Genzyme Diagnostics Research Articles

Prevalence and Risk Factors for Trichomonas Vaginalis Infection Among Women: a Population-Based Controlled Study in Saudi Arabia.

Information on Trichomonas vaginalis (T. vaginalis) infection in Saudi Arabia is scarce. The aim of study was to assess the burden and risk factors of T. vaginalis infection for a cohort of women living in Saudi Arabia. Women aged ≥ 18 years who were seeking medical care at the King Faisal Medical Complex Gynecology Clinic in Taif city, Western Saudi Arabia, were enrolled in a non-randomized case-control study between June 2018 and May 2019. Participants were interviewed using a standard questionnaire for a number of sociodemographic and clinical characteristics. Vaginal swabs obtained from each participant were screened for T. vaginalis infection with direct wet mount smear microscopy, the OSOM Trichomonas rapid test 'OSOM Trich' (Genzyme Diagnostics, Cambridge, MA, USA) and a published nested PCR. Over the study period, 155 women were recruited: 79 with symptoms of vaginitis (i.e. cases) and 76 with no symptoms (i.e. controls). The T. vaginalis infection was detected in ~20% (16/79) of cases and ~9% (7/76) of the controls by the nested PCR. Using the PCR test results as a gold standard, the wet mount microscopy's sensitivity, specificity, negative predictive value, and positive predictive value were 69.5%, 100%, 94.9%, and 100%, respectively, whereas the OSOM Trich's were 86.9%, 100%, 97.7%, and 100%, respectively. The main high-risk factors included age between 30 and 39 years (~35%), marriage for 10 - 30 years (~62%), non-education (~41%), urban residence (~29%), and employment (~36%). Highly significant differences were observed concerning infection distribution among cases for the presence of lower abdominal pain (~64%) and abnormal vaginal discharge (38%) as presenting symptoms (χ2 = 20.42; p < 0.001 and χ2 = 5.63; p = 0.017, respectively). The burden of infection with T. vaginalis is unexpectedly high in the population studied. Regular screening for T. vaginalis infection, particularly in high-risk women, is required.

Factors in the HIV risk environment associated with bacterial vaginosis among HIV-negative female sex workers who inject drugs in the Mexico-United States border region

BackgroundBacterial vaginosis (BV) is the most common cause of vaginitis among women worldwide and is associated with increased susceptibility to sexually transmitted infections (STIs), including HIV. We aimed to determine the impact of the HIV risk environment on BV among female sex workers who inject drugs (FSW-PWIDs) in Tijuana and Ciudad Juarez, Mexico.MethodsWe performed a cross-sectional analysis utilizing baseline data from a randomized controlled trial evaluating a behavioral HIV prevention intervention. Participants underwent testing for BV using the OSOM BVBlue® Rapid Test (Genzyme Diagnostics, San Diego, CA) and completed a survey eliciting information on the HIV risk environment, sexual risk behaviors, and substance use. We applied logistic regression to identify correlates of BV in the physical, social, economic, and political HIV risk environments stratified by study site (Ciudad Juarez vs. Tijuana).ResultsIn total, 584 HIV-negative FSW-PWIDs (300 Ciudad Juarez; 284 Tijuana) were enrolled. The prevalence of BV was 39% (n = 228), which was higher in Ciudad Juarez (56.7%) compared to Tijuana (20.4%). In both cities, micro-level components of the physical HIV risk environment were associated with BV. In Ciudad Juarez, BV was associated with past experiences or threats of physical violence in response to proposed condom use (adjusted odds ratio [aOR] = 3.66, 95% confidence interval [CI]: 1.74–7.69, p = 0.001) and lifetime residence in Ciudad Juarez (aOR = 1.74, 95% CI: 1.05–2.87, p = 0.031). In Tijuana, BV was associated with the number of hours spent on the street daily in the past six months looking for, using, or dealing drugs, engaging in other income generating activities, or sleeping (aOR = 1.05, 95% CI: 1.001–1.097, p = 0.045).ConclusionsOur findings suggest that FSW-PWIDs’ risk of BV may be shaped by the microphysical HIV risk environment. Addressing components of the physical risk environment, including interventions to reduce gender-based violence, may alleviate the burden of BV and subsequent susceptibility to HIV/STIs among FSW-PWIDs in the Mexico/US border region.Trial registrationNational Institute of Health (NIH) Clinical Trials Identifier NCT00840658, and date of NIH trial registration February 7, 2009.

