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We describe a case of primary cardiac lymphoma diagnosed by transvenous biopsy under fluoroscopic and transthoracic echocardiographic guidance. A 38-year-old man was admitted because of exertional dyspnea. ECG revealed complete atrioventricular block. Transthoracic echocardiography revealed a large mass attached to the interventricular septum and protruding into the right atrium. The patient underwent a right heart catheterization and a biopsy was taken from the mass using fluoroscopic and transthoracic echocardiographic guidance. Diagnosis of malignant lymphoma was established by the biopsy specimen. The use of transthoracic echo in conjunction with fluoroscopy may be useful for the diagnosis of intracardiac mass transvenously.

Hypokalemic paralysis due to licorice consumption is extremely rare, with only 40 cases in the English literature describing paralysis secondary to exposure to licorice in candies, medications, chewing tobacco, and herbal preparations. We describe a patient who suffered life-threatening hypokalemic paralysis caused by consumption of licorice in the form of a tea sweetener superimposed on long-term consumption of licorice candy. Aggressive fluid and potassium replenishment produced complete and lasting recovery. To our knowledge, this is the first report of hypokalemic paralysis due to exposure to licorice as a tea sweetener, a common custom among the Arab population. The case emphasizes the importance of considering patients' cultural backgrounds and local customs, which often may lead the treating physician to the correct clinical diagnosis.

Objective: To study the prevalence and the clinical characterisation of jaw problems in patients with giant cell arteritis (GCA). Methods: the prevalence of such symptoms in patients with GCA was evaluated by performing a retrospective analysis of all patients with GCA and polymyalgia rheumatica who were diagnosed during admission to Hadassah University Hospital. Ten patients reported previously in the literature were also evaluated. Results: Six patients out of 88 (6.8%) had complaints of reduction in jaw opening. These six patients seemed to have a much more abrupt onset of disease with shorter duration until diagnosis, higher prevalence of eye involvement (50% v 27%), and a higher rate of positive pathology (100%). Conclusions: Reduction in jaw opening in the appropriate setting may indicate the presence of GCA. This sign should not be overlooked in the presence of the claudication sign as it seems to reflect more severe GCA disease.

Iloprost therapy improved distal extremity lesions and renal function in patients with cholesterol emboli syndrome Cholesterol emboli syndrome is a disorder in which multiple cholesterol crystals dislodge from atherosclerotic plaques, either spontaneously or after vascular interventions, treatment with anticoagulation, or thrombolytic treatment. The syndrome typically presents with painful ischaemic skin lesions, livedo reticularis, and acute renal failure. Treatments such as aspirin, statins, discontinuation of anticoagulation, and surgical correction of the embolic source are of limited efficacy. 1 2 We report four cases of cholesterol emboli in which treatment with iloprost, a prostacyclin analogue,3 improved both ischaemia of the distal extremities and renal failure. Four patients who had had a myocardial infarction and underwent procedures including coronary angiography, coronary bypass grafting surgery, and intra-aortic balloon pump implantation (table) presented within …

Background Heparanase modulates the level of heparan sulfate proteoglycans (HSPGs) which have an important role in multiple cellular processes. Recent studies indicate that HSPGs have an important function in hepatic lipoprotein handling and processes involving removal of lipoprotein particles. Principal Findings To determine the effects of decreased HSPGs chain length on lipoprotein metabolism and atherosclerosis, transgenic mice over-expressing the human heparanase gene were studied. Hepatic lipid uptake in hpa-Tg mice were evaluated by giving transgenic mice oral fat loads and labeled retinol. Sections of aorta from mice over-expressing heparanase (hpa-Tg) and controls (C57/BL6) fed an atherogenic diet were examined for evidence of atherosclerosis. Heparanase over-expression results in reduced hepatic clearance of postprandial lipoproteins and higher levels of fasting and postprandial serum triglycerides. Heparanase over-expression also induces formation of fatty streaks in the aorta. The mean lesion cross-sectional area in heparanase over-expressing mice was almost 6 times higher when compared to control mice (23,984 µm2±5,922 vs. 4,189 µm2±1,130, p

The expression of lipoprotein lipase mRNA (LPL mRNA) was studied in rat hearts by use of a sulfur-35-labeled antisense mRNA probe. Rats were studied under three conditions: fed, fasted, and injected with cholera toxin (an irreversible agonist of adenylate cyclase) and then fasted. The highest LPL activity was found in the hearts of cholera toxin-injected, fasted rats. After injection of cholera toxin, LPL mRNA levels were 3.5-fold higher than those from fed rats. Using in situ hybridization, we studied the site of expression of LPL mRNA under the same three experimental conditions. In sections of hearts from cholera toxin-injected, fasted rats, concentrations of autoradiographic grains, representing the site of LPL mRNA, were seen over interstitial elements, which comprise capillary and perivascular cells. A more diffuse and sparse reaction was seen over cardiac myocytes and was not always distinguishable from background. A similar but much less definitive localization was seen in sections of hearts from fasted rats. The present results indicate that in the rat heart, the main site of LPL synthesis and processing, especially after stimulation with an irreversible agonist of adenylate cyclase, is localized to interstitial elements rather than to adult cardiac myocytes.

