Assessing professionalism in early medical education: experience with peer evaluation and self-evaluation in the gross anatomy course

INTRODUCTION

As today's healthcare model moves toward more streamlined and corporate industrialism, it is our responsibility, as doctors, to ensure the integrity of medicine's foundation in professionalism. The erosion of professional values not only creates a climate of animosity, but reverberates negatively to impact the development of students, who model their behaviour after those they most respect. This hazard has spurred an evaluation of medical school curricula, with a new emphasis on professionalism in the philosophy of medical education. Courses such as Gross Anatomy that, in the past, offered "pure content," are now being used to teach and evaluate professionalism. The goal of this study was to determine if peer evaluation and self-evaluation used in conjunction and implemented early in the medical curriculum, can serve as useful tools to assess and provide feedback regarding professional behaviour in first-year medical students.

MATERIALS AND METHODS

From 1999 to 2003, students at Mayo Clinic College of Medicine evaluated themselves and their peers during the Gross and Developmental Anatomy Course. Numerical evaluations and written comments were statistically analysed within established categories of professionalism and correlated with academic performance, gender, and peer rating and self-rating.

RESULTS

The majority of written comments pertained to inter-professional respect, responsibility, and excellence. Students who gave higher peer evaluation and self-evaluation scores provided more positive comments, and students performing well in the course provided more positive comments about their peers and themselves than did those struggling academically. Students consistently rated their peers higher than themselves, and male students rated themselves higher than did female students.

CONCLUSIONS

Implementing peer evaluation and self-evaluation early in the medical curriculum is a valuable exercise in teaching first-year medical students assessment skills when evaluating their behaviour, as well as the behaviour of their colleagues.

Animated PowerPoint as a tool to teach anatomy

Anatomy is a visual science. For centuries, anatomic information has been conveyed through drawings that have been presented to students through every available medium. The projection of animated images from a computer is a medium that offers great promise in effecting improved communication of anatomic information. Using Microsoft PowerPoint software, we have developed animated presentations for all of our lectures in Gross and Developmental Anatomy. As a starting point, we scan pen-and-ink drawings to create a digital image. The image may be edited and manipulated in an image processing program. Next, the image is imported into a PowerPoint slide where it is labeled and otherwise enhanced (arteries overlaid with red color, veins in blue, etc.) and the enhancements are animated, as we describe here step by step. For the lecture, the file is loaded on a server that is accessible through a network from a computer in the lecture hall. The output is directed to a video projector and the PowerPoint presentation is projected in the "Slide Show" mode. We use a wireless mouse that allows us to control the presentation from anywhere in the room. Before the lecture, students are provided with the same unlabeled drawings as handouts, and during the lecture the students are actively engaged in labeling the drawings and making related notes. After the lecture, the file is saved in HTML format and posted on our course web site where students can access the slides. Evaluation by the students at the end of the course demonstrated that this style of presentation was very favorably received.

Biomechanics of total hip arthroplasty

The biomechanics of the hip joint provide an understanding of the development, evolution, and treatment of many disabling conditions of this joint. The available methods of biomechanical analysis include in vitro studies, in vivo studies, and theoretical mathematic analyses. The information obtained from these analyses have enabled the design of therapeutic programs to alleviate the symptoms of, and possibly delay the progression of, hip disease. The design of surgical procedures has been based on alterations of the biomechanics of the hip. These procedures have proven useful for treating pathologies such as osteoarthritis, hip dysplasia, and hip fractures. The study of biomechanics and biomaterials are integral to the current success of total hip arthroplasty in achieving pain relief and functional restoration.

Isolated paralysis of the extensor digitorum communis associated with the posterior (Thompson) approach to the proximal radius

Seven patients presented with an isolated extensor digitorum communis (EDC) palsy immediately after undergoing surgery in which the posterior (Thompson) approach to the proximal radius was used. All had normal neurologic examination findings documented prior to surgery. In an attempt to localize this lesion, the authors studied the arborization of the terminal motor branches of the posterior interosseous nerve (PIN) at the distal edge of the supinator. A common innervation pattern to the superficial extensor muscles was observed in 29 of 30 cadaveric limbs. In 10 of 10 specimens, when the EDC was subdivided into its individual bellies, a reproducible pattern emerged: the proximal EDC muscles of the middle and ring fingers were supplied primarily by the recurrent nerve branch(es) and the EDC muscles of the index and little fingers, by separate nerve branches. Consistent with our anatomic findings, perioperative stimulation of the recurrent branch in 1 neurologically intact patient resulted in middle and ring finger extension. Electromyography in 8 normal limbs showed that the middle and ring fingers could be activated together without the index and little fingers in all cases. We believe that these patients with isolated EDC nerve palsy may have sustained an iatrogenic injury to EDC motor branches, distal to the supinator rather than to a PIN fascicle near the proximal supinator.

The adrenal medulla as a wet sponge: a role for the intramedullary venous vasculature?

Synchronous contractions in the intramedullary venous vasculature have been postulated to assist in the discharge of hormones from the stimulated adrenal medulla in a manner analogous to the squeezing of a wet sponge. This study reports on two experimental approaches to support the hypothesis that contractions in the venous vasculature may contribute to the hormonal efflux. Firstly, the bovine adrenal medulla was perfused retrogradely via the bovine central adrenomedullary vein end changes in the vascular volume were assessed as changes in wet weight of the perfused tissue. Stimulation with acetylcholine and carbachol resulted in repetitive, transient weight losses, suggesting cholinergically mediated reductions in the vascular volume. Secondly, the contractile properties of the longitudinal layers of smooth muscle cells in the intramedullary venous system were characterized, using the bovine central adrenomedullary vein as a model. The results showed that the longitudinal layers of this vein were, similarly to the circular layers, selectively contracted by endothelin-1 via an ETA-like receptor, by neuropeptide Y and by membrane depolarization (high K+). However, the vein was insensitive to electrical stimulation acetylcholine and carbacho, as well as to catecholamines. These results suggest neuropeptide Y, released from the cholinergically stimulated chromaffin cells, as the most likely mediator of stimulus-evoked synchronous contractions of the venous vasculature in the bovine adrenal medulla. Together, these experiments provide support for the 'wet sponge' hypothesis for hormonal discharge from the adrenal gland.