Point-of-Care and Over-the-counter Qualitative Human Chorionic Gonadotropin (hCG) Devices Remain Susceptible to False-Negative Results Caused by Excess hCG β Core Fragment

To the Editor: Previously, we reported false-negative results generated by the OSOM human chorionic gonadotropin (hCG)1 Combo test (Genzyme Diagnostics) (1) and certain lots of the hCG Cardinal Health Combo SP brand rapid test device (SP hCG rapid test; Cardinal Health) (2) owing to increased concentrations of hCG β core fragment (hCGβcf). We refer to this phenomenon as the variant hook effect. In a hospital setting, these false negatives pose a substantial risk of adverse outcomes if pregnant patients are given treatments that can affect the fetus. This observation was reported to the US Food and Drug Administration, but to our knowledge no action has been taken to change these devices. These false negatives also pose considerable risk to women at home, because a negative pregnancy test result may cause delays in prenatal care and continued engagement in behavior that can endanger the fetus. In view of the variable sensitivity of point-of-care (POC) and over-the-counter (OTC) devices to intact and variant forms of hCG as documented in the previously mentioned studies and others (3, 4), we assessed the susceptibility of OTC devices to hCGβcf interference and compared the performance of the most susceptible OTC devices to the 2 …

P55 Evaluation of NAAT and POCT for detecting Trichomonas vaginalis infection in women at a London sexual health clinic

BackgroundTV is a common infection in our clinic, but the true prevalence is likely to be higher since microscopy-the current diagnostic test has a low sensitivity. Nucleic Acid Amplification (NAAT)...

VARIABILITY IN WAXING-INDUCED ETHANOL AND AROMA VOLATILE PRODUCTION AMONG MANDARIN GENOTYPES

VARIABILITY IN WAXING-INDUCED ETHANOL AND AROMA VOLATILE PRODUCTION AMONG MANDARIN GENOTYPES

Altered hepatic lipid metabolism in C57BL/6 mice fed alcohol: a targeted lipidomic and gene expression study

Chronic alcohol consumption is associated with fatty liver disease in mammals. The object of this study was to gain an understanding of dysregulated lipid metabolism in alcohol-fed C57BL/6 mice using a targeted lipidomic approach. Liquid chromatography tandem mass spectrometry was used to analyze several lipid classes, including free fatty acids, fatty acyl-CoAs, fatty acid ethyl esters, sphingolipids, ceramides, and endocannabinoids, in plasma and liver samples from control and alcohol-fed mice. The interpretation of lipidomic data was augmented by gene expression analyses for important metabolic enzymes in the lipid pathways studied. Alcohol feeding was associated with i) increased hepatic free fatty acid levels and decreased fatty acyl-CoA levels associated with decreased mitochondrial fatty acid oxidation and decreased fatty acyl-CoA synthesis, respectively; ii) increased hepatic ceramide levels associated with higher levels of the precursor molecules sphingosine and sphinganine; and iii) increased hepatic levels of the endocannabinoid anandamide associated with decreased expression of its catabolic enzyme fatty acid amide hydrolase. The unique combination of lipidomic and gene expression analyses allows for a better mechanistic understanding of dysregulated lipid metabolism in the development of alcoholic fatty liver disease.

