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Biomedical subjects

H Koyama

Publications and source records attributed to H Koyama.

At least 145 records · Page 8Linked to original sources
PubMed1999

Neutralizing feature of commercially available feline calicivirus (FCV) vaccine immune sera against FCV field isolates.

Four types of commercially available feline calicivirus (FCV) vaccine were compared in terms of their efficacy on the basis of the ability of the sera of specific-pathogen-free cats immunized by two injections of each type of vaccine to neutralize FCV field isolates. Each vaccine immune serum neutralized relatively well strains F4, F9, and 255, which were FCV laboratory strains. As to 36 strains of field isolates, however, vaccines A, B, C, and D immune sera did not neutralize 18-20 of the strains (50.0%-55.6%), 19-22 of the strains (52.8%-61.1%), 22-25 of the strains (61.1%-69.4%), and 8-16 of the strains (22.2%-44.4%), respectively. These results indicate that there is much difference in neutralizing antigenicity between the existing vaccine strains and the FCV strains that are prevalent in Japan, suggesting the need for improvement of FCV vaccines.

Animals↗
PubMed1999

Nasal nocardiosis in a calf.

Nasal nocardiosis was found in a female Japanese Black calf, 11 months of age. Macroscopically, the posterior half of the left nasal passage was completely obstructed by yellowish brown caseous substance and the mucosa was irregularly thickened. In the brain, a few soft brown foci were present in the olfactory bulb and frontal lobe. Microscopically, there were closely packed granulomas in the nasal cavity and brain. The lesions were characterized by a center of cellular debris surrounded by epithelioid macrophages, neutrophils, lymphocytes and multinucleated giant cells of the Langhans type. Special stains revealed the presence of a large number of filamentous branching gram-positive, partially acid-fast organisms in these epithelioid cells and giant cells, and in cellular debris.

Animals↗
PubMed1999

Selection of antigenic variants of the S glycoprotein of feline infectious peritonitis virus and analysis of antigenic sites involved in neutralization.

The type II feline infectious peritonitis virus (FIPV) epitopes for neutralizing and enhancing antibodies are present on large spike glycoprotein (S) protein. In this study, we established monoclonal antibody-resistant mutant viruses resistant to three different monoclonal antibodies with neutralizing activity in Felis catus whole fetus cells and enhancing activity in feline macrophages, recognizing distinct epitopes on type II FIPV S protein. By comparing the nucleotide sequences of these mutant viruses with that of wild-type virus, we attempted to identify the neutralizing epitopes. The mutations were localized in the region of amino acid residues from 480 to 649 from the N terminal of the S protein.

Amino Acid Sequence↗
PubMed1999

The effect of high-dose inhaled beclomethasone dipropionate in patients with stable COPD.

BACKGROUND: The benefits of inhaled corticosteroids in the management of COPD are less apparent than they are in asthma therapy, and the potential for adverse systemic effects of high-dose inhaled corticosteroids has been recognized recently. It is therefore essential to know the maximal obtainable benefits in order to assess the risk/benefit ratio of this treatment. PURPOSE: The aim of this study was to investigate the maximal obtainable benefits of high-dose inhaled corticosteroids, 3 mg/d of beclomethasone dipropionate (BDP), when used in combination with adequate doses of regular bronchodilators in patients with stable COPD. STUDY DESIGN: Thirty patients with stable COPD completed a randomized, double-blind, placebo-controlled cross-over trial with either 3 mg/d of BDP or with a matching placebo using a metered-dose inhaler with a spacer device for 4 weeks during each treatment period. All of the patients continued to inhale both 400 microg of salbutamol qid and 80 microg of ipratropium bromide qid. RESULTS: The mean prebronchodilator FEV1 was 0.97+/-0.35 L during the placebo period and 1.08+/-0.38 L during the BDP period (p < 0.001). While on BDP, five patients demonstrated a response in their FEV1 of more than 8.5% of the predicted value, which was above the range that covered 95% of the distribution of the placebo response. The mean absolute improvement in the FEV1 in these 5 objective responders was 0.34+/-0.10 L, compared to 0.06+/-0.09 L in the 25 objective nonresponders. Symptom scores for wheezing and dyspnea were significantly better with BDP than with placebo. Hoarseness and sore throat were associated more with BDP treatment. CONCLUSION: Although a considerable minority of patients benefited substantially from this treatment, the overall outcome does not seem to justify the widespread use of this treatment in the light of increasing recognition of the potential adverse systemic effects of high-dose inhaled corticosteroids.

