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Biomedical subjects

E Oh

Publications and source records attributed to E Oh.

16 recordsLinked to original sources
PubMed1997

Are rheumatoid arthritis patients more willing to accept non-steroidal anti-inflammatory drug treatment risks than osteoarthritis patients?

One hundred and thirty-four patients with either osteoarthritis or rheumatoid arthritis, and with a history of current or past non-steroidal anti-inflammatory drug (NSAID) treatment, were interviewed regarding the benefits, expectations and side-effects of NSAID therapy. Their willingness to accept risks in medical treatment was also evaluated. Both groups experienced positive effects of the NSAID treatment corresponding to their expectations. However, rheumatoid arthritis patients were significantly more willing to accept gastrointestinal side-effects when given an effective NSAID than the osteoarthritis patients, and they were also more willing to take risks in trying a hypothetical new NSAID that had been shown to be effective in clinical trials.

Adult↗
PubMed1997

Anti-rheumatic drug-prescribing behaviour of Australasian rheumatologists 1984-1994.

The prescribing behaviour of Australian and New Zealand rheumatologists was studied in 1994 using a questionnaire, and the results compared with a similar questionnaire administered in 1984. Perceived differences in efficacy and toxicity for disease-modifying anti-rheumatic drugs (DMARDs) and cytotoxics were reported. Over the decade, methotrexate and sulphasalazine have become the most commonly used anti-rheumatic agents, and methotrexate is clearly seen as the most effective drug. Wide variations in monitoring practices for DMARDs were reported, highlighting the need for cost-effectiveness studies on monitoring. There was low usage of functional outcome measurements in assessing patients.

Australia↗
PubMed1996

Rapid attenuation of AP-1 transcriptional factors associated with nitric oxide (NO)-mediated neuronal cell death.

Stimulation of glutamate receptors causes several intracellular reactions including activation of activator protein-1 (AP-1) production and nitric oxide (NO) generation. Exposing mouse cerebellar granule cells to N-methyl-D-aspartate or kainate (KA) in culture induced an increase of AP-1 DNA binding activity that was blocked by further addition of sodium nitroprusside (SNP), a typical NO donor. Immunoblotting using anti-c-Fos antiserum revealed the specific attenuation of AP-1, although total protein synthesis was not affected. Since the level of c-fos mRNA expression stimulated by KA remained constant even after exposure to SNP, the AP-1 attenuation can be post-transcriptionally induced. SNP did not affect the Ca2+ influx into the cells stimulated by KA. The involvement of NO in the AP-1 attenuation was supported by the fact that potassium ferrocyanide (K4Fe(CN)6), an analogue of SNP but devoid of NO, failed to inhibit the AP-1 DNA binding activity stimulated by KA. SNP alone induced neuronal cell death, which was blocked by the simultaneous addition of antioxidants, superoxide dismutase and catalase, and an NO scavenger, suggesting a direct role of peroxynitrite in the cell death. In good agreement with these effects, the AP-1 attenuation by SNP was also blocked by antioxidants. These results indicated that post-transcriptional attenuation of AP-1 is involved in the early processes of NO-mediated neuronal cell death.

Animals↗
PubMed1996

Psychometric functions for the discrimination of spectral variance.

An experiment was conducted to measure the shape of the psychometric function for the discrimination of spectral variance. The stimuli were simultaneous tone complexes comprised of the six octave frequencies from 250 to 8000 Hz. On each presentation the levels of components in dB were drawn independently and at random from one of two normal distributions having identical means but different variances (sigma N = 1 dB, sigma S = 2-10 dB). In the standard two-interval, forced-choice procedure, the listeners' task was to indicate which complex had the greater variance in component level. The shape of the psychometric function for all five listeners was markedly different from that of an observer limited only by additive internal noise. It was consistent with an observer that gives weight to only one or two components in the complex. However, this result was inconsistent with the weighting functions computed from the trial-by-trial data from these listeners. Both measures can be reconciled if it is assumed that listener weights vary from trial to trial, or that decisions are based on the one tone in the complex having the maximum level.

Adult↗
PubMed1996

Upper airway and soft tissue structural changes induced by CPAP in normal subjects.

