BACKGROUND Benign paroxysmal positional vertigo is a common and treatable vestibular disorder characterized by attacks of positional vertigo. Although elderly patients often complain about unsteadiness, the symptom of positional vertigo is seldom reported. Several studies on BPPV in the elderly reveal a low success rate in the treatment of this entity. OBJECTIVES To assess the clinical charac...

BACKGROUND The light cupula is a condition wherein the cupula of the semicircular canal has a lower specific gravity than its surrounding endolymph. It is characterized by a persistent geotropic direction-changing positional nystagmus in the supine head-roll test, and the identification of a null plane with slight head-turning to either side. CASE PRESENTATION This study describes a case of r...

The genetic basis of morphological differences among species is still poorly understood. We investigated the genetic basis of sex-specific differences in wing size between two closely related species of Nasonia by positional cloning a major male-specific locus, wing-size1 (ws1). Male wing size increases by 45% through cell size and cell number changes when the ws1 allele from N. giraulti is bac...

The use of positional cloning for the identification of complex trait susceptibility genes has gained momentum with the completion of the human genome project. The approach involves the collection of well-phenotyped cohorts (either family-based or case-control designs), the generation of high-density single-nucleotide polymorphism linkage disequilibrium maps, and the application of powerful sta...

A two-gradient model is proposed for regulation and regeneration of the head end of hydra in terms of positional information. One gradient is set up by a diffusible substance made at the head end, which may be regarded as a positional signal, and the other is a more stable cellular parameter which is the positional value. The rule for head end formation is that the concentration of the diffusib...