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R Hal Scofield

Publications and source records attributed to R Hal Scofield.

At least 37 records · Page 2Linked to original sources
PubMed2004

Determination of prolidase activity using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

Proline-containing peptides of the X-proline type are cleaved by the dipeptidase prolidase. The classical method of prolidase assay relied on the colorimetric estimation of the liberated proline with ninhydrin using acidic media and heat. This method, however, gave inconsistent results due to the nonspecificity of the ninhydrin color reaction. We report here a method for the detection of the liberated proline using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. Human sera were incubated with a mixture containing the dipeptide glycyl-proline in Tris-HCl supplemented with manganese at 37 degrees C for 24h. The samples were precipitated with trifluoroacetic acid and centrifuged. An aliquot of the supernatant was mixed with an equal volume of ferulic acid solution. An aliquot from this mixture was spotted on a stainless steel mass spectrometry grid and analyzed using MALDI-TOF mass spectrometry. The activity of the enzyme was determined by the complete disappearance of the glycyl-proline peak with the concomitant appearance of the proline peak and can be expressed in terms of the ratio of the area beneath the proline to the area beneath the glycyl-proline peak. Subjects homozygous for prolidase deficiency had a ratio ranging from 0.006 to 0.04 while obligatory heterozygotes had a ratio ranging from around 1.1 to 2.4. Normal subjects had ratios ranging from 9 to 239. Using this method we have unambiguously identified subjects with homozygous or heterozygous prolidase deficiency. In addition to the advantage of rapid sample preparation time, this method is highly specific, reproducible, and sensitive.

Colorimetry↗
PubMed2004

Autoantibodies as predictors of disease.

CONTEXT: Many human diseases are the result of autoimmune attack, presumably related to a loss of tolerance to self. Autoimmune disease can be divided into either organ-specific illnesses, such as thyroid disease, type 1 diabetes, and mysasthenia gravis, or systemic illnesses, such as rheumatoid arthritis and systemic lupus erythematosus. The pathogenesis of autoimmune damage also segregates autoimmune disease in that some diseases or manifestations are mainly induced by autoantibodies. Pathogenesis may be mainly mediated by autoimmune T lymphocytes. Notwithstanding the underlying mechanism of disease, virtually all autoimmune diseases are associated with circulating autoantibodies, which bind self-protein. Furthermore, for many diseases these autoantibodies are found in serum samples many years before disease onset. STARTING POINT: In the past several years a new autoantibody specificity has been identified in the sera of patients with rheumatoid arthritis. These autoantibodies bind citrulline, a post-translational modification of arginine. Markus Nielen and colleagues recently studied the presence of these autoantibodies and rheumatoid factor in blood donors who later developed rheumatoid arthritis (Arthritis Rheum 2004; 50: 380-86). About half the patients were positive for at least autoantibody at a median of 4.5 years before the onset of disease. The negative predictive value of these tests was high, while the positive predictive value was very high. WHERE NEXT? Autoantibodies might not be directly responsible for many of the manifestations of autoimmune disease, but they are markers of future disease in presently healthy individuals. Long-term large studies of outcome are needed to assess the use of assaying autoantibodies for prediction of disease. Such data could lead to intervention trials to prevent autoimmune disease, as are already underway in type 1 diabetes.

Arthritis, Rheumatoid↗
PubMed2004

Genetic knock out of 60kD Ro (or SSA), a common lupus autoantigen, induces lupus.

Systemic lupus erythematosus (SLE) could have the most complicated phenotype and the most diverse genetics of any genetically complex human disease. Recent research shows that genetic ablation of the gene encoding 60kD Ro, a common autoantigen for SLE patients, results in an SLE-like illness in Ro-/- mice. These data add to the expanding cooperation between mouse and human SLE genetic studies and are the first in which ablation of an autoantigen induces an autoimmune disease.

Animals↗
PubMed2004

Interaction of calcium and Ro60: increase of antigenicity.

