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PubMed1991

An improved method for removal of antithrombin III from post-heparin plasma lipase fractions with a high recovery rate.

Affinity chromatography on heparin-Sepharose has been widely used for the purification of post-heparin plasma triglyceride lipases, but this procedure alone yields lipase fractions with a high content of antithrombin III (AT), which also binds to heparin and coelutes with the lipases. A rapid procedure in which this major contaminant is reduced by the use of affinity chromatography on heparin-Sepharose with low affinity for AT and further removal by anti-AT IgG Affi-Gel 10 column chromatography is reported and the results are compared with these of the conventional heparin-Sepharose and Concanavalin A-Sepharose column chromatography two step method. While the AT contamination of hepatic lipase eluate from conventional heparin-Sepharose column chromatography was 92 mg/dl in 100 mg/dl protein, heparin-Sepharose with low affinity for AT yielded samples with 55 mg/dl in 100 mg/dl protein. A second passage on concanavalin A-Sepharose of the sample from conventional heparin-Sepharose reduced the AT content from 92 mg/dl to 42 mg/dl in 100 mg/dl protein, but passage of the sample from heparin-Sepharose with low affinity for AT through an anti-AT IgG Affi-Gel 10 column removed almost all of the AT contamination from the lipase sample. This hepatic triglyceride lipase (HTGL) sample had a specific activity 1,963-fold higher than that of post-heparin plasma with a yield of 17% of the starting material, showing an excellent recovery rate compared with similar methods in use.

Antithrombin III↗

PubMed1976

Restoration of a regulatory response to low density lipoprotein in acid lipase-deficient human fibroblasts.

Previous studies have shown that cultured fibroblasts derived from patients with genetic defects in lysosomal acid lipase (i. e. the Wolman Syndrome and Cholesteryl Ester Storage Disease) are defective in their ability to hydrolyze the cholesteryl esters contained in plasma low density lipoprotein (LDL). As a result, these mutant cells show a reduced responsiveness to the regulatory actions of LDL, as evidenced by a decreased LDL-mediated suppression of the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase and by a decreased LDL-mediated activation of cellular cholesteryl ester formation. In the current studies, the Wolman Syndrome and Cholesteryl Ester Storage Disease cells were grown in the same Petri dish with mutant fibroblasts derived from a patient with the homozygous form of Familial Hypercholesterolemia. Whereas pure monolayers of either the Familial Hypercholesterolemia cells (lacking cell surface LDL receptors) or the acid lipase-deficient cells (lacking cholesteryl ester hydrolase activity) responded poorly to LDL, the mixed monolayers developed lipoprotein responsiveness as measured by an enhancement of both LDL-mediated suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and LDL-mediated stimulation of cholesteryl ester formation. This effect was shown to result from the release of the lysosomal acid lipase from the Familial Hypercholesterolemia homozygote cells into the culture medium and its subsequent uptake by the acid lipase-deficient cells. The acquisition of this acid lipase activity enhanced the ability of the Wolman Syndrome and Cholesteryl Ester Storage Disease cells to respond to the lipoprotein by suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase and activation of cellular cholesteryl ester formation. These data emphasize the importance of the lysosomal acid lipase in the cellular metabolism of LDL cholesteryl esters and, in addition, demonstrate that delivery of this enzyme to genetically deficient cells can enhance the regulatory response to the lipoprotein.

Binding Sites↗

PubMed1990

[Semiquantitative lipase determination--a useful screening test for pancreatitis?].

In 233 sera, taken from 112 patients and 20 healthy blood-donors, we have compared RapiTex-Lipase, a semi quantitative immunochemical latex test for the determination of the lipase, with the conventional quantitative method of determination in order to establish its diagnostical value as a screening test for acute pancreatitis. It appeared that, with a positive result of the test increased values of lipase were found in 98% of the cases, but that a negative result of the test did not exclude an increased lipase. The sensitivity of the test as to the quantitative determination of the lipase depended directly on the activity of the lipase and turned out to be acceptable at 88% only with values 4 X higher than the upper limit of the normal range. With values 5 X higher and more, it reached 100%. Even if the test, due to its very high level of discrimination, did not show a reaction in every case of unspecific extrapancreatic hyperlipasemia, its organ-specificity for the pancreas was reduced and came to 80 to 96% in patients with renal insufficiency, diseases of the liver, abuse of alcohol and in various non-pancreatic intra- or extra-abdominal affections. In 16/18 patients with acute pancreatitis the test used for screening turned out positive (sensitivity 89%), two patients with values between 2 and 4 X the upper limit of the norm had a negative test.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute Disease↗

PubMed1979

Modification of the substrate specificity of rat hepatic lipase by collagenase treatment.

