Human serum amyloid A (SAA): biosynthesis and postsynthetic processing of preSAA and structural variants defined by complementary DNA

To study structural variants of human serum amyloid A (SAA), an apoprotein of high-density lipoprotein, complementary DNA clones were isolated from a human liver library with the use of two synthetic oligonucleotide mixtures containing sequences that could code for residues 33-38 and 90-95 of the protein sequence. The SAA-specific cDNA clone (pA1) contains the nucleotide sequence coding for the mature SAA and 10 amino acids of the 18-residue signal peptide. It also includes a 70 nucleotide long 3'-untranslated region and approximately 120 bases of the poly(A) tail. The derived amino acid sequence of pA1 is identical with the alpha form of apoSAA1. A fragment of pA1 containing the conserved (residues 33-38) region of SAA also hybridized with RNA from human acute phase liver and acute phase stimulated, but not unstimulated, mouse and rabbit liver. In contrast, a fragment corresponding to the variable region hybridized to a much greater extent with human than with rabbit or murine RNA. Human acute phase liver SAA mRNA (approximately 600 nucleotides in length) directs synthesis of preSAA (Mr 14 000) in a cell-free translating system. In a Xenopus oocyte translation system preSAA is synthesized and processed to the mature Mr 12 000 product. The complete 18 amino acid signal peptide sequence of preSAA was derived from sequencing cDNA synthesized by "primer extension" from the region of SAA mRNA corresponding to the amino terminus of the mature product. Two other SAA-specific cDNA clones (pA6 and pA10) differed from pA1 in that they lack the internal PstI restriction enzyme site spanning residues 54-56 of pA1.(ABSTRACT TRUNCATED AT 250 WORDS)

Prostaglandin E1 inhibition of experimental amyloidosis in CBA/J mice

The antiinflammatory activity of systemically administered prostaglandin E1 (PGE1) was studied in experimental CBA/J mouse amyloidosis induced by chronic stimulation with silver nitrate. PGE1 lowered splenic deposition of amyloid A protein (AA) (p = 0.035). Serum amyloid A protein (SAA) levels were not suppressed by PGE1 in the acute phase, while decreased SAA levels appeared to be an integral part of the chronic inflammatory phase, with or without PGE1 treatment. Accelerated amyloid deposition induced by amyloid-enhancing factor (AEF) was not blocked by PGE1. This suggests that PGE1 inhibits amyloidosis in the predeposition phase, possibly by preventing formation of AEF or other deposition factors.

Effect of colchicine on experimental amyloidosis in two CBA/J mouse models. Chronic inflammatory stimulation and administration of amyloid-enhancing factor during acute inflammation

To investigate the mechanism of action of colchicine in blocking amyloid deposition, two model systems of amyloidosis in CBA/J mice were studied. In experimental chronic inflammation, daily injection of silver nitrate (AgNO3) resulted in the deposition of 667 +/- 68 ng of amyloid A protein (AA)/mg of spleen after 25 days. Treatment with 10 micrograms of colchicine daily decreased AgNO3-induced AA deposition to 12 +/- 1 ng of AA/mg of spleen (p less than 0.001). Colchicine diminished the acute phase serum amyloid A protein (SAA) response after 24 hours. Over a 25-day period, SAA concentrations declined and approached baseline both in colchicine-treated and (unexpectedly) in control mice. This suggested that suppression of SAA levels was not the primary event inhibiting amyloid deposition. In a model of accelerated amyloid deposition, injection of preformed amyloid-enhancing factor along with AgNO3 induced the deposition of 974 +/- 46 ng of AA/mg of spleen 48 hours later. Colchicine only partially decreased amyloid-enhancing factor-induced amyloid deposition to 578 +/- 91 ng of AA/mg of spleen, while blunting the acute phase SAA response. These results suggest that colchicine inhibits amyloidosis in the predeposition phase, possibly by blocking formation of amyloid-enhancing factor.

