L. Hollaar

Assessment of myocardial damage in patients with acute myocardial infarction by serial measurement of serum α-hydroxybutyrate dehydrogenase levels

A method is presented for routine estimation of ultimate infarct size in patients with acute myocardial infarction (AMI). This method implies the calculation of the total quantity of alpha-hydroxybutyrate dehydrogenase (HBDH) released by the heart per liter of plasma, with the use of five to seven plasma samples per patient during the first 4 days after onset of infarction. The choice of HBDH for this purpose was motivated by a relatively small error in estimated enzyme release for slowly eliminated enzymes. The practicality of this method was studied in the coronary care unit at Leiden University Hospital where, in 1979, 146 patients with AMI were included in the study. In 100 patients (68%) HBDH-infarct size could be calculated precisely, and in 12 other patients (8%) the assessment of HBDH-infarct size was less accurate. In 34 patients (23%), HBDH-infarct size was unobtainable because of early death (eight cases), infarctions too small in size to assess or nonexistent (six cases), too much time elapsed since infarction (six cases), and incomplete plasma sampling (14 cases). Analysis of data shows that the larger HBDH-infarct sizes were found to be associated significantly with signs of heart failure, low stroke index and low ejection fraction, presence of tachycardias and interventricular conduction disturbances, high score of left ventricular wall motion abnormalities, large myocardial perfusion defect measured with thallium-201, in-hospital death, and death in the first year after infarction. A low but significant correlation was observed between HBDH-infarct size and the severity of coronary arterial lesions.

The activity of cardio-specific isoenzymes of creatine phosphokinase and lactate dehydrogenase in monolayer cultures of neonatal rat heart cells.

Monolayer cultures of neonatal rat heart cells, prepared according to Harary and Farley [12], contain, besides muscle cells (myoblasts, myocytes), a number of non-muscle cells (fibroblasts, endothelial cells) proliferating at a faster rate than the muscle cells. In ageing cultures of this type changes in enzyme and isoenzyme activities have been reported. These activity shifts have been interpreted either as an adaptation to hypoxic conditions, or as inherent to ageing of muscle cells. In this study we determined the changes in time of the activity of creatine phosphokinase including its isoenymes MM, MB and BB, and the activity of lactate dehydrogenase (LDH) including the isoenzyme combinations LDH1+2 and LDH3+4+5. It is shown that for creatine phosphokinase and its isoenzymes as well as for lactate dehydrogenase and its isoenzymes the activity changes in time are compatible with the hypothesis, that the isoenzyme shifts are the result of a change in the proportion of muscle cells in the culture, rather than an adaptation to hypoxia or ageing of the muscle cells. It is also demonstrated that inhibition of cell proliferation, by using a nutrient medium without serum, prevents the occurrence of these activity shifts.

Relationship between apolipoprotein E and low density lipoprotein particle size

The relationships between the particle size of low density lipoproteins (LDL) and various lipid parameters, including apolipoprotein (apo) E concentration and apo E phenotype, were analyzed in plasma samples obtained from 196 apparently healthy 35-year-old males. The LDL particle size was determined by gradient gel electrophoresis. Using stepwise multiple regression analysis it was found that LDL particle size correlated negatively to the plasma concentrations of triglyceride (r = -0.497, P < 0.001), apo E (r = -0.415, P < 0.001), apo B (r = 0.395, P < 0.001) and cholesterol (r = -0.235, P < 0.001) and correlated positively to the plasma concentrations of apo A-I (r = 0.297, P < 0.001) and apo A-II (r = 0.145, P < 0.05). However, the LDL particle size did not differ significantly among the different apo E phenotypes. Indeed, when entered as a variable in the multiple regression analysis, the apo E phenotype was not correlated to the LDL particle size. It is concluded that the LDL particle size is related to the plasma concentrations of triglyceride, apo E, apo B, apo A-I, apo A-II and cholesterol and is not affected by the apo E phenotype in healthy 35-year-old males.