Collagenase is currently used in the isolation of rat hepatocytes, but it rapidly inactivates the heparin-releasable triacylglycerol lipase of the liver. Since collagenase-isolated liver cells contain a heparin-releasable monoacylglycerol hydrolase, a study was made on the effect of collagenase treatment on the substrate specificity of purified heparin-releasable lipase of rat liver. Incubation of the purified lipase with collagenase selectively decreased the triacylglycerol lipase activity of the enzyme with no effect on the monoacylglycerol hydrolase activity. Gel filtration of the lipase before and after collagenase treatment indicated cleavage of a small molecular weight fragment from the enzyme. This resulted in a preparation with less triacylglycerol lipase activity but still capable of monoacylglycerol hydrolysis.

Animals↗

PubMed1989

[Extrapancreatic hyperamylasemia. Diagnostic value of isoamylase and lipase determination].

The P- and S-isoamylase and lipase of 72 patients with extrapancreatic hyperamylasemia were determined and their diagnostic value checked to rule out a pancreatic origin. The hyperenzymemia was generally slight although extremely high values were observed in isolated cases. The increased serum amylase results were more often caused by P-, rather than S-isoamylase, while in 28% of cases lipase was also increased. In lung diseases, anorexia and disorders of the head organs only S-isoamylase was pathologically increased while P-isoamylase and lipase remained normal. In other entities such as liver, stomach and intestinal diseases, functional disorders, acidosis, infections, etc., the isoenzymes and lipase showed a variable tendency to increase. Thus, extrapancreatic hyperamylasemia could not always be identified by detection of isoamylases or with the aid of lipase determinations. Overall, however, lipase more often remained in the normal range and was therefore more useful than determination of the isoamylases in differentiating hyperenzymemia.

Acidosis↗

PubMed1989

Circulating concentrations of trypsin-like immunoreactivity and activities of lipase and amylase after pancreatic duct ligation in dogs.

The possibility that assay of circulating trypsin-like immunoreactivity (TLI) could assist in the diagnosis of acute pancreatitis in dogs has been examined by assaying plasma TLI concentrations after pancreatic duct ligation and comparing the results with plasma activities of lipase and amylase. Venous blood samples were obtained from 8 dogs before surgery, then daily for 5 days and at 14 days after ligation of pancreatic ducts. Plasma concentrations of TLI increased within 24 hours and tended to peak before and to decrease more rapidly than activities of lipase and amylase, remaining greater than the control range for 5 days in all but 2 dogs. Plasma lipase and amylase activities increased together and remained greater than the control range in all dogs for 5 days after surgery. Regression analysis of all postoperative data indicated significant correlations between concentration of TLI and lipase activity (r = 0.67, P less than 0.001), concentration of TLI and amylase activity (r = 0.53, P less than 0.001), and between lipase and amylase activities (r = 0.74, P less than 0.001). These findings suggested that assay of TLI may provide an early indication of acute pancreatitis in dogs. Because TLI is specifically pancreatic in origin, high plasma TLI concentration may prove a more reliable indicator of clinical pancreatitis than high activities of amylase or lipase, which may be derived from extrapancreatic tissues.

Amylases↗

PubMed1988

Fractional urinary clearance of immunoreactive lipase in chronic pancreatic disease.

Using an immunoenzymatic method, we studied lipase in the serum and urine of 23 controls, 22 chronic pancreatitis patients in symptomatic remission, and in 9 patients with proven pancreatic cancer. Serum and urine lipase and its fractional urinary clearance were compared with those of amylase and immunoreactive trypsin. Lipase immunoreactivity was detectable in the urine of 81.5% of the studied subjects (controls: 82%, chronic pancreatitis: 86%, pancreatic cancer: 66%); its output was higher than the upper limit of controls in 31.8% of chronic pancreatitis and in only 1 of pancreatic cancer, and it was significantly correlated with the urinary output of trypsin (r = 0.487, P less than 0.001), but not with that of amylase. A significant correlation was found between urinary output and serum levels for lipase, but not for trypsin or amylase. Fractional clearance of lipase was of the same magnitude as that of trypsin but only 0.1% that of amylase. 19% of chronic pancreatitis and pancreatic cancer showed a fractional clearance of lipase above the upper limit of controls, compared with 45% for trypsin and 3.2% for amylase. No difference in urinary clearance of the three enzymes was found between chronic pancreatitis and pancreatic cancer. In conclusion, although of no diagnostic relevance in pain-free patients with chronic pancreatic disease, this measurement can provide information on the mechanisms of renal excretion of pancreatic enzymes.