Lowered prealbumin levels in patients with familial amyloid polyneuropathy (FAP) and their non-affected but at risk relatives

Amyloid fibrils in familial amyloid polyneuropathy, the familial (AF) form of systemic amyloidosis, are composed of the monomeric unit (14,000 MW) of prealbumin molecules. By radioimmunoassay, the serum level of prealbumin was measured in 25 patients from 12 different kinships with this dominantly inherited form of amyloidosis and 56 unaffected, but at risk, relatives from two of the kinships. Results were compared to prealbumin levels in normal individuals and patients with primary (AL) and secondary (AA) forms of systemic amyloidosis. Significantly lowered prealbumin levels were found in the AF patients (149.2 micrograms/ml) and their at risk relatives (169.0 micrograms/ml) when compared to normal individuals (232.9 micrograms/ml), AL patients (221.9 micrograms/ml) and AA patients (211.7 micrograms/ml). No abnormality was found in levels of retinol binding protein (RBP), which is carried by prealbumin, in the serum of either the AF patients or their relatives. The depressed prealbumin levels may indicate a structural variant molecular form, an extra hepatic synthesis or an abnormality in catabolism of this protein that is present prior to the clinical or histopathologic onset of the AF disease.

Widespread occurrence of AP in amyloidotic tissues. An immunohistochemical observation

Plasma (P)-component of amyloid (AP or SAP), while not an integral part of the amyloid fibril, has been considered to be intimately associated with virtually every different type of amyloid. In the present study, we evaluated the distribution of AP in the organs frequently involved in two forms of human systemic amyloidosis (AA and AF) and in mouse AA amyloidosis, by use of immunohistochemistry with anti-AP. Although the amyloid deposits generally showed moderate reactions with anti-AP, they were not always clearly distinguished from the surrounding non-amyloid tissue elements which often stained as well. The basement membrane often showed even stronger reaction to anti-AP than the adjacent amyloid deposits, and liver sections demonstrated such a high overall reaction to anti-AP that the anti-AP reaction on the amyloid deposits was often obscurred. The present results suggest that the binding between AP and the amyloid fibril may not be monospecific, that AP by this technique occurs rather widely throughout the body, and therefore that anti-AP may not be considered as specific a marker for amyloid deposits in immunohistochemical and perhaps other studies as well.

Immunocytochemical study of hepatocyte synthesis of amyloid AA. Demonstration of usual site of synthesis and intracellular pathways but unusual retention on the surface membrane

For determination of the intracellular site of synthesis and the pathways followed by amyloid protein AA, immunocytochemical localization of the anti-AA reactive substance was investigated in the livers of CBA/J mice in an acute-phase response evoked by a single subcutaneous injection of 0.5 ml of 10% casein. In the cytoplasm of the hepatocytes, the positive reaction was localized on and/or in the rough endoplasmic reticulum and the single membrane-bound vesicles, vacuoles and lamellae including the Golgi apparatus, confirming that amyloid protein AA follows the common routes of synthesis and secretion established for other proteins. The anti-AA-reactive substance was also localized on the free surface of the hepatocyte membrane, including the microvilli. The latter reaction appeared as early as but lasted at least several hours longer than its cytoplasmic counterpart, suggesting that a certain retention period exists before the release of the AA-reactive substance from the cellular surface to the free blood plasma.

Primary (AL) amyloidosis as a cause of breast masses

Amyloidosis is rarely considered in the differential diagnosis of breast masses. During the past six years, 27 women with primary (24) and multiple myeloma-associated (three) amyloidosis (AL amyloid) were evaluated at our center. In five of these patients, amyloid was demonstrated on microscopic examination of breast tissue. The clinical presentations were similar to fibrocystic breast disease in two cases and malignancy in two others. Amyloidosis of the breast may be more common than previously recognized, especially considering the predilection of amyloid for depositing around fat cells. Therefore, pathologic examination of nonmalignant breast tissue should include Congo red staining and viewing under polarized light.

Cloning of human prealbumin complementary DNA. Localization of the gene to chromosome 18 and detection of a variant prealbumin allele in a family with familial amyloid polyneuropathy

Prealbumin, a 55,000 Mr protein, is a normal constituent of human serum. In patients with familial amyloid polyneuropathy (FAP), an autosomal dominant disease, variant prealbumin molecules are found in association with systemic amyloid deposits. One variant prealbumin has a methionine for valine substitution at amino acid 30 and has been implicated in the pathogenesis of type 1 FAP. A prealbumin-specific complementary DNA clone has been isolated from an adult human liver library and used in Southern blot hybridization experiments to identify a unique NsiI restriction endonuclease site in the variant allele carried by type 1 FAP patients with the methionine for valine substitution. The complementary DNA clone has been used to analyse a panel of human-mouse and human--hamster somatic cell hybrid DNAs and localize the prealbumin gene to chromosome 18.

