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C Nojiri

Publications and source records attributed to C Nojiri.

At least 37 records · Page 2Linked to original sources
PubMed1992

Expression of a Maize Ubiquitin Gene Promoter-bar Chimeric Gene in Transgenic Rice Plants.

We have constructed a chimeric gene consisting of the promoter, first exon, and first intron of a maize ubiquitin gene (Ubi-1) and the coding sequence of the bar gene from Streptomyces hygroscopicus. This construct was transferred into rice (Oryza sativa L.) protoplasts via electroporation, and 10 plants were regenerated from calli that had been selected for resistance to exogenously supplied bialaphos. Transgenic plants grown in a greenhouse were resistant to both bialaphos and phosphinothricine at a dosage lethal to untransformed control plants. Evidence of stable integration of the transferred gene into the genome of the regenerated primary transformant plants was obtained from Southern blot analysis. In addition, northern blot analysis indicated expression and proper splicing of the maize ubiquitin gene first intron from the primary chimeric transcript in these transgenic rice plants, and western blot analysis and enzymic assays verified expression of the active bar gene product. Apparent mendelian segregation for bialaphos resistance in T(1) progeny of primary transformants was confirmed.

Journal Article↗
PubMed1992

Small soft left ventricular assist device powered by intraaortic balloon pump console for infants: a less expensive option.

We have developed a pneumatically driven 20 cc soft ventricle for temporary right, left, or biventricular assist. The ventricle consists of a vacuum-formed soft housing, diaphragm, tricuspid outflow valve, and biflap inflow valve. All components including inflow and outflow valves were made with Pellethane. The advantages of this blood pump are as follows: it eliminates use of the quick connect system and therefore is less thrombogenic; the biflap inflow valve provides low inflow resistance; the soft ventricle is easy to implant; the polyurethane valves eliminate blood damage and thromboembolism and are low in cost compared with mechanical valves; and the vacuum-forming technique is reliable, fast, capable of mass production, and therefore inexpensive. We have already demonstrated in both in vitro and in vivo experiments that this ventricle has excellent hemodynamic performance with less blood damage and thrombogenesis. In this study, we evaluated the possible application of a well-defined and widely distributed intraaortic balloon pump (IABP) console to the 20 cc left ventricular assist device (LVAD) driver. The pump was tested in 6 mongrel dogs (6 to 10 kg) using an IABP console. The pump was connected between the left atrium and the ascending aorta, placed paracorporeally on the chest wall, and driven at a synchronous or fixed rate mode without using vacuum. The 20 cc ventricle could maintain the same output as the control output of the natural heart at filling pressures of 5 to 10 mm Hg during the entire observation time of 5 h. Thus, this 20 cc soft ventricle has the potential to be widely used for the treatment of severe heart failure in infants because of its excellent hemodynamic performance, simplicity, and low cost.

Animals↗
PubMed1992

In vivo protein adsorption on polymers: visualization of adsorbed proteins on vascular implants in dogs.

