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Biomedical subjects

I Ihara

Publications and source records attributed to I Ihara.

At least 19 recordsLinked to original sources
PubMed2001

Clad polymer buffer rods for polymer process monitoring.

Clad polymer buffer rods consisting of a polyetheretherketone (PEEK) core and a cladding made of a heat resistance epoxy aluminum composite are presented. The core has a uniform diameter or a taper shape. Ultrasonic measurement results indicate that the ultrasonic signal strength and signal to noise ratio of these clad rods are better than those of the non-clad PEEK rods for both longitudinal and shear waves because of the improved ultrasonic wave guidance in the core. Comparisons of these rods with those made of polymide and high-density polyethylene are given. Applications of these buffer rods for ultrasonic monitoring of polymer extrusion at temperatures up to 200 degrees C and pressures up to 180 psi are demonstrated. The monitoring results also reveal that within certain operating temperature and pressure range, clad polymer buffer rods show advantages over clad steel buffer rods.

Benzophenones↗
PubMed2001

River and groundwater nitrogen contamination caused by livestock production.

Water quality of rivers in Japanese domestic dairy and pig raising regions, as well as the groundwater in these regions, was investigated. Regarding the method of disposing livestock excreta, interview results from the livestock production farmers and the results of water quality analysis were evaluated. It is concluded that the rivers and the groundwater were contaminated due to inappropriate disposal methods of the livestock excreta. The concentrations of ammonium nitrogen and nitrate nitrogen in the rivers and groundwater were high. The sludge from the bottom of the rivers was also investigated and bacteria which are characteristic of excreta of dairy cattle and pigs were detected. The above pollutants were, therefore, considered to be of livestock origin.

Animals↗
PubMed1998

Proteolytic processing of Alzheimer's disease associated proteins.

Amyloid beta-peptide (A beta), the major component of senile plaques, is generated by proteolytic processing from the beta-amyloid precursor protein (beta APP). Mutations within the beta APP gene cause early onset familial AD (FAD) by affecting A beta generation. Interestingly, the much more abundant mutations within the presenilin (PS) genes also result in the abnormal generation of a 42 residue A beta (A beta 42), thus clearly supporting a pivotal role of A beta for the pathology of AD. PS proteins are proteolytically processed into stable 30 kDa N-terminal fragments (NTF) and 20 kDa C-terminal fragments (CTF). Beside the conventional proteolytic pathway. PS proteins can also be cleaved further C-terminal by proteases of the caspase superfamily. PS proteins were localized within the endoplasmic reticulum (ER) and early Golgi, compartments which we have demonstrated to be involved in A beta 42 generation and intracellular accumulation. Using Caenorhabditis elegans as a simple animal model, we demonstrate that PS proteins are involved in NOTCH signaling FAD causing mutations interfere with the biological function of PS proteins in NOTCH signaling.

Alzheimer Disease↗
PubMed1994

Cloning and sequence analysis of the rat augmenter of liver regeneration (ALR) gene: expression of biologically active recombinant ALR and demonstration of tissue distribution.

A full-length cDNA clone encoding a purified augmenter of liver regeneration (ALR) factor prepared from the cytosol of weanling rat livers was isolated. The 1.2-kb cDNA included a 299-bp 5' untranslated region, a 375-bp coding region, and a 550-bp 3' untranslated region. It encoded a protein consisting of 125 amino acids. The molecular weight of ALR calculated from the cDNA was 15,081, which is consistent with the size estimated by SDS/PAGE under reducing conditions. The molecular weight of the purified native ALR estimated by SDS/PAGE under nonreducing conditions was approximately 30,000; thus ALR apparently has a homodimeric structure. The recombinant ALR produced by expression of the cDNA in COS cells was tested in vivo in the canine Eck fistula model and found to have potency equivalent to the purified native ALR. The 125-aa sequence deduced from the rat ALR cDNA shows 50% homology to the amino acid sequence of the gene for oxidative phosphorylation and vegetative growth in the yeast Saccharomyces cerevisiae.

Amino Acid Sequence↗
PubMed1993

Structural study of the N-linked oligosaccharides of hepatocyte growth factor by two-dimensional sugar mapping.

The structures of the N-linked oligosaccharides on recombinant human hepatocyte growth factor (rh-HGF) expressed by Chinese hamster ovary (CHO) cells were studied by two-dimensional sugar mapping. The oligosaccharides released from the glycopeptides by peptide: N-glycosidase F (PNGase F) treatment were tagged with 2-aminopyridine at the reducing ends. The alpha-chain was linked by biantennary, triantennary, and tetraantennary oligosaccharides, but the dominant oligosaccharides linking the beta-chain were biantennary (> 85%). There was no significant difference in oligosaccharide structures between the two glycosylation sites on each chain, that is, Asn263 and Asn371 on the alpha-chain, and Asn535 and Asn622 on the beta-chain. The linkage of sialic acid to the non-reducing terminal galactose was identified as NeuAc alpha(2-3) by 1H-NMR spectrometry. The structures of the N-linked oligosaccharides from rat HGF were also studied. Triantennary oligosaccharides were obtained from the alpha-chain and a biantennary oligosaccharide was obtained from the beta-chain. This result indicates that the alpha-chain is also linked by higher branched oligosaccharides than the beta-chain in rat HGF.

Aminopyridines↗
PubMed1992

Hepatocyte growth factor is linked by O-glycosylated oligosaccharide on the alpha chain.