The effect of human recombinant interleukin-1 (IL-1) on the regulation of lipoprotein lipase (LPL) was studied in rat heart mesenchymal cell cultures. A time-dependent reduction in enzyme activity occurred with a 30% fall after 1 h. The suppression of enzyme activity was accompanied by a commensurate reduction in enzyme mass. The reduction in LPL activity was most prominent in the heparin releasable pool; IL-1 treatment resulted in a 7.2-8.3-fold decrease in the functional compartment and a 2.5-2.8-fold decrease in residual cellular activity. The effect of IL-1 could be prevented by the addition of the IL-1 inhibitor. However, in contradistinction to the effect of tumor necrosis factor (TNF), there was no change in LPL mRNA in cultures treated with IL-1. The present results show that the regulation of LPL in mesenchymal heart cell cultures by IL-1 occurs posttranscriptionally, as has been shown in 3T3 cells. The more pronounced effect on LPL activity in the functional pool suggests that IL-1 treatment might have influenced also the processing and/or transport of the enzyme to the cell surface.

Adipose tissue lipoprotein lipase activity was measured in eight non-smokers and 17 smokers on fasting and four hours after oral glucose load. Fasting LPL activity was higher in the smokers when corrected for cell weight. Four hours post oral glucose load, a two fold increase in enzyme activity in the non-smoking subjects was observed while in the smokers, a 30% reduction occurred. The degree of reduction of adipose tissue LPL activity negatively correlated with the insulin release in response to the oral glucose. It is suggested that the reduction in adipose tissue LPL activity after oral glucose accounts for the reduced body weight observed in smokers. This reduction reflects a relative insulin resistance of smokers’ adipose tissue. The later may be developed due to the known increase in catecholamine in smokers.

Among 72 patients with Behçet's syndrome, seven had pulmonary vascular involvement. Additional data from 42 cases in the literature are discussed. Recurrent episodes of dyspnea, cough, chest pain, and hemoptysis were the primary clinical signs, mainly in young men, appearing 3.6 years after the first manifestation of Behçet's syndrome. Fever, elevated ESR, and anemia were common, and chest x-ray films showed pulmonary infiltrates, pleural effusions, and prominent pulmonary arteries. Ventilation-perfusion scans showed perfusion defects even when chest x-ray films were normal. Pulmonary artery aneurysms were seen in 7/13 in whom angiography was done. Of 42 patients, 16 died, 15 from fatal pulmonary hemorrhage, 80 percent within two years from the development of pulmonary disease. Histopathologic study results showed vasculitis of pulmonary vessels of various sizes, leading to thrombosis, destruction of the elastic laminae, aneurysms, and arteriobronchial fistula. In addition, pulmonary emboli and the aphthous lesion of the tracheobronchial tree may aid the clinical picture. Anticoagulant therapy may be hazardous in patients with aneurysmal dilatation of the pulmonary vascular tree, and the beneficial effect of corticosteroid therapy is discussed. Pulmonary vasculitis in Behçet's syndrome is a unique clinical and pathologic picture, differing from other vasculitides affecting the lung, presents a major threat to the patient's life.

In the present study, an attempt was made to quantify free cholesterol transfer from lipolyzed VLDL to HDL, blood cells and heart cells. The experiments were carried out in vitro or in the isolated perfused rat heart with rat plasma VLDL labelled biosynthetically with [14C]-palmitic acid and [3H]cholesterol, and with bovine milk lipoprotein lipase, human blood cells (erythrocytes, leucocytes and platelets) or rat plasma HDL. Exchange and transfer of free cholesterol was followed by radioactivity and specific activity determinations. The study demonstrated an exchange of free cholesterol between VLDL and blood cells (6–10 h) and VLDL and HDL (120 min). However, none of the blood cells tested served as acceptor for lipolysis-generated free cholesterol, whereas HDL did. In the isolated perfused rat heart, a maximum of 25% of the free cholesterol radioactivity lost from VLDL was found in the tissue. Since exchange must have contributed to this process, the transfer of free cholesterol molecules to the heart is necessarily lower. The study thus demonstrated minimal or possibly no net transport of free cholesterol from VLDL to cells and cell membranes.

Rat mesenteric duct chylomicrons and plasma very low density lipoproteins were labeled by biotransfer with [ 3 H]cholesteryl linoleyl ether and [ 14 C]cholesteryl linoleate. Following intravenous injection into rats, 50% of labeled chylomicrons were cleared from the circulation in 5 min and the ratio of both labels in the plasma and liver was similar to the injected material. The chylomicrons labeled with radioactive cholesteryl linoleyl ether were injected into rats on the 4th day postpartum and about 3% of the injected label were recovered in the lactating mammary gland. When the labeled chylomicrons were injected into postpartum rats that had been separated from their litters for 24 h the uptake of labeled cholesteryl linoleyl ether by the mammary glands was very low and did not exceed 0.2% of injected dose and was not different from the uptake by virgin mammary glands. Small mesenteric duct chylomicrons and plasma VLDL served as cholesteryl linoleyl ether donors, in analogy to large chylomicrons. The uptake of cholesteryl linoleyl ether by lactating mammary glands was related to the activity of lipoprotein lipase of the mammary tissue, which was high in suckled and low in unsuckled rats. However, this correlation became apparent only above a certain threshold of lipoprotein lipase activity which in the present experiments was about 200 nmol fatty acid released/mg acetone per h. The present findings indicate that high local activity of lipoprotein lipase promotes cellular uptake of lipoprotein cholesteryl ester, as studied presently with the help of cholesteryl linoleyl ether, a nondegradable analog of cholesteryl linoleate.

