Comparative study of laser versus radiofrequency myringotomy in rabbits: The effectiveness of mitomycin C application.

OBJECTIVE: To compare laser-assisted tympanostomy (LAT) with radiofrequency myringotomy (RFM), as well as the effectiveness of mitomycin C (MC) on the above techniques, in rabbits. STUDY DESIGN: Experimental animal research protocol. SETTING: University of Crete, School of Medicine, Medical Experimental Education and Research Center. METHODS: Bilateral myringotomies were performed under general anesthesia on 40 rabbits. LAT was performed on 20 animals (40 ears) and RFM on the remaining 20 animals (40 ears). MC (0.3 mg/mL) pledgets were applied to the right ears and saline pledgets to the left ears. Animals were monitored weekly using otomicroscopy until myringotomy closure. Kaplan-Meier survival techniques were used to compare myringotomy patency times. INTERVENTIONS: Under general anesthesia, bilateral LAT was performed on 20 rabbits and bilateral RFM on 20 rabbits. MAIN OUTCOME MEASURES: Myringotomy patency time. RESULTS: The mean patency times of the saline-treated ears were: 1.85 weeks (95% confidence interval [CI], 1.556-2.144 wk) for the LAT group and 1.70 weeks (95% CI, 1.494-1.906 wk) for the RFM group. This difference was not significant (p > 0.5). MC application significantly prolonged mean patency time (p < 0.0001) in both LAT and RFM groups. The mean patency times in the MC-treated ears were 5.45 weeks (95% CI, 5.226-5.674 wk) for the LAT group and 5.55 weeks (95% CI, 5.285-5.815 wk) for the RFM group. This difference was not significant (p > 0.5). CONCLUSION: There is no significant difference in myringotomy patency times between LAT and RFM techniques in rabbits, whereas MC significantly prolongs the patency rate of either technique.     

Resistance of the Obese Zucker Rat to insulin-induced Feeding and to Satiety Induced by Coinfusion of Insulin and Glucose

In normal rats, hypoglycemic doses of intravenous insulin bring about glucoprivic feeding but the same doses of insulin inhibit feeding when combined with doses of glucose that prevent hypoglycemia. In this study, these effects were compared between obese Zucker rats (fa-fa), known to present several abnormalities related to insulin, and normal Wistar rats by infusion of insulin (1 IU over 1 h), insulin plus glucose (5·1 g over 2 h) or vehicle. Feeding patterns and microstructure were automatically monitored. Contrary to its effect in the normal rats, insulin infusion did not enhance feeding in the Zucker rats but rather slightly decreased total food intake and meal duration. The insulin plus glucose infusion produced a total anorexia in normal rats but only a partial reduction in total food intake and metal duration was observed in Zucker rats. The impaired feeding effect of insulin in the Zucker rat may be related to its peripheral resistance to insulin which prevents a severe hypoglycemia and therefore glucoprivic feeding. The lack of inhibition of feeding when both insulin and glucose are infused may account for the well-known delayed satiation and large meals in the Zucker rat, possibly involving impaired hypothalamic action of insulin.     

Spontaneous feeding-related monoaminergic changes in the rostromedial hypothalamus revealed by microdialysis.

The activity of hypothalamic monoamines in response spontaneous feeding was investigated using the in vivo technique of brain microdialysis together with the instrumental recording of feeding pattern. The simultaneous variations of dopamine (DA), serotonin (5-HT), and their respective metabolites, DOPAC and 5-HIAA, were measured in the rostromedian hypothalamus, where the probe was located between the PVN and VMH. Throughout the experiment, the changes in DOPAC followed a mirror image of those in DA: DA regularly increased, reaching its zenith within the 15-min sample collected during the meal before returning to the same level as just before the meal. Following a premeal plateau, both 5-HT and 5-HIAA increased as soon as the beginning of feeding; 5-HT reached its zenith during the meal while 5-HIAA showed a more delayed and prolonged increase. When a new meal was initiated, 60 to 70 min later, a similar monoaminergic pattern was observed again. These data suggest that building up hunger is announced by an ascending slope of DA and setting up of satiation is concomitant with a descending slope of DA. Concerning serotonergic changes, the sharp 5-HT release during the meal would be a signal of satiation (transient preabsorptive fullness) while the longer-lasting increase in 5-HIAA, reflecting 5-HT synthesis, would be associated with satiety (more persistent postabsorptive state substituting satiation). These data partially confirm and extend previous pharmacological studies as well as the findings on deprivation-induced, imposed meals. They suggest a possible causal relation between monoaminergic changes and behavioral initiatives.     

