Irreversible liver cirrhosis was induced in rats by supplementing their diet with 0.02% azathioprine and intubating them twice a week with carbon tetrachloride in corn oil. Over period of 3 mo, intoxicated rats showed an atypical acute-phase reaction (APR). The relative concentrations of haptoglobin, beta-lipoprotein, alpha-1-antitrypsin, an unknown peak "X, " and transferrin increased exponentially following a mild initial drop, while albumin, C3c + C3, alpha-1-acid glycoprotein, alpha-1-lipoprotein, and macroglobulin declined continually during the experiment. The accumulated peritoneal fluid was found to contain a similar spectrum of APR proteins. On the other hand, histological examination revealed gradual liver damage manifested as a gradual increase in the areas of collagen separating liver cells, and at the end of the experiment, severe liver damage was evident with isolated hepatocytes in a matrix of collagen. The available data point to the disparity that exists between the physical status of hepatocytes and their biochemical function, which suggests that the remaining metabolically fatigued hepatocytes of the cirrhotic liver continue to biosynthesize and release elevated concentrations of some secretable APR proteins and less of others. Changes in the spectrum of APR plasma components during the progression of inflammatory or physical lesion remain a valid biochemical measure of the pathological function of the acutely intoxicated liver. Partial hepatectomy (PH) of cirrhotic liver displayed a mute APR and no regenerative activity of the remnant hepatic tissue, most likely due to the substantial depletion of hepatic DNA and possible chemical damage to DNA of the remaining viable hepatocytes. A possible cause for the depressed APR to the surgical insult of PH is that the initial azathioprine-CCl4 intoxication had maximally affected APR gene expression and a second injury would then elicit minimal further changes in mRNA levels. Thus, in a compounded pathological condition, the initial inflammatory stimulus on various pre-rRNAs, rRNAs, and mRNAs is rate-limiting to the hepatic biosynthesis and secretion of APR proteins and may not respond linearly, if at all, to a second stimulus.

A useful framework is proposed for unifying the synthesis of plasma proteins and their degradation by, or release from, liver cells of intact and partially hepatectomized rats, in which synthesis and release of acute-phase plasma proteins occur in synchrony with the internalization and catabolism of plasma and extracellular proteins. The catabolism of proteins and other hepato-intracellular glycoproteins during sepsis or trauma is essential to provide constituent amino acids and carbohydrates for the synthesis of acute-phase plasma proteins. Increases in the plasma levels of acute-phase response proteins in sham-operated rats reached a maximum between 1 and 2 d after mock surgery, and had returned virtually to control levels within 6 d. By contrast, acute-phase proteins in the plasma of partially hepatectomized rats were decreased by 10-20% of their initial values after 24 h. A maximum acute-phase response on d 7 after the operation was characterized by an increase of 181, 445, and 19% for alpha-1-acid glycoprotein, hepatoglobin, and hemopexin, whereas other acute-phase proteins remained below control levels, for example, by 11, 25, and 38% for albumin, transferrin, and prealbumin, respectively. This delayed response suggests that the nascent liver cells had inherited the capacity of the parent cells to respond to inflammatory signal and had synthesized acute-phase plasma proteins. Accordingly, a time frame for the application of toxin to nascent hepatocytes is suggested. An increased activity (300 +/- 50%) for both bound and free neuraminidase in remnant liver tissue 19 h post partial hepatectomy suggested that hepatic regenerating factor(s) were produced in liver tissue via the hepatic bound and/or free neuraminidase-mediated desialylation of humoral substrates. By contrast, circulating levels of lysosomal enzymes alpha-fucosidase and beta-N-acetyl-D-glucosaminidase were increased marginally after 24 h but had returned nearly to control levels after 7 d, suggesting that lysosomal acid hydrolases do not play a major role in regenerative DNA synthesis, mitosis, or in the synthesis of acute-phase plasma proteins.

