Biomedical subjects

Y Murakami

Publications and source records attributed to Y Murakami.

At least 703 records · Page 39Linked to original sources

PubMed1991

Neuroimaging findings (ultrasonography, CT, MRI) in 3 infants with congenital rubella syndrome.

Neuroimaging observations of three infants with congenital rubella syndrome are reported. We have observed congenital rubella syndrome lesions in the subependymal area, the basal ganglia and the deep white matter. Cranial ultrasonography defines subependymal cysts, calcification and possible vascular changes in the basal ganglia while MRI is the most sensitive to minor atrophic changes and white matter lesions. Although CT defines calcification, it is less sensitive than MRI to white matter changes and does not demonstrate subependymal cysts.

Female↗

PubMed1991

Multiple coronary stenoses of unknown etiology.

The case of a 13-year-old girl with multiple coronary stenoses and abundant collaterals, but no risk factors, is described. She was not suspected of having ischemic heart disease until an abnormal electrocardiographic pattern was detected during a routine examination in school. All children with electrocardiographic abnormality should be carefully examined, even though they have neither symptoms nor coronary risk factors.

Adolescent↗

PubMed1991

Multiple floppy valves with all cardiac valves prolapsing: clinical course and treatment.

Two cases with prolapse of all four cardiac valves are described and compared with two similar ones previously reported. The severity and progression of regurgitation of each of the valves differed by case, despite having similar echocardiographic findings consistent with the diagnosis of multiple floppy valves. Two of the four patients had their aortic valve replaced because of severe regurgitation: the excised valves revealed myxomatous degeneration. None of the patients had any stigmata of Marfan or Ehlers-Danlos syndrome, except for the presence of hyperextensive joints. There may be an unknown collagen disorder that caused floppiness in all the valves.

Adolescent↗

PubMed1991

The influence of clinical use of antibiotics and the sensitivity of strains isolated from postoperative infections--a comparison of nosocomial pathogens with strains isolated from the bacterial flora of patients.

In the present study, we investigated how the recent clinical use of antibiotics have altered the antibiotic susceptibility of strains isolated from postoperative infections, especially Gram-negative rods. For Pseudomonas aeruginosa, serogroup E strains accounted for about 20 per cent of postoperative infections, but were unable to be isolated from either the feces of patients on admission or from the appendix contents of patients with appendicitis. It therefore appeared that serogroup E strains were responsible for the nosocomial infections in our department. The strains of methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa serogroup E, which we assumed to be nosocomial pathogens, acquired a high level of resistance to antibiotics soon after third-generation cephems became widely used. On the other hand, the antibiotic susceptibility of Enterobacter cloacae, Citrobacter freundii, and the serogroups of Pseudomonas aeruginosa other than E, which were considered to originate from the bacterial flora of patients, did not vary throughout the several years of the study period.

Bacteria↗

PubMed1991

Platelet activating factor induced respiratory mucosal damage.

Human sinus mucosal specimens from eight normal individuals were exposed to platelet activating factor (PAF) at concentrations ranging from 10(-6) M to 10(-11) M in a humidified CO2 chamber at 37 degrees C. The mucosal surface of the specimens was recorded on video tapes and magnified 2,500 times on a 19-inch television (TV) monitor. Ciliary activity of each ciliated cell was photoelectrically measured on the TV monitor in real time. PAF induced mucosal damage which resulted in a coarse profile including ciliostasis and exfoliation of epithelial cells. The length of the incubation period in which the initial coarse profile occurred on the mucosal surface inversely correlated with the concentration of exposed PAF ranging from 10(-6) M to 10(-10) M with r = -0.712 (p less than 2 x 10(-4)). Both the control medium and 10(-8) M lysoPAF showed no effect on ciliary activity or mucosal surface alteration even after 24 hr of exposure. Significant ciliary inhibition was noted after 6 hr of exposure to PAF at concentrations of 10(-8) M and 10(-10) M (p less than 0.05). After 10 hr of exposure, significant ciliary inhibition (p less than 0.01) was noted at all concentrations. Inhibition occurred in a time- and dose-dependent manner. The length of the incubation period in which initial ciliostatis occurred and the level of PAF concentration showed an inverse correlation with r = -0.918 (p less than 10(-6)). These results indicate that PAF is cytotoxic to human respiratory mucosa.

Cilia↗

PubMed1991

Toxin involvement in methicillin-resistant Staphylococcus aureus enteritis in gastroenterological surgery.

