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R E Benson

Publications and source records attributed to R E Benson.

At least 19 recordsLinked to original sources
PubMed1992

A multispecies enzyme-linked immunosorbent assay for von Willebrand's factor.

A modified double-sandwich enzyme-linked immunosorbent assay (ELISA), which was developed for human and canine von Willebrand's factor (vWF), was adapted for quantitation of vWF in other species. In addition to human and dog plasmas, 12 other mammalian plasmas that were surveyed exhibited significant cross-species reactivity with antibodies specific for canine vWF or monoclonal antibodies against porcine or bovine vWF. Mixed combinations of monoclonal antibodies and various polyclonal antibodies were also used as sandwich or capture antibodies. The ability of this multispecies ELISA to detect less than 0.002 U of vWF per milliliter of plasma in a large number of species enhances its utility for both research and clinical diagnostic applications. A quantitative assay for rabbit vWF, which exhibits poor cross-species reactivity with most antibodies, was constructed with anti-porcine monoclonal antibody W1-5 and goat-anti-canine vWF as capture and sandwich antibodies, respectively. The same conjugate antibody configuration was used to visualize rabbit vWF multimers by immunoblotting. Specificity of the assay for vWF in human, dog, pig, and horse plasmas was confirmed by use of species-specific vWF-deficient plasmas. In other species, for which vWD plasmas were not available, ELISA specificity for vWF was demonstrated by recovery of greater than 75% of the ELISA-reactive antigen coincident with vWF multimers in the high-molecular-weight (greater than 500 kd) fractions of purified plasmas. This multispecies ELISA permits, for the first time, the measurement of vWF in a variety of mammals for which species-specific immunologic reagents do not currently exist. The results also suggest that certain vWF epitopes have been highly conserved among phylogenetically diverse species.

Animals↗
PubMed1991

Bleeding disorder (von Willebrand disease) in a quarter horse.

Bleeding diathesis in a Quarter Horse filly was caused by von Willebrand disease. Hemorrhage occurred mainly from mucosal surfaces and after trauma. Quantitative and qualitative measurements of plasma von Willebrand factor (vWF) documented a specific deficiency of vWF high molecular weight multimers, and concurrently greater than expected deficiency of vWF activity relative to vWF concentration. These findings are characteristic of type-II von Willebrand disease in human beings. Application of vWF assays used in human and small animal medicine now permits evaluation of vWF and diagnosis of von Willebrand disease in horses with bleeding disorders.

Animals↗
PubMed1991

A sensitive immunoassay for von Willebrand factor.

We have developed an ELISA specific for canine von Willebrand factor antigen (vWF:Ag) that also strongly reacts with the VWF:Ag of humans and many other vertebrates. This assay was designed to avoid the use of immunoreagents of human origin, however, commercially available antibodies to human vWF:Ag may also be used. von Willebrand factor (vWF) was quantitated using a modified double-sandwich ELISA with polyclonal antibodies specific for canine vWF:Ag. The assay was as sensitive for measuring canine vWF:Ag as previously published immuno-radiometric assays and the most sensitive ELISA for human vWF:Ag. Employing commercially available antibodies to human vWF:Ag in the same double-sandwich configuration, the lower limit of detection for human vWF:Ag was 4.8 x 10(-6) units/ml, lower by a factor of ten than previously reported ELISAs. In addition, a wide range of vWF:Ag levels can be determined with just a single plasma dilution. The assay readily distinguishes type III von Willebrand disease from other types of von Willebrand disease having very low levels of vWF. This vWF ELISA can be used to evaluate large numbers of plasma samples simultaneously and is therefore well-suited for large-scale screening programs.

Animals↗
PubMed1986

Conformational changes in von Willebrand's factor protein: effects on the binding of factor VIII-coagulant.

