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Biomedical subjects

K Hayashi

Publications and source records attributed to K Hayashi.

At least 109 records · Page 6Linked to original sources
PubMed2002

Avian retrovirus infection causes naturally occurring glioma: isolation and transmission of a virus from so-called fowl glioma.

So-called fowl glioma is characterized by multiple nodular gliomatous growths associated with disseminated non-suppurative encephalitis. To investigate the possibility of the induction of the gliomatous lesions, chicks of Japanese bantams (Gallus gallus domesticus) and specific pathogen free chickens (C/O strain White Leghorn) were intracerebrally inoculated with a brain homogenate or culture supernatant from a bantam affected with fowl glioma. All bantams and 16 chickens (89%) in the inoculated groups showed non-suppurative encephalitis, and the 18 bantams (82%) and five chickens (28%) developed multiple nodules consisting of aggregations of astrocytes in the cerebrum. These astrocytes had avian leukosis virus (ALV) antigen. By Southern blot analysis, the ALV sequence was detected both in DNA prepared from the brains of the inoculated birds and in DNA from the inoculum. Ultrastructurally, tadpole-shaped particles, approximately 100 nm in diameter, were detected in the concentrated supernatant of the chicken embryo fibroblasts, and budding of the particles was noted. These results substantiated that fowl glioma of the bantams could be transmitted by intracerebral inoculation of the affected tissue and that the causal agent was an unidentified strain of ALV.

Animals↗
PubMed2002

Pseudoalteromonas translucida sp. nov. and Pseudoalteromonas paragorgicola sp. nov., and emended description of the genus.

On the basis of phenotypic and genotypic characteristics and analysis of 16S rRNA sequences, two novel species belonging to the genus Pseudoalteromonas are described. A pale-orange-pigmented strain, KMM 3548T, isolated from a sponge and a non-pigmented strain, KMM 520T, isolated from sea water are marine, gram-negative, aerobic, rod-shaped organisms. One of the strains, KMM 520T, had bipolar flagella. Both strains had the ability to degrade gelatin, DNA and Tween 80 but not chitin or agar. Strain KMM 520T decomposed elastin and grew at NaCl concentrations of 1-8%, while strain KMM 3548T grew at 1-6% NaCl. The temperature range for both strains was 4-30 degrees C. The DNA G+C contents were 46.3 (KMM 520T) and 41.1 mol% (KMM 3548T). The level of DNA relatedness between the two strains was 20%. DNA from strain KMM 520T showed 8-34% genetic relatedness and that of KMM 3548T showed 17-53% relatedness to the DNA of other type strains of the genus Pseudoalteromonas. 16S rRNA analysis indicated a clear affiliation of these novel bacteria with the genus Pseudoalteromonas. The type strains of the novel species are Pseudoalteromonas translucida sp. nov. KMM 520T (= LMG 19696T = ATCC BAA-3157T) and Pseudoalteromonas paragorgicola sp. nov. KMM 3548T (= LMG 19694T = ATCC BAA-322T).

Animals↗
PubMed2002

Frequency of ciliary body or retinal breaks and retinal detachment in eyes with atopic cataract.

AIM: To determine the frequency of ciliary body or retinal breaks and retinal detachment in eyes with atopic cataract. METHODS: The records of 106 eyes (74 patients) with atopic cataract that underwent cataract extraction were reviewed. The frequency of ciliary body or retinal breaks and retinal detachment was classified by their presence preoperatively and postoperatively, and by cataract type. RESULTS: Breaks were detected preoperatively in 27 eyes (25.5%) of 17 patients in the ciliary body (20 eyes, 18.9%), near the ora serrata (five eyes, 4.7%), and in undefined locations (two eyes, 1.9%). Among these, 16 eyes (15.1%) had already developed retinal detachment. After surgery, a ciliary body break occurred in one eye (0.9%) and retinal detachment in four eyes (3.8%) of three patients. The breaks that caused postoperative retinal detachment were in the ciliary body. When classified by cataract type, the highest frequency of breaks was associated with mature cataracts (35.0%), and all eyes with breaks developed retinal detachment. CONCLUSIONS: One fourth of eyes with atopic cataract had breaks in the ciliary body or ora serrata, or retinal detachment preoperatively. The highest frequency of either breaks or retinal detachment was associated with mature cataract. The frequency of breaks or detachment that occurred postoperatively (approximately 5%) was lower than that present preoperatively.

