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Biomedical subjects

J Kobayashi

Publications and source records attributed to J Kobayashi.

At least 37 records · Page 2Linked to original sources
PubMed2001

Cloning and functional expression of a chitinase cDNA from the common cutworm, Spodoptera litura, using a recombinant baculovirus lacking the virus-encoded chitinase gene.

A Chitinase cDNA named Slchi was cloned from the epidermis of the common cutworm, Spodoptera litura, and the enzymatic properties of its recombinant proteins were characterized. The Slchi cDNA encodes 552 amino-acid residues (aa) including a 19 aa putative signal peptide, with the calculated molecular mass of the putative mature protein 60,152 Da. A major transcript of Slchi about 2.8 kb was detected in the epidermis only during molting in the last instar larvae, suggesting its involvement in the digestive system for old cuticle. The E. coli-produced recombinant Slchi exhibited weak chitinolytic activity against 4MU-(GlcNAc)(3)>4MU-(GlcNAc)(2)>4MU-(GlcNAc)(4), in this order, but not against 4MU-(GlcNAc)(1). A recombinant Slchi with higher specific activity was obtained using recombinant Hyphantria cunea NPV (HycuNPV), which expresses Slchi under polyhedrin promoter. To discriminate chitinase activity of recombinant Slchi from an active chitinase encoded in HycuNPV genome (chiA), we further knocked out the chiA gene from the recombinant virus. The recombinant Slchi expressed in insect cell culture showed a similar substrate specificity against 4MU-(GlcNAc)(n) (n=1-4) to that produced in E. coli, while the viral chitinase showed the highest activity against 4MU-(GlcNAc)(2). The recombinant Slchi was secreted rapidly into the culture medium from the infected cells, whereas the viral chitinase retained predominantly in the cells.

Amino Acid Sequence↗
PubMed2001

Acetylsalicylic acid reduces ischemia-induced proliferation of dentate cells in gerbils.

Transient global ischemia causes neurogenesis in the dentate gyrus of adult rodents. Ischemic insults to rodents also induce cyclooxygenase-2 (COX-2), an isoform of cyclooxygenases (COXs) and a rate-limiting enzyme for prostanoid synthesis. In the present experiments, adult Mongolian gerbils were chronically treated with acetylsalicylic acid (ASA), a non-selective COX inhibitor, and the proliferation of cells in the dentate gyrus was examined under ischemia. It was proved that BrdU-labeled cells in the dentate gyrus were significantly reduced in number following ASA treatment after 10 min global ischemia. The result strongly suggests that COX, probably COX-2, and prostanoids play an important role in the proliferation of neural cells after ischemia in gerbils.

Animals↗
PubMed2001

Miscoding potential of the N2-ethyl-2'-deoxyguanosine DNA adduct by the exonuclease-free Klenow fragment of Escherichia coli DNA polymerase I.

Acetaldehyde, a major metabolite of ethanol, reacts with dG residues in DNA, resulting in the formation of the N(2)-ethyl-2'-deoxyguanosine (N(2)-Et-dG) adduct. This adduct has been detected in lymphocyte DNA of alcohol abusers. To explore the miscoding property of the N(2)-Et-dG DNA adduct, phosphoramidite chemical synthesis was used to prepare site-specifically modified oligodeoxynucleotides containing a single N(2)-Et-dG. These N(2)-Et-dG-modified oligodeoxynucleotides were used as templates for primer extension reactions catalyzed by the 3' --> 5' exonuclease-free (exo(-)) Klenow fragment of Escherichia coli DNA polymerase I. The primer extension was retarded one base prior to the N(2)-Et-dG lesion and opposite the lesion; however, when the enzyme was incubated for a longer time or with increased amounts of this enzyme, full extension occurred. Quantitative analysis of the fully extended products showed the preferential incorporation of dGMP and dCMP opposite the N(2)-Et-dG lesion, accompanied by a small amounts of dAMP and dTMP incorporation and one- and two-base deletions. Steady-state kinetic studies were also performed to determine the frequency of nucleotide insertion opposite the N(2)-Et-dG lesion and chain extension from the 3' terminus from the dN.N(2)-Et-dG (N is C, A, G, or T) pairs. These results indicate that the N(2)-Et-dG DNA adduct may generate G --> C transversions in living cells. Such a mutational spectrum has not been detected with other methylated dG adducts, including 8-methyl-2'-deoxyguanosine, O(6)-methyl-2'-deoxyguanosine, and N(2)-methyl-2'-deoxyguanosine. In addition, N(2)-ethyl-2'-deoxyguanosine triphosphate (N(2)-Et-dGTP) was efficiently incorporated opposite a template dC during DNA synthesis catalyzed by the exo(-) Klenow fragment. The utilization of N(2)-Et-dGTP was also determined by steady-state kinetic studies. N(2)-Et-dG DNA adducts are also formed by the incorporation of N(2)-Et-dGTP into DNA and may cause mutations, leading to the development of alcohol- and acetaldehyde-induced human cancers.

