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Biomedical subjects

Y Ohashi

Publications and source records attributed to Y Ohashi.

At least 685 records · Page 38Linked to original sources
PubMed1983

Hanganutziu-Deicher heterophile antigen in human retinoblastoma cells.

We investigated the possible existence of Hanganutziu-Deicher antigen (HD antigen) on retinoblastoma cells by means of indirect membrane immunofluorescence and a complement-dependent antibody-mediated cytotoxicity test. We prepared antiserum in the chicken by immunization with purified equine hematoside highly specific to HD antigen. Three kinds of retinoblastoma cell lines, Y-79, WERI-Rb 1, and TOTL-1, showed positive membrane staining. Y-79 and TOTL-1 cells were also confirmed by the cytotoxicity test to possess HD antigen. Retinoblastoma cells freshly isolated from two patients had a positive membrane immunofluorescence. These results indicated that HD antigen was expressed in human retinoblastoma cells in vitro as well as in vivo.

Antigens, Heterophile↗
PubMed1983

Activation of DNA ligase by poly(ADP-ribose) in chromatin.

To elucidate the molecular mechanism by which poly(ADP-ribose) participates in DNA excision repair, we examined the effect of poly(ADP-ribose) on DNA ligase activity in DNA/histone and reconstituted chromatin systems. The ligase activity was markedly inhibited by histones; the inhibition varied depending on histone subfraction and DNA/histone ratio. Poly(ADP-ribose), either exogenous or synthesized in situ by poly(ADP-ribose) synthetase, reversed this inhibition by histone almost completely. This effect was specific for poly(ADP-ribose); polyanions such as mRNA, rRNAs, tRNA, and synthetic poly(A) were less effective or ineffective. The ligase activity with reconstituted chromatin as the substrate was about half of that with free DNA whereas the activities with these two substrates were almost the same in the presence of poly(ADP-ribose) synthesized in situ. The polymers synthesized under these conditions were exclusively bound to the synthetase. Together with our previous finding that the enzyme is the main acceptor of the polymer in DNA-damaged cells, these results suggest that poly(ADP-ribose) in the synthetase-bound form counteracts inhibition by histones and activates DNA ligase to rejoin DNA strands in polynucleosomal structures.

Animals↗
PubMed1983

Fibronectin promotes epithelial migration of cultured rabbit cornea in situ.

We investigated the effect of fibronectin on epithelial migration onto the stroma in cultured rabbit cornea. Rabbit plasma fibronectin was purified by affinity chromatography using gelatin-Sepharose 4B, and its purity was confirmed by SDS polyacrylamide slab gel electrophoresis. Antibody against rabbit plasma fibronectin raised in guinea pigs formed a single precipitin line against rabbit plasma and purified rabbit plasma fibronectin by Ouchterlony double diffusion test. When rabbit cornea was cut into small blocks and cultured in TCM-199 medium alone, corneal epithelial cells began to migrate on the cut edge of the corneal stroma. The addition of purified rabbit plasma fibronectin to the culture medium significantly enhanced epithelial migration. The degree of enhancement depended on the amount of fibronectin added. When guinea pig IgG anti-rabbit plasma fibronectin was added, epithelial migration was significantly inhibited when compared with that in control cultured corneal blocks. The results demonstrate that fibronectin promotes epithelial migration in the cornea and thus plays an important role in corneal wound healing.

Animals↗
PubMed1983

Reduced ciliary action in chronic sinusitis.

In chronic sinusitis, the disturbance of mucociliary transport explicitly represents the pathology of the mucous membrane. It was established by a photo-electric method that in this disease, mucociliary transport is disturbed as the result of not only change in secretory function but also a decrease in the frequency of ciliary beating. In the in vitro experiment using mucous membrane samples from 10 cases of chronic sinusitis, the frequency of ciliary beating was lowered slightly to about 409 +/- 84 beats per minute at 30 degrees C. In the most active phase of action, human cilia in sinusitis beat about 720 times per minute at 30 degrees C in vitro. The ciliary actions of the mucous membrane in human chronic sinusitis were classified into three types: 1) gathering type, 2) bifocal type, and 3) scattering type.

Animals↗
PubMed1983

Functional and morphological pathology of chronic sinusitis mucous membrane.

The previous paper (Part I) in our study described how a decrease in the frequency of ciliary beating was responsible for the deceleration of mucociliary transport in chronic sinusitis. In the present work, it was examined whether or not the reduction in ciliary beating frequency is associated with morphological changes in the mucosal epithelium. As a result, a very close correlation was found between them: the more severe the morphological changes, the more the beating frequency was reduced. The morphological changes of the mucosal epithelium in chronic sinusitis were swelling of the ciliary membrane, formation of compound cilia, dropping of epithelial cells, and metaplasia of a squamous epithelium. On the basis of these observations on ciliary beating and the fine structure of the mucosal epithelium, the severity of pathological change of the mucous membrane in chronic sinusitis was graded.

Chronic Disease↗
PubMed1983

Enhancement of ciliary action by a beta-adrenergic stimulant.

It is known that beta-adrenergic stimulants enhance mucociliary transport in the respiratory tract. The present study clearly indicated that such an enhancement resulted from not only the alteration in secretory function but also the direct stimulation of ciliated cells. However, the enhancement of ciliary beating depended on the morphological changes in ciliated cells. On the other hand, the effect of terbutaline aerosol, a beta-adrenergic stimulant, on patients with chronic sinusitis was evaluated by paranasal sinus radiography. Consequently, marked improvements in shadows were achieved after 4 weeks in 40% of the cases examined.

