Recent Publications by CFE Educators

Although there is considerable information about the mechanisms through which injury stimuli produce acute pain, recent studies indicate that there are significant long-term consequences of persistent injury. Pain is exacerbated, in part, because of a reorganization of spinal cord circuitry in the setting of persistent injury. This review describes our studies of the contribution of the primary afferent neurotransmitter, substance P (SP), to these changes. By following internalization of the SP receptor in spinal cord dorsal horn neurons, we have identified the stimuli that evoke SP release and the neurons that respond to these stimuli. Importantly, based on the intensities of stimuli required to evoke internalization, we conclude that SP is only released under conditions in which severe pain would be produced, that the release can be evoked by intense stimulation of somatic and visceral tissue, and that multiple stimulus modalities are effective. We also found that the numbers of neurons that are influenced increases dramatically in the setting of inflammation. Using a knockout strategy, we have also raised mice with a deletion of the preprotachykinin-A (PPT-A) gene, which encodes for SP and neurokinin A (NKA), and have identified a specific behavioral phenotype in which the animals do not detect a window of "pain" intensities; this window cuts across stimulus modalities. These results provide an important behavioral correlate of the receptor internalization studies. On the other hand, the allodynia (lowered pain threshold) that occurs in the setting of injury was not altered in these animals. Among the factors that could underlie injury-induced allodynia are the second messenger systems that are activated in dorsal horn neurons. Our studies have recently implicated the gamma isoform of protein kinase C (PKCgamma) in the development of nerve injury-induced neuropathic pain. Specifically, we found that although acute pain responses of mice with a deletion of PKCgamma are not altered, partial injury to the sciatic nerve (which induces a severe thermal and mechanical allodynia in the wild type mouse) is without effect in the knockout. Furthermore, the anatomical/neurochemical reorganization that typically follows sciatic nerve section does not occur in the PKCgamma mutant mice. Because the spinal cord distribution of interneurons that express PKCgamma is concentrated almost exclusively in the inner part of lamina II, we believe that changes in the properties of these neurons are key to the development of nerve injury-induced neuropathic pain conditions. Taken together, these studies emphasize that persistent pain should be considered a disease state of the nervous system, not merely a symptom of some other disease conditions. In the setting of persistent injury, the nervous system undergoes dramatic changes that exacerbate and prolong the pain condition. Our studies underscore the importance of preventing the long-term changes that result from persistent injury.

Activation of various second messengers contributes to long-term changes in the excitability of dorsal horn neurons and to persistent pain conditions produced by injury. Here, we compared the time-course of decreased mechanical nociceptive thresholds and the density of protein kinase Cgamma immunoreactivity in the dorsal horn after injections of complete Freund's adjuvant in the plantar surface of the rat hindpaw. Complete Freund's adjuvant significantly increased paw diameter and mechanical sensitivity ipsilateral to the inflammation. The changes peaked one day post-injury, but endured for at least two weeks. In these rats, we recorded a 75-100% increase in protein kinase Cgamma immunoreactivity in the ipsilateral superficial dorsal horn of the L4 and L5 segments at all time-points. Electron microscopy revealed that the up-regulation was associated with a significant translocation of protein kinase Cgamma immunoreactivity to the plasma membrane. In double-label cytochemical studies, we found that about 20% of the protein kinase Cgamma-immunoreactive neurons, which are concentrated in inner lamina II, contain glutamate decarboxylase-67 messenger RNA, but none stain for parvalbumin or nitric oxide synthase. These results indicate that persistent changes in protein kinase Cgamma immunoreactivity parallel the time-course of mechanical allodynia and suggest that protein kinase Cgamma contributes to the maintenance of the allodynia produced by peripheral inflammation. The minimal expression of protein kinase Cgamma in presumed inhibitory neurons suggests that protein kinase Cgamma-mediated regulation of excitatory interneurons underlies the changes in spinal cord activity during persistent nociception.

Characterization of intramyocardial coronary artery flow may offer insight into the spectrum of coronary physiology. The purposes of this study were to test the feasibility of detection and measurement of intramyocardial coronary artery flow by using high-frequency transthoracic ultrasound and to evaluate the hemodynamic and morphologic differences in intramyocardial coronary arteries between patients with echocardiographically normal myocardium and patients with diseased myocardium. In 116 subjects (age 58 +/- 19 years; male:female 67:49; 58 normal [control subjects], 40 with left ventricular hypertrophy [LVH], 18 with systolic left ventricular dysfunction [cardiomyopathy, CM]), we examined the myocardium just beneath the apical impulse window at a depth of 3 to 5 cm by using a 6- or 7-MHz centerline frequency transducer. For color Doppler examination, a special preset coronary program with a low Nyquist limit (12 to 20 cm) was used. After obtaining linear color signals, the width and length, peak and mean diastolic pulsed Doppler flow velocities, diastolic velocity time integrals, and percent duration of diastolic Doppler flow were measured. The number of linear color flow signals per square centimeter was counted in 520 different cardiac cycles, and the angles formed by their inner curvature was measured with a graduated protractor. We identified color flow Doppler signals within the myocardium having a mean width of 1.1 +/- 0.4 mm and flow direction from epicardium to endocardium in 104 (89. 7%) subjects and spectral Doppler signals in 74 (63.8%) subjects. In 33 (45.8%) subjects, only diastolic flow was detected and in 39 (54. 2%) subjects, diastolic flow was predominant with systolic reversal. Peak and mean diastolic flow velocities and velocity time integrals of spectral Doppler signal in control subjects were 26.2 +/- 8.6 cm/s, 19.0 +/- 6.3 cm/s, and 9.5 +/- 2.7 cm, respectively. There were no significant differences in width and density of linear color flow signals among the 3 groups. The color flow signals in the LVH and CM groups had a narrower angle of inner curvature (P .005 for LVH, P .05 for CM, respectively), and their spectral Doppler signals showed significantly higher diastolic velocities and shorter diastolic flow duration (P .005 for LVH, P .05 for CM, respectively) than those of the control subjects. Detection and measurement of flow signals consistent with penetrating intramyocardial coronary arteries are feasible in a high percentage of subjects by use of high-frequency transthoracic ultrasound. The findings in patients with LVH and CM suggest that there are distinct hemodynamic and morphologic departures from those with normal left ventricles that may be a consequence of disordered myocardial perfusion in diseased myocardium.

