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PubMed1996

A novel missense mutation (Asn5-->Ile) in lecithin: cholesterol acyltransferase (LCAT) gene in a Japanese patient with LCAT deficiency.

We identified a novel missense mutation in the lecithin:cholesterol acyltransferase gene in a new case of lecithin:cholesterol acyltransferase (LCAT) deficiency. The patient was a 64-year-old diabetic Japanese male who showed an extremely low level of serum high-density lipoprotein-cholesterol, corneal opacities, anemia, and proteinuria. Both the patient's LCAT activity and mass were markedly low. DNA sequence analysis of the LCAT gene showed an A-to-T transition at base 97 in exon 1, and predicted a change in asparagine to isoleucine at the 5th amino acid of the protein. Restriction analysis of polymerase chain reaction-amplified DNA using Ase I showed that the patient was homozygous for this mutation. Our results suggested that asparagine 5 was an important amino acid and substitution with isoleucine caused marked reduction of LCAT activity and mass, resulting in LCAT deficiency.

Amino Acid Sequence↗
PubMed1989

Molecular species of phosphatidylcholine in familial lecithin-cholesterol acyltransferase deficiency: effect of enzyme supplementation.

We studied the molecular species composition of plasma phosphatidylcholine (PC) in three patients with familial deficiency of lecithin-cholesterol acyltransferase in order to determine whether certain species are increased in the absence of this enzyme activity. Compared to normal plasma, the deficient plasma contained significantly higher percentages of 16:0-18:2 and 18:0-18:2 species and lower percentages of 16:0-20:4 and 18:0-20:4 species. The bulk of the total plasma PC as well as the abnormal composition of molecular species were found in the very-low-density and low-density lipoprotein (VLDL + LDL) fractions. When the deficient plasma was incubated with partially purified enzyme from normal human plasma, there was a significant reduction in the amounts of most major species, mainly in the VLDL + LDL fraction. When the selectivity factors were calculated by dividing the percentage contribution of each species for cholesterol esterification by its percentage concentration, the highest selectivity factors were found for 16:0-18:2, 18:1-18:1 and 18:1-18:2. The order of selectivity of the enzyme for various species was very similar to that obtained earlier using normal HDL as substrate. These results show that lecithin-cholesterol acyltransferase has significant effects on the molecular species composition of plasma PC and the deficiency of the enzyme results in accumulation of certain PC species normally used by the enzyme, as well as in abnormal distribution of these species among the lipoproteins.

Adult↗
PubMed1976

Changes in the concentration of lipoprotein-X during incubation of postheparin plasma from patients with familial lecithin: cholesterol acyltransferase (LCAT) deficiency.

The concentration of lipoprotein-X (LP-X) has been studied in six patients with familial lecithin:cholesterol acyltransferase (LCAT) deficiency before and after the administration of heparin. In preheparin plasma, LP-X was present in all the patients, the concentrations ranging from 40 to 251 mg/100 ml. When postheparin plasma samples were incubated at 37 degrees C for 4 hours, LP-X could not be detected, whereas it was still present before incubation. LCAT activity was absent in the preheparin as well as in the postheparin samples. Accordingly, the changes in the concentration of LP-X could not be attributed to alterations in plasma LCAT activity. An increase in lysolecithin and a decrease in lecithin was observed during incubation of postheparin plasma samples.

Acyltransferases↗
PubMed1992

The genetic defect of the original Norwegian lecithin:cholesterol acyltransferase deficiency families.

Three of the original Norwegian lecithin:cholesterol acyltransferase (LCAT) deficiency families have been investigated for mutations in the gene for lecithin:cholesterol acyltransferase by DNA sequencing of the exons amplified by the polymerase chain reaction. A single T----A transversion in codon 252 in exon 6 converting Met(ATG) to Lys(AAG) was observed in all homozygotes. In spite of the identical mutation, the disease phenotypes differed in severity. This was not reflected in the expression of LCAT in the heterozygotes.

Female↗
PubMed1982

Promotion of sterol efflux and net transport by apolipoprotein E in lecithin:cholesterol acyltransferase deficiency.

In the plasma of 4 subjects homozygous for deficiency of lecithin:cholesterol acyltransferase, the level of many apolipoproteins (apo A-I, apo A-II, apo B, apo D) was greatly relative to normal, while that of apo E is increased 5-fold. The lipoprotein complex containing lecithin:cholesterol acyltransferase with apo A-I and apo D in normal plasma is completely absent. The major part of apo E is unassociated with other apolipoproteins. The apoprotein-dependence of sterol efflux and net transport from human skin fibroblasts into plasma was determined by immunoaffinity chromatography. In normal plasma the major component of efflux of sterol radioactivity from labeled fibroblasts was dependent upon unassociated apo A-I. In LCAT-deficient plasma, apoprotein-dependent efflux was largely a function of unassociated apo E. When fibroblasts were incubated with fibrinogen-free unfractionated LCAT-deficient plasma, there was no spontaneous net transport of sterol either into or from the cells, indicating that efflux and influx rates were in balance. When apo E was removed by affinity chromatography, there was net transport from plasma to cells. These findings suggest a novel metabolic role for apo E in the promotion of sterol transport uncoupled to LCAT-activity.

