Conditioned suppression tests of the context-blocking hypothesis: Testing in the absence of the preconditioned context.

A conditioned-suppression procedure was used in 2 studies, with 96 male albino rats, to test the context-blocking hypothesis, the proposition that static apparatus cues, or conditioning contexts, can block conditioning to discrete CSs. Exp I tested for conditioning to the target CS in the same context that had been preconditioned and in which target conditioning had occurred. A context-blockinglike effect was demonstrated. Exp II tested for conditioning not only in the preconditioned context but also in a nonpreconditioned context. Exp II results are consistent with the idea that associative conditioning to a discrete target CS is not independent of the conditioned strength of the context in which target conditioning occurs. Evidence for context blocking was similar in the 2 studies, suggesting that conditioned contexts block the acquisition of associative strength by discrete CSs at the time of target conditioning and not through performance factors at the time of testing. (45 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

A survey of 14 computed tomography scanners in Greece and 32 scanners in Italy. Examination frequencies,dose reference values,effective doses and doses to organs

A survey of examination frequencies, dose reference values, effective doses and doses to organs involving 14 scanners from Greece and 32 scanners from Italy was carried out for the years 1999 and 2000. Examination frequencies per scanner and per year were found to be 3590 for Greece and 4520 for Italy. For the types of examinations considered, CDTI(W) and DLP measurements were taken. Also scan lengths used for the same types of examinations were monitored. For the same types of examinations effective doses were calculated by two methods, and it was found that their mean values ranged from 13.1 mSv for thoracic spine to 1.6 mSv for the brain examinations. From the data of the 14 Greek laboratories, doses to organs were calculated and it was found that the thyroid receives 50.2 +/- 19.8 mGy during a cervical spine examination while the gonads receive 17.8 +/- 6.9 mGy during a routine pelvis examination.     

Effect of naloxone on conditioned suppression in rats.

Painful stimuli are known to engage an endorphin analgesic system that can be reversed by the opiate antagonist, naloxone. Naloxone, then, should increase the effectiveness of aversive unconditioned stimulus/stimuli (UCS) in Pavlovian fear conditioning. Consistent with this hypothesis, naloxone administered during the acquisition of conditioned suppression in rats enhanced posttrial suppression and preconditioned stimulus (pre-CS; context-controlled) suppression. Furthermore, it enhanced CS-elicited suppression during extinction when administered during acquisition but not when administered only during extinction. Thus naloxone does not enhance an already existing fear nor enhance the memory of previous conditioning; instead, it enhances the conditioning of fear presumably by making the aversive UCS more painful. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Signaled tailshock is perceived as similar to a stronger unsignaled tailshock: Implications for a functional analysis of classical conditioning.

24 water-deprived male Sprague-Dawley albino rats given fixed-electrode, variable-intensity tailshock at random times rated each trial by pressing either a "high-aversiveness" or "low-aversiveness" lever to obtain water. Trials on which a warning signal preceded tailshock resulted in more "high-aversiveness" leverpressing than did unsignaled trials. The magnitude of this effect varied as a function of factors including signal–shock interval, signal duration, and range and absolute value of shock intensities. Efforts to achieve a reversal of this effect were unsuccessful. Results suggest that the effect of the signal on lever choice was due largely to the aversiveness of the signal summating with the aversiveness of the tailshock. Hypotheses concerning factors that might have either masked or prevented classically conditioned preparatory responses elicited by the signal from reducing tailshock aversiveness were tested and rejected. Despite the greater aversiveness of the signaled condition, when given a choice of receiving or not receiving the signal, Ss displayed a preference for signaled tailshock. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lanthionine,a Novel Uremic Toxin,in the Vascular Calcification of Chronic Kidney Disease: The Role of Proinflammatory Cytokines

Vascular calcification (VC) is a risk factor for cardiovascular events and mortality in chronic kidney disease (CKD). Several components influence the occurrence of VC, among which inflammation. A novel uremic toxin, lanthionine, was shown to increase intracellular calcium in endothelial cells and may have a role in VC. A group of CKD patients was selected and divided into patients with a glomerular filtration rate (GFR) of <45 mL/min/1.73 m² and ≥45 mL/min/1.73 m². Total Calcium Score (TCS), based on the Agatston score, was assessed as circulating lanthionine and a panel of different cytokines. A hemodialysis patient group was also considered. Lanthionine was elevated in CKD patients, and levels increased significantly in hemodialysis patients with respect to the two CKD groups; in addition, lanthionine increased along with the increase in TCS, starting from one up to three. Interleukin IL-6, IL-8, and Eotaxin were significantly increased in patients with GFR < 45 mL/min/1.73 m² with respect to those with GFR ≥ 45 mL/min/1.73 m². IL-1b, IL-7, IL-8, IL-12, Eotaxin, and VEGF increased in calcified patients with respect to the non-calcified. IL-8 and Eotaxin were elevated both in the low GFR group and in the calcified group. We propose that lanthionine, but also IL-8 and Eotaxin, in particular, are a key feature of VC of CKD, with possible marker significance.