An anatomic comparison of septocutaneous free flaps from the thigh region

Various free flaps have been utilized in the thigh region, however there are few systematic clinicoanatomic studies of the thigh region. The purpose of this study is to clarify the clinicoanatomic characteristics of the free septocutaneous thigh flap. Forty-two dissections were carried out in unenbalmed cadavers. The pedicle was observed in all specimens in the anterolateral thigh (ALT), medial thigh, gluteal thigh, and lateral thigh flaps. The pedicle was observed in 46% of the specimens in the anteromedial thigh flap. The pedicle was observed in 86% of the specimens in the posterior thigh flap. The pedicle length (153 +/- 23 mm) of the ALT flap was the longest pedicle in the thigh flaps. The internal diameter of the pedicle of the ALT flap (3.0 +/- 1.0 mm), which could be used for anastomosis, is the largest in the septocutaneous thigh flaps. The clinicoanatomic characteristics of thigh flaps are clarified.

Surgical anatomy for endoscopic subfascial division of perforating veins

PURPOSE

This study was undertaken to define the surgical anatomy of the medial perforating veins (PVs) of the leg and to provide information on how to gain access to all medial PVs from the superficial posterior compartment during a subfascial endoscopic procedure.

METHODS

The venous anatomy of 40 limbs (from 23 cadavers) were studied. Medial PVs located between the ankle and the tibial tuberosity were dissected. None of the subjects had pathologic evidence of venous disease. Each PV's type (direct or indirect), size (< 1 mm, 1 to 2 mm, > 2 mm), location (distances from ankle [D1], and tibia [D2]), and accessibility from the superficial posterior compartment were recorded.

RESULTS

Five hundred fifty-two PVs were identified (mean, 13.8; range, 7 to 22). Two hundred eighty-seven PVs (52%) directly connected the superficial with the deep systems, 228 (41%) were indirect muscle perforators, and 37 PVs (7%) were undetermined. One hundred thirty-seven PVs (25%) were > 2 mm. Sixty-three percent of PVs were accessible from the superficial posterior compartment. In the distal half of the leg, two groups of direct PVs could be identified (Cockett II: D1, 7 to 9 cm; Cockett III: D1, 10 to 12 cm). In the proximal half of the leg, paratibial direct PVs (D2 < or = 1 cm) were found clustered in three groups (D1, 18 to 22 cm; D1, 23 to 27 cm; D1, 28 to 32 cm).

CONCLUSIONS

Our study confirmed the presence of the Cockett II and III PVs and three groups of proximal paratibial PVs, including the "24-cm" perforators. Two thirds of the medial direct PVs are accessible for endoscopic division from the superficial posterior compartment. To divide paratibial PVs, however, incision of the paratibial deep fascia is frequently required.

Guyon's canal revisited: an anatomic study of the carpal ulnar neurovascular space

The boundaries of the space through which the ulnar neurovascular bundle crosses the wrist have been reinvestigated. Using gross dissections, transverse and sagittal sections, and histologic study, we determined that the roof of Guyon's canal, the "carpal ulnar neurovascular space," does not directly connect to the hamate bone, as is currently accepted. The roof of this space extends radially to the hook of hamate and attaches to the flexor retinaculum. This anatomic arrangement allows the ulnar artery and sensory component of the ulnar nerve to course radially to the hook of hamate, where they lie on the flexor retinaculum (transverse carpal ligament). The roof and radial border have three segments: (1) a proximal segment that begins near the pisiform and extends distally to the level of the hook of hamate but does not attach directly to it, (2) a central segment that contains only adipose tissue, and (3) a distal fascial layer that includes the palmaris brevis muscle. The floor of the space consists of the muscles of the hypothenar eminence, their fibers of origin, and the flexor retinaculum (transverse carpal ligament). Guyon accurately described the proximal portion of the carpal ulnar neurovascular space, but his description has been misinterpreted; the hook of hamate does not serve as the radial boundary of Guyon's canal. The anatomic relationships of the "carpal ulnar neurovascular space" need to be appreciated to avoid complications during carpal tunnel surgery.

Ulnar nerve anatomy and compression

Compression of the ulnar nerve can be understood in terms of the anatomic and dynamic factors. Although the ulnar nerve may be compressed at any point along its course, it is particularly susceptible at the elbow and the wrist. Clinically relevant anatomy will be reviewed in an attempt to provide the reader with a logical framework for successfully diagnosing and managing typical and atypical ulnar nerve compression lesions.

Morphology of the torn rotator cuff

The morphological characteristics of shoulders with torn rotator cuffs were determined using 41 embalmed specimens. The following parameters were measured in the supraspinatus (SSP), infraspinatus (ISP) and subscapularis (SSC) muscles: the length, thickness and width of the extramuscular tendon; the length of the intramuscular tendon; the length and width of a tear, if present, muscle fibre length; and muscle volume. The cross-sectional area (CSA) of the tendon was measured on the photographic image of slices of the tendon using an image analysis system, and the CSA of the muscle was calculated by dividing the muscle volume by muscle fibre length. The rotator cuff was intact in 11 shoulders. A partial-thickness tear of the cuff was present in 12 shoulders, a full-thickness tear of the SSP in 11 shoulders, and a full-thickness tear of more than 2 tendons in 7. Overall incidence of full-thickness tears of the rotator cuff was 44%, and that of partial-thickness tears 29%. With increase of tear size, the functional tendon length (extramuscular tendon length plus tear length) increased by a statistically significant amount in the SSP, ISP and SSC, whereas muscle fibre length decreased in SSP and ISP. It is concluded that the increased functional tendon length and decreased muscle fibre length are the main morphological changes that make the rotator cuff a physiologically abnormal unit. Surgical repair of the torn cuff would be expected to improve these anatomical changes and restore the kinetics of the glenohumeral joint.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal medulla and Parkinson's disease

Parkinson's disease has been described as a multisystem disorder that includes alterations in the function of the autonomic nervous system. The activity of the adrenal medulla in this disease has not been thoroughly investigated. Previous reports are reviewed that demonstrate that the adrenal medullae of parkinsonian patients are compromised, having a decreased content of all catecholamines and several neuropeptides. An animal model was used to investigate whether the observations made in human patients were related to extended treatment with antiparkinsonian medications or were a natural concomitant of the disease. Administration of L-dopa and/or carbidopa to C57BL mice for 4-16 weeks had no significant effect on the level of any of the adrenal medullary catecholamines. Treatment with MPTP 4-16 weeks prior to sacrifice did not deplete adrenal medullary catecholamines in these animals, thus not fully mimicking Parkinson's disease in this animal model. The only significant effect was an interaction between group (MPTP or control) and treatment with antiparkinsonian medications; L-dopa, in the absence and presence of carbidopa, had opposite effects in the two groups. Based primarily on the lack of effect of antiparkinsonian medications on adrenal medullary catecholamines, it was concluded that the adrenal medullary depletion observed in human patients was a peripheral concomitant of Parkinson's disease.