The structural and functional integrity of the cell is largely maintained by protein-protein interactions. Recently, we demonstrated that multiple antigenic peptides (MAPs) constructed from 60 kDa Ro sequence could be used to show intramolecular and intermolecular protein-protein interaction within the 60 kDa Ro ribonucleoprotein particle. We were interested in understanding the mechanism of this binding and hypothesized that this interaction might be mediated through divalent metal ions. The 60 kDa Ro-MAPs failed to interact with purified 60 kDa Ro in the presence of EDTA or EGTA when analyzed by Ouchterlony or surface plasmon resonance (SPR) analysis. When purified 60 kDa Ro was incubated with various metal ions such as Cu2+, Mg2+, Zn2+ and Ca2+, and analyzed by Ouchterlony or SPR for binding to specific 60 kDa Ro-MAPs only Ca2+ ions significantly increased the binding. It was interesting to note that recombinant 60 kDa Ro formed precipitin lines with Ro-MAPs only in the presence of Ca2+ ions. Anti-Ro60 containing SLE sera bound to recombinant Ro60 strongly when incubated in the presence of Ca2+ ions but not in the absence of Ca2+ ions. Using SPR analysis we also found that native Ro60 binds to La only in the presence of Ca2+. These data imply that Ca2+ induces a more native tertiary structure to recombinant 60 kDa Ro and makes it more antigenic. Thus, the observed intramolecular and intermolecular interactions and antigen-antibody interactions could be Ca2+ ion mediated conformational interactions, and we propose that 60 kDa Ro is a calcium binding protein.

Animals↗
PubMed2004

Mechanized syringe homogenization of human and animal tissues.

Tissue homogenization is a prerequisite to any fractionation schedule. A plethora of hands-on methods are available to homogenize tissues. Here we report a mechanized method for homogenizing animal and human tissues rapidly and easily. The Bio-Mixer 1200 (manufactured by Innovative Products, Inc., Oklahoma City, OK) utilizes the back-and-forth movement of two motor-driven disposable syringes, connected to each other through a three-way stopcock, to homogenize animal or human tissue. Using this method, we were able to homogenize human or mouse tissues (brain, liver, heart, and salivary glands) in 5 min. From sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and a matrix-assisted laser desorption/ionization time-of-flight mass spectrometric enzyme assay for prolidase, we have found that the homogenates obtained were as good or even better than that obtained used a manual glass-on-Teflon (DuPont, Wilmington, DE) homogenization protocol (all-glass tube and Teflon pestle). Use of the Bio-Mixer 1200 to homogenize animal or human tissue precludes the need to stay in the cold room as is the case with the other hands-on homogenization methods available, in addition to freeing up time for other experiments.

Animals↗
PubMed2004

A candidate region on 11p13 for systemic lupus erythematosus: a linkage identified in African-American families.

Systemic Lupus Erythematosus (SLE), a chronic, complex disease, is the prototype for systemic human autoimmune diseases. Although environmental factors are crucial in triggering the condition, twin and family studies, as well as genetic linkage and association studies, have established its strong genetic predisposition. During the past few years, there has been considerable interest in identifying genomic segments linked to SLE through either a whole genome scan or a candidate gene approach. The discoid lupus erythematosus (DLE) skin lesion is one of the major, and discriminating, manifestations in SLE, especially in African American patients. In this study we have identified 58 multiplex families--27 African American, 26 European American, and 5 others--where at least one SLE patient is also reported to be afflicted with DLE. These families were chosen from the collection of families that are part of our ongoing linkage study for SLE. A genome-wide parametric and nonparametric linkage analysis was conducted with 320 markers. Significant evidence of linkage was identified in only one chromosomal location, 11p13, in the African American families. The maximum 2-point linkage was 5.6 in these pedigrees, obtained at a marker located 47 CM away from the pterminal end of chromosome 11. The peak multipoint LOD score of 4.6 was obtained very nearby. The segregation of this gene suggests dominant inheritance. These results reveal an important genetic effect related to discoid rash at 11p13 in African Americans with SLE, and demonstrate, through increasing genetic homogeneity, the power of pedigree stratification to detect linkage in complex diseases.

Black or African American↗
PubMed2004

Experimental animal urine collection: a review.

Animal urine collection is a vital part of veterinary practice for ascertaining animal health and in scientific investigations for assessing the results of experimental manipulations. Untainted animal urine collection is very challenging, especially with small rodents, and is an almost impossible task under conditions of microgravity. The fundamental aspects of urine collection are: (1) ease of collection, (2) quality of sample, (3) prevention of contamination, (4) severity of procedures used, (5) levels of pain caused to the animal and (6) refinement of methods to reduce stress, pain or distress. This review addresses the collection of urine for qualitative and quantitative purposes from rodents, rabbits, felines, canines, avian species, equines, porcines, ungulates and certain non-human primates, with animal welfare in mind. Special emphasis has been given to rodents, canines and non-human primates, since they are the animals of choice for research purposes. Free catch (voluntary voiding), methods with mild intervention, surgical methods, modified restraint, cage and special requirement methods have been reviewed here. Efforts need to be taken to provide appropriate animal husbandry and to nurture the animals in as natural an environment as possible since experimental results obtained from these research subjects are, to a great extent, dependent upon their well-being. A continuous refinement in the procedures for collecting urine from experimental animals will be the most efficient way of proceeding in obtaining pure urine specimens for obtaining reliable research data.