Administration, Inhalation↗
PubMed1999

Immunolocalization of tight junction proteins, occludin and ZO-1, and glucose transporter GLUT1 in the cells of the blood-nerve barrier.

Facilitated-diffusion glucose transporter GLUT1 is abundant in the blood-nerve barrier. To observe the relationship between glucose transfer across the barrier and the molecular architecture of the barrier, we examined the localization of GLUT1 and tight junction proteins, occludin and zonula occludens-1 (ZO-1), by immunofluorescence microscopy and immunogold electron microscopy in the rat sciatic nerve. GLUT1 was enriched at the whole aspects of the plasma membranes of the cells of the barrier: perineurial cells, and endothelial cells of the blood vessels in the endoneurium. These GLUT1-positive cells were also positive for occludin and ZO-1, both of which were localized at tight junctions. ZO-1 additionally was present in the GLUT1-negative cells not serving as the blood-nerve barrier. These observations suggest that occludin in the tight junctions and GLUT1 at the plasma membranes in the cells of the barrier may constitute a mechanism for the selective transfer of glucose across the barrier while preventing the non-specific flow of blood constituents.

Animals↗
PubMed1999

Daily response of blood pressure to day-to-day variation of urinary sodium to potassium ratio.

The relationship between blood pressure and urinary sodium-to-potassium (Na/K) ratio was assessed in eight healthy men, none of whom used antihypertensive medications. Blood pressure and urinary sodium and potassium concentrations were measured for 11 to 33 days without any dietary restriction. For two of the eight subjects, the urinary Na/K ratio significantly correlated with systolic blood pressure (r=0.70 and 0.45, respectively), and in one of the two subjects, the urinary ratio also positively correlated with diastolic blood pressure (r=0.72). In the others, no relationship between the ratio and blood pressure was observed (r=-0.24 to 0.26). The results indicate that, in some individuals, the daily variation of urinary Na/K ratio is closely correlated with day-to-day changes in blood pressure level, and suggest that the urinary Na/K ratio is useful in the management of the daily sodium and potassium intake balance of hypertensive patients who need to restrict salt intake.

Adult↗
PubMed1999

[Methicillin-resistant Staphylococcus aureus subdural abscess in an elderly patient with dementia].

A 74-year-old man was admitted to our hospital because of a fever of 38.2 degrees C and drowsiness. Two months before admission, he was admitted to another hospital with the diagnosis of Alzheimer's disease. One week before admission, he had a fever which was judged to be due to pyelonephritis. Because imipenem cilastatin and minocycline were not effective in relieving symptoms, he was transferred to our hospital. Methicillin-resistant Staphylococcus aureus (MRSA) was cultured from the blood, and vancomycin was started on the 5th hospital day. Because of the persistent fever and signs of inflammation, Gallium-scintigraphy was performed, showing abnormal accumulation in the left fronto-parietal region of the brain and the sacral region. Enhanced brain CT revealed a crescentic low density area and a fine, intense line of enhancement in the left fronto-parietal region. An emergency drainage of abscess was performed via single left fronto-parietal burr hole. A slightly yellowish, bloody, purulent fluid was obtained. The subdural space was irrigated with saline containing antibiotics and a drain was inserted. MRSA was cultured from the obtained fluid. The fever gradually subsided and drowsiness disappeared. He had had decubitus ulcer, stage I on the surface, in the sacral region, which later turned out to have unexpectedly deep undermining lesion reaching to periosteum. MRSA was cultured from this decubitus lesion. MRSA which entered into blood stream from the decubitus site might have been implanted in the subdural hematoma. Thus, subdural abscess should be kept in mind as an active differential diagnosis in elderly patients with fever and drowsiness.

Aged↗
PubMed1999

[Descriptive and analytical epidemiology of second primaries in Osaka, Japan].

