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Effect of hypercholesterolemia on plasma viscosity
Thursday 13 October 1994: Poster Abstracts Rheology and henwdynamics
264
were similar in all genotypes. Subjects with E3 genotype had a lower dietary carbohydrate intake compared to E4 genotypes, but otherwise no significant differences were observed in dietary habits or in alcohol intake between different genotypes. Serum LDL-C was lower (P c 0.05) in men with the E2 genotype than in the E3 genotype. Median ape(a) level was significantly lower (P < 0.001) in the men with the Ecz genotype (95.5 U/l (57; 146)) than in the E3 genotype (178.5 U/l (144; 213)). As subjects with I?4 genotype may be at increased risk of CHD, the pnsent data could explain some of the discrepancies in reports of the role of ape(a) as a risk factor for atherosclerotic cardiovascular diseases. Determination of the fine specificity and molecular cloning of two monoclonal antibodies directed against the receptor-binding domain of human apolipoprotein E Raffdi, Rassart E, Weisgraber K, Innerarity T, Milne R, Lipo-
1
protein and Atherosclerosis Group, Univ. of Ottawa Heart Inst., 1053 Curling Ave., Ottawa, Ontario, Canada, KlY 4E9
The fine specificities of two monoclonal antibodies (mAbs) that sham a common epitope have been determined. mAbs lD7 and 2E8 which recognize the LDL receptor binding domain on human apo E have been found to share very similar fine specificities and
both am capable of displacing the LDL receptor from apo E. Substitutions in apo E that result in a loss of a positive charge at residues 142, 143, 145, 146 and 150 produce a decrease in the ability of the variant to bind to both antibodies and the receptor. However, apo E(Arg 136 + Ser) and apo E(Arg 158 + Cys) are defective with respect to LDL receptor binding but are indistinguishable from wild type apo E with respect to lD7 immunoreactivity. 2E8, on the other hand, shows a reduced reactivity apo E&g 158 + Cys) but normal binding to apo E(Arg 136 + Ser). As well, the introduction of proline residues at positions 144 and 152 decreases both antibody and receptor binding either by replacing a critical residue for binding or by disrupting apo E secondary or tertiary structure. The molecular clones of the light and heavy chains of both mAbs have been obtained and characterized in order to further define their respective binding specificities. Primary sequence analysis revealed that, although both light chains am similar, very little amino acid homology exists between the heavy chains. A striking pattern of four negatively charged amino acids present in the second complementarity determining region of the 2E8 heavy chain approximately aligns with acidic amino acids within the consensus sequence of the LDL receptor ligand binding domain. This could indicate that mAb 2E8 and the LDL receptor use a common mode of interaction with apo E.
RHEOLOGY AND HEMODYNAMICS
1 wP,
Effect of hypercholesterolemia on plasma viscosity %iek B, Univ. Clinical Centre, Trnovo Hospital of
Matsuo H, 2nd Dept. of Int. Med., Kagawa Med. Sch., 1750-I Ikenobe, Miki-cho, Kagawa 761-07, Japan
Internal Med., Ljubjljana, Slovenia
Increased concentration of plasma cholesterol may be atherogenic through affecting blood rheology. We have studied the relationship between plasma lipoproteins and plasma viscosity in healthy volunteers and in patients with peripheral arterial occlusive disease (PAOD). The study included a group (A) of 10 volunteers without risk factors for atherosclerosis or clinical evidence of PAOD; in group B were 15 patients with elevated plasma cholesterol (20% or more above normal value) and in group C were 39 patients with hypercholesterolemia and PAOD (28 with claudication, 11 with critical limb ischemia). Plasma viscosity was measured at 37°C using a capillary viscosimeter (AMV-200 Paar). In groups B and C, the mean TC was higher (7.4, 6.9 mmolil) than in the control group (5.6 mmoY1) (P < 0.01). HDL-C decreased with progression of PAOD and was lower in patients with critical limb ischemia than in controls. Patients with PAOD also had higher Tg than controls (2.8 vs 1.3 mmol/l, P =Z0.01). Fibrinogen concentration increased with clinical progression of PAOD and to a lesser extent with TC. Patients (groups B, C) were found to have mean plasma viscosity significantly higher (1.74, 1.78 mPa) than controls (1.64 mPa), with a non-significant tendency towards higher values with PAOD. In all groups plasma viscosity correlated with fibrinogen concentration (r = 0.70, P < 0.01) and to a lesser extent with TC (r = 0.52, P < 0.05). Multivariate analysis indicated that the cholesterol effect was independent, and accounted for 7% of the observed viscosity. In addition, plasma viscosity correlated negatively with HDL-C (r = 0.24, P c 0.05). We conclude that hyperlipoproteinemias are associated with alterations in blood rheology and that increased blood viscosity may be one of the mechanisms by which hypercholesterolemia could be atherogenic. Llsl m,
