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Generation and use of a tailored gene array to investigate vascular biology.

Vasculogenesis, angiogenesis and vascular remodelling are complex processes where the fate of several cell types is determined by different signalling networks. Many of these networks ultimately function by changing the abundance of RNA transcripts within the cells which constitute blood vessel walls. Researchers can now map these transcript abundance changes using gene array technology. In this review, we describe the design, production and use of a gene array specifically tailored to investigate vascular biology. We describe the advantages of tailored gene arrays, and give detailed protocols based on our experience to allow the reader to use such gene arrays to generate meaningful data. We list the issues to consider when choosing and verifying the genes and splice variants included in an array, and describe our use of Arabidopsis sp. RNA spikes for quality control. We present data that illustrates the absolute necessity for both technical and biological replicates to be incorporated in the design of gene array experiments using primary cells such as HUVECS. Finally, we describe methods for the normalisation and interpretation of the data that gene arrays produce. The approach to gene array technology described here is easily within reach of the budget and expertise of most academic research groups.

Cardiovascular Physiological Phenomena↗

Diazaborine treatment of Baker's yeast results in stabilization of aberrant mRNAs.

Upon Northern blotting, Saccharomyces cerevisiae that was treated with diazaborine showed aberrant mRNAs that were extended at the 3'-end and terminated at secondary processing sites. These bands were also detected in untreated Deltaupf1, Deltaxrn1, and rat7-1 mutants. This finding demonstrates that the aberrant mRNAs also occur in untreated strains in small quantities and can reach the cytoplasm, where they are normally degraded by Xrn1p. Diazaborine treatment stabilizes these mRNAs. The detection of the aberrant bands in the untreated rat7-1 strain indicates that Rat7 is involved in quality control of RNA. The aberrant mRNAs were not detected after diazaborine treatment of a DRG1-1 mutant. Drg1p, a member of the family of AAA (ATPases associated with a variety of cellular activities) proteins, which are thought to represent specific chaperones, may be involved in the process of unfolding the mRNA-ribonucleoprotein complex or in the recognition of aberrant mRNA molecules in the cytoplasm.

Alleles↗

Disruption of mitonuclear coadaptation and compensatory evolution after an extreme dietary shift in carnivorous butterflies.

Mitochondrial function depends on tight coordination between mitochondrial and nuclear genomes, which requires long-term coevolution to maintain mitonuclear coadaptation. While mitonuclear incompatibility is typically studied in the context of hybridization, other evolutionary scenarios that may disrupt coadaptation between the two genomes remain less explored. Here, we propose that extreme ecological niche shifts may disrupt mitonuclear coadaptation, which we test in carnivorous Miletinae butterflies with an extreme dietary transition. By generating high-quality genome assemblies, we found that Miletinae exhibit extensive chromosomal rearrangements. Comparative phylogenomic analyses revealed a striking asymmetric mitonuclear evolutionary response: Miletinae exhibit elevated mitochondrial nucleotide substitution rates compared to phytophagous relatives, whereas nuclear rates remain stable. This shift reverses the typical lepidopteran pattern where nuclear rates exceed mitochondrial rates. Interestingly, this mitochondrial acceleration is driven primarily by relaxed purifying selection rather than positive selection. To sustain mitochondrial function, the nuclear genome of Miletinae underwent pervasive, multilayered compensatory evolution. We detected strong signatures of positive selection and accelerated evolution in nuclear genes directly interacting with mitochondrial components across oxidative phosphorylation (OXPHOS) complexes, the mitochondrial translation, and replication and transcription machinery. Furthermore, this nuclear compensatory response extends to systems governing mitochondrial homeostasis, including protein quality control and RNA degradation and stabilization. Our results support a model in which extreme ecological transitions can disrupt ancestral mitonuclear coadaptation and promote the emergence of a new coadapted state through systemic nuclear compensation. This study broadens the conceptual framework of mitonuclear coevolution and highlights its role in facilitating evolutionary persistence after major ecological shifts.

Animals↗

Multiple site analytical evaluation of a portable blood gas/electrolyte analyzer for point of care testing.