The glycosylation site and the structure of O-glycosylated oligosaccharide of recombinant human HGF were investigated. N-acetylgalactosamine (GalNAc) in the alpha chain suggested the presence of O-glycosylated oligosaccharide. Sugar analysis and amino acid sequence analysis of peptide fragments produced by limited degradation revealed that O-glycosylated oligosaccharide linked to Thr445 of the alpha chain. The molecular weight of the oligosaccharide was determined with ion spray mass spectrometry. From these studies, the structure of the O-glycosylated oligosaccharide on the alpha chain of HGF was concluded as [formula: see text].

Amino Acid Sequence↗
PubMed1991

Purification and characterization of hepatocyte growth factor from injured liver of carbon tetrachloride-treated rats.

A hepatocyte growth factor (HGF)-like substance that strongly stimulated DNA synthesis of adult rat hepatocytes in primary culture was found to increase markedly in liver of rats treated with carbon tetrachloride (CCl4). This increase of HGF-like activity was time- and dose-dependent, and 36 h after a dose of CCl4 of 0.2 ml per 100 g body weight the activity was about 20-times the normal level. The extent of induction of HGF-like factor correlated well with the extent of liver damage. The HGF-like factor was purified to homogeneity from the liver of CCl4-treated rats by a four-step procedure. The purified HGF-like factor had a molecular weight of 82-85 kDa, as estimated by SDS-PAGE, and was a heterodimer composed of a large subunit of about 69 kDa and a small subunit of 34 kDa linked by disulfide bridges. This factor had similar biological and chemical properties to HGF purified from rat platelets. Moreover, the N-terminal amino acid sequence of its 34-kDa subunit was identical to that of the small subunit of rat HGF. These findings indicate that the HGF-like factor in damaged liver of CCl4-treated rats is HGF and that liver itself can produce HGF when injured.

Amino Acid Sequence↗
PubMed1990

Isolation and expression of cDNA for different forms of hepatocyte growth factor from human leukocyte.

Human leukocyte cDNA library was screened to isolate cDNA clones coding for hepatocyte growth factor using cDNA from human liver as a probe. Nucleotide and deduced amino acid sequences were analyzed for two of four clones obtained. One of them contained an open reading frame coding for a polypeptide chain of 728 amino acid residues like that of cDNA clone derived from human liver. In another clone a spontaneous deletion of 15 base pairs was found within the coding sequence. When expressed transiently using COS-1 cells both clones produced protein with similar biological activity against rat hepatocyte in vitro.

Amino Acid Sequence↗
PubMed1990

Cerebellar hemorrhage after supratentorial craniotomy--report of three cases.

We report on three cases of remote cerebellar hemorrhage after supratentorial craniotomy, which had much in common in their computed tomographic, operative, and clinical findings. We speculate that, when the patient is in the supine position, displacement of the cerebellum causes stretching of the superior vermian veins and their tributaries, resulting in tearing of these vessels. Postoperative cerebrospinal fluid overdrainage or massive air reflux into the cranial cavity through the drainage tube may accelerate this process. Meticulous management of the drainage system is necessary to prevent this postoperative complication.

Adult↗
PubMed1990

Intra-abdominal cyst following revision of ventriculoperitoneal shunt--case report.

An intra-abdominal cyst is a rare complication of ventriculoperitoneal (VP) shunt. A 19-year-old male was admitted complaining of abdominal pain and distension, dysuria, constipation, headache, and fever. He had undergone a VP shunt for obstructive hydrocephalus caused by a cerebellar astrocytoma 16 years earlier, and had received shunt revision twice, 5 years and 3 months earlier, respectively. Examination on admission revealed neck stiffness, early papilledema, a mass in the lower abdomen, and abdominal muscular guarding with rebound tenderness. Laboratory studies showed leukocytosis of the peripheral blood and pleocytosis of the cerebrospinal fluid (CSF). Abdominal ultrasonograms and computed tomographic scans demonstrated a cystic lesion. Under the diagnosis of meningitis and local peritonitis with an intra-abdominal cyst, we sistemically administered antibiotics and externalized the shunt. However, since the cyst fluid could not be aspirated through the abdominal catheter, it was exchanged with a flexible catheter under fluoroscopic control, according to Seldinger's method. A total of 400 ml of cyst fluid was drained. Staphylococcus epidermidis was detected in both the cyst fluid and the CSF. After meningitis subsided, repositioning of the abdominal catheter into the other side of the abdomen was performed but resulted in shunt malfunction and meningitis due to the same organisms. After meningitis again subsided, the VP shunt was converted to a ventriculoatrial shunt. The clinical course was uneventful thereafter.

Abdomen↗
PubMed1988

The 28k and 70k dalton polypeptide components of mouse Ra-reactive factor are responsible for bactericidal activity.

Ra-reactive factor is a complement-dependent bactericidal factor that reacts specifically with Ra chemotype strains of Salmonella, and is ubiquitous in sera of a wide variety of vertebrates. Here we prepared an antiserum by immunizing rabbit with mouse Ra-reactive factor. This serum neutralized markedly the bactericidal activity of the factor. This action of the antiserum was inhibited by the factor whose bactericidal activity has been inactivated by heating for 30 min at 55 degrees C. Component polypeptides with apparent molecular weights of 28k and 70k in the factor were separated by SDS-polyacrylamide gel electrophoresis. They were also found to inhibit the antiserum activity. This indicates that these polypeptides carry the active site of the factor.

Animals↗