Determination Of Total Cholesterol In Serum Research Articles

Lipid profile and pregnancy associated pathologies

Throughout pregnancy, maternal lipid metabolism changes substantially, all of which can be seen by analysing the lipid profile. Determination of serum total cholesterol, triglyceride, high-density lipoprotein cholesterol and low-density lipoprotein cholesterol levels may have a predictive role in the subsequent development of pregnancyspecific pathologies such as preeclampsia, intrahepatic cholestasis of pregnancy and gestational diabetes. Also, disorders present in the lipid profile may influence the weight of the newborn at birth. Early dyslipidaemia during pregnancy, manifested by elevated triglycerides and low-density lipoprotein cholesterol serum levels, has been associated with the development of preeclampsia. In laboratory tests, pregnant women diagnosed with intrahepatic cholestasis have significantly higher plasma triglycerides levels and reduced high-density lipoprotein cholesterol concentrations compared to healthy pregnant women. In case of foetal intrauterine growth restriction in the newborn, literature data report significantly increased triglycerides levels. Women who during pregnancy developed gestational diabetes had higher plasma triglycerides levels and lower high-density lipoprotein cholesterol levels, with no statistically significant difference between serum triglycerides or high-density lipoprotein cholesterol levels.

ANTI-DIABETIC EFFECTS OF ETHANOL LEAF EXTRACT OF ONIONS (Allium cepa) ON ALLOXAN-INDUCED DIABETIC WISTAR ALBINO RATS

ANTI-DIABETIC EFFECTS OF ETHANOL LEAF EXTRACT OF ONIONS (Allium cepa) ON ALLOXAN-INDUCED DIABETIC WISTAR ALBINO RATS

Change of antioxidant protection indicators in patients with osteoarthritis in the course of the treatment with a combined chondroprotective drug

Objective of the study. The study of changes in some parameters of the lipid peroxidation system - antioxidant protection, lipid spectrum in the course of the long-term therapy with the combined chondroprotective drug ARTRA in patients with knee osteoarthritis (OA) Methods. 24 patients with osteoarthritis of the knee joints with 1-3 X-ray stage of the disease (Kellgren and Lawrence, 1957) at the age of 41.8 ± 6.1 years were included in an open prospective study to evaluate the effects of CCD. The following indicators in serum and erythrocytes were determined: initial products of LPO (diene conjugates (DC), ketodienes and conjugated trienes (KD and CT)) in the heptane and isopropanol phase (the method of I.A. Volchegorsky, et al, 1989); intermediates (thiobarbituric acid test modified by L.I. Andreeva, et al, 1988); catalase activity (the method of M.A. Korolyuk et al., 1988); antioxidant activity of plasma (the method of M. Promyslov, 1990); peroxide erythrocyte resistance (G.A. Yarovaya, 1987). The quantitative determination of serum total cholesterol, low-density, very-low-density, high-density lipoprotein cholesterol, triglycerides was carried out using the ready-made CORMEY standardized sets (Germany). The patients’ condition and laboratory parameters were evaluated before the study, in 12 and 24 weeks after CCD was taken. Changes in the examined indicators were documented after a 24-week course. The inhibition of lipid peroxidation processes in the form of a decrease in the primary products and intermediates in the serum and erythrocytes was established. The study showed an increase in antioxidant protection (increased activity of blood serum catalase and erythrocytes and total antioxidant activity of blood serum). The patients’ tests showed a decrease in the concentration of total cholesterol and cholesterols of low-density lipoproteins. Conclusion. The study demonstrated the positive impact of ARTRA on the LPO-antioxidant protection system and the lipid spectrum in patients with OA following the 24-week administration.

