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J D Sipe

Publications and source records attributed to J D Sipe.

At least 55 records · Page 3Linked to original sources
PubMed1994

Combined treatment with terbutaline and aminophylline inhibits experimental amyloidosis in mice.

OBJECTIVE: To investigate the effects of drugs known to elevate adenosine 3':5'-cyclic monophosphate (cAMP) on experimental amyloidosis. METHODS: A beta 2-agonist, terbutaline, and a phosphodiesterase inhibitor, aminophylline, were administered in combination in a mouse model of amyloidosis induced by inflammatory stimulation with silver nitrate. Amyloidosis was quantitated by radioimmunoassay for splenic amyloid A (AA) protein. RESULTS: At the doses selected, aminophylline/terbutaline inhibited splenic amyloid deposition more potently than did colchicine, a known inhibitor of amyloidosis. CONCLUSION: Drugs known to elevate cAMP inhibit experimental mouse AA amyloidosis.

Adrenergic beta-Agonists↗
PubMed1994

Amyloidosis.

The biochemistry of amyloidosis as it relates to clinical medicine and experimental pathology is presented. Amyloidoses are complex disorders in which normally soluble precursors undergo pathological conformational changes and polymerize as insoluble fibrils with the beta-pleated sheet conformation. Over the past 20 years, 16 biochemically diverse proteins have been identified as fibrillar constituents of amyloid deposits; in all cases the protein-protein interactions that result in amyloid fibril formation appear to be stabilized both by the structure and the microenvironment of the precursor protein. Either genetic predisposition or dysfunctions of the immune system favor amyloid fibril formation. In particular, macrophage function is a factor in the pathogenesis of many of the amyloidoses. The diagnosis of amyloidosis involves acquisition of a tissue biopsy, staining of the specimen with Congo red, and observation of classic green birefringence on polarization microscopy. The subdiagnosis of the systemic amyloidoses involves characterization of variant or monoclonal plasma amyloid precursor proteins in the context of clinical symptoms. Treatment is generally supportive, with the use of antiinflammatory therapy, dialysis, or transplantation and genetic counseling where indicated.

Amyloid↗
PubMed1994

Synergism of interleukin 1 and interleukin 6 induces serum amyloid A production while depressing fibrinogen: a quantitative analysis.

OBJECTIVE: Production of the serum amyloid A (SAA) proteins in the liver of patients with arthritis can be increased from approximately 1 microgram/ml to > 1000 micrograms/ml, while fibrinogen (Fg) can be increased from 2 to 9 mg/ml. The increases appear to be regulated by mediators similar to those found in inflamed joints, e.g., interleukins 1 and 6 (IL-1 and IL-6, respectively). The sensitivity and dose response of SAA and Fg synthesis by hepatoma cells to IL-1 and IL-6 was investigated to understand the relationship between the inflammatory cytokines produced in inflamed joints and the acute phase protein response in the liver of arthritis patients. METHODS: SAA and Fg mRNA and protein production in human Hep3B cells stimulated by human monocyte conditioned medium (CM) containing known amounts of IL-1 and IL-6, or stimulated by corresponding concentrations of recombinant IL-1 and IL-6 was analyzed by ELISA and Northern blot hybridization techniques. RESULTS: Increases in SAA mRNA and protein were dose dependent in the presence of IL-1 and IL-6 at concentrations ranging from 0.1 and 1 ng/ml, respectively, to 10 and 100 ng/ml, respectively. In the presence of IL-1 receptor antagonist (IL-1ra), there was a 75% decrease in SAA production and > 100% increase in Fg production by cells stimulated with CM. CONCLUSION: Our results demonstrate that the thousand fold dynamic range associated with the acute phase SAA response requires IL-1 acting synergistically with cytokine(s) like IL-6. Optimum conditions for apoSAA production are suboptimal for Fg as indicated by the differential effects of IL-1ra.

Carcinoma, Hepatocellular↗
PubMed1993

Syrian and Armenian hamsters differ in serum amyloid A gene expression. Identification of novel Syrian hamster serum amyloid A subtypes.