Flexor carpi radialis tendinitis. Part I: Operative anatomy

The anatomical characteristics of the flexor carpi radialis tendon, the tendon sheath, the tunnel boundaries, and the adjacent structures were examined in twenty-five adult cadaveric specimens. Transverse and sagittal sections of the wrist and forearm, tenograms, and histological sections of the tendon were made from two additional specimens each. The musculotendinous portion of the flexor carpi radialis tendon begins an average of fifteen centimeters (range, twelve to seventeen centimeters) proximal to the radiocarpal joint; the muscular fibers end an average of eight centimeters (range, six to nine centimeters) proximal to the wrist. The synovial sheath extends from the origin to the insertion. The tendon enters a fibro-osseous tunnel at the proximal border of the trapezium and is separated from the carpal canal by a thick septum that functions, at its distal border, as a pivot point for the flexor pollicis longus. Within the tunnel, the tendon occupies 90 per cent of the available space and is in direct contact with the slightly roughened surface of the trapezium. The tendon lies within a few millimeters of the distal aspect of the radius, the scaphoid tubercle, the scaphoid-trapezium-trapezoid joint, and the carpometacarpal joint of the thumb. In most patients, the flexor carpi radialis tendon is inserted at three locations. A small slip is connected to the trapezial crest or tuberosity; 80 per cent of the remaining tendon is inserted on the base of the second metacarpal and 20 per cent, on the base of the third metacarpal. The deep palmar arch is located two to three millimeters distal to the insertion of the tendon.

The ulnar neurovascular bundle at the wrist. A technical note on endoscopic carpal tunnel release

The boundaries of Guyon's canal have recently been redefined by a series of anatomical dissections. These showed that the confines of this space do not extend from the pisiform to the hook of the hamate, as currently accepted. The fascial roof extends radial to the hook of the hamate, which allows the ulnar neurovascular bundle to course radial to the hamate hook. The position of the ulnar nerve and artery is of particular significance for endoscopic carpal tunnel release. Most endoscopic devices are designed to divide the flexor retinaculum just to the radial aspect of the hamate hook. Utilizing cross-sectional analysis of nine cadaver specimens, we found the ulnar artery to course radial to the hamate hook in five and palmar to it in four. Therefore, the ulnar artery may be at greater risk of injury during endoscopic procedures than previously recognized.

Variations of the arterial anatomy of the foot

Reconstruction of the arteries of the foot in patients with severe chronic arterial occlusive disease has become a routine and valuable procedure. However, it is frequently difficult to select the optimal site for the distal arterial anastomosis. In order to determine the most important anatomic variations of foot arteries and the relationship of the dorsalis pedis artery to crossing tendons, the following study was performed in 30 cadaver limbs of 17 persons (9 men and 8 women). Their mean age at death was 69.8 years (range: 42 to 93 years). Methods to evaluate anatomy included anatomic dissection, arteriography, and preparation of corrosion cast models. The latter was performed by injection of liquid plastic and catalyst into the tibial arteries followed by chemical débridement of the soft tissue of the foot. Photographs of the corrosion cast models were taken at various stages of soft tissue dissolution. The dorsalis pedis artery was absent in 6.7% of the cases, and the arcuate artery was absent in 33%. The dorsalis pedis artery arose from the peroneal artery in 6.7%. The dorsalis pedis artery crossed under the extensor hallucis longus tendon at the ankle in 54%, above the ankle in 43%, but below the ankle in only 3%. Our study suggests that the optimal site for the dorsalis pedis artery anastomosis on the foot is the segment distal to the ankle.

MR imaging of knee hyaline cartilage: evaluation of two- and three-dimensional sequences

Magnetic resonance (MR) imaging of cadaveric knees was performed to determine optimal sequences for visualization of hyaline cartilage. Full-thickness cartilage lesions ranging in diameter from 1 to 5 mm and a partial-thickness cartilage lesion 15 mm in diameter were created in the femoral articular surfaces of three cadaveric knees. The knees were then imaged with a 1.5-T imager with various two-dimensional and high-resolution three-dimensional (3D) techniques. After imaging, the knee specimens were sectioned for evaluation. Measurements of cartilage thickness in fast spin-echo images correlated best with those in the gross specimen. Diffuse areas of cartilage thinning were also most accurately identified with fast spin-echo images. Small, focal cartilage defects were best delineated in 3D SPGR (spoiled GRASS [gradient-recalled acquisition in the steady state]) images.

Inorganic thiophosphate effects on chromaffin cell structure and function

The effect was determined of replacing medium inorganic phosphate with thiophosphate on the structure and function of cultured bovine chromaffin cells. Cell cultures were incubated in normal medium containing fetal bovine serum, phosphate free medium or similar medium supplemented with inorganic phosphate or thiophosphate. In contrast to the other media, cells cultured with thiophosphate medium for 3-4 days showed seriously compromised structure and functions. The cells lost 75% of their catecholamine content and their ability to secrete remaining catecholamines in response to nicotine stimulation. Radiolabelled thiophosphate was rapidly taken up by the cells and, in long-term experiments, was incorporated largely into a 97-121 kDa protein band on SDS-PAGE. Additional minor bands were found to a lesser, variable extent. Transmission electron micrographs of cells treated with thiophosphate showed extensive depletion of chromaffin vesicles and disruption of mitochondria, suggesting that the functional damage noted with these cells could be associated with damage to mitochondria. Analysis of general cell metabolic activity by conversion of the dye (3-[3,4-dimethylthiazol-2-yl]-3,5-diphenyltetrazolium bromide) to its formazan derivative indicated increased metabolic activity at early stages of exposure to thiophosphate followed by a decline with continued exposure, supporting the argument for an overall depression of cell metabolism. Uptake of the dye neutral red, which is avidly accumulated by chromaffin cells, was also reduced for cells exposed to thiophosphate. The data suggest that thiophosphate enters chromaffin cells and disrupts energy dependent cell functions, including catecholamine storage and secretion.