Adult↗

PubMed1988

[Acid lipases and acid cholesterol esterases: Wolman's disease and cholesteryl ester storage disease].

In the first part of the review are reported the properties of mammalian acid lipases and cholesterol esterases. Lysosomal acid lipase differs from the other acid or neutral lipases by its subcellular localization and a large substrate specificity on natural lipids, triglycerides and cholesteryl esters and on semi-synthetic or synthetic coloured or fluorescent substrates; the enzymatic activity of acid lipase depends on the presence of detergents and phospholipids and the structural properties are well known. In vivo, lysosomal acid lipase hydrolyses neutral lipids from exogenous origin (lipoprotein). The second part is an updated review on the diseases caused by hereditary acid lipase deficiency: Wolman's disease occurring in the first months of life and fatal before the age of one year and Cholesteryl Ester Storage Disease, a more benign form with normal lifespan. Both diseases are characterized by massive storage of neutral lipids. Molecular and metabolic pathways, new diagnostic tools used for the diagnosis and experimental cellular model systems are reviewed and discussed.

Carboxylic Ester Hydrolases↗

PubMed1988

Human gastric lipase: a sulfhydryl enzyme.

One sulfhydryl group was modified per mol of native human gastric lipase after incubation at pH 8.0 with 5,5'-dithiobis(2-nitrobenzoic acid) for 18 h or with 4,4'-dithiopyridine for 100 min. With both reagents a direct correlation was found between the modification of one sulfhydryl group and the loss of human gastric lipase activity. Incubation of human gastric lipase with a new hydrophobic sulfhydryl reagent dodecyldithio-5-(2-nitrobenzoic acid) in 30-fold molar excess, at pH 3.0, 5.0, and 8.0, induced immediate and complete human gastric lipase inactivation. Unlike 5,5'-dithiobis(2-nitrobenzoic acid) and 4,4'-dithiopyridine, dodecyldithio-5-(2-nitrobenzoic acid) almost instantaneously stopped the course of tributyrin hydrolysis by human gastric lipase. Human gastric lipase can thus be said to be a sulfhydryl enzyme.

Algorithms↗

PubMed1986

Hepatic triacylglycerol lipase in circulating blood of normal and tumor-bearing mice and its hydrolysis of very-low-density lipoprotein and synthetic acylglycerols.

A large amount of triacylglycerol lipase activity was present in the circulating blood of normal mice, and this activity decreased with development of Sarcoma 180 inoculated intraperitoneally. Triacylglycerol lipase in plasma of both normal and tumor-bearing mice was retained on the heparin-Sepharose columns and over 90% of the activity was eluted with 0.75 M NaCl. This enzyme had similar properties to hepatic triacylglycerol lipase and hydrolyzed very-low-density lipoprotein (VLDL)-triacylglycerol. Hepatic triacylglycerol lipase in plasma of normal mice hydrolyzed tricaprin and trilaurin most readily and better than 1-monoacylglycerols with the same acyl chain length. The hydrolyzing activities decreased with increase in the acyl chain length. The activity toward triolein was also higher than that toward 1-monoolein. 1-Monomyristin was hydrolyzed better than trimyristin. In contrast, hepatic triacylglycerol lipase in plasma of mice on day 4 after tumor inoculation hydrolyzed 1-monoacylglycerols better than triacylglycerols with the same acyl chain length. Hydrolysis of triolein by hepatic triacylglycerol lipase in plasma of both normal and tumor-bearing mice was reduced in the presence of 1-monoacylglycerols in the reaction mixture. The orders of their inhibitory effects coincided with the orders of the hydrolyzing activities toward 1-monoacylglycerols.

Animals↗

PubMed1986

Serum immunoreactive pancreatic lipase and cationic trypsinogen for the assessment of exocrine pancreatic function in older patients with cystic fibrosis.