Amyloid A (AA) amyloidosis is widespread throughout the animal kingdom. Several factors including: 1) precursor production; 2) precursor structure; 3) precursor degradation; and 4) precursor/product interaction with the pentraxin serum amyloid P have been implicated in amyloidogenesis, but the exact sequence of events leading to AA fibril formation and deposition remains unclear. Most models of experimental amyloidosis, including golden Syrian hamsters (Mesocricetus auratus), involve massive and repeated inflammatory stimulation; however, the model of spontaneous amyloidosis with aging in female, but not male, Syrian hamsters permits analysis of amyloidogenic factors in the absence of inflammation. Another genus, the Armenian hamster (Cricetulus migratorius), differs from Syrian hamsters both in gender-specific serum amyloid P expression and susceptibility to AA amyloidosis. In this study, we describe novel SAA molecules in the Syrian hamster in the presence and absence of inflammation. We demonstrate that, based on isoelectric separation, the Syrian hamster SAA proteins can be separated into two broad subfamilies. Plasma SAA concentration in female Syrian hamsters increases spontaneously with age, and fragments of a basic SAA isotype expressed both hepatically and extrahepatically are selectively deposited as AA fibrils. After inflammatory stimulation, the patterns of SAA gene expression in Syrian and Armenian hamsters differ. In Syrian hamsters, both hepatic SAA mRNA and the high density lipoprotein apoSAA content increase approximately 1000-fold; in Armenian hamsters, hepatic SAA mRNA is limited in quantity and different in structure; and although plasma SAA proteins increase three- to fivefold, apoSAA is not detectable in high density lipoprotein. The results suggest that regulation and site of precursor production as well as precursor structure influence AA amyloidogenesis in these two hamster genera.

Amino Acid Sequence↗
PubMed1993

Increased fibrinogen synthesis in mice during the acute phase response: co-operative interaction of interleukin 1, interleukin 6, and interleukin 1 receptor antagonist.

Interleukin 6 (IL-6) stimulates fibrinogen (Fg) gene expression both in vivo and in vitro; while interleukin 1 (IL-1) paradoxically stimulates in vivo, yet inhibits in vitro, Fg synthesis. The naturally occurring interleukin 1 receptor antagonist (IL-1ra) and passive immunization with anti-IL-6 antiserum were used to study the in vivo mechanism of action of IL-1 on Fg gene expression. Changes in plasma Fg and hepatic Fg mRNA concentrations were measured following administration of exogenous IL-1ra together with IL-6 or IL-1 to CD2F1 mice. Our results suggest that in vivo, IL-1 per se inhibits Fg production since when IL-1ra was co-administered with IL-6, greater concentrations of Fg were observed than when IL-6 was administered alone. The data suggest that IL-1 stimulates Fg production through intermediate production of IL-6, since stimulation was abrogated when either IL-1ra or anti-IL-6 antiserum was co-administered with IL-1. An in vivo role for IL-1ra in the stimulation of Fg by IL-1 was supported by the observation that within 1 h of IL-1 administration to mice, IL-1ra mRNA was detectable in liver. It appears that IL-1, an early mediator of inflammation, inhibits constitutive expression of Fg genes and stimulates the IL-1ra and IL-6 genes. The inhibitory effect of IL-1 is reversed by endogenous IL-1ra and by the direct stimulation of Fg gene expression by IL-6.

Acute-Phase Reaction↗
PubMed1993

Reduction of acute-phase proteins with tenidap sodium, a cytokine-modulating anti-rheumatic drug.