OBJECTIVE: To evaluate the analytical performance of the SenDx 100 portable blood gas and electrolyte analyzer (SenDx Medical, Carlsbad, CA). DESIGN: Accuracy was evaluated by correlation of whole blood patient samples with the Nova Stat Profile 5 (Nova Biomedical, Waltham, MA) and the Ciba Corning 865 (Chiron Diagnostics, Medford, MA). Precision was evaluated using quality control materials (RNA Medical, Acton, MA). SETTING: Critical care laboratories and operating rooms in two institutions. MEASUREMENTS AND MAIN RESULTS: Precision studies performed at three different concentration levels for each analyte demonstrated intra-assay precision of < or =2.5% coefficient of variation and interassay precision of < or =4.0% coefficient of variation in all cases. Analysis of patient specimens in general showed good to excellent correlation to reference analyzers. Regression variables are tabulated. CONCLUSIONS: The SenDx 100 portable blood gas and electrolyte analyzer is a simple and easy to use analyzer demonstrating acceptable performance compared with reference methods.

Blood Gas Analysis↗

Prognostic testing in uveal melanoma by transcriptomic profiling of fine needle biopsy specimens.

Many uveal melanoma patients die of metastasis despite ocular treatment. Transcriptomic profiling of enucleated tumors can identify patients at high metastatic risk. Because most uveal melanomas do not require enucleation, a biopsy would be required for this analysis. Here, we establish the feasibility of transcriptomic analysis of uveal melanomas from fine needle aspirates. Transcriptomic profiles were analyzed from postenucleation "mock" needle biopsies and matching tumors from eight enucleated eyes and from fine needle aspirates in 17 uveal melanomas before radiotherapy. Predictive accuracy was assessed using a weighted voting classifier optimized for probe set selection using a minimal redundancy/maximum relevance algorithm. Transcriptomic profiles from mock biopsies were highly similar to those from their matching tumor samples (P < 0.0001). Transcriptomic profiles from fine needle aspirates clustered into two classes with discriminating probe sets that overlapped significantly with those for our published classification (P < 0.00001). No loss of predictive accuracy was identified among eight needle aspirates obtained from a distant location. Thus, it is feasible to obtain RNA of adequate quality and quantity to perform transcriptomic analysis on uveal melanoma samples obtained by fine needle biopsy. This method can be applied to specimens obtained from distant geographic locations and can stratify uveal melanoma patients based on metastatic risk.

Adult↗

[Improved RT-PCR for detection of PML/RARalpha fusion gene in rapid diagnosis of acute promyelocytic leukemia].

Detection of the PML/RARalpha fusion gene by RT-PCR in acute promyelocytic leukemia (APL) blasts is not only critical to commence promptly the specific therapy with all-trans retinoic acid (ATRA) or arsenic trioxide (As(2)O(3)), but also essential for the definition of PML breakpoint type and subsequent monitoring of minimal residual disease (MRD). The current PML/RARalpha amplification techniques with conventional nested PCR are laborious and time consuming, which fails to meet the requirements for rapid diagnosis of APL in clinical practice. Therefore, an easily handled RT-PCR methodology for the rapid and accurate amplification of PML/RARalpha fusion transcripts is needed. A modified one round RT-PCR protocol was described with a few variations which includes rapid extraction of high quality cellular total RNA, cDNA synthesis with random hexamer and M-MLV reverse transcriptase, optimal concentrations of MgCl(2) (1 mmol/L), PCR primers (0.4 micro mol/L) and Taq polymerase (0.01 U/ micro l), hot-start procedure, and concomitant amplification of PML/RARalpha fusion gene and RARalpha internal control under the identical thermocycle parameters. The results in 40 patients with newly diagnosed APL showed that the improved RT-PCR protocol allowed the rapid detection of PML/RARalpha fusion gene and the accurate discrimination of its transcript types, and simultaneous amplification of RARalpha internal control under the identical program in less than 6 hours. There were no false positive or negative results found with the assay. In conclusion, the assay reported here is proved to be a simple, easily handled, and highly specific procedure for the diagnosis of APL cases, particularly those requiring such urgent therapeutic intervention as ATRA or As(2)O(3) and meriting its further application in APL management.

Humans↗

Monitoring the efficiency of interferon-alpha therapy in chronic myelogenous leukemia (CML) patients by competitive polymerase chain reaction.