Decreased levels of [Met]enkephalin, neuropeptide Y, substance P, and vasoactive intestinal peptide in parkinsonian adrenal medulla

Adrenal medullary tissue was collected from parkinsonian patients at autopsy and at the time of autologous transplantation of the adrenal medulla to the caudate nucleus, and from nonparkinsonian patients at autopsy and during nephrectomy. Levels of the following neuropeptides were measured by radioimmunoassay in samples of the medullary tissue: neuropeptide Y (NPY), substance P (SP), [Met]enkephalin ([Met]ENK), vasoactive intestinal peptide (VIP), peptide YY, and bombesin-like immunoreactivity. Regression analysis was used to establish a relationship between patient age, time to organ harvest, and peptide levels in nonparkinsonian tissue. Levels of [Met]ENK, VIP, NPY, and SP were significantly lower in parkinsonian adrenal medullae than that predicted from the control group. These results suggest that the adrenal medulla of a parkinsonian patient is severely compromised, either by the disease process itself or by the antiparkinsonian medications used to treat the symptoms of the disease.

Microscopic anatomy of the baboon (Papio hamadryas) adrenal medulla

Adrenal medullas of 2 baboons perfused with formaldehyde/glutaraldehyde and tannic acid were studied by light and electron microscopy. Tissues were postfixed in OsO4. This procedure allows identification of noradrenaline cells on the basis of a selective reaction of glutaraldehyde with noradrenaline vesicles. As positive control for noradrenaline cells, similarly treated mouse adrenal medullas were also examined. Light microscopic examination of thick sections of baboon medullas did not show noradrenaline cells. In contrast, mouse adrenal medullas showed noradrenaline cells scattered in small groups among the much lighter adrenaline cells. By electron microscopy no noradrenaline cells were seen in the baboon medulla while mouse adrenal medullas showed noradrenaline cells with vesicles possessing exceedingly dense cores and light spaces within their limiting membranes. Otherwise, the majority of the baboon chromaffin cells showed chromaffin vesicles which were round or elongated, 150-520 nm in diameter, and heterogenous in electron density. Cytoplasmic densities were occasionally seen attached to the inner aspect of the plasmalemma, particularly along areas close to blood capillaries. These densities could be chromaffin vesicles in the process of exocytosis. This is the first report of exocytotic profiles in a primate medulla. Occasional small vesicle-containing cells also were present. The vast majority of their vesicles were electron dense. Several possible alternatives for the varied catecholamine vesicular osmiophilia, were discussed. It was suggested that this could be attributed to varied concentration of noradrenaline and adrenaline neurohormones among the vesicle population.

Reduced D2 dopamine and muscarinic cholinergic receptor densities in caudate specimens from fluctuating parkinsonian patients

Binding of spiperone and 3-quinuclidinyl benzilate (QNB), both labeled with hydrogen 3 (3H), were measured in caudate tissue obtained from 8 living parkinsonian patients at the time of cerebral transplantation. This was clinically homogeneous group of patients. All remained predominantly responsive to levodopa, although with marked disability secondary to clinical fluctuations (short-duration responses) and medication-induced dyskinesias; all were receiving substantial doses of levodopa and 6 of the 8 patients were additionally receiving bromocriptine or pergolide. Binding densities of dopamine D2 receptors, as measured by [3H]spiperone binding, were reduced in this group of patients, compared to caudate specimens from autopsy control subjects. This findings may reflect medication-induced receptor downregulation. Parallel changes occurred with muscarinic cholinergic receptors; [3H]QNB binding was significantly reduced, compared to autopsy control values. This reduction of muscarinic receptors might be due to loss of nigrostriatal terminals that are known to contain muscarinic receptors. Alternatively, muscarinic receptors may have been downregulated by increased corticostriatal glutamatergic input to cholinergic cells, inferred to be present based on the prominent levodopa-induced dyskinesias. Finally, receptor deficits could have been a reflection of more widespread degenerative cerebral disease, although levodopa-refractory symptoms were generally not pronounced in these patients.

Infraclavicular ulnar nerve entrapment due to a chondroepitrochlearis muscle

The chondroepitrochlearis muscle is an extremely rare muscle, arising from the pectoralis major, crossing over the neurovascular bundle in the axilla and inserting into the brachial fascia and medial epicondyle of the humerus. This paper presents the first known neurological complication due to the chondroepitrochlearis muscle.

Ischemic injury to the spinal cord or lumbosacral plexus after aorto-iliac reconstruction

Between January 1, 1980, and June 30, 1989, 9 patients (6 males and 3 females) developed ischemic injury to the spinal cord or lumbosacral plexus following 3,320 operations on the abdominal aorta (0.3%). The incidence of this complication was 0.1% (2 of 1,901) after elective and 1.4% (3 of 210) after emergency abdominal aortic aneurysm repair, and 0.3% (4 of 1,209) after repair for occlusive disease. Three of the latter had prior clinical evidence of distal embolization. Eight grafts were bifurcated (aorto-iliac:four, aorto-femoral: three, aorto-ilio-femoral:one). One patient underwent extra-anatomic revascularization. Only two patients had supraceliac aortic cross-clamping and one patient underwent exclusion of both internal iliac arteries. Four patients had hypotension. Early mortality was 22% (two of nine). Severe perioperative complications, mostly due to associated visceral and somatic ischemia and sepsis, were present in seven of the nine patients. The extent and type of the neurologic injury correlated with long-term outcome. Patients with ischemic injury of the lumbosacral roots or plexus had better recovery. Attention to the pelvic circulation and the collateral blood supply is important. Use of gentle technique to prevent embolization, avoidance of hypotension and prolonged supraceliac cross-clamping, revascularization of at least one internal iliac artery, and the use of heparin may decrease but not eliminate paraplegia. Once this unexpected complication occurs, careful neurologic evaluation should be done to localize the lesion and aid prognosis.

