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Biomedical subjects

M Rojkind

Publications and source records attributed to M Rojkind.

At least 19 recordsLinked to original sources
PubMed1992

Polyunsaturated lecithin prevents acetaldehyde-mediated hepatic collagen accumulation by stimulating collagenase activity in cultured lipocytes.

We recently found that polyunsaturated lecithin prevents ethanol from causing cirrhosis in the baboon. Because transformation of lipocytes to transitional cells plays a key role in hepatic fibrogenesis in vivo, and because this process in alcohol-fed baboons was found to be attenuated by polyunsaturated lecithin, we focused on lipocytes to study the mechanism of the protective effect. Rat lipocytes cultured on plastic undergo spontaneous activation, accompanied by expression of alpha-smooth muscle actin isoform and production of substantial amounts of type I collagen. The latter was further increased on incubation with acetaldehyde. This in vitro model was used here to study how acetaldehyde-mediated collagen production and accumulation can be turned off. Addition of polyunsaturated lecithin (10 mumols/L) was found to prevent the acetaldehyde-induced increase in collagen accumulation by 83% (p less than 0.001). By contrast, a saturated phospholipid (10 mumols/L dilauroyl phosphatidylcholine), a monounsaturated one (10 mumols/L linoleoyl-palmitoyl phosphatidylcholine) or linoleic acid (20 mumols/L bound to albumin) had no such effect. Incorporation of [3H]proline into collagen and the expression of alpha-1 (I) procollagen mRNA were increased by acetaldehyde; the latter was not significantly affected by polyunsaturated lecithin. Polyunsaturated lecithin increased lipocyte collagenase activity by 100% (p less than 0.001), whereas dilauroyl phosphatidylcholine, linoleoyl-palmitoyl phosphatidylcholine and linoleic acid had no such action. We concluded that (a) polyunsaturated lecithin selectively prevents the acetaldehyde-induced increase in collagen accumulation in lipocyte cultures, whereas other phospholipids or linoleate have no such effect; and (b) polyunsaturated lecithin does not modify the acetaldehyde-mediated increase in alpha-1 (I) procollagen mRNA, but it increases collagenase activity, suggesting that the protective effect exerted by polyunsaturated lecithin against alcohol induced fibrosis in vivo is due at least in part to stimulation of collagenase activity, which may prevent excess collagen accumulation by offsetting increased collagen production.

Acetaldehyde↗
PubMed1992

Fibrogenesis in cirrhosis. Potential for therapeutic intervention.

Liver cirrhosis is an end stage of several diseases that affect the liver chronically. It is characterized, among other things, by excess collagen deposition, distortion of liver architecture, tissue malfunction and hemodynamic alterations. Many of the complications of cirrhosis may result from excess matrix-deposition. Therefore, prevention of collagen accumulation or removal of collagen deposits could ameliorate the disease. In this article we discuss the pathophysiology of liver fibrosis and we describe various compounds with antiinflammatory and antifibrogenic activity. We discuss their possible mechanism of action and we describe animal and clinical studies in which these compounds have been utilized.

Animals↗
PubMed1991

Pathologic fibrosis and matrix connective tissue in the subaortic myocardium of patients with hypertrophic cardiomyopathy.

To evaluate scar-type and matrix connective tissue and to assess their role in the diastolic dysfunction of hypertrophic cardiomyopathy, surgically resected subaortic myectomy specimens and several autopsy hearts from patients with hypertrophic cardiomyopathy were studied. Eighteen specimens were differentially stained by a newly developed method that precisely determines relative collagen content; these tissues were compared with postmortem hypertrophied and normal control subaortic specimens. Quantitation revealed a 72% higher level (36.5 vs. 22.1 micrograms collagen/mg protein) of stainable collagen in the hearts with hypertrophic cardiomyopathy than in hypertrophied control hearts. The endocardial plaque was quantitated morphometrically, and it constituted only 4.6 +/- 1.7% of the total increased collagen content in the cardiomyopathy specimens. For the matrix studies, the cardiomyopathy specimens were stained by a silver impregnation technique that identifies connective tissue elements not normally visible with routine histologic methods. There was a marked increase in content of all matrix components, both in areas of pathologic scarring and in "normal" zones. Whorls of matrix connective tissue were noted in regions of myocyte whorls, as well as independent of them. Thus, these studies revealed a striking increase of both scar-type and matrix connective tissue in hypertrophic cardiomyopathy. The extensive scarring and the pronounced interstitial and intercellular matrix connective tissue may contribute to the increased ventricular chamber stiffness and impaired relaxation in this disease.

