Letter to the Editor: Does fetal movement shape the maternal brain?

Here, we debate that fetal behavior may contribute to the dynamic changes observed in the maternal brain during the perinatal period. We call for future research to explore this perspective to understand the complex maternal-fetal relationship and how fetal signals influence the preparation for parenthood.

Differential effects of lithium isotopes in a ketamine-induced hyperactivity model of mania

Sub-anesthetic doses of ketamine produce an increase in rodent ambulation that is attenuated by co-administration of naturally-occurring lithium (LiN), the drug most commonly employed in the treatment of bipolar illness. As a consequence, ketamine-induced hyperactivity has been proposed as an animal model of manic behavior. The current study employed a modified version of this model to compare the potency of LiN to that of each of its two stable isotopes - lithium-6 (Li-6) and lithium-7 (Li-7). Since Li-7 constitutes 92.4% of the parent compound it was hypothesized to produce comparable behavioral effects to that of LiN. The current study was devised to determine whether Li-6 might be more, less, or equally effective at tempering hyperactivity relative to Li-7 or to LiN in an animal model of manic behavior. Male rats were maintained on a restricted but high-incentive diet containing a daily dose of 2.0 mEq/kg of lithium (LiN), Li-6 or Li-7 for 30 days. A control group consumed a diet infused with sodium chloride (NaCl) in place of lithium to control for the salty taste of the food. On day 30, baseline testing revealed no differences in the locomotor behavior among the four treatment groups. Animals then continued their Li/NaCl diets for an additional 11 days during which every subject received a single IP injection of either ketamine (25 mg/kg) or 0.9% physiological saline. On the final four days of this regimen, locomotor activity was assessed during 60 min sessions each beginning immediately after ketamine injection. While all three lithium groups produced comparable decreases in ketamine-induced hyperactivity on the first trial, by the fourth trial Li-6 animals exhibited significantly greater and more prolonged reductions in hyperactivity compared to either Li-7 and Li. These results suggest that Li-6 may be more effective at treating mania than its parent compound.

Activation of 5-HT1B receptors in the Lateral Habenula attenuates the anxiogenic effects of cocaine

Recent work has implicated the Lateral Habenula (LHb) in the production of anxiogenic and aversive states. It is innervated by all the major monoamine neurotransmitter systems and has projections that have been shown to modulate the activity of both dopaminergic and serotonergic brain regions. Cocaine is a stimulant drug of abuse that potentiates neurotransmission in these monoamine systems and recent research suggests that the drug's behavioral effects may be related in part to its actions within the LHb. The present research was therefore devised to test the hypothesis that alterations in serotonin (5-HT) function within the LHb can affect the behavioral response to cocaine. Male rats were fitted with intracranial guide cannula and trained to traverse a straight alleyway once a day for a 1 mg/kg i.v. injection of cocaine. Intra-LHb pretreatment with the 5-HT1B agonist CP 94,253 (0, 0.1, or 0.25 μg/side) attenuated the development of approach/avoidance "retreat" behaviors known to be a consequence of cocaine's dual rewarding (approach) and anxiogenic (avoidance) properties. This effect was reversed by co-administration of a selective 5-HT1B antagonist, NAS-181 (0.1 μg/side), demonstrating drug specificity at the 5-HT1B receptor. These data suggest that 5-HT1B signaling within the LHb contributes to the anxiogenic effects of cocaine.

Frequency and explanation of false negative diagnosis of aortic dissection by aortography and transesophageal echocardiography

OBJECTIVES

This study was designed to define the frequency and explanation of false negative diagnosis of aortic dissection by aortography and transesophageal echocardiography.

BACKGROUND

Aortography and transesophageal echocardiography have been widely utilized to diagnose aortic dissection. Previous reports have not fully addressed the reasons why these studies yield false negative results in a large number of patients with aortic dissection.

METHODS

Sixty-five consecutive patients with aortic dissection underwent aortography and transesophageal echocardiography. Diagnosis of aortic dissection was confirmed at operation or by computed tomography in all patients.

RESULTS

Biplane transesophageal echocardiograms yielded false negative results in two patients (sensitivity 97% [63 of 65]). Both patients had well localized DeBakey type II aortic dissection. The diagnosis was probably missed because of image interference from the air-filled trachea and mainstem bronchi. In both patients, the dissection was readily identified by aortography. Aortograms yielded false negative results in 15 patients (sensitivity 77% [50 of 65]); the aortic dissection was type I in 7 patients, type II in 1 and type III in 7. The dissection in all 15 patients was readily identified by transesophageal echocardiography. The missed diagnosis was probably due to a completely thrombosed false lumen or intramural hematoma with noncommunicating dissection in 13 patients and to a large ascending aortic aneurysm with nearly equal flow on both sides of the intimal flap in 2. In no patient was the diagnosis missed by both aortography and transesophageal echocardiography.

CONCLUSION

Transesophageal echocardiography is an excellent screening tool for aortic dissection. However, it may miss small type II aortic dissections localized to the upper portion of the ascending aorta because of image interference from the air-filled trachea. An intramural hematoma cannot be easily visualized by aortography, and this lesion is the principal reason for false negative aortographic findings.

Diagnosis of superior vena caval obstruction by transesophageal echocardiography

Superior vena caval (SVC) syndrome may be caused by extravascular compression or intravascular obstruction. Knowing the mechanism of SVC syndrome enables the physician to choose appropriate treatment. Transesophageal echocardiography (TEE) is a safe bedside procedure that is excellent for evaluating the SVC and its surrounding structures. We report the valuable role of TEE in demonstrating the mechanism of SVC syndrome.