The prothrombin G20210A mutation: a new high-prevalence congenital risk factor for thrombosis.
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Factor V↗
Biomedical subjects
M Laposata
Publications and source records attributed to M Laposata.
Fatty acid ethyl ester synthesis in the preparation of scotch whiskey.
Fatty acid ethyl esters (FAEE), nonoxidative ethanol metabolites present in human organs commonly damaged by ethanol abuse, have been implicated as mediators of organ damage. FAEE are additives in various foods and beverages to provide flavor or fragrance, and therefore are common dietary lipid constituents. We hypothesized that FAEE could be generated during alcoholic beverage production because fatty acids are present within microorganisms and ethanol is generated during the fermentation process. In this report, we demonstrate that FAEE are present in commercially available scotch beverages, and that in the preparation of scotch, FAEE can be produced during the fermentation reaction as a result of FAEE synthase activity in the yeast. Following ingestion of scotch, preformed FAEE are delivered to GI tract. The consequences of ingestion of FAEE in scotch, if any, remain to be determined.
Acyltransferases↗
The hydrolysis of fatty acid ethyl esters in low-density lipoproteins by red blood cells, white blood cells and platelets.
Fatty acid ethyl esters (FAEE), esterification products of fatty acids and ethanol, have been implicated as toxic mediators of ethanol ingestion. In this study, we investigated the in vitro hydrolysis of FAEE reconstituted in low-density lipoproteins (LDL) when incubated with human blood, cell free plasma, red blood cells, white blood cells, and platelets. We also determined the metabolic fate of the fatty acid originally incorporated in the FAEE following FAEE hydrolysis. When FAEE were incubated with human red blood cells. white blood cells, or platelets, at physiologic cell counts, 80% of the FAEE were hydrolyzed at 2 h. The FAEE-derived fatty acid was predominantly found in phospholipid and free fatty acid fractions. Cell free plasma contained minimal FAEE hydrolytic activity. These studies demonstrate that FAEE are degraded to free fatty acids and ethanol by the cellular elements in the blood. The generation of free fatty acids from extensive hydrolysis of FAEE adds support to the growing concept that at least some of the toxic effects of FAEE are mediated by the free fatty acids generated upon hydrolysis of the ethyl esters.
Alcoholism↗
Assessment of ethanol intake. Current tests and new assays on the horizon.
The number of tests used for the detection of ethanol ingestion is increasing. The field is rapidly moving beyond ethanol alone as a marker of ethanol intake. The combined measurement of carbohydrate deficient transferrin, FAEEs, 5-HTOL/5-HIAA, acetaldehyde adducts, and phosphatidylethanol may one day be used to approximate the time and amount of ethanol ingestion. The ultimate configuration of a panel of tests for monitoring ethanol intake awaits the results of studies that identify the clinical usefulness of each marker.
Acetaldehyde↗
D-dimers in the diagnosis of pulmonary embolism.
The aim of this study was to determine if the absence of circulating D-dimers, as determined by latex agglutination assays, can correctly exclude the presence of pulmonary embolism using pulmonary angiography as the diagnostic endpoint. Blood samples were obtained prospectively at the time of angiography for suspicion of acute pulmonary embolism. Plasma was assayed for D-dimer by five different latex agglutination assays. Angiographic evidence of pulmonary emboli was found in 34% (35/ 103) of patients. The latex agglutination assays had sensitivities of 97 to 100% and specificities of 19 to 29%. The negative predictive value was 94 to 100%. However, a negative D-dimer was rare in patients with recent surgery, malignancy, or total bilirubin > 34 micromol/L (> 2 mg/dl). In 31 patients suspected of pulmonary emboli but without these confounding factors, the five D-dimer assays were negative in 46 to 55% of patients with normal pulmonary angiograms. The negative predictive value in these patients was 100% by all five latex agglutination assays tested. The latex agglutination assays for D-dimer, when the pulmonary angiogram is used as the diagnostic endpoint and in the absence of recent surgery, malignancy, or liver disease, appears to be a clinically useful test in the diagnosis of acute pulmonary embolism.
Aged↗
A method for proficiency testing of small peer groups in the College of American Pathologists Coagulation Surveys.
