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Biomedical subjects

T Okabe

Publications and source records attributed to T Okabe.

At least 217 records · Page 12Linked to original sources
PubMed1993

Methods of evaluation of release of carbon dioxide from effervescent suppositories.

Two different test methods were studied for the evaluation of release profiles of carbon dioxide, CO2, from effervescent suppositories. Three lots of commercial suppositories containing sodium bicarbonate and anhydrous sodium dihydrogen phosphate were used. The volume of CO2 released from these suppositories in normal saline with or without polysorbate 80 as a medium was measured with a gas burette. In the measurement performed using the apparatus without stirring, method 1, only 60% of CO2 was released from the suppositories in the medium without polysorbate 80. In this measurement, a native release profile was detected because the medium was not stirred. In the case with stirring, however, method 2, 100% was released from those suppositories in the medium containing 1% polysorbate 80 with comparatively low standard deviations. These findings indicate that method 1 is most beneficial for a test comparing the effects of various factors such as additives and melting points on the release profiles of CO2 from the effervescent suppositories. However, this method is not practical for quality control of formulations because of the incomplete release of CO2; method 2, in contrast, is useful because of its complete release and low standard deviations. These results suggest that methods 1 and 2 for release tests of CO2 are most applicable to the early and late formulation studies of effervescent suppositories, respectively.

Carbon Dioxide↗
PubMed1993

Passive protection of mice against Actinobacillus pleuropneumoniae infection by monoclonal antibodies.

Mouse monoclonal antibodies (MAbs), Y-4b, F-6b and K-6a recognized as capsular antigens of A. pleuropneumoniae serotypes 1, 2 and 5, respectively, and MAb H-1b as lipopolysaccharide (LPS) of serotype 2 were produced. We examined the passive immunizing efficacy of these MAbs on A. pleuropneumoniae infection in C3H/HeJ mice. On the challenge infection of homologous serotype strains, they showed a sufficient protective effect in immunized mice. It was concluded that MAbs recognized as capsular antigen and LPS have a serotype-specific protective effect on A. pleuropneumoniae infection, suggesting the important role in preventing A. pleuropneumoniae infection.

Actinobacillus Infections↗
PubMed1993

Determining amalgam marginal quality: effect of occlusal surface condition.

Currently there is no "standard" finishing and polishing procedure for dental amalgam restorations. This investigation evaluated the effect of four different finishing techniques on the durability of dental amalgam restorations as determined by the marginal breakdown. Burnishing immediately before carving or as part of the condensation process seems to improve the carving characteristics of the amalgam.

Dental Alloys↗
PubMed1993

Compositions of surface layers formed on amalgams in air, water, and saline.

The surface layers formed on both a zinc-free and a zinc-containing dental amalgam after polishing and aging in air, water, or saline, were characterized using x-ray photoelectron spectroscopy (XPS) to determine the compositions of the surface layers which might govern the release of mercury from amalgam. The XPS data revealed that the formation of the surface layer on the zinc-containing amalgam was affected by the environment in which the amalgam was polished and aged, whereas that on the zinc-free amalgam was not affected. In addition, among the elements contained in amalgam, zinc was the most reactive with the environment, and was preferentially dissolved from amalgam into water or saline. Mercury atoms existed in the metallic state in the surface layer.

Air↗
PubMed1993

[Preventive chemotherapy after transurethral prostatectomy: a randomized study].

The usefulness of preventive chemotherapy was studied in transurethrally prostatectomized patients with no prior urinary tract infections. They were divided into two groups (A and B) randomized by the envelope method. A was administered intravenously piperacillin (PIPC) 2 g once after surgery, and twice on the following day. B was similarly administered PIPC intravenously, followed by oral administration of tosufloxacin tosilate (TFLX) 300 mg twice daily from the second to the fifth day. Of the total of 135 cases, 104, 45 in A and 59 in B, conformed to the patient standards established for analysis. Efficacy was assessed by the primary physician and also according to a unified standard in which the onset of a post-surgical infection and a bacteriuria of 10(4) or greater CFU/ml observed ten days after surgery were regarded as ineffective. An intergroup statistically significant difference was not observed in the efficacy rate assessed by the primary physician. However, according to the unified standard assessment, B showed a significantly higher efficacy rate (88.1%) than A (62.2%). The administration of TFLX following PIPC was useful. With an indwelling catheter, B exhibited a significantly greater efficacy rate when the retention period was four days or longer. The efficacy was greater in both groups if lavage was not performed, and this effect was greater in A. Consequently, the administration of TFLX was considered more useful for long-term indwelling catheter cases. Neither serious side effects, nor clinical test abnormalities were observed in this study.