Indirect and qualitative tests of pancreatic function are commonly used to screen patients with cystic fibrosis for pancreatic insufficiency. In an attempt to develop a more quantitative assessment, we compared the usefulness of measuring serum pancreatic lipase using a newly developed enzyme-linked immunosorbent immunoassay with that of cationic trypsinogen using a radioimmunoassay in the assessment of exocrine pancreatic function in patients with cystic fibrosis. Previously, we have shown neither lipase nor trypsinogen to be of use in assessing pancreatic function prior to 5 years of age because the majority of patients with cystic fibrosis in early infancy have elevated serum levels regardless of pancreatic function. Therefore, we studied 77 patients with cystic fibrosis older than 5 years of age, 41 with steatorrhea and 36 without steatorrhea. In addition, 28 of 77 patients consented to undergo a quantitative pancreatic stimulation test. There was a significant difference between the steatorrheic and nonsteatorrheic patients with the steatorrheic group having lower lipase and trypsinogen values than the nonsteatorrheic group (P less than .001). Sensitivities and specificities in detecting steatorrhea were 95% and 86%, respectively, for lipase and 93% and 92%, respectively, for trypsinogen. No correlations were found between the serum levels of lipase and trypsinogen and their respective duodenal concentrations because of abnormally high serum levels of both enzymes found in some nonsteatorrheic patients. We conclude from this study that both serum lipase and trypsinogen levels accurately detect steatorrhea in patients with cystic fibrosis who are older than 5 years but are imprecise indicators of specific pancreatic exocrine function above the level needed for normal fat absorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1985

Inhibition of lipases by proteins. A kinetic study with dicaprin monolayers.

We report further investigations on protein inhibition of pancreatic and microbial lipases carried out with the monolayer technique. When beta-lactoglobulin A, melittin, serum albumin, myoglobin, and a protein inhibiting lipase from soybean were preincubated with a dicaprin film at a surface pressure of 35 dynes/cm, no activity was detected with horse pancreatic or Rhizopus delemar lipases. By contrast, Rhizopus arrhizus and Geotrichum candidum lipase activities were not impaired under the same conditions. Experiments using mixed lipid-protein film transfer clearly show that the inhibition of pancreatic lipase is due to the protein associated with lipid and not caused by direct protein-enzyme interaction in the aqueous phase. Three parameters were used to determine the surface properties of the various proteins at the dicaprin/water interface; namely, the initial rate of surface pressure increase, (delta pi/delta t)t = 0, the maximal surface pressure increase, delta pi max, and the critical surface pressure, pi c. A positive correlation was observed between values of (delta pi/delta t)t = 0 of proteins and their respective capacity to inhibit pancreatic and R. delemar lipases. By contrast, there was no apparent correlation with the two other parameters, delta pi max or pi c.

Animals↗

PubMed1985

Subcellular localization of acid lipase in rat liver.

The intracellular localization of acid lipase was examined by several subcellular fractionation techniques. Upon differential centrifugation, acid lipase was detected mainly in the lysosomal fraction. When linear sucrose density gradient centrifugation was used, the mean density of acid lipase was similar to that of lysosomal marker enzymes. After Triton-treatment of rats, however, acid lipase was recovered at a density of 1.10-1.16, which is more than that of tritosomes, when tissues were homogenized with a Potter-Elvehjem homogenizer. But by homogenizing the liver from these rats by pressing it through a stainless steel net, acid lipase was mainly recovered at the same density as that of tritosomes. These results indicate that acid lipase is localized mainly in lysosomes in rat liver.

Animals↗

PubMed1970

Activation of hormone-sensitive lipase in extracts of adipose tissue.

Rat adipose tissue was homogenized in 0.154 m KCl, and the supernatant fluid, obtained after centrifugation at 15,000 g, was extracted with benzene to remove triglycerides. Most of the lipase activity in the extracted fluid was precipitated with ammonium sulfate between 15 and 40% saturation. The specific activity of the lipase in this fraction was about three times that in the benzene-extracted supernatant fluid. The specific activity of the monoglyceride esterase was increased to a lesser extent. Lipase activity in the benzene-extracted fluid and in the ammonium sulfate fraction was increased 15-45% by incubation with 0.3 mm ATP, 10 mm MgCl(2), and 0.03 mm cyclic AMP for 10 min before assay. None of these compounds alone or in combinations of two was as effective as all three together. The specific activity of the 15-40% ammonium sulfate fraction prepared from fat cells exposed to epinephrine and glucagon was greater than that from portions of the same cell pool not exposed to hormones. In addition, the already elevated lipase activity in preparations from hormone-treated cells was not enhanced by incubation with ATP, MgCl(2), and cyclic AMP. Thus, it seems probable that the lipase activity in the ammonium sulfate fractions represents, at least in part, hormone-sensitive lipase.

Adenosine Triphosphate↗

PubMed1979

Synthesis of various kinds of esters by four microbial lipases.