Apolipoproteins↗
PubMed1999

Classical LCAT deficiency resulting from a novel homozygous dinucleotide deletion in exon 4 of the human lecithin: cholesterol acyltransferase gene causing a frameshift and stop codon at residue 144.

Lecithin: cholesterolacyltransferase (LCAT) transacylates the fatty acid at the sn-2 position of lecithin to the 3beta-OH group of cholesterol forming lysolecithin and the majority of cholesteryl ester found in plasma. LCAT participates in the reverse cholesterol transport pathway in man where it esterifies tissue-derived cholesterol following efflux from peripheral cells into HDL. Only 38 unique mutations in the human LCAT gene have been reported worldwide. Our French female proband presented with corneal opacity and no detectable plasma LCAT activity using either endogenous or exogenous assays. Her total plasma cholesterol and HDL cholesterol were low (2.34 mmol/l and 0.184 mmol/l, respectively) with a very high cholesterol/cholesteryl ester molar ratio (10.9:1). Plasma triglycerides were 0.470 mmol/l with low apo B (40.5 mg/dl), apo A-I (14.7 mg/dl), apo A-II (6.8 mg/dl) and apo E (2.1 mg/dl) levels. Plasma lipoprotein analysis by ultracentrifugation showed very low HDL concentrations and a characteristic shift of the lipoprotein profile towards larger, less dense particles. No proteinuria, renal dysfunction or signs of atherosclerosis were noted at age 45. Sequence analysis of her LCAT gene showed a novel homozygous TG-deletion at residues 138-139 that resulted in a frameshift causing the generation of a stop codon and premature termination of the LCAT protein at amino acid residue 144. Western blotting of the patient's plasma using a polyclonal IgY primary antibody against human LCAT failed to demonstrate the presence of a truncated LCAT protein. A 53 bp mismatched PCR primer was designed to generate an Fsp 1 restriction site in the wild type sequence of exon 4 where the mutation occurred. The 155 bp PCR product from the wild type allele produced a 103 bp and 52 bp fragment with Fsp 1 and no cleavage products with the mutant allele thus permitting rapid screening for this novel mutation.

Adolescent↗
PubMed1975

Lipoprotein and lecithin: cholesterol acyltransferase changes in galactosamine-induced rat liver injury.

Abnormal lipoproteins and drcreased lecithin: cholesterol acyltransferase activity are found in rat plasma following intraperitoneal injection of D-galactosamine. The changes observed, including absence of alpha-lipoprotein and the presence of lipoproteins rich in phospholipid and unesterified cholesterol but deficient in cholesteryl esters, are remarkably similar to changes found in human pathologic states of lecithin: cholesterol acyltransferase deficiency. When examined by electron microscopy, all of the major lipoprotein classes isolated by ultracentrifugation showed morphological abnormalities including the formation of rouleaus consisting of disk-shaped particles.

Acyltransferases↗
PubMed1961

Further studies on seroreactivity in leprosy by means of a lecithin-free cardiolipin antigen (cardchol) and other antigens ordinarily used in the serodiagnosis of treponematoses.

In a previous study the reactivities of some lipoidal antigens in sera from patients with different types of leprosy were investigated. The present paper is a continuation of this earlier study and relates to an investigation of some 300 sera from leprosy patients in India. In particular, the reactivity of cardchol (a complement-fixing, lecithin-free, cardiolipin antigen) is compared with that of CWRM (an "ordinary" cardiolipin antigen used in routine complement-fixation tests for the serodiagnosis of treponematoses).Cardchol, which is inferior to CWRM in reactivity with treponemal sera, has proved to be more reactive than CWRM in leprosy sera. The use of a lecithin-free cardiolipin antigen in serological investigations has revealed that the antilipoidal antibodies occurring in leprosy are most probably different from those demonstrated in treponematoses. Among the sera of non-syphilitic lepers, the percentage reactivity was significantly higher with cardchol than with CWRM. Thus, by changing the relative proportions of the three components of cardiolipin antigen, it has been possible to produce antigens with reactivities quite different from those of the antigens ordinarily used for the serological demonstration of syphilis.Cardchol is by no means a specific antigen for the demonstration of leprosy, but it has the ability to fix antibodies in certain leprosy sera that are not fixed by the ordinary CWRM antigen.

