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Biomedical subjects

J C Chang

Publications and source records attributed to J C Chang.

At least 181 records · Page 10Linked to original sources
PubMed1988

Bond strength of 4-META acrylic resin denture base to cobalt chromium alloy.

This study was designed to compare the bond strength of a conventional poly(methyl methacrylate) acrylic resin denture base (Lucitone 199) with a recently developed acrylic resin base containing 4-META (Meta-Dent) to CoCr metal alloy by using various designs representative of clinical situations. The mechanical bond strength of Lucitone 199 resin was compared with the chemical and combination chemical and mechanical bond strength of Meta-Dent resin. The following conclusions may be extrapolated from the results. 1. The highest bond strength was observed between Meta-Dent resin and the plain flat metal plate. 2. The second highest bond strength was observed between Meta-Dent resin and the flat metal plate with two posts. 3. The lowest bond strengths were observed between Meta-Dent resin and the samples containing mesh retentive mechanisms. 4. The mean bond strength of Lucitone 199 resin was highest for the flat metal plate with two posts, followed by the large mesh. Bond strength with the small-mesh samples was lowest. These differences were not statistically significant. 5. The mean bond strengths of Meta-Dent resin to flat metal plates with or without posts was significantly higher than any of the Lucitone 199 resin metal bond strengths, to the 99% confidence level. Additional studies will be necessary to confirm the validity of these conclusions with respect to clinical removable partial dentures. Longitudinal investigations will be required to reveal clinical performance of these resin systems.

Acrylic Resins↗
PubMed1988

Remission of chronic idiopathic myelofibrosis to busulfan treatment.

Three patients with chronic idiopathic myelofibrosis have responded to busulfan treatment with an excellent hematologic remission and reversal of myelofibrosis and myeloid metaplasia. Four months after busulfan therapy all three patients showed an improvement of hematocrit and hemoglobin and reduction of the number of leukoerythroblasts. Cellular bone marrow was re-established in two patients. A decrease of hepatomegaly and splenomegaly also occurred and was well correlated with the hematologic response. In one patient, when busulfan was discontinued for about 2 years after achieving an excellent remission, hematologic relapse was accompanied by increase of hepatomegaly and splenomegaly. When busulfan treatment was resumed, hematologic response and decrease of hepatomegaly and splenomegaly reoccurred. This observation has demonstrated the beneficial effect of busulfan in chronic idiopathic myelofibrosis; therefore, the role of busulfan in the management of this disease should be further investigated.

Aged↗
PubMed1988

Occupational risk of prostate cancer: a cancer registry-based study.

Previous studies have suggested that certain occupational groups may be at increased risk for prostate cancer. A cancer registry-based case-control study was conducted to investigate possible associations between various occupations and the risk of prostate cancer among 1,239 case subjects and 3,717 age-matched control subjects. Elevated relative risk estimates were observed for farmers, mechanics, sheet metal workers, separating machine operators, and for men employed in several manufacturing industries. These findings are discussed in the context of previous studies, and suggestions for future research are provided.

Adult↗
PubMed1987

Studies of the role of mast cells in contact sensitivity responses. Passive transfer of the reaction into mast cell-deficient mice locally reconstituted with cultured mast cells: effect of reserpine on transfer of the reaction with DNP-specific cloned T cells.

The role of mast cells in the elicitation of contact sensitivity (CS) responses was evaluated by transferring different aliquots of the same preparations of immune lymph node cells (I-LNC) into naive, genetically mast cell-deficient (WBB6F1-W/Wv or WCB6F1-S1/S1d) mice and the corresponding congenic normal (+/+) mice. We found that the 24-hr CS responses elicited in the recipient mast cell-deficient mice were statistically indistinguishable from those in the congenic +/+ mice according to four different criteria: micrometer measurements of ear swelling, ratios of the weight or [125I]iododeoxyuridine-labeled leukocyte infiltration-associated cpm in challenged and contralateral control ears, and amount of 125I-fibrin deposition. We also transferred I-LNC into WBB6F1-W/Wv mice which, 5 months earlier, had undergone local repair of their mast cell deficiency by the intradermal injection (into the left ear only) of growth factor-dependent cultured mast cells derived from congenic +/+ mice. When 24-hr CS responses were elicited in both ears of these mice, the reactions in the mast cell-reconstituted left ears were similar to those in the mast cell-deficient right ears. We also found that treatment of antigen-specific cloned T cells with reserpine in vitro markedly impaired their ability to transfer reactivity for CS, providing further evidence that reserpine can interfere with the expression of T-cell-mediated responses through effects independent of its action on mast cells.

Animals↗
PubMed1987

Re-presentation of the hapten dinitrophenol (DNP) to a DNP-specific T-cell line.

