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Biomedical subjects

M L Chang

Publications and source records attributed to M L Chang.

At least 55 records · Page 3Linked to original sources
PubMed1990

Interferon production from peripheral blood, synovial fluid, and synovial tissue lymphocytes in patients with rheumatoid arthritis and ankylosing spondylitis.

A previous study demonstrated that interferon was present in the serum of 30% of the patients with systemic lupus erythematosus (SLE), which was significantly higher than the 4.5% found in normal controls. We also recently reported that interferon production was deficient from SLE mononuclear cells, which has been attributed to immunodeficiency of the lymphocytes. In this study, interferon measurement included lymphocytes obtained from peripheral blood (PB), synovial fluid (SF) and synovial tissue (ST) in patients with rheumatoid arthritis (RA) and ankylosing spondylitis (AS). PB from normal subjects (NS) was used as a control. The results showed with PHA stimulation, that the interferon level in PBL (L = lymphocyte) in NS (70.0 +/- 67.5) was significantly higher when compared with PBL in RA (27.9 +/- 21.6). However, there was no difference between PBL in NS and AS. With ConA stimulation, the interferon level was significantly higher in the PBL of NS (130 +/- 59) and as compared with the PBL in RA (83.6 +/- 53.5). The SFL in RA (67.8 +/- 31.1) and the STL in RA (77.2 +/- 93.2) were also significantly different. It is concluded that interferon production was deficient not only in PBL in RA, but also in SF and STL in RA. The reduced interferon production from PB, SF and ST lymphocytes in RA patients may be due to previous release or immunodeficiency. Lymphocyte interferon production was normal in AS, which suggests that the lymphocyte abnormality between RA and AS may be different.

Adult↗
PubMed1990

[The occurrence and clinical significance of antibodies to type II collagen in sera and synovial fluid of Chinese patients with rheumatoid arthritis].

Antibodies to type II collagen (Col II) in sera and synovial fluid (SF) were measured with an enzyme linked immunosorbent assay (ELISA) using a solid phase sandwich method. The subjects included: 42 patients with rheumatoid arthritis (RA); 31 cases of osteoarthritis (OA); 10 cases of gouty arthritis; 4 cases of ankylosing spondylitis (AS); 5 cases of systemic lupus erythematosus (SLE); and 44 normal controls. The antigens used to detect antibodies against Col II were in native and heat-treated denatured forms, both of which were purified from chicken sternal cartilage by limited enzyme digestion and differential precipitation with salt. The reactivity to native type II collagen was generally higher than the reaction to the denatured collagen. In sera, significant higher levels of Col II were detected in the different arthritis groups when compared with the normal control group, with the exception of AS. In SF, the Col II was significantly higher in RA than it was in OA (p less than 0.001), while no difference was present between gout and OA (p less than 0.05). When native Col II was simultaneously measured in sera and SF among arthritics, positive rates were both higher among RA (65% and 58%, respectively). Positive rates were only higher in sera among OA (59% in sera and 3% in SF) and were both lower among gouty arthritis. The above findings show that the measurement of Col II is more important in SF than in sera.

Arthritis, Rheumatoid↗
PubMed1988

[The interrelationships of hepatitis B e antigen antibody and HBsAg-circulating immune complexes in asymptomatic HBsAg carriers].

The prevalence of asymptomatic HBsAg carriers and positive rate of HBsAg immune complexes (HBsAg-CICs) were comparatively higher among Chinese. The former is considered to be related with hepatitis B e antigen and the latter is not clear yet. In order to investigate the relationship between HBsAg-CICs and e antigen antibody among asymptomatic carriers. 90 subjects of carriers was tested for HBsAg-CICs by PEG-trypsinisation method and for e antigen antibody by radio-immunoassay. HBsAg-CICs were positive in 66 subjects among 90 carriers. The concentration of HBsAg-CICs (ng/ml) was significantly higher among 32 subjects with positive HBeAg (333.87 +/- 265.39) than 27 subjects with positive anti-HBe (181.03 +/- 162.05), p less than 0.02. Furthermore, the positive rate of e antigen and e antibody was just contrary among carriers with positive and negative HBsAg-CICs. Among 24 subjects with negative HBsAg-CICs, the percentage of positive HBeAg was much lower than positive e antibody. A significant interrelationship was present between positive or negative HBsAg-CICs and e antigen, antibody, the statistically significant was proved by the Chi square test. The above results showed that the high prevalence of asymptomatic HBsAg carriers among Chinese may be related to e antigen.

Antigen-Antibody Complex↗
PubMed1987

[Specific circulating immune complexes in patients with hepatitis B].

Antigen specific hepatitis B surface antigen circulating immune complexes (HBsAg-CICs) were measured in 109 cases of hepatitis B with positive HBsAg (among them, 49 cases were acute and 60 cases were chronic hepatitis), 96 cases of asymptomatic hepatitis B surface antigen carriers, and 95 cases of normal blood donors. The mean concentration (ng/ml) of HBsAg-CICs was 303.50 +/- 357.70, 319.26 +/- 334.35 and 179.66 +/- 234.26 for the first three groups respectively; and was negative in normal groups. The concentration of HBsAg-CICs were significantly higher in acute and chronic group when compared with the asymptomatic carrier's group, (p less than 0.02 and p less than 0.01, respectively). Longitudinal series studies showed a close correlation between the levels or changes of HBsAg-CICs and the activity of the disease; patients with persistent HBsAg-CICs had a poor prognosis; and this were true not only in acute but also in chronic hepatitis patients. The mean concentration of HBsAg-CICs was higher in patients with positive hepatitis B e antigen (HBeAg) than in negative; but lower in patients with hepatitis B e anti-body (anti-HBe) positive than in negative. The higher prevalence of HBsAg-CICs in sera among asymptomatic HBsAg carriers in our study might be related to the prevalence of HBeAg among Chinese carriers. Further more, because HBsAg-CICs was related to the activity and prognosis of hepatitis B, it is worthwhile reconsidering whether so called "healthy" carriers were really healthy when their sera HBsAg-CICs tested positive.