OBJECTIVE

To describe how and why attending physicians respond to learner behaviors that indicate negative attitudes toward patients.

SETTING

Inpatient general internal medicine service of a university-affiliated public hospital.

PARTICIPANTS

Four ward teams, each including an attending physician, a senior medicine resident, two interns, and up to three medical students.

DESIGN

Teams were studied using participant observation of rounds (160 hours); in-depth semistructured interviews (n = 23); a structured task involving thinking aloud (n = 4, attending physicians); and patient chart review. Codes, themes, and hypotheses were identified from transcripts and field notes, and iteratively tested by blinded within-case and cross-case comparisons.

MAIN RESULTS

Attending physicians identified three categories of potentially problematic behaviors: showing disrespect for patients, cutting corners, and outright hostility or rudeness. Attending physicians were rarely observed to respond to these problematic behaviors. When they did, they favored passive nonverbal gestures such as rigid posture, failing to smile, or remaining silent. Verbal responses included three techniques that avoided blaming learners: humor, referring to learners' self-interest, and medicalizing interpersonal issues. Attending physicians did not explicitly discuss attitudes, refer to moral or professional norms, "lay down the law," or call attention to their modeling, and rarely gave behavior-specific feedback. Reasons for not responding included lack of opportunity to observe interactions, sympathy for learner stress, and the unpleasantness, perceived ineffectiveness, and lack of professional reward for giving negative feedback.

CONCLUSIONS

Because of uncertainty about appropriateness and effectiveness, attending physicians were reluctant to respond to perceived disrespect, uncaring, or hostility toward patients by members of their medical team. They tended to avoid, rationalize, or medicalize these behaviors, and to respond in ways that avoided moral language, did not address underlying attitudes, and left room for face-saving reinterpretations. Although these oblique techniques are sympathetically motivated, learners in stressful clinical environments may misinterpret, undervalue, or entirely fail to notice such subtle feedback.

PURPOSE

To describe the development of the Washington Primary Care Interest Inventory (WPCII), which was designed to assess attitudes toward what constitutes appropriate psychosocial concerns for visiting a family physician, and to demonstrate the relationship between these attitudes and specialty selection in matriculating medical students.

METHOD

Five entering classes of medical students (1990 to 1995, without 1992) at the University of Washington were administered the WPCII during orientation. Reliability, factor, and predictive validity analyses were performed to measure the utility of the WPCII.

RESULTS

Factor analysis revealed three interpretable factors to underlie the WPCII: stressors, physical complaints, and familial complaints. Scales developed from these factors correlated with students' early career preferences and showed significant differences across students who were selected under different interviewing formats. Differences between the sexes were found for both specific items and scales.

CONCLUSION

The WPCII is a reliable and valid measure of attitudes toward the appropriateness of family physicians' treating psychosocial complaints. These attitudes have implications for the selection of medical students, curriculum development, assessment, and health education research.

OBJECTIVES

Two sequential outbreaks of respiratory disease among lifeguards at an indoor swimming pool with water spray features were investigated.

METHODS

Questionnaires were administered to recreation center employees following each outbreak. Respondents reporting 2 or more pool-related symptoms were offered clinical evaluation, including bronchoscopy with bronchoalveolar lavage and transbronchial biopsy. Pool air and water were sampled for fungi, bacteria, amoebae, endotoxin, and respirable particulates.

RESULTS

Thirty-three lifeguards had noncaseating granulomas on biopsy and/or bronchoalveolar lavage lymphocytosis. Attack rates for the outbreaks were 27% and 65%. Case patients had higher cumulative hours of work and tended to work more hours per week. Analyses indicated increased levels of endotoxin in pool air and water (relative to control pools) and gram-negative bacterial colonization of water sprays. Use of water spray features generated a 5.2-fold increase in the number of respirable particles and up to an 8-fold increase in air endotoxin levels.

CONCLUSIONS

Lifeguards in this indoor swimming pool developed granulomatous lung disease associated with endotoxin-containing respirable bioaerosols from water spray features, which ventilation system improvements did not prevent.

We report an outbreak of invasive Streptococcus pneumoniae disease in a chronic-care facility with a documented immunization rate of only 2.5%. We describe and discuss the infection control strategies used in prevention and management of such outbreaks, highlighting the role of immunization and presumptive chemotherapy.