Antibodies↗
PubMed1975

Plasma lipoproteins in familial lecithin: cholesterol acyltransferase deficiency: effects of dietary manipulation.

To study the metabolism of the abnormal plasma lipoproteins in familial lecithin:cholesterol acyltransferase deficiency we performed five dietary experiments designed to perturb their distribution and composition. Four patients with the disease were given successive diets that differed in triglyceride, carbohydrate, or cholestrol content, and after each dietary period the lipoproteins were analyzed by combinations of preparative and analytical ultracentrifugation, gel filtration, chromatography, and disc gel electrophorsis. Lowering the intake of long chain, dietary triglyceride descreased the concentrations of the large very low density lipoproteins, the large and intermediate low density lipoproteins, and the small high density lipoproteins by as much ad 79 %, but either increased or did not change the concentrations of the small very low and low density lipoproteins. Re-adding long chain triglycerdine to the diet generally reversed these effects, but increasing the dietary cholesterol without lowering the dietary triglyceride only decreased the concentration of plasma cholesteryl ester. We conclude that the concentrations of the large very low and low sensity lipoproteins, the intermediate-sized low density lipoproteins, and the small high density lipoproteins are related to the absorption and subsequent transport of long chain dietary fatty acids. Since these lipoproteins are rich in unesterified cholesterol and lecithin, two polar lipids that form a substantial part of the surfaces of chylomicrons, components of chylomicron surfaces may accumulate in the patient's plasma following enzymic removal of chylomicron triglyceride and contribute to several of the abnormal lipoproteins.

Acyltransferases↗
PubMed1977

Abnormal plasma lipoproteins and lecithin-cholesterol acyltransferase deficiency in alcoholic liver disease.

Serial studies of plasma lipids and lipoproteins were performed in 4 patients with acute alcoholic liver disease characterized by a massive fatty liver and laboratory evidence of intrahepatic cholestasis. There were striking alterations in the plasma lipoprotein electrophoretic patterns characterized by the absence of alpha- and pre-beta-lipoprotein bands and the presence of a single band of abnormal mobility. These changes were associated with an extreme decrease in plasma lecithin-cholesterol acyltransferase activity, resulting in greatly reduced levels of plasma cholesteryl esters and increased levels of unesterified cholesterol. In 2 patients hypertriglyceridemia and hypercholesterolemia were present, the latter because of an increase in unesterified cholesterol. Lipoproteins were isolated from the plasma by sequential ultracentrifugation at the densities used for separation of normal very low density, low density, and high density lipoproteins; however, the patients' lipoproteins were different from normal in lipid composition and ultrastructure. All of the lipoprotein fractions were decreased in cholesteryl esters and the major lipoprotein was a triglyceride-rich low density lipoprotein. Electron microscopic studies of the low and high density lipoprotein fractions revealed the presence of bilamellar vesicles and stacked discs. All of the changes in lipoprotein composition and ultrastructure gradually returned to normal with clinical improvement. These observations indicate that alcoholic liver injury is associated with profound alterations in lipoprotein composition and metabolism which may be related in part to lecithin-cholesterol acyltransferase deficiency.

Acyltransferases↗
PubMed1978

Lecithin:cholesterol acyltransferase deficiency associated with hepatic schistosomiasis mansoni.

Plasma and erythrocyte lipid abnormalities occur in chronic human schistosomiasis mansoni and appear to be related to mild lecithin:cholesterol acyltransferase (LCAT) deficiency. Plasma LCAT activity is about 50% lower than normal in decompensated hepatosplenic schistosomiasis, whilst the plasma concentrations of cholesteryl ester and lysolecithin and decreased and that of lecithin increased in the earlier hepatointestinal and compensated hepatosplenic forms of the disease as well as in the later decompensated stage. Plasma lipoproteins are also altered in schistosomiasis. Agarose gel electrophoresis showed reduced alpha and pre-beta lipoproteins, whilst other studies consistently showed that lipoproteins from patient plasma are better substrates for LCAT than those of normal plasma. Erythrocyte cholesterol is increased in all forms of the disease, and the cells show increased resistance to lysis either in hypotonic media or in 0.3 M glycerol. The severity of these lipid changes clearly shows a gradation through the successive stages of the disease. In the experimentally infected mouse LCAT deficiency does not seem to be a feature of the disease, but several significant changes in plasma and erythrocyte lipids occur which contrast with those seen in human schistosomiasis.

Adult↗
PubMed1994

Lecithin-cholesterol acyltransferase deficiency: first report of case in a United States citizen.

