Search PubMed⌕ Search

Biomedical subjects

C R Steinman

Publications and source records attributed to C R Steinman.

36 records · Page 2Linked to original sources
PubMed1977

Binding of synthetic double-stranded DNA by serum from patients with systemic lupus erythematosus: correlation with renal histology.

Detection of antibody to double-stranded DNA by direct binding assays has proved useful in clinical management of patients with systemic lupus erythematosus (SLE). Recent confusion regarding specificity of these antibodies for SLE appears to be due, at least in part, to contamination of natural DNA preparations with nondouble-stranded DNA antigens. Measurement of binding of a synthetic, self-complementary DNA copolymer (dAT) rather than of natural DNA (KB) has been shown to obviate some of these difficulties, apparently because of freedom of dAT from nondouble-stranded DNA antigens. Among the advantages found in this way was a higher degree of specificity of antibodies to double-stranded DNA for clinically-judged active lupus nephritis than had been suspected. Since activity of nephritis is difficult to assess clinically, histologic data were sought to confirm these observations. Thirty-two kidney specimens were examined by light and/or electron microscopy. The degree of histologic activity and the amount and location of glomerular electron-dense deposits were semiquantitated blindly. The binding of both dAT and KB DNA was measured by the ammonium sulfate method. Correlation with the amount of electron-defense deposits was highly significant for dAT binding and somewhat less so for KB DNA binding as determined by both parametric and nonparametric statistical methods. Significant correlation with histologic activity was found for dAT but not KB DNA binding. These results are consistent with previous data and suggest that dAT binding may provide a useful, noninvasive means of clinically assessing both nephritis activity and the intensity of glomerular immune-complex deposition as reflected by the amount of electron-dense deposits. If it can be confirmed that the latter provides long-term prognostic information, then dAT binding (and perhaps its reponse to therapy) may also prove of value in this regard.

Adenosine Monophosphate↗
PubMed1977

Appearance of circulating DNA during hemodialysis.

The appearance of circulating DNA during hemodialysis was investigated by use of a modified counterimmunoelectrophoresis assay capable of detecting as little as 0.02 to 0.05 microng of native DNA per milliliter of plasma. It was found that free DNA was regularly released during procedure in widely varying amounts which ranged as high as 5 microng/ml. Both the amount of plasma DNA and its rate of appearance increased progressively throughout the procedure and had no temporal correlation with the transitory early leukopenia that was previously described. Circulation in vitro of fresh blood through a dialysis coil also resulted in the appearance of plasma DNA suggesting that passage of blood through the coil itself can account, at least in part, for circulating DNA, presumably by release from leukocytes. Neither the presence (nor reversal) of the uremic state per se nor removal of inhibitors of the assay during hemodialysis are able to account for the findings. Whether free circulating DNA is of clinical importance is, as yet, unknown. A hypothesis is proposed linking chronic exposure to circulating intracellular materials, including DNA, to the accelerated atherosclerosis recently described as a late complication of hemodialysis. Currently, hemodialysis is the only clinical state known to be characterized by the presence of circulating DNA over long periods of time. Since this phenomenon is iatrogenically induced, further exploration of possible pathogenetic implications seems particularly important.

Adult↗
PubMed1976

Detection of anti-DNA antibody using synthetic antigens. Characterization and clinical significance of binding of poly (deoxyadenylate-deoxythymidylate) by serum.

Virtually all preparations of DNA used to detect antibody to native DNA (nDNA) by binding assays have been found to be subtly contaminated by single stranded DNA. Because recent DNA binding data have directly challenged the unique role previously attributed to these antibodies in systemic lupus erythematosus (SLE), resolution of the consequent ambiguity is of theoretical and practical importance. It is proposed that a synthetic nDNA molecule (dAT) might circumvent this difficulty by being antigenically equivalent to nDNA while, on theoretical grounds, lacking significant contamination with single stranded DNA or other cellular antigens. These expectations were generally confirmed by biochemical and immunological analyses. In clinical studies, sera from 124 pateints with SLE and from controls were examined for their ability to bind dAT. In contrast to results with KB binding, patients with non-SLE rheumatologic disorders were indistinguishable from normals by dAT binding. dAT binding was elevated in 85% of sera from SLE patients with clinically-judged active nephritis but in only 9% of those with inactive renal disease. Active non-renal disease, including cerebritis, was not associated with increased dAT binding. Individual non-lupus sera which bound increased amounts of KB DNA, failed to bind dAT. It is suggested that such binding resulted from contaminating non-nDNA antigens. When elevated, dAT binding, like KB binding, varied with disease activity and might thus be useful as a parameter thereof. In several patients elevated dAT binding led to the finding, on biopsy, of clinically silent, active, diffuse proliferative nephritis. It is concluded that use of synthetic nDNA antigens such as dAT may offer theoretical and practical advantages over naturally-derived preparations in detecting anti-nDNA, both clinically and for investigational purposes. Also, caution is urged in interpreting DNA binding data derived from incompletely characterized systems, particularly with regard to the occurrence of anti-nDNA antibodies in serum.