Nephelometric measurement of human serum prealbumin and correlation with acute-phase proteins CRP and SAA: results in familial amyloid polyneuropathy

Prealbumin, a negative acute-phase reactant, has a role as a clinical index of patient status after inflammation, trauma, or surgery that is gaining recognition. We developed a rate nephelometric assay that allows quantitation of prealbumin levels in a large number of samples to be performed quickly, efficiently, and reproducibly. The generation of data by this method is more rapid and precise than the alternative measurement techniques of radioimmunoassay, radial immunodiffusion, and electroimmunoassay. Nephelometric analysis of serum prealbumin in 33 patients with familial amyloidosis showed significantly depressed concentrations compared with levels in normal individuals and in patients with primary and secondary amyloidosis. Prealbumin levels were compared with corresponding amounts of the acute-phase proteins C-reactive protein and serum amyloid A in the three amyloid groups. Lowered prealbumin concentrations corresponded to elevated levels of C-reactive protein and serum amyloid A in the sera from patients with primary and secondary amyloidosis. In the group with familial amyloidosis, however, the lower than normal levels of prealbumin did not correspond to elevations in C-reactive protein and serum amyloid A. Our data suggest that depressed plasma prealbumin concentrations noted in individuals with familial amyloidosis are not simply reflections of a negative acute-phase response.

Colchicine in acute inflammation: stimulation of production of interleukin-1 and modulation of the acute phase serum amyloid A protein response

The effects of colchicine on the acute phase serum amyloid A (SAA) response were studied in CBA/J mice to determine whether these effects are mediated via inhibition of interleukin-1 (IL-1) production. Prolonged pretreatment (72 h) with colchicine blunted the SAA response to stimulation with silver nitrate (AgNO3), while brief pretreatment (12 h) unexpected augmented SAA production. In a macrophage model, colchicine stimulated baseline production of IL-1 (SAA inducer and lymphocyte activating factor activities) and augmented lipopolysaccharide (LPS) induced IL-1 production. This indicates that colchicine does not inhibit amyloidosis via direct effects on early inducers of the acute phase SAA response.

Heterogeneous participation of the hepatocyte population in amyloid protein AA synthesis

Amyloid protein AA is believed to be synthesized in the liver in a form of its precursor, the acute phase reactant, SAA. To identify precisely the cell involved in SAA biosynthesis, immunohistochemical reaction to anti-mouse AA was analysed on the liver sections from CBA/J mice which had received a single casein injection and were sacrificed at predetermined times up to 48 hours. Two different primary localizations of the reaction were revealed. One was in the cytoplasm of certain hepatocytes. This reaction peaked at 6-8 hours after the casein injection in the intensity of the reaction and in the number of the cells involved. The hepatocytes with positive cytoplasmic reaction were scattered over the lobule and even at the peak did not exceed 20% of the total hepatocyte population. The other localization of the reaction covered linearly the surface of the hepatocyte cords, and peaked at 12-16 hours after the casein injection.

Serum amyloid A protein concentration in progressive systemic sclerosis (scleroderma)

Serum amyloid A protein (SAA) concentrations were determined in 62 patients with progressive systemic sclerosis (PSS). Forty-seven patients had normal or slightly elevated SAA levels (less than 1000 ng/ml = micrograms/l), while 15 patients had moderately to markedly elevated SAA levels, similar to those observed in active rheumatoid arthritis (RA) (greater than or equal to 1000 ng/ml = micrograms/l). Five patients with PSS had SAA levels corresponding to those observed in amyloidosis secondary to RA. High SAA was associated with more severe skin thickening and diminished cumulative survival at five years. The rarity of amyloidosis secondary to PSS is unlikely to be related to an intrinsic defect in SAA production.

Familial amyloid polyneuropathy: a new kinship of German ancestry

Familial amyloid polyneuropathy (FAP) is an autosomal dominant inherited disorder that primarily affects the peripheral and autonomic nervous systems and usually becomes symptomatic in the third or fourth decade. Because of the confusion with other genetically transmitted neurologic conditions, the diagnosis is often delayed until advanced stages. We describe a new German kinship with FAP in which the disorder was detected in two asymptomatic family members who were seeking genetic counseling.