The effects of conformational changes in purified canine von Willebrand's factor (VWF) were investigated to explore the relationship between its factor VIII-related antigen (VIII:AG) and ristocetin cofactor (RCoF) properties and the factor VIII-coagulant (VIII:C) binding site(s). Binding of VIII:C from canine von Willebrand's disease (VWD) plasma by VWF was used to measure the combining reaction of these proteins. The VWF was denatured to varying degrees by exposure to temperature and pH extremes, low ionic strength, and 6 M urea. Various treatments resulted in three types of change: elimination of RCoF, VIIIR:Ag, and VIII:C binding, removal of RCoF activity alone; or elimination of RCoF and retarded elution of VIII:Ag and VIII:C. As long as VIIIR:Ag reactivity was maintained, binding of VIII:C could be demonstrated; but in the absence of VIIIR:Ag, neither RCoF activity nor VIII:C binding remained. These results suggest that VIII:C binding and RCoF sites are separate on VWF and that interaction between VIII:C and VWF is possible even after significant structural changes occur in VWF. Furthermore, RCoF is more vulnerable to denaturation than the antigenic site. The spectrum of conformational changes that affect the properties of VWF may parallel the various recognized subtypes of VWD.

Animals↗
PubMed1986

Assessing the specificity of anti-canine-factor VIII-related antigen.

Antibodies to canine factor VIII-related antigen should be monospecific to accurately study this protein's location in tissue and its structure. Because no uniformly accepted standard for monospecificity exists for anti-factor VIII-related antigen, we have compared the sensitivities of three common evaluation techniques--immunodiffusion, immunoelectrophoresis, and crossed immunoelectrophoresis. Unabsorbed rabbit anti-canine factor VIII-related antigen appeared monospecific against whole plasma by all three methods; however, multiple specificities were recognized against a plasma cryoconcentrate. These results demonstrate the insensitivity of the techniques under certain conditions, which can lead to erroneous interpretation of data.

Animals↗
PubMed1984

A practical technique for preparation of antiserum to canine factor VIII-related antigen.

Identification and measurement of canine factor VIII-related antigen (VIIIR:Ag) has many clinical and research applications, including differential diagnosis of hemophilia A and von Willebrand's disease, use as a marker for specific cell types, and elucidation of the structure of this factor VIII component. We have developed a practical method for producing antibodies to canine VIIIR:Ag that uses 2% agarose filtration for purification and identifies the antigen by correlation with the elution of the peak A280 fraction in the void volume. Antisera for electroimmunoassay (EIA) can be produced in less than four weeks from simple starting materials and with commonly available laboratory equipment. This technique would be useful for either clinical veterinary or comparative research laboratories.

Animals↗
PubMed1983

Efficiency and precision of electroimmunoassay for canine factor VIII-related antigen.

Factors that improved the efficiency, precision, and sensitivity of the electroimmunoassay for canine factor VIII-related antigen were investigated. These included rapid electrophoresis, increased rocket heights, deletion of the gel-washing step, and doubling of the sample capacity per plate. The modified assay was reliable and accurate, could be completed within 3 hours, and permitted twice as many determinations. Other experimental variables that affected the assay were the type of agarose and sample diluent, storage conditions of samples before assay, source of antibody, and use of 2 mM calcium lactate.

Animals↗
PubMed1981

Binding of low-molecular-weight canine factor VIII coagulant from von Willebrand plasma to canine factor VIII-related antigen.

Plasmas having no detectable factor VIII-related antigen but moderate factor VIII coagulant were obtained from two unrelated dogs homozygous for von Willebrand's disease and with the severe clinical expression of the disease. when these plasmas were gel-filtered in a buffer at physiologic ionic strength, the factor VIII coagulant eluted in the bed volume as a single well-defined peak. Addition of protease inhibitors, including diisopropylfluorophosphate, did not change the elution pattern. Each plasma was then combined individually with plasmas from six different mutants of canine haemophilia, all of which had normal factor VIII-related antigen but no detectable factor VIII coagulant. The factor VIII coagulant elution profile of these combined plasma resembled that of normal canine plasma. Slightly over half of the recovered factor VIII coagulant coeluted in the void volume with the factor VIII-related antigen; the rest eluted as a second, distinct peak of lower molecular weight. These results demonstrated that part of the factor VIII coagulant of the von Willebrand plasmas had bound to the factor VIII-related antigen of the haemophilic plasmas. This finding supports the theory that factor VIII exists as a macromolecular complex of nonidentical components in normal citrated plasma.

