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Biomedical subjects

J L Wang

Publications and source records attributed to J L Wang.

18 recordsLinked to original sources
PubMed1979

Allergic bronchopulmonary aspergillosis in pediatric practice.

Twelve cases of allergic bronchopulmonary aspergillosis in the pediatric age group are reported. The average age of diagnosis was 14.5 years with a range from 6 to 18 years. All patients had a history of pulmonary infiltrations or atelectasis or both documented by chest radiographs. Eight patients had bronchograms or tomograms, and seven of them showed proximal bronchiectasis. Total serum IgE concentrations were elevated in all patients. Preciptitating antibodies against Aspergillus fumigatus were positive in all patients at the time of diagnosis, and became negative in some after therapy. The specific IgE or IgG antibody activity agaist Af was elevated in all 12 patients. After prednisone was started the total serum IgE sharply declined to a plateau and remained at this level until a flare of allergic aspergillosis occurred. A flare of allergic aspergillosis is characterized by an increasing total serum IgE concentration followed by pulmonary infiltration. Clinical and roentgenologic improvements were observed after steroid therapy. The importance and methods of early diagnosis in the pediatric population are discussed.

Adolescent↗
PubMed1979

Growth control in cultured 3T3 fibroblasts. Assays of cell proliferation and demonstration of a growth inhibitory activity.

Treatment of sparse, proliferating cultures of 3T3 cells (target cells) with medium conditioned by exposure to density-inhibited 3T3 cultures resulted in an inhibition of growth and division in the target cells when compared to similar treatment with unconditioned medium (UCM). This differential effect of conditioned medium (CM) and UCM on target cells was demonstrated using three assay systems: (a) assessment of total cell number; (b) measurement of [3H]thymidine incorporated into acid-precipitable DNA; and (c) determination of the percentage of radioactively labeled nuclei in individual cells after incorporation of [3H]thymidine. The difference in the total incorporation of [3H]thymidine in CM-treated and UCM-treated cells was reflected by a difference in the percent of labeled cells. There was no differences in the average number of grains per labeled cell in the two cultures. Moreover, the inhibitory effect of the CM on target cell proliferation was reversible. Finally, this growth inhibitory activity can be collected in serum-free medium, precipitated by ammonium sulfate, and fractionated by gel filtration. In these purification procedures, the inhibitory activity was consistently found to be associated with the protein-containing fractions of the CM. No activity was found upon similar treatment with UCM. These results suggest that a system has been developed for the purification and molecular analysis of growth inhibitory factors that may mediate growth control in culture fibroblasts.

Animals↗
PubMed1979

The management of allergic bronchopulmonary aspergillosis.

Twenty-five patients with allergic bronchopulmonary aspergillosis (ABPA) were observed for periods of 12 months to 10 years (average duration, 2.6 years) after initial therapy with prednisone, which was then tapered and discontinued unless maintained at minimal doses as required for control of asthma. Thirteen patients have had no recurrence, 4 patients did not comply with the initial regimen and could not be considered to be controlled, and 8 patients had 12 recurrent episodes of ABPA characterized by pulmonary infiltrates with no explanation other than ABPA. The exacerbations were closely correlated with sharp increases in total serum IgE, which subsequently decreased after resumption of prednisone therapy. The increase of IgE preceded the pulmonary infiltrates in 7 or 12 exacerbations. The exacerbations, characterized by increased serum IgE and pulmonary infiltrates, may be associated with minimal symptoms. Acute asthma without pulmonary infiltrates was not associated with increased IgE. Four exacerbations occurred during administration of beclomethasone diproprionate used for control of asthma, and therefore, this agent does not appear to prevent or reverse exacerbations of ABPA. Twelve exacerbations occurred in 8 persons, with 2 patients having 4 and 2 recurrences, respectively. This suggests that exacerbations are more likely to occur in certain patients. Serial measurements of total serum IgE appears to be a useful index of disease activity in ABPA. In the 4 patients who did not comply with the prednisone therapy regimen or regular physician visits, patterns of IgE changes, clinical evaluations, and chest roentgenograms were not of use in evaluation of the clinical state or progress of the patient. A treatment regimen is suggested for initial therapy and recurrences of ABPA on the basis of these observations.

