Biomedical subjects

T Ikoma

Publications and source records attributed to T Ikoma.

At least 19 recordsLinked to original sources

PubMed2002

The cross-linkage effect of hydroxyapatite/collagen nanocomposites on a self-organization phenomenon.

Hydroxyapatite(HAp)/collagen nanocomposites were prepared by a coprecipitation method controlling the degree of cross-linkage between collagen molecules using glutaraldehyde. The precipitates filtered were dried in a freeze drier or naturally dried in the air at 25 degrees C. The naturally dried cakes had open channels of 5-15 microm in diameters, which were three-dimensionally and regularly developed over the whole samples, and showed a pretty good mechanical strength. The channels that were formed at spaces among the HAp/collagen particles, cross-linked one another, which had been filled up with water before its evaporation. The ordering state of the open channels depended on the degree of cross-linkage with glutaraldehyde; the optimal self-organized state was found when 30 molecules of glutaraldehyde were added per collagen molecule, though an excess amount of glutaraldehyde suppressed the appearance of the ordered state. From SEM and FT-IR measurements, it was indicated that the self-organization in the HAp/collagen nanocompsites continuously occurred during the drying process together with the removal of water and the increase of the density.

Journal Article↗

PubMed2001

Effects of quartz addition on the mechanochemical dechlorination of chlorobiphenyl by using CaO.

Grinding a mixture of 3-chlorobiphenyl (BP-Cl) and CaO with or without the addition of quartz was conducted in air by a planetary ball mill to investigate the mechanochemical dechlorination of BP-Cl. The dechlorinating reaction proceeds with an increase in grinding time, and over 99% of BP-Cl is decomposed at 360 min. Washing the ground sample with different solvents results in different products. Addition of quartz to the grinding mixture facilitates dechlorination efficiency, especially in the case of a high weight ratio of BP-Cl to CaO.

Biomechanical Phenomena↗

PubMed2001

Experimental and theoretical studies on ferromagnetically coupled metal complexes with imino nitroxides.

Copper(II), zinc(II), and nickel(II) complexes with tridentate imino nitroxyl diradicals, [CuCl(bisimpy)(MeOH)](PF(6)) (1), [ZnCl(2)(bisimpy)] (2), and [NiCl(bisimpy)(H(2)O)(2)]Cl x 2H(2)O (3) (bisimpy = 2,6-bis(1'-oxyl-4',4',5',5'-tetramethyl-4',5'-dihydro-1'H-imidazol-2'-yl)pyridine), were prepared, and their magnetic properties were studied. In 1, the Cu(II) ion has a square pyramidal coordination geometry, of which the equatorial coordination sites are occupied by three nitrogen atoms from the bisimpy and a chloride ion. The coordination geometry of the Zn(II) ion in 2 can be described as a trigonal bipyramid, with two chloride ions and a bisimpy. In 3, the Ni(II) ion has a distorted octahedral coordination geometry, of which four coordination sites are coordinated by the bisimpy and chloride ion, and two water molecules occupy the remaining cis positions. Magnetic susceptibility and EPR measurements revealed that in 1 and 3 the Cu(II) and Ni(II) ions with imino nitroxyl diradicals were ferromagnetically coupled, with the coupling constants J (H = -2J(ij) summation operator S(i)S(j)) of +165(1) and 109(2) cm(-1), respectively, and the intraligand ferromagnetic interactions in 1-3 were very weak. DFT molecular orbital calculations were performed on the diradical ligand, 1, and 2 to study the spin density distribution before and after coordination to the metal ions.

Journal Article↗

PubMed2001

Modulation of the expression of the Cip/Kip family of cyclin-dependent kinase inhibitors in foetal developing lungs of hamsters.

