Significance of levels of specific immunoglobulins to DNA in SLE patients' sera detected by solid phase radioimmunoassay.

A solid phase radioimmunoassay was developed for detecting the quantity of double-stranded and single-stranded DNA antibodies in patients with systemic lupus erythematosus and other connective tissue diseases. The assay system employs a solid support 96-well, flex-vinyl microtiter plate to which bovine methyl albumin is layered, followed by denatured or native calf thymus DNA. A 1:80 dilution of patients' sera was added to respective wells followed by tritiated high affinity anti-IgG, -IgA, or IgM. Denatured DNA (single-stranded DNA) bound to methylated bovine serum albumin had less than 5% reannealment to the double-stranded form and provided a better substrate for Ab binding than double-stranded DNA, producing a linear binding curve. Of 58 patients diagnosed as having systemic lupus erythematosus (SLE), only 11 having active SLE had IgG antibody levels of greater than 5.0 microgram/ml to single-strand DNA. Renal involvement of some degree was found in all 11 with the high concentrations of IgG antibodies to DNA correlating with severe involvement. Patients with IgM antibodies to DNA alone had more benign types of SLE with little renal involvement. No abnormal levels of IgA Ab to either single-strand DNA or double-strand DNA were found in SLE patients' sera. Corticosteroid and/or immunosuppressant treatment caused a marked drop in the IgM Ab level to DNA within 10 days while IgG Ab to DNA remained high for up to 30 days. Quantitation of IgG and IgM Ab to single-strand DNA provides a useful method for diagnosing severe SLE with possible renal involvement and monitoring the course of the disease during therapy.

Elevated levels of antibodies to polyuridylic acid detected and quantitated in systemic scleroderma patients by solid phase radioimmunoassay.

A solid support radioimmunoassay has been developed to detect immunoglobulin specific circulating antibodies to polyuridylic acid (Pol U), single-stranded RNA (ss RNA), and single-stranded DNA (ss DNA) in scleroderma and other connective tissue diseases. The assay system uses flex-vinyl microtiter plates on which bovine methyl albumin, the respective polynucleotide, a 1:80 dilution of patient serum, and tritiated high affinity anti-IgG, -IgA, or -IgM are layered. The individual wells containing the sandwich assay are then counted for the presence of labeled immunoglobulins and the results are reported in microgram/ml. Of the 30 scleroderma patients tested, only patients with diffuse systemic scleroderma had antibody levels reactive to Poly U > 4.0 microgram/ml and to ss RNA < 3.0 microgram/ml. Patients with linear scleroderma or morphea had antibody levels to Poly U < 3.0 microgram/ml and very little antibody to ss DNA or ss RNA in their sera. Partial cross reactivity to Poly U was found only in SLE patients with high levels of Ab to ss DNA. Insignificant levels of Poly U antibody were found in patients with other connective tissue diseases and in normal controls. High levels of serum antibody in patients which reacted with Poly U suggest active diffuse systemic scleroderma.

Optimising µCT imaging of the middle and inner cat ear.

This study's aim was to determine the optimal scan parameters for imaging the middle and inner ear of the cat with micro-computertomography (µCT). Besides, the study set out to assess whether adequate image quality can be obtained to use µCT in diagnostics and research on cat ears. For optimisation, µCT imaging of two cat skull preparations was performed using 36 different scanning protocols. The µCT-scans were evaluated by four experienced experts with regard to the image quality and detail detectability. By compiling a ranking of the results, the best possible scan parameters could be determined. From a third cat's skull, a µCT-scan, using these optimised scan parameters, and a comparative clinical CT-scan were acquired. Afterwards, histological specimens of the ears were produced which were compared to the µCT-images. The comparison shows that the osseous structures are depicted in detail. Although soft tissues cannot be differentiated, the osseous structures serve as valuable spatial orientation of relevant nerves and muscles. Clinical CT can depict many anatomical structures which can also be seen on µCT-images, but these appear a lot less sharp and also less detailed than with µCT.