The authors investigated the production of toxic shock syndrome toxin-1 (TSST-1) and staphylococcal enterotoxins (SE) by Methicillin-resistant Staphylococcus aureus (MRSA) isolates to clarify the pathogenesis of postoperative MRSA enteritis in patients undergoing gastroenterological surgery. Regarding the percentage of TSST-1 producing strains, there was a significant difference between type II MRSA strains (68.8%) and type IV MRSA strains (4.2%). Among type II strains, all those producing staphylococcal entorotoxin (SE) type C (SEC) also produced TSST-1, although other strains that produced SEB without TSST-1 were commonly isolated. Strains producing SEA were potent producers of SE which was considered to be responsible for enteritis. Therefore, we hypothesized that the strains which produced both SEA and SEC tended to cause enteritis associated with TSS-like symptoms owing to the high titer of these toxins.

Bacterial Toxins↗

PubMed1991

Induction of hsp 72/73 by herbimycin A, an inhibitor of transformation by tyrosine kinase oncogenes.

Herbimycin A, which has been known to inactivate and degrade p60v-src tyrosine kinase, induced an elevated synthesis of a protein with a molecular size of 70 kDa in A431 human epidermoid carcinoma cells. This protein showed the same migration distance on SDS-polyacrylamide gel electrophoresis as that of the protein induced in the cells by heat shock treatment, and this 70-kDa protein was identified as a member of the heat shock protein 70 family (hsp70) through immunoprecipitation with anti-hsp72/73 antibody and partial digestion with V8 protease. The induced level of the 70-kDa protein was dependent on the length of period and the concentration of herbimycin A treatment. Cellular fractionation and indirect immunofluorescence analyses revealed that the 70-kDa protein induced by herbimycin A was localized in the cytoplasm, in contrast to the nuclear distribution of hsp70 induced by heat treatment. Induction of hsp70 by herbimycin A was also observed in several other cells, including HeLa S3 cells, chicken embryo fibroblasts, NIH3T3 cells, and Rous sarcoma virus-transformed NIH3T3 cells.

Antibiotics, Antineoplastic↗

PubMed1991

Evaluation of glycoprotein gII ISCOMs subunit vaccine for pseudorabies in pig.

One of the pseudorabies virus glycoproteins, gII, was integrated into Quil A matrix and formed an antigenic presentation structure known as immunostimulating complexes (ISCOMs). The gII ISCOMs protected mice from a lethal infection of pseudorabies virus (PrV). Subsequently, the efficacy of gII ISCOMs as a vaccine was evaluated in pigs, a natural host species of PrV. Immunization of pigs with gII ISCOMs protected them from PrV-induced acute symptoms and death. The serum obtained from immunized pigs was clearly discriminated from that of infected pigs by immunoprecipitation. The data indicated that the ISCOM technique was useful in PrV subunit vaccine preparation and demonstrated the importance of glycoprotein gII as a component of PrV vaccine.

Animals↗

PubMed1991

Pharmacological properties of YM-21095, a potent and highly specific renin inhibitor.

A novel renin inhibitor, YM-21095 [2RS), (3S)-3-[N alpha-[1,4-dioxo-4-morpholino-2-(1-naphthylmethyl)-buthyl]-L- histidil-amino]-4-cyclohexyl-1-[(1-methyl-5-tetrazolyl)thio]-2-but anol), has been synthesized in our laboratories. The aim of this study was to evaluate the pharmacological properties of YM-21095 in in vitro and in vivo experiments. YM-21095 inhibited human renin with an IC50 value of 4.7 x 10(-10) mol/L. YM-21095 was also a potent inhibitor against squirrel monkey renin, but less effective against renins from dog, rabbit, and rat. The effect of YM-21095 is highly specific for renin, since it did not inhibit cathepsin D, pepsin, or angiotensin converting enzyme up to a concentration of 10(-4) mol/L. YM-21095 was resistant to proteolytic actions of the enzymes (pepsin, chymotrypsin, trypsin) and squirrel monkey tissue homogenates (liver, kidney, small intestine). Intravenous infusion of YM-21095 (0.1 to 100 micrograms/kg/min) decreased mean blood pressure and inhibited plasma renin activity in a dose-dependent manner with no effect on heart rate in anesthetized sodium-depleted and sodium-replete squirrel monkeys. The hypotensive effect of YM-21095 in sodium-depleted squirrel monkeys was about ten times as potent as that in sodium-replete squirrel monkeys. Oral administration of YM-21095 to conscious sodium-depleted squirrel monkeys produced dose-related decreases of systolic blood pressure. We conclude that YM-21095 is a potent and highly specific inhibitor of primate renin and produces a blood pressure lowering effect.