The absorption of plasma proteins is an important event at the blood-material interface, and strongly affects subsequent cellular interaction and thrombus formation. Although considerable efforts have been expended to elucidate the mechanism of protein adsorption and the role of absorbed protein layer at the blood-material interface, there has been little knowledge of how the initial adsorbed proteins are maintained or changed in a time-variant process in in vivo long-term implantation. In this study, we described detailed analyses concerning the characterization of adsorbed proteins on HEMA--styrene block copolymer surfaces (HEMA-st) and poly(ethylene oxide) (PEO) grafted Biomer (B-PEO4K) for in vivo long-term canine vascular graft implants as well as in vitro short-term experiments. Biomer vascular grafts (6 mm I.D., 7 cm in length) were fabricated by a dip coating and the luminal surface was modified with PEO grafting, HEMA-st coating, or Biomer coating (control). These surface modified grafts were recirculated for different time intervals (5, 15, 30, 60 and 120 min) using citrated canine whole blood. The grafts were then implanted in the abdominal aortas of dogs and evaluated for graft patency and protein adsorption. The adsorbed proteins (albumin, IgG and fibrinogen) were quantified using an in situ radioimmunoassay. Surface protein layer thickness was measured by transmission electron microscopy (TEM). Visualization of absorbed plasma proteins (albumin, IgG and fibrinogen) was performed with TEM using an immunoperoxidase double antibody technique. In in vitro recirculation systems, albumin and IgG showed similar Langmuir type pattern onto all test surfaces. On B-PEO4K surfaces, fibrinogen adsorption kinetics demonstrated 'Vroman effect'. The Biomer and B-PEO4K grafts occluded within 1 month, while HEMA-st grafts were patent for over 3 months. Biomer and B-PEO4K showed thick multilayers of adsorbed proteins, and the thickness increased with implantation periods and the composition altered with time. In contrast, HEMA-st showed a monolayer-like adsorbed protein pattern, and the composition and thickness were consistent regardless of implantation time including in vitro short-time experiments, which may attribute to less conformational change of adsorbed proteins on HEMA-st surfaces. In terms of nonthrombogenicity, the stable monolayer-like adsorbed protein layer on HEMA-st surfaces exhibited improved blood compatibility over thick multilayered adsorbed proteins on Biomer and B-PEO4K surfaces.

Adsorption↗
PubMed1990

Blood compatibility of PEO grafted polyurethane and HEMA/styrene block copolymer surfaces.

HEMA/styrene (HEMA/STY) block copolymers and poly(ethylene oxide) 4,000 M.W. (PEO4K) grafted Biomer (B-PEO4K) surfaces have been synthesized, characterized, and evaluated as blood-contacting materials. These surfaces have demonstrated improved blood compatibility, compared to Biomer, in in vitro and ex vivo experiments. Biomer vascular grafts (6 mm I.D. 7 cm in length) were fabricated by a dip coating process. The luminal surface was modified either with PEO grafting, HEMA/STY coating, or Biomer coating (control). These surface-modified grafts were implanted in the abdominal aortas of dogs and evaluated for graft patency and protein adsorption. Surface protein layer thickness was measured by transmission electron microscopy (TEM). B-PEO4K and Biomer showed thick multilayers of adsorbed proteins (1000-2000 A) after 3 weeks to 1 month implantation. In contrast, HEMA/STY only showed a monolayer protein thickness (less than 200 A), even after 3 months. Visualization of adsorbed plasma proteins (albumin, IgG, and fibrinogen) was performed with scanning electron microscopy (SEM)/TEM using an immunogold double antibody technique. The pattern of protein distribution showed high concentrations of fibrinogen and IgG, and less albumin adsorbed onto Biomer and B-PEO4K. In contrast, HEMA/STY showed a patchy protein distribution pattern with high concentrations of albumin and IgG, and relatively less fibrinogen. Adsorbed monolayer patterns showed improved compatibility over multilayered proteins. The Biomer and B-PEO4K grafts occluded within 1 month, while HEMA/STY grafts were patent for over 3 months. The thin and stable adsorbed protein layer on HEMA/STY surfaces may be associated with the microdomain structures of the surface, and will play an important role in long-term in vivo blood compatibility. This manuscript will evaluate the long-term in vivo performance of these polymers, analyze the extent of protein adsorption onto the surfaces, and correlate protein layer thickness to the thrombogenicity of the polymer surfaces.

Adsorption↗
PubMed1990

Synthesis and characterization of poly(dimethylsiloxane)-poly(ethylene oxide)-heparin CBABC type block copolymers.