Adolescent↗
PubMed2002

Fixation of osteochondral lesions of the talus using cortical bone pegs.

We have treated osteochondral lesions of the talus using cortical bone pegs. We examined 27 ankles (27 patients) after a mean follow-up of 7.0 years (2 to 18.8). The mean age of the patients was 27.8 years (12 to 62). An unstable osteochondral fragment or osteosclerotic changes in the bed of the talus were regarded as indications for the procedure. The clinical results were good in 24 ankles (89%) and fair in three (11%); none had a poor result. There was also radiological improvement in 24 ankles. Repair of the articular surface and stability of the lesion can be achieved even in unstable chronic lesions.

Adolescent↗
PubMed2002

Animal in vivo models of EBV-associated lymphoproliferative diseases: special references to rabbit models.

Animal models of human EBV-associated diseases are essential to elucidate the pathogenesis of EBV-associated diseases. Here we review those previous models using EBV or EBV-like herpesviruses and describe the details on our two newly-developed rabbit models of lymphoproliferative diseases (LPD) induced by simian EBV-like viruses. The first is Cynomolgus-EBV-induced T-cell lymphomas in rabbits inoculated intravenously (77-90%) and orally (82-89%) during 2-5 months. EBV-DNA was detected in peripheral blood by PCR from 2 days after oral inoculation, while anti-EBV-VCA IgG was raised 3 weeks later. Rabbit lymphomas and their cell lines contained EBV-DNA and expressed EBV-encoded RNA-1 (EBER-1). Rabbit lymphoma cell lines, most of which have specific chromosomal abnormality, showed tumorigenicity in nude mice. The second is the first animal model for EBV-infected T-cell LPD with virus-associated hemophagocytic syndrome (VAHS), using rabbits infected with an EBV-like herpesvirus, Herpesvirus papio (HVP). Rabbits inoculated intravenously with HVP-producing cells showed increased anti-EBV-VCA-IgG titers, and most (85%) subsequently died of fatal LPD and VAHS, with bleeding and hepatosplenomegaly, during 22-105 days. Peroral spray of cell-free HVP induced viral infection with seroconversion in 3 out of 5 rabbits, with 2 of the 3 infected rabbits dying of LPD with VAHS. Atypical T lymphocytes containing HVP-DNA and expressing EBER-1 were observed in many organs. Hemophagocytic histiocytosis was observed in the lymph nodes, spleen, bone marrow, and thymus. These rabbit models are also useful and inexpensive alternative experimental model systems for studying the biology and pathogenesis of EBV, and prophylactic and therapeutic regimens.

Animals↗
PubMed2002

The cooperative action of angiotensin II with subluteolytic administration of PGF2alpha in inducing luteolysis and oestrus in the cow.

There is evidence that the potent vasoconstrictor angiotensin II (Ang II) regulates luteal functions. In the present study, the effect of an intraluteal injection of Ang II alone or in combination with pretreatment with a subluteolytic i.m. dose of PGF(2alpha) on the concentration of plasma progesterone, corpus luteum regression and duration of the oestrous cycle was investigated. Cows were assigned randomly to receive an intraluteal injection of either: (i) 500 microl saline 30 min after i.m. administration of saline (control, n = 7); (ii) 500 microl saline 30 min after i.m. administration of a subluteolytic dose (125 microg) of a PGF(2alpha) analogue (1/4 PGF(2alpha), n = 5); (iii) 2 mg Ang II in 500 microl saline 30 min after i.m. administration of saline (Ang II, n = 5); or (iv) 2 mg Ang II in 500 microl saline 30 min after i.m. administration of a subluteolytic dose (125 microg) of the PGF(2alpha) analogue (1/4 PGF(2alpha)/Ang II, n = 6) on day 12 of the oestrous cycle. There were no significant changes in plasma progesterone concentrations in the control, 1/4 PGF(2alpha) or Ang II treatment groups. Treatment with 1/4 PGF(2alpha)/Ang II decreased plasma progesterone concentration, and induced luteolysis and oestrus. The onset of oestrus in cows treated with full-dose (500 microg) PGF(2alpha) (3.1 +/- 0.2 (mean +/- SEM) days after treatment) was significantly earlier than that in cows treated with 1/4 PGF(2alpha)/Ang II (4.8 +/- 0.2 days after treatment) (P < 0.05). The results from the present study demonstrate that an intraluteal injection of Ang II after i.m. administration of a subluteolytic dose of PGF(2alpha) analogue induces luteolysis and oestrus. Thus, these results support the contention that Ang II is directly correlated with the process of luteal regression in cows.