Administration, Oral↗

PubMed1991

Ornithine decarboxylase induction in partially hepatectomized rat liver and modes of its stimulation by glucagon and insulin.

Hepatic ornithine decarboxylase (ODC) activity increases after partial hepatectomy and this activity is further stimulated by pharmacologic doses of glucagon and insulin. We now present data suggesting that glucagon and insulin stimulate ODC activity by distinct mechanisms. ODC activity increased progressively after partial hepatectomy and reached an initial peak at 4 h. Activity decreased to 50% of its peak value at 6 and 8 h and then rose progressively to a maximum at 12 h. Enzymatic activity was well correlated with the amount of hepatic immunoreactive ODC protein, thus suggesting that increased enzyme activity was due to increased amount of enzyme protein. Hepatic ODC mRNA increased gradually and continuously, reaching the maximal value by 12 h. In rats receiving glucagon after partial hepatectomy, ODC mRNA increased significantly by 2 h and enzyme immunoreactive protein and activity by 2 to 4 h as compared to controls. In contrast, insulin administration only induced a significant increase in enzyme immunoreactive protein and activity 10 to 12 h after partial hepatectomy. No significant changes in ODC mRNA level were observed. Our data suggest that the regulation mechanism of ODC induction following partial hepatectomy differs depending on the time after operation. Our data also suggest that while glucagon appears to regulate ODC activity by a transcriptional mechanism, insulin appears to operate at a post-transcriptional level.

Animals↗

PubMed1991

Factor XIIIa expression in pseudo-Kaposi sarcoma.

A 39-year-old man had pseudo-Kaposi sarcoma on his left foot. A biopsy specimen obtained from a cutaneous lesion showed increased numbers of vascular spaces, proliferation of fibroblast-like spindle cells, and deposition of hemosiderin in the dermis. Immunohistochemically, proliferative fibroblast-like spindle cells around the vessels were positive for anti-factor XIIIa antibody. Excessive heat radiation was detected from the skin lesions by thermography.

Adult↗

PubMed1991

Genetic alteration of p53 in some patients with adult T-cell leukemia.

Abnormalities of p53 mRNA in adult T-cell leukemia (ATL) were analyzed using reverse transcription-polymerase chain reaction-single strand conformation polymorphism analysis. Mutations were present in two of 12 ATL patients studied, but not in 3 cell lines immortalized by human T cell leukemia virus type 1 (HTLV-1) infection in vitro. Direct sequencing analysis of the p53 gene from these two patients revealed missense point mutations at codon 153 (arginine to histidine) or codon 220 (cysteine to tyrosine), respectively. Immunohistochemical analysis revealed the elevated expression of p53 proteins in ATL cells from a patient carrying the mutated p53 gene at codon 158. Neither gross rearrangement of p53 gene nor abnormal size of mRNA for the gene was demonstrated by Southern or Northern blot analyses. Thus, there is a mutated p53 in some patients with ATL. The involvement of abnormalities in some suppressor oncogenes may play a role in the development of ATL.

Base Sequence↗

PubMed1991

Purification and properties of neuraminidase from the culture medium of Bacteroides loescheii.

Neuraminidase was purified from the culture medium of Bacteroides loescheii ATCC 15930 by ultrafiltration followed by a DEAE-Sephacel anion exchange chromatography, fast-protein liquid chromatography using Mono P column and high-performance liquid chromatography using a Shim-pack Diol-300 column. The molecular weight of the purified enzyme was measured to be approximately 87 kDa and the optimal pH was at 4.8. Although the enzyme was able to hydrolyze the substrates with alpha,2-3, alpha,2-6, and alpha,2-8 linkages of N-acetylneuraminic acid, the rate of hydrolysis of N-acetylneuraminosyl-alpha,2-3-lactose was greater than that of the alpha,2-6-isomer.

Bacteroides↗

PubMed1991

Bacteroides (Porphyromonas) gingivalis fimbriae activate mouse peritoneal macrophages and induce gene expression and production of interleukin-1.