Aged↗
PubMed1993

[A case of clear cell adenocarcinoma of the female urethra].

A 49-year-old female visited our hospital because of bloody discharge from the urethra. On examination, an elastic-soft mass was palpable beneath the anterior vaginal wall. The vaginal mucosa was intact. Cystourethroscopy demonstrated neither tumor nor diverticular orifice. Pathological specimen obtained by needle biopsy revealed clear cell adenocarcinoma. The patient underwent anterior pelvic exenteration and modified Kock pouch urinary diversion. The microscopic appearance suggested that the tumor arose from the paraurethral duct. Stains for prostatic specific antigen and prostate specific acid phosphatase were negative. Forty cases of clear cell adenocarcinoma of the female urethra reported in the literature were reviewed.

Adenocarcinoma, Clear Cell↗
PubMed1993

Butyrolactone I, a selective inhibitor of cdk2 and cdc2 kinase.

We screened cdc2 kinase inhibitors from cultured mediums of micro organisms using purified mouse cyclin B-cdc2 kinase and a specific substrate peptide for cdc2 kinase. A selective inhibitor of cdc2 kinase was isolated from the cultured medium of Aspergillus species F-25799, and identified as butyrolactone I. Butyrolactone I inhibited cdc2 and cdk2 kinases but it had little effect on mitogen-activated protein kinase, protein kinase C, cyclic-AMP dependent kinase, casein kinase II, casein kinase I or epidermal growth factor-receptor tyrosine kinase. Its inhibitory effect was found to be due to competition with ATP. Butyrolactone I selectively inhibited the H1 histone phosphorylation in nuclear extracts. It also inhibited the phosphorylation of the product of retinoblastoma susceptibility gene in nuclear extracts and intact cells. Thus butyrolactone I should be very useful for elucidating the function of cdc2 and cdk2 kinases in cell cycle regulation.

4-Butyrolactone↗
PubMed1992

Pyrogenic action of endothelin in conscious rabbit.

Injection of 0.3 nmol/kg endothelin(ET)-1 into the ear vein of conscious rabbits induced a significant increase in body temperature. ETB receptor specific agonist, namely 4-Ala-ET-1, also caused an elevation of the body temperature in a dose-dependent manner by injection into the ear vein of rabbit. These results suggest that ET play important roles in regulation of body temperature through selective stimulation of ETB receptor.

Analysis of Variance↗
PubMed1992

Calmodulin is involved in catecholamine secretion from digitonin-permeabilized bovine adrenal medullary chromaffin cells.

The role of calmodulin in exocytotic secretion was studied using digitonin-permeabilized bovine adrenal medullary chromaffin cells. Addition of calmodulin to the permeabilized cells increased Ca(2+)-dependent norepinephrine release in a dose-dependent manner. Unlike calmodulin, addition of caldesmon, actin or bovine serum albumin did not increase the release. Calmodulin increased the release at Ca2+ concentrations of more than 10(-6) M and its effect increased with increase in Mg2+ concentration. Th release of norepinephrine enhanced by calmodulin was inhibited by tetanus toxin, which specifically inhibits exocytotic secretion. These results indicate directly that calmodulin plays an important role in exocytotic secretion from chromaffin cells.

Actins↗
PubMed1992

Characterization of immunoreactive endothelin in human urine.