Heparin and poly(ethylene oxide) were coupled to a central anchoring block of poly(dimethylsiloxane) in order to investigate its blood compatible properties. Diamino telechelic poly(dimethylsiloxane) (PDMS-(NH2)2, Mw = 20,000) was first modified to isocyanate functionalities using toluene 2,4-diisocyanate. This modified PDMS was then coupled to diamino-telechelic poly(ethylene oxide) (PEO-(NH2)2, Mw = 2000, 4000, 6000) to create BAB type copolymers having terminal free amino groups. These amino groups were covalently coupled to heparin containing terminal aldehyde groups using sodium cyanoborohydride to yield a bioactive, CBABC type block copolymer. The physical characterization of these copolymers was performed with IR, NMR, sulphur elemental analysis, Wilhelmy plate contact angle, and differential scanning calorimetry (DSC). CBABC block copolymer surfaces demonstrated heparin bioactivity in in vitro evaluation, and improved nonthrombogenic properties during ex vivo A-A shunt experiments.

Animals↗
PubMed1989

In vitro and ex vivo platelet interactions with hydrophilic-hydrophobic poly(ethylene oxide)-polystyrene multiblock copolymers.

Hydrophilic-hydrophobic multiblock copolymers synthesized from telechelic oligomers of poly(ethylene oxide) (PEO) and polystyrene (PS) have been used to study the influence of hydrophilic and hydrophobic balance on interfacial interactions of these surfaces with blood components. In vitro coagulation assays show no inherent ability of these amphiphilic surfaces to affect contact activation or coagulation factors. In vitro platelet adhesion and release reactions from rabbit platelet-rich plasma were shown to be greatest on Biomer and PS homopolymer surfaces and least on cross-linked PEO surfaces, with the PEO-PS block copolymers demonstrating intermediate responses. These same substrates were tested in a new low-flow, low-shear arterio-artery shunt system in rabbits. Whole blood occlusion times were not a direct function of hydrophilic content as both PEO and PS homopolymers and Biomer showed short occlusion times, while PEO-PS block copolymers prolonged occlusion times considerably, depending on composition. Overall, results suggest that PEO-PS block copolymers promote unique whole blood responses in contrast to homopolymer and Biomer controls which are more complex than direct correlations to bulk hydrophilic and hydrophobic contents.

Anastomosis, Surgical↗
PubMed1988

Nucleotide sequence of the ribostamycin phosphotransferase gene and of its control region in Streptomyces ribosidificus.

The nucleotide sequence of an aminoglycoside phosphotransferase gene (rph) from Streptomyces ribosidificus (a ribostamycin producer) was determined. Molecular size, amino acid composition and N-terminal amino acid sequence of the purified rph product confirmed the position of the coding region deduced from the nucleotide sequence. The 5' region of rph has been tested for its transcriptional controls; high-resolution mung-bean nuclease mapping of in vivo transcripts revealed one major start point, rphS1, controlled by the rphP1 promoter. This transcript was also observed in vitro in run-off experiments using purified Streptomyces RNA polymerase. This transcriptional start point coincided with the translational start site, with the mRNA 5' terminus being pppATG. The results of promoter-probing tests and insertion of a transcriptional termination fragment into the rph promoter region have shown that the rphP1 transcript was sufficient and essential for rph expression.

Amino Acid Sequence↗
PubMed1988

Heparin immobilization onto segmented polyurethane-urea surfaces--effect of hydrophilic spacers.

Heparin was immobilized onto segmented polyurethane-urea surfaces (Biomer) using hydrophilic poly(ethylene oxide) spacers of different chain lengths. The use of the hydrophilic spacer, poly(ethylene oxide), reduces protein adsorption and subsequent platelet adhesion on the surface. In addition, the bioactivity of the immobilized heparin is enhanced by the incorporation of these spacers. Immobilized heparin bioactivity is shown to be a function of PEO spacer length. Use of hydrophilic PEO spacers demonstrates that immobilized heparin's bioactivity is consistently higher than that of the C6 alkyl spacer, but heparin-immobilized surfaces demonstrate no chain length effect on platelet adhesion, even though they show less platelet adhesion compared to Biomer controls. In the case of PEO-grafted surfaces, platelet adhesion is decreased compared to Biomer controls, and C6 alkyl spacer-grafted surfaces, and exhibits a minimum at PEO 1000. In ex vivo A-A shunt experiments under low flow and low shear conditions, all heparinized surfaces exhibit significant prolongation of occlusion times compared to Biomer controls, indicating an ability of immobilized heparin to inhibit thrombosis in whole blood.