Biochemical effect of resveratrol on Lipids profile and hepatic oxidative stress in experimentally induced obesity in female rats

This study was designed to evaluate the effect of prolonged intake of resveratrol on lipid metabolism, liver enzymes andL-malondialdehyde(L-MDA) in obesity -induced in female rats by feeding high fat diet. Ninety female albino rats weredivided into six equal groups of 15 rats each. Group Ι: rats fed normal control diet all over the periods of experiment (for12 weeks). Group II: rats fed the control normal diet and administered resveratrol orally (0.1 mg/kg b.wt., orally) for 6weeks. Group III: rats received the control normal diet and received resveratrol once daily (0.5 mg/kg b.wt., orally) for 6weeks. Group IV: rats fed high fat diet (HFD) and received no drugs all over the periods of experiment (for 12 weeks).Group V: rats received HFD and administered resveratrol (0.1 mg/kg b.wt./day, orally) for 6 weeks. Group VI: rats fedHFD and administered resveratrol (0.5 mg/kg b.wt./day, orally). Blood samples were collected from all rats at 2, 4 and 6weeks from the onset of resveratrol administration for determination of serum total cholesterol(TC), Triacylglycerols(TAG), high density lipoprotein cholesterol (HDL-c), low density lipoprotein cholesterol (LDL-c), very low densitylipoprotein cholesterol (VLDL-c), alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkalinephosphatase (ALP), and erythrocyte L-malondialdehyde (L-MDA).The obtained results showed, significant elevation ofserum TC, TAG, LDL-c, VLDL-c, ALP,AST, ALT, L-MDA in obese rats as compared to rats fed normal control diet.While administration of resveratrol to HFD-fed rats tended to improve hepatic oxidative stress and dyslipidemia throughimproving total cholesterol and triacylglycerols and liver markers enzyme activities. These results suggest that, resveratrolis effective in improving the obesity and its associated many important complications such as diabetes mellitus andcoronary heart disease and liver disease

Amperometric determination of serum total cholesterol with nanoparticles of cholesterol esterase and cholesterol oxidase

We describe the preparation of glutaraldehyde cross-linked and functionalized cholesterol esterase nanoparticles (ChENPs) and cholesterol oxidase nanoparticles (ChOxNPs) aggregates and their co-immobilization onto Au electrode for improved amperometric determination of serum total cholesterol. Transmission electron microscope (TEM) images of ChENPs and ChOxNPs showed their spherical shape and average size of 35.40 and 56.97 nm, respectively. Scanning electron microscope (SEM) studies of Au electrode confirmed the co-immobilization of enzyme nanoparticles (ENPs). The biosensor exhibited optimal response at pH 5.5 and 40 °C within 5 s when polarized at +0.25 V versus Ag/AgCl. The working/linear range of the biosensor was 10–700 mg/dl for cholesterol. The sensor showed high sensitivity and measured total cholesterol as low as 0.1 mg/dl. The biosensor was evaluated and employed for total cholesterol determination in sera of apparently healthy and diseased persons. The analytical recovery of added cholesterol was 90%, whereas the within-batch and between-batch coefficients of variation (CVs) were less than 2% and less than 3%. There was a good correlation (r = 0.99) between serum cholesterol values as measured by the standard enzymic colorimetric method and the current method. The initial activity of ENPs/working electrode was reduced by 50% during its regular use (200 times) over a period of 60 days when stored dry at 4 °C.

