Recent Publications by CFE Educators

The purpose of the research reported in this article was to test the effects of mental practice on clinical skill acquisition. The clinical skill to be acquired was the pelvic examination. Four instructional designs provided learning experiences for 160 second-year medical students at the University of Washington. The usual instructional sequence was the control, and three experimental sequences incorporated mental practice at premotor, postmotor, and combined premotor and postmotor stages of skill acquisition. Mental practice was facilitated by the use by students of audiotapes and headphones. Learner performance measures consisted of the evaluation of student ability to list the examination sequence, evaluations of an actual pelvic examination write-up, including both sequencing and findings, and observation ratings of skill performance. Mental practice produced better performance on the ability to list the examination sequence and the ability to record findings than no mental practice. Methods for providing mental practice created an orderly and efficient learning environment. Students found it helpful.

Despite the significant contribution of the periaqueductal gray (PAG) to an endogenous pain suppression system, little is known about its neurochemical organization. Previous pharmacological and physiological studies have indicated regional variations in the effectiveness with which the midbrain PAG can generate potent analgesia in response to either opiate microinjection or electrical stimulation. There is, however, no anatomical correlate of this regional variation. As a first step toward elucidating the neural circuitry underlying the PAG's contribution to endogenous pain suppression systems, we have mapped the distribution of leucine enkephalin (ENK)-like immunoreactivity in the cat PAG. Throughout the rostral-caudal extent of the PAG, ENK-containing neurons are clustered in discrete populations. ENK terminal field staining is somewhat more diffuse; however, there are several regions where terminal staining is consistently more intense. The distribution of ENK perikarya and terminals undergoes a ventral to dorsal shift from caudal to rostral PAG. Conceivably, the clustered distribution of ENK cells and terminals contributes to the differential effectiveness of various PAG regions in generating analgesia. The ventral-dorsal shift of ENK immunoreactivity may (1) correspond to a somatotopic organization within the PAG or (2) mirror the topographic relationship of the PAG's interactions with other components of the endogenous analgesia system. In addition, the changing pattern of ENK immunoreactivity may also reflect the involvement of the PAG and of endogenous opiates in systems other than those of pain control.

Cardiac tamponade is a rare complication of the postpericardiotomy syndrome in the absence of anticoagulation therapy. Three cases are presented where cardiac tamponade developed as a result of the postpericardiotomy syndrome with normal coagulation parameters. The pericardial effusions were serous in two and serosanguinous in the third case. Pericardial fluid studies were consistent with an exudate. The effusion resolved following a single pericardial tap and short-term corticosteroid therapy in one case. Repeated pericardiocentesis and drainage via an indwelling catheter were required in the other two cases.

Previous descriptions of immunoreactive vasoactive intestinal polypeptide (VIP) in small-diameter dorsal root ganglion cells in the superficial dorsal horn implicated this 28 amino acid peptide in nociceptive transmission. In this study, we examined the distribution of immunoreactive VIP in the spinal cord and caudal medulla of cats and rats. The PAP method was used on paraffin and frozen sections of 4% paraformaldehyde-fixed tissue, using antibodies to VIP that were raised in rabbits. The distribution of immunoreactive VIP, while similar to that of substance P (SP), a putative primary afferent peptide neurotransmitter, is more restricted. VIP staining is found in sacral dorsal roots and densely in the Lissauer tract. Dorsal horn staining is concentrated in lamina I. In contrast to SP, lamina II is almost devoid of staining. Labeled VIP axons course along the lateral curvature of the dorsal horn and arborize across lamina V and around the central canal. A collateral branch of these fibers distributes to the sacral autonomic nucleus. A few fibers could be traced from the root entry zone to the contralateral central gray. VIP axons also terminate between ependymal cells of the central canal. Unlike SP, immunoreactive VIP was restricted, almost exclusively, to the sacral cord. The few fibers in the lumbar enlargement and in the coccygeal cord apparently derive from ascending and descending sacral primary afferents. In fact, the VIP pattern is almost identical to that reported for afferents from the pelvic viscera, including a discontinuous rostrocaudal distribution. Since the staining pattern is also very similar to that of A-delta high-threshold mechanoreceptors, the possibility is discussed that whereas VIP is not a general "somatic" primary afferent transmitter, it may transmit nociceptive input from the pelvic viscera.

In order to study the organization of the rostral medulla of the cat and its contribution to pain control mechanisms, we have examined the afferent connections of the midline nucleus raphe magnus (NRM), the laterally located nucleus reticularis magnocellularis (Rmc), and the nucleus reticularis gigantocellularis (Rgc) located dorsal to Rmc. Iontophoretic injections of HRP were made into the three regions; the distribution of retrogradely labeled neurons in brainstem and spinal cord was then mapped. While significant differences characterize the source of afferents to Rgc and NRM/Rmc, there is little to distinguish that between NRM and Rmc. The predominant spinal projection is to Rgc; fewer labeled neurons were recorded after injections into Rmc. In contrast, no significant direct spinal projection to NRM was found. All three regions receive input from widespread areas within the medullary and pontine reticular formation. The most pronounced differences in the distribution of retrogradely labeled neurons were found in the midbrain. The major projection to both NRM and Rmc derives from the periaqueductal gray (PAG) and from the adjacent nucleus cuneiformis. Labeled cells are concentrated in the dorsal and lateral PAG; few are found in the ventrolateral PAG. In contrast, Rgc receives few afferents from the PAG; however, after Rgc injections, many cells were recorded in the deep layers of the contralateral tectum. None of the injection sites produced significant labeling of the catecholamine-rich dorsolateral pontine tegmentum or of the nucleus raphe dorsalis. The demonstration of significant PAG projections to NRM/Rmc provides anatomical evidence for the hypothesis that opiate and stimulation-produced analgesia involves connections from PAG to neurons of NRM and Rmc which, in turn, inhibit spinal nociceptors.