Dependence of the driving force of the sodium pump on rate of transport

The driving force for active transport of Na+ in the isolated toad bladder, ENa, was measured as the reciprocal slope of the change in conductance with change in short-circuit current after stimulation with antidiuretic hormone. The base-line short-circuit current was altered by change in ambient Na+ concentration or addition of amiloride, maneuvers which alter availability of Na+ at the site of active transport. In the absence of a chemical gradient for Na+ across the bladder, ENa was found to be inversely related to the rate of Na+ transport, a finding incompatible with the simple electrical analogue that has been proposed for the system. The results provide additional support for the view that ENa measured in this way has both energetic and kinetic components.     

Surface markers of human eosinophils

Peripheral blood eosinophils from patients with eosinophilia and from healthy subjects were studied for surface immunoglobulins, receptors for the Fc region of IgG, complement receptors, and spontaneous rosette formation with sheep and mouse erythrocytes. Eosinophils were found to have receptors for complement and for aggregated IgG, and to have the same two types of complement receptors as do lymphocytes and monocytes. Immune adherence type receptors were specific for C4 or C3b, while C3d receptors were specific for C3d but unreactive with C4. Eosinophils differed from fully mature neutrophils in that the former had C3d receptors and relatively weak immune adherence (C4 or C3b) receptors, while the later did not have the C3d receptors and had strong immune adherence receptors. Eosinophil phagocytosis of complement-receptor bound erythrocytes was dependent on the presence of IgG in the antibody coating the red blood cells; this requirement for IgG resembled that found in neutrophil phagocytosis. No surface Ig or spontaneous erythrocyte rosette formation was observed with eosinophils.     

Comparison of methods for identifying transcription units and transcription map of the Werner syndrome gene region

OBJECTIVE: The audiologic presentation of vestibular schwannoma (VS) associated with neurofibromatosis type 2 (NF2) has not been well characterized. The goal of this study was to investigate the audiologic features of NF2-associated VS and to determine their relationship to the size of the tumor. STUDY DESIGN: A retrospective case review. SETTING: Quaternary governmental medical research institute evaluating patients fitting specific criteria for ongoing clinical studies. PATIENTS: Audiologic and magnetic resonance imaging data were available for 40 patients (25 males, 15 females), with an average age of 32 years, who had been recruited for ongoing clinical and genetic studies of NF2. MAIN OUTCOME MEASURES: The audiologic profile and magnetic resonance imaging characteristic of tumor were retrospectively reviewed. RESULTS: The average size of the tumor at presentation was 7.26 +/- 16.58 cm3 and measured 1.2, 1.6, and 1.1 cm in the anterior/posterior, lateral/medial, and superior/inferior dimensions, respectively. An increase in lateral/medial size of the tumor most significantly correlated with deterioration in mid- (1,000-2,000 Hz) and high- (4,000-8,000 Hz) frequency hearing levels, elevated speech reception threshold, and prolonged auditory brain stem response waves III and V latency. CONCLUSIONS: Patients with NF2 demonstrate a more predictable audiologic profile for a given size tumor than has been previously described with spontaneous or sporadic VS.