Localized amyloidosis of the head and neck and upper aerodigestive and lower respiratory tracts

Seven cases of localized amyloidosis limited to structures of the head and neck and upper aerodigestive and lower respiratory tracts evaluated and treated at Boston University Hospitals in a recent 7-year period were reviewed. Negative Congo red staining of abdominal adipose aspiration biopsy or rectal biopsy specimens established that the amyloidosis was not systemic. Localized amyloidosis occurred in discrete masses in a variety of sites in the aerodigestive tract including the orbit, nasopharynx, lips, floor of mouth, tongue, larynx, and tracheobronchial tree. Five patients required surgical excision because of significant airway obstruction or organic dysfunction. Amyloid deposits completely excised with the carbon dioxide laser have not recurred, though other amyloid masses may appear elsewhere within the same organ or region. Amyloidosis may occur primarily or secondarily to other disease states. Localized amyloidosis has not been chemically identified but is usually defined by the absence of systemic features. While rare, amyloidosis must be recognized and understood by the otolaryngologist/head and neck surgeon to allow appropriate diagnostic and therapeutic planning.

Hepatic amyloidosis. A histopathologic analysis of primary (AL) and secondary (AA) forms

The liver is a major site of amyloid deposition. The spectrum of histopathologic changes in the liver was studied in 38 patients with systemic amyloidosis (25 with primary or myeloma-associated amyloidosis [AL] and 13 with secondary, reactive [AA] amyloidosis). Overall architectural distortion, alterations of portal triads, as well as predilection for topographic deposition in the parenchyma and/or blood vessel walls were noted. Significant histopathologic differences in AL or AA amyloid liver involvement included 1) portal fibrosis, seen in 7 of 25 (28%) AL patients and 8 of 13 (62%) AA patients (P = 0.05), 2) parenchymal amyloid deposition in 25 of 25 (100%) AL amyloid and 10 of 13 (77%) AA amyloid patients (P = 0.04), and 3) vascular amyloid deposition found in 17 of 25 (68%) with AL amyloid and 13 of 13 (100%) patients with AA amyloid (P = 0.02). These data vary from the widely held concept that deposition of amyloid is predominantly vascular in the AL form and parenchymal in amyloid AA. Clearly, however, in individual cases significant overlap occurred, and characterization of amyloid types based on morphologic distribution of amyloid deposits may be possible in only a minority of cases. In most cases, differentiation of amyloid AL and amyloid AA forms requires clinical, histochemical, immunochemical, and sometimes more elaborate laboratory amino acid sequence studies for accurate identification.

Measurement of murine serum amyloid P component by rate nephelometry

Murine serum amyloid P component (SAP) is an acute-phase protein that is increased 2-10-fold in concentration following appropriate inflammatory or infectious stimuli. Previous studies of the acute-phase SAP response have employed quantitative immunoelectrophoresis or radioimmunoassay to measure SAP concentration. A rate nephelometric procedure has been developed which measures SAP concentration rapidly and with equivalent or greater precision than the previously applied techniques. This simple method will facilitate experimental and clinical studies of the acute-phase response.

Amyloid goiter: preoperative scintigraphic diagnosis using Tc-99m pyrophosphate

Amyloid goiter is a rare clinical entity. The diagnosis is rarely made preoperatively because clinical and laboratory findings are nonspecific. We report two cases of amyloid goiter in whom the diagnosis was made preoperatively using Tc-99m pyrophosphate scintigraphy.

Behavior modification and the treatment of myopia

Myopia is a highly prevalent disorder of vision that has traditionally been managed by means of corrective lenses. In recent years, however, there has been an upsurge of interest in the use of vision training programs as an alternative form of treatment, and particularly in the application of behavior modification techniques for the improvement of visual acuity. The most impressive experimental work to date has been in the area of operant conditioning methods (principally feedback and fading) on the modification of acuity, and this research is reviewed in depth. Also considered here are a number of relevant studies on the use of hypnosis and biofeedback training of accommodation. Research in this area is particularly timely in view of the increasing interest in the role of learning factors in both the development and maintenance of myopia. Despite a number of methodological problems identified in this review, there appears to be considerable promise in the application of behavior modification to disorders of vision.