Animal Husbandry↗
PubMed2004

Mapping the systematic lupus erythematosus susceptibility genes.

Systemic lupus erythematosus (SLE) is a prototype systemic, autoimmune inflammatory disease that can involve virtually any organ or tissue type. The disease has a strong familial tendency but, like most human illness, has a complex pattern of inheritance that is consistent with multiple susceptibility genes as well as environmental risk factors. Association studies have been performed, especially for the major histocompatibility complex on chromosome 6 and for various complement components. Several large familial studies have begun to report results for genetic linkage. Linkage has been established for many genetic intervals. SLE is a complex clinical illness, and investigation of the genetics of the illness based on clinical manifestations revealed linkages not found without consideration of the phenotype of the disease.

Chromosome Mapping↗
PubMed2003

Development of autoantibodies before the clinical onset of systemic lupus erythematosus.

BACKGROUND: Although much is known about the natural history of systemic lupus erythematosus (SLE), the development of SLE autoantibodies before the diagnosis of the disease has not been extensively explored. We investigated the onset and progression of autoantibody development before the clinical diagnosis. METHODS: The Department of Defense Serum Repository contains approximately 30 million specimens prospectively collected from more than 5 million U.S. Armed Forces personnel. We evaluated serum samples obtained from 130 persons before they received a diagnosis of SLE, along with samples from matched controls. RESULTS: In 115 of the 130 patients with SLE (88 percent), at least one SLE autoantibody tested was present before the diagnosis (up to 9.4 years earlier; mean, 3.3 years). Antinuclear antibodies were present in 78 percent (at a dilution of 1:120 or more), anti-double-stranded DNA antibodies in 55 percent, anti-Ro antibodies in 47 percent, anti-La antibodies in 34 percent, anti-Sm antibodies in 32 percent, anti-nuclear ribonucleoprotein antibodies in 26 percent, and antiphospholipid antibodies in 18 percent. Antinuclear, antiphospholipid antibodies, anti-Ro, and anti-La antibodies were present earlier than anti-Sm and anti-nuclear ribonucleoprotein antibodies (a mean of 3.4 years before the diagnosis vs. 1.2 years, P=0.005). Anti-double-stranded DNA antibodies, with a mean onset 2.2 years before the diagnosis, were found later than antinuclear antibodies (P=0.06) and earlier than anti-nuclear ribonucleoprotein antibodies (P=0.005). For many patients, the earliest available serum sample was positive; therefore, these measures of the average time from the first positive antibody test to the diagnosis are underestimates of the time from the development of antibodies to the diagnosis. Of the 130 initial matched controls, 3.8 percent were positive for one or more autoantibodies. CONCLUSIONS: Autoantibodies are typically present many years before the diagnosis of SLE. Furthermore, the appearance of autoantibodies in patients with SLE tends to follow a predictable course, with a progressive accumulation of specific autoantibodies before the onset of SLE, while patients are still asymptomatic.

Antibodies, Antinuclear↗
PubMed2003

Free radical mediated peroxidative damage in systemic lupus erythematosus.

Free radicals and damage caused by these molecular species are implicated in the pathogenesis of a variety of diseases, including autoimmune. Here we have examined oxidative damage, SOD activity and autoantibodies against SOD in systemic lupus erythematosus (SLE), a multifactorial disease with autoantibody production as an universal feature. We found significantly increased amounts of conjugated dienes in the SLE patients compared to normals (mean value of 0.917 vs 0.627, p = 0.0001) and MDA formation (6.96 vs 4.17 nmoles/microl, p = 0.0006) as well as decreased SOD activity. In addition, we found autoantibodies binding SOD by both ELISA and immunoblot. The presence of anti-SOD antibodies was associated with increased free radical damage in SLE patients. Heat inactivated anti-SOD autoantibodies were able to inhibit the activity of the enzyme. We propose that the inhibition of SOD by autoantibodies is, in part, responsible for the increased free radical damage seen in the disease.

Autoantibodies↗
PubMed2003

The genetics of primary Sjögren's syndrome.

Primary Sjögren's syndrome is an autoimmune disease characterized clinically by dryness of the eyes and mouth. The use of different classification criteria for primary Sjögren's syndrome has led to dramatically different estimates of prevalence and incidence. Despite this, several genetic and environmental factors are thought to play a role in the susceptibility to primary Sjögren's syndrome, as is the current conceptual formulation of the pathogenesis of many other autoimmune maladies. Primary Sjögren's syndrome appears a complicated polygenic disorder with many genes interacting with environmental factors. Similar to many other polygenic autoimmune rheumatic diseases, human leukocyte antigen associations have been reported and confirmed. Additionally, other non-human leukocyte antigen candidate genes have been reported to reveal association with primary Sjögren's syndrome, but, in general, these effects are not confirmed. The authors review the human leukocyte antigen and non-human leukocyte antigen genetic associations herewith, knowing that new technologies are providing access to the entire genome for association studies. No doubt a much more comprehensive description of the genetics of this disorder will soon emerge.

