Atrial Fibrillation and the Prognostic Performance of Biomarkers in Heart Failure

BACKGROUND: Consideration of circulating biomarkers for risk stratification in heart failure (HF) is recommended, but the influence of atrial fibrillation (AF) on prognostic performance of many markers is unclear. We investigated the influence of AF on the prognostic performance of circulating biomarkers in HF. METHODS: N-terminal pro-B-type natriuretic peptide (NT-proBNP), mid-regional-pro-atrial natriuretic peptide, C-type natriuretic peptide (CNP), NT-proCNP, high-sensitivity troponin-T, high-sensitivity troponin-I, mid-regional-propeptide adrenomedullin, co-peptin, growth differentiation factor-15, soluble Suppressor of Tumorigenicitiy (sST2), galectin-3, and procalcitonin plasma concentrations were measured in a prospective, multicenter study of adults with HF. AF was defined as a previous history of AF, and/or presence of AF/flutter on baseline 12-lead electrocardiogram. The primary outcome was the composite of HF-hospitalization or all-cause mortality at 2 years. RESULTS: Among 1099 patients (age 62 +/- 12years, 28% female), 261(24%) patients had AF. Above-median concentrations of all biomarkers were independently associated with increased risk of the primary outcome. Significant interactions with AF were detected for galectin-3 and sST2. In considering NT-proBNP for additive risk stratification, sST2 (adjusted hazard ratio [AHR]1.85, 95%confidence interval [C.I.] 1.17-2.91) and galectin-3 (AHR1.85, 95%C.I. 1.09-2.45) were independently associated with increased primary outcome only in the presence of AF. The prognostic performance of sST2 was also stronger in AF for all-cause mortality (AF: AHR2.82, 95%C.I. 1.26-6.21; non-AF: AHR1.78, 95% C.I. 1.14-2.76 without AF), while galectin-3 predicted HF-hospitalization only in AF (AHR1.64, 95%C.I. 1.03-2.62). CONCLUSIONS: AF modified the prognostic utility of selected guideline-endorsed HF-biomarkers. Application of markers for prognostic purposes in HF requires consideration of the presence or absence of AF

Expression of atrial natriuretic factor in transgenic potatoes

This thesis describes the expression of the precursor molecule of rat atrial natriuretic factor, ANF-(1-126), in transgenic potatoes (Solanum tuberosum L. cultivar Iwa). Four ANF gene fusions were constructed for extracellular expression of ANF-(1-126) either by retaining the native signal peptide of ANF or replacing it with the secretory signal of a pathogenesis-related protein from tobacco. Two of the constructs were targeted for constitutive expression by transcriptional fusion with the CaMV 35S promoter. The other two were driven by a 0.7-kb tuber-specific patatin promoter that was isolated by PCR amplification from potato cultivar Maris Piper. Enhancement of expression was attempted by fusing the 5' untranslated leader from the tobacco mosaic virus immediately downstream of the promoter but preceding the coding sequence. All chimaeric fusions were terminated by the 3' termination sequence from the transcript of gene 7 of the octopine-type Ti-plasmid, pTiA6. Two similar constructs were also made for constitutive or tuber-specific expression of cytosolic beta-glucuronidase (GUS) to confirm the functionality of the DNA regulatory sequences used. All six chimaeric gene fusions were cloned into the binary vector, pGA643, or its derivative. These were then introduced into potato plants via leaf disc transformation using Agrobacterium tumefaciens strain LBA4404 carrying the disarmed helper Ti-plasmid, pAL4404. About 300-400 kanamycin-resistant plants were obtained per 100 leaf explants inoculated. Morphological abnormalities were observed among some regenerants but most of these were transient. Seventy-seven kanamycin-resistant regenerants were analysed by Southern blotting of which 75% were found to contain detectable T-DNA sequences. Seventy-six percent of these were one or two copy transformants. Incomplete T-DNA transfer and rearrangements were observed among some transformants. The possible presence of endogenous ANF-homologues in potato genomic DNA was revealed by two weak hybridising bands consistently observed with both non-transformed and transformed potato plants. Northern analysis confirmed that ANF and GUS mRNA were transcribed correctly and efficiently in potato with ANF transcripts comigrating with that from murine cardiac tissues. The activity of the 35S and patatin promoters was found to be appropriate with respect to tissue/organ specificity. Under the 35S promoter, ANF and GUS mRNA accumulated to much higher levels in leaves compared with tubers. Patatin driven expression was tuber specific but promoter activity was weaker than that of 35S. Both ANF and GUS mRNA levels generally coincided with the copy number status of the transformant. The possible presence of a partial homologue of mammalian ANF in potatoes was alluded to by the presence of weak hybridising sequences in potato RNA to rat ANF cDNA. Histochemical analysis of GUS transformants showed strong GUS expression coinciding with the activity and tissue-specificity of the promoters used. Immunoblot experiments revealed a 16-kDa protein which may correspond to the product of transcripts from endogenous ANF-homologues deduced from Southern and Northern blot data. Western analysis of crude acid-extractable protein fractions from high ANF mRNA expressors failed to show the presence of any ANF-(1-126) in leaves or tubers. In vitro translation experiments indicated the possibility of poor translatability of ANF mRNA for failure in protein expression. This was further substantiated by analysis of codon usage which revealed incompatibilities between the co dons found in ANF and those preferred in potatoes. Reconstitution experiments with proANF from murine cardiac tissues added to ground untransformed tubers showed ANF degradation, indicating the instability of proANF in vitro and, possibly, in vivo. It was proposed that translational or post-translational control be investigated to obtain ANF expression at the protein level. Redesign of the coding sequence of ANF to incorporate potato preferred codons without changing the primary amino acid sequence was suggested. Another option was to target proANF to an organellar compartment where it may be more stable. Targeting proANF to the chloroplast may pose certain problems with post-translational modification. Sequestration of proANF in the vacuoles or its retention in the endoplasmic reticulum was advocated

