Portal venous gas as a radiological sign in a sigmoid diverticular abscess and its non-surgical management: a case report.

A 62-year old man who presented unwell with no specific symptoms or signs was found to have portal venous circulation gas complicating a small diverticular abscess. He was successfully managed with a course of antibiotics and had full resolution of symptoms, therefore avoiding the need for surgical intervention. While most commonly associated with bowel ischaemia and therefore often warranting emergency laparotomy, portal venous gas within the context of other underlying pathology often presents opportunities for delayed surgery or more conservative management options.

Delayed and persistent suppression of bronchoconstriction by trypsin in the airway lumen.

Mucosal trypsin, a protease-activated receptor (PAR) stimulant, may have an endogenous bronchoprotective role on airway smooth muscle. To test this possibility the effects of lumenal trypsin on airway tone in segments of pig bronchus were tested. Bronchial segments from pigs were mounted in an organ chamber containing Kreb's solution. Contractions were assessed from isovolumetric lumen pressure induced by acetylcholine (ACh) or carbachol added to the adventitia. Trypsin, added to the airway lumen (300 microg x mL(-1)), had no immediate effect on smooth muscle tone but suppressed ACh-induced contractions after 60 min, for at least 3 h. Synthetic activating peptides (AP) for PAR1, PAR2 or PAR3 were without effect, but PAR4 AP caused rapid, weak suppression of contractions. Lumenal thrombin was without effect and did not prevent the effects of trypsin. Effects of trypsin were reduced by N(omega)-nitro-L-arginine methyl ester but not indomethacin. Trypsin, thrombin and PAR4 AP released prostaglandin E2. Adventitially, trypsin, thrombin and PAR4 AP (but not PAR2 AP) relaxed carbachol-toned airways after <3 min. The findings of this study show that trypsin causes delayed and persistent bronchoprotection by interacting with airway cells accessible from the lumen. The signalling mechanism may involve nitric oxide synthase but not prostanoids or protease-activated receptors.

Treatment of multiply controlled destructive behavior with food reinforcement.

We evaluated the extent to which the positive reinforcement of communication would reduce multiply controlled destructive behavior in the absence of relevant extinction components. When edible reinforcement for appropriate communication and nonfood reinforcers for problem behavior were available simultaneously, responding was allocated almost exclusively toward the behavior that produced edible reinforcement.

Competition between noncontingent and contingent reinforcement schedules during response acquisition.

We examined the extent to which noncontingent reinforcement (NCR), when used as treatment to reduce problem behavior, might interfere with differential reinforcement contingencies designed to strengthen alternative behavior. After conducting a functional analysis to identify the reinforcers maintaining 2 participants' self-injurious behavior (SIB), we delivered those reinforcers under dense NCR schedules. We delivered the same reinforcers concurrently under differential-reinforcement-of-alternative-behavior (DRA) contingencies in an attempt to strengthen replacement behaviors (mands). Results showed that the NCR plus DRA intervention was associated with a decrease in SIB but little or no increase in appropriate mands. In a subsequent phase, when the NCR schedule was thinned while the DRA schedule remained unchanged, SIB remained low and mands increased. These results suggest that dense NCR schedules may alter establishing operations that result in not only suppression of problem behavior but also interference with the acquisition of appropriate behavior. Thus, the strengthening of socially appropriate behaviors as replacements for problem behavior during NCR interventions might best be achieved if the NCR schedule is first thinned.

An evaluation of the effects of matched stimuli on behaviors maintained by automatic reinforcement.

The purpose of the current investigation was to extend the literature on matched stimuli to three dissimilar forms of aberrant behavior (dangerous climbing and jumping, saliva manipulation, and hand mouthing). The results of functional analyses suggested that each behavior was automatically reinforced. Preference assessments were used to identify two classes of stimuli: items that matched the hypothesized sensory consequences of aberrant behavior (matched stimuli) and items that produced sensory consequences that were not similar to those produced by the aberrant behavior (unmatched stimuli). The effects of providing continuous and noncontingent access to either the most highly preferred matched or the most highly preferred unmatched stimuli were assessed relative to a condition in which no stimuli were available. Overall results suggested that providing access to items that matched the hypothesized sensory consequences of aberrant behavior may be more effective than simply selecting stimuli either arbitrarily or based on the results of preference assessments alone.

Multicomponent assessment and treatment of cigarette pica.

We conducted a multicomponent assessment and treatment for 4 individuals who engaged in cigarette pica. During Phase 1, three stimulus preference assessments were conducted to identify (a) the reinforcing component of the cigarette, (b) potential alternative reinforcers that may be used during treatment, and (c) whether the alternative reinforcer would compete effectively with cigarettes. Results were successful in identifying the reinforcing component of the cigarette and suggested the feasibility of using alternative reinforcers during treatment to eliminate cigarette pica. During Phase 2, the effects of two treatment procedures were evaluated. Noncontingent reinforcement (NCR) with the alternative edible reinforcer reduced the pica of 2 of the participants, but effects were not maintained when the initial dense schedule of NCR was thinned. Subsequently, differential reinforcement of alternative behavior with the alternative edible reinforcer was effective in reducing pica for 3 participants. An evaluation of nine treatment procedures failed to identify an effective intervention for the remaining participant; consequently, preventive measures were designed to minimize occurrences of cigarette pica.

