and S9 is clastogenic to CHO-K1 cells, and also that weakly acidic media are genetically active. The results indicate that incubations at non-physiological pH might give false-positive responses.

Animals↗
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High-level expression and characterization of hepatitis B virus surface antigen in silkworm using a baculovirus vector.

The Bombyx mori nuclear polyhedrosis virus (BmNPV) in the silkworm was used successfully for mass production of biologically active foreign genes under the control of the polyhedrin promoter. This system was adapted for the production of large amounts of hepatitis B virus surface antigens (HBsAg). The DNA fragments coded for the middle protein, which is composed of the S protein with the pre-S2 region, were cloned, the signal protein gene of beta-IFN was added, and both were inserted into a cloning vector. After co-transfection with wild-type BmNPV, stable recombinant viruses were isolated by the limiting dilution method. Infected silkworm larvae with the recombinants expressed HBsAg at high levels (400-600 micrograms/ml). These products, consisting of two polypeptides with molecular weights of approximately 25,000 (p25) and glycosylated P25 (GP28), were purified as assembled 22-nm particles. We demonstrated that HBsAg from silkworms consists of S protein with 7 amino acids of Pre-S2.

Amino Acid Sequence↗
PubMedDate not supplied

SEPs in two patients with localized lesions of the postcentral gyrus.

Scalp distributions of median nerve SEPs were studied in normal controls and 2 patients with localized lesions of the postcentral gyrus. In controls, parieto-occipital electrodes registered N20-P27 while frontal electrodes registered P20-N27. Other small components, parieto-occipital P22 and frontal N22, were recognized in about half of the control records. The wave forms at a frontal and a parieto-occipital electrode, both distant from the central region, formed exact mirror images of each other concerning N20-(P22)-P27 and P20-(N22)-N27. Electrodes near the central region contralateral to the stimulation registered cP22-cN30 (central P22 and central N30). When the postcentral gyrus was damaged, N20/P20-P27/N27 and cP22-cN30 were eliminated and the only remaining components were a frontal negative wave (frN) and a contralateral parieto-occipital positive wave (poP). Digital nerve stimulation also evoked poP and frN in both cases. In case 2, poP coincided with P22 of the non-affected side. The following generators were proposed; N20/P20-P27/N27: area 3b, cP22-cN30: areas 1 and 2, poP/early frN (= P22/N22): area 4 at the anterior wall of the central sulcus (due to direct thalamic inputs to motor cortex), late frN: uncertain (SMA?, SII?).

Adult↗
PubMedDate not supplied

Sex determination from plucked human hairs without epithelial root sheath. II. Depigmentation of melanin in the hair cortex before Feulgen reaction.

In hair roots devoid of the epithelial root sheath, an attempt was made to decolorize the melanin granules without affecting the Feulgen reaction for the sex chromatin. The hair samples were treated with 0.25% potassium permanganate for 1 hour, 0.3% hydrogen peroxide for 1 minute and 5% potassium permanganate for 1 hour, 0.3% hydrogen peroxide for 1 minute and 5% oxalic acid for 5 minutes, and then stained with Feulgen. The frequency of sex chromatins ranged from 22% to 47% (average 32%) in female samples and from 0% to 8% (average 5%) in male samples. Thus, the frequency distributions of the male and female samples were completely independent of each other. The sex chromatins in dried female hairs were detectable at a frequency of 16 - 26% several weeks after plucking. The depigmentation procedure almost completely bleached the melanin granules in the hair cortex, and produced no harmful effect on the Feulgen reaction that followed.

Adult↗
PubMedDate not supplied

Sex determination from plucked human hairs without epithelial root sheath. III. Fluorescent feulgen reaction using acriflavine.

In order to determine sex from plucked human hair roots devoid of epithelial root sheath, the frequency of the X-chromatin was examined in hair cortex nuclei of plucked hairs stained by the fluorescent Feulgen reaction using acriflavine. There was a distinct difference between male and female hairs, the frequency ranging from 27% to 70% (average 45.8%) in female samples and from 0% to 8% (average 2.9%) in male samples. The difference in the frequency between male and female was detected in samples kept in a dried condition for 32 weeks.

Acridines↗
PubMedDate not supplied

The effect of forskolin on the teratogenicity of methylxanthines in the chick embryo heart.

Interactions between forskolin and methylxanthines, including caffeine and isobutylmethylxanthine (IBMX), in the developing chick embryo heart were investigated. Forskolin, a potent activator of adenylate cyclase, was administered to young chick embryos (Hamburger-Hamilton stage 24) together with caffeine or IBMX at doses where each agent alone caused minimal embryotoxicity. The incidence of malformation in the embryonic chick heart or aorta induced by caffeine (5 x 10(-7) or 5 x 10(-6) mol) and IBMX (1 or 2.5 x 10(-6) mol) significantly increased with coadministration of forskolin (1 x 10(-9) mol). Cardiovascular malformations included ventricular septal defect, double outlet right ventricle, and aortic arch anomalies. These results indicate that forskolin potentiates the teratogenicity of caffeine or IBMX on the cardiovascular system in the chick embryo and suggest that this potentiation may be related to increase intracellular cAMP due to stimulation of adenylate cyclase (forskolin) and inhibition of phosphodiesterase (methylxanthines).

1-Methyl-3-isobutylxanthine↗
PubMedDate not supplied

Expression of bone morphogenetic protein genes in the human dental pulp cells.

