Ketamine supresses REM sleep and markedly increases EEG gamma oscillations in the Wistar Kyoto rat model of treatment-resistant depression

Wistar-Kyoto (WKY) rats exhibit depression-like characteristics and decreased sensitivity to monoamine-based antidepressants, making them a suitable model of treatment-resistant depression (TRD). Ketamine has emerged recently as a rapidly acting antidepressant with high efficacy in TRD. Our aim was to determine whether subanaesthetic doses of ketamine can correct sleep and electroencephalogram (EEG) alterations in WKY rats and whether any ketamine-induced changes differentially affect WKY rats compared to Sprague-Dawley (SD) rats. Thus, we surgically implanted 8SD and 8 WKY adult male rats with telemetry transmitters and recorded their EEG, electromyogram, and locomotor activity after vehicle or ketamine (3, 5 or 10mg/kg, s.c.) treatment. We also monitored the plasma concentration of ketamine and its metabolites, norketamine and hydroxynorketamine in satellite animals. We found that WKY rats, have an increased amount of rapid eye movement (REM) sleep, fragmented sleep-wake pattern, and increased EEG delta power during non-REM sleep compared to SD rats. Ketamine suppressed REM sleep and increased EEG gamma power during wakefulness in both strains, but the gamma increase was almost twice as large in WKY rats than in SD rats. Ketamine also increased beta oscillations, but only in WKY rats. These differences in sleep and EEG are unlikely to be caused by dissimilarities in ketamine metabolism as the plasma concentrations of ketamine and its metabolites were similar in both strains. Our data suggest an enhanced antidepressant-like response to ketamine in WKY rats, and further support the predictive validity of acute REM sleep suppression as a measure of antidepressant responsiveness.

Utility of the digital rectal examination in the evaluation of undifferentiated abdominal pain

OBJECTIVE

The digital rectal examination (DRE) is commonly recommended in the evaluation of individuals with undifferentiated abdominal pain (UAP) despite negligible evidence. We aimed to determine its clinical utility.

METHODS

We prospectively enrolled 893 UAP subjects in an observational, convenience sample study at our urban, academic emergency department. Exclusion criteria were age younger than 18 years, vaginal or rectal bleeding, pregnancy, and primarily flank pain or vaginal complaint. Data forms were completed before laboratory testing, imaging, or other diagnostic maneuvers; and structured telephone and chart follow-up was performed. Physicians were asked to document DRE findings contemporaneously as well as their perception of the DRE's diagnostic impact. Final diagnosis in each case was compared with DRE result.

RESULTS

Five hundred thirty-eight of 893 (60%) subjects had a DRE performed at the discretion of the examining physician. The DRE was classified as "not useful" in 494 of 538 (92%). In the remaining 44 subjects, physicians reported having their differential diagnosis influenced by the DRE. Seventeen of 538 (3%; 0.95 confidence interval, 1.9%-5.0%) were diagnostically helped, and 12 of 538 (2%; 0.95 confidence interval, 1.3%-3.9%) were diagnostically harmed. Eleven of 538 (2%) were lost to final follow-up. Sensitivity analysis indicates that unless all 11 had diagnostically helpful DREs, the DRE was statistically as likely to be harmful as helpful.

CONCLUSION

Differential diagnosis was unaffected in most subjects undergoing DRE, and it appears as likely to be harmful as helpful in predicting final diagnosis. Given the discomfort and minimal predictive value of the DRE in this setting, highly selective use seems reasonable.

The Cyrano nose: a clinical review of hemangiomas of the nasal tip

It is always difficult to establish one preferred management program for all patients with any lesion, but serious consideration must be given to "no-touch" management of cavernous or capillary-cavernous hemangiomas of the nasal tip. This requires frequent consultations with the parents to furnish psychological support. If extreme pressure from the parents makes surgery inevitable, the operation should be limited to the immediate confines of the nasal tip.