EFFECT OF POMEGRANATE PEEL ON THE BLOOD LIPID PROFILE OF EXPERIMENTAL RATS

EFFECT OF POMEGRANATE PEEL ON THE BLOOD LIPID PROFILE OF EXPERIMENTAL RATS This study was carried to investigate the effects of pomegranate peels(Punic granatumL), on the blood lipid level, some physiological parameters as liver function, kidney function, histological properties of Heart in hypercholestrmic. Rats were divided into 2 groups first group as negative group and the second group thypercholestrmic group which divided into 4 groups positive control, and 3 thypercholestrmic groups, fed on several diets containing 5%, 10%,15% of pomegranate peels for 28 days. Peel was cleaned from impurities and washed with tap water. Drying Oven air dry at 45 °C was used for 48 hours to dry the peel, then ground in a Multi Mill apparatus to passe through a 50 mesh sieve to obtain a fine peel powder . Bodyweight gain, feed intake and feed efficiency ratio were calculated at the end of experiment. Fasting blood sample were taken on day 28 for the determination of serum total cholesterol (TC) , serum triglycerides (TG) , HDL cholesterol,LDL cholesterol ,creatinine, serum urea, aspartate aminotransferase (AST) and glutamic pyruvic transaminase (GPT). The heart of all animals were carefully removed and slices from them were fixed in 85% alcohol for 24 hours, and then processed for paraffin embedding. Histological sections, 7 micron-thick, were cut and stained with heamatoxylin and eosin. They were then microscopically examined to evaluate the effects of the three differ concentration of formalin on these organs. It was concluded that treatment using pomegranate peel (Punic granatum L), reduced significantly LDL-c ,Serum triglycerides in hypercholestremic rats which fed different levels of pomegranate peel and the decrease was the best as the level of supplement peels increased. تأثير قشور الرمان علي مستوي دهون الدم لفئران التجارب *وفائي زکي عازر ميخائيل،* حسن محمد صبحي، ** سحر عبد العزيز خيري، ** ماجدة رمزي قسطندي، ** علا علي علي قسم الإحتياجات الغذائية والنمو- المعهد القومى للتغذية- القاهرة** *معهد البحوث الافريقية قسم الموارد الطبيعية ،جامعة القاهرة يهدف هذا البحث إلى إمکانية إستخدام بعض مخلفات الثمار مثل قشور الرمان لإعداد وجبات غنية بالألياف عن طريق إضافتها بنسبة 5% ،10%، 15 % من القشور. فى هذة التجربة تم تقسيم الفئران إلى خمسة مجموعات المجموعة الأولى هى الکنترول السالب والأربع مجموعات الأخرى فتم إصابتها بإرتفاع الکوليتسرول وذلک بتغذيتها على 1,5% کوليسترول لمدة أسبوعين وترکت إحداهما کمجموعة ضابطة موجبة والثلاث مجموعات الأخرى تم إضافة مسحوق قشور الرمان (بعد تنظيفها بالماء وتجفيفها على درجة حرارة 45م لمدة 48 ساعة وطحنها) بنسب 5%، 10%، 15% وتم تغذية الفئران على الوجبات لمدة 28 يوم .فى نهاية التجربة تم ذبح الفئران وقياس مستوى الدهون في الدم والجليسريدات الثلاثية (TG) والکوليسترول HDLC, ووظائف الکلى والکبد وإجراء الفحص الهستولوباثولوجى للقلب. أوضحت النتائج انخفاض وزن الفئران عند تغذيتهم على القشور ولوحظ أيضا أن الالياف الموجودة فى القشور ادت الى انخفاض مستوى کلا من الکوليسترول الکلى والجليسريدات الثلاثية. وقد وجد ان تناول النسب العالية من القشور تؤدى إلى نتائج أفضل . الکلمات الکاشفة :- قشور الرمان - الکوليسترول- تراي جليسريد- وظائف الکلى- وظائف الکبد

