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Biomedical subjects

Y Murakami

Publications and source records attributed to Y Murakami.

At least 775 records · Page 43Linked to original sources
PubMed1990

[Study on prototype cylindrical HAP].

Hydroxyapatite (HAP) is currently utilized as biomaterials for implantation or reconstruction of bone defect in dentistry. In order to obtain better physical properties and biocompatibility, we have developed cylindrical sintered porous HAP which has longitudinal internal tubules. We measured compressive strength and specific surface area of cylindrical HAP. In the results, compressive strength was more 300MPa on average and specific surface area was 1.7-2.4 folds as HAP ceramics commercially available. This result indicates new bone formation. Cylindrical HAP used was subsequently applied to lower premolars and molars of male beagle dogs (1.5 years). We have implanted cylindrical HAP to bone defect of postextraction of tooth followed to sacrifice six months after. Specimens of bone block were stained with Villanueva bone stain and observed with fluorescence microscope and scanning electron microscope. New tissue formation was observed invading into tubules of 27 microns diameter of cylindrical HAP particles. This new tissue was confirmed to be bone tissue because the proportion of Ca to P was 1.616 obtained by energy dispersive X-ray analyzer.

Alveolar Bone Loss↗
PubMed1990

[T cell blastogenesis in stored blood can induce GVHD in open heart surgery].

We studied T cell blastogenesis in stored blood during the preservation time within 7 days. Blood samples were obtained from 8 adults and stored at 4 degrees C immediately after donation with CPD (citrate-phosphate-dextrose) for 3,5 and 7 days. After each intervals, mitogenic responses of T cells from the samples in the presence of an optimal dose of PHA as a mitogen and MLR (mixed lymphocyte reaction) with lymphocytes prepared by 2000 rad radiation from other 10 donors as stimulating cells were investigated. The stimulation index (S.I.) of PHA as a responsibility of the stored blood was decreasing to 86.7 +/- 24.8%, 44.2 +/- 12.5% and 31.2 +/- 11.1% in proportion of that of fresh blood after 3, 5 and 7 days preservation. The S.I. of MLR were in the same way decreasing to 92.5 +/- 21.8%, 45.9 +/- 9.8% and 33.3 +/- 10.1% after that. These observations suggest that lymphocytes in stored blood within 7 days are able to induce GVHD (graft-versus-host disease) in open heart surgery of which immunological activity is thought to be decreased by extra-corporeal circulation. We concluded that the stored blood within 7 days should be irradiated to 1500 rad or more in order to prevent GVHD.

Adult↗
PubMed1990

A tumor promoting phorbol ester, TPA, enhances polyomavirus DNA replication by activating the function of the viral enhancer.

The effect of tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA) on enhancer dependent polyomavirus (Py) DNA replication was examined in cells expressing Py large T antigen. The results showed that TPA enhanced Py DNA replication by stimulating the activity of the A element, one of the two cores of Py enhancer. Of the three subdomains of the A element, the biding sites of PEBP1 (PEA1), a member of AP1 family, and of PEBP5 were by themselves able to activate Py DNA replication. Furthermore, each binding site of PEBP1 and PEBP5 responded to TPA to enhance Py DNA replication. The results suggest that growth promoting signals could activate DNA replication directly via enhancer binding proteins.

Antigens, Polyomavirus Transforming↗
PubMed1990

[Legionellosis].

Although increasing attention is being given to Legionella pneumonia in Japan, reports of solitary onset of this disease are scant in Japan. The patient, from whom L. dumoffii was isolated, was a 59-year-old male with no underlying disease. He visited our hospital because of fever and cough, and was admitted to our department for X-ray findings consistent with pneumonia. After admission, pulmonary lesions spread rapidly, and based on the suspicion of Legionella pneumonia, drugs such as EM, RFP and MINO were used. However, the patient died on the 26th hospital day. L. dumoffii was isolated from specimens obtained by airway aspiration before death and specimens of lung abscess and airway discharge obtained during autopsy (7 specimens in total). In addition, the L. dumoffii antibody titer in the serum became elevated. This is the first case of L. dumoffii pneumonia reported in Japan. The other case was in an 81-year-old male with underlying disease. He was admitted urgently with suspected pneumonia but died on the following day. L. pneumophila serogroup 5 was isolated from autopsied lung tissue. Fatality is high for this disease, making early diagnosis and treatment with appropriate antibiotics essential. Physicians should bear in mind the possibility of this disease and request the necessary laboratory tests in suspected cases without delay.