Four independent studies have investigated and compared the effects of tenidap sodium, naproxen and placebo on CRP in patients with active RA. One of these studies also investigated the effects of tenidap and naproxen on serum amyloid A (SAA) concentrations and ESR. The duration of the four studies ranged between 2 weeks and 24 weeks, and depending on the study, tenidap sodium was administered orally in doses of 40-120 mg/day and naproxen in doses of 1000 mg/day. In all four studies serum CRP concentrations in tenidap-treated patients had decreased significantly from baseline at the time of final assessment. The decrease in CRP concentration in tenidap-treated patients was observed as early as 1 week after initiation of therapy and was sustained for up to 6 months, the last assessment timepoint. CRP concentrations in naproxen-treated and placebo patients were essentially unchanged. The decreases from baseline observed in tenidap-treated patients were significantly greater than the changes observed in naproxen-treated or placebo patients. After 24 weeks of tenidap treatment the decrease in CRP was paralleled by significant decreases in SAA concentration and ESR. The finding that tenidap sodium rapidly, consistently and significantly lowered CRP serum concentrations differentiates tenidap sodium from the NSAID, naproxen. This could possibly have important therapeutic implications given that other long-term investigations have shown that reducing serum CRP and SAA concentrations correlates with a reduction in radiographically-assessed disease progression.

Acute-Phase Proteins↗
PubMed1993

Characterization of the inbred CE/J mouse strain as amyloid resistant.

Inbred CE/J mice have been identified as extremely resistant to azocasein-induced amyloidosis relative to five commonly used inbred strains, A/J, CBA/J, C57BL/6J, C3H/HeN, and SJL/J. The enhanced amyloid resistance in CE/J mice seems to derive from the novel structure of the SAA gene family in CE/J mice, as determined by Southern blot hybridization analysis of SAA gene structure and isoelectric focusing analysis of acute phase SAA proteins in the six inbred strains. In CE/J mice, a single, novel SAA isoform of pI 6.15 is present, whereas in the other strains the amyloidogenic SAA2 isoform (pI 6.3) is codominantly expressed with SAA1 (pI 6.45). Two other inbred strains, PERU and IS/CAM, share common SAA specific HindIII DNA fragments with CE/J mice. Wild-derived Mus musculus mice differ from all of the inbred strains studied, both in SAA gene structure and in the pattern of SAA isoform production; two isoforms, one pI 6.15 and the other pI 6.3 (corresponding to SAA2), were codominantly expressed. Only the pI 6.15 isoform, not SAA1 and 2, was produced by CE/J mice in response to lipopolysaccharide, casein, silver nitrate, interleukin-1, or tumor necrosis factor; tumor necrosis factor was a weaker stimulus than interleukin-1 for the pI 6.15 isoform as it is for SAA1 and 2 production in the other inbred strains. This study provides a new line of evidence supporting the role of precursor structure as a determining factor in murine amyloid A amyloidosis and provides a valuable model for studies of amyloidogenesis.

Acute-Phase Reaction↗
PubMed1992

Mouse serum amyloid A protein. Complete amino acid sequence and mRNA analysis of a new isoform.

Four serum amyloid A protein (SAA) genes and two gene products, apo-SAA1 and apo-SAA2 were identified in BALB/c mice (type A). SJL/J mice (type B) are thought to be defective in apo-SAA2 expression. A unique variant of mouse apo-SAA was identified in SJL/J mice by isoelectric-focusing analysis of high-density lipoprotein from endotoxin-treated mice. Complete amino-acid-sequence analysis of this quantitatively major form of SJL/J apo-SAA (pI 5.9) showed it to be identical with the apo-SAA2 isoform from BALB/c mice, except for the substitution of aspartic acid for alanine at position 101. Isoform-specific analysis of mRNA from liver of BALB/c and SJL/J mice and their F1 hybrid progeny (CSJLF1/J) mice revealed further differences in the 3' untranslated regions of the genes, not only encoding apo-SAA2 and apo-SAA pI 5.9, but also apo-SAA1. The SAA genes of SJL/J mice thus differ from BALB/c in exon 4. Additional minor isoforms corresponding to apo-SAA2 (pI 6.3) in SJL/J mice and apo-SAA (pI 5.9) in BALB/c mice were identified. We propose that, when analysing a multigene family such as SAA, thorough analysis at the protein level should complement molecular-biological approaches where the use of a too-limited repertoire of probes can obscure complexities.