SiRNA-induced liver ApoB knockdown lowers serum LDL-cholesterol in a mouse model with human-like serum lipids

Increased serum apolipoprotein (apo)B and associated LDL levels are well-correlated with an increased risk of coronary disease. ApoE⁻/⁻ and low density lipoprotein receptor (LDLr)⁻/⁻ mice have been extensively used for studies of coronary atherosclerosis. These animals show atherosclerotic lesions similar to those in humans, but their serum lipids are low in apoB-containing LDL particles. We describe the development of a new mouse model with a human-like lipid profile. Ldlr CETP⁺/⁻ hemizygous mice carry a single copy of the human CETP transgene and a single copy of a LDL receptor mutation. To evaluate the apoB pathways in this mouse model, we used novel short-interfering RNAs (siRNA) formulated in lipid nanoparticles (LNP). ApoB siRNAs induced up to 95% reduction of liver ApoB mRNA and serum apoB protein, and a significant lowering of serum LDL in Ldlr CETP⁺/⁻ mice. ApoB targeting is specific and dose-dependent, and it shows lipid-lowering effects for over three weeks. Although specific triglycerides (TG) were affected by ApoB mRNA knockdown (KD) and the total plasma lipid levels were decreased by 70%, the overall lipid distribution did not change. Results presented here demonstrate a new mouse model for investigating additional targets within the ApoB pathways using the siRNA modality.

Glucose stimulates cholesterol 7α-hydroxylase gene transcription in human hepatocytes

Bile acids play important roles in the regulation of lipid, glucose, and energy homeostasis. Recent studies suggest that glucose regulates gene transcription in the liver. The aim of this study was to investigate the potential role of glucose in regulation of bile acid synthesis in human hepatocytes. High glucose stimulated bile acid synthesis and induced mRNA expression of cholesterol 7alpha-hydroxylase (CYP7A1), the key regulatory gene in bile acid synthesis. Activation of an AMP-activated protein kinase (AMPK) decreased CYP7A1 mRNA, hepatocyte nuclear factor 4alpha (HNF4alpha) protein, and binding to CYP7A1 chromatin. Glucose increased ATP levels to inhibit AMPK and induce HNF4alpha to stimulate CYP7A1 gene transcription. Furthermore, glucose increased histone acetylation and decreased H3K9 di- and tri-methylation in the CYP7A1 chromatin. Knockdown of ATP-citrate lyase, which converts citrate to acetyl-CoA, decreased histone acetylation and attenuated glucose induction of CYP7A1 mRNA expression. These results suggest that glucose signaling also induces CYP7A1 gene transcription by epigenetic regulation of the histone acetylation status. This study uncovers a novel link between hepatic glucose metabolism and bile acid synthesis. Glucose induction of bile acid synthesis may have an important implication in metabolic control of glucose, lipid, and energy homeostasis under normal and diabetic conditions.

False-Negative Results from Point-of-Care Qualitative Human Chorionic Gonadotropin (hCG) Devices Caused by Excess hCGβ Core Fragment Vary with Device Lot Number

Recently, we reported that increased concentrations of human chorionic gonadotropin β core fragment (hCGβcf)1 can cause false-negative results on the OSOM® hCG Combo Test (Genzyme Diagnostics) and ICON® 25 hCG (Beckman Coulter) qualitative urine hCG devices (1). We reported that the hCG Combo SP® Brand Rapid Test device (SP® hCG Rapid Test; Cardinal Health), however, was not subject to the same effect. We demonstrate that the false-negative effect is observable with certain lots of the Combo SP devices. Approximately 9 months after our hospital system switched to the Combo SP Rapid Test device to avoid potential false-negative results in patients with high concentrations of urine hCGβcf, we encountered 2 patients with false-negative results. Patient 1 was 18 years of age with a live intrauterine pregnancy that was seen on ultrasound and estimated at 12 weeks gestation. She presented to the emergency department (ED) with abdominal pain (no bleeding). Her diagnosis at discharge was hyperemesis gravidarum and dehydration. Her urine was cloudy with a pH of 6.5, a specific gravity of 1.026, and a 1+ leukocyte esterase result. A point-of-care urine pregnancy test was performed in the ED (Combo SP Rapid Test …

Repetition of the rapid antigen test in initially negative supposed streptococcal pharyngitis is not necessary in adults

