The Vps4p AAA ATPase regulates membrane association of a Vps protein complex required for normal endosome function

Vps4p is an AAA-type ATPase required for efficient transport of biosynthetic and endocytic cargo from an endosome to the lysosome-like vacuole of Saccharomyces cerevisiae. Vps4p mutants that do not bind ATP or are defective in ATP hydrolysis were characterized both in vivo and in vitro. The nucleotide-free or ADP-bound form of Vps4p existed as a dimer, whereas in the ATP-locked state, Vps4p dimers assembled into a decameric complex. This suggests that ATP hydrolysis drives a cycle of association and dissociation of Vps4p dimers/decamers. Nucleotide binding also regulated the association of Vps4p with an endosomal compartment in vivo. This membrane association required the N-terminal coiled-coil motif of Vps4p, but deletion of the coiled-coil domain did not affect ATPase activity or oligomeric assembly of the protein. Membrane association of two previously uncharacterized class E Vps proteins, Vps24p and Vps32p/Snf7p, was also affected by mutations in VPS4. Upon inactivation of a temperature-conditional vps4 mutant, Vps24p and Vps32p/Snf7p rapidly accumulated in a large membrane-bound complex. Immunofluorescence indicated that both proteins function with Vps4p at a common endosomal compartment. Together, the data suggest that the Vps4 ATPase catalyzes the release (uncoating) of an endosomal membrane-associated class E protein complex(es) required for normal morphology and sorting activity of the endosome.     

Is there a place for hospitalists in health-care reform?

A case of stone heart syndrome is reported in a pregnant 27 year old West African patient, who suffered syncopal symptoms shortly before cardiac arrest. The electrocardiographic features were those of asystole, but direct examination of the heart at emergency thoracotomy in the A&E department revealed tetanic contracture of the organ. At necropsy, the heart was of normal weight but showed areas of fibrosis surrounding the bundle of His. The discrepancy between the ECG features and the physiological state of the heart raises the possibility that other cases of apparent asystole may not be what they seem.     

Pulmonary vasculitis

Pulmonary vascular inflammation may be seen in a variety of primary lung diseases and in the setting of numerous systemic illnesses. This article reviews those entities in which pulmonary vasculitis represents a central feature of the pathologic process (Wegener's granulomatosis, Churg-Strauss syndrome, and pulmonary capillaritis). In addition, features of pulmonary involvement in other systemic vasculitides (Giant Cell Arteritis, Takayasu's Arteritis, and Beh?et's disease) are described. Finally, general principles for the treatment of vasculitis are reviewed.     

Meeting the educational needs of patients with oral lichen planus

Lichen planus is a chronic oral disorder that is often painful and annoying. The patients have been described as usually over 50 years old, with a high educational level, anxious and high-strung. In previous research studies, these patients have reported unusual and highly stressful life events. Because dentists are in a position to advise their patients about chronic illness, this study was designed to (1) determine what information was given to lichen planus patients by their dentists; (2) determine what questions the patients asked their dentists; and (3) assess what educational materials would be helpful for this group of patients. A survey was sent to 151 biopsy-confirmed lichen planus patients, with a response rate of 55 percent. The results indicated that the patients were concerned about the possibility of malignancy and of contagion, and that they were frustrated by the lack of available patient education.     

Chalazion-induced hyperopia as a cause of decreased vision

This article presents three cases of decreased vision due to acquired hyperopia, which were caused by a chalazion of the upper eyelid. Through manifest refraction and computerized corneal topographic analysis, acquired hyperopia associated with central corneal flattening was revealed. These findings were responsible for the blurred vision that was reversed by chalazion resolution or removal. Although not usually considered a risk factor for refractive disorders other than astigmatism, chalazia of the upper eyelid can present as a decrease in vision associated with reversible central corneal flattening and acquired hyperopia.