Amino Acid Sequence↗
PubMed1992

Human serum amyloid A protein. Complete amino acid sequence of a new variant.

Serum amyloid A protein (SAA), an acute-phase reactant and apolipoprotein of high-density lipoprotein, is a polymorphic protein with six reported isoforms. These are the products of three genes, i.e., cDNA pA1, cDNA pSAA82 and genomic DNA SAAg9, the last two being allelic variants at a single locus. We have identified an individual with additional novel SAA isoforms on isoelectric-focusing analysis. By using 3-bromo-3-methyl-2-(2'-nitrophenylsulphenyl)-indolenine (BNPS-skatole) cleavage of the protein at tryptophan residues we obtained the complete amino acid sequence of a novel isoform. Additional cleavage by endoproteinase Asp-N allowed verification of the tryptophan residues and complete amino acid sequence of both isoforms. The suitability of this approach to the rapid sequencing of SAA was demonstrated. Sequence analysis and quantification suggest that these isoforms are the result of the first confirmed allelic variation at the SAA1 locus. We designate the protein products of this allele SAA1 beta (pI 6.1) and SAA1 beta des-Arg (pI 5.6).

Amino Acid Sequence↗
PubMed1992

Modification of proinflammatory cytokine production by the antirheumatic agents tenidap and naproxen. A possible correlate with clinical acute phase response.

The cytokines IL-6, IL-1, and TNF play a key role in the pathogenesis of rheumatoid arthritis (RA) and initiate hepatic serum amyloid A (SAA) expression after injury. To provide a possible mechanistic explanation for the previous observation that plasma SAA concentrations decreased during treatment of RA patients with tenidap, but increased during treatment with naproxen, the present study compared the effects of tenidap and naproxen on the two stages of SAA expression: cytokine production by human PBMC and cytokine-stimulated SAA synthesis by human Hep3B hepatoma cells. Tenidap inhibited production of IL-6 greater than TNF greater than IL-1; the effect of naproxen on production of all three cytokines was lesser and least on IL-6. Indeed, an increase in IL-6 production was observed after exposure to naproxen. PBMC beta-2-microglobulin production and total protein synthesis were unaffected at concentrations and times at which effects on cytokine production were observed. Cell density was a significant factor in the extent to which cytokines were stimulated by LPS. Approximately physiologic cell densities, 0.5 to 1 x 10(6) cells/ml, were optimal for stimulation of IL-1-beta and IL-6 production by LPS; however, greater amounts of TNF were produced at lower cell densities. Because neither tenidap nor naproxen inhibited SAA synthesis by cytokine-stimulated Hep3B cells and because they differ most significantly in their effect on IL-6 production, the results support a role for IL-6 in the continued stimulation of SAA production during RA.

Acute-Phase Reaction↗
PubMed1992

Suppression of IL-2-induced SAA gene expression in mice by the administration of an IL-1 receptor antagonist.

The hepatic acute phase response induced by the administration of interleukin (IL)-2 is most likely mediated by secondary cytokines. In this investigation, we examined the role of endogenous IL-1 in the synthesis of the hepatic acute phase protein serum amyloid A (SAA) during IL-2 treatment. The injection of IL-2 induced SAA gene expression in the liver. The concurrent administration of an IL-1 receptor antagonist (IL-1RA) markedly reduced hepatic SAA mRNA levels and, to a lesser extent, SAA protein levels in the serum. Although IL-1 is an inducer of IL-6 production, the administration of the IL-1RA had no effect on circulating IL-6 levels in IL-2-treated mice. These findings suggest that the production of IL-1 is an important factor in the induction of SAA mRNA in mice undergoing immunotherapy with IL-2.

Animals↗
PubMed1992

Amyloidosis.

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Amyloid↗
PubMed1991

Major acute-phase reactant synthesis during chronic inflammation in amyloid-susceptible and -resistant mouse strains.