Aged↗
PubMed1990

[Protective effect of calcium channel blockers on the liver against halothane hepatitis in rats].

This study examined whether nifedipine or flunarizine, calcium channel blockers, could protect the liver against halothane hepatotoxicity in rats. Six groups of 102 enzyme-induced male Sprague-Dawley rats were studied. Group N1 and N2 rats received nifedipine 20 micrograms and 100 micrograms.kg-1.day-1, and group F1 and F2 rats received flunarizine 100 micrograms and 1mg.kg-1.day-1 in their drinking water for 24 hours prior to the experiment. They were then anesthetized with N2-O2-halothane 0.5% under the condition of hypoxia (FIO2 0.12) for two hours. Animals in group H were given clear water, and then anesthetized with halothane and hypoxia. Animals in group C were given clear water and exposed to hypoxia alone. Twenty-four hours after anesthesia, all animals were decapitated and their liver specimens were stained with H&E for the examination by light microscopy. Eighty percent of rats in group H showed centrilobular degeneration, but administration of nifedipine or flunarizine reduced the incidence significantly. Furthermore, histological score graded from 0 to 3, according to the degree of centrilobular degeneration was also significantly reduced by administration of nifedipine or flunarizine. These results suggest that oral administration of nifedipine or flunarizine could prevent the incidence of halothane-induced hepatotoxicity in enzyme-induced rats, probably by preventing the increase in cytosolic calcium concentration.

Animals↗
PubMed1990

[Annual changes in isolation of MRSA in our department and chemotherapeutic effect of antibiotics including minocycline against postoperative infections of methicillin-resistant S. aureus].

Assessment has been made, using MIC values and coagulase types, of 214 strains of Staphylococcus aureus isolated from the lesions of inpatients at the First Surgical Department, Hiroshima University, from 1983 to 1988. The obtained results are summarized below: 1. Frequency of MRSA among all the strains of S. aureus during a period from 1983 to 1987 was higher than 50%. 2. Highly methicillin-resistant strains (MIC of methicillin greater than 100 micrograms/ml) emerged in 1984 and thereafter, showed a trend of increase through 1987. 3. The highly methicillin-resistant strains are of coagulase II type strain and they are considered to be inhospital epidemic strains. 4. Both ofloxacin and minocycline (MINO) showed good activities against highly methicillin-resistant strains, but many resistant strains were resistant to beta-lactam and aminoglycoside agents. Based on the above basic assessment, chemotherapies mainly using MINO were performed on cases of MRSA infections experienced at the First Surgical Department, Hiroshima University in a period from July, 1987, to November, 1988, and the following results were obtained. 1. Drugs used were: single MINO in 2 cases; MINO+imipenem/cilastatin (IPM/CS) in 4 cases; MINO+IPM/CS+tobramycin in 1 case; MINO+cefmetazole (CMZ) in 1 cases; and MINO+fosfomycin+CMZ (changed to MINO+Amikacin) in 1 case, a total of 9 cases. Clinical result showed remarkable effectiveness of these therapies in 3 cases with some degrees of effectiveness in 6 cases, thus the therapies were all effective or better. 2. No particular abnormality was observed in subjective or objective symptoms or clinical laboratory tests, judged from values obtained before and after administration of MINO. The above results agreed with well those of the basic assessment, suggesting the possibility that the chemotherapies mainly using MINO would exhibit effectiveness on MRSA infections.

Adult↗
PubMed1990

[Pituitary hyperplasia in primary hypothyroidism].

One case of primary hypothyroidism with hyperplasia of the pituitary gland was reported. This enlargement was decreased after hormone replacement therapy. Pituitary hyperplasia occurs secondarily to primary endocrine gland failure. Reactive enlargement of the pituitary gland must be differentiated from primary pituitary abnormalities in order to avoid unnecessary surgery.

Adolescent↗
PubMed1989

Irreversible inhibition of v-src tyrosine kinase activity by herbimycin A and its abrogation by sulfhydryl compounds.

Herbimycin A, an antibiotic which reverses Rous sarcoma virus transformation, inhibited irreversibly the auto- and trans-phosphorylation activities of p60v-src in in vitro immune complex kinase assays. The addition of a sulfhydryl compound such as dithiothreitol, 2-mercaptoethanol, glutathione (reduced form) or cysteine abolished the ability of herbimycin A to inactivate p60v-src kinase as well as the ability to reverse transformed cell morphology, whereas the addition of oxidized glutathione, cystine or methionine showed no effect. The sulfhydryl alkylating reagent N-ethylmaleimide also, although less effectively, inactivated p60v-src kinase activity in vitro. These results suggest the likelihood that sulfhydryl groups of p60v-src are involved in the inactivation of v-src tyrosine kinase activity by herbimycin A.