DNA Adducts↗
PubMed2001

Effect of apolipoprotein E3/4 phenotype on postprandial triglycerides and retinyl palmitate metabolism in plasma from hyperlipidemic subjects in Japan.

In a previous study it was shown that postprandial lipid metabolism is delayed in individuals with intra-abdominal visceral fat accumulation. Population studies have shown that as compared with individuals with apolipoprotein (apo) E3/3, those with phenotype apo E3/4 phenotype have higher plasma and low density lipoprotein (LDL)-cholesterol (C) concentration and increased susceptibility to coronary heart disease. The aim of the present study is to determine how apo E4 affects postprandial lipid metabolism by comparing individuals with apo E3/4 to those with apo E3/3 phenotype matched for abdominal visceral fat. Sixty-two Japanese subjects (41 male, 21 female) [average age 48+/-14 years; mean body mass index (BMI) 25+/-5.6 kg/m2] were recruited for this study. The subjects were divided into two groups: those with apo E3/3 (n=43) and those with apo E3/4 phenotype (n=19), as determined by isoelectric focusing (IEF). Visceral fat accumulation was analyzed as area of fat deposition by computerized tomography at the umbilicus level. After a 12-h overnight fasting, an oral vitamin A and a fatty meal were administered to these subjects. The plasma triglyceride (TG) increased significantly hours after fat loading in both groups but the levels of TG were significantly higher in apo E3/4 than in apo E3/3 phenotype at 2, 4 and 6 h after fat loading. Plasma retinyl palmitate (RP) levels were also significantly higher in individuals with apo E3/4 than in those with apo E3/3 phenotype at 2, 4 and 6 h after fat loading. This investigation was then conducted in both genders separately, and found that these associations were statistically significant in men. Furthermore, after matching men for fasting TG levels, these associations did not persist for plasma TG levels at any time point, while plasma RP levels were still significantly higher in apo E3/4 group at 2 and 6 h after fat loading. These results indicate that in Japanese population especially for men apo E phenotype E3/4 is associated with an impaired postprandial TG-rich lipoprotein metabolism relative to apo E3/3 phenotype when matched for intra-abdominal visceral fat accumulation, which has a substantial effect on the metabolism of plasma TG-rich lipoproteins.

Adult↗
PubMed2001

Amphidinolides T2, T3, and T4, new 19-membered macrolides from the dinoflagellate Amphidinium sp. and the biosynthesis of amphidinolide T1.

Three new 19-membered macrolides, amphidinolides T2 (2), T3 (3), and T4 (4), structurally related to amphidinolide T1 (1) have been isolated from two strains of marine dinoflagellates of the genus Amphidinium. The structures of 2-4 were elucidated on the basis of spectroscopic data. The absolute configurations at C-7, C-8, and C-10 of 1-4 were determined by comparison of NMR data of their C-1-C-12 segments with those of synthetic model compounds for the tetrahydrofuran portion. The biosynthetic origins of amphidinolide T1 (1) were investigated on the basis of 13C NMR data of a 13C enriched sample obtained by feeding experiments with [1-(13)C], [2-(13)C], and [1,2-(13)C2] sodium acetates and 13C-labeled sodium bicarbonate in the cultures of the dinoflagellate. These incorporation patterns suggested that amphidinolide T1 (1) was generated from four successive polyketide chains, an isolated C1 unit formed from C-2 of acetates, and three unusual C2 units derived only from C-2 of acetates. Furthermore, it is noted that five oxygenated carbons of C-1, C-7, C-12, C-13, and C-18 were not derived from the C-1 carbonyl, but from the C-2 methyl of acetates.

Animals↗
PubMed2001

The forkhead-associated domain of NBS1 is essential for nuclear foci formation after irradiation but not essential for hRAD50[middle dot]hMRE11[middle dot]NBS1 complex DNA repair activity.