Adult↗
PubMed1975

Free DNA in serum and plasma from normal adults.

Circulating DNA has been associated with several human disorders, including the nephritis of systemic lupus erythematosus (SLE), in which it is thought to play an etiological role. However, it remains unclear whether its appearance in the circulation is truly pathological. Several reports, each generally based on a single assay method, have disagreed as to whether DNA may circulate in normals. Some, but not all, of this disagreement may be explained by the recently described appearance of DNA in serum, but not plasma, apparently as the result of release from leukocytes in vitro. In the present report an attempt is made to clarify this problem. Normal plasma and serum samples were examined by four assays for DNA that were newly modified to enhance their specificity and/or sensitivity. Plasma DNA was undetectable by all four methods, the most sensitive of which could detect 0.05 mug/ml of native DNA (nDNA) or 0.1 mug/ml of single-stranded DNA (ssDNA). Serum DNA was present in 14 of 16 samples tested in variable concentrations with an estimated mean of 1.9 mug/ml. It is concluded that the appearance of DNA in adult human plasma is a pathological event. Presumably, previous reports describing detection of DNA in normal plasma were based on the measurement of non-DNAase-sensitive interfering substance. Furthermore, it is emphasized that the use of serum in studies dependent on sensitive assays for DNA (or anti-DNA antibody) introduces an ambiguity that may be avoided by substitution of carefully collected plasma for serum.

Adult↗
PubMed1975

Use of nucleic acid hybridization for specific detection of submicrogram quantities of DNA, and its application to human plasma.

A technique is described for using radiolabeled RNA complementary to human DNA as a probe for the specific identification of submicrogram concentrations of human DNA by formation of RNA-DNA hybrids. An example is given of its application to the semiquantitation of human DNA in human plasma, a substance that is ordinarily difficult to examine because materials are present that interfere with the usual colorimetric or fluorometric assays. An example is also given of the use of an analogous approach to analyzing rabbit serum for circulating bacterial DNA. Unique to the hybridization technique is a degree of specificity sufficient to identify specific base sequences and hence the origin of the DNA being detected, a point that may be important in the examination of circulating DNA reported to occur in patients with systemic lupus erythematosis. This technique may also be of value in clarifying the presently conflicting data regarding the occurrence of free DNA in the normal human circulation.

Animals↗
PubMed1975

Specific detection and semiquantitation of micro-organisms in tissue by nucleic acidhybridization. I. Characterization of the method and application to model systems.

On the basis of circumstantial evidence, a number of human diseases have been postulated to result from the presence of occult infection. To investigate this problem amethod of specifically detecting and semiquantitaing trace quantities of bacterial DNA in infected tissue has been devised. It is based on RNA-DNA hybridization using radiolabeled RNAcomplementary to the DNA of the organism being sought. The characteristics of the reaction are shown to conform to those expected for RNA-DNA hybridization and the sensitivity of the method is shown to correspond to approximately one organism per 50 mammalian cells. Specificity at this level of sensitivity is sufficient to clearly distinguish between infections with Listeria monocytogenes and Erysipelothrix insidiosa. This approach may have general applicability forthe study of diseases putatively caused by chronic infection not readily demonstrable bythe usual cultural or immunologic techniques. It may also be useful for helping distinguish contaminants from pathogens when isolates are obtained from diseases tissue. Unique to this approach is the value of negative information in excluding the presenceof an organism within its limits of sensitivity.

Animals↗
PubMedDate not supplied

Specific detection and semiquantitation of microorganisms in tissue by nucleic acid hybridization. II. Investigation of synovia from pigs with chronic Erysipelothrix arthritis.

Synovial tissues from animals with chronic Erysipelothrix arthritis were examined by a technique based on RNA-DNA hybridization in an attempt to detect the inducing organism, Erysipelothrix insidiosa (EI). Twelve synovial specimens from 5 animals whose joints lacked culturable EI also lacked EI detectable by this technique. Because the technique is capable of detecting approximately one organism per 50 mammalian cells, it is concluded that no more than this number were present in the involved tissue. Implications of these results for proposed pathogenetic mechanisms in this disorder and in human rheumatoid arthritis are discussed.

Animals↗