In this study, a correlation was sought between the circulating lipoprotein lipase activity and nutritional state in the rat. In fed rats, the plasma lipoprotein lipase activity was between 30 and 120 munits/ml, whereas after an overnight fast in restraining cages, the lipoprotein lipase plasma levels were between 280 and 500 munits/ml. The plasma lipoprotein lipase activity was inhibited by a specific high titre goat antiserum to rat lipoprotein lipase. No effect of fasting was seen on the plasma hepatic triacylglycerol lipase. 6 h after fasting, adipose tissue lipoprotein lipase decreased maximally, but plasma lipoprotein lipase was not changed and rose only after 16 h. Thus, it seems that most of the lipoprotein lipase activity in the fasting plasma was related to the 3-fold rise in lipoprotein lipase activity in the heart, which may represent total muscle lipoprotein lipase. The increase in heart lipoprotein lipase was due in part to an increase in the t 1 2 of the enzyme from 1.2 to 2.9 h. To determine whether the high plasma levels in the fasting rats might result from impaired clearance of the enzyme by the liver, functional hepatectomy was carried out. 15 min after hepatectomy, plasma lipoprotein lipase rose up to 20-fold in fed and about 6-fold in fasting rats. Lipoprotein lipase activity extracted by the liver was calculated to be 30–60 munits/ml in the fed and 171–247 munits/ml plasma per min in fasting rats. An increase in lipoprotein lipase activity in extrahepatic tissues (heart, lung, kidney, diaphragm and adrenal) occurred 30 min after hepatectomy in fed rats. The increase in heart lipoprotein lipase was due to an increase in heparin-releasable fraction. Since no impairment of hepatic clearance of circulating plasma lipoprotein lipase was found, the high fasting plasma lipoprotein lipase activity may be related to an increase in enzyme synthesis, decreased enzyme turnover and an expansion of the functional pool in tissues such as the heart and probably muscle. The present findings indicate that measurement of endogenous plasma lipoprotein lipase can provide information with respect to the size of the functional pool under normal and pathological conditions.

Radioiodinated lipoprotein lipase, isolated from bovine milk (125I-labeled milk lipoprotein lipase) was shown to retain full hydrolytic activity towards its native substrate, i.e., chylomicron triacylglycerol. The 125I-labeled enzyme interacted with various cells in culture by being bound to the cellular surface, internalized and degraded. Cellular binding of the labeled enzyme occurred in the presence or absence of substrate and was related to enzyme concentration. Heparin reduced cellular binding by 50% but inhibited uptake and degradation more extensively. Cellular uptake was not affected by chloroquine or NH4Cl, but degradation of the labeled enzyme was blocked. Uptake and degradation were not inhibited by mannose 6-phosphate. The interaction between the exogenous enzyme and cells which do not synthesize lipoprotein lipase, i.e., fibroblasts and endothelial cells, resulted in a high ratio of surface binding to degradation. In heart cell cultures and preadipocyte cultures, which produce lipoprotein lipase, the ratio of enzyme catabolized to that bound was high at all time points examined. Since in the intact organism lipoprotein lipase acts at the luminal surface of vascular endothelium, it seems expedient that these cells are able to bind the enzyme, but will catabolize it only slowly. The rapid and extensive degradation of the 125I-labeled lipoprotein lipase in heart cells and preadipocytes may be related to the metabolism of the endogenously produced lipoprotein lipase.

Cells isolated from newborn rat hearts were cultured for 10-14 days, and lipoprotein lipase activity was present in an intracellular and heparin-releasable pool. Treatment of the cultures with 10(-7) M isoproterenol for 3 min resulted in a 3-fold increase in heparin-releasable lipoprotein lipase and a concomitant decrease in residual cellular enzyme activity. Similar results were obtained by treatment with dibutyryl cAMP. Treatment with isoproterenol or dibutyryl cAMP for 2 h affected glycosylation of immunoadsorbable lipoprotein lipase, so that the ratio of [3H]galactose to [14C]mannose in the heparin-releasable enzyme increased from 3.8 (control) to 13.0 (isoproterenol-treated). The change in the ratio of the sugars in the cellular fraction of the enzyme was from 3.1 to 9.9. 2 h treatment with isoproterenol did not enhance new enzyme synthesis, as determined by incorporation of [3H]leucine into immunoadsorbable lipoprotein lipase. 24 h after addition of either isoproterenol or dibutyryl cAMP to the culture medium, stimulation of enzyme synthesis was demonstrated. The present results permit three effects of isoproterenol on lipoprotein lipase to be distinguished: stimulation of translocation from a cellular to heparin-releasable pool; enhanced processing of mannose residues and terminal glycosylation; stimulation of synthesis of enzyme protein.

Thioglycollate-elicated mouse peritoneal macrophages spontaneously secrete lipoprotein lipase during culture. Exposure of the cultures to 50 ng/ml of recombinant human tumor necrosis factor (rTNF) for 48 h resulted in a 69% reduction in lipoprotein lipase activity in the culture medium with a concomitant decrease in cellular enzyme activity. The decrease in enzyme activity was not the result of rTNF-dependent reduction in the total protein synthesis, since the presence of rTNF did not affect [3H]leucine incorporation into cellular proteins. The effect of rTNF on lipoprotein lipase was reversible; upon TNF withdrawal, enzyme activity returned to basal levels after 60 h. The reduction of lipoprotein lipase in rTNF-treated cultures could be completely prevented by preincubation with a specific antiserum against recombinant human TNF. The late onset of decrease of lipoprotein lipase (LPL) activity suggests that rTNF might induce a mediator, which in turn suppresses LPL production. While rTNF was very effective in reducing lipoprotein lipase activity in mouse peritoneal macrophages, it did not affect lipoprotein lipase activity when added to the murine J774 cell line and to CT2 macrophage-like cells, a variant of the J774 cell line.

