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Apolipoprotein E2, isoforms of different mobility: A novel cause of type III hyperlipoproteinaemia
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USE OF SODIUM DODECYL SULPHATE FOR THE SELECTIVE ASSASY OF LPL IN PHP SAMPLES: VALIDATION OF HL’S SELECTIVE INHIBITION BY COMPARISON WITH LPL ACITVITIES OBTAINED USING HL ANTISERUM. Henderson AD, Richmond W; Elk&s RS Unit of Metabolic Medicine. St Mary’s Hospital. F’raed Street. London W2 1PG Post hcparin plasma (PHP) conbins at least 2 enzymes catalysing the hydrolysis of lipoprotein triglyceride namely, Lipoprotein lipase (LPL) and Hcpatic lipase (HL). Selective assay of either enzyme requires the absence of the other activity. LPL’s inactivation by 1 mol/l N&l facilitates selective asay of HL. LPL may bc estimated as the difference between total lipolytic activity (i.e. PHPLA) and HL activity. Selective assay of LPL may be achieved by pretreating the PHP sample wi& an antiserum to HL.An alternative approach may be offered by Sodium dodecyl sulphate (SDS), reputed to selectively inacGvatc HL (1’).
We have evaluatedtheSDS approachbycomparing LPLactivities detectable in15PHPsamples after inactivationof HL by (x)goat antiserum tohuman HL and (y) 35 mmol/l SDS. The results cormlate (r’=0.84) around a linear regression line y=O.96x + 1.70, the small increase in LPL activity observed with the SDS procedure being attributable lo the surfactant’s effect on the substrate, a radiolabelled niolein emulsion. Using the SDS procedure we have quantified LPL activity in PHP samples from 32 normal individuals, and found a significant sex diffcrancc (p
APOLIPDPROTeIN R ISOFO~S OF DIFFERENT MOBILITY: A NDVEL CAUSE OF Typg III HYPERLIPoPRo!rEINAEHLA.
D. Wile, S. Niththyananthan, I. Trayner, A.K. Soutar and G.R. Thompson MRC Lipoprotein Team and Department of Chemical Pathology, HanunersmithHospital, London A 41 year-old man from Grenada presented with a 1 year history of tubero-eruptive xanthomata. Investigation revealed serum total cholesterol 11.9, triglyceride 10.4 rmnol/land a broad 8 band on lipoprotein electrophoresis. He had remained well and was euthyroid on replacement therapy since pituitary ablation 15 years previously. Isoelectric focussing revealed two bands of equal intensity in the apoE, region, each persistent despite neuraminidase and reactive with monoclonal anti-apoE on inununoblotting. Cysteamine treatment increased the mobility of both bands but differentially.These findings imply compound heterozygosity for two different apoE, alleles, each containing 2 cysteine residues, one isofonn is probably the common Arg,,, + cys version of apoEz. Family studies and direct sequencing of part of the gene are now in progress to ascertain the nature of this and of the other, possibly unique, defect.
VABCULAR RISK FACTORS IN CORONARY HEART DISEASE (CHD) ASSOCIATED WITH TYPE 1 DIABETES tiELLI+US. PH Winocour, PN Durrington, D Bhatnagar, A Mbewu, M Ishola, M Mackness and S Arrol. University of Manchester Department of Medicine. The contribution of lipoproteins, fibrinogen, blood pressure and albuminuria to CHD was examined in SO individuals with insulin-dependent diabetes mellitus (IDDM). Those 23 with CHD had significantly higher levels of systolic blood pressure (160(4) (mean v 142(2( mmHg, p200 mu/l was comparable in those with or without CHD. Regression analysis revealed the strongest independent predictors of CHD were serum triglycerides (r 0.20), followed by systolic blood pressure (r 0.301, ate (r 0.33) and total serum cholesterol (r d.38), multip’le correlation coefficient 0.62. CHrf in IDDM appears to be most closely associated with increasing age and levels of blood pressure and serum lipids. AER, apolipoprotein and fibrinogen concentrations do not appear to be m determinants of CHD in IDDM.