Angiotensin II↗
PubMed2002

Comparative effects of plasmapheresis and intravenous cyclophosphamide on urinary podocyte excretion in patients with proliferative Lupus nephritis.

Intravenous cyclophosphamide (IVC) in combination with steroids is standard therapy for Lupus nephritis. Reduction of autoantibodies and circulating immune complexes can be used in the treatment of autoimmune diseases. The aim of the present study was to compare the effects of IVC pulse therapy and double-filtration plasmapheresis (DFPP) on proteinuria and urinary excretion of podocytes in adult patients with diffuse proliferative Lupus nephritis (DPLN). Twenty patients were randomly assigned to two groups. Group A (n = 10) was treated with IVC (0.75 - 1.0 g/m2 body surface area) pulse therapy, given as boluses once a month for 6 consecutive months, combined with oral corticosteroid (up to 1 mg/kg/day) administration. Group B (n = 10) was treated with a combination of DFPP (performed 1-2 times weekly) and corticosteroid (up to I mg/kg/ day). The total average number of treatments was 8.4 and the therapeutic efficacies were evaluated after 6 months. Twenty healthy individuals participated as a control group. Urinary podocytes were examined by immunofluorescence with monoclonal antibodies against podocalyxin. Both Group A and Group B reduced proteinuria (p < 0.001) as well as the number of urinary podocytes (p < 0.001). Differences between the 2 treatment outcomes were not statistically significant. Cyclophosphamide pulse therapy and DFPP may be similarly effective in the treatment of podocyte injury in patients with DPLN.

Adult↗
PubMed2002

[Esophagopericardial fistula occurring at the 22nd years after operation for achalasia presenting as myopericarditis].

We describe a case of pneumopericardium that resulted from esophagopericardial fistula occurring at the 22nd years after operation for achalasia in a 52-year-old male. Atypical features on initial examination suggested myopericarditis or congestive heart failure. A chest roentgenogram and computed tomography revealed development of pneumopericardium. Subsequent emergent pericardiocentesis relieved cardiac tamponade and enabled us to diagnose pyopneumopericardium and esophagopericardial fistula in postoperative period. The esophagopericardial fistula was surgically closed. However, the patient died 2 weeks postoperation of hemorrhage from duodenal ulcer. Autopsy confirmed the pre-mortem diagnosis of esophagopericardial fistula without evidence of malignancy. Early diagnosis and subsequent treatment appears to be most important. This case report reinforces the difficulty of this diagnosis and perhaps the need for clinical awareness and inclusion of this entity in a differential diagnosis.

Cardiac Tamponade↗
PubMed2002

[Influence of preoperative factors on off-pump coronary aortic bypass grafting success].