49 Influence of oat β-glucan on postprandial glycemic and insulinemic responses to a meal or oral sugar

s / Journal of Equine Veterinary Science 35 (2015) 400e417 405 49 Influence of oat b-glucan on postprandial glycemic and insulinemic responses to a meal or oral sugar J. Weir*, V. Robbins, J.M. Bobel, L.A. Skurupey, and L.K. Warren University of Florida, Gainesville, FL, USA Oats are a favored cereal grain in equine rations and are rich in b-glucan (BG). This soluble fiber has been linked to health benefits in humans, including lowered cholesterol and postprandial glucose and insulin. We hypothesized that oat BG would yield similar benefits in horses. Eight mature, clinically healthy Quarter Horses (mean ± SEM, 569 ± 2 kg) were used in a 4 X 4 Latin square design study to determine the effect of oat BG on glycemic and insulinemic responses. Horses were fed 4 diets differing in amount and source of BG for 22 d: cracked corn (low BG control), regular feed oats (moderate BG), a highBG oat variety (high BG), or corn top-dressed with a concentrated oat BG powder (high BG). Both high BG diets provided 170 mg BG/kg BW/d. All diets were isocaloric. Horses also had free access to pasture forage and were fed a vitamin/mineral supplement. In each of 4 periods, 2 horses were fed each diet. Blood samples were obtained on d 0 and 21 for determination of serum total cholesterol. On d 21, glycemic and insulinemic responses to the assigned treatment diet were evaluated after an 8-h fast. Meal size was standardized to provide 0.8 g NSC/kg BW (an amount equal to the habitual meal size for both oat diets, but a lowered meal size for diets containing corn). On d 22, glycemic and insulinemic responses to an oral dose of sugar (corn syrup, 0.15 mL/kg BW) were evaluated after an 8-h fast. At the completion of each 22-d period, horses underwent a 13-d dietary washout (corn control diet), followed by reallocation of treatments. Data were compared using mixed model ANOVA with repeated measures. Serum cholesterol was not affected by diet and averaged 75.2 ± 1.6 mg/dL. Time to consume the meal differed between diets (P < 0.0001), averaging 13.4 and 7.5 min for diets containing oats and corn, respectively. Insulin response to a meal was affected by diet (P < 0.0001), time (P < 0.0001) and diet time (P < 0.0001), where serum insulin was higher and remained elevated longer in response to meals containing oats (regular or high BG) compared with the 2 diets containing corn. In response to the oral sugar test, insulin was affected by time (P < 0.0001) and diet time (P 1⁄4 0.027), with a lower response in the 2 diets containing a high level of BG compared with the corn and regular oat diets. Diet did not affect glycemic responses to either the meal or the oral sugar test. Results of the meal test likely reflect differences in foregut starch availability between oats and corn. However, responses to the oral sugar test suggest that habituation to diets containing a high level of oat BG may reduce the magnitude of insulin response.

Plasminogen activator inhibitor-1 in children with central obesity: Effect on left ventricular function

Aim The aim of the study was to investigate the Plasminogen activator inhibitor-1 (PAI-1) expression in obese children and to clarify its role with respect to left ventricular (LV) function. Patients and methods This study included 69 obese children and adolescents, 40 lean healthy controls. Children were considered obese according to body mass index (BMI) percentile for age and sex curves of growth for our population. Each subject’s fat distribution was assessed by measuring waist hip ratio (WHR). Obese children with peripheral fat distribution were excluded. Exclusion criteria included hypertension, endocrine, cardiovascular, renal, insulin dependent or independent diabetes mellitus and smoking habits. Laboratory investigations included measurement of plasma PAI-1 antigen. Determination of total serum cholesterol, low density lipoprotein, high density lipoprotein, triglycerides, blood glucose and fasting serum insulin. Echocardiography study was obtained by two dimensionally guided M mode. Results BMI and WHR were significantly higher in obese compared to lean children (P 0.05). Plasma PAI-1 were significantly higher in obese compared to controls (P = 0.03). A significant direct correlation was revealed between PAI-1 in comparison to WHR, fasting insulin and LVM/H. Plasma PAI -1 and WHR were independent predictors of LVM/H. Conclusions Obese children with central fat distribution showed an increase in plasma PAI-1 antigen. Also PAI-1 contributes directly to the complication of obesity including type 2 diabetes and cardiovascular disease.

Electrochemical oxidation of cholesterol in acetonitrile leads to the formation of cholesta-4,6-dien-3-one

Cholesterol was shown to be oxidized at the glassy carbon electrode in an acetonitrile–2-propanol mixture and this oxidation reaction was applied to the determination of serum total cholesterol by high-performance liquid chromatography with electrochemical detection (K. Hojo, H. Hakamata, A. Ito, A. Kotani, C. Furukawa, Y.Y. Hosokawa, F. Kusu, J. Chromatogr. A 1166 (2007) 135–141). To gain insight into the detection mechanisms of cholesterol, an electrolytic product of cholesterol was collected and characterized by infrared spectroscopy, one- and two-dimensional nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The three techniques, together with comparisons of literature spectral data, confirmed the formation of cholesta-4,6-dien-3-one. The conversion of cholesterol to cholesta-4,6-dien-3-one, a four-electron, four-proton electrochemical process, has been proposed as an electrochemical oxidation mechanism of cholesterol in acetonitrile.