Using a DNP-specific, class II-restricted T-cell line C9, we asked whether normal spleen cells directly labeled with DNFB (DNP-SC) can stimulate DNP-specific T cells. C9 cells were established from BALB/c mice primed with syngeneic DNP-SC subcutaneously; they proliferated and produced IL-2 and MIF in a DNP-specific, I-A-restricted manner. We found that syngeneic DNP-SC alone, either unfixed or fixed with gluteraldehyde, could not stimulate C9 cells. However, when DNP-SC were added to cultures of C9 cells plus syngeneic fillers, but not allogeneic fillers, potent stimulation occurred. Allogeneic DNP-SC were also stimulatory provided the cultures contained filler cells syngeneic to the C9 responding T cells. DNP-protein conjugates, however, did not induce stimulation, indicating that the T cells are DNP specific but not hapten specific. Overnight coculture of DNP-SC and irradiated normal spleen cells also produced potent stimulator cells. However, generation of these stimulator cells was inhibited by addition of chloroquine to the culture medium. These findings indicate that syngeneic filler cells acquire DNP from the DNP-SC and re-present the hapten to the T cells in the context of IA. This process appears to require antigen processing by the filler cells. Collectively the results indicate that labeling of cell membranes with reactive haptens may not directly produce an immunogenic complex which is recognized by T cells.

Animals↗
PubMed1987

The effect of IgE-mediated mast cell degranulation on the expression of experimental contact sensitivity in the mouse.

The effects of mast cell activation/degranulation on the elicitation of contact sensitivity (CS) to oxazolone and dinitrofluorobenzene were investigated. Mice were actively sensitized to oxazolone by epicutaneous painting followed by ear challenge. Passive sensitization to DNFB was induced by intradermal injections of dinitrophenol (DNP)-specific cloned T cells in the ears. Mast cells in the challenged ears were activated in various time periods by inducing a passive cutaneous anaphylaxis reaction where passive sensitization with monoclonal IgE anti-DNP antibodies was followed by iv injection of DNP-BSA. This combination of immediate and delayed-type hypersensitivity reactions resulted in a significant increase of ear swelling without any noticeable effect on cellular infiltration when the contact response was evaluated a short time (3-4 hr) after mast cell activation. The very same results were obtained in naive (unsensitized) mice, indicating that this reaction was nonspecific. However, when the CS reaction was evaluated at its peak, i.e., 24 hr post challenge, mast cell activation that had been induced 0.5-11 hr after ear challenge did not have any significant effect on both swelling and cellular infiltration when the latter was evaluated by a radiometric assay. We conclude that in these systems mast cell activation/degranulation makes little or no contribution to the modulation of T-cell activity.

Animals↗
PubMed1987

Nonfatal pulmonary edema after "freebase" cocaine smoking.

Pulmonary edema is known to develop in users of heroin and methadone. Its association with cocaine use is usually a postmortem finding. There has been only 1 report of pulmonary edema being diagnosed clinically after cocaine use. In that case the cocaine was used intravenously, and death occurred within 3 h after the onset of symptoms. Here we describe a patient who developed acute pulmonary edema after smoking "freebase" cocaine. The pulmonary edema resolved spontaneously within 72 h. The cause of the acute reversible pulmonary edema was probably related to both pressure- and permeability-related changes.

Acute Disease↗
PubMed1987

Occupation, smoking, and alcohol in the epidemiology of bladder cancer.

We conducted a case-control study to evaluate the effects of occupation, smoking, and alcohol consumption on bladder cancer risk. A total of 823 male cases and 2,469 age-matched controls were identified through the Missouri Cancer Registry. Relative risk estimates of 2.0 or greater were observed for janitors and cleaners, mechanics, miners, and printers. Current cigarette smoking was associated with a two-fold excess risk of bladder cancer, whereas alcohol consumption showed no association with bladder cancer risk.

Alcohol Drinking↗
PubMed1987

Hemoptysis in sarcoidosis.

The medical records of 433 patients with sarcoidosis were reviewed to determine the prevalence and significance of hemoptysis in this disease. Twenty-five patients (6%) were found to have hemoptysis. Nineteen of the 25 patients had mild hemoptysis, four had moderate, and two had massive hemoptysis. The clinical, roentgenographic, and laboratory features in patients with hemoptysis were compared with those from an age, race, and sex matched control group of sarcoidosis patients without hemoptysis. With the exception of eye involvement which occurred with greater frequency in control patients, no significant differences were found between the two groups. While bronchoscopy may be useful in establishing a diagnosis of endobronchial sarcoidosis, identification of a specific bleeding site is not likely in the absence of massive hemoptysis or localized radiographic abnormalities. Corticosteroid therapy may be useful to control hemoptysis in some patients.

Adult↗