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Biomedical subjects

D R Webb

Publications and source records attributed to D R Webb.

At least 109 records · Page 6Linked to original sources
PubMed1984

Assessment of tachyphylaxis following prolonged therapy of asthma with inhaled albuterol aerosol.

Controversy exists concerning possible tachyphylaxis of the acute bronchodilating effect of albuterol, especially with regard to the duration of its acute bronchodilating action. We evaluated 140 patients with bronchial asthma in a prospective double-blind controlled study of possible tachyphylaxis to albuterol aerosol as compared to isoproterenol aerosol. We demonstrated statistically significant tachyphylaxis with regard to duration of acute bronchodilating effect. We believe that this tachyphylaxis is not clinically significant because there was no tachyphylaxis with regard to peak bronchodilating effect and because the duration of bronchodilating effect remains significantly greater, both quantitatively and statistically, when compared to isoproterenol aerosol. Moreover, it appeared that most of the tachyphylaxis was present at four weeks of therapy. There was a small increment of tachyphylaxis after eight weeks of therapy, but no further increase in tachyphylaxis was demonstrated after 13 weeks of inhaled albuterol therapy. We therefore feel that clinically significant tachyphylaxis to inhaled albuterol aerosol must be quite unusual and that chronic therapy with inhaled albuterol aerosol is probably both safe and efficacious for bronchospastic disorders.

Adolescent↗
PubMed1983

Purification and characterization of an L-glutamic acid60-L-alanine30-L-tyrosine10 (GAT)-specific suppressor factor from genetic responder mice.

A hybridoma-derived, GAT-specific suppressor T cell factor (GAT-TsFR) from responder C57BL/10 mice has been purified to apparent chemical homogeneity using reversed phase HPLC techniques. 40 l of starting material yielded approximately 880 micrograms protein with a specific activity of 28.4 X 10(3) S50 U/ng protein representing a purification factor of 4.2 X 10(6). Purified GAT-TsFR is a hydrophobic protein with a minimum molecular weight of 18,000 that is capable of forming biologically active aggregates with molecular weights of 28,000, 64,000 and approximately 84,000 and has a pI of 6.4. GAT-TsFR is a glycoprotein that binds GAT and GT, but not GA, and bears determinants encoded by the I-J subregion of the H-2 complex. This GAT-TsFR derived from an H-2b responder haplotype to GAT is compared with GAT-TsF derived from the nonresponder H-2q haplotype on the basis of biochemical and some serological properties.

Amino Acids↗
PubMed1983

Purification and biochemical analysis of antigen-specific suppressor factors obtained from the supernatant, membrane, or cytosol of a T cell hybridoma.

A suppressor factor (TsF) specific for the synthetic terpolymer L-glutamic acid60-L-alanine30-L-tyrosine 10(GAT) produced by the T cell hybridoma 342B1.11 has been purified to apparent chemical homogeneity. This TsF was found in the cell culture supernatant, was associated with the cell membrane fraction, and was found in the cytosol. The supernatant form of TsF occurs as a single polypeptide chain of 29 to 30 k m.w., which easily forms aggregates of 65 k m.w. The membrane-associated form of TsF exists primarily as 65 k m.w., the cytosol TsF exists as both 65 and 29 to 30 k m.w. Amino acid analysis of each source of TsF shows the identical mole percent of amino acids, suggesting that all forms of TsF are derived from a single peptide of 29-30 k m.w. Analysis of the supernatant TsF by electroblot with the use of the anti-I-Js antisera (H-2s is the haplotype of the spleen cell donor) indicates that the polypeptide bears an I-J determinant, as do other TsF of this type.

Amino Acids↗
PubMed1983

Purification and initial characterization of the lymphokine soluble immune response suppressor.

Two molecular forms of the lymphokine soluble immune response suppressor (SRIS), obtained from serum-free supernatant fluids of a T cell hybridoma producing SIRS, have been purified by a combination of gel filtration and high performance liquid chromatography (HPLC). Supernatant fluids (8 liters) from the hybridoma 393.D2.6 were concentrated and fractionated on Sephadex G-50 in 0.4 M pyridine/0.4 M acetic acid buffer. Active fractions containing approximately 1 X 10(7) units of SIRS activity and 300 mg protein were fractionated further by reverse phase HPLC on a Lichrosorb RP-18 column in a 1.0 M pyridine-0.5 M acetic acid buffer. A stepwise n-propanol gradient reproducibly eluted SIRS activity in the 20% n-propanol fraction. After three chromatography steps on the Lichrosorb RP-18 column, final purification was obtained with an Si-100 diphenyl column by employing the same buffer and elution system. SIRS eluted in the 30% n-propanol fraction as two discrete protein peaks. Purity of SIRS was assessed by SDS-polyacrylamide gel electrophoresis. The two protein peaks from the fractionation on the diphenyl column each exhibited only one band of protein with m.w. of 21,500 and 14,000, respectively. Additional studies of both molecular species of SIRS showed they possessed functional properties identical to those previously described for crude SIRS. Final purification of the 21,500 SIRS species yielded approximately 10 micrograms of protein and 6 X 10(8) units of SIRS activity or 6 X 10(10) units/mg protein; final purification of 14,000 SIRS species yielded approximately 30 micrograms of protein and a similar amount of SIRS activity or 2 X 10(10) units/mg protein.

Cell Line↗
PubMed1982

Cell-free translation of a biologically active, antigen-specific suppressor T cell factor.