Effect of simvastatin on the apparent size of LDL particles in patients with type IIB hyperlipoproteinemia

After 15 weeks of simvastatin therapy (20 mg/day), low density lipoprotein particle size in sera of 16 patients with type IIb hyperlipoproteinemia increased significantly from 233 +/- 5.0 A to 237 +/- 7.0 A (P less than 0.05), analyzed by 2-16% polyacrylamide gradient gel electrophoresis. Under simvastatin therapy the concentrations of total cholesterol, total triglyceride, very low density lipoprotein cholesterol and triglyceride, low density lipoprotein cholesterol and apolipoprotein B in serum fell significantly by 30%, 30%, 43%, 28%, 36% and 26%, respectively, and the concentration of high density lipoprotein cholesterol rose significantly by 14%. The changes of low density lipoprotein particle size induced by simvastatin therapy were correlated best with the changes of very low density lipoprotein triglyceride concentration (r2 = 0.438, P less than 0.01). Our results suggest that simvastatin therapy, additionally to a reduction of the serum cholesterol concentration, increases low density lipoprotein particle size which may contribute to reduction of the risk of coronary heart disease in patients with type IIb hyperlipoproteinemia.

The (ISO)enzyme activities of lactate dehydrogenase, α-hydroxybutyrate dehydrogenase, creatine kinase and aspartate aminotransferase in human myocardial biopsies and autopsies

In a study on enzyme activities in normal human myocardial tissue the activities of lactate dehydrogenase (LDH), alpha-hydroxybutyrate dehydrogenase (HBDH), creatine kinase (CK), and aspartate aminotransferase (AST), and the activities of the isoenzymes of LDH (1--5) and AST (c and m) were measured in myocardial specimens obtained from live patients (18 biopsies) and postmortem (14 autopsies). Comparison of measurements in 4 right ventricular biopsies from 1 patient with those in 9 right ventricular biopsies from 9 patients shows that (1) the enzymes studied are homogeneously distributed throughout the right ventricular myocardium, (2) errors in the measurement of the activities of the enzymes studied are within 5%, and (3) inter-individual differences in myocardial enzyme activities are quite considerable (10--17%). No significant differences in the activities of the enzymes studied were found between left and right ventricular myocardium. The effect of autolysis on the activities of the enzymes studied in myocardial specimens obtained postmortem is small, amounting to -1% to -6% in the first 10 h, irrespective of whether a linear or an exponential decay of enzyme activity is assumed. Comparison of myocardial enzyme activities in biopsies with those in autopsies, the latter being corrected for autolysis-induced inactivation, reveals significant differences with respect to CK, AST and mAST. At present it is impossible to conclude whether these differences were due to the different conditions existing before the myocardial specimens were frozen at -20 degrees C or to the different types of pathology present in the hearts from which the specimens were taken.

Cholesterol or Triglyceride Loading of Human Monocyte-Derived Macrophages by Incubation With Modified Lipoproteins Does Not Induce Tissue Factor Expression

Macrophages/foam cells localized in cholesterol- and triglyceride-rich regions of atherosclerotic plaques express high levels of tissue factor (TF), the essential cofactor and receptor of factor VIIa. It is not clear whether modified lipoproteins, for which several agonistic effects on macrophages have been described, are independent stimuli of TF expression in these cells. Therefore, we studied the effect of short-term (1 day) and long-term (4 to 7 days) incubation of human monocyte-derived macrophages cultured in suspension with modified and native LDLs or VLDLs on the expression of TF mRNA, antigen, and activity. We used native LDL or VLDL, moderately oxidized LDL or VLDL, severely oxidized LDL or VLDL, acetylated LDL, and beta-VLDL at a protein concentration of 100 microg/mL. Cholesterol loading occurred within 9 hours after the addition of acetylated LDL and continued during long-term incubation. Incubation of severely oxidized LDL for 7 days resulted in a slight increase in cholesterol content. Triglyceride loading was observed during short-term and long-term incubation with native and modified VLDLs. Neither cholesterol nor triglyceride loading resulted in expression of TF. Bacterial LPS still could induce TF expression in lipid-laden macrophages. Our results show that incubation with modified lipoproteins or lipid loading does not lead to TF expression in monocyte-derived macrophages cultured in suspension. This suggests that induction of TF expression in foam cells in the atherosclerotic lesion is triggered by additional or other components.

Extent of myocardial damage after open-heart surgery assessed from serial plasma enzyme levels in either of two periods (1975 and 1980).

Perioperative myocardial damage caused by cardiac surgery in 32 patients operated upon in 1980 is quantified in terms of total quantity of alpha-hydroxybutyrate dehydrogenase released from the heart into the circulation, and compared with perioperative myocardial damage in 32 patients operated upon in 1975. In the five year period between 1975 and 1980, various aspects concerning anaesthesia, pharmacological treatment, and myocardial preservation techniques have been subjected to considerable changes. Comparison of calculated myocardial damage in 1980 with that in 1975 shows a general reduction of about 40% in patients having coronary artery bypass grafting, 75% in patients with aortic valve replacement, and 10% in patients with mitral valve replacement.