The cubital tunnel and ulnar neuropathy

The anatomy of the cubital tunnel and its relationship to ulnar nerve compression is not well documented. In 27 cadaver elbows the proximal edge of the roof of the cubital tunnel was formed by a fibrous band that we call the cubital tunnel retinaculum (CTR). The band is about 4 mm wide, extending from the medial epicondyle to the olecranon, and perpendicular to the flexor carpi ulnaris aponeurosis. Variations in the CTR were classified into four types. In type 0 (n = 1) the CTR was absent. In type Ia (n = 17), the retinaculum was lax in extension and taut in full flexion. In type Ib (n = 6) it was tight in positions short of full flexion (90 degrees to 120 degrees). In type II (n = 3) it was replaced by a muscle, the anconeus epitrochlearis. The CTR appears to be a remnant of the anconeus epitrochlearis muscle and its function is to hold the ulnar nerve in position. Variations in the anatomy of the CTR may explain certain types of ulnar neuropathy. Its absence (type 0 CTR) permits ulnar nerve displacement. Type Ia is normal and does not cause ulnar neuropathy. Type Ib can cause dynamic nerve compression with elbow flexion. Type II may be associated with static compression due to the bulk of the anconeus epitrochlearis muscle.

Partial median nerve entrapment in the distal arm because of an accessory bicipital aponeurosis

We present a newly described entrapment of the median nerve caused by compression in the distal arm because of an accessory bicipital aponeurosis. It is characterized by the paresis or paralysis of muscles innervated by the anterior interosseous branch of the median nerve--the flexor pollicis longus, the flexor digitorum profundus, and the pronator quadratus--as well as other more proximal median nerve innervated muscles, namely, the pronator teres and flexor carpi radialis. Sensibility is intact. The site of the Tinel's sign in the distal arm and the clinical appearance of an accessory bicipital aponeurosis help to localize the lesion. Electrodiagnostic studies are also important in establishing the site of the entrapment. The clinical and surgical findings are correlated with the internal topography of the median nerve at its site of compression. It is important to differentiate this syndrome from the classic anterior interosseous syndrome and other nerve entrapments at the elbow and arm. Surgical exploration is indicated if there is no clinical or electromyographic improvement in three to four months after the onset of symptoms.

Mechanisms of toxicity and cellular resistance to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and 1-methyl-4-phenylpyridinium in adrenomedullary chromaffin cell cultures

Bovine adrenomedullary chromaffin (BAMC) cells, cultured in a defined medium, were used to study the mechanisms of toxicity and cellular resistance to the catecholamine neuron toxicants 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and 1-methyl-4-phenylpyridinium (MPP+). The viability of the cells was assessed biochemically [cellular catecholamine content and the catalytic activities of tyrosine hydroxylase (TH) and lactate dehydrogenase (LDH)] and anatomically (by electron microscopy). When cultures of BAMC cells were exposed to MPTP or MPP+ for 3 days, a marked loss of cellular catecholamines and TH activity was observed. The addition of an inhibitor of monoamine oxidase (MAO) B (Ro 19-6327), but not MAO A (clorgyline), prevented the toxicity of MPTP but not that of MPP+. In addition, the cellular toxicity of MPP+, but not MPTP, was antagonized by desmethylimipramine, an inhibitor of cellular catecholamine uptake. The toxicity of MPP+ was time dependent, with losses of TH and the release of cellular LDH occurring after 48 h in culture. Catecholamine depletion occurred somewhat sooner, being evident after 24 h of exposure to MPP+. The cellular toxicity of MPP+ was concentration dependent and significantly enhanced by inhibitors of catecholamine vesicular uptake (reserpine, tetrabenazine, or Ro 4-1284). Electron microscopic examination of cells treated with either MPP+, tetrabenazine, or their combination revealed that MPP+ damaged BAMC cells and that this damage was markedly potentiated by the inhibition of vesicular uptake by tetrabenazine. The concentration of glucose in the culture media of untreated cells slowly decreased as a function of time. The rate of glucose consumption was markedly accelerated by MPP+ treatment and the losses in cell TH and the release of LDH into the media were preceded by a 99% depletion of glucose from the media. In cultures not treated with MPP+, lactate accumulated in the media as a function of time. Addition of MPP+ to the media increased the formation of lactate, in a concentration-dependent manner. Reserpine pretreatment further enhanced the production of lactate in response to MPP+. Culturing cells in glucose-free medium greatly potentiated the effects of MPP+ on cellular TH and catecholamines. The toxicity observed after 3 days' exposure of BAMC cells to MPP+ could be prevented when the medium was replaced with fresh medium every 24 h. The effects of glucose deprivation and reserpine were observed to be additive. The ability of MPP+ to affect mitochondrial function is determined by the capacity of the storage vesicle to sequester the pyridinium, acting as a cytosolic "buffer."(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenal medullary transplantation into the brain for treatment of Parkinson's disease: clinical outcome and neurochemical studies

Transplantation of adrenal medulla into the caudate nucleus as treatment for Parkinson's disease was performed in eight patients. Although our previous 6-month follow-up revealed early modest improvement, an extension of that follow-up to 1 year disclosed no additional gains in any patient. At the end of 1 year, only one patient could be categorized as moderately improved; three patients were mildly improved, and four patients were unimproved. The rationale for transplanting adrenal medulla was to reestablish a physiologic source of dopamine to the striatum. We measured cerebrospinal fluid (CSF) and plasma catecholamines and metabolites before and after transplantation. Conjugated dopamine (the predominant form of dopamine found in the CSF) and homovanillic acid (the major dopamine metabolite) were modestly and inconsistently increased in the CSF. Conjugated and free epinephrine and norepinephrine, as well as 3-methoxy-4-hydroxyphenylglycol concentrations were not increased in CSF after graft placement, an indication that the adrenal chromaffin cells were no longer producing high levels of these nondopamine catecholamines and metabolites. CSF cortisol concentrations were not increased after transplantation, compared with values from controls, consistent with low numbers of functioning adrenal cortical cells contaminating the graft (or poor survival). Posttransplantation CSF did not induce a neurotrophic effect in cell cultures of 15-day embryonic rat dorsal root ganglion or PC12 (rat pheochromocytoma) cell lines. Survival of samples of patients' adrenal medullary tissue for 2 weeks in tissue culture attested to the viability of the graft at the time of transplantation. The relative concentrations of dopamine to epinephrine or norepinephrine increased in these cultured adrenal medullary cells, presumably because of loss of the glucocorticoid influence on catecholamine synthesis. A wide variety of factors could have contributed to our failure to replicate the earlier impressive results of adrenal-to-brain transplantation reported by others. Continued transplantation studies in animal models of parkinsonism are necessary for better elucidation of these factors.