We examine the cell proliferation activity and expression of cyclin-dependent kinase inhibitors of the Cip/Kip family, p21Cip1, p27Kip1 and p57Kip2, in foetal hamster lungs to determine the expression patterns of the cyclin-dependent kinase inhibitors and to clarify the relationship between expression of the cyclin-dependent kinase inhibitors and lung development. Foetal hamster lungs on gestational days 12.5-16 (the day of birth) and adult lungs were fixed in 4% paraformaldehyde. Frozen sections were immunostained for the cyclin-dependent kinase inhibitors, and examined by immunostaining for Ki-67 and bromodeoxyuridine to determine the proliferation activity of the foetal lungs. During the foetal period, cell proliferation activity, as analysed by Ki-67 or bromodeoxyuridine labelling, decreased with development of the lung. In contrast to the gradual decrease of cell proliferation activity, cells with p27Kip1 immunoreactivity increased with development. On the other hand, p21Cip1-positive cells were most prominent around gestational day 14.5, while after birth positive cells decreased markedly. A few p57Kip2-positive cells were detected in the bronchiolar epithelium on gestational day 14.5. Western blotting analyses confirmed these immunostaining patterns. Thus, the levels of the cyclin-dependent kinase inhibitors of the Cip/Kip family are modulated in the lungs during the foetal period, and each shows a unique expression pattern. The cyclin-dependent kinase inhibitors may play roles not only in regulating cell proliferation activity but also in regulating other functions such as differentiation in the lung during the foetal period.

Aging↗

PubMed2001

Anti-tumor effect of gallic acid on LL-2 lung cancer cells transplanted in mice.

We previously reported that gallic acid (3,4,5-trihydroxybenzoic acid), a naturally occurring plant phenol, can induce apoptosis in four kinds of human lung cancer cell lines in vitro. The present study further investigated the in vivo anti-tumor effects of orally administered gallic acid. Gallic acid reduced cell viability of LL-2 mouse lung cancer cells in vitro dose dependently, with a 50% inhibitory concentration (IC50) value of around 200 microM. C57Black mice were transplanted with LL-2 cells, and administered gallic acid (1 mg/ml in drinking water, ad libitum) and/or cisplatin (4 mg/kg i.p. injection, once a week). The average weight of the transplanted tumors, obtained at 29 days after transplantation, in the mice of control, gallic acid-treated cisplatin-treated and cisplatin plus gallic acid-treated groups was 4.02, 3.65, 3.19 and 1.72 g, respectively. The average tumor weight of the mice treated with cisplatin combined with gallic acid was significantly smaller than that of the control group (p<0.05). The amount of apoptotic cells in the tumor tissues of mice treated with gallic acid and/or cisplatin was significantly higher than those of the control mice. Combination of gallic acid and cisplatin increased the tumor cell apoptosis compared with the treatment with cisplatin alone. The present findings suggest that the combination of gallic acid with an anti-cancer drug, including cisplatin, may be an effective protocol for lung cancer therapy.

Animals↗

PubMed2000

[mRNA detection of beta-myosin heavy chain gene in the autopsy cases of hypertrophic cardiomyopathy].

A known trigger of sudden cardiac death, hypertrophic cardiomyopathy (HCM) is associated with a point mutation in or overexpression of MYH7, which encodes the sarcomere protein beta-myosin heavy chain. We used nested RT-PCR to detect MYH7 mRNA in left ventricular myocardial tissue. We extracted total RNA from tissue samples that had been obtained after autopsy of 8 people who had died from HCM-related sudden death and that had been fixed in 10% formalin solution for as long as 4 years. The abundance of total RNA extracted from the 100 mg samples of cardiac muscle ranged from 10 to 24 mg/ml. The products of the nested RT-PCR were electrophoresed on a denaturing 8% polyacrylamide gel, and the MYH7 mRNA product was detected as a 424 bp band. MYH7 mRNA was easier to detect in tissue that had been fixed for shorter rather than longer periods. In addition, the greater the cardiac weight, the higher was the yield of the MYH7 mRNA product. Although mRNA had been detected by using RT-PCR on formalin-fixed paraffin-embedded tissue, no one previously had identified by using RT-PCR or nested RT-PCR on formalin-fixed tissue. By using nested RT-PCR, we were able to detect MYH7 mRNA in myocardial tissue that had been fixed in formalin solution for 4 years. Our results are applicable to retrospective examination into the cause of death in cases of sudden cardiac failure.