In vitro synthesis of an antigen-specific T cell suppressor factor (TsF) has been accomplished by using partially purified poly(A)-containing RNA in a rabbit reticulocyte lysate cell-free translation system. The poly(A)-containing mRNA was isolated from a cloned T cell hybridoma that constitutively produces a TsF specific for the synthetic polypeptide antigen poly-(LGlu60LAla30LTyr10) (GAT). The RNA was fractionated by size and translated in vitro. The 16S RNA fraction stimulated synthesis of a biologically active protein that specifically suppressed both the GAT-specific antibody response by spleen cells in vitro and the proliferation response to GAT by lymph node T cells from GAT-primed mice. Further, the suppressor factor had a binding site for GAT, a determinant encoded by the I subregion of the major histocompatibility complex (MHC), and an apparent Mr 19,000 estimated by functional assays on protein separated by NadodSO4/polyacrylamide gel electrophoresis. These results indicate that virtually no posttranslational modifications (other than proteolytic cleavage) are necessary to obtain biologically active TsF. Hence, the presence of carbohydrate or other chemical groups does not contribute to either the serological properties of GAT-TsF or its biological properties.

Animals↗
PubMed1982

Purification and characterization of a monoclonal T-cell suppressor factor specific for poly(LGlu60LAla30LTyr10).

A monoclonal T-cell-derived suppressor factor specific for the terpolymer poly(LGlu60LAla30LTyr10) produced by the T-cell hybridoma 258 C4.4, was purified to homogeneity. This was accomplished by fractionation of the culture medium by using a combination of affinity chromatography and reverse-phase and ion-exchange high-performance liquid chromatography. The purified factor is composed of a single Mr 24,000 polypeptide chain, and the homogeneous protein maintains the ability to suppress antibody and T-cell proliferative responses to poly(LGlu60LAla30LTyr10) specifically. The specific activity of pure suppressor factor is calculated to be 8 X 10(7) units/micrograms.

Amino Acids↗
PubMed1981

Effect of protein aggregation on murine splenic prostaglandin F2 alpha levels.

Intravenous injection of deaggregated human gamma globulin and deaggregated keyhole limpet hemocyanin into C57Bl/6 mice does not result in an increase in splenic prostaglandin F2 alpha. However, when aggregated human gamma globulin or aggregated keyhole limpet hemocyanin were injected, significant increases in splenic PGF2 alpha were observed. Mice which had been rendered immunologically tolerant to human gamma globulin (HGG) also demonstrated increases in splenic PGF2 alpha and PGE2 5 min after boosting with aggregated HGG with no increases in antibody against HGG. These results imply that the property of protein aggregation will engender increases in splenic prostaglandin levels and that these increases don't appear to affect the tolerant state.

Animals↗
PubMed1981

The effect of prostaglandin metabolism on immunoglobulin and antibody production in naive and educated whole spleen cells.

Addition of prostaglandin E2 or inhibitors of prostaglandin biosynthesis to Mishell-Dutton cultures results in changes of immunoglobulin levels, particularly IgM, secreted into the culture supernatant. These changes in the quantity of immunoglobulin found in the supernatant are minimal in cultures containing naive cells. When BSA educated cells from C57B1/6 immunized mice were cultured, PGE2 was very effective in amplifying the biosynthesis of immunoglobulin when placed in culture in the presence of BSA. Whole spleen cell cultures from C57B1/6 mice immunized with sRBC also had increased immunoglobulin concentrations in culture supernatants upon exposure to PGE2 at culture initiation. However, the addition of sRBC to these cultures did not further increase immunoglobulin production. In all cases indomethacin inhibited the appearance of immunoglobulin into the supernatant by antigen educated cells. This inhibition which may be a result of inhibited immunoglobulin synthesis and not an impairment of transport, could be overcome by the inclusion of PGE2 in the cultures. PGE2 added to cultures containing cells educated against human gamma globulin caused an increase in the quantity of human gamma globulin-specific antibody in the culture supernatant while it had no effect on naive cells. These results indicate that prostaglandin metabolism may exert a greater influence on educated lymphocytes than naive lymphocytes in terms of immunoglobulin secretion and specific antibody production.

Animals↗
PubMed1981

Steroids in allergic disease.

From the experience above, it may be concluded that corticosteroid therapy in allergic disease has become more effective than ever before. The expected variations in usage of new important pharmacologic agents is seen with special clarity in the use of corticosteroids. The wide acclaim for the "miracle drug of the 1950's", which followed penicillin of the 1940's, soon gave away to anguish about side-effects that threatened to abolish its use entirely in the late 1950's. The 1960's brought alternate day therapy for chronic usage and recognition that short term usage was relatively safe. The 1970's saw proliferation of topically active steroids similar to those so important to the practice of Dermatology in the previous decade. Results in treating asthma and nasal diseases have been excellent and extensive research for adverse effects has been largely unrevealing.

Administration, Intranasal↗
PubMed1981

Replication of vesicular stomatitis virus in murine spleen cells: enrichment of the virus-replicating lymphocytes and analysis of replication restriction.

Vesicular stomatitis virus (Indiana strain) will only grow in T lymphocytes which have been stimulated to undergo cell division. Evidence is presented that a considerable enrichment of the vesicular stomatitis virus-replicating T cells may be accomplished in the mouse spleen by passing the spleen cells over glass wool columns. By using this procedure experiments were performed to study the nature of the block in vesicular stomatitis virus replication in unstimulated (nonpermissive) versus mitogen-stimulated (permissive) splenic T cells. The results show that, as is the case in permissive T-cell lines, stimulated normal T cells allow the synthesis of the 42S virion ribonucleic acid.

Animals↗