Lipids alter the level and distribution of mouse mammary tumor virus gp52 in vitro.

Linoleic acid, cholesterol, dexamethasone and progesterone were tested by immunocytochemistry and immunoprecipitation for their single and combined effects in vitro on mouse mammary tumor virus (MMTV) gp52 distribution among three compartments: cell-associated antigen, extracellular virus particles and extracellular shed antigen unassociated with virus particles. Results indicated that all additives significantly increased total MMTV gp52 levels and altered the distribution. Linoleic acid and dexamethasone induced the greatest relative proportion of extracellular gp52, whereas cholesterol and progesterone induced the greatest proportion of cell-associated gp52. The implications of these findings for the immune response to mammary tumors is discussed.

Restriction fragment length polymorphism analysis of ERBB2 oncogene by capillary electrophoresis.

Capillary electrophoresis (CE) with a sieving buffer containing ethidium bromide was applied to the detection of PCR-amplified RFLP samples. With CE, in contrast to agarose gel electrophoresis, run times are short, i.e., typically less than 30 min, the capillary can be re-used, and full automation is feasible. The addition of ethidium bromide to the buffer system in conjunction with a field amplification injection technique led to increased sample detectability and resolution. Migration time precision was better than 0.2% RSD with a approximately 12-bp resolution for the DNA fragment sizes of interest. RFLP samples were analyzed for homo- or heterozygosity based on the presence of 500- and/or 520-bp DNA fragments. Special software was used to correct for run-to-run migration time variations, thus facilitating genotype assignment.

False-negative results by polymerase chain reaction due to contamination by glove powder.

The polymerase chain reaction (PCR) technique has become an important, widely employed method for the detection and quantitation of the nucleic acid sequences used in the diagnosis and monitoring of genetic and infectious diseases. Much attention has been directed at the problem of false-positive PCR results, which are generally attributed to low-level laboratory contamination of amplified sequences ("carryover"). In contrast, few investigators have commented on the somewhat less frequent, but equally problematic, false-negative PCR results. Investigation of the source of sporadic false-negative PCR reactions found that glove powder, inadvertently introduced into tubes when gloves are changed in an effort to reduce false-positive results, can nonspecifically inhibit each of the major steps in the PCR detection process. Methodologic precautions are recommended to minimize this problem.

Analysis of DNA restriction fragments and polymerase chain reaction products towards detection of the AIDS (HIV-1) virus in blood.

A high-performance capillary electrophoresis system with a polysiloxane-coated capillary and polymeric buffer additives was investigated for the analysis of DNA restriction fragments and polymerase chain reaction (PCR) products. Mobility data and Ferguson plots of the DNA fragments at different polymer (hydroxypropylmethylcellulose) concentrations indicated that effective molecular sieving was obtained consistent with existing data of conventional gel electrophoresis and with recent HPCE data. The precision and peak efficiency were excellent and the system was applied to the analysis of specific co-amplified DNA sequences (HIV-1 and HLA-DQ-alpha). After PCR, ultrafiltration was used in the sample preparation step to desalt the sample and to remove superfluous PCR reaction products. Electrokinetic injection was used for sample introduction into the capillary. The addition of ethidium bromide to the buffer resulted in longer migration times of DNA fragments and better peak resolution. During HPCE, an artifact associated with dilute DNA solutions leading to the appearance of extra peaks in the electropherogram was found.

Quantitative assessment of HIV-1 DNA load by coamplification of HIV-1 gag and HLA-DQ-alpha genes.

We developed an assay for simultaneous amplification, detection and quantitation of HIV-1 gag gene and the DQ-alpha locus of the histocompatibility (HLA) region of the human genome by polymerase chain reaction (PCR). Crude cell lysates from control cell lines and peripheral blood mononuclear cells (PBMC) from HIV-1-infected and control individuals were coamplified using optimized concentrations of primers directed at both loci, followed by simultaneous hybridization with radioactively labeled HIV-1-gag and HLA-DQ-alpha probes. Simultaneous quantitation of the 242-base-pair HLA and 115-base-pair HIV products was accomplished by both end-point dilution analysis and image analysis of autoradiographs relative to standard curves derived from infected cell lines. We observed good agreement between input cell counts on fresh samples and the HLA-DQ-alpha target copy number values determined by both end-point dilution analysis and comparison of band intensities with standard curves. HIV-1 proviral load in symptomatic patients ranged from 200 to 4000 HIV-PCR-units per 1 x 10(6) PBMC (mean of 1245 copies), whereas asymptomatic patients had levels ranging from two to 1000 HIV-PCR-units per 1 x 10(6) PBMC (mean of 213 copies). This HIV/HLA coamplification approach should be particularly useful for analysis of frozen repository samples from natural history studies, and may facilitate wider application of quantitative PCR analysis.

Rapid simultaneous detection of multiple retroviral DNA sequences using the polymerase chain reaction and capillary DNA chromatography.

The polymerase chain reaction (PCR) technique is a powerful new tool for amplifying target DNA, thus allowing for sensitive detection of specific nucleic acid sequences. One important potential use of PCR involves screening the donated blood supply for transfusion-transmitted viruses. Realization of this goal has been limited by (1) the requirement for multiple, discrete PCR reactions to amplify and detect target sequences of more than one virus, and (2) the lack of a rapid, nonhazardous means for specific detection of one or more PCR-amplified products. We report the simultaneous amplification of three distinct target sequences without discernable loss in sensitivity toward any single target sequence. We also demonstrate very rapid separation and detection of PCR-amplified viral DNA through the use of automated capillary DNA chromatography. Amplified DNA peaks were initially identified by scanning the capillary effluent at ultraviolet wavelengths, while discrimination of human immunodeficiency virus type 1 and human T-cell leukemic virus type I PCR-amplified DNA was accomplished through use of virus-specific, fluorescently labeled primers and probes. These results indicate progress toward an automated system for screening the blood supply for nucleic acid sequences of multiple pathogens.

Application of capillary DNA chromatography to detect AIDS virus (HIV-1) DNA in blood.

The application of capillary DNA chromatography to the detection of the AIDS human immunodeficiency virus, type 1 (HIV-1) proviral DNA in blood is reported for the first time. Combining polymerase chain reaction with fluorescence-labeled DNA probes provides the basis for the amplification and specific detection of the DNA. Samples analyzed for HIV-1 DNA included both infected human blood and cell cultures. The new DNA separation method, capillary DNA chromatography (related to both capillary electrophoresis and capillary hydrodynamic chromatography), is shown to be a powerful method of analysis for DNA. These preliminary results indicate that an automated approach to screening the blood supply for HIV-1 may become a reality in the future.