Cardiomyopathy, Hypertrophic↗
PubMed1991

Propranolol ameliorates the development of portal-systemic shunting in a chronic murine schistosomiasis model of portal hypertension.

We investigated the role of early portal hypotensive pharmacotherapy in preventing the development of portal-systemic shunting in a portal hypertensive model of chronic murine schistosomiasis induced by infecting C3H mice with 60 cercariae of Schistosoma mansoni. Propranolol was administered in drinking water to 20 animals for a period of 6 wk at a dose of 10 mg.kg-1d-1, starting at 5 wk of schistosomal infection. 32 age-matched mice with chronic schistosomal infection served as controls. All animals were studied 11 wk after the infection. Compared with controls the portal pressure (10.8 +/- 0.40 mmHg) was significantly lower (P less than 0.001) in the propranolol-treated animals (7.9 +/- 0.80 mmHg). Portal-systemic shunting was decreased by 79%, from 12.2 +/- 3.34% in controls to 2.5 +/- 0.99% in the propranolol group (P less than 0.05). Portal venous inflow was reduced by 38% in the propranolol treated animals (2.50 +/- 0.73 ml/min; n = 6) compared with controls (4.00 +/- 0.34 ml/min; n = 8; P less than 0.05). The worm burden, the granulomatous reaction, the collagen content of the liver, and the serum bile acid levels were not significantly different between the two groups of animals. These results demonstrate that in chronic liver disease induced by schistosomiasis, the development of portal-systemic shunting can be decreased or prevented by the reduction of flow and pressure in the portal system.

Animals↗
PubMed1991

Characterization of fat-storing cell lines derived from normal and CCl4-cirrhotic livers. Differences in the production of interleukin-6.

Liver fat-storing cells (FSC) play an important role in collagen deposition. During the induction of liver cirrhosis, FSC lose their fat droplets, acquire an actin-rich cytoskeleton and transform into myofibroblasts. Myofibroblasts have been associated with increased collagen production in cirrhotic livers. Cultured FSC resemble myofibroblasts. However, it is not known whether regulation of collagen gene expression is similar in FSC obtained from normal or cirrhotic livers. In this communication, we describe the characterization of two fat-storing cell lines, one from normal (NFSC) and one from CCl4-cirrhotic liver (CFSC), obtained after spontaneous immortalization in culture. We studied the effect of serum and various growth factors on cell proliferation. We determined the production of collagen and fibronectin and we analyzed the presence of mRNA transcripts of collagens type I, III, and IV, fibronectin laminin, transforming growth factor-beta and interleukin-6. We found that CFSC have a greater serum-dependency than NFSC. NFSC grow with a mixture of insulin and epidermal growth factor, whereas CFSC proliferate only with platelet-derived growth factor. Although we did not find significant differences in the expression of mRNAs for collagen type I, fibronectin and transforming growth factor-beta, collagen and fibronectin synthesis was increased 2- and 1.5-fold respectively. NFSC contained 1.6- and 2.0-fold more type III collagen and laminin mRNAs, respectively, than CFSC. Neither cell line expressed type IV collagen mRNA. NFSC but not CFSC produced interleukin-6. These results suggest that, except for the lack of transcripts of collagen type IV, both cell lines resemble primary cultures of FSC. However, significant differences in cell proliferation and interleukin-6 production between the two cell lines were found. We suggest that these cell lines could be useful tools to study possible differences in regulation of matrix production by FSC.

Adipose Tissue↗
PubMed1991

Regulation of collagen production in freshly isolated cell populations from normal and cirrhotic rat liver: effect of lactate.

Previous work has shown that lactic acid, and to a lesser extent pyruvic acid, is able to increase collagen synthesis significantly in liver slices of CCl4-treated rats but not normal rats. The purpose of this report is to document which cells in the cirrhotic liver are responsible for the lactate-stimulated increase in collagen synthesis. It was found that (a) incorporation of 3H-proline into protein-bound 3H-hydroxyproline is increased threefold to fourfold in hepatocytes from CCl4-treated rats as compared with normal rat hepatocytes; (b) neither the hepatocytes from normal nor those from CCl4-treated rats modify their collagen synthesizing capacity when 30 mmol/L lactic acid was added to the incubation medium; (c) nonparenchymal cells obtained from livers of CCl4-treated rats synthesize much less collagen than hepatocytes, but their synthesis is stimulated twofold by lactic acid; (d) from the different nonparenchymal cells, only fat-storing (Ito) cells increase collagen synthesis when lactic acid is present in the incubation medium. These results suggest that the increased lactic acid levels observed in patients with alcoholic hepatic cirrhosis may play an important role in the development of fibrosis by stimulating collagen production by fat-storing (Ito) cells.