Genetic Predisposition to Disease↗
PubMed2002

Thrombocytopenia identifies a severe familial phenotype of systemic lupus erythematosus and reveals genetic linkages at 1q22 and 11p13.

Systemic lupus erythematosus (SLE) is a complicated autoimmune disease with a definite genetic predisposition. Thrombocytopenia predicts severe disease and death in SLE, making the identification of the related genetic risk factors especially important. We selected the 38 pedigrees that had an SLE patient with thrombocytopenia (platelets, < 10 x 10(9)/L [< 100,000/microL]) from a collection of 184 pedigrees multiplex for SLE. Linkages were established at 1q22-23 (maximum logarithm of odds [lod(max)] = 3.71) in the 38 pedigrees and at 11p13 (lod(max) = 5.72) in the 13 African American pedigrees. Nephritis, serositis, neuropsychiatric involvement, autoimmune hemolytic anemia, anti-double-stranded DNA, and antiphospholipid antibody were associated with thrombocytopenia. Other results show that SLE is more severe in the families with a thrombocytopenic SLE patient, whether or not thrombocytopenia in an individual patient is considered. These results are consistent with thrombocytopenia being a component of a severe familial form of SLE and with genes at 1q22-23 and 11p13 contributing to this severe phenotype and to the subsequent high mortality associated with thrombocytopenia in SLE.

Chromosomes, Human, Pair 1↗
PubMed2002

Evidence for a susceptibility gene (SLEH1) on chromosome 11q14 for systemic lupus erythematosus (SLE) families with hemolytic anemia.

Hemolytic anemia is a forme fruste of systemic lupus erythematosus (SLE), being observed months or even years before the onset of other clinical manifestations in some patients. We hypothesized that hemolytic anemia in those SLE-affected patients would identify a group of SLE pedigrees that share a high degree of genetic homogeneity. From 160 multiplex SLE pedigrees, we sought evidence for linkage in 35 (16 African-American, 17 European-American, and 2 Hispanic) who had at least one SLE-affected patient with hemolytic anemia. Significant linkage was present at 11q14 in the 16 African-American pedigrees, yielding a maximum two-point logarithm of odds (LOD) score of 4.5 at D11S2002. The segregation pattern of SLE in these African-American pedigrees suggested a dominant mode of inheritance and, when maximized across penetrance and disease allele frequencies, produced a multipoint LOD of 4.7. Multipoint analysis yielded a multipoint heterogeneity LOD score of 3.6 (alpha = 0.63), again with maximum LOD at D11S2002. Finally, markers typed 7 centimorgans to either side of D11S2002 achieved LOD scores of 3 or better by using the maximized model, supporting linkage to 11q14. Clearly, pedigree ascertainment based on select clinical manifestations is an important tool, capable of revealing otherwise cryptic genetic linkages in complex genetic diseases. Thus, we show strong evidence for an SLE susceptibility gene, SLEH1, near D11S2002 in African-American pedigrees multiplex for SLE that have at least one SLE-affected patient with hemolytic anemia.

Anemia, Hemolytic↗
PubMed2002

Heat-mediated, ultra-rapid electrophoretic transfer of high and low molecular weight proteins to nitrocellulose membranes.

Here, we report an ultra-rapid method for the transfer of high and low molecular weight proteins to nitrocellulose membranes following sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). In this procedure, the electro-transfer was performed with heated (70-75 degrees C) normal transfer buffer from which methanol had been omitted. Complete transfer of high and low molecular weight proteins (a purified protein, molecular weight protein standards and proteins from a human tissue extract) could be carried out in 10 min for a 0.75-mm, 7% SDS-PAGE gel. For 10% and 12.5% gels (0.75 mm), the corresponding time was 15 min. In the case of 1.5-mm gels, a complete transfer could be carried out in 20 min for 7%, 10% and 12.5% gels. The permeability of the gel is increased by heat, such that the proteins trapped in the polyacrylamide gel matrix can be easily transferred to the membrane. When the heat-mediated transfer method was compared with a conventional transfer protocol, under similar conditions, we found that the latter method transferred minimal low molecular weight proteins while retaining most of the high molecular weight proteins in the gel. In summary, this procedure is very rapid, avoids the use of methanol and is particularly useful for the transfer of high molecular weight proteins.

Blotting, Western↗