Hemorheological effects of captopril and nilvadipine in essential hypertension Izumi Y, Takahashi T, Satoh K, Ichihara S-I, Hosomi N,
Hemorheological disturbances am risk factors for cerebrovascular and ischemic heart diseases. Blood viscosity is significantly raised in patients with essential hypertension (EH). We investigated the hemorheological effects of captopril and nilvadipine on elevated blood viscosity in patients with EH. Hemorheological parameters were measured in 32 patients with EH (more than 160/95 mmHg BP), before and after treatment with 37.5/75.0 mg/day captopril, an angiotensin converting enzyme inhibitor (n = 19, mean 62.1 years) or with 8/12 mg/day nilvadipine, a Ca2+ antagonist (n = 13, mean 63.7 years), and in I5 elderly normals (mean 65.8 years). Whole blood and plasma viscosities, corrected blood viscosity at low shear rate (112.5 s-l) and high shear rate (225.0 s-l) and at standard hematocrit of 4546, hematocrit and serum albumin were measured before and after drug treatment. Viscosities were measured by cone-plate viscometer. BPS and whole and corrected blood viscosities, higher in patients with EH than in elderly normals before medication, (P < 0.001-0.01) decreased significantly after captoptil (P < 0.001-0.01) or nilvadipine (P < 0.05). Systolic BP correlated with corrected blood viscosity before and after captopril (r = 0.404, P c 0.01) or nilvadipine (r = 0.385, P < 0.05). Thus, either drug brought about significant reductions in BP and rheological parameters. Both drugs improve hemorheology as well as reducing BP in essential hypertension. 1161
Effects of lowering cholesterol by pravastatin on red blood cell aggregation in patients with occlusive cerebrovascular disease Haida M, Ogawa S, Hamano H, Ohsuga H, Shino-
mM. hara Y, Dept. of Neurology, Tokai Univ. Sch. of Med., Isehara, Kanagawa, 259-l I Japan
We investigated the effects of lowering serum cholesterol by pravastatin on red blood cell aggregation (RBC-A), a major hemorheological factor in patients with occlusive cerebrovascular
Atherosclerosis X, Montreal, October 1994
264
were similar in all genotypes. Subjects with E3 genotype had a lower dietary carbohydrate intake compared to E4 genotypes, but otherwise no significant differences were observed in dietary habits or in alcohol intake between different genotypes. Serum LDL-C was lower (P c 0.05) in men with the E2 genotype than in the E3 genotype. Median ape(a) level was significantly lower (P < 0.001) in the men with the Ecz genotype (95.5 U/l (57; 146)) than in the E3 genotype (178.5 U/l (144; 213)). As subjects with I?4 genotype may be at increased risk of CHD, the pnsent data could explain some of the discrepancies in reports of the role of ape(a) as a risk factor for atherosclerotic cardiovascular diseases. Determination of the fine specificity and molecular cloning of two monoclonal antibodies directed against the receptor-binding domain of human apolipoprotein E Raffdi, Rassart E, Weisgraber K, Innerarity T, Milne R, Lipo-
1
protein and Atherosclerosis Group, Univ. of Ottawa Heart Inst., 1053 Curling Ave., Ottawa, Ontario, Canada, KlY 4E9
The fine specificities of two monoclonal antibodies (mAbs) that sham a common epitope have been determined. mAbs lD7 and 2E8 which recognize the LDL receptor binding domain on human apo E have been found to share very similar fine specificities and
both am capable of displacing the LDL receptor from apo E. Substitutions in apo E that result in a loss of a positive charge at residues 142, 143, 145, 146 and 150 produce a decrease in the ability of the variant to bind to both antibodies and the receptor. However, apo E(Arg 136 + Ser) and apo E(Arg 158 + Cys) are defective with respect to LDL receptor binding but are indistinguishable from wild type apo E with respect to lD7 immunoreactivity. 2E8, on the other hand, shows a reduced reactivity apo E&g 158 + Cys) but normal binding to apo E(Arg 136 + Ser). As well, the introduction of proline residues at positions 144 and 152 decreases both antibody and receptor binding either by replacing a critical residue for binding or by disrupting apo E secondary or tertiary structure. The molecular clones of the light and heavy chains of both mAbs have been obtained and characterized in order to further define their respective binding specificities. Primary sequence analysis revealed that, although both light chains am similar, very little amino acid homology exists between the heavy chains. A striking pattern of four negatively charged amino acids present in the second complementarity determining region of the 2E8 heavy chain approximately aligns with acidic amino acids within the consensus sequence of the LDL receptor ligand binding domain. This could indicate that mAb 2E8 and the LDL receptor use a common mode of interaction with apo E.