Interferon alpha (IFN-alpha) induces cytogenetic responses of variable degree in patients with CML. We sought to establish the relationship between BCR-ABL transcript numbers measured by competitive two-step reverse transcription polymerase chain reaction (RT-PCR) and cytogenetic status in CML patients treated with IFN-alpha. All 398 samples from 163 patients investigated by RT-PCR were positive for BCR-ABL transcripts. In order to standardize results for variability in RNA and cDNA quality, we quantified total ABL transcripts in each sample as internal control. The BCR-ABL/ABL ratios correlated with the cytogenetic results. Quantitative nested PCR allowed the detection of residual BCR-ABL transcripts in all complete cytogenetic responders on IFN-alpha. We conclude that competitive PCR with internal controls is a reliable method for monitoring patients on IFN-alpha and reduces the need for repeated marrow investigations.

Bone Marrow↗

Synovial Chlamydia trachomatis in patients with reactive arthritis/Reiter's syndrome are viable but show aberrant gene expression.

OBJECTIVE: We used reverse transcription-polymerase chain reaction (RT-PCR) assays to assess expression of genes from Chlamydia trachomatis in synovial tissues of patients with reactive arthritis (ReA)/Reiter's syndrome (RS) to determine viability/metabolic activity of the bacterium in joints of infected patients. METHODS: Synovial biopsies were obtained from 18 patients with ReA, RS, or other arthritides; nucleic acids from 16 samples were PCR positive for chlamydial chromosomal DNA. RT-PCR assays targeting primary transcripts from C. trachomatis rRNA operons, and mRNA from the bacterial omp1, hsp60, glyQS, and r-protein S5 and L5 genes, were used to characterize viability/metabolic activity. Host actin mRNA was assessed as control in each sample preparation. RESULTS: RT-PCR of host cell actin mRNA in the 18 patient samples confirmed the quality of all RNA preparations. RNA from 14/16 PCR positive samples was positive by RT-PCR for chlamydial rRNA primary transcripts. Each of these same 14 samples was also RT-PCR positive in assays targeting glyQS, r-protein S5 and L5, and hsp60 mRNA. However, none of the 14 samples showing chlamydial rRNA and mRNA was positive for omp1 transcripts. CONCLUSION: Synovial chlamydia are viable/metabolically active, since primary rRNA transcripts and mRNA from chlamydial genes specifying components of the bacterial protein synthetic system were present in most patient samples assayed. Expression of omp1, encoding the major outer membrane protein, is strongly attenuated in persistently infecting synovial chlamydia, while that of hsp60, specifying a highly immunogenic heat shock protein of the organism, is not downregulated.

Adult↗

[Quality control of plasma(serum) specimen for the detection of HCV RNA with PCR].

OBJECTIVE: To define the optimal collection and storage parameters of serum (plasma) for HCV RNA detection. METHODS: The serum(plasma) obtained from HCV RNA positive patients by different means and different processing and storage conditions, then HCV RNA was detected with the fluorescent quantitative PCR. RESULTS: The centrifugation was performed within 2 hours after formation of the clot, loss of HCV RNA titers was 10.42% and significant loss of HCV RNA titers 40.49% was observed after 4 h. The HCV RNA titers in plasma samples with anticoagulants were much higher than that in serum samples(citrate sodium-anticoagulized 40.97%, EDTA-anticoagulated 53.14%). There was no loss of HCV RNA with up to three freeze-thaw cycles. A significant decrease in HCV RNA(15.6%) was observed at -20 degrees C after one year. CONCLUSIONS: The results suggested that it is important to process and store clinical samples for HCV RNA detection. The EDTA-K2 as anticoagulants the plasma must be collected within 3 h, and the serum must be prepared within 2 hours after hemosposia. It is essential to store the sample under -70 degrees C for the stability of HCV RNA in a longer time.

Blood Specimen Collection↗

Construction of cDNA libraries from small amounts of total RNA using the suppression PCR effect.

Here we describe a method for preparing high-quality cDNA libraries from total RNA. By this method, double-stranded (ds) cDNA ligated with a specially designed ds adaptor is amplified by PCR using a modified T-primer and another primer corresponding to the outer part of the adaptor. The suppression PCR effect strongly inhibits the amplification of poly(A) RNA, thereby reducing background. This method leads to amplification of high-quality cDNA, facilitating the construction of representative cDNA libraries from as little as 10-100 ng of total RNA.

DNA, Complementary↗

CTAB-urea method purifies RNA from melanin for cDNA microarray analysis.

Melanin represents a major problem for the study of melanoma by microarrays since it is retained during RNA extraction and inhibits the enzymatic reactions used for probe preparation. Here we report a new method for cleaning RNA from melanin, based on the use of the cationic detergent cetyl-trimethylammonium bromide (CTAB)-urea for RNA precipitation. This method is easy to perform and has a low cost. Purified RNA is recovered with high quality and good yield. CTAB-urea treated RNA from highly pigmented melanoma cells can be successfully reverse transcribed and labeled to obtain probes which can be subsequently used in cDNA microarray experiments, giving consistent and reproducible results.