Nasal continuous positive airway pressure (CPAP) is the treatment of choice for adults with obstructive sleep apnea. CPAP is known to increase upper airway size; however, the direct effects of CPAP on soft tissue structures surrounding the upper airway are less well understood. Magnetic resonance imaging was used to study the effect of incremental levels (0, 5, 10, and 15 cm H2O) of CPAP on the upper airway and surrounding soft tissue structures in 10 normal subjects. Progressive increases in CPAP resulted in the following major findings: (1) airway volume and airway area (measured at several different locations [midregion, minimal, maximal]) within the retropalatal and retroglossal regions increased; (2) lateral airway dimensional changes were greater than anterior-posterior changes; (3) lateral upper airway soft tissue structural changes were significantly greater than anterior-posterior changes; (4) lateral pharyngeal wall thickness decreased and the distance between the lateral parapharyngeal fat pads increased. An inverse relationship was demonstrated between CPAP level and pharyngeal wall thickness; (5) minimal changes were noted in the soft palate and tongue. These data suggest that the lateral pharyngeal walls are more "compliant" than the soft palate and tongue. This investigation provides further evidence that the lateral pharyngeal walls play an important role in mediating upper airway caliber.

Adult↗
PubMed1995

Determination of the mechanism for the decrease in zinc oxide surface area upon high-temperature drying.

High-temperature drying is required to remove chemisorbed water from the zinc oxide surface. High-temperature drying of a very small particle size zinc oxide powder (median particle size approximately 23 nm) resulted in a substantial decrease in the surface area. The surface areas (BET analysis of 77 K nitrogen vapor adsorption data) of ZnO samples dried at 500 degrees C decreased continually as the drying time was increased. Although the surface area decrease was fastest during the first 5 h, a 64% decrease in surface area was found after 20 h. The decrease in surface area was not due to a collapse of pore structure. Comparison of nitrogen vapor adsorption and desorption isotherms as well as geometric calculations of surface area indicated that both the original and final particles were nonporous. X-ray diffractograms of the original powder and of powders dried at two temperatures were all identical. Thus, no change in crystal structure occurred as a result of drying at 500 degrees C. Atomic force microscopy provided substantial evidence that the surface area decrease was due to a shift in the particle size distribution to a larger mean size. It was verified using two different experiments that ZnO exhibited significant sublimation at 500 degrees C. It was concluded that the increase in particle size was due to a sublimation/condensation process that obeyed the Kelvin equation. The effect of ZnO particle size on the vapor pressure ratio in the Kelvin equation was modeled at 500 degrees C for several different assumed solid surface tensions. Drying conditions for ZnO were then selected which balanced maximum removal of chemisorbed water and minimum surface area decrease. Water vapor adsorption isotherms for ZnO at 25 degrees C were subsequently obtained. Differences in the isotherms resulting from the presence or absence of a chemisorption contribution could clearly be demonstrated.

Adsorption↗
PubMed1995

Involvement of protein kinase C in Ca(2+)-signaling pathways to activation of AP-1 DNA-binding activity evoked via NMDA- and voltage-gated Ca2+ channels.

Stimulation of cultured cerebellar granule cells with N-methyl-D-aspartate (NMDA) or kainic acid (KA) leads to activation of activator protein-1 (AP-1) DNA-binding activity, which can be monitored by an increase in 12-O-tetradecanoylphorbol 13-acetate (TPA)-responsive element (TRE)-binding activity, in concert with c-fos induction. For this increase in TRE-binding activity, Ca2+ influx across the plasma membrane is essential. Treatment of cells with an intracellular Ca2+ chelator, BAPTA-AM, abolished this increase. Close correspondence between the dose-response curves of 45Ca2+ uptake and TRE-binding activity by NMDA or KA suggested that Ca2+ influx not only triggered sequential activation of Ca(2+)-signaling processes leading to the increase in TRE-binding activity, but also controlled its increased level. Stimulation of non-NMDA receptors by KA mainly caused Ca2+ influx through voltage-gated Ca2+ channels, whereas stimulation of NMDA receptors caused Ca2+ influx through NMDA-gated ion channels. The protein kinase C (PKC) inhibitors staurosporine and calphostin C inhibited the increase in TRE-binding activity caused by NMDA and KA at the same concentration at which they inhibited that caused by TPA. Furthermore, down-regulation of PKC inhibited the increase in TRE-binding activity by NMDA and KA. Thus, a common pathway that includes PKC could, at least in part, be involved in the Ca(2+)-signaling pathways for the increase in TRE-binding activity coupled with the activation of NMDA- and non-NMDA receptors.

Animals↗
PubMed1994

Modulation of AP-1 activity by nitric oxide (NO) in vitro: NO-mediated modulation of AP-1.