Measurement of lumbar CSF levels of met-enkephalin, encrypted met-enkephalin, and neuropeptide Y in normal patients and in patients with Parkinson's disease before and after autologous transplantation of adrenal medulla into the caudate nucleus

The levels in lumbar cerebrospinal fluid (CSF) of neuropeptide Y (NPY), methionine enkephalin (Enk), and Enk contained in amino- and carboxy-terminus extended forms (X-Enk) were examined in nine control patients undergoing elective surgical procedures and in eight patients with advanced Parkinson's disease, before and after the autologous transplantation of adrenal medullary fragments into the right caudate nucleus. The levels of CSF Enk and X-Enk before surgery in patients with Parkinson's disease were significantly less than those observed in control patients (Enk, 166 +/- 38 vs 264 +/- 44 pg/ml; X-Enk, 794 +/- 416 vs 1497 +/- 153 pg/ml). NPY levels did not differ (221 +/- 25 vs 193 +/- 23 pg/ml). After surgery, lumbar CSF samples were taken at 6 weeks, 12 weeks, 6 months, and 9 months. Placement of adrenal medullary fragments into the striatum had no effect on the levels of NPY or Enk at any time point. The levels of X-Enk were significantly enhanced only at 12 weeks (1138 +/- 140 pg/ml) but were at presurgical levels again by 6 months. These data suggest that the transplant was not functionally contributing to the CSF levels of these peptides.

The secretion of catecholamines, chromogranin A and neuropeptide Y from the adrenal medulla of the cat via the adrenolumbar vein and thoracic duct: different anatomic routes based on size

Secretion of the adrenal medulla was stimulated in nine cats by insulin-induced hypoglycemia. Levels of catecholamines (mol. wt 153-183), neuropeptide Y (mol. wt 4254) and chromogranin A (mol. wt 48,000) were measured in concurrently collected samples of adrenolumbar venous blood and thoracic duct lymph for up to 4 h following insulin administration. Insulin-induced hypoglycemia elicited an increase in the secretion of catecholamines, which reached peak levels in the adrenolumbar venous plasma at 1.5-2 h and in the lymph at 2.5 h. Although catecholamines were the most numerous measured molecules in the lymph, levels of norepinephrine and epinephrine were 75-250-fold less than those found in the adrenolumbar venous plasma. Neuropeptide Y in the adrenolumbar venous plasma reached peak levels between 1 and 1.5 h; at this time approximately 20% of the peak venous amount was detected in the lymph. Chromogranin A was found in approximately equal amounts in both plasma and lymph; the peak level in the plasma occurred at 1.5-2 h, while that in the lymph was reached at 2-3 h. We suggest that the size of a molecule influences the route it takes following exocytosis from the chromaffin vesicle. Smaller molecules such as catecholamines may pass directly into the circulation, while larger molecules such as chromogranin A may be temporarily sequestered in the interstitial space before passing into the lymph, and hence into the circulation.

Indomethacin attenuates the constriction of canine epicardial coronary arteries to acetylcholine in the absence of endothelium: contribution of platelets to vasoconstriction in vivo

This study was designed to evaluate the in vivo effect of acetylcholine on endothelial-damaged canine epicardial coronary arteries and the potential contribution of platelets to those acetylcholine-induced responses. Changes in left anterior descending artery cross-sectional area were determined by quantitative angiography in the closed chest anesthetized dog. Baseline cross-sectional area of the left anterior descending artery was not changed by removal of the endothelium by balloon-tipped catheter. Increased constrictor tone produced by prostaglandin F2 alpha was comparable in endothelium-intact and endothelium-removed vessels, supporting an endothelium-independent mechanism for prostaglandin F2 alpha in vivo. Acetylcholine produced anterior descending artery vasodilation with the endothelium intact; a comparable maximal dilator response was also obtained in the presence of increased constrictor tone (prostaglandin F2 alpha). In contrast, acetylcholine produced vasoconstriction of the anterior descending artery when the endothelium was removed. To evaluate the mechanism of acetylcholine-induced vasoconstriction in endothelium-removed vessels, the same protocol was completed in the presence of the platelet inhibitor indomethacin. Indomethacin did not alter baseline cross-sectional area or the dilator response to acetylcholine in endothelium-intact vessels. In contrast, the constrictor response in endothelium-removed vessels was antagonized, and a dilator response comparable with that in endothelium-intact vessels was produced by acetylcholine. The results of this study provide an experimental basis for the observations in human studies in which apparently atherosclerotic vessels constrict in response to acetylcholine. Removal of the endothelium in vivo abolishes the dilator response to acetylcholine and converts the acetylcholine response to vasoconstriction or vasospasm.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural demonstration of exocytosis in the intact rat adrenal medulla

Evidence is presented for morphological proof of exocytosis in the rat adrenal medulla in situ. Techniques were modified to allow perfusion of the intact adrenal gland with secretagogues (or electrical stimulation) followed by tannic acid. Unstimulated specimens demonstrated exocytotic (omega-shaped) profiles filled with flocculent material. This flocculation was also seen in the intercellular space. Stimulation of the adrenal medulla also resulted in the appearance of exocytotic profiles and an accumulation of the flocculent mass. This was often most evident in the subendothelial space. This is the first demonstration of exocytosis in the rat adrenal medulla by electron microscopy. The techniques used in this study will be useful for studying the pathway of secretory products of the adrenal chromaffin cell before they enter the vascular system.