Recognition and quantification of myocardial injury by means of plasma enzyme and isoenzyme activities after cardiac surgery.

Serial plasma enzyme determinations were carried out in 32 patients who underwent cardiac surgery with the aid of extracorporeal circulation. Plasma creatine kinase (CK), the cardiospecific isoenzyme of CK (CKMB), and alpha-hydroxybutyrate dehydrogenase (HBDH) were determined from the onset of surgery up to 100 to 120 hours after operation. From the plasma enzyme activities, the total amount of enzyme released by the injured heart into the circulation could be calculated using mathematical equations solved numerically by means of a computer. The calculated amount of CK, CKMB, and HBDH released by the heart correlated well with (1) postoperative mortality, and (2) peak activities of the respective enzymes. The calculated amount of any of the 3 enzymes released showed poor or no correlation with (1) electrocardiographic criteria of myocardial infarction, (2) duration of cardiopulmonary bypass, and (3) duration of total aortic cross-clamping. This study shows that the extent of myocardial injury after surgery can be assessed quantitatively using the calculated amounts of enzyme released, as well as using peak plasma activities of CKMB and HBDH.

Myocardial enzyme activities in plasma after whole-heart irradiation in rats.

Abstract Plasma levels of myocardial enzymes present after local heart irradiation were studied in a rat model. The purpose was to investigate whether, within days after irradiation, these enzyme levels change to such an extent that they may be helpful in assessing the severity of cardiac damage after radiotherapy. Therefore, activities of creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and α-hydroxybutyrate dehydrogenase (α-HBDH) were determined in the plasma and left ventricular myocardium of rats following local heart irradiation with a single dose of 20 Gy. A dose of 20 Gy is known to cause irreversible cardiac damage and to reduce survival times of the animals. Cardiac enzyme assays were performed directly after and twice daily for up to 2 weeks after radiation. Plasma CK, LDH, AST and α-HBDH levels were increased between 2 h and 24 h after irradiation. Plasma ALT levels remained unchanged. Myocardial enzyme levels, measured between 24 h and 16 days after radiation, did not differ between irradiated and control animals, although acute (first 12 h) reductions were observed in the irradiated group. The elevated enzyme levels in plasma appeared to correlate with the acutely reduced myocardial enzyme levels. Although irradiation with a dose of 20 Gy induced acute rises of cardiac enzyme levels in plasma, it is doubtful that fractionated radiation, as applied clinically for treatment of solid tumors, will induce plasma enzyme elevations that are large enough to indicate the extent of cardiac damage occurring acutely or chronically.

Effects of in vivo heart irradiation on myocardial energy metabolism in rats

To investigate the effect of in vivo heart irradiation on myocardial energy metabolism, we measured myocardial adenosine nucleotide concentrations and mitochondrial oxygen consumption in left ventricular tissue of rats 0-16 months after local heart irradiation (20 Gy). At 24 h and 2 months no difference in myocardial adenosine nucleotide concentration was apparent between irradiated and control hearts. The total myocardial adenosine nucleotide concentrations in irradiated hearts compared to those of nonirradiated controls tended to be lower from 4 months onward. The rate of oxidative energy production (state 3 respiration) in irradiated hearts was significantly reduced compared with that of age-matched controls from 2 months onward. Moreover, as a result of aging, a time-dependent decrease in the rate of oxidative energy production was observed in both irradiated and control hearts (P < 0.001). The respiratory control index (RCI = oxygen consumption in state 3/oxygen consumption in state 4) in irradiated hearts was not different from the RCI measured in age-matched control animals. During the period of study the RCI diminished significantly with age in both groups (P < 0.005). The number of oxygen atoms used per molecule of ADP phosphorylated (P/O ratio) was not influenced by the irradiation. The P/O ratio for the NAD(+)-linked substrates remained unchanged at a value of about 3 during the period studied. At 6 months after irradiation activities of myocardial enzymes such as lactate dehydrogenase, creatine kinase, citrate synthase, and cytochrome c oxidase were reduced. The reduction in myocardial energy production and the changes in energy supplies provide a mechanism to explain impaired contractility after local heart irradiation.