Search PubMed⌕ Search

Biomedical subjects

J D Sipe

Publications and source records attributed to J D Sipe.

At least 109 records · Page 6Linked to original sources
PubMed1979

Detection of a mediator derived from endotoxin-stimulated macrohpages that induces the acute phase serum amyloid A response in mice.

The mechanism by which LPS stimulates an acute phase serum amyloid A (SAA) response in C3H mice has been studied. A factor (SAA inducer) appears in the blood of C3H/HeN (lipopolysaccharide [LPS]-sensitive) mice approximately 1 h after administration of LPS, which, when passively administered, can induce C3H/HeJ mice to produce SAA although they are resistant to the LPS itself. SAA inducer has been detected in the culture medium of LPS treated C3H/HeN macrophages but not spleen cells. Thus, two stages in the induction of the acute phase SAA response are now recognized: a latent period of 2-3 h during which the SAA concentration remains at baseline values and in which SAA inducer appears, and the period of synthesis of SAA which lasts for approoximately 24 h past induction. It is proposed that a macrophage response to LPS is responsible for production of the serum mediator which induces SAA synthesis.

Amyloid↗
PubMed1979

Levels of the serum amyloid A protein (SAA) in normal persons of different age groups.

Serum amyloid A (SAA) has been implicated by three independent studies to increase in concentration with ageing. The present study measured SAA concentration in 395 samples from 302 healthy individuals ranging in age from 21 to 100 years. The average SAA concentration was 20 microgram/ml, with only five serum samples falling below 5 microgram/ml. SAA concentrations are expressed in terms of cross-reactivity of purified, denatured SAA with anti-AA antibodies, rather than the purified, denatured amyloid fibril protein AA from tissues, which has been used in the past. No age-related increase in SAA concentration was observed in the present study. The average SAA concentration in these normal, healthy individuals was almost a hundred-fold less than values measured in acute phase human serum in a separate study with the same reagents.

Adult↗
PubMed1978

Changes in human serum amyloid A and C-reactive protein after etiocholanolone-induced inflammation.

Secondary amyloidosis is a complication of diseases characterized by recurrent acute inflammation. In this study, a standardized stimulus which induced fever and inflammation was given to six normal subjects (19-24 yr old) to follow the fluctuation in concentration of serum amyloid A (SAA), the precursor of the secondary amyloid fibril protein. After a single intramuscular injection of etiocholanolone (0.3 mg/kg), blood samples were drawn twice a day for 12 days for determination of SAA by solid phase radioimmunoassay. From a base line of <100 mug/ml, the SAA concentration began rising within 12 h to a maximum value at about 48 h of 1,350-1,800 mug/ml in three males and 380-900 mug/ml in three females and returned to base line by 4-5 days. The SAA response showed a similar time response to C-reactive protein (CRP), a well-documented acute phase protein which was assayed semiquantitatively by capillary tube precipitin reaction. CRP, but not SAA, showed a quantitative correlation with the amount of fever induced by etiocholanolone. One subject exhibited a second rise in SAA and CRP concentrations after acute over-indulgence with alcohol, suggesting that acute liver damage may have caused an acute phase reaction. Thus, a controlled episode of fever and inflammation produced a prompt and prolonged elevation of SAA and CRP concentrations. Unlike SAA, CRP has not been implicated in the pathogenesis of amyloidosis, although its relationship to the P component of amyloid has recently been established.

Amyloid↗
PubMed1978

Induction of the acute-phase serum protein SAA requires both RNA and protein synthesis.

SAA is a normal acute-phase serum protein which has been identified by its cross-reaction with antibodies to the amyloid A fibril protein, AA, that is associated with secondary amyloidosis. The induction of SAA by bacterial lipopolysaccharide (LPS) has been studied with 3 inhibitors of protein synthesis: cycloheximide, actinomycin D, and galactosamine. Each of the 3 agents when administered simultaneously with LPS completely abolishes induction of SAA for at least 6 h. They are all significantly effective when given 1.5 h after LPS but 3 h after LPS the inhibitory effect of actinomycin D on SAA induction is markedly reduced. Cycloheximide alone can also induce significant concentration of SAA, but a longer time is required than for LPS. Thus it appears that the acute-phase SAA response is characterized by both RNA and protein synthesis which is initiated by the acute-phase inducing agent and which precedes the appearance of elevated SAA concentrations in the serum.

Amyloid↗
PubMed1977

Isolation and structural properties of murine SAA--the acute phase serum precursor of amyloid AA.

The murine serum protein SAA, has been found to have a structure similar to human SAA, the precursor of human secondary amyloid fibril protein AA. SAA is detected by its cross-reaction in radioimmunoassay with antibodies raised to denatured amyloid fibrils of protein AA isolated from tissues of mice with amyloidosis. Murine SAA exists in the native state as a 160,000 molecular weight species, and can be isolated as a 12,500 molecular weight moiety, SAAL, by gel filtration in 10% formic acid. The quaternary structure of SAA is such that its AA determinants are relatively inaccessible for immunoreaction. Unfolding of these determinants can occur spontaneously; however, it is promoted by dissociation of SAA to SAAL.