To determine whether the repetition of the rapid antigen detection test (RADT) in patients, with a high suspicion of presenting pharyngitis by group A beta-haemolytic streptococci (GABHS), with a previously negative test improves the validity of the test. Two hundred and twenty-two patients aged 14 years or more with acute pharyngitis and two or more Centor criteria--tonsillar exudates, fever, tenderness in the lymph glands and/or absence of cough--were consecutively recruited. In all patients, a pharyngotonsillar sample was obtained with two swabs, one for the RADT (OSOM Strep A Genzyme test, Genzyme Diagnostics, Cambridge, MA, USA) and the other was sent to the Department of Microbiology for culture. In patients with a negative RADT, the determination was repeated. The sensitivity, specificity and predictive values were determined. Cultures were positive for GABHS in 55 patients (24.8%). Three false-negatives and 14 false-positives were observed by comparing the rapid test with throat culture, achieving a sensitivity of 94.5% and a specificity of 91.6%. Positive and negative predictive values were 78.8% and 98.1% respectively. Taking the second determination in the negative cases into account, the results were 96.4%, 91.6%, 79.1% and 98.7% respectively. The negative predictive value achieved with the RADT determination was very high. Repetition of the test only slightly improved this percentage, making repetition of this test unnecessary.

False-Negative Results in Point-of-Care Qualitative Human Chorionic Gonadotropin (hCG) Devices Due to Excess hCGβ Core Fragment

During pregnancy, human chorionic gonadotropin (hCG) immunoreactivity in urine consists of intact hCG as well as a number of hCG variants including the core fragment of hCGbeta (hCGbeta cf). We identified 3 urine specimens with apparent false-negative results using the OSOM(R) hCG Combo Test (Genzyme Diagnostics) qualitative hCG device and sought to determine whether an excess of 1 of the fragments or variants might be the cause of the interference. We measured concentrations of hCG variants in the urine from 3 patients with apparent false-negative hCG results. Purified hCG variants were added to urines positive for hCG and tested using the OSOM, ICON(R) 25 hCG (Beckman Coulter), and hCG Combo SP(R) Brand (Cardinal Health) devices. Dilution of these 3 urine samples resulted in positive results on the OSOM device. Quantification of hCG variants in each of the 3 patient urine specimens demonstrated that hCGbeta cf occurred in molar excess of intact hCG. Addition of purified hCGbeta cf to hCG-positive urines caused false-negative hCG results using the OSOM and ICON qualitative urine hCG devices. Increased concentrations of hCGbeta cf can cause false-negative results on the OSOM and ICON qualitative urine hCG devices.

Rapid Antigen Testing Compares Favorably with Transcription-Mediated Amplification Assay for the Detection of Trichomonas vaginalis in Young Women

Diagnosis of Trichomonas vaginalis (TV) infection is limited by imperfect testing methods. Newer tests, such as rapid antigen and nucleic acid amplification tests, are often compared with culture, which is not widely used but is more sensitive than wet mount. We assessed the sensitivity and specificity of 4 tests for the identification of TV using 3 statistical approaches. Sexually active adolescent women aged 14-21 years (n=330) were recruited from a teen health center and emergency department. Vaginal swabs were tested for TV using wet mount, culture (InPouch TV; Biomed Diagnostics), rapid antigen testing (OSOM TV; Genzyme Diagnostics), and transcription-mediated amplification testing (TMA; APTIMA TV analyte specific reagents; Gen-Probe). TV was detected in 61 participants (18.5%). Compared with a composite reference standard (i.e., any TV test with positive results), the sensitivities of wet mount, culture, rapid antigen testing, and TMA were 50.8%, 75.4%, 82%, and 98.4%, respectively. Using latent class analysis, the sensitivity of wet mount (56%) was significantly lower than that of other tests, and the sensitivities of culture and rapid antigen testing were similar (83% and 90%, respectively); specificity was 100% for each of these 3 methods. TMA had a sensitivity of 98.2% and a specificity of 98%. Tests performed equally well regardless of whether the participant had bleeding or other infections. The sensitivities of the rapid antigen test and TMA were comparable (92.5% and 97.5%, respectively) in women who had vaginal symptoms. Wet mount alone is insufficient for the reliable diagnosis of TV infection in women. TMA and rapid antigen tests are highly sensitive and specific, and both are superior to wet mount. Rapid antigen testing is equivalent to culture, and it compares favorably with the sensitivity of TMA for the detection of TV.