OBJECTIVE: To develop a grading scheme for the proficiency testing of small peer groups of fewer than 10 members for the prothrombin time (PT) and activated partial thromboplastin time (APTT). METHODS: A modified target value for small peer groups was derived based on the assumption that measurement variability in the PT and APTT is more greatly influenced by variations in reagents than in instruments. Criteria for grading were established by statistical simulation to achieve misclassification errors of less than 5% for both incorrectly passing and failing participants. College of American Pathologists Coagulation Survey data were analyzed to determine the number of additional laboratories graded using the proposed scheme, as well as the failure rates among participants in the small peer groups. RESULTS: The modified target value for small peer groups is a weighted average between the mean of the peer group and the mean of all participants using the same reagent (reagent group). Peer groups with as few as 4 members can be graded provided that specific criteria are satisfied: there must be at least 5 peer groups for the same reagent, at least 3 of these 5 peer groups must have more than 3 members, and the coefficient of variation for the reagent group must be less than 10%. This proposed grading scheme decreased the number of ungraded laboratories by 44% to 46% for the PT and 42% to 55% for the APTT. The percentage of failing grades among participants in the small peer groups ranged from 1.3% to 4.1% for the PT and 1.4% to 7.2% for the APTT. These failure rates were 2.8- to 13.0-fold higher than the failure rates in large peer groups (P < or = .05). CONCLUSIONS: The proposed small peer group grading scheme can improve the effectiveness of College of American Pathologists proficiency testing for the PT and APTT and may also be generally applicable to other test methods and analytes.
Anticoagulants↗
Preanalytical variables affecting the quantification of fatty acid ethyl esters in plasma and serum samples.
BACKGROUND: Fatty acid ethyl esters (FAEEs) are cytotoxic nonoxidative ethanol metabolites produced by esterification of fatty acids and ethanol. FAEEs are detectable in blood up to 24 h after ethanol consumption. The objective of this study was to assess the impact of gender, serum or plasma triglyceride concentration, time and temperature of specimen storage, type of alcoholic beverage ingested, and the rate of ethanol consumption on FAEE concentrations in plasma or serum. METHODS: For some studies, subject were recruited volunteers; in others, residual blood samples after ethanol quantification were used. FAEEs were isolated by solid-phase extraction and quantified by gas chromatography-mass spectrometry. RESULTS: For weight-adjusted amounts of ethanol intake, FAEE concentrations were twofold greater for men than women (P </=0.05). Accounting for triglycerides improved the correlation between blood ethanol concentrations and FAEE concentrations for both men (from r = 0.640 to r = 0.874) and women (from r = 0.619 to r = 0.673). FAEE concentrations did not change when samples were stored at or below 4 degrees C, but doubled when stored at room temperature for >/=24 h. The type of alcoholic beverage and rate of consumption did not affect FAEE concentrations. CONCLUSION: These studies advance plasma and serum FAEE measurements closer to implementation as a clinical test for ethanol intake.
Alcohol Drinking↗
Fatty acid ethyl esters: ethanol metabolites which mediate ethanol-induced organ damage and serve as markers of ethanol intake.
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Alcohol Drinking↗
Laboratory evaluation of hypercoagulable states.
The number of well-characterized hereditary and acquired hypercoagulable conditions is increasing, such that in many thrombophilic patients, the laboratory can now identify a hypercoagulable condition. This review describes the currently known hypercoagulable states that predispose patients to venous, and in some instances, arterial thrombosis. For each condition, the discussion includes the incidence, magnitude of the thrombotic risk in the general population in comparison with symptomatic families, synergistic interactions among the various hypercoagulable conditions, molecular pathogenesis, and interpretation of laboratory test results. In addition, recommendations for laboratory testing are summarized.
Blood Coagulation Tests↗
Collagen-induced whole blood platelet aggregation in patients undergoing surgical procedures associated with minimal to moderate blood loss.
Intraoperative bleeding due to platelet disorders is a persistent problem. Therefore, a screening assay to identify patients who are likely to bleed as a result of platelet dysfunction would be useful in formulating decisions about patient care. A previous study indicated that preoperative collagen-induced whole blood platelet aggregation predicts bleeding in patients undergoing surgery with cardiopulmonary bypass, a procedure associated with substantial blood loss. In the current study, we assessed the ability of the same whole blood platelet aggregation test to predict blood loss in patients undergoing surgical procedures not associated with substantial blood loss. The study included 369 adult patients (165 men and 204 women). Patients were categorized in three groups depending on the invasiveness of the operation and the expected blood loss. The intraoperative estimated blood loss value, obtained from the operative report in the patient record, increased significantly with increasing surgical invasiveness. Patients with excessive blood loss (defined as blood loss at or above the 75th or 90th percentile of the estimated blood loss values of patients undergoing procedures of similar invasiveness) had similar platelet aggregation values as patients who did not experience excessive blood loss. Thus, for patients undergoing operations not associated with substantial blood loss, the results of preoperative collagen-induced whole blood platelet aggregation are not effective in identifying patients likely to experience excessive blood loss.
Blood Coagulation Tests↗
Fatty acid ethyl esters and HepG2 cells: intracellular synthesis and release from the cells.