Amyloid↗
PubMed1977

Immunochemical studies on the nature of the serum component (SAA) related to secondary amyloidosis.

The relative occurrence of the amyloid-related serum protein SAA in various disease states and in healthy subjects has been compared by both solid phase radioimmunoassay ((RIA) and immunodiffusion techniques which employ antibodies to purified amyloid fibril proten AA of hemogeneous size and charge. SAA levels were elevated above normal in certain categories of neoplastic, inflammatory, and infectious diseases as well as in secondary amyloidosis. The lowest median value, 8 ng./ml., was observed for approximately 150 normal sera, with no age-related increase in subjects ranging in age from 16 to 70 years. The results are consistent with several recent observations that SAA is normal acute phase reactant, and hence the RIA for SAA has no prognostic or diagnostic significance for secondary amyloidosis. The sensitivity of RIA for the detection of SAA is lower than would be expected when AA cross-reactivity values for sera are correlated with their reaction with anti-AA antibodies in immunodiffusion. This observation, along with others reported elsewhere suggests that those determinants which cross-react with anti-AA antibodies are relatively hidden in native SAA. Myeloma sera were less reactive than other groups of pathologic sera in immunodiffusion, although they were similar to other patients' sera when analyzed by RIA. Antibodies to highly purified AA were also used to investigate the structue of SAA by a double-antibody immunoprecipitation method. Precipitated SAA was partially dissociated during sodium dodecyl sulfate-urea-polyacrylamide gel electrophoresis to a 12,500 molecular weight moiety designated, SAAL. Multiple radiolabeled species of molecular weight intermidiate to SAA and SAAL were also detected and appeared to represent imcompletely dissociated SAA. The results suggest the SAA is an aggregate of several SAAL chains.

Adolescent↗
PubMed1976

Murine model for human secondary amyloidosis: genetic variability of the acute-phase serum protein SAA response to endotoxins and casein.

The serum precursor SAA of the secondary amyloid protein AA has been detected by solid-phase radioimmunoassay as a normal serum alpha-globulin of mol wt 160,000, which dissociates to a more stable 12,500 dalton moiety on treatment with formic acid. In 12 strains of mice, including T-cell-deficient nude mice, treated with the amyloid-inducing agents lipopolysaccharide (LPS) or casein, SAA behaved as an acute-phase reactant. SAA concentration rose to about 750 mug/ml by 24 h and returned to less than 1 mug/ml by 48 h. Since the amyloid-resistant colchicine-treated mice and AJ mice had a normal SAA response to LPS, it appears that their resistance to amyloid induction is due to the nature of their SAA processing rather than decreased SAA production. C3H/HeJ mice, which have defective B-lymphocyte responses to LPS, required extremely high dosages of LPS to cause SAA elevation, although their SAA response to casein was normal. This suggests that SAA is an acute-phase protein produced as a result of B-lymphocyte stimulation. Preliminary evidence suggests that at the height of an acute SAA response, liver homogenates are particularly rich in protein AA cross-reacting material.

Acute Disease↗
PubMed1976

Amyloid fibril protein AA: purification and properties of the antigenically related serum component as determined by solid phase radioimmunoassay.

The isolation by gel filtration of a serum component (SAA), antigenically related to the major filbrillar amyloid protein (AA), associated with "secondary" amyloidosis, has been monitored by a solid phase radioimmunoassay for the AA protein to detect cross-reacting serum fractions. Evidence is presented that not all cross-reacting antigenic determinants are accessible in native SAA, since additional determinants are revealed during the isolation procedure. The native structure of SAA appears to be quite labile. SAA from freshly collected serum has a m.w. of 180,000 and co-chromatographs with IgG. However, species of higher m.w. are observed after storage of serum at 4 degrees C or upon chromatography of serum in ammonium bicarbonate. Denatured SAA has a tendency to aggregate under strong dissociating conditions. A 12.500 m.w. antigenic species (SAAL) was detected upon guanidine-HCl denaturation of SAA, by earlier studies employing double immunodiffusion. However, evidence is presented here that the major part of the antigenic acitivity after guanidine-HCl treatment was of m.w. greater than 12,500, but was unreactive in double immunodiffusion. Formic acid treatment of cross-reacting serum fractions does result in virtually complete dissociation of SAA to SAAL, however. Furthermore, Formic acid-dissociated SAAL is of comparable immunoreactivity with AA, on a molar basis, unlike SAAL obtained from SAA by guanidine-HCl denaturation.

