Biomedical subjects

David R Lee

Publications and source records attributed to David R Lee.

4 recordsLinked to original sources

PubMed2004

Characterization of bovine homologues of granulysin and NK-lysin.

Granulysin and NK-lysin are antimicrobial proteins found in the granules of human and swine cytotoxic lymphocytes. A murine counterpart to granulysin has not been identified to date, indicating the importance of additional models to fully characterize the role of granulysin-like molecules in the immune response to infectious disease. Two partial nucleotide sequences corresponding to the complete functional domain of granulysin and NK-lysin were amplified from bovine PBMC mRNA. Following stimulation with phorbol ester and calcium ionophore, expression of the bovine gene was detected in CD3(+) T cells, CD4(+) T cells, CD8(+) T cells, WC1(+) gammadelta T cells, and PBMC depleted of CD3(+) T cells, but was absent in CD21(+) cells and CD14(+) cells. Intracellular flow cytometry and immunoblotting confirmed the presence of protein corresponding to the bovine granulysin homologue in activated T lymphocytes and PBMC. Synthetic human, bovine, and swine peptides corresponding to the C terminus of helix 2 through helix 3 region of granulysin displayed potent antimicrobial activity against Escherichia coli, Salmonella enteritidis, Staphylococcus aureus, and Mycobacterium bovis bacillus Calmette-Guérin. Human and bovine peptides corresponding to helix 2 displayed antimycobacterial activity against M. bovis bacillus Calmette-Guérin. Expression of the bovine gene was detected in laser microscopy-dissected lymph node lesions from an M. bovis-infected animal. The identification of a biologically active bovine homologue to granulysin demonstrates the potential of the bovine model in characterizing the role of granulysin in the immune response to a variety of infectious agents.

Amino Acid Sequence↗

PubMed2002

Polymorphism at position 97 in MHC class I molecules affects peptide specificity, cell surface stability, and affinity for beta2-microglobulin.

The two mouse MHC class I alleles, L(d) and L(q), share complete amino acid sequence identity except in the alpha2 domain, where they differ at six positions. Despite their similarity, L(q) has a stronger association with beta2-microglobulin (beta2m), is expressed at higher levels on the cell surface, demonstrates an increased cell surface half-life, and has fewer open forms on the cell surface than L(d). To determine the basis for their phenotypic differences, L(d) molecules containing chimeric L(d)-L(q) alpha2 domains were characterized, and these analyses implicated residue 97 (L(d)Trp and L(q)Arg) as the polymorphic site responsible for the disparity in beta2m association between the two alleles. Single substitution analysis at this site (L(d)W97R and L(q)R97W) confirmed this. Furthermore, the L(d)W97R mutant molecule has a longer cell surface half-life than either L(q) or L(d), and fewer open forms of L(d)W97R are observed on the cell surface. In addition, both L(d)W97R and L(q) possess decreased binding affinity for the L(d)-restricted tum(-) P91A(14-22) peptide compared with L(d). Collectively, these results and the known location of Trp(97) in the peptide binding cleft of L(d) strongly suggest that the substitution of Arg for Trp(97) in L(d) alters the peptide binding cleft, increasing its affinity for endogenous peptides, which results in greater cell surface stability and better retention of beta2m. Furthermore, these results imply that Trp(97) plays an important role in the ability of L(d) to efficiently participate in alternative MHC class I Ag presentation pathways.

Alleles↗

PubMed2002

T cell immunity in connective tissue disease patients targets the RNA binding domain of the U1-70kDa small nuclear ribonucleoprotein.

Although the T cell dependence of autoimmune responses in connective tissue diseases has been well established, limited information exists regarding the T cell targeting of self Ags in humans. To characterize the T cell response to a connective tissue disease-associated autoantigen, this study generated T cell clones from patients using a set of peptides encompassing the entire linear sequence of the 70-kDa subunit of U1 snRNP (U1-70kDa) small nuclear ribonucleoprotein. Despite the ability of U1-70kDa to undergo multiple forms of Ag modification that have been correlated with distinct clinical disease phenotypes, a remarkably limited and consistent pattern of T cell targeting of U1-70kDa was observed. All tested T cell clones generated against U1-70kDa were specific for epitopes within the RNA binding domain (RBD) of the protein. High avidity binding of the RBD with U1-RNA was preserved with the disease-associated modified forms of U1-70kDa tested. The high avidity interaction between the U1-RBD on the polypeptide and U1-RNA may be critical in immune targeting of this region in autoimmunity. The T cell autoimmune response to U1-70kDa appears to have less diversity than is seen in the humoral response; and therefore, may be a favorable target for therapeutic intervention.

Alanine↗

PubMedDate not supplied

Circadian and orthostatic blood pressure is abnormal in the carotid sinus syndrome.

The authors' objective was to determine circadian blood pressure behavior and the prevalence of orthostatic hypotension in patients with cardioinhibitory carotid sinus syndrome. A prospective consecutive series of 160 patients (mean age, 72 [65-83]) with recurrent syncope attributed to cardioinhibitory carotid sinus syndrome was recruited. Mean maximal slowing of heart rate was 4.5 seconds (3.0-5.5 seconds) during carotid sinus massage. Patients had cardiovascular assessments, including 24-hour ambulatory blood pressure measurements (recordings every half-hour during daytime, hourly at night) and morning orthostatic blood pressures before pacemaker implants. Ambulatory measurements were compared with those of 98 age- and sex-matched controls. Nocturnal systolic blood pressure (130.0+/-21.0 vs. 122.1+/-16.7 mm Hg; p<0.005), diastolic blood pressure (72.8+/-12.5 vs. 68.7+/-9.7 mm Hg; p<0.005), and heart rate (66.5+/-9.4 vs. 65.2+/-9.7 bpm; p<0.005), were significantly higher in patients and independent of cardiovascular medication, cardiovascular diagnoses, and orthostatic hypotension. Almost one half of carotid sinus syndrome patients also had orthostatic hypotension. Blood pressure behavior is abnormal in patients with carotid sinus syndrome as represented by altered nocturnal blood pressures and high prevalence of orthostatic hypotension.

Aged↗