Animals↗
PubMed1991

Acetaldehyde increases procollagen type I and fibronectin gene transcription in cultured rat fat-storing cells through a protein synthesis-dependent mechanism.

We previously reported that acetaldehyde increases the production of type I collagen in cultured rat fat-storing cells. We studied the regulation of this effect by determining the expression of procollagen type I, fibronectin and transforming growth factor-beta 1 messenger RNAs in passage 1 and 2 cultures of fat-storing cells exposed to acetaldehyde for up to 24 hr. By 6 hr, acetaldehyde increased the steady-state levels of alpha 1 procollagen type I messenger RNA 3.2-fold and of fibronectin messenger RNA 2.8-fold above control values. At 24 hr, messenger RNA levels remained elevated. In contrast, transforming growth factor-beta 1 messenger RNA steady-state levels remained unaltered by 6 hr, but increased 1.5-fold by 24 hr. Cycloheximide (0.3 mmol/L) completely inhibited the acetaldehyde effect when added at zero time but was less effective when added at 15 min. The effect of acetaldehyde was not modified when cells were cultured in the presence of the acetaldehyde dehydrogenase inhibitor cyanamide (100 mumol/L). Fat-storing cells were also cultured in the presence of lactate (5, 15 and 25 mmol/L) for 6 hr. At none of these concentrations was any effect seen on either alpha 1(I) procollagen or fibronectin messenger RNAs. In the presence of methylene blue, a scavenger of reducing equivalents, the effect of acetaldehyde on alpha 1(I) procollagen and fibronectin gene expression was totally inhibited. Transcription run-on assay showed that acetaldehyde increased both procollagen type I and fibronectin transcriptional activity threefold and 2.5-fold, respectively. We conclude that acetaldehyde increases alpha 1(I) procollagen and fibronectin gene expression through enhanced transcription by a mechanism dependent on newly synthesized proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetaldehyde↗
PubMed1990

Hemodynamic mechanisms of emerging portal hypertension caused by schistosomiasis in the hamster.

A hamster model of schistosomiasis has provided the first opportunity to sequentially examine the early phases of the development of portal hypertension in a natural model of chronic liver disease. Groups of hamsters were infected with 50 cercariae of Schistosoma mansoni and underwent hemodynamic evaluation at intervals of 5, 8, 12 and 20 wk after infection. A progressive rise in intrahepatic resistance (from 4.0 +/- 0.4 to 8.4 +/- 1.0 mm Hg min.ml-1.gm liver weight [p less than 0.01]) appeared to play a major role in the initial stages of evolving portal hypertension. A gradual decline in portal blood flow (from 2.1 +/- 0.3 to 1.3 +/- 0.1 ml.min-1.gm-1 liver weight [p less than 0.01]) was only partially compensated for by an increase in hepatic arterial flow. Accordingly, by week 20, total hepatic blood flow decreased 23%. Liver weight that increased markedly between 5 and 12 wk after infection, as a result of the acute accumulation of obstructing granulomas, stabilized between wk 12 and 20, while a gradual but progressive rise in hepatic collagen content was seen. Portal pressure increased 75% during the study period. Chronic examination of this natural model should help define the pathogenesis of the complications of portal hypertension and contribute to the basis for effective intervention in this disease process.

Animals↗
PubMed1990

Effect of colchicine on lymphocyte and monocyte function and its relation to fibroblast proliferation in primary biliary cirrhosis.