Aspergillosis, Allergic Bronchopulmonary↗
PubMed1979

IgA and IgG antibody activities of serum and bronchoalveolar fluid from symptomatic and asymptomatic pigeon breeders.

Serum IgA and IgG antibody activities against pigeon serum were measured in 16 symptomatic pigeon breeders, 20 asymptomatic pigeon breeders, and 3 normal subjects by radioimmunoassay. The IgA and IgG antibody activities against pigeon antigen of the group of patients with disease was significantly greater than those of patients in the asymptomatic and the control group. The overlap of results for the symptomatic and asymptomatic breeders limits the diagnostic value of these individual IgA or IgG antibody determinations. Bronchoalveolar fluid and serum samples from a smaller group of pigeon breeders who underwent lung lavage were available for studies of antibody activity against pigeon serum. Ten asymptomatic and 6 symptomatic breeders were available for study. Both IgG and IgA antibody activities were detected by radioimmunoassay in serum samples and bronchoalveolar fluid. The IgA antibody activity determined by the radioimmunoassay was higher in the respiratory secretions.

Alveolitis, Extrinsic Allergic↗
PubMed1978

Binding and functional properties of concanavalin A and its derivatives. II. A proteolytic product with saccharide-binding activity.

Limited digestion of the intact subunit of concanavalin A (Mr = 26,000) with trypsin followed by affinity chromatography on Sephadex G-100 has yielded a highly purified product designated here as Tn-Con A. Chemical studies have shown that Tn-Con A is composed of several components: a large fragment (Tn I, Mr = 19,000) spanning residues 1 to 172, and lower molecular weight polypeptides that are noncovalently associated with Tn I to form the active molecule. The molecular weight of Tn-Con A at pH 7 was 90,000, suggesting that, like native concanavalin A, it was a tetramer at physiological pH. Equilibrium dialysis experiments showed that Tn-Con A bound 1 molecule of alpha-methyl-D-glucoside/22,000 g atoms of protein and therefore that four saccharides are bound by the tetrameric molecule. Tn-Con A and native concanavalin A competed for the same receptors on the lymphocyte surface. Moreover, Tn-Con A was mitogenic for both mouse and human lymphocytes with dose-response curves similar to those of the native lectin. All of these results indicate that tryptic hydrolysis of concanavalin A produces a fragmented molecule retaining the saccharide-binding, subunit association, and mitogenic capacity of the native protein.

Amino Acids↗
PubMed1978

Binding and functional properties of concanavalin A and its derivatives. III. Interactions with indoleacetic acid and other hydrophobic ligands.

The binding of concanavalin A to various structures via hydrophobic interactions has been studied using a variety of physicochemical assays. It was found that concanavalin A binds to nonpolar compounds such as the plant auxin beta-indoleacetic acid and its structural analogue tryptophan and that this binding is independent of the saccharide-binding activity normally associated with the lectin. The results of equilibrium dialysis experiments on the binding of beta-indoleacetic acid were consistent with the presence of a single weak binding site per subunit of protein, having an association constant of about 7 X 10(2) M-1. Competition experiments using various nonpolar compounds such as o-iodobenzoic acid suggested that this hydrophobic binding site is located in the same cavity which binds the iodine-containing ligand as shown by x-ray crystallography. Concanavalin A also binds to lipid vesicles composed of dipalmitoylphosphatidylcholine or 12-O-tetradecanoyl phorbol-13-O-acetate. This binding to lipid membranes raises the possibility that the synergistic effects of concanavalin A and tetradecanoyl phorbol acetate on lymphocyte mitogenesis may be due in part to an interaction between lectin and the phorbol ester.