No association between DUP25 and anxiety disorders.

Gratacos et al. [2001: Cell 106:367-379] described an interstitial duplication dup(15)q24q26 (DUP25) in patients with anxiety disorders; this duplication was found in approximately 90% of patients and in 7% of controls. In order to determine if DUP25 is present in additional individuals susceptible to panic attacks, we tested 44 patients with anxiety disorders, using probes 251c23 and 216c14 mapping in the 15q24 and 15q26 region. We have not detected any DUP25. Our results suggest that DUP25 is not common in people with anxiety disorders in the population tested here.     

Determination, using microdialysis, of hypothalamic serotonin variations in response to different macronutrients

In response to a chow meal in rats, we observed previously in PVN-VMH dialysates, an increase in serotonin (5-HT) that could be related to satiety or to metabolic consequences of the composition of the meal. Indeed, carbohydrates are admitted to increase 5-HT synthesis while proteins decrease it, but the time course and mechanisms of these effects were not known. For that purpose, pure carbohydrates, proteins, or fats were offered for 30 min and the changes in 5-HT from PVN-VMH dialysates were followed. Carbohydrates (85% starch + 15% sucrose) enhanced 5-HT levels as soon as the first 15 min of feeding, with a maximum 60 min later. Conversely, protein ingestion induced in the second 15 min of the meal, a decrease in 5-HT that lasted 2 h. During a fat meal (lard), 5-HT levels also decreased at the beginning of the meal and remained low during 45 min. The present data reassess the previous theories on the serotonergic effects of specific macronutrient ingestion. The effect of a fat meal on 5-HT levels had never been described so far. The increase in 5-HT in response to a carbohydrate meal is further specified. The 5-HT decrease induced by proteins, in agreement with the previous theories, is better explained now by using pure protein diets and extracellular 5-HT assay. However, all the changes observed start too early to be only metabolic in origin. Other mechanisms may occur, including the release of 5-HT in response to a meal to induce satiety.     

Acute injuries of the distal radioulnar joint

Distal radioulnar joint injuries can occur in isolation or in association with distal radius fractures, Galeazzi fractures, Essex-Lopresti injuries, and both-bone forearm fractures. The authors have classified DRUJ/TFCC injuries into stable, partially unstable (subluxation), and unstable (dislocation) patterns based on the injured structures and clinical findings. Clinical findings and plain radiographs are usually sufficient to diagnose the lesion, but axial CT scans are pathognomonic. Diagnostic arthroscopy is the next test of choice to visualize stable and partially unstable lesions. Stable injuries of the DRUJ/TFCC unresponsive to conservative measures require arthroscopic debridement of the TFCC tear, along with ulnar shortening if there is ulnar-positive variance. Partially unstable injuries, on the other hand, are treated with direct arthroscopic or open repair of the TFCC tear, once again, along with ulnar shortening if ulnar-positive variance is present. Unstable injuries include simple and complex DRUJ dislocations. A simple DRUJ dislocation is easily reducible but may be stable or unstable. In complex dislocation, reduction is not possible because there is soft tissue interposition or a significant tear. After the associated injury is dealt with, treatment for complex injuries requires exploration of the DRUJ, extraction of the interposed tissue, repair of the soft tissues, and open reduction and internal fixation of the ulnar styloid fracture (if present and displaced). The early recognition and appropriate treatment of an acute DRUJ injury are critical to avoid progression to a chronic DRUJ disorder, the treatment of which is much more difficult and much less satisfying.