Biomedical subjects

S E Baker

Publications and source records attributed to S E Baker.

9 recordsLinked to original sources

PubMed1995

Molecular genetic studies of a human epidermal autoantigen (the 180-kD bullous pemphigoid antigen/BP180): identification of functionally important sequences within the BP180 molecule and evidence for an interaction between BP180 and alpha 6 integrin.

The 180-kD bullous pemphigoid autoantigen (BP180) is a component of the hemidesmosome, a cell-matrix connector. This protein is oriented in a type II fashion in the membrane of the hemidesmosome and is a hybrid collagen (classified as type XVII). We have analyzed the fate of various mutant BP180 molecules transfected into several different cell types. A protein, D1, lacking the collagen-like extracellular domains of BP180 polarizes normally in 804G epithelial cells and colocalizes with other hemidesmosomal components in the plane of the basal cell surface. However, deletion of a stretch of 36 amino acids located at the NH2 terminus of D1 induces an apical polarization of the protein (D1-36N) in the cell surface of 804G cells. Deletion of the 27-amino acid noncollagenous extracellular domain that is located immediately after the membrane spanning domain of BP180 results in a failure of D1-27C protein to codistribute with other hemidesmosomal components despite its basal localization in transfected 804G cells. In FG cells, which lack their own BP180, transfected D1 protein localizes with the alpha 6 beta 4 integrin heterodimer. In HT1080 cells, which do not possess BP180 or beta 4 integrin, D1 protein localizes with alpha 6 beta 1 integrin while both the D1-27C and D1-36N proteins do not. Moreover, D1 protein coprecipitates with alpha 6 integrin from extracts of HT1080 transfectants. Taken together, these results suggest that the NH2-terminal domain of BP180 determines polarization of BP180 while the noncollagenous extracellular domain of BP180 stabilizes its interactions with other hemidesmosomal components, such as alpha 6 integrin. Perturbation of this latter domain by human bullous pemphigoid autoantibodies may explain the loss of epidermal cell-dermis attachment that characterizes the BP disease.

Amino Acid Sequence↗

PubMed1995

Determination of pesticide metabolites in human urine using an isotope dilution technique and tandem mass spectrometry.

A method that measures 12 analytes in urine and reflects possible exposure to pesticides was developed. The sample preparation involves enzyme hydrolysis and solvent extraction through the use of laboratory robotics, followed by phase-transfer catalysis derivatization and silica cleanup. Samples are analyzed by capillary gas chromatography and tandem mass spectrometry using an isotope dilution technique with 13C-labeled internal standards. The limit of detection is 1 microgram/L (1 part per billion) for most analytes, and most analytes have a linear response up to 100 micrograms/L. The precision of the method is reflected in the variation observed in quality control materials over 33 months; the variation averaged 17% for these analytes. On the basis of the detectable analyte levels of unspiked urine samples collected from unexposed volunteers, this method can be used to measure the low levels necessary for establishing reference range values of the selected pesticides or metabolites.

Calibration↗

PubMed1995

Murine cytomegalovirus-associated arteritis.

Unique inflammatory lesions affecting the ascending aorta and pulmonary artery of BALB/c and C57BL/6 mice infected with murine cytomegalovirus (MCMV) were identified in a pilot and two subsequent experiments to characterize the potential effect of MCMV infection on diet-induced atherosclerotic lesions. Suckling BALB/c and C57BL/6 mice were inoculated with MCMV and subsequently fed either a commercial mouse diet or a synthetic atherogenic diet from weaning. The three experiments varied with respect to the age of the mice at the time of MCMV inoculation and the dose of virus given. The conditions of MCMV exposure were progressively modified in the three experiments to increase the prevalence of MCMV-associated inflammatory lesions in the pulmonary artery and aorta. In the final experiment, in which suckling mice were inoculated at 9 days of age, MCMV-associated arteritic lesions had an observed prevalence at 8 weeks post-inoculation of 87.5% (7/8) in BALB/c mice on the normal diet and 100% (8/8) in C57BL/6 mice on the normal diet and in both strains on the atherogenic diet. The inflammatory lesions in both vessels were characterized by mononuclear cell infiltrates containing CD3+, CD4+, and CD8+ lymphocytes. The cellular infiltrates were often more intense on the adventitial surface and infiltrated into the overlying tunica media. The intima was infiltrated by mononuclear cell infiltrates that appeared to contain more macrophages and fewer lymphocytes than did the adventitial infiltrates.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1994