The sand rat (Psammomys obesus) is a desert rodent in which obesity and diabetes mellitus appeared only subsequent to feeding laboratory animal chow. To study the role of lipoprotein lipase in the development and maintenance of obesity in the sand rat, enzyme activity in various organs and in plasma of sand rats or albino rats was determined following a 20-hour fast, or 16 hours after injection of cholera toxin. Despite comparable change in body weight, an altered pattern of enzyme distribution and regulation was observed in the sand rat. Neither fasting nor cholera toxin had an effect on heart and daiphragm muscle lipoprotein lipase activity of the sand rat, but caused a 1.5- to 2-fold increase in the treated albino rats. By using an isolated perfused heart system, we were able to measure enzyme activity present in the heparin-releasable fraction that represents the functional pool of the enzyme. In both species, the heparin-releasable fraction of the heart increased twofold following fasting, though initial values were lower in sand rat. In both species, fasting and cholera toxin administration resulted in an increase in plasma and liver lipoprotein lipase activity. Adipose tissue lipoprotein lipase activity of sand rat, unlike the albino rats, was similar in the various fat regions and was not lowered by food deprivation or cholera toxin administration. After both treatments, sand rat plasma insulin levels exceeded fivefold those of albino rats. Adipose tissue lipoprotein lipase activity of fed and fasted normal and diabetic sand rats correlated negatively with plasma insulin and glucose levels.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of phosphatidylinositol-specific phospholipase C (PI-PLC) on the release of lipoprotein lipase was studied in F 1 heart cell cultures. Exposure of the cultures for 10 min to PI-PLC resulted in a 2-fold increase in the release of lipoprotein lipase (LPL) into the culture medium. PI-PLC released LPL from the heparin-releasable pool and PI-PLC was not effective in cultures pretreated with heparin. Insulin had no influence on the release of LPL from the heart cell cultures, even though it enhanced the uptake of 2-deoxy[ 3 H]glucose by these cells. In cultures labeled with 35 S, treatment with PI-PLC resulted in an increase in the release of 35 S-labeled proteoglycan. PI-PLC was also effective in enhancing the release of bovine LPL exogenously bound to cultured aortic smooth muscle cells. The findings that PI-PLC was not effective after heparin, that it did release exogenously added LPL to cell cultures and that it released 35 S-labeled proteoglycan, were interpreted to indicate that PI-PLC apparently acts on the release of LPL in an indirect manner, releasing heparan sulphate to which LPL is bound. As there is a previously described correlation between circulating LPL and the heparin-releasable LPL, we hypothesize that the activity of PI-PLC in the endothelial cell membrane or plasma phosphatidyl-specific phospholipase D regulates the plasma LPL levels.

Rat hearts were perfused with heparin for 2 min at 4°C. The lipoprotein lipase activity in the perfusate was inhibited by antiserum to rat adipose tissue lipoprotein lipase. By immunoblotting, the lipoprotein lipase derived from the functional pool of the heart was found to be a protein with an apparent M r of 69000. After incubation of the perfusate at 37°C for 24 h an immunologically reactive protein with an apparent M r of 28000 was found. This protein is not a physiological derivative of the enzyme but a degradation product.

• In a retrospective survey of drug-induced hepatitis during a ten-year period, we found that quinidine sulfate was the most common offending agent. We analyzed the clinical and laboratory data of the 33 cases of quinidine-induced hepatitis and noted the following: (1) It is an easily recognized drug reaction, because, in most patients, fever preceded liver damage. (2) The clinical picture usually includes fever and sometimes is accompanied by gastrointestinal symptoms, rash, and thrombocytopenia, which resolved after discontinuation of drug therapy, but reappeared promptly after a rechallenge. (These features suggest a hypersensitivity mechanism.) (3) The histologic findings of the liver biopsy specimens consisted of portal and parenchymal, acute and chronic hepatitis, combined with granulomas. (4) In a long-term follow-up study of 15 patients, no liver function abnormalities were found. We thus conclude that quinidine-induced hepatitis, when recognized early, is a reversible drug reaction. (Arch Intern Med1986;146:526-528)

Acenocoumarol sensitivity index (ASI) was calculated in 36 patients receiving amiodarone and acenocoumarol concomitantly, by dividing the acenocoumarol daily dose (micrograms kg-1 day-1) by the prothrombin ratio expressed as International Normalised Ratio (INR). It was found to be significantly lower (4.2 +/- 0.3 micrograms kg-1 day-1) than the ASI (11 +/- 0.6 micrograms kg-1 day-1) determined in 35 patients in the control group, who received acenocoumarol and not amiodarone. In 15 patients, ASI was 13.2 +/- 1.4 and 4.2 +/- 0.6 micrograms kg-1 day-1 before and after initiation of amiodarone therapy, respectively. In 5 patients, ASI was 6.2 +/- 0.6 micrograms kg-1 day-1, while patients were receiving both medications, and 28.1 +/- 6.1 micrograms kg-1 day-1 following discontinuation of amiodarone therapy. ASI determined while patients were on both medications was not affected by the presence of mild impaired renal or liver function. In 7 patients treated with both drugs concomitantly, severe bleeding diathesis developed. It is concluded that amiodarone augmented the anticoagulant effect of acenocoumarol in all patients receiving both drugs. An initial reduction of acenocoumarol daily dose by 50% and further adjustment of acenocoumarol dose according to daily prothrombin ratio is recommended. It is also suggested that acenocoumarol dose should be adjusted after cessation of amiodarone therapy.