Ester synthesis by microbial lipases, using homogeneous enzyme preparations, were investigated. The amount of synthesized ester was estimated by alkalimetry, and products were identified by thin-layer chromatography and infrared spectroscopy. Lipases from Aspergillus niger, Rhizopus delemar, Geotrichum candidum and Penicillium cyclopium synthesized esters from oleic acid and various primary alcohols. Only Geotrichum candidum lipase synthesized esters of secondary alcohols. Esters of tertiary alcohols, phenols or sugar alcohols were not synthesized by any lipase. Rather high concentrations of alcohol were required to synthesize the esters of ethylene glycol, propylene glycol or trimethylene glycol. Lipases from Aspergillus niger and Rhizopus delemar synthesized oleyl esters of various fatty acids and some dibasic acids. In contrast, lipases from Geotrichum candidum and Penicillium cyclopium synthesized oleyl esters only from medium or long chain fatty acids.

Aspergillus niger↗

PubMed1982

Development of pancreatic enzymes in fetal and suckling rats with emphasis on lipase and colipase.

Pancreatic amylase, chymotrypsinogen, lipase and colipase were assayed, at intervals, in rats from day 16 of fetal life until weaning. In the fetus, amylase and chymotrypsinogen accumulated regularly, in parallel, until birth. Lipase and colipase accumulation slowed down between day 20 and birth. The ratio of colipase to lipase was extremely high (9.5) and decreased until weaning towards adult values. Enzyme contents of the pancreas were depleted after birth and remained low until day 14. Intestinal concentrations were equally low, showing that pancreatic depletion was not due to hypersecretion. Protein synthesis was very active, intermediate between that of the fetus and of the adult. It is concluded that in the early suckling phase the proteins synthesized are mainly constitutive and not enzymatic. Starvation followed by refeeding showed that secretion sensitivity to nutritional stimulation only appears at 14 days. During the suckling period amylase concentrations decreased, evidencing a degree of nutritional sensitivity to the low level of carbohydrate in the diet. The productive capacity for lipase underwent a slow maturation which was not even complete at weaning, since concentrations had not yet reached adult level despite the high fat content of milk. This was in part compensated for by the high proportion of colipase but shows that lipase was not adaptative during this phase and that pancreatic lipase can hardly account for lipid digestion before weaning.

Amylases↗

PubMed1984

Proteolytic inactivation of lipase as a possible cause of the uneven results obtained with enzyme substitution in pancreatic insufficiency.

Inactivation of lipase in four commercially available pancreatin preparations in buffer solution, in duodenal juice stimulated by secretin-cholecystokinin or by Lundh test-meal, and in duodenal juice supplemented with a meat-meal homogenate, was examined during a four-hour incubation period. In the buffer solution and in the secretin-cholecystokinin-stimulated duodenal juice 64-89% of lipase activity was already lost within two hours. Trypsin activity was in inverse relation to that of lipase and soybean trypsin inhibitor. The Lundh test meal and the meat-meal homogenate significantly diminished inactivation of lipase. Substitution therapy of pancreatic insufficiency with crushed and soybean-trypsin-inhibitor supplemented preparations diminished steatorrhoea more effectively than the simple tablets. The demonstrated proteolytic inactivation of lipase indicates that pancreatic supplements have to be given in crushed or granulated form, well mixed with protein-containing meals, and that a physiological ratio of trypsin-lipase activity ought to be preserved in the preparations.

Amylases↗

PubMed1984

Lipolytic stimulation modulates the subcellular distribution of hormone-sensitive lipase in 3T3-L1 cells.

3T3-L1 cells have been a useful model system for studying adipocyte differentiation and metabolism. They acquire a hormone-sensitive lipase during differentiation (Kawamura, M., et al. 1981. Proc. Natl. Acad. Sci. USA. 78: 732-735). In the present study the control of lipolysis in these cells was investigated. Basal glycerol release from cell monolayers was 437 nmol/mg protein per hr, and could be stimulated approximately 6-fold by exposure to 1 microM isoproterenol. Subcellular fractionation of stimulated cells revealed a redistribution of triglyceride lipase activity: loss from the infranatant fraction and increase in the pellet fraction. The redistribution was dosage-dependent and reversible. Treatment of intact cells with 8-bromoadenosine 3':5' cyclic monophosphate elicited similar redistribution of the lipase activity; however, disruption and incubation of untreated cells in the presence of ATP and either cyclic AMP or the catalytic subunit from cAMP-dependent protein kinase did not. The lipase activity in the pellet fraction was increased 3- to 4-fold after maximal lipolytic stimulation of intact cells, whereas phosphorylation of the enzyme in vitro yielded 1.4- to 1.6-fold stimulation in all subcellular fractions from untreated cells. The lipase found in the particulate fraction has the same properties as the previously characterized infranatant enzyme. It is suggested that interaction of the lipase with substrate and associated intracellular membranes may be a novel feature of the regulation of lipolysis.

1-Methyl-3-isobutylxanthine↗