Biomedical subjects

S D Warren

Publications and source records attributed to S D Warren.

4 recordsLinked to original sources

PubMed1995

Identification of efficient pentapeptide substrates for the tyrosine kinase pp60c-src.

The development of inhibitors of protein tyrosine kinases (PTKs) is a promising approach to obtaining new therapeutic agents for a variety of diseases, particularly cancer. However, the discovery of peptide-based inhibitors has been hindered by the lack of small peptide substrate sequences (i.e. five residues or less) with which a variety of inhibitor designs could be readily evaluated by replacing the Tyr with natural and unnatural amino acids. These prototypical small peptide inhibitors could then form the basis for designing analogous conformationally constrained, peptide-mimetic or non-peptide inhibitors with improved therapeutic potential. In this study we have identified the best known small peptide substrate for the PTK pp60c-src, which is the parent of the src family of nonreceptor PTKs. This pentapeptide substrate, Ac-Ile-Tyr-Gly-Glu-Phe-NH2, has a Km of 368 microM and Vmax of 1.02 mumol/min/mg when tested utilizing the assay methodology of Budde et al. (Anal. Biochem. 1992, 200, 347-351) after a series of modifications were made to more closely simulate the conditions inside a typical mammalian cell. This substrate was designed from information obtained by Songyang et al. (Nature 1995, 373, 536-539) with a 2.5 billion member combinatorial library of peptide substrates for pp60c-src. A second pentapeptide substrate, Ac-Glu-Asp-Ala-Ile-Tyr-NH2, with a weaker binding affinity (Km = 880 microM) but improved Vmax (1.86 mumol/min/mg), was also identified. This peptide was designed from the pp60c-src autophosphorylation sequence and information obtained by Songyang et al. (Ibid.) and Till et al. (J. Biol. Chem. 1994, 269, 7423-7428) with combinatorial libraries of peptide substrates. These new substrates provide sufficient binding affinities and rates of phosphorylation to be utilized for evaluating the relative effectiveness of various reversible and mechanism-based irreversible inhibitor designs for pp60c-src while appended to easily prepared small peptides.

Adenosine Diphosphate↗

PubMed1993

Cicatricial pemphigoid.

This case of CP is of interest because of its "not-so-benign" course in this patient, its unusual immunofluorescence patterns, and the need for a complex therapeutic regimen to achieve control. This patient had severe ocular; laryngeal, and oropharyngeal involvement leading to visual problems, hoarseness, and marked weight loss and dehydration. He also had anemia thought to be partially related to dapsone use. We believe the side effects of dapsone, combined with fluid retention due to prednisone therapy, contributed to cardiac failure. The diagnosis of CP is usually established by correlation of clinical findings with immunofluorescence studies. However, indirect immunofluorescence may show strong intercellular antibody binding in the epidermis (ie, pemphigus-like antibodies). Treatment alternatives for patients with CP who have adverse reactions to, or no significant benefit from, conventional agents such as dapsone or prednisone may include immunosuppressive agents such as azathioprine or cyclophosphamide. As this case demonstrates, care of patients having CP involves a cooperative effort from a number of different specialties, including dermatology, primary care, ophthalmology, and otolaryngology.

Aged↗

PubMed1990

Improving the tumor retention of radioiodinated antibody: aryl carbohydrate adducts.

Improved methods for attaching radioiodine to monoclonal antibodies have been developed. Ten aryl carbohydrate adducts were synthesized by the reductive amination of a carbohydrate with an aryl amine, using sodium cyanoborohydride as a reducing agent. After purification by chromatography and characterization by nuclear magnetic resonance they were iodinated using the chloramine-T method. Iodinated adducts were activated with cyanuric chloride and incubated with protein at room temperature. The immunoreactivity and avidity of radioiodinated tyramine cellobiose (TCB) labeled antibody were fully preserved when compared to electrophilically radioiodinated antibody. Radioiodinated TCB-and tyramine glucose-labeled monoclonal antibodies showed much greater intracellular retention of radioiodine when compared to electrophilically radioiodinated monoclonal antibodies. Neither radioiodinated tyramine nor radioiodinated TCB had any specific tissue uptake or retention. In mice the retention of radioiodinated TCB labeled anti-Thy-1.1 antibody (1A14) by Thy-1.1-bearing lymphoma cells was 2 times greater than that of chloramine-T labeled 1A14 antibody, whereas the plasma clearance curve and uptake in normal tissues was not changed. This method of radioiodinating monoclonal antibodies increases the retention time of radioiodine in tumor and thus may obviate the problem of intracellular deiodination, a perceived disadvantage of electrophilically iodinated antibodies, with respect to tumor retention of radioactivity.

Animals↗

PubMed1988

Synthesis and radioiodination of tyramine cellobiose for labeling monoclonal antibodies.

A tyramine cellobiose (TCB) adduct was synthesized by the reductive amination of cellobiose by tyramine with a product yield of 78%. The TCB adduct was purified by chromatography and then iodinated using the chloramine-T method. After iodination, the adduct was activated with cyanuric chloride and linked to protein by incubation at room temperature for 2 h. Immunoreactivity and avidity were well maintained compared to electrophilically radioiodinated 1A14 whole antibody. The tumor uptake and retention were strikingly greater with iodinated TCB-antibody compared to that of the conventionally iodinated antibody; whereas, the plasma clearance curve and uptake in other organs were not changed. This method of labeling increases the retention time of radioiodine in tumors and thus extends to iodinated antibodies one of the advantages of indium labels, namely that the isotope is not readily washed out of the tumor after it becomes localized.

Animals↗