Cerebrospinal fluid indices of blood-brain barrier permeability following adrenal-brain transplantation in patients with Parkinson's disease

Cerebrospinal fluid (CSF) and serum or plasma concentrations of albumin, IgG and carbidopa were measured before and after adrenal-brain transplantation in patients with Parkinson's disease to indirectly assess blood-brain barrier (BBB) integrity. Previous studies in animals have suggested that the BBB is compromised by cerebral transplantation. CSF and plasma levodopa was also measured to permit comparison with the carbidopa values, recognizing that levodopa readily crosses the BBB via facilitated transport. Our patients underwent adrenal-brain transplantation in accordance with the method of Madrazo et al. (I. Madrazo, R. Drucker-Colin, V. Diaz, J. Martinez-Mata, C. Torres, and J. J. Becerril, 1987, N. Engl. J. Med. 316: 831-834) in which adrenal medullary pieces are implanted in the head of the caudate nucleus, in contact with the cerebrospinal fluid. All patients were maintained on oral carbidopa/levodopa therapy after surgery. CSF albumin/serum albumin and CSF IgG/serum IgG ratios were initially elevated above the preoperative baseline 6 weeks after the surgery; however, these values returned to the preoperative baseline by 6 months following the operation in six of seven patients. This suggested that the BBB was sufficiently intact to exclude these larger protein molecules from the CSF of these six patients. On the other hand, exogenously administered carbidopa, which normally is largely excluded from the cerebrospinal fluid by the BBB, was modestly increased in the CSF in four of the five patients in which it was measured. This suggests that the transplant BBB might be partially patent to small molecules for at least 6 months after the surgery. Whether increased passage of carbidopa into CSF and perhaps the transplant is of clinical significance has yet to be determined. Median CSF levodopa did not increase after surgery, probably because a limited defect in the BBB would be likely to be overshadowed by the effects of facilitated transport. CT scans performed following intravenous iothalamate meglumine contrast failed to reveal enhancement (dye leakage) near the transplantation site; however, artifact from the metal surgical clips used in the Madrazo procedure prevented good visualization of the area.

Catecholamines in CSF, plasma, and tissue after autologous transplantation of adrenal medulla to the brain in patients with Parkinson's disease

Catecholamine concentrations were measured in tissue samples of caudate and adrenal medulla in eight patients with Parkinson's disease who were taking L-dopa and were undergoing autologous transplantation of adrenal medulla to caudate nucleus. High-performance liquid chromatography with electrochemical detection was used for the measurement of analytes. Dopamine concentrations were quite similar in the caudate and the adrenal medulla; epinephrine and norepinephrine concentrations were some 600 times and 90 times higher, respectively, than that of dopamine in adrenal medulla but were barely detectable in caudate nucleus. Catecholamines and metabolites were also measured, before and after transplantation, in lumbar cerebrospinal fluid (CSF) and plasma 1 hour after the patients' first morning dose of L-dopa. The major fractions of the catecholamines in CSF were sulfoconjugated. The concentrations of sulfoconjugated but not free dopamine were modestly increased in CSF after the transplantation, although plasma concentrations were unchanged. CSF concentrations of free and conjugated norepinephrine and epinephrine, 3-methoxy-4-hydroxyphenylglycol, and homovanillic acid were unchanged after the transplantation. The data suggest that the grafted tissue does not retain its noradrenergic or adrenergic properties after transplantation, and that dopamine formation in the brain may be modestly increased. Plasma catecholamines were unaffected after the removal of one adrenal gland for the transplant.

Decreased adrenal medullary catecholamines in adrenal transplanted parkinsonian patients compared to nephrectomy patients

Adrenal medullary catecholamines were measured in tissue samples from eight patients who underwent autologous transplantation of the adrenal medulla to the caudate nucleus as a treatment for Parkinson's disease. These adrenal catecholamine levels were compared to a group of patients of similar age who underwent unilateral nephrectomy for renal cell carcinoma. The levels of each catecholamine, expressed as nanomoles per milligram wet weight tissue, were significantly lower (P less than or equal to 0.005) in the parkinsonian patients than in the nephrectomy patients. These observations support data reported previously from autopsy specimens and suggest that the adrenal medullae of parkinsonian patients may be a compromised source of dopamine-producing tissue; this may limit its effectiveness in eliciting maximum clinical improvement following transplantation.

Decreased catecholamine content in parkinsonian adrenal medullae

Autopsy specimens of adrenal medullae from parkinsonian and nonparkinsonian patients were analyzed for free catecholamines by high-performance liquid chromatography with electrochemical detection. The total free catecholamine content (nanomoles free catecholamine per milligram protein) was significantly lower in the parkinsonian patients than in the control population when the values were corrected for age and time from death to organ harvest. It is not established whether this decreased catecholamine content in the adrenals of parkinsonian patients is a concomitant of the disease itself or whether it is secondary to drug therapies used to treat the symptoms of Parkinson's disease.

Adrenal medullary autograft transplantation into the striatum of patients with Parkinson's disease

In eight patients with advanced Parkinson's disease, we performed autograft transplantation of adrenal medulla to the head of the caudate nucleus. Our technique was similar to that developed by Madrazo and co-workers in Mexico City. No major perioperative complications occurred except for somnolence in one patient for 8 days postoperatively. The follow-up period has been at least 6 months in seven of the patients, and only limited benefit has been apparent. The early morning Parkinson examination score in the "off" (unmedicated) state was significantly improved in one patient and slightly better in the other six. Diary card entries suggested a mild trend toward improvement (not statistically significant). Four of the seven patients were taking less levodopa 6 months after the operation than they had been preoperatively; three of five patients were no longer taking dopamine agonists postoperatively. We cannot exclude a placebo effect contributing to any of this improvement. A reduction in medication-induced dyskinesia was also noted, but this result may have been due to adjustments in doses or a slightly less potent effect of medication (or both factors). In summary, we have not yet been able to replicate the dramatic success reported for adrenal medullary transplantation by Madrazo's group, although our patients may have experienced mild to moderate improvement. We continue to maintain follow-up surveillance of these patients.

Effect of acute and chronic spinal transection on evoked secretion of adrenal medullary catecholamines in the cat

Eight cats were spinally transected at T3. After an acute (0-5 days) or chronic (15-37 days) period, animals were rendered decerebrate and the effects of visceral (bladder distention) and somatic (sciatic nerve stimulation) stimuli were examined. Epinephrine, norepinephrine and dopamine levels were measured in plasma collected from the left adrenolumbar vein; heart rate and blood pressure were continuously monitored. In chronic animals both visceral and somatic stimuli most frequently evoked prominent increases in blood pressure and the secretion of adrenal medullary catecholamines; the same stimuli caused little change in these parameters in acute animals. These data indicate that a condition similar to the clinical syndrome of autonomic hyperreflexia may be elicited in the chronic spinally transected cat, and that this condition is accompanied by a notable activation of the adrenal medulla.