Protective effect of apolipoprotein E2 on coronary artery disease in African Americans is mediated through lipoprotein cholesterol

We studied the relationship of apolipoprotein E (apoE) isoforms and coronary artery disease (CAD) in 224 African Americans and 326 Caucasians undergoing diagnostic coronary angiography. The presence of CAD was defined as >50% stenosis in at least one artery. ApoE allele frequencies were 0.12, 0.62, and 0.26 for epsilon 2, epsilon 3, and epsilon 4, respectively, in African Americans and 0.08, 0.78, and 0.14 for epsilon 2, epsilon 3, and epsilon 4, respectively, in Caucasians. Among African Americans, CAD was present in 9 of 34 epsilon 2 carriers (26%), significantly smaller (P < 0.05) in proportion compared with 39 of 82 epsilon 3 carriers and 43 of 92 epsilon 4 carriers (48% and 47%, respectively), suggesting a protective effect of the epsilon 2 allele. No such difference was seen in Caucasians. In African Americans but not Caucasians, LDL cholesterol was lower in epsilon 2 carriers than in epsilon 3 and epsilon 4 carriers (106 vs. 127 and 134 mg/dl, respectively; P < 0.005). After adjusting for lipid levels, the association between apoE2 and CAD was no longer significant. Thus, the protective effect of apoE2 seen in African Americans could be explained by a favorable lipid profile in epsilon 2 carriers, whereas in Caucasians, the absence of such a protective effect could be attributable to the lack of effect of apoE2 on the lipid profile.

Application of Streptomyces and Brevibacterium cholesterol oxidase for total serum cholesterol assay by the enzymatic kinetic method

Background Using non-esterified cholesterol standard, Brevibacterium and Streptomyces are found as suitable sources of cholesterol oxidase for kinetic cholesterol assay. For clinical use, we investigated the suitability of these enzymes for cholesterol determination in human serum. Methods We compared the performance of reagents containing 2 enzymes for the kinetic determination of total serum cholesterol with the standardized endpoint method. Results Reagent containing Streptomyces enzyme was more sensitive than that of Brevibacterium, with linearity up to 20.7 and 2.6 mmol/l, respectively. The analytical reaction for Streptomyces showed a shorter lag phase (148 s) and a steeper slope (absorbance vs. time) than that of Brevibacterium (246 s). The assay using Streptomyces reagent was precise and accurate and compared favorably with the endpoint method ( y = 1.06 x − 0.15, r = 0.996, bias = 0.21 mmol/l). Hemoglobin as high as 7.5 g/l did not interfere while turbidity greater than 2+ (absorbance > 0.778 at 670 nm) and bilirubin concentrations > 171.0 μmol/l did interfere (in a negative interference). Reagent was stable up to at least 8 weeks. Conclusions The Streptomyces cholesterol oxidase, with 3,4-dichlorophenol, proved a suitable source for serum total cholesterol determination by the kinetic method.

Biliary cholesterol crystallization characterized by single-crystal cryogenic electron diffraction

Cholesterol crystals are the building blocks of cholesterol gallstones. The exact structure of early-forming crystals is still controversial. We combined cryogenic-temperature transmission electron microscopy with cryogenic-temperature electron diffraction to sequentially study crystal development and structure in nucleating model and native gallbladder biles. The growth and long-term stability of classic cholesterol monohydrate (ChM) crystals in native and model biles was determined. In solutions of model bile with low phospholipid-to-cholesterol ratio, electron diffraction provided direct proof of a novel transient polymorph that had an elongated habit and unit cell parameters differing from those of classic triclinic ChM. This crystal is exactly the monoclinic ChM phase described by Solomonov and coworkers (Biophysical J., In press) in cholesterol monolayers compressed on the air-water interface. We observed no evidence of anhydrous cholesterol crystallization in any of the biles studied. In conclusion, classic ChM is the predominant and stable form in native and model biles. However, under certain (low phospholipid) conditions, transient intermediate polymorphs may form. These findings, documenting single-crystal analysis in bulk solution, provide an experimental approach to investigating factors influencing biliary cholesterol crystal nucleation and growth as well as other processes of nucleation and crystallization in liquid systems.

Relationships between indices of obesity and its co-morbidities in multi-ethnic Singapore.