Heart displacement during off-pump CABG (OPCAB) might induce the hemodynamic instability. We attempted to show which preoperative factors would contribute to an increase in that incident during OPCAB. Between February 2000, and October 2000, 51 patients underwent CABG in Okamura Memorial Hospital. Of these patients, 42 patients (82.4%) underwent OPCAB and 9 patients (17.6%) were operated upon under cardiac arrest with cardiopulmonary bypass (NOPCAB). To expose target coronary arteries for OPCAB, 3 deep pericardial traction stitches were placed near the left lower pulmonary vein (LPV), the left of the inferior vena cava (IVC) and the mid portion between LPV and IVC. To further assist in providing good presentation, patients were placed in Trendelenburg position (30 degree head-down tilt) and the right decubitus (30 degree the right side-down tilt). There were no OPCAB patients to be converted to on-pump CABG during anastomosis. Mean number of grafts in OPCAB group was 2.5 +/- 0.1 per patient, while that in NOPCAB group was 3.4 +/- 0.2 (p < 0.01). The bypass patient rate were 97.1% (100/103) in OPCAB group and 100% (31/31) in NOPCAB group (p = NS). In both groups, bilateral internal thoracic arteries were actively used for reperfusion to the left coronary artery. In the preoperative catheterization findings, pulmonary capillary wedge pressure (PCW) and left ventricular end-diastolic pressure (LVEDP) were significantly higher in NOPCAB group than those in OPCAB group (PCW: 14.0 vs 7.9 mmHg, LVEDP: 14.0 vs 8.7 mmHg: p < 0.05), and there was a tendency of low preoperative ejection fraction (EF) and cardiac index (CI) in NOPCAB group compared with those in OPCAB group, although there were no differences in left ventricular end-diastolic and end-systolic volume index (LVEDVI and LVESVI) between both groups. These findings suggested that PCW and LVEDP within the normal limit could be credited for the success with OPCAB, while an increase of the left ventricular volume would not contribute to the actual success.

Aged↗
PubMed2001

Structure-based generation of a new class of potent Cdk4 inhibitors: new de novo design strategy and library design.

As a first step in structure-based design of highly selective and potent Cdk4 inhibitors, we performed structure-based generation of a novel series of Cdk4 inhibitors. A Cdk4 homology model was constructed according to X-ray analysis of an activated form of Cdk2. Using this model, we applied a new de novo design strategy which combined the de novo design program LEGEND with our in-house structure selection supporting system SEEDS to generate new scaffold candidates. In this way, four classes of scaffold candidates including diarylurea were identified. By constructing diarylurea informer libraries based on the structural requirements of Cdk inhibitors in the ATP binding pocket of the Cdk4 model, we were able to identify a potent Cdk4 inhibitor N-(9-oxo-9H-fluoren-4-yl)-N'-pyridin-2-ylurea 15 (IC(50) = 0.10 microM), together with preliminary SAR. We performed a docking study between 15 and the Cdk4 model and selected a reasonable binding mode which is consistent with the SAR. Further modification based on the proposed binding mode provided a more potent compound, N-[(9bR)-5-oxo-2,3,5,9b-tetrahydro-1H-pyrrolo[2,1-a]isoindol-9-yl]-N'-pyridin-2-ylurea 26a (IC(50) = 0.042 microM), X-ray analysis of which was accomplished by the soaking method. The predicted binding mode of 15 in Cdk4 was validated by X-ray analysis of the Cdk2-26a complex.

CDC2-CDC28 Kinases↗
PubMed2001

A novel approach for the development of selective Cdk4 inhibitors: library design based on locations of Cdk4 specific amino acid residues.

Identification of a selective inhibitor for a particular protein kinase without inhibition of other kinases is critical for use as a biological tool or drug. However, this is very difficult because there are hundreds of homologous kinases and their kinase domains including the ATP binding pocket have a common folding pattern. To address this issue, we applied the following structure-based approach for designing selective Cdk4 inhibitors: (1) identification of specifically altered amino acid residues around the ATP binding pocket in Cdk4 by comparison of 390 representative kinases, (2) prediction of appropriate positions to introduce substituents in lead compounds based on the locations of the altered amino acid residues and the binding modes of lead compounds, and (3) library design to interact with the altered amino acid residues supported by de novo design programs. Accordingly, Asp99, Thr102, and Gln98 of Cdk4, which are located in the p16 binding region, were selected as first target residues for specific interactions with Cdk4. Subsequently, the 5-position of the pyrazole ring in the pyrazol-3-ylurea class of lead compound (2a) was predicted to be a suitable position to introduce substituents. We then designed a chemical library of pyrazol-3-ylurea substituted with alkylaminomethyl groups based on the output structures of de novo design programs. Thus we identified a highly selective and potent Cdk4 inhibitor, 15b, substituted with a 5-chloroindan-2-ylaminomethyl group. Compound 15b showed higher selectivity on Cdk4 over those on not only Cdk1/2 (780-fold/190-fold) but also many other kinases (>430-fold) that have been tested thus far. The structural basis for Cdk4 selective inhibition by 15b was analyzed by combining molecular modeling and the X-ray analysis of the Cdk4 mimic Cdk2-inhibitor complex. The results suggest that the hydrogen bond with the carboxyl group of Asp99 and hydrophobic van der Waals contact with the side chains of Thr102 and Gln98 are important. Compound 15b was found to cause cell cycle arrest of the Rb(+) cancer cell line in the G(1) phase, indicating that it is a good biological tool.

