Bacteremia after upper gastrointestinal endoscopy.

During 24 months, 200 upper gastrointestinal endoscopies were performed on 193 patients. Blood cultures were obtained before and five and 30 minutes after the procedure using thiol (50 ml) and trypticase soy broth (100 ml) media. The mean endoscopic time was 34 minutes. Sixteen patients developed bacteremia (8%). Twelve groups of microorganisms were detected in positive blood cultures: Streptococcus (5 species), Lactobacillus sp, Veillonella alcalescens, Staphylococcus aureus, Staph epidermidis, Propioni-bacterium acnes, Corynebacterium acnes, and Bacillus subtilis. Seven patients had positive blood cultures at five and 30 minutes, eight at five minutes, and one at 30 minutes only. There was no clear correlation of bacteremia with the age or previous history of the patient, biopsy, active bleeding, endoscopic time, or findings. A follow-up study of all patients for six months to two years indicated no complications related to endoscopy and/or bacteremia.     

Extinction,generalization, and return of fear: A critical review of renewal research in humans

The main behavioral signature of fear extinction is its fragility. This is exemplified by the renewal effect, where a change in the background context produces recovery of fear to a conditioned-and-extinguished stimulus. Renewal is the backbone of a widely accepted theory of extinction in animal research, as well as an important experimental model to screen novel treatment techniques. This has led to an explosion of fear renewal research in humans. However, the mere observation of return of fear in a renewal procedure is not sufficient to validate this particular theory of extinction in the tested sample/procedure. Here, we systematically outline a set of experimental tests that aid in evaluating alternative extinction/renewal mechanisms. We examine published renewal studies in human fear conditioning and conclude that the prevailing theory of extinction is often taken for granted, but critical tests are lacking. Including these tests in future research will not only reveal the fear extinction mechanism in humans, but also inspire further developments in extinction treatment research.