Cloning of an animal promoter in a plant expression vector

A chimaeric triple component construct was cloned into the binary vector pEND4K to allow the detection of animal promoter activity in plants. The construct comprised the bacterial reporter gene, GUS (beta-glucuronidase), flanked by the 5'- promoter of the rabbit uteroglobin (UG) gene and the 3' termination sequence of the octopine synthase gene. This hybrid was constructed by Bam HI digestion of the plasmid pUG400, to recover the 400-bp UG promoter. Subsequently, this 400-bp promoter fragment was cloned into the Bam HI site in place of the 35S promoter region of the plant expression vector, pKiwi101. The resulting recombinant, pUG400/GUS, was treated with Xba I and Xho I restriction endonucleases to isolate the whole construct which was finally cloned into the binary vector, pEND4K

Concentrating nanoparticles in environmental monitoring

There are significant challenges in assessing the toxicity of nanoparticles in the environment in which effective methods for detection are crucial. An inexpensive method that uses superhydrophobic well with an evaporating droplet followed by a simple squeeze flow is described here and found to provide practical high nanoparticle collection from samples for detection. The process could be hastened by placing a radiant heater close to the droplet if temperature rises in the sample can be tolerated

MicroRNA expression profiles of human left ventricle derived cardiac cells in normoxic and hypoxic conditions

Studies in the cardiovascular research field have demonstrated the vital roles of microRNAs for proper cardiovascular development and functional maintenance. The involvement of aberrant microRNA expression leading to ontogenesis of cardiovascular diseases lends further support of the regulatory role of microRNAs in heart function. Hypoxic insult is one of the major factors that trigger downstream signal cascades which contribute to the pathogenesis of hypoxic/ischemic-related heart diseases. Here, we report the microRNA expression profile in human cardiac-derived cells subjected to 120-h hypoxic treatment. By comparing with the normoxic control state, we identified microRNAs differentially expressed in cardiac cells subjected to hypoxic challenge. MicroRNA microarray data are available at NCBI under the GEO accession number, GSE55387

A direct heating model to overcome the edge effect in microplates

10.1016/j.jpba.2014.09.021Journal of Pharmaceutical and Biomedical Analysis102199-20

Growth measurement of surface colonies of bacteria using augmented reality

The provision of hands-on wet lab training for students to perform micro-organism proliferation experiments is useful for experiential skills development. However, the risk of laboratory-acquired infections arising from inadvertent ingestion, inhalation or skin penetration of these micro-organisms presents a safety concern. To obviate this risk, an augmented reality exercise requiring only a tablet/smartphone, and a petri dish with appropriate markers, was devised to allow students to study Escherichia coli colony growth on agar plates. Positive responses were obtained from a pilot study conducted with high school and undergraduate students on its use