Abnormal apolipoproteins in high density serum lipoproteins in dyslipoproteinaemia of severe trauma

Myocardial injury: the acute phase response and lipoprotein metabolism

Myocardial infarction and other types of tissue injury generate changes in plasma proteins known as the acute phase response. Variations in lipid and lipoprotein levels after acute myocardial infarction are manifest within 24 to 48 h after the onset of chest pain. Maximal postinfarction reductions in total cholesterol occur at days 4 to 5 with levels 47% below baseline; low and high density lipoprotein cholesterol fractions decrease to their nadir on day 7 to concentrations that are 48% and 32% below baseline, respectively. Triglyceride levels increase after acute myocardial infarction to a maximal level that is 58% above baseline on day 7. These alterations in lipid and lipoprotein levels generally stabilize by 2 months after the acute event. Screening for dyslipidemias in survivors of myocardial infarction requires clinical decision-making based on accurate and reliable measurements. The clinician must be familiar with characteristic changes in acute phase lipids and lipoproteins to ensure that patients receive appropriate, potentially life-saving therapy.

Lipid and apolipoprotein changes after orthotopic liver transplantation for end-stage liver diseases

Orthotopic liver transplantation was performed in 37 patients with different endstage liver diseases. Changes in lipid and apolipoprotein concentrations were followed daily from day 1 to 20 after surgery and regularly thereafter until 12 months. When the acute effects of surgery had cleared away, there was a sharp drop in HDL-C, apo A-I and A-II from day 1 to 5, a stabilization at their lowest values from day 5 to 15 and then a progressive rise. Contrasting with this drop, triglycerides, apo B, C-II and C-III increased from day 1 to 5 with variable concentrations thereafter. Apo SAA considerably increased early after surgery and remained significantly higher than normal in most patients after 12 months. All other parameters returned to normal from 3 to 6 months after transplant. The mechanism leading to these lipid and apolipoprotein changes are discussed with respect to the distant effect of infusions, re-alimentation, immunosuppressive therapy and lipoprotein metabolism. The apolipoprotein concentrations appear very useful indicators of functional liver recovery.

Alterations in lipoprotein density classes in infantile visceral leishmaniasis: presence of apolipoprotein SAA

This study describes the alterations in the plasma lipoproteins from nine young Tunisian children with active visceral Leishmaniasis. The plasma lipid profile from affected patients was characterized by a marked hypertriglyceridaemia associated with reduced levels of total and high density lipoprotein (HDL)-cholesterol and a significant increase in the plasma ratio of unesterified to total cholesterol. Quantitative determination of plasma apolipoproteins revealed significantly decreased levels of all measured apolipoproteins, especially of apolipoproteins A-I and A-II, with the exception of apolipoprotein E, the levels of which were markedly increased. Moreover, at least two isoforms of the apolipoprotein serum amyloid A (SAA), an acute phase protein, were detected in all patients' plasma using two-dimensional electrophoresis. Immunochemical evidence was presented that apolipoproteins E and SAA, although both primarily associated with apolipoprotein A- (A-I and A-II) as well as with apolipoprotein B-containing lipoproteins, could occur as LP-E and LP-SAA subspecies, devoid of apolipoproteins A and B. However, it should be pointed out that LP-SAA particles were found in HDL2 from only two patients whereas the abnormal LP-E particles were detected in LDL and HDL2 from all investigated patients. The polydispersity and heterogeneity of patients' HDL3 were assessed by electron microscopy. It was further suggested that the profound changes in the lipoprotein metabolism of these young patients may be due to the increased hepatic synthesis of apolipoprotein SAA and/or to their altered immune function during active visceral Leishmaniasis.

Detection of human serum amyloid A protein in very low density--and high density lipoproteins of patients after acute myocardial infarction

Two acute-phase proteins have been identified in very low density (VLDL)- and high density lipoproteins (HDL) of patients after acute myocardial infarction. Both proteins have a relative molecular weight of 11,000 and isoelectric points pI 6.08 and 6.27, and do not contain cysteine or sugar residues. Polyclonal antibodies to these acute phase reactants did not cross-react with other serum apolipoproteins. Evidence is given that both proteins are polymorphic forms of the human serum amyloid A protein.