Adenosine Triphosphate↗
PubMed2001

Translesional synthesis past acetylaminofluorene-derived DNA adducts catalyzed by human DNA polymerase kappa and Escherichia coli DNA polymerase IV.

Human DNA polymerase kappa (pol kappa) has a sequence significantly homologous with that of Escherichia coli DNA polymerase IV (pol IV). We used a truncated form of human pol kappa (pol kappaDeltaC) and full-length pol IV to explore the miscoding properties of these enzymes. Oligodeoxynucleotides, modified site-specifically with N-(deoxyguanosin-8-yl)-2-acetylaminofluorene (dG-AAF) and N-(deoxyguanosin-8-yl)-2-aminofluorene (dG-AF), were used as DNA templates in primer extension reactions that included all four dNTPs. Reactions catalyzed by pol kappaDeltaC were partially blocked one base prior to dG-AAF or dG-AF, and also opposite both lesions. At higher enzyme concentrations, a significant fraction of primer was extended. Analysis of the fully extended reaction product revealed incorporation of dTMP opposite dG-AAF, accompanied by much smaller amounts of dCMP, dAMP, and dGMP and some one- and two-base deletions. The product terminating 3' to the adduct site contained AMP misincorporated opposite dC. On templates containing dG-AF, dAMP, dTMP, and dCMP were incorporated opposite the lesion in approximately equal amounts, together with some one-base and two-base deletions. Steady-state kinetics analysis confirmed the results obtained from primer extension reactions catalyzed by pol kappa. In contract, primer extension reactions catalyzed by pol IV were blocked effectively by dG-AAF and dG-AF. At high concentrations of pol IV, full-length products were formed containing primarily one- or two-base deletions with dCMP, the correct base, incorporated opposite dG-AF. The miscoding properties of pol kappa observed in this study are consistent with mutational spectra observed when plasmid vectors containing dG-AAF or dG-AF are introduced into simian kidney cells [Shibutani, S., et al. (2001) Biochemistry 40, 3717-3722], supporting a model in which pol kappa plays a role in translesion synthesis past acetylaminofluorene-derived lesions in mammalian cells.

2-Acetylaminofluorene↗
PubMed2001

Expression of hepatocyte growth factor activator and hepatocyte growth factor activator inhibitor type 1 in human hepatocellular carcinoma.

Hepatocyte growth factor activator inhibitor type 1 (HAI-1), a Kunitz-type serine protease inhibitor for hepatocyte growth factor activator (HGFA), is responsible for proteolytic activation of hepatocyte growth factor. We examined the expression of HGFA and HAI-1 in liver tissues of chronic liver diseases including hepatocellular carcinoma (HCC). HGFA expression was detected not only in the liver tissues of chronic hepatitis and cirrhosis and in the nontumorous liver tissues surrounding HCC, but also in HCC tissues. On the other hand, none of the liver tissues of hepatitis and cirrhosis and none of the nontumorous tissues surrounding HCC were stained with anti-HAI-1. However, 35% of HCC tissues were stained with anti-HAI-1, and HAI-1 positivity increased as the histological grade decreased and as serum alpha-fetoprotein increased. Transduction of antisense HAI-1 inhibited the growth of human hepatoma cells. These results suggest the possibility that HAI-1 plays an important role in the progression of HCC.

