Search PubMed⌕ Search

Biomedical subjects

B W Patterson

Publications and source records attributed to B W Patterson.

47 records · Page 3Linked to original sources
PubMed1985

Immune complex hyperlipidemia induced by an apolipoprotein-reactive immunoglobulin A paraprotein from a patient with multiple myeloma. Characterization of this immunoglobulin.

An antibodylike paraprotein has been isolated from a patient with multiple myeloma and autoimmune hyperlipoproteinemia. The paraprotein bound to apolipoprotein B (apo B)-containing lipoproteins that formed macromolecular aggregates, and globules thought to be aggregated complexes of lipoproteins and reactive immunoglobulins were observed circulating within the retinal blood vessels of this patient. This binding specificity permitted purification of the paraprotein from both the agglutinated immune complexes and from the plasma. The protein is an IgA, kappa-immunoglobulin which exists primarily in a polymeric state. Capillary immunoprecipitation demonstrated reactivity with very low density lipoproteins (VLDL) and low density proteins (LDL), but not with high density lipoproteins (HDL). Delipidated apo B and apo E, but not apo A or apo C, formed precipitates with this immunoglobulin. In using a radioimmunoassay format, the affinity of the immunoglobulin was greatest for VLDL and decreases sequentially for intermediate density lipoproteins and LDL. No binding occurred with a dispersion of LDL lipids or with HDL. Deglycosylation did not change the binding to LDL. The apolipoproteins B and E bound with similar affinity, but no binding occurred with apo A-I or apo A-II. Weak binding appeared to occur with apo C. This paraprotein immunoprecipitated apo B-containing lipoproteins from all classes of vertebrates tested. Displacement of the lipids of LDL by Triton X-100 resulted in the formation of an apo B-Triton complex which, however, did not bind to the immunoglobulin; apparently the binding site on apo B was lost. Upon enzymatic digestion with the IgA-specific protease from Streptococcus sanguis the immunoglobulin was cleaved into Fc and Fab fragments, and the binding of LDL occurred only with the latter, consistent with the behavior of an immunoglobulin. The immunoreactivity of this paraprotein with apo B and apo E raises the interesting possibility that it may be binding to a site on these apolipoproteins which is reactive with the apo B, E receptor of the plasma membrane, a site which is conserved throughout the vertebrate phylum.

Aged↗
PubMed1984

A method for the measurement of the sedimentation coefficient and molecular weight of microgram quantities of proteins in 6 M guanidine hydrochloride.

A technique has been perfected for measuring the sedimentation coefficient of microgram quantities of a reduced protein in 6 M guanidine hydrochloride. The protein is sedimented through a gradient of 5-8 M guanidine-HCl in the presence of dithiothreitol in a SW 50.1 swinging-bucket rotor. Run conditions are calibrated by a simultaneous measurement using a single reference protein. Thus, the need for running a calibration curve involving several standard proteins simultaneously with a sample is eliminated. Because of the trace quantity of protein used, the technique yields an estimate of the sedimentation coefficient at zero concentration (s0) directly without extrapolation. Since s0 is a function of the molecular weight of a reduced protein in this solvent, the method also allows an estimate of the subunit molecular weight of the protein. The results of the application of the method to known proteins are reported.

Centrifugation, Density Gradient↗
PubMed1984

Structural studies on apolipoprotein B: controllable heterogeneity of the complex formed with the surfactant, Triton X-100.

Apolipoprotein B complexed with Triton X-100 (T-ApoB) has been isolated from human low density lipoprotein (LDL). Preparations are heterogeneous when analyzed by sedimentation velocity, with a major 12 S species and minor 17 S species present. The 12 S T-ApoB complex possesses a molecular weight of 880,000 containing 400,000 daltons of protein. Hydrodynamic measurements on this complex are consistent with a prolate ellipsoid model having an axial ratio of 13:1 and 0.22 g/g of bound water. Heterogeneity results from the irreversible aggregation of 12 S complexes into discrete 17 S and faster sedimenting components. A significant finding is that three determinants of this T-apoB heterogeneity could be elucidated and controlled. First, the initial state of aggregation is mainly influenced by the technique by which Triton and LDL are mixed. Second, once isolated, T-ApoB complexes slowly but spontaneously undergo further aggregation at 4 degrees C; the rate and extent of aggregation is enhanced remarkably with increasing temperature. Finally, reagents that unfold and expose protein structure (perchlorate, thiocyanate, and reducing reagents) lead to increased aggregation. The ability to control heterogeneity carries important implications for other studies concerning interactions of apoB with surfactants and lipids.

Apolipoproteins B↗
PubMed1983

A comparative study of enzymatic digestion profiles of apolipoprotein B from four human subjects.

A methodological approach for comparative structural study of apolipoprotein B has been developed. Low-density lipoproteins from four human subjects were digested in three separate enzyme systems, utilizing trypsin, chymotrypsin and Staphylococcus aureus protease V8, each in the presence of 1% sodium dodecyl sulfate. The peptides were separated by electrophoresis on polyacrylamide gels in SDS; the stained gels were scanned spectrophotometrically to produce characteristic profiles. Comparison of the profiles revealed good reproducibility and a high degree of similarity among the different subjects. Of the four subjects studied, one subject had one apparent difference in the tryptic digest profile and also in the S. aureus protease V8 digest profile. The structural significance of these variations can be evaluated only after a larger number of subjects, including those presented here, have been examined; this study is now in preparation.

Apolipoproteins↗
PubMed1980

Bovine apolipoproteins C. I. Isolation and spectroscopic investigations of the phospholipid binding properties.