The aim of the present study is twofold: to establish the response of hepatic machinery of plasma protein biosynthesis to cholera intoxication, and to examine the same response of alloxan-diabetic hepatocytes with minimal capacity of synthesis of plasma proteins. Direct lesion of hepatic plasma membranes via ip administration of cholera toxin to male rats resulted in a typical acute-phase response (APR) of plasma proteins, which had regressed to levels similar to those of healthy controls approximately at 240 h postintoxication. The d 2 response to a single 0.16 mg/kg body weight dose was typified by a 23% reduction in the level of albumin, but a 6- and 24-fold increase in the levels of fibrinogen and alpha-1-acid glycoproteins, respectively. This response was similar (in direction but not in magnitude) to the acute-phase reaction to a simple subcutaneous administration of carrageenan. The intoxication was accompanied by a massive leakage, into the peritoneal cavity, of plasma fluid, which embraced the complete profile of acute-phase reactants. A three-step mechanism is proposed to account for the observations as follows: (1) There is a rapid formation of a stable complex between subunit B of the toxin and ganglioside GM1 of hepatic plasma membrane. An APR is induced in response to the alteration(s) of hepatic plasma membranes. (2) The release, from the choleragen-membrane complex, of polypeptide A1 and its subsequent penetration of the hepatic membrane result in both activation of adenylate cyclase and increased vascular permeability of hepatic membranes. This leads, in turn, to exudation of components of plasma fluid in the peritoneal cavity of intoxicated rats. An alternate rationale for this exudation is the slow leakage of plasma proteins out of the blood vascular system (possibly through microvesicles) into the peritoneal cavity of cholera intoxicated rats. The spectrum of acute-phase hepatic secretory components was mirrored in the corresponding peritoneal exudate. (3) The increased hepatic membrane flow provides the continued renewal of plasma membrane proteins required for its eventual repair by either endocytosis or sloughing off the toxin-bound membrane segments into the circulatory system, thus producing regression of APR. Livers of diabetic rats, an already established model in terms of APR, responded to ip administration of cholera toxin by increased biosynthesis of the identified plasma proteins and a marked reduction in total free-glucose in serum.(ABSTRACT TRUNCATED AT 400 WORDS)

Naturally occurring glycoproteins have been extracted from fundic and antral mucosal tissue of the hog stomach by means of nondegrading techniques. Major and retarded glycoprotein fractions separated by gel filtration were further dissociated from appreciable amounts of noncovalently bound proteins by CsCl density gradient centrifugation. Antisera to glycoprotein fractions of fundic and antral regions of the stomach were prepared in rabbits. The major fractions from both gastric regions have similar molecular mass (approximately 2 x 10(6)), sedimentation coefficient (approximately 31.5 s), and specific viscosity (approximately 1.6). Purified fractions from each region were further separated into two subfractions by affinity chromatography on wheat germ lectin. Glycoprotein subfractions from antrum and fundus differ appreciably in their carbohydrate and amino acids content, share antigenic determinants, but do not cross-react with anti-hog serum protein antisera. Further diversity in native mucin glycoproteins was observed by the use of one-(D) and two-dimensional (2D) immunoelectrophoresis; subfractions that cross-react with specific anti-hog gastric glycoproteins were found to contain three or more components. D-Immunoelectrophoretic analyses demonstrated (1) in vivo degradation of glycoprotein components of the major fundic fraction isolated from mucosal tissue of alcohol/acetyl salicylate-intoxicated hog stomachs and (2) in vitro catabolism of major fundic glycoproteins by corresponding mitochondrial lysosomal (ML) acid hydrolases. Furthermore, 2D-immunoelectrophoretic analyses showed that (1) hog synovial fluid and plasma proteins have similar prosthetic moieties as either reacted with anti-hog serum proteins antisera. Nonetheless, locations, shapes, and staining intensities of the immunoprecipitate lines differed, which is indicative of different structures of the carbohydrate moieties of components of synovial fluid and plasma proteins, and (2) only a minor fraction of hog cerebrospinal fluid cross-reacted with anti-hog serum protein antisera. This is contrary to the generally accepted deduction based on high-resolution 2D-electrophoresis, indicative of different compositional patterns of plasma and cerebrospinal fluids.