Utilization of calculated low density lipoprotein cholesterol and measured low density lipoprotein cholesterol in Siriraj Hospital.

A study to determine the utilization of calculated low density lipoprotein (c-LDL) cholesterol and measured low density lipoprotein (m-LDL) cholesterol was conducted. The test results of total cholesterol, triglyceride, HDL-cholesterol and m-LDL-cholesterol from the same individuals aged > or = 18 years who had the tests done at the Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital during January to December 2004 were retrieved. The c-LDL-cholesterol level was computed using Friedewald formula. There were two data sets i.e. the m-LDL-cholesterol cut-off level derivation data set (784 subjects) and the m-LDL-cholesterol cut-off level validation data set (800 subjects). The study results revealed: 1) 2.6% of the subjects had blood triglyceride > 400 mg/dl hence c-LDL-cholesterol could not be computed, 2) the correlation between c-LDL-cholesterol levels and m-LDL-cholesterol levels from both data sets was very good (r > 0. 95, p < 0. 001), 3) the m-LDL-cholesterol levels were usually higher than c-LDL-cholesterol levels, 4) the m-LDL-cholesterol cut-off level derivation data set showed that m-LDL-cholesterol < 87, > 143, > 188, > 233 and > 254 mg/dl were highly correlated with c-LDL-cholesterol < 100, > or = 100, > or = 130, > or = 160 and > or = 190 mg/dl respectively, 5) an application of m-LDL-cholesterol cut-off levels derived from the m-LDL-cholesterol cut-off level derivation data set to the m-LDL-cholesterol cut-off level validation data set showed that m-LDL-cholesterol < 87, > 143, > 188, > 233 and > 254 mg/dl had accuracy in predicting c-LDL-cholesterol < 100, > or = 100, > or = 130, > or = 160 and > or = 190 mg/dl of 100%, 99. 7%, 100%, 100% and 100% respectively, 6) the use of m-LDL-cholesterol levels as a guide for initiating lipid-lowering agents based on cut-off values of c-LDL-cholesterol levels led to an overuse of lipid-lowering agents in 3.6% to 42.9% of the patients and 7) Nomogram for transforming m-LDL-cholesterol to c-LDL-cholesterol was developed as well as a formula for transforming m-LDL-cholesterol to c-LDL-cholesterol (c-LDL-cholesterol = 0.89 x m-LDL-cholesterol). Therefore, m-LDL-cholesterol assay has a very limited use in managing individuals with suspected or known dyslipidemia. The use of m-LDL-cholesterol level as a guide for management of abnormal LDL-cholesterol conditions leads to an overuse of lipid lowering medications and an enormous expense of m-LDL-cholesterol assay.

Biochemical evidence of myocardial cell damage in heart failure : A canine model of cardiac injury.

The objective of the present study was to evaluate the diagnostic efficiency of the new cardiac-specific marker troponin T (cTnT) compared with the conventional markers creatine kinase (CK) and lactate dehydrogenase (LDH) in detecting myocardial injury in dogs with clinical signs and symptoms of various forms of cardiac diseases including congestive heart failure (CHF). The results showed that in animals with clinical valvular heart disease (n = 20), clinical cardiac arrhythmias (n = 11) and heartworm infection (n = 10) without clinical heart failure, as well as in dogs with clinical CHF (n = 18), there was no significant difference either in the activity of CK or LDH. Levels of cTnT in dogs with CHF, on the other hand, were much higher than those in the other 3 groups. The majority of the 18 dogs with CHF had detectable levels of cTnT, with 6 of them (33%) showing values exceeding the upper reference limit of 0.10 ng/ml. The overall mean cTnT level in this animal group was 0.204 ng/ml. These results may imply that CHF in dogs is associated with a small release of cardiac troponin T indicative of minor myocardial cell damage.

Association between non-high-density lipoprotein and apolipoprotein B-containing lipoproteins.

Accurate measurements of low-density lipoprotein (LDL) cholesterol are essential in the management of patients with atherosclerotic cardiovascular disease. Since the conventional method of calculating LDL cholesterol by the Friedewald equation has several methodological limitations, the use of a novel and simple method for estimation of non-high-density lipoprotein (non-HDL) cholesterol concentration was recently proposed as a tool for assessing cardiovascular risk. In the present study, the associations of non-HDL cholesterol with apolipoprotein B-containing lipoproteins [LDL and lipoprotein (a)] and other lipid parameters were examined in 103 middle-aged apparently healthy individuals. The results revealed a strong correlation between levels of non-HDL cholesterol and those of total cholesterol (r = 0.942), LDL cholesterol (r = 0.943) and total cholesterol : HDL cholesterol ratio (r = 0.744). Similarly high correlation coefficients were obtained from individuals with triglyceride levels of more than 140 mg/dl (n = 35). In contrast to LDL cholesterol, non-HDL cholesterol also showed significant correlations with triglycerides and HDL cholesterol in the total study population. Levels of lipoprotein (a), on the other hand, did not exhibit association with any of the lipid and lipoprotein variables measured in this study. In conclusion, non-HDL cholesterol may provide a surrogate for calculated LDL cholesterol in assessing the risk of cardiovascular disease, particularly in individuals with high triglyceride levels.

