Amorphous/nanocrystalline silicon pi'ii'n devices fabricated on micromachined glass substrates are integrated with oligonucleotide-derivatized gold nanoparticles for a colorimetric detection method. The method enables the specific detection and quantification of unamplified nucleic acid sequences (DNA and RNA) without the need to functionalize the glass surface, allowing for resolution of single nucleotide differences between DNA and RNA sequences-single nucleotide polymorphism and mutation detection. The detector's substrate is glass and the sample is directly applied on the back side of the biosensor, ensuring a direct optical coupling of the assays with a concomitant maximum photon capture and the possibility to reuse the sensor. (c) 2007 American Institute of Physics.

Advances in nanosciences are having a significant impact in many areas of research. The impact of new nanotechnologies has been particularly large in biodiagnostics, where a number of nanoparticle-based assays have been introduced for biomolecules detection. To date, applications of nanoparticles have largely focused on DNA-functionalised gold nanoparticles used as the target-specific probes. These gold nanoparticle-based systems can be used for the detection of specific sequences of DNA (pathogen detection, characterisation of mutation and/or single nucleotide polymorphisms) or RNA (without prior retro-transcription and amplification). Here a rapid and inexpensive nanoparticle-based method for single-base mismatch detection (single nucleotide polymorphism/mutation) in DNA samples is reported. Gold nanoparticles derivatised with thiol modified oligonucleotides complementary to DNA targets - Au-nanoprobes - are used to distinguish fully complementary from mismatched sequences, with a single-base mismatch. The authors have successfully applied this strategy to detect common mutations within the beta-globin gene.

Thiol-linked DNA-gold nanoparticles were used in a novel colorimetric method to detect the presence of specific mRNA from a total RNA extract of yeast cells. The method allowed detection of expression of the FSY1 gene that encodes a specific fructose/H+ symporter in Saccharomyces bayanus PYCC 4565. FSY1 is strongly expressed when the yeast is grown in fructose as the sole carbon source, while cells cultivated in glucose as the sole carbon source repress gene expression. The presence of FSY1 mRNA is detected based on color change of a sample containing total RNA extracted from the organism and gold nanoparticles derivatized with a 15-mer of complementary single stranded DNA upon addition of NaCl. If FSY1 mRNA is present, the solution remains pink, changing to blue-purple in the absence of FSY1 mRNA. Direct detection of specific expression was possible from only 0.3 microg of unamplified total RNA without any further enhancement. This novel method is inexpensive, very easy to perform as no amplification or signal enhancement steps are necessary and takes less than 15 min to develop after total RNA extraction. No temperature control is necessary and color change can be easily detected visually.

Pulmonary hypertension is a significant problem to take into account in the post-operative management of cardiac patients, especially valvular patients. Inhaled nitric oxide allows more effective control of pulmonary pressure and other hemodynamic parameters, with better post-operative results. We present a clinical case of a patient with mitral stenosis and severe pulmonary hypertension, with post-operative hemodynamic instability, in which we used inhaled nitric oxide for better control of pulmonary pressures and to help ventilator weaning.

We present a high-resolution bacterial contig map of 3.4 Mb of genomic DNA in human chromosome 21q11-q21, encompassing the region of elevated disomic homozygosity in Down Syndrome-associated abnormal myelopoiesis and leukemia, as well as the markers, which has shown a strong association with Alzheimer's Disease that has never been explained. The map contains 89 overlapping PACs, BACs, or cosmids in three contigs (850, 850, and 1500 kb) with two gaps (one of 140-210 kb and the second < 5 kb). To date, eight transcribed sequences derived by cDNA selection, exon trapping, and/or global EST sequencing have been positioned onto the map, and the only two genes so far mapped to this cytogenetic region, STCH and RIP140 have been precisely localized. This work converts a further 10% of chromosome 21q into a high-resolution bacterial contig map, which will be the physical basis for the long-range sequencing of this region. The map will also enable positional derivation of new transcribed sequences, as well as new polymorphic probes, that will help in elucidation of the role the genes in this region may play in abnormal myelopoiesis and leukemia associated with trisomy 21 and Alzheimer's Disease.