RHEOLOGY AND HEMODYNAMICS
1 wP,
Effect of hypercholesterolemia on plasma viscosity %iek B, Univ. Clinical Centre, Trnovo Hospital of
Matsuo H, 2nd Dept. of Int. Med., Kagawa Med. Sch., 1750-I Ikenobe, Miki-cho, Kagawa 761-07, Japan
Internal Med., Ljubjljana, Slovenia
Increased concentration of plasma cholesterol may be atherogenic through affecting blood rheology. We have studied the relationship between plasma lipoproteins and plasma viscosity in healthy volunteers and in patients with peripheral arterial occlusive disease (PAOD). The study included a group (A) of 10 volunteers without risk factors for atherosclerosis or clinical evidence of PAOD; in group B were 15 patients with elevated plasma cholesterol (20% or more above normal value) and in group C were 39 patients with hypercholesterolemia and PAOD (28 with claudication, 11 with critical limb ischemia). Plasma viscosity was measured at 37°C using a capillary viscosimeter (AMV-200 Paar). In groups B and C, the mean TC was higher (7.4, 6.9 mmolil) than in the control group (5.6 mmoY1) (P < 0.01). HDL-C decreased with progression of PAOD and was lower in patients with critical limb ischemia than in controls. Patients with PAOD also had higher Tg than controls (2.8 vs 1.3 mmol/l, P =Z0.01). Fibrinogen concentration increased with clinical progression of PAOD and to a lesser extent with TC. Patients (groups B, C) were found to have mean plasma viscosity significantly higher (1.74, 1.78 mPa) than controls (1.64 mPa), with a non-significant tendency towards higher values with PAOD. In all groups plasma viscosity correlated with fibrinogen concentration (r = 0.70, P < 0.01) and to a lesser extent with TC (r = 0.52, P < 0.05). Multivariate analysis indicated that the cholesterol effect was independent, and accounted for 7% of the observed viscosity. In addition, plasma viscosity correlated negatively with HDL-C (r = 0.24, P c 0.05). We conclude that hyperlipoproteinemias are associated with alterations in blood rheology and that increased blood viscosity may be one of the mechanisms by which hypercholesterolemia could be atherogenic. Llsl m,
Hemorheological effects of captopril and nilvadipine in essential hypertension Izumi Y, Takahashi T, Satoh K, Ichihara S-I, Hosomi N,
Hemorheological disturbances am risk factors for cerebrovascular and ischemic heart diseases. Blood viscosity is significantly raised in patients with essential hypertension (EH). We investigated the hemorheological effects of captopril and nilvadipine on elevated blood viscosity in patients with EH. Hemorheological parameters were measured in 32 patients with EH (more than 160/95 mmHg BP), before and after treatment with 37.5/75.0 mg/day captopril, an angiotensin converting enzyme inhibitor (n = 19, mean 62.1 years) or with 8/12 mg/day nilvadipine, a Ca2+ antagonist (n = 13, mean 63.7 years), and in I5 elderly normals (mean 65.8 years). Whole blood and plasma viscosities, corrected blood viscosity at low shear rate (112.5 s-l) and high shear rate (225.0 s-l) and at standard hematocrit of 4546, hematocrit and serum albumin were measured before and after drug treatment. Viscosities were measured by cone-plate viscometer. BPS and whole and corrected blood viscosities, higher in patients with EH than in elderly normals before medication, (P < 0.001-0.01) decreased significantly after captoptil (P < 0.001-0.01) or nilvadipine (P < 0.05). Systolic BP correlated with corrected blood viscosity before and after captopril (r = 0.404, P c 0.01) or nilvadipine (r = 0.385, P < 0.05). Thus, either drug brought about significant reductions in BP and rheological parameters. Both drugs improve hemorheology as well as reducing BP in essential hypertension. 1161
Effects of lowering cholesterol by pravastatin on red blood cell aggregation in patients with occlusive cerebrovascular disease Haida M, Ogawa S, Hamano H, Ohsuga H, Shino-
mM. hara Y, Dept. of Neurology, Tokai Univ. Sch. of Med., Isehara, Kanagawa, 259-l I Japan
We investigated the effects of lowering serum cholesterol by pravastatin on red blood cell aggregation (RBC-A), a major hemorheological factor in patients with occlusive cerebrovascular
Atherosclerosis X, Montreal, October 1994