Locating the lateral antebrachial cutaneous nerve

Dissections of 20 antebrachial specimens were done to define the location of the proximal lateral antebrachial cutaneous nerve, which is the distal sensory extension of the musculocutaneous nerve. Our findings varied from those noted in most anatomic and surgical texts in that the nerve emerges from the lateral aspect of the biceps tendon at the level of the interepicondylar line. At the point defined, the distribution of the nerve in ten volunteers was successfully anesthetized with 1.5 ml of 1% lidocaine. The accurate anatomic localization of this nerve should be of interest to surgeons and anesthesiologists in supplementing failed axillary blockade, in diagnosing and treating the musculocutaneous impingement syndrome, in harvesting the proximal nerve for diagnostic tests or donor graft purposes, and in differentiating the sensory distribution of this nerve from that of the radial nerve.

Opossum adrenal medulla: II. Differentiation of the chromaffin cell

The ultrastructure of the opossum adrenal medulla was examined in its postnatal development. Maturation of chromaffin cells and genesis of chromaffin vesicles were of particular interest. The primitive sympathetic cell was seen to contain few organelles with no apparent polarity. Initial pheochromoblasts contained more organelles with some polarity. Endoplasmic reticulum and the Golgi complex increased as the pheochromoblasts matured, which suggested increased synthetic activity. Structures resembling Golgi/endoplasmic reticulum/lysosome (GERL) systems were seen in the pheochromoblasts. It is suggested that some of the components of the chromaffin vesicle may be processed by the GERL while others come directly through the Golgi complex. It is stressed that the developing pheochromoblast in the opossum presents an interesting model in which to study the genesis of the chromaffin vesicle.

Opossum adrenal medulla: I. Postnatal development and normal anatomy

The anatomy and histology of the adrenal gland in the adult opossum were found to be typical for mammals. The development of the adrenal medulla was also found to follow the typical mammalian pattern. Primitive sympathetic cells were found in both intra- and extra-adrenal locations in the newborn at a time when chromaffin precursor cells were migrating to the adrenal anlage. Pheochromoblasts first appeared within the forming medulla where at a later stage chromaffin cells could be observed forming columns of cells between adjacent sinusoids. Unlike in other mammals, much of this development takes place postnatally when the neonate is in the mother's marsupium. The value of the developing opossum adrenal medulla as an experimental model is stressed, since a significant amount of development takes place in an environment that is accessible to experimental manipulation.

Ultrastructural demonstration of exocytosis in intact and saponin-permeabilized cultured bovine chromaffin cells

Exocytosis is the release of intracellular vesicular contents directly to the cell exterior after fusion of the vesicular and plasma membranes. It is generally accepted as the process by which transmitters and hormones are released from neurons and neurosecretory cells. There is overwhelming biochemical evidence that exocytosis is the mechanism by which catecholamines are released from adrenal chromaffin cells. With the exception of the hamster, however, there is little ultrastructural evidence to support such a mechanism. We have used a modified in vitro tannic-acid method to visualize exocytosis by transmission electron microscopy in intact and saponin-permeabilized bovine chromaffin cells. When cells are exposed to tannic-acid-containing medium, the content of vesicles involved in exocytosis is coagulated in situ as the vesicle opens to the exterior. Numerous exocytotic profiles were observed. The exposed vesicle contents appeared more granular than those of vesicles in the cell interior. Tannic acid also made the plasma membrane more distinct. Small holes were apparent in the plasma membrane of saponin-treated cells, with little disruption of underlying cytoplasmic structure. Furthermore, when these cells were stimulated with calcium, exocytosis was evident only at regions of intact plasma membrane, not at the holes. Parallel measurements of secretion showed no secretion in the presence of tannic acid. Pretreatment with tannic acid prevented subsequent secretion by intact cells and markedly reduced that of permeabilized cells, indicating a probable change in the nature of the plasma membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Androgen and estrogen effect on guinea pig seminal vesicle muscle: a combined stereological and biochemical study

A combined electron microscopic stereological and biochemical study of the smooth muscle cells of guinea pig seminal vesicles was performed in intact, castrated, castrated and dihydrotestosterone- or estradiol-treated adult animals. Castration led to cell atrophy as determined stereologically by a decreased single cell volume and biochemically by no change in DNA content coupled with an increase in the DNA concentration. Treatment of castrates with dihydrotestosterone restored both the stereological and biochemical parameters of the cell size to slightly supranormal levels. The estrogen-induced increase in muscle weight and DNA content appeared to be due only to hyperplasia of muscle cells and not to a proliferation of fibroblasts or to infiltration by inflammatory cells. In all treatment groups, including the estrogen-treated castrates, more than 95% of the cells in the tissue were smooth muscle cells, and there was no evidence that polyploidy contributed to changes in DNA levels. In addition, in the estrogen-treated muscles, DNA concentration remained high, and the stereologically determined cell size remained low. Therefore, both morphological and biochemical evidence indicate that androgen induces hypertrophy, whereas estrogen induces hyperplasia of muscle cells. The correction of stereological and biochemical data validates the application of stereological cell size determination for smooth muscle cells in organs that hardly can be separated into stromal and epithelial components; eg, the prostate.

Histochemical localization of monoamine oxidase types A and B in the adrenal gland

The distribution of monoamine oxidase types A and B within the adrenal gland was studied in several mammals by histochemical methods. Controls showed that the methods were valid. The bovine adrenal medulla contained mostly the B type enzyme, distributed heterogeneously, with some A type associated with endothelium, nerves, and cells surrounding the nerves. The bovine adrenal cortex showed a marked zonation of the two types of monoamine oxidase. The zona glomerulosa contained the B type enzyme and the zona fasciculata and zona reticularis contained the type A enzyme. The adrenal medulla of the dog, cat, and rat demonstrated relatively little enzyme activity and it appeared to be both type A and B. The adrenal cortex of these animals appeared to contain mostly the B type enzyme, except the canine zona reticularis, which contained some A type monoamine oxidase as well.

Supplemental clinical dissections for freshman gross anatomy

This paper describes a series of nine short clinically oriented dissection exercises as supplements for freshman gross anatomy courses. These procedures heighten and focus student interest, and they do not extensively lengthen the time required to accomplish the regular dissection assignments. The exercises are: lumbar puncture, anterior approach for shoulder arthroplasty, acromioclavicular dislocation, fenestration of the diaphragm, appendectomy, cholecystectomy, display of the facial nerve as in parotidectomy, posterior approach for hip arthroplasty, and injuries to the knee ligaments and meniscectomy.