Antibiotic treatment alters the colonic mucus layer and predisposes the host to exacerbated Citrobacter rodentium-induced colitis.

Antibiotics are often used in the clinic to treat bacterial infections, but the effects of these drugs on microbiota composition and on intestinal immunity are poorly understood. Citrobacter rodentium was used as a model enteric pathogen to investigate the effect of microbial perturbation on intestinal barriers and susceptibility to colitis. Streptomycin and metronidazole were used to induce alterations in the composition of the microbiota prior to infection with C. rodentium. Metronidazole pretreatment increased susceptibility to C. rodentium-induced colitis over that of untreated and streptomycin-pretreated mice, 6 days postinfection. Both antibiotic treatments altered microbial composition, without affecting total numbers, but metronidazole treatment resulted in a more dramatic change, including a reduced population of Porphyromonadaceae and increased numbers of lactobacilli. Disruption of the microbiota with metronidazole, but not streptomycin treatment, resulted in an increased inflammatory tone of the intestine characterized by increased bacterial stimulation of the epithelium, altered goblet cell function, and thinning of the inner mucus layer, suggesting a weakened mucosal barrier. This reduction in mucus thickness correlates with increased attachment of C. rodentium to the intestinal epithelium, contributing to the exacerbated severity of C. rodentium-induced colitis in metronidazole-pretreated mice. These results suggest that antibiotic perturbation of the microbiota can disrupt intestinal homeostasis and the integrity of intestinal defenses, which protect against invading pathogens and intestinal inflammation.

Multicomponent treatment for blood-injury-injection phobia in a young man with mental retardation.

Blood-Injury-Injection Phobia (BIIP) is a subtype of specific phobia, characterized by fear and avoidance of seeing blood, an injury, or receiving an injection. In the current case report, we describe the treatment of BIIP in a young man with mental retardation. The multicomponent treatment consisted of fading (graduated exposure), modeling, noncontingent and differential reinforcement, presession anxiolytic medication, and topical analgesic cream.

The effects of response cost in the treatment of aberrant behavior maintained by negative reinforcement.

Positive reinforcement contingencies can sometimes be used to decrease problem behavior maintained by negative reinforcement (e.g., escape). In the current study, we evaluated the extent to which response cost (i.e., contingent removal of a preferred stimulus) would compete with the negative reinforcer maintaining destructive behavior. The response cost contingency reduced destructive behavior by 87% from baseline levels even though the negative reinforcement contingency (i.e., escape) remained in place.

Treatment of pica through multiple analyses of its reinforcing functions.

We conducted functional analyses of the pica of 3 participants. The pica of 1 participant appeared to be maintained by automatic reinforcement; that of the other 2 participants appeared to be multiply controlled by social and automatic reinforcement. Subsequent preference and treatment analyses were used to identify stimuli that would complete with the automatic function of pica for the 3 participants. These analyses also identified the specific aspect of oral stimulation that served as automatic reinforcement for 2 of the participants. In addition, functional analysis-based treatments were used to address the socially motivated components of 2 of the participants' pica. Results are discussed in terms of (a) the importance of using the results of functional analyses to develop treatments for pica and (b) the advantages of developing indirect analyses to identify specific sources of reinforcement for automatically reinforced behavior.

Effects of wrist weights on self-injurious and adaptive behaviors.

The effects of wrist weights on the self-injurious and adaptive behaviors of a young boy with profound mental retardation were evaluated. Application of wrist weights reduced SIB by 92% and was associated with either increases or stable levels of multiple novel and preexisting adaptive behaviors.