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Biomedical subjects

H Aoki

Publications and source records attributed to H Aoki.

At least 487 records · Page 27Linked to original sources
PubMed1986

Platelet activating factor (PAF) involvement in endotoxin-induced thrombocytopenia in rabbits: studies with FR-900452, a specific inhibitor of PAF.

PAF (1 ug/kg) injected intravenously (i.v.) into anesthetized rabbits resulted in marked loss of circulating platelets and leukocytes. Administration of FR-900452 1-methyl-3-(1-(5-methylthiomethyl-6-oxo-3-(2-oxo-3-cyclopenten-1-y lidene)- 2-piperazinyl) ethyl)-2-indolinone, a specific PAF inhibitor, at a dose of 10 mg/kg i.v. with 10 min prior to the PAF injection significantly prevented both changes. On the other hand, PAF has been considered as a mediator of endotoxin shock. Therefore, in order to determine whether endogenous PAF contributes to the occurrence of thrombocytopenia or leukopenia in endotoxin shock, we assessed the effect of FR-900452 on the thrombocytopenia and the leukopenia following bolus i.v. injection of E.coli endotoxin (0.03 mg/kg) in rabbits. As a result, pretreatment with the compound (10 mg/kg, i.v.) significantly reduced the thrombocytopenia at 60 and 180 min after the endotoxin injection. In contrast, FR-900452 did not reduced the leukopenia at any time of after endotoxin. These results indicate that PAF might be involved in the occurrence of thrombocytopenia in rabbit endotoxemia and the contribution of PAF to the leukopenia is much less extent than that to the thrombocytopenia.

Animals↗
PubMed1986

Growing skull fracture in childhood. A recurrent case treated by shunt operation.

The authors report a case of growing skull fracture in which watertight dural closure was difficult at the first operation because a dural defect extended deep into the middle fossa. Bulging of the cranioplasty site occurred 2 months later. In the second operation, instead of reinforcement of the dura mater, a shunt operation was performed to decompress the cyst and the locally dilated ventricle, which was thought to contribute to the intracranial expansive forces. The bulging did not recur. In the treatment of growing skull fracture, a shunt operation should be considered when watertight closure of the dural defect cannot be achieved and in case of recurrence after failure of the first operation.

Cerebrospinal Fluid Shunts↗
PubMed1986

Tissue reactions to calcined bone graft.

Calcined bone blocks made by heating raw bovine bone at 1200 degrees C were implanted into defects in canine femoral condyles. X-ray diffraction patterns showed that the calcined bone was well-crystallized hydroxyapatite. Rapid, good new bone growth was observed around the calcined bone which was gradually absorbed along its surface and also by the Haversian canals.

Animals↗
PubMed1986

Human penile hemodynamics studied by a polarographic method.

Observations of the tissue oxygen tension alteration were made using an open tip type oxygen electrode polarographic method as an index of blood flow change in the penile skin, corpus cavernosum and thigh skin of 16 males aged 20-26 years (average age: 20.5 years). In another five males aged 18-21 (average age: 19.8 years) the relationship between corpus cavernosum tissue oxygen tension alteration and penile circumference change in the erection process was observed. This relation was obtained in the penile circulation model, and penile hemodynamics were ascertained. In the flaccid penis the corpus cavernosum contains low-oxygen blood and there is a blockade at the vascular tree in the corpus cavernosum. In the tumescence phase the blood flow of the corpus cavernosum increased suddenly by the relief of cavernosum vascular blockade. During the penile tumescence phase the increased inflow and outflow persisted in corpus cavernosum, and in penile skin the blood also increased initially, but gradually decreased as penile circumference increased. After erection was attained it is thought that resistance to inflow occurred by outflow pathway contraction. In the detumescence phase, a decrease of inflow and a concomitant increase of outflow occurred and the reopening of outflow is thought to be necessary for prompt penile detumescence.

Adult↗
PubMed1986

Isolation and characterization of the sucrose 6-phosphate hydrolase gene from Streptococcus mutans.

The Streptococcus mutans GS-5 gene, scrB, coding for sucrose 6-phosphate hydrolase activity has been cloned into Escherichia coli utilizing the bacteriophage replacement vector lambda L47.1. DNA sequences containing the gene were initially subcloned into the moderate-copy-number plasmid vector pLG339 to yield active subclones. However, due to the instability of the resultant chimeric plasmids, the gene was subsequently subcloned into the low-copy-number vector pOU61 to yield the stable hybrid plasmid pMH613. Both plasmids contain a 6.6-kilobase EcoRI fragment from strain GS-5 and express both hydrolase and sucrase activities. The relative position of the gene in the insert has been determined after Tn5 mutagenesis and deletion analysis. The cloned enzyme was purified to near homogeneity after gel filtration and anion-exchange chromatography, chromatofocusing, and preparative polyacrylamide gel electrophoresis. The purified enzyme displayed a molecular mass of 58 kilodaltons, which is significantly higher than the 48-kilodalton enzyme previously purified from S. mutans GS-5. These results suggest that processing of the hydrolase occurs in S. mutans.

Cloning, Molecular↗
PubMed1986

Cloning of a Streptococcus mutans glucosyltransferase gene coding for insoluble glucan synthesis.

The gtfB gene coding for a glucosyltransferase (GTF) activity of Streptococcus mutans GS-5 was isolated on a 15.4-kilobase DNA fragment by using a lambda L47.1 gene library. The activity was catalyzed by gene products of 150 and 145 kilodaltons which reacted with antibodies directed against both soluble and insoluble glucan-synthesizing GTFs. The enzyme present in crude Escherichia coli extracts synthesized both soluble and insoluble glucans. The enzyme was partially purified from lysates of the lambda DS-76 clone and synthesized both types of glucans in a primer-independent fashion. In addition, the purified enzyme exhibited a pI of approximately 5.0. Southern blot analysis indicated that the cloned GTF gene represented a contiguous nucleotide sequence on the strain GS-5 chromosome. Furthermore, evidence for the existence of a distinct gene sharing partial homology with gtfB was also obtained. The gtfB gene was subcloned into plasmid pACYC184 into E. coli and exhibited GTF activity when carried on GS-5 inserts as small as 5 kilobases. The approximate location of the GTF promoter and the direction of gene transcription were also determined. The cloned enzyme was not secreted through the cytoplasmic membrane of E. coli, since most of the activity was found in the cytoplasm and, in lesser amounts, associated with the cytoplasmic membrane. The gtfB gene was insertionally inactivated by introducing a gene fragment coding for erythromycin resistance into the GTF coding region. After transformation of strain GS-5 with the altered gene, transformants defective in insoluble glucan synthesis were identified. These results indicate that the gtfB gene codes for a GTF involved in insoluble glucan synthesis in strain GS-5.

Base Sequence↗
PubMed1986

Pituitary dwarfism: CT evaluation of the pituitary gland.

The pituitary glands of 12 patients, aged 4-20 years, with pituitary dwarfism and of 15 age-matched control patients were evaluated with contrast-enhanced, high-resolution computed tomography (CT). In control patients, CT clearly demonstrated pituitary glands and stalks, 2.5-9.0 mm in height (average, 5.7 mm +/- 1.8). In the 12 patients with pituitary dwarfism, CT did not demonstrate the gland or stalk in four; CT faintly showed only the stalk in another four and showed a small gland (less than 2 mm in height) and a small to normal stalk in the remaining four. Eleven of the 12 patients had a birth history of breech presentation. Possible causes of pituitary dwarfism are discussed.

Adolescent↗