Dental pulp has a potential to induce ectopic bone formation, but little is known about its mechanism. We thought that bone morphogenetic proteins (BMPs), members of the transforming growth factor-beta (TGF-beta) superfamily, are involved in the osteoinductive activity of dental pulp. In order to prove this assumption, we constructed a cDNA library from primary culture cells of human dental pulp (HDP cells), and screened the library with previously cloned cDNAs for mouse BMP-2 and -6 as probes. Three distinct cDNA clones encoding human BMP-2, -4 and -6 were isolated. By Northern blot analysis, specific transcripts of the genes of those BMPs were detected in the HDP cells. It was concluded that the BMPs were expressed in a certain population of dental pulp cells and might play some roles in ectopic bone formation by dental pulp.

Adolescent↗
PubMedDate not supplied

Fast 3D dynamic MR imaging of the liver with MR SmartPrep: comparison with helical CT in detecting hypervascular hepatocellular carcinoma.

Dynamic magnetic resonance (MR) imaging with SmartPrep was compared with dynamic enhanced helical computed tomography (CT) for the detection of hepatocellular carcinoma (HCC). Thirty patients with 49 HCCs were studied. Arterial-phase MR images using with SmartPrep were significantly superior to arterial-phase CT in detecting small lesions (< or = 2 cm) (85.3% vs. 67.6%, P < .05). In addition, in six recurrent tumors after arterial chemoembolization, dynamic MR imaging with MR SmartPrep technique was superior to helical CT in detecting of recurrent tumors.

Adult↗
PubMedDate not supplied

Treatment of acute aortic dissections with expandable metallic stents: experimental study.

PURPOSE: This experimental study was designed to evaluate the effectiveness of metallic stents for the treatment of acute aortic dissection. MATERIALS AND METHODS: Thoracic aortic dissections were created in 14 mongrel dogs. Aortography performed immediately after creation of dissections showed two types of aortic dissections: rapid flow in the false lumen (group 1) and slow flow in the false lumen (group 2). Each group consisted of seven dogs. For each group, expandable metallic Gianturco stents were placed in five dogs and two dogs were used as controls. RESULTS: A week later, false lumina were patent in all dogs in group 1 and thrombosed in all dogs in group 2. In group 1, the mean diameter of the true lumina was considerably enlarged from 5.9 mm +/- 1.6 to 9.9 mm +/- 2.8 and that of the false lumina significantly diminished from 9.1 mm +/- 1.3 to 5.2 mm +/- 2.3 (P < .05) after stent placement. In group 2, the true lumina were significantly dilated (5.2 mm +/- 2.3 vs 12.3 mm +/- 3.1, P < .05) and the false lumina disappeared completely (9.2 mm +/- 3.3 vs 0.0 mm, P < .01). Furthermore, the two control dogs in group 2 died of visceral ischemia due to the compression of the true lumen by the thrombosed false lumina, but the dogs with stents showed no symptoms of the visceral ischemia. CONCLUSION: Expandable metallic stents are not effective in obliterating the false lumen in acute aortic dissection but may be useful in maintaining the blood flow in the true lumen and avoiding visceral ischemia.

Aortic Dissection↗
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Treatment of aortic dissections with a percutaneous intravascular endoprosthesis: comparison of covered and bare stents.

PURPOSE: The authors developed a percutaneous endoprosthesis for treatment of aortic dissections. The device is a Gianturco stent wrapped with Dacron or nylon mesh. Effectiveness of the covered stent versus a bare stent was compared in the treatment of acute aortic dissection. MATERIALS AND METHODS: Experimental aortic dissections were created in 10 mongrel dogs. Occlusion of intimal tears was attempted with covered stents in five dogs (group 1) and with bare stents in the remaining five dogs (group 2). RESULTS: In group 1, entry tears were obliterated within 1 day (n = 3) or 1 week (n = 2) after stent placement and false lumina were thrombosed within 1 week (n = 3) or 1 month (n = 2). In group 2, entry tears and false lumina remained patent. Histologic specimens showed that the covered stents were entirely covered with smooth neointima. CONCLUSIONS: This endoprosthesis offers an alternative to surgical treatment for dissections of the descending aorta.

Acute Disease↗
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Superselective bronchial artery embolization for hemoptysis with a coaxial microcatheter system.

PURPOSE: To compare the effectiveness and safety of superselective bronchial artery embolization with that of nonsuperselective embolization in the control of hemoptysis. MATERIALS AND METHODS: Retrospective case analysis was done for 47 patients with hemoptysis originating from a variety of causes. In 22 patients, embolization was performed superselectively using a microcatheter inserted into the bronchial artery beyond the spinal or mediastinal branches (superselective group). In the remaining 25 patients, embolization was performed at the opening of the bronchial artery with a 5-F catheter (nonsuperselective group). RESULTS: Initial hemoptysis control rates were 96% (21 of 22) in the superselective group and 88% (22 of 25) in the nonsuperselective group. Cumulative hemoptysis control rates of the superselective and nonsuperselective groups were 80% and 67% at 6 months, 79% and 56% at 1 and 2 years, and 79% and 48% at 3 years, respectively (not significant; generalized Wilcoxon test). One major complication (spinal infarction) occurred in the nonsuperselective group. CONCLUSIONS: Superselective embolization is safer and more effective way to control hemoptysis than the ordinary (nonsuperselective) method.

Adult↗