To investigate the effect of body mass index (BMI) and body fat distribution as measured by waist-to-hip ratio (WHR) on the cardiovascular risk factor profile of the three major ethnic groups in Singapore (Chinese, Malay and Indian people) and to determine if WHO recommended cut-off values for BMI and WHR are appropriate for the different sub-populations in Singapore. Cross-sectional population study. A total of 4723 adult subjects (64% Chinese individuals, 21% Malay individuals and 15% Indian individuals) were selected through a multi-staged sampling technique to take part in the National Health Survey in 1998. Data on socio-economic status (education level, occupation, housing type) and lifestyle habits (smoking and physical activity), body weight, body height, waist and hip circumferences and blood pressure measured using standardised protocols. Fasting venous blood samples were obtained for determination of serum total cholesterol (TC), high density lipoprotein cholesterol (HDL), low density lipoprotein cholesterol (LDL), triglycerides (TG). Venous blood samples were taken for 2 h oral glucose tolerance test (2 h glu). Absolute and relative risks for at least one cardiovascular risk factor (elevated TC, elevated TC/HDL ratio, elevated TG, hypertension and diabetes mellitus) were determined for various categories of BMI and WHR. At low categories of BMI (BMI between 22 and 24 kg/m(2)) and WHR (WHR between 0.80 and 0.85 for women, and between 0.90 and 0.95 for men), the absolute risks are high, ranging from 41 to 81%. At these same categories the relative risks are significantly higher compared to the reference category, ranging from odds ratio of 1.97 to 4.38. These categories of BMI and WHR are all below the cut-off values of BMI and WHR recommended by WHO. The results show that, at relatively low BMI and WHR, Singaporean adults experience elevated levels of risks (absolute and relative) for cardiovascular risk factors. These findings, in addition to earlier reported high percentage body fat among Singaporeans at low levels of BMI, confirm the need to revise the WHO cut-off values for the various indices of obesity and fat distribution, viz BMI and WHR, in Singapore.

Evaluation of Lp[a] and other independent risk factors for CHD in Asian Indians and their USA counterparts

Conventional risk factors for coronary heart disease (CHD) do not completely account for the observed increase in premature CHD in people from the Indian subcontinent or for Asian Indians who have immigrated to the USA. The objective of this study was to determine the effect of immigration to the USA on plasma levels of lipoprotein [a] (Lp[a]) and other independent risk factors for CHD in Asian Indians. Three subject groups were studied: group 1, 57 subjects living in India and diagnosed with CHD (CHD patients); group 2, 46 subjects living in India and showing no symptoms of CHD (control subjects); group 3, 206 Asian Indians living in the USA. Fasting blood samples were drawn to determine plasma levels of triglyceride (TG), total cholesterol (TC), low density lipoprotein [LDL cholesterol (LDL-Chol)], high density lipoprotein [HDL cholesterol (HDL-Chol)], apolipoprotein B-100 (apoB-100), and Lp[a]. Apolipoprotein [a] (apo[a]) size polymorphism was determined by immunoblotting. Plasma TG, apoB-100, and Lp[a] concentrations were higher in CHD patients than in control and USA groups. CHD patients had higher levels of TC and LDL-Chol and lower HDL-Chol than control subjects. However, the USA population had higher levels of TC, LDL-Chol, and apoB-100 and lower HDL-Chol than control subjects. Plasma Lp[a] levels were inversely correlated with the relative molecular weight of the more abundant of each subject's two apo[a] isoforms (MAI), and CHD patients showed higher frequencies of lower relative molecular weights among MAI. Our observed changes in lipid profiles suggest that immigrating to the USA may place Asian Indians at increased risk for CHD. This study suggests that elevated plasma Lp[a] confers genetic predisposition to CHD in Asian Indians, and nutritional and environmental factors further increase the risk of CHD. This is the first report implicating MAI size as a predictor for development of premature CHD in Asian Indians. Including plasma Lp[a] concentration and apo[a] phenotype in screening procedures may permit early detection and preventive treatment of CHD in this population.