Animals↗
PubMed1980

A bleeding disease (von Willebrand's disease) in a Chesapeake Bay Retriever.

A bleeding disease similar to von Willebrand's disease in man was diagnosed in a 6-month-old Chesapeake Bay Retriever with recurrent, protracted gingival hemorrhage that responded rapidly to fresh, whole blood transfusions. The dog had a prolonged bleeding time and low plasma factor VIII coagulant activity (18%). The plasma had no detectable factor VIII-related antigen or von Willebrand factor, as measured by ristocetin-cofactor and polybrene-cofactor activities. The dam of the dog had a plasma factor VIII-related antigen concentration (32%) well below the normal range. The antigen in the sire's plasma was at the low end of the normal range, as was the polybrene-cofactor of both the sire and the dam. These data suggested an inherited basis for von Willebrand's disease in this dog.

Animals↗
PubMed1980

Measurement of canine von Willebrand factor using ristocetin and Polybrene. Diagnosis of canine von Willebrand's disease.

Dogs with VWD provide useful models for the study of the factor VIII complex. However, the study of canine VIIIR:WF has been hampered by the lack of a routine plasma assay for canine RCF, an activity that is usually used as a measure of VIIIR:WF. This study shows that canine plasma can be assayed for RCF with a macroscopic tilt-tube method using formalin-fixed human platelets, ristocetin, and extra canine albumin (5.0 mg/ml) to prevent plasma precipitation. An assay was also developed for canine plasma PBCF, an activity that is closely related to RCF. In 45 normal canine plasmas, VIII:C was not correlated with RCF, PBCF, or VIIIR:AG. However, RCF, PBCF, and VIIIR:AG were well correlated with each other. In 26 canine VWD plasmas, VIII:C was frequently normal, whereas VIIIR:AG, RCF, and PBCF were almost always deficient. The patterns of VIIIR:AG, RCF, and PBCF deficiencies in the canine VWD plasmas suggested that some canine breeds have a "classic" form of VWD whereas other breeds have "variant" forms of disease.

Animals↗
PubMed1976

Mental health centers and the criminal justice system.

Through questionnaires, interviews, and site visits, the authors undertook to ascertain to what extent the 26 community mental health centers in Kansas were contributing to the resolution of problems that concern the criminal justice system. They found that in all large communities some reciprocal programs have developed between the two systems, but meaningful collaboration is rare in small communities. Juvenile courts, urban law enforcement agencies, and county probation officers are most receptive to collaborative programs. An evaluation of several effective programs revealed three basic conditions that attribute to their success: an urban community setting, individual initiative by staff from each system, and location of the program within the criminal justice system.

Adolescent↗
PubMed1976

Immunologic characterization of canine factor VIII.

Canine factor VIII (FVIII) preparations isolated from cryoprecipitates by gel chromatography were pooled to provide one batch of antigen for simultaneous immunization of two rabbits and a goat. The goat and rabbit antisera had similar FVIII-neutralizing titers, but the latter had seven to ten times more precipitating titer for FVIII-related antigen (FVIII-RA). Absorption with material low in FVIII had little effect on the precipitating titer of the rabbit antibody, but it abolished the precipitating capacity of the goat antibody and caused a 20% reduction in the neutralizing titer of both antisera. Results obtained in the Laurell assay with the two different antisera were similar. This finding was true whether the FVIII-RA levels were reduced, normal, or elevated, as well as for heat-treated and frozen-thawed plasmas. Both antisera were neutralized by the same canine plasma to a similar extent. Analysis of FVIII concentrates by crossed immunoelectrophoresis suggested that canine FVIII-RA was heterogeneous, with slow-and fast-migrating components. The presence of more than one antigenic site on the FVIII complex was also supported by the disparity between the FVIII-neutralizing and -precipitating titers of goat antiserum and by the demonstration that FVIII-RA, FVIII-neutralizing antigen, and procoagulant activity varied independently.

Animals↗