Hepatic levels of mRNA specific for total serum amyloid A (SAA), the SAA1 and SAA2 isotypes, serum amyloid P (SAP), C-reactive protein (CRP), and fibronectin, as well as the plasma concentrations of SAA and SAP were examined in amyloid-resistant (A/J) and amyloid-susceptible (CBA/J) mice during azocasein-induced chronic inflammation. In both strains hepatic SAA and SAP mRNA levels and plasma SAA and SAP protein concentrations increased dramatically during the early stages of inflammation; this was followed by a decrease to concentrations that were maintained at levels considerably higher than background. The ratios of SAA1 and SAA2 mRNA and plasma protein were 1:1 throughout. This indicated that there was no preferential accumulation of mRNA specifying a particular isotype and no preferential synthesis or clearance of a particular isotype during chronic inflammation and the early stages of amyloidogenesis in either strain. Similarly, hepatic SAP mRNA levels in both strains increased dramatically during the early stages of inflammation and were subsequently maintained at elevated levels. Plasma SAP concentrations increased rapidly during the first three days of the study in both A/J and CBA/J mice; however, during the later stages of inflammation, A/J plasma SAP levels decreased to a steady-state concentration that was approximately half that observed in CBA/J mice. Our results identify differences in the hepatic mRNA and plasma protein levels of the major mouse acute-phase reactants (APR) in the amyloid-resistant A/J and amyloid-susceptible CBA/J mouse strains. These findings are consistent with circulating inflammatory APR concentrations contributing, together with other factors, to the onset and pathogenesis of secondary amyloidosis.

Acute-Phase Proteins↗
PubMed1991

Chlorpromazine protection against interleukin-1 and tumor necrosis factor-mediated activities in vivo.

Interleukin (IL-1) and tumor necrosis factor (TNF) are thought to play a key role in septic shock and inflammation. We had previously shown that chlorpromazine (CPZ) has a protective effect in various models of endotoxic shock and IL-1 toxicity. We have tested the effect of CPZ on several activities of IL-1 in vivo. CPZ (4 mg/kg) inhibited increases in serum corticosterone, triglycerides and serum amyloid A (SAA). Chlorpromazine also antagonized these same effects when they were induced by endotoxin or TNF, suggesting that this activity could be implicated in the protective effect of CPZ in various models of endotoxic shock and IL-1 lethality.

Animals↗
PubMed1989

Direct binding enzyme-linked immunosorbent assay (ELISA) for serum amyloid A (SAA).

A solid-phase, direct binding ELISA for serum amyloid A (SAA) proteins is described, in which noncovalent interactions of SAA with other plasma constituents are disrupted to permit direct coating of the wells of flexible polyvinyl chloride microtitration plates with an amount of SAA antigen proportional to its concentration in plasma. The wells are coated overnight at 60 degrees C with plasma diluted in 3 M potassium bromide and 0.1 M sodium bicarbonate. pH 9.6. The next day, any remaining sites on the wells are blocked by incubation for 1 h at ambient temperature with a 5% solution of dry milk solids and 0.05% Tween 20 in 0.02 M phosphate buffer, pH 7.4. The wells are rinsed and incubated for 90 min at 37 degrees C with polyclonal rabbit or rat anti-human SAA antiserum. Then, the wells are rinsed and incubated with goat anti-rabbit or rat IgG antiserum to which has been conjugated horseradish peroxidase. o-phenylenediamine and hydrogen peroxide substrates are added to the wells, color is allowed to develop, and sulfuric acid is added to stop the enzyme-catalyzed reaction. The amount of SAA coated to wells is quantified by absorbance at 490 nm. Four or more serial three-fold dilutions of plasma samples are assayed simultaneously on separate plates. Each plate contains a set of wells with identical concentrations of SAA standard protein diluted in decreasing concentrations of plasma proteins corresponding to the dilution of sample. The method can detect SAA concentrations in plasma samples ranging from 1 microgram/ml to greater than 1000 micrograms/ml. The method is suited to serial monitoring of SAA concentration in patients undergoing treatment for inflammatory conditions and to the quantitative analysis of large numbers of samples.

Blotting, Western↗