Adult↗

PubMed1999

Inactivation of proprotein convertase, PACE4, by alpha1-antitrypsin Portland (alpha1-PDX), a blocker of proteolytic activation of bone morphogenetic protein during embryogenesis: evidence that PACE4 is able to form an SDS-stable acyl intermediate with alpha1-PDX.

PACE4 (SPC4), a member of the subtilisin-like proprotein convertase (SPC) family of proteases that cleave at paired basic amino acids, exhibits a dynamic expression pattern during embryogenesis and colocalizes with bone morphogenetic proteins (BMPs). Recently Cui et al. reported that the ectopic expression of alpha1-antitrypsin variant Portland (alpha1-PDX), an engineered serpin that contains the minimal SPC consensus motif in its reactive loop, blocks the proteolytic activation of BMP4, leading to abnormal embryogenic development [Cui, Y. et al. (1998) EMBO J. 17, 4735-4743]. TGFbeta-related factors such as BMPs are synthesized as inactive precursors and activated by limited proteolysis at multibasic amino acids. Therefore, an alpha1-PDX-inhibitable protease is thought to participate in BMP activation. However, conflicting properties, including sensitivity to alpha1-PDX, have been reported for PACE4. In this study, we examined whether alpha1-PDX is responsible for the inhibition of PACE4 by measuring the protease/inhibitor complex directly. Here we show that alpha1-PDX has the ability to form an SDS-stable acyl-intermediate (180 kDa) with PACE4 in vivo and in vitro. Further, we characterized the PACE4 secreted into the culture medium from Cos-1 cells by a specific immunological assay. An alpha1-PDX-insensitive and decanoyl-RVKR-chloromethylketone-sensitive 60-kDa protease(s) is greatly activated in conditioned medium by PACE4 overexpression, suggesting that the activation of an unknown protease(s) other than PACE4 is the cause of the variation in the properties of PACE4. PACE4 is a Ca(2+)-dependent protease with an optimal Ca(2+) requirement of 2 mM, and shows its highest activity at weakly basic pH. PACE4 activity is completely inhibited by EDTA and EGTA, but not by leupeptin. These results show that PACE4 activity can be inhibited by alpha1-PDX as well as furin (SPC1) and suggest that the inhibition of PACE4-mediated activation of factors such as BMPs by alpha1-PDX causes abnormal embryogenic development.

Animals↗

PubMed1999

[Intratumoral ethanol injection therapy using endoscopic video information system].

Bronchoscopic ethanol injection (BEI) therapy for endobronchial malignant tumor is thought to be an effective modality for airway dilatation and hemostasis without expensive special equipment. But if ethanol leaks into the airway, it causes severe coughing and erosion of bronchial wall. Using endoscopic video information system (EVIS), an assistant operator can observe an ethanol leak and inject an adequate volume. To evaluate the efficacy and adverse effect of BEI therapy, we treated 8 patients with endobronchial malignant tumor using EVIS. Under local anesthesia, a video-bronchoscope (Olympus BF200 or BF 1T200) was inserted orally, a transbronchial aspiration cytology (TBAC) needle was inserted via the biopsy channel, and injections of 0.2 ml of 99% ethanol into the tumor were repeated. After the tumor degenerated to necrotic tissue, it was removed with a biopsy forceps, and this maneuver was repeated for the existing fresh lesion. The total volume of injected ethanol was 4.5 + 1.6 ml (mean + SD). Airway obstruction and atelectasis were relieved in 4 cases, and hemostasis was obtained in 2 cases. In 2 cases, airway dilatation and hemostasis were not obtained. BEI was more effective in the patients with polypoid or nodular tumor protruding into the airway lumen. As for adverse effects, ethanol leaks caused a severe cough in 2 cases, although they were tolerable and treatment could be continued. BEI therapy using EVIS was thought to be useful to control airway obstruction by endobronchial polypoid tumor with good cost-effectiveness and fewer adverse effects.