We developed three antibodies, specific and sensitive to endothelin-1 (ET-1), and established two sandwich and three competitive enzyme immunoassays (EIAs). By using these EIAs, large immunoreactive ET (IR-ET) of molecular weight 10 k Da was identified as a main component of IR-ETs in human urine. This large IR-ET, which reacted with two antibodies specific for N-terminal region of ET-1 but not with the antibody against C-terminal peptide of ET-1, was partially purified by six-step procedure and examined by Western blotting after SDS polyacrylamide gel electrophoresis. The large IR-ET was detected as a single band at molecular weight of 10 k Da both in reduced and non-reduced conditions. From these results, the large IR-ET was thought to consist of a single polypeptide chain and possess the steric restricted N-terminal region of ET-1.

Amino Acid Sequence↗
PubMed1992

Pre-B lymphocyte-specific transcriptional control of the mouse VpreB gene.

The VpreB genes, which encode surrogate immunoglobulin light chain molecules, are expressed as RNA almost exclusively in pre-B cells. We have investigated the transcriptional control mechanisms which are responsible for the pre-B cell-specific RNA expression of the mouse VpreB1 and VpreB2 genes. Nuclear run-on analyses demonstrate that the pre-B cell-specific expression of both VpreB genes is controlled primarily at the level of initiation of transcription. S1 nuclease protection-mapping defined two or three major start sites of transcription for the VpreB genes. To find a promoter and other potential cis-acting regulatory elements, a 700-bp fragment 5' of the transcription start sites of the VpreB1 gene was used in gene transfer experiments and found to act as a promoter in pre-B lymphocytes. Deletion experiments showed that 191 bp upstream of the most 5' transcription start site is required for the pre-B cell promoter activity. DNA sequence analysis of the 5' region of the mouse VpreB1, VpreB2 and human VpreB genes reveal that this region of approximately 200 bp is strongly conserved. This 200-bp promoter region contains several conserved nucleotide sequence motifs which may act to mediate the pre-B cell-specific transcription of the VpreB genes.

Animals↗
PubMed1992

A pre-B- and B cell-specific DNA-binding protein, EBB-1, which binds to the promoter of the VpreB1 gene.

The VpreB1 protein is thought to be expressed on the surface of pre-B cells in association with lambda 5 and mu heavy chain, and to play an important role on B cell differentiation. The expression of VpreB1 and lambda 5 is pre-B cell specific, and regulated at the initiation of transcription. We have identified at least two sequence-specific DNA-binding proteins which bind to the region -191 to -74 of the promoter of the mouse VpreB1 gene. These DNA-binding proteins also bind to the promoter of the mouse lambda 5 gene. One of the two DNA-binding proteins, called EBB-1, is restricted to pre-B and B cells, but not detected in plasma cells, T cells and cells of other lineages. Transient transfection analysis of reporter constructs revealed that the binding sites of these proteins play a significant role in the activity of the promoter, especially the binding site of EBB-1. Taken together these results suggest that EBB-1 might be one of the crucial factors which regulates a series of intracellular events in B cell differentiation.

Animals↗
PubMed1992

The characteristics of blood-brain barrier in three different conditions--infarction, selective neuronal death and selective loss of presynaptic terminals--following cerebral ischemia.

We investigated the extravasation of serum albumin using immunohistochemistry in three different conditions, i.e., infarction, selective neuronal death and selective loss of presynaptic terminals following cerebral ischemia in gerbils. In selective neuronal death, which is typically found in the CA1 neurons of the hippocampus after 5-min bilateral cerebral ischemia, selective damage of postsynaptic components with intact presynaptic sites was demonstrated by immunohistochemical examination for microtubule-associated protein 2 and synapsin I, and albumin extravasation did not become apparent before postsynaptic structures were destroyed. In cerebral infarction, which was consistently observed in the thalamus after 15-min forebrain ischemia, massive albumin extravasation was visible early after ischemia due probably to the ischemic endothelial necrosis. In selective loss of presynaptic terminals, which was detected at the molecular layer of the dentate gyrus in the contralateral, nonischemic hippocampus after unilateral cerebral ischemia, immunoreaction for albumin was not visualized. Since endothelium and glial cells were intact in morphological aspects in selective damage of both pre- and postsynaptic sites, it was thought that extravasation was facilitated by the stimulation of endothelial cells and glial cells with unknown factors that were induced by the destruction of post- but not presynaptic elements.

Albumins↗
PubMed1992

Inhibition of neuromuscular transmission in isolated mouse phrenic nerve-diaphragm by the enterotoxin of Clostridium perfringens type A.

