Recent Publications by CFE Educators

When attending physicians are conducting teaching rounds, they rapidly decide what and how much to teach in response to each case presentation. How do they make these instructional decisions? The author performed a qualitative study of the instructional reasoning and actions of six distinguished clinical teachers in general internal medicine to address this question. Four data sources were used: interviews with teachers and learners, a structured task, transcripts of teaching rounds, and week-long observations of each ward team. The teachers in this study engaged in substantial amounts of planning before rounds and reflected on rounds afterwards. When listening to a case presentation during rounds, they quickly diagnosed the patient's problems and simultaneously diagnosed their learners' levels of understanding. These diagnostic assessments were used to tailor content-specific curriculum scripts for instruction. Throughout the rounds, the teachers also engaged in interactive thinking, decision making, and improvisation. The author's findings allowed him to hypothesize a model of clinical instructional reasoning and action; they contribute new insights into the interplay between reasoning in a discipline and pedagogical reasoning. Instructional reasoning and clinical reasoning were found to be closely linked through the use of scripts. The implications of these and other findings for medical faculty development are discussed.

The objective of this study was to determine the accuracy of a semiquantitative method of assessing the relative degree of cellularity and fibrosis compared with a morphometric analysis of specific histopathologic features in idiopathic pulmonary fibrosis (IPF). Morphometric analysis was performed on biopsy tissue from 20 patients. Morphometry showed that approximately 70% of parenchymal tissue was abnormal: 35% cellular consolidation and fibrosis, 20% honeycomb changes, 10% thick alveolar septa, and 5% small airways within abnormal parenchymal tissue. The prominent components of the abnormal parenchymal tissue were extracellular fibers, an abundance of interstitial cells, and epithelial cell hyperplasia. Correlation between four groupings of pathologic features, identified by a semiquantitative analysis, and each of the components of the parenchymal lesions showed significant correlations between (1) the fibrotic or reparative factor (alveolar wall metaplasia, fibrosis, honeycombing, and smooth muscle and vascular changes) and components of honeycomb lesions (extracellular fibers, interstitial cells, and epithelial injury and repair), and (2) the inflammatory and exudative factor and extracellular fibers in the lesions. These results support that the scoring system used by the pathology panel provides an accurate assessment of pathologic features useful in the assessment of the extent and severity of the histopathologic lesions of IPF.

Previous results from this laboratory demonstrated that plasma extravasation produced by intra-articular infusion of bradykinin in the rat is mediated by an action on the sympathetic terminals in the knee joint and that adrenal medullary epinephrine regulates the plasma extravasation provoked by bradykinin. Because the release of epinephrine is under cholinergic control, we have now evaluated the effect of nicotinic and muscarinic cholinergic agonists on bradykinin-induced plasma extravasation in the knee joint of the rat. We report that s.c. administration of nicotine and carbachol attenuated plasma extravasation induced by bradykinin; this attenuation was significantly antagonized by systemic injection of hexamethonium and atropine, respectively. The nicotine and carbachol effects were also significantly attenuated after removal of the adrenal medulla. These results indicate that both nicotine and carbachol can inhibit bradykinin-induced plasma extravasation and that this inhibition is mediated, at least in part, through activation of nicotinic and muscarinic receptors in the adrenal medulla. Finally, local perfusion of the knee joint with hexamethonium did not affect the inhibition of bradykinin-induced plasma extravasation produced by systemic nicotine. Intra-articular perfusion of atropine potentiated the inhibition of bradykinin-induced plasma extravasation by systemic carbachol, indicating that muscarinic receptors in the synovium also contribute to plasma extravasation. The inhibitory action of nicotine on plasma extravasation may contribute, in part, to the reported increased severity of arthritis in individuals who smoke.

Collagen deposition is a prime determinant of clinical course in idiopathic pulmonary fibrosis (IPF). Identification of a marker of connective tissue metabolism would significantly enhance the ability to stage the disease and monitor the course of these patients. Prior studies of IPF have indicated that N-terminal Type III procollagen peptide (N-PIIIP) levels in blood and bronchoalveolar lavage BAL fluid are elevated. We hypothesized that elevated levels of procollagen peptides are a marker of enhanced collagen deposition, which is associated with interstitial fibrosis characterizing active disease. The purpose of the present study was to explore the relationship between N-PIIIP recovery and physiologic parameters of lung function. N-PIIIP levels in sera and bronchoalveolar lavage (BAL) from 24 patients with IPF and 29 volunteers were measured by radioimmunoassay. The extent of disease in IPF was assessed by clinical history, physical examination, chest radiograph, pulmonary physiology evaluation, and confirmatory open-lung biopsy. The severity of disease was graded using a previously described clinical, radiologic, and physiologic (CRP) scoring system. N-PIIIP normalized to albumin was higher in BAL than in serum for both volunteers (1.6-fold; p less than 0.05) and IPF patients (24-fold; p less than 0.05), consistent with local pulmonary production. BAL N-PIIIP was significantly elevated in IPF patients, whether expressed as concentration (healthy volunteer 0.11 +/- 0.06 ng/ml; IPF, 5.0 +/- 14.4; mean +/- SD; p less than 0.05) or normalized to albumin (healthy volunteer, 2.8 +/- 1.2; IPF, 73 +/- 106; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVE

Hypersensitivity pneumonitis refers to a group of pulmonary disorders caused by inhalation of organic or inorganic particulates by sensitized persons. The diagnosis relies on a constellation of findings: exposure to an offending antigen, characteristic signs and symptoms, abnormal chest findings on physical examination, and abnormalities on pulmonary function tests and radiographic evaluation. In population-based studies, the sensitivity of chest radiography for detection of this disease is relatively low. The aim of this study was to determine the sensitivity of high-resolution CT (HRCT) for detection of hypersensitivity pneumonitis diagnosed in a population of swimming-pool employees.