With the improvement in survival of cancer patients, the incidence of second primaries has been increasing. Data from the Osaka Cancer Registry showed that the incidence of metachronous second primaries was associated with gender (male), age and calendar year at diagnosis of the first cancer. The 10-year cumulative risk was estimated at around 10% for those who developed their first cancer in their sixties in 1978-83. The observed number (O) of second primaries (including synchronous) was compared with the expected number (E). The O/E ratios among those who developed their first cancer at ages 0-14 and 15-29 years old were much higher than the ratios among all age groups. Patients who had developed cancer of the colon, larynx, lung, bladder, or breast (1978-86) showed a significantly higher than expected risk of developing second primaries during the 1-4 years after diagnosis of the first cancer. Based on the hospital cancer registry data from Osaka Medical Center for Cancer and Cardiovascular Diseases, associations between adjuvant chemo-immunotherapy and the risk of second primaries were examined among 1,925 gastric cancer patients who underwent curative gastrectomy. The sex-, age-, and stage-adjusted hazard rate ratio of second primaries was 1.04 for patients who underwent chemotherapy and 0.70 for patients who underwent chemo-immunotherapy, when compared with the risk for patients who did not receive adjuvant chemo-immunotherapy. Some chemotherapeutic agents appeared to increase the risk of second primaries. Second primaries among 2,824 breast cancer patients were examined and their associations with adjuvant chemo-immuno-radiotherapy were analyzed. The O/E ratio for cancers of all sites was 1.28, significantly higher than 1.0. Cancer of the stomach, colon, lung and ovary were frequently observed as a second primary among them. Among 117 patients who developed second primaries, 4 developed cancer of the corpus uteri. This corresponded to 1.89 times the expected, however, only one of the 4 patients underwent tamoxifen treatment. The O/E ratio for non-Hodgkin's lymphoma was 3.40, significantly higher than 1.0. These results suggest associations between the risk for non-Hodgkin's lymphoma and chemotherapy.

Adult↗
PubMed1999

[In vitro activities of levofloxacin and other antibiotics against fresh clinical isolates].

In this study, the in vitro activity of levofloxacin (LVFX) against 1,020 fresh bacterial clinical isolates was compared with the activities of a range of ofloxacin, ciprofloxacin (CPFX), ampicillin (ABPC), cefaclor, cefpodoxime, methicillin and benzylpenicillin. The clinical isolates except Vibrio cholerae were collected in Japan during 1998 from patients with infectious diseases. MICs were determined using the agar dilution method according to the recommendations by the Japan Society of Chemotherapy. Some isolates of methicillin resistant Staphylococcus aureus (MRSA) and coagulase negative Staphylococcus were resistant to fluoroquinolones, but the MIC50 of LVFX against MRSA was 6.25 micrograms/ml. LVFX was the most active against MRSA among the antibiotics tested. Most of Staphylococcus epidermidis strains were susceptible to the fluoroquinolones. LVFX showed greater activity against all streptococci strains compared with fluoroquinolones tested. In particular, all Streptococcus pneumoniae strains including PRSP were susceptible to LVFX at < or = 1.56 micrograms/ml. Among Enterococcus, ABPC showed superior activity against Enterococcus faecalis but many isolates of Enterococcus species were resistant to ABPC. LVFX was more active against to these Enterococcus species compared with other fluoroquinolones. On the other hand, LVFX and CPFX showed similar activity against isolates of Enterobacteriaceae. CPFX had an MIC50/90 of 0.20, 0.39 microgram/ml and LVFX showed an MIC50/90 of 0.78, 1.56 micrograms/ml against Pseudomonas aeruginosa. LVFX (MIC50/90 0.10, 0.20 microgram/ml) was more active against Acinetobacter species than CPFX (MIC50/90 0.10, 0.39 microgram/ml). Haemophilus influenzae, Branhamella (Moraxella) catarrhalis and V. cholerae were inhibited by low concentration of the fluoroquinolones tested. The MIC90 of LVFX and CPFX were < or = 0.10 microgram/ml against above three species. Some isolates of Neisseria gonorrhoeae and Campylobacter species were moderately resistant to the fluoroquinolones tested but the MIC50 of LVFX and CPFX were < or = 0.39 microgram/ml. Among anaerobes, Propionibacterium acnes was more susceptible than Peptostreptococcus species, and the MIC90 of beta-lactams and fluoroquinolones tested were < or = 0.78 microgram/ml. In conclusion, this study, performed on large number of strains, confirmed an excellent and wide spectrum antibacterial activity of LVFX compared with the fluoroquinolones and beta-lactams tested. And our results suggest that LVFX may be useful in the treatment of various bacterial infections.

Ampicillin↗
PubMed1998

Bleomycin enhances random integration of transfected DNA into a human genome.