Antigen-Antibody Complex↗
PubMed1986

Differential inhibition of cardiac cyclic nucleotide phosphodiesterase isozymes by cardiotonic drugs.

Several new cardiotonic drugs are postulated to act as potent inhibitors of cyclic nucleotide phosphodiesterase activity. Unfortunately, the presence of multiple phosphodiesterase isozymes in cardiac muscle makes it difficult to determine whether any of these enzymes are specific targets for the cardiotonic agents. We have developed a method for rapid isolation and assay of bovine cardiac muscle phosphodiesterases using monoclonal antibodies that distinguish between isozymes without inhibiting catalytic activities. By this method, milrinone, amrinone, and MDL 17,043 were tested for potency as inhibitors of soluble bovine heart phosphodiesterases. All three drugs were highly selective for a low-Km, cyclic GMP (cGMP)-inhibited phosphodiesterase. IC50s (half-maximal inhibitory concentrations) for cGMP-inhibited phosphodiesterase were 0.5 microM (milrinone), 30 microM (amrinone), and 2 microM (MDL 17,043) when measured at 0.35 microM cyclic AMP (cAMP). Milrinone and MDL 17,043 had greater than 50-fold lower potencies for the other heart phosphodiesterases (and amrinone 20-fold). These data suggest the cGMP-inhibited phosphodiesterase as a probable site of action for these new cardiotonic drugs. In addition, the method described here should be useful for screening new drugs, and for studying physical and chemical properties of this phosphodiesterase/drug receptor in cardiac and other tissues.

Aminopyridines↗
PubMed1985

cGMP phosphodiesterase in rod and cone outer segments of the retina.

Immunochemical, chromatographic, and sodium dodecyl sulfate gel electrophoresis studies suggest that immunologically related but distinct cyclic GMP phosphodiesterases are present in rod and cone outer segments of the retina. Immunocytochemical studies demonstrated that one monoclonal antibody (ROS-1) recognized a determinant present in both rod and cone outer segments, while another monoclonal antibody (ROS-2) only recognized rod outer segments. At least two peaks of phosphodiesterase activity could be separated by high-performance anion-exchange chromatography of retinal extracts. Both peaks were recognized by ROS-1. None of the first peak and only 80% of the second broad peak of activity were recognized by ROS-2. High-performance liquid chromatography profiles from human fovea and several other types of cone-enriched retina showed that most of the activity was contained in the first peak, suggesting that this activity was derived from cone outer segments. Conversely, the phosphodiesterase in rod-enriched preparations migrated predominately in the second peak. Sodium dodecyl sulfate-gel electrophoresis indicated that this first peak contained a single large immunoreactive polypeptide (alpha') that migrated with the same mobility as a phosphorylase b standard and was distinct from the more rapidly migrating large immunoreactive polypeptides (alpha and beta) present in a broad second peak. The second peak could be further separated into a first part that contained a doublet of two immunoreactive polypeptides (alpha and beta) that migrated faster than phosphorylase b and a later part that contained only the most rapidly migrating polypeptide (beta). All of the peaks could be activated by histone or transducin:GTP, implying that all contained a small 11-kDa inhibitory subunit (gamma) of the enzyme. Since the larger (alpha') and smaller (beta) immunoreactive polypeptides could be completely separated from the alpha polypeptide and from each other, yet still retain the ability to be activated by histone or transducin, the data suggest that only a single species of polypeptide-inhibitor complex (e.g. alpha' gamma, alpha gamma, or beta gamma) was required for histone or transducin:GTP activation.

3',5'-Cyclic-GMP Phosphodiesterases↗
PubMed1982

Identification of cGMP-stimulated cyclic nucleotide phosphodiesterase in lung tissue with monoclonal antibodies.

Monoclonal antibodies (CGS-1, 2, 3, and 4) and rabbit antisera have been produced against bovine heart cyclic GMP-stimulated cyclic nucleotide phosphodiesterase. The monoclonal antibodies were all of the IgG1 subclass and had relatively high affinities (kd values, 1-5 X 10(-10) M), making them suitable for many sensitive immunological and analytical procedures. Most of the monoclonal antibodies did not inhibit the enzyme, which allowed a rapid and specific assay for this form of phosphodiesterase to be developed. All of the activity could be adsorbed from purified preparations of cGMP-stimulated phosphodiesterase by each of the antibodies indicating antigenic homogeneity of the cGMP-stimulated phosphodiesterase. Neither the monoclonal antibodies nor the antisera inhibited cGMP-binding to the phosphodiesterase. Substrate specificity, Electrophoresis, and cyclic GMP binding studies carried out on immunoadsorbed material indicated that a major part of the cyclic nucleotide phosphodiesterase activity present in bovine lung was due to the cyclic GMP-stimulated form. The presence of this enzyme was difficult to identify by other more common procedures and has not been previously demonstrated in this tissue. These studies also indicated that the cGMP-stimulated phosphodiesterase was immunologically distinct from the other major cGMP-binding proteins present in lung extract and that it could be separated from these binding proteins by chromatography on DEAE-cellulose. Finally, the data suggest that none of the other peaks of cyclic nucleotide phosphodiesterase activity, seen upon DEAE-cellulose fractionation of lung extracts, contain the immunological determinants present on the cGMP-stimulated form which are recognized by the antibodies.

3',5'-Cyclic-AMP Phosphodiesterases↗