NBS1 (p95), the protein responsible for Nijmegen breakage syndrome, shows a weak homology to the yeast Xrs2 protein at the N terminus region, known as the forkhead-associated (FHA) domain and the BRCA1 C terminus domain. The protein interacts with hMRE11 to form a complex with a nuclease activity for initiation of both nonhomologous end joining and homologous recombination. Here, we show in vivo direct evidence that NBS1 recruits the hMRE11 nuclease complex into the cell nucleus and leads to the formation of foci by utilizing different functions from several domains. The amino acid sequence at 665-693 on the C terminus of NBS1, where a novel identical sequence with yeast Xrs2 protein was found, is essential for hMRE11 binding. The hMRE11-binding region is necessary for both nuclear localization of the complex and for cellular radiation resistance. On the other hand, the FHA domain regulates nuclear foci formation of the multiprotein complex in response to DNA damage but is not essential for nuclear transportation of the complex and radiation resistance. Because the FHA/BRCA1 C terminus domain is widely conserved in eukaryotic nuclear proteins related to the cell cycle, gene regulation, and DNA repair, the foci formation could be associated with many phenotypes of Nijmegen breakage syndrome other than radiation sensitivity.

Amino Acid Sequence↗
PubMed2001

Inferior vena cava occlusion catheter for pediatric patients with heart disease: for more detailed cardiovascular assessments.

Traditional evaluation of cardiac function is too often limited by reliance on measurements with complex interdependence between cardiac properties and loading factors. Analysis by ventricular pressure-volume (P-V), -area (P-A), or -dimension (P-D) relations during inferior vena caval (IVC) occlusion independently quantifies ventricular properties and loading conditions, providing detailed information about cardiovascular dynamics. However, there has been no appropriate size of balloon catheter that can effectively occlude IVC of pediatric patients, hindering the application of P-V (P-A, or P-D) analysis to children with heart disease despite its potential benefit. To address this problem, we have developed a new balloon catheter for IVC occlusion in children. The catheter effectively occluded IVC in 92 pediatric patients with varying forms of heart disease who underwent cardiac catheterization, yielding end-systolic pressure-area relations. Thus a newly developed balloon catheter would contribute to establishing more accurate and detailed cardiovascular assessments in children with heart disease. Cathet Cardiovasc Intervent 2001;53:392-396.

Adolescent↗
PubMed2001

Nucleotide sequence of genome segment 5 from Bombyx mori cypovirus 1.

The complete nucleotide sequences of the double-stranded RNA genome segments 5 (S5) from Bombyx mori cypovirus 1 (BmCPV-1) strains I and H were determined. The segments consisted of 2,852 nucleotides encoding putative proteins of 881 amino acids with molecular masses of approximately 101 kDa (p101). A homology search showed that p101 has high similarity (93%) to foot-and-mouth disease virus (FMDV) 2A protease (2Apro) at amino acid position 219 to 235. These findings suggest the possibility that p101 encoded by BmCPV-1 S5 might be cleaved into two non-structural proteins by post-translational autocleavage involving a 2Apro-like protease.

Amino Acid Sequence↗
PubMed2001

Pulmonary atresia, ventricular septal defect, and coronary-pulmonary artery fistula.

We report 2 patients with pulmonary atresia, ventricular septal defect, and coronary-pulmonary fistula. The fistula originated from the left anterior descending artery in 1 patient, and from the right coronary artery in the other. Both patients survived staged correction in which right ventricular outflow was reconstructed with autologous fistula tissue. One patient with pulmonary hypertension suddenly died 9 months after surgery. Twenty-four patients with pulmonary atresia, ventricular septal defect, and coronary-pulmonary fistula have been reported previously.

Arterio-Arterial Fistula↗
PubMed2001

Tricuspid valve replacement with bioprostheses: long-term results and causes of valve dysfunction.

BACKGROUND: Although the clinical performance of bioprostheses after valve replacement in the aortic and mitral position has been reported, little is known of the performance of tricuspid bioprostheses. The mechanism of bioprosthetic valve dysfunction after tricuspid valve replacement (TVR) is not clear. METHODS: We reviewed 98 cases of TVR with bioprostheses. To clarify the causes of valve dysfunction, pathologic examination of the explanted valve at the reoperation was performed. RESULTS: Actuarial survival at 18 years was 68.7% +/- 5.8%. There were 12 redo TVRs. In six of the 12 cases, isolated redo TVR was performed. In the other cases, concomitant cardiac procedures were performed. The causes of prosthetic valve dysfunction were pannus formation on the cusps of the right ventricle side (four cases), native valve attachment (two cases), pannus formation + native valve attachment (two cases), sclerotic change (one case), pannus formation + sclerotic change (one case), and native valve attachment + valve infection (one case). Freedom from reoperation, structural valve deterioration, and nonstructural dysfunction at 18 years was 62.7% +/- 10.7%, 96.0% +/- 2.9%, and 76.7% +/- 8.3%, respectively. CONCLUSIONS: In our 18 years of experience, although the survival after TVR with bioprostheses is acceptable, the reoperation free rate is not satisfactory. Pannus formation on the cusps of the ventricular side seems to be a serious problem that causes bioprosthetic dysfunction in the tricuspid position.

Adolescent↗
PubMed2001

Pericardiectomy for constrictive pericarditis using the harmonic scalpel.

A 35-year-old man with constrictive pericarditis underwent pericardiectomy. The pericardium was dissected with a Harmonic Scalpel (Ethicon Endo-Surgery, Cincinnati, OH). This new device has many advantages including no muscular stimulation, low heat, a smokeless field, and easy hemostasis. The Harmonic Scalpel is beneficial for dissection of thickened pericardium.

Adult↗
PubMed2001

Transxiphoid approach for intracardiac repair using video-assisted cardioscopy.

Video-assisted cardioscopy (VAC) is a novel tool for providing clear visualization of small intracardiac structures and achieving complete repair in minimally invasive surgery. Between July 1999 and July 2000, 12 patients with atrial septal defect and ventricular septal defect underwent surgical repair using a combined procedure with the transxiphoid approach and VAC in our institution. The mean skin incision was 5.4 cm, and the postoperative courses of all the patients were uneventful without any complications. The mean hospital stay was 8.3 days and 1 patient (8.3%) needed blood products. Our experience showed the technical feasibility and acceptable surgical results of transxiphoid approach using a VAC.

Child, Preschool↗
PubMed2001

Modification of bicaval anastomosis technique for orthotopic heart transplantation.

A modified bicaval anastomosis technique was utilized for 4 consecutive patients undergoing heart transplantation. Instead of transecting the superior and inferior vena cavae, a strip of the posterior right atrial wall was left undivided as a bridge connecting the superior and inferior vena cavae. This minor modification perfectly prevented shrinkage and retraction of the caval tissue, thus providing easier anastomotic orientation and better estimation of the appropriate tissue length that fits well, particularly when a small donor heart was available.

Adolescent↗
PubMed2001

Severe hypertriglyceridemia with plasma inhibitory factor(s) on lipoprotein lipase activity in a patient with a common Ser(447)-Ter LPL mutation.

Severe hypertriglyceridemia is a major risk for acute pancreatitis. So far, several mutations on the lipoprotein lipase (LPL) gene causing type I hyperlipidemia have been identified. However, the common mutation Ser(447)-Ter has been recently proposed to have a lowering effect on serum triglyceride concentrations in the general population. In this study, we analyzed blood from a patient suffering from severe hypertriglyceridemia and pancreatitis with the mutation on the lipoprotein lipase gene, Ser(447)-Ter. The patient's plasma showed inhibitory effects on the LPL activities from normal subjects. The bottom fraction separated by ultracentrifugation revealed enhanced effects as an inhibitory factor. The inhibitory effect observed in the bottom fraction was dose-dependent, stable at treatment of 65 degrees C for 30 min, and decreased significantly after being dialyzed using membranes with a cut-off molecular weight of 3500 or 6000 Da. The inhibitory effect was significantly higher when the post-heparin plasma was used from the patient or a subject with the same LPL mutation as an LPL source, compared to that from normal subjects. These results suggest that the patient has inhibitory factors in his plasma. Such inhibitory factors might cause severe hypertriglyceridemia in a case with the common mutation, which has been proposed to show the lowing effect on serum triglyceride concentrations in the general population.

Acute Disease↗
PubMed2001

Effect of atorvastatin treatment on lipoprotein lipase mass in the pre-heparin plasma in Japanese hyperlipidemic subjects.

BACKGROUND: Atorvastatin is a recently introduced statin that lowers LDL-cholesterol (LDL-C) and triglycerides more than some of the older statins. METHODS: Twenty-one Japanese hyperlipidemic subjects were treated with atorvastatin (10 mg/day) for 6 weeks. Plasma lipid concentrations and pre-heparin plasma LPL mass before and after oral administration were evaluated using an open crossover trial format. LPL mass in the pre-heparin plasma was measured by a sandwich enzyme immunoassay. RESULTS: Atorvastatin decreased plasma triglyceride (TG) concentration (-21%, p<0.05), as well as plasma total and LDL-cholesterol concentrations. LPL mass in the pre-heparin plasma did not change significantly by this treatment during this period. Both apolipoprotein (apo) B and E decreased considerably (-33%, p<0.001 for apo B; -29% p<0.001 for apo E), while apo A-I concentration did not change. Other clinical parameters such as body mass index, blood pressure, and fasting plasma glucose concentration of these subjects did not change during this treatment. CONCLUSIONS: Atorvastatin is effective in reducing plasma TG, which did not appear to be associated with an increased LPL mass.

Aged↗