Rat heart cell cultures were used to study uptake of chylomicron cholesteryl ester, using a nondegradable analog, cholesteryl linoleyl ether. Rat mesenteric duct chylomicrons were labeled biosynthetically with palmitate and with [ 3 H]cholesteryl linoleyl ether or [ 14 C]cholesteryl ester by transfer from high-density lipoprotein. Rat heart cell cultures incubated with chylomicrons labeled with [ 3 H]cholesteryl linolpeyl ether and [ 14 C]cholesteryl ester took up both lipids to the same extent, and the intracellular degradation of the labeled cholesteryl ester was inhibited by chloroquine. The uptake of [ 3 H]cholesteryl linoleyl ether exceeded that of 125 I-labeled chylomicron protein by an order of magnitude, indicating that these may be nonrelated phenomena. The extent of uptake of the labeled cholesteryl linoleyl ether was correlated with the activity of endogenous lipoprotein lipase of the heart cell cultures. However, the uptake of the labeled cholesteryl ether from intact chylomicrons and from chylomicron remnants, prepared by a membrane-supported lipoprotein lipase in three different systems, was the same. These findings suggest that lipoprotein lipase may play a role in cellular uptake of chylomicron cholesteryl ester independently of hydrolysis of triacylglycerol. This hypothesis was further tested and the results are presented in the accompanying paper (Friedman, G., Chajek-Shaul, T., Stein, O., Olivecrona, T. and Stein, Y. (1981) Biochim. Biophys. Acta 666, 156–164).

In this research we have studied the role of lipoprotein lipase in the uptake of cholesteryl linoleyl ether and the possible dissociation between lipolysis of triacylglycerol and cellular uptake of cholesteryl linoleyl ether. Heart cell cultures were presented with chylomicron remnants prepared by heart cell lipoprotein lipase, bacterial lipase and milk lipoprotein lipase. The uptake of the labeled cholesteryl ether from remnants prepared by milk lipoprotein lipase was significantly higher than that from native chylomicrons, and addition of milk lipoprotein lipase doubled the uptake of cholesteryl ether from remnants produced by membrane-supported lipoprotein lipase of heart cell cultures. However, remnants which had undergone complete lipolysis by either bacterial lipase or heart cell culture-associated lipoprotein lipase were not better donors of cholesteryl ether than native chylomicrons. The uptake of cholesteryl linoleyl ether by the heart cell cultures was related to the concentration of milk lipoprotein lipase up to about 1 μg protein/ml and reached a plateau between 1 and 5 μg protein/ml. In human skin fibroblasts and bovine endothelial cells, devoid of endogenous lipoprotein lipase activity, the uptake of [ 3 H]cholesteryl linoleyl ether from either chylomicrons or from labeled Intralipid was enhanced up to 100-fold by addition of milk lipoprotein lipase. A 3 day incubation of milk lipoprotein lipase at 37°C reduced markedly its ability to enhance the uptake of cholesteryl ether, even though it was able to catalyze hydrolysis of Intralipid triacylglycerol to completion. The present results indicate that a special site on the lipoprotein lipase might be involved in the facilitation of cellular uptake of cholesteryl ester. This putative role of lipoprotein lipase in the uptake of cholesteryl ester could contribute to the atherogenic potential of dietary chylomicrons, as has been proposed by the Zilversmit hypothesis.

Lipoprotein lipase synthesized by cultured rat preadipocytes is present in three compartments: an intracellular, a surface-related 3-min heparin-releasable, and that secreted into the culture medium. 30 min after addition of 6 μ M monensin, the lipoprotein lipase activity in the heparin-releasable compartment starts to decrease; by 4 h of monensin treatment the lipoprotein lipase activity in the heparin-releasable pool and in the culture medium is about 10% of that found in control dishes. The intracellular activity, which had been identified as lipoprotein lipase by an antiserum to lipoprotein lipase, increases slowly and doubles by 24 h. However, since the cellular compartment accounts for 10–25% of total activity, this increase does not account for the missing enzyme activity. To determine whether this enzyme molecule is synthesized but is not active, incorporation of labeled leucine, mannose and galactose into immunoadsorbable lipoprotein lipase was studied in control, monensin- or tunicamycin-treated cells. Addition of tunicamycin (5 μg/ml) for 24 h caused a 30–50% reduction in immunoadsorbable lipoprotein lipase, but the enzyme activity was reduced by 90%. On the other hand, 4 h monensin treatment reduced both incorporation of [3H]leucine into immunoadsorbable lipoprotein lipase and heparin-releasable and medium lipoprotein lipase activity by 57 to 77%. The immunoadsorbable lipoprotein lipase in the intracellular compartment has a [14C]mannose to [3H]galactose ratio of 0.15 and this ratio increased 6-fold in monensin-treated cells. The intracellular lipoprotein lipase in monensin-treated cells had the same affinity for both the native and synthetic substrate as the lipoprotein lipase in control cells, yet its spontaneous secretion into the culture medium and its release by 3 min heparin treatment was markedly decreased. The present results indicate that: (a) the presence of asparagine-linked oligosaccharide (formation of which is inhibited by tunicamycin) is mandatory for the expression of lipoprotein lipase activity; (b) lipoprotein lipase is active also in a high mannose form; and (c) terminal glycosylation and oligosaccharide processing, which is inhibited by monensin, may be important for the appearance of heparin-releasable lipoprotein lipase and secretion of lipoprotein lipase into the medium.