An evaluation of the properties of attention as reinforcement for destructive and appropriate behavior.

The analogue functional analysis described by Iwata, Dorsey, Slifer, Bauman, and Richman (1982/1994) identifies broad classes of variables (e.g., positive reinforcement) that maintain destructive behavior (Fisher, Ninness, Piazza, & Owen-DeSchryver, 1996). However, it is likely that some types of stimuli may be more effective reinforcers than others. In the current investigation, we identified 2 participants whose destructive behavior was maintained by attention. We used concurrent schedules of reinforcement to evaluate how different types of attention affected both destructive and appropriate behavior. We showed that for 1 participant praise was not an effective reinforcer when verbal reprimands were available; however, praise was an effective reinforcer when verbal reprimands were unavailable. For the 2nd participant, we identified a type of attention that effectively competed with verbal reprimands as reinforcement. We then used the information obtained from the assessments to develop effective treatments to reduce destructive behavior and increase an alternative communicative response.

A comparison of noncontingent reinforcement and sensory extinction as treatments for self-injurious behavior.

We compared the effects of two treatments, noncontingent reinforcement (NCR) and sensory extinction (EXT), on the self-injurious behavior (SIB) exhibited by 3 individuals with developmental disabilities. Results of a functional analysis indicated that their SIB was not maintained by social reinforcement, as indicated by undifferentiated responding across assessment conditions or higher rates of responding in the along condition. Prior to treatment, leisure probes were conducted to identify highly preferred items for use in the NCR condition, and equipment probes were conducted to identify devices that produced the greatest behavioral suppression for use in the EXT condition. Following baseline, treatment was implemented in a multiple baseline across subjects design, and the effects of NCR and EXT were compared in a multielement format. During NCR sessions, participants had continuous access to a highly preferred item. During EXT sessions, participants wore equipment (gloves or protective sleeves) that seemed to attenuate stimulation directly produced by their SIB, while still allowing the behavior to occur. Results indicated that both procedures were effective in reducing SIB, although NCR was associated with either more rapid or greater overall response suppression.

Emergence of reinforcer preference as a function of schedule requirements and stimulus similarity.

Tustin (1994) recently observed that an individual's preference for one of two concurrently available reinforcers under low schedule requirements (concurrent fixed-ratio [FR] 1) switched to the other reinforcer when the schedule requirements were high (concurrent FR 10). We extended this line of research by examining preference for similar and dissimilar reinforcers (i.e., those affecting the same sensory modality and those affecting different sensory modalities). Two individuals with developmental disabilities were exposed to an arrangement in which pressing two different panels produced two different reinforcers according to progressively increasing, concurrent-ratio schedules. When two dissimilar stimuli were concurrently available (food and a leisure item), no clear preference for one item over the other was observed, regardless of the FR schedules in effect (FR 1, 2, 5, 10, and 20). By contrast, when two similar stimuli were concurrently available (two food items), a clear preference for one item emerged as the schedule requirements were increased from FR 1 to FR 5 or FR 10. These results are discussed in terms of implications for conducting preference assessments and for selecting reinforcers to be used under training conditions in which response requirements are relatively high or effortful.

An analysis of the reinforcing properties of hand mouthing.

Hand mouthing often has been described as a stereotypic response that is maintained by nonsocial (automatic) reinforcement; however, data supporting this conclusion can be found in relatively few studies. This series of studies presents an experimental analysis of conditions associated with the maintenance of hand mouthing. In Experiment 1, a functional analysis was conducted for 12 individuals who engaged in chronic hand mouthing, to determine whether the behavior is usually maintained independent of social contingencies. Results obtained for 10 subjects were consistent with an automatic reinforcement hypothesis; the remaining 2 subjects' hand mouthing was maintained by social-positive reinforcement. Based on these results, Experiment 2 was designed to identify the specific reinforcing properties of hand mouthing. Each of 4 subjects was provided with a toy that substituted for hand mouthing, and preference for a specific topography of toy manipulation (hand-toy contact or mouth-toy contact) was measured. Results indicated that hand stimulation was the predominant reinforcer for all subjects. Experiment 3 provided an extension of Experiment 2 in that the same responses were measured across a variety of toys presented to each of 5 subjects. Results again indicated that hand stimulation was the predominant reinforcer for all subjects. Implications of these results are discussed with relevance to treatment.

Behavioral persistence and variability during extinction of self-injury maintained by escape.

The self-injurious escape behavior of a developmentally disabled adult was treated with extinction. Results of a reversal design showed substantial bursts of responding when extinction was introduced and reintroduced: self-injury remained at a variable and elevated rate for some time before stable, low rates were observed. Data on aggression, a nontarget behavior during both baseline and treatment, showed a pattern similar to that seen for self-injury during the extinction conditions.