Flavor preference conditioning by oral self-administration of ethanol

 Oral self-administration and operant tasks have been used successfully to confirm ethanol′s positive reinforcing effects in rats. However, in flavor conditioning tasks, ethanol is typically found to have aversive effects. The present studies explored this apparent paradox by examining the change in value of a flavor paired with orally self-administered ethanol in two different limited-access procedures. Rats were food-deprived and trained to drink (experiment 1) or to barpress for (experiment 2) 10% (v/v) ethanol during daily 30-min sessions using prandial initiation techniques. All rats were then exposed to a differential flavor conditioning procedure in which banana or almond extract was added to the drinking solution. One flavor (counterbalanced) was always mixed with ethanol (CS+), whereas the other flavor was mixed with water (CS–). By the end of conditioning, rats in both experiments drank more flavored ethanol than flavored water, confirming ethanol’s efficacy as a reinforcer. Moreover, barpress rates for CS+ exceeded those for CS– in the operant task. Ethanol doses self-administered in final sessions averaged about 1 g/kg. The effect of the flavor-ethanol contingency was assessed in preference tests that offered a choice between the two flavor solutions without ethanol. In both experiments, subjects developed a preference for the flavor that had been paired with ethanol. Thus, the outcome of flavor conditioning was consistent with that of the oral self-administration tasks in providing evidence of ethanol’s rewarding effects. These experiments confirm and extend previous studies showing that flavor aversion is not the inevitable result of flavor-ethanol association in rats. It seems likely that ethanol’s nutrient and pharmacological effects both contributed to the development of conditioned flavor preference. Received: 15 February 1997 / Final version: 11 June 1997     

Choroidal lesions in patients with AIDS.

Seven cases of bilateral, scattered, yellow-white choroidal lesions have been seen in AIDS patients since January 1988. One resulted from presumed extension of cryptococcal meningitis into the optic nerve and choroid. All the remaining six patients had pneumocystis pneumonia at some time during the course of the disease and were receiving aerosolised pentamidine therapy. None died quickly of disseminated Pneumocystis carinii infection, unlike previously reported patients. Mycobacterial infection was also present in five of these six patients. The differential diagnosis of this entity in AIDS patients is discussed.     

The Workup for Bariatric Surgery Does Not Require a Routine Upper Gastrointestinal Series

Background: Morbid obesity is a serious disease that afflicts over five million Americans, threatening their health with such co-morbidities as diabetes, arthritis, pulmonary failure and stroke. Surgery is the only effective therapy, providing long-term control of weight, diabetes, pulmonary failure, and hypertension for as long as 14 years. Because the operation presents a major expense, this study examined whether X-ray examination of the gut could be omitted safely as a cost-saving measure. Methods: The records of 814 consecutive morbidly obese patients who underwent gastric bypass were reviewed to determine: (1) whether these individuals had undergone an upper gastro-intestinal (GI) series, and (2) if these studies influenced therapy or caused cancellation or postponement of surgery. Results: Of the 814 patients, 657 (80.7%) underwent a preoperative GI radiography. Of these examinations, 393 (59.8%) were normal, with the following abnormalities in the remaining 264: hiatal hernia, 164; esophageal reflux, 39; Schatzki's ring, 18; small bowel diverticula, four; renal stones, four; malrotation, three; gall stones, two; pyloric ulcer, one; possible pelvic mass, one; calcified leiomyoma, one; and dysphagial lusoria, one. None of these findings resulted in cancellation or a delay in surgery. Conclusions: The upper GI series can be safely omitted from the routine preoperative evaluation of patients undergoing gastric bypass. At a cost of $741.00 per examination, this change represents significant potential savings. Similar evaluations of other routine preoperative tests may well provide a better basis for the evaluation of these complex patients.     

Sensations during chest tube removal

Nurses prepare patients for chest tube removal, yet little has been written to indicate the sensations to be expected during this routine procedure. The sensations reported by patients and factors that could influence those sensations were examined in this study. The sample consisted of 36 patients after thoracic surgery (24 men and 12 women), all of whom were scheduled to have either a mediastinal or a pleural tube removed. They reported their sensations and the intensity of those sensations (using a 100 mm visual analog scale) within 15 minutes after tube removal. The most frequently reported sensation during chest tube removal was burning, followed by pain and pulling with mean intensities of 64, 62, and 45, respectively. Subjects reported having few sensations after the tube was removed with only five reporting soreness in the chest. The sensations and intensities did not differ for those who did and did not receive analgesia or for those having a pleural tube versus a mediastinal tube removed. The sensations were similar for the old and young subjects with younger subjects reporting higher intensities. Women reported pain more frequently than men, but the intensities of the sensations reported by men and women were not significantly different. The sensations reported during chest tube removal differ from those described in the literature and can be used to prepare patients more appropriately for chest tube removal.