THEEFFECTOFDIET ALONE OR DIETPLUSSULPUOYYLlJRBAS IWNBWLY PRESEUTIWC, NOU-INSULIN DKPMDMT DIABBTBS HELLITIJS (NIDDHI PATIENTS
D.R. Owens,S. Yilliass, J. Dean, J. Dolben, S. Luzio and A. Hir. Diabetes ResearchUnit, UYCH, Heath Park, Cardiff. 127 newly presenting previously untreated NIDDHpatient8 uere studied. Following an initial 3 month dietary period the patients were allocated to continue on diet lDTlalone (a = 66) or to receive in addition an oral hypoglycaeaic IOHA sulphonylureal agent In = 611based on a fasting plasmaglucose level belowor above 9 1101/l respectively. Pre-treatment the DT and OBApatient groups differed according to body lass index IBIII): 29.8 vs 26.5 p ( 0.001; fasting plasmaglucose Imol/ll Il.2 vs 13.2 p ( 0.01; HbAt1%) 10.4 vs 12.1 p ( 0.001; urea imolll) 5.0 vs 5.6 p ( 0.05, respectively. The mean(t SD)at presentation cholesterol uas 5.34 Il.21 1101/l, uith 10.9 \ and 43.91 of patients 16.5 and j5.2 mol/l respectively. After 12 ronths treatneat, the fasting plasmaglucose IPPGIand BbAlin the DT and OHAgroups were 8.3, 8.2 1101/l and 8.3, 8.5% respectively. DT alone achieved a non-significant fall in total cholesterol: 5.35 vs 5.14: and total triglycerides: 2.29 vs 2.01 with little changein HDL-cholesterol:1.10 vs 1.13. Diet plus sulphonylureas resulted in a significant fall in total cholesterol: 5.33 vs 4.93, p ( 0.01, and total triglycerides : 1.91 vs 1.77, with a further reduction in HDL-cholesterol:1.09 to 1.03. Successful dietary treatneat can reduce total cholesterol and increase BDL-cholesterol levels, uhereas sulphonylureatreatlent further lowers HDL-cholesterol.
USE OF SODIUM DODECYL SULPHATE FOR THE SELECTIVE ASSASY OF LPL IN PHP SAMPLES: VALIDATION OF HL’S SELECTIVE INHIBITION BY COMPARISON WITH LPL ACITVITIES OBTAINED USING HL ANTISERUM. Henderson AD, Richmond W; Elk&s RS Unit of Metabolic Medicine. St Mary’s Hospital. F’raed Street. London W2 1PG Post hcparin plasma (PHP) conbins at least 2 enzymes catalysing the hydrolysis of lipoprotein triglyceride namely, Lipoprotein lipase (LPL) and Hcpatic lipase (HL). Selective assay of either enzyme requires the absence of the other activity. LPL’s inactivation by 1 mol/l N&l facilitates selective asay of HL. LPL may bc estimated as the difference between total lipolytic activity (i.e. PHPLA) and HL activity. Selective assay of LPL may be achieved by pretreating the PHP sample wi& an antiserum to HL.An alternative approach may be offered by Sodium dodecyl sulphate (SDS), reputed to selectively inacGvatc HL (1’).
We have evaluatedtheSDS approachbycomparing LPLactivities detectable in15PHPsamples after inactivationof HL by (x)goat antiserum tohuman HL and (y) 35 mmol/l SDS. The results cormlate (r’=0.84) around a linear regression line y=O.96x + 1.70, the small increase in LPL activity observed with the SDS procedure being attributable lo the surfactant’s effect on the substrate, a radiolabelled niolein emulsion. Using the SDS procedure we have quantified LPL activity in PHP samples from 32 normal individuals, and found a significant sex diffcrancc (p
APOLIPDPROTeIN R ISOFO~S OF DIFFERENT MOBILITY: A NDVEL CAUSE OF Typg III HYPERLIPoPRo!rEINAEHLA.