Assessment of radiofrequency current-induced myocardial damage based on analysis of cardiac troponin T serum concentration.

The present study investigated the effect of radiofrequency (RF) current energy energy on the release pattern of myocardial marker proteins in 44 patients undergoing RF catheter ablation of supraventricular and ventricular tachycardia serial measurements of the activity of enzyme creatine kinase (enzymatic method), CK-MB isoneration TnT Enzymum ELISA, Boehringer Mannheim). The results showed that nearly all (91 percent) of the patients studied demonstrated a significant elevation in cTnT concentration following transcatheter applications of RF energy, whereas only 12 (27 percent) and 13 (29 percent) patients exhibited a postprocedural increase in CK and CK-MB activity, respectively. In contrast to the variable time for peak activity of CK and CK-MB, 40 of the 44 patients displayed an early peak cTnT concentration at eight hours after the procedure with a subsequent decline thereafter. Levels of cTnT and, to a lesser extent, CK but not CK-MB activity corressory pathways or atrioventricular nodal reentrant tachycardia. In conclusion, cardiac troponin T is a more sensitive indicator of RF energy-induced myocardial injury and has a more uniform pattern of myocardial release than the conventional CK and CK-MB. Determinations of cTnT serum concentration may thus provide a reliable method for assessing the extent of myocardial damage and for monitoring complications developed after radiofrequency or other froms of treascatheter ablation procedures.

Cyclosporine monitoring in patients with renal, cardiac and bone marrow transplants: A comparison between clone enzyme donor immunoassay and fluorescence polarization immunoassay methods.

In the present study a new method for selectively determining parent cyclosporine in whole blood, a clone enzyme donor immunoassay (CEDIA; Boehringer Mannheim), was compared with a fluorescence polarization immunoassay (FPIA; TDxAbbott). A total of 429 samples were collected, comprising 371 renal, 34 cardiac, 14 bone marrow and 10 corneal transplant recipients. Regression equations in 429 samples is CEDIA cyclosporine (ng/mL) = 0.999 x FPIA (ng/mL) + 1.684, (r=0.997). The linearity analysis was done from 0 – 1,000 ng/mL, which gave a good analytical range of between 15-600 ng/mL. The new CEDIA method also has within-rin CV = 1.77 – 3.69 percent which is better than the FPIA method (2.20 – 6.10 percent). The advantages of the new CEDIA method are the lower cost of the reagents and the fact that there is no need to purchase a new automated clinical chemistry analyser since it can be applied to routine chemistry instruments immediately after the reagents become available to the laboratory.

Glucose dehydrogenase biosensor for glucose monitoring: An accurate oxygen-insensitive electrochemical biosensor.

In severely hypotensive patients, fingerstick glucose determinations often do not accurately represent venous glucose levels. Those fingerstick glucose values that fall outside the acceptable range in hypotensive patient group are all lowere than the standard glucose values because the strip used is the oxygen-sensitive glucose oxidase method. This condition will be incorrectly diagnosed as a hypoglycaemic condition instead of normal. The objective of this study was to evaluate the O2-insensitivity of a new electrochemical biosensor test strip that can be used for different types of blood samples. This biosensor uses an O2-independent glucose dehydrogenase enzyme instead of an O2-dependent glucose oxidase enzyme in the reaction. We compared glucose measurements between venous blood by biosensor with the standard method which gave a coefficient of correlation (r)=0.998 (n=216). In cases of arterial blood with a wide range of pO2 varying from 21.7 mmHg to 388.7 mmHg, we compared the glucose levels measured by biosensor with standard method which gave r=0.997 (n=148). The precision analysis was tested in three glucose levels and gave a coefficient of variation (CV) less than 3 percent. The results showed that the new electrochemical biosensor was oxygen-insensitive and provided rapid, precise and accurate glucose measurements.

Analytical performance of direct LDL-cholesterol assay compared with friedewald LDL-cholesterol and apolipoprotein B assay.