Bronchial Neoplasms↗

PubMed1996

A case of Crush syndrome with giant negative T waves and reversible left ventricular dysfunction.

A 54-year-old male experienced the Hanshin earthquake at 5:46 am on Jan. 17, 1995. He was rescued after being buried under his house for 20 h. After being treated at two hospitals, he was admitted to our hospital with acute renal failure caused by crush syndrome. The maximal serum creatinine kinase level was 35,000 IU/L (CK-MM: 100%), and the maximal myoglobin level was 12,600 ng/ml. An electrocardiogram showed inverted T waves in V5,6 which later became giant negative T waves, and a QS pattern in a VL and V1-6. Two-dimensional echocardiography showed a hypokinetic left ventricle. He was treated with hemodialysis 13 times. Cardiac contraction gradually improved to the normal level. Coronary angiography revealed normal coronary arteries and acetylcholine did not induce coronary spasm. Biopsy specimens from the right ventricular septum showed slight degeneration. 201Tl imaging showed hypoperfusion except in the anterior wall and 123I-MIBG imaging showed a perfusion defect except in the anterior wall. After about 1 month, only 201Tl imaging showed improvement. We believe that myocardial ischemia, cardiac sympathetic nerve damage and/or cardiac contusion caused giant negative T waves and left ventricular dysfunction. This is a rare case which showed significant myocardial damage with crush syndrome.

3-Iodobenzylguanidine↗

PubMed1996

[Bucillamin induced lung injury in rheumatoid arthritis].

Thirteen cases with rheumatoid arthritis who experienced lung injury during the treatment with bucillamine (Bc), about whom the questionnaires were answered by the physicians and whose X-ray films could be rechecked, were studied. Nine cases out of the 13 showed patchy mottled infiltrates in the bilateral center sparing the periphery, and the other 4 showed diffuse infiltrates. In these 9, serum gamma-globulin level decreased when lung injury appeared. The gamma-globulin level before the start of Bc administration, the level when lung injury appeared, the gamma-globulin decrease, and its ratio to the level before Bc were 1790 +/- 661 mg/dl, 1297 +/- 666 mg/dl, 459 +/- 320 mg/dl and 29.1 +/- 18.0%, respectively. In 5 out of the 9, gamma-globulin level reincreased when they recovered from the injury: 2 out of the 5 showed the reincrease even after steroid therapy. The data were obtained only from 2 out of the 4 with diffuse pattern in X-ray, and the decrease and the decrease ratio were 200 mg/dl (5.8%) in 1, and 49 mg/dl (3.6%) in the other. The characteristics of Bc-induced lung injury might be mottled infiltrates in the center appearing concurrently with serum immunoglobulin decrease.

Aged↗

PubMed1995

Follow-up observation of a patient with left ventricular thrombus by echocardiography.

We report a case of left ventricular thrombus which caused systemic embolism during warfarin therapy. A 66-year-old man admitted to our hospital with intermittent loss of consciousness and incomplete palsy. The patient had a past history of cerebral infarction, hypertension and diabetes mellitus. Electrocardiography showed abnormal Q waves at II, III, and aVF. Echocardiography showed a mobile protruding thrombus at the left ventricular apex. Left ventricular cineangiography showed a filling defect at the left ventricle. Coronary angiography confirmed total occlusion of the right coronary artery and significant stenosis of the left coronary artery. After administration of warfarin, the patient suddenly fell down to the comatose state. His left arm became pale without pulsation. The thrombus in the left ventricle disappeared by echocardiography and systemic embolism was suspected. Thromboembolectomy from his left arm was performed. Two weeks after the day brain computed tomography showed low density area at the posterior lobe of the cerebrum. Although the eyesight of the patient was lost, he could stand and walk with some help two months later. This is a rare case of systemic embolism during warfarin therapy due to left ventricular thrombus whose process was constantly observed by echocardiography.

Aged↗

PubMed1994