D. Wile, S. Niththyananthan, I. Trayner, A.K. Soutar and G.R. Thompson MRC Lipoprotein Team and Department of Chemical Pathology, HanunersmithHospital, London A 41 year-old man from Grenada presented with a 1 year history of tubero-eruptive xanthomata. Investigation revealed serum total cholesterol 11.9, triglyceride 10.4 rmnol/land a broad 8 band on lipoprotein electrophoresis. He had remained well and was euthyroid on replacement therapy since pituitary ablation 15 years previously. Isoelectric focussing revealed two bands of equal intensity in the apoE, region, each persistent despite neuraminidase and reactive with monoclonal anti-apoE on inununoblotting. Cysteamine treatment increased the mobility of both bands but differentially.These findings imply compound heterozygosity for two different apoE, alleles, each containing 2 cysteine residues, one isofonn is probably the common Arg,,, + cys version of apoEz. Family studies and direct sequencing of part of the gene are now in progress to ascertain the nature of this and of the other, possibly unique, defect.
VABCULAR RISK FACTORS IN CORONARY HEART DISEASE (CHD) ASSOCIATED WITH TYPE 1 DIABETES tiELLI+US. PH Winocour, PN Durrington, D Bhatnagar, A Mbewu, M Ishola, M Mackness and S Arrol. University of Manchester Department of Medicine. The contribution of lipoproteins, fibrinogen, blood pressure and albuminuria to CHD was examined in SO individuals with insulin-dependent diabetes mellitus (IDDM). Those 23 with CHD had significantly higher levels of systolic blood pressure (160(4) (mean v 142(2( mmHg, p
THEEFFECTOFDIET ALONE OR DIETPLUSSULPUOYYLlJRBAS IWNBWLY PRESEUTIWC, NOU-INSULIN DKPMDMT DIABBTBS HELLITIJS (NIDDHI PATIENTS
D.R. Owens,S. Yilliass, J. Dean, J. Dolben, S. Luzio and A. Hir. Diabetes ResearchUnit, UYCH, Heath Park, Cardiff. 127 newly presenting previously untreated NIDDHpatient8 uere studied. Following an initial 3 month dietary period the patients were allocated to continue on diet lDTlalone (a = 66) or to receive in addition an oral hypoglycaeaic IOHA sulphonylureal agent In = 611based on a fasting plasmaglucose level belowor above 9 1101/l respectively. Pre-treatment the DT and OBApatient groups differed according to body lass index IBIII): 29.8 vs 26.5 p ( 0.001; fasting plasmaglucose Imol/ll Il.2 vs 13.2 p ( 0.01; HbAt1%) 10.4 vs 12.1 p ( 0.001; urea imolll) 5.0 vs 5.6 p ( 0.05, respectively. The mean(t SD)at presentation cholesterol uas 5.34 Il.21 1101/l, uith 10.9 \ and 43.91 of patients 16.5 and j5.2 mol/l respectively. After 12 ronths treatneat, the fasting plasmaglucose IPPGIand BbAlin the DT and OHAgroups were 8.3, 8.2 1101/l and 8.3, 8.5% respectively. DT alone achieved a non-significant fall in total cholesterol: 5.35 vs 5.14: and total triglycerides: 2.29 vs 2.01 with little changein HDL-cholesterol:1.10 vs 1.13. Diet plus sulphonylureas resulted in a significant fall in total cholesterol: 5.33 vs 4.93, p ( 0.01, and total triglycerides : 1.91 vs 1.77, with a further reduction in HDL-cholesterol:1.09 to 1.03. Successful dietary treatneat can reduce total cholesterol and increase BDL-cholesterol levels, uhereas sulphonylureatreatlent further lowers HDL-cholesterol.