Clinical laboratory currently estimate low-density lipoprotein cholesterol using the Friedewald formula, which requires fasting specimens and is subject to error with increasing triglyceride levels. The direct LDL Immunoseperation Reagent for LDL-cholesterol assay also have some disadvantages: 1. pipetting sample, 2. mixing and 3. centrifugation before subsequent measurement of cholesterol by conventional assay. We describe a rapid non-percipitating LDL-cholester assay using tentaclepolynion (PAMPS) reagent which base on precision with within-run and run-to-run coefficients of variation less than 3%. Results are in good agreement with the apolipoprotein assay (direct LDL-C = 1.745 apolipoprotein B-49.764 mg/dL, r=0.805) and also show very good linear regression with Friedewald LDL-C which triglyceride level below 400 mg/dL (Friedewald LDL-C=0.978 direct LDL-C-1.616 mg/dL, r=0.968). This method overcomes drawbacks the Friedewald formula and appears to be useful tool in managing hyperlipidemic patients by using an accurate quantification of LDl-C in the routine laboratory.

Lipoprotein and apolipoprotein profile in children with primary nephrotic syndrome: Metabolic alterations and consequences.

Serum levels of lipoprotein and apolipoprotein from 50 children, aged between 2 and 16 years, were measured by the enzymatic method and by immunoturbidimetric assay respectively, to determine abnormalities of lipid metabolism during the course of primary nephritic syndrome. There was a highly significant correlation between serum levels of both total cholesterol and low density lipoprotein cholesterol (LDL-C) and those of apolipoprotein B (apo B) (n=114, r=0.946, p<0.001 and n=99, r=0.943, p<0.001, respectively) and, to a lesser extent, between serum high density lipoprotein cholesterol (HDL-C) and apolipoprotein A-I (apo A-I) levels (n=123, r=0.679, p<0.001). HDL-C levels of apo A-I did not exhibit an association with those of albumin. The ratio of HDL-C to apo A-I, on the other hand, was low (<1.0) at very low levels of serum albumin (<2.0 g/dI) but showed a gradual rise with increasing albumin levels. These results may indicate a compositional change in HDL particles in the clinical course of nephritic syndrome, with a relatively high level of apolipoprotein-rich HDL particle (HDL)3 at very low albumin levels and predominantly HDL2 particles, which contain relatively more cholesterol, at increasing levels of albumin. Serum levels of LDL-C and apo B correlated significantly and inversely with serum albumin levels (n=101, r=-0.836, p<0.001 and n=114, r=-0.825, p<0.001, respectively). Compared with levels from healthy control children (2.52+0.67 mmol/L (97+26 mg/dI) and 0.86+0.21 g/L) matched for age and serum albumin levels, however, a relatively high concentration of both parameters of 3.59+1.02 mmol/L (139+40 mg/dI) and 1.47+0.32 g/L, respectively, was still observed at high serum albumin levels (> 4 g/dI). The finding of a persistance of abnormalities in lipid profile, despite a response to treatment of nephritic syndrome, may have some prognostic significance and should been given therapeutic consideration in the long-term management of children with primary nephrotic syndrome.

Direct measurement of high-density lipoprotein cholesterol compared with the precipitation-based methods.

We compared the performance of the direct measurement for quantifying high-density lipoprotein cholesterol (HDL-C) with the precipitation-based method for HDL-C, using samples with a wide range of HDL-C concentrations (7-144 mg/dL). The coefficient of correlation for the two methods was 0.98 (n=500). Both methods were precise with a run-to-rum CV of < 4.4 per cent. By using direct measurement for HDL-C we can reduce errors which occurred in the precipitation-based method, especially from centrifugation and recovery of the supernatant. The direct measurement method strongly appears to successfully discriminate between the serum HDL fractions and completely measures the HDL-C.

Sterility and storage period of placental blood from neonates delivered by caesarian section.

A prospective study was conducted to evaluate the storage period and sterility of placental blood from neonates delivered by caesarian section. Following caesarian section of the infant and placenta, the placenta was immediately placed in a sterile tray and the umbilical cord near the clamps was rinsed with sterile saline and cut 2 cm below the clamps with sterile scissors. An Fr 8 feeding tube was inserted into an umbilical vein and 43 ml of placental blood was drawn into a 50 ml disposable syringe which contained 7 mls of CPDA-1 solution. Five-ml aliquots of blood retrieved from the placenta were inoculated into aerobic and anaerobic blood culture bottles. Sixty-four specimens of CODA-1 anticoagulant blood were retrieved from the placenta and evaluated for biochemical changes to determine the recommended storage period. The mean plasma potassium concentrations were 4.9 + 1.1, 9.1 + 2.6, 13.1 + 2.0 mM/l at 0, 48 and 72 hours after collection, respectively. The 72-hour potassium concentration was higher than the value in adult whole blood stored for 7 days, which is considered fresh blood and recommended for transfusing newborn infants. The 107 paired aerobic/anaerobic culture specimens showed an overall contamination rate of 13%. These findungs suggest that placental blood in CPDA-1 can be stored for 48 hours for autologous transfusion and that rinsing the umbilical cord in sterile saline cannot prevent bacterial contamination in the retrieved placental blood.