Biotechnology↗

Blinded, multicenter quality control study for the quantification of human immunodeficiency virus type 1 RNA in plasma by the Belgian AIDS reference laboratories.

OBJECTIVE: In order to evaluate the interlaboratory variation of HIV-1 RNA measurements in plasma, the Belgian AIDS reference laboratories organized a blinded multicenter quality control study. METHODS: Atest panel of coded spiked HIV-1 plasma samples reflecting the dynamic range of the assay was composed and distributed. The HIV-1 RNA concentration of these samples was determined by the eight Belgian AIDS reference laboratories by means of the Amplicor HIV-1 Monitor version 1.5 assay. RESULTS: Analysis of the results demonstrated that there was little interlaboratory variation for the high concentration range (4.0-5.7 log10 copies/mL), never exceeding 0.2 log10 copies/mL. However the standard deviation for the low concentration range (2.6-3.9 log10 copies/mL) reached up to 0.22 log10 copies/mL. CONCLUSIONS: Since interlaboratory variability never reached 0.5 log10 copies/mL and each of the laboratories was able to detect four-fold differences in plasma HIV-1 RNA levels, the Amplicor assay can be used in multicenter studies without a centralized analysis of samples. Furthermore, this well-characterized proficiency panel of spiked plasma samples could be used as a standard in the study of interassay comparisons.

Belgium↗

Isolation of total RNA from pollens.

Isolation of total RNA from plant materials has been difficult, due to the presence of complex organic substances and the associated pigmentation. In fact, there is a dearth of standardized protocols for isolating total RNA from pollens. To find a simple and reliable method for isolating total RNA from pollen, four methods, viz. phenol/SDS (PS), guanidine HCl (GH), tri-reagent (TR), and modified SDS-betaME (SB) were tested with fresh pollen of Ricinus communis (procured at -70 degrees C) and pollen dried at 30-37 degrees C. The quality and quantity of RNA was superior for the material processed at -70 degrees C. SB gave the highest RNA yield (2.35 mg/g, OD260/280 >2.0), compared to other methods. The results obtained by the SB method were found to be comparable with the widely used tri-reagent method. This was validated with other pollens of Imperata cylindrica and Xanthium strumarium. The yield obtained from graded amounts of pollen was consistent with SB, compared to the TR method. The RNA isolated by SB gave good quality mRNA for synthesizing cDNA. The SDS-betaME method is simple, efficient, and uses less expensive reagents. Hence, we recommend the modified SDS-betaME method for isolating total RNA from pollens.

Guanidine↗

Messenger RNA profiling: a prototype method to supplant conventional methods for body fluid identification.

Conventional methods of body fluid identification use a variety of labor-intensive, technologically diverse techniques that are performed in a series, not parallel, manner and are costly in terms of time and sample. Theoretically, the identification of a body fluid may be made by determining a sufficient number of mRNAs that are expressed exclusively in cells that collectively comprise that body fluid. Advantages of an mRNA-based approach, compared to conventional biochemical methods of analysis, include greater specificity, simultaneous and semi-automatic analysis through a common assay format, improved timeliness, decreased sample consumption and compatibility with DNA extraction methodologies. In this report, we demonstrate that RNA is stable in biological stains and can be recovered in sufficient quantity and quality for analysis. Messenger RNA from the housekeeping genes S15, beta-actin and GAPDH was detected in blood, semen and saliva stains using a sensitive reverse transcriptase-polymerase chain reaction assay (RT-PCR). Additionally, we have identified a number of candidate tissue-specific genes, statherin, histatin 3, PRB1, PRB2 and PRB3 that may be useful for the positive identification of saliva. Messenger RNAs from these genes were detectable in saliva stains but not in blood or semen stains. Collectively these findings constitute the basis of a prototype RNA based assay system that may eventually supplant conventional methods for body fluid identification.

Actins↗

Parameters of human hepatitis delta virus genome replication: the quantity, quality, and intracellular distribution of viral proteins and RNA.