Lymphocyte and monocyte function was investigated in eight patients with primary biliary cirrhosis and in age-matched and sex-matched controls. In three of the eight cirrhotic patients, two were in the late stage of the disease (stage III) and concanavalin A-induced suppressor cell function was markedly decreased; it returned to normal levels after 1 mo of treatment consisting of 5 mg per week of orally administered colchicine. The relative percentage of T cell subsets (CD3, CD4 and CD8) and the mean percentage of the helper and the suppressor phenotype were similar in cirrhotic patients and in controls. Basal production of interleukin-1 activity by a monocyte-enriched fraction of peripheral blood mononuclear cells of cirrhotic patients was three-fold above control values: after stimulation with endotoxin, interleukin-1 values increased tenfold above basal levels in monocyte-enriched fraction of peripheral blood mononuclear cells of both normal and cirrhotic patients. Colchicine normalized the basal production of interleukin-1 and inhibited its stimulation by endotoxin by 50%. Culture supernatants of endotoxin-stimulated monocyte-enriched fraction of peripheral blood mononuclear cells increased the proliferation of cultured human skin fibroblasts by 50%. In contrast, supernatants from stimulated monocyte-enriched fraction of peripheral blood mononuclear cells obtained from colchicine-treated patients significantly inhibited fibroblast proliferation. These findings suggest that stimulated chronic inflammatory cells may play an important role in liver fibrosis. Some of the actions of colchicine could be related to its effects on lymphocyte and monocyte function.

Adult↗
PubMed1989

Serum type III procollagen peptide and laminin (Lam-P1) detect alcoholic hepatitis in chronic alcohol abusers.

The diagnosis of alcoholic hepatitis is difficult to establish by conventional clinical and laboratory methods, and a firm diagnosis relies on liver histology. Since there are severe limitations in following patients with repeated liver biopsies, noninvasive procedures are needed to assess the presence of alcoholic hepatitis in chronic alcohol abusers. It has been suggested that serum Type III procollagen peptide levels correlates with the degree of inflammation in chronic liver disease. Since inflammation is a major histological finding in alcoholic hepatitis, we therefore studied the usefulness of measuring serum Type III procollagen peptide and laminin values in 45 consecutive chronic alcohol abusers, with or without cirrhosis, in detecting those with alcoholic hepatitis. The results showed that both Type III procollagen peptide and laminin values were elevated in all of the patients with established liver damage. However, the values were highest in those with liver cirrhosis plus alcoholic hepatitis (Type III procollagen peptide 50.4 +/- 36.4 ng per ml vs. 8.1 +/- 2.6 in controls, p less than 0.01; laminin 4.50 +/- 1.49 units per liter vs. 1.24 +/- 0.26 units per liter in controls, p less than 0.01), followed by subjects with alcoholic hepatitis alone (Type III procollagen peptide 23.5 +/- 17.6 ng per ml, p less than 0.01; laminin 2.60 +/- 1.09 units per liter, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Kupffer cells from CC1(4)-treated rat livers induce skin fibroblast and liver fat-storing cell proliferation in culture.

Conditioned media of Kupffer cells from normal rat liver produce in culture two factors that inhibit fibroblast proliferation. The inhibitory factors have molecular masses of approximately 25 and 5 kDa. In contrasts to these results, the conditioned media of Kupffer and mononuclear macrophagic cells, obtained 48 hours after CC1(4) administration to rats, contains a 17 kDa factor that stimulates fibroblast proliferation (FSF). FSF also stimulates [3H]-thymidine incorporation into DNA of cultured rat liver fat-storing cells. Two peaks with FSF activity were demonstrated after isoelectrofocusing; one with a pI of 6.1 and a second with a pI of 7.5. The fraction containing FSF is devoid of interleukin-1 (IL-1) activity and no inhibitory activity is detected in this conditioned media. Production of FSF is inhibitable by colchicine but not by indomethacin, it is thermolabile and trypsin-sensitive. In animals treated chronically with CC1(4) to produce cirrhosis, FSF activity is demonstrable from the first to the 8th week of treatment. However, the activity is lower at 8 weeks post-CC1(4) as compared with 2 weeks. The results suggest that homeostasis of cells in the liver is controlled by factors produced locally, that act by autocrine and paracrine mechanisms. When homeostasis is altered, fibroblast proliferation occurs, and excess collagen deposition leads to fibrosis. We propose that the antifibrogenic activity of colchicine is associated, in part, with its capacity to inhibit the release of FSF by Kupffer cells and liver mononuclear macrophage cells.

Animals↗
PubMed1989

Resistance to reinfection in experimental murine schistosomiasis: role of porto-hepatic hemodynamics.

