Treating hyperlipidemia in African Americans.

The purpose of this paper is to provide information concerning the treatment of hyperlipidemia in African Americans. There is a similar prevalence of hypercholesterolemia in Blacks and Whites, but Blacks have been neglected in most pharmacological studies of hyperlipidemia. Intimal atherosclerotic involvement of the aorta and coronary artery occurs in young Black and White males. Epidemiological studies suggest there is a higher mortality rate due to coronary disease in Blacks vs Whites in the United States. Thirty-four percent of Blacks require a fasting lipid profile and 9% of Black adults aged 20 years or older would require lipid-lowering therapy. However, fewer Blacks (26%) than Whites (47%) are aware of their hypercholesterolemia. Studies with lovastatin and pravastatin show efficacy in the treatment of hypercholesterolemia. The Antihypertensive and Lipid Lowering Treatment to Prevent Heart Attack Trial (ALLHAT) is designed to determine all-cause mortality for subjects receiving pravastatin vs a control group receiving "usual care." Randomized, blinded, prospective trials are needed to assess the impact of hyperlipidemia as a risk factor, and the impact of its reduction in African Americans.

Clinical comparison of an enhanced-sensitivity branched-DNA assay and reverse transcription-PCR for quantitation of human immunodeficiency virus type 1 RNA in plasma.

The performance characteristics of an enhanced-sensitivity branched-DNA assay (bDNA) (Quantiplex HIV-1 version 2.0; Chiron Corp., Emeryville, Calif.) and a reverse transcription (RT)-PCR assay (AMPLICOR HIV-1 Monitor; Roche Diagnostic Systems, Inc., Branchburg, N.J.) were compared in a molecular diagnostic laboratory. Samples used in this evaluation included linearity and reproducibility panels made by dilution of a human immunodeficiency virus type 1 (HIV-1) stock culture of known virus particle count in HIV-1-negative plasma, a subtype panel consisting of HIV-1 subtypes A through F at a standardized level, and 64 baseline plasma specimens from HIV-1-infected individuals. Plots of log10 HIV RNA copies per milliliter versus log10 nominal virus particles per milliliter demonstrated that both assays were linear over the stated dynamic ranges (bDNA, r = 0.98; RT-PCR, r = 0.99), but comparison of the slopes of the regression lines (bDNA, m = 0.96; RT-PCR, m = 0.83) suggested that RT-PCR had greater proportional systematic error. The between-run coefficients of variation for bDNA and RT-PCR were 24.3 and 34.3%, respectively, for a sample containing 1,650 nominal virus particles/ml and 44.0 and 42.7%, respectively, for a sample containing 165 nominal virus particles/ml. Subtypes B, C, and D were quantitated with similar efficiencies by bDNA and RT-PCR; however, RT-PCR was less efficient in quantitating subtypes A, E, and F. One non-B subtype was recognized in our clinical specimens based on the ratio of values obtained with the two methods. HIV-1 RNA was quantitated in 53 (83%) baseline plasma specimens by bDNA and in 55 (86%) specimens by RT-PCR. RT-PCR values were consistently greater than bDNA values, with population means of 142,419 and 67,580 copies/ml, respectively (P < 0.01). The results were highly correlated (r = 0.91), but the agreement was poor (mean difference in log10 copies per milliliter +/- 2 standard deviations, 0.45 +/- 0.61) for the 50 clinical specimens that gave discrete values with both methods.

Preclinical evaluation of AMPLICOR hepatitis C virus test for detection of hepatitis C virus RNA.

We compared a single-enzyme, combined reverse transcription-PCR (RT-PCR; AMPLICOR HCV Test; Roche Molecular Systems, Branchburg, N.J.) with an independent, two-enzyme, standard RT-PCR (SRT-PCR) assay for the detection of hepatitis C virus (HCV) RNA in serum and plasma. Test samples included a proficiency testing panel consisting of 10 undiluted plasma samples, three separate dilution series, and sera from 99 patients with chronic liver disease. The quantity of HCV RNA in each patient serum sample was determined by a branched DNA (bDNA) signal amplification assay (Quantiplex HCV-RNA assay; Chiron, Emeryville, Calif.). There was complete concordance between the results of the RT-PCR assays with the 10 undiluted plasma samples used for proficiency testing (3 positive and 7 negative samples). However, the analytical sensitivity of SRT-PCR was 4- to 10-fold greater than that of the AMPLICOR test in the dilution series. HCV RNA was detected in 44, 45, and 40 of the patient serum samples, by SRT-PCR, the AMPLICOR test, and the bDNA assay, respectively. There was 97% agreement between the results of the RT-PCR assays, with only three discrepancies. Review of the patients' medical records resolved all three discrepancies in favor of the AMPLICOR results (two false-negative SRT-PCR results and one false-positive SRT-PCR result). The quantity of HCV RNA in sera from five (11%) patients with viremia detected by AMPLICOR was below the bDNA assay cutoff (< 3.5 x 10(5) RNA equivalents per ml). AMPLICOR compared favorably with SRT-PCR, with key advantages of speed, ease of use, increased sample throughput, and protection against false-positive results because of amplicon carryover.

Early detection of human cytomegalovirus viremia in bone marrow transplant recipients by DNA amplification.

Surveillance blood cultures for human cytomegalovirus (HCMV) are commonly used to identify the bone marrow transplant (BMT) recipients with the highest risk of serious HCMV disease and for whom early interventional ganciclovir therapy would be beneficial. We monitored 36 allogeneic BMT recipients weekly for the presence of HCMV in the blood from 0 to 100 days posttransplantation. Viable HCMV in leukocytes (WBC) was detected by shell vial and tube culture methods. HCMV DNA in WBC and plasma was detected by PCR and DNA hybridization using primers and a probe from the EcoRI fragment D region of HCMV AD169. A uracil-N-glycosylase-dUTP PCR protocol was used to prevent false-positive results due to amplicon carryover. Seventeen patients had multiple consecutive positive samples containing HCMV DNA in plasma or WBC. In 14 of 17 patients, HCMV was also detected by blood culture. HCMV DNA was detected sporadically in six patients, none of whom had positive cultures. One patient had HCMV viremia detected by WBC culture only. The remaining 12 patients had no positive PCR assays or blood cultures. For the patients with positive blood cultures, PCR detection of HCMV DNA in plasma preceded detection of HCMV in culture by a mean of 8 days and detection in WBC preceded detection in culture by 6 days. HCMV disease (interstitial pneumonia) was documented for two patients with viremia (blood culture and PCR positive) and one patient without viremia (blood culture and PCR negative). The earlier recognition of high-risk patients provided by detection of HCMV DNA in plasma or WBC may improve the efficacy of early interventional antiviral therapy.

Isolation of hepatitis C virus RNA from serum for reverse transcription-PCR.

Standard multistep extraction and isolation of RNA for hepatitis C virus (HCV) reverse transcription (RT)-PCR are impractical for routine use in clinical laboratories. We compared three simple commercially available methods for RNA isolation (RNAzol B, TRISOLV, and ULTRASPEC; Biotecx Laboratories, Houston, Tex.) and a total nucleic acid isolation method (IsoQuick; MicroProbe Corp., Garden Grove, Calif.) for the recovery of HCV RNA from sera obtained from 12 viremic patients for RT-PCR. RNAzol B, TRISOLV, ULTRASPEC, and IsoQuick extraction methods detected 87.5, 79.2, 33.3, and 58.3% of the paired positive samples, respectively. The method used for isolation of RNA is an important concern when optimizing HCV RT-PCR.

Direct detection of Mycobacterium tuberculosis in sputum by polymerase chain reaction and DNA hybridization.

A polymerase chain reaction (PCR) assay for the rapid diagnosis of pulmonary tuberculosis was developed by using oligonucleotide primers to amplify a fragment of IS6110, an insertion sequence repeated multiple times in the chromosome of Mycobacterium tuberculosis. Sediment obtained from sputa processed by the N-acetyl-L-cysteine-NaOH method was suspended in a simple lysis buffer and was heated at 100 degrees C for 30 min prior to amplification. A dUTP-uracil N-glycosylase PCR protocol was used to prevent false-positive test results because of the carryover of products from previous amplification reactions. The 317-bp amplicon was detected by direct gel analysis and Southern blotting and then hybridization with a biotin-labeled internal probe. Hybrid molecules were detected by using a commercially available avidin-alkaline phosphatase-chemiluminescent substrate system (Tropix, Inc., Bedford, Mass.). The analytical sensitivity of the assay was 10 fg of purified mycobacterial DNA. The limits of detection by culture (Middlebrook 7H11 agar and Lowenstein-Jensen medium) and by PCR were equivalent in terminal dilution experiments for organism suspensions and positive sputa. An internal control was used to detect the presence of amplification inhibitors in each negative reaction mixture. DNA was purified from inhibitory specimens by phenol-chloroform extraction and ethanol precipitation. PCR results were compared with results of microscopy and conventional culture for the detection of M. tuberculosis in 313 sputum specimens. There were 124 specimens that were positive for M. tuberculosis by conventional methods and 113 (91%) that were positive by PCR. PCR detected 105 of 110 (95%) of the smear-positive and 8 of 14 (57%) of the smear-negative specimens. There were no false-positive results by PCR (specificity, 100%). This PCR assay innovations that make application of this new technology feasible in clinical microbiology laboratories.

Lymphocyte subsets in lymph nodes of homosexual men with generalized unexplained lymphadenopathy. Correlation with morphology and blood changes.

Frozen sections of lymph nodes from 20 homosexual men with chronic generalized lymphadenopathy and of lymph nodes showing follicular hyperplasia from 14 patients without known risk factors of the acquired immunodeficiency syndrome were studied with monoclonal antibodies to T-cell subsets and to the HLA-DR antigen. In T-cell areas of the lymph nodes, excluding tertiary paracortical nodules, the mean T-helper-to-T-suppressor ratio (Th/Ts) +/- 1 SEM was significantly lower in the homosexual group (1.07 +/- 0.06) when compared with the control group (2.49 +/- 0.23), P less than .0001. In seven homosexual men, cell suspensions from the same lymph nodes were analyzed using a fluorescence-activated cell sorter. Results obtained by this method and by immunohistochemistry were comparable except in a homosexual man whose lymph node contained large tertiary paracortical nodules. Although the Th/Ts ratios of the blood and lymph nodes of the same patients were both low, there was not good correlation between the two sets of values (r = .2). Furthermore, there was not good correlation between blood lymphocyte count and lymph node Th/Ts ratios (r = .45). The lymph node Th/Ts ratios of the homosexual patients show less variations compared with the control group. The patient who subsequently developed multiple opportunistic infections had the lowest value. Whether the lymph node Th/Ts ratio has prognostic significance in patients with the lymphadenopathy syndrome warrants further investigation.