While attempting to optimize conditions for synthesis of lipoprotein lipase by cultured heart cells, we encountered an unexpected rise in enzyme activity when media were supplemented inadvertently with 100 mM Hepes buffer (4-(2-hydroxyethyl)-1-piperazineethanesulphonic acid). This finding was further investigated and optimal results were obtained at pH 7.0-7.2. The increase in lipoprotein lipase activity was time dependent; after 3-6 h there was a rise in medium activity but cellular activity increased only after 24 h. The increased enzyme activity was defined as lipoprotein lipase by inhibition with antiserum to rat adipose tissue lipoprotein lipase. A 72-h exposure to Hepes resulted in a 30% increase in the incorporation of [35S]methionine into cellular proteins and a 2-fold increase into heparin-releasable proteins. Using heparin Sepharose chromatography and stepwise elution, a lipoprotein lipase enriched fraction was recovered with 2 M NaCl. The amount of [35S]methionine and [3H]galactose incorporated into protein of this fraction derived from Hepes-treated cells was 2-6-fold that of controls. A 4-fold increase in cellular lipoprotein lipase mass in Hepes-treated cells was shown by immunoblotting. Results obtained with Hepes-conditioned medium suggest the presence of cell-derived compounds that enhance release and subsequent synthesis of lipoprotein lipase. The effect of Hepes-conditioned medium on lipoprotein lipase resembled to some extent that of the addition of heparin. Therefore, it appears that when Hepes is first added to the culture medium, it might promote a release of heparan sulfate or related compounds, possibly by virtue of its negatively charged sulfonic acid residue. The accumulated heparan sulfate could then promote a sustained release of lipoprotein lipase into the culture medium which in turn leads to increased enzyme synthesis.

We have compared the effects of cellular cyclic AMP modulation on the regulation of lipoprotein lipase in cultures of rat epididymal pad preadipocytes and mesenchymal heart cells. Addition of dibutyryl cyclic AMP (dibutyryl cAMP) or 3-isobutyl-1-methylxanthine (IBMX) to preadipocytes grown in serum-containing culture medium resulted in a progressive decrease in lipoprotein lipase activity released into the culture medium so that at 6-8 h enzyme activity ranged between 20 and 30% of that recovered in the control dishes. Similar short-term (6-8 h) studies of the heart cell cultures showed a variable and much less pronounced depression of lipoprotein lipase activity. Thus, following dibutyryl cAMP and IBMX treatment, lipoprotein lipase activity ranged between 70 and 95% of control values. Incubation for 6 h with cholera toxin was followed by a 4-fold rise in the concentration of cellular cyclic AMP in both types of culture, but while in heart cell cultures enzyme activity was unchanged, lipoprotein lipase activity in preadipocytes decreased to 30% of control value. After 24 h incubation with all three effectors, an increase in lipoprotein lipase activity was seen. In the preadipocytes the increase ranged between 50 and 150% above control value, in the heart cell cultures it was 100-250%. 24-h incubation of heart cell cultures with dibutyryl cAMP resulted in a 6-fold increase of heparin-releasable lipoprotein lipase activity while residual activity was doubled. The rise in surface-bound lipoprotein lipase was evidenced also by an increase in the lipolysis of chylomicron triacylglycerol. In the presence of cycloheximide, the dibutyryl cAMP-induced heparin-releasable and residual lipoprotein lipase activity declined at the same rate as the basal activity. The reason for the difference in response of cultured preadipocytes and heart cells to the effectors during the first 8 h of incubation has not been elucidated, but could be related to a possible absence of hormone-sensitive lipase in the heart cells, and hence in a difference in intracellular metabolism of triacylglycerol. On the other hand, a common mechanism can be postulated for the long-term effect of cyclic AMP on the induction of lipoprotein lipase activity in both types of cultures. It probably involves mRNA and protein synthesis, which culminates in an increase in enzyme activity.

Cells isolated from newborn rat hearts were cultured in the presence of 100 mM Hepes (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid). Lipoprotein lipase activity was present in an intracellular and heparin-releasable pool and was also secreted into the culture medium. Treatment of the cultures with 5 μg/ml tunicamycin caused almost complete loss of lipoprotein lipase activity in all three compartments. In control cultures, immunoblotting of lipoprotein lipase derived from all three pools revealed a single band of lipoprotein lipase with an apparent Mr of 56000. In the tunicamycin-treated cultures, the enzyme appeared only intracellularly and had an apparent Mr of 49000. No immunoreactive enzyme was found in the medium. Thus, glycosylation of lipoprotein lipase in heart cell cultures is mandatory for enzyme activity and translocation from an intracellular to the heparin-releasable pool and for secretion into the medium.

Lipoprotein lipase (LPL), the key enzyme in the catabolism of chylomicron and very low-density lipoprotein (YLDL) triacylglycerol is present in the heart in two compartments, one intracellular, the other situated on the cell surface [1]. The surface compartment has been localized to the plasma membrane of endothelial cells, and it is also the site of action of the enzyme. LPL in the rat heart is delivered to its site of action by a vesicular transport, which can be inhibited by colchicine [2]. The cellular origin of the enzyme, whether it is synthesized in the myocardial muscle cells, or in the mesenchymal cells of the interstitium, which comprises the capillary endothelium, pericytes and fibroblasts, has been disputed. It has been shown that cultured cells derived from newly born rat heart [3] are capable of synthesizing LPL [4]. With the help of microscopy and cytochemistry it has been established that such cultures contain two types of cells, one which represents the cardiac myocytes (M), the other which comprises the mesenchymal cells (F). It has become possible to differentiate between the two cell types with the help of “preplating” [5] and to obtain cultures with a preponderance of one cell type.