Benzoquinones↗
PubMed1989

[Temporal changes in internal echoes in hepatic hemangiomas].

We have discovered a fact that there is a temporal changes of internal echo levels in hepatic hemangiomas. Nine hemangiomas in 6 cases diagnosed by CT were studied ultrasonographically by the real-time scanner during the observation period from 4 to 30 minutes. Low echo portions occupying within the tumor (low echo level ratio) showed temporal changes in 8 of 9 hemangiomas during this period. It is important to take temporal factors into consideration for the ultrasonographic diagnosis of hepatic masses. We coined the term "wax and wane" sign to the temporal changes of internal echo levels in the hepatic hemangioma.

Adult↗
PubMed1989

Novel and sensitive noncompetitive enzyme immunoassay for kassinin in rat plasma.

A novel and sensitive noncompetitive enzyme immunoassay for kassinin is described. Kassinin was biotinylated using sulfosuccinimidyl-6-(biotinamido)hexanoate. The biotinylated kassinin was trapped on anti-kassinin IgG-coated polystyrene balls and, after washing to eliminate other biotinylated substances, was eluted with HCl. The biotinylated kassinin eluted was reacted with anti-kassinin Fab'-peroxidase conjugate and trapped onto streptavidin-coated polystyrene balls. Peroxidase activity bound to the polystyrene balls was assayed by fluorimetry. The detection limit of kassinin was 0.13 pg (0.1 fmol)/tube or 0.065 microgram/l of rat plasma, which was 750-fold or 15-fold lower than that for competitive radioimmunoassay.

Animals↗
PubMed1989

Properties and fluctuations in vivo of rat liver antizyme inhibitor.

Antizyme inhibitor was highly purified from rat liver by using affinity chromatography. It has some structural resemblance to ornithine decarboxylase (ODC), as judged from Mr, immunoreactivity and reversible binding with antizyme. However, unlike hepatic amounts of ODC and ODC-antizyme complex, that of antizyme inhibitor did not show much fluctuation upon putrescine treatment, whereas it decreased as rapidly as ODC decay in the presence of cycloheximide. These results suggested that antizyme inhibitor is an independent regulatory protein rather than a derivative of ODC. Changes in hepatic amounts of antizyme inhibitor, antizyme and ODC upon feeding suggested that antizyme inhibitor may play a role in ODC regulation by trapping antizyme and thereby suppressing ODC degradation. A monoclonal antibody to rat liver antizyme inhibitor was obtained. This antibody was shown to be utilizable for a simple assay of antizyme-inhibitor activity in tissue extracts.

Animals↗
PubMed1989

Amino acid sequence of Mirabilis antiviral protein, total synthesis of its gene and expression in Escherichia coli.

We have determined the complete amino acid sequence of Mirabilis antiviral protein (MAP). MAP is composed of 250 amino acids having a combined molecular weight of 27,833 and contains 23 lysine residues and 7 arginine residues. The amino acid sequence of MAP has 24% homology with the Ricin D-A chain. To carry out systematic structure-function studies of MAP, we have accomplished the total synthesis of its gene. We designed a synthetic MAP gene containing 12 unique restriction sites that were on the average 65 base pairs apart. Thirty synthetic oligonucleotides were enzymatically joined to form DNA duplexes. These were strategically synthesized to have EcoRI and HindIII cohesive ends and were cloned in pUC19. Nine blocks of the synthetic fragments were assembled in pUC19 to form the MAP gene consisting of 759 base pairs. The correctness of the connecting reactions was confirmed by step-wise sequencing of each assembled fragment as well as the total gene. When expressed under control of the tac promoter in Escherichia coli, the synthetic gene gave a protein similar to the native MAP. This was confirmed by an enzyme-linked immunosorbent assay and Western blotting analysis.

Amino Acid Sequence↗
PubMed1989

Involvement of antizyme in stabilization of ornithine decarboxylase caused by inhibitors of polyamine synthesis.

