Covalently immobilized chemically modified lysozyme as a sorbent for bacterial endotoxins (lipopolysaccharides).

Chemical modification of lysozyme was carried out using benzaldehyde and anisaldehyde. It was shown that chemical modification affects only 1-2 amino groups of the protein molecule which does not prevent further covalent immobilization of lysozyme using the remaining free amino groups. The bacteriolytic activity of lysozyme is preserved after chemical modification and after subsequent covalent immobilization. As a result of chemical modification immobilized lysozyme more effectively adsorbs bacterial lipopolysaccharides (endotoxins). Adsorption of immunoglobulin G does not increase after modification. The sorbents obtained in this work can be used for the future development of new medical material for the extracorporeal treatment of sepsis. The proposed scheme for the modification and immobilization of lysozyme can be used with various aldehydes for the preparation of sorbents with different properties.

The bacteriolytic activity of native and covalently immobilized lysozyme against Gram-positive and Gram-negative bacteria is differentially affected by charged amino acids and glycine.

The emergence of new antibiotic-resistant bacterial strains means it is increasingly important to find alternatives to traditional antibiotics, such as bacteriolytic enzymes. The bacteriolytic enzyme lysozyme is widely used in medicine as an antimicrobial agent, and covalent immobilization of lysozyme can expand its range of possible applications. However, information on the effect of such immobilized preparations on whole bacterial cells is quite limited. Here, we demonstrate the differential effects of glycine and charged (basic and acidic) amino acids on the enzymatic lysis of Gram-positive and Gram-negative bacteria by soluble and immobilized lysozyme. Glycine and basic amino acids (histidine, lysine, and arginine) significantly increase the rate of lysis of Gram-negative Escherichia coli cells in the presence of soluble lysozyme, but they do not substantially affect the rate of enzymatic lysis of Gram-positive Micrococcus luteus. Glutamate and aspartate significantly enhance enzymatic lysis of both E. coli and M. luteus. When using immobilized lysozyme, the effects of amino acids on the rate of cell lysis are significantly reduced. For immobilized lysozyme, the presence of an external diffusion mode on cell lysis kinetics at bacterial concentrations below 4 × 108 colony-forming units·mL-1 was shown. The broadening of the pH optimum of lysozyme activity after immobilization has been demonstrated for both Gram-positive and Gram-negative bacteria. The Michaelis constant (Km) values of immobilized lysozyme were increased by 1.5-fold for E. coli cell lysis and 4.6-fold for M. luteus cell lysis compared to soluble enzyme. A greater understanding of the effect of amino acids on the activity of native and immobilized lysozyme is important for both the development of new materials for medical purposes and elucidating the interaction of lysozyme with bacterial cells. Of particular interest is our finding that lysozyme activity against Gram-negative bacteria is enhanced in the presence of glycine and charged amino acids over a wide range of concentrations.

Association of lipoprotein(a) level with short- and long-term outcomes after CABG: The role of lipoprotein apheresis.

OBJECTIVE: To evaluate the association of lipoprotein(a) [Lp(a)] level with short- and long-term outcomes after coronary artery bypass grafting (CABG) and to assess the effect of a 12 month course of weekly lipoprotein apheresis on vein graft patency and coronary atherosclerosis course in post-CABG patients with hyperlipidemia. METHODS: This study was performed in patients after successful CABG and consisted of three parts: a) a retrospective part with computed tomography assessment of vein graft patency in patients with first-year recurrence of chest pain after CABG (n = 102); b) a prospective trial with evaluation of cardiovascular outcomes during follow up time up to 15 years in relation to baseline Lp(a) levels (n = 356); c) an 12-months interventional controlled study in 50 patients with low-density lipoprotein cholesterol (LDL-C) levels >2.6 mmol/L prior to the operation despite statin treatment that allocated into 2 groups: active (n = 25, weekly apheresis by cascade plasma filtration (CPF) plus atorvastatin), and control (n = 25, atorvastatin alone). RESULTS: Patients subjected to computed tomography were divided in two groups: 66 (65%) with at least one vein graft occlusion and 36 (35%) without occlusions. Lp(a) levels were significantly higher in patients with occluded grafts with a median (95% confidence intervals (CI)) of 24 (17-42) mg/dL vs. 12 (6-24) mg/dL in patients with patent grafts, p < 0.01. Over a mean of 8.5 ± 3.5 years (range 0.9-15.0 years), the primary and secondary endpoints were registered in 46 (13%) and 107 (30%) patients, respectively. Patients with Lp(a) ≥30 mg/dL were at significantly greater risk for the primary endpoint (hazard ratio (HR) 2.98, 95% confidence interval (CI) 1.76-5.03, p < 0.001) and secondary endpoint (HR 3.47, 95%CI 2.48-4.85, p < 0.001) than patients with Lp(a) values <30 mg/dL. During the CPF procedure LDL-C levels decreased by 59 ± 14%, Lp(a) levels by 49 ± 15. The frequency of vein graft occlusions at study end was 14.3% (11 of 77) in the apheresis group and 27.4% (23 of 84) in the control group, p < 0.05. Progression of atherosclerosis was obtained in 26 (14.2%) segments of native coronary arteries in the apheresis group and in 50 (25.0%) segments of the control group. Regression signs were found in 30 (16.4%) and 19 (9.5%) segments, stabilization in 127 (69.4%) and 131 (65.5%) segments, respectively (χ2 = 9.37, p < 0.01). A Lp(a) level higher than 30 mg/dL was associated with a three-fold increased risk of vein grafts occlusion during first year after CABG, p < 0.001. CONCLUSION: Our data suggest that elevated Lp(a) is associated with a significantly increasing rate of one-year vein graft occlusions and adverse long-term cardiovascular outcomes whereas the use of lipoprotein apheresis improves vein graft patency during the first year after CABG.