Lecithin-cholesterol acyltransferase is responsible for the formation of most cholesteryl esters in plasma. Absence of this enzyme can result in a rare syndrome that includes diffuse corneal opacities, normocytic normochromic anemia, proteinuria, renal failure, and premature arteriosclerosis. The deficiency can be inherited in an autosomal recessive manner, or it can be acquired through liver disease. Diagnosis requires a high index of suspicion and documentation of impairment of enzyme mass or activity (or both). This article includes a case report of the first United States citizen known to have lecithin-cholesterol acyltransferase deficiency. The authors review the literature related to this disease.

Adult↗
PubMed1983

Oral physostigmine and lecithin improve memory in Alzheimer disease.

Eight patients with early Alzheimer disease were treated with gradually increasing multiple daily doses of oral physostigmine and supplemental lecithin. Six individuals showed improvement in total recall and retrieval from long-term storage (LTR), with a decrease in intrusions (a measure of inaccurate recall). The optimal individual dose was either 2.0 or 2.5 mg of physostigmine for each responding patient. Results of this open trial were subsequently replicated during a double-blind crossover trial comparing physostigmine treatment to placebo. All six patients again demonstrated improvement in total recall and LTR, with a decrease in intrusions. The decrease in intrusions was strongly correlated with increasing inhibition of cholinesterase activity in cerebrospinal fluid, suggesting that the degree of improvement in the patient's memory was related to the amount of physostigmine that reached the brain. Other neurotransmitters and metabolites in cerebrospinal fluid were unaffected by the physostigmine therapy, suggesting a specific effect of physostigmine on the cholinergic system. The results suggest that small oral doses of physostigmine combined with lecithin ingestion have therapeutic benefit for some patients with Alzheimer disease.

Aged↗
PubMed1978

Peturbation of lymphocyte response to concanavalin A by exogenous cholesterol and lecithin.

Incubation of lymphocytes with lecithin liposomes enriched with cholesterol, elevated the cholesterol level of the cells relative to phospholipids. Treatment of lymphocytes with pure lecithin liposomes resulted in the converse effect. Both these treatments resulted in suppression of the induction phase of the response to concanavalin A and were practically reversible. It is suggested that these changes induce modulations of the fluidity of the lymphocyte membrane which may also take place in vivo by serum lipoproteins. Based on this study, the possible effects of lipids on lymphocyte activation are discussed.

Animals↗
PubMed1994

Ultra-long-duration local anesthesia produced by injection of lecithin-coated tetracaine microcrystals.

This study was designed to determine if microencapsulated tetracaine would provide a longer duration of local anesthesia than nonmicroencapsulated (neat) tetracaine. Local anesthesia was determined by monitoring the response of the rat to tail clamping after the installation of a subcutaneous ring block. Ten percent microencapsulated tetracaine was found to provide local anesthesia of the tail for a 43-hour duration. Ten percent tetracaine solution was toxic. One percent tetracaine solution provided a tail block lasting 8 hours. Lecithin membranes without drug provided no block. This study demonstrates that lecithin-coated tetracaine microcrystals produce a local anesthetic effect that is ultra-long in duration, reversible, and not systemically toxic.

Anesthetics, Local↗
PubMed1977

The relationship of amniotic fluid insulin levels and the lecithin-sphingomyelin ratio.

Amniotic fluid insulin levels and the lecithin-sphingomyelin ratio were determined in 62 samples of 33 insulin-dependent diabetic patients from the 29th to the 44th week of gestation inclusive and in 42 samples of 38 gestational diabetic patients from the 35th to the 43rd week of gestation inclusive. (Gestational age was measured by ultrasonography.) The level of insulin in the amniotic fluid did not appear to affect the lecithin-sphingomyelin ratio.

Amniotic Fluid↗
PubMedDate not supplied

Correlation of optical density, lecithin and lecithin/sphingomyelin ratio in amniotic fluid.

The correlation between optical density at 650 nm, lecithin and lecithin/sphingomyelin ration was investigated in 94 amniotic fluid samples obtained from 90 patients between 28 and 40 weeks of pregnancy. All samples were processed immediately and those contaminated with blood or meconium were discarded. The correlation coefficient between lecithin and absorbance was high (0.926). The lecithin/sphingomyelin ratio also had a good correlation coefficient with the optical density (0.768). We conclude that absorbance at 650 nm is a reliable test for assessing fetal lung maturation.

Amniotic Fluid↗
PubMed1975

Molecular arrangement in monolayers containing cholesterol and dipalmitoyl lecithin.

The molecular arrangement of dipalmitoyl lecithin and cholesterol in mixed monolayers was investigated with the aid of a physical model. The two lipids are miscible at the surface, but there is no indication of a specific interaction. In equimolar mixed monolayers at 25 and 37 degrees, the lipids are in tail contact. Lecithin molecules are able to remain hydrated in the mixed monolayers at high values of surface pressure.

Chemical Phenomena↗