Contrary to previous findings, ornithine decarboxylase (ODC) was stabilized by treatment of cells with DL-alpha-difluoromethylornithine, an enzyme-activated irreversible inhibitor of ODC. Both this inhibitor and cyclohexylamine, a spermidine synthase inhibitor known to stabilize ODC, caused decreases in the antizyme/ODC ratio by increasing ODC content and conversely decreasing antizyme content. The relationship between cellular polyamine levels and antizyme content indicated that spermidine is the most important polyamine for antizyme induction. These results suggest that antizyme is involved in the mechanism underlying the stabilization of ODC by inhibitors of polyamine synthesis and support the hypothesis that cellular polyamines regulate ODC degradation via antizyme.

Animals↗
PubMed1989

Mechanism of reversion of Rous sarcoma virus transformation by herbimycin A: reduction of total phosphotyrosine levels due to reduced kinase activity and increased turnover of p60v-src1.

We studied the mechanism of reversion of Rous sarcoma virus (RSV)-transformation by herbimycin A in a temperature-sensitive RSV-infected NRK cell line. Herbimycin reduced the total cellular phosphotyrosine level to 10% of the control value. Intracellular p60src kinase activity was reduced significantly within 3 h of herbimycin treatment, but recovered to approximately 50% of the control within 24 h, and the kinetics paralleled the decrease of the phosphorylation of a cellular target p36. Partial proteolytic phosphopeptide analysis of p60src revealed decreased phosphorylation of tyrosine 416 in the C-terminal half. Analysis of the steady state level of p60src indicated 30% decrease in src protein. Measurement of the rates of p60src synthesis and degradation showed that the decrease in the level was due to the accelerated degradation of src protein. Cycloheximide blocked this enhanced turnover of p60src, but did not block the herbimycin-induced inactivation of p60src kinase. Subcellular distribution and myristoylation of p60src protein were not altered. These results support the idea that RSV transformation is associated with elevated phosphotyrosine levels and indicate that inhibition of src kinase activity can reverse RSV-transformation by reducing cellular phosphotyrosine content.

Amino Acids↗
PubMed1989

Bioactivity of human growth hormone in urine from acromegalic patients.

Bioactivity of hGH in urine from five acromegalic patients was determined by Nb2 bioassay and IM-9 receptor modulation assay (RMA). Urine samples were concentrated by immunoadsorbent chromatography, dialysis and lyophilization. The ratio of the bioactivity by Im-9 RMA and the immunoactivity by RIA was between 0.81 and 1.24 (1.01 +/- 0.19, mean +/- SD). The ratio of the bioactivity by Nb2 bioassay and the immunoactivity ranged from 0.45 to 0.60 (1.37 +/- 0.85). Gel chromatography of hGH in urine samples measured by sensitive sandwich enzyme immunoassay showed that more than 97% of hGH activity was the 22K form. Urinary hGH from acromegalic patients was bioactive in Nb2 bioassay and IM-9 RMA and the bioactivity showed a close correlation with the immunoactivity. The major immunoactive form of hGH (22K) seems to correspond to the bioactivity.

Acromegaly↗
PubMed1989

Sandwich enzyme immunoassay for ornithine decarboxylase.

A sensitive enzyme immunoassay (EIA) was developed for the determination of ornithine decarboxylase (ODC, EC 4.1.1.17), in the range of 0.02-10 ng, using an affinity-purified anti-ODC-Fab'-peroxidase conjugate. The amount of ODC protein was determined in crude extracts from the kidney of testosterone-treated mice, regenerating rat liver and human thyroid carcinoma, with purified mouse kidney or rat liver enzyme as standard. In all these tissues, similar activity/protein ratios were found for ODC: 1.2 x 10(6)-1.9 x 10(6) nmol CO2/h/mg of ODC protein, which were roughly equivalent to the final specific activity of purified enzymes. ODC inactivated by alpha- difluoro-methylornithine (DFMO) could also be assayed with this method similarly to active ODC protein. However, ODC-antizyme complex gave a somewhat lower value than free ODC protein.

Animals↗
PubMed1989

Loss of heterozygosity at polymorphic chromosomal loci in patients with malignant melanoma.

One type of aberration of DNA found in human cancers is loss of heterozygosity at chromosomal loci. This loss suggests that inactivation of particular genes is involved in the genesis of cancer cells. We have analyzed tumor DNA and normal DNA from eight patients with malignant melanomas using 24 polymorphic DNA probes and detected loss of heterozygosity in three patients at five loci on four different chromosomes. These results indicate that the frequency of loss of heterozygosity at chromosomal loci is relatively high in malignant melanomas, but that the regions lost are not restricted to specific chromosomes.

Adult↗