Effect of specific lipoprotein(a) apheresis on coronary atherosclerosis regression assessed by quantitative coronary angiography.

AIM: To evaluate the effect of specific lipoprotein(a) [Lp(a)] apheresis on coronary atherosclerosis progression in coronary heart disease (CHD) patients with elevated Lp(a) levels. METHODS: A total of 30 subjects (mean age 53.5 ± 8.3 years, 70% male) with CHD verified by angiography, Lp(a) > 50 mg/dL, and low density lipoprotein cholesterol (LDL-C) ≤ 2.5 mmol/L on chronic statin treatment were prospectively evaluated for 18 months. Patients were allocated to receive specific Lp(a) apheresis, which was carried out weekly with Lp(a) Lipopak(®) columns (POCARD Ltd., Russia) (n = 15), or atorvastatin only (n = 15). Blinded quantitative coronary angiography analyses of percent diameter stenosis and minimal lumen diameter (MLD) were performed at baseline and after the 18-month treatment period. RESULTS: By the single specific Lp(a) apheresis procedure, Lp(a) level decreased by an average of 73 ± 12% to a mean of 29 ± 16 mg/dL, and mean Lp(a)-corrected LDL-C decreased by 7% to a mean of 1.4 mmol/L. Median percent diameter stenosis was reduced by -2.0 (95% confidence interval [CI], -5.0-0.0) with apheresis (p < 0.01 in comparison with baseline), and increased by 3.5 (0.0-6.9) with atorvastatin (p < 0.001 between the groups). The effect on MLD was more favorable with apheresis than with atorvastatin: 0.20 ± 0.39 mm, as compared with 0.01 ± 0.34 mm, p = 0.04. Lp(a) apheresis had greater efficacy regarding the amount of regressed/stabilized coronary segments than atorvastatin alone in the majority of patients (chi-square test 13.61, p < 0.005). CONCLUSION: Specific Lp(a) apheresis for 18 months produced coronary atherosclerosis regression in stable CHD patients with high Lp(a) levels and reached LDL-C goals.

Cascade plasma filtration during the first year after CABG in patients with hyperlipidemia refractory to statins.

OBJECTIVE: To evaluate the effect of a 12-month course of weekly lipid apheresis on vein graft patency after coronary artery bypass grafting (CABG) in patients with hyperlipidemia refractory to statins. METHODS: In a 12-month prospective controlled clinical trial we enrolled 34 male patients (mean age 57 ± 8 years) who passed through successful CABG and low-density lipoprotein cholesterol (LDL-C) level >2.6 mmol/L prior to the operation despite statin treatment. Patients were allocated into 2 groups: active (n = 17, weekly apheresis by cascade plasma filtration (CPF) plus atorvastatin), and control (n = 17, atorvastatin alone). Graft patency was evaluated by multislice computed tomography at 3 months and by angiography at 12 months after an operation. RESULTS: Both groups were comparable in clinical and biochemical characteristics. During each CPF procedure, LDL-C level decreased by 64 ± 9%, apoB - by 65 ± 8%, Lp(a) - by 52 ± 15%,; these changes were significant compared to baseline and the control group. Mean net difference in LDL-C level between apheresis and control groups was 1.1 ± 0.3 mmol/L. Vein graft patency at study end was 88.2% (45 of 51) in the apheresis group versus 72.7% (40 of 55) in the control group (p = 0.05). Use of apheresis was associated with decreased vein graft occlusions by 46%: relative risk 0.54; 95% confidence interval 0.27 to 1.02; p = 0.05. CONCLUSION: Our data suggest that the use of lipoprotein apheresis with CPF results in a better vein graft patency during the first year after CABG in patients with hyperlipidemia refractory to statins.

Ig apheresis for the treatment of severe DCM patients.

BACKGROUND: Autoantibodies against ß1-adrenoreceptor (AR) are considered by many authors to be the most significant in autoimmune process during DCM. Immunoadsorption (IA) of immunoglobulins (Ig apheresis) is a logic approach to remove autoantibodies against ß1-AR and other antibodies. The effect of Ig apheresis and the role of anti-ß1-AR in DCM are still an issue for discussion. METHODS: We have performed a prospective case-control study in 16 patients with DCM, NYHA Class II-IV congestive heart failure, positive and negative for anti-ß1-AR. RESULTS: We observed a clinically significant mean change of exercise tolerance compared with controls (6 MWT distance increased from 420 ± 130 m to 550 ± 150 m, p < 0.05). Systolic function improved rapidly by increase in LVEF from 28.6 ± 5.2% to 33.0 ± 10.3%, LV end-systolic and end-diastolic volumes decreased from 166 ± 58 mL to 148 ± 50 mL and from 235 ± 73 mL to 220 ± 73 mL, respectively, whereas in the control group there was no significant change in clinical variables. The improved quality of life and cardiac function in apheresis group as well as negative changes in control group didn't correlate with the presence of anti-ß1-AR. CONCLUSIONS: Ig apheresis for the treatment of DCM patients is associated with the improvement of quality of life and cardiac function regardless of the presence of anti-ß1-AR. We suggest that IgG apheresis is a safe and effective method for DCM patients.