To understand the role of nitric oxide (NO) in controlling the specific DNA-binding activities of transcriptional factors, we investigated the in vitro effect of the NO-donor sodium nitroprusside (SNP) on the AP-1 activity of cultured mouse cerebellar granule cells. A gel-mobility assay showed that SNP inhibited AP-1 activity in the presence, but not the absence of dithiothreitol (DTT). This DTT-dependent inhibition of AP-1 activity by SNP corresponded with the activation of the chemical reactivity of SNP with DTT, which can be monitored by the production of nitrite (NO2-). In contrast, diamide, a typical sulfhydryl oxidizing agent, inhibited AP-1 activity in the absence of DTT and its inhibitory effect was reversed competitively by DTT. Studies using structurally or functionally related analogues of SNP demonstrated that S-nitrosylation of the AP-1 moiety mediated by some NO-carriers but not by free NO, which can be produced by the chemical reaction of SNP with DTT, was responsible for the inhibition of AP-1 activity, suggesting NO-mediated regulation of the AP-1 transcriptional factor.

3T3 Cells↗
PubMed1991

Mixed chimerism to induce tolerance for solid organ transplantation.

Chimerism, or the coexistence of tissue elements from more than one genetically different strain or species in an organism, is the only experimental state that results in the induction of donor-specific transplantation tolerance. Transplantation of a mixture of T-cell-depleted syngeneic (host-type) plus T-cell-depleted allogeneic (donor) bone marrow into a normal adult recipient mouse (A + B----A) results in mixed allogeneic chimerism. Recipient mice exhibit donor-specific transplantation tolerance, yet have full immunocompetence to recognize and respond to third-party transplantation antigens. After complete hematolymphopoietic repopulation at 28 days, animals accept a donor-specific skin graft but reject major histocompatibility complex (MHC) locus-disparate third-party grafts. We now report that permanent graft acceptance can also be achieved when the graft is placed at the time of bone marrow transplantation. Histologically, grafts were viable and had only minimal inflammatory changes. This model may have potential future clinical application for the induction of donor-specific transplantation tolerance.

Animals↗
PubMed1991

Mixed allogeneic reconstitution (A+B----A) to induce donor-specific transplantation tolerance. Permanent acceptance of a simultaneous donor skin graft.

Mixed allogeneic reconstitution, in which a mixture of T-cell-depleted bone marrow of syngeneic host and allogeneic donor type is transplanted into a lethally irradiated recipient (A+B----A), results in mixed lymphopoietic chimerism with engraftment of a mixture of both host and donor bone marrow elements. Recipients are specifically tolerant to donor both in vitro and in vivo. Donor-specific skin grafts survive indefinitely when they are placed after full bone marrow repopulation at 28 days, while third-party grafts are rapidly rejected. To determine whether a delay of a month or more for full bone marrow repopulation is required before a donor-specific graft can be placed, we have now examined whether tolerance induction can be achieved if a graft is placed at the time of bone marrow transplantation. Permanent acceptance of donor-specific B10.BR skin grafts occurred when mixed allogeneic chimerism (B10+B10.BR----B10) was induced and a simultaneous allogeneic donor graft placed. In vitro, mixed reconstituted recipients were specifically tolerant to the B10.BR donor lymphoid cells but fully reactive to MHC-disparate third-party (BALB/c; H-2dd) when assessed by mixed lymphocyte reaction (MLR) and cell-mediated lympholysis (CML) assays. These data therefore indicate that a donor-specific graft placed at the time of mixed allogeneic reconstitution is permanently accepted without rejection. To determine whether an allogeneic skin graft alone without allogeneic bone marrow would be sufficient to induce tolerance, syngeneic reconstitution (B10----B10) was carried out, and a simultaneous B10.BR allogeneic skin graft placed. Although skin grafts were prolonged in all recipients, all grafts rejected when full lymphopoietic repopulation occurred at 28 days. Taken together, these data suggest that allogeneic donor bone marrow elements are required for the induction and maintenance of donor-specific transplantation tolerance and that allogeneic skin grafts alone are not sufficient for tolerance induction.

Animals↗
PubMed1988

A human monoclonal antibody to cytokeratin intermediate filament antigens derived from a tumor draining lymph node.

Human lymphocytes derived from a lymph node draining a primary breast adenocarcinoma were fused with the mouse myeloma P3X63Ag8.653 to generate human-mouse hybridomas secreting human monoclonal antibodies (MAbs) to tumor associated antigens (TAAs). One of the resulting human MAbs, YBB 190 (IgM) is described. Enzyme-linked immunosorbent assays (ELISA) employing membrane and cytosol fractions of human tissues demonstrated YBB 190 reactivity against cytosol but not membrane components of malignant and normal epithelial tissues. When tested by an indirect immunoperoxidase staining method against fresh frozen human tissue sections, YBB 190 reacted with malignant cells in 26 of 28 epithelial cancers and with normal epithelia in 11 different benign tissues. Preliminary western blot antigen characterization indicated that YBB 190 recognizes cytokeratin intermediate filaments, or a protein that is closely associated with cytokeratins. These data indicate that B cells with specificity for intermediate filaments are present in tumor draining lymph nodes. Our findings provide insights into the nature of potential autoimmune responses in cancer patients and suggest that improved tumor directed sensitization procedures may be required to more effectively utilize lymphocytes from tumor draining lymph nodes to generate therapeutically useful human MAbs to TAAs.