In mammalian cells, nonhomologous (illegitimate) recombination is a predominant pathway to repair DNA double-strand breaks. We have shown that DNA topoisomerase II inhibitors are capable of enhancing random integration of foreign DNA via nonhomologous recombination. Since this enhancement is likely due to stabilized DNA strand breaks, we examined the effect of a radiomimetic antitumor drug, bleomycin (BLM), on nonhomologous recombination. We found that BLM greatly enhances the random integration of transfected plasmids into human cells. Importantly, this enhancement was independent of the molecular form of the plasmid, the cell type or the transfection method, suggesting that the BLM effect is intrinsically general. Transient expression analysis revealed no stimulation of reporter gene expression by the drug, suggesting that the effect is not attributable to increased uptake and/or accumulation of transfected DNA in the drug-treated cell nuclei. In addition, the comet assay and flow cytometric analyses revealed the occurrence of low but significant strand breaks in cells treated with the BLM concentration which maximally enhanced the integration. These results strongly suggest that BLM acts directly at a nonhomologous recombination reaction that is initiated through DNA strand breaks, promoting the integration process of transfected plasmids into human chromosomes. Our findings will facilitate the understanding of DNA integration events through nonhomologous recombination and the development of transfection protocols with higher efficiencies.

Antibiotics, Antineoplastic↗
PubMed1998

Characterization of the 3' untranslated region of mouse DNA topoisomerase IIalpha mRNA.

Expression of DNA topoisomerase IIalpha protein varies through the cell cycle with its peak in G2/M. This cell-cycle-dependent expression depends on changes in topoisomerase IIalpha mRNA stability as well as promoter activity. We isolated the 3' genomic region of the mouse topoisomerase IIalpha gene and investigated whether or not the 3' untranslated region (UTR) of the topoisomerase IIalpha mRNA participates in the cell-cycle-dependent mRNA stability. Interestingly, genomic- and RT-PCR analyses revealed that the topoisomerase IIalpha 3' UTR is formed via splicing in mouse, but not in human and hamster. Comparison of the mouse 3' region with the human and hamster regions suggests that this mouse-specific splicing has resulted from an accidental acquisition of the consensus 5' splice site. The minority of the non-spliced topoisomerase IIalpha 3' UTR in mouse was confirmed by Northern blot analysis. We performed transient expression assays using luciferase constructs with the mouse topoisomerase IIalpha 3' genomic region, or the major spliced form of the 3' UTR. However, neither construct affected the cell-cycle-dependent expression of the reporter gene driven by the topoisomerase IIalpha promoter. Our results strongly suggest that the mouse topoisomerase IIalpha 3' UTR by itself is not involved in the cell-cycle-dependent mRNA stability.

3T3 Cells↗
PubMed1998

Expression of extracellular matrix proteins accompanies lesion growth in a model of intimal reinjury.

Reinjury of rat arterial lesions induces an increase in lesion size that is not associated with an increase in cell number. In this study, matrix volume was examined after reinjury to preexisting lesions, and the kinetics of matrix gene expression and activity of proteolytic enzymes in the lesion were evaluated. Volume densitometry in intima showed a significant increase in matrix volume 28 days after the reinjury, although no change was observed at 14 days. Three common vascular matrix molecules, alpha1(I)procollagen, tropoelastin, and fibronectin, were expressed highly at 7 days after the reinjury. Expression of tropoelastin remained upregulated for the entire 28 days after the reinjury, whereas alpha1(I)procollagen and fibronectin returned to the control level by 28 days. Protease activity was also increased after reinjury. Within days, a marked increase in urokinase plasminogen activator activity was observed in intima, and this activity decreased to control level by 14 days. The activity of tissue plasminogen activator did not change. The 95-kDa gelatinolytic activity was increased 1 to 2 days after the reinjury, but no change in other gelatinolytic activities was observed. These findings demonstrate that the accumulation of extracellular matrix is important in the increase in lesion size after reinjury and that a balance of matrix synthesis and degradation may explain why no change in matrix volume was detected until 28 days after the reinjury.

Animals↗
PubMed1998

Cell replication in the arterial wall: activation of signaling pathway following in vivo injury.