Use of an Immunochromatographic Assay for Rapid Detection of Trichomonas vaginalis in Vaginal Specimens

Trichomonas vaginalis infection is estimated to be the most widely prevalent nonviral sexually transmitted infection in the world. Wet-mount microscopy is the most common diagnostic method, although it is less sensitive than culture. The OSOM Trichomonas Rapid Test (Genzyme Diagnostics, Cambridge, Mass.) (referred to here as OSOM) is a new point-of-care diagnostic assay for T. vaginalis that uses an immunochromatographic capillary flow (dipstick) assay and provides results in 10 min. The purpose of this study was to determine the test characteristics of OSOM compared to those of a composite reference standard (CRS) comprised of wet-mount microscopy and T. vaginalis culture. This multicenter cross-sectional study enrolled sexually active women > or =18 years of age who presented with symptoms of vaginitis, exposure to T. vaginalis, or multiple sexual partners. Vaginal-swab specimens were obtained for T. vaginalis culture, wet mount, and rapid testing. The prevalence of T. vaginalis in this sample was 23.4% (105 of 449) by the CRS. The sensitivity and specificity of OSOM vaginal-swab specimens were 83.3 and 98.8%, respectively, while wet mount had a sensitivity and specificity of 71.4 and 100%, respectively, compared to the CRS. OSOM performed significantly better than wet mount (P = 0.004) and detected T. vaginalis in samples that required 48 to 72 h of incubation prior to becoming culture positive. The performance of the rapid test was not affected by the presence of coinfections with chlamydia and gonorrhea. The OSOM Trichomonas Rapid Test is a simple, objective test that can be expected to improve the diagnosis of T. vaginalis, especially where microscopy and culture are unavailable.

Some commercial preparations of Escherichia coli bacterial endotoxin lipopolysaccaride (LPS) are contaminated with biologically active substances.