Seven low-molecular weight proteins of the C class of apolipoproteins have been isolated from bovine serum high density lipoprotein. Amino acid analysis has shown five of these to be equivalent to the apolipoproteins previously described (Lim, C.T. and Scanu, A.M. (1976) Artery 2, 483-496). A spectroscopic examination of these proteins in the presence of increasing amounts of L-alpha-dimyristoyl phosphatidylcholine single-bilayer vesicles indicates that all bovine apolipoproteins C exhibit changes in secondary and tertiary structure as shown by intrinsic fluorescence intensity, wavelength, and polarization changes, and increases in alpha-helical content as seen by circular dichroism. Evidence is presented to show that bovine apolipoproteins C, like all human apolipoproteins of the A and C classes, can cause phospholipid multilamellar liposomes to disrupt and/or rearrange into a smaller complex which scatters less light. This paper details the screening of the bovine apolipoproteins for their phospholipid binding properties, whereas the following paper will examine the nature of their complexes with phospholipid in more detail. Together, these papers represent the first investigation of protein-lipid interactions involving any nonhuman apolipoproteins C.

Animals↗
PubMed1980

Bovine apolipoproteins C. II. Isolation and partial physicochemical characterization of complexes with L-alpha-dimyristoyl phosphatidylcholine.

Complexes were made between L-alpha-dimyristoyl phosphatidylcholine (DMPC) and four of the seven bovine apolipoproteins C described in the preceding paper (Patterson, B.W. and Jonas, A. (1980) Biochim. Biophys, Acta 619, 572-586). Reaction mixtures were fractionated by gel filtration chromatography and isopycnic density gradient ultracentrifugation. Selected complexes were further analyzed by sedimentation equilibrium ultracentrifugation and examined for phospholipid bilayer phase transition properties as reported by the fluorescence polarization of a lipophilic probe. Two bovine apolipoproteins C (D2, D3) were able to form complexes with DMPC of virtually the same size, stoichiometry, and density over a wide range of initial lipid/protein molar ratios (200 : 1 to 10 : 1). At very high initial molar ratios (200 : 1 and 100: 1), an additional lipid-enriched complex was formed with these apolipoproteins. Complexes made with D4 were less discrete, having a size, stoichiometry, and density dependent on the initial lipid : protein ratios used. Isolated complexes were smaller than intact DMPC vesicles, representing a break-down product of vesicular structure. The sizes (molecular weights around 2-3 x 10(5)), hydrated densities (1.06-1.12 g/ml), and weight percentage protein compositions (30-40%) of bovine C apolipoprotein-DMPC complexes are comparable to the corresponding parameters for intact bovine HDL. Isolated bovine C apolipoprotein-DMPC complexes retain some phospholipid bilayer structure as indicated by their phase transition behavior. However, the phase transition is considerably broadened and shifted to a higher temperature in the complexes compared to pure lipid. The results obtained are comparable to the phospholipid binding properties of human C apolipoproteins and are consistent with various oblate ellipsoidal models suggested for apolipoprotein-DMPC complexes.

Animals↗
PubMed1977

Physical properties of isolated complexes of human and bovine A-I apolipoproteins with L-alpha-dimyristoyl phosphatidylcholine.

Human or bovine A-I apolipoproteins in solution form complexes with sonicated L-alpha-dimirystoyl phosphatidylcholine at 23 and 37 degrees, but not at 8 degrees, suggesting a strong dependence of the interaction on the physical state of the lipid (phase transition temperature 23 degrees). Complexes were isolated by gel filtration on a Sepharose 4B column and were subsequently analyzed for protein and lipid content, molecular weight, and physical state of the lipid portion. The average stoichiometry of all complexes, regardless of the initial concentrations or ratios of protein and lipid, was constant: 90 +/- 20 mol of phospholipid/mol of protein monomer, suggesting a highly cooperative interaction. Sedimentation equilibrium experiments indicated homogeneous macromolecular preparations and gave molecular weights around 235,000 (+/- 15%) for the complexes, with the human and bovine apo-A-I proteins contributing 77,000 (+/- 10%), i.e. about three protein subunits per complex. The lipid portion of the complexes retained some characteristics of a bilayer: it had a broad phase transition with a midpoint at 25.5 degrees as reported by the fluorescence polarization of the lipophilic probe diphenylhexatriene. Above the phase transition temperature the mobility of the phospholipids in the complexes with both apo-A-I proteins was considerably decreased relative to the pure L-alpha-dimyristoyl phosphatidylcholine dispersion; below the phase transition temperature the opposite was true, i.e. the protein fluidized the lipids. The results indicate that apol-A-I proteins interact stoichiometrically with L-alpha-dimyristoyl phosphatidylcholine vesicles above the gel to liquid-crystalline transition temperature of the lipid, promoting the destruction of vesicles and the formation of well defined particles of the general size of high density serum lipoproteins.

Animals↗
PubMedDate not supplied

Alcoholism and family history of alcoholism: effects on visual and auditory event-related potentials.

In a dual-modality paradigm, visual and auditory event-related potentials were elicited in 40 alcoholic men and 30 controls, equated with the alcoholics on age and education. Half of each group had first-degree relatives who were alcoholic (family history positive). The amplitude of the visual N1 component was reduced among the alcoholics, but their auditory N1 amplitudes were normal. Average N1 amplitudes were also smaller in the family history positive subjects but this effect was significant only for auditory stimuli. Alcoholics showed reduced average P3 amplitudes to both visual and auditory signals, particularly in the family history positive group. Clearly, stratification by family history is useful for ascertainment of ERP variation among alcoholics. There were no effects on P3 latency. Among several possible explanations of P3 deficits in alcoholics, two are particularly interesting: (1) alcoholics cannot mobilize sufficient processing resources in the service of effortful cognitive functions; (2) alcoholics, being poorly motivated, apply insufficient effort to cognitive tasks. An experiment designed to test these hypotheses is described.

Adult↗