Fatty acid ethyl esters (FAEE), esterification products of fatty acid and ethanol, have been implicated as mediators of ethanol-induced organ damage. To understand the molecular and cellular events in FAEE synthesis and secretion, we developed a system in which HepG2 cells synthesize and release FAEE into the culture medium upon incubation with ethanol. The synthesis of FAEE was observed within 5 min of the addition of ethanol, with a plateau for FAEE synthesis after 2 h of incubation. It was also observed that FAEE are synthesized by both a microsomal FAEE synthase, which preferentially uses fatty acyl-CoA as a substrate, and a cytosolic FAEE synthase, which accepts both unesterified fatty acid and fatty acyl-CoA as substrates with a slight preference for fatty acyl-CoA. Although the kinetics of cellular FAEE synthesis await further characterization, the intracellular fatty acid substrate appears to be derived principally from glycerolipids and other esters. FAEE were released into the culture medium by a mechanism independent of the vesicular transport pathway. Lipoprotein particles and albumin were found to be carriers of FAEE after FAEE secretion from the cell.
Acyl Coenzyme A↗
Quantitation of the mass of fatty acid ethyl esters synthesized by Hep G2 cells incubated with ethanol.
Fatty acid ethyl esters (FAEE), esterification products of fatty acids and ethanol, have been increasingly implicated as mediators of ethanol-induced organ damage. The first goal of this study was to determine the mass of FAEE synthesized by Hep G2 cells exposed to a given dose of ethanol. The second goal was to determine whether all fatty acids in cells are equally available for FAEE synthesis. Hep G2 cells and essential fatty acid deficient Hep G2 cells (Hep G2-EFD) were used to study the synthesis of FAEE upon exposure to ethanol. A two-pool fatty acid model was created: (1) a "previously incorporated pool" formed by incubating the cells with 14C-labeled fatty acids for 24 hr; and (2) a "newly incorporated pool" formed by incubating cells with 3H-labeled fatty acids for 0.5 hr. The FAEE production from each pool was then determined. The total production of FAEE within 3 hr by Hep G2 cells in culture was 150 to 250 pmol/mg cell protein. The fatty acids most recently incorporated into the cells were preferred as substrates for FAEE synthesis because a higher percentage of fatty acids from the newly incorporated pool was used for FAEE synthesis than from the previously incorporated pool. Furthermore, a dose-response relationship was observed between the amount of fatty acid in the newly incorporated pool and FAEE production, but not between the amount of fatty acid in the previously incorporated pool and FAEE synthesis. Taken together, the results indicate that a relatively small amount of endogenously synthesized FAEE is generated from specific intracellular pools of fatty acid since not all fatty acids are equally available for FAEE synthesis. This indicates that if endogenous FAEE are toxic, they exert their toxic effect at very low intracellular FAEE concentrations.
Carcinoma, Hepatocellular↗
College of American Pathologists Conference XXXI on laboratory monitoring of anticoagulant therapy: the clinical use and laboratory monitoring of low-molecular-weight heparin, danaparoid, hirudin and related compounds, and argatroban.
OBJECTIVE: To review the role of the laboratory in monitoring therapy with low-molecular-weight heparin, danaparoid, hirudin, and argatroban, as reflected in the medical literature and the consensus opinion of recognized experts in the field. DATA SOURCES: Review of the medical literature and current clinical practice by a panel of 6 international experts in the field of anticoagulant therapy. DATA EXTRACTION AND SYNTHESIS: The experts made an extensive review of the published literature and prepared a draft manuscript, which included preliminary recommendations. The draft manuscript was circulated to participants in the College of American Pathologists Conference XXXI on Laboratory Monitoring of Anticoagulant Therapy prior to the conference. The manuscript and recommendations were then presented at the Conference for discussion. Recommendations were accepted if a consensus of the 26 experts attending the Conference was reached. The results of the discussion were used to revise the manuscript into its final form. CONCLUSIONS: This report reviews the mechanism of action and potential uses of these newer anticoagulant agents. General guidelines for monitoring these agents and 9 specific recommendations for laboratory monitoring of low-molecular-weight heparin and danaparoid are provided, along with citation of the appropriate supporting literature. Issues for which a consensus was not reached at the Conference are also discussed.
Anticoagulants↗
Anticardiolipin antibodies and hepatic artery thrombosis after liver transplantation.
