Diagnosis and management of postrefractive surgery ectasia.

Postrefractive surgery ectasia is a serious, sight-threatening complication seen after the following procedures: laser in situ keratomileusis, photorefractive keratectomy, small-incision lenticule extraction, radial keratotomy, and/or arcuate keratotomy. Specific risk factors may include age, corneal thickness, degree of refractive error, corneal topographic changes including irregular astigmatism, percent tissue ablation, and residual stromal bed. Biomarkers may be a new option to help indicate who is at greatest risk for ectasia. Visual aids including spectacles or contacts lenses are often required to achieve optimal vision. Collagen crosslinking is the only treatment believed to stop progression of ectasia and prevent keratoplasty. Other surgical options may include topography-guided phototherapeutic keratectomy and intrastromal corneal ring segments. Ultimately, an "ounce of prevention is a pound of cure," so careful preoperative screening and ultimately offering the safest and most effective treatments for patients is arguably the most important job of the refractive surgeon.

Congenital Tonic Pupils Associated With Congenital Central Hypoventilation Syndrome and Hirschsprung Disease.

Autonomic dysfunction can be associated with pupillary abnormalities. We describe a rare association of tonic pupils, congenital central hypoventilation syndrome, and Hirschsprung disease in a newborn with a mutation in the PHOX2B gene, a key regulator of neural crest cells. Hirschsprung disease is characterized by the congenital absence of neural crest-derived intrinsic ganglion cells. Tonic pupils may result from an abnormality of the ciliary ganglion, another structure of neural crest origin. The close association of these conditions in this child suggests a common abnormality in neural crest migration and differentiation.

SnapShot-Seq: a method for extracting genome-wide, in vivo mRNA dynamics from a single total RNA sample.

mRNA synthesis, processing, and destruction involve a complex series of molecular steps that are incompletely understood. Because the RNA intermediates in each of these steps have finite lifetimes, extensive mechanistic and dynamical information is encoded in total cellular RNA. Here we report the development of SnapShot-Seq, a set of computational methods that allow the determination of in vivo rates of pre-mRNA synthesis, splicing, intron degradation, and mRNA decay from a single RNA-Seq snapshot of total cellular RNA. SnapShot-Seq can detect in vivo changes in the rates of specific steps of splicing, and it provides genome-wide estimates of pre-mRNA synthesis rates comparable to those obtained via labeling of newly synthesized RNA. We used SnapShot-Seq to investigate the origins of the intrinsic bimodality of metazoan gene expression levels, and our results suggest that this bimodality is partly due to spillover of transcriptional activation from highly expressed genes to their poorly expressed neighbors. SnapShot-Seq dramatically expands the information obtainable from a standard RNA-Seq experiment.

Neuronal expression of TATA box-binding protein containing expanded polyglutamine in knock-in mice reduces chaperone protein response by impairing the function of nuclear factor-Y transcription factor.

The polyglutamine diseases consist of nine neurodegenerative disorders including spinocerebellar ataxia type 17 that is caused by a polyglutamine tract expansion in the TATA box-binding protein. In all polyglutamine diseases, polyglutamine-expanded proteins are ubiquitously expressed throughout the body but cause selective neurodegeneration. Understanding the specific effects of polyglutamine-expanded proteins, when expressed at the endogenous levels, in neurons is important for unravelling the pathogenesis of polyglutamine diseases. However, addressing this important issue using mouse models that either overly or ubiquitously express mutant polyglutamine proteins in the brain and body has proved difficult. To investigate the pathogenesis of spinocerebellar ataxia 17, we generated a conditional knock-in mouse model that expresses one copy of the mutant TATA box-binding protein gene, which encodes a 105-glutamine repeat, selectively in neuronal cells at the endogenous level. Neuronal expression of mutant TATA box-binding protein causes age-dependent neurological symptoms in mice and the degeneration of cerebellar Purkinje cells. Mutant TATA box-binding protein binds more tightly to the transcription factor nuclear factor-Y, inhibits its association with the chaperone protein promoter, as well as the promoter activity and reduces the expression of the chaperones Hsp70, Hsp25 and HspA5, and their response to stress. These findings demonstrate how mutant TATA box-binding protein at the endogenous level affects neuronal function, with important implications for the pathogenesis and treatment of polyglutamine diseases.