Two-dimensional electrophoresis of plasma proteins and high density lipoproteins during inflammation

Plasma protein and lipoprotein fractions of five patients were analyzed on day 1, 5, and 15 after severe head injury by combining three types of two-dimensional electrophoresis (2-DE) to obtain information on lipoprotein and apolipoprotein composition. On analysis under nondenaturing conditions in both dimensions on day 5, the samples show modifications of isoelectric point (pI) and molecular weight (Mr) properties of the high density lipoprotein (HDL) fraction in addition to an increase in inflammatory proteins and a return to a normal pattern on day 15. In the second type of 2-DE the samples were analyzed employing isoelectric focusing without denaturant in the first dimension, followed by sodium dodecyl sulfate (SDS) in the second dimension in order to study the protein composition of lipoprotein fractions. On day 5, a decrease of the apolipoproteins apo A-I, apo A-II, and apo C were noted, with simultaneous appearance of an unidentified protein with Mr 12,000 and pI 6.0. In the third type of 2-DE, employing urea and Nonidet P-40 in the first and SDS in the second dimension, the plasma polypeptide composition was studied. The presence of an unidentified polypeptide could be confirmed on day 5, tending to disappear thereafter. This Mr 12,000 component consists of two major spots at pI 5.7 and 6.0 and four minor ones between pI 6.0 and 8.0. These properties suggest that this protein corresponds to serum amyloid A apolipoprotein.

Time course for the changes of serum lipoproteins and apolipoprotein T concentrations after major surgical trauma in man

Trauma induces changes in the serum lipoprotein pattern in man. A characteristic apolipoprotein, named apolipoprotein T existing in its isoforms T-I to T-IV, in the high density lipoprotein (HDL) fraction of serum, also appears in response to trauma. In this report eight patients operated on for abdominal aortic aneurysms were studied concerning the time dependency in changes of serum lipoproteins and the appearance of apolipoprotein T. Blood samples for lipoprotein analysis were taken preoperatively, postoperatively on days 1, 2, 4, 6 and thereafter twice a week until discharge from the hospital. The serum lipoprotein concentrations were compared with those from a group of healthy men. The most striking abnormalities were found in serum VLDL where both concentrations of triglycerides and cholesterol decreased during the first 2 days by more than 50%, compared to the initial level, and remained low for about 1 week. Also the concentration of LDL cholesterol in serum decreased about 40% from the preoperative value during the first days. Serum HDL cholesterol either increased during the first 2 days in those patients with a low preoperative concentration or stayed on a subnormal level during the first 4 days. After day 4 the serum HDL cholesterol decreased and reached the minimum level on days 10 to 13. Already on day 1 after trauma apolipoprotein T had reached a high level in order to stay high for several weeks. The apolipoprotein T isoforms had different appearance with time and varied independently of serum cholesterol in HDL.

Trauma, high density lipoproteins, and serum amyloid protein A

Several apoproteins not readily detectable in normal serum lipoproteins were found in markedly increased amounts in the lipoprotein density interval 1.125-1.21 g/ml (HDL3) of serum obtained from victims of severe trauma. Following electrophoretic separations, they were shown to be isotypes of the acute-phase protein serum amyloid A (SAA) by immunoreaction with antiserum to the structurally related tissue amyloid protein A (AA). The two principal apoSAA isotypes in the HDL3 of trauma patients appear to be identical to the two principal isotypes (apoSAA1 and apoSAA2) previously isolated from the HDL3 of pooled serum representing an unselected patient population. Concentrations of apolipoproteins A-I and A-II in the HDL3 of the trauma patients were significantly lower than in the HDL3 of normal serum. Evidence is presented that several recently described 'new' families of HDL apoproteins, all of an acute-phase nature, are SAA apoproteins, which are emerging as sensitive indicators of tissue damage.