The purpose of this study was to examine whether Bacteroides (Porphyromonas) gingivalis fimbriae, an important structure involved in attachment of the bacteria to periodontal tissues, activate macrophages and subsequently induce gene expression and production of interleukin-1 (IL-1) in the cells. The fimbriae increased glucose consumption and lysozyme activity in BALB/c macrophages, both criteria of macrophage activation of peritoneal macrophages, in a dose-dependent fashion. A marked increase in the mRNA level of the c-myc gene, an oncogene, in the cells was observed after a 1-h treatment with the fimbriae, and the level decreased rapidly after 3 h. The fimbriae (4 micrograms of protein per ml) markedly induced IL-1 alpha and IL-1 beta gene expression in the cells and IL-1 production. The expression of IL-1 alpha and IL-1 beta genes measured in terms of specific mRNA increased 1 h after the start of treatment and peaked at 6 h. Such increased expression of IL-1 beta was also observed in C3H/HeJ mice, a lipopolysaccharide low-responder strain. The fimbriae stimulated transcriptional activity of IL-1 beta in the cells, but not that of IL-1 alpha. We also observed that fimbriae-induced IL-1 gene expression was not regulated by endogenous prostaglandin triggered by the fimbriae. Therefore, these observations suggest that B. gingivalis fimbriae may be involved in the pathogenesis of adult periodontal disease via triggering of IL-1 production by monocytes/macrophages in periodontal diseases.

Animals↗

PubMed1991

Inhibitory effects of human salivary histatins and lysozyme on coaggregation between Porphyromonas gingivalis and Streptococcus mitis.

The effects of histatins on coaggregation between Porphyromonas gingivalis 381 and Streptococcus mitis ATCC 9811 were investigated by using a turbidimetric assay. The coaggregation activity was significantly inhibited by histatins 5 and 8 and strongly by lysozyme. Tritium-labeled histatin 8 bound to P. gingivalis cells but not to S. mitis cells.

Amino Acid Sequence↗

PubMed1991

Mouse DNA primase plays the principal role in determination of permissiveness for polyomavirus DNA replication.

We have investigated the species-specific replication of polyomavirus DNA in the cell-free system that was established previously (Y. Murakami, T. Eki, M. Yamada, C. Prives, and J. Hurwitz, Proc. Natl. Acad. Sci. USA 83:6347-6351, 1986). Extracts from various species of cells supported polyomavirus DNA replication in a species-specific manner that was consistent with the host range specificity of polyomavirus; extracts prepared from mouse and hamster cells were active, whereas extracts prepared from human, monkey, and insect cells were inactive. The addition of DNA polymerase alpha-primase purified from mouse cells induced the replication of polyomavirus DNA in a cell-free system containing polyomavirus large tumor antigen and nonpermissive cell extracts, such as human and insect cell extracts. Isolated mouse DNA primase alone also induced polyomavirus DNA replication in human cell extracts but not in insect cell extracts, indicating that mouse DNA primase plays the principal role in determining permissiveness for polyomavirus DNA replication.

Animals↗

PubMed1991

Cholinergic modulation of growth hormone secretion induced by galanin in rats.

The effects of cholinergic modulation by hexamethonium (HEX), tetraethylammonium (TEA), pirenzepine (PIR) and neostigmine on growth hormone (GH) secretion induced by galanin (GAL) were investigated in awake, freely moving male rats. Intracerebroventricular (i.c.v.) injection of GAL (0.6 nmol) caused a marked increase in plasma GH levels. Pretreatment with HEX (3 or 15 mg/kg BW), TEA (15 mg/kg BW) or PIR (0.5 mg/kg BW) significantly reduced the GAL-induced GH secretion. Pretreatment of animals with neostigmine (0.05 mg/kg BW) or with a specific antisomatostatin antiserum (10 microliters of 1:10 diluted with saline, i.c.v.) reversed the inhibition of GAL-induced GH secretion by HEX. These findings suggest that both nicotinic and muscarinic cholinergic mechanisms interact with the galanin-induced GH secretion by modulating hypothalamic somatostatin release.

Animals↗

PubMed1991

[Mechanism of protective effects of ouren-gedoku-to and san'ou-syashin-to on the gastric mucosa].

Ouren-Gedoku-To (OGT) and San'ou-Syashin-To (SST), traditional Chinese prescriptions, have been used to treat peptic ulcer. In order to elucidate the mechanism of the protective effects of OGT and SST on the gastric mucosa, we studied their effects on gastric mucosal lesions, ion permeability and prostaglandin synthesis using ulcer experimentally induced in rats by saturation with acidic test solution after taurocholate treatment. Both OGT and SST inhibited taurocholate-induced gastric mucosal lesions in a dose-related manner. These prescriptions dose-dependently inhibited not only the increase of hydrogen and sodium ion net fluxes but also possible hydrogen ion back diffusion into the gastric mucosa during saturation with acidic test solution. SST induced a significant increase in gastric mucosal prostaglandins synthesized from 14C labeled arachidonate. These results suggest that both OGT and SST by strengthening the gastric mucosal barrier demonstrate their protective effects on the gastric mucosa and that this effect of SST is attributable to the increased ability of the gastric mucosa to synthesize prostaglandin.

Animals↗