Concanavalin A↗
PubMed1978

Serum IgE and IgG antibody activity against Aspergillus fumigatus as a diagnostic aid in allergic bronchopulmonary aspergillosis.

Serum IgE and IgG antibody activity against Aspergillus fumigatus was measured in 3 groups of subjects by 2 different immunologic methods. Group A consisted of 23 patients with allergic bronchopulmonary aspergillosis (ABPA). Group B was composed of 19 patients with extrinsic asthma who had marked immediate type skin reactivity to A. fumigatus (prick skin test, 3 or 4+) but no other manifestation of ABPA. Group C, the control group, was composed of 12 healthy subjects. Two immunological methods, including a solid-phase polystyrene tube radioimmunoassay and an iodine-125-labeled, A. fumigatus antigen radioimmunoassay, were used to study each patient's serum sample, so as to demonstrate IgE antibody activity against A. fumigatus (IgE-Af) and IgG antibody activity against A. fumigatus (IgG-Af). Both IgE-Af and IgG-Af were significantly greater among patients in Group A than among those in Group B and Group C, as measured by both methods (P is less than 0.001). The results of this study suggest that either method can be used as a diagnostic aid for ABPA. These methods may provide a laboratory test permitting diagnosis of ABPA in its early stages before bronchial or pulmonary destruction occurs.

Aspergillosis↗
PubMed1976

Formation of hybrid concanavalin A molecules by subunit exchange.

Mixing of native concanavalin A (Con A) and its dimeric succinylated derivative (succinyl-Con A) in glycine-HCl buffer, pH 4.5, resulted in the formation of a new chemical species that could be separated as a unique fraction by DEAE-cellulose chromatography or by gel electrophoresis. The molecular weight of this new component, which contained the subunits (Mr= 26,000) of native Con A and its succinyl derivative in equimolar amounts, was 50,000 at both pH 5 and pH 7. These data suggest that subunit exchange between 2 chemically distinct Con A molecules yields a hybrid molecule consisting of one protomer of native Con A and one protomer of succinyl-Con A. Similar exchange reactions and hybrid molecules were also observed after mixing acetyl-Con A and succinyl-Con A. These procedures provide several new chemical variants of the Con A molecule that may be useful for the analysis of lectin-cell surface interactions.

Binding Sites↗
PubMed1976

Monovalent derivatives of concanavalin A.

Monovalent dimers of concanavalin A (Con A) have been prepared by a combination of succinylation and photoaffinity labeling. Partial derivatization of native Con A using the photoaffinity label, p-azidophenyl-alpha-D-mannopyranoside, followed by affinity chromatography yielded a fraction that consisted of dimers with a single saccharide-binding site at pH 5. These monovalent dimers formed divalent tetramers at pH 7. In order to achieve a monovalent dimer at this pH, the divalent tetramers were succinylated by previously developed methods. Ultracentrifugation, equilibrium dialysis, and chromatographic experiments indicated that the resultant preparations consisted mainly of monovalent dimers which showed subunit exchange to yield about 15% divalent dimers after 12 hr at physiological pH. Freshly prepared material failed to agglutinate sheep erythrocytes at concentrations 500-fold higher than native tetravalent Con A. In addition, they showed saturating dose-response curves of mitogenic stimulation of mouse splenic lymphocytes. These curves resembled those of divalent succinyl-Con A but not those of the native molecule. Further development of methods for preparing stable monovalent derivatives of Con A should allow a refined analysis of the effects of lectin valence at the cell surface.

Affinity Labels↗
PubMed1976

Initiation of replication in chromosomal DNA induced by extracts from proliferating cells.