The Escherichia coli (E. coli) endotoxin lipopolysaccharide (LPS) is a potent activator of the immune system and is commonly used to induce inflammation both in the periphery and in the central nervous system. Previously, we showed that exposure of slices of rat parietal cortex to LPS (50 µg/mL) apparently promoted the rapid releases of glutamate, [3H]norepinephrine ([3H]NA), and adenosine (Wang and White 1999). Release of [3H]NA appeared to be secondary to the released glutamate acting at both NMDA and non-NMDA receptors. We attempted to characterize further the effects of LPS on neurotransmitter and neuromodulator release in the brain. Unexpectedly, we found that various preparations of LPS were contaminated with both glutamate and adenosine at concentrations approximating those detected during exposure of brain slices to LPS. We must now conclude that LPS does not promote the rapid releases of glutamate, [3H]NA or adenosine in the brain. The evidence leading us to this conclusion is presented below. The LPS (E. coli 0127:B8 lot #118H4033, #20K4047, #11H4085, and E. coli 026:B6, lot #118H4102) and glutamate were purchased from Sigma (St Louis, MO, USA). l-[3H]Norepinephrine ([3H]NA), Solvable and Ecolite were purchased from DuPont-New England Canada Inc. (Markham, Ontario, Canada). Glutamate dehydrogenase (GDH; EC 1.4.1.2; 40 U/mL) was obtained from Genzyme Diagnostics (Cambridge, MA, USA). Chloroacetylaldehyde was acquired from Aldrich Chemical Company (Milwaukee, WI, USA). All procedures involving animals were approved by the Dalhousie University Animal Care Committee according to the guidelines of the Canadian Council on Animal Care. Slices of rat parietal cortex were prepared and superfused as previously described (Hoehn and White 1990a, 1990b; Wang and White 1999). Glutamate was measured using a fluorometric assay (Nicholls and Sihra 1986; Wang and White 1999). [3H]NA in the superfusate was detected using liquid scintillation spectrometry (Wang and White 1999). Lastly, adenosine was measured according to the method of Wojcik and Neff (1982) with some modifications (Wang and White 1999). The effects of dialyzed LPS (Sigma 0127:B8 lot #118H4033) were compared with those of undialyzed LPS (50 µg/mL) (Fig. 1). Although undialyzed LPS (0127:B8 lot #118H4033) apparently released glutamate, [3H]NA and adenosine as found previously (Wang and White 1999), dialyzed LPS did not (Fig. 1). Similarly, purified LPS (Sigma 0127:B8, lot #11H4085) did not release glutamate, adenosine or [3H]NA from slices of rat parietal cortex (data not shown). Effect of undialyzed LPS (●, 0127:B8 lot #118H4033; 50 µg/mL) and dialyzed LPS (○, 0127:B8 lot #118H4033; 50 µg/mL) on glutamate (GLU), [3H]NA, and adenosine (ADO) contents of dialysate from rat parietal cortex. (a) GLU, (b) [3H]NA and (c) ADO. Dialyzed LPS had no effect on GLU, [3H]NA, or adenosine levels in dialysate from slices of rat parietal cortex. Values are means ± SEM from four experiments. Subsequently, another lot (Sigma 0127:B8 lot #20K4047), another serotype (Sigma 026:B6 lot #118H4102) and purified LPS (Sigma 0127:B8, lot #11H4085) were examined for contamination with glutamate and adenosine (Table 1). All three of the unpurified lots of LPS were contaminated with glutamate and adenosine, although to varying extents. Purified and dialyzed LPS were not contaminated with either glutamate or adenosine (Table 1). These results indicate that several preparations of LPS are contaminated to varying extents with appreciable amounts of glutamate and adenosine. This is surprising because initial studies failed to detect glutamate contamination of LPS (Wang and White, unpublished observations). Furthermore, both dialyzed and purified preparations of LPS failed to release glutamate, [3H]NA or adenosine from slices of rat parietal cortex. Thus our previous findings showing that LPS apparently evoked the releases of glutamate, [3H]NA and adenosine (Wang and White 1999) were, in fact, likely to result from the contamination of the LPS by glutamate and adenosine. We are now forced to conclude that LPS does not cause rapid excitation. We apologize for any difficulties that our previous conclusions concerning possible rapid actions of LPS in the brain may have caused. It seems highly likely that non-purified preparations of LPS are also contaminated with other biologically active molecules. Hence, great care must be taken when interpreting results obtained with low-purity LPS preparations, as the influence of contaminating biologically active molecules should not be ignored. The authors thank Zaiping Liu for her excellent technical assistance. This research was supported by grants to TDW from the Medical Research Council (CIHR) of Canada and the Dalhousie University Medical Research Foundation.

Reference standardization and analytical performance of a liquid homogeneous high-density lipoprotein cholesterol method compared with chemical precipitation method.

The use of high-density lipoprotein cholesterol (HDL-C) levels as a risk factor for coronary heart disease necessitates an accurate and precise method for measuring HDL-C. The Centers for Disease Control and Prevention HDL-C reference method (RM) and designated comparison method (DCM) are time-consuming, expensive, and impractical for routine clinical use. We evaluated the Liquid N-geneous (LN-gen) HDL-C assay (Genzyme Diagnostics, Cambridge, Mass) to determine if this homogeneous reagent meets the National Cholesterol Education Program requirements for HDL-C evaluation. Accuracy of the LN-gen HDL-C assay was compared in combination with phosphotungstic acid (PTA) precipitation with DCM HDL-C for normotriglyceridemic serum specimens (triglycerides < 2.0 g/L) and with RM HDL-C for specimens with triglycerides levels > or = 2.0 g/L. Genzyme Diagnostics (with RM and DCM assayed by Pacific BioMetrics Inc, Seattle, Wash) and the Lipid Reference Laboratory of the University Hospital Rotterdam, The Netherlands. Linear regression to DCM (n = 90) was (LN-gen = 1.015 DCM + 0.01 g/L, r = 0.993, SE = 0.015 g/L) and (PTA = 1.004 DCM - 0.017 g/L, r = 0.980, SE = 0.025 g/L), with a mean percent bias to DCM of 3.3% and -2.8% for LN-gen and PTA, respectively. The comparison with RM (n = 69) showed an increased mean bias for PTA (-5.8%) as compared with LN-gen (1.5%). The correlation and regression equations were (LN-gen = 1.020 RM - 0.002 g/L, r = 0.985, SE = 0.017 g/L) and (PTA = 1.042 RM - 0.032 g/L, r = 0.984, SE = 0.018 g/L). The precision of LN-gen was confirmed at < 2.1% coefficient of variation, and the total error was calculated to be < or = 7.7% for both normotriglyceride and elevated triglyceride specimens at HDL-C decision points of 0.35 g/L and 0.60 g/L. The LN-gen HDL-C assay offers a cost-effective convenient method for meeting the 1998 precision, bias, and total error recommendations of the National Cholesterol Education Program.