The enterotoxin of Clostridium perfringens type A, a channel forming protein toxin, inhibited neuromuscular transmission under conditions of low calcium. Twitch tension of isolated phrenic nerve-diaphragm preparations elicited by electrical stimulations to the phrenic nerve was recorded isometrically, and the preparations were exposed to the purified enterotoxin. In Krebs solution containing 0.5 mM calcium, the enterotoxin (20 micrograms/ml) reduced within 10 min the amplitude of the twitch tension to 34 +/- 7% (mean +/- S.D., n = 11) of that recorded before the treatment. The effects of the enterotoxin on the twitch tension were irreversible and proceeded independently of stimulation. The reduction of the twitch tension by the enterotoxin was apparent in Krebs solution containing less than 0.6 mM calcium and the degree of reduction was inversely related to the concentration of calcium. The reduction of the twitch tension by the enterotoxin was also dependent on temperature and concentration of the toxin. At temperatures below 20 degrees C, no obvious reduction of twitch tension was observed with 20 micrograms/ml of the enterotoxin. Enterotoxin at a concentration of 0.4 micrograms/ml caused 16 +/- 2% (mean +/- S.D., n = 4) reduction of twitch tension, and the degree of the reduction in twitch tension increased with toxin concentration, reaching a plateau of 65 +/- 4% (mean +/- S.D., n = 7) at 6.5 micrograms/ml of the enterotoxin. The effects of the enterotoxin were antagonized by 2 microM physostigmine. Unlike curare, pretreatment of the preparation with enterotoxin did not antagonize the neuromuscular block by decamethonium. Neither the tension of muscular twitch elicited by direct electrical stimulation to the muscle nor the resting membrane potentials of muscle fibers recorded intracellularly were affected by the enterotoxin. The enterotoxin (2.2 micrograms/ml) reduced the frequency, but not mean amplitude or amplitude distribution, of miniature end-plate potentials, from 0.91 +/- 0.07/sec to 0.72 +/- 0.07 (mean +/- S.E., n = 5). The results suggest that the enterotoxin will provide a novel tool for the studies on the mechanism of the neuromuscular transmission because of the unique characteristics of the inhibition and of the known mechanism of its action on the cell membrane.

Animals↗
PubMed1992

Quantitation of total mercury vapor released during dental procedures.

An in vitro method is described in which measurements were made of the total amount of mercury vapor released from three types of amalgam during routine dental procedures. It was found that the greatest amount of mercury was released during dry polishing of one amalgam (44 micrograms). Removal of amalgam from a Class I cavity under water spray and high volume evacuation also generated large amounts of mercury as expected (15-20 micrograms). However, under the more clinically relevant conditions of extending evacuation for one minute to remove residual amalgam and mercury after cutting, this value was reduced by approximately 90%. The total amount of mercury generated during placement (6-8 micrograms), wet polishing (2-4 micrograms) and trituration (1-2 micrograms) were also measured. The study showed that dental procedures associated with amalgam do potentially expose the patient and operator to mercury vapor. However, the total amount of mercury released during any procedure was far below the total exposure level calculated from the daily threshold limits established by regulatory agencies for occupational exposure.

Air Pollutants, Occupational↗
PubMed1992

User requirements and standards for PACS. 2nd Japan-Nordic PACS Symposium.

PACS has been regarded as a system which will bring a new era to image handling, radiology departments and its services to other departments of the hospital. However, many recently held international conferences indicate that a worldwide consensus on 'what is PACS, why is PACS needed and who is PACS for' has not been established. Although the actual PACS implementation will vary among the countries and according to each situation, a worldwide consensus of PACS should be possible. This would help those involved to speed up the implementation of PACS. It is suggested that this consensus needs to be developed by convergence of three points of view; the availability, maturity and cost of the technologies on which PACS is built, the user requirements for PACS and standardization in PACS. These themes were the topics of the 2nd Japan-Nordic PACS Symposium which was arranged in Tampere, Finland, June 9-11th 1991. A summary of the papers and discussions of the symposium is produced in this paper.

Cost-Benefit Analysis↗