Addition of an extract prepared from a proliferating cell line to nuclei isolated from resting tissues such as frog liver and spleen resulted in the stimulation of DNA synthesis as assayed by [3H]dTTP incorporation. This stimulated incorporation of [3H]dTTP required ATP and depended on Mg2+ and deoxynucleoside triphosphates. Pulse-chase experiments showed that the synthesis of DNA in this system was discontinuous, resulting in the appearance of approximately 4S fragments and their ligation to yield higher molecular weight DNA. In addition, electron microscopic analysis of the DNA molecules from the reaction mixture showed that the frequency of replication "eyes" in the extract-stimulated reaction was 10-fold higher than that observed in controls. All of these results strongly suggest that the extract stimulated initiation of DNA replication in the chromatin of normally resting cells. Preliminary characterization by dialysis, heating, and enzyme treatments indicated that the activity is associated with one or more proteins of high molecular weight (greater than 50,000). Comparison of the levels of stimulatory activity in extracts from various mammalian and avian sources showed that the activity was present in cells proliferating either in vivo or in tissue culture. In contrast, extracts from normally resting tissues and cells had no activity. The level of activity present did not appear to be directly related to the levels of DNA polymerase. These results suggest a use for this system in studying regulation of the initiation of DNA synthesis and control of the various phases of the cell cycle.

Adenosine Triphosphate↗
PubMed1975

Antibodies reactive with cell surface carbohydrates.

Normal and immune sera from various animal species were fractionated on columns of Sepharose covalently coupled with the glycoprotein fetuin. Elution of the material bound to fetuin yielded low but reproducible amounts of protein, ranging from 0.02 to 0.2% of the protein mass of the input sera. This material has been identified by immunoelectrophoresis in agar and by zone electrophoresis on cellulose acetate as immunoglobulin. The Ig fractions bound and agglutinated erythrocytes of various species, and also bound to cells from various mouse tissues including heart, kidney, thymus, and spleen. In all cases, the binding was inhibited by glycoproteins such as fetuin and thyroglobulin, by a glycopeptide isolated from fetuin, and by some bacterial lipopolysaccharides. When the binding of these Ig fractions to mouse splenocytes was tested in the presence of 17 saccharides, no inhibition of binding was observed except by sialic acid, D-galactose, N-acetyl-D-glucosamine, and D-mannose, all of which showed partial inhibition. Inasmuch as these four saccharides are present on the carbohydrate moiety of fetuin, the results suggest that the isolated material is a carbohydrate-specific Ig (CS-Ig) fraction of serum capable of binding to the carbohydrate portion of cell surface receptors and glycoproteins. When bound to lymphocytes, these CS-Ig molecules induced redistribution (patching and capping) of cell surface receptors. Moreover, the CS-Ig fractions from chicken and rabbit sera were weakly mitogenic for mouse splenic lymphocytes. CS-Ig fractions are useful new reagents for studying glycoproteins and the interactions and activities of cell surface carbohydrates.

Agglutination↗
PubMed1975

Modulation of lymphocyte mitogenesis.

Comparisons of the stimulation of normal lymphocytes and lymphoma cells by tetrameric concanavalin a (Con ta) and dimeric succinyl-Con A suggest that both stimulatory and inhibitory signals operate to modulate mitogenesis. Synergistic effects can be obtained for the stimulatory event using lectins, phorbol esters, and calcium ionophores, all of which are independently mitogenic for lymphocytes. The inhibitory effects of high doses of Con A could be mimicked by the simultaneous addition of the phorbol ester and Con A under conditions in which both reagents are optimally mitogenic when used alone. No inhibition of stimulation was found, however, when succinyl-Con A was used with phorbol ester under the same conditions. Moreover, when lymphocytes were cultured with Con A in the presence of succinyl-Con A, the inhibitory effect of the native lectin was seen at lower doses than in the absence of the derivative. These observations suggest that the stimulatory and inhibitory portions of the dose-response curve can be manipulated independently and may be mediated by two distinct signals. It is likely the signal for the inhibition of cell proliferation is regulated by the same cell surface modulating assembly that controls the mobility of cell surface receptors.

Animals↗