Change of Method for Determination of Serum Total Cholesterol and Verification of It's Accuracy Over the Past Thirty Years

Change of Method for Determination of Serum Total Cholesterol and Verification of It's Accuracy Over the Past Thirty Years

Determination of Total Cholesterol in Hypertriglyceridemic Serums

The determination of serum total cholesterol by a direct reaction involving a Trinder-type enzymic pathway can be severely hampered by the turbidity caused by excessive concentrations of triglyceride-rich lipoproteins such as very-low-density lipoproteins and chylomicrons. This paper describes a clarification procedure that effectively removes such turbidity by a process involving lipolysis of triglycerides and entrapment of the liberated nonesterified fatty acids by alpha cyclodextrin (α-CD) as a transparent host–guest complex. Many elevated triglyceride conditions can be treated by this enzymic clarification procedure as exemplified by spectral investigations. It may still be necessary to determine triglycerides in order to estimate and correct for the dilution of the serum by large lipoproteins containing the triglycerides. The cloudy or milky appearance of a fasting serum suggests that triglyceride determination probably should be performed in any case simply because the appearance of the specimen provides this clue to such an abnormality.

Determination of serum cholesterol by stable isotope dilution method using discharge-assisted thermospray liquid chromatography/mass spectrometry

A discharge-assisted thermospray (plasmaspray) liquid chromatography/mass spectrometric method for the determination of total serum cholesterol is described. The method incorporates stable isotope dilution using (3,4-13C)cholesterol as an internal standard. Liquid chromatographic separation is performed using methanol as a flow solvent and effluents are directly introduced to the mass spectrometer. [MH-H2O]+ ions are monitored during liquid chromatography/mass spectrometry using the selected ion monitoring method. Satisfactory agreement between the analytical result and the certified value of the National Institute of Standards and Technology (formerly National Bureau of Standards) standard reference material serum is obtained with a relative standard deviation of 0.6%.

Microplate methods for determination of serum cholesterol, high density lipoprotein cholesterol, triglyceride and apolipoproteins

Microtiter plate methods were developed for the enzymatic determination of serum total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and triglyceride (TG), and for the turbidometric determination of apolipoproteins. The micromethods resulted in accurate, precise values that were in good agreement with the conventional spectrophotometric assays. The coefficient of variation for TC determinations was 4.5% or less and bias was 5% or less. The lipid micromethod assays are sensitive to 10 mg/dL or less, and the apolipoprotein assay to 1 mg/dL. Less than 100 microL of serum suffices for TC, TG and apoprotein assays; HDL-C requires an additional 100 microL of serum. Advantages of the micromethods include reductions in assay time and in the amount of reagents required.

The Determination of Total Serum Cholesterol by Flowinjection Analysis with Amperometric Detection

Abstract A flow-injection system is described which employs immobilized cholesterol esterase and cholesterol oxidase for the determination of total serum cholesterol. Hydrogen peroxide generated by the enzymatic reaction is measured directly at a platinum electrode held at +600 mV vs Ag/AgCl. Serum samples are passed through an anion exchange resin to remove possible interferences prior to analysis. The accuracy and precision of this system was evaluated with a Standard Reference Material for serum cholesterol and the quantitative performance was found to conform to recent guidelines put forward by the National Institutes of Health's National Cholesterol Education Program.

Total cholesterol in serum determined by isotope dilution/mass spectrometry, with liquid-chromatographic separation.

We describe an accurate, precise method for determination of total serum cholesterol by isotope dilution/mass spectrometry (IDMS) with liquid-chromatographic separation. After adding [3,4-13C]cholesterol to serum and hydrolyzing the cholesterol esters, we extract the total cholesterol. "High-performance" liquid chromatography (HPLC) is used to separate the extracted cholesterol for measurement by electron-impact mass spectrometry with use of a direct-insertion device. To evaluate the specificity and the accuracy of this method, we also studied the conventional IDMS method, which involves converting cholesterol to the trimethylsilyl ether and assay by gas chromatography-mass spectrometry with use of a capillary column. The coefficient of variation for the HPLC method was a little larger than that for the conventional method, but mean values by each method agreed within 1% for all sera tested.