Subtle gastric abnormalities in a canine model: detection with low-dose imaging with storage phosphors and its equivalence to conventional radiography

The authors compared low-dose (32% of standard exposure) storage phosphor digital imaging (system resolution: 0.2-mm pixels, 10 bits) with isovoltage 75-kVp conventional radiography (standard exposure) in the detection of subtle simulated gastric abnormalities by using air contrast barium studies. Subtle simulated abnormalities (3-7-mm polyps, 4-15-mm ulcer craters, 4-11-mm-diameter edema, and 11-12-mm linear ulcers) were produced in resected canine stomachs. Receiver operating characteristic analysis of 1,800 observations by six readers indicated that the digital images with and without high-frequency edge enhancement were equivalent to conventional radiographs (mean receiver operating characteristic areas [+/- standard deviation]: 0.76 +/- 0.06, 0.78 +/- 0.04, and 0.77 +/- 0.04, respectively). The accuracy of the diagnosis was equivalent for all three modalities. The following mean accuracies of negative and positive responses, respectively, for unenhanced digital, edge-enhanced digital, and conventional images were determined: 0.71 +/- 0.05 and 0.41 +/- 0.07, 0.71 +/- 0.04 and 0.51 +/- 0.09, and 0.68 +/- 0.04 and 0.43 +/- 0.05. It was concluded that low-dose storage phosphor air-contrast barium studies were equivalent to conventional radiography in the detection of subtle gastric abnormalities.     

Actinomyces meyeri actinomycosis: a case with thoracic and tibial localization

Apart from the rarity of the causal agent, this case is of interest because of the absence of cervico-facial involvement and the presence of multiple cutaneous nodules at a distance from the visceral localisation.     

Membrane–cytoskeleton interactions during the formation of the immunological synapse and subsequent T-cell activation

Summary: Upon antigen recognition, T cells undergo substantial membrane and cytoskeletal rearrangements that lead to the formation of the immunological synapse and are necessary for subsequent T‐cell activation. However, little is known about how membrane and cytoskeletal molecules interact during these processes. Here we discuss the involvement of the membrane‐microfilament linker ezrin. We propose that ezrin is a component of the cytoskeleton‐mediated architecture of the immunological synapse that plays a role in T‐cell receptor clustering, protein kinase C θ translocation and intracellular signaling.     

Effects of verapamil and nifedipine on mechanisms of arrhythmia in an in vitro model of ischemia and reperfusion.

The effects of verapamil and nifedipine on cellular mechanisms of arrhythmia were examined in isolated canine Purkinje fiber-papillary muscles. Microelectrode recordings were made simultaneously from both tissues. Preparations were superfused with Tyrode's solution modified to mimic specific conditions of ischemia for 40 min with or without calcium channel blockers. Verapamil or nifedipine resulted in significantly greater depolarization of Purkinje tissue in response to ischemic conditions and increased the incidence of inexcitability or conduction block in Purkinje and muscle tissues. These calcium channel blockers caused only minor changes in ischemia-induced depolarization of muscle. In Purkinje tissue, return to nonischemic conditions in the absence of drugs caused, in sequence, oscillatory afterpotentials, temporary depolarization to inexcitability, and a phase of automaticity at low membrane potential. These events did not occur in muscle. Verapamil or nifedipine abolished oscillatory afterpotentials and low membrane potential automaticity in Purkinje tissue. However, reperfusion-induced depolarization and inexcitability of Purkinje tissue was delayed but not attenuated. This study demonstrates that verapamil or nifedipine exacerbate depolarization and depression of conduction in Purkinje tissue exposed to ischemic conditions. However, verapamil and nifedipine suppress some but not all potential mechanisms of arrhythmia induced by reperfusion.     

The impact of CON regulation on hospital efficiency

In this paper we propose an empirically implementable measure of aggregate-level efficiency along the lines of Debreu’s (1951) coefficient of resource utilization but restricted to the production side. The efficiency measure is based on directional distance functions, which allows the overall measure of efficiency to be decomposed into measures of technical and “structural” efficiency. The latter measure, which captures inefficiencies associated with the organization of production within an industry, is further decomposed into measures of scale and mix efficiency. The measures developed in the paper are illustrated using U.S. hospital data. The illustration sheds light on the efficacy of certificate of need (CON) regulations.     

Neuronal re-uptake of noradrenaline by sympathetic nerves in humans.

1. Plasma concentrations of [3H]dihydroxyphenylglycol, the intraneuronal metabolite of noradrenaline, were examined during intravenous infusion of [3H]noradrenaline in 43 subjects, to assess the nature of its formation. Noradrenaline re-uptake by sympathetic nerves was estimated in 11 subjects from the effects of neuronal uptake blockade with desipramine on noradrenaline clearance and plasma concentrations of [3H]dihydroxyphenylglycol and endogenous dihydroxyphenylglycol. In seven subjects noradrenaline re-uptake and spillover into plasma were examined before and during mental arithmetic or handgrip exercise. 2. During infusion of [3H]noradrenaline, plasma [3H]dihydroxyphenylglycol increased progressively, indicating its formation from previously stored [3H]noradrenaline leaking from vesicles as well as from [3H]noradrenaline metabolism immediately after removal into sympathetic nerves. Thus, to estimate noradrenaline re-uptake, the amount of [3H]dihydroxyphenylglycol derived from [3H]noradrenaline metabolized immediately after removal into the sympathetic axoplasm must be isolated from that derived from [3H]noradrenaline sequestered into vesicles. 3. At rest in the supine position the rate of noradrenaline re-uptake was 474 +/- 122 pmol min-1 kg-1, 9.5-fold higher than the rate of spillover of noradrenaline into plasma (49.6 +/- 6.4 pmol min-1 kg-1). Noradrenaline re-uptake and spillover into plasma were both increased during mental arithmetic and isometric handgrip exercise.