Dual mechanisms of twitching during sleep in neonatal rats.

Twitches of the limbs during REM sleep in adult mammals result from descending motor activation from the brainstem. In contrast, many spontaneous movements in embryos appear similar to REM-related twitches and result from the local firing of spinal motor neurons. To determine which mechanism produces twitches in neonates, we analyzed twitching in 5- and 8-day-old rat pups that had spinal cords transected in the lower thoracic region. This transection separated motor units controlling forelimb movements from motor units controlling hindlimb movements. Spinal transection did not significantly affect the amount of forelimb twitching. In contrast, the amount of hindlimb twitching in transected pups was reduced by only 35%-50%. Given that hindlimb twitching was not eliminated by spinal transection, it is concluded that there are 2 independent mechanisms producing twitches at these ages.

A developmental and component analysis of active sleep.

A wide variety of hypotheses have been put forth that address the functional significance of active sleep. Despite the well-accepted fact that active sleep expresses itself predominantly in the perinatal period, the vast majority of these functional hypotheses are applicable largely, if not exclusively, to the adult. We build on the developmental approaches of previous researchers and propose that the individual components of active sleep (e.g., myoclonic twitches, rapid eye movements) exhibit unique developmental and phylogenetic histories and may serve independent functions in the developing organism. This dynamic perspective leads to specific experimental approaches aimed at the developmental roles of these components in the neonate, their maintenance roles in the adult, and the means by which these various components coalesce temporally in what is commonly referred to as a behavioral state.

Communication between the two pleural cavities after major cardiothoracic surgery: relevance to percutaneous intervention.

The authors describe evidence of communication between the two pleural cavities after major cardiothoracic surgery (combined heart and lung transplantation, heart transplantation, and correction of complex congenital heart disease) performed in three patients. In two patients, unilateral lung biopsy caused a symptomatic bilateral pneumothorax. This was successfully treated with insertion of a single chest tube in one patient and two chest tubes in the other patient. In the third patient, simultaneous evacuation of large bilateral pleural effusions was performed by means of unilateral thoracentesis because of the presence of a common pleural cavity.

Coaxial transthoracic fine-needle biopsy in patients with a history of malignant lymphoma.

Efficacy and safety of coaxial transthoracic fine-needle biopsy were evaluated in 54 patients with a history of malignant lymphoma and new chest lesions. Twenty-one patients had recurrent lymphoma. Correct diagnosis was made in 17 of the 21 patients (81%) after one biopsy. The sensitivity increased to 95% with repeat needle biopsy in three patients. Immunophenotyping (determining phenotype by means of immunologic examination) was essential for a definitive diagnosis of lymphoma in three patients. Non-lymphomatous malignancies were correctly diagnosed in 14 patients. An infectious organism was identified in 11 of 19 patients (58%) with benign lesions. Pneumothorax occurred in eight patients (15%), necessitating placement of a chest tube in two (4%). Mild hemoptysis was observed in four patients (7%). The authors conclude that coaxial transthoracic fine-needle biopsy in patients with a history of lymphoma is safe and accurate. The use of large cutting needles or surgical biopsy can be restricted to patients with false-negative findings at percutaneous biopsy and to patients in whom histologic transformation of lymphoma is suspected.