Animals↗
PubMed1987

Molecular cloning and characterization of the Streptomyces hygroscopicus alpha-amylase gene.

We have isolated and sequenced a gene (amy) coding for alpha-amylase (EC 3.2.1.1.) from the Streptomyces hygroscopicus genome (H. Hidaka, Y. Koaze, K. Yoshida, T. Niwa, T. Shomura, and T. Niida, Die Stärke 26:413-416, 1974). Amylase was purified to obtain amino acid sequence information which was used to synthesize oligonucleotide probes. amy-containing Escherichia coli cosmids identified by hybridization did not express amylase activity. Subcloning experiments indicated that amy could be expressed from the lac promoter in E. coli or from its own promoter in S. lividans. The amy nucleotide sequence indicated that it coded for a protein of 52 kilodaltons (478 amino acids). Secreted alpha-amylase contained amino- and carboxy-terminal as well as internal amino acid sequences which were consistent with the nucleotide sequence. The 30-residue leader sequence showed similarities to those found in other procaryotes. The DNA sequence 5' to the amy structural gene contained a sequence complementary to the 3'-terminal sequence of 16S rRNA of S. lividans (M. J. Bibb and S. N. Cohen, Mol. Gen. Genet. 187:265-277, 1982). The transcriptional start points of amy were determined by mung bean nuclease mapping, but the promoter of amy was not similar to the consensus sequence found in other procaryotes.

Amino Acid Sequence↗
PubMed1987

Aorta-coronary bypass grafting with heparinized vascular grafts in dogs. A preliminary study.

At present, only the autogenous saphenous vein is acceptable in aorta-coronary bypass grafting. We developed a small-caliber vascular graft and evaluated the potential application for aorta-coronary bypass grafting. Canine carotid arteries were cross-linked with polyepoxy compounds, such as polyglycerol polyglycidyl ether, which is a new cross-linking reagent, and then heparinized by our own method. The polyepoxy compound-cross-linked graft can keep the natural vessel compliance and is stronger than the glutaraldehyde-cross-linked graft; thus, it provides excellent suturability and compliance match. Heparin was gradually released from the graft wall, and thrombus formation was completely prevented during the period before development of the endothelial lining. As a pilot study, the grafts, 2 to 3 mm in internal diameter and 5 to 7 cm in length, were evaluated as bilateral carotid replacements in five dogs. All grafts were patent at intervals of 14 to 177 days. Histologic examinations showed excellent antithrombogenic and healing characteristics, although the endothelialization was delayed by heparin, which inhibits cell adhesion and fibrin deposition. The 3 mm internal diameter graft was evaluated as an aorta-coronary bypass grafting model in eight dogs. Flow within grafts to the right coronary artery ranged from 25 to 35 ml/min, and flow in the circumflex or left anterior descending grafts ranged from 75 to 100 ml/min. Cineangiography was performed to confirm graft patency. Three dogs died of viral infection and one was killed. At necropsy, the grafts remained patent without thrombi along the graft length. Four dogs were allowed to survive for long-term evaluation. All grafts were patent at time intervals to 21 to 113 days with 100% patency. These results led us to conclude that our newly developed small-caliber vascular graft shows great promise in application for aorta-coronary bypass grafting.

Animals↗
PubMed1984

Conduction disturbance in Behçet's disease. Association with ruptured aneurysm of the sinus of valsalva into the left ventricular cavity.

Cardio-Behcet's disease is not often reported; only one case to our knowledge has described complete atrioventricular (AV) block, without pathologic details. We document, from direct observation during surgery and pathologic examination of associated lesions, a case whose conduction disturbance was possibly caused by direct extension of Behcet's disease itself into the conduction system.

Aortic Rupture↗