SUBJECTS AND METHODS

Thirty-one symptomatic employees of a recreation center who were referred because of possible hypersensitivity pneumonitis were examined by using chest radiography, HRCT, and fiberoptic bronchoscopy with bronchoalveolar lavage and transbronchial biopsy. Hypersensitivity pneumonitis was diagnosed in subjects who had two or more work-related signs or symptoms, abnormal results on transbronchial biopsies, and abnormal lymphocytosis as shown by examination of bronchoalveolar lavage fluid. The chest radiographs and HRCT scans were interpreted by consensus by two observers who were unaware of the clinical diagnosis.

RESULTS

Only one of 11 subjects with a diagnosis of hypersensitivity pneumonitis had abnormal findings on a chest radiograph. Five had abnormal HRCT findings. The abnormality in each case consisted of small, poorly defined centrilobular nodules with variable profusion. No subject without the disease had abnormal HRCT findings. Those who had granulomas shown by lung biopsy were more likely to have abnormal HRCT findings than were those who had more subtle histologic abnormalities.

CONCLUSION

The sensitivity of HRCT for the detection of hypersensitivity pneumonitis in a population-based study is greater than that of chest radiography. The finding of poorly defined centrilobular nodules on HRCT scans should prompt consideration of this disease.

In a search for CO2 chemoreceptor neurons in the brain stem, we used immunocytochemistry to monitor the expression of neuronal c-fos, a marker of increased activity, after 1 h of exposure to CO2 in five groups of Sprague-Dawley rats (294 +/- 20 g): five air breathing controls, three breathing 10% CO2, three breathing 13% CO2, three breathing 15% CO2, and three breathing 15% CO2 and treated with morphine (10 mg/kg sc). After exposure the rats were anesthetized with pentobarbital sodium and perfused intracardially with 4% paraformaldehyde. The brain stem was removed and cryoprotected, and then 50-microns frozen sections were cut and immunostained for the fos protein. Brain stem fos-immunoreactive neurons were plotted and counted in the superficial 0.5 mm of the ventral medullary surface. Thirteen to 15% CO2 evoked fos-like immunoreactivity (FLI) in 321 +/- 146 neurons/rat. Significant CO2-induced labeling was confined within the superficial 150 microns: 67% of identified cells were less than 50 microns below the surface, greater than 90% between 1.0 and 3.0 mm from the midline, and approximately 60% in the rostral half of the medulla. Thirteen to 15% CO2 also evoked FLI in the area of the nucleus tractus solitarius but not in other medullary regions. Morphine (10 mg/kg sc) did not suppress high CO2-evoked FLI in either the ventral medullary surface or the nucleus tractus solitarius, although it eliminated excitement and hyperventilation. We suggest that respiratory CO2 chemoreceptor neurons can be identified in rats by their expression of c-fos after 1 h of hypercapnia.(ABSTRACT TRUNCATED AT 250 WORDS)

We describe a microdialysis probe with attached side catheter for making submicroliter injections at the site of the probe in the awake, freely moving rat. This design allows the local application of drugs which cannot be applied in the perfusion medium either because of their inability to pass through the dialysis membrane or because of their interference with chromatographic detection of compounds of interest.

Cryptogenic organizing pneumonitis is a clinical and pathologic syndrome characterized by a "pneumonia-like" illness with excessive proliferation of granulation tissue within small airways and alveolar ducts associated with chronic inflammation in the surrounding alveoli. The duration of illness prior to lung biopsy is short, usually less than 2 months, and it is markedly different from that of IPF. Interestingly, unlike in IPF where the patient has difficulty remembering the exact onset of symptoms, patients with COP are frequently very specific about the timing of their disease onset. This is because the disease onset is recent and is often dramatic with the development of a severe flulike illness, ie, cough, fever, malaise, fatigue, and weight loss. Inspiratory crackles are frequently present on chest examination. Pulmonary function is usually impaired with a restrictive defect being most common. Gas exchange abnormalities are extremely common with a reduction in Dco and resting hypoxemia being almost universal findings. The roentgenographic manifestations are quite distinctive with a pattern of bilateral, diffuse but inhomogeneous, ground-glass or alveolar opacities being present in the majority of the cases. Bronchoalveolar lavage findings are nonspecific but usually reveal a lymphocytosis. The response to corticosteroid treatment is quite favorable and death from progressive disease is uncommon in COP, especially if treatment is instituted early in the course of the disease. In our experience, the cases with the worse prognosis are those associated with another disease process, in particular, connective tissue disorders like rheumatoid arthritis. In fact, these patients are prone to develop a rapidly progressive form of BOOP with a clinical course similar to the "Hamman-Rich syndrome." Recurrences are relatively frequent, consequently, withdrawal of treatment should be done with extreme caution. Corticosteroids have been the conventional initial treatment of COP, although to our knowledge, there are no controlled clinical trials to support it use. Antibiotics are not effective in treating this syndrome. Thus, based solely on our experience and that of others, we believe that high-dose corticosteroid therapy should be used to treat COP, usually initiated with 1 to 1.5 mg/kg/day (using ideal body weight) not to exceed 100 mg/day. Prednisone is given as a single oral dose in the morning. We recommended maintaining this dose for 4 to 8 weeks. If the patient's condition is stable or improved, the prednisone dosage is gradually tapered to 0.5 to 1 mg/kg/day (using ideal body weight) for the ensuing 4 to 6 weeks.(ABSTRACT TRUNCATED AT 400 WORDS)