Experiments were conducted to evaluate critically, and independently of the immune system, the possible role of hemodynamic mechanisms in resistance to schistosomal reinfection. The effects of a challenge schistosomal infection were compared in groups of mice which were either previously infected with schistosomiasis, vaccinated with irradiated cercariae, or underwent partial portal vein ligation for the induction of portal hypertension and porto-systemic shunting. Following infection with 60 cercariae, the appearance of portal hypertension preceded by approximately 2 weeks the development of porto-systemic shunting, which reached maximal values 11 weeks postinfection. Such a primary infection conferred on C3H mice an estimated 90% protection to a 2nd infection, measured by the reduction of worm burden. Worm burdens were also reduced in vaccinated and ligated animals as compared to normal controls. The protection amounted to 30% and 56%, respectively, in the C3H strain and 63% and 75-85%, respectively, in the C57Bl/6 strain. Reduction in worm burden in the ligated animals is believed to be due to the extrahepatic porto-systemic vascular shunts. Hemodynamic as well as immunological factors may account for the resistance to reinfection observed in chronic murine schistosomiasis.

Animals↗
PubMed1988

Colchicine in the treatment of cirrhosis of the liver.

There is preliminary evidence that colchicine, an inhibitor of collagen synthesis, may be beneficial in the treatment of cirrhosis of the liver. To evaluate the use of colchicine (1 mg per day, five days per week) in the treatment of hepatic cirrhosis, we performed a randomized, double-blind, placebo-controlled trial in which 100 patients were followed for up to 14 years. Forty-five patients had alcoholic cirrhosis, 41 had posthepatitic cirrhosis, and the remaining 14 had cirrhosis with various other causes. Histologic studies were available for 92 percent of patients. Seventy-three patients were in Child-Turcotte class A, 26 were in class B, and one was in class C. Fifty-four patients received colchicine, and 46 received placebo. The overall survival in the colchicine group was markedly better than in the placebo group (median survival, 11 and 3.5 years, respectively; P less than 0.001). The cumulative 5-year survival rates were 75 percent in the colchicine group and 34 percent in the placebo group; the corresponding 10-year survival rates were 56 percent and 20 percent. Among the 30 patients treated with colchicine who underwent repeated liver biopsies, histologic improvement was seen in 9; the liver appeared normal in 2, and 7 had minimal portal fibrosis. No histologic improvement was observed in the 14 members of the placebo group who had two or more biopsies. Few side effects were observed in either group.

Clinical Trials as Topic↗
PubMed1988

Immunohistochemical micromethods for the measurement of specific collagen types in human liver biopsies.

Micromethods are needed for measuring the amount of collagen and other matricial proteins in human liver biopsies. Recently, a colorimetric method for the quantitative estimation of total collagen and protein has been developed. This method is sensitive, can be applied to fresh and fixed tissues and provides the absolute value of total collagen per section. Results are expressed as microgram of collagen per mg of proteins or per section. We now report two micromethods for the determination of specific collagen types in fresh frozen liver sections. The first method is a direct method utilizing the tissue section as an ELISA plate. Results are expressed as the amount of color reaction read at 450 nm per slide. After cleaving the antigen antibody complex with dilute acetic acid, the amount of total collagen can be measured by the colorimetric microchemical method and the amount of specific collagen type is expressed as the amount of color reaction per microgram of total collagen. The second method is an indirect method: the floating tissue section is incubated with an optimal amount of specific anti-collagen antibody and the residual amount of antibody present in the supernatant is measured in an ELISA plate coated with the specific collagen type. The amount of specific collagen type present in the tissue section is determined by comparing the optical deviation obtained with a standard curve prepared with known amounts of specific collagen, and values are expressed as microgram of collagen per tissue sections. As with the direct method, the amount of total collagen per section can be measured by the colorimetric method and then, the amount of specific collagen type can be expressed as microgram of specific collagen type per microgram of total collagen.

Biopsy, Needle↗
PubMed1988

Lipid quantitation in formalin-fixed liver sections.

We describe a simple, sensitive, and quantitative procedure for measurement of triglycerides and protein contents in formalin-fixed liver sections. The method can detect as little as 0.27 microgram of triglycerides per mg of protein. It is based on selective binding of Sudan IV and Fast Green FCF to fat and total proteins, respectively, and their sequential elution with solvents. Sudan IV is eluted readily with acetone and Fast Green with NaOH-methanol, and the absorbances obtained at 500 and 610 nm can be used to determine the amount of triglycerides and total protein. The color equivalence for Fast Green was obtained after destaining the sections and measuring the protein contents by micro-Kjeldahl analysis. The color equivalence of Sudan IV was estimated by determining the triglyceride content in liver homogenates by an enzymatic procedure and then measuring the amount of dye bound to multiple fixed sections. There was a strong linear correlation between the triglyceride content as determined chemically and that obtained using the equivalence colors (r2 = 0.98). This method is useful to measure fat content in tissue samples and could be applied to evaluate the progression of liver disease.

Animals↗