BACKGROUND: Hepatic artery thrombosis (HAT) remains a devastating complication after liver transplantation. Various factors have been implicated in the pathogenesis of HAT, such as clotting abnormalities, increased hematocrit, and technical complications, but the role of anticardiolipin antibodies has not been evaluated. We investigated the possible association between HAT and anticardiolipin antibodies in adult patients who underwent liver transplantation. METHODS: Seven patients with HAT after orthotopic liver transplantation, 28 liver recipients without HAT, and 35 normal blood donors were evaluated. Determination of IgM and IgG anticardiolipin antibodies was performed by enzyme-linked immunosorbent assay using pretransplant serum from all allograft recipients. Clinical information was obtained from chart review. Fisher's exact test and Wilcoxon rank sum test were used for statistical analysis, and all P-values were two-tailed. RESULTS: Overall, 22 of 35 (63%) liver recipients had a positive anticardiolipin antibody test (either IgG or IgM titer >4 SD from the normal controls). The test was positive in 7 liver recipients (100%) with HAT compared with 15 out of 28 patients (54%) without HAT (P=0.031). As compared with liver recipients without HAT, patients with HAT also tended to have a higher mean anticardiolipin titer of IgG and IgM and a lower pretransplant platelet count; however, these differences were not significant. CONCLUSIONS: Our findings indicate that anticardiolipin antibodies are frequently elevated in patients with liver failure and may contribute to the pathogenesis of HAT after liver transplantation. Other potential consequences of anticardiolipin antibodies in end-stage liver disease remain to be determined.
Adult↗
Oral administration of unsaturated fatty acids: effects on human peripheral blood T lymphocyte proliferation.
Oils enriched in certain polyunsaturated fatty acids suppress joint pain and swelling in rheumatoid arthritis (RA) patients. Because T lymphocyte activation is important to propagation of joint tissue injury in patients with RA, we examined the effects of fatty acids administered by mouth in vivo on proliferation of human lymphocytes activated through the T cell receptor complex. T cell proliferation was reduced after oral administration of 2.4 g gammalinolenic acid in capsules of borage seed oil. Oral administration of oils enriched in linoleic acid, the parent n-6 fatty acid, and alpha linolenic acid, the parent n-3 fatty acid, did not influence growth of stimulated cells. Fatty acid analyses indicated that suppression of lymphocyte proliferation after gammalinolenic acid administration was associated with increased plasma and peripheral blood mononuclear cell concentrations of gammalinolenic acid and dihomogammalinolenic acid.
Administration, Oral↗
Pancreatic injury in rats induced by fatty acid ethyl ester, a nonoxidative metabolite of alcohol.
BACKGROUND & AIMS: The mechanism by which alcohol injures the pancreas remains unknown. Alcohol-intoxicated humans have high levels of fatty acid ethyl esters (FAEEs), nonoxidative products of ethanol metabolism, in blood, pancreas, and liver. The aims of this study were to determine whether FAEEs are toxic to the pancreas in vivo and, if so, to assess whether this injury is specific to the pancreas and to compare it to the injury observed in acute pancreatitis. METHODS: FAEEs were infused into Sprague-Dawley rats. Levels of FAEEs in plasma and pancreas were measured, and pancreatic injury was assessed during a 48-hour period for edema formation and ectopic trypsinogen activation and by light and electron microscopy. RESULTS: FAEEs induced highly significant increases in pancreatic edema, pancreatic trypsinogen activation, and vacuolization of acinar cells. These findings were specific to the pancreas and were not found in liver, lung, myocardium, skeletal muscle, or subcutaneous fat. CONCLUSIONS: FAEEs at concentrations found in human plasma produce a pancreatitis-like injury in rats, providing direct evidence that FAEEs can produce organ-specific toxicity. Thus, FAEEs may contribute to acute alcohol-induced damage to the pancreas.
Animals↗
Posttranslational modification of proteins with fatty acids in platelets.
Direct modification of proteins by fatty acid can occur as cotranslational N-myristoylation of an N-terminal glycine residue or as posttranslational thioesterification of cysteine residue(s). Platelets provide an excellent model system for studying the posttranslational type of modification in the absence of active protein synthesis and in the absence of protein synthesis-related protein modifications with lipids. Using this model system it was shown that thioesterification of proteins with fatty acid is less specific for palmitate than it was thought earlier and that other saturated, mono- and even polyunsaturated long chain fatty acids can also participate. The chain length and the extent of unsaturation of the protein-linked fatty acid moiety can, very likely, modulate hydrophobic protein-membrane lipid and protein-protein interactions. CD9, HLA class I glycoprotein, glycoproteins Ib, IX and IV, P-selectin and alpha subunits of G proteins have been demonstrated unequivocally as S-fatty acid acylated platelet proteins.
Acylation↗
Fatty acid acylation of platelet proteins.
A variety of fatty acids can become covalently attached to platelet proteins by thioester linkage. These fatty acids include palmitate, myristate, stearate, arachidonate, and eicosapentaenoate. More than 20 platelet proteins can be acylated by fatty acids. Several of the acylated platelet proteins have been identified, including glycoprotein Ib beta, glycoprotein IX, P-selectin, G-protein alpha subunits, and CD9. This report reviews the fatty acid acylation of platelet proteins.
Acylation↗