This study examined intracellular signal events of arterial cells following balloon catheter injury to rat carotid artery. Within 30 minutes, a marked increase in extracellular signal-regulated kinase-1/2 (ERK1/2) activity was observed. This activity remained elevated for 12 hours but had decreased to control levels by day 1. No increase in ERK1/2 was detected at any later times. Injection of anti-fibroblast growth factor 2 antibody (60 mg i.v.) significantly inhibited the activation of ERK1/2 at 30 minutes after the injury. PD98059 (80 micromol/L), a selective inhibitor of mitogen-activated protein kinase/ERK kinase-1 (MEK1), decreased ERK1/2 activity in injured arteries and also reduced the medial cell replication. In contrast, PD98059 did not block the intimal cell replication at day 8. Mitogen-activated protein kinase phosphatase-1 (MKP-1) was expressed within hours after injury but only weakly at later times; MKP-1 was again expressed after 7 and 14 days. The expression of MKP-1 was associated with an activation of c-Jun amino-terminal kinase. Injury to the arterial wall also stimulated the activity of p70 S6 kinase from 30 minutes to 12 hours, suggesting an alternative pathway in mitogenic signaling of early cell replication. These findings demonstrate that fibroblast growth factor 2-induced ERK1/2 activation promotes medial cell replication after balloon injury; however, signaling of intimal cell replication may not be linked to the MEK1-dependent ERK pathway.

Animals↗
PubMed1998

Increases in the mitochondrial DNA replication and transcription in the remnant liver of rats.

We studied mitochondrial DNA (mtDNA) replication and transcription in association with major hepatectomy. Changes in nuclear respiratory factor 1 (NRF-1) mRNA and RNA moiety of mitochondrial RNA-processing endoribonuclease (MRP-RNase RNA) were followed at 0, 3, 6, 12, and 24 h after hepatectomy. Contents of mtDNA, cytochrome b mRNA, and beta-actin mRNA were also measured. Contents of NRF-1 mRNA and MRP-RNase RNA increased to maximum or sub-maximum level 1 h after hepatectomy. mtDNA and cytochrome b mRNA increased to maximum level 3 h after. On the contrary, content of beta-actin mRNA increased to maximum level 12 h after. From these results, mtDNA replication and transcription occurred in the initial phase of liver regeneration, which might lead to an increase in mitochondrial respiratory function in the remnant liver, and cytoskeleton proteins such as beta-actin were followed thereafter.

Actins↗
PubMed1998

Caspase-mediated cleavage of focal adhesion kinase pp125FAK and disassembly of focal adhesions in human endothelial cell apoptosis.

Normal endothelial and epithelial cells undergo apoptosis when cell adhesion and spreading are prevented, implying a requirement for antiapoptotic signals from the extracellular matrix for cell survival. We investigated some of the molecular changes occurring in focal adhesions during growth factor deprivation-induced apoptosis in confluent monolayers of human umbilical vein endothelial cells. Among the first morphologic changes after initiation of the apoptotic process are membrane blebbing, loss of focal adhesion sites, and retraction from the matrix followed by detachment. We observe a specific proteolytic cleavage of focal adhesion kinase (pp125FAK), an important component of the focal adhesion complex, and identify pp125FAK as a novel substrate for caspase-3 and caspase-3-like apoptotic caspases. The initial cleavage precedes detachment, and coincides with loss of pp125FAK and paxillin from focal adhesion sites and their redistribution into the characteristic membrane blebs of apoptotically dying cells. Cleavage of pp125FAK differentially affects its association with signaling and cytoskeletal components of the focal adhesion complex; binding of paxillin, but not pp130(Cas) (Cas, Crk-associated substrate) and vinculin, to the COOH terminally truncated pp125FAK is abolished. Therefore, caspase-mediated cleavage of pp125FAK may be participating in the disassembly of the focal adhesion complex and actively interrupting survival signals from the extracellular matrix, thus propagating the cell death program.

Apoptosis↗
PubMed1998

Role of nerve growth factor in cutaneous wound healing: accelerating effects in normal and healing-impaired diabetic mice.

Four full-thickness skin wounds made in normal mice led to the significant increase in levels of nerve growth factor (NGF) in sera and in wounded skin tissues. Since sialoadenectomy before the wounds inhibited the rise in serum levels of NGF, the NGF may be released from the salivary gland into the blood stream after the wounds. In contrast, the fact that messenger RNA and protein of NGF were detected in newly formed epithelial cells at the edge of the wound and fibroblasts consistent with the granulation tissue produced in the wound space, suggests that NGF was also produced at the wounded skin site. Topical application of NGF into the wounds accelerated the rate of wound healing in normal mice and in healing-impaired diabetic KK/Ta mice. This clinical effect of NGF was evaluated by histological examination; the increases in the degree of reepithelialization, the thickness of the granulation tissue, and the density of extracellular matrix were observed. NGF also increased the breaking strength of healing linear wounds in normal and diabetic mice. These findings suggested that NGF immediately and constitutively released in response to cutaneous injury may contribute to wound healing through broader biological activities, and NGF improved the diabetic impaired response of wound healing.

Animals↗