Evaluation of a rapid homogeneous method for direct measurement of high-density lipoprotein cholesterol.

We evaluated the performance of a direct Liquid N-geneous HDL-C assay (N-HDL; Genzyme Diagnostics, Cambridge, Mass) and compared it with a Centers for Disease Control and Prevention (CDC) modified reference procedure (M-REF) and phosphotungstic acid (PTA) precipitation method in patients with normotriglyceridemia (triglyceride level, <400 mg/dL) and hypertriglyceridemia (triglyceride level, > or =400 mg/dL). Excellent intra-assay and interassay coefficients of variation were obtained (<2.0%) using the N-HDL assay. The N-HDL and PTA assays correlated well with M-REF in normotriglyceridemic samples. In hypertriglyceridemic samples, however, the N-HDL method exhibited better correlation with M-REF than the PTA assay. In addition, compared with M-REF, the mean absolute percentage bias of N-HDL was lower than the PTA assay in normotriglyceridemic (4.9% vs 5.8%) and hypertriglyceridemic (5.4% vs 12.9%) samples. Hemolysis, ascorbic acid, and bilirubin did not interfere with the N-HDL assay. On the basis of these findings, the N-HDL assay compares favorably with the modified CDC reference method and seems superior to the PTA assay. It also has the advantage of being suited for complete automation and, thus, would prove useful in large clinical laboratories.

Evaluation of Homogeneous High-Density Lipoprotein Cholesterol Assay on a BM/Hitachi 747–200 Analyzer

Because of the inverse correlation that exists between serum HDL-C concentration and risk of atherosclerotic disease (1), monitoring of high-density lipoprotein cholesterol (HDL-C) in serum is clinically important. In 1993, the National Cholesterol Education Program Adult Treatment Panel II (NCEP ATP II) revised its guidelines for diagnosis and treatment of hypercholesterolemia in adults to include HDL-C measurement at the initial screening stage when total cholesterol is measured (2). The enhanced role of HDL-C in clinical practice increases the need for reliable and readily performable HDL-C measurement. Most routine laboratories use a two-step method: chemical precipitation of lipoproteins containing apoprotein B, then quantification of HDL as cholesterol remaining in the supernate. Such precipitation-based methods are time-consuming, labor-intensive, require relatively large volumes of serum, and cannot be fully automated. Recently, several methods of direct HDL-C measurement have become commercially available, including the use of magnetically responsive particles with polyanion-metal combinations (3), the use of polyethylene glycol (PEG) with antibodies against apoprotein B and apoprotein CIII (4)(5), and the use of PEG-modified enzymes and sulfated α-cyclodextrin (6)(7). Okazaki et al. (8) also recently proposed the use of high-performance liquid chromatography (HPLC) as a tool to compare different methods for HDL-C. The goal of this study was to evaluate three assays for homogeneous HDL-C on BM/Hitachi 747–200 Automatic Analyzer (Boehringer Mannheim Corp.): the direct HDL-cholesterol reagent kit (Boehringer Mannheim Corp.), the N-geneousTM HDL cholesterol reagent kit (Genzyme Diagnostics), and EZ-HDLTM cholesterol reagent kit (Sigma Diagnostics). For each HDL-C assay, the reagent kit contains Reagent 1 and Reagent 2; Reagent 1 is liquid, and Reagent 2 is lyophilized. Reaction principles of these three methods are quite different; the direct-HDL uses PEG-modified cholesterol esterase and cholesterol oxidase as well as sulfated α-cyclodextrin to provide selective determination of HDL-C in serum; …