Exposure of rat heart cell cultures, consisting mainly of nonbeating mesenchymal cells, to 50 ng/ml of bacterial lipopolysaccharide (LPS) for 24 h resulted in a more than 80% reduction in lipoprotein lipase activity. The loss of enzymic activity was accompanied by a concomitant reduction in enzyme protein, as shown by immunoblotting. Addition of LPS to the culture medium resulted also in the production of tumor necrosis factor (TNF), and the fall in lipoprotein lipase in LPS-treated cultures could be prevented by an antibody to TNF. Addition of recombinant human TNF to the heart cell cultures also depressed lipoprotein lipase activity. LPS treatment of preadipocytes in culture resulted in a fall in lipoprotein lipase activity and TNF production. Since TNF is known as a macrophage product, the cultures were tested for phagocytic capacity, and only 0.2-1.3% of the cells were shown to engulf Staphylococcus albus. Immunofluorescent staining with monoclonal antibodies OX-1, which identify leukocyte common antigen, was negative, and only 0.1 +/- 0.07% of the cells were positive after staining with OX-42 antibody to iC3b receptor. Both antibodies stained more than 98% of rat peritoneal macrophages used as controls. Since LPS treatment of macrophages at numbers comparable to or exceeding the number of phagocytic cells present in the heart cell cultures did not induce measurable amounts of TNF, it is suggested that in the heart cell cultures, TNF may be produced by cells other than macrophages.

Rats were injected intravenously with cholera toxin, a potent stimulator of adenylate cyclase, and lipoprotein lipase was determined in various organs and plasma. 16 h after cholera toxin injection, lipoprotein lipase activity increased 2–6-fold in heart, diaphragm and lung and decreased to one-third in adipose tissue. An increase in lipoprotein lipase activity was seen in the plasma and in the liver, as determined by antiserum to lipoprotein lipase. The increase in heart lipoprotein lipase was preceded by a rise in cyclic AMP and continued for 24 h when cyclic AMP returned to base-line levels. Both heparin-releasable and residual lipoprotein lipase increased in the heart, but to an unequal extent. The more pronounced rise in residual activity (up to 10-fold) could have contributed to an increase in the t 1 2 of heart lipoprotein lipase from 1.5 to 2.6 h. The relatively lower increase in heparin-releasable lipoprotein lipase could have been due to a loss of the enzyme from this compartment into the circulation. The effect of cholera toxin on heart and adipose tissue lipoprotien lipase was observed in fasted, fed and super-fed animals and thus appears to be independent of the nutritional state of the animal. Since cholera toxin not only mimics hormonal stimulation, but causes an exaggerated response to hormones, it made studies on some aspects of regulation of both the functional and storage forms of lipoprotein lipase in the intact organism possible.

When isolated rat livers were perfused with medium containing lipoprotein lipase, 40–60% was taken up during a single passage. This value was similar for lipoprotein lipase derived from culture medium of rat preadipocytes, and for lipoprotein lipase purified from bovine milk. It was also, similar, irrespective of the lipoprotein lipase concentration, at least up to 1 μg/ml. Immediately following its uptake by the liver, a large fraction of the lipoprotein lipase could be released by heparin, but the magnitude of this fraction decreased with time. The enzyme lost its catalytic activity rather rapidly, but its degradation to acid-soluble products, or to larger fragments, was much slower. On heparin-agarose chromatography, the enzyme taken up by the liver eluted at a lower salt concentration than the original lipoprotein lipase preparation. This change in affinity for heparin suggests that the originally dimeric lipoprotein lipase had dissociated into monomers, in analogy to the findings in model experiments. It is suggested that the initial uptake of lipoprotein lipase occurs by binding to a polyanion at the liver cell surface. This is followed by endocytosis and dissociation of the enzyme from its heparan sulfate-like binding site. Acidification of the endosome may cause a conformational change in the lipase molecule with dissociation to inactive monomers, preceding ultimate proteolytic degradation.

4 h after intravenous injection of recombinant HuTNF-alpha to fed rats, an increase in heart, diaphragm, and plasma lipoprotein lipase activity was observed. At the same time, a 40-60% decrease in enzymic activity in epididymal fat pad and kidney and 40% decrease in hepatic lipase activity in liver had occurred. Similar results were obtained 20 h after injection of recombinant HuTNF-alpha into fasted rats. Pretreatment with Indomethacin did not affect the changes in tissue lipoprotein lipase activity observed following recombinant HuTNF-alpha administration. Serum triacylglycerol concentration increased by 2- and 6-fold; 4 and 20 h after recombinant HuTNF-alpha administration. Disappearance of 14C-labeled triacylglycerol from the circulation after injection of small chylomicrons, biosynthetically labeled in their triacylglycerol and cholesterol moieties, was lower in TNF-treated than in control rats. However, the clearance rate of triacylglycerol was the same or even higher in recombinant HuTNF-alpha treated rats (assuming that 14C-labeled chylomicron triacylglycerol represents the serum triacylglycerol pool). The livers of recombinant HuTNF-alpha-treated rats and controls contained similar amounts of 14C-labeled lipids, but less [3H]cholesterol, suggesting that in recombinant HuTNF-alpha-treated rats, the liver took up chylomicron remnant particles enriched with triacylglycerol. Separation of the d less than 1.04 g/ml fraction of serum obtained from control and recombinant HuTNF-alpha treated rats by zonal ultracentrifugation revealed that in recombinant HuTNF-alpha-treated rats the lipoprotein particles were less lipolyzed than in controls. The secretion rate of [3H]triacylglycerol into the serum was determined 90 min after injection of [3H]palmitate albumin complex and Triton WR 1339. In recombinant HuTNF-alpha-treated rats, the secretion of [3H]triacylglycerol into plasma was 48% higher than in controls. It is suggested that the increase in lipoprotein lipase activity of heart and diaphragm resulted from an indirect effect of TNF. It is concluded that the increase in serum triacylglycerol in the recombinant HuTNF-alpha-treated rats is due mainly to an increased secretion of triacylglycerol by the liver. Impaired lipolysis, probably due to a fall in hepatic lipase could also contribute to the rise in plasma triacylglycerol.