Amyloid↗
PubMed1976

Conformational flexibility of the serum amyloid precursor SAA.

SAA is a normal acute-phase serum protein and is thought to be the precursor of amyloid protein AA which is deposited as insoluble beta-pleated sheet fibrils in secondary amyloidosis. Native SAA has a molecular weight of 160,000 and has not been isolated; it has been most frequently purified as a species (designated SAAL) of 12,500 mol. wt. by gel filtration in dissociating solutions. The conformational properties of SAA proteins in patients with and without amyloidosis have been compared in an effort to determine the factors involved in the induction of the beta-pleated sheet conformation in the amyloid SAA protein prior to fibril deposition. Amyloid and nonamyloid SAA proteins are similar in that they readily undergo conformational changes which result in the formation of heterogenous mol. wt. SAA species and in an increased exposure of antigenic determinants which cross-react with AA fibril proteins. Amyloid and nonamyloid SAA are different, however, in that amyloid SAA is more resistant to dissociation to SAAL. Amyloid SAAL, while similar to nonamyloid SAAL in immunoreactivity, shows a greater tendency toward aggregation. The relative resistance of both amyloid SAA and SAAL to complete dissociation may play an important role in amyloid fibril formation from these precursors.

Amyloid↗
PubMed1975

Isolation of a low-molecular-weight serum component antigenically related to an amyloid fibril protein of unknown origin.

An amyloid fibril protein of unknown origin from a patient with systemic amyloidosis has been purified to homogeneous charge and size by gel filtration and two step isoelectric focusing. From crude antisera to the initial heterogeneous fibril protein, monospecific antibodies have been obtained by immunoabsorption with the immobilized purified amyloid protein. These antibodies have been used to identify an antigenically related serum component in whole sera of patients with and without amyloidosis. Chromatography on Sephadex G-200 in phosphate buffered saline of a patient's whole serum yields a component with an apparent molecular weight of approximately 200,000. Guanidine denaturation of this high-molecular-weight serum component followed by Sephadex G-100 column chromatography in 5 M guanidine affords an antigenically reactive protein with an apparent molecular weight of about 12,500. The antigenic similarity and molecular weight of the latter protein indicates that it could act as the smallest serum precursor of the tissue fibril protein in this group of cases of amyloidosis.

Amyloid↗
PubMed1973

Purification of mouse interferon by affinity chromatography on a solid-phase immunoadsorbent.

A solid-phase immunoadsorbent capable of binding mouse interferon has been prepared. Starting from crude tissue-culture material, interferon could be purified 1990 times in a single step of affinity chromatography. Overall recovery ranged from 55 to 103% with tissue culture and mouse-brain interferon; however, only 5% was obtained with Sendai virus-induced interferon from mouse serum.

Animals↗
PubMed1973

Preparation of solid-phase immunosorbents by coupling human serum proteins to cyanogen bromide-activated agarose.

The method of preparing solid-phase immunosorbents by covalently attaching proteins from whole human serum to cyanogen bromide-activated agarose has been investigated to determine optimum concentrations of cyanogen bromide and protein, and the optimum pH for the maximum attachment of proteins from serum. Two systems in which the above immunosorbents have proved useful are described: the removal of antibodies to normal serum proteins from anti-hepatitis B serum and the removal of light chain antibodies from anti-human immunoglobulin M serum.

Absorption↗
PubMed1968

Separation of ten reovirus genome segments by polyacrylamide gel electrophoresis.

Double-stranded ribonucleic acid (RNA) extracted from purified reoviruses of all three serotypes and from type 3 virus-infected cells was analyzed by polyacrylamide gel electrophoresis. It was calculated that each RNA includes 10 segments: 3 large, 3 intermediate, and 4 small fragments corresponding to molecular weights of about 2.5, 1.4, and 0.8 x 10(6) daltons, respectively, or a total of 15 x 10(6) daltons.

Acrylates↗
PubMedDate not supplied

Synthesis and secretion of active alpha 1-antichymotrypsin by murine primary astrocytes.

Activated astrocytes have been identified as the main source of the serine protease inhibitor alpha 1-antichymotrypsin (ACT), an acute phase protein that is tightly associated with amyloid plaques in Alzheimer's disease (AD) and in normal aged human and monkey brain. We analyzed the synthesis of ACT by cultured murine astrocytes in vitro. The murine astrocytes expressed an ACT-like antigen that crossreacted with antibodies to human ACT. The murine ACT-like protein is secreted by the astrocytes and is able to form an SDS-resistant complex with the serine protease cathepsin G, indicating that the secreted ACT is biologically active. We conclude that cultured primary astrocytes synthesize and secrete murine ACT in an active form. We, therefore, suggest that the ACT present within AD plaques is locally derived from plaque-associated activated astrocytes as a part of a glia-mediated local inflammatory response that is associated with the neurodegeneration seen in AD.

Animals↗