Adult↗
PubMed1983

[Clinical experience with cefotiam in the otorhinolaryngologic field].

Clinical investigation with cefotiam (CTM) was performed, the following results were obtained. CTM was administered to 18 cases of infectious diseases in the otorhinolaryngologic field. Clinical results were excellent in 7 cases, good in 5 cases, fair in 4 cases and poor in 2 cases. Clinical efficacy was 66.7%. No side reactions were noted in any cases.

Adult↗
PubMed1983

Appearance of fibronectin in rabbit cornea after thermal burn.

The sequence of the appearance of fibronectin in the rabbit cornea after thermal burn was investigated by indirect immunofluorescent microscopy. One day after thermal burn, the keratocytes disappeared completely from the burned area, and faint fibronectin-specific fluorescence was detected beneath the epithelium and on the stromal side of the Descemet's membrane. On day 3, activated keratocytes began to migrate to the burned lesion. Fibronectin was detected in the burned area as well as in the surrounding uninjured area, and on both sides of the Descemet's membrane. One week after the burn, the keratocytes had increased in the lesion and, concomitantly, fibronectin-specific fluorescence could be observed at the locations corresponding to the keratocytes. Fibronectin in the surrounding area gradually diminished. After 4 weeks, activated keratocytes had accumulated in the lesion, and fibronectin was detected only in the central lesion and at the level of the Descemet's membrane. Thus the appearance of fibronectin was concordant with the appearance of the keratocytes, and this suggests that fibronectin may be involved in the wound-healing of thermally burned rabbit corneas.

Animals↗
PubMed1983

Inhibition of DNA ligase activity by histones and its reversal by poly(ADP-ribose).

The molecular mechanism by which poly(ADP-ribose) participates in DNA repair was investigated using purified DNA ligase in DNA-histone systems. The ligase activity was markedly inhibited by histones; the inhibition was greater than 80% with histone H1 at concentrations equal to DNA. This inhibition was reversed efficiently by poly(ADP-ribose), either added exogenously or synthesized in situ with poly(ADP-ribose) synthetase. The reversal effect was specific for poly(ADP-ribose); other polyanions such as mRNA, rRNA's, tRNA, and synthetic poly(A) were less effective or totally ineffective. The poly(ADP-ribose) effect appeared to be caused by binding to histones and decreasing DNA-histone interactions. Poly(ADP-ribose) also had high affinity for DNA ligase. These observations, together with the findings of absolute dependence of poly(ADP-ribose) synthetase activity on DNA strand ends and extensive automodification of the synthetase in DNA-damaged cells, suggested a possible mechanism of poly(ADP-ribose) action in DNA repair, in which auto-modified poly(ADP-ribose) synthetase serves as a link between DNA damage and activation of DNA ligase.

DNA Ligases↗
PubMed1983

Conformations of fortimicins and three-dimensional structure-activity relationship in the aminoglycoside antibiotics.

The fortimicins are pseudodisaccharide antibiotics consisting of purpurosamine and fortamine moieties which are connected through an alpha-linkage. NMR spectra indicate that the fortamine ring in fortimicin A takes a chair conformation which corresponds to an inverted one in the conformation of fortimicin B free base. Fortimicin A is unstable in solution, and we were unable to obtain any crystals of it. To elucidate the structure of fortimicin A and to clarify the stereochemistry of fortimicins, we have undertaken to calculate their empirical force-fields starting from the X-ray structures of fortamines and fortimicin B free base. Nuclear Overhauser enhancement data were also employed to confirm the calculated relative orientation of the two rings around the glycosidic linkage. The 3-dimensional structure-activity relationship of aminoglycoside antibiotics is discussed on the basis of these results.

Aminoglycosides↗
PubMed1982

Quantitative analysis of beta-lactamase production of multiple resistance to beta-lactam antibiotics in clinical isolates of Escherichia coli.

A simple test of procedure is described for the rapid evaluation of beta-lactamase substrate profiles against all the clinically important beta-lactam antibiotics. By use of this method 100 clinical isolates of Escherichia coli were classified into four beta-lactamase types: TEM-like, 35; chromosomal-like, 56; others, 3; beta-lactamase-less, 6 strains. They were tested for their susceptibilities to cefuroxime, cefoxitin, cefamandole, cephalexin, cefazolin, cephaloridine, cephalothin, ampicillin, carbenicillin and kanamycin. The isolates of each of TEM-like and chromosomal-like beta-lactamase types showed a good correlation between the beta-lactamase activity and the minimum inhibitory concentration (MIC) determined by the agar dilution method and the least square line analysis; MIC = ax + b, where x is enzyme activity, and a and b are constants. TEM-like beta-lactamase increased the resistance to ampicillin and carbenicillin markedly and that to cephalothin, cephaloridine and cefamandole moderately. In contrast, chromosomal-like beta-lactamase increased the resistance to ampicillin, cephalexin and cephalothin only slightly.

Anti-Bacterial Agents↗
PubMed1982

[Studies on industrial styrene poisoning (Part XIII). Experimental studies on the damage on the mucosal membrane of respiratory tracts of rats exposed to styrene-contemporary observations of the changes in ciliary function and fine structures].

Styrene is known to have an irritating effect on the tracheal mucosa, but there are few reports that have demonstrated it histologically. We carried out styrene-exposure experiments on rats, and made observations on morphological changes of the trachea with an electron-microscope. Observations on its functional aspects were also made by estimation of the ciliary movement per minute. The present study has revealed a considerable damaging effect of styrene on the tracheal mucosa, which we presented in this report in the hope that it could be used as an index in settling the maximum permissible concentration of styrene for the future.

Animals↗