Three macrophage cell lines, J774(2), CT2 and J7H1 were compared with respect to synthesis and secretion of lipoprotein lipase. The enzyme activity measured was characterized as lipoprotein lipase on the basis of serum dependence and inhibition by 1 M NaCl. Enzyme activity in all three lines increased with time in culture and the highest activity was found in the medium of the CT2 line which is adenylate cyclase deficient while that in the J7H1 line, cyclic AMP-dependent protein kinase deficient, was intermediate. The half life of the enzyme activity in conditioned medium from all three lines was 30-40 min, suggesting that the different levels of activity observed do represent different levels of enzyme production by the cells. About 80% of the lipoprotein lipase activity from all three lines was present in the medium and 50-70% of cellular activity could be released into the medium by a 3-min exposure to heparin. In addition, 24 h incubation with heparin enhanced enzyme secretion in all three lines. To determine the role of cyclic AMP in the regulation of lipoprotein lipase activity use was made of dibutyryl cAMP, methyl isobutylxanthine (IBMX) and cholera toxin. These agents strikingly depressed lipoprotein lipase activity in the J774(2) line but only dibutyryl cAMP was active in the CT2 line (adenylate cyclase deficient). In the J7H1 (protein kinase deficient) line there was no response to dibutyryl cAMP or IBMX over the first 4 h of incubation. Addition of these agents did not affect total cell protein synthesis. The present findings indicate that in the intact cells changes in cyclic AMP levels are associated with a change in the activity of lipoprotein lipase.

Four cell types, F1 rat heart cells, rat preadipocytes, human skin fibroblasts and bovine endothelial cells, were used to investigate whether surface binding of lipoprotein lipase was essential in the transmembrane transport of chylomicron cholesteryl ester. Exposure of F1 heart cells to colchicine resulted in decrease in endogenous surface-bound lipoprotein lipase and a concomitant fall in the uptake of chylomicron cholesteryl linoleyi ether, a nondegradable analog of cholesteryl ester. Uptake of chylomicron cholesteryl linoleyi ether was enhanced by addition of milk lipoprotein lipase and this enhancement also persisted in the presence of colchicine. The drug did not reduce surface binding of the enzyme. Milk lipoprotein lipase was bound to the cell surface of the different cell types and its fate during chase in enzyme-free medium was determined. The t 1 2 of surface-bound enzyme in endothelial cells and in F1 heart cells was about 2h; it was 4 h in skin fibroblasts. The decrease in surface-bound lipoprotein lipase was accompanied by a parallel fall in the binding and uptake of chylomicron cholesteryl linoleyi ether by the various cell types examined. This decrease in the uptake of cholesteryl linoleyl ether occurred even though lipoprotein lipase activity in the medium was present, as evidenced by the hydrolysis of [14C]triacylglycerol. Release of surface-bound endogenous or exogenous lipoprotein lipase by heparin was accompanied by almost complete elimination of uptake of cholesteryl linoleyl ether in presence of complete hydrolysis of [14C]triacylglycerol. The present results indicate that the transmembrane transport of cholesteryl ester is catalyzed by lipoprotein lipase only when the enzyme is bound to the cell membrane.

The study was undertaken to investigate the met- abolic fate of post-lipolysis mesenteric lymph small chylomi- crons produced in vitro. Small chylomicrons doubly labeled with (gH)cholesterol (more than 70% in cholesteryl esters) and ('4C)palmitate-labeled triglycerides were collected from rat mesenteric lymph during periods of fasting. Lipolysis was per- formed in vitro with lipoprotein lipase purified from bovine milk. More than 98% of the chylomicron-triglycerides could be hydrolyzed to fatty acids. Post-lipolysis chylomicrons were separated by zonal ultracentrifugation, characterized, and tested for biological behavior in intact rats. Following lipolysis the lipoproteins lost nearly all their triglycerides, apoA-I, and apoC, and were relatively enriched with cholesteryl esters, unesterified cholesterol, phospholipids, and apoB. Three prep- arations were tested for biological behavior: pooled (total) post-lipolysis chylomicrons (diameter -250 A); particles at the ascending part of the zonal effluent (diameter -300 A), and at the descending part (diameter -200 A). After intravenous injection to intact rats, ('H)cholesteryl ester decay was very rapid with pooled lipoproteins and the 300-A preparation (tlIP = 5-10 min). The 200-A preparation in contrast stayed in circulation much longer (t1/2 = 60-90 min).l The study thus demonstrated metabolic heterogeneity of post-lipolysis small chylomicrons and indicated that some may form an LDL- like subpopulation with a plasma lifetime slower than "rem- nants" but faster than LDL.-Chajek-Shaul, T., S. Eiaenberg, Y. Oschry, and T. Olivecrona. Metabolic heterogeneity of post-lipolysis rat mesenteric lymph small chylomicrons pro- duced in vitro. J. Lipid Res. 1983. 24: 831-840.

• We analyzed the clinical course of 65 adult patients hospitalized because of measles during the years 1975 and 1981-1982. Liver involvement was found in 80% (52/65) of the patients, five patients had clinical jaundice. The disturbances of liver function tests reached their peak values between days 5 and 10 of the disease. In this study of measles in adulthood we have three observations of unusual interest: (1) hepatitis occurs commonly in the more severely ill patients and it may manifest clinically as jaundice; (2) long-term follow-up (up to seven years) shows a clear tendency to complete resolution of the liver damage; (3) there is a clear correlation between the severity of hepatic involvement and the occurrence of secondary bacterial infections. (Arch Intern Med1983;143:674-677)