Regina Stevens-Truss

Vertical and Horizontal Integration of Bioinformatics Education: A Modular, Interdisciplinary Approach

Bioinformatics education for undergraduates has been approached primarily in two ways: introduction of new courses with largely bioinformatics focus or introduction of bioinformatics experiences into existing courses. For small colleges such as Kalamazoo, creation of new courses within an already resource‐stretched setting has not been an option. Furthermore, we believe that a true interdisciplinary science experience would be best served by introduction of bioinformatics modules within existing courses in biology and chemistry and other complementary departments. To that end, with support from the Howard Hughes Medical Institute, we have developed over a dozen independent bioinformatics modules for our students that are incorporated into courses ranging from general chemistry and biology, advanced specialty courses, and classes in complementary disciplines such as computer science, mathematics, and physics. These activities have largely promoted active learning in our classrooms and have enhanced student understanding of course materials. Herein, we describe our program, the activities we have developed, and assessment of our endeavors in this area.

Activities of cobra venom cytotoxins toward heart and leukemic T-cells depend on localized amino acid differences

Several studies have suggested that along the concave surface of cobra venom cytotoxins, a hydrophobic region flanked by positively charged amino acid side-chains, as well as by tyrosine and/or serine/threonine, allows these toxins to depolarize muscle or cause cytolysis. Comparison of biological activities among structurally homologous toxins, however, has revealed significant functional diversity. The objective of the present study was to examine several toxins purified from different cobra venoms with regard to their ability to bind to and kill human T-lymphocytes and rat heart cell myoblasts. The activities observed were then correlated with differences in amino acid residues which occur in restricted regions of the toxins. The absence of an aromatic residue at position 11 (Loop 1) resulted in a lower cytolytic response at every concentration tested. A simple inversion of two residues in the amino acid sequence of toxin Loop 3 selectively impaired heart cell binding and cytolysis, but had no effect on T-cells. Loss of a positively charged residue in the tip of Loop 2 minimally affected binding but significantly reduced cytolysis. Replacement of valine at positions 27 and 32, along with the introduction of a negative charge at the tip of Loop 2, interfered with binding to either cell type and caused a reduction in cytolysis. The results of this study suggest that no one loop or region is solely responsible for the toxins biological activity. However, because the binding and cytolytic sites within these toxins are distinct, it may become possible to develop toxin derivatives in which only selected activities are enhanced.

SEQUENCE DETERMINANTS OF MODIFIED COBRA VENOM NEUROTOXIN WHICH INDUCE IMMUNE RESISTANCE TO EXPERIMENTAL ALLERGIC ENCEPHALOMYELITIS: MOLECULAR MECHANISMS FOR IMMUNOLOGIC ACTION

A nontoxic, iodoacetamide-modified cobratoxin derivative (CAM-NTX) induced resistance to experimental allergic encephalomyelitis (EAE) in guinea pigs. Resistance was retained after trypsin digestion and shown to reside in N-terminal and central peptides of CAM-NTX. A similarly modified protein cardiotoxin (CAM-CTX), representative of proteins homologous with cobratoxin, was not immunosuppressive. Depressed clinical symptoms in EAE-resistant animals correlated with reduced lymphocytic infiltration of the brain. Antibody to myelin basic protein (MBP) was reduced in immunosuppressed animals. The immunoinhibitory determinants in CAM-NTX may mimic immune response suppressor proteins (SIRS-alpha 7) and the EAE-resistance region of MBP.

In-Line Affinity Chromatographic Removal of Specific Antibody from Rabbits with Experimental Myasthenia Gravis as A Prelude to Immunotherapy

Myasthenia gravis is an autoimmune disease in which antibodies are produced against ones acetylcholine receptors, resulting in complement-mediated membrane destruction and internalization of antibody-receptor complexes. Symptoms range from weakening of extraocular muscles to severe impairment of movement and breathing. Prior to administering a therapeutic agent to eliminate antibody-producing lymphocytes, it will be necessary to remove specific antibody from the circulation. This process was investigated in an animal model of ex vivo specific immunoadsorption using awake, conscious rabbits. Following arterial blood separation, plasma was pumped upward through an affinity column containing covalently-bound acetylcholine receptor. Treated plasma was returned to the rabbit. Within a one-hour ex vivo procedure, specific antibody levels could be lowered from 16.2 ng/ml to less than 0.6 ng/ml, a reduction of more than 95%. By washing the column, at least four exchanges could be performed before specific antibody removal significantly diminished. The effects of specific antibody removal upon muscle function varied among individual rabbits, but if symptoms were not severe following passive transfer of purified monoclonal antibody to induce myasthenia, removal of 60% of the total specific antibody resulted in clinical improvement, as monitored by an animals response to gallamine triethiodide.