The Potential and Challenges of Nanopore Sequencing

A nanopore-based device provides single-molecule detection and analytical capabilities that are achieved by electrophoretically driving molecules in solution through a nano-scale pore. The nanopore provides a highly confined space within which single nucleic acid polymers can be analyzed at high throughput by one of a variety of means, and the perfect processivity that can be enforced in a narrow pore ensures that the native order of the nucleobases in a polynucleotide is reflected in the sequence of signals that is detected. Kilobase length polymers (single-stranded genomic DNA or RNA) or small molecules (e.g., nucleosides) can be identified and characterized without amplification or labeling, a unique analytical capability that makes inexpensive, rapid DNA sequencing a possibility. Further research and development to overcome current challenges to nanopore identification of each successive nucleotide in a DNA strand offers the prospect of ‘third generation’ instruments that will sequence a diploid mammalian genome for ~$1,000 in ~24 h.Molecular and Cellular BiologyPhysic

Penicillamine-associated cutis laxa and milia en plaque - case report and review of cutaneous changes associated with penicillamine

Penicillamine-induced skin changes are rare and include: hypersensitivity reactions, autoimmune reactions, and cutaneous elastoses. We report a case of a 73-year-old man with cystinuria taking penicillamine for over 50 years who presented with penicillamine-induced cutis laxa and milia en plaque. A brief review of penicillamine induced skin changes, specifically cutis laxa and milia en plaque, is presented

Tonsillectomy as a treatment for psoriasis: A review

Psoriasis is a chronic skin disorder that affects 1% to 3% of the general population worldwide. Streptococcal infection, especially streptococcal pharyngitis, has been shown to be a significant trigger of psoriasis in some patients, possibly by sensitizing T cells to keratin epitopes in the skin. Due to the role of the palatine tonsils as an immunological organ that may generate autoreactive T cells, tonsillectomy has been investigated as a treatment for psoriasis. Tonsillectomy originally gained acceptance in Japan as a treatment for palmoplantar pustulosis, a condition that shares features with pustular psoriasis. Subsequently, tonsillectomy has been used for the treatment of plaque psoriasis and guttate psoriasis. Recently, the first randomized, controlled clinical trial of tonsillectomy was performed. Here, we review the available evidence for the benefit of tonsillectomy as a treatment for palmoplantar pustulosis and psoriasis. We also discuss molecular studies aimed at understanding the role of tonsils in skin disease

Origins and Consequences of Velocity Fluctuations during DNA Passage through a Nanopore

We describe experiments and modeling results that reveal and explain the distribution of times that identical double-stranded DNA (dsDNA) molecules take to pass through a voltage-biased solid-state nanopore. We show that the observed spread in this distribution is caused by viscous-drag-induced velocity fluctuations that are correlated with the initial conformation of nanopore-captured molecules. This contribution exceeds that due to diffusional Brownian motion during the passage. Nevertheless, and somewhat counterintuitively, the diffusional Brownian motion determines the fundamental limitations of rapid DNA strand sequencing with a nanopore. We model both diffusional and conformational fluctuations in a Langevin description. It accounts well for passage time variations for DNA molecules of different lengths, and predicts conditions required for low-error-rate nanopore-strand DNA sequencing with nanopores