Adenocarcinoma↗
PubMed1981

Deposition of plasma fibronectin in tissues.

Tissue distribution of human fibronectin injected intravenously into mice was studied by using immunofluorescence with species-specific antisera to human and mouse fibronectins. Human fibronectin was detected in the tissues of mice injected with human fibronectin. The distribution of the injected fibronectin was indistinguishable from that of mouse fibronectin. The staining for human fibronectin in the livers of injected mice was unaffected by perfusion of the livers prior to the preparation of tissue sections, and human IgG injected in mice as a control was not detectable in tissues by immunofluorescence. Mice were also injected with fragments of fibronectin with molecular weights close to 200,000. These fragments lack parts of the NH2 and COOH termini of the fibronectin polypeptide, including the part with the interchain disulfide bond(s), but retain the ability to bind to collagen and heparin and the ability to mediate cell attachment. They showed essentially no tissue incorporation, suggesting that the integrity of the fibronectin molecule is important for the accumulation of fibronectin in tissues. The incorporation of injected fibronectin into tissues demonstrated here suggests that circulating fibronectin contributes to the extracellular matrix of tissues.

Animals↗
PubMed1980

Differences in the nuclear proteins of normal and malignant liver cells.

Immunological tests and 2-dimensional gel electrophoresis revealed differences between the nuclear proteins from normal and malignant liver cells. Immunization of rabbits with a nuclear nonhistone protein fraction isolated from normal mouse liver resulted in antisera that in immunofluorescence gave nuclear staining in sections of normal liver, but did not stain nuclei of a transplantable mouse hepatoma. Antisera prepared against a nuclear protein fraction from the hepatoma allowed immunofluorescent staining of hepatoma nuclei but did not stain nuclei from normal liver. Nuclei in liver regeneration after injury caused by administration of carbon tetrachloride stained with antiserum against normal nuclei but not with antisera against hepatoma nuclei. Neither antiserum stained nuclei in fetal liver cells. The presence of differing sets of nuclear proteins in the normal and malignant liver cells was indicated by 2-dimensional gel electrophoresis. Approximately 300 polypeptides were resolved by this technique. Most of these were quantitatively different in the normal and hepatoma nonhistone protein preparations. Several qualitative differences also seemed to be present. Nonhistone proteins from regenerating liver shared some polypeptides with hepatoma that were absent in normal liver. Nuclear proteins characteristic of malignant tissues may provide clues toward the understanding of gene regulation in malignant cells, and some of them could become useful tumor markers.

Animals↗
PubMedDate not supplied

Spectral titration of active site of carboxypeptidase A.

In the carboxypeptidase A-catalyzed hydrolysis of O-[trans-alpha-(benzoylamino)-cinnamoyl]-L-beta-phenyllactate (BACPL) or O-[trans-alpha-(benzoylamino)-p-(phenylazo)cinnamoyl]-L-beta-phenyllacta te (BAPACPL), biphasic kinetic behavior was observed due to the accumulation of an intermediate. At -12 degrees C, conversion of the intermediate into the product was much slower than the formation of the intermediate, which accumulated in quantitative amounts. From the absorbance changes observed during the formation process of the intermediate, the concentration of active site of the enzyme was determined.

Binding Sites↗
PubMedDate not supplied

Independent origin of the hepatic and splenic arteries from the abdominal aorta: CT demonstration.

PURPOSE: The purpose of this work was to illustrate the CT appearance of the independent origin of the hepatic and splenic arteries from the abdominal aorta. METHOD: A retrospective review of available scans from 159 consecutive contrast-enhanced abdominal CT examinations was undertaken to document the frequency with which this vascular variant is seen at helical CT. RESULTS: Independent origin of the hepatic and splenic arteries was seen in 2 of 159 examinations (1.3%). This correlates well with the 1% incidence reported in the angiographic and surgical literature. CONCLUSION: Independent origin of the hepatic and splenic arteries from the aorta should be seen in approximately 1% of abdominal CT examinations. Knowledge of this vascular variant and its CT appearance may prevent confusion or mislabeling.

Aorta, Abdominal↗