Base Sequence↗
PubMed2001

Overexpression of AML1 transcription factor drives thymocytes into the CD8 single-positive lineage.

To understand the gene regulation involved in the development of single-positive (SP) thymocytes, we generated transgenic mice in which the AML1 transcription factor is overexpressed. In these mice the number of CD8 SP thymocytes was greatly increased, and this continued to be true even when MHC class I was absent. This promotion to the CD8 SP lineage was not, however, observed when both class I and class II were absent. Furthermore, even thymocytes carrying MHC class II-restricted TCR differentiated into the CD8 SP lineage when AML1 was overexpressed. The selected CD8 SP cells were, however, unable to mature, as judged by the expression level of heat-stable Ag. Thus, overexpression of AML1 is able to skew class II-restricted thymocytes into the CD8 SP lineage, but not to drive the maturation of resulting selected CD8 SP cells.

Animals↗
PubMed2001

A newly established strain of spontaneously hypertensive rat with a defect of ascorbic acid biosynthesis.

To investigate the effects of ascorbic acid deficiency on the pathogenesis of hypertension and/or its complications, we established a rat strain with both genetic hypertension and a defect of ascorbic acid biosynthesis. The od gene (L-gulono-gamma-lactone oxidase gene) of the ODS (Osteogenic Disorder Shionogi) rat, which is a rat mutant unable to synthesize ascorbic acid, was introduced into spontaneously hypertensive rats (SHR), and a novel congenic strain, SHR-od, was established. SHR-od showed scurvy when fed an ascorbic acid-free diet. Systolic blood pressure of male SHR-od began to increase at 9 weeks of age and reached 190-200 mmHg at 20 weeks of age. In 25-week-old SHR-od, ascorbic acid deficiency when fed an ascorbic acid-free diet for 6 weeks caused a remarkable reduction of blood pressure to lower than 110 mmHg. The wall to lumen ratio of the testicular artery in ascorbic acid-deficient SHR-od was lower than that of the control rats. When rats were fed a diet supplemented with ascorbic acid (300 mg/kg), ascorbic acid concentration in SHR-od was lower in the serum and liver than that in ODS rats. These results indicate that ascorbic acid could be closely related to the development of hypertension in SHR-od. We believe that SHR-od will be a useful model for experimental studies on hypertension and its complications, since all of them suffer from hypertension spontaneously and the level of ascorbic acid deficiency in these rats could be controlled at will both in concentration and duration.

Aging↗
PubMed2001

Roles of mast cells and sensory nerves in cutaneous vascular hyperpermeability and scratching behavior induced by poly-L-arginine in rats.

We investigated whether the polycation poly-L-arginine elicited cutaneous vascular hyperpermeability and scratching behavior and, if so, whether these responses involved mast cells and sensory nerves in rats. Intradermal injections of poly-L-arginine induced vascular hyperpermeability and scratching behavior. Combined treatment with chlorpheniramine and methysergide almost completely suppressed the poly-L-arginine (50 microg/site)-induced plasma leakage. Capsaicin desensitization and the tachykinin NK(1) receptor antagonist LY303870, (R)-1-[N-(2-methoxybenzyl)acetylamino]-3-(1H-indol-3-yl)-2-[N-(2-(4-(piperidin-1-yl)piperidin-1-yl)acetyl)amino]propane, partially inhibited the leakage. In mast cell-deficient rats, poly-L-arginine only minimally induced plasma leakage. On the other hand, capsaicin desensitization and LY303870, but not chlorpheniramine or methysergide, suppressed the poly-L-arginine (200 microg/site)-induced scratching. Moreover, poly-L-arginine elicited the scratching even in mast cell-deficient rats. These results suggest that substance P is at least partly involved in both the cutaneous plasma leakage and the scratching behavior induced by poly-L-arginine. Moreover, mast cell-derived amines are suggested to be involved in the plasma extravasation but scarcely, if any, in the scratching behavior.

Animals↗