Assembly of hepatitis delta virus (HDV) in infected human hepatocytes involves association of the 1,679- nucleotide single-stranded genomic RNA (deltaRNA) with multiple copies of both small and large forms of the delta protein (deltaAg) to form a ribonucleoprotein particle which in turn interacts with envelope proteins of the natural helper virus, hepatitis B virus. Subsequently, for initiation of a new round of replication, the amount of small deltaAg within the assembled HDV particle is both necessary and sufficient. Quantitative assays were used in order to better understand just how much deltaAg is needed. The molar ratio of deltaAg species to genomic deltaRNA in assembled HDV particles was approximately 200. Next, this ratio was determined for cells under several different experimental situations in which HDV genome replication was occurring. These included replication in woodchuck liver and also in mouse liver and skeletal muscle, as well as replication in stably and transiently transfected cultured human hepatoblastoma cells. Surprisingly, in almost all these situations the molar ratios were comparable to that observed for HDV particles. This was true for different times after the initiation of replication and was independent of whether or not virus assembly was occurring. Cell fractionation combined with quantitative assays was used to test whether the majority of deltaAg and deltaRNA were colocalized during HDV replication in transfected cells. The cytoplasmic fraction contained the majority of deltaAg and genomic deltaRNA. Finally, the quality of deltaAg and deltaRNA, especially at relatively late times after the initiation of replication, was examined by using reverse transcription-PCR, cloning, and sequencing through the entire deltaAg open reading frame. When virus assembly and spread were not possible, 20% or less of the predicted deltaAg would have been able to support HDV replication. In summary, an examination of the quantity, quality and intracellular distribution of deltaAg and deltaRNA in several different experimental systems has provided a better understanding of the parameters associated with the initiation, maintenance, and ultimate decline of HDV genome replication.

Animals↗

Evaluation of a quality assurance program for quantitation of human immunodeficiency virus type 1 RNA in plasma by the AIDS Clinical Trials Group virology laboratories.

A number of quantitative assays have been developed by using amplification techniques to measure human immunodeficiency virus type 1 RNA in the plasma of infected individuals. The Virology Committee of the AIDS Clinical Trials Group in the Division of AIDS, National Institute of Allergy and Infectious Diseases, has established a quality assurance program (QAP) for quantitative assays of HIV-1 RNA levels in plasma. The primary objective of the QAP was to ascertain that a laboratory could maintain the precision required to have a 90% power to detect a fivefold difference in RNA copy number between two samples in the same batch. To achieve this goal, the QAP required an intra-assay standard deviation of no greater than 0.15 log10 RNA copies per ml. Panels for proficiency testing consisted of coded replicate samples and a common set of standards. To date, 41 laboratories have participated in the program and have used both commercial and in-house assays. We demonstrated that 65% of the laboratories were capable of attaining the necessary level of intra-assay precision. The fitted regressions indicated that the differences among laboratories that used the same kit were generally greater than the differences among population-average regressions for the kits themselves. The use of an external QAP and a common set of standards reduced differences both among laboratories that used the same kit and among laboratories that used different kits. Thus, use of a common set of standards across clinical trial protocols would allow for cross-protocol comparisons.

Clinical Protocols↗

Fluorogenic LUX primer for quantitation of HIV-1 by real-time RT-PCR.

Measurement of HIV-1 viral load in plasma is an important marker of disease progression and efficacy of antiretroviral therapy. Real-time polymerase chain reaction (PCR) offers an opportunity to develop more affordable alternative viral load assays. This article reports on the development of a novel real-time reverse-transcriptase (RT)-PCR assay for quantitation of HIV-1 RNA copies. This assay utilizes the LightCycler (version 2) real-time PCR platform and light upon extension (LUX) primer for specific detection of amplicons. An external standard (ES) for quantitation of viral RNA represents an in vitro transcribed RNA. The LUX assay shows a wide linear (R2 = 0.99) dynamic range from 4 x 10(6) to 4 x 10(2) copies/mL. Analytical sensitivity of the assay is 4 x 10(2) copies/mL of ES RNA. Intra- and inter-assay variability of the LUX assay was less than 0.5log(10) copies of ES RNA (i.e., no clinically significant variability was found). Virology quality assurance (VQA) HIV-1 RNA copy controls were used to validate ES and preliminarily evaluate the assay performance. This feasibility study demonstrated that the LUX assay is sensitive, reproducible, and compares well to the Roche Amplicor tests used for characterization of the RNA copy controls. These results suggest